Using field data to assess the tolerance of freshwater fish to elevated ionic concentrations

EPA Science Inventory

We used field data of fish occurrences and specific conductivity to assess the tolerance of freshwater fish to elevated ions. The concentration at which a species was expected to no longer be observed [the extirpation concentration (XC95)] was identified from the 95th percentile ...

Regression models for estimating salinity and selenium concentrations at selected sites in the Upper Colorado River Basin, Colorado, 2009-2012

USGS Publications Warehouse

Linard, Joshua I.; Schaffrath, Keelin R.

2014-01-01

Elevated concentrations of salinity and selenium in the tributaries and main-stem reaches of the Colorado River are a water-quality concern and have been the focus of remediation efforts for many years. Land-management practices with the objective of limiting the amount of salt and selenium that reaches the stream have focused on improving the methods by which irrigation water is conveyed and distributed. Federal land managers implement improvements in accordance with the Colorado River Basin Salinity Control Act of 1974, which directs Federal land managers to enhance and protect the quality of water available in the Colorado River. In an effort to assist in evaluating and mitigating the detrimental effects of salinity and selenium, the U.S. Geological Survey, in cooperation with the Bureau of Reclamation, the Colorado River Water Resources District, and the Bureau of Land Management, analyzed salinity and selenium data collected at sites to develop regression models. The study area and sites are on the Colorado River or in one of three small basins in Western Colorado: the White River Basin, the Lower Gunnison River Basin, and the Dolores River Basin. By using data collected from water years 2009 through 2011, regression models able to estimate concentrations were developed for salinity at six sites and selenium at six sites. At a minimum, data from discrete measurement of salinity or selenium concentration, streamflow, and specific conductance at each of the sites were needed for model development. Comparison of the Adjusted R2 and standard error statistics of the two salinity models developed at each site indicated the models using specific conductance as the explanatory variable performed better than those using streamflow. The addition of multiple explanatory variables improved the ability to estimate selenium concentration at several sites compared with use of solely streamflow or specific conductance. The error associated with the log-transformed salinity and selenium estimates is consistent in log space; however, when the estimates are transformed into non-log values, the error increases as the estimates decrease. Continuous streamflow and specific conductance data collected at study sites provide the means to examine temporal variability in constituent concentration and load. The regression models can estimate continuous concentrations or loads on the basis of continuous specific conductance or streamflow data. Similar estimates are available for other sites at the USGS National Real-Time Water Quality Web page (http://nrtwq.usgs.gov) and provide water-resource managers with a means of improving their general understanding of how constituent concentration or load can change annually, seasonally, or in real time.

Simulation of water-quality data at selected stream sites in the Missouri River Basin, Montana

USGS Publications Warehouse

Knapton, J.R.; Jacobson, M.A.

1980-01-01

Modification of sampling programs at some water-quality stations in the Missouri River basin in Montana has eliminated the means by which solute loads have been directly obtained in past years. To compensate for this loss, water-quality and streamflow data were statistically analyzed and solute loads were simulated using computer techniques.Functional relationships existing between specific conductance and solute concentration for monthly samples were used to develop linear regression models. The models were then used to simulate daily solute concentrations using daily specific conductance as the independent variable. Once simulated, the solute concentrations, in milligrams per liter, were transformed into daily solute loads, in tons, using mean daily streamflow records.Computer output was formatted into tables listing simulated mean monthly solute concentrations, in milligrams per liter, and the monthly and annual solute loads, in tons, for water years 1975-78.

Quality of ground water in Harrison County, Mississippi, June - July 1993

USGS Publications Warehouse

Slack, L.J.; Oakley, W.T.; O'Hara, C. G.; Cooper, L.M.

1994-01-01

During June and July 1993, the U.S. Geological Survey analyzed water from 145 wells in Harrison County, southeastern Mississippi. The wells are completed in five major geologic units: the Citronelle, Graham Ferry, Pascagoula, and Hattiesburg Formations and the Catahoula Sandstone. The wells ranged from 74 to 2,410 feet in depth. Specific conductance (lab) ranged from 15 to 2,020 microsiemens per centimeter; pH (lab), from 5.9 to 9.0; color, from less than 5 to 120 platinum-cobalt units; dissolved-solids concentrations (residue on evaporation), from 20 to 1,120 milligrams per liter; chloride concentrations, from 1.9 to 470 milligrams per liter; and nitrite plus nitrate as nitrogen concentrations, from less than 0.02 to 0.85 milligram per liter. Most of the larger values of specific conductance, pH, dissolved-solids concen- trations, and chloride concentrations were from wells in the southern one-half of the county.

Effect of Temperature and Nutrient Manipulations on eelgrass ...

EPA Pesticide Factsheets

Global climate change will have a large impact on the three predominate drivers of estuarine seagrass productivity, temperature, light and nutrients. I experimentally evaluate the response of Pacific Northwest Z. marina to interactive effects of temperature and nutrient conditions. Experimental manipulations were conducted hydroponically in acrylic chambers and spanned a range of temperatures and nutrient concentrations. Preliminary single factor experiments were conducted to evaluate physiological tolerances to temperature and nitrogen concentrations. Eelgrass exhibited a linear increase in specific growth with increasing NH4 concentration (range from 10 to 1000 µM); in contrast, there was no significant relationship between specific growth rate and increasing NO3 concentration over the same concentration range. Leaf growth metrics all exhibited strong linear relationships with increasing water temperature (temperature range 4-25 ºC). In the factorial experiment, plants were exposed to 3 temperatures (10, 18 and 25 ºC) and 3 nitrate concentrations (10, 30 and 100 µM) with 3 replicate chambers per treatment combination. Most metrics (leaf elongation, growth, specific growth, wasting index) exhibited a significant temperature effect indicating the importance of temperature on metabolic rates. Tissue stable isotope ratios and C:N values exhibited a significant nutrient effect and in some cases a significant temperature effect. Whole plant non structur

Quality of water and time-of-travel in Bakers Creek near Clinton, Mississippi. [Bakers Creek

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kalkhoff, S.J.

1982-01-01

A short-term intensive quality-of-water study was conducted during a period of generally low streamflow in Bakers Creek and its tributary, Lindsey Creek, near Clinton, Mississippi. During the September 15-18, 1980 study, dissolved oxygen concentrations in Bakers Creek were less than 5 milligrams per liter. The specific conductance, 5-day biochemical oxygen demand, nutrient concentrations, and bacteria densities in Bakers Creek decreased downstream through the study reach. The mean specific conductance decreased from 670 to 306 microhms per centimeter. The 5-day biochemical oxygen demand decreased from 19 to 2.8 milligrams per liter. The mean total nitrogen and phosphorous concentrations decreased from 10more » and 7.1 to 1.0 and 0.87 milligram per litter, respectively. The maximum fecal bacteria decreased from 7200 to 400 colonies per 100 milliliter. The concentrations of mercury, iron, and manganese in a sample collected at the downstream site exceeded recommended limits. Diazinon and 2,4-D were also present in the water. A bottom material sample contained DDD (2.5 micrograms per kilogram), DDE (2.7 micrograms per kilogram), and DDT (.3 micrograms per kilogram). The tributary inflow from Lindsey Creek did not improve the water quality of Bakers Creek. The dissolved oxygen concentrations were generally less than 5.0 milligrams per liter at the sampling site on Lindsey Creek. The 5-day biochemical oxygen demand, the mean specific conductance, and fecal coliform densities were greater in the tributary than at the downstream site on Bakers Creek. The average rate of travel through a 1.8-mile reach of Bakers Creek was 0.06 foot per second or 0.04 miles per hour. 6 references, 9 figures, 2 tables.« less

Statistical summaries of water-quality data for two coal areas of Jackson County, Colorado

USGS Publications Warehouse

Kuhn, Gerhard

1982-01-01

Statistical summaries of water-quality data are compiled for eight streams in two separate coal areas of Jackson County, Colo. The quality-of-water data were collected from October 1976 to September 1980. For inorganic constituents, the maximum, minimum, and mean concentrations, as well as other statistics are presented; for minor elements, only the maximum, minimum, and mean values are included. Least-squares equations (regressions) are also given relating specific conductance of the streams to the concentration of the major ions. The observed range of specific conductance was 85 to 1,150 micromhos per centimeter for the eight sites. (USGS)

Water levels and water quality in the Mississippi River Valley alluvial aquifer in eastern Arkansas, 2012

USGS Publications Warehouse

Schrader, Tony P.

2015-01-01

Water samples were collected in the summer of 2012 from142 wells completed in the alluvial aquifer and measured onsite for specific conductance, temperature, and pH. Samples were collected from 94 wells for dissolved chloride analysis. Specific conductance ranged from 91 microsiemens per centimeter at 25 degrees Celsius (μS/cm at 25 °C) in Drew County to 984 μS/cm at 25 °C in Monroe County. The mean specific conductance was 547 μS/cm at 25 °C. Temperature ranged from 18.1 degrees Celsius (°C) in Crittenden County to 22.4 °C in Prairie County. The mean temperature was 22.1 °C. The pH ranged from 8.3 in Randolph County to 6.2 in Drew County and had a median of 7.3. Dissolved chloride concentrations ranged from 3.34 milligrams per liter (mg/L) in Randolph County to 182 mg/L in Lincoln County. The mean chloride concentration was 27.6 mg/L.

Simulation of specific conductance and chloride concentration in Abercorn Creek, Georgia, 2000-2009

USGS Publications Warehouse

Conrads, Paul; Roehl, Edwin A.; Davie, Steven R.

2011-01-01

The City of Savannah operates an industrial and domestic water-supply intake on Abercorn Creek approximately 2 miles from the confluence with the Savannah River upstream from the Interstate 95 bridge. Chloride concentrations are a major concern for the city because industrial customers require water with low chloride concentrations, and elevated chloride concentrations require additional water treatment in order to meet those needs. The proposed deepening of Savannah Harbor could increase chloride concentrations (the major ion in seawater) in the upper reaches of the lower Savannah River estuary, including Abercorn Creek. To address this concern, mechanistic and empirical modeling approaches were used to simulate chloride concentrations at the city's intake to evaluate potential effects from deepening the Savannah Harbor. The first approach modified the mechanistic Environmental Fluid Dynamics Code (EFDC) model developed by Tetra Tech and used for evaluating proposed harbor deepening effects for the Environmental Impact Statement. Chloride concentrations were modeled directly with the EFDC model as a conservative tracer. This effort was done by Tetra Tech under a separate funding agreement with the U.S. Army Corps of Engineers and documented in a separate report. The second approach, described in this report, was to simulate chloride concentrations by developing empirical models from the available data using artificial neural network (ANN) and linear regression models. The empirical models used daily streamflow, specific conductance (field measurement for salinity), water temperature, and water color time series for inputs. Because there are only a few data points that describe the relation between high specific conductance values at the Savannah River at Interstate 95 and the water plant intake, there was a concern that these few data points would determine the extrapolation of the empirical model and potentially underestimate the effect of deepening the harbor on chloride concentrations at the intake. To accommodate these concerns, two ANN chloride models were developed for the intake. The first model (ANN M1e) used all the data. The second model (ANN M2e) only used data when specific conductance at Interstate 95 was less than 175 microsiemens per centimeter at 25 degrees Celsius. Deleting the conductivity data greater than 175 microsiemens per centimeter removed the "plateau" effect observed in the data. The chloride simulations with the ANN M1 model have a low sensitivity to specific conductance (salinity) at Interstate 95, whereas the chloride simulations with the ANN M2 model have a high sensitivity to salinity at Interstate 95. The two modeling approaches (Tetra Tech's EFDC model and the one described in this report) were integrated into a decision support system (DSS) that combines the historical database, output from EFDC, ANN models, ANN model simulation controls, streaming graphics, and model output. The DSS was developed as a Microsoft ExcelTM/Visual Basic for Applications program, which allowed the DSS to be prototyped, easily modified, and distributed in a familiar spreadsheet format. The EFDC and ANN models were used to simulate various harbor deepening scenarios. To accommodate the geometry changes in the harbor, the ANN models used the EFDC model-simulated salinity changes for a historical condition as input. The DSS uses a graphical user interface and allows the user to interrogate the ANN models and EFDC output. Two scenarios were simulated using the Savannah Chloride Model DSS to demonstrate different input options. One scenario decreased winter streamflows to a constant streamflow for 45 days. Streamflows during the period January 1 to February 15 were set to a constant 3,600 cubic feet per second for the simulation period of October 1, 2006, to October 1, 2009. The decreased winter streamflow resulted in predictions of increased specific conductance by as much as 50 microsiemens per centimeter and chlorid

A fresh look at road salt: aquatic toxicity and water-quality impacts on local, regional, and national scales.

PubMed

Corsi, Steven R; Graczyk, David J; Geis, Steven W; Booth, Nathaniel L; Richards, Kevin D

2010-10-01

A new perspective on the severity of aquatic toxicity impact of road salt was gained by a focused research effort directed at winter runoff periods. Dramatic impacts were observed on local, regional, and national scales. Locally, samples from 7 of 13 Milwaukee, Wisconsin area streams exhibited toxicity in Ceriodaphnia dubia and Pimephales promelas bioassays during road-salt runoff. Another Milwaukee stream was sampled from 1996 to 2008 with 72% of 37 samples exhibiting toxicity in chronic bioassays and 43% in acute bioassays. The maximum chloride concentration was 7730 mg/L. Regionally, in southeast Wisconsin, continuous specific conductance was monitored as a chloride surrogate in 11 watersheds with urban land use from 6.0 to 100%. Elevated specific conductance was observed between November and April at all sites, with continuing effects between May and October at sites with the highest specific conductance. Specific conductance was measured as high as 30,800 μS/cm (Cl = 11,200 mg/L). Chloride concentrations exceeded U.S. Environmental Protection Agency (USEPA) acute (860 mg/L) and chronic (230 mg/L) water-quality criteria at 55 and 100% of monitored sites, respectively. Nationally, U.S. Geological Survey historical data were examined for 13 northern and 4 southern metropolitan areas. Chloride concentrations exceeded USEPA water-quality criteria at 55% (chronic) and 25% (acute) of the 168 monitoring locations in northern metropolitan areas from November to April. Only 16% (chronic) and 1% (acute) of sites exceeded criteria from May to October. At southern sites, very few samples exceeded chronic water-quality criteria, and no samples exceeded acute criteria.

Elevated major ion concentrations inhibit larval mayfly growth and development.

PubMed

Johnson, Brent R; Weaver, Paul C; Nietch, Christopher T; Lazorchak, James M; Struewing, Katherine A; Funk, David H

2015-01-01

Anthropogenic disturbances, including those from developing energy resources, can alter stream chemistry significantly by elevating total dissolved solids. Field studies have indicated that mayflies (Order Ephemeroptera) are particularly sensitive to high total dissolved solids. In the present study, the authors measured 20-d growth and survivorship of larval Neocloeon triangulifer exposed to a gradient of brine salt (mixed NaCl and CaCl2 ) concentrations. Daily growth rates were reduced significantly in all salt concentrations above the control (363 µS cm(-1) ) and larvae in treatments with specific conductance >812 µS cm(-1) were in comparatively earlier developmental stages (instars) at the end of the experiment. Survivorship declined significantly when specific conductance was >1513 µS cm(-1) and the calculated 20-d 50% lethal concentration was 2866 µS cm(-1) . The present study's results provide strong experimental evidence that elevated ion concentrations similar to those observed in developing energy resources, such as oil and gas drilling or coal mining, can adversely affect sensitive aquatic insect species. © 2014 SETAC.

External quality-assurance results for the National Atmospheric Deposition Program / National Trends Network and Mercury Deposition Network, 2004

USGS Publications Warehouse

Wetherbee, Gregory A.; Latysh, Natalie E.; Greene, Shannon M.

2006-01-01

The U.S. Geological Survey (USGS) used five programs to provide external quality-assurance monitoring for the National Atmospheric Deposition Program/National Trends Network (NADP/NTN) and two programs to provide external quality-assurance monitoring for the NADP/Mercury Deposition Network (NADP/MDN) during 2004. An intersite-comparison program was used to estimate accuracy and precision of field-measured pH and specific-conductance. The variability and bias of NADP/NTN data attributed to field exposure, sample handling and shipping, and laboratory chemical analysis were estimated using the sample-handling evaluation (SHE), field-audit, and interlaboratory-comparison programs. Overall variability of NADP/NTN data was estimated using a collocated-sampler program. Variability and bias of NADP/MDN data attributed to field exposure, sample handling and shipping, and laboratory chemical analysis were estimated using a system-blank program and an interlaboratory-comparison program. In two intersite-comparison studies, approximately 89 percent of NADP/NTN site operators met the pH measurement accuracy goals, and 94.7 to 97.1 percent of NADP/NTN site operators met the accuracy goals for specific conductance. Field chemistry measurements were discontinued by NADP at the end of 2004. As a result, the USGS intersite-comparison program also was discontinued at the end of 2004. Variability and bias in NADP/NTN data due to sample handling and shipping were estimated from paired-sample concentration differences and specific conductance differences obtained for the SHE program. Median absolute errors (MAEs) equal to less than 3 percent were indicated for all measured analytes except potassium and hydrogen ion. Positive bias was indicated for most of the measured analytes except for calcium, hydrogen ion and specific conductance. Negative bias for hydrogen ion and specific conductance indicated loss of hydrogen ion and decreased specific conductance from contact of the sample with the collector bucket. Field-audit results for 2004 indicate dissolved analyte loss in more than one-half of NADP/NTN wet-deposition samples for all analytes except chloride. Concentrations of contaminants also were estimated from field-audit data. On the basis of 2004 field-audit results, at least 25 percent of the 2004 NADP/NTN concentrations for sodium, potassium, and chloride were lower than the maximum sodium, potassium, and chloride contamination likely to be found in 90 percent of the samples with 90-percent confidence. Variability and bias in NADP/NTN data attributed to chemical analysis by the NADP Central Analytical Laboratory (CAL) were comparable to the variability and bias estimated for other laboratories participating in the interlaboratory-comparison program for all analytes. Variability in NADP/NTN ammonium data evident in 2002-03 was reduced substantially during 2004. Sulfate, hydrogen-ion, and specific conductance data reported by CAL during 2004 were positively biased. A significant (a = 0.05) bias was identified for CAL sodium, potassium, ammonium, and nitrate data, but the absolute values of the median differences for these analytes were less than the method detection limits. No detections were reported for CAL analyses of deionized-water samples, indicating that contamination was not a problem for CAL. Control charts show that CAL data were within statistical control during at least 90 percent of 2004. Most 2004 CAL interlaboratory-comparison results for synthetic wet-deposition solutions were within ?10 percent of the most probable values (MPVs) for solution concentrations except for chloride, nitrate, sulfate, and specific conductance results from one sample in November and one specific conductance result in December. Overall variability of NADP/NTN wet-deposition measurements was estimated during water year 2004 by the median absolute errors for weekly wet-deposition sample concentrations and precipitation measurements for tw

Water-quality reconnaissance of ground water in the inhabited outer islands of Chuuk State, Federated States of Micronesia, 1984-85

USGS Publications Warehouse

Hamlin, S.N.; Takasaki, K.J.

1996-01-01

A reconnaissance of ground-water quality in 24 inhabited outer islands in Chuuk State was made between January 1984 and October 1985. Most of the islands are part of low-lying coral atolls within the Western, Namonuito, Hall, and Mortlock Island Groups. A total of 648 wells were located and sampled for temperature and specific conductance. A few miscellaneous sites such as taro patches also were sampled. The nitrate concentration was determined for 308 water samples. To develop a relation between specific conductance and chloride concentration, the chloride concentration was determined for 63 water samples. In addition, 21 water samples were analyzed for major and trace constituent ion concentrations. Chloride and nitrate are the primary constituents affecting the potability of ground water in the inhabited outer islands of Chuuk State. The source of chloride in ground water is seawater, whereas nitrate is derived fro plant and animal waste materials. The chloride concentrations in many well waters exceed the World Health Organization guideline for drinking water, particularly in wells near the shoreline or on small islands. In addition, the nitrate concentrations in some well waters exceeded the World Health Organization guideline for drinking water.

Water-quality characteristics, trends, and nutrient and sediment loads of streams in the Treyburn development area, North Carolina, 1988–2009

USGS Publications Warehouse

Fine, Jason M.; Harned, Douglas A.; Oblinger, Carolyn J.

2013-01-01

Streamflow and water-quality data, including concentrations of nutrients, metals, and pesticides, were collected from October 1988 through September 2009 at six sites in the Treyburn development study area. A review of water-quality data for streams in and near a 5,400-acre planned, mixed-use development in the Falls Lake watershed in the upper Neuse River Basin of North Carolina indicated only small-scale changes in water quality since the previous assessment of data collected from 1988 to 1998. Loads and yields were estimated for sediment and nutrients, and temporal trends were assessed for specific conductance, pH, and concentrations of dissolved oxygen, suspended sediment, and nutrients. Water-quality conditions for the Little River tributary and Mountain Creek may reflect development within these basins. The nitrogen and phosphorus concentrations at the Treyburn sites are low compared to sites nationally. The herbicides atrazine, metolachlor, prometon, and simazine were detected frequently at Mountain Creek and Little River tributary but concentrations are low compared to sites nationally. Little River tributary had the lowest median suspended-sediment yield over the 1988–2009 study period, whereas Flat River tributary had the largest median yield. The yields estimated for suspended sediment and nutrients were low compared to yields estimated for other basins in the Southeastern United States. Recent increasing trends were detected in total nitrogen concentration and suspended-sediment concentrations for Mountain Creek, and an increasing trend was detected in specific conductance for Little River tributary. Decreasing trends were detected in dissolved nitrite plus nitrate nitrogen, total ammonia plus organic nitrogen, sediment, and specific conductance for Flat River tributary. Water chemical concentrations, loads, yields, and trends for the Treyburn study sites reflect some effects of upstream development. These measures of water quality are generally low, however, compared to regional and national averages.

Computational Fluid Dynamics Modeling of Bacillus anthracis Spore Deposition in Rabbit and Human Respiratory Airways

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kabilan, Senthil; Suffield, Sarah R.; Recknagle, Kurtis P.

Three-dimensional computational fluid dynamics and Lagrangian particle deposition models were developed to compare the deposition of aerosolized Bacillus anthracis spores in the respiratory airways of a human with that of the rabbit, a species commonly used in the study of anthrax disease. The respiratory airway geometries for each species were derived from computed tomography (CT) or µCT images. Both models encompassed airways that extended from the external nose to the lung with a total of 272 outlets in the human model and 2878 outlets in the rabbit model. All simulations of spore deposition were conducted under transient, inhalation-exhalation breathing conditionsmore » using average species-specific minute volumes. The highest exposure concentration was modeled in the rabbit based upon prior acute inhalation studies. For comparison, human simulation was also conducted at the same concentration. Results demonstrated that regional spore deposition patterns were sensitive to airway geometry and ventilation profiles. Due to the complex airway geometries in the rabbit nose, higher spore deposition efficiency was predicted in the upper conducting airways compared to the human at the same air concentration of anthrax spores. As a result, higher particle deposition was predicted in the conducting airways and deep lung of the human compared to the rabbit lung due to differences in airway branching pattern. This information can be used to refine published and ongoing biokinetic models of inhalation anthrax spore exposures, which currently estimate deposited spore concentrations based solely upon exposure concentrations and inhaled doses that do not factor in species-specific anatomy and physiology.« less

A Fresh Look at Road Salt: Aquatic Toxicity and Water-Quality Impacts on Local, Regional, and National Scales

PubMed Central

2010-01-01

A new perspective on the severity of aquatic toxicity impact of road salt was gained by a focused research effort directed at winter runoff periods. Dramatic impacts were observed on local, regional, and national scales. Locally, samples from 7 of 13 Milwaukee, Wisconsin area streams exhibited toxicity in Ceriodaphnia dubia and Pimephales promelas bioassays during road-salt runoff. Another Milwaukee stream was sampled from 1996 to 2008 with 72% of 37 samples exhibiting toxicity in chronic bioassays and 43% in acute bioassays. The maximum chloride concentration was 7730 mg/L. Regionally, in southeast Wisconsin, continuous specific conductance was monitored as a chloride surrogate in 11 watersheds with urban land use from 6.0 to 100%. Elevated specific conductance was observed between November and April at all sites, with continuing effects between May and October at sites with the highest specific conductance. Specific conductance was measured as high as 30 800 μS/cm (Cl = 11 200 mg/L). Chloride concentrations exceeded U.S. Environmental Protection Agency (USEPA) acute (860 mg/L) and chronic (230 mg/L) water-quality criteria at 55 and 100% of monitored sites, respectively. Nationally, U.S. Geological Survey historical data were examined for 13 northern and 4 southern metropolitan areas. Chloride concentrations exceeded USEPA water-quality criteria at 55% (chronic) and 25% (acute) of the 168 monitoring locations in northern metropolitan areas from November to April. Only 16% (chronic) and 1% (acute) of sites exceeded criteria from May to October. At southern sites, very few samples exceeded chronic water-quality criteria, and no samples exceeded acute criteria. PMID:20806974

A fresh look at road salt: Aquatic toxicity and water-quality impacts on local, regional, and national scales

USGS Publications Warehouse

Corsi, S.R.; Graczyk, D.J.; Geis, S.W.; Booth, N.L.; Richards, K.D.

2010-01-01

A new perspective on the severity of aquatic toxicity impact of road salt was gained by a focused research effort directed at winter runoff periods. Dramatic impacts were observed on local, regional, and national scales. Locally, samples from 7 of 13 Milwaukee, Wisconsin area streams exhibited toxicity in Ceriodaphnia dubia and Pimephales promelas bioassays during road-salt runoff. Another Milwaukee stream was sampled from 1996 to 2008 with 72% of 37 samples exhibiting toxicity in chronic bioassays and 43% in acute bioassays. The maximum chloride concentration was 7730 mg/L. Regionally, in southeast Wisconsin, continuous specific conductance was monitored as a chloride surrogate in 11 watersheds with urban land use from 6.0 to 100%. Elevated specific conductance was observed between November and April at all sites, with continuing effects between May and October at sites with the highest specific conductance. Specific conductance was measured as high as 30 800 ??S/cm (Cl = 11 200 mg/L). Chloride concentrations exceeded U.S. Environmental Protection Agency (USEPA) acute (860 mg/L) and chronic (230 mg/L) water-quality criteria at 55 and 100% of monitored sites, respectively. Nationally, U.S. Geological Survey historical data were examined for 13 northern and 4 southern metropolitan areas. Chloride concentrations exceeded USEPA water-quality criteria at 55% (chronic) and 25% (acute) of the 168 monitoring locations in northern metropolitan areas from November to April. Only 16% (chronic) and 1% (acute) of sites exceeded criteria from May to October. At southern sites, very few samples exceeded chronic water-quality criteria, and no samples exceeded acute criteria. ?? 2010 American Chemical Society.

Preliminary assessment of chloride concentrations, loads, and yields in selected watersheds along the Interstate 95 corridor, southeastern Connecticut, 2008-09

USGS Publications Warehouse

Brown, Craig J.; Mullaney, John R.; Morrison, Jonathan; Mondazzi, Remo

2011-01-01

Water-quality conditions were assessed to evaluate potential effects of road-deicer applications on stream-water quality in four watersheds along Interstate 95 (I-95) in southeastern Connecticut from November 1, 2008, through September 30, 2009. This preliminary study is part of a four-year cooperative study by the U.S. Geological Survey (USGS), the Federal Highway Administration (FHWA), and the Connecticut Department of Transportation (ConnDOT). Streamflow and water quality were studied at four watersheds?Four Mile River, Oil Mill Brook, Stony Brook, and Jordan Brook. Water-quality samples were collected and specific conductance was measured continuously at paired water-quality monitoring sites upstream and downstream from I-95. Specific conductance values were related to chloride (Cl) concentrations to assist in determining the effects of road-deicing operations on the levels of Cl in the streams. Streamflow and water-quality data were compared with weather data and with the timing, amount, and composition of deicers applied to state highways. Grab samples were collected during winter stormwater-runoff events, such as winter storms or periods of rain or warm temperatures in which melting takes place, and periodically during the spring and summer. Cl concentrations at the eight water-quality monitoring sites were well below the U.S. Environmental Protection Agency (USEPA) recommended chronic and acute Cl toxicity criteria of 230 and 860 milligrams per liter (mg/L), respectively. Specific conductance and estimated Cl concentrations in streams, particularly at sites downstream from I-95, peaked during discharge events in the winter and early spring as a result of deicers applied to roads and washed off by stormwater or meltwater. During winter storms, deicing activities, or subsequent periods of melting, specific conductance and estimated Cl concentrations peaked as high as 703 microsiemens per centimeter (?S/cm) and 160 mg/L at the downstream sites. During most of the spring and summer, specific conductance and estimated Cl concentrations decreased during discharge events because the low-ionic strength of stormwater had a diluting effect on stream-water quality. However, peaks in specific conductance and estimated Cl concentrations at Jordan Brook and Stony Brook corresponded to peaks in streamflow well after winter snow or ice events; these delayed peaks in Cl concentration likely resulted from deicing salts that remained in melting snow piles and (or) that were flushed from soils and shallow groundwater, then discharged downstream. Cl loads in streams generally were highest in the winter and early spring. The estimated load for the period of record at the four monitoring sites downstream from I-95 ranged from 0.33 ton per day (ton/d) at the Stony Brook watershed to 0.59 ton/d at the Jordan Brook watershed. The Cl yields ranged from 0.07 ton per day per square mile (ton/d/)mi2) at Oil Mill Brook, one of the least developed watersheds, to 0.21 (ton/d)/mi2) at Jordan Brook, the watershed with the highest percentage of urban development and impervious surfaces. The median estimates of Cl load from atmospheric deposition ranged from 11 to 19 tons, and contributed 4.3 to 7.1 percent of the Cl load in streamflow from the watershed areas. A comparison of the Cl load input and output estimates indicates that less Cl is leaving the watersheds than is entering through atmospheric deposition and application of deicers. The lag time between introduction of Cl to the watershed and transport to the stream, and uncertainty in the load estimates may be the reasons for this discrepancy. In addition, estimates of direct infiltration of Cl to groundwater from atmospheric deposition, deicer applications, and septic-tank drainfields to groundwater were outside the scope of the November 2008 to September 2009 assessment. However, increased concentrations of ions were observed between upstream and downstream sites and could result from deicer appli

Meta-QTL analysis of seed iron and zinc concentration and content in common bean (Phaseolus vulgaris L.).

PubMed

Izquierdo, Paulo; Astudillo, Carolina; Blair, Matthew W; Iqbal, Asif M; Raatz, Bodo; Cichy, Karen A

2018-05-11

Twelve meta-QTL for seed Fe and Zn concentration and/or content were identified from 87 QTL originating from seven population grown in sixteen field trials. These meta-QTL include 2 specific to iron, 2 specific to zinc and 8 that co-localize for iron and zinc concentrations and/or content. Common bean (Phaseolus vulgaris L.) is the most important legume for human consumption worldwide and it is an important source of microelements, especially iron and zinc. Bean biofortification breeding programs develop new varieties with high levels of Fe and Zn targeted for countries with human micronutrient deficiencies. Biofortification efforts thus far have relied on phenotypic selection of raw seed mineral concentrations in advanced generations. While numerous quantitative trait loci (QTL) studies have been conducted to identify genomic regions associated with increased Fe and Zn concentration in seeds, these results have yet to be employed for marker-assisted breeding. The objective of this study was to conduct a meta-analysis from seven QTL studies in Andean and Middle American intra- and inter-gene pool populations to identify the regions in the genome that control the Fe and Zn levels in seeds. Two meta-QTL specific to Fe and two meta-QTL specific to Zn were identified. Additionally, eight Meta QTL that co-localized for Fe and Zn concentration and/or content were identified across seven chromosomes. The Fe and Zn shared meta-QTL could be useful candidates for marker-assisted breeding to simultaneously increase seed Fe and Zn. The physical positions for 12 individual meta-QTL were identified and within five of the meta-QTL, candidate genes were identified from six gene families that have been associated with transport of iron and zinc in plants.

Water quality of Rhode Island streams

USGS Publications Warehouse

Briggs, J.C.; Feiffer, J.S.

1986-01-01

Water quality data collected from November 1979 through September 1983 at five stream stations within Rhode Island and one in Massachusetts show that concentrations of the common constituents were low. Mean water hardness at all sites was in the ' soft ' category. Sodium concentrations were less than 20 mg/L at two sites and less than 35 mg/L at the other sites. Mean nitrogen values for the two Blackstone River sites were in the range that could cause undesirable growths of aquatic plants. Mean phosphorus values exceeded the recommended limits for protection of aquatic life at four sites. Trace-element concentrations in the water were generally low. Those trace elements which were found in concentrations near or exceeding any standard or criterion include cadmium, chromium, lead, iron, and manganese. High concentrations of several trace elements were found in the bottom materials at several sites. The bottom materials also contained pesticides and organic chemicals including aldrin, chlordane, DDD, DDE, DDT, dieldren, endosulfan , endrin, heptachlor, Mirex, and PCB. Results of trend analysis of total phosphorus, total nitrogen, and specific conductance show a downward trend in phosphorus at two sites; an upward trend in nitrogen at one site; and one downward trend and one upward trend in specific conductance. (USGS)

Environmental geochemical study of Red Mountain--an undisturbed volcanogenic massive sulfide deposit in the Bonnifield District, Alaska range, east-central Alaska: Chapter I in Recent U.S. Geological Survey studies in the Tintina Gold Province, Alaska, United States, and Yukon, Canada--results of a 5-year project

USGS Publications Warehouse

Eppinger, Robert G.; Briggs, Paul H.; Dusel-Bacon, Cynthia; Giles, Stuart A.; Gough, Larry P.; Hammarstrom, Jane M.; Hubbard, Bernard E.

2007-01-01

Water samples with the lowest pH values, highest specific conductances, and highest major- and trace-element concentrations are from springs and streams within the quartz-sericite-pyrite alteration zone. Aluminum, As, Cd, Co, Cu, Fe, Mn, Ni, Pb, Y, and particularly Zn and the REEs are all found in high concentrations, ranging across four orders of magnitude. Waters collected upstream from the alteration zone have near-neutral pH values, lower specific conductances, lower metal concentrations, and measurable alkalinities. Water samples collected downstream of the alteration zone have pH values and metal concentrations intermediate between these two extremes. Stream sediments are anomalous in Zn, Pb, S, Fe, Cu, As, Co, Sb, and Cd relative to local and regional background abundances. Red Mountain Creek and its tributaries do not support, and probably never have supported, significant megascopic faunal aquatic life.

Water quality of Tampa Bay, Florida, June 1972-May 1976

USGS Publications Warehouse

Goetz, Carole L.; Goodwin, Carl R.

1980-01-01

A comprehensive assessment of the water quality of Tampa Bay, Florida, was initiated in 1970 to provide background information to evaluate the effects of widening and deepening the ship channel to the port of Tampa. This report provides results of water-quality sampling in the bay from 1972 to 1976, prior to dredging. Measurements of temperature, dissolved oxygen, pH, turbidity, specific conductance, biochemical oxygen demand, and total organic carbon were made as well as measurements for several nutrient, metal, and pesticide parameters. Many parameters were measured at as many as three points in the vertical. These data indicate that Tampa Bay is well-mixed vertically with little density stratification. Time histories of average temperature, dissolved oxygen, pH, turbidity, specific conductance and nutrient values within four subareas of Tampa Bay are given to reveal seasonal or other trends during the period of record. Temperature, dissolved oxygen, pH, turbidity, specific conductance, nutrient, biochemical oxygen demand, total organic carbon, and metal data are also presented as areal distributions. Nutrient concentrations were generally higher in Hillsborough Bay than in other sub-areas of Tampa Bay. Biochemical oxygen demand, total organic carbon, and total organic nitrogen distribution patterns show regions of highest concentrations to be along bay shorelines near population centers. Of the metals analyzed, all were present in concentrations of less than 1 milligram per liter. (USGS)

A method for estimating radioactive cesium concentrations in cattle blood using urine samples.

PubMed

Sato, Itaru; Yamagishi, Ryoma; Sasaki, Jun; Satoh, Hiroshi; Miura, Kiyoshi; Kikuchi, Kaoru; Otani, Kumiko; Okada, Keiji

2017-12-01

In the region contaminated by the Fukushima nuclear accident, radioactive contamination of live cattle should be checked before slaughter. In this study, we establish a precise method for estimating radioactive cesium concentrations in cattle blood using urine samples. Blood and urine samples were collected from a total of 71 cattle on two farms in the 'difficult-to-return zone'. Urine 137 Cs, specific gravity, electrical conductivity, pH, sodium, potassium, calcium, and creatinine were measured and various estimation methods for blood 137 Cs were tested. The average error rate of the estimation was 54.2% without correction. Correcting for urine creatinine, specific gravity, electrical conductivity, or potassium improved the precision of the estimation. Correcting for specific gravity using the following formula gave the most precise estimate (average error rate = 16.9%): [blood 137 Cs] = [urinary 137 Cs]/([specific gravity] - 1)/329. Urine samples are faster to measure than blood samples because urine can be obtained in larger quantities and has a higher 137 Cs concentration than blood. These advantages of urine and the estimation precision demonstrated in our study, indicate that estimation of blood 137 Cs using urine samples is a practical means of monitoring radioactive contamination in live cattle. © 2017 Japanese Society of Animal Science.

Continuous water-quality monitoring and regression analysis to estimate constituent concentrations and loads in the Red River of the North at Fargo and Grand Forks, North Dakota, 2003-12

USGS Publications Warehouse

Galloway, Joel M.

2014-01-01

The Red River of the North (hereafter referred to as “Red River”) Basin is an important hydrologic region where water is a valuable resource for the region’s economy. Continuous water-quality monitors have been operated by the U.S. Geological Survey, in cooperation with the North Dakota Department of Health, Minnesota Pollution Control Agency, City of Fargo, City of Moorhead, City of Grand Forks, and City of East Grand Forks at the Red River at Fargo, North Dakota, from 2003 through 2012 and at Grand Forks, N.Dak., from 2007 through 2012. The purpose of the monitoring was to provide a better understanding of the water-quality dynamics of the Red River and provide a way to track changes in water quality. Regression equations were developed that can be used to estimate concentrations and loads for dissolved solids, sulfate, chloride, nitrate plus nitrite, total phosphorus, and suspended sediment using explanatory variables such as streamflow, specific conductance, and turbidity. Specific conductance was determined to be a significant explanatory variable for estimating dissolved solids concentrations at the Red River at Fargo and Grand Forks. The regression equations provided good relations between dissolved solid concentrations and specific conductance for the Red River at Fargo and at Grand Forks, with adjusted coefficients of determination of 0.99 and 0.98, respectively. Specific conductance, log-transformed streamflow, and a seasonal component were statistically significant explanatory variables for estimating sulfate in the Red River at Fargo and Grand Forks. Regression equations provided good relations between sulfate concentrations and the explanatory variables, with adjusted coefficients of determination of 0.94 and 0.89, respectively. For the Red River at Fargo and Grand Forks, specific conductance, streamflow, and a seasonal component were statistically significant explanatory variables for estimating chloride. For the Red River at Grand Forks, a time component also was a statistically significant explanatory variable for estimating chloride. The regression equations for chloride at the Red River at Fargo provided a fair relation between chloride concentrations and the explanatory variables, with an adjusted coefficient of determination of 0.66 and the equation for the Red River at Grand Forks provided a relatively good relation between chloride concentrations and the explanatory variables, with an adjusted coefficient of determination of 0.77. Turbidity and streamflow were statistically significant explanatory variables for estimating nitrate plus nitrite concentrations at the Red River at Fargo and turbidity was the only statistically significant explanatory variable for estimating nitrate plus nitrite concentrations at Grand Forks. The regression equation for the Red River at Fargo provided a relatively poor relation between nitrate plus nitrite concentrations, turbidity, and streamflow, with an adjusted coefficient of determination of 0.46. The regression equation for the Red River at Grand Forks provided a fair relation between nitrate plus nitrite concentrations and turbidity, with an adjusted coefficient of determination of 0.73. Some of the variability that was not explained by the equations might be attributed to different sources contributing nitrates to the stream at different times. Turbidity, streamflow, and a seasonal component were statistically significant explanatory variables for estimating total phosphorus at the Red River at Fargo and Grand Forks. The regression equation for the Red River at Fargo provided a relatively fair relation between total phosphorus concentrations, turbidity, streamflow, and season, with an adjusted coefficient of determination of 0.74. The regression equation for the Red River at Grand Forks provided a good relation between total phosphorus concentrations, turbidity, streamflow, and season, with an adjusted coefficient of determination of 0.87. For the Red River at Fargo, turbidity and streamflow were statistically significant explanatory variables for estimating suspended-sediment concentrations. For the Red River at Grand Forks, turbidity was the only statistically significant explanatory variable for estimating suspended-sediment concentration. The regression equation at the Red River at Fargo provided a good relation between suspended-sediment concentration, turbidity, and streamflow, with an adjusted coefficient of determination of 0.95. The regression equation for the Red River at Grand Forks provided a good relation between suspended-sediment concentration and turbidity, with an adjusted coefficient of determination of 0.96.

Evaluation of Measurements Collected with Multi-Parameter Continuous Water-Quality Monitors in Selected Illinois Streams, 2001-03

USGS Publications Warehouse

Groschen, George E.; King, Robin B.

2005-01-01

Eight streams, representing a wide range of environmental and water-quality conditions across Illinois, were monitored from July 2001 to October 2003 for five water-quality parameters as part of a pilot study by the U.S. Geological Survey (USGS) in cooperation with the Illinois Environmental Protection Agency (IEPA). Continuous recording multi-parameter water-quality monitors were installed to collect data on water temperature, dissolved-oxygen concentrations, specific conductivity, pH, and turbidity. The monitors were near USGS streamflow-gaging stations where stage and streamflow are continuously recorded. During the study period, the data collected for these five parameters generally met the data-quality objectives established by the USGS and IEPA at all eight stations. A similar pilot study during this period for measurement of chlorophyll concentrations failed to achieve the data-quality objectives. Of all the sensors used, the temperature sensors provided the most accurate and reliable measurements (generally within ?5 percent of a calibrated thermometer reading). Signal adjustments and calibration of all other sensors are dependent upon an accurate and precise temperature measurement. The dissolved-oxygen sensors were the next most reliable during the study and were responsive to changing conditions and accurate at all eight stations. Specific conductivity was the third most accurate and reliable measurement collected from the multi-parameter monitors. Specific conductivity at the eight stations varied widely-from less than 40 microsiemens (?S) at Rayse Creek near Waltonville to greater than 3,500 ?S at Salt Creek at Western Springs. In individual streams, specific conductivity often changed quickly (greater than 25 percent in less than 3 hours) and the sensors generally provided good to excellent record of these variations at all stations. The widest range of specific-conductivity measurements was in Salt Creek at Western Springs in the Greater Chicago metropolitan area. Unlike temperature, dissolved oxygen, and specific conductivity that have been typically measured over a wide range of historical streamflow conditions in many streams, there are few historical turbidity data and the full range of turbidity values is not well known for many streams. Because proposed regional criteria for turbidity in regional streams are based on upper 25th percentiles of concentration in reference streams, accurate determination of the distribution of turbidity in monitored streams is important. Digital data from all five sensors were recorded within each of the eight sondes deployed in the streams and in automated data recorders in the nearby streamflow-gaging houses at each station. The data recorded on each sonde were retrieved to a field laptop computer at each station visit. The feasibility of transmitting these data in near-real time to a central processing point for dissemination on the World-Wide Web was tested successfully. Data collected at all eight stations indicate that a number of factors affect the dissolved-oxygen concentration in the streams and rivers monitored. These factors include: temperature, biological activity, nutrient runoff, and weather (storm runoff). During brief periods usually in late summer, dissolved-oxygen concentrations in half or more of the eight streams and rivers monitored were below the 5 milligrams per liter minimum established by the Illinois Pollution Control Board to protect aquatic life. Because the streams monitored represent a wide range in water-quality and environmental conditions, including diffuse (non-point) runoff and wastewater-effluent contributions, this result indicates that deleterious low dissolved-oxygen concentrations during late summer may be widespread in Illinois streams.

Individual and community responses in stream mesocosms with different ionic compositions of conductivity and compared to a field-based benchmark

EPA Science Inventory

Several anthropogenic activities cause excess total dissolved solids (TDS) content and its correlate, specific conductivity, in surface waters due to increases in the major geochemical ions (e.g., Na, Ca, Cl, SO4). However, the relative concentrations of major ions varies with t...

Simultaneous Measurement of Thermophysical Properties of Tissue-Mimicking Phantoms for High Intensity Focused Ultrasound (HIFU) Exposures

NASA Astrophysics Data System (ADS)

Gao, Jing; You, Jiang; Huang, Zhihong; Cochran, Sandy; Corner, George

2012-03-01

Tissue-mimicking phantoms, including bovine serum albumin phantoms and egg white phantoms, have been developed for, and in laboratory use for, real-time visualization of high intensity focused ultrasound-induced thermal coagulative necrosis since 2001. However, until now, very few data are available concerning their thermophysical properties. In this article, a step-wise transient plane source method has been used to determine the values of thermal conductivity, thermal diffusivity, and specific heat capacity of egg white phantoms with elevated egg white concentrations (0 v/v% to 40 v/v%, by 10 v/v% interval) at room temperature (~20 °C). The measured thermophysical properties were close to previously reported values; the thermal conductivity and thermal diffusivity were linearly proportional to the egg white concentration within the investigation range, while the specific heat capacity decreased as the egg white concentration increased. Taking account of large differences between real experiment and ideal model, data variations within 20 % were accepted.

Assessment of macroinvertebrate communities in adjacent urban stream basins, Kansas City, Missouri, metropolitan area, 2007 through 2011

USGS Publications Warehouse

Christensen, Eric D.; Krempa, Heather M.

2013-01-01

Wastewater-treatment plant discharges during base flow, which elevated specific conductance and nutrient concentrations, combined sewer overflows, and nonpoint sources likely contributed to water-quality impairment and lower aquatic-life status at the Blue River Basin sites. Releases from upstream reservoirs to the Little Blue River likely decreased specific conductance, suspended-sediment, and dissolved constituent concentrations and may have benefitted water quality and aquatic life of main-stem sites. Chloride concentrations in base-flow samples, attributable to winter road salt application, had the highest correlation with the SUII (Spearman’s ρ equals 0.87), were negatively correlated with the SCI (Spearman’s ρ equals -0.53) and several pollution sensitive Ephemeroptera plus Plecoptera plus Trichoptera abundance and percent richness metrics, and were positively correlated with pollution tolerant Oligochaeta abundance and percent richness metrics. Study results show that the easily calculated SUII and the selected modeled multimetric indices are effective for comparing urban basins and for evaluation of water quality in the Kansas City metropolitan area.

Assessment of water-quality data from Long Lake National Wildlife Refuge, North Dakota--2008 through 2012

USGS Publications Warehouse

Tangen, Brian A.; Finocchiaro, Raymond G.; Gleason, Robert A.; Rabenberg, Michael J.; Dahl, Charles F.; Ell, Mike J.

2013-01-01

ong Lake National Wildlife Refuge, located in south-central North Dakota, is an important habitat for numerous migratory birds and waterfowl, including several threatened or endangered species. The refuge is distinguished by Long Lake, which is approximately 65 square kilometers and consists of four primary water management units. Water levels in the Long Lake units are maintained by low-level dikes and water-control structures, which after construction during the 1930s increased the water-storage capacity of Long Lake and reduced the frequency and volume of flushing flows downstream. The altered water regime, along with the negative precipitation:evaporation ratio of the region, may be contributing to the accumulation of water-borne chemical constituents such as salts, trace metals, and other constituents, which at certain threshold concentrations may impair aquatic plant, invertebrate, and bird communities of the refuge. The refuge’s comprehensive conservation planning process identified the need for water-quality monitoring to assess current (2013) conditions, establish comparative baselines, evaluate changes over time (trends), and support adaptive management of the wetland units. In 2008, the U.S. Geological Survey, U.S. Fish and Wildlife Service, and North Dakota Department of Health began a water-quality monitoring program at Long Lake National Wildlife Refuge to address these needs. Biweekly water-quality samples were collected for ions, trace metals, and nutrients; and in situ sensors and data loggers were installed for the continuous measurement of specific conductance and water depth. Long Lake was characterized primarily by sodium, bicarbonate, and sulfate ions. Overall results for total alkalinity and hardness were 580 and 329 milligrams per liter, respectively; thus, Long Lake is considered alkaline and classified as very hard. The mean pH and sodium adsorption ratio for Long Lake were 8.8 and 10, respectively. Total dissolved solids concentrations averaged approximately 1,750 milligrams per liter, and ranged from 117 to 39,700 milligrams per liter. Twelve of the 14 trace metals detected in the water samples had established North Dakota water-quality standards for aquatic life, and only aluminum and copper consistently exceeded these criteria. Aluminum is considered harmful to aquatic biota in acidic (pH less than 5.5) systems and most of the copper standard exceedances were collected from highly concentrated waters because of evaporation and seasonally low water levels. Concentrations for various forms of nitrogen and phosphorus generally were similar to reported regional values. Specific conductance of Long Lake varied seasonally and annually both within and among management units, with values ranging from less than 500 to nearly 40,000 microsiemens per centimeter at 25 degrees Celsius. Long Lake was characterized by consistent seasonal patterns of increasing specific conductance from spring (March and April) to fall (September and October), with levels stabilizing through the end of the sampling season (November). These seasonal patterns in specific conductance were associated with decreasing water levels throughout the summer due primarily to evaporation and continuous water releases through the Unit 1 outlet structure, which resulted in the concentration of salts. Specific conductance of each unit, along with water levels, also varied among years. Overall, specific conductance levels were greatest during the drier year of 2008 when water levels were low. Specific conductance levels were lowest during the spring of 2009 following above-average volumes of fresh water from snowmelt runoff. Comparisons of specific conductance among sample sites that were spatially distributed within each management unit suggested that spatial variability within units was low except for areas associated with local inflows. Data collected during this study revealed consistent seasonal patterns and low within-unit spatial variability of specific conductance. Based on these data results, future sample collection efforts may be reduced, as well as the number of sample locations, to limit sampling costs. Water-quality samples collected monthly or seasonally during the growing season (spring, summer, and fall) from a single representative location within each water-management unit should provide sufficient data to assess seasonal changes in water-quality over time and provide information for Long Lake management decisions.

Gain-loss study along two streams in the upper Sabine River basin, Texas; August-September 1981

USGS Publications Warehouse

Myers, Dennis R.

1983-01-01

Dissolved solids concentrations in the Sabine River, estimated from specific conductance, increased from about 120 milligrams per liter near the upstream end of the reach to about 400 milligrams per liter near the downstream end of the reach. Water with these concentrations of dissolved solids generally is suitable for most uses.

Electrokinetic removal of charged contaminant species from soil and other media using moderately conductive adsorptive materials

DOEpatents

Lindgren, Eric R.; Mattson, Earl D.

2001-01-01

Method for collecting and concentrating charged species, specifically, contaminant species in a medium, preferably soil. The method utilizes electrokinesis to drive contaminant species into and through a bed adjacent to a drive electrode. The bed comprises a moderately electrically conductive adsorbent material which is porous and is infused with water or other solvent capable of conducting electrical current. The bed material, preferably activated carbon, is easily removed and disposed of. Preferably, where activated carbon is used, after contaminant species are collected and concentrated, the mixture of activated carbon and contaminant species is removed and burned to form a stable and easily disposable waste product.

Water-quality data for selected sites on Reversed, Rush, and Alger Creeks and Gull and Silver Lakes, Mono County, California, April 1994 to March 1995

USGS Publications Warehouse

Wang, Bronwen; Rockwell, G.L.; Blodgett, J.C.

1995-01-01

Water-quality data for selected sites on Reversed, Rush, and Alger Creeks and Gull and Silver Lakes, Mono County, California, were collected from April 1994 to March 1995. Water samples were analyzed for major ions and trace elements, nutrients, methylene blue active substances, and oil and grease. Field measurements were made for discharge, specific conductance, pH, water temperature, barometric pressure, dissolved oxygen, and alkalinity. Additional data collected include vertical water profiles of specific conductance, pH, water temperature, and dissolved oxygen collected at 3.3-foot intervals for Gull and Silver Lakes; chlorophyll-a and -b concentrations and Secchi depth for Gull and Silver Lakes; sediment interstitial- water nutrient concentrations in cores from Gull Lake; and lake surface and volume of Gull and Silver Lakes.

Relating road salt to exceedances of the water quality standard for chloride in New Hampshire streams.

PubMed

Trowbridge, Philip R; Kahl, J Steve; Sassan, Dari A; Heath, Douglas L; Walsh, Edward M

2010-07-01

Six watersheds in New Hampshire were studied to determine the effects of road salt on stream water quality. Specific conductance in streams was monitored every 15 min for one year using dataloggers. Chloride concentrations were calculated from specific conductance using empirical relationships. Stream chloride concentrations were directly correlated with development in the watersheds and were inversely related to streamflow. Exceedances of the EPA water quality standard for chloride were detected in the four watersheds with the most development. The number of exceedances during a year was linearly related to the annual average concentration of chloride. Exceedances of the water quality standard were not predicted for streams with annual average concentrations less than 102 mg L(-1). Chloride was imported into three of the watersheds at rates ranging from 45 to 98 Mg Cl km(-2) yr(-1). Ninety-one percent of the chloride imported was road salt for deicing roadways and parking lots. A simple, mass balance equation was shown to predict annual average chloride concentrations from streamflow and chloride import rates to the watershed. This equation, combined with the apparent threshold for exceedances of the water quality standard, can be used for screening-level TMDLs for road salt in impaired watersheds.

Water-quality reconnaissance of the Pascagoula and Escatawpa Rivers, Jackson County, Mississippi, May 1974 to July 1978

USGS Publications Warehouse

Faye, Robert E.

1980-01-01

Short-term, water-quality reconnaissances along the downstream reaches of the Pascagoula and Escatawpa Rivers in Jackson County , Miss., indicate that stream quality during the period May 1974 to July 1978 was affected by wastewater discharges as well as river discharge and the extent of tidal intrusion. Specific conductances on the Pascagoula River ranged from less than 100 to more than 40,000 micromhos per centimeter and increased downstream. Specific conductance also increased with depth at downstram sites, indicating density stratification. Dissolved-oxygen concentrations were also affected by density stratification but were generally greater than 4.0 milligrams per liter in both rivers. Analyses of 5-day biochemical oxygen demand and nutrient concentrations indicate that oxidation of both carbonaceous and nitrogenous materials significantly affected the waste assimilative capacity of the rivers. Concentrations of pesticides and most trace elements in both the water column and the bottom sediments were zero or very small. Titanium concentrations were less than 220 micrograms per liter in the water column and 6,500 micrograms per gram in bottom sediments. Small concentrations of oil and grease, PCB's, and phenols were also detected. Fecal coliform and fecal streptococcal bacteria concentrations were generally greater in the Escatawpa River and ranged from about 10 to 18,000 colonies per 100 milliliters of water. (USGS)

Water-quality data from lakes and streams in the Grand Portage Reservation, Minnesota, 1997-98

USGS Publications Warehouse

Winterstein, Thomas A.

1999-01-01

The purpose of this report is to present the data collected by the USGS from the study during 1997-98. Water-quality data include temperature, pH, specific conductance, dissolved oxygen, alkalinity, and concentrations of major ions, nutrients, and trace metals. Lake sediment data include concentrations of trace metals and selected organic compounds.

Concentrations of chlorinated organic compounds in biota and bed sediment in streams of the lower San Joaquin River drainage, California

USGS Publications Warehouse

Brown, Larry R.

1998-01-01

Samples of resident biota and bed sediments were collected in 1992 from 18 sites on or near the floor of the San Joaquin Valley, California, for analysis of 33 organochlorine compounds. The sites were divided into five groups on the basis of physiographic region and land use. Ten compounds were detected in tissue, and 16 compounds were detected in bed sediment. The most frequently detected compound in both media was p,p'-DDE. Concentrations of total DDT (sum of o,p'- and p,p'-forms of DDD, DDE, and DDT) were statistically different among groups of sites for tissue and sediment (Kruskal-Wallis, P < 0.05). Concentrations in both media were highest in streams draining the west side of the valley. Concentrations of total DDT in tissue were significantly correlated with specific conductance, pH, and total alkalinity (P < 0.05), which are indicators of the proportion of irrigation-return flows in stream discharge. Concentrations in sediment on a dry-weight basis were not correlated with these water-quality parameters, but total-organic- carbon (TOC) normalized concentrations were significantly correlated with specific conductance and pH (P < 0.05). Regressions of the concentration of total DDT in tissue as a function of total DDT in bed sediment were significant and explained as much as 76 percent of the variance in the data. The concentration of total DDT in sediment may be related to mechanisms of soil transport to surface water with bioavailability of compounds related to the concentration of TOC in sediment.

Water quality of streams in the Red River of the North Basin, Minnesota, North Dakota, and South Dakota, 1970-2001

USGS Publications Warehouse

Tornes, Lan H.

2005-01-01

Data for the Red River of the North (Red River) Basin in Minnesota, North Dakota, and South Dakota were analyzed to determine whether the water quality of streams in the basin is adequate to meet future needs. For the Red River at Emerson, Manitoba, site, pH values, water temperatures, and dissolved-oxygen concentrations generally were within the criteria established for the protection of aquatic life. Dissolved-solids concentrations ranged from 245 to 1,100 milligrams per liter. Maximum sulfate and chloride concentrations were near, but did not exceed, the established secondary maximum contaminant level. The trace elements considered potentially harmful generally were at concentrations that were less than the established guidelines, standards, and criteria. The concentrations of lead that were detected may have occurred as a result of sample contamination.  For the Red River upstream from Emerson, Manitoba, sites, pH and other field values rarely exceeded the criteria established for the protection of aquatic life. Many constituent concentrations for the Red River below Fargo, N. site exceeded water-quality guidelines, standards, and criteria. However, the trace-element exceedances could be natural or could be related to pollution or sample contamination. Many of the tributaries in the western part of the Red River Basin had median specific-conductance values that were greater than 1,000 microsiemens per centimeter. Sulfate concentrations occasionally exceeded the established drinking-water standard. Median arsenic concentrations were 6 micrograms per liter or less, and maximum concentrations rarely exceeded the 10-microgram-per-liter drinking-water standard that is scheduled to take effect in 2006. The small concentrations of lead, mercury, and selenium that occasionally were detected may have been a result of sample contamination or other factors. The tributaries in the eastern part of the Red River Basin had median specific-conductance values that were less than 1,000 microsiemens per centimeter.  Concentrations of pesticides that were detected and that had regulatory limits were less than the cited water-quality guidelines, standards, and criteria. Concentrations of compounds that were detected generally were less than the sediment- quality standards and criteria. The data considered in this report generally provide a good baseline from which to evaluate changes in water-quality conditions. However, because many of the trace elements detected, including lead and mercury, may have been the result of sample contamination, additional data are needed to confirm that trace-element concentrations generally are low. Concentrations of major ions, including sulfate, and specific conductance may continue to approach drinking-water standards during periods of low flow because the streams, particularly those in the western part of the basin, are sustained mostly by ground-water discharge that generally has large dissolved-solids concentrations.

Effectiveness of household reverse-osmosis systems in a Western U.S. region with high arsenic in groundwater

USGS Publications Warehouse

Walker, M.; Seiler, R.L.; Meinert, M.

2008-01-01

It is well known to the public in Lahontan Valley in rural Nevada, USA, that local aquifers produce water with varied, but sometimes very high concentrations of arsenic (> 4??ppm). As a result, many residents of the area have installed household reverse-osmosis (RO) systems to produce drinking water. We examined performance of RO systems and factors associated with arsenic removal efficiency in 59 households in Lahontan Valley. The sampling results indicated that RO systems removed an average of 80.2% of arsenic from well water. In 18 of the 59 households, arsenic concentrations exceeded 10??ppb in treated water, with a maximum in treated water of 180??ppb. In 3 of the 59 households, RO treatment had little effect on specific conductance, indicating that the RO system was not working properly. Two main factors lead to arsenic levels in treated water exceeding drinking-water standards in the study area. First, arsenic concentrations were high enough in some Lahontan Valley wells that arsenic levels exceeded 10??ppb even though RO treatment removed more than 95% of the arsenic. Second, trivalent As+ 3 was the dominant arsenic species in approximately 15% of the wells, which significantly reduced treatment efficiency. Measurements of specific conductance indicated that efficiency in reducing arsenic levels did not always correlate with reductions in total dissolved solids. As a consequence, improvements in taste of the water or simple measurements of specific conductance made by technicians to test RO systems can mislead the public into assuming the water meets safety standards. Actual measurements of treated water are necessary to assure that household RO systems are reducing arsenic concentrations to safe levels, particularly in areas where groundwater has high arsenic concentrations or where As+ 3 is the dominant species. ?? 2007 Elsevier B.V. All rights reserved.

Specific conductance measurements in central and western New York streams - A retrospective characterization

USGS Publications Warehouse

Kappel, William M.; Sinclair, Gaylen J.; Reddy, James E.; Eckhardt, David A.; deVries, M. Peter; Phillips, Margaret E.

2012-01-01

U.S. Geological Survey (USGS) Data Rescue Program funds were used to recover data from paper records for 139 streamgages across central and western New York State; 6,133 different streamflow measurement forms, collected between 1970-80, contained field water-quality measurements. The water-quality data were entered, reviewed, and uploaded into the USGS National Water Information System. In total, 4,285 unique site visits were added to the database. The new values represent baseline water quality from which to measure change and will lead to a comparison of water-quality change over the last 40 years and into the future. Specific conductance was one of the measured properties and represents a simple way to determine if ambient inorganic water quality has been altered by anthropogenic (road salt runoff, wastewater discharges, or natural gas development) or natural sources. The objective of this report is to describe ambient specific conductance characteristics of surface water across the central and western part of New York. This report presents median specific conductance of stream discharge for the period 1970-80 and a description of the relation between specific conductance and concentrations of total dissolved solids (TDS) retrieved from the USGS National Water Information System (NWIS) database from 1955 to present. The data descriptions provide a baseline of surface-water specific conductance data that can used for comparison to current and future measurements in New York streams.

New insights into nitrate dynamics in a karst groundwater system gained from in situ high-frequency optical sensor measurements

USGS Publications Warehouse

Opsahl, Stephen P.; Musgrove, MaryLynn; Slattery, Richard N.

2017-01-01

Understanding nitrate dynamics in groundwater systems as a function of climatic conditions, especially during contrasting patterns of drought and wet cycles, is limited by a lack of temporal and spatial data. Nitrate sensors have the capability for making accurate, high-frequency measurements of nitrate in situ, but have not yet been evaluated for long-term use in groundwater wells. We measured in situ nitrate continuously in two groundwater monitoring wells —one rural and one urban—located in the recharge zone of a productive karst aquifer in central Texas in order to resolve changes that occur over both short-term (hourly to daily) and long-term (monthly to yearly) periods. Nitrate concentrations, measured as nitrate-nitrogen in milligrams per liter (mg/L), during drought conditions showed little or no temporal change as groundwater levels declined. During aquifer recharge, extremely rapid changes in concentration occurred at both wells as documented by hourly data. At both sites, nitrate concentrations were affected by recharging surface water as evidenced by nitrate concentrations in groundwater recharge (0.8–1.3 mg/L) that were similar to previously reported values for regional recharging streams. Groundwater nitrate concentrations responded differently at urban and rural sites during groundwater recharge. Concentrations at the rural well (approximately 1.0 mg/L) increased as a result of higher nitrate concentrations in groundwater recharge relative to ambient nitrate concentrations in groundwater, whereas concentrations at the urban well (approximately 2.7 mg/L) decreased as a result of the dilution of higher ambient nitrate concentrations relative to those in groundwater recharge. Notably, nitrate concentrations decreased to as low as 0.8 mg/L at the urban site during recharge but postrecharge concentrations exceeded 3.0 mg/L. A return to higher nitrate concentrations postrecharge indicates mobilization of a localized source of elevated nitrate within the urbanized area of the aquifer. Changes in specific conductance were observed at both sites during groundwater recharge, and a significant correlation between specific conductance and nitrate (correlation coefficient [R] = 0.455) was evident at the urban site where large (3-fold) changes in nitrate occurred. Nitrate concentrations and specific conductance measured during a depth profile indicated that the water column was generally homogeneous as expected for this karst environment, but changes were observed in the most productive zone of the aquifer that might indicate some heterogeneity within the complex network of flow paths. Resolving the timing and magnitude of changes and characterizing fine-scale vertical differences would not be possible using conventional sampling techniques. The patterns observed in situ provided new insight into the dynamic nature of nitrate in a karst groundwater system.

Ammonia Monitor

NASA Technical Reports Server (NTRS)

Sauer, Richard L. (Inventor); Akse, James R. (Inventor); Thompson, John O. (Inventor); Atwater, James E. (Inventor)

1999-01-01

Ammonia monitor and method of use are disclosed. A continuous, real-time determination of the concentration of ammonia in an aqueous process stream is possible over a wide dynamic range of concentrations. No reagents are required because pH is controlled by an in-line solid-phase base. Ammonia is selectively transported across a membrane from the process stream to an analytical stream to an analytical stream under pH control. The specific electrical conductance of the analytical stream is measured and used to determine the concentration of ammonia.

Chemistry of selected high-elevation lakes in seven national parks in the western United States

USGS Publications Warehouse

Clow, David W.; Striegl, Robert G.; Nanus, Leora; Mast, M. Alisa; Campbell, Donald H.; Krabbenhoft, David P.

2002-01-01

A chemical survey of 69 high-altitude lakes in seven national parks in the western United States was conducted during the fallof 1999; the lakes were previously sampled during the fall of 1985, as part of the Western Lake Survey. Lakes in parks in the Sierra/southern Cascades (Lassen Volcanic, Yosemite, Sequoia/Kings Canyon National Parks) and in the southern RockyMountains (Rocky Mountain National Park) were very dilute; medianspecific conductance ranged from 4.4 to 12.2 μS cm-1 andmedian alkalinity concentrations ranged from 32.2 to 72.9 μeqL-1. Specific conductances and alkalinity concentrations were substantially higher in lakes in the central and northernRocky Mountains parks (Grand Teton, Yellowstone, and GlacierNational Parks), probably due to the prevalence of more reactivebedrock types. Regional patterns in lake concentrations of NO3 and SO4 were similar to regional patterns in NO3 and SO4 concentrations in precipitation, suggestingthat the lakes are showing a response to atmospheric deposition.Concentrations of NO3 were particularly high in Rocky Mountain National Park, where some ecosystems appear to be undergoing nitrogen saturation.

An evaluation of soluble cations and anions on the conductivity and rate of flocculation of kaolins

NASA Astrophysics Data System (ADS)

Fulton, Deborah Lee

1998-10-01

The focus of this project was to learn how ionic concentrations and their contributions to electric conductivity influence the flocculation behavior of kaolin/water suspensions. Sodium silicate, calcium chloride, and magnesium sulfate were used as chemical additives. The specific surface areas, particle size distributions, and methylene blue indices for two kaolins were measured. The SSA and MBI for these kaolins indicated that they possessed inherent differences in SSA and flocculation behaviors. Rheological studies were also performed. Testing included simultaneous gelation, deflocculation, and pH tests. Viscosity, pH, temperature, and chemical additive concentrations were monitored at each point. Testing was performed at 45/55 wt% solids. Effects of additions of various levels of deflocculant and flocculant to each of the kaolin/water suspensions were studied by making several suspensions from each kaolin. The concentrations of dispersant, and flocculant levels and types were varied to produce suspensions with different chemical additive "histories," but all with similar final apparent viscosities. Slurry filtrates were analyzed for conductivity, pH, temperature, and ion concentrations of (Al3+, Fe2+,3+, Ca 2+, Mg+, Na+, SO4 2--, and Cl--). Plastic properties were calculated to determine how variations in suspension histories affected conductivities, pH, and detectable ion contents of the suspensions. These analyses were performed on starting slurries which were under-, completely-, and over-deflocculated before further additions of flocculants and deflocculant were added to tune the slurries to the final, constant, target viscosity. Results showed that rates of flocculation and conductivities increased as concentrations of ions increased. By increasing conductivity correlations with increases in flocculation occurs, which yields higher rates of buildup, or RBU [1]. This is the single most important slip control property in the whitewares industry. Shear-thinning behavior of the bodies also increased with increases in ion concentrations and conductivities. Bingham viscosities decreased as ionic concentrations increased. Brookfield buildup (BBU), plasticity index, yield stress, and pseudoplastic index generally increased as chemical additions increased. Softness and plastic behavior of the bodies increased with increasing concentrations of additive chemicals and with increasing conductivity. Calcium, sodium, and sulfate ions were primarily responsible for increasing conductivity. Calcium chloride was a more effective flocculant than magnesium sulfate.

Biosphere 2 test module experimentation program

NASA Technical Reports Server (NTRS)

Alling, Abigail; Leigh, Linda S.; Maccallum, Taber; Alvarez-Romo, Norberto

1990-01-01

The Biosphere 2 Test Module is a facility which has the capability to do either short or long term closures: five month closures with plants were conducted. Also conducted were investigations of specific problems, such as trace gas purification by bioregenerative systems by in-putting a fixed concentration of a gas and observing its uptake over time. In other Test Module experiments, the concentration of one gas was changed to observe what effects this has on other gases present or on the system. The science of biospherics which encompasses the study of closed biological systems provides an opening into the future in space as well as in the Earth's biosphere.

The relation of ground-water quality to housing density, Cape Cod, Massachusetts

USGS Publications Warehouse

Persky, J.H.

1986-01-01

Correlation of median nitrate concentration in groundwater with housing density for 18 sample areas on Cape Cod yields a Pearson correlation coefficient of 0.802, which is significant at the 95 % confidence level. In five of nine sample areas where housing density is greater than one unit/acre, nitrate concentrations exceed 5 mg of nitrate/L (the Barnstable County planning goal for nitrate) in 25% of wells. Nitrate concentrations exceed 5 mg of nitrogen/L in 25% of wells in only one of nine sample areas where housing density is less than one unit/acre. Median concentrations of sodium and iron, and median levels of pH and specific conductance, are not significantly correlated with housing density. A computer generated map of nitrate shows a positive relation between nitrate concentration and housing density on Cape Cod. However, the presence of septage- or sewage-disposal sites and fertilizer use are also important factors that affect the nitrate concentration. A map of specific conductance also shows a positive relation to housing density, but little or no relation between housing density and sodium, ammonia, pH, or iron is apparent on the maps. Chemical analyses of samples collected from 3,468 private- and public-supply wells between January 1980 and June 1984 were used to examine the extent to which housing density determines water quality on Cape Cod, an area largely unsewered and underlain by a sole source aquifer. (Author 's abstract)

Environmental setting of benchmark streams in agricultural areas of eastern Wisconsin

USGS Publications Warehouse

Rheaume, S.J.; Stewart, J.S.; Lenz, B.N.

1996-01-01

Differences in land use/land cover, and riparian vegetation and instream habitat characteristics are presented. Summaries of field measurements of water temperature, pH, specific conductance and concentrations of dissolved oxygen, total organic plus ammonia nitrogen, dissolved ammonium, nitrate plus nitrte as nitrogen, total phosphorus, dissolved orthophosphate, and atrazine are listed. Concentrations of dissolved oxygen for the sampled streams ranged from 6 A to 14.3 and met the standards set by the Wisconsin Department of Natural Resources (WDNR) for supporting fish and aquatic life. Specific conductance ranged from 98 to 753 u,Scm with values highest in RHU's 1 and 3, where streams are underlain by carbonate bedrock. Median pH did not vary greatly among the four RHU's and ranged from 6.7 to 8.8 also meeting the WDNR standards. Concentrations of total organic plus ammonia nitrogen, dissolved ammonium, total phosphorus, and dissolved orthophosphate show little variation between streams and are generally low, compared to concentrations measured in agriculturally-affected streams in the same RHU's during the same sampling period. Concentrations of the most commonly used pesticide in the study unit, atrazine, were low in all streams, and most concentrations were below trn 0.1 u,g/L detection limit. Riparian vegetation for the benchmark streams were characterized by lowland species of the native plant communities described by John T. Curtis in the "Vegetation of Wisconsin." Based on the environmental setting and water-quality information collected to date, these streams appear to show minimal adverse effects from human activity.

Effect of Euphorbia hirta plant leaf extract on immunostimulant response of Aeromonas hydrophila infected Cyprinus carpio

PubMed Central

Sukumaran, NatarajaPillai

2014-01-01

The main objective of the present study is to improve the immune power of Cyprinus carpio by using Euphorbia hirta plant leaf extract as immunostimulants. The haematological, immunological and enzymatic studies were conducted on the medicated fish infected with Aeromonas hydrophila pathogen. The results obtained from the haematological studies show that the RBC count, WBC count and haemoglobin content were increased in the infected fish at higher concentration of leaf extract. The feeds with leaf extract of Euphorbia hirta were able to stimulate the specific immune response by increasing the titre value of antibody. It was able to stimulate the antibody production only up to the 5th day, when fed with higher concentrations of (25 g and 50 g) plant leaf extract. The plant extract showed non-specific immune responses such as lysozyme activity, phagocytic ratio, NBT assay, etc. at higher concentration (50 g) and in the same concentration (50 g), the leaf extract of Euphorbia hirta significantly eliminated the pathogen in blood and kidney. It was observed that fish have survival percentage significantly at higher concentration (50 g) of Euphorbia hirta, when compared with the control. The obtained results are statistically significant at P < 0.05 and P < 0.01 levels. This research work suggests that the plant Euphorbia hirta has immunostimulant activity by stimulating both specific and non-specific immunity at higher concentrations. PMID:25405077

Movement of Potassium Ions inside KcsA in the High Concentration Regime using a Molecular Dynamics Simulation

NASA Astrophysics Data System (ADS)

Kim, Myojeong; Jo, Byeong Chul; Yoon, Hyun Jung; Wu, Sangwook; Thangappan, Jayaraman; Eun, Changsun

2018-05-01

The selectivity and conduction specificity of the KcsA channel toward potassium ions is crucial to the activity of this protein and this channel is intricately associated with several osmotic regulation and neuronal signaling processes. Despite multi-ion characteristics, the selective conduction behavior of KcsA is controlled by the size and distance specific electrostatic interaction between the selected residues and the potassium ions. The mechanism describing the movement of potassium ions in the channel and the conformational changes to KcsA that facilitate ion movement were investigated by a molecular dynamics (MD) simulation. In this study, we analyze the movement of potassium ions and water molecules at various time intervals during a 90 ns molecular dynamics simulation in the high potassium ion concentration regime and in the absence of the voltage. Examination of specific (3.6, 17.3, 43.38 and 43.44 ns) simulation periods revealed that key residues in the selectivity filter of KcsA influence the movement of potassium ions in the channel.

Water-Quality Data from Upper Klamath and Agency Lakes, Oregon, 2007-08

USGS Publications Warehouse

Kannarr, Kristofor E.; Tanner, Dwight Q.; Lindenberg, Mary K.; Wood, Tamara M.

2010-01-01

Significant Findings The U.S. Geological Survey Upper Klamath Lake water-quality monitoring program collected data from multiparameter continuous water-quality monitors, weekly water-quality samples, and meteorological stations during May-November 2007 and 2008. The results of these measurements and sample analyses are presented in this report for 29 stations on Upper Klamath Lake and 2 stations on Agency Lake, as well as quality-assurance data for the water-quality samples. Some of the significant findings from 2007 and 2008 are listed below. In 2007-08, ammonia concentrations were at or near the detection limit at all stations during the second week in June, after which they began to increase, with peak concentrations occurring from July through November. The concentration of un-ionized ammonia, which can be toxic to aquatic life, first began to increase in mid-June and peaked in July or August at most sites. Concentrations of un-ionized ammonia measured in the Upper Klamath Lake in 2007-08 did not reach concentrations that would have been potentially lethal to suckers. Samples collected for the analysis of dissolved organic carbon (DOC) late in the 2007 season showed no evidence of an increase in DOC subsequent to the breaching of the Williamson River Delta levees on October 30. In 2007-08, the lakewide daily median of dissolved oxygen concentration began to increase in early June, and peaked in mid- to late June. The lakewide daily median pH began to increase from early June and peaked in late June (2007) or early July (2008). Lakewide daily median pH slowly decreased during the rest of both seasons. The 2007 lakewide daily median specific conductance values first peaked on July 1, coincident with a peak in dissolved oxygen concentration and pH, followed by a decrease through mid-July. Specific conductance then remained relatively stable until mid-October when a sharp increase began that continued until the end of the season. Lakewide specific conductance values for 2008 steadily increased through the season to a maximum in late September. Lakewide daily median temperatures in both years began to increase during the beginning of June and peaked in July. These temperatures persisted until late August to early September when a gradual decrease occurred. In 2007-08, water-quality conditions monitored at the Agency Lake northern and southern stations were similar to those in Klamath Lake.

Aerogel volatiles concentrator and analyzer (AVCA) - Collection and concentration of trace volatile organics in aerogel for spectroscopic detection

NASA Astrophysics Data System (ADS)

Tsapin, A.; Jones, S.; Petkov, M.; Borchardt, D.; Anderson, M.

2017-03-01

A study was conducted to determine the efficacy of using silica aerogel to collect and concentrate ambient trace organics for spectroscopic analysis. Silica aerogel was exposed to atmospheres containing trace amounts of polycyclic aromatic and aliphatic hydrocarbons. The organics present were concentrated in the aerogels by factors varying from 10 to more than 1000 over the levels found in the atmospheres, depending on the specific organic present. Since silica aerogel is transparent over a wide range of optical and near infrared wavelengths, UV-induced fluorescence, Raman and infrared spectroscopies were used to detect and identify the organics collected by the aerogel. Measurements were conducted to determine the sensitivity of these spectroscopic methods for determining organics concentrated by aerogels and the effectiveness of this method for identifying systems containing multiple organic species. Polycyclic aromatic hydrocarbons (PAHs) were added to simulated Mars regolith and then vaporized by modest heating in the presence of aerogel. The aerogels adsorbed and concentrated the PAHs, which were detected by induced fluorescence and Raman and FTIR spectroscopies.

Al/ oil nanofluids inside annular tube: an experimental study on convective heat transfer and pressure drop

NASA Astrophysics Data System (ADS)

Jafarimoghaddam, Amin; Aberoumand, Sadegh; Javaherdeh, Kourosh; Arani, Ali Akbar Abbasian; Jafarimoghaddam, Reza

2018-04-01

In this work, an experimental study on nanofluid preparation stability, thermo-physical properties, heat transfer performance and friction factor of Al/ Oil nanofluids has been carried out. Electrical Explosion Wire ( E.E.W) which is one of the most reliable one-step techniques for nanofluids preparation has been used. An annular tube has been considered as the test section in which the outer tube was subject to a uniform heat flux boundary condition of about 204 W. The utilized nanofluids were prepared in three different volume concentrations of 0.011%, 0.044% and 0.171%. A wide range of parameters such as Reynolds number Prandtl number, viscosity, thermal conductivity, density, specific heat, convective heat transfer coefficient, Nusselt number and the friction factor have been studied. The experiment was conducted in relatively low Reynolds numbers of less than 160 and within a hydrodynamically fully-developed regime. According to the results, thermal conductivity, density and viscosity increased depending on the volume concentrations and working temperatures while the specific heat declined. More importantly, it was observed that convective heat transfer coefficient and Nusselt number enhanced by 28.6% and 16.4%, respectively, for the highest volume concentration. Finally, the friction factor (which plays an important role in the pumping power) was found to be increased around 18% in the volume fraction of 0.171%.

Effects of effluents from a coal-fired, electric-generating powerplant on local ground water near Hayden, Colorado

USGS Publications Warehouse

Ellis, S.R.; Mann, P.G.

1981-01-01

Data were collected at the Hayden, Colo., powerplant for about a year during 1978-79 to monitor the effects of effluent and raw-water storage ponds on the local ground water, Sage Creek, and the Yampa River. The concentration of boron in wells downgradient from the effluent ponds indicated that the ponds were leaking, increasing the average boron concentrations in the ground water to a level in excess of the standards for agricultural use of water. Water from seeps, probably the best indicators of downgradient water quality, had average concentrations of boron two times that of the Colorado Department of Health (1977) standard for agricultural use of water. Chemical analyses of water from wells and the discharge weir downgradient from the raw-water storage ponds indicated these ponds are leaking. The effect of this leakage is that the water in wells downgradient from these ponds has a lower specific conductance and a lower boron concentration than the water in wells downgradient from the effluent ponds. The concentration of trace elements in the water from the wells and the discharge weir generally declined during the study, probably because the ground water was recovering from the effects of a plume from the raw-water pond previously used for fly-ash disposal. The effluents from the Hayden powerplant lowered the specific conductance and the iron and manganese concentrations, increased the concentration of boron, and had little or no effect on the selenium concentration in Sage Creek. Sage Creek had no discernible effect on the Yampa River because the volume of water in the Yampa River was so much greater. The effluents from the powerplant also had no discernible effect on the Yampa River. (USGS)

Computational fluid dynamics modeling of Bacillus anthracis spore deposition in rabbit and human respiratory airways

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kabilan, S.; Suffield, S. R.; Recknagle, K. P.

Three-dimensional computational fluid dynamics and Lagrangian particle deposition models were developed to compare the deposition of aerosolized Bacillus anthracis spores in the respiratory airways of a human with that of the rabbit, a species commonly used in the study of anthrax disease. The respiratory airway geometries for each species were derived respectively from computed tomography (CT) and µCT images. Both models encompassed airways that extended from the external nose to the lung with a total of 272 outlets in the human model and 2878 outlets in the rabbit model. All simulations of spore deposition were conducted under transient, inhalation–exhalation breathingmore » conditions using average species-specific minute volumes. Two different exposure scenarios were modeled in the rabbit based upon experimental inhalation studies. For comparison, human simulations were conducted at the highest exposure concentration used during the rabbit experimental exposures. Results demonstrated that regional spore deposition patterns were sensitive to airway geometry and ventilation profiles. Due to the complex airway geometries in the rabbit nose, higher spore deposition efficiency was predicted in the nasal sinus compared to the human at the same air concentration of anthrax spores. In contrast, higher spore deposition was predicted in the lower conducting airways of the human compared to the rabbit lung due to differences in airway branching pattern. This information can be used to refine published and ongoing biokinetic models of inhalation anthrax spore exposures, which currently estimate deposited spore concentrations based solely upon exposure concentrations and inhaled doses that do not factor in species-specific anatomy and physiology for deposition.« less

Meta-analysis for deriving age- and gender-specific dose-response relationships between urinary cadmium concentration and {beta} {sub 2}-microglobulinuria under environmental exposure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gamo, Masashi; Ono, Kyoko; Nakanishi, Junko

2006-05-15

A meta-analysis was conducted to derive age- and gender-specific dose-response relationships between urinary cadmium (Cd) concentration and {beta} {sub 2}-microglobulinuria ({beta}2MG-uria) under environmental exposure. {beta}2MG-uria was defined by a cutoff point of 1000 {mu}g {beta} {sub 2}-microglobulin/g creatinine. We proposed a model for describing the relationships among the interindividual variabilities in urinary Cd concentration, the ratio of Cd concentrations in the target organ and in urine, and the threshold Cd concentration in the target organ. The parameters in the model were determined so that good agreement might be achieved between the prevalence rates of {beta}2MG-uria reported in the literature andmore » those estimated by the model. In this analysis, only the data from the literature on populations environmentally exposed to Cd were used. Using the model and estimated parameters, the prevalence rate of {beta}2MG-uria can be estimated for an age- and gender-specific subpopulation for which the distribution of urinary Cd concentrations is known. The maximum permissible level of urinary Cd concentration was defined as the maximum geometric mean of the urinary Cd concentration in an age- and gender-specific subpopulation that would not result in a statistically significant increase in the prevalence rate of {beta}2MG-uria. This was estimated to be approximately 3 {mu}g/g creatinine for a population in a small geographical area and approximately 2 {mu}g/g creatinine for a nationwide population.« less

Does water chemistry limit the distribution of New Zealand mud snails in Redwood National Park?

USGS Publications Warehouse

Vazquez, Ryan; Ward, Darren M.; Sepulveda, Adam

2016-01-01

New Zealand mud snails (NZMS) are exotic mollusks present in many waterways of the western United States. In 2009, NZMS were detected in Redwood Creek in Redwood National Park, CA. Although NZMS are noted for their ability to rapidly increase in abundance and colonize new areas, after more than 5 years in Redwood Creek, their distribution remains limited to a ca. 300 m reach. Recent literature suggests that low specific conductivity and environmental calcium can limit NZMS distribution. We conducted laboratory experiments, exposing NZMS collected from Redwood Creek to both natural waters and artificial treatment solutions, to determine if low conductivity and calcium concentration limit the distribution of NZMS in Redwood National Park. For natural water exposures, we held NZMS in water from their source location (conductivity 135 μS/cm, calcium 13 mg/L) or water from four other locations in the Redwood Creek watershed encompassing a range of conductivity (77–158 μS/cm) and calcium concentration (<5–13 mg/L). For exposures in treatment solutions, we manipulated both conductivity (range 20–200 μS/cm) and calcium concentration (range <5–17.5 mg/L) in a factorial design. Response variables measured included mortality and reproductive output. Adult NZMS survived for long periods (>4 months) in the lowest conductivity waters from Redwood Creek and all but the lowest-conductivity treatment solutions, regardless of calcium concentration. However, reproductive output was very low in all natural waters and all low-calcium treatment solutions. Our results suggest that water chemistry may inhibit the spread of NZMS in Redwood National Park by reducing their reproductive output.

Surface Water Geochemistry, Sediment, and Field Parameters During Snowmelt and Monsoons in the New Mexico Reach of the Animas and San Juan Rivers, 2016

NASA Astrophysics Data System (ADS)

Blake, J.; Brown, J. E.; Mast, A.

2017-12-01

Following the release of three million gallons of metals laden surface water from the Gold King Mine in August 2015, surface-water samples were collected in the New Mexico reach of the Animas and San Juan Rivers during 2016 snowmelt and in the Animas River during three 2016 monsoonal storms. These samples were evaluated for dissolved (<0.45 µm) and total (unfiltered) concentrations of trace elements including aluminum, arsenic, iron, lead, and manganese. Dissolved concentrations of aluminum, iron, and lead account for between 0.70 % and 14% of their total metal concentrations; the manganese and arsenic range of dissolved concentrations compared to total concentrations ranges from 1.2%-75%. Concentrations of total aluminum, arsenic, iron, lead, manganese increase during the rising limb of all hydrographs, suggesting a relationship with sediment concentrations, which also increase with increasing streamflow. Aluminum and iron have the highest total concentrations, 63,400 µg/L and 82,500 µg/L, respectively. Lead and arsenic total concentrations range from 0.67 to 65.5 µg/L and 0.6 to 17 µg/L, respectively. Metals such as lead and arsenic are known to adsorb to iron and aluminum particulates. During snowmelt, the relations of total aluminum and iron to total lead and arsenic are positive and linear, while during monsoonal events, the relations are polynomial. These relations may be due to the source of metals during the specific hydrologic event. Relations between discrete water quality data and continuously monitored field parameters such as turbidity and specific conductance can provide insight to changes in concentrations of the river on a finer time scale. Regression models developed for selected sites on the Animas and San Juan Rivers show that flow, turbidity and specific conductance may be useful in understanding the relationship between total metal concentrations and real-time parameters. Surrogates for suspended sediment such as hydroacoustic may also be useful, and potentially the best option in this system, for monitoring the concentration of metals in surface water. Further evaluation of the chemistry of the watershed soils and bedrock, the streambed sediments, and suspended sediments will improve understanding of the geochemical processes in the Animas and San Juan Rivers.

Modelling (18)O2 and (16)O2 unidirectional fluxes in plants. IV: role of conductance and laws of its regulation in C3 plants.

PubMed

André, Marcel J

2013-08-01

Numerous studies focus on the measurement of conductances for CO2 transfer in plants and especially on their regulatory effects on photosynthesis. Measurement accuracy is strongly dependent on the model used and on the knowledge of the flow of photochemical energy generated by light in chloroplasts. The only accurate and precise method to quantify the linear electron flux (responsible for the production of reductive energy) is the direct measurement of O2 evolution, by (18)O2 labelling and mass spectrometry. The sharing of this energy between the carboxylation (P) and the oxygenation of photorespiration (PR) depends on the plant specificity factor (Sp) and on the corresponding atmospheric concentrations of CO2 and O2 (André, 2013). The concept of plant specificity factor simplifies the equations of the model. It gives a new expression of the effect of the conductance (g) between atmosphere and chloroplasts. Its quantitative effect on photosynthesis is easy to understand because it intervenes in the ratio of the plant specificity factor (Sp) to the specificity of Rubisco (Sr). Using this 'simple' model with the data of (18)O2 experiments, the calculation of conductance variations in response to CO2 and light was carried out. The good fitting of experimental data of O2 and CO2 exchanges confirms the validity of the simple model. The calculation of conductance variation during the increase of external CO2 concentration reveals a linear law of regulation between external and internal CO2 concentrations. During CO2 variations, the effects of g regulation tend to maintain a higher level of oxygenation (PR) in expense of a better carboxylation (P). Contrary to CO2, the variation of O2 creates a negative feedback effect compatible with a stabilization of atmospheric O2. The regulation of g amplifies this result. The effect of light in combination with CO2 is more complex. Below 800μmolquantam(-2)s(-1) the ratio PR/P is maintained unchangeable in expense of carboxylation efficiency. Above that irradiance value, PR/P increases dramatically. It appears that the saturation curves of photosynthesis under high light could be simply due to the regulation by the conductance g and not by any biochemical or biophysical limitation. In conclusion, the regulatory effect of conductance operates in a way that it preserves the rate of photorespiration. This confirms a positive and protective role of photorespiration at the biochemical, whole plant and atmosphere levels. Since the effects of photorespiration are linked to the properties of Rubisco, they add new arguments for a co-evolution of plant and atmosphere, including the evolution of CO2 conductance. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Concentrations of chlorinated organic compounds in biota and bed sediment in streams of the San Joaquin Valley, California

USGS Publications Warehouse

Brown, L.R.

1997-01-01

Samples of resident biota and bed sediments were collected in 1992 from 18 sites on or near the floor of the San Joaquin Valley, California, for analysis of 33 organochlorine compounds. The sites were divided into five groups on the basis of physiographic region and land use. Ten compounds were detected in tissue, and 15 compounds were detected in bed sediment. The most frequently detected compound in both media was p,p'-DDE. Concentrations of ??DDT (sum of o,p'- and p, p' forms of DDD, DDE, and DDT) were statistically different among groups of sites for both tissue and sediment (Kruskal- Wallis, p < 0.05). Concentrations in both media were highest in streams draining the west side of the valley. Concentrations of ??DDT in tissue were significantly correlated with specific conductance, pH, and total alkalinity (p < 0.05), which are indicators of the proportion of irrigation return flows in stream discharge. Concentrations in sediment on a dry-weight basis were not correlated with these water-quality parameters, but total organic carbon (TOC) normalized concentrations were significantly correlated with specific conductance and pH (p < 0.05). Regressions of the concentration of ??DDT in tissue, as a function of ??DDT in bed sediment, were significant and explained up to 76% of the variance in the data. The concentration of ??DDT in sediment may be related to mechanisms of soil transport to surface water with bioavailability of compounds related to the concentration of TOC in sediment. The results of this study did not indicate any clear advantage to using either bed sediment or tissues in studies of organochlorine chemicals in the environment. Some guidelines for protection of fish and wildlife were exceeded. Concentrations of organochlorine chemicals in biota, and perhaps sediment, have declined from concentrations measured in the 1970s and 1980s, but remain high compared to other regions of the United States.

Evaluation of Populus and Salix continuously irrigated with landfill leachate I. Genotype-specific elemental phytoremediation.

PubMed

Zalesny, Ronald S; Bauer, Edmund O

2007-01-01

There is a need for the identification and selection of specific tree genotypes that can sequester elements from contaminated soils, with elevated rates of uptake. We irrigated Populus (DN17, DN182, DN34, NM2, NM6) and Salix (94003, 94012, S287, S566, SX61) genotypes planted in large soil-filled containers with landfill leachate or municipal water and tested for differences in inorganic element concentrations (P, K, Ca, Mg, S, Zn, B, Mn, Fe, Cu, Al, Na, and Cl) in the leaves, stems, and roots. Trees were irrigated with leachate or water during the final 12 wk of the 18-wk study. Genotype-specific uptake existed. For genera, tissue concentrations exhibited four responses. First, Populus had the greatest uptake of P, K, S, Cu, and Cl. Second, Salix exhibited the greatest uptake of Zn, B, Fe, and Al. Third, Salix had greater concentrations of Ca and Mg in leaves, while Populus had greater concentrations in stems and roots. Fourth, Populus had greater concentrations of Mn and Na in leaves and stems, while Salix had greater concentrations in roots. Populus deltoides x P. nigra clones exhibited better overall phytoremediation than the P. nigra x P. maximowiczii genotypes tested. Phytoremediation for S. purpurea clones 94003 and 94012 was generally less than for other Salix genotypes. Overall, concentrations of elements in the leaves, stems, and roots corroborated those in the plant-sciences literature. Uptake was dependent upon the specific genotype for most elements. Our results corroborated the need for further testing and selecting of specific clones for various phytoremediation needs, while providing a baseline for future researchers developing additional studies and resource managers conducting on-site remediation.

Concentrations of hormones, pharmaceuticals and other micropollutants in groundwater affected by septic systems in New England and New York

USGS Publications Warehouse

Phillips, Patrick J.; Schubert, Christopher E.; Argue, Denise M.; Fisher, Irene J.; Furlong, Edward T.; Foreman, William T.; Gray, James L.; Chalmers, Ann T.

2015-01-01

The highest micropollutant concentrations for the NY network were present in the shoreline wells and reflect groundwater that is most affected by septic system discharges. One of the shoreline wells had personal care/domestic use, pharmaceutical, and plasticizer concentrations ranging from 0.4 to 5.7 μg/L. Estradiol equivalency quotient concentrations were also highest in a shoreline well sample (3.1 ng/L). Most micropollutant concentrations increase with increasing specific conductance and total nitrogen concentrations for shoreline well samples. These findings suggest that septic systems serving institutional settings and densely populated areas in coastal settings may be locally important sources of micropollutants to adjacent aquifer and marine systems.

Continuous flow electrophoresis system experiments on shuttle flights STS-6 and STS-7

NASA Technical Reports Server (NTRS)

Snyder, Robert S.; Rhodes, Percy H.; Miller, Teresa Y.

1987-01-01

A space continuous flow electrophoresis system (CFES) was developed that would incorporate specific modifications to laboratory instruments to take advantage of weightlessness. The specific objectives were to use a model sample material at a high concentration to evaluate the continuous flow electrophoresis process in the CFES instrument and compare its separation resolution and sample throughput with related devices on Earth and to expand the basic knowledge of the limitations imposed by fluid flows and particle concentration effects on the electrophoresis process by careful design and evaluation of the space experiment. Hemoglobin and polysaccharide were selected as primary samples. The results from space show a large band spread of the high concentration of the single species of hemoglobin that was due to the mismatch of electrical conductivity between the sample and the buffer. On STS-7 the major objective was to evaluate the influence of the electrical properties of the sample constituents on the resolution of the CFES. As expected, the polystyrene latex microspheres dispersed in a solution with 3 times the electrical conductivity of the curtain buffer separated with a larger band spread than in the 2nd experiment.

Effect of low-level copper and pentachlorophenol exposure on various early life stages of Xenopus laevis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fort, D.J.; Stover, E.L.

1996-12-31

An evaluation of the effects of low-level copper and pentachlorophenol exposure on various early life stages of the South African clawed frog, Xenopus laevis, was performed using stage-specific and long-term continuous exposures. Stage-specific exposure experiments were conducted such that separate subsets of embryos and larvae from the same clutch were exposed to two toxicants, copper and pentachlorphenol, from 0 d to 4 d (standard Frog Embryo Teratogenesis Assay--Xenopus [FETAX]), 4 d to 8 d, 8 d to 12 d, and 12 d to 16 d. Results from two separate concentration-response experiments indicated that sensitivity to either toxicant increased in eachmore » successive time period. Longer-term exposure studies conducted for 60 to 75 days indicated that copper, but not pentachlorophenol induced reduction deficiency malformations of the hind limb at concentrations as low as 0.05 mg/L. Pentachlorophenol concentrations as low as 0.5 {micro}g/L inhibited tail resorption. However, copper did not adversely affect the process of tail resorption. These results indicated that studies evaluating longer-term developmental processes are important in ecological hazard evaluation.« less

Effect of chronic copper and pentachlorophenol exposure to early life stages of Xenopus laevis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fort, D.J.; Stover, E.L.

1995-12-31

An evaluation of the effects of low-level copper and pentachlorophenol exposure on various early life stages of the South African clawed frog, Xenopus laevis was performed using stage-specific and long-term continuous exposures. Stage-specific exposure experiments were conducted such that separate subsets of embryos and larvae from the same clutch were exposed to two toxicants, copper and pentachlorophenol, from 0 d to 4 d (standard Frog Embryo Teratagenesis Assay Xenopus [FETAX]), 4 d to 8 d, 8 d to 12 d, and 12 d to 16 d. Results from two separate concentration-response experiments indicated that sensitivity to either toxicant increased inmore » each successive time period. Continuous exposure studies conducted for 60 to 75 days indicated that copper, but not pentachlorophenol induced reduction deficiency malformations of the hind limb at concentrations as low as 0.05 mg/L. Pentachlorophenol concentrations as low as 0.5/{micro}g/L inhibited tail resorption. However, copper did not adversely affect the process of tail resorption. These results indicated that studies evaluating longer-term developmental processes are important in ecological hazard evaluation.« less

Use of real-time monitoring to predict concentrations of select constituents in the Menomonee River drainage basin, Southeast Wisconsin, 2008-9

USGS Publications Warehouse

Baldwin, Austin K.; Graczyk, David J.; Robertson, Dale M.; Saad, David A.; Magruder, Christopher

2012-01-01

The models to estimate chloride concentrations all used specific conductance as the explanatory variable, except for the model for the Little Menomonee River near Freistadt, which used both specific conductance and turbidity as explanatory variables. Adjusted R2 values for the chloride models ranged from 0.74 to 0.97. Models to estimate total suspended solids and total phosphorus used turbidity as the only explanatory variable. Adjusted R2 values ranged from 0.77 to 0.94 for the total suspended solids models and from 0.55 to 0.75 for the total phosphorus models. Models to estimate indicator bacteria used water temperature and turbidity as the explanatory variables, with adjusted R2 values from 0.54 to 0.69 for Escherichia coli bacteria models and from 0.54 to 0.74 for fecal coliform bacteria models. Dissolved oxygen was not used in any of the final models. These models may help managers measure the effects of land-use changes and improvement projects, establish total maximum daily loads, estimate important water-quality indicators such as bacteria concentrations, and enable informed decision making in the future.

Parametric study of the physical properties of hydrate-bearing sand, silt, and clay sediments: 1. Electromagnetic properties

USGS Publications Warehouse

Lee, J.Y.; Santamarina, J.C.; Ruppel, C.

2010-01-01

The marked decrease in bulk electrical conductivity of sediments in the presence of gas hydrates has been used to interpret borehole electrical resistivity logs and, to a lesser extent, the results of controlled source electromagnetic surveys to constrain the spatial distribution and predicted concentration of gas hydrate in natural settings. Until now, an exhaustive laboratory data set that could be used to assess the impact of gas hydrate on the electromagnetic properties of different soils (sand, silt, and clay) at different effective stress and with different saturations of hydrate has been lacking. The laboratory results reported here are obtained using a standard geotechnical cell and the hydrate-formed tetrahydrofuran (THF), a liquid that is fully miscible in water and able to produce closely controlled saturations of hydrate from dissolved phase. Both permittivity and electrical conductivity are good indicators of the volume fraction of free water in the sediment, which is in turn dependent on hydrate saturation. Permittivity in the microwave frequency range is particularly predictive of free water content since it is barely affected by ionic concentration, pore structure, and surface conduction. Electrical conductivity (or resistivity) is less reliable for constraining water content or hydrate saturation: In addition to fluid-filled porosity, other factors, such as the ionic concentration of the pore fluid and possibly other conduction effects (e.g., surface conduction in high specific surface soils having low conductivity pore fluid), also influence electrical conductivity.

An experimental study on PEO polymer electrolyte based all-solid-state supercapacitor

NASA Astrophysics Data System (ADS)

Yijing, Yin

Supercapacitors are one of the most important electrochemical energy storage and conversion devices, however low ionic conductivity of solid state polymer electrolytes and the poor accessibility of the ions to the active sites in the porous electrode will cause low performance for all-solid-state supercapacitors and will limit their application. The objective of the dissertation is to improve the performance of all-solid-state supercapactor by improving electrolyte conductivity and solving accessibility problem of the ions to the active sites. The low ionic conductivity (10-8 S/cm) of poly(ethylene oxide) (PEO) limits its application as an electrolyte. Since PEO is a semicrystal polymer and the ion conduction take place mainly in the amorphous regions of the PEO/Lithium salt complex, improvements in the percentage of amorphous phase in PEO or increasing the charge carrier concentration and mobility could increase the ionic conductivity of PEO electrolyte. Hot pressing along with the additions of different lithium salts, inorganic fillers and plasticizers were applied to improve the ionic conductivity of PEO polymer electrolytes. Four electrode methods were used to evaluate the conductivity of PEO based polymer electrolytes. Results show that adding certain lithium salts, inorganic fillers, and plasticizers could improve the ionic conductivity of PEO electrolytes up 10-4 S/cm. Further hot pressing treatment could improve the ionic conductivity of PEO electrolytes up to 10-3 S/cm. The conductivity improvement after hot pressing treatment is elucidated as that the spherulite crystal phase is convert into the fringed micelle crystal phase or the amorphous phase of PEO electrolytes. PEO electrolytes were added into active carbon as a binder and an ion conductor, so as to provide electrodes with not only ion conduction, but also the accessibility of ion to the active sites of electrodes. The NaI/I 2 mediator was added to improve the conductivity of PEO electrolyte and provide pseudocapacitance for all-solid-state supercapacitors. Impedance, cyclic voltammetry, and gavalnostatic charge/discharge measurements were conducted to evaluate the electrochemical performance of PEO polymer electrolytes based all-solid-state supercapacitors. Results demonstrate that the conductivity of PEO electrolyte could be improved to 0.1 S/cm with a mediator concentration of 50wt%. A high conductivity in the PEO electrolyte with mediator is an indication of a high electron exchange rate between the mediator and mediator. The high electron exchange rates at mediator carbon interface and between mediator and mediator are essential in order to obtain a high response rate and high power. This automatically solves the accessibility problem. With the addition of NaI/I2 mediator, the specific capacitance increased more than 30 folds, specific power increased almost 20 folds, and specific energy increased around 10 folds. Further addition of filler to the electrodes along with the mediator could double the specific capacitor and specific power of the all-solid-state supercapacitor. The stability of the corresponded supercapacitor is good within 2000 cycles.

[Effects of soil warming on specific respiration rate and non-structural carbohydrate concentration in fine roots of Chinese fir seedlings].

PubMed

Song, Tao Tao; Chen, Guang Shui; Shi, Shun Zeng; Guo, Run Quan; Zheng, Xin; Xiong, De Cheng; Chen, Wang Yuan; Chen, Ting Ting

2018-03-01

A field mesocosm experiment with Chinese fir (Cunninghamia lanceolata) seedlings was conducted in Chenda State-Owned Forest Farm, Sanming, Fujian Province. The effects of soil warming (ambient +5 ℃) on specific respiration rates and nonstructural carbohydrate (NSC) concentrations in fine roots were measured by the ingrowth core method, to reveal the belowground responses and the adaptability of Chinese fir to global warming. The results showed that soil warming caused significant changes of fine root NSC in the second year. The NSC and starch concentrations in 0-1 mm fine roots, and the NSC and sugar concentrations in 1-2 mm fine roots decreased signifi-cantly in January. The NSC, sugar and starch concentrations in 0-1 mm roots and the starch concentration in 1-2 mm roots increased in July. Soil warming had no significant effect on fine root NSC in the third year. The specific root respiration rate of the 0-1 mm roots significantly increased in July of the second year but significantly decreased in July of the third year in the warmed plots. Compared with the 0-1 mm roots, soil warming had no significant effect on the specific root respiration rate of the 1-2 mm roots. In conclusion, the responses of fine root respiration to soil warming depended on the duration of warming. Fine root respiration partly acclimated to soil warming with increasing duration of soil warming, which kept fine root NSC being relatively stable.

Species-specific control of external superoxide levels by the coral holobiont during a natural bleaching event

NASA Astrophysics Data System (ADS)

Diaz, Julia M.; Hansel, Colleen M.; Apprill, Amy; Brighi, Caterina; Zhang, Tong; Weber, Laura; McNally, Sean; Xun, Liping

2016-12-01

The reactive oxygen species superoxide (O2.-) is both beneficial and detrimental to life. Within corals, superoxide may contribute to pathogen resistance but also bleaching, the loss of essential algal symbionts. Yet, the role of superoxide in coral health and physiology is not completely understood owing to a lack of direct in situ observations. By conducting field measurements of superoxide produced by corals during a bleaching event, we show substantial species-specific variation in external superoxide levels, which reflect the balance of production and degradation processes. Extracellular superoxide concentrations are independent of light, algal symbiont abundance and bleaching status, but depend on coral species and bacterial community composition. Furthermore, coral-derived superoxide concentrations ranged from levels below bulk seawater up to ~120 nM, some of the highest superoxide concentrations observed in marine systems. Overall, these results unveil the ability of corals and/or their microbiomes to regulate superoxide in their immediate surroundings, which suggests species-specific roles of superoxide in coral health and physiology.

Estimating discharge and non-point source nitrate loading to streams from three end-member pathways using high-frequency water quality and streamflow data

NASA Astrophysics Data System (ADS)

Miller, M. P.; Tesoriero, A. J.; Hood, K.; Terziotti, S.; Wolock, D.

2017-12-01

The myriad hydrologic and biogeochemical processes taking place in watersheds occurring across space and time are integrated and reflected in the quantity and quality of water in streams and rivers. Collection of high-frequency water quality data with sensors in surface waters provides new opportunities to disentangle these processes and quantify sources and transport of water and solutes in the coupled groundwater-surface water system. A new approach for separating the streamflow hydrograph into three components was developed and coupled with high-frequency specific conductance and nitrate data to estimate time-variable watershed-scale nitrate loading from three end-member pathways - dilute quickflow, concentrated quickflow, and slowflow groundwater - to two streams in central Wisconsin. Time-variable nitrate loads from the three pathways were estimated for periods of up to two years in a groundwater-dominated and a quickflow-dominated stream, using only streamflow and in-stream water quality data. The dilute and concentrated quickflow end-members were distinguished using high-frequency specific conductance data. Results indicate that dilute quickflow contributed less than 5% of the nitrate load at both sites, whereas 89±5% of the nitrate load at the groundwater-dominated stream was from slowflow groundwater, and 84±13% of the nitrate load at the quickflow-dominated stream was from concentrated quickflow. Concentrated quickflow nitrate concentrations varied seasonally at both sites, with peak concentrations in the winter that were 2-3 times greater than minimum concentrations during the growing season. Application of this approach provides an opportunity to assess stream vulnerability to non-point source nitrate loading and expected stream responses to current or changing conditions and practices in watersheds.

Water-quality data and Escherichia coli predictions for selected karst catchments of the upper Duck River watershed in central Tennessee, 2007–10

USGS Publications Warehouse

Murphy, Jennifer C.; Farmer, James; Layton, Alice

2016-06-13

The U.S. Geological Survey, in cooperation with the Tennessee Duck River Development Agency, monitored water quality at several locations in the upper Duck River watershed between October 2007 and September 2010. Discrete water samples collected at 24 sites in the watershed were analyzed for water quality, and Escherichia coli (E. coli) and enterococci concentrations. Additional analyses, including the determination of anthropogenic-organic compounds, bacterial concentration of resuspended sediment, and bacterial-source tracking, were performed at a subset of sites. Continuous monitoring of streamflow, turbidity, and specific conductance was conducted at seven sites; a subset of sites also was monitored for water temperature and dissolved oxygen concentration. Multiple-regression models were developed to predict instantaneous E. coli concentrations and loads at sites with continuous monitoring. This data collection effort, along with the E. coli models and predictions, support analyses of the relations among land use, bacteria source and transport, and basin hydrology in the upper Duck River watershed.

Water temperature, specific conductance, pH, and dissolved-oxygen concentrations in the lower White River and the Puyallup River estuary, Washington, August-October 2002

USGS Publications Warehouse

Ebbert, James C.

2003-01-01

The U.S. Geological Survey, Washington State Department of Ecology, and Puyallup Tribe of Indians monitored water temperature, specific conductance, pH, and dissolved-oxygen concentrations in the White River at river miles 4.9 and 1.8 from August until mid-October 2002. Water diverted from the White River upstream from the monitoring sites into Lake Tapps is returned to the river at river mile 3.6 between the two sites. The same characteristics were measured in a cross section of the Puyallup River estuary at river mile 1.5 during high and low tides in September 2002. In late August, maximum daily water temperatures in the White River of 21.1°C (degrees Celsius) at river mile 4.9 and 19.6°C at river mile 1.8 exceeded the water-quality standard of 18°C at both monitoring sites. In mid-September, maximum daily water temperatures at river mile 4.9 exceeded the standard on 5 days. From August 2-25, water temperatures at both monitoring sites were similar and little or no water was discharged from Lake Tapps to the White River. Increases in water temperature at river mile 1.8 in late September and early October were caused by the mixing of warmer water discharged from Lake Tapps with cooler water in the White River.Specific conductance in the White River usually was lower at river mile 1.8 than at river mile 4.9 because of mixing with water from Lake Tapps, which has a lower specific conductance. Maximum values of pH in the White River at river mile 4.9 often exceeded the upper limit of the water-quality standard, 8.5 pH units, from early September until mid-October, when turbidity decreased. The pH standard was not exceeded at river mile 1.8. Dissolved-oxygen concentrations in the White River were often lower at river mile 1.8 than at river mile 4.9 because of mixing with water discharged from Lake Tapps, which has lower dissolved-oxygen concentrations. The lowest concentration of dissolved oxygen observed was 7.9 mg/L (milligrams per liter) at river mile 1.8. The lower limit allowed by the water-quality standard is 8 mg/L. Concentrations of dissolved oxygen measured in a cross section of the Puyallup River estuary at high tide on September 12, 2002, ranged from 9.9 to 10.2 mg/L in fresh water at the surface and from 8.1 to 8.4 mg/L in salt water near the riverbed. These values were within limits set by Washington State water-quality standards for dissolved oxygen of 8 mg/L in fresh water and 6 mg/L in marine water.

Hydrologic and water-quality data from Mountain Island Lake, North Carolina, 1994-97

USGS Publications Warehouse

Sarver, K.M.; Steiner, B.C.

1998-01-01

Continuous-record water-level gages were established at three sites on Mountain Island Lake and one site downstream from Mountain Island Dam. The water level of Mountain Island Lake is controlled by Duke Power Company releases at Cowans Ford Dam (upstream) and Mountain Island Dam (downstream). Water levels on Mountain Island Lake measured just downstream from Cowans Ford Dam fluctuated 11.15 feet during the study. Water levels just upstream from the Mountain Island Lake forebay fluctuated 6.72 feet during the study. About 3 miles downstream from Mountain Island Dam, water levels fluctuated 5.31 feet. Sampling locations included 14 sites in Mountain Island Lake, plus one downstream river site. At three sites, automated instruments recorded water temperature, dissolved-oxygen concentration, and specific conductance at 15-minute intervals throughout the study. Water temperatures recorded continuously during the study ranged from 4.2 to 35.2 degrees Celsius, and dissolved-oxygen concentrations ranged from 2.1 to 11.8 milligrams per liter. Dissolved-oxygen concentrations generally were inversely related to water temperature, with lowest dissolved-oxygen concentrations typically recorded in the summer. Specific conductance values recorded continuously during the study ranged from 33 to 89 microsiemens per centimeter; however, mean monthly values were fairly consistent throughout the study at all sites (50 to 61 microsiemens per centimeter). In addition, vertical profiles of water temperature, dissolved-oxygen concentration, specific conductance, and pH were measured at all sampling locations during 24 site visits. Water-quality constituent concentrations were determined for seven reservoir sites and the downstream river site during 17 sampling trips. Water-quality samples were routinely analyzed for biochemical oxygen demand, fecal coliform bacteria, hardness, alkalinity, total and volatile suspended solids, nutrients, total organic carbon, chlorophyll, iron, calcium, and magnesium; the samples were analyzed less frequently for trace metals, volatile organic compounds, semivolatile organic compounds, and pesticides. Maximum dissolved nitrite plus nitrate concentrations determined during the study were 0.348 milligram per liter in the mainstem sites and 2.77 milligrams per liter in the coves. Maximum total phosphorus concentrations were 0.143 milligram per liter in the mainstem sites and 0.600 milligram per liter in the coves. Fecal coliform and chlorophyll a concentrations were less than or equal to 160 colonies per 100 milliliters and 13 micrograms per liter, respectively, in all samples. Trace metals detected in at least one sample included arsenic, chromium, copper, lead, nickel, zinc, and antimony. Concentrations of all trace metals (except zinc) were 5.0 micrograms per liter or less; the maximum zinc concentration was 80 micrograms per liter. One set of bottom material samples was collected from Gar Creek and McDowell Creek for chemical analysis and analyzed for nutrients, trace metals, organochlorine pesticides, and semivolatile organic compounds. The only organochlorine pesticide identified in either sample was p,p'-DDE at an estimated concentration of 0.8 microgram per kilogram. Twenty semivolatile organic compounds, mainly polyaromatic hydrocarbons and plasticizers, were identified.

Effects of highway deicing chemicals on shallow unconsolidated aquifers in Ohio--final report

USGS Publications Warehouse

Kunze, Allison E.; Sroka, Bernard N.

2004-01-01

As a result of concerns about salt intrusion into drinking water aquifers, the effects of highway deicing chemicals on shallow aquifers were studied at eight locations in Ohio from 1988 through 2002. The study was done by the U.S. Geological Survey, in cooperation with the Ohio Department of Transportation and the Federal Highway Administration. Sites were selected along major undivided highways where drainage is by open ditches and ground-water flow is approximately perpendicular to the highway. Records of deicer application rates were kept, and apparent movement of deicing chemicals through shallow, unconsolidated aquifers was monitored by means of periodic measurements of specific conductance and concentrations of dissolved sodium, calcium, and chloride. The State routes monitored were the following: State Route (SR) 3 in Ashland County, SR 84 in Ashtabula County, SR 29 in Champaign County, SR 4 in Clark County, SR 2 in Lucas County, SR 104 in Pickaway County, SR 14 in Portage County, and SR 97 in Richland County. The study began in 1988 with background data collection, extensive literature review, and site selection. This process, including drilling of wells at numerous test sites and the eight selected sites, lasted 3 years. Routine groundwater sampling at 4- to 6-week intervals began in January 1991 and continued through September 1999. A multilevel, passive flow ground-water sampling device was constructed and used. Other conditions monitored on a regular basis included ground-water level (monitored continuously), specific conductance, air and soil temperature, precipitation,chloride concentration in soil samples, and deicing-chemical application times and rates. Evidence from water analysis, specific-conductance measurements, and surface-geophysical measurements indicates that three of the eight sites (Ashtabula County, Lucas County, and Portage County sites) were affected by direct application of deicing chemicals. Climatic data collected during the study show that cold weather, and therefore deicing-chemical application rates, varied from south to north across the State. As a consequence, only minor traces of dissolved chloride (mean, 2443 mg/L (milligrams per liter)) above background concentrations (mean, 1323 mg/L) were determined in ground-water samples from the southernmost sites (approximately 39?30' to 40? N latitudeChampaign County, Clark County, and Pickaway County). At the Ashland and Richland County sites (approximately 40?30' N latitude), dissolved-chloride concentrations increased above background concentrations only intermittently (mean background concentrations 441 mg/L, rising to a mean of 4056 mg/L in downgradient wells). At the northernmost sites (41? 30' to 42? N latitudeLucas County, Portage County, and Ashtabula County), deicing-chemical application was consistent throughout the winter, and downgradient dissolved-chloride concentrations (mean, 124345 mg/L) rarely returned to background concentrations (mean, 737 mg/L) throughout the study period. Other factors than application rate that may affect the movement of deicing chemicals through an aquifer were precipitation amounts, the types of subsurface materials, ground-water velocity and gradient, hydraulic conductivity, soil type, land use, and Ohio Department of Transportation deicing priority.

Interplay between structure and transport properties of molten salt mixtures of ZnCl2-NaCl-KCl: A molecular dynamics study.

PubMed

Manga, Venkateswara Rao; Swinteck, Nichlas; Bringuier, Stefan; Lucas, Pierre; Deymier, Pierre; Muralidharan, Krishna

2016-03-07

Molten mixtures of network-forming covalently bonded ZnCl2 and network-modifying ionically bonded NaCl and KCl salts are investigated as high-temperature heat transfer fluids for concentrating solar power plants. Specifically, using molecular dynamics simulations, the interplay between the extent of the network structure, composition, and the transport properties (viscosity, thermal conductivity, and diffusion) of ZnCl2-NaCl-KCl molten salts is characterized. The Stokes-Einstein/Eyring relationship is found to break down in these network-forming liquids at high concentrations of ZnCl2 (>63 mol. %), while the Eyring relationship is seen with increasing KCl concentration. Further, the network modification due to the addition of K ions leads to formation of non-bridging terminal Cl ions, which in turn lead to a positive temperature dependence of thermal conductivity in these melts. This new understanding of transport in these ternary liquids enables the identification of appropriate concentrations of the network formers and network modifiers to design heat transfer fluids with desired transport properties for concentrating solar power plants.

A logical starting point for developing priorities for lizard and snake ecotoxicology: a review of available data.

PubMed

Campbell, Kym Rouse; Campbell, Todd S

2002-05-01

Reptiles, specifically lizards and snakes, usually are excluded from environmental contamination studies and ecological risk assessments. This brief summary of available lizard and snake environmental contaminant data is presented to assist in the development of priorities for lizard and snake ecotoxicology. Most contaminant studies were not conducted recently, list animals found dead or dying after pesticide application, report residue concentrations after pesticide exposure, compare contaminant concentrations in animals from different areas, compare residue concentrations found in different tissues and organs, or compare changes in concentrations over time. The biological significance of the contaminant concentrations is rarely studied. A few recent studies, especially those conducted on modern pesticides, link the contaminant effects with exposure concentrations. Nondestructive sampling techniques for determining organic and inorganic contaminant concentrations in lizards and snakes recently have been developed. Studies that relate exposure, concentration, and effects of all types of environmental contaminants on lizards and snakes are needed. Because most lizards eat insects, studies on the exposure, effects, and accumulation of insecticides in lizards, and their predators, should be a top priority. Because all snakes are upper-trophic-level carnivores, studies on the accumulation and effects of contaminants that are known to bioaccumulate or biomagnify up the food chain should be the top priority.

Investigation of dioxin concentrations in the lower Roanoke River basin, North Carolina, February 26-March 7, 2001

USGS Publications Warehouse

Miller, K.F.; Walters, D.A.

2001-01-01

Dioxin is a toxic chemical that, when present in the environment, can cause cancer and birth defects in humans. Dioxin is of particular concern because concentrations of dioxin that were released into the environment many years ago remain a contributing factor to current exposure. Dioxin exposure often occurs in surface-water systems downstream from contaminated sites and is detrimental to aquatic life. For these reasons and because the U.S. Geological Survey has expertise in conducting high-volume dioxin sampling, the U.S. Environmental Protection Agency and the State of North Carolina asked the U.S. Geological Survey to collect water samples in the lower Roanoke River to be analyzed for the presence of dioxin. Water quality of the lower Roanoke River Basin in North Carolina was assessed at eight sites during February 26-March 7, 2001. Water- quality samples were collected for analysis of suspended-sediment and dioxin concentrations; high-volume (750-liter) water samples were collected for dioxin analysis. Discharge measurements were made at or near the high-volume sampling sites. Suspended-sediment sampling and water-quality measurements of specific conductance, pH, water temperature, and dissolved-oxygen concentrations made at each sampling site included multidepth measurements at two cross-section transects and hourly measurements at the point of high-volume sampling. Multidepth measurements were made near the surface, mid-depth, and near the bottom of the water column. These values were averaged for each cross section. During the sampling period, all sites sampled had dioxin concentrations above detection limits (1 part per quintillion) for both suspended and dissolved dioxin. Suspended dioxin ranged from 5.1 to 900 femtograms per liter, and dissolved dioxin values ranged from 0.31 to 41 femtograms per liter. Suspended-sediment concentrations ranged from 1.1 to 14 milligrams per liter. Specific conductance values ranges from 111 to 340 microsiemens per centimeter at 25 degrees Celsius. The range of pH values at the sampling sites was from 6.6 to 7.7. Water temperatures ranged from 8.9 to 13 degrees Celsius. Dissolved-oxygen concentrations ranged from 7.3 to 10.9 milligrams per liter.

Depth profiling of nitrogen within 15N-incorporated nano-crystalline diamond thin films

NASA Astrophysics Data System (ADS)

Garratt, E.; AlFaify, S.; Cassidy, D. P.; Dissanayake, A.; Mancini, D. C.; Ghantasala, M. K.; Kayani, A.

2013-09-01

Nano-Crystalline Diamond (NCD) thin films are a topic of recent interest due to their excellent mechanical and electrical properties. The inclusion of nitrogen is a specific interest as its presence within NCD modifies its conductive properties. The methodology adopted for the characterization of nitrogen incorporated NCD films grown on a chromium underlayer determined a correlation between the chromium and nitrogen concentrations as well as a variation in the concentration profile of elements. Additionally, the concentration of nitrogen was found to be more than three times greater for these films versus those grown on a silicon substrate.

Calcium sulphate in ammonium sulphate solution

USGS Publications Warehouse

Sullivan, E.C.

1905-01-01

Calcium sulphate, at 25?? C., is two-thirds as soluble in dilute (o.i mol per liter) and twice as soluble in concentrated (3 mois per liter) ammonium sulphate solution as in water. The specific electric conductivity of concentrated ammonium sulphate solutions is lessened by saturating with calcium sulphate. Assuming that dissociation of ammonium sulphate takes place into 2NH4?? and SO4" and of calcium sulphate into Ca and SO4" only, and that the conductivity is a measure of such dissociation, the solubility of calcium sulphate in dilute ammonium sulphate solutions is greater than required by the mass-law. The conductivity of the dilute mixtures may be accurately calculated by means of Arrhenius' principle of isohydric solutions. In the data obtained in these calculations, the concentration of non-dissociated calcium sulphate decreases with increasing ammonium sulphate. The work as a whole is additional evidence of the fact that we are not yet in possession of all the factors necessary for reconciling the mass-law to the behavior of electrolytes. The measurements above described were made in the chemical laboratory of the University of Michigan.

Hydrologic, Water-Quality, and Meteorological Data for the Cambridge, Massachusetts, Drinking-Water Source Area, Water Year 2006

USGS Publications Warehouse

Smith, Kirk P.

2008-01-01

Records of water quantity, water quality, and meteorological parameters were continuously collected from three reservoirs, two primary streams, and four subbasin tributaries in the Cambridge, Massachusetts, drinking-water source area during water year 2006 (October 2005 through September 2006). Water samples were collected during base-flow conditions and storms in the subbasins of the Cambridge Reservoir and Stony Brook Reservoir drainage areas and analyzed for dissolved calcium, sodium, chloride, and sulfate; total nitrogen and phosphorus; and polar pesticides and metabolites. These data were collected to assist watershed administrators in managing the drinking-water source area and to identify potential sources of contaminants and trends in contaminant loading to the water supply. Monthly reservoir contents for the Cambridge Reservoir varied from about 59 to 98 percent of capacity during water year 2006, while monthly reservoir contents for the Stony Brook Reservoir and the Fresh Pond Reservoir was maintained at greater than 83 and 94 percent of capacity, respectively. If water demand is assumed to be 15 million gallons per day by the city of Cambridge, the volume of water released from the Stony Brook Reservoir to the Charles River during the 2006 water year is equivalent to an annual water surplus of about 127 percent. Recorded precipitation in the source area was about 16 percent greater for the 2006 water year than for the previous water year and was between 12 and 73 percent greater than for any recorded amount since water year 2002. The monthly mean specific-conductance values for all continuously monitored stations within the drinking-water source area were generally within the range of historical data collected since water year 1997, and in many cases were less than the historical medians. The annual mean specific conductance of 738 uS/cm (microsiemens per centimeter) for water discharged from the Cambridge Reservoir was nearly identical to the annual mean specific conductance for water year 2005 which was 737 uS/cm. However, the annual mean specific conductance at Stony Brook near Route 20 in Waltham (U.S. Geological Survey (USGS) station 01104460), on the principal tributary to the Stony Brook Reservoir, and at USGS station 01104475 on a smaller tributary to the Stony Brook Reservoir were about 15 and 13 percent lower, respectively, than the previous annual mean specific conductances of 538 and 284 uS/cm, respectively for water year 2005. The annual mean specific conductance for Fresh Pond Reservoir decreased from 553 uS/cm in the 2005 water year to 514 uS/cm in the 2006 water year. Water samples were collected in nearly all of the subbasins in the Cambridge drinking-water source area and from Fresh Pond during water year 2006. Discrete water samples were collected during base-flow conditions with an antecedent dry period of at least 4 days. Composite samples, consisting of as many as 100 subsamples, were collected by automatic samplers during storms. Concentrations of most dissolved constituents were generally lower in samples of stormwater than in samples collected during base flow; however, the average concentration of total phosphorus in samples of stormwater were from 160 to 1,109 percent greater than the average concentration in water samples collected during base-flow conditions. Concentrations of total nitrogen in water samples collected during base-flow conditions and composite samples of stormwater at USGS stations 01104415, 01104460, and 01104475 were similar, but mean concentrations of total nitrogen in samples of stormwater differed by about 0.5 mg/L (milligrams per liter) from those in water samples collected during base-flow conditions at U.S. Geological Survey stations 01104433 and 01104455. In six water samples, measurements of pH were lower than the U.S. Environmental Protection Agency (USEPA) national recommended freshwater quality criteria and the USEPA secondary drinking water-standa

Concentrator enhanced solar arrays design study

NASA Technical Reports Server (NTRS)

Lott, D. R.

1978-01-01

The analysis and preliminary design of a 25 kW concentrator enhanced lightweight flexible solar array are presented. The study was organized into five major tasks: (1) assessment and specification of design requirements; (2) mechanical design; (3) electric design; (4) concentrator design; and (5) cost projection. The tasks were conducted in an iterative manner so as to best derive a baseline design selection. The objectives of the study are discussed and comparative configurations and mass data on the SEP (Solar Electric Propulsion) array design, concentrator design options and configuration/mass data on the selected concentrator enhanced solar array baseline design are presented. Design requirements supporting design analysis and detailed baseline design data are discussed. The results of the cost projection analysis and new technology are also discussed.

Deployable wireless Fresnel lens

NASA Technical Reports Server (NTRS)

Fink, Patrick W. (Inventor); Lin, Gregory Y. (Inventor); Kennedy, Timothy F. (Inventor); Chu, Andrew W. (Inventor)

2013-01-01

Apparatus and methods for enhancing the gain of a wireless signal are provided. In at least one specific embodiment, the apparatus can include a screen comprised of one or more electrically conductive regions for reflecting electromagnetic radiation and one or more non-conductive regions for permitting electromagnetic radiation therethrough. The one or more electrically conductive regions can be disposed adjacent to at least one of the one or more non-conductive regions. The apparatus can also include a support member disposed about at least a portion of the screen. The screen can be capable of collapsing by twisting the support member in opposite screw senses to form interleaved concentric sections.

Investigation of thermal conductivity and rheological properties of nanofluids containing graphene nanoplatelets

PubMed Central

2014-01-01

In the present study, stable homogeneous graphene nanoplatelet (GNP) nanofluids were prepared without any surfactant by high-power ultrasonic (probe) dispersion of GNPs in distilled water. The concentrations of nanofluids were maintained at 0.025, 0.05, 0.075, and 0.1 wt.% for three different specific surface areas of 300, 500, and 750 m2/g. Transmission electron microscopy image shows that the suspensions are homogeneous and most of the materials have been well dispersed. The stability of nanofluid was investigated using a UV-visible spectrophotometer in a time span of 600 h, and zeta potential after dispersion had been investigated to elucidate its role on dispersion characteristics. The rheological properties of GNP nanofluids approach Newtonian and non-Newtonian behaviors where viscosity decreases linearly with the rise of temperature. The thermal conductivity results show that the dispersed nanoparticles can always enhance the thermal conductivity of the base fluid, and the highest enhancement was obtained to be 27.64% in the concentration of 0.1 wt.% of GNPs with a specific surface area of 750 m2/g. Electrical conductivity of the GNP nanofluids shows a significant enhancement by dispersion of GNPs in distilled water. This novel type of nanofluids shows outstanding potential for replacements as advanced heat transfer fluids in medium temperature applications including solar collectors and heat exchanger systems. PMID:24410867

Daily and seasonal variability of pH, dissolved oxygen, temperature, and specific conductance in the Colorado River between the forebay of Glen Canyon, Dam and Lees Ferry, northeastern Arizona, 1998-99

USGS Publications Warehouse

Flynn, Marilyn E.; Hart, Robert J.; Marzolf, G. Richard; Bowser, Carl J.

2001-01-01

The productivity of the trout fishery in the tailwater reach of the Colorado River downstream from Glen Canyon Dam depends on the productivity of lower trophic levels. Photosynthesis and respiration are basic biological processes that control productivity and alter pH and oxygen concentration. During 1998?99, data were collected to aid in the documentation of short- and long-term trends in these basic ecosystem processes in the Glen Canyon reach. Dissolved-oxygen, temperature, and specific-conductance profile data were collected monthly in the forebay of Glen Canyon Dam to document the status of water chemistry in the reservoir. In addition, pH, dissolved-oxygen, temperature, and specific-conductance data were collected at five sites in the Colorado River tailwater of Glen Canyon Dam to document the daily, seasonal, and longitudinal range of variation in water chemistry that could occur annually within the Glen Canyon reach.

Specific factors for prenatal lead exposure in the border area of China.

PubMed

Kawata, Kimiko; Li, Yan; Liu, Hao; Zhang, Xiao Qin; Ushijima, Hiroshi

2006-07-01

The objectives of this study are to examine the prevalence of increased blood lead concentrations in mothers and their umbilical cords, and to identify risk factors for prenatal lead exposure in Kunming city, Yunnan province, China. The study was conducted at two obstetrics departments, and 100 peripartum women were enrolled. The mean blood lead concentrations of the mothers and the umbilical cords were 67.3microg/l and 53.1microg/l, respectively. In multiple linear regression analysis, maternal occupational exposure, maternal consumption of homemade dehydrated vegetables and maternal habitation period in Kunming city were significantly associated with an increase of umbilical cord blood lead concentration. In addition, logistic regression analysis was used to assess the association of umbilical cord blood lead concentrations that possibly have adverse effects on brain development of newborns with each potential risk factor. Maternal frequent use of tableware with color patterns inside was significantly associated with higher cord blood lead concentration in addition to the three items in the multiple linear regression analysis. These points should be considered as specific recommendations for maternal and fetal lead exposure in this city.

Characterization of Air Manganese Exposure Estimates for Residents in Two Ohio Towns

EPA Science Inventory

This study was conducted to derive receptor-specific outdoor exposure concentrations of total suspended particulate (TSP) and respirable (dae ≤1O µm) air manganese (air-Mn) for East Liverpool and Marietta (Ohio) in the absence of facility emissions data, but where long-term air m...

Preliminary appraisal of the effects of land use on water quality in stratified-drift aquifers in Connecticut

USGS Publications Warehouse

Grady, S.J.; Weaver, M.F.

1988-01-01

The stratified-drift aquifers that underlie 7.9 sq mi of the Potatuck and 12.7 sq mi of the Pomperaug River valley, CT, consist primarily of sand and gravel deposits up to 150 ft thick. Average horizontal hydraulic conductivity of the stratified drift ranges from 20 to 170 ft/day, and groundwater flows through the aquifers at an average rate of 2 to 3 ft/day. Land use in the study areas is changing from primarily undeveloped or agricultural lands to expanding residential, commercial, and light-industrial uses. Water quality data for 1923-82, that include 127 partial chemical analyses of groundwater samples from 38 wells in the two aquifers, were augmented by sampling during 1985 from 21 new stainless-steel wells for selected major inorganic constituents, trace elements, and organic chemicals. Nonparametric statistical procedures were used to compare the water quality data from four land use areas, for the two sampling periods, and between the two aquifers. Human activities associated with agricultural, residential, and industrial/commercial land uses have affected the quality of water in the stratified-drift aquifers underlying these land use areas. Statistical comparisons of water quality data between land use areas show significant differences, with the apparent relations between land use and groundwater being: (1) Median concentrations of most groundwater constituents are smallest in undeveloped areas; (2) Groundwater in agricultural areas has the largest median sulfate and total ammonia plus organic nitrogen concentrations. Agricultural areas are also characterized by groundwater with significantly greater median specific conductance, noncarbonate hardness, carbon dioxide, and magnesium concentrations relative to undeveloped areas; (3) Median concentrations of most major inorganic constituents, excluding potassium, sulfate, and total ammonia plus organic nitrogen, are greater in groundwater in residential areas than in undeveloped and agricultural areas. (4) Groundwater in industrial/commercial areas has the greatest median specific conductance, pH, carbon dioxide, calcium, magnesium, chloride bicarbonate, dissolved solids, boron, and strontium concentrations. (Author 's abstract)

Conducting polymer functionalized single-walled carbon nanotube based chemiresistive biosensor for the detection of human cardiac myoglobin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Puri, Nidhi; Department of Physics, Faculty of Natural Sciences, Jamia Millia Islamia, New Delhi 110025; Niazi, Asad

2014-10-13

We report the fabrication of a single-walled carbon nanotube (SWNT) based ultrasensitive label-free chemiresistive biosensor for the detection of human cardiac biomarker, myoglobin (Ag-cMb). Poly(pyrrole-co-pyrrolepropylic acid) with pendant carboxyl groups was electrochemically deposited on electrophoretically aligned SWNT channel, as a conducting linker, for biomolecular immobilization of highly specific cardiac myoglobin antibody. The device was characterized by scanning electron microscopy, source-drain current-voltage (I-V), and charge-transfer characteristic studies. The device exhibited a linear response with a change in conductance in SWNT channel towards the target, Ag-cMb, over the concentration range of 1.0 to 1000 ng ml{sup −1} with a sensitivity of ∼118% per decademore » with high specificity.« less

The acoustic sensor for rapid analysis of bacterial cells in the conductive suspensions.

PubMed

Borodina, I A; Zaitsev, B D; Guliy, O; Teplykh, A A; Shikhabudinov, A M

2017-11-01

The possibility of using the acoustic sensor on the basis of a two-channel delay line for rapid analysis of bacterial cells in the conductive suspensions was investigated. The dependencies of change in phase and insertion loss of output signal of the sensor on conductivity of buffer solution with various concentrations of cells due to a specific interaction "bacterial cells - mini-antibodies" for electrically open and electrically shorted channels of delay line were measured. It has been found that these changes have the most values for the electrically open channel. It has been also shown that the sensor rapidly responds to the specific interaction and the time stabilization of the phase and insertion loss of output signal is less than 10min. Copyright © 2017 Elsevier B.V. All rights reserved.

The Pueblo Incident: A Follow-Up Survey Conducted Eight Years after the Release of the USS Pueblo Crew from North Korea

DTIC Science & Technology

1978-10-01

crew members were wounded, two of them sustained serious injuries but survived. The USS Pueblo was boarded and escorted into Wonson Harbor. The 82...view that there is one specific type of laue injury resulting from incarceration in a concentration camp, these subjects displayed a broad spectrum...incarceration." Of the 188 selected 170 submitted a claim for pension because of illness of injury re- ý,ulling from concentration camp incarceration. There

Increased concentration of Pseudomonas aeruginosa and Staphylococcus sp. in small animals exposed to aerospace environments

NASA Technical Reports Server (NTRS)

Guthrie, R. K.

1976-01-01

The effects of increased concentrations of PSEUDOMONAS AERUGINOSA AND STAPHYLOCOCCUS in the total bacterial flora of small animals exposed to simulated spacecraft environments were evaluated. Tests to detect changes in infectivity, effects of antibiotic treatments, immune responses to bacterial antigens, and effectiveness of immune responses in the experimental environment were conducted. The most significant results appear to be the differences in immune responses at simulated altitudes and the production of infection in the presence of a specific antibody.

Petroleum Hydrocarbon Mixture Toxicity and a Trait Based Approach to Soil Invertebrate Species for Site Specific Risk Assessments.

PubMed

Gainer, Amy; Cousins, Mark; Hogan, Natacha; Siciliano, Steven D

2018-05-05

Although petroleum hydrocarbons (PHCs) released to the environment typically occur as mixtures, PHC remediation guidelines often reflect individual substance toxicity. It is well documented that groups of aliphatic PHCs act via the same mechanism of action, nonpolar narcosis and, theoretically, concentration addition mixture toxicity principles apply. To assess this theory, ten standardized acute and chronic soil invertebrate toxicity tests on a range of organisms (Eisenia fetida, Lumbricus terrestris, Enchytraeus crypticus, Folsomia candida, Oppia nitens and Hypoaspis aculeifer) were conducted with a refined PHC binary mixture. Reference models for concentration addition and independent action were applied to the mixture toxicity data with consideration of synergism, antagonism and dose level toxicity. Both concentration addition and independent action, without further interactions, provided the best fit with observed response to the mixture. Individual fraction effective concentration values were predicted from optimized, fitted reference models. Concentration addition provided a better estimate than independent action of individual fraction effective concentrations based on comparison with available literature and species trends observed in toxic responses to the mixture. Interspecies differences in standardized laboratory soil invertebrate species responses to PHC contaminated soil was reflected in unique traits. Diets that included soil, large body size, permeable cuticle, low lipid content, lack of ability to molt and no maternal transfer were traits linked to a sensitive survival response to PHC contaminated soil in laboratory tests. Traits linked to sensitive reproduction response in organisms tested were long life spans with small clutch sizes. By deriving single fraction toxicity endpoints considerate of mixtures, we reduce resources and time required in conducting site specific risk assessments for the protection of soil organism's exposure pathway. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Drinking-water quality and variations in water levels in the fractured crystalline-rock aquifer, west-central Jefferson County, Colorado

USGS Publications Warehouse

Hall, Dennis C.; Johnson, Carl J.

1979-01-01

In parts of Jefferson County, CO, water for domestic use from the fractured crystalline-rock aquifer contained excessive concentrations of major ions, coliform bacteria, trace elements, or radiochemicals. Based on results of analyses from 26 wells, water from 21 of the wells contained excessive concentrations of one or more constituents. Drinking water standards were exceeded for fluoride in water from 2 wells, nitrate plus nitrite in 2 wells, dissolved solids in 1 well, iron in 6 wells, manganese in 8 wells, zinc in 2 wells, coliform bacteria in 4 wells, gross alpha radiation in 11 wells and possibly 4 more, and gross beta radiation possibly in 1 well. Local variations in concentrations of 15 chemical constituents, specific conductance, and water temperature were statistically significant. Specific conductance increased significantly during 1973-75 only in the vicinity of Indian Hills. Annual range in depths to water in 11 observation wells varied from 1 to 15 feet. The shallowest water levels were recorded in late winter, usually in February. The deepest water levels occurred during summer or fall, depending on the well and the year. Three-year trends in water level changes in 6 of the 11 wells indicated decreasing water storage in the aquifer. (USGS).

Lead in Chinese villager house dust: Geographical variation and influencing factors.

PubMed

Bi, Xiangyang; Liu, Jinling; Han, Zhixuan; Yang, Wenlin

2015-12-01

House dust has been recognized as an important contributor to Pb exposure of children. Here we conducted a comprehensive study to investigate geographical variation of Pb in Chinese villager house dust. The influences of outdoor soil Pb concentrations, dates of construction, house decoration materials, heating types, and site specific pollution on Pb concentrations in house dust were evaluated. The concentrations of Pb in 477 house dust samples collected from twenty eight areas throughout China varied from 12 to 2510 mg/kg, with a median concentration of 42 mg/kg. The median Pb concentrations in different geographical areas ranged from 16 (Zhangjiakou, Hebei) to 195 mg/kg (Loudi, Hunan). No correlations were found between the house dust Pb concentrations and the age of houses, as well as house decoration materials. Whereas outdoor soil, coal combustion, and site specific pollution may be potential Pb sources. Principal component analysis (PCA) confirmed that elemental compositions of the house dust were controlled by both anthropogenic and geogenic sources. Using scanning electron microscopy (SEM), the Pb bearing particles in the house dust were also studied. Copyright © 2015 Elsevier Ltd. All rights reserved.

The precision of wet atmospheric deposition data from national atmospheric deposition program/national trends network sites determined with collocated samplers

USGS Publications Warehouse

Nilles, M.A.; Gordon, J.D.; Schroder, L.J.

1994-01-01

A collocated, wet-deposition sampler program has been operated since October 1988 by the U.S. Geological Survey to estimate the overall sampling precision of wet atmospheric deposition data collected at selected sites in the National Atmospheric Deposition Program and National Trends Network (NADP/NTN). A duplicate set of wet-deposition sampling instruments was installed adjacent to existing sampling instruments at four different NADP/NTN sites for each year of the study. Wet-deposition samples from collocated sites were collected and analysed using standard NADP/NTN procedures. Laboratory analyses included determinations of pH, specific conductance, and concentrations of major cations and anions. The estimates of precision included all variability in the data-collection system, from the point of sample collection through storage in the NADP/NTN database. Sampling precision was determined from the absolute value of differences in the analytical results for the paired samples in terms of median relative and absolute difference. The median relative difference for Mg2+, Na+, K+ and NH4+ concentration and deposition was quite variable between sites and exceeded 10% at most sites. Relative error for analytes whose concentrations typically approached laboratory method detection limits were greater than for analytes that did not typically approach detection limits. The median relative difference for SO42- and NO3- concentration, specific conductance, and sample volume at all sites was less than 7%. Precision for H+ concentration and deposition ranged from less than 10% at sites with typically high levels of H+ concentration to greater than 30% at sites with low H+ concentration. Median difference for analyte concentration and deposition was typically 1.5-2-times greater for samples collected during the winter than during other seasons at two northern sites. Likewise, the median relative difference in sample volume for winter samples was more than double the annual median relative difference at the two northern sites. Bias accounted for less than 25% of the collocated variability in analyte concentration and deposition from weekly collocated precipitation samples at most sites.A collocated, wet-deposition sampler program has been operated since OCtober 1988 by the U.S Geological Survey to estimate the overall sampling precision of wet atmospheric deposition data collected at selected sites in the National Atmospheric Deposition Program and National Trends Network (NADP/NTN). A duplicate set of wet-deposition sampling instruments was installed adjacent to existing sampling instruments four different NADP/NTN sites for each year of the study. Wet-deposition samples from collocated sites were collected and analysed using standard NADP/NTN procedures. Laboratory analyses included determinations of pH, specific conductance, and concentrations of major cations and anions. The estimates of precision included all variability in the data-collection system, from the point of sample collection through storage in the NADP/NTN database.

Sewage plume in a sand and gravel aquifer, Cape Cod, Massachusetts

USGS Publications Warehouse

LeBlanc, Denis R.

1984-01-01

Secondarily treated domestic sewage has been disposed of on surface sand beds at the sewage treatment facility at Otis Air Force Base, Massachusetts, since 1936. Infiltration of the sewage through the sand beds into the underlying unconfined sand and gravel aquifer has resulted in a plume of sewage-contaminated ground water that is 2,500 to 3,500 feet wide, 75 feet thick, and more than 11,000 feet long. The plume extends south and southwest of the sand beds in the same direction as the regional flow of ground water, and is overlain by 20 to 50 feet of ground water derived from precipitation that recharges the aquifer. The bottom of the plume generally coincides with the contact between the permeable sand and gravel and underlying finer grained sediments. The distributions in the aquifer of specific conductance, temperature, boron, chloride, sodium, phosphorus, nitrogen (total of all species), ammonia, nitrate, dissolved oxygen, and detergents are used to delineate the plume. In ground water outside the plume, the detergent concentration is less than 0.1 milligrams per liter as MBAS (methylene blue active substances), the ammonia-nitrogen concentration is less than 0.1 milligrams per liter, the boron concentration is less than 50 micrograms per liter, and specific conductance is less than 80 mircromhos per centimeter. In the center of the plume, detergent concentrations as high as 2.6 milligrams per liter as MBAS, ammonia-nitrogen concentrations as high as 20 milligrams per liter, boron concentrations as high as 400 micrograms per liter, and specific conductance as high as 405 micromhos per centimeter were measured. Chloride, sodium, and boron are transported by the southward-flowing ground water without significant retardation, and seem to be diluted only by hydrodynamic dispersion. The movement of phosphorus is greatly restricted by sorption. Phosphorus concentrations do not exceed 0.05 milligrams per liter farther than 2,500 feet from the sand beds. Detergent concentrations in the plume are highest between 3,000 and 10,000 feet from the sand beds and reflect the introduction of nonbiodegradable detergents in 1946 and the conversion to biodegradable detergents in 1964. The center of the plume as far as 5,000 feet from the sand beds contains nitrogen as ammonia, but no nitrate and no dissolved oxygen. Ammonia is gradually oxidized to nitrate between 5,000 and 8,000 feet from the sand beds, and at distances greater than 8,000 feet oxidation of ammonia is essentially complete. Ammonia also is oxidized to nitrate along the top and sides of the plume within 5,000 of the beds where the contaminated ground water mixes with uncontaminated ground water that contains up to 11 milligrams per liter dissolved oxygen.

An evaluation of methods for estimating decadal stream loads

NASA Astrophysics Data System (ADS)

Lee, Casey J.; Hirsch, Robert M.; Schwarz, Gregory E.; Holtschlag, David J.; Preston, Stephen D.; Crawford, Charles G.; Vecchia, Aldo V.

2016-11-01

Effective management of water resources requires accurate information on the mass, or load of water-quality constituents transported from upstream watersheds to downstream receiving waters. Despite this need, no single method has been shown to consistently provide accurate load estimates among different water-quality constituents, sampling sites, and sampling regimes. We evaluate the accuracy of several load estimation methods across a broad range of sampling and environmental conditions. This analysis uses random sub-samples drawn from temporally-dense data sets of total nitrogen, total phosphorus, nitrate, and suspended-sediment concentration, and includes measurements of specific conductance which was used as a surrogate for dissolved solids concentration. Methods considered include linear interpolation and ratio estimators, regression-based methods historically employed by the U.S. Geological Survey, and newer flexible techniques including Weighted Regressions on Time, Season, and Discharge (WRTDS) and a generalized non-linear additive model. No single method is identified to have the greatest accuracy across all constituents, sites, and sampling scenarios. Most methods provide accurate estimates of specific conductance (used as a surrogate for total dissolved solids or specific major ions) and total nitrogen - lower accuracy is observed for the estimation of nitrate, total phosphorus and suspended sediment loads. Methods that allow for flexibility in the relation between concentration and flow conditions, specifically Beale's ratio estimator and WRTDS, exhibit greater estimation accuracy and lower bias. Evaluation of methods across simulated sampling scenarios indicate that (1) high-flow sampling is necessary to produce accurate load estimates, (2) extrapolation of sample data through time or across more extreme flow conditions reduces load estimate accuracy, and (3) WRTDS and methods that use a Kalman filter or smoothing to correct for departures between individual modeled and observed values benefit most from more frequent water-quality sampling.

An evaluation of methods for estimating decadal stream loads

USGS Publications Warehouse

Lee, Casey; Hirsch, Robert M.; Schwarz, Gregory E.; Holtschlag, David J.; Preston, Stephen D.; Crawford, Charles G.; Vecchia, Aldo V.

2016-01-01

Effective management of water resources requires accurate information on the mass, or load of water-quality constituents transported from upstream watersheds to downstream receiving waters. Despite this need, no single method has been shown to consistently provide accurate load estimates among different water-quality constituents, sampling sites, and sampling regimes. We evaluate the accuracy of several load estimation methods across a broad range of sampling and environmental conditions. This analysis uses random sub-samples drawn from temporally-dense data sets of total nitrogen, total phosphorus, nitrate, and suspended-sediment concentration, and includes measurements of specific conductance which was used as a surrogate for dissolved solids concentration. Methods considered include linear interpolation and ratio estimators, regression-based methods historically employed by the U.S. Geological Survey, and newer flexible techniques including Weighted Regressions on Time, Season, and Discharge (WRTDS) and a generalized non-linear additive model. No single method is identified to have the greatest accuracy across all constituents, sites, and sampling scenarios. Most methods provide accurate estimates of specific conductance (used as a surrogate for total dissolved solids or specific major ions) and total nitrogen – lower accuracy is observed for the estimation of nitrate, total phosphorus and suspended sediment loads. Methods that allow for flexibility in the relation between concentration and flow conditions, specifically Beale’s ratio estimator and WRTDS, exhibit greater estimation accuracy and lower bias. Evaluation of methods across simulated sampling scenarios indicate that (1) high-flow sampling is necessary to produce accurate load estimates, (2) extrapolation of sample data through time or across more extreme flow conditions reduces load estimate accuracy, and (3) WRTDS and methods that use a Kalman filter or smoothing to correct for departures between individual modeled and observed values benefit most from more frequent water-quality sampling.

Quality of ground water in Routt County, northwestern Colorado

USGS Publications Warehouse

Covay, Kenneth J.; Tobin, R.L.

1980-01-01

Chemical and bacteriological data were collected to describe the quality of water from selected geologic units in Routt County, Colo. Calcium bicarbonate was the dominant water-chemistry type; magnesium, sodium, and sulfate frequently occurred as codominant ions. Specific conductance values ranged from 50 to 6,000 micromhos. Mean values of specific conductance, dissolved solids , and hardness from the sampled aquifers were generally greatest in waters from the older sedimentary rocks of the Lance Formation, Lewis Shale, Mesaverde Group, and Mancos Shale, and least in the ground waters from the alluvial deposits, Browns Park Formation, and the basement complex. Correlations of specific conductance with dissolved solids and specific conductance with hardness were found within specified concentration ranges. On the basis of water-quality analyses, water from the alluvial desposits, Browns Park Formation, and the basement complex generally is the most suitable for domestic uses. Chemical constituents in water from wells or springs exceeded State and Federal standards for public-water supplies or State criteria for agricultural uses were pH, arsenic, boron, chloride, iron, fluoride, manganese, nitrite plus nitrate, selenium, sulfate, or dissolved solids. Total-coliform bacteria were detected in water from 29 sites and fecal-coliform bacteria were detected in water from 6 of the 29 sites. (USGS)

Impact of urban sprawl on water quality in eastern Massachusetts, USA.

PubMed

Tu, Jun; Xia, Zong-Guo; Clarke, Keith C; Frei, Allan

2007-08-01

A study of water quality, land use, and population variations over the past three decades was conducted in eastern Massachusetts to examine the impact of urban sprawl on water quality using geographic information system and statistical analyses. Since 1970, eastern Massachusetts has experienced pronounced urban sprawl, which has a substantial impact on water quality. High spatial correlations are found between water quality indicators (especially specific conductance, dissolved ions, including Ca, Mg, Na, and Cl, and dissolved solid) and urban sprawl indicators. Urbanized watersheds with high population density, high percentage of developed land use, and low per capita developed land use tended to have high concentrations of water pollutants. The impact of urban sprawl also shows clear spatial difference between suburban areas and central cities: The central cities experienced lower increases over time in specific conductance concentration, compared to suburban and rural areas. The impact of urban sprawl on water quality is attributed to the combined effects of population and land-use change. Per capita developed land use is a very important indicator for studying the impact of urban sprawl and improving land use and watershed management, because inclusion of this indicator can better explain the temporal and spatial variations of more water quality parameters than using individual land use or/and population density.

External quality-assurance results for the National Atmospheric Deposition Program/National Trends Network during 1991

USGS Publications Warehouse

Nilles, M.A.; Gordon, J.D.; Schroder, L.J.; Paulin, C.E.

1995-01-01

The U.S. Geological Survey used four programs in 1991 to provide external quality assurance for the National Atmospheric Deposition Program/National Trends Network (NADP/NTN). An intersite-comparison program was used to evaluate onsite pH and specific-conductance determinations. The effects of routine sample handling, processing, and shipping of wet-deposition samples on analyte determinations and an estimated precision of analyte values and concentrations were evaluated in the blind-audit program. Differences between analytical results and an estimate of the analytical precision of four laboratories routinely measuring wet deposition were determined by an interlaboratory-comparison program. Overall precision estimates for the precipitation-monitoring system were determined for selected sites by a collocated-sampler program. Results of the intersite-comparison program indicated that 93 and 86 percent of the site operators met the NADP/NTN accuracy goal for pH determinations during the two intersite-comparison studies completed during 1991. The results also indicated that 96 and 97 percent of the site operators met the NADP/NTN accuracy goal for specific-conductance determinations during the two 1991 studies. The effects of routine sample handling, processing, and shipping, determined in the blind-audit program indicated significant positive bias (a=.O 1) for calcium, magnesium, sodium, potassium, chloride, nitrate, and sulfate. Significant negative bias (or=.01) was determined for hydrogen ion and specific conductance. Only ammonium determinations were not biased. A Kruskal-Wallis test indicated that there were no significant (*3t=.01) differences in analytical results from the four laboratories participating in the interlaboratory-comparison program. Results from the collocated-sampler program indicated the median relative error for cation concentration and deposition exceeded eight percent at most sites, whereas the median relative error for sample volume, sulfate, and nitrate concentration at all sites was less than four percent. The median relative error for hydrogen ion concentration and deposition ranged from 4.6 to 18.3 percent at the four sites and as indicated in previous years of the study, was inversely proportional to the acidity of the precipitation at a given site. Overall, collocated-sampling error typically was five times that of laboratory error estimates for most analytes.

Effect of organic nitrogen concentration on the efficiency of trickling filters

NASA Astrophysics Data System (ADS)

Kopeć, Łukasz; Drewnowski, Jakub; Fernandez-Morales, F. J.

2018-02-01

The study was conducted in Poland at six selected wastewater treatment plants (WWTP) based on the trickling filters Bioclere® technology. The aim of the study was to find the relationship between the influent organic nitrogen concentration and the purification efficiency expressed as effluent COD concentration. In the tests performed, the COD to BOD5 relationship was close to 2 and the ratio of BOD5 to TN was lower than 4. The research indicated that this specific chemical composition of raw wastewater causes appearance of filamentous bacteria on the surface of trickling filter filling and strongly affect the effluent quality.

Hydrologic data for the Big Spring basin, Clayton County, Iowa, water year 1991

USGS Publications Warehouse

Kalkhoff, S.J.; Kuzniar, R.L.

1994-01-01

Stream discharge, specific conductance, pH, and water temperature were monitored continuously, and monthly water-quality samples were collected at a site on Roberts Creek and at Big Spring. Nitrite plus nitrate as nitrogen concentrations in 27 samples from Roberts Creek at the point where it leaves the study area ranged from 1.8 to 22 mg/L. Herbicide concentrations in 26 samples from the Roberts Creek site ranged from less than 0.10 μg/L (micrograms per liter) to 43 μg/L. Alachlor was detected in 42 percent of the samples; atrazine in 92 percent; and cyanazine and metolachlor in 35 percent of the samples. The total suspended-sediment load discharged in Roberts Creek was about 160,000 tons. At Big Spring, the ground-water discharge point, the daily mean specific conductance ranged from 414 to 788 microsiemens per centimeter at 25 degrees Celsius, the daily median pH ranged from 6.7 to 7.1, and the daily mean water temperature ranged from 8.5 to 13.0 degrees Celsius. Concentrations of nitrite plus nitrate as nitrogen in 23 samples ranged from 4.2 to 17 mg/L. The total measured suspended-sediment discharged from Big Spring was about 17,000 tons. Alachlor was detected in 26 percent; atrazine in 100 percent; cyanazine in 26 percent, and metolachlor in 9 percent of the samples. The maximum atrazine concentration was 16 μg/L.

Structural and electrical characterization of tamarind seed polysaccharide (TSP) doped with NH4HCO2

NASA Astrophysics Data System (ADS)

Premalatha, M.; Mathavan, T.; Selvasekarapandian, S.; Selvalakshmi, S.

2018-04-01

In the modern era, development of electrochemical energy devices such as batteries, fuel cells and supercapacitors gain attention due to the deficiency of renewable energy resources. More specifically, proton conducting materials create prime interest in the development of electrochemical devices. In this regards, a novel proton conducting biopolymer electrolyte based on Tamarind Seed Polysaccharide (TSP) was synthesized with different concentration of ammonium formate (NH4HCO2). The amorphous nature of the polymer electrolytes has been identified by XRD technique. The observed ionic conductivity values reveal that the biopolymer containing 1 g TSP: 0.4 g NH4HCO2 has highest ionic conductivity 1.23×10-3 S cm-1.

Effects of water-control structures on hydrologic and water-quality characteristics in selected agricultural drainage canals in eastern North Carolina

USGS Publications Warehouse

Treece, M.W.; Jaynes, M.L.

1994-01-01

November of water into and out of tidally affected canals in eastern North Carolina was documented before and after the installation of water-control structures. Water levels in five of the canals downstream from the water-control structures were controlled primarily by water-level fluctuations in estuarine receiving waters. Water-control structures also altered upstream water levels in all canals. Water levels were lowered upstream from tide gates, but increased upstream from flashboard risers. Both types of water-control structures attenuated the release of runoff following rainfall events, but in slightly different ways. Tide gates appeared to reduce peak discharge rates associated with rainfall, and flashboard risers lengthened the duration of runoff release. Tide gates had no apparent effect on pH, dissolved oxygen, suspended-sediment, or total phosphorus concentrations downstream from the structures. Specific conductance measured from composite samples collected with automatic samples increased downstream of tide gates after installation. Median concentrations of nitrite plus nitrate nitrogen were near the minimum detection level throughout the study; however, the number of observations of concentrations exceeding 0.1 milligram per liter dropped significantly after tide gates were installed. Following tide-gate installation, instantaneous loadings of nitrite plus nitrate nitrogen were significantly reduced at one test site, but this reduction was not observed at the other test site. Loadings of other nutrient species and suspended sediment did not change at the tide-gate test sites after tide-gate installation. Specific conductance was lower in the Beaufort County canals than in the Hyde County canals. Although there was a slight increase in median values at the flashboard-riser sites, the mean and maximum values declined substantially downstream from the risers following installation. This decline of specific conductance in the canals occurred despite a large increase of specific conductance in the tidal creek. Flashboard risers had no significant effect on concentrations of dissolved oxygen, suspended sediment, total ammonia plus organic nitrogen, or phosphorus. Maximum concentrations of ammonia nitrogen were smaller at both test sites after riser installation. In addition, concentrations of nitrite plus nitrate nitrogen exceeding 1.0 milligram per liter rarely occurred at the flashboard-riser test sites following installation of the risers. Median loadings of nitrite plus nitrate nitrogen and total nitrogen decreased at one riser test site following flashboard-riser installation. Tide gates and flashboard risers were associated with reductions in concentrations and export of nitrite plus nitrate nitrogen; however, these changes should be interpreted cautiously because reductions were not observed consistently at every site. The hydrology and baseline water-quality characteristics of the two study areas differ, making comparisons of the effectiveness of the two types of water-control structures difficult to interpret. The effects of water-control structures on the hydrology of the drainage canals are more meaningful than the changes in water quality. Tide gates and flashboard risers altered the hydrologic characteristics of the drainage canals and created an environment favorable for nutrient loss or transformation. Both structures retained agricultural drainage upstream, which increased potential storage for infiltration and reduced the potential for surface runoff, sediment, and nutrient transport, and higher peak outflow rates.

40 CFR 62.15330 - What must I include in the initial report?

Code of Federal Regulations, 2014 CFR

2014-07-01

... emissions. (3) The 4-hour block or 24-hour daily arithmetic average concentration of carbon monoxide... specifications in appendix B of 40 CFR part 60 in conducting the evaluation. (e) The maximum demonstrated load of... combustion unit uses activated carbon to control dioxins/furans or mercury emissions, the average carbon feed...

Clearcutting affects stream chemistry in the White Mountains of New Hampshire

Treesearch

C. Wayne Martin; Robert S. Pierce; Gene E. Likens; F. Herbert Bormann; F. Herbert Bormann

1986-01-01

Commercial clearcutting of northern hardwood forests changed the chemistry of the streams that drained from them. By the second year after cutting, specific conductance doubled, nitrate increased tenfold, calcium tripled, and sodium, magnesium, and potassium doubled. Chloride and ammonium did not change; sulfate decreased. Concentrations of most ions returned to...

Controlled environment life support system: Growth studies with potatoes

NASA Technical Reports Server (NTRS)

Tibbitts, T. W.; Wheeler, R. M.

1986-01-01

Results of experiments conducted to maximize the productivity of potatoes grown under controlled environmental conditions are discussed. A variety of parameters is examined which affect potato growth, specifically, photoperiod, light intensity, temperature, nitrogen nutrition, carbon dioxide concentration and culture techniques. These experiments were conducted using five different cultivars, Russet Burbank, Norchip, Superior, Kennebec and Norland. To achieve high productivity, three specific objectives were explored: (1) to develop effective cultural procedures, (2) to determine the most effective photoperiod and (3) to develop a mist culture system. It is felt that the productivity obtained in this study is below the maximum that can be obtained. High irradiance levels coupled with tuber-promoting conditions such as cooler temperatures, increased CO2 levels and lowered nitrogen concentrations should allow increases in tuber production. Tuberization appears to be accelerated by short daylengths although final yields are not increased. Mist culture techniques have not yet produced fully developed tubers. The use of supporting media and alteration of the nitrogen content of the mist solution are being explored as a way to allow tubers to develop to maturity.

Water-quality parameters and benthic algal communities at selected streams in Minnesota, August 2000 - Study design, methods and data

USGS Publications Warehouse

Lee, K.E.

2002-01-01

This report describes the study design, sampling methods, and summarizes the physical, chemical, and benthic algal data for a component of the multiagency study that was designed to document diurnal water-quality measurements (specific conductance, pH, water temperature, and dissolved oxygen), benthic algal community composition and chlorophyll-a content, and primary productivity at 12 stream sites on 6 streams in Minnesota during August 2000. Specific conductance, pH, water temperature, dissolved oxygen concentrations and percent dissolved oxygen saturation measurements were made with submersible data recorders at 30 minute intervals for a period of 3-6 days during August 2000. Benthic algae collected from wood and rock substrate were identified and enumerated. Biovolume (volume of algal cells per unit area), density (number of cells per unit area), and chlorophyll-a content from benthic algae were determined. These data can be used as part of the multiagency study to develop an understanding of the relations among nutrient concentrations, algal abundance, algal community composition, and primary production and respiration processes in rivers of differing ecoregions in Minnesota.

Effects of combined drought and heavy metal stresses on xylem structure and hydraulic conductivity in red maple (Acer rubrum L.).

PubMed

de Silva, Nayana Dilini Gardiyehewa; Cholewa, Ewa; Ryser, Peter

2012-10-01

The effects of heavy metal stress, drought stress, and their combination on xylem structure in red maple (Acer rubrum) seedlings were investigated in an outdoor pot experiment. As metal-contaminated substrate, a mixture of 1.5% slag with sand was used, with Ni, Cu, Co, and Cr as the main contaminants. Plants grown on contaminated substrate had increased leaf metal concentrations. The two stresses reduced plant growth in an additive manner. The effects of metal and drought stresses on xylem characteristics were similar to each other, with a reduced proportion of xylem tissue, reduced conduit density in stems, and reduced conduit size in the roots. This resulted, in both stems and roots, in reductions in hydraulic conductance, xylem-specific conductivity, and leaf-specific conductivity. The similarity of the responses to the two stresses suggests that the plants' response to metals was actually a drought response, probably due to the reduced water uptake capacity of the metal-exposed roots. The only plant responses specific to metal stress were decreasing trends of stomatal density and chlorophyll content. In conclusion, the exposure to metals aggravates water stress in an additive manner, making the plants more vulnerable to drought.

The Quality of Water and Bottom Material in Lunga Reservoir, Virginia, September 2004 through August 2005

USGS Publications Warehouse

Lotspeich, R. Russell

2007-01-01

Lunga Reservoir is on the U.S. Marine Corps Base in Quantico, which is in the Potomac River basin and the Piedmont Physiographic Province of northern Virginia. Because of the potential use of the reservoir for scuba-diver training and public water supply in addition to current recreational activities, the U.S. Marine Corps wanted to know more about the water quality of Lunga Reservoir and how it compared to Virginia Department of Environmental Quality and Virginia State Water Control Board ambient water-quality standards. Water samples and physical properties were collected by the U.S. Geological Survey at 6 locations throughout Lunga Reservoir, and physical properties were collected at 11 additional locations in the reservoir from September 2004 through August 2005. Water samples for analysis of pesticides and bottom-material trace elements were collected once during the study at four of the sampling locations. Water temperature, dissolved-oxygen concentration, specific conductance, pH, and total chlorophyll concentration in Lunga Reservoir all had similar seasonal and spatial variations as in other lakes and reservoirs in this geographic region - thermal gradient in the summer and fall and isothermal conditions in the winter and early spring. Concentrations of water-quality indicators in Lunga Reservoir were within comparable levels of those in other reservoirs and did not violate the Virginia State Water Control Board standards for public water supplies. Water temperatures throughout Lunga Reservoir during the study period ranged from 4.4 to 30.1 degrees Celsius, well below the State Water Control Board maximum water temperature criteria of 32 degrees Celsius. Dissolved-oxygen concentrations ranged from 0.05 to 14.1 milligrams per liter throughout the reservoir during the study period, but never fell below the State Water Control Board minimum dissolved-oxygen criterion of 4.0 milligrams per liter at the surface of Lunga Reservoir. Specific conductance throughout Lunga Reservoir ranged from 29 to 173 microsiemens per centimeter at 25 degrees Celsius during the study period, with a mean specific conductance of 68 microsiemens per centimeter at 25 degrees Celsius. Measurements of pH throughout the reservoir ranged from 4.8 to 7.6 standard units. Concentrations of chemical constituents analyzed in Lunga Reservoir samples were below any State Water Control Board criteria and generally were similar in concentration to the same chemical constituents in other reservoirs in the State. Four water samples were analyzed for 54 pesticides, and none of these pesticides were above the laboratory minimum reporting level.

Pioneering Techniques to Determine Wastewater and Urban Runoff Loads in Karst Spring Systems

NASA Astrophysics Data System (ADS)

Hasenmueller, E. A.; Criss, R. E.

2010-12-01

Comparison of urban and rural springs quantifies the magnitude and sources of water quality degradation in east-central Missouri. Urban springs consistently display a suite of impairment characteristics including increases in: (1) specific conductance; (2) coliform bacteria; (3) total suspended solids (TSS); (4) nutrient concentrations including N, P, and S species; (5) B concentration; (6) heavy metal concentrations such as Cd, Cr, and Pb; and (7) temperature variability. Several dozen springs, representing a range in magnitude and recharge area land use, were sampled in and around St. Louis, MO. In addition, effluent from the Duckett Creek Treatment Plant was sampled to ascertain the chemistry of municipal waste waters in the area. Sodium perborate is a primary ingredient in bleaching agents for detergents, and therefore B is found in very high concentrations in waste waters (> 240 ppb) compared to background levels (< 20 ppb) in carbonate-hosted springs. Consequently, B provides an excellent, conservative tracer of sewage contributions to groundwater systems, and this study has shown that several urban springs comprise > 25% waste water. High B concentrations correlate well with increased nutrient contents and high E. coli and total coliform levels, which also suggest large sewage contributions to the shallow groundwater. Elevated specific conductance in these springs is primarily due to road salt contamination of these Ca-Mg-bicarbonate waters. In marked contrast to natural springs, Na and Cl can even be the dominant ions in urban springs, so they are useful indicators of urban runoff. High concentrations of Na and Cl ions persist well into late summer, confirming stable isotope models for the ~ 1 year residence time of these shallow groundwaters. Further, specific conductance, temperature, and TSS are highly variable in urban springs because of amplified throughput of storm water runoff; in fact, many detention basins directly feed into cave systems. Dissolved oxygen (DO) and pH are useful indicators of the nature of subsurface groundwater environments. In particular, springs with no known cave passage typically have low DO and pH (< 60% saturation and < 7.7, respectively), as is common in goundwaters that do not communicate with the atmosphere. However, springs draining open cave systems have higher DO and pH (60 - 90% saturation and > 7.7, respectively) due to the equilibration of DO with the overlying cave atmosphere and the degassing of carbon dioxide. This pair of parameters might provide a novel means to detect undiscovered caves.

Concentration and separation of biological organisms by ultrafiltration and dielectrophoresis

DOEpatents

Simmons, Blake A.; Hill, Vincent R.; Fintschenko, Yolanda; Cummings, Eric B.

2010-10-12

Disclosed is a method for monitoring sources of public water supply for a variety of pathogens by using a combination of ultrafiltration techniques together dielectrophoretic separation techniques. Because water-borne pathogens, whether present due to "natural" contamination or intentional introduction, would likely be present in drinking water at low concentrations when samples are collected for monitoring or outbreak investigations, an approach is needed to quickly and efficiently concentrate and separate particles such as viruses, bacteria, and parasites in large volumes of water (e.g., 100 L or more) while simultaneously reducing the sample volume to levels sufficient for detecting low concentrations of microbes (e.g., <10 mL). The technique is also designed to screen the separated microbes based on specific conductivity and size.

Thermophysical properties of Ni-containing single-phase concentrated solid solution alloys

DOE PAGES

Jin, Ke; Mu, Sai; An, Ke; ...

2016-12-27

For this research temperature dependent thermophysical properties, including specific heat capacity, lattice thermal expansion, thermal diffusivity and conductivity, have been systematically studied in Ni and eight Ni-containing single-phase face-centered-cubic concentrated solid solution alloys, at elevated temperatures up to 1273 K. The alloys have similar specific heat values of 0.4–0.5 J·g -1·K -1 at room temperature, but their temperature dependence varies greatly due to Curie and K-state transitions. The lattice, electronic, and magnetic contributions to the specific heat have been separated based on first-principles methods in NiCo, NiFe, Ni-20Cr and NiCoFeCr. The alloys have similar thermal expansion behavior, with the exceptionmore » that NiFe and NiCoFe have much lower thermal expansion coefficient in their ferromagnetic state due to magnetostriction effects. Calculations based on the quasi-harmonic approximation accurately predict the temperature dependent lattice parameter of NiCo and NiFe with < 0.2% error, but underestimated that of Ni-20Cr by 1%, compared to the values determined from neutron diffraction. In addition, all the alloys containing Cr have very similar thermal conductivity, which is much lower than that of Ni and the alloys without Cr, due to the large magnetic disorder.« less

Selection of new Kynar-based electrolytes for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Christie, Alasdair M.; Christie, Lynn; Vincent, Colin A.

New electrolyte solution compositions have been identified for use in lithium-ion batteries after gelling with an appropriate quantity of Kynar polymer. Since the Li + conducting medium is largely the liquid electrolyte component, the assessment of these solutions as suitable lithium-ion cell candidates were investigated before adding the polymer. Selected electrolyte solutions were then used in the preparation of polymer gels. The specific conductivities of Kynar-based gels were determined as a function of salt concentration and polymer concentration. Optimised self-supporting polymer films, based on mixtures of ethylene carbonate (EC), ethylmethyl carbonate (EMC) and lithium hexafluorophosphate (LiPF 6) or lithium tetrafluoroborate (LiBF 4), showed good high current density cycling performance when used as separators in coke and Li 1- xMn 2O 4 (spinel) half-cells.

A Geochemical Mass-Balance Method for Base-Flow Separation, Upper Hillsborough River Watershed, West-Central Florida, 2003-2005 and 2009

USGS Publications Warehouse

Kish, G.R.; Stringer, C.E.; Stewart, M.T.; Rains, M.C.; Torres, A.E.

2010-01-01

Geochemical mass-balance (GMB) and conductivity mass-balance (CMB) methods for hydrograph separation were used to determine the contribution of base flow to total stormflow at two sites in the upper Hillsborough River watershed in west-central Florida from 2003-2005 and at one site in 2009. The chemical and isotopic composition of streamflow and precipitation was measured during selected local and frontal low- and high-intensity storm events and compared to the geochemical and isotopic composition of groundwater. Input for the GMB method included cation, anion, and stable isotope concentrations of surface water and groundwater, whereas input for the CMB method included continuous or point-sample measurement of specific conductance. The surface water is a calcium-bicarbonate type water, which closely resembles groundwater geochemically, indicating that much of the surface water in the upper Hillsborough River basin is derived from local groundwater discharge. This discharge into the Hillsborough River at State Road 39 and at Hillsborough River State Park becomes diluted by precipitation and runoff during the wet season, but retains the calcium-bicarbonate characteristics of Upper Floridan aquifer water. Field conditions limited the application of the GMB method to low-intensity storms but the CMB method was applied to both low-intensity and high-intensity storms. The average contribution of base flow to total discharge for all storms ranged from 31 to 100 percent, whereas the contribution of base flow to total discharge during peak discharge periods ranged from less than 10 percent to 100 percent. Although calcium, magnesium, and silica were consistent markers of Upper Floridan aquifer chemistry, their use in calculating base flow by the GMB method was limited because the frequency of point data collected in this study was not sufficient to capture the complete hydrograph from pre-event base-flow to post-event base-flow concentrations. In this study, pre-event water represented somewhat diluted groundwater. Streamflow conductivity integrates the concentrations of the major ions, and the logistics of acquiring specific conductance at frequent time intervals are less complicated than data collection, sample processing, shipment, and analysis of water samples in a laboratory. The acquisition of continuous specific conductance data reduces uncertainty associated with less-frequently collected geochemical point data.

Effect of surfactants on sorption of atrazine by soil

NASA Astrophysics Data System (ADS)

Abu-Zreig, Majed; Rudra, R. P.; Dickinson, W. T.; Evans, L. J.

1999-03-01

This study investigates the effect of synthetic wastewater containing surfactants on the sorption of atrazine using an equilibrium batch technique. Laboratory experiments were conducted on three soils with two non-ionic (Rexol and Rexonic) surfactants and one anionic (Sulphonic) surfactant, specifically manufactured for the detergent industry. Four sets of experiments were conducted to examine the influence of surfactants on the equilibrium time of atrazine sorption, to explore the effect of surfactant concentration, pH and type of surfactant on the amount of atrazine sorbed and to determine sorption isotherms of atrazine in the presence of surfactants. The results indicate that the application of Sulphonic results in dramatic increase in the adsorption of atrazine on to soils, the increase being directly proportional to the concentration of the surfactant. Application of the Sulphonic surfactants with a concentration of 3000 mg/l can result in a significant increase in Kd values of atrazine for loam and sandy loam soils. On the other hand, the effect of non-ionic surfactants depends on their concentration. Generally, non-ionic surfactants can result in a slight increase in atrazine sorption at high concentration, an exception being Rexol on sandy loam soil. At low concentrations, non-ionic surfactants have shown a tendency to decrease atrazine sorption.

Hydrologic environments and water-quality characteristics at four landfills in Mecklenburg County, North Carolina, 1980-86

USGS Publications Warehouse

Cardinell, A.P.; Barnes, C.R.; Eddins, W.H.; Coble, R.W.

1989-01-01

A water-quality study was conducted during 1980-86 at four landfills in Mecklenburg County, North Carolina. Each landfill has a three-layered hydrogeologic system typical of the Piedmont, consisting of (1) the regolith; (2) a transition zone; and (3) unweathered, fractured crystalline bedrock. As much as 7.6 inches per year of rainfall enters the ground-water system and has the potential to generate leachate within landfill cells. Ground water and leachate discharge to tributaries within the landfill sites or to streams adjacent to them. Water-quality samples were collected from 53 monitoring wells and 20 surface-water sites. Samples were analyzed for selected physical and biological characteristics, major inorganic ions, nutrients, trace elements, and organic compounds. Selected indicators of water quality, including specific conductance; hardness; and concentrations of chloride, manganese, dissolved solids, total organic carbon, and specific organic compounds were analyzed to determine the effects of each landfill on ground- and surface-water quality. Increases in concentrations of inorganic constituents above background levels were detected in ground water downgradient of the landfills. The increases were generally greatest in samples from wells in close proximity to the older landfill cells. In general, the increases in concentrations in downgradient wells were greater for calcium, magnesium, and chloride than for other major ions. Manganese exhibited the largest relative increase in concentration between upgradient and downgradient wells of any constituent, and manganese concentration data were effective in defining areas with extensive anaerobic biological activity. Differences between upgradient and downgradient concentrations of total organic carbon and specific organic compounds generally were not as apparent. The most frequently identified organic contaminants were the herbicides 2,4-D and 2,4,5-T. Chlorofluoromethanes were identified in three of four ground-water samples analyzed for volatile organic compounds. Landfills affected the water quality of several smaller streams but did not noticeably affect larger ones. Apparent effects on water quality were greatest at the oldest landfill, located on Statesville Road, where waste is in cells that are partly below the water table.

Evaluation of chemical data from selected sites in the Surface-Water Ambient Monitoring Program (SWAMP) in Florida

USGS Publications Warehouse

Katz, B.G.; Collins, J.J.

1998-01-01

A cooperative study between the Florida Department of Environmental Protection (FDEP) and the U.S. Geological Survey was conducted to assess the integrity of selected water-quality data collected at 150 sites in the FDEP Surface-Water Ambient Monitoring Program (SWAMP) in Florida. The assessment included determining the consistency of the water-quality data collected statewide, including commonality of monitoring procedures and analytes, screening of the gross validity of a chemical analysis, and quality assurance and quality control (QA/QC) procedures. Four tests were used to screen data at selected SWAMP sites to estimate the gross validity of selected chemical data: (1) the ratio of dissolved solids (in milligrams per liter) to specific conductance (in microsiemens per centimeter); (2) the ratio of total cations (in milliequivalents per liter) multiplied by 100 to specific conductance (in microsiemens per centimeter); (3) the ratio of total anions (in milliequivalents per liter) multiplied by 100 to specific conductance (in microsiemens per centimeter); and (4) the ionic charge-balance error. Although the results of the four screening tests indicate that the chemical data generally are quite reliable, the extremely small number of samples (less than 5 percent of the total number of samples) with sufficient chemical information to run the tests may not provide a representative indication of the analytical accuracy of all laboratories in the program. In addition to the four screening tests, unusually low or high values were flagged for field and laboratory pH (less than 4.0 and greater than 9.0) and specific conductance (less than 10 and greater than 10,000 microsiemens per centimeter). The numbers of flagged data were less than 1 percent of the 19,937 water samples with pH values and less than 0.6 percent of the 16,553 water samples with specific conductance values. Thirty-four agencies responded to a detailed questionnaire that was sent to more than 60 agencies involved in the collection and analysis of surface-water-quality data for SWAMP. The purpose of the survey was to evaluate quality assurance methods and consistency of methods statewide. Information was compiled and summarized on monitoring network design, data review and upload procedures, laboratory and field sampling methods, and data practices. Currently, most agencies that responded to the survey follow FDEP-approved QA/QC protocol for sampling and have quality assurance practices for recording and reporting data. Also, most agencies responded that calibration procedures were followed in the laboratory for analysis of data, but no responses were given about the specific procedures. Approximately 50 percent of the respondents indicated that laboratory analysis methods have changed over time. With so many laboratories involved in analyzing samples for SWAMP, it is difficult to compare water quality from one site to another due to different reporting conventions for chemical constituents and different analytical methods over time. Most agencies responded that calibration methods are followed in the field, but no specific details were provided. Grab samples are the most common method of collection. Other data screening procedures are necessary to further evaluate the validity of chemical data collected at SWAMP sites. High variability in the concentration of targeted constituents may signal analytical problems, but more likely changes in concentration are related to hydrologic conditions. This underscores the need for accurate measurements of discharge, lake stage, tidal stage at the time of sampling so that changes in constituent concentrations can be properly evaluated and fluxes (loads) of nutrients or metals, for example, can be calculated and compared over time.

Hydrogeology of the Socorro and La Jencia basins, Socorro County, New Mexico

USGS Publications Warehouse

Anderholm, Scott K.

1987-01-01

The Socorro and La Jencia Basins are located in central Socorro County, New Mexico. The principal aquifer system in the Socorro and La Jencia Basins consists of, in descending order, the shallow aquifer, the Popotosa confining bed, and the Popotosa aquifer. The minor aquifer systems, which are dominant along the basin margins, are the Socorro volcanics aquifer system and the Mesozoic-Paleozoic aquifer system. On the east side of the Socorro Basin, water enters the principal aquifer system from the Mesozoic-Paleozoic aquifer system. On the west side of the Socorro Basin, groundwater flows from the principal aquifer system in La Jencia Basin eastward to the principal aquifer system in the Socorro Basin. The volume of this flow is limited by the permeability of the minor aquifer systems and the Popotosa confining bed. A water budget indicates that if no change in groundwater storage occurs in the Socorro Basin, groundwater inflow to the basin is about 53,000 acre-feet per year greater than groundwater outflow. Dissolution of gypsum, calcite, and dolomite seems to control water quality in the Mesozoic-Paleozoic aquifer. Water with a chloride concentration of as much as 1,000 milligrams per liter and a specific conductance of as much as 6,700 microsiemens per centimeter at 25 C is present in the northern and southern parts of the Socorro Basin. These large chloride concentrations may indicate upward movement of water from deeper in the basin in these areas. The water with the large chloride concentration in the southern part of the basin also may be caused by leakage of geothermal waters along the Capitan Lineament. In the central part of the Socorro Basin, infiltration of excess irrigation water and inflow of groundwater from the basin margins control water quality. In this area, specific conductance generally is less than 1,000 microsiemens per centimeter. Water in La Jencia Basin generally is of the calcium sodium bicarbonate type with specific conductance less than 500 microsiemens per centimeter. (USGS)

Effects of highway deicing chemicals on shallow unconsolidated aquifers in Ohio, interim report, 1988-93

USGS Publications Warehouse

Jones, A.L.; Sroka, B.N.

1997-01-01

Effects of the application of highway deicing chemicals during winter months on ground- water quality are being studied by the U.S. Geological Survey in cooperation with the Ohio Department of Transportation and the Federal Highway Administration. Eight sites throughout the State were selected along major undivided highways where drainage is by open ditches and ground-water flow is approximately perpendicular to the highway. At these sites, records of deicer application rates are being kept and apparent movement of deicing chemicals through shallow, unconsolidated aquifers is being monitored by means of periodic measurements of specific con ductance and concentrations of dissolved sodium, calcium, and chloride. The counties and corre sponding sections of state routes being monitored are the following: State Route (SR) 3 in Ashland County, SR 84 in Ashtabula County, SR 29 in Champaign County, SR 4 in Clark County, SR 2 in Lucas County, SR 104 in Pickaway County, SR 14 in Portage County, and SR 97 in Richland County. The study began in January 1988 with background data collection, extensive literature review, and site selection. This process, including drilling of wells at the eight selected sites, lasted 3 years. Routine ground-water sampling at 4- to 6-week intervals began in January 1991. A relatively new type of multilevel, passive flow ground-water sampling device was constructed and used. Other conditions monitored on a regular basis included ground-water level (monitored con tinuously), specific conductance, air and soil temperature, precipitation, chloride concentration in soil samples, ground conductivity, and deicing chemical application times and rates. For the interim reporting period, water samples were collected from January 1991 through September 1993. Evidence from water analysis, specific conductance measurements, and surface geophysical measurements indicates that four of the eight sites (Ashtabula County, Lucas County, Portage County, and Richland County sites) are potentially affected by direct application of deic ing chemicals. Climatic data from the period January 1991 through September 1993 show that cold weather, and therefore deicing chemical application rates, varied widely across the State. As a consequence, only minor traces of dissolved chloride above background concentrations (mean, 12-25 mg/L) were determined in ground-water samples from the Pickaway County, Clark County, and Champaign County sites. At the Ashland and Richland County sites, dissolved chlo ride concentrations increased above background concentrations (from the upgradient well, pre sumably unaffected by road salt) only intermittently (mean background concentrations of 3-25 mg/L, rising to a mean of 49-77 mg/L). For the interim reporting period, the mean dissolved chloride concentration for all downgradient wells was about 2 times the background concentra tion (25mg/L) at the Ashland County site (50 mg/L) and 14 times the background concentration (3 mg/L) at the Richland County site (40 mg/L). At the Lucas County, Portage County, and Ash tabula County sites, deicing-chemical application was consistent throughout the winter, and downgradient dissolved chloride concentrations rarely returned to background concentrations (mean 6-32 mg/L) throughout the period. For the interim reporting period, the mean dissolved chloride concentration for all downgradient wells was about 3 times the background concentra tion at the Lucas County site (92 mg/L), 72 times the background concentration at the Portage County site (432 mg/L, 2 downgradient wells), and 21 times the background concentration at the Ashtabula County site (279 mg/L). Other factors that may affect the movement of deicing chemicals through the aquifer were examined, such as precipitation amounts; the types of subsurface materials; ground-water velocity and gradient; hydraulic conductivity; soil type; land use; and ODOT deicing priority. A final report is planned for 2001 afte

Epilithic diatom communities of selected streams from the Lerma-Chapala Basin, Central Mexico, with the description of two new species

PubMed Central

Mora, Demetrio; Carmona, Javier; Jahn, Regine; Zimmermann, Jonas; Abarca, Nélida

2017-01-01

Abstract The Lerma-Chapala Basin, in Central Mexico, is geologically heterogeneous, climatically diverse and boasts high biodiversity, lying within two Biodiversity Hotspots, namely Mesoamerica and the Madrean Pine–Oak Woodlands. Epilithon and water samples were collected in the basin from 14 sampling sites three times each, two sampling campaigns during the rainy season and one in the dry season. A total of 274 infrageneric taxa in 48 genera were recorded. The taxonomic composition observed was dominated by taxa from the genera Nitzschia, Gomphonema, Pinnularia, Navicula, Sellaphora and Eunotia. About a third of the taxa found could not be identified to the species level. From those unidentified morphodemes, two are described as new species, namely Brachysira altepetlensis and Sellaphora queretana. Furthermore, Eolimna rhombica is transferred to Sellaphora. Canonical Correspondence Analysis (CCA) revealed that specific conductivity and pH were the main environmental factors driving the community composition observed. Three groups of samples were identified after the CCA: 1) characterized by acidic waters and low conductivity; 2) with circumneutral waters, low specific conductivity and high temperature and phosphorous concentrations; and 3) characterized by circumneutral waters, high conductivity and low nitrogen concentrations. The indicator value method (IndVal), based on the relative abundance and relative frequency of the most abundant taxa was calculated based on the groups observed in the CCA, identifying the characteristic taxa for each of the three groups. PMID:29118646

Low-temperature methyl bromide fumigation of emerald ash borer (Coleoptera: Buprestidae) in ash logs.

PubMed

Barak, Alan V; Elder, Peggy; Fraser, Ivich

2011-02-01

Ash (Fraxinus spp.) logs, infested with fully developed, cold-acclimated larval and prepupal emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), were fumigated with methyl bromide (MeBr) at 4.4 and 10.0 degrees C for 24 h. Concentrations X time dosages of MeBr obtained were 1579 and 1273 g-h/m3 (24-h exposure) at 4.4 and 10.0 degrees C after applied doses of 112 and 96 g/m3, respectively. MeBr concentrations were simultaneously measured with a ContainIR infrared monitor and Fumiscope thermal conductivity meter calibrated for MeBr to measure the effect of CO2 on Fumiscope concentration readings compared with the infrared (IR) instrument. The presence of CO2 caused false high MeBr readings. With the thermal conductivity meter, CO2 measured 11.36 g/m3 MeBr per 1% CO2 in clean air, whereas the gas-specific infrared ContainIR instrument measured 9.55% CO2 as 4.2 g/m3 MeBr (0.44 g/m3 per 1% CO2). The IR instrument was 0.4% as sensitive to CO2 as the thermal conductivity meter. After aeration, fumigated and control logs were held for 8 wk to capture emerging beetles. No A. planipennis adults emerged from any of the fumigated logs, whereas 262 emerged from control logs (139 and 123/m2 at 4.4 and 10.0 degrees C, respectively). An effective fumigation dose and minimum periodic MeBr concentrations are proposed. The use of a CO2 scrubber in conjunction with nonspecific thermal conductivity instruments is necessary to more accurately measure MeBr concentrations.

Localisation of atrial natriuretic peptide immunoreactivity in the ventricular myocardium and conduction system of the human fetal and adult heart.

PubMed Central

Wharton, J; Anderson, R H; Springall, D; Power, R F; Rose, M; Smith, A; Espejo, R; Khaghani, A; Wallwork, J; Yacoub, M H

1988-01-01

Atrial natriuretic peptide immunoreactivity was found in ventricular and atrial tissues with specific antisera raised to the amino and carboxy terminal regions of the precursor molecule. In 13 developing human hearts (7-24 weeks' gestation) the immunoreactivity was concentrated in the atrial myocardium and ventricular conduction system but it was also detected in the early fetal ventricular myocardium. Immunoreactivity in five normal adults was largely confined to the atrial myocardium although it was also found in the ventricular conduction tissues of hearts removed from 10 patients who were undergoing cardiac transplantation. The ventricular conduction system is an extra-atrial site for the synthesis of atrial natriuretic peptide. In the failing heart this synthesis may be further supplemented by expression of the gene in the ventricular myocardium. It is possible that ventricular production of the peptide contributes to the raised circulating concentrations of atrial natriuretic peptide immunoreactivity found in severe congestive heart disease, particularly in patients with dilated cardiomyopathy. Images Fig 1 Fig 2 Fig 3 Fig 4 Fig 5 PMID:2973340

Ion Speciation and Transport Properties of LiTFSI in 1,3-Dioxolane Solutions: A Case Study for Li-S Battery Applications.

PubMed

Raccichini, Rinaldo; Dibden, James W; Brew, Ashley; Owen, John R; García-Aráez, Nuria

2018-01-11

Lithium-sulfur battery is considered to be one of the main candidates for "post-lithium-ion" battery generation because of its high theoretical specific capacity and inherently low cost. The role of electrolyte is particularly important in this system, and remarkable battery performances have been reported by tuning the amount of salt in the electrolyte. To further understand the reasons for such improvements, we chose the lithium bis(trifluoromethanesulfonyl)imide in 1,3-dioxolane electrolyte as a model salt-solvent system for a systematic study of conductivity and viscosity over a wide range of concentration from 10 -5 up to 5 m. The experimental results, discussed and interpreted with reference to the theory of electrolyte conductance, lead to the conclusion that triple ion formation is responsible for the highest molal conductivity values before reaching the maximum at 1.25 m. At higher concentrations, the molal conductivity drops quickly because of a rapid increase in viscosity and the salt-solvent system can be treated as a diluted form of molten salt.

Impedance spectroscopy of PZT ceramics--measuring diffusion coefficients, mixed conduction, and Pb loss.

PubMed

Donnelly, Niall J; Randall, Clive A

2012-09-01

Sintering of lead zirconate titanate (PZT) at high temperatures results in loss of Pb unless an ambient Pb activity is maintained. The tell-tale sign of Pb loss is an increased conductivity, usually manifested in unacceptably high values of tanδ. The conductivity is caused by oxygen vacancies and/or electron holes which are a byproduct of Pb evaporation. In the first part of this paper, it is shown how impedance spectroscopy can be used to separate ionic and electronic conductivity in a properly designed sample by selection of appropriate boundary conditions. Subsequently, impedance is used to probe defect concentrations in PZT during prolonged annealing at 700°C. It is found that oxygen vacancies are generated during annealing in air but the rate of generation actually decreases upon lowering the ambient pO(2). These results are explained by a model of Pb evaporation which, in this case, leads predominantly to oxygen vacancy generation. In principle, this effect could be used to generate a specific vacancy concentration in similar Pb-based oxides.

Characterisation of nano- and micron-sized airborne and collected subway particles, a multi-analytical approach.

PubMed

Midander, Klara; Elihn, Karine; Wallén, Anna; Belova, Lyuba; Karlsson, Anna-Karin Borg; Wallinder, Inger Odnevall

2012-06-15

Continuous daily measurements of airborne particles were conducted during specific periods at an underground platform within the subway system of the city center of Stockholm, Sweden. Main emphasis was placed on number concentration, particle size distribution, soot content (analyzed as elemental and black carbon) and surface area concentration. Conventional measurements of mass concentrations were conducted in parallel as well as analysis of particle morphology, bulk- and surface composition. In addition, the presence of volatile and semi volatile organic compounds within freshly collected particle fractions of PM(10) and PM(2.5) were investigated and grouped according to functional groups. Similar periodic measurements were conducted at street level for comparison. The investigation clearly demonstrates a large dominance in number concentration of airborne nano-sized particles compared to coarse particles in the subway. Out of a mean particle number concentration of 12000 particles/cm(3) (7500 to 20000 particles/cm(3)), only 190 particles/cm(3) were larger than 250 nm. Soot particles from diesel exhaust, and metal-containing particles, primarily iron, were observed in the subway aerosol. Unique measurements on freshly collected subway particle size fractions of PM(10) and PM(2.5) identified several volatile and semi-volatile organic compounds, the presence of carcinogenic aromatic compounds and traces of flame retardants. This interdisciplinary and multi-analytical investigation aims to provide an improved understanding of reported adverse health effects induced by subway aerosols. Copyright © 2012 Elsevier B.V. All rights reserved.

Structure, magnetization, and low-temperature impedance response of polycrystalline InSe intercalated with nickel

NASA Astrophysics Data System (ADS)

Stakhira, Y. M.; Tovstyuk, N. K.; Fomenko, V. L.; Grigorchak, I. I.; Borysyuk, A. K.; Seredyuk, B. A.

2012-01-01

A solid-phase mechanochemical technology of production of polycrystalline InSе intercalated with Ni up to 1.25 at. % has been developed. The x-ray and phase analyses of the produced NixInSe samples confirm their homogeneity and demonstrate a nonmonotonic Ni-content dependence of the lattice constant along the axis normal to the layers. Analysis of the low-temperature (77 K) impedance response within the frequency region 10-3-106 Hz shows a good correlation between the change in interlayer distance and in the band conductivity observed with increasing Ni concentration. However, the Ni concentration dependence of specific magnetization demonstrates an irregular increase at x ˜ 1 and does not coincide with the former. Such behavior is explained by the proposed theoretical model, which at the same time unveiled the mechanism behind the increasing contribution of free carrier concentration to conductivity - hybridization of electron orbitals of guest nickel and the lattice layers.

Water Resources Data for California, 1965; Part 2: Water Quality Records

USGS Publications Warehouse

1965-01-01

Water quality information is presented for chemical quality, fluvial sediment, and water temperatures. The chemical quality includes concentrations of individual dissolved constituents and certain properties or characteristics such as hardness, sodium-adsorption-ratio, specific conductance, and pH. Fluvial sediment information is given for suspended-sediment discharges and concentrations and for particle-size distribution of suspended sediment and bed material. Water temperature data represent once-daily observations except for stations where a continuous temperature recorder furnishes information from which daily minimums and maximums are obtained.

Water Resources Data for California, 1966; Part 2: Water Quality Records

USGS Publications Warehouse

1967-01-01

Water-quality information is presented for chemical quality, fluvial sediment, and water temperatures. The chemical quality includes concentrations of individual dissolved constituents and certain properties or characteristics such as hardness, sodium-adsorption ratio, specific conductance, and pH. Fluvial-sediment information is given for suspended-sediment discharges and concentrations and for particle-size distribution of suspended sediment and bed material. Water-temperature data represent once-daily observations except for stations where a continuous temperature recorder furnishes information from which daily minimums and maximums are obtained.

Differentiating high priority pathway-based toxicity from non ...

EPA Pesticide Factsheets

The ToxCast chemical screening approach enables the rapid assessment of large numbers of chemicals for biological effects, primarily at the molecular level. Adverse outcome pathways (AOPs) offer a means to link biomolecular effects with potential adverse outcomes at the level of the individual or population, thus enhancing the utility of the ToxCast effort for hazard assessment. Thus, efforts are underway to develop AOPs relevant to the pathway perturbations detected in ToxCast assays. However, activity (?‘hits’) determined for chemical-assay pairs may reflect target-specific activity relevant to a molecular initiating event of an AOP, or more generalized cell stress and cytotoxicity-mediated effects. Previous work identified a ?‘cytotoxic burst’ phenomenon wherein large numbers of assays begin to respond at or near concentrations that elicit cytotoxicity. The concentration range at which the “burst” occurs is definable, statistically. Consequently, in order to focus AOP development on the ToxCast assay targetswhich are most sensitive and relevant to pathway-specific effects, we conducted a meta-analysis to identify which assays were frequently responding at concentrations well below the cytotoxic burst. Assays were ranked by the fraction of chemical hits below the burst concentration range compared to the number of chemicals tested, resulting in a preliminary list of potentially important, target-specific assays. After eliminating cytotoxicity a

Environmental geochemistry at Red Mountain, an unmined volcanogenic massive sulphide deposit in the Bonnifield district, Alaska Range, east-central Alaska

USGS Publications Warehouse

Eppinger, R.G.; Briggs, P.H.; Dusel-Bacon, C.; Giles, S.A.; Gough, L.P.; Hammarstrom, J.M.; Hubbard, B.E.

2007-01-01

The unmined, pyrite-rich Red Mountain (Dry Creek) deposit displays a remarkable environmental footprint of natural acid generation, high metal and exceedingly high rate earth element (REE) concentrations in surface waters. The volcanogenic massive sulphide deposit exhibits well-constrained examples of acid-generating, metal-leaching, metal-precipitation and self-mitigation (via co-precipitation, dilution and neutralization) processes that occur in an undisturbed natural setting, a rare occurrence in North America. Oxidative dissolution of pyrite and associated secondary reactions under near-surface oxidizing conditions are the primary causes for the acid generation and metal leaching. The deposit is hosted in Devonian to Mississippian felsic metavolcanic rocks of the Mystic Creek Member of the Totatlanika Schist. Water samples with the lowest pH (many below 3.5), highest specific conductance (commonly >2500 ??S/cm) and highest major- and trace-element concentrations are from springs and streams within the quartz-sericite-pyrite alteration zone. Aluminum, Cd, Co, Cu, Fe, Mn, Ni, Pb, Y, Zn and, particularly, the REEs are found in high concentrations, ranging across four orders of magnitude. Waters collected upstream from the alteration zone have near-neutral pH, lower specific conductance (370 to 830 ??S/cm), lower metal concentrations and measurable alkalinities. Water samples collected downstream of the alteration zone have pH and metal concentrations intermediate between these two extremes. Stream sediments are anomalous in Zn, Pb, S, Fe, Cu, As, Co, Sb and Cd relative to local and regional background abundances. Red Mountain Creek and its tributaries do not, and probably never have, supported significant aquatic life. ?? 2007 AAG/ Geological Society of London.

Relation of precipitation quality to storm type, and deposition of dissolved chemical constituents from precipitation in Massachusetts, 1983-85

USGS Publications Warehouse

Gay, F.B.; Melching, C.S.

1995-01-01

Precipitation samples were collected for 83 storms at a rural inland site in Princeton, Mass., and 73 storms at a rural coastal site in Truro, Mass., to examine the quality of precipitation from storms and relate quality to three storm types (oceanic cyclone, continental cyclone, and cold front). At the inland site, Princeton, ranked-means of precipitation depth, storm duration, specific conductance, and concentrations and loads of hydrogen, sulfate, aluminum, bromide, and copper ions were affected by storm type. At the coastal site, Truro, ranked means of precipitation depth, storm duration, and concentrations and loads of calcium, chloride, magnesium, potassium, and sodium ions were affected by storm type. Precipitation chemistry at the coastal site was 85 percent oceanic in orgin, whereas precipitation 72 kilometers inland was 60 percent hydrogen, nitrate, and sulfate ions, reflecting fossil-fuel combustion. Concentrations and loads for specific conductance and 9 chemical constituents on an annual and seasonal basis were determined from National Atmospheric Deposition Program data for spring 1983 through winter 1985 at Quabbin (rural, inland), Waltham (suburban, inland) and Truro (rural, coastal), Massachusetts. Concentrations of magnesium, potassium, sodium, and chloride concentrations were highest at the coast and much lower inland, with very little difference between Waltham and Quabbin. Loads of ammonium, nitrate, sulfate, and hydrogen are highest at Quabbin and are about equal at Waltham and Truro. About twice as much nitrate and hydrogen and about 35 percent more sulfate is deposited at Quabbin than at Waltham or Truro; this pattern indicates that the interior of Massachusetts receives more acidic precipitation than do the eastern or the coastal areas of Massachusetts.

Water-quality and sediment-chemistry data of drain water and evaporation ponds from Tulare Lake Drainage District, Kings County, California March 1985 to March 1986

USGS Publications Warehouse

Fujii, Roger

1988-01-01

Trace element and major ion concentrations were measured in water samples collected monthly between March 1985 and March 1986 at the MD-1 pumping station at the Tulare Lake Drainage District evaporation ponds, Kings County, California. Samples were analyzed for selected pesticides several times during the year. Salinity, as measured by specific conductance, ranged from 11,500 to 37,600 microsiemens/centimeter; total recoverable boron ranged from 4,000 to 16,000 micrg/L; and total recoverable molybdenum ranged from 630 to 2,600 microg/L. Median concentrations of total arsenic and total selenium were 97 and 2 microg/L. Atrazine, prometone, propazine, and simazine were the only pesticides detected in water samples collected at the MD-1 pumping station. Major ions, trace elements, and selected pesticides also were analyzed in water and bottom-sediment samples from five of the southern evaporation ponds at Tulare Lake Drainage District. Water enters the ponds from the MD-1 pumping station at pond 1 and flows through the system terminating at pond 10. The water samples increased in specific conductance (21,700 to 90,200 microsiemens/centimeter) and concentrations of total arsenic (110 to 420 microg/L), total recoverable boron (12,000 to 80,000 microg/L) and total recoverable molybdenum (1,200 to 5,500 microg/L) going from pond 1 to pond 10, respectively. Pesticides were not detected in water from any of the ponds sampled. Median concentrations of total arsenic and total selenium in the bottom sediments were 4.0 and 0.9 microg/g, respectively. The only pesticides detected in bottom sediment samples from the evaporation ponds were DDD and DDE, with maximum concentration of 0.8 microg/kilogram. (Author 's abstract)

A systematic review of vitamin D status in southern European countries.

PubMed

Manios, Yannis; Moschonis, George; Lambrinou, Christina-Paulina; Tsoutsoulopoulou, Konstantina; Binou, Panagiota; Karachaliou, Alexandra; Breidenassel, Christina; Gonzalez-Gross, Marcela; Kiely, Mairead; Cashman, Kevin D

2017-10-31

Despite an acknowledged dearth of data on serum 25-hydroxyvitamin D (25(OH)D) concentrations from Southern European countries, inter-country comparison is hampered by inconsistent data reporting. The purpose of the current study was to conduct a systematic literature review of available data on serum 25(OH)D concentrations and estimate vitamin D status in Southern European and Eastern Mediterranean countries, both at a population level and within key population subgroups, stratified by age, sex, season and country. A systematic review of the literature was conducted to identify and retrieve scientific articles reporting data on serum 25(OH)D concentration and/or vitamin D status following standard procedures. Data were extracted from 107 studies, stratified by sex and age group, representing 630,093 individuals. More than one-third of the studies reported mean 25(OH)D concentrations below 50 nmol/L and ~ 10% reported mean serum 25(OH)D concentrations below 25 nmol/L. Overall, females, neonates/ infants and adolescents had the higher prevalence of poor vitamin D status. As expected, there was considerable variability between studies. Specifically, mean 25(OH)D ranged from 6.0 (in Italian centenarians) to 158 nmol/L (in elderly Turkish men); the prevalence of serum 25(OH)D < 50 nmol/L ranged from 6.8 to 97.9% (in Italian neonates). Contrary to expectations, there was a high prevalence of low vitamin D status in the Southern Europe and the Eastern Mediterranean regions, despite abundant sunshine. These data further emphasize the need for strategies, such as fortification of foods with vitamin D and/or vitamin D supplementation, which will be tailored to the needs of specific population groups with higher risk of insufficiency or deficiency, to efficiently tackle the pandemic of hypovitaminosis D in Europe.

Surface-water-quality assessment of the Upper Illinois River basin in Illinois, Indiana, and Wisconsin; cross-sectional and depth variation of water-quality constituents and properties in the Upper Illinois River basin, 1987-88

USGS Publications Warehouse

Marron, Donna C.; Blanchard, Stephen F.

1995-01-01

Data on water velocity, temperature, specific con- ductance, pH, dissolved oxygen concentration, chlorophyll concentration, suspended sediment con- centration, fecal-coliform counts, and the percen- tage of suspended sediment finer than 62 micrometers ranged up to 21 percent; and cross-section coefficients of variation of the concentrations of suspended sediment, fecal coliform, and chlorophyll ranged from 7 to 115 percent. Midchannel measure- ments of temperature, specific conductance, and pH were within 5 percent of mean cross-sectional values of these properties at the eight sampling sites, most of which appear well mixed because of the effect of dams and reservoirs. Measurements of the concentration of dissolved oxygen at various cross- section locations and at variable sampling depths are required to obtain a representative value of this constituent at these sites. The large varia- bility of concentrations of chlorophyll and suspended sediment, and fecal-coliform counts at the eight sampling sites indicates that composite rather than midchannel or mean values of these constituents are likely to be most representative of the channel cross section.

Water-quality characteristics and trend analyses for the Tongue, Powder, Cheyenne, and Belle Fourche River drainage basins, Wyoming and Montana, for selected periods, water years 1991 through 2010

USGS Publications Warehouse

Clark, Melanie L.

2012-01-01

The Powder River structural basin in northeastern Wyoming and southeastern Montana is an area of ongoing coalbed natural gas (CBNG) development. Waters produced during CBNG development are managed with a variety of techniques, including surface impoundments and discharges into stream drainages. The interaction of CBNG-produced waters with the atmosphere and the semiarid soils of the Powder River structural basin can affect water chemistry in several ways. Specific conductance and sodium adsorption ratios (SAR) of CBNG-produced waters that are discharged to streams have been of particular concern because they have the potential to affect the use of the water for irrigation. Water-quality monitoring has been conducted since 2001 at main-stem and tributary sites in the Tongue, Powder, Cheyenne, and Belle Fourche River drainage basins in response to concerns about CBNG effects. A study was conducted to summarize characteristics of stream-water quality for water years 2001–10 (October 1, 2000, to September 30, 2010) and examine trends in specific conductance, SAR, and primary constituents that contribute to specific conductance and SAR for changes through time (water years 1991–2010) that may have occurred as a result of CBNG development. Specific conductance and SAR are the focus characteristics of this report. Dissolved calcium, magnesium, and sodium, which are primary contributors to specific conductance and SAR, as well as dissolved alkalinity, chloride, and sulfate, which are other primary contributors to specific conductance, also are described. Stream-water quality in the Tongue, Powder, Cheyenne, and Belle Fourche River drainage basins was variable during water years 2001–10, in part because of variations in streamflow. In general, annual runoff was less than average during water years 2001–06 and near or above average during water years 2007–10. Stream water of the Tongue River had the smallest specific conductance values, sodium adsorption ratios, and major ion concentrations of the main-stem streams. Sites in the Tongue River drainage basin typically had the smallest range of specific conductance and SAR values. The water chemistry of sites in the Powder River drainage basin generally was the most variable as a result of diverse characteristics of that basin. Plains tributaries in the Powder River drainage basin had the largest range of specific conductance and SAR values, in part due to the many tributaries that receive CBNG-produced waters. Trends were analyzed using the seasonal Kendall test with flow-adjusted concentrations to determine changes to water quality through time at sites in the Tongue, Powder, Cheyenne, and Belle Fourche River drainage basins. Trends were evaluated for water years 2001–10 for 17 sites, which generally were on the main-stem streams and primary tributaries. Trends were evaluated for water years 2005–10 for 26 sites to increase the spatial coverage of sites. Trends were evaluated for water years 1991–2010 for eight sites to include water-quality data collected prior to widespread CBNG development and expand the temporal context of trends. Consistent patterns were not observed in trend results for water years 2001–10 for flow-adjusted specific conductance and SAR values in the Tongue, Powder, and Belle Fourche River drainage basins. Significant (p-values less than 0.05) upward trends in flow-adjusted specific conductance values were determined for 3 sites, a downward trend was determined for 1 site, and no significant (p-value greater than 0.05) trends were determined for 13 sites. One of the sites with a significant upward trend was the Tongue River at the Wyoming-Montana State line. No trend in flow-adjusted specific conductance values was determined for the Powder River at Moorhead, Mont. Significant upward trends in flow-adjusted SAR values were determined for 2 sites and no significant trends were determined for 15 sites. No trends in flow-adjusted SAR values were determined for the Tongue River at the Wyoming-Montana State line or for the Powder River at Moorhead, Mont. One of the sites with a significant upward trend in flow-adjusted SAR values was the Powder River at Arvada, Wyo. For water years 2005–10, significant upward trends in flow-adjusted specific conductance values were determined no significant trends were determined for 13 sites. A significant upward trend was determined for flow-adjusted specific conductance values for the Tongue River at the Wyoming-Montana State line. No trend in flow-adjusted specific conductance values was determined for the Powder River at Moorhead, Mont. Significant upward trends in flow-adjusted SAR values were determined for 4 sites, downward trends were determined for 5 sites, and no significant trend was determined for 17 sites. No trends in flow-adjusted SAR values were determined for the Tongue River at the Wyoming-Montana State line or for the Powder River at Moorhead, Mont. Results of the seasonal Kendall test applied to flow-adjusted specific conductance values for water years 1991–2010 indicated no significant trend for eight sites in the Tongue, Powder, and Belle Fourche River drainage basins. No significant trend in flow-adjusted specific conductance was determined for the Tongue River at the Wyoming-Montana State line or the Powder River at Moorhead, Mont. Results of the seasonal Kendall test applied to flow-adjusted SAR values for water years 1991–2010 indicated an upward trend for one site and no significant trend for four sites in the Powder and Belle Fourche River drainage basins. The significant upward trend in flow-adjusted SAR values was determined for the Powder River at Arvada, Wyo., for water years 1991–2010. Results indicate that CBNG development in the Powder River structural basin may have contributed to some trends, such as the upward trend in flow-adjusted SAR for the Powder River at Arvada, Wyo., for water years 1991–2010. An upward trend in flow-adjusted alkalinity concentrations for water years 2001–10 also was determined for the Powder River at Arvada, Wyo. Trend results are consistent with changes that can occur from the addition of sodium and bicarbonate associated with CBNG-produced waters to the Powder River. Upward trends in constituents at other sites, including the Belle Fourche River, may be the result of declining CBNG development, indicating that CBNG-produced waters may have had a dilution effect on some streams. The factors affecting other trends could not be determined because multiple factors could have been affecting the stream-water quality or because trends were observed at sites upstream from CBNG development that may have affected water-quality trends at sites downstream.

Sewage plume in a sand and gravel aquifer, Cape Cod, Massachusetts

USGS Publications Warehouse

LeBlanc, D.R.

1982-01-01

Secondarily treated domestic sewage has been disposed of to a sand and gravel aquifer by infiltration through sand beds at Otis Air Force Base, Massachusetts, since 1936. The disposal has formed a plume of contaminated ground water that is more than 11 ,000 feet long, is 2,500 to 3,500 feet wide and 75 feet thick, and is overlain by 20 to 50 feet of uncontaminated ground water derived from precipitation. The distributions of specific conductance, temperature, boron chloride, sodium, phosphorus, nitrogen, ammonia, nitrate, dissolved oxygen, and detergents are used to delineate the plume. The center of the plume contains up to 2.6 milligrams per liter detergents as MBAS (methylene blue active substances), 0.4 milligram per liter boron, 20 milligrams per liter ammonia-nitrogen, and specific conductance as high as 405 micromhos per centimeter. Corresponding levels in uncontaminated ground water are less than 0.1 milligram per liter detergents, less than 0.1 ammonia-nitrogen, less than 0.05 milligram per liter boron, and less than 80 micromhos per centimeter specific conductance. Chloride, sodium, and boron concentrations seem to be affected only by hydrodynamic dispersion. Phosphorus movement is greatly retarded by sorption. Detergent concentrations exceed 0.5 milligram per liter from 3 ,000 to 10,000 feet from the sand beds and reflect the use of nonbiodegradable detergents from 1946 through 1964. The center of the plume as far as 5,000 feet from the sand beds contains nitrogen as ammonia, no nitrate, and no dissolved oxygen. Ammonia is oxidized to nitrate gradually with distance from the center of the plume. (USGS)

Electrical conduction hysteresis in carbon black-filled butyl rubber compounds

NASA Astrophysics Data System (ADS)

Alzamil, M. A.; Alfaramawi, K.; Abboudy, S.; Abulnasr, L.

2018-04-01

Temperature and concentration dependence of electrical resistance of butyl rubber filled with GPF carbon black was carried out. Current-voltage (I-V) characteristics at room-temperature were also investigated. The I-V characteristics show that the behavior is linear at small voltages up to approximately 0.15 V and currents up to 0.05 mA indicating that the conduction mechanism was probably due to electron tunneling from the end of conductive path to the other one under the action of the applied electric field. At higher voltages, a nonlinear behavior was noticed. The nonlinearity was attributed to the joule heating effects. Electrical resistance of the butyl/GPF composites was measured as a function of temperature during heating and cooling cycles from 300 K and upward to a specific temperature. When the specimens were heated up, the resistance was observed to increase continuously with the rise of temperature. However, when the samples were cooled down, the resistance was observed to decrease following a different path. The presence of conduction hysteresis behavior in the resistance-temperature curves during the heating and cooling cycles was then verified. The electrical conduction of the composite system is supposed to follow an activation conduction mechanism. Activation energy was calculated at different filler concentrations for both the heating and cooling processes.

Specific conductance and water temperature data for San Francisco Bay, California, for Water Year 2003

USGS Publications Warehouse

Buchanan, P.A.

2004-01-01

This article presents time-series graphs of specific-conductance and water-temperature data collected in San Francisco Bay during water year 2003 (October 1, 2002, through September 30, 2003). Specific-conductance and water-temperature data were recorded at 15-minute intervals at the following US Geological Survey (USGS) locations (Figure 1): • Suisun Bay at Benicia Bridge, near Benicia, CA. (BEN) (site # 11455780) • Carquinez Strait at Carquinez Bridge, near Crockett, CA. (CARQ) (site # 11455820) • Napa River at Mare Island Causeway, near Vallejo, CA. (NAP) (site # 11458370) • San Pablo Strait at Point San Pablo, CA. (PSP) (site # 11181360) • San Pablo Bay at Petaluma River Channel Marker 9, CA. (SPB) (site # 380519122262901) • San Francisco Bay at Presidio Military Reservation, CA. (PRES) (site # 11162690) • San Francisco Bay at San Mateo Bridge, near Foster City, CA. (SMB) (site # 11162765) Suspended-sediment-concentration data also were collected at most of these sites during water year 2003. Specific-conductance and water-temperature data from PSP, PRES, and SMB were recorded by the CA Department of Water Resources (DWR) before 1988, by the USGS National Research Program from 1988 to 1989, and by the USGS-DWR cooperative program since 1990. BEN, CARQ, NAP, and SPB were established in 1998 by USGS. The monitoring station at PRES was discontinued on November 12, 2002, due to shoaling at the site.

Streamflow and water-quality trends of the Rio Chama and Rio Grande, northern and central New Mexico, water years 1985 to 2002

USGS Publications Warehouse

Langman, Jeff B.; Nolan, Emma O.

2005-01-01

The City of Albuquerque plans to divert San Juan-Chama Project water from the Rio Grande for potable water use. This report examines streamflow and water-quality trends in the Rio Chama and the Rio Grande for water years 1985 to 2002 following the implementation of reservoir storage agreements in northern and central New Mexico. Streamflow/water-quality stations used for this study include the Rio Grande stations of Taos, Otowi, San Felipe, and Albuquerque and the Rio Chama station of Chamita. Water years 1985 to 2002 were a period of larger than average precipitation and streamflow compared to the stations. historical averages. Annual precipitation and streamflow trended downward during the study period because of a drought during 1999 to 2002. Streamflow in the Rio Chama and Rio Grande was divided into three distinct seasonal periods that corresponded to natural and anthropogenic influences: fall/winter baseflow (November through February), snowmelt runoff (March through June), and the irrigation/monsoon (July through October) seasons. A calcium bicarbonate water type was evident at all study area stations on the Rio Chama and Rio Grande. Specific conductance increased downstream, but alkalinity and pH did not substantially change in the downstream direction. Nearly all nitrogen and phosphorous concentrations were less than 1 milligram per liter for all stations. Median trace-element concentrations and maximum radionuclide concentrations did not exceed drinking-water standards. Anthropogenic compounds were infrequently detected in the Rio Chama and Rio Grande, and concentrations did not exceed drinking-water standards. Water quality in the Rio Chama and Rio Grande varied spatially and temporally during water years 1985 to 2002. Specific conductance increased downstream in the Rio Grande during the fall/winter baseflow and snowmelt runoff seasons but was similar at the Taos, Otowi, and San Felipe stations during the irrigation/monsoon season. This similarity was a result of the release of stored water from Abiquiu Reservoir and Cochiti Lake, which masked the natural influences that increased specific conductance in the downstream direction during the other seasons. During all seasons, pH decreased and major ion concentrations remained stable at the Albuquerque station compared with the San Felipe station, but no single influence could be identified that caused these conditions. Manganese and uranium concentrations at the Otowi and San Felipe stations were largest during the fall/winter baseflow and smallest during the snowmelt runoff, indicating that ground-water inflows likely influenced these concentrations. Water-quality temporal trends were evaluated for selected constituents during the study period and during the individual seasons. Downward trends in major ion concentrations were similar in magnitude at the Taos and Otowi stations, indicating that an upstream influence and (or) the downward trend in annual precipitation was the main reason(s) for these trends. The stations most affected by reservoirs, Chamita and San Felipe, were the only stations at which downward trends in major ions were apparent for flow-adjusted concentrations but not for seasonally correlated low-adjusted concentrations, which indicates fewer seasonal differences at these stations due to reservoir operations.

Regression models to estimate real-time concentrations of selected constituents in two tributaries to Lake Houston near Houston, Texas, 2005-07

USGS Publications Warehouse

Oden, Timothy D.; Asquith, William H.; Milburn, Matthew S.

2009-01-01

In December 2005, the U.S. Geological Survey in cooperation with the City of Houston, Texas, began collecting discrete water-quality samples for nutrients, total organic carbon, bacteria (total coliform and Escherichia coli), atrazine, and suspended sediment at two U.S. Geological Survey streamflow-gaging stations upstream from Lake Houston near Houston (08068500 Spring Creek near Spring, Texas, and 08070200 East Fork San Jacinto River near New Caney, Texas). The data from the discrete water-quality samples collected during 2005-07, in conjunction with monitored real-time data already being collected - physical properties (specific conductance, pH, water temperature, turbidity, and dissolved oxygen), streamflow, and rainfall - were used to develop regression models for predicting water-quality constituent concentrations for inflows to Lake Houston. Rainfall data were obtained from a rain gage monitored by Harris County Homeland Security and Emergency Management and colocated with the Spring Creek station. The leaps and bounds algorithm was used to find the best subsets of possible regression models (minimum residual sum of squares for a given number of variables). The potential explanatory or predictive variables included discharge (streamflow), specific conductance, pH, water temperature, turbidity, dissolved oxygen, rainfall, and time (to account for seasonal variations inherent in some water-quality data). The response variables at each site were nitrite plus nitrate nitrogen, total phosphorus, organic carbon, Escherichia coli, atrazine, and suspended sediment. The explanatory variables provide easily measured quantities as a means to estimate concentrations of the various constituents under investigation, with accompanying estimates of measurement uncertainty. Each regression equation can be used to estimate concentrations of a given constituent in real time. In conjunction with estimated concentrations, constituent loads were estimated by multiplying the estimated concentration by the corresponding streamflow and applying the appropriate conversion factor. By computing loads from estimated constituent concentrations, a continuous record of estimated loads can be available for comparison to total maximum daily loads. The regression equations presented in this report are site specific to the Spring Creek and East Fork San Jacinto River streamflow-gaging stations; however, the methods that were developed and documented could be applied to other tributaries to Lake Houston for estimating real-time water-quality data for streams entering Lake Houston.

Multijunction cells for concentrators: Technology prospects

NASA Technical Reports Server (NTRS)

Ferber, R. R. (Compiler); Costogue, E. N. (Compiler); Shimada, K. (Compiler)

1984-01-01

Development of high-efficiency multijunction solar cells for concentrator applications is a key step in achieving the goals of the U.S. Department of Energy National Photovoltaics Program. This report summarizes findings of an issue study conducted by the Jet Propulsion Laboratory Photovoltaic Analysis and Integration Center, with the assistance of the Solar Energy Research Institute and Sandia National laboratoies, which surveyed multijunction cell research for concentrators undertaken by federal agencies and by private industry. The team evaluated the potentials of research activities sponsored by DOE and by corporate funding to achieve projected high-efficiency goals and developed summary statements regarding industry expectations. Recommendations are made for the direction of future work to address specific unresolved aspects of multijunction cell technology.

Mineral profiling of ostrich (Struthio camelus) seminal plasma and its relationship with semen traits and collection day.

PubMed

Smith, A M J; Bonato, M; Dzama, K; Malecki, I A; Cloete, S W P

2018-06-01

Successful assisted reproduction techniques, with specific focus on in vitro semen storage for artificial insemination, are dependent on certain key elements which includes the biochemical profiling of semen. The objective of this study was to complete an ostrich seminal plasma (SP) evaluation by inductively coupled plasma mass spectrometry (ICP-MS) among seven males at different daily intervals (day 1, 3, 7, 11, 15, 19, 21, 23, 25, 26, 27, 28) for a period of 28 days during spring (August to September) for mineral profiling. The effect of collection day and male on sperm concentration, semen volume and seminal plasma volume, was explored as well as the relationships amongst these specific sperm traits and SP minerals. Variation amongst SP mineral concentrations, accounted for by the fixed effects of sperm concentration, semen volume, seminal plasma volume, collection day and male, ranged from 18% to 77%. Male had the largest effect on variation in SP minerals, namely: phosphorus (P), potassium (K), calcium (Ca), sodium (Na), boron (B), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), molybdenum (Mo), barium (Ba), arsenic (As) and selenium (Se). Sperm concentration instigated fluctuations of P, magnesium (Mg), B, zinc (Zn), Fe, aluminium (Al), Se, manganese (Mn) and lead (Pb). Semen volume had an effect on Na, K, B, Pb and Ba while seminal plasma volume only influenced variation in Na. There were fluctuations among collection days of specific micro minerals, Ni and Mo, with initial Ni concentrations being relatively greater and Mo at lesser concentrations. Semen volume, seminal plasma volume and sperm concentration varied amongst males. Sperm concentrations during the initial collection days, 1 and 3, were less than that for days 7 to 28. Significant variation of SP minerals and sperm characteristics among ejaculates and males suggest an association of these specific elements with sperm function and are, therefore, considered to be of potential importance to success of assisted reproduction technology for the ostrich. The relationship amongst sperm concentration and collection day confirms the need to conduct an initial period of collection to stabilise a greater sperm concentration to optimise sperm numbers for artificial insemination purposes. Copyright © 2018 Elsevier B.V. All rights reserved.

External quality-assurance results for the National Atmospheric Deposition Program/National Trends Network, 2002-03

USGS Publications Warehouse

Wetherbee, Gregory A.; Latysh, Natalie E.; Burke, Kevin P.

2005-01-01

Six external quality-assurance programs were operated by the U.S. Geological Survey (USGS) External Quality-Assurance (QA) Project for the National Atmospheric Deposition Program/National Trends Network (NADP/NTN) from 2002 through 2003. Each program measured specific components of the overall error inherent in NADP/NTN wet-deposition measurements. The intersite-comparison program assessed the variability and bias of pH and specific conductance determinations made by NADP/NTN site operators twice per year with respect to accuracy goals. The percentage of site operators that met the pH accuracy goals decreased from 92.0 percent in spring 2002 to 86.3 percent in spring 2003. In these same four intersite-comparison studies, the percentage of site operators that met the accuracy goals for specific conductance ranged from 94.4 to 97.5 percent. The blind-audit program and the sample-handling evaluation (SHE) program evaluated the effects of routine sample handling, processing, and shipping on the chemistry of weekly NADP/NTN samples. The blind-audit program data indicated that the variability introduced by sample handling might be environmentally significant to data users for sodium, potassium, chloride, and hydrogen ion concentrations during 2002. In 2003, the blind-audit program was modified and replaced by the SHE program. The SHE program was designed to control the effects of laboratory-analysis variability. The 2003 SHE data had less overall variability than the 2002 blind-audit data. The SHE data indicated that sample handling buffers the pH of the precipitation samples and, in turn, results in slightly lower conductivity. Otherwise, the SHE data provided error estimates that were not environmentally significant to data users. The field-audit program was designed to evaluate the effects of onsite exposure, sample handling, and shipping on the chemistry of NADP/NTN precipitation samples. Field-audit results indicated that exposure of NADP/NTN wet-deposition samples to onsite conditions tended to neutralize the acidity of the samples by less than 1.0 microequivalent per liter. Onsite exposure of the sampling bucket appeared to slightly increase the concentration of most of the analytes but not to an extent that was environmentally significant to NADP data users. An interlaboratory-comparison program was used to estimate the analytical variability and bias of the NADP Central Analytical Laboratory (CAL) during 2002-03. Bias was identified in the CAL data for calcium, magnesium, sodium, potassium, ammonium, chloride, nitrate, sulfate, hydrogen ion, and specific conductance, but the absolute value of the bias was less than analytical minimum detection limits for all constituents except magnesium, nitrate, sulfate, and specific conductance. Control charts showed that CAL results were within statistical control approximately 90 percent of the time. Data for the analysis of ultrapure deionized-water samples indicated that CAL did not have problems with laboratory contamination. During 2002-03, the overall variability of data from the NADP/NTN precipitation-monitoring system was estimated using data from three collocated monitoring sites. Measurement differences of constituent concentration and deposition for paired samples from the collocated samplers were evaluated to compute error terms. The medians of the absolute percentage errors (MAEs) for the paired samples generally were larger for cations (approximately 8 to 50 percent) than for anions (approximately 3 to 33 percent). MAEs were approximately 16 to 30 percent for hydrogen-ion concentration, less than 10 percent for specific conductance, less than 5 percent for sample volume, and less than 8 percent for precipitation depth. The variability attributed to each component of the sample-collection and analysis processes, as estimated by USGS quality-assurance programs, varied among analytes. Laboratory analysis variability accounted for approximately 2 percent of the

Method for concentration and separation of biological organisms by ultrafiltration and dielectrophoresis

DOEpatents

Simmons, Blake A.; Hill, Vincent R.; Fintschenko, Yolanda; Cummings, Eric B.

2012-09-04

Disclosed is a method for monitoring sources of public water supply for a variety of pathogens by using a combination of ultrafiltration techniques together dielectrophoretic separation techniques. Because water-borne pathogens, whether present due to "natural" contamination or intentional introduction, would likely be present in drinking water at low concentrations when samples are collected for monitoring or outbreak investigations, an approach is needed to quickly and efficiently concentrate and separate particles such as viruses, bacteria, and parasites in large volumes of water (e.g., 100 L or more) while simultaneously reducing the sample volume to levels sufficient for detecting low concentrations of microbes (e.g., <10 mL). The technique is also designed to screen the separated microbes based on specific conductivity and size.

Water-quality investigation, Salinas River, California

USGS Publications Warehouse

Irwin, G.A.

1976-01-01

Concentrations of dissolved solids in the Salinas River, California, are variable and range from 164 to 494 milligrams per liter near Bradley and from 170 to 1,090 milligrams per liter near Spreckels. Higher concentrations near Spreckels are caused mainly by sewage inflow about 150 feet (50 meters) upstream. Concentrations of nitrogen, phosphorus, total organic carbon, selected trace elements, and pesticides also generally increase downstream from Pozo to Spreckels and are related to sewage effluent; however, high concentrations occur elsewhere in the river. Specific conductance and water discharge regression results indicate that relations were all significant at the 1-percent probability level at Paso Robles, Bradley, and Spreckels with the explained variance ranging from 66 to 74 percent. Concentations of nitrogen, phosphorus, total organic carbon, and trace elements are only infrequently related to water discharge. (Woodard-USGS)

Threshold concentration in the nonlinear absorbance law.

PubMed

Tolbin, Alexander Yu; Pushkarev, Victor E; Tomilova, Larisa G; Zefirov, Nikolay S

2017-05-24

A new nonlinear relationship of the absorption coefficient with the concentration was proposed, allowing the calculation of the threshold concentration, which shows that there is a deviation from the Beer-Lambert law. The nonlinear model was successfully tested on a stable dimeric phthalocyanine ligand of J-type in solvents with different polarity. It was shown that deviation from the linearity is connected with a specific association of the macrocyclic molecules, which, in the case of non-polar solvents, leads to the formation of H-aggregates composed of J-type dimeric molecules. The aggregation number was estimated to be less than 1.5, which has allowed us to conduct a series of analytical experiments in a wide range of concentrations (1 × 10 -6 -5 × 10 -4 mol L -1 ).

Methods for estimating monthly mean concentrations of selected water-quality constituents for stream sites in the Red River of the North basin, North Dakota and Minnesota

USGS Publications Warehouse

Guenthner, R.S.

1991-01-01

Future development of the Garrison Diversion Unit may divert water from the Missouri River into the Sheyenne River and the Red River of the North for municipal and industrial use. The U.S. Bureau of Reclamation's Canals, Rivers, and Reservoirs Salinity Accounting Procedures model can be used to predict the effect various operating plans could have on water quality in the Sheyenne River and the Red River of the North. The model uses, as Input, monthly means of streamflow and selected water-quality constituents for a 54-year period at 28 nodes on the Sheyenne River and the Red River of the North. This report provides methods for estimating monthly mean concentrations of selected water-quality constituents that can be used for input to and calibration of the salinity model.Mater-quality data for 32 gaging stations can be used to define selected water-quality characteristics at the 28 model nodes. Materquality data were retrieved from the U.S. Geological Survey's National Mater Data Storage and Retrieval System data base and statistical summaries were prepared. The frequency of water-quality data collection at the gaging stations is inadequate to define monthly mean concentrations of the individual water-quality constituents for all months for the 54-year period; therefore, methods for estimating monthly mean concentrations were developed. Relations between selected water-quality constituents [dissolved solids, hardness (as CaCO3), sodium, sulfate, and chloride] and streamflow were developed as the primary method to estimate monthly mean concentrations. Relations between specific conductance and streamflow and relations between selected water-quality constituents [dissolved solids, hardness (as CaCO3), sodium, sulfate, and chloride] and specific conductance were developed so that a cascaded-regression relation could be developed as a second method of estimating monthly mean concentrations and, thus, utilize a large specific-conductance data base. Information about the quantity and the quality of ground water discharging to the Sheyenne River is needed for model input for reaches of the river where ground water accounts for a substantial part of streamflow during periods of low flow. Ground-water discharge was identified for two reaches of the Sheyenne River. Ground-water discharge to the Sheyenne River in the vicinity of Warwick, N.Dak., was about 14.8 cubic feet per second and the estimated dissolved-solids concentration was about 441 milligrams per liter during October 15 and 16, 1986. Ground-water discharge to the Sheyenne River in a reach between Lisbon and Kindred, N.Dak., ranged from an average of 25.3 cubic feet per second during September 13 to November 19, 1963, to about 45.0 cubic feet per second during October 21 and 22, 1986. Dissolved-solids concentration was estimated at about 442 milligrams per liter during October 21 and 22, 1986.

BASIC Programming In Water And Wastewater Analysis

NASA Technical Reports Server (NTRS)

Dreschel, Thomas

1988-01-01

Collection of computer programs assembled for use in water-analysis laboratories. First program calculates quality-control parameters used in routine water analysis. Second calculates line of best fit for standard concentrations and absorbances entered. Third calculates specific conductance from conductivity measurement and temperature at which measurement taken. Fourth calculates any one of four types of residue measured in water. Fifth, sixth, and seventh calculate results of titrations commonly performed on water samples. Eighth converts measurements, to actual dissolved-oxygen concentration using oxygen-saturation values for fresh and salt water. Ninth and tenth perform calculations of two other common titrimetric analyses. Eleventh calculates oil and grease residue from water sample. Last two use spectro-photometric measurements of absorbance at different wavelengths and residue measurements. Programs included in collection written for Hewlett-Packard 2647F in H-P BASIC.

The effects of feed-borne Fusarium mycotoxins and glucomannan in turkey poults based on specific and non-specific parameters.

PubMed

Devreese, Mathias; Girgis, George N; Tran, Si-Trung; De Baere, Siegrid; De Backer, Patrick; Croubels, Siska; Smith, Trevor K

2014-01-01

An experiment was conducted to investigate the effects of feeding grains naturally contaminated with Fusarium mycotoxins and a yeast derived glucomannan mycotoxin adsorbent (GMA) on selected specific and non-specific parameters in turkey poults. Two hundred and forty 1-day-old male turkey poults were fed the experimental diets for twelve weeks. Experimental diets were formulated with control grains, control grains+0.2% GMA, naturally-contaminated grains, or naturally-contaminated grains+0.2% GMA. Deoxynivalenol (DON) was the major contaminant of the contaminated grains and concentrations varied from 4.0 to 6.5 mg/kg in the contaminated diets. Non-specific parameters measured included: performance parameters, plasma biochemistry profiles, morphometry and CD8(+) T-lymphocyte counts in the duodenum. Plasma concentrations of DON and de-epoxydeoxynivalenol (DOM-1) were used as specific parameters. Performance parameters and plasma biochemistry were altered by the feeding of contaminated diets and GMA but this was not consistent throughout the trial. The feeding of contaminated diets reduced duodenal villus height and apparent villus surface area. This effect was prevented by GMA supplementation. The feeding of contaminated diets elevated total duodenal CD8(+) T-lymphocyte counts but this effect was not prevented by GMA. No significant differences were seen in plasma concentrations of DON and DOM-1 comparing birds fed contaminated and contaminated+GMA diets suggesting that GMA did not prevent DON absorption under these conditions. Copyright © 2013 Elsevier Ltd. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Torrey, M S

The report is a synoptic review of data collected over the past twenty years on the chemistry of Lake Michigan. Changes in water quality and sediment chemistry, attributable to cultural and natural influences, are considered in relation to interacting processes and factors controlling the distribution and concentration of chemical substances within the Lake. Temperature, light, and mixing processes are among the important natural influences that affect nutrient cycling, dispersal of pollutants, and fate of materials entering the Lake. Characterization of inshore-offshore and longitudinal differences in chemical concentrations and sediment chemistry for the main body of the Lake is supplemented bymore » discussion of specific areas such as Green Bay and Grand Traverse Bay. Residues, specific conductance, dissolved oxygen, major and trace nutrients, and contaminants are described in the following context: biological essentiality and/or toxicity, sources to the Lake, concentrations in the water column and sediments, chemical forms, seasonal variations and variation with depth. A summary of existing water quality standards, statutes, and criteria applicable to Lake Michigan is appended.« less

Hydrologic exchange and chemical weathering in a proglacial watershed near Kangerlussuaq, west Greenland

NASA Astrophysics Data System (ADS)

Deuerling, Kelly M.; Martin, Jonathan B.; Martin, Ellen E.; Scribner, Cecilia A.

2018-01-01

The exchange of proglacial river water with active layer pore water could alter water chemical compositions in glacial outwash plains and oceanic solute fluxes. To evaluate effects of this exchange, we sampled Watson River and adjacent pore water during the 2013 melt season at two sandurs in western Greenland; one in Sandflugtdalen and the other near the confluence with Søndre Strømfjord. We measured temperature, specific conductivity, and head gradients between the river and bank over a week-long period at Sandflugtdalen, as well as sediment hydraulic conductivity and chemical compositions of waters from both sites. Specific conductivity of pore water is four to ten times greater than river water as solutes are concentrated from weathering reactions, cryoconcentration, and evaporation. Pore water compositions are predominantly altered by carbonate dissolution and sulfide mineral oxidation. High concentrations of HCO3 and SO4 result from solute recycling and dissolution of secondary Ca-Mg carbonate/sulfate salts initially formed by near-surface evaporation in the summer and at depth by freeze-in of the active layer and cryoconcentration in the winter. High hydraulic conductivity (10-5 to 10-4 m/s) and diurnal fluctuations of river stage during our study caused exchange of river and pore water immediately adjacent to the river channel, with a net loss of river water to the bank. Pore water >6 m from the river continuously flowed away from the river. Approximately 1-8% of the river discharge through the Sandflugtdalen was lost to the river bank during our 6.75 day study based on calculations using Darcy's Law. Although not sampled, some of this water should discharge to the river during low river stage early and late in the melt season. Elevated pore water solute concentrations in sandurs and water exchange at diurnal and seasonal frequency should impact fluxes of solutes to the ocean, although understanding the magnitude of this effect will require long-term evaluation throughout the melt season.

Floodwater Chemistry in the Yolo Bypass during Winter and Spring 1998

USGS Publications Warehouse

Schemel, Laurence E.; Cox, Marisa H.

2007-01-01

A preliminary investigation of temporal and spatial variations in floodwater chemistry was conducted during winter and spring 1998 in the Yolo Bypass floodplain of the Sacramento River system. Samples were collected at locations along the eastern margin of the floodplain over the duration of the study and across the floodplain during major periods of inundation. Specific conductance and dissolved organic carbon concentrations along the eastern margin of the Yolo Bypass varied inversely with discharge. The Sacramento River was the greatest source of discharge to the floodplain during major periods of inundation. Increases in specific conductance and dissolved organic carbon were observed along the eastern margin during periods of lower discharge, when local streams accounted for a significant fraction of the total discharge through the Yolo Bypass. Apparent influences of local stream discharges also were observed in surface waters near the western margin of the floodplain during major periods of inundation. Although river and local stream sources of suspended particulate matter appeared important, in-floodplain processes were likely contributors to temporal and spatial variability in concentrations. Values for the C:N ratio of the particulate matter were lowest during periods of decreasing and low discharge through the floodplain, indicating production of phytoplankton in floodplain waters or supply to the floodplain by local stream sources. Phytoplankton discharged from the Yolo Bypass was detected by chlorophyll a monitors downstream in the Sacramento River during this study.

Regional patterns of total nitrogen concentrations in the National Rivers and Streams Assessment

USGS Publications Warehouse

Omernik, James M.; Paulsen, Steven G.; Griffith, Glenn E.; Weber, Marc H.

2016-01-01

Patterns of nitrogen (N) concentrations in streams sampled by the National Rivers and Streams Assessment (NRSA) were examined semiquantitatively to identify regional differences in stream N levels. The data were categorized and analyzed by watershed size classes to reveal patterns of the concentrations that are consistent with the spatial homogeneity in natural and anthropogenic characteristics associated with regional differences in N levels. Ecoregions and mapped information on human activities including agricultural practices were used to determine the resultant regions. Marked differences in N levels were found among the nine aggregations of ecoregions used to report the results of the NRSA. We identified distinct regional patterns of stream N concentrations within the reporting regions that are associated with the characteristics of specific Level III ecoregions, groups of Level III ecoregions, groups of Level IV ecoregions, certain geographic characteristics within ecoregions, and/or particular watershed size classes. We described each of these regions and illustrated their areal extent and median and range in N concentrations. Understanding the spatial variability of nutrient concentrations in flowing waters and the apparent contributions that human and nonhuman factors have on different sizes of streams and rivers is critical to the development of effective water quality assessment and management plans. This semi-quantitative analysis is also intended to identify areas within which more detailed quantitative work can be conducted to determine specific regional factors associated with variations in stream N concentrations.

A study of thermal conductivity in graphene diodes and transistors with intrinsic defects and subjected to metal impurities

NASA Astrophysics Data System (ADS)

Sadeghzadeh, Sadegh; Rezapour, Navid

2016-12-01

In this paper, the effect of the presence of cavities resulting from the fabrication process and the effect of common metal impurities added during the synthesis process on the thermal conductivity of single-layer graphene sheets, diodes and transistors have been investigated by using the Reverse Non Equilibrium Molecular Dynamics (RNEMD) method. The obtained results show that thermal conductivity generally diminishes by increasing the concentration of nanoparticles and increases when porosities and impurities are at the edges of sheets. Regarding a better thermal management in graphene with the addition of nanoparticles, and considering its existing porosity, a lower thermal conductivity is achieved by adding more nanoparticles. By increasing the diameter of pores from 0.5 nm to 4.4 nm in a specific single-layer graphene sheet, thermal conductivity diminishes from 67 W/mk to 1.43 W/mk; while it diminishes from 45 to 1.0 W/mk for the same structure containing both the defects and nanoparticles over the defects. In evaluating the influences of cavities and metallic nanoparticles on thermal conductivity, it was observed that changing the share of cavities or nanoparticles has a significant effect on the thermal conductivity of graphene diodes and transistors. The rectification efficiency of diodes diminished from about 100% for the defect-free diode to about 19% for the diode containing 2 nm cavities and then increased to 75% for the diode with 5 nm cavities. While, with the increase in the concentration of iron nanoparticles, the rectification efficiency increased from about 100% for the diode with no iron particles to about 255% for the diode containing 13 wt % of iron particles. Final results demonstrate that the metallic nanoparticles and also defects with specific diameters can be effectively exploited to increase or decrease the efficiency of nanodiodes and nanotransistors. This leads to engineered design of nanodiodes and nanotransistors for various applications.

Comment on `Electrical conductance of a sandstone partially saturated with varying concentrations of NaCl solutions' by R. Umezawa, N. Nishiyama, M. Katsura and S. Nakashima

NASA Astrophysics Data System (ADS)

Revil, André; Soueid Ahmed, Abdellahi

2017-11-01

Umezawa et al. investigated the dependence of the electrical conductivity of rocks with respect to the saturation of the water phase. Four issues can be underlined in their work: (1) The conductivity model they used mixes bulk and surface tortuosities in the same linear equation (i.e., between the conductivity and the conductivity of the pore water). This conflicts with the fact that the conductivity is a concave down increasing function of the pore water conductivity and bulk tortuosity is defined only at high salinity while surface tortuosity is defined only at very low salinity. (2) The specific surface conductance obtained by Umezawa et al. is too low and conflicts with independent evaluations obtained with double layer models for aluminosilicates and silicates. (3) The expression given for the resistivity index conflicts with the inclusion of a surface conductivity term in the conductivity equation.

Conductivity Evolution of Fracture Proppant in Partial Monolayers and Multilayers

NASA Astrophysics Data System (ADS)

Fan, M.; Han, Y.; McClure, J. E.; Chen, C.

2017-12-01

Proppant is a granular material, typically sand, coated sand, or man-made ceramic materials, which is widely used in hydraulic fracturing to keep the induced fractures open. Optimization of proppant placement in a hydraulic fracture, as well as its role on the fracture's conductivity, is vital for effective and economical production of petroleum hydrocarbons. In this research, a numerical modeling approach, combining Discrete Element Method (DEM) with lattice Boltzmann (LB) method, was adopted to advance the understanding of fracture conductivity as function of proppant concentration under various effective stresses. DEM was used to simulate effective stress increase and the resultant proppant particle compaction and rearrangement during the process of reservoir depletion due to hydrocarbon extraction. DEM-simulated pore structure was extracted and imported into the LB simulator as boundary conditions to calculate the time-dependent permeability of the proppant pack. We first validated the DEM-LB coupling workflow; the simulated proppant pack permeabilities as functions of effective stress were in good agreement with laboratory measurements. Next, several proppant packs were generated with various proppant concentrations, ranging from partial-monolayer to multilayer structures. Proppant concentration is defined as proppant mass per unit fracture face area. Fracture conductivity as function of proppant concentration was measured in LB simulations. It was found that a partial-monolayer proppant pack with large-diameter particles was optimal in maintaining sufficient conductivity while lowering production costs. Three proppant packs with the same average diameter but different diameter distributions were generated. Specifically, we used the coefficient of variation (COV) of diameter, defined as the ratio of standard deviation of diameter to mean diameter, to characterize the heterogeneity in particle size. We obtained proppant pack porosity, permeability, and fracture width reduction as functions of effective stress. Under the same effective stress, a proppant pack with a smaller diameter COV had higher porosity and permeability and smaller fracture width reduction, which are all favorable for maintaining the fracture conductivity during the process of hydrocarbon extraction.

Effect of synthesized ZnO nanoparticles on thermal conductivity and mechanical properties of natural rubber

NASA Astrophysics Data System (ADS)

Suntako, R.

2018-01-01

Zinc oxide (ZnO) is widely used in rubber industry as a cure activator for rubber vulcanization. In this work, comparison of cure characteristic, mechanical properties, thermal conductivity and volume swell testing in oil no.1 and oil no.3 between natural rubber (NR) filled synthesized ZnO nanoparticles (sZnO) by precipitation method and NR filled conventional ZnO (cZnO). The particle size of sZnO is 41.50 nm and specific area of 27.92 m2/g, the particle size of cZnO is 312.92 nm and specific surface area of 1.35 m2/g. It has been found that NR filled sZnO not only improves rubber mechanical properties, volume swell testing but also improves thermal conductivity and better than NR filled cZnO. Thermal conductivity of NR filled sZnO increases by 10.34%, 12.90% and 20.00%, respectively when compared with NR filled cZnO in same loading content (various concentrations of ZnO at 5, 8 and 10 parts per hundred parts of rubber). This is due to small particle size and large specific surface area of sZnO which lead to an increase in crosslinking in rubber chain and enhance heat transfer performance.

Continuous water-quality monitoring and regression analysis to estimate constituent concentrations and loads in the Sheyenne River, North Dakota, 1980-2006

USGS Publications Warehouse

Ryberg, Karen R.

2007-01-01

This report presents the results of a study by the U.S. Geological Survey, done in cooperation with the North Dakota State Water Commission, to estimate water-quality constituent concentrations at seven sites on the Sheyenne River, N. Dak. Regression analysis of water-quality data collected in 1980-2006 was used to estimate concentrations for hardness, dissolved solids, calcium, magnesium, sodium, and sulfate. The explanatory variables examined for the regression relations were continuously monitored streamflow, specific conductance, and water temperature. For the conditions observed in 1980-2006, streamflow was a significant explanatory variable for some constituents. Specific conductance was a significant explanatory variable for all of the constituents, and water temperature was not a statistically significant explanatory variable for any of the constituents in this study. The regression relations were evaluated using common measures of variability, including R2, the proportion of variability in the estimated constituent concentration explained by the explanatory variables and regression equation. R2 values ranged from 0.784 for calcium to 0.997 for dissolved solids. The regression relations also were evaluated by calculating the median relative percentage difference (RPD) between measured constituent concentration and the constituent concentration estimated by the regression equations. Median RPDs ranged from 1.7 for dissolved solids to 11.5 for sulfate. The regression relations also may be used to estimate daily constituent loads. The relations should be monitored for change over time, especially at sites 2 and 3 which have a short period of record. In addition, caution should be used when the Sheyenne River is affected by ice or when upstream sites are affected by isolated storm runoff. Almost all of the outliers and highly influential samples removed from the analysis were made during periods when the Sheyenne River might be affected by ice.

Hydrogeology and ground-water quality of northern Bucks County, Pennsylvania

USGS Publications Warehouse

Sloto, Ronald A.; Schreffler, Curtis L.

1994-01-01

Water from wells in the crystalline rocks has the lowest median pH (5.8), the lowest median specific conductance (139 microsiemens per centimeter), the lowest median alkalinity [16 mg/L (milligrams per liter) as CaCOg], and the highest dissolved oxygen concentration (9.0 mg/L) of the hydrogeologic units. Water from wells in carbonate rocks has the highest median pH (7.8) and the highest median alkalinity (195 mg/L as CaCO3) of the hydrogeologic units. Water from wells in the Lockatong Formation has the highest median specific conductance (428 microsiemens per centimeter) and the lowest dissolved oxygen concentration (0.8 mg/L) of the hydrogeologic units. Water from wells in crystalline rocks contains the lowest concentrations of total dissolved solids (TDS) of the hydrogeologic units. Water from the Lockatong Formation contains the highest concentration of TDS of the hydrogeologic units. Water from only 1 of 83 wells sampled exceeded the U.S. Environmental Protection Agency (USEPA) secondary maximum contaminant level (SMCL) for TDS; the well is in the Lockatong Formation. Five of 86 samples (6 percent) and 6 of 75 samples (8 percent) exceed the USEPA SMCL for iron and manganese, respectively. Nitrate is the most prevalent nitrogen species in ground water. The median nitrate concentration for all hydrogeologic units is 2.3 mg/L. Of 71 water samples from wells, no concentrations of nitrate exceed the USEPA maximum contaminant level. The median dissolved radon-222 activity was highest for water samples from wells in crystalline rock [3,600 pCi/L (picocuries per liter)] and lowest for water samples from wells in the Lockatong Formation (340 pCi/L) and diabase (350 pCi/L). Water samples for analysis for volatile organic compounds (VOC's) were collected from 34 wells in areas where the potential existed for the presence of VOC's in ground water. VOC's were detected in 23 percent of the 34 wells sampled. The most commonly detected compound was trichloroethylene (13 percent of sampled wells).

Hydrology and water quality of Elkhead Creek and Elkhead Reservoir near Craig, Colorado, July 1995-September 2001

USGS Publications Warehouse

Kuhn, Gerhard; Stevens, Michael R.; Elliott, John G.

2003-01-01

The U.S. Geological Survey, in cooperation with the Colorado River Water Conservation District, collected and analyzed baseline streamflow and water-quality information for Elkhead Creek and water-quality and trophic-state information for Elkhead Reservoir from July 1995 through September 2001. In the study area, Elkhead Creek is a meandering, alluvial stream dominated by snowmelt in mountainous headwaters that produces most of the annual discharge volume and discharge peaks during late spring and early summer. During most of water year 1996 (a typical year), daily mean discharge at station 09246400 (downstream from the reservoir) was similar to daily mean discharge at station 09246200 (upstream from the reservoir). Flow-duration curves for stations 09246200 and 09246400 were nearly identical, except for discharges less than about 10 cubic feet per second. Specific conductance generally had an inverse relation to discharge in Elkhead Creek. During late fall and winter when discharge was small and derived mostly from ground water, specific conductance was high, whereas during spring and early summer, when discharge was large and derived mostly from snowmelt, specific conductance was low. Water temperatures in Elkhead Creek were smallest during winter, about 0.0 degrees Celsius (oC), and largest during summer, about 20?25oC. Concentrations of major ions, nutrients, trace elements, organic carbon, and suspended sediment in Elkhead Creek indicated no substantial within-year variability and no substantial differences in variability from one year to the next. A seasonal pattern in the concentration data was evident for most constituents. The seasonal concentration pattern for most of the dissolved constituents followed the seasonal pattern of specific conductance, whereas some nutrients, some trace elements, and suspended sediment followed the seasonal pattern of discharge. Statistical differences between station 09246200 (upstream from the reservoir) and station 09246400 (downstream from the reservoir) were indicated for specific conductance, dissolved calcium, magnesium, sodium, and sulfate, acid-neutralizing capacity, and dissolved solids. Trend analysis indicated upward temporal trends for pH, dissolved ammonia plus organic nitrogen, total nitrogen, and total phosphorus at station 09246200; upward temporal trends for dissolved and total ammonia plus organic nitrogen, total nitrogen, and total phosphorus were indicated at station 09246400. No downward trends were indicated for any constituents. Annual loads for dissolved constituents during water years 1996?2001 were consistently larger at station 09246400 than at station 09246200, except for silica and sulfate. Mean monthly loads for dissolved constituents followed the seasonal pattern of discharge, indicating that most of the annual loads were transported during March?June. Annual dissolved nutrient loads at stations 09246400 and 09246200 were not substantially different, except for total phosphorus and total nitrogen loads, which were smaller at the downstream station than at the upstream station, most likely due to biological uptake and settling in the reservoir. Mean annual suspended-sediment load during water years 1996?2001 was about 87-percent smaller at the downstream station than at the upstream station. Temperature in Elkhead Reservoir varied seasonally, from about 0oC during winter when ice develops on the reservoir to about 20oC during summer. Specific conductance varied from minimums of 138 to 169 microsiemens per centimeter at 25oC (?S/cm) during snowmelt inflow to maximums of 424 to 610 ?S/cm during early spring low flow (April). Median pH in the reservoir ranged from 7.2 to 8.0 at all sites near the surface. Median dissolved oxygen ranged from 7.1 to 7.2 milligrams per liter (mg/L) in near-surface samples and from 4.8 to 5.6 mg/L in near-bottom samples. During reservoir stratification, specific conductance generally was largest in the e

Phosphorus in a ground-water contaminant plume discharging to Ashumet Pond, Cape Cod, Massachusetts, 1999

USGS Publications Warehouse

McCobb, Timothy D.; LeBlanc, Denis R.; Walter, Donald A.; Hess, Kathryn M.; Kent, Douglas B.; Smith, Richard L.

2003-01-01

The discharge of a plume of sewagecontaminated ground water emanating from the Massachusetts Military Reservation to Ashumet Pond on Cape Cod, Massachusetts, has caused concern about excessive loading of nutrients, particularly phosphorus, to the pond. The U.S. Air Force is considering remedial actions to mitigate potentially adverse effects on the ecological characteristics of the pond from continued phosphorus loading. Concentrations as great as 3 milligrams per liter of dissolved phosphorus (as P) are in ground water near the pond's shoreline; concentrations greater than 5 milligrams per liter of phosphorus are in ground water farther upgradient. Temporary drive-point wells were used to collect water samples from 2 feet below the pond bottom to delineate concentration distributions in the pore waters of the pond-bottom sediments. Measurements in the field of specific conductance and colorimetrically determined orthophosphate concentrations provided real-time data to guide the sampling. The contaminant plume discharges to the Fishermans Cove area of Ashumet Pond as evidenced by elevated levels of specific conductance and boron, which are chemically conservative indicators of the sewage-contaminated ground water. Concentrations of nonconservative species, such as dissolved phosphorus, manganese, nitrate, and ammonium, also were elevated above background levels in ground water discharging to the pond, but in spatially complex distributions that reflect their distributions in ground water upgradient of the pond. Phosphorus concentrations exceeded background levels (greater than 0.10 milligram per liter) in the pond-bottom pore water along 875 feet of shoreline. Greatest concentrations (greater than 2 milligrams per liter) occurred within 30 feet of the shore in an area about 225 feet long. Calculations of phosphorus flux in the aquifer upgradient of Ashumet Pond, as determined from water-flux estimates from a steady-state ground-water-flow model and phosphorus concentrations (in 1999) from multilevel samplers about 75 feet upgradient of the pond, indicate that dissolved phosphorus moves towards the pond and discharges to it with the inflowing ground water at a rate as high as about 316 kilograms per year.

Aquifer characteristics, water availability, and water quality of the Quaternary aquifer, Osage County, northeastern Oklahoma, 2001-2002

USGS Publications Warehouse

Mashburn, Shana L.; Cope, Caleb C.; Abbott, Marvin M.

2003-01-01

Additional sources of water are needed on the Osage Reservation for future growth and development. The Quaternary aquifer along the Arkansas River in the Osage Reservation may represent a substantial water resource, but limited amounts of hydrogeologic data were available for the aquifer. The study area is about 116 square miles of the Quaternary aquifer in the Arkansas River valley and the nearby upland areas along the Osage Reservation. The study area included the Arkansas River reach downstream from Kaw Lake near Ponca City, Oklahoma to upstream from Keystone Lake near Cleveland, Oklahoma. Electrical conductivity logs were produced for 103 test holes. Water levels were determined for 49 test holes, and 105 water samples were collected for water-quality field analyses at 46 test holes. Water-quality data included field measurements of specific conductance, pH, water temperature, dissolved oxygen, and nitrate (nitrite plus nitrate as nitrogen). Sediment cores were extracted from 20 of the 103 test holes. The Quaternary aquifer consists of alluvial and terrace deposits of sand, silt, clay, and gravel. The measured thickness of the alluvium ranged from 13.7 to 49.8 feet. The measured thickness of the terrace sediments ranged from 7 to 93.8 feet. The saturated thickness of all sediments ranged from 0 to 38.2 feet with a median of 24.8 feet. The weighted-mean grain size for cores from the alluvium ranged from 3.69 to 0.64 f, (0.08- 0.64 millimeter), and ranged from 4.02 to 2.01 f (0.06-0.25 millimeter) for the cores from terrace deposits. The mean of the weighted-mean grain sizes for cores from the alluvium was 1.67 f (0.31 millimeter), and the terrace deposits was 2.73 f (0.15 millimeter). The hydraulic conductivity calculated from grain size of the alluvium ranged from 2.9 to 6,000 feet per day and of the terrace deposits ranged from 2.9 to 430 feet per day. The calculated transmissivity of the alluvium ranged from 2,000 to 26,000 feet squared per day with a median of 5,100 feet squared per day. Water in storage in the alluvium was estimated to be approximately 200,000 acre-feet. The amount of water annually recharging the aquifer was estimated to be approximately 4,800 acre-feet. Specific conductance for all water samples ranged from 161 to 6,650 microsiemens per centimeter. Median specific conductance for the alluvium was 683 microsiemens per centimeter and for the terrace deposits was 263 microsiemens per centimeter. Dissolved-solids concentrations, estimated from specific conductance, for water samples from the aquifer ranged from 88 to 3,658 milligrams per liter. Estimated median dissolved- solids concentration for the alluvium was 376 milligrams per liter and for the terrace deposits was 145 milligrams per liter. More than half of the samples from the Quaternary aquifer were estimated to contain less than 500 milligrams per liter dissolved solids. Field-screened nitrate concentrations for the sampling in December 2001-August 2002 ranged from 0 to 15 milligrams per liter. The field-screened nitrate concentrations for the second sampling in September 2002 were less than corresponding laboratory reported values.

Regression model development and computational procedures to support estimation of real-time concentrations and loads of selected constituents in two tributaries to Lake Houston near Houston, Texas, 2005-9

USGS Publications Warehouse

Lee, Michael T.; Asquith, William H.; Oden, Timothy D.

2012-01-01

In December 2005, the U.S. Geological Survey (USGS), in cooperation with the City of Houston, Texas, began collecting discrete water-quality samples for nutrients, total organic carbon, bacteria (Escherichia coli and total coliform), atrazine, and suspended sediment at two USGS streamflow-gaging stations that represent watersheds contributing to Lake Houston (08068500 Spring Creek near Spring, Tex., and 08070200 East Fork San Jacinto River near New Caney, Tex.). Data from the discrete water-quality samples collected during 2005–9, in conjunction with continuously monitored real-time data that included streamflow and other physical water-quality properties (specific conductance, pH, water temperature, turbidity, and dissolved oxygen), were used to develop regression models for the estimation of concentrations of water-quality constituents of substantial source watersheds to Lake Houston. The potential explanatory variables included discharge (streamflow), specific conductance, pH, water temperature, turbidity, dissolved oxygen, and time (to account for seasonal variations inherent in some water-quality data). The response variables (the selected constituents) at each site were nitrite plus nitrate nitrogen, total phosphorus, total organic carbon, E. coli, atrazine, and suspended sediment. The explanatory variables provide easily measured quantities to serve as potential surrogate variables to estimate concentrations of the selected constituents through statistical regression. Statistical regression also facilitates accompanying estimates of uncertainty in the form of prediction intervals. Each regression model potentially can be used to estimate concentrations of a given constituent in real time. Among other regression diagnostics, the diagnostics used as indicators of general model reliability and reported herein include the adjusted R-squared, the residual standard error, residual plots, and p-values. Adjusted R-squared values for the Spring Creek models ranged from .582–.922 (dimensionless). The residual standard errors ranged from .073–.447 (base-10 logarithm). Adjusted R-squared values for the East Fork San Jacinto River models ranged from .253–.853 (dimensionless). The residual standard errors ranged from .076–.388 (base-10 logarithm). In conjunction with estimated concentrations, constituent loads can be estimated by multiplying the estimated concentration by the corresponding streamflow and by applying the appropriate conversion factor. The regression models presented in this report are site specific, that is, they are specific to the Spring Creek and East Fork San Jacinto River streamflow-gaging stations; however, the general methods that were developed and documented could be applied to most perennial streams for the purpose of estimating real-time water quality data.

Water quality signals from rural land use and exurbanization in a mountain landscape: What’s clear and what’s comfounded

Treesearch

C. Rhett Jackson; Robert A. Bahn; Jackson R. Webster

2017-01-01

In mountainous landscapes with high climatic and geomorphic variability, how do rural land uses and exurbanization alter hydrology and water quality? We evaluated effects of rural land use and exurbanization on streamflows, suspended sediment concentrations and loads, specific conductance, and summer water temperatures in 12 streams and rivers within the Upper...

Measuring Intracellular Enzyme Concentrations: Assessing the Effect of Oxidative Stress on the Amount of Glyoxalase I

ERIC Educational Resources Information Center

Miranda, Hugo Vicente; Ferreira, Antonio E. N.; Quintas, Alexandre; Cordeiro, Carlos; Freire, Ana Ponces

2008-01-01

Enzymology is one of the fundamental areas of biochemistry and involves the study of the structure, kinetics, and regulation of enzyme activity. Research in this area is often conducted with purified enzymes and extrapolated to "in vivo" conditions. The specificity constant, k[subscript S], is the ratio between k[subscript cat] (the catalytic…

Can a sample of Landsat sensor scenes reliably estimate the global extent of tropical deforestation?

Treesearch

R. L. Czaplewski

2003-01-01

Tucker and Townshend (2000) conclude that wall-to-wall coverage is needed to avoid gross errors in estimations of deforestation rates' because tropical deforestation is concentrated along roads and rivers. They specifically question the reliability of the 10% sample of Landsat sensor scenes used in the global remote sensing survey conducted by the Food and...

Chemical and biological quality of selected lakes in Ohio, 1978 and 1979

USGS Publications Warehouse

Angelo, C.G.; Youger, John D.

1985-01-01

Twenty-eight Ohio lakes were sampled by the U.S. Geological Survey and the Ohio Environmental Protection Agency for water-quality characteristics during the spring and summer of 1978 and 1979. This report is the third in a series covering a lake-sampling program that began in 1975. Data include water-column profiles of temperature, dissolved oxygen, pH, and specific conductance. Chemical, physical, and biological properties were measured at specific points in the water column, and selected physical and chemical properties also were measured in the principal inflows. The lakes were predominatly hard (120 180 milligrams per liter) to very hard water, although several soft-water lakes were found in southeastern Ohio. Calcium, bicarbonate, and sulfate were the principal dissolved constituents. Specific conductance ranged from 103 micromhos per centimeter (at 25 degrees Celsius) at Tycoon Lake, 1978, to 2,550 micromhos per centimeter at West Fork Mill Creek Lake, 1978. Thirteen lakes had trace-element concentrations that were above the limits for exceptional warm-water habitat recammended by the Ohio Environmental Protection Agency. Seasonal thermal gradients developed in most lakes deeper than 17 feet. Oxygen concentrations were zero or near zero during the summer sampling of the bottom water of all lakes having definite thermal gradients. Most anaerobic zones contained hydrogen sulfide and high concentrations of ammonia. All lakes were evaluated and classified by Carlson's trophic state index. Most of the lakes were classified as eutrophic. Blue-green algae (CyanophytaJ) dominated the summer algal communities. Fecal colifrom counts were within Ohio standards, although high (more than 1,000 colonies per 100 milliliters) fecal colifrom and fecal streptococcus counts were observed in West Fork Mill Creek Lake after significant runoff.

Properties and chemical constituents in ground water from the middle Claiborne Aquifer, Gulf Coast regional aquifer systems, south-central United States

USGS Publications Warehouse

Pettijohn, Robert A.; Busby, John F.; Cervantes, Michael A.

1993-01-01

The U.S. Geological Survey used four programs in 1990 to provide external data quality assurance for the National Atmospheric Deposition Program/National Trends Network (NADP/NTN). Results of the intersite- comparison program indicate that 80 and 74 percent of the site operators met the NADP/NTN goals for pH determination and 98 and 95 percent of the site operators met the NADP/NTN goals for specific- conductance determination during the two studies in 1990. The effects of routine sample handling, processing, and shipping determined in the blind-audit program indicated significant positive bias for calcium, magnesium, sodium, potassium, chloride, nitrate, and sulfate. Significant negative bias was determined for hydrogen ion and specific conductance. A Kruskal-Wallis test indicated that there were no significant (a=0.01) differences in analytical results from the three laboratories participating in the interlaboratory-comparison program. Results from the collocated-sampler study indicate the median relative error for potassium and ammonium concentration and deposition exceeded 15 percent at most sites while the median relative error for sulfate and nitrate at all sites was less than 6 percent for concentration and was less than 15 percent for deposition.

A new mechanism for selective adsorption of rubber on carbon black surface caused by nano-confinement in SBR/NBR solution

NASA Astrophysics Data System (ADS)

Kawazoe, Masayuki

A novel mechanism of selective adsorption of rubber molecules onto carbon black surface in a binary immiscible rubber blend solution has been proposed in this dissertation. The phenomenon leads to uneven distribution of carbon black to the specific polymer in the blend and the obtained electrically conductive composite showed drastic reduction of percolation threshold concentration (PTC). The mechanism and the feature of conductive network formation have much potential concerning both fundamental understanding and industrial application to improve conductive polymer composites. In chapter I, carbon black filled conductive polymer composites are briefly reviewed. Then, in chapter II, a mechanism of rubber molecular confinement into carbon black aggregate structure is introduced to explain the selective adsorption of a specific rubber onto carbon black surface in an immiscible rubber solution blend (styrene butadiene rubber (SBR) and acrylonitrile butadiene rubber (NBR) with toluene or chloroform). Next, in chapters III and IV, polymers with various radius of gyration (Rg) and carbon blacks with various aggregate structure are examined to verify the selective adsorption mechanism. Finally, in chapter V, the novel mechanism was applied to create unique meso-/micro-unit conductive network in carbon black dispersed SBR/NBR composites.

Constitutional rho-kinase regulates atrioventricular nodal conduction and ventricular repolarization of the canine heart.

PubMed

Sugiyama, Atsushi; Takahara, Akira; Yatomi, Yutaka; Satoh, Yoshioki; Nakamura, Yuji; Hashimoto, Keitaro

2003-06-01

Given the limited information, physiological roles of Rho-kinase in the cardiac conduction system and ventricular repolarization process were assessed in comparison with those in the coronary vascular tone. A specific Rho-kinase inhibitor Y-27632 was administered to the nutrient coronary artery of the canine isolated, blood-perfused atrioventricular node preparation under the monitoring of the ventricular monophasic action potentials. Administration of Y-27632 moderately suppressed the atrioventricular nodal conduction, slightly but significantly accelerated the repolarization process, and potently increased the coronary blood flow, whereas it hardly affected the intraventricular conduction. The estimated concentrations of Y-27632 causing the currently observed effects were enough to inhibit Rho-kinase. These results suggest that constitutional Rho-kinase functions to moderately facilitate the atrioventricular nodal conduction, slightly delay ventricular repolarization process, and significantly increase the coronary vascular tone.

Increasing atmospheric [CO2] from glacial through future levels affects drought tolerance via impacts on leaves, xylem and their integrated function

PubMed Central

Medeiros, Juliana S.; Ward, Joy K.

2013-01-01

Summary Changes in atmospheric carbon dioxide concentration ([CO2]) affect plant carbon/water trade-offs, with implications for drought tolerance. Leaf-level studies often indicate that drought tolerance may increase with rising [CO2], but integrated leaf and xylem responses are not well understood in this respect. In addition, the influence of low [CO2] of the last glacial period on drought tolerance and xylem properties is not well understood.We investigated the interactive effects of a broad range of [CO2] and plant water potentials on leaf function, xylem structure and function and the integration of leaf and xylem function in Phaseolus vulgaris.Elevated [CO2] decreased vessel implosion strength, reduced conduit specific hydraulic conductance, and compromised leaf specific xylem hydraulic conductance under moderate drought. By contrast, at glacial [CO2], transpiration was maintained under moderate drought via greater conduit specific and leaf specific hydraulic conductance in association with increased vessel implosion strength.Our study involving the integration of leaf and xylem responses suggests that increasing [CO2] does not improve drought tolerance. We show that under glacial conditions changes in leaf and xylem properties could increase drought tolerance, while under future conditions greater productivity may only occur when higher water use can be accommodated. PMID:23668237

Evaluation of three percent Aqueous Film Forming Foam (AFFF) concentrates as fire fighting agents

NASA Astrophysics Data System (ADS)

Jablonski, E. J.

1981-04-01

A large-scale fire test program involving 20,000-square foot JP-4 fuel fires was conducted to evaluate the fire suppression effectiveness and compatibility of 3 percent Aqueous Film Forming Foam (AFFF) agents in Air Force fire fighting vehicles. Three commercially available 3 percent AFFF concentrates were tested in accordance with military specification MIL-F-24385B. Test results are summarized in Appendix A. As a result of these tests, an updated Revision C to this MIL SPEC has been accomplished with new requirements for both 3 percent and 6 percent AFFF extinguishing agents.

Streamflow, water quality, and aquatic macroinvertebrates of selected streams in Fairfax County, Virginia, 2007-12

USGS Publications Warehouse

Jastram, John D.

2014-01-01

Efforts to mitigate the effects of urbanization on streams rely on best management practices (BMPs) that are implemented with the intent of reducing and retaining stormwater runoff. A cooperative monitoring effort between the U.S. Geological Survey and Fairfax County, Virginia, was initiated in 2007 to assess the condition of county streams and document watershed-scale responses to the implementation of BMPs. Assessment of the data collected during the first 5 years of this monitoring program focused on characterizing the hydrologic and ecological condition of 14 monitored streams. Hydrologic, chemical, and macroinvertebrate community conditions in the streams monitored were found to be consistent, overall, with conditions commonly observed in urban streams. Hydrologically, the monitored streams were found to be flashy, with flashiness positively related to road cover in the watershed. Typical pH values of streams throughout the network centered around neutrality (pH = 7) with strong daily fluctuations apparent in the continuous data. Patterns in specific conductance were largely representative of anthropogenic disturbances—watersheds having the greatest percentage of open space and estate residential land-use had the lowest typical specific conductance values, and specific conductance variability was less than what is observed in watersheds that are more intensively developed. In watersheds having greater road coverage, and more development in general, increases in specific conductance over several orders of magnitude were observed during winter months as a result of the application of de-icing salts on impervious surfaces. Dissolved oxygen conditions were typically within the range required to support healthy biological communities, although occasional departures during summer months at some sites fell below the impairment threshold for streams in Virginia. Nitrogen (N) and phosphorus (P), concentration patterns were largely consistent across the network, with few exceptions. Nitrogen concentrations in monthly samples were generally low and dominated by nitrate. Exceptions to the generally low N concentrations occurred at Captain Hickory Run, which had a median total N concentration of approximately 4.9 milligrams per liter (mg/L), compared to the network-wide median of approximately 1.7 mg/L, and at Popes Head Creek Tributary, where total N concentrations spiked to 6–8 mg/L during low-flow periods in August or September of each year. Phosphorus concentrations in monthly samples were generally low and dominated by the dissolved fraction. Two monitoring stations in the network, Flatlick Branch and Frog Branch, are notable for having median total P concentrations that were, on average, approximately three times greater than the median total P concentration of 0.02 mg/L observed at the other 12 stations in the network. Suspended-sediment and nutrient loads and yields were similar to those of urbanized watersheds in other studies, although the yields from these urbanized basins were greater than, or within, the upper quartile of yields observed throughout the Chesapeake Bay watershed. Annual suspended-sediment loads ranged from 289–10,275 tons, with a median of 1,311 tons, and corresponding yields ranged from 107–2,827 tons per square mile (ton/mi2), with a median of 277 ton/mi2. Annual total N loads ranged from 8,014–36,413 pounds, with a median of 21,314 pounds, and corresponding yields ranged from 3,361–8,360 pounds per square mile (lb/mi2), with a median of 6,200 lb/mi2. Annual total P loads ranged from 380–6,558 pounds, with a median of 1,874 pounds, and corresponding yields ranged from 140–1,562 lb/mi2, with a median of 543 lb/mi2. Benthic macroinvertebrate community metrics indicated that streams throughout Fairfax County are generally of poor health. One station, Castle Creek, was an exception with results indicating relatively high quality aquatic health. Six additional monitoring stations were added to the network in 2012 to improve spatial coverage throughout Fairfax County. Monitoring activities are expected to continue at all 20 stations for the foreseeable future as BMP implementation is conducted.

Water-chemistry and chloride fluctuations in the Upper Floridan Aquifer in the Port Royal Sound area, South Carolina, 1917-93

USGS Publications Warehouse

Landmeyer, J.E.; Belval, D.L.

1996-01-01

Withdrawal of water from the Upper Floridan aquifer south of Port Royal Sound in Beaufort and Jasper Counties, South Carolina, has lowered water levels and reversed the hydraulic gradient beneath Hilton Head Island, South Carolina. Ground water that had previously discharged at the Sound is now being deflected southwest, toward withdrawals located near the city of Savannah, Georgia, and the island of Hilton Head. The reversal of this hydraulic gradient and the decline of water levels have caused saltwater in the Upper Floridan aquifer north of Port Royal Sound to begin moving southwest, toward water-supply wells for the town of Hilton Head and toward industries pumping ground water near Savannah. Analytical results from ground-water samples collected from wells in the Upper Floridan aquifer beneath and adjacent to Port Royal Sound show two plumes in the aquifer with chloride concentrations above the drinking- water standard. One plume of high chloride concentration extends slightly south of the theoretical predevelopment location of the steady- state freshwater-saltwater interface as indicated by numerical modeling. The other plume is present beneath the town of Port Royal, where the upper confining unit above the Upper Floridan aquifer is thin or absent. In these areas, the decline in water levels caused by ground-water withdrawals may have made it possible for water from tidal creeks to enter the Upper Floridan aquifer. Many wells completed in the upper permeable zone of the Upper Floridan aquifer show a distinct specific- conductance profile. One non-producing, monitoring well on Hilton Head Island (BFT-1810) was selected to depict a worst-case scenario to examine the short- and long-term water-chemistry and chloride fluctuations in the aquifer. Specific conductance was monitored at depths of 170, 190, and 200 feet below the top of the well casing. The specific conductance measured in 1987 ranged from approximately 450 microsiemens per centimeter near the top of the Upper Floridan aquifer to 1,500 microsiemens per centimeter near the lower, less permeable zone. Short-term fluctuations in conductance were measured at each probe and were found to be related to water-level fluctuations in the well caused by tidal cycles. The conductance varied regularly up to 100 microsiemens per centimeter, with an increasing time lag between high and low tides and low and high specific conductance for progressively shallower depths. Well BFT-1810 was monitored for specific conductance and water levels from October 1987 through September 1993. Specific conductance at the 170-foot probe showed little long-term change, while the 190- and the 200-foot probes showed long-term increases to approximately 4,000 and 10,000 microsiemens per centimeter, respectively. This well is located closest to one of the two plumes of saltwater delineated in the Upper Floridan aquifer, and the long-term chloride increases are a result of the movement of saltwater in the Upper Floridan aquifer toward Hilton Head Island under the influence of regional ground-water withdrawals.

Chemical quality of water in abandoned zinc mines in northeastern Oklahoma and southeastern Kansas

USGS Publications Warehouse

Playton, Stephen J.; Davis, Robert Ellis; McClaflin, Roger G.

1978-01-01

Onsite measurements of pH, specific conductance, and water temperature show that water temperatures in seven mine shafts in northeastern Oklahoma and southeastern Kansas is stratified. With increasing sampling depth, specific conductance and water temperature tend to increase, and pH tends to decrease. Concentrations of dissolved solids and chemical constituents in mine-shaft water, such as total, and dissolved metals and dissolved sulfate also increase with depth. The apparently unstable condition created by cooler, denser water overlying warmer, less-dense water is offset by the greater density of the lower water strata due to higher dissolved solids content.Correlation analysis showed that several chemical constituents and properties of mine-shaft water, including dissolved solids, total hardness, and dissolved sulfate, calcium, magnesium, and lithium, are linearly related to specific conductance. None of the constituents or properties of mine-shaft water tested had a significant linear relationship to pH. However, when values of dissolved aluminum, zinc, and nickel were transformed to natural or Napierian logarithms, significant linear correlation to pH resulted. During the course of the study - September 1975 to June 1977 - the water level in a well penetrating the mine workings rose at an average rate of 1.2 feet per month.  Usually, the rate of water-level rise was greater than average after periods of relatively high rainfall, and lower than average during periods of relatively low rainfall.Water in the mine shafts is unsuited for most uses without treatment.  The inability of current domestic water treatment practices to remove high concentrations of toxic metals, such as cadmium and lead, precludes use of the water for a public supply.

Silver concentrations and selected hydrologic data in the Upper Colorado River basin, 1991-92

USGS Publications Warehouse

Johncox, D.A.

1993-01-01

The U.S. Geological Survey, in cooperation with the Colorado River Water Conservation District and the Northern Colorado Water Conservancy District, collected water and sediment samples in May and September 1991 and 1992 from nine stream-sampling sites and three lake-sampling sites within the Upper Colorado River Basin upstream from Kremmling, Colorado. Data were collected to determine the present (1992) conditions of the Upper Colorado River Basin regarding silver concentrations in the water and sediment. Lake-water and stream-water samples were analyzed for concentrations of total recoverable silver, dissolved silver, and suspended solids. Lake- and stream-bottom material was analyzed for concentrations of total recoverable silver. Additional data collected were streamflow, specific conductance, pH, and water temperature. Transparency (Secchi-disk measurements) also was measured in the lakes.

Analysis of water-quality trends at two discharge stations; one within Big Cypress National Preserve and one near Biscayne Bay; southern Florida, 1966-94

USGS Publications Warehouse

Lietz, A.C.

2000-01-01

An analysis of water-quality trends was made at two U.S. Geological Survey daily discharge stations in southern Florida. The ESTREND computer program was the principal tool used for the determination of water-quality trends at the Miami Canal station west of Biscayne Bay in Miami and the Tamiami Canal station along U.S. Highway 41 in the Big Cypress National Preserve in Collier County. Variability in water quality caused by both seasonality and streamflow was compensated for by applying the nonparametric Seasonal Kendall trend test to unadjusted concentrations or flow-adjusted concentrations (residuals) determined from linear regression analysis. Concentrations of selected major inorganic constituents and physical characteristics; pH and dissolved oxygen; suspended sediment; nitrogen, phosphorus, and carbon species; trace metals; and bacteriological and biological characteristics were determined at the Miami and Tamiami Canal stations. Median and maximum concentrations of selected constituents were compared to the Florida Class III freshwater standards for recreation, propagation, and maintenance of a healthy, well-balanced population of fish and wildlife. The median concentrations of the water-quality constituents and characteristics generally were higher at the Miami Canal station than at the Tamiami Canal station. The maximum value for specific conductance at the Miami Canal station exceeded the State standard. The median and maximum concentrations for ammonia at the Miami and Tamiami Canal stations exceeded the State standard, whereas median dissolved-oxygen concentrations at both stations were below the State standard. Trend results were indicative of either improvement or deterioration in water quality with time. Improvement in water quality at the Miami Canal station was reflected by downward trends in suspended sediment (1987-94), turbidity, (1970-78), total ammonia (1971-94), total phosphorus (1987-94), barium (1978-94), iron (1969-94), and fecal coliform (1976-94). Deterioration in water quality at the same station was indicated by upward trends in specific conductance (1966-94), dissolved solids (1966-94, 1976-94, and 1987-94), chloride (1966-94), potassium (1966-94), magnesium (1966-94), sodium (1966-94), sulfate (1966-94), silica (1966-94), suspended sediment (1974-94), total organic carbon (1970-81), and fecal streptococcus (1987-94). The downward trend in pH (1966-94) was indicative of deterioration in water quality at the Miami Canal station. Improvement in water quality at the Tamiami Canal station was reflected by downward trends in fluoride (1967-93), total ammonia (1970-92), total nitrite plus nitrate (1975-85), and barium (1978-93). Deterioration in water quality at the same station was statistically significant by upward trends in specific conductance (1967-93), dissolved solids (1967-93), chloride (1967-93), sodium (1967-93), potassium (1967-93), magnesium (1967-93), strontium (1967-93), and suspended sediment (1976-93). The downward trend in dissolved oxygen (1970-93) was indicative of deterioration in water quality.

Acid-precipitation studies in Colorado and Wyoming: Interim report of surveys of Montane amphibians and water chemistry. Interim report, 1986-1988

DOE Office of Scientific and Technical Information (OSTI.GOV)

Corn, P.S.; Stolzenburg, W.; Bury, R.B.

1989-06-01

Surveys for amphibians were conducted in the Rocky Mountains of northern Colorado and southern Wyoming from 1986 to 1988. The northern leopard frog (Rana pipiens) was present at only 12% of historically known localities, and the boreal toad (Bufo boreas) was present at 17% of known localities. Chorus frogs (Pseudacris triseriata) suffered a catastrophic decline in population size in one population monitored since 1961, but regionally, this species was observed in 64% of known localities. Tiger salamanders (Ambystoma tigrinum) and wood frogs (Rana sylvatica) were present at 45% and 69% of known localities respectively. Acid neutralizing capacity, pH, specific conductivity,more » and cation concentrations in water at amphibian localities were negatively correlated with elevation. Survival of wood frog embryos declined when exposed to aluminum concentrations.« less

Electrochemical probing of high-level radioactive waste tanks containing washed sludge and precipitates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bickford, D.F.; Congdon, J.W.; Oblath, S.B.

1987-01-01

At the U.S. Department of Energy's Savannah River Plant, corrosion of carbon steel storage tanks containing alkaline, high-level radioactive waste is controlled by specification of limits on waste composition and temperature. Processes for the preparation of waste for final disposal will result in waste with low corrosion inhibitor concentrations and, in some cases, high aromatic organic concentrations, neither of which are characteristic of previous operations. Laboratory tests, conducted to determine minimum corrosion inhibitor levels indicated pitting of carbon steel near the waterline for proposed storage conditions. In situ electrochemical measurements of full-scale radioactive process demonstrations have been conducted to assessmore » the validity of laboratory tests. Probes included pH, Eh (potential relative to a standard hydrogen electrode), tank potential, and alloy coupons. In situ results are compared to those of the laboratory tests, with particular regard given to simulated solution composition.« less

Geohydrology and ground-water geochemistry at a sub-arctic landfill, Fairbanks, Alaska

USGS Publications Warehouse

Downey, J.S.

1990-01-01

The Fairbanks-North Star Borough, Alaska, landfill is located on silt, sand, and gravel deposits of the Tanana River flood plain, about 3 miles south of the city of Fairbanks water supply wells. The landfill has been in operation for about 25 years in this sub-arctic region of discontinuous permafrost. The cold climate limits biological activity within the landfill with corresponding low gas and leachate production. Chloride concentrations, specific conductance, water temperature, and earth conductivity measurements indicate a small plume of leachate flowing to the northwest from the landfill. The leachate remains near the water table as it flows northwestward toward a drainage ditch. Results of computer modeling of this local hydrologic system indicate that some of the leachate may be discharging to the ditch. Chemical data show that higher-than-background concentrations of several ions are present in the plume. However, the concentrations appear to be reduced to background levels within a short distance along the path of groundwater flow from the landfill, and thus the leachate is not expected to affect the water supply wells. (USGS)

Technology development of a biowaste resistojet, volume 1

NASA Technical Reports Server (NTRS)

Phillips, D. G.

1972-01-01

The materials research effort conducted in support of a NASA-sponsored biowaste resistojet development program is summarized. The resistojet concept under development is the concentric tube design wherein the final pass of the gases through the thruster is through the resistance heated center tube. To produce high specific impulses, this center tube must operate at very high temperatures and it is this element that is most critical in the design. Because of the corrosive nature of the biowaste gases at high temperature, and because of the limited data available for many potential materials, the subject materials study was conducted.

Compensation Effect in the Electrical Conduction Process in Some Nucleic Acid Base Complexes with Proflavine Dye

NASA Astrophysics Data System (ADS)

Sarkar, D.; Misra, T. N.

1988-11-01

Compensation behaviour has been found in electrical conduction process in proflavine complexes with nucleic acid bases, guanine, adenine, uracil and thymine. At low dye concentrations these semiconducting complexes follow a three constant compensation equation σ(T){=}σ0'\\exp (E/2kT0)\\exp (-E/2kT), σ0' and T0 being constants for a specific base. The other notations have their usual meaning. Consistent values of these constants have been obtained by different experimental methods of evaluation. These results suggest that compensation effect has a physical origin.

A New Approach to Look at the Electrical Conductivity of Streamflow: Decomposing a Bulk Signal to Recover Individual Solute Concentrations at High-Frequency

NASA Astrophysics Data System (ADS)

Benettin, P.; Van Breukelen, B. M.

2017-12-01

The ability to evaluate stream hydrochemistry is often constrained by the capacity to sample streamwater at an adequate frequency. While technology is no longer a limiting factor, economic and management efforts can still be a barrier to high-resolution water quality instrumentation. We propose a new framework to investigate the electrical conductivity (EC) of streamwater, which can be measured continuously through inexpensive sensors. We show that EC embeds information on ion content which can be isolated to retrieve solute concentrations at high resolution. The approach can already be applied to a number of datasets worldwide where water quality campaigns are conducted, provided continuous EC measurements can be collected. The essence of the approach is the decomposition of the EC signal into its "harmonics", i.e. the specific contributions of the major ions which conduct current in water. The ion contribution is used to explore water quality patterns and to develop algorithms that reconstruct solute concentrations during periods where solute measurements are not available. The approach is validated on a hydrochemical dataset from Plynlimon, Wales. Results show that the decomposition of EC is feasible and for at least two major elements the methodology provided improved estimates of high-frequency solute dynamics. Our results support the installation of EC probes to complement water quality campaigns and suggest that the potential of EC measurements in rivers is currently far from being fully exploited.

Spatial and temporal relationships among watershed mining, water quality, and freshwater mussel status in an eastern USA river.

PubMed

Zipper, Carl E; Donovan, Patricia F; Jones, Jess W; Li, Jing; Price, Jennifer E; Stewart, Roger E

2016-01-15

The Powell River of southwestern Virginia and northeastern Tennessee, USA, drains a watershed with extensive coal surface mining, and it hosts exceptional biological richness, including at-risk species of freshwater mussels, downstream of mining-disturbed watershed areas. We investigated spatial and temporal patterns of watershed mining disturbance; their relationship to water quality change in the section of the river that connects mining areas to mussel habitat; and relationships of mining-related water constituents to measures of recent and past mussel status. Freshwater mussels in the Powell River have experienced significant declines over the past 3.5 decades. Over that same period, surface coal mining has influenced the watershed. Water-monitoring data collected by state and federal agencies demonstrate that dissolved solids and associated constituents that are commonly influenced by Appalachian mining (specific conductance, pH, hardness and sulfates) have experienced increasing temporal trends from the 1960s through ~2008; but, of those constituents, only dissolved solids concentrations are available widely within the Powell River since ~2008. Dissolved solids concentrations have stabilized in recent years. Dissolved solids, specific conductance, pH, and sulfates also exhibited spatial patterns that are consistent with dilution of mining influence with increasing distance from mined areas. Freshwater mussel status indicators are correlated negatively with dissolved solids concentrations, spatially and temporally, but the direct causal mechanisms responsible for mussel declines remain unknown. Copyright © 2015 Elsevier B.V. All rights reserved.

Kinetic parameters and nitrate, nitrite changes in bioremediation of Toxic Pentaerythritol Tetranitrate (PETN) contaminated soil

PubMed Central

Sadani, Mohsen; Karami, Mohammad Amin; Teimouri, Fahimeh; Amin, Mohammad Mehdi; Moosavi, Seyed Mahdi; Dehdashti, Bahare

2017-01-01

Background Cleanup of areas contaminated by explosives is a public health concern. Some explosives can be carcinogenic in humans. Pentaerythritol Tetranitrate (PETN), a powerful explosive with very low water solubility, can be easily transported to ground waters. Objective This study was conducted to determine the removal efficiencies of PETN from soil by bioremediation, and obtain kinetic parameters of biological process. Methods This experimental study was conducted at the Environmental Health Engineering Lab (Isfahan University of Medical Sciences, Isfahan, Iran) in 2015–2016. In the present work, bioremediation of the explosive-polluted soils by PETN in anaerobic-aerobic landfarming method was performed. The influence of seeding and biosurfactant addition on bioremediation was also evaluated. The data were analyzed using Microsoft Excel software. Results The results show that, as the initial concentration of PETN increased, the lag phase was increased and the specific growth rate was increased up to 0.1/day in concentration of 50 mg/kg, and then it was decreased to 0.04/day. Subsequent decreases in specific growth rate can cause substrate inhibition. Seeding causes decrease in lag phase significantly. Biosurfactant addition had little to no impact on the length of lag phase, but biosurfactant plus seeding can increase the growth rate to 0.2/day, however, inhibitory effect of the initial concentration was started in very high concentration of PETN (150 mg/kg). Conclusion Biosurfactant addition and seeding together have an impressive effect on biodegradation of PETN, furthermore seeding can enhance active microbial consortium and biosurfactant can improve the poor aqueous solubility of PETN, therefore making the substrate more accessible. PMID:29238507

Long-term immunogenicity and safety of an investigational herpes zoster subunit vaccine in older adults.

PubMed

Chlibek, Roman; Pauksens, Karlis; Rombo, Lars; van Rijckevorsel, Gini; Richardus, Jan H; Plassmann, Georg; Schwarz, Tino F; Catteau, Grégory; Lal, Himal; Heineman, Thomas C

2016-02-03

An investigational subunit vaccine containing the varicella-zoster virus (VZV) glycoprotein E (gE) and the AS01B adjuvant system is being evaluated for the prevention of herpes zoster (HZ) in older adults. A phase II trial evaluating different formulations of this vaccine (containing 25μg, 50μg, or 100μg gE) was conducted in adults ≥60 years of age and showed that all formulations elicited robust cellular and humoral immune responses for up to 3 years after vaccination. In this follow-up study in subjects who received two doses of the 50μg gE/AS01B formulation (HZ/su), we assessed the persistence of the immune responses for up to 6 years after vaccination. This phase II, open-label, multicenter, single-group trial conducted in the Czech Republic, Germany, Sweden, and the Netherlands followed 129 subjects who had received two doses (2 months apart) of HZ/su during the initial trial. Vaccine-induced immune responses (frequencies of gE-specific CD4(+) T cells expressing ≥2 activation markers and serum anti-gE antibody concentrations) were evaluated at 48, 60, and 72 months after the first HZ/su dose. Six years after vaccination with HZ/su, gE-specific cell-mediated immune responses and anti-gE antibody concentrations had decreased by 20-25% from month 36, but remained higher than the prevaccination values. At month 72, the gE-specific cell-mediated immune response was 3.8 times higher than the prevaccination value (477.3 vs. 119.4 activated gE-specific CD4(+) T cells per 10(6) cells), and the anti-gE antibody concentration was 7.3 times higher than the prevaccination value (8159.0 vs. 1121.3mIU/mL). No vaccine-related serious adverse events were reported between months 36 and 72. gE-specific cellular and humoral immune responses persisted for 6 years after two-dose vaccination with HZ/su in healthy older adults. No safety concerns were identified. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

What's New in the Site Characterization Tool Box: Molecular Biological Tools to Identify Microorganisms that Degrade Contaminants and Contaminant-Specific Isotope Analysis to Identify Sources and Document Degradation

EPA Science Inventory

In the past, it was necessary to conduct intensive sampling and monitoring of concentrations of contaminants in ground water to trace plumes back to their true source. Now it is possible to determine the ratio of stable isotopes of carbon, hydrogen or chlorine in the contaminan...

Assessment of the Quality of Life in Families with Children Who Have Intellectual and Developmental Disabilities in Slovenia

ERIC Educational Resources Information Center

Cagran, B.; Schmidt, M.; Brown, I.

2011-01-01

Background: Research was conducted, within the framework of the International Family Quality of Life Project, on the quality of life of families with a member who has a disability. We concentrated on the nine specific domains that the family life measure used, and recorded data from five of its six measurement dimensions: "Importance,…

Trends in Water Quality in the Southeastern United States, 1973-2005

USGS Publications Warehouse

Harned, Douglas A.; Staub, Erik L.; Peak, Kelly L.; Tighe, Kirsten M.; Terziotti, Silvia

2009-01-01

As part of the U.S. Geological Survey National Water-Quality Assessment Program, water-quality data for 334 streams in eight States of the Southeastern United States were assessed for trends from 1973 to 2005. Forty-four U.S. Geological Survey sites were examined for trends in pH, specific conductance, and dissolved oxygen, and in concentrations of dissolved solids, suspended sediment, chloride, sodium, sulfate, silica, potassium, dissolved organic carbon, total nitrogen, total ammonia, total ammonia plus organic nitrogen, dissolved nitrite plus nitrate, and total phosphorus. An additional 290 sites from the U.S. Environmental Protection Agency Storage and Retrieval database were tested for trends in total nitrogen and phosphorus concentrations for the 1975-2004 and 1993-2004 periods. The seasonal Kendall test or Tobit regression was used to detect trends. Concentrations of dissolved constituents have increased in the Southeast during the last 30 years. Specific conductance increased at 62 percent and decreased at 3 percent of the sites, and pH increased at 31 percent and decreased at 11 percent of the sites. Decreasing trends in total nitrogen were detected at 49 percent of the sites, and increasing trends were detected at 10 percent of the sites. Ammonia concentrations decreased at 27 percent of the sites and increased at 6 percent of the sites. Nitrite plus nitrate concentrations increased at 29 percent of the sites and decreased at 10 percent of the sites. These results indicate that the changes in stream nitrogen concentrations generally coincided with improved municipal wastewater-treatment methods. Long-term decreasing trends in total phosphorus were detected at 56 percent of the sites, and increasing trends were detected at 8 percent of the sites. Concentrations of phosphorus have decreased over the last 35 years, which coincided with phosphate-detergent bans and improvements in wastewater treatment that were implemented beginning in 1972. Multiple regression analysis indicated a relation between changes in atmospheric inputs and agricultural practices, and changes in water quality. A long-term water-quality and landscape trends-assessment network for the Southeast is needed to assess changes in water quality over time in response to variations in population, agricultural, wastewater, and landscape variables.

Bacterially Induced Dolomite Formation in the Presence of Sulfate Ions under Aerobic Conditions

NASA Astrophysics Data System (ADS)

Sanchez-Roman, M.; McKenzie, J. A.; Vasconcelos, C.; Rivadeneyra, M.

2005-12-01

The origin of dolomite remains a long-standing enigma in sedimentary geology because, although thermodynamically favorable, precipitation of dolomite from modern seawater does not occur. Experiments conducted at elevated temperatures (200 oC) indicated that the presence of small concentrations of sulfate ions inhibits the transformation of calcite to dolomite [1]. Indeed, sulfate ions appeared to inhibit dolomite formation above 2 mM concentration (versus 28 mM in modern seawater). Recently, culture experiments have demonstrated that sulfate-reducing bacteria mediate the precipitation of dolomite at Earth surface conditions in the presence of sustained sulfate ion concentrations [2,3]. Additionally, in a number of modern hypersaline environments, dolomite forms from solutions with high sulfate ion concentrations (2 to 70 times seawater). These observations suggest that the experimentally observed sulfate-ion inhibition [1] may not apply to all ancient dolomite formation. Here, we report aerobic culture experiments conducted at low temperatures (25 and 35 oC) and variable sulfate ion concentrations (0, 0.5, 1 and 2 x seawater values) using moderately halophilic bacteria, Halomonas meridiana. After an incubation period of 15 days, experiments at 35 oC with variable sulfate ion concentrations (0, 0.5 x and seawater values) contained crystals of Ca-dolomite and stochiometric dolomite. The experiment at 35 oC with 2 x seawater sulfate ion concentration produced dolomite crystals after 20 days of incubation. In a parallel set of experiments at 25 oC, precipitation of dolomite was observed after 25 days of incubation in cultures with variable sulfate ion concentrations (0, 0.5 x and seawater values). In the culture with 2 x seawater sulfate ion concentration, dolomite crystals were observed after 30 days. Our study demonstrates that halophilic bacteria (or heterotrophic microorganisms), which do not require sulfate ions for metabolism, can mediate dolomite precipitation in the presence of sulfate ions. Apparently, microbial dolomite precipitation is not intrinsically linked to any particular group of organisms or specific metabolic processes or even specific environment. Furthermore, because heterotrophic microorganisms appear to be able to mediate microbial dolomite precipitation with or without sulfate ions in the media, our results indicate that the kinetic inhibition effect of sulfate ions can be overcome under specific sedimentary conditions. The present study adds a new insight to the dolomite problem, which could lead to a better clarification of the mechanism(s) involved in the massive dolomite formation observed in the geological record. References: [1] Baker, P.A., and Kastner, M., (1981), Science, 213, 214-216. [2] Vasconcelos, C., McKenzie, J.A., Bernasconi, S., Grujic, D. and Tien, A.J., (1995), Nature 377, 220-222.. [3] Warthmann R., van Lith Y., Vasconcelos C., McKenzie J.A. and Karpoff A.M., (2000), Geology 28, 1091-1094.

Atmospheric Deposition and Surface-Water Chemistry in Mount Rainier and North Cascades National Parks, U.S.A., Water Years 2000 and 2005-2006

USGS Publications Warehouse

Clow, David W.; Campbell, Donald H.

2008-01-01

High-elevation aquatic ecosystems in Mount Rainier and North Cascades National Parks are highly sensitive to atmospheric deposition of nitrogen and sulfur. Thin, rocky soils promote fast hydrologic flushing rates during snowmelt and rain events, limiting the ability of basins to neutralize acidity and assimilate nitrogen deposited from the atmosphere. Potential effects of nitrogen and sulfur deposition include episodic or chronic acidification of terrestrial and aquatic ecosystems. In addition, nitrogen deposition can cause eutrophication of water bodies and changes in species composition in lakes and streams. This report documents results of a study performed by the U.S. Geological Survey, in cooperation with the National Park Service, of the effects of atmospheric deposition of nitrogen and sulfur on surface-water chemistry in Mount Rainier and North Cascades National Parks. Inorganic nitrogen in wet deposition was highest in the vicinity of North Cascades National Park, perhaps due to emissions from human sources and activities in the Puget Sound area. Sulfur in wet deposition was highest near the Pacific coast, reflecting the influence of marine aerosols. Dry deposition generally accounted for less than 30 percent of wet plus dry inorganic nitrogen and sulfur deposition, but occult deposition (primarily fog) represents a potentially substantial unmeasured component of total deposition. Trend analyses indicate inorganic nitrogen in wet deposition was relatively stable during 1986-2005, but sulfur in wet deposition declined substantially during that time, particularly after 2001, when emissions controls were added to a large powerplant in western Washington. Surface-water sulfate concentrations at the study site nearest the powerplant showed a statistically significant decrease between 2000 and 2005-06, but there was no statistically significant change in alkalinity, indicating a delayed response in surface-water alkalinity. Seasonal patterns in surface-water chemistry and streamflow are strongly influenced by melting of seasonal snowpacks, which release large amounts of dilute, slightly acidic water to terrestrial and aquatic ecosystems during spring snowmelt. Concentrations of sulfate, alkalinity, and base cations in surface water declined rapidly during snowmelt, then gradually recovered during summer and fall. Preferential elution of acidic solutes from the snowpack at the beginning of snowmelt may cause episodic acidification in small alpine streams; evidence is provided by a stream sample collected at one of the sites during spring 2006 that was acidic (pH = 4.8, alkalinity = -18 microequivalents per liter) and had high concentrations of nitrate and sulfate and low concentrations of weathering products. Rain-on-snow events caused sharp declines in specific conductance, which was measured continuously using an in-stream sensor. A strong correlation was observed between measured specific conductance and measured alkalinity (r2 = 0.76), permitting estimation of alkalinity from specific-conductance data using a regression equation. Estimated alkalinity declined by an order of magnitude during the rain-on-snow events, in one case to 8 microequivalents per liter. Actual declines in alkalinity might be greater because the regression equation accounts only for dilution effects; at low concentrations, the relation between specific conductance and alkalinity is likely to be nonlinear and have a negative intercept (negative alkalinity). Thus, episodic acidification is possible during rain-on-snow events. The scale of episodic acidification is unknown, but if it occurs, it could have detrimental effects on aquatic life and amphibians. Historical lake-survey data indicate that most lakes are oligotrophic and have low nitrogen and phosphorus concentrations. Nitrogen limitation is more common in lakes in Mount Rainier National Park than in North Cascades National Park due to higher nitrate concentrations at North Cascades. T

Ion-selective optical sensor for continuous on-line monitoring of dialysate sodium during dialysis

NASA Astrophysics Data System (ADS)

Sharma, Manoj K.; Frijns, Arjan J. H.; Mandamparambil, Rajesh; Kooman, Jeroen P.; Smeulders, David M. J.

2017-02-01

Patients with end stage renal disease are dependent on dialysis. In most outpatient centers, the dialysate is prepared with a fixed electrolyte concentration without taking into account the inter-individual differences of essential electrolytes (sodium, potassium and calcium). This one-size fits all approach can lead to acute and chronic cardiovascular complications in dialysis patients. On-line monitoring of these essential electrolytes is an important physiological step towards patient specific dialysate leading to individualized treatment. Currently, changes in electrolyte concentrations are indirectly measured by conductivity measurements, which are not ion- specific. In this paper, we present a novel optical sensor for on-line monitoring of sodium concentrations in dialysate. This sensor is ion-specific and can detect up to a single ion. The working principle is based on the selective fluorescence quenching of photo-induced electron transfer (PET) molecules. The PET molecules when complexed with sodium ions start fluorescing upon laser excitation. The emission intensity is directly correlated to the sodium concentration. To prove the working principle, a micro-optofluidic device has been fabricated in polydimethylsiloxane (PDMS) with integrated optical fibers for fluorescence light collection. The PET molecules are covalently grafted in the PDMS microchannel for continuous monitoring of the sodium dialysate concentrations. The experimental setup consists of a laser module (λ=450nm) operating at 4.5mW, a syringe pump to precisely control the sample flow and a spectrometer for fluorescence collection. The performance of the sensor has been evaluated for sodium ions ranging from 0-50mM. A clear signal and good response time was observed.

Concentrations of organic contaminants detected during managed flow conditions, San Joaquin River and Old River, California, 2001

USGS Publications Warehouse

Orlando, James L.; Kuivila, Kathryn

2005-01-01

Concentrations of organic contaminants were determined in water samples collected at six surface-water sites located along the San Joaquin and Old Rivers during April through June 2001. Water samples were collected, coincident with salmon smolt caging studies conducted by researchers from the Bodega Marine Laboratory at the University of California at Davis to characterize exposure of the salmon smolt to organic contaminants. Sampling occurred prior to, during, and following the implementation of managed streamflow conditions on the San Joaquin and Old Rivers as part of the Vernalis Adaptive Management Plan. Thirteen pesticides were detected in water samples collected during this study, and at least five pesticides were detected in each sample. The total number of pesticide detections varied little between river systems and between sites, but the maximum concentrations of most pesticides occurred in San Joaquin River samples. The total number of pesticides detected varied little over the three time periods. However, during the period of managed streamflow, the fewest number of pesticides were detected at their absolute maximum concentration. Nine wastewater compounds were detected during this study. Suspended-sediment concentrations were similar for the San Joaquin and Old Rivers except during the period of managed streamflow conditions, when suspended-sediment concentration was higher at sites on the San Joaquin River than at sites on the Old River. Values for water parameters (pH, specific conductance, and hardness) were lowest during the period of managed flows.

Carbon-14 Specific Activity Model Validation for Biota in Wetland Environments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yankovich, T.L.; Sharp, K.J.; Benz, M.L.

2008-01-15

In many cases, contaminants, such as radionuclides, can show highly localized spatial distributions in natural systems. Therefore, a key question for environmental assessment and monitoring becomes, how can these localized distributions of contaminants in the environment lead to organism exposure, and ultimately, the potential for effects to receptor biota? To address this question, an important first step is to conduct field surveys at sites of interest to map out the spatial distribution and extent of contaminants in areas that are being occupied and utilized by resident receptor biota. Work can then be conducted to establish predictive relationships between contaminant concentrationsmore » in biota tissues and those in environmental media with which biota interact, to gain an understanding of how representative ambient contaminant concentrations are of biota exposure. The objectives of this study were: - To conduct a field survey in a wetland ecosystem to characterize the spatial distribution of carbon- 14 ({sup 14}C), a radionuclide with dynamics in natural systems that can be described using a specific activity model; and - To determine whether {sup 14}C concentrations in environmental media reflect those measured in tissues of resident flora and fauna. A detailed field campaign was carried out in summer 2001 to characterize the spatial distribution and areal coverage of {sup 14}C in Duke Swamp, a wetland ecosystem on Atomic Energy of Canada Limited (AECL)'s Chalk River Laboratories (CRL) site that receives {sup 14}C through releases from an up-gradient Waste Management Area (WMA), primarily through groundwater influx. Sampling of surface vegetation (dominantly comprised of Sphagnum moss) was conducted at a total of 69 locations, with complementary sampling of air, soil, fungi, aerial insects, ground-dwelling insects, amphibians, small mammals and snakes being carried out at a subset of five locations with varying {sup 14}C concentrations. Concentrations of {sup 14}C in resident Duke Swamp biota were compared to levels measured in environmental media (including moss, soil and air) to determine whether concentrations in such media reflect animal exposure, for application in routine environmental monitoring programs on the CRL site. In general, for most types of receptor animals, {sup 14}C specific activities were found to be similar to or less than those measured in air, soil and surface vegetation at all locations sampled, suggesting that in most cases, estimates of {sup 14}C levels in animals could either be realistically or conservatively predicted based on the values measured in environmental media. In the case of fungi, receptor-to-media {sup 14}C specific activity ratios fell between 0.04 and 0.23 relative to air, between 0.03 and 0.70 relative to soil, and between 0.078 and 0.31 relative to moss. Small mammal specific activities also generally fell well below those that would be predicted based on specific activities measured in environmental media, with ratios ranging from 0.11 to 0.36 relative to air, from 0.17 to 0.85 relative to soil and from 0.21 to 0.58 relative to moss. Similar ratios were also established for snakes; however, a notable exception occurred for amphibians, a type of animal that tends to spend relatively more time in aquatic environments than the other species tested. In the case of Duke Swamp amphibians, animal-to-air {sup 14}C specific activity ratios ranged from 0.40 to 2.3, animal-to-soil ratios ranged from 0.81 to 3.4 and animal-to-moss ratios ranged from 1.5 to 2.4. These higher {sup 14}C levels in amphibians relative to the environmental media may be due to increased {sup 14}C exposure of aquatic or amphibious animals that occupy systems receiving inputs via groundwater. In such systems, {sup 14}C is incorporated in aquatic plants and animals, and later transferred to higher predatory species, such as amphibians, that consume them. Therefore, with the exception of amphibians and other aquatic receptor species, it is reasonable to estimate concentrations of {sup 14}C in receptor biota in wetland environments like Duke Swamp at CRL, based on measurements of {sup 14}C in environmental media, including air, soil and surface vegetation. In the case of Duke Swamp amphibians, environmental media concentrations could still be roughly predicted if they are multiplied by a 4-fold correction factor. In addition, our study findings also confirm that in cases where elevated {sup 14}C levels are highly localized, elevated exposures to resident biota are also highly localized. Such information is critical to the development of cost-effective environmental monitoring programs that are protective of nonhuman biota, while reducing the need to capture and euthanize animals during routine monitoring.« less

Sources, transport, and trends for selected trace metals and nutrients in the Coeur d'Alene and Spokane River Basins, Idaho, 1990-2013

USGS Publications Warehouse

Clark, Gregory M.; Mebane, Christopher A.

2014-01-01

Results from this study indicate that remedial activities conducted since the 1990s have been successful in reducing the concentrations and loads of trace metals in streams and rivers in the Coeur d’Alene and Spokane River Basins. Soils, sediment, surface water, and groundwater in areas of the Coeur d’Alene and Spokane River Basins are contaminated, and the hydrological relations between these media are complex and difficult to characterize. Trace metals have variable source areas, are transported differently depending on hydrologic conditions, and behave differently in response to remedial activities in upstream basins. Based on these findings, no single remedial action would be completely effective in reducing all trace metals to nontoxic concentrations throughout the Coeur d’Alene and Spokane River Basins. Instead, unique cleanup activities targeted at specific media and specific source areas may be necessary to achieve long-term water-quality goals.

Evaluation of weapons' combustion products in armored vehicles. Final report, 30 September 1986-14 December 1988

DOE Office of Scientific and Technical Information (OSTI.GOV)

Menzies, K.T.; Randel, M.A.; Quill, A.L.

1989-01-01

The U.S. Army Biomedical Research and Development Laboratory defined an extensive research program to address the generation of potentially toxic propellant combustion products in crew compartments of armored vehicles during weapons firing. The major objectives of the research were: (1) to determine the presence and concentration of propellant combustion products, (2) to determine potential crew exposure to these combustion products, and (3) to assess the efficacy of field monitoring in armored vehicles. To achieve these goals, air monitoring was conducted in selected armored vehicle types, i.e., M109, M60, M3, M1, at several Army installations. Auxiliary information concerning the specific munitionsmore » fired and the Training and Doctrine Command (TRADOC) or Forces Command (FORSCOM) firing scenarios was collected so that a comparison of pollutant concentrations generated by specific weapons both within vehicle types and between vehicle types could be made.« less

Poverty concentration in an affluent city: Geographic variation and correlates of neighborhood poverty rates in Hong Kong

PubMed Central

Guo, Yingqi; Chang, Shu-Sen; Sha, Feng

2018-01-01

Previous investigations of geographic concentration of urban poverty indicate the contribution of a variety of factors, such as economic restructuring and class-based segregation, racial segregation, demographic structure, and public policy. However, the models used by most past research do not consider the possibility that poverty concentration may take different forms in different locations across a city, and most studies have been conducted in Western settings. We investigated the spatial patterning of neighborhood poverty and its correlates in Hong Kong, which is amongst cities with the highest GDP in the region, using the city-wide ordinary least square (OLS) regression model and the local-specific geographically weighted regression (GWR) model. We found substantial geographic variations in small-area poverty rates and identified several poverty clusters in the territory. Factors found to contribute to urban poverty in Western cities, such as socioeconomic factors, ethnicity, and public housing, were also mostly associated with local poverty rates in Hong Kong. Our results also suggest some heterogeneity in the associations of poverty with specific correlates (e.g. access to hospitals) that would be masked in the city-wide OLS model. Policy aimed to alleviate poverty should consider both city-wide and local-specific factors. PMID:29474393

Poverty concentration in an affluent city: Geographic variation and correlates of neighborhood poverty rates in Hong Kong.

PubMed

Guo, Yingqi; Chang, Shu-Sen; Sha, Feng; Yip, Paul S F

2018-01-01

Previous investigations of geographic concentration of urban poverty indicate the contribution of a variety of factors, such as economic restructuring and class-based segregation, racial segregation, demographic structure, and public policy. However, the models used by most past research do not consider the possibility that poverty concentration may take different forms in different locations across a city, and most studies have been conducted in Western settings. We investigated the spatial patterning of neighborhood poverty and its correlates in Hong Kong, which is amongst cities with the highest GDP in the region, using the city-wide ordinary least square (OLS) regression model and the local-specific geographically weighted regression (GWR) model. We found substantial geographic variations in small-area poverty rates and identified several poverty clusters in the territory. Factors found to contribute to urban poverty in Western cities, such as socioeconomic factors, ethnicity, and public housing, were also mostly associated with local poverty rates in Hong Kong. Our results also suggest some heterogeneity in the associations of poverty with specific correlates (e.g. access to hospitals) that would be masked in the city-wide OLS model. Policy aimed to alleviate poverty should consider both city-wide and local-specific factors.

Exogenous and Endogenous Determinants of Blood Trihalomethane Levels after Showering

PubMed Central

Backer, Lorraine C.; Lan, Qing; Blount, Benjamin C.; Nuckols, J.R.; Branch, Robert; Lyu, Christopher W.; Kieszak, Stephanie M.; Brinkman, Marielle C.; Gordon, Sydney M.; Flanders, W. Dana; Romkes, Marjorie; Cantor, Kenneth P.

2008-01-01

Background We previously conducted a study to assess whether household exposures to tap water increased an individual’s internal dose of trihalomethanes (THMs). Increases in blood THM levels among subjects who showered or bathed were variable, with increased levels tending to cluster in two groups. Objectives Our goal was to assess the importance of personal characteristics, previous exposures, genetic polymorphisms, and environmental exposures in determining THM concentrations in blood after showering. Methods One hundred study participants completed a health symptom questionnaire, a 48-hr food and water consumption diary, and took a 10-min shower in a controlled setting. We examined THM levels in blood samples collected at baseline and 10 and 30 min after the shower. We assessed the significance of personal characteristics, previous exposures to THMs, and specific gene polymorphisms in predicting postshower blood THM concentrations. Results We did not observe the clustering of blood THM concentrations observed in our earlier study. We found that environmental THM concentrations were important predictors of blood THM concentrations immediately after showering. For example, the chloroform concentration in the shower stall air was the most important predictor of blood chloroform levels 10 min after the shower (p < 0.001). Personal characteristics, previous exposures to THMs, and specific polymorphisms in CYP2D6 and GSTT1 genes were significant predictors of both baseline and postshowering blood THM concentrations as well as of changes in THM concentrations associated with showering. Conclusion The inclusion of information about individual physiologic characteristics and environmental measurements would be valuable in future studies to assess human health effects from exposures to THMs in tap water. PMID:18197300

Relationship between cobalamin-dependent metabolites and both serum albumin and alpha1 -proteinase inhibitor concentrations in hypocobalaminemic dogs of 7 different breeds.

PubMed

Grützner, Niels; Suchodolski, Jan S; Steiner, Jörg M

2014-12-01

Increased serum concentrations of homocysteine (HCY) and methylmalonic acid (MMA), the 2 main cobalamin-dependent metabolites, as well as decreased serum albumin and canine alpha1 -proteinase inhibitor (cα1 -PI) concentrations have previously been described in hypocobalaminemic dogs with gastrointestinal disease. However, no studies have been conducted to evaluate potential relationships between these serum biomarkers. The aim of this study was to evaluate the relationship between HCY and MMA, 2 cobalamin-dependent metabolites, and both serum albumin and cα1 -PI concentrations in hypocobalaminemic dogs. Serum samples from 285 dogs including 7 different breeds (Beagle, Boxer, Cocker Spaniel, German Shepherd, Labrador Retriever, Chinese Shar-Pei, and Yorkshire Terrier) with hypocobalaminemia were used. Serum HCY, MMA, albumin, and cα1 -PI concentrations were determined. There was a significant correlation between serum HCY and albumin concentrations, as well as serum HCY and cα1 -PI concentrations (ρ = 0.62 and ρ = 0.37, respectively; P < .0001). No correlations were observed between serum MMA and albumin concentrations, or cα1 -PI concentrations (ρ = 0.01 and ρ = 0.08, respectively; P > .05). In addition, significant breed-specific correlations were observed between serum MMA and albumin concentrations in German Shepherds, and serum HCY and MMA concentrations in Chinese Shar-Peis with hypocobalaminemia. This study shows a correlation between serum albumin and cα1 -PI and HCY concentrations, but not with serum MMA concentration in dogs with hypocobalaminemia. In addition, significant breed-specific correlations were observed between serum MMA and albumin concentrations in German Shepherds, as well as serum HCY and MMA concentrations in Chinese Shar-Peis, emphasizing the unique metabolic interactions in those dog breeds affected by hypocobalaminemia. © 2014 American Society for Veterinary Clinical Pathology.

Aerosol in selected laboratories at Faculty of Mechanical Engineering, Opole University of Technology

NASA Astrophysics Data System (ADS)

Olszowski, Tomasz

2017-10-01

The paper contains the results of a study into mass concentration of the dispersed aerosol fraction with the aerodynamic diameter of up to 2.5 and 10 micrometers. The study was conducted during classes with students participating in them in two laboratories located at Faculty of Mechanical Engineering, Opole University of Technology as well as outdoor outside the building. It was demonstrated that the values of the mass concentration of PM2.5 and PM10 measured in the laboratories differ considerably from the levels measured in the ambient air in the outdoor areas surrounding the faculty building. It was concluded that the diversity of PM2.5/PM10 ratio was greater in the laboratories. Direct correlation was not established between the concentrations of the particular PM fractions in the two investigated environments. It was demonstrated that there is a statistically significant relation between the concentration of PM2.5 and PM10 and the number of people present in the laboratory. The conducted cluster analysis led to the detection of the existence of dominant structures determining air quality parameters. For the analyzed case, endogenic factors are responsible for the aerosanitary condition. The study demonstrated that the evaluation of air quality needs to be performed individually for the specific rooms.

Electrochemical probing of high-level radioactive waste tanks containing washed sludge and precipitates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bickford, D.F.; Congdon, J.W.; Oblath, S.B.

1986-12-01

At the US Department of Energy's Savannah River Plant, corrosion of carbon steel storage tanks containing alkaline, high-level radioactive waste is controlled by specification of limits on waste composition and temperature. Processes for the preparation of waste for final disposal will result in waste with low corrosion inhibitor concentrations and, in some cases, high aromatic organic concentrations, neither of which are characteristic of previous operations. Laboratory tests, conducted to determine minimum corrosion inhibitor levels indicated pitting of carbon steel near the waterline for proposed storage conditions. In situ electrochemical measurements of full-scale radioactive process demonstrations have been conducted to assessmore » the validity of laboratory tests. Probes included pH, Eh (potential relative to a standard hydrogen electrode), tank potential, and alloy coupons. In situ results are compared to those of the laboratory tests, with particular regard given to simulated solution composition. Transition metal hydroxide sludge contains strong passivating species for carbon steel. Washed precipitate contains organic species that lower solution pH and tend to reduce passivating films, requiring higher inhibitor concentrations than the 0.01 molar nitrite required for reactor fuel reprocessing wastes. Periodic agitation, to keep the organic phase suspended, or cathodic protection are possible alternatives to higher nitrite inhibitor concentrations.« less

Influences of water and sediment quality and hydrologic processes on mussels in the Clinch River

USGS Publications Warehouse

Johnson, Gregory C.; Krstolic, Jennifer L.; Ostby, Brett J.K.

2014-01-01

Segments of the Clinch River in Virginia have experienced declining freshwater mussel populations during the past 40 years, while other segments of the river continue to support some of the richest mussel communities in the country. The close proximity of these contrasting reaches provides a study area where differences in climate, hydrology, and historic mussel distribution are minimal. The USGS conducted a study between 2009 and 2011 to evaluate possible causes of the mussel declines. Evaluation of mussel habitat showed no differences in physical habitat quality, leaving water and sediment quality as possible causes for declines. Three years of continuous water-quality data showed higher turbidity and specific conductance in the reaches with low-quality mussel assemblages compared to reaches with high-quality mussel assemblages. Discrete water-quality samples showed higher major ions and metals concentrations in the low-quality reach. Base-flow samples contained high major ion and metal concentrations coincident to low-quality mussel populations. These results support a conceptual model of dilution and augmentation where increased concentrations of major ions and other dissolved constituents from mined tributaries result in reaches with declining mussel populations. Tributaries from unmined basins provide water with low concentrations of dissolved constituents, diluting reaches of the Clinch River where high-quality mussel populations occur.

Sonochemical degradation of ofloxacin in aqueous solutions.

PubMed

Hapeshi, E; Achilleos, A; Papaioannou, A; Valanidou, L; Xekoukoulotakis, N P; Mantzavinos, D; Fatta-Kassinos, D

2010-01-01

The use of low frequency (20 kHz), high energy ultrasound for the degradation of the antibiotic ofloxacin in water was investigated. Experiments were performed with a horn-type ultrasound generator at varying applied power densities (130-640 W/L), drug concentrations (5-20 mg/L), hydrogen peroxide concentrations (0-100 mM) and sparging gases (air, oxygen, nitrogen and argon). In general, conversion (which was assessed following sample absorbance at 288 nm) increased with increasing ultrasound energy and peroxide concentration and decreasing initial drug concentration. Moreover, reactions under an argon atmosphere were faster than with diatomic gases, possibly due to argon's physical properties (e.g. solubility, thermal conductivity and specific heat ratio) favoring sonochemical activity. Overall, low to moderate levels of ofloxacin degradation were achieved (i.e. it never exceeded 50%), thus indicating that radical reactions in the liquid bulk rather than thermal reactions in the vicinity of the cavitation bubble are responsible for ofloxacin degradation.

LEACHATE MIGRATION FROM A SOLID WASTE DISPOSAL FACILITY NEAR BISCAYNE NATIONAL PARK, SOUTH FLORIDA.

USGS Publications Warehouse

Waller, Bradley G.; Labowski, James L.

1987-01-01

Leachate from the Dade County Solid Waste Disposal Facility (SWDF) is migrating to the east (seaward) and to the south from the currently active disposal cell. Water levels and ground-water flow directions are strongly influenced by water-management practices. The SWDF is constructed over the salt-intruded part of the highly transmissive Biscayne aquifer and because of this, chloride ion concentrations and specific conductance levels could not be used as indicators of leachate concentrations. Leachate was detected in multi-depth wells located 75 meters to the south and 20 meters to the east of the active cell. Concentrations of water-quality indicators had mean concentrations generally 2 to 10 times higher than baseline conditions. Primary controls over leachate movement in the SWDF are water-management practices in the Black Creek and Gould Canals, configuration and integrity of the liner beneath the active cell, and low hydraulic gradients in the landfill area.

Hydrologic data and instrumentation, and methods of collecting the data to small watersheds in the coal-mining region of west-central Indiana, October 1980 to June 1983

USGS Publications Warehouse

Renn, D.E.; Duwelius, R.F.; Keeton, C.R.; Tyler, J.W.

1985-01-01

Methods and instrumentation used in collecting samples and measuring concentrations and properties of the following types of data are described in the text: streamflow in seven watersheds; ground-water levels in 46 wells in unconsolidated material and 12 wells in bedrock in or near the watersheds; precipitation in seven watersheds; solar radiation, relative humidity, wind speed, and temperature of air and soil at one location; and pH, specific conductance, temperature of water, and concentrations of selected chemical constituents and suspended sediment in two watersheds.

Microsiemens or Milligrams: Measures of Ionic Mixtures ...

EPA Pesticide Factsheets

In December of 2016, EPA released the Draft Field-Based Methods for Developing Aquatic Life Criteria for Specific Conductivity for public comment. Once final, states and authorized tribes may use these methods to derive field-based ecoregional ambient Aquatic Life Ambient Water Quality Criteria (AWQC) for specific conductivity (SC) in flowing waters. The methods provide flexible approaches for developing science-based SC criteria that reflect ecoregional or state specific factors. The concentration of a dissolved salt mixture can be measured in a number of ways including measurement of total dissolved solids, freezing point depression, refractive index, density, or the sum of the concentrations of individually measured ions. For the draft method, SC was selected as the measure because SC is a measure of all ions in the mixture; the measurement technology is fast, inexpensive, and accurate, and it measures only dissolved ions. When developing water quality criteria for major ions, some stakeholders may prefer to identify the ionic constituents as a measure of exposure instead of SC. A field-based method was used to derive example chronic and acute water quality criteria for SC and two anions a common mixture of ions (bicarbonate plus sulfate, [HCO3−] + [SO42−] in mg/L) that represent common mixtures in streams. These two anions are sufficient to model the ion mixture and SC (R2 = 0.94). Using [HCO3−] + [SO42−] does not imply that these two anions are the

Drought effects on water quality in the South Platte River Basin, Colorado

USGS Publications Warehouse

Sprague, Lori A.

2005-01-01

Twenty-three stream sites representing a range of forested, agricultural, and urban land uses were sampled in the South Platte River Basin of Colorado from July through September 2002 to characterize water quality during drought conditions. With a few exceptions, dissolved ammonia, Kjeldahl nitrogen, total phosphorus, and dissolved orthophosphate concentrations were similar to seasonal historical levels in all land use areas during the drought. At some agricultural sites, decreased dilution of irrigation return flow may have contributed to higher concentrations of some nutrient species, increased primary productivity, and higher dissolved oxygen concentrations. At some urban sites, decreased dilution of base flow and wastewater treatment plant effluent may have contributed to higher dissolved nitrite-plus-nitrate concentrations, increased primary productivity, and higher dissolved oxygen concentrations. Total pesticide concentrations in urban and agricultural areas were not consistently higher or lower during the drought. At most forested sites, decreased dilution of ground water-derived calcium bicarbonate type base flow likely led to elevated pH and specific-conductance values. Water temperatures at many of the forested sites also were higher, contributing to lower dissolved oxygen concentrations during the drought.

Water-quality characteristics in the Black Hills area, South Dakota

USGS Publications Warehouse

Williamson, Joyce E.; Carter, Janet M.

2001-01-01

This report summarizes the water-quality characteristics of ground-water and surface-water in the Black Hills area. Differences in groundwater quality by aquifer and differences in surfacewater quality by water source are presented. Ground-water characteristics are discussed individually for each of the major aquifers in the Black Hills area, referred to herein as the Precambrian, Deadwood, Madison, Minnelusa, Minnekahta, and Inyan Kara aquifers. Characteristics for minor aquifers also are discussed briefly. Surface-water characteristics are discussed for hydrogeologic settings including headwater springs, crystalline core sites, artesian springs, and exterior sites. To characterize the water quality of aquifers and streams in the Black Hills area, data from the U.S. Geological Survey National Water Information System water-quality database were examined. This included samples collected as part of the Black Hills Hydrology Study as well as for other studies within the time frame of October 1, 1930, to September 30, 1998. Tables of individual results are not presented in this report, only summaries. Constituents summarized and discussed include physical properties, common ions, nutrients, trace elements, and radionuclides. Comparisons of concentration levels are made to drinking-water standards as well as beneficial-use and aquatic-life criteria. Ground water within the Black Hills and surrounding area generally is fresh and hard to very hard. Concentrations exceeding various Secondary and Maximum Contaminant Levels may affect the use of the water in some areas for many aquifers within the study area. Concentrations that exceed Secondary Maximum Contaminant Levels (SMCL's) generally affect the water only aesthetically. Radionuclide concentrations may be especially high in some of the major aquifers used within the study area and preclude the use of water in some areas. The sodiumadsorption ratio and specific conductance may affect irrigation use for some wells. High concentrations of iron and manganese are the only concentrations that may hamper the use of water from Precambrian aquifers. The principal deterrents to use of water from the Deadwood aquifer are the high concentrations of radionuclides as well as iron and manganese. Iron, manganese, and hardness may deter use of water from the Madison aquifer as well as dissolved solids and sulfate in downgradient wells (generally deeper than 2,000 feet). Iron, manganese, and hardness may also deter use of the Minnelusa aquifer. Water from the Minnekahta aquifer generally is suitable for all water uses although it is hard to very hard. High concentrations of dissolved solids, iron, sulfate, and manganese may hamper the use of water from the Inyan Kara aquifer. In the southern Black Hills, radium-226 and uranium concentrations also may preclude use of water from the Inyan Kara aquifer. Suitability for irrigation may be affected by high specific conductance and sodium-adsorption ratio for the Inyan Kara. Surface-water quality within the Black Hills and surrounding area generally is very good but the water is hard to very hard. Concentrations of some constituents in the study area tend to be higher exterior to the Black Hills, primarily due to influences from the Cretaceous-age marine shales, including dissolved solids, sodium, sulfate, selenium, and uranium. Headwater springs have relatively constant discharge, specific conductance, dissolved solids, and concentrations of most other constituents. Concentrations at crystalline core sites are very similar to those found in samples from Precambrian aquifers. Some high nitrate concentrations greater than the Maximum Contaminant Level (MCL) of 10 mg/L (milligrams per liter) have occurred at Annie Creek near Lead, which have been attributed to mining impacts. Trace elements generally are low with the exception of arsenic, for which 60 percent of samples exceed the proposed MCL of 10 ug/L (micrograms per liter) and one sample

Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers in a Sand and Gravel Aquifer, Cape Cod, Massachusetts, 1997-2000

USGS Publications Warehouse

Savoie, Jennifer G.; Kent, Douglas B.; Smith, Richard L.; LeBlanc, Denis R.; Hubble, David W.

2004-01-01

Two experimental permeable reactive barriers (PRBs) of granular zero-valent iron were emplaced in the path of a tetrachloroethene plume (the Chemical Spill-10 plume) at the Massachusetts Military Reservation, Cape Cod, Massachusetts, in June 1998. The goal of the field experiment was to achieve emplacement of a granular-iron PRB deeper than attempted before. The PRBs were expected to create a reducing environment and degrade the tetrachloroethene by reductive dechlorination. The goal of the work presented in this report was to observe temporary and sustained changes to the ground-water chemistry downgradient from the PRBs. A hydraulic-fracturing method involving injection of the granular iron with a guar-biopolymer and enzyme slurry was used to install the parallel 30- to 33-foot-wide wall-shaped barriers at a depth of 82 to 113 feet below land surface. An acetic acid and enzyme mixture was subsequently injected in wells near the barriers to degrade the guar biopolymer. Prior to the emplacement, tetrachloroethene concentrations in the Chemical Spill-10 plume at the study area were as high as 250 micrograms per liter. Other water properties in the plume generally were similar to the properties of uncontaminated ground water in the area, which typically has dissolved oxygen concentrations of 250 to 375 micromoles per liter, pH of 5.5 to 6.0, and specific conductance of 60 to 90 microsiemens per centimeter. Water-quality samples were collected periodically from monitoring wells near the PRBs to determine how the emplacement of the granular-iron walls altered the ground-water quality. In addition, an automated well-sampling device measured temperature, specific conductance, pH, and dissolved oxygen every 1?4 days for 16 months in a well downgradient from the two parallel PRBs. Temporary increases (lasting about 5 to 6 months) in specific conductance were observed downgradient from the PRBs as a result of the sodium chloride, potassium carbonate, and other salts included in the slurry and the acetic acid and enzyme mixture that was subsequently injected to degrade the guar biopolymer. Temporary increases in the concentrations of major cations (sodium, potassium, magnesium, and calcium) were observed downgradient from the PRBs, as were temporary but substantial increases in the dissolved and total organic carbon concentrations. Methane was detected, sulfate concentrations decreased temporarily, and concentrations of dissolved inorganic carbon increased in samples from wells downgradient from the PRBs. A sustained (longer than 12 months) reducing environment, in which dissolved oxygen concentrations decreased to zero, the pH increased to about 6.8, and dissolved iron concentrations increased substantially, developed as a result of the oxidation (corrosion) of the granular iron; this zone persisted at least 65 feet downgradient from the PRBs. The pH and dissolved iron concentrations increased with distance from the granular-iron walls. Concentrations of arsenic, cobalt, manganese, and phosphorus increased, and nitrate concentrations were reduced to below the detection limit downgradient from the walls. A sustained decrease of tetrachloroethene concentrations was not observed; however, reductive dechlorination products were observed at wells downgradient from the PRBs during several rounds of sampling. The emplacement of zero-valent iron in the aquifer to remove tetrachloroethene from the ground water caused changes in the water chemistry that persisted farther downgradient from the PRBs than has been observed at other sites because of the low chemical reactivity of the quartz-dominated aquifer sediments and the low ambient dissolved chemical concentrations in the ground water. The small transverse dispersion in the aquifer and the probable long-term persistence of the iron indicate that the chemically altered zone probably will extend a substantial distance downgradient from the PRBs for a substantial period of time (years); fur

Nutrient and carbon availability influences on denitrification in the regulated Lower Colorado River, Austin

NASA Astrophysics Data System (ADS)

Spector, J.

2016-12-01

The Lower Colorado River in Austin, Texas receives nitrogen-rich runoff and treated wastewater effluent and is subject to periodic water releases from the Longhorn Dam, which cause fluctuations in groundwater stage downstream. This research examined groundwater denitrification at the Hornsby Bend riparian area (located approximately 24 km downstream of downtown Austin) and characterized how dam-induced hyporheic exchange affects denitrification rates. Conductivity, temperature, water level, and dissolved oxygen concentrations were measured continuously throughout flood pulses for six months using dataloggers installed in a transect of seven monitoring wells on the river bank. Hourly samples were collected using an autosampler in one monitoring well (MW-5) during various flood conditions during the six month monitoring period. Water samples were analyzed for total organic carbon, total nitrogen, anions (NO3- and NO2-), NH4+ concentrations, alkalinity, and specific ultraviolet absorbance (SUVA) to characterize dissolved organic matter. Following large flood events (up to 4 m of water level stage increase), average conductivity increased 300 µs/centimeter in MW-5 as the water level receded. Analysis of water samples indicated that NO3- reduction occurred as conductivity and alkalinity increased. In addition, NH4+ concentrations increased during high conductivity periods. Increased denitrification activity corresponded with high SUVA. High conductivity and alkalinity increase the availability of electron donors (HCO3- and CO32-) and enhances denitrification potential. Higher SUVA values indicate increased dissolved organic carbon aromaticity and corresponding NO3- reduction. Additionally, changes in dissolved organic matter lability indicate the residence times of possible reactive organic carbon in the riparian area. This study has implications for determining advantageous geochemical conditions for hyporheic zone denitrification following large flood events.

Electrically conductive ZnO/GaN distributed Bragg reflectors grown by hybrid plasma-assisted molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Hjort, Filip; Hashemi, Ehsan; Adolph, David; Ive, Tommy; Haglund, Àsa

2017-02-01

III-nitride-based vertical-cavity surface-emitting lasers have so far used intracavity contacting schemes since electrically conductive distributed Bragg reflectors (DBRs) have been difficult to achieve. A promising material combination for conductive DBRs is ZnO/GaN due to the small conduction band offset and ease of n-type doping. In addition, this combination offers a small lattice mismatch and high refractive index contrast, which could yield a mirror with a broad stopband and a high peak reflectivity using less than 20 DBR-pairs. A crack-free ZnO/GaN DBR was grown by hybrid plasma-assisted molecular beam epitaxy. The ZnO layers were approximately 20 nm thick and had an electron concentration of 1×1019 cm-3, while the GaN layers were 80-110 nm thick with an electron concentration of 1.8×1018 cm-3. In order to measure the resistance, mesa structures were formed by dry etching through the top 3 DBR-pairs and depositing non-annealed Al contacts on the GaN-layers at the top and next to the mesas. The measured specific series resistance was dominated by the lateral and contact contributions and gave an upper limit of 10-3Ωcm2 for the vertical resistance. Simulations show that the ZnO electron concentration and the cancellation of piezoelectric and spontaneous polarization in strained ZnO have a large impact on the vertical resistance and that it could be orders of magnitudes lower than what was measured. This is the first report on electrically conductive ZnO/GaN DBRs and the upper limit of the resistance reported here is close to the lowest values reported for III-nitride-based DBRs.

Physical-property, water-quality, plankton, and bottom-material data for Devils Lake and East Devils Lake, North Dakota, September 1988 through October 1990

USGS Publications Warehouse

Sando, Steven K.; Sether, Bradley A.

1993-01-01

Physical-properties were measured and water-quality, plankton, and bottom-material samples were collected at 10 sites in Devils Lake and East Devils Lake during September 1988 through October 1990 to study water-quality variability and water-quality and plankton relations in Devils Lake and East Devils Lake. Physical properties measured include specific conductance, pH, water temperature, dissolved-oxygen concentration, water transparency, and light transmission. Water-quality samples were analyzed for concentrations of major ions, selected nutrients, and selected trace elements. Plankton samples were examined for identification and enumeration of phytoplankton and zooplankton species, and bottom-material samples were analyzed for concentrations of selected nutrients. Data-collection procedures are discussed and the data are presented in tabular form.

Physical, chemical, and biological data for two sites on the upper Kenai River, Alaska, 1998

USGS Publications Warehouse

Dorava, Joseph M.; Ness, Lee

1999-01-01

Water-quality data were collected and stream characteristics were documented from two sites along the upper Kenai River in the Kenai National Wildlife Refuge, Alaska. These data were collected to describe the current status of the sites and to provide baseline information from which changes in the future could be evaluated. Physical characteristics included channel geometry surveys, and measurements of channel widths and water discharge at each site. Chemical data included stream water temperature, dissolved-oxygen concentration, pH, specific conductance, E. coli and fecal coliform counts, and nutrient concentration. Data on concentrations of trace elements and various organic compounds in bed sediments and the tissue of slimy sculpin were also collected. Biological characteristics were evaluated using measurements of the bacteria, benthic macroinvertebrate, and fish communities.

A computer program for geochemical analysis of acid-rain and other low-ionic-strength, acidic waters

USGS Publications Warehouse

Johnsson, P.A.; Lord, D.G.

1987-01-01

ARCHEM, a computer program written in FORTRAN 77, is designed primarily for use in the routine geochemical interpretation of low-ionic-strength, acidic waters. On the basis of chemical analyses of the water, and either laboratory or field determinations of pH, temperature, and dissolved oxygen, the program calculates the equilibrium distribution of major inorganic aqueous species and of inorganic aluminum complexes. The concentration of the organic anion is estimated from the dissolved organic concentration. Ionic ferrous iron is calculated from the dissolved oxygen concentration. Ionic balances and comparisons of computed with measured specific conductances are performed as checks on the analytical accuracy of chemical analyses. ARCHEM may be tailored easily to fit different sampling protocols, and may be run on multiple sample analyses. (Author 's abstract)

Experimental evaluation of the thermal properties of two tissue equivalent phantom materials.

PubMed

Craciunescu, O I; Howle, L E; Clegg, S T

1999-01-01

Tissue equivalent radio frequency (RF) phantoms provide a means for measuring the power deposition of various hyperthermia therapy applicators. Temperature measurements made in phantoms are used to verify the accuracy of various numerical approaches for computing the power and/or temperature distributions. For the numerical simulations to be accurate, the electrical and thermal properties of the materials that form the phantom should be accurately characterized. This paper reports on the experimentally measured thermal properties of two commonly used phantom materials, i.e. a rigid material with the electrical properties of human fat, and a low concentration polymer gel with the electrical properties of human muscle. Particularities of the two samples required the design of alternative measuring techniques for the specific heat and thermal conductivity. For the specific heat, a calorimeter method is used. For the thermal diffusivity, a method derived from the standard guarded comparative-longitudinal heat flow technique was used for both materials. For the 'muscle'-like material, the thermal conductivity, density and specific heat at constant pressure were measured as: k = 0.31 +/- 0.001 W(mK)(-1), p = 1026 +/- 7 kgm(-3), and c(p) = 4584 +/- 107 J(kgK)(-1). For the 'fat'-like material, the literature reports on the density and specific heat such that only the thermal conductivity was measured as k = 0.55 W(mK)(-1).

A Review of Strategic Mobility Models and Analysis

DTIC Science & Technology

1991-01-01

Logistics Directorate of the Joint Staff, (JS-J-4) specifically by the Studies , Concepts, and Analysis Division (SCAD), which conducts long-range...their analysis objec- tives. This study was designed to assist the Logistics Directorate of the Joint Staff (JS/J-4) to understand and improve the...This study concentrated on resource planning, which is the type of planning performed by the Logistics Directorate’s Studies , Concepts, and Analysis

Geochemistry of altered and mineralized rocks from the Morey and Fandango Wilderness Study Areas, northern Hot Creek Range, Nye County, Nevada

USGS Publications Warehouse

Nash, J.T.; John, D.A.; Malcolm, M.J.; Briggs, P.H.; Crock, J.G.

1986-01-01

The U.S. Geological Survey and the St. Johns River Water Management District are investigating the hydrogeology of the Floridan aquifer system. An essential element of this investigation is the design and construction of a monitor well network in the lower saline water-bearing zone which occurs at about 2,000 ft below land surface. During 1985, a well near Ponte Vedra in northeast St. Johns County was completed into the lower saline water-bearing zone at a depth of 1,980 to 2,035 ft below land surface. This well and other wells drilled under this or other programs will be used to monitor water levels and water chemistry of the lower saline zone. Chloride concentrations in water above the lower saline zone ranged from 14 to 270 mg/L and specific conductance ranged from 450 to 1,440 micromhos/cm c. In the lower zone, chloride concentrations were as much as 16,210 mg/L and specific conductance as much as 46,000 micromhos per centimeter. Aquifer head and artesian flow from the well generally increased with depth. Water temperatures also increased from 23 C in the upper part of the aquifer to more than 28 C in the lower saline zone. (USGS)

Dissolved Strontium and Barium in Fresh and Saltwater: a 2-year Study in the Calcasieu River to the Gulf of Mexico

NASA Astrophysics Data System (ADS)

He, S.; Xu, Y. J.

2016-02-01

Strontium and barium to calcium ratios are often used as proxies for tracking animal movement across salinity gradients. As sea level rise continues, many estuarine rivers face saltwater intrusion, which may cause changes in mobility and distribution of these metals upstream. Despite intensive research on metal adsorption and desorption in marine systems, knowledge of the spatiotemporal distribution of these elements along estuarine rivers is still limited. In this study, we conducted an intensive monitoring of Sr and Ba dynamics along an 88-km long estuary, the Calcasieu River, which has been strongly affected by saltwater intrusion. Over the period from May 2013 to July 2015, we collected monthly water samples and performed in-situ water quality measurements at six sites from the upstream to the river mouth. Water samples were analyzed for dissolved Sr, Ba, and Ca concentrations. In-situ measurements of salinity, pH, water temperature, dissolved oxygen concentration, and specific conductance were taken. Our preliminary data showed that the Sr and Ca concentrations and the Sr/Ca ratio all increased significantly with decreasing distance to the Gulf of Mexico, while the Ba/Ca ratio decreased with decreasing distance to the Gulf. The spatial variation in Ba concentration was marginal. The Sr and Ca concentrations and ratios were positively related to salinity, while Ba/Ca was negatively related to salinity. All the elemental concentrations and ratios had considerable seasonal and interannual variations. There were significant differences among sampling months for all the elemental concentrations and ratios (p<0.05), and there were significant differences among sampling years for the Sr and Ca concentrations and the Ba/Ca ratio (p<0.05).

An evaluation of water-quality data obtained at four streamflow daily-record stations in Idaho

USGS Publications Warehouse

Dyer, Kenneth L.

1973-01-01

Chemical data for four stream-gaging stations in Idaho, each having 6 to 22 years of available records, were analyzed to determine functional relations between concentrations of the major inorganic constituents, specific conductance, and stream discharge. Three of the four stations had sufficient available record for assessing changes in constituent relations with time. The records for each long-term station were subdivided into segments of approximately 5 years each. Plots and regression equations were derived for each record segment to show the relations of each major constituent value to levels of specific conductance and stream discharge. At only one stations, Boise River at Notus, was there was an apparent significant change in chemical characteristics with time. Between 1940 and 1951, the percentages of chloride and sulfate in solution at this station declined appreciably and were largely replaced by bicarbonate. In general, there were highly significant correlations between the major inorganic ions and specific conductance, although those observed at Bear River at Border were distinctly poorer than those observed for the other stations. Corresponding correlations between the major ions and discharge were almost always less significant than those observed between the same ions and specific conductance. The common ion-discharge relations observed on the Snake River near Heise were more highly correlated before 1957 than thereafter--probably because of changes induced by the construction of Palisades Dam. A similar decline in correlation of common ion-discharge relations was observed at the Snake River at King Hill station after 1957, and this also might be attributable to changes in water regulation at various upstream impoundments.

Development of a human-specific B. thetaiotaomicron IMS ...

EPA Pesticide Factsheets

Immunomagnetic separation/adenosine triphosphate (IMS/ATP) assays utilize paramagnetic beads and target-specific antibodies to isolate target organisms. Following isolation, adenosine tri-phosphate (ATP) is extracted from the target population and quantified. An inversely-coupled (Inv-IMS/ATP)assay for detection of Bacteroides thetaiotaomicron was developed and applied for rapid detection of human-associated fecal contamination in surface waters in Baja California. Specificity of the assay was tested against challenge solutions of varying concentrations of dog, gull, horse and chicken feces, and a field validation survey of coastal and WWTP effluent water quality in Rosarito and Enseneda, Baja California was conducted. Inv IMS/ATP measurements made shown to be specific and sensitive to human fecal contamination. At test concentrations of less than 1000 MPN ENT/100 mL, sensitivity and specificity of the assay both exceeded 80%. Moreover, the Inv-IMS/ATP assay yielded measurements of viable B. thetaiotaomicron that were comparable to the HF183 human marker in complex surface waters impacted with both wastewater and runoff, and the Inv-IMS/ATP assay was able to effectively differentiate between surface waters impacted with adequately and inadequately treated wastewater. The Inv-IMS/ATP assays shows promise for rapid evaluation of recreational water quality in areas where access to more expensive methods is limited and in areas where water quality in unpredicta

Association between worldwide dietary and lifestyle patterns with total cholesterol concentrations and DALYs for infectious and cardiovascular diseases: an ecological analysis.

PubMed

Oggioni, C; Cena, H; Wells, J C K; Lara, J; Celis-Morales, C; Siervo, M

2015-12-01

Global dietary and lifestyle trends are primary risk factors for communicable and non-communicable diseases. An ecological analysis was conducted to examine the association of global dietary and lifestyle patterns with total cholesterol concentrations. This study also investigated whether total cholesterol modified the association between dietary and lifestyle habits with disability-adjusted-life-years-lost (DALYs) for infectious and cardiovascular diseases (CVDs). Country-specific mean total cholesterol concentrations and DALYs for infectious and CVDs were obtained. Data were then matched to country-specific food and energy availability for consumption and information on obesity, physical inactivity, urbanization, gross domestic product (GDP), life expectancy and smoking. Stepwise multiple regression models were developed to identify significant predictors of total cholesterol concentrations and DALYs for infectious and CVDs. Life expectancy and egg and meat consumption were significantly associated with cholesterol concentrations. DALYs for infectious diseases were associated with smoking, life expectancy and per capita GDP. Smoking was the only predictor of DALYs for CVDs. The improvement of socio-demographic conditions and economic growth is likely to reduce the burden of communicable diseases in developing countries. A concurring increase in non-communicable diseases is expected, and these results have, yet again, identified smoking as a primary risk factor for CVDs. Copyright © 2015 Ministry of Health, Saudi Arabia. Published by Elsevier Ltd. All rights reserved.

CSF soluble amyloid precursor proteins in the diagnosis of incipient Alzheimer disease.

PubMed

Perneczky, R; Tsolakidou, A; Arnold, A; Diehl-Schmid, J; Grimmer, T; Förstl, H; Kurz, A; Alexopoulos, P

2011-07-05

To explore if soluble amyloid precursor proteins (sAPP) in CSF improve the identification of patients with incipient Alzheimer disease (AD) in a group of patients with mild cognitive impairment (MCI). A cohort study with follow-up assessments of 58 patients with MCI with baseline CSF sampling was conducted: 21 patients had progressed to probable AD (MCI-AD), 27 still had MCI, 8 had reverted to normal (MCI-NAD), and 2 patients with frontotemporal dementia (FTD) were excluded. Sixteen additional patients with FTD were included to explore the specificity of the CSF markers. CSF concentrations of sAPPα, sAPPβ, tau, and Aβ(1-42) were measured with sensitive and specific ELISAs. Associations between diagnostic status, CSF protein concentrations, and other patient characteristics were explored using multiple logistic regression analyses with stepwise variable selection. The optimal sensitivity and specificity of the best models were derived from receiver operating characteristic curves. The MCI-AD group had significantly higher sAPPβ concentrations than the MCI-NAD and the FTD groups. A combination of sAPPβ, tau, and age differentiated the MCI-AD and the MCI-NAD groups with a sensitivity of 80.00% and a specificity of 81.00%. The best model for the differentiation of the MCI-AD and the FTD groups included sAPPβ and tau, and showed a sensitivity of 95.20% and a specificity of 81.20%. Aβ(1-42) and sAPPα did not significantly contribute to the models. These findings suggest that sAPPβ may be clinically useful, and superior to Aβ(1-42), in the early and differential diagnosis of incipient AD.

Streamflow, Water Quality, and Constituent Loads and Yields, Scituate Reservoir Drainage Area, Rhode Island,Water Year 2002

USGS Publications Warehouse

Breault, Robert F.

2009-01-01

Streamflow and water-quality data were collected by the U.S. Geological Survey (USGS) or the Providence Water Supply Board, Rhode Island's largest drinking-water supplier. Streamflow was measured or estimated by the USGS following standard methods at 23 streamflow-gaging stations; 10 of these stations were also equipped with instrumentation capable of continuously monitoring specific conductance. Streamflow and concentrations of sodium and chloride estimated from records of specific conductance were used to calculate instantaneous (15-minute) loads of sodium and chloride during water year (WY) 2002 (October 1, 2001 to September 30, 2002). Water-quality samples were also collected at 35 of 37 sampling stations in the Scituate Reservoir drainage area by the Providence Water Supply Board during WY 2002 as part of a long-term sampling program. Water-quality data are summarized by using values of central tendency and are used, in combination with measured (or estimated) streamflows, to calculate loads and yields (loads per unit area) of selected water-quality constituents for WY 2002. The largest tributary to the reservoir (the Ponaganset River, which was monitored by the USGS) contributed about 12.6 cubic feet per second (ft3/s) to the reservoir during WY 2002. For the same time period, annual mean streamflows measured (or estimated) for the other monitoring stations in this study ranged from about 0.14 to 8.1 ft3/s. Together, tributary streams (equipped with instrumentation capable of continuously monitoring specific conductance) transported about 534,000 kilograms (kg) of sodium and 851,000 kg of chloride to the Scituate Reservoir during WY 2002; sodium and chloride yields for the tributaries ranged from 2,900 to 40,200 kilograms per square mile (kg/mi2) and from 4,200 to 68,200 kg/mi2, respectively. At the stations where water-quality samples were collected by the Providence Water Supply Board, the median of the median chloride concentrations was 16.8 milligrams per liter (mg/L), median nitrate concentration was 0.02 mg/L as N, median nitrite concentration was 0.002 mg/L as N, median orthophosphate concentration was 0.03 mg/L as P, and median concentrations of total coliform and Escherichia coli (E. coli) bacteria were 22 and 14 colony forming units per 100 milliliters (CFU/100 mL), respectively. The medians of the median daily loads (and yields) of chloride, nitrate, nitrite, orthophosphate and total coliform and E. coli bacteria were 21 kg/d (12 kg/d/mi2), 0.04 kg/d (0.014 kg/d/mi2), 0.005 kg/d (0.002 kg/d/mi2), 0.08 kg/d (0.035 kg/d/mi2), and 370 million colony forming units per day (CFUx106/d) (120 CFUx106/d/ mi2) and 300 CFUx106/d (75 CFUx106/d/mi2), respectively.

Streamflow, Water Quality, and Constituent Loads and Yields, Scituate Reservoir Drainage Area, Rhode Island, Water Year 2006

USGS Publications Warehouse

Breault, Robert F.; Campbell, Jean P.

2010-01-01

Streamflow and water-quality data were collected by the U.S. Geological Survey (USGS) or the Providence Water Supply Board, Rhode Island's largest drinking-water supplier. Streamflow was measured or estimated by the USGS following standard methods at 23 streamgage stations; 10 of these stations were also equipped with instrumentation capable of continuously monitoring specific conductance. Streamflow and concentrations of sodium and chloride estimated from records of specific conductance were used to calculate instantaneous (15-minute) loads of sodium and chloride during water year (WY) 2006 (October 1, 2005, to September 30, 2006). Water-quality samples were also collected at 37 sampling stations in the Scituate Reservoir drainage area by the Providence Water Supply Board during WY 2006 as part of a long-term sampling program. Water-quality data are summarized by using values of central tendency and are used, in combination with measured (or estimated) streamflows, to calculate loads and yields (loads per unit area) of selected water-quality constituents for WY 2006. The largest tributary to the reservoir (the Ponaganset River, which was monitored by the USGS) contributed about 42 cubic feet per second (ft3/s) to the reservoir during WY 2006. For the same time period, annual mean streamflows1 measured (or estimated) for the other monitoring stations in this study ranged from about 0.60 to 26 ft3/s. Together, tributary streams (equipped with instrumentation capable of continuously monitoring specific conductance) transported about 1,600,000 kilograms (kg) of sodium and 2,500,000 kg of chloride to the Scituate Reservoir during WY 2006; sodium and chloride yields for the tributaries ranged from 15,000 to 100,000 kilograms per square mile (kg/mi2) and from 22,000 to 180,000 kg/mi2, respectively. At the stations where water-quality samples were collected by the Providence Water Supply Board, the median of the median chloride concentrations was 24.6 milligrams per liter (mg/L), median nitrite concentration was 0.001 mg/L as N, median nitrate concentration was 0.02 mg/L as N, median orthophosphate concentration was 0.07 mg/L as P, and median concentrations of total coliform and Escherichia coli (E. coli) bacteria were 43 and 23 colony forming units per 100 milliliters (CFU/100 mL), respectively. The medians of the median daily loads (and yields) of chloride, nitrite, nitrate, orthophosphate, and total coliform and E. coli bacteria were 230 kg/d (81 kg/d/mi2), 17 g/d (4.4 g/d/mi2), 130 g/d (50 g/d/mi2), 470 g/d (210 g/d/mi2), and 2,100 million colony forming units per day (CFU?106/d) (1,300 CFU?106/d/mi2) and 670 CFU?106/d (420 CFU?106/d/mi2), respectively. 1The arithmetic mean of the individual daily mean discharges for the year noted or for the designated period.

Streamflow, Water Quality, and Constituent Loads and Yields, Scituate Reservoir Drainage Area, Rhode Island, Water Year 2005

USGS Publications Warehouse

Breault, Robert F.; Campbell, Jean P.

2010-01-01

Streamflow and water-quality data were collected by the U.S. Geological Survey (USGS) or the Providence Water Supply Board, Rhode Island’s largest drinking-water supplier. Streamflow was measured or estimated by the USGS following standard methods at 23 streamgage stations; 10 of these stations were also equipped with instrumentation capable of continuously monitoring specific conductance. Streamflow and concentrations of sodium and chloride estimated from records of specific conductance were used to calculate instantaneous (15-minute) loads of sodium and chloride during water year (WY) 2005 (October 1, 2004, to September 30, 2005). Water-quality samples were also collected at 37 sampling stations in the Scituate Reservoir drainage area by the Providence Water Supply Board during WY 2005 as part of a long-term sampling program. Water-quality data are summarized by using values of central tendency and are used, in combination with measured (or estimated) streamflows, to calculate loads and yields (loads per unit area) of selected water-quality constituents for WY 2005. The largest tributary to the reservoir (the Ponaganset River, which was monitored by the USGS) contributed about 30 cubic feet per second (ft3/s) to the reservoir during WY 2005. For the same time period, annual mean streamflows1 measured (or estimated) for the other monitoring stations in this study ranged from about 0.42 to 19 ft3/s. Together, tributary streams (equipped with instrumentation capable of continuously monitoring specific conductance) transported about 1,300,000 kilograms (kg) of sodium and 2,000,000 kg of chloride to the Scituate Reservoir during WY 2005; sodium and chloride yields for the tributaries ranged from 13,000 to 77,000 kilograms per square mile (kg/mi2) and from 19,000 to 130,000 kg/mi2, respectively. At the stations where water-quality samples were collected by the Providence Water Supply Board, the median of the median chloride concentrations was 25.3 milligrams per liter (mg/L), median nitrite concentration was 0.002 mg/L as N, median nitrate concentration was 0.02 mg/L as N, median orthophosphate concentration was 0.07 mg/L as P, and median concentrations of total coliform and Escherichia coli (E. coli) bacteria were 23 and 15 colony forming units per 100 milliliters (CFU/100 mL), respectively. The medians of the median daily loads (and yields) of chloride, nitrite, nitrate, orthophosphate, and total coliform and E. coli bacteria were 230 kg/d (93 kg/d/mi2), 16 g/d (6.1 g/d/mi2), 150 g/d (71 g/d/mi2), 530 g/d (250 g/d/mi2), and 1,500 million colony forming units per day (CFU×106/d) (630 CFU×106/d/mi2) and 420 CFU×106/d (290 CFU×106/d/mi2), respectively. 1The arithmetic mean of the individual daily mean discharges for the year noted or for the designated period.

Streamflow, water quality, and constituent loads and yields, Scituate Reservoir drainage area, Rhode Island, water year 2010

USGS Publications Warehouse

Smith, Kirk P.; Breault, Robert F.

2011-01-01

Streamflow and water-quality data were collected by the U.S. Geological Survey (USGS) or the Providence Water Supply Board (PWSB), Rhode Island's largest drinking-water supplier. Streamflow was measured or estimated by the USGS following standard methods at 23 streamgages; 14 of these stations were also equipped with instrumentation capable of continuously monitoring specific conductance and water temperature. Streamflow and concentrations of sodium and chloride estimated from records of specific conductance were used to calculate loads of sodium and chloride during water year (WY) 2010 (October 1, 2009, to September 30, 2010). Water-quality samples also were collected at 37 sampling stations by the PWSB and at 14 monitoring stations by the USGS during WY 2010 as part of a long sampling program; all stations are in the Scituate Reservoir drainage area. Waterquality data collected by PWSB are summarized by using values of central tendency and are used, in combination with measured (or estimated) streamflows, to calculate loads and yields (loads per unit area) of selected water-quality constituents for WY 2010. The largest tributary to the reservoir (the Ponaganset River, which was monitored by the USGS) contributed a mean streamflow of about 39 cubic feet per second (ft3/s) to the reservoir during WY 2010. For the same time period, annual mean streamflows measured (or estimated) for the other monitoring stations in this study ranged from about 0.7 to 27 ft3/s. Together, tributary streams (equipped with instrumentation capable of continuously monitoring specific conductance) transported about 1,500,000 kilograms (kg) of sodium and 2,500,000 kg of chloride to the Scituate Reservoir during WY 2010; sodium and chloride yields for the tributaries ranged from 11,000 to 66,000 kilograms per square mile (kg/mi2) and from 18,000 to 110,000 kg/mi2, respectively. At the stations where water-quality samples were collected by the PWSB, the median of the median chloride concentrations was 20.2 milligrams per liter (mg/L), median nitrite concentration was 0.002 mg/L as nitrogen (N), median nitrate concentration was 0.01 mg/L as N, median orthophosphate concentration was 0.06 mg/L as phosphorus, and median concentrations of total coliform and Escherichia coli (E. coli) bacteria were 93 and 16 colony forming units per 100 milliliters (CFU/100mL), respectively. The medians of the median daily loads (and yields) of chloride, nitrite, nitrate, orthophosphate, and total coliform and E. coli bacteria were 170 kg/d (73 kg/d/mi2), 11 g/d (5.3 g/d/mi2), 74 g/d (39 g/d/mi2), 340 g/d (170 g/d/mi2), 5,700 million colony forming units per day (CFUx106/d) (2,300 CFUx106/d/mi2), and 620 CFUx106/d (440 CFUx106/d/mi2), respectively.

Continuous water-quality monitoring and regression analysis to estimate constituent concentrations and loads in the Red River of the North, Fargo, North Dakota, 2003-05

USGS Publications Warehouse

Ryberg, Karen R.

2006-01-01

This report presents the results of a study by the U.S. Geological Survey, done in cooperation with the Bureau of Reclamation, U.S. Department of the Interior, to estimate water-quality constituent concentrations in the Red River of the North at Fargo, North Dakota. Regression analysis of water-quality data collected in 2003-05 was used to estimate concentrations and loads for alkalinity, dissolved solids, sulfate, chloride, total nitrite plus nitrate, total nitrogen, total phosphorus, and suspended sediment. The explanatory variables examined for regression relation were continuously monitored physical properties of water-streamflow, specific conductance, pH, water temperature, turbidity, and dissolved oxygen. For the conditions observed in 2003-05, streamflow was a significant explanatory variable for all estimated constituents except dissolved solids. pH, water temperature, and dissolved oxygen were not statistically significant explanatory variables for any of the constituents in this study. Specific conductance was a significant explanatory variable for alkalinity, dissolved solids, sulfate, and chloride. Turbidity was a significant explanatory variable for total phosphorus and suspended sediment. For the nutrients, total nitrite plus nitrate, total nitrogen, and total phosphorus, cosine and sine functions of time also were used to explain the seasonality in constituent concentrations. The regression equations were evaluated using common measures of variability, including R2, or the proportion of variability in the estimated constituent explained by the regression equation. R2 values ranged from 0.703 for total nitrogen concentration to 0.990 for dissolved-solids concentration. The regression equations also were evaluated by calculating the median relative percentage difference (RPD) between measured constituent concentration and the constituent concentration estimated by the regression equations. Median RPDs ranged from 1.1 for dissolved solids to 35.2 for total nitrite plus nitrate. Regression equations also were used to estimate daily constituent loads. Load estimates can be used by water-quality managers for comparison of current water-quality conditions to water-quality standards expressed as total maximum daily loads (TMDLs). TMDLs are a measure of the maximum amount of chemical constituents that a water body can receive and still meet established water-quality standards. The peak loads generally occurred in June and July when streamflow also peaked.

Granular activated carbon adsorption of organic micro-pollutants in drinking water and treated wastewater--Aligning breakthrough curves and capacities.

PubMed

Zietzschmann, Frederik; Stützer, Christian; Jekel, Martin

2016-04-01

Small-scale granular activated carbon (GAC) tests for the adsorption of organic micro-pollutants (OMP) were conducted with drinking water and wastewater treatment plant (WWTP) effluent. In both waters, three influent OMP concentration levels were tested. As long as the influent OMP concentrations are below certain thresholds, the relative breakthrough behavior is not impacted in the respective water. Accordingly, the GAC capacity for OMP is directly proportional to the influent OMP concentration in the corresponding water. The differences between the OMP breakthrough curves in drinking water and WWTP effluent can be attributed to the concentrations of the low molecular weight acid and neutral (LMW) organics of the waters. Presenting the relative OMP concentrations (c/c0) over the specific throughput of the LMW organics (mg LMW organics/g GAC), the OMP breakthrough curves in drinking water and WWTP effluent superimpose each other. This superimposition can be further increased if the UV absorbance at 254 nm (UV254) of the LMW organics is considered. In contrast, using the specific throughput of the dissolved organic carbon (DOC) did not suffice to obtain superimposed breakthrough curves. Thus, the LMW organics are the major water constituent impacting OMP adsorption onto GAC. The results demonstrate that knowing the influent OMP and LMW organics concentrations (and UV254) of different waters, the OMP breakthroughs and GAC capacities corresponding to any water can be applied to all other waters. Copyright © 2016 Elsevier Ltd. All rights reserved.

Environmental exposures and health impacts of PFAS ...

EPA Pesticide Factsheets

Environmental exposures and health impacts of PFAS The National Exposure Research Laboratory (NERL) Human Exposure and Atmospheric Sciences Division (HEASD) conducts research in support of EPA mission to protect human health and the environment. HEASD research program supports Goal 1 (Clean Air) and Goal 4 (Healthy People) of EPA strategic plan. More specifically, our division conducts research to characterize the movement of pollutants from the source to contact with humans. Our multidisciplinary research program produces Methods, Measurements, and Models to identify relationships between and characterize processes that link source emissions, environmental concentrations, human exposures, and target-tissue dose. The impact of these tools is improved regulatory programs and policies for EPA.

Marine predators and persistent prey in the southeast Bering Sea

NASA Astrophysics Data System (ADS)

Sigler, Michael F.; Kuletz, Kathy J.; Ressler, Patrick H.; Friday, Nancy A.; Wilson, Christopher D.; Zerbini, Alexandre N.

2012-06-01

Predictable prey locations reduce search time and energetic costs of foraging; thus marine predators often exploit locations where prey concentrations persist. In our study, we examined whether this association is influenced by differences among predator species in foraging modes (travel cost, surface feeder or diver) or whether the predator species is a central place forager or not. We examined distributions of two seabird species during their nesting period, the surface-feeding black-legged kittiwake (Rissa tridactyla) and the pursuit-diving thick-billed murre (Uria lomvia), and two baleen whale species, the humpback whale (Megaptera novaeangliae) and the fin whale (Balaenoptera physalus), in relation to two key prey, age-1 walleye pollock (Theragra chalcogramma) and euphausiids (Euphausiidae). Prey surveys were conducted once each year during 2004 and 2006-2010. Concurrent predator surveys were conducted in 2006-2010 (seabirds) and 2008 and 2010 (whales). We compared the seabird and whale foraging locations to where age-1 pollock and euphausiids were concentrated and considered the persistence of these concentrations, where the time-scale of persistence is year (i.e., a comparison among surveys that are conducted once each year). Euphausiids were widespread and concentrations often were reliably found within specific 37 km×37 km blocks ('persistent hot spots of prey'). In contrast, age-1 pollock were more concentrated and their hot spots were persistent only on coarser scales (>37 km). Both seabird species, regardless of foraging mode, were associated with age-1 pollock but not with euphausiids, even though age-1 pollock were less persistent than euphausiids. The higher travel cost central place foragers, thick-billed murres, foraged at prey concentrations nearer their island colonies than black-legged kittiwakes, which were more widespread foragers. Humpback whales were not tied to a central place and mostly were located only where euphausiids were concentrated, and further, often in locations where these concentrations were persistent. Fin whales were associated with locations where age-1 pollock were more likely, similar to black-legged kittiwakes and thick-billed murres, but their association with euphausiids was unclear. Our results suggest that a predator's foraging mode and their restrictions during breeding affect their response to prey persistence.

Pore-Water Chemistry and Hydrology in a Spring-Fed River: Implications for Hyporheic Control of Nutrient Cycling and Speleogenesis

NASA Astrophysics Data System (ADS)

Kurz, M. J.; Martin, J. B.; Cohen, M. J.

2010-12-01

Hyporheic exchange is important for nutrient cycling in rivers, but little is known about the magnitude of this process in karst systems or its influence on speleogenesis and the formation of river channels. We use four pore-water depth profiles to assess nutrient and carbonate processing in the hyporheic zone (HZ) of the Ichetucknee River (north-central, Florida). Co-located pairs of stilling wells equipped with conductivity, temperature, depth (CTD) sensors are used to continuously monitor the hydraulic gradients within the HZ to determine flow directions and temporal variability of groundwater exchange. The Ichetucknee River is sourced from six major and numerous small springs which discharge from the karstic Floridan Aquifer. Downstream and diel variations in nitrate concentrations, specific conductivity and calcite saturation state reflect in-stream processing, but hyporheic exchange should also influence the overall dynamics of nutrient and carbonate fluxes in the river. Our depth profiles and stilling wells are located at four sites in a cross-channel transect and extend through unconsolidated sediment to the solid carbonate of the Floridan Aquifer 35-156 cm below the river bed. Decreasing DOC, pH, and DO concentrations and increased DIC are indicative of organic carbon remineralization in the shallow sediments. Increasing alkalinity, Ca concentrations, specific conductivity and decreasing calcite saturation state indicate carbonate dissolution being driven by the decreasing pH. Decreasing nitrate concentrations indicate denitrification and increasing phosphate concentration could be a result of carbonate dissolution or OC remineralization. Most of these changes appear to occur in the upper 60cm of sediment, below which many concentrations return to values observed in the groundwater, suggesting water discharges from the Floridan Aquifer at the base of the sediment. Hydraulic head is higher in the pore waters than the river indicating groundwater then discharges to the river. Initial modeling of the system indicates that flow through the channel sediment moves horizontally and discharges into the river through the incised channel rather than upwards through the most reactive hyporheic sediments. While differences in chemical composition between the pore water and river water suggest the chemically altered pore water could affect chemical composition of the river it remains unclear the relative fractions of ground water and chemically altered pore water that flow into the river. Future work will attempt to quantify the magnitude of these exchanges over a range of hydrologic conditions.

Comparative Risks of Aldehyde Constituents in Cigarette Smoke Using Transient Computational Fluid Dynamics/Physiologically Based Pharmacokinetic Models of the Rat and Human Respiratory Tracts

PubMed Central

Corley, Richard A.; Kabilan, Senthil; Kuprat, Andrew P.; Carson, James P.; Jacob, Richard E.; Minard, Kevin R.; Teeguarden, Justin G.; Timchalk, Charles; Pipavath, Sudhakar; Glenny, Robb; Einstein, Daniel R.

2015-01-01

Computational fluid dynamics (CFD) modeling is well suited for addressing species-specific anatomy and physiology in calculating respiratory tissue exposures to inhaled materials. In this study, we overcame prior CFD model limitations to demonstrate the importance of realistic, transient breathing patterns for predicting site-specific tissue dose. Specifically, extended airway CFD models of the rat and human were coupled with airway region-specific physiologically based pharmacokinetic (PBPK) tissue models to describe the kinetics of 3 reactive constituents of cigarette smoke: acrolein, acetaldehyde and formaldehyde. Simulations of aldehyde no-observed-adverse-effect levels for nasal toxicity in the rat were conducted until breath-by-breath tissue concentration profiles reached steady state. Human oral breathing simulations were conducted using representative aldehyde yields from cigarette smoke, measured puff ventilation profiles and numbers of cigarettes smoked per day. As with prior steady-state CFD/PBPK simulations, the anterior respiratory nasal epithelial tissues received the greatest initial uptake rates for each aldehyde in the rat. However, integrated time- and tissue depth-dependent area under the curve (AUC) concentrations were typically greater in the anterior dorsal olfactory epithelium using the more realistic transient breathing profiles. For human simulations, oral and laryngeal tissues received the highest local tissue dose with greater penetration to pulmonary tissues than predicted in the rat. Based upon lifetime average daily dose comparisons of tissue hot-spot AUCs (top 2.5% of surface area-normalized AUCs in each region) and numbers of cigarettes smoked/day, the order of concern for human exposures was acrolein > formaldehyde > acetaldehyde even though acetaldehyde yields were 10-fold greater than formaldehyde and acrolein. PMID:25858911

Season, molt, and body size influence mercury concentrations in grebes

USGS Publications Warehouse

Hartman, Christopher; Ackerman, Joshua T.; Herzog, Mark; Eagles-Smith, Collin A.

2017-01-01

We studied seasonal and physiological influences on mercury concentrations in western grebes (Aechmophorus occidentalis) and Clark's grebes (A. occidentalis) across 29 lakes and reservoirs in California, USA. Additionally, at three of these lakes, we conducted a time series study, in which we repeatedly sampled grebe blood mercury concentrations during the spring, summer, and early fall. Grebe blood mercury concentrations were higher among males (0.61 ± 0.12 μg/g ww) than females (0.52 ± 0.10 μg/g ww), higher among Clark's grebes (0.58 ± 0.12 μg/g ww) than western grebes (0.51 ± 0.10 μg/g ww), and exhibited a strong seasonal pattern (decreasing by 60% from spring to fall). Grebe blood THg concentrations exhibited a shallow, inverse U-shaped pattern with body size, and was lowest among the smallest and largest grebes. Further, the relationship between grebe blood mercury concentrations and wing primary feather molt exhibited a shallow U-shaped pattern, where mercury concentrations were highest among birds that had not yet begun molting, decreased approximately 24% between pre-molt and late molt, and increased approximately 19% from late molt to post-molt. Because grebes did not begin molting until mid-summer, lower grebe blood mercury concentrations observed in late summer and early fall were consistent with the onset of primary feather molt. However, because sampling date was a much stronger predictor of grebe mercury concentrations than molt, other seasonally changing environmental factors likely played a larger role than molt in the seasonal variation in grebe mercury concentrations. In the time series study, we found that seasonal trends in grebe mercury concentrations were not consistent among lakes, indicating that lake-specific variation in mercury dynamics influence the overall seasonal decline in grebe blood mercury concentrations. These results highlight the importance of accounting for sampling date, as well as ecological processes that may influence mercury concentrations, when developing monitoring programs to assess site-specific exposure risk of mercury to wildlife.

Water-quality assessment of the Sacramento River basin, California : water quality of fixed sites, 1996-1998

USGS Publications Warehouse

Domagalski, Joseph L.; Dileanis, Peter D.

2000-01-01

Water-quality samples were collected from 12 sites in the Sacramento River Basin, Cali-fornia, from February 1996 through April 1998. Field measurements (dissolved oxygen, pH, specific conductance, alkalinity, and water tem-perature) were completed on all samples, and laboratory analyses were done for suspended sediments, nutrients, dissolved and particulate organic carbon, major ions, trace elements, and mercury species. Samples were collected at four types of locations on the Sacramento River?large tributaries to the Sacramento River, agricul-tural drainage canals, an urban stream, and a flood control channel. The samples were collected across a range of flow conditions representative of those sites during the timeframe of the study. The water samples from the Sacramento River indi-cate that specific conductance increases slightly downstream but that the water quality is indicative of dilute water. Water temperature of the Sacramento River increases below Shasta Lake during the spring and summer irrigation season owing to diversion of water out of the river and subsequent lower flow. All 12 sites had generally low concentrations of nutrients, but chlorophyll concentrations were not measured; therefore, the actual consequences of nutrient loading could not be adequately assessed. Concentrations of dis-solved organic carbon in samples from the Sacramento River and the major tributaries were generally low; the formation of trihalomethanes probably does not currently pose a problem when water from the Sacramento River and its major tributaries is chlorinated for drinking-water purposes. However, dissolved organic carbon concentrations were higher in the urban stream and in agricultural drainage canals, but were diluted upon mixing with the Sacramento River. The only trace element that currently poses a water-quality problem in the Sacramento River is mercury. A federal criterion for the protection of aquatic life was exceeded during this study, and floodwater concentrations of mercury were mostly higher than the criterion. Exceedances of water-quality standards happened most frequently during winter when suspended-sediment concen-trations also were elevated. Most mercury is found in association with suspended sediment. The greatest loading or transport of mercury out of the Sacramento River Basin to the San Francisco Bay occurs in the winter and principally follows storm events.

The effect of air dust pollution on semen quality and sperm parameters among infertile men in west of Iran.

PubMed

Najafpour, Ali; Aghaz, Faranak; Roshankhah, Shiva; Bakhtiari, Mitra

2018-06-26

Pollutants during haze and Asian dust storms are transported out of the Asian continent, affecting the regional climate and the hydrological and biogeochemical cycles. Nonetheless, no specific studies evaluated the dust particles influence on semen quality in a specific geographical area. In this article, we investigated the effect of dust particles on semen quality and sperm parameters among infertile men. A descriptive-analytic study was conducted among 850 infertile men between 2011 and 2015 years. Semen quality was assessed according to the WHO 2010 guidelines, including sperm concentration, progressive motility, and morphology. Four-year average dust particle concentrations were estimated at each participant's address using the Air Pollution Monitoring Station affiliated with the Department of Environment of Kermanshah city were gathered. Dust particle levels were highest in the summer months, in Kermanshah province. Our results show that, dust pollution was found to be significantly negatively correlated with sperm morphology and sperm concentration before and after lab-processing, but sperm progressive motility is low sensitive to dust particles. Our findings showed that exposures to dust particle may influence sperm quantity in infertile men, consistent with the knowledge that sperm morphology and concentration are the most sensitive parameters of dust pollution.

Refinement of regression models to estimate real-time concentrations of contaminants in the Menomonee River drainage basin, southeast Wisconsin, 2008-11

USGS Publications Warehouse

Baldwin, Austin K.; Robertson, Dale M.; Saad, David A.; Magruder, Christopher

2013-01-01

In 2008, the U.S. Geological Survey and the Milwaukee Metropolitan Sewerage District initiated a study to develop regression models to estimate real-time concentrations and loads of chloride, suspended solids, phosphorus, and bacteria in streams near Milwaukee, Wisconsin. To collect monitoring data for calibration of models, water-quality sensors and automated samplers were installed at six sites in the Menomonee River drainage basin. The sensors continuously measured four potential explanatory variables: water temperature, specific conductance, dissolved oxygen, and turbidity. Discrete water-quality samples were collected and analyzed for five response variables: chloride, total suspended solids, total phosphorus, Escherichia coli bacteria, and fecal coliform bacteria. Using the first year of data, regression models were developed to continuously estimate the response variables on the basis of the continuously measured explanatory variables. Those models were published in a previous report. In this report, those models are refined using 2 years of additional data, and the relative improvement in model predictability is discussed. In addition, a set of regression models is presented for a new site in the Menomonee River Basin, Underwood Creek at Wauwatosa. The refined models use the same explanatory variables as the original models. The chloride models all used specific conductance as the explanatory variable, except for the model for the Little Menomonee River near Freistadt, which used both specific conductance and turbidity. Total suspended solids and total phosphorus models used turbidity as the only explanatory variable, and bacteria models used water temperature and turbidity as explanatory variables. An analysis of covariance (ANCOVA), used to compare the coefficients in the original models to those in the refined models calibrated using all of the data, showed that only 3 of the 25 original models changed significantly. Root-mean-squared errors (RMSEs) calculated for both the original and refined models using the entire dataset showed a median improvement in RMSE of 2.1 percent, with a range of 0.0–13.9 percent. Therefore most of the original models did almost as well at estimating concentrations during the validation period (October 2009–September 2011) as the refined models, which were calibrated using those data. Application of these refined models can produce continuously estimated concentrations of chloride, total suspended solids, total phosphorus, E. coli bacteria, and fecal coliform bacteria that may assist managers in quantifying the effects of land-use changes and improvement projects, establish total maximum daily loads, and enable better informed decision making in the future.

Toward Developing a New Occupational Exposure Metric Approach for Characterization of Diesel Aerosols

PubMed Central

Cauda, Emanuele G.; Ku, Bon Ki; Miller, Arthur L.; Barone, Teresa L.

2015-01-01

The extensive use of diesel-powered equipment in mines makes the exposure to diesel aerosols a serious occupational issue. The exposure metric currently used in U.S. underground noncoal mines is based on the measurement of total carbon (TC) and elemental carbon (EC) mass concentration in the air. Recent toxicological evidence suggests that the measurement of mass concentration is not sufficient to correlate ultrafine aerosol exposure with health effects. This urges the evaluation of alternative measurements. In this study, the current exposure metric and two additional metrics, the surface area and the total number concentration, were evaluated by conducting simultaneous measurements of diesel ultrafine aerosols in a laboratory setting. The results showed that the surface area and total number concentration of the particles per unit of mass varied substantially with the engine operating condition. The specific surface area (SSA) and specific number concentration (SNC) normalized with TC varied two and five times, respectively. This implies that miners, whose exposure is measured only as TC, might be exposed to an unknown variable number concentration of diesel particles and commensurate particle surface area. Taken separately, mass, surface area, and number concentration did not completely characterize the aerosols. A comprehensive assessment of diesel aerosol exposure should include all of these elements, but the use of laboratory instruments in underground mines is generally impracticable. The article proposes a new approach to solve this problem. Using SSA and SNC calculated from field-type measurements, the evaluation of additional physical properties can be obtained by using the proposed approach. PMID:26361400

Clinical Pharmacology Quality Assurance (CPQA) Program: Models for Longitudinal Analysis of Antiretroviral (ARV) Proficiency Testing for International Laboratories

PubMed Central

DiFrancesco, Robin; Rosenkranz, Susan L.; Taylor, Charlene R.; Pande, Poonam G.; Siminski, Suzanne M.; Jenny, Richard W.; Morse, Gene D.

2013-01-01

Among National Institutes of Health (NIH) HIV Research Networks conducting multicenter trials, samples from protocols that span several years are analyzed at multiple clinical pharmacology laboratories (CPLs) for multiple antiretrovirals (ARV). Drug assay data are, in turn, entered into study-specific datasets that are used for pharmacokinetic analyses, merged to conduct cross-protocol pharmacokinetic analysis and integrated with pharmacogenomics research to investigate pharmacokinetic-pharmacogenetic associations. The CPLs participate in a semi-annual proficiency testing (PT) program implemented by the Clinical Pharmacology Quality Assurance (CPQA) program. Using results from multiple PT rounds, longitudinal analyses of recovery are reflective of accuracy and precision within/across laboratories. The objectives of this longitudinal analysis of PT across multiple CPLs were to develop and test statistical models that longitudinally: (1)assess the precision and accuracy of concentrations reported by individual CPLs; (2)determine factors associated with round-specific and long-term assay accuracy, precision and bias using a new regression model. A measure of absolute recovery is explored as a simultaneous measure of accuracy and precision. Overall, the analysis outcomes assured 97% accuracy (±20% of the final target concentration of all (21)drug concentration results reported for clinical trial samples by multiple CPLs).Using the CLIA acceptance of meeting criteria for ≥2/3 consecutive rounds, all ten laboratories that participated in three or more rounds per analyte maintained CLIA proficiency. Significant associations were present between magnitude of error and CPL (Kruskal Wallis [KW]p<0.001), and ARV (KW p<0.001). PMID:24052065

Clinical pharmacology quality assurance program: models for longitudinal analysis of antiretroviral proficiency testing for international laboratories.

PubMed

DiFrancesco, Robin; Rosenkranz, Susan L; Taylor, Charlene R; Pande, Poonam G; Siminski, Suzanne M; Jenny, Richard W; Morse, Gene D

2013-10-01

Among National Institutes of Health HIV Research Networks conducting multicenter trials, samples from protocols that span several years are analyzed at multiple clinical pharmacology laboratories (CPLs) for multiple antiretrovirals. Drug assay data are, in turn, entered into study-specific data sets that are used for pharmacokinetic analyses, merged to conduct cross-protocol pharmacokinetic analysis, and integrated with pharmacogenomics research to investigate pharmacokinetic-pharmacogenetic associations. The CPLs participate in a semiannual proficiency testing (PT) program implemented by the Clinical Pharmacology Quality Assurance program. Using results from multiple PT rounds, longitudinal analyses of recovery are reflective of accuracy and precision within/across laboratories. The objectives of this longitudinal analysis of PT across multiple CPLs were to develop and test statistical models that longitudinally: (1) assess the precision and accuracy of concentrations reported by individual CPLs and (2) determine factors associated with round-specific and long-term assay accuracy, precision, and bias using a new regression model. A measure of absolute recovery is explored as a simultaneous measure of accuracy and precision. Overall, the analysis outcomes assured 97% accuracy (±20% of the final target concentration of all (21) drug concentration results reported for clinical trial samples by multiple CPLs). Using the Clinical Laboratory Improvement Act acceptance of meeting criteria for ≥2/3 consecutive rounds, all 10 laboratories that participated in 3 or more rounds per analyte maintained Clinical Laboratory Improvement Act proficiency. Significant associations were present between magnitude of error and CPL (Kruskal-Wallis P < 0.001) and antiretroviral (Kruskal-Wallis P < 0.001).

Water chemistry near the closed Norman Landfill, Cleveland County, Oklahoma 1995

USGS Publications Warehouse

Schlottmann, Jamie L.

2001-01-01

The Norman Landfill was selected for study as part of the U.S. Geological Survey Toxic Substances Hydrology Program in 1994. The landfill is located south of the City of Norman on alluvial deposits of the Canadian River. Type of waste deposited in the landfill from 1922 to 1973 was largely unrestricted and may include substances now recognized as hazardous. Dissolved and suspended substances leached from wastes in the closed and capped landfill are now in ground water extending toward the Canadian River as a plume of leachate. Water samples were collected from two stock wells, one domestic well, temporary drive-point wells, the Canadian River, and a small intermittent stream hydraulically downgradient of the capped landfill known as the slough. Most constituent concentrations were greater in ground water downgradient from the capped landfill than in background ground water and were greater in the slough than in the Canadian River. Concentrations of most constituents in the Canadian River, other than sulfate, manganese, and iron, were similar to concentrations in background ground water. Some constituents measured in ground-water for this investigation are potential indicators of leachate contamination. Potential indicators that could be used to differentiate leachate contaminated water from uncontaminated ground water of the alluvial aquifer include specific conductance, chloride, alkalinity, dissolved organic carbon, boron, and dD. Specific conductance and chloride were greater in water from wells downgradient of the landfill than water from background wells. Dissolved organic carbon and boron also were greater in the leachate contaminated ground water than in background ground water.

Water-quality variations in Antelope Creek and Deadmans Run, Lincoln, Nebraska

USGS Publications Warehouse

Pettijohn, R.A.; Engberg, R.A.

1985-01-01

Eleven sets of samples from five sites on Antelope Creek and Dead Man 's Run in Lincoln, Nebraska, were collected from December 1982 through June 1983 to study water-quality variations. Specific-conductance values generally were similar for Antelope Creek at 52nd Street and 27th Street, but during a low-flow survey of December 1 they increased from 974 to 8,700 microsiemens per centimeter at 25 C from 27th Street to Court Street. Seepage of saline water from underlying bedrock to the stream occurs in this reach. Specific-conductance values were less variable for Dead Man 's Run, increasing an average of only 47 percent from 66th Street to U.S. Highway 6. Specific-conductance values were less at high flows in Antelope Creek, except in samples collected on January 6, 1983, which contained runoff from salted streets. Sodium and chloride concentrations in these samples were from 5 to 10 times greater than those measured in any other samples. Stray-current corrosion occurs when current flows between dissimilar metals. Zinc-coated wire of channel-stabilization structures (gabions) may be an anode and material within the stream banks may be a cathode. Dissolution of the zinc coating by this type of corrosion may be a cause for gabion deterioration in both streams. (USGS)

Surface- and Ground-Water Monitoring and Mapping of Selected Features at the Blue Ridge Parkway Mt. Pisgah Campground, Haywood County, North Carolina, 2002

USGS Publications Warehouse

Smith, Douglas G.

2004-01-01

During 2002, a baseline study of hydrologic conditions was conducted, and selected features were mapped within the Mt. Pisgah campground on the Blue Ridge Parkway in Haywood County, North Carolina. Field surveys were performed by using global positioning system equipment one time (January 2002) during the study to locate hydrologic and other types of features in the study area. Water-level and streamflow data and seasonal water-quality samples were collected from a stream that receives all surface-water drainage from the campground area. During 2002, water levels (stage) in the stream ranged from 1.09 to 1.89 feet above gage datum (4,838.06 to 4,838.86 feet above mean sea level). Flow in the stream ranged from 0.05 to 9.7 cubic feet per second. Annual daily mean flow for calendar year 2002 was approximately 0.35 cubic foot per second (about 226,000 gallons per day). Samples collected from the stream had low concentrations of all constituents measured. Four compounds associated with human activity (camphor, N,N-diethyl-meta-toluamide (the insect repellent DEET), tributylphosphate, and methylsalicylate) were detected in the stream samples; however, concentrations were less than detection levels. Stream samples collected in April and September and analyzed for fecal coliform bacteria had densities of 76 and 110 colonies per 100 milliliters of water, respectively. No violations of water-quality standards were noted for any constituent measured in the stream samples. Seven shallow ground-water wells were installed near a natural area in the center of the campground. Ground-water levels measured periodically in these wells and in two existing shallow piezometers generally were highest in the spring and lowest in the fall. Water temperature, pH, and specific conductance were measured in samples collected from the shallow wells in April and September 2002. Measured pH values were consistently lowest in samples from two wells on the west side of the natural area and highest in samples from the well located near the center of the natural area. Specific-conductance values measured in samples from wells on the east side of the natural area were lower than those measured in samples from the other wells. Specific-conductance values measured in samples from two wells on the west side and from one well near the center of the natural area generally were two to three times higher than the specific-conductance values measured in samples from wells on the east side of the natural area. Samples for fecal coliform bacteria were collected from six wells on September 11, 2002. The fecal coliform densities in samples from most of the wells were less than or equal to 8 colonies per 100 milliliters. Samples from two of the three wells on the west side of the natural area had coliform densities of 16 and 480 colonies per 100 milliliters. Other ground-water samples collected on September 11 and September 24 were analyzed with a spectrophotometer in the U.S. Geological Survey (USGS) North Carolina District Office for nitrate concentrations only. From the samples collected on September 11, estimated nitrate concentrations of 1 milligram per liter or less were detected in three wells, two on the west side and one on the east side of the natural area. Nitrate was not detected with a spectrophotometer in any of the ground-water samples collected on September 24. Indicator test strips also were used in the field to screen for nitrate and nitrite in ground-water samples collected on September 24. Nitrate was detected by test strips in one well on the west side of the natural area, with estimated concentrations of 1 milligram per liter or less indicated. Nitrite was not detected by the test strips in samples collected from any of the wells.

[Sensitivity and specificity of prick skin test with two concentrations of standardized extract of Culex quinquefasciatus in allergic children].

PubMed

Castro-Almarales, Raúl Lázaro; Álvarez-Castelló, Mirta; Ronquillo-Díaz, Mercedes; Rodríguez-Canosa, José S; González-León, Mayda; Navarro-Viltre, Bárbara I; Betancourt-Mesia, Daniel; Enríquez-Domínguez, Irene; Reyes-Zamora, Mary Carmen; Oliva-Díaz, Yunia; Mateo-Morejón, Maytee; Labrada-Rosado, Alexis

2016-01-01

Diagnostic options for immune reactions to mosquito bites are limited. In Cuba, IgE-mediated reactions are frequently related to Culex quinquefasciatus bite. To determine the sensitivity and specificity of skin prick test with two doses of standardized extract in nitrogen protein units (PNU of Culex quinquefasciatus (BIOCEN, Cuba). An analytical study was conducted on 100 children between 2 and 15 years old. Fifty atopic patients with a history of allergy to mosquito bite and positive specific serum IgE Culex quinquefasciatus and fifty atopic patients without a history of allergy to mosquito bite and negative specific serum IgE to Culex quinquefasciatus. Skin prick tests (SPT) were performed by duplicates on the forearms of the patients. Investigated doses were 100 PNU/mL and 10 PNU/mL. SPT with the highest concentration obtained a mean wheal size of 22.09 mm2 and for lower doses of 8.09 mm2, a statistically significant difference (p=0.001, Student's t test). Positive skin test correlated in 100% of patients with the presence of specific IgE. Testing with both doses showed a 94% of specificity and 88% of sensitivity. The diagnostic accuracy of SPT using both doses of standardized extract was similar, which justifies its use for diagnosis of sensitization to Culex quinquefasciatus in patients with symptoms of allergy to mosquito bite.

Feasibility Studies on Pipeline Disposal of Concentrated Copper Tailings Slurry for Waste Minimization

NASA Astrophysics Data System (ADS)

Senapati, Pradipta Kumar; Mishra, Barada Kanta

2017-06-01

The conventional lean phase copper tailings slurry disposal systems create pollution all around the disposal area through seepage and flooding of waste slurry water. In order to reduce water consumption and minimize pollution, the pipeline disposal of these waste slurries at high solids concentrations may be considered as a viable option. The paper presents the rheological and pipeline flow characteristics of copper tailings samples in the solids concentration range of 65-72 % by weight. The tailings slurry indicated non-Newtonian behaviour at these solids concentrations and the rheological data were best fitted by Bingham plastic model. The influence of solids concentration on yield stress and plastic viscosity for the copper tailings samples were discussed. Using a high concentration test loop, pipeline experiments were conducted in a 50 mm nominal bore (NB) pipe by varying the pipe flow velocity from 1.5 to 3.5 m/s. A non-Newtonian Bingham plastic pressure drop model predicted the experimental data reasonably well for the concentrated tailings slurry. The pressure drop model was used for higher size pipes and the operating conditions for pipeline disposal of concentrated copper tailings slurry in a 200 mm NB pipe with respect to specific power consumption were discussed.

Altitudinal and chiral signature of persistent organochlorine pesticides in air, soil, and spruce needles (Picea abies) of the Alps.

PubMed

Shen, Heqing; Henkelmann, Bernhard; Levy, Walkiria; Zsolnay, Adam; Weiss, Peter; Jakobi, Gert; Kirchner, Manfred; Moche, Wolfgang; Braun, Katharina; Schramm, Karl-Werner

2009-04-01

The present study investigated the distribution, transportation, and biodegradation of the selected chiral persistent organochlorine pesticides (OCP) in the Alps. In the complex environment, we found the movement and fate of OCP could be defined by many factors. Taking HCE as an example, below the timberline its accumulation from air into SPMD increased with altitude and seasonally changed, but the trends reversed above the timberline. In soil, the tendency of HCE concentrations vs organic materials followed a sigmoid curve, and HCE concentration-altitude correlations are positive in central Alps but negative in southern Alps. The HCE enantiomeric ratios (ERs) in soil correlated to HCE isomers concentrations, the humus pH values, and the sampling site altitudes. HCE shift from humus to mineral soil can also be traced by ERs. The altitudinal and longitudinal trends in needles suggested that alpha-HCH has a more complex movementthan HCE in Alps. In conclusion, altitude conducted condensation, plant canopies, organic material in soil, and geographic specific precipitations may affect OCP distributions and transportation, whereas altitude conducted temperature and soil pH could dictate their fate in the environment.

Dielectric elastomers with novel highly-conducting electrodes

NASA Astrophysics Data System (ADS)

Böse, Holger; Uhl, Detlev

2013-04-01

Beside the characteristics of the elastomer material itself, the performance of dielectric elastomers in actuator, sensor as well as generator applications depends also on the properties of the electrode material. Various electrode materials based on metallic particles dispersed in a silicone matrix were manufactured and investigated. Anisotropic particles such as silver-coated copper flakes and silver-coated glass flakes were used for the preparation of the electrodes. The concentration of the metallic particles and the thickness of the electrode layers were varied. Specific conductivities derived from resistance measurements reached about 100 S/cm and surmount those of the reference materials based on graphite and carbon black by up to three orders of magnitude. The high conductivities of the new electrode materials can be maintained even at very large stretch deformations up to 200 %.

Physical and chemical properties of water and sediments, Grand Portage and Wauswaugoning Bays, Lake Superior, Grand Portage Indian Reservation, northeastern Minnesota, 1993-96

USGS Publications Warehouse

Ruhl, J.F.

1997-01-01

This report is a compilation of data on the physical and chemical properties of water and sediments in Grand Portage and Wauswaugoning Bays of Lake Superior along the shoreline of the Grand Portage Indian Reservation. The data were collected during 1993-96 by the U.S. Geological Survey in cooperation with the Grand Portage Indian Reservation. The data include: (1) temperature, pH, and specific conductance measurements and dissolved oxygen concentrations; (2) Secchi disk transparency, alkalinity, and turbidity measurements; (3) fecal Coliform and fecal Streptococcal bacteria colony counts (per 100 milliliters of sample water); (4) major and minor ion, nutrient, and trace-metal concentrations; (5) dissolved and suspended residue concentrations; (6) pesticide, phenol, and asbestos concentrations; (7) suspended sediment trace-metal concentrations; and (8) bottom sediment trace-metal concentrations. Water samples were collected from nine sites; suspended and bottom sediment samples were collected from five sites. The data in this report can be used to evaluate present water-quality conditions and as a reference to monitor potential long-term changes in these conditions.

Water-quality assessment of part of the Upper Mississippi River Basin, Minnesota and Wisconsin - Ground-water quality in three different land-use areas, 1996-98

USGS Publications Warehouse

Fong, Alison L.

2000-01-01

Comparisons of previous land-use studies in Minnesota with the three NAWQA land-use studies generally indicated the same patterns. Ground-water quality in surficial sand and gravel aquifers is affected by land-use practices. Ground water in urban studies has greater specific conductances, alkalinities, chloride, sodium, sulfate, and dissolved solid concentrations than agricultural or forested/undeveloped studies. Nitrate-nitrogen was detected in greater concentrations in agricultural studies than in urban studies, with concentrations in the forested/undeveloped studies less than in the agricultural or the urban studies. Agricultural studies have the greatest detection rates, numbers, and total concentrations of pesticides. Pesticide detection rates and total pesticide concentrations in the urban studies were less than in the agricultural studies, with the most frequently detected pesticides (prometon and dicamba) different than those in the agricultural studies (atrazine and deethylatrazine). A greater number of VOCs were detected in urban studies and at greater concentrations than in agricultural studies. Few pesticides or VOCs were detected in forested/undeveloped studies.

Saturation of conductance in single ion channels: the blocking effect of the near reaction field.

PubMed

Nadler, Boaz; Schuss, Zeev; Hollerbach, Uwe; Eisenberg, R S

2004-11-01

The ionic current flowing through a protein channel in the membrane of a biological cell depends on the concentration of the permeant ion, as well as on many other variables. As the concentration increases, the rate of arrival of bath ions to the channel's entrance increases, and typically so does the net current. This concentration dependence is part of traditional diffusion and rate models that predict Michaelis-Menten current-concentration relations for a single ion channel. Such models, however, neglect other effects of bath concentrations on the net current. The net current depends not only on the entrance rate of ions into the channel, but also on forces acting on ions inside the channel. These forces, in turn, depend not only on the applied potential and charge distribution of the channel, but also on the long-range Coulombic interactions with the surrounding bath ions. In this paper, we study the effects of bath concentrations on the average force on an ion in a single ion channel. We show that the force of the reaction field on a discrete ion inside a channel embedded in an uncharged lipid membrane contains a blocking (shielding) term that is proportional to the square root of the ionic bath concentration. We then show that different blocking strengths yield different behavior of the current-concentration and conductance-concentration curves. Our theory shows that at low concentrations, when the blocking force is weak, conductance grows linearly with concentration, as in traditional models, e.g., Michaelis-Menten formulations. As the concentration increases to a range of moderate shielding, conductance grows as the square root of concentration, whereas at high concentrations, with high shielding, conductance may actually decrease with increasing concentrations: the conductance-concentration curve can invert. Therefore, electrostatic interactions between bath ions and the single ion inside the channel can explain the different regimes of conductance-concentration relations observed in experiments.

External quality-assurance results for the National Atmospheric Deposition Program/National Trends Network, 1997-99

USGS Publications Warehouse

Gordon, John D.; Latysh, Natalie E.; Lindholm, Sandy J.

2003-01-01

Five external quality-assurance programs were operated by the U.S. Geological Survey for the National Atmospheric Deposition Program/ National Trends Network (NADP/NTN) during 1997 through 1999: the intersite-comparison program, the blind-audit program, the field- audit program, the interlaboratory-comparison program, and the collocated-sampler program. The intersite-comparison program assesses the accuracy of pH and specific-conductance determinations made by NADP/NTN site operators. In two 1997 intersite-comparison studies, 83.7 and 85.8 percent of the pH determinations met the NADP/NTN accuracy goals, whereas 97.3 and 92.4 percent of the specific-conductance determinations met the NADP/NTN accuracy goals. The percentage of pH and specific-conductance determinations that met the accuracy goals in 1998 were, for the most part, higher than in 1997. In two 1998 studies, 90.9 and 90.3 percent of the pH determinations met the accuracy goals compared to 94.7 and 96.0 percent of the specific- conductance measurements meeting the accuracy goals. In one 1999 intersite-comparison study, 89.5 percent and 99.4 percent of pH and specific- conductance determinations, respectively, met the NADP/NTN accuracy goals. The blind-audit program evaluates the effects of routine sample handling, processing, and shipping on the analytical bias and precision of weekly precipitation samples. A portion of the blind-audit sample subject to the normal onsite handling and processing of a weekly precipitation sample is referred to as the bucket portion, whereas the portion receiving only minimal handling is referred to as the bottle portion. Positive bias in regard to blind-audit results indicates that the bucket portion has a higher concentration than the bottle portion. The paired t-test for the 1997 through 1999 blind- audit data indicates that routine sample handling, processing, and shipping introduced a positive bias (a=0.05) for calcium and chloride and a negative bias (cz=0.05) for hydrogen ion. During 1997 through 1999, the median paired differences between the bucket and bottle portions ranged from 0.00 milligram per liter for nitrate and ammonium to +0.010 milligram per liter for both chloride and sulfate. The median paired difference between the bucket and bottle portions for hydrogen ion was -1.086 microequivalents per liter, whereas for specific conductance, the median paired difference between the bucket and bottle portions was -0.200 microsiemen per centimeter during 1997 through 1999. Surface-chemistry effects due to variable amounts of precipitation contacting prewashed sample-collection and shipping-container surfaces were studied in the blind-audit program by using three different sample volumes. The sample- collection and shipping containers used for the blind-audit study were obtained from the site operator's supply and could have been used for precipitation samples. Results of a Kruskal-Wallis analysis of variance test of the relation between paired blind-audit sample differences in units of concentration and sample volume were statistically significant for magnesium, chloride, sulfate, and hydrogen ion during 1997 through 1999. Before 1994, at least 5 of the 10 analytes displayed a statistically significant difference between paired blind-audit differences in units of concentration and sample volume, supporting the premise that chemical reactions between the 13-liter bucket shipping container (primarily the butadiene o-ring lid of the shipping container) and the sample, which resulted in an increasing loss of hydrogen ion with increasing volume, have been eliminated by the new l-liter bottle sample- shipping protocol. The field-audit program measures the effects of field exposure, handling, and processing on the chemistry of NADP/NTN precipitation samples. In the field-audit program, the site operator is instructed to process and submit a quality- control sample following a standard 7-day, Tuesday-to-Tuesday sampling period with no

Does short-term potassium fertilization improve recovery from drought stress in laurel?

PubMed

Oddo, Elisabetta; Inzerillo, Simone; Grisafi, Francesca; Sajeva, Maurizio; Salleo, Sebastiano; Nardini, Andrea

2014-08-01

Xylem hydraulic conductance varies in response to changes in sap solute content, and in particular of potassium (K(+)) ion concentration. This phenomenon, known as the 'ionic effect', is enhanced in embolized stems, where it can compensate for cavitation-induced loss of hydraulic conductance. Previous studies have shown that in well-watered laurel plants (Laurus nobilis L.), potassium concentration of the xylem sap and plant hydraulic conductance increased 24 h after fertilization with KCl. The aim of this work was to test whether water-stressed laurel plants, grown under low potassium availability, could recover earlier from stress when irrigated with a KCl solution instead of potassium-free water. Two-year-old potted laurel seedlings were subjected to water stress by suspending irrigation until leaf conductance to water vapour (g(L)) dropped to ∼30% of its initial value and leaf water potential (ψ(L)) reached the turgor loss point (ψ(TLP)). Plants were then irrigated either with water or with 25 mM KCl and monitored for water status, gas exchange and plant hydraulics recovery at 3, 6 and 24 h after irrigation. No significant differences were found between the two experimental groups in terms of ψ(L), g(L), plant transpiration, plant hydraulic conductance or leaf-specific shoot hydraulic conductivity. Analysis of xylem sap potassium concentration showed that there were no significant differences between treatments, and potassium levels were similar to those of potassium-starved but well-watered plants. In conclusion, potassium uptake from the soil solution and/or potassium release to the xylem appeared to be impaired in water-stressed plants, at least up to 24 h after relief from water stress, so that fertilization after the onset of stress did not result in any short-term advantage for recovery from drought. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Data Validation Package May 2015, Groundwater Sampling at the Shoal, Nevada, Site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Findlay, Rick; Kautsky, Mark

The U.S. Department of Energy Office of Legacy Management conducted annual sampling at the Shoal, Nevada, Site (Shoal) in May 2015. Groundwater samples were collected from wells MV-1, MV-2, MV-3, MV-4, MV-5, H-3, HC-1, HC-2d, HC-3, HC-4, HC-5, HC-6, HC-7, HC-8, and HS-1. Sampling was conducted as specified in the Sampling and Analysis Plan for US. Department of Energy Office of Legacy Management Sites (LMS/PRO/S04351, continually updated, http://energy.gov/lm/downloads/sampling-and-analysis-plan-us-department-energy­ office-legacy-management-sites). Monitoring wells MV-1, MV-2, MV-3, MV-4, MV-5, HC-2d, HC-4, HC-5, HC-7, HC-8, and HS-1 were purged prior to sampling using dedicated submersible pumps. At least one well casing volume was removed,more » and field parameters (temperature, pH, and specific conductance) were allowed to stabilize before samples were collected. Samples were collected from wells H-3, HC-1, HC-3, and HC-6 using a depth-specific bailer because these wells are not completed with dedicated submersible pumps. Samples were submitted under Requisition Index Number (RIN) 15057042 to ALS Laboratory Group in Fort Collins, Colorado, for the determination of bromide, gross alpha, gross beta, tritium, uranium isotopes, and total uranium (by mass); and under RIN 15057043 to the University of Arizona for the determination of carbon-14 and iodine-129. A duplicate sample from location MV-2 was included with RIN 15057042. The laboratory results from the 2015 sampling event are consistent with those of previous years with the exception of sample results from well HC-4. This well continues to be the only well with tritium concentrations above the laboratory’s minimum detectable concentration which is attributed to the wells proximity to the nuclear detonation. The tritium concentration (731 picocuries per liter [pCi/L]) is consistent with past results and is below the U.S. Environmental Protection Agency's (EPA) maximum contaminant level (MCL) of 20,000 pCi/L. However, concentrations of gross alpha, uranium, and carbon-14 all increased in the sample from well HC-4 during this sampling event. Concentrations of gross alpha and uranium have been above the EPA MCLs in this well since 2012 and the highest concentrations of gross alpha (60.6 pCi/L) and uranium (110 micrograms per liter) were detected during this sampling event. Refer to the time-concentration plots included with this report. Also see the 2015 Groundwater Monitoring Report Project Shoal Area: Subsurface Corrective Action Unit 447 for additional information on the 2015 sampling results.« less

Evaluation and trends of land cover, streamflow, and water quality in the North Canadian River Basin near Oklahoma City, Oklahoma, 1968–2009

USGS Publications Warehouse

Esralew, Rachel A.; Andrews, William J.; Smith, S. Jerrod

2011-01-01

The U.S. Geological Survey, in cooperation with the city of Oklahoma City, collected water-quality samples from the North Canadian River at the streamflow-gaging station near Harrah, Oklahoma (Harrah station), since 1968, and at an upstream streamflow-gaging station at Britton Road at Oklahoma City, Oklahoma (Britton Road station), since 1988. Statistical summaries and frequencies of detection of water-quality constituent data from water samples, and summaries of water-quality constituent data from continuous water-quality monitors are described from the start of monitoring at those stations through 2009. Differences in concentrations between stations and time trends for selected constituents were evaluated to determine the effects of: (1) wastewater effluent discharges, (2) changes in land-cover, (3) changes in streamflow, (4) increases in urban development, and (5) other anthropogenic sources of contamination on water quality in the North Canadian River downstream from Oklahoma City. Land-cover changes between 1992 and 2001 in the basin between the Harrah station and Lake Overholser upstream included an increase in developed/barren land-cover and a decrease in pasture/hay land cover. There were no significant trends in median and greater streamflows at either streamflow-gaging station, but there were significant downward trends in lesser streamflows, especially after 1999, which may have been associated with decreases in precipitation between 1999 and 2009 or construction of low-water dams on the river upstream from Oklahoma City in 1999. Concentrations of dissolved chloride, lead, cadmium, and chlordane most frequently exceeded the Criterion Continuous Concentration (a water-quality standard for protection of aquatic life) in water-quality samples collected at both streamflow-gaging stations. Visual trends in annual frequencies of detection were investigated for selected pesticides with frequencies of detection greater than 10 percent in all water samples collected at both streamflow-gaging stations. Annual frequencies of detection of 2,4-dichlorophenoxyacetic acid and bromacil increased with time. Annual frequencies of detection of atrazine, chlorpyrifos, diazinon, dichlorprop, and lindane decreased with time. Dissolved nitrogen and phosphorus concentrations were significantly greater in water samples collected at the Harrah station than at the Britton Road station, whereas specific conductance was greater at the Britton Road station. Concentrations of dissolved oxygen, biochemical oxygen demand, and fecal coliform bacteria were not significantly different between stations. Daily minimum, mean, and maximum specific conductance collected from continuous water-quality monitors were significantly greater at the Britton Road station than in water samples collected at the Harrah station. Daily minimum, maximum, and diurnal fluctuations of water temperature collected from continuous water-quality monitors were significantly greater at the Harrah station than at the Britton Road station. The daily maximums and diurnal range of dissolved oxygen concentrations were significantly greater in water samples collected at the Britton Road station than at the Harrah station, but daily mean dissolved oxygen concentrations in water at those streamflow-gaging stations were not significantly different. Daily mean and diurnal water temperature ranges increased with time at the Britton Road and Harrah streamflow-gaging stations, whereas daily mean and diurnal specific conductance ranges decreased with time at both streamflow-gaging stations from 1988–2009. Daily minimum dissolved oxygen concentrations collected from continuous water-quality monitors more frequently indicated hypoxic conditions at the Harrah station than at the Britton Road station after 1999. Fecal coliform bacteria counts in water decreased slightly from 1988–2009 at the Britton Road station. The Seasonal Kendall's tau test indicated significant downward trends in

Effect of Drought on Streamflow and Stream-Water Quality in Colorado, July through September 2002

USGS Publications Warehouse

Chafin, Daniel T.; Druliner, A. Douglas

2007-01-01

During 2002, Colorado experienced the State's worst drought since 1977. In 2003, the U.S. Geological Survey entered into cooperative agreement with the Colorado Department of Public Health and Environment to evaluate the general effects of drought on the water quality of streams in Colorado during summer 2002 by analyzing a water-quality data set obtained during summer 2002 in cooperation with a variety of State and local governments. Water samples were collected at 148 stream sites in Colorado and were measured or analyzed for field properties, major ions, nutrients, organic carbon, bacteria, and dissolved and total recoverable metals. Mean annual streamflow was analyzed at 134 sites in Colorado, and mean summer (July-September) streamflow for 2002 was determined for 146 sites for water years 1978-2002. Mean annual streamflow for 2002 had an average percentile of 29.4 and mean summer streamflow for 2002 had an average percentile of 7.6 relative to 1978-2002. These results indicate that streamflow in Colorado was substantially less than median streamflow for the period and that the effect of drought on streamflow was greater during summer 2002 than during water year 2002 (October 1, 2001, through September 30, 2002). Few measured constituent concentrations or values were elevated or depressed on a widespread basis during summer 2002. Specific conductance was elevated (in the upper quartile relative to historical data) in five of the seven basins that had sufficient data for characterization, indicating that specific conductance likely was affected by drought in those basins. Chloride concentrations were elevated in three of five basins with sufficient data and indicate that chloride concentration generally was affected by drought in those basins. Sulfate concentration was elevated in four of six basins with sufficient data. The widespread elevation of specific conductance and concentrations of chloride and sulfate indicates that salinity generally was affected by drought in Colorado streams during July-September 2002, likely because streamflow at most sites was dominated by base flow of ground water, which usually has substantially greater salinity compared to runoff from precipitation. Total-recoverable iron and manganese concentrations were depressed (in the lower quartile of historical data) in the Arkansas River Basin, which likely was due to reduced land-surface washoff of sediment containing oxyhydroxides of these metals. Of the 246 water samples collected at 148 sites during the summer of 2002, constituents in 115 exceeded Colorado water-quality standards. Constituents that exceeded water-quality standards were pH (all 9.0 standard unit exceedances; 9 samples), chloride (1 sample), sulfate (9 samples), dissolved ammonia (10 samples), dissolved nitrite nitrogen (3 samples), E. coli (Escherichia coli) bacteria (34 samples, 20 in Arkansas River Basin), fecal-coliform bacteria (18 samples, all in Arkansas River Basin), dissolved copper (1 sample), dissolved iron (3 samples), total-recoverable iron (3 samples), dissolved manganese (13 samples), dissolved selenium (10 samples), and dissolved zinc (1 sample). Of these 115 exceedances, historical data were sufficient to conclude that 21 probably were affected by drought, that 39 probably were not affected by drought, and that 55 were of indeterminate nature. Specific conductance indicates that the San Juan River Basin (average percentile 95.2) experienced the greatest effects of drought on water quality during summer 2002 compared to other basins in Colorado, followed by the Upper Colorado (90.0) and Dolores River (85.7) Basins. The South Platte River Basin (70.9) experienced the least effect of drought, and the Yampa and White River Basin group (73.7) had the second smallest effect. The Gunnison River (82.1) and Arkansas River (81.2) Basins had intermediate drought effects. The Rio Grande had insufficient data to rank the relative effect of drought on salinity.

Molecular version of the resistive pulse technique: counting ATP by a single ion channel

NASA Astrophysics Data System (ADS)

Rostovtseva, T. K.; Bezrukov, S. M.

1998-03-01

The ``molecular Coulter counter'' concept has been used to study transport of ATP molecules through the nanometer-scale aqueous pore of the voltage-dependent mitochondrial ion channel, VDAC. We examine the ATP-induced current fluctuations and the change in average current through a single fully open channel reconstituted into a planar lipid bilayer. At high salt concentration (1M NaCl), the addition of ATP reduces both solution specific conductivity and channel conductance, but the effect on the channel is several times stronger and shows saturation behavior at 50 mM ATP concentration. ATP addition also generates an excess noise in the ionic current through the channel. By relating the low-frequency spectral density of the noise to the equilibrium diffusion of ATP molecules in the aqueous pore, we calculate a diffusion coefficient D = (1.6-3.3)x10-11 m^2 /s. We show that the mesoscopic VDAC pore is a Coulter counter with the added features of attraction and diffusion.

Improvement of chemical monitoring of water-chemistry conditions at thermal power stations based on electric conductivity and pH measurements

NASA Astrophysics Data System (ADS)

Larin, A. B.; Larin, B. M.

2016-05-01

The increased requirements to the quality of the water heat conductor for working superhigh (SHP) and supercritical (SCP) pressure power plants and promising units, including combined-cycle gas turbine (CCGT) units and power plants with ultrasupercritical parameters (USCPs), can largely be satisfied through specific electric conductivity and pH measurements for cooled heat conductor samples combined with calculations of ionic equilibria and indirect measurements of several specified and diagnostic parameters. The possibility of calculating the ammonia and chloride concentrations and the total concentration of hardness and sodium cations in the feed water of drum-type boilers and the phosphate and salt contents in boiler water was demonstrated. An equation for evaluating the content of potentially acid substances in the feed water of monotube boilers was suggested. The potential of the developed procedure for evaluating the state of waterchemistry conditions (WCCs) in power plants with CCGT units was shown.

Crustal solute fluxes and transient carbon dioxide drawdown in the Scottbreen Basin, Svalbard in 2002

NASA Astrophysics Data System (ADS)

Krawczyk, Wiesława Ewa; Bartoszewski, Stefan A.

2008-12-01

SummarySolute fluxes and transient carbon dioxide drawdown in a small glacierized basin investigated on Svalbard in 2002 are presented. It was a sample year within a period of significant climate warming in the Arctic. Discharge was recorded in the Scottbreen Basin (10.1 km 2), Bellsund Fjord, between July 8 and September 10, 2002. Specific runoff for this period was 0.784 m, 22% more than the mean for 1986-2001. The runoff for all of 2002 (i.e. the hydrologic year) was estimated by comparison with Bayelva, the only glacial river with longer records on Svalbard. The specific runoff for 2002 was ˜1.228 m, yielding crustal solute fluxes of 69.4 t km -2 yr -1 (25.8 m 3 km -2 yr -1). This rate is the highest chemical denudation rate reported from glacierized basins on Svalbard, and it may be underestimated because higher solute fluxes at the beginning of the melt season were not taken into account. Crustal fluxes in the fall may also have been higher because it is probable that crustal ion concentrations were increasing after recording stopped in September. The cation denudation rate was 1213 ∑ meq + m -2 yr -1 and the mean annual crustal ion concentration derived from it amounted to 981 μeq L -1. Transient CO 2 drawdown in 2002 was 5242 kg C km -2 yr -1. Most of the carbon dioxide was removed in the summer ablation waters, estimated CO 2 drawdown in the fall being only 13% of the total. Comparison with crustal solute fluxes (CSF) computed from specific conductivity in the 1980s and 1990s suggests that earlier fluxes may have been overestimated by around 19%. Comparing earlier data with the 2002 rates may confirm the influence of climate warming on increasing chemical denudation rates. It was also found that a globally derived equation relating specific conductivity to concentrations of dissolved limestone in water gave estimates of the crustal solute fluxes that were only 1.1% less than those obtained via comprehensive chemical analyses of waters and ion partitioning procedures.

Decrease of Population Divergence in Eurasian Perch (Perca fluviatilis) in Browning Waters: Role of Fatty Acids and Foraging Efficiency

PubMed Central

Scharnweber, Kristin; Strandberg, Ursula; Karlsson, Konrad; Eklöv, Peter

2016-01-01

Due to altered biogeochemical processes related to climate change, highly colored dissolved organic carbon (DOC) from terrestrial sources will lead to a water “brownification” in many freshwater systems of the Northern Hemisphere. This will create deteriorated visual conditions that have been found to affect habitat-specific morphological variations in Eurasian perch (Perca fluviatilis) in a previous study. So far, potential drivers and ultimate causes of these findings have not been identified. We conducted a field study to investigate the connection between morphological divergence and polyunsaturated fatty acid (PUFA) composition of perch from six lakes across a gradient of DOC concentration. We expected a decrease in the prevalence of PUFAs, which are important for perch growth and divergence with increasing DOC concentrations, due to the restructuring effects of DOC on aquatic food webs. In general, rate of morphological divergence in perch decreased with increasing DOC concentrations. Proportions of specific PUFAs (22:6n-3, 18:3n-3, 20:5n-3, and 20:4n-6) identified to primarily contribute to overall differences between perch caught in clear and brown-water lakes tended to be connected to overall decline of morphological divergence. However, no overall significant relationship was found, indicating no severe limitation of essential fatty acids for perch inhabiting brown water lakes. We further broaden our approach by conducting a laboratory experiment on foraging efficiency of perch. Therefore, we induced pelagic and littoral phenotypes by differences in habitat-structure and feeding mode and recorded attack rate in a feeding experiment. Generally, fish were less efficient in foraging on littoral prey (Ephemeroptera) when visual conditions were degraded by brown water color. We concluded that browning water may have a strong effect on the forager’s ability to find particular food resources, resulting in the reduced development of evolutionary traits, such as habitat- specific morphological divergence. PMID:27610617

Graphene-enhanced thermal interface materials for heat removal from photovoltaic solar cells

NASA Astrophysics Data System (ADS)

Saadah, M.; Gamalath, D.; Hernandez, E.; Balandin, A. A.

2016-09-01

The increase in the temperature of photovoltaic (PV) solar cells affects negatively their power conversion efficiency and decreases their lifetime. The negative effects are particularly pronounced in concentrator solar cells. Therefore, it is crucial to limit the PV cell temperature by effectively removing the excess heat. Conventional thermal phase change materials (PCMs) and thermal interface materials (TIMs) do not possess the thermal conductivity values sufficient for thermal management of the next generation of PV cells. In this paper, we report the results of investigation of the increased efficiency of PV cells with the use of graphene-enhanced TIMs. Graphene reveals the highest values of the intrinsic thermal conductivity. It was also shown that the thermal conductivity of composites can be increased via utilization of graphene fillers. We prepared TIMs with up to 6% of graphene designed specifically for PV cell application. The solar cells were tested using the solar simulation module. It was found that the drop in the output voltage of the solar panel under two-sun concentrated illumination can be reduced from 19% to 6% when grapheneenhanced TIMs are used. The proposed method can recover up to 75% of the power loss in solar cells.

Accumulated state assessment of the Peace-Athabasca-Slave River system.

PubMed

Dubé, Monique G; Wilson, Julie E

2013-07-01

Effects-based analysis is a fundamental component of watershed cumulative effects assessment. This study conducted an effects-based analysis for the Peace-Athabasca-Slave River System, part of the massive Mackenzie River Basin, encompassing 20% of Canada's total land mass and influenced by cumulative contributions of the W.A.C. Bennett Dam (Peace River) and industrial activities including oil sands mining (Athabasca River). This study assessed seasonal changes in 1) Peace River water quality and quantity before and after dam development, 2) Athabasca River water quality and quantity before and after oil sands developments, 3) tributary inputs from the Peace and Athabasca Rivers to the Slave River, and 4) upstream to downstream differences in water quality in the Slave River. In addition, seasonal benchmarks were calculated for each river based on pre-perturbation post-perturbation data for future cumulative effects assessments. Winter discharge (January-March) from the Peace and Slave Rivers was significantly higher than before dam construction (pre-1967) (p < 0.05), whereas summer peak flows (May-July) were significantly lower than before the dam showing that regulation has significantly altered seasonal flow regimes. During spring freshet and summer high flows, the Peace River strongly influenced the quality of the Slave River, as there were no significant differences in loadings of dissolved N, total P (TP), total organic C (TOC), total As, total Mn, total V, and turbidity and specific conductance between these rivers. In the Athabasca River, TP and specific conductance concentrations increased significantly since before oil sands developments (1967-2010), whereas dissolved N and sulfate have increased after the oil sands developments (1977-2010). Recently, the Athabasca River had significantly higher concentrations of dissolved N, TP, TOC, dissolved sulfate, specific conductance, and total Mn than either the Slave or the Peace Rivers during the winter months. The transboundary nature of the Peace, Athabasca, and Slave River basins has resulted in fragmented monitoring and reporting of the state of these rivers, and a more consistent monitoring framework is recommended. Copyright © 2012 SETAC.

Water-quality data from two agricultural drainage basins in northwestern Indiana and northeastern Illinois: I. Lagrangian and synoptic data, 1999-2002

USGS Publications Warehouse

Antweiler, Ronald C.; Smith, Richard L.; Voytek, Mary A.; Bohlke, John Karl; Richards, Kevin D.

2005-01-01

Methods of data collection and results of analyses are presented for Lagrangian and synoptic water-quality data collected from two agricultural drainages, the Iroquois River in northwestern Indiana and Sugar Creek in northwestern Indiana and northeastern Illinois. During six separate sampling trips, in April, June and September 1999, May 2000, September 2001 and April 2002, 152 discrete water samples were collected to characterize the water chemistry over the course of 2 to 4 days on each of these drainages. Data were collected for nutrients, major inorganic constituents, dissolved organic carbon, trace elements, dissolved gases, total bacterial cell counts, chlorophyll-a concentrations, and suspended sediment concentrations. In addition, field measurements of streamflow, pH, specific conductance, water temperature, and dissolved oxygen concentration were made during all trips except April 1999.

Drinking-water quality and variations in water levels in the fractured crystalline-rock aquifer, west-central Jefferson County, Colorado. Water-resources investigations (interim)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hall, D.C.; Johnson, C.J.

1979-09-01

In parts of the area, water for domestic use obtained from the fractured crystalline-rock aquifer contained excessive concentrations of dissolved fluoride, dissolved nitrite plus nitrate, dissolved solids, dissolved iron, dissolved manganese, dissolved zinc, coliform bacteria, gross alpha radiation, and gross beta radiation. Based on water-quality analyses from 26 wells located in small urbanized areas, water from 21 of the wells contained excessive concentrations of one or more constituents. Local variations in concentrations of 15 chemical constituents, specific conductance, and water temperature were statistically significant. Depths to water in 11 non-pumping wells ranged from 1 to 15 feet annually. Three-year trendsmore » in water-level changes in 6 of the 11 wells indicated a decrease in stored water in the aquifer.« less

Bilayer lipid composition modulates the activity of dermaseptins, polycationic antimicrobial peptides.

PubMed

Duclohier, Hervé

2006-05-01

The primary targets of defense peptides are plasma membranes, and the induced irreversible depolarization is sufficient to exert antimicrobial activity although secondary modes of action might be at work. Channels or pores underlying membrane permeabilization are usually quite large with single-channel conductances two orders of magnitude higher than those exhibited by physiological channels involved, e.g., in excitability. Accordingly, the ion specificity and selectivity are quite low. Whereas, e.g., peptaibols favor cation transport, polycationic or basic peptides tend to form anion-specific pores. With dermaseptin B2, a 33 residue long and mostly alpha-helical peptide isolated from the skin of the South American frog Phyllomedusa bicolor, we found that the ion specificity of its pores induced in bilayers is modulated by phospholipid-charged headgroups. This suggests mixed lipid-peptide pore lining instead of the more classical barrel-stave model. Macroscopic conductance is nearly voltage independent, and concentration dependence suggests that the pores are mainly formed by dermaseptin tetramers. The two most probable single-channel events are well resolved at 200 and 500 pS (in 150 mM NaCl) with occasional other equally spaced higher or lower levels. In contrast to previous molecular dynamics previsions, this study demonstrates that dermaseptins are able to form pores, although a related analog (B6) failed to induce any significant conductance. Finally, the model of the pore we present accounts for phospholipid headgroups intercalated between peptide helices lining the pore and for one of the most probable single-channel conductance.

Concentration dependences of the physicochemical properties of a water-acetone system

NASA Astrophysics Data System (ADS)

Fedyaeva, O. A.; Poshelyuzhnaya, E. G.

2017-01-01

Concentration dependences of the UV spectrum, refractive index, specific electrical conductivity, boiling point, pH, surface tension, and heats of dissolution of a water-acetone system on the amount of acetone in the water are studied. It is found that the reversible protolytic interaction of the components occurs in all such solutions, resulting in the formation of hydroxyl and acetonium ions. It is shown that shifts of the equilibrium between the molecules and ions in the solution leads to extreme changes in their electrical properties. It is concluded that the formation of acetone solutions of water is accompanied by heat absorption, while the formation of aqueous solutions of acetone is accompanied by heat release.

A simplified design of the staggered herringbone micromixer for practical applications

PubMed Central

Du, Yan; Zhang, Zhiyi; Yim, ChaeHo; Lin, Min; Cao, Xudong

2010-01-01

We demonstrated a simple method for the device design of a staggered herringbone micromixer (SHM) using numerical simulation. By correlating the simulated concentrations with channel length, we obtained a series of concentration versus channel length profiles, and used mixing completion length Lm as the only parameter to evaluate the performance of device structure on mixing. Fluorescence quenching experiments were subsequently conducted to verify the optimized SHM structure for a specific application. Good agreement was found between the optimization and the experimental data. Since Lm is straightforward, easily defined and calculated parameter for characterization of mixing performance, this method for designing micromixers is simple and effective for practical applications. PMID:20697584

A simplified design of the staggered herringbone micromixer for practical applications.

PubMed

Du, Yan; Zhang, Zhiyi; Yim, Chaeho; Lin, Min; Cao, Xudong

2010-05-07

We demonstrated a simple method for the device design of a staggered herringbone micromixer (SHM) using numerical simulation. By correlating the simulated concentrations with channel length, we obtained a series of concentration versus channel length profiles, and used mixing completion length L(m) as the only parameter to evaluate the performance of device structure on mixing. Fluorescence quenching experiments were subsequently conducted to verify the optimized SHM structure for a specific application. Good agreement was found between the optimization and the experimental data. Since L(m) is straightforward, easily defined and calculated parameter for characterization of mixing performance, this method for designing micromixers is simple and effective for practical applications.

Profiling Groundwater Salt Concentrations in Mangrove Swamps and Tropical Salt Flats

NASA Astrophysics Data System (ADS)

Ridd, Peter V.; Sam, Renagi

1996-11-01

The salt concentration of groundwater in mangrove swamps is an important parameter controlling the growth of mangrove species. Extremely high salt concentrations of groundwater in tropical salt flats are responsible for the complete absence of macrophytes. Determining groundwater salt concentrations can be a very time-consuming and laborious process if conventional techniques are used. Typically, groundwater samples must be extracted for later laboratory analysis. In this work, a simple conductivity probe has been developed which may be inserted easily to a depth of 2 m into the sediment. The changes in conductivity of the sediment is due primarily to porewater salt concentration, and thus ground conductivity is useful in determining changes in groundwater salt concentrations. Using the conductivity probe, transects of sediment conductivity can be undertaken quickly. As an example of a possible application of the probe, transects of ground conductivity were taken on a mangrove swamp/saltflat system. The transects show clearly the sharp delineation in conductivity between the salt flat and mangrove swamp due to a change in groundwater salt concentrations. Horizontal and vertical salt concentration gradients of up to 50 g l -1 m -1and 150 g l -1 m -1, respectively, were found. Very sharp changes in groundwater salt concentrations at the interface between salt flats and mangroves indicate that the mangroves may be modifying the salinity of the groundwater actively.

Effects of pipette modulation and imaging distances on ion currents measured with scanning ion conductance microscopy (SICM).

PubMed

Chen, Chiao-Chen; Baker, Lane A

2011-01-07

Local conductance variations can be estimated by measuring ion current magnitudes with scanning ion conductance microscopy (SICM). Factors which influence image quality and quantitation of ion currents measured with SICM have been evaluated. Specifically, effects of probe-sample separation and pipette modulation have been systematically studied for the case of imaging conductance variations at pores in a polymer membrane under transmembrane concentration gradients. The influence of probe-sample separation on ion current images was evaluated using distance-modulated (ac) feedback. Approach curves obtained using non-modulated (dc) feedback were also recorded to determine the relative influence of pipette-generated convection by comparison of ion currents measured with both ac and dc feedback modes. To better interpret results obtained, comparison to a model based on a disk-shaped geometry for nanopores in the membrane, as well as relevant position-dependent parameters of the experiment is described. These results advance our current understanding of conductance measurements with SICM.

Exchange of NO2 between spruces and the atmosphere is dominated by deposition

NASA Astrophysics Data System (ADS)

Breuninger, C.; Meixner, F. X.; Kesselmeier, J.

2009-04-01

The chemical budget of troposheric ozone is largely determined by the concentration of NOx (NO and NO2), which is in remote areas related to biological activities of soils and vegetation. The atmospheric concentration of NO2 is strongly influenced by the bi-directional exchange between the atmosphere and plants. The exchange depends on stomatal compensations points in close relation to the NO2 concentrations in ambient air. It is accepted that NO2 uptake by plants represents a large NO2 sink, but the magnitude is still unidentified. A better knowledge of compensation point values for the bi-directional NO2 exchange is a matter of recent discussions, as accurate estimates would help to reliably classify vegetation types. In close relation to our previous studies of Betula pendula, Fagus sylvatica, Quercus ilex und Pinus sylvestris we investigated a further representative of conifers, Picea abies, under field and laboratory conditions. The measurements were part of the DFG joined project EGER (ExchanGE processes in mountainous Regions). We used dynamic chambers and a sensitive and highly specific NO-NO2-Analysator. CO¬2 and H2O exchange were measured simultaneously to assess physiological comparative parameters such as photosynthesis, transpiration and stomatal conductance. Additionally O3 concentrations were recorded, to detect and estimate chemical reactions within the chamber. During the measurements the NO2 exchange was obviously dominated by deposition and depended on stomatal conductance.

Critical review of heavy metal pollution of traffic area runoff: Occurrence, influencing factors, and partitioning.

PubMed

Huber, Maximilian; Welker, Antje; Helmreich, Brigitte

2016-01-15

A dataset of 294 monitored sites from six continents (Africa, Asia, Australia, Europe, North and South America) was compiled and evaluated to characterize the occurrence and fate of heavy metals in eight traffic area categories (parking lots, bridges, and three types each of both roads and highways). In addition, site-specific (fixed and climatic) and method-specific (related to sample collection, preparation, and analysis) factors that influence the results of the studies are summarized. These factors should be considered in site descriptions, conducting monitoring programs, and implementing a database for further research. Historical trends for Pb show a sharp decrease during recent decades, and the median total Pb concentrations of the 21st century for North America and Europe are approximately 15 μg/L. No historical trend is detected for Zn. Zn concentrations are very variable in traffic area runoff compared with other heavy metals because of its presence in galvanized structures and crumbs of car tire rubber. Heavy metal runoff concentrations of parking lots differ widely according to their use (e.g., employee, supermarket, rest areas for trucks). Bridge deck runoff can contain high Zn concentrations from safety fences and galvanizing elements. Roads with more than 5000 vehicles per day are often more polluted than highways because of other site-specific factors such as traffic signals. Four relevant heavy metals (Zn, Cu, Ni, and Cd) can occur in the dissolved phase. Knowledge of metal partitioning is important to optimize stormwater treatment strategies and prevent toxic effects to organisms in receiving waters. Copyright © 2015 Elsevier B.V. All rights reserved.

Associations between Source-Specific Fine Particulate Matter and Emergency Department Visits for Respiratory Disease in Four U.S. Cities

PubMed Central

Krall, Jenna R.; Mulholland, James A.; Russell, Armistead G.; Balachandran, Sivaraman; Winquist, Andrea; Tolbert, Paige E.; Waller, Lance A.; Sarnat, Stefanie Ebelt

2016-01-01

Background: Short-term exposure to ambient fine particulate matter (PM2.5) concentrations has been associated with increased mortality and morbidity. Determining which sources of PM2.5 are most toxic can help guide targeted reduction of PM2.5. However, conducting multicity epidemiologic studies of sources is difficult because source-specific PM2.5 is not directly measured, and source chemical compositions can vary between cities. Objectives: We determined how the chemical composition of primary ambient PM2.5 sources varies across cities. We estimated associations between source-specific PM2.5 and respiratory disease emergency department (ED) visits and examined between-city heterogeneity in estimated associations. Methods: We used source apportionment to estimate daily concentrations of primary source-specific PM2.5 for four U.S. cities. For sources with similar chemical compositions between cities, we applied Poisson time-series regression models to estimate associations between source-specific PM2.5 and respiratory disease ED visits. Results: We found that PM2.5 from biomass burning, diesel vehicle, gasoline vehicle, and dust sources was similar in chemical composition between cities, but PM2.5 from coal combustion and metal sources varied across cities. We found some evidence of positive associations of respiratory disease ED visits with biomass burning PM2.5; associations with diesel and gasoline PM2.5 were frequently imprecise or consistent with the null. We found little evidence of associations with dust PM2.5. Conclusions: We introduced an approach for comparing the chemical compositions of PM2.5 sources across cities and conducted one of the first multicity studies of source-specific PM2.5 and ED visits. Across four U.S. cities, among the primary PM2.5 sources assessed, biomass burning PM2.5 was most strongly associated with respiratory health. Citation: Krall JR, Mulholland JA, Russell AG, Balachandran S, Winquist A, Tolbert PE, Waller LA, Sarnat SE. 2017. Associations between source-specific fine particulate matter and emergency department visits for respiratory disease in four U.S. cities. Environ Health Perspect 125:97–103; http://dx.doi.org/10.1289/EHP271 PMID:27315241

Associations between Source-Specific Fine Particulate Matter and Emergency Department Visits for Respiratory Disease in Four U.S. Cities.

PubMed

Krall, Jenna R; Mulholland, James A; Russell, Armistead G; Balachandran, Sivaraman; Winquist, Andrea; Tolbert, Paige E; Waller, Lance A; Sarnat, Stefanie Ebelt

2017-01-01

Short-term exposure to ambient fine particulate matter (PM2.5) concentrations has been associated with increased mortality and morbidity. Determining which sources of PM2.5 are most toxic can help guide targeted reduction of PM2.5. However, conducting multicity epidemiologic studies of sources is difficult because source-specific PM2.5 is not directly measured, and source chemical compositions can vary between cities. We determined how the chemical composition of primary ambient PM2.5 sources varies across cities. We estimated associations between source-specific PM2.5 and respiratory disease emergency department (ED) visits and examined between-city heterogeneity in estimated associations. We used source apportionment to estimate daily concentrations of primary source-specific PM2.5 for four U.S. cities. For sources with similar chemical compositions between cities, we applied Poisson time-series regression models to estimate associations between source-specific PM2.5 and respiratory disease ED visits. We found that PM2.5 from biomass burning, diesel vehicle, gasoline vehicle, and dust sources was similar in chemical composition between cities, but PM2.5 from coal combustion and metal sources varied across cities. We found some evidence of positive associations of respiratory disease ED visits with biomass burning PM2.5; associations with diesel and gasoline PM2.5 were frequently imprecise or consistent with the null. We found little evidence of associations with dust PM2.5. We introduced an approach for comparing the chemical compositions of PM2.5 sources across cities and conducted one of the first multicity studies of source-specific PM2.5 and ED visits. Across four U.S. cities, among the primary PM2.5 sources assessed, biomass burning PM2.5 was most strongly associated with respiratory health. Citation: Krall JR, Mulholland JA, Russell AG, Balachandran S, Winquist A, Tolbert PE, Waller LA, Sarnat SE. 2017. Associations between source-specific fine particulate matter and emergency department visits for respiratory disease in four U.S. cities. Environ Health Perspect 125:97-103; http://dx.doi.org/10.1289/EHP271.

Role of sampling times and serum cortisol cut-off concentrations on the routine assessment of adrenal function using the standard cosyntropin test in an academic hospital from Spain: a retrospective chart review.

PubMed

Ortiz-Flores, Andrés E; Santacruz, Elisa; Jiménez-Mendiguchia, Lucía; García-Cano, Ana; Nattero-Chávez, Lia; Escobar-Morreale, Héctor F; Luque-Ramírez, Manuel

2018-05-05

Aiming to validate the use of a single poststimulus sampling protocol for cosyntropin test short standard high-dose test (SST) in our institution, our primary objectives were (1) to determine the concordance between 30 and 60 min serum cortisol (SC) measurements during SST; and (2) to evaluate the diagnostic agreement between both sampling times when using classic or assay-specific and sex-specific SC cut-off values. The secondary objectives included (1) estimating the specificity and positive predictive value of 30 and 60 min sampling times while considering the suspected origin of adrenal insufficiency (AI); and (2) obtaining assay-specific cut-off values for SC after SST in a group of subjects with normal hypothalamic-pituitary-adrenal (HPA) axis. This is a retrospective chart review study conducted at a Spanish academic hospital from 2011 to 2015. Two groups were evaluated: (1) a main study group including 370 patients in whom SC was measured at 30 and 60 min during SST; and (2) a confirmative group that included 150 women presenting with a normal HPA axis in whom SST was conducted to rule out late-onset congenital adrenal hyperplasia. Diagnostic agreement between both sampling times was assessed by considering both classic (500 nmol/L) and assay-specific SC cut-off concentrations. Diagnostic agreement between both sampling times was greater when applying sex-specific and assay-specific cut-off values instead of the classic cut-off values. For suspected primary AI, 30 min SC determination was enough to establish a diagnosis in over 95% of cases, without missing any necessary treatment. When central AI is suspected, 60 min SC measurement was more specific, establishing a diagnosis in over 97% of cases. Sex-specific and assay-specific SC cut-off values improve the diagnostic accuracy of SST. For primary disease, a subnormal SC response at 30 min is a reliable marker of adrenal dysfunction. On the contrary, when central AI is suspected, 60 min SC measurement improves the diagnostic accuracy of the test. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Lung Microtissue Array to Screen the Fibrogenic Potential of Carbon Nanotubes

PubMed Central

Chen, Zhaowei; Wang, Qixin; Asmani, Mohammadnabi; Li, Yan; Liu, Chang; Li, Changning; Lippmann, Julian M.; Wu, Yun; Zhao, Ruogang

2016-01-01

Due to their excellent physical and chemical characteristics, multi-wall carbon nanotubes (MWCNT) have the potential to be used in structural composites, conductive materials, sensors, drug delivery and medical imaging. However, because of their small-size and light-weight, the applications of MWCNT also raise health concerns. In vivo animal studies have shown that MWCNT cause biomechanical and genetic alterations in the lung tissue which lead to lung fibrosis. To screen the fibrogenic risk factor of specific types of MWCNT, we developed a human lung microtissue array device that allows real-time and in-situ readout of the biomechanical properties of the engineered lung microtissue upon MWCNT insult. We showed that the higher the MWCNT concentration, the more severe cytotoxicity was observed. More importantly, short type MWCNT at low concentration of 50 ng/ml stimulated microtissue formation and contraction force generation, and caused substantial increase in the fibrogenic marker miR-21 expression, indicating the high fibrogenic potential of this specific carbon nanotube type and concentration. The presented microtissue array system provides a powerful tool for high-throughput examination of the therapeutic and toxicological effects of target compounds in realistic tissue environment. PMID:27510174

Electrical properties of methane hydrate + sediment mixtures

USGS Publications Warehouse

Du Frane, Wyatt L.; Stern, Laura A.; Constable, Steven; Weitemeyer, Karen A.; Smith, Megan M; Roberts, Jeffery J.

2015-01-01

Knowledge of the electrical properties of multicomponent systems with gas hydrate, sediments, and pore water is needed to help relate electromagnetic (EM) measurements to specific gas hydrate concentration and distribution patterns in nature. Toward this goal, we built a pressure cell capable of measuring in situ electrical properties of multicomponent systems such that the effects of individual components and mixing relations can be assessed. We first established the temperature-dependent electrical conductivity (σ) of pure, single-phase methane hydrate to be ~5 orders of magnitude lower than seawater, a substantial contrast that can help differentiate hydrate deposits from significantly more conductive water-saturated sediments in EM field surveys. Here we report σ measurements of two-component systems in which methane hydrate is mixed with variable amounts of quartz sand or glass beads. Sand by itself has low σ but is found to increase the overall σ of mixtures with well-connected methane hydrate. Alternatively, the overall σ decreases when sand concentrations are high enough to cause gas hydrate to be poorly connected, indicating that hydrate grains provide the primary conduction path. Our measurements suggest that impurities from sand induce chemical interactions and/or doping effects that result in higher electrical conductivity with lower temperature dependence. These results can be used in the modeling of massive or two-phase gas-hydrate-bearing systems devoid of conductive pore water. Further experiments that include a free water phase are the necessary next steps toward developing complex models relevant to most natural systems.

How Analysis Informs Regulation:Success and Failure of ...

EPA Pesticide Factsheets

How Analysis Informs Regulation:Success and Failure of Evolving Approaches to Polyfluoroalkyl Acid Contamination The National Exposure Research Laboratory (NERL) Human Exposure and Atmospheric Sciences Division (HEASD) conducts research in support of EPA mission to protect human health and the environment. HEASD research program supports Goal 1 (Clean Air) and Goal 4 (Healthy People) of EPA strategic plan. More specifically, our division conducts research to characterize the movement of pollutants from the source to contact with humans. Our multidisciplinary research program produces Methods, Measurements, and Models to identify relationships between and characterize processes that link source emissions, environmental concentrations, human exposures, and target-tissue dose. The impact of these tools is improved regulatory programs and policies for EPA.

Developing Decontamination Tools and Approaches to ...

EPA Pesticide Factsheets

Developing Decontamination Tools and Approaches to Address Indoor Pesticide Contamination from Improper Bed Bug Treatments The National Exposure Research Laboratory (NERL) Human Exposure and Atmospheric Sciences Division (HEASD) conducts research in support of EPA mission to protect human health and the environment. HEASD research program supports Goal 1 (Clean Air) and Goal 4 (Healthy People) of EPA strategic plan. More specifically, our division conducts research to characterize the movement of pollutants from the source to contact with humans. Our multidisciplinary research program produces Methods, Measurements, and Models to identify relationships between and characterize processes that link source emissions, environmental concentrations, human exposures, and target-tissue dose. The impact of these tools is improved regulatory programs and policies for EPA.

Detection of α-fetoprotein in human serum using carbon nanotube transistor

NASA Astrophysics Data System (ADS)

So, Hye-Mi; Park, Dong-Won; Lee, Seong-Kyu; Kim, Beom Soo; Chang, Hyunju; Lee, Jeong-O.

2009-03-01

We have fabricated antibody-coated carbon nanotube field effect transistor (CNT-FET) sensor for the detection of α-fetoprotein (AFP), single chain glycoprotein of 70 kDa that is normally expressed in the fetal liver, in human serum. The AFP-specific antibodies were immobilized on CNT with linker molecule such as pyrenebutyric acid N-hydroxysuccinimide ester. To prevent nonspecific adsorption of antigen, we performed blocking procedure using bovine serum albumin (BSA). Antibody-antigen binding was determined by measuring electrical conductance change of FET and took an average of thereshold voltage change before and after binding. Also we checked concentration-dependent conductance change in human serum using both p-type SWNT-FETs and n-type SWNT-FETs.

A Method for Improved Interpretation of "Spot" Biomarker Data ...

EPA Pesticide Factsheets

A Method for Improved Interpretation of "Spot" Biomarker Data The National Exposure Research Laboratory (NERL) Human Exposure and Atmospheric Sciences Division (HEASD) conducts research in support of EPA mission to protect human health and the environment. HEASD research program supports Goal 1 (Clean Air) and Goal 4 (Healthy People) of EPA strategic plan. More specifically, our division conducts research to characterize the movement of pollutants from the source to contact with humans. Our multidisciplinary research program produces Methods, Measurements, and Models to identify relationships between and characterize processes that link source emissions, environmental concentrations, human exposures, and target-tissue dose. The impact of these tools is improved regulatory programs and policies for EPA.

Trends in the quality of water in New Jersey streams, water years 1971–2011

USGS Publications Warehouse

Hickman, R. Edward; Hirsch, Robert M.

2017-02-27

In a study conducted by the U.S. Geological Survey in cooperation with the New Jersey Department of Environmental Protection and the Delaware River Basin Commission, trend tests were conducted on selected water-quality characteristics measured at stations on streams in New Jersey during selected periods over water years 1971‒2011. Tests were conducted on 3 nutrients (total nitrogen, filtered nitrate plus nitrite, and total phosphorus) at 28 water-quality stations. At 4 of these stations, tests were also conducted on 3 measures of major ions (specific conductance, filtered chloride, and total dissolved solids).Two methods were used to identify trends—Weighted Regressions on Time, Discharge, and Season (WRTDS) models and seasonal rank-sum tests. For this report, the use of WRTDS models included the use of the WRTDS Bootstrap Test (WBT). WRTDS models identified trends in flow-normalized annual concentrations and flow-normalized annual fluxes over water years 1980‒2011 and 2000‒11 for each nutrient, filtered chloride, and total dissolved solids. WRTDS models were developed for each nutrient at the 20 or 21 stations at which streamflow was measured or estimated. Trends in nutrient concentration were reported for these stations; trends in nutrient fluxes were reported only for 15–17 of these stations.The results of WRTDS models for water years 1980‒2011 identified more stations with downward trends in concentrations of either total nitrogen or total phosphorus than upward trends. For total nitrogen, there were downward trends at 9 stations and an upward trend at 1 station. For total phosphorus, there were downward trends at 8 stations and an upward trend at 1 station. For filtered nitrate plus nitrite, there were downward trends at 6 stations and upward trends at 6 stations. The result of the trend test in flux for a selected nutrient at a selected station (downward trend, no trend, or upward trend) usually matched the trend result in concentration.Seasonal rank-sum tests, the second method used, identified step trends in water-quality measured in different decades—1970s, 1980s, 1990s, and 2000s. Tests were conducted on all nutrients at 28 stations and on all measures of major ions at the 4 selected stations. Results of seasonal rank-sum tests between the 1980s and the 2000s identified more stations with downward trends in concentrations of total nitrogen (14) than stations with upward trends (2) and more stations with downward trends in concentrations of total phosphorus (18) than stations with upward trends (1).A combined dataset of trend results for concentrations over water years 1980‒2011 was created from the results of the two tests for the period. Results of WRTDS models were included in this combined dataset, if available. Otherwise, the results of the seasonal rank-sum tests between water-quality characteristics measured in the 1980s and 2000s were included.Trend results over water years 1980‒2011 in the combined dataset show that few of the 28 stations had upward trends in concentrations of either total nitrogen or total phosphorus. There were only 2 stations with upward trends in total nitrogen concentration and 1 station with an upward trend in total phosphorus concentration. Results for filtered nitrate plus nitrite show about the same number of stations with upward trends (9) as stations with downward trends (7). Results for all measures of major ions show upward trends at the four stations tested.

Species-specific accumulation of polybrominated diphenyl ethers (PBDEs) and other emerging flame retardants in several species of birds from Korea.

PubMed

Jin, Xiangzi; Lee, Sunggyu; Jeong, Yunsun; Yu, Jae-Pyoung; Baek, Woon Kee; Shin, Kyung-Hoon; Kannan, Kurunthachalam; Moon, Hyo-Bang

2016-12-01

Few studies have been conducted on the alternatives to legacy flame retardants in avian species worldwide. In this study, polybrominated diphenyl ethers (PBDEs) and alternative flame retardants such as novel brominated flame retardants (NBFRs) and dechlorane plus (DP) were determined in livers of 10 species of birds from Korea to elucidate species-specific accumulation, biological factors that affect accumulation, and bioaccumulation potentials of these contaminants. Among the emerging alternative flame retardants, the highest occurrence was found for bis(2-ethylhexyl)-3,4,5,6-tetrabromo-phthalate (BEHTBP), syn-DP, anti-DP, and decabromodiphenyl ethane (DBDPE). PBDE concentrations (median: 17.1 ng/g lipid wt) measured in our study were within the ranges reported in previous studies, while the concentrations of BEHTBP, BTBPE and DP were greater than those reported earlier. Residential predatory birds showed significantly greater concentrations of PBDEs and NBFRs than migratory predators and passerine birds. The concentrations of PBDEs, BEHTBP, and DP in residential predatory birds were significantly correlated with increasing stable nitrogen isotope ratio (δ 15 N), which indicated biomagnification potentials of these contaminants. Our results suggest that the concentrations and accumulation patterns of PBDEs, NBFRs, and DP depend on the feeding habits and migration patterns of avian species. This is the first report on the accumulation of emerging alternatives to PBDEs in birds from Korea. Copyright © 2016 Elsevier Ltd. All rights reserved.

Enhancement of hexavalent chromium reduction and electricity production from a biocathode microbial fuel cell.

PubMed

Huang, Liping; Chen, Jingwen; Quan, Xie; Yang, Fenglin

2010-10-01

Enhancement of Cr (VI) reduction rate and power production from biocathode microbial fuel cells (MFCs) was achieved using indigenous bacteria from Cr (VI)-contaminated site as inoculum and MFC architecture with a relatively large cathode-specific surface area of 340-900 m2 m(-3). A specific Cr (VI) reduction rate of 2.4 ± 0.2 mg g(-1)VSS h(-1) and a power production of 2.4 ± 0.1 W m(-3) at a current density of 6.9 A m(-3) were simultaneously achieved at an initial Cr (VI) concentration of 39.2 mg L(-1). Initial Cr (VI) concentration and solution conductivity affected Cr (VI) reduction rate, power production and coulombic efficiency. These findings demonstrate the importance of inoculation and MFC architecture in the enhancement of Cr (VI) reduction rate and power production. This study is a beneficial attempt to improve the efficiency of biocathode MFCs and provide a good candidate of bioremediation process for Cr (VI)-contaminated sites.

Evaluation of weapons' combustion products in armored vehicles. Appendix C: Summary of descriptive statistics (proc tabulate). Appendix D: Summary of comparative statistics. Final report, 30 September 1986-14 December 1988

DOE Office of Scientific and Technical Information (OSTI.GOV)

Menzies, K.T.; Randel, M.A.; Quill, A.L.

1989-01-01

The U.S. Army Biomedical Research and Development Laboratory defined an extensive research program to address the generation of potentially toxic propellant combustion products in crew compartments of armored vehicles during weapons firing. The major objectives of the research were (1) to determine the presence and concentration of propellant combustion products, (2) to determine potential crew exposure to these combustion products, and (3) to assess the efficacy of field monitoring in armored vehicles. To achieve these goals, air monitoring was conducted in selected armored vehicle types, i.e., M109, M60, M3, M1, at several Army installations. Auxiliary information concerning the specific munitionsmore » fired and the Training and Doctrine Command (TRADOC) or Forces Command (FORSCOM) firing scenarios was collected so that a comparison of pollutant concentrations generated by specific weapons both within vehicle types and between vehicle types could be made.« less

Quantum dot-based microfluidic biosensor for cancer detection

NASA Astrophysics Data System (ADS)

Ghrera, Aditya Sharma; Pandey, Chandra Mouli; Ali, Md. Azahar; Malhotra, Bansi Dhar

2015-05-01

We report results of the studies relating to fabrication of an impedimetric microfluidic-based nucleic acid sensor for quantification of DNA sequences specific to chronic myelogenous leukemia (CML). The sensor chip is prepared by patterning an indium-tin-oxide (ITO) coated glass substrate via wet chemical etching method followed by sealing with polydimethylsiloxane (PDMS) microchannel for fluid control. The fabricated microfluidic chip comprising of a patterned ITO substrate is modified by depositing cadmium selenide quantum dots (QCdSe) via Langmuir-Blodgett technique. Further, the QCdSe surface has been functionalized with specific DNA probe for CML detection. The probe DNA functionalized QCdSe integrated miniaturized system has been used to monitor target complementary DNA concentration by measuring the interfacial charge transfer resistance via hybridization. The presence of complementary DNA in buffer solution significantly results in decreased electro-conductivity of the interface due to presence of a charge barrier for transport of the redox probe ions. The microfluidic DNA biosensor exhibits improved linearity in the concentration range of 10-15 M to 10-11 M.

AlMn Transition Edge Sensors for Advanced ACTPol

NASA Technical Reports Server (NTRS)

Li, Dale; Austermann, Jason E.; Beall, James A.; Tucker, Daniel T.; Duff, Shannon M.; Gallardo, Patricio A.; Henderson, Shawn W.; Hilton, Gene C.; Ho, Shuay-Pwu; Hubmayr, Johannes;

AlMn Transition Edge Sensors for Advanced ACTPol

NASA Astrophysics Data System (ADS)

Li, Dale; Austermann, Jason E.; Beall, James A.; Becker, Daniel T.; Duff, Shannon M.; Gallardo, Patricio A.; Henderson, Shawn W.; Hilton, Gene C.; Ho, Shuay-Pwu; Hubmayr, Johannes; Koopman, Brian J.; McMahon, Jeffrey J.; Nati, Federico; Niemack, Michael D.; Pappas, Christine G.; Salatino, Maria; Schmitt, Benjamin L.; Simon, Sara M.; Staggs, Suzanne T.; Van Lanen, Jeff; Ward, Jonathan T.; Wollack, Edward J.

2016-07-01

Advanced ACTPol (AdvACT) will use an array of multichroic polarization-sensitive AlMn transition edge sensor (TES) bolometers read out through time-division multiplexing. Aluminum doped with a low concentration of manganese can be deposited to a bulk film thickness for a more reliable superconducting critical temperature uniformity compared to thin bilayers. To build the TES, the AlMn alloy is deposited, over Nb wiring, to a specific thickness to set the TES normal resistance. The doping concentration of manganese coarsely defines the TES critical temperature, while a fine tuning is achieved by heating the deposited film to a specific temperature. The TES island is connected to the thermal bath via four silicon-nitride membranes, where their geometry defines the thermal conductance to the temperature of the bath. Lastly, the TES heat capacity is increased by addition of PdAu electrically connected to the AlMn film. Designs and performance characteristics of these AlMn TESs are presented for use in AdvACT.

Review and analysis of physical exercise at hormonal and brain level, and its influence on appetite.

PubMed

Gómez Escribano, Laura; Gálvez Casas, Arancha; Escribá Fernández-Marcote, Antonio R; Tárraga López, Pedro; Tárraga Marcos, Loreto

Due to the currently growing rate of obesity, it is important to maintain good control of food intake. The main purpose of the present study is to determine the influence of physical exercise on appetite, changes in hormone concentrations, and changes in certain neuronal regions. To achieve this, a literature search was conducted using different data bases. The results show how exercise produces changes in the appetite perception, in the amount of energy intake, and in different weight-control related hormones, as well as in specific neuronal responses. In conclusion, it can be shown that exercise leads to changes in appetite, hunger, and energy intake. In addition, exercise decreases the ghrelin levels and increases concentrations of leptin. Likewise, it is shown how physical exercise alters the responses of certain neuronal regions after visualizing specific food elements decreasing so the appetite or the intake of them. Copyright © 2017 Sociedad Española de Arteriosclerosis. Publicado por Elsevier España, S.L.U. All rights reserved.

On the inhibition of muscle membrane chloride conductance by aromatic carboxylic acids

PubMed Central

Palade, PT; Barchi, RL

1977-01-01

25 aromatic carboxylic acids which are analogs of benzoic acid were tested in the rat diaphragm preparation for effects on chloride conductance (G(Cl)). Of the 25, 19 were shown to reduce membrane G(Cl) with little effect on other membrane parameters, although their apparent K(i) varied widely. This inhibition was reversible if exposure times were not prolonged. The most effective analog studied was anthracene-9-COOH (9-AC; K(i) = 1.1 x 10(-5) M). Active analogs produced concentration-dependent inhibition of a type consistent with interaction at a single site or group of sites having similar binding affinities, although a correlation could also be shown between lipophilicity and K(i). Structure-activity analysis indicated that hydrophobic ring substitution usually increased inhibitory activity while para polar substitutions reduced effectiveness. These compounds do not appear to inhibit G(Cl) by altering membrane surface charge and the inhibition produced is not voltage dependent. Qualitative characteristics of the I-V relationship for Cl(-) current are not altered. Conductance to all anions is not uniformly altered by these acids as would be expected from steric occlusion of a common channel. Concentrations of 9-AC reducing G(Cl) by more than 90 percent resulted in slight augmentation of G(I). The complete conductance sequence obtained at high levels of 9-AC was the reverse of that obtained under control conditions. Permeability sequences underwent progressive changes with increasing 9-AC concentration and ultimately inverted at high levels of the analog. Aromatic carboxylic acids appear to inhibit G(Cl) by binding to a specific intramembrane site and altering the selectivity sequence of the membrane anion channel. PMID:894246

Fermi Level Manipulation through Native Doping in the Topological Insulator Bi2Se3.

PubMed

Walsh, Lee A; Green, Avery J; Addou, Rafik; Nolting, Westly; Cormier, Christopher R; Barton, Adam T; Mowll, Tyler R; Yue, Ruoyu; Lu, Ning; Kim, Jiyoung; Kim, Moon J; LaBella, Vincent P; Ventrice, Carl A; McDonnell, Stephen; Vandenberghe, William G; Wallace, Robert M; Diebold, Alain; Hinkle, Christopher L

2018-06-08

The topologically protected surface states of three-dimensional (3D) topological insulators have the potential to be transformative for high-performance logic and memory devices by exploiting their specific properties such as spin-polarized current transport and defect tolerance due to suppressed backscattering. However, topological insulator based devices have been underwhelming to date primarily due to the presence of parasitic issues. An important example is the challenge of suppressing bulk conduction in Bi 2 Se 3 and achieving Fermi levels ( E F ) that reside in between the bulk valence and conduction bands so that the topologically protected surface states dominate the transport. The overwhelming majority of the Bi 2 Se 3 studies in the literature report strongly n-type materials with E F in the bulk conduction band due to the presence of a high concentration of selenium vacancies. In contrast, here we report the growth of near-intrinsic Bi 2 Se 3 with a minimal Se vacancy concentration providing a Fermi level near midgap with no extrinsic counter-doping required. We also demonstrate the crucial ability to tune E F from below midgap into the upper half of the gap near the conduction band edge by controlling the Se vacancy concentration using post-growth anneals. Additionally, we demonstrate the ability to maintain this Fermi level control following the careful, low-temperature removal of a protective Se cap, which allows samples to be transported in air for device fabrication. Thus, we provide detailed guidance for E F control that will finally enable researchers to fabricate high-performance devices that take advantage of transport through the topologically protected surface states of Bi 2 Se 3 .

Effect of Cation Ordering on the Performance and Chemical Stability of Layered Double Perovskite Cathodes

PubMed Central

Bernuy-Lopez, Carlos; Rioja-Monllor, Laura; Nakamura, Takashi; Ricote, Sandrine; O’Hayre, Ryan; Amezawa, Koji; Einarsrud, Mari-Ann

2018-01-01

The effect of A-site cation ordering on the cathode performance and chemical stability of A-site cation ordered LaBaCo2O5+δ and disordered La0.5Ba0.5CoO3−δ materials are reported. Symmetric half-cells with a proton-conducting BaZr0.9Y0.1O3−δ electrolyte were prepared by ceramic processing, and good chemical compatibility of the materials was demonstrated. Both A-site ordered LaBaCo2O5+δ and A-site disordered La0.5Ba0.5CoO3−δ yield excellent cathode performance with Area Specific Resistances as low as 7.4 and 11.5 Ω·cm2 at 400 °C and 0.16 and 0.32 Ω·cm2 at 600 °C in 3% humidified synthetic air respectively. The oxygen vacancy concentration, electrical conductivity, basicity of cations and crystal structure were evaluated to rationalize the electrochemical performance of the two materials. The combination of high-basicity elements and high electrical conductivity as well as sufficient oxygen vacancy concentration explains the excellent performance of both LaBaCo2O5+δ and La0.5Ba0.5CoO3−δ materials at high temperatures. At lower temperatures, oxygen-deficiency in both materials is greatly reduced, leading to decreased performance despite the high basicity and electrical conductivity. A-site cation ordering leads to a higher oxygen vacancy concentration, which explains the better performance of LaBaCo2O5+δ. Finally, the more pronounced oxygen deficiency of the cation ordered polymorph and the lower chemical stability at reducing conditions were confirmed by coulometric titration. PMID:29373541

Water-quality and amphibian population data for Maryland, Washington, D.C., and Virginia, 2001-2004

USGS Publications Warehouse

Rice, K.C.; Jung, R.E.

2004-01-01

Data on the chemical composition of water and on amphibian populations were collected at least annually from vernal pool and stream sites in Maryland, Washington, D.C., and Virginia, from 2001 through 2004. The data were collected as part of long-term monitoring projects of the Northeast Region of the Amphibian Research and Monitoring Initiative (ARMI) of the U.S. Geological Survey. Water samples were analyzed for temperature, specific conductance, pH, dissolved-oxygen concentration, acid-neutralizing capacity, and concentrations of total Kjeldahl nitrogen and total phosphorus; in 2004, samples also were analyzed for nitrite plus nitrate concentrations and total nitrogen concentrations. Field and laboratory analytical results of water samples and quality-assurance information are presented. Amphibian population data include the presence of amphibian species and the maximum number of egg masses of wood frogs and spotted salamanders at vernal pools, and counts of amphibians made during stream transect and stream quadrat surveys.

LUSH-based SPR sensor for the detection of alcohols and pheromone

NASA Astrophysics Data System (ADS)

Lau, Hui-Chong; Lee, Yeon-Kyung; Kwon, Jae-Young; Sohn, Young-Soo; Lim, Jeong Ok

2013-05-01

Protein is a widely used sensing substrate in the biosensing technology. In the study conducted here, we used odorant binding protein, LUSH from Drosophila as a biosensing substrate in a miniaturized surface plasmon resonance (SPR) sensor. LUSH contains the specific alcohols binding sites, which mediates the detection of alcohols and pheromone. We first modified the surface of the gold sensor chip using the self assembled monolayer in the chloroform solution. The saturated concentration was determined prior to the detection of alcohols and pheromone at various concentrations. The results showed that the LUSH was saturated at 1000 μg/ml on the gold sensor chip. The detection response of LUSH was significant at higher concentration of alcohols. LUSH detected ethanol at concentration >=50% propanol was detected at >=25% whereas pheromone was detected at >=1.25 μg/μl. The results provide some fundamental information on the potential use of LUSH-based SPR as a simple and easy protein-based sensor in the near future.

Water quality in the Sugar Creek basin, Bloomington and Normal, Illinois

USGS Publications Warehouse

Prugh, Byron J.

1978-01-01

Urban runoff and overflows from combined sewers affect water quantity and quality in Sugar Creek within the twin cities of Bloomington and Normal, Illinois. Water-quality data from five primary and eight secondary locations showed three basic types of responses to climatic and hydrologic stresses. Stream temperatures and concentrations of dissolved oxygen, ammonia nitrogen, total phosphorus, biochemical oxygen demand, and fecal bacteria showed seasonal variations. Specific conductivity, pH, chloride, and suspended solids concentrations varied more closely with stream discharges. Total organic carbon, total nitrogen, total phosphorus, biochemical oxygen demand, and fecal coliform and fecal streptococcal bacteria concentrations exhibited variations indicative of intial flushing action during storm runoff. Selected analyses for herbicides, insecticides, and other complex organic compounds in solution and in bed material showed that these constituents were coming from sources other than the municipal sanitary treatment plant effluent. Analyses for 10 common metals: arsenic, cadmium, chromium, copper, iron, lead, manganese, mercury, nickel, and zinc showed changes in concentrations below the municipal sanitary plant outfall. (Woodard-USGS)

Propagation of three-dimensional bipolar ultrashort electromagnetic pulses in an inhomogeneous array of carbon nanotubes

NASA Astrophysics Data System (ADS)

Fedorov, Eduard G.; Zhukov, Alexander V.; Bouffanais, Roland; Timashkov, Alexander P.; Malomed, Boris A.; Leblond, Hervé; Mihalache, Dumitru; Rosanov, Nikolay N.; Belonenko, Mikhail B.

2018-04-01

We study the propagation of three-dimensional (3D) bipolar ultrashort electromagnetic pulses in an inhomogeneous array of semiconductor carbon nanotubes. The heterogeneity is represented by a planar region with an increased concentration of conduction electrons. The evolution of the electromagnetic field and electron concentration in the sample are governed by the Maxwell's equations and continuity equation. In particular, nonuniformity of the electromagnetic field along the axis of the nanotubes is taken into account. We demonstrate that depending on values of the parameters of the electromagnetic pulse approaching the region with the higher electron concentration, the pulse is either reflected from the region or passes it. Specifically, our simulations demonstrate that after interacting with the higher-concentration area, the pulse can propagate steadily, without significant spreading. The possibility of such ultrashort electromagnetic pulses propagating in arrays of carbon nanotubes over distances significantly exceeding characteristic dimensions of the pulses makes it possible to consider them as 3D solitons.

Modelling daily dissolved oxygen concentration using least square support vector machine, multivariate adaptive regression splines and M5 model tree

NASA Astrophysics Data System (ADS)

Heddam, Salim; Kisi, Ozgur

2018-04-01

In the present study, three types of artificial intelligence techniques, least square support vector machine (LSSVM), multivariate adaptive regression splines (MARS) and M5 model tree (M5T) are applied for modeling daily dissolved oxygen (DO) concentration using several water quality variables as inputs. The DO concentration and water quality variables data from three stations operated by the United States Geological Survey (USGS) were used for developing the three models. The water quality data selected consisted of daily measured of water temperature (TE, °C), pH (std. unit), specific conductance (SC, μS/cm) and discharge (DI cfs), are used as inputs to the LSSVM, MARS and M5T models. The three models were applied for each station separately and compared to each other. According to the results obtained, it was found that: (i) the DO concentration could be successfully estimated using the three models and (ii) the best model among all others differs from one station to another.

Rocky Mountain snowpack physical and chemical data for selected sites, 2009

USGS Publications Warehouse

Ingersoll, George P.; Mast, M. Alisa; Swank, James M.; Campbell, Chelsea D.

2010-01-01

The Rocky Mountain Snowpack program established a network of snowpack-sampling sites in the Rocky Mountain region from New Mexico to Montana to monitor the chemical content of snow and to understand the effects of regional atmospheric deposition. The U.S. Geological Survey, in cooperation with the National Park Service; the U.S. Department of Agriculture Forest Service; the Colorado Department of Public Health and Environment; Teton County, Wyoming; and others, collected and analyzed snowpack samples annually for 48 or more sites in the Rocky Mountain region during 1993-2009. Sixty-three snowpack-sampling sites were sampled once each in 2009 and data are presented in this report. Data include acid-neutralization capacity, specific conductance, pH, hydrogen ion concentrations, dissolved concentrations of major constituents (calcium, magnesium, sodium, potassium, ammonium, chloride, sulfate, and nitrate), dissolved organic carbon concentrations, snow-water equivalent, snow depth, total mercury concentrations, and ionic charge balance. Quality-assurance data for field and laboratory blanks and field replicates for 2009 also are included.

The Effects of Elevated Specific Conductivity on the Chronic Toxicity of Mining Influenced Streams Using Ceriodaphnia dubia

PubMed Central

Armstead, Mindy Yeager; Bitzer-Creathers, Leah; Wilson, Mandee

2016-01-01

Salinization of freshwater ecosystems as a result of human activities has markedly increased in recent years. Much attention is currently directed at evaluating the effects of increased salinity on freshwater biota. In the Central Appalachian region of the eastern United States, specific conductance from alkaline discharges associated with mountain top mining practices has been implicated in macroinvertebrate community declines in streams receiving coal mining discharges. Whole effluent toxicity testing of receiving stream water was used to test the hypothesis that mine discharges are toxic to laboratory test organisms and further, that toxicity is related to ionic concentrations as indicated by conductivity. Chronic toxicity testing using Ceriodaphnia dubia was conducted by contract laboratories at 72 sites with a total of 129 tests over a 3.5 year period. The database was evaluated to determine the ionic composition of mine effluent dominated streams and whether discharge constituents were related to toxicity in C. dubia. As expected, sulfate was found to be the dominant anion in streams receiving mining discharges with bicarbonate variable and sometimes a substantial component of the dissolved solids. Overall, the temporal variability in conductance was low at each site which would indicate fairly stable water quality conditions. Results of the toxicity tests show no relationship between conductance and survival of C. dubia in the mining influenced streams with the traditional toxicity test endpoints. However, consideration of the entire dataset revealed a significant inverse relationship between conductivity and neonate production. While conductivity explained very little of the high variability in the offspring production (r2 = 0.1304), the average numbers of offspring were consistently less than 20 neonates at the highest conductivities. PMID:27814378

Concentrations of selected trace inorganic constituents and synthetic organic compounds in the water-table aquifers in the Memphis area, Tennessee

USGS Publications Warehouse

McMaster, B.W.; Parks, William Scott

1988-01-01

Water quality samples for analysis of selected trace inorganic constituents and synthetic organic compounds were collected from 29 private or observation wells in alluvium and fluvial deposits of Quaternary and Tertiary Age. The alluvium and fluvial deposits are the water table aquifers in the Memphis area. In addition, nine wells were installed in Memphis Light, Gas and Water Division well fields so that samples could be collected and analyzed to characterize the quality of water in the fluvial deposits at these well fields. Samples from seven of these wells (two were dry) were analyzed for major constituents and properties of water as well as for selected trace inorganic constituents and synthetic organic compounds. Analyses of the water from most of the 36 wells sampled indicated ranges in concentration values for the trace inorganic constituents that agreed with those previously known, although some new maximum values were established. The analysis of water from four wells indicated that the water is or may be contaminated. Concentrations of barium (1,400 micrograms/L -- ug/L), strontium (1,100 ug/L), and arsenic (15 ug/L), along with specific conductance (1,420 microsiemens/centimeter--us/cm) were in water from one well in the alluvium. Low concentrations (0.02 to 0.04 ug/L) of the pesticides aldrin, DDT, endosulfan, and perthane were present in water from two wells in the fluvial deposits. Water from one of these wells also contained 1,1,1 trichloroethane (4.4 ug/L). Analysis of water from another well in the fluvial deposits indicated values for specific conductance (1,100 uS/cm), alkalinity (508 milligrams per liter -- mg/L -- as CaCO3), hardness (550 mg/L as CaCO3), chloride (65 mg/L), and barium (240 ug/L) that are high for water from the fluvial deposits. (USGS)

Physical-chemical examination of the N2O3-SO3-H2O system

NASA Technical Reports Server (NTRS)

Linstroem, C.; Malyska, G.

1977-01-01

It was found that when (NO)HSO4 is added to absolute H2SO4, specific conductivity rises sharply, possibly due to an increase in mutual interionic effects and viscosity as the (NO)HSO4 concentration rises. The addition of SO3 to the solution yielded a precipitate; a combination of analysis, IR spectroscopy and X-ray diffraction techniques indicated that this precipitate was (NO)HS2O7.

Statistical summaries of water-quality data for streams draining coal-mined areas, southeastern Kansas

USGS Publications Warehouse

Bevans, Hugh E.; Diaz, Arthur M.

1980-01-01

Summaries of descriptive statistics are compiled for 14 data-collection sites located on streams draining areas that have been shaft mined and strip mined for coal in Cherokee and Crawford Counties in southeastern Kansas. These summaries include water-quality data collected from October 1976 through April 1979. Regression equations relating specific conductance and instantaneous streamflow to concentrations of bicarbonate, sulfate, chloride, fluoride, calcium, magnesium, sodium, potassium, silica, and dissolved solids are presented.

Hydrogeochemical and stream sediment reconnaissance basic data for Brownsville-McAllen NTMS Quadrangles, Texas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1980-09-30

Results of a reconnaissance geochemical survey of the Brownsville-McAllen Quadrangles, Texas are reported. Field and laboratory data are presented for 427 groundwater and 171 stream sediment samples. Statistical and areal distributions of uranium and possible uranium-related variables are displayed. Pertinent geologic factors which may be of significance in evaluating the potential for uranium mineralization are briefly discussed. Groundwater data indicate the most promising area for potential uranium mineralization occurs in the northwestern section of the quadrangles (Jim Hogg, Starr, and Zapata Counties), where waters are derived from the Catahoula Formation. These groundwaters have high concentrations of uranium, uranium associated elements,more » and low values for specific conductance. Another area with high uranium concentrations is in the southeastern portion of the survey area (Hidalgo, Cameron, and Willacy Counties). Shallow wells <10 m (30 ft) are numerous in this area and high specific conductance values may indicate contamination from extensive fertilization. Stream sediment data for the survey does not indicate an area favorable for uranium mineralization. Anomalous acid soluble uranium values in the southeastern area (Hidalgo, Cameron, and Willacy Counties) can be attributed to phosphate fertilizer contamination. Four samples in the western part of the area (western Starr County) have anomalously high total uranium values and low acid soluble uranium values, indicating the uranium may be contained in resistate minerals.« less

Electrophysiological properties of computational human ventricular cell action potential models under acute ischemic conditions.

PubMed

Dutta, Sara; Mincholé, Ana; Quinn, T Alexander; Rodriguez, Blanca

2017-10-01

Acute myocardial ischemia is one of the main causes of sudden cardiac death. The mechanisms have been investigated primarily in experimental and computational studies using different animal species, but human studies remain scarce. In this study, we assess the ability of four human ventricular action potential models (ten Tusscher and Panfilov, 2006; Grandi et al., 2010; Carro et al., 2011; O'Hara et al., 2011) to simulate key electrophysiological consequences of acute myocardial ischemia in single cell and tissue simulations. We specifically focus on evaluating the effect of extracellular potassium concentration and activation of the ATP-sensitive inward-rectifying potassium current on action potential duration, post-repolarization refractoriness, and conduction velocity, as the most critical factors in determining reentry vulnerability during ischemia. Our results show that the Grandi and O'Hara models required modifications to reproduce expected ischemic changes, specifically modifying the intracellular potassium concentration in the Grandi model and the sodium current in the O'Hara model. With these modifications, the four human ventricular cell AP models analyzed in this study reproduce the electrophysiological alterations in repolarization, refractoriness, and conduction velocity caused by acute myocardial ischemia. However, quantitative differences are observed between the models and overall, the ten Tusscher and modified O'Hara models show closest agreement to experimental data. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Toxicity of vanadium in soil on soybean at different growth stages.

PubMed

Yang, Jinyan; Wang, Mei; Jia, Yanbo; Gou, Min; Zeyer, Josef

2017-12-01

Vanadium(V) is present in trace amounts in most plants and widely distributed in soils. However, the environmental toxicity of V compound in soils is controversial. A greenhouse study with soybean from germination to bean production under exposure to pentavalent V [V(V)] was conducted to elucidate the interaction of plants and V fractions in soils and to evaluate the toxicity of V at different plant growth stages. Soybean growth has no effect on non-specific-bond and specific-bond fractions of V in soils, but V fractionation occurred in more extraction-resistant phases at high V concentrations. High concentrations of V(V) postponed the germination and growth of the soybeans. Bean production was less than half of that of the control at 500 mg kg -1 spiked V(V). For the 0 mg kg -1 spiked V(V) treated plants, the root was not the main location where V was retained. Vanadium in the soils at ≤ 250 mg kg -1 did not significantly affect the V concentration in the shoot and leaf of soybeans. With the increase in V concentration in soil, V concentrations in roots increased, whereas those in beans and pods decreased. From vegetative growth to the reproductive growth, the soybeans adsorbed more V and accumulated more V in the roots, with <20% transported to the aboveground parts. Hence, the analysis of V concentration in vegetative tissues or beans may not be a useful indicator for V pollution in soil. Meanwhile, the ratio of V concentration in cell wall to the total V concentration in the root increased with the increase in V(V) concentration in soils. Our results revealed that high concentrations of V inhibited soybean germination and biomass production. However, plants may produce self-defense systems to endure V toxicity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Complex conductivity response to silver nanoparticles in partially saturated sand columns

NASA Astrophysics Data System (ADS)

Abdel Aal, Gamal; Atekwana, Estella A.; Werkema, D. Dale

2017-02-01

The increase in the use of nanoscale materials in consumer products has resulted in a growing concern of their potential hazard to ecosystems and public health from their accidental or intentional introduction to the environment. Key environmental, health, and safety research needs include knowledge and methods for their detection, characterization, fate, and transport. Specifically, techniques available for the direct detection and quantification of their fate and transport in the environment are limited. Their small size, high surface area to volume ratio, interfacial, and electrical properties make metallic nanoparticles, such as silver nanoparticles, good targets for detection using electrical geophysical techniques. Here we measured the complex conductivity response to silver nanoparticles in sand columns under varying moisture conditions (0-30%), nanoparticle concentrations (0-10 mg/g), lithology (presence of clay), pore water salinity (0.0275 and 0.1000 S/m), and particle size (35, 90-210 and 1500-2500 nm). Based on the Cole-Cole relaxation models we obtained the chargeability and the time constant. We demonstrate that complex conductivity can detect silver nanoparticles in porous media with the response enhanced by higher concentrations of silver nanoparticles, moisture content, ionic strength, clay content and particle diameter. Quantification of the volumetric silver nanoparticles content in the porous media can also be obtained from complex conductivity parameters based on the strong power law relationships.

Determination of the molecular complexation constant between alprostadil and alpha-cyclodextrin by conductometry: implications for a freeze-dried formulation.

PubMed

Sheehy, Philip M; Ramstad, Tore

2005-10-04

The binding constant between alprostadil (PGE1) and alpha-cyclodextrin (alpha-CD) was determined at four temperatures using conductance measurements. Alpha-cyclodextrin is an excipient material in Caverject dual chamber syringe (DCS) that was added to enhance stability. The binding constant was used to calculate the amount of PGE1 free upon reconstitution and injection, since only the free drug is clinically active. The conductivity measurement is based on a decrease in specific conductance as alprostadil is titrated with alpha-CD. The change in conductivity was plotted versus free ligand concentration (alpha-CD) to generate a binding curve. As the value of the binding constant proved to be dependent on substrate concentration, it is really a pseudo binding constant. A value of 742+/-60 M(-1) was obtained for a 0.5 mM solution of alprostadil at 27 degrees C and a value of 550+/-52 M(-1) at 37 degrees C. These results compare favorably to values previously obtained by NMR and capillary electrophoresis. Calculation of the fraction PGE1 free upon reconstitution and injection show it to approach the desired outcome of one. Hence, the amount of drug delivered by Caverject DCS is nominally equivalent to that delivered by Caverject S. Po., a predecessor product that contains no alpha-cyclodextrin.

Minimizing damage to a propped fracture by controlled flowback procedures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robinson, B.M.; Holditch, S.A.; Whitehead, W.S.

1988-06-01

Severe fracture-conductivity damage can result from proppant crushing and/or proppant flowback into the wellbore. Such damage is often concentrated near the wellbore and can directly affect postfracture performance. Most of the time severe fracture-conductivity damage can be minimized by choosing the correct type of proppant for a particular well. In many cases, however, this is not enough. To minimize excessive crushing or to prevent proppant flowback, it is also necessary to control carefully the flowback of the well after the treatment. Specific procedures can be followed to minimize severe fracture-conductivity damage. These procedures involve controlling the rates at which loadmore » fluids are recovered and maximizing backpressure against the formation. These procedures require much more time and effort than is normally spent on postfracture cleanup; however, the efforts could result in better performance.« less

Novel Quantification of Sediment Concentration in Turbidity Currents Through in-situ Measurements of Conductivity and Temperature

NASA Astrophysics Data System (ADS)

Xu, J.; Wang, Z.; Gwiazda, R.; Paull, C. K.; Talling, P.; Parsons, D. R.; Maier, K. L.; Simmons, S.; Cartigny, M.

2017-12-01

During a large turbidity current event observed by seven moorings placed along Monterey Canyon, offshore central California, in the axial channel between 300 and 1900 meters water depth, a conductivity/temperature sensor placed 11 meters above canyon floor on the mooring at 1500 meters water depth recorded a rapid decrease of conductivity and increase of temperature during the passage of a large turbidity current. The conductivity decline is unlikely caused by fresh water input owing to lack of precipitation in the region prior to the event. We investigated the mechanisms of turbidity currents' high sediment concentration reducing the measured conductivity. By conducting a series of laboratory experiments with a range of different concentrations, grain size, and water temperature combinations, we quantified a relationship between reduced conductivity and the elevated sediment concentration. This relationship can be used for estimating the very high sediment concentrations in a turbidity current with a condition of assuming constant salinity of the ambient seawater. The empirical relationship was then applied to the in-situ time-series of temperature and conductivity measured during this turbidity current. The highest sediment concentration, in the head of the flow, reached nearly 400 g/L (volume concentration 17%). Such a high value, which has yet been reported in literature for an oceanic turbidity current, will have significant implications for the dynamics and deposits of such flows.

Geohydrology and water quality of Kalamazoo County, Michigan, 1986-88

USGS Publications Warehouse

Rheaume, S.J.

1990-01-01

Thick, glacial sand and gravel deposits provide most ground-water supplies in Kalamazoo County. These deposits range in thickness from 50 to about 600 feet in areas that overlie buried bedrock valleys. Most domestic wells completed at depths of less than 75 feet in the sands and gravels yield adequate water supplies. Most industry, public supply, and irrigation wells completed at depths of 100 to 200 feet yield 1,000 gallons per minute or more. The outwash plains include the most productive of the glacial aquifers in the county. The Coldwater Shale of Mississippian age, which underlies the glacial deposits in most of the county, usually yields only small amounts of largely mineralized water. Ground-water levels in Kalamazoo County reflect short- and long-term changes in precipitation and local pumpage. Ground-water levels increase in the spring and decline in the fall. Ground-water recharge rates, for different geologic settings, were estimated from ground-water runoff to the streams. Recharge rates ranged from 10.86 to 5.87 inches per year. A countywide-average ground-water recharge rate is estimated to be 9.32 inches per year. Chemical quality of precipitation and dry fallout at two locations in Kalamazoo County were similar to that of other areas in the State. Total deposition of dissolved sulfate is 30.7 pounds per acre per year, of total nitrogen is 13.2 pounds per acre per year, and of total phosphorus is 0.3 pounds per acre per year. Rainfall and snow data indicated that the pH of precipitation is inversely proportional to its specific conductance. Water of streams and rivers of Kalamazoo County is predominately of the calcium bicarbonate type, although dissolved sulfate concentrations are slightly larger in streams in the southeastern and northwestern parts of the county. The water in most streams is hard to very hard. Concentrations of dissolved chloride in streams draining urban-industrial areas are slightly larger than at other locations. Concentrations of total nitrogen and total phosphorus in streams are directly proportional to streamflow. Except for elevated concentrations of iron, none of the trace elements in streams exceeded maximum contaminant levels for drinking water established by the U.S. Environmental Protection Agency. Pesticides were detected in some streams. Ground water in the surficial aquifers is of the calcium bicarbonate type, although sodium, sulfate, and chloride ions predominate at some locations. Specific conductance and hardness and concentrations of total dissolved-solids slightly exceed statewide averages. Concentrations of dissolved sodium and dissolved chloride in 6 wells were greater than most natural ground waters in the State, indicating possible contamination from road salts. Water samples from 6 of the 46 wells sampled contained concentrations of total nitrate as nitrogen greater than 10.0 milligrams per liter. Elevated concentrations of total nitrate as nitrogen in water from wells in rural-agricultural areas probably are related to fertilizer applications. Results of partial chemical analyses by the Michigan Department of Public Health indicates specific conductance, and concentrations of hardness, dissolved fluoride, and total iron are fairly uniform throughout the county. Concentrations of dissolved sodium, dissolved chloride, and total nitrate as nitrogen differed among townships. Pesticides were detected in water from only one well. Water from five wells contained volatile organics. A map of susceptibility of ground water to contamination in Kalamazoo County was developed using a system created by the U.S. Environmental Protection Agency. Seven geohydrologic factors that affect and control ground-water movement are mapped and composited onto a countywide map. All seven factors have some effect on countywide susceptibility, but the most important factors are depth to water and composition of the materials above the aquifer.

Drinking water insecurity: water quality and access in coastal south-western Bangladesh.

PubMed

Benneyworth, Laura; Gilligan, Jonathan; Ayers, John C; Goodbred, Steven; George, Gregory; Carrico, Amanda; Karim, Md Rezaul; Akter, Farjana; Fry, David; Donato, Katherine; Piya, Bhumika

2016-01-01

National drinking water assessments for Bangladesh do not reflect local variability, or temporal differences. This paper reports on the findings of an interdisciplinary investigation of drinking water insecurity in a rural coastal south-western Bangladesh. Drinking water quality is assessed by comparison of locally measured concentrations to national levels and water quality criteria; resident's access to potable water and their perceptions are based on local social surveys. Residents in the study area use groundwater far less than the national average; salinity and local rainwater scarcity necessitates the use of multiple water sources throughout the year. Groundwater concentrations of arsenic and specific conductivity (SpC) were greater than surface water (pond) concentrations; there was no statistically significant seasonal difference in mean concentrations in groundwater, but there was for ponds, with arsenic higher in the dry season. Average arsenic concentrations in local water drinking were 2-4 times times the national average. All of the local groundwater samples exceeded the Bangladesh guidance for SpC, although the majority of residents surveyed did not perceive their water as having a 'bad' or 'salty' taste.

Mercury concentrations in Northwest Atlantic winter-caught, male spiny dogfish (Squalus acanthias): A geographic mercury comparison and risk-reward framework for human consumption.

PubMed

St Gelais, Adam T; Costa-Pierce, Barry A

2016-01-15

Mercury (Hg) contamination testing was conducted on winter-caught male spiny dogfish (Squalus acanthias) in southern New England and results compared to available data on Hg concentrations for this species. A limited risk-reward assessment for EPA (eicosapentanoic acid) and DHA (docosahexanoic acid) lipid concentrations of spiny dogfish was completed in comparison with other commonly consumed marine fish. Mean Hg concentrations were 0.19 ppm (±0.30) wet weight. In comparison, mean Hg concentrations in S. acanthias varied geographically ranging from 0.05 ppm (Celtic Sea) to 2.07 ppm (Crete, Mediterranean Sea). A risk-reward assessment for Hg and DHA+EPA placed S. acanthias in both "low-risk, high-reward" and "high-risk, high-reward" categories for consumption dependent on locations of the catch. Our results are limited and are not intended as consumption advisories but serve to illustrate the need for making more nuanced, geo-specific, consumption guidance for spiny dogfish that is inclusive of seafood traceability and nutritional benefits. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Investigating nitrate dynamics in a fine-textured soil affected by feedlot effluents.

PubMed

Veizaga, E A; Rodríguez, L; Ocampo, C J

2016-10-01

Feedlots concentrate large volumes of manure and effluents that contain high concentrations of nitrate, among other constituents. If not managed properly, pen surfaces run-off and lagoons overflows may spread those effluents to surrounding land, infiltrating into the soil. Soil nitrate mobilization and distribution are of great concern due to its potential migration towards groundwater resources. This work aimed at evaluating the migration of nitrate originated on feedlots effluents in a fine-textured soil under field conditions. Soil water constituents were measured during a three-year period at three distinct locations adjacent to feedlot retention lagoons representing different degrees of exposure to water flow and manure accumulation. A simple statistical analysis was undertaken to identify patterns of observed nitrate and chloride concentrations and electrical conductivity and their differences with depth. HYDRUS-1D was used to simulate water flow and solute transport of Cl - , NO 4 + N, NO 3 - N and electrical conductivity to complement field data interpretation. Results indicated that patterns of NO 3 - N concentrations were not only notoriously different from electrical conductivity and Cl - but also ranges and distribution with depth differed among locations. A combination of dilution, transport, reactions such as nitrification/denitrification and vegetation water and solute uptake took place at each plots denoting the complexity of soil-solution behavior under extreme polluting conditions. Simulations using the concept of single porosity-mobile/immobile water (SP-MIM) managed structural controls and correctly simulated - all species concentrations under field data constrains. The opposite was true for the other two locations experiencing near-saturation conditions, absence of vegetation and frequent manure accumulation and runoff from feedlot lagoons. Although the results are site specific, findings are relevant to advance the understanding of NO 3 - N dynamics resulting from FL operations under heavy soils. Copyright © 2016 Elsevier B.V. All rights reserved.

Streamflow, water quality and constituent loads and yields, Scituate Reservoir drainage area, Rhode Island, water year 2014

USGS Publications Warehouse

Smith, Kirk P.

2016-05-03

Streamflow and concentrations of sodium and chloride estimated from records of specific conductance were used to calculate loads of sodium and chloride during water year (WY) 2014 (October 1, 2013, through September 30, 2014) for tributaries to the Scituate Reservoir, Rhode Island. Streamflow and water-quality data used in the study were collected by the U.S. Geological Survey and the Providence Water Supply Board in the cooperative study. Streamflow was measured or estimated by the U.S. Geological Survey following standard methods at 23 streamgages; 14 of these streamgages are equipped with instrumentation capable of continuously monitoring water level, specific conductance, and water temperature. Water-quality samples were collected at 37 sampling stations by the Providence Water Supply Board and at 14 continuous-record streamgages by the U.S. Geological Survey during WY 2014 as part of a long-term sampling program; all stations are in the Scituate Reservoir drainage area. Water-quality data collected by the Providence Water Supply Board are summarized by using values of central tendency and are used, in combination with measured (or estimated) streamflows, to calculate loads and yields (loads per unit area) of selected water-quality constituents for WY 2014.The largest tributary to the reservoir (the Ponaganset River, which was monitored by the U.S. Geological Survey) contributed a mean streamflow of 23 cubic feet per second to the reservoir during WY 2014. For the same time period, annual mean streamflows measured (or estimated) for the other monitoring stations in this study ranged from about 0.35 to about 14 cubic feet per second. Together, tributaries (equipped with instrumentation capable of continuously monitoring specific conductance) transported about 1,200,000 kilograms of sodium and 2,100,000 kilograms of chloride to the Scituate Reservoir during WY 2014; sodium and chloride yields for the tributaries ranged from 7,700 to 45,000 kilograms per year per square mile and from 12,000 to 75,000 kilograms per year per square mile, respectively.At the stations where water-quality samples were collected by the Providence Water Supply Board, the median of the median chloride concentrations was 24 milligrams per liter, median nitrite concentration was 0.002 milligrams per liter as nitrogen (N), median nitrate concentration was 0.01 milligrams per liter as N, median orthophosphate concentration was 0.07 milligrams per liter as phosphate, and median concentrations of total coliform bacteria and Escherichia coli were 320 and 20 colony forming units per 100 milliliters, respectively. The medians of the median daily loads (and yields) of chloride, nitrite, nitrate, orthophosphate, and total coliform and Escherichia coli bacteria were 62 kilograms per day (42 kilograms per day per square mile), 19 grams per day (6.1 grams per day per square mile), 79 grams per day (36 grams per day per square mile), 380 grams per day (150 grams per day per square mile), 13,000 million colony forming units per day (8,300 million colony forming units per day per square mile), and 1,000 million colony forming units per day (470 million colony forming units per day per square mile), respectively.

Streamflow, water quality, and constituent loads and yields, Scituate Reservoir drainage area, Rhode Island, water year 2012

USGS Publications Warehouse

Smith, Kirk P.

2014-01-01

Streamflow and concentrations of sodium and chloride estimated from records of specific conductance were used to calculate loads of sodium and chloride during water year (WY) 2012 (October 1, 2011, through September 30, 2012), for tributaries to the Scituate Reservoir, Rhode Island. Streamflow and water-quality data used in the study were collected by the U.S. Geological Survey (USGS) or the Providence Water Supply Board (PWSB). Streamflow was measured or estimated by the USGS following standard methods at 23 streamgages; 14 of these streamgages were equipped with instrumentation capable of continuously monitoring water level, specific conductance, and water temperature. Water-quality samples were collected at 37 sampling stations by the PWSB and at 14 continuous-record streamgages by the USGS during WY 2012 as part of a long-term sampling program; all stations were in the Scituate Reservoir drainage area. Water-quality data collected by the PWSB were summarized by using values of central tendency and used, in combination with measured (or estimated) streamflows, to calculate loads and yields (loads per unit area) of selected water-quality constituents for WY 2012. The largest tributary to the reservoir (the Ponaganset River, which was monitored by the USGS) contributed a mean streamflow of about 26 cubic feet per second (ft3/s) to the reservoir during WY 2012. For the same time period, annual mean1 streamflows measured (or estimated) for the other monitoring stations in this study ranged from about 0.40 to about 17 ft3/s. Together, tributaries (equipped with instrumentation capable of continuously monitoring specific conductance) transported about 1,100,000 kilograms (kg) of sodium and 1,900,000 kg of chloride to the Scituate Reservoir during WY 2012; sodium and chloride yields for the tributaries ranged from 8,700 to 51,000 kilograms per square mile (kg/mi2) and from 14,000 to 87,000 kg/mi2, respectively. At the stations where water-quality samples were collected by the PWSB, the median of the median chloride concentrations was 19 milligrams per liter (mg/L), median nitrite concentration was 0.002 mg/L as nitrogen (N), median nitrate concentration was less than 0.01 mg/L as N, median orthophosphate concentration was 0.06 mg/L as phosphorus, and median concentrations of total coliform and Escherichia coli (E. coli) bacteria were 43 and 16 colony forming units per 100 milliliters (CFU/100mL), respectively. The medians of the median daily loads (and yields) of chloride, nitrite, nitrate, orthophosphate, and total coliform and E. coli bacteria were 200 kilograms per day (kg/d) (71 kilograms per day per square mile (kg/d/mi2)); 15 grams per day (g/d) (5.4 grams per day per square mile (g/d/mi2)); 100 g/d (38 g/d/mi2); 500 g/d (260 g/d/mi2); 4,300 million colony forming units per day (CFUx106/d) (1,500 CFUx106/d/mi2); and 1,000 CFUx106/d (360 CFUx106/d/mi2), respectively.

Streamflow, water quality, and constituent loads and yields, Scituate Reservoir drainage area, Rhode Island, water year 2011

USGS Publications Warehouse

Smith, Kirk P.

2013-01-01

Streamflow and concentrations of sodium and chloride estimated from records of specific conductance were used to calculate loads of sodium and chloride during water year (WY) 2011 (October 1, 2010, to September 30, 2011), for tributaries to the Scituate Reservoir, Rhode Island. Streamflow and water-quality data used in the study were collected by the U.S. Geological Survey (USGS) or the Providence Water Supply Board (PWSB). Streamflow was measured or estimated by the USGS following standard methods at 23 streamgages; 14 of these streamgages were also equipped with instrumentation capable of continuously monitoring water level, specific conductance, and water temperature. Water-quality samples also were collected at 37 sampling stations by the PWSB and at 14 continuous-record streamgages by the USGS during WY 2011 as part of a long-term sampling program; all stations were in the Scituate Reservoir drainage area. Water-quality data collected by PWSB are summarized by using values of central tendency and are used, in combination with measured (or estimated) streamflows, to calculate loads and yields (loads per unit area) of selected water-quality constituents for WY 2011. The largest tributary to the reservoir (the Ponaganset River, which was monitored by the USGS) contributed a mean streamflow of about 37 cubic feet per second (ft3/s) to the reservoir during WY 2011. For the same time period, annual mean1 streamflows measured (or estimated) for the other monitoring stations in this study ranged from about 0.5 to about 21 ft3/s. Together, tributaries (equipped with instrumentation capable of continuously monitoring specific conductance) transported about 1,600,000 kg (kilograms) of sodium and 2,600,000 kg of chloride to the Scituate Reservoir during WY 2011; sodium and chloride yields for the tributaries ranged from 9,800 to 53,000 kilograms per square mile (kg/mi2) and from 15,000 to 90,000 kg/mi2, respectively. At the stations where water-quality samples were collected by the PWSB, the median of the median chloride concentrations was 20.0 milligrams per liter (mg/L), median nitrite concentration was 0.002 mg/L as nitrogen (N), median nitrate concentration was 0.01 mg/L as N, median orthophosphate concentration was 0.07 mg/L as phosphorus, and median concentrations of total coliform and Escherichia coli (E. coli) bacteria were 33 and 23 colony forming units per 100 milliliters (CFU/100mL), respectively. The medians of the median daily loads (and yields) of chloride, nitrite, nitrate, orthophosphate, and total coliform and E. coli bacteria were 230 kilograms per day (kg/d) (80 kilograms per day per square mile (kg/d/mi2)); 10 grams per day (g/d) (6.3 grams per day per square mile (g/d/mi2)); 110 g/d (29 g/d/mi2); 610 g/d (270 g/d/mi2); 4,600 million colony forming units per day (CFUx106/d) (2,500 CFUx106/d/mi2); and 1,800 CFUx106/d (810 CFUx106/d/mi2), respectively.

Streamflow, water quality, and constituent loads and yields, Scituate Reservoir drainage area, Rhode Island, water year 2003

USGS Publications Warehouse

Breault, Robert F.; Campbell, Jean P.

2010-01-01

Streamflow and water-quality data were collected by the U.S. Geological Survey (USGS) or the Providence Water Supply Board, Rhode Island's largest drinking-water supplier. Streamflow was measured or estimated by the USGS following standard methods at 23 streamgage stations; 10 of these stations were also equipped with instrumentation capable of continuously monitoring specific conductance. Streamflow and concentrations of sodium and chloride estimated from records of specific conductance were used to calculate instantaneous (15-minute) loads of sodium and chloride during water year (WY) 2003 (October 1, 2002, to September 30, 2003). Water-quality samples were also collected at 37 sampling stations in the Scituate Reservoir drainage area by the Providence Water Supply Board during WY 2003 as part of a long-term sampling program. Water-quality data are summarized by using values of central tendency and are used, in combination with measured (or estimated) streamflows, to calculate loads and yields (loads per unit area) of selected water-quality constituents for WY 2003. The largest tributary to the reservoir (the Ponaganset River, which was monitored by the USGS) contributed about 31 cubic feet per second (ft3/s) to the reservoir during WY 2003. For the same time period, annual mean streamflows1 measured (or estimated) for the other monitoring stations in this study ranged from about 0.44 to 20 ft3/s. Together, tributary streams (equipped with instrumentation capable of continuously monitoring specific conductance) transported about 1,200,000 kilograms (kg) of sodium and 1,900,000 kg of chloride to the Scituate Reservoir during WY 2003; sodium and chloride yields for the tributaries ranged from 10,000 to 61,000 kilograms per square mile (kg/mi2) and from 15,000 to 100,000 kg/mi2, respectively. At the stations where water-quality samples were collected by the Providence Water Supply Board, the median of the median chloride concentrations was 21.3 milligrams per liter (mg/L), median nitrite concentration was 0.002 mg/L as N, median nitrate concentration was 0.02 mg/L as N, median orthophosphate concentration was 0.06 mg/L as P, and median concentrations of total coliform and Escherichia coli (E. coli) bacteria were 38 and 9 CFU/100 mL (colony forming units per 100 milliliters), respectively. The medians of the median daily loads (and yields) of chloride, nitrite, nitrate, orthophosphate, and total coliform and E. coli bacteria were 140 kg/d (67 kg/d/mi2), 15 g/d (6.5 g/d/mi2), 140 g/d (62 g/d/mi2), 340 g/d (180 g/d/mi2), and 2,200 million colony forming units per day (CFU x 106/d) (1,200 CFU x 106/d/mi2) and 940 CFU x 106/d (490 CFU x 106/d/mi2), respectively. 1The arithmetic mean of the individual daily mean discharges for the year noted or for the designated period.

Streamflow, water quality, and constituent loads and yields, Scituate Reservoir drainage area, Rhode Island, water year 2009

USGS Publications Warehouse

Breault, Robert F.; Smith, Kirk P.

2010-01-01

Streamflow and water-quality data were collected by the U.S. Geological Survey (USGS) or the Providence Water Supply Board (PWSB), Rhode Island's largest drinking-water supplier. Streamflow was measured or estimated by the USGS following standard methods at 23 streamgage stations; 13 of these stations were also equipped with instrumentation capable of continuously monitoring specific conductance and water temperature. Streamflow and concentrations of sodium and chloride estimated from records of specific conductance were used to calculate loads of sodium and chloride during water year (WY) 2009 (October 1, 2008, to September 30, 2009). Water-quality samples also were collected at 37 sampling stations by the PWSB and at 14 monitoring stations by the USGS during WY 2009 as part of a long-term sampling program; all stations are in the Scituate Reservoir drainage area. Water-quality data collected by PWSB are summarized by using values of central tendency and are used, in combination with measured (or estimated) streamflows, to calculate loads and yields (loads per unit area) of selected water-quality constituents for WY 2009. The largest tributary to the reservoir (the Ponaganset River, which was monitored by the USGS) contributed a mean streamflow of about 27 cubic feet per second (ft3/s) to the reservoir during WY 2009. For the same time period, annual mean1 streamflows measured (or estimated) for the other monitoring stations in this study ranged from about 0.50 to 17 ft3/s. Together, tributary streams (equipped with instrumentation capable of continuously monitoring specific conductance) transported about 1,400,000 kilograms (kg) of sodium and 2,200,000 kg of chloride to the Scituate Reservoir during WY 2009; sodium and chloride yields for the tributaries ranged from 10,000 to 64,000 kilograms per square mile (kg/mi2) and from 15,000 to 110,000 kg/mi2, respectively. At the stations where water-quality samples were collected by the PWSB, the median of the median chloride concentrations was 21.7 milligrams per liter (mg/L), median nitrite concentration was 0.001 mg/L as N, median nitrate concentration was 0.02 mg/L as N, median orthophosphate concentration was 0.09 mg/L as P, and median concentrations of total coliform and Escherichia coli (E. coli) bacteria were 61 and 16 colony forming units per 100 milliliters (CFU/100 mL), respectively. The medians of the median daily loads (and yields) of chloride, nitrite, nitrate, orthophosphate, and total coliform and E. coli bacteria were 190 kg/d (61 kg/d/mi2), 12 g/d (4.5 g/d/mi2), 93 g/d (32 g/d/mi2), 420 g/d (290 g/d/mi2), 6,200 million colony forming units per day (CFU?106/d) (2,600 CFU?106/d/mi2), and 1,100 CFU?106/d (340 CFU?106/d/mi2), respectively. 1The arithmetic mean of the individual daily mean discharges for the year noted or for the designated period.

Streamflow, water quality, and constituent loads and yields, Scituate Reservoir drainage area, Rhode Island, water year 2004

USGS Publications Warehouse

Breault, Robert F.; Campbell, Jean P.

2010-01-01

Streamflow and water-quality data were collected by the U.S. Geological Survey (USGS) or the Providence Water Supply Board, Rhode Island's largest drinking-water supplier. Streamflow was measured or estimated by the USGS following standard methods at 23 streamgage stations; 10 of these stations were also equipped with instrumentation capable of continuously monitoring specific conductance. Streamflow and concentrations of sodium and chloride estimated from records of specific conductance were used to calculate instantaneous (15-minute) loads of sodium and chloride during water year (WY) 2004 (October 1, 2003, to September 30, 2004). Water-quality samples were also collected at 37 sampling stations in the Scituate Reservoir drainage area by the Providence Water Supply Board during WY 2004 as part of a long-term sampling program. Water-quality data are summarized by using values of central tendency and are used, in combination with measured (or estimated) streamflows, to calculate loads and yields (loads per unit area) of selected water-quality constituents for WY 2004. The largest tributary to the reservoir (the Ponaganset River, which was monitored by the USGS) contributed about 27 cubic feet per second (ft3/s) to the reservoir during WY 2004. For the same time period, annual mean1 streamflows measured (or estimated) for the other monitoring stations in this study ranged from about 0.42 to 19 ft3/s. Together, tributary streams (equipped with instrumentation capable of continuously monitoring specific conductance) transported about 1,100,000 kilograms (kg) of sodium and 1,700,000 kg of chloride to the Scituate Reservoir during WY 2004; sodium and chloride yields for the tributaries ranged from 12,000 to 61,000 kilograms per square mile (kg/mi2) and from 17,000 to 100,000 kg/mi2, respectively. At the stations where water-quality samples were collected by the Providence Water Supply Board, the median of the median chloride concentrations was 24.8 milligrams per liter (mg/L), median nitrite concentration was 0.001 mg/L as N, median nitrate concentration was 0.03 mg/L as N, median orthophosphate concentration was 0.07 mg/L as P, and median concentrations of total coliform and Escherichia coli (E. coli) bacteria were 33 and 23 colony forming units per 100 milliliters (CFU/100 mL), respectively. The medians of the median daily loads (and yields) of chloride, nitrite, nitrate, orthophosphate, and total coliform and E. coli bacteria were 160 kg/d (81 kg/d/mi2), 9.1 g/d (5.2 g/d/mi2), 280 g/d (110 g/d/mi2), 760 g/d (340 g/d/mi2), and 4,700 million colony forming units per day (CFU x 106/d) (1,700 CFU x 106/d/mi2) and 1,900 CFU x 106/d (520 CFU x 106/d/mi2), respectively. 1The arithmetic mean of the individual daily mean discharges for the year noted or for the designated period

Associations between short-term exposure to ambient sulfur dioxide and increased cause-specific mortality in 272 Chinese cities.

PubMed

Wang, Lijun; Liu, Cong; Meng, Xia; Niu, Yue; Lin, Zhijing; Liu, Yunning; Liu, Jiangmei; Qi, Jinlei; You, Jinling; Tse, Lap Ah; Chen, Jianmin; Zhou, Maigeng; Chen, Renjie; Yin, Peng; Kan, Haidong

2018-04-28

Ambient sulfur dioxide (SO 2 ) remains a major air pollutant in developing countries, but epidemiological evidence about its health effects was not abundant and inconsistent. To evaluate the associations between short-term exposure to SO 2 and cause-specific mortality in China. We conducted a nationwide time-series analysis in 272 major Chinese cities (2013-2015). We used the over-dispersed generalized linear model together with the Bayesian hierarchical model to analyze the data. Two-pollutant models were fitted to test the robustness of the associations. We conducted stratification analyses to examine potential effect modifications by age, sex and educational level. On average, the annual-mean SO 2 concentrations was 29.8 μg/m 3 in 272 cities. We observed positive and associations of SO 2 with total and cardiorespiratory mortality. A 10 μg/m 3 increase in two-day average concentrations of SO 2 was associated with increments of 0.59% in mortality from total non-accidental causes, 0.70% from total cardiovascular diseases, 0.55% from total respiratory diseases, 0.64% from hypertension disease, 0.65% from coronary heart disease, 0.58% from stroke, and 0.69% from chronic obstructive pulmonary disease. In two-pollutant models, there were no significant differences between single-pollutant model and two-pollutant model estimates with fine particulate matter, carbon monoxide and ozone, but the estimates decreased substantially after adjusting for nitrogen dioxide, especially in South China. The associations were stronger in warmer cities, in older people and in less-educated subgroups. This nationwide study demonstrated associations of daily SO 2 concentrations with increased total and cardiorespiratory mortality, but the associations might not be independent from NO 2 . Copyright © 2018 Elsevier Ltd. All rights reserved.

Hydrologic Data Summary for the Northeast Creek/Fresh Meadow Estuary, Acadia National Park, Maine, 2000-2001

USGS Publications Warehouse

Caldwell, James M.; Culbertson, Charles W.

2007-01-01

The U.S. Geological Survey, in cooperation with the National Park Service, collected data in Northeast Creek estuary, Mt. Desert Island, Maine, to establish baseline water-quality conditions including estuarine nutrient concentrations. Five sampling sites in Northeast Creek were established and monitored continuously for temperature and specific conductance during May to November, 2000 and 2001. Stream stage, which was affected by ocean tidal dynamics, was recorded at the most downstream site and at one upstream site. Discrete water samples for nutrient concentrations were collected biweekly during May to November, 2000 and 2001, at the five sampling sites, and an additional site seaward of the estuary mouth. Results indicated that the salinity regime of Northeast Creek estuary is dynamic and highly regulated by strong seasonal variations in freshwater runoff, as well as limited seawater exchange caused by a constriction at the bridge, at the downstream end of the estuary. Oligohaline conditions (0.5-5 practical salinity units) occasionally extend to the estuary mouth. During other periods oligohaline and mesohaline (5-20 practical salinity units) conditions exist in some areas of the estuary; polyhaline/marine (20-35 practical salinity units) conditions occasionally exist near the mouth. A saltwater wedge in the bottom water, due to density stratification, was observed to migrate upstream as fresh surface-water inputs diminished during the onset of summer low-flow conditions. Although specific conductance ranged widely at most sites because of tidal influences, other water-quality constituents, including nutrient and chlorophyll-a concentrations, exhibited seasonal distribution patterns in which maximum levels generally occurred in early to mid-summer and again in the fall over both field seasons.

Tile drainage as karst: Conduit flow and diffuse flow in a tile-drained watershed

USGS Publications Warehouse

Schilling, K.E.; Helmers, M.

2008-01-01

The similarity of tiled-drained watersheds to karst drainage basins can be used to improve understanding of watershed-scale nutrient losses from subsurface tile drainage networks. In this study, short-term variations in discharge and chemistry were examined from a tile outlet collecting subsurface tile flow from a 963 ha agricultural watershed. Study objectives were to apply analytical techniques from karst springs to tile discharge to evaluate water sources and estimate the loads of agricultural pollutants discharged from the tile with conduit, intermediate and diffuse flow regimes. A two-member mixing model using nitrate, chloride and specific conductance was used to distinguish rainwater versus groundwater inputs. Results indicated that groundwater comprised 75% of the discharge for a three-day storm period and rainwater was primarily concentrated during the hydrograph peak. A contrasting pattern of solute concentrations and export loads was observed in tile flow. During base flow periods, tile flow consisted of diffuse flow from groundwater sources and contained elevated levels of nitrate, chloride and specific conductance. During storm events, suspended solids and pollutants adhered to soil surfaces (phosphorus, ammonium and organic nitrogen) were concentrated and discharged during the rapid, conduit flow portion of the hydrograph. During a three-day period, conduit flow occurred for 5.6% of the time but accounted for 16.5% of the total flow. Nitrate and chloride were delivered primarily with diffuse flow (more than 70%), whereas 80-94% of total suspended sediment, phosphorus and ammonium were exported with conduit and intermediate flow regimes. Understanding the water sources contributing to tile drainage and the manner by which pollutant discharge occurs from these systems (conduit, intermediate or diffuse flow) may be useful for designing, implementing and evaluating non-point source reduction strategies in tile-drained landscapes. ?? 2007 Elsevier B.V. All rights reserved.

Simulant Development for LAWPS Testing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Russell, Renee L.; Schonewill, Philip P.; Burns, Carolyn A.

2017-05-23

This report describes simulant development work that was conducted to support the technology maturation of the LAWPS facility. Desired simulant physical properties (density, viscosity, solids concentration, solid particle size), sodium concentrations, and general anion identifications were provided by WRPS. The simulant recipes, particularly a “nominal” 5.6M Na simulant, are intended to be tested at several scales, ranging from bench-scale (500 mL) to full-scale. Each simulant formulation was selected to be chemically representative of the waste streams anticipated to be fed to the LAWPS system, and used the current version of the LAWPS waste specification as a formulation basis. After simulantmore » development iterations, four simulants of varying sodium concentration (5.6M, 6.0M, 4.0M, and 8.0M) were prepared and characterized. The formulation basis, development testing, and final simulant recipes and characterization data for these four simulants are presented in this report.« less

Influence of chemical disorder on energy dissipation and defect evolution in concentrated solid solution alloys

PubMed Central

Zhang, Yanwen; Stocks, G. Malcolm; Jin, Ke; Lu, Chenyang; Bei, Hongbin; Sales, Brian C.; Wang, Lumin; Béland, Laurent K.; Stoller, Roger E.; Samolyuk, German D.; Caro, Magdalena; Caro, Alfredo; Weber, William J.

2015-01-01

A grand challenge in materials research is to understand complex electronic correlation and non-equilibrium atomic interactions, and how such intrinsic properties and dynamic processes affect energy transfer and defect evolution in irradiated materials. Here we report that chemical disorder, with an increasing number of principal elements and/or altered concentrations of specific elements, in single-phase concentrated solid solution alloys can lead to substantial reduction in electron mean free path and orders of magnitude decrease in electrical and thermal conductivity. The subsequently slow energy dissipation affects defect dynamics at the early stages, and consequentially may result in less deleterious defects. Suppressed damage accumulation with increasing chemical disorder from pure nickel to binary and to more complex quaternary solid solutions is observed. Understanding and controlling energy dissipation and defect dynamics by altering alloy complexity may pave the way for new design principles of radiation-tolerant structural alloys for energy applications. PMID:26507943

Estimation of the residual bromine concentration after disinfection of cooling water by statistical evaluation.

PubMed

Megalopoulos, Fivos A; Ochsenkuehn-Petropoulou, Maria T

2015-01-01

A statistical model based on multiple linear regression is developed, to estimate the bromine residual that can be expected after the bromination of cooling water. Make-up water sampled from a power plant in the Greek territory was used for the creation of the various cooling water matrices under investigation. The amount of bromine fed to the circuit, as well as other important operational parameters such as concentration at the cooling tower, temperature, organic load and contact time are taken as the independent variables. It is found that the highest contribution to the model's predictive ability comes from cooling water's organic load concentration, followed by the amount of bromine fed to the circuit, the water's mean temperature, the duration of the bromination period and finally its conductivity. Comparison of the model results with the experimental data confirms its ability to predict residual bromine given specific bromination conditions.

Evaluating the toxicity of food processing wastes as co-digestion substrates with dairy manure.

PubMed

Lisboa, Maria Sol; Lansing, Stephanie

2014-07-01

Studies have shown that including food waste as a co-digestion substrate in the anaerobic digestion of livestock manure can increase energy production. However, the type and inclusion rate of food waste used for co-digestion need to be carefully considered in order to prevent adverse conditions in the digestion environment. This study determined the effect of increasing the concentration (2%, 5%, 15% and 30%, by volume) of four food-processing wastes (meatball, chicken, cranberry and ice cream processing wastes) on methane production. Anaerobic toxicity assay (ATA) and specific methanogenic activity (SMA) tests were conducted to determine the concentration at which each food waste became toxic to the digestion environment. Decreases in methane production were observed at concentrations above 5% for all four food waste substrates, with up to 99% decreases in methane production at 30% food processing wastes (by volume). Copyright © 2014 Elsevier Ltd. All rights reserved.

Overview of the Benzene and Other Toxics Exposure (BEE-TEX) Field Study.

PubMed

Olaguer, Eduardo P

2015-01-01

The Benzene and other Toxics Exposure (BEE-TEX) field study was an experimental campaign designed to demonstrate novel methods for measuring ambient concentrations of hazardous air pollutants (HAPs) in real time and to attribute these concentrations to quantified releases from specific emission points in industrial facilities while operating outside facility fence lines. BEE-TEX was conducted in February 2015 at three neighboring communities in the Houston Ship Channel of Texas, where a large number of petrochemical facilities are concentrated. The novel technologies deployed during BEE-TEX included: (1) tomographic remote sensing based on differential optical absorption spectroscopy; (2) real-time broadcasting of ambient air monitoring data over the World Wide Web; (3) real-time source attribution and quantification of HAP emissions based on either tomographic or mobile measurement platforms; and (4) the use of cultured human lung cells in vitro as portable indicators of HAP exposure.

Overview of the Benzene and Other Toxics Exposure (BEE-TEX) Field Study

PubMed Central

Olaguer, Eduardo P.

2015-01-01

The Benzene and other Toxics Exposure (BEE-TEX) field study was an experimental campaign designed to demonstrate novel methods for measuring ambient concentrations of hazardous air pollutants (HAPs) in real time and to attribute these concentrations to quantified releases from specific emission points in industrial facilities while operating outside facility fence lines. BEE-TEX was conducted in February 2015 at three neighboring communities in the Houston Ship Channel of Texas, where a large number of petrochemical facilities are concentrated. The novel technologies deployed during BEE-TEX included: (1) tomographic remote sensing based on differential optical absorption spectroscopy; (2) real-time broadcasting of ambient air monitoring data over the World Wide Web; (3) real-time source attribution and quantification of HAP emissions based on either tomographic or mobile measurement platforms; and (4) the use of cultured human lung cells in vitro as portable indicators of HAP exposure. PMID:26549972

Quality of water in Luxapallia Creek at Columbus, Mississippi

USGS Publications Warehouse

Kalkhoff, Stephen J.

1982-01-01

The results of a water quality study of a short reach of Luxapallila Creek at Columbus, Mississippi, during September 9-12, 1979, indicate that the water is colored (60 units) and has a low dissolved solids content (44 mg/L). The dissolved oxygen concentration, temperature, and pH of the water in Luxapallila Creek changed a slightly downstream through the study reach. The mean specific conductance almost doubled and the five-day biochemical oxygen demand load increased over four times through the study reach. The fecal coliform to fecal streptococcus ration of 3 to 5 samples collected at the downstream site was greater than 4.0, strongly suggesting the presence of human waste. The concentrations of iron and manganese at the downstream site exceeded the U.S. Environmental Protection Agency 's criteria for domestic water supplies. High concentrations of iron, manganese, and lead also were present in a bottom material sample at the downstream site. (USGS)

Excess labile carbon promotes the expression of virulence factors in coral reef bacterioplankton.

PubMed

Cárdenas, Anny; Neave, Matthew J; Haroon, Mohamed Fauzi; Pogoreutz, Claudia; Rädecker, Nils; Wild, Christian; Gärdes, Astrid; Voolstra, Christian R

2018-01-01

Coastal pollution and algal cover are increasing on many coral reefs, resulting in higher dissolved organic carbon (DOC) concentrations. High DOC concentrations strongly affect microbial activity in reef waters and select for copiotrophic, often potentially virulent microbial populations. High DOC concentrations on coral reefs are also hypothesized to be a determinant for switching microbial lifestyles from commensal to pathogenic, thereby contributing to coral reef degradation, but evidence is missing. In this study, we conducted ex situ incubations to assess gene expression of planktonic microbial populations under elevated concentrations of naturally abundant monosaccharides (glucose, galactose, mannose, and xylose) in algal exudates and sewage inflows. We assembled 27 near-complete (>70%) microbial genomes through metagenomic sequencing and determined associated expression patterns through metatranscriptomic sequencing. Differential gene expression analysis revealed a shift in the central carbohydrate metabolism and the induction of metalloproteases, siderophores, and toxins in Alteromonas, Erythrobacter, Oceanicola, and Alcanivorax populations. Sugar-specific induction of virulence factors suggests a mechanistic link for the switch from a commensal to a pathogenic lifestyle, particularly relevant during increased algal cover and human-derived pollution on coral reefs. Although an explicit test remains to be performed, our data support the hypothesis that increased availability of specific sugars changes net microbial community activity in ways that increase the emergence and abundance of opportunistic pathogens, potentially contributing to coral reef degradation.

Hydrogeology, water quality, and ecology of Anderton Branch near the Quail Hollow Landfill, Bedford County, Tennessee, 1995-99

USGS Publications Warehouse

Farmer, James

2004-01-01

The Quail Hollow Landfill, located in southeastern Bedford County on the Highland Rim overlooking the Central Basin karst region of Tennessee, is constructed on the gravelly, clay-rich residuum of the Fort Payne Formation of Mississippian age. A conceptual hydrologic model of the landfill indicated that Anderton Branch was at risk of being affected by the landfill. Ground water flowing beneath the landfill mixes with percolating rainwater that has passed through the landfill and discharges to the surface from numerous weeps, seeps, and springs present in the area. Anderton Branch, adjacent to the landfill site on the north and east, receives most of the discharge from these weeps, seeps, and springs. Anderton Branch also receives water from the Powell Branch drainage basin to the west and south because of diverted flow of ground water through Harrison Spring Cave. The U.S. Geological Survey, in cooperation with the Bedford County Solid Waste Authority, conducted a study to evaluate the effect of the Quail Hollow Landfill on ground- and surface-water quality. During storm runoff, specific conductance was elevated, and cadmium, iron, manganese, lead, and nickel concentrations in Anderton Branch frequently exceeded maximum contaminant levels for drinking water for the State of Tennessee. High chloride inputs to Anderton Branch were detected at two locations?a barnyard straddling the stream and a tributary draining a pond that receives water directly from the landfill. The chloride inputs probably contribute to chloride load levels that are three times higher for Anderton Branch than for the control stream Anthony Branch. Although toxic volatile organic compounds were detected in water from monitoring wells at the landfill, no organic contaminants were detected in domestic water wells adjacent to the landfill or in Anderton Branch. Sons Spring, a karst spring near the landfill, has been affected by the landfill as indicated by an increase in chloride concentrations from 4 milligrams per liter in 1974 to 59 milligrams per liter in 1996. Analysis of water samples from Sons Spring detected concentrations of nickel that exceeded primary drinking-water standards and Tennessee Department of Environment and Conservation fish and aquatic life chronic standards. Trichloroethene, 1,1-dichloroethene, and 1,1-dichloroethane also were detected at Sons Spring. The presence of these chlorinated solvents imply the landfill origin of the contaminants in Sons Spring. Continuous monitoring at Sons Spring indicated a pattern of decreased specific conductance and lower contaminant concentrations after a storm. Contaminant concentrations increased with specific conductance to pre-storm levels after several days. The benthic macroinvertebrate community in Anderton Branch adjacent to the landfill was not different from the communities at control sites upstream and in Anthony Branch. Sons Spring, however, has low abundance and numbers of benthic macroinvertebrate taxa. Toxicity studies using Ceriodaphnia dubia indicated no toxicity in the base flow or storm water in Anderton Branch or in a tributary draining a pond that receives water from the landfill and Sons Spring; however, water collected from Sons Spring resulted in 100 percent mortality to all organisms within 48 hours. High concentrations of nickel were detected in crayfish tissue from control sites and Anderton Branch. Analysis of sediment samples also indicates nickel concentrations are high at control sites upstream of the landfill. Increased levels of the biomarker metallothionein detected in crayfish from Anderton Branch likely are not caused by nickel or cadmium because the levels present in the tissue are not correlated with metallothionein levels. Despite the high levels of certain metals in Anderton Branch during storm flow, the lack of toxicity and the health of the benthic community imply no detectable negative effect from the landfill to the stream. Sons Spring, howe

Quality-Assurance Data for Routine Water Analyses by the U.S. Geological Survey Laboratory in Troy, New York--July 1999 through June 2001

USGS Publications Warehouse

Lincoln, Tricia A.; Horan-Ross, Debra A.; McHale, Michael R.; Lawrence, Gregory B.

2006-01-01

The laboratory for analysis of low-ionic-strength water at the U.S. Geological Survey (USGS) Water Science Center in Troy, N.Y., analyzes samples collected by USGS projects throughout the Northeast. The laboratory's quality-assurance program is based on internal and interlaboratory quality-assurance samples and quality-control procedures that were developed to ensure proper sample collection, processing, and analysis. The quality-assurance and quality-control data were stored in the laboratory's LabMaster data-management system, which provides efficient review, compilation, and plotting of data. This report presents and discusses results of quality-assurance and quality-control samples analyzed from July 1999 through June 2001. Results for the quality-control samples for 18 analytical procedures were evaluated for bias and precision. Control charts indicate that data for eight of the analytical procedures were occasionally biased for either high-concentration or low-concentration samples but were within control limits; these procedures were: acid-neutralizing capacity, total monomeric aluminum, total aluminum, calcium, chloride and nitrate (ion chromatography and colormetric method) and sulfate. The total aluminum and dissolved organic carbon procedures were biased throughout the analysis period for the high-concentration sample, but were within control limits. The calcium and specific conductance procedures were biased throughout the analysis period for the low-concentration sample, but were within control limits. The magnesium procedure was biased for the high-concentration and low concentration samples, but was within control limits. Results from the filter-blank and analytical-blank analyses indicate that the procedures for 14 of 15 analytes were within control limits, although the concentrations for blanks were occasionally outside the control limits. The data-quality objective was not met for dissolved organic carbon. Sampling and analysis precision are evaluated herein in terms of the coefficient of variation obtained for triplicate samples in the procedures for 17 of the 18 analytes. At least 90 percent of the samples met data-quality objectives for all analytes except ammonium (81 percent of samples met objectives), chloride (75 percent of samples met objectives), and sodium (86 percent of samples met objectives). Results of the USGS interlaboratory Standard Reference Sample (SRS) Project indicated good data quality over the time period, with most ratings for each sample in the good to excellent range. The P-sample (low-ionic-strength constituents) analysis had one satisfactory rating for the specific conductance procedure in one study. The T-sample (trace constituents) analysis had one satisfactory rating for the aluminum procedure in one study and one unsatisfactory rating for the sodium procedure in another. The remainder of the samples had good or excellent ratings for each study. Results of Environment Canada's National Water Research Institute (NWRI) program indicated that at least 89 percent of the samples met data-quality objectives for 10 of the 14 analytes; the exceptions were ammonium, total aluminum, dissolved organic carbon, and sodium. Results indicate a positive bias for the ammonium procedure in all studies. Data-quality objectives were not met in 50 percent of samples analyzed for total aluminum, 38 percent of samples analyzed for dissolved organic carbon, and 27 percent of samples analyzed for sodium. Results from blind reference-sample analyses indicated that data-quality objectives were met by at least 91 percent of the samples analyzed for calcium, chloride, fluoride, magnesium, pH, potassium, and sulfate. Data-quality objectives were met by 75 percent of the samples analyzed for sodium and 58 percent of the samples analyzed for specific conductance.

Association of IL-6 with PM2.5 Components: Importance of Characterizing Filter-Based PM2.5 Following Extraction.

PubMed

Roper, Courtney; Chubb, Lauren G; Cambal, Leah; Tunno, Brett; Clougherty, Jane E; Fattman, Cheryl; Mischler, Steven E

2017-01-01

Filter-based toxicology studies are conducted to establish the biological plausibility of the well-established health impacts associated with fine particulate matter (PM 2.5 ) exposure. Ambient PM 2.5 collected on filters is extracted into solution for toxicology applications, but frequently, characterization is nonexistent or only performed on filter-based PM 2.5 , without consideration of compositional differences that occur during the extraction processes. To date, the impact of making associations to measured components in ambient instead of extracted PM 2.5 has not been investigated. Filter-based PM 2.5 was collected at locations ( n = 5) and detailed characterization of both ambient and extracted PM 2.5 was performed. Alveolar macrophages (AMJ2-C11) were exposed (3, 24, and 48 h) to PM 2.5 and the pro-inflammatory cytokine interleukin (IL)-6 was measured. IL-6 release differed significantly between PM 2.5 collected from different locations; surprisingly, IL-6 release was highest following treatment with PM 2.5 from the lowest ambient concentration location. IL-6 was negatively correlated with the sum of ambient metals analyzed, as well as with concentrations of specific constituents which have been previously associated with respiratory health effects. However, positive correlations of IL-6 with extracted concentrations indicated that the negative associations between IL-6 and ambient concentrations do not accurately represent the relationship between inflammation and PM 2.5 exposure. Additionally, seven organic compounds had significant associations with IL-6 release when considering ambient concentrations, but they were not detected in the extracted solution. Basing inflammatory associations on ambient concentrations that are not necessarily representative of in vitro exposures creates misleading results; this study highlights the importance of characterizing extraction solutions to conduct accurate health impact research.

Hydrogeology and water quality of five principal aquifers in the Lower Platte South Natural Resources District, eastern Nebraska, 1994

USGS Publications Warehouse

Druliner, A.D.; Mason, J.P.

2001-01-01

The U.S. Geological Survey, in cooperation with the Lower Platte South Natural Resources District, conducted a hydrogeologic and water-quality reconnaissance study of the five principal aquifers in deposits of Quaternary age in the Natural Resources District. The purpose of the study was to delineate the approximate extent of the aquifers, to estimate volumes of drainable water in three aquifers, to provide information that could be useful in designing future ground-water-quality monitoring, and to determine baseline water-quality conditions in the aquifers, focusing on nitrate concentrations. The approximate lateral boundaries of the Dwight-Valparaiso, Crete-Princeton-Adams, and Waverly aquifers were defined as areas in which the thickness of continuous sand and gravel deposits was less than 40 feet. The three aquifers were determined to contain about 1,340,000; 1,540,000; and 172,000 acre-feet of drainable water, respectively, assuming a specific yield of 0.20. During the summer of 1994, ground-water samples were collected from 46 wells in the five aquifers and analyzed for nitrate and screened for triazine herbicides. Additionally, water samples from 39 of these wells were analyzed for major ions, iron, and manganese, and 35 were analyzed for radon. Water-quality analyses revealed that the water in the five aquifers had specific conductances that ranged from 399 to 2,040 micro-siemens per centimeter and was a calcium-carbonate to calcium-magnesium-sodium carbonate type. The most mineralized water samples were from the Crete-Princeton-Adams aquifer, which contained a median concentration of dissolved solids of 520 milligrams per liter. Concentrations of nitrate in water samples from the aquifers ranged from less than 0.05 to 23 milligrams per liter as nitrogen, and only six water samples exceeded the Maximum Contaminant Level established by the U.S. Environmental Protection Agency of 10 milligrams per liter. The median concentration of radon for water samples from the five aquifers was 300 picocuries per liter, which is the proposed Maximum Contaminant Level. Water samples from the Crete-Princeton-Adams and Waverly aquifers had the largest concentrations of radon among the five aquifers. The Crete-Princeton-Adams aquifer had a median concentration of 440 picocuries per liter, and the Waverly aquifer had a median concentration of 390 picocuries per liter. Herbicides were detected in water from only six wells, which were in four of the five aquifers. Atrazine, metabolites of atrazine, metolachlor, and metribuzin were detected in concentrations generally less than 1.00 microgram per liter.

Programmable graphene doping via electron beam irradiation.

PubMed

Zhou, Yangbo; Jadwiszczak, Jakub; Keane, Darragh; Chen, Ying; Yu, Dapeng; Zhang, Hongzhou

2017-06-29

Graphene is a promising candidate to succeed silicon based devices, and the conventional strategies for fabrication and testing of graphene-based electronics often utilise an electron beam. Here, we report on a systematic study of the effect of electron beam exposure on graphene devices. We realise reversible doping of on-chip graphene using a focused electron beam. Our results demonstrate site-specific control of carrier type and concentration achievable by modulating the charge distribution in the substrate. The effect of substrate-embedded charges on carrier mobility and conductivity of graphene is studied, with a dielectric screening model proposed to explain the effective n-type and p-type doping produced at different beam energies. Multiple logic operations are thus implemented in a single graphene sheet by using site-specific e-beam irradiation. We extend the phenomenon to MoS 2 , generalising it to conductive two-dimensional materials. Our results are of importance to imaging, in situ characterisation and lithographic techniques employed to investigate 2D materials.

Comparing biomarker measurements to a normal range: when ...

EPA Pesticide Factsheets

This commentary is the second of a series outlining one specific concept in interpreting biomarkers data. In the first, an observational method was presented for assessing the distribution of measurements before making parametric calculations. Here, the discussion revolves around the next step, the choice of using standard error of the mean or the calculated standard deviation to compare or predict measurement results. The National Exposure Research Laboratory’s (NERL’s) Human Exposure and Atmospheric Sciences Division (HEASD) conducts research in support of EPA’s mission to protect human health and the environment. HEASD’s research program supports Goal 1 (Clean Air) and Goal 4 (Healthy People) of EPA’s strategic plan. More specifically, our division conducts research to characterize the movement of pollutants from the source to contact with humans. Our multidisciplinary research program produces Methods, Measurements, and Models to identify relationships between and characterize processes that link source emissions, environmental concentrations, human exposures, and target-tissue dose. The impact of these tools is improved regulatory programs and policies for EPA.

Concentration dependence of molal conductivity and dielectric constant of 1-alcohol electrolytes using the compensated arrhenius formalism.

PubMed

Fleshman, Allison M; Petrowsky, Matt; Frech, Roger

2013-05-02

The molal conductivity of liquid electrolytes with low static dielectric constants (ε(s) < 10) decreases to a minimum at low concentrations (region I) and increases to a maximum at higher concentrations (region II) when plotted against the square root of the concentration. This behavior is investigated by applying the compensated Arrhenius formalism (CAF) to the molal conductivity, Λ, of a family of 1-alcohol electrolytes over a broad concentration range. A scaling procedure is applied that results in an energy of activation (E(a)) and an exponential prefactor (Λ0) that are both concentration dependent. It is shown that the increasing molal conductivity in region II results from the combined effect of (1) a decrease in the energy of activation calculated from the CAF, and (2) an inherent concentration dependence in the exponential prefactor that is partly due to the dielectric constant.

Season, molt, and body size influence mercury concentrations in grebes.

PubMed

Hartman, C Alex; Ackerman, Joshua T; Herzog, Mark P; Eagles-Smith, Collin A

2017-10-01

We studied seasonal and physiological influences on mercury concentrations in western grebes (Aechmophorus occidentalis) and Clark's grebes (A. occidentalis) across 29 lakes and reservoirs in California, USA. Additionally, at three of these lakes, we conducted a time series study, in which we repeatedly sampled grebe blood mercury concentrations during the spring, summer, and early fall. Grebe blood mercury concentrations were higher among males (0.61 ± 0.12 μg/g ww) than females (0.52 ± 0.10 μg/g ww), higher among Clark's grebes (0.58 ± 0.12 μg/g ww) than western grebes (0.51 ± 0.10 μg/g ww), and exhibited a strong seasonal pattern (decreasing by 60% from spring to fall). Grebe blood THg concentrations exhibited a shallow, inverse U-shaped pattern with body size, and was lowest among the smallest and largest grebes. Further, the relationship between grebe blood mercury concentrations and wing primary feather molt exhibited a shallow U-shaped pattern, where mercury concentrations were highest among birds that had not yet begun molting, decreased approximately 24% between pre-molt and late molt, and increased approximately 19% from late molt to post-molt. Because grebes did not begin molting until mid-summer, lower grebe blood mercury concentrations observed in late summer and early fall were consistent with the onset of primary feather molt. However, because sampling date was a much stronger predictor of grebe mercury concentrations than molt, other seasonally changing environmental factors likely played a larger role than molt in the seasonal variation in grebe mercury concentrations. In the time series study, we found that seasonal trends in grebe mercury concentrations were not consistent among lakes, indicating that lake-specific variation in mercury dynamics influence the overall seasonal decline in grebe blood mercury concentrations. These results highlight the importance of accounting for sampling date, as well as ecological processes that may influence mercury concentrations, when developing monitoring programs to assess site-specific exposure risk of mercury to wildlife. Published by Elsevier Ltd.

Water-quality characteristics of six small, semiarid watersheds in the Green River coal region of Colorado

USGS Publications Warehouse

Turk, John T.; Parker, Randolph S.

1982-01-01

Analysis of major and trace constituents in streams flowing through six semiarid watersheds indicates that the stream chemistry is characterized by saturation with respect to common carbonate minerals (calcium, magnesium, iron, manganese, and lead). The solubility of the carbonate minerals may be a major control on the absolute and relative concentrations of calcium, magnesium, bicarbonate, iron, manganese, and lead; however, other mechanisms probably control the concentrations of cadmium and zinc. Statistical analyses indicate that the mean concentrations of the major ions in the two climatic areas studied are significantly (P=0.05) different from one another, with larger mean concentrations in the more arid area. Trace-metal concentrations were similar from one area to another and indistinguishable from site to site (P=0.05) for lead, cadmium, and zinc. Linear regressions of major ion concentration to specific conductance are similar in both areas for sodium, bicarbonate, sulfate, and chloride. Results of the study may be useful in providing a first approximation of stream chemistry in other watersheds with the same geologic setting, determining watersheds with similar geochemical controls, and determining future changes in stream chemistry in the watersheds studied. (USGS)

What goes on behind closed doors: physiological vs. pharmacological steroid hormone actions

PubMed Central

Simons, S. Stoney

2009-01-01

Summary Steroid hormone-activated receptor proteins are among the best understood class of factors for altering gene transcription in cells. Steroid receptors are of major importance in maintaining normal human physiology by responding to circulating concentrations of steroid in the nM range. Nonetheless, most studies of steroid receptor action have been conducted using the supra-physiological conditions of saturating concentrations (≥100 nM) of potent synthetic steroid agonists. Here we summarize the recent developments arising from experiments using two clinically relevant conditions: subsaturating concentrations of agonist (to mimic the circulating concentrations in mammals) and saturating concentrations of antagonists (which are employed in endocrine therapies to block the actions of endogenous steroids). These studies have revealed new facets of steroid hormone action that could not be uncovered by conventional experiments with saturating concentrations of agonist steroids, such as a plethora of factors/conditions for the differential control of gene expression by physiological levels of steroid, a rational approach for examining the gene-specific variations in partial agonist activity of antisteroids, and a dissociation of steroid potency and efficacy that implies the existence of separate, and possibly novel, mechanistic steps and cofactors. PMID:18623071

Critical predicted no effect concentrations (PNECs) should not be based on a single toxicity test.

PubMed

Chapman, Peter M; Elphick, James R

2015-05-01

Predicted no-effect concentrations (PNECs), which represent the concentration of a substance below which an unacceptable effect most likely will not occur, are widely used for risk assessment and in environmental policy and regulation. They are typically based on single-species laboratory toxicity tests; often, a single test result for the most sensitive endpoints drives the derivation of a PNEC. In the present study, the authors provide a case study emphasizing the importance of determining the reliability of those most sensitive endpoints. Five 21-d Daphnia magna toxicity tests conducted using the same procedures by 2 laboratories gave 20% inhibitory concentration responses to a specific ionic composition of total dissolved solids that varied from 684 mg/L to more than 1510 mg/L. The concentration-response curve was shallow; thus, these differences could have been attributable to chance alone. The authors strongly recommend that the most sensitive endpoints that determine PNECs not be based on a single toxicity test result but rather on the geometric mean of at least 3 test results to adequately assess and bound test variability, especially when the concentration-response curve is shallow. © 2015 SETAC.

Sanitary quality of the Jordan River in Salt Lake County, Utah

USGS Publications Warehouse

Thompson, K.R.

1984-01-01

This investigation of the sanitary quality of the Jordan River was conducted from July 1980 to October 1982 using indicator bacteria rather than specific pathogens. A serious sanitary problem was identified. Concentrations of total coliform bacteria often exceeded 5,000 colonies per 100 milliliters and concentrations of fecal coliform bacteria often exceeded 2,000 colonies per 100 milliliters in the lower reaches of the river. At times these levels were greatly exceeded. The most conspicuous aspect of the bacteriological data is its extreme variability. Seven waste-water treatment plants, seven major tributaries, numerous storm conduits, irrigation-return flow, and other sources all contribute to the dynamic system that determines the sanitary quality of the river. Because of this variability the sanitary quality of the river cannot be predicted at any one time. In general, concentrations of all three indicator bacteria increased in a downstream direction. Storm runoff from urban areas contributed large concentrations of indicator bacteria to the river. Regression analysis of 9 years of data collected at 1700 South Street showed a significant positive correlation between both fecal coliform and fecal streptococcal concentrations versus time. Concentrations of fecal coliform and fecal streptococci have both been increasing since 1974 at 1700 South Street. (USGS)

Nuclear track-based biosensors with the enzyme laccase

NASA Astrophysics Data System (ADS)

García-Arellano, H.; Fink, D.; Muñoz Hernández, G.; Vacík, J.; Hnatowicz, V.; Alfonta, L.

2014-08-01

A new type of biosensors for detecting phenolic compounds is presented here. These sensors consist of thin polymer foils with laccase-clad etched nuclear tracks. The presence of suitable phenolic compounds in the sensors leads to the formation of enzymatic reaction products in the tracks, which differ in their electrical conductivities from their precursor materials. These differences correlate with the concentrations of the phenolic compounds. Corresponding calibration curves have been established for a number of compounds. The sensors thus produced are capable to cover between 5 and 9 orders of magnitude in concentration - in the best case down to some picomoles. The sensor's detection sensitivity strongly depends on the specific compound. It is highest for caffeic acid and acid blue 74, followed by ABTS and ferulic acid.

Synthesis and thermo-physical properties of deep eutectic solvent-based graphene nanofluids

NASA Astrophysics Data System (ADS)

Fang, Y. K.; Osama, M.; Rashmi, W.; Shahbaz, K.; Khalid, M.; Mjalli, F. S.; Farid, M. M.

2016-02-01

This study introduces a new class of heat transfer fluids by dispersing functionalised graphene oxide nanoparticles (GNPs) in ammonium and phosphonium-based deep eutectic solvents (DESs) without the aid of a surfactant. Different molar ratios of salts and hydrogen bond donors (HBD) were used to synthesise DESs for the preparation of different concentrations of graphene nanofluids (GNFs). The concentrations of GNPs were 0.01 wt%, 0.02 wt% and 0.05 wt %. Homogeneous and stable suspensions of nanofluids were obtained by high speed homogenisation and an ultrasonication process. The stability of the GNFs was determined through visual observation for 4 weeks followed by a centrifugal process (5000-20 000 rpm) for 30 min in addition to zeta potential studies. Dispersion of the GNPs in DES was observed using an optical microscope. The synthesised DES-based GNFs showed no particle agglomeration and formation of sediments in the nanofluids. Thermo-physical properties such as thermal conductivity and specific heat of the nanofluids were also investigated in this research. The highest thermal conductivity enhancement of 177% was observed. The findings of this research provide a new class of engineered fluid for heat transfer applications as a function of temperature, type and composition DESs as well as the GNPs concentration.

Biological effects of short-term, high-concentration exposure to methyl isocyanate. V. Morphologic evaluation of rat and guinea pig lungs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fowler, E.H.; Dodd, D.E.; Troup, C.M.

1987-06-01

The morphologic changes induced in the lungs of rats and guinea pigs exposed to high concentrations of MIC vapor (100, 600, and 1000 ppm in the rat and 25, 125, 225, and 675 ppm in the guinea pig) for a short time (15 min) in a static exposure chamber were evaluated at varying postexposure periods (0, 1, 2, and 4, and 16 hr). The 675 ppm-exposed guinea pigs were evaluated only immediately following removal from the chamber. Attention was primarily focused on the intrapulmonary conducting airways and the parenchyma (gas exchange region) of the lungs. The severity of morphologic changesmore » observed by light microscopy was directly correlated with exposure concentration and time postexposure in both species. Specifically, degenerative changes were observed in the bronchial, bronchiolar, and alveolar epithelium in both species. Quantitative differences were observed; 100 ppm of MIC in the rat resulted in much less damage than did 125 ppm of MIC in the guinea pig. Morphologic evidence of sloughing of large sheets of conducting airway epithelium with fibrin buildup and increased mucus production resulted in plugging of major airways and atelectasis. These observations support the hypothesis that tissue hypoxia was a major contributing factor resulting in death.« less

Synthesis and thermo-physical properties of deep eutectic solvent-based graphene nanofluids.

PubMed

Fang, Y K; Osama, M; Rashmi, W; Shahbaz, K; Khalid, M; Mjalli, F S; Farid, M M

2016-02-19

This study introduces a new class of heat transfer fluids by dispersing functionalised graphene oxide nanoparticles (GNPs) in ammonium and phosphonium-based deep eutectic solvents (DESs) without the aid of a surfactant. Different molar ratios of salts and hydrogen bond donors (HBD) were used to synthesise DESs for the preparation of different concentrations of graphene nanofluids (GNFs). The concentrations of GNPs were 0.01 wt%, 0.02 wt% and 0.05 wt %. Homogeneous and stable suspensions of nanofluids were obtained by high speed homogenisation and an ultrasonication process. The stability of the GNFs was determined through visual observation for 4 weeks followed by a centrifugal process (5000-20,000 rpm) for 30 min in addition to zeta potential studies. Dispersion of the GNPs in DES was observed using an optical microscope. The synthesised DES-based GNFs showed no particle agglomeration and formation of sediments in the nanofluids. Thermo-physical properties such as thermal conductivity and specific heat of the nanofluids were also investigated in this research. The highest thermal conductivity enhancement of 177% was observed. The findings of this research provide a new class of engineered fluid for heat transfer applications as a function of temperature, type and composition DESs as well as the GNPs concentration.

Results of external quality-assurance program for the National Atmospheric Deposition Program and National Trends Network during 1985

USGS Publications Warehouse

Brooks, M.H.; Schroder, L.J.; Willoughby, T.C.

1988-01-01

External quality assurance monitoring of the National Atmospheric Deposition Program (NADP) and National Trends Network (NTN) was performed by the U.S. Geological Survey during 1985. The monitoring consisted of three primary programs: (1) an intersite comparison program designed to assess the precision and accuracy of onsite pH and specific conductance measurements made by NADP and NTN site operators; (2) a blind audit sample program designed to assess the effect of routine field handling on the precision and bias of NADP and NTN wet deposition data; and (3) an interlaboratory comparison program designed to compare analytical data from the laboratory processing NADP and NTN samples with data produced by other laboratories routinely analyzing wet deposition samples and to provide estimates of individual laboratory precision. An average of 94% of the site operators participated in the four voluntary intersite comparisons during 1985. A larger percentage of participating site operators met the accuracy goal for specific conductance measurements (average, 87%) than for pH measurements (average, 67%). Overall precision was dependent on the actual specific conductance of the test solution and independent of the pH of the test solution. Data for the blind audit sample program indicated slight positive biases resulting from routine field handling for all analytes except specific conductance. These biases were not large enough to be significant for most data users. Data for the blind audit sample program also indicated that decreases in hydrogen ion concentration were accompanied by decreases in specific conductance. Precision estimates derived from the blind audit sample program indicate that the major source of uncertainty in wet deposition data is the routine field handling that each wet deposition sample receives. Results of the interlaboratory comparison program were similar to results of previous years ' evaluations, indicating that the participating laboratories produced comparable data when they analyzed identical wet deposition samples, and that the laboratory processing NADP and NTN samples achieved the best analyte precision of the participating laboratories. (Author 's abstract)

Quality of water and bottom material in Breckenridge Reservoir, Virginia, September 2008 through August 2009

USGS Publications Warehouse

Lotspeich, Russell

2012-01-01

Breckenridge Reservoir is located within the U.S. Marine Corps Base in Quantico, which is in the Potomac River basin and the Piedmont Physiographic Province of northern Virginia. Because it serves as the principal water supply for the U.S. Marine Corps Base in Quantico, an assessment of the water-quality of Breckenridge Reservoir was initiated. Water samples were collected and physical properties were measured by the U.S. Geological Survey at three sites in Breckenridge Reservoir, and physical properties were measured at six additional reservoir sites from September 2008 through August 2009. Water samples were also collected and physical properties were measured in each of the three major tributaries to Breckenridge Reservoir: North Branch Chopawamsic Creek, Middle Branch Chopawamsic Creek, and South Branch Chopawamsic Creek. One site on each tributary was sampled at least five times during the study. Monthly profiles were conducted for water temperature, dissolved-oxygen concentrations, specific conductance, pH, and turbidity measured at 2-foot intervals throughout the water column of the reservoir. These profiles were conducted at nine sites in the reservoir, and data values were measured at these sites from the water surface to the bottom of the reservoir. These profiles were conducted along three cross sections and were used to define the characteristics of the entire water column of the reservoir. The analytical results of reservoir and tributary samples collected and physical properties measured during this study were compared to ambient water-quality standards of the Virginia Department of Environmental Quality and Virginia State Water Control Board. Water temperature, dissolved-oxygen concentration, specific conductance, pH, and turbidity measured in Breckenridge Reservoir generally indicated a lack of stratification in the water column of the reservoir throughout the study period. This is unlike most other reservoirs in the region and may be influenced by the reservoir's relatively short length and the aerators that operate in the reservoir near the spillway. In general, the water-quality of Breckenridge Reservoir is similar to other reservoirs in the region, and the measurements made during this study indicate that the reservoir is healthy and is not in violation of published State Water Control Board ambient water-quality standards. Water samples at three reservoir sites were analyzed for 53 pesticides, but only atrazine was found to be above the laboratory minimum reporting level. Atrazine concentrations of 0.008 and 0.010 microgram per liter near the surface and bottom of the reservoir, respectively, were found at all three sampling locations. Bottom-material samples were collected for analysis of trace elements at all three reservoir sampling sites. Concentrations of arsenic, cadmium, and mercury in bottom material were similar to those analyzed in other reservoirs in the region. However, most other constituents that were collected from Breckenridge Reservoir, especially iron and lead, showed much higher concentrations than the other reservoirs. During the course of the study, increased turbidity and Escherichia coli bacteria counts were observed during or after periods of increased tributary discharge, and Secchi-disk depths decreased during those same periods. These streamflow and water-quality indicators suggest a close relationship between Breckenridge Reservoir and its tributaries.

Reconstructing Historical VOC Concentrations in Drinking Water for Epidemiological Studies at a U.S. Military Base: Summary of Results

PubMed Central

Maslia, Morris L.; Aral, Mustafa M.; Ruckart, Perri Z.; Bove, Frank J.

2017-01-01

A U.S. government health agency conducted epidemiological studies to evaluate whether exposures to drinking water contaminated with volatile organic compounds (VOC) at U.S. Marine Corps Base Camp Lejeune, North Carolina, were associated with increased health risks to children and adults. These health studies required knowledge of contaminant concentrations in drinking water—at monthly intervals—delivered to family housing, barracks, and other facilities within the study area. Because concentration data were limited or unavailable during much of the period of contamination (1950s–1985), the historical reconstruction process was used to quantify estimates of monthly mean contaminant-specific concentrations. This paper integrates many efforts, reports, and papers into a synthesis of the overall approach to, and results from, a drinking-water historical reconstruction study. Results show that at the Tarawa Terrace water treatment plant (WTP) reconstructed (simulated) tetrachloroethylene (PCE) concentrations reached a maximum monthly average value of 183 micrograms per liter (μg/L) compared to a one-time maximum measured value of 215 μg/L and exceeded the U.S. Environmental Protection Agency’s current maximum contaminant level (MCL) of 5 μg/L during the period November 1957–February 1987. At the Hadnot Point WTP, reconstructed trichloroethylene (TCE) concentrations reached a maximum monthly average value of 783 μg/L compared to a one-time maximum measured value of 1400 μg/L during the period August 1953–December 1984. The Hadnot Point WTP also provided contaminated drinking water to the Holcomb Boulevard housing area continuously prior to June 1972, when the Holcomb Boulevard WTP came on line (maximum reconstructed TCE concentration of 32 μg/L) and intermittently during the period June 1972–February 1985 (maximum reconstructed TCE concentration of 66 μg/L). Applying the historical reconstruction process to quantify contaminant-specific monthly drinking-water concentrations is advantageous for epidemiological studies when compared to using the classical exposed versus unexposed approach. PMID:28868161

Characterization of the quality of water, bed sediment, and fish in Mittry Lake, Arizona, 2014–15

USGS Publications Warehouse

Hermosillo, Edyth; Coes, Alissa L.

2017-03-01

Water, bed-sediment, and fish sampling was conducted in Mittry Lake, Arizona, in 2014–15 to establish current water-quality conditions of the lake. The parameters of temperature, dissolved-oxygen concentration, specific conductance, and alkalinity were measured in the field. Water samples were collected and analyzed for dissolved major ions, dissolved trace elements, dissolved nutrients, dissolved organic carbon, dissolved pesticides, bacteria, and suspended-sediment concentrations. Bed-sediment and fish samples were analyzed for trace elements, halogenated compounds, total mercury, and methylmercury.U.S. Environmental Protection Agency secondary maximum contaminant levels in drinking water were exceeded for sulfate, chloride, and manganese in the water samples. Trace-element concentrations were relatively similar between the inlet, middle, and outlet locations. Concentrations for nutrients in all water samples were below the Arizona Department of Environmental Quality’s water-quality standards for aquatic and wildlife uses, and all bacteria levels were below the Arizona Department of Environmental Quality’s recommended recreational water-quality criteria. Three out of 81 pesticides were detected in the water samples.Trace-element concentrations in bed sediment were relatively consistent between the inlet, middle, and outlet locations. Lead, manganese, nickel, and zinc concentrations, however, decreased from the inlet to outlet locations. Concentrations for lead, nickel, and zinc in some bed-sediment samples exceeded consensus-based sediment-quality guidelines probable effect concentrations. Eleven out of 61 halogenated compounds were detected in bed sediment at the inlet location, whereas three were detected at the middle location, and five were detected at the outlet location. No methylmercury was detected in bed sediment. Total mercury was detected in bed sediment at concentrations below the consensus-based sediment-quality guidelines probable effect concentration.Sixteen trace elements were detected in at least one of the fish-tissue samples, and trace-element concentrations were relatively consistent between the three fish-tissue samples. Seven halogenated compounds were detected in at least one of the whole-body fish samples; four to five compounds were detected in each fish. One fish-tissue sample exceeded the U.S. Environmental Protection Agency human health consumption criteria for methylmercury.

11beta-Hydroxysteroid dehydrogenase Type 1: genetic polymorphisms are associated with Type 2 diabetes in Pima Indians independently of obesity and expression in adipocyte and muscle.

PubMed

Nair, S; Lee, Y H; Lindsay, R S; Walker, B R; Tataranni, P A; Bogardus, C; Baier, L J; Permana, P A

2004-06-01

The enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) modulates tissue-specific glucocorticoid concentrations by generating active cortisol. We have shown that adipose tissue 11beta-HSD1 mRNA levels were associated with adiposity and insulinaemia. Here we conducted further expression and genetic association studies in Pima Indians. The 11beta-HSD1 mRNA concentrations were measured in abdominal subcutaneous adipocytes (n=61) and skeletal muscle tissues (n=64). Single nucleotide polymorphisms in the HSD11B1 gene were genotyped in a larger group of full-blooded Pima Indians. Two representative SNPs (SNP1, n=706; SNP5, n=839) were associated with Type 2 diabetes mellitus (p=0.01), although neither SNP was associated with obesity. Among subjects with normal glucose tolerance, SNP1 (n=127) and SNP5 (n=159) were associated with insulin-mediated glucose uptake rates (p=0.03 and p=0.04), and SNP1 was further associated with fasting, 30-min, and 2-h plasma insulin concentrations (p=0.002, p=0.002 and p=0.03). Adipocyte 11beta-HSD1 mRNA concentrations were correlated positively with adiposity and insulinaemia, and were additionally negatively correlated with insulin-mediated glucose uptake rates; nevertheless, the adipocyte 11beta-HSD1 expression did not correlate with genotypes of the donors. The muscle 11beta-HSD1 mRNA concentrations did not correlate with any anthropometric or metabolic variables. We confirmed that adipocyte 11beta-HSD1 mRNA concentrations were associated with adiposity, and showed that genetic variations in the HSD11B1 gene were associated with Type 2 diabetes mellitus, plasma insulin concentrations and insulin action, independent of obesity. The variable adipose expression might not be a primary consequence of these HSD11B1 SNPs. Therefore, it is possible that the HSD11B1 gene is under tissue-specific regulation, and has tissue-specific consequences.

Water-quality data for Smith and Bybee Lakes, Portland, Oregon, June to November, 1982

USGS Publications Warehouse

Clifton, Daphne G.

1983-01-01

Water-quality monitoring at Smith and Bybee Lakes included measurement of water temperature, dissolved oxygen concentration and percent saturation, pH, specific conductance, lake depth, alkalinity, dissolved carbon, total dissolved solids, secchi disk light transparency, nutrients, and chlorophyll a and b. In addition, phytoplankton, zooplankton, and benthic invertebrate populations were identified and enumerated. Lakebed sediment was analyzed for particle size, volatile solids, immediate oxygen demand, trace metals, total organic carbon, nutrients, and organic constituents. (USGS)

Investigation of "mysterious" disease in livestock: hydrocyanic acid poisoning.

PubMed

Krishna, L; Katoch, R C

1989-12-01

An investigation of "mysterious" disease due to hydrocyanic acid (HCN) poisoning in livestock in this state was carried out. Detailed clinicopathological and pathological studies were conducted. Characteristic signs of acute tympany followed with profuse frothing, convulsions and dyspnea were recorded. Cynosis of the mucosa with characteristic anoxemic tissue changes and a high concentration of HCN in rumen content, feed and skeletal muscles were recorded. These were sufficient to establish the diagnosis. Successful treatment with a specific antidote was achieved, and further morbidity and mortality was checked.

Electronic Tongue Containing Redox and Conductivity Sensors

NASA Technical Reports Server (NTRS)

Buehler, Martin

2007-01-01

The Electronic Tongue (E-tongue 2) is an assembly of sensors for measuring concentrations of metal ions and possibly other contaminants in water. Potential uses for electronic tongues include monitoring the chemical quality of water in a variety of natural, industrial, and laboratory settings, and detecting micro-organisms indirectly by measuring microbially influenced corrosion. The device includes a heater, a temperature sensor, an oxidation/reduction (redox) sensor pair, an electrical sensor, an array of eight galvanic cells, and eight ion-specific electrodes.

Quality-of-water data and statistical summary for selected coal-mined strip pits in Crawford and Cherokee counties, southeastern Kansas

USGS Publications Warehouse

Pope, Larry M.; Diaz, A.M.

1982-01-01

Quality-of-water data, collected October 21-23, 1980, and a statistical summary are presented for 42 coal-mined strip pits in Crawford and Cherokee Counties, Southeastern Kansas. The statistical summary includes minimum and maximum observed values , mean, and standard deviation. Simple linear regression equations relating specific conductance, dissolved solids, and acidity to concentrations of dissolved solids, sulfate, calcium, and magnesium, potassium, aluminum, and iron are also presented. (USGS)

Solar Technology Validation Project - USS Data, LLC: Cooperative Research and Development Final Report, CRADA Number CRD-09-367-04

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilcox, S.

2013-08-01

Under this Agreement, NREL will work with Participant to improve concentrating solar power system performance characterizations. This work includes, but is not limited to, research and development of methods for acquiring renewable resource characterization information using site-specific measurements of solar radiation and meteorological conditions; collecting system performance data; and developing tools for improving the design, installation, operation, and maintenance of solar energy conversion systems. This work will be conducted at NREL and Participant facilities.

Solar Technology Validation Project - RES Americas: Cooperative Research and Development Final Report, CRADA Number CRD-09-367-11

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilcox, S.

Under this Agreement, NREL will work with Participant to improve concentrating solar power system performance characterizations. This work includes, but is not limited to, research and development of methods for acquiring renewable resource characterization information using site-specific measurements of solar radiation and meteorological conditions; collecting system performance data; and developing tools for improving the design, installation, operation, and maintenance of solar energy conversion systems. This work will be conducted at NREL and Participant facilities.

Partitioning of total mercury and methylmercury to the colloidal phase in freshwaters.

PubMed

Babiarz, C L; Hurley, J P; Hoffmann, S R; Andren, A W; Shafer, M M; Armstrong, D E

2001-12-15

Using tangential flow ultrafiltration, total mercury (HgT) and methylmercury (MeHg) concentrations in the colloidal phase (0.4 microm-10 kDa) were determined for 15 freshwaters located in the upper Midwest (Minnesota, Michigan, and Wisconsin) and the Southern United States (Georgia and Florida). Unfiltered concentrations were typical of those reported for freshwater and ranged from 0.9 to 27.1 ng L(-1) HgT and from 0.08 to 0.86 ng L(-1) MeHg. For some rivers, HgT and MeHg in the colloidal phase comprised up to 72% of the respective unfiltered concentration. On average, however, HgT and MeHg concentrations were evenly distributed between the particulate (>0.4 microm), colloidal, and dissolved (<10 kDa) phases. The pool of Hg in the colloidal phase decreased with increasing specific conductance. Results from experiments on freshwaters with artificially elevated specific conductance suggest that HgT and MeHg may partition to different subfractions of colloidal material. The colloidal-phase HgT correlation with filtered organic carbon (OC(F)) was generally poor (r2 < 0.14; p > 0.07), but the regression of MeHg with OC(F) was strong, especially in the upper Midwest (r2 = 0.78; p < 0.01). On a mass basis, colloidal-phase Hg concentrations were similar to those of unimpacted sediments in the Midwest. Mercury to carbon ratios averaged 352 pg of HgT/mg of C and 25 pg of MeHg/mg of C and were not correlated to ionic strength. The log of the partition coefficient (log K(D)) for HgT and MeHg ranged from 3.7 to 6.4 and was typical of freshwater values determined using a 0.4 microm cutoff between the particulate phase and the dissolved phase. Log K(D) calculated using the <10 kDa fraction as "dissolved" ranged from 4.3 to 6.6 and had a smaller standard deviation about the mean. In addition, our data support the "particle concentration effect" (PCE) hypothesis that the association of Hg with colloids in the filter-passing fraction can lower the observed log K(D). The similarity between colloidal and particulate-phase partition coefficients suggests that colloidal mass and not preferential colloidal partitioning drives the PCE.

Cs sorption to potential host rock of low-level radioactive waste repository in Taiwan: experiments and numerical fitting study.

PubMed

Wang, Tsing-Hai; Chen, Chin-Lung; Ou, Lu-Yen; Wei, Yuan-Yaw; Chang, Fu-Lin; Teng, Shi-Ping

2011-09-15

A reliable performance assessment of radioactive waste repository depends on better knowledge of interactions between nuclides and geological substances. Numerical fitting of acquired experimental results by the surface complexation model enables us to interpret sorption behavior at molecular scale and thus to build a solid basis for simulation study. A lack of consensus on a standard set of assessment criteria (such as determination of sorption site concentration, reaction formula) during numerical fitting, on the other hand, makes lower case comparison between various studies difficult. In this study we explored the sorption of cesium to argillite by conducting experiments under different pH and solid/liquid ratio (s/l) with two specific initial Cs concentrations (100mg/L, 7.5 × 10(-4)mol/L and 0.01 mg/L, 7.5 × 10(-8)mol/L). After this, numerical fitting was performed, focusing on assessment criteria and their consequences. It was found that both ion exchange and electrostatic interactions governed Cs sorption on argillite. At higher initial Cs concentration the Cs sorption showed an increasing dependence on pH as the solid/liquid ratio was lowered. In contrast at trace Cs levels, the Cs sorption was neither s/l dependent nor pH sensitive. It is therefore proposed that ion exchange mechanism dominates Cs sorption when the concentration of surface sorption site exceeds that of Cs, whereas surface complexation is attributed to Cs uptake under alkaline environments. Numerical fitting was conducted using two different strategies to determine concentration of surface sorption sites: the clay model (based on the cation exchange capacity plus surface titration results) and the iron oxide model (where the concentration of sorption sites is proportional to the surface area of argillite). It was found that the clay model led to better fitting than the iron oxide model, which is attributed to more amenable sorption sites (two specific sorption sites along with larger site density) when using clay model. Moreover, increasing s/l ratio would produce more sorption sites, which helps to suppress the impact of heterogeneous surface on Cs sorption behavior under high pH environments. Copyright © 2011 Elsevier B.V. All rights reserved.

Transport properties of alumina nanofluids.

PubMed

Wong, Kau-Fui Vincent; Kurma, Tarun

2008-08-27

Recent studies have showed that nanofluids have significantly greater thermal conductivity compared to their base fluids. Large surface area to volume ratio and certain effects of Brownian motion of nanoparticles are believed to be the main factors for the significant increase in the thermal conductivity of nanofluids. In this paper all three transport properties, namely thermal conductivity, electrical conductivity and viscosity, were studied for alumina nanofluid (aluminum oxide nanoparticles in water). Experiments were performed both as a function of volumetric concentration (3-8%) and temperature (2-50 °C). Alumina nanoparticles with a mean diameter of 36 nm were dispersed in water. The effect of particle size was not studied. The transient hot wire method as described by Nagaska and Nagashima for electrically conducting fluids was used to test the thermal conductivity. In this work, an insulated platinum wire of 0.003 inch diameter was used. Initial calibration was performed using de-ionized water and the resulting data was within 2.5% of standard thermal conductivity values for water. The thermal conductivity of alumina nanofluid increased with both increase in temperature and concentration. A maximum thermal conductivity of 0.7351 W m(-1) K(-1) was recorded for an 8.47% volume concentration of alumina nanoparticles at 46.6 °C. The effective thermal conductivity at this concentration and temperature was observed to be 1.1501, which translates to an increase in thermal conductivity by 22% when compared to water at room temperature. Alumina being a good conductor of electricity, alumina nanofluid displays an increasing trend in electrical conductivity as volumetric concentration increases. A microprocessor-based conductivity/TDS meter was used to perform the electrical conductivity experiments. After carefully calibrating the conductivity meter's glass probe with platinum tip, using a standard potassium chloride solution, readings were taken at various volumetric concentrations. A 3457.1% increase in the electrical conductivity was measured for a small 1.44% volumetric concentration of alumina nanoparticles in water. The highest value of electrical conductivity, 314 µS cm(-1), was recorded for a volumetric concentration of 8.47%. In the determination of the kinematic viscosity of alumina nanofluid, a standard kinematic viscometer with constant temperature bath was used. Calibrated capillary viscometers were used to measure flow under gravity at precisely controlled temperatures. The capillary viscometers were calibrated with de-ionized water at different temperatures, and the resulting kinematic viscosity values were found to be within 3% of the standard published values. An increase of 35.5% in the kinematic viscosity was observed for an 8.47% volumetric concentration of alumina nanoparticles in water. The maximum kinematic viscosity of alumina nanofluid, 2.901 42 mm(2) s(-1), was obtained at 0 °C for an 8.47% volumetric concentration of alumina nanoparticles. The experimental results of the present work will help researchers arrive at better theoretical models.

Combined interpretation of radar, hydraulic, and tracer data from a fractured-rock aquifer near Mirror Lake, New Hampshire, USA

USGS Publications Warehouse

Day-Lewis, F. D.; Lane, J.W.; Gorelick, S.M.

2006-01-01

An integrated interpretation of field experimental cross-hole radar, tracer, and hydraulic data demonstrates the value of combining time-lapse geophysical monitoring with conventional hydrologic measurements for improved characterization of a fractured-rock aquifer. Time-lapse difference-attenuation radar tomography was conducted during saline tracer experiments at the US Geological Survey Fractured Rock Hydrology Research Site near Mirror Lake, Grafton County, New Hampshire, USA. The presence of electrically conductive saline tracer effectively illuminates permeable fractures or pathways for geophysical imaging. The geophysical results guide the construction of three-dimensional numerical models of ground-water flow and solute transport. In an effort to explore alternative explanations for the tracer and tomographic data, a suite of conceptual models involving heterogeneous hydraulic conductivity fields and rate-limited mass transfer are considered. Calibration data include tracer concentrations, the arrival time of peak concentration at the outlet, and steady-state hydraulic head. Results from the coupled inversion procedure suggest that much of the tracer mass migrated outside the three tomographic image planes, and that solute is likely transported by two pathways through the system. This work provides basic and site-specific insights into the control of permeability heterogeneity on ground-water flow and solute transport in fractured rock. ?? Springer-Verlag 2004.

Computational Fluid Dynamics Modeling of Bacillus anthracis ...

EPA Pesticide Factsheets

Journal Article Three-dimensional computational fluid dynamics and Lagrangian particle deposition models were developed to compare the deposition of aerosolized Bacillus anthracis spores in the respiratory airways of a human with that of the rabbit, a species commonly used in the study of anthrax disease. The respiratory airway geometries for each species were derived from computed tomography (CT) or µCT images. Both models encompassed airways that extended from the external nose to the lung with a total of 272 outlets in the human model and 2878 outlets in the rabbit model. All simulations of spore deposition were conducted under transient, inhalation-exhalation breathing conditions using average species-specific minute volumes. Four different exposure scenarios were modeled in the rabbit based upon experimental inhalation studies. For comparison, human simulations were conducted at the highest exposure concentration used during the rabbit experimental exposures. Results demonstrated that regional spore deposition patterns were sensitive to airway geometry and ventilation profiles. Despite the complex airway geometries in the rabbit nose, higher spore deposition efficiency was predicted in the upper conducting airways of the human at the same air concentration of anthrax spores. This greater deposition of spores in the upper airways in the human resulted in lower penetration and deposition in the tracheobronchial airways and the deep lung than that predict

Optimization of Exopolysaccharide Production by Lactobacillus delbrueckii subsp. bulgaricus RR Grown in a Semidefined Medium

PubMed Central

Kimmel, Stacy A.; Roberts, Robert F.; Ziegler, Gregory R.

1998-01-01

The optimal fermentation temperature, pH, and Bacto-casitone (Difco Laboratories, Detroit, Mich.) concentration for production of exopolysaccharide by Lactobacillus delbrueckii subsp. bulgaricus RR in a semidefined medium were determined by using response surface methods. The design consisted of 20 experiments, 15 unique combinations, and five replications. All fermentations were conducted in a fermentor with a 2.5-liter working volume and were terminated when 90% of the glucose in the medium had been consumed. The population of L. delbrueckii subsp. bulgaricus RR and exopolysaccharide content were measured at the end of each fermentation. The optimum temperature, pH, and Bacto-casitone concentration for exopolysaccharide production were 38°C, 5, and 30 g/liter, respectively, with a predicted yield of 295 mg of exopolysaccharide/liter. The actual yield under these conditions was 354 mg of exopolysaccharide/liter, which was within the 95% confidence interval (217 to 374 mg of exopolysaccharide/liter). An additional experiment conducted under optimum conditions showed that exopolysaccharide production was growth associated, with a specific production at the endpoint of 101.4 mg/g of dry cells. Finally, to obtain material for further characterization, a 100-liter fermentation was conducted under optimum conditions. Twenty-nine grams of exopolysaccharide was isolated from centrifuged, ultrafiltered fermentation broth by ethanol precipitation. PMID:9464404

Application of electromagnetic techniques in survey of contaminated groundwater at an abandoned mine complex in southwestern Indiana, U.S.A.

USGS Publications Warehouse

Brooks, G.A.; Olyphant, G.A.; Harper, D.

1991-01-01

In part of a large abandoned mining complex, electromagnetic geophysical surveys were used along with data derived from cores and monitoring wells to infer sources of contamination and subsurface hydrologic connections between acidic refuse deposits and adjacent undisturbed geologic materials. Electrical resistivity increases sharply along the boundary of an elevated deposit of pyritic coarse refuse, which is highly contaminated and electrically conductive, indicating poor subsurface hydrologic connections with surrounding deposits of fine refuse and undisturbed glacial material. Groundwater chemistry, as reflected in values of specific conductance, also differs markedly across the deposit's boundary, indicating that a widespread contaminant plume has not developed around the coarse refuse in more than 40 yr since the deposit was created. Most acidic drainage from the coarse refuse is by surface runoff and is concentrated around stream channels. Although most of the contaminated groundwater within the study area is concentrated within the surficial refuse deposits, transects of apparent resistivity and phase angle indicate the existence of an anomalous conductive layer at depth (>4 m) in thick alluvial sediments along the northern boundary of the mining complex. Based on knowledge of local geology, the anomaly is interpreted to represent a subsurface connection between the alluvium and a flooded abandoned underground mine. ?? 1991 Springer-Verlag New York Inc.

Application of electromagnetic techniques in survey of contaminated groundwater at an abandoned mine complex in southwestern Indiana, U.S.A.

NASA Astrophysics Data System (ADS)

Brooks, Glenn A.; Olyphant, Greg A.; Harper, Denver

1991-07-01

In part of a large abandoned mining complex, electromagnetic geophysical surveys were used along with data derived from cores and monitoring wells to infer sources of contamination and subsurface hydrologic connections between acidic refuse deposits and adjacent undisturbed geologic materials. Electrical resistivity increases sharply along the boundary of an elevated deposit of pyritic coarse refuse, which is highly contaminated and electrically conductive, indicating poor subsurface hydrologic connections with surrounding deposits of fine refuse and undisturbed glacial material. Groundwater chemistry, as reflected in values of specific conductance, also differs markedly across the deposit's boundary, indicating that a widespread contaminant plume has not developed around the coarse refuse in more than 40 yr since the deposit was created. Most acidic drainage from the coarse refuse is by surface runoff and is concentrated around stream channels. Although most of the contaminated groundwater within the study area is concentrated within the surficial refuse deposits, transects of apparent resistivity and phase angle indicate the existence of an anomalous conductive layer at depth (>4 m) in thick alluvial sediments along the northern boundary of the mining complex. Based on knowledge of local geology, the anomaly is interpreted to represent a subsurface connection between the alluvium and a flooded abandoned underground mine.

Complex conductivity response to silver nanoparticles in ...

EPA Pesticide Factsheets

The increase in the use of nanoscale materials in consumer products has resulted in a growing concern of their potential hazard to ecosystems and public health from their accidental or intentional introduction to the environment. Key environmental, health, and safety research needs include knowledge and methods for their detection, characterization, fate, and transport. Specifically, techniques available for the direct detection and quantification of their fate and transport in the environment are limited. Their small size, high surface area to volume ratio, interfacial, and electrical properties make metallic nanoparticles, such as silver nanoparticles, good targets for detection using electrical geophysical techniques. Here we measured the complex conductivity response to silver nanoparticles in sand columns under varying moisture conditions (0–30%), nanoparticle concentrations (0–10 mg/g), lithology (presence of clay), pore water salinity (0.0275 and 0.1000 S/m), and particle size (35, 90–210 and 1500–2500 nm). Based on the Cole-Cole relaxation models we obtained the chargeability and the time constant. We demonstrate that complex conductivity can detect silver nanoparticles in porous media with the response enhanced by higher concentrations of silver nanoparticles, moisture content, ionic strength, clay content and particle diameter. Quantification of the volumetric silver nanoparticles content in the porous media can also be obtained from complex co

Geographic patterns of hepatocellular carcinoma mortality with exposure to iron in groundwater in Taiwanese population: An ecological study

PubMed Central

2013-01-01

Background Many studies have examined the risk factors for HCC (including hepatitis B virus, hepatitis C virus, aflatoxin, retinol, cigarette smoking, and alcohol consumption). However, data from previous studies on the association between iron exposure, land subsidence, and HCC mortality/incidence were limited, especially in Taiwanese population. We aimed to explore the geographical distribution of HCC mortality rates by township-specific data and to evaluate the association between HCC mortality, land subsidence, and iron levels in groundwater in Taiwan. Methods We conducted an ecological study and calculated the HCC age-standardized mortality/incidence rates according to death certificates issued in Taiwan from 1992 to 2001 and incidence data from 1995–1998. The land subsidence dataset before 2005 and iron concentrations in groundwater in 1989 are also involved in this study. Both geographical information systems and Pearson correlation coefficients were used to analyze the relationship between HCC mortality rates, land subsidence, and iron concentrations in groundwater. Results Township-specific HCC mortality rates are higher in southwestern coastal townships where serious land subsidence and higher township-specific concentrations of iron in groundwater are present. The Pearson correlation coefficients of iron concentrations in groundwater and ASRs of HCC were 0.286 (P = 0.004) in males and 0.192 (P = 0.058) in females for mortality data; the coefficients were 0.375 (P < 0.001) in males and 0.210 (P = 0.038) in females for incidence data. Conclusions This study showed that HCC mortality is clustered in southwestern Taiwan and the association with the iron levels in groundwater in Taiwanese population warrant further investigation. PMID:23590585

Domain specific effects of postnatal toenail methylmercury exposure on child behaviour.

PubMed

Karatela, Shamshad; Paterson, Janis; Ward, Neil I

2017-05-01

Very little is known about the relationship between postnatal methylmercury concentrations (via toenails as bioindicator) and behavioural characteristics of Pacific Island children living in New Zealand. The aim of this study was to explore the association between total mercury exposure and different domains of behavioural problems in Pacific children. A sample of nine-year-old Pacific Island children resident in Auckland, New Zealand participated in this study. Total mercury was determined in biological samples (toenail clippings) on behavioural problems as identified by mothers (using the child behaviour checklist). Specific behavioural domains, particularly aggression, rule breaking, attention and social problems were studied in relation to mercury exposure using toenails. The determination of mercury concentration in toenail clippings, after acid digestion was carried out using inductively coupled plasma mass spectrometry. The observational study was conducted between July 2010 and July 2011 in which 278 eligible nine-year-old Pacific Island children were enrolled (Girls n=58%; boys n=42%). showed that 21% of the children had total toenail mercury concentrations (1.5μg/g to 6μg/g) higher than the United State Environmental Protection Agency recommended levels (RfD; 1μg/g Hg) for optimal health in children. Aggressive behaviour was associated with total toenail mercury exposure after adjusting for gender, ethnicity and income levels (OR: 2.15 95% CI 1.45, 3.18 p-value <0.05; OR 1.38 95% CI 0.83, 1.2 p value <0.05, respectively). Overall, this research contributes to the understanding of total toenail mercury concentrations for Pacific people in New Zealand using toenail clippings as biomarkers in terms of associations with child behavioural problems. Mercury in toenails demonstrated a moderate association with a specific behavioural domain - aggressive behaviour. Copyright © 2017 Elsevier GmbH. All rights reserved.

Correlation of quantitative PCR for a poultry-specific brevibacterium marker gene with bacterial and chemical indicators of water pollution in a watershed impacted by land application of poultry litter.

PubMed

Weidhaas, Jennifer L; Macbeth, Tamzen W; Olsen, Roger L; Harwood, Valerie J

2011-03-01

The impact of fecal contamination from human and agricultural animal waste on water quality is a major public health concern. Identification of the dominant source(s) of fecal pollution in a watershed is necessary for assessing the safety of recreational water and protecting water resources. A field study was conducted using quantitative PCR (qPCR) for the 16S rRNA gene of Brevibacterium sp. LA35 to track feces-contaminated poultry litter in environmental samples. Based on sensitivity and specificity characteristics of the qPCR method, the Bayesian conditional probability that detection of the LA35 marker gene in a water sample represented a true-positive result was 93%. The marker's covariance with fecal indicator bacteria (FIB) and metals associated with poultry litter was also assessed in litter, runoff, surface water, and groundwater samples. LA35 was detected in water and soil samples collected throughout the watershed, and its concentration covaried with concentrations of Escherichia coli, enterococci, As, Cu, P, and Zn. Significantly greater concentrations of FIB, As, Cu, P, and Zn were observed in edge-of-field runoff samples in which LA35 was detected, compared to samples in which it was not detected. Furthermore, As, Cu, P, and Zn concentrations covaried in environmental samples in which LA35 was detected and typically did not in samples in which the marker gene was not detected. The covariance of the poultry-specific LA35 marker gene with these known contaminants from poultry feces provides further evidence that it is a useful tool for assessing the impact of poultry-derived fecal pollution in environmental waters.

Behaviour of conductivity improvers in jet fuel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dacre, B.; Hetherington, J.I.

1995-05-01

Dangerous accumulation of electrostatic charge can occur due to high speed pumping and microfiltration of fuel. This can be avoided by increasing the electrical conductivity of the fuel using conductivity improver additives. However, marked variations occur in the conductivity response of different fuels when doped to the same level with conductivity improver. This has been attributed to interactions of the conductivity improver with other fuel additives or fuel contaminants. The present work concentrates on the effects of fuel contaminants, in particular polar compounds, on the performance of the conductivity improver. Conductivity is the fuel property of prime interest. The conductivitymore » response of model systems of the conductivity improver STADIS 450 in dodecane has been measured and the effect on this conductivity of additions of model polar contaminants sodium naphthenate, sodium dodecyl benzene sulphonate, and sodium phenate have been measured. The sodium salts have been found to have a complex effect on the performance of STADIS 450, reducing the conductivity at low concentrations to a minimum value and then increasing the conductivity at high concentrations of sodium salts. This work has focused on characterising this minimum in the conductivity values and on understanding the reason for its occurrence. The effects on the minimum conductivity value of the following parameters are investigated: (a) time, (b) STADIS 450 concentration, (c) sodium salt concentration, (d) mixed sodium salts, (e) experimental method, (f) a phenol, (g) individual components of STADIS 450. The complex conductivity response of the STADIS 450 to sodium salt impurities is discussed in terms of possible inter-molecular interactions.« less

Isolation, identification and growth determination of lactic acid-utilizing yeasts from the ruminal fluid of dairy cattle.

PubMed

Sirisan, V; Pattarajinda, V; Vichitphan, K; Leesing, R

2013-08-01

Ruminal organic acid production, especially lactic acid, can be modified by feeding cattle highly concentrated diets, which have been shown to adversely affect dairy cattle health. Therefore, the use of lactic acid-utilizing organisms is considered to be a potential method for controlling lactic acid levels. This study was conducted to isolate and identify lactic acid-utilizing yeasts from the ruminal fluid of dairy cattle and to determine the specific growth rate and generation time when using lactic acid as a carbon source instead of glucose. Seventeen yeast isolates were examined in this study. Yeasts isolated from dairy cattle that were fed a high cassava pulp diet (HCP) had higher specific growth rates and shorter generation times than yeasts isolated from dairy cattle that were fed a high-concentrate diet (HC) and a mixed diet (M). The three most effective yeasts in terms of specific growth rate and generation time were Pichia kudriavzevii, Candida rugosa and Kodamaea ohmeri, with 99, 100 and 99% nucleotide identities, respectively. These three isolates could be used as potential probiotics in dairy cattle diets. This study demonstrates that yeasts isolated from the ruminal fluid of dairy cattle can utilize lactic acid as a carbon and energy source for growth. The isolated yeasts can be used as probiotic supplements for dairy cattle that are fed highly concentrated diets to reduce ruminal lactic acid production. © 2013 The Society for Applied Microbiology.

Human health risk assessment of lead from mining activities at semi-arid locations in the context of total lead exposure.

PubMed

Zheng, Jiajia; Huynh, Trang; Gasparon, Massimo; Ng, Jack; Noller, Barry

2013-12-01

Lead from historical mining and mineral processing activities may pose potential human health risks if materials with high concentrations of bioavailable lead minerals are released to the environment. Since the Joint Expert Committee on Food Additives of Food and Agriculture Organization/World Health Organization withdrew the Provisional Tolerable Weekly Intake of lead in 2011, an alternative method was required for lead exposure assessment. This study evaluated the potential lead hazard to young children (0-7 years) from a historical mining location at a semi-arid area using the U.S. EPA Integrated Exposure Uptake Biokinetic (IEUBK) Model, with selected site-specific input data. This study assessed lead exposure via the inhalation pathway for children living in a location affected by lead mining activities and with specific reference to semi-arid conditions and made comparison with the ingestion pathway by using the physiologically based extraction test for gastro-intestinal simulation. Sensitivity analysis for major IEUBK input parameters was conducted. Three groups of input parameters were classified according to the results of predicted blood concentrations. The modelled lead absorption attributed to the inhalation route was lower than 2 % (mean ± SE, 0.9 % ± 0.1 %) of all lead intake routes and was demonstrated as a less significant exposure pathway to children's blood, compared with ingestion. Whilst dermal exposure was negligible, diet and ingestion of soil and dust were the dominant parameters in terms of children's blood lead prediction. The exposure assessment identified the changing role of dietary intake when house lead loadings varied. Recommendations were also made to conduct comprehensive site-specific human health risk assessment in future studies of lead exposure under a semi-arid climate.

Appraisal of water-quality conditions, lower Black River, Windsor County, Vermont

USGS Publications Warehouse

Toppin, K.W.

1983-01-01

Six hydroelectric power dams are planned along a 22-mile reach of the lower Black River in southeastern Windsor County, Vermont. Data were collected at 10 stations, during water years 1977-81, to appraise quality conditions before construction. Average specific conductance of Black River is 101 micromhos indicating low concentrations of dissolved solids. Concentrations of common constituents and minor elements were generally low and within safe levels for aquatic life. Near-saturated dissolved oxygen concentrations and relatively low mean total organic carbon concentrations indicate little oxygen-consuming substances in Black River. Mean total nitrogen concentrations ranged from 0.31 mg/L (milligrams per liter) to 0.61 mg/L. The highest concentrations were most likely due to secondary waste discharges entering the river. Nitrate was the primary form of inorganic nitrogen, mean concentrations ranged from 0.13 to 0.27 mg/L. Concentrations seem high enough to promote excessive algal growth in the proposed Hawks Mountain Reservoir. Mean concentrations of total phosphorus ranged from 0.014 to 0.112 mg/L as P. Maximum concentrations at all stations generally exceeded U.S. Environmental Protection Agency suggested levels for water entering lakes and reservoirs. Mean orthophosphorus concentrations ranged from 0.005 to 0.029 mg/L, suggesting a potential for nuisance algal conditions to develop in the proposed reservoir. Mean algal growth potential concentrations ranged from 1.3 to 8.8 mg/L, falling within the moderately high to high productivity range. No pesticides and polychlorinated biphenyls were detected. (USGS)

Elucidation of band structure of charge storage in conducting polymers using a redox reaction.

PubMed

Contractor, Asfiya Q; Juvekar, Vinay A

2014-07-01

A novel technique to investigate charge storage characteristics of intrinsically conducting polymer films has been developed. A redox reaction is conducted on a polymer film on a rotating disk electrode under potentiostatic condition so that the rate of charging of the film equals the rate of removal of the charge by the reaction. The voltammogram obtained from the experiment on polyaniline film using Fe(2+)/Fe(3+) in HCl as the redox system shows five distinct linear segments (bands) with discontinuity in the slope at specific transition potentials. These bands are the same as those indicated by electron spin resonance (ESR)/Raman spectroscopy with comparable transition potentials. From the dependence of the slopes of the bands on concentration of ferrous and ferric ions, it was possible to estimate the energies of the charge carriers in different bands. The film behaves as a redox capacitor and does not offer resistance to charge transfer and electronic conduction.

Formation of transformation products from wastewater-derived pharmaceuticals in an urban lowland stream

NASA Astrophysics Data System (ADS)

Jäger, A.; Posselt, M.; Schaper, J. L.; Lewandowski, J.

2017-12-01

Not only transport, but especially transformation of polar organic micropollutants in urban streams is of increasing concern for urban water management. While concentrations of pharmaceuticals might decrease down the river, concentrations of their more persistent metabolites potentially increase due to microbial transformation. The river Erpe, an urban lowland stream located in Berlin, Germany, receives high loads of treated waste water. A Lagrangian sampling scheme was applied to follow water parcels 4.7 km down the river using the diurnal fluctuations of electrical conductivity as an intrinsic conservative tracer. Each experiment comprised of hourly sample collection for two days, accompanied by discharge measurements and continuous data logging of electrical conductivity. The fate of pharmaceuticals and their transformation products was compared between seasons (April and June) and before and after a stretch of the river has been cleared of macrophytes. The set of micropollutants was analysed by a newly developed direct injection-UHPLC-MS/MS method. The behaviour of individual micropollutants was compound-specific. Valsartan and metoprolol were attenuated by up to 18% of their original concentration. At the same time the transformation products valsartan acid and metoprolol acid increased in concentration by up to 24%. Their formation along the reach varied between seasons and was influenced by macrophyte removal. The findings indicate that the self-purification capacity of urban rivers is variable in time and sensitive to changes in the river's hydrological regime and emphasize the relevance of formation of transformation products in urban rivers.

Quality of ground water in the Puget sound region, Washington, 1981

USGS Publications Warehouse

Turney, G.L.

1986-01-01

Groundwater from more than 100 sites in the Puget Sound region, Washington, was sampled and analyzed in 1981 for pH, specific conductance, and concentrations of fecal coliform bacteria, major ions, and dissolved iron, manganese, and nitrate. 20% of the samples were analyzed for concentrations of dissolved trace metals including aluminum, arsenic, barium, cadmium, chromium, copper, lead, mercury, selenium, silver, and zinc. The predominant water types were calcium bicarbonate and calcium-magnesium bicarbonate. Some wells in San Juan and Island Counties contained sodium chloride as a result of seawater intrusion. Dissolved solids concentrations were generally < 150 mg/L. Iron concentrations > 300 micrograms/L in 14% of all samples. Manganese concentrations > 50 micrograms/L in 40% of all samples. Trace-metal concentrations were generally < 10 mg/L , except for barium, copper, lead, and zinc. Nitrate concentrations were < 1.0 mg/L in water for over 75% of the sites. Concentrations > 1.0 mg/L in samples from Skagit, Whatcom , and Pierce Counties, were probably due to agricultural activities or septic tanks. Fecal coliform bacteria were detected in isolated instances. EPA drinking water regulations were exceeded only in isolated instances, except for widespread excessive iron and manganese concentrations. The historical data for the region were also evaluated for the same constituents. There are quantitative differences between historical and 1981 data, but they may be due to inconsistencies in data collection and analytical methods. (Author 's abstract)

Topotactic Metal-Insulator Transition in Epitaxial SrFeO x Thin Films

DOE PAGES

Khare, Amit; Shin, Dongwon; Yoo, Tae Sup; ...

2017-07-31

Multivalent transition metal oxides provide fascinating and rich physics related to oxygen stoichiometry. In particular, the adoptability of various valence states of transition metals enables perovskite oxides to display mixed (oxygen) ionic and electronic conduction and catalytic activity useful in many practical applications, including solid-oxide fuel cells (SOFCs), rechargeable batteries, gas sensors, and memristive devices. For proper realization of the ionic conduction and catalytic activity, it is essential to understand the reversible oxidation and reduction process, which is governed by oxygen storage/release steps in oxides. Topotactic phase transformation facilitates the redox process in perovskites with specific oxygen vacancy ordering bymore » largely varying the oxygen concentration of a material without losing the lattice framework. The concentration and diffusion of oxide ions (O 2–), the valence state of the transition metal cations, and the thermodynamic structural integrity together provide fundamental understanding and ways to explicitly control the redox reaction.[6] In addition, it offers an attractive route for tuning the emergent physical properties of transition metal oxides, via strong coupling between the crystal lattice and electronic structure.« less

Ion Dynamics in a Mixed-Cation Alkoxy-Ammonium Ionic Liquid Electrolyte for Sodium Device Applications.

PubMed

Pope, Cameron R; Kar, Mega; MacFarlane, Douglas R; Armand, Michel; Forsyth, Maria; O'Dell, Luke A

2016-10-18

The ion dynamics in a novel sodium-containing room-temperature ionic liquid (IL) consisting of an ether-functionalised quaternary ammonium cation and bis(trifluoromethylsulfonyl)amide [NTf 2 ] anion with various concentrations of Na[NTf 2 ] have been characterised using differential scanning calorimetry, impedance spectroscopy, diffusometry and NMR relaxation measurements. The IL studied has been specifically designed to dissolve a relatively large concentration of Na[NTf 2 ] salt (over 2 mol kg -1 ) as this has been shown to improve ion transport and conductivity. Consistent with other studies, the measured ionic conductivity and diffusion coefficients show that the overall ionic mobility decreases with decreasing temperature and increasing salt content. NMR relaxation measurements provide evidence for correlated dynamics between the ether-functionalised ammonium and Na cations, possibly with the latter species acting as cross-links between multiple ammonium cations. Finally, preliminary cyclic voltammetry experiments show that this IL can undergo stable electrochemical cycling and could therefore be potentially useful as an electrolyte in a Na-based device. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Can electrocoagulation process be an appropriate technology for phosphorus removal from municipal wastewater?

PubMed

Nguyen, D Duc; Ngo, H Hao; Guo, W; Nguyen, T Thanh; Chang, Soon W; Jang, A; Yoon, Yong S

2016-09-01

This paper evaluated a novel pilot scale electrocoagulation (EC) system for improving total phosphorus (TP) removal from municipal wastewater. This EC system was operated in continuous and batch operating mode under differing conditions (e.g. flow rate, initial concentration, electrolysis time, conductivity, voltage) to evaluate correlative phosphorus and electrical energy consumption. The results demonstrated that the EC system could effectively remove phosphorus to meet current stringent discharge standards of less than 0.2mg/L within 2 to 5min. This target was achieved in all ranges of initial TP concentrations studied. It was also found that an increase in conductivity of solution, voltages, or electrolysis time, correlated with improved TP removal efficiency and reduced specific energy consumption. Based on these results, some key economic considerations, such as operating costs, cost-effectiveness, product manufacturing feasibility, facility design and retrofitting, and program implementation are also discussed. This EC process can conclusively be highly efficient in a relatively simple, easily managed, and cost-effective for wastewater treatment system. Copyright © 2016 Elsevier B.V. All rights reserved.

Lithiation-Assisted Strengthening Effect and Reactive Flow in Bulk and Nano-Confined Sulfur Cathodes of Lithium-Sulfur Batteries

NASA Astrophysics Data System (ADS)

Wang, Mingchao; Yu, Jingui; Lin, Shangchao

Sulfur (S) serves as a promising cathode material in Li-ion batteries owing to its abundance on earth, low cost and high theoretical specific capacity 1670 mAhg-1, which is 3-5 times higher than that of current commercial Li-ion batteries. Nowadays, the most popular strategies of using S cathode are based on producing nanostructured carbon matrices (i.e. hollow carbon nanospheres and nanofibers) to sustain S cathode loading. However, the possible stress evolution and mechanical degradation of the confined S cathode in those carbon matrices have never been explored before. In addition, the associated structural and conductivity changes of the confined S cathode during the lithiation/delithiation process plays a significant role in the battery performance. With the above in mind, here we conduct reactive molecular dynamics simulations to investigate the microstructural and stress evolution of the confined S cathode during lithiation/delithiation process. Simulation results indicate an unusual stress relaxation state in LixS compounds at lower Li concentrations (x >0.7). The strength of corresponding Li-S compounds also increases with respect to the Li concentration.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barton, C.; Vowinkel, E.F.; Nawyn, J.P.

The relation of water quality to hydrogeology and land use was evaluated using analysis of water samples from 71 wells in the northern part of the Potomac-Raritan-Magothy aquifer system in New Jersey. The sampling network was evaluated for variations in hydrogeology. Well depths, pumping rates, and the number of wells in the confined and unconfined parts of the aquifer system did not differ among land-use groups. The influences of hydrogeologic factors on water quality were evaluated without considering land use. Shallow wells had the highest specific conductance and major ion concentrations. Water from wells in the unconfined part of themore » aquifer system had the highest dissolved organic carbon concentration. Dissolved oxygen and nitrate concentrations were lowest, trace metals concentrations were highest, and phenols were detected most frequently in groundwater from undeveloped land. Major ions and trace metals concentrations were lowest, dissolved oxygen and copper concentrations were highest, and pesticides were most frequently detected in groundwater from agricultural land. Nitrate concentrations were highest and orthophosphate, nitrite, and purgeable organics were detected most frequently in groundwater from urban land. These water quality data were compared to data from the same aquifer system in southern New Jersey. Frequencies of detection of purgeable organics among land-use groups were similar in the northern and southern areas. 69 refs., 23 figs., 16 tab.« less

Bioenvironmental and radiological-safety feasibility studies, Atlantic-Pacific Interoceanic Canal. Phase 2, Freshwater ecology: Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Templeton, W.L.; Dean, J.M.; Watson, D.G.

1968-06-28

The purpose of this program is to conduct studies in the freshwater environment to acquire data needed to evaluate and predict the potential radiation hazards to human populations in the defined regions of proposed nuclear excavations in the Republics of Panama and Colombia. The results of the field surveys conducted in Phase II are presented in this report. Specifically, the data describes the elemental composition of the major components of the ecosystem, and reports the calculated stable element concentration factors for the major food organisms. This data provides baseline values from which predictions can be made of the potential maximummore » radionuclide intake by populations using this resource.« less

Agricultural use of municipal wastewater treatment plant ...

EPA Pesticide Factsheets

Agricultural use of municipal wastewater treatment plant sewage sludge as a source of per- and polyfluoroalkyl substance (PFAS) contamination in the environment The National Exposure Research Laboratory (NERL) Human Exposure and Atmospheric Sciences Division (HEASD) conducts research in support of EPA mission to protect human health and the environment. HEASD research program supports Goal 1 (Clean Air) and Goal 4 (Healthy People) of EPA strategic plan. More specifically, our division conducts research to characterize the movement of pollutants from the source to contact with humans. Our multidisciplinary research program produces Methods, Measurements, and Models to identify relationships between and characterize processes that link source emissions, environmental concentrations, human exposures, and target-tissue dose. The impact of these tools is improved regulatory programs and policies for EPA.

Solving the forward problem of magnetoacoustic tomography with magnetic induction by means of the finite element method

NASA Astrophysics Data System (ADS)

Li, Xun; Li, Xu; Zhu, Shanan; He, Bin

2009-05-01

Magnetoacoustic tomography with magnetic induction (MAT-MI) is a recently proposed imaging modality to image the electrical impedance of biological tissue. It combines the good contrast of electrical impedance tomography with the high spatial resolution of sonography. In this paper, a three-dimensional MAT-MI forward problem was investigated using the finite element method (FEM). The corresponding FEM formulae describing the forward problem are introduced. In the finite element analysis, magnetic induction in an object with conductivity values close to biological tissues was first carried out. The stimulating magnetic field was simulated as that generated from a three-dimensional coil. The corresponding acoustic source and field were then simulated. Computer simulation studies were conducted using both concentric and eccentric spherical conductivity models with different geometric specifications. In addition, the grid size for finite element analysis was evaluated for the model calibration and evaluation of the corresponding acoustic field.

Dynamic effective properties of heterogeneous geological formations with spherical inclusions under periodic time variations

NASA Astrophysics Data System (ADS)

Rabinovich, A.; Dagan, G.; Miloh, T.

2013-04-01

In unsteady groundwater flow (or similar processes of heat/electrical conduction), the heterogeneous medium structure is characterized by two random properties, the conductivity K and the specific storativity S. The average head field ⟨H ⟩and the associated effective properties Kef, Sef are determined for a layer with a periodic head drop between boundaries, such that H is periodic in time, and a medium made up of a matrix with a dilute concentration of spherical inclusions. In the common quasi-steady approximation, Kef is equal to the classical steady solution while Sef = SA, the arithmetic mean. We derive expressions for the frequency dependent Kef, Sef, which are generally complex, i.e., dynamic. The main result is the delineation of the ranges of the parameters: dimensionless frequency (ω) and contrasts of conductivity (κ) and storativity (s) between the matrix and the inclusions, for which dynamic effects are significant.

Solving the Forward Problem of Magnetoacoustic Tomography with Magnetic Induction by Means of the Finite Element Method

PubMed Central

Li, Xun; Li, Xu; Zhu, Shanan; He, Bin

2010-01-01

Magnetoacoustic Tomography with Magnetic Induction (MAT-MI) is a recently proposed imaging modality to image the electrical impedance of biological tissue. It combines the good contrast of electrical impedance tomography with the high spatial resolution of sonography. In this paper, three-dimensional MAT-MI forward problem was investigated using the finite element method (FEM). The corresponding FEM formulas describing the forward problem are introduced. In the finite element analysis, magnetic induction in an object with conductivity values close to biological tissues was first carried out. The stimulating magnetic field was simulated as that generated from a three-dimensional coil. The corresponding acoustic source and field were then simulated. Computer simulation studies were conducted using both concentric and eccentric spherical conductivity models with different geometric specifications. In addition, the grid size for finite element analysis was evaluated for model calibration and evaluation of the corresponding acoustic field. PMID:19351978

Electrical properties of methane hydrate + sediment mixtures: The σ of CH 4 Hydrate + Sediment

DOE PAGES

Du Frane, Wyatt L.; Stern, Laura A.; Constable, Steven; ...

2015-07-30

Knowledge of the electrical properties of multicomponent systems with gas hydrate, sediments, and pore water is needed to help relate electromagnetic (EM) measurements to specific gas hydrate concentration and distribution patterns in nature. We built a pressure cell capable of measuring in situ electrical properties of multicomponent systems such that the effects of individual components and mixing relations can be assessed. We first established the temperature-dependent electrical conductivity (σ) of pure, single-phase methane hydrate to be ~5 orders of magnitude lower than seawater, a substantial contrast that can help differentiate hydrate deposits from significantly more conductive water-saturated sediments in EMmore » field surveys. We report σ measurements of two-component systems in which methane hydrate is mixed with variable amounts of quartz sand or glass beads. Sand by itself has low σ but is found to increase the overall σ of mixtures with well-connected methane hydrate. Alternatively, the overall σ decreases when sand concentrations are high enough to cause gas hydrate to be poorly connected, indicating that hydrate grains provide the primary conduction path. Our measurements suggest that impurities from sand induce chemical interactions and/or doping effects that result in higher electrical conductivity with lower temperature dependence. Finally, these results can be used in the modeling of massive or two-phase gas-hydrate-bearing systems devoid of conductive pore water. Further experiments that include a free water phase are the necessary next steps toward developing complex models relevant to most natural systems.« less

Electrical properties of methane hydrate + sediment mixtures: The σ of CH 4 Hydrate + Sediment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Du Frane, Wyatt L.; Stern, Laura A.; Constable, Steven

Knowledge of the electrical properties of multicomponent systems with gas hydrate, sediments, and pore water is needed to help relate electromagnetic (EM) measurements to specific gas hydrate concentration and distribution patterns in nature. We built a pressure cell capable of measuring in situ electrical properties of multicomponent systems such that the effects of individual components and mixing relations can be assessed. We first established the temperature-dependent electrical conductivity (σ) of pure, single-phase methane hydrate to be ~5 orders of magnitude lower than seawater, a substantial contrast that can help differentiate hydrate deposits from significantly more conductive water-saturated sediments in EMmore » field surveys. We report σ measurements of two-component systems in which methane hydrate is mixed with variable amounts of quartz sand or glass beads. Sand by itself has low σ but is found to increase the overall σ of mixtures with well-connected methane hydrate. Alternatively, the overall σ decreases when sand concentrations are high enough to cause gas hydrate to be poorly connected, indicating that hydrate grains provide the primary conduction path. Our measurements suggest that impurities from sand induce chemical interactions and/or doping effects that result in higher electrical conductivity with lower temperature dependence. Finally, these results can be used in the modeling of massive or two-phase gas-hydrate-bearing systems devoid of conductive pore water. Further experiments that include a free water phase are the necessary next steps toward developing complex models relevant to most natural systems.« less

High-resolution vertical profiles of groundwater electrical conductivity (EC) and chloride from direct-push EC logs

NASA Astrophysics Data System (ADS)

Bourke, Sarah A.; Hermann, Kristian J.; Hendry, M. Jim

2017-11-01

Elevated groundwater salinity associated with produced water, leaching from landfills or secondary salinity can degrade arable soils and potable water resources. Direct-push electrical conductivity (EC) profiling enables rapid, relatively inexpensive, high-resolution in-situ measurements of subsurface salinity, without requiring core collection or installation of groundwater wells. However, because the direct-push tool measures the bulk EC of both solid and liquid phases (ECa), incorporation of ECa data into regional or historical groundwater data sets requires the prediction of pore water EC (ECw) or chloride (Cl-) concentrations from measured ECa. Statistical linear regression and physically based models for predicting ECw and Cl- from ECa profiles were tested on a brine plume in central Saskatchewan, Canada. A linear relationship between ECa/ECw and porosity was more accurate for predicting ECw and Cl- concentrations than a power-law relationship (Archie's Law). Despite clay contents of up to 96%, the addition of terms to account for electrical conductance in the solid phase did not improve model predictions. In the absence of porosity data, statistical linear regression models adequately predicted ECw and Cl- concentrations from direct-push ECa profiles (ECw = 5.48 ECa + 0.78, R 2 = 0.87; Cl- = 1,978 ECa - 1,398, R 2 = 0.73). These statistical models can be used to predict ECw in the absence of lithologic data and will be particularly useful for initial site assessments. The more accurate linear physically based model can be used to predict ECw and Cl- as porosity data become available and the site-specific ECw-Cl- relationship is determined.

Data on surface-water, streambed-interstitial water, and bed-sediment quality for selected locations in the small arms impact area of central Fort Gordon, Georgia, September 4-6, 2001

USGS Publications Warehouse

Priest, Sheryln; Stamey, Timothy C.; Lawrence, Stephen J.

2002-01-01

In September 2001, the U.S. Geological Survey, in cooperation with the Environmental and Natural Resources Management Office of the U.S. Army Signal Center and Fort Gordon (U.S. Department of the Army), conducted a chemical assessment of surface water, streambed-interstitial water, and bed sediments within the small arms impact area of Fort Gordon Military Installation. The study was conducted in support of the development of an Integrated Natural Resources Management Plan (INRMP) for Fort Gordon, Georgia. An effective INRMP ensures that natural resources conservation measures and U.S. Army activities on the military base are integrated and consistent with Federal requirements to manage military installations on an ecosystem basis. Filtered water samples were collected from five sites along South Prong Creek and three sites along Marcum Branch Creek for chemical analyses of major ions, nutrients, and selected trace elements. On-site measurements of pH, temperature, specific conductance, and dissolved oxygen were made at the eight sites. Filtered water collected showed varying concentrations in both surface- and streambed-interstitial water. Bed-sediment samples collected from South Prong Creek contain elevated levels of arsenic, barium, beryllium, cadmium, chromium, cobalt, copper, iron, lead, manganese, nickel, selenium, vanadium, and total organic carbon relative to previous concentrations (McConnell and others, 2000). Bed-sediment samples collected from Marcum Branch Creek contain elevated levels of beryllium, copper, lead, manganese, mercury, selenium, and total organic carbon relative to previous concentrations (McConnell and others, 2000).

Utility of bromide and heat tracers for aquifer characterization affected by highly transient flow conditions

NASA Astrophysics Data System (ADS)

Ma, Rui; Zheng, Chunmiao; Zachara, John M.; Tonkin, Matthew

2012-08-01

A tracer test using both bromide and heat tracers conducted at the Integrated Field Research Challenge site in Hanford 300 Area (300A), Washington, provided an instrument for evaluating the utility of bromide and heat tracers for aquifer characterization. The bromide tracer data were critical to improving the calibration of the flow model complicated by the highly dynamic nature of the flow field. However, most bromide concentrations were obtained from fully screened observation wells, lacking depth-specific resolution for vertical characterization. On the other hand, depth-specific temperature data were relatively simple and inexpensive to acquire. However, temperature-driven fluid density effects influenced heat plume movement. Moreover, the temperature data contained "noise" caused by heating during fluid injection and sampling events. Using the hydraulic conductivity distribution obtained from the calibration of the bromide transport model, the temperature depth profiles and arrival times of temperature peaks simulated by the heat transport model were in reasonable agreement with observations. This suggested that heat can be used as a cost-effective proxy for solute tracers for calibration of the hydraulic conductivity distribution, especially in the vertical direction. However, a heat tracer test must be carefully designed and executed to minimize fluid density effects and sources of noise in temperature data. A sensitivity analysis also revealed that heat transport was most sensitive to hydraulic conductivity and porosity, less sensitive to thermal distribution factor, and least sensitive to thermal dispersion and heat conduction. This indicated that the hydraulic conductivity remains the primary calibration parameter for heat transport.

Utility of Bromide and Heat Tracers for Aquifer Characterization Affected by Highly Transient Flow Conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma, Rui; Zheng, Chunmiao; Zachara, John M.

A tracer test using both bromide and heat tracers conducted at the Integrated Field Research Challenge site in Hanford 300 Area (300A), Washington, provided an instrument for evaluating the utility of bromide and heat tracers for aquifer characterization. The bromide tracer data were critical to improving the calibration of the flow model complicated by the highly dynamic nature of the flow field. However, most bromide concentrations were obtained from fully screened observation wells, lacking depth-specific resolution for vertical characterization. On the other hand, depth-specific temperature data were relatively simple and inexpensive to acquire. However, temperature-driven fluid density effects influenced heatmore » plume movement. Moreover, the temperature data contained “noise” caused by heating during fluid injection and sampling events. Using the hydraulic conductivity distribution obtained from the calibration of the bromide transport model, the temperature depth profiles and arrival times of temperature peaks simulated by the heat transport model were in reasonable agreement with observations. This suggested that heat can be used as a cost-effective proxy for solute tracers for calibration of the hydraulic conductivity distribution, especially in the vertical direction. However, a heat tracer test must be carefully designed and executed to minimize fluid density effects and sources of noise in temperature data. A sensitivity analysis also revealed that heat transport was most sensitive to hydraulic conductivity and porosity, less sensitive to thermal distribution factor, and least sensitive to thermal dispersion and heat conduction. This indicated that the hydraulic conductivity remains the primary calibration parameter for heat transport.« less

Effect of chromium substitution on the dielectric properties of mixed Ni-Zn ferrite prepared by WOWS sol–gel technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ashtar, M.; Munir, A.; Anis-ur-Rehman, M.

2016-07-15

Graphical abstract: Variation of AC conductivity (σ{sub AC}) as a function of natural log of angular frequency (lnω) for Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2-x}Cr{sub x}O{sub 4} nanoferrites at room temperature. - Highlights: • Cr doped mixed Ni-Zn ferrites were successfully synthesized by a newly developed WOWS sol gel technique. • The specific surface area and specific surface area to volume ratio increased with decrease in particle size. • The resonance peaks appeared in dielectric loss graphs, shifting towards low frequency with the increase in Cr concentration. • The prepared samples have the lowest values of the dielectric constant. • The dielectricmore » constant were observed to be inversely proportional to square root of the AC resistivity. - Abstract: Cr{sup +3} doped Ni-Zn nanoferrite samples with composition Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2-x}Cr{sub x}O{sub 4}(x = 0.1, 0.2, 0.3, 0.4) were synthesized With Out Water and Surfactant (WOWS) sol-gel technique. The structural, morphological and dielectric properties of the samples were investigated. The lattice constant, crystallite size, theoretical density and porosity of each sample were obtained from X-ray diffraction (XRD) data. The specific surface area and specific surface area to volume ratio increased with the decrease in the size of Cr{sup +3} doped Ni-Zn ferrite nanoparticles, as the concentration of Cr{sup +3} increased. The SEM analysis revealed that the particles were of nano size and of spherical shape. The dielectric parameters such as dielectric constant (ε′) and dielectric loss (tanδ) of all the samples as a function of frequency at room temperature were measured. The AC conductivity (σ{sub AC}) was determined from the dielectric parameters, which showed increasing trend with the rise in frequency.« less

Evaluation of Rehabilitation Efficiency of Clogged wells drilled in fractured bedrock and alluvium

NASA Astrophysics Data System (ADS)

Lee, C.; Hamm, S.; Lee, J.; Ok, S.; Han, S.; Choo, C.; Kim, M.

2011-12-01

In Korea, more than one million of groundwater wells have been developed since 1990s. However, the groundwater wells have not been properly managed. Moreover, the importance of well maintenance and well rehabilitation has not been well recognized. In this circumstance, groundwater wells are usually terminated in 20-year operation due to well clogging, groundwater pollution, land use change, etc. which are originated from physical, chemical, biological, and artificial changes of and around the wells. The clogged state of the wells with diminished amount down to 80-85% can be ameliorated by various rehabilitation techniques as increasing discharge amount as well as extending the durability of the wells. In European countries and the USA, rehabilitation techniques of the clogged wells have been developed with understanding the cause and prevention of well bore clogging since 1990s. In recent years, the Korean Ministry of Environment (KME) recognized the importance of well rehabilitation. Under the support of the KME, this study evaluated the efficieny of rehabilitation using air surging, high-pressure water injection, brush & air surging, and explosive charge methods as applying to seven wells installed in fractured granite of Mt. Geumjeong and one well drilled in alluvial deposit of the Jeungsan-Ri area, Gyeongnam Province in the southeastern part of Korea. Hydraulic conductivity was estimated by using slug and pumping tests before and after well rehabilitation in order to assess physical, chemical, and biological changes of the wells. Hydraulic conductivity and pumping capacity of fractured bedrock are closely related to fracture characteristics such as fracture aperture, frequency, length, orientation, dip angle, interconnectivity, plane features, and filling materials. The evolution of clogging and filling of materials on and around the well makes decrease hydraulic conductivity and pumping capacity of the well. In this study, in addition of hydraulic conductivity estimation, optical televiewer (RG HI-OPTV type) and acoustic televiewer (RG HIRAT type) logs were used to quantitatively detect clogging and filling of the wells. Explosive charge method proved about 166% increase of specific capacity after rehabilitation than before. Water quality change occurred as showing the increase of EC, turbidity, and Ca2+, Mg2+, K+, Mn2+, Zn2+, SO42-, Cl-, F-, NO3-, and SiO2 concentrations, and the decrease of temperature, pH, Eh, DO, and Na+, Fe2+, and HCO3- concentrations. On the other hand, brushing method increased about 184% of specific capacity after rehabilitation than before. Water quality change showed the increase of Eh, DO, and Fe2+, HCO3-, F-, and SiO2 concentrations, and the decrease of temperature, turbidity, pH, EC, and Ca2+, Na+, Mg2+, K+, Mn2+, Zn2+, SO42-, Cl-, and NO3- concentrations. Keywords: slug test, optical and acoustic televiewers, hydraulic conductivity, rehabilitation, clogging. Acknowledgement This work was financially supported by the Korea Ministry of Environment as "The GAIA Project".

Enhancement of Electrical Conductivity in Multicomponent Nanocomposites.

NASA Astrophysics Data System (ADS)

Ni, Xiaojuan; Hui, Chao; Su, Ninghai; Liu, Feng

To date, very limited theoretical or numerical analyses have been carried out to understand the electrical percolation properties in multicomponent nanocomposite systems. In this work, a disk-stick percolation model was developed to investigate the electrical percolation behavior of an electrically insulating matrix reinforced with one-dimensional (1D) and two-dimensional (2D) conductors via Monte Carlo simulation. The effective electrical conductivity was evaluated through Kirchhoff's current law by transforming it into an equivalent resistor network. The percolation threshold, equivalent resistance and conductivity were obtained from the distribution of nodal voltages by solving a system of linear equations with Gaussian elimination method. The effects of size, aspect ratio, relative concentration and contact patterns of 1D/2D inclusions on conductivity performance were examined. Our model is able to predict the electrical percolation threshold and evaluate the conductivity for hybrid systems with multiple components. The results suggest that carbon-based nanocomposites can have a high potential for applications where favorable electrical properties and low specific weight are required. We acknowledge the financial support from DOE-BES (No. DE-FG02-04ER46148).

Geochemistry of stream-sediment samples from the Santa Renia Fields and Beaver Peak quadrangles, northern Carlin Trend, Nevada

USGS Publications Warehouse

Theodore, Ted G.; Kotlyar, Boris B.; Berger, Vladimir I.; Moring, Barry C.; Singer, Donald A.; Edstrom, Sven A.

1999-01-01

A broad west-to-east increase of many metal concentrations has been found in stream sediments during a reconnaissance investigation conducted in conjunction with geologic studies in the Santa Renia Fields and Beaver Peak 7–1/2 minute quadrangles near the northern end of the Carlin trend of gold deposits in the Tuscarora Mountains. This regional increase in metal concentrations coincides with a dramatic change in landform wherein high concentrations of metals in stream sediments appear to correlate directly with areas of high elevations and steep slopes in the Beaver Peak quadrangle. Robust erosion combined with high flow rates in streams from these higher elevations are envisaged to have contributed significantly to increased metal concentrations in the stream sediments by an enhanced presence of minerals with high specific gravities and a correspondingly diminished presence of minerals with low specific gravities. Minerals with low specific gravities probably have been preferentially flushed down stream because of high transporting capacities for sediment by streams in the Beaver Peak quadrangle. In addition, the Carlin trend, a generally northwest-alignment of gold deposits in the Santa Renia Fields quadrangle, is well outlined by arsenic concentrations that include a maximum of approximately 54 parts per million. Further, a weakly developed distal-to-proximal metal zonation towards these gold deposits appears to be defined respectively in plots showing distributions of thallium, arsenic, antimony, and zinc. A broad area of high metal concentrations—including sharply elevated abundances of Ag, As, Au, Cd, Co, Cu, Mn, Ni, P, Sb, Sc, Te, V, and especially Zn—near the southeast corner of the Beaver Peak quadrangle primarily could be the result of stratiform mineralized rocks in the Ordovician Vinini Formation or Devonian Slaven Chert, or the result of a subsequent Mesozoic or Tertiary epigenetic overprint.

Pumping Iron and Silica Bodybuilding

NASA Astrophysics Data System (ADS)

Mcnair, H.; Brzezinski, M. A.; Krause, J. W.; Parker, C.; Brown, M.; Coale, T.; Bruland, K. W.

2016-02-01

The availability of dissolved iron influences the stoichiometry of nutrient uptake by diatoms. Under nutrient replete conditions diatoms consume silicic acid and nitrate in a 1:1 ratio, this ratio increases under iron stress. Using the tracers 32Si and PDMPO, the total community and group-specific silica production rates were measured along a gradient of dissolved iron in an upwelling plume off the California coast. At each station, a control (ambient silicic acid) and +20 µM silicic acid treatment were conducted with each tracer to determine whether silicic acid limitation controlled the rate of silica production. Dissolved iron was 1.3 nmol kg-1 nearshore and decreased to 0.15 nmol kg-1 offshore. Silicic acid decreased more rapidly than nitrate, it was nearly 9 µM higher in the nearshore and 7 µM lower than nitrate in the middle of the transect where the iron concentration had decreased. The rate of diatom silica production decreased in tandem with silicic acid concentration, and silica production limitation by low silicic acid was most pronounced when iron concentrations were >0.4 nmol kg-1. The composition of the diatom assemblage shifted from Chaetoceros spp. dominated nearshore to a more sparse pennate-dominated assemblage offshore. Changes in taxa-specific silica production rates will be reported based on examination of PDMPO labeled cells using confocal microscopy.

The Impact of Iodide-Mediated Ozone Deposition and ...

EPA Pesticide Factsheets

The air quality of many large coastal areas in the United States is affected by the confluence of polluted urban and relatively clean marine airmasses, each with distinct atmospheric chemistry. In this context, the role of iodide-mediated ozone (O3) deposition over seawater and marine halogen chemistry accounted for in both the lateral boundary conditions and coastal waters surrounding the continental U.S. is examined using the Community Multiscale Air Quality (CMAQ) model. Several nested simulations are conducted in which these halogen processes are implemented separately in the continental U.S. and hemispheric CMAQ domains, the latter providing lateral boundary conditions for the former. Overall, it is the combination of these processes within both the continental U.S. domain and from lateral boundary conditions that lead to the largest reductions in modeled surface O3 concentrations. Predicted reductions in surface O3 concentrations occur mainly along the coast where CMAQ typically has large overpredictions. These results suggest that a realistic representation of halogen processes in marine regions can improve model prediction of O3 concentrations near the coast. The National Exposure Research Laboratory (NERL) Computational Exposure Division (CED) develops and evaluates data, decision-support tools, and models to be applied to media-specific or receptor-specific problem areas. CED uses modeling-based approaches to characterize exposures, evaluate fate and

Data Validation Package November 2015 Groundwater and Surface Water Sampling at the Old and New Rifle, Colorado, Processing Sites February 2016

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bush, Richard; Lemke, Peter

Water samples were collected from 36 locations at New Rifle and Old Rifle, Colorado, Processing Sites. Duplicate samples were collected from New Rifle locations 0659 and 0855, and Old Rifle location 0304. One equipment blank was collected after decontamination of non-dedicated equipment used to collect one surface water sample. Sampling and analyses were conducted as specified in the Sampling and Analysis Plan for U.S. Department of Energy Office of Legacy Management Sites (LMS/PRO/S04351, continually updated). New Rifle Site Samples were collected at the New Rifle site from 16 monitoring wells and 7 surface locations in compliance with the December 2008more » Groundwater Compliance Action Plan [GCAP] for the New Rifle, Colorado, Processing Site (LMS/RFN/S01920), with one exception: New Rifle location 0635 could not be sampled because it was inaccessible; a fence installed by the Colorado Department of Transportation prevents access to this location. DOE is currently negotiating access with the Colorado Department of Transportation. Analytes measured at the New Rifle site included contaminants of concern (COCs) (arsenic, molybdenum, nitrate + nitrite as nitrogen, selenium, uranium, and vanadium) ammonia as nitrogen, major cations, and major anions. Field measurements of total alkalinity, oxidation- reduction potential, pH, specific conductance, turbidity, and temperature were made at each location, and the water level was measured at each sampled well. A proposed alternate concentration limit (ACL) for vanadium of 50 milligrams per liter (mg/L), specific to the compliance (POC) wells (RFN-0217, -0659, -0664, and -0669) is included in the New Rifle GCAP. Vanadium concentrations in the POC wells were below the proposed ACL as shown in the time-concentration graphs in the Data Presentation section (Attachment 2). Time-concentration graphs from all other locations sampled are also included in Attachment 2. Sampling location RFN-0195 was misidentified for the June/August 2014 and November 2014 sampling events. (Well RFN-0609 was inadvertently sampled instead of RFN-0195 in 2014.) The results for RFN-0195 have been corrected, and are included in associated time-concentration graphs for this location. Recent results for RFN-0195 are consistent with established trends with the possible exception of vanadium. The most recent result for vanadium showed an increase over recent values. Vanadium concentrations at RFN-0195 and other locations will continue to be evaluated in the future to determine the potential for deviations from established trends. The surface water locations were sampled to monitor the impact of groundwater discharge. COC concentrations at Colorado River surface water locations RFN-0324 and RFN-0326, downgradient of the site, remained low and were consistent with historical results, as shown in the time-concentration graphs. COC concentrations did not indicate there are any impacts related to groundwater discharge to the river. In many cases, elevated COC concentrations at the New Rifle site pond locations were observed, as shown in the time-versus concentration graphs. As noted in the GCAP, this indicates impacts from groundwater discharge to the ponds. Old Rifle Site Samples were collected at the Old Rifle site from eight monitoring wells and five surface locations in compliance with the December 2001 Groundwater Compliance Action Plan for the Old Rifle, Colorado, UMTRA Project Site (GJ0-2000-177-TAR). Analytes measured at the Old Rifle site included COCs (selenium, uranium, and vanadium), major cations, and major anions. Field measurements of total alkalinity, oxidation-reduction potential, pH, specific conductance, turbidity, temperature, were made at each location, and the water level was measured at each sampled well. The monitoring strategy described in the GCAP is designed to determine progress of the natural flushing process in meeting compliance standards for site COCs. Standards for selenium and vanadium are the proposed ACLs of0.05 mg/L and 1.0 mg/L, respectively. For uranium the cleanup goal is the UMTRA standard of 0.044 mg/L or background, whichever is higher. As shown in the time concentration graphs, the uranium concentration exceeds the cleanup goal at groundwater monitoring locations RF0-0304, -0305, -0310, -0655, and -0656. The surface water locations were sampled to monitor the impact of groundwater discharge at Colorado River surface water locations adjacent to (RF0-0396) and downgradient of the site (RF0-0741). COC concentrations remain low and consistent with historical concentrations as shown in the time-concentration graphs (Attachment 2), which indicate no impacts from groundwater discharge to the river.« less

Autoantibodies associated with prenatal and childhood exposure to environmental chemicals in Faroese children.

PubMed

Osuna, Christa E; Grandjean, Philippe; Weihe, Pál; El-Fawal, Hassan A N

2014-11-01

Methylmercury, polychlorinated biphenyls (PCBs), and perfluorinated compounds (PFCs) are ubiquitous and persistent environmental chemicals with known or suspected toxic effects on the nervous system and the immune system. Animal studies have shown that tissue damage can elicit production of autoantibodies. However, it is not known if autoantibodies similarly will be generated and detectable in humans following toxicant exposures. Therefore, we conducted a pilot study to investigate if autoantibodies specific for neural and non-neural antigens could be detected in children at age 7 years who have been exposed to environmental chemicals. Both prenatal and age-7 exposures to mercury, PCBs, and PFCs were measured in 38 children in the Faroe Islands who were exposed to widely different levels of these chemicals due to their seafood-based diet. Concentrations of IgM and IgG autoantibodies specific to both neural (neurofilaments, cholineacetyltransferase, astrocyte glial fibrillary acidic protein, and myelin basic protein) and non-neural (actin, desmin, and keratin) antigens were measured and the associations of these autoantibody concentrations with chemical exposures were assessed using linear regression. Age-7 blood-mercury concentrations were positively associated with titers of multiple neural- and non-neural-specific antibodies, mostly of the IgM isotype. Additionally, prenatal blood-mercury and -PCBs were negatively associated with anti-keratin IgG and prenatal PFOS was negatively associated with anti-actin IgG. These exploratory findings demonstrate that autoantibodies can be detected in the peripheral blood following exposure to environmental chemicals. The unexpected association of exposures with antibodies specific for non-neural antigens suggests that these chemicals may have toxicities that have not yet been recognized. © The Author 2014. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Conductivity detection for monitoring mixing reactions in microfluidic devices.

PubMed

Liu, Y; Wipf, D O; Henry, C S

2001-08-01

A conductivity detector was coupled to poly(dimethylsiloxane)-glass capillary electrophoresis microchips to monitor microfluidic flow. Electroosmotic flow was investigated with both conductivity detection (CD) and the current monitoring method. No significant variation was observed between these methods, but CD showed a lower relative standard deviation. Gradient mixing experiments were employed to investigate the relationship between the electrolyte conductivity and the electrolyte concentration. A good linear response of conductivity to concentration was obtained for solutions whose difference in concentrations were less than 27 mM. The new system holds great promise for precision mixing in microfluidic devices using electrically driven flows.

Effect of precursor concentration and film thickness deposited by layer on nanostructured TiO2 thin films

NASA Astrophysics Data System (ADS)

Affendi, I. H. H.; Sarah, M. S. P.; Alrokayan, Salman A. H.; Khan, Haseeb A.; Rusop, M.

2018-05-01

Sol-gel spin coating method is used in the production of nanostructured TiO2 thin film. The surface topology and morphology was observed using the Atomic Force Microscopy (AFM) and Field Emission Scanning Electron Microscopy (FESEM). The electrical properties were investigated by using two probe current-voltage (I-V) measurements to study the electrical resistivity behavior, hence the conductivity of the thin film. The solution concentration will be varied from 14.0 to 0.01wt% with 0.02wt% interval where the last concentration of 0.02 to 0.01wt% have 0.01wt% interval to find which concentrations have the highest conductivity then the optimized concentration's sample were chosen for the thickness parameter based on layer by layer deposition from 1 to 6 layer. Based on the result, the lowest concentration of TiO2, the surface becomes more uniform and the conductivity will increase. As the result, sample of 0.01wt% concentration have conductivity value of 1.77E-10 S/m and will be advanced in thickness parameter. Whereas in thickness parameter, the 3layer deposition were chosen as its conductivity is the highest at 3.9098E9 S/m.

Reconnaissance of surface-water quality in the North Platte Natural Resources District, western Nebraska, 1993

USGS Publications Warehouse

Steele, G.V.; Cannia, J.C.

1997-01-01

In 1993, the U.S. Geological Survey and the North Platte Natural Resources District began a 3-year study to determine the geohydrology and water quality of the North Platte River alluvial aquifer near Oshkosh, Garden County, Nebraska. The objectives of the study were to determine the geohydrologic properties of the North Platte River alluvial aquifer, to establish a well network for long- term monitoring of concentrations of agricultural chemicals including nitrate and herbicides, and to establish baseline concentrations of major ions in the ground water. To meet these objectives, monitor wells were installed at 11 sites near Oshkosh. The geohydrologic properties of the aquifer were estimated from water-level measurements at selected irrigation wells located in the study area and short- term constant-discharge aquifer tests at two monitor wells. Water samples were collected bimonthly and analyzed for specific conductance, pH, water temperature, dissolved oxygen, and nutrients including dissolved nitrate. Samples were collected semiannually for analysis of major ions, and annually for triazine and acetamide herbicides. Evaluation of the aquifer-test data indicates the hydraulic conductivities of the North Platte River alluvial aquifer range between 169 and 184 feet per day and transmissivities ranged from 12,700 to 26,700 feet-squared per day. The average specific yield for the alluvial aquifer, based on the two aquifer tests, was 0.2. Additional hydrologic data for the alluvial aquifer include a horizontal gradient of about 0.002 foot per foot and estimated ground- water flow velocities of about 0.1 to 1.8 feet per day. Evaluation of the water-quality data indicates that nitrate concentrations exceed the U.S. Environmental Protection Agency's (USEPA) Maximum Contamination Level of 10 milligrams per liter for drinking water in areas to the east and west of Oshkosh. In these areas, nitrate concentrations generally are continuing to rise. West of Oshkosh the highest concentrations are now exceeding 50 milligrams per liter. With the exception of one sample, nitrate concentrations exceeding the Maximum Contamination Level were not detected in three wells used to monitor the ground water flowing into and out of the study area, nor in a monitor well located near a municipal well. Results of the study also indicate that an influx of water from Lost Creek Valley, north of the study area, may be mixing with ground water near Oshkosh and diluting concentrations of nitrate.

Effects of urbanization on stream water quality in the city of Atlanta, Georgia, USA

USGS Publications Warehouse

Peters, N.E.

2009-01-01

A long-term stream water quality monitoring network was established in the city of Atlanta, Georgia during 2003 to assess baseline water quality conditions and the effects of urbanization on stream water quality. Routine hydrologically based manual stream sampling, including several concurrent manual point and equal width increment sampling, was conducted ???12 times annually at 21 stations, with drainage areas ranging from 3.7 to 232 km2. Eleven of the stations are real-time (RT) stations having continuous measures of stream stage/ discharge, pH, dissolved oxygen, specific conductance, water temperature and turbidity, and automatic samplers for stormwater collection. Samples were analyzed for field parameters, and a broad suite of water quality and sediment-related constituents. Field parameters and concentrations of major ions, metals, nutrient species and coliform bacteria among stations were evaluated and with respect to watershed characteristics and plausible sources from 2003 through September 2007. Most constituent concentrations are much higher than nearby reference streams. Concentrations are statistically different among stations for several constituents, despite high variability both within and among stations. Routine manual sampling, automatic sampling during stormflows and RT water quality monitoring provided sufficient information about urban stream water quality variability to evaluate causes of water quality differences among streams. Fecal coliform bacteria concentrations of most samples exceeded Georgia's water quality standard for any water-usage class. High chloride concentrations occur at three stations and are hypothesized to be associated with discharges of chlorinated combined sewer overflows, drainage of swimming pool(s) and dissolution and transport during rainstorms of CaCl2, a deicing salt applied to roads during winter storms. One stream was affected by dissolution and transport of ammonium alum [NH4Al(SO4)2] from an alum-manufacturing plant; streamwater has low pH (<5), low alkalinity and high metals concentrations. Several trace metals exceed acute and chronic water quality standards and high concentrations are attributed to washoff from impervious surfaces.

Background hydrologic information in potential lignite mining areas in north-central Mississippi, August 1984

USGS Publications Warehouse

Kalkhoff, S.J.

1985-01-01

The U.S. Geological Survey, in cooperation with the Mississippi Department of Natural Resources, Bureau of Geology, is conducting a hydrologic data collection program in potential lignite-producing areas in Mississippi. During the last two weeks of August 1984, hydrologic data were collected at 15 stream sites that drain potential lignite mining areas in Lafayette, Calhoun, and Yalobusha Counties. Main channel widths ranged from approximately 60 feet at three streams (Coon Creek near Toccopula, Muckaloon Creek near Tula, and Hurricane Creek near Velma) to approximately 120 feet at two streams (Potlockney Creek near Tula, and Savannah Creek near Bruce). Maximum water depths ranged from less than 1.0 foot at most streams to over 5.0 feet at sites on Potlockney Creek near Tula and McGill Creek near Sarepta. Stream discharge ranged from 0.32 cubic feet per second in Persimmon Creek near Bruce to 18.5 cubic feet per second in Puskus Creek near Etta. The specific conductance of stream water ranged from 25 to 160 microsiemens and dissolved solids concentrations ranged from 22 to 91 mg/L (milligrams per liter). Most major ion concentrations were less than 10 mg/L with the exception of calcium (11 mg/L), sodium (12 mg/L) and sulfate (18 mg/L) in the water of Persimmon Creek near Bruce. Dissolved oxygen concentrations were greater than 5.0 mg/L at all but one site. Turbidity values were generally less than 50 units. Nitrate plus nitrite concentrations were equal to or less than 0.10 mg/L in all streams except in Potlockney Creek near Tula where the concentration was 0.11 mg/L. Copper and selenium concentrations in the water at all sampling sites ranged from below the detection limits (1 microgram/g) to 4 micrograms/g (micrograms per gram) and mercury concentrations in bottom material samples ranged from less than 0.01 microgram/g to 0.15 microgram/g. (USGS)

Water-quality assessment of the Cypress Creek watershed, Warrick County, Indiana

USGS Publications Warehouse

Bobo, Linda L.; Peters, Charles A.

1980-01-01

The U.S. Soil Conservation Service needs chemical, biological, microbiological, and hydrological data to prepare an environmental evaluation of the water quality in the Cypress Creek watershed, Warrick County, Ind., before plans can be devised to (1) improve water quality, (2) minimize flooding, (3) reduce sedimentation, and (4) provide adequate outlets for drainage in the watershed. The U.S. Geological Survey obtained these data for the Soil Conservation Service in a water-quality survey of the watershed from March to August 1979. Past and present surface coal mining is the factor having the greatest impact on water quality in the watershed. The upper reaches of Cypress Creek receive acid-mine drainage from a coal-mine waste slurry during periods of intense rainfall. All the remaining tributaries, except Summer Pecka ditch, drain mined or reclaimed lands. The general water type of Cypress Creek and most of its tributaries is calcium and magnesium sulfate. In contrast, the water type at background site 21 on Summer Pecka ditch is calcium sulfate. Specific conductance ranged from 470 to 4,730 micromhos per centimeter at 25 degrees Celsius, and pH ranged from 1.2 to 8.8. Specific conductance, hardness, and concentrations of major ions and dissolved solids were highest in tributaries affected by mining. The pH was lowest in the same tributaries. Concentrations of iron, manganese, and sulfate in water samples and chlordane, DDT, and PCB 's in streambed samples exceeded water-quality limits set by the U.S. Environmental Protection Agency. (USGS)

The trade-off between safety and efficiency in hydraulic architecture in 31 woody species in a karst area.

PubMed

Fan, Da-Yong; Jie, Sheng-Lin; Liu, Chang-Cheng; Zhang, Xiang-Ying; Xu, Xin-Wu; Zhang, Shou-Ren; Xie, Zong-Qiang

2011-08-01

Karst topography is a special landscape shaped by the dissolution of one or more layers of soluble bedrock, usually carbonate rock such as limestone or dolomite. Due to subterranean drainage, overland flow, extraction of water by plants and evapotranspiration, there may be very limited surface water. The hydraulic architecture that plants use to adapt to karst topography is very interesting, but few systematic reports exist. The karst area in southwestern China is unique when compared with other karst areas at similar latitudes, because of its abundant precipitation, with rainfall concentrated in the growing season. In theory, resistance to water-stress-induced cavitation via air seeding should be accompanied by decreased pore hydraulic conductivity and stem hydraulic conductivity. However, evidence for such trade-offs across species is ambiguous. We measured the hydraulic structure and foliar stable carbon isotope ratios of 31 karst woody plants at three locations in Guizhou Province, China, to evaluate the functional coordination between resistance to cavitation and specific conductivity. We also applied phylogenetically independent contrast (PIC) analysis in situations where the inter-species correlations of functional traits may be biased on the potential similarity of closely related species. The average xylem tension measurement, at which 50% of hydraulic conductivity of the plants was lost (Ψ(50)), was only -1.27 MPa. Stem Ψ(50) was positively associated with specific conductance (K(s)) (P < 0.05) and leaf specific conductance (K(l)) (P < 0.05). However, the PIC correlation for both relationships was not statistically significant. δ(13)C was positively related to K(l) in both the traditional cross-species correlation analysis and the corresponding PIC correlations (P < 0.05). The Huber value (sapwood area:leaf area ratio) was negatively correlated with K(s) in both the traditional cross-species correlation and the corresponding PIC correlations (P < 0.01). The characteristics of hydraulic architecture measured in this study showed that karst plants in China are not highly cavitation-resistant species. This study also supports the idea that there may not be an evolutionary trade-off between resistance to cavitation and specific conductivity in woody plants. Whole-plant hydraulic adjustment may decouple the trade-off relationship between safety and efficiency at the branch level.

Occurrence and Trends of Selected Chemical Constituents in Bottom Sediment, Grand Lake O' the Cherokees, Northeast Oklahoma, 1940-2008

USGS Publications Warehouse

Juracek, Kyle E.; Becker, Mark F.

2009-01-01

After over 100 years of continuous activity, lead and zinc mining in the Tri-State Mining District (hereafter referred to as the TSMD) in parts of southeast Kansas, southwest Missouri, and northeast Oklahoma ended in the 1970s. The mining activity resulted in substantial historical and ongoing input of cadmium, lead, and zinc to the environment including Grand Lake O' the Cherokees (hereafter referred to as Grand Lake), a large reservoir in northeast Oklahoma. To help determine the extent and magnitude of contamination in Grand Lake, a one-year study was conducted by the U.S. Geological Survey in cooperation with the U.S. Fish and Wildlife Service. Bottom-sediment coring at five sites was used to investigate the occurrence of cadmium, lead, zinc, and other selected constituents in the bottom sediment of Grand Lake. Cadmium concentrations in the bottom sediment of Grand Lake ranged from 2.3 to 3.6 mg/kg (milligrams per kilogram) with a median of 3.5 mg/kg (5 samples). Compared to an estimated local background concentration of 0.6 mg/kg, the historical mining activity increased cadmium concentrations by about 280 to 500 percent. Lead concentrations ranged from 35 to 102 mg/kg with a median of 59 mg/kg (50 samples). Compared to an estimated local background concentration of 20 mg/kg, the historical mining activity increased lead concentrations by about 75 to 410 percent. The range in zinc concentrations was 380 to 986 mg/kg with a median of 765 mg/kg (50 samples). Compared to an estimated local background concentration of 100 mg/kg, the historical mining activity increased zinc concentrations by about 280 to 890 percent. With the exception of the most upstream coring site, the lead and zinc depositional profiles generally were similar in terms of the range in concentrations measured and the temporal pattern observed. Depositional profiles for lead and zinc indicated mid-core peaks followed by concentrations that decreased since about the 1980s. The depositional profiles reflect the complex interaction of several factors including historical mining and related activities, mine drainage, remediation, landscape stabilization, precipitation and associated runoff, and the erosion and transport of contaminated and clean sediments within the basin. Compared to sediment-quality guidelines, the Grand Lake samples had cadmium concentrations that were substantially less than the general probable-effects concentration (PEC) (4.98 mg/kg) and a TSMD-specific PEC (11.1 mg/kg). The PECs represent the concentration above which toxic biological effects are likely to occur. Likewise, all sediment samples had lead concentrations that were substantially less than the general PEC (128 mg/kg) and a TSMD-specific PEC (150 mg/kg). Zinc concentrations typically exceeded the general PEC (459 mg/kg), but were substantially less than a TSMD-specific PEC (2,083 mg/kg). Throughout the history of Grand Lake, lead and zinc concentrations in the deposited sediment did not approach or exceed the TSMD-specific PECs. As of 2008, legacy effects of mining still included the delivery of contaminated sediment to Grand Lake by the Spring and Neosho Rivers. The Neosho River, with its larger flows and less-contaminated sediment, likely dilutes the load of contaminated sediment delivered to Grand Lake by the Spring River. The information contained in this report provides a baseline of Grand Lake conditions with which to compare future conditions that may represent a response to changes in mining-related activity in the Grand Lake Basin.

Conversion of estrone to estradiol in male fathead minnows ...

EPA Pesticide Factsheets

Estrogens are frequently observed in aquatic environments associated with anthropogenic influence, such as agricultural runoff and wastewater treatment effluent. While 17â-estradiol (E2) is the most potent naturally-occurring estrogen, estrone (E1) is often found at higher environmental concentrations. However, exogenous sources of E1 could potentially be converted to the more potent E2 through the action of endogenous 17â-hydroxysteroid dehydrogenase activity, specifically, the 17â-hydroxysteroid dehydrogenase type 1 isoform (HSD17B1). Observation of increased plasma E2 concentrations without measureable changes in aromatase (cytochrome P45019a) expression in male fish caged in ambient waters containing elevated concentrations of E1, but low or non-detectable concentrations of E2, suggested this may be occurring in the field. If so, exogenous E1 may have a greater impact on reproductive function in aquatic vertebrates than previously assumed. The present study was conducted to evaluate this hypothesis. Male fathead minnows (Pimephales promelas) exposed to aqueous concentrations of 16.7, 50, and 150 ng E1/L in the laboratory exhibit significantly (p<0.05) elevated plasma E2 concentrations relative to control. Plasma testosterone (T) was elevated at a low E1 exposure concentration (1.8 ng E1/L) and depressed at the highest level of exposure (150 ng E1/L). Additionally, vitellogenin (VTG) mRNA expression was significantly elevated at concentrations of 50 and 10

Compound Specific Concentration and Stable Isotope Ratio Measurements of Atmospheric Particulate Organic Matter and Gas Phase Nitrophenols

NASA Astrophysics Data System (ADS)

Busca, R.; Saccon, M.; Moukhtar, S.; Rudolph, J.

2009-05-01

Atmospheric particulate organic matter (POM) adversely affects health and climate. One of the still poorly understood sources of secondary organic matter (SOM) is the formation of secondary POM from the photo- oxidation of atmospheric volatile organic compounds (VOC). Nitrophenols, which are toxic semi-volatile compounds, are formed in the atmosphere by OH-radical initiated photo-oxidation of aromatic hydrocarbons, such as toluene. A method was developed to determine concentrations and stable carbon isotope ratios of particulate methyl nitrophenols in the atmosphere. This method has been used to quantify methyl nitrophenols, specifically 2-methyl-4-nitrophenol and 4-methyl-2-nitrophenol, found in atmospheric PM samples in trace quantities. Using this method, we conducted measurements of methyl nitrophenols in atmospheric PM in rural and suburban areas in Southern Ontario. The results of these measurements showed that the concentration of methyl nitrophenols in atmospheric PM is much lower than expected from the extrapolation of laboratory experiments and measured atmospheric toluene concentrations. In order to better understand the reasons for these findings, an analytical method for the analysis of nitrophenols in the gas phase is currently being developed. Similarly, the measurement technique is modified to allow analysis of other phenolic products of the oxidation of aromatic hydrocarbons in PM as well as in the gas phase. In this poster, sampling techniques for collection and GC-MS analysis of nitrophenols in gas phase and PM will be presented along with preliminary results from summer 2008 and spring 2009 studies.

Plant communication: mediated by individual or blended VOCs?

PubMed

Ueda, Hirokazu; Kikuta, Yukio; Matsuda, Kazuhiko

2012-02-01

Plants emit volatile organic compounds (VOCs) as a means to warn other plants of impending danger. Nearby plants exposed to the induced VOCs prepare their own defense weapons in response. Accumulated data supports this assertion, yet much of the evidence has been obtained in laboratories under artificial conditions where, for example, a single VOC might be applied at a concentration that plants do not actually experience in nature. Experiments conducted outdoors suggest that communication occurs only within a limited distance from the damaged plants. Thus, the question remains as to whether VOCs work as a single component or a specific blend, and at which concentrations VOCs elicit insect and pathogen defenses in undamaged plants. We discuss these issues based on available literature and our recent work, and propose future directions in this field.

Streamflow and water-quality data for three major tributaries to Reelfoot Lake, west Tennessee, October 1987-March 1988

USGS Publications Warehouse

Yurewicz, M.C.; Carey, W.P.; Garrett, J.W.

1988-01-01

Streamflow and water quality data were collected for three major tributaries to Reelfoot Lake, in West Tennessee, for the period October 1987 through March 1988. The data are presented in graphs and tables. Mean daily discharge data were collected at one site each in the drainage basins of North Reelfoot Creek, South Reelfoot Creek, and Running Slough. Daily mean suspended-sediment concentration data were collected at a site in the North Reelfoot Creek basin. Water quality samples were collected during storm events at the same locations that daily mean streamflow data were collected. Water quality samples were analyzed for concentrations of nutrients and triazine herbicides. Water temperature and specific conductance were measured at the time that samples were collected. (USGS)

Effects of Replacement of External Sodium Chloride with Sucrose on Membrane Currents of the Squid Giant Axon

PubMed Central

Adelman, William J.; Taylor, Robert E.

1964-01-01

It was observed that a reduction of the sodium chloride concentration in the external solution bathing a squid giant axon by replacement with sucrose resulted in marked decreases in the peak inward and steady-state outward currents through the axon membrane following a step decrease in membrane potential. These effects are quantitatively acounted for by the increase in series resistance resulting from the decreased conductivity of the sea water and the assumption that the sodium current obeys a relation of the form I = k1C1 - k2C2 where C1, C2 are internal and external ion activities and k1, k2 are independent of concentration. It is concluded that the potassium ion current is independent of the sodium concentration. That the inward current is carried by sodium ions has been confirmed. The electrical potential (or barrier height) profile in the membrane which drives sodium ions appears to be independent of sodium ion concentration or current. A specific effect of the sucrose on hyperpolarizing currents was observed and noted but not investigated in detail. PMID:14232131

Synthesis and concentration of 2-monoacylglycerols rich in polyunsaturated fatty acids.

PubMed

Zhang, Yu; Wang, Xiaosan; Xie, Dan; Zou, Shuo; Jin, Qingzhe; Wang, Xingguo

2018-06-01

Polyunsaturated fatty acids (PUFA) in 2-monoacylglycerols form exhibit various biological activities and have potential applications in food and pharmaceuticals. Preparation of 2-monoacylglycerols was conducted by enzymatic enthanolysis. The effects of lipase type, substrate weight ratio, reaction time and lipase load on the 2-monoacylglycerols content in the crude product were investigated. Lipozyme 435 behaved as 1,3-specific and high-catalytic-activity lipase in this reaction. Under the optimal conditions (ethanol:oil = 3:1 (w/w), 8% Lipozyme 435, 3 h), 27% 2-monoacylglycerols were obtained. After solvent extraction of 2-monoacylglycerols, the abilities of low temperature crystallization and molecular distillation to concentrate 2-PUFA-monoacylglycerols were compared. Low temperature crystallization concentrated 81.13% and 74.29% PUFA by acetonitrile and hexane, respectively, with over 90% in 2-monoacylglycerol forms. Conversely, molecular distillation yielded a PUFA concentration of 72% but decreased the 2-monoacylglycerols content to 69.81%. Thus, the method including enzymatic ethanolysis and low temperature crystallization is suitable for preparation of 2-monoacylglycerols rich in PUFA. Copyright © 2018 Elsevier Ltd. All rights reserved.

Rocky Mountain snowpack physical and chemical data for selected sites, 2010

USGS Publications Warehouse

Ingersoll, George P.; Mast, M. Alisa; Swank, James M.; Campbell, Chelsea D.

2010-01-01

The Rocky Mountain Snowpack program established a network of snowpack-sampling sites in the Rocky Mountain region, from New Mexico to Montana, to monitor the chemical content of snow and to understand the effects of regional atmospheric deposition on freshwater systems. Scientists with the U.S. Geological Survey, in cooperation with the National Park Service; the U.S. Department of Agriculture Forest Service; the Colorado Department of Public Health and Environment; Teton County, Wyoming; and others, annually collected and analyzed snow-pack samples at 48 or more sites in the Rocky Mountain region during 1993-2010. Sixty-three snowpack-sampling sites were each sampled once in 2010, and those data are presented in this report. Data include acid-neutralization capacity, specific conductance, pH, hydrogen ion concentrations, dissolved concentrations of major constituents (calcium, magnesium, sodium, potassium, ammonium, chloride, sulfate, and nitrate), dissolved organic carbon concentrations, snow-water equivalent, snow depth, total mercury concentrations, and ionic charge balance. Quality-assurance data for field and laboratory blanks and field replicates for 2010 also are included.

Effect of precursor concentration on the electrical properties of LiFePO{sub 4} prepared by solvothermal method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rabbani, Ahmad Yasin; Fakhri, Hafizh A.; Arifin, Muhammad

2016-02-08

Lithium iron phosphate (LiFePO{sub 4}) is frequently used for Li-ion battery cathode. LiFePO{sub 4} has the high specific capacity at 170 mAhg{sup −1}, stable voltage at 3.45 V, stable structure, cheap, and low toxicity. The objective of this research is investigating the effect of precursor concentration on the electrical properties of LiFePO{sub 4} prepared by solvothermal method. LiOH, FeSO{sub 4}, H{sub 3}PO{sub 4}, and citric acid were used as the precursors. The LiOH concentration was varied from 0.3 M to 1.8 M. The Fourier Transform Infrared Spectroscopy (FTIR) measurement identified the Fe-O, O-P-O, and P-O bonds which corresponding to LiFePO{sub 4}.more » The result of 4-point probe measurement shows that, among the prepared samples, the sample from the precursor concentration of 1.8 M has the highest electrical conductivity.« less

The fatty acid profile in different wheat cultivars depending on the level of contamination with microscopic fungi.

PubMed

Stuper-Szablewska, Kinga; Buśko, Maciej; Góral, Tomasz; Perkowski, Juliusz

2014-06-15

Analyses were conducted on 30 winter wheat samples growing under controlled conditions and following inoculation with fungi Fusarium culmorum. In inoculated samples the mean concentration of 30 analysed fatty acids was significantly higher in relation to the control and amounted to 1,396 mg/kg vs. 1,046 mg/kg in the control kernels. Recorded concentrations for individual cultivars were significantly correlated with the concentration of fungal biomass. Higher concentration in the control was recorded only for the acid trans C18:2n-6. It was also found that the acid profiles are characteristic of individual cultivars. Statistical analysis showed that trans C18:2n-6, C18:1, C18:3n-3 and C18:3n-6 were the acids with the greatest discriminatory power in distinguishing inoculated samples from the control. Discriminatory analysis separated individual cultivars into quality classes of winter wheat cultivars depending on the presence of a specific fatty acid profile. Copyright © 2014 Elsevier Ltd. All rights reserved.

Rocky Mountain Snowpack Physical and Chemical Data for Selected Sites, 1993-2008

USGS Publications Warehouse

Ingersoll, George P.; Mast, M. Alisa; Campbell, Donald H.; Clow, David W.; Nanus, Leora; Turk, John T.

2009-01-01

The Rocky Mountain Snowpack program established a network of snowpack-sampling sites in the Rocky Mountain region from New Mexico to Montana to monitor the chemical content of snow to help in the understanding of the effects of atmospheric deposition to this region. The U.S. Geological Survey, in cooperation with the National Park Service, the USDA Forest Service, Teton County in Wyoming, Rio Blanco County in Colorado, Pitkin County in Colorado, and others, collected and analyzed snowpack samples annually for 48 or more sites in the Rocky Mountain region during 1993-2008. Forty-eight of the 162 snow-sampling sites have been sampled annually since 1993. Data include acid-neutralization capacity, specific conductance, pH, hydrogen ion concentrations, dissolved concentrations of major constituents (calcium, magnesium, sodium, potassium, ammonium, chloride, sulfate, and nitrate), dissolved organic carbon concentrations, snow/ water equivalent, snow depth, stable sulfur isotope ratios, total mercury concentrations (beginning in 2001), and ionic charge balance. Quality-assurance data for field and laboratory blanks and field replicates for individual years (1993-2008) also are included.

Clinical performance evaluation of total protein measurement by digital refractometry and characterization of non-protein solute interferences.

PubMed

Hunsaker, Joshua J H; Wyness, Sara P; Snow, Taylor M; Genzen, Jonathan R

2016-12-01

Refractometric methods to measure total protein (TP) in serum and plasma specimens have been replaced by automated biuret methods in virtually all routine clinical testing. A subset of laboratories, however, still report using refractometry to measure TP in conjunction with serum protein electrophoresis. The objective of this study was therefore to conduct a modern performance evaluation of a digital refractometer for TP measurement. Performance evaluation of a MISCO Palm Abbe™ digital refractometer was conducted through device familiarization, carryover, precision, accuracy, linearity, analytical sensitivity, analytical specificity, and reference interval verification. Comparison assays included a manual refractometer and an automated biuret assay. Carryover risk was eliminated using a demineralized distilled water (ddH 2 O) wash step. Precision studies demonstrated overall imprecision of 2.2% CV (low TP pool) and 0.5% CV (high TP pool). Accuracy studies demonstrated correlation to both manual refractometry and the biuret method. An overall positive bias (+5.0%) was observed versus the biuret method. On average, outlier specimens had an increased triglyceride concentration. Linearity was verified using mixed dilutions of: a) low and high concentration patient pools, or b) albumin-spiked ddH 2 O and high concentration patient pool. Decreased recovery was observed using ddH 2 O dilutions at low TP concentrations. Significant interference was detected at high concentrations of glucose (>267 mg/dL) and triglycerides (>580 mg/dL). Current laboratory reference intervals for TP were verified. Performance characteristics of this digital refractometer were validated in a clinical laboratory setting. Biuret method remains the preferred assay for TP measurement in routine clinical analyses.

Relation between Enterococcus concentrations and turbidity in fresh and saline recreational waters, coastal Horry County, South Carolina, 2003–04

USGS Publications Warehouse

Landmeyer, James E.; Garigen, Thomas J.

2016-06-24

The positive relation observed between turbidity and Enterococcus concentrations in surface water at the water-quality data collection station located in the channel that drains a freshwater swamp may be attributed to bacterial survival in the abundant channel bed sediments that characterized this more naturalized area. Surface-water bed sediments collected near each water-quality data collection station and the surf zone were incubated in static microcosms in the laboratory and analyzed for Enterococcus concentrations over time. Enterococcus concentrations continued to persist in bed sediments collected in the channel that drains the swamp even after almost 4 months of incubation. Conversely, enterococci were not observed to persist in bed sediments characterized by high specific conductance. Although it is currently (2016) unknown whether this persistence of enterococci demonstrates growth or viability, the data indicate that enterococci can exist in channel bed-sediment environments outside of a host for a long time. This observation confirms previous reports that challenge the use of Enterococcus concentrations as an indicator of the recent introduction of fecal-related material and the associated acute risk to other pathogens.

Understanding determinants of unequal distribution of stillbirth in Tehran, Iran: a concentration index decomposition approach.

PubMed

Almasi-Hashiani, Amir; Sepidarkish, Mahdi; Safiri, Saeid; Khedmati Morasae, Esmaeil; Shadi, Yahya; Omani-Samani, Reza

2017-05-17

The present inquiry set to determine the economic inequality in history of stillbirth and understanding determinants of unequal distribution of stillbirth in Tehran, Iran. A population-based cross-sectional study was conducted on 5170 pregnancies in Tehran, Iran, since 2015. Principal component analysis (PCA) was applied to measure the asset-based economic status. Concentration index was used to measure socioeconomic inequality in stillbirth and then decomposed into its determinants. The concentration index and its 95% CI for stillbirth was -0.121 (-0.235 to -0.002). Decomposition of the concentration index showed that mother's education (50%), mother's occupation (30%), economic status (26%) and father's age (12%) had the highest positive contributions to measured inequality in stillbirth history in Tehran. Mother's age (17%) had the highest negative contribution to inequality. Stillbirth is unequally distributed among Iranian women and is mostly concentrated among low economic status people. Mother-related factors had the highest positive and negative contributions to inequality, highlighting specific interventions for mothers to redress inequality. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Reduction of oxygen concentration by heater design during Czochralski Si growth

NASA Astrophysics Data System (ADS)

Zhou, Bing; Chen, Wenliang; Li, Zhihui; Yue, Ruicun; Liu, Guowei; Huang, Xinming

2018-02-01

Oxygen is one of the highest-concentration impurities in single crystals grown by the Czochralski (CZ) process, and seriously impairs the quality of the Si wafer. In this study, computer simulations were applied to design a new CZ system. A more appropriate thermal field was acquired by optimization of the heater structure. The simulation results showed that, compared with the conventional system, the oxygen concentration in the newly designed CZ system was reduced significantly throughout the entire CZ process because of the lower crucible wall temperature and optimized convection. To verify the simulation results, experiments were conducted on an industrial single-crystal furnace. The experimental results showed that the oxygen concentration was reduced significantly, especially at the top of the CZ-Si ingot. Specifically, the oxygen concentration was 6.19 × 1017 atom/cm3 at the top of the CZ-Si ingot with the newly designed CZ system, compared with 9.22 × 1017 atom/cm3 with the conventional system. Corresponding light-induced degradation of solar cells based on the top of crystals from the newly designed CZ system was 1.62%, a reduction of 0.64% compared with crystals from the conventional system (2.26%).

Specific-conductance, water-temperature, and water-level data, San Francisco Bay, California, for water years 2001-2002

USGS Publications Warehouse

Buchanan, P.A.

2003-01-01

This article presents time-series plots of specific-conductance, water-temperature, and water-level data collected in San Francisco Bay during water years 2001 and 2002 (October 1, 2000, through September 30, 2002). Specific-conductance and water-temperature data were recorded at 15-minute intervals at the following US Geological Survey (USGS) locations (Figure 1): • Suisun Bay at Benicia Bridge, near Benicia, California (BEN) (site # 11455780) • Carquinez Strait at Carquinez Bridge, near Crockett, California (CARQ) (site # 11455820) • Napa River at Mare Island Causeway, near Vallejo, California (NAP) (site # 11458370) • San Pablo Strait at Point San Pablo, California (PSP) (site # 11181360) • San Pablo Bay at Petaluma River Channel Marker 9, California (SPB) (site # 380519122262901) • San Francisco Bay at Presidio Military Reservation, California (PRES) (site # 11162690) • San Francisco Bay at Pier 24, at San Francisco, California (P24) (site # 11162700) • San Francisco Bay at San Mateo Bridge, near Foster City, California (SMB) (site # 11162765). Water-level data were recorded only at PSP through January 1, 2001. Suspended-sediment concentration data also were collected at most of these sites and were published by Buchanan and Ganju (2003). The data from PSP, PRES, P24, and SMB were recorded by the California Department of Water Resources (DWR) before 1988, by the USGS National Research Program from 1988 to 1989, and by the USGSDWR cooperative program since 1990. BEN, CARQ, NAP, and SPB were established in 1998 by the USGS.

Quality of ground water in southeastern and south-central Washington, 1982

USGS Publications Warehouse

Turney, G.L.

1986-01-01

In 1982 groundwater was sampled at over 100 sites in the southeastern-south central region of Washington and analyzed for pH, specific conductance, and concentrations of fecal-coliform bacteria, major dissolved irons, and dissolved iron, manganese, and nitrate. Twenty percent of the samples were analyzed for concentrations of dissolved aluminum, arsenic, barium, cadmium, chromium, cooper, lead, mercury, selenium, silver, and zinc. The predominant water type was calcium bicarbonate. Some sodium bicarbonate water was found in samples from the Lower Yakima, Horse Heaven Hills, and Walla Walla-Tucannon subregions. Dissolved solids concentrations were typically less than 500 mg/L (milligrams per liter). Median iron and manganese concentrations were less than 20 micrograms/L except in the Palouse subregion, where the median concentration of iron was 200 micrograms/L and the median concentrations of manganese was 45 micrograms/L. Generally, trace-metal concentrations were also less than 10 micrograms/L except for barium, copper, and zinc. Nitrate concentrations were less than 1.0 mg/L in waters from half the wells sampled. Concentrations greater than 5.0 mg/L were found in areas of the Lower Yakima, Walla Walla-Tucannon and Hanford subregions. No fecal-coliform bacteria were detected. U.S. Environmental Protection Agency drinking water regulation limits were generally not exceeded, except for occasional high concentrations of nitrate or dissolved solids. The historical data for the region were evaluated for these same constituents. Quantitative differences were found, but the historical and 1982 data led to similar qualitative conclusions. (USGS)

Growth of the extremophilic Deinococcus geothermalis DSM 11302 using co-substrate fed-batch culture.

PubMed

Bornot, Julie; Molina-Jouve, Carole; Uribelarrea, Jean-Louis; Gorret, Nathalie

2014-02-01

Deinococcus geothermalis metabolism has been scarcely studied to date, although new developments on its utilization for bioremediation have been carried out. So, large-scale production of this strain and a better understanding of its physiology are required. A fed-batch experiment was conducted to achieve a high cell density non-limiting culture of D. geothermalis DSM 11302. A co-substrate nutritional strategy using glucose and yeast extract was carried out in a 20-L bioreactor in order to maintain a non-limited growth at a maximal growth rate of 1 h(-1) at 45 °C. Substrate supplies were adjusted by monitoring online culture parameters and physiological data (dissolved oxygen, gas analyses, respiratory quotient, biomass concentration). The results showed that yeast extract could serve as both carbon and nitrogen sources, although glucose and ammonia were consumed too. Yeast extract carbon-specific uptake rate reached a value 4.5 times higher than glucose carbon-specific uptake rate. Cell concentration of 9.6 g L(-1) dry cell weight corresponding to 99 g of biomass was obtained using glucose and yeast extract as carbon and nitrogen sources.

Air pollution and mortality: effect modification by personal characteristics and specific cause of death in a case-only study.

PubMed

Qiu, Hong; Tian, Linwei; Ho, Kin-Fai; Pun, Vivian C; Wang, Xiaorong; Yu, Ignatius T S

2015-04-01

Short-term effects of air pollution on mortality have been well documented in the literature worldwide. Less is known about which subpopulations are more vulnerable to air pollution. We conducted a case-only study in Hong Kong to examine the potential effect modification by personal characteristics and specific causes of death. Individual information of 402,184 deaths of non-external causes and daily mean concentrations of air pollution were collected from 2001 to 2011. For a 10 μg/m(3) increase of pollution concentration, people aged ≥ ∇65 years (compared with younger ages) had a 0.9-1.8% additional increase in mortality related to PM, NO2, and SO2. People dying from cardiorespiratory diseases (compared with other non-external causes) had a 1.6-2.3% additional increase in PM and NO2 related mortality. Other subgroups that were particularly susceptible were females and those economically inactive. Lower socioeconomic status and causes of cardiorespiratory diseases would increase the likelihood of death associated with air pollution. Copyright © 2015 Elsevier Ltd. All rights reserved.

Quantum dot-based microfluidic biosensor for cancer detection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghrera, Aditya Sharma; School of Engineering and Technology, ITM University, Gurgaon-122017; Pandey, Chandra Mouli

2015-05-11

We report results of the studies relating to fabrication of an impedimetric microfluidic–based nucleic acid sensor for quantification of DNA sequences specific to chronic myelogenous leukemia (CML). The sensor chip is prepared by patterning an indium–tin–oxide (ITO) coated glass substrate via wet chemical etching method followed by sealing with polydimethylsiloxane (PDMS) microchannel for fluid control. The fabricated microfluidic chip comprising of a patterned ITO substrate is modified by depositing cadmium selenide quantum dots (QCdSe) via Langmuir–Blodgett technique. Further, the QCdSe surface has been functionalized with specific DNA probe for CML detection. The probe DNA functionalized QCdSe integrated miniaturized system hasmore » been used to monitor target complementary DNA concentration by measuring the interfacial charge transfer resistance via hybridization. The presence of complementary DNA in buffer solution significantly results in decreased electro-conductivity of the interface due to presence of a charge barrier for transport of the redox probe ions. The microfluidic DNA biosensor exhibits improved linearity in the concentration range of 10{sup −15} M to 10{sup −11} M.« less

Pesticide residue quantification analysis by hyperspectral imaging sensors

NASA Astrophysics Data System (ADS)

Liao, Yuan-Hsun; Lo, Wei-Sheng; Guo, Horng-Yuh; Kao, Ching-Hua; Chou, Tau-Meu; Chen, Junne-Jih; Wen, Chia-Hsien; Lin, Chinsu; Chen, Hsian-Min; Ouyang, Yen-Chieh; Wu, Chao-Cheng; Chen, Shih-Yu; Chang, Chein-I.

2015-05-01

Pesticide residue detection in agriculture crops is a challenging issue and is even more difficult to quantify pesticide residue resident in agriculture produces and fruits. This paper conducts a series of base-line experiments which are particularly designed for three specific pesticides commonly used in Taiwan. The materials used for experiments are single leaves of vegetable produces which are being contaminated by various amount of concentration of pesticides. Two sensors are used to collected data. One is Fourier Transform Infrared (FTIR) spectroscopy. The other is a hyperspectral sensor, called Geophysical and Environmental Research (GER) 2600 spectroradiometer which is a batteryoperated field portable spectroradiometer with full real-time data acquisition from 350 nm to 2500 nm. In order to quantify data with different levels of pesticide residue concentration, several measures for spectral discrimination are developed. Mores specifically, new measures for calculating relative power between two sensors are particularly designed to be able to evaluate effectiveness of each of sensors in quantifying the used pesticide residues. The experimental results show that the GER is a better sensor than FTIR in the sense of pesticide residue quantification.

Effective thermal conductivity of isotropic polymer composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tavman, I.H.

1998-07-01

The effective thermal conductivity of tin powder filled high density polyethylene composites is investigated experimentally as a function of filler concentration and the measured values are compared with the existing theoretical and empirical models. Samples are prepared by compression molding process, up to 16% volumetric concentration of tin particles. The thermal conductivity is measured by a modified hot wire technique in a temperature range from about 0 to 70 C. Experimental results show a region of low particle content, up to about 10% volume concentration, where the increase in thermal conductivity is rather slow. The filler particles are dispersed inmore » the matrix material in this region, the thermal conductivity is best predicted by Maxwell`s model and Nielsen`s model with A = 1.5, {phi}{sub m} = 0.637. Whereas, at high filler concentrations, the filler particles tend to form agglomerates and conductive chains in the direction of heat flow resulting in a rapid increase in thermal conductivity. A model developed by Agari and Uno estimates the thermal conductivity in this region, using two experimentally determined constants.« less

Water-Quality Characteristics for Sites in the Tongue, Powder, Cheyenne, and Belle Fourche River Drainage Basins, Wyoming and Montana, Water Years 2001-05, with Temporal Patterns of Selected Long-Term Water-Quality Data

USGS Publications Warehouse

Clark, Melanie L.; Mason, Jon P.

2007-01-01

Water-quality sampling was conducted regularly at stream sites within or near the Powder River structural basin in northeastern Wyoming and southeastern Montana during water years 2001-05 (October 1, 2000, to September 30, 2005) to characterize water quality in an area of coalbed natural gas development. The U.S. Geological Survey, in cooperation with the Wyoming Department of Environmental Quality, characterized the water quality at 22 sampling sites in the Tongue, Powder, Cheyenne, and Belle Fourche River drainage basins. Data for general hydrology, field measurements, major-ion chemistry, and selected trace elements were summarized, and specific conductance and sodium-adsorption ratios were evaluated for relations with streamflow and seasonal variability. Trend analysis for water years 1991-2005 was conducted for selected sites and constituents to assess change through time. Average annual runoff was highly variable among the stream sites. Generally, streams that have headwaters in the Bighorn Mountains had more runoff as a result of higher average annual precipitation than streams that have headwaters in the plains. The Powder River at Moorhead, Mont., had the largest average annual runoff (319,000 acre-feet) of all the sites; however, streams in the Tongue River drainage basin had the highest runoff per unit area of the four major drainage basins. Annual runoff in all major drainage basins was less than average during 2001-05 because of drought conditions. Consequently, water-quality samples collected during the study period may not represent long-term water-quality con-ditions for all sites. Water-quality characteristics were highly variable generally because of streamflow variability, geologic controls, and potential land-use effects. The range of median specific-conductance values among sites was smallest in the Tongue River drainage basin. Median values in that basin ranged from 643 microsiemens per centimeter at 25 degrees Celsius (?S/cm at 25?C) on the Tongue River to 1,460 ?S/cm at 25?C on Prairie Dog Creek. The Tongue River drainage basin has the largest percentage of area underlain by Mesozoic-age and older rocks and by more resistant rocks. In addition, the higher annual precipitation and a steeper gradient in this basin compared to basins in the plains produce relatively fast stream velocities, which result in a short contact time between stream waters and basin materials. The Powder River drainage basin, which has the largest drainage area and most diverse site conditions, had the largest range of median specific-conductance values among the four major drainage basins. Median values in that basin ranged from 680 ?S/cm at 25?C on Clear Creek to 5,950 ?S/cm at 25?C on Salt Creek. Median specific-conductance values among sites in the Cheyenne River drainage basin ranged from 1,850 ?S/cm at 25?C on Black Thunder Creek to 4,680 ?S/cm at 25?C on the Cheyenne River. The entire Cheyenne River drainage basin is in the plains, which have low precipitation, soluble geologic materials, and relatively low gradients that produce slow stream velocities and long contact times. Median specific-conductance values among sites in the Belle Fourche River drainage basin ranged from 1,740 ?S/cm at 25?C on Caballo Creek to 2,800 ?S/cm at 25?C on Donkey Creek. Water in the study area ranged from a magnesium-calcium-bicarbonate type for some sites in the Tongue River drainage basin to a sodium-sulfate type at many sites in the Powder, Cheyenne, and Belle Fourche River drainage basins. Little Goose Creek, Goose Creek, and the Tongue River in the Tongue River drainage basin, and Clear Creek in the Powder River drainage basin, which have headwaters in the Bighorn Mountains, consistently had the smallest median dissolved-sodium concentrations, sodium-adsorption ratios, dissolved-sulfate concentrations, and dissolved-solids concentrations. Salt Creek, Wild Horse Creek, Little Powder River, and the Cheyenne River, which have headwat

Nutrient Enrichment in Estuaries from Discharge of Shallow Ground Water, Mt. Desert Island, Maine

USGS Publications Warehouse

Culbertson, Charles W.; Huntington, Thomas G.; Caldwell, James M.

2007-01-01

Nutrient enrichment from atmospheric deposition, agricultural activities, wildlife, and domestic sources is a concern at Acadia National Park because of the potential problem of water-quality degradation and eutrophication in its estuaries. Water-quality degradation has been observed at the Park?s Bass Harbor Marsh estuary but not in Northeast Creek estuary. Previous studies at Acadia National Park have estimated nutrient inputs to estuaries from atmospheric deposition and surface-water runoff, but the importance of shallow ground water that may contain nutrients derived from domestic or other sources is unknown. Northeast Creek and Bass Harbor Marsh estuaries were studied to (1) identify shallow ground-water seeps, (2) assess the chemistry of the water discharged from selected seeps, and (3) assess the chemistry of ground water in shallow ground-water hyporheic zones. The hyporheic zone is defined here as the region beneath and lateral to a stream bed, where there is mixing of shallow ground water and surface water. This study also provides baseline chemical data for ground water in selected bedrock monitoring wells and domestic wells on Mt. Desert Island. Water samples were analyzed for concentrations of nutrients, wastewater compounds, dissolved organic carbon, pH, dissolved oxygen, temperature and specific conductance. Samples from bedrock monitoring wells also were analyzed for alkalinity, major cations and anions, and trace metals. Shallow ground-water seeps to Northeast Creek and Bass Harbor Marsh estuaries at Acadia National Park were identified and georeferenced using aerial infrared digital imagery. Monitoring included the deployment of continuously recording temperature and specific conductance sensors in the seep discharge zone to access marine or freshwater signatures related to tidal flooding, gradient-driven shallow ground-water flow, or shallow subsurface flow related to precipitation events. Many potential shallow ground-water discharge zones were identified from aerial thermal imagery during flights in May and December 2003 in both estuaries. The occurrence of ground-water seeps was confirmed using continuous and discrete measurements of temperature and specific conductance in selected seeps and in the adjacent estuaries that showed salinity anomalies reflecting the input of freshwater in these complex tidal systems. Analysis of water samples from shallow ground water in the hyporheic zone and from ground-water seeps indicated the presence of elevated concentrations of dissolved nitrogen, compared to concentrations in the adjacent estuaries and surface-water tributaries draining into the estuaries. These findings indicate that shallow ground water is a source of dissolved nitrogen to the estuaries. Orthophosphate levels were low in ground water in the hyporheic zone in Bass Harbor Marsh, but somewhat higher in one hyporheic-zone well in Northeast Creek compared with the concentrations in both estuaries that were at or below detection limits. Household wastewater-related compounds were not detected in ground water in the hyporheic zone. Analysis of water samples from domestic and bedrock monitoring wells developed in fractured bedrock indicated that concentrations of dissolved nitrogen, phosphorus, and household wastewater-related compounds were typically at or below detection, suggesting that the aquifers sampled had not been contaminated from septic sources.

Water quality of the St. Clair River, Lake St. Clair, and their U.S. tributaries, 1946-2005

USGS Publications Warehouse

Healy, Denis F.; Chambers, Douglas B.; Rachol, Cynthia M.; Jodoin, Richard S.

2007-01-01

The St. Clair River/Lake St. Clair waterway forms an international boundary between the United States and Canada. The waters of the area are an important part of the cultural heritage of the area and serves as an important water-supply and power-generating resource; the waterway also supports an economy based largely on recreation, agriculture, and manufacturing. This report was undertaken as part of the Lake St. Clair Regional Monitoring Project for the purpose of providing a comprehensive assessment of the hydrological, chemical, and physical state of the surface water of Lake St. Clair and its tributaries. The data varied in focus and density over the period of compilation which in many cases this variation prevented the completion of statistical analyses because data did not meet minimum comparability or quality requirements for those tests. Comparison of water quality of the Belle, Black, Clinton, and Pine River Basins, as well as basins of minor rivers in the study area, showed that water quality in many of the tributaries, particularly the Clinton River and some of the minor rivers, was degraded compared to the water quality of the St. Clair River/Lake St. Clair waterway. Data analyses included comparison of nutrients, chloride, specific conductance, turbidity, biochemical oxygen demand (BOD), and pesticides among the basins and the St. Clair River. Median concentrations of total nitrate were well below the recommended USEPA total nitrogen ambient water-quality criterion of 0.54 mg/L as N for nutrient ecoregion VII for all study-area streams except the Clinton River. More than 93 percent of the phosphorus concentrations for the Belle, Black, Pine and minor river basins and 84 percent of the phosphorus concentrations for the Clinton River Basin are greater than the USEPA recommended ambient total phosphorus criterion of 0.033 mg/L for rivers and streams. Nine chloride concentrations exceeded the USEPA criterion maximum concentration (CMC) for chloride set at 860 mg/L for all study-area streams, with the six largest being in the Belle River Basin. Higher chloride concentrations were increasingly common from 2002 to 2005. The urban minor river basins had the highest median specific conductance, whereas the agricultural Pine River Basin had the lowest median specific conductance. The median values of BOD for the five basins in the study area ranged from 2.4 mg/L for the Pine River Basin to 3.2 mg/L for the Black and Clinton River Basins, whereas the median for the St. Clair River was 0.5 mg/L. In 1985, the highest concentrations of pesticides were found in samples from the mouth of the Clinton River; however, in 1996–98, the majority of high pesticide concentrations were found in samples from the Black River. Changing land-use patterns, specifically conversion of agricultural lands to urban/residential lands in the Clinton River Basin, may explain this difference. Trend analysis was done for four stream sites where adequate data were available. These analyses identified no significant water-quality changes at a stream site on the Black River, where land-use patterns have changed little in the past few decades. This stands in marked contrast to trend analysis for three stream sites in the Clinton River Basin, which has undergone significant land-use change. The changes at the Clinton River stream sites, ranging from 5 to 13 significant trends, were generally decreases in nutrients and increases in total dissolved solids (TDS) and chloride. The greater flow volume of the St. Clair River/Lake St. Clair waterway is able to assimilate incoming dissolved and suspended constituents from tributaries with little effect upon its overall water quality, although incomplete mixing may result in localized water-quality impairment downstream from tributary confluences. Mixing effects on Lake St. Clair water quality was also demonstrated in analysis of Escherichia coli (E. coli) data collected at paired nearshore/offshore sites, which reflected similarity in water quality among many paired sites.

Ground-water monitoring plan, water quality, and variability of agricultural chemicals in the Missouri River alluvial aquifer near the City of Independence, Missouri, well field, 1998-2000

USGS Publications Warehouse

Kelly, Brian P.

2002-01-01

A detailed ground-water sampling plan was developed and executed for 64 monitoring wells in the city of Independence well field to characterize ground-water quality in the 10-year zone of contribution. Samples were collected from monitoring wells, combined Independence well field pumpage, and the Missouri River at St. Joseph, Missouri, from 1998 through 2000. In 328 ground-water samples from the 64 monitoring wells and combined well field pumpage samples, specific conductance values ranged from 511 to 1,690 microsiemens per centimeter at 25 degrees Celsius, pH values ranged from 6.4 to 7.7, water temperature ranged from 11.3 to 23.6 degrees Celsius, and dissolved oxygen concentrations ranged from 0 to 3.3 milligrams per liter. In 12 samples from the combined well field pumpage samples, specific conductance values ranged from 558 to 856 microsiemens per centimeter at 25 degrees Celsius, pH values ranged from 6.9 to 7.7, water temperature ranged from 5.8 to 22.9 degrees Celsius, and dissolved oxygen concentrations ranged from 0 to 2.4 milligrams per liter. In 45 Missouri River samples, specific conductance values ranged from 531 to 830 microsiemens per centimeter at 25 degrees Celsius, pH ranged from 7.2 to 8.7, water temperature ranged from 0 to 30 degrees Celsius, and dissolved oxygen concentrations ranged from 5.0 to 17.6 milligrams per liter. The secondary maximum contaminant level for sulfate in drinking water was exceeded once in samples from two monitoring wells, the maximum contaminant level (MCL) for antimony was exceeded once in a sample from one monitoring well, and the MCL for barium was exceeded once in a sample from one monitoring well. The MCL for iron was exceeded in samples from all monitoring wells except two. The MCL for manganese was exceeded in all samples from monitoring wells and combined well field pumpage. Enzyme linked immunoassay methods indicate total benzene, toluene, ethyl benzene, and xylene (BTEX) was detected in samples from five wells. The highest total BTEX concentration was less than the MCL of toluene, ethyl benzene, or xylene but greater than the MCL for benzene. Total BTEX was not detected in samples from any well more than once. Atrazine was detected in samples from nine wells, and exceeded the MCL once in a sample from one well. Alachlor was detected in samples from 22 wells but the MCL was never exceeded in any sample. Samples from five wells analyzed for a large number of organic compounds indicate concentrations of volatile organic compounds did not exceed the MCL for drinking water. No semi-volatile organic compounds were detected; dieldrin was detected in one well sample, and no other pesticides, herbicides, polychlorinated biphenyls, or polychlorinated napthalenes were detected. Dissolved ammonia, dissolved nitrite plus nitrate, dissolved orthophosphorus, alachlor, and atrazine analyses were used to determine the spatial and temporal variability of agricultural chemicals in ground water. Detection frequencies for dissolved ammonia increased with well depth, decreased with depth for dissolved nitrite plus nitrate, and remained relatively constant with depth for dissolved orthophosphorus. Maximum concentrations of dissolved ammonia, dissolved nitrite plus nitrate, and dissolved orthophosphorus were largest in the shallowest wells and decreased with depth, which may indicate the land surface as the source. However, median concentrations increased with depth for dissolved ammonia, were less than the detection limit for dissolved nitrite plus nitrate, and decreased with depth for dissolved orthophosphorus. This pattern does not indicate a well-defined single source for these constituents. Dissolved orthophosphorus median concentrations were similar, but decreased slightly with depth, and may indicate the land surface as the source. Seasonal variability of dissolved ammonia, dissolved nitrite plus nitrate, a

Fair performance comparison of different carbon blacks in lithium-sulfur batteries with practical mass loadings - Simple design competes with complex cathode architecture

NASA Astrophysics Data System (ADS)

Jozwiuk, Anna; Sommer, Heino; Janek, Jürgen; Brezesinski, Torsten

2015-11-01

The lithium-sulfur system is one of the most promising next generation battery systems, as elemental sulfur is cheap, abundant and has a high theoretical specific capacity. Although much research is conducted on complex sulfur/carbon composites and architectures, it is difficult to compare the performance of the cathodes to one another. Factors, such as different electrolyte composition and cell components strongly affect the cyclability of the battery. Here, we show the importance of optimizing ;standard; conditions to allow for fair performance comparison of different carbon blacks. Our optimal electrolyte-to-sulfur ratio is 11 μL mgsulfur-1 and high concentrations of LiNO3 (>0.6 M) are needed because nitrate is consumed continuously during cycling. Utilizing these standard conditions, we tested the cycling behavior of four types of cathodes with individual carbon blacks having different specific surface areas, namely Printex-A, Super C65, Printex XE-2 and Ketjenblack EC-600JD. Both the specific capacity and polysulfide adsorption capability clearly correlate with the surface area of the carbon being used. High specific capacities (>1000 mAh gsulfur-1 at C/5) are achieved with high surface area carbons. We also demonstrate that a simple cathode using Ketjenblack EC-600JD as the conductive matrix material can well compete with those having complex architectures or additives.

LH750 hematology analyzers to identify malaria and dengue and distinguish them from other febrile illnesses.

PubMed

Sharma, P; Bhargava, M; Sukhachev, D; Datta, S; Wattal, C

2014-02-01

Tropical febrile illnesses such as malaria and dengue are challenging to differentiate clinically. Automated cellular indices from hematology analyzers may afford a preliminary rapid distinction. Blood count and VCS parameters from 114 malaria patients, 105 dengue patients, and 105 febrile controls without dengue or malaria were analyzed. Statistical discriminant functions were generated, and their diagnostic performances were assessed by ROC curve analysis. Three statistical functions were generated: (i) malaria-vs.-controls factor incorporating platelet count and standard deviations of lymphocyte volume and conductivity that identified malaria with 90.4% sensitivity, 88.6% specificity; (ii) dengue-vs.-controls factor incorporating platelet count, lymphocyte percentage and standard deviation of lymphocyte conductivity that identified dengue with 81.0% sensitivity and 77.1% specificity; and (iii) febrile-controls-vs.-malaria/dengue factor incorporating mean corpuscular hemoglobin concentration, neutrophil percentage, mean lymphocyte and monocyte volumes, and standard deviation of monocyte volume that distinguished malaria and dengue from other febrile illnesses with 85.1% sensitivity and 91.4% specificity. Leukocyte abnormalities quantitated by automated analyzers successfully identified malaria and dengue and distinguished them from other fevers. These economic discriminant functions can be rapidly calculated by analyzer software programs to generate electronic flags to trigger-specific testing. They could potentially transform diagnostic approaches to tropical febrile illnesses in cost-constrained settings. © 2013 John Wiley & Sons Ltd.

Physical signs of dehydration in the elderly.

PubMed

Shimizu, Miyuki; Kinoshita, Kensuke; Hattori, Kazuya; Ota, Yoshio; Kanai, Takao; Kobayashi, Hiroyuki; Tokuda, Yasuharu

2012-01-01

Dehydration is a common condition and frequent cause of hospitalization in older people, despite the caregiver's high attention in attempt to avoid its occurrence. In this study, various physical signs were examined as clinical signs of dehydration in elderly. A prospective observational study was conducted in an acute care teaching hospital. Consecutive elderly patients who were admitted to the Department of Medicine were evaluated. Dehydration was defined as a calculated serum osmolality above 295 mOsm/L. The patients diagnosed as dehydrated or not dehydrated were observed for physical signs of dehydration. Data of blood and urine chemistry analysis were also compared between the two groups. A total of 27 elderly patients admitted with acute medical conditions were included in this study. For the physical signs, dry axilla had moderate sensitivity (44%) and excellent specificity (89%) to detect dehydration. Sunken eyes and delayed capillary refill time also showed relatively good specificity (83%). For laboratory data, the mean concentrations of serum sodium of the dehydrated group (146 mEq/L) was significantly higher (p<0.01) than those of the non-dehydrated group (134 mEq/L). Physical signs of dehydration in elderly showed relatively good specificity but poor sensitivity. The evaluation of the axillary moisture could help assess dehydration as well as laboratory data analysis such as serum sodium concentration.

Conductivity and spectroscopic investigation of bis(trifluoromethanesulfonyl)imide solution in ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide.

PubMed

Yu, Lei; Pizio, Benjamin S; Vaden, Timothy D

2012-06-07

Protic ionic liquids (PILs) are promising alternatives to water for swelling Nafion as a fuel cell proton exchange membrane (PEM). PILs can significantly improve the high-temperature performance of a PEM. The proton dissociation and solvation mechanisms in a PIL, which are keys to understanding the proton transportation and conductivity, have not been fully explored. In this paper, we used FTIR, Raman, and electronic spectroscopy with computational simulation techniques to explore the spectroscopic properties of bis(trifluoromethanesulfonyl)imide (HTFSI) solutions in 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMITFSI) ionic liquid at concentrations from ∼0.1 to as high as ∼1.0 M. Solution conductivities were measured at room temperature and elevated temperatures up to ∼65 °C. The solution structure and properties depend on the concentration of HTFSI. At lower concentration, around 0.1 M, the HTFSI solution has higher conductivity than pure BMITFSI. However, the conductivity decreases when the concentration increases from 0.1 to 1.0 M. Temperature-dependent conductivities followed the Vogel-Fulcher-Tamman equation at all concentrations. Conductivity and spectroscopy results elucidate the complicated ionization and solvation mechanism of HTFSI in BMITFSI solutions. Raman spectroscopy and density functional theory (DFT) calculations are consistent with the complete ionization of HTFSI to generate solvated H(+) at low concentrations. FTIR, Raman, and electronic spectroscopic results as well as DFT computational simulation indicated that when the concentration is as high as 1.0 M, a significant amount of TFSI(-) is protonated, most likely at the imide nitrogen.

Water quality of surficial aquifers in the Georgia-Florida Coastal Plain

USGS Publications Warehouse

Crandall, C.A.; Berndt, M.P.

1996-01-01

The National Water Quality Assessment Program of the U.S. Geological Survey established the Georgia-Florida Coastal Plain study unit in 1991. The ground-water study-unit survey was conducted in 1993 to provide a broad over-view of water quality in surficial aquifers. Three land resource provinces were included in the Georgia-Florida Coastal Plain study-unit survey: the Central Florida Ridge, the Coastal Flatwoods, and the Southern Coastal Plain. The U.S. Geological Survey sampled 37 wells in surficial aquifers, 18 in the Coastal Flatwoods and 19 in the Southern Coastal Plain. The Florida Department of Environmental Protection sampled 27 wells tapping surficial aquifers in the Central Florida Ridge as part of the background ground-water quality monitoring network from 1985 through 1989. The data were used to characterize water quality in surficial aquifers of the Central Florida Ridge. Results of the study-unit survey indicated that dissolved solids concentrations in ground water were mostly less than 100 mg/L (milligrams per liter). Higher medians of pH, specific conductance, and concentrations of calcium, bicarbonate, and dissolved solids were measured in samples from the Central Florida Ridge compared to the Southern Coastal Plain and Coastal Flatwoods, probably because of a greater percentage of carbonate minerals in aquifer materials. The U.S. Environmental Protection Agency secondary maximum contaminant level for iron of 300 ug/L (micrograms per liter) in drinking water was exceeded in 15 of 45 samples. Concentrations of nitrate as nitrogen were less than 3.0 mg/L in most samples (74 percent), indicating little or no influence from human activity. Only five samples (9 percent) had concentrations above 10 mg/L, the U.S. Environmental Protection Agency maximum contaminant level for nitrate concentration in drinking water. Significantly lower median concentrations of nitrate were measured in samples from polyvinyl chloride monitoring wells with diameters less than 6 inches than in large diameter, uncased, or iron-cased wells. The median nitrate concentration was 0.05 mg/L in water from monitoring wells, 1.0 mg/L in samples from iron cased wells, and 2.0 mg/L in samples from uncased wells. Concentrations of volatile organic compounds were mostly less than the detection levels and exceeded 1 ug/L in only four samples. Compounds detected at concentrations greater than 1 ug/L were: tetrachloroethane (8.77 ug/L), toluene (23 ug/L) and chloromethane (21 ug/L). Atrazine, desethyl-atrazine, and metolachlor were the only pesticides detected; concentrations were less than 0.02 ug/L, except for metolachlor (2.5 ug/L). Detection of organic compounds in surficial aquifer may be associated with specific activities or sources near the well. Concentrations of radon exceeded the U.S. Environmental Protection Agency proposed maximum contaminant level of 300 picocuries per liter (pCi/L) in 33 samples from wells on the Coastal Flatwoods and the Southern Coastal Plain. Concentrations as high as 13,000 pCi/L were detected in northern Florida. Although uranium concentrations were less than 1 ug/L in all but one sample (1.3 ug/L) from the Southern Coastal Plain, elevated radon concentrations indicate that uranium is present in aquifer material. Uranium is most likely sorbed to iron oxides and clays in subsurface materials. Tritium concentrations indicated that ground water was recharged by precipitation during the past 40 years. Higher concentrations of tritium in ground water were found in the northern part of the study area and may be related to Savannah River Nuclear Facility.

Relation of water quality to land use in the drainage basins of four tributaries to the Toms River, New Jersey, 1994--1995

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hunchak-Kariouk, K.

1999-01-01

This report describes the results of a study to determine the relation between land use and the water quality of four tributaries to the Toms River--Long Swamp Creek, Wrangel Brook, Davenport Branch, and Jakes Branch. The constituent concentrations and yield values presented in this report are based on water-quality and streamflow data collected at seven sites during base flow and stormflow conditions during May 1994 to October 1995. Concentrations and yields (area-normalized instantaneous load values) during periods of base flow and stormflow in the growing and nongrowing seasons are presented for sites on Long Swamp Creek, Wrangel Brook, and Davenportmore » Branch. Only concentrations during base flow are presented for the site on Jakes Branch. Water-quality constituents for which concentrations and yield values are reported include total nitrogen, ammonia, nitrate, organic nitrogen, hydrolyzable phosphorus plus orthophosphorus, orthophosphorus, total suspended solids, and fecal-coliform bacteria. Concentrations of nitrite and Escherichia coliform bacteria also are listed. Distributions of constituent concentrations and yields during base flow and stormflow in the growing and nongrowing season are shown in boxplots. Specific conductance, pH, temperature, and dissolved oxygen in the four tributaries also are discussed, and their values are listed.« less

Parallel conductance estimation by hypertonic dilution method with conductance catheter: effects of the bolus concentration and temperature.

PubMed

Herrera, M C; Olivera, J M; Valentinuzzi, M E

1999-07-01

The conductance catheter has gained momentum since its introduction in cardiovascular dynamics back in 1980. However, measuring errors are still blurring its clinical acceptance. The main objective here was to study the effects of the injected saline concentration and temperature on the evaluation of the parallel conductance, Gp, and thus, on the correction volume Vp. That conductance, Gp, and its associated volume, Vp, were computed using 167 saline dilution curves obtained with boluses at different concentrations and temperatures, injected in seven anesthetized closed-chest dogs. The excursion of the total conductance relative to the steady-state value during a saline maneuver showed good correlation with the injected concentration at both studied temperatures. The reference parallel volume (one reference per dog) was defined as the average value obtained with three successive maneuvers, at 6-M concentration and at body temperature; therefore, the method acted as its own reference. The variation of Vp relative to the reference value was clearly dependent on the injected concentration and on its temperature; dispersion was greater at 22 degrees C than at 40 degrees C. The variability would recognize also other causes, such as uncertainty of the extrapolation procedure and the thoracic redistribution of electrical field lines. As conclusion, it is recommended to characterize each maneuver by its concentration and temperature. Body temperature and 6-M concentration appear as the most recommendable combination for the injectate in most animals. Finally, these results intend to characterize the Vp estimation procedure in order to minimize errors. The variability of Vp, in different experimental conditions, demonstrated that both concentration and temperature are additional parameters that may modify the Gp estimate.

Occurrence of Cr(VI) in drinking water of Greece and relation to the geological background.

PubMed

Kaprara, E; Kazakis, N; Simeonidis, K; Coles, S; Zouboulis, A I; Samaras, P; Mitrakas, M

2015-01-08

This study provides a survey on potential Cr(VI) exposure attributed to drinking water in Greece. For this reason, a wide sampling and chemical analysis of tap waters from around 600 sites, supplied by groundwater resources, was conducted focusing on areas in which the geological substrate is predominated by ultramafic minerals. Results indicate that although violations of the current chromium regulation limit in tap water are very rare, 25% of cases showed Cr(VI) concentrations above 10 μg/L, whereas Cr(VI) was detectable in 70% of the samples (>2 μg/L). Mineralogy and conditions of groundwater reservoirs were correlated to suggest a possible Cr(VI) leaching mechanism. Higher Cr(VI) values are observed in aquifers in alluvial and neogene sediments of serpentine and amphibolite, originating from the erosion of ophiolithic and metamorphic rocks. In contrast, Cr(VI) concentration in samples from ophiolithic and metamorphic rocks was always below 10 μg/L due to both low contact time and surface area, as verified by low conductivity and salt concentration values. These findings indicate that under specific conditions, pollution of water by Cr(VI) is favorable by a slow MnO2-catalyzed oxidation of soluble Cr(III) to Cr(VI) in which manganese products [Mn(III)/Mn(II)] are probably re-oxidized by oxygen. Copyright © 2014 Elsevier B.V. All rights reserved.

Overcoming bioanalytical challenges in an Onglyza(®) intravenous [(14)C]microdose absolute bioavailability study with accelerator MS.

PubMed

Xu, Xiaohui Sophia; Dueker, Stephen R; Christopher, Lisa J; Lohstroh, Pete N; Keung, Chi Fung Anther; Cao, Kai Kevin; Bonacorsi, Samuel J; Cojocaru, Laura; Shen, Jim X; Humphreys, W Griffith; Stouffer, Bruce; Arnold, Mark E

2012-08-01

An absolute bioavailability study that utilized an intravenous [(14)C]microdose was conducted for saxagliptin (Onglyza(®)), a marketed drug product for the treatment of Type 2 diabetes mellitus. Concentrations of [(14)C]saxagliptin were determined by accelerator MS (AMS) after protein precipitation, chromatographic separation by UPLC and analyte fraction collection. A series of investigative experiments were conducted to maximize the release of the drug from high-affinity receptors and nonspecific adsorption, and to determine a suitable quantitation range. A technique-appropriate validation demonstrated the accuracy, precision, specificity, stability and recovery of the AMS methodology across the concentration range of 0.025 to 15.0 dpm/ml (disintegration per minute per milliliter), the equivalent of 1.91-1144 pg/ml. Based on the study sample analysis, the mean absolute bioavailability of saxagliptin was 50% in the eight subjects with a CV of 6.6%. Incurred sample reanalysis data fell well within acceptable limits. This study demonstrated that the optimized sample pretreatment and chromatographic separation procedures were critical for the successful implementation of an UPLC plus AMS method for [(14)C]saxagliptin. The use of multiple-point standards are useful, particularly during method development and validation, to evaluate and correct for concentration-dependent recovery, if observed, and to monitor and control process loss and operational variations.

Species-Specific Morphological and Physiological Responses of Four Korean Native Trees Species under Elevated CO2 Concentration using Open Top Chamber

NASA Astrophysics Data System (ADS)

Song, W.; Byeon, S.; Lee, H.; Lee, M.; Lim, H.; Kim, H. S.

2017-12-01

For the last three years, studies on the morphological and physiological characteristics were carried out for four tree species (Pinus densiflora, Quercus acutissima, Sorbus alnifolia and Fraxinus rhynchophylla) which are representative native species of Korea. We used a control site and three open top chambers (con, chamber 1, 2, and 3) which were exposed to ambient and two elevated CO2 concentration ([CO2]); the concentration were the ambient (400ppm) for control and chamber 1 and 1.4 times (560ppm) and 1.8 times (720 ppm) of the atmosphere for chamber 2 and 3, respectively. Leaf mass per area (LMA), stomatal size, density and area were examined to investigate the morphological changes of the trees. Among four species, F. rhynchophylla increased their LMA with increase of CO2 concentration. In addition, F. rhynchophylla showed the decrease of stomatal density significantly (p-value=0.02), while there was no difference in stoma size. These findings resulted in 25.5% and 38.7% decrease of stomata area per unit leaf area calculated by multiplying the size and density of the stomata. On the other hand, all 4 tree species were significantly increased in height and diameter growth with the elevated CO2. However, in the case of Q. acutissima, the increase in height growth was prominent. For physiological characteristics, the maximum photosynthetic rate was faster in the chambers exposed to high [CO2] than that in the control. However the rate of carboxylation and the electron transfer rate showed no particular tendency. The measurement of hydraulic conductivity (Ks, kg/m/s/Mpa) for Crataegus pinnatifida, increased as the [CO2] in the atmosphere increased, and the 50% Loss Conductance (Mpa) tended to increase slightly with the [CO2]. The correlation analysis between hydraulic conductivity and vulnerability to cavitation showed a strong negative correlation (P <0.05), which was unlike the general tendency.

Ionic relaxation in PEO/PVDF-HFP-LiClO4 blend polymer electrolytes: dependence on salt concentration

NASA Astrophysics Data System (ADS)

Das, S.; Ghosh, A.

2016-06-01

In this paper, we have studied the effect of LiClO4 salt concentration on the ionic conduction and relaxation in poly ethylene oxide (PEO) and poly (vinylidene fluoride hexafluoropropylene) (PVDF-HFP) blend polymer electrolytes, in which the molar ratio of ethylene oxide segments to lithium ions (R  =  EO: Li) has been varied between 3 and 35. We have observed two phases in the samples containing low salt concentrations (R  >  9) and single phase in the samples containing high salt concentrations (R  ⩽  9). The scanning electron microscopic images indicate that there exists no phase separation in the blend polymer electrolytes. The temperature dependence of the ionic conductivity shows two slopes corresponding to high and low temperatures and follows Arrhenius relation for the samples containing low salt concentrations (R  >  9). The conductivity relaxation as well as the structural relaxation has been clearly observed at around 104 Hz and 106 Hz for these concentrations of the blended electrolytes. However, a single conductivity relaxation peak has been observed for the compositions with R  ⩽  9. The scaling of the conductivity spectra shows that the relaxation mechanism is independent of temperature, but depends on salt concentration.

Changes in Lipidome Composition during Brain Development in Humans, Chimpanzees, and Macaque Monkeys

PubMed Central

Li, Qian; Bozek, Katarzyna; Xu, Chuan; Guo, Yanan; Sun, Jing; Pääbo, Svante; Sherwood, Chet C.; Hof, Patrick R.; Ely, John J.; Li, Yan; Willmitzer, Lothar

2017-01-01

Lipids are essential components of the brain. Here, we conducted a comprehensive mass spectrometry-based analysis of lipidome composition in the prefrontal cortex of 40 humans, 40 chimpanzees, and 40 rhesus monkeys over postnatal development and adulthood. Of the 11,772 quantified lipid peaks, 7,589 change significantly along the lifespan. More than 60% of these changes occur prior to adulthood, with less than a quarter associated with myelination progression. Evolutionarily, 36% of the age-dependent lipids exhibit concentration profiles distinct to one of the three species; 488 (18%) of them were unique to humans. In both humans and chimpanzees, the greatest extent of species-specific differences occurs in early development. Human-specific lipidome differences, however, persist over most of the lifespan and reach their peak from 20 to 35 years of age, when compared with chimpanzee-specific ones. PMID:28158622

Growth, biomass, and fecundity of Bothriocephalus acheilognathi in a North Carolina cooling reservoir

DOE Office of Scientific and Technical Information (OSTI.GOV)

Riggs, M.R.; Lemly, A.D.; Esch, G.W.

1987-10-01

An investigation of differences in growth, maturation, biomass, and fecundity of Bothriocephalus acheilognathi in 3 host species was conducted on metapopulations from 3 distinct communities in Belews Lake, North Carolina. The results indicated that host-specific differences in growth and biomass were additive among metapopulations from different localities. However, species-specific differences in maturation and fecundity exhibited differential variation between the sites. These site X host interactions were related to host-specific differences in bioaccumulation of selenium at sites that were exposed to effluent from a coal-fired power plant. Significant (alpha = 0.001) statistical associations were observed between selenium concentration in tapeworm tissuemore » and fecundity measures. The results of this study demonstrate that host suitability is determined by morphological, physiological, and behavioral differences in the host species which affect transmission dynamics and the quality and stability of the enteric environment.« less

Conductivity noise in transmembrane ion channels due to ion concentration fluctuations via diffusion.

PubMed

Mak, D O; Webb, W W

1997-03-01

A Green's function approach is developed from first principles to evaluate the power spectral density of conductance fluctuations caused by ion concentration fluctuations via diffusion in an electrolyte system. This is applied to simple geometric models of transmembrane ion channels to obtain an estimate of the magnitude of ion concentration fluctuation noise in the channel current. Pure polypeptide alamethicin forms stable ion channels with multiple conductance states in artificial phospholipid bilayers isolated onto tips of micropipettes with gigaohm seals. In the single-channel current recorded by voltage-clamp techniques, excess noise was found after the background instrumental noise and the intrinsic Johnson and shot noises were removed. The noise que to ion concentration fluctuations via diffusion was isolated by the dependence of the excess current noise on buffer ion concentration. The magnitude of the concentration fluctuation noise derived from experimental data lies within limits estimated using our simple geometric channel models. Variation of the noise magnitude for alamethicin channels in various conductance states agrees with theoretical prediction.

Precipitation, atmospheric deposition, streamflow, and water-quality data from selected sites in the city of Charlotte and Mecklenburg County, North Carolina, 1997–98

USGS Publications Warehouse

Sarver, Kathleen M.; Hazell, W.F.; Robinson, J.B.

1999-01-01

Precipitation data were collected at 46 precipitation sites and 3 atmospheric deposition sites, and hydrologic data were collected at 6 stream sites in the vicinity of Charlotte and Mecklenburg County, North Carolina, from July 1997 through September 1998. Data were collected to identify the type, concentration, and amount of nonpoint-source stormwater runoff in the study area. The data collected include measurements of precipitation; streamflow; physical characteristics, such as water temperature, pH, specific conductance, biochemical oxygen demand, oil and grease, and suspended-sediment concentrations; and concentrations of nutrients, metals and minor constituents, and organic compounds. These data will provide information needed for (1) planned watershed simulation models, (2) estimates of nonpoint-source constituent loadings to the Catawba River, and (3) characterization of water quality in relation to basin conditions. Streamflow and rainfall data have been used to provide early warnings of possible flooding.

Selected chemical analyses of water from formations of Mesozoic and Paleozoic age in parts of Oklahoma, northern Texas, and Union County, New Mexico

USGS Publications Warehouse

Parkhurst, R.S.; Christenson, S.C.

1987-01-01

Hydrochemical data were compiled into a data base as part of the Central Midwest Regional Aquifer System Analysis project. The data consist of chemical analyses of water samples collected from wells that are completed in formations of Mesozoic and Paleozoic age. The data base includes data from the National Water Data Storage and Retrieval System, the Petroleum Data System, the National Uranium Resource Evaluation, and selected publications. Chemical analyses were selected for inclusion within the hydrochemical data base if the total concentration of the cations differed from the total 10 percent or less of the total concentration of all ions. Those analyses which lacked the necessary data for an ionic balance were included if the ratios of dissolved-solids concentration to specific conductance were between 0.55 and 0.75. The tabulated chemical analyses, grouped by county, and a statistical summary of the analyses, listed by geologic unit, are presented.

Influence of chemical disorder on energy dissipation and defect evolution in concentrated solid solution alloys

DOE PAGES

Zhang, Yanwen; Stocks, George Malcolm; Jin, Ke; ...

2015-10-28

A long-standing objective in materials research is to understand how energy is dissipated in both the electronic and atomic subsystems in irradiated materials, and how related non-equilibrium processes may affect defect dynamics and microstructure evolution. Here we show that alloy complexity in concentrated solid solution alloys having both an increasing number of principal elements and altered concentrations of specific elements can lead to substantial reduction in the electron mean free path and thermal conductivity, which has a significant impact on energy dissipation and consequentially on defect evolution during ion irradiation. Enhanced radiation resistance with increasing complexity from pure nickel tomore » binary and to more complex quaternary solid solutions is observed under ion irradiation up to an average damage level of 1 displacement per atom. Understanding how materials properties can be tailored by alloy complexity and their influence on defect dynamics may pave the way for new principles for the design of radiation tolerant structural alloys.« less

A reconnaissance of the effects of a forest fire on water quality in Kings Canyon National Park, California

USGS Publications Warehouse

Hoffman, Ray J.; Ferreira, Rodger F.

1976-01-01

Following two forest fires in the Roaring River drainage basin, Kings Canyon National Park, Calif., water samples were collected from May to July 1974 to determine water-quality changes resulting from the fires. Field measurements included alkalinity , pH, specific conductance, temperature, and discharge. Samples were analyzed in the laboratory for major dissolved chemical constituents, selected plant nutrients, trace metals, suspended sediment, total organic carbon, and seston. Periphytic algae and benthic invertebrate samples were collected. A noticeable increase in the concentration of nitrogen was found in Roaring River immediately downstream from the Moraine Creek fire. The increase in the concentration of inorganic nitrogen compounds, however, was not great enough to pose a serious threat to the aquatic ecosystem. High total organic nitrogen concentrations may have been due, in part, to factors other than the effect of fire. The results of other water-quality measurements were typical of dilute Sierra Nevada streams and indicate that Roaring River was not adversely affected by the fires. (Woodard-USGS)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Becker, C.D.; Woodfield, W.G.; Strand, J.A.

The Freshwater Sciences Section of PNL has initiated biologically oriented studies at the P and M solvent refined coal (SRC) pilot plant on the Fort Lewis Reservation in western Washington. Essentially, the study objectives are to identify residual components in the treated SRC process and assess potential for adverse impact on water quality and aquatic biota. Since inception of research in mid-1976, six static toxicity tests with treated SRC process effluent have been conducted. Toxic components, not yet specifically identified, sometimes occur in the effluent. It is believed these components involve organic hydrocarbons of the phenol and cresol groups. Analysesmore » have been obtained on inorganic and organic constituents in partially-treated and treated process effluent. Concentrations of inorganics identified in the effluent did not differ greatly from their concentrations in Lake Sequalitchew or SRC plant tap water, but the low concentrations may be due primarily to dilution with freshwater before discharge. Organics identified in the effluent are similar to those found in samples contaminated with petroleum, and involve many complex hydrocarbons.« less

Petroleum pollution in mangrove forests sediments from Qeshm Island and Khamir Port-Persian Gulf, Iran.

PubMed

Ebrahimi-Sirizi, Zohreh; Riyahi-Bakhtiyari, Alireza

2013-05-01

The concentrations of total polycyclic aromatic hydrocarbons (PAHs) and 22 individual PAH compounds in 42 surface sediments collected from the mangrove forest of Qeshm Island and Khamir Port (Persian Gulf) were analyzed. PAHs concentrations ranged from 259 to 5,376 ng g(-1) dry weight with mean and median values of 1,585 and 1,146 ng g(-1), respectively. The mangrove sediments had higher percentages of lower molecular weight PAHs and the PAH profiles were dominated by naphthalene. Ratio values of specific PAH compounds were calculated to evaluate the possible source of PAH contamination. This ratios suggesting that the mangrove sediments have a petrogenic input of PAHs. Sediment quality guidelines were conducted to assess the toxicity of PAH compounds. The levels of total PAHs at all of stations except one station, namely Q6, were below the effects range low. Also, concentrations of naphthalene in some stations exceeded the effects range median.

Accumulation patterns of lipophilic organic contaminants in surface sediments and in economic important mussel and fish species from Jakarta Bay, Indonesia.

PubMed

Dwiyitno; Dsikowitzky, Larissa; Nordhaus, Inga; Andarwulan, Nuri; Irianto, Hari Eko; Lioe, Hanifah Nuryani; Ariyani, Farida; Kleinertz, Sonja; Schwarzbauer, Jan

2016-09-30

Non-target screening analyses were conducted in order to identify a wide range of organic contaminants in sediment and animal tissue samples from Jakarta Bay. High concentrations of di-iso-propylnaphthalenes (DIPNs), linear alkylbenzenes (LABs) and polycyclic aromatic hydrocarbons (PAHs) were detected in all samples, whereas phenylmethoxynaphthalene (PMN), DDT and DDT metabolites (DDX) were detected at lower concentrations. In order to evaluate the uptake and accumulation by economic important mussel (Perna viridis) and fish species, contaminant patterns of DIPNs, LABs and PAHs in different compartments were compared. Different patterns of these contaminant groups were found in sediment and animal tissue samples, suggesting compound-specific accumulation and metabolism processes. Significantly higher concentrations of these three contaminant groups in mussel tissue as compared to fish tissue from Jakarta Bay were found. Because P. viridis is an important aquaculture species in Asia, this result is relevant for food safety. Copyright © 2016 Elsevier Ltd. All rights reserved.

Properties of Nanocomposite Nickel-Carbon Films Deposited by Magnetron Sputtering

NASA Astrophysics Data System (ADS)

Grenadyorov, A. S.; Oskomov, K. V.; Solov'ev, A. A.; Rabotkin, S. V.; Zakharov, A. N.; Semenov, V. A.; Oskirko, V. O.; Yelgin, Yu. I.; Korneva, O. S.

2017-12-01

The method of magnetron sputtering was used to produce a-C and a-C:Ni films on substrates of monocrystalline silicon and thermoelectric material of n-type ((Bi2Te3)0.94(Bi2Se3)0.06) and p-type ((Bi2Te3)0.20(Sb2Te3)0.80) conductivity. The authors studied the effect of Ni concentration on specific electric resistance, hardness and adhesion of the produced films. It was demonstrated that specific resistance of a-C films deposited by graphite target sputtering when supplying high bias voltage onto the substrate can be reduced by increasing the share of graphitized carbon. Adding Ni to such films allows additionally reducing their specific resistance. The increase in Ni content is accompanied with the decrease in hardness and adhesion of a-C:Ni films. The acquired values of specific electric resistance and adhesion of a-C:Ni films to thermoelectric materials allow using them as barrier anti-diffusion coatings of thermoelectric modules.

Electrokinetics of the silica and aqueous electrolyte solution interface: Viscoelectric effects.

PubMed

Hsu, Wei-Lun; Daiguji, Hirofumi; Dunstan, David E; Davidson, Malcolm R; Harvie, Dalton J E

2016-08-01

The manipulation of biomolecules, fluid and ionic current in a new breed of integrated nanofluidic devices requires a quantitative understanding of electrokinetics at the silica/water interface. The conventional capacitor-based electrokinetic Electric Double Layer (EDL) models for this interface have some known shortcomings, as evidenced by a lack of consistency within the literature for the (i) equilibrium constants of surface silanol groups, (ii) Stern layer capacitance, (iii) zeta (ζ) potential measured by various electrokinetic methods, and (iv) surface conductivity. In this study, we consider how the experimentally observable viscoelectric effect - that is, the increase of the local viscosity due to the polarisation of polar solvents - affects electrokinetcs at the silica/water interface. Specifically we consider how a model that considers viscoelectric effects (the VE model) performs against two conventional electrokinetic models, namely the Gouy-Chapman (GC) and Basic Stern capacitance (BS) models, in predicting four fundamental electrokinetic phenomena: electrophoresis, electroosmosis, streaming current and streaming potential. It is found that at moderate to high salt concentrations (>5×10(-3)M) predictions from the VE model are in quantitative agreement with experimental electrokinetic measurements when the sole additional adjustable parameter, the viscoelectric coefficient, is set equal to a value given by a previous independent measurement. In contrast neither the GS nor BS models is able to reproduce all experimental data over the same concentration range using a single, robust set of parameters. Significantly, we also show that the streaming current and potential in the moderate to high surface charge range are insensitive to surface charge behaviour (including capacitances) when viscoelectric effects are considered, in difference to models that do not consider these effects. This strongly questions the validity of using pressure based electrokinetic experiments to measure surface charge characteristics within this experimentally relevant high pH and moderate to high salt concentration range. At low salt concentrations (<5×10(-3)M) we find that there is a lack of consistency in previously measured channel conductivities conducted under similar solution conditions (pH, salt concentration), preventing a conclusive assessment of any model suitability in this regime. Copyright © 2016 Elsevier B.V. All rights reserved.

Major ions, nutrients, and trace elements in the Mississippi River near Thebes, Illinois, July through September 1993

USGS Publications Warehouse

Taylor, Howard E.; Antweiler, Ronald C.; Brinton, Terry I.; Roth, David A.; Moody, John A.

1994-01-01

Extensive flooding in the upper Mississippi River Basin during summer 1993 had a significant effect on the water quality of the Mississippi River. To evaluate the change in temporal distribution and transport of dissolved constituents in the Mississippi River, six water samples were collected by a discharge-weighted method from July through September 1993 near Thebes, Illinois. Sampling at this location provided water-quality information from the upper Mississippi, the Missouri, and the Illinois River Basins. Dissolved major constituents that were analyzed in each of the samples included bicarbonate, calcium (Ca), carbonate (C03), chloride (Cl), dissolved organic carbon, magnesium (Mg), potassium (K), silica NOD, sodium (Na), and sulfate (S04). Dissolved nutrients included ammonium ion (NH4), nitrate (N03), nitrite (N02), and orthophosphate (P04) . Dissolved trace elements included aluminum (Al), arsenic (As), barium (Ba), boron (B), beryllium (Be), bromide (Br), cadmium (Cd), chromium (Cr), cobalt, (Co), copper (Cu), fluoride (F), iron (Fe), lead, lithium (Li), manganese (Mn), mercury (Hg), molybdenum (Mo), nickel (Ni), strontium (Sr), thallium, uranium (U), vanadium (V), and zinc (Zn). Other physical properties of water that were measured included specific conductance, pH and suspended-sediment concentration (particle size, less than 63 micrometers). Results of this study indicated that large quantities of dissolved constituents were transported through the river system. Generally, pH, alkalinity, and specific conductance and the concentrations of B, Br, Ca, Cl, Cr, K, Li, Mg, Mo, Na, S04, Sr, U, and V increased as water discharge decreased, while concentrations of F, Hg, and suspended sediment sharply decreased as water discharge decreased after the crest of the flood. Concentrations of other constituents, such as Al, As, Ba, Be, Co, Cu, Ni, N03, N02, NH4, P04, and Si02, varied with time as discharge decreased after the crest of the flood. For most constituents, the load transported during floods generally is much greater than that transported during low-flow conditions. How ever, for Cd, Cr, Fe, Mn, V, and Zn, loads increased substantially as water discharge decreased after the crest of the flood.

The effect of nanoparticles aggregation on the thermal conductivity of nanofluids at very low concentrations: Experimental and theoretical evaluations

NASA Astrophysics Data System (ADS)

Motevasel, Mohsen; Nazar, Ali Reza Solaimany; Jamialahmadi, Mohammad

2018-01-01

Nanoparticles suspended in a base fluid yield increased thermal conductivity, which in turn increases convection heat transfer rate. Prediction of suitable relations for determination of thermal conductivity results in heightened accuracy in the calculation of convection heat transfer coefficient and reduced costs. In the majority of studies performed on the prediction of thermal conductivity, some relations and models were used in which the effect of aggregation of particles, especially at low concentrations was ignored. In this research, the thermal conductivity of the nanofluid is measured experimentally at low volumetric concentrations, within the range of 0.02-0.2% for the nanoparticles of Al2O3, MgO, CuO, and SiC in the base fluid of distilled water. The results obtained from the models are compared by the available models considering and neglecting the effect of aggregation of particles. Within the range of the applied concentrations, the relative absolute average deviation ratio of the thermal conductivity models without considering the aggregation effect in relation with the models considering the aggregate, is observed to be between 2 and 6 times. Therefore, it is recommended that even at low concentrations, the effect of aggregation should be considered in the prediction of thermal conductivity.

Low-temperature thermoelectric, galvanomagnetic, and thermodynamic properties of the type-I clathrate Ba8AuxSi46-x

NASA Astrophysics Data System (ADS)

Aydemir, U.; Candolfi, C.; Ormeci, A.; Oztan, Y.; Baitinger, M.; Oeschler, N.; Steglich, F.; Grin, Yu.

2011-11-01

Polycrystalline samples of the clathrate Ba8AuxSi46-x were synthesized for 0.2 ⩽ x ⩽ 10. The homogeneity range of the type-I clathrate phase was determined to be 3.63 ⩽ x ⩽ 6.10 after annealing at 900 °C, while a lower Au concentration (x ≈ 2.2) was obtained by steel-quenching. Quasisingle phase materials were obtained for 4.10 ⩽ x ⩽ 6.10. In this composition range, thermoelectric properties, including electrical resistivity, thermopower, and thermal conductivity, were investigated between 2 and 350 K. These experiments were complemented by low-temperature specific heat and Hall-effect measurements (2-300 K). First-principles calculations were carried out to determine the evolution of the electronic structure as a function of x. Both theoretical and experimental results evidence a progressive evolution, with the Au content, from a metallic-like behavior towards a highly doped semiconducting state which develops around x = 5.43. At this concentration, a crossover from n- to p-type conduction occurs, suggesting that the present system satisfies the Zintl-Klemm concept, which predicts a transition at x = 5.33. This crossover is traced by Hall-effect data indicating a dominant electronlike response for x ⩽ 5.43, which turns into a holelike signal at higher x values. Analysis of the data based on a single-parabolic-band model under the assumption of a single scattering mechanism of the charge carriers proved to adequately describe the transport properties in the compositional range investigated. Interestingly, the temperature dependence of the lattice thermal conductivity is strongly influenced by the Au concentration: the typical behavior of crystalline insulators in the n-type compounds evolves into a glasslike dependence in the p-type samples. The series Ba8AuxSi46-x thus provides an excellent testing ground for the interplay between crystal structure, electronic properties, and lattice thermal conductivity in type-I clathrates.

Perioperative supplemental oxygen therapy and surgical site infection: a meta-analysis of randomized controlled trials.

PubMed

Qadan, Motaz; Akça, Ozan; Mahid, Suhal S; Hornung, Carlton A; Polk, Hiram C

2009-04-01

To conduct a meta-analysis of randomized controlled trials in which high inspired oxygen concentrations were compared with standard concentrations to assess the effect on the development of surgical site infections (SSIs). A systematic literature search was conducted using the MEDLINE, EMBASE, and Cochrane databases and included a manual search of references of original articles, poster presentations, and abstracts from major meetings ("gray" literature). Twenty-one of 2167 articles met the inclusion criteria. Of these, 5 randomized controlled trials (3001 patients) assessed the effect of perioperative supplemental oxygen use on the SSI rate. Studies used a treatment-inspired oxygen concentration of 80%. Maximum follow-up was 30 days. Data were abstracted by 3 independent reviewers using a standardized data collection form. Relative risks were reported using a fixed-effects model. Results were subjected to publication bias testing and sensitivity analyses. Infection rates were 12.0% in the control group and 9.0% in the hyperoxic group, with relative risk reduction of 25.3% (95% confidence interval [CI], 8.1%-40.1%) and absolute risk reduction of 3.0% (1.1%-5.3%). The overall risk ratio was 0.742 (95% CI, 0.599-0.919; P = .006). The benefit from increasing oxygen concentration was greater in colorectal-specific procedures, with a risk ratio of 0.556 (95% CI, 0.383-0.808; P = .002). Perioperative supplemental oxygen therapy exerts a significant beneficial effect in the prevention of SSIs. We recommend its use along with maintenance of normothermia, meticulous glycemic control, and preservation of intravascular volume perioperatively in the prevention of SSIs.

Negative space charge effects in photon-enhanced thermionic emission solar converters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Segev, G.; Weisman, D.; Rosenwaks, Y.

2015-07-06

In thermionic energy converters, electrons in the gap between electrodes form a negative space charge and inhibit the emission of additional electrons, causing a significant reduction in conversion efficiency. However, in Photon Enhanced Thermionic Emission (PETE) solar energy converters, electrons that are reflected by the electric field in the gap return to the cathode with energy above the conduction band minimum. These electrons first occupy the conduction band from which they can be reemitted. This form of electron recycling makes PETE converters less susceptible to negative space charge loss. While the negative space charge effect was studied extensively in thermionicmore » converters, modeling its effect in PETE converters does not account for important issues such as this form of electron recycling, nor the cathode thermal energy balance. Here, we investigate the space charge effect in PETE solar converters accounting for electron recycling, with full coupling of the cathode and gap models, and addressing conservation of both electric and thermal energy. The analysis shows that the negative space charge loss is lower than previously reported, allowing somewhat larger gaps compared to previous predictions. For a converter with a specific gap, there is an optimal solar flux concentration. The optimal solar flux concentration, the cathode temperature, and the efficiency all increase with smaller gaps. For example, for a gap of 3 μm the maximum efficiency is 38% and the optimal flux concentration is 628, while for a gap of 5 μm the maximum efficiency is 31% and optimal flux concentration is 163.« less

Pesticides exposure assessment of kettleman city using the industrial source complex short-term model version 3.

PubMed

Tao, Jing; Barry, Terrell; Segawa, Randy; Neal, Rosemary; Tuli, Atac

2013-01-01

Kettleman City, California, reported a higher than expected number of birth defect cases between 2007 and 2010, raising the concern of community and government agencies. A pesticide exposure evaluation was conducted as part of a complete assessment of community chemical exposure. Nineteen pesticides that potentially cause birth defects were investigated. The Industrial Source Complex Short-Term Model Version 3 (ISCST3) was used to estimate off-site air concentrations associated with pesticide applications within 8 km of the community from late 2006 to 2009. The health screening levels were designed to indicate potential health effects and used for preliminary health evaluations of estimated air concentrations. A tiered approach was conducted. The first tier modeled simple, hypothetical worst-case situations for each of 19 pesticides. The second tier modeled specific applications of the pesticides with estimated concentrations exceeding health screening levels in the first tier. The pesticide use report database of the California Department of Pesticide Regulation provided application information. Weather input data were summarized from the measurements of a local weather station in the California Irrigation Management Information System. The ISCST3 modeling results showed that during the target period, only two application days of one pesticide (methyl isothiocyanate) produced air concentration estimates above the health screening level for developmental effects at the boundary of Kettleman City. These results suggest that the likelihood of birth defects caused by pesticide exposure was low. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Hydrologic conditions, recharge, and baseline water quality of the surficial aquifer system at Jekyll Island, Georgia, 2012-13

USGS Publications Warehouse

Gordon, Debbie W.; Torak, Lynn J.

2016-03-08

Groundwater levels and specific-conductance measurements showed the dependence of freshwater resources on rainfall to recharge the water-table zone of the surficial aquifer system and to influence groundwater flow on Jekyll Island. The unseasonably dry conditions during November 2012 to April 2013 induced saline water infiltration to the water-table zone from the marshland separating the Jekyll River from the island. A strong correlation (R2 = 0.97) of specific conductance to chloride concentration in water samples from wells installed in the water-table zone provided support for the determination of seasonal directions of groundwater flow by confirming salinity changes in the water-table zone. Unseasonably wet conditions during the late spring to August caused groundwater-flow reversals in some areas. The high dependence of the water-table zone in the surficial aquifer system on precipitation to replenish the aquifer with freshwater underscored the importance of monitoring groundwater levels, water quality, and water use to identify aquifer-discharge conditions that have the potential to promote seawater encroachment and degrade freshwater resources on Jekyll Island.

Temporal Chemical Variations during the Eruption Cycle at Crystal Geyser in Green River, Utah: Inverse Modeling of Fluid Sourcing and Implications to the Geyser Mechanism

NASA Astrophysics Data System (ADS)

Watson, Z. T.; Han, W. S.; Kampman, N.; Grundl, T.; Han, K.

2014-12-01

The most well-known example of a CO2-driven geyser is Crystal geyser in Green River, Utah. In situ monitoring of pressure and temperature and analysis of the elemental and isotopic composition of the emanating fluids has provided useful proxies for determining the geysering cycle, the source of water/CO2 and furthermore the physical constraints at depth which ultimately control the surficial expressions. Crystal geyser is the first geyser in the world which has been shown to go through repeated systematic chemical variations during its eruption cycle. The eruption cycle at Crystal geyser is comprised of 4 parts which follow the order of: minor eruption period (mEP), major eruption period (MEP), aftershock eruptions (Ae) and recharge period (R). Minor eruption periods are characterized by increasing specific conductivity (19.3 to 21.2 mS/cm), Na and Cl concentrations during the first half which plateau until the MEP. The beginning of the MEP denotes a sharp drop in temperature (17.4 to 16.8 ºC) Na, Cl, specific conductivity (21.2 to 18 mS/cm), and increasing concentrations of Fe, Sr, Ca, Mg and Mn. Downhole fluid sampling of the Entrada Sandstone and Navajo Sandstone provided 1 and 4 samples from the aquifers, respectively. The Entrada Sandstone in comparison to the deeper Navajo Sandstone has elevated concentrations of Sr and Fe and has lower concentrations of Na and Cl. Inverse modeling using the chemical characteristics of the Entrada Sandstone, Navajo Sandstone and brine was executed to determine the fractional inputs which comprise Crystal geyser's fluid. Variances in the fractional contribution are dependent on the depth of the sample chosen to be representative of the Navajo Sandstone because the concentration of Na and Cl, among other elements, changes over depth. During the mEP the Navajo Sandstone, Entrada Sandstone and brine supply 50-55%, 44-48% and 1-3% of the total fluid, respectively. During the MEP the Navajo Sandstone, Entrada Sandstone and brine supply 39-43%, 56-59% and 1-2%, respectively. The results imply that the type of geysering seen at the surface is a function of the physical hydrologic characteristics of the supplying formations.

Reconnaissance of surface-water and ground-water quality at the Lincoln Boyhood National Memorial near Lincoln City, Indiana, 2001-02

USGS Publications Warehouse

Buszka, Paul M.; Fowler, Kathleen K.

2005-01-01

In cooperation with the National Park Service, the U.S. Geological Survey investigated water quality of key water bodies at the Lincoln Boyhood National Memorial near Lincoln City in southwestern Indiana. The key water bodies were a stock pond, representing possible nonpoint agricultural effects on water quality; an ephemeral stream, representing the water quality of drainage from forested areas of the park; parking-lot runoff, representing water quality related to roads and parking lots; an unnamed ditch below the parking lot, representing the water quality of drainage from the parking lot and from an adjacent railroad track; and Lincoln Spring, a historical ground-water source representing ground-water conditions near a former diesel-fuel-spill site along a rail line. Water samples were analyzed for pH, temperature, specific conductance, and dissolved oxygen and for concentrations of selected major ions and trace metals, nutrients, organic constituents, and Escherichia coli bacteria. Surface-water-quality data of water samples from the park represent baseline conditions for the area in relation to the data available from previous studies of area streams. Specific-conductance values and concentrations of most major ions and various nutrients in surface-water samples from the park were smaller than those reported for samples collected in other USGS studies in areas adjacent to the park. Water-quality-management issues identified by this investigation include potentially impaired water quality from parking-lot runoff, unknown effects on surface-water quality from adjacent railroads, and the potential impairment of water quality in Lincoln Spring from human influences. Parking-lot runoff is a source of calcium, alkalinity, iron, lead, and organic carbon in the water samples from the unnamed ditch. Detection of small concentrations of petroleum hydrocarbons in water from Lincoln Spring could indicate residual contamination from a 1995 diesel-fuel spill and cleanup. The concentration of nitrite plus nitrate in water from Lincoln Spring was 16.5 milligrams per liter as nitrogen, greater than the State of Indiana standard for nitrate in drinking water (10 milligrams per liter as nitrogen). Lead concentrations in samples from the stock pond, parking-lot runoff, and the unnamed ditch exceeded the Indiana chronic aquatic criteria.

Mass production of C50 carotenoids by Haloferax mediterranei in using extruded rice bran and starch under optimal conductivity of brined medium.

PubMed

Chen, C Will; Hsu, Shu-hui; Lin, Ming-Tse; Hsu, Yi-hui

2015-12-01

Microbial carotenoids have potentially healthcare or medical applications. Haloferax mediterranei was difficult to economically grow into a large quantities as well as producing a valuable pigment of carotenoids. This study reports a novel investigation into the optimal conductivity on the mass production of carotenoids from H. mediterranei. The major component at about 52.4% in the extracted red pigment has been confirmed as bacterioruberin, a C50 carotenoids, by liquid chromatography separation and mass spectrometry analysis. By maintaining higher conductivity of 40 S/m in the brined medium, the cell concentration attained to 7.73 × 10(9) cells/L with low pigments concentration of 125 mg/L. When the conductivity was controlled at about 30 S/m, we obtained the highest cell concentration to 1.29 × 10(10) cells/L with pigments of 361.4 mg/L. When the conductivity was maintained at optimal 25 S/m, the pigments can be increased to maximum value of 555.6 mg/L at lower cell concentration of 9.22 × 10(9) cells/L. But conductivity below 20 S/m will cause the significant decrease in cell concentration as well as pigments due to the osmotic stress around the cells. Red pigment of carotenoids from an extremely halophilic archaebacterium could be efficiently produced to a high concentration by applying optimal conductivity control in the brined medium with extruded low-cost rice bran and corn starch.

Fluctuation-enhanced electric conductivity in electrolyte solutions.

PubMed

Péraud, Jean-Philippe; Nonaka, Andrew J; Bell, John B; Donev, Aleksandar; Garcia, Alejandro L

2017-10-10

We analyze the effects of an externally applied electric field on thermal fluctuations for a binary electrolyte fluid. We show that the fluctuating Poisson-Nernst-Planck (PNP) equations for charged multispecies diffusion coupled with the fluctuating fluid momentum equation result in enhanced charge transport via a mechanism distinct from the well-known enhancement of mass transport that accompanies giant fluctuations. Although the mass and charge transport occurs by advection by thermal velocity fluctuations, it can macroscopically be represented as electrodiffusion with renormalized electric conductivity and a nonzero cation-anion diffusion coefficient. Specifically, we predict a nonzero cation-anion Maxwell-Stefan coefficient proportional to the square root of the salt concentration, a prediction that agrees quantitatively with experimental measurements. The renormalized or effective macroscopic equations are different from the starting PNP equations, which contain no cross-diffusion terms, even for rather dilute binary electrolytes. At the same time, for infinitely dilute solutions the renormalized electric conductivity and renormalized diffusion coefficients are consistent and the classical PNP equations with renormalized coefficients are recovered, demonstrating the self-consistency of the fluctuating hydrodynamics equations. Our calculations show that the fluctuating hydrodynamics approach recovers the electrophoretic and relaxation corrections obtained by Debye-Huckel-Onsager theory, while elucidating the physical origins of these corrections and generalizing straightforwardly to more complex multispecies electrolytes. Finally, we show that strong applied electric fields result in anisotropically enhanced "giant" velocity fluctuations and reduced fluctuations of salt concentration.

Fluctuation-enhanced electric conductivity in electrolyte solutions

PubMed Central

Péraud, Jean-Philippe; Nonaka, Andrew J.; Bell, John B.; Donev, Aleksandar; Garcia, Alejandro L.

2017-01-01

We analyze the effects of an externally applied electric field on thermal fluctuations for a binary electrolyte fluid. We show that the fluctuating Poisson–Nernst–Planck (PNP) equations for charged multispecies diffusion coupled with the fluctuating fluid momentum equation result in enhanced charge transport via a mechanism distinct from the well-known enhancement of mass transport that accompanies giant fluctuations. Although the mass and charge transport occurs by advection by thermal velocity fluctuations, it can macroscopically be represented as electrodiffusion with renormalized electric conductivity and a nonzero cation–anion diffusion coefficient. Specifically, we predict a nonzero cation–anion Maxwell–Stefan coefficient proportional to the square root of the salt concentration, a prediction that agrees quantitatively with experimental measurements. The renormalized or effective macroscopic equations are different from the starting PNP equations, which contain no cross-diffusion terms, even for rather dilute binary electrolytes. At the same time, for infinitely dilute solutions the renormalized electric conductivity and renormalized diffusion coefficients are consistent and the classical PNP equations with renormalized coefficients are recovered, demonstrating the self-consistency of the fluctuating hydrodynamics equations. Our calculations show that the fluctuating hydrodynamics approach recovers the electrophoretic and relaxation corrections obtained by Debye–Huckel–Onsager theory, while elucidating the physical origins of these corrections and generalizing straightforwardly to more complex multispecies electrolytes. Finally, we show that strong applied electric fields result in anisotropically enhanced “giant” velocity fluctuations and reduced fluctuations of salt concentration. PMID:28973890

Trade-offs between water transport capacity and drought resistance in neotropical canopy liana and tree species.

PubMed

De Guzman, Mark E; Santiago, Louis S; Schnitzer, Stefan A; Álvarez-Cansino, Leonor

2017-10-01

In tropical forest canopies, it is critical for upper shoots to efficiently provide water to leaves for physiological function while safely preventing loss of hydraulic conductivity due to cavitation during periods of soil water deficit or high evaporative demand. We compared hydraulic physiology of upper canopy trees and lianas in a seasonally dry tropical forest to test whether trade-offs between safety and efficiency of water transport shape differences in hydraulic function between these two major tropical woody growth forms. We found that lianas showed greater maximum stem-specific hydraulic conductivity than trees, but lost hydraulic conductivity at less negative water potentials than trees, resulting in a negative correlation and trade-off between safety and efficiency of water transport. Lianas also exhibited greater diurnal changes in leaf water potential than trees. The magnitude of diurnal water potential change was negatively correlated with sapwood capacitance, indicating that lianas are highly reliant on conducting capability to maintain leaf water status, whereas trees relied more on stored water in stems to maintain leaf water status. Leaf nitrogen concentration was related to maximum leaf-specific hydraulic conductivity only for lianas suggesting that greater water transport capacity is more tied to leaf processes in lianas compared to trees. Our results are consistent with a trade-off between safety and efficiency of water transport and may have implications for increasing liana abundance in neotropical forests. © The Author 2016. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Experimental study on thermal conductivity of solution combustion synthesized MgO nanoparticles dispersed in water and ethylene glycol (50:50) binary mixture

NASA Astrophysics Data System (ADS)

Suseel Jai Krishnan, S.; P. K., Nagarajan

2017-05-01

In this present investigation, experiments were conducted on the magnesia nanoparticles (8-18 nm) synthesized by the solution combustion method, which was dispersed in the binary mixture of water-ethylene glycol (50:50) to prepare stable MgO-water-ethylene glycol (50:50) nanofluids through continuous 26h ultrasonication. The effect of nanoparticle concentration (0 to 0.2 vol%) and temperature (25°C to 60°C) on the thermal conductivity of the nanofluids was investigated. The results clearly indicate that an increase in the nanoparticle concentration increases the thermal conductivity of the nanofluid. Similarly the thermal conductivity of the nanofluid increases with increase in temperature. The enhanced thermal conductivity in the nanofluids may be due to either or both, the Brownian movement and the nano-interfacial layering. The maximum enhancement of 16% was obtained at 0.2 vol% nanoparticle concentration and at 60°C. An accurate correlation, modeling the thermal conductivity as a function of nanoparticle concentration and temperature was also proposed based on the experimental data.

Occurrence of fecal coliform bacteria in selected streams in Wyoming, 1990-99

USGS Publications Warehouse

Clark, Melanie L.; Norris, Jodi R.

2000-01-01

The U.S. Geological Survey (USGS), in cooperation with the Wyoming Department of Environmental Quality (WDEQ), is collecting water samples for analysis of fecal coliform bacteria at 18 stream sites as part of a statewide network. Contamination by bacteria of fecal origin in streams where contact recreation is a designated water use is a concern because of potential public-health risk from the presence of enteric pathogens. Fecal coliform concentrations are temporally and spatially variable in Wyoming streams-concentrations ranged from less than 1 to 45,000 colonies per 100 milliliters of water during 1990-99. Fecal coliform concentrations were less than the water-quality criterion of 400 colonies per 100 milliliters in 83 percent of the samples, indicating fecal coliform contamination is not a widespread problem in these Wyoming streams. However, 14 of the 18 monitoring sites had at least one sample in which the fecal coliform concentration exceeded 400 colonies per 100 milliliters at some time during the 10-year period. Fecal coliform concentrations generally are higher during April through September than during October through March. The higher concentrations coincide with the time period when the public-health risk is higher because summer months are when contact recreation use is more likely occurring. Fecal coliform concentrations were positively correlated with discharge and stream temperature and generally were negatively correlated with pH, specific conductance, and dissolved oxygen.

Quality of ground water in the Columbia Basin, Washington, 1983

DOE Office of Scientific and Technical Information (OSTI.GOV)

Turney, G.L.

1986-01-01

Groundwater from 188 sites in the Columbia Basin of central Washington was sampled and analyzed in 1983 for pH, specific conductance, and concentrations of fecal coliform bacteria, major dissolved ions, and dissolved iron, manganese, and nitrate. Twenty of the samples were also analyzed for concentrations of dissolved trace metals including aluminum, arsenic, barium, cadmium, chromium, copper, lead, mercury, selenium, silver, and zinc. The predominant water types were sodium bicarbonate and calcium bicarbonate. The sodium bicarbonate water samples had higher pH, fluoride, and sodium:adsorption ratio values than samples with other water types. Most trace metal concentrations were also < 10 ug/Lmore » except for barium and zinc, which had maximum concentrations of 170 and 600 ug/L, respectively. Nitrate concentrations were < 1.0 mg/L in water from more than half the wells sampled. US EPA (Environmental Protection Agency) drinking water regulations were exceeded in several samples, most commonly involving pH and concentrations of fluoride, nitrate, and dissolved solids in samples from Adams and Grant Counties. Generally, the historical data lead to similar conclusions about the quality of groundwater in the Columbia Basin region. However, historical samples had higher dissolved solids concentrations in Douglas County. Historical samples also included fewer sodium bicarbonate type waters in the region as a whole than the 1983 samples. 24 refs., 2 figs., 4 tabs.« less

Concentrations of strontium, barium, cadmium, copper, zinc, manganese, chromium, antimony, selenium, and lead in the liver and kidneys of dogs according to age, gender, and the occurrence of chronic kidney disease

PubMed Central

Mainzer, Barbara; Lahrssen-Wiederholt, Monika; Schafft, Helmut; Palavinskas, Richard; Breithaupt, Angele; Zentek, Jürgen

2015-01-01

This study was conducted to measure the concentrations of strontium (Sr), barium (Ba), cadmium (Cd), copper (Cu), zinc (Zn), manganese (Mn), chromium (Cr), antimony (Sb), selenium (Se), and lead (Pb) in canine liver, renal cortex, and renal medulla, and the association of these concentrations with age, gender, and occurrence of chronic kidney disease (CKD). Tissues from 50 dogs were analyzed using inductively coupled plasma mass spectrometry. Cu, Zn, and Mn levels were highest in the liver followed by the renal cortex and renal medulla. The highest Sr, Cd, and Se concentrations were measured in the renal cortex while lower levels were found in the renal medulla and liver. Female dogs had higher tissue concentrations of Sr (liver and renal medulla), Cd (liver), Zn (liver and renal cortex), Cr (liver, renal cortex, and renal medulla), and Pb (liver) than male animals. Except for Mn and Sb, age-dependent variations were observed for all element concentrations in the canine tissues. Hepatic Cd and Cr concentrations were higher in dogs with CKD. In conclusion, the present results provide new knowledge about the storage of specific elements in canine liver and kidneys, and can be considered important reference data for diagnostic methods and further investigations. PMID:25234328

Nano-metal oxides: Exposure and engineering control assessment.

PubMed

Garcia, Alberto; Eastlake, Adrienne; Topmiller, Jennifer L; Sparks, Christopher; Martinez, Kenneth; Geraci, Charles L

2017-09-01

In January 2007, the National Institute for Occupational Safety and Health (NIOSH) conducted a field study to evaluate process specific emissions during the production of ENMs. This study was performed using the nanoparticle emission assessment technique (NEAT). During this study, it was determined that ENMs were released during production and cleaning of the process reactor. Airborne concentrations of silver, nickel, and iron were found both in the employee's personal breathing zone and area samples during reactor cleaning. At the completion of this initial survey, it was suggested that a flanged attachment be added to the local exhaust ventilation system.  NIOSH re-evaluated the facility in December 2011 to assess worker exposures following an increase in production rates. This study included a fully comprehensive emissions, exposure, and engineering control evaluation of the entire process. This study made use of the nanoparticle exposure assessment technique (NEAT 2.0). Data obtained from filter-based samples and direct reading instruments indicate that reactor cleanout increased the overall particle concentration in the immediate area. However, it does not appear that these concentrations affect areas outside of the production floor. As the distance between the reactor and the sample location increased, the observed particle number concentration decreased, creating a concentration gradient with respect to the reactor. The results of this study confirm that the flanged attachment on the local exhaust ventilation system served to decrease exposure potential.  Given the available toxicological data of the metals evaluated, caution is warranted. One should always keep in mind that occupational exposure levels were not developed specifically for nanoscale particles. With data suggesting that certain nanoparticles may be more toxic than the larger counterparts of the same material; employers should attempt to control emissions of these particles at the source, to limit the potential for exposure.

Source-specific sewage pollution detection in urban river waters using pharmaceuticals and personal care products as molecular indicators.

PubMed

Kiguchi, Osamu; Sato, Go; Kobayashi, Takashi

2016-11-01

Source-specific elucidation of domestic sewage pollution caused by various effluent sources in an urban river water, as conducted for this study, demands knowledge of the relation between concentrations of pharmaceuticals and personal care products (PPCPs) as molecular indicators (caffeine, carbamazepine, triclosan) and water quality concentrations of total nitrogen (T-N) and total phosphorous (T-P). River water and wastewater samples from the Asahikawa River Basin in northern Japan were analyzed using derivatization-gas chromatography/mass spectrometry. Caffeine, used as an indicator of domestic sewage in the Asahikawa River Basin, was more ubiquitous than either carbamazepine or triclosan (92-100 %). Its concentration was higher than any target compound used to assess the basin: <4.4-370 ng/L for caffeine, <0.6-3.9 ng/L for carbamazepine, and <1.1-13 ng/L for triclosan. Higher caffeine concentrations detected in wastewater effluents and the strongly positive mutual linear correlation between caffeine and T-N or T-P (R 2  > 0.759) reflect the contribution of septic tank system effluents to the lower Asahikawa River Basin. Results of relative molecular indicators in combination with different molecular indicators (caffeine/carbamazepine and triclosan/carbamazepine) and cluster analysis better reflect the contribution of sewage than results obtained using concentrations of respective molecular indicators and cluster analysis. Relative molecular indicators used with water quality parameters (e.g., caffeine/T-N ratio) in this study provide results more clearly, relatively, and quantitatively than results obtained using molecular indicators alone. Moreover, the caffeine/T-N ratio reflects variations of caffeine flux from effluent sources. These results suggest strongly relative molecular indicators are also useful indicators, reflecting differences in spatial contributions of domestic sources for PPCPs in urban areas.

The indoor volatile organic compound (VOC) characteristics and source identification in a new university campus in Tianjin, China.

PubMed

Kang, Jian; Liu, Junjie; Pei, Jingjing

2017-06-01

This study investigates the volatile organic compounds (VOCs) constituents and concentration levels on a new university campus, where all of the buildings including classrooms and student dormitories were newly built and decorated within 1 year. Investigated indoor environments include dormitories, classrooms, and the library. About 30 dormitory buildings with different furniture loading ratios were measured. The characteristics of the indoor VOCs species are analyzed and possible sources are identified. The VOCs were analyzed with gas chromatography-mass spectroscopy (GC-MS). It was found that the average total VOC (TVOC) concentration can reach 2.44 mg/m 3 . Alkenes were the most abundant VOCs in dormitory rooms, contributing up to 86.5% of the total VOCs concentration. The concentration of α-pinene is the highest among the alkenes. Unlike the dormitory rooms, there is almost no room with TVOC concentration above 0.6 mg/m 3 in classroom and library buildings. Formaldehyde concentration in the dormitory rooms increased about 23.7% after the installation of furniture, and the highest level reached 0.068 mg/m 3 . Ammonia released from the building antifreeze material results in an average indoor concentration of 0.28 mg/m 3 , which is 100% over the threshold and should be seriously considered. Further experiments were conducted to analyze the source of the α-pinene and some alkanes in dormitory rooms. The results showed that the α-pinene mainly comes from the bed boards, while the wardrobes are the main sources of alkanes. The contribution of the pinewood bed boards to the α-pinene and TVOC concentration can reach up to above 90%. The same type rooms were sampled 1 year later and the decay rate of α-pinene is quite high, close to 100%, so that it almost cannot be detected in the sampled rooms. Analysis of indoor volatile organic compounds (VOCs) in newly built campus buildings in China identified the specific constituents of indoor VOCs contaminants exposed to Chinese college students. The main detected substances α-pinene, β-pinene, and 3-carene originated from solid wood bed boards and should be seriously considered. In addition, the contribution rates of building structure materials and furniture to specific VOCs constituents are quantitative calculated. Also, the decay rates of these specific constituents within 1 year are also quantitative calculated in this paper. This study can help us to better understand the sources and concentration levels of VOC contaminants in campus buildings, and to help select appropriate materials in buildings.

Contaminant concentration versus flow velocity: drivers of biodegradation and microbial growth in groundwater model systems.

PubMed

Grösbacher, Michael; Eckert, Dominik; Cirpka, Olaf A; Griebler, Christian

2018-06-01

Aromatic hydrocarbons belong to the most abundant contaminants in groundwater systems. They can serve as carbon and energy source for a multitude of indigenous microorganisms. Predictions of contaminant biodegradation and microbial growth in contaminated aquifers are often vague because the parameters of microbial activity in the mathematical models used for predictions are typically derived from batch experiments, which don't represent conditions in the field. In order to improve our understanding of key drivers of natural attenuation and the accuracy of predictive models, we conducted comparative experiments in batch and sediment flow-through systems with varying concentrations of contaminant in the inflow and flow velocities applying the aerobic Pseudomonas putida strain F1 and the denitrifying Aromatoleum aromaticum strain EbN1. We followed toluene degradation and bacterial growth by measuring toluene and oxygen concentrations and by direct cell counts. In the sediment columns, the total amount of toluene degraded by P. putida F1 increased with increasing source concentration and flow velocity, while toluene removal efficiency gradually decreased. Results point at mass transfer limitation being an important process controlling toluene biodegradation that cannot be assessed with batch experiments. We also observed a decrease in the maximum specific growth rate with increasing source concentration and flow velocity. At low toluene concentrations, the efficiencies in carbon assimilation within the flow-through systems exceeded those in the batch systems. In all column experiments the number of attached cells plateaued after an initial growth phase indicating a specific "carrying capacity" depending on contaminant concentration and flow velocity. Moreover, in all cases, cells attached to the sediment dominated over those in suspension, and toluene degradation was performed practically by attached cells only. The observed effects of varying contaminant inflow concentration and flow velocity on biodegradation could be captured by a reactive-transport model. By monitoring both attached and suspended cells we could quantify the release of new-grown cells from the sediments to the mobile aqueous phase. Studying flow velocity and contaminant concentrations as key drivers of contaminant transformation in sediment flow-through microcosms improves our system understanding and eventually the prediction of microbial biodegradation at contaminated sites.

An exposure study of bystanders and workers during the installation and removal of asbestos gaskets and packing.

PubMed

Mangold, Carl; Clark, Katherine; Madl, Amy; Paustenbach, Dennis

2006-02-01

From 1982 until 1991, a series of studies was performed to evaluate the airborne concentration of chrysotile asbestos associated with replacing gaskets and packing materials. These studies were conducted by the senior author in response to concerns raised by a report from the Navy in 1978 on asbestos exposures associated with gasket work. A series of studies was conducted because results of those who worked with gaskets within the Navy study did not address the background concentrations of asbestos in the work areas, which may have been significant due to the presence of asbestos insulation in the ships and shipyards. The intent of the studies performed from 1982 through 1991 was to re-create the Navy's work practices in a contaminant-free environment during an 8-hour workday (so the data could be compared with the OSHA permissible exposure limit [PEL]). Samples were collected to characterize personal and area airborne asbestos concentrations associated with the formation, removal, and storage of gaskets, as well as the scraping of flanges and the replacement of valve packing. The results indicate that the 8-hour time-weighted average (TWA) exposures of pipefitters and other tradesmen who performed these activities were below the current PEL and all previous PELs. Specifically, the highest average 8-hour TWA concentration measured for workers manipulating asbestos gaskets during this study was 0.030 f/cc (during gasket removal and flange face scraping onboard a naval ship). Likewise, the 8-hour TWA breathing zone concentrations of a worker removing and replacing asbestos valve packing did not exceed 0.016 f/cc. In most cases, the concentrations were not distinguishable from ambient levels of asbestos in the ships or the general environment. These results are not surprising given that asbestos fibers in gasket materials are encapsulated within a binder.

Summary and interpretation of discrete and continuous water-quality monitoring data, Mattawoman Creek, Charles County, Maryland, 2000-11

USGS Publications Warehouse

Chanat, Jeffrey G.; Miller, Cherie V.; Bell, Joseph M.; Majedi, Brenda Feit; Brower, David P.

2013-01-01

Discrete samples and continuous (15-minute interval) water-quality data were collected at Mattawoman Creek (U.S. Geological Survey station number 01658000) from October 2000 through January 2011, in cooperation with the Charles County (Maryland) Department of Planning and Growth Management, the Maryland Department of the Environment, and the Maryland Geological Survey. Mattawoman Creek is a fourth-order Maryland tributary to the tidal freshwater Potomac River; the creek’s watershed is experiencing development pressure due to its proximity to Washington, D.C. Data were analyzed for the purpose of describing ambient water quality, identifying potential contaminant sources, and quantifying nutrient and sediment loads to the tidal freshwater Mattawoman estuary. Continuous data, collected at 15-minute intervals, included discharge, derived from stage measurements made using a pressure transducer, as well as water temperature, pH, specific conductance, dissolved oxygen, and turbidity, all measured using a water-quality sonde. In addition to the continuous data, a total of 360 discrete water-quality samples, representative of monthly low-flow and targeted storm conditions, were analyzed for suspended sediment and nutrients. Continuous observations gathered by a second water-quality sonde, which was temporarily deployed in 2011 for quality-control purposes, indicated substantial lateral water-quality gradients due to inflow from a nearby tributary, representing about 10 percent of the total gaged area upstream of the sampling location. These lateral gradients introduced a time-varying bias into both the continuous and discrete data, resulting in observations that were at some times representative of water-quality conditions in the main channel and at other times biased towards conditions in the tributary. Despite this limitation, both the continuous and discrete data provided insight into the watershed-scale factors that influence water quality in Mattawoman Creek. Annual precipitation over the study period was representative of the long-term record for southern Maryland. The median value of continuously measured discharge was 25 cubic feet per second (ft3/s), and the maximum observed value was 3,210 ft3/s; there were 498 days, or about 15 percent of the study period, when flow was zero or too low to measure. Continuously measured water temperature followed a seasonal trend characteristic of the geographic setting; the trend in dissolved oxygen was inverted relative to temperature, and reflected nearly saturated conditions year round. Relations between discharge and both pH and specific conductance indicate that stream water can be conceptualized as a mixture of acidic, dilute precipitation with pH-neutral groundwater of higher conductance. Specific conductance data showed a pronounced winter peak in both median and extreme measurements, indicating the influence of road salt. However, this influence is minor relative to that observed in the Northeast Branch Anacostia River (U.S. Geological Survey station number 01649500), a nearby, more heavily urbanized comparison basin. The median suspended-sediment concentration in discrete samples was 24 milligrams per liter (mg/L), with minimum and maximum concentrations of 1 mg/L and 2,890 mg/L, respectively. Total nitrogen ranged from 0.21 mg/L to 4.09 mg/L, with a median of 0.69 mg/L; total phosphorus ranged from less than 0.01 mg/L to 0.98 mg/L, with a median of 0.07 mg/L. Total nitrogen was dominated by the dissolved organic fraction (49 percent based on median species concentrations); total phosphorus was predominantly particulate (70 percent). Seasonal trends in suspended-sediment concentration indicate a supply subsidy in late winter and spring; this could be linked to flood-plain interaction, mobilization of sediment from the channel or banks, or anthropogenic input. Seasonal trends for both total phosphorus and total nitrogen generally corresponded to seasonal trends for suspended sediment, indicating a common underlying physical control, likely acting in synchrony with seasonal biological controls on total nutrient concentrations. Speciation of phosphorus, including proportional concentration of the biologically available dissolved inorganic fraction, did not vary seasonally. The speciation of nitrogen reflected demand for inorganic nitrogen and associated transformation into organic nitrogen during the growing season. Stepwise regression models were developed, using continuous data corresponding to collection times for discrete samples as candidate surrogates for suspended sediment, total phosphorus, and total nitrogen. Turbidity and discharge were both included in the model for suspended sediment (R2 = 0.76, n = 185); only turbidity was selected as a robust predictor of total phosphorus and nitrogen (R2 = 0.68 and 0.61, respectively, n = 186 for both). Loads of sediment and nutrients to the downstream Mattawoman estuary were computed using the U.S. Geological Survey computer program LOADEST. Load estimation included comparison of a routinely applied seven-parameter regression model based on time, season, and discharge, with an eight-parameter model that also includes turbidity. Adding turbidity decreased total load estimates, based on hourly data for a fixed 2-month period, by 21, 8, and 3 percent for suspended sediment, total phosphorus, and total nitrogen, respectively, in addition to decreasing the standard error of prediction for all three constituents. The seasonal pattern in specific conductance, reflecting road salt application, is the strongest evidence of the effect of upstream development on water quality at Mattawoman Creek. Accordingly, ongoing continuous monitoring for trends in specific conductance would be the most reliable means of detecting further degradation associated with increased development.

Assessment of Determinants of Emission Potentially Affecting the Concentration of Airborne Nano-Objects and Their Agglomerates and Aggregates.

PubMed

Bekker, Cindy; Fransman, Wouter; Boessen, Ruud; Oerlemans, Arné; Ottenbros, Ilse B; Vermeulen, Roel

2017-01-01

Nano-specific inhalation exposure models could potentially be effective tools to assess and control worker exposure to nano-objects, and their aggregates and agglomerates (NOAA). However, due to the lack of reliable and consistent collected NOAA exposure data, the scientific basis for validation of the existing NOAA exposure models is missing or limited. The main objective of this study was to gain more insight into the effect of various determinants underlying the potential on the concentration of airborne NOAA close to the source with the purpose of providing a scientific basis for existing and future exposure inhalation models. Four experimental studies were conducted to investigate the effect of 11 determinants of emission on the concentration airborne NOAA close to the source during dumping of ~100% nanopowders. Determinants under study were: nanomaterial, particle size, dump mass, height, rate, ventilation rate, mixing speed, containment, particle surface coating, moisture content of the powder, and receiving surface. The experiments were conducted in an experimental room (19.5 m3) with well-controlled environmental and ventilation conditions. Particle number concentration and size distribution were measured using real-time measurement devices. Dumping of nanopowders resulted in a higher number concentration and larger particles than dumping their reference microsized powder (P < 0.05). Statistically significant more and larger particles were also found during dumping of SiO2 nanopowder compared to TiO2/Al2O3 nanopowders. Particle surface coating did not affect the number concentration but on average larger particles were found during dumping of coated nanopowders. An increase of the powder's moisture content resulted in less and smaller particles in the air. Furthermore, the results indicate that particle number concentration increases with increasing dump height, rate, and mass and decreases when ventilation is turned on. These results give an indication of the direction and magnitude of the effect of the studied determinants on concentrations close to the source and provide a scientific basis for (further) development of existing and future NOAA inhalation exposure models. © The Author 2017. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.