Accumulation of steroid hormones in soil and its adjacent aquatic environment from a typical intensive vegetable cultivation of North China.

PubMed

Zhang, Feng-Song; Xie, Yun-Feng; Li, Xue-Wen; Wang, Dai-Yi; Yang, Lin-Sheng; Nie, Zhi-Qiang

2015-12-15

Steroid hormones released from manure agricultural application are a matter of global concern. The residual levels of steroid hormones were studied in a typical intensive vegetable cultivation area in northeast China, with a long history of heavy manure application. Seven steroids (estrone, 17α-estradiol, 17β-estradiol, estriol, testosterone, androstendione and progesterone) were analyzed from soil sampled from vegetable greenhouses, from sediments and water from the adjacent drainage ditch and from the groundwater. The results showed that target steroids were detected in the soil samples, with detection frequencies varying from 3.13 to 100%. The steroid concentrations varied substantially in soils, ranging from below the detection limit to 109.7μg·kg(-1). Three steroids-progesterone, androstendione and estrone-were found to have relatively high residue concentrations in soil, with maximum concentrations of 109.7, 9.83 and 13.30μg·kg(-1), respectively. In adjacent groundwater, all the steroids, with the exception of estrone, were detected in one or more of the 13 groundwater samples. The concentrations of steroids in groundwater ranged from below the method detection limit to 2.38ng·L(-1). Six of the seven (excluding androstendione) were detected in drainage ditch water samples, with concentrations ranging from below the detection limit to 14ng·L(-1). Progesterone, androstendione and estrone accumulated relatively easily in soils; their concentrations in groundwater were lower than those of other steroids. The concentrations of testosterone and estriol were relatively low in soil, while in groundwater were higher than those of other steroids. The residual levels of steroids in soil and groundwater showed a clear spatial variation in the study area. The residual levels of steroid hormones in soil varied substantially between differently planted greenhouses. Copyright © 2015. Published by Elsevier B.V.

Uptake of aldehydes and ketones at typical indoor concentrations by houseplants.

PubMed

Tani, Akira; Hewitt, C Nicholas

2009-11-01

The uptake rates of low-molecular weight aldehydes and ketones by peace lily (Spathiphyllum clevelandii) and golden pothos (Epipremnum aureum) leaves at typical indoor ambient concentrations (10(1)-10(2) ppbv) were determined. The C3-C6 aldehydes and C4-C6 ketones were taken up by the plant leaves, but the C3 ketone acetone was not. The uptake rate normalized to the ambient concentration C(a) ranged from 7 to 19 mmol m(-2) s(-1) and from 2 to 7 mmol m(-2) s(-1) for the aldehydes and ketones, respectively. Longer-term fumigation results revealed that the total uptake amounts were 30-100 times as much as the amounts dissolved in the leaf, suggesting that volatile organic carbons are metabolized in the leaf and/or translocated through the petiole. The ratio of the intercellular concentration to the external (ambient) concentration (C(i)/C(a)) was significantly lower for most aldehydes than for most ketones. In particular, a linear unsaturated aldehyde, crotonaldehyde, had a C(i)/C(a) ratio of approximately 0, probably because of its highest solubility in water.

Studies on utilization of treated stack gas. II. Growth of water hyacinths (Eichhornia crassipes) in carbon dioxide-rich atmospheres

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

Martin, D.F.; Hewes, K.A.

1984-01-01

Water hyacinths survive atmospheric carbon dioxide concentrations ranging from ambient to 15% (v/v). The optimum growth during a one-week period with continuous laboratory lighting (200 ..mu..Es/m/sup 2//sec) appeared to be about 10%. Under these conditions, the equation defining inorganic carbon fixed as a function of the atmospheric concentration of carbon dioxide indicated a maximum of about 75% of available carbon was fixed over the range 1-10% CO/sub 2/. Under a typical light cycle, the percent fixed was reduced to about 60%. The implications of the results are considered.

Change in soluble phosphorus in soils following fertilization is dependent on initial Mehlich-3 phosphorus.

PubMed

Bond, C Ryan; Maguire, R O; Havlin, J L

2006-01-01

There is a lack of information on how fertilization and initial Mehlich-3 phosphorus (M3P) interact to affect water soluble P (WSP) in soils. Our objectives were to (i) quantify the relationship between WSP and M3P for four textural diverse benchmark soils of North Carolina (NC) and (ii) quantify the change in WSP concentrations following P additions to soils over a wide range of initial M3P. Soils known to represent a wide range in M3P were collected from an Autryville loamy sand (loamy, siliceous, subactive, thermic Arenic Paleudults), Wasda muck (fine-loamy, mixed, semiactive, acid, thermic Histic Humaquepts), Georgeville silt loam (fine, kaolinitic, thermic Typic Kanhapludults), and Pacolet sandy clay loam (fine, kaolinitic, thermic Typic Kanhapludults) and analyzed for M3P, Fe, Al, and WSP. An incubation study was also conducted where four samples representing a range in M3P from each series were fertilized at rates of 150 and 300 kg P ha(-1), and WSP was measured at 1, 7, and 21 d after fertilization. The Wasda muck exhibited a change point at 115 mg P kg(-1) across a broad range of M3P concentrations (60-238 mg kg(-1)) while Autryville, Georgeville, and Pacolet series (with ranges in M3P of 32-328, 119-524, 0-1034 mg P kg(-1), respectively) maintained linear relationships between WSP and M3P. For the fertilized soils, significant increases in WSP occurred regardless of P rate. Yet, WSP concentrations were greater in soils with greater initial M3P. Thus, these data suggest that shifting animal waste applications to fields of relatively lower M3P concentrations would have an immediate impact on reducing risk for P losses, if all other factors are equal.

Macronutrient and boron ratios in tall fescue: relationship to yields on pyritic coal wastes

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

Lewis, B.G.

A previous greenhouse study had demonstrated that yield of tall fescue (Festuca arundinacea Schreb.) grown directly on a pyritic waste was not significantly different from yield on a soil despite low tissue concentrations of P and K in the waste-grown plants. In an attempt to explain this result, and to determine if this phenomenon was typical of such waste, a greenhouse study was carried out with pyritic waste from five disposal sites for coal-cleaning refuse in southern Illinois. The wastes and an agricultural soil (Eilliott silt loam: fine, illitic, mesic Aquic Arguidolls) were treated with limestone (to pH 6.5) andmore » fertilizers. Yields of 8-week-old shoots of tall fescue grown on the wastes were significantly lower than yield of plants grown on the soil when the Ca/B ratio in the shoots was outside a range of 1.7 to 2.8 (where Ca/B is the ratio of log/sub 10/ concentrations of Ca and B expressed as microgram-atoms per gram dry matter). Within this range, yields were not significantly different from yield on the soil despite significantly lower concentrations of P and K in the shoots of the waste-grown plants. It is suggested that elemental interactions should not be ignored in reclamation of waste sites, particularly where ''trace'' element concentrations are either higher or lower than concentrations in typical soils. Results also suggest a P- and K-sparing effect of elevated B concentrations in tall fescue. 23 references.« less

Amorphous In-Ga-Zn-O Powder with High Gas Selectivity towards Wide Range Concentration of C₂H₅OH.

PubMed

Chen, Hongxiang; Jiang, Wei; Zhu, Lianfeng; Yao, Youwei

2017-05-24

Amorphous indium gallium zinc oxide (a-IGZO) powder was prepared by typical solution-based process and post-annealing process. The sample was used as sensor for detecting C₂H₅OH, H₂, and CO. Gas-sensing performance was found to be highly sensitive to C₂H₅OH gas in a wide range of concentration (0.5-1250 ppm) with the response of 2.0 towards 0.5 ppm and 89.2 towards 1250 ppm. Obvious difference of response towards C₂H₅OH, H₂, and CO was found that the response e.g., was 33.20, 6.64, and 2.84 respectively at the concentration of 200 ppm. The response time and recovery time of was 32 s and 14 s respectively towards 200 ppm concentration of C₂H₅OH gas under heating voltage of 6.5 V.

Comparison of the properties of some synthetic crudes with petroleum crudes

NASA Technical Reports Server (NTRS)

Antoine, A. C.

1979-01-01

Physical properties and chemical compositions of six synthetic crudes were determined. The results were compared to those of typical petroleum crudes, with the interest being the feasibility of making jet fuels from oil shale and coal syncrudes. The specific gravity, viscosity, and pour point were measured, showing that these crudes would be described as heavier rather than lighter crudes. The boiling range distribution of the crudes was determined by distillation and by gas chromatography. In addition, gel permeation chromatograms were obtained, giving a unique molecular weight distribution profile for each crude. Analyses for carbon, hydrogen, nitrogen and sulfur concentrations were performed, as well as for hydrocarbon group type and trace element concentrations. It was found that the range in concentration of vanadium, an element whose presence in turbine fuels is of major concern, was lower than that of petroleum crudes. Sodium and potassium, other elements of concern, were present in comparatively high concentrations.

Cholesterol values in free-ranging gorillas (Gorilla gorilla gorilla and Gorilla beringei) and Bornean orangutans (Pongo pygmaeus).

PubMed

Schmidt, Debra A; Ellersieck, Mark R; Cranfield, Michael R; Karesh, William B

2006-09-01

Cholesterol concentrations in captive gorillas and orangutans vary widely within species and average approximately 244 mg/dl for gorillas and 169 mg/dl for orangutans as published previously. The International Species Inventory System reports higher concentrations of 275 and 199 mg/dl for gorillas and orangutans, respectively. It is unknown whether these values were typical, influenced by captive management, or both. To answer this question, banked serum samples from free-ranging mountain gorillas (Gorilla beringei), western lowland gorillas (Gorilla gorilla gorilla), and Bornean orangutans (Pongo pygmaeus) were analyzed for total cholesterol, triglyceride, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol concentrations. Mountain gorillas did not differ significantly from free-ranging western lowland gorillas in cholesterol, triglyceride, high-density lipoprotein cholesterol, or low-density lipoprotein cholesterol concentrations, indicating mountain gorilla values could be a model for western lowland gorillas. Captive gorilla total cholesterol and low-density lipoprotein cholesterol concentrations were significantly higher (P < 0.05) than in free-ranging groups. Triglyceride concentrations for captive gorillas were significantly higher (P < 0.05) than the male mountain and western lowland gorillas, but they were not significantly different from the female mountain gorillas. Captive orangutan total cholesterol concentrations were only higher (P < 0.05) than the free-ranging female orangutans, whereas captive orangutan low-density lipoprotein cholesterol concentrations were significantly higher (P < 0.05) than both free-ranging male and female orangutans. Calculated and measured low-density lipoprotein cholesterol concentrations were compared for all free-ranging animals and were significantly different (P < 0.05) for all groups, indicating Friedewald's equation for calculating low-density lipoprotein cholesterol is not appropriate for use with nonfasted apes. The higher total cholesterol and low-density lipoprotein cholesterol concentrations in captive apes may predispose them to cardiovascular disease and might be attributed to diets, limited energy expenditure, and genetics.

A comparison of geochemical exploration techniques and sample media within accretionary continental margins: an example from the Pacific Border Ranges, Southern Alaska, U.S.A.

USGS Publications Warehouse

Sutley, S.J.; Goldfarb, R.J.; O'Leary, R. M.; Tripp, R.B.

1990-01-01

The Pacific Border Ranges of the southern Alaskan Cordillera are composed of a number of allochthonous tectonostratigraphic terranes. Within these terranes are widespread volcanogenic, massive sulfide deposits in and adjacent to portions of accreted ophiolite complexes, bands and disseminations of chromite in accreted island-arc ultramafic rocks, and epigenetic, gold-bearing quartz veins in metamorphosed turbidite sequences. A geochemical pilot study was undertaken to determine the most efficient exploration strategy for locating these types of mineral deposits within the Pacific Border Ranges and other typical convergent continental margin environments. High-density sediment sampling was carried out in first- and second-order stream channels surrounding typical gold, chromite and massive sulfide occurrences. At each site, a stream-sediment and a panned-concentrate sample were collected. In the laboratory, the stream sediments were sieved into coarse-sand, fine- to medium-sand, and silt- to clay-size fractions prior to analysis. One split of the panned concentrates was retained for analysis; a second split was further concentrated by gravity separation in heavy liquids and then divided into magnetic, weakly magnetic and nonmagnetic fractions for analysis. A number of different techniques including atomic absorption spectrometry, inductively coupled plasma atomic emission spectrometry and semi-quantitative emission spectrography were used to analyze the various sample media. Comparison of the various types of sample media shows that in this tectonic environment it is most efficient to include a silt- to clay-size sediment fraction and a panned-concentrate sample. Even with the relatively low detection limits for many elements by plasma spectrometry and atomic absorption spectrometry, anomalies reflecting the presence of gold veins could not be identified in any of the stream-sediment fractions. Unseparated panned-concentrate samples should be analyzed by emission spectroscopy and atomic absorption spectrometry for Ag and Au. If, however, magnetic and nonmagnetic concentrate fractions are used in a reconnaissance program, semiquantitative emission spectrography is adequate for all analytical work. ?? 1990.

Measuring calcium, potassium, and nitrate in plant nutrient solutions using ion-selective electrodes in hydroponic greenhouse of some vegetables.

PubMed

Vardar, Gökay; Altıkatoğlu, Melda; Ortaç, Deniz; Cemek, Mustafa; Işıldak, İbrahim

2015-01-01

Generally, the life cycle of plants depends on the uptake of essential nutrients in a balanced manner and on toxic elements being under a certain concentration. Lack of control of nutrient levels in nutrient solution can result in reduced plant growth and undesired conditions such as blossom-end rot. In this study, sensitivity and selectivity tests for various polyvinylchloride (PVC)-based ion-selective membranes were conducted to identify those suitable for measuring typical concentration ranges of macronutrients, that is, NO(3-), K(+), and Ca(2+), in hydroponic solutions. The sensitivity and selectivity of PVC-membrane-based ion-selective sensors prepared with tetradodecylammoniumnitrate for NO(3-), valinomycin for K(+), and Ca ionophore IV for Ca(2+) were found to be satisfactory for measuring NO(3-), K(+), and Ca(2+) ions in nutrient solutions over typical ranges of hydroponic concentrations. Potassium, calcium, and nitrate levels that were utilized by cucumber and tomato seedlings in the greenhouse were different. The findings show that tomato plants consumed less amounts of nitrate than cucumber plants over the first 2 months of their growth. We also found that the potassium intake was higher than other nutritional elements tested for all plants. © 2014 International Union of Biochemistry and Molecular Biology, Inc.

Application of time-division-multiplexed lasers for measurements of gas temperature and CH4 and H2O concentrations at 30 kHz in a high-pressure combustor.

PubMed

Caswell, Andrew W; Kraetschmer, Thilo; Rein, Keith; Sanders, Scott T; Roy, Sukesh; Shouse, Dale T; Gord, James R

2010-09-10

Two time-division-multiplexed (TDM) sources based on fiber Bragg gratings were applied to monitor gas temperature, H(2)O mole fraction, and CH(4) mole fraction using line-of-sight absorption spectroscopy in a practical high-pressure gas turbine combustor test article. Collectively, the two sources cycle through 14 wavelengths in the 1329-1667 nm range every 33 μs. Although it is based on absorption spectroscopy, this sensing technology is fundamentally different from typical diode-laser-based absorption sensors and has many advantages. Specifically, the TDM lasers allow efficient, flexible acquisition of discrete-wavelength information over a wide spectral range at very high speeds (typically 30 kHz) and thereby provide a multiplicity of precise data at high speeds. For the present gas turbine application, the TDM source wavelengths were chosen using simulated temperature-difference spectra. This approach is used to select TDM wavelengths that are near the optimum values for precise temperature and species-concentration measurements. The application of TDM lasers for other measurements in high-pressure, turbulent reacting flows and for two-dimensional tomographic reconstruction of the temperature and species-concentration fields is also forecast.

Influence of external factors on the self-assembly of two structurally related antidepressant drugs: a thermodynamic study

NASA Astrophysics Data System (ADS)

Gutiérrez-Pichel, Manuel; Attwood, David; Taboada, Pablo; Mosquera, Víctor

Apparent molal volumes and adiabatic compressibilities of aqueous solutions of the amphiphilic antidepressant drugs imipramine and desipramine hydrochlorides have been determined from density and ultrasound velocity measurements in the temperature range 288.15-313.15 K in buffered solution of pH 3.0 and 5.5. Critical concentrations for aggregation of these drugs were obtained from inflections on the plots of the sound velocity against drug concentration. Positive deviation from the Debye-Hückel limiting law of the apparent molal volume of imipramine provides evidence of limited association at concentrations below the critical concentration over the temperature range studied. Apparent molal adiabatic compressibilities of the aggregates formed by the drugs, calculated by combining the ultrasound velocity and density data, were typical of those for a stacked aggregate. The critical concentration and energy involved in the aggregation process of these drugs have been evaluated using isothermal titration calorimetry. The solvent-aggregate interactions have been discussed from compressibility and calorimetry data.

Water and sediment quality of the Lake Andes and Choteau Creek basins, South Dakota, 1983-2000

USGS Publications Warehouse

Sando, Steven Kent; Neitzert, Kathleen M.

2003-01-01

The Bureau of Reclamation has proposed construction of the Lake Andes/Wagner Irrigation Demonstration Project to investigate environmental effects of irrigation of glacial till soils substantially derived from marine shales. During 1983-2000, the U.S. Geological Survey collected hydrologic, water-quality, and sediment data in the Lake Andes and Choteau Creek Basins, and on the Missouri River upstream and downstream from Choteau Creek, to provide baseline information in support of the proposed demonstration project. Lake Andes has a drainage area of about 230 mi2 (square miles). Tributaries to Lake Andes are ephemeral. Water-level fluctuations in Lake Andes can be large, and the lake has been completely dry on several occasions. The outlet aqueduct from Lake Andes feeds into Garden Creek, which enters Lake Francis Case just upstream from Fort Randall Dam on the Missouri River. For Lake Andes tributary stations, calcium, magnesium, and sodium are approximately codominant among the cations, and sulfate is the dominant anion. Dissolved-solids concentrations typically range from about 1,000 mg/L (milligrams per liter) to about 1,700 mg/L. Major-ion concentrations for Lake Andes tend to be higher than the tributaries and generally increase downstream in Lake Andes. Proportions of major ions are similar among the different lake units (with the exception of Owens Bay), with calcium, magnesium, and sodium being approximately codominant among cations, and sulfate being the dominant anion. Owens Bay is characterized by a calcium sulfate water type. Dissolved-solids concentrations for Lake Andes typically range from about 1,400 to 2,000 mg/L. Whole-water nitrogen and phosphorus concentrations are similar among the Lake Andes tributaries, with median whole-water nitrogen concentrations ranging from about 1.6 to 2.4 mg/L, and median whole-water phosphorus concentrations ranging from about 0.5 to 0.7 mg/L. Whole-water nitrogen concentrations in Lake Andes are similar among the different units, with medians that range from about 2.4 to 4.0 mg/L. Median whole-water phosphorus concentrations for the different Lake Andes units range from 0.2 to 0.5 mg/L, and decrease downstream through Lake Andes. Median selenium concentrations are substantially lower for Andes Creek (3 ?g/L (micrograms per liter)) than for the other tributary stations (34, 18, and 7 ?g/L). Median selenium concentrations for the lake stations (ranging from less than 1 to 2 ?g/L) are substantially lower than tributary stations. The pesticides 2,4-D and atrazine were the most commonly detected pesticides in Lake Andes. Median concentrations for 2,4-D for Lake Andes range from 0.07 to 0.11 ?g/L; the median concentration for Owens Bay is 0.04 ?g/L. Median concentrations for atrazine for Lake Andes range from 0.2 to 0.4 ?g/L; the median concentration for Owens Bay is less than 0.1 ?g/L. Concentrations of both 2,4-D and atrazine are largest for the most upstream part of Lake Andes that is most influenced by tributary inflow. Median suspended-sediment concentrations for Lake Andes tributaries range from 22 to 56 mg/L. Most of the suspended sediment transported in the Lake Andes tributaries consists of particles less than 63 ?m (micrometers) in diameter. Concentrations of most constituents in bottom sediments generally had similar ranges and medians for the Lake Andes tributaries. However, Andes Creek generally had lower concentrations of several metals. For Lake Andes, medians and ranges for most constituents generally were similar among the different units. However, selenium concentrations tended to be higher in the upstream part of the lake, and generally decreased downstream. Results of vertical sediment cores collected from a single site in the South Unit of Lake Andes in October 2000 indicate that selenium loading to Lake Andes increased during the period 1952 through 2000. Choteau Creek has a drainage area of 619 mi2. In the upstream part of the basin, Chotea

Colorimetric nanoplasmonic assay to determine purity and titrate extracellular vesicles.

PubMed

Maiolo, Daniele; Paolini, Lucia; Di Noto, Giuseppe; Zendrini, Andrea; Berti, Debora; Bergese, Paolo; Ricotta, Doris

2015-04-21

Extracellular Vesicles (EVs) - cell secreted vesicles that carry rich molecular information of the parental cell and constitute an important mode of intercellular communication - are becoming a primary topic in translational medicine. EVs (that comprise exosomes and microvesicles/microparticles) have a size ranging from 40 nm to 1 μm and share several physicochemical proprieties, including size, density, surface charge, and light interaction, with other nano-objects present in body fluids, such as single and aggregated proteins. This makes separation, titration, and characterization of EVs challenging and time-consuming. Here we present a cost-effective and fast colorimetric assay for probing by eye protein contaminants and determine the concentration of EV preparations, which exploits the synergy between colloidal gold nanoplasmonics, nanoparticle-protein corona, and nanoparticle-membrane interaction. The assay hits a limit of detection of protein contaminants of 5 ng/μL and has a dynamic range of EV concentration ranging from 35 fM to 35 pM, which matches the typical range of EV concentration in body fluids. This work provides the first example of the exploitation of the nanoparticle-protein corona in analytical chemistry.

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

Maze, Grace M.

STREAM II is the aqueous transport model of the Weather Information Display (WIND) emergency response system at Savannah River Site. It is used to calculate transport in the event of a chemical or radiological spill into the waterways on the Savannah River Site. Improvements were made to the code (STREAM II V7) to include flow from all site tributaries to the Savannah River total flow and utilize a 4 digit year input. The predicted downstream concentrations using V7 were generally on the same order of magnitude as V6 with slightly lower concentrations and quicker arrival times when all onsite streammore » flows are contributing to the Savannah River flow. The downstream arrival time at the Savannah River Water Plant ranges from no change to an increase of 8.77%, with minimum changes typically in March/April and maximum changes typically in October/November. The downstream concentrations are generally no more than 15% lower using V7 with the maximum percent change in January through April and minimum changes in June/July.« less

Improving bioaerosol exposure assessments of composting facilities — Comparative modelling of emissions from different compost ages and processing activities

NASA Astrophysics Data System (ADS)

Taha, M. P. M.; Drew, G. H.; Tamer, A.; Hewings, G.; Jordinson, G. M.; Longhurst, P. J.; Pollard, S. J. T.

We present bioaerosol source term concentrations from passive and active composting sources and compare emissions from green waste compost aged 1, 2, 4, 6, 8, 12 and 16 weeks. Results reveal that the age of compost has little effect on the bioaerosol concentrations emitted for passive windrow sources. However emissions from turning compost during the early stages may be higher than during the later stages of the composting process. The bioaerosol emissions from passive sources were in the range of 10 3-10 4 cfu m -3, with releases from active sources typically 1-log higher. We propose improvements to current risk assessment methodologies by examining emission rates and the differences between two air dispersion models for the prediction of downwind bioaerosol concentrations at off-site points of exposure. The SCREEN3 model provides a more precautionary estimate of the source depletion curves of bioaerosol emissions in comparison to ADMS 3.3. The results from both models predict that bioaerosol concentrations decrease to below typical background concentrations before 250 m, the distance at which the regulator in England and Wales may require a risk assessment to be completed.

Lead distribution and possible sources along vertical zone spectrum of typical ecosystems in the Gongga Mountain, eastern Tibetan Plateau

NASA Astrophysics Data System (ADS)

Luo, Ji; Tang, Ronggui; Sun, Shouqin; Yang, Dandan; She, Jia; Yang, Peijun

2015-08-01

A total of 383 samples from soil, plant, litterfall and precipitation in four typical ecosystems of Gongga Mountain were collected. Pb concentrations of samples were measured and analyzed. The results showed mean Pb concentrations in different soil layers were in the order of O > A > C, and mean Pb concentrations of the aboveground parts of plant was 3.60 ± 2.54 mg kg-1, with the minimum value of 0.77 mg kg-1 and the maximum value of 10.90 mg kg-1. Pb concentrations in soil's O-horizon and A-horizon showed a downward trend with increasing elevation (the determination coefficient R2 was 0.9478, 0.7918 and 0.9759 respectively). In contrast to other soil layers, the level of Pb concentrations in O-horizon (incomplete decomposition) was significantly high. Litterfall decomposition, atmospheric deposition and the unique climate could be main factors leading high Pb accumulation in soil's O-horizon. What's more, significant correlation (R2 = 0.8126, P < 0.05) was found between Pb concentrations in fine roots and soil's A-horizon confirms that fine roots could adsorb and accumulate Pb materials in soil. In general, the fact that Pb inputted into the typical ecosystems in the Gongga Mountain via long-range transportation and deposition of the atmosphere from external Pb sources could be confirmed by the HYSPLIT model and the ratio of CPb/CAl in plants (leaves) and CPb/CAl in litterfall. The mining activities and increasing anthropogenic activities (tourism development) could be main sources of Pb in this area. In order to better understand Pb sources and eco-risks of these typical ecosystems, litterfall decomposition characteristics, biomass of productivity of forest ecosystem, Pb isotopic tracing among air mass, twigs, leaves, litterfall and O-horizon soil in this vertical belt should also be taken into consideration.

Determination of radon and radium concentrations in drinking water samples around the city of Kutahya.

PubMed

Sahin, Latife; Cetinkaya, Hakan; Murat Saç, Müslim; Içhedef, Mutlu

2013-08-01

The concentration of radium and radon has been determined in drinking water samples collected from various locations of Kutahya city, Turkey. The water samples are taken from public water sources and tap water, with the collector chamber method used to measure the radon and radium concentration. The radon concentration ranges between 0.1 and 48.6±1.7 Bq l(-1), while the radium concentration varies from a minimum detectable activity of <0.02-0.7±0.2 Bq l(-1) in Kutahya city. In addition to the radon and radium levels, parameters such as pH, conductivity and temperature of the water, humidity, pressure, elevation and the coordinates of the sampling points have also been measured and recorded. The annual effective dose from radon and radium due to typical water usage has been calculated. The resulting contribution to the annual effective dose due to radon ingestion varies between 0.3 and 124.2 μSv y(-1); the contribution to the annual effective dose due to radium ingestion varies between 0 and 143.3 μSv y(-1); the dose contribution to the stomach due to radon ingestion varies between 0.03 and 14.9 μSv y(-1). The dose contribution due to radon inhalation ranges between 0.3 and 122.5 μSv y(-1), assuming a typical transfer of radon in water to the air. For the overwhelming majority of the Kutahya population, it is determined that the average radiation exposure from drinking water is less than 73.6 µSv y(-1).

Organophosphate flame retardants in the indoor air and dust in cars in Japan.

PubMed

Tokumura, Masahiro; Hatayama, Rurika; Tatsu, Kouichi; Naito, Toshiyuki; Takeda, Tetsuya; Raknuzzaman, Mohammad; -Al-Mamun, Md Habibullah; Masunaga, Shigeki

2017-01-01

The concentrations of organophosphate flame retardants (OPFRs) in the indoor air and dust were measured in 25 unoccupied cars in Japan. In the indoor air of the cars, most OPFRs were neither detected nor found at a concentration lower than the method quantification limit. The highest concentration (1500 ng m -3 ) was obtained for tris(1-chloro-2-propyl) phosphate (TCIPP). By contrast, many OPFRs were detected in the dust samples collected from the interior of the cars. TCIPP and tris(2-ethylhexyl) phosphate (TEHP) were present at the highest concentrations at 390 μg g -1 (in dust from car seats) and 640 μg g -1 (in dust from car floor mats), respectively. The highest median concentrations (35 μg g -1 for car seats, 53 μg g -1 for car floor mats) were obtained for tris(2-butoxyethyl) phosphate (TBOEP). According to the results of our exposure assessment, the typical exposures to OPFRs via inhalation in car cabins ranged from 9.0×10 -4 to 7.8×10 -1 ng kg-bw -1 day -1 . The typical exposures to OPFRs via dust ingestion ranged from 9.2×10 -4 to 8.8×10 -1 ng kg-bw -1 day -1 . We compared these results with the ref-erence doses for OPFRs and found that, based on cur-rent information about the toxicities of OPFRs, exposure to OPFRs in car cabins via inhalation and dust ingestion is unlikely to have adverse human health effects.

The polycyclic aromatic hydrocarbon concentrations in soils in the Region of Valasske Mezirici, the Czech Republic

PubMed Central

2009-01-01

The polycyclic aromatic hydrocarbon (PAH) contamination of urban, agricultural and forest soil samples was investigated from samples obtained in the surroundings of Valasske Mezirici. Valasske Mezirici is a town located in the north-east mountainous part of the Czech Republic, where a coal tar refinery is situated. 16 PAHs listed in the US EPA were investigated. Organic oxidizable carbon was also observed in the forest soils. The PAH concentrations ranged from 0.86-10.84 (with one anomalous value of 35.14) and 7.66-79.39 mg/kg dm in the urban/agricultural and forest soils, respectively. While the PAH levels in the urban/agricultural soils are within the range typically found in industrialized areas, the forest soils showed elevated PAH concentrations compared to other forest soils in Western and Northern Europe. The PAH concentrations and their molecular distribution ratios were studied as functions of the sample location and the meteorological history. The soils from localities at higher altitudes above sea level have the highest PAH concentrations, and the PAH concentrations decrease with increasing distance from the town. PMID:20003407

The use of minimum selectable concentrations (MSCs) for determining the selection of antimicrobial resistant bacteria.

PubMed

Khan, Sadia; Beattie, Tara K; Knapp, Charles W

2017-03-01

The use of antimicrobial compounds is indispensable in many industries, especially drinking water production, to eradicate microorganisms. However, bacterial growth is not unusual in the presence of disinfectant concentrations that would be typically lethal, as bacterial populations can develop resistance. The common metric of population resistance has been based on the Minimum Inhibitory Concentration (MIC), which is based on bacteria lethality. However, sub-lethal concentrations may also select for resistant bacteria due to the differences in bacterial growth rates. This study determined the Minimal Selective Concentrations (MSCs) of bacterial populations exposed to free chlorine and monochloramine, representing a metric that possibly better reflects the selective pressures occurring at lower disinfectant levels than MIC. Pairs of phylogenetically similar bacteria were challenged to a range of concentrations of disinfectants. The MSCs of free chlorine and monochloramine were found to range between 0.021 and 0.39 mg L -1 , which were concentrations 1/250 to 1/5 than the MICs of susceptible bacteria (MIC susc ). This study indicates that sub-lethal concentrations of disinfectants could result in the selection of resistant bacterial populations, and MSCs would be a more sensitive indicator of selective pressure, especially in environmental systems.

Evaluation of Low-Gravity Smoke Particulate for Spacecraft Fire Detection

NASA Technical Reports Server (NTRS)

Urban, David; Ruff, Gary A.; Mulholland George; Meyer, Marit; Yuan, Zeng guang; Cleary, Thomas; Yang, Jiann; Greenberg, Paul; Bryg, Victoria

2013-01-01

Tests were conducted on the International Space Station to evaluate the smoke particulate size from materials and conditions that are typical of those expected in spacecraft fires. Five different materials representative of those found in spacecraft (Teflon, Kapton, cotton, silicone rubber and Pyrell) were heated to temperatures below the ignition point with conditions controlled to provide repeatable sample surface temperatures and air flow. The air flow past the sample during the heating period ranged from quiescent to 8 cm/s. The effective transport time to the measurement instruments was varied from 11 to 800 seconds to simulate different smoke transport conditions in spacecraft. The resultant aerosol was evaluated by three instruments which measured different moments of the particle size distribution. These moment diagnostics were used to determine the particle number concentration (zeroth moment), the diameter concentration (first moment), and the mass concentration (third moment). These statistics were combined to determine the diameter of average mass and the count mean diameter and by assuming a log-normal distribution, the geometric mean diameter and the geometric standard deviations were also calculated. Smoke particle samples were collected on TEM grids using a thermal precipitator for post flight analysis. The TEM grids were analyzed to determine the particle morphology and shape parameters. The different materials produced particles with significantly different morphologies. Overall the majority of the average smoke particle sizes were found to be in the 200 to 400 nanometer range with the quiescent cases and the cases with increased transport time typically producing with substantially larger particles. The results varied between materials but the smoke particles produced in low gravity were typically twice the size of particles produced in normal gravity. These results can be used to establish design requirements for future spacecraft smoke detectors.

Triclosan alterations of estuarine phytoplankton community structure.

PubMed

Pinckney, James L; Thompson, Laura; Hylton, Sarah

2017-06-15

Antimicrobial additives in pharmaceutical and personal care products are a major environmental concern due to their potential ecological impacts on aquatic ecosystems. Triclosan (TCS) has been used as an antiseptic, disinfectant, and preservative in various media. The sublethal and lethal effects of TCS on estuarine phytoplankton community composition were investigated using bioassays of natural phytoplankton communities to measure phytoplankton responses to different concentrations of TCS ranging from 1 to 200μgl -1 . The EC 50 (the concentration of an inhibitor where the growth is reduced by half) for phytoplankton groups (diatoms, chlorophytes, cryptophytes) examined in this ranged from 10.7 to 113.8μg TCS l -1 . Exposures resulted in major shifts in phytoplankton community composition at concentrations as low as 1.0μg TCS l -1 . This study demonstrates estuarine ecosystem sensitivity to TCS exposure and highlights potential alterations in phytoplankton community composition at what are typically environmental concentrations of TCS in urbanized estuaries. Copyright © 2017 Elsevier Ltd. All rights reserved.

Amorphous In–Ga–Zn–O Powder with High Gas Selectivity towards Wide Range Concentration of C2H5OH

PubMed Central

Chen, Hongxiang; Jiang, Wei; Zhu, Lianfeng; Yao, Youwei

2017-01-01

Amorphous indium gallium zinc oxide (a-IGZO) powder was prepared by typical solution-based process and post-annealing process. The sample was used as sensor for detecting C2H5OH, H2, and CO. Gas-sensing performance was found to be highly sensitive to C2H5OH gas in a wide range of concentration (0.5–1250 ppm) with the response of 2.0 towards 0.5 ppm and 89.2 towards 1250 ppm. Obvious difference of response towards C2H5OH, H2, and CO was found that the response e.g., was 33.20, 6.64, and 2.84 respectively at the concentration of 200 ppm. The response time and recovery time of was 32 s and 14 s respectively towards 200 ppm concentration of C2H5OH gas under heating voltage of 6.5 V. PMID:28538686

Tailored Algorithm for Sensitivity Enhancement of Gas Concentration Sensors Based on Tunable Laser Absorption Spectroscopy.

PubMed

Vargas-Rodriguez, Everardo; Guzman-Chavez, Ana Dinora; Baeza-Serrato, Roberto

2018-06-04

In this work, a novel tailored algorithm to enhance the overall sensitivity of gas concentration sensors based on the Direct Absorption Tunable Laser Absorption Spectroscopy (DA-ATLAS) method is presented. By using this algorithm, the sensor sensitivity can be custom-designed to be quasi constant over a much larger dynamic range compared with that obtained by typical methods based on a single statistics feature of the sensor signal output (peak amplitude, area under the curve, mean or RMS). Additionally, it is shown that with our algorithm, an optimal function can be tailored to get a quasi linear relationship between the concentration and some specific statistics features over a wider dynamic range. In order to test the viability of our algorithm, a basic C 2 H 2 sensor based on DA-ATLAS was implemented, and its experimental measurements support the simulated results provided by our algorithm.

Rhythm Analyses Of Melodies Used To Obtain Women Marathon Gold Medal

NASA Astrophysics Data System (ADS)

Tacano, Munecazu; Yokokura, Saburo; Kajiwara, Yoko; Pavelka, Jan; Tanuma, Nobuhisa; Uemura, Tatsuhisa; Hashiguchi, Sumihisa; Sikula, Josef

2005-11-01

In Athena Olympics in 2004 a Japanese girl got the gold medal in Women Marathon games. Just before the beginning, she was listening to some domestic melodies in order to concentrate on the race. The rhythm or power of that music is found to have the typical 1/f noise characteristics. The 1/f music is found effective to concentrate as well as to relax themselves for a fairly long time range, while some short time trial runner uses a kind of white noise like music.

A Theoretical Basis for the Transition to Denitrification at Nanomolar Oxygen Concentrations

NASA Astrophysics Data System (ADS)

Zakem, E.; Follows, M. J.

2016-02-01

Current climate change is likely to expand the size and intensity of marine oxygen minimum zones. How will this affect denitrification rates? Current global biogeochemical models typically prescribe a critical oxygen concentration below which anaerobic activity occurs, rather than resolve the underlying microbial processes. Here, we explore the dynamics of an idealized, simulated anoxic zone in which multiple prokaryotic metabolisms are resolved mechanistically, defined by redox chemistry and biophysical constraints. We first ask, what controls the critical oxygen concentration governing the favorability of aerobic or anaerobic respiration? The predicted threshold oxygen concentration varies as a function of the environment as well as of cell physiology, and lies within the nanomolar range. The model thus provides a theoretical underpinning for the recent observations of nanomolar oxygen concentrations in oxygen minimum zones. In the context of an idealized, two-dimensional intensified upwelling simulation, we also predict denitrification at oxygen concentrations orders of magnitude higher due to physical mixing, reconciling observations of denitrification over a similar range and demonstrating a decoupling of denitrification from the local oxygen concentration. In a sensitivity study with the idealized ocean model, we comment upon the relationship between the volume of anoxic waters and total denitrification.

Using in situ pore water concentrations to estimate the phytotoxicity of nicosulfuron in soils to corn (Zea mays L.).

PubMed

Liu, Kailin; Cao, Zhengya; Pan, Xiong; Yu, Yunlong

2012-08-01

The phytotoxicity of an herbicide in soil is typically dependent on the soil characteristics. To obtain a comparable value of the concentration that inhibits growth by 50% (IC50), 0.01 M CaCl(2) , excess pore water (EPW) and in situ pore water (IPW) were used to extract the bioavailable fraction of nicosulfuron from five different soils to estimate the nicosulfuron phytotoxicity to corn (Zea mays L.). The results indicated that the phytotoxicity of nicosulfuron in soils to corn depended on the soil type, and the IC50 values calculated based on the amended concentration of nicosulfuron ranged from 0.77 to 9.77 mg/kg among the five tested soils. The range of variation in IC50 values for nicosulfuron was smaller when the concentrations of nicosulfuron extracted with 0.01 M CaCl(2) and EPW were used instead of the amended concentration. No significant difference was observed among the IC50 values calculated from the IPW concentrations of nicosulfuron in the five tested soils, suggesting that the concentration of nicosulfuron in IPW could be used to estimate the phytotoxicity of residual nicosulfuron in soils. Copyright © 2012 SETAC.

Polycyclic aromatic hydrocarbons in surface sediment of typical estuaries and the spatial distribution in Haihe river basin.

PubMed

Liu, Jing L; Zhang, Jing; Liu, Feng; Zhang, Lu L

2014-05-01

Polycyclic aromatic hydrocarbons (PAHs) with carcinogenic and mutagenic characteristics have been detected in many estuaries and bays around the world. To detect the contaminated level in typical estuaries in Haihe river basin, China, a comprehensive survey of 16 PAHs in surface sediment has been conducted and an ecological risk assessment has been taken. It showed that Haihe river estuary had the highest concentration, ranging from 92.91 to 15886.00 ng g(-1). And Luan river estuary has the lowest polluted level, ranging from 39.55 to 328.10 ng g(-1). PAHs in sediment were dominated by low and mid molecular weight PAHs in all the sampling sites. Most of the sampling sites in all sampling seasons indicated a rarely happened ecological risk of ΣPAHs, while the S6 in Haihe river estuary was in an occasionally anticipated risk. To illustrate the spatial distribution pattern of PAHs in surface sediment in Haihe river basin, the results were compared with previous research of the research team. Based on data of the comparison, it had been revealed that Haihe river had the most serious PAHs pollution, with an average concentration of 5884.86 ng g(-1), and showed the highest contamination level in all four ecological units. The ΣPAHs concentration showed in a rank of reservoir > estuary > rural area > city.

Brief Exposure to Secondhand Smoke Reversibly Impairs Endothelial Vasodilatory Function

PubMed Central

2014-01-01

Introduction: We sought to determine the effects of brief exposures to low concentrations of tobacco secondhand smoke (SHS) on arterial flow-mediated dilation (FMD, a nitric oxide-dependent measure of vascular endothelial function), in a controlled animal model never before exposed to smoke. In humans, SHS exposure for 30min impairs FMD. It is important to gain a better understanding of the acute effects of exposure to SHS at low concentrations and for brief periods of time. Methods: We measured changes in FMD in rats exposed to a range of real-world levels of SHS for durations of 30min, 10min, 1min, and 4 breaths (roughly 15 s). Results: We observed a dose-response relationship between SHS particle concentration over 30min and post-exposure impairment of FMD, which was linear through the range typically encountered in smoky restaurants and then saturated at higher concentrations. One min of exposure to SHS at moderate concentrations was sufficient to impair FMD. Conclusions: Brief SHS exposure at real-world levels reversibly impairs FMD. Even 1min of SHS exposure can cause reduction of endothelial function. PMID:24302638

Low Imazapyr Concentrations in Streamflow From Forest Sites

Treesearch

J.L. Michael

1989-01-01

This study evaluated the fate of the herbicide, ARSENAL(R) from large, forest-land watersheds in typical soils of the southern United States. Imazapyr is active over a range of rates and is recommended at rates up to 1.68 kilograms acid equivalent per hectare (kg/ha) for the control of annual and perennial grasses, broadleaved weeds, and woody competition. The...

Laboratory measurements of selected optical, physical, chemical, and remote-sensing properties of five water mixtures containing Calvert clay and a nonfluorescing dye

NASA Technical Reports Server (NTRS)

Usry, J. W.; Whitlock, C. H.; Poole, L. R.; Witte, W. G., Jr.

1981-01-01

Total suspended solids concentrations ranged from 6.1 ppm to 24.3 ppm and sizes ranged between 1.5 micrometers and 10 micrometers with the most frequently occurring size less than 2 micrometers. Iron concentration was less than 1 percent of the total suspended solids. Nonfluorescing dye concentrations of the two mixtures were 20 ppm and 40 ppm. Attenuation coefficient for the five mixtures ranged from 4.8/m to 21.3/m. Variations in volume scattering function with phase angle were typical. Variations in attenuation and absorption coefficient with wavelength were similar for the mixtures without the dye. Attenuation coefficient of the mixtures with the dye increased for wavelengths less than 600 nm due to the dye's strong absorption peak near 500 nm. Reflectance increased as the concentration of Calvert clay increased and peaked near 600 nm. The nonfluorescent dye decreased the magnitude of the peak, but had practically no effect on the variation for wavelengths greater than 640 nm. At wavelengths less than 600 nm, the spectral variations of the mixtures with the dye were significantly different from those mixtures without the dye.

Measuring SO2 ship emissions with an ultra-violet imaging camera

NASA Astrophysics Data System (ADS)

Prata, A. J.

2013-11-01

Over the last few years fast-sampling ultra-violet (UV) imaging cameras have been developed for use in measuring SO2 emissions from industrial sources (e.g. power plants; typical fluxes ~1-10 kg s-1) and natural sources (e.g. volcanoes; typical fluxes ~10-100 kg s-1). Generally, measurements have been made from sources rich in SO2 with high concentrations and fluxes. In this work, for the first time, a UV camera has been used to measure the much lower concentrations and fluxes of SO2 (typical fluxes ~0.01-0.1 kg s-1) in the plumes from moving and stationary ships. Some innovations and trade-offs have been made so that estimates of the fluxes and path concentrations can be retrieved in real-time. Field experiments were conducted at Kongsfjord in Ny Ålesund, Svalbard, where emissions from cruise ships were made, and at the port of Rotterdam, Netherlands, measuring emissions from more than 10 different container and cargo ships. In all cases SO2 path concentrations could be estimated and fluxes determined by measuring ship plume speeds simultaneously using the camera, or by using surface wind speed data from an independent source. Accuracies were compromised in some cases because of the presence of particulates in some ship emissions and the restriction of single-filter UV imagery, a requirement for fast-sampling (>10 Hz) from a single camera. Typical accuracies ranged from 10-30% in path concentration and 10-40% in flux estimation. Despite the ease of use and ability to determine SO2 fluxes from the UV camera system, the limitation in accuracy and precision suggest that the system may only be used under rather ideal circumstances and that currently the technology needs further development to serve as a method to monitor ship emissions for regulatory purposes.

Bacterial and fungal aerosol in indoor environment in Upper Silesia, Poland

NASA Astrophysics Data System (ADS)

Pastuszka, Jozef S.; Kyaw Tha Paw, U.; Lis, Danuta O.; Wlazło, Agnieszka; Ulfig, Krzysztof

The purpose of this study was to find the typical concentration levels of bacterial and fungal bioaerosol in healthy and moldy homes as well as in office rooms in Upper Silesia Industrial Zone. Airborne bacteria and fungi were collected using the 6-stage Andersen impactor inside and outside of buildings. It was found that the typical level of bacterial aerosol indoors is about 10 3 CFU m -3 in homes and 10 2 CFU m -3 in offices. Only Micrococcus spp was present in all homes studied, constituting 36% of the bacterial genera. The second most common was Staphylococcus epidermidis, present in 76% of homes and constituting 14% of the total. The concentration of fungal aerosol in winter ranged from 10 to 10 2 CFU m -3 in healthy homes and from 10 to 10 3 CFU m -3 in homes with mold problems. In summer these values were elevated reaching 10 3 CFU m -3 in healthy homes and 10 3-10 4 CFU m -3 in moldy buildings. In healthy homes the relative concentration of observed species, including Penicillium, ranged from 3 to about 50% while in moldy homes the highest concentration of Penicillium accounted for 90% of the total fungi. However, the differences between viable fungal species as well as concentrations observed in moldy and healthy homes seem to be too small to be a reason of significantly higher risk for allergic asthma symptoms in any group of buildings. Comparison of the respirable fraction of airborne bacteria and fungi with literature data suggests that the percentage of respirable fungi and bacteria is generally not dependent on the type of home, building material, geographical factors and particulate air pollution.

Mitigation of nitrous oxide (N2O) emissions from denitrifying fluidized bed bioreactors (DFBBRs) using calcium.

PubMed

Eldyasti, Ahmed; Nakhla, George; Zhu, Jesse

2014-12-01

Nitrous oxide (N2O) is a significant anthropogenic greenhouse gases (AnGHGs) emitted from biological nutrient removal (BNR) processes. In this study, N2O production from denitrifying fluidized bed bioreactors (DFBBR) was reduced using calcium (Ca2+) dosage. The DFBBRs were operated on a synthetic municipal wastewater at four different calcium concentrations ranging from the typical municipal wastewater Ca2+ concentration (60 mg Ca2+/L) to 240 mg Ca2+/L at two different COD/N ratios. N2O emission rates, extracellular polymeric substances (EPS), water quality parameters, and microscopic images were monitored regularly in both phases. Calcium concentrations played a significant role in biofilm morphology with the detachment rates for R120Ca, R180Ca, and R240Ca 75% lower than for R60Ca, respectively. The N2O conversion rate at the typical municipal wastewater Ca2+ concentration (R60Ca) was about 0.53% of the influent nitrogen loading as compared with 0.34%, 0.42%, and 0.41% for R120Ca, R180Ca, and R240Ca, respectively corresponding to 21-36% reduction. Copyright © 2014 Elsevier Ltd. All rights reserved.

Pollutant exposures from natural gas cooking burners: a simulation-based assessment for Southern California.

PubMed

Logue, Jennifer M; Klepeis, Neil E; Lobscheid, Agnes B; Singer, Brett C

2014-01-01

Residential natural gas cooking burners (NGCBs) can emit substantial quantities of pollutants, and they are typically used without venting range hoods. We quantified pollutant concentrations and occupant exposures resulting from NGCB use in California homes. A mass-balance model was applied to estimate time-dependent pollutant concentrations throughout homes in Southern California and the exposure concentrations experienced by individual occupants. We estimated nitrogen dioxide (NO2), carbon monoxide (CO), and formaldehyde (HCHO) concentrations for 1 week each in summer and winter for a representative sample of Southern California homes. The model simulated pollutant emissions from NGCBs as well as NO2 and CO entry from outdoors, dilution throughout the home, and removal by ventilation and deposition. Residence characteristics and outdoor concentrations of NO2 and CO were obtained from available databases. We inferred ventilation rates, occupancy patterns, and burner use from household characteristics. We also explored proximity to the burner(s) and the benefits of using venting range hoods. Replicate model executions using independently generated sets of stochastic variable values yielded estimated pollutant concentration distributions with geometric means varying by <10%. The simulation model estimated that-in homes using NGCBs without coincident use of venting range hoods-62%, 9%, and 53% of occupants are routinely exposed to NO2, CO, and HCHO levels that exceed acute health-based standards and guidelines. NGCB use increased the sample median of the highest simulated 1-hr indoor concentrations by 100, 3,000, and 20 ppb for NO2, CO, and HCHO, respectively. Reducing pollutant exposures from NGCBs should be a public health priority. Simulation results suggest that regular use of even moderately effective venting range hoods would dramatically reduce the percentage of homes in which concentrations exceed health-based standards.

Sedimentation and occurrence and trends of selected chemical constituents in bottom sediment of 10 small reservoirs, Eastern Kansas

USGS Publications Warehouse

Juracek, Kyle E.

2004-01-01

Many municipalities in Kansas rely on small reservoirs as a source of drinking water and for recreational activities. Because of their significance to the community, management of the reservoirs and the associated basins is important to protect the reservoirs from degradation. Effective reservoir management requires information about water quality, sedimentation, and sediment quality. A combination of bathymetric surveying and bottom-sediment coring during 2002 and 2003 was used to investigate sediment deposition and the occurrence of selected nutrients (total nitrogen and total phosphorus), organic and total carbon, 26 trace elements, 15 organochlorine compounds, and 1 radionuclide in the bottom sediment of 10 small reservoirs in eastern Kansas. Original reservoir water-storage capacities ranged from 23 to 5,845 acre-feet. The mostly agricultural reservoir basins range in area from 0.6 to 14 square miles. The mean annual net volume of deposited sediment, estimated separately for several of the reservoirs, ranged from about 43,600 to about 531,000 cubic feet. The estimated mean annual net mass of deposited sediment ranged from about 1,360,000 to about 23,300,000 pounds. The estimated mean annual net sediment yields from the reservoir basins ranged from about 964,000 to about 2,710,000 pounds per square mile. Compared to sediment yield estimates provided by a statewide study published in 1965, the estimates determined in this study differed substantially and were typically smaller. A statistically significant positive correlation was determined for the relation between sediment yield and mean annual precipitation. Nutrient concentrations in the bottom sediment varied substantially among the 10 reservoirs. Median total nitrogen concentrations ranged from 1,400 to 3,700 milligrams per kilogram. Median total phosphorus concentrations ranged from 550 to 1,300 milligrams per kilogram. A statistically significant positive trend (that is, nutrient concentration increased toward the top of the sediment core) was indicated in one reservoir for total nitrogen and in two reservoirs for total phosphorus. Also, a possible positive trend for total nitrogen was indicated in two other reservoirs. These trends in nutrient concentrations may be related to a statewide increase in fertilizer use. Alternatively, the trends may be indicative of diagenesis (that is, postdepositional changes in the sediment caused by various processes including decomposition). Nutrient loads and yields also varied substantially among the five reservoirs for which loads and yields were estimated. Estimated mean annual net loads of total nitrogen deposited in the bottom sediment ranged from 4,080 to 49,100 pounds. Estimated mean annual net loads of total phosphorus deposited in the bottom sediment ranged from 1,120 to 20,800 pounds. Estimated mean annual net yields of total nitrogen from the basins ranged from 2,210 to 6,800 pounds per square mile. Estimated mean annual net yields of total phosphorus from the basins ranged from 598 to 2,420 pounds per square mile. Compared to nonenforceable sediment-quality guidelines adopted by the U.S. Environmental Protection Agency, bottom-sediment concentrations of arsenic, chromium, copper, and nickel in samples from all 10 reservoirs typically exceeded the threshold-effects levels (TELs) but were less than the probable-effects levels (PELs). TELs represent the concentrations above which toxic biological effects occasionally occur in aquatic organisms, whereas PELs represent the concentrations above which toxic biological effects usually or frequently occur. Concentrations of cadmium, lead, and zinc exceeded the TELs but were less than the PELs in sediment samples from about one-half of the reservoirs and were less than the TELs in samples from the remaining reservoirs. Mercury concentrations were less than the TEL (information only available for four reservoirs). Silver was not detected in the bottom sediment fro

A modified impulse-response representation of the global near-surface air temperature and atmospheric concentration response to carbon dioxide emissions

NASA Astrophysics Data System (ADS)

Millar, Richard J.; Nicholls, Zebedee R.; Friedlingstein, Pierre; Allen, Myles R.

2017-06-01

Projections of the response to anthropogenic emission scenarios, evaluation of some greenhouse gas metrics, and estimates of the social cost of carbon often require a simple model that links emissions of carbon dioxide (CO2) to atmospheric concentrations and global temperature changes. An essential requirement of such a model is to reproduce typical global surface temperature and atmospheric CO2 responses displayed by more complex Earth system models (ESMs) under a range of emission scenarios, as well as an ability to sample the range of ESM response in a transparent, accessible and reproducible form. Here we adapt the simple model of the Intergovernmental Panel on Climate Change 5th Assessment Report (IPCC AR5) to explicitly represent the state dependence of the CO2 airborne fraction. Our adapted model (FAIR) reproduces the range of behaviour shown in full and intermediate complexity ESMs under several idealised carbon pulse and exponential concentration increase experiments. We find that the inclusion of a linear increase in 100-year integrated airborne fraction with cumulative carbon uptake and global temperature change substantially improves the representation of the response of the climate system to CO2 on a range of timescales and under a range of experimental designs.

Characteristics of cabin air quality in school buses in Central Texas

NASA Astrophysics Data System (ADS)

Rim, Donghyun; Siegel, Jeffrey; Spinhirne, Jarett; Webb, Alba; McDonald-Buller, Elena

This study assessed in-cabin concentrations of diesel-associated air pollutants in six school buses with diesel engines during a typical route in suburban Austin, Texas. Air exchange rates measured by SF 6 decay were 2.60-4.55 h -1. In-cabin concentrations of all pollutants measured exhibited substantial variability across the range of tests even between buses of similar age, mileage, and engine type. In-cabin NO x concentrations ranged from 44.7 to 148 ppb and were 1.3-10 times higher than roadway NO x concentrations. Mean in-cabin PM 2.5 concentrations were 7-20 μg m -3 and were generally lower than roadway levels. In-cabin concentrations exhibited higher variability during cruising mode than frequent stops. Mean in-cabin ultrafine PM number concentrations were 6100-32,000 particles cm -3 and were generally lower than roadway levels. Comparison of median concentrations indicated that in-cabin ultrafine PM number concentrations were higher than or approximately the same as the roadway concentrations, which implied that, by excluding the bias caused by local traffic, ultrafine PM levels were higher in the bus cabin than outside of the bus. Cabin pollutant concentrations on three buses were measured prior to and following the phased installation of a Donaldson Spiracle Crankcase Filtration System and a Diesel Oxidation Catalyst. Following installation of the Spiracle, the Diesel Oxidation Catalyst provided negligible or small additional reductions of in-cabin pollutant levels. In-cabin concentration decreases with the Spiracle alone ranged from 24 to 37% for NO x and 26 to 62% and 6.6 to 43% for PM 2.5 and ultrafine PM, respectively. Comparison of the ranges of PM 2.5 and ultrafine PM variations between repetitive tests suggested that retrofit installation could not always be conclusively linked to the decrease of pollutant levels in the bus cabin.

Water requirements of the iron and steel industry

USGS Publications Warehouse

Walling, Faulkner B.; Otts, Louis Ethelbert

1967-01-01

Twenty-nine steel plants surveyed during 1957 and 1958 withdrew from various sources about 1,400 billion gallons of water annually and produced 40.8 million tons of ingot steel. This is equivalent to about 34,000 gallons of water per ton of steel. Fifteen iron ore mines and fifteen ore concentration plants together withdrew annually about 89,000 million gallons to produce 15 million tons of iron ore concentrate, or 5,900 gallons per ton of concentrate. About 97 percent of the water used in the steel plants came from surface sources, 2.2 percent was reclaimed sewage, and 1.2 percent was ground water. Steel plants supplied about 96 percent of their own water requirements, although only three plants used self-supplied water exclusively. Water used by the iron ore mines and concentration plants was also predominantly self supplied from surface source. Water use in the iron and steel industry varied widely and depended on the availability of water, age and condition of plants and equipment, kinds of processes, and plant operating procedures. Gross water use in integrated steel plants ranged from 11,200 to 110,000 gallons per ton of steel ingots, and in steel processing plants it ranged from 4,180 to 26,700 gallons per ton. Water reuse also varied widely from 0 to 18 times in integrated steel plants and from 0 to 44 times in steel processing plants. Availability of water seemed to be the principal factor in determining the rate of reuse. Of the units within steel plants, a typical (median) blast furnace required 20,500 gallons of water per ton of pig iron. At the 1956-60 average rate of pig iron consumption, this amounts to about 13,000 gallons per ton of steel ingots or about 40 percent of that required by a typical integrated steel plant 33,200 gallons per ton. Different processes of iron ore concentration are devised specifically for the various kinds of ore. These processes result in a wide range of water use from 124 to 11,300 gallons of water per ton of iron ore concentrate. Water use in concentration plants is related to the physical state of the ore. The data in this report indicate that grain size of the ore is the most important factor; the very fine grained taconite and jasper required the greatest amount of water. Reuse was not widely practiced in the iron ore industry.Consumption of water by integrated steel plants ranged from 0 to 2,010 gallons per ton of ingot steel and by steel processing plants from 120 to 3,420 gallons per ton. Consumption by a typical integrated steel plant was 681 gallons per ton of ingot steel, about 1.8 percent of the intake and about 1 percent of the gross water use. Consumption by a typical steel processing plant was 646 gallons per ton, 18 percent of the intake, and 3.2 percent of the gross water use. The quality of available water was found not to be a critical factor in choosing the location of steel plants, although changes in equipment and in operating procedures are necessary when poor-quality water is used. The use of saline water having a concentration of dissolved solids as much as 10,400 ppm (parts per million) was reported. This very saline water was used for cooling furnaces and for quenching slag. In operations such as rolling steel in which the water comes into contact with the steel being processed, better quality water is used, although water containing as much as 3,410 ppm dissolved solids has been used for this purpose. Treatment of water for use in the iron and steel industry was not widely practiced. Disinfection and treatment for scale and corrosion control were the most frequently used treatment methods.

Comparison of three point-of-care blood glucose meters for use in adult and juvenile alpacas.

PubMed

Tennent-Brown, Brett S; Koenig, Amie; Williamson, Lisa H; Boston, Raymond C

2011-08-01

To compare the performance of 3 point-of-care glucose meters in adult and juvenile alpacas with that of a laboratory-based analyzer. Evaluation study. 35 adult alpacas and 21 juvenile alpacas. Whole blood samples obtained via jugular venipuncture were tested with all 3 point-of-care glucose meters; plasma samples were also tested with 1 of those meters. Glucose concentrations determined by use of the point-of-care meters were compared with results from the laboratory-based analyzer. Plasma glucose concentrations determined by use of the laboratory-based analyzer ranged from 36 to 693 mg/dL. Over the entire range of glucose concentrations tested, the Lin concordance correlation coefficient (agreement) was significant and excellent for all comparisons. Concordance decreased for 1 glucometer when testing whole blood samples over a narrower range of glucose concentrations (50 to 200 mg/dL). Bias was typically small (< 10 mg/dL) for 3 of the 4 comparisons but considerable for 1 meter with the use of whole blood. The limits of agreement were wide for all comparisons over the entire range of glucose concentrations tested but decreased to within acceptable limits when the narrower glucose range (50 to 200 mg/dL) was analyzed for 3 of the comparisons. For samples with a PCV < 25%, bias and the limits of agreement were greater for one of the meters tested. Discrepancies between point-of-care glucose meters and reference techniques can be considerable in alpacas, emphasizing the importance of assessing individual meter performance in a target population.

Searching trans-resveratrol in fruits and vegetables: a preliminary screening.

PubMed

Sebastià, Natividad; Montoro, Alegría; León, Zacarías; Soriano, Jose M

2017-03-01

Resveratrol is a phytoalexin with potent anti-inflammatory, anti-oxidant and anti-carcinogenic effects. The object of this work was to determine whether this promising compound was present in the typical fruits and vegetables used in the Mediterranean diet. Our results indicated the presence of trans -resveratrol in concentrations ranging from 0.2 µg/g in tomatoes and 3 lg/g. in strawberries.

Identifying pathways and processes affecting nitrate and orthophosphate inputs to streams in agricultural watersheds

USGS Publications Warehouse

Tesoriero, A.J.; Duff, J.H.; Wolock, D.M.; Spahr, N.E.; Almendinger, J.E.

2009-01-01

Understanding nutrient pathways to streams will improve nutrient management strategies and estimates of the time lag between when changes in land use practices occur and when water quality effects that result from these changes are observed. Nitrate and orthophosphate (OP) concentrations in several environmental compartments were examined in watersheds having a range of base flow index (BFI) values across the continental United States to determine the dominant pathways for water and nutrient inputs to streams. Estimates of the proportion of stream nitrate that was derived from groundwater increased as BFI increased. Nitrate concentration gradients between groundwater and surface water further supported the groundwater source of nitrate in these high BFI streams. However, nitrate concentrations in stream-bed pore water in all settings were typically lower than stream or upland groundwater concentrations, suggesting that nitrate discharge to streams was not uniform through the bed. Rather, preferential pathways (e.g., springs, seeps) may allow high nitrate groundwater to bypass sites of high biogeochemical transformation. Rapid pathway compartments (e.g., overland flow, tile drains) had OP concentrations that were typically higher than in streams and were important OP conveyers in most of these watersheds. In contrast to nitrate, the proportion of stream OP that is derived from ground water did not systematically increase as BFI increased. While typically not the dominant source of OP, groundwater discharge was an important pathway of OP transport to streams when BFI values were very high and when geochemical conditions favored OP mobility in groundwater. Copyright ?? 2009 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

On the competition among aerosol number, size and composition in predicting CCN variability: a multi-annual field study in an urbanized desert.

PubMed

Crosbie, E; Youn, J-S; Balch, B; Wonaschütz, A; Shingler, T; Wang, Z; Conant, W C; Betterton, E A; Sorooshian, A

2015-02-10

A 2-year data set of measured CCN (cloud condensation nuclei) concentrations at 0.2 % supersaturation is combined with aerosol size distribution and aerosol composition data to probe the effects of aerosol number concentrations, size distribution and composition on CCN patterns. Data were collected over a period of 2 years (2012-2014) in central Tucson, Arizona: a significant urban area surrounded by a sparsely populated desert. Average CCN concentrations are typically lowest in spring (233 cm -3 ), highest in winter (430 cm -3 ) and have a secondary peak during the North American monsoon season (July to September; 372 cm -3 ). There is significant variability outside of seasonal patterns, with extreme concentrations (1 and 99 % levels) ranging from 56 to 1945 cm -3 as measured during the winter, the season with highest variability. Modeled CCN concentrations based on fixed chemical composition achieve better closure in winter, with size and number alone able to predict 82% of the variance in CCN concentration. Changes in aerosol chemical composition are typically aligned with changes in size and aerosol number, such that hygroscopicity can be parameterized even though it is still variable. In summer, models based on fixed chemical composition explain at best only 41% (pre-monsoon) and 36% (monsoon) of the variance. This is attributed to the effects of secondary organic aerosol (SOA) production, the competition between new particle formation and condensational growth, the complex interaction of meteorology, regional and local emissions and multi-phase chemistry during the North American monsoon. Chemical composition is found to be an important factor for improving predictability in spring and on longer timescales in winter. Parameterized models typically exhibit improved predictive skill when there are strong relationships between CCN concentrations and the prevailing meteorology and dominant aerosol physicochemical processes, suggesting that similar findings could be possible in other locations with comparable climates and geography.

Understanding the Viscosity of Liquids used in Infant Dysphagia Management

PubMed Central

Frazier, Jackie; Chestnut, Amanda; Jackson, Arwen; Barbon, Carly E. A.; Steele, Catriona M.; Pickler, Laura

2016-01-01

When assessing swallowing in infants, it is critical to have confidence that the liquids presented during the swallow study closely replicate the viscosity of liquids in the infant's typical diet. However, we lack research on rheological properties of frequently used infant formulas or breastmilk, and various forms of barium contrast media used in swallow studies. The aim of the current study was to provide objective viscosity measurements for typical infant liquid diet options and barium contrast media. A TA-Instruments AR2000 Advanced Rheometer was used to measure the viscosity, five standard infant formulas, three barium products and two breastmilk samples. Additionally, this study measured the viscosity of infant formulas and breastmilk when mixed with powdered barium contrast in a 20% weight-to-volume (w/v) concentration. Study findings determined that standard infant formulas and the two breastmilk samples had low viscosities, at the lower end of the National Dysphagia Diet (NDD) thin liquid range. Two specialty formulas tested had much thicker viscosities, close to the NDD nectar-thick liquid range lower boundary. The study showed differences in viscosity between two 60% w/v barium products (Liquid E-Z-Paque® and E-Z-Paque® powder); the powdered product had a much lower viscosity, despite identical barium concentration. When E-Z-Paque® powdered barium was mixed in a 20% w/v concentration using water, standard infant formulas or breastmilk, the resulting viscosities were at the lower end of the NDD thin range, and only slightly thicker than the non-barium comparator liquids. When E-Z-Paque® powdered barium was mixed in a 20% w/v concentration with the two thicker specialty formulas (Enfamil AR 20kcal and 24 kcal), unexpected alterations in their original viscosity occurred. These findings highlight the clinical importance of objective measures of viscosity as well as objective data on how infant formulas or breastmilk may change in consistency when mixed with barium. PMID:27412005

Understanding the Viscosity of Liquids used in Infant Dysphagia Management.

PubMed

Frazier, Jacqueline; Chestnut, Amanda H; Jackson, Arwen; Barbon, Carly E A; Steele, Catriona M; Pickler, Laura

2016-10-01

When assessing swallowing in infants, it is critical to have confidence that the liquids presented during the swallow study closely replicate the viscosity of liquids in the infant's typical diet. However, we lack research on rheological properties of frequently used infant formulas or breastmilk, and various forms of barium contrast media used in swallow studies. The aim of the current study was to provide objective viscosity measurements for typical infant liquid diet options and barium contrast media. A TA-Instruments AR2000 Advanced Rheometer was used to measure the viscosity of five standard infant formulas, three barium products, and two breastmilk samples. Additionally, this study measured the viscosity of infant formulas and breastmilk when mixed with powdered barium contrast in a 20 % weight-to-volume (w/v) concentration. The study findings determined that standard infant formulas and the two breastmilk samples had low viscosities, at the lower end of the National Dysphagia Diet (NDD) thin liquid range. Two specialty formulas tested had much thicker viscosities, close to the lower boundary of the NDD nectar-thick liquid range. The study showed differences in viscosity between 60 % w/v barium products (Liquid E-Z-Paque(®) and E-Z-Paque(®) powder); the powdered product had a much lower viscosity, despite identical barium concentration. When E-Z-Paque(®) powdered barium was mixed in a 20 % w/v concentration using water, standard infant formulas, or breastmilk, the resulting viscosities were at the lower end of the NDD thin range and only slightly thicker than the non-barium comparator liquids. When E-Z-Paque(®) powdered barium was mixed in a 20 % w/v concentration with the two thicker specialty formulas (Enfamil AR 20 and 24 kcal), unexpected alterations in their original viscosity occurred. These findings highlight the clinical importance of objective measures of viscosity as well as objective data on how infant formulas or breastmilk may change in consistency when mixed with barium.

Fuel mixture stratification as a method for improving homogeneous charge compression ignition engine operation

DOEpatents

Dec, John E [Livermore, CA; Sjoberg, Carl-Magnus G [Livermore, CA

2006-10-31

A method for slowing the heat-release rate in homogeneous charge compression ignition ("HCCI") engines that allows operation without excessive knock at higher engine loads than are possible with conventional HCCI. This method comprises injecting a fuel charge in a manner that creates a stratified fuel charge in the engine cylinder to provide a range of fuel concentrations in the in-cylinder gases (typically with enough oxygen for complete combustion) using a fuel with two-stage ignition fuel having appropriate cool-flame chemistry so that regions of different fuel concentrations autoignite sequentially.

Isotopically modified silver nanoparticles to assess nanosilver bioavailability and toxicity at environmentally relevant exposures

USGS Publications Warehouse

Croteau, Marie-Noële; Dybowska, Agnieszka D.; Luoma, Samuel N.; Misra, Superb K.; Valsami-Jones, Eugenia

2014-01-01

A major challenge in understanding the environmental implications of nanotechnology lies in studying nanoparticle uptake in organisms at environmentally realistic exposure concentrations. Typically, high exposure concentrations are needed to trigger measurable effects and to detect accumulation above background. But application of tracer techniques can overcome these limitations. Here we synthesised, for the first time, citrate-coated Ag nanoparticles using Ag that was 99.7 % 109Ag. In addition to conducting reactivity and dissolution studies, we assessed the bioavailability and toxicity of these isotopically modified Ag nanoparticles (109Ag NPs) to a freshwater snail under conditions typical of nature. We showed that accumulation of 109Ag from 109Ag NPs is detectable in the tissues of Lymnaea stagnalis after 24-h exposure to aqueous concentrations as low as 6 ng L–1 as well as after 3 h of dietary exposure to concentrations as low as 0.07 μg g–1. Silver uptake from unlabelled Ag NPs would not have been detected under similar exposure conditions. Uptake rates of 109Ag from 109Ag NPs mixed with food or dispersed in water were largely linear over a wide range of concentrations. Particle dissolution was most important at low waterborne concentrations. We estimated that 70 % of the bioaccumulated 109Ag concentration in L. stagnalis at exposures –1 originated from the newly solubilised Ag. Above this concentration, we predicted that 80 % of the bioaccumulated 109Ag concentration originated from the 109Ag NPs. It was not clear if agglomeration had a major influence on uptake rates.

Contamination of Phthalate Esters (PAEs) in Typical Wastewater-Irrigated Agricultural Soils in Hebei, North China.

PubMed

Zhang, Yuan; Liang, Qiong; Gao, Rutai; Hou, Haobo; Tan, Wenbing; He, Xiaosong; Zhang, Hui; Yu, Minda; Ma, Lina; Xi, Beidou; Wang, Xiaowei

2015-01-01

The Wangyang River (WYR) basin is a typical wastewater irrigation area in Hebei Province, North China. This study investigated the concentration and distribution of six priority phthalate esters (PAEs) in the agricultural soils in this area. Thirty-nine soil samples (0-20 cm) were collected along the WYR to assess the PAE residues in soils. Results showed that PAEs are ubiquitous environmental contaminants in the topsoil obtained from the irrigation area. The concentrations of Σ6PAEs range from 0.191 μg g-1 dw to 0.457 μg g-1 dw with an average value of 0.294 μg g-1 dw. Di(2-ethylhexyl) phthalate (DEHP) and di-n-butyl phthalate (DnBP) are the dominant PAE species in the agricultural soils. Among the DEHP concentrations, the highest DEHP concentration was found at the sites close to the villages; this result suggested that dense anthropogenic activities and random garbage disposal in the rural area are possible sources of PAEs. The PAE concentrations were weakly and positively correlated with soil organic carbon and soil enzyme activities; thus, these factors can affect the distribution of PAEs. This study further showed that only dimethyl phthalate (DMP) concentrations exceeded the recommended allowable concentrations; no remediation measures are necessary to control the PAEs in the WYR area. However, the PAEs in the topsoil may pose a potential risk to the ecosystem and human health in this area. Therefore, the exacerbating PAE pollution should be addressed.

Contamination of Phthalate Esters (PAEs) in Typical Wastewater-Irrigated Agricultural Soils in Hebei, North China

PubMed Central

Zhang, Yuan; Liang, Qiong; Gao, Rutai; Hou, Haobo; Tan, Wenbing; He, Xiaosong; Zhang, Hui; Yu, Minda; Ma, Lina; Xi, Beidou; Wang, Xiaowei

2015-01-01

The Wangyang River (WYR) basin is a typical wastewater irrigation area in Hebei Province, North China. This study investigated the concentration and distribution of six priority phthalate esters (PAEs) in the agricultural soils in this area. Thirty-nine soil samples (0–20 cm) were collected along the WYR to assess the PAE residues in soils. Results showed that PAEs are ubiquitous environmental contaminants in the topsoil obtained from the irrigation area. The concentrations of Σ6PAEs range from 0.191 μg g−1 dw to 0.457 μg g−1 dw with an average value of 0.294 μg g−1 dw. Di(2-ethylhexyl) phthalate (DEHP) and di-n-butyl phthalate (DnBP) are the dominant PAE species in the agricultural soils. Among the DEHP concentrations, the highest DEHP concentration was found at the sites close to the villages; this result suggested that dense anthropogenic activities and random garbage disposal in the rural area are possible sources of PAEs. The PAE concentrations were weakly and positively correlated with soil organic carbon and soil enzyme activities; thus, these factors can affect the distribution of PAEs. This study further showed that only dimethyl phthalate (DMP) concentrations exceeded the recommended allowable concentrations; no remediation measures are necessary to control the PAEs in the WYR area. However, the PAEs in the topsoil may pose a potential risk to the ecosystem and human health in this area. Therefore, the exacerbating PAE pollution should be addressed. PMID:26360905

On the Utility of the Molecular Oxygen Dayglow Emissions as Proxies for Middle Atmospheric Ozone

NASA Technical Reports Server (NTRS)

Mlynczak, Martin G.; Olander, Daphne S.

1995-01-01

Molecular oxygen dayglow emissions arise in part from processes related to the Hartley band photolysis of ozone. It is therefore possible to derive daytime ozone concentrations from measurements of the volume emission rate of either dayglow. The accuracy to which the ozone concentration can be inferred depends on the accuracy to which numerous kinetic and spectroscopic rate constants are known, including rates which describe the excitation of molecular oxygen by processes that are not related to the ozone concentration. We find that several key rate constants must be known to better than 7 percent accuracy in order to achieve an inferred ozone concentration accurate to 15 percent from measurements of either dayglow. Currently, accuracies for various parameters typically range from 5 to 100 percent.

Sulfur isotope and porewater geochemistry of Florida escarpment seep sediments

USGS Publications Warehouse

Chanton, J.P.; Martens, C.S.; Paull, C.K.; Coston, J.A.

1993-01-01

Distributions of porewater constituents, SO4=, NH4+, Cl-, ???CO2, and H2S, solid phase iron, and sulfur concentrations, and the sulfur isotopic composition of dissolved and solid phases were investigated in sediments from abyssal seeps at the base of the Florida escarpment. Despite the apparent similarity of seep sediment porewater chemistry to that of typical marine sediments undergoing early diagenesis, relationships between chemical distributions and isotopic measurements revealed that the distribution of pore fluid constituents was dominated by processes occurring within the platform rather than by in situ microbial processes. Ammonium and sulfate concentrations were linearly correlated with chloride concentrations, indicating that variations in porewater chemistry were controlled by the admixture of seawater and a sulfate depleted brine with a chlorinity of 27.5 ?? 1.9%. and 2.2 ?? 1.3 mM ammonium concentration. At sites dominated by seepage, dissolved sulfate isotopic composition remained near seawater values despite depletion in porewater concentrations. Porewater ???CO2 concentrations were found to be elevated relative to seawater, but not to the extent predicted from the observed sulfate depletion. Sediment solid phase sulfur was predominantly pyrite, at concentrations as high as 20% S by weight. In contrast to typical marine deposits, pyrite concentrations were not related to the quantity of sedimentary organic matter. Pyrite ??34S values ranged from -29%. to + 21%. (CDT). However, only positive ??34S values were observed at sites associated with high pyrite concentrations. Isotopically heavy pyrite was observed at sites with porewater sulfate of seawater-like isotopic composition. Isotopically light pyrite was associated with sites where porewater sulfate exhibited ??34S values greater than those in seawater, indicating the activity of in situ microbial sulfate reduction. Thus, dual sulfide sources are suggested to explain the range in sediment pyrite isotopic composition: a ??34S enriched (+10 to +20%.) source adverted from within the Florida platform, and a lighter 34S depleted component generated in situ from microbial reduction of seawater sulfate. The degree of pyritization of seep sediments was as high as 0.9 and was controlled by pyrite concentrations, which varied over a wider range than did the non-pyrite solid phase iron concentrations. The highest non-sulfide solid phase iron concentrations were observed in sediments that are believed to be at the "front" of the advancing seep fluids (i.e., hemipelagic sediments newly exposed to the seep fluids), indicating that dissolution of hemipelagic background sediment may be the source of at least half of the iron to the highly pyritized seep sediments. Porewater sulfide concentrations were variable, reaching a maximum of 5.7 mM, and were not correlated with the degree of pyritization of the sediments, suggesting that iron was not particularly limiting to pyrite formation. ?? 1993.

Modification of PBDEs (BDE-15, BDE-47, BDE-85 and BDE-126) biological toxicity, bio-concentration, persistence and atmospheric long-range transport potential based on the pharmacophore modeling assistant with the full factor experimental design.

PubMed

Jiang, Long; Li, Yu

2016-04-15

In this study, the properties of AhR binding affinity, bio-concentration factor, half-life and vapor pressure were selected as the typical indicators of biological toxicity, bio-concentration, persistence and atmospheric long-range transport potential for polybrominated diphenyl ethers (PBDEs), respectively. A three-dimensional pharmacophore modeling assistant with a full factor experimental design for each property was used to reveal the significant pharmacophore features and the substituent effects to obtain reasonable modified schemes for the selected target PBDEs. Finally, the performances of the persistent organic pollutant (POP) properties, the synthesis feasibility and the fire resistance of the modified compounds were evaluated. The most influential pharmacophore feature for all POP properties was the hydrophobic group, especially the vinyl and propyl groups. Modified compounds with two additional hydrophobic groups exhibited a better regulatory performance. The average reduction in the proportions of the four POP properties for the modified compounds (except for 3-phenyl-BDE-15) was 70.60%, 52.44%, 47.04% and 70.88%. In addition, the energy and the C-Br bond dissociation enthalpy of the four typical PBDEs were higher than those of the modified compounds (except for 3-phenyl-BDE-15), indicating the synthesis feasibility and the lower energy barrier of the modified compounds to release Br free radicals to provide fire resistance. Copyright © 2015 Elsevier B.V. All rights reserved.

External exposure doses due to gamma emitting natural radionuclides in some Egyptian building materials.

PubMed

Moharram, B M; Suliman, M N; Zahran, N F; Shennawy, S E; El Sayed, A R

2012-01-01

Using of building materials containing naturally occurring radionuclides as (238)U, (232)Th and (40)K and their progeny results in an external exposures of the housing of such buildings. In the present study, indoor dose rates for typical Egyptian rooms are calculated using the analytical method and activity concentrations of natural radionuclides in some building materials. Uniform chemical composition of the walls, floor and ceiling as well as uniform mass concentrations of the radionuclides in walls, floor and ceiling assumed. Different room models are assumed to discuss variation of indoor dose rates according to variation in room construction. Activity concentrations of (238)U, (232)Th and (40)K content in eight samples representative Clay soil and different building materials used in most recent Egyptian building were measured using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The specific activity for (238)U, (232)Th and (40)K, from the selected samples, were in the range 14.15-60.64, 2.75-84.66 and 7.35-554.4Bqkg(-1), respectively. The average indoor absorbed dose rates in air ranged from 0.005μGyh(-1) to 0.071μGyh(-1) and the corresponding population-weighted annual effective dose due to external gamma radiation varies from 0.025 to 0.345mSv. An outdoor dose rate for typical building samples in addition to some radiological hazards has been introduced for comparison. Copyright © 2011 Elsevier Ltd. All rights reserved.

Short-Time Glassy Dynamics in Viscous Protein Solutions with Competing Interactions

DOE PAGES

Godfrin, P. Douglas; Hudson, Steven; Hong, Kunlun; ...

2015-11-24

Although there have been numerous investigations of the glass transition for colloidal dispersions with only a short-ranged attraction, less is understood for systems interacting with a long-ranged repulsion in addition to this attraction, which is ubiquitous in aqueous protein solutions at low ionic strength. Highly puri ed concentrated lysozyme solutions are used as a model system and investigated over a large range of protein concentrations at very low ionic strength. Newtonian liquid behavior is observed at all concentrations, even up to 480 mg/mL, where the zero shear viscosity increases by more than three orders of magnitude with increasing concentration. Remarkably,more » despite this macroscopic liquid-like behavior, the measurements of the dynamics in the short-time limit shows features typical of glassy colloidal systems. Investigation of the inter-protein structure indicates that the reduced short-time mobility of the protein is caused by localized regions of high density within a heterogeneous density distribution. This structural heterogeneity occurs on intermediate range length scale, driven by the competing potential features, and is distinct from commonly studied colloidal gel systems in which a heterogeneous density distribution tends to extend to the whole system. The presence of long-ranged repulsion also allows for more mobility over large length and long time scales resulting in the macroscopic relaxation of the structure. The experimental results provide evidence for the need to explicitly include intermediate range order in theories for the macroscopic properties of protein solutions interacting via competing potential features.« less

Cascading and Parallelising Curvilinear Inertial Focusing Systems for High Volume, Wide Size Distribution, Separation and Concentration of Particles

PubMed Central

Miller, B.; Jimenez, M.; Bridle, H.

2016-01-01

Inertial focusing is a microfluidic based separation and concentration technology that has expanded rapidly in the last few years. Throughput is high compared to other microfluidic approaches although sample volumes have typically remained in the millilitre range. Here we present a strategy for achieving rapid high volume processing with stacked and cascaded inertial focusing systems, allowing for separation and concentration of particles with a large size range, demonstrated here from 30 μm–300 μm. The system is based on curved channels, in a novel toroidal configuration and a stack of 20 devices has been shown to operate at 1 L/min. Recirculation allows for efficient removal of large particles whereas a cascading strategy enables sequential removal of particles down to a final stage where the target particle size can be concentrated. The demonstration of curved stacked channels operating in a cascaded manner allows for high throughput applications, potentially replacing filtration in applications such as environmental monitoring, industrial cleaning processes, biomedical and bioprocessing and many more. PMID:27808244

Influence of Low-Level Prenatal Exposure to PCDD/Fs and PCBs on Empathizing, Systemizing and Autistic Traits: Results from the Duisburg Birth Cohort Study

PubMed Central

Nowack, Nikola; Wittsiepe, Jürgen; Kasper-Sonnenberg, Monika; Wilhelm, Michael; Schölmerich, Axel

2015-01-01

Background Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) are assumed to act as endocrine disruptor chemicals. Prenatal exposure to these pollutants might influence fetal steroid hormone levels, which are thought to be related to sex-typical development and autistic traits. Objectives We examined associations of prenatal levels of PCDD/Fs and PCBs with autism traits and sex-typical behaviour in childhood. Methods We measured levels of PCDD/Fs and PCBs in maternal blood samples during pregnancy using gas chromatography/high-resolution mass spectrometry. Sex-typical behaviour was assessed at 9 years of age (n = 96) and autistic traits at 10 years of age using the Social Responsiveness Scale (SRS; n = 100). Multiple regression analyses were conducted to estimate the associations between prenatal exposure and outcome variables. Results Blood concentrations (WHO2005-TEq) of ƩPCDD/Fs ranged from 2.93–46.45 pg/g lipid base (median = 12.91 pg/g lipid base) and concentrations of ƩPCBs were in the range of 1.24–25.47 pg/g lipid base (median = 6.85 pg/g lipid base) which is within the range of German background exposure. We found significant negative associations between PCDD/F levels in maternal blood and SRS scores in the whole group (β = -6.66, p < .05), in girls (β = -10.98, p < .05) and, in one SRS subscale, in boys (β = -6.86, p < .05). For PCB levels, associations with one SRS subscale were significant for the whole study group as were associations with two subscales in girls. We did not find significant associations between PCDD/F or PCB levels and sex-typical behaviour for either sex. Conclusions In an earlier part of this study, prenatal exposure to PCDD/Fs and PCBs was found to be associated with lower testosterone levels, therefore, our findings are consistent with the idea that autism spectrum conditions are related to fetal androgen levels. Several possible mechanisms, through which PCDD/Fs and PCBs might influence autistic behaviour, are discussed. PMID:26066795

ZnO Nanorod-Based Non-Enzymatic Optical Glucose Biosensor.

PubMed

Sarangi, Sachindra Nath; Nozaki, Shinji; Sahu, Surendra Nath

2015-06-01

The highly sensitive, interference-free and non-enzymatic optical sensing of glucose has been made possible for the first time using the hydrothermally synthesized ZnO nanorods. The UV irradiation of glucose-treated ZnO nanorods decomposes glucose into hydrogen peroxide (H2O2) and gluconic acid by UV oxidation. The ZnO nanorods play the role of a catalyst similar to the oxidase used in the enzymatic glucose sensors. The photoluminescence (PL) intensity of the near-band edge emission of the ZnO nanorods linearly decreased with the increased concentration of H2O2. Therefore, the glucose concentration is monitored over the wide range of 0.5-30 mM, corresponding to 9-540 mg/dL. The concentration range of the linear region in the calibration curve is suitable for its clinical use as a glucose sensor, because the glucose concentration of human serum is typically in the range of 80-120 mg/dL. In addition, the optical glucose sensor made of the ZnO nanorods is free from interference by bovin serum albumin, ascorbic acid or uric acid, which are also present in human blood. The non-enzymatic ZnO-nanorod sensor has been demonstrated with human serum samples from both normal persons and diabetic patients. There is a good agreement between the glucose concentrations measured by the PL quenching and standard clinical methods.

The assessment of bore-hole water quality of Kakamega County, Kenya

NASA Astrophysics Data System (ADS)

Christine, Adika A.; Kibet, Joshua K.; Kiprop, Ambsrose K.; Were, Munyendo L.

2018-03-01

Numerous deleterious impacts of anthropogenic activities on water quality are typically observed in areas bursting with mineral exploitation, agricultural activities, and industrial processes. Therefore, this contribution details the water quality and water origin in selected hand-dug wells of one the most prominent mining areas in Kenya (Kakamega County). The toxicological impacts of drinking water from a mining site may include cancer and genetic aberrations largely because of the toxic effects of waterborne metals including Hg and As. Accordingly, this study focuses primarily on the investigation of heavy metals, essential elements such as Na and K. Heavy metals and essential elements were determined using spectroscopic and titrimetric techniques. The study revealed that mercury (Hg) concentration ranged between 0.00256 and 0.0611 ± 0.00005 mg/L while arsenic (As) concentration ranged from 0.0103 to 0.0119 ± 0.00005 mg/L. The concentration of potassium ranged from 2.53 to 4.08 ± 0.15 mg/L while that of sodium varied from 6.74 to 9.260 ± 0.2 mg/L. Although the concentration of cadmium was lower than that recommended by W.H.O, the concentrations of Hg, Pb, and As in Kakamega waters were higher than the internationally accepted levels. The generally high level of heavy metals in Kakamega bore-hole waters is, therefore, a public health concern that needs immediate intervention.

Mercury in water and biomass of microbial communities in hot springs of Yellowstone National Park, USA

USGS Publications Warehouse

King, S.A.; Behnke, S.; Slack, K.; Krabbenhoft, D.P.; Nordstrom, D. Kirk; Burr, M.D.; Striegl, Robert G.

2006-01-01

Ultra-clean sampling methods and approaches typically used in pristine environments were applied to quantify concentrations of Hg species in water and microbial biomass from hot springs of Yellowstone National Park, features that are geologically enriched with Hg. Microbial populations of chemically-diverse hot springs were also characterized using modern methods in molecular biology as the initial step toward ongoing work linking Hg speciation with microbial processes. Molecular methods (amplification of environmental DNA using 16S rDNA primers, cloning, denatured gradient gel electrophoresis (DGGE) screening of clone libraries, and sequencing of representative clones) were used to examine the dominant members of microbial communities in hot springs. Total Hg (THg), monomethylated Hg (MeHg), pH, temperature, and other parameters influential to Hg speciation and microbial ecology are reported for hot springs water and associated microbial mats. Several hot springs indicate the presence of MeHg in microbial mats with concentrations ranging from 1 to 10 ng g-1 (dry weight). Concentrations of THg in mats ranged from 4.9 to 120,000 ng g-1 (dry weight). Combined data from surveys of geothermal water, lakes, and streams show that aqueous THg concentrations range from l to 600 ng L-1. Species and concentrations of THg in mats and water vary significantly between hot springs, as do the microorganisms found at each site. ?? 2006.

Total selenium and selenium species in irrigation drain inflows to the Salton Sea, California, April and July 2007

USGS Publications Warehouse

May, Thomas W.; Walther, Michael J.; Saiki, Michael K.; Brumbaugh, William G.

2007-01-01

This report presents the results for two sampling periods during a 4-year monitoring survey to provide a characterization of selenium concentrations in selected irrigation drains flowing into the Salton Sea, California. Total selenium, selenium species, and total suspended solids were determined in water samples, and total selenium was determined in sediment, detritus, and biota that included algae, plankton, midge larvae (family, Chironomidae), and two fish species-western mosquitofish (Gambusia affinis), and sailfin molly (Poecilia latipinna). In addition, sediments were analyzed for percent total organic carbon and particle size. Total selenium concentrations in water for both sampling periods ranged from 1.43 to 47.1 micrograms per liter, predominately as selenate, which is typical of waters leached out of selenium-contaminated marine shales under alkaline and oxidizing conditions. Total selenium concentrations ranged from 0.88 to 20.2 micrograms per gram in biota, and from 0.15 to 28.9 micrograms per gram in detritus and sediment.

Biological effects of tritium on fish cells in the concentration range of international drinking water standards.

PubMed

Stuart, Marilyne; Festarini, Amy; Schleicher, Krista; Tan, Elizabeth; Kim, Sang Bog; Wen, Kendall; Gawlik, Jilian; Ulsh, Brant

2016-10-01

To evaluate whether the current Canadian tritium drinking water limit is protective of aquatic biota, an in vitro study was designed to assess the biological effects of low concentrations of tritium, similar to what would typically be found near a Canadian nuclear power station, and higher concentrations spanning the range of international tritium drinking water standards. Channel catfish peripheral blood B-lymphoblast and fathead minnow testis cells were exposed to 10-100,000 Bq l(-1) of tritium, after which eight molecular and cellular endpoints were assessed. Increased numbers of DNA strand breaks were observed and ATP levels were increased. There were no increases in γH2AX-mediated DNA repair. No differences in cell growth were noted. Exposure to the lowest concentrations of tritium were associated with a modest increase in the viability of fathead minnow testicular cells. Using the micronucleus assay, an adaptive response was observed in catfish B-lymphoblasts. Using molecular endpoints, biological responses to tritium in the range of Canadian and international drinking water standards were observed. At the cellular level, no detrimental effects were noted on growth or cycling, and protective effects were observed as an increase in cell viability and an induced resistance to a large challenge dose.

Mercury distribution in Douro estuary (Portugal).

PubMed

Ramalhosa, E; Pereira, E; Vale, C; Válega, M; Monterroso, P; Duarte, A C

2005-11-01

Determinations of dissolved reactive and total dissolved mercury, particulate and sedimentary mercury, dissolved organic carbon (DOC), particulate organic carbon (POC) and suspended particulate matter (SPM) have been made in the estuary of river Douro, in northern Portugal. The estuary was stratified by salinity along most of its length, it had low concentrations of SPM, typically <20 mg dm(-3), and concentrations of DOC in the range <1.0-1.8 mg dm(-3). The surface waters had a maximum dissolved concentration of reactive mercury of about 10 ng dm(-3), whereas for the more saline bottom waters it was about 65 ng dm(-3). The surface waters had maximum concentrations of total suspended particulate mercury of approximately 7 microg g(-1) and the bottom waters were always <1 microg g(-1). Concentrations of mercury in sediments was low and in the range from 0.06 to 0.18 microg g(-1). The transport of mercury in surface waters was mainly associated with organic-rich particulate matter, while in bottom waters the dissolved phase transport of mercury is more important. Lower particulate organic matter, formation of chlorocomplexes in more saline waters and eventually the presence of colloids appear to explain the difference of mercury partitioning in Douro estuarine waters.

Elemental distribution in seaweed, Gelidium abbottiorum along the KwaZulu-Natal Coastline, South Africa.

PubMed

Misheer, Natasha; Kindness, Andrew; Jonnalagadda, Sreekanth B

2006-01-01

The total concentrations of 7 selected metals, namely manganese, iron, zinc, titanium, boron, arsenic and mercury, were monitored for one annual cycle covering four seasons in the seaweed, Gelidium abbottiorum, at four sampling sites at Zinkwasi, Ballito, Treasure beach and Park Rynie along the South-East coastline of KwaZulu-Natal, South Africa to assess the current status of the marine environment. Inductively Coupled Plasma Optical Emission Spectrophotometry, Mercury Cold Vapour AAS, and Hydride Generation AAS were used for the determination of metal concentrations. Mn concentrations were particularly high in the G. abbottiorum species, followed by Fe, As and B concentrations which were in the 3-8 ppm range. Ti and Zn were in the 100-400 ppb range, while Hg was low and below 100 ppb. A typical sample of G. abbottiorum at Treasure beach, a site close to Durban metropolis in winter had Mn (8.6 ppm), Fe (4.6 ppm), As (5.6 ppm), B (3.0 ppm), Ti (420 ppb), Zn (167 ppb) and Hg (7.5 ppb). All metals recorded a decrease in concentrations from winter to spring with the exception of Hg. The Hg levels increased considerably from winter to spring.

Aerosol effects on the UV irradiance in Santiago de Chile

NASA Astrophysics Data System (ADS)

Cordero, R. R.; Seckmeyer, G.; Damiani, A.; Jorquera, J.; Carrasco, J.; Muñoz, R.; Da Silva, L.; Labbe, F.; Laroze, D.

2014-11-01

Santiago de Chile (33°27‧ S-70°41‧ W) is a mid-latitude city of 6 million inhabitants with a complicated surrounding topography. Aerosol extinction in Santiago is determined by the semi-arid local climate, the urban pollution, a regional subsidence thermal inversion layer, and the boundary-layer wind airflow. In this paper we report on spectral measurements of the surface irradiance (at 290-600 nm wavelength range) carried out during 2013 in the heart of the city by using a double monochromator-based spectroradiometer system. These measurements were used to assess the effect of local aerosols, paying particular attention to the ultraviolet (UV) range. We found that the aerosol optical depth (AOD) exhibited variations likely related to changes in the subsidence thermal inversion and in the boundary-layer winds. Although the AOD at 350 nm typically ranged from 0.2 to 0.3, peak values of about 0.7 were measured. The AOD diminished with the wavelength and typically ranged from 0.1 to 0.2 at 550 nm. Our AOD data were found to be consistent with measurements of the particulate matter (PM) mass concentration.

Robust encoding of stimulus identity and concentration in the accessory olfactory system.

PubMed

Arnson, Hannah A; Holy, Timothy E

2013-08-14

Sensory systems represent stimulus identity and intensity, but in the neural periphery these two variables are typically intertwined. Moreover, stable detection may be complicated by environmental uncertainty; stimulus properties can differ over time and circumstance in ways that are not necessarily biologically relevant. We explored these issues in the context of the mouse accessory olfactory system, which specializes in detection of chemical social cues and infers myriad aspects of the identity and physiological state of conspecifics from complex mixtures, such as urine. Using mixtures of sulfated steroids, key constituents of urine, we found that spiking responses of individual vomeronasal sensory neurons encode both individual compounds and mixtures in a manner consistent with a simple model of receptor-ligand interactions. Although typical neurons did not accurately encode concentration over a large dynamic range, from population activity it was possible to reliably estimate the log-concentration of pure compounds over several orders of magnitude. For binary mixtures, simple models failed to accurately segment the individual components, largely because of the prevalence of neurons responsive to both components. By accounting for such overlaps during model tuning, we show that, from neuronal firing, one can accurately estimate log-concentration of both components, even when tested across widely varying concentrations. With this foundation, the difference of logarithms, log A - log B = log A/B, provides a natural mechanism to accurately estimate concentration ratios. Thus, we show that a biophysically plausible circuit model can reconstruct concentration ratios from observed neuronal firing, representing a powerful mechanism to separate stimulus identity from absolute concentration.

Antibiotic contamination in a typical developing city in south China: occurrence and ecological risks in the Yongjiang River impacted by tributary discharge and anthropogenic activities.

PubMed

Xue, Baoming; Zhang, Ruijie; Wang, Yinghui; Liu, Xiang; Li, Jun; Zhang, Gan

2013-06-01

The occurrence and distribution of ten selected antibiotics from three groups (sulfonamides, macrolides, and trimethoprim) were investigated in the Yongjiang River, which flows through Nanning City, a typical developing city in China. The study also assessed the ecological risks and the potential effects caused by discharge from tributaries and anthropogenic activities. Concentrations of most of the antibiotics were elevated along the section of the river in the urban area, highlighting the significant impact of high population density and human activities on the presence of antibiotics in the environment. The concentrations in the tributaries (ranged from not detected to 1336ngL(-1)) were generally higher than those in the main stream (ranged from not detected to 78.8ngL(-1)), but both areas contained the same predominant antibiotics, revealing the importance of tributary discharge as a source of antibiotic pollution. A risk assessment for the surface water contamination revealed that sulfamethoxazole and erythromycin posed high ecological risks to the most sensitive aquatic organisms (Synechococcus leopoliensis and Pseudokirchneriella subcapitata, respectively) in the midstream and some tributaries. Most of the selected antibiotics presented high ecological risks (risk quotients up to 95) in the sediments. Copyright © 2013 Elsevier Inc. All rights reserved.

Microbial degradation of livestock-generated ammonia using biofilters at typical ambient temperatures.

PubMed

Kalingan, A E; Liao, Chung-Min; Chen, Jein-Wen; Chen, Szu-Chieh

2004-01-01

The purpose of this research was to neutralize livestock-generated ammonia by using biofilters packed with inexpensive inorganic and organic packing material combined with multicultural microbial load at typical ambient temperatures. Peat and inorganic supporting materials were used as biofiltration matrix packed in a perfusion column through which gas was transfused. Results show the ammonia removal significantly fell in between 99 and 100% when ammonia concentration of 200 ppmv was used at different gas flow rates ranged from 0.030 to 0.060 m3 h(-1) at a fluctuating room temperature of 27.5 +/- 4.5 C (Mean +/- SD). Under these conditions, the emission concentration of ammonia that is liberated after biofiltration is less than 1 ppmv (0.707 mg m(-3)) over the period of our study, suggesting the usage of low-cost biofiltration systems for long-term function is effective at wider ranges of temperature fluctuations. The maximum (100%) ammonia removal efficiency was obtained in this biofilter was having an elimination capacity of 2.217 g m(-3) h(-1). This biofilter had high nitrification efficiencies and hence controlled ammonia levels with the reduced backpressure. The response of this biofilter to shut down and start up operation showed that the biofilm has a superior stability.

Modeling the effects of sodium chloride, acetic acid, and intracellular pH on survival of Escherichia coli O157:H7.

PubMed

Hosein, Althea M; Breidt, Frederick; Smith, Charles E

2011-02-01

Microbiological safety has been a critical issue for acid and acidified foods since it became clear that acid-tolerant pathogens such as Escherichia coli O157:H7 can survive (even though they are unable to grow) in a pH range of 3 to 4, which is typical for these classes of food products. The primary antimicrobial compounds in these products are acetic acid and NaCl, which can alter the intracellular physiology of E. coli O157:H7, leading to cell death. For combinations of acetic acid and NaCl at pH 3.2 (a pH value typical for non-heat-processed acidified vegetables), survival curves were described by using a Weibull model. The data revealed a protective effect of NaCl concentration on cell survival for selected acetic acid concentrations. The intracellular pH of an E. coli O157:H7 strain exposed to acetic acid concentrations of up to 40 mM and NaCl concentrations between 2 and 4% was determined. A reduction in the intracellular pH was observed for increasing acetic acid concentrations with an external pH of 3.2. Comparing intracellular pH with Weibull model predictions showed that decreases in intracellular pH were significantly correlated with the corresponding times required to achieve a 5-log reduction in the number of bacteria.

Vehicle occupant exposure to carbon monoxide.

PubMed

Koushki, P A; al-Dhowalia, K H; Niaizi, S A

1992-12-01

This paper focuses on the auto commuting micro-environment and presents typical carbon monoxide (CO) concentrations to which auto commuters in central Riyadh, Saudi Arabia were exposed. Two test vehicles traveling over four main arterial roadways were monitored for inside and outside CO levels during eighty peak and off-peak hours extending over an eight-month period. The relative importance of several variables which explained the variability in CO concentrations inside autos was also assessed. It was found that during peak hours auto commuters were exposed to mean CO levels that ranged from 30 to 40 ppm over trips that typically took between 25 to 40 minutes. The mean ratio of inside to outside CO levels was 0.84. Results of variance component analyses indicated that the most important variables affecting CO concentrations inside autos were, in addition to the smoking of vehicle occupants, traffic volume, vehicle speed, period of day and wind velocity. An increase in traffic volume from 1,000 to 5,000 vehicles per hour (vph) increased mean CO level exposure by 71 percent. An increase in vehicle speed from 14 to 55 km/h reduced mean CO exposure by 36 percent. The number of traffic interruptions had a moderate effect on mean concentrations of CO inside vehicles.

Polybrominated diphenyl ethers in e-waste: level and transfer in a typical e-waste recycling site in Shanghai, Eastern China.

PubMed

Li, Yue; Duan, Yan-Ping; Huang, Fan; Yang, Jing; Xiang, Nan; Meng, Xiang-Zhou; Chen, Ling

2014-06-01

Very few data for polybrominated diphenyl ethers (PBDEs) were available in the electronic waste (e-waste) as one of the most PBDEs emission source. This study reported concentrations of PBDEs in e-waste including printer, rice cooker, computer monitor, TV, electric iron and water dispenser, as well as dust from e-waste, e-waste dismantling workshop and surface soil from inside and outside of an e-waste recycling plant in Shanghai, Eastern China. The results showed that PBDEs were detected in the majority of e-waste, and the concentrations of ΣPBDEs ranged from not detected to 175 g/kg, with a mean value of 10.8 g/kg. PBDEs were found in TVs made in China after 1990. The mean concentrations of ΣPBDEs in e-waste made in Korea, Japan, Singapore and China were 1.84 g/kg, 20.5 g/kg, 0.91 g/kg, 4.48 g/kg, respectively. The levels of ΣPBDEs in e-waste made in Japan far exceed the threshold limit of RoHS (1.00 g/kg). BDE-209 dominated in e-waste, accounting for over 93%. The compositional patterns of PBDEs congeners resembled the profile of Saytex 102E, indicating the source of deca-BDE. Among the samples of dust and surface soil from a typical e-waste recycling site, the highest concentrations of Σ18PBDEs and BDE-209 were found in dust in e-waste, ranging from 1960 to 340,710 ng/g and from 910 to 320,400 ng/g, which were 1-2 orders of magnitude higher than other samples. It suggested that PBDEs released from e-waste via dust, and then transferred to surrounding environment. Copyright © 2013 Elsevier Ltd. All rights reserved.

Analysis and clinical findings of cases positive for the novel synthetic cannabinoid receptor agonist MDMB-CHMICA.

PubMed

Seywright, Alice; Torrance, Hazel J; Wylie, Fiona M; McKeown, Denise A; Lowe, David J; Stevenson, Richard

2016-09-01

MDMB-CHMICA is a synthetic cannabinoid receptor agonist which has caused concern due to its presence in cases of adverse reaction and death. 43 cases of suspected synthetic cannabinoid ingestion were identified from patients presenting at an Emergency Department and from post-mortem casework. These were subjected to liquid-liquid extraction using tertiary-butyl methyl ether and quantitatively analysed by Electrospray Ionisation Liquid Chromatography-tandem Mass Spectrometry. For positive samples, case and clinical details were sought and interrogated. 11 samples were found positive for MDMB-CHMICA. Concentrations found ranged from <1 to 22 ng/mL (mean: 6 ng/mL, median: 3 ng/mL). The age range was 15-44 years (mean: 26 years, median: 21 years), with the majority (82%) of positive results found in males. Clinical presentations included hypothermia, hypoglycaemia, syncope, recurrent vomiting, altered mental state and serotonin toxicity, with corresponding concentrations of MDMB-CHMICA as low as <1 ng/mL. Duration of hospitalisation ranged from 3 to 24 h (mean: 12 h, median: 8 h). The concentration range presented in this case series is indicative of MDMB-CHMICA having a high potency, as is known to be the case for other synthetic cannabinoid receptor agonists. The age range and gender representation were consistent with that reported for users of other drugs of this type. The clinical presentations observed were typical of synthetic cannabinoid receptor agonists and show the difficulties in identifying reactions potentially associated with drugs of this type. The range of MDMB-CHMICA concentrations in Emergency Department presentations (n = 9) and post-mortem cases (n = 2) was reported. No correlation between the concentration of this drug and clinical presentation or cause of death was reported in this sample. However, the potential for harm associated with low concentrations of MDMB-CHMICA and the symptoms of toxicity being non-specific were highlighted.

Occurrence of perfluoroalkyl sulfonates and carboxylates in German drinking water sources compared to other countries.

PubMed

Lange, F T; Wenz, M; Schmidt, C K; Brauch, H-J

2007-01-01

Different homologues of C4 to C8 perfluoroalkyl carboxylates (PFCAs) and perfluoroalkyl sulfonates (PFASs) were detected in German surface waters, bank filtrates, artificially recharged groundwaters, and drinking waters. If no point sources are located nearby, the typically measured levels are in the low ng/L range. In the presence of point sources, such as a fluorochemical production site, a leaching agricultural fertilizer contaminated with PFCAs and PFASs, or drained PFC containing fire-fighting foams, much higher concentrations in the microg/L range occur. This situation is similar in Germany and other countries.

Ocean color measurements

NASA Technical Reports Server (NTRS)

Gordon, H. R.; Austin, R. W.; Clark, D. K.; Hovis, W. A.; Yentsch, C. S.

1985-01-01

Ocean color observations by the Coastal Zone color scanner (CZCS) aboard the Nimbus-7 satellite are discussed, together with the factors contributing to the 'apparent' color of the ocean. The CZCS optical systems and the tecniques for extraction of the phytoplankton pigment concentration and the diffuse attenuation coefficient K from the 'apparent' water color are described in detail. Special consideration is given to the use of biooptical algorithms and the development of the K algorithm for the CZCS imagery. It is shown that under typical atmospheric conditions, the pigment concentration can be extracted from the satellite imagery to within + or - 30 percent over concentration ranges from 0 to 5 mg/cu m for the Morel case 1 water (Morel and Prieur, 1977), to which the oceanic waters belong as a rule.

Influence of temperature, needle gauge and injection rate on the size distribution, concentration and acoustic responses of ultrasound contrast agents at high frequency.

PubMed

Sun, Chao; Panagakou, Ioanna; Sboros, Vassilis; Butler, Mairead B; Kenwright, David; Thomson, Adrian J W; Moran, Carmel M

2016-08-01

This paper investigated the influence of needle gauge (19G and 27G), injection rate (0.85ml·min(-1), 3ml·min(-1)) and temperature (room temperature (RT) and body temperature (BT)) on the mean diameter, concentration, acoustic attenuation, contrast to tissue ratio (CTR) and normalised subharmonic intensity (NSI) of three ultrasound contrast agents (UCAs): Definity, SonoVue and MicroMarker (untargeted). A broadband substitution technique was used to acquire the acoustic properties over the frequency range 17-31MHz with a preclinical ultrasound scanner Vevo770 (Visualsonics, Canada). Significant differences (P<0.001-P<0.05) between typical in vitro setting (19G needle, 3ml·min(-1) at RT) and typical in vivo setting (27G needle, 0.85ml·min(-1) at BT) were found for SonoVue and MicroMarker. Moreover we found that the mean volume-based diameter and concentration of both SonoVue and Definity reduced significantly when changing from typical in vitro to in vivo experimental set-ups, while those for MicroMarker did not significantly change. From our limited measurements of Definity, we found no significant change in attenuation, CTR and NSI with needle gauge. For SonoVue, all the measured acoustic properties (attenuation, CTR and NSI) reduced significantly when changing from typical in vitro to in vivo experimental conditions, while for MicroMarker, only the NSI reduced, with attenuation and CTR increasing significantly. These differences suggest that changes in physical compression and temperature are likely to alter the shell structure of the UCAs resulting in measureable and significant changes in the physical and high frequency acoustical properties of the contrast agents under typical in vitro and preclinical in vivo experimental conditions. Copyright © 2016 Elsevier B.V. All rights reserved.

Partitioning in REE-saturating minerals - Theory, experiment, and modelling of whitlockite, apatite, and evolution of lunar residual magmas

NASA Technical Reports Server (NTRS)

Jolliff, Bradley L.; Haskin, Larry A.; Colson, Russell O.; Wadhwa, Meenakshi

1993-01-01

Compositions, including REEs determined by ion microprobe, of apatite and whitlockite in lunar rock assemblages rich in incompatible trace elements, are presented. Concentrations of REEs in lunar whitlockites are high, ranging from about 1.2 to 2.1 REEs (lanthanides + Y) per 56 oxygens. This slightly exceeds the level of two REE atoms per 56 oxygens at which the dominant substitution theoretically becomes saturated. This saturation effect leads to whitlockite REE(3+) D values at typical lunar whitlockite REE concentrations which are 30-40 percent lower than the D values at low concentrations. The halogen-to-phosphorous ratio in lunar melts is a key factor determining the REE distribution with crystalline assemblages. As long as P and REE concentrations of melts are in KREEP-like proportions, one or both of the phosphates will saturate in melts at similar REE concentrations.

Validation of Ogawa passive samplers for the determination of gaseous ammonia concentrations in agricultural settings

NASA Astrophysics Data System (ADS)

Roadman, M. J.; Scudlark, J. R.; Meisinger, J. J.; Ullman, W. J.

The Ogawa passive sampler (Ogawa USA, Pompano Beach, Florida) is a useful tool for monitoring atmospheric ammonia (NH 3(g)) concentrations and assessing the effects of agricultural waste management practices on NH 3(g) emissions. The Ogawa sampler, with filter-discs impregnated with citric acid, was used to trap and determine NH 3(g) concentrations in a variety of agricultural settings. A wide range of NH 3(g) concentrations can be monitored by varying the sampler exposure time, provided that no more than ˜10 μg of NH 3-N are adsorbed on the acid-coated filters. Concentrations less than 1 μg NH 3-N m -3 can be detected using long deployments (⩽14 days), while concentrations as great as 10 mg NH 3-N m -3 may be determined in very short (e.g. 5 min) deployments. Reproducibility ranged from 5% to 10% over the range of concentrations studied and passive determinations of NH 3(g) were similar to those determined using dilute-acid gas scrubbers. Background levels of NH 3(g) at a non-agricultural site in southern Delaware were typically <1 μg NH 3-N m -3. The air entering a chicken house was 10 μg NH 3-N m -3, reflecting the background levels in agricultural settings in this region. Within the house, concentrations ⩽8.5 mg NH 3-N m -3 were observed, reflecting the high rates of NH 3(g) emission from chicken excreta. Using measured NH 3(g) concentrations and poultry house ventilation rates, we estimate that each broiler grown to production size over 6 weeks contributes approximately 19±3 g of NH 3-N to the atmosphere, a value consistent with other published results.

Mercury in wetlands at the Glacial Ridge National Wildlife Refuge, northwestern Minnesota, 2007-9

USGS Publications Warehouse

Cowdery, Timothy K.; Brigham, Mark E.

2013-01-01

The Glacial Ridge National Wildlife Refuge was established in 2004 on land in northwestern Minnesota that had previously undergone extensive wetland and prairie restorations. About 7,000 acres of drained wetlands were restored to their original hydrologic function and aquatic ecosystem. During 2007–9, the U.S. Geological Survey, in cooperation with the U.S. Fish and Wildlife Service and the Red Lake Watershed District, analyzed mercury concentrations in wetland water and sediment to evaluate the effect of wetland restoration on mercury methylation. The wetland waters sampled generally were of the calcium/magnesium bicarbonate type. Nitrogen in water was mostly in the form of dissolved-organic nitrogen, with very low dissolved-nitrate and dissolved-ammonia concentrations. About 71 percent of all phosphorus in water was dissolved, with one-half of that in the form of orthophosphorus. Wetland water had total-mercury and methylmercury concentrations ranging from 1.5 to 20 nanograms per liter (ng/L) and 0.2 to 16 ng/L, respectively. Median concentrations were 7.1 and 2.9 ng/L, respectively. About one-half of the mercury in wetland water samples was in the form of methylmercury, but this form ranged from 7 to 81 percent of each sample. Compared to concentrations in stream sediment samples collected throughout the United States, Glacial Ridge National Wildlife Refuge wetland sediment samples contained typical total-mercury concentrations, but methylmercury concentrations were nearly twice as high. The maximum concentration measured in Glacial Ridge National Wildlife Refuge wetland water approached the highest published water methylmercury concentration in uncontaminated waters of which we are aware. However, the upper quartile of water methylmercury concentrations is similar to concentrations reported for some impoundments and wetlands in northwestern Minnesota and North Dakota. Methylmercury concentrations in sampled wetlands were much higher than those from typical lakes or flowing streams throughout the United States. The high concentrations of methylmercury measured in sampled wetlands indicate the potential for substantial methylmercury concentrations in aquatic biota and wildlife that consume those biota. These wetlands also are a methylmercury source for downstream lakes and rivers. The high concentrations of methylmercury in water, its bioaccumulation potential, and its known toxicity in aquatic birds and food webs highlight a need to assess methylmercury in the biota within these ecosystems. Better understanding of factors that control methylmercury production concentrations within aquatic food webs in ecosystems of the Glacial Ridge National Wildlife Refuge would enable resource managers to better understand and manage risk to wildlife.

Occurrence of fibrates and their metabolites in source and drinking water in Shanghai and Zhejiang, China.

PubMed

Ido, Akiko; Hiromori, Youhei; Meng, Liping; Usuda, Haruki; Nagase, Hisamitsu; Yang, Min; Hu, Jianying; Nakanishi, Tsuyoshi

2017-04-12

Fibrates, which are widely used lipidaemic-modulating drugs, are emerging environmental pollutants. However, fibrate concentrations in the environment have not been thoroughly surveyed. Here, we determined concentrations of the most commonly used fibrates and their metabolites in source water and drinking water samples from ten drinking water treatment plants in Shanghai and Zhejiang, China, using solid-phase extraction and liquid chromatography-tandem mass spectrometry. All the target compounds were detected in at least some of the source water samples, at concentrations ranging from 0.04 ng/L (fenofibrate) to 1.53 ng/L (gemfibrozil). All the compounds except fenofibrate were also detected in at least some of the drinking water samples, at recoveries ranging from 35.5% to 91.7%, suggesting that these compounds are poorly removed by typical drinking water treatment processes. In a peroxisome proliferator-activated receptor α agonistic activity assay, the target compounds showed no significant activity at nanogram per litre concentrations; therefore, our results suggest that the fibrate concentrations in drinking water in Shanghai and Zhejiang, China do not significantly affect human health. However, because of the increasing westernization of the Chinese diet, fibrate use may increase, and thus monitoring fibrate concentrations in aquatic environments and drinking water in China will become increasingly important.

Occurrence of fibrates and their metabolites in source and drinking water in Shanghai and Zhejiang, China

PubMed Central

Ido, Akiko; Hiromori, Youhei; Meng, Liping; Usuda, Haruki; Nagase, Hisamitsu; Yang, Min; Hu, Jianying; Nakanishi, Tsuyoshi

2017-01-01

Fibrates, which are widely used lipidaemic-modulating drugs, are emerging environmental pollutants. However, fibrate concentrations in the environment have not been thoroughly surveyed. Here, we determined concentrations of the most commonly used fibrates and their metabolites in source water and drinking water samples from ten drinking water treatment plants in Shanghai and Zhejiang, China, using solid-phase extraction and liquid chromatography–tandem mass spectrometry. All the target compounds were detected in at least some of the source water samples, at concentrations ranging from 0.04 ng/L (fenofibrate) to 1.53 ng/L (gemfibrozil). All the compounds except fenofibrate were also detected in at least some of the drinking water samples, at recoveries ranging from 35.5% to 91.7%, suggesting that these compounds are poorly removed by typical drinking water treatment processes. In a peroxisome proliferator-activated receptor α agonistic activity assay, the target compounds showed no significant activity at nanogram per litre concentrations; therefore, our results suggest that the fibrate concentrations in drinking water in Shanghai and Zhejiang, China do not significantly affect human health. However, because of the increasing westernization of the Chinese diet, fibrate use may increase, and thus monitoring fibrate concentrations in aquatic environments and drinking water in China will become increasingly important. PMID:28401920

Occurrence of fibrates and their metabolites in source and drinking water in Shanghai and Zhejiang, China

NASA Astrophysics Data System (ADS)

Ido, Akiko; Hiromori, Youhei; Meng, Liping; Usuda, Haruki; Nagase, Hisamitsu; Yang, Min; Hu, Jianying; Nakanishi, Tsuyoshi

2017-04-01

Fibrates, which are widely used lipidaemic-modulating drugs, are emerging environmental pollutants. However, fibrate concentrations in the environment have not been thoroughly surveyed. Here, we determined concentrations of the most commonly used fibrates and their metabolites in source water and drinking water samples from ten drinking water treatment plants in Shanghai and Zhejiang, China, using solid-phase extraction and liquid chromatography-tandem mass spectrometry. All the target compounds were detected in at least some of the source water samples, at concentrations ranging from 0.04 ng/L (fenofibrate) to 1.53 ng/L (gemfibrozil). All the compounds except fenofibrate were also detected in at least some of the drinking water samples, at recoveries ranging from 35.5% to 91.7%, suggesting that these compounds are poorly removed by typical drinking water treatment processes. In a peroxisome proliferator-activated receptor α agonistic activity assay, the target compounds showed no significant activity at nanogram per litre concentrations; therefore, our results suggest that the fibrate concentrations in drinking water in Shanghai and Zhejiang, China do not significantly affect human health. However, because of the increasing westernization of the Chinese diet, fibrate use may increase, and thus monitoring fibrate concentrations in aquatic environments and drinking water in China will become increasingly important.

Concentrated dispersions of equilibrium protein nanoclusters that reversibly dissociate into active monomers

NASA Astrophysics Data System (ADS)

Truskett, Thomas M.; Johnston, Keith; Maynard, Jennifer; Borwankar, Ameya; Miller, Maria; Wilson, Brian; Dinin, Aileen; Khan, Tarik; Kaczorowski, Kevin

2012-02-01

Stabilizing concentrated protein solutions is of wide interest in drug delivery. However, a major challenge is how to reliably formulate concentrated, low viscosity (i.e., syringeable) solutions of biologically active proteins. Unfortunately, proteins typically undergo irreversible aggregation at intermediate concentrations of 100-200 mg/ml. In this talk, I describe how they can effectively avoid these intermediate concentrations by reversibly assembling into nanoclusters. Nanocluster assembly is achieved by balancing short-ranged, cosolute-induced attractions with weak, longer-ranger electrostatic repulsions near the isoelectric point. Theory predicts that native proteins are stabilized by a self-crowding mechanism within the concentrated environment of the nanoclusters, while weak cluster-cluster interactions can result in colloidally-stable dispersions with moderate viscosities. I present experimental results where this strategy is used to create concentrated antibody dispersions (up to 260 mg/ml) comprising nanoclusters of proteins [monoclonal antibody 1B7, polyclonal sheep Immunoglobin G and bovine serum albumin], which upon dilution in vitro or administration in vivo, are conformationally stable and retain activity.

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.

VOC source identification from personal and residential indoor, outdoor and workplace microenvironment samples in EXPOLIS-Helsinki, Finland

NASA Astrophysics Data System (ADS)

Edwards, Rufus D.; Jurvelin, J.; Koistinen, K.; Saarela, K.; Jantunen, M.

Principal component analyses (varimax rotation) were used to identify common sources of 30 target volatile organic compounds (VOCs) in residential outdoor, residential indoor and workplace microenvironment and personal 48-h exposure samples, as a component of the EXPOLIS-Helsinki study. Variability in VOC concentrations in residential outdoor microenvironments was dominated by compounds associated with long-range transport of pollutants, followed by traffic emissions, emissions from trees and product emissions. Variability in VOC concentrations in environmental tobacco smoke (ETS) free residential indoor environments was dominated by compounds associated with indoor cleaning products, followed by compounds associated with traffic emissions, long-range transport of pollutants and product emissions. Median indoor/outdoor ratios for compounds typically associated with traffic emissions and long-range transport of pollutants exceeded 1, in some cases quite considerably, indicating substantial indoor source contributions. Changes in the median indoor/outdoor ratios during different seasons reflected different seasonal ventilation patterns as increased ventilation led to dilution of those VOC compounds in the indoor environment that had indoor sources. Variability in workplace VOC concentrations was dominated by compounds associated with traffic emissions followed by product emissions, long-range transport and air fresheners. Variability in VOC concentrations in ETS free personal exposure samples was dominated by compounds associated with traffic emissions, followed by long-range transport, cleaning products and product emissions. VOC sources in personal exposure samples reflected the times spent in different microenvironments, and personal exposure samples were not adequately represented by any one microenvironment, demonstrating the need for personal exposure sampling.

Rheological properties of the product slurry of the Nitrate to Ammonia and Ceramic (NAC) process

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

Muguercia, I.; Yang, G.; Ebadian, M.A.

The Nitrate to Ammonia and Ceramic (NAC) process is an innovative technology for immobilizing the liquid from Low Level radioactive Waste (LLW). An experimental study was conducted to measure the rheological properties of the pipe flow of the NAC product slurry. Test results indicate that the NAC product slurry has a profound rheological behavior. At low solids concentration, the slurry exhibits a typical dilatant fluid (or shear thinning)fluid. The transition from dilatant fluid to pseudo-plastic fluid will occur at between 25% to 30% solids concentration in temperature ranges of 50--80{degree}C. Correlation equations are developed based on the test data.

Bromine-Chlorine Coupling in the Antarctic Ozone Hole

NASA Technical Reports Server (NTRS)

Danilin, Michael Y.; Sze, Nien-Dak; Ko, Malcolm K. W.; Rodriquez, Jose M.; Prather, Michael J.

1996-01-01

The contribution from the chlorine and bromine species in the formation of the Antarctic ozone hole is evaluated. Since chlorine and bromine compounds are of different industrial origin, it is desirable, from a policy point of view, to be able to attribute chlorine-catalyzed loss of ozone with those reactions directly involving chlorine species, and likewise for bromine-catalyzed loss. In the stratosphere, however, most of the chemical families are highly coupled, and, for example, changes in the chlorine abundance will alter the partitioninig in other families and thus the rate of ozone loss. This modeling study examines formation of the Antarctic ozone hole for a wide range of bromine concentrations (5 - 25 pptv) and for chlorine concentrations typical of the last two decades (1.5, 2.5 and 3.5 ppbv). We follow the photochemical evolution of a single parcel of air, typical of the inner Antarctic vortex (50 mbar, 70 deg. S, NO(sub y) = 2 ppbv, with Polar Stratospheric Clouds(PSC)) from August 1 to November 1. For all of these ranges of chlorine and bromine loading, we would predict a substantial ozone hole (local depletion greater than 90%) within the de-nitrified, PSC- perturbed vortex. The contributions of the different catalytic cycles responsible for ozone loss are tabulated. The deep minimum in ozone is driven primarily by the chlorine abundance. As bromine levels decrease, the magnitude of the chlorine-catalyzed ozone loss increases to take up the slack. This is because bromine suppresses ClO by accelerating the conversion of ClO an Cl2O2 back to HCI. For this range of conditions, the local relative efficiency of ozone destruction per bromine atom to that per chlorine atom (alpha-factor) ranges from 33 to 55, decreasing with increase of bromine.

Groundwater-quality data in the northern Coast Ranges study unit, 2009: Results from the California GAMA Program

USGS Publications Warehouse

Mathany, Timothy M.; Dawson, Barbara J.; Shelton, Jennifer L.; Belitz, Kenneth

2011-01-01

This study did not attempt to evaluate the quality of water delivered to consumers; after withdrawal from the ground, untreated groundwater typically is treated, disinfected, and (or) blended with other waters to maintain water quality. Regulatory benchmarks apply to water that is served to the consumer, not to untreated groundwater. However, to provide some context for the results, concentrations of constituents measured in the untreated groundwa

Technology Assessment of Selected Hazardous Waste Minimization Process Changes

DTIC Science & Technology

1988-03-01

the bath and allow buildup of trivalent chromium in 16 solution. Platinum has had limited success, but it allows buildup of trivalent -hromium. The...occurs mainly from occupational exposure. Trivalent compounds are not highly toxic, but excessive exposure to dust or mists of hexavalent chromium ...particulate and most likely in the trivalent state. Chromium concentration in soils can range from 5 to 200 ppm. The clay fraction of soils typically has a

Distributions and seasonal variations of dissolved carbohydrates in the Jiaozhou Bay, China

NASA Astrophysics Data System (ADS)

Yang, Gui-Peng; Zhang, Yan-Ping; Lu, Xiao-Lan; Ding, Hai-Bing

2010-06-01

Surface seawater samples were collected in the Jiaozhou Bay, a typical semi-closed basin located at the western part of the Shandong Peninsula, China, during four cruises. Concentrations of monosaccharides (MCHO), polysaccharides (PCHO) and total dissolved carbohydrates (TCHO) were measured with the 2,4,6-tripyridyl- s-triazine spectroscopic method. Concentrations of TCHO varied from 10.8 to 276.1 μM C for all samples and the ratios of TCHO to dissolved organic carbon (DOC) ranged from 1.1 to 67.9% with an average of 10.1%. This result indicated that dissolved carbohydrates were an important constituent of DOC in the surface seawater of the Jiaozhou Bay. In all samples, the concentrations of MCHO ranged from 2.9 to 65.9 μM C, comprising 46.1 ± 16.6% of TCHO on average, while PCHO ranged from 0.3 to 210.2 μM C, comprising 53.9 ± 16.6% of TCHO on average. As a major part of dissolved carbohydrates, the concentrations of PCHO were higher than those of MCHO. MCHO and PCHO accumulated in January and July, with minimum average concentration in April. The seasonal variation in the ratios of TCHO to DOC was related to water temperature, with high values in January and low values in July and October. The concentrations of dissolved carbohydrates displayed a decreasing trend from the coastal to the central areas. Negative correlations between concentrations of TCHO and salinity in July suggested that riverine input around the Jiaozhou Bay had an important effect on the concentrations of dissolved carbohydrates in surface seawater. The pattern of distributions of MCHO and PCHO reported in this study added to the global picture of dissolved carbohydrates distribution.

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.

Distribution and bioavailability of Cr in central Euboea, Greece

NASA Astrophysics Data System (ADS)

Megremi, Ifigeneia

2010-06-01

Plants and soils from central Euboea, were analyzed for Cr(totai), Cr(VI), Ni, Mn, Fe and Zn. The range of metal concentrations in soils is typical to those developed on Fe-Ni laterites and ultramafic rocks. Their bioavailability was expressed in terms of concentrations extractable with EDTA and 1 M HNO3, with EDTA having a limited effect on metal recovery. Cr(VI) concentrations in soils evaluated by alkaline digestion solution were lower than phytotoxic levels. Chromium and Ni — and occasionally Zn — in the majority of plants were near or above toxicity levels. Cr(VI) concentrations in plants were extremely low compared to total chromium concentrations. Cr(total) in ground waters ranged from <1 μg.L-1 to 130 μg.L-1, with almost all chromium present as Cr(VI). With the exception of Cr(total) and in some cases Zn, all elements were below regulatory limits for drinking water. On the basis of Ca, Mg, Cr(total) and Si ground waters were classified into three groups: Group(I) with Cr concentrations less than 1 μg.L-1 from a karstic aquifer; Group(II) with average concentrations of 24 μg.L-1 of Cr and relatively high Si associated with ophiolites; and Group(III) with Cr concentrations of up to 130 μg.L-1, likely due to anthropogenic activity. Group(III) is comparable to ground waters from Assopos basin, characterized by high Cr(VI) concentrations, probably due to industrial actrivities.

Colorimetric sensor array for determination and identification of toxic industrial chemicals.

PubMed

Feng, Liang; Musto, Christopher J; Kemling, Jonathan W; Lim, Sung H; Zhong, Wenxuan; Suslick, Kenneth S

2010-11-15

A low-cost yet highly sensitive colorimetric sensor array for the detection and identification of toxic industrial chemicals (TICs) has been developed. The sensor consists of a disposable array of cross-responsive nanoporous pigments whose colors are changed by diverse chemical interactions with analytes. Clear differentiation among 20 different TICs has been easily achieved at both their IDLH (immediately dangerous to life or health) concentration within 2 min of exposure and PEL (permissible exposure limit) concentration within 5 min of exposure with no errors or misclassifications. Detection limits are generally well below the PEL (in most cases below 5% of PEL) and are typically in the low ppb range. The colorimetric sensor array is not responsive to changes in humidity or temperature over a substantial range. The printed arrays show excellent batch to batch reproducibility and long shelf life (greater than 3 months).

Summary of airborne chlorine and hydrogen chloride gas measurements for August 20 and September 5, 1977 Voyager launches at Air Force Eastern Test Range, Florida

NASA Technical Reports Server (NTRS)

Gregory, G. L.; Emerson, B. R., Jr.; Hudgins, C. H.

1978-01-01

Airborne chlorine and hydrogen chloride measurements were made in the tropospheric ground cloud following the Voyager launches of August 20 and September 5, 1977. The maximum observed hydrogen chloride concentration for both launches was about 25 to 30 parts per million (ppm) occurring typically 2 to 6 minutes after launch. By completion of the sampling mission (1-1/2 hours for August, 4-1/2 hours for September), the maximum in-cloud concentration decayed to about 1 to 2 ppm. Maximum observed chlorine concentrations were about 40 to 55 parts per billion (ppb) about 2 to 8 minutes after launch; by about 15 minutes after launch, chlorine concentrations were less than 10 ppb (detection limit). In-cloud chlorine concentrations were well below 1 percent of hydrogen chloride concentrations. The appendix of the report discusses the chlorine instrument and the laboratory evaluation of the detector.

Spectral constraints on models of gas in clusters of galaxies

NASA Technical Reports Server (NTRS)

Henriksen, M. J.; Mushotzky, R.

1985-01-01

The HEAO 1A2 spectra of clusters of galaxies are used to determine the temperature profile which characterizes the X-ray emitting gas. Strong evidence of nonisothermality is found for the Coma, A85, and A1795 clusters. Properties of the cluster potential which binds the gas are calculated for a range of model parameters. The typical binding mass, if the gas is adiabatic, is 2-4E14 solar masses and is quite centrally concentrated. In addition, the Fe abundance in Coma is .26 + or - .06 solar, less than the typical value (.5) found for rich clusters. The results for the gas in Coma may imply a physical description of the cluster which is quite different from what was previously believed.

Arsenic Concentrations and Speciation in Blackwaters of the Great Dismal Swamp, Southeastern Virginia, USA

NASA Astrophysics Data System (ADS)

Batista, F.; Cutter, G. A.; Cutter, L. S.; Johannesson, K. H.

2001-12-01

Arsenic concentrations and speciation were measured in surface water samples collected from the Great Dismal Swamp in southeastern Virginia, USA using, selective hydride generation and atomic adsorption spectroscopy. Phosphate concentrations were also determined in these surface waters using the molybdate blue spectrophotometric method. Great Dismal Swamp waters are characterized as blackwaters, having high dissolved organic carbon (DOC) concentrations that range from 445 iM to 6304 iM, with a mean (n = 12) of 3282+/-2165 iM. pH ranged from 4.30 to 6.42, with a mean (n = 12) of 5.14+/-1.04. The inflow waters (Cypress and Pocosin Swamps) have higher pH's (mean of 6.32+/- 0.10 for n = 5) than waters from Lake Drummond and its immediate inflow and outflow ditches, where the mean pH (n = 7) is 4.30+/-0.04. Total arsenic concentrations in Great Dismal Swamp waters range from 2.18 nM up to 21.42 nM. Phosphate concentrations range from 0.18 iM to 1.42 iM, but are not correlated with arsenate concentrations (r 2 = 0.004). Arsenate typically predominates in oxic, surface waters. However, As(III) was detected at higher concentrations (1 - 17.72 nM, mean value of 8.00+/-5.80 nM for all samples, n = 10) in half of the samples from the lower part of the watershed (i.e., mainly in Lake Drummond and its outflow, the Feeder Ditch; mean of 12.89+/-2.89 nM, n = 5). No methylated species were detected in the selected samples analyzed for organoarsenical forms (monomethyl and dimethyl arsenicals) A strong correlation exists between dissolved As(III) concentrations and dissolved organic carbon concentrations (r2 = 0.88), and this correlation is significant at greater than the 99% confidence level. The high abundance of As(III) in comparison to both thermodynamic predictions, and other surface waters, suggests that either there is a strong anoxic source of this form, or that the high DOC concentrations stabilize it via complexation and slower rate of oxidation.

Effect of gaseous cement industry effluents on four species of microalgae.

PubMed

Talec, Amélie; Philistin, Myrvline; Ferey, Frédérique; Walenta, Günther; Irisson, Jean-Olivier; Bernard, Olivier; Sciandra, Antoine

2013-09-01

Experiments were performed at lab scale in order to test the possibility to grow microalgae with CO2 from gaseous effluent of cement industry. Four microalgal species (Dunaliella tertiolecta, Chlorella vulgaris, Thalassiosira weissflogii, and Isochrysis galbana), representing four different phyla were grown with CO2 enriched air or with a mixture of gasses mimicking the composition of a typical cement flue gas (CFG). In a second stage, the culture submitted to the CFG received an increasing concentration of dust characteristic of cement industry. Results show that growth for the four species is not affected by the CFG. Dust added at realistic concentrations do not have any impact on growth. For dust concentrations in two ranges of magnitude higher, microalgae growth was inhibited. Copyright © 2013 Elsevier Ltd. All rights reserved.

Methane fluxes from tropical coastal lagoons surrounded bymangroves, Yucatán, Mexico

USGS Publications Warehouse

Chuang, Pei-Chuan; Young, Megan B.; Dale, Andrew W.; Miller, Laurence G.; Herrera-Silveira, Jorge A; Paytan, Adina

2017-01-01

Methane concentrations in the water column and emissions to the atmosphere were determined for three tropical coastal lagoons surrounded by mangrove forests on the Yucatán Peninsula, Mexico. Surface water dissolved methane was sampled at different seasons over a period of 2 years in areas representing a wide range of salinities and anthropogenic impacts. The highest surface water methane concentrations (up to 8378 nM) were measured in a polluted canal associated with Terminos Lagoon. In Chelem Lagoon, methane concentrations were typically lower, except in the polluted harbor area (1796 nM). In the relatively pristine Celestún Lagoon, surface water methane concentrations ranged from 41 to 2551 nM. Methane concentrations were negatively correlated with salinity in Celestún, while in Chelem and Terminos high methane concentrations were associated with areas of known pollution inputs, irrespective of salinity. The diffusive methane flux from surface lagoon water to the atmosphere ranged from 0.0023 to 15 mmol CH4 m−2 d−1. Flux chamber measurements revealed that direct methane release as ebullition was up to 3 orders of magnitude greater than measured diffusive flux. Coastal mangrove lagoons may therefore be an important natural source of methane to the atmosphere despite their relatively high salinity. Pollution inputs are likely to substantially enhance this flux. Additional statistically rigorous data collected globally are needed to better consider methane fluxes from mangrove-surrounded coastal areas in response to sea level changes and anthropogenic pollution in order to refine projections of future atmospheric methane budgets.

Methane fluxes from tropical coastal lagoons surrounded by mangroves, Yucatán, Mexico

NASA Astrophysics Data System (ADS)

Chuang, P.-C.; Young, M. B.; Dale, A. W.; Miller, L. G.; Herrera-Silveira, J. A.; Paytan, A.

2017-05-01

Methane concentrations in the water column and emissions to the atmosphere were determined for three tropical coastal lagoons surrounded by mangrove forests on the Yucatán Peninsula, Mexico. Surface water dissolved methane was sampled at different seasons over a period of 2 years in areas representing a wide range of salinities and anthropogenic impacts. The highest surface water methane concentrations (up to 8378 nM) were measured in a polluted canal associated with Terminos Lagoon. In Chelem Lagoon, methane concentrations were typically lower, except in the polluted harbor area (1796 nM). In the relatively pristine Celestún Lagoon, surface water methane concentrations ranged from 41 to 2551 nM. Methane concentrations were negatively correlated with salinity in Celestún, while in Chelem and Terminos high methane concentrations were associated with areas of known pollution inputs, irrespective of salinity. The diffusive methane flux from surface lagoon water to the atmosphere ranged from 0.0023 to 15 mmol CH4 m-2 d-1. Flux chamber measurements revealed that direct methane release as ebullition was up to 3 orders of magnitude greater than measured diffusive flux. Coastal mangrove lagoons may therefore be an important natural source of methane to the atmosphere despite their relatively high salinity. Pollution inputs are likely to substantially enhance this flux. Additional statistically rigorous data collected globally are needed to better consider methane fluxes from mangrove-surrounded coastal areas in response to sea level changes and anthropogenic pollution in order to refine projections of future atmospheric methane budgets.

Tunable Diode Laser Atomic Absorption Spectroscopy for Detection of Potassium under Optically Thick Conditions.

PubMed

Qu, Zhechao; Steinvall, Erik; Ghorbani, Ramin; Schmidt, Florian M

2016-04-05

Potassium (K) is an important element related to ash and fine-particle formation in biomass combustion processes. In situ measurements of gaseous atomic potassium, K(g), using robust optical absorption techniques can provide valuable insight into the K chemistry. However, for typical parts per billion K(g) concentrations in biomass flames and reactor gases, the product of atomic line strength and absorption path length can give rise to such high absorbance that the sample becomes opaque around the transition line center. We present a tunable diode laser atomic absorption spectroscopy (TDLAAS) methodology that enables accurate, calibration-free species quantification even under optically thick conditions, given that Beer-Lambert's law is valid. Analyte concentration and collisional line shape broadening are simultaneously determined by a least-squares fit of simulated to measured absorption profiles. Method validation measurements of K(g) concentrations in saturated potassium hydroxide vapor in the temperature range 950-1200 K showed excellent agreement with equilibrium calculations, and a dynamic range from 40 pptv cm to 40 ppmv cm. The applicability of the compact TDLAAS sensor is demonstrated by real-time detection of K(g) concentrations close to biomass pellets during atmospheric combustion in a laboratory reactor.

National review of ambient air toxics observations.

PubMed

Strum, Madeleine; Scheffe, Richard

2016-02-01

Ambient air observations of hazardous air pollutant (HAPs), also known as air toxics, derived from routine monitoring networks operated by states, local agencies, and tribes (SLTs), are analyzed to characterize national concentrations and risk across the nation for a representative subset of the 187 designated HAPs. Observations from the National Air Toxics Trend Sites (NATTS) network of 27 stations located in most major urban areas of the contiguous United States have provided a consistent record of HAPs that have been identified as posing the greatest risk since 2003 and have also captured similar concentration patterns of nearly 300 sites operated by SLTs. Relatively high concentration volatile organic compounds (VOCs) such as benzene, formaldehyde, and toluene exhibit the highest annual average concentration levels, typically ranging from 1 to 5 µg/m(3). Halogenated (except for methylene chloride) and semivolatile organic compounds (SVOCs) and metals exhibit concentrations typically 2-3 orders of magnitude lower. Formaldehyde is the highest national risk driver based on estimated cancer risk and, nationally, has not exhibited significant changes in concentration, likely associated with the large pool of natural isoprene and formaldehyde emissions. Benzene, toluene, ethylbenzene, and 1,3-butadiene are ubiquitous VOC HAPs with large mobile source contributions that continue to exhibit declining concentrations over the last decade. Common chlorinated organic compounds such as ethylene dichloride and methylene chloride exhibit increasing concentrations. The variety of physical and chemical attributes and measurement technologies across 187 HAPs result in a broad range of method detection limits (MDLs) and cancer risk thresholds that challenge confidence in risk results for low concentration HAPs with MDLs near or greater than risk thresholds. From a national monitoring network perspective, the ability of the HAPs observational database to characterize the multiple pollutant and spatial scale patterns influencing exposure is severely limited and positioned to benefit by leveraging a variety of emerging measurement technologies. Ambient air toxics observation networks have limited ability to characterize the broad suite of hazardous air pollutants (HAPs) that affect exposures across multiple spatial scales. While our networks are best suited to capture major urban-scale signals of ubiquitous volatile organic compound HAPs, incorporation of sensing technologies that address regional and local-scale exposures should be pursued to address major gaps in spatial resolution. Caution should be exercised in interpreting HAPs observations based on data proximity to minimum detection limit and risk thresholds.

N2 Fluxes From Amazon Cropland Are a Significant Component of Watershed N Budgets.

NASA Astrophysics Data System (ADS)

Fox, R. J.; Neill, C.; Macedo, M.; Davidson, E. A.; Lefebvre, P.; Jankowski, K.; Maracahipes-Santos, L.

2017-12-01

Amazon tropical rainforests have experienced significant deforestation and conversion to cropland. Recently, cropping has intensified to include higher application rates of N fertilizer, typically in a soybean-corn rotation. Our previous work in Mato Grosso, Brazil, suggests that the addition of N fertilizer (80 Kg N ha-1 yr-1) has not increased N2O fluxes from soils or elevated dissolved N concentrations in streams or groundwater. Here, we investigate whether N fertilizer is converted to N2 in groundwater. We collected samples during January and October 2016 from streams and well transects across riparian forest buffers bordering cropland or within intact riparian forests. Samples were collected using a positive pressure pump and analyzed using Membrane Inlet Mass Spectrometry (MIMS) for N2, Ar, and O2 and gas chromatography for N2O and CH4. N2 concentrations in excess of solubility (based on Ar) were measured at nearly all locations in January and ranged from -15 to 220 in cropland and -2 to 93 µmol N2-N L-1 in intact forest. N2 concentrations were generally lower in October and ranged from -0.9 to 95 in cropland and -0.6 to 52 µmol N2-N L-1 in intact forest. Higher N2 concentrations accumulated at lower dissolved oxygen concentrations and at the borders between cropland and riparian forest. N2O concentrations were significantly lower than N2 concentrations on both dates and ranged between 0.01 and 0.33 µmol N2O-N L-1. Preliminary estimates suggest that N2 losses from cropland ranged from 10 to 20 kg N ha-1 y-1 and losses from forests ranged from 2 to 12 kg N ha-1 y-1. High concentrations of N2 in groundwater have been found in and around agricultural fields in temperate regions, but direct N2 measurements in tropical agricultural regions have not been previously documented. These results suggest that N2 fluxes from tropical cropland receiving modest amounts of N fertilizer could be substantial.

Analysis of the Effects of Cell Stress and Cytotoxicity on In ...

EPA Pesticide Factsheets

Chemical toxicity can arise from disruption of specific biomolecular functions or through more generalized cell stress and cytotoxicity-mediated processes. Here, concentration-dependent responses of 1063 chemicals including pharmaceuticals, natural products, pesticidals, consumer, and industrial chemicals across a diverse battery of 821 in vitro assay endpoints from 7 high-throughput assay technology platforms were analyzed in order to better distinguish between these types of activities. Both cell-based and cell-free assays showed a rapid increase in the frequency of responses at concentrations where cell stress / cytotoxicity responses were observed in cell-based assays. Chemicals that were positive on at least two viability/cytotoxicity assays within the concentration range tested (typically up to 100 M) activated a median of 12% of assay endpoints while those that were not cytotoxic in this concentration range activated 1.3% of the assays endpoints. The results suggest that activity can be broadly divided into: (1) specific biomolecular interactions against one or more targets (e.g., receptors or enzymes) at concentrations below which overt cytotoxicity-associated activity is observed; and (2) activity associated with cell stress or cytotoxicity, which may result from triggering of specific cell stress pathways, chemical reactivity, physico-chemical disruption of proteins or membranes, or broad low-affinity non-covalent interactions. Chemicals showing a g

Determination of 137Cs activity in soil from Qatar using high-resolution gamma-ray spectrometry

NASA Astrophysics Data System (ADS)

Al-Sulaiti, Huda; Nasir, Tabassum; Al Mugren, K. S.; Alkhomashi, N.; Al-Dahan, N.; Al-Dosari, M.; Bradley, D. A.; Bukhari, S.; Matthews, M.; Regan, P. H.; Santawamaitre, T.; Malain, D.; Habib, A.; Al-Dosari, Hanan; Al Sadig, Ibrahim; Daar, Eman

2016-10-01

With interest in establishing baseline concentrations of 137Cs in soil from the Qatarian peninsula, we focus on determination of the activity concentrations in 129 soil samples collected across the State of Qatar prior to the 2011 Fukushima Dai-ichi nuclear power plant accident. As such, the data provides the basis of a reference map for the detection of releases of this fission product. The activity concentrations were measured via high-resolution gamma-ray spectrometry using a hyper-pure germanium detector enclosed in a copper-lined passive lead shield that was situated in a low-background environment. The activity concentrations ranged from 0.21 to 15.41 Bq/kg, with a median value of 1 Bq/kg, the greatest activity concentration being observed in a sample obtained from northern Qatar. Although it cannot be confirmed, it is expected that this contamination is mainly due to releases from the Chernobyl accident of 26 April 1986, there being a lack of data from Qatar before the accident. The values are typically within but are sometimes lower than the range indicated by data from other countries in the region. The lower values than those of others is suggested to be due to variation in soil characteristics as well as metrological factors at the time of deposition.

Simulation of construction and demolition waste leachate

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

Townsend, T.G.; Jang, Y.; Thurn, L.G.

1999-11-01

Solid waste produced from construction and demolition (C and D) activities is typically disposed of in unlined landfills. Knowledge of C{ampersand}D debris landfill leachate is limited in comparison to other types of wastes. A laboratory study was performed to examine leachate resulting from simulated rainfall infiltrating a mixed C and D waste stream consisting of common construction materials (e.g., concrete, wood, drywall). Lysimeters (leaching columns) filled with the mixed C and D waste were operated under flooded and unsaturated conditions. Leachate constituent concentrations in the leachate from specific waste components were also examined. Leachate samples were collected and analyzed formore » a number of conventional water quality parameters including pH, alkalinity, total organic carbon, total dissolved solids, and sulfate. In experiments with the mixed C and D waste, high concentrations of total dissolved solids (TDS) and sulfate were detected in the leachate. C and D leachates produced as a result of unsaturated conditions exhibited TDS concentrations in the range of 570--2,200 mg/L. The major contributor to the TDS was sulfate, which ranged in concentration between 280 and 930 mg/L. The concentrations of sulfate in the leachate exceeded the sulfate secondary drinking water standard of 250 mg/L.« less

Nitrate in ground water and spring water near four dairy farms in North Florida, 1990-93

USGS Publications Warehouse

Andrews, W.J.

1994-01-01

Concentrations of nitrate and other selected water- quality characteristics were analyzed periodically for two years in water from 51 monitoring wells installed at four farms and in water discharging from three nearby springs along the Suwannee River in Lafayette and Suwannee Counties to examine the quality of ground water at these farms and the transport of nutrients in ground water to the nearby spring-fed Suwannee River: Ground water from shallow wells, which were completed in the top ten feet of the saturated zone in a surficial sandy aquifer and in the karstic Upper Floridan aquifer generally had the highest concentrations of nitrate, ranging from <.02 to 130 mg/L as nitrogen. Nitrate concentrations commonly exceeded the primary drinking water standard of 10 mg/L for nitrate as nitrogen in water from shallow wells, which tapped the top ten feet of the uppermost aquifers near waste-disposal areas such as wastewater lagoons and defoliated, intensive-use areas near milking barns. Upgradient from waste-disposal areas, concentrations of nitrate in ground water were commonly less than 1 mg/L as nitrogen. Water samples from deep wells (screened 20 feet deeper than shallow wells in these aquifers) generally had lower concentrations of nitrate (ranging from <0.02 to 84 mg/L) than water from shallow wells. Water samples from the three monitored springs (Blue, Telford, and Convict Springs) had nitrate concentrations ranging from 1.5 to 6.5 mg/L as nitrogen, which were higher than those typically occurring in water from upgradient wells at the monitored dairy farms or from back- ground wells sampled in the region. Analyses of nitrogen isotope ratios in nitrate indicated that leachate from animal wastes was the principal source of nitrate in ground water adjacent to waste-disposal areas at the monitored and unmonitored dairy farms. Leachate from a combi- nation of fertilizers, soils, and animal wastes appeared to be the source of nitrate in ground- water downgradient from pastures and wastewater spray fields at dairy farms and in water discharging from three nearby springs. Although denitrifying bacteria were present in counts sometimes exceeding 240,000 colonies/100mL in water from dairy-farm monitoring wells, ground water in the uppermost aquifers in Lafayette and Suwannee Counties generally contained too much oxygen for denitrification to remove nitrate from shallow ground water. Denitrification was more likely to occur in deeper ground water, which typically has lower dissolved oxygen concentrations.

Determination of dissolved methane in natural waters using headspace analysis with cavity ring-down spectroscopy.

PubMed

Roberts, Hannah M; Shiller, Alan M

2015-01-26

Methane (CH4) is the third most abundant greenhouse gas (GHG) but is vastly understudied in comparison to carbon dioxide. Sources and sinks to the atmosphere vary considerably in estimation, including sources such as fresh and marine water systems. A new method to determine dissolved methane concentrations in discrete water samples has been evaluated. By analyzing an equilibrated headspace using laser cavity ring-down spectroscopy (CRDS), low nanomolar dissolved methane concentrations can be determined with high reproducibility (i.e., 0.13 nM detection limit and typical 4% RSD). While CRDS instruments cost roughly twice that of gas chromatographs (GC) usually used for methane determination, the process presented herein is substantially simpler, faster, and requires fewer materials than GC methods. Typically, 70-mL water samples are equilibrated with an equivalent amount of zero air in plastic syringes. The equilibrated headspace is transferred to a clean, dry syringe and then drawn into a Picarro G2301 CRDS analyzer via the instrument's pump. We demonstrate that this instrument holds a linear calibration into the sub-ppmv methane concentration range and holds a stable calibration for at least two years. Application of the method to shipboard dissolved methane determination in the northern Gulf of Mexico as well as river water is shown. Concentrations spanning nearly six orders of magnitude have been determined with this method. Copyright © 2014 Elsevier B.V. All rights reserved.

Sensitivity of Cirrus Properties to Ice Nuclei Abundance

NASA Technical Reports Server (NTRS)

Jensen, Eric

2014-01-01

The relative importance of heterogeneous and homogeneous ice nucleation for cirrus formation remains an active area of debate in the cloud physics community. From a theoretical perspective, a number of modeling studies have investigated the sensitivity of ice number concentration to the nucleation mechanism and the abundance of ice nuclei. However, these studies typically only addressed ice concentration immediately after ice nucleation. Recent modeling work has shown that the high ice concentrations produced by homogeneous freezing may not persist very long, which is consistent with the low frequency of occurrence of high ice concentrations indicated by cirrus measurements. Here, I use idealized simulations to investigate the impact of ice nucleation mechanism and ice nuclei abundance on the full lifecycle of cirrus clouds. The primary modeling framework used includes different modes of ice nucleation, deposition growth/sublimation, aggregation, sedimentation, and radiation. A limited number of cloud-resolving simulations that treat radiation/dynamics interactions will also been presented. I will show that for typical synoptic situations with mesoscale waves present, the time-averaged cirrus ice crystal size distributions and bulk cloud properties are less sensitive to ice nucleation processes than might be expected from the earlier simple ice nucleation calculations. I will evaluate the magnitude of the ice nuclei impact on cirrus for a range of temperatures and mesoscale wave specifications, and I will discuss the implications for cirrus aerosol indirect effects in general.

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

Kzonski, J.; Lacombe, P.J.; Hochreiter, J.J.

Five former or active industrial or waste disposal sites in Logan Township were identified by the Federal government and by the State of New Jersey as potential threats to the quality of groundwater there. The sites are: (1) Air Products and Chemicals, Inc. waste disposal site; (2) Bridgeport Rental and Oil Services, Inc.; (3) Chemical Leaman Tank Lines, Inc.; (4) Monsanto Company; and (5) Rollins Environmental Services, Inc. Quality of groundwater was determined by chemical analysis of samples from wells at four of the five sites and elsewhere in the township. Groundwater in the lower aquifer of the Potomac-Raritan-magothy aquifermore » system in Logan Township and surrounding areas is dominated by sodium and chloride ions and is slightly saline. Calcium, sodium, and bicarbonate are the predominant ions in the upper and middle aquifers; the concentration of dissolved solids is low. Concentrations of iron and manganese in the groundwater range from 6 to 73,000 microgm/L, and from 33 to 1,100 microgm/L. Concentrations of organic carbon range from 0.60 to 4.2 mg/L. Areas of high apparent conductivity were detected east of the waste oil lagoon at the Bridgeport Rental and Oil Services, Inc. site. Inorganic groundwater contamination at the site is characterized by concentrations of cadmium and lead that exceed Federal and State primary drinking water regulations. Groundwater at the Chemical Leaman site also is characterized by elevated concentrations of organic nitrogen, and concentrations of As, Cr, Pb, and Hg that exceed Federal primary drinking water regulations. Concentrations of dissolved solids ranged from 339 to 3,530 mg/L at the Monsanto Site and typically are much higher than background levels, but the cause is unclear. 86 refs., 14 figs., 9 tabs.« less

Estimating Water Supply Arsenic Levels in the New England Bladder Cancer Study

PubMed Central

Freeman, Laura E. Beane; Lubin, Jay H.; Airola, Matthew S.; Baris, Dalsu; Ayotte, Joseph D.; Taylor, Anne; Paulu, Chris; Karagas, Margaret R.; Colt, Joanne; Ward, Mary H.; Huang, An-Tsun; Bress, William; Cherala, Sai; Silverman, Debra T.; Cantor, Kenneth P.

2011-01-01

Background: Ingestion of inorganic arsenic in drinking water is recognized as a cause of bladder cancer when levels are relatively high (≥ 150 µg/L). The epidemiologic evidence is less clear at the low-to-moderate concentrations typically observed in the United States. Accurate retrospective exposure assessment over a long time period is a major challenge in conducting epidemiologic studies of environmental factors and diseases with long latency, such as cancer. Objective: We estimated arsenic concentrations in the water supplies of 2,611 participants in a population-based case–control study in northern New England. Methods: Estimates covered the lifetimes of most study participants and were based on a combination of arsenic measurements at the homes of the participants and statistical modeling of arsenic concentrations in the water supply of both past and current homes. We assigned a residential water supply arsenic concentration for 165,138 (95%) of the total 173,361 lifetime exposure years (EYs) and a workplace water supply arsenic level for 85,195 EYs (86% of reported occupational years). Results: Three methods accounted for 93% of the residential estimates of arsenic concentration: direct measurement of water samples (27%; median, 0.3 µg/L; range, 0.1–11.5), statistical models of water utility measurement data (49%; median, 0.4 µg/L; range, 0.3–3.3), and statistical models of arsenic concentrations in wells using aquifers in New England (17%; median, 1.6 µg/L; range, 0.6–22.4). Conclusions: We used a different validation procedure for each of the three methods, and found our estimated levels to be comparable with available measured concentrations. This methodology allowed us to calculate potential drinking water exposure over long periods. PMID:21421449

Estimating water supply arsenic levels in the New England bladder cancer study

USGS Publications Warehouse

Nuckols, J.R.; Beane, Freeman L.E.; Lubin, J.H.; Airola, M.S.; Baris, D.; Ayotte, J.D.; Taylor, A.; Paulu, C.; Karagas, M.R.; Colt, J.; Ward, M.H.; Huang, A.-T.; Bress, W.; Cherala, S.; Silverman, D.T.; Cantor, K.P.

2011-01-01

Background: Ingestion of inorganic arsenic in drinking water is recognized as a cause of bladder cancer when levels are relatively high (??? 150 ??g/L). The epidemiologic evidence is less clear at the low-to-moderate concentrations typically observed in the United States. Accurate retrospective exposure assessment over a long time period is a major challenge in conducting epidemiologic studies of environmental factors and diseases with long latency, such as cancer. Objective: We estimated arsenic concentrations in the water supplies of 2,611 participants in a population-based case-control study in northern New England. Methods: Estimates covered the lifetimes of most study participants and were based on a combination of arsenic measurements at the homes of the participants and statistical modeling of arsenic concentrations in the water supply of both past and current homes. We assigned a residential water supply arsenic concentration for 165,138 (95%) of the total 173,361 lifetime exposure years (EYs) and a workplace water supply arsenic level for 85,195 EYs (86% of reported occupational years). Results: Three methods accounted for 93% of the residential estimates of arsenic concentration: direct measurement of water samples (27%; median, 0.3 ??g/L; range, 0.1-11.5), statistical models of water utility measurement data (49%; median, 0.4 ??g/L; range, 0.3-3.3), and statistical models of arsenic concentrations in wells using aquifers in New England (17%; median, 1.6 ??g/L; range, 0.6-22.4). Conclusions: We used a different validation procedure for each of the three methods, and found our estimated levels to be comparable with available measured concentrations. This methodology allowed us to calculate potential drinking water exposure over long periods.

Data and statistical summaries of background concentrations of metals in soils and streambed sediments in part of Big Soos Creek drainage basin, King County, Washington

USGS Publications Warehouse

Prych, E.A.; Kresch, D.L.; Ebbert, J.C.; Turney, G.L.

1995-01-01

Twenty-nine soil samples from 14 holes at 9 sites in part of the Big Soos Creek drainage basin in southwest King County, Washington, were collected and analyzed to obtain data on the magnitude and variability of background concentrations of metals in soils. Seven streambed-sediment samples and three streamwater samples from three sites also were collected and analyzed. These data are needed by regulating government agencies to determine if soils at sites of suspected contamination have elevated concentrations of metals, and to evaluate the effectiveness of remediation at sites with known contamination. Concentrations of 43 metals were determined by a total method, and concentrations of 17 metals were determined by a total-recoverable method and two different leaching methods. Metals analyzed for by all methods included most of those on the U.S. Environmental Protection agency list of priority pollutants, plus alluminum, iron, and manganese. Ranges of concentrations of metals determined by the total method are within ranges found by others for the conterminous United States. Concentrations of mercury, manganese, phosphorus, lead, selenium, antimony, and zinc as determined by the total method, and of some of these plus other metals as determined by the other methods were larger in shallow soil (less than 12 inches deep) than in deep soil (greater than 12 inches). Concentrations of metals in streambed sediments were more typical of shallow than deep soils.

Magnesium flux during continuous venovenous haemodiafiltration with heparin and citrate anticoagulation.

PubMed

Brain, Matthew; Anderson, Mike; Parkes, Scott; Fowler, Peter

2012-12-01

To describe magnesium flux and serum concentrations in ICU patients receiving continuous venovenous haemodiafiltration (CVVHDF). Samples were collected from 22 CVVHDF circuits using citrate anticoagulation solutions (Prismocitrate 10/2 and Prism0cal) and from 26 circuits using Hemosol B0 and heparin anticoagulation. CVVHDF prescription, magnesium supplementation and anticoagulation choice was by the treating intensivist. We analysed 334 sample sets consisting of arterial, prefilter and postfilter blood and effluent. Magnesium loss was calculated from an equation for conservation of mass, and arterial magnesium concentration was described by an equation for exponential decay. Using flow rates typical of adults receiving CVVHDF, we determined a median half-life for arterial magnesium concentration to decay to a new steady state of 4.73 hours (interquartile range [IQR], 3.73-7.32 hours). Median arterial magnesium concentration was 0.88mmol/L (IQR, 0.83-0.97mmol/L) in the heparin group and 0.79mmol/L (IQR, 0.69-0.91mmol/L) in the citrate group. Arterial magnesium concentrations fell below the reference range regularly in the citrate group and, when low, there was magnesium flux from dialysate to patient. Magnesium loss was greater in patients receiving citrate. Exponential decline in magnesium concentrations was sufficiently rapid that subtherapeutic serum magnesium concentrations may occur well before detection when once-daily sampling was used. Measurements should be interpreted with regard to timing of magnesium infusions. We suggest that continuous renal replacement therapy fluids with higher magnesium concentrations be introduced in the critical care setting.

Airborne endotoxin in fine particulate matter in Beijing

NASA Astrophysics Data System (ADS)

Guan, Tianjia; Yao, Maosheng; Wang, Junxia; Fang, Yanhua; Hu, Songhe; Wang, Yan; Dutta, Anindita; Yang, Junnan; Wu, Yusheng; Hu, Min; Zhu, Tong

2014-11-01

Endotoxin is an important biological component of particulate matter (PM) which, upon inhalation, can induce adverse health effects, and also possibly complicate the diseases in combination with other pollutants. From 1 March 2012 to 27 February 2013 we collected air samples using quartz filters daily for the quantification of airborne endotoxin and also fine PM (PM2.5) in Beijing, China. The geometric means for endotoxin concentration and the fraction of endotoxin in PM were 0.65 EU/m3 (range: 0.10-75.02) and 10.25 EU/mg PM2.5 (range: 0.38-1627.29), respectively. The endotoxin concentrations were shown to vary greatly with seasons, typically with high values in the spring and winter seasons. Temperature and relative humidity, as well as concentrations of sulfur dioxide and nitrogen oxides were found to be significantly correlated with airborne endotoxin concentrations (p < 0.05). Additionally, positive correlations were also detected between endotoxin concentrations and natural sources of Na+, K+, Mg2+, and F-, while negative correlations were observed between endotoxin concentrations and anthropogenic sources of P, Co, Zn, As, and Tl. Oxidative potential analysis revealed that endotoxin concentrations were positively correlated with reactive oxygen species (ROS), but not dithiothreitol (DTT) of PM. This study provided the first continuous time series of airborne endotoxin concentrations in Beijing, and identifies its potential associations with atmospheric factors. The information developed here can assist in the assessment of health effects of air pollution in Beijing.

Assessment of Occupational Exposure to Bisphenol A in Five Different Production Companies in Finland.

PubMed

Heinälä, Milla; Ylinen, Katriina; Tuomi, Tapani; Santonen, Tiina; Porras, Simo P

2017-01-01

The aim of the study was to assess occupational exposure to bisphenol A in Finland. Five companies took part in the research project: two paint factories (liquid and powder paints), a composite product factory, a thermal paper factory, and a tractor factory. Exposure was assessed by measuring total bisphenol A excretion (free and conjugated) from urine samples, and its concentrations in the air. The results revealed the specific work tasks in two of five companies in which significant occupational exposure to bisphenol A may occur. In the manufacturing of liquid paint hardener, urine samples collected after the working day showed bisphenol A levels of up to 100-170 µg l-1. Workers in thermal paper manufacturing were also exposed to bisphenol A, especially those working in the manufacture of coating material and operating coating machines. Median concentrations of the post-shift urine samples of coating machine workers were in the range of 130-250 µg l-1. The highest bisphenol A concentrations were in the range of 1000-1500 µg l-1. Recommendations for more effective personal protection resulted in decreased exposure, particularly among coating machine operators. In the rest of the companies, urinary bisphenol A levels were typically in the range of those of the general population. Bisphenol A concentrations in air samples were typically low (<40 µg m-3), except in some short-term duties related to the handling of solid bisphenol A (maximum 17.6 mg m-3). Low air levels, even in the companies with high urinary levels, suggest exposure via dermal contact. According to the results, exposure to bisphenol A may occur particularly in work tasks that involve the use of pure bisphenol A. In these tasks, special attention should be paid to the prevention of skin exposure. Inhalation exposure may become relevant in dusty work tasks. Since skin exposure is of potential concern in these tasks, biomonitoring is recommended as the method for assessing occupational exposure to bisphenol A. © The Author 2017. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

[Distribution characteristics of organochlorine pesticides in soil from Daiyun Mountain Range in Fujian, China].

PubMed

Qu, Cheng-Kai; Qi, Shi-Hua; Zhang, Li; Huang, Huan-Fang; Zhang, Jia-Quan; Zhang, Yuan; Yang, Dan; Liu, Hong-Xia; Chen, Wei

2013-11-01

Totally 101 typical surface soil samples were collected from Daiyun Mountain Range, and 20 compounds of OCPs were analyzed by a Ni electron capture detector (GC-ECD) to investigate the horizontal distribution and composition of organochlorine pesticides (OCPs) in the surface soil of Daiyun Mountain Range. The results showed that all OCPs were detected in the soil samples. The detection ratios of OCPs were all over 90%, except for Endrin and beta-HCH. The sum concentration of HCHs, DDTs, Endosulfan and Endosulfan sulfate, accounted for 79.51% of the total OCPs, which were considered to be the dominant OCPs in the Daiyun Mountain Range. The OCPs concentrations in the surface soils ranged from 2.56 to 465.99 ng x g(-1) with a mean value of 38.00 ng x g)(-1). Compared with other regions, the concentrations of HCHs and DDTs in this study stayed in a low pollution level. Endosulfan and Endosulfan sulfate showed a certain degree of risk in the surface soil of the study area. Source analysis showed that new input of lindane and dicofol might occur in the survey region. The historical application was the prime source of Endosulfan. The residue level of OCPs in different lands was in the following order: paddy land > vegetable land > orchard. The OCPs pollution of orchard soil was primarily due to the new input of lindane and dicofol, while the pollution of paddy land was mainly from the usage of Endosulfan.

Natural radioactivity and radon exhalation rates in man-made tiles used as building materials in Japan.

PubMed

Iwaoka, K; Hosoda, M; Suwankot, N; Omori, Y; Ishikawa, T; Yonehara, H; Tokonami, S

2015-11-01

Man-made tiles frequently used in Japan were collected, and activity concentrations and radon ((222)Rn) exhalation rates in these tiles were measured. Dose estimations for inhabitants living in houses built using these tiles were also carried out. The activity concentrations of (226)Ra, (228)Ra and (40)K in the man-made tiles were 31-170, 35-110 and 260-980 Bq kg(-1), respectively. The (222)Rn exhalation rates in the tiles were 8.8-21 μBq m(-2) s(-1). The ranges of experimental activity concentrations and (222)Rn exhalation rates were almost identical to those of natural rocks used as typical building materials in Japan. The maximum value of effective dose to inhabitants living in houses built with the man-made tiles was 0.14 mSv y(-1), which is lower than the reference level range (1-20 mSv y(-1)) for abnormally high levels of natural background radiation published in the ICRP Publication 103. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Biological nitrification/denitrification of high sodium nitrite (navy shipyard) wastewater.

PubMed

Kamath, S; Sabatini, D A; Canter, L W

1991-01-01

In the hydroblasting of ships' boiler tubes, a wastewater high in nitrite (as high as 1200 mg litre(-1)) is produced by the US Navy. This research has evaluated the use of a suspended-growth biological system to treat this wastewater by denitrification. Two biological treatment configurations were evaluated (direct denitrification versus nitrification/denitrification) with nitrification/denitrification producing better nitrite removal efficiencies (54 to 62% versus 40%, respectively). The introduction of metals (cadmium, chromium, lead, copper and iron) in concentrations typical for this wastewater did not inhibit the nitrite removal efficiencies. The influent metal concentrations ranged from 0.02 mg litre(-1) for cadmium to 22 mg litre(-1) for iron and the metal removal efficiencies ranged from 4.8% for cadmium to 50% for copper. Increasing sludge age resulted in improved nitrite removal efficiencies (52%, 57% and 74% for sludge ages of 4, 6 and 8 days, respectively). The resulting biokinetic constants were similar to those reported by others for lower influent concentrations of nitrite or nitrate (Ygs=0.02 mg/mg; Ygn=0.16 mg/mg; Yb=0.8 mg/mg; and b=0.006 h(-1)).

An international marine-atmospheric {sup 222}Rn measurement intercomparison in Bermuda. Part 1: NIST calibration and methodology for standardized sample additions

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

Colle, R.; Unterweger, M.P.; Hodge, P.A.

1996-01-01

As part of an international {sup 222}Rn measurement intercomparison conducted at Bermuda in October 1991, NIST provided standardized sample additions of known, but undisclosed (blind) {sup 222}Rn concentrations that could be related to US national standards. The standardized sample additions were obtained with a calibrated {sup 226}Ra source and a specially-designed manifold used to obtain well-known dilution factors from simultaneous flow-rate measurements. The additions were introduced over sampling periods of several hours (typically 4 h) into a common streamline on a sampling tower used by the participating laboratories for their measurements. The standardized {sup 222}Rn activity concentrations for the intercomparisonmore » ranged from approximately 2.5 Bq {center_dot} m{sup {minus}3} to 35 Bq {center_dot} m{sup {minus}3} (of which the lower end of this range approached concentration levels for ambient Bermudian air) and had overall uncertainties, approximating a 3 standard deviation uncertainty interval, of about 6% to 13%. This paper describes the calibration and methodology for the standardized sample additions.« less

An International Marine-Atmospheric 222Rn Measurement Intercomparison in Bermuda Part I: NIST Calibration and Methodology for Standardized Sample Additions

PubMed Central

Collé, R.; Unterweger, M. P.; Hodge, P. A.; Hutchinson, J. M. R.

1996-01-01

As part of an international 222Rn measurement intercomparison conducted at Bermuda in October 1991, NIST provided standardized sample additions of known, but undisclosed (“blind”) 222Rn concentrations that could be related to U.S. national standards. The standardized sample additions were obtained with a calibrated 226Ra source and a specially-designed manifold used to obtain well-known dilution factors from simultaneous flow-rate measurements. The additions were introduced over sampling periods of several hours (typically 4 h) into a common streamline on a sampling tower used by the participating laboratories for their measurements. The standardized 222Rn activity concentrations for the intercomparison ranged from approximately 2.5 Bq · m−3 to 35 Bq · m−3 (of which the lower end of this range approached concentration levels for ambient Bermudian air) and had overall uncertainties, approximating a 3 standard deviation uncertainty interval, of about 6 % to 13 %. This paper describes the calibration and methodology for the standardized sample additions. PMID:27805090

PM2.5, PM10 and health risk assessment of heavy metals in a typical printed circuit noards manufacturing workshop.

PubMed

Zhou, Peng; Guo, Jie; Zhou, Xiaoyu; Zhang, Wei; Liu, Lili; Liu, Yangcheng; Lin, Kuangfei

2014-10-01

A typical Printed Circuit Board (PCB) manufacturer was chosen as the object of this study. During PCB processing, fine particulate matter and heavy metals (Cu, Zn, Pb, Cr, Cd and Ni) will be released into the air and dust, which then impact workers' health and the environment. The concentrations of total suspended particle (TSP), PM10 and PM2.5 in the off-site were 106.3, 90.0 and 50.2μg/m(3), respectively, while the concentrations of TSP, PM10 and PM2.5 in the workshops ranged from 36.1 to 365.3, from 27.1 to 289.8 and from 22.1 to 212.3μg/m(3), respectively. Almost all six of the heavy metals were detected in all of the particle samples except Cd. For each workshop, it was obvious that Zn was the most enriched metal in TSP, followed by Cu>Pb (Cr)>Ni>Cd, and the same trend was found for PM10 and PM2.5. In the dust samples, Cu (which ranged from 4.02 to 56.31mg/g) was the most enriched metal, followed by Zn, Cr, Pb, Ni and Cd, and the corresponding concentrations ranged from 0.77 to 4.47, 0.37 to 1.59, 0.26 to 0.84, 0.13 to 0.44 and nd to 0.078mg/g, respectively. The health risk assessment showed that noncancerous effects are unlikely for Zn, Pb, Cr, Cu, Cd and Ni. The carcinogenic risks for Cd and Ni were all lower than 10(-6), except for Cr. This result indicates that carcinogenic risks for workers are relatively possible in the workshops. These findings suggest that this technology is advanced from the perspective of environmental protection in the waste PCB's recycling industry. Copyright © 2014. Published by Elsevier B.V.

Erratum: Probabilistic application of a fugacity model to predict triclosan fate during wastewater treatment.

PubMed

Bock, Michael; Lyndall, Jennifer; Barber, Timothy; Fuchsman, Phyllis; Perruchon, Elyse; Capdevielle, Marie

2010-10-01

The fate and partitioning of the antimicrobial compound, triclosan, in wastewater treatment plants (WWTPs) is evaluated using a probabilistic fugacity model to predict the range of triclosan concentrations in effluent and secondary biosolids. The WWTP model predicts 84% to 92% triclosan removal, which is within the range of measured removal efficiencies (typically 70% to 98%). Triclosan is predominantly removed by sorption and subsequent settling of organic particulates during primary treatment and by aerobic biodegradation during secondary treatment. Median modeled removal efficiency due to sorption is 40% for all treatment phases and 31% in the primary treatment phase. Median modeled removal efficiency due to biodegradation is 48% for all treatment phases and 44% in the secondary treatment phase. Important factors contributing to variation in predicted triclosan concentrations in effluent and biosolids include influent concentrations, solids concentrations in settling tanks, and factors related to solids retention time. Measured triclosan concentrations in biosolids and non-United States (US) effluent are consistent with model predictions. However, median concentrations in US effluent are over-predicted with this model, suggesting that differences in some aspect of treatment practices not incorporated in the model (e.g., disinfection methods) may affect triclosan removal from effluent. Model applications include predicting changes in environmental loadings associated with new triclosan applications and supporting risk analyses for biosolids-amended land and effluent receiving waters. © 2010 SETAC.

Probabilistic application of a fugacity model to predict triclosan fate during wastewater treatment.

PubMed

Bock, Michael; Lyndall, Jennifer; Barber, Timothy; Fuchsman, Phyllis; Perruchon, Elyse; Capdevielle, Marie

2010-07-01

The fate and partitioning of the antimicrobial compound, triclosan, in wastewater treatment plants (WWTPs) is evaluated using a probabilistic fugacity model to predict the range of triclosan concentrations in effluent and secondary biosolids. The WWTP model predicts 84% to 92% triclosan removal, which is within the range of measured removal efficiencies (typically 70% to 98%). Triclosan is predominantly removed by sorption and subsequent settling of organic particulates during primary treatment and by aerobic biodegradation during secondary treatment. Median modeled removal efficiency due to sorption is 40% for all treatment phases and 31% in the primary treatment phase. Median modeled removal efficiency due to biodegradation is 48% for all treatment phases and 44% in the secondary treatment phase. Important factors contributing to variation in predicted triclosan concentrations in effluent and biosolids include influent concentrations, solids concentrations in settling tanks, and factors related to solids retention time. Measured triclosan concentrations in biosolids and non-United States (US) effluent are consistent with model predictions. However, median concentrations in US effluent are over-predicted with this model, suggesting that differences in some aspect of treatment practices not incorporated in the model (e.g., disinfection methods) may affect triclosan removal from effluent. Model applications include predicting changes in environmental loadings associated with new triclosan applications and supporting risk analyses for biosolids-amended land and effluent receiving waters. (c) 2010 SETAC.

Effects of wind direction on coarse and fine particulate matter concentrations in southeast Kansas.

PubMed

Guerra, Sergio A; Lane, Dennis D; Marotz, Glen A; Carter, Ray E; Hohl, Carrie M; Baldauf, Richard W

2006-11-01

Field data for coarse particulate matter ([PM] PM10) and fine particulate matter (PM2.5) were collected at selected sites in Southeast Kansas from March 1999 to October 2000, using portable MiniVol particulate samplers. The purpose was to assess the influence on air quality of four industrial facilities that burn hazardous waste in the area located in the communities of Chanute, Independence, Fredonia, and Coffeyville. Both spatial and temporal variation were observed in the data. Variation because of sampling site was found to be statistically significant for PM10 but not for PM2.5. PM10 concentrations were typically slightly higher at sites located within the four study communities than at background sites. Sampling sites were located north and south of the four targeted sources to provide upwind and downwind monitoring pairs. No statistically significant differences were found between upwind and downwind samples for either PM10 or PM2.5, indicating that the targeted sources did not contribute significantly to PM concentrations. Wind direction can frequently contribute to temporal variation in air pollutant concentrations and was investigated in this study. Sampling days were divided into four classifications: predominantly south winds, predominantly north winds, calm/variable winds, and winds from other directions. The effect of wind direction was found to be statistically significant for both PM10 and PM2.5. For both size ranges, PM concentrations were typically highest on days with predominantly south winds; days with calm/variable winds generally produced higher concentrations than did those with predominantly north winds or those with winds from "other" directions. The significant effect of wind direction suggests that regional sources may exert a large influence on PM concentrations in the area.

RWPV bioreactor mass transport: earth-based and in microgravity

NASA Technical Reports Server (NTRS)

Begley, Cynthia M.; Kleis, Stanley J.

2002-01-01

Mass transport and mixing of perfused scalar quantities in the NASA Rotating Wall Perfused Vessel bioreactor are studied using numerical models of the flow field and scalar concentration field. Operating conditions typical of both microgravity and ground-based cell cultures are studied to determine the expected vessel performance for both flight and ground-based control experiments. Results are presented for the transport of oxygen with cell densities and consumption rates typical of colon cancer cells cultured in the RWPV. The transport and mixing characteristics are first investigated with a step change in the perfusion inlet concentration by computing the time histories of the time to exceed 10% inlet concentration. The effects of a uniform cell utilization rate are then investigated with time histories of the outlet concentration, volume average concentration, and volume fraction starved. It is found that the operating conditions used in microgravity produce results that are quite different then those for ground-based conditions. Mixing times for microgravity conditions are significantly shorter than those for ground-based operation. Increasing the differential rotation rates (microgravity) increases the mixing and transport, while increasing the mean rotation rate (ground-based) suppresses both. Increasing perfusion rates enhances mass transport for both microgravity and ground-based cases, however, for the present range of operating conditions, above 5-10 cc/min there are diminishing returns as much of the inlet fluid is transported directly to the perfusion exit. The results show that exit concentration is not a good indicator of the concentration distributions in the vessel. In microgravity conditions, the NASA RWPV bioreactor with the viscous pump has been shown to provide an environment that is well mixed. Even when operated near the theoretical minimum perfusion rates, only a small fraction of the volume provides less than the required oxygen levels. 2002 Wiley Periodicals, Inc.

RWPV bioreactor mass transport: earth-based and in microgravity.

PubMed

Begley, Cynthia M; Kleis, Stanley J

2002-11-20

Mass transport and mixing of perfused scalar quantities in the NASA Rotating Wall Perfused Vessel bioreactor are studied using numerical models of the flow field and scalar concentration field. Operating conditions typical of both microgravity and ground-based cell cultures are studied to determine the expected vessel performance for both flight and ground-based control experiments. Results are presented for the transport of oxygen with cell densities and consumption rates typical of colon cancer cells cultured in the RWPV. The transport and mixing characteristics are first investigated with a step change in the perfusion inlet concentration by computing the time histories of the time to exceed 10% inlet concentration. The effects of a uniform cell utilization rate are then investigated with time histories of the outlet concentration, volume average concentration, and volume fraction starved. It is found that the operating conditions used in microgravity produce results that are quite different then those for ground-based conditions. Mixing times for microgravity conditions are significantly shorter than those for ground-based operation. Increasing the differential rotation rates (microgravity) increases the mixing and transport, while increasing the mean rotation rate (ground-based) suppresses both. Increasing perfusion rates enhances mass transport for both microgravity and ground-based cases, however, for the present range of operating conditions, above 5-10 cc/min there are diminishing returns as much of the inlet fluid is transported directly to the perfusion exit. The results show that exit concentration is not a good indicator of the concentration distributions in the vessel. In microgravity conditions, the NASA RWPV bioreactor with the viscous pump has been shown to provide an environment that is well mixed. Even when operated near the theoretical minimum perfusion rates, only a small fraction of the volume provides less than the required oxygen levels. 2002 Wiley Periodicals, Inc.

Concentrations of cadmium, Cobalt, Lead, Nickel, and Zinc in Blood and Fillets of Northern Hog Sucker (Hypentelium nigricans) from streams contaminated by lead-Zinc mining: Implications for monitoring

USGS Publications Warehouse

Schmitt, C.J.; Brumbaugh, W.G.; May, T.W.

2009-01-01

Lead (Pb) and other metals can accumulate in northern hog sucker (Hypentelium nigricans) and other suckers (Catostomidae), which are harvested in large numbers from Ozark streams by recreational fishers. Suckers are also important in the diets of piscivorous wildlife and fishes. Suckers from streams contaminated by historic Pb-zinc (Zn) mining in southeastern Missouri are presently identified in a consumption advisory because of Pb concentrations. We evaluated blood sampling as a potentially nonlethal alternative to fillet sampling for Pb and other metals in northern hog sucker. Scaled, skin-on, bone-in "fillet" and blood samples were obtained from northern hog suckers (n = 75) collected at nine sites representing a wide range of conditions relative to Pb-Zn mining in southeastern Missouri. All samples were analyzed for cadmium (Cd), cobalt (Co), Pb, nickel (Ni), and Zn. Fillets were also analyzed for calcium as an indicator of the amount of bone, skin, and mucus included in the samples. Pb, Cd, Co, and Ni concentrations were typically higher in blood than in fillets, but Zn concentrations were similar in both sample types. Concentrations of all metals except Zn were typically higher at sites located downstream from active and historic Pb-Zn mines and related facilities than at nonmining sites. Blood concentrations of Pb, Cd, and Co were highly correlated with corresponding fillet concentrations; log-log linear regressions between concentrations in the two sample types explained 94% of the variation for Pb, 73-83% of the variation for Co, and 61% of the variation for Cd. In contrast, relations for Ni and Zn explained <12% of the total variation. Fillet Pb and calcium concentrations were correlated (r = 0.83), but only in the 12 fish from the most contaminated site; concentrations were not significantly correlated across all sites. Conversely, fillet Cd and calcium were correlated across the range of sites (r = 0.78), and the inclusion of calcium in the fillet-to-blood relation explained an additional 12% of the total variation in fillet Cd. Collectively, the results indicate that blood sampling could provide reasonably accurate and precise estimates of fillet Pb, Co, and Cd concentrations that would be suitable for identifying contaminated sites and for monitoring, but some fillet sampling might be necessary at contaminated sites for establishing consumption advisories. ?? 2009 US Government.

Add-on lacosamide: a retrospective study on the relationship between serum concentration, dosage, and adverse events.

PubMed

Hillenbrand, Barbara; Wisniewski, Ilona; Jürges, Uta; Steinhoff, Bernhard J

2011-11-01

We performed a retrospective study in patients with poorly controlled epilepsy treated with add-on lacosamide (LCM) to investigate the relationship of LCM-related adverse events with LCM serum concentration and weight-dependent dosage. We collected serum concentrations, weight-related dosages, and occurrences of the seven most frequent adverse events according to the randomized double-blind, placebo-controlled trials. Seventy of 131 patients could be sufficiently evaluated. LCM serum concentrations and weight-related dosages in patients with and without typical adverse events did not differ significantly. Closer analysis of the data suggested that dizziness as the leading adverse event occurred significantly more often if LCM was combined with classic sodium channel blockers. There was a significant correlation between LCM serum concentrations and co-medication, so there is still evidence for dependent variables that might have a relevant impact in individual cases. However, our data do not allow definition of a safety range for LCM. Copyright © 2011 Elsevier Inc. All rights reserved.

Hydrodynamic study of an internal airlift reactor for microalgae culture.

PubMed

Rengel, Ana; Zoughaib, Assaad; Dron, Dominique; Clodic, Denis

2012-01-01

Internal airlift reactors are closed systems considered today for microalgae cultivation. Several works have studied their hydrodynamics but based on important solid concentrations, not with biomass concentrations usually found in microalgae cultures. In this study, an internal airlift reactor has been built and tested in order to clarify the hydrodynamics of this system, based on microalgae typical concentrations. A model is proposed taking into account the variation of air bubble velocity according to volumetric air flow rate injected into the system. A relationship between riser and downcomer gas holdups is established, which varied slightly with solids concentrations. The repartition of solids along the reactor resulted to be homogenous for the range of concentrations and volumetric air flow rate studied here. Liquid velocities increase with volumetric air flow rate, and they vary slightly when solids are added to the system. Finally, liquid circulation time found in each section of the reactor is in concordance with those employed in microalgae culture.

Design of light concentrators for Cherenkov telescope observatories

NASA Astrophysics Data System (ADS)

Hénault, François; Petrucci, Pierre-Olivier; Jocou, Laurent; Khélifi, Bruno; Manigot, Pascal; Hormigos, Stéphane; Knödlseder, Jürgen; Olive, Jean-François; Jean, Pierre; Punch, Michael

2013-09-01

The Cherenkov Telescope Array (CTA) will be the largest cosmic gamma ray detector ever built in the world. It will be installed at two different sites in the North and South hemispheres and should be operational for about 30 years. In order to cover the desired energy range, the CTA is composed of typically 50-100 collecting telescopes of various sizes (from 6 to 24-m diameters). Most of them are equipped with a focal plane camera consisting of 1500 to 2000 Photomultipliers (PM) equipped with light concentrating optics, whose double function is to maximize the amount of Cherenkov light detected by the photo-sensors, and to block any stray light originating from the terrestrial environment. Two different optical solutions have been designed, respectively based on a Compound Parabolic Concentrator (CPC), and on a purely dioptric concentrating lens. In this communication are described the technical specifications, optical designs and performance of the different solutions envisioned for all these light concentrators. The current status of their prototyping activities is also given.

Dissolved methane concentrations in the water column and surface sediments of Hanna Shoal and Barrow Canyon, Northern Chukchi Sea

NASA Astrophysics Data System (ADS)

Lapham, Laura; Marshall, Kathleen; Magen, Cédric; Lyubchich, Viacheslav; Cooper, Lee W.; Grebmeier, Jacqueline M.

2017-10-01

Current estimates of methane (CH4) flux suggest that Arctic shelves may be a significant source of atmospheric CH4, a potent greenhouse gas. However, little information is known about the CH4 flux from most Arctic shelves, other than the East Siberian Arctic Shelf. We report here dissolved CH4 concentrations in the water column and within surface sediments of the Northern Chukchi Sea. We hypothesized that this area contains high concentrations of CH4 because it receives nutrient rich waters through the Bering Strait, promoting primary production that enhances an organic-rich material flux to the seafloor and eventual microbial methanogenesis in the sediments. In August 2012, as part of the Chukchi Sea Offshore Monitoring in Drilling Area (COMIDA) project, fourteen stations were sampled on Hanna Shoal, a shallow feature on the shelf, and ten stations across the undersea Barrow Canyon. On Hanna Shoal, water column CH4 concentrations ranged from 14 to 74 nM, and surface concentrations were up to 15 times supersaturated in CH4 compared to equilibrium with the average atmospheric concentrations (3 nM). CH4 concentrations at the sediment-water interface were around 1,500 nM, and typically increased with depth in the sediment. At the head of Barrow Canyon, water column CH4 concentrations ranged from 5 to 46 nM, with the highest concentrations in the deepest waters that were sampled (118 m). Overall, the calculated fluxes to the atmosphere ranged from 1 to 80 μmol CH4 m-2 d-1 for Hanna Shoal and 4 to 17 μmol CH4 m-2 d-1 across the Barrow Canyon stations. Although there was a large range in these fluxes, the average atmospheric flux (20 μmol CH4 m-2 d-1) across Hanna Shoal was 12 times lower than the flux reported from the East Siberian Arctic Shelf in summer. We conclude that while there is a positive flux of CH4 to the atmosphere, this part of the Chukchi Sea is not a significant source of atmospheric CH4 compared to the East Siberian Sea shelf.

Optimal estimation of suspended-sediment concentrations in streams

USGS Publications Warehouse

Holtschlag, D.J.

2001-01-01

Optimal estimators are developed for computation of suspended-sediment concentrations in streams. The estimators are a function of parameters, computed by use of generalized least squares, which simultaneously account for effects of streamflow, seasonal variations in average sediment concentrations, a dynamic error component, and the uncertainty in concentration measurements. The parameters are used in a Kalman filter for on-line estimation and an associated smoother for off-line estimation of suspended-sediment concentrations. The accuracies of the optimal estimators are compared with alternative time-averaging interpolators and flow-weighting regression estimators by use of long-term daily-mean suspended-sediment concentration and streamflow data from 10 sites within the United States. For sampling intervals from 3 to 48 days, the standard errors of on-line and off-line optimal estimators ranged from 52.7 to 107%, and from 39.5 to 93.0%, respectively. The corresponding standard errors of linear and cubic-spline interpolators ranged from 48.8 to 158%, and from 50.6 to 176%, respectively. The standard errors of simple and multiple regression estimators, which did not vary with the sampling interval, were 124 and 105%, respectively. Thus, the optimal off-line estimator (Kalman smoother) had the lowest error characteristics of those evaluated. Because suspended-sediment concentrations are typically measured at less than 3-day intervals, use of optimal estimators will likely result in significant improvements in the accuracy of continuous suspended-sediment concentration records. Additional research on the integration of direct suspended-sediment concentration measurements and optimal estimators applied at hourly or shorter intervals is needed.

The influence of environmental factors on the deposition velocity of thoron progeny.

PubMed

Li, H; Zhang, L; Guo, Q

2012-11-01

Passive measuring devices are comprehensively employed in thoron progeny surveys, while the deposition velocity of thoron progeny is the most critical parameter, which varies in different environments. In this study, to analyse the influence of environmental factors on thoron progeny deposition velocity, an improved model was proposed on the basis of Lai's aerosol deposition model and the Jacobi's model, and a series of measurements were carried out to verify the model. According to the calculations, deposition velocity decreases with increasing aerosol diameter and also aerosol concentration, while increases with increasing ventilation rate. In typical indoor environments, a typical value of 1.26 × 10(-5)m s(-1) is recommended, with a range between 7.6 × 10(-7) and 3.2 × 10(-4) m s(-1).

Cost/performance of solar reflective surfaces for parabolic dish concentrators

NASA Technical Reports Server (NTRS)

Bouquet, F.

1980-01-01

Materials for highly reflective surfaces for use in parabolic dish solar concentrators are discussed. Some important factors concerning performance of the mirrors are summarized, and typical costs are treated briefly. Capital investment cost/performance ratios for various materials are computed specifically for the double curvature parabolic concentrators using a mathematical model. The results are given in terms of initial investment cost for reflective surfaces per thermal kilowatt delivered to the receiver cavity for various operating temperatures from 400 to 1400 C. Although second surface glass mirrors are emphasized, first surface, chemically brightened and anodized aluminum surfaces as well as second surface, metallized polymeric films are treated. Conventional glass mirrors have the lowest cost/performance ratios, followed closely by aluminum reflectors. Ranges in the data due to uncertainties in cost and mirror reflectance factors are given.

Evaluation of data from the Vaisala CT25K for Estimation of PM10 Concentration and Mixing Heights in an Urban Environment

NASA Astrophysics Data System (ADS)

Gunter, R. L.; Hosker, R. P.

2005-12-01

During the month of August, the Urban Dispersion Project was conducted in New York City. NOAA's Atmospheric and Turbulence Division (ATDD), Oak Ridge, TN operated a Vaisala CT25K Ceilometer for a two-week timeframe during the project. Typically, ceilometer measurements are used for cloud height determination. It has been found that during dry conditions, there is a good correlation between the ceilometer near- range backscatter and in situ PM10 concentration readings. In addition, it also has been determined that the ceilometer is a suitable instrument for determining the convective mixing height (MH). Aerosol concentrations are calculated and mixing heights are estimated using data from the ceilometer during dry conditions in Manhattan. Mixing heights are compared to radiosonde data taken during the project.

Overview of the limnology of crater lake

USGS Publications Warehouse

Larson, G.L.

1996-01-01

Crater Lake occupies the collapsed caldera of volcanic Mount Mazama in Crater Lake National Park, Oregon. It is the deepest lake (589 m) in the United States and the 7th deepest lake in the world. The water column mixes to a depth of about 200 m in winter and spring from wind energy and cooling. The deep lake is mixed in winter and early spring each year when relatively cold water near the surface sinks and exchanges positions with water in the deep basins of the lake. The lake becomes thermally stratified in summer and early fall. The metalimnion extends to a depth of about 100 m; thus most of the water column is a cold hypolimnion. Secchi disk clarity measurements typically are in the upper-20-m range to the low-30-m range in summer and early fall. Concentrations of nutrients are low, although conductivity is relatively high owing to the inflow of hydrothermal fluids. Total chlorophyll is low in concentration, but typically maximal at a depth of 120 m during periods of thermal stratification. Primary production also is low, with the maximum levels occurring between the depth of 40 and 80 m. Phytoplankton taxa are spatially segregated from each other within the water column to a depth of 200 m in summer and early fall. The same generalization applies to the Zooplankton taxa. Water level, clarity, concentrations of total chlorophyll, primary production, and abundances of zooplankton and introduced kokanee salmon exhibit long-term fluctuations. Based primarily on a recent 10-year study of the lake, the lake is considered to be pristine, except for the consequences of fish introductions. ?? 1996 by the Northwest Scientific Association. All rights reserved.

Overview of the limnology of Crater Lake

USGS Publications Warehouse

Larson, Gary L.

1996-01-01

Crater Lake occupies the collapsed caldera of volcanic Mount Mazama in Crater Lake National Park, Oregon. It is the deepest lake (589 m) in the United States and the 7th deepest lake in the world. The water column mixes to a depth of about 200 m in winter and spring from wind energy and cooling. The deep lake is mixed in winter and early spring each year when relatively cold water near the surface sinks and exchanges positions with water in the deep basins of the lake. The lake becomes thermally stratified in summer and early fall. The metalimnion extends to a depth of about 100 m; thus most of the water column is a cold hypolimnion. Secchi disk clarity measurements typically are in the upper-20-m range to the low-30-m range in summer and early fall. Concentrations of nutrients are low, although conductivity is relatively high owing to the inflow of hydrothermal fluids. Total chlorophyll is low in concentration, but typically maximal at a depth of 120 m during periods of thermal stratification. Primary production also is low, with the maximum levels occurring between the depth of 40 and 80 m. Phytoplankton taxa are spatially segregated from each other within the water column to a depth of 200 m in summer and early fall. The same generalization applies to the zooplankton taxa. Water level, clarity, concentrations of total chlorophyll, primary production, and abundances of zooplankton and introduced kokanee salmon exhibit long-term fluctuations. Based primarily on a recent 10-year study of the lake, the lake is considered to be pristine, except for the consequences of fish introductions.

Ozone formation in pulsed SDBD in a wide pressure range

NASA Astrophysics Data System (ADS)

Starikovskiy, Andrey; Nudnova, Maryia; mipt Team

2011-10-01

Ozone concentration in surface anode-directed DBD for wide pressure range (150 - 1300 torr) was experimentally measured. Voltage and pressure effect were investigated. Reduced electric field was measured for anode-directed and cathode-directed SDBD. E/n values in cathode-directed SDBD is higher than in cathode-directed on 50 percent at atmospheric pressure. E/n value increase leads to decrease the rate of oxygen dissociation and Ozone formation at lower pressures. Radiating region thickness of sliding discharge was measured. Typical thickness of radiating zone is 0.4-1.0 mm within pressure range 220-740 torr. It was shown that high-voltage pulsed nanosecond discharge due to high E/n value produces less Ozone with compare to other discharges. Kinetic model was proposed to describe Ozone formation in the pulsed nanosecond SDBD.

Metabolic Potential and Activity in Fluids of the Coast Range Ophiolite Microbial Observatory, California, USA

NASA Technical Reports Server (NTRS)

Hoehler, T.; Som, S.; Schrenk, M.; McCollom, T.; Cardace, D.

2016-01-01

Metabolic potential and activity associated with hydrogen and carbon monoxide were characterized in fluids sampled from the the Coast Range Ophiolite Microbial Observatory (CROMO). CROMO consists of two clusters of science-dedicated wells drilled to varying depths up to 35m in the actively serpentinizing, Jurassic-age Coast Range Ophiolite of Northern California, along with a suite of pre-existing monitoring wells at the same site. Consistent with the fluid chemistry observed in other serpentinizing systems, CROMO fluids are highly alkaline, with pH up to 12.5, high in methane, with concentrations up 1600 micromolar, and low in dissolved inorganic carbon (DIC), with concentrations of 10's to 100's of micromolar. CROMO is conspicuous for fluid H2 concentrations that are consistently sub-micromolar, orders of magnitude lower than is typical of other systems. However, higher H2 concentrations (10's -100's of micromolar) at an earlier stage of fluid chemical evolution are predicted by, or consistent with: thermodynamic models for fluid chemistry based on parent rock composition equivalent to local peridotite and with water:rock ratio constrained by observed pH; the presence of magnetite at several wt% in CROMO drill cores; and concentrations of formate and carbon monoxide that would require elevated H2 if formed in equilibrium with H2 and DIC. Calculated Gibbs energy changes for reaction of H2 and CO in each of several metabolisms, across the range of fluid composition encompassed by the CROMO wells, range from bioenergetically feasible (capable of driving ATP synthesis) to thermodynamically unfavorable. Active consumption relative to killed controls was observed for both CO and H2 during incubation of fluids from the pre-existing monitoring wells; in incubations of freshly cored solids, consumption was only observed in one sample set (corresponding to the lowest pH) out of three. The specific metabolisms by which H2 and CO are consumed remain to be determined.

Nitrogen transport from tallgrass prairie watersheds

USGS Publications Warehouse

Dodds, W.K.; Blair, J.M.; Henebry, G.M.; Koelliker, J.K.; Ramundo, R.; Tate, C.M.

1996-01-01

Discharge and N content of surface water flowing from four Karat watersheds on Konza Prairie Research Natural Area, Kansas, managed with different burn frequencies, were monitored from 1986 to 1992. The goal was to establish the influence of natural processes (climate, fire, and bison grazing) on N transport and concentration in streams. Streams were characterized by variable flow, under conditions that included an extreme flood and a drought during which all channels were dry for over a year. The estimated groundwater/stream water discharge ratio varied between 0.15 to 6.41. Annual N transport by streams, averaged across all watersheds and years, was 0.16 kg N ha-1 yr-1. Annual N transport per unit area also increased as the watershed area increased and as precipitation increased. Total annual transport of N horn the prairie via streams ranged from 0.01 to 6.0% of the N input from precipitation. Nitrate and total N concentrations in surface water decreased (P < 0.001, r values ranged from 0.140.26) as length of time since last fire increased. Increased watershed area was correlated negatively (P < 0.0001) to stream water concentrations of NO3-N and total N (r values = -0.43 and -0.20, respectively). Low N concentration is typical of these streams, with NH4/+-N concentrations below 1.0 ??g L-1, NO3-N ranging from below 1.4 to 392 ??g L-1, and total N from 3.0 to 714 ??g L-1. These data provide an important baseline for evaluating N transport and stream water quality from unfertilized grasslands.

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.

A novel amperometric biosensor based on banana peel (Musa cavendish) tissue homogenate for determination of phenolic compounds.

PubMed

Ozcan, Hakki Mevlut; Sagiroglu, Ayten

2010-08-01

In this study the biosensor was constructed by immobilizing tissue homogenate of banana peel onto a glassy carbon electrode surface. Effects of immobilization materials amounts, effects of pH, buffer concentration and temperature on biosensor response were studied. In addition, the detection ranges of 13 phenolic compounds were obtained with the help of the calibration graphs. Storage stability, repeatability of the biosensor, inhibitory effect and sample applications were also investigated. A typical calibration curve for the sensor revealed a linear range of 10-80 microM catechol. In reproducibility studies, variation coefficient and standard deviation were calculated as 2.69%, 1.44 x 10(-3) microM, respectively.

One-carbon (bio ?) Geochemistry in Subsurface Waters of the Serpentinizing Coast Range Ophiolite

NASA Technical Reports Server (NTRS)

Hoehler, Tori M.; Mccollom, Tom; Schrenk, Matt; Cardace, Dawn

2011-01-01

Serpentinization - the aqueous alteration of ultramafic rocks - typically imparts a highly reducing and alkaline character to the reacting fluids. In turn, these can influence the speciation and potential for metabolism of one-carbon compounds in the system. We examined the aqueous geochemistry and assessed the biological potential of one-carbon compounds in the subsurface of the McLaughlin Natural Reserve (Coast Range Ophiolite, California, USA). Fluids from wells sunk at depths of 25-90 meters have pH values ranging from 9.7 to 11.5 and dissolved inorganic carbon (DIC concentrations) generally below 60 micromolar. Methane is present at concentrations up to 1.3 millimolar (approximately one-atmosphere saturation), and hydrogen concentrations are below 15 nanomolar, suggesting active consumption of H2 and production of CH4. However, methane production from CO2 is thermodynamically unfavorable under these conditions. Additionally, the speciation of DIC predominantly into carbonate at these high pH values creates a problem of carbon availability for any organisms that require CO2 (or bicarbonate) for catabolism or anabolism. A potential alternative is carbon monoxide, which is present in these waters at concentrations 2000-fold higher than equilibrium with atmospheric CO. CO is utilized in a variety of metabolisms, including methanogenesis, and bioavailability is not adversely affected by pH-dependent speciation (as for DIC). Methanogenesis from CO under in situ conditions is thermodynamically favorable and would satisfy biological energy requirements with respect to both Gibbs Energy yield and power.

Wintertime characteristic of peroxyacetyl nitrate in the Chengyu district of southwestern China.

PubMed

Zhu, Honglin; Gao, Tianyu; Zhang, Jianbo

2018-06-02

Atmospheric concentrations of peroxyacetyl nitrate (PAN) were measured in Ziyang in December 2012 to provide basic knowledge of PAN in the Chengyu district and offer recommendations for air pollution management. The PAN pollution was relatively severe in Ziyang in winter, with the maximum and average PAN concentrations of 1.61 and 0.55 ppbv, respectively, and a typical single-peak diurnal trend in PAN and theoretical PAN lost by thermal decomposition (TPAN) were observed. PAN and O 3 concentrations were correlated (R 2  = 0.52) and the ratios of daily maximum PAN to O 3 ([PAN]/[O 3 ] ratio) ranged from 0.013 to 0.108, with an average of 0.038. Both acetone and methyl ethyl ketone (MEK) were essential for producing the acetylperoxy radicals (PA) and subsequently PAN in Ziyang in winter, and PAN concentrations at the sampling site exhibited more sensitivity to volatile organic compound (VOC) concentrations than nitrogen oxide (NO x ) levels. Therefore, management should focus on reducing VOCs emissions, in particular those that produce acetone and MEK through photolysis and oxidizing reactions. In addition, the influence of relative humidity (RH) on the heterogeneous reactions between PAN and PM 2.5 in the atmospheric environment may have led to the strong correlation between observed PM 2.5 and PAN in Ziyang in winter. Furthermore, a typical air pollution event was observed on 17-18 December 2012, which Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) and PSCF simulations suggest that it was caused by the local formation and the regional transport of polluted air masses from Hanzhong, Nanchong, and Chengdu.

Sulfur geochemistry of hydrothermal waters in Yellowstone National Park: I. The origin of thiosulfate in hot spring waters

USGS Publications Warehouse

Xu, Y.; Schoonen, M.A.A.; Nordstrom, D. Kirk; Cunningham, K.M.; Ball, J.W.

1998-01-01

Thiosulfate (S2O2-3), polythionate (SxO2-6), dissolved sulfide (H2S), and sulfate (SO2-4) concentrations in thirty-nine alkaline and acidic springs in Yellowstone National Park (YNP) were determined. The analyses were conducted on site, using ion chromatography for thiosulfate, polythionate, and sulfate, and using colorimetry for dissolved sulfide. Thiosulfate was detected at concentrations typically less than 2 ??mol/L in neutral and alkaline chloride springs with low sulfate concentrations (C1-/SO2-4 > 25). The thiosulfate concentration levels are about one to two orders of magnitude lower than the concentration of dissolved sulfide in these springs. In most acid sulfate and acid sulfate-chloride springs (Cl-/SO2-4 < 10), thiosulfate concentrations were also typically lower than 2 ??mol/L. However, in some chloride springs enriched with sulfate (Cl-/SO2-4 between 10 to 25), thiosulfate was found at concentrations ranging from 9 to 95 ??mol/L, higher than the concentrations of dissolved sulfide in these waters. Polythionate was detected only in Cinder Pool, Norris Geyser basin, at concentrations up to 8 ??mol/L, with an average S-chain-length from 4.1 to 4.9 sulfur atoms. The results indicate that no thiosulfate occurs in the deeper parts of the hydrothermal system. Thiosulfate may form, however, from (1) hydrolysis of native sulfur by hydrothermal solutions in the shallower parts (<50 m) of the system, (2) oxidation of dissolved sulfide upon mixing of a deep hydrothermal water with aerated shallow groundwater, and (3) the oxidation of dissolved sulfide by dissolved oxygen upon discharge of the hot spring. Upon discharge of a sulfide-containing hydrothermal water, oxidation proceeds rapidly as atmospheric oxygen enters the water. The transfer of oxygen is particularly effective if the hydrothermal discharge is turbulent and has a large surface area.

Major and trace elements in organically or conventionally produced milk.

PubMed

Hermansen, John E; Badsberg, Jens H; Kristensen, Troels; Gundersen, Vagn

2005-08-01

A total of 480 samples of milk from 10 organically and 10 conventionally producing dairy farms in Denmark and covering 8 sampling periods over 1 year (triplicate samplings) were analysed for 45 trace elements and 6 major elements by high-resolution inductively coupled plasma mass spectrometry and inductively coupled plasma atomic emission spectrometry. Sampling, sample preparation, and analysis of the samples were performed under carefully controlled contamination-free conditions. The dairy cattle breeds were Danish-Holstein or Jersey. Sources of variance were quantified, and differences between production systems and breeds were tested. The major source of variation for most elements was week of sampling. Concentrations of Al, Cu, Fe, Mo, Rb, Se, and Zn were within published ranges. Concentrations of As, Cd, Cr, Mn and Pb were lower, and concentrations of Co and Sr were higher than published ranges. Compared with Holsteins, Jerseys produced milk with higher concentrations of Ba, Ca, Cu, Fe, Mg, Mn, Mo, P, Rh, and Zn and with a lower concentration of Bi. The organically produced milk, compared with conventionally produced milk, contained a significantly higher concentration of Mo (48 v. 37 ng/g) and a lower concentration of Ba (43 v. 62 ng/g), Eu (4 v. 7 ng/g), Mn (16 v. 20 ng/g) and Zn (4400 v. 5150 ng/g respectively). The investigation yielded typical concentrations for the following trace elements in milk, for which no or very few data are available: Ba, Bi, Ce, Cs, Eu, Ga, Gd, In, La, Nb, Nd, Pd, Pr, Rh, Sb, Sm, Tb, Te, Th, Ti, Tl, U, V, Y, and Zr.

Variability in δ13C values between individual Daphnia ephippia: Implications for palaeo-studies

NASA Astrophysics Data System (ADS)

Schilder, Jos; van Roij, Linda; Reichart, Gert-Jan; Sluijs, Appy; Heiri, Oliver

2018-06-01

The stable carbon isotope ratio (δ13C value) of Daphnia spp. resting egg shells (ephippia) provides information on past changes in Daphnia diet. Measurements are typically performed on samples of ≥20 ephippia, which obscures the range of values associated with individual ephippia. Using a recently developed laser ablation-based technique, we perform multiple δ13C analyses on individual ephippia, which show a high degree of reproducibility (standard deviations 0.1-0.5‰). We further measured δ13C values of 13 ephippia from surface sediments of three Swiss lakes. In the well-oxygenated lake with low methane concentrations, δ13C values are close to values typical for algae (-31.4‰) and the range in values is relatively small (5.8‰). This variability is likely driven by seasonal (or inter-annual) variability in algae δ13C values. In two seasonally anoxic lakes with higher methane concentrations, average values were lower (-41.4 and -43.9‰, respectively) and the ranges much larger (10.7 and 20.0‰). We attribute this variability to seasonal variation in incorporation of methane-derived carbon. In one lake we identify two statistically distinct isotopic populations, which may reflect separate production peaks. The potentially large within-sample variability should be considered when interpreting small-amplitude, short-lived isotope excursions based on samples consisting of few ephippia. We show that measurements on single ephippia can be performed using laser ablation, which allows for refined assessments of past Daphnia diet and carbon cycling in lake food webs. Furthermore, our study provides a basis for similar measurements on other chitinous remains (e.g. from chironomids, bryozoans).

Variation in Nectar Volume and Sugar Concentration of Allium ursinum L. ssp. ucrainicum in Three Habitats

PubMed Central

Farkas, Ágnes; Molnár, Réka; Morschhauser, Tamás; Hahn, István

2012-01-01

Floral nectar volume and concentration of ramson (Allium ursinum L. ssp. ucrainicum) were investigated in three different habitats, including two types of sessile oak-hornbeam association on brown forest soil with clay illuviation and a silver lime-flowering ash rock forest association on rendzina. Daily nectar production ranged from 0.1 to 3.8 μL per flower with sugar concentrations of 25 to 50%. Mean nectar volumes and concentrations showed significant differences between freely exposed flowers and covered flowers, which had been isolated from flower visitors 24 h prior to nectar studies. Both the amount and quality of nectar were affected by microclimatic conditions and soil properties and varied between populations at different habitats. In the silver lime-flowering ash rock-forest association mean nectar volumes and concentrations were lower than in a typical sessile oak-hornbeam association on three occasions, the difference being significant in two cases. During full bloom, the date of sampling did not have a profound effect on either nectar volume or concentration. PMID:22619588

Observations of ozone depletion events in a Finnish boreal forest

NASA Astrophysics Data System (ADS)

Chen, Xuemeng; Quéléver, Lauriane L. J.; Fung, Pak L.; Kesti, Jutta; Rissanen, Matti P.; Bäck, Jaana; Keronen, Petri; Junninen, Heikki; Petäjä, Tuukka; Kerminen, Veli-Matti; Kulmala, Markku

2018-01-01

We investigated the concentrations and vertical profiles of ozone over a 20-year period (1996-2016) at the SMEAR II station in southern Finland. Our results showed that the typical daily median ozone concentrations were in the range of 20-50 ppb with clear diurnal and annual patterns. In general, the profile of ozone concentrations illustrated an increase as a function of heights. The main aim of our study was to address the frequency and strength of ozone depletion events at this boreal forest site. We observed more than a thousand of 10 min periods at 4.2 m, with ozone concentrations below 10 ppb, and a few tens of cases with ozone concentrations below 2 ppb. Among these observations, a number of ozone depletion events that lasted for more than 3 h were identified, and they occurred mainly in autumn and winter months. The low ozone concentrations were likely related to the formation of a low mixing layer under the conditions of low temperatures, low wind speeds, high relative humidities and limited intensity of solar radiation.

Pharmaceutical Formulation Facilities as Sources of Opioids and Other Pharmaceuticals to Wastewater Treatment Plant Effluents

PubMed Central

2010-01-01

Facilities involved in the manufacture of pharmaceutical products are an under-investigated source of pharmaceuticals to the environment. Between 2004 and 2009, 35 to 38 effluent samples were collected from each of three wastewater treatment plants (WWTPs) in New York and analyzed for seven pharmaceuticals including opioids and muscle relaxants. Two WWTPs (NY2 and NY3) receive substantial flows (>20% of plant flow) from pharmaceutical formulation facilities (PFF) and one (NY1) receives no PFF flow. Samples of effluents from 23 WWTPs across the United States were analyzed once for these pharmaceuticals as part of a national survey. Maximum pharmaceutical effluent concentrations for the national survey and NY1 effluent samples were generally <1 μg/L. Four pharmaceuticals (methadone, oxycodone, butalbital, and metaxalone) in samples of NY3 effluent had median concentrations ranging from 3.4 to >400 μg/L. Maximum concentrations of oxycodone (1700 μg/L) and metaxalone (3800 μg/L) in samples from NY3 effluent exceeded 1000 μg/L. Three pharmaceuticals (butalbital, carisoprodol, and oxycodone) in samples of NY2 effluent had median concentrations ranging from 2 to 11 μg/L. These findings suggest that current manufacturing practices at these PFFs can result in pharmaceuticals concentrations from 10 to 1000 times higher than those typically found in WWTP effluents. PMID:20521847

Quantitative determination of caffeine and alcohol in energy drinks and the potential to produce positive transdermal alcohol concentrations in human subjects.

PubMed

Ayala, Jessica; Simons, Kelsie; Kerrigan, Sarah

2009-01-01

The purpose of this study was to determine whether non-alcoholic energy drinks could result in positive "alcohol alerts" based on transdermal alcohol concentration (TAC) using a commercially available electrochemical monitoring device. Eleven energy drinks were quantitatively assayed for both ethanol and caffeine. Ethanol concentrations for all of the non-alcoholic energy drinks ranged in concentration from 0.03 to 0.230% (w/v) and caffeine content per 8-oz serving ranged from 65 to 126 mg. A total of 15 human subjects participated in the study. Subjects consumed between 6 and 8 energy drinks over an 8-h period. The SCRAM II monitoring device was used to determine TACs every 30 min before, during, and after the study. None of the subjects produced TAC readings that resulted in positive "alcohol alerts". TAC measurements for all subjects before, during and after the energy drink study period (16 h total) were <0.02% (w/v). Subjects in the study consumed a quantity of non-alcoholic energy drink that greatly exceeds what would be considered typical. Based on these results, it appears that energy drink consumption is an unlikely explanation for elevated TACs that might be identified as potential drinking episodes or "alcohol alerts" using this device.

Photochemistry of PAHs in cosmic water ice. The effect of concentration on UV-VIS spectroscopy and ionization efficiency

NASA Astrophysics Data System (ADS)

Cuylle, Steven H.; Allamandola, Louis J.; Linnartz, Harold

2014-02-01

Context. Observations and models show that polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the interstellar medium. Like other molecules in dense clouds, PAHs accrete onto interstellar dust grains, where they are embedded in an ice matrix dominated by water. In the laboratory, mixed molecular ices (not containing PAHs) have been extensively studied using Fourier transform infrared absorption spectroscopy. Experiments including PAHs in ices have started, however, the concentrations used are typically much higher than the concentrations expected for interstellar ices. Optical spectroscopy offers a sensitive alternative. Aims: We report an experimental study of the effect PAH concentration has on the electronic spectra and the vacuum UV (VUV) driven processes of PAHs in water-rich ices. The goal is to apply the outcome to cosmic ices. Methods: Optical spectroscopic studies allow us to obtain in-situ and quasi real-time electronic solid state spectra of two prototypical PAHs (pyrene and coronene) embedded in water ice under VUV photoprocessing. The study is carried out on PAH:H2O concentrations in the range of 1:30 000 to pure PAH, covering the temperature range from 12 to 125 K. Results: PAH concentration strongly influences the efficiency of PAH cation formation. At low concentrations, ionization efficiencies are over 60% dropping to about 15% at 1:1000. Increasing the PAH concentration reveals spectral broadening in neutral and cation PAH spectra attributed to PAH clustering inside the ice. At the PAH concentrations expected for interstellar ices, some 10 to 20% may be present as cations. The presence of PAHs in neutral and ion form will add distinctive absorption bands to cosmic ice optical spectra and this may serve as a tool to determine PAH concentrations.

Concentration and Risk Evaluation of Polycyclic Aromatic Hydrocarbons in Urban Soil in the Typical Semi-Arid City of Xi'an in Northwest China.

PubMed

Wang, Lijun; Zhang, Shengwei; Wang, Li; Zhang, Wenjuan; Shi, Xingmin; Lu, Xinwei; Li, Xiaoping; Li, Xiaoyun

2018-03-27

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants, presenting potential threats to the ecological environment and human health. Sixty-two urban soil samples were collected in the typical semi-arid city of Xi'an in Northwest China. They were analyzed for concentration, pollution, and ecological and health risk of sixteen U.S. Environmental Protection Agency priority PAHs. The total concentrations of the sixteen PAHs (Σ16PAHs) in the urban soil ranged from 390.6 to 10,652.8 µg/kg with an average of 2052.6 µg/kg. The concentrations of some individual PAHs in the urban soil exceeded Dutch Target Values of Soil Quality and the Σ16PAHs represented heavy pollution. Pyrene and dibenz[a,h]anthracene had high ecological risk to aquatic/soil organisms, while other individual PAHs showed low ecological risk. The total ecological risk of PAHs to aquatic/soil organisms is classified as moderate. Toxic equivalency quantities (TEQs) of the sixteen PAHs varied between 21.16 and 1625.78 µg/kg, with an average of 423.86 µg/kg, indicating a relatively high toxicity potential. Ingestion and dermal adsorption of soil dust were major pathways of human exposure to PAHs from urban soil. Incremental lifetime cancer risks (ILCRs) of human exposure to PAHs were 2.86 × 10 -5 for children and 2.53 × 10 -5 for adults, suggesting that the cancer risk of human exposure to PAHs from urban soil is acceptable.

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.

Sweetness and other sensory properties of model fruit drinks: Does viscosity have an impact?

PubMed

Brandenstein, Cai V S; Busch-Stockfisch, Mechthild; Fischer, Markus

2015-03-15

The impact of thickening agents and viscosity levels on sensory perception was studied in model fruit drinks. Four formulations were prepared that varied in the sweetener blend (erythritol, maltitol and/or steviol glycosides). Locust bean gum and its blends with either xanthan or carrageenan were used to adjust viscosity levels (20, 40, and 70 mPa s). The ranges of viscosity and sweetness level were selected to represent a typical concentration range in commercially available beverages. An increase in viscosity resulted in significant increases in pulpiness, sliminess and perceived viscosity (P-values ≤ 0.001), which were not dependent on sweeteners or hydrocolloid type. Taste perception remained largely unchanged irrespective of the hydrocolloid used. The impact of viscosity on sweetness and taste perception was much smaller in the concentrations used than has been generally reported. The effect of the type of hydrocolloid on the perception of taste attributes was greater than that of viscosity. © 2014 Society of Chemical Industry.

Chlorophyll maxima in mountain ponds and lakes, Mount Rainier National Park, Washington State, USA

USGS Publications Warehouse

Larson, Gary L.

2000-01-01

Hypolimnetic chlorophyll maxima are common in clear lakes and often occur at depths with between 1 and 0.1% of the surface incident light. Little is known, however, about the concentrations of chlorophyll in thermally unstratified mountain ponds and how these concentrations compare to epilimnetic and hypolimnetic concentrations in mountain lakes. The objectives of this study were to document the concentrations of chlorophyll in thermally unstratified ponds and stratified lakes in Mount Rainier National Park (MORA) and to compare the results with concentrations and distributions of chlorophyll in clear-deep lakes in the Oregon Cascade Range and the Sierra Nevada Range. Thirty-two ponds (<2.5 m deep) and 14 lakes(>9.9 m deep) were sampled primarily during the summers of 1992 to 1996 at MORA. Water samples from near the surface (0.1–0.5 m) of ponds and near the surface and near the bottom of lakes were collected over the deepest part of each system. One exception, Mowich Lake, was sampled at seven depths between the surface and 50 m (Z=58.6 m). Chlorophyll concentrations were low in all systems, but higher in ponds (average 1.8 μg·L−1) than in lakes. Chlorophyll concentrations were higher in hypolimnetic lake samples (average 0.7 μg·L−1) than in epilimnetic lake samples (average 0.2 μg·L−1). Elevated concentrations of chlorophyll in mountain ponds, relative to those in hypolimnetic lake samples, may have been influenced by increased nutrient availability from interactions at the mud-water interface and, in this park, defecation by elk that used many of the ponds as wallows. Mowich Lake showed a chlorophyll maximum (~1.5 μg·L−1) near the lake bottom. Based on Secchi disk clarity readings, the depth of 1.0% incident surface solar radiation was greater than the maximum depths of the ponds and lakes. Comparative data from other clear-deep lakes in the Oregon Cascade Range and Sierra Nevada Range suggested that deep-chlorophyll maxima (~1.5 μg·L−1) occurred at <1.0% and > 0.1% of the incident surface solar radiation, and that the typical maximum depths ranged between 75 and 140 m during thermal stratification.

Cumulus cloud venting of mixed layer ozone

NASA Technical Reports Server (NTRS)

Ching, J. K. S.; Shipley, S. T.; Browell, E. V.; Brewer, D. A.

1985-01-01

Observations are presented which substantiate the hypothesis that significant vertical exchange of ozone and aerosols occurs between the mixed layer and the free troposphere during cumulus cloud convective activity. The experiments utilized the airborne Ultra-Violet Differential Absorption Lidar (UV-DIAL) system. This system provides simultaneous range resolved ozone concentration and aerosol backscatter profiles with high spatial resolution. Evening transects were obtained in the downwind area where the air mass had been advected. Space-height analyses for the evening flight show the cloud debris as patterns of ozone typically in excess of the ambient free tropospheric background. This ozone excess was approximately the value of the concentration difference between the mixed layer and free troposphere determined from independent vertical soundings made by another aircraft in the afternoon.

Water-soluble organic nitrogen in atmospheric fine particles (PM2.5) from northern California

NASA Astrophysics Data System (ADS)

Zhang, Qi; Anastasio, Cort; Jimenez-Cruz, Mike

2002-06-01

Recent studies have suggested that organic nitrogen (ON) is a ubiquitous and significant component of atmospheric dry and wet deposition, but very little is known about the concentrations and speciation of organic nitrogen in aerosol particles. In addition, while amino compounds also appear to be ubiquitous in atmospheric condensed phases, their contribution to organic nitrogen has not been previously quantified. To address these issues, we have characterized the water-soluble organic nitrogen and amino compounds in fine particles (PM2.5) collected in Davis, California, over a period of 1 year. Concentrations of water-soluble organic nitrogen (WSON) ranged from 3.1-57.8 nmol N m-3 air, peaking during winter and early spring, and typically accounted for ~20% of total nitrogen in Davis PM2.5. Assuming an average N-normalized molecular weight of 100 Da per N atom for WSON, particulate organic nitrogen had a median mass concentration of 1.6 μg m-3 air, and typically represented 18% of the total fine particle mass. The average mass of water-soluble ON in Davis PM2.5 was comparable to that of sulfate during the summer, but was significantly higher in winter. Total amino compounds (free plus combined forms) made up a significant portion of particulate organic nitrogen (median value equal to 23%), primarily due to the presence of combined amino compounds such as proteins and peptides. Total amino compounds had a median mass concentration of 290 ng m-3 air, and typically accounted for 3.3% of the total fine particle mass. These results indicate that organic nitrogen is a significant component of fine particles in northern California, and suggest that this group of compounds might play an important role in the ecological, radiative, and potential health effects of atmospheric fine particles in this region.

High doses of bone morphogenetic protein 2 induce structurally abnormal bone and inflammation in vivo.

PubMed

Zara, Janette N; Siu, Ronald K; Zhang, Xinli; Shen, Jia; Ngo, Richard; Lee, Min; Li, Weiming; Chiang, Michael; Chung, Jonguk; Kwak, Jinny; Wu, Benjamin M; Ting, Kang; Soo, Chia

2011-05-01

The major Food and Drug Association-approved osteoinductive factors in wide clinical use are bone morphogenetic proteins (BMPs). Although BMPs can promote robust bone formation, they also induce adverse clinical effects, including cyst-like bone formation and significant soft tissue swelling. In this study, we evaluated multiple BMP2 doses in a rat femoral segmental defect model and in a minimally traumatic rat femoral onlay model to determine its dose-dependent effects. Results of our femoral segmental defect model established a low BMP2 concentration range (5 and 10 μg/mL, total dose 0.375 and 0.75 μg in 75 μg total volume) unable to induce defect fusion, a mid-range BMP2 concentration range able to fuse the defect without adverse effects (30 μg/mL, total dose 2.25 μg in 75 μg total volume), and a high BMP2 concentration range (150, 300, and 600 μg/mL, total dose 11.25, 22.5, and 45 μg in 75 μg total volume) able to fuse the defect, but with formation of cyst-like bony shells filled with histologically confirmed adipose tissue. In addition, compared to control, 4 mg/mL BMP2 also induced significant tissue inflammatory infiltrates and exudates in the femoral onlay model that was accompanied by increased numbers of osteoclast-like cells at 3, 7, and 14 days. Overall, we consistently reproduced BMP2 side effects of cyst-like bone and soft tissue swelling using high BMP2 concentration approaching the typical human 1500 μg/mL.

High Doses of Bone Morphogenetic Protein 2 Induce Structurally Abnormal Bone and Inflammation In Vivo

PubMed Central

Zara, Janette N.; Siu, Ronald K.; Zhang, Xinli; Shen, Jia; Ngo, Richard; Lee, Min; Li, Weiming; Chiang, Michael; Chung, Jonguk; Kwak, Jinny; Wu, Benjamin M.; Ting, Kang

2011-01-01

The major Food and Drug Association–approved osteoinductive factors in wide clinical use are bone morphogenetic proteins (BMPs). Although BMPs can promote robust bone formation, they also induce adverse clinical effects, including cyst-like bone formation and significant soft tissue swelling. In this study, we evaluated multiple BMP2 doses in a rat femoral segmental defect model and in a minimally traumatic rat femoral onlay model to determine its dose-dependent effects. Results of our femoral segmental defect model established a low BMP2 concentration range (5 and 10 μg/mL, total dose 0.375 and 0.75 μg in 75 μg total volume) unable to induce defect fusion, a mid-range BMP2 concentration range able to fuse the defect without adverse effects (30 μg/mL, total dose 2.25 μg in 75 μg total volume), and a high BMP2 concentration range (150, 300, and 600 μg/mL, total dose 11.25, 22.5, and 45 μg in 75 μg total volume) able to fuse the defect, but with formation of cyst-like bony shells filled with histologically confirmed adipose tissue. In addition, compared to control, 4 mg/mL BMP2 also induced significant tissue inflammatory infiltrates and exudates in the femoral onlay model that was accompanied by increased numbers of osteoclast-like cells at 3, 7, and 14 days. Overall, we consistently reproduced BMP2 side effects of cyst-like bone and soft tissue swelling using high BMP2 concentration approaching the typical human 1500 μg/mL. PMID:21247344

Genotoxic effects of daily personal exposure to particle mass and number concentrations on buccal cells

NASA Astrophysics Data System (ADS)

de Almeida, Daniela S.; da Costa, Silvano César; Ribeiro, Marcos; Moreira, Camila A. B.; Beal, Alexandra; Squizzato, Rafaela; Rudke, Anderson Paulo; Rafee, Sameh Adib Abou; Martins, Jorge A.; Palioto, Graciana Freitas; Kumar, Prashant; Martins, Leila D.

2018-03-01

The aim of this study is to assess personal exposure to Particle Number Concentrations (PNC) in four size ranges between 0.3 and 10 μm, and particulate matter (PM1; PM2.5; PM4; PM10) in order to evaluate possible genotoxic effects through a comet assay in buccal cells. A convenience cohort of 30 individuals from a Brazilian medium-sized city was selected. These individuals aged between 20 and 61 and worked in typical job categories (i.e., administrative, commerce, education, general services and transport). They were recruited to perform personal exposure measurements during their typical daily routine activities, totaling 240 h of sampling. The 8-h average mass concentrations in air for volunteers ranged from 2.4 to 31.8 μg m-3 for PM1, 4.2-45.1 μg m-3 for PM2.5, 7.9-66.1 μg m-3 for PM4 and from 23.1 to 131.7 μg m-3 for PM10. The highest PNC variation was found for 0.3-0.5 range, between 14 and 181 particles cm-3, 1 to 14 particles cm-3 for the 0.5-1.0 range, 0.2 to 2 particles cm-3 for the 1.0-2.5 range, and 0.06 to 0.7 particles cm-3 for the 2.5-10 range. Volunteers in the 'education' category experienced the lowest inhaled dose of PM2.5, as opposed to those involved in 'commercial' activities with the highest doses for PM10 (1.63 μg kg-1 h-1) and PM2.5 (0.61 μg kg-1 h-1). The predominant cause for these high doses was associated with the proximity of the workplace to the street and vehicle traffic. The comet assay performed in buccal cells indicated that the volunteers in 'commerce' category experienced the highest damage to their DeoxyriboNucleic Acid (DNA) compared with the control category (i.e. 'education'). These results indicate the variability in personal exposure of the volunteers in different groups, and the potential damage to DNA was much higher for those spending time in close proximity to the vehicle sources (e.g. commercial services) leading to exposure to a higher fraction of fine particles. This study builds understanding on the exposure of people in different job categories, and provide policy makers with useful information to tackle this neglected issue.

Geochemical controls of elevated arsenic concentrations in groundwater, Ester Dome, Fairbanks district, Alaska

USGS Publications Warehouse

Verplanck, P.L.; Mueller, S.H.; Goldfarb, R.J.; Nordstrom, D. Kirk; Youcha, E.K.

2008-01-01

Ester Dome, an upland area near Fairbanks, Alaska, was chosen for a detailed hydrogeochemical study because of the previously reported elevated arsenic in groundwater, and the presence of a large set of wells amenable to detailed sampling. Ester Dome lies within the Fairbanks mining district, where gold-bearing quartz veins, typically containing 2-3??vol.% sulfide minerals (arsenopyrite, stibnite, and pyrite), have been mined both underground and in open cuts. Gold-bearing veins on Ester Dome occur in shear zones and the sulfide minerals in these veins have been crushed to fine-grained material by syn- or post-mineralization movement. Groundwater at Ester Dome is circumneutral, Ca-HCO3 to Ca-SO4 type, and ranges from dilute (specific conductance of 48????S/cm) to more concentrated (specific conductance as high as 2070????S/cm). In general, solute concentrations increase down hydrologic gradient. Redox species indicate that the groundwaters range from oxic to sub-oxic (low dissolved oxygen, Fe(III) reduction, no SO4 reduction). Waters with the highest Fe concentrations, as high as 10.7??mg/L, are the most anoxic. Dissolved As concentrations range from < 1 to 1160????g/L, with a median value of 146????g/L. Arsenic concentrations are not correlated with specific conductance or Fe concentrations, suggesting that neither groundwater residence time, nor reductive dissolution of iron oxyhydroxides, control the arsenic chemistry. Furthermore, As concentrations do not covary with other constituents that form anions and oxyanions in solution (e.g., HCO3, Mo, F, or U) such that desorption of arsenic from clays or oxides also does not control arsenic mobility. Oxidation of arsenopyrite and dissolution of scorodite, in the near-surface environment appears to be the primary control of dissolved As in this upland area. More specifically, the elevated As concentrations are spatially associated with sulfidized shear zones and localities of gold-bearing quartz veins. Consistent with this interpretation, elevated dissolved Sb concentrations (as high as 59????g/L), also correlated with occurrences of hypogene sulfide minerals, were measured in samples with high dissolved As concentrations.

Evaluation of power block arrangements for 100MW scale concentrated solar thermal power generation using top-down design

NASA Astrophysics Data System (ADS)

Post, Alexander; Beath, Andrew; Sauret, Emilie; Persky, Rodney

2017-06-01

Concentrated solar thermal power generation poses a unique situation for power block selection, in which a capital intensive heat source is subject to daily and seasonal fluctuations in intensity. In this study, a method is developed to easily evaluate the favourability of different power blocks for converting the heat supplied by a concentrated solar thermal plant into power at the 100MWe scale based on several key parameters. The method is then applied to a range of commercially available power cycles that operate over different temperatures and efficiencies, and with differing capital costs, each with performance and economic parameters selected to be typical of their technology type, as reported in literature. Using this method, the power cycle is identified among those examined that is most likely to result in a minimum levelised cost of energy of a solar thermal plant.

Assessment of the performance of a compact concentric spectrometer system for Atmospheric Differential Optical Absorption Spectroscopy

NASA Astrophysics Data System (ADS)

Whyte, C.; Leigh, R. J.; Lobb, D.; Williams, T.; Remedios, J. J.; Cutter, M.; Monks, P. S.

2009-12-01

A breadboard demonstrator of a novel UV/VIS grating spectrometer has been developed based upon a concentric arrangement of a spherical meniscus lens, concave spherical mirror and curved diffraction grating suitable for a range of atmospheric remote sensing applications from the ground or space. The spectrometer is compact and provides high optical efficiency and performance benefits over traditional instruments. The concentric design is capable of handling high relative apertures, owing to spherical aberration and comma being near zero at all surfaces. The design also provides correction for transverse chromatic aberration and distortion, in addition to correcting for the distortion called "smile", the curvature of the slit image formed at each wavelength. These properties render this design capable of superior spectral and spatial performance with size and weight budgets significantly lower than standard configurations. This form of spectrometer design offers the potential for exceptionally compact instrument for differential optical absorption spectroscopy (DOAS) applications from LEO, GEO, HAP or ground-based platforms. The breadboard demonstrator has been shown to offer high throughput and a stable Gaussian line shape with a spectral range from 300 to 450 nm at 0.5 nm resolution, suitable for a number of typical DOAS applications.

Total selenium and selenium species in irrigation drain inflows to the Salton Sea, California, October 2007 and January 2008

USGS Publications Warehouse

May, Thomas W.; Walther, Michael J.; Saiki, Michael K.; Brumbaugh, William G.

2008-01-01

This report presents the results for two sampling periods (October 2007 and January 2008) during a 4-year monitoring program to characterize selenium concentrations in selected irrigation drains flowing into the Salton Sea, California. Total selenium, selenium species (selenite, selenate, organoselenium), and total suspended solids were determined in water samples, and total selenium was determined in sediment, detritus, and biota that included algae, plankton, midge larvae (family, Chironomidae), and two fish species?western mosquitofish (Gambusia affinis) and sailfin molly (Poecilia latipinna). In addition, sediments were analyzed for percent total organic carbon and particle size. Mean total selenium concentrations in water for both sampling periods ranged from 0.97 to 64.5 micrograms per liter, predominately as selenate, which is typical of waters where selenium is leached out of selenium-containing marine shales and associated soils under alkaline and oxidizing conditions. Total selenium concentrations (micrograms per gram dry weight) ranged as follows: algae, 0.95 to 5.99; plankton, 0.15 to 19.3; midges, 1.39 to 15.4; fish, 3.71 to 25.1; detritus, 0.85 to 21.7; sediment, 0.32 to 7.28.

Total selenium and selenium species in irrigation drain inflows to the Salton Sea, California, April and July 2008

USGS Publications Warehouse

May, Thomas W.; Walther, Michael J.; Saiki, Michael K.; Brumbaugh, William G.

2009-01-01

This report presents the results for two sampling periods (April 2008 and July 2008) during a 4-year monitoring program to characterize selenium concentrations in selected irrigation drains flowing into the Salton Sea, California. Total selenium, selenium species (dissolved selenite, selenate, organoselenium), and total suspended solids were determined in water samples and total selenium was determined in water column particulates and in sediment, detritus, and biota that included algae, plankton, midge larvae (family, Chironomidae), and two fish species - western mosquitofish (Gambusia affinis) and sailfin molly (Poecilia latipinna). In addition, sediments were analyzed for percent total organic carbon and particle size. Mean total selenium concentrations in water for both sampling periods ranged from 1.93 to 44.2 micrograms per liter, predominately as selenate, which is typical of waters where selenium is leached out of selenium-containing marine shales and associated soils under alkaline and oxidizing conditions. Total selenium concentrations (micrograms per gram dry weight) ranged as follows: algae, 0.75 to 3.39; plankton, 0.88 to 4.03; midges, 2.52 to 44.3; fish, 3.37 to 18.9; detritus, 1.11 to 13.6; sediment, 0.11 to 8.93.

Total selenium and selenium species in irrigation drain inflows to the Salton Sea, California, October 2008 and January 2009

USGS Publications Warehouse

May, Thomas W.; Walther, Michael J.; Saiki, Michael K.; Brumbaugh, William G.

2009-01-01

This report presents the results for two sampling periods (October 2008 and January 2009) during a 4-year monitoring program to characterize selenium concentrations in selected irrigation drains flowing into the Salton Sea, California. Total selenium, selenium species (dissolved selenite, selenate, organoselenium), and total suspended solids were determined in water samples. Total selenium also was determined in water column particulates and in sediment, detritus, and biota that included algae, plankton, midge larvae (family, Chironomidae), and two fish species (western mosquitofish, Gambusia affinis, and sailfin molly, Poecilia latipinna). In addition, sediments were analyzed for percent total organic carbon and particle size. Mean total selenium concentrations in water for both sampling periods ranged from 1.00 to 33.6 micrograms per liter, predominately as selenate, which is typical of waters where selenium is leached out of selenium-containing marine shales and associated soils under alkaline and oxidizing conditions. Total selenium concentrations (micrograms per gram dry weight) ranged as follows: algae, 1.52 to 8.26; plankton, 0.79 to 3.66; midges, 2.68 to 50.6; fish, 3.09 to 30.4; detritus, 1.78 to 58.0; and sediment, 0.42 to 10.0.

Bioavailability of heavy metals in water and sediments from a typical Mediterranean Bay (Málaga Bay, Region of Andalucía, Southern Spain).

PubMed

Alonso Castillo, M L; Sánchez Trujillo, I; Vereda Alonso, E; García de Torres, A; Cano Pavón, J M

2013-11-15

Concentrations of heavy metals were measured in sediment and water from Málaga Bay (South Spain). In the later twentieth century, cities such as Málaga, have suffered the impact of mass summer tourism. The ancient industrial activities, and the actual urbanization and coastal development, recreation and tourism, wastewaters treatment facilities, have been sources of marine pollution. In sediments, Ni was the most disturbing metal because Ni concentrations exceeded the effects range low (ERL), concentration at which toxicity could start to be observed in 85% of the samples analyzed. The metal bioavailability decreased in the order: Cd>Ni>Pb>Cu>Cr. In the sea water samples, Cd and Pb were the most disturbing metals because they exceeded the continuous criteria concentration (CCC) of US EPA in a 22.5% and 10.0% of the samples, respectively. Statistical analyses (ANOVA, PCA, CA) were performed. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effects of agricultural practices and vadose zone stratigraphy on nitrate concentration in ground water in Kansas, USA

USGS Publications Warehouse

Townsend, M.A.; Sleezer, R.O.; Macko, S.A.; ,

1996-01-01

Differences in nitrate-N concentrations in,around water in Kansas can be explained by variations in agricultural practices and vadose-zone stratigraphy. In northwestern Kansas, past use of a local stream for tailwater runoff from irrigation and high fertilizer applications for sugar-beet farming resulted in high nitrate-N concentrations (12-60 mg L-1; in both soil and ground water. Nitrogen isotope values from the soil and ground water range from +4 to +8? which is typical for a fertilizer source. In parts of south-central Kansas, the use of crop rotation and the presence of both continuous fine-textured layers and a reducing ground-water chemistry resulted in ground-water nitrate-N values of 10 mg L-1; in both soil and grounwater. Nitrogen isotope values of +3 to +7? indicate a fertilizer source. Crop rotation decreased nitrate-N values in the shallow ground water (9 m). However, deeper ground water showed increasing nitrate-N concentrations as a result of past farming practices.

Spatial variability of total dissolved copper and copper speciation in the inshore waters of Bermuda.

PubMed

Oldham, V E; Swenson, M M; Buck, K N

2014-02-15

Total dissolved copper (Cu) and Cu speciation were examined from inshore waters of Bermuda, in October 2009 and July-August 2010, to determine the relationship between total dissolved Cu, Cu-binding ligands and bioavailable, free, hydrated Cu(2+) concentrations. Speciation was performed using competitive ligand exchange-adsorptive cathodic stripping voltammetry (CLE-ACSV). Mean total dissolved Cu concentrations ranged from 1.4 nM to 19.2 nM, with lowest concentrations at sites further from shore, consistent with previous measurements in the Sargasso Sea, and localized Cu enrichment inshore in enclosed harbors. Ligand concentrations exceeded dissolved [Cu] at most sites, and [Cu(2+)] were correspondingly low at those sites, typically <10(-13) M. One site, Hamilton Harbour, was found to have [Cu] in excess of ligands, resulting in [Cu(2+)] of 10(-10.7) M, and indicating that Cu may be toxic to phytoplankton here. Copyright © 2013 Elsevier Ltd. All rights reserved.

Concentrations of trace elements and iron in the Arctic soils of Belyi Island (the Kara Sea, Russia): patterns of variation across landscapes.

PubMed

Moskovchenko, D V; Kurchatova, A N; Fefilov, N N; Yurtaev, A A

2017-05-01

The concentrations of several trace elements and iron were determined in 26 soil samples from Belyi Island in the Kara Sea (West Siberian sector of Russian Arctic). The major types of soils predominating in the soil cover were sampled. The concentrations of trace elements (mg kg -1 ) varied within the following ranges: 119-561 for Mn, 9.5-126 for Zn, 0.082-2.5 for Cd, <0.5-19.2 for Cu, <0.5-132 for Pb, 0.011-0.081 for Hg, <0.5-10.3 for Co, and 7.6-108 for Cr; the concentration of Fe varied from 3943 to 37,899 mg kg -1 . The impact of particular soil properties (pH, carbon and nitrogen contents, particle-size distribution) on metal concentrations was analyzed by the methods of correlation, cluster, and factor analyses. The correlation analysis showed that metal concentrations are negatively correlated with the sand content and positively correlated with the contents of silt and clay fractions. The cluster analysis allowed separation of the soils into three clusters. Cluster I included the soils with the high organic matter content formed under conditions of poor drainage; cluster II, the low-humus sandy soils of the divides and slopes; and cluster III, saline soils of coastal marshes. It was concluded that the geomorphic position largely controls the soil properties. The obtained data were compared with data on metal concentrations in other regions of the Russian Arctic. In general, the concentrations of trace elements in the studied soils were within the ranges typical of the background Arctic territories. However, some soils of Belyi Island contained elevated concentrations of Pb and Cd.

Flood Simulation based on ArcGIS in the Ungauged Area from Fugu to Wubao of the middle Yellow River

NASA Astrophysics Data System (ADS)

Jin, Shuangyan; Yan, Yiqi; Jiang, Xinhui

2017-12-01

The Qingliangsigou and Jialuhe in the middle Yellow River are selected as the typical tributaries, history flood data in 1980-2013 and Horton infiltration capacity curve are used to calculate the stable infiltration rate and establish the model of runoff yield and concentration, the parameters are calibrated and applied in the ungauged area from Fugu to Wubao. The study area is divided into 20 units based on ArcGIS, Muskingum method parameters in each unit are calibrated, and typical floods of ungauged area from Fugu to Wubao are simulated. The results show that the simulation effects are good: the average error of peak time is about -0.4h, the error of peak discharge is in the forecasting allowable range, and the deterministic coefficient is 0.66.

Occurrence, distribution and sources of organochlorine pesticides (OCPs) in surface sediments from the Lijiang River, a typical karst river of southwestern China.

PubMed

Zhang, Dan; Wang, Yinghui; Yu, Kefu; Li, Pingyang; Zhang, Ruijie; Xu, Yiyin

2014-11-01

The Lijiang River is a typical karst river of southwestern China. Karst-aquifer systems are more vulnerable to contamination compared to other types of aquifers. The occurrence and distribution of organochlorine pesticides (OCPs) in surface sediments from the Lijiang River were investigated to evaluate their potential ecological risks. The total concentrations of them in sediments ranged from 0.80 to 18.73 ng/g dry weight (dw) (mean 6.83 ng/g dw). The residue levels of OCPs varied in the order of HCB > HCHs > DDTs. Compositional analyses of OCPs showed that HCHs and DDTs were mainly from historical usage. The ecological risk assessment suggested that HCHs and DDTs in Lijiang River sediments may cause adverse ecological risks, particularly at sites near agricultural areas.

The field campaigns of the European Tracer Experiment (ETEX). overview and results

NASA Astrophysics Data System (ADS)

Nodop, K.; Connolly, R.; Girardi, F.

As part of the European Tracer Experiment (ETEX) two successful atmospheric experiments were carried out in October and November, 1994. Perfluorocarbon (PFC) tracers were released into the atmosphere in Monterfil, Brittany, and air samples were taken at 168 stations in 17 European countries for 72 h after the release. Upper air tracer measurements were made from three aircraft. During the first experiment a westerly air flow transported the tracer plume north-eastwards across Europe. During the second release the flow was eastwards. The results from the ground sampling network allowed the determination of the cloud evolution as far as Sweden, Poland and Bulgaria. This demonstrated that the PFT technique can be successfully applied in long-range tracer experiments up to 2000 km. Typical background concentrations of the tracer used are around 5-7 fl ℓ -1 in ambient air. Concentrations in the plume ranged from 10 to above 200 fl/ℓ -1. The tracer release characteristics, the tracer concentrations at the ground and in upper air, the routine and additional meteorological observations at the ground level and in upper air, trajectories derived from constant-level balloons and the meteorological input fields for long-range transport models are assembled in the ETEX database. The ETEX database is accessible via the Internet. Here, an overview is given of the design of the experiment, the methods used and the data obtained.

Application of Titration-Based Screening for the Rapid Pilot Testing of High-Throughput Assays.

PubMed

Zhang, Ji-Hu; Kang, Zhao B; Ardayfio, Ophelia; Ho, Pei-i; Smith, Thomas; Wallace, Iain; Bowes, Scott; Hill, W Adam; Auld, Douglas S

2014-06-01

Pilot testing of an assay intended for high-throughput screening (HTS) with small compound sets is a necessary but often time-consuming step in the validation of an assay protocol. When the initial testing concentration is less than optimal, this can involve iterative testing at different concentrations to further evaluate the pilot outcome, which can be even more time-consuming. Quantitative HTS (qHTS) enables flexible and rapid collection of assay performance statistics, hits at different concentrations, and concentration-response curves in a single experiment. Here we describe the qHTS process for pilot testing in which eight-point concentration-response curves are produced using an interplate asymmetric dilution protocol in which the first four concentrations are used to represent the range of typical HTS screening concentrations and the last four concentrations are added for robust curve fitting to determine potency/efficacy values. We also describe how these data can be analyzed to predict the frequency of false-positives, false-negatives, hit rates, and confirmation rates for the HTS process as a function of screening concentration. By taking into account the compound pharmacology, this pilot-testing paradigm enables rapid assessment of the assay performance and choosing the optimal concentration for the large-scale HTS in one experiment. © 2013 Society for Laboratory Automation and Screening.

Fogwater chemistry in a wood-burning community, western Oregon.

PubMed

Muir, P S

1991-01-01

Fogwater chemistry in Corvallis, Oregon, a wood-burning community (pop. approximately 43,000) was compared with the chemistry of fogwater collected in more remote and in more highly industrialized areas. The fogwater was not acidic (median pH = 5.7) and was usually dominated by SO4=, NO3-, and NH4+ whose concentrations were generally lower than in fogwater in other urban areas but higher than in remote areas. Concentrations of formic and acetic acids (medians = 61 and 52 microN, respectively) were comparable to those in fogwater in Los Angeles, California and were typically much higher than concentrations in fogwater from more remote areas. Formate and acetate concentrations were often comparable to those of SO4= and NO3-. Formaldehyde concentrations (range = 0.4-3.0 mg L-1) were comparable to those in fogwater in some urban areas of southern California, yet lower than concentrations in highly industrialized areas of southern California. Because concentrations of organic compounds in Corvallis fogwater were often comparable to those in larger urban areas, sources in addition to motor vehicles must be important in Corvallis. Additional sources may be natural and anthropogenic, the latter including residential wood burning and wood products industries.

[Atmospheric particle formation events in Nanjing during summer 2010].

PubMed

Wang, Hong-Lei; Zhu, Bin; Shen, Li-Juan; Kang, Han-Qing; Diao, Yi-Wei

2012-03-01

Feature of aerosol particle number concentration, condition and impact factor of new particle formation (NPF) were investigated in Nanjing during summer. In this study, aerosol particle number concentration and gaseous pollutants (O3, SO2 and NO2) measurements were carried out by Wide-Range Particle Spectrometer (WPS) and Differential Optical Absorption Spectroscopy (DOAS) in July 2010. Combining with observations from Automatic Weather Station and Backward Trajectory Simulation, the condition and impact factor of NPF were discussed. Results showed that the averaged 10-500 nm particle number concentration was 1.7 x 10(4) cm(-3), similar to some typical observation values in North American and Europe; the 10-25 nm particle number concentration accounted for 25% of the total number concentration. Six NPF events occurred during observation. We analyzed that stable wind speed and direction, strong solar radiation promoted the NPF. The humidity during NPF event varied from 50% to 70%. Results indicated that clean ocean air mass brought from easterly and southerly wind promoted the NPF by Backward Trajectory Model Simulation. During the NPF event, the 10 - 25 nm particle number concentration positively correlated with the concentration of SO2, and negatively correlated with O3, whereas poorly correlated with NO2.

Lead in roadway dusts from different functional areas in a typical valley city, NW China: contamination and exposure risk.

PubMed

Pan, Huiyun; Lu, Xinwei; Lei, Kai

2018-01-01

Lead contamination and exposure risk assessment in roadway dusts from four different functional areas in a typical valley city in northwest China (Xi'an) were conducted in this study. A total of 130 roadway dust samples from park area (PA), traffic area (TA), educational area (EA), and residential area (RA) were collected and Pb concentrations in the samples were determined by using XRF (X-ray fluorescence). Geo-accumulation index (I geo ) and enrichment factor (EF) were applied to assess Pb contamination level and the hazard indexes (HI) of Pb were calculated to evaluate the exposure risks to children and adults. The results showed that roadway dusts from all four functional areas had elevated Pb concentrations and pollution characteristics of Pb were discrepant in different functional areas. The mean concentration of Pb in roadway dusts from PA, TA, EA, and RA was 147.4, 74.8, 119.6, and 161.0 mg kg -1 , respectively. The I geo and EF of Pb were mostly 1-3 and 2-20, which indicated moderate to high Pb contamination in roadway dusts. High contamination level of Pb in RA and EA should receive priority for prevention and control. Exposure risk assessment of Pb from roadway dusts was mainly in the acceptable range, but the potential risk of Pb exposure to children should be continuously concerned.

[Chromophoric dissolved organic matter absorption characteristics with relation to fluorescence in typical macrophyte, algae lake zones of Lake Taihu].

PubMed

Zhang, Yun-lin; Qin, Bo-qiang; Ma, Rong-hua; Zhu, Guang-wei; Zhang, Lu; Chen, Wei-min

2005-03-01

Chromophoric dissolved organic matter (CDOM) represents one of the primary light-absorbing species in natural waters and plays a critical in determining the aquatic light field. CDOM shows a featureless absorption spectrum that increases exponentially with decreasing wavelength, which limits the penetration of biologically damaging UV-B radiation (wavelength from 280 to 320 nm) in the water column, thus shielding aquatic organisms. CDOM absorption measurements and their relationship with dissolved organic carbon (DOC), and fluorescence are presented in typical macrophyte and algae lake zone of Lake Taihu based on a field investigation in April in 2004 and lab analysis. Absorption spectral of CDOM was measured from 240 to 800 nm using a Shimadzu UV-2401PC UV-Vis recording spectrophotometer. Fluorescence with an excitation wavelength of 355 nm, an emission wavelength of 450 nm is measured using a Shimadzu 5301 spectrofluorometer. Concentrations of DOC ranged from 6.3 to 17.2 mg/L with an average of 9.08 +/- 2.66 mg/L. CDOM absorption coefficients at 280 nm and 355 nm were in the range of 11.2 - 32.6 m(-1) (average 17.46m(-1) +/- 5.75 m(-1) and 2.4 - 8.3 m(-1) (average 4.17m(-1) +/- 1.47 m(-l)), respectively. The values of the DOC-specific absorption coefficient at 355 nm ranged from 0.31 to 0.64 L x (mg x m)-1. Fluorescence emission at 450 nm, excited at 355 nm, had a mean value of 1.32nm(-1) +/- 0.84 nm(-1). A significant lake zone difference is found in DOC concentration, CDOM absorption coefficient and fluorescence, but not in DOC-specific absorption coefficient and spectral slope coefficient. This regional distribution pattern is in agreement with the location of sources of yellow substance: highest concentrations close to river mouth under the influence of river inflow, lower values in East Lake Taihu. The values of algae lake zone are obvious larger than those of macrophyte lake zone. In Meiliang Bay, CDOM absorption, DOC concentration and fluorescence tend to decreasing from inside to mouth of the Bay. The results show a good correlation between CDOM absorption and DOC coefficients during 280 - 500 nm short wavelength intervals. The R-square coefficient between CDOM absorption and DOC concentration decreases with the increase of wavelength from 280 to 500 nm. The significant linear regression correlations between fluorescence, DOC concentration and absorption coefficients were found at 355 nm. The exponential slope coefficients ranged from 13.0 to 16.4 microm(-1) with a mean value 14.37microm(-1) +/- 0.73microm(-1), 17.3microm(-1) - 20.3microm(-1) with a mean value 19.17microm(-1) +/- 0.84microm(-1) and 12.0microm(-1) - 15.8microm(-1) with a mean value 13.38microm(-1) +/- 0.82microm(-1) over the 280 - 500 nm, 280 - 360 nm and 360 - 440 nm intervals.

Effects of self-aggregation on the hydration of an amphiphilic antidepressant drug in different aqueous media

NASA Astrophysics Data System (ADS)

Taboada, Pablo; Gutiérrez-Pichel, Manuel; Mosquera, Víctor

2004-03-01

Apparent molal volumes and adiabatic compressibilities of aqueous solutions of the amphiphilic antidepressant drug clomipramine hydrochloride have been determined from density and ultrasound velocity measurements in the temperature range 288.15-313.15 K in buffered aqueous solution of pH 3.0 and 5.5. Critical concentrations of aggregation of this drug were obtained from inflections on the plots of the sound velocity against drug concentration. Apparent molal adiabatic compressibilities of the aggregates formed by the drug, calculated by combining the ultrasound velocity and density data, were typical of those for a stacked aggregate. From the temperature dependence of the critical concentration and using the mass action model combined with the Phillips definition of the critical concentration the thermodynamic standard quantities: free Gibbs energy, enthalpy and entropy of aggregate formation were calculated. The critical concentration and energy involved in the aggregation process of this drug have been also evaluated experimentally using isothermal titration calorimetry at 298.15 K. The solvent-drug interactions have been discussed from compressibility and calorimetry data.

Extending the range of turbidity measurement using polarimetry

DOEpatents

Baba, Justin S.

2017-11-21

Turbidity measurements are obtained by directing a polarized optical beam to a scattering sample. Scattered portions of the beam are measured in orthogonal polarization states to determine a scattering minimum and a scattering maximum. These values are used to determine a degree of polarization of the scattered portions of the beam, and concentrations of scattering materials or turbidity can be estimated using the degree of polarization. Typically, linear polarizations are used, and scattering is measured along an axis that orthogonal to the direction of propagation of the polarized optical beam.

Atmospheric CH4 Concentrations from the Commonwealth Scientific and Industrial Research Organization (CSIRO) GASLAB Flask Sampling Network (1984 - 2001)

DOE Data Explorer

Steele, L. P. [Commonwealth Scientific and Industrial Research Organization (CSIRO), Aspendale, Victoria, Australia; Krummel, P. B. [Commonwealth Scientific and Industrial Research Organization (CSIRO), Aspendale, Victoria, Australia; Langenfelds, R. L. [Commonwealth Scientific and Industrial Research Organization (CSIRO), Aspendale, Victoria, Australia

2003-01-01

The listed data were obtained from flask air samples returned to the CSIRO GASLAB for analysis. Typical sample storage times ranged from days to weeks for some sites (e.g., Cape Grim) to as much as one year for Macquarie Island and the Antarctic sites. Experiments carried out to test for any change in sample CH4 mixing ratio during storage have shown no drift to within detection limits over test periods of several months to years (Cooper et al., 1999).

Recent progress in the development of MCT hot detectors

NASA Astrophysics Data System (ADS)

Wollrab, R.; Schirmacher, W.; Schallenberg, T.; Lutz, H.; Wendler, J.; Haiml, M.; Ziegler, J.

2017-11-01

To push HOT-performance, AIMs existing n-on-p technology has been improved by introducing Gold as an acceptor and reducing its concentration to the lower 1015/cm3 range as well as by optimizing the passivation process. This results in a substantial reduction in dark current density, a prerequisite for HOT operation. Recent dark current data are compared to ones previously obtained as well as to Tennant`s Rule07 [1], a generally accepted bench mark in this context. Furthermore, we present electro-optical parameters obtained in the temperature range from 120 K to 170 K on resulting FPAs with 640x512 pixels, a pitch of 15 μm and a typical (80 K) cutoff wavelength of 5.1 μm.

Concentration variance decay during magma mixing: a volcanic chronometer.

PubMed

Perugini, Diego; De Campos, Cristina P; Petrelli, Maurizio; Dingwell, Donald B

2015-09-21

The mixing of magmas is a common phenomenon in explosive eruptions. Concentration variance is a useful metric of this process and its decay (CVD) with time is an inevitable consequence during the progress of magma mixing. In order to calibrate this petrological/volcanological clock we have performed a time-series of high temperature experiments of magma mixing. The results of these experiments demonstrate that compositional variance decays exponentially with time. With this calibration the CVD rate (CVD-R) becomes a new geochronometer for the time lapse from initiation of mixing to eruption. The resultant novel technique is fully independent of the typically unknown advective history of mixing - a notorious uncertainty which plagues the application of many diffusional analyses of magmatic history. Using the calibrated CVD-R technique we have obtained mingling-to-eruption times for three explosive volcanic eruptions from Campi Flegrei (Italy) in the range of tens of minutes. These in turn imply ascent velocities of 5-8 meters per second. We anticipate the routine application of the CVD-R geochronometer to the eruptive products of active volcanoes in future in order to constrain typical "mixing to eruption" time lapses such that monitoring activities can be targeted at relevant timescales and signals during volcanic unrest.

Vertical distribution of trace-element concentrations and occurrence of metallurgical slag particles in accumulated bed sediments of Lake Roosevelt, Washington, September 2002

USGS Publications Warehouse

Cox, S.E.; Bell, P.R.; Lowther, J.S.; Van Metre, P.C.

2005-01-01

Sediment cores were collected from six locations in Lake Roosevelt to determine the vertical distributions of trace-element concentrations in the accumulated sediments of Lake Roosevelt. Elevated concentrations of arsenic, cadmium, copper, lead, mercury, and zinc occurred throughout much of the accumulated sediments. Concentrations varied greatly within the sediment core profiles, often covering a range of 5 to 10 fold. Trace-element concentrations typically were largest below the surficial sediments in the lower one-half of each profile, with generally decreasing concentrations from the 1964 horizon to the surface of the core. The trace-element profiles reflect changes in historical discharges of trace elements to the Columbia River by an upstream smelter. All samples analyzed exceeded clean-up guidelines adopted by the Confederated Tribes of the Colville Reservation for cadmium, lead, and zinc and more than 70 percent of the samples exceeded cleanup guidelines for mercury, arsenic, and copper. Although 100 percent of the samples exceeded sediment guidelines for cadmium, lead, and zinc, surficial concentrations of arsenic, copper, and mercury in some cores were less than the sediment-quality guidelines. With the exception of copper, the trace-element profiles of the five cores collected along the pre-reservoir Columbia River channel typically showed trends of decreasing concentrations in sediments deposited after the 1964 time horizon. The decreasing concentrations of trace elements in the upper half of cores from along the pre-reservoir Columbia River showed a pattern of decreasing concentrations similar to reductions in trace-element loading in liquid effluent from an upstream smelter. Except for arsenic, trace-element concentrations typically were smaller at downstream reservoir locations along the pre-reservoir Columbia River. Trace-element concentration in sediments from the Spokane Arm of the reservoir showed distinct differences compared to the similarities observed in cores from along the pre-reservoir Columbia River. Particles of slag, which have physical and chemical characteristics of slag discharged to the Columbia River by a lead-zinc smelter upstream of the reservoir at Trail, British Columbia, were found in sediments of Lake Roosevelt. Slag particles are more common in the upstream reaches of the reservoir. The chemical composition of the interior matrix of slag collected from Lake Roosevelt closely approximated the reported elemental concentrations of fresh smelter slag, although evidence of slag weathering was observed. Exfoliation flakes were observed on the surface of weathered slag particles isolated from the core sediments. The concentrations of zinc on the exposed surface of slag grains were smaller than concentrations on interior surfaces. Weathering rinds also were observed in the cross section of weathered slag grains, indicating that the glassy slag material was undergoing hydration and chemical weathering. Trace elements observed in accumulated sediments in the middle and lower reaches of the reservoir are more likely due to the input from liquid effluent discharges compared to slag discharges from the upstream smelter.

Cardiovascular magnetic resonance demonstration of the spectrum of morphological phenotypes and patterns of myocardial scarring in Anderson-Fabry disease.

PubMed

Deva, Djeven Parameshvara; Hanneman, Kate; Li, Qin; Ng, Ming Yen; Wasim, Syed; Morel, Chantal; Iwanochko, Robert M; Thavendiranathan, Paaladinesh; Crean, Andrew Michael

2016-03-31

Although it is known that Anderson-Fabry Disease (AFD) can mimic the morphologic manifestations of hypertrophic cardiomyopathy (HCM) on echocardiography, there is a lack of cardiovascular magnetic resonance (CMR) literature on this. There is limited information in the published literature on the distribution of myocardial fibrosis in patients with AFD, with scar reported principally in the basal inferolateral midwall. All patients with confirmed AFD undergoing CMR at our center were included. Left ventricular (LV) volumes, wall thicknesses and scar were analyzed offline. Patients were categorized into 4 groups: (1) no wall thickening; (2) concentric hypertrophy; (3) asymmetric septal hypertrophy (ASH); and (4) apical hypertrophy. Charts were reviewed for clinical information. Thirty-nine patients were included (20 males [51%], median age 45.2 years [range 22.3-64.4]). Almost half (17/39) had concentric wall thickening. Almost half (17/39) had pathologic LV scar; three quarters of these (13/17) had typical inferolateral midwall scar. A quarter (9/39) had both concentric wall thickening and typical inferolateral scar. A subgroup with ASH and apical hypertrophy (n = 5) had greater maximum wall thickness, total LV scar, apical scar and mid-ventricular scar than those with concentric hypertrophy (n = 17, p < 0.05). Patients with elevated LVMI had more overall arrhythmia (p = 0.007) more ventricular arrhythmia (p = 0.007) and sustained ventricular tachycardia (p = 0.008). Concentric thickening and inferolateral mid-myocardial scar are the most common manifestations of AFD, but the spectrum includes cases morphologically identical to apical and ASH subtypes of HCM and these have more apical and mid-ventricular LV scar. Significant LVH is associated with ventricular arrhythmia.

Determination of lipid oxidation products in vegetable oils and marine omega-3 supplements.

PubMed

Halvorsen, Bente Lise; Blomhoff, Rune

2011-01-01

There is convincing evidence that replacing dietary saturated fats with polyunsaturated fats (PUFA) decreases risk of cardiovascular diseases. Therefore, PUFA rich foods such as vegetable oils, fatty fish, and marine omega-3 supplements are recommended. However, PUFA are easily oxidizable and there is concern about possible negative health effects from intake of oxidized lipids. Little is known about the degree of lipid oxidation in such products. To assess the content of lipid oxidation products in a large selection of vegetable oils and marine omega-3 supplements available in Norway. Both fresh and heated vegetable oils were studied. A large selection of commercially available vegetable oils and marine omega-3 supplements was purchased from grocery stores, pharmacies, and health food stores in Norway. The content of lipid oxidation products were measured as peroxide value and alkenal concentration. Twelve different vegetable oils were heated for a temperature (225°C) and time (25 minutes) resembling conditions typically used during cooking. The peroxide values were in the range 1.04-10.38 meq/kg for omega-3 supplements and in the range 0.60-5.33 meq/kg for fresh vegetable oils. The concentration range of alkenals was 158.23-932.19 nmol/mL for omega-3 supplements and 33.24-119.04 nmol/mL for vegetable oils. After heating, a 2.9-11.2 fold increase in alkenal concentration was observed for vegetable oils. The contents of hydroperoxides and alkenals in omega-3 supplements are higher than in vegetable oils. After heating vegetable oils, a large increase in alkenal concentration was observed.

Differential Effects of Various Typical and Atypical Antipsychotics on Plasma Glucose and Insulin Levels in the Mouse: Evidence for the Involvement of Sympathetic Regulation

PubMed Central

Savoy, Yvette E.; Ashton, Michael A.; Miller, Matthew W.; Nedza, Frank M.; Spracklin, Douglas K.; Hawthorn, Mark H.; Rollema, Hans; Matos, F. Fatima; Hajos-Korcsok, Eva

2010-01-01

Atypical antipsychotic treatment has been associated with serious metabolic adverse events, such as glucose dysregulation and development of type 2 diabetes. As part of our studies on possible underlying mechanisms, we investigated the acute effects of various typical and atypical antipsychotics on plasma glucose and insulin in FVB/N mice, a strain that showed a more pronounced hyperglycemic response to clozapine than C57BL/6 and CD-1 mice. Acute administration of high doses of clozapine, olanzapine, quetiapine, perphenazine, or chlorpromazine significantly increased plasma glucose by 100%–140% above basal levels without significant effects on insulin levels. In contrast, risperidone reduced plasma glucose (−30%) and markedly enhanced plasma insulin levels. Doses of ziprasidone that gave 50-fold higher free plasma concentrations than therapeutic plasma levels, as well as high doses of aripiprazole and haloperidol, did not significantly alter either glucose or insulin levels. Clozapine- and olanzapine-induced hyperglycemia occurred at free plasma concentrations that were within, or one order of magnitude above, the range of therapeutic plasma levels. Pretreatment with either the ganglionic blocker hexamethonium, or the α2 adrenergic receptor antagonist yohimbine, blocked the clozapine- and chlorpromazine-induced increase in glucose levels. Taken together, these results suggest that typical and atypical antipsychotics with known metabolic liability produce acute hyperglycemia in mice and that this effect is likely driven by activation of the sympathetic autonomic nervous system via a central mechanism. PMID:18703666

Paramagnetic Attraction of Impurity-Helium Solids

NASA Technical Reports Server (NTRS)

Bernard, E. P.; Boltnev, R. E.; Khmelenko, V. V.; Lee, D. M.

2003-01-01

Impurity-helium solids are formed when a mixture of impurity and helium gases enters a volume of superfluid helium. Typical choices of impurity gas are hydrogen deuteride, deuterium, nitrogen, neon and argon, or a mixture of these. These solids consist of individual impurity atoms and molecules as well as clusters of impurity atoms and molecules covered with layers of solidified helium. The clusters have an imperfect crystalline structure and diameters ranging up to 90 angstroms, depending somewhat on the choice of impurity. Immediately following formation the clusters aggregate into loosely connected porous solids that are submerged in and completely permeated by the liquid helium. Im-He solids are extremely effective at stabilizing high concentrations of free radicals, which can be introduced by applying a high power RF dis- charge to the impurity gas mixture just before it strikes the super fluid helium. Average concentrations of 10(exp 19) nitrogen atoms/cc and 5 x 10(exp 18) deuterium atoms/cc can be achieved this way. It shows a typical sample formed from a mixture of atomic and molecular hydrogen and deuterium. It shows typical sample formed from atomic and molecular nitrogen. Much of the stability of Im-He solids is attributed to their very large surface area to volume ratio and their permeation by super fluid helium. Heat resulting from a chance meeting and recombination of free radicals is quickly dissipated by the super fluid helium instead of thermally promoting the diffusion of other nearby free radicals.

Under What Conditions Can Equilibrium Gas-Particle Partitioning Be Expected to Hold in the Atmosphere?

PubMed

Mai, Huajun; Shiraiwa, Manabu; Flagan, Richard C; Seinfeld, John H

2015-10-06

The prevailing treatment of secondary organic aerosol formation in atmospheric models is based on the assumption of instantaneous gas-particle equilibrium for the condensing species, yet compelling experimental evidence indicates that organic aerosols can exhibit the properties of highly viscous, semisolid particles, for which gas-particle equilibrium may be achieved slowly. The approach to gas-particle equilibrium partitioning is controlled by gas-phase diffusion, interfacial transport, and particle-phase diffusion. Here we evaluate the controlling processes and the time scale to achieve gas-particle equilibrium as a function of the volatility of the condensing species, its surface accommodation coefficient, and its particle-phase diffusivity. For particles in the size range of typical atmospheric organic aerosols (∼50-500 nm), the time scale to establish gas-particle equilibrium is generally governed either by interfacial accommodation or particle-phase diffusion. The rate of approach to equilibrium varies, depending on whether the bulk vapor concentration is constant, typical of an open system, or decreasing as a result of condensation into the particles, typical of a closed system.

Dietary uptake of polychlorinated biphenyls (PCBs) by rainbow trout

USGS Publications Warehouse

Carline, Robert F.; Barry, Patrick M.; Ketola, H. George

2004-01-01

The presence of detectable levels of polychlorinated biphenyls (PCBs) in commercially produced fish feed has raised a concern about the degree of biomagnification of these contaminants in hatchery-reared trout. Our objectives were to (1) define the relationship between concentrations of PCBs in fish feed and in fish tissue and (2) estimate the relative contributions of feed and hatchery supply water to PCB concentrations in fish. We conducted a 6-month feeding trial with fingerling rainbow trout Oncorhynchus mykiss fed commercial diets with four concentrations of PCBs: a low-PCB diet (69 ng/g); a typical commercial diet (126 ng/g); and the typical diet spiked with PCBs at two levels (220 and 280 ng/g). The concentrations of PCBs in fillets after 1 month were commensurate with those in the feeds and remained relatively stable for the next 5 months; mean PCB concentrations in fillets ranged from 54 to 94 ng/g. Low levels of PCBs were detected in the hatchery supply water. We used the concentrations of PCBs in the feeds, absorption rates of PCBs, and two different rates of PCB depuration to estimate the potential uptake of PCBs from supply water. When we used a low depuration rate (half-life = 219 d), the computed body burdens of PCBs could be entirely attributed to the feeds. When a high depuration rate (half-life = 66 d) was used, some uptake of PCBs from the supply water was likely, but most of the total body burden originated from the feeds. We concluded that rainbow trout fed a diet with 126 ng/g PCBs would have a PCB concentration of about 60 ng/g in their fillets, which is high enough to warrant issuance of a consumption advisory (no more than one meal of fish per week) under a protocol adopted by some Great Lakes states.

Current and historical concentrations of poly and perfluorinated compounds in sediments of the northern Great Lakes - Superior, Huron, and Michigan.

PubMed

Codling, Garry; Hosseini, Soheil; Corcoran, Margaret B; Bonina, Solidea; Lin, Tian; Li, An; Sturchio, Neil C; Rockne, Karl J; Ji, Kyunghee; Peng, Hui; Giesy, John P

2018-05-01

Current and historical concentrations of 22 poly- and perfluorinated compounds (PFASs) in sediment collected from Lake Superior and northern Lake Michigan in 2011 and Lake Huron in 2012 are reported. The sampling was performed in two ways, Ponar grabs of surface sediments for current spatial distribution across the lake and dated cores for multi-decadal temporal trends. Mean concentrations of the sum of PFASs (∑PFASs) were 1.5, 4.6 and 3.1 ng g -1 dry mas (dm) in surface sediments for Lakes Superior, Michigan and Huron, respectively. Of the five Laurentian Lakes, the watersheds of Superior and Huron are the less densely populated by humans, and concentrations observed were typically less and from more diffuse sources, due to lesser urbanization and industrialization. However, some regions of greater concentrations were observed and might indicate more local, point sources. In core samples concentrations ranged from 7 that include perfluoro-n-octane sulfonate (PFOS) bind more strongly to sediment, which resulted in more accurate analyses of temporal trends. Shorter-chain PFASs, such as perfluoro-n-butanoic acid which is the primary replacement for C8 PFASs that have been phased out, are more soluble and were identified in some core layers at depths corresponding to pre-production periods. Thus, analyses of temporal trends of these more soluble compounds in cores of sediments were less accurate. Total elemental fluorine (TF) and extractable organic fluorine (EOF) indicated that identified PFASs were not a significant fraction of fluorine containing compounds in sediment (<0.01% in EOF). Copyright © 2018 Elsevier Ltd. All rights reserved.

Impacts of aircraft deicer and anti-icer runoff on receiving waters from Dallas/Fort Worth International Airport, Texas, U.S.A.

PubMed

Corsi, Steven R; Harwell, Glenn R; Geis, Steven W; Bergman, Daniel

2006-11-01

From October 2002 to April 2004, data were collected from Dallas/Fort Worth (DFW) International Airport (TX, U.S.A.) outfalls and receiving waters (Trigg Lake and Big Bear Creek) to document the magnitude and potential effects of aircraft deicer and anti-icer fluid (ADAF) runoff on water quality. Glycol concentrations at outfalls ranged from less than 18 to 23,800 mg/L, whereas concentrations in Big Bear Creek were less because of dilution, dispersion, and degradation, ranging from less than 18 to 230 mg/L. Annual loading results indicate that 10 and 35% of what was applied to aircraft was discharged to Big Bear Creek in 2003 and 2004, respectively. Glycol that entered Trigg Lake was diluted and degraded before reaching the lake outlet. Dissolved oxygen (DO) concentrations at airport outfalls sometimes were low (<2.0 mg/L) but typical of what was measured in an urban reference stream. In comparison, the DO concentration at Trigg Lake monitoring sites was consistently greater than 5.5 mg/L during the monitoring period, probably because of the installation of aerators in the lake by DFW personnel. The DO concentration in Big Bear Creek was very similar at sites upstream and downstream of airport influence (>5.0 mg/L). Results of toxicity tests indicate that effects on Ceriodaphnia dubia, Pimephales promelas, and Selanastrum capricornutum are influenced by type IV ADAF (anti-icer), not just type I ADAF (deicer) as is more commonly assumed.

Concentration and Risk Evaluation of Polycyclic Aromatic Hydrocarbons in Urban Soil in the Typical Semi-Arid City of Xi’an in Northwest China

PubMed Central

Wang, Lijun; Zhang, Shengwei; Wang, Li; Zhang, Wenjuan; Shi, Xingmin; Lu, Xinwei; Li, Xiaoping; Li, Xiaoyun

2018-01-01

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants, presenting potential threats to the ecological environment and human health. Sixty-two urban soil samples were collected in the typical semi-arid city of Xi’an in Northwest China. They were analyzed for concentration, pollution, and ecological and health risk of sixteen U.S. Environmental Protection Agency priority PAHs. The total concentrations of the sixteen PAHs (Σ16PAHs) in the urban soil ranged from 390.6 to 10,652.8 µg/kg with an average of 2052.6 µg/kg. The concentrations of some individual PAHs in the urban soil exceeded Dutch Target Values of Soil Quality and the Σ16PAHs represented heavy pollution. Pyrene and dibenz[a,h]anthracene had high ecological risk to aquatic/soil organisms, while other individual PAHs showed low ecological risk. The total ecological risk of PAHs to aquatic/soil organisms is classified as moderate. Toxic equivalency quantities (TEQs) of the sixteen PAHs varied between 21.16 and 1625.78 µg/kg, with an average of 423.86 µg/kg, indicating a relatively high toxicity potential. Ingestion and dermal adsorption of soil dust were major pathways of human exposure to PAHs from urban soil. Incremental lifetime cancer risks (ILCRs) of human exposure to PAHs were 2.86 × 10−5 for children and 2.53 × 10−5 for adults, suggesting that the cancer risk of human exposure to PAHs from urban soil is acceptable. PMID:29584654

Arsenic contamination of natural waters in San Juan and La Pampa, Argentina.

PubMed

O'Reilly, J; Watts, M J; Shaw, R A; Marcilla, A L; Ward, N I

2010-12-01

Arsenic (As) speciation in surface and groundwater from two provinces in Argentina (San Juan and La Pampa) was investigated using solid phase extraction (SPE) cartridge methodology with comparison to total arsenic concentrations. A third province, Río Negro, was used as a control to the study. Strong cation exchange (SCX) and strong anion exchange (SAX) cartridges were utilised in series for the separation and preservation of arsenite (As(III)), arsenate (As(V)), monomethylarsonic acid (MA(V)) and dimethylarsinic acid (DMA(V)). Samples were collected from a range of water outlets (rivers/streams, wells, untreated domestic taps, well water treatment works) to assess the relationship between total arsenic and arsenic species, water type and water parameters (pH, conductivity and total dissolved solids, TDS). Analysis of the waters for arsenic (total and species) was performed by inductively coupled plasma mass spectrometry (ICP-MS) in collision cell mode. Total arsenic concentrations in the surface and groundwater from Encon and the San José de Jáchal region of San Juan (north-west Argentina within the Cuyo region) ranged from 9 to 357 μg l(-1) As. Groundwater from Eduardo Castex (EC) and Ingeniero Luiggi (LU) in La Pampa (central Argentina within the Chaco-Pampean Plain) ranged from 3 to 1326 μg l(-1) As. The pH range for the provinces of San Juan (7.2-9.7) and La Pampa (7.0-9.9) are in agreement with other published literature. The highest total arsenic concentrations were found in La Pampa well waters (both rural farms and pre-treated urban sources), particularly where there was high pH (typically > 8.2), conductivity (>2,600 μS cm(-1)) and TDS (>1,400 mg l(-1)). Reverse osmosis (RO) treatment of well waters in La Pampa for domestic drinking water in EC and LU significantly reduced total arsenic concentrations from a range of 216-224 μg l(-1) As to 0.3-0.8 μg l(-1) As. Arsenic species for both provinces were predominantly As(III) and As(V). As(III) and As(V) concentrations in San Juan ranged from 4-138 μg l(-1) to <0.02-22 μg l(-1) for surface waters (in the San José de Jáchal region) and 23-346 μg l(-1) and 0.04-76 μg l(-1) for groundwater, respectively. This translates to a relative As(III) abundance of 69-100% of the total arsenic in surface waters and 32-100% in groundwater. This is unexpected because it is typically thought that in oxidising conditions (surface waters), the dominant arsenic species is As(V). However, data from the SPE methodology suggests that As(III) is the prevalent species in San Juan, indicating a greater influence from reductive processes. La Pampa groundwater had As(III) and As(V) concentrations of 5-1,332 μg l(-1) and 0.09-592 μg l(-1) for EC and 32-242 μg l(-1) and 30-277 μg l(-1) As for LU, respectively. Detectable levels of MA(V) were reported in both provinces up to a concentration of 79 μg l(-1) (equating to up to 33% of the total arsenic). Previously published literature has focused primarily on the inorganic arsenic species, however this study highlights the potentially significant concentrations of organoarsenicals present in natural waters. The potential for separating and preserving individual arsenic species in the field to avoid transformation during transport to the laboratory, enabling an accurate assessment of in situ arsenic speciation in water supplies is discussed.

[PBDEs pollution in the atmosphere of a typical E-waste dismantling region].

PubMed

Chen, Duo-hong; Li, Li-ping; Bi, Xin-hui; Zhao, Jin-ping; Sheng, Guo-ying; Fu, Jia-mo

2008-08-01

The vapor-phase and particulate-phase samples were collected from the E-waste dismantling region (E) and a reference region (S), which is located in the upwind direction of the E and where the costume industry is developed. The aim was to acquire information about the concentrations, gas/particle partitioning and distribution of polybrominated diphenyt ethers (PBDEs). 11 congeners PBDEs were detected with GC-NCI-MS. The results showed that E-waste dismantling has resulted in serious pollution and the PBDE concentrations (from tri-to deca-BDE) ranged from 51.1 pg x m(-3) to 2685 pg x m(-3) (mean:830 pg x m(-3)), while the PBDE concentrations (from tri-to deca-BDE) in S were in the range of 1.00 pg x m(-3) to 98.9 pg x m(-3) (mean: 28.7 pg x m(-3)). The gas/particle partitioning of PBDEs exhibited a strong dependence on bromine number. Low-brominated PBDEs tend to have a higher concentration in the gas-phase while highly brominated PBDEs are mostly associated with the particulate. The mass distribution of PBDEs in E (including vapor-phase and particulate-phase) was dominated by penta-BDE, accounting for 54.3% of the total PBDEs, followed by deca-BDE, accounting for 23.8%. This pollution characters validated that the E-waste did not only come from Asia, but also from North America and Europe.

Molecular dynamics simulations of the electrical double layer on smectite surfaces contacting concentrated mixed electrolyte (NaCl-CaCl2) solutions.

PubMed

Bourg, Ian C; Sposito, Garrison

2011-08-15

We report new molecular dynamics results elucidating the structure of the electrical double layer (EDL) on smectite surfaces contacting mixed NaCl-CaCl(2) electrolyte solutions in the range of concentrations relevant to pore waters in geologic repositories for CO(2) or high-level radioactive waste (0.34-1.83 mol(c) dm(-3)). Our results confirm the existence of three distinct ion adsorption planes (0-, β-, and d-planes), often assumed in EDL models, but with two important qualifications: (1) the location of the β- and d-planes are independent of ionic strength or ion type and (2) "indifferent electrolyte" ions can occupy all three planes. Charge inversion occurred in the diffuse ion swarm because of the affinity of the clay surface for CaCl(+) ion pairs. Therefore, at concentrations ≥0.34 mol(c) dm(-3), properties arising from long-range electrostatics at interfaces (electrophoresis, electro-osmosis, co-ion exclusion, colloidal aggregation) will not be correctly predicted by most EDL models. Co-ion exclusion, typically neglected by surface speciation models, balanced a large part of the clay mineral structural charge in the more concentrated solutions. Water molecules and ions diffused relatively rapidly even in the first statistical water monolayer, contradicting reports of rigid "ice-like" structures for water on clay mineral surfaces. Published by Elsevier Inc.

Rapid measurement of perchlorate in polar ice cores down to sub-ng L(-1) levels without pre-concentration.

PubMed

Peterson, Kari; Cole-Dai, Jihong; Brandis, Derek; Cox, Thomas; Splett, Scott

2015-10-01

An ion chromatography-electrospray ionization-tandem mass spectrometry (IC-ESI-MS/MS) method has been developed for rapid and accurate measurement of perchlorate in polar snow and ice core samples in which perchlorate concentrations are expected to be as low as 0.1 ng L(-1). Separation of perchlorate from major inorganic species in snow is achieved with an ion chromatography system interfaced to an AB SCIEX triple quadrupole mass spectrometer operating in multiple reaction monitoring mode. Under optimized conditions, the limit of detection and lower limit of quantification without pre-concentration have been determined to be 0.1 and 0.3 ng L(-1), respectively, with a linear dynamic range of 0.3-10.0 ng L(-1) in routine measurement. These represent improvements over previously reported methods using similar analytical techniques. The improved method allows fast, accurate, and reproducible perchlorate quantification down to the sub-ng L(-1) level and will facilitate perchlorate measurement in the study of natural perchlorate production with polar ice cores in which perchlorate concentrations are anticipated to vary in the low and sub-ng L(-1) range. Initial measurements of perchlorate in ice core samples from central Greenland show that typical perchlorate concentrations in snow dated prior to the Industrial Revolution are about 0.8 ng L(-1), while perchlorate concentrations are significantly higher in recent (post-1980) snow, suggesting that anthropogenic sources are a significant contributor to perchlorate in the current environment.

Observation of small cluster formation in concentrated monoclonal antibody solutions and its implications to solution viscosity.

PubMed

Yearley, Eric J; Godfrin, Paul D; Perevozchikova, Tatiana; Zhang, Hailiang; Falus, Peter; Porcar, Lionel; Nagao, Michihiro; Curtis, Joseph E; Gawande, Pradad; Taing, Rosalynn; Zarraga, Isidro E; Wagner, Norman J; Liu, Yun

2014-04-15

Monoclonal antibodies (mAbs) are a major class of biopharmaceuticals. It is hypothesized that some concentrated mAb solutions exhibit formation of a solution phase consisting of reversibly self-associated aggregates (or reversible clusters), which is speculated to be responsible for their distinct solution properties. Here, we report direct observation of reversible clusters in concentrated solutions of mAbs using neutron spin echo. Specifically, a stable mAb solution is studied across a transition from dispersed monomers in dilute solution to clustered states at more concentrated conditions, where clusters of a preferred size are observed. Once mAb clusters have formed, their size, in contrast to that observed in typical globular protein solutions, is observed to remain nearly constant over a wide range of concentrations. Our results not only conclusively establish a clear relationship between the undesirable high viscosity of some mAb solutions and the formation of reversible clusters with extended open structures, but also directly observe self-assembled mAb protein clusters of preferred small finite size similar to that in micelle formation that dominate the properties of concentrated mAb solutions. Copyright © 2014 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Understanding the Effects of Diet on Larval Crassostrea virginica: A Comparison of Commercial Concentrates and Live Algal Feed

NASA Astrophysics Data System (ADS)

Williams, C. T.; Krause, J. W.; Walton, W. C.

2016-02-01

Traditionally shellfish hatcheries produce live microalgal cultures to feed larvae. This process is time consuming, labor intensive, expensive, and requires a large and sterile environment. The use of commercial microalgal concentrates allows hatcheries to reduce operational costs and optimize floor space; however, there have been no systematic studies examining the relative yields from live algal vs. concentrate-based diets. The effects of diet type on the growth-rate, survival, and settling efficiency of Crassostrea virginica were explored by varying diet proportions in two-day old spawned larvae through metamorphosis and settlement. Live microalgal feed was blended from axenic Isochrysis, Tetraselmis, Pavlova, and Chaetoceros cultures to mimic typical hatchery recipes. The live microalgae was supplemented with variable amounts of the concentrate, Reed Mariculture Shellfish Diet 1800™, across multiple treatments ranging from 100% concentrate vs. 100% live diet. Caloric content was used to normalize between the diet types to achieve treatments with 25, 50 and 75% live diet supplemented with proportional amounts of concentrate (e.g. 75, 50, and 25% concentrate, respectively). The goal of this method was to show whether survival and settling rates depend on the proportion of live microalgal diet. Such data will inform a cost-benefit analysis of whether concentrates are a financially viable alternative for oyster hatcheries.

Improved product energy intensity benchmarking metrics for thermally concentrated food products.

PubMed

Walker, Michael E; Arnold, Craig S; Lettieri, David J; Hutchins, Margot J; Masanet, Eric

2014-10-21

Product energy intensity (PEI) metrics allow industry and policymakers to quantify manufacturing energy requirements on a product-output basis. However, complexities can arise for benchmarking of thermally concentrated products, particularly in the food processing industry, due to differences in outlet composition, feed material composition, and processing technology. This study analyzes tomato paste as a typical, high-volume concentrated product using a thermodynamics-based model. Results show that PEI for tomato pastes and purees varies from 1200 to 9700 kJ/kg over the range of 8%-40% outlet solids concentration for a 3-effect evaporator, and 980-7000 kJ/kg for a 5-effect evaporator. Further, the PEI for producing paste at 31% outlet solids concentration in a 3-effect evaporator varies from 13,000 kJ/kg at 3% feed solids concentration to 5900 kJ/kg at 6%; for a 5-effect evaporator, the variation is from 9200 kJ/kg at 3%, to 4300 kJ/kg at 6%. Methods to compare the PEI of different product concentrations on a standard basis are evaluated. This paper also presents methods to develop PEI benchmark values for multiple plants. These results focus on the case of a tomato paste processing facility, but can be extended to other products and industries that utilize thermal concentration.

Water Quality and Evaluation of Pesticides in Lakes in the Ridge Citrus Region of Central Florida

USGS Publications Warehouse

Choquette, Anne F.; Kroening, Sharon E.

2009-01-01

Water chemistry, including major inorganic constituents, nutrients, and pesticide compounds, was compared between seven lakes surrounded by citrus agriculture and an undeveloped lake on the Lake Wales Ridge (herein referred to as the Ridge) in central Florida. The region has been recognized for its vulnerability to the leaching of agricultural chemicals into the subsurface due to factors including soils, climate, and land use. About 40 percent of Florida's citrus cultivation occurs in 'ridge citrus' areas characterized by sandy well drained soils, with the remainder in 'flatwoods citrus' characterized by high water tables and poorly drained soils. The lakes on the Ridge are typically flow-through lakes that exchange water with adjacent and underlying aquifer systems. This study is the first to evaluate the occurrence of pesticides in lakes on the Ridge, and also represents one of the first monitoring efforts nationally to focus on regional-scale assessment of current-use pesticides in small- to moderate-sized lakes (5 to 393 acres). The samples were collected between December 2003 and September 2005. The lakes in citrus areas contained elevated concentrations of major inorganic constituents (including alkalinity, total dissolved solids, calcium, magnesium, sodium, potassium, chloride, and sulfate), total nitrogen, pH, and pesticides compared to the undeveloped lake. Nitrate (as N) and total nitrogen concentrations were typically elevated in the citrus lakes, with maximum values of 4.70 and 5.19 mg/L (milligrams per liter), respectively. Elevated concentrations of potassium, nitrate, and other inorganic constituents in the citrus lakes likely reflect inputs from the surficial ground-water system that originated predominantly from agricultural fertilizers, soil amendments, and inorganic pesticides. A total of 20 pesticide compounds were detected in the lakes, of which 12 compounds exceeded the standardized reporting level of 0.06 ug/L (microgram per liter). Those most frequently detected above the 0.06-ug/L level were aldicarb sulfoxide, diuron, simazine degradates hydroxysimazine and didealkylatrazine (DDA), bromacil, norflurazon, and demethyl norflurazon which occurred at detection rates ranging from 25 to 86 percent of samples, respectively. Typically, pesticide concentrations in the lake samples were less than 1 microgram per liter. The number of targeted pesticide compounds detected per lake in the citrus areas ranged from 9 to 14 compared to 3 compounds detected at trace levels in the undeveloped lake. Consistent detections of parents and degradates in quarterly samples indicated the presence of pesticide compounds in the lakes many months or years (for example, bromacil) after their application, signaling the persistence of some pesticide compounds in the lakes and/or ground-water systems. Pesticide degradate concentrations frequently exceeded parent concentrations in the lakes. This study was the first in the Ridge citrus region to analyze for glyphosate - widely used in citrus - and its degradate aminomethylphosphonic acid (AMPA), neither of which were detected, as well as a number of triazine degradates, including hydroxysimazine, which were detected. The lake pesticide concentrations did not exceed current Federal aquatic-life benchmarks, available for 10 of the 20 detected pesticide compounds. Limited occurrences of bromacil, diuron, or norflurazon concentrations were within about 10 to 90 percent of benchmark guidelines for acute effects on nonvascular aquatic plants in one or two of the lakes. The lake pesticide concentrations for several targeted pesticides were relatively high compared to corresponding national stream-water percentiles, which is consistent with this region's vulnerability for pesticide leaching into water resources. Several factors were evaluated to gain insight into the processes controlling pesticide transport and fate, and to assess their utility for estimating th

Testing short-range migration of microbial methane as a hydrate formation mechanism: Results from Andaman Sea and Kumano Basin drill sites and global implications

NASA Astrophysics Data System (ADS)

Malinverno, Alberto; Goldberg, David S.

2015-07-01

Methane gas hydrates in marine sediments often concentrate in coarse-grained layers surrounded by fine-grained marine muds that are hydrate-free. Methane in these hydrate deposits is typically microbial, and must have migrated from its source as the coarse-grained sediments contain little or no organic matter. In "long-range" migration, fluid flow through permeable layers transports methane from deeper sources into the gas hydrate stability zone (GHSZ). In "short-range" migration, microbial methane is generated within the GHSZ in fine-grained sediments, where small pore sizes inhibit hydrate formation. Dissolved methane can then diffuse into adjacent sand layers, where pore size does not restrict hydrate formation and hydrates can accumulate. Short-range migration has been used to explain hydrate accumulations in sand layers observed in drill sites on the northern Cascadia margin and in the Gulf of Mexico. Here we test the feasibility of short-range migration in two additional locations, where gas hydrates have been found in coarse-grained volcanic ash layers (Site NGHP-01-17, Andaman Sea, Indian Ocean) and turbidite sand beds (Site IODP-C0002, Kumano forearc basin, Nankai Trough, western Pacific). We apply reaction-transport modeling to calculate dissolved methane concentration and gas hydrate amounts resulting from microbial methane generated within the GHSZ. Model results show that short-range migration of microbial methane can explain the overall amounts of methane hydrate observed at the two sites. Short-range migration has been shown to be feasible in diverse margin environments and is likely to be a widespread methane transport mechanism in gas hydrate systems. It only requires a small amount of organic carbon and sediment sequences consisting of thin coarse-grained layers that can concentrate microbial methane generated within thick fine-grained sediment beds; these conditions are common along continental margins around the globe.

Pesticides and nitrate in groundwater underlying citrus croplands, Lake Wales Ridge, central Florida, 1999-2005.

USGS Publications Warehouse

Choquette, Anne F.

2014-01-01

This report summarizes pesticide and nitrate (as nitrogen) results from quarterly sampling of 31 surficial-aquifer wells in the Lake Wales Ridge Monitoring Network during April 1999 through January 2005. The wells, located adjacent to citrus orchards and used for monitoring only, were generally screened (sampled) within 5 to 40 feet of the water table. Of the 44 citrus pesticides and pesticide degradates analyzed, 17 were detected in groundwater samples. Parent pesticides and degradates detected in quarterly groundwater samples, ordered by frequency of detection, included norflurazon, demethyl norflurazon, simazine, diuron, bromacil, aldicarb sulfone, aldicarb sulfoxide, deisopropylatrazine (DIA), imidacloprid, metalaxyl, thiazopyr monoacid, oxamyl, and aldicarb. Reconnaissance sampling of five Network wells yielded detection of four additional pesticide degradates (hydroxysimazine, didealkylatrazine, deisopropylhydroxyatrazine, and hydroxyatrazine). The highest median concentration values per well, based on samples collected during the 1999–2005 period (n=14 to 24 samples per well), included 3.05 µg/L (micrograms per liter) (simazine), 3.90 µg/L (diuron), 6.30 µg/L (aldicarb sulfone), 6.85 µg/L (aldicarb sulfoxide), 22.0 µg/L (demethyl norflurazon), 25.0 µg/ (norflurazon), 89 µg/ (bromacil), and 25.5 mg/L (milligrams per liter) (nitrate). Nitrate concentrations exceeded the 10 mg/L (as nitrogen) drinking water standard in one or more groundwater samples from 28 of the wells, and the median nitrate concentration among these wells was 14 mg/L. Sampled groundwater pesticide concentrations exceeded Florida’s health-guidance benchmarks for aldicarb sulfoxide and aldicarb sulfone (4 wells), the sum of aldicarb and its degradates (6 wells), simazine (2 wells), the sum of simazine and DIA (3 wells), diuron (2 wells), bromacil (1 well), and the sum of norflurazon and demethyl norflurazon (1 well). The magnitude of fluctuations in groundwater pesticide concentrations varied between wells and between pesticide compounds. Of the 10 pesticide compounds detected at sufficient frequency to assess temporal variability in quarterly sampling records, median values of the relative interquartile range (ratio of the interquartile range to the median) among wells typically ranged from about 100 to 150 percent. The relative interquartile range of pesticide concentrations at individual wells could be much higher, sometimes exceeding 200 to 500 percent. No distinct spatial patterns were apparent among median pesticide concentrations in sampled wells; nitrate concentrations tended to be greater in samples from wells in the northern part of the study area.

Routine determination of sulfonylurea, imidazolinone, and sulfonamide herbicides at nanogram-per-liter concentrations by solid-phase extraction and liquid chromatography/mass spectrometry

USGS Publications Warehouse

Furlong, E.T.; Burkhardt, M.R.; Gates, Paul M.; Werner, S.L.; Battaglin, W.A.

2000-01-01

Sulfonylurea (SU), imidazolinone (IMI), and sulfonamide (SA) herbicides are new classes of low-application-rate herbicides increasingly used by farmers. Some of these herbicides affect both weed and crop species at low dosages and must be carefully used. Less is known about the effect of these compounds on non-crop plant species, but a concentration of 100 ng/l in water has been proposed as the threshold for possible plant toxicity for most of these herbicides. Hence, analytical methods must be capable of detecting SUs, IMIs, and SAs at concentrations less than 100 ng/l in ambient water samples. The authors developed a two-cartridge, solid-phase extraction method for isolating 12 SU, 3 IMI, and 1 SA herbicides by using high-performance liquid chromatography/electrospray ionization-mass spectrometry (HPLC/ESI-MS) to identify and quantify these herbicides to 10 ng/l. This method was used to analyze 196 surface- and ground-water samples collected from May to August 1998 throughout the Midwestern United States, and more than 100 quality-assurance and quality-control samples. During the 16 weeks of the study, the HPLC/ESI-MS maintained excellent calibration linearity across the calibration range from 5 to 500 ng/l, with correlation coefficients of 0.9975 or greater. Continuing calibration verification standards at 100-ng/l concentration were analyzed throughout the study, and the average measured concentrations for individual herbicides ranged from 93 to 100 ng/l. Recovery of herbicides from 27 reagent-water samples spiked at 50 and 100 ng/l ranged from 39 to 92%, and averaged 73%. The standard deviation of recoveries ranged from 14 to 26%, and averaged 20%. This variability reflects multiple instruments, operators, and the use of automated and manual sample preparation. Spiked environmental water samples had similar recoveries, although for some herbicides, the sample matrix enhanced recoveries by as much as 200% greater than the spiked concentration. This matrix enhancement was sample- and compound-dependent. Concentrations of herbicides in unspiked duplicate environmental samples were typically within 25% of each other. The results demonstrate the usefulness of HPLC/ESI-MS for determining low-application-rate herbicides at ambient concentrations. Copyright (C) 2000 Elsevier Science B.V.

Workplace Measurements of Ultrafine Particles-A Literature Review.

PubMed

Viitanen, Anna-Kaisa; Uuksulainen, Sanni; Koivisto, Antti J; Hämeri, Kaarle; Kauppinen, Timo

2017-08-01

Workers are exposed to ultrafine particles (UFP) in a number of occupations. In order to summarize the current knowledge regarding occupational exposure to UFP (excluding engineered nanoparticles), we gathered information on UFP concentrations from published research articles. The aim of our study was to create a basis for future epidemiological studies that treat UFP as an exposure factor. The literature search found 72 publications regarding UFP measurements in work environments. These articles covered 314 measurement results and tabled concentrations. Mean concentrations were compared to typical urban UFP concentration level, which was considered non-occupational background concentration. Mean concentrations higher than the typical urban UFP concentration were reported in 240 workplace measurements. The results showed that workers' exposure to UFP may be significantly higher than their non-occupational exposure to background concentration alone. Mean concentrations of over 100 times the typical urban UFP concentration were reported in welding and metal industry. However, according to the results of the review, measurements of the UFP in work environments are, to date, too limited and reported too heterogeneous to allow us to draw general conclusions about workers' exposure. Harmonization of measurement strategies is essential if we are to generate more reliable and comparable data in the future. © The Author 2017. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Characterization of five typical agave plants used to produce mezcal through their simple lipid composition analysis by gas chromatography.

PubMed

Martínez-Aguilar, Juan Fco; Peña-Alvarez, Araceli

2009-03-11

Five agave plants typically used in Mexico for making mezcal in places included in the Denomination of Origin (Mexican federal law that establishes the territory within which mezcal can be produced) of this spirit were analyzed: Agave salmiana ssp. crassispina, A. salmiana var. salmiana, Agave angustifolia, Agave cupreata, and Agave karwinskii. Fatty acid and total simple lipid profiles of the mature heads of each plant were determined by means of a modified Bligh-Dyer extraction and gas chromatography. Sixteen fatty acids were identified, from capric to lignoceric, ranging from 0.40 to 459 microg/g of agave. Identified lipids include free fatty acids, beta-sitosterol, and groups of mono-, di-, and triacylglycerols, their total concentration ranging from 459 to 992 microg/g of agave. Multivariate analyses performed on the fatty acid profiles showed a close similarity between A. cupreata and A. angustifolia. This fact can be ascribed to the taxa themselves or differences in growing conditions, an issue that is still to be explored. These results help to characterize the agaves chemically and can serve to relate the composition of mezcals from various states of Mexico with the corresponding raw material.

Polychlorinated dioxins and furans from the World Trade Center attacks in exterior window films from lower Manhattan in New York City.

PubMed

Rayne, Sierra; Ikonomou, Michael G; Butt, Craig M; Diamond, Miriam L; Truong, Jennifer

2005-04-01

Samples of ambient organic films deposited on exterior window surfaces from lower Manhattan and Brooklyn in New York City were collected six weeks after the terrorist attacks at the World Trade Center (WTC) on September 11, 2001 and analyzed for polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). Total tetra- through octa-CDD/F concentrations in window films within 1 km of the WTC site in lower Manhattan ranged up to 630,000 pg/m2 (estimated as a mass concentration of ca. 1,300,000 pg/ g) and a maximum toxic equivalent (TEQ) concentration of 4700 TEQ/m2 (ca. 10 000 pg TEQ/g). Measurements at a background site 3.5 km away in Brooklyn showed lower concentrations at 130 pg TEQ/m2 (260 pg TEQ/g). Ambient gas-phase PCDD/F concentrations estimated for each site using an equilibrium partitioning model suggested concentrations ranging from ca. 2700 fg-TEQ/m3 near the WTC site to the more typical urban concentration of 20 fg-TEQ/m3 atthe Brooklyn site. Multivariate analyses of 2,3,7,8-substitued congeners and homologue group profiles suggested unique patterns in films near the WTC site compared to that observed at background sites in the study area and in other literature-derived combustion source profiles. Homologue profiles near the WTC site were dominated by tetra-, penta-, and Hexa-CDD/Fs, and 2,3,7,8-substituted profiles contained mostly octa- and hexachlorinated congeners. In comparison, profiles in Brooklyn and near mid-Manhattan exhibited congener and homologue patterns comprised mainly of hepta- and octa-CDDs, similar to that commonly reported in background air and soil.

In-vehicle carbon dioxide concentration in commuting cars in Bangkok, Thailand.

PubMed

Luangprasert, Maytat; Vasithamrong, Chainarin; Pongratananukul, Suphasit; Chantranuwathana, Sunhapos; Pumrin, Suree; De Silva, I P D

2017-05-01

It is known that in-vehicle carbon dioxide (CO 2 ) concentration tends to increase due to occupant exhalation when the HVAC (heating, ventilation, and air conditioning) air is in recirculation mode. Field experiments were conducted to measure CO 2 concentration during typical commute in Bangkok, Thailand. The measured concentrations agreed with the concentration predicted using first-order mass balance equation, in both recirculating and outside air modes. The long-term transient decay of the concentration when the vehicle was parked and the HVAC system was turned off was also studied. This decay was found to follow Fickian diffusion process. The paper also provides useful operational details of the automotive HVAC system and fresh air ventilation exchange between cabin interior and exterior. Drivers in tropical Asian countries typically use HVAC recirculation mode in their automobiles. This behavior leads to excessive buildup of cabin CO 2 concentration levels. The paper describes the CO 2 buildup in a typical commute in Bangkok, Thailand. Auto manufacturers can potentially take measures to alleviate such high concentration levels. The paper also discusses the diffusion of CO 2 through the vehicle envelope, an area that has never been investigated before.

In-situ measurements of light-absorbing impurities in snow of glacier on Mt. Yulong and implications for radiative forcing estimates.

PubMed

Niu, Hewen; Kang, Shichang; Shi, Xiaofei; Paudyal, Rukumesh; He, Yuanqing; Li, Gang; Wang, Shijin; Pu, Tao; Shi, Xiaoyi

2017-03-01

The Tibetan Plateau (TP) or the third polar cryosphere borders geographical hotspots for discharges of black carbon (BC). BC and dust play important roles in climate system and Earth's energy budget, particularly after they are deposited on snow and glacial surfaces. BC and dust are two kinds of main light-absorbing impurities (LAIs) in snow and glaciers. Estimating concentrations and distribution of LAIs in snow and glacier ice in the TP is of great interest because this region is a global hotspot in geophysical research. Various snow samples, including surface aged-snow, superimposed ice and snow meltwater samples were collected from a typical temperate glacier on Mt. Yulong in the snow melt season in 2015. The samples were determined for BC, Organic Carbon (OC) concentrations using an improved thermal/optical reflectance (DRI Model 2001) method and gravimetric method for dust concentrations. Results indicated that the LAIs concentrations were highly elevation-dependent in the study area. Higher contents and probably greater deposition at relative lower elevations (generally <5000masl) of the glacier was observed. Temporal difference of LAIs contents demonstrated that LAIs in snow of glacier gradually increased as snow melting progressed. Evaluations of the relative absorption of BC and dust displayed that the impact of dust on snow albedo and radiative forcing (RF) is substantially larger than BC, particularly when dust contents are higher. This was verified by the absorption factor, which was <1.0. In addition, we found the BC-induced albedo reduction to be in the range of 2% to nearly 10% during the snow melting season, and the mean snow albedo reduction was 4.63%, hence for BC contents ranging from 281 to 894ngg -1 in snow of a typical temperate glacier on Mt. Yulong, the associated instantaneous RF will be 76.38-146.96Wm -2 . Further research is needed to partition LAIs induced glacial melt, modeling researches in combination with long-term in-situ observations of LAIs in glaciers is also urgent needed in the future work. Copyright © 2017 Elsevier B.V. All rights reserved.

Polybrominated diphenyl ethers in e-waste: Level and transfer in a typical e-waste recycling site in Shanghai, Eastern China

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

Li, Yue; Duan, Yan-Ping, E-mail: duanyanping@tongji.edu.cn; Huang, Fan

Highlights: • PBDEs were detected in the majority of e-waste. • PBDEs were found in TVs made in China after 1990. • The levels of ΣPBDEs in e-waste made in Japan far exceed the threshold limit of RoHS. • The inappropriate recycling and disposal of e-waste is an important source of PBDEs. - Abstract: Very few data for polybrominated diphenyl ethers (PBDEs) were available in the electronic waste (e-waste) as one of the most PBDEs emission source. This study reported concentrations of PBDEs in e-waste including printer, rice cooker, computer monitor, TV, electric iron and water dispenser, as well asmore » dust from e-waste, e-waste dismantling workshop and surface soil from inside and outside of an e-waste recycling plant in Shanghai, Eastern China. The results showed that PBDEs were detected in the majority of e-waste, and the concentrations of ΣPBDEs ranged from not detected to 175 g/kg, with a mean value of 10.8 g/kg. PBDEs were found in TVs made in China after 1990. The mean concentrations of ΣPBDEs in e-waste made in Korea, Japan, Singapore and China were 1.84 g/kg, 20.5 g/kg, 0.91 g/kg, 4.48 g/kg, respectively. The levels of ΣPBDEs in e-waste made in Japan far exceed the threshold limit of RoHS (1.00 g/kg). BDE-209 dominated in e-waste, accounting for over 93%. The compositional patterns of PBDEs congeners resembled the profile of Saytex 102E, indicating the source of deca-BDE. Among the samples of dust and surface soil from a typical e-waste recycling site, the highest concentrations of Σ{sub 18}PBDEs and BDE-209 were found in dust in e-waste, ranging from 1960 to 340,710 ng/g and from 910 to 320,400 ng/g, which were 1–2 orders of magnitude higher than other samples. It suggested that PBDEs released from e-waste via dust, and then transferred to surrounding environment.« less

Pyrethroid sorption to Sacramento River suspended solids and bed sediments

PubMed Central

Fojut, Tessa L.; Young, Thomas M.

2011-01-01

Sorption of pyrethroid insecticides to solid materials will typically dominate the fate and transport of these hydrophobic compounds in aquatic environments. Batch reactor isotherm experiments were performed with bifenthrin and λ-cyhalothrin with suspended material and bed sediment collected from the Sacramento River, CA. These batch reactor experiments were performed with low spiking concentrations and a long equilibration time (28 d) to be more relevant to environmental conditions. Sorption to suspended material and bed sediment was compared to examine the role of differential sorption between these phases in the environmental transport of pyrethroids. The equilibrium sorption data were fit to the Freundlich isotherm model and fit with r2 > 0.87 for all experiments. Freundlich exponents ranged from 0.72 ± 0.19 to 1.07 ± 0.050, indicating sorption nonlinearity for some of the experimental conditions and linearity for others over the concentration range tested. The Freundlich capacity factors were larger for the suspended solids than for the bed sediments and the suspended material had a higher specific surface area and higher organic carbon content compared to the bed sediment. Calculated organic carbon-normalized distribution coefficients were larger than those previously reported in the literature by approximately an order of magnitude and ranged from 106.16 to 106.68 at an equilibrium aqueous concentration of 0.1 µg/L. Higher than expected sorption of pyrethroids to the tested materials may be explained by sorption to black carbon and/or mineral surfaces. PMID:21191877

Synthesis, characterization and biocompatibility of ``green'' synthesized silver nanoparticles using tea polyphenols

NASA Astrophysics Data System (ADS)

Moulton, Michael C.; Braydich-Stolle, Laura K.; NadagoudaPresent Address: Pegasus Technical Services, 46 E. Hollister Street, Cincinnati, 45219, Ohio, Usa., Mallikarjuna N.; Kunzelman, Samantha; Hussain, Saber M.; Varma, Rajender S.

2010-05-01

Since ancient times, people have taken advantage of the antimicrobial effects of colloidal silver particles. Aside from the medical prospects, silver nanoparticles are found in a wide range of commercially available consumer products ranging from cosmetics to household cleansers. Current synthetic methods for creating silver nanoparticles typically call for potentially hazardous chemicals, extreme heat, and produce environmentally dangerous byproducts. Therefore, it is essential that novel ``green'' synthesis of nanoparticles becomes a reality, and it is imperative to fully analyze the potential toxic effects of these nanoparticles. In this study, we have shown that by reducing silver nitrate in solutions of tea extract or epicatechin of varying concentrations, spherical silver nanoparticles were formed that had controllable size distributions depending on the concentration of tea extract or epicatechin in the samples. Our ultra-resolution microscopy demonstrated that the nanoparticles were in fact interacting with the keratinocytes. Furthermore, evaluation of mitochondrial function (MTS) to assess cell viability and membrane integrity (LDH) in human keratinocytes showed that the silver nanoparticles were nontoxic. These results demonstrated that these nanoparicles are potentially biocompatible and warrant further evaluation in other biological systems.

Biohydrogen production and wastewater treatment from organic wastewater by anaerobic fermentation with UASB

NASA Astrophysics Data System (ADS)

Wang, Lu; Li, Yong-feng; Wang, Yi-xuan; Yang, Chuan-ping

2010-11-01

In order to discuss the ability of H2-production and wastewater treatment, an up-flow anaerobic sludge bed (UASB) using a synthesized substrate with brown sugar wastewater was conducted to investigate the hydrogen yield, hydrogen producing rate, fermentation type of biohydrogen production, and the chemical oxygen demand (COD) removal rate, respectively. The results show that when the biomass of inoculants was 22.5 g SSṡL-1 and the influent concentration, hydraulic retention time (HRT) and initial pH were within the ranges of 4000˜6000 mg CODṡL-1, 8 h and 5-5.5, respectively, and the biohydrogen producing reactor could work effectively. The maximum hydrogen production rate is 5.98 Lṡd-1. Simultaneously, the concentration of ethanol and acetic acid is around 80% of the aqueous terminal production in the system, which presents the typical ethanol type fermentation. pH is at the range of 4˜4.5 during the whole performing process, however, the removal rate of COD is just about 20%. Therefore, it's still needs further research to successfully achieve the biohydrogen production and wastewater treatment, simultaneously.

Uranium content and leachable fraction of fluorspars

USGS Publications Warehouse

Landa, E.R.; Councell, T.B.

2000-01-01

Much attention in the radiological health community has recently focused on the management and regulation of naturally occurring radioactive materials. Although uranium-bearing minerals are present in a variety of fluorspar deposits, their potential consideration as naturally occurring radioactive materials has received only limited recognition. The uranium content of 28 samples of acid- and cryolite-grade (>97% CaF2) fluorspar from the National Defense Stockpile was found to range from 120 to 24,200 ??g kg-1, with a mean of 2,145 ??g kg-1. As a point of comparison, the average concentration of uranium in the upper crust of the earth is about 2,500 ??g kg-1. Leachability of this uranium was assessed by means of the Toxicity Characteristic Leaching Procedure (TCLP). The TCLP extractable fraction ranged from 1 to 98%, with a mean of 24% of the total uranium. The typically low concentrations of uranium seen in these materials probably reflects the removal of uranium-bearing mineral phases during the beneficiation of the crude fluorspar ore to achieve industrial specifications. Future NORM studies should examine crude fluorspar ores and flotation tailings.

Carbon nanotube-sensor-integrated microfluidic platform for real-time chemical concentration detection.

PubMed

Yang, Li; Li, Minglin; Qu, Yanli; Dong, Zaili; Li, Wen J

2009-09-01

This paper presents the development of a chemical sensor employing electronic-grade carbon nanotubes (EG-CNTs) as the active sensing element for sodium hypochlorite detection. The sensor, integrated in a PDMS-glass microfluidic chamber, was fabricated by bulk aligning of EG-CNTs between gold microelectrode pairs using dielectrophoretic technique. Upon exposure to sodium hypochlorite solution, the characteristics of the carbon nanotube chemical sensor were investigated at room temperature under constant current mode. The sensor exhibited responsivity, which fits a linear logarithmic dependence on concentration in the range of 1/32 to 8 ppm, a detection limit lower than 5 ppb, while saturating at 16 ppm. The typical response time of the sensor at room temperature is on the order of minutes and the recovery time is a few hours. In particular, the sensor showed an obvious sensitivity to the volume of detected solution. It was found that the activation power of the sensor was extremely low, i.e. in the range of nanowatts. These results indicate great potential of EG-CNT for advanced nanosensors with superior sensitivity, ultra-low power consumption, and less fabrication complexity.

Effects of Ti doping on the dielectric properties of HfO{sub 2} nanoparticles

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

Pokhriyal, S.; Biswas, S., E-mail: drsomnathbiswas@gmail.com

2016-05-06

We report the effects of Ti doping on the dielectric properties of HfO{sub 2} [Hf{sub 1-x}Ti{sub x}O{sub 2} (x = 0.2-0.8)] nanoparticles at room temperature. The Hf{sub 1-x}Ti{sub x}O{sub 2} nanoparticles were synthesized by a wet chemical process. The structural and morphological properties of the derived samples were analyzed with X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and high resolution transmission electron microscopy (HRTEM). Impedance analysis was performed in pelletized samples in the frequency range of 1 MHz to 1 GHz. The obtained results were analyzed in correlation with microstructure and doping concentration in the derived samples. The averagemore » size of the Hf{sub 1-x}Ti{sub x}O{sub 2} nanoparticles is typically in the range of 4-8 nm depending on the processing temperature. The Hf{sub 1−x}Ti{sub x}O{sub 2} nanoparticles show reduction in crystallinity with the increase in Ti doping. The dielectric constants of the derived samples decrease with the increase in frequency. The ac-conductivity in the samples increases with the increase in frequency irrespective of Ti concentration and shows significant drop with the increase in Ti concentration at all frequencies.« less

Assessment of the performance of a compact concentric spectrometer system for Atmospheric Differential Optical Absorption Spectroscopy

NASA Astrophysics Data System (ADS)

Whyte, C.; Leigh, R. J.; Lobb, D.; Williams, T.; Remedios, J. J.; Cutter, M.; Monks, P. S.

2009-08-01

A breadboard demonstrator of a novel UV/VIS grating spectrometer for atmospheric research has been developed based upon a concentric arrangement of a spherical meniscus lens, concave spherical mirror and curved diffraction grating suitable for a range of remote sensing applications from the ground or space. The spectrometer is compact and provides high optical efficiency and performance benefits over traditional instruments. The concentric design is capable of handling high relative apertures, owing to spherical aberration and coma being near zero at all surfaces. The design also provides correction for transverse chromatic aberration and distortion, in addition to correcting for the distortion called "smile", the curvature of the slit image formed at each wavelength. These properties render this design capable of superior spectral and spatial performance with size and weight budgets significantly lower than standard configurations. This form of spectrometer design offers the potential for an exceptionally compact instrument for differential optical absorption spectroscopy (DOAS) applications particularly from space (LEO, GEO orbits) and from HAPs or ground-based platforms. The breadboard demonstrator has been shown to offer high throughput and a stable Gaussian line shape with a spectral range from 300 to 450 nm at better than 0.5 nm resolution, suitable for a number of typical DOAS applications.

Factors Contributing to the Off-Target Transport of Pyrethroid Insecticides From Urban Surfaces

PubMed Central

Jorgenson, Brant C.; Wissel-Tyson, Christopher; Young, Thomas M.

2013-01-01

Pyrethroid insecticides used in an urban and suburban context have been found in urban creek sediments and associated with toxicity in aquatic bioassays. The objectives of this study were to evaluate the main factors contributing to the off-target transport of pyrethroid insecticides from surfaces typical of residential landscapes. Controlled rainfall simulations over concrete, bare soil, and turf plots treated individually with pyrethroid insecticides in a suspension concentrate, an emulsifiable concentrate, or a granule formulation were conducted at different rainfall intensities and different product set-time intervals. Pyrethroid mass washoff varied by several orders of magnitude between experimental treatments. Suspension concentrate product application to concrete yielded significantly greater washoff than any other treatment; granule product application to turf yielded the least washoff. Fractional losses at 10 L of runoff ranged from 25.9% to 0.011% of pyrethroid mass applied and 10 L nominal mass losses ranged from 3,970 to 0.18 μg. Mass washoff depended principally on formulation and surface type combination and to a lesser degree set-time interval and rainfall intensity. Treatment effects were analyzed by ANOVA on main factors of formulation, surface type, and set time. Factor effects were not purely additive; a significant interaction between formulation and surface type was noted. PMID:22784034

Sulfates as chromophores for multiwavelength photoacoustic imaging phantoms

NASA Astrophysics Data System (ADS)

Fonseca, Martina; An, Lu; Beard, Paul; Cox, Ben

2017-12-01

As multiwavelength photoacoustic imaging becomes increasingly widely used to obtain quantitative estimates, the need for validation studies conducted on well-characterized experimental phantoms becomes ever more pressing. One challenge that such studies face is the design of stable, well-characterized phantoms and absorbers with properties in a physiologically realistic range. This paper performs a full experimental characterization of aqueous solutions of copper and nickel sulfate, whose properties make them close to ideal as chromophores in multiwavelength photoacoustic imaging phantoms. Their absorption varies linearly with concentration, and they mix linearly. The concentrations needed to yield absorption values within the physiological range are below the saturation limit. The shape of their absorption spectra makes them useful analogs for oxy- and deoxyhemoglobin. They display long-term photostability (no indication of bleaching) as well as resistance to transient effects (no saturable absorption phenomena), and are therefore suitable for exposure to typical pulsed photoacoustic light sources, even when exposed to the high number of pulses required in scanning photoacoustic imaging systems. In addition, solutions with tissue-realistic, predictable, and stable scattering can be prepared by mixing sulfates and Intralipid, as long as an appropriate emulsifier is used. Finally, the Grüneisen parameter of the sulfates was found to be larger than that of water and increased linearly with concentration.

Mercury distribution and deposition in glacier snow over western China.

PubMed

Zhang, Qianggong; Huang, Jie; Wang, Feiyue; Mark, Loewen; Xu, Jianzhong; Armstrong, Debbie; Li, Chaoliu; Zhang, Yulan; Kang, Shichang

2012-05-15

Western China is home to the largest aggregate of glaciers outside the polar regions, yet little is known about how the glaciers in this area affect the transport and cycling of mercury (Hg) regionally and globally. From 2005 to 2010, extensive glacier snow sampling campaigns were carried out in 14 snowpits from 9 glaciers over western China, and the vertical distribution profiles of Hg were obtained. The Total Hg (THg) concentrations in the glacier snow ranged from <1 to 43.6 ng L(-1), and exhibited clear seasonal variations with lower values in summer than in winter. Spatially, higher THg concentrations were typically observed in glacier snows from the northern region where atmospheric particulate loading is comparably high. Glacier snowpit Hg was largely dependent on particulate matters and was associated with particulate Hg, which is less prone to postdepositional changes, thus providing a valuable record of atmospheric Hg deposition. Estimated atmospheric Hg depositional fluxes ranged from 0.74 to 7.89 μg m(-2) yr(-1), agreeing very well with the global natural values, but are one to two orders of magnitude lower than that of the neighboring East Asia. Elevated Hg concentrations were observed in refrozen ice layers in several snowpits subjected to intense melt, indicating that Hg can be potentially released to meltwater.

Communicating uncertainty in circulation aspects of climate change

NASA Astrophysics Data System (ADS)

Shepherd, Ted

2017-04-01

The usual way of representing uncertainty in climate change is to define a likelihood range of possible futures, conditioned on a particular pathway of greenhouse gas concentrations (RCPs). Typically these likelihood ranges are derived from multi-model ensembles. However, there is no obvious basis for treating such ensembles as probability distributions. Moreover, for aspects of climate related to atmospheric circulation, such an approach generally leads to large uncertainty and low confidence in projections. Yet this does not mean that the associated climate risks are small. We therefore need to develop suitable ways of communicating climate risk whilst acknowledging the uncertainties. This talk will outline an approach based on conditioning the purely thermodynamic aspects of climate change, concerning which there is comparatively high confidence, on circulation-related aspects, and treating the latter through non-probabilistic storylines.

Investigating hydrogen peroxide in rainwater of a typical midsized city in tropical Brazil using a novel application of a fluorometric method

NASA Astrophysics Data System (ADS)

Scaramboni, C.; Crispim, C. P.; Toledo, J. C.; Campos, M. L. A. M.

2018-03-01

This work investigates the effect of public policies related to vehicle emissions on the lower tropospheric concentrations of H2O2 in a typical midsized city in tropical Brazil. The concentrations of H2O2, SO42-, and NO3- in rainwater samples were determined from 2014 to 2017 in the municipality of Ribeirão Preto in São Paulo State. A fluorometric method, based on the formation of a highly fluorescent product (2‧,7‧-dichlorofluorescein, DCF), was adapted and optimized for the measurement of H2O2 in natural water samples including seawater. The method was highly specific, accurate and sensitive (LOD = 2 nmol L-1). Its main advantage compared to others, was that the fluorophore remained stable for at least 48 h, offering a longer time interval in which to perform the analysis and therefore facilitating fieldwork. Concentrations of H2O2 in rainwater ranged from 5.8 to 96 μmol L-1, with VWM of 28.6 ± 1.4 μmol L-1 (n = 77). Solar radiation appeared to have a greater impact on production than on consumption of H2O2. The annual VWM concentrations of H2O2 in rainwater were negatively correlated with sulfate (at pH < 5) and nitrate, suggesting that national policies designed to reduce vehicle emissions of SO2 and NOx resulted in increased atmospheric H2O2 concentrations, impacting the oxidative capacity of the lower troposphere. Biomass burning emissions and photochemical reactions were also found to be important factors affecting the concentration of H2O2 in the atmosphere. This work expands the current records available for the Southern Hemisphere, where there is a considerable paucity of information regarding temporal production and loss of atmospheric H2O2.

Development of a Field-Deployable Methane Carbon Isotope Analyzer

NASA Astrophysics Data System (ADS)

Dong, Feng; Baer, Douglas

2010-05-01

Methane is a potent greenhouse gas, whose atmospheric surface mixing ratio has almost doubled compared with preindustrial values. Methane can be produced by biogenic processes, thermogenic processes or biomass, with different isotopic signatures. As a key molecule involved in the radiative forcing in the atmosphere, methane is thus one of the most important molecules linking the biosphere and atmosphere. Therefore precise measurements of mixing ratios and isotopic compositions will help scientists to better understand methane sources and sinks. To date, high precision isotope measurements have been exclusively performed with conventional isotope ratio mass spectrometry, which involves intensive labor and is not readily field deployable. Optical studies using infrared laser spectroscopy have also been reported to measure the isotopic ratios. However, the precision of optical-based analyses, to date, is typically unsatisfactory without pre-concentration procedures. We present characterization of the performance of a portable Methane Carbon Isotope Analyzer (MCIA), based on cavity enhanced laser absorption spectroscopy technique, that provides in-situ measurements of the carbon isotope ratio (13C/12C or del_13C) and methane mixing ratio (CH4). The sample is introduced to the analyzer directly without any requirement for pretreatment or preconcentration. A typical precision of less than 1 per mill (< 0.1%) with a 10-ppm methane sample can be achieved in a measurement time of less than 100 seconds. The MCIA can report carbon isotope ratio and concentration measurements over a very wide range of methane concentrations. Results of laboratory tests and field measurements will be presented.

Solvent vapour monitoring in work space by solid phase micro extraction.

PubMed

Li, K; Santilli, A; Goldthorp, M; Whiticar, S; Lambert, P; Fingas, M

2001-05-07

Solid phase micro extraction (SPME) is a fast, solvent-less alternative to conventional charcoal tube sampling/carbon disulfide extraction for volatile organic compounds (VOC). In this work, SPME was compared to the active sampling technique in a typical lab atmosphere. Two different types of fibre coatings were evaluated for solvent vapour at ambient concentration. A general purpose 100 microm film polydimethylsiloxane (PDMS) fibre was found to be unsuitable for VOC work, despite the thick coating. The mixed-phase carboxen/PDMS fibre was found to be suitable. Sensitivity of the SPME was far greater than charcoal sorbent tube method. Calibration studies using typical solvent such as dichloromethane (DCM), benzene (B) and toluene (T) showed an optimal exposure time of 5 min, with a repeatability of less than 20% for a broad spectrum of organic vapour. Minimum detectable amount for DCM is in the range of 0.01 microg/l (0.003 ppmv). Variation among different fibres was generally within 30% at a vapour concentration of 1 microg DCM/l, which was more than adequate for field monitoring purpose. Adsorption characteristics and calibration procedures were studied. An actual application of SPME was carried out to measure background level of solvent vapour at a bench where DCM was used extensively. Agreement between the SPME and the charcoal sampling method was generally within a factor of two. No DCM concentration was found to be above the regulatory limit of 50 ppmv.

Elucidation and short-term forecasting of microcystin concentrations in Lake Suwa (Japan) by means of artificial neural networks and evolutionary algorithms.

PubMed

Chan, Wai Sum; Recknagel, Friedrich; Cao, Hongqing; Park, Ho-Dong

2007-05-01

Non-supervised artificial neural networks (ANN) and hybrid evolutionary algorithms (EA) were applied to analyse and model 12 years of limnological time-series data of the shallow hypertrophic Lake Suwa in Japan. The results have improved understanding of relationships between changing microcystin concentrations, Microcystis species abundances and annual rainfall intensity. The data analysis by non-supervised ANN revealed that total Microcystis abundance and extra-cellular microcystin concentrations in typical dry years are much higher than those in typical wet years. It also showed that high microcystin concentrations in dry years coincided with the dominance of the toxic Microcystis viridis whilst in typical wet years non-toxic Microcystis ichthyoblabe were dominant. Hybrid EA were used to discover rule sets to explain and forecast the occurrence of high microcystin concentrations in relation to water quality and climate conditions. The results facilitated early warning by 3-days-ahead forecasting of microcystin concentrations based on limnological and meteorological input data, achieving an r(2)=0.74 for testing.

Effect of Silver-Emitting Filler on Antimicrobial and Mechanical Properties of Soft Denture Lining Material

PubMed Central

Jabłońska-Stencel, Ewa; Pakieła, Wojciech; Mertas, Anna; Bobela, Elżbieta; Kasperski, Jacek; Chladek, Grzegorz

2018-01-01

Colonization of silicone-based soft lining materials by pathogenic yeast-type fungi is a common problem associated with the use of dentures. In this study, silver sodium hydrogen zirconium phosphate (SSHZP) was introduced into polydimethylsiloxane-based material as an antimicrobial filler at concentrations of 0.25, 0.5, 1, 2, 4, 6, 8, 10, 12, and 14% (w/w). The in vitro antimicrobial efficacy was investigated. Candida albicans was used as a characteristic representative of pathogenic oral microflora. Staphylococcus aureus and Escherichia coli were used as the typical Gram-positive and Gram-negative bacterial strains, respectively. The effect of filler addition on the Shore A hardness, tensile strength, tensile bond strength, sorption, and solubility was investigated. An increase in the filler concentration resulted in an increase in hardness, sorption, and solubility, and for the highest concentration, a decrease in bond strength. The favorable combination of antimicrobial efficacy with other properties was achieved at filler concentrations ranging from 2% to 10%. These composites exhibited mechanical properties similar to the material without the antimicrobial filler and enhanced in vitro antimicrobial efficiency. PMID:29470441

Contaminant profiles for surface water, sediment, flora and fauna associated with the mangrove fringe along middle and lower eastern Tampa Bay.

PubMed

Lewis, M A; Russell, M J

2015-06-15

Contaminant concentrations are reported for surface water, sediment, flora and fauna collected during 2010-2011 from the mangrove fringe along eastern Tampa Bay, Florida. Concentrations of trace metals, chlorinated pesticides, atrazine, total polycyclic aromatic hydrocarbons, and polychlorinated biphenyls were species-, chemical- and location-specific. Contaminants in sediments did not exceed proposed individual sediment quality guidelines. Most sediment quality assessment quotients were less than one indicating the likelihood of no inhibitory effect based on chemical measurements alone. Faunal species typically contained more contaminants than plant species; seagrass usually contained more chemicals than mangroves. Bioconcentration factors for marine angiosperms were usually less than 10 and ranged between 1 and 31. Mercury concentrations (ppm) in blue crabs and fish did not exceed the U.S. Environmental Protection Agency fish tissue criterion of 0.3 and the U.S. Food and Drug Administration action level of 1.0. In contrast, total mercury concentrations in faunal species often exceeded guideline values for wildlife consumers of aquatic biota. Published by Elsevier Ltd.

Mainbelt asteroids - Dual-polarization radar observations

NASA Technical Reports Server (NTRS)

Ostro, S. J.; Campbell, D. B.; Shapiro, I. I.

1985-01-01

Observations of 20 asteroids in the main belt between Mars and Jupiter provide information about the nature of these objects' surfaces at centimeter-to-kilometer scales. At least one asteroid (Pallas) is extremely smooth at centimeter-to-meter scales. Each asteroid appears much rougher than the moon at some scale between several meters and many kilometers. The range of asteroid radar albedos is very broad and implies substantial variations in porosity or metal concentration (or both). The highest albedo estimate, for the asteroid Psyche, is consistent with a surface having porosities typical of lunar soil and a composition nearly entirely metallic.

Finger printing of mixed contaminants from former manufactured gas plant (MGP) site soils: Implications to bioremediation.

PubMed

Thavamani, Palanisami; Megharaj, Mallavarapu; Krishnamurti, G S R; McFarland, Ross; Naidu, Ravi

2011-01-01

Contaminants in general do not occur as single chemicals but as mixtures at any contaminated site. Gasworks sites are the typical mixed contaminated sites. These sites are not only subjected to PAH contamination but also varying degrees of heavy metal contamination. Bioremediation in these sites is often hindered by the presence of heavy metals. The co-occurrence of PAHs with heavy metals has not been systematically investigated. Metals are reported to inhibit the general soil microbiological processes. The total concentration of soluble metal in the system includes both free metal ion and complexed forms. Within bioavailable fraction, the most toxic form is the free metal species, which was not addressed well so far in gas works site characterisation. This study underpins the science and importance of metal bioavailability and speciation based site characterisation in mixed contaminated sites. In this study a detailed elemental chemistry of the gas works site soils are discussed using different methods. The PAH contamination was contributed by both low and high molecular weight PAHs. The total PAHs concentration ranged from 335 to 8645 mg/kg. Among most toxic metals Pb was found in high concentration ranging from 88 to 671 mg/kg, Cd 8 to 112 mg/kg and Zn varied from 64 to 488 mg/kg. Thermodynamic chemical equilibrium model VMINTEQ (Ver 2.52) was used to calculate the free metal species in gas works site soils. The percentage free metal species showed a different trend compared to total metal concentrations, free Zn species ranged 18-86%, free Cd was 26-87% and Pb showed lowest free metal percentage (0-17%). The bioavailable metal species and its implications to bioremediation have also been discussed. Copyright © 2010 Elsevier Ltd. All rights reserved.

Exposure Characteristics of Nanoparticles as Process By-products for the Semiconductor Manufacturing Industry.

PubMed

Choi, Kwang-Min; Kim, Jin-Ho; Park, Ju-Hyun; Kim, Kwan-Sick; Bae, Gwi-Nam

2015-01-01

This study aims to elucidate the exposure properties of nanoparticles (NPs; <100 nm in diameter) in semiconductor manufacturing processes. The measurements of airborne NPs were mainly performed around process equipment during fabrication processes and during maintenance. The number concentrations of NPs were measured using a water-based condensation particle counter having a size range of 10-3,000 nm. The chemical composition, size, and shape of NPs were determined by scanning electron microscopy and transmission electron microscopy techniques equipped with energy dispersive spectroscopy. The resulting concentrations of NPs ranged from 0.00-11.47 particles/cm(3). The concentration of NPs measured during maintenance showed a tendency to increase, albeit incrementally, compared to that measured during normal conditions (under typical process conditions without maintenance). However, the increment was small. When comparing the mean number concentration and standard deviation (n ± σ) of NPs, the chemical mechanical polishing (CMP) process was the highest (3.45 ± 3.65 particles/cm(3)), and the dry etch (ETCH) process was the lowest (0.11 ± 0.22 particles/cm(3)). The major NPs observed were silica (SiO2) and titania (TiO2) particles, which were mainly spherical agglomerates ranging in size from 25-280 nm. Sampling of semiconductor processes in CMP, chemical vapor deposition, and ETCH reveled NPs were <100 nm in those areas. On the other hand, particle size exceeded 100 nm in diffusion, metallization, ion implantation, and wet cleaning/etching process. The results show that the SiO2 and TiO2 are the major NPs present in semiconductor cleanroom environments.

Determination of lipid oxidation products in vegetable oils and marine omega-3 supplements

PubMed Central

Halvorsen, Bente Lise; Blomhoff, Rune

2011-01-01

Background There is convincing evidence that replacing dietary saturated fats with polyunsaturated fats (PUFA) decreases risk of cardiovascular diseases. Therefore, PUFA rich foods such as vegetable oils, fatty fish, and marine omega-3 supplements are recommended. However, PUFA are easily oxidizable and there is concern about possible negative health effects from intake of oxidized lipids. Little is known about the degree of lipid oxidation in such products. Objective To assess the content of lipid oxidation products in a large selection of vegetable oils and marine omega-3 supplements available in Norway. Both fresh and heated vegetable oils were studied. Design A large selection of commercially available vegetable oils and marine omega-3 supplements was purchased from grocery stores, pharmacies, and health food stores in Norway. The content of lipid oxidation products were measured as peroxide value and alkenal concentration. Twelve different vegetable oils were heated for a temperature (225°C) and time (25 minutes) resembling conditions typically used during cooking. Results The peroxide values were in the range 1.04–10.38 meq/kg for omega-3 supplements and in the range 0.60–5.33 meq/kg for fresh vegetable oils. The concentration range of alkenals was 158.23–932.19 nmol/mL for omega-3 supplements and 33.24–119.04 nmol/mL for vegetable oils. After heating, a 2.9–11.2 fold increase in alkenal concentration was observed for vegetable oils. Conclusions The contents of hydroperoxides and alkenals in omega-3 supplements are higher than in vegetable oils. After heating vegetable oils, a large increase in alkenal concentration was observed. PMID:21691461

Observation of nighttime new particle formation over the French Landes forest.

PubMed

Kammer, J; Perraudin, E; Flaud, P-M; Lamaud, E; Bonnefond, J M; Villenave, E

2018-04-15

Improving the understanding of processes related to atmospheric particle sources is essential to better assess future climate. Especially, how biogenic volatile organic compounds (BVOCs) are involved in new particle formation (NPF) is still unclear, highlighting the need for field studies in sites that have not yet been explored. Weakly anthropised, mostly composed of maritime pines (known as strong monoterpene emitters), vast and under the influence of sea spray inputs, the Landes forest (located in the southwestern part of France) is a suitable ecosystem to explore these questions. The aim of the present work was to investigate for the first time NPF in the Landes forest, and to identify the conditions for NPF. During a field campaign conducted in July 2015, clear NPF was observed during nighttime, at a high frequency rate (37.5%), whereas only two daytime episodes were observed. Growth rates during NPF events were in the range 9.0-15.7nmh -1 , and nucleation rates (J 10 ) in the range 0.8-8 particles cm 3 s -1 , typically in the range of reported values from rural sites. Nocturnal NPF started at sunset, lagging the reductions of temperature and ozone concentration as well as the increase of relative humidity, atmospheric stability and monoterpene concentration. We established that NPF occurred during more stratified atmosphere episodes, reflecting that NPF is more influenced by local processes at the Landes forest site (Bilos). Concentration of the sum of monoterpenes, here mainly α- and β-pinene, was observed to be maximal during NPF episodes. On the contrary, ozone concentration was lower, which may indicate a larger consumption during nights where NPF episodes occur. Results strongly suggest the contribution of BVOC oxidation to nocturnal NPF, in both nucleation and the growth stages. Copyright © 2017 Elsevier B.V. All rights reserved.

Occurrence of brominated persistent organic pollutants (PBDD/DFs, PXDD/DFs, and PBDEs) in Baltic wild salmon ( Salmo salar ) and correlation with PCDD/DFs and PCBs.

PubMed

Zacs, Dzintars; Rjabova, Jekaterina; Bartkevics, Vadims

2013-08-20

The contamination profiles of polybrominated dibenzo-p-dioxins (PBDDs), dibenzofurans (PBDFs), diphenyl ethers (PBDEs), and mixed monobromo/chloro dibenzo-p-dioxins (PXDDs) and dibenzofurans (PXDFs) were determined in the tissue of Baltic wild salmon and compared with those of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and biphenyls (PCBs). Out of the analyzed PXDD/DFs, only the 3-B-2,7,8-triCDF was detected (in the concentration range of 0.039-0.075 pg g(-1) fresh weight (f.w.)). The toxic equivalents (TEQs) for analyzed PBDD/DFs (0.074-0.142 pg TEQ g(-1) f.w.) were found to contribute on average 2.1% to the total PCDD/DF-PBDD/DF-TEQ. The total concentrations of 27 PBDE congeners were in the range of 1.3-5.6 ng g(-1) f.w., with an average of 3.3 ng g(-1) f.w. The levels of PCDD/DFs and PCBs were found to be in the range of 4.53-14.6 pg WHO(2005)-PCDD/DF-PCB-TEQ g(-1) f.w., and concentrations of these compounds in most of the analyzed samples were above the maximum levels specified in Commission Regulation (EU) No. 1259/2011. Good correlation was observed between WHO(2005)-PCDD/DF-TEQ and WHO(2005)-PCB-TEQ (r(2) = 0.98), and these parameters were well correlated with the total sum of PBDE concentrations (r(2) = 0.91 and r(2) = 0.94, respectively). The results suggest that the consumption of Baltic wild salmon has no crucial impact on the average POP intake for typical Latvians.

Relationships for mercury and selenium in muscle and ova of gravid freshwater fish.

PubMed

Donald, David B

2016-10-01

At high concentrations, mercury (Hg) is toxic to vertebrates, causing neurological, behavioral, and teratological dysfunction. Selenium (Se) not only is an essential element but also has a high affinity for Hg, binding to organic methyl mercury at a molar ratio of Se/Hg of 1:1. Ratios of <1 increase risk of Hg toxicity. For gravid fish, low concentrations of Se in ova could increase potential for Hg toxicity, compromising embryonic development and fitness of fry. Mercury and selenium concentrations and ratios were investigated in the muscle and ovaries of six species from five families of fish to assess potential for risk to ecological fitness. Molar ratios of Se/Hg in muscle were typically >18 for lower trophic level species but ≤2 for piscivores. For all species combined, the concentrations of Hg in ova were significantly related to concentrations of Hg in muscle. Concentrations of Se in ova versus muscle showed a similar significant relationship that was independent of muscle Hg concentration. Mean ova molar Se/Hg ratios were high, ranging from 69 to 955 for the 6 species. However, a declining relationship between the ova Se/Hg molar ratio and the muscle concentration of Hg for all species combined suggests that development of ova and fry might be compromised for those piscivores with the highest muscle Hg concentrations because of Hg-related Se deficiency.

Migrating Myeloid Cells Sense Temporal Dynamics of Chemoattractant Concentrations.

PubMed

Petrie Aronin, Caren E; Zhao, Yun M; Yoon, Justine S; Morgan, Nicole Y; Prüstel, Thorsten; Germain, Ronald N; Meier-Schellersheim, Martin

2017-11-21

Chemoattractant-mediated recruitment of hematopoietic cells to sites of pathogen growth or tissue damage is critical to host defense and organ homeostasis. Chemotaxis is typically considered to rely on spatial sensing, with cells following concentration gradients as long as these are present. Utilizing a microfluidic approach, we found that stable gradients of intermediate chemokines (CCL19 and CXCL12) failed to promote persistent directional migration of dendritic cells or neutrophils. Instead, rising chemokine concentrations were needed, implying that temporal sensing mechanisms controlled prolonged responses to these ligands. This behavior was found to depend on G-coupled receptor kinase-mediated negative regulation of receptor signaling and contrasted with responses to an end agonist chemoattractant (C5a), for which a stable gradient led to persistent migration. These findings identify temporal sensing as a key requirement for long-range myeloid cell migration to intermediate chemokines and provide insights into the mechanisms controlling immune cell motility in complex tissue environments. Published by Elsevier Inc.

Diesel particulate emissions from used cooking oil biodiesel.

PubMed

Lapuerta, Magín; Rodríguez-Fernández, José; Agudelo, John R

2008-03-01

Two different biodiesel fuels, obtained from waste cooking oils with different previous uses, were tested in a DI diesel commercial engine either pure or in 30% and 70% v/v blends with a reference diesel fuel. Tests were performed under a set of engine operating conditions corresponding to typical road conditions. Although the engine efficiency was not significantly affected, an increase in fuel consumption with the biodiesel concentration was observed. This increase was proportional to the decrease in the heating value. The main objective of the work was to study the effect of biodiesel blends on particulate emissions, measured in terms of mass, optical effect (smoke opacity) and size distributions. A sharp decrease was observed in both smoke and particulate matter emissions as the biodiesel concentration was increased. The mean particle size was also reduced with the biodiesel concentration, but no significant increases were found in the range of the smallest particles. No important differences in emissions were found between the two tested biodiesel fuels.

The toxicity of selected gasoline components to glucose methanogenesis by aquifer microorganisms

USGS Publications Warehouse

Mormile, Melanie R.; Suflita, Joseph M.

1996-01-01

Six model hydrocarbons, representing various classes of chemicals found in gasoline, and methyl ethyl ketone, were assayed for their inhibitory effect on glucose methanogenesis in slurries prepared from aquifer sediments and ground water. Biogas (CH4and CO2) production was monitored with an automated pressure transducer system. Benzene, 1-methyl naphthalene, and methyltert-butyl ether (MTBE) were found to have no inhibitory influence on biogas production rates at concentrations up to 71·7 mg/L. Similarly, octane, cyclohexane, indan, and methyl ethyl ketone (MEK) were found to have only marginal negative effects on the rate of biogas production in aquifer slurries, at concentrations ranging from 51·7 to 72·1 mg/L. Thus, gasoline components had low apparent toxicities to microorganisms responsible for glucose methanogenesis in aquifier slurries. As the concentrations of the assayed hydrocarbons are about 100 times those typically reported after an aquifer has been contaminated with gasoline, it is unlikely that individual hydrocarbons will substantially impact anaerobic metabolic processes.

Radiological Impact of Tritium from Gaseous Effluent Releases at Cook Nuclear Power Plant

NASA Astrophysics Data System (ADS)

Young, Joshua Allan

The purpose of this study was to investigate the washout of tritiated water by snow and rain from gaseous effluent releases at Donald C. Cook Nuclear Power Plant. Primary concepts studied were determination of washout coefficients for rainfall and snowfall; correlations between rainfall and snow fall tritium concentrations with tritium concentrations in the spent fuel pool, reactor cooling systems, and tritium release rates; and calculations of received doses from the process of recapture. The dose calculations are under the assumption of a maximally exposed individual to get the most conservative estimate of the effect that washout of tritiated water has on individuals around the plant site. This study is in addition to previous work that has been conducted at Cook Nuclear Power Plant for several years. The calculated washout coefficients were typically within the range of 1x10-7s -1 to 1x10-5s-1. A strong correlation between tritium concentration within the spent fuel pool and the tritium release rates was determined.

An HS-MRM Assay for the Quantification of Host-cell Proteins in Protein Biopharmaceuticals by Liquid Chromatography Ion Mobility QTOF Mass Spectrometry.

PubMed

Doneanu, Catalin; Fang, Jing; Alelyunas, Yun; Yu, Ying Qing; Wrona, Mark; Chen, Weibin

2018-04-17

The analysis of low-level (1-100 ppm) protein impurities (e.g., host-cell proteins (HCPs)) in protein biotherapeutics is a challenging assay requiring high sensitivity and a wide dynamic range. Mass spectrometry-based quantification assays for proteins typically involve protein digestion followed by the selective reaction monitoring/multiple reaction monitoring (SRM/MRM) quantification of peptides using a low-resolution (Rs ~1,000) tandem quadrupole mass spectrometer. One of the limitations of this approach is the interference phenomenon observed when the peptide of interest has the "same" precursor and fragment mass (in terms of m/z values) as other co-eluting peptides present in the sample (within a 1-Da window). To avoid this phenomenon, we propose an alternative mass spectrometric approach, a high selectivity (HS) MRM assay that combines the ion mobility separation of peptide precursors with the high-resolution (Rs ~30,000) MS detection of peptide fragments. We explored the capabilities of this approach to quantify low-abundance peptide standards spiked in a monoclonal antibody (mAb) digest and demonstrated that it has the sensitivity and dynamic range (at least 3 orders of magnitude) typically achieved in HCP analysis. All six peptide standards were detected at concentrations as low as 0.1 nM (1 femtomole loaded on a 2.1-mm ID chromatographic column) in the presence of a high-abundance peptide background (2 µg of a mAb digest loaded on-column). When considering the MW of rabbit phosphorylase (97.2 kDa), from which the spiked peptides were derived, the LOQ of this assay is lower than 50 ppm. Relative standard deviations (RSD) of peak areas (n = 4 replicates) were less than 15% across the entire concentration range investigated (0.1-100 nM or 1-1,000 ppm) in this study.

Atmospheric Hydrogen (H2) Concentrations from the CSIRO GASLAB Flask Sampling Network (1992 - 2001)

DOE Data Explorer

Steele, L. P. [Commonwealth Scientific and Industrial Research Organization (CSIRO), Atmospheric Research, Aspendale, Victoria, Australia; Krummel, P. B. [Commonwealth Scientific and Industrial Research Organization (CSIRO), Atmospheric Research, Aspendale, Victoria, Australia; Langenfelds, R. L. [Commonwealth Scientific and Industrial Research Organization (CSIRO), Atmospheric Research, Aspendale, Victoria, Australia

2003-01-01

Air samples from nine sites were collected from the CSIRO GASLAB Flask Sampling Network for the purpose of monitoring the atmospheric hydrogen (H2) concentrations. The listed data were obtained from flask air samples returned to the CSIRO GASLAB for analysis. Typical sample storage times ranged from days to weeks for some sites (e.g., Cape Grim) to as much as one year for Macquarie Island and the Antarctic sites. Experiments carried out to test for any change in sample H22 mixing ratio during storage have shown no consistent and systematic drift in these flask types over test periods of several months to years (Cooper et al., 1999). An annual cycle of H2 is evident, reflecting the seasonal nature of some of the major sources and sinks (Novelli et al., 1999).

Multi-scale structures and functional properties of starches from Indica hybrid, Japonica and waxy rice.

PubMed

Wang, Shujun; Li, Peiyan; Yu, Jinglin; Guo, Peng; Wang, Shuo

2017-09-01

The structural and functional properties of starches from three rice grains differing in amylose content (19.9, 13.4 and 0.8% for Japonica, Indica hybrid and waxy rice, respectively) were investigated using a range of characterization methods Indica hybrid starch (IHS) had the highest proportion of intermediate (DP 13-24) and long branch chains (DP≥37) and the lowest proportion of short branch chains (DP 6-12), whereas the opposite results were observed for Japonica starch (JS). The results for waxy rice starch (WS) were between those of IHS and JS. Rice starches showed a typical A-type X-ray diffraction pattern with the relative crystallinity ranging from 33.4% for JS to 39.4% for WS. Significant differences were observed in lamellar distance and short-range molecular order characterized by IR ratio of absorbances at 1047/1022cm -1 and full width of half maximum (FWHM) of the band at 480cm -1 . WS showed a higher swelling power and a lower close packing concentration at temperatures from 60 to 90°C. The lower peak viscosity of WS was attributed to the formation of less rigid swollen granules at a concentrated regime. WS showed a higher in vitro digestibility compared with IHS and JS. Copyright © 2017 Elsevier B.V. All rights reserved.

An Unaccounted Fraction of Marine Biogenic CaCO3 Particles

PubMed Central

Heldal, Mikal; Norland, Svein; Erichsen, Egil S.; Thingstad, T. Frede; Bratbak, Gunnar

2012-01-01

Biogenic production and sedimentation of calcium carbonate in the ocean, referred to as the carbonate pump, has profound implications for the ocean carbon cycle, and relate both to global climate, ocean acidification and the geological past. In marine pelagic environments coccolithophores, foraminifera and pteropods have been considered the main calcifying organisms. Here, we document the presence of an abundant, previously unaccounted fraction of marine calcium carbonate particles in seawater, presumably formed by bacteria or in relation to extracellular polymeric substances. The particles occur in a variety of different morphologies, in a size range from <1 to >100 µm, and in a typical concentration of 104–105 particles L−1 (size range counted 1–100 µm). Quantitative estimates of annual averages suggests that the pure calcium particles we counted in the 1–100 µm size range account for 2–4 times more CaCO3 than the dominating coccolithophoride Emiliania huxleyi and for 21% of the total concentration of particulate calcium. Due to their high density, we hypothesize that the particles sediment rapidly, and therefore contribute significantly to the export of carbon and alkalinity from surface waters. The biological and environmental factors affecting the formation of these particles and possible impact of this process on global atmospheric CO2 remains to be investigated. PMID:23110119

Meteorological Contribution to Variability in Particulate Matter Concentrations

NASA Astrophysics Data System (ADS)

Woods, H. L.; Spak, S. N.; Holloway, T.

2006-12-01

Local concentrations of fine particulate matter (PM) are driven by a number of processes, including emissions of aerosols and gaseous precursors, atmospheric chemistry, and meteorology at local, regional, and global scales. We apply statistical downscaling methods, typically used for regional climate analysis, to estimate the contribution of regional scale meteorology to PM mass concentration variability at a range of sites in the Upper Midwestern U.S. Multiple years of daily PM10 and PM2.5 data, reported by the U.S. Environmental Protection Agency (EPA), are correlated with large-scale meteorology over the region from the National Centers for Environmental Prediction (NCEP) reanalysis data. We use two statistical downscaling methods (multiple linear regression, MLR, and analog) to identify which processes have the greatest impact on aerosol concentration variability. Empirical Orthogonal Functions of the NCEP meteorological data are correlated with PM timeseries at measurement sites. We examine which meteorological variables exert the greatest influence on PM variability, and which sites exhibit the greatest response to regional meteorology. To evaluate model performance, measurement data are withheld for limited periods, and compared with model results. Preliminary results suggest that regional meteorological processes account over 50% of aerosol concentration variability at study sites.

Characterization of aerosol composition, concentrations, and sources at Baengnyeong Island, Korea using an aerosol mass spectrometer

NASA Astrophysics Data System (ADS)

Lee, Taehyoung; Choi, Jinsoo; Lee, Gangwoong; Ahn, Junyoung; Park, Jin Soo; Atwood, Samuel A.; Schurman, Misha; Choi, Yongjoo; Chung, Yoomi; Collett, Jeffrey L.

2015-11-01

To improve understanding of the sources and chemical properties of particulate pollutants on the western side of the Korean Peninsula, an Aerodyne High Resolution Time of Flight Aerosol Mass Spectrometer (HR-ToF-AMS) measured non-refractory fine (PM1) particles from May to November, 2011 at Baengnyeong Island, South Korea. Organic matter and sulfate were generally the most abundant species and exhibited maximum concentrations of 36 μg/m3 and 39 μg/m3, respectively. Nitrate concentrations peaked at 32 μg/m3 but were typically much lower than sulfate and organic matter concentrations. May, September, October, and November featured the highest monthly average concentrations, with lower concentrations typically observed from June through August. Potential source contribution function (PSCF) analysis and individual case studies revealed that transport from eastern China, an area with high SO2 emissions, was associated with high particulate sulfate concentrations at the measurement site. Observed sulfate aerosol sometimes was fully neutralized by ammonium but often was acidic; the average ammonium to sulfate molar ratio was 1.49. Measured species size distributions revealed a range of sulfate particle size distributions with modes between 100 and 600 nm. Organic aerosol source regions were widespread, including contributions from eastern China and South Korea. Positive matrix factorization (PMF) analysis indicated three "factors," or types of organic aerosol, comprising one primary, hydrocarbon-like organic aerosol (HOA) and two oxidized organic aerosol (OOA) components, including a more oxidized (MO-OOA) and a less oxidized (LO-OOA) oxidized organic aerosol. On average, HOA and OOA contributed 21% and 79% of the organic mass (OM), respectively, with the MO-OOA fraction nearly three times as abundant as the LO-OOA fraction. Biomass burning contributions to observed OM were low during the late spring/early summer agricultural burning season in eastern China, since airflow into eastern China during the Asian Monsoon generally prevents transport of emissions eastward to the Korean Peninsula. Concentrations of the m/z 60 AMS biomass burning marker were more abundant in autumn, when transport patterns appeared to bring some smoke from fires in northern Asia to the island.

Estimating suspended sediment and trace element fluxes in large river basins: Methodological considerations as applied to the NASQAN programme

USGS Publications Warehouse

Horowitz, A.J.; Elrick, K.A.; Smith, J.J.

2001-01-01

In 1994, the NASQAN (National Stream Quality Accounting Network) programme was redesigned as a flux-based water-quality monitoring network for the Mississippi, Columbia, Colorado, and Rio Grande Basins. As the new programme represented a departure from the original, new sampling, processing, analytical, and data handling procedures had to be selected/developed to provide data on discharge, suspended sediment concentration, and the concentrations of suspended sediment and dissolved trace elements. Annual suspended sediment fluxes were estimated by summing daily instantaneous fluxes based on predicted suspended sediment concentrations derived from discharge-based log-log regression (rating-curve) models. The models were developed using both historical and current site-specific discharge and suspended sediment concentrations. Errors using this approach typically are less than ?? 10% for the 3-year reporting period; however, the magnitude of the errors increases substantially for temporal spans shorter than 1 year. Total, rather than total-recoverable, suspended sediment-associated trace element concentrations were determined by direct analysis of material dewatered from large-volume whole-water samples. Site-specific intra- and inter-annual suspended sediment-associated chemical variations were less (typically by no more than a factor of two) than those for either discharge or suspended sediment concentrations (usually more than 10-fold). The concentrations, hence the annual fluxes, for suspended sediment-associated phosphorus and organic carbon, determined by direct analyses, were higher than those determined using a more traditional paired, whole-water/filtered-water approach (by factors ranging from 1.5- to 10-fold). This may be important for such issues as eutrophication and coastal productivity. Filtered water-associated (dissolved) trace element concentrations were markedly lower than those determined during the historical NASQAN programme; many were below their respective detection limits. This resulted from the use of clean sampling, processing, and analytical protocols. Hence, the fluxes for filtered water-associated (dissolved) Ag, Pb, Co, V, Be, Sb, and Se, as well as the total (filtered water plus suspended sediment-associated) fluxes for these constituents, could not be estimated.

Saharan Dust Particle Size And Concentration Distribution In Central Ghana

NASA Astrophysics Data System (ADS)

Sunnu, A. K.

2010-12-01

A.K. Sunnu*, G. M. Afeti* and F. Resch+ *Department of Mechanical Engineering, Kwame Nkrumah University of Science and Technology (KNUST) Kumasi, Ghana. E-mail: albertsunnu@yahoo.com +Laboratoire Lepi, ISITV-Université du Sud Toulon-Var, 83162 La Valette cedex, France E-mail: resch@univ-tln.fr Keywords: Atmospheric aerosol; Saharan dust; Particle size distributions; Particle concentrations. Abstract The Saharan dust that is transported and deposited over many countries in the West African atmospheric environment (5°N), every year, during the months of November to March, known locally as the Harmattan season, have been studied over a 13-year period, between 1996 and 2009, using a location at Kumasi in central Ghana (6° 40'N, 1° 34'W) as the reference geographical point. The suspended Saharan dust particles were sampled by an optical particle counter, and the particle size distributions and concentrations were analysed. The counter gives the total dust loads as number of particles per unit volume of air. The optical particle counter used did not discriminate the smoke fractions (due to spontaneous bush fires during the dry season) from the Saharan dust. Within the particle size range measured (0.5 μm-25 μm.), the average inter-annual mean particle diameter, number and mass concentrations during the northern winter months of January and February were determined. The average daily number concentrations ranged from 15 particles/cm3 to 63 particles/cm3 with an average of 31 particles/cm3. The average daily mass concentrations ranged from 122 μg/m3 to 1344 μg/m3 with an average of 532 μg/m3. The measured particle concentrations outside the winter period were consistently less than 10 cm-3. The overall dust mean particle diameter, analyzed from the peak representative Harmattan periods over the 13-year period, ranged from 0.89 μm to 2.43 μm with an average of 1.5 μm ± 0.5. The particle size distributions exhibited the typical distribution pattern for atmospheric aerosols with a coarse mode diameter situated at about 3.5 μm. The experimental results reported in this study will be important in validating satellite based observations and simulation models of the African dust plume towards the Gulf of Guinea during winter.

Dust Plume Modeling at Fort Bliss: Full Training Scenario

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

Chapman, Elaine G.; Rishel, Jeremy P.; Rutz, Frederick C.

2006-09-26

The potential for air quality impacts from heavy mechanized vehicles operating in the training ranges and on the unpaved main supply routes at Fort Bliss is being investigated. The investigation uses the atmospheric modeling system DUSTRAN to simulate fugitive dust emission and dispersion from typical activities occurring on the installation. This report conveys the results of DUSTRAN simulations conducted using a “Full Training” scenario developed by Fort Bliss personnel. he Full Training scenario includes simultaneous off-road activities of two full Heavy Brigade Combat Teams (HCBTs) and one HCBT battalion on three training ranges. Simulations were conducted for the six-day period,more » April 25-30, 2005, using previously archived meteorological records. Simulation results are presented in the form of 24-hour average PM10 plots and peak 1-hour PM10 concentration plots, where the concentrations represent contributions resulting from the specified military vehicular activities, not total ambient PM10 concentrations. Results indicate that the highest PM10 contribution concentrations occurred on April 30 when winds were light and variable. Under such conditions, lofted particulates generated by vehicular movement stay in the area of generation and are not readily dispersed. The effect of training duration was investigated by comparing simulations with vehicular activity extending over a ten hour period (0700 to 1700 MST) with simulations where vehicular activity was compressed into a one hour period (0700 to 0800 MST). Compressing all vehicular activity into one hour led to higher peak one-hour and 24-hour average concentration contributions, often substantially higher.« less

Variability of dissolved organic carbon in precipitation during storms at the Shale Hills Critical Zone Observatory

USGS Publications Warehouse

Iavorivska , Lidiia; Boyer, Elizabeth W.; Grimm, Jeffrey W.; Miller, Matthew P.; DeWalle, David R.; Davis, Kenneth J.; Kaye, Margot W.

2017-01-01

Organic compounds are removed from the atmosphere and deposited to the earth's surface via precipitation. In this study, we quantified variations of dissolved organic carbon (DOC) in precipitation during storm events at the Shale Hills Critical Zone Observatory, a forested watershed in central Pennsylvania (USA). Precipitation samples were collected consecutively throughout the storm during 13 events, which spanned a range of seasons and synoptic meteorological conditions, including a hurricane. Further, we explored factors that affect the temporal variability by considering relationships of DOC in precipitation with atmospheric and storm characteristics. Concentrations and chemical composition of DOC changed considerably during storms, with the magnitude of change within individual events being comparable or higher than the range of variation in average event composition among events. While some previous studies observed that concentrations of other elements in precipitation typically decrease over the course of individual storm events, results of this study show that DOC concentrations in precipitation are highly variable. During most storm events concentrations decreased over time, possibly as a result of washing out of the below-cloud atmosphere. However, increasing concentrations that were observed in the later stages of some storm events highlight that DOC removal with precipitation is not merely a dilution response. Increases in DOC during events could result from advection of air masses, local emissions during breaks in precipitation, or chemical transformations in the atmosphere that enhance solubility of organic carbon compounds. This work advances understanding of processes occurring during storms that are relevant to studies of atmospheric chemistry, carbon cycling, and ecosystem responses.

Concentration variance decay during magma mixing: a volcanic chronometer

PubMed Central

Perugini, Diego; De Campos, Cristina P.; Petrelli, Maurizio; Dingwell, Donald B.

2015-01-01

The mixing of magmas is a common phenomenon in explosive eruptions. Concentration variance is a useful metric of this process and its decay (CVD) with time is an inevitable consequence during the progress of magma mixing. In order to calibrate this petrological/volcanological clock we have performed a time-series of high temperature experiments of magma mixing. The results of these experiments demonstrate that compositional variance decays exponentially with time. With this calibration the CVD rate (CVD-R) becomes a new geochronometer for the time lapse from initiation of mixing to eruption. The resultant novel technique is fully independent of the typically unknown advective history of mixing – a notorious uncertainty which plagues the application of many diffusional analyses of magmatic history. Using the calibrated CVD-R technique we have obtained mingling-to-eruption times for three explosive volcanic eruptions from Campi Flegrei (Italy) in the range of tens of minutes. These in turn imply ascent velocities of 5-8 meters per second. We anticipate the routine application of the CVD-R geochronometer to the eruptive products of active volcanoes in future in order to constrain typical “mixing to eruption” time lapses such that monitoring activities can be targeted at relevant timescales and signals during volcanic unrest. PMID:26387555

ARAS: an automated radioactivity aliquoting system for dispensing solutions containing positron-emitting radioisotopes

DOE PAGES

Dooraghi, Alex A.; Carroll, Lewis; Collins, Jeffrey; ...

2016-03-09

Automated protocols for measuring and dispensing solutions containing radioisotopes are essential not only for providing a safe environment for radiation workers but also to ensure accuracy of dispensed radioactivity and an efficient workflow. For this purpose, we have designed ARAS, an automated radioactivity aliquoting system for dispensing solutions containing positron-emitting radioisotopes with particular focus on fluorine-18 (18F). The key to the system is the combination of a radiation detector measuring radioactivity concentration, in line with a peristaltic pump dispensing known volumes. Results show the combined system demonstrates volume variation to be within 5 % for dispensing volumes of 20 μLmore » or greater. When considering volumes of 20 μL or greater, the delivered radioactivity is in agreement with the requested amount as measured independently with a dose calibrator to within 2 % on average. In conclusion, the integration of the detector and pump in an in-line system leads to a flexible and compact approach that can accurately dispense solutions containing radioactivity concentrations ranging from the high values typical of [18F]fluoride directly produced from a cyclotron (~0.1-1 mCi μL -1) to the low values typical of batches of [18F]fluoride-labeled radiotracers intended for preclinical mouse scans (~1-10 μCi μL -1).« less

The application of FLUENT in simulating outcomes from chlorine leakage accidents in a typical chemical factory.

PubMed

Li, Jianfeng; Zhang, Bin; Tang, Sichuang; Tong, Ruipeng

2016-05-01

For improvements in market competitiveness, old brand chemical enterprises did some expansion and reconstruction on the base of original equipment. Because it is the reconstruction on the basis of the existing production equipment, it is bound to raise problems of reutilization existing in pipelines and equipment. A simplified typical chemical factory was established referring the actual workshop layout. Further, trustable accident scenarios were conducted to reveal the diffusion process. In a larger leakage rate, the chlorine leak-affected area in the downwind became larger a bit, also in a relatively shorter time, lethal scope will become larger quickly, resulting in more threats to the lives and properties in the vicinity of the factories. Further, it is not possible that the heavier-than-air effect of the chlorine will inevitably result in a higher concentration for a lower surface than that of higher surface. Actually at a certain height, a relatively higher monitoring surface has a larger diffusion range and a larger concentration than a relatively lower surface. It can be inferred that within a certain height, chlorine diffusion rate closer to the ground would be slower due to existence of turbulence or the relative resistance on the ground. © The Author(s) 2014.

Monitoring of thiopurine metabolites in patients with inflammatory bowel disease-what is actually measured?

PubMed

Vikingsson, Svante; Carlsson, Björn; Almer, Sven H C; Peterson, Curt

2009-06-01

Azathioprine and 6-mercaptopurine are often used in the treatment of patients with inflammatory bowel disease (IBD). They are prodrugs and undergo a complex metabolism to active and inactive metabolites. Thiopurine treatment is monitored in many laboratories by measuring metabolite concentrations in erythrocytes (red blood cells). The metabolites of interest are not measured directly but as hydrolysis products, which can be produced from several metabolites. The aim of this study was to examine which metabolites are actually measured during routine monitoring. Samples from 18 patients treated with a thiopurine were analyzed by a typical routine high-performance liquid chromatography method for therapeutic drug monitoring and by a newly developed specific method measuring thioguanosine monophosphate (TGMP), thioguanosine diphosphate (TGDP), and thioguanosine triphosphate (TGTP), as well as methylthioinosine monophosphate (meTIMP), and the results were compared. 6-Thioguanine nucleotide (TGN) values detected by the routine method were 69% (range 40%-90%) of the sum of TGMP, TGDP, and TGTP measured by the specific method. TGTP and TGDP contributed 85% (range 78%-90%) and 14% (range 10%-21%) of the TGN total, respectively. Thioguanosine was not found in any patient sample. The concentration of meTIMP obtained by the routine method was 548% of the value obtained by the specific method (range 340%-718%). The difference in TGN measurements between the routine and specific methods can be explained by low hydrolysis efficiency in the routine method, although the most likely explanation for the difference in meTIMP values is that not yet identified metabolites are codetermined in the routine high-performance liquid chromatography method. Concentrations reported as TGN during therapeutic drug monitoring of thiopurine metabolites consist of TGDP and TGTP with a minor contribution of the TGMP. Concentrations reported as meTIMP or methyl mercaptopurine consist in part of meTIMP, but other not yet identified metabolites are codetermined.

Catchment chemostasis revisited: water quality responds differently to variations in weather and climate

NASA Astrophysics Data System (ADS)

Godsey, Sarah; Kirchner, James

2017-04-01

Solute concentrations in streamflow typically vary systematically with stream discharge, and the resulting concentration-discharge relationships are important signatures of catchment (bio)geochemical processes. Solutes derived from mineral weathering often exhibit decreasing concentrations with increasing flows, suggesting dilution of a kinetically limited weathering flux by a variable flux of water. However, Godsey et al. (2009) showed that concentration-discharge relationships of weathering-derived solutes in 59 headwater catchments were much flatter than this simple dilution model would predict. Instead, their analysis showed that these catchments behaved almost like chemostats, with rates of solute production and/or mobilization that were nearly proportional to water fluxes, on both event and inter-annual time scales. Here we re-examine these findings using data from roughly 1000 catchments, ranging from ˜10 to >1,000,000 km2 in drainage area, and spanning a wide range of lithologic and climatic settings. Concentration-discharge relationships among this much larger set of much larger catchments are broadly consistent with the chemostatic behavior described by Godsey et al. (2009). Among these same catchments, however, site-to-site variations in mean concentrations are strongly (negatively) correlated with long-term average precipitation and discharge, suggesting strong dilution of stream concentrations under long-term leaching of the critical zone. The picture that emerges is one in which, on event and inter-annual time scales, stream solute concentrations are chemostatically buffered by groundwater storage and fast chemical reactions (such as ion exchange), but on much longer time scales, the catchment's chemostatic "set point" is determined by climatically driven critical zone evolution. Examples illustrating the different influences of (short-term) weather and (long-term) climate on water quality will be presented, and their implications will be discussed. Godsey, S.E., J.W. Kirchner and D.W. Clow, Concentration-discharge relationships reflect chemostatic characteristics of US catchments, Hydrological Processes, 23, 1844-1864, 2009.

Methylmercury is the predominant form of mercury in bird eggs: a synthesis

USGS Publications Warehouse

Ackerman, Joshua T.; Herzog, Mark P.; Schwarzbach, Steven E.

2013-01-01

Bird eggs are commonly used in mercury monitoring programs to assess methylmercury contamination and toxicity to birds. However, only 6% of >200 studies investigating mercury in bird eggs have actually measured methylmercury concentrations in eggs. Instead, studies typically measure total mercury in eggs (both organic and inorganic forms of mercury), with the explicit assumption that total mercury concentrations in eggs are a reliable proxy for methylmercury concentrations in eggs. This assumption is rarely tested, but has important implications for assessing risk of mercury to birds. We conducted a detailed assessment of this assumption by (1) collecting original data to examine the relationship between total and methylmercury in eggs of two species, and (2) reviewing the published literature on mercury concentrations in bird eggs to examine whether the percentage of total mercury in the methylmercury form differed among species. Within American avocets (Recurvirostra americana) and Forster’s terns (Sterna forsteri), methylmercury concentrations were highly correlated (R2 = 0.99) with total mercury concentrations in individual eggs (range: 0.03–7.33 μg/g fww), and the regression slope (log scale) was not different from one (m = 0.992). The mean percentage of total mercury in the methylmercury form in eggs was 97% for American avocets (n = 30 eggs), 96% for Forster’s terns (n = 30 eggs), and 96% among all 22 species of birds (n = 30 estimates of species means). The percentage of total mercury in the methylmercury form ranged from 63% to 116% among individual eggs and 82% to 111% among species means, but this variation was not related to total mercury concentrations in eggs, foraging guild, nor to a species life history strategy as characterized along the precocial to altricial spectrum. Our results support the use of total mercury concentrations to estimate methylmercury concentrations in bird eggs.

Geochemical Indicators of Nitrogen flow in a Check-Dam Catchment in the Loess Plateau, China

NASA Astrophysics Data System (ADS)

Wang, Y.; Chen, S.; Huang, Y.; Gao, Y.

2017-12-01

The increasingly fragile ecological environment and associative nitrogen (N) biogeochemical cycle have become critical environmental and ecological issues in China's Loess Plateau. However, N flow and N source for typical catchments remains poorly understood in the Loess Plateau. In this study, we measured concentrations and isotopic signatures of N, hydrogen (H), and oxygen (O) in both rainfall and river water. Results showed that baseflow variation in total nitrogen (TN) concentrations ranged from 0.16 to 32.70 mg·L-1. Monthly TN deposition and monthly N wet deposition concentrations to river water were from 0.05 to 2.91 kg·hm-2 and from 0.28 to 11.26 kg, respectively, with significant variations between rainy and dry seasons. The range of variation in δ2H values for rainfall and baseflow were from -90.0‰ to +19.8‰ and from -67.2‰ to -38.4‰, respectively, while δ18O-H2O values ranged from -12.1‰ to +2.7‰ and from -9.3‰ to -3.6‰, respectively. Furthermore, NO3- δ15N and δ18O values in baseflow ranged from -2.0‰ to +20.5‰ and from +8.0‰ to +15.6‰, respectively. The results indicated that rainfall was affected by below-cloud secondary evaporation and caused strong isotopic kinetic fractionation to occur during the falling process. The NO3-in runoff mainly derived from the nitrification of soil organic matter (SOM), for which the proportion of manure or sewage was from 50.5% to 83%.

Secondhand smoke in cars: assessing children's potential exposure during typical journey conditions.

PubMed

Semple, Sean; Apsley, Andrew; Galea, Karen S; MacCalman, Laura; Friel, Brenda; Snelgrove, Vicki

2012-11-01

To measure levels of fine particulate matter in the rear passenger area of cars where smoking does and does not take place during typical real-life car journeys. Fine particulate matter (PM(2.5)) was used as a marker of secondhand smoke and was measured and logged every minute of each car journey undertaken by smoking and non-smoking study participants. The monitoring instrument was located at breathing zone height in the rear seating area of each car. Participants were asked to carry out their normal driving and smoking behaviours over a 3-day period. 17 subjects (14 smokers) completed a total of 104 journeys (63 smoking journeys). Journeys averaged 27 min (range 5-70 min). PM(2.5) levels averaged 85 and 7.4 μg/m(3) during smoking and non-smoking car journeys, respectively. During smoking journeys, peak PM(2.5) concentrations averaged 385 μg/m(3), with one journey measuring over 880 μg/m(3). PM(2.5) concentrations were strongly linked to rate of smoking (cigarettes per minute). Use of forced ventilation and opening of car windows were very common during smoking journeys, but PM(2.5) concentrations were still found to exceed WHO indoor air quality guidance (25 μg/m(3)) at some point in the measurement period during all smoking journeys. PM(2.5) concentrations in cars where smoking takes place are high and greatly exceed international indoor air quality guidance values. Children exposed to these levels of fine particulate are likely to suffer ill-health effects. There are increasing numbers of countries legislating against smoking in cars and such measures may be appropriate to prevent the exposure of children to these high levels of secondhand smoke.

Trace elements determination in seawater by ICP-MS with on-line pre-concentration on a Chelex-100 column using a ‘standard’ instrument setup.

PubMed Central

Søndergaard, Jens; Asmund, Gert; Larsen, Martin M.

2015-01-01

Trace element determination in seawater is analytically challenging due to the typically very low concentrations of the trace elements and the potential interference of the salt matrix. A common way to address the challenge is to pre-concentrate the trace elements on a chelating resin, then rinse the matrix elements from the resin and subsequently elute and detect the trace elements using inductively coupled plasma mass spectrometry (ICP-MS). This technique typically involves time-consuming pre-treatment of the samples for ‘off-line’ analyses or complicated sample introduction systems involving several pumps and valves for ‘on-line’ analyses. As an alternative, the following method offers a simple method for ‘on-line’ analyses of seawater by ICP-MS. As opposed to previous methods, excess seawater was pumped through the nebulizer of the ICP-MS during the pre-concentration step but the gas flow was adjusted so that the seawater was pumped out as waste without being sprayed into the instrument. Advantages of the method include: • Simple and convenient analyses of seawater requiring no changes to the ‘standard’ sample introduction system except from a resin-filled micro-column connected to the sample tube. The ‘standard’ sample introduction system refers to that used for routine digest-solution analyses of biota and sediment by ICP-MS using only one peristaltic pump; and • Accurate determination of the elements V, Mn, Co, Ni, Cu, Zn, Cd and Pb in a range of different seawater matrices verified by participation in 6 successive rounds of the international laboratory intercalibration program QUASIMEME. PMID:26258050

The pollution removal and stormwater reduction performance of street-side bioretention basins after ten years in operation.

PubMed

Lucke, Terry; Nichols, Peter W B

2015-12-01

This study evaluated the pollution removal and hydrologic performance of five, 10-year old street-side bioretention systems. The bioretention basins were subjected to a series of simulated rainfall events using synthetic stormwater. Four different pollution concentrations were tested on three of the bioretention basins. The four concentrations tested were: A) no pollution; B) typical Australian urban pollutant loads; C) double the typical pollution loads, and; D) five times the typical pollution loads. Tests were also undertaken to determine the levels of contaminant and heavy metals build-up that occurred in the filter media over the 10 year operational life of the bioretention systems. Although highly variable, the overall hydrological performance of the basins was found to be positive, with all basins attenuating flows, reducing both peak flow rates and total outflow volumes. Total suspended solids removal performance was variable for all tests and no correlation was found between performance and dosage. Total nitrogen (TN) removal was positive for Tests B, C and D. However, the TN removal results for Test A were found to be negative. Total phosphorus (TP) was the only pollutant to be effectively removed from all basins for all four synthetic stormwater tests. The study bioretention basins were found to export pollutants during tests where no pollutants were added to the simulated inflow water (Test A). Heavy metal and hydrocarbon testing undertaken on the bioretention systems found that the pollution levels of the filter media were still within acceptable limits after 10 years in operation. This field study has shown bioretention basin pollution removal performance to be highly variable and dependant on a range of factors including inflow pollution concentrations, filter media, construction methods and environmental factors. Further research is required in order to fully understand the potential stormwater management benefits of these systems. Copyright © 2015 Elsevier B.V. All rights reserved.

Occurrence and fate of benzotriazoles UV filters in a typical residential wastewater treatment plant in Harbin, China.

PubMed

Zhao, Xue; Zhang, Zi-Feng; Xu, Lei; Liu, Li-Yan; Song, Wei-Wei; Zhu, Fu-Jie; Li, Yi-Fan; Ma, Wan-Li

2017-08-01

Benzotriazoles (BTs) UV filters are widely used as ultraviolet absorbents for our daily products, which received increasing attention in the past decades. Residential wastewater treatment plant (WWTP) is both an important sink for wastewater and a key pollution source for receiving water for these chemicals. In this study, pretreatment and gas chromatography-tandem mass spectrometry analysis method were developed to determine the occurrence and fate of 9 BTs UV filters in wastewater and sludge from the WWTP with anaerobic-oxic treatment process (A/O) and biological aerated filter treatment process (BAF). Totally, 81 wastewater samples and 11 sludge samples were collected in four seasons. In wastewater, UV-326 and UV-329 were frequently detected, while the highest mean concentrations were detected for UV-234 and UV-329. The concentrations were in the range of 85% in A/O process and 60-77% in BAF process except for UV-350, which was more difficult to remove with lower removal efficiencies of 33.3% for both A/O and BAF. All the target chemicals except for UV-320 were detected in sludge samples with the mean concentration ranging from 0.90 ng/g to 303.39 ng/g. There was no significant difference with concentrations and removal efficiency among different seasons. Higher detection frequency and concentration of BTs UV filters in downstream of the receiving water system indicated the contribution of effluent of the WWTP. Compared with other rivers, the lower concentrations in surface water in the Songhua River indicated light pollution status with of BTs UV filters. Copyright © 2017 Elsevier Ltd. All rights reserved.

The self-absorption correction factors for 210Pb concentration in mining waste and influence on environmental radiation risk assessment.

PubMed

Bonczyk, Michal; Michalik, Boguslaw; Chmielewska, Izabela

2017-03-01

The radioactive lead isotope 210 Pb occurs in waste originating from metal smelting and refining industry, gas and oil extraction and sometimes from underground coal mines, which are deposited in natural environment very often. Radiation risk assessment requires accurate knowledge about the concentration of 210 Pb in such materials. Laboratory measurements seem to be the only reliable method applicable in environmental 210 Pb monitoring. One of the methods is gamma-ray spectrometry, which is a very fast and cost-effective method to determine 210 Pb concentration. On the other hand, the self-attenuation of gamma ray from 210 Pb (46.5 keV) in a sample is significant as it does not depend only on sample density but also on sample chemical composition (sample matrix). This phenomenon is responsible for the under-estimation of the 210 Pb activity concentration level often when gamma spectrometry is applied with no regard to relevant corrections. Finally, the corresponding radiation risk can be also improperly evaluated. Sixty samples of coal mining solid tailings (sediments created from underground mining water) were analysed. Slightly modified and adapted to the existing laboratory condition, a transmission method has been applied for the accurate measurement of 210 Pb concentration . The observed concentrations of 210 Pb range between 42.2 ÷ 11,700 Bq·kg -1 of dry mass. Experimentally obtained correction factors related to a sample density and elemental composition range between 1.11 and 6.97. Neglecting this factor can cause a significant error or underestimations in radiological risk assessment. The obtained results have been used for environmental radiation risk assessment performed by use of the ERICA tool assuming exposure conditions typical for the final destination of such kind of waste.

Major and trace element geochemistry and background concentrations for soils in Connecticut

USGS Publications Warehouse

Brown, Craig; Thomas, Margaret A.

2014-01-01

Soil samples were collected throughout Connecticut (CT) to determine the relationship of soil chemistry with the underlying geology and to better understand background concentrations of major and trace elements in soils. Soil samples were collected (1) from the upper 5 cm of surficial soil at 100 sites, (2) from the A horizon at 86 of these sites, and (3) from the deeper horizon, typically the C horizon, at 79 of these sites. The <2-millimeter fraction of each sample was analyzed for 44 elements by methods that yield the total or near-total elemental content. Sample sites were characterized by glacial setting, underlying bedrock geology, and soil type. These spatial data were used with element concentrations in the C-horizon to relate geologic factors to soil chemistry. Concentrations of elements in C-horizon soils varied with grain size in surficial glacial materials and with underlying rock types, as determined using nonparametric statistical procedures. Concentrations of most elements in C-horizon soils showed a positive correlation with silt and (or) clay content and were higher in surficial materials mapped as till, thick till, and (or) fines. Element concentrations in C-horizon soils showed significant differences among the underlying geologic provinces and were highest overlying the Grenville Belt and (or) the Grenville Shelf Sequence Provinces in western CT. These rocks consist mainly of carbonates and the relatively high element concentrations in overlying soils likely result from less influence of dilution by quartz compared to other provinces. Element concentrations in C-horizon soils in CT were compared with those in samples from other New England states overlying similar lithologic bedrock types. The upper range of As concentrations in C-horizon soils overlying the New Hampshire-Maine (NH-ME) Sequence in CT was 15 mg/kg, lower than the upper range of 24 mg/kg in C-horizon soils overlying the same sequence in ME. In CT, U concentration means were significantly higher in C-horizon soils overlying Avalonian granites, and U concentrations ranged as high as 14 mg/kg, compared to those in C-horizon soil samples collected from other New England states, which ranged as high as 6.1 mg/kg in a sample in NH overlying the NH-ME Sequence. Element concentrations in C-horizon soils in CT were compared with those in samples collected from shallower depths. Concentrations of most major elements were highest in C-horizon soil samples, including Al, Ca, Fe, K, Na, and Ti, but element concentrations showed a relatively similar pattern in A-horizon and surficial soil samples among the underlying geologic provinces. Trace element concentrations, including Ba, W, Ga, Ni, Cs, Rb, Sr, Th, Sc, and U, also were higher in C-horizon soil samples than in overlying soil samples. Concentrations of Mg, and several trace elements, including Mn, P, As, Nb, Sn, Be, Bi, Hg, Se, Sb, La, Co, Cr, Pb, V, Y, Cu, Pb, and Zn were highest in some A-horizon or surficial soils, and indicate possible contributions from anthropogenic sources. Because element concentrations in soils above the C horizon are more likely to be affected by anthropogenic factors, concentration ranges in C-horizon soils and their spatially varying geologic associations should be considered when estimating background concentrations of elements in CT soils.

Evaluation of Parameter Uncertainty Reduction in Groundwater Flow Modeling Using Multiple Environmental Tracers

NASA Astrophysics Data System (ADS)

Arnold, B. W.; Gardner, P.

2013-12-01

Calibration of groundwater flow models for the purpose of evaluating flow and aquifer heterogeneity typically uses observations of hydraulic head in wells and appropriate boundary conditions. Environmental tracers have a wide variety of decay rates and input signals in recharge, resulting in a potentially broad source of additional information to constrain flow rates and heterogeneity. A numerical study was conducted to evaluate the reduction in uncertainty during model calibration using observations of various environmental tracers and combinations of tracers. A synthetic data set was constructed by simulating steady groundwater flow and transient tracer transport in a high-resolution, 2-D aquifer with heterogeneous permeability and porosity using the PFLOTRAN software code. Data on pressure and tracer concentration were extracted at well locations and then used as observations for automated calibration of a flow and transport model using the pilot point method and the PEST code. Optimization runs were performed to estimate parameter values of permeability at 30 pilot points in the model domain for cases using 42 observations of: 1) pressure, 2) pressure and CFC11 concentrations, 3) pressure and Ar-39 concentrations, and 4) pressure, CFC11, Ar-39, tritium, and He-3 concentrations. Results show significantly lower uncertainty, as indicated by the 95% linear confidence intervals, in permeability values at the pilot points for cases including observations of environmental tracer concentrations. The average linear uncertainty range for permeability at the pilot points using pressure observations alone is 4.6 orders of magnitude, using pressure and CFC11 concentrations is 1.6 orders of magnitude, using pressure and Ar-39 concentrations is 0.9 order of magnitude, and using pressure, CFC11, Ar-39, tritium, and He-3 concentrations is 1.0 order of magnitude. Data on Ar-39 concentrations result in the greatest parameter uncertainty reduction because its half-life of 269 years is similar to the range of transport times (hundreds to thousands of years) in the heterogeneous synthetic aquifer domain. The slightly higher uncertainty range for the case using all of the environmental tracers simultaneously is probably due to structural errors in the model introduced by the pilot point regularization scheme. It is concluded that maximum information and uncertainty reduction for constraining a groundwater flow model is obtained using an environmental tracer whose half-life is well matched to the range of transport times through the groundwater flow system. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Towards microbial fermentation metabolites as markers for health benefits of prebiotics.

PubMed

Verbeke, Kristin A; Boobis, Alan R; Chiodini, Alessandro; Edwards, Christine A; Franck, Anne; Kleerebezem, Michiel; Nauta, Arjen; Raes, Jeroen; van Tol, Eric A F; Tuohy, Kieran M

2015-06-01

Available evidence on the bioactive, nutritional and putative detrimental properties of gut microbial metabolites has been evaluated to support a more integrated view of how prebiotics might affect host health throughout life. The present literature inventory targeted evidence for the physiological and nutritional effects of metabolites, for example, SCFA, the potential toxicity of other metabolites and attempted to determine normal concentration ranges. Furthermore, the biological relevance of more holistic approaches like faecal water toxicity assays and metabolomics and the limitations of faecal measurements were addressed. Existing literature indicates that protein fermentation metabolites (phenol, p-cresol, indole, ammonia), typically considered as potentially harmful, occur at concentration ranges in the colon such that no toxic effects are expected either locally or following systemic absorption. The endproducts of saccharolytic fermentation, SCFA, may have effects on colonic health, host physiology, immunity, lipid and protein metabolism and appetite control. However, measuring SCFA concentrations in faeces is insufficient to assess the dynamic processes of their nutrikinetics. Existing literature on the usefulness of faecal water toxicity measures as indicators of cancer risk seems limited. In conclusion, at present there is insufficient evidence to use changes in faecal bacterial metabolite concentrations as markers of prebiotic effectiveness. Integration of results from metabolomics and metagenomics holds promise for understanding the health implications of prebiotic microbiome modulation but adequate tools for data integration and interpretation are currently lacking. Similarly, studies measuring metabolite fluxes in different body compartments to provide a more accurate picture of their nutrikinetics are needed.

Investigation of pollution characteristics of polychlorinated biphenyls in the typical drinking water sources in Jiangsu Province, China.

PubMed

Hong, Ye; Chunhong, Zhou; Xiaoxiong, Zeng

2009-11-01

Concentration and composition of polychlorinated biphenyls (PCBs) in the typical drinking water sources in Jiangsu Province were studied by scene investigation and physical and chemical analyses as well. Total amount of PCBs in some surface water and surface microlayers exceeded the standard (20 ng/l) in the "Environmental Quality Standard of Surface Water". There were less PCBs in suspended substances and bottom mud. It reflected that there was less PCB pollution in drinking water sources in Jiangsu Province for quite a long period. The main kind of PCBs in the typical drinking water sources was dichlorobiphenyl. Monochlorobiphenyl and trichlorobiphenyl ranked next to dichlorobiphenyl. In the study of PCB distribution in drinking water sources, it was found that the concentration of PCBs in surface microlayer was higher than that in deep water. The concentration of PCBs along the Yangtze River bank was more than that in the middle of Yangtze River. PCBs in the typical drinking water sources mostly came from by-products in industrial production.

Monitoring of urea and potassium by reverse iontophoresis in vitro.

PubMed

Wascotte, Valentine; Delgado-Charro, M Begoña; Rozet, Eric; Wallemacq, Pierre; Hubert, Philippe; Guy, Richard H; Préat, Véronique

2007-06-01

Reverse iontophoresis is an alternative to blood sampling for the monitoring of endogenous molecules. Here, the potential of the technique to measure urea and potassium levels non-invasively, and to track their concentrations during hemodialysis, has been examined. In vitro experiments were performed to test (a) a series of subdermal urea and potassium concentrations typical of the pathophysiologic range, and (b) a decreasing profile of urea and potassium subdermal concentrations to mimic those which are observed during hemodialysis. (a) After 60-120 min of iontophoresis, linear relationships (p < 0.05) were established between both urea and potassium fluxes and their respective subdermal concentrations. The determination coefficients were above 0.9 after 1 h of current passage using sodium as an internal standard. (b) Reverse iontophoretic fluxes of urea and K(+) closely paralleled the decay of the respective concentrations in the subdermal compartment, as would occur during a hemodialysis session. These in vitro experiments demonstrate that urea and potassium can be quantitatively and proportionately extracted by reverse iontophoresis, even when the subdermal concentrations of the analytes are varying with time. These results suggest the non-invasive monitoring of urea and potassium to diagnose renal failure and during hemodialysis is feasible, and that in vivo measurements are warranted.

Multi-year levels and trends of non-methane hydrocarbon concentrations observed in ambient air in France

NASA Astrophysics Data System (ADS)

Waked, Antoine; Sauvage, Stéphane; Borbon, Agnès; Gauduin, Julie; Pallares, Cyril; Vagnot, Marie-Pierre; Léonardis, Thierry; Locoge, Nadine

2016-09-01

Measurements of 31 non-methane hydrocarbons (NMHCs) were carried out at three urban (Paris, 2003-2014, Strasbourg, 2002-2014 and Lyon, 2007-2014) sites in France over the period of a decade. A trend analysis was applied by means of the Mann-Kendall non-parametric test to annual and seasonal mean concentrations in order to point out changes in specific emission sources and to assess the impact of emission controls and reduction strategies. The trends were compared to those from three rural sites (Peyrusse-Vieille, 2002-2013, Tardière, 2003-2013 and Donon, 1997-2007). The results obtained showed a significant yearly decrease in pollutant concentrations over the study period and for the majority of species in the range of -1 to -7% in accordance with the decrease of NMHC emissions in France (-5 to -9%). Concentrations of long-lived species such as ethane and propane which are recognized as tracers of distant sources and natural gas remained constant. Compounds associated with combustion processes such as acetylene, propene, ethylene and benzene showed a significant decline in the range of -2% to -5% yr-1. These trends are consistent with those recently described at urban and background sites in the northern mid-latitudes and with emission inventories. C7-C9 aromatics such as toluene and xylenes as well as C4-C5 alkanes such as isopentane and isobutane also showed a significant decrease in the range of -3% to -7% yr-1. The decreasing trends in terms of % yr-1 observed at these French urban sites were typically higher for acetylene, ethylene and benzene than those reported for French rural sites of the national observatory of Measurement and Evaluation in Rural areas of trans-boundary Air pollution (MERA). The study also highlighted the difficult choice of a long term sampling site representative of the general trends of pollutant concentrations.

Water-quality and physical characteristics of streams in the Treyburn development area of Falls Lake watershed, North Carolina, 1994–98

USGS Publications Warehouse

Oblinger, C.J.; Cuffney, T.F.; Meador, M.R.; Garrett, R.G.

2002-01-01

Treyburn is a 5,400-acre planned, mixed-use development in the upper Neuse River Basin of North Carolina. The development, which began in 1986, is located in the Falls Lake watershed near three water-supply reservoirs-Lake Michie to the north, Falls Lake to the southeast, and Little River Reservoir to the west. A study began in 1988 to determine the water-quality characteristics of surface waters in and around the Treyburn development area.Data to characterize water quality at five different sites were collected from July 1994 through September 1998. Data from a previous study are available for some sites for the period 1988–93. The sites were selected to characterize water quality and quantity in and near the Treyburn development and included an undeveloped basin, a relatively small basin containing single-family residences and a golf course, a basin downstream from the western part of the development with some industrial land use, and two basins unaffected by the development where agricultural land is being converted to urban and forested land use.Suspended-sediment concentrations ranged from less than 1 to 581 milligrams per liter and were fairly uniform among the five sites. Median suspended-sediment concentrations ranged from 12 to 21 milligrams per liter. Few concentrations of metals and trace elements, except aluminum, iron, and manganese, exceeded the laboratory reporting levels or water-quality criteria. At one site, concentrations of silver exceeded both the action level and the reporting level; copper was detected at each site and exceeded the action level of 7 micrograms per liter at one site.The lowest range and median concentrations of total organic nitrogen, nitrate, ammonia, total phosphorus, and orthophosphorus occurred in the relatively undisturbed, forested site. The maximum concentration of organic nitrogen (1.97 milligrams per liter) occurred at one of the sites unaffected by the Treyburn development where agricultural land is being converted to urban land use. At all sites, ammonia concentrations ranged from less than 0.02 to 0.36 milligram per liter, and median concentrations were near the reporting level. Nitrate concentrations ranged from less than 0.05 to 0.80 milligram per liter.Phosphorus concentrations at all of the Treyburn study sites were low compared to phosphorus concentrations that typically exceed 0.1 milligram per liter at sites sampled nationally for the U.S. Geological Survey National Water-Quality Assessment Program, including the Albemarle-Pamlico study area in North Carolina. Total phosphorus concentrations ranged from less than 0.01 to 0.87 milligram per liter, and orthophosphorus concentrations ranged from less than 0.01 to 0.76 milligram per liter as phosphorus. The maximum concentrations of total phosphorus and orthophosphorus occurred at the Treyburn residential and golf-course site, likely as a result of the fertilizer applications associated with these two types of land use.Of the 119 different pesticides tested, 11 were detected in concentrations that exceeded the laboratory reporting levels, though in very low concentrations. Water samples from the residential and golf-course site contained the greatest number of pesticides (10). Five of six samples collected at this site had detectable concentrations of simazine, atrazine, and pendimethalin-all herbicides used to control weeds in crops or turf.Channel geometry was assessed at eight sites in the study area in February 1997. These sites were separated into three groups based on mean bank angle and mean channel width-to-depth ratios. Channel gradient ranged from 0.04 to 1.63 percent, and mean cross sectional area ranged from 31 to 1,227 square feet.Three macroinvertebrate samples were collected from each of 10 sites. These three samples were from areas designated as richest targeted habitats, depositional targeted habitats, and qualitative multitargeted habitats. Over 230 taxa were identified fromthese 10 sites. The North Carolina Biotic Indices ranged from 4.98 (excellent) to 6.82 (fair). River sites tended to have higher total taxa richness (91-108) than did the small, intermittent streams (49–84) or the midsize Mountain Creek (85). Intermittent streams represent fairly hostile environments for most aquatic organisms. Samples from richest targeted habitats typically were more than twice as rich as samples from depositional targeted habitats and represented from 50 to 75 percent of the taxa found at each site (mean of 62 percent). The industrial site lacked many of the mayfly taxa that were present at the undeveloped site. Mayflies are very sensitive to metals contamination, and their absence may indicate a possible problem. The supporting chemical information is not available for the industrial site, and additional study would be necessary to substantiate this possibility. The two sites with residential and golf-course land use tended to support more different types of sensitive invertebrates (that is, mayflies, stoneflies, and caddis flies) than did the forested/residential site, though the abundances of these taxa were very similar. Land-use effects were not evident based on a comparison among these sites.Indirect gradient analysis was used to determine patterns in the distribution of invertebrates and to examine the relations between these patterns and physical and chemical site characteristics determined in this study. This analysis supports the contention that the dominant factors accounting for the distribution of benthic invertebrates are associated with natural factors, such as basin size, rather than land use.Constituent loads at five study sites were calculated for nutrients, suspended sediment, and total organic carbon. The median annual total nitrogen yield ranged from 0.635 to 1.63 tons per square mile. The median annual phosphorus yield ranged from 0.046 to 0.619 ton per square mile, and the median annual orthophosphate yield ranged from 0.022 to 0.379 ton per square mile. Orthophosphate accounted for more than half of the phosphorus yield at the residential and golf-course site.The maximum suspended-sediment yield was 422 tons per square mile, and the minimum yield was 32 tons per square mile. The suspended-sediment yield at one of the sites unaffected by the Treyburn development where agricultural was being converted to urban land use was high compared to other forested basins in the Piedmont of North Carolina.Total organic carbon data sufficient for estimating loads were available at three of the five sites. Of these three sites, the undeveloped site had substantially more organic carbon yield than the other two sites.The only significant water-quality trend (alpha=0.05) was a downward trend for total nitrogen and organic nitrogen at the undeveloped site. The trend slope was small, only 0.019 milligram per liter as nitrogen or less than 9 percent of the median organic nitrogen concentration. No trend was observed for nitrite plus nitrate or for ammonia, indicating that the downward trend in total nitrogen was due only to organic nitrogen.

Infrasonic observations of large-scale HE events

NASA Technical Reports Server (NTRS)

Whitaker, Rodney W.; Mutschlecner, J. Paul; Davidson, Masha B.; Noel, Susan D.

1990-01-01

The Los Alamos Infrasound Program has been operating since about mid-1982, making routine measurements of low frequency atmospheric acoustic propagation. Generally, the authors work between 0.1 Hz to 10 Hz; however, much of the work is concerned with the narrower range of 0.5 to 5.0 Hz. Two permanent stations, St. George, UT, and Los Alamos, NM, have been operational since 1983, collecting data 24 hours a day. For the purposes of this discussion, the authors concentrate on their measurements of large, high explosive (HE) events at ranges of 250 km to 5330 km. Because their equipment is well suited for mobile deployments, they can easily establish temporary observing sites for special events. The measurements are from the permanent sites, as well as from various temporary sites. A few observations that are typical of the full data set are given.

Modeling and CFD simulation of nutrient distribution in picoliter bioreactors for bacterial growth studies on single-cell level.

PubMed

Westerwalbesloh, Christoph; Grünberger, Alexander; Stute, Birgit; Weber, Sophie; Wiechert, Wolfgang; Kohlheyer, Dietrich; von Lieres, Eric

2015-11-07

A microfluidic device for microbial single-cell cultivation of bacteria was modeled and simulated using COMSOL Multiphysics. The liquid velocity field and the mass transfer within the supply channels and cultivation chambers were calculated to gain insight in the distribution of supplied nutrients and metabolic products secreted by the cultivated bacteria. The goal was to identify potential substrate limitations or product accumulations within the cultivation device. The metabolic uptake and production rates, colony size, and growth medium composition were varied covering a wide range of operating conditions. Simulations with glucose as substrate did not show limitations within the typically used concentration range, but for alternative substrates limitations could not be ruled out. This lays the foundation for further studies and the optimization of existing picoliter bioreactor systems.

Mercury in soil, vegetable and human hair in a typical mining area in China: Implication for human exposure.

PubMed

Jia, Qin; Zhu, Xuemei; Hao, Yaqiong; Yang, Ziliang; Wang, Qi; Fu, Haihui; Yu, Hongjin

2018-06-01

Concentrations of total mercury (T-Hg) and methylmercury (MeHg) in soil, vegetables, and human hair were measured in a mercury mining area in central China. T-Hg and MeHg concentrations in soil ranged from 1.53 to 1054.97mg/kg and 0.88 to 46.52μg/kg, respectively. T-Hg concentrations was correlated with total organic carbon (TOC) content (R 2 =0.50, p<0.01) and pH values (R 2 =0.21, p<0.05). A significant linear relationship was observed between MeHg concentrations and the abundance of sulfate-reducing bacteria (SRB) (R 2 =0.39, p<0.05) in soil. Soil incubation experiments amended with specific microbial stimulants and inhibitors showed that Hg methylation was derived from SRB activity. T-Hg and MeHg concentrations in vegetables were 24.79-781.02μg/kg and 0.01-0.18μg/kg, respectively; levels in the edible parts were significantly higher than in the roots (T-Hg: p<0.05; MeHg: p<0.01). Hg species concentrations in rhizosphere soil were positively correlated to those in vegetables (p<0.01), indicating that soil was an important source of Hg in vegetables. Risk assessment indicated that the consumption of vegetables could result in higher probable daily intake (PDI) of T-Hg than the provisional tolerable daily intake (PTDI) for both adults and children. In contrast, the PDI of MeHg was lower than the reference dose. T-Hg and MeHg concentrations in hair samples ranged from 1.57 to 12.61mg/kg and 0.04 to 0.94mg/kg, respectively, and MeHg concentration in hair positively related to PDI of MeHg via vegetable consumption (R 2 =0.39, p<0.05), suggesting that vegetable may pose health risk to local residents. Copyright © 2017. Published by Elsevier B.V.

Mercury speciation and distribution in a glacierized mountain environment and their relevance to environmental risks in the inland Tibetan Plateau.

PubMed

Sun, Xuejun; Zhang, Qianggong; Kang, Shichang; Guo, Junming; Li, Xiaofei; Yu, Zhengliang; Zhang, Guoshuai; Qu, Dongmei; Huang, Jie; Cong, Zhiyuan; Wu, Guangjian

2018-08-01

Glacierized mountain environments can preserve and release mercury (Hg) and play an important role in regional Hg biogeochemical cycling. However, the behavior of Hg in glacierized mountain environments and its environmental risks remain poorly constrained. In this research, glacier meltwater, runoff and wetland water were sampled in Zhadang-Qugaqie basin (ZQB), a typical glacierized mountain environment in the inland Tibetan Plateau, to investigate Hg distribution and its relevance to environmental risks. The total mercury (THg) concentrations ranged from 0.82 to 6.98ng·L -1 , and non-parametric pairwise multiple comparisons of the THg concentrations among the three different water samples showed that the THg concentrations were comparable. The total methylmercury (TMeHg) concentrations ranged from 0.041 to 0.115ng·L -1 , and non-parametric pairwise multiple comparisons of the TMeHg concentrations showed a significant difference. Both the THg and MeHg concentrations of water samples from the ZQB were comparable to those of other remote areas, indicating that Hg concentrations in the ZQB watershed are equivalent to the global background level. Particulate Hg was the predominant form of Hg in all runoff samples, and was significantly correlated with the total suspended particle (TSP) and not correlated with the dissolved organic carbon (DOC) concentration. The distribution of mercury in the wetland water differed from that of the other water samples. THg exhibited a significant correlation with DOC as well as TMeHg, whereas neither THg nor TMeHg was associated with TSP. Based on the above findings and the results from previous work, we propose a conceptual model illustrating the four Hg distribution zones in glacierized environments. We highlight that wetlands may enhance the potential hazards of Hg released from melting glaciers, making them a vital zone for investigating the environmental effects of Hg in glacierized environments and beyond. Copyright © 2018 Elsevier B.V. All rights reserved.

Concentrations of polycyclic aromatic hydrocarbons: Their potential health risks and sources at three non-urban sites in Japan.

PubMed

Jadoon, Waqar A; Sakugawa, Hiroshi

2016-09-18

This investigation was undertaken to monitor particulate polycyclic aromatic hydrocarbons (PAHs) concentrations in order to determine their emission sources and potential human health risks in remote and rural areas of Japan. Seventeen PAHs in aerosol samples collected in remote (Kamihaya), coastal (Hiki) and inland (Higashi-Hiroshima) areas of Japan during 2013-2014 were analyzed using gas chromatography/mass spectrometry. Total PAH (Σ17PAH) concentrations in aerosol samples were in the range of 0.08-6.51 ng m(-3), 0.09-4.74 ng m(-3), and 0.21-6.53 ng m(-3) at Kamihaya, Hiki, and Higashi-Hiroshima sites, with mean concentrations of 1.63, 1.18, and 2.43 ng m(-3), respectively. Significant seasonal variation in concentrations occurred at Hiki and Higashi-Hiroshima, while no significant variation occurred at Kamihaya. Ambient air temperature greatly affected PAH concentrations in Higashi-Hiroshima, but had only moderate effects in Kamihaya and Hiki. Wind direction also influenced the concentrations of PAHs. Vehicle exhaust, industrial emissions, biomass combustion, and domestic heating and cooking were identified as the main PAH emission sources using principal component analysis. Backward trajectory calculations showed that domestically generated PAHs were significant in Kamihaya and Hiki, while in Higashi-Hiroshima concentrations were mainly influenced by long-range transport. The incremental lifetime lung cancer risk had values of 3.38 × 10(-5) and 1.84 × 10(-5) at Higashi-Hiroshima and Hiki, which are greater than the US EPA acceptable level (10(-6)). Typically, 5-6-ring PAHs contributed 95% to this overall health risk, of which benzo(a)pyrene was the largest contributor, followed by dibenz(a,h)anthracene at both residential sites. Clearly, stricter guidelines for PAHs need to be implemented at these sites to protect the population.

Total solar eclipse effects on VLF signals: Observations and modeling

NASA Astrophysics Data System (ADS)

Clilverd, Mark A.; Rodger, Craig J.; Thomson, Neil R.; Lichtenberger, János; Steinbach, Péter; Cannon, Paul; Angling, Matthew J.

During the total solar eclipse observed in Europe on August 11, 1999, measurements were made of the amplitude and phase of four VLF transmitters in the frequency range 16-24 kHz. Five receiver sites were set up, and significant variations in phase and amplitude are reported for 17 paths, more than any previously during an eclipse. Distances from transmitter to receiver ranged from 90 to 14,510 km, although the majority were <2000 km. Typically, positive amplitude changes were observed throughout the whole eclipse period on path lengths <2000 km, while negative amplitude changes were observed on paths >10,000 km. Negative phase changes were observed on most paths, independent of path length. Although there was significant variation from path to path, the typical changes observed were ~3 dB and ~50°. The changes observed were modeled using the Long Wave Propagation Capability waveguide code. Maximum eclipse effects occurred when the Wait inverse scale height parameter β was 0.5 km-1 and the effective ionospheric height parameter H' was 79 km, compared with β=0.43km-1 and H'=71km for normal daytime conditions. The resulting changes in modeled amplitude and phase show good agreement with the majority of the observations. The modeling undertaken provides an interpretation of why previous estimates of height change during eclipses have shown such a range of values. A D region gas-chemistry model was compared with electron concentration estimates inferred from the observations made during the solar eclipse. Quiet-day H' and β parameters were used to define the initial ionospheric profile. The gas-chemistry model was then driven only by eclipse-related solar radiation levels. The calculated electron concentration values at 77 km altitude throughout the period of the solar eclipse show good agreement with the values determined from observations at all times, which suggests that a linear variation in electron production rate with solar ionizing radiation is reasonable. At times of minimum electron concentration the chemical model predicts that the D region profile would be parameterized by the same β and H' as the LWPC model values, and rocket profiles, during totality and can be considered a validation of the chemical processes defined within the model.

Precise measurement of Fe isotopes in marine samples by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS).

PubMed

de Jong, Jeroen; Schoemann, Véronique; Tison, Jean-Louis; Becquevort, Sylvie; Masson, Florence; Lannuzel, Delphine; Petit, Jérôme; Chou, Lei; Weis, Dominique; Mattielli, Nadine

2007-04-18

A novel analytical technique for isotopic analysis of dissolved and particulate iron (Fe) from various marine environments is presented in this paper. It combines coprecipitation of dissolved Fe (DFe) samples with Mg(OH)(2), and acid digestion of particulate Fe (PFe) samples with double pass chromatographic separation. Isotopic data were obtained using a Nu Plasma MC-ICP-MS in dry plasma mode, applying a combination of standard-sample bracketing and external normalization by Cu doping. Argon interferences were determined prior to each analysis and automatically subtracted during analysis. Sample size can be varied between 200 and 600 ng of Fe per measurement and total procedural blanks are better than 10 ng of Fe. Typical external precision of replicate analyses (1S.D.) is +/-0.07 per thousand on delta(56)Fe and +/-0.09 per thousand on delta(57)Fe while typical internal precision of a measurement (1S.E.) is +/-0.03 per thousand on delta(56)Fe and +/-0.04 per thousand on delta(57)Fe. Accuracy and precision were assured by the analysis of reference material IRMM-014, an in-house pure Fe standard, an in-house rock standard, as well as by inter-laboratory comparison using a hematite standard from ETH (Zürich). The lowest amount of Fe (200 ng) at which a reliable isotopic measurement could still be performed corresponds to a DFe or PFe concentration of approximately 2 nmol L(-1) for a 2 L sample size. To show the versatility of the method, results are presented from contrasting environments characterized by a wide range of Fe concentrations as well as varying salt content: the Scheldt estuary, the North Sea, and Antarctic pack ice. The range of DFe and PFe concentrations encountered in this investigation falls between 2 and 2000 nmol L(-1) Fe. The distinct isotopic compositions detected in these environments cover the whole range reported in previous studies of natural Fe isotopic fractionation in the marine environment, i.e. delta(56)Fe varies between -3.5 per thousand and +1.5 per thousand. The largest fractionations were observed in environments characterized by redox changes and/or strong Fe cycling. This demonstrates the potential use of Fe isotopes as a tool to trace marine biogeochemical processes involving Fe.

Influence of plumes from biomass burning on atmospheric chemistry over the equatorial and tropical South Atlantic during CITE 3

NASA Technical Reports Server (NTRS)

Andreae, M. O.; Anderson, B. E.; Blake, D. R.; Bradshaw, J. D.; Collins, J. E.; Gregory, G. L.; Sachse, G. W.; Shipham, M. C.

1994-01-01

During all eight flights conducted over the equatorial and tropical South Atlantic in the course of the Chemical Instrumentation Test and Evaluation (CITE 3) experiment, we observed haze layers with elevated concentrations of aerosols, O3, CO, and other trace gases related to biomass burning emissions. They occurred at altitudes between 1000 and 5200 m and were usually only some 100-300 m thick. These layers extended horizontally over several 100 km and were marked by the presence of visible brownish haze. Air mass trajectories indicate that these layers originate in the biomass burning regions of Africa and South America and typically have aged at least 10 days since the time of emission. In the haze layers, O3 and CO concentrations up to 90 and 210 ppb were observed, respectively. The two species were highly correlated. The ratio concentrations in plume minus background concentrations of O3/CO is typically in the range 0.2-0.7, much higher than the ratios in the less aged plumes investigated previously in Amazonia. In most cases, aerosol (0.12-3 micrometer diameter) number concentrations were also elevated by up to 400/cu cm in the layers; aerosol enrichments were also strongly correlated with elevated CO levels. Clear correlations between CO and NO(x) enrichments were not apparent due to the age of the plumes, in which most NO(x) would have already reacted away within 1-2 days. Only in some of the plumes could clear correlations between NO(y) and CO be identified; the absence of a general correlation between NO(y) and CO may be due to instrumental limitations and to variable sinks for NO(y). The average enrichment of the ratio concentrations in plume minus background concentrations of NO(y)/CO was quite high, consistent with the efficient production of ozone observed in the plumes. The chemical characteristics of the haze layers, together with remote sensing information and trajectory calculations, suggest that fire emissions (in Africa and/or South America) are the primary source of the haze layer components.

Pyrethroid sorption to Sacramento River suspended solids and bed sediments.

PubMed

Fojut, Tessa L; Young, Thomas M

2011-04-01

Sorption of pyrethroid insecticides to solid materials will typically dominate the fate and transport of these hydrophobic compounds in aquatic environments. Batch reactor isotherm experiments were performed with bifenthrin and λ-cyhalothrin with suspended material and bed sediment collected from the Sacramento River, California, USA. These batch reactor experiments were performed with low spiking concentrations and a long equilibration time (28 d) to be more relevant to environmental conditions. Sorption to suspended material and bed sediment was compared to examine the role of differential sorption between these phases in the environmental transport of pyrethroids. The equilibrium sorption data were fit to the Freundlich isotherm model and fit with r(2)  > 0.87 for all experiments. Freundlich exponents ranged from 0.72 ± 0.19 to 1.07 ± 0.050, indicating sorption nonlinearity for some of the experimental conditions and linearity for others over the concentration range tested. The Freundlich capacity factors were larger for the suspended solids than for the bed sediments, and the suspended material had a higher specific surface area and higher organic carbon content compared to the bed sediment. Calculated organic carbon-normalized distribution coefficients were larger than those previously reported in the literature, by approximately an order of magnitude, and ranged from 10(6.16) to 10(6.68) at an equilibrium aqueous concentration of 0.1 µg/L. Higher than expected sorption of pyrethroids to the tested materials may be explained by sorption to black carbon and/or mineral surfaces. Copyright © 2011 SETAC.

The atmospheric lifetime of black carbon

NASA Astrophysics Data System (ADS)

Cape, J. N.; Coyle, M.; Dumitrean, P.

2012-11-01

Black carbon (BC) in the atmosphere contributes to the human health effects of particulate matter and contributes to radiative forcing of climate. The lifetime of BC, particularly the smaller particle sizes (PM2.5) which can be transported over long distances, is therefore an important factor in determining the range of such effects, and the spatial footprint of emission controls. Theory and models suggest that the typical lifetime of BC is around one week. The frequency distributions of measurements of a range of hydrocarbons at a remote rural site in southern Scotland (Auchencorth Moss) between 2007 and 2010 have been used to quantify the relationship between atmospheric lifetime and the geometric standard deviation of observed concentration. The analysis relies on an assumed common major emission source for hydrocarbons and BC, namely diesel-engined vehicles. The logarithm of the standard deviation of the log-transformed concentration data is linearly related to hydrocarbon lifetime, and the same statistic for BC can be used to assess the lifetime of BC relative to the hydrocarbons. Annual average data show BC lifetimes in the range 4-12 days, for an assumed OH concentration of 7 × 105 cm-3. At this site there is little difference in BC lifetime between winter and summer, despite a 3-fold difference in relative hydrocarbon lifetimes. This observation confirms the role of wet deposition as an important removal process for BC, as there is no difference in precipitation between winter and summer at this site. BC lifetime was significantly greater in 2010, which had 23% less rainfall than the preceding 3 years.

Determination of a wide range of volatile organic compounds in ambient air using multisorbent adsorption/thermal desorption and gas chromatography/mass spectrometry

USGS Publications Warehouse

Pankow, J.F.; Luo, W.; Isabelle, L.M.; Bender, D.A.; Baker, R.J.

1998-01-01

Adsorption/thermal desorption with multisorbent air-sampling cartridges was developed for the determination of 87 method analytes including halogenated alkanes, halogenated alkenes, ethers, alcohols, nitriles, esters, ketones, aromatics, a disulfide, and a furan. The volatilities of the compounds ranged from that of dichlorofluoromethane (CFC12) to that of 1,2,3- trichlorobenzene. The eight most volatile compounds were determined using a 1.5-L air sample and a sample cartridge containing 50 mg of Carbotrap B and 280 mg of Carboxen 1000; the remaining 79 compounds were determined using a 5-L air sample and a cartridge containing 180 mg of Carbotrap B and 70 mg of Carboxen 1000. Analysis and detection were by gas chromatography/mass spectrometry. The minimum detectable level (MDL) concentration values ranged from 0.01 parts per billion by volume (ppbv) for chlorobenzene to 0.4 ppbv for bromomethane; most of the MDL values were in the range 0.02-0.06 ppbv. No breakthrough was detected with the prescribed sample volumes. Analyte stability on the cartridges was very good. Excellent recoveries were obtained with independent check standards. Travel spike recoveries ranged from 90 to 110% for 72 of the 87 compounds. The recoveries were less than 70% for bromomethane and chloroethene and for a few compounds such as methyl acetate that are subject to losses by hydrolysis; the lowest travel spike recovery was obtained for bromomethane (62%). Blank values for all compounds were either below detection or very low. Ambient atmospheric sampling was conducted in New Jersey from April to December, 1997. Three sites characterized by low, moderate, and high densities of urbanization/traffic were sampled. The median detected concentrations of the compounds were either similar at all three sites (as with the chlorofluorocarbon compounds) or increased with the density of urbanization/traffic (as with dichloromethane, MTBE, benzene, and toluene). For toluene, the median detected concentrations were 0.23, 0.42, and 0.70 ppbv at the three sites. Analytical precision was measured using duplicate sampling. As expected, the precision deteriorated with decreasing concentration. At concentrations greater than 0.2 ppbv, most duplicates differed by less than 20%; below the MDL values, the differences between the duplicates were larger, but they were still typically less than 40%.

Dynamic MEMS devices for multi-axial fatigue and elastic modulus measurement

NASA Astrophysics Data System (ADS)

White, Carolyn D.; Xu, Rui; Sun, Xiaotian; Komvopoulos, Kyriakos

2003-01-01

For reliable MEMS device fabrication and operation, there is a continued demand for precise characterization of materials at the micron scale. This paper presents a novel material characterization device for fatigue lifetime testing. The fatigue specimen is subjected to multi-axial loading, which is typical of most MEMS devices. Polycrystalline silicon (polysilicon) fatigue devices were fabricated using the MUMPS process with a three layer mask process ground plane, anchor, and structural layer of polysilicon. A fatigue device consists of two or three beams, attached to a rotating ring and anchored to the substrate on each end. In order to generate a sufficiently large stress, the fatigue devices were tested in resonance to produce a von Mises equivalent stress as high as 1 GPa, which is in the fracture strength range reported for polysilicon. A further increase of the stress in the beam specimens was obtained by introducing a notch with a focused ion beam. The notch resulted into a stress concentration factor of about 3.8, thereby producing maximum von Mises equivalent stress in the range of 1 through 4 GPa. This study provides insight into multi-axial fatigue testing under typical MEMS conditions and additional information about micron-scale polysilicon mechanical behavior, which is the current basic building material for MEMS devices.

Comparison between agricultural and urban ground-water quality in the Mobile River Basin

USGS Publications Warehouse

Robinson, James L.

2003-01-01

The Black Warrior River aquifer is a major source of public water supply in the Mobile River Basin. The aquifer outcrop trends northwest - southeast across Mississippi and Alabama. A relatively thin shallow aquifer overlies and recharges the Black Warrior River aquifer in the flood plains and terraces of the Alabama, Coosa, Black Warrior, and Tallapoosa Rivers. Ground water in the shallow aquifer and the Black Warrior River aquifer is susceptible to contamination due to the effects of land use. Ground-water quality in the shallow aquifer and the shallow subcrop of the Black Warrior River aquifer, underlying an agricultural and an urban area, is described and compared. The agricultural and urban areas are located in central Alabama in Autauga, Elmore, Lowndes, Macon, Montgomery, and Tuscaloosa Counties. Row cropping in the Mobile River Basin is concentrated within the flood plains of major rivers and their tributaries, and has been practiced in some of the fields for nearly 100 years. Major crops are cotton, corn, and beans. Crop rotation and no-till planting are practiced, and a variety of crops are grown on about one-third of the farms. Row cropping is interspersed with pasture and forested areas. In 1997, the average farm size in the agricultural area ranged from 196 to 524 acres. The urban area is located in eastern Montgomery, Alabama, where residential and commercial development overlies the shallow aquifer and subcrop of the Black Warrior River aquifer. Development of the urban area began about 1965 and continued in some areas through 1995. The average home is built on a 1/8 - to 1/4 - acre lot. Ground-water samples were collected from 29 wells in the agricultural area, 30 wells in the urban area, and a reference well located in a predominately forested area. The median depth to the screens of the agricultural and urban wells was 22.5 and 29 feet, respectively. Ground-water samples were analyzed for physical properties, major ions, nutrients, and pesticides. Samples from 8 of the agricultural wells and all 30 urban wells were age dated using analyses of chlorofluorocarbon, sulfur hexafluoride, and dissolved gases. Ground water sampled from the agricultural wells ranged in age from about 14 to 34 years, with a median age of about 18.5 years. Ground water sampled from the urban wells ranged in age from about 1 to 45 years, with a median age of about 12 years. The ages estimated for the ground water are consistent with the geology and hydrology of the study area and the design of the wells. All of the agricultural and urban wells sampled for this study produce water from the shallow aquifer that overlies and recharges the Black Warrior River aquifer, or from the uppermost unit of the Black Warrior River aquifer. The wells are located in the same physiographic setting, have similar depths, and the water collected from the wells had a similar range in age. Statistically significant differences in ground-water quality beneath the agricultural and urban areas can reasonably be attributed to the effects of land use. Ground water from the agricultural wells typically had acidic pH values and low specific conductance and alkalinity values. The water contained few dissolved solids, and typically had small concentrations of ions. Some of the agricultural ground-water contained concentrations of ammonia, nitrite plus nitrate, phosphorus, orthophosphate, and dissolved organic carbon in concentrations that exceeded those typically found in ground water. Pesticides were detected in ground water collected from 25 of the 29 agricultural wells. Nineteen different pesticide compounds were detected a total of 83 times. Herbicides were the most frequently detected class of pesticides. The greatest concentration of any pesticide was an estimated value of 1.4 microgram per liter of fluometuron. The Wilcoxan rank sum test was used to determine statistically significant differences in water quality between the agricultural and urba

Pure-rotational spectrometry: a vintage analytical method applied to modern breath analysis.

PubMed

Hrubesh, Lawrence W; Droege, Michael W

2013-09-01

Pure-rotational spectrometry (PRS) is an established method, typically used to study structures and properties of polar gas-phase molecules, including isotopic and isomeric varieties. PRS has also been used as an analytical tool where it is particularly well suited for detecting or monitoring low-molecular-weight species that are found in exhaled breath. PRS is principally notable for its ultra-high spectral resolution which leads to exceptional specificity to identify molecular compounds in complex mixtures. Recent developments using carbon aerogel for pre-concentrating polar molecules from air samples have extended the sensitivity of PRS into the part-per-billion range. In this paper we describe the principles of PRS and show how it may be configured in several different modes for breath analysis. We discuss the pre-concentration concept and demonstrate its use with the PRS analyzer for alcohols and ammonia sampled directly from the breath.

On the refractive index of sodium iodide solutions for index matching in PIV

NASA Astrophysics Data System (ADS)

Bai, Kunlun; Katz, Joseph

2014-04-01

Refractive index matching has become a popular technique for facilitating applications of modern optical diagnostic techniques, such as particle image velocimetry, in complex systems. By matching the refractive index of solid boundaries with that of the liquid, unobstructed optical paths can be achieved for illumination and image acquisition. In this research note, we extend previously provided data for the refractive index of aqueous solutions of sodium iodide (NaI) for concentrations reaching the temperature-dependent solubility limit. Results are fitted onto a quadratic empirical expression relating the concentration to the refractive index. Temperature effects are also measured. The present range of indices, 1.333-1.51, covers that of typical transparent solids, from silicone elastomers to several recently introduced materials that could be manufactured using rapid prototyping. We also review briefly previous measurements of the refractive index, viscosity, and density of NaI solutions, as well as prior research that has utilized this fluid.

Physiologic Conditions Affect Toxicity of Ingested Industrial Fluoride

PubMed Central

Sauerheber, Richard

2013-01-01

The effects of calcium ion and broad pH ranges on free fluoride ion aqueous concentrations were measured directly and computed theoretically. Solubility calculations indicate that blood fluoride concentrations that occur in lethal poisonings would decrease calcium below prevailing levels. Acute lethal poisoning and also many of the chronic effects of fluoride involve alterations in the chemical activity of calcium by the fluoride ion. Natural calcium fluoride with low solubility and toxicity from ingestion is distinct from fully soluble toxic industrial fluorides. The toxicity of fluoride is determined by environmental conditions and the positive cations present. At a pH typical of gastric juice, fluoride is largely protonated as hydrofluoric acid HF. Industrial fluoride ingested from treated water enters saliva at levels too low to affect dental caries. Blood levels during lifelong consumption can harm heart, bone, brain, and even developing teeth enamel. The widespread policy known as water fluoridation is discussed in light of these findings. PMID:23840230

Physiologic conditions affect toxicity of ingested industrial fluoride.

PubMed

Sauerheber, Richard

2013-01-01

The effects of calcium ion and broad pH ranges on free fluoride ion aqueous concentrations were measured directly and computed theoretically. Solubility calculations indicate that blood fluoride concentrations that occur in lethal poisonings would decrease calcium below prevailing levels. Acute lethal poisoning and also many of the chronic effects of fluoride involve alterations in the chemical activity of calcium by the fluoride ion. Natural calcium fluoride with low solubility and toxicity from ingestion is distinct from fully soluble toxic industrial fluorides. The toxicity of fluoride is determined by environmental conditions and the positive cations present. At a pH typical of gastric juice, fluoride is largely protonated as hydrofluoric acid HF. Industrial fluoride ingested from treated water enters saliva at levels too low to affect dental caries. Blood levels during lifelong consumption can harm heart, bone, brain, and even developing teeth enamel. The widespread policy known as water fluoridation is discussed in light of these findings.

Dynamic interplay between uranyl phosphate precipitation, sorption, and phase evolution

DOE PAGES

Munasinghe, P. Sumudu; Elwood Madden, Megan E.; Brooks, Scott C.; ...

2015-04-17

We report that natural examples demonstrate uranyl-phosphate minerals can maintain extremely low levels of aqueous uranium in groundwaters due to their low solubility. Thus, greater understanding of the geochemical factors leading to uranyl phosphate precipitation may lead to successful application of phosphate-based remediation methods. However, the solubility of uranyl phosphate phases varies over >3 orders of magnitude, with the most soluble phases typically observed in lab experiments. To understand the role of common soil/sediment mineral surfaces in the nucleation and transformation of uranyl phosphate minerals under environmentally relevant conditions, we carried out batch experiments with goethite and mica at pHmore » 6 in mixed electrolyte solutions ranging from 1–800 μM U and 1–800 μM P. All experiments ended with uranium concentrations below the USEPA MCL for U, but with 2–3 orders of magnitude difference in uranium concentrations.« less

Matrix effects in applying mono- and polyclonal ELISA systems to the analysis of weathered oils in contaminated soil.

PubMed

Pollard, S J T; Farmer, J G; Knight, D M; Young, P J

2002-01-01

Commercial mono- and polyclonal enzyme-linked immunosorbent assay (ELISA) systems were applied to the on-site analysis of weathered hydrocarbon-contaminated soils at a former integrated steelworks. Comparisons were made between concentrations of solvent extractable matter (SEM) determined gravimetrically by Soxhlet (dichloromethane) extraction and those estimated immunologically by ELISA determination over a concentration range of 2000-330,000 mg SEM/kg soil dry weight. Both ELISA systems tinder-reported for the more weathered soil samples. Results suggest this is due to matrix effects in the sample rather than any inherent bias in the ELISA systems and it is concluded that, for weathered hydrocarbons typical of steelworks and coke production sites, the use of ELISA requires careful consideration as a field technique. Consideration of the target analyte relative to the composition of the hydrocarbon waste encountered appears critical.

Fracturing boosts output in California fields

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

Not Available

1979-12-01

The Diatomite has been a known oil-bearing zone in Kern County, California's S. Belridge and Lost Hills fields for many years, but only recently has the formation been exploitable. Fracturing proved to be the key to unlocking the diatomite's oil, resulting in a 6- to 8-fold increase in production. The Diatomite formation, at depths from 700 to 2000 ft, is characterized by porosity, low permeability, and saturations in the range of 40% oil, 50% water, and 10% gas. Early attempts to stimulate production in the Diatomite with fracturing failed. Later, studies of cores indicated the need for proppant concentrations ofmore » 2 to 3 psf of fracture area, providing fracture flow capacities of 2500 to 3000 md/ft. Halliburton's Versagel 1500 was selected as the ideal transport fluid capable of carrying 20-40 sand as the proppant at concentrations up to 12 lb/gal. A typical Diatomite fracturing job is described.« less

Large scale synthesis of nanostructured zirconia-based compounds from freeze-dried precursors

NASA Astrophysics Data System (ADS)

Gómez, A.; Villanueva, R.; Vie, D.; Murcia-Mascaros, S.; Martínez, E.; Beltrán, A.; Sapiña, F.; Vicent, M.; Sánchez, E.

2013-01-01

Nanocrystalline zirconia powders have been obtained at the multigram scale by thermal decomposition of precursors resulting from the freeze-drying of aqueous acetic solutions. This technique has equally made possible to synthesize a variety of nanostructured yttria or scandia doped zirconia compositions. SEM images, as well as the analysis of the XRD patterns, show the nanoparticulated character of those solids obtained at low temperature, with typical particle size in the 10-15 nm range when prepared at 673 K. The presence of the monoclinic, the tetragonal or both phases depends on the temperature of the thermal treatment, the doping concentration and the nature of the dopant. In addition, Rietveld refinement of the XRD profiles of selected samples allows detecting the coexistence of the tetragonal and the cubic phases for high doping concentration and high thermal treatment temperatures. Raman experiments suggest the presence of both phases also at relatively low treatment temperatures.

Enrichment of Extracellular Carbonic Anhydrase in the Sea Surface Microlayer and Its Effect on Air-Sea CO2 Exchange

NASA Astrophysics Data System (ADS)

Mustaffa, N. I. H.; Striebel, M.; Wurl, O.

2017-12-01

This paper describes the quantification of extracellular carbonic anhydrase (eCA) concentrations in the sea surface microlayer (SML), the boundary layer between the ocean and the atmosphere of the Indo-West Pacific. We demonstrated that the SML is enriched with eCA by 1.5 ± 0.7 compared to the mixed underlying water. Enrichment remains up to a wind speed of 7 m s-1 (i.e., under typical oceanic conditions). As eCA catalyzes the interconversion of HCO3- and CO2, it has been hypothesized that its enrichment in the SML enhances the air-sea CO2 exchange. We detected concentrations in the range of 0.12 to 0.76 nM, which can enhance the exchange by up to 15% based on the model approach described in the literature.

Toxic exposure in America: estimating fetal and infant health outcomes from 14 years of TRI reporting.

PubMed

Agarwal, Nikhil; Banternghansa, Chanont; Bui, Linda T M

2010-07-01

We examine the effect of exposure to a set of toxic pollutants that are tracked by the Toxic Release Inventory (TRI) from manufacturing facilities on county-level infant and fetal mortality rates in the United States between 1989 and 2002. Unlike previous studies, we control for toxic pollution from both mobile sources and non-TRI reporting facilities. We find significant adverse effects of toxic air pollution concentrations on infant mortality rates. Within toxic air pollutants we find that releases of carcinogens are particularly problematic for infant health outcomes. We estimate that the average county-level decreases in various categories of TRI concentrations saved in excess of 13,800 infant lives from 1989 to 2002. Using the low end of the range for the value of a statistical life that is typically used by the EPA of $1.8M, the savings in lives would be valued at approximately $25B.

Examination of the influence of environmental factors on contaminant vapor concentration attenuation factors using the U.S. EPA's vapor intrusion database.

PubMed

Yao, Yijun; Shen, Rui; Pennell, Kelly G; Suuberg, Eric M

2013-01-15

Those charged with the responsibility of estimating the risk posed by vapor intrusion (VI) processes have often looked to information contained in the U.S. Environmental Protection Agency (EPA)'s VI database for insight. Indoor air concentration attenuation factors have always been a key focus of this database, but the roles of different environmental factors in these attenuation processes are still unclear. This study aims to examine the influences of these factors in the context of the information in the VI database. The database shows that the attenuation factors vary over many orders of magnitude and that no simple statistical fluctuation around any typical mean value exists. Thus far, no simple explanation of this phenomenon has been presented. This paper examines various possible contributing factors to the enormous range of observed values, looking at which ones can plausibly contribute to explaining them.

Pressurized liquid extraction using water/isopropanol coupled with solid-phase extraction cleanup for industrial and anthropogenic waste-indicator compounds in sediment

USGS Publications Warehouse

Burkhardt, M.R.; ReVello, R.C.; Smith, S.G.; Zaugg, S.D.

2005-01-01

A broad range of organic compounds is recognized as environmentally relevant for their potential adverse effects on human and ecosystem health. This method was developed to better determine the distribution of 61 compounds that are typically associated with industrial and household waste as well as some that are toxic and known (or suspected) for endocrine-disrupting potential extracted from environmental sediment samples. Pressurized liquid extraction (PLE) coupled with solid-phase extraction (SPE) was used to reduce sample preparation time, reduce solvent consumption to one-fifth of that required using dichloromethane-based Soxhlet extraction, and to minimize background interferences for full scan GC/MS analysis. Recoveries from spiked Ottawa sand, commercially available topsoil, and environmental stream sediment, fortified at 4-720 ??g per compound, averaged 76 ?? 13%. Initial method detection limits for single-component compounds ranged from 12.5 to 520 ??g/kg, based on 25 g samples. Results from 103 environmental sediment samples show that 36 out of 61 compounds (59%) were detected in at least one sample with concentrations ranging from 20 to 100,000 ??g/kg. The most frequently detected compound, beta-sitosterol, a plant sterol, was detected in 87 of the 103 (84.5%) environmental samples with a concentration range 360-100,000 ??g/kg. Results for a standard reference material using dichloromethane Soxhlet-based extraction are also compared. ?? 2004 Published by Elsevier B.V.

Lab-Scale Study of the Calcium Carbonate Dissolution and Deposition by Marine Cyanobacterium Phormidium subcapitatum

NASA Technical Reports Server (NTRS)

Karakis, S. G.; Dragoeva, E. G.; Lavrenyuk, T. I.; Rogochiy, A.; Gerasimenko, L. M.; McKay, D. S.; Brown, I. I.

2006-01-01

Suggestions that calcification in marine organisms changes in response to global variations in seawater chemistry continue to be advanced (Wilkinson, 1979; Degens et al. 1985; Kazmierczak et al. 1986; R. Riding 1992). However, the effect of [Na+] on calcification in marine cyanobacteria has not been discussed in detail although [Na+] fluctuations reflect both temperature and sea-level fluctuations. The goal of these lab-scale studies therefore was to study the effect of environmental pH and [Na+] on CaCO3 deposition and dissolution by marine cyanobacterium Phormidium subcapitatum. Marine cyanobacterium P. subcapitatum has been cultivated in ASN-III medium. [Ca2+] fluctuations were monitored with Ca(2+) probe. Na(+) concentrations were determined by the initial solution chemistry. It was found that the balance between CaCO3 dissolution and precipitation induced by P. subcapitatum grown in neutral ASN III medium is very close to zero. No CaCO3 precipitation induced by cyanobacterial growth occurred. Growth of P. subcapitatum in alkaline ASN III medium, however, was accompanied by significant oscillations in free Ca(2+) concentration within a Na(+) concentration range of 50-400 mM. Calcium carbonate precipitation occurred during the log phase of P. subcapitatum growth while carbonate dissolution was typical for the stationary phase of P. subcapitatum growth. The highest CaCO3 deposition was observed in the range of Na(+) concentrations between 200-400 mM. Alkaline pH also induced the clamping of P. subcapitatum filaments, which appeared to have a strong affinity to envelop particles of chemically deposited CaCO3 followed by enlargement of those particles size. EDS analysis revealed the presence of Mg-rich carbonate (or magnesium calcite) in the solution containing 10-100 mM Na(+); calcite in the solution containing 200 mM Na(+); and aragonite in the solution containing with 400 mM Na(+). Typical present-day seawater contains xxmM Na(+). Early (Archean) seawater was likely less saline. The division of marine cyanobacterium P. subcapitatum is associated with periodic deposition and dissolution of CaCO3, the rhythms and intensity of which are dependent on concentrations of both OH(-) and Na(+). Thus, the role of present-day marine cyanobacteria in the global carbonate cycle might be reduced to aggregation and recrystallization of available CaCO3 particles in marine water rather than long-term precipitation and accumulation of CaCO3 deposits. For lower Na(+) concentrations, precipitation of carbonates by cyanobacteria would be even less significant. These results suggest that the lack of calcified cyanobacteria in stromatalite-bearing Precambrian sequences can be explained not only by high dissolved inorganic carbon concentrations but also by lower salinity, as well as possible lower pH compared to present-day oceans.

Changes in Escherichia coli to Cryptosporidium ratios for various fecal pollution sources and drinking water intakes.

PubMed

Lalancette, Cindy; Papineau, Isabelle; Payment, Pierre; Dorner, Sarah; Servais, Pierre; Barbeau, Benoit; Di Giovanni, George D; Prévost, Michèle

2014-05-15

Assessing the presence of human pathogenic Cryptosporidium oocysts in surface water remains a significant water treatment and public health challenge. Most drinking water suppliers rely on fecal indicators, such as the well-established Escherichia coli (E. coli), to avoid costly Cryptosporidium assays. However, the use of E. coli has significant limitations in predicting the concentration, the removal and the transport of Cryptosporidium. This study presents a meta-analysis of E. coli to Cryptosporidium concentration paired ratios to compare their complex relationships in eight municipal wastewater sources, five agricultural fecal pollution sources and at 13 drinking water intakes (DWI) to a risk threshold based on US Environmental Protection Agency (USEPA) regulations. Ratios lower than the USEPA risk threshold suggested higher concentrations of oocysts in relation to E. coli concentrations, revealing an underestimed risk for Cryptosporidium based on E. coli measurements. In raw sewage (RS), high ratios proved E. coli (or fecal coliforms) concentrations were a conservative indicator of Cryptosporidium concentrations, which was also typically true for secondary treated wastewater (TWW). Removals of fecal indicator bacteria (FIB) and parasites were quantified in WWTPs and their differences are put forward as a plausible explanation of the sporadic ratio shift. Ratios measured from agricultural runoff surface water were typically lower than the USEPA risk threshold and within the range of risk misinterpretation. Indeed, heavy precipitation events in the agricultural watershed led to high oocyst concentrations but not to E. coli or enterococci concentrations. More importantly, ratios established in variously impacted DWI from 13 Canadian drinking water plants were found to be related to dominant fecal pollution sources, namely municipal sewage. In most cases, when DWIs were mainly influenced by municipal sewage, E. coli or fecal coliforms concentrations agreed with Cryptosporidium concentrations as estimated by the meta-analysis, but when DWIs were influenced by agricultural runoff or wildlife, there was a poor relationship. Average recovery values were available for 6 out of 22 Cryptosporidium concentration data sets and concomitant analysis demonstrated no changes in trends, with and without correction. Nevertheless, recovery assays performed along with every oocyst count would have enhanced the precision of this work. Based on our findings, the use of annual averages of E. coli concentrations as a surrogate for Cryptosporidium concentrations can result in an inaccurate estimate of the Cryptosporidium risk for agriculture impacted drinking water intakes or for intakes with more distant wastewater sources. Studies of upstream fecal pollution sources are recommended for drinking water suppliers to improve their interpretation of source water quality data. Copyright © 2014 Elsevier Ltd. All rights reserved.

A microliter capillary rheometer for characterization of protein solutions.

PubMed

Hudson, Steven D; Sarangapani, Prasad; Pathak, Jai A; Migler, Kalman B

2015-02-01

Rheometry is an important characterization tool for therapeutic protein solutions because it determines syringeability and relates indirectly to solution stability and thermodynamic interactions. Despite the maturity of rheometry, there remains a need for a rheometer that meets the following three needs of the biopharamaceutical industry: small volume; large dynamic range of shear rates; and no air-sample interface. Here, we report the development of a miniaturized capillary rheometer that meets these needs and is potentially scalable to a multiwell format. These measurements consume only a few microliters of sample and have an uncertainty of a few percent. We demonstrate its performance on monoclonal antibody solutions at different concentrations and temperatures. The instrument has a dynamic range of approximately three decades (in shear rate) and can measure Newtonian, shear thinning, and yielding behaviors, which are representative of the different solution behaviors typically encountered. We compare our microliter capillary rheometer with existing instruments to describe the range of parameter space covered by our device. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

Fresh broad (Vicia faba) tissue homogenate-based biosensor for determination of phenolic compounds.

PubMed

Ozcan, Hakki Mevlut; Sagiroglu, Ayten

2014-08-01

In this study, a novel fresh broad (Vicia faba) tissue homogenate-based biosensor for determination of phenolic compounds was developed. The biosensor was constructed by immobilizing tissue homogenate of fresh broad (Vicia faba) on to glassy carbon electrode. For the stability of the biosensor, general immobilization techniques were used to secure the fresh broad tissue homogenate in gelatin-glutaraldehyde cross-linking matrix. In the optimization and characterization studies, the amount of fresh broad tissue homogenate and gelatin, glutaraldehyde percentage, optimum pH, optimum temperature and optimum buffer concentration, thermal stability, interference effects, linear range, storage stability, repeatability and sample applications (Wine, beer, fruit juices) were also investigated. Besides, the detection ranges of thirteen phenolic compounds were obtained with the help of the calibration graphs. A typical calibration curve for the sensor revealed a linear range of 5-60 μM catechol. In reproducibility studies, variation coefficient (CV) and standard deviation (SD) were calculated as 1.59%, 0.64×10(-3) μM, respectively.

Oxygen measurements at high pressures with vertical cavity surface-emitting lasers

NASA Astrophysics Data System (ADS)

Wang, J.; Sanders, S. T.; Jeffries, J. B.; Hanson, R. K.

Measurements of oxygen concentration at high pressures (to 10.9 bar) were made using diode-laser absorption of oxygen A-band transitions near 760 nm. The wide current-tuning frequency range (>30 cm-1) of vertical cavity surface-emitting lasers (VCSELs) was exploited to enable the first scanned-wavelength demonstration of diode-laser absorption at high pressures; this strategy is more robust than fixed-wavelength strategies, particularly in hostile environments. The wide tuning range and rapid frequency response of the current tuning were further exploited to demonstrate wavelength-modulation absorption spectroscopy in a high-pressure environment. The minimum detectable absorbance demonstrated, 1×10-4, corresponds to 800 ppm-m oxygen detectivity at room temperature and is limited by etalon noise. The rapid- and wide-frequency tunability of VCSELs should significantly expand the application domain of absorption-based sensors limited in the past by the small current-tuning frequency range (typically <2 cm-1) of conventional edge-emitting diode lasers.

Salts in the dry valleys of Antartica

NASA Technical Reports Server (NTRS)

Gibson, E. K., Jr.; Presley, B. J.; Hatfield, J.

1984-01-01

The Dry Valleys of Antarctica are examples of polar deserts which are rare geological features on the Earth. Such deserts typically have high salinities associated with their closed-basin waters and on many surficial materials throughout them. In order to examine the possible sources for the salts observed in association with the soils in the Dry Valleys. The chloride and bromide concentrations of the water leachates from 58 soils and core samples were measured. The Cl/Br ratio for seawater is 289 and ratios measured for most of the 58 soils studied (greater than 85% of the soils studied) was larger than the seawater ratio (ratios typically were greater than 1000 and ranged up to 50,000). The enrichment in Cl relative to Br is strong evidence that the alts present within the soils were derived from seawater during ordinary evaporation processes, and not from the deposition of Cl and Br from aerosols or from rock weathering as has often been suggested.

Sedimentary hydrocarbons and sterols in a South Atlantic estuarine/shallow continental shelf transitional environment under oil terminal and grain port influences.

PubMed

Bet, Rafael; Bícego, Marcia C; Martins, César C

2015-06-15

Sterols and hydrocarbons were determined in the surface sediments from the transitional environment between Paranaguá Bay and the shallow continental shelf in the South Atlantic to assess the sources of organic matter (OM) and the contamination status of an area exposed to multiple anthropogenic inputs. Total aliphatic hydrocarbon concentrations were less than 10μgg(-1), which is typical of unpolluted sediments, and related to recent inputs from higher terrestrial plants. Total polycyclic aromatic hydrocarbon ranged from

Consideration of measurement error when using commercial indoor radon determinations for selecting radon action levels

USGS Publications Warehouse

Reimer, G.M.; Szarzi, S.L.; Dolan, Michael P.

1998-01-01

An examination of year-long, in-home radon measurement in Colorado from commercial companies applying typical methods indicates that considerable variation in precision exists. This variation can have a substantial impact on any mitigation decisions, either voluntary or mandated by law, especially regarding property sale or exchange. Both long-term exposure (nuclear track greater than 90 days), and short-term (charcoal adsorption 4-7 days) exposure methods were used. In addition, periods of continuous monitoring with a highly calibrated alpha-scintillometer took place for accuracy calibration. The results of duplicate commercial analysis show that typical results are no better than ??25 percent with occasional outliers (up to 5 percent of all analyses) well beyond that limit. Differential seasonal measurements (winter/summer) by short-term methods provide equivalent information to single long-term measurements. Action levels in the U.S. for possible mitigation decisions should be selected so that they consider the measurement variability; specifically, they should reflect a concentration range similar to that adopted by the European Community.

Structural aspects of fish skin collagen which forms ordered arrays via liquid crystalline states.

PubMed

Giraud-Guille, M M; Besseau, L; Chopin, C; Durand, P; Herbage, D

2000-05-01

The ability of acid-soluble type I collagen extracts from Soleidae flat fish to form ordered arrays in condensed phases has been compared with data for calf skin collagen. Liquid crystalline assemblies in vitro are optimized by preliminary treatment of the molecular population with ultrasounds. This treatment requires the stability of the fish collagen triple helicity to be controlled by X-ray diffraction and differential scanning calorimetry and the effect of sonication to be evaluated by viscosity measurements and gel electrophoresis. The collagen solution in concentrations of at least 40 mg ml(-1) showed in polarized light microscopy birefringent patterns typical of precholesteric phases indicating long-range order within the fluid collagen phase. Ultrastructural data, obtained after stabilization of the liquid crystalline collagen into a gelated matrix, showed that neutralized acid-soluble fish collagen forms cross-striated fibrils, typical of type I collagen, following sine wave-like undulations in precholesteric domains. These ordered geometries, approximating in vivo situations, give interesting mechanical properties to the material.

Sedimentary loadings and ecological significance of polycyclic aromatic hydrocarbons in a typical mariculture zone of South China.

PubMed

Yu, Huan-Yun; Bao, Lian-Jun; Wong, Charles S; Hu, Yuanan; Zeng, Eddy Y

2012-10-26

Two sediment cores were collected from Hailing Bay located in a typical mariculture zone of Guangdong Province, South China, and analyzed for polycyclic aromatic hydrocarbons (PAHs). The concentrations of the sum of 27 PAHs ranged from 62 to 1200 ng g(-1) dry wt, and sediment in the study area was considered to be moderately polluted by PAHs. Source diagnostics based on PAH composition and principal component analysis suggested that PAHs in the study area were mainly derived from petroleum combustion, with discharge of PAHs from fishing boats as an important source. Ecological risk assessment results indicate that PAHs in sediment of the present study currently have minimal adverse effect on the mariculture environment. Comparison of sedimentary inventory of PAHs in the fish harbor of the study area with those in the Pearl River Estuary and the coastal Bohai Bay indicate that the sediment has become an important reservoir of PAHs.

Sodium Sulfate Separation from Aqueous Alkaline Solutions via Crystalline Urea-Functionalized Capsules: Thermodynamics and Kinetics of Crystallization

DOE PAGES

Custelcean, Radu; Sloop, Frederick V.; Rajbanshi, Arbin; ...

2014-12-04

We measured the thermodynamics and kinetics of crystallization of sodium sulfate with a tripodal tris-urea receptor (L1) from aqueous alkaline solutions in the 15 55 C temperature range, with the goal of identifying the optimal conditions for efficient and quick sulfate removal from nuclear wastes. The use of radiolabeled Na 2 35SO 4 provided a practical way to monitor the sulfate concentration in solution by liquid scintillation counting. Our results are consistent with a two-step crystallization mechanism, involving relatively quick dissolution of crystalline L1 followed by the rate-limiting crystallization of the Na 2SO 4(L1) 2(H 2O) 4 capsules. We foundmore » that temperature exerted relatively little influence over the equilibrium sulfate concentration, which ranged between 0.004 and 0.011 M. Moreover, this corresponds to 77 91% removal of sulfate from a solution containing 0.0475 M initial sulfate concentration, as found in a typical Hanford waste tank. The apparent pseudo-first-order rate constant for sulfate removal increased 20-fold from 15 to 55 C, corresponding to an activation energy of 14.1 kcal/mol. At the highest measured temperature of 55 C, 63% and 75% of sulfate was removed from solution within 8 h and 24 h, respectively.« less

Hepatitis E in blood donors: investigation of the natural course of asymptomatic infection, Germany, 2011.

PubMed

Vollmer, Tanja; Diekmann, Juergen; Eberhardt, Matthias; Knabbe, Cornelius; Dreier, Jens

2016-09-01

Asymptomatic hepatitis E virus (HEV) infections have been found in blood donors from various European countries, but the natural course is rarely specified. Here, we compared the progression of HEV viraemia, serostatus and liver-specific enzymes in 10 blood donors with clinically asymptomatic genotype 3 HEV infection, measuring HEV RNA concentrations, plasma concentrations of alanine/aspartate aminotransferase, glutamate dehydrogenase and bilirubin and anti-HEV IgA, IgM and IgG antibodies. RNA concentrations ranged from 77.2 to 2.19×10(5) IU/mL, with viraemia lasting from less than 10 to 52 days. Donors showed a typical progression of a recent HEV infection but differed in the first detection of anti-HEV IgA, IgM and IgG and seropositivity of the antibody classes. The diagnostic window between HEV RNA detection and first occurrence of anti-HEV antibodies ranged from eight to 48 days, depending on the serological assay used. The progression of laboratory parameters of asymptomatic HEV infection was largely comparable to the progression of symptomatic HEV infection, but only four of 10 donors showed elevated liver-specific parameters. Our results help elucidate the risk of transfusion-associated HEV infection and provide a basis for development of screening strategies. The diagnostic window illustrates that infectious blood donors can be efficiently identified only by RNA screening. This article is copyright of The Authors, 2016.

Elevated carbon dioxide influences yield and photosynthetic responses of hydroponically-grown sweetpotato

NASA Technical Reports Server (NTRS)

Mortley, D.; Hill, J.; Loretan, P.; Bonsi, C.; Hill, W.; Hileman, D.; Terse, A.

1996-01-01

The response of 'TI-155' and 'Georgia Jet' sweetpotato cultivars to elevated CO2 concentrations of 400 (ambient), 750 and 1000 micromoles mol-1 were evaluated under controlled environment conditions using the nutrient film technique (NFT). Growth chamber conditions included photosynthetic photon flux (PPF) of 600 micromoles m-2 s-1, 14/10 light/dark period, and 70% +/- 5% RH. Plants were grown using a modified half-Hoagland nutrient solution with a pH range of 5.5-6.0 and an electrical conductivity of 0.12 S m-1. Gas exchange measurements were made using infrared gas analysis, an open-flow gas exchange system, and a controlled-climate cuvette. Photosynthetic (Pn) measurements were made at CO2 ranges of 50 to 1000 micromoles mol-1. Storage root yield/plant increased with CO2 up to 750 but declined at 1000 micromoles mol-1. Storage root dry matter (DM) and foliage dry weight increased with increasing CO2. Harvest index (HI) for both cultivars was highest at 750 micromoles mol-1. The PPF vs Pn curves were typical for C3 plants with saturation occurring at approximately 600 micromoles m-2 s-1. CO2 concentration did not significantly influence net Pn, transpiration, water-use-efficiency (WUE), and stomatal conductance. As measurement CO2 concentration increased, net Pn and WUE increased while transpiration and stomatal conductance decreased.

Real-time measurement of individual occupational radon exposures in tombs of the Valley of the Kings, Egypt.

PubMed

Gruber, E; Salama, E; Rühm, W

2011-03-01

The active radon exposure meter developed recently at the German Research Center for Environmental Health (Helmholtz Zentrum München) was used to measure radon concentrations in 12 tombs located in the Valley of the Kings, Egypt. Radon concentrations in air between 50 ± 7 and 12 100 ± 600 Bq m(-3) were obtained. The device was also used to measure individual radon exposures of those persons working as safeguards inside the tombs. For a measurement time of 2-3 d, typical individual radon exposures ranged from 1800 ± 400 to 240 000 ± 13 000 Bq h m(-3), depending on the duration of measurement and radon concentration in the different tombs. Based on current ICRP dose conversion conventions for workers and on equilibrium factors published in the literature for these tombs, individual effective dose rates that range from 1.5 ± 0.3 to 860 ± 50 µSv d(-1) were estimated. If it is assumed that the climatic conditions present at the measurement campaign persist for about half a year, in this area, then effective doses up to ∼ 66 mSv could be estimated for half a year, for some of the safeguards of tombs where F-values were known. To reduce the exposure of the safeguards, some recommendations are proposed.

Method of analysis and quality-assurance practices by the U.S. Geological Survey Organic Geochemistry Research Group; determination of geosmin and methylisoborneol in water using solid-phase microextraction and gas chromatography/mass spectrometry

USGS Publications Warehouse

Zimmerman, L.R.; Ziegler, A.C.; Thurman, E.M.

2002-01-01

A method for the determination of two common odor-causing compounds in water, geosmin and 2-methylisoborneol, was modified and verified by the U.S. Geological Survey's Organic Geochemistry Research Group in Lawrence, Kansas. The optimized method involves the extraction of odor-causing compounds from filtered water samples using a divinylbenzene-carboxen-polydimethylsiloxane cross-link coated solid-phase microextraction (SPME) fiber. Detection of the compounds is accomplished using capillary-column gas chromatography/mass spectrometry (GC/MS). Precision and accuracy were demonstrated using reagent-water, surface-water, and ground-water samples. The mean accuracies as percentages of the true compound concentrations from water samples spiked at 10 and 35 nanograms per liter ranged from 60 to 123 percent for geosmin and from 90 to 96 percent for 2-methylisoborneol. Method detection limits were 1.9 nanograms per liter for geosmin and 2.0 nanograms per liter for 2-methylisoborneol in 45-milliliter samples. Typically, concentrations of 30 and 10 nanograms per liter of geosmin and 2-methylisoborneol, respectively, can be detected by the general public. The calibration range for the method is equivalent to concentrations from 5 to 100 nanograms per liter without dilution. The method is valuable for acquiring information about the production and fate of these odor-causing compounds in water.

Criteria for assessing the ecological risk of nonylphenol for aquatic life in Chinese surface fresh water.

PubMed

Zhang, Liangmao; Wei, Caidi; Zhang, Hui; Song, Mingwei

2017-10-01

The typical environmental endocrine disruptor nonylphenol is becoming an increasingly common pollutant in both fresh and salt water; it compromises the growth and development of many aquatic organisms. As yet, water quality criteria with respect to nonylphenol pollution have not been established in China. Here, the predicted "no effect concentration" of nonylphenol was derived from an analysis of species sensitivity distribution covering a range of species mainly native to China, as a means of quantifying the ecological risk of nonylphenol in surface fresh water. The resulting model, based on the log-logistic distribution, proved to be robust; the minimum sample sizes required for generating a stable estimate of HC 5 were 12 for acute toxicity and 13 for chronic toxicity. The criteria maximum concentration and criteria continuous concentration were, respectively 18.49 μg L -1 and 1.85 μg L -1 . Among the 24 sites surveyed, two were associated with a high ecological risk (risk quotient >1) and 12 with a moderate ecological risk (risk quotient >0.1). The potentially affected fraction ranged from 0.008% to 24.600%. The analysis provides a theoretical basis for both short- and long-term risk assessments with respect to nonylphenol, and also a means to quantify the risk to aquatic ecosystems. Copyright © 2017 Elsevier Ltd. All rights reserved.

Kinetics of the oxidation of hydrogen sulfite by hydrogen peroxide in aqueous solution:. ionic strength effects and temperature dependence

NASA Astrophysics Data System (ADS)

Maaß, Frank; Elias, Horst; Wannowius, Klaus J.

Conductometry was used to study the kinetics of the oxidation of hydrogen sulfite, HSO -3, by hydrogen peroxide in aqueous non-buffered solution at the low concentration level of 10 -5-10 -6 M, typically found in cloud water. The kinetic data confirm that the rate law reported for the pH range 3-6 at higher concentration levels, rate= kH·[H +]·[HSO -3]·[H 2O 2], is valid at the low concentration level and at low ionic strength Ic. At 298 K and Ic=1.5×10 -4 M, third-order rate constant kH was found to be kH=(9.1±0.5)×10 7 M -2 s -1. The temperature dependence of kH led to an activation energy of Ea=29.7±0.9 kJ mol -1. The effect of the ionic strength (adjusted with NaCl) on rate constant kH was studied in the range Ic=2×10 -4-5.0 M at pH=4.5-5.2 by conductometry and stopped-flow spectrophotometry. The dependence of kH on Ic can be described with a semi-empirical relationship, which is useful for the purpose of comparison and extrapolation. The kinetic data obtained are critically compared with those reported earlier.

Fiber-Optic Coupled Lidar Receiver System to Measure Stratospheric Ozone

NASA Technical Reports Server (NTRS)

Harper, David Brent; Elsayed-Ali, Hani

1998-01-01

The measurement of ozone in the atmosphere has become increasingly important over the past two decades. Significant increases of ozone concentrations in the lower atmosphere, or troposphere, and decreases in the upper atmosphere, or stratosphere, have been attributed to man-made causes. High ozone concentrations in the troposphere pose a health hazard to plants and animals and can add to global warming. On the other hand, ozone in the stratosphere serves as a protective barrier against strong ultraviolet (UV) radiation from the sun. Man-made CFC's (chlorofluorocarbons) act as a catalyst with a free oxygen atom and an ozone molecule to produce two oxygen molecules therefore depleting the protective layer of ozone in the stratosphere. The beneficial and harmful effects of ozone require the study of ozone creation and destruction processes in the atmosphere. Therefore, to provide an accurate model of these processes, an ozone lidar system must be able to be used frequently with as large a measurement range as possible. Various methods can be used to measure atmospheric ozone concentrations. These include different airborne and balloon measurements, solar occulation satellite techniques, and the use of lasers in lidar (high detection and ranging,) systems to probe the atmosphere. Typical devices such as weather balloons can only measure within the direct vicinity of the instrument and are therefore used infrequently. Satellites use solar occulation techniques that yield low horizontal and vertical resolution column densities of ozone.

Quality of water in domestic wells in the Chicot and Chicot equivalent aquifer systems, southern Louisiana and southwestern Mississippi, 2000-2001

USGS Publications Warehouse

Tollett, Roland W.; Fendick, Robert B.; Simmons, Lane B.

2003-01-01

In 2000-2001, water-quality data were collected from 60 randomly selected domestic wells in the Acadian-Pontchartrain Study Unit, as part of the National Water-Quality Assessment Program. The data were collected from wells screened in shallow sands (less than 350 feet below land surface) in two major aquifer systems--the Chicot aquifer system in southwestern Louisiana and the Chicot equivalent aquifer system in southeastern Louisiana and southwestern Mississippi. The Chicot equivalent aquifer system is part of the Southern Hills regional aquifer system, and both the Chicot aquifer system and the Southern Hills regional aquifer systems are designated as sole-source aquifers by the U.S. Environmental Protection Agency (USEPA). The well depths ranged from 40 to 340 feet below land surface with a median depth of 120 feet. The ground-water-quality data included 5 physiochemical properties, dissolved solids, 9 major inorganic ions, 24 trace elements, 6 nutrients, dissolved organic carbon, 109 pesticides and degradation products, and 85 volatile organic compounds (VOC's); and a subset of the wells were sampled for radon, chlorofluorocarbons, and stable isotopes. Water from 35 of the 60 domestic wells sampled had pH values less than the USEPA Seconday Maximum Contaminant Level (SMCL) range of 6.5 to 8.5 standard units. Specific conductance ranged from 17 to 1,420 microsiemens per centimeter at 25 degrees Celsius. Dissolved-solids concentrations in water from two wells exceeded the SMCL of 500 mg/L (milligrams per liter); the maximum concentration was 858 mg/L. Sodium and calcium were the dominant cations, and bicarbonate and chloride were the dominant anions. One chloride concentration (264 mg/L) exceeded the SMCL of 250 mg/L. One arsenic concentration (55.3 micrograms per liter) exceeded the USEPA Maximum Contaminant Level (MCL) of 10 micrograms per liter. Iron concentrations in water from 22 wells exceeded the SMCL of 300 micrograms per liter; the maximum concentration was 8,670 micrograms per liter. Manganese concentrations in water from 26 wells exceeded the SMCL of 50 micrograms per liter; the maximum concentration was 481 micrograms per liter. Health Advisories have been established for six of the trace elements analyzed; no concentrations were greater than these nonenforceable standards. Radon concentrations in water from 9 of 50 wells sampled were greater thanthe proposed USEPA MCL of 300 picocuries per liter. Concentrations of ammonia, ammonia plus organic nitrogen, and nitrite plus nitrate in water from four wells were greater than 2 mg/L, a level that might indicate anthropogenic influences. The median dissolved organic carbon concentration was an estimated 0.30 mg/L, which indicated naturally occurring dissolved organic carbon conditions in the study area. Eight pesticides and two degradation products were detected in water from five wells. Twenty-four VOC's were detected in water from 44 wells. All concentrations of pesticides and VOC's were less than USEPA drinking-water standards. Quality-control samples, which included field-blank samples, replicates, and field and laboratory spikes, indicated no bias in ground-water data from collection procedures or analyses. VAriance between the environmental sampls and he corresponding replicate samples was typically less than 5 percent, indicating and acceptable degree of laboratory precision and data collection reproducibility. The Mann-Whitney rank-sum test was used to compare depth to top of screen and selected physicochemical properties and chemical constituents between six groups of wells. Values for selected physicochemical and chemical constituents were typically greater in wells located in the Chicot aquifer system than in the Chicot equivalent aquifer system. Values for specific conductance, pH, calcium, sodium, bicarbonate, chloride, dis

[Mercury Transport from Glacier to Runoff in Typical Inland Glacial Area in the Tibetan Plateau].

PubMed

Sun, Xue-jun; Wang, Kang; Guo, Jun-ming; Kang, Shi-chang; Zhang, Guo-shuai; Huang, Jie; Cong, Zhi-yuan; Zhang, Qiang-gong

2016-02-15

To investigate the transport of mercury from glacier to runoff in typical inland glacial area in the Tibetan Plateau, we selected Zhadang glacier and Qugaqie river Basin located in the Nyainqentanglha Range region and collected samples from snow pit, glacier melt-water and Qugaqie river water during 15th August to 9'h September 2011. Mercury speciation and concentrations were determined and their distribution and controlling factors in different environmental compartments were analyzed. The results showed that the average THg concentrations were (3.79 +/- 5.12) ng x L(-1), (1.06 +/- 0.77) ng x L(-1) and (1.02 +/- 0.24) ng x L(-1) for glacier snow, glacier melt-water and Qugaqie river water, respectively, all of which were at the global background levels. Particulate-bound mercury accounted for large proportion of mercury in all environmental matrices, while mercury in glacial melt-water was controlled by total suspended particle, and mercury in Qugaqie river water co-varied with runoff. With the increase of temperature, glacier melted and released water as well as mercury into glacier-fed river. Total mercury concentrations in glacier melt water, upstream and downstream peaked at 14:00, 16:00 and after 20:00, respectively, reflecting the process of mercury release from glacier and its subsequent transport in the glacier fed river. The transport of riverine mercury was controlled by multiple factors. Under the context of climate change, glacier ablation and the increasing runoff will play increasingly important roles in mercury release and transport.

Temporal patterns, sources, and sinks of C8-C16 hydrocarbons in the atmosphere of Mace Head, Ireland

NASA Astrophysics Data System (ADS)

Sartin, , J. H.; Halsall, , C. J.; Robertson, , L. A.; Gonard, , R. G.; MacKenzie, , A. R.; Berresheim, , H.; Hewitt, C. N.

2002-10-01

During the 1999 New Particle Formation and Fate in the Coastal Environment (PARFORCE) field campaign, 16 C8-C16 volatile organic compounds (VOCs) were identified in the coastal atmosphere of Mace Head, Ireland. Sampling took place over 24 days, with 12 VOCs routinely quantified. Concentrations were observed in the low <10-150 parts per trillion by volume range, with levels typically in the order of aldehydes > ketones ≥ n-alkanes. Concentrations of these compounds were also measured in shoreline surface seawater. No relationship was observed between atmospheric concentrations and high/low tide events. Many VOCs revealed a temporal pattern in the atmosphere, with highest concentrations measured during the early morning and lowest concentrations in the afternoon. The strongest pattern was observed for the n-alkanes. However, this was dependent on the prevailing air mass direction and the local meteorology. A Lagrangian box model was applied to assess this diurnal cycle, using seawater emissions as a source (based on the seawater concentrations and observed wind speeds), and depletion via OH radicals and dilution by entrainment as sinks (using measured [OH] and boundary layer height data). The model gave good agreement to the observed concentrations for selected air mass types, predicting the daytime decrease in VOC concentrations due to OH radical chemistry and boundary layer growth, and the subsequent increase in VOC concentrations toward evening as both oxidation chemistry diminished and the mixing layer height fell.

C60 Cheese Sticks: Supramolecular Architecture of an Amphiphilic Fullerene Pentapod.

PubMed

Samal, Monica; Acharya, Sandhyarani; Yi, Dong Kee; Lee, Jae-Suk; Samal, Shashadhar

2015-09-01

An amphiphillic fullerene pentaphenol derivative, C60(4-HOC6H4)5H, in an aprotic solvent N-methyl-2-pyrrolidone (NMP), spontaneously self-assembles to a hitherto unknown cheese stick-like (CS) structure. This fascinating structure is observed only for C60(4-HOC6H4)5H and only in dry NMP solvent. The reason for such unique self-assembly behavior is ascribed to solvating power typical of NMP. The CS structure is observed in a narrow concentration range of the solution. This indicates that there exists between the solute and the solvent an optimal interaction condition for CS to remain stable.

Secondary organic aerosol formation from ambient air in an oxidation flow reactor in central Amazonia

DOE PAGES

Palm, Brett B.; de Sá, Suzane S.; Day, Douglas A.; ...

2018-01-17

Secondary organic aerosol (SOA) formation from ambient air was studied using an oxidation flow reactor (OFR) coupled to an aerosol mass spectrometer (AMS) during both the wet and dry seasons at the Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) field campaign. Measurements were made at two sites downwind of the city of Manaus, Brazil. Ambient air was oxidized in the OFR using variable concentrations of either OH or O 3, over ranges from hours to days (O 3) or weeks (OH) of equivalent atmospheric aging. The amount of SOA formed in the OFR ranged from 0 to asmore » much as 10 μg m -3, depending on the amount of SOA precursor gases in ambient air. Typically, more SOA was formed during nighttime than daytime, and more from OH than from O 3 oxidation. SOA yields of individual organic precursors under OFR conditions were measured by standard addition into ambient air, and confirmed to be consistent with published environmental chamber-derived SOA yields. Positive matrix factorization of organic aerosol (OA) after OH oxidation showed formation of typical oxidized OA factors and a loss of primary OA factors as OH aging increased. After OH oxidation in the OFR, the hygroscopicity of the OA increased with increasing elemental O : C up to O : C ~ 1.0, and then decreased as O : C increased further. Some possible reasons for this decrease are discussed. The measured SOA formation was compared to the amount predicted from the concentrations of measured ambient SOA precursors and their SOA yields. And while measured ambient precursors were sufficient to explain the amount of SOA formed from O 3, they could only explain 10–50 % of the SOA formed from OH. This is consistent with previous OFR studies which showed that typically unmeasured semivolatile and intermediate volatility gases (that tend to lack C = C bonds) are present in ambient air and can explain such additional SOA formation. To investigate the sources of the unmeasured SOA-forming gases during this campaign, multilinear regression analysis was performed between measured SOA formation and the concentration of gas-phase tracers representing different precursor sources. The majority of SOA-forming gases present during both seasons were of biogenic origin. Urban sources also contributed substantially in both seasons, while biomass burning sources were more important during the dry season. Our study enables a better understanding of SOA formation in environments with diverse emission sources.« less

Secondary organic aerosol formation from ambient air in an oxidation flow reactor in central Amazonia

NASA Astrophysics Data System (ADS)

Palm, Brett B.; de Sá, Suzane S.; Day, Douglas A.; Campuzano-Jost, Pedro; Hu, Weiwei; Seco, Roger; Sjostedt, Steven J.; Park, Jeong-Hoo; Guenther, Alex B.; Kim, Saewung; Brito, Joel; Wurm, Florian; Artaxo, Paulo; Thalman, Ryan; Wang, Jian; Yee, Lindsay D.; Wernis, Rebecca; Isaacman-VanWertz, Gabriel; Goldstein, Allen H.; Liu, Yingjun; Springston, Stephen R.; Souza, Rodrigo; Newburn, Matt K.; Lizabeth Alexander, M.; Martin, Scot T.; Jimenez, Jose L.

2018-01-01

Secondary organic aerosol (SOA) formation from ambient air was studied using an oxidation flow reactor (OFR) coupled to an aerosol mass spectrometer (AMS) during both the wet and dry seasons at the Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) field campaign. Measurements were made at two sites downwind of the city of Manaus, Brazil. Ambient air was oxidized in the OFR using variable concentrations of either OH or O3, over ranges from hours to days (O3) or weeks (OH) of equivalent atmospheric aging. The amount of SOA formed in the OFR ranged from 0 to as much as 10 µg m-3, depending on the amount of SOA precursor gases in ambient air. Typically, more SOA was formed during nighttime than daytime, and more from OH than from O3 oxidation. SOA yields of individual organic precursors under OFR conditions were measured by standard addition into ambient air and were confirmed to be consistent with published environmental chamber-derived SOA yields. Positive matrix factorization of organic aerosol (OA) after OH oxidation showed formation of typical oxidized OA factors and a loss of primary OA factors as OH aging increased. After OH oxidation in the OFR, the hygroscopicity of the OA increased with increasing elemental O : C up to O : C ˜ 1.0, and then decreased as O : C increased further. Possible reasons for this decrease are discussed. The measured SOA formation was compared to the amount predicted from the concentrations of measured ambient SOA precursors and their SOA yields. While measured ambient precursors were sufficient to explain the amount of SOA formed from O3, they could only explain 10-50 % of the SOA formed from OH. This is consistent with previous OFR studies, which showed that typically unmeasured semivolatile and intermediate volatility gases (that tend to lack C = C bonds) are present in ambient air and can explain such additional SOA formation. To investigate the sources of the unmeasured SOA-forming gases during this campaign, multilinear regression analysis was performed between measured SOA formation and the concentration of gas-phase tracers representing different precursor sources. The majority of SOA-forming gases present during both seasons were of biogenic origin. Urban sources also contributed substantially in both seasons, while biomass burning sources were more important during the dry season. This study enables a better understanding of SOA formation in environments with diverse emission sources.

Precipitation-runoff relations and water-quality characteristics at edge-of-field stations, Discovery Farms and Pioneer Farm, Wisconsin, 2003-8

USGS Publications Warehouse

Stuntebeck, Todd D.; Komiskey, Matthew J.; Peppler, Marie C.; Owens, David W.; Frame, Dennis R.

2011-01-01

A cooperative study between the U.S. Geological Survey, the University of Wisconsin (UW)-Madison Discovery Farms program (Discovery Farms), and the UW-Platteville Pioneer Farm program (Pioneer Farm) was developed to identify typical ranges and magnitudes, temporal distributions, and principal factors affecting concentrations and yields of sediment, nutrients, and other selected constituents in runoff from agricultural fields. Hydrologic and water-quality data were collected year-round at 23 edge-of-field monitoring stations on 5 privately owned Discovery Farms and on Pioneer Farm during water years 2003-8. The studied farms represented landscapes, soils, and farming systems typical of livestock farms throughout southern Wisconsin. Each farm employed a variety of soil, nutrient, and water-conservation practices to help minimize sediment and nutrient losses from fields and to improve crop productivity. This report summarizes the precipitation-runoff relations and water-quality characteristics measured in edge-of-field runoff for 26 "farm years" (aggregate years of averaged station data from all 6 farms for varying monitoring periods). A relatively wide range of constituents typically found in agricultural runoff were measured: suspended sediment, phosphorus (total, particulate, dissolved reactive, and total dissolved), and nitrogen (total, nitrate plus nitrite, organic, ammonium, total Kjeldahl and total Kjeldahl-dissolved), chloride, total solids, total suspended solids, total volatile suspended solids, and total dissolved solids. Mean annual precipitation was 32.8 inches for the study period, about 3 percent less than the 30-year mean. Overall mean annual runoff was 2.55 inches per year (about 8 percent of precipitation) and the distribution was nearly equal between periods of frozen ground (54 percent) and unfrozen ground (46 percent). Mean monthly runoff was highest during two periods: February to March and May to June. Ninety percent of annual runoff occurred between January and the end of June. Event mean concentrations of suspended sediment in runoff during unfrozen-ground periods were significantly higher (p2= 0.92), indicating that the sources of nitrogen and phosphorus in runoff were likely similar. Analysis of runoff, concentration, and yield data on annual, monthly, and seasonal time scales, when combined with precipitation, soil moisture, soil temperature, and on-farm field-activity information, revealed conditions in which runoff was most likely. The analysis also revealed the effects that field conditions and the timing of field-management activities-most notably, manure applications and tillage-had on the quantity and quality of surface runoff from agricultural fields.

Secondary organic aerosol formation from ambient air in an oxidation flow reactor in central Amazonia

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

Palm, Brett B.; de Sá, Suzane S.; Day, Douglas A.

Secondary organic aerosol (SOA) formation from ambient air was studied using an oxidation flow reactor (OFR) coupled to an aerosol mass spectrometer (AMS) during both the wet and dry seasons at the Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) field campaign. Measurements were made at two sites downwind of the city of Manaus, Brazil. Ambient air was oxidized in the OFR using variable concentrations of either OH or O 3, over ranges from hours to days (O 3) or weeks (OH) of equivalent atmospheric aging. The amount of SOA formed in the OFR ranged from 0 to asmore » much as 10 μg m -3, depending on the amount of SOA precursor gases in ambient air. Typically, more SOA was formed during nighttime than daytime, and more from OH than from O 3 oxidation. SOA yields of individual organic precursors under OFR conditions were measured by standard addition into ambient air, and confirmed to be consistent with published environmental chamber-derived SOA yields. Positive matrix factorization of organic aerosol (OA) after OH oxidation showed formation of typical oxidized OA factors and a loss of primary OA factors as OH aging increased. After OH oxidation in the OFR, the hygroscopicity of the OA increased with increasing elemental O : C up to O : C ~ 1.0, and then decreased as O : C increased further. Some possible reasons for this decrease are discussed. The measured SOA formation was compared to the amount predicted from the concentrations of measured ambient SOA precursors and their SOA yields. And while measured ambient precursors were sufficient to explain the amount of SOA formed from O 3, they could only explain 10–50 % of the SOA formed from OH. This is consistent with previous OFR studies which showed that typically unmeasured semivolatile and intermediate volatility gases (that tend to lack C = C bonds) are present in ambient air and can explain such additional SOA formation. To investigate the sources of the unmeasured SOA-forming gases during this campaign, multilinear regression analysis was performed between measured SOA formation and the concentration of gas-phase tracers representing different precursor sources. The majority of SOA-forming gases present during both seasons were of biogenic origin. Urban sources also contributed substantially in both seasons, while biomass burning sources were more important during the dry season. Our study enables a better understanding of SOA formation in environments with diverse emission sources.« less

Secondary organic aerosol formation from ambient air in an oxidation flow reactor in central Amazonia

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

Palm, Brett B.; de Sá, Suzane S.; Day, Douglas A.

Secondary organic aerosol (SOA) formation from ambient air was studied using an oxidation flow reactor (OFR) coupled to an aerosol mass spectrometer (AMS) during both the wet and dry seasons at the Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) field campaign. Measurements were made at two sites downwind of the city of Manaus, Brazil. Ambient air was oxidized in the OFR using variable concentrations of either OH or O 3, over ranges from hours to days (O 3) or weeks (OH) of equivalent atmospheric aging. The amount of SOA formed in the OFR ranged from 0 to asmore » much as 10 µg m −3, depending on the amount of SOA precursor gases in ambient air. Typically, more SOA was formed during nighttime than daytime, and more from OH than from O 3 oxidation. SOA yields of individual organic precursors under OFR conditions were measured by standard addition into ambient air and were confirmed to be consistent with published environmental chamber-derived SOA yields. Positive matrix factorization of organic aerosol (OA) after OH oxidation showed formation of typical oxidized OA factors and a loss of primary OA factors as OH aging increased. After OH oxidation in the OFR, the hygroscopicity of the OA increased with increasing elemental O : C up to O : C ∼ 1.0, and then decreased as O : C increased further. Possible reasons for this decrease are discussed. The measured SOA formation was compared to the amount predicted from the concentrations of measured ambient SOA precursors and their SOA yields. While measured ambient precursors were sufficient to explain the amount of SOA formed from O 3, they could only explain 10–50 % of the SOA formed from OH. This is consistent with previous OFR studies, which showed that typically unmeasured semivolatile and intermediate volatility gases (that tend to lack C = C bonds) are present in ambient air and can explain such additional SOA formation. To investigate the sources of the unmeasured SOA-forming gases during this campaign, multilinear regression analysis was performed between measured SOA formation and the concentration of gas-phase tracers representing different precursor sources. The majority of SOA-forming gases present during both seasons were of biogenic origin. Urban sources also contributed substantially in both seasons, while biomass burning sources were more important during the dry season. This study enables a better understanding of SOA formation in environments with diverse emission sources.« less

Utilization of extracellular information before ligand-receptor binding reaches equilibrium expands and shifts the input dynamic range

PubMed Central

Ventura, Alejandra C.; Bush, Alan; Vasen, Gustavo; Goldín, Matías A.; Burkinshaw, Brianne; Bhattacharjee, Nirveek; Folch, Albert; Brent, Roger; Chernomoretz, Ariel; Colman-Lerner, Alejandro

2014-01-01

Cell signaling systems sense and respond to ligands that bind cell surface receptors. These systems often respond to changes in the concentration of extracellular ligand more rapidly than the ligand equilibrates with its receptor. We demonstrate, by modeling and experiment, a general “systems level” mechanism cells use to take advantage of the information present in the early signal, before receptor binding reaches a new steady state. This mechanism, pre-equilibrium sensing and signaling (PRESS), operates in signaling systems in which the kinetics of ligand-receptor binding are slower than the downstream signaling steps, and it typically involves transient activation of a downstream step. In the systems where it operates, PRESS expands and shifts the input dynamic range, allowing cells to make different responses to ligand concentrations so high as to be otherwise indistinguishable. Specifically, we show that PRESS applies to the yeast directional polarization in response to pheromone gradients. Consideration of preexisting kinetic data for ligand-receptor interactions suggests that PRESS operates in many cell signaling systems throughout biology. The same mechanism may also operate at other levels in signaling systems in which a slow activation step couples to a faster downstream step. PMID:25172920

Colorimetric detection of catalytic reactivity of nanoparticles in complex matrices.

PubMed

Corredor, Charlie; Borysiak, Mark D; Wolfer, Jay; Westerhoff, Paul; Posner, Jonathan D

2015-03-17

There is a need for new methodologies to quickly assess the presence and reactivity of nanoparticles (NPs) in commercial, environmental, and biological samples since current detection techniques require expensive and complex analytical instrumentation. Here, we investigate a simple and portable colorimetric detection assay that assesses the surface reactivity of NPs, which can be used to detect the presence of NPs, in complex matrices (e.g., environmental waters, serum, urine, and in dissolved organic matter) at as low as part per billion (ppb) or ng/mL concentration levels. Surface redox reactivity is a key emerging property related to potential toxicity of NPs with living cells, and is used in our assays as a key surrogate for the presence of NPs and a first tier analytical strategy toward assessing NP exposures. We detect a wide range of metal (e.g., Ag and Au) and oxide (e.g., CeO2, SiO2, VO2) NPs with a diameter range of 5 to 400 nm and multiple capping agents (tannic acid (TA), polyvinylpyrrolidone (PVP), branched polyethylenimine (BPEI), polyethylene glycol (PEG)). This method is sufficiently sensitive (ppb levels) to measure concentrations typically used in toxicological studies, and uses inexpensive, commercially available reagents.

Chlorine Abundances in Martian Meteorites

NASA Technical Reports Server (NTRS)

Bogard, D.D.; Garrison, D.H.; Park, J.

2009-01-01

Chlorine measurements made in martian surface rocks by robotic spacecraft typically give Chlorine (Cl) abundances of approximately 0.1-0.8%. In contrast, Cl abundances in martian meteorites appear lower, although data is limited, and martian nakhlites were also subjected to Cl contamination by Mars surface brines. Chlorine abundances reported by one lab for whole rock (WR) samples of Shergotty, ALH77005, and EET79001 range 108-14 ppm, whereas Cl in nakhlites range 73-1900 ppm. Measurements of Cl in various martian weathering phases of nakhlites varied 0.04-4.7% and reveal significant concentration of Cl by martian brines Martian meteorites contain much lower Chlorine than those measured in martian surface rocks and give further confirmation that Cl in these surface rocks was introduced by brines and weathering. It has been argued that Cl is twice as effective as water in lowering the melting point and promoting melting at shallower martian depths, and that significant Cl in the shergottite source region would negate any need for significant water. However, this conclusion was based on experiments that utilized Cl concentrations more analogous to martian surface rocks than to shergottite meteorites, and may not be applicable to shergottites.

Field-rugged sensitive hydrogen peroxide sensor based on tunable diode laser absorption spectroscopy (TDLAS)

NASA Astrophysics Data System (ADS)

Frish, M. B.; Morency, J. R.; Laderer, M. C.; Wainner, R. T.; Parameswaran, K. R.; Kessler, W. J.; Druy, M. A.

2010-04-01

This paper reports the development and initial testing of a field-portable sensor for monitoring hydrogen peroxide (H2O2) and water (H2O) vapor concentrations during building decontamination after accidental or purposeful exposure to hazardous biological materials. During decontamination, a sterilization system fills ambient air with water and peroxide vapor to near-saturation. The peroxide concentration typically exceeds several hundred ppm for tens of minutes, and subsequently diminishes below 1 ppm. The H2O2/ H2O sensor is an adaptation of a portable gas-sensing platform based on Tunable Diode Laser Absorption Spectroscopy (TDLAS) technology. By capitalizing on its spectral resolution, the TDLAS analyzer isolates H2O2 and H2O spectral lines to measure both vapors using a single laser source. It offers a combination of sensitivity, specificity, fast response, dynamic range, linearity, ease of operation and calibration, ruggedness, and portability not available in alternative H2O2 detectors. The H2O2 range is approximately 0- 5,000 ppm. The autonomous and rugged instrument provides real-time data. It has been tested in a closed-loop liquid/vapor equilibrium apparatus and by comparison against electrochemical sensors.

The presence of natural radioactivity and 137Cs in the South China Sea bordering peninsular Malaysia.

PubMed

Amin, Y M; Mahat, R H; Nor, R M; Khandaker, Mayeen Uddin; Takleef, Ghazwa Hatem; Bradley, D A

2013-10-01

The presence of natural radioactivity and (137)Cs has been investigated in fresh media obtained from South China Sea locations off the coast of peninsular Malaysia. The media include seafood, sea water and sediment. The samples were collected some weeks prior to the devastating 2011 Tōhoku earthquake and associated tsunami, the occurrence of which precipitated the Fukushima incident. All samples showed the presence of naturally occurring (226)Ra, (228)Ra and primordial (40)K, all at typically prevailing levels. The concentrations of natural radioactivity in molluscs were found to be greater than that of other marine life studied herein, the total activity ranging from 337 to 393 Bq kg(-1) dry weight. The total activity in sea water ranged from 15 to 88 Bq l(-1). Sediment samples obtained at deep sea locations more than 20 km offshore further revealed the presence of (137)Cs. The activity of (137)Cs varied from ND to 0.5 Bq kg(-1) dry weight, the activity increasing with offshore distance and depth. The activity concentrations presented herein should be considered useful in assessing the impact of any future radiological contamination to the marine environment.

Technical note: An improved approach to determining background aerosol concentrations with PILS sampling on aircraft

NASA Astrophysics Data System (ADS)

Fukami, Christine S.; Sullivan, Amy P.; Ryan Fulgham, S.; Murschell, Trey; Borch, Thomas; Smith, James N.; Farmer, Delphine K.

2016-07-01

Particle-into-Liquid Samplers (PILS) have become a standard aerosol collection technique, and are widely used in both ground and aircraft measurements in conjunction with off-line ion chromatography (IC) measurements. Accurate and precise background samples are essential to account for gas-phase components not efficiently removed and any interference in the instrument lines, collection vials or off-line analysis procedures. For aircraft sampling with PILS, backgrounds are typically taken with in-line filters to remove particles prior to sample collection once or twice per flight with more numerous backgrounds taken on the ground. Here, we use data collected during the Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ) to demonstrate that not only are multiple background filter samples are essential to attain a representative background, but that the chemical background signals do not follow the Gaussian statistics typically assumed. Instead, the background signals for all chemical components analyzed from 137 background samples (taken from ∼78 total sampling hours over 18 flights) follow a log-normal distribution, meaning that the typical approaches of averaging background samples and/or assuming a Gaussian distribution cause an over-estimation of background samples - and thus an underestimation of sample concentrations. Our approach of deriving backgrounds from the peak of the log-normal distribution results in detection limits of 0.25, 0.32, 3.9, 0.17, 0.75 and 0.57 μg m-3 for sub-micron aerosol nitrate (NO3-), nitrite (NO2-), ammonium (NH4+), sulfate (SO42-), potassium (K+) and calcium (Ca2+), respectively. The difference in backgrounds calculated from assuming a Gaussian distribution versus a log-normal distribution were most extreme for NH4+, resulting in a background that was 1.58× that determined from fitting a log-normal distribution.

Characterization of particle emission from laser printers.

PubMed

Scungio, Mauro; Vitanza, Tania; Stabile, Luca; Buonanno, Giorgio; Morawska, Lidia

2017-05-15

Emission of particles from laser printers in office environments is claimed to have impact on human health due to likelihood of exposure to high particle concentrations in such indoor environments. In the present paper, particle emission characteristics of 110 laser printers from different manufacturers were analyzed, and estimations of their emission rates were made on the basis of measurements of total concentrations of particles emitted by the printers placed in a chamber, as well as particle size distributions. The emission rates in terms of number, surface area and mass were found to be within the ranges from 3.39×10 8 partmin -1 to 1.61×10 12 partmin -1 , 1.06×10 0 mm 2 min -1 to 1.46×10 3 mm 2 min -1 and 1.32×10 -1 μgmin -1 to 1.23×10 2 μgmin -1 , respectively, while the median mode value of the emitted particles was found equal to 34nm. In addition, the effect of laser printing emissions in terms of employees' exposure in offices was evaluated on the basis of the emission rates, by calculating the daily surface area doses (as sum of alveolar and tracheobronchial deposition fraction) received assuming a typical printing scenario. In such typical printing conditions, a relatively low total surface area dose (2.7mm 2 ) was estimated for office employees with respect to other indoor microenvironments including both workplaces and homes. Nonetheless, for severe exposure conditions, characterized by operating parameters falling beyond the typical values (i.e. smaller office, lower ventilation, printer located on the desk, closer to the person, higher printing frequency etc.), significantly higher doses are expected. Copyright © 2017 Elsevier B.V. All rights reserved.

The cubicon method for concentrating membrane proteins in the cubic mesophase.

PubMed

Ma, Pikyee; Weichert, Dietmar; Aleksandrov, Luba A; Jensen, Timothy J; Riordan, John R; Liu, Xiangyu; Kobilka, Brian K; Caffrey, Martin

2017-09-01

The lipid cubic phase (in meso) method is an important approach for generating crystals and high-resolution X-ray structures of integral membrane proteins. However, as a consequence of instability, it can be impossible-using traditional methods-to concentrate certain membrane proteins and complexes to values suitable for in meso crystallization and structure determination. The cubicon method described here exploits the amphiphilic nature of membrane proteins and their natural tendency to partition preferentially into lipid bilayers from aqueous solution. Using several rounds of reconstitution, the protein concentration in the bilayer of the cubic mesophase can be ramped up stepwise from less than a milligram per milliliter to tens of milligrams per milliliter for crystallogenesis. The general applicability of the method is demonstrated with five integral membrane proteins: the β 2 -adrenergic G protein-coupled receptor (β 2 AR), the peptide transporter (PepT St ), diacylglycerol kinase (DgkA), the alginate transporter (AlgE) and the cystic fibrosis transmembrane conductance regulator (CFTR). In the cases of β 2 AR, PepT St , DgkA and AlgE, an effective 20- to 45-fold concentration was realized, resulting in a protein-laden mesophase that allowed the formation of crystals using the in meso method and structure determination to resolutions ranging from 2.4 Å to 3.2 Å. In addition to opening up in meso crystallization to a broader range of integral membrane protein targets, the cubicon method should find application in situations that require membrane protein reconstitution in a lipid bilayer at high concentrations. These applications include functional and biophysical characterization studies for ligand screening, drug delivery, antibody production and protein complex formation. A typical cubicon experiment can be completed in 3-5 h.

PET bottle use patterns and antimony migration into bottled water and soft drinks: the case of British and Nigerian bottles.

PubMed

Tukur, Aminu; Sharp, Liz; Stern, Ben; Tizaoui, Chedly; Benkreira, Hadj

2012-04-01

While antimony has been reported to migrate from PET bottles into contents, reports on bottled water and soft drinks usage and PET bottle reuse patterns are currently unavailable in the literature. Bottle use conditions and patterns are important determinants of antimony migration. In this work a survey assessing the pattern of bottle use and reuse in Britain and Nigeria was undertaken. The survey findings influenced the design of laboratory experiments that assessed the migration of antimony from PET bottles into water and soft drinks. Typical storage durations for bottled contents between purchase and opening for use were 7 days or less. However storage of up to one year was reported. Bottle reuse was high and similar for the two countries with reuse durations being higher in Nigeria. The antimony concentration in 32 PET bottle materials from Britain and Nigeria were similar and ranged between 177 and 310 mg kg(-1). For 47 freshly purchased British bottled contents antimony concentration ranged between 0.03 and 6.61 μg L(-1) with only one sample exceeding the EU acceptable limit. Concentrations of Cd, Ge, Zn, Al, Be, Ti, Co and Pb were also measured. At realistic temperatures of 40 and 60 °C antimony concentration in deionised water in bottles remained below the EU acceptable limit even after 48 h exposure. The limit was exceeded for most exposures at 80 °C. Concentration of antimony in some bottled contents exceeded the EU limit after 11 months of storage at room temperature. Bottle aging and increase in bottle volume were associated with decreased migration of antimony from bottles.

Identifying source regions for the atmospheric input of PCDD/Fs to the Baltic Sea

NASA Astrophysics Data System (ADS)

Sellström, Ulla; Egebäck, Anna-Lena; McLachlan, Michael S.

PCDD/F contamination of the Baltic Sea has resulted in the European Union imposing restrictions on the marketing of several fish species. Atmospheric deposition is the major source of PCDD/Fs to the Baltic Sea, and hence there is a need to identify the source regions of the PCDD/Fs in ambient air over the Baltic Sea. A novel monitoring strategy was employed to address this question. During the winter of 2006-2007 air samples were collected in Aspvreten (southern Sweden) and Pallas (northern Finland). Short sampling times (24 h) were employed and only samples with stable air mass back trajectories were selected for analysis of the 2,3,7,8-substituted PCDD/F congeners. The range in the PCDD/F concentrations from 40 samples collected at Aspvreten was a factor of almost 50 (range 0.6-29 fg TEQ/m 3). When the samples were grouped according to air mass origin into seven compass sectors, the variability was much lower (typically less than a factor of 3). This indicates that air mass origin was the primary source of the variability. The contribution of each sector to the PCDD/F contamination over the Baltic Sea during the winter half year of 2006/2007 was calculated from the average PCDD/F concentration for each sector and the frequency with which the air over the Baltic Sea came from that sector. Air masses originating from the south-southwest, south-southeast and east segments contributed 65% of the PCDDs and 75% of the PCDFs. Strong correlations were obtained between the concentrations of most of the PCDD/F congeners and the concentration of soot. These correlations can be used to predict the PCDD/F concentrations during the winter half year from inexpensive soot measurements.

Renal uptake and tolerability of a 2'-O-methoxyethyl modified antisense oligonucleotide (ISIS 113715) in monkey.

PubMed

Henry, Scott P; Johnson, Mark; Zanardi, Thomas A; Fey, Robert; Auyeung, Diana; Lappin, Patrick B; Levin, Arthur A

2012-11-15

The primary target organ for uptake of systemically administered phosphorothioate oligonucleotides is the kidney cortex and the proximal tubular epithelium in particular. To determine the effect of oligonucleotide uptake on renal function, a detailed renal physiology study was performed in cynomolgus monkeys treated with 10-40 mg/kg/week ISIS 113715 for 4 weeks. The concentrations of oligonucleotide in the kidney cortex ranged from 1400 to 2600 μg/g. These concentrations were associated with histologic changes in proximal tubular epithelial cells that ranged from the appearance of cytoplasmic basophilic granules to atrophic and degenerative changes at higher concentrations. However, there were no renal functional abnormalities as determined by the typical measurements of blood urea nitrogen, serum creatinine, creatinine clearance, or urine specific gravity. Nor were there changes in glomerular filtration rate, or renal blood flow. Specific urinary markers of tubular epithelial cell damage, such as N-acetyl-glucosaminidase, and α-glutathione-s-transferase were not affected. Tubular function was further evaluated by monitoring the urinary excretion of amino acids, β(2)-microglobulin, or glucose. Renal function was challenged by administering a glucose load and by examining concentrating ability after a 4-h water deprivation. Neither challenge produced any evidence of change in renal function. The only change observed was a low incidence of increased urine protein/creatinine ratio in monkeys treated with ≥40 mg/kg/week which was rapidly reversible. Collectively, these data indicate that ISIS 113715-uptake by the proximal tubular epithelium has little or no effect on renal function at concentrations of 2600 μg/g. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Functionality based detection of airborne engineered nanoparticles in quasi real time: a new type of detector and a new metric.

PubMed

Neubauer, Nicole; Seipenbusch, Martin; Kasper, Gerhard

2013-08-01

A new type of detector which we call the Catalytic Activity Aerosol Monitor (CAAM) was investigated towards its capability to detect traces of commonly used industrial catalysts in ambient air in quasi real time. Its metric is defined as the catalytic activity concentration (CAC) expressed per volume of sampled workplace air. We thus propose a new metric which expresses the presence of nanoparticles in terms of their functionality - in this case a functionality of potential relevance for damaging effects - rather than their number, surface, or mass concentration in workplace air. The CAAM samples a few micrograms of known or anticipated airborne catalyst material onto a filter first and then initiates a chemical reaction which is specific to that catalyst. The concentration of specific gases is recorded using an IR sensor, thereby giving the desired catalytic activity. Due to a miniaturization effort, the laboratory prototype is compact and portable. Sensitivity and linearity of the CAAM response were investigated with catalytically active palladium and nickel nano-aerosols of known mass concentration and precisely adjustable primary particle size in the range of 3-30 nm. With the miniature IR sensor, the smallest detectable particle mass was found to be in the range of a few micrograms, giving estimated sampling times on the order of minutes for workplace aerosol concentrations typically reported in the literature. Tests were also performed in the presence of inert background aerosols of SiO2, TiO2, and Al2O3. It was found that the active material is detectable via its catalytic activity even when the particles are attached to a non-active background aerosol.

[Spatial distribution and potential ecological risk assessment of heavy metals in sediments of Yalu River estuary wetland mudflat.

PubMed

Zhang, Chun Peng; Li, Fu Xiang

2016-09-01

Kriging interpolation analysis was conducted with ArcGIS to find out the distribution characteristics of heavy metals concentrations in the surface sediments of the coastal wetland mudflat on the Yalu River estuary, environmental risk index and Hakanson potential ecological risk index were used to assess their extents of pollution in this area.The concentrations of heavy metals in the surface sediments of the study area were at a relatively high level compared with the typical estuarine wetland. The concentration of heavy metals in the east was higher than that in the west, and in the human activity area, the concentration was higher. Cu was found to contribute the most to the pollution status based on environmental risk index method, while Hg and Cd produced the greatest potential ecological harm according to Hankanson Potential ecological risk index method. The average potential ecological risk index (RI) of the Yalu River estuary wetland was 189.30 (ranged from 93.65-507.20), suggesting a moderate ecological risk. However, the potential ecological risk was highest in the east and should be treated as the major heavy metal pollution prevention area in the future.

Estimating the Influence of Biological Ice Nuclei on Clouds with Regional Scale Simulations

NASA Astrophysics Data System (ADS)

Hummel, Matthias; Hoose, Corinna; Schaupp, Caroline; Möhler, Ottmar

2014-05-01

Cloud properties are largely influenced by the atmospheric formation of ice particles. Some primary biological aerosol particles (PBAP), e.g. certain bacteria, fungal spores or pollen, have been identified as effective ice nuclei (IN). The work presented here quantifies the IN concentrations originating from PBAP in order to estimate their influences on clouds with the regional scale atmospheric model COSMO-ART in a six day case study for Western Europe. The atmospheric particle distribution is calculated for three different PBAP (bacteria, fungal spores and birch pollen). The parameterizations for heterogeneous ice nucleation of PBAP are derived from AIDA cloud chamber experiments with Pseudomonas syringae bacteria and birch pollen (Schaupp, 2013) and from published data on Cladosporium spores (Iannone et al., 2011). A constant fraction of ice-active bacteria and fungal spores relative to the total bacteria and spore concentration had to be assumed. At cloud altitude, average simulated PBAP number concentrations are ~17 L-1 for bacteria and fungal spores and ~0.03 L-1 for birch pollen, including large temporal and spatial variations of more than one order of magnitude. Thus, the average, 'diagnostic' in-cloud PBAP IN concentrations, which only depend on the PBAP concentrations and temperature, without applying dynamics and cloud microphysics, lie at the lower end of the range of typically observed atmospheric IN concentrations . Average PBAP IN concentrations are between 10-6 L-1 and 10-4 L-1. Locally but not very frequently, PBAP IN concentrations can be as high as 0.2 L-1 at -10° C. Two simulations are compared to estimate the cloud impact of PBAP IN, both including mineral dust as an additional background IN with a constant concentration of 100 L-1. One of the simulations includes additional PBAP IN which can alter the cloud properties compared to the reference simulation without PBAP IN. The difference in ice particle and cloud droplet concentration between both simulations is a result of the heterogeneous ice nucleation of PBAP. In the chosen case setup, two effects can be identified which are occurring at different altitudes. Additional PBAP IN directly enhance the ice crystal concentration at lower parts of a mixed-phase cloud. This increase comes with a decrease in liquid droplet concentration in this part of a cloud. Therefore, a second effect takes place, where less ice crystals are formed by dust-driven heterogeneous as well as homogeneous ice nucleation in upper parts of a cloud, probably due to a lack of liquid water reaching these altitudes. Overall, diagnostic PBAP IN concentrations are very low compared to typical IN concentration, but reach maxima at temperatures where typical IN are not very ice-active. PBAP IN can therefore influence clouds to some extent. Iannone, R., Chernoff, D. I., Pringle, A., Martin, S. T., and Bertram, A. K.: The ice nucleation ability of one of the most abundant types of fungal spores found in the atmosphere, Atmos. Chem. Phys., 11, 1191-1201, 10.5194/acp-11-1191-2011, 2011. Schaupp, C.: Untersuchungen zur Rolle von Bakterien und Pollen als Wolkenkondensations- und Eiskeime in troposphärischen Wolken, Ph.D. thesis, Institute of Environmental Physics, Heidelberg University, Heidelberg, Germany, 2013.

Pharmacodynamic Evaluation of the Intracellular Activities of Antibiotics against Staphylococcus aureus in a Model of THP-1 Macrophages

PubMed Central

Barcia-Macay, Maritza; Seral, Cristina; Mingeot-Leclercq, Marie-Paule; Tulkens, Paul M.; Van Bambeke, Françoise

2006-01-01

The pharmacodynamic properties governing the activities of antibiotics against intracellular Staphylococcus aureus are still largely undetermined. Sixteen antibiotics of seven different pharmacological classes (azithromycin and telithromycin [macrolides]; gentamicin [an aminoglycoside]; linezolid [an oxazolidinone]; penicillin V, nafcillin, ampicillin, and oxacillin [β-lactams]; teicoplanin, vancomycin, and oritavancin [glycopeptides]; rifampin [an ansamycin]; and ciprofloxacin, levofloxacin, garenoxacin, and moxifloxacin [quinolones]) have been examined for their activities against S. aureus (ATCC 25923) in human THP-1 macrophages (intracellular) versus that in culture medium (extracellular) by using a 0- to 24-h exposure time and a wide range of extracellular concentrations (including the range of the MIC to the maximum concentration in serum [Cmax; total drug] of humans). All molecules except the macrolides caused a net reduction in bacterial counts that was time and concentration/MIC ratio dependent (four molecules tested in detail [gentamicin, oxacillin, moxifloxacin, and oritavancin] showed typical sigmoidal dose-response curves at 24 h). Maximal intracellular activities remained consistently lower than extracellular activities, irrespective of the level of drug accumulation and of the pharmacological class. Relative potencies (50% effective concentration or at a fixed extracellular concentration/MIC ratio) were also decreased, but to different extents. At an extracellular concentration corresponding to their Cmaxs (total drug) in humans, only oxacillin, levofloxacin, garenoxacin, moxifloxacin, and oritavancin had truly intracellular bactericidal effects (2-log decrease or more, as defined by the Clinical and Laboratory Standards Institute guidelines). The intracellular activities of antibiotics against S. aureus (i) are critically dependent upon their extracellular concentrations and the duration of cell exposure (within the 0- to 24-h time frame) to antibiotics and (ii) are always lower than those that can be observed extracellularly. This model may help in rationalizing the choice of antibiotic for the treatment of S. aureus intracellular infections. PMID:16495241

Gas-liquid equilibrium in a CO{sub 2}-MDEA-H{sub 2}O system and the effect of piperazine on it

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

Xu, G.W.; Zhang, C.F.; Qin, S.J.

1998-04-01

Aqueous N-methyldiethanolamine (MDEA) solutions are widely used for removal of the acid gas (H{sub 2}S and CO{sub 2}) from natural gas synthesis and refinery gas streams. Solubility data of CO{sub 2} and vapor pressure of water in 3.04--4.28 kmol/m{sup 3} aqueous N-methyldiethanolamine (MDEA) solutions were obtained at temperatures ranging from 40 to 100 C and CO{sub 2} partial pressures ranging from 0.876 to 1,013 kPa. A thermodynamic model was proposed and used for predicting CO{sub 2} solubility and water vapor pressure. An enthalpy change of absorption of CO{sub 2} in 4.28 kmol/m{sup 3} MDEA solution was estimated. The effect ofmore » piperazine (PZ) concentration on CO{sub 2} loading in MDEA solutions was determined at piperazine concentration ranging from 0 to 0.515 kmol/m{sup 3}. The results show that piperazine is beneficial to the CO{sub 2} loading. The equilibrium partial pressure of piperazine in the PZ-MDEA-H{sub 2}O system was measured in an Ellis Cell. Results show that the PZ-MDEA-H{sub 2}O system is a typical negative deviation system, with the strength of deviation decreasing with MDEA solutions.« less

Presence and distribution of wastewater-derived pharmaceuticals in soil irrigated with reclaimed water

USGS Publications Warehouse

Kinney, C.A.; Furlong, E.T.; Werner, S.L.; Cahill, J.D.

2006-01-01

Three sites in the Front Range of Colorado, USA, were monitored from May through September 2003 to assess the presence and distribution of pharmaceuticals in soil irrigated with reclaimed water derived from urban wastewater. Soil cores were collected monthly, and 19 pharmaceuticals, all of which were detected during the present study, were measured in 5-cm increments of the 30-cm cores. Samples of reclaimed water were analyzed three times during the study to assess the input of pharmaceuticals. Samples collected before the onset of irrigation in 2003 contained numerous pharmaceuticals, likely resulting from the previous year's irrigation. Several of the selected pharmaceuticals increased in total soil concentration at one or more of the sites. The four most commonly detected pharmaceuticals were erythromycin, carbamazepine, fluoxetine, and diphenhydramine. Typical concentrations of the individual pharmaceuticals observed were low (0.02-15 ??g/kg dry soil). The existence of subsurface maximum concentrations and detectable concentrations at the lowest sampled soil depth might indicate interactions of soil components with pharmaceuticals during leaching through the vadose zone. Nevertheless, the present study demonstrates that reclaimed-water irrigation results in soil pharmaceutical concentrations that vary through the irrigation season and that some compounds persist for months after irrigation. ?? 2006 SETAC.

Feasibility of atmospheric methane removal using methanotrophic biotrickling filters.

PubMed

Yoon, Sukhwan; Carey, Jeffrey N; Semrau, Jeremy D

2009-07-01

Methane is a potent greenhouse gas with a global warming potential ~23 times that of carbon dioxide. Here, we describe the modeling of a biotrickling filtration system composed of methane-consuming bacteria, i.e., methanotrophs, to assess the utility of these systems in removing methane from the atmosphere. Model results indicate that assuming the global average atmospheric concentration of methane, 1.7 ppmv, methane removal is ineffective using these methanotrophic biofilters as the methane concentration is too low to enable cell survival. If the concentration is increased to 500-6,000 ppmv, however, similar to that found above landfills and in concentrated animal feeding operations (factory farms), 4.98-35.7 tons of methane can be removed per biofilter per year assuming biotrickling filters of typical size (3.66 m in diameter and 11.5 m in height). Using reported ranges of capital, operational, and maintenance costs, the cost of the equivalent ton of CO(2) removal using these systems is $90-$910 ($2,070-$20,900 per ton of methane), depending on the influent concentration of methane and if heating is required. The use of methanotrophic biofilters for controlling methane emissions is technically feasible and, provided that either the costs of biofilter construction and operation are reduced or the value of CO(2) credits is increased, can also be economically attractive.

A novel portable filtration system for sampling and concentration of microorganisms: Demonstration on marine microalgae with subsequent quantification using IC-NASBA.

PubMed

Loukas, Christos-Moritz; Mowlem, Matthew C; Tsaloglou, Maria-Nefeli; Green, Nicolas G

2018-05-01

This paper presents a novel portable sample filtration/concentration system, designed for use on samples of microorganisms with very low cell concentrations and large volumes, such as water-borne parasites, pathogens associated with faecal matter, or toxic phytoplankton. The example application used for demonstration was the in-field collection and concentration of microalgae from seawater samples. This type of organism is responsible for Harmful Algal Blooms (HABs), an example of which is commonly referred to as "red tides", which are typically the result of rapid proliferation and high biomass accumulation of harmful microalgal species in the water column or at the sea surface. For instance, Karenia brevis red tides are the cause of aquatic organism mortality and persistent blooms may cause widespread die-offs of populations of other organisms including vertebrates. In order to respond to, and adequately manage HABs, monitoring of toxic microalgae is required and large-volume sample concentrators would be a useful tool for in situ monitoring of HABs. The filtering system presented in this work enables consistent sample collection and concentration from 1 L to 1 mL in five minutes, allowing for subsequent benchtop sample extraction and analysis using molecular methods such as NASBA and IC-NASBA. The microalga Tetraselmis suecica was successfully detected at concentrations ranging from 2 × 10 5  cells/L to 20 cells/L. Karenia brevis was also detected and quantified at concentrations between 10 cells/L and 10 6  cells/L. Further analysis showed that the filter system, which concentrates cells from very large volumes with consequently more reliable sampling, produced samples that were more consistent than the independent non-filtered samples (benchtop controls), with a logarithmic dependency on increasing cell numbers. This filtering system provides simple, rapid, and consistent sample collection and concentration for further analysis, and could be applied to a wide range of different samples and target organisms in situations lacking laboratories. Copyright © 2018. Published by Elsevier B.V.

Exchange of carbonyl sulfide (OCS) between soils and atmosphere under various CO2 concentrations

NASA Astrophysics Data System (ADS)

Bunk, Rüdiger; Behrendt, Thomas; Yi, Zhigang; Andreae, Meinrat O.; Kesselmeier, Jürgen

2017-06-01

A new continuous integrated cavity output spectroscopy analyzer and an automated soil chamber system were used to investigate the exchange processes of carbonyl sulfide (OCS) between soils and the atmosphere under laboratory conditions. The exchange patterns of OCS between soils and the atmosphere were found to be highly dependent on soil moisture and ambient CO2 concentration. With increasing soil moisture, OCS exchange ranged from emission under dry conditions to an uptake within an optimum moisture range, followed again by emission at high soil moisture. Elevated CO2 was found to have a significant impact on the exchange rate and direction as tested with several soils. There is a clear tendency toward a release of OCS at higher CO2 levels (up to 7600 ppm), which are typical for the upper few centimeters within soils. At high soil moisture, the release of OCS increased sharply. Measurements after chloroform vapor application show that there is a biotic component to the observed OCS exchange. Furthermore, soil treatment with the fungi inhibitor nystatin showed that fungi might be the dominant OCS consumers in the soils we examined. We discuss the influence of soil moisture and elevated CO2 on the OCS exchange as a change in the activity of microbial communities. Physical factors such as diffusivity that are governed by soil moisture also play a role. Comparing KM values of the enzymes to projected soil water CO2 concentrations showed that competitive inhibition is unlikely for carbonic anhydrase and PEPCO but might occur for RubisCO at higher CO2 concentrations.

Measurements of Gas-phase H2so4, Oh, So2 and Aerosol Size Distribution On Mount Zugspitze At The Schneefernerhaus: Estimation of Sources and Sinks of Sulfuric Acid

NASA Astrophysics Data System (ADS)

Uecker, J.; Hanke, M.; Kamm, S.; Umann, B.; Arnold, F.; Poeschl, U.; Niessner, R.

Gas-phase sulfuric acid and OH have been measured by the novel MPI-K ULTRA- CIMS (ultra-trace gas detection by CIMS technique) at the Schneefernerhaus( 2750 m asl; below the summit of Mount Zugspitze, Germany) in October 2001. These mea- surements were accompanied by measurements of SO2 with another MPI-K CIMS instrument and aerosol size distribution measurements by DMPS (differential mobil- ity particle sizer) operated by the Institut fuer Wasserchemie (Technische Universitaet Muenchen). In that way a data set was obtained which allows investigating major sources and sinks of sulfuric acid under relative clean conditions. H2SO4 and espe- cially OH concentrations are relatively well correlated to solar flux. Noon maximum concentrations of OH and H2SO4 of 6.5·106 and 2·106 cm-3, respectively, were ob- served. The average SO2 concentrations were below 20 ppt. The aerosol size distribu- tion was obtained in 39 size ranges from 10 to 1056 nm. Typical aerosol concentrations are in the range of 400 to 1800 cm-3 during the discussed period of time. An estima- tion of the production rate of H2SO4 was inferred building on the reaction of SO2 and OH, while the loss rate was calculated by considering the condensation of H2SO4 on aerosol particles (Fuchs and Sutugin approach). Results of the measurements and calculations will be discussed.

Transport and fate of chloride from road salt within a mixed urban and agricultural watershed in Illinois (USA): assessing the influence of chloride application rates

NASA Astrophysics Data System (ADS)

Ludwikowski, Jessica J.; Peterson, Eric W.

2018-06-01

In a typical winter season, approximately 471,000 tons of road salt are deposited along roadways in Illinois, USA. An estimated 45% of the deposited road salt will infiltrate through the soils and into shallow aquifers. Transported through shallow aquifers, chloride associated with the road salts has the potential to reside within groundwater for years based on the pathway, the geologic material, and the recharge rate of the aquifer system. Utilizing MODFLOW and MT3D, simulations employing various road-salt application rates were conducted to assess the net accumulation of chloride and the residence times of chloride in an agriculture-dominated watershed that originates in an urban area. A positive-linear relationship was observed between the application rate of chloride and both the maximum chloride concentration and total mass accumulated within the watershed. Simulated annual recharge rates along impacted surfaces ranged from 1,000 to 10,000 mg/L. After 60 years of application, simulated chloride concentrations in groundwater ranged from 197 to 1,900 mg/L. For all application rates, chloride concentrations within the groundwater rose at an annual rate of >3 mg/L. While concentrations increase throughout the system, the majority of chloride accumulation occurs near the roads and the urban areas. Model simulations reveal a positive relationship between application rate and residence time of chloride (1,123-1,288 days based on application rate). The models indicate that continued accumulation of chloride in shallow aquifers can be expected, and methods that apply less chloride effectively need to be examined.

Aircraft measurements of SO2, NOx, CO, and O3 over the coastal and offshore area of Yellow Sea of China.

PubMed

Yang, Xiaoyang; Wang, Xinhua; Yang, Wen; Xu, Jun; Ren, Lihong; He, Youjiang; Liu, Bing; Bai, Zhipeng; Meng, Fan; Hu, Min

2016-09-01

In order to investigate long-range transport of the air pollution in the East Asia, air pollutants, including SO2, NOx, CO, and O3, were observed by aircraft measurement over the coastal and offshore area of Yellow Sea of China in April 2011. NOx and SO2 seemed to become moderate in recent years, and the concentrations during the whole observations ranged from 0.49 to 9.57 ppb and from 0.10 to 16.02 ppb, respectively. The high concentrations of CO were measured with an average value of 0.98 ppm. The measured O3 average concentration was 76.25 ppb, which showed a higher level comparing with the results from some previous studies. Most of the results for the concentration values generally followed the typical characteristic of vertical and spatial distribution, which were "low altitude > high altitude" and "land/coastal > sea," respectively. Transport of polluted air mass from the continent to the aircraft measurement area was confirmed in some days during the observation by the meteorological analysis, while the measurement results supposed to represent the background level of the pollutants in rest days. Additionally, some small-scale air pollution plumes were observed. Significant positive correlations between NOx and SO2 indicated that these two species originated from the same region. On the other hand, good positive correlations between NOx and O3 found during 2-day flight suggested that the O3 formation was probably under "NOx-limited" regime in these days.

Biogeochemistry and nitrogen cycling in an Arctic, volcanic ecosystem

NASA Astrophysics Data System (ADS)

Fogel, M. L.; Benning, L.; Conrad, P. G.; Eigenbrode, J.; Starke, V.

2007-12-01

As part of a study on Mars Analogue environments, the biogeochemistry of Sverrefjellet Volcano, Bocfjorden, Svalbard, was conducted and compared to surrounding glacial, thermal spring, and sedimentary environments. An understanding of how nitrogen might be distributed in a landscape that had extinct or very cold adapted, slow- growing extant organisms should be useful for detecting unknown life forms. From high elevations (900 m) to the base of the volcano (sea level), soil and rock ammonium concentrations were uniformly low, typically less than 1- 3 micrograms per gm of rock or soil. In weathered volcanic soils, reduced nitrogen concentrations were higher, and oxidized nitrogen concentrations lower. The opposite was found in a weathered Devonian sedimentary soil. Plants and lichens growing on volcanic soils have an unusually wide range in N isotopic compositions from -5 to +12‰, a range rarely measured in temperate ecosystems. Nitrogen contents and isotopic compositions of volcanic soils and rocks were strongly influenced by the presence or absence of terrestrial herbivores or marine avifauna with higher concentrations of N and elevated N isotopic compositions occurring as patches in areas immediately influenced by reindeer, Arctic fox ( Alopex lagopus), and marine birds. Because of the extreme conditions in this area, ephemeral deposition of herbivore feces results in a direct and immediate N pulses into the ecosystem. The lateral extent and distribution of marine- derived nitrogen was measured on a landscape scale surrounding an active fox den. Nitrogen was tracked from the bones of marine birds to soil to vegetation. Because of extreme cold, slow biological rates and nitrogen cycling, a mosaic of N patterns develops on the landscape scale.

Transport and fate of chloride from road salt within a mixed urban and agricultural watershed in Illinois (USA): assessing the influence of chloride application rates

NASA Astrophysics Data System (ADS)

Ludwikowski, Jessica J.; Peterson, Eric W.

2018-01-01

In a typical winter season, approximately 471,000 tons of road salt are deposited along roadways in Illinois, USA. An estimated 45% of the deposited road salt will infiltrate through the soils and into shallow aquifers. Transported through shallow aquifers, chloride associated with the road salts has the potential to reside within groundwater for years based on the pathway, the geologic material, and the recharge rate of the aquifer system. Utilizing MODFLOW and MT3D, simulations employing various road-salt application rates were conducted to assess the net accumulation of chloride and the residence times of chloride in an agriculture-dominated watershed that originates in an urban area. A positive-linear relationship was observed between the application rate of chloride and both the maximum chloride concentration and total mass accumulated within the watershed. Simulated annual recharge rates along impacted surfaces ranged from 1,000 to 10,000 mg/L. After 60 years of application, simulated chloride concentrations in groundwater ranged from 197 to 1,900 mg/L. For all application rates, chloride concentrations within the groundwater rose at an annual rate of >3 mg/L. While concentrations increase throughout the system, the majority of chloride accumulation occurs near the roads and the urban areas. Model simulations reveal a positive relationship between application rate and residence time of chloride (1,123-1,288 days based on application rate). The models indicate that continued accumulation of chloride in shallow aquifers can be expected, and methods that apply less chloride effectively need to be examined.

The presence of radioactive materials in soil, sand and sediment samples of Potenga sea beach area, Chittagong, Bangladesh: Geological characteristics and environmental implication

NASA Astrophysics Data System (ADS)

Yasmin, Sabina; Barua, Bijoy Sonker; Uddin Khandaker, Mayeen; Kamal, Masud; Abdur Rashid, Md.; Abdul Sani, S. F.; Ahmed, H.; Nikouravan, Bijan; Bradley, D. A.

2018-03-01

Accurate quantification of naturally occurring radioactive materials in soil provides information on geological characteristics, possibility of petroleum and mineral exploration, radiation hazards to the dwelling populace etc. Of practical significance, the earth surface media (soil, sand and sediment) collected from the densely populated coastal area of Chittagong city, Bangladesh were analysed using a high purity germanium γ-ray spectrometer with low background radiation environment. The mean activities of 226Ra (238U), 232Th and 40K in the studied materials show higher values than the respective world average of 33, 36 and 474 Bq/kg reported by the UNSCEAR (2000). The deduced mass concentrations of the primordial radionuclides 238U, 232Th and 40K in the investigated samples are corresponding to the granite rocks, crustal minerals and typical rocks respectively. The estimated mean value of 232Th/238U for soil (3.98) and sediment (3.94) are in-line with the continental crustal average concentration of 3.82 for typical rock range reported by the National Council on Radiation Protection and Measurements (NCRP). But the tonalites and more silicic rocks elevate the mean value of 232Th/238U for sand samples amounting to 4.69. This indicates a significant fractionation during weathering or associated with the metasomatic activity in the investigated area of sand collection.

Radioactivity level in Chinese building ceramic tile.

PubMed

Xinwei, L

2004-01-01

The activity concentrations of (226)Ra, (232)Th and (40)K have been determined by gamma ray spectrometry. The concentrations of (226)Ra, (232)Th and (40)K range from 158.3 to 1087.6, 91.7 to 1218.4, and 473.8 to 1031.3 Bq kg(-1) for glaze, and from 63.5 to 131.4, 55.4 to 106.5, and 386.7 to 866.8 Bq kg(-1) for ceramic tile, respectively. The measured activity concentrations for these radionuclides were compared with the reported data of other countries and with the typical world values. The radium equivalent activities (Ra(eq)), external hazard index (H(ex)) and internal hazard index (H(in)) associated with the radionuclides were calculated. The Ra(eq) values of all ceramic tiles are lower than the limit of 370 Bq kg(-1). The values of H(ex) and H(in) calculated according to the Chinese criterion for ceramic tiles are less than unity. The Ra(eq) value for the glaze of glazed tile collected from some areas are >370 Bq kg(-1).

Acceptor and Excitation Density Dependence of the Ultrafast Polaron Absorption Signal in Donor-Acceptor Organic Solar Cell Blends.

PubMed

Zarrabi, Nasim; Burn, Paul L; Meredith, Paul; Shaw, Paul E

2016-07-21

Transient absorption spectroscopy on organic semiconductor blends for solar cells typically shows efficient charge generation within ∼100 fs, accounting for the majority of the charge carriers. In this Letter, we show using transient absorption spectroscopy on blends containing a broad range of acceptor content (0.01-50% by weight) that the rise of the polaron signal is dependent on the acceptor concentration. For low acceptor content (<10% by weight), the polaron signal rises gradually over ∼1 ps with most polarons generated after 200 fs, while for higher acceptor concentrations (>10%) most polarons are generated within 200 fs. The rise time in blends with low acceptor content was also found to be sensitive to the pump fluence, decreasing with increasing excitation density. These results indicate that the sub-100 fs rise of the polaron signal is a natural consequence of both the high acceptor concentrations in many donor-acceptor blends and the high excitation densities needed for transient absorption spectroscopy, which results in a short average distance between the exciton and the donor-acceptor interface.

The Role of Temporal Evolution in Modeling Atmospheric Emissions from Tropical Fires

NASA Technical Reports Server (NTRS)

Marlier, Miriam E.; Voulgarakis, Apostolos; Shindell, Drew T.; Faluvegi, Gregory S.; Henry, Candise L.; Randerson, James T.

2014-01-01

Fire emissions associated with tropical land use change and maintenance influence atmospheric composition, air quality, and climate. In this study, we explore the effects of representing fire emissions at daily versus monthly resolution in a global composition-climate model. We find that simulations of aerosols are impacted more by the temporal resolution of fire emissions than trace gases such as carbon monoxide or ozone. Daily-resolved datasets concentrate emissions from fire events over shorter time periods and allow them to more realistically interact with model meteorology, reducing how often emissions are concurrently released with precipitation events and in turn increasing peak aerosol concentrations. The magnitude of this effect varies across tropical ecosystem types, ranging from smaller changes in modeling the low intensity, frequent burning typical of savanna ecosystems to larger differences when modeling the short-term, intense fires that characterize deforestation events. The utility of modeling fire emissions at a daily resolution also depends on the application, such as modeling exceedances of particulate matter concentrations over air quality guidelines or simulating regional atmospheric heating patterns.

On Chip Protein Pre-Concentration for Enhancing the Sensitivity of Porous Silicon Biosensors.

PubMed

Arshavsky-Graham, Sofia; Massad-Ivanir, Naama; Paratore, Federico; Scheper, Thomas; Bercovici, Moran; Segal, Ester

2017-12-22

Porous silicon (PSi) nanomaterials have been widely studied as label-free optical biosensors for protein detection. However, these biosensors' performance, specifically in terms of their sensitivity (which is typically in the micromolar range), is insufficient for many applications. Herein, we present a proof-of-concept application of the electrokinetic isotachophoresis (ITP) technique for real-time preconcentration of a target protein on a PSi biosensor. With ITP, a highly concentrated target zone is delivered to the sensing area, where the protein target is captured by immobilized aptamers. The detection of the binding events is conducted in a label-free manner by reflective interferometric Fourier transformation spectroscopy (RIFTS). Up to 1000-fold enhancement in local concentration of the protein target and the biosensor's sensitivity are achieved, with a measured limit of detection of 7.5 nM. Furthermore, the assay is successfully performed in complex media, such as bacteria lysate samples, while the selectivity of the biosensor is retained. The presented assay could be further utilized for other protein targets, and to promote the development of clinically useful PSi biosensors.

AC/DC electrical conduction and dielectric properties of PMMA/PVAc/C60 down-shifting nanocomposite films

NASA Astrophysics Data System (ADS)

El-Bashir, S. M.; Alwadai, N. M.; AlZayed, N.

2018-02-01

Polymer nanocomposite films were prepared by doping fullerene C60 in polymer blend composed of polymethacrylate/polyvinyl acetate blends (PMMA/PVAc) using solution cast technique. The films were characterized by differential scanning calorimeter (DSC), Transmission electron microscope (TEM), DC/AC electrical conductivity and dielectric measurements in the frequency range (100 Hz- 1 MHz). The glass transition temperature, Tg, was increased by increasing the concentration of fullerene C60; this property reflects the increase of thermal stability by increasing the nanofiller content. The DC and AC electrical conductivities were enhanced by increasing C60 concentration due to the electron hopping or tunneling between filled and empty localized states above Tg. The relaxation time was determined from the αβ -relaxations and found to be attenuated by increasing the temperature as a typical behavior of amorphous polymers. The calculated values of thermodynamic parameters revealed the increase of molecular stability by increasing the doping concentration; this feature supports the application of PMMA/PVAc/C60 nanocomposite films in a wide scale of solar energy conversion applications such as luminescent down-shifting (LDS) coatings for photovoltaic cells.

Chemical characteristics of the major thermal springs of Montana

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

Mariner, R.H.; Presser, T.S.; Evans, W.C.

1976-07-01

Twenty-one thermal springs in western Montana were sampled for chemical, isotope, and gas compositions. Most of the springs issue dilute to slightly saline sodium-bicarbonate waters of neutral to slightly alkaline pH. A few of the springs issue sodium-mixed anion waters of near neutral pH. Fluoride concentrations are high in most of the thermal waters, up to 18 miligrams per litre, while F/Cl ratios range from 3/1 in the dilute waters to 1/10 in the slightly saline waters. Most of the springs are theoretically in thermodynamic equilibrium with respect to calcite and fluorite. Nitrogen is the major gas escaping from mostmore » of the hot springs; however, Hunters Hot Springs issue principally methane. The deuterium content of the hot spring waters is typical of meteoric water in western Montana. Geothermal calculations based on silica concentrations and Na-K-Ca ratios indicate that most of the springs are associated with low temperature aquifers (less than 100/sup 0/C). Chalcedony may be controlling the silica concentrations in these low temperature aquifers even in ''granitic'' terranes.« less

Petrology, mineralogy and geochemistry of mined coals, western Venezuela

USGS Publications Warehouse

Hackley, Paul C.; Warwick, Peter D.; González, Eligio

2005-01-01

Upper Paleocene to middle Miocene coal samples collected from active mines in the western Venezuelan States of Táchira, Mérida and Zulia have been characterized through an integrated geochemical, mineralogical and petrographic investigation. Proximate, ultimate, calorific and forms of sulfur values, major and trace element, vitrinite reflectance, maceral concentrations and mineral matter content have been determined for 16 channel samples from 14 mines. Ash yield generally is low, ranging from < 1 to 17 wt.% (mean = 5 wt.%) on a dry basis (db). Total sulfur content is low to moderate, ranging from 1 to 6 wt.%, db (average = 1.7 wt.%). Calorific value ranges from 25.21 to 37.21 MJ/kg (10,840–16,000 Btu/lb) on a moist, mineral-matter-free basis (average = 33.25 MJ/kg, 14,300 Btu/lb), placing most of the coal samples in the apparent rank classification of high-volatile bituminous. Most of the coal samples exhibit favorable characteristics on the various indices developed to predict combustion and coking behavior and concentrations of possible environmentally sensitive elements (As, Be, Cd, Cr, Co, Hg, Mn, Ni, Pb, Sb, Se, Th and U) generally are similar to the concentrations of these elements in most coals of the world, with one or two exceptions. Concentrations of the liptinite maceral group range from < 1% to 70 vol.%. Five samples contain > 20 vol.% liptinite, dominated by the macerals bituminite and sporinite. Collotelinite dominates the vitrinite group; telinite was observed in quantities of ≤ 1 vol.% despite efforts to better quantify this maceral by etching the sample pellets in potassium permanganate and also by exposure in an oxygen plasma chamber. Inertinite group macerals typically represent < 10 vol.% of the coal samples and the highest concentrations of inertinite macerals are found in distantly spaced (> 400 km) upper Paleocene coal samples from opposite sides of Lago de Maracaibo, possibly indicating tectonic controls on subsidence related to construction of the Andean orogen. Values of maximum reflectance of vitrinite in oil (Ro max) range between 0.42% and 0.85% and generally are consistent with the high-volatile bituminous rank classification obtained through ASTM methods. X-ray diffraction analyses of low-temperature ash residues indicate that kaolinite, quartz, illite and pyrite dominate the inorganic fraction of most samples; plagioclase, potassium feldspar, calcite, siderite, ankerite, marcasite, rutile, anatase and apatite are present in minor or trace concentrations. Semiquantitative values of volume percent pyrite content show a strong correlation with pyritic sulfur and some sulfide-hosted trace element concentrations (As and Hg). This work provides a modern quality dataset for the western Venezuela coal deposits currently being exploited and will serve as the foundation for an ongoing coal quality research program in Venezuela.

Rectified directional sensing in long-range cell migration

PubMed Central

Nakajima, Akihiko; Ishihara, Shuji; Imoto, Daisuke; Sawai, Satoshi

2014-01-01

How spatial and temporal information are integrated to determine the direction of cell migration remains poorly understood. Here, by precise microfluidics emulation of dynamic chemoattractant waves, we demonstrate that, in Dictyostelium, directional movement as well as activation of small guanosine triphosphatase Ras at the leading edge is suppressed when the chemoattractant concentration is decreasing over time. This ‘rectification’ of directional sensing occurs only at an intermediate range of wave speed and does not require phosphoinositide-3-kinase or F-actin. From modelling analysis, we show that rectification arises naturally in a single-layered incoherent feedforward circuit with zero-order ultrasensitivity. The required stimulus time-window predicts ~5 s transient for directional sensing response close to Ras activation and inhibitor diffusion typical for protein in the cytosol. We suggest that the ability of Dictyostelium cells to move only in the wavefront is closely associated with rectification of adaptive response combined with local activation and global inhibition. PMID:25373620

Measurements of mercury in the near-surface layer of the atmosphere of the Russian Arctic.

PubMed

Golubeva, N; Burtseva, L; Matishov, G

2003-05-01

A series of measurements of gaseous elemental mercury concentrations in near-surface air of the Russian Arctic Region were carried out from 1994 to 1997. The measurements were conducted in Murmansk at a stationary site in April-May 1994, on a cruise in Motovsky Bay and Kola Bay during May-June 1996, and along the Russian Northern Sea Route in April-May 1997 on board the nuclear icebreaker 'Soviet Union'. Silver absorption was used for trapping of mercury and the mass of mercury was determined by cold vapour atomic absorption spectrophotometery. Detection limits were approximately 0.3 ng/m(3) (+/- error 46%). Sixty samples were selected and analysed. Sample volumes were 2.2 m(3) ashore, and up to 6.6 m(3) over water. The meteorological conditions, including a wind speed and direction, during the sampling period were typical of the spring-summer period of year, and therefore the concentrations of atmospheric mercury are regarded as representative for this season. The mean concentrations of mercury ranged from 2.2 ng/m(3) for Murmansk city, 1.7 ng/m(3) for Kola Bay, 1.6 ng/m(3) for Motovsky Bay, 1.1 ng/m(3) for the eastern part of the Barents Sea and 0.7 ng/m(3) for the western part of the Kara Sea. The levels of mercury in Murmansk, and over Kola and Motovsky Bays were associated with a primary direction of a near-surface wind from the nearest sources of mercury emission located in the Russian North region. These are the non-ferrous metallurgical plants in Nickel in the case of Motovsky Bay and Murmansk garbage-disposal plant, for sampling points in Murmansk and over Kola Bay. These concentrations of mercury, measured in the spring-summer season, in near-surface air of the Russian North, are more than two-fold lower than the concentrations that are typical of continental background regions in western Russia, and are comparable to the concentrations measured in the Arctic regions of other countries.

Iron isotope constraints on arsenic release from Mekong Delta sediments, Cambodia

NASA Astrophysics Data System (ADS)

Matsumoto, T.; Yamaguchi, K. E.; Hirata, T.; Yamagata, Y.; Yamaguchi, A.; Abe, G.

2017-12-01

Arsenic-contaminated groundwater is a world-wide environmental problem and threatens more than 100 million people living in delta areas of South, SE and East Asia. It is typically associated with reducing aquifers with organic-rich alluvial sediments, little thermal gradients, low sulfate concentrations, and slow flushing rates. Such conditions are typical for low-lying countries in Asian deltas; however, compared to Bangladesh, Cambodia has received far less attention. Upon reductive dissolution of Fe-(oxyhydr)oxides that adsorbed As, Fe and As are released into solution as dissolved Fe2+ and arsenate, respectively. Following the oxidation of dissolved Fe2+, newly-formed Fe-(oxyhydr)oxides adsorb As again. Thus, in anoxic waters, concentrations of As correlate with those of dissolved Fe2+. Fluctuating redox conditions in the aquifer are control As release, although inhibition of adsorption of arsenate and arsenite onto the Fe-(oxyhydr)oxides occurs when the concentrations of phosphate, bicarbonate, silicate, and/or organic matter become sufficiently high. Biogeochemical redox reactions of Fe result in significant isotope fractionation (e.g., Johnson et al., 2008). We hypothesized that magnitude of isotope fractionation of Fe in the aquifer sediments, reflecting repeated (incomplete) redox reactions of Fe, may be proportional to the amount of total As release. We aim to calibrate the As release from aquifer sediment by Fe isotope analysis. As a preliminary study, series of sediment samples were collected from the Mekong Delta, Cambodia, in September 2016. Based on measurements by XRF, ICP-AES and ICP-MS, concentrations of As varied significantly covering the range from 4.5 to 15.5 µg/g with a median value of 11 µg/g (higher than the average crustal value of 5 µg/g), and those of Fe is from 2.6 to 9.7 wt.% with a median value of 7.1 wt.%. Concentrations of As and Fe show positive correlation (R2 = 0.72), indicating an effective redox cycling of Fe and As as stated above. Sediment incubation experiment to explore various pathways of As release would show time-series correlated changes in the Fe isotope compositions and As concentrations. The data obtained here are essential in investigating the mechanism of As release.

From single chemicals to mixtures--reproductive effects of levonorgestrel and ethinylestradiol on the fathead minnow.

PubMed

Runnalls, Tamsin J; Beresford, Nicola; Kugathas, Subramaniam; Margiotta-Casaluci, Luigi; Scholze, Martin; Scott, Alexander P; Sumpter, John P

2015-12-01

The aquatic environment is polluted with thousands of chemicals. It is currently unclear which of these pose a significant threat to aquatic biota. The typical exposure scenario is now represented by a widespread blanket of contamination composed of myriads of individual pollutants-each typically present at a low concentration. The synthetic steroids, 17α-ethinylestradiol and levonorgestrel, have been widely reported to be present in the aquatic environment in the low ng to sub-ng/l range. They are widely used in contraceptive formulations, both individually and in combination. Our research employed the fathead minnow (Pimephales promelas) 21 day 'pair-breeding' assay to assess reproductive output when pairs of fish were exposed to the single chemicals at low environmentally relevant concentrations, and then to a binary mixture of them. A variety of endpoints were assessed, including egg production, which was inhibited in a concentration-dependent manner by both the individual chemicals and the mixture. Significant, sex specific effects were also seen with both chemicals, at differing levels of biological organisation. Plasma concentrations of EE2 and levonorgestrel were predicted and in the case of levonorgestrel measured, and compared with the human therapeutic plasma concentrations (Read-Across approach) to support the interpretation of the results. A novel quantitative method was developed for the data analysis, which ensured a suitable endpoint for the comparative mixture assessment. This approach compares the reproductive performance from individual pairs of fish during chemical exposure to its pre-treatment performance. The responses from the empirical mixture study were compared to predictions derived from the single substance data. We hypothesised combined responses which were best described by the concept of concentration addition, and found no clear indications against this additivity expectation. However, the effect profiles support the current knowledge that both compounds act in different ways to reduce egg production in fish, and suggest that probably response addition (also called Independent action) is the more appropriate mixture model in this case. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Factors influencing variability in the infiltration of PM2.5 mass and its components

NASA Astrophysics Data System (ADS)

MacNeill, M.; Wallace, L.; Kearney, J.; Allen, R. W.; Van Ryswyk, K.; Judek, S.; Xu, X.; Wheeler, A.

2012-12-01

The infiltration of particles into homes can vary seasonally, between homes in a community and between communities. However, few studies have examined the day to day variability across multiple homes. We used continuous data collected from a 2-year (2005-2006) personal exposure study conducted in Windsor, ON to estimate daily infiltration factors (Finf) for fine particulate matter (PM2.5), Black Carbon (BC), and ultrafine particles (UFP) as well as the ambient personal exposure factor (Fpex) for PM2.5. In addition, the daily ambient and non-ambient generated components of indoor and personal concentrations were estimated. Median daily Finf estimates ranged from 0.26 to 0.36 across seasons for PM2.5; from 0.28 to 0.59 for BC; and from 0.15 to 0.26 for UFP. Median daily Fpex estimates ranged from 0.24 to 0.31 across seasons. Daily PM2.5 and UFP Finf and Fpex estimates were higher in summer than winter, although BC showed the opposite trend. Predictors of daily infiltration were typically related to window-opening behaviours, air conditioning, meteorological variables, and home age. In addition, use of electrostatic precipitators and stand alone air cleaners was associated with significantly reduced infiltration factors, indicating that these devices may provide a cost effective mechanism of reducing human exposures to particles of ambient origin. The majority of indoor PM2.5 (median 57-73%) and indoor BC (median 90-100%) was of ambient origin across seasons, while both personal PM2.5 and indoor UFPs had significant non-ambient contributions (median 60-65%). Factors that were found to increase non-ambient particle concentrations were typically related to cooking, candle use, supplemental heating, cleaning, and number of people in the home. Factors that were found to decrease non-ambient particle concentrations were open windows, and air cleaner use. This work has several implications to both epidemiologic studies and risk management. A better understanding of the factors influencing Finf and Fpex can improve exposure assessment and contribute to reduced exposure misclassification in epidemiologic studies. Furthermore, by increasing our knowledge of non-ambient and ambient exposures, risk associated with PM exposure can be managed more effectively.

Inter- and intra-individual variation in urinary biomarker concentrations over a 6-day sampling period. Part 1: metals.

PubMed

Smolders, Roel; Koch, Holger M; Moos, Rebecca K; Cocker, John; Jones, Kate; Warren, Nick; Levy, Len; Bevan, Ruth; Hays, Sean M; Aylward, Lesa L

2014-12-01

The aim of the current HBM-study is to further the understanding of the impact of inter- and intra-individual variability in HBM surveys as it may have implications for the design and interpretation of the study outcomes. As spot samples only provide a snapshot in time of the concentrations of chemicals in an individual, it remains unclear to what extent intra-individual variability plays a role in the overall variability of population-wide HBM surveys. The current paper describes the results of an intensive biomonitoring study, in which all individual urine samples of 8 individuals were collected over a 6-day sampling period (a total of 352 unique samples). By analyzing different metals (As, Cd, Mn, Ni) in each individual sample, inter- and intra-individual variability for these four metals could be determined, and the relationships between exposure, internal dose, and sampling protocol assessed. Although the range of biomarker values for different metals was well within the normal range reported in large-scale population surveys, large intra-individual differences over a 6-day period could also be observed. Typically, measured biomarker values span at least an order of magnitude within an individual, and more if specific exposure episodes could be identified. Fish consumption for example caused a twenty- to thirty-fold increase in urinary As-levels over a period of 2-6h. Intra-class correlation coefficients (ICC) were typically low for uncorrected biomarker values (between 0.104 and 0.460 for the 4 metals), but improved when corrected for creatinine or specific gravity (SG). The results show that even though urine is a preferred matrix for HBM studies, there are certain methodological issues that need to be taken into account in the interpretation of urinary biomarker data, related to the intrinsic variability of the urination process itself, the relationship between exposure events and biomarker quantification, and the timing of sampling. When setting up HBM-projects, this expected relationship between individual exposure episode and urinary biomarker concentration needs to be taken into account. Copyright © 2014. Published by Elsevier Ireland Ltd.

[Characteristic of Mercury Emissions and Mass Balance of the Typical Iron and Steel Industry].

PubMed

Zhang, Ya-hui; Zhang, Cheng; Wang, Ding-yong; Luo, Cheng-zhong; Yang, Xi; Xu, Feng

2015-12-01

To preliminarily discuss the mercury emission characteristics and its mass balance in each process of the iron and steel production, a typical iron and steel enterprise was chosen to study the total mercury in all employed materials and estimate the input and output of mercury during the steel production process. The results showed that the mercury concentrations of input materials in each technology ranged 2.93-159.11 µg · kg⁻¹ with the highest level observed in ore used in blast furnace, followed by coal of sintering and blast furnace. The mercury concentrations of output materials ranged 3.09-18.13 µg · kg⁻¹ and the mercury concentration of dust was the highest, followed by converter slag. The mercury input and the output in the coking plant were 1346.74 g · d⁻¹ ± 36.95 g · d⁻¹ and 177.42 g · d⁻¹ ± 13.73 g · d⁻¹, respectively. In coking process, mercury mainly came from the burning of coking coal. The sintering process was the biggest contributor for mercury input during the iron and steel production with the mercury input of 1075. 27 g · d⁻¹ ± 60.89 g · d⁻¹ accounting for 68.06% of the total mercury input during this production process, and the ore powder was considered as the main mercury source. For the solid output material, the output in the sintering process was 14.15 g · d⁻¹ ± 0.38 g · d⁻¹, accounting for 22.61% of the total solid output. The mercury emission amount from this studied iron and steel enterprise was estimated to be 553.83 kg in 2013 with the emission factor of 0.092 g · t⁻¹ steel production. Thus, to control the mercury emissions, iron and steel enterprises should combine with production practice, further reduce energy consumption of coking and sintering, or improve the quality of raw materials and reduce the input of mercury.

Estimating Ground-Level Particulate Matter (PM) Concentration using Satellite-derived Aerosol Optical Depth (AOD)

NASA Astrophysics Data System (ADS)

Park, Seohui; Im, Jungho

2017-04-01

Atmospheric aerosols are strongly associated with adverse human health effects. In particular, particulate matter less than 10 micrometers and 2.5 micrometers (i.e., PM10 and PM2.5, respectively) can cause cardiovascular and lung diseases such as asthma and chronic obstructive pulmonary disease (COPD). Air quality including PM has typically been monitored using station-based in-situ measurements over the world. However, in situ measurements do not provide spatial continuity over large areas. An alternative approach is to use satellite remote sensing as it provides data over vast areas at high temporal resolution. The literature shows that PM concentrations are related with Aerosol Optical Depth (AOD) that is derived from satellite observations, but it is still difficult to identify PM concentrations directly from AOD. Some studies used statistical approaches for estimating PM concentrations from AOD while some others combined numerical models and satellite-derived AOD. In this study, satellite-derived products were used to estimate ground PM concentrations based on machine learning over South Korea. Satellite-derived products include AOD from Geostationary Ocean Color Imager (GOCI), precipitation from Tropical Rainfall Measuring Mission (TRMM), soil moisture from AMSR-2, elevation from Shuttle Radar Topography Mission (SRTM), and land cover, land surface temperature and normalized difference vegetation index (NDVI) from Moderate Resolution Imaging Spectroradiometer (MODIS). PM concentrations data were collected from 318 stations. A statistical ordinary least squares (OLS) approach was also tested and compared with the machine learning approach (i.e., random forest). PM concentration was estimated during spring season (from March to May) in 2015 that typically shows high concentration of PM. The randomly selected 80% of data were used for model calibration and the remaining 20% were used for validation. The developed models were further tested for prediction of PM concentration. Results show that the estimation of PM10 was better than that of PM2.5 for both approaches. The performance of machine learning random forest was better (R2=0.53 and RMSE=17.74µm/m3 for PM10; R2=0.36 and RMSE=26.17 µm/m3 for PM2.5) than the statistical OLS approach (R2=0.13 and RMSE=23.66µm/m3 for PM10; R2=0.09 and RMSE=27.74 µm/m3 for PM2.5). However, both approaches did not fully model the entire dynamic range of PM concentrations, especially for very high concentrations, resulting in moderate underestimation.

Distribution and Source of Polycyclic Aromatic Hydrocarbons (PAHs) in Water Dissolved Phase, Suspended Particulate Matter and Sediment from Weihe River in Northwest China

PubMed Central

Chen, Yuyun; Jia, Rui; Yang, Shengke

2015-01-01

Weihe River is a typical river located in the arid and semi-arid regions of Northwest China. In this study, the distribution and sources of 16 polycyclic aromatic hydrocarbons (PAHs) in Weihe River were investigated. The concentrations of ∑PAHs ranged from 351 to 4427 ng/L with a mean value of 835.4 ng/L in water dissolved phase (WDP), from 3557 ng/L to 147,907 ng/L with a mean value of 20,780 ng /L in suspended particulate matter (SPM), and from 362 to 15,667 ng/g dry weight (dw) with a mean value of 2000 ng/g dw in sediment, respectively. The concentrations of PAHs in Weihe River were higher compared with other rivers in the world. In both WDP and sediment, the highest concentrations of ∑PAHs were observed in the middle reach, while the lowest concentrations of ∑PAHs were found in the lower reach. For SPM, however, the PAHs concentrations in the lower reach were highest and the PAHs concentrations in the upper reach were lowest. The ratios of anthracene/(anthracene + phenanthrene) and fluoranthene/(fluoranthene + pyrene) reflected a pattern of both pyrolytic and petrogenic input of PAHs in Weihe River. The potential ecosystem risk assessment indicated that harmful biological impairments occur frequently in Weihe River. PMID:26561824

Nutrient loadings to streams of the continental United States from municipal and industrial effluent?

USGS Publications Warehouse

Maupin, Molly A.; Ivahnenko, Tamara

2011-01-01

Data from the United States Environmental Protection Agency Permit Compliance System national database were used to calculate annual total nitrogen (TN) and total phosphorus (TP) loads to surface waters from municipal and industrial facilities in six major regions of the United States for 1992, 1997, and 2002. Concentration and effluent flow data were examined for approximately 118,250 facilities in 45 states and the District of Columbia. Inconsistent and incomplete discharge locations, effluent flows, and effluent nutrient concentrations limited the use of these data for calculating nutrient loads. More concentrations were reported for major facilities, those discharging more than 1 million gallons per day, than for minor facilities, and more concentrations were reported for TP than for TN. Analytical methods to check and improve the quality of the Permit Compliance System data were used. Annual loads were calculated using "typical pollutant concentrations" to supplement missing concentrations based on the type and size of facilities. Annual nutrient loads for over 26,600 facilities were calculated for at least one of the three years. Sewage systems represented 74% of all TN loads and 58% of all TP loads. This work represents an initial set of data to develop a comprehensive and consistent national database of point-source nutrient loads. These loads can be used to inform a wide range of water-quality management, watershed modeling, and research efforts at multiple scales.

An extended baseline examination of indoor VOCs in a city of low ambient pollution: Perth, Western Australia

NASA Astrophysics Data System (ADS)

Maisey, S. J.; Saunders, S. M.; West, N.; Franklin, P. J.

2013-12-01

This study of indoor air quality reports VOC concentrations in 386 suburban homes located in Perth Western Australia, a city of low ambient pollution and temperate climate. Details of indoor VOC concentrations, temperature, relative humidity, and information on house characteristics and occupant activities were collected during the sampling periods. The concentration of VOCs observed in typical homes was low and individual compounds rarely exceeded 5 μg m-3. Median individual VOC concentrations ranged from 0.06 μg m-3 for 1,1,1 trichloroethane and butyl ether to 26.6 μg m-3 for cis/trans 2-butene. Recently renovated homes had higher concentrations of VOCs than non renovated homes, including ∑VOCs (p = 0.026), ∑BTEX (p = 0.03), ∑xylene (p = 0.013), toluene (p = 0.05), cyclohexane (p = 0.039), and propyl benzene (p = 0.039). Statistical analyses showed house age and attached garages were not significant factors for any of the VOCs tested. The concentrations of indoor VOCs in Perth were lower than overseas observations and those reported in recent Australian studies, with inferences made to differences in the climate and the occupant behaviour. The results are a baseline profile of indoor VOCs over the period 2006-2011, in an Australian city of low population density and of generally low ambient pollution.

Interactions of trace metals with hydrogels and filter membranes used in DET and DGT techniques.

PubMed

Garmo, Oyvind A; Davison, William; Zhang, Hao

2008-08-01

Equilibrium partitioning of trace metals between bulk solution and hydrogels/filter was studied. Under some conditions, trace metal concentrations were higher in the hydrogels or filter membranes compared to bulk solution (enrichment). In synthetic soft water, enrichment of cationic trace metals in polyacrylamide hydrogels decreased with increasing trace metal concentration. Enrichment was little affected by Ca and Mg in the concentration range typically encountered in natural freshwaters, indicating high affinity but low capacity binding of trace metals to solid structure in polyacrylamide gels. The apparent binding strength decreased in the sequence: Cu > Pb > Ni approximately to Cd approximately to Co and a low concentration of cationic Cu eliminated enrichment of weakly binding trace metal cations. The polyacrylamide gels also had an affinity for fulvic acid and/or its trace metal complexes. Enrichment of cationic Cd in agarose gel and hydrophilic polyethersulfone filter was independent of concentration (10 nM to 5 microM) but decreased with increasing Ca/ Mg concentration and ionic strength, suggesting that it is mainly due to electrostatic interactions. However, Cu and Pb were enriched even after equilibration in seawater, indicating that these metals additionally bind to sites within the agarose gel and filter. Compared to the polyacrylamide gels, agarose gel had a lower affinity for metal-fulvic complexes. Potential biases in measurements made with the diffusive equilibration in thin-films (DET) technique, identified by this work, are discussed.

Characterization of water quality and biological communities, Fish Creek, Teton County, Wyoming, 2007-08

USGS Publications Warehouse

Eddy-Miller, Cheryl A.; Peterson, David A.; Wheeler, Jerrod D.; Leemon, Daniel J.

2010-01-01

Fish Creek, a tributary to the Snake River, is about 25 river kilometers long and is located in Teton County in western Wyoming near the town of Wilson. Public concern about nuisance growths of aquatic plants in Fish Creek have been increasing in recent years. To address this concern, the U.S. Geological Survey conducted a study in cooperation with the Teton Conservation District to characterize the water quality and biological communities in Fish Creek. Water-quality samples were collected for analyses of physical properties and water chemistry (nutrients, nitrate isotopes, and wastewater chemicals) between March 2007 and October 2008 from seven surface-water sites and three groundwater wells. During this same period, aquatic plant and macroinvertebrate samples were collected and habitat characteristics were measured at the surface-water sites. The main objectives of this study were to (1) evaluate nutrient concentrations (that influence biological indicators of eutrophication) and potential sources of nutrients by using stable isotope analysis and other indicator chemicals (such as caffeine and disinfectants) that could provide evidence of anthropogenic sources, such as wastewater or septic tank contamination in Fish Creek and adjacent groundwater, and (2) characterize the algal, macrophyte, and macroinvertebrate communities and habitat of Fish Creek. Nitrate was the dominant species of dissolved nitrogen present in all samples and was the only bioavailable species detected at concentrations greater than the laboratory reporting level in all surface-water samples. Average concentrations of dissolved nitrate in surface water were largest in samples collected from the two sites with seasonal flow near Teton Village and decreased downstream; the smallest concentration was at downstream site A-Wck. Concentrations of dissolved nitrate in groundwater were consistently greater than concentrations in corresponding surface-water sites during the same sampling event. Orthophosphate was the primary dissolved species of phosphorus present in all surface-water and groundwater samples. The average concentration of dissolved orthophosphate in surface water was largest in samples collected from near Teton Village; samples from all other sites had similar average concentrations. Concentrations of dissolved orthophosphate in groundwater also were typically greater than concentrations in corresponding surface-water sites during the same sampling event. The aquatic plant communities in Fish Creek typically were composed of a mixture of macrophytes, macroalgae, microalgae, and moss. The composition of the aquatic plant community in Fish Creek appeared to shift in the downstream direction in 2007. On average, the proportion of macrophytes ranged from about 1 percent at site A-R1U, the most upstream site, to 54 percent of the plant community at site A-R6D, the farthest downstream site sampled during 2007. The downstream increase in macrophytes was accompanied by a downstream decrease in microalgae. The average proportion of microalgae ranged from 80 percent at site A-R1U to 24 percent at site A-R6D. The proportion of the macroalgae Cladophora in the aquatic plant community was relatively high at sites A-Wck and A-R3D in both 2007 and 2008.

Sulfur concentration and isotopic variation in apatites from granitic to granodioritic plutons of a Cretaceous Cordilleran Batholith

NASA Astrophysics Data System (ADS)

Economos, R. C.

2012-12-01

Apatite is a common igneous accessory mineral with a high saturation temperature which can therefore crystallize over a significant portion of magmatic compositional space. Sulfur presents an opportunity to identify zoning in apatites. Unlike other trace elements, sulfur is relatively immobile in the apatite crystal structure and can be present in typical concentrations up to 1500 - 2000 ppm (or 0.5 to 1 wt% SO3). Sulfur concentration zoning in igneous apatites from ore producing magmatic systems has been identified (Streck and Dilles, 1998), but the interpretation of the cause of this zoning remains an open question. δ34S isotopic ratios of whole apatites have been used to track isotopic evolution associated with changes in magma fO2 and eruptive degassing (Rye, 2005). The presented work combines sulfur concentration mapping in zoned apatite crystals with in-situ SIMS 34S and 32S isotope measurements. Apatites were extracted from granite to granodiorite samples from the Cadiz Valley Batholith in the central Mojave Desert. This batholith is related to the pulse of Cretaceous Cordilleran magmatism that generated large batholiths in the Sierra Nevada and the Penninsular Ranges. The Mojave segment of the Cretaceous arc is unique in their construction into a full thickness of continental crust which exerted a strong influence on magmatic compositions. Apatite grains were mounted parallel to C axes, ground until grains were approximately bisected, and analyzed by Electron Microprobe at UCLA, for CaO, P2O5, SO3 and SiO2. Grains were surveyed and those yielding anomalous SO3 contents were investigated by micron-scale concentration mapping. Typical SO3 concentrations of apatites from all samples were ~0.2 wt%, while 8 to 10% of apatite grains from two samples contained cores with concentrations ranging up to 0.5 wt%. The sulfur zoning in these samples is oscillatory, in some grains representing 5 to 6 repetitions of high and low concentrations. Based on these textures, our initial interpretation is that this zoning is magmatic. Ratios of 32S to 34S in these grains were analyzed by Secondary Ionization Mass Spectrometry at UCLA in multi-collector mode utilizing a Cs+ primary ion beam and two electron multiplier ion counters. Although absolute δ34S values cannot be calculated without further standard, samples were analyzed relative to demonstrably isotopically homogeneous fragments of Durango apatite. Zoned apatite cores displayed δ34S variation well outside of analytical uncertainty. Analytical errors on individual isotopic measurements were ± 1.5‰ and reproducibility on standard grains through the analytical session was ± 0.5‰. Grains mounted parallel and perpendicular to the C axis displayed no discernible isotopic fractionation. Cores with high S concentrations displayed isotopic enrichment in 34S up to 11‰ relative to rims and core-free grains. Concentration variations may track trajectories of S solubility in evolving magmas (Ducea et al., 1994). Meanwhile heavier S isotopic ratios may suggest either dynamic crystallization/resorption behavior of S bearing species or an oxidizing environment for these earliest crystallizing apatites.

Occupational hygiene in a Finnish drum composting plant.

PubMed

Tolvanen, Outi; Nykänen, Jenni; Nivukoski, Ulla; Himanen, Marina; Veijanen, Anja; Hänninen, Kari

2005-01-01

Bioaerosols (microbes, dust and endotoxins) and volatile organic compounds (VOCs) were determined in the working air of a drum composting plant treating source-separated catering waste. Different composting activities at the Oulu drum composting plant take place in their own units separated by modular design and constructions. Important implication of this is that the control room is a relatively clean working environment and the risk of exposure to harmful factors is low. However, the number of viable airborne microbes was high both in the biowaste receiving hall and in the drum composting hall. The concentration (geometric average) of total microbes was 21.8 million pcs/m3 in the biowaste receiving hall, 13.9 million pcs/m3 in the drum composting hall, and just 1.4 million pcs/m3 in the control room. Endotoxin concentrations were high in the biowaste receiving hall and in the drum composting hall. The average (arithmetic) endotoxin concentration was over the threshold value of 200 EU/m3 in both measurement locations. In all working areas, the average (arithmetic) dust concentrations were in a low range of 0.6-0.7 mg/m3, being below the Finnish threshold value of 5 mg/m3. In the receiving hall and drum composting hall, the concentrations of airborne microbes and endotoxins may rise to levels hazardous to health during prolonged exposure. It is advisable to use a respirator mask (class P3) in these areas. Detected volatile organic compounds were typical compounds of composting plants: carboxylic acids and their esters, alcohols, ketones, aldehydes, and terpenes. Concentrations of VOCs were much lower than the Finnish threshold limit values (Finnish TLVs), many of the quantified compounds exceeded their threshold odour concentrations (TOCs). Primary health effects due VOCs were not presumable at these concentrations but unpleasant odours may cause secondary symptoms such as nausea and hypersensitivity reactions. This situation is typical of composting plants where the workers are exposed to dozens of VOCs simultaneously. The odour units (OU/m3) were measured using olfactometer. The numbers were 23,000 OU/m3 at the output end of the composting drum and 6300 OU/m3 in the exhaust pipe. Inside the composting hall, the number of odour units was 500 and 560 OU/m3.

Quantifying the impact of septic tank systems on eutrophication risk in rural headwaters.

PubMed

Withers, P J A; Jarvie, H P; Stoate, C

2011-04-01

Septic tank systems (STS) are a potential source of nutrient emissions to surface waters but few data exist in the UK to quantify their significance for eutrophication. We monitored the impact of STS on nutrient concentrations in a stream network around a typical English village over a 1-year period. Septic tank effluent discharging via a pipe directly into one stream was highly concentrated in soluble N (8-63mgL(-1)) and P (<1-14mgL(-1)) and other nutrients (Na, K, Cl, B and Mn) typical of detergent and household inputs. Ammonium-N (NH(4)N) and soluble reactive P (SRP) fractions were dominant (70-85% of total) and average concentrations of nitrite-N (NO(2)N) were above levels considered harmful to fish (0.1mgL(-1)). Lower nutrient concentrations were recorded at a ditch and a stream site, but range and average values downstream of rural habitation were still 4 to 10-fold greater than those in upstream sections. At the ditch site, where flow volumes were low, annual flow-weighted concentrations of NH(4)N and SRP increased from 0.04 and 0.07mgL(-1), respectively upstream to 0.55 and 0.21mgL(-1) downstream. At the stream site, flow volumes were twice as large and flow-weighted concentrations increased much less; from 0.04 to 0.21mgL(-1) for NH(4)N and from 0.06 to 0.08mgL(-1) for SRP. At all sites, largest nutrient concentrations were recorded under low flow and stream discharge was the most important factor determining the eutrophication impact of septic tank systems. The very high concentrations, intercorrelation and dilution patterns of SRP, NH(4)-N and the effluent markers Na and B suggested that soakaways in the heavy clay catchment soils were not retaining and treating the septic tank effluents efficiently, with profound implications for stream biodiversity. Water companies, water regulators and rural communities therefore need to be made more aware of the potential impacts of STS on water quality so that their management can be optimised to reduce the risk of potential eutrophication and toxicity to aquatic ecosystems during summer low flow periods. Copyright © 2011 Elsevier Ltd. All rights reserved.

Geochemistry of metal-rich brines from central Mississippi Salt Dome basin, U.S.A.

USGS Publications Warehouse

Kharaka, Y.K.; Maest, A.S.; Carothers, W.W.; Law, L.M.; Lamothe, P.J.; Fries, T.L.

1987-01-01

Oil-field brines are the most favored ore-forming solutions for the sediment-hosted Mississippi Valley-type ore deposits. Detailed inorganic and organic chemical and isotope analyses of water and gas samples from six oil fields in central Mississippi, one of the very few areas with high metal brines, were conducted to study the inorganic and organic complexes responsible for the high concentrations of these metals. The samples were obtained from production zones consisting of sandstone and limestone that range in depth from 1900 to 4000 m (70-120??C) and in age from Late Cretaceous to Late Jurassic. Results show that the waters are dominantly bittern brines related to the Louann Salt. The brines have extremely high salinities that range from 160,000 to 320,000 mg/l total dissolved solids and are NaCaCl-type waters with very high concentrations of Ca (up to 48,000 mg/l) and other alkaline-earth metals, but with low concentrations of aliphatic acid anions. The concentrations of metals in many water samples are very high, reaching values of 70 mg/l for Pb, 245 mg/l for Zn, 465 mg/l for Fe and 210 mg/l for Mn. The samples with high metal contents have extremely low concentrations (<0.02 mg/l) of H2S. Samples obtained from the Smackover Formation (limestone) have low metal contents that are more typical of oil-field waters, but have very high concentrations (up to 85 mg/l) of H2S. Computations with the geochemical code SOLMINEQ.87 give the following results: (1) both Pb and Zn are present predominantly as aqueous chloride complexes (mainly as PbCl42- and ZnCl42-, respectively); (2) the concentrations of metals complexed with short-chained aliphatic acid anions and reduced S species are minor; (3) organic acid anions are important in controlling the concentrations of metals because they affect the pH and buffer capacity of the waters at subsurface conditions; and (4) galena and sphalerite solubilities control the concentrations of Pb and Zn in these waters. ?? 1988.

Effects of commonly used cooking practices on total mercury concentration in fish and their impact on exposure assessments.

PubMed

Morgan, J N; Berry, M R; Graves, R L

1997-01-01

The effects of cooking practices commonly used by Native Americans on total mercury concentrations in fish were investigated. A preparation factor relating mercury concentrations in fish as prepared for consumption to mercury concentration data as measured in typical environmental monitoring programs was calculated. Preparation factors are needed to provide risk assessors with a more accurate estimate of the actual amount of mercury ingested through consumption of contaminated fish. Data on fish preparation and consumption practices of two communities of Chippewa residing on the shores of Lake Superior in northern Wisconsin were used to select practices for study. The most commonly consumed species, walleye and lake trout, were selected. Whitefish livers were also selected for study. Commonly used cooking techniques including panfrying, deep-frying, baking, boiling, and smoking were duplicated in the laboratory. Total mercury concentrations were determined in fish portions before and after cooking and in a portion representative of that analyzed in programs to assess water quality (skin-on fillets). Total mercury was determined by microwave digestion-cold vapor atomic absorption spectroscopy. Mercury concentrations (wet weight basis) in panfried, baked, and boiled walleye fillets and deep-fried and baked whitefish livers ranged from 1.1 to 1.5 times higher than in corresponding raw portions. In lake trout, mercury concentrations were 1.5 to 2.0 times higher in cooked portions than in the raw portion. However, total mercury levels were constant before and after cooking, indicating the concentration effect is caused by weight (moisture and fat) loss. The addition of lemon juice to potentially release mercury from its bound state and promote volatilization did not exert any measurable influence on mercury concentrations in cooked walleye. In some cases mercury concentrations were increased with increased cooking times due to further loss of moisture and fat. Preparation factors (defined as the ratio of mercury concentration in cooked fish to the mercury concentration in the environmental portion) ranged from 1.3 to 2.0. Results suggest that consideration be given to the use of preparation factors in risk assessments, exposure assessments, or issuance of fish advisories where mercury concentration in raw fish tissue are used in conjunction with cooked fish meal sizes.

Determination of Mercury Content in a Shallow Firn Core from Summit, Greenland by Isotope Dilution Inductively Coupled Plasma Mass Spectrometry

NASA Technical Reports Server (NTRS)

Mann, Jacqueline L.; Long, Stephen E.; Shuman, Christopher A.; Kelly, W. Robert

2003-01-01

The total mercury Hg content was determined in 6 cm sections of a near-surface 7 m firn core and in surrounding surface snow from Summit, Greenland (elevation: 3238 m, 72.58 N, 38.53 W) in May 2001 by isotope dilution cold-vapor inductively coupled plasma mass spectrometry (ID-CV-ICP-MS). The focus of this research was to evaluate the capability of the ID-CV-ICPMS technique for measuring trace levels of Hg typical of polar snow and firn. Highly enriched Hg-201 isotopic spike is added to approximately 10 ml melted core and thoroughly mixed. The Hg(+2) in the sample is reduced on line with tin (II) chloride (SnCl2) and the elemental Hg (Hg(0)) vapor pre-concentrated on to gold gauze using a commercial amalgam system. The Hg is then thermally desorbed and introduced into a quadrupole ICP-MS. The blank corrected Hg concentrations determined for all samples ranged from 0.25 ng/L to 1.74 ng/L (ppt) (average 0.59 ng/L plus or minus 0.28 ng/L) and fall within the range of those previously determined by Boutron et al., 1998 (less than or equal to 0.05 ng/L to 2.0 ng/L) for the Summit site. The average blank value was 0.19 ng/L plus or minus 0.045 ng/L (n=6). The Hg values specifically for the firn core range from 0.25 ng/L to 0.87 ng/L (average 0.51 ng/L plus or minus 0.13 ng/L) and show both values declining with time and larger variability in concentration in the top 1.8 m.

Aerosol mixingstate, hygroscopic growth and cloud activation efficiency during MIRAGE 2006

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

Lance, Sara; Raatikainen, T.; Onasch, Timothy B.

2013-05-15

Observations of aerosol hygroscopic growth and CCN activation spectra for submicron particles are reported for the T1 ground site outside of Mexico City during the MIRAGE 2006 campaign. K¨ohler theory is used to evaluate the characteristic water uptake coefficient, k*, for the CCN active aerosol population using both size-resolved HTMDA and size-resolved CCNc measurements. Organic mass fractions, (forg), are evaluated from size-resolved aerosol mass spectrometer (AMS) measurements, from which kAMS is inferred and compared against k*. Strong diurnal profiles of aerosol water uptake parameters and aerosol composition are observed. We find that new particle formation (NPF) events are correlated withmore » an increased k* and CCN-active fraction during the daytime, with greater impact on smaller particles. During NPF events, the number concentration of 40 nm particles acting as CCN can surpass by more than a factor of two the concentrations of 100 nm particles acting as CCN, at supersaturations of 0.51% +/- 0.06%. We also find that at 0600-0800 in the morning throughout the campaign, fresh traffic emissions result in substantial changes to the chemical distribution of the aerosol, with on average 65% externally-mixed fraction for 40 nm particles and 30% externally-mixed fraction for 100 nm particles, whereas at midday nearly all particles of both sizes can be described as “internally-mixed”. Average activation spectra and growth factor distributions are analyzed for different time periods characterizing the daytime (with and without NPF events), the early morning “rush hour”, and the entire campaign. We show that k* derived from CCNc measurements decreases as a function of size during all time periods, while the CCN-active fraction increases as a function of size. Size-resolved AMS measurements do not predict the observed trend for k* versus particle size, which can be attributed to unresolved mixing-state and the presence of refractory material not measured by the AMS. Measured k* typically ranges from 0.2 to 0.35, and organics typically make up 60-85% of the aerosol mass in the size range studied. Despite some disagreement between kAMS and kCCNc, we show that kAMS is able to describe CCN concentrations reasonably well, especially at the highest CCN concentrations. This is consistent with other CCN studies carried out in urban environments, and is partly due to the fact that the highest CCN concentrations occur during the daytime when the aerosol is internally-mixed and the organic fraction is relatively low. During the early morning rush hour, however, failing to account for the aerosol mixing state results in systematic overestimation of CCN concentrations by 50-100%.« less

EFFECTS OF COMMONLY USED COOKING PRACTICES ON TOTAL MERCURY CONCENTRATION IN FISH AND THEIR IMPACT ON EXPOSURE ASSESSMENTS

EPA Science Inventory

The effects of cooking practices commonly used by Native Americans on total mercury concentrations in fish were investigated. A preparation factor relating mercury concentrations in fish as prepared for consumption to mercury concentration data as measured in typical environmenta...

Informing Selection of Nanomaterial Concentrations for ToxCast In Vitro Testing using the Multi-Path Particle Dosimetry Model

EPA Science Inventory

Currently, little justification is provided for nanomaterial testing concentrations in in vitro assays. The in vitro concentrations typically used may be higher than those experienced in exposed humans. Selection of concentration levels for hazard evaluation based on real-world ...

Rate of local tumor progression following radiofrequency ablation of pathologically early hepatocellular carcinoma.

PubMed

Hao, Yoshiteru; Numata, Kazushi; Ishii, Tomohiro; Fukuda, Hiroyuki; Maeda, Shin; Nakano, Masayuki; Tanaka, Katsuaki

2017-05-07

To evaluate whether pathologically early hepatocellular carcinoma (HCC) exhibited local tumor progression after radiofrequency ablation (RFA) less often than typical HCC. Fifty pathologically early HCCs [tumor diameter (mm): mean, 15.8; range, 10-23; follow-up days after RFA: median, 1213; range, 216-2137] and 187 typical HCCs [tumor diameter (mm): mean, 15.6; range, 6-30; follow-up days after RFA: median, 1116; range, 190-2328] were enrolled in this retrospective study. The presence of stromal invasion (namely, tumor cell invasion into the intratumoral portal tracts) was considered to be the most important pathologic finding for the diagnosis of early HCCs. Typical HCC was defined as the presence of a hyper-vascular lesion accompanied by delayed washout using contrast-enhanced computed tomography or contrast-enhanced magnetic resonance imaging. Follow-up examinations were performed at 3-mo intervals to monitor for signs of local tumor progression. The local tumor progression rates of pathologically early HCCs and typical HCCs were then determined using the Kaplan-Meier method. During the follow-up period for the 50 pathologically early HCCs, 49 (98%) of the nodules did not exhibit local tumor progression. However, 1 nodule (2%) was associated with a local tumor progression found 636 d after RFA. For the 187 typical HCCs, 46 (24.6%) of the nodules exhibited local recurrence after RFA. The follow-up period until the local tumor progression of typical HCC was a median of 605 d, ranging from 181 to 1741 d. Among the cases with typical HCCs, local tumor progression had occurred in 7.0% (7/187), 16.0% (30/187), 21.9% (41/187) and 24.6% (46/187) of the cases at 1, 2, 3 and 4 years, respectively. Pathologically early HCC was statistically associated with a lower rate of local tumor progression, compared with typical HCC, when evaluated using a log-rank test ( P = 0.002). The rate of local tumor progression for pathologically early HCCs after RFA was significantly lower than that for typical HCCs.

Rate of local tumor progression following radiofrequency ablation of pathologically early hepatocellular carcinoma

PubMed Central

Hao, Yoshiteru; Numata, Kazushi; Ishii, Tomohiro; Fukuda, Hiroyuki; Maeda, Shin; Nakano, Masayuki; Tanaka, Katsuaki

2017-01-01

AIM To evaluate whether pathologically early hepatocellular carcinoma (HCC) exhibited local tumor progression after radiofrequency ablation (RFA) less often than typical HCC. METHODS Fifty pathologically early HCCs [tumor diameter (mm): mean, 15.8; range, 10-23; follow-up days after RFA: median, 1213; range, 216-2137] and 187 typical HCCs [tumor diameter (mm): mean, 15.6; range, 6-30; follow-up days after RFA: median, 1116; range, 190-2328] were enrolled in this retrospective study. The presence of stromal invasion (namely, tumor cell invasion into the intratumoral portal tracts) was considered to be the most important pathologic finding for the diagnosis of early HCCs. Typical HCC was defined as the presence of a hyper-vascular lesion accompanied by delayed washout using contrast-enhanced computed tomography or contrast-enhanced magnetic resonance imaging. Follow-up examinations were performed at 3-mo intervals to monitor for signs of local tumor progression. The local tumor progression rates of pathologically early HCCs and typical HCCs were then determined using the Kaplan-Meier method. RESULTS During the follow-up period for the 50 pathologically early HCCs, 49 (98%) of the nodules did not exhibit local tumor progression. However, 1 nodule (2%) was associated with a local tumor progression found 636 d after RFA. For the 187 typical HCCs, 46 (24.6%) of the nodules exhibited local recurrence after RFA. The follow-up period until the local tumor progression of typical HCC was a median of 605 d, ranging from 181 to 1741 d. Among the cases with typical HCCs, local tumor progression had occurred in 7.0% (7/187), 16.0% (30/187), 21.9% (41/187) and 24.6% (46/187) of the cases at 1, 2, 3 and 4 years, respectively. Pathologically early HCC was statistically associated with a lower rate of local tumor progression, compared with typical HCC, when evaluated using a log-rank test (P = 0.002). CONCLUSION The rate of local tumor progression for pathologically early HCCs after RFA was significantly lower than that for typical HCCs. PMID:28533668

Formation of disinfection byproducts in typical Chinese drinking water.

PubMed

Liu, Wenbo; Zhao, Yanmei; Chow, Christopher W K; Wang, Dongsheng

2011-01-01

Eight typical drinking water supplies in China were selected in this study. Both source and tap water were used to investigate the occurrence of chlorinated disinfection byproducts (DBPs), and seasonal variation in the concentrations of trihalomethanes (THMs) of seven water sources was compared. The results showed that the pollution level for source water in China, as shown by DBP formation potential, was low. The most encountered DBPs were chloroform, dichloroacetic acid, trichloroacetic acid, and chlorodibromoacetic acid. The concentration of every THMs and haloacetic acid (HAA) compound was under the limit of standards for drinking water quality. The highest total THMs concentrations were detected in spring.

Robust determination of effective atomic numbers for electron interactions with TLD-100 and TLD-100H thermoluminescent dosimeters

NASA Astrophysics Data System (ADS)

Taylor, M. L.

2011-04-01

Lithium fluoride thermoluminescent dosimeters (TLD) are the most commonly implemented for clinical dosimetry. The small physical magnitude of TLDs makes them attractive for applications such as small field measurement, in vivo dosimetry and measurement of out-of-field doses to critical structures. The most broadly used TLD is TLD-100 (LiF:Mg,Ti) and, for applications requiring higher sensitivity to low-doses, TLD-100H (LiF:Mg,Cu,P) is frequently employed. The radiological properties of these TLDs are therefore of significant interest. For the first time, in this study effective atomic numbers for radiative, collisional and total electron interaction processes are calculated for TLD-100 and TLD-100H dosimeters over the energy range 1 keV-100 MeV. This is undertaken using a robust, energy-dependent method of calculation rather than typical power-law approximations. The influence of dopant concentrations and unwanted impurities is also investigated. The two TLDs exhibit similar effective atomic numbers, ranging from approximately 5.77-6.51. Differences arising from the different dopants are most pronounced in low-energy radiative effects. The TLDs have atomic numbers approximately 1.48-2.06 times that of water. The effective atomic number of TLD-100H is consistently higher than that of TLD-100 over a broad energy range, due to the greater influence of the higher- Z dopants on the electron interaction cross sections. Typical variation in dopant concentration does not significantly influence the effective atomic number. The influence on TLD-100H is comparatively more pronounced than that on TLD-100. Contrariwise, unwanted hydroxide impurities influence TLD-100 more than TLD-100H. The effective atomic number is a key parameter that influences the radiological properties and energy response of TLDs. Although many properties of these TLDs have been studied rigorously, as yet there has been no investigation of their effective atomic numbers for electron interactions. The discrepancy between the effective atomic numbers of the TLDs and water is significantly higher than would be indicated by comparing effective atomic numbers calculated via the common - but dubious - power-law method. The mean effective numbers over the full energy range are 6.06, 6.09, 3.34 and 3.37 for TLD-100, TLD-100H, soft tissue and water respectively.

A radiological survey of the Eğrigöz granitoid, Western Anatolia/Turkey.

PubMed

Canbaz Öztürk, B; Yaprak, G; Çam, N F; Candan, O

2015-06-01

A radiological survey of the granitoid areas throughout Western Anatolia was conducted during 2007-14. As a part of this radiological survey, this article presents results obtained from Eğrigöz pluton, which lies in the northeastern region of Western Anatolia. In the investigated area, the activity measurements of the natural gamma-emitting radionuclides ((226)Ra, (232)Th and (40)K) in the granitic rock samples and soils have been carried out by means of the NaI(Tl) gamma-ray spectrometry system. The activity concentrations of the relevant natural radionuclides in the granite samples appeared in the ranges as follows: (226)Ra, 28-95 Bq kg(-1); (232)Th, 50-122 Bq kg(-1) and (40)K, 782-1365 Bq kg(-1), while the typical ranges of the (226)Ra, (232)Th and (40)K activities in the soil samples were found to be 7-184, 11-174 and 149-1622 Bq kg(-1), respectively. Based on the available data, the radiation hazard parameters associated with the surveyed rocks/soils are calculated. The corresponding absorbed dose rates in air from all those radionuclides were always much lower than 200 nGy h(-1) and did not exceed the typical range of worldwide average values noted in the UNSCEAR (2000) report. Furthermore, the data are also used for the mapping of the surface soil activity of natural radionuclides and the corresponding gamma dose rates of the surveyed area. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Used motor oil as a source of MTBE, TAME, and BTEX to ground water

USGS Publications Warehouse

Baker, R.J.; Best, E.W.; Baehr, A.L.

2002-01-01

Methyl tert-butyl ether (MTBE), the widely used gasoline oxygenate, has been identified as a common ground water contaminant, and BTEX compounds (benzene, toluene, ethylbenzene, and xylenes) have long been associated with gasoline spills. Because not all instances of ground water contamination by MTBE and BTEX can be attributed to spills or leaking storage tanks, other potential sources need to be considered. In this study, used motor oil was investigated as a potential source of these contaminants. MTBE in oil was measured directly by methanol extraction and gas chromatography using a flame ionization detector (GC/FID). Water was equilibrated with oil samples and analyzed for MTBE, BTEX, and the oxygenate tert-amyl methyl ether (TAME) by purge-and-trap concentration followed by GC/FID analysis. Raoult's law was used to calculate oil-phase concentrations of MTBE, BTEX, and TAME from aqueous-phase concentrations. MTBE, TAME, and BTEX were not detected in any of five new motor oil samples, whereas these compounds were found at significant concentrations in all six samples of the used motor oil tested for MTBE and all four samples tested for TAME and BTEX. MTBE concentrations in used motor oil were on the order of 100 mg/L. TAME concentrations ranged from 2.2 to 87 mg/L. Concentrations of benzene were 29 to 66 mg/L, but those of other BTEX compounds were higher, typically 500 to 2000 mg/L.

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.

Exploring the relationship between cortical GABA concentrations, auditory gamma-band responses and development in ASD: Evidence for an altered maturational trajectory in ASD.

PubMed

Port, Russell G; Gaetz, William; Bloy, Luke; Wang, Dah-Jyuu; Blaskey, Lisa; Kuschner, Emily S; Levy, Susan E; Brodkin, Edward S; Roberts, Timothy P L

2017-04-01

Autism spectrum disorder (ASD) is hypothesized to arise from imbalances between excitatory and inhibitory neurotransmission (E/I imbalance). Studies have demonstrated E/I imbalance in individuals with ASD and also corresponding rodent models. One neural process thought to be reliant on E/I balance is gamma-band activity (Gamma), with support arising from observed correlations between motor, as well as visual, Gamma and underlying GABA concentrations in healthy adults. Additionally, decreased Gamma has been observed in ASD individuals and relevant animal models, though the direct relationship between Gamma and GABA concentrations in ASD remains unexplored. This study combined magnetoencephalography (MEG) and edited magnetic resonance spectroscopy (MRS) in 27 typically developing individuals (TD) and 30 individuals with ASD. Auditory cortex localized phase-locked Gamma was compared to resting Superior Temporal Gyrus relative cortical GABA concentrations for both children/adolescents and adults. Children/adolescents with ASD exhibited significantly decreased GABA+/Creatine (Cr) levels, though typical Gamma. Additionally, these children/adolescents lacked the typical maturation of GABA+/Cr concentrations and gamma-band coherence. Furthermore, children/adolescents with ASD additionally failed to exhibit the typical GABA+/Cr to gamma-band coherence association. This altered coupling during childhood/adolescence may result in Gamma decreases observed in the adults with ASD. Therefore, individuals with ASD exhibit improper local neuronal circuitry maturation during a childhood/adolescence critical period, when GABA is involved in configuring of such circuit functioning. Provocatively a novel line of treatment is suggested (with a critical time window); by increasing neural GABA levels in children/adolescents with ASD, proper local circuitry maturation may be restored resulting in typical Gamma in adulthood. Autism Res 2017, 10: 593-607. © 2016 International Society for Autism Research, Wiley Periodicals, Inc. © 2016 International Society for Autism Research, Wiley Periodicals, Inc.

Evaluation of potentially significant increase of lead in the blood during long-term bed rest and space flight.

PubMed

Kondrashov, Vladislav; Rothenberg, Stephen J; Chettle, David; Zerwekh, Joseph

2005-02-01

We address a gap in the knowledge of lead turnover under conditions of prolonged bed rest and microgravity by developing a quantitative model of the amount of lead returned to blood circulation from bone. We offer the hypothesis that skeletal unloading, such as typically occurs during extended bed rest or microgravity, will result in bone lead being released to the blood, as has already been demonstrated in the case of calcium. We use initial bone lead concentrations to develop predictive models of blood lead elevation. Our theoretical calculations with typical bone lead loads measured in today's 40-60-year-old generation, suggest that the estimated blood lead concentrations in long duration (e.g., 100 days) space flight could average between 20 and 40 microg dl(-1), a range with well-established toxic effects. For a similar duration of bed rest, estimated blood lead concentration could be as high as 10-20 microg dl(-1), which is a level of concern, particularly if we consider females of childbearing age. The preliminary experimental results were obtained under multi-institutional collaborations, with the main outcome received from an on-going bed rest study, Prevention of Microgravity-Induced Stone Risk by KMgCitrate, conducted at the General Clinical Research Center (GCRC) of the University of Texas Southwestern Medical Center, Dallas. Based on theoretical modeling and some preliminary experimental results, this concept may have important clinical implications by allowing prediction of the magnitude of blood lead elevation, thereby establishing the means to prevent lead toxicity during long duration space flight of astronauts and in conditions of prolonged bed rest such as complicated pregnancy, spinal cord injury induced paralysis and comatose patients.

The relevance of the slope for concentration-effect relations

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

Schobben, H.P.M.; Smit, M.; Schobben, J.H.M.

1995-12-31

Risk analysis is mostly based on a comparison of one value for the exposure to a chemical (PEC) and one value for the sensitivity of biota (NEC). This method enables the determination of an effect to be expected, but it is not possible to quantify the magnitude of that effect. Moreover, it is impossible to estimate the effect of a combination of chemicals. Therefore, it is necessary to use a mathematical function to describe the relation between a concentration and the subsequent effect. These relations are typically based on a log normal or log logistic distribution of the sensitivity ofmore » individuals of a species. This distribution is characterized by the median sensitivity (EC{sub 50}) and the variation between the sensitivity of individuals (being a measure for the slope of the relation). Presently the attention is focused on the median, while the slope might be even more important. Relevant exposure concentrations are typically in the range which are found in the left tail of the sensitivity distribution. In this study the slope was determined for 250 chemical-species combinations. The data were derived from original experiments and from literature. The slope is highly dependent on the exposure time; the shorter the exposure time the steeper the slope. If data for a standard exposure time [96 hours] are considered, the total variation in slope can partly be explained by the groups of organisms and chemicals. The slope for heavy metals tends to be less steep as compared to the slope of narcotic organic compounds. The slope for fish and molluscs is steeper than for crustaceans. The results of this study are presently applied in a number of risk analysis studies.« less

Suppression of cytokine release by fluticasone furoate vs. mometasone furoate in human nasal tissue ex-vivo.

PubMed

Zhang, Nan; Van Crombruggen, Koen; Holtappels, Gabriele; Lan, Feng; Katotomichelakis, Michail; Zhang, Luo; Högger, Petra; Bachert, Claus

2014-01-01

Topical glucocorticosteroids are the first line therapy for airway inflammation. Modern compounds with higher efficacy have been developed, but head-to-head comparison studies are sparse. To compare the activity of two intranasal glucocorticoids, fluticasone furoate (FF) and mometasone furoate (MF) with respect to the inhibition of T helper (Th)1, Th2 and Th17 cytokine release in airway mucosa. We used an ex-vivo human nasal mucosal tissue model and employed pre- and post- Staphylococcus aureus enterotoxin B (SEB)-challenge incubations with various time intervals and drug concentrations to mimic typical clinical situations of preventive or therapeutic use. At a fixed concentration of 10-10 M, FF had significantly higher suppressive effects on interferon (IFN)-γ, interleukin (IL)-2 and IL-17 release, but not IL-5 or tumor necrosis factor (TNF)-α, vs. MF. While the maximal suppressive activity was maintained when FF was added before or after tissue stimulation, the cytokine suppression capacity of MF appeared to be compromised when SEB-induced cell activation preceded the addition of the drug. In a pre-challenge incubation setting with removal of excess drug concentrations, MF approached inhibition of IL-5 and TNF-α after 6 and 24 hours while FF maximally blocked the release of these cytokines right after pre-incubation. Furthermore, FF suppressed a wider range of T helper cytokines compared to MF. The study demonstrates the potential of our human mucosal model and shows marked differences in the ability to suppress the release of various cytokines in pre- and post-challenge settings between FF and MF mimicking typical clinical situations of preventive or therapeutic use.

Copper toxicity in the spiny dogfish (Squalus acanthias): urea loss contributes to the osmoregulatory disturbance.

PubMed

De Boeck, G; Hattink, J; Franklin, N M; Bucking, C P; Wood, S; Walsh, P J; Wood, C M

2007-08-30

Previous research showed that the spiny dogfish, Squalus acanthias, is much more sensitive to silver exposure than typical marine teleosts. The aim of the present study was to investigate if spiny dogfish were equally sensitive to copper exposure and whether the toxic mechanisms were the same. We exposed cannulated and non-cannulated spiny dogfish to measured concentrations of Cu (nominally 0, 500, 1000 and 1500 microg L(-1) Cu) for 72-96 h. All Cu exposures induced acidosis and lactate accumulation of either a temporary (500 microg L(-1)) or more persistent nature (1000 and 1500 microg L(-1)). At the two highest Cu concentrations, gill Na(+)/K(+)-ATPase activities were reduced by 45% (1000 microg L(-1)) and 62% (1500 microg L(-1)), and plasma Na(+) and Cl(-) concentrations increased by approximately 50 mM each. At the same time urea excretion doubled and plasma urea dropped by approximately 100 mM. Together with plasma urea, plasma TMAO levels dropped proportionally, indicating that the general impermeability of the gills was compromised. Overall plasma osmolarity did not change. Cu accumulation was limited with significant increases in plasma Cu and elevated gill and kidney Cu burdens at 1000 and 1500 microg L(-1). We conclude that Cu, like Ag, exerts toxic effect on Na(+)/K(+)-ATPase activities in the shark similar to those of teleosts, but there is an additional toxic action on elasmobranch urea retention capacities. With a 96 h LC(50) in the 800-1000 microg L(-1) range, overall sensitivity of spiny dogfish for Cu is, in contrast with its sensitivity to Ag, only slightly lower than in typical marine teleosts.

Dimensional and chemical characterization of particles at a downwind receptor site of a waste-to-energy plant

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

Buonanno, G., E-mail: buonanno@unicas.i; Stabile, L.; Avino, P.

2010-07-15

In the last years numerous epidemiological studies were carried out to evaluate the effects of particulate matter on human health. In industrialized areas, anthropogenic activities highly contribute to the fine and ultrafine particle concentrations. Then, it is important to characterize the evolution of particle size distribution and chemical composition near these emission points. Waste incineration represents a favorable technique for reducing the waste volume. However, in the past, municipal waste incinerators (MWIs) had a bad reputation due to the emission of toxic combustion byproducts. Consequently, the risk perception of the people living near MWIs is very high even if inmore » Western countries waste incineration has nowadays to be considered a relatively clean process from a technical point of view. The study here presented has an exemplary meaning for developing appropriate management and control strategies for air quality in the surrounding of MWIs and to perform exposure assessment for populations involved. Environment particles were continuously measured through a SMPS/APS system over 12 months. The monitoring site represents a downwind receptor of a typical MWI. Furthermore, elements and organic fractions were measured by means of the Instrumental Neutron Activation Analysis and using dichotomous and high volume samplers. Annual mean values of 8.6 x 10{sup 3} +- 3.7 x 10{sup 2} part. cm{sup -3} and 31.1 +- 9.0 mug m{sup -3} were found for number and mass concentration, typical of a rural site. Most of the elements can be attributed to long-range transport from other natural and/or anthropogenic sources. Finally, the Polycyclic Aromatic Hydrocarbons present low concentrations with a mean value of 24.6 ng m{sup -3}.« less

Technical note: False low turbidity readings from optical probes during high suspended-sediment concentrations

NASA Astrophysics Data System (ADS)

Voichick, Nicholas; Topping, David J.; Griffiths, Ronald E.

2018-03-01

Turbidity, a measure of water clarity, is monitored for a variety of purposes including (1) to help determine whether water is safe to drink, (2) to establish background conditions of lakes and rivers and detect pollution caused by construction projects and stormwater discharge, (3) to study sediment transport in rivers and erosion in catchments, (4) to manage siltation of water reservoirs, and (5) to establish connections with aquatic biological properties, such as primary production and predator-prey interactions. Turbidity is typically measured with an optical probe that detects light scattered from particles in the water. Probes have defined upper limits of the range of turbidity that they can measure. The general assumption is that when turbidity exceeds this upper limit, the values of turbidity will be constant, i.e., the probe is pegged; however, this assumption is not necessarily valid. In rivers with limited variation in the physical properties of the suspended sediment, at lower suspended-sediment concentrations, an increase in suspended-sediment concentration will cause a linear increase in turbidity. When the suspended-sediment concentration in these rivers is high, turbidity levels can exceed the upper measurement limit of an optical probe and record a constant pegged value. However, at extremely high suspended-sediment concentrations, optical turbidity probes do not necessarily stay pegged at a constant value. Data from the Colorado River in Grand Canyon, Arizona, USA, and a laboratory experiment both demonstrate that when turbidity exceeds instrument-pegged conditions, increasing suspended-sediment concentration (and thus increasing turbidity) may cause optical probes to record decreasing false turbidity values that appear to be within the valid measurement range of the probe. Therefore, under high-turbidity conditions, other surrogate measurements of turbidity (e.g., acoustic-attenuation measurements or suspended-sediment samples) are necessary to correct these low false turbidity measurements and accurately measure turbidity.

Technical note: False low turbidity readings from optical probes during high suspended-sediment concentrations

USGS Publications Warehouse

Voichick, Nicholas; Topping, David; Griffiths, Ronald

2018-01-01

Turbidity, a measure of water clarity, is monitored for a variety of purposes including (1) to help determine whether water is safe to drink, (2) to establish background conditions of lakes and rivers and detect pollution caused by construction projects and stormwater discharge, (3) to study sediment transport in rivers and erosion in catchments, (4) to manage siltation of water reservoirs, and (5) to establish connections with aquatic biological properties, such as primary production and predator–prey interactions. Turbidity is typically measured with an optical probe that detects light scattered from particles in the water. Probes have defined upper limits of the range of turbidity that they can measure. The general assumption is that when turbidity exceeds this upper limit, the values of turbidity will be constant, i.e., the probe is pegged; however, this assumption is not necessarily valid. In rivers with limited variation in the physical properties of the suspended sediment, at lower suspended-sediment concentrations, an increase in suspended-sediment concentration will cause a linear increase in turbidity. When the suspended-sediment concentration in these rivers is high, turbidity levels can exceed the upper measurement limit of an optical probe and record a constant pegged value. However, at extremely high suspended-sediment concentrations, optical turbidity probes do not necessarily stay pegged at a constant value. Data from the Colorado River in Grand Canyon, Arizona, USA, and a laboratory experiment both demonstrate that when turbidity exceeds instrument-pegged conditions, increasing suspended-sediment concentration (and thus increasing turbidity) may cause optical probes to record decreasing false turbidity values that appear to be within the valid measurement range of the probe. Therefore, under high-turbidity conditions, other surrogate measurements of turbidity (e.g., acoustic-attenuation measurements or suspended-sediment samples) are necessary to correct these low false turbidity measurements and accurately measure turbidity.

Method for measuring changes in light absorption of highly scattering media

DOEpatents

Bigio, Irving J.; Johnson, Tamara M.; Mourant, Judith R.

2002-01-01

The noninvasive measurement of variations in absorption that are due to changes in concentrations of biochemically relevant compounds in tissue is important in many clinical settings. One problem with such measurements is that the pathlength traveled by the collected light through the tissue depends on the scattering properties of the tissue. It is demonstrated, using both Monte Carlo simulations and experimental measurements, that for an appropriate separation between light-delivery and light-collection fibers, the pathlength of the collected photons is insensitive to scattering parameters for the range of parameters typically found in tissue. This is important for developing rapid, noninvasive, inexpensive, and accurate methods for measuring absorption changes in tissue.

The mineralogical transformation of a polymetallic sulfide ore during partial roasting

NASA Astrophysics Data System (ADS)

Evrard, Louis

2001-12-01

A partial desulfurization roasting process has been tested on a typical copper-zinc sulfide concentrate in a Nichols Herreshoff monohearth pilot furnace. In this process, the sulfur is partially removed and iron, to a certain degree, is preferentially oxidized. The mineralogical characterizations of the reaction products at different residence times enable the recognition of a sequence of reactions and various textural relationships during the roasting. The testing showed that a controlled desulfurization at a temperature as low as 650°C can lead to the decomposition of chalcopyrite, resulting in the formation of discrete particles of Cu2S having a size ranging from five to 20 micrometers or more.

Line active hybrid lipids determine domain size in phase separation of saturated and unsaturated lipids.

PubMed

Brewster, Robert; Safran, Samuel A

2010-03-17

A simple model of the line activity of a hybrid lipid (e.g., POPC) with one fully saturated chain and one partially unsaturated chain demonstrates that these lipids preferentially pack at curved interfaces between phase-separated saturated and unsaturated domains. We predict that the domain sizes typically range from tens to hundreds of nm, depending on molecular interactions and parameters such as molecular volume and area per headgroup in the bulk fluid phase. The role of cholesterol is taken into account by an effective change in the headgroup areas and the domain sizes are predicted to increase with cholesterol concentration. Copyright 2010 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Production of Carbon Occluded in Phytolith Is Season-Dependent in a Bamboo Forest in Subtropical China

PubMed Central

Huang, Zhang-Ting; Jiang, Pei-Kun; Chang, Scott Xiaochuan; Zhang, Yan; Ying, Yu-Qi

2014-01-01

Carbon (C) occluded in phytolith (PhytOC) is a stable form of C; when PhytOC is returned to the soil through litterfall it is stored in the soil which can be an effective way for long-term C sequestration. However, few estimates on the rate of PhytOC input to the soil are available. To better understand the seasonal dynamics of PhytOC production and the annual rate of stable C sequestration through PhytOC input, we quantified the monthly litterfall, phytolith and PhytOC return to the soil over a year in a typical Lei bamboo (Phyllostachys praecox) forest in subtropical China. The monthly litterfall ranged between 14.81 and 131.18 g m−2, and the phytolith concentration in the monthly litterfall samples ranged between 47.21 and 101.68 g kg−1 of litter mass, with the PhytOC concentration in the phytolith ranged between 29.4 and 44.9 g kg−1 of phytolith, equivalent to 1.8–3.6 g kg−1 of PhytOC in the litterfall (based on litterfall dry mass). The amount of phytolith input to the soil system was 292.21±69.12 (mean±SD) kg ha−1 yr−1, sequestering 41.45±9.32 kg CO2−e ha−1 yr−1 of C in the studied Lei bamboo forest. This rate of C sequestration through the formation of PhytOC found in this study falls within the range of rates for other grass-type species reported in the literature. We conclude that return of C occluded in phytolith to the soil can be a substantial source of stable soil C and finding means to increase PhytOC storage in the soil should be able to play a significant role in mitigating the rapidly increasing atmospheric CO2 concentration. PMID:25188462

Landscape linkages between geothermal activity and solute composition and ecological response in surface waters draining the Atlantic slope of Costa Rica

USGS Publications Warehouse

Pringle, Catherine M.; Rowe, Gary L.; Triska, Frank J.; Fernandez, Jose F.; West, John

1993-01-01

Surface waters draining three different volcanoes in Costa Rica, ranging from dormant to moderately active to explosive, have a wide range of solute compositions that partly reflects the contribution of different types of solute-rich, geothermal waters. Three major physical transport vectors affect flows of geothermally derived solutes: thermally driven convection of volcanic gases and geothermal fluids; lateral and gravity-driven downward transport of geothermal fluids; and wind dispersion of ash, gases, and acid rain. Specific vector combinations interact to determine landscape patterns in solute chemistry and biota: indicator taxa of algae and bacteria reflect factors such as high temperature, wind-driven or hydrologically transported acidity, high concentrations of various solutes, and chemical precipitation reactions. Many streams receiving geothermally derived solutes have high levels of soluble reactive phosphorus (SRP) (up to 400 µg liter−1), a nutrient that is typically not measured in geochemical studies of geothermal waters. Regional differences in levels of SRP and other solutes among volcanoes were typically not significant due to high local variation in solute levels among geothermally modified streams and between geothermally modified and unmodified streams on each volcano. Geothermal activity along the volcanic spine of Costa Rica provides a natural source of phosphorus, silica, and other solutes and plays an important role in determining emergent landscape patterns in the solute chemistry of surface waters and aquatic biota.

Spectroscopic analysis of high protein nigella seeds (Kalonji) using laser-induced breakdown spectroscopy and inductively coupled plasma/optical emission spectroscopy

NASA Astrophysics Data System (ADS)

Rehan, Imran; Khan, M. Zubair; Ali, Irfan; Rehan, Kamran; Sultana, Sabiha; Shah, Sher

2018-03-01

The spectroscopic analysis of high protein nigella seeds (also called Kalonji) was performed using pulsed nanosecond laser-induced breakdown spectroscopy (LIBS) at 532 nm. The emission spectrum of Kalonji recorded with an LIBS spectrometer exposed the presence of various elements like Al, B, Ba, Ca, Cr, K, P, Mg, Mn, Na, Ni, S, Si, Cu, Fe, Ti, Sn, Sr, and Zn. The plasma parameters (electron temperature and electron density) were estimated using Ca-I spectral lines and their behavior were studied against laser irradiance. The electron temperature and electron density was observed to show an increasing trend in the range of 5802-7849 K, and (1.2-3.9) × 1017 cm- 3, respectively, in the studied irradiance range of (1.2-12.6) × 109 W/cm2. Furthermore, the effect of varying laser energy on the integrated signal intensities was also studied. The quantitative analysis of the detected elements was performed via the calibration curves drawn for all the observed elements through typical samples made in the known concentration in the Kalonji matrix, and by setting the concentration of P as the calibration. The validity of our LIBS findings was verified via comparison of the results with the concentration of every element find in Kalonji using the standard analytical tool like ICP/OES. The results acquired using LIBS and ICP/OES were found in fine harmony. Moreover, limit of detection was measured for toxic metals only.

Eu(III)-Fulvic Acid Complexation: Evidence of Fulvic Acid Concentration Dependent Interactions by Time-Resolved Luminescence Spectroscopy.

PubMed

Kouhail, Yasmine Z; Benedetti, Marc F; Reiller, Pascal E

2016-04-05

Europium speciation is investigated by time-resolved luminescence spectroscopy (TRLS) in the presence of Suwannee River fulvic acid (SRFA). From complexation isotherms built at different total Eu(III) concentrations, pH values, ionic strength, and SRFA concentrations, it appears that two luminescence behaviors of Eu(III) are occurring. The first part, at the lowest CSRFA values, is showing the typical luminescence evolution of Eu(III) complexed by humic substances--that is, the increase of the asymmetry ratio between the (5)D0 → (7)F2 and (5)D0 → (7)F1 transitions up to a plateau--, and the occurrence of a biexponential decay--the first decay being faster than free Eu(3+). At higher CSRFA, a second luminescence mode is detected as the asymmetry ratio is increasing again after the previous plateau, and could correspond to the formation of another type of complex, and/or it can reflect a different spatial organization of complexed europium within the SRFA structure. The luminescence decay keeps on evolving but link to hydration number is not straightforward due to quenching mechanisms. The Eu(III) chemical environment evolution with CSRFA is also ionic strength dependent. These observations suggest that in addition to short-range interactions--intraparticulate complexation--, there might be interactions at longer range--interparticulate repulsion--between particles that are complexing Eu(III) at high CSRFA. These interactions are not yet accounted by the different complexation models.

Whole-Organism Concentration Ratios for Plutonium in Wildlife from Past US Nuclear Research Data

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

johansen, M.; Kamboj; Kuhne, W.

Whole-organism concentration ratios (CR{sub wo-media}) for plutonium (Pu) in wildlife were calculated using data from the broad range of organism types and environmental settings of the US nuclear research program. Original sources included site-specific reports and scientific journal articles typically from 1960s to 80s research. Most of the calculated CR{sub wo-media} values are new to existing data sets, and, for some wildlife categories, serve to fill gaps or add to sparse data including those for terrestrial reptile; freshwater bird, crustacean and zooplankton; and marine crustacean and zooplankton. Ratios of Pu concentration in the whole-organism to that in specific tissues andmore » organs are provided here for a range of freshwater and marine fish. The CR{sub wo-media} values in fish living in liquid discharge ponds were two orders of magnitude higher than those for similar species living in lakes receiving Pu from atmospheric fallout, suggesting the physico-chemical form of the source Pu can dominate over other factors related to transfer, such as organism size and feeding behavior. Small rodent data indicated one to two order of magnitude increases when carcass, pelt, and gastrointestinal tract were included together in the whole-organism calculation compared to that for carcass alone. Only 4% of Pu resided in the carcass of small rodents compared to 75% in the gastrointestinal tract and 21% in the pelt.« less

Occurrence and Removal Characteristics of Phthalate Esters from Typical Water Sources in Northeast China

PubMed Central

Liu, Yu; Chen, Zhonglin; Shen, Jimin

2013-01-01

The presence of phthalate esters (PAEs) in the environment has gained a considerable attention due to their potential impacts on public health. This study reports the first data on the occurrence of 15 PAEs in the water near the Mopanshan Reservoir—the new and important water source of Harbin city in Northeast China. As drinking water is a major source for human exposure to PAEs, the fate of target PAEs in the two waterworks (Mopanshan Waterworks and Seven Waterworks) was also analyzed. The results demonstrated that the total concentrations of 15 PAEs in the water near the Mopanshan Reservoir were relatively moderate, ranging from 355.8 to 9226.5 ng/L, with the mean value of 2943.1 ng/L. DBP and DEHP dominated the PAE concentrations, which ranged from 52.5 to 4498.2 ng/L and 128.9 to 6570.9 ng/L, respectively. The occurrence and concentrations of these compounds were heavily spatially dependent. Meanwhile, the results on the waterworks samples suggested no significant differences in PAE levels with the input of the raw waters. Without effective and stable removal of PAEs after the conventional drinking water treatment in the waterworks (25.8% to 76.5%), the risks posed by PAEs through drinking water ingestion were still existing, which should be paid special attention to the source control in the Mopanshan Reservoir and some advanced treatment processes for drinking water supplies. PMID:23577281

Particulate organic compounds in the atmosphere surrounding an industrialised area of Prato (Italy)

NASA Astrophysics Data System (ADS)

Cincinelli, Alessandra; Mandorlo, Stefano; Dickhut, Rebecca M.; Lepri, Luciano

Atmospheric aerosols were collected during the period from May 2000 through January 2001 at 13 different sites in and around the Baciacavallo sewage treatment plant in Prato (Italy). The urban area surrounding the plant contains significant textile industrial activity and a main arterial road. Aerosol-associated n-alkane, polycyclic aromatic hydrocarbon (PAH), nonylphenol (NP) and nonylphenolethoxylate (NPnEO) ( n=1-3) concentrations were measured in order to evaluate contributions from the sewage treatment plant, naturally produced aerosols, transportation and industrial activities to the air quality in the vicinity of the sewage treatment plant. Aerosol-associated n-alkane concentrations ranged from 36.7 to 205 ng/m 3 and their possible origin was determined by the presence of typical petroleum characteristics such as the unresolved complex mixture and an odd/even carbon ratio (Carbon Preference Index). PAH concentrations ranged from 0.855 to 24.2 ng/m 3, in accordance with those generally found for urban aerosols in Europe. NP and NPnEO ( n=1-3), as well as fine aerosol particulate matter (PM 10) were significantly correlated with relative wind direction with increased levels observed in the ambient atmosphere when the relative wind direction was from the Baciacavallo sewage treatment plant. This study confirms the use of NP and NPnEO ( n=1-3) as markers of sewage treatment emissions and the importance of the contribution of aerosols produced by sewage treatment plant aeration tanks to the local atmospheric composition.

Development of a sensor for temperature and water concentration in combustion gases using a single tunable diode laser

NASA Astrophysics Data System (ADS)

Zhou, Xin; Liu, Xiang; Jeffries, Jay B.; Hanson, R. K.

2003-08-01

The water vapour spectrum in the 1-2 µm near-infrared region is systematically analysed to find the best absorption transitions for sensitive measurement of H2O concentration and temperature in combustion environments using a single tunable diode laser with typical distributed feedback single-mode scanning range (1 cm-1). The use of a single laser, even with relatively narrow tuning range, can offer distinct advantages over wavelength-multiplexing techniques. The strategy and spectroscopic criteria for selecting optimum wavelength regions and absorption line combinations are discussed. It should be stressed that no single figure of merit can be derived to simplify the selection process, and the optimum line pair should be chosen case by case. Our investigation reveals that the 1.8 µm spectral region is especially promising, and we have identified 10 of the best water line pairs in this spectral region for temperature measurements in flames. Based on these findings, a pair of H2O transitions near 1.8 µm was targeted for the design and development of an initial single-laser sensor for simultaneously measuring H2O concentration and temperature in atmospheric-pressure flames. As part of the sensor development effort, fundamental spectroscopic parameters including the line strength, line-centre frequency and lower state energies of the probed transitions were measured experimentally to improve the current databases. We conclude with demonstration results in a steady and a forced atmospheric-pressure laboratory combustor.

Effect of age, decentration, aberrations and pupil size on subjective image quality with concentric bifocal optics.

PubMed

Rio, David; Woog, Kelly; Legras, Richard

2016-07-01

We investigated the impact of lens centration, wearer aberrations, pupil size and age on the optics of two bifocal contact lenses using image simulation. Fourteen conditions (i.e. two optical profiles with two and eight concentric zones; two conditions of centration: centred and 0.77 mm decentred; and three conditions of aberrations: 0, 0.15 and 0.35 μm RMS; three pupil sizes: 3, 4.5 and 6 mm) were tested on two populations (i.e. 20-40 and 40-60 years old) using a numerical simulation method. For each condition, images were calculated for proximities ranging from -4D to + 2D with steps of 0.25D. Subjects graded the quality of each simulated image (i.e. a target 'HEV' of 0.4 logMAR) on a continuous scale from 0 to 5. To limit the effect of the observer's own aberrations, subjects viewed the displayed images through a 3-mm pupil and their optimal correction. Both populations reported similar image quality (i.e. average absolute difference of 0.23) except for sharp and low contrast images, which obtained slightly higher grades with younger subjects, probably due to a better contrast sensitivity in this population. Typical decentration had no effect on bifocal contact lenses wearers' vision, as the ratio between areas dedicated to near and distance vision did not change. Aberrations (i.e. mainly 0.24 μm of spherical aberration on a 4.5-mm pupil) reduced the addition of the two radial zones bifocal optics and introduced a hyperopic shift (i.e. 0.50D) of the through-focus image quality for the eight radial zone bifocal lens. The combination of typical aberrations with typical decentration created the same effect as typical aberrations alone, meaning that aberration impact was stronger than decentration impact. The two radial zone bifocal lens was dependent on the pupil whereas the eight radial zone lens was not. When fitting new bifocal optics, the aberrations of the patients, as well as their pupil diameter, are the main subject dependent parameters influencing quality of vision. Typical contact lens decentration and lower cortical treatment efficiency of retinal images of older subjects had relatively little impact. © 2016 The Authors Ophthalmic & Physiological Optics © 2016 The College of Optometrists.

Polycyclic aromatic hydrocarbons and organochlorine pesticides in rice hull from a typical e-waste recycling area in southeast China: temporal trend, source, and exposure assessment.

PubMed

Liu, Fang; Liao, Chunyang; Fu, Jianjie; Lv, Jungang; Xue, Qinzhao; Jiang, Guibin

2014-02-01

The residue levels of 16 US EPA priority polycyclic aromatic hydrocarbons (PAHs) and 16 selected organochlorine pesticides (OCPs) in rice and rice hull collected from a typical e-waste recycling area in southeast China were investigated from 2005 to 2007. PAHs and OCPs also were measured in ten mollusk species (soft tissues) collected in an adjacent bay in 2007. Individual PAHs were frequently found in the entire sample set (including the rice, hull, and mollusk samples) with a detection rate of 73 %. The total concentrations of 16 PAHs (ΣPAHs) and 16 OCPs (ΣOCPs) were in the range of 40.8-432 ng/g dry weight (mean: 171 ng/g) and 2.35-925 ng/g (122 ng/g), respectively, which were comparable or higher than those reported in some polluted areas. Statistical comparisons suggested that the concentrations of contaminants in hull gradually decreased from 2005 to 2007 and the residue levels were generally in the order of mollusk, hull, and rice, on a dry weight basis. Principal component analysis in combination with diagnostic ratios implied that combustion of coal, wood, and plastic wastes that are closely associated with crude e-waste recycling activities is the main source of PAHs. The finding of decreasing trend of concentrations of PAHs in this area is consistent with the efforts of local authorities to strengthen regulations on illegal e-waste recycling activities. Composition analysis suggested that there is a recent usage or discharge of hexachlorocyclohexane and dichlorodiphenyltrichloroethane into the tested area. The estimated daily intake (EDI) of ΣPAHs and ΣOCPs (calculated from mean concentrations) through rice and mollusk consumption was 0.411 and 0.921 μg/kg body weight (bw)/day, respectively.

A comparison of the dietary arsenic exposures from ingestion of contaminated soil and hyperaccumulating Pteris ferns used in a residential phytoremediation project.

PubMed

Ebbs, Stephen; Hatfield, Sarah; Nagarajan, Vinay; Blaylock, Michael

2010-01-01

Arsenic (As) hyperaccumulating ferns are used to phytoremediate As-contaminated soils, including soils in residential areas. This use may pose a health risk if children were to ingest these plants. Spider brake (Pteris cretica L.) plants were grown in sand spiked with arsenate, to produce tissue As concentrations (2000-4500 mg kg DW(-1)) typical of those observed in plants deployed for As phytoremediation. The fronds were subjected to a physiologically-based extraction test to estimate As bioaccessibility, which ranged from 3.4-20.5%. A scenario for human dietary exposure to As in an urban setting was then estimated for a child consuming 0.25 g DW of tissue. The calculation of dietary exposure took into account the As concentration in the fern pinnae, the bioaccessibility of As in the tissue, and the typical absorption of inorganic As by the gastrointestinal tract. The pinnae As concentrations and the calculated dietary exposures were used to create a non-linear regression model relating tissue As concentration to dietary exposure. Data from a phytoremediation project in a residential area using Pteris cretica and Pteris vittata (L.) were input into this model to project dietary As exposure in a residential phytoremediation setting. These exposures were compared to estimates of dietary As exposure from the consumption of soil. The results showed that dietary exposures to As from consumption of soil or pinnae tissue were similar and that estimates of dietary exposure were below the LOAEL value of 14 microg As kg(-1) d(-1). The results suggest that the hyperaccumulation of As in Pteris ferns during growth in moderately contaminated residential soils (e.g., < or = 100 mg As kg DW(-1)) does not represent an inherent risk or a risk substantially different from that posed by accidental ingestion of contaminated soil.

Model Parameter Variability for Enhanced Anaerobic Bioremediation of DNAPL Source Zones

NASA Astrophysics Data System (ADS)

Mao, X.; Gerhard, J. I.; Barry, D. A.

2005-12-01

The objective of the Source Area Bioremediation (SABRE) project, an international collaboration of twelve companies, two government agencies and three research institutions, is to evaluate the performance of enhanced anaerobic bioremediation for the treatment of chlorinated ethene source areas containing dense, non-aqueous phase liquids (DNAPL). This 4-year, 5.7 million dollars research effort focuses on a pilot-scale demonstration of enhanced bioremediation at a trichloroethene (TCE) DNAPL field site in the United Kingdom, and includes a significant program of laboratory and modelling studies. Prior to field implementation, a large-scale, multi-laboratory microcosm study was performed to determine the optimal system properties to support dehalogenation of TCE in site soil and groundwater. This statistically-based suite of experiments measured the influence of key variables (electron donor, nutrient addition, bioaugmentation, TCE concentration and sulphate concentration) in promoting the reductive dechlorination of TCE to ethene. As well, a comprehensive biogeochemical numerical model was developed for simulating the anaerobic dehalogenation of chlorinated ethenes. An appropriate (reduced) version of this model was combined with a parameter estimation method based on fitting of the experimental results. Each of over 150 individual microcosm calibrations involved matching predicted and observed time-varying concentrations of all chlorinated compounds. This study focuses on an analysis of this suite of fitted model parameter values. This includes determining the statistical correlation between parameters typically employed in standard Michaelis-Menten type rate descriptions (e.g., maximum dechlorination rates, half-saturation constants) and the key experimental variables. The analysis provides insight into the degree to which aqueous phase TCE and cis-DCE inhibit dechlorination of less-chlorinated compounds. Overall, this work provides a database of the numerical modelling parameters typically employed for simulating TCE dechlorination relevant for a range of system conditions (e.g, bioaugmented, high TCE concentrations, etc.). The significance of the obtained variability of parameters is illustrated with one-dimensional simulations of enhanced anaerobic bioremediation of residual TCE DNAPL.

Nicotine Concentration of E-Cigarettes Used by Adolescents

PubMed Central

Morean, Meghan E.; Kong, Grace; Cavallo, Dana A.; Camenga, Deepa R.; Krishnan-Sarin, Suchitra

2016-01-01

Objective E-cigarettes are popular among youth, but little is known about the nicotine concentrations of e-liquids used by adolescents. Materials and Method In Spring, 2014, we conducted cross-sectional surveys in four Connecticut high schools and two middle schools. Among past-30-day e-cigarette users (n = 513, 45% female, mean age 15.9 [SD=1.4]), we examined what nicotine concentration adolescents typically used in their e-cigarettes (range 0-30mg/mL and “I don’t know”). We first examined whether age, sex, smoking status, e-cigarette use frequency, and/or e-cigarette acquisition source were associated with using nicotine-free e-liquid, nicotine e-liquid, or not knowing the e-liquid nicotine concentration. Among nicotine users (n = 185), we then examined whether the aforementioned variables were associated with using higher nicotine concentrations. Results Adolescents reported using nicotine-free e-liquid (28.5%), nicotine e-liquid (37.4%), or not knowing their e-liquid nicotine concentration (34.1%). Nicotine users comprised more smokers and heavier e-cigarette users compared to nicotine-free e-liquid users and those who did not know their nicotine concentration. Nicotine users also comprised more males and were more likely to purchase e-cigarettes online or from tobacco shops compared to those who did not know their nicotine concentration. Among nicotine users, cigarette smoking, male sex, and purchasing e-cigarettes from tobacco shops predicted using higher nicotine concentrations. Conclusions Adolescents reported using e-liquids with variable nicotine concentrations. Smokers, males, and those who purchased their own e-cigarettes reported using the highest nicotine levels. Of concern, many adolescents were unaware of the nicotine concentration in their e-liquid, raising concerns about inadvertent nicotine exposure among youth. PMID:27592270

Nicotine concentration of e-cigarettes used by adolescents.

PubMed

Morean, Meghan E; Kong, Grace; Cavallo, Dana A; Camenga, Deepa R; Krishnan-Sarin, Suchitra

2016-10-01

E-cigarettes are popular among youth, but little is known about the nicotine concentrations of e-liquids used by adolescents. In Spring, 2014, we conducted cross-sectional surveys in four Connecticut high schools and two middle schools. Among past-30-day e-cigarette users (n=513, 45% female, mean age 15.9 [SD=1.4]), we examined what nicotine concentration adolescents typically used in their e-cigarettes (range 0-30mg/mL and "I don't know"). We first examined whether age, sex, smoking status, e-cigarette use frequency, and/or e-cigarette acquisition source were associated with using nicotine-free e-liquid, nicotine e-liquid, or not knowing the e-liquid nicotine concentration. Among nicotine users (n=185), we then examined whether the aforementioned variables were associated with using higher nicotine concentrations. Adolescents reported using nicotine-free e-liquid (28.5%), nicotine e-liquid (37.4%), or not knowing their e-liquid nicotine concentration (34.1%). Nicotine users comprised more smokers and heavier e-cigarette users compared to nicotine-free e-liquid users and those who did not know their nicotine concentration. Nicotine users also comprised more males and were more likely to purchase e-cigarettes online or from tobacco shops compared to those who did not know their nicotine concentration. Among nicotine users, cigarette smoking, male sex, and purchasing e-cigarettes from tobacco shops predicted using higher nicotine concentrations. Adolescents reported using e-liquids with variable nicotine concentrations. Smokers, males, and those who purchased their own e-cigarettes reported using the highest nicotine levels. Of concern, many adolescents were unaware of the nicotine concentration in their e-liquid, raising concerns about inadvertent nicotine exposure among youth. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Winter measurements of trace gas and aerosol composition at a rural site in southern ontario

NASA Astrophysics Data System (ADS)

Daum, P. H.; Kelly, T. J.; Tanner, R. L.; Tang, X.; Anlauf, K.; Bottenheim, J.; Brice, K. A.; Wiebe, H. A.

This paper reports the results of continuous measurements of concentrations of trace gas and aerosol species at Powassan, Ontario, a rural location in southern Ontario, from 20 January to 24 February 1984. The measurements included aerosol H + , NH 4+, Na +, Ca 2+ , NO 3-, SO 42- and Cl -, gaseous SO 2, NO, NO' y; ( = NO + NO2 + PAN + HNO3), HNO 3, PAN, and O 3. Average values of concentrations for key species during the project were: SO 2, 7.3 ppb; NO y, 7.5 ppb; HNO 3, 0.85 ppb; O 3, 33 ppb; NH 4+ 1.5 ppb; NO 3-, 0.4 ppb; and SO 42-, 0.9 ppb. Concentrations of primary pollutants (e.g. SO 2) were typically much higher, and concentrations of secondary species (e.g. SO 42-) typically lower, than observed at this location in summer. However, clear-air t- NO 3-/SO 42- ratios averaged 5-10 times higher in winter than in summer which suggests that HNO 3 is a more important source of atmospheric acidity, relative to SO 42- aerosol, in winter than in summer. Pollutant concentrations were highly variable; back trajectory calculations indicate that periods of high concentrations of both primary and secondary species were typically associated with air-mass back trajectories from the southern sectors while periods of low concentrations of secondary species were associated with back trajectories from the north. Comparison of these measurements with those at other locations suggests that concentrations at Powassan were characteristic of those prevailing over a much larger, possibly regional, area.

Relationship between water and aragonite barium concentrations in aquaria reared juvenile corals

USGS Publications Warehouse

Gonneea, Meagan; Cohen, Anne L.; DeCarlo, Thomas M.; Charette, Matthew A.

2017-01-01

Coral barium to calcium (Ba/Ca) ratios have been used to reconstruct records of upwelling, river and groundwater discharge, and sediment and dust input to the coastal ocean. However, this proxy has not yet been explicitly tested to determine if Ba inclusion in the coral skeleton is directly proportional to seawater Ba concentration and to further determine how additional factors such as temperature and calcification rate control coral Ba/Ca ratios. We measured the inclusion of Ba within aquaria reared juvenile corals (Favia fragum) at three temperatures (∼27.7, 24.6 and 22.5 °C) and three seawater Ba concentrations (73, 230 and 450 nmol kg−1). Coral polyps were settled on tiles conditioned with encrusting coralline algae, which complicated chemical analysis of the coral skeletal material grown during the aquaria experiments. We utilized Sr/Ca ratios of encrusting coralline algae (as low as 3.4 mmol mol−1) to correct coral Ba/Ca for this contamination, which was determined to be 26 ± 11% using a two end member mixing model. Notably, there was a large range in Ba/Ca across all treatments, however, we found that Ba inclusion was linear across the full concentration range. The temperature sensitivity of the distribution coefficient is within the range of previously reported values. Finally, calcification rate, which displayed large variability, was not correlated to the distribution coefficient. The observed temperature dependence predicts a change in coral Ba/Ca ratios of 1.1 μmol mol−1 from 20 to 28 °C for typical coastal ocean Ba concentrations of 50 nmol kg−1. Given the linear uptake of Ba by corals observed in this study, coral proxy records that demonstrate peaks of 10–25 μmol mol−1 would require coastal seawater Ba of between 60 and 145 nmol kg−1. Further validation of the coral Ba/Ca proxy requires evaluation of changes in seawater chemistry associated with the environmental perturbation recorded by the coral as well as verification of these results for Porites species, which are widely used in paleo reconstructions.

Airborne Measurements of CO2 Column Concentration and Range Using a Pulsed Direct-Detection IPDA Lidar

NASA Technical Reports Server (NTRS)

Abshire, James B.; Ramanathan, Anand; Riris, Haris; Mao, Jianping; Allan, Graham R.; Hasselbrack, William E.; Weaver, Clark J.; Browell, Edward V.

2013-01-01

We have previously demonstrated a pulsed direct detection IPDA lidar to measure range and the column concentration of atmospheric CO2. The lidar measures the atmospheric backscatter profiles and samples the shape of the 1,572.33 nm CO2 absorption line. We participated in the ASCENDS science flights on the NASA DC-8 aircraft during August 2011 and report here lidar measurements made on four flights over a variety of surface and cloud conditions near the US. These included over a stratus cloud deck over the Pacific Ocean, to a dry lake bed surrounded by mountains in Nevada, to a desert area with a coal-fired power plant, and from the Rocky Mountains to Iowa, with segments with both cumulus and cirrus clouds. Most flights were to altitudes >12 km and had 5-6 altitude steps. Analyses show the retrievals of lidar range, CO2 column absorption, and CO2 mixing ratio worked well when measuring over topography with rapidly changing height and reflectivity, through thin clouds, between cumulus clouds, and to stratus cloud tops. The retrievals shows the decrease in column CO2 due to growing vegetation when flying over Iowa cropland as well as a sudden increase in CO2 concentration near a coal-fired power plant. For regions where the CO2 concentration was relatively constant, the measured CO2 absorption lineshape (averaged for 50 s) matched the predicted shapes to better than 1% RMS error. For 10 s averaging, the scatter in the retrievals was typically 2-3 ppm and was limited by the received signal photon count. Retrievals were made using atmospheric parameters from both an atmospheric model and from in situ temperature and pressure from the aircraft. The retrievals had no free parameters and did not use empirical adjustments, and >70% of the measurements passed screening and were used in analysis. The differences between the lidar-measured retrievals and in situ measured average CO2 column concentrations were <1.4 ppm for flight measurement altitudes >6 km.

A Model to Predict the Breathing Zone Concentrations of Particles Emitted from Surfaces

EPA Science Inventory

Activity based sampling (ABS) is typically performed to assess inhalation exposure to particulate contaminants known to have low, heterogeneous concentrations on a surface. Activity based sampling determines the contaminant concentration in a person's breathing zone as they perfo...

United role of radon decay products and nano-aerosols in radon dosimetry

NASA Astrophysics Data System (ADS)

Smerajec, M.; Vaupotič, J.

2012-04-01

The major part of human exposure to natural radiation originates from inhalation of radon (Rn) and radon short-lived decay products (RnDP: 218Po, 214Pb, 214Bi and 214Po). RnDP are formed as a result of α-transformation of radon. In the beginning they are positive ions which neutralize and form clusters with air molecules, and later partly attach to background aerosol particles in indoor air. Eventually, they appear as radioactive nano-aerosols with a bimodal size distribution in ranges of 1-10 nm (unattached RnDP) and of 200-800 nm (attached RnDP). When inhaled, they are deposited in the respiratory tract. Deposition is more efficient for smaller particles. Therefore, the fraction (fun) of the unattached RnDP, which appears to be influenced by the number concentration and size distribution of general (background) aerosols in the ambient air, has a crucial role in radon dosimetry. Radon, radon decay products and general aerosols have been monitored simultaneously in the kitchen of a typical rural house under real living conditions, also comprising four human activities generating particular matter: cooking and baking, as two typical activities in kitchen, and cigarette smoking and candle burning. In periods without any human activity, the total number concentration of general aerosol ranged from 1000 to 3000 cm-3,with the geometric mean of particle diameter in the range of 60-68 nm and with 0.1-1 % of particles smaller than 10 nm. Preparation of coffee changed the concentration to 193,000 cm-3, the geometric mean of diameter to 20 nm and fraction of particles smaller than 10 nm to 11 %. The respective changes were for baking cake: 503,000 cm-3, 17 nm and 19 %, for smoking:423,000 cm-3, 83 nm and 0.4 %, and forcandle burning: 945,000 cm-3, 8 nm and 85 %. While, as expected, a reduction of fun was observed during cooking, baking and smoking, when larger particles were emitted, fun did not increase during candle burning with mostly particles smaller than 10 nm produced. Because the processes of RnDP creation by radioactive transformation, their neutralization, clustering and association with aerosol particles need time, the response of fun on the changes in general aerosol is delayed in time and therefore fun response on the fast changes, such as those caused by short human activities, may be obscured and even not observed.

Formation of lobate debris aprons on Mars: Assessment of regional ice sheet collapse and debris-cover armoring

NASA Astrophysics Data System (ADS)

Fastook, James L.; Head, James W.; Marchant, David R.

2014-01-01

Lobate debris aprons (LDA) are lobate-shaped aprons surrounding scarps and isolated massifs that are concentrated in the vicinity of the northern Dichotomy Boundary on Mars. LDAs have been interpreted as (1) ice-cemented talus aprons undergoing viscous flow, (2) local debris-covered alpine-like glaciers, or (3) remnants of the collapse of a regional retreating ice sheet. We investigate the plausibility that LDAs are remnants of a more extensive regional ice sheet by modeling this process. We find that as a regional ice sheet collapses, the surface drops below cliff and massif bedrock margins, exposing bedrock and regolith, and initiating debris deposition on the surface of a cold-based glacier. Reduced sublimation due to debris-cover armoring of the proto-LDA surface produces a surface slope and consequent ice flow that carries the armoring debris away from the rock outcrops. As collapse and ice retreat continue the debris train eventually reaches the substrate surface at the front of the glacier, leaving the entire LDA armored by debris cover. Using a simplified ice flow model we are able to characterize the temperature and sublimation rate that would be necessary to produce LDAs with a wide range of specified lateral extents and thicknesses. We then apply this method to a database of documented LDA parameters (height, lateral extent) from the Dichotomy Boundary region, and assess the implications for predicted climate conditions during their formation and the range of formation times implied by the model. We find that for the population examined here, typical temperatures are in the range of -85 to -40 °C and typical sublimation rates lie in the range of 6-14 mm/a. Lobate debris apron formation times (from the point of bedrock exposure to complete debris cover) cluster near 400-500 ka. These results show that LDA length and thickness characteristics are consistent with climate conditions and a formation scenario typical of the collapse of a regional retreating ice sheet and exposure of bedrock cliffs. This scenario helps resolve many of the unusual characteristics of lobate debris aprons (LDA) and lineated valley fill (LVF). For example, the distribution of LVF is very consistent with extensive flow of glacial ice from plateau icefields, and the acquisition of a debris cover in the waning stages of retreat of the regional cover as the bedrock scarps are exposed. The typical concentric development of LDA around massifs is much more consistent with ice sheet retreat than insolation-related local accumulation and flow. We thus conclude that the retreating ice-sheet model is robust and should be investigated and tested in more detail. In addition, these results clearly show that the lobate debris aprons in the vicinity of the Dichotomy Boundary could not have attained temperatures near or above the ice melting point and retained their current shape, a finding that supports subzero temperatures for the last several hundred million years, the age of the LDA surfaces. A further implication is that the LDA ice has been preserved for at least several hundred million years, and could potentially contain the record of the climate of Mars, preserved since that time below a sublimation lag deposit.

Pushing down the low-mass halo concentration frontier with the Lomonosov cosmological simulations

NASA Astrophysics Data System (ADS)

Pilipenko, Sergey V.; Sánchez-Conde, Miguel A.; Prada, Francisco; Yepes, Gustavo

2017-12-01

We introduce the Lomonosov suite of high-resolution N-body cosmological simulations covering a full box of size 32 h-1 Mpc with low-mass resolution particles (2 × 107 h-1 M⊙) and three zoom-in simulations of overdense, underdense and mean density regions at much higher particle resolution (4 × 104 h-1 M⊙). The main purpose of this simulation suite is to extend the concentration-mass relation of dark matter haloes down to masses below those typically available in large cosmological simulations. The three different density regions available at higher resolution provide a better understanding of the effect of the local environment on halo concentration, known to be potentially important for small simulation boxes and small halo masses. Yet, we find the correction to be small in comparison with the scatter of halo concentrations. We conclude that zoom simulations, despite their limited representativity of the volume of the Universe, can be effectively used for the measurement of halo concentrations at least at the halo masses probed by our simulations. In any case, after a precise characterization of this effect, we develop a robust technique to extrapolate the concentration values found in zoom simulations to larger volumes with greater accuracy. Altogether, Lomonosov provides a measure of the concentration-mass relation in the halo mass range 107-1010 h-1 M⊙ with superb halo statistics. This work represents a first important step to measure halo concentrations at intermediate, yet vastly unexplored halo mass scales, down to the smallest ones. All Lomonosov data and files are public for community's use.

Distinct molecular targets including SLO-1 and gap junctions are engaged across a continuum of ethanol concentrations in Caenorhabditis elegans

PubMed Central

Dillon, James; Andrianakis, Ioannis; Mould, Richard; Ient, Ben; Liu, Wei; James, Christopher; O'Connor, Vincent; Holden-Dye, Lindy

2013-01-01

Ethanol (alcohol) interacts with diverse molecular effectors across a range of concentrations in the brain, eliciting intoxication through to sedation. Invertebrate models including the nematode worm Caenorhabditis elegans have been deployed for molecular genetic studies to inform on key components of these alcohol signaling pathways. C. elegans studies have typically employed external dosing with high (>250 mM) ethanol concentrations: A careful analysis of responses to low concentrations is lacking. Using the C. elegans pharyngeal system as a paradigm, we report a previously uncharacterized continuum of cellular and behavioral responses to ethanol from low (10 mM) to high (300 mM) concentrations. The complexity of these responses indicates that the pleiotropic action of ethanol observed in mammalian brain is conserved in this invertebrate model. We investigated two candidate ethanol effectors, the calcium-activated K+ channel SLO-1 and gap junctions, and show that they contribute to, but are not sole determinants of, the low- and high-concentration effects, respectively. Notably, this study shows cellular and whole organismal behavioral responses to ethanol in C. elegans that directly equate to intoxicating through to supralethal blood alcohol concentrations in humans and provides an important benchmark for interpretation of paradigms that seek to inform on human alcohol use disorders.—Dillon, J., Andrianakis, I., Mould, R., Ient, B., Liu, W., James, C., O'Connor, V., Holden-Dye, L. Distinct molecular targets including SLO-1 and gap junctions are engaged across a continuum of ethanol concentrations in Caenorhabditis elegans. PMID:23882127

A reversed-phase high-performance liquid chromatography method for bovine serum albumin assay in pharmaceutical dosage forms and protein/antigen delivery systems.

PubMed

Hamidi, Mehrdad; Zarei, Najmeh

2009-05-01

Bovine serum albumin (BSA) is among the most widely used proteins in protein formulations as well as in the development of novel delivery systems as a typical model for therapeutic/diagnostic proteins and the new versions of vaccines. The development of reliable and easily available assay methods for quantitation of this protein would therefore play a crucial role in these types of studies. A simple gradient reversed-phase high-performance liquid chromatography with ultra-violet detection (HPLC-UV) method has been developed for quantitation of BSA in dosage forms and protein delivery systems. The method produced linear responses throughout the wide BSA concentration range of 1 to 100 micro g/mL. The average within-run and between-run variations of the method within the linear concentration range of BSA were 2.46% and 2.20%, respectively, with accuracies of 104.49% and 104.58% for within-run and between-run samples, respectively. The limits of detection (LOD) and quantitation (LOQ) of the method were 0.5 and 1 microg/mL, respectively. The method showed acceptable system suitability indices, which enabled us to use it successfully during our particulate vaccine delivery research project. Copyright 2009 John Wiley & Sons, Ltd.

Fluorescence hyperspectral imaging (fHSI) using a spectrally resolved detector array

PubMed Central

Luthman, Anna Siri; Dumitru, Sebastian; Quiros‐Gonzalez, Isabel; Joseph, James

2017-01-01

Abstract The ability to resolve multiple fluorescent emissions from different biological targets in video rate applications, such as endoscopy and intraoperative imaging, has traditionally been limited by the use of filter‐based imaging systems. Hyperspectral imaging (HSI) facilitates the detection of both spatial and spectral information in a single data acquisition, however, instrumentation for HSI is typically complex, bulky and expensive. We sought to overcome these limitations using a novel robust and low cost HSI camera based on a spectrally resolved detector array (SRDA). We integrated this HSI camera into a wide‐field reflectance‐based imaging system operating in the near‐infrared range to assess the suitability for in vivo imaging of exogenous fluorescent contrast agents. Using this fluorescence HSI (fHSI) system, we were able to accurately resolve the presence and concentration of at least 7 fluorescent dyes in solution. We also demonstrate high spectral unmixing precision, signal linearity with dye concentration and at depth in tissue mimicking phantoms, and delineate 4 fluorescent dyes in vivo. Our approach, including statistical background removal, could be directly generalised to broader spectral ranges, for example, to resolve tissue reflectance or autofluorescence and in future be tailored to video rate applications requiring snapshot HSI data acquisition. PMID:28485130

Phytoremediation of arsenic contaminated soil by Pteris vittata L. I. Influence of phosphatic fertilizers and repeated harvests.

PubMed

Mandal, Asit; Purakayastha, T J; Patra, A K; Sanyal, S K

2012-12-01

A greenhouse experiment was conducted to evaluate the effectiveness of diammonium phosphate (DAP), single superphosphate (SSP) and two growing cycles on arsenic removal by Chinese Brake Fern (Pteris vittata L.) from an arsenic contaminated Typic Haplustept of the Indian state of West Bengal. After harvest of Pteris vittata the total, Olsen's extractable and other five soil arsenic fractions were determined. The total biomass yield of P. vittata ranged from 10.7 to 16.2 g pot(-1) in first growing cycle and from 7.53 to 11.57 g pot(-1) in second growing cycle. The frond arsenic concentrations ranged from 990 to 1374 mg kg(-1) in first growing cycle and from 875 to 1371 mg kg(-1) in second growing cycle. DAP was most efficient in enhancing biomass yield, frond and root arsenic concentrations and total arsenic removal from soil. After first growing cycle, P. vittata reduced soil arsenic by 10 to 20%, while after two growing cycles Pteris reduced it by 18 to 34%. Among the different arsenic fractions, Fe-bound arsenic dominated over other fractions. Two successive harvests with DAP as the phosphate fertilizer emerged as the promising management strategy for amelioration of arsenic contaminated soil of West Bengal through phyotoextraction by P. vittata.

Optimization of cellulose nanocrystal length and surface charge density through phosphoric acid hydrolysis

NASA Astrophysics Data System (ADS)

Vanderfleet, Oriana M.; Osorio, Daniel A.; Cranston, Emily D.

2017-12-01

Cellulose nanocrystals (CNCs) are emerging nanomaterials with a large range of potential applications. CNCs are typically produced through acid hydrolysis with sulfuric acid; however, phosphoric acid has the advantage of generating CNCs with higher thermal stability. This paper presents a design of experiments approach to optimize the hydrolysis of CNCs from cotton with phosphoric acid. Hydrolysis time, temperature and acid concentration were varied across nine experiments and a linear least-squares regression analysis was applied to understand the effects of these parameters on CNC properties. In all but one case, rod-shaped nanoparticles with a high degree of crystallinity and thermal stability were produced. A statistical model was generated to predict CNC length, and trends in phosphate content and zeta potential were elucidated. The CNC length could be tuned over a relatively large range (238-475 nm) and the polydispersity could be narrowed most effectively by increasing the hydrolysis temperature and acid concentration. The CNC phosphate content was most affected by hydrolysis temperature and time; however, the charge density and colloidal stability were considered low compared with sulfuric acid hydrolysed CNCs. This study provides insight into weak acid hydrolysis and proposes `design rules' for CNCs with improved size uniformity and charge density. This article is part of a discussion meeting issue `New horizons for cellulose nanotechnology'.

Quantum cascade laser-based sensor system for nitric oxide detection

NASA Astrophysics Data System (ADS)

Tittel, Frank K.; Allred, James J.; Cao, Yingchun; Sanchez, Nancy P.; Ren, Wei; Jiang, Wenzhe; Jiang, Dongfang; Griffin, Robert J.

2015-01-01

Sensitive detection of nitric oxide (NO) at ppbv concentration levels has an important impact in diverse fields of applications including environmental monitoring, industrial process control and medical diagnostics. For example, NO can be used as a biomarker of asthma and inflammatory lung diseases such as chronic obstructive pulmonary disease. Trace gas sensor systems capable of high sensitivity require the targeting of strong rotational-vibrational bands in the mid-IR spectral range. These bands are accessible using state-of-the-art high heat load (HHL) packaged, continuous wave (CW), distributed feedback (DFB) quantum cascade lasers (QCLs). Quartz-enhanced photoacoustic spectroscopy (QEPAS) permits the design of fast, sensitive, selective, and compact sensor systems. A QEPAS sensor was developed employing a room-temperature CW DFB-QCL emitting at 5.26 μm with an optical excitation power of 60 mW. High sensitivity is achieved by targeting a NO absorption line at 1900.08 cm-1 free of interference by H2O and CO2. The minimum detection limit of the sensor is 7.5 and 1 ppbv of NO with 1and 100 second averaging time respectively . The sensitivity of the sensor system is sufficient for detecting NO in exhaled human breath, with typical concentration levels ranging from 24.0 ppbv to 54.0 ppbv.

Sequential assessment via daphnia and zebrafish for systematic toxicity screening of heterogeneous substances.

PubMed

Jang, Gun Hyuk; Park, Chang-Beom; Kang, Benedict J; Kim, Young Jun; Lee, Kwan Hyi

2016-09-01

Environment and organisms are persistently exposed by a mixture of various substances. However, the current evaluation method is mostly based on an individual substance's toxicity. A systematic toxicity evaluation of heterogeneous substances needs to be established. To demonstrate toxicity assessment of mixture, we chose a group of three typical ingredients in cosmetic sunscreen products that frequently enters ecosystems: benzophenone-3 (BP-3), ethylhexyl methoxycinnamate (EHMC), and titanium dioxide nanoparticle (TiO2 NP). We first determined a range of nominal toxic concentration of each ingredient or substance using Daphnia magna, and then for the subsequent organismal level phenotypic assessment, chose the wild-type zebrafish embryos. Any phenotype change, such as body deformation, led to further examinations on the specific organs of transgenic zebrafish embryos. Based on the systematic toxicity assessments of the heterogeneous substances, we offer a sequential environmental toxicity assessment protocol that starts off by utilizing Daphnia magna to determine a nominal concentration range of each substance and finishes by utilizing the zebrafish embryos to detect defects on the embryos caused by the heterogeneous substances. The protocol showed additive toxic effects of the mixtures. We propose a sequential environmental toxicity assessment protocol for the systematic toxicity screening of heterogeneous substances from Daphnia magna to zebrafish embryo in-vivo models. Copyright © 2016 Elsevier Ltd. All rights reserved.

Environmental occurrence and distribution of short chain chlorinated paraffins in sediments and soils from the Liaohe River Basin, P. R. China.

PubMed

Gao, Yuan; Zhang, Haijun; Su, Fan; Tian, Yuzeng; Chen, Jiping

2012-04-03

Chlorinated paraffins (CPs) are industrially produced in large quantities in the Liaohe River Basin. Their discharge inevitably causes environmental contamination. However, very limited information is available on their environmental levels and distributions in this typical industrial region. In this study, short chain CPs (SCCPs) were analyzed in sediments, paddy soils, and upland soils from the Liaohe River Basin, with concentrations ranging from 39.8 to 480.3 ng/g dry weight. A decreasing trend in SCCP concentrations was found with increasing distance from the cities, suggesting that local industrial activity was the major source of SCCP contamination. A preliminary sediment inventory of SCCPs indicated approximately 30.82 tonnes of SCCPs residual in the sediments from the Liaohe River. The average discharge of SCCPs was estimated to be about 74.4 mg/tonne industrial wastewater. The congener group profiles showed that the relative abundances of shorter chain and lower chlorinated CP congeners (C(10)-CPs with 5 or 6 chlorine atoms) in soils in rural areas were higher than in sites near cities, which demonstrated that long-range atmospheric transportation could be the major transport pathway. Environmental degradation of SCCPs might occur, where higher chlorinated congeners could dechlorinate to form the lower chlorinated congeners.

Holographic lens spectrum splitting photovoltaic system for increased diffuse collection and annual energy yield

NASA Astrophysics Data System (ADS)

Vorndran, Shelby D.; Wu, Yuechen; Ayala, Silvana; Kostuk, Raymond K.

2015-09-01

Concentrating and spectrum splitting photovoltaic (PV) modules have a limited acceptance angle and thus suffer from optical loss under off-axis illumination. This loss manifests itself as a substantial reduction in energy yield in locations where a significant portion of insulation is diffuse. In this work, a spectrum splitting PV system is designed to efficiently collect and convert light in a range of illumination conditions. The system uses a holographic lens to concentrate shortwavelength light onto a smaller, more expensive indium gallium phosphide (InGaP) PV cell. The high efficiency PV cell near the axis is surrounded with silicon (Si), a less expensive material that collects a broader portion of the solar spectrum. Under direct illumination, the device achieves increased conversion efficiency from spectrum splitting. Under diffuse illumination, the device collects light with efficiency comparable to a flat-panel Si module. Design of the holographic lens is discussed. Optical efficiency and power output of the module under a range of illumination conditions from direct to diffuse are simulated with non-sequential raytracing software. Using direct and diffuse Typical Metrological Year (TMY3) irradiance measurements, annual energy yield of the module is calculated for several installation sites. Energy yield of the spectrum splitting module is compared to that of a full flat-panel Si reference module.

GEOSTATISTICAL INTERPOLATION OF CHEMICAL CONCENTRATION. (R825689C037)

EPA Science Inventory

Abstract

Measurements of contaminant concentration at a hazardous waste site typically vary over many orders of magnitude and have highly skewed distributions. This work presents a practical methodology for the estimation of solute concentration contour maps and volume...

Persistent Organic Pollutants (POPs) in the atmosphere of three Chilean cities using passive air samplers.

PubMed

Pozo, Karla; Oyola, Germán; Estellano, Victor H; Harner, Tom; Rudolph, Anny; Prybilova, Petra; Kukucka, Petr; Audi, Ondrej; Klánová, Jana; Metzdorff, America; Focardi, Silvano

2017-05-15

In this study passive air samplers containing polyurethane foam (PUF) disks were deployed in three cities across Chile; Santiago (STG) (n=5, sampling sites), Concepciόn (CON) (n=6) and Temuco (TEM) (n=6) from 2008 to 2009. Polychlorinated biphenyls (PCBs) (7 indicator congeners), chlorinated pesticides hexachlorocyclohexanes (HCHs), dichlorodiphenyl trichloroethanes (DDTs) and flame retardants such as polybrominated diphenyl ethers (PBDEs) were determined by gas chromatography coupled mass spectrometry (GC/MS). A sampling rate (R) typical of urban sites (4m 3 /day) was used to estimate the atmospheric concentrations of individual compounds. PCB concentrations in the air (pg/m 3 ) ranged from ~1-10 (TEM), ~1-40 (STG) and 4-30 (CON). Higher molecular weight PCBs (PCB-153, -180) were detected at industrial sites (in Concepción). The HCHs showed a prevalence of γ-HCH across all sites, indicative of inputs from the use of lindane but a limited use of technical HCHs in Chile. DDTs were detected with a prevalence of p,p'-DDE accounting for ~50% of the total DDTs. PBDE concentrations in air (pg/m 3 ) ranged from 1 to 55 (STG), 0.5 to 20 (CON) and from 0.4 to 10 (TEM), and were generally similar to those reported for many other urban areas globally. The pattern of PBDEs was different among the three cities; however, PBDE-209 was dominant at most of the sites. These results represent one of the few assessments of air concentrations of POPs across different urban areas within the same country. These data will support Chilean commitments as a signatory to the Stockholm Convention on POPs and for reporting as a member country of the Group of Latin America and Caribbean Countries (GRULAC) region. Copyright © 2016 Elsevier B.V. All rights reserved.

Cadmium accumulations and bioavailability in soils from long-term phosphorus fertilization

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

Mulla, D.J.; Page, A.L.; Ganje, T.J.

1980-07-01

Soils from citrus groves that had been fertilized with the equivalent of approximately 175 kg P/ha per year (as treble superphosphate (TSP)) over a 36-year period were sampled and analyzed for total P, Cd, and Zn as well as water-soluble P and Cd. A P fertilization rate of 175 kg/ha is much higher than normal field rates, which are typically about 30 kg/ha. Concentrations of total Cd in surface soil were highly correlated (r = 0.89) with concentrations of total P. The concentrations of Cd in surface soil receiving broadcast P for 36 years averaged 1.0 ..mu..g/g, and were considerablymore » greater than those of the controls, which showed a mean concentration of 0.07 ..mu..g/g. Phosphorus in soil saturation paste extracts ranged from 0.10 ..mu..g/ml (controls) to 8.87 ..mu..g/ml in P fertilized soils. Water-soluble saturation extract Cd ranged from 0.008 ..mu..g/ml in controls to 0.017 ..mu..g/ml in fertilized soils, and was not well correlated with water-soluble P. Cadmium levels in barley (Hordeum vulgare var. U.C. 566) grain and leaves grown in the field on soil subject to long-term heavy P fertilization were not elevated above levels in barley grown on the control soil. Swiss chard (Beta vulgaris var. cicla) was grown in the greenhouse on the above surface soils collected from the field. Although Cd levels averaging 1.6 ..mu..g/g in plant tissue were significantly elevated over those on the control soil (0.26 ..mu..g/gm), no yield depression was observed.« less

Characteristics of petroleum contaminants and their distribution in Lake Taihu, China.

PubMed

Guo, Jixiang; Fang, Jia; Cao, Jingjing

2012-08-31

Taihu Lake is a typical plain eutrophic shallow lake. With rapidly economic development of the lake area, the petroleum products and oil wastewater produced in various processes have been inevitably discharged into Taihu Lake. As the major fresh water resource in the economically developed region of Yangtze River Delta, the water quality and environmental condition of Taihu Lake have the direct bearing on the natural environment and sustainable development of economy in this region. For this reason we carried out the study to explore the composition, distribution characteristics and sources of petroleum contaminants in Taihu Lake. The aim of this study was to provide the basis for standard management and pollution control of the Taihu Lake environment. The result showed that water samples from near industrial locations were of relatively higher petroleum contaminants concentrations. The oil pollutants concentrations in different areas of Lake Taihu ranged from 0.106 mg/L to 1.168 mg/L, and the sequence of total contents distribution characteristics of petroleum pollutants from high to low in different regions of Taihu Lake was: "Dapu", "Xiaomeikou", "Zhushan Bay", "Lake center", "Qidu". The results showed that total concentrations of n-alkanes and PAHs ranged from 0.045 to 0.281 mg/L and from 0.011 to 0.034 mg/L respectively. In the same region, the concentrations of hydrocarbon pollutants in the surface and bottom of the lake were higher than that in the middle. This paper reached a conclusion that the petroleum contaminants in Taihu Lake mainly derived from petroleum pollution caused by human activities as indicated by OEP, bimodal distribution, CPI, Pr/Ph ratio, the LMW/HMW ratio and other evaluation indices for sources of n-alkanes and polycyclic aromatic hydrocarbons (PAHs).

Air pollution and acute respiratory response in a panel of asthmatic children along the U.S.-Mexico border.

PubMed

Sarnat, Stefanie Ebelt; Raysoni, Amit U; Li, Wen-Whai; Holguin, Fernando; Johnson, Brent A; Flores Luevano, Silvia; Garcia, Jose Humberto; Sarnat, Jeremy A

2012-03-01

Concerns regarding the health impact of urban air pollution on asthmatic children are pronounced along the U.S.-Mexico border because of rapid population growth near busy border highways and roads. We conducted the first binational study of the impacts of air pollution on asthmatic children in Ciudad Juarez, Mexico, and El Paso, Texas, USA, and compared different exposure metrics to assess acute respiratory response. We recruited 58 asthmatic children from two schools in Ciudad Juarez and two schools in El Paso. A marker of airway inflammation [exhaled nitric oxide (eNO)], respiratory symptom surveys, and pollutant measurements (indoor and outdoor 48-hr size-fractionated particulate matter, 48-hr black carbon, and 96-hr nitrogen dioxide) were collected at each school for 16 weeks. We examined associations between the pollutants and respiratory response using generalized linear mixed models. We observed small but consistent associations between eNO and numerous pollutant metrics, with estimated increases in eNO ranging from 1% to 3% per interquartile range increase in pollutant concentrations. Effect estimates from models using school-based concentrations were generally stronger than corresponding estimates based on concentrations from ambient air monitors. Both traffic-related and non-traffic-related particles were typically more robust predictors of eNO than was nitrogen dioxide, for which associations were highly sensitive to model specification. Associations differed significantly across the four school-based cohorts, consistent with heterogeneity in pollutant concentrations and cohort characteristics. Models examining respiratory symptoms were consistent with the null. The results indicate adverse effects of air pollution on the subclinical respiratory health of asthmatic children in this region and provide preliminary support for the use of air pollution monitors close to schools to track exposure and potential health risk in this population.

High-field Overhauser dynamic nuclear polarization in silicon below the metal-insulator transition.

PubMed

Dementyev, Anatoly E; Cory, David G; Ramanathan, Chandrasekhar

2011-04-21

Single crystal silicon is an excellent system to explore dynamic nuclear polarization (DNP), as it exhibits a continuum of properties from metallic to insulating as a function of doping concentration and temperature. At low doping concentrations DNP has been observed to occur via the solid effect, while at very high-doping concentrations an Overhauser mechanism is responsible. Here we report the hyperpolarization of (29)Si in n-doped silicon crystals, with doping concentrations in the range of (1-3) × 10(17) cm(-3). In this regime exchange interactions between donors become extremely important. The sign of the enhancement in our experiments and its frequency dependence suggest that the (29)Si spins are directly polarized by donor electrons via an Overhauser mechanism within exchange-coupled donor clusters. The exchange interaction between donors only needs to be larger than the silicon hyperfine interaction (typically much smaller than the donor hyperfine coupling) to enable this Overhauser mechanism. Nuclear polarization enhancement is observed for a range of donor clusters in which the exchange energy is comparable to the donor hyperfine interaction. The DNP dynamics are characterized by a single exponential time constant that depends on the microwave power, indicating that the Overhauser mechanism is a rate-limiting step. Since only about 2% of the silicon nuclei are located within 1 Bohr radius of the donor electron, nuclear spin diffusion is important in transferring the polarization to all the spins. However, the spin-diffusion time is much shorter than the Overhauser time due to the relatively weak silicon hyperfine coupling strength. In a 2.35 T magnetic field at 1.1 K, we observed a DNP enhancement of 244 ± 84 resulting in a silicon polarization of 10.4 ± 3.4% following 2 h of microwave irradiation.

Carbon and nitrogen systematics in nitrogen-rich, ultradeep diamonds from Sao Luiz, Brazil

NASA Astrophysics Data System (ADS)

Navon, Oded; Stachel, Thomas; Stern, Richard A.; Harris, Jeffrey W.

2018-05-01

Three diamonds from Sao Luiz, Brazil carrying nano- and micro-inclusions of molecular δ-N2 that exsolved at the base of the transition zone were studied for their C and N isotopic composition and the concentration of N utilizing SIMS. The diamonds are individually uniform in their C isotopic composition and most spot analyses yield δ13C values of -3.2 ± 0.1‰ (ON-SLZ-390) and - 4.7 ± 0.1‰ (ON-SLZ-391 and 392). Only a few analyses deviate from these tight ranges and all fall within the main mantle range of -5 ± 3‰. Most of the N isotope analyses also have typical mantle δ15N values (-6.6 ± 0.4‰, -3.6 ± 0.5‰ and - 4.1 ± 0.6‰ for ON-SLZ-390, 391 and 392, respectively) and are associated with high N concentrations of 800-1250 atomic ppm. However, some N isotopic ratios, associated with low N concentrations (<400 ppm) and narrow zones with bright luminescence are distinctly above the average, reaching positive δ15N values. These sharp fluctuations cannot be attributed to fractionation. They may reflect arrival of new small pulses of melt or fluid that evolved under different conditions. Alternatively, they may result from fractionation between different growth directions, so that distinct δ15N values and N concentrations may form during diamond growth from a single melt/fluid. Other more continuous variations, in the core of ON-SLZ-390 or the rim of ON-SLZ-392 may be the result of Rayleigh fractionation or mixing.

Measurement and modeling of indoor air pollution in rural households with multiple stove interventions in Yunnan, China

NASA Astrophysics Data System (ADS)

Chowdhury, Zohir; Campanella, Luke; Gray, Christen; Al Masud, Abdullah; Marter-Kenyon, Jessica; Pennise, David; Charron, Dana; Zuzhang, Xia

2013-03-01

In the developing world, indoor air pollution (IAP) created from solid fuel used in traditional biomass cook stoves is a leading contributor of poor respiratory health, global burden of disease, and greenhouse pollutant emissions. In the present study, we piloted an experimental cross-sectional monitoring and evaluation design with 30 households in rural Lijiang and Deqin counties in northwest Yunnan province, China. This approach offers the ability to examine the effectiveness of improved cook stove (ICS) programs with a much smaller sample size than the typical population based pre- and post-intervention study that requires a large sample representative of the population. Continuous PM2.5 was measured with the UCB (currently known as UCB-PATS) and the TSI DustTrak and continuous CO was measured with the HOBO CO logger. Using the traditional method of cooking and heating, mean 24-h PM2.5 and CO concentrations in the kitchen were measured in the range of 0.15-0.71 mg m-3 for PM2.5 and 3.0-11 ppm for CO. These concentrations were compared to using a combination of improved stoves in the kitchen where PM2.5 and CO concentrations were measured in the range of 0.08-0.18 mg m-3 for PM2.5 and 0.7-5.5 ppm for CO. These concentrations yielded statistically significant reduction in IAP when replacing the traditional fireplace or traditional stove with an improved stove combination. Finally, we show a strong correlation between CO and PM2.5 (R2 = 0.72-0.76). The combination of this experimental design along with the monitoring and evaluation protocol presented here may provide a robust framework to rapidly assess the effectiveness of ICS interventions in progress.

The Biogeochemical Role of Baleen Whales and Krill in Southern Ocean Nutrient Cycling

PubMed Central

Ratnarajah, Lavenia; Bowie, Andrew R.; Lannuzel, Delphine; Meiners, Klaus M.; Nicol, Stephen

2014-01-01

The availability of micronutrients is a key factor that affects primary productivity in High Nutrient Low Chlorophyll (HNLC) regions of the Southern Ocean. Nutrient supply is governed by a range of physical, chemical and biological processes, and there are significant feedbacks within the ecosystem. It has been suggested that baleen whales form a crucial part of biogeochemical cycling processes through the consumption of nutrient-rich krill and subsequent defecation, but data on their contribution are scarce. We analysed the concentration of iron, cadmium, manganese, cobalt, copper, zinc, phosphorus and carbon in baleen whale faeces and muscle, and krill tissue using inductively coupled plasma mass spectrometry. Metal concentrations in krill tissue were between 20 thousand and 4.8 million times higher than typical Southern Ocean HNLC seawater concentrations, while whale faecal matter was between 276 thousand and 10 million times higher. These findings suggest that krill act as a mechanism for concentrating and retaining elements in the surface layer, which are subsequently released back into the ocean, once eaten by whales, through defecation. Trace metal to carbon ratios were also higher in whale faeces compared to whale muscle indicating that whales are concentrating carbon and actively defecating trace elements. Consequently, recovery of the great whales may facilitate the recycling of nutrients via defecation, which may affect productivity in HNLC areas. PMID:25469984

Possible causes of variation in acrylamide concentration in French fries prepared in food service establishments: an observational study.

PubMed

Sanny, M; Jinap, S; Bakker, E J; van Boekel, M A J S; Luning, P A

2012-05-01

Acrylamide is a probable human carcinogen, and its presence in a range of fried and oven-cooked foods has raised considerable health concern world-wide. Dietary intake studies observed significant variations in acrylamide concentrations, which complicate risk assessment and the establishment of effective control measures. The objective of this study was to obtain an insight into the actual variation in acrylamide concentrations in French fries prepared under typical conditions in a food service establishment (FSE). Besides acrylamide, frying time, frying temperature, and reducing sugars were measured and the actual practices at receiving, thawing and frying during French fries preparation were observed and recorded. The variation in the actual frying temperature contributed most to the variation in acrylamide concentrations, followed by the variation in actual frying time; no obvious effect of reducing sugars was found. The lack of standardised control of frying temperature and frying time (due to inadequate frying equipment) and the variable practices of food handlers seem to contribute most to the large variation and high acrylamide concentrations in French fries prepared in a restaurant type of FSE as compared to chain fast-food services, and institutional caterers. The obtained insights in this study can be used to develop dedicated control measures in FSE, which may contribute to a sustainable reduction in the acrylamide intake. Copyright © 2011 Elsevier Ltd. All rights reserved.

Rice ingestion is a major pathway for human exposure to organophosphate flame retardants (OPFRs) in China.

PubMed

Zhang, Xingli; Zou, Wei; Mu, Li; Chen, Yuming; Ren, Chaoxiu; Hu, Xiangang; Zhou, Qixing

2016-11-15

Although organophosphate flame retardants (OPFRs) have been shown to accumulate in abiotic and biotic environmental compartments, data about OPFRs concentrations in various foods are limited and are none in humans through diets. In this work, the concentrations of 6 typical OPFRs were investigated in 50 rice samples, 75 commonly consumed foods and 45 human hair samples from China. The dietary intakes of OPFRs for adult people via food ingestion were estimated. The concentrations of ΣOPFRs in foods ranged from 0.004ng/g to 287ng/g. OPFRs were detected in 53.3% of the human hair samples. The highest OPFRs concentrations were found in rice and vegetables. Tri(2-chloroethyl)phosphate(TCEP), tris(2-chloroisopropyl)phosphate(TCIPP), and tri(2-ethyltexyl)phosphate(TEHP) were predominant in all food samples. OPFRs concentrations in foods were not significantly affected by the packaging materials. The mean dietary intakes of ΣOPFRs for adult males and females were 539 and 601ng/kg body weight/day, respectively. The greatest contribution to these values is from rice, accounting for approximately 60% of the total intake, particularly from rice protein. Rice ingestion was considered a potential major pathway for human exposure to OPFRs, and regional differences in the levels of OPFRs in foods and dietary differences should be given more attention in the future. Copyright © 2016 Elsevier B.V. All rights reserved.

The biogeochemical role of baleen whales and krill in Southern Ocean nutrient cycling.

PubMed

Ratnarajah, Lavenia; Bowie, Andrew R; Lannuzel, Delphine; Meiners, Klaus M; Nicol, Stephen

2014-01-01

The availability of micronutrients is a key factor that affects primary productivity in High Nutrient Low Chlorophyll (HNLC) regions of the Southern Ocean. Nutrient supply is governed by a range of physical, chemical and biological processes, and there are significant feedbacks within the ecosystem. It has been suggested that baleen whales form a crucial part of biogeochemical cycling processes through the consumption of nutrient-rich krill and subsequent defecation, but data on their contribution are scarce. We analysed the concentration of iron, cadmium, manganese, cobalt, copper, zinc, phosphorus and carbon in baleen whale faeces and muscle, and krill tissue using inductively coupled plasma mass spectrometry. Metal concentrations in krill tissue were between 20 thousand and 4.8 million times higher than typical Southern Ocean HNLC seawater concentrations, while whale faecal matter was between 276 thousand and 10 million times higher. These findings suggest that krill act as a mechanism for concentrating and retaining elements in the surface layer, which are subsequently released back into the ocean, once eaten by whales, through defecation. Trace metal to carbon ratios were also higher in whale faeces compared to whale muscle indicating that whales are concentrating carbon and actively defecating trace elements. Consequently, recovery of the great whales may facilitate the recycling of nutrients via defecation, which may affect productivity in HNLC areas.

Formaldehyde concentrations in household air of asthma patients determined using colorimetric detector tubes

PubMed Central

Dannemiller, Karen C.; Murphy, Johnna S.; Dixon, Sherry L.; Pennell, Kelly G.; Suuberg, Eric M.; Jacobs, David E.; Sandel, Megan

2013-01-01

Formaldehyde is a colorless, pungent gas commonly found in homes that is a respiratory irritant, sensitizer, carcinogen and asthma trigger. Typical household sources include plywood and particleboard, cleaners, cosmetics, pesticides, and others. Development of a fast and simple measurement technique could facilitate continued research on this important chemical. The goal of this research is to apply an inexpensive short-term measurement method to find correlations between formaldehyde sources and concentration, and formaldehyde concentration and asthma control. Formaldehyde was measured using 30-minute grab samples in length-of-stain detector tubes in homes (n=70) of asthmatics in the Boston, MA area. Clinical status and potential formaldehyde sources were determined. The geometric mean formaldehyde level was 35.1 ppb and ranged from 5–132 ppb. Based on one-way ANOVA, t-tests, and linear regression, predictors of log-transformed formaldehyde concentration included absolute humidity, season, and the presence of decorative laminates, fiberglass, or permanent press fabrics (p<0.05), as well as temperature and household cleaner use (p<0.10). The geometric mean formaldehyde concentration was 57% higher in homes of children with very poorly controlled asthma compared to homes of other asthmatic children (p=0.078). This study provides a simple method for measuring household formaldehyde and suggests that exposure is related to poorly controlled asthma. PMID:23278296

Carrier Concentration Control of GaSb/GaInAsSb System

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

Lazzari, J.-L.; Anda, F. de; Nieto, J.

2007-02-22

The residual carrier concentration of GaSb and GaSb-lattice matched Ga1-xInxAsySb1-y alloys (x = 0.12-0.26; y = 0.9x) grown by liquid phase epitaxy (LPE) and molecular beam epitaxy (MBE) was studied as a function of growth temperature, V/III ratio and alloy composition. Typical carrier concentrations p {approx} 2-3x1016 cm-3 were obtained for undoped GaSb grown by MBE at 480 deg. C, by LPE from Ga-rich melt at low temperature (400 deg. C), and by LPE from Sb-rich melts at {approx}600 deg. C. The native acceptor defect responsible of the high p-type residual doping in GaSb is reduced when the indium concentrationmore » is increased, and disappears for indium rich alloys (x = 0.23, 0.26). Tellurium compensation was used for controlled n-type doping in the (0.05-30)x1017 cm-3 range. A maximum of free carrier concentration was 1.5x1018 cm-3 for LPE layers, 2x1018 cm-3 for MBE layers grown at 1.0 {mu}m/h, 3.5x1018 cm-3 for MBE layers grown at 0.2 {mu}m/h. SIMS measurements showed Te concentrations of more than 1020 at/cm3, suggesting the formation of ternary GaSb1-xTex solid solution.« less

Nonclinical dose formulation analysis method validation and sample analysis.

PubMed

Whitmire, Monica Lee; Bryan, Peter; Henry, Teresa R; Holbrook, John; Lehmann, Paul; Mollitor, Thomas; Ohorodnik, Susan; Reed, David; Wietgrefe, Holly D

2010-12-01

Nonclinical dose formulation analysis methods are used to confirm test article concentration and homogeneity in formulations and determine formulation stability in support of regulated nonclinical studies. There is currently no regulatory guidance for nonclinical dose formulation analysis method validation or sample analysis. Regulatory guidance for the validation of analytical procedures has been developed for drug product/formulation testing; however, verification of the formulation concentrations falls under the framework of GLP regulations (not GMP). The only current related regulatory guidance is the bioanalytical guidance for method validation. The fundamental parameters for bioanalysis and formulation analysis validations that overlap include: recovery, accuracy, precision, specificity, selectivity, carryover, sensitivity, and stability. Divergence in bioanalytical and drug product validations typically center around the acceptance criteria used. As the dose formulation samples are not true "unknowns", the concept of quality control samples that cover the entire range of the standard curve serving as the indication for the confidence in the data generated from the "unknown" study samples may not always be necessary. Also, the standard bioanalytical acceptance criteria may not be directly applicable, especially when the determined concentration does not match the target concentration. This paper attempts to reconcile the different practices being performed in the community and to provide recommendations of best practices and proposed acceptance criteria for nonclinical dose formulation method validation and sample analysis.

Dielectric and structural properties of aqueous nonpolar solute mixtures.

PubMed

Shvab, I; Sadus, Richard J

2012-09-28

The dielectric properties and molecular structure of water mixtures with different nonpolar solutes (methane and noble gases) are studied using molecular dynamics. The water-water, water-solute, and solute-solute interactions are calculated using the combination of a polarizable potential [J. Li, Z. Zhou, and R. J. Sadus, J. Chem. Phys. 127, 154509 (2007)] for water plus the Lennard-Jones potential. The effect of solute size and concentration on the solubility of the system, hydrogen bonding, dielectric constant, and dipole moment are investigated over a temperature range of 278-750 K and solute percentage mole fractions up to 30%. Solute particles affect the structure of water, resulting in the compression of oxygen-oxygen and oxygen-hydrogen radial distribution functions. The influence of the solute extends both to relatively low concentrations and high temperatures. The coordination numbers of aqueous solutions of the nonpolar solutes appear to be proportional to the size of the solute particles. Our study shows the destructive influence of the nonpolar solute on both the tetrahedral water structure and hydrogen bond formation at solute concentrations greater than 30%. The presence of nonpolar particles typically decreases both the dielectric constant and dipole moment. The decrease of dielectric constant and water dipole moment is directly proportional to the solute concentration and temperature.

Measurements of Peroxy Radicals and Related Species At A Rural Site During The Escompte Campaign

NASA Astrophysics Data System (ADS)

Pinceloup, S.; Laverdet, G.; Le Bras, G.

The chemical amplifier technique has been used to measure peroxy radicals (RO2) concentrations at a rural site (Dupail), located 35 km North East of Marseille, during the ESCOMPTE campaign in June-July 2001. Daily profiles of RO2 and also ozone and NOx concentrations have been recorded everyday including those of the four in- tensive observation periods (IOP). The NOx levels were most of the time lower than a few ppbv, ie characteristic of a rural site. Typical diurnal profiles of RO2 were ob- served with maxima in the range 40-180 pptv. The RO2 signals were corrected from the influence of relative humidity based on calibration of the chemical amplifier in separate laboratory experiments under controlled water vapor concentrations. Prelim- inary interpretation of the data shows very different ratios of photochemically pro- duced/transported ozone related to meteorological conditions. Further interpretation of the data is underway integrating additional measurements of a large variety of hy- drocarbons as well as some hydroperoxides and aldehydes made at the site by other groups. The results of the comparison of calculated steady state concentrations of RO2 and ozone production rate with the measured values will be presented and discussed in relation with our understanding of the tropospheric ozone production.

Levels, trends and health concerns of atmospheric PAHs in Europe

NASA Astrophysics Data System (ADS)

Garrido, Adrián; Jiménez-Guerrero, Pedro; Ratola, Nuno

2014-12-01

Changes in climate can affect the concentration patterns of polycyclic aromatic hydrocarbons (PAHs) by altering the dispersion (wind speed, mixing layer height, convective fronts), deposition by precipitation, dry deposition, photochemistry, natural emissions and background concentrations. This means the evolution trends of these pollutants have to be studied under a multi-scale perspective, allowing the establishment of transport patterns and distribution of PAHs. In this sense, this work tries to unveil the atmospheric behaviour of these pollutants using temporal data series collected in different stations from the European Monitoring and Evaluation Programme (EMEP) air sampling network. These sites are thought to avoid the direct influence of emitting areas (background stations), allowing the study of long-range transport effects, intra- and trans-annual variability, relationships between concentrations patterns and meteorological variables and latitudinal gradients of PAH levels in Europe. Overall, a typical high concentration pattern was found for the colder months (and an opposite behaviour is found for summertime). Negative trends were detected over high latitudes, for instance, in Svalbard (Norway), whereas for the United Kingdom the pattern is the inverse. Also, negative latitudinal gradients were observed in 4 of the 15 PAHs studied. Finally, air quality parameters revealed concern over human health issues, given the recent increase of BaP levels in Europe.

Evaluation of organic compounds and trace elements in Amazon Creek Basin, Oregon, September 1990

USGS Publications Warehouse

Rinella, F.A.

1993-01-01

Water and bottom sediment were collected from Amazon Creek, Oregon during a summer low-flow condition and analyzed for different classes of organic compounds, including many from the U.S. Environmental Protection Agency's priority pollutant list. Bottom sediment also was analyzed for trace elements typically associated with urban runoff. Trace-element concentrations in the less than 63 micrometer fraction of Amazon Creek bottom-sediment samples were compared with baseline concentrations (expected 95 percent confidence range) for soils from the Western United States and with concen- trations found in bottom sediment from the Willamette River Basin. Total-digestion concentrations of antimony, arsenic, cadmium, chromium, cobalt, copper, lead, manganese, mercury, nickel, silver, titanium, and zinc were enriched at some or all sites sampled. Whole-water samples from some sites contained concentrations of several chlorophenoxy-acid herbicides, the organophosphorus insecticide diazinon, and several semivolatile priority pollutants. Classes of compounds not detected in whole-water samples included carbamate insecticides, triazine and other nitrogen-containing herbicides, and purgeable organic compounds. Bottom-sediment samples contained many organochlorine compounds, including chlordane, DDT plus metabolites, dieldrin, endrin, heptachlor epoxide (a metabolite of heptachlor), and PCBs at some or all sites sampled. Twenty-four of 54 semivolatile compounds were detected in bottom- sediment samples at some or all sites sampled.

Cross-reactivity of antibodies with phenolic compounds in pistachios during quantification of ochratoxin A by commercial enzyme-linked immunosorbent assay kits.

PubMed

Lee, Hyun Jung; Meldrum, Alexander D; Rivera, Nicholas; Ryu, Dojin

2014-10-01

Ochratoxin A (OTA), a nephrotoxic mycotoxin, naturally occurs in wide range of agricultural commodities. Typical screening of OTA involves various enzyme-linked immunosorbent assay (ELISA) methods. Pistachio (Pistacia vera L.) is a rich source of phenolic compounds that may result in a false positive due to structural similarities to OTA. The present study investigated the cross-reactivity profiles of phenolic compounds using two commercial ELISA test kits. High-performance liquid chromatography was used to confirm the concentration of OTA in the pistachio samples and compared with the results obtained from ELISA. When the degree of interaction and 50 % inhibitory concentration of phenolic compounds were determined, the cross-reactivity showed a pattern similar to that observed with the commercial ELSIA kits, although quantitatively different. In addition, the degree of interaction increased with the increasing concentration of phenolic compounds. The ELISA value had stronger correlations with the content of total phenolic compound, gallic acid, and catechin (R(2) = 0.757, 0.732, and 0.729, respectively) compared with epicatechin (R(2) = 0.590). These results suggest that phenolic compounds in pistachio skins may cross-react with the OTA antibody and lead to a false positive or to an overestimation of OTA concentration in ELISA-based tests.

Emissions of Selected Semivolatile Organic Chemicals from Forest and Savannah Fires.

PubMed

Wang, Xianyu; Thai, Phong K; Mallet, Marc; Desservettaz, Maximilien; Hawker, Darryl W; Keywood, Melita; Miljevic, Branka; Paton-Walsh, Clare; Gallen, Michael; Mueller, Jochen F

2017-02-07

The emission factors (EFs) for a broad range of semivolatile organic chemicals (SVOCs) from subtropical eucalypt forest and tropical savannah fires were determined for the first time from in situ investigations. Significantly higher (t test, P < 0.01) EFs (μg kg -1 dry fuel, gas + particle-associated) for polycyclic aromatic hydrocarbons (∑ 13 PAHs) were determined from the subtropical forest fire (7,000 ± 170) compared to the tropical savannah fires (1,600 ± 110), due to the approximately 60-fold higher EFs for 3-ring PAHs from the former. EF data for many PAHs from the eucalypt forest fire were comparable with those previously reported from pine and fir forest combustion events. EFs for other SVOCs including polychlorinated biphenyl (PCB), polychlorinated naphthalene (PCN), and polybrominated diphenyl ether (PBDE) congeners as well as some pesticides (e.g., permethrin) were determined from the subtropical eucalypt forest fire. The highest concentrations of total suspended particles, PAHs, PCBs, PCNs, and PBDEs, were typically observed in the flaming phase of combustion. However, concentrations of levoglucosan and some pesticides such as permethrin peaked during the smoldering phase. Along a transect (10-150-350 m) from the forest fire, concentration decrease for PCBs during flaming was faster compared to PAHs, while levoglucosan concentrations increased.

Antibiotics in typical marine aquaculture farms surrounding Hailing Island, South China: occurrence, bioaccumulation and human dietary exposure.

PubMed

Chen, Hui; Liu, Shan; Xu, Xiang-Rong; Liu, Shuang-Shuang; Zhou, Guang-Jie; Sun, Kai-Feng; Zhao, Jian-Liang; Ying, Guang-Guo

2015-01-15

The occurrence, bioaccumulation, and human dietary exposure via seafood consumption of 37 antibiotics in six typical marine aquaculture farms surrounding Hailing Island, South China were investigated in this study. Sulfamethoxazole, salinomycin and trimethoprim were widely detected in the water samples (0.4-36.9 ng/L), while oxytetracycline was the predominant antibiotic in the water samples of shrimp larvae pond. Enrofloxacin was widely detected in the feed samples (16.6-31.8 ng/g) and erythromycin-H2O was the most frequently detected antibiotic in the sediment samples (0.8-4.8 ng/g). Erythromycin-H2O was the dominant antibiotic in the adult Fenneropenaeus penicillatus with concentrations ranging from 2498 to 15,090 ng/g. In addition, trimethoprim was found to be bioaccumulative in young Lutjanus russelli with a median bioaccumulation factor of 6488 L/kg. Based on daily intake estimation, the erythromycin-H2O in adult F. penicillatus presented a potential risk to human safety. Copyright © 2014 Elsevier Ltd. All rights reserved.

Differential sensitivity of polyhydroxyalkanoate producing bacteria to fermentation inhibitors and comparison of polyhydroxybutyrate production from Burkholderia cepacia and Pseudomonas pseudoflava.

PubMed

Dietrich, Diane; Illman, Barbara; Crooks, Casey

2013-06-04

The aim of this study is determine the relative sensitivity of a panel of seven polyhydroxyalkanoate producing bacteria to a panel of seven lignocellulosic-derived fermentation inhibitors representing aliphatic acids, furans and phenolics. A further aim was to measure the polyhydroxybutyrate production of select organisms on lignocellulosic-derived monosaccharides arabinose, xylose, glucose and mannose. We examined the sensitivity of seven polyhydroxyalkanoate producing bacteria: Azohydromonas lata, Bacillus megaterium, Bacillus cereus, Burkholderia cepacia, Pseudomonas olevorans, Pseudomonas pseudoflava and Ralstonia eutropha, against seven fermentation inhibitors produced by the saccharification of lignocellulose: acetic acid, levulinic acid, coumaric acid, ferulic acid, syringaldehyde, furfural, and hyroxymethyfurfural. There was significant variation in the sensitivity of these microbes to representative phenolics ranging from 0.25-1.5 g/L coumaric and ferulic acid and between 0.5-6.0 g/L syringaldehyde. Inhibition ranged from 0.37-4 g/L and 0.75-6 g/L with acetic acid and levulinic acid, respectively. B. cepacia and P. pseudoflava were selected for further analysis of polyhydroxyalkanoate production. We find significant differences in sensitivity to the fermentation inhibitors tested and find these variations to be over a relevant concentration range given the concentrations of inhibitors typically found in lignocellulosic hydrolysates. Of the seven bacteria tested, B. cepacia demonstrated the greatest inhibitor tolerance. Similarly, of two organisms examined for polyhydroxybutyrate production, B. cepacia was notably more efficient when fermenting pentose substrates.

Differential sensitivity of polyhydroxyalkanoate producing bacteria to fermentation inhibitors and comparison of polyhydroxybutyrate production from Burkholderia cepacia and Pseudomonas pseudoflava

PubMed Central

2013-01-01

Background The aim of this study is determine the relative sensitivity of a panel of seven polyhydroxyalkanoate producing bacteria to a panel of seven lignocellulosic-derived fermentation inhibitors representing aliphatic acids, furans and phenolics. A further aim was to measure the polyhydroxybutyrate production of select organisms on lignocellulosic-derived monosaccharides arabinose, xylose, glucose and mannose. Findings We examined the sensitivity of seven polyhydroxyalkanoate producing bacteria: Azohydromonas lata, Bacillus megaterium, Bacillus cereus, Burkholderia cepacia, Pseudomonas olevorans, Pseudomonas pseudoflava and Ralstonia eutropha, against seven fermentation inhibitors produced by the saccharification of lignocellulose: acetic acid, levulinic acid, coumaric acid, ferulic acid, syringaldehyde, furfural, and hyroxymethyfurfural. There was significant variation in the sensitivity of these microbes to representative phenolics ranging from 0.25-1.5 g/L coumaric and ferulic acid and between 0.5-6.0 g/L syringaldehyde. Inhibition ranged from 0.37-4 g/L and 0.75-6 g/L with acetic acid and levulinic acid, respectively. B. cepacia and P. pseudoflava were selected for further analysis of polyhydroxyalkanoate production. Conclusions We find significant differences in sensitivity to the fermentation inhibitors tested and find these variations to be over a relevant concentration range given the concentrations of inhibitors typically found in lignocellulosic hydrolysates. Of the seven bacteria tested, B. cepacia demonstrated the greatest inhibitor tolerance. Similarly, of two organisms examined for polyhydroxybutyrate production, B. cepacia was notably more efficient when fermenting pentose substrates. PMID:23734728

Seeing the light: the effects of particles, dissolved materials, and temperature on in situ measurements of DOM fluorescence in rivers and streams

USGS Publications Warehouse

Downing, Bryan D.; Pellerin, Brian A.; Bergamaschi, Brian A.; Saraceno, John Franco; Kraus, Tamara E.C.

2012-01-01

Field-deployable sensors designed to continuously measure the fluorescence of colored dissolved organic matter (FDOM) in situ are of growing interest. However, the ability to make FDOM measurements that are comparable across sites and over time requires a clear understanding of how instrument characteristics and environmental conditions affect the measurements. In particular, the effects of water temperature and light attenuation by both colored dissolved material and suspended particles may be significant in settings such as rivers and streams. Using natural standard reference materials, we characterized the performance of four commercially-available FDOM sensors under controlled laboratory conditions over ranges of temperature, dissolved organic matter (DOM) concentrations, and turbidity that spanned typical environmental ranges. We also examined field data from several major rivers to assess how often attenuation artifacts or temperature effects might be important. We found that raw (uncorrected) FDOM values were strongly affected by the light attenuation that results from dissolved substances and suspended particles as well as by water temperature. Observed effects of light attenuation and temperature agreed well with theory. Our results show that correction of measured FDOM values to account for these effects is necessary and feasible over much of the range of temperature, DOM concentration, and turbidity commonly encountered in surface waters. In most cases, collecting high-quality FDOM measurements that are comparable through time and between sites will require concurrent measurements of temperature and turbidity, and periodic discrete sample collection for laboratory measurement of DOM.

Effects of Atmospheric Water and Surface Wind on Passive Microwave Retrievals of Sea Ice Concentration: a Simulation Study

NASA Astrophysics Data System (ADS)

Shin, D.; Chiu, L. S.; Clemente-Colon, P.

2006-05-01

The atmospheric effects on the retrieval of sea ice concentration from passive microwave sensors are examined using simulated data typical for the Arctic summer. The simulation includes atmospheric contributions of cloud liquid water, water vapor and surface wind on the microwave signatures. A plane parallel radiative transfer model is used to compute brightness temperatures at SSM/I frequencies over surfaces that contain open water, first-year (FY) ice and multi-year (MY) ice and their combinations. Synthetic retrievals in this study use the NASA Team (NT) algorithm for the estimation of sea ice concentrations. This study shows that if the satellite sensor's field of view is filled with only FY ice the retrieval is not much affected by the atmospheric conditions due to the high contrast between emission signals from FY ice surface and the signals from the atmosphere. Pure MY ice concentration is generally underestimated due to the low MY ice surface emissivity that results in the enhancement of emission signals from the atmospheric parameters. Simulation results in marginal ice areas also show that the atmospheric effects from cloud liquid water, water vapor and surface wind tend to degrade the accuracy at low sea ice concentration. FY ice concentration is overestimated and MY ice concentration is underestimated in the presence of atmospheric water and surface wind at low ice concentration. This compensating effect reduces the retrieval uncertainties of total (FY and MY) ice concentration. Over marginal ice zones, our results suggest that strong surface wind is more important than atmospheric water in contributing to the retrieval errors of total ice concentrations in the normal ranges of these variables.

Diagnostic Imaging in Flames with Instantaneous Planar Coherent Raman Spectroscopy.

PubMed

Bohlin, A; Kliewer, C J

2014-04-03

Spatial mapping of temperature and molecular species concentrations is vitally important in studies of gaseous chemically reacting flows. Temperature marks the evolution of heat release and energy transfer, while species concentration gradients provide critical information on mixing and chemical reaction. Coherent anti-Stokes Raman spectroscopy (CARS) was pioneered in measurements of such processes almost 40 years ago and is authoritative in terms of the accuracy and precision it may provide. While a reacting flow is fully characterized in three-dimensional space, a limitation of CARS has been its applicability as a point-wise measurement technique, motivating advancement toward CARS imaging, and attempts have been made considering one-dimensional probing. Here, we report development of two-dimensional CARS, with the first diagnostics of a planar field in a combusting flow within a single laser pulse, resulting in measured isotherms ranging from 450 K up to typical hydrocarbon flame temperatures of about 2000 K with chemical mapping of O2 and N2.

Evaluation of metal content in perch of the Ob River basin

NASA Astrophysics Data System (ADS)

Osipova, N. A.; Stepanova, K. D.; Matveenko, I. A.

2015-11-01

The geochemical features of river perch in the River Ob basin have been studied (the upper and middle reaches of the Ob River and the lower reach of the Tom River). The contents of Ag, Bi, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sn, W, Zn, Hg in perch's soft tissue are defined by the methods of ICP AES and stripping voltammetry, that of mercury in bones - by the atomic absorption method using mercury analyzer PA-915+. The distribution series of metal absolute concentrations in perch's soft tissue from the Ob River basin are plotted: Fe > Zn > Cu > Mn, typical for uncontaminated or slightly metal contaminated water bodies. In soft tissue of the studied samples the metal content does not exceed the permissible values. The mercury content in bones of studied samples is in the range 0,036-0,556 mg/kg. The mercury concentration is higher in bones in comparison with soft tissue in all samples.

Silica formation with nanofiber morphology via helical display of the silaffin R5 peptide on a filamentous bacteriophage.

PubMed

Song, In-Wong; Park, Hyojung; Park, Jung Han; Kim, Hyunook; Kim, Seong Hun; Yi, Sung; Jaworski, Justyn; Sang, Byoung-In

2017-11-24

Biological systems often generate unique and useful structures, which can have industrial relevance either as direct components or as an inspiration for biomimetic materials. For fabrication of nanoscale silica structures, we explored the use of the silaffin R5 peptide from Cylindrotheca fusiformis expressed on the surface of the fd bacteriophage. By utilizing the biomineralizing peptide component displayed on the bacteriophage surface, we found that low concentrations (0.09 mg/mL of the R5 bacteriophage, below the concentration range used in other studies) could be used to create silica nanofibers. An additional benefit of this approach is the ability of our R5-displaying phage to form silica materials without the need for supplementary components, such as aminopropyl triethoxysilane, that are typically used in such processes. Because this method for silica formation can occur under mild conditions when implementing our R5 displaying phage system, we may provide a relatively simple, economical, and environmentally friendly process for creating silica nanomaterials.

Exposure history of the lunar meteorite, Elephant Moraine 87521

NASA Technical Reports Server (NTRS)

Vogt, S.; Herzog, G. F.; Eugster, O.; Michel, TH.; Niedermann, S.; Kraehenbuhl, U.; Middleton, R.; Dezfouly-Arjomandy, B.; Fink, D.; Klein, J.

1993-01-01

We report the noble gas concentrations and the Al-26, Be-10, Cl-36, and Ca-41 activities of the Antarctic lunar meteorite Elephant Moraine 87521. Although the actual exposure history of the meteorite may have been more complex, the following model history accounts satisfactorily for the cosmogenic nuclide data: A first stage of lunar irradiation for about 1 Ma at a depth of 1-5 g/sq cm followed, not necessarily directly, by a second one for 26 Ma at about 565 g/sq cm; launch from the moon less than 0.1 Ma ago; and arrival on earth 15-50 ka ago. The small concentration of trapped gases shows that except for some material that may have been introduced at the moment of launch, EET 87521 spent less than 1 Ma at a lunar depth less than 1 g/sq cm. EET 87521 has a K/Ar age in the range 3.0-3.4 Ga, which is typical for lunar mare basalts.

The reduction of HNO3 by volatile organic compounds emitted by motor vehicles

NASA Astrophysics Data System (ADS)

Rutter, A. P.; Malloy, Q. G. J.; Leong, Y. J.; Gutierrez, C. V.; Calzada, M.; Scheuer, E.; Dibb, J. E.; Griffin, R. J.

2014-04-01

Nitric acid (HNO3) was reduced in a flow tube by volatile organic carbon compounds (VOCs) generated from engine oil vapor. The primary reaction product was believed to be HONO. The reaction was not enhanced when Teflon® Raschig rings were added to the flow tube to increase surface area, thereby showing the reaction to be homogeneous under the conditions studied. The HONO formation observed ranged between 0.1 and 0.6 ppb h-1, with a mean of 0.3 ± 0.1 ppb h-1, for typical HNO3 concentrations of 4-5 ppb and estimated concentrations of the reactive components in the engine oil vapor between 200 and 300 ppt. The observations in this study compare well to a recently published field study conducted in Houston that observed average formation rates of 0.6 ± 0.3 ppb h-1. Water vapor was found to decrease the HONO formation rate by ˜0.1 ppb h-1 for every 1% increase in the water mixing ratio.

Biomonitoring of trace metal bioavailabilities to the barnacle Amphibalanus amphitrite along the Iranian coast of the Persian Gulf.

PubMed

Nasrolahi, A; Smith, B D; Ehsanpour, M; Afkhami, M; Rainbow, P S

2014-10-01

The fouling barnacle Amphibalanus amphitrite is a cosmopolitan biomonitor of trace metal bioavailabilities, with an international comparative data set of body metal concentrations. Bioavailabilities of As, Cd, Cr, Cu, Fe, Mn, Pb, V and Zn to A. amphitrite were investigated at 19 sites along the Iranian coast of the understudied Persian Gulf. Commercial and fishing ports showed extremely high Cu bioavailabilities, associated with high Zn bioavailabilities, possibly from antifouling paints and procedures. V availability was raised at one port, perhaps associated with fuel leakage. Cd bioavailabilities were raised at sites near the Strait of Hormuz, perhaps affected by adjacent upwelling off Oman. The As data allow a reinterpretation of the typical range of accumulated As concentrations in A. amphitrite. The Persian Gulf data add a new region to the A. amphitrite database, confirming its importance in assessing the ecotoxicologically significant trace metal contamination of coastal waters across the world. Copyright © 2014 Elsevier Ltd. All rights reserved.

Dextromethorphan abuse leading to assault, suicide, or homicide.

PubMed

Logan, Barry K; Yeakel, Jillian K; Goldfogel, Gary; Frost, Michael P; Sandstrom, Greg; Wickham, Dennis J

2012-09-01

Dextromethorphan is a commonly encountered antitussive medication which has found additional therapeutic use in the treatment of pseudobulbar disorder and as an adjunct to opiate use in pain management. Dextromethorphan at high doses has phencyclidine-like effects on the NMDA receptor system; recreational use of high doses has been found to cause mania and hallucinations. The toxicology and pharmacology of the drug in abuse are reviewed, and the historical literature of adverse psychiatric outcomes is assessed. Five new cases of dextromethorphan intoxication that resulted in assault, suicide, and homicide are reported, together with the corresponding toxicology results. Blood concentrations ranged from 300 to 19,000 μg/L. These results are compared with typical concentrations reported in therapeutic use and impaired driving cases. Based on these findings, dextromethorphan should be considered as a potential causative agent in subjects presenting with mania, psychosis, or hallucinations, and abusers are at risk for violent and self-destructive acts. © 2012 American Academy of Forensic Sciences.

Towards environmental management of water turbidity within open coastal waters of the Great Barrier Reef.

PubMed

Macdonald, Rachael K; Ridd, Peter V; Whinney, James C; Larcombe, Piers; Neil, David T

2013-09-15

Water turbidity and suspended sediment concentration (SSC) are commonly used as part of marine monitoring and water quality plans. Current management plans utilise threshold SSC values derived from mean-annual turbidity concentrations. Little published work documents typical ranges of turbidity for reefs within open coastal waters. Here, time-series turbidity measurements from 61 sites in the Great Barrier Reef (GBR) and Moreton Bay, Australia, are presented as turbidity exceedance curves and derivatives. This contributes to the understanding of turbidity and SSC in the context of environmental management in open-coastal reef environments. Exceedance results indicate strong spatial and temporal variability in water turbidity across inter/intraregional scales. The highest turbidity across 61 sites, at 50% exceedance (T50) is 15.3 NTU and at 90% exceedance (T90) 4.1 NTU. Mean/median turbidity comparisons show strong differences between the two, consistent with a strongly skewed turbidity regime. Results may contribute towards promoting refinement of water quality management protocols. Copyright © 2013 Elsevier Ltd. All rights reserved.

Decoding the Nonvolatile Sensometabolome of Orange Juice ( Citrus sinensis).

PubMed

Glabasnia, Anneke; Dunkel, Andreas; Frank, Oliver; Hofmann, Thomas

2018-03-14

Activity-guided fractionation in combination with the taste dilution analysis, followed by liquid chromatography-tandem mass spectrometry and nuclear magnetic resonance experiments, led to the identification of 10 polymethoxylated flavones (PMFs), 6 limonoid glucosides, and 2 limonoid aglycones as the key bitterns of orange juice. Quantitative studies and calculation of dose-over-threshold factors, followed by taste re-engineering, demonstrated for the first time 25 sensometabolites to be sufficient to reconstruct the typical taste profile of orange juices and indicated that not a single compound can be considered a suitable marker for juice bitterness. Intriguingly, the taste percept of orange juice seems to be created by a rather complex interplay of limonin, limonoid glucosides, PMFs, organic acids, and sugars. For the first time, sub-threshold concentrations of PMFs were shown to enhance the perceived bitterness of limonoids. Moreover, the influence of sugars on the perceived bitterness of limonoids and PMFs in orange juice relevant concentration ranges was quantitatively elucidated.

Radon exhalation rates from building materials using electret ion chamber radon monitors in accumulators.

PubMed

Kotrappa, Payasada; Stieff, Frederick

2009-08-01

An electret ion chamber (EIC) radon monitor in a sealed accumulator measures the integrated average radon concentration at the end of the accumulation duration. Theoretical equations have been derived to relate such radon concentrations (Bq m(-3) ) to the radon emanation rate (Bq d(-1)) from building materials enclosed in the accumulator. As an illustration, a 4-L sealable glass jar has been used as an accumulator to calculate the radon emanation rate from different granite samples. The radon emanation rate was converted into radon flux (Bq mm(-2) d(-1)) by dividing the emanation rate by surface area of the sample. Fluxes measured on typical, commercially available granites ranged from 20-30 Bq m(-2) d(-1). These results are similar to the results reported in the literature. The lower limit of detection for a 2-d measurement works out to be 7 Bq m(-2) d(-1). Equations derived can also be used for other sealable accumulators and other integrating detectors, such as alpha track detectors.

Uptake and Accumulation of Pharmaceuticals in Overhead- and Surface-Irrigated Greenhouse Lettuce.

PubMed

Bhalsod, Gemini D; Chuang, Ya-Hui; Jeon, Sangho; Gui, Wenjun; Li, Hui; Ryser, Elliot T; Guber, Andrey K; Zhang, Wei

2018-01-31

Understanding the uptake and accumulation of pharmaceuticals in vegetables under typical irrigation practices is critical to risk assessment of crop irrigation with reclaimed water. This study investigated the pharmaceutical residues in greenhouse lettuce under overhead and soil-surface irrigations using pharmaceutical-contaminated water. Compared to soil-surface irrigation, overhead irrigation substantially increased the pharmaceutical residues in lettuce shoots. The increased residue levels persisted even after washing for trimethoprim, monensin sodium, and tylosin, indicating their strong sorption to the shoots. The postwashing concentrations in fresh shoots varied from 0.05 ± 0.04 μg/kg for sulfadiazine to 345 ± 139 μg/kg for carbamazepine. Root concentration factors ranged from 0.04 ± 0.14 for tylosin to 19.2 ± 15.7 for sulfamethoxazole. Translocation factors in surface-irrigated lettuce were low for sulfamethoxalzole, trimethoprim, monensin sodium, and tylosin (0.07-0.15), but high for caffeine (4.28 ± 3.01) and carbamazepine (8.15 ± 2.87). Carbamazepine was persistent in soil and hyperaccumulated in shoots.

Hydrologic data summary for the St. Lucie River Estuary, Martin and St. Lucie Counties, Florida, 1998-2001

USGS Publications Warehouse

Byrne, Michael J.; Patino, Eduardo

2004-01-01

A hydrologic analysis was made at three canal sites and four tidal sites along the St. Lucie River Estuary in southeastern Florida from 1998 to 2001. The data included for analysis are stage, 15-minute flow, salinity, water temperature, turbidity, and suspended-solids concentration. During the period of record, the estuary experienced a drought, major storm events, and high-water discharge from Lake Okeechobee. Flow mainly occurred through the South Fork of the St. Lucie River; however, when flow increased through control structures along the C-23 and C-24 Canals, the North Fork was a larger than usual contributor of total freshwater inflow to the estuary. At one tidal site (Steele Point), the majority of flow was southward toward the St. Lucie Inlet; at a second tidal site (Indian River Bridge), the majority of flow was northward into the Indian River Lagoon. Large-volume stormwater discharge events greatly affected the St. Lucie River Estuary. Increased discharge typically was accompanied by salinity decreases that resulted in water becoming and remaining fresh throughout the estuary until the discharge events ended. Salinity in the estuary usually returned to prestorm levels within a few days after the events. Turbidity decreased and salinity began to increase almost immediately when the gates at the control structures closed. Salinity ranged from less than 1 to greater than 35 parts per thousand during the period of record (1998-2001), and typically varied by several parts per thousand during a tidal cycle. Suspended-solids concentrations were observed at one canal site (S-80) and two tidal sites (Speedy Point and Steele Point) during a discharge event in April and May 2000. Results suggest that most deposition of suspended-solids concentration occurs between S-80 and Speedy Point. The turbidity data collected also support this interpretation. The ratio of inorganic to organic suspended-solids concentration observed at S-80, Speedy Point, and Steele Point during the discharge event indicates that most flocculation of suspended-solids concentration occurs between Speedy Point and Steele Point.

Population pharmacokinetics of unbound hydrocortisone in critically ill neonates and infants with vasopressor-resistant hypotension.

PubMed

Vezina, Heather E; Ng, Chee M; Vazquez, Delia M; Barks, John D; Bhatt-Mehta, Varsha

2014-07-01

To determine the population pharmacokinetics of unbound hydrocortisone in critically ill neonates and infants receiving IV hydrocortisone for treatment of vasopressor-resistant hypotension and to identify patient-specific sources of pharmacokinetic variability. Prospective observational cohort study. Level 3 neonatal ICU. Sixty-two critically ill neonates and infants receiving IV hydrocortisone as part of standard of care for the treatment of vasopressor-resistant hypotension: median gestational age 28 weeks (range, 23-41), median weight 1.2 kg (range, 0.5-4.4), and 29 females. None. Unbound baseline cortisol and postdose hydrocortisone concentrations measured from blood samples being drawn for routine laboratory tests. A one-compartment model best described the data. Allometric weight and postmenstrual age were significant covariates on unbound hydrocortisone clearance and volume of distribution. Final population estimates for clearance, volume of distribution, and baseline cortisol concentration were 20.2 L/hr, 244 L, and 1.37 ng/mL, respectively. Using the median weight and postmenstrual age of our subjects (i.e., 1.2 kg and 28 wk) in the final model, the typical unbound hydrocortisone clearance and volume of distribution were 1.0 L/hr and 4.2 L, respectively. The typical half-life for unbound hydrocortisone was 2.9 hours. A sharp and continuous increase in unbound hydrocortisone clearance was observed at 35 weeks postmenstrual age. We report the first pharmacokinetic data for unbound hydrocortisone, the pharmacologically active moiety, in critically ill neonates and infants with vasopressor-resistant hypotension. Unbound hydrocortisone clearance increased with body weight and was faster in children with an older postmenstrual age. Unbound hydrocortisone clearance increased sharply at 35 weeks postmenstrual age and continued to mature thereafter. This study lays the groundwork for evaluating unbound hydrocortisone exposure-response relationships and drawing definitive conclusions about the dosing of IV hydrocortisone in critically ill neonates and infants with vasopressor-resistant hypotension.

Population pharmacokinetics of unbound hydrocortisone in critically ill neonates and infants with vasopressor-resistant hypotension

PubMed Central

Vezina, Heather E.; Ng, Chee M.; Vazquez, Delia M.; Barks, John D.; Bhatt-Mehta, Varsha

2014-01-01

Objective To determine the population pharmacokinetics of unbound hydrocortisone (HC) in critically ill neonates and infants receiving intravenous HC for treatment of vasopressor-resistant hypotension and to identify patient-specific sources of pharmacokinetic variability. Design Prospective observational cohort study. Setting Level 3 neonatal intensive care unit. Patients Sixty-two critically ill neonates and infants receiving intravenous HC as part of standard of care for the treatment of vasopressor-resistant hypotension: median gestational age 28 weeks (range, 23 to 41), median weight 1.2 kg (range, 0.5 to 4.4), 29 females. Interventions None. Measurements Unbound baseline cortisol and post-dose HC concentrations measured from blood samples being drawn for routine laboratory tests. Main Results A one compartment model best described the data. Allometric weight and postmenstrual age (PMA) were significant covariates on unbound HC clearance (CL) and volume of distribution (V). Final population estimates for CL, V, and baseline cortisol concentration were 20.2 L/h, 244 L, and 1.37 ng/mL, respectively. Using the median weight and PMA of our subjects (i.e. 1.2 kg and 28 weeks) in the final model, the typical unbound HC CL and V were 1.0 L/h and 4.2 L, respectively. The typical half-life for unbound HC was 2.9 hours. A sharp and continuous increase in unbound HC CL was observed at 35 weeks PMA. Conclusions We report the first pharmacokinetic data for unbound HC, the pharmacologically active moiety, in critically ill neonates and infants with vasopressor-resistant hypotension. Unbound HC CL increased with body weight and was faster in children with an older PMA. Unbound HC CL increased sharply at 35 weeks PMA and continued to mature thereafter. This study lays the groundwork for evaluating unbound HC exposure-response relationships and drawing definitive conclusions about the dosing of intravenous HC in critically-ill neonates and infants with vasopressor-resistant hypotension. PMID:24797719

Monitoring urban impacts on suspended sediment, trace element, and nutrient fluxes within the City of Atlanta, Georgia, USA: Program design, methodological considerations, and initial results

USGS Publications Warehouse

Horowitz, A.J.; Elrick, K.A.; Smith, J.J.

2008-01-01

Atlanta, Georgia (City of Atlanta, COA), is one of the most rapidly growing urban areas in the US. Beginning in 2003, the US Geological Survey established a long-term water-quantity/quality monitoring network for the COA. The results obtained during the first 2 years have provided insights into the requirements needed to determine the extent of urban impacts on water quality, especially in terms of estimating the annual fluxes of suspended sediment, trace/major elements, and nutrients. During 2004/2005, suspended sediment fluxes from the City of Atlanta (COA) amounted to about 150 000 t year-1; ??? 94% of the transport occurred in conjunction with storm-flow, which also accounted for ??? 65% of the annual discharge. Typically, storm-flow averaged ??? 20% of theyear. Normally, annual suspended sediment fluxes are determined by summing daily loads based on a single calculation step using mean-daily discharge and a single rating curve-derived suspended sediment concentration. Due to the small and 'flashy' nature of the COAs streams, this approach could produce underestimates ranging from 25% to 64%. Accurate estimates (?? 15%) require calculation time-steps as short as every 2-3 h. Based on annual median base-flow/storm-flow chemical concentrations, the annual fluxes of ??? 75% of trace elements (e.g. Cu, Pb, Zn), major elements (e.g. Fe, Al), and total P occur in association with suspended sediment; in turn, ??? 90% of the transport of these constituents occur in conjunction with storm-flow. As such, base-flow sediment-associated and dissolved contributions represent relatively insignificant portions of the total annual load. An exception is total N, whose sediment-associated fluxes range from 50% to 60%; even so, storm-related transport typically exceeds 80%. Hence, in urban environments, non-point-source appear to be the dominant contributors to the fluxes of these constituents.

Headspace-SPME-GC/MS as a simple cleanup tool for sensitive 2,6-diisopropylphenol analysis from lipid emulsions and adaptable to other matrices.

PubMed

Pickl, Karin E; Adamek, Viktor; Gorges, Roland; Sinner, Frank M

2011-07-15

Due to increased regulatory requirements, the interaction of active pharmaceutical ingredients with various surfaces and solutions during production and storage is gaining interest in the pharmaceutical research field, in particular with respect to development of new formulations, new packaging material and the evaluation of cleaning processes. Experimental adsorption/absorption studies as well as the study of cleaning processes require sophisticated analytical methods with high sensitivity for the drug of interest. In the case of 2,6-diisopropylphenol - a small lipophilic drug which is typically formulated as lipid emulsion for intravenous injection - a highly sensitive method in the concentration range of μg/l suitable to be applied to a variety of different sample matrices including lipid emulsions is needed. We hereby present a headspace-solid phase microextraction (HS-SPME) approach as a simple cleanup procedure for sensitive 2,6-diisopropylphenol quantification from diverse matrices choosing a lipid emulsion as the most challenging matrix with regard to complexity. By combining the simple and straight forward HS-SPME sample pretreatment with an optimized GC-MS quantification method a robust and sensitive method for 2,6-diisopropylphenol was developed. This method shows excellent sensitivity in the low μg/l concentration range (5-200μg/l), good accuracy (94.8-98.8%) and precision (intraday-precision 0.1-9.2%, inter-day precision 2.0-7.7%). The method can be easily adapted to other, less complex, matrices such as water or swab extracts. Hence, the presented method holds the potential to serve as a single and simple analytical procedure for 2,6-diisopropylphenol analysis in various types of samples such as required in, e.g. adsorption/absorption studies which typically deal with a variety of different surfaces (steel, plastic, glass, etc.) and solutions/matrices including lipid emulsions. Copyright © 2011 Elsevier B.V. All rights reserved.

Extension of fourier transform vibrational circular dichroism into the near-infrared region: continuous spectral coverage from 800 to 10 000 cm(-1).

PubMed

Cao, Xiaolin; Shah, Rekha D; Dukor, Rina K; Guo, Changning; Freedman, Teresa B; Nafie, Laurence A

2004-09-01

We report the first vibrational circular dichroism (VCD) spectra with continuous coverage from 800 cm(-1) in the mid-infrared (MIR) region to 10 000 cm(-1) in the near-infrared (NIR) region. This coverage is illustrated with MIR and NIR absorbance and VCD spectra of 2,2-dimethyl-dioxolane-4-methanol (DDM), alpha-pinene, and camphor that serve as calibration samples over this entire region. Commercially available, dual-source Fourier transform (FT) MIR and NIR VCD spectrometers were equipped with appropriate light sources, optics, and detectors, and were modified for dual-polarization-modulation (DPM) operation. The combination of liquid-nitrogen- and thermoelectric-cooled HgCdTe (MCT) detectors, as well as InGaAs and Germanium (Ge) detectors operating at room temperature, permitted collection of the desired absorbance and VCD spectra across the range of vibrational fundamental, combination band, and overtone frequencies. The spectra of DDM and alpha-pinene were measured as neat liquids and recorded for both enantiomers in the various spectral regions. Spectra for camphor were all measured in CCl(4) solution at a concentration of 0.6 M, except for the carbonyl-stretching region, where a more dilute concentration was used. The typical anisotropy ratios (g) of the three molecules were estimated with respect to their strongest VCD bands in each spectral region. It was found that for all three molecules in the spectral regions above 2000 cm(-1), anisotropy ratios are approximately the same order (10(-5)) of magnitude. However, in the MIR region, the typical anisotropy ratios are significantly different for the three molecules. This study demonstrates that with modern FT-VCD spectrometers modified for DPM operation, VCD spectra can be measured continuously across a wide spectral range from the MIR to nearly the visible region with an unsurpassed combination of signal-to-noise ratio and spectral resolution.

Screening for Groundwater Contaminants Discharging to Urban Streams

NASA Astrophysics Data System (ADS)

Roy, J. W.; Bickerton, G.; Voralek, J.

2009-05-01

Groundwater contaminated with urban pollutants can adversely affect freshwater aquatic ecosystems where it discharges to streams, lakes or wetlands. Generally such occurrences have been revealed following the discovery of contaminated groundwater plumes at a particular site or from wells in the area. Thus, this contaminant pathway tends to be dealt with on a site-specific and aquifer-focused basis. In contrast, surface water contaminant monitoring typically relies on bulk water concentrations from one or a small set of locations, thus ignoring the spatial variation in contaminant loading, potential losses to sediment or the atmosphere, and the full range of benthic components of the aquatic ecosystem. There are few studies outlining the extent of this contamination from the perspective of the surface water body's deeper benthic community, which might be expected to experience the greatest contaminant concentrations, on more than a local-scale. In this study, we report on an approach to stream-reach-screening for urban contaminants in discharging groundwater, with the focus on detection rather than accurate quantification. The methodology consists of a drive-point technique for sampling groundwater from below the stream bed (e.g. typically 50 cm) along a chosen reach at intervals of about 10 m. Groundwater samples were then analyzed for a wide range of common urban contaminants and general chemistry. This screening method was performed in three urban settings in Canada with known groundwater contamination, covering sections of about 140 to >500 m. The known contaminant plumes at each site were detected and roughly delineated. In addition, potential areas of previously-unknown groundwater contamination were also identified at each site. Contaminants included BTEX and other petroleum hydrocarbons, various chlorinated solvent compounds, nitrate, 1,4-dioxane, MTBE and elevated chloride (likely indicating road salt). These preliminary findings suggest that this approach may be useful for quickly assessing the cumulative threat to aquatic ecosystems of potentially multiple groundwater contaminant sources discharging to surface water bodies in urban settings.

Kinetics of Deliquescence

NASA Astrophysics Data System (ADS)

McGraw, R. L.; Lewis, E.

2009-12-01

We examine deliquescence phase transformation for inorganic salt particles ranging from bulk down to several nanometers in size. Thermodynamic properties of the particles, coated with aqueous solution layers of varying thickness and surrounded by vapor, are analyzed. A thin layer criterion is introduced to define a limiting deliquescence relative humidity (DRH). Nano-size particles are predicted to deliquesce at relative humidity just below the DRH on crossing a nucleation barrier, located at a critical solution layer thickness. This barrier vanishes precisely at the DRH defined by the criterion. For a population of particles, the inherent random nature of the nucleation process is predicted to result in a distribution of RH values over which deliquescence will be seen to occur. Measurement of this (apparent) non-abrupt deliquescence of the population should provide both a validation of the nucleation mechanism and a quantitative determination of nucleation rate. This paper presents calculations of crossing (i.e. deliquescence) rate using the theory of mean first passage times (MFPT). MFPT theory is shown to provide a generalization of Becker-Döring nucleation kinetics especially useful for barrier heights much lower than those typically encountered in vapor-liquid nucleation. Barrier heights for deliquescence depend on the concentration of pre-deliquesced particles and observation time, but are typically in the 5-15kT range. Calculations use the tandem nano-differential mobility analyzer setup of Biskos et al. [1] as a model framework. In their experiment, a concentration of dry salt particles is subject to a higher RH for some observation time, after which is measured the (well-separated) populations of un-deliquesced particles and those that have deliquesced. Theoretical estimates for the conversion kinetics are presented as a function of dry particle size, DRH, and salt properties. [1] G. Biskos, A. Malinowski, L. M. Russell, P. R. Buseck, and S. T. Martin, Aerosol Sci. and Technol. 40, 97 (2006).

Impacts of stormwater runoff in the Southern California Bight: Relationships among plume constituents

USGS Publications Warehouse

Reifel, K.M.; Johnson, S.C.; DiGiacomo, P.M.; Mengel, M.J.; Nezlin, N.P.; Warrick, J.A.; Jones, B.H.

2009-01-01

The effects from two winter rain storms on the coastal ocean of the Southern California Bight were examined as part of the Bight '03 program during February 2004 and February-March 2005. The impacts of stormwater from fecal indicator bacteria, water column toxicity, and nutrients were evaluated for five major river discharges: the Santa Clara River, Ballona Creek, the San Pedro Shelf (including the Los Angeles, San Gabriel, and Santa Ana Rivers), the San Diego River, and the Tijuana River. Exceedances of bacterial standards were observed in most of the systems. However, the areas of impact were generally spatially limited, and contaminant concentrations decreased below California Ocean Plan standards typically within 2-3 days. The largest bacterial concentrations occurred in the Tijuana River system where exceedances of fecal indicator bacteria were noted well away from the river mouth. Maximum nitrate concentrations (~40 ??M) occurred in the San Pedro Shelf region near the mouth of the Los Angeles River. Based on the results of general linear models, individual sources of stormwater differ in both nutrient concentrations and the concentration and composition of fecal indicator bacteria. While nutrients appeared to decrease in plume waters due to simple mixing and dilution, the concentration of fecal indicator bacteria in plumes depends on more than loading and dilution rates. The relationships between contaminants (nutrients and fecal indicator bacteria) and plume indicators (salinity and total suspended solids) were not strong indicating the presence of other potentially important sources and/or sinks of both nutrients and fecal indicator bacteria. California Ocean Plan standards were often exceeded in waters containing greater than 10% stormwater (<28-30 salinity range). The median concentration dropped below the standard in the 32-33 salinity range (1-4% stormwater) for total coliforms and Enterococcus spp. and in the 28-30 salinity range (10-16% stormwater) for fecal coliforms. Nutrients showed a similar pattern with the highest median concentrations in water with greater than 10% stormwater. Relationships between colored dissolved organic matter (CDOM) and salinity and between total suspended solids and beam attenuation indicate that readily measurable, optically active variables can be used as proxies to provide at least a qualitative, if not quantitative, evaluation of the distribution of the dissolved, as well as the particulate, components of stormwater plumes. In this context, both CDOM absorption and the beam attenuation coefficient can be derived from satellite ocean color measurements of inherent optical properties suggesting that remote sensing of ocean color should be useful in mapping the spatial areas and durations of impacts from these contaminants. ?? 2009 Elsevier Ltd.

Impacts of stormwater runoff in the Southern California Bight: Relationships among plume constituents

NASA Astrophysics Data System (ADS)

Reifel, Kristen M.; Johnson, Scott C.; DiGiacomo, Paul M.; Mengel, Michael J.; Nezlin, Nikolay P.; Warrick, Jonathan A.; Jones, Burton H.

2009-08-01

The effects from two winter rain storms on the coastal ocean of the Southern California Bight were examined as part of the Bight '03 program during February 2004 and February-March 2005. The impacts of stormwater from fecal indicator bacteria, water column toxicity, and nutrients were evaluated for five major river discharges: the Santa Clara River, Ballona Creek, the San Pedro Shelf (including the Los Angeles, San Gabriel, and Santa Ana Rivers), the San Diego River, and the Tijuana River. Exceedances of bacterial standards were observed in most of the systems. However, the areas of impact were generally spatially limited, and contaminant concentrations decreased below California Ocean Plan standards typically within 2-3 days. The largest bacterial concentrations occurred in the Tijuana River system where exceedances of fecal indicator bacteria were noted well away from the river mouth. Maximum nitrate concentrations (~40 μM) occurred in the San Pedro Shelf region near the mouth of the Los Angeles River. Based on the results of general linear models, individual sources of stormwater differ in both nutrient concentrations and the concentration and composition of fecal indicator bacteria. While nutrients appeared to decrease in plume waters due to simple mixing and dilution, the concentration of fecal indicator bacteria in plumes depends on more than loading and dilution rates. The relationships between contaminants (nutrients and fecal indicator bacteria) and plume indicators (salinity and total suspended solids) were not strong indicating the presence of other potentially important sources and/or sinks of both nutrients and fecal indicator bacteria. California Ocean Plan standards were often exceeded in waters containing greater than 10% stormwater (<28-30 salinity range). The median concentration dropped below the standard in the 32-33 salinity range (1-4% stormwater) for total coliforms and Enterococcus spp. and in the 28-30 salinity range (10-16% stormwater) for fecal coliforms. Nutrients showed a similar pattern with the highest median concentrations in water with greater than 10% stormwater. Relationships between colored dissolved organic matter (CDOM) and salinity and between total suspended solids and beam attenuation indicate that readily measurable, optically active variables can be used as proxies to provide at least a qualitative, if not quantitative, evaluation of the distribution of the dissolved, as well as the particulate, components of stormwater plumes. In this context, both CDOM absorption and the beam attenuation coefficient can be derived from satellite ocean color measurements of inherent optical properties suggesting that remote sensing of ocean color should be useful in mapping the spatial areas and durations of impacts from these contaminants.

Fog chemistry in the Texas-Louisiana Gulf Coast corridor

NASA Astrophysics Data System (ADS)

Raja, Suresh; Raghunathan, Ravikrishna; Yu, Xiao-Ying; Lee, Taehyoung; Chen, Jing; Kommalapati, Raghava R.; Murugesan, Karthik; Shen, Xinhua; Qingzhong, Yuan; Valsaraj, Kalliat T.; Collett, Jeffrey L.

Fog samples were collected in two population centers of the US Gulf Coast (Houston, Texas and Baton Rouge, Louisiana) using Caltech active strand cloud collectors. A total of 32 fogwater samples were collected in Baton Rouge (November 2004-February 2005) and Houston (February 2006). These samples were analyzed for pH, total and dissolved organic carbon, major inorganic ions, and a variety of organic compounds including organic acids, aromatics, carbonyls, and linear alkanes. Fogs in both environments were of moderate density, with typical fog liquid water contents <100 mg m -3. Fog samples collected in Houston reflect a clear influence of marine and anthropogenic inputs, while Baton Rouge samples also reflect agricultural inputs. The volume-weighted mean fog pH was somewhat more acidic (˜4.3) in Houston than in Baton Rouge (˜5.0). A wide pH range was observed in fog at both locations. Houston fog had higher concentrations of Cl -, NO 3-, Na +, Mg 2+, and Ca 2+. Sulfate to nitrate ratios were high in fogs at both locations, typical of many clouds in the eastern US. Total organic carbon concentrations were much higher in Houston fogs than in Baton Rouge fogs. Efforts to speciate dissolved organic carbon (DOC) reveal large contributions from organic acids and carbonyls, with smaller contributions from other organic compound families including aromatics, alkanes, amides, and alcohols. Approximately 40% of the fog DOC was unspeciated in samples from both study locations.

Occupational exposure to airborne asbestos from phenolic molding material (Bakelite) during sanding, drilling, and related activities.

PubMed

Mowat, Fionna; Bono, Michael; Lee, R J; Tamburello, Susan; Paustenbach, Dennis

2005-10-01

In this study, a historical phenolic (Bakelite) molding material, BMMA-5353, was tested to determine the airborne concentrations of asbestos fibers released during four different activities (sawing, sanding, drilling, and cleanup of dust generated from these activities). Each activity was performed for 30 min, often in triplicate. The primary objective for testing BMMA-5353 was to quantitatively determine the airborne concentration of asbestos fibers, if any, in the breathing zone of workers. Uses of this product typically did not include sawing or sanding, but it may have been drilled occasionally. For this reason, only small quantities were sawed, sanded, and drilled in this simulation study. Personal (n = 40), area (n = 80), and background/clearance (n = 88) air samples were collected during each activity and analyzed for total fiber concentrations using phase contrast microscopy (PCM) and, for asbestos fiber counts, transmission electron microscopy (TEM). The raw PCM-total fiber concentrations were adjusted based on TEM analyses that reported the fraction of asbestos fibers, to derive a PCM-asbestos concentration that would enable calculation of an 8-hour time-weighted average (TWA). The estimated 8-hour TWAs ranged from 0.006 to 0.08 fibers per cubic centimeter using a variety of worker exposure scenarios. Therefore, assuming an exposure scenario in which a worker uses power tools to cut and sand products molded from BMMA-5353 and similar products in the manner evaluated in this study, airborne asbestos concentrations should not exceed current or historical occupational exposure limits.

Study on emission characteristics of hybrid bus under driving cycles in typical Chinese city

NASA Astrophysics Data System (ADS)

Xie, Yongdong; Xu, Guangju

2017-09-01

In this study, hybrid city bus was taken as the research object, through the vehicle drum test, the vehicle emissions of hybrid bus, the transient emissions of gas pollutants, as well as the particle size and number distribution were surveyed. The results of the studies are listed as follows: First, compared to traditional fuel bus, hybrid bus could reduce about 44% of the NOx emissions, 33% of the total hydrocarbon emissions, and 51% of the particles emissions. Furthermore, the distribution of particles number concentration of test vehicle became high in middle and low in both sides. More specifically, the particle number concentration was mainly concentrated in the range from 0.021 to 0.755μm, the maximum was 0.2μm, and particle size of particulate matter (PM) less than 1.2μm accounted for 95% of the total number concentration. Particulate mass concentration was increased with increment of particle size, and the maximum of particulate mass (PM) concentration was 6.2μm. On average, whether traditional fuel bus or hybrid bus, the particle size of particulate matter(PM) less than 2.5μm accounted for more than 98% in the particles emission. It is found that the particles are more likely to deposit to the lung, respiratory bronchioles and alveoli, causing respiratory and lung diseases. Therefore, how to control the PM emissions of hybrid bus is the key factor of the study.

Odor Detection by Humans of Lineal Aliphatic Aldehydes and Helional as Gauged by Dose–Response Functions

PubMed Central

Abraham, Michael H.

2010-01-01

We have measured concentration detection (i.e., psychometric) functions to determine the odor detectability of homologous aliphatic aldehydes (propanal, butanal, hexanal, octanal, and nonanal) and helional. Subjects (16 ≤ n ≤ 18) used a 3-alternative forced-choice procedure against carbon-filtered air (blanks), under an ascending concentration approach. Generation, delivery, and control of each vapor were achieved via an 8-station vapor delivery device. Gas chromatography served to quantify the concentrations presented. Group and individual functions were modeled by a sigmoid (logistic) equation. Odor detection thresholds (ODTs) were defined as the concentration producing a detectability (P) halfway (P = 0.5) between chance (P = 0.0) and perfect detection (P = 1.0). ODTs decreased with carbon chain length: 2.0, 0.46, 0.33, and 0.17 ppb, respectively, from propanal to octanal, but the threshold increased for nonanal (0.53 ppb), revealing maximum sensitivity for the 8-carbon member. The strong olfactory receptor (OR) ligands octanal and helional (0.14 ppb) showed the lowest thresholds. ODTs fell at the lower end of previously reported values. Interindividual variability (ODT ratios) amounted to a factor ranging from 10 to 50, lower than typically reported, and was highest for octanal and hexanal. The behavioral dose–response functions emerge at concentrations 2–5 orders of magnitude lower than those required for functions tracing the activation of specific human ORs by the same aldehydes in cell/molecular studies, after all functions were expressed as vapor concentrations. PMID:20190010

Cosmogenic nuclide budgeting of floodplain sediment transfer

NASA Astrophysics Data System (ADS)

Wittmann, H.; von Blanckenburg, F.

2009-08-01

Cosmogenic nuclides produced in quartz may either decay or accumulate while sediment is moved through a river basin. A change in nuclide concentration resulting from storage in a floodplain is potentially important in large drainage basins in which sediment is prone to repeated burial and remobilization as a river migrates through its floodplain. We have modeled depth- and time-dependent cosmogenic nuclide concentration changes for 10Be, 26Al, and 14C during sediment storage and mixing in various active floodplain settings ranging from confined, shallow rivers with small floodplains to foreland-basin scale floodplains traversed by deep rivers. Floodplain storage time, estimated from channel migration rates, ranges from 0.4 kyr for the Beni River basin (Bolivia) to 7 kyr for the Amazon River basin, while floodplain storage depth, estimated from channel depth, ranges from 1 to 25 m. For all modeled active floodplain settings, the long-lived nuclides 10Be and 26Al show neither significant increase in nuclide concentration from irradiation nor decrease from decay. We predict a hypothetical response time after which changes in 10Be or 26Al concentrations become analytically resolvable. This interval ranges from 0.07 to 2 Myr and exceeds in all cases the typical residence time of sediment in a floodplain. Due to the much shorter half life of 14C, nuclide concentrations modeled for the in situ-produced variety of this nuclide are, however, sensitive to floodplain storage on residence times of < 20 kyr. The cosmogenic nuclide composition of old deposits in currently inactive floodplains that have been isolated for periods of millions of years from the river that once deposited them is predicted to either increase or decrease in 10Be and 26Al concentration, depending on the depositional depth. These conditions can be evaluated using the 26Al/ 10Be ratio that readily discloses the depth and duration of storage. We illustrate these models with examples from the Amazon basin. As predicted, modern bedload collected from an Amazon tributary, the Bolivian Beni River, shows no systematic change in nuclide concentration as sediment is moved through 500 km of floodplain by river meandering. In contrast, in the central Amazon floodplain currently untouched by the modern river system, low 26Al/ 10Be ratios account for minimum burial depths of 5 to 10 m for a duration of > 5 Myr. The important result of this analysis is that in all likely cases of active floodplains, cosmogenic 10Be and 26Al concentrations remain virtually unchanged over the interval sediment usually spends in the basin. Thus, spatially-averaged denudation rates of the sediment-producing area can be inferred throughout the entire basin, provided that nuclide production rates are scaled for the altitudes of the sediment-producing area only, because floodplain storage does not modify nuclide concentrations introduced from the sediment source area.

Kinetics of mercuric chloride retention by soils

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

Amacher, M.C.; Selim, H.M.; Iskandar, I.K.

A nonlinear multireaction model was used to describe kinetic data for HgCl{sub 2} retention by five soils. A three-parameter version of the model consisting of a reversible nonlinear (nth order, n < 1) reaction and an irreversible first-order reaction was capable of describing HgCl{sub 2} retention data for Cecil (clayey, kaolinitic, thermic Typic Kanhapludult) and Windsor (mixed, mesic Typic Udipsamment) soils at all initial solution Hg concentrations, and data for Norwood, (fine-silty, mixed (calcareous), thermic, Typic Udifluvent), Olivier (fine-silty, mixed, thermic Aquic Fragiudalt), and Sharkey (very-fine, montmorillonitic, nonacid, thermic Vertic Haplaquept) soils at initial solution Hg concentrations below 5 mg/L.more » A five-parameter version of the model, with an added reversible nonlinear reaction, provided a more accurate description of the retention data for the Norwood, Olivier, and Sharkey soils at initial solution Hg concentrations above 5 mg/L. The second reaction needed to describe the data at higher Hg concentrations suggests the presence of a second type of sorption sites, or a precipitation or coprecipitation reaction not encountered at lower Hg concentrations. Release of Hg from the soils was induced by serial dilution of the soil solution, but not all the soil Hg was reversibly retained. This was also indicated by the model. Release of soil Hg depended on the concentration of retained Hg with significant Hg release occurring only at high concentrations of retained Hg. A multireaction model is needed to describe Hg retention in soils because of the many solid phases that can remove Hg from solution.« less

Total Mercury and Methylmercury in the Great Egg Harbor River Watershed, New Jersey, USA

NASA Astrophysics Data System (ADS)

Barringer, J. L.; Riskin, M. L.; Szabo, Z.; Fischer, J. M.; Reilly, P. A.; Rosman, R.; Bonin, J. L.; Heckathorn, H. A.

2007-12-01

Hydrologic and biogeochemical conditions are important factors in the transport and distribution of mercury (Hg) in New Jersey Coastal Plain watersheds that contain extensive freshwater wetlands and where Hg bioaccumulation is of concern. U.S. Geological Survey studies found Hg concentrations in top predator fish from the Great Egg Harbor River mainstem that ranged from 2.9 to 4.5 mg/kg (dry wt.) and exceeded 10 ng/L in the watershed's acidic streams. An ongoing study with the N.J. Department of Environmental Protection indicates that atmospheric deposition of Hg to the wetlands and streams may be augmented by substantial contributions of Hg from ground water. Although background levels of Hg in water from the underlying aquifer typically are less than 10 ng/L, concentrations in water from more than 600 domestic wells in southern New Jersey have been shown to exceed the drinking-water maximum contaminant level of 2,000 ng/L. Therefore, to determine ground-water inputs to the streams, samples of ground water discharging to the tributaries and mainstem as well as streamwater samples collected during various flow conditions were analyzed for total Hg and methylmercury (MeHg). Total Hg concentrations in ground water discharging to the tributaries and mainstem were low to moderate (0.29-22 ng/L) in relatively undeveloped areas (including wetlands), but higher (36 and 177 ng/L) in two urban/suburban areas where much of the Hg was in particulate form. In recent and ongoing studies, total Hg concentrations in unfiltered samples of surface water, except those for one suburban tributary, have ranged from 2.13 to 37.7 ng/L. Concentrations in the suburban tributary have ranged from 50 ng/L during a dry period to 250 ng/L during a wet period. Hg concentrations in samples from a wetlands-embedded reach of the mainstem varied markedly with flow. In addition to increases in concentrations of total Hg, UV absorbance and concentrations of dissolved organic carbon also increased with flow after rain events, whereas pH and concentrations of dissolved oxygen and nitrate decreased. These flow-related changes apparently result from inputs of water that has percolated through acidic, reducing wetlands soils. The biogeochemical environment of these soils, on the basis of hydrogen sulfide odors detected during piezometer placement, supports sulfate reduction and likely promotes methylation of Hg. MeHg concentrations were 0.48 ng/L after a rainfall in discharge from 0.8 m below the streambed at a mainstem wetlands site. Downstream, where the channel briefly emerges from wetlands, MeHg was detectable during a dry period only in the hyporheic-zone water from 0.15 m below the streambed and in ground water from a depth of 0.3 m (0.15 ng/L and 0.05 ng/L, respectively). MeHg was not detected in the ground-water samples from deeper points below the streambeds, but concentrations in surface water ranged from 0.17 to 2.88 ng/L. The concentration from a tributary surrounded by urban/suburban development was highest. MeHg concentrations in mainstem water did not always increase with streamflow; variations in antecedent hydrologic conditions in the wetlands may explain the unpredictable relation of concentration to flow. Overall, total Hg appears to be contributed to the streams by both ground water and atmospheric deposition, with methylation taking place at shallow levels in wetlands soils and stream sediments.

Implications of Decreased Nitrite Concentrations on Clostridium perfringens Outgrowth during Cooling of Ready-to-Eat Meats.

PubMed

Myers, Megan I; Sebranek, Joseph G; Dickson, James S; Shaw, Angela M; Tarté, Rodrigo; Adams, Kristin R; Neibuhr, Steve

2016-01-01

Increased popularity of natural and organic processed meats can be attributed to the growing consumer demand for preservative-free foods, including processed meats. To meet this consumer demand, meat processors have begun using celery juice concentrate in place of sodium nitrite to create products labeled as no-nitrate or no-nitrite-added meat products while maintaining the characteristics unique to conventionally cured processed meats. Because of flavor limitations, natural cures with celery concentrate typically provide lower ingoing nitrite concentrations for ready-to-eat processed meats than do conventional cures, which could allow for increased growth of pathogens, such as Clostridium perfringens, during cooked product cooling such as that required by the U.S. Department of Agriculture. The objective of this study was to investigate the implications associated with reduced nitrite concentrations for preventing C. perfringens outgrowth during a typical cooling cycle used for cooked products. Nitrite treatments of 0, 50, and 100 ppm were tested in a broth system inoculated with a three-strain C. perfringens cocktail and heated with a simulated product thermal process followed by a typical cooling-stabilization process. The nitrite concentration of 50 ppm was more effective for preventing C. perfringens outgrowth than was 0 ppm but was not as effective as 100 ppm. The interaction between nitrite and temperature significantly affected (P < 0.05) C. perfringens outgrowth in both total population and number of vegetative cells. Both temperature and nitrite concentration significantly affected (P < 0.05) C. perfringens spore survival, but the interaction between nitrite and temperature did not have a significant effect (P > 0.05) on spore outgrowth. Results indicate that decreased nitrite concentrations (50 ppm) have increased potential for total C. perfringens population outgrowth during cooling and may require additional protective measures, such as faster chilling rates.

Water-quality characteristics of stormwater runoff in Rapid City, South Dakota, 2008-14

USGS Publications Warehouse

Hoogestraat, Galen K.

2015-01-01

For the Arrowhead and Meade-Hawthorne sites, event-mean concentrations typically exceeded the TSS and bacteria beneficial-use criteria for Rapid Creek by 1–2 orders of magnitude. Comparing the two drainage basins, median TSS event-mean concentrations were more than two times greater at the Meade-Hawthorne outlet (520 milligrams per liter) than the Arrowhead outlet (200 milligrams per liter). Median fecal coliform bacteria event-mean concentrations also were greater at the Meade-Hawthorne outlet site (30,000 colony forming units per 100 milliliters) than the Arrowhead outlet site (17,000 colony forming units per 100 milliliters). A comparison to relevant standards indicates that stormwater runoff from the Downtown drainage basin exceeded criteria for bacteria and TSS, but concentrations generally were below standards for nutrients and metals. Stormwater-quality conditions from the Downtown drainage basin outfalls were similar to or better than stormwater-quality conditions observed in the Arrowhead and Meade-Hawthorne drainage basins. Three wetland channels located at the outlet of the Downtown drainage basin were evaluated for their pollutant reduction capability. Mean reductions in TSS and lead concentrations were greater than 40 percent for all three wetland channels. Total nitrogen, phosphorus, copper, and zinc concentrations also were reduced by at least 20 percent at all three wetlands. Fecal coliform bacteria concentrations typically were reduced by about 21 and 36 percent at the 1st and 2nd Street wetlands, respectively, but the reduction at the 3rd Street wetland channel was nearly zero percent. Total wetland storage volume affected pollutant reductions because TSS, phosphorus, and ammonia reductions were greatest in the wetland with the greatest volume. Chloride concentrations typically increased from inflow to outflow at the 2nd and 3rd Street wetland channels.

Analysis of selected water-quality data for surface water in St. Tammany Parish, Louisiana, April-August 1995

USGS Publications Warehouse

Demcheck, Dennis K.

1996-01-01

Physical and chemical-related properties, concentrations of chemical constituents, which included major ions and nutrients, and concentrations of fecal-coliform bacteria were determined for 17 sites on 11 streams in St. Tammany Parish, Louisiana, during the period April-August 1995. The streams were sampled to assess the effects of different streamflow conditions on the concentrations of water-quality constituents. The streams included in the study were Tchefuncte River, Bogue Falaya, Abita River, Bayou Chinchouba, Bayou Castine, Cane Bayou, Bayou Lacombe, Bayou Liberty, Bayou Bonfouca, Bogue Chitto, and West Pearl River. Water-quality samples were collected under several hydrologic conditions. These conditions included a period of wet weather and sustained high river stages; a period of local storms several days apart and river stages typical of that situation; and a period of dry weather and low river stages. The concentrations of inorganic chemical constituents in water from the upstream sites generally were low. Concentrations from the downstream sites varied and were higher. Nutrient and fecal-coliform bacteria concentrations varied and indicated that degraded water-quality conditions that typically occur during storms persisted less than 1-3 days. In general, the larger the drainage basin, the longer it takes for the stream to recover. Fecal-coliform concen- trations reflected the effects of small, isolated storms in the area. Bayou Castine, sampled immediately after a storm, had a fecal-coliform concentration of 26,000 colonies per 100 milliliters. The stream was resampled 24 hours later, and the fecal-coliform concentration had decreased to 1,700 colonies per 100 milliliters. This is an indication of the rapid water-quality changes that typically occur in small streams.

Concentrations, fluxes, and yields of nitrogen, phosphorus, and suspended sediment in the Illinois River basin, 1996-2000

USGS Publications Warehouse

Terrio, Paul J.

2006-01-01

Concentrations, spatial and temporal variations, and fluxes of nitrogen, phosphorus, and suspended sediment were determined for 16 streams in the Illinois River Basin, Illinois from October 1996 through September 2000. Water samples were collected through the National Water-Quality Assessment's Lower Illinois River Basin (LIRB) and Upper Illinois River Basin (UIRB) Study Units on a monthly to weekly frequency from watersheds representing predominantly agricultural and urban land, as well as areas of mixed land-use. Streams in agricultural watersheds had high concentrations and fluxes of nitrate nitrogen, whereas streams in predominantly urban watersheds had high concentrations (above background levels) of ammonia nitrogen, organic nitrogen, and phosphorus. Median concentrations of nitrate nitrogen and total phosphorus were similar at the two Illinois River sampling stations (Illinois River at Ottawa, Ill. and Illinois River at Valley City, Ill.) that represented the downstream points of the UIRB and LIRB Study Units, respectively, and integrated multiple land-use areas. Concentrations of nitrogen were typically highest in the spring and lowest in the fall in agricultural watersheds, but highest in the winter in urban watersheds. Phosphorus concentrations in urban watersheds were highest in the fall and winter, but there was minimal seasonal variation in phosphorus concentrations in agricultural watersheds. Concentrations of nitrate and total nitrogen were affected primarily by non-point sources and hydrologic factors such as streamflow, storm intensity, watershed configuration, and soil permeability, whereas concentrations of phosphorus were affected largely by point-source contributions that typically have little seasonal variation. Seasonal variation in hydrologic conditions was an important factor for seasonal variation in nutrient concentration. Fluxes and yields of nitrogen and phosphorus forms varied substantially throughout the Illinois River Basin, and yields of specific nutrient forms were determined primarily by upstream land uses. Yields of nitrate nitrogen were highest in predominantly agricultural watersheds, whereas yields of phosphorus and ammonia nitrogen were highest in urban watersheds with wastewater effluent contributions. Yields of both total nitrogen and total phosphorus were similar at the two Illinois River stations representing the integrated UIRB and LIRB Study Units. Concentrations of suspended sediment ranged from 1 to 3,110 milligrams per liter (mg/L), with median concentrations generally higher in the UIRB. Suspended-sediment concentrations were highest and most variable in the LaMoine River Basin. The median concentration of suspended sediment in the Illinois River at Valley City, Ill. (155 mg/L) was twice as high as that at Ottawa, Ill. (80 mg/L). Fluxes of suspended sediment generally corresponded to watershed size and yields from agricultural watersheds were larger than yields from urban watersheds. The flux in the Illinois River at Valley City, Ill. (4,880,000 tons per year) was approximately four times the flux in the Illinois River at Ottawa, Ill. (1,060,000 tons per year).