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Sample records for radon-222 concentration trend

  1. Predicting indoor radon-222 concentration

    SciTech Connect

    Stowe, M.H.

    1994-12-31

    Radon, a cause of lung cancer among miners, is being investigated as a source of lung cancer in the general population due to long-term low-level exposures in residences. Assessment of cumulative residential radon exposure entails measurements in past residences, some of which no longer exist or are not accessible. Estimates of radon concentrations in these missing homes are necessary for analysis of the radon-lung cancer association. Various approaches have been used by researchers attempting to predict the distribution of radon measurements in homes from specified geological and building characteristics. This study has modelled the set of basement radon measurements of 3788 Connecticut homes with several of these approaches, in addition to a descriptive tree method not previously utilized, and compared their validity on a random subset of homes not used in model construction. Each geographical and geological variable was more predictive of radon concentration than any of the housing characteristics. The single variable which explained the largest fraction of the variability in radon readings was the mean radon concentration for the zipcode area in which the house was located (R{sup 2} = .157). Soil characteristics at individual housing sites were not available for these analyses. They would be expected to increase the predictive power of the models. Multiple regression models, both additive and multiplicative, were not able to explain more than 22% of the variation in radon readings. Variables found to be significant in these models were zipcode mean, residential radon mean of bedrock unit, building age, type of foundation walls, type of water supply, aeroradioactivity reading, and lithology of the bedrock. A site potential index, based upon a classification of the bedrock underlying the house, was a better predictor of indoor radon level than other single geological variables, yet only explained 8% of the radon variability.

  2. Radon-222 concentrations in ground water and soil gas on Indian reservations in Wisconsin

    USGS Publications Warehouse

    DeWild, John F.; Krohelski, James T.

    1995-01-01

    For sites with wells finished in the sand and gravel aquifer, the coefficient of determination (R2) of the regression of concentration of radon-222 in ground water as a function of well depth is 0.003 and the significance level is 0.32, which indicates that there is not a statistically significant relation between radon-222 concentrations in ground water and well depth. The coefficient of determination of the regression of radon-222 in ground water and soil gas is 0.19 and the root mean square error of the regression line is 271 picocuries per liter. Even though the significance level (0.036) indicates a statistical relation, the root mean square error of the regression is so large that the regression equation would not give reliable predictions. Because of an inadequate number of samples, similar statistical analyses could not be performed for sites with wells finished in the crystalline and sedimentary bedrock aquifers.

  3. Radon 222

    Integrated Risk Information System (IRIS)

    Radon 222 ; CASRN 14859 - 67 - 7 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effec

  4. Distribution of Airborne Radon-222 Concentrations in U.S. Homes

    NASA Astrophysics Data System (ADS)

    Nero, A. V.; Schwehr, M. B.; Nazaroff, W. W.; Revzan, K. L.

    1986-11-01

    Apparently large exposures of the general public to the radioactive decay products of radon-222 present in indoor air have led to systematical appraisal of monitoring data from U.S. single-family homes; several ways of aggregating data were used that take into account differences in sample selection and season of measurements. The resulting distribution of annual-average radon-222 concentrations can be characterized by an arithmetic mean of 1.5 picocurie per liter (55 becquerels per cubic meter) and a long tail with 1 to 3% of homes exceeding 8 picocuries per liter, or by a geometric mean of 0.9 picocurie per liter and a geometric standard deviation of about 2.8. The standard deviation in the means is 15%, estimated from the number and variability of the available data sets, but the total uncertainty is larger because these data may not be representative. Available dose-response data suggest that an average of 1.5 picocuries per liter contributes about 0.3% lifetime risk of lung cancer and that, in the million homes with the highest concentrations, where annual exposures approximate or exceed those received by under-ground uranium miners, long-term occupants suffer an added lifetime risk of at least 2%, reaching extraordinary values at the highest concentrations observed.

  5. Optimized measurement of radium-226 concentration in liquid samples with radon-222 emanation.

    PubMed

    Perrier, Frédéric; Aupiais, Jean; Girault, Frédéric; Przylibski, Tadeusz A; Bouquerel, Hélène

    2016-06-01

    Measuring radium-226 concentration in liquid samples using radon-222 emanation remains competitive with techniques such as liquid scintillation, alpha or mass spectrometry. Indeed, we show that high-precision can be obtained without air circulation, using an optimal air to liquid volume ratio and moderate heating. Cost-effective and efficient measurement of radon concentration is achieved by scintillation flasks and sufficiently long counting times for signal and background. More than 400 such measurements were performed, including 39 dilution experiments, a successful blind measurement of six reference test solutions, and more than 110 repeated measurements. Under optimal conditions, uncertainties reach 5% for an activity concentration of 100 mBq L(-1) and 10% for 10 mBq L(-1). While the theoretical detection limit predicted by Monte Carlo simulation is around 3 mBq L(-1), a conservative experimental estimate is rather 5 mBq L(-1), corresponding to 0.14 fg g(-1). The method was applied to 47 natural waters, 51 commercial waters, and 17 wine samples, illustrating that it could be an option for liquids that cannot be easily measured by other methods. Counting of scintillation flasks can be done in remote locations in absence of electricity supply, using a solar panel. Thus, this portable method, which has demonstrated sufficient accuracy for numerous natural liquids, could be useful in geological and environmental problems, with the additional benefit that it can be applied in isolated locations and in circumstances when samples cannot be transported. PMID:26998570

  6. Optimized measurement of radium-226 concentration in liquid samples with radon-222 emanation.

    PubMed

    Perrier, Frédéric; Aupiais, Jean; Girault, Frédéric; Przylibski, Tadeusz A; Bouquerel, Hélène

    2016-06-01

    Measuring radium-226 concentration in liquid samples using radon-222 emanation remains competitive with techniques such as liquid scintillation, alpha or mass spectrometry. Indeed, we show that high-precision can be obtained without air circulation, using an optimal air to liquid volume ratio and moderate heating. Cost-effective and efficient measurement of radon concentration is achieved by scintillation flasks and sufficiently long counting times for signal and background. More than 400 such measurements were performed, including 39 dilution experiments, a successful blind measurement of six reference test solutions, and more than 110 repeated measurements. Under optimal conditions, uncertainties reach 5% for an activity concentration of 100 mBq L(-1) and 10% for 10 mBq L(-1). While the theoretical detection limit predicted by Monte Carlo simulation is around 3 mBq L(-1), a conservative experimental estimate is rather 5 mBq L(-1), corresponding to 0.14 fg g(-1). The method was applied to 47 natural waters, 51 commercial waters, and 17 wine samples, illustrating that it could be an option for liquids that cannot be easily measured by other methods. Counting of scintillation flasks can be done in remote locations in absence of electricity supply, using a solar panel. Thus, this portable method, which has demonstrated sufficient accuracy for numerous natural liquids, could be useful in geological and environmental problems, with the additional benefit that it can be applied in isolated locations and in circumstances when samples cannot be transported.

  7. Helium 4 and radon 222 concentrations in groundwater and soil as indicators of zones of fracture concentration in unexposed rock

    SciTech Connect

    Banwell, G.M.; Parizek, R.R.

    1988-01-10

    The presence of zones of fracture concentration in unexposed rock may be partially assessed by measuring the concentrations of /sup 4/He and /sup 222/Rn in groundwater and soil gas. Helium 4 in groundwater and soil gas and /sup 222/Rn in groundwater were measured in the vicinity of two intersecting linements in Lehigh County, Pennsylvania. The limeaments are thought to mark deep fracture systems which provide conduits for the migration of /sup 4/He and /sup 222/Rn. High groundwater /sup 4/He concentrations revealed the presence of the two lineaments. Low groundwater /sup 222/Rn activities are found near the lineaments and qualitatively support a numerical model which relates low /sup 222/Rn activity to high fracture transmissivity. Radon 222 activity correlates most strongly with the presence of H/sub 2/S in groundwater, implying that geochemical controls or groundwater circulation patterns strongly influence radon concentration. Soil gas concentrations of /sup 4/He barely exceeded background levels and did not reliably indicate the lineament zones. The data show that groundwater /sup 4/He concentrations may be used to identify fracture zones in unexposed bedrock. copyright American Geophysical Union 1988

  8. Measurement of Indoor Radon-222 and Radon-220 Concentrations in Central Japan

    SciTech Connect

    Oka, Mitsuaki; Shimo, Michikuni; Tokonami, Shinji; Sorimachi, Atsuyuki; Takahashi, Hiromichi; Ishikawa, Tetsuo

    2008-08-07

    A passive-type radon/thoron detector was used for measuring indoor radon and thoron concentrations at 90 dwellings in Aichi and Gifu prefectures in central Japan during 90 days from December, 2006 to March, 2007. The radon and thoron concentrations were 21.1 Bq/m3 and 25.1 Bq/m3, respectively. The dose due to radon and thoron in dwellings was roughly evaluated as 0.7 mSv/y and 2.4 mSv/y, respectively. The examination of the geological factor and house condition having an effect on indoor radon concentration was performed.

  9. Variation of radon-222 concentration in exposure systems air under different conditions of exposure

    NASA Astrophysics Data System (ADS)

    Mamoon, A.; Abdul-Fattah, A. A.; Qari, T. M.

    1994-07-01

    Simplified, laboratory scale systems, namely ordinary laboratory desiccators and cylindrical containers were tested with regard to their reliability as exposure systems for determining certain parameters of radon emanation from locally obtained crushed granite rock samples. The samples were placed inside the exposure systems. Activity concentration of emanated radon in the exposure systems air increased with increase of mass of granite sample in the desiccator and with length of the exposure period. Activity concentration of radon was high near the granitic source but decreased with vertical distance from it when the exposure system was semiclosed but activity was homogeneous when the system was completely closed. The cylindrical exposure system was used in assessing Ra-226 content in some crushed granitic samples identified as altered alkali granite and found to be: 0.024 Bq g-1 (0.65 pCig-1). Rn-222 emanation rate from the same samples was: 0.013 Bq m-2 s-1 (0.34 pCi m-2 s-1). Saturation density thickness for a mixed sample of pure and alkali granites was found to be 116 g cm-2. The results agree in general with reported observations and support the reliability of the exposure systems used.

  10. Use of radon-222 to evaluate the influence of groundwater discharge on fecal indicator bacteria concentrations in the near-shore ocean, Malibu, California

    NASA Astrophysics Data System (ADS)

    Izbicki, J. A.; Burton, C.; Swarzenski, P. W.

    2011-12-01

    To protect beach-goers from waterborne disease, California requires water-quality monitoring for fecal indicator bacteria (FIB) at beaches having more than 50,000 visits annually. The source(s) of FIB in ocean beaches in excess of marine recreational water standards is often not known, or may be incorrectly identified. Onsite wastewater treatment systems (OWTS) used to treat residential and commercial sewage have been implicated by regulatory agencies as a possible source of FIB to recreational ocean beaches, near Malibu, California. For this to occur, treated wastewater must first move through groundwater prior to discharge at the ocean. Groundwater discharge to the ocean near Malibu Lagoon (the estuary of Malibu Creek) is complicated by seasonally changing water levels in the lagoon. The lagoon is isolated from the ocean by a sand berm that develops across the mouth of the lagoon during the dry season. Higher water levels in the lagoon during the dry season, and lower water-levels during the wet season, cause seasonal changes in the direction of groundwater flow and the magnitude of discharge from the adjacent small (3,400 hectare), alluvial aquifer. Radon-222, an indicator of groundwater discharge, was measured in Malibu Lagoon, in the near-shore ocean adjacent to the lagoon, and in the near-shore ocean adjacent to unsewered residential development to determine the timing and magnitude of groundwater discharge. During the dry season, when the berm of the lagoon was closed and the lagoon was isolated from the ocean, radon-222 concentrations in the near-shore ocean during low tide increased as water discharged from the lagoon through the berm. Enterococcus concentrations in the near-shore ocean increased to almost 600 Most Probable Number (MPN) per 100 milliliter at this time. Radon-222 concentrations also increased at low tide as groundwater discharged to the ocean from the adjacent alluvial aquifer underlying the unsewered residential development, but there was

  11. Radon-222 in the ground water of Chester County, Pennsylvania

    USGS Publications Warehouse

    Senior, Lisa A.

    1998-01-01

    Radon-222 concentrations in ground water in 31 geologic units in Chester County, Pa., were measured in 665 samples collected from 534 wells from 1986 to 1997. Chester County is underlain by schists, gneisses, quartzites, carbonates, sandstones, shales, and other rocks of the Piedmont Physiographic Province. On average, radon concentration was measured in water from one well per 1.4 square miles, throughout the 759 square-mile county, although the distribution of wells was not even areally or among geologic units. The median concentration of radon-222 in ground water from the 534 wells was 1,400 pCi/L (picocuries per liter). About 89 percent of the wells sampled contained radon-222 at concentrations greater than 300 pCi/L, and about 11 percent of the wells sampled contained radon-222 at concentrations greater than 5,000 pCi/L. The highest concentration measured was 53,000 pCi/L. Of the geologic units sampled, the median radon-222 concentration in ground water was greatest (4,400 pCi/L) in the Peters Creek Schist, the second most areally extensive formation in the county. Signifi- cant differences in the radon-222 concentrations in ground water among geologic units were observed. Generally, concentrations in ground water in schists, quartzites, and gneisses were greater than in ground water in anorthosite, carbonates, and ultramafic rocks. The distribution of radon-222 in ground water is related to the distribution of uranium in aquifer materials of the various rock types. Temporal variability in radon-222 concentrations in ground water does not appear to be greater than about a factor of two for most (75 percent) of wells sampled more than once but was observed to range up to almost a factor of three in water from one well. In water samples from this well, seasonal variations were observed; the maximum concentrations were measured in the fall and the minimum in the spring.

  12. Acute Exposure from RADON-222 and Aerosols in Drinking Water

    NASA Astrophysics Data System (ADS)

    Bernhardt, George Paul, IV

    Radon-222 in water is released when the water is aerated, such as during showering. As a result, a temporary burst of radon-222 can appear as a short term, or acute, exposure. This study looked at homes with radon-222 concentrations in water from 800 picocuries per liter (pCi/l) to 53,000 pCi/l to determine the buildup of radon gas in a bathroom during showering. Samples from the tap and drain, compared to determine the percentage of radon-222 released, showed that between 58% and 88% of radon-222 in the water was released. The resultant radon-222 increase in air, measured with a flow-through detector, ranged from 2 pCi/l to 114 pCi/l in bathrooms due to a 10 to 15 minute shower with water flow rates ranging from 3 l/min to 6 l/min. Significantly, these rates did not fall rapidly but stayed approximately the same for up to 15 minutes after the water flow ceased. In examining exposures, the true danger is in the radon-222 progeny rather than the radon itself. The progeny can be inhaled and deposited in the tracheobronchial passages in the lung. Filter samples of bathroom air measured in a portable alpha spectrometer showed an increase in radon-222 progeny, notably polonium-218 and -214, in the air after showering. These increases were gradual and were on the order of 0.5 pCi/l at the highest level. Tap samples measured in a portable liquid scintillator showed that the progeny are present in the water but are not in true secular equilibrium with the radon-222 in the water. Therefore, the radon-222 does not have to decay to produce progeny since the progeny are already present in the water. A two stage sampler was used to examine the percentage of radiation available in aerosols smaller than 7 microns. Repeated trials showed that up to 85% of the radiation available in the aerosols is contained in the smaller, more respirable particles.

  13. Radon ((222)Rn) concentration in indoor air near the coal mining area of Nui Beo, North of Vietnam.

    PubMed

    Nhan, Dang Duc; Fernando, Carvalho P; Thu Ha, Nguyen Thi; Long, Nguyen Quang; Thuan, Dao Dinh; Fonseca, Heloisa

    2012-08-01

    Concentrations of radioactive radon gas ((222)Rn) were measured using passive monitors based on LR115 solid state track detectors during June-July 2010 in indoor air of dwellings in the Nui Beo coal mining area, mostly in Cam Pha and Ha Long coastal towns, Quang Ninh province, in the North of Vietnam. Global results of (222)Rn concentrations indoors varied from ≤6 to 145 Bq m(-3) averaging 46 ± 26 Bq m(-3) (n = 37), with a median value of 47 Bq m(-3). This was similar to outdoor (222)Rn concentrations in the region, averaging 43 ± 19 Bq m(-3) (n = 10), with a median value of 44 Bq m(-3). Indoor (222)Rn concentrations in the coastal town dwellings only were in average lower although not significantly different from indoor (222)Rn concentrations measured at the coal storage field near the harbor, 67 ± 4 Bq m(-3) (n = 3). Furthermore, there was no significant difference in the average (222)Rn concentration in indoor air measured in the coastal towns region and those at the touristic Tuan Chau Island located about 45 km south of the coal mine, in the Ha Long Bay. The indoor (222)Rn concentration in a floating house at the Bai Tu Long Bay, and assumed as the best estimate of the baseline (222)Rn in surface air, was 27 ± 3 Bq m(-3) (n = 3). Indoor average concentration of (222)Rn in dwellings at the Ha Noi city, inland and outside the coal mining area, was determined at 30 Bq m(-3). These results suggest that (222)Rn exhalation from the ground at the Nui Beo coal mining area may have contributed to generally increase (222)Rn concentration in the surface air of that region up to 1.7 times above the baseline value measured at the Bai Tu Long Bay and Ha Noi. The average indoor concentration of (222)Rn in Cam Pha-Ha Long area is about one-third of the value of the so-called Action Level set up by the US EPA of 148 Bq m(-3). Results suggest that there is no significant public health risk from (222)Rn exposure in the study region.

  14. Occurrences of Uranium and Radon-222 in Groundwaters from Various Geological Environments in the Hoengseong Area

    NASA Astrophysics Data System (ADS)

    Jeong, Chan Ho; Lee, Yu Jin; Lee, Young Cheon; Choi, Hyeon Young; Yang, Jae Ha

    2016-04-01

    Groundwaters in granite, gneiss, and two-mica granite formations, including faults, in the Hoengseong area are examined to determine the relationship between their uranium and radon-222 contents and rock types. The chemical compositions of 38 groundwater samples and four surface water samples collected in the study area were analyzed. Sixteen of the samples showing high uranium and radon-222 contents were repeatedly analyzed. Surface radioactivities were measured at 30 points. The uranium and radon-222 concentrations in the groundwater samples were in the ranges of 0.02-49.3 μg/L and 20-906 Bq/L, respectively. Four samples for uranium and 35 samples for radon had concentrations exceeding the alternative maximum contaminant level of the US EPA. The chemical compositions of groundwaters indicated Ca(Na)-HCO3 and Ca(Na)-NO3(HCO3+Cl) types. The pH values ranged from 5.71 to 8.66. High uranium and radon-222 contents in the groundwaters occurred mainly at the boundary between granite and gneiss, and in the granite area. The occurrence of uranium did not show any distinct relationship to that of radon-222. The radon-222, an inert gas, appeared to be dissolved in the groundwater of the aquifer after wide diffusion along rock fractures, having been derived from the decay of uranium in underground rocks. The results in this study indicate that groundwater of neutral or weakly alkaline pH, under oxidizing conditions and with a high bicarbonate content is favorable for the dissolution of uranium and uranium complexes such as uranyl or uranyl-carbonate. Key word: uranium, radon-222, geological boundary, groundwater, chemical characteristics, surface radioactivity

  15. Measurement of the emanation of radon-222 from Danish soils.

    PubMed

    Damkjaer, A; Korsbech, U

    1985-10-01

    The radon-222 emanation from 70 samples of Danish soils, subsoils, and sedimentary rocks has been measured. Two methods have been employed. The first one is to follow the growth of the radon concentration in a radon-tight sample container by transferring small air samples to a scintillation flask detection system. The second one is to measure the equilibrium gamma-activities of lead-214 and bismuth-214 in the sample when the sample container is open and, subsequently, when it is closed. Based on the measured emanation rates the samples are grouped in three classes: 1) less than 5 atoms . sec-1 . kg-1, 2) from 5 to 10 atoms . sec-1 . kg-1, and 3) more than 10 atoms . sec-1 . kg-1. In class 3) some diatomitic clays have shown emanation rates as large as 100 atoms . sec-1 . kg-1.

  16. Evaluation of repeated measurements of radon-222 concentrations in well water sampled from bedrock aquifers of the Piedmont near Richmond, Virginia, USA: Effects of lithology and well characteristics

    SciTech Connect

    Harris, Shelley A. . E-mail: saharris@vcu.edu; Billmeyer, Ernest R.; Robinson, Michael A.

    2006-07-15

    Radon ({sup 222}Rn) concentrations in 26 ground water wells of two distinct lithologies in the Piedmont of Virginia were measured to assess variation in ground water radon concentrations (GWRC), to evaluate differences in concentrations related to well characteristics, lithology, and spatial distributions, and to assess the feasibility of predicting GWRC. Wells were sampled in accordance with American Public Health Association Method 7500 Rn-B, with modifications to include a well shaft profile analysis that determined the minimum purge time sufficient to remove the equivalent of one column of water from each well. Statistically significant differences in GWRC were found in the Trssu (1482{+-}1711 pCi/L) and Mpg (7750{+-}5188 pCi/L) lithologies, however, no significant differences were found among GWRC at each well over time. Using multiple regression, 86% of the variability (R {sup 2}) in the GWRC was explained by the lithology, latitudinal class, and water table elevation of the wells. The GWRC in a majority of the wells studied exceed US Environmental Protection Agency designated maximum contaminant level and AMCL. Results support modifications to sampling procedures and indicate that, in previous studies, variations in GWRC concentrations over time may have been due in part to differences in sampling procedures and not in source water.

  17. The Study of Equilibrium factor between Radon-222 and its Daughters in Bangkok Atmosphere by Gamma-ray Spectrometry

    NASA Astrophysics Data System (ADS)

    Rujiwarodom, Rachanee

    2010-05-01

    To study the Equilibrium between radon-222 and its daughters in Bangkok atmosphere by Gamma-ray spectrometry, air sample were collected on 48 activated charcoal canister and 360 glass fiber filters by using a high volume jet-air sampler during December 2007 to November 2008.The Spectra of gamma-ray were measured by using a HPGe (Hyper Pure Germanium Detector). In the condition of secular equilibrium obtaining between Radon-222 and its decay products, radon-222 on activated charcoal canister and its daughters on glass fiber filters collected in the same time interval were calculated. The equilibrium factor (F) in the open air had a value of 0.38 at the minimum ,and 0.75 at the maximum. The average value of equilibrium factor (F) was 0.56±0.12. Based on the results, F had variations with a maximum value in the night to the early morning and decreased in the afternoon. In addition, F was higher in the winter than in the summer. This finding corresponds with the properties of the Earth atmosphere. The equilibrium factor (F) also depended on the concentration of dust in the atmosphere. People living in Bangkok were exposed to average value of 30 Bq/m3 of Radon-222 in the atmosphere. The equilibrium factor (0.56±0.12) and the average value of Radon-222 showed that people were exposed to alpha energy from radon-222 and its daughters decay at 0.005 WL(Working Level) which is lower than the safety standard at 0.02 WL. Keywords: Radon, Radon daughters , equilibrium factor, Gamma -ray spectrum analysis ,Bangkok ,Thailand

  18. Radon-222 signatures of natural ventilation regimes in an underground quarry.

    PubMed

    Perrier, Frédéric; Richon, Patrick; Crouzeix, Catherine; Morat, Pierre; Le Mouël, Jean Louis

    2004-01-01

    Radon-222 activity concentration has been monitored since 1999 in an underground limestone quarry located in Vincennes, near Paris, France. It is homogeneous in summer, with an average value of 1700 Bq m(-3), and varies from 730 to 1450 Bq m(-3) in winter, indicating natural ventilation with a rate ranging from 0.5 to 2.4 x 10(-6) s(-1) (0.04-0.22 day(-1)). This hypothesis is supported by measurements in the vertical access pit where, in winter, a turbulent air current produces a stable radon profile, smoothly decreasing from 700 Bq m(-3) at 20 m depth to 300 Bq m(-3) at surface. In summer, a thermal stratification is maintained in the pit, but the radon-222 concentration jumps repeatedly between 100 and 2000 Bq m(-3). These jumps are due to atmospheric pressure pumping, which induces ventilation in the quarry at a rate of about 0.1 x 10(-6) s(-1) (0.009 day(-1)). Radon-222 monitoring thus provides a dynamical characterisation of ventilation regimes, which is important for the assessment of the long-term evolution of underground systems.

  19. Sampling and analysis for radon-222 dissolved in ground water and surface water

    USGS Publications Warehouse

    DeWayne, Cecil L.; Gesell, T.F.

    1992-01-01

    Radon-222 is a naturally occurring radioactive gas in the uranium-238 decay series that has traditionally been called, simply, radon. The lung cancer risks associated with the inhalation of radon decay products have been well documented by epidemiological studies on populations of uranium miners. The realization that radon is a public health hazard has raised the need for sampling and analytical guidelines for field personnel. Several sampling and analytical methods are being used to document radon concentrations in ground water and surface water worldwide but no convenient, single set of guidelines is available. Three different sampling and analytical methods - bubbler, liquid scintillation, and field screening - are discussed in this paper. The bubbler and liquid scintillation methods have high accuracy and precision, and small analytical method detection limits of 0.2 and 10 pCi/l (picocuries per liter), respectively. The field screening method generally is used as a qualitative reconnaissance tool.

  20. Ambient Radon-222 Monitoring in Amargosa Valley, Nevada

    SciTech Connect

    L.H. Karr; J.J. Tappen; D. Shafer; K.J. Gray

    2008-06-05

    As part of a program to characterize and baseline selected environmental parameters in the region around the proposed repository at Yucca Mountain, Nevada, ambient radon-222 monitoring was conducted in the rural community of Amargosa Valley, the community closest to the proposed repository site. Passive integrating radon monitors and a continuous radon monitoring instrument were deployed adjacent to the Community Environmental Monitoring Program (CEMP) (http://www.cemp.dri.edu/index.html) station located in the Amargosa Valley Community Center near the library. The CEMP station provided real-time ambient gamma exposure and meteorological data used to correct the integrated radon measurements as well as verify meteorological data collected by the continuous radon monitoring instrument. Additionally, different types of environmental enclosures that housed the monitors and instrument were used to determine if particular designs influenced the ambient radon measurements.

  1. Surface-water radon-222 distribution along the west-central Florida shelf

    USGS Publications Warehouse

    Smith, C.G.; Robbins, L.L.

    2012-01-01

    In February 2009 and August 2009, the spatial distribution of radon-222 in surface water was mapped along the west-central Florida shelf as collaboration between the Response of Florida Shelf Ecosystems to Climate Change project and a U.S. Geological Survey Mendenhall Research Fellowship project. This report summarizes the surface distribution of radon-222 from two cruises and evaluates potential physical controls on radon-222 fluxes. Radon-222 is an inert gas produced overwhelmingly in sediment and has a short half-life of 3.8 days; activities in surface water ranged between 30 and 170 becquerels per cubic meter. Overall, radon-222 activities were enriched in nearshore surface waters relative to offshore waters. Dilution in offshore waters is expected to be the cause of the low offshore activities. While thermal stratification of the water column during the August survey may explain higher radon-222 activities relative to the February survey, radon-222 activity and integrated surface-water inventories decreased exponentially from the shoreline during both cruises. By estimating radon-222 evasion by wind from nearby buoy data and accounting for internal production from dissolved radium-226, its radiogenic long-lived parent, a simple one-dimensional model was implemented to determine the role that offshore mixing, benthic influx, and decay have on the distribution of excess radon-222 inventories along the west Florida shelf. For multiple statistically based boundary condition scenarios (first quartile, median, third quartile, and maximum radon-222 inshore of 5 kilometers), the cross-shelf mixing rates and average nearshore submarine groundwater discharge (SGD) rates varied from 100.38 to 10-3.4 square kilometers per day and 0.00 to 1.70 centimeters per day, respectively. This dataset and modeling provide the first attempt to assess cross-shelf mixing and SGD on such a large spatial scale. Such estimates help scale up SGD rates that are often made at 1- to 10-meter

  2. Radon-222 from the island of hawaii: deep soils are more important than lava fields or volcanoes.

    PubMed

    Wilkening, M H

    1974-02-01

    The mean flux of radon-222 atoms from the island of Hawaii is 0.45 atom per square centimeter per second. Lava fields occupy 50 percent of the land area, but their radon flux is only 1 percent of that from deep volcanic soils. The island yields approximately 10 curies of radon-222 per hour to the air surrounding it. The radon-222 contribuition of volcanoes is negligible.

  3. Radiation Protection. Measurement of radioactivity in the environment - Air- radon 222. A proposed ISO standard.

    NASA Astrophysics Data System (ADS)

    Gillmore, G.; Woods, M.

    2009-04-01

    Radon isotopes (222, 220, 219) are radioactive gases produced by the disintegration of radium isotopes 226, 224 and 223, which are decay products of uranium238, thorium232 and uranium235 respectively. All are found in the earth's crust. Solid elements, also radioactive, are produced by radon disintegration. Radon is classed as a rare gas in the periodic table of elements, along with helium, argon, neon, krypton and xenon. When disintegrating, radon emits alpha particles and generates solid decay products, which are also radioactive (polonium, bismuth, lead etc.). The potential danger of radon lies in its solid decay products rather than the gas itself. Whether or not they are attached aerosols, radon decay products can be inhaled and deposited in the bronchopulmonary tree to varying depths according to their size. Radon today is considered to be the main source of human exposure to natural radiation. At the international level, radon accounts for 52% of global average exposure to natural radiation. Isotope 222 (48%) is far more significant than isotope 220 (4%), whilst isotope 219 is considered as negligible. Exposure to radon varies considerably from one region to another, depending on factors such as weather conditions, and underlying geology. Activity concentration can therefore vary by a factor of 10 or even a 100 from one period of time to the next and from one area to another. There are many ways of measuring the radon 222 activity concentration and the potential alpha energy concentration of its short-lived decay products. Measuring techniques fall into three categories: - spot measurement methods; continuous measurement; integrated measurement. The proposed ISO (International Organisation for Standardisation) document suggests guidelines for measuring radon222 activity concentration and the potential alpha energy concentration of its short-lived decay products in a free (environment) and confined (buildings) atmosphere. The target date for availability of

  4. Statistical analysis of the radon-222 potential of rocks in Virginia, U.S.A.

    USGS Publications Warehouse

    Brown, C. Erwin; Mose, D.G.; Mushrush, G.W.; Chrosniak, C.E.

    1992-01-01

    More than 3,200 indoor radon-222 (222Rn) measurements were made seasonally in an area of about 1,000 square kilometers of the Coastal Plain and Piedmont physiographic provinces in Virginia, U.S.A. Results of these measurements indicate that some geological units are associated, on the average, with twice as much indoor222Rn as other geological units, and that indoor222Rn varies seasonally. The Kruskal-Wallis test was used to test whether indoor222Rn concentrations for data gathered over the winter and summer seasons differ significantly by rock unit. The tests concluded that indoor222Rn concentrations for different rock units were not equal at the 5-percent significance level. The rocks associated with the highest median indoor222Rn concentration are specific rocks in the Mesozoic Culpeper basin, including shale and siltstone units with Jurassic diabase intrusives, and mica schists in the Piedmont physiographic province. The pre-Triassic Peters Creek Schist has the highest ranking in terms of indoor222Rn concentration. The rocks associated with the lowest indoor222Rn concentrations include coastal plain sediments, the Occoquan Granite, Falls Church Tonalite, Piney Branch Mafic and Ultramafic complex, and unnamed mafic and ultramafic inclusions, respectively. The rocks have been ranked according to observed222Rn concentration by transforming the average rank of indoor222Rn concentrations to z scores. ?? 1992 Springer-Verlag New York Inc.

  5. Radon (222Rn) in groundwater studies in two volcanic zones of central Mexico

    NASA Astrophysics Data System (ADS)

    Cortés, A.; Cardona, A.; Pérez-Quezadas, J.; Inguaggiato, S.; Vázquez-López, C.; Golzarri, J. I.; Espinosa, G.

    2013-07-01

    The distribution of radon (222Rn) concentrations in groundwater from two basins of volcanic origin is presented. Regions have different physiographic characteristics with fractured mafic/intermediate and felsic rocks. Samples were taken from deep wells and springs. Concentrations were field measured by two methods: i) scintillator, coupled to a photomultiplier, and ii) passive method, using Nuclear Track Detectors. Qualitatively, results of 222Rn measured with both techniques are comparable only when concentrations have values less than 1 Bq/l. For the Basin of Mexico City the data shows an average difference of 0.13 Bq/l. Results of 222Rn concentrations in 46 groundwater samples indicate that the data are below 11.1 Bq/l, with both methodologies. Low concentrations of 222Rn in the Basin of Mexico City are related to the mafic intermediate composition rocks such as basalt. The anomalies with high values are correlated with the transition zone between volcanic units and clays from ancient lakes. In San Luis Potosí 10 samples show an average of 4.2 Bq/l. These concentrations compared with those of the Basin of Mexico City are related to the composition of the felsic (rhyolite) volcanic rocks.

  6. Effective Dose of Radon 222 Bottled Water in Different Age Groups Humans: Bandar Abbas City, Iran.

    PubMed

    Fakhri, Yadolah; Mahvi, Amir Hossein; Langarizadeh, Ghazaleh; Zandsalimi, Yahya; Amirhajeloo, Leila Rasouli; Kargosha, Morteza; Moradi, Mahboobeh; Moradi, Bigard; Mirzaei, Maryam

    2016-01-01

    Radon 222 is a natural radioactive element with a half-life of 3.8 days. It is odorless and colorless as well as water-soluble. Consuming waters which contain high concentration of 222Rn would increase the effective dose received by different age groups. It would also be followed by an increased prevalence of cancer. In this research, 72 samples of the most commonly used bottled water in Bandar Abbas were collected in 3 consecutive months, May, June and July of 2013. Concentration 222Rn of was measured by radon-meter model RTM166-2. The effective dose received by the 4 age groups, male and female adults as well as children and infants was estimated using the equation proposed by UNSCEAR. The results revealed that the mean and range concentration of 222Rn in bottled waters were 641±9 Bq/m3 and 0-901 Bq/m3, respectively. The mean concentration of 222Rn in the well-known Marks followed this Zam Zam>Bishe>Koohrng>Dassani>Christal>Polour>Damavand>Sivan. Infants were observed to receive a higher effective dose than children. The highest and lowest effective dose received was found to belong to male adults and children, respectively. PMID:26383192

  7. Effective Dose of Radon 222 Bottled Water in Different Age Groups Humans: Bandar Abbas City, Iran.

    PubMed

    Fakhri, Yadolah; Mahvi, Amir Hossein; Langarizadeh, Ghazaleh; Zandsalimi, Yahya; Amirhajeloo, Leila Rasouli; Kargosha, Morteza; Moradi, Mahboobeh; Moradi, Bigard; Mirzaei, Maryam

    2015-06-04

    Radon 222 is a natural radioactive element with a half-life of 3.8 days. It is odorless and colorless as well as water-soluble. Consuming waters which contain high concentration of 222Rn would increase the effective dose received by different age groups. It would also be followed by an increased prevalence of cancer. In this research, 72 samples of the most commonly used bottled water in Bandar Abbas were collected in 3 consecutive months, May, June and July of 2013. Concentration 222Rn of was measured by radon-meter model RTM166-2. The effective dose received by the 4 age groups, male and female adults as well as children and infants was estimated using the equation proposed by UNSCEAR. The results revealed that the mean and range concentration of 222Rn in bottled waters were 641±9 Bq/m3 and 0-901 Bq/m3, respectively. The mean concentration of 222Rn in the well-known Marks followed this Zam Zam>Bishe>Koohrng>Dassani>Christal>Polour>Damavand>Sivan. Infants were observed to receive a higher effective dose than children. The highest and lowest effective dose received was found to belong to male adults and children, respectively.

  8. Effective Dose of Radon 222 Bottled Water in Different Age Groups Humans: Bandar Abbas City, Iran

    PubMed Central

    Fakhri, Yadolah; Mahvi, Amir Hossein; Langarizadeh, Ghazaleh; Zandsalimi, Yahya; Amirhajeloo, Leila Rasouli; Kargosha, Morteza; Moradi, Mahboobeh; Moradi, Bigard; Mirzaei, Maryam

    2016-01-01

    Radon 222 is a natural radioactive element with a half-life of 3.8 days. It is odorless and colorless as well as water-soluble. Consuming waters which contain high concentration of 222Rn would increase the effective dose received by different age groups. It would also be followed by an increased prevalence of cancer. In this research, 72 samples of the most commonly used bottled water in Bandar Abbas were collected in 3 consecutive months, May, June and July of 2013. Concentration 222Rn of was measured by radon-meter model RTM166-2. The effective dose received by the 4 age groups, male and female adults as well as children and infants was estimated using the equation proposed by UNSCEAR. The results revealed that the mean and range concentration of 222Rn in bottled waters were 641±9 Bq/m3 and 0-901 Bq/m3, respectively. The mean concentration of 222Rn in the well-known Marks followed this Zam Zam>Bishe>Koohrng>Dassani>Christal>Polour>Damavand>Sivan. Infants were observed to receive a higher effective dose than children. The highest and lowest effective dose received was found to belong to male adults and children, respectively. PMID:26383192

  9. Surface-deposition and Distribution of the Radon (222Rn and 220Rn) Decay Products Indoors

    NASA Astrophysics Data System (ADS)

    Espinosa, G.; Tommasino, Luigi

    The exposure to radon (222Rn and 220Rn) decay products is of great concern both in dwellings and workplaces. The model to estimate the lung dose refers to the deposition mechanisms and particle sizes. Unfortunately, most of the dose data available are based on the measurement of radon concentration and the concentration of radon decay products. These combined measurements are widely used in spite of the fact that accurate dose assessments require information on the particle deposition mechanisms and the spatial distribution of radon decay products indoors. Most of the airborne particles and/or radon decay products are deposited onto indoor surfaces, which deposition makes the radon decay products unavailable for inhalation. These deposition processes, if properly known, could be successfully exploited to reduce the exposure to radon decay products. In spite of the importance of the surface deposition of the radon decay products, both for the correct evaluation of the dose and for reducing the exposure, little or no efforts have been made to investigate these deposition processes. Recently, two parallel investigations have been carried out in Rome and at Universidad Nacional Autónoma de México (UNAM) in Mexico City respectively, which address the issue of the surface-deposited radon decay products. Even though these investigations have been carried independently, they complement one another. It is with these considerations in mind that it was decided to report both investigations in the same paper.

  10. Investigation of some factors affecting on release of radon-222 from phosphogypsum waste associated with phosphate ore processing.

    PubMed

    Hilal, M A; El Afifi, E M; Nayl, A A

    2015-07-01

    The aim of this study is oriented to investigate the influence of some physicochemical factors such as radium distribution, grain size, moisture content and chemical constituents on releases of radon-222 from the accumulated phosphogypsum (PG) waste. The emanation fraction, activity concentration in the pore and the surface exhalation rate of radon-222 in the bulk PG waste are 34.5 ± 0.3%, 238.6 ± 7.8 kBq m(-3) and 213 ± 6.9 mBq m(-2) s(-1), respectively. These values were varied and enhanced slightly in the fine grain sizes (F1 < 0.125 mm) by a factor of 1.05 folds compared to the bulk residue. It was also found that release of radon from residue PG waste was controlled positively by radium (Ra-226), calcium (CaSO4) and strontium (SrO). About 67% of radon release attributed to the grain size below 0.5 mm, while 33% due to the large grain size above 0.5 mm. The emanation fraction of Rn-222 is increased with moisture content and the maximum emanation is ∼43% of moisture of 3-8%. It reduced slowly with the continuous increase in moisture till 20%. Due to PG waste in situ can be enhancing the background to the surround workers and/or public. Therefore, the environmental negative impacts due to release of Rn-222 can be minimized by legislation to restrict its civil uses, or increasing its moisture to ∼10%, or by the particle size separation of the fine fraction containing the high levels of Ra-226 followed by a suitable chemical treatment or disposal; whereas the low release amount can be diluted and used in cement industry, roads or dam construction. PMID:25863719

  11. Investigation of some factors affecting on release of radon-222 from phosphogypsum waste associated with phosphate ore processing.

    PubMed

    Hilal, M A; El Afifi, E M; Nayl, A A

    2015-07-01

    The aim of this study is oriented to investigate the influence of some physicochemical factors such as radium distribution, grain size, moisture content and chemical constituents on releases of radon-222 from the accumulated phosphogypsum (PG) waste. The emanation fraction, activity concentration in the pore and the surface exhalation rate of radon-222 in the bulk PG waste are 34.5 ± 0.3%, 238.6 ± 7.8 kBq m(-3) and 213 ± 6.9 mBq m(-2) s(-1), respectively. These values were varied and enhanced slightly in the fine grain sizes (F1 < 0.125 mm) by a factor of 1.05 folds compared to the bulk residue. It was also found that release of radon from residue PG waste was controlled positively by radium (Ra-226), calcium (CaSO4) and strontium (SrO). About 67% of radon release attributed to the grain size below 0.5 mm, while 33% due to the large grain size above 0.5 mm. The emanation fraction of Rn-222 is increased with moisture content and the maximum emanation is ∼43% of moisture of 3-8%. It reduced slowly with the continuous increase in moisture till 20%. Due to PG waste in situ can be enhancing the background to the surround workers and/or public. Therefore, the environmental negative impacts due to release of Rn-222 can be minimized by legislation to restrict its civil uses, or increasing its moisture to ∼10%, or by the particle size separation of the fine fraction containing the high levels of Ra-226 followed by a suitable chemical treatment or disposal; whereas the low release amount can be diluted and used in cement industry, roads or dam construction.

  12. Estimating the importance of factors influencing the radon-222 flux from building walls.

    PubMed

    Girault, Frédéric; Perrier, Frédéric

    2012-09-01

    Radiation hazard in dwellings is dominated by the contribution of radon-222 released from soil and bedrock, but the contribution of building materials can also be important. Using a simple air mixing model in a 2-story house with an attic and a basement, it is estimated that a significant risk arises when the Wall Radon exhalation Flux (WRF) exceeds 10×10(-3) Bq·m(-2)·s(-1). WRF is studied using a multiphase advection-diffusion 3-layer analytical model with advective flow, possibly induced by a pressure deficit inside the house compared with the outside atmosphere. To first order, in most circumstances, the WRF is proportional to the wall thickness and to the radon source term, the effective radium concentration EC(Ra), which is the product of the radium-226 concentration by the emanation coefficient E. The WRF decreases with increasing material porosity and exhibits a maximum for water saturation of about 50%. For EC(Ra)=10 Bq·kg(-1), in many instances, WRF is larger than 10×10(-3) Bq·m(-2)·s(-1) and, therefore, EC(Ra)=10 Bq·kg(-1) can be considered as the typical limit not to be exceeded by building materials. An upper limit of the WRF is obtained in the purely advective regime, independent of porosity or moisture content, which can thus be used as a robust safety guideline. The sensitivity of WRF to temperature, due to the temperature sensitivity of EC(Ra) or the temperature sensitivity of radon Henry constant can be larger than 5% for the seasonal variation in the presence of slight pressure deficit. The temperature sensitivity of EC(Ra) is the dominant effect, except for moist walls. Temperature and moisture variation effects on the WRF potentially can account for most observed seasonal variations of radon concentration in houses, in addition to seasonal changes of air exchange, suggesting that the contribution of walls should be considered when designing remediation strategies and studied with dedicated experiments. PMID:22796415

  13. Radon-222 in groundwater of the Long Valley caldera, California

    NASA Astrophysics Data System (ADS)

    Wollenberg, H. A.; Smith, A. R.; Mosier, D. F.; Flexser, S.; Clark, M.

    1984-03-01

    In the Long Valley caldera, where seismicity has continued essentially uninterrupted since mid-1980 and uplift is documented, samples of water from hot, warm, and cold springs have been collected since September, 1982, and their222Rn concentrations analyzed. Concurrently, rocks encompassing the hydrologic systems feeding the springs were analyzed for their radioelement contents, because their uranium is the ultimate source of the222Rn in the water. The222Rn concentration in the springs varies inversely with their temperature and specific conductance. High concentrations (1500 to 2500 picocuries per liter) occur in dilute cold springs on the margins of the caldera, while low contents (12 to 25 pCi/l) occur in hot to boiling springs. Springwater radon concentrations also correlate slightly with the uranium content of the encompassing rocks. A continuous monitoring system was installed in August, 1983, at a spring issuing from basalt, to provide hourly records of radon concentration. A gamma detector is submerged in a natural pool, and we have observed that the radioactivity measured in this manner is due almost entirely to the222Rn concentration of the water. Initial operation shows diurnal and semidiurnal variations in the222Rn concentration of the springwater that are ascribed to earth tides, suggesting that those variations are responding to small changes in stress in the rocks encompassing the hydrologic system.

  14. Activity of radon (222Rn) in the lower atmospheric surface layer of a typical rural site in south India

    NASA Astrophysics Data System (ADS)

    Kumar, K. Charan; Prasad, T. Rajendra; Ratnam, M. Venkat; Nagaraja, Kamsali

    2016-09-01

    Analysis of one year measurements of in situ radon (222Rn) and its progenies along with surface air temperature, relative humidity and pressure near to the Earth's surface has been carried out for the first time at the National Atmospheric Research Laboratory (NARL, 13.5∘N and 79.2∘E) located in a rural site in Gadanki, south India. The dataset was analysed to understand the behaviour of radon in relation to the surface air temperature and relative humidity at a rural site. It was observed that over a period of the 24 hours in a day, the activity of radon and its progenies reaches a peak in the morning hours followed by a remarkable decrease in the afternoon hours. Relatively, a higher concentration of radon was observed at NARL during fair weather days, and this can be attributed to the presence of rocky hills and dense vegetation surrounding the site. The high negative correlation between surface air temperature and activity of radon (R = - 0.70, on an annual scale) suggests that dynamical removal of radon due to increased vertical mixing is one of the most important controlling processes of the radon accumulation in the atmospheric surface layer. The annual averaged activity of radon was found to be 12.01±0.66 Bq m-3 and 4.25±0.18 Bq m-3 for its progenies, in the study period.

  15. Seasonal variations of natural ventilation and radon-222 exhalation in a slightly rising dead-end tunnel.

    PubMed

    Perrier, Frédéric; Richon, Patrick; Gautam, Umesh; Tiwari, Dilli Ram; Shrestha, Prithvi; Sapkota, Soma Nath

    2007-01-01

    The concentration activity of radon-222 has been monitored, with some interruptions, from 1997 to 2005 in the end section of a slightly rising, dead-end, 38-m long tunnel located in the Phulchoki hill, near Kathmandu, Nepal. While a high concentration varying from 6 x 10(3) Bq m(-3) to 10 x 10(3) Bq m(-3) is observed from May to September (rainy summer season), the concentration remains at a low level of about 200 Bq m(-3) from October to March (dry winter season). This reduction of radon concentration is associated with natural ventilation of the tunnel, which, contrary to expectations for a rising tunnel, takes place mainly from October to March when the outside air temperature drops below the average tunnel temperature. This interpretation is supported by temperature measurements in the atmosphere of the tunnel, a few meters away from the entrance. The temporal variations of the diurnal amplitude of this temperature indeed follow the ventilation rate deduced from the radon measurements. In the absence of significant ventilation (summer season), the radon exhalation flux at the rock surface into the tunnel atmosphere can be inferred; it exhibits a yearly variation with additional transient reductions associated with heavy rainfall, likely to be due to water infiltration. No effect of atmospheric pressure variations on the radon concentration is observed in this tunnel. This experiment illustrates how small differences in the location and geometry of a tunnel can lead to vastly different behaviours of the radon concentration versus time. This observation has consequences for the estimation of the dose rate and the practicability of radon monitoring for tectonic purposes in underground environments. PMID:17761360

  16. Seasonal variations of natural ventilation and radon-222 exhalation in a slightly rising dead-end tunnel.

    PubMed

    Perrier, Frédéric; Richon, Patrick; Gautam, Umesh; Tiwari, Dilli Ram; Shrestha, Prithvi; Sapkota, Soma Nath

    2007-01-01

    The concentration activity of radon-222 has been monitored, with some interruptions, from 1997 to 2005 in the end section of a slightly rising, dead-end, 38-m long tunnel located in the Phulchoki hill, near Kathmandu, Nepal. While a high concentration varying from 6 x 10(3) Bq m(-3) to 10 x 10(3) Bq m(-3) is observed from May to September (rainy summer season), the concentration remains at a low level of about 200 Bq m(-3) from October to March (dry winter season). This reduction of radon concentration is associated with natural ventilation of the tunnel, which, contrary to expectations for a rising tunnel, takes place mainly from October to March when the outside air temperature drops below the average tunnel temperature. This interpretation is supported by temperature measurements in the atmosphere of the tunnel, a few meters away from the entrance. The temporal variations of the diurnal amplitude of this temperature indeed follow the ventilation rate deduced from the radon measurements. In the absence of significant ventilation (summer season), the radon exhalation flux at the rock surface into the tunnel atmosphere can be inferred; it exhibits a yearly variation with additional transient reductions associated with heavy rainfall, likely to be due to water infiltration. No effect of atmospheric pressure variations on the radon concentration is observed in this tunnel. This experiment illustrates how small differences in the location and geometry of a tunnel can lead to vastly different behaviours of the radon concentration versus time. This observation has consequences for the estimation of the dose rate and the practicability of radon monitoring for tectonic purposes in underground environments.

  17. Radon-222 exhalation from open ground on and around a uranium mine in the wet-dry tropics.

    PubMed

    Lawrence, Cameron E; Akber, Riaz A; Bollhöfer, Andreas; Martin, Paul

    2009-01-01

    Radon-222 exhalation from the ground surface depends upon a number of variables such as the 226Ra activity concentration and its distribution in soil grains; soil grain size; soil porosity, temperature and moisture; atmospheric pressure, rainfall and temperature. In this study, 222Rn exhalation flux density measurements within and around the Ranger uranium mine in northern Australia were performed to investigate the effect of these variables within a tropical region. Measurements were taken at the waste rock dumps, ore stockpiles, mine pits, and at sites where effluent water with elevated 226Ra concentration has been spray irrigated over land, as well as at sites outside the mine. The sites selected represented a variety of geomorphic regions ranging from uranium-bearing rocks to ambient soils. Generally, wet season rains reduced 222Rn exhalation but at a few sites the onset of rains caused a step rise in exhalation flux densities. The results show that parameters such as 226Ra activity concentration, soil grain size and soil porosity have a marked effect on 222Rn flux densities. For similar geomorphic sites, 226Ra activity concentration is a dominant factor, but soil grain size and porosity also influence 222Rn exhalation. Surfaces with vegetation showed higher exhalation flux densities than their barren counterparts, perhaps because the associated root structure increases soil porosity and moisture retention. Repeated measurements over one year at eight sites enabled an analysis of precipitation and soil moisture effects on 222Rn exhalation. Soil moisture depth profiles varied both between seasons and at different times during the wet season, indicating that factors such as duration, intensity and time between precipitation events can influence 222Rn flux densities considerably.

  18. Mapping indoor radon-222 in Denmark: design and test of the statistical model used in the second nationwide survey.

    PubMed

    Andersen, C E; Ulbak, K; Damkjaer, A; Kirkegaard, P; Gravesen, P

    2001-05-14

    In Denmark, a new survey of indoor radon-222 has been carried out, 1-year alpha track measurements (CR-39) have been made in 3019 single-family houses. There are from 3 to 23 house measurements in each of the 275 municipalities. Within each municipality, houses have been selected randomly. One important outcome of the survey is the prediction of the fraction of houses in each municipality with an annual average radon concentration above 200 Bq m(-3). To obtain the most accurate estimate and to assess the associated uncertainties, a statistical model has been developed. The purpose of this paper is to describe the design of this model, and to report results of model tests. The model is based on a transformation of the data to normality and on analytical (conditionally) unbiased estimators of the quantities of interest. Bayesian statistics are used to minimize the effect of small sample size. In each municipality, the correction is dependent on the fraction of area where sand and gravel is a dominating surface geology. The uncertainty analysis is done with a Monte-Carlo technique. It is demonstrated that the weighted sum of all municipality model estimates of fractions above 200 Bq m(-3) (3.9% with 95%-confidence interval = [3.4,4.5]) is consistent with the weighted sum of the observations for Denmark taken as a whole (4.6% with 95%-confidence interval = [3.8,5.6]). The total number of single-family houses within each municipality is used as weight. Model estimates are also found to be consistent with observations at the level of individual counties. These typically include a few hundred house measurements. These tests indicate that the model is well suited for its purpose.

  19. A simulation of the transport and fate of radon-222 derived from thorium-230 low-level waste in the near-surface zone of the Radioactive Waste Management Site in Area 5 of the Nevada Test Site

    SciTech Connect

    Lindstrom, F.T.; Cawlfield, D.E.; Donahue, M.E.; Emer, D.F.; Shott, G.J.

    1993-12-01

    US Department of Energy (DOE) Order 5820.2A (DOE, 1988) requires performance assessments on all new and existing low-level radioactive waste (LLW) disposal sites. An integral part of performance assessment is estimating the fluxes of radioactive gases such as radon-220 and radon-222. Data needs pointed out by mathematical models drive site characterization. They provide a logical means of performing the required flux estimations. Thorium-230 waste, consisting largely of thorium hydroxide and thorium oxides, has been approved for disposal in shallow trenches and pits at the LLW Radioactive Waste Management Site in Area 5 of the Nevada Test Site. A sophisticated gas transport model, CASCADR8 (Lindstrom et al., 1992b), was used to simulate the transport and fate of radon-222 from its source of origin, nine feet below a closure cap of native soil, through the dry alluvial earth, to its point of release into the atmosphere. CASCADR8 is an M-chain gas-phase radionuclide transport and fate model. It has been tailored to the site-specific needs of the dry desert environment of southern Nevada. It is based on the mass balance principle for each radionuclide and uses gas-phase diffusion as well as barometric pressure-induced advection as its main modes of transport. CASCADR8 uses both reversible and irreversible sorption kinetic rules as well as the usual classical Bateman (1910) M-chain decay rules for its kinetic processes. Worst case radon-222 gas-phase concentrations, as well as surface fluxes, were estimated over 40 days. The maximum flux was then used in an exposure assessment model to estimate the total annual dose equivalent received by a person residing in a standard 2500-square-foot house with 10-foot walls. Results are described.

  20. Groundwater Discharge into Intermittently Closed and Open Lakes and/or Lagoons (ICOLLs) via Radon-222

    NASA Astrophysics Data System (ADS)

    Sadat-Noori, M.; Santos, I. R.; Tait, D. R.; McMahon, A.; Kadel, S.; Maher, D. T.

    2015-12-01

    Intermittently Closed and Open Lakes and Lagoons (ICOLLs) are brackish coastal water bodies with an intermittent connection to the ocean that is closed periodically due to the accumulation of marine sediment forming an entrance berm. ICOLLs have dynamic coastal systems that may be vulnerable to minor changes in catchment hydrology. However, little is known regarding the impacts of groundwater on the hydrological cycles of ICOLLs. The relative contribution of rainfall versus groundwater discharge in two ICOLLs (Welsby, and Mermaid Lagoon) and a nearby wetland (South Welsby Lagoon) located on Bribie Island (Australia) were investigated using radon (222Rn) as natural geochemical groundwater tracer. Four seasonal surveys were undertaken to quantify the temporal and spatial groundwater dynamics of the ICOLLs. Radon contour maps revealed temporal and spatial changes over the study period. The estimated groundwater discharge rates from a radon-mass balance were 3.4±3.1, 7.3±9.8 and 2.6±3.8 cm d-1 in Weslby, South Weslby and Mermaid Lagoons, respectively. These values are at least 8-fold greater than rainfall (1420 mm per year, or 0.4 cm d-1). Assuming very minor surface water flows (not perceived during field surveys), this demonstrates that these systems are groundwater-dominated and their hydrology can be influenced by regional changes in groundwater level.

  1. Numerical modelling of radon-222 entry into houses: an outline of techniques and results.

    PubMed

    Andersen, C E

    2001-05-14

    Numerical modelling is a powerful tool for studies of soil gas and radon-222 entry into houses. It is the purpose of this paper to review some main techniques and results. In the past, modelling has focused on Darcy flow of soil gas (driven by indoor-outdoor pressure differences) and combined diffusive and advective transport of radon. Models of different complexity have been used. The simpler ones are finite-difference models with one or two spatial dimensions. The more complex models allow for full three-dimensional and time dependency. Advanced features include: soil heterogeneity, anisotropy, fractures, moisture, non-uniform soil temperature, non-Darcy flow of gas, and flow caused by changes in the atmospheric pressure. Numerical models can be used to estimate the importance of specific factors for radon entry. Models are also helpful when results obtained in special laboratory or test structure experiments need to be extrapolated to more general situations (e.g. to real houses or even to other soil-gas pollutants). Finally, models provide a cost-effective test bench for improved designs of radon prevention systems. The paper includes a summary of transport equations and boundary conditions. As an illustrative example, radon entry is calculated for a standard slab-on-grade house.

  2. [Contents of radon 222Rn in drinking water of Sweradów Zdrój and Czerniawa Zdrój].

    PubMed

    Pachocki, K A; Gorzkowski, B; Wilejczyk, E; Smoter, J

    2000-01-01

    Radon-222 concentration in surface water, wells and tap water in Swieradów Zdrój and in Czerniawa Zdrój has been quantitative determined. The measurements were performed using the alpha liquid scintillation counting method. Radon arithmetic mean for water of individual wells in Swieradów Zdrój was found to be 438.5 Bq/l within the range between 42 Bq/ and 1095 Bq/l. The appropriate mean value for water of individual wells Czerniawa Zdrój was 165 Bq/l within the range from 25.8 Bq/l and 402.4 Bq/l. Waterworks in Czerniawa Zdrój is supplied with the surface water in which the radon concentration is low (about 2 Bq/l). Water works in Swieradów Zdrój is supplied with the mixed water consisting from the surface water, which main characteristic is low radon concentration (below 11 Bq/l), and from artesian well and mine gallery water with the radon concentration from 321 Bq/l to 464 Bq/l in it. This water is mixed in various ratios and therefore the radon concentration in it was within 4 Bq/l and 79 Bq/l.

  3. Radon (222Rn) in ground water of fractured rocks: A diffusion/ion exchange model

    USGS Publications Warehouse

    Wood, W.W.; Kraemer, T.F.; Shapiro, A.

    2004-01-01

    Ground waters from fractured igneous and high-grade sialic metamorphic rocks frequently have elevated activity of dissolved radon (222Rn). A chemically based model is proposed whereby radium (226Ra) from the decay of uranium (238U) diffuses through the primary porosity of the rock to the water-transmitting fracture where it is sorbed on weathering products. Sorption of 226Ra on the fracture surface maintains an activity gradient in the rock matrix, ensuring a continuous supply of 226Ra to fracture surfaces. As a result of the relatively long half-life of 226Ra (1601 years), significant activity can accumulate on fracture surfaces. The proximity of this sorbed 226Ra to the active ground water flow system allows its decay progeny 222Rn to enter directly into the water. Laboratory analyses of primary porosity and diffusion coefficients of the rock matrix, radon emanation, and ion exchange at fracture surfaces are consistent with the requirements of a diffusion/ion- exchange model. A dipole-brine injection/withdrawal experiment conducted between bedrock boreholes in the high-grade metamorphic and granite rocks at the Hubbard Brook Experimental Forest, Grafton County, New Hampshire, United States (42??56???N, 71??43???W) shows a large activity of 226Ra exchanged from fracture surfaces by a magnesium brine. The 226Ra activity removed by the exchange process is 34 times greater than that of 238U activity. These observations are consistent with the diffusion/ion-exchange model. Elutriate isotopic ratios of 223Ra/226Ra and 238U/226Ra are also consistent with the proposed chemically based diffusion/ion-exchange model.

  4. Radon-222 activity flux measurement using activated charcoal canisters: revisiting the methodology.

    PubMed

    Alharbi, Sami H; Akber, Riaz A

    2014-03-01

    The measurement of radon ((222)Rn) activity flux using activated charcoal canisters was examined to investigate the distribution of the adsorbed (222)Rn in the charcoal bed and the relationship between (222)Rn activity flux and exposure time. The activity flux of (222)Rn from five sources of varying strengths was measured for exposure times of one, two, three, five, seven, 10, and 14 days. The distribution of the adsorbed (222)Rn in the charcoal bed was obtained by dividing the bed into six layers and counting each layer separately after the exposure. (222)Rn activity decreased in the layers that were away from the exposed surface. Nevertheless, the results demonstrated that only a small correction might be required in the actual application of charcoal canisters for activity flux measurement, where calibration standards were often prepared by the uniform mixing of radium ((226)Ra) in the matrix. This was because the diffusion of (222)Rn in the charcoal bed and the detection efficiency as a function of the charcoal depth tended to counterbalance each other. The influence of exposure time on the measured (222)Rn activity flux was observed in two situations of the canister exposure layout: (a) canister sealed to an open bed of the material and (b) canister sealed over a jar containing the material. The measured (222)Rn activity flux decreased as the exposure time increased. The change in the former situation was significant with an exponential decrease as the exposure time increased. In the latter case, lesser reduction was noticed in the observed activity flux with respect to exposure time. This reduction might have been related to certain factors, such as absorption site saturation or the back diffusion of (222)Rn gas occurring at the canister-soil interface.

  5. Quantification of Submarine Groundwater Discharge Using a Radon (222-Rn) Mass Balance and Hydrogeological Modelling

    NASA Astrophysics Data System (ADS)

    Petermann, Eric; Stollberg, Reiner; Scholten, Jan; Knöller, Kay; Schubert, Michael

    2016-04-01

    Apart from river and surface water runoff subsurface discharge of groundwater plays a key role in coastal water and matter budgets. Two major forms of submarine groundwater discharge (SGD) can be distinguished: (i) pure freshwater discharge from continental aquifers that are connected to the coastal sea driven by a positive hydraulic gradient (fresh SGD) and (ii) re-circulation of seawater that has penetrated permeable coastal sediments (re-circulated SGD), e.g. driven by tidal pumping. The localization of SGD zones and the quantification of SGD fluxes is of high interest for coastal water management due to potential threats related to SGD, namely (i) the detrimental impact of discharging nutrient- or contaminant-laden groundwater on coastal seawater quality, an aspect that is of relevance along coastlines which are impacted by agriculture, industry or intense urbanization, and (ii) the loss of freshwater to the ocean, an issue that is of major relevance in all coastal areas with (seasonally) limited freshwater availability. In this work, we discuss estimates for the total (fresh + re-circulated) SGD fluxes derived from a mass balance of the radioactive noble gas radon (222-Rn) with estimates of fresh SGD fluxes derived by hydrogeological modelling. The precision of the mass balance results depends on the adequate determination of the mass balance source and sink terms. These terms are calculated based on field observations of environmental tracers (salinity, δ18O, 222-Rn, 223-Ra, 224-Ra, 226-Ra) in seawater and porewater, as well as on meteorological data. The numerical hydrogeological model estimates groundwater flow based on groundwater monitoring data, river flow data, groundwater recharge estimates, tidal dynamics, and density effects along the freshwater/seawater interface. We compare these two independent methodological approaches of SGD flux estimation, discuss results regarding their relevance for the regional water balance and reason the implications of

  6. Radon (222Rn) in ground water of fractured rocks: a diffusion/ion exchange model.

    PubMed

    Wood, Warren W; Kraemer, Thomas F; Shapiro, Allen

    2004-01-01

    Ground waters from fractured igneous and high-grade sialic metamorphic rocks frequently have elevated activity of dissolved radon (222Rn). A chemically based model is proposed whereby radium (226Ra) from the decay of uranium (238U) diffuses through the primary porosity of the rock to the water-transmitting fracture where it is sorbed on weathering products. Sorption of 226Ra on the fracture surface maintains an activity gradient in the rock matrix, ensuring a continuous supply of 226Ra to fracture surfaces. As a result of the relatively long half-life of 226Ra (1601 years), significant activity can accumulate on fracture surfaces. The proximity of this sorbed 226Ra to the active ground water flow system allows its decay progeny 222Rn to enter directly into the water. Laboratory analyses of primary porosity and diffusion coefficients of the rock matrix, radon emanation, and ion exchange at fracture surfaces are consistent with the requirements of a diffusion/ion-exchange model. A dipole-brine injection/withdrawal experiment conducted between bedrock boreholes in the high-grade metamorphic and granite rocks at the Hubbard Brook Experimental Forest, Grafton County, New Hampshire, United States (42 degrees 56'N, 71 degrees 43'W) shows a large activity of 226Ra exchanged from fracture surfaces by a magnesium brine. The 226Ra activity removed by the exchange process is 34 times greater than that of 238U activity. These observations are consistent with the diffusion/ion-exchange model. Elutriate isotopic ratios of 223Ra/226Ra and 238U/226Ra are also consistent with the proposed chemically based diffusion/ion-exchange model. PMID:15318778

  7. Radon (222Rn) in ground water of fractured rocks: a diffusion/ion exchange model.

    PubMed

    Wood, Warren W; Kraemer, Thomas F; Shapiro, Allen

    2004-01-01

    Ground waters from fractured igneous and high-grade sialic metamorphic rocks frequently have elevated activity of dissolved radon (222Rn). A chemically based model is proposed whereby radium (226Ra) from the decay of uranium (238U) diffuses through the primary porosity of the rock to the water-transmitting fracture where it is sorbed on weathering products. Sorption of 226Ra on the fracture surface maintains an activity gradient in the rock matrix, ensuring a continuous supply of 226Ra to fracture surfaces. As a result of the relatively long half-life of 226Ra (1601 years), significant activity can accumulate on fracture surfaces. The proximity of this sorbed 226Ra to the active ground water flow system allows its decay progeny 222Rn to enter directly into the water. Laboratory analyses of primary porosity and diffusion coefficients of the rock matrix, radon emanation, and ion exchange at fracture surfaces are consistent with the requirements of a diffusion/ion-exchange model. A dipole-brine injection/withdrawal experiment conducted between bedrock boreholes in the high-grade metamorphic and granite rocks at the Hubbard Brook Experimental Forest, Grafton County, New Hampshire, United States (42 degrees 56'N, 71 degrees 43'W) shows a large activity of 226Ra exchanged from fracture surfaces by a magnesium brine. The 226Ra activity removed by the exchange process is 34 times greater than that of 238U activity. These observations are consistent with the diffusion/ion-exchange model. Elutriate isotopic ratios of 223Ra/226Ra and 238U/226Ra are also consistent with the proposed chemically based diffusion/ion-exchange model.

  8. Results from the Lunar Prospector Alpha Particle Spectrometer: Detection of Radon-222 Over Craters Aristarchus and Kepler

    NASA Astrophysics Data System (ADS)

    Lawson, S. L.; Feldman, W. C.; Lawrence, D. J.; Moore, K. R.; Belian, R. D.; Maurice, S.; Binder, A. B.

    2001-11-01

    The Lunar Prospector Alpha Particle Spectrometer (LP APS) searched for lunar surface gas release events and mapped their distribution by detecting alpha particles produced by the decay of gaseous radon-222 (5.5 MeV, 3.8 day half-life), solid polonium-218 (6.0 MeV, 3 minute half-life), and solid polonium-210 (5.3 MeV, 138 day half-life, but held up in production by the 21 year half-life of lead-210). These three nuclides are radioactive daughters from the decay of uranium-238. Radon reaches the lunar surface either at areas of high soil porosity or where fissures release the trapped gases in which radon is entrained. We have examined APS data within +/- 45 degrees of the equator acquired during periods of low interplanetary alpha particle flux. The spectra were summed over all LP mapping cycles when the instrument was turned on (approximately 229 days over 16 months). To yield lunar alpha particle maps, we summed over a 0.2 MeV energy range centered on each of the three alpha particle energies noted above. The LP APS found only a faint indication of alpha particles resulting from the decay of polonium-218 and only a marginal detection of alpha particles from polonium-210. However, our radon-222 alpha particle map indicates that radon gas is presently emanating from the vicinity of craters Aristarchus and Kepler. The LP gamma-ray spectrometer, which effectively has significantly higher spatial resolution than the APS, identified thorium enrichments at these two craters. Thorium and uranium are both incompatible elements whose lunar surface abundances are highly correlated; thus, it is likely that the radon-222 alpha particles measured using the LP APS originate from Kepler and Aristarchus. Our detection of radon over Aristarchus is consistent with the results of the Apollo 15 APS.

  9. A case study of radon-222 transport from continental North-East Asia to the Japanese islands in winter by numerical analysis.

    PubMed

    Sakashita, T; Doi, M; Nakamura, Y; Iida, T

    2004-01-01

    A case study of the regional transport ( approximately 3000 km) of radon-222 ((222)Rn) from continental North-East Asia to the Japanese islands was performed by numerical analysis using five separate source areas (South, Middle and North China, Russia and Korea), while a seasonal northwest wind blew over the Japan Sea. The results for three periods (Term I: 16-18, Term II: 22-25 and Term III: 27-28 in December 1990) were compared with concentrations measured at the Kanazawa site (near the coast of the Japan Sea facing the seasonal wind) and the Nagoya site (overland and downwind on the shores of the Pacific Ocean). Most of the (222)Rn at the Kanazawa site was calculated to come from North China and Korea in Term I, Middle China, North China, and Korea in Term II, and Russia and Korea in Term III. The considerable differences in the origins of (222)Rn emanated from the continent were estimated between Terms I, II and III, even though the similar northwest wind was dominant over the Japan Sea. A contour line analysis indicated movement of (222)Rn emanated from Middle China in a northerly direction first and then a southeasterly direction, resulting from low pressure. The results suggest that the low-pressure systems play an important role in the transport of (222)Rn in North-East Asia.

  10. TRENDS IN RURAL SULFUR CONCENTRATIONS

    EPA Science Inventory

    This paper presents an analysis of regional trends in atmospheric concentrations in sulfur dioxide (502) and particulate sulfate (50~- ) at rural monitoring sites in the Clean Air Act Status and Trends Monitoring Network (CAsTNet) from 1990 to 1999. A two-stage approach is used t...

  11. Assessment of Karst Spring Features in a typical Mediterranean fluvial landscape with an Interdisciplinary Investigation nased on Radon-222 as an Environmental Indicator. The case study of the Bussento River basin (Campania region, Southern Italy).

    NASA Astrophysics Data System (ADS)

    Cuomo, A.; Guadagnuolo, D.; Guida, D.; Guida, M.; Knoeller, K.; Schubert, M.; Siervo, V.

    2012-04-01

    Karst aquifers provide 25% of the overall drinking water resources to the world's population and sustain aquatic life in most fluvial systems, providing several ecological services to human beings, although, because of their complex links between surface and groundwater, turn out to be very vulnerable to contamination and pollution. Hydrological assessment of karst systems reveals to be extremely complex and difficult and requires a stepwise multi-tracers approach. This work describes some of the most relevant findings obtained from the implementation of an interdisciplinary approach based on the use of Environmental Tracers, consisting of Naturally Occurring Radionuclides like Radon-222 (referred to as Radon), for the investigation of Groundwater/Surface water Interaction (GSI) processes in fluvial water bodies. In particular, Radon activity concentration measurement data having been collected from streamflow and instream springs during monthly field campaigns performed in a typical Mediterranean karst river basin: the Bussento river system (Campania region, Southern Italy). The general task has been to investigate the complex interactions and exchanges between streamflow and groundwater in a fluvial water body, at scales that are imperceptible to standard hydrological and hydraulic analyses. The Bussento River basin has been chosen as a study case for the following features of extreme relevance: Its location inside the Cilento and Vallo di Diano National Park, its inclusion of a WWF Nature Reserve, it represents a remarkable Drinking Water resource for the territory and last but not least its system includes Submarine Groundwater Discharges (SGD) to the Policastro Gulf. All these issues causes, therefore, that the management of its relevant water resources requires not only groundwater protection for domestic drinking use, but also riverine wildlife preservation and coastal water quality maintenance. As a support for hydro-geomorphological and hydrological

  12. Using Radon-222 as a Naturally Occurring Tracer to investigate the streamflow-groundwater interactions in a typical Mediterranean fluvial-karst landscape: the interdisciplinary case study of the Bussento river (Campania region, Southern Italy).

    NASA Astrophysics Data System (ADS)

    Cuomo, Albina; Guida, Michele; Guida, Domenico; Villani, Paolo; Guadagnuolo, Davide; Longobardi, Antonia; Siervo, Vincenzo

    2010-05-01

    Karst aquifers provide 25% of the overall drinking water resources to the world's population and sustain aquatic life in most fluvial systems, providing several ecological services to human beings, although, because of their complex links between surface and groundwater, turn out to be very vulnerable to contamination and pollution. This paper describes the preliminary findings from Radon-222 activity concentration measurement data collected in streamflow and instream springs during monthly field campaigns, performed from September 2007 to December 2008, in a typical Mediterranean karst river: the Bussento river (Campania region, Southern Italy). The general aim is to investigate the complex interactions and exchanges between streamflow and groundwater, at scales that are imperceptible to standard hydrological and hydraulic analyses. In fact, the study area is located inside the Cilento and Vallo di Diano National Park and, therefore, the management of its relevant water resources requires not only groundwater protection for domestic drinking use, but also riverine wildlife preservation and coastal water quality maintenance. As a support for hydro-geomorphological and hydrological modelling for planning tasks, in application of the European Water Framework Directive (EWFD), a Bussento River Monitoring System (BRMS) has been built, at basin, segment and reach scale. Experimental data about 222Rn concentrations, in addition to physical-chemical and streamflow rate, have been acquired and managed from BRMS selected stations, sampling the streamflow and inflow spring waters by means of the Radon-in-Air analyzer, RAD7, together with the Radon-in-water accessories, Radon Water Probe and RAD7H2O (DURRIDGE Co. Inc.), for continuous and batch sampling measurements, respectively. During preliminary surveys, appropriate sampling procedures and measurement protocols have been tested, taking into account the different local hydrogeological and hydrological situations occurring

  13. Activities and summary statistics of radon-222 in stream- and ground-water samples, Owl Creek basin, north-central Wyoming, September 1991 through March 1992

    USGS Publications Warehouse

    Ogle, K.M.; Lee, R.W.

    1994-01-01

    Radon-222 activity was measured for 27 water samples from streams, an alluvial aquifer, bedrock aquifers, and a geothermal system, in and near the 510-square mile area of Owl Creek Basin, north- central Wyoming. Summary statistics of the radon- 222 activities are compiled. For 16 stream-water samples, the arithmetic mean radon-222 activity was 20 pCi/L (picocuries per liter), geometric mean activity was 7 pCi/L, harmonic mean activity was 2 pCi/L and median activity was 8 pCi/L. The standard deviation of the arithmetic mean is 29 pCi/L. The activities in the stream-water samples ranged from 0.4 to 97 pCi/L. The histogram of stream-water samples is left-skewed when compared to a normal distribution. For 11 ground-water samples, the arithmetic mean radon- 222 activity was 486 pCi/L, geometric mean activity was 280 pCi/L, harmonic mean activity was 130 pCi/L and median activity was 373 pCi/L. The standard deviation of the arithmetic mean is 500 pCi/L. The activity in the ground-water samples ranged from 25 to 1,704 pCi/L. The histogram of ground-water samples is left-skewed when compared to a normal distribution. (USGS)

  14. TRENDS IN RURAL SULFUR CONCENTRATIONS

    EPA Science Inventory

    As the focus of environmental management has shifted toward regional- scale strategies, there is a growing need to develop statistical methodology for the estimation of regional trends in air pollution. This information is critical to assessing the effects of legislated emission ...

  15. Preliminary study on the variation of radon-222 inside greenhouse of Shouguang county, China.

    PubMed

    Li, Xiaohong; Xu, Xianqin; Li, Wanwei; Wang, Fei; Hai, Chunxu

    2016-03-01

    Studies on radon have become the focus of indoor radiation. In this study, we chose greenhouse to be the study field, the research aims to: (1) explore the diurnal variation of radon concentration inside greenhouse in Shouguang county, China; (2) pre-analyze the relationship between radon concentration, temperature and relative humidity, and shed light on the radon behavior characteristic inside greenhouse; (3) verify the feasibility of calculating radon radiation dose by using short-period detected radon concentrations in typical months in Shouguang county. The following conclusions were drawn. Firstly, the average radon levels in typical months in Shouguang county are all much higher than that in ordinary dwellings in China, diurnal and seasonal variations in radon levels are observed inside greenhouse. Secondly, temperature and relative humidity may play a role indirectly through affecting soil moisture and other factors. The mechanism need to be further studied. Thirdly, radon concentrations detected in typical months are still useful in preliminary estimation of radon radiation dose for vegetable-plant farmers in Shouguang county. PMID:26771243

  16. Preliminary study on the variation of radon-222 inside greenhouse of Shouguang county, China.

    PubMed

    Li, Xiaohong; Xu, Xianqin; Li, Wanwei; Wang, Fei; Hai, Chunxu

    2016-03-01

    Studies on radon have become the focus of indoor radiation. In this study, we chose greenhouse to be the study field, the research aims to: (1) explore the diurnal variation of radon concentration inside greenhouse in Shouguang county, China; (2) pre-analyze the relationship between radon concentration, temperature and relative humidity, and shed light on the radon behavior characteristic inside greenhouse; (3) verify the feasibility of calculating radon radiation dose by using short-period detected radon concentrations in typical months in Shouguang county. The following conclusions were drawn. Firstly, the average radon levels in typical months in Shouguang county are all much higher than that in ordinary dwellings in China, diurnal and seasonal variations in radon levels are observed inside greenhouse. Secondly, temperature and relative humidity may play a role indirectly through affecting soil moisture and other factors. The mechanism need to be further studied. Thirdly, radon concentrations detected in typical months are still useful in preliminary estimation of radon radiation dose for vegetable-plant farmers in Shouguang county.

  17. Radon-222 as a test of convective transport in a general circulation model

    NASA Technical Reports Server (NTRS)

    Jacob, Daniel J.; Prather, Michael J.

    1990-01-01

    A three-dimensional tracer model based on the Goddard Institude of Space Studies GCM is used to simulate the distribution of Rn-222 over North America to test the ability of the model to describe the transport of pollutants in the boundary layer and the exchange of mass between the boundary layer and the free troposphere. The model results are compared with surface observations from five sites in the U.S., showing that Rn-222 concentrations are primarily regulated by dry convection. The simulations show satisfactory agreement with observations although the model underpredicts observations at night and the simulated Rn-222 concentrations over the northeastern U.S. are too high in the spring and too low in the fall.

  18. Characterization of RADON-222 Entry Into a Basement Structure Surrounded by Low Permeability Soil

    NASA Astrophysics Data System (ADS)

    Ward, Dann Carlton

    1992-01-01

    An experimental facility has been developed to monitor the entry rate and concentration of ^ {222}Rn in two basement type structures surrounded by soil having a permeability on the order of 10^{-12} m^2 . A data acquisition system recorded environmental conditions outside and inside the structures, including basement air exchange rates, every 15 min. Indoor ^{222}Rn concentrations ranged from 400 to 1400 Bq m^{-3}. The observed ^{222}Rn entry rate is highly variable and has two primary components; a constant input rate caused by diffusion of ^ {222}Rn through the concrete walls and floor, and a variable rate that depends upon indoor-soil pressure differentials of only a few pascals. Pressure differentials are dependent upon wind speed and wind direction. Stack effect was not significant. During a two week period, with relatively calm winds, diffusion through the concrete walls and floor plus the floor-wall joint accounted for more than 80% of the total ^{222} Rn entry.

  19. Effective Dose Radon 222 of the Tap Water in Children and Adults People; Minab City, Iran

    PubMed Central

    Fakhri, Yadolah; Kargosha, Morteza; Langarizadeh, Ghazaleh; Zandsalimi, Yahya; Amirhajeloo, Leila Rasouli; Moradi, Mahboobeh; Moradi, Bigard; Mirzaei, Maryam

    2016-01-01

    222Rn is a radioactive, odorless, and colorless element which has a half-life of 3.83 days. One of 222Rn main resources are Groundwater (wells, springs, etc.). Hence, the use of groundwater with high concentration of 222Rn can increase the risk of lung and stomach cancers. Concentration of 222Rn in tap water of Minab city in two temperatures 5 and 15 ºC was measured by radon meter model RTM1668-2. The effective dose was calculated by equations proposed by UNSCEAR. Geometric mean concentration of 222Rn in drinking water was found to be 0.78±0.06 and 0.46±0.04 Bq/l at 5 and 15 °C (p value<0.05), respectively. The effective doses were 0.006 and 0.003 mSv/y for adults, and 0.011 and 0.007 mSv/y for the children, respectively (p value<0.05). Besides, the effective dose for adult through inhaling 222Rn at 5 and 15 °C were estimated 0.0021 and 0.0012mSv/y, respectively. Geometric mean concentration in 222Rn drinking water and effective dose received from drinking water and inhalation of 222Rn is lower than WHO and EPA standard limits. Increasing temperature of drinking water will decrease the effective dose received. Annual Effective dose received from inhalation and consumption of 222Rn in drinking water in children is more than adults. PMID:26573047

  20. Hydrogeologic controls on radon-222 in a buried valley-fractured bedrock aquifer system

    SciTech Connect

    Veeger, A.I.; Ruderman, N.C.

    1998-07-01

    A field study was conducted to evaluate the distribution of radon ({sup 222}Rn) and the hydrogeologic controls on its occurrence in the glacial and fractured rock aquifers of the Pawcatuck River Basin, Rhode Island. A total of 91 ground water samples were collected and analyzed for major chemical constituents as well as uranium and {sup 222}Rn. The three bedrock types underlying the study area include the Proterozoic Esmond and Sterling gneisses, and the Devonian Scituate Granite, each having average uranium contents of 1.9 ppm, 3.3 ppm, and 4.1 ppm, respectively. All wells sampled in this study yielded radon levels above the proposed US EPA limit of 300 pCi/L. Wells in areas underlain by the Esmond Suite had the lowest radon content (range 500 to 30,400 pCi/L, median 1400 pCi/L), areas underlain by the Sterling Suite were not significantly different but showed slightly higher concentrations, and the areas underlain by the Scituate Suite had significantly higher levels. High fluoride and alkalinity concentrations in ground water were found to be hydrogeochemical markers for elevated radon concentrations. These markers are believed to represent chemical reactions that produce remobilization of uranium in the host crystalline rock to more favorable siting along grain and fracture boundaries. Physical characteristics such as porosity and the location of uranium are controlling factors in the distribution of radon between surficial and bedrock wells, with bedrock aquifers exhibiting higher radon concentrations than surficial-materials aquifers in this basin.

  1. Soil radon ( 222 Rn) monitoring at Furnas Volcano (São Miguel, Azores): Applications and challenges

    NASA Astrophysics Data System (ADS)

    Silva, C.; Ferreira, T.; Viveiros, F.; Allard, P.

    2015-05-01

    A soil 222Rn continuous monitoring test was performed in three sampling points inside Furnas Volcano caldera and 222Rn concentration varied between 0 and 153000 Bq/m3. Multivariate regression and spectral analyses were applied to the time series registered in order to understand and filter the influence of external factors on soil 222Rn concentration and to recognise anomalies correlated with deep processes. The regression models show that barometric pressure, soil water content, soil temperature, soil CO2 flux, air temperature, relative air humidity and wind speed are the statistical meaningful variables explaining between 15.8% and 73.6% of 222Rn variations. Spectral analysis allowed to identify seasonal variations and daily variations associated with one cycle per day on winter months only in one of the monitored sites. This diurnal variation is correlated with air temperature, relative air humidity and wind speed cycles. The change in the location of the sampling points was caused by both artificial and natural constrains. On the three monitoring sites, after a period of continuous register, a sudden drop on the 222Rn concentration values was observed and the cause is still under debate. The work performed can be applied for seismovolcanic monitoring and for public health risk assessment.

  2. Static and push-pull methods using radon-222 to characterize dense nonaqueous phase liquid saturations.

    PubMed

    Davis, B M; Istok, J D; Semprini, L

    2003-01-01

    Naturally occurring radon in ground water can potentially be used as an in situ partitioning tracer to characterize dense nonaqueous phase liquid (DNAPL) saturations. The static method involves comparing radon concentrations in water samples from DNAPL-contaminated and noncontaminated portions of an aquifer, while the push-pull method involves the injection (push) and extraction (pull) of a radon-free test solution from a single well. In the presence of DNAPL, radon concentrations during the pull phase are retarded, with retardation manifested in greater dispersion of radon concentrations relative to a conservative tracer. The utility of these methods was investigated in the laboratory using a physical aquifer model (PAM). Static and push-pull tests were performed before and after contamination of the PAM sediment pack with trichloroethene (TCE), and after alcohol cosolvent flushing and pump-and-treat remediation. Numerical simulations were used to estimate the retardation factor for radon in push-pull tests. Radon partitioning was observed in static and push-pull tests conducted after TCE contamination. Calculated TCE saturations ranged up to 1.4% (static test) and 14.1% (push-pull test). Post-remediation tests showed decreases in TCE saturations. The results show that radon is sensitive to changes in DNAPL saturation in space and time. However, the methods are sensitive to DNAPL saturation heterogeneity, test location, sample size, and test design. The influence of these factors on test results, as well as the apparent overestimation of the retardation factor in push-pull tests, warrant further investigation.

  3. Development of Radon-222 as Natural Tracer for Monitoring the Remediation of NAPL in the Subsurface

    SciTech Connect

    Brian M. Davis; Lewis Semprini; Jonathan Istok

    2003-02-27

    Naturally occurring 222-radon in ground water can potentially be used as an in situ partitioning tracer to characterize dense nonaqueous phase liquid (DNAPL) saturations. The static method involves comparing radon concentrations in water samples from DNAPL-contaminated and non-contaminated portions of an aquifer. During a push-pull test, a known volume of test solution (radon-free water containing a conservation tracer) is first injected (''pushed'') into a well; flow is then reversed and the test solution/groundwater mixture is extracted (''pulled'') from the same well. In the presence of NAPL radon transport is retarded relative to the conservative tracer. Assuming linear equilibrium partitioning, retardation factors for radon can be used to estimate NAPL saturations.The utility of this methodology was evaluated in laboratory and field settings.

  4. Characteristics of attached radon-222 daughters under both laboratory and underground uranium-mine environments

    SciTech Connect

    Jackson, P.O.; Cooper, J.A.; Langford, J.C.; Petersen, M.R.

    1981-09-01

    The organic, inorganic, and radiological characteristics of airborne aerosols have been measured as a function of particle size in controlled atmosphere test chambers and operating uranium mines. Concentrations of benzo(a)pyrene in two mines ranged from 26 to 57 ng/m/sup 3/ of air. The carbon chain length of adsorbed n-alkanes was correlated with particle size. Normal mining activities produced an ore dust aerosol with mass median aerodynamic diameter (MMAD) greater than 2 ..mu..m. The elements Na, Al, Si, K, Ca, Ti, V, Fe, and U exhibited elemental ratios similar to bulk ore and had comparable MMAD's. The S, Zn, and Pb were higher in aerosols than bulk ore and were associated with smaller MMAD particulates. Radon daughter particle size distributions were influenced by the kinds of particulates generated in mining activity.

  5. Evaluation of groundwater discharge into small lakes based on the temporal distribution of radon-222

    USGS Publications Warehouse

    Dimova, N.T.; Burnett, W.C.

    2011-01-01

    In order to evaluate groundwater discharge into small lakes we constructed a model that is based on the budget of 222Rn (radon t1/2 5 3.8 d) as a tracer. The main assumptions in our model are that the lake's waters are wellmixed horizontally and vertically; the only significant 222Rn source is via groundwater discharge; and the only losses are due to decay and atmospheric evasion. In order to evaluate the groundwater-derived 222Rn flux, we monitored the 222Rn concentration in lake water over periods long enough (usually 1-3 d) to observe changes likely caused by variations in atmospheric exchange (primarily a function of wind speed and temperature). We then attempt to reproduce the observed record by accounting for decay and atmospheric losses and by estimating the total 222Rn input flux using an iterative approach. Our methodology was tested in two lakes in central Florida: one of which is thought to have significant groundwater inputs (Lake Haines) and another that is known not to have any groundwater inflows but requires daily groundwater augmentation from a deep aquifer (Round Lake). Model results were consistent with independent seepage meter data at both Lake Haines (positive seepage of ??? 1.6 ?? 104 m3 d-1 in Mar 2008) and at Round Lake (no net groundwater seepage). ?? 2011, by the American Society of Limnology and Oceanography, Inc.

  6. Physical Parameters Affecting the Emanation of RADON-222 from Coal Ash.

    NASA Astrophysics Data System (ADS)

    Barton, Terence Patrick

    The Rn-222 emanation coefficients for coal ash and parameters which affected them were measured. Samples of ash from both stoker fired and pulverized coal fired boilers were obtained. The stoker ash samples were mechanically separated into size fractions. The pulverized samples were too fine for mechanical sizing and were categorized qualitatively according to origin. Bulk density of the stoker fractions was measured and ranged from .488 to .944 g-cm('-3), increasing as a function of decreasing particle size. Bulk density of the pulverized ash ranged from 1.254 to 1.520 g-cm('-3). Specific gravity of the stoker fractions ranged from 2.017 to 2.390 g-cm('-3), also increasing as a function of decreasing particle size. Specific gravity of the pulverized ash ranged from 2.357 to 2.588 g-cm(' -3). Ra-226 content of the samples was determined by gamma spectrometric analysis of the 352-KeV gamma of Pb -214 and the 609-KeV gamma of Bi-214 from sealed samples of ash. Ra-226 concentrations in the stoker fractions ranged from 11.82 to 16.77 dpm-g('-1), increasing as a function of decreasing particle size. Ra-226 concentrations in the pulverized ash ranged from 6.44 to 7.59 dpm-g(' -1). Scintillation cells were constructed out of commonly available materials and a commercial preparation of ZnS(Ag) scintillator. Emanation chambers which allowed for moderately large sample masses were constructed. The procedure used to measure emanation coefficients was shown to be insensitive to ingrowth time at greater than 3 days ingrowth and relatively insensitive to variations in sample porosity. Emanation coefficients of the stoker fractions were measured at moisture contents of 0, 1.0, 10, 20, and 40 percent by weight. Within each size fraction the emanation coefficient increased as a function of moisture content, ranging from 9.58 x 10('-4) to 4.13 x 10('-2) between 0 and 20 percent moisture, respectively. Emanation coefficients also increased as a function of decreasing particle size

  7. Estimating the dynamics of groundwater input into the coastal zone via continuous radon-222 measurements.

    PubMed

    Burnett, William C; Dulaiova, Henrieta

    2003-01-01

    Submarine groundwater discharge (SGD) into the coastal zone has received increased attention in the last few years as it is now recognized that this process represents an important pathway for material transport. Assessing these material fluxes is difficult, as there is no simple means to gauge the water flux. To meet this challenge, we have explored the use of a continuous radon monitor to measure radon concentrations in coastal zone waters over time periods from hours to days. Changes in the radon inventories over time can be converted to fluxes after one makes allowances for tidal effects, losses to the atmosphere, and mixing with offshore waters. If one assumes that advective flow of radon-enriched groundwater (pore waters) represent the main input of 222Rn in the coastal zone, the calculated radon fluxes may be converted to water fluxes by dividing by the estimated or measured 222Rn pore water activity. We have also used short-lived radium isotopes (223Ra and 224Ra) to assess mixing between near-shore and offshore waters in the manner pioneered by. During an experiment in the coastal Gulf of Mexico, we showed that the mixing loss derived from the 223Ra gradient agreed very favorably to the estimated range based on the calculated radon fluxes. This allowed an independent constraint on the mixing loss of radon-an important parameter in the mass balance approach. Groundwater discharge was also estimated independently by the radium isotopic approach and was within a factor of two of that determined by the continuous radon measurements and an automated seepage meter deployed at the same site.

  8. The Origins and Pathways of RADON-222 Entering Into Basement Structures

    NASA Astrophysics Data System (ADS)

    Gadd, Milan Steven

    The entry rate of ^{222} Rn into a basement structure was measured continuously. These measurements demonstrated that radon entry did not vanish even when the structure was slightly pressurized. This persistent entry has been determined to be dominated by diffusion through the floor and walls and a combination of diffusion and convection through the floor-wall joint. The highest indoor radon concentrations occurred during calm periods when the pressure differentials between the inside and outside of the structure were small. The objectives of this work were to identify the origins of the radon and investigate the entry pathways. The radon could originate either in the concrete or in the soil surrounding the structure. Entry pathways into the basement were through the concrete floor and walls as well as through the floor-wall joint. The contributions of the origins and entry pathways were determined by continuously measuring the radon entry rate into the basement, using a trace gas system, and the flux density through portions of the floor and walls. Radon entry through the floor-wall joint could be controlled using a baseboard barrier system. Results indicated that, during calm conditions with wind speeds less than 1 m s^{ -1}, 25% of the radon enters through the floor -wall joint and 75% enters through the concrete. About 30% of the radon originated in the concrete floor and walls. A method for in-situ determination of the diffusion length and emanation fraction of radon in concrete was developed. For the concrete used in the structure, the average diffusion length and emanation fraction were 27 +/- 4 cm and 0.19 +/- 0.02 respectively.

  9. Radon-222, a proxy for vertical mixing of emissions in the urban nocturnal boundary layer

    NASA Astrophysics Data System (ADS)

    Chambers, S.; Williams, A. G.; Griffiths, A.; Crawford, J.; Zahorowski, W.

    2012-04-01

    There has been growing concern in recent decades regarding the health implications of fine particles (≤ 2.5μm), which are readily deposited deep within the lungs. In the interests of public health, and improving the predictive ability of Chemical Transport Models, it is imperative to improve our understanding of the diurnal variability of primary pollutant and precursor concentrations by, among others, improving our understanding of the underlying physics of transport and mixing processes. From the time of their release until they are removed from the atmosphere, the level of public exposure to emissions is closely related to rates of near-surface horizontal and vertical dispersion, the depth of the atmospheric boundary layer, and the venting from the boundary layer. These parameters, in turn, are dependent upon the amount and nature of mixing, which is closely related to atmospheric stability. With the exception of bushfires and dust storms, the greatest risk of public exposure to emissions occurs under "inversion" conditions, when the atmosphere is stably stratified. These very conditions are notoriously the most problematic for contemporary weather and chemical transport models. At such times the structure of the lowest 10-100m of the atmosphere can be quite complex, potentially containing multiple disconnected layers, and even stability measures based on surface similarity theory can fail (or yield inconclusive results) without sufficient vertical and temporal measurement resolution. Near-surface radon measurements provide a direct measure of the degree of dilution of surface-emitted scalar quantities by vertical mixing at night that is completely independent of local meteorological measurements and does not fail under conditions of near calm, which occur on the most stable nights. As such, they are a valuable proxy for potential pollution accumulation. In this study we analyse and discuss 22 months of continuous hourly observations within an urban airshed

  10. REGIONAL TRENDS IN RURAL SULFUR CONCENTRATIONS

    EPA Science Inventory

    This paper presents an analysis of trends in atmospheric concentrations of sulfur dioxide (SO,) and particulate sulfate (SO42-) at rural monitoring sites in the Clean Air Act Status and Trends Monitoring Network (CASTNet) from 1990 to 1999. A two-stage approach is used to estimat...

  11. Radon-222 content of natural gas samples from Upper and Middle Devonian sandstone and shale reservoirs in Pennsylvania—preliminary data

    USGS Publications Warehouse

    Rowan, E.L.; Kraemer, T.F.

    2012-01-01

    Samples of natural gas were collected as part of a study of formation water chemistry in oil and gas reservoirs in the Appalachian Basin. Nineteen samples (plus two duplicates) were collected from 11 wells producing gas from Upper Devonian sandstones and the Middle Devonian Marcellus Shale in Pennsylvania. The samples were collected from valves located between the wellhead and the gas-water separator. Analyses of the radon content of the gas indicated 222Rn (radon-222) activities ranging from 1 to 79 picocuries per liter (pCi/L) with an overall median of 37 pCi/L. The radon activities of the Upper Devonian sandstone samples overlap to a large degree with the activities of the Marcellus Shale samples.

  12. Analysis for measuring the interaction of groundwater and river water by using Radon-222: A case study in Yangsu-ri, Korea

    NASA Astrophysics Data System (ADS)

    Kim, J.; Lee, K. K.

    2014-12-01

    The water cycle is essential for the maintenance of ecosystems. Above all, water exchange between groundwater and river water has a significant impact on the water quality and hydrological zones. The natural radiogenic tracers such as Radon-222 can be used as good indicator for measuring the interaction between groundwater and river water even though the conventional methods of analysis are direct measurements of water flux, heat tracer methods, mass balance approaches and methods based on Darcy's law. The object of this study is to know the change of water environment and to do water resource management effectively by studying the interaction between groundwater and river water in Yangsu-ri of Korea. This paper used methods using temperature profiles, EC values, DO values and radon tracer. In this study, diurnal and seasonal variation of radon value was measured with other values. The result values proved that the more the region was influenced by river water, the closer to the values of river water the result values are. The radon value indicated a similar pattern with other values. The analysis also applied river water stage change by dam discharge. In addition, the mixing modeling of groundwater and river water was conducted to confirm the difference between the calculated value and the measured value. It turned out that radon tracer can be used as environmental tracer for analysis of the interaction between groundwater and river water.

  13. Source gases: Concentrations, emissions, and trends

    NASA Technical Reports Server (NTRS)

    Fraser, Paul J.; Harriss, Robert; Penkett, Stuart A.; Makide, Yoshihiro; Sanhueza, Eugenio; Alyea, Fred N.; Rowland, F. Sherwood; Blake, Don; Sasaki, Toru; Cunnold, Derek M.

    1991-01-01

    Source gases are defined as those gases that influence levels of stratospheric ozone (O3) by transporting species containing halogen, hydrogen, and nitrogen to the stratosphere. Examples are the CFC's, methane (CH4), and nitrous oxide (N2O). Other source gases that also come under consideration in an atmospheric O3 context are those that are involved in the O3 or hydroxyl (OH) radical chemistry of the troposphere. Examples are CH4, carbon monoxide (CO), and nonmethane hydrocarbons (NMHC's). Most of the source gases, along with carbon dioxide (CO2) and water vapor (H2O), are climatically significant and thus affect stratospheric O3 levels by their influence on stratospheric temperatures. Carbonyl sulphide (COS) could affect stratospheric O3 through maintenance of the stratospheric sulphate aerosol layer, which may be involved in heterogeneous chlorine-catalyzed O3 destruction. The previous reviews of trends and emissions of source gases, either from the context of their influence on atmospheric O3 or global climate change, are updated. The current global abundances and concentration trends of the trace gases are given in tabular format.

  14. Assessing the impact of atmospheric stability on locally and remotely sourced aerosols at Richmond, Australia, using Radon-222

    NASA Astrophysics Data System (ADS)

    Crawford, Jagoda; Chambers, Scott; Cohen, David; Williams, Alastair; Griffiths, Alan; Stelcer, Eduard

    2016-02-01

    A flexible radon-based scheme for the classification of nocturnal stability regimes was used for the interpretation of daily-integrated PM2.5 aerosol observations collected at Richmond, Australia, between 2007 and 2011. Source fingerprint concentrations for the dominant locally and remotely sourced aerosols were analysed by nocturnal radon stability category to characterise the influences of day-to-day changes in daily integrated atmospheric mixing. The fingerprints analysed included: smoke, vehicle exhaust, secondary sulfate and aged industrial sulfur. The largest and most consistent stability influences were observed on the locally sourced pollutants. Based on a 5-year composite, daily integrated concentrations of smoke were almost a factor of 7 higher when nocturnal conditions were classed as "stable" than when they were "near neutral". For vehicle emissions a factor of 4 was seen. However, when the winter months were considered in isolation, it was found that these factors increased to 11.5 (smoke) and 5.5 (vehicle emissions) for daily average concentrations. The changes in concentration of the remotely sourced pollutants with atmospheric stability were comparatively small and less consistent, probably as a result of the nocturnal inversion frequently isolating near-surface observations from non-local sources at night. A similar classification was performed using the commonly-adopted Pasquill-Gifford (PG) stability typing technique based on meteorological parameters. While concentrations of fingerprints associated with locally-sourced pollutants were also shown to be positively correlated with atmospheric stability using the PG classification, this technique was found to underestimate peak pollutant concentrations under stable atmospheric conditions by almost a factor of 2.

  15. Increasing the accuracy and temporal resolution of two-filter radon-222 measurements by correcting for the instrument response

    NASA Astrophysics Data System (ADS)

    Griffiths, Alan D.; Chambers, Scott D.; Williams, Alastair G.; Werczynski, Sylvester

    2016-06-01

    Dual-flow-loop two-filter radon detectors have a slow time response, which can affect the interpretation of their output when making continuous observations of near-surface atmospheric radon concentrations. While concentrations are routinely reported hourly, a calibrated model of detector performance shows that ˜ 40 % of the signal arrives more than an hour after a radon pulse is delivered. After investigating several possible ways to correct for the detector's slow time response, we show that a Bayesian approach using a Markov chain Monte Carlo sampler is an effective method. After deconvolution, the detector's output is redistributed into the appropriate counting interval and a 10 min temporal resolution can be achieved under test conditions when the radon concentration is controlled. In the case of existing archived observations, collected under less ideal conditions, the data can be retrospectively reprocessed at 30 min resolution. In one case study, we demonstrate that a deconvolved radon time series was consistent with the following: measurements from a fast-response carbon dioxide monitor; grab samples from an aircraft; and a simple mixing height model. In another case study, during a period of stable nights and days with well-developed convective boundary layers, a bias of 18 % in the mean daily minimum radon concentration was eliminated by correcting for the instrument response.

  16. Seasonal variation of indoor radon-222 levels in dwellings in Ramallah province and East Jerusalem suburbs, Palestine.

    PubMed

    Leghrouz, Amin A; Abu-Samreh, Mohammad M; Shehadeh, Ayah K

    2012-01-01

    This study presents the seasonal variations of indoor radon levels in dwellings located in the Ramallah province and East Jerusalem suburbs, Palestine. The measurements were performed during the summer and winter of the year 2006/2007 using CR-39 solid-state-nuclear-track detectors. The total number of investigated buildings is 75 in summer and 81 in winter. A total number of 142 dosemeters are installed in dwellings for each season for a period of almost 100 d. The radon concentration levels in summer varied from 43 to 192 Bq m(-3) for buildings in the Ramallah province and from 30 to 655 Bq m(-3) for East Jerusalem suburbs. In winter, the radon concentration levels are found to vary from 38 to 375 Bq m(-3) in the Ramallah buildings and from 35 to 984 Bq m(-3) in East Jerusalem suburbs. The obtained results for radon concentration levels in most places are found to be within the accepted international levels.

  17. Radon 222 tracing of soil and forest canopy trace gas exchange in an open canopy boreal forest

    NASA Technical Reports Server (NTRS)

    Ussler, William, III; Chanton, Jeffrey P.; Kelley, Cheryl A.; Martens, Christopher S.

    1994-01-01

    A set of continuous, high-resolution atmospheric radon (Rn-222) concentration time series and radon soil flux measurements were acquired during the summer of 1990 at a micrometeorological tower site 13 km northwest of Schefferville, Quebec, Canada. The tower was located in a dry upland, open-canopy lichen-spruce woodland. For the period July 23 to August 1, 1990, the mean radon soil flux was 41.1 +/- 4.8 Bq m(exp -2)/h. Radon surface flux from the two end-member forest floor cover types (lichen mat and bare soil) were 38.8 +/- 5.1 and 61.8 +/- 15.6 Bq m(exp -2)/h, respectively. Average total forest canopy resistances computed using a simple 'flux box' model for radon exchange between the forest canopy and the overlying atmosphere range from 0.47 +/- 0.24 s cm(exp -1) to 2.65 +/- 1.61 cm(exp -1) for daytime hours (0900-1700 LT) and from 3.44 +/- 0.91 s cm(exp -1) to 10.55 +/- 7.16 s cm(exp -1) for nighttime hours (2000-0600) for the period July 23 to August 6, 1990. Continuous radon profiling of canopy atmospheres is a suitable approach for determining rates of biosphere/atmosphere trace gas exchange for remote field sites where daily equipment maintenance is not possible. where daily equipment maintenance is not possible.

  18. Indoor air-assessment: Indoor concentrations of environmental carcinogens

    SciTech Connect

    Gold, K.W.; Naugle, D.F.; Berry, M.A.

    1991-01-01

    In the report, indoor concentration data are presented for the following general categories of air pollutants: radon-222, environmental tobacco smoke (ETS), asbestos, gas phase organic compounds, formaldehyde, polycyclic aromatic hydrocarbons (PAH), pesticides, and inorganic compounds. These pollutants are either known or suspect carcinogens (i.e., radon-222, asbestos) or more complex mixtures or classes of compounds which contain known or suspect carcinogens. Concentration data for individual carcinogenic compounds in complex mixtures are usually far from complete. The data presented for complex mixtures often include compounds which are not carcinogenic or for which data are insufficient to evaluate carcinogenicity. Their inclusion is justified, however, by the possibility that further work may show them to be carcinogens, cocarcinogens, initiators or promotors, or that they may be employed as markers (e.g., nicotine, acrolein) for the estimation of exposure to complex mixtures.

  19. Modeling variability and trends in pesticide concentrations in streams

    USGS Publications Warehouse

    Vecchia, A.V.; Martin, J.D.; Gilliom, R.J.

    2008-01-01

    A parametric regression model was developed for assessing the variability and long-term trends in pesticide concentrations in streams. The dependent variable is the logarithm of pesticide concentration and the explanatory variables are a seasonal wave, which represents the seasonal variability of concentration in response to seasonal application rates; a streamflow anomaly, which is the deviation of concurrent daily streamflow from average conditions for the previous 30 days; and a trend, which represents long-term (inter-annual) changes in concentration. Application of the model to selected herbicides and insecticides in four diverse streams indicated the model is robust with respect to pesticide type, stream location, and the degree of censoring (proportion of nondetections). An automatic model fitting and selection procedure for the seasonal wave and trend components was found to perform well for the datasets analyzed. Artificial censoring scenarios were used in a Monte Carlo simulation analysis to show that the fitted trends were unbiased and the approximate p-values were accurate for as few as 10 uncensored concentrations during a three-year period, assuming a sampling frequency of 15 samples per year. Trend estimates for the full model were compared with a model without the streamflow anomaly and a model in which the seasonality was modeled using standard trigonometric functions, rather than seasonal application rates. Exclusion of the streamflow anomaly resulted in substantial increases in the mean-squared error and decreases in power for detecting trends. Incorrectly modeling the seasonal structure of the concentration data resulted in substantial estimation bias and moderate increases in mean-squared error and decreases in power. ?? 2008 American Water Resources Association.

  20. Quartz concentration trends in metal and nonmetal mining.

    PubMed

    Watts, Winthrop F; Huynh, Tran B; Ramachandran, Gurumurthy

    2012-01-01

    From 1974 through 2010, the Mine Safety and Health Administration (MSHA) collected nearly 147,000 respirable dust samples with a mass of at least 0.1 mg and a minimum of 1% quartz. These samples represent about 50% of all respirable dust compliance samples collected by MSHA. Analysis of these data shows that pockets of high concentrations and overexposure continue to exist. At underground mines, from 2005 to 2010, occupations with >20% of the samples exceeding the permissible exposure limit (PEL) and geometric mean quartz concentrations exceeding the ACGIH threshold limit value of 25 μg/m(3) included mucking, crusher operator, general laborer/utility, and front-end loader operator. During the same period, stone and rock saw operators and bagger and packers working at surface mines and mills also had >20% of the samples exceeding the PEL and geometric mean quartz concentrations >25 μg/m(3). Regardless of mine type or location, slow but steady improvement in exposure levels is seen in jobs involving crushing operations, which are widespread in the mining industry. Crusher operators are more likely to work in an enclosed area where it is easier to apply dust controls and air conditioning. A downward trend is also observed for vehicle equipment operators who drive load-haul-dumps, front-end loaders, trucks, and similar equipment. Crusher operators and vehicle equipment operators represent occupational categories that are widely sampled by MSHA inspectors. A small but statistically significant reduction in the overall mean respirable quartz dust and quartz concentrations from 1993 to 2010 was observed in most commodity groups. Variability from year to year and between commodities is high. Reduction in respirable quartz dust concentration does not necessarily correspond to a reduction in quartz concentration within the same commodity group. These trends are consistent with those reported in previous studies.

  1. Recent trends in nutrient concentrations in Swedish agricultural rivers.

    PubMed

    Ulén, B; Fölster, J

    2007-02-15

    In five out of twelve Swedish agricultural rivers examined during the period 1993-2004, significant trends for decreasing concentrations of reactive inorganic nitrogen (RIN) were indicated after flow normalisation. These decreases were constant (equal to 2-4% per year), most apparent in the Scania region, and weakly correlated to reductions in livestock density (Pearson correlation coefficient -0.825). The number of grazing cattle livestock units per unit area of arable land decreased on average by 14% and that of non-grazing cattle by 17% during 1985-2003. Based on estimates of root-zone leaching, increased area of set-aside and recent EU subsidisation of catch crops (with/without spring tillage) were suggested to be additional substantial causes but these changes were only rapid very recently (years 2000-2001). A significant and constant decrease in reactive phosphorus (RP) (3% per year) was observed in one river, mainly during the season of low flow, with reduced load from point sources suggested to be the main reason. Significant and constant reductions equal to 3-8% per year in concentrations of non-reactive phosphorus (NRP) were calculated for five rivers. These improvements were weakly correlated to the length of grassed buffer zones along the watercourses in arable parts of the river basin (Pearson correlation coefficient -0.845). Establishment of such zones also took place more recently, and together with constructed wetlands represent on average 0.5% of the agricultural area.

  2. Radon-222 and its parent radionuclides in groundwater from two study areas in New Jersey and Maryland, U.S.A.

    USGS Publications Warehouse

    Wanty, R.B.; Johnson, S.L.; Briggs, P.H.

    1991-01-01

    A study of groundwater chemistry and radionuclide mobility in New Jersey and Maryland was conducted to investigate natural processes that control the mobility of radionuclides in the water-rock system. Groundwater was sampled from two geological units in New Jersey and from six in Maryland. The water sampled was from aquifiers in fractured metamorphic rocks of varying composition and metamorphic grade. In both areas, groundwater chemistry was affected most by aquifier mineralogy and lithology; concentrations of total dissolved U, 226Ra and 222Rn were similarly affected. In evey sample for which measurements were made, dissolved Utotal and 226Ra were present in much lower concentrations than 222Rn when expressed in terms of their radioactivity. On the other hand, the total amount of 222Rn that could be produced in these rocks, given their U contents, is much higher than the concentrations observed in groundwater. Thus, the emanating efficiencies of the aquifer rocks studied must be near 10% or less. Such low emanating efficiencies require that a fraction of the 226Ra in the rock be located close to the water-rock interface so that 222Rn, when produced, can be rapidly and efficiently transferred to the aqueous phase. This condition is established when a similar fraction of the U is in a readily leachable position. No known U or Ra solids were supersaturated in any of the samples. Thus, adsorption processes probably play a role in limiting mobilities of Utotal and 226Ra. Concentrations of Utotal and 226Ra found in the water samples are comparable to those found in experimental studies of adsorption onto mineral surfaces. ?? 1991.

  3. [Radon 222Rn in residential buildings of Swieradów Zdrój and Czerniawa Zdrój].

    PubMed

    Pachocki, K A; Gorzkowski, B; Rózycki, Z; Wilejczyk, E; Smoter, J

    2000-01-01

    Swieradrów Zdrój and Czerniawa Zdrój are located in Region Izera Block. A total of 789 radon passive dosimeters were distributed in 183 dwellings in these town Swieradów Zdrój and Czerniawa Zdrój to measure the indoor radon concentration in 1999. Three-five measurements were performed in each dwelling, one in the basement, and the others in the main bedroom, in the kitchen, in the bathroom, since these rooms are the most frequently occupied. In addition, the occupants of each dwelling were requested to answer a questionnaire in which a number of questions about the building, ventilation habits and other related aspects were formulated. A charcoal detectors (Pico-Rad system) were used in experiment. It is a passive short-term screening method of radon gas concentration measurements. The indoor radon level was found to range from 14.8 Bq/m3 to 5,723.9 Bq/m3. The arithmetic mean overall indoor concentration was 420.4 Bq/m3 and the geometric mean was 159.7 Bq/m3. The average concentration of indoor radon, which reflects the real risk for inhabitants, is 193.5 Bq/m3. The results hand a log-normal distribution. In Poland, an action level of 400 Bq/m3 was recommended for existing buildings and 200 Bq/m3 for newly built (after 1.01.1998) buildings. In about 23% rooms the level of Rn-222 were above the top limit of 400 Bq/m3. The highest average concentrations were present in a basement (mean 919.9 Bq/m3). A decrease of average activity were observed at the upper levels: at the ground floor (225.2 Bq/m3), at the first floor and at the higher floors (137.6 Bq/m3). The above results indicate that radon emission from the ground provides the main contribution to the radon concentration measured in dwellings indoors in Swieradów Zdrój and Czerniawa Zdrój. The effective dose to the population of the Swieradów Zdrój and Czerniawa Zdrój from indoor radon and its progeny can be derived from this data if we use an equilibrium factor of 0.4 between radon and its progeny

  4. Trends in pesticide concentrations and use for major rivers of the United States.

    PubMed

    Ryberg, Karen R; Gilliom, Robert J

    2015-12-15

    Trends in pesticide concentrations in 38 major rivers of the United States were evaluated in relation to use trends for 11 commonly occurring pesticide compounds. Pesticides monitored in water were analyzed for trends in concentration in three overlapping periods, 1992-2001, 1997-2006, and 2001-2010 to facilitate comparisons among sites with variable sample distributions over time and among pesticides with changes in use during different periods and durations. Concentration trends were analyzed using the SEAWAVE-Q model, which incorporates intra-annual variability in concentration and measures of long-term, mid-term, and short-term streamflow variability. Trends in agricultural use within each of the river basins were determined using interval-censored regression with high and low estimates of use. Pesticides strongly dominated by agricultural use (cyanazine, alachlor, atrazine and its degradate deethylatrazine, metolachlor, and carbofuran) had widespread agreement between concentration trends and use trends. Pesticides with substantial use in both agricultural and nonagricultural applications (simazine, chlorpyrifos, malathion, diazinon, and carbaryl) had concentration trends that were mostly explained by a combination of agricultural-use trends, regulatory changes, and urban use changes inferred from concentration trends in urban streams. When there were differences, concentration trends usually were greater than use trends (increased more or decreased less). These differences may occur because of such factors as unaccounted pesticide uses, delayed transport to the river through groundwater, greater uncertainty in the use data, or unquantified land use and management practice changes.

  5. Trends in pesticide concentrations and use for major rivers of the United States.

    PubMed

    Ryberg, Karen R; Gilliom, Robert J

    2015-12-15

    Trends in pesticide concentrations in 38 major rivers of the United States were evaluated in relation to use trends for 11 commonly occurring pesticide compounds. Pesticides monitored in water were analyzed for trends in concentration in three overlapping periods, 1992-2001, 1997-2006, and 2001-2010 to facilitate comparisons among sites with variable sample distributions over time and among pesticides with changes in use during different periods and durations. Concentration trends were analyzed using the SEAWAVE-Q model, which incorporates intra-annual variability in concentration and measures of long-term, mid-term, and short-term streamflow variability. Trends in agricultural use within each of the river basins were determined using interval-censored regression with high and low estimates of use. Pesticides strongly dominated by agricultural use (cyanazine, alachlor, atrazine and its degradate deethylatrazine, metolachlor, and carbofuran) had widespread agreement between concentration trends and use trends. Pesticides with substantial use in both agricultural and nonagricultural applications (simazine, chlorpyrifos, malathion, diazinon, and carbaryl) had concentration trends that were mostly explained by a combination of agricultural-use trends, regulatory changes, and urban use changes inferred from concentration trends in urban streams. When there were differences, concentration trends usually were greater than use trends (increased more or decreased less). These differences may occur because of such factors as unaccounted pesticide uses, delayed transport to the river through groundwater, greater uncertainty in the use data, or unquantified land use and management practice changes. PMID:26318227

  6. Radon-222 in the lunar atmosphere.

    NASA Technical Reports Server (NTRS)

    Brodzinski, R. L.

    1972-01-01

    In 1969 Yeh and Van Allen set upper limits for the alpha-particle emissivity of the moon. The equilibrium surface activity reported by Turkevich et al. (1970) for each alpha active Rn-222 daughter at Mare Tranquillitatis cannot be reconciled with existing diffusion theory. The data, therefore, suggest that earth based diffusion constants are not applicable in the vacuum conditions of the moon, or that there are substantial variations in the uranium content of the moon over relatively small distances.

  7. Trends in pesticide concentrations and use for major rivers of the United States

    USGS Publications Warehouse

    Ryberg, Karen R.; Gilliom, Robert J.

    2015-01-01

    Pesticides strongly dominated by agricultural use (cyanazine, alachlor, atrazine and its degradate deethylatrazine, metolachlor, and carbofuran) had widespread agreement between concentration trends and use trends. Pesticides with substantial use in both agricultural and nonagricultural applications (simazine, chlorpyrifos, malathion, diazinon, and carbaryl) had concentration trends that were mostly explained by a combination of agricultural-use trends, regulatory changes, and urban use changes inferred from concentration trends in urban streams. When there were differences, concentration trends usually were greater than use trends (increased more or decreased less). These differences may occur because of such factors as unaccounted pesticide uses, delayed transport to the river through groundwater, greater uncertainty in the use data, or unquantified land use and management practice changes.

  8. Trends in mercury wet deposition and mercury air concentrations across the U.S. and Canada.

    PubMed

    Weiss-Penzias, Peter S; Gay, David A; Brigham, Mark E; Parsons, Matthew T; Gustin, Mae S; Ter Schure, Arnout

    2016-10-15

    This study examined the spatial and temporal trends of mercury (Hg) in wet deposition and air concentrations in the United States (U.S.) and Canada between 1997 and 2013. Data were obtained from the National Atmospheric Deposition Program (NADP) and Environment Canada monitoring networks, and other sources. Of the 19 sites with data records from 1997-2013, 53% had significant negative trends in Hg concentration in wet deposition, while no sites had significant positive trends, which is in general agreement with earlier studies that considered NADP data up until about 2010. However, for the time period 2007-2013 (71 sites), 17% and 13% of the sites had significant positive and negative trends, respectively, and for the time period 2008-2013 (81 sites) 30% and 6% of the sites had significant positive and negative trends, respectively. Non-significant positive tendencies were also widespread. Regional trend analyses revealed significant positive trends in Hg concentration in the Rocky Mountains, Plains, and Upper Midwest regions for the recent time periods in addition to significant positive trends in Hg deposition for the continent as a whole. Sulfate concentration trends in wet deposition were negative in all regions, suggesting a lower importance of local Hg sources. The trend in gaseous elemental Hg from short-term datasets merged as one continuous record was broadly consistent with trends in Hg concentration in wet deposition, with the early time period (1998-2007) producing a significantly negative trend (-1.5±0.2%year(-1)) and the recent time period (2008-2013) displaying a flat slope (-0.3±0.1%year(-1), not significant). The observed shift to more positive or less negative trends in Hg wet deposition primarily seen in the Central-Western regions is consistent with the effects of rising Hg emissions from regions outside the U.S. and Canada and the influence of long-range transport in the free troposphere. PMID:26803218

  9. Trends in concentrations and use of agricultural herbicides for Corn Belt rivers, 1996-2006

    USGS Publications Warehouse

    Vecchia, A.V.; Gilliom, R.J.; Sullivan, D.J.; Lorenz, D.L.; Martin, J.D.

    2009-01-01

    Trends in the concentrations and agricultural use of four herbicides (atrazine, acetochlor, metolachlor, and alachlor) were evaluated for major rivers of the Corn Belt for two partially overlapping time periods: 1996-2002 and 2000-2006. Trends were analyzed for 11 sites on the mainstems and selected tributaries in the Ohio, Upper Mississippi, and Missouri River Basins. Concentration trends were determined using a parametric regression model designed for analyzing seasonal variability, flow-related variability, and trends in pesticide concentrations(SEAWAVE-Q).TheSEAWAVE-Qmodel accounts for the effect of changing flow conditions in order to separate changes caused by hydrologic conditions from changes caused by other factors, such as pesticide use. Most of the trends in atrazine and acetochlor concentrations for both time periods were relatively small and nonsignificant, but metolachlor and alachlor were dominated by varying magnitudes of concentration downtrends. Overall, with trends expressed as a percent change per year, trends in herbicide concentrations were consistent with trends in agricultural use; 84 of 88 comparisons for different sites, herbicides, and time periods showed no significant difference between concentration trends and agricultural use trends. Results indicate that decreasing use appears to have been the primary cause for the concentration downtrends during 1996-2006 and that, while there is some evidence that nonuse management factors may have reduced concentrations in some rivers, reliably evaluating the influence of these factors on pesticides in large streams and rivers will require improved, basin-specific information on both management practices and use over time. ?? 2009 American Chemical Society.

  10. Trends in Pesticide Concentrations in Corn-Belt Streams, 1996-2006

    USGS Publications Warehouse

    Sullivan, Daniel J.; Vecchia, Aldo V.; Lorenz, David L.; Gilliom, Robert J.; Martin, Jeffrey D.

    2009-01-01

    Trends in the concentrations of commonly occurring pesticides in the Corn Belt of the United States were assessed, and the performance and application of several statistical methods for trend analysis were evaluated. Trends in the concentrations of 11 pesticides with sufficient data for trend assessment were assessed at up to 31 stream sites for two time periods: 1996-2002 and 2000-2006. Pesticides included in the trend analyses were atrazine, acetochlor, metolachlor, alachlor, cyanazine, EPTC, simazine, metribuzin, prometon, chlorpyrifos, and diazinon. The statistical methods applied and compared were (1) a modified version of the nonparametric seasonal Kendall test (SEAKEN), (2) a modified version of the Regional Kendall test, (3) a parametric regression model with seasonal wave (SEAWAVE), and (4) a version of SEAWAVE with adjustment for streamflow (SEAWAVE-Q). The SEAKEN test is a statistical hypothesis test for detecting monotonic trends in seasonal time-series data such as pesticide concentrations at a particular site. Trends across a region, represented by multiple sites, were evaluated using the regional seasonal Kendall test, which computes a test for an overall trend within a region by computing a score for each season at each site and adding the scores to compute the total for the region. The SEAWAVE model is a parametric regression model specifically designed for analyzing seasonal variability and trends in pesticide concentrations. The SEAWAVE-Q model accounts for the effect of changing flow conditions in order to separate changes caused by hydrologic trends from changes caused by other factors, such as pesticide use. There was broad, general agreement between unadjusted trends (no adjustment for streamflow effects) identified by the SEAKEN and SEAWAVE methods, including the regional seasonal Kendall test. Only about 10 percent of the paired comparisons between SEAKEN and SEAWAVE indicated a difference in the direction of trend, and none of these had

  11. Daily variation of radon gas and its short-lived progeny concentration near ground level and estimation of aerosol residence time

    NASA Astrophysics Data System (ADS)

    M, Mohery; A, M. Abdallah; A, Ali; S, S. Baz

    2016-05-01

    Atmospheric concentrations of radon (222Rn) gas and its short-lived progenies 218Po, 214Pb, and 214Po were continuously monitored every four hours at the ground level in Jeddah city, Kingdom of Saudi Arabia. The measurements were performed three times every week, starting from November 2014 to October 2015. A method of electrostatic precipitation of positively charged 218Po and 214Po by a positive voltage was applied for determining 222Rn gas concentration. The short-lived 222Rn progeny concentration was determined by using a filter holder connected with the alpha-spectrometric technique. The meteorological parameters (relative air humidity, air temperature, and wind speed) were determined during the measurements of 222Rn and its progeny concentrations. 222Rn gas as well as its short-lived progeny concentration display a daily and seasonal variation with high values in the night and early morning hours as compared to low values at noon and in the afternoon. The observed monthly atmospheric concentrations showed a seasonal trend with the highest values in the autumn/winter season and the lowest values in the spring/summer season. Moreover, and in parallel with alpha-spectrometric measurements, a single filter-holder was used to collect air samples. The deposited activities of 214Pb and the long-lived 222Rn daughter 210Pb on the filter were measured with the gamma spectrometric technique. The measured activity concentrations of 214Pb by both techniques were found to be relatively equal largely. The highest mean seasonally activity concentrations of 210Pb were observed in the autumn/winter season while the lowest mean were observed in the spring/summer season. The mean residence time (MRT) of aerosol particles in the atmospheric air could be estimated from the activity ratios of 210Pb/214Pb. Project supported by the Deanship of Scientific Research (DSR), King Abdulaziz University, Jeddah (Grant No. 291/965/1434).

  12. Surface ozone concentrations and ecosystem health: past trends and a guide to future projections.

    PubMed

    Cape, J N

    2008-08-01

    This paper reviews current understanding of the sources and sinks of ozone in the troposphere, recent studies of long-term trends, and the factors which have to be taken into consideration when constructing and interpreting future models of ozone concentration. The factors controlling surface O(3) concentrations are discussed initially to provide a basis for the ensuing discussion, followed by a summary of the evidence for recent trends in ground-level ozone concentrations, i.e. over the past 3 decades, which have shown a significant increase in the annual average in 'background' air typical of the unpolluted northern hemisphere. Closer to precursor sources, although urban winter concentrations have increased, rural peak spring and summer concentrations during ozone 'episodes' have decreased markedly in response to emissions reductions. In order to determine whether such trends are meaningful, the statistical techniques for determining temporal trends are reviewed. The possible causes of long-term trends in ozone are then discussed, with particular reference to the use of chemistry-transport models to interpret past trends. Such models are also used to make predictions of future trends in surface ozone concentrations, but few are comprehensive in integrating future climate changes with changes in land use and in emissions of ozone precursors. Guidance is given on the likely effects of climate/precursor/chemistry interactions so that model predictions can be judged.

  13. An overview of time trends in organic contaminant concentrations in marine mammals: going up or down?

    PubMed

    Law, Robin J

    2014-05-15

    In this article I review recent trends reported in the literature from 2008 to date for organic contaminant concentrations in marine mammal tissues worldwide, in order to get an idea of where we stand currently in relation to the control of hazardous substances. For many contaminants which have been subject to regulation regarding their production and use (e.g. organochlorine pesticides, PBDE and HBCD flame retardants, butyltins) trends are downwards. For perfluorinated compounds, trends are more mixed. For dioxins, furans and dioxin-like CBs, there are no recent data, for either concentrations or trends. For CBs overall, earlier downward trends in concentration in UK harbour porpoises following regulation beginning in the 1980s have stalled, and remain at toxicologically significant levels. This raises concerns for killer whales and bottlenose dolphins who, because of their larger size and greater bioaccumulation potential, have higher levels still, often far above accepted toxicological threshold values. PMID:24703807

  14. An overview of time trends in organic contaminant concentrations in marine mammals: going up or down?

    PubMed

    Law, Robin J

    2014-05-15

    In this article I review recent trends reported in the literature from 2008 to date for organic contaminant concentrations in marine mammal tissues worldwide, in order to get an idea of where we stand currently in relation to the control of hazardous substances. For many contaminants which have been subject to regulation regarding their production and use (e.g. organochlorine pesticides, PBDE and HBCD flame retardants, butyltins) trends are downwards. For perfluorinated compounds, trends are more mixed. For dioxins, furans and dioxin-like CBs, there are no recent data, for either concentrations or trends. For CBs overall, earlier downward trends in concentration in UK harbour porpoises following regulation beginning in the 1980s have stalled, and remain at toxicologically significant levels. This raises concerns for killer whales and bottlenose dolphins who, because of their larger size and greater bioaccumulation potential, have higher levels still, often far above accepted toxicological threshold values.

  15. Trends in serum relaxin concentration among elite collegiate female athletes

    PubMed Central

    Dragoo, Jason L; Castillo, Tiffany N; Korotkova, Tatiana A; Kennedy, Ashleigh C; Kim, Hyeon Joo; Stewart, Dennis R

    2011-01-01

    Purpose: This study was designed to investigate the relationship between serum relaxin concentration (SRC) and menstrual history and hormonal contraceptive use among elite collegiate female athletes. Evaluation of SRC in athletes is necessary, because relaxin has been associated with increased knee joint laxity and decreased anterior cruciate ligament (ACL) strength in animal models. Methods: National Collegiate Athletic Association Division I female athletes participating in sports at high risk for ACL tears – basketball, field hockey, gymnastics, lacrosse, soccer, and volleyball – were invited to participate. All participants completed a questionnaire about their menstrual history and hormonal contraceptive use. Venipuncture was performed to obtain samples of serum progesterone and relaxin. Samples were obtained during the mid-luteal phase from ovulating participants, and between the actual or projected cycle days 21 to 24, from anovulatory participants. Serum concentration of relaxin and progesterone was determined by ELISA and the data were analyzed using SPSS statistical software with significance set at P = 0.05. Results: 169 female athletes participated. The mean SRC among all participants was 3.08 ± 6.66 pg/mL). The mean SRC differed significantly between those participants using hormonal contraceptives (1.41 pg/mL) and those not using hormonal contraceptives (3.08 pg/mL, P = 0.002). Mean SRC was lowest among amenorrheic participants (1.02 pg/mL) and highest among oligomenorrheic participants (3.71 pg/mL) and eumenorrheic participants (3.06 pg/mL); these differences were not significant (P = 0.53). Mean serum progesterone concentration (SPC) differed significantly between those participants using hormonal contraceptives (2.80 ng/mL), and those not using hormonal contraceptives (6.99 ng/mL, P < 0.0001). Conclusions: There is a positive correlation between serum progesterone and SRC and an attenuation of SRC with hormonal contraceptive use. Our results

  16. Trend and climate signals in seasonal air concentration of organochlorine pesticides over the Great Lakes

    NASA Astrophysics Data System (ADS)

    Gao, Hong; Ma, Jianmin; Cao, Zuohao; Dove, Alice; Zhang, Lisheng

    2010-08-01

    Following worldwide bans or restrictions, the atmospheric level of many organochlorine pesticides (OCPs) over the Great Lakes exhibited a decreasing trend since the 1980s in various environmental compartments. Atmospheric conditions also influence variation and trend of OCPs. In the present study a nonparametric Mann-Kendall test with an additional process to remove the effect of temporal (serial) correlation was used to detect the temporal trend of OCPs in the atmosphere over the Great Lakes region and to examine the statistical significance of the trends. Using extended time series of measured air concentrations over the Great Lakes region from the Integrated Atmospheric Deposition Network, this study also revisits relationships between seasonal mean air concentration of OCPs and major climate variabilities in the Northern Hemisphere. To effectively extract climate signals from the temporal trend of air concentrations, we detrended air concentrations through removing their linear trend, which is driven largely by their respective half-lives in the atmosphere. The interannual variations of the extended time series show a good association with interannual climate variability, notably, the North Atlantic Oscillation (NAO) and the El Niño-Southern Oscillation. This study demonstrates that the stronger climate signals can be extracted from the detrended time series of air concentrations of some legacy OCPs. The detrended concentration time series also help to interpret, in addition to the connection with interannual variation of the NAO, the links between atmospheric concentrations of OCPs and decadal or interdecadal climate change.

  17. Trends in pesticide concentrations in urban streams in the United States, 1992-2008

    USGS Publications Warehouse

    Ryberg, Karen R.; Vecchia, Aldo V.; Martin, Jeffrey D.; Gilliom, Robert J.

    2010-01-01

    Pesticide concentration trends in streams dominated by urban land use were assessed using data from 27 urban streams sampled as part of the U.S. Geological Survey National Water-Quality Assessment Program. The sites were divided into four regions, Northeast, South, Midwest, and West, to examine possible regional patterns. Three partially overlapping 9-year periods (1992-2000, 1996-2004, and 2000-2008) were examined for eight herbicides and one degradation product (simazine, prometon, atrazine, deethylatrazine, metolachlor, trifluralin, pendimethalin, tebuthiuron, and Dacthal), and five insecticides and two degradation products (chlorpyrifos, malathion, diazinon, fipronil, fipronil sulfide, desulfinylfipronil, and carbaryl). The data were analyzed for trends in concentration using a parametric regression model with seasonality, flow-related variability, and trend, called SEAWAVE-Q. The SEAWAVE-Q model also was used to generate estimated daily concentration percentiles for each analysis period to provide a summary of concentration magnitudes. For herbicides, the largest 90th percentiles of estimated concentrations for simazine were in the South, prometon at some sites in all of the regions, atrazine and deethylatrazine in the South and Midwest, metolachlor in the Midwest and a few sites in the South, pendimethalin at scattered sites in all of the regions, and tebuthiuron in the South and a few sites in the Midwest and West. For insecticides, the largest 90th percentiles of estimated concentrations for diazinon and carbaryl were distributed among various sites in all regions (especially during 1996-2004), and fipronil at isolated sites in all of the regions during 2000-2008. Trend analysis results for the herbicides indicated many significant trends, both upward and downward, with varying patterns depending on period, region, and herbicide. Overall, deethylatrazine showed the most consistent pattern of upward trends, especially in the Northeast (2000-2008), South

  18. Groundwater level and nitrate concentration trends on Mountain Home Air Force Base, southwestern Idaho

    USGS Publications Warehouse

    Williams, Marshall L.

    2014-01-01

    Mountain Home Air Force Base in southwestern Idaho draws most of its drinking water from the regional aquifer. The base is located within the State of Idaho's Mountain Home Groundwater Management Area and is adjacent to the State's Cinder Cone Butte Critical Groundwater Area. Both areas were established by the Idaho Department of Water Resources in the early 1980s because of declining water levels in the regional aquifer. The base also is listed by the Idaho Department of Environmental Quality as a nitrate priority area. The U.S. Geological Survey, in cooperation with the U.S. Air Force, began monitoring wells on the base in 1985, and currently monitors 25 wells for water levels and 17 wells for water quality, primarily nutrients. This report provides a summary of water-level and nitrate concentration data collected primarily between 2001 and 2013 and examines trends in those data. A Regional Kendall Test was run to combine results from all wells to determine an overall regional trend in water level. Groundwater levels declined at an average rate of about 1.08 feet per year. Nitrate concentration trends show that 3 wells (18 percent) are increasing in nitrate concentration trend, 3 wells (18 percent) show a decreasing nitrate concentration trend, and 11 wells (64 percent) show no nitrate concentration trend. Six wells (35 percent) currently exceed the U.S. Environmental Protection Agency's maximum contaminant limit of 10 milligrams per liter for nitrate (nitrite plus nitrate, measured as nitrogen).

  19. Total Phosphorus Concentration Trends in 40 Iowa Rivers, 1999 to 2013.

    PubMed

    Wang, Chao; Chan, Kung-Sik; Schilling, Keith E

    2016-07-01

    Excessive phosphorus (P) in rivers is prompting states to develop strategies to reduce P concentrations and export. The goal of this study was to assess the current condition by analyzing trends in total P (TP) concentrations at 40 river monitoring sites in Iowa for the period 1998 to 2013. We used monthly river monitoring data collected by the State of Iowa at ambient sites located beyond the influence of point sources or cities. Study objectives were to assess the presence of any linear trends in the TP concentration data using a time-series method that accounted for temporal correlation in the data and discharge and to combine the trend information from individual sites into an assessment of the statewide rate of change in river TP concentrations. Results indicated that annual TP concentrations were significantly decreasing at 12 sites ( < 0.05), with concentrations ranging from 7.5% (Maple River) to 2.6% (Boyer River) and averaging 4.1% for the 12 sites. No statistically significant change was measured at 28 sites ( > 0.05), although all but four of these sites had decreasing concentrations. As a population of sampled rivers across Iowa, TP concentrations were declining at an annual rate of approximately 2.6%. The decreasing trends are consistent with reported reductions in sediment concentrations measured in the Raccoon River and with decreasing trends detected in other midwestern rivers. We attribute the decreasing TP trends primarily to improvements in conservation and land management. Although reducing nonpoint source TP concentrations in Iowa rivers will be a tremendous challenge for the agricultural community, progress is being made toward meeting this goal with existing programs.

  20. Total Phosphorus Concentration Trends in 40 Iowa Rivers, 1999 to 2013.

    PubMed

    Wang, Chao; Chan, Kung-Sik; Schilling, Keith E

    2016-07-01

    Excessive phosphorus (P) in rivers is prompting states to develop strategies to reduce P concentrations and export. The goal of this study was to assess the current condition by analyzing trends in total P (TP) concentrations at 40 river monitoring sites in Iowa for the period 1998 to 2013. We used monthly river monitoring data collected by the State of Iowa at ambient sites located beyond the influence of point sources or cities. Study objectives were to assess the presence of any linear trends in the TP concentration data using a time-series method that accounted for temporal correlation in the data and discharge and to combine the trend information from individual sites into an assessment of the statewide rate of change in river TP concentrations. Results indicated that annual TP concentrations were significantly decreasing at 12 sites ( < 0.05), with concentrations ranging from 7.5% (Maple River) to 2.6% (Boyer River) and averaging 4.1% for the 12 sites. No statistically significant change was measured at 28 sites ( > 0.05), although all but four of these sites had decreasing concentrations. As a population of sampled rivers across Iowa, TP concentrations were declining at an annual rate of approximately 2.6%. The decreasing trends are consistent with reported reductions in sediment concentrations measured in the Raccoon River and with decreasing trends detected in other midwestern rivers. We attribute the decreasing TP trends primarily to improvements in conservation and land management. Although reducing nonpoint source TP concentrations in Iowa rivers will be a tremendous challenge for the agricultural community, progress is being made toward meeting this goal with existing programs. PMID:27380084

  1. Study of temporal trends in mercury concentrations in the primary flight feathers of Strix aluco.

    PubMed

    Varela, Z; García-Seoane, R; Fernández, J A; Carballeira, A; Aboal, J R

    2016-08-01

    Temporal trends in Hg concentrations were determined in the primary flight feathers of 146 specimens of Strix aluco which had died in various Wildlife Recovery Centres in Galicia (NW Spain) between 1997 and 2014. The aim of the study was to determine whether standardization of a primary flight feather (or feathers) in this species is essential for identifying temporal trends in Hg concentrations. For this purpose, we had to first standardize the feather(s) analyzed to enable comparison of the levels of Hg detected in different feathers. The results show a high degree of both inter and intra-individual variability but despite that, it was possible to identify P5 as the most representative feather taking into account the amount of metal excreted in each feather and the intra-individual variability: its median was 133ng, which represents 15% (from 7% to 15%) of the total Hg present in all the primary feathers. However, this "standard feather" did not reveal any temporal trend in Hg concentrations for the study period. This lack of trend was found irrespective of the feather considered and it is expected that detection of any existing trend would also not depend on the feather considered. We conclude that use of any particular feather is not essential for identifying temporal trends in Hg concentrations, because the pattern will be identified regardless of the feather selected.

  2. Trends in pesticide concentrations in streams of the western United States, 1993-2005

    USGS Publications Warehouse

    Johnson, H.M.; Domagalski, J.L.; Saleh, D.K.

    2011-01-01

    Trends in pesticide concentrations for 15 streams in California, Oregon, Washington, and Idaho were determined for the organophosphate insecticides chlorpyrifos and diazinon and the herbicides atrazine, s-ethyl diproplythiocarbamate (EPTC), metolachlor, simazine, and trifluralin. A parametric regression model was used to account for flow, seasonality, and antecedent hydrologic conditions and thereby estimate trends in pesticide concentrations in streams arising from changes in use amount and application method in their associated catchments. Decreasing trends most often were observed for diazinon, and reflect the shift to alternative pesticides by farmers, commercial applicators, and homeowners because of use restrictions and product cancelation. Consistent trends were observed for several herbicides, including upward trends in simazine at urban-influenced sites from 2000 to 2005, and downward trends in atrazine and EPTC at agricultural sites from the mid-1990s to 2005. The model provided additional information about pesticide occurrence and transport in the modeled streams. Two examples are presented and briefly discussed: (1) timing of peak concentrations for individual compounds varied greatly across this geographic gradient because of different application periods and the effects of local rain patterns, irrigation, and soil drainage and (2) reconstructions of continuous diazinon concentrations at sites in California are used to evaluate compliance with total maximum daily load targets.

  3. Trends in Pesticide Concentrations in Streams of the Western United States, 1993-20051

    PubMed Central

    Johnson, Henry M; Domagalski, Joseph L; Saleh, Dina K

    2011-01-01

    Trends in pesticide concentrations for 15 streams in California, Oregon, Washington, and Idaho were determined for the organophosphate insecticides chlorpyrifos and diazinon and the herbicides atrazine, s-ethyl diproplythiocarbamate (EPTC), metolachlor, simazine, and trifluralin. A parametric regression model was used to account for flow, seasonality, and antecedent hydrologic conditions and thereby estimate trends in pesticide concentrations in streams arising from changes in use amount and application method in their associated catchments. Decreasing trends most often were observed for diazinon, and reflect the shift to alternative pesticides by farmers, commercial applicators, and homeowners because of use restrictions and product cancelation. Consistent trends were observed for several herbicides, including upward trends in simazine at urban-influenced sites from 2000 to 2005, and downward trends in atrazine and EPTC at agricultural sites from the mid-1990s to 2005. The model provided additional information about pesticide occurrence and transport in the modeled streams. Two examples are presented and briefly discussed: (1) timing of peak concentrations for individual compounds varied greatly across this geographic gradient because of different application periods and the effects of local rain patterns, irrigation, and soil drainage and (2) reconstructions of continuous diazinon concentrations at sites in California are used to evaluate compliance with total maximum daily load targets. PMID:22457570

  4. Preliminary investigation of radon concentration in surface water and drinking water in Shenzhen City, South China.

    PubMed

    Li, Ting; Wang, Nanping; Li, Shijun

    2015-11-01

    A radon survey in surface water and drinking water was conducted using a portable degassing system associated with an ionisation chamber AlphaGUARD (PQ2000) for understanding levels of dissolved radon ((222)Rn) concentration in different types of water sources and risk assessment of radon in drinking water in Shenzhen City (SC) with a population of 10 628 900 in 2013, Guangdong Province of China. The measurements show that arithmetic means ± standard deviations of radon ((222)Rn) concentration are 52.05 ± 6.64, 0.29 ± 0.26, 0.15 ± 0.23 and 0.37 ± 0.42 kBq m(-3) in spring water, surface water, large and small public water supplies, respectively. Only radon concentrations of two water samples collected in mountainous areas are more than 11.10 kBq m(-3), exceeding the limit of radon concentration in drinking water stipulated by the national standard of China (GB5749-2006). The annual effective doses due to radon in drinking water were also calculated. The investigation suggests that there are no risks caused by radon in the drinking water in SC.

  5. Preliminary investigation of radon concentration in surface water and drinking water in Shenzhen City, South China.

    PubMed

    Li, Ting; Wang, Nanping; Li, Shijun

    2015-11-01

    A radon survey in surface water and drinking water was conducted using a portable degassing system associated with an ionisation chamber AlphaGUARD (PQ2000) for understanding levels of dissolved radon ((222)Rn) concentration in different types of water sources and risk assessment of radon in drinking water in Shenzhen City (SC) with a population of 10 628 900 in 2013, Guangdong Province of China. The measurements show that arithmetic means ± standard deviations of radon ((222)Rn) concentration are 52.05 ± 6.64, 0.29 ± 0.26, 0.15 ± 0.23 and 0.37 ± 0.42 kBq m(-3) in spring water, surface water, large and small public water supplies, respectively. Only radon concentrations of two water samples collected in mountainous areas are more than 11.10 kBq m(-3), exceeding the limit of radon concentration in drinking water stipulated by the national standard of China (GB5749-2006). The annual effective doses due to radon in drinking water were also calculated. The investigation suggests that there are no risks caused by radon in the drinking water in SC. PMID:25904699

  6. Trends in soil solution dissolved organic carbon (DOC) concentrations across European forests

    NASA Astrophysics Data System (ADS)

    Camino-Serrano, Marta; Graf Pannatier, Elisabeth; Vicca, Sara; Luyssaert, Sebastiaan; Jonard, Mathieu; Ciais, Philippe; Guenet, Bertrand; Gielen, Bert; Peñuelas, Josep; Sardans, Jordi; Waldner, Peter; Etzold, Sophia; Cecchini, Guia; Clarke, Nicholas; Galić, Zoran; Gandois, Laure; Hansen, Karin; Johnson, Jim; Klinck, Uwe; Lachmanová, Zora; Lindroos, Antti-Jussi; Meesenburg, Henning; Nieminen, Tiina M.; Sanders, Tanja G. M.; Sawicka, Kasia; Seidling, Walter; Thimonier, Anne; Vanguelova, Elena; Verstraeten, Arne; Vesterdal, Lars; Janssens, Ivan A.

    2016-10-01

    Dissolved organic carbon (DOC) in surface waters is connected to DOC in soil solution through hydrological pathways. Therefore, it is expected that long-term dynamics of DOC in surface waters reflect DOC trends in soil solution. However, a multitude of site studies have failed so far to establish consistent trends in soil solution DOC, whereas increasing concentrations in European surface waters over the past decades appear to be the norm, possibly as a result of recovery from acidification. The objectives of this study were therefore to understand the long-term trends of soil solution DOC from a large number of European forests (ICP Forests Level II plots) and determine their main physico-chemical and biological controls. We applied trend analysis at two levels: (1) to the entire European dataset and (2) to the individual time series and related trends with plot characteristics, i.e., soil and vegetation properties, soil solution chemistry and atmospheric deposition loads. Analyses of the entire dataset showed an overall increasing trend in DOC concentrations in the organic layers, but, at individual plots and depths, there was no clear overall trend in soil solution DOC. The rate change in soil solution DOC ranged between -16.8 and +23 % yr-1 (median = +0.4 % yr-1) across Europe. The non-significant trends (40 %) outnumbered the increasing (35 %) and decreasing trends (25 %) across the 97 ICP Forests Level II sites. By means of multivariate statistics, we found increasing trends in DOC concentrations with increasing mean nitrate (NO3-) deposition and increasing trends in DOC concentrations with decreasing mean sulfate (SO42-) deposition, with the magnitude of these relationships depending on plot deposition history. While the attribution of increasing trends in DOC to the reduction of SO42- deposition could be confirmed in low to medium N deposition areas, in agreement with observations in surface waters, this was not the case in high N deposition areas. In

  7. Water quality in Indiana: trends in concentrations of selected nutrients, metals, and ions in streams, 2000-10

    USGS Publications Warehouse

    Risch, Martin R.; Bunch, Aubrey R.; Vecchia, Skip V.; Martin, Jeffrey D.; Baker, Nancy T.

    2014-01-01

    Statistically significant trends were identified that included 167 downward trends and 83 upward trends. The Kankakee River Basin had the most significant upward trends while the most significant downward trends were in the Whitewater River Basin, the Lake Michigan Basin, and the Patoka River Basin. For most constituents, a majority of sites had significant downward trends. Two streams in the Lake Michigan Basin have shown substantial decreases in most constituents. The West Fork White River near Indianapolis, Indiana, showed increases in nitrate and phosphorus and the Kankakee River Basin showed increases in copper, zinc, chloride, sulfate, and hardness. Upward trends in nutrients were identified at a few sites, but most nutrient trends were downward. Upward trends in metals corresponded with relatively small concentration increases while downward trends involved considerably larger concentration changes. Downward trends in chloride, sulfate, and suspended solids were observed statewide, but upward trends in hardness were observed in the northern half of Indiana.

  8. Spatiotemporal Trends Analysis of Pyrethroid Sediment Concentrations Spanning 10 Years in a Residential Creek in California.

    PubMed

    Hall, Lenwood W; Anderson, Ronald D; Killen, William D

    2016-02-01

    The objective of this study was to assess temporal and spatial trends for eight pyrethroids monitored in sediment spanning 10 years from 2006 to 2015 in a residential stream in California (Pleasant Grove Creek). The timeframe for this study included sampling 3 years during a somewhat normal non-drought period (2006-2008) and 3 years during a severe drought period (2013-2015). Regression analysis of pyrethroid concentrations in Pleasant Grove Creek for 2006, 2007, 2008, 2012, 2013, 2014, and 2015 using ½ the detection limit for nondetected concentrations showed statistically significant declining trends for cyfluthrin, cypermethrin, deltamethrin, permethrin, and total pyrethoids. Additional trends analysis of the Pleasant Grove Creek pyrethroid data using only measured concentrations, without nondetected values, showed similar statistically significant declining trends for cyfluthrin, cypermethrin, deltamethrin, esfenvalerate, fenpropathrin, permethrin, and total pyrethroids. Spatial trends analysis for the specific creek sites showed that six of the eight pyrethroids had a greater number of sites with statistically significant declining concentrations. Possible reasons for reduced pyrethroid concentrations in the stream bed in Pleasant Grove Creek during this 10-year period are label changes in 2012 that reduced residential use and lack of precipitation during the later severe drought years of 2013-2015. PMID:26643307

  9. Trends in PM2.5 emissions, concentrations and apportionments in Detroit and Chicago

    NASA Astrophysics Data System (ADS)

    Milando, Chad; Huang, Lei; Batterman, Stuart

    2016-03-01

    PM2.5 concentrations throughout much of the U.S. have decreased over the last 15 years, but emissions and concentration trends can vary by location and source type. Such trends should be understood to inform air quality management and policies. This work examines trends in emissions, concentrations and source apportionments in two large Midwest U.S. cities, Detroit, Michigan, and Chicago, Illinois. Annual and seasonal trends were investigated using National Emission Inventory (NEI) data for 2002 to 2011, speciated ambient PM2.5 data from 2001 to 2014, apportionments from positive matrix factorization (PMF) receptor modeling, and quantile regression. Over the study period, county-wide data suggest emissions from point sources decreased (Detroit) or held constant (Chicago), while emissions from on-road mobile sources were constant (Detroit) or increased (Chicago), however changes in methodology limit the interpretation of inventory trends. Ambient concentration data also suggest source and apportionment trends, e.g., annual median concentrations of PM2.5 in the two cities declined by 3.2-3.6%/yr (faster than national trends), and sulfate concentrations (due to coal-fired facilities and other point source emissions) declined even faster; in contrast, organic and elemental carbon (tracers of gasoline and diesel vehicle exhaust) declined more slowly or held constant. The PMF models identified nine sources in Detroit and eight in Chicago, the most important being secondary sulfate, secondary nitrate and vehicle emissions. A minor crustal dust source, metals sources, and a biomass source also were present in both cities. These apportionments showed that the median relative contributions from secondary sulfate sources decreased by 4.2-5.5% per year in Detroit and Chicago, while contributions from metals sources, biomass sources, and vehicles increased from 1.3 to 9.2% per year. This first application of quantile regression to trend analyses of speciated PM2.5 data reveals

  10. Recent trends in chloride and sodium concentrations in the deep subalpine lakes (Northern Italy).

    PubMed

    Rogora, Michela; Mosello, Rosario; Kamburska, Lyudmila; Salmaso, Nico; Cerasino, Leonardo; Leoni, Barbara; Garibaldi, Letizia; Soler, Valentina; Lepori, Fabio; Colombo, Luca; Buzzi, Fabio

    2015-12-01

    A growing concern exists about the effects of chloride (Cl) on freshwater systems. Increasing Cl concentrations have been observed in the last few decades in several rivers and lakes, mainly in northern countries. In Italy, present levels and temporal changes of sodium (Na) and Cl in water bodies have rarely been assessed. Based on long-term data for the lakes of the subalpine district in Italy (Maggiore, Lugano, Como, Iseo, Garda), we analyzed trends affecting Cl and Na concentrations during the last 25 years, with the aim of identifying temporal changes and assessing possible causes. An in-depth analysis is presented for Lake Maggiore. Positive temporal Na and Cl trends were evident in all studied lakes, with the trends increasing since early 2000s. Data for Lake Maggiore tributaries showed a clear seasonality (higher values in winter and early spring). The NaCl used as road de-icing agent, together with Cl discharge from wastewater treatment plants, were identified as the main causes for the observed trends. Chloride concentrations in the lakes are below the threshold limit for reduced water quality and below concentrations known to harm aquatic biota. However, considering the relevance of deep subalpine lakes, representing almost 80% of the total freshwater volume in Italy, these trends indicate an important chemical change, which warrants further analysis.

  11. Recent trends in chloride and sodium concentrations in the deep subalpine lakes (Northern Italy).

    PubMed

    Rogora, Michela; Mosello, Rosario; Kamburska, Lyudmila; Salmaso, Nico; Cerasino, Leonardo; Leoni, Barbara; Garibaldi, Letizia; Soler, Valentina; Lepori, Fabio; Colombo, Luca; Buzzi, Fabio

    2015-12-01

    A growing concern exists about the effects of chloride (Cl) on freshwater systems. Increasing Cl concentrations have been observed in the last few decades in several rivers and lakes, mainly in northern countries. In Italy, present levels and temporal changes of sodium (Na) and Cl in water bodies have rarely been assessed. Based on long-term data for the lakes of the subalpine district in Italy (Maggiore, Lugano, Como, Iseo, Garda), we analyzed trends affecting Cl and Na concentrations during the last 25 years, with the aim of identifying temporal changes and assessing possible causes. An in-depth analysis is presented for Lake Maggiore. Positive temporal Na and Cl trends were evident in all studied lakes, with the trends increasing since early 2000s. Data for Lake Maggiore tributaries showed a clear seasonality (higher values in winter and early spring). The NaCl used as road de-icing agent, together with Cl discharge from wastewater treatment plants, were identified as the main causes for the observed trends. Chloride concentrations in the lakes are below the threshold limit for reduced water quality and below concentrations known to harm aquatic biota. However, considering the relevance of deep subalpine lakes, representing almost 80% of the total freshwater volume in Italy, these trends indicate an important chemical change, which warrants further analysis. PMID:26233742

  12. Trends in atmospheric ammonium concentrations in relation to atmospheric sulfate and local agriculture.

    PubMed

    Kelly, Victoria R; Lovett, Gary M; Weathers, Kathleen C; Likens, Gene E

    2005-06-01

    Ammonium (NH(4)(+)) concentrations in air and precipitation at the Institute of Ecosystem Studies (IES) in southeastern New York, USA declined over an 11-year period from 1988 to 1999, but increased from 1999 to 2001. These trends in particulate NH(4)(+) correlated well with trends in particulate SO(4)(2-) over the 1988-2001 period. The NH(4)(+) trends were not as well correlated with local cattle and milk production, which declined continuously throughout the period. This suggests that regional transport of SO(4)(2-) may have a greater impact on concentrations of NH(4)(+) and subsequent deposition than local agricultural emissions of NH(3). Ammonium concentrations in precipitation correlated significantly with precipitation SO(4)(2-) concentrations for the 1984-2001 period although NH(4)(+) in precipitation increased after 1999 and SO(4)(2-) in precipitation continued to decline after 1999. The correlation between NH(4)(+) and SO(4)(2-) was stronger for particulates than for precipitation. Particulate NH(4)(+) concentrations were also correlated with particulate SO(4)(2-) concentrations at 31 of 35 eastern U.S. CASTNet sites that had at least 10 years of data. Air concentrations of NH(4)(+) and SO(4)(2-) were more strongly correlated at the sites that were located within an agricultural landscape than in forested sites. At most of the sites there was either no trend or a decrease in NH(4)(+) dry deposition during the 1988-2001 period. The sites that showed an increasing trend in NH(4)(+) dry deposition were generally located in the southeastern U.S. The results of this study suggest that, in the northeastern U.S., air concentrations of NH(4)(+) and subsequent deposition may be more closely linked to SO(4)(2-) and thus SO(2) emissions than with NH(3) emissions. These results also suggest that reductions in S emissions have reduced NH(4)(+) transport to and NH(4)(+)-N deposition in the Northeast.

  13. Trends in elemental concentrations of fine particles at remote sites in the United States of America

    NASA Astrophysics Data System (ADS)

    Eldred, Robert A.; Cahill, Thomas A.

    The University of California at Davis has been monitoring particulate concentrations in remote sites throughout the United States of America since 1979 in networks operated for the National Park Service and the Environmental Protection Agency. Twelve sites in remote class I visibility areas have almost complete records from June 1982 to August 1992, seven in the southwest, three in the northwest, and two in the east. During this period, two samples of fine particles (0-2.5 μm) on Teflon filters were collected every week and analysed for elemental concentration by Particle Induced X-ray Emission (PIXE). This paper will examine the historical trends for sulfur, zinc, lead, and the soil elements. Measurements during the past four years have verified that the sulfur is present as sulfate. In the southwest, 80% of the sulfur trends in spring, summer and fall decreased, while most of the winter trends increased. The annual trends decreased at six of the seven sites. The trends in the northwest increased slightly. The two eastern sites had the most important trends, with significant increases of almost 4% per year in summer, 1-3% increases in spring and fall, and 2% decreases in winter. The annual increases were between 2 and 3%. Generally there were no significant trends for zinc and the soil elements. Lead at all sites decreased sharply through 1986, corresponding to the shift to unleaded gasoline, but has since leveled off at around 18% of the 1982 means. The most important conclusion of this study is that through the use of stable sampling and analytical protocols, we have been able to determine statistically significant historical trends of as small as 1-2% per year for sites with 10-year records.

  14. Trends in suspended-sediment concentration at selected stream sites in Kansas, 1970-2002

    USGS Publications Warehouse

    Putnam, James E.; Pope, Larry M.

    2003-01-01

    Knowledge of erosion, transport, and deposition of sediment relative to streams and impoundments is important to those involved directly or indirectly in the development and management of water resources. Monitoring the quantity of sediment in streams and impoundments is important because: (1) sediment may degrade the water quality of streams for such uses as municipal water supply, (2) sediment is detrimental to the health of some species of aquatic animals and plants, and (3) accumulation of sediment in water-supply impoundments decreases the amount of storage and, therefore, water available for users. One of the objectives of the Kansas Water Plan is to reduce the amount of sediment in Kansas streams by 2010. During the last 30 years, millions of dollars have been spent in Kansas watersheds to reduce sediment transport to streams. Because the last evaluation of trends in suspended-sediment concentrations in Kansas was completed in 1985, 14 sediment sampling sites that represent 10 of the 12 major river basins in Kansas were reestablished in 2000. The purpose of this report is to present the results of time-trend analyses at the reestablished sediment data-collection sites for the period of about 1970?2002 and to evaluate changes in the watersheds that may explain the trends. Time-trend tests for 13 of 14 sediment sampling sites in Kansas for the period from about 1970 to 2002 indicated that 3 of the 13 sites tested had statistically significant decreasing suspended-sediment concentrations; however, only 2 sites, Walnut River at Winfield and Elk River at Elk Falls, had trends that were statistically significant at the 0.05 probability level. Increasing suspended-sediment concentrations were indicated at three sites although none were statistically significant at the 0.05 probability level. Samples from five of the six sampling sites located upstream from reservoirs indicated decreasing suspended-sediment concentrations. Watershed impoundments located in the

  15. Trends in polycyclic aromatic hydrocarbon concentrations in the Great Lakes atmosphere

    SciTech Connect

    Ping Sun; Pierrette Blanchard; Kenneth A. Brice; Ronald A. Hites

    2006-10-15

    Atmospheric polycyclic aromatic hydrocarbon (PAHs) concentrations were measured in both the vapor and particle phases at seven sites near the Great Lakes as a part of the Integrated Atmospheric Deposition Network. Lower molecular weight PAHs, including fluorene, phenanthrene, fluoranthrene, and pyrene, were dominant in the vapor phase, and higher molecular weight PAHs, including chrysene, benzo(a)pyrene, and coronene, were dominant in the particle phase. The highest PAH concentrations in both the vapor and particle phases were observed in Chicago followed by the semiurban site at Sturgeon Point, NY. The major sources of PAHs in and around Chicago are vehicle emissions, coal and natural gas combustion, and coke production. The spatial difference of PAH concentrations can be explained by the local population density. Long-term decreasing trends of most PAH concentrations were observed in both the vapor and particle phases at Chicago, with half-lives ranging from 3-10 years in the vapor phase and 5-15 years in the particle phase. At Eagle Harbor, Sleeping Bear Dunes, and Sturgeon Point, total PAH concentrations in the vapor phase showed significant, but slow, long-term decreasing trends. At the Sturgeon Point site, which was impacted by a nearby city, particle-phase PAH concentrations also declined. However, most particle-phase PAH concentrations did not show significant long-term decreasing trends at the remote sites. Seasonal trends were also observed for particle-phase PAH concentrations, which were higher in the winter and lower in the summer. 36 refs., 4 figs., 1 tab.

  16. Quantifying Main Trends in Lysozyme Nucleation: The Effects of Precipitant Concentration, Supersaturation and Impurities

    NASA Technical Reports Server (NTRS)

    Burke, Michael W.; Leardi, Riccardo; Judge, Russell A.; Pusey, Marc L.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    Full factorial experimental design incorporating multi-linear regression analysis of the experimental data allows quick identification of main trends and effects using a limited number of experiments. In this study these techniques were employed to identify the effect of precipitant concentration, supersaturation, and the presence of an impurity, the physiological lysozyme dimer, on the nucleation rate and crystal dimensions of the tetragonal forin of chicken egg white lysozyme. Decreasing precipitant concentration, increasing supers aturation, and increasing impurity, were found to increase crystal numbers. The crystal axial ratio decreased with increasing precipitant concentration, independent of impurity.

  17. Quantifying Main Trends in Lysozyme Nucleation: The Effect of Precipitant Concentration and Impurities

    NASA Technical Reports Server (NTRS)

    Burke, Michael W.; Judge, Russell A.; Pusey, Marc L.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    Full factorial experiment design incorporating multi-linear regression analysis of the experimental data allows the main trends and effects to be quickly identified while using only a limited number of experiments. These techniques were used to identify the effect of precipitant concentration and the presence of an impurity, the physiological lysozyme dimer, on the nucleation rate and crystal dimensions of the tetragonal form of chicken egg white lysozyme. Increasing precipitant concentration was found to decrease crystal numbers, the magnitude of this effect also depending on the supersaturation. The presence of the dimer generally increased nucleation. The crystal axial ratio decreased with increasing precipitant concentration independent of impurity.

  18. Trends in ocean colour and chlorophyll concentration from 1889 to 2000, worldwide.

    PubMed

    Wernand, Marcel R; van der Woerd, Hendrik J; Gieskes, Winfried W C

    2013-01-01

    Marine primary productivity is an important agent in the global cycling of carbon dioxide, a major 'greenhouse gas', and variations in the concentration of the ocean's phytoplankton biomass can therefore explain trends in the global carbon budget. Since the launch of satellite-mounted sensors globe-wide monitoring of chlorophyll, a phytoplankton biomass proxy, became feasible. Just as satellites, the Forel-Ule (FU) scale record (a hardly explored database of ocean colour) has covered all seas and oceans--but already since 1889. We provide evidence that changes of ocean surface chlorophyll can be reconstructed with confidence from this record. The EcoLight radiative transfer numerical model indicates that the FU index is closely related to chlorophyll concentrations in open ocean regions. The most complete FU record is that of the North Atlantic in terms of coverage over space and in time; this dataset has been used to test the validity of colour changes that can be translated to chlorophyll. The FU and FU-derived chlorophyll data were analysed for monotonously increasing or decreasing trends with the non-parametric Mann-Kendall test, a method to establish the presence of a consistent trend. Our analysis has not revealed a globe-wide trend of increase or decrease in chlorophyll concentration during the past century; ocean regions have apparently responded differentially to changes in meteorological, hydrological and biological conditions at the surface, including potential long-term trends related to global warming. Since 1889, chlorophyll concentrations have decreased in the Indian Ocean and in the Pacific; increased in the Atlantic Ocean, the Mediterranean, the Chinese Sea, and in the seas west and north-west of Japan. This suggests that explanations of chlorophyll changes over long periods should focus on hydrographical and biological characteristics typical of single ocean regions, not on those of 'the' ocean.

  19. Trends in Ocean Colour and Chlorophyll Concentration from 1889 to 2000, Worldwide

    PubMed Central

    Wernand, Marcel R.; van der Woerd, Hendrik J.; Gieskes, Winfried W. C.

    2013-01-01

    Marine primary productivity is an important agent in the global cycling of carbon dioxide, a major ‘greenhouse gas’, and variations in the concentration of the ocean's phytoplankton biomass can therefore explain trends in the global carbon budget. Since the launch of satellite-mounted sensors globe-wide monitoring of chlorophyll, a phytoplankton biomass proxy, became feasible. Just as satellites, the Forel-Ule (FU) scale record (a hardly explored database of ocean colour) has covered all seas and oceans – but already since 1889. We provide evidence that changes of ocean surface chlorophyll can be reconstructed with confidence from this record. The EcoLight radiative transfer numerical model indicates that the FU index is closely related to chlorophyll concentrations in open ocean regions. The most complete FU record is that of the North Atlantic in terms of coverage over space and in time; this dataset has been used to test the validity of colour changes that can be translated to chlorophyll. The FU and FU-derived chlorophyll data were analysed for monotonously increasing or decreasing trends with the non-parametric Mann-Kendall test, a method to establish the presence of a consistent trend. Our analysis has not revealed a globe-wide trend of increase or decrease in chlorophyll concentration during the past century; ocean regions have apparently responded differentially to changes in meteorological, hydrological and biological conditions at the surface, including potential long-term trends related to global warming. Since 1889, chlorophyll concentrations have decreased in the Indian Ocean and in the Pacific; increased in the Atlantic Ocean, the Mediterranean, the Chinese Sea, and in the seas west and north-west of Japan. This suggests that explanations of chlorophyll changes over long periods should focus on hydrographical and biological characteristics typical of single ocean regions, not on those of ‘the’ ocean. PMID:23776435

  20. Trends in ocean colour and chlorophyll concentration from 1889 to 2000, worldwide.

    PubMed

    Wernand, Marcel R; van der Woerd, Hendrik J; Gieskes, Winfried W C

    2013-01-01

    Marine primary productivity is an important agent in the global cycling of carbon dioxide, a major 'greenhouse gas', and variations in the concentration of the ocean's phytoplankton biomass can therefore explain trends in the global carbon budget. Since the launch of satellite-mounted sensors globe-wide monitoring of chlorophyll, a phytoplankton biomass proxy, became feasible. Just as satellites, the Forel-Ule (FU) scale record (a hardly explored database of ocean colour) has covered all seas and oceans--but already since 1889. We provide evidence that changes of ocean surface chlorophyll can be reconstructed with confidence from this record. The EcoLight radiative transfer numerical model indicates that the FU index is closely related to chlorophyll concentrations in open ocean regions. The most complete FU record is that of the North Atlantic in terms of coverage over space and in time; this dataset has been used to test the validity of colour changes that can be translated to chlorophyll. The FU and FU-derived chlorophyll data were analysed for monotonously increasing or decreasing trends with the non-parametric Mann-Kendall test, a method to establish the presence of a consistent trend. Our analysis has not revealed a globe-wide trend of increase or decrease in chlorophyll concentration during the past century; ocean regions have apparently responded differentially to changes in meteorological, hydrological and biological conditions at the surface, including potential long-term trends related to global warming. Since 1889, chlorophyll concentrations have decreased in the Indian Ocean and in the Pacific; increased in the Atlantic Ocean, the Mediterranean, the Chinese Sea, and in the seas west and north-west of Japan. This suggests that explanations of chlorophyll changes over long periods should focus on hydrographical and biological characteristics typical of single ocean regions, not on those of 'the' ocean. PMID:23776435

  1. Indoor radon concentration in geothermal areas of central Italy.

    PubMed

    Ciolini, R; Mazed, D

    2010-09-01

    The indoor radon ((222)Rn) activity concentration was measured between January and June in the schools of two geothermal areas in Tuscany, central Italy. One of these areas (the Larderello area) is characterized by a large number of geothermal power plants, covering about 9% of the world's geothermal power production. In contrast, the other area, Monte Pisano, has not any such facilities. About 250 measurements were made using track etch detectors. Only a slight difference in the concentrations between the two major sampling areas (98 Bq m(-3) for Larderello area and 43 Bq m(-3) for Monte Pisano area) was found, and this was related to different geological characteristics of the ground and not the presence of the geothermal plants. The measured radon concentrations were always well below the intervention levels in both areas, and health risks for students and personnel in the examined schools were excluded.

  2. Temporal trends in and influence of wind on PAH concentrations measured near the Great Lakes

    SciTech Connect

    Cortes, D.R.; Basu, I.; Sweet, C.W.; Hites, R.A.

    2000-02-01

    This paper reports on temporal trends in gas- and particle-phase PAH concentrations measured at three sites in the Great Lakes' Integrated Atmospheric Deposition Network: Eagle Harbor, near Lake Superior, Sleeping Bear Dunes, near Lake Michigan, and Sturgeon Point, near Lake Erie. While gas-phase concentrations have been decreasing since 1991 at all sites, particle-phase concentrations have been decreasing only at Sleeping Bear Dunes. To determine whether these results represent trends in background levels or regional emissions, the average concentrations are compared to those found in urban and rural studies. In addition, the influence of local wind direction on PAH concentrations is investigated, with the assumption that dependence on wind direction implies regional sources. Using these two methods, it is found that PAH concentrations at Eagle Harbor and Sleeping Bear Dunes represent regional background levels but that PAH from the Buffalo Region intrude on the background levels measured at the Sturgeon Point site. At this site, wind from over Lake Erie reduces local PAH concentrations.

  3. Regional analysis of groundwater nitrate concentrations and trends in Denmark in regard to agricultural influence

    NASA Astrophysics Data System (ADS)

    Hansen, B.; Dalgaard, T.; Thorling, L.; Sørensen, B.; Erlandsen, M.

    2012-08-01

    The act of balancing between an intensive agriculture with a high potential for nitrate pollution and a drinking water supply almost entirely based on groundwater is a challenge faced by Denmark and similar regions around the globe. Since the 1980s, regulations implemented by Danish farmers have succeeded in optimizing the N (nitrogen) management at farm level. As a result, the upward agricultural N surplus trend has been reversed, and the N surplus has reduced by 30-55% from 1980 to 2007 depending on region. The reduction in the N surplus served to reduce the losses of N from agriculture, with documented positive effects on nature and the environment in Denmark. In groundwater, the upward trend in nitrate concentrations was reversed around 1980, and a larger number of downward nitrate trends were seen in the youngest groundwater compared with the oldest groundwater. However, on average, approximately 48% of the oxic monitored groundwater has nitrate concentrations above the groundwater and drinking water standards of 50 mg l-1. Furthermore, trend analyses show that 33% of all the monitored groundwater has upward nitrate trends, while only 18% of the youngest groundwater has upward nitrate trends according to data sampled from 1988-2009. A regional analysis shows a correlation between a high level of N surplus in agriculture, high concentrations of nitrate in groundwater and the largest number of downward nitrate trends in groundwater in the livestock-dense northern and western parts of Denmark compared with the southeastern regions with lower livestock densities. These results indicate that the livestock farms dominating in northern and western parts of Denmark have achieved the largest reductions in N surpluses. Groundwater recharge age determinations allow comparison of long-term changes in N surplus in agriculture with changes in oxic groundwater quality. The presented data analysis is based on groundwater recharged from 1952-2003, but sampled from 1988

  4. Regional analysis of groundwater nitrate concentrations and trends in Denmark in regard to agricultural influence

    NASA Astrophysics Data System (ADS)

    Hansen, B.; Dalgaard, T.; Thorling, L.; Sørensen, B.; Erlandsen, M.

    2012-05-01

    The act of balancing between an intensive agriculture with a high potential for nitrate pollution and a~drinking water supply almost entirely based on groundwater is a challenge faced by Denmark and similar regions around the globe. Since the 1980s, regulations implemented by Danish farmers have succeeded in optimizing the N (nitrogen) management at farm level. As a result, the upward agricultural N surplus trend has been reversed, and the N surplus has reduced by 30-55 % from 1980 to 2007 depending on region. The reduction in the N surplus served to reduce the losses of N from agriculture, with documented positive effects on nature and the environment in Denmark. In groundwater, the upward trend in nitrate concentration was reversed around 1980, and a larger number of downward nitrate trends were seen in the youngest groundwater compared with the oldest groundwater. However, on average, approximately 48 % of the oxic monitored groundwater has nitrate concentrations above the groundwater and drinking water standards of 50 mg l-1. Furthermore, trend analyses show that 33 % of all the monitored groundwater has upward nitrate trends, while only 18 % of the youngest groundwater has upward nitrate trends according to data sampled from 1988-2009. A regional analysis shows a correlation between a high level of N surplus in agriculture, high concentrations of nitrate in groundwater and the largest number of downward nitrate trends in groundwater in the livestock-dense northern and western parts of Denmark compared with the south-eastern regions with lower livestock densities. These results indicate that the livestock farms dominating in northern and western parts of Denmark have achieved the largest reductions in N surpluses. Groundwater recharge age determinations allow comparison of long-term changes in N surplus in agriculture with changes in oxic groundwater quality. The presented data analysis is based on groundwater recharged from 1952-2003, but sampled from 1988

  5. Trends and threshold exceedances analysis of airborne pollen concentrations in Metropolitan Santiago Chile

    PubMed Central

    Toro A., Richard; Córdova J., Alicia; Canales, Mauricio; Morales S., Raul G. E.; Mardones P., Pedro; Leiva G., Manuel A.

    2015-01-01

    Pollen is one of the primary causes of allergic rhinoconjunctivitis in urban centers. In the present study, the concentrations of 39 different pollens in the Santiago de Chile metropolitan area over the period 2009–2013 are characterized. The pollen was monitored daily using Burkard volumetric equipment. The contribution of each type of pollen and the corresponding time trends are evaluated. The concentrations of the pollens are compared with the established threshold levels for the protection of human health. The results show that the total amount of pollen grains originating from trees, grasses, weeds and indeterminate sources throughout the period of the study was 258,496 grains m-3, with an annual average of 51,699 ± 3,906 grains m-3 year-1. The primary source of pollen is Platanus orientalis, which produces 61.8% of the analyzed pollen. Grass pollen is the third primary component of the analyzed pollen, with a contribution of 5.82%. Among the weeds, the presence of Urticacea (3.74%) is remarkable. The pollination pattern of the trees is monophasic, and the grasses have a biphasic pattern. The trends indicate that the total pollen and tree pollen do not present a time trend that is statistically significant throughout the period of the study, whereas the grass pollen and weed pollen concentrations in the environment present a statistically significant decreasing trend. The cause of this decrease is unclear. The pollen load has doubled over the past decade. When the observed concentrations of the pollens were compared with the corresponding threshold levels, the results indicated that over the period of the study, the pollen concentrations were at moderate, high and very high levels for an average of 293 days per year. Systematic counts of the pollen grains are an essential method for diagnosing and treating patients with pollinosis and for developing forestation and urban planning strategies. PMID:25946339

  6. Trends and threshold exceedances analysis of airborne pollen concentrations in Metropolitan Santiago Chile.

    PubMed

    Toro A, Richard; Córdova J, Alicia; Canales, Mauricio; Morales S, Raul G E; Mardones P, Pedro; Leiva G, Manuel A

    2015-01-01

    Pollen is one of the primary causes of allergic rhinoconjunctivitis in urban centers. In the present study, the concentrations of 39 different pollens in the Santiago de Chile metropolitan area over the period 2009-2013 are characterized. The pollen was monitored daily using Burkard volumetric equipment. The contribution of each type of pollen and the corresponding time trends are evaluated. The concentrations of the pollens are compared with the established threshold levels for the protection of human health. The results show that the total amount of pollen grains originating from trees, grasses, weeds and indeterminate sources throughout the period of the study was 258,496 grains m-3, with an annual average of 51,699 ± 3,906 grains m-3 year-1. The primary source of pollen is Platanus orientalis, which produces 61.8% of the analyzed pollen. Grass pollen is the third primary component of the analyzed pollen, with a contribution of 5.82%. Among the weeds, the presence of Urticacea (3.74%) is remarkable. The pollination pattern of the trees is monophasic, and the grasses have a biphasic pattern. The trends indicate that the total pollen and tree pollen do not present a time trend that is statistically significant throughout the period of the study, whereas the grass pollen and weed pollen concentrations in the environment present a statistically significant decreasing trend. The cause of this decrease is unclear. The pollen load has doubled over the past decade. When the observed concentrations of the pollens were compared with the corresponding threshold levels, the results indicated that over the period of the study, the pollen concentrations were at moderate, high and very high levels for an average of 293 days per year. Systematic counts of the pollen grains are an essential method for diagnosing and treating patients with pollinosis and for developing forestation and urban planning strategies.

  7. Organic Nitrogen Concentrations and Trends in Urban Stormwater: Implications for Stormwater Monitoring and Management

    NASA Astrophysics Data System (ADS)

    Lusk, M. G.; Toor, G.

    2014-12-01

    Organic nitrogen (ON) can be a significant contributor of bioavailable N to the phytoplankton and bacteria that cause eutrophication and harmful algal blooms. In urban systems, urban stormwater runoff containing ON compounds is one source of potentially bioavailable N in water bodies. However, ON characterization and concentrations in urban stormwater are rarely reported or considered for urban stormwater management. We instrumented a 13-hectare residential catchment in Florida's Tampa Bay area with an ISCO autosampler and collected storm event runoff samples at 15-minute intervals during the 2013 wet season (June to September, n =236). Our objectives were to determine the (1) relative importance of ON compared to inorganic N forms (i.e., NO3- and NH4+) in the runoff, (2) investigate temporal trends in the ON concentrations in runoff, and (3) assess how rainfall depth and intensity affect any temporal trends. Mean concentration of total N in stormwater runoff for the wet season was 1.86 mg/l, of which dissolved and particulate ON were 63%. The dominance of ON in urban stormwater runoff suggests that the ON fraction should also be targeted when stormwater control measures call for N reductions. Particulate ON (PON) displayed a strong seasonal first flush trend as season progressed from June (1.45 mg/l; n =75) to September (0.20 mg/l; n = 28), while dissolved ON (DON) did not display any seasonal trend, with mean monthly concentrations ranging from 0.36 to 0.80 mg/l. A principal component analysis using storm event N concentrations, rainfall depth, and rainfall intensity as variables showed no significant correlation, suggesting that storms of various sizes and intensities can mobilize ON. The seasonal first flush observed for PON in the wet season can provide a window of time for optimal N removal and implies that stormwater best management practices should focus on capturing plant materials earlier in the season.

  8. Nutrient concentrations and loads in the northeastern United States - Status and trends, 1975-2003

    USGS Publications Warehouse

    Trench, Elaine C. Todd; Moore, Richard B.; Ahearn, Elizabeth A.; Mullaney, John R.; Hickman, R. Edward; Schwarz, Gregory E.

    2012-01-01

    The U.S. Geological Survey (USGS) National Water-Quality Assessment Program (NAWQA) began regional studies in 2003 to synthesize information on nutrient concentrations, trends, stream loads, and sources. In the northeastern United States, a study area that extends from Maine to central Virginia, nutrient data were evaluated for 130 USGS water-quality monitoring stations. Nutrient data were analyzed for trends in flow-adjusted concentrations, modeled instream (non-flow-adjusted) concentrations, and stream loads for 32 stations with 22 to 29 years of water-quality and daily mean streamflow record during 1975-2003 (termed the long-term period), and for 46 stations during 1993-2003 (termed the recent period), by using a coupled statistical model of streamflow and water quality developed by the USGS. Recent trends in flow-adjusted concentrations of one or more nutrients also were analyzed for 90 stations by using Tobit regression. Annual stream nutrient loads were estimated, and annual nutrient yields were calculated, for 47 stations for the long-term and recent periods, and for 37 additional stations that did not have a complete streamflow and water-quality record for 1993-2003. Nutrient yield information was incorporated for 9 drainage basins evaluated in a national NAWQA study, for a total of 93 stations evaluated for nutrient yields. Long-term downward trends in flow-adjusted concentrations of total nitrogen and total phosphorus (18 and 19 of 32 stations, respectively) indicate regional improvements in nutrient-related water-quality conditions. Most of the recent trends detected for total phosphorus were upward (17 of 83 stations), indicating possible reversals to the long-term improvements. Concentrations of nutrients in many streams persist at levels that are likely to affect aquatic habitat adversely and promote freshwater or coastal eutrophication. Recent trends for modeled instream concentrations, and modeled reference concentrations, were evaluated relative to

  9. Nation-wide trend in nitrate concentration of agricultural groundwater of Korea

    NASA Astrophysics Data System (ADS)

    Lim, J.; Kim, J.; Lee, S.; Lee, K.

    2013-12-01

    Nation-wide monitoring of groundwater in agricultural areas of Korea showed that about 27% of the total 3000 wells violate the groundwater standard of their relevant usage. Concerning nitrate concentration, 22% of the total wells are shown to exceed the relevant standard. The agricultural use of nitrates in organic and chemical fertilizers has been known as a major source of groundwater pollution. In the aim of protecting groundwater quality across the nation, this study analyzed the land use relationship with the nitrate concentration and the trend in water quality at each groundwater monitoring well. As the data had been collected from all over the nation, the characteristics of the data were needed to be scrutinized. With the analysis of variance (ANOVA), the data is tested for whether they are from the same population or not. Then, for the data from the same population, the Tobit regression model of multivariate analysis is applied in finding the relationship between the various types of land use and the nitrate concentration. For trend analysis of the water quality, nonparametric method of the Mann-Kendall test is applied. Both the seasonal characteristic and the total trend exclusive of the seasonal variation are analyzed. This study is expected to provide a sound basis in implementing effective actions for water quality protection in agricultural areas.

  10. Nutrient concentrations and loads in the northeastern United States - Status and trends, 1975-2003

    USGS Publications Warehouse

    Trench, Elaine C. Todd; Moore, Richard B.; Ahearn, Elizabeth A.; Mullaney, John R.; Hickman, R. Edward; Schwarz, Gregory E.

    2012-01-01

    The U.S. Geological Survey (USGS) National Water-Quality Assessment Program (NAWQA) began regional studies in 2003 to synthesize information on nutrient concentrations, trends, stream loads, and sources. In the northeastern United States, a study area that extends from Maine to central Virginia, nutrient data were evaluated for 130 USGS water-quality monitoring stations. Nutrient data were analyzed for trends in flow-adjusted concentrations, modeled instream (non-flow-adjusted) concentrations, and stream loads for 32 stations with 22 to 29 years of water-quality and daily mean streamflow record during 1975-2003 (termed the long-term period), and for 46 stations during 1993-2003 (termed the recent period), by using a coupled statistical model of streamflow and water quality developed by the USGS. Recent trends in flow-adjusted concentrations of one or more nutrients also were analyzed for 90 stations by using Tobit regression. Annual stream nutrient loads were estimated, and annual nutrient yields were calculated, for 47 stations for the long-term and recent periods, and for 37 additional stations that did not have a complete streamflow and water-quality record for 1993-2003. Nutrient yield information was incorporated for 9 drainage basins evaluated in a national NAWQA study, for a total of 93 stations evaluated for nutrient yields. Long-term downward trends in flow-adjusted concentrations of total nitrogen and total phosphorus (18 and 19 of 32 stations, respectively) indicate regional improvements in nutrient-related water-quality conditions. Most of the recent trends detected for total phosphorus were upward (17 of 83 stations), indicating possible reversals to the long-term improvements. Concentrations of nutrients in many streams persist at levels that are likely to affect aquatic habitat adversely and promote freshwater or coastal eutrophication. Recent trends for modeled instream concentrations, and modeled reference concentrations, were evaluated relative to

  11. Long term trends in PBDE concentrations in gannet (Morus bassanus) eggs from two UK colonies.

    PubMed

    Crosse, John D; Shore, Richard F; Jones, Kevin C; Pereira, M Glória

    2012-02-01

    We used the eggs of an avian sentinel, the Northern gannet (Morus bassanus), to determine long-term (1977-2007) trends in PBDE contamination in Western Atlantic (Ailsa Craig colony) and North Sea (Bass Rock colony) waters around the UK. BDEs 47, 49, 99, 100, 153, 154 were the most abundant and were found in all eggs. Individual congener and ΣPBDE concentrations in eggs from both colonies increased mainly from the late 1980s, peaked in 1994, and then rapidly declined so that concentrations in 2002 were similar to or lower than those in the 1970s and 1980s. The PBDE congener profile and temporal variation in PBDE concentrations suggests that the Penta-BDE technical formula was the main source of PBDE contamination. However, contributions of heavier BDE congeners to ΣPBDE concentrations have increased over time, suggesting other sources are becoming more important. PBDEs had no measurable effect on egg volume or eggshell index. PMID:22230073

  12. Trends in nitrate and dissolved-solids concentrations in ground water, Carson Valley, Douglas County, Nevada, 1985-2001

    USGS Publications Warehouse

    Rosen, Michael R.

    2003-01-01

    Analysis of trends in nitrate and total dissolved-solids concentrations over time in Carson Valley, Nevada, indicates that 56 percent of 27 monitoring wells that have long-term records of nitrate concentrations show increasing trends, 11 percent show decreasing trends, and 33 percent have not changed. Total dissolved-solids concentrations have increased in 52 percent of these wells and are stable in 48 percent. None of these wells show decreasing trends in total dissolved-solids concentrations. The wells showing increasing trends in nitrate and total dissolved-solids concentrations were always in areas that use septic waste-disposal systems. Therefore, the primary cause of these increases is likely the increase in septic-tank usage over the past 40 years.

  13. Temporal trends (1990-2000) in the concentration of cadmium, lead and mercury in mosses across Europe.

    PubMed

    Harmens, Harry; Norris, David A; Koerber, Georgia R; Buse, Alan; Steinnes, Eiliv; Rühling, Ake

    2008-01-01

    The European heavy metals in mosses survey provides data on the concentration of 10 heavy metals in naturally growing mosses. The survey has been repeated at five-yearly intervals and in this paper we report on the temporal trends in the concentration of cadmium, lead and mercury between 1990 and 2000. Metal- and country-specific temporal trends were observed. In general, the concentration of lead and cadmium in mosses decreased between 1990 and 2000; the decline was higher for lead than cadmium. For mercury not enough data were available to establish temporal trends between 1990 and 1995, but between 1995 and 2000 the mercury concentration in mosses did not change across Europe. The observed temporal trends for the concentrations in mosses were similar to the trends reported for the modelled total deposition of cadmium, lead and mercury in Europe.

  14. Long-Term Trends Worldwide in Ambient NO2 Concentrations Inferred from Satellite Observations

    PubMed Central

    Geddes, Jeffrey A.; Martin, Randall V.; Boys, Brian L.; van Donkelaar, Aaron

    2015-01-01

    Background Air pollution is associated with morbidity and premature mortality. Satellite remote sensing provides globally consistent decadal-scale observations of ambient nitrogen dioxide (NO2) pollution. Objective We determined global population-weighted annual mean NO2 concentrations from 1996 through 2012. Methods We used observations of NO2 tropospheric column densities from three satellite instruments in combination with chemical transport modeling to produce a global 17-year record of ground-level NO2 at 0.1° × 0.1° resolution. We calculated linear trends in population-weighted annual mean NO2 (PWMNO2) concentrations in different regions around the world. Results We found that PWMNO2 in high-income North America (Canada and the United States) decreased more steeply than in any other region, having declined at a rate of –4.7%/year [95% confidence interval (CI): –5.3, –4.1]. PWMNO2 decreased in western Europe at a rate of –2.5%/year (95% CI: –3.0, –2.1). The highest PWMNO2 occurred in high-income Asia Pacific (predominantly Japan and South Korea) in 1996, with a subsequent decrease of –2.1%/year (95% CI: –2.7, –1.5). In contrast, PWMNO2 almost tripled in East Asia (China, North Korea, and Taiwan) at a rate of 6.7%/year (95% CI: 6.0, 7.3). The satellite-derived estimates of trends in ground-level NO2 were consistent with regional trends inferred from data obtained from ground-station monitoring networks in North America (within 0.7%/year) and Europe (within 0.3%/year). Our rankings of regional average NO2 and long-term trends differed from the satellite-derived estimates of fine particulate matter reported elsewhere, demonstrating the utility of both indicators to describe changing pollutant mixtures. Conclusions Long-term trends in satellite-derived ambient NO2 provide new information about changing global exposure to ambient air pollution. Our estimates are publicly available at http://fizz.phys.dal.ca/~atmos/martin/?page_id=232. Citation

  15. Future trends in soil cadmium concentration under current cadmium fluxes to European agricultural soils.

    PubMed

    Six, L; Smolders, E

    2014-07-01

    The gradual increase of soil cadmium concentrations in European soils during the 20th century has prompted environmental legislation to limit soil cadmium (Cd) accumulation. Mass balances (input-output) reflecting the period 1980-1995 predicted larger Cd inputs via phosphate (P) fertilizers and atmospheric deposition than outputs via crop uptake and leaching. This study updates the Cd mass balance for the agricultural top soils of EU-27+Norway (EU-27+1). Over the past 15 years, the use of P fertilizers in the EU-27+1 has decreased by 40%. The current mean atmospheric deposition of Cd in EU is 0.35 g Cd ha(-1) yr(-1), this is strikingly smaller than values used in the previous EU mass balances (~3 g Cd ha(-1) yr(-1)). Leaching of Cd was estimated with most recent data of soil solution Cd concentrations in 151 soils, which cover the range of European soil properties. No significant time trends were found in the data of net applications of Cd via manure, compost, sludge and lime, all being small sources of Cd at a large scale. Modelling of the future long-term changes in soil Cd concentrations in agricultural top soils under cereal or potato culture predicts soil Cd concentrations to decrease by 15% over the next 100 years in an average scenario, with decreasing trends in some scenarios being more prevalent than increasing trends in other scenarios. These Cd balances have reverted from the general positive balances estimated 10 or more years ago. Uncertainty analysis suggests that leaching is the most uncertain relative to other fluxes.

  16. Trends in radionuclide concentrations in Hanford Reach fish, 1982 through 1992

    SciTech Connect

    Poston, T.M.

    1994-06-01

    Environmental monitoring has been conducted at the US Department of Energy`s Hanford Site in southeast Washington State since 1945. Fish from the Hanford Reach of the Columbia River, which borders the Site, are monitored annually. The two objectives of this report were (1) to evaluate trends in the concentrations of radionuclides [e.g., {sup 90}Sr and {sup 137}Cs] in two species of Columbia River fish [smallmouth bass and mountain whitefish] sampled from the Hanford Reach from 1982 through 1992; and (2) to determine the impact of Hanford Site releases on these two species and carp and fall chinook salmon collected during this time frame. The evaluation found gradual reductions of {sup 137}Cs in bass muscle and {sup 90}Sr in bass and whitefish carcass from 1982 through 1992. Concentrations of {sup 90}Sr in bass and whitefish followed the pattern established by reported Hanford Site releases from 1982 through 1992 and was supported by significant regression analyses comparing annual releases to sample concentration. Because data for carp have been collected only since 1990, the data base was inadequate for determining trends. Moreover, fall chinook salmon were only sampled once in this 11-year period. Concentrations of {sup 90}Sr and {sup 137}Cs in fish samples collected from distant background locations exceeded concentrations in Hanford Reach fish. Estimates of the dose from consumption of Hanford Reach fish were less than 0.001 times the National Council on Radiation Protection and Measurements and the US Department of Energy guideline of 100 mrem/yr.

  17. Pan-European modelling of riverine nutrient concentrations - spatial patterns, source detection, trend analyses, scenario modelling

    NASA Astrophysics Data System (ADS)

    Bartosova, Alena; Arheimer, Berit; Capell, Rene; Donnelly, Chantal; Strömqvist, Johan

    2016-04-01

    Nutrient transport models are important tools for large scale assessments of macro-nutrient fluxes (nitrogen, phosphorus) and thus can serve as support tool for environmental assessment and management. Results from model applications over large areas, i.e. from major river basin to continental scales can fill a gap where monitoring data is not available. Here, we present results from the pan-European rainfall-runoff and nutrient transfer model E-HYPE, which is based on open data sources. We investigate the ability of the E-HYPE model to replicate the spatial and temporal variations found in observed time-series of riverine N and P concentrations, and illustrate the model usefulness for nutrient source detection, trend analyses, and scenario modelling. The results show spatial patterns in N concentration in rivers across Europe which can be used to further our understanding of nutrient issues across the European continent. E-HYPE results show hot spots with highest concentrations of total nitrogen in Western Europe along the North Sea coast. Source apportionment was performed to rank sources of nutrient inflow from land to sea along the European coast. An integrated dynamic model as E-HYPE also allows us to investigate impacts of climate change and measure programs, which was illustrated in a couple of scenarios for the Baltic Sea. Comparing model results with observations shows large uncertainty in many of the data sets and the assumptions used in the model set-up, e.g. point source release estimates. However, evaluation of model performance at a number of measurement sites in Europe shows that mean N concentration levels are generally well simulated. P levels are less well predicted which is expected as the variability of P concentrations in both time and space is higher. Comparing model performance with model set-ups using local data for the Weaver River (UK) did not result in systematically better model performance which highlights the complexity of model

  18. Will the unexpected and unexplained trend towards declining nitrate concentrations in New Hampshire streams soon reverse?

    NASA Astrophysics Data System (ADS)

    Huntington, T. G.

    2005-05-01

    A recent report describes unexpected and unexplained declines in stream nitrate concentrations in forested watersheds of New Hampshire during recent decades. These declines are unexpected because continuing elevated atmospheric nitrogen (N) deposition is believed to exceed plant nutritional requirements which should result in increasing (rather than decreasing) stream nitrate concentrations. These declines are unexplained because several hypotheses have either been ruled out or remain untested. Increased rates of tree uptake are unlikely because region-wide assessments indicate stagnant or decreasing forest growth rates. Additionally, rates of atmospheric N deposition have remained fairly constant in recent years. Forest maturation has also been rejected as a potential explanation. Increasing tree N uptake during forest recovery from disturbances like insect defoliations and severe drought were provisionally ruled out because they do not explain the regional nature of the decline. Atmospheric CO2 fertilization effects are thought to be too small, and have not been detected as increases in aboveground growth. Interannual climatic variability, including soil frost dynamics, could explain part of the declines, but these hypotheses remain untested. Regional trends towards warmer, wetter, and longer growing seasons are consistent with increasing N uptake, but there is no evidence for a corresponding increase in forest growth. Nitrogen sequestration in soil organic matter could explain the observed nitrate decline, and may have increased in recent years through stimulation of belowground carbon cycling due to CO2 fertilization. In addition, climate changes have favored an intensification of belowground N cycling that could lead to a narrowing of the C:N ratio and increased N sequestration. If increasing atmospheric CO2 and a warmer and wetter climate are at least partially responsible for increasing N sequestration, it is not likely that the current trends in stream

  19. Long-Term Trends in DOC Concentrations and Fluxes in a Southern Appalachian Headwater Stream

    NASA Astrophysics Data System (ADS)

    Singh, N.; Bernhardt, E. S.; Reyes, W. M.; Bhattacharya, R.; Meyer, J. L.; Knoepp, J. D.; Emanuel, R. E.

    2014-12-01

    Dramatic increases in dissolved organic carbon (DOC) of stream water have been reported for aquatic ecosystems of the Northern Hemisphere and have been attributed variously to global warming, recovery from acid rain, or to altered hydrologic connections between watersheds and receiving streams. Here, we analyzed one of the longest continuous records of stream water DOC available in the Southeastern US. The record comes from a forested headwater stream at Coweeta Hydrologic Laboratory in the Southern Appalachians (NC, USA). In contrast to the increasing DOC trends reported for northern temperate watersheds, we observed steep declines in both the volume-weighted concentrations of stream DOC (43% decline) and DOC fluxes (55% decline) between 1988 and 2005. Annual mean runoff declined by 38%, which we attributed mainly to a 47% decline in baseflow during the study period. Increased soil [SO42-] and ionic strength of soil water indicate that soils within the watershed are becoming more acidic through time. Together, these results suggest that the dramatic decline in DOC concentrations can be attributed to: 1) a decline in runoff, which affected the mobilization of DOC from uplands to the stream, and 2) gradual soil acidification, which probably restricted the formation of DOC within the watershed. Declining DOC in headwater streams has implications not only for carbon and other nutrient cycles but also for the health of aquatic habitats throughout this region. More broadly, these results emphasize that long-term trends in DOC may differ for streams across the Northern Hemisphere. Long-term datasets have the potential to reveal the range of these trends and the underlying processes that drive them.

  20. Statement of the Authors Guild on "The Continuing Trend To Concentration of Power in the Book Publishing Industry."

    ERIC Educational Resources Information Center

    Authors Guild, Inc., New York, NY.

    This is one of several papers presented at a Federal Trade Commission Symposium on Media Concentration. A statement by the Authors Guild, it examines the merger-takeover trend in book publishing. The Authors Guild feels that the merger trend in book publishing has passed beyond the warning line drawn by the antimerger clause of the Clayton Act,…

  1. Historical trends and concentrations of fecal coliform bacteria in the Brandywine Creek basin, Chester County, Pennsylvania

    USGS Publications Warehouse

    Town, D.A.

    2001-01-01

    The Brandywine Creek in Chester County is used for recreation and as an important source of drinking water. For this study, 40 sites were established for collection of water samples for analysis of fecal coliform and Escherichia coli bacteria in 1998-99. Samples were collected during base-flow conditions and during five storms in which rainfall exceeded 0.5 inch. During base- flow conditions, the median concentrations of fecal coliform bacteria exceeded 200 col/100 mL at 26 of the 40 sites (65 percent). During stormflow conditions, the median concentration of fecal coliform bacteria exceeded the Pennsylvania Department of Environmental Protection (PaDEP) criterion of 200 col/100 mL at 30 of 33 sites sampled (91 percent). Trends in fecal coliform bacteria concentrations were downward for the period 1973-99 at three long-term water-quality monitor stations, the result of upgrades in wastewater treatment plants, decreases in point-source discharges, and a decrease in agricultural land. A positive relation exists between streamflow and concentrations of fecal coliform bacteria at two of the long-term stations, but concentrations are elevated in base flow and stormflow at all three stations. Factors affecting bacteria concentrations in the Brandywine Creek Basin include nonpoint-source contaminants, reservoirs, seasonality, and stormflow. Nonpoint sources of bacterial contamination in the basin include, but are not limited to, land-surface runoff, urbanization, agricultural processes, groundwater contamination, and wildlife. Bacteria concentrations in streams that flow directly from the reservoirs are much lower than the concentrations in the streams flowing into the reservoirs. During March, April, May, October, and November, the Brandywine Creek tends to have lower water temperatures and bacteria concentrations than during June, July, August, and September. The 10-year median concentrations of bacteria at West Branch Brandywine Creek at Modena and East Branch

  2. Temporal and spatial trends in freshwater fish tissue mercury concentrations associated with mercury emissions reductions.

    PubMed

    Hutcheson, Michael S; Smith, C Mark; Rose, Jane; Batdorf, Carol; Pancorbo, Oscar; West, Carol Rowan; Strube, Joseph; Francis, Corey

    2014-02-18

    Mercury (Hg) concentrations were monitored from 1999 to 2011 in largemouth bass (LMB) and yellow perch (YP) in 23 lakes in Massachusetts USA during a period of significant local and regional Hg emissions reductions. Average LMB tissue Hg concentration decreases of 44% were seen in 13 of 16 lakes in a regional Hg "hotspot" area. YP in all lakes sampled in this area decreased 43% after the major emissions reductions. Comparative decreases throughout the remainder of the state were 13% and 19% for LMB and YP respectively. Annual tissue mercury concentration rate decreases were 0.029 (LMB) and 0.016 mg Hg/kg/yr (YP) in the hotspot. In lakes around the rest of the state, LMB showed no trend and YP Hg decreased 0.0068 mg Hg/kg/yr. Mercury emissions from major point sources in the hotspot area decreased 98%, and 93% in the rest of the state from the early 1990s to 2008. The significant declines in fish Hg concentrations in many lakes occurred over the second half of a two decade decrease in Hg emissions primarily from municipal solid waste combustors and, secondarily, from other combustion point sources. In addition to the substantial Hg emissions reductions achieved in Massachusetts, further regional, national and global emissions reductions are needed for fish Hg levels to decrease below fish consumption advisory levels. PMID:24494622

  3. Concentrations and trends of Perfluorinated chemicals in potential indoor sources from 2007 through 2011 in the US

    EPA Science Inventory

    Certain perfluorinated chemicals in consumer products have been associated with developmental toxicity and other adverse health effects. Temporal trends in the concentrations of selected perfluorinated chemicals (PFCs), including perfluorooctanoic acid (PFOA) and other perfluoroc...

  4. Temporal and geographic trends in trace element concentrations in moose from Yukon, Canada.

    PubMed

    Gamberg, Mary; Palmer, Mark; Roach, Patrick

    2005-12-01

    The Yukon Contaminants Committee has conducted a hunter survey since 1994, annually requesting tissue samples from successful moose hunters in the Yukon. Moose kidney, liver and muscle tissue were analyzed for arsenic, cadmium, chromium, cobalt, copper, lead, mercury, molybdenum, selenium and zinc. Levels of most trace elements measured were not of concern toxicologically or in terms of deficiencies. Although hepatic selenium concentrations in Yukon moose were high compared to moose from other locations, and to domestic cattle, no indications of selenium toxicity have been observed. Renal and hepatic concentrations of cadmium in Yukon moose were also high when compared with moose from other locations. Results from this study suggest that 1) some moose in this area may be suffering from sublethal effects of Cd toxicity, 2) moose in this area may have evolved a high level of natural cadmium tolerance, 3) moose in this area may have developed a high level of cadmium tolerance over their lifetimes, or 4) moose, as a species, have a high level of Cd tolerance. Health Canada has recommended limiting consumption of Yukon moose kidneys and livers to one/year/person. Cadmium concentrations were positively correlated with age in moose kidneys, while arsenic, copper, molybdenum and selenium showed a negative correlation. Renal chromium and zinc showed an increasing trend from 1994-2001, while copper showed a decreasing trend, although in all three cases the r-values and the changes over time were low. None of the other elements tested exhibited a significant change over time. Analysis of moose renal element concentrations with stream sediment element concentrations was carried out on an ecoregion basis, a game management zone basis and a moose home range basis. Results suggest that, at least to some degree, renal element concentrations in moose are affected by the geology of their environment, particularly for cadmium, arsenic and lead. The results of these analyses are

  5. Trends in selected ambient volatile organic compound (VOC) concentrations and a comparison to mobile source emission trends in California's South Coast Air Basin

    NASA Astrophysics Data System (ADS)

    Pang, Yanbo; Fuentes, Mark; Rieger, Paul

    2015-12-01

    Trends in ambient concentrations of Volatile Organic Compounds (VOC) in the South Coast Air Basin (SoCAB) are compared to trends in VOC emissions from Light-Duty Gasoline Vehicles (LDGV) tested on chassis dynamometers and to trends observed in tunnel studies during the same period to understand the impacts of gasoline vehicle emissions on ambient VOC concentrations from 1999 to 2009. Annual median concentrations for most ambient VOCs decreased 40% from 1999 to 2009 in the SoCAB, based on data from the Photochemical Assessment Monitoring Stations (PAMS). Annual concentration decreases of most compounds, except 2,2,4-trimethylpentane, are highly correlated with the decrease of acetylene, a marker for tailpipe emissions from LDGV. This indicates that ambient VOC concentration decreases were likely due to tailpipe emission reductions from gasoline vehicles. Air Toxics Monitoring Network data also support this conclusion. Benzene concentration-normalized ratios for most compounds except ethane, propane, isoprene, and 2,2,4-trimethylpentane were stable even as these compound concentrations decreased significantly from 1999 to 2009. Such stability suggests that the main sources of ambient VOC were still the same from 1999 to 2009. The comparison of trends in dynamometer testing and tunnel studies also shows that tailpipe emissions remained the dominant source of tunnel LDGV emissions. The pronounced changes in 2,2,4-trimethylpentane ratios due to the introduction of Phase 3 gasoline also confirm the substantial impact of LDGV emissions on ambient VOCs. Diurnal ambient VOC data also suggest that LDGV tailpipe emissions remained the dominant source of ambient VOCs in the SoCAB in 2009. Our conclusion, which is that current inventory models underestimate VOC emissions from mobile sources, is consistent with that of several recent studies of ambient trends in the SoCAB. Our study showed that tailpipe emissions remained a bigger contributor to ambient VOCs than evaporative

  6. Trends in serum cotinine concentrations among daily cigarette smokers: data from NHANES 1999-2010.

    PubMed

    Jain, Ram B

    2014-02-15

    To the best of our knowledge, there have been no apparent studies of the trends in serum cotinine levels among smokers. Data from National Health and Nutrition Examination Survey for the period 1999-2010 were used to evaluate trends for serum cotinine levels; average number of cigarettes smoked per day; and Cambridge filter method (CFM) tar and CFM nicotine levels by gender, race/ethnicity, and cigarette mentholation status. Regression models were fitted to evaluate the factors associated with serum cotinine levels. Serum cotinine levels increased over time for both males and females, non-Hispanic whites and others. CFM nicotine levels also rose over time for cigarettes smoked by both males and females and by both non-Hispanic whites and non-Hispanic blacks. Average number of cigarettes smoked per day decreased over time for females, non-Hispanic whites and non-Hispanic blacks. CFM tar levels fell only for Mexican Americans. Exposure to second hand smoke at home was found to be associated with more than 1 ng/ml increase in serum cotinine levels. This large study on a nationally representative sample of daily smokers suggested that increasing concentrations of CFM nicotine in cigarettes over time led to elevated serum cotinine levels even though the number of cigarettes smoked daily remained relatively constant. PMID:24291557

  7. Temporal evolution of organic carbon concentrations in Swiss lakes: trends of allochthonous and autochthonous organic carbon.

    PubMed

    Rodríguez-Murillo, J C; Filella, M

    2015-07-01

    Evaluation of time series of organic carbon (OC) concentrations in lakes is useful for monitoring some of the effects of global change on lakes and their catchments. Isolating the evolution of autochthonous and allochthonous lake OC might be a useful way to differentiate between drivers of soil and photosynthetic OC related changes. However, there are no temporal series for autochthonous and allochthonous lake OC. In this study, a new approach has been developed to construct time series of these two categories of OC from existing dissolved organic carbon (DOC) data. First, temporal series (longer than ten years) of OC have been compiled for seven big Swiss lakes and another 27 smaller ones and evaluated by using appropriate non-parametric statistical methods. Subsequently, the new approach has been applied to construct time series of autochthonous and allochthonous lake OC in the seven big lakes. Doing this was possible because long term series of DOC concentrations at different depths are available for these lakes. Organic carbon concentrations generally increase in big lakes and decrease in smaller ones, although only in some cases are these trends statistically significant. The magnitude of the observed changes is generally small in big lakes (<1% annual change) and larger in smaller lakes. Autochthonous DOC concentrations in big lakes increase or decrease depending on the lake and the station but allochthonous DOC concentrations generally increase. This pattern is consistent with an increase in the OC input from the lakes' catchments and/or an increase in the refractoriness of the OC in question, and with a temporal evolution of autochthonous DOC depending on the degree of recovery from past eutrophication of each particular lake. In small lakes, OC dynamics are mainly driven by decreasing biological productivity, which in many, but not all cases, outweighs the probable increase of allochthonous OC.

  8. Trends in suspended-sediment loads and concentrations in the Mississippi River Basin, 1950–2009

    USGS Publications Warehouse

    Heimann, David C.; Sprague, Lori A.; Blevins, Dale W.

    2011-01-01

    Trends in loads and concentrations of suspended sediment and suspended sand generally were downward for stations within the Mississippi River Basin during the 60-, 34-, and 12-year periods analyzed. Sediment transport in the lower Mississippi River has historically been, and continues to be, most closely correlative to sediment contributions from the Missouri River, which generally carried the largest annual suspended-sediment load of the major Mississippi River subbasins. The closure of Fort Randall Dam in the upper Missouri River in 1952 was the single largest event in the recorded historical decline of suspended-sediment loads in the Mississippi River Basin. Impoundments on tributaries and sediment reductions as a result of implementation of agricultural conservation practices throughout the basin likely account for much of the remaining Mississippi River sediment transport decline. Scour of the main-stem channel downstream from the upper Missouri River impoundments is likely the largest source of suspended sand in the lower Missouri River. The Ohio River was second to the Missouri River in terms of sediment contributions, followed by the upper Mississippi and Arkansas Rivers. Declines in sediment loads and concentrations continued through the most recent analysis period (1998–2009) at available Mississippi River Basin stations. Analyses of flow-adjusted concentrations of suspended sediment indicate the recent downward temporal changes generally can be explained by corresponding decreases in streamflows.

  9. Regional Variation and Trends in IASI-Observed Atmospheric Ammonia Concentrations over the United States

    NASA Astrophysics Data System (ADS)

    Schiferl, L. D.; Heald, C. L.; Van Damme, M.; Clerbaux, C.; Coheur, P.

    2013-12-01

    Quantifying atmospheric ammonia is a critical first step in investigating its role in the formation of fine particulate matter and ecosystem change. This study uses five years (2008-2012) of a new measurement of ammonia column concentrations derived from the Infrared Atmospheric Sounding Interferometer (IASI) instrument to explore ammonia levels in several regions (e.g. the Midwest, California, the Southeast) of the United States. These satellite measurements offer extensive daily coverage, providing a constraint on the evolution and spatial variation of ammonia across the United States. We identify observed ammonia variation between the regions in terms of both intra-annual (seasonal) change and trends throughout the entire time period. These variations are related to factors controlling ammonia emissions, chemistry and deposition, such as human and animal populations, farming practices, land use change and meteorological variables. These variations can also be used to drive Earth system model simulations of ammonia's effects on air quality, radiation balance and environmental degradation.

  10. Seasonal trends of dry and bulk concentration of nitrogen compounds over a rain forest in Ghana

    NASA Astrophysics Data System (ADS)

    Fattore, F.; Bertolini, T.; Materia, S.; Gualdi, S.; Thongo M'Bou, A.; Nicolini, G.; Valentini, R.; De Grandcourt, A.; Tedesco, D.; Castaldi, S.

    2014-06-01

    African tropical forests of the equatorial belt might receive significant input of extra nitrogen derived from biomass burning occurring in the north savanna belt and transported equatorward by northeastern winds. In order to test this hypothesis an experiment was set up in a tropical rain forest in the Ankasa Game Reserve and Nini-Suhien National Park (Ghana) aimed at quantifying magnitude and seasonal variability of concentrations of N compounds, present as gas and aerosol (dry nitrogen) or in the rainfall (bulk nitrogen), over the studied forest; and relating their seasonal variability to trends of local and regional winds and rainfall and to variations of fire events in the region. Three DELTA systems, implemented for monthly measurements of NO2, were mounted over a tower at 45 m height, 20 m above forest canopy to sample gas (NH3, NO2, HNO3, HCl, SO2) and aerosol (NH4+, NO3-, and several ions), together with three tanks for bulk rainfall collection (to analyze NH4+, NO3- and ion concentration). The tower was provided with a sonic anemometer to estimate local wind data. The experiment started in October 2011 and data up to October 2012 are presented. To interpret the observed seasonal trends of measured compounds, local and regional meteo data and regional satellite fire data were analyzed. The concentration of N compounds significantly increased from December to April, during the drier period, peaking from December to February when NE winds (the Harmattan) were moving dry air masses over the west-central African region, and the Intertropical Convergence Zone (ITCZ) was at its minimum latitude over the Equator. This period also coincided with fire peaks in the whole region. On the contrary, N concentration in gas, aerosol and rain decreased from May to October when prevalent winds arrived from the sea (southeast), during the monsoon period. Both ionic compositions of rain and analysis of local wind direction showed a significant and continuous presence of see

  11. Museum Preserved Bivalves as Indicators of Long-term Trends in Methylmercury Concentrations

    NASA Astrophysics Data System (ADS)

    Luengen, A. C.; Foslund, H. M.; Greenfield, B. K.

    2015-12-01

    Despite the many efforts to reduce mercury concentrations in the environment, there are relatively few datasets on long-term trends in mercury in biota, especially for the bioavailable form, methylmercury (MeHg). This study used museum preserved bivalves (stored in ethanol) to look at MeHg trends in the Asian date mussel Musculista senhousia and the Asian clam Potamocorbula amurensis, collected from San Francisco Bay, California between 1975 and 2012. For each sampling date, 4 to 15 individuals were obtained from museum collections (N = 156 total specimens), freeze-dried, weighed, homogenized, digested, and individually analyzed for MeHg using trace metal clean techniques. The bivalves were also analyzed for δ13C and δ15N to look for changes in food web structure. P. amurensis specimens were only available from 1988 to 2012, and an increase in MeHg was observed during that time. In contrast, M. senhousia specimens were available for the entire 37 year period and exhibited a significant decline in MeHg in the southern reach of the estuary (South Bay). The median MeHg concentration in M. senhousia was highest at 239 ng/g dw in October 1975. That year was the last year of operations for the New Almaden Mercury Mining District, which drained into South Bay. By the 1990s, MeHg concentrations in M. senhousia dropped significantly to a median of 37 ng/g dw. Isotopic δ15N values did not support a hypothesis of reduced trophic position causing the MeHg decline. Over the study duration, δ15N increased in M. senhousia, which we attributed to a baseline shift. We also observed a decline in δ13C since 2000, which may represent a shift in bivalve carbon towards greater utilization of planktonic sources. To validate the use of museum specimens, we ran a preservation study, where we collected fresh bivalves, fixed them in ethanol or formalin, and then transferred them to ethanol for long-term storage. Although MeHg concentrations increased after 1 week, they stabilized over

  12. Bi-phasic trends in mercury concentrations in blood of Wisconsin common loons during 1992–2010

    USGS Publications Warehouse

    Meyer, Michael W.; Rasmussen, Paul W.; Watras, Carl J.; Fevold, Brick M.; Kenow, Kevin P.

    2011-01-01

    Wisconsin Department of Natural Resources (WDNR) assessed the ecological risk of mercury (Hg) in aquatic systems by monitoring common loon (Gavia immer) population dynamics and blood Hg concentrations. We report temporal trends in blood Hg concentrations based on 334 samples collected from adults recaptured in subsequent years (resampled 2-9 times) and from 421 blood samples of chicks collected at lakes resampled 2-8 times 1992-2010.. Temporal trends were identified with generalized additive mixed effects models (GAMMs) and mixed effects models to account for the potential lack of independence among observations from the same loon or same lake. Trend analyses indicated that Hg concentrations in the blood of Wisconsin loons declined over the period 1992-2000, and increased during 2002-2010, but not to the level observed in the early 1990s. The best fitting linear mixed effects model included separate trends for the two time periods. The estimated trend in Hg concentration among the adult loon population during 1992-2000 was -2.6% per year and the estimated trend during 2002-2010 was +1.8% per year; chick blood Hg concentrations decreased by -6.5% per year during 1992-2000, but increased 1.8% per year during 2002-2010. This bi-phasic pattern is similar to trends observed for concentrations of methylmercury (meHg) and SO4 in lake water of a well studied seepage lake (Little Rock Lake, Vilas County) within our study area. A cause-effect relationship between these independent trends is hypothesized.

  13. Indoor Radon and Its Decay Products: Concentrations, Causes, and Control Strategies

    SciTech Connect

    Nero, A.V.; Gadgil, A.J.; Nazaroff, W.W.; Revzan, K.L.

    1990-01-01

    This report is an introduction to the behavior of radon 222 and its decay products in indoor air. This includes review of basic characteristics of radon and its decay products and of features of the indoor environment itself, all of which factors affect behavior in indoor air. The experimental and theoretical evidence on behavior of radon and its decay products is examined, providing a basis for understanding the influence of geological, structural, and meteorological factors on indoor concentrations, as well as the effectiveness of control techniques. We go on to examine three important issues concerning indoor radon. We thus include (1) an appraisal of the concentration distribution in homes, (2) an examination of the utility and limitations of popular monitoring techniques and protocols, and (3) an assessment of the key elements of strategies for controlling radon levels in homes.

  14. Spatial and monthly trends in speciated fine particle concentration in the United States

    NASA Astrophysics Data System (ADS)

    Malm, William C.; Schichtel, Bret A.; Pitchford, Marc L.; Ashbaugh, Lowell L.; Eldred, Robert A.

    2004-02-01

    In the spring of 1985 an interagency consortium of federal land management agencies and the Environmental Protection Agency established the Interagency Monitoring of Protected Visual Environments (IMPROVE) network to assess visibility and aerosol monitoring for the purpose of tracking spatial and temporal trends of visibility and visibility-impairing particles in rural areas. The program was initiated with 20 monitoring sites and was expanded to 165 sites between 2000 and 2003. This paper reports on fine aerosol data collected in the year 2001 at 143 sites. The major fine (dp < 2.5 μm) particle aerosol species, sulfates, nitrates, organics, light-absorbing carbon, and wind-blown dust, and coarse gravimetric mass are monitored, and at some sites, light scattering and/or extinction are measured. Sulfates, carbon, and crustal material are responsible for most of the fine mass at the majority of locations throughout the United States, while at sites in southern California and the midwestern United States, nitrates can contribute significantly. In the eastern United States, sulfates contribute between 50 and 60% of the fine mass. Sulfate concentrations tend to be highest in the summer months while organic concentrations can be high in the spring, summer, or fall seasons, depending upon fire-related emissions. However, at the two urban sites, Phoenix, Arizona, and Puget Sound, Washington, organics peak during the winter months. Nitrate concentrations also tend to be highest during the winter months. During the spring months in many areas of the western United States, fine soil can contribute as much as 40% of fine mass. The temporal changes in soil concentration that occur simultaneously over much of the western United States including the Rocky Mountain region suggest a large source region, possibly long-range transport of Asian dust.

  15. Evaluating regional trends in ground-water nitrate concentrations of the Columbia Basin ground water management area, Washington

    USGS Publications Warehouse

    Frans, Lonna M.; Helsel, Dennis R.

    2005-01-01

    Trends in nitrate concentrations in water from 474 wells in 17 subregions in the Columbia Basin Ground Water Management Area (GWMA) in three counties in eastern Washington were evaluated using a variety of statistical techniques, including the Friedman test and the Kendall test. The Kendall test was modified from its typical 'seasonal' version into a 'regional' version by using well locations in place of seasons. No statistically significant trends in nitrate concentrations were identified in samples from wells in the GWMA, the three counties, or the 17 subregions from 1998 to 2002 when all data were included in the analysis. For wells in which nitrate concentrations were greater than 10 milligrams per liter (mg/L), however, a significant downward trend of -0.4 mg/L per year was observed between 1998 and 2002 for the GWMA as a whole, as well as for Adams County (-0.35 mg/L per year) and for Franklin County (-0.46 mg/L per year). Trend analysis for a smaller but longer-term 51-well dataset in Franklin County found a statistically significant upward trend in nitrate concentrations of 0.1 mg/L per year between 1986 and 2003. The largest increase of nitrate concentrations occurred between 1986 and 1991. No statistically significant differences were observed in this dataset between 1998 and 2003 indicating that the increase in nitrate concentrations has leveled off.

  16. Satellite-Based Spatiotemporal Trends in PM2.5 Concentrations: China, 2004–2013

    PubMed Central

    Ma, Zongwei; Hu, Xuefei; Sayer, Andrew M.; Levy, Robert; Zhang, Qiang; Xue, Yingang; Tong, Shilu; Bi, Jun; Huang, Lei; Liu, Yang

    2015-01-01

    L, Liu Y. 2016. Satellite-based spatiotemporal trends in PM2.5 concentrations: China, 2004–2013. Environ Health Perspect 124:184–192; http://dx.doi.org/10.1289/ehp.1409481 PMID:26220256

  17. Trends In Concentrations And Loads Of Nitrogen And Carbon In Streams And Rivers Of The Western United States, 1990-Present

    NASA Astrophysics Data System (ADS)

    Miller, M.; Wiele, S. M.; Brasher, A.

    2010-12-01

    Nutrients, including nitrogen and carbon, are essential for the growth and survival of organisms in aquatic ecosystems. However, high concentrations of these nutrients can negatively impact natural ecosystems and human health through processes such as eutrophication of streams and lakes, and the production of toxic disinfection byproducts in drinking water. We compiled data on total nitrogen (TN) and dissolved organic carbon (DOC) concentrations measured from 1990-2010 in 40 streams and rivers across the Western United States, as part of the United States Geological Survey (USGS) National Water Quality Assessment (NAWQA) Program. These data were used to calculate site-specific trends over time in TN and DOC concentrations (resulting from natural and human factors), flow-adjusted concentrations (trends resulting from watershed conditions upstream of a site), and loads (trends in mass transported downstream). Flow-adjusted concentrations and loads were calculated using the USGS load estimator (LOADEST) program, and trends in concentrations and loads over time were investigated using the estimate trend (ESTREND) program. To define site groupings, a principal component analysis (PCA) was run on environmental variables, including precipitation, temperature, land use, population density, and nutrient inputs from fertilizer application, manure application, and atmospheric deposition. The direction and magnitude of trends in concentration and load varied depending on the group in which a given site was categorized. Our results suggest that environmental conditions such as climate and anthropogenic activities in a watershed (as characterized by land use and population density) both effect concentrations and loads of nitrogen and carbon in streams, and ultimately ecosystem health in streams and rivers of the Western United States. These results provide information that can be used by managers to effectively plan for the potential future response of aquatic ecosystems to

  18. Assessing trends in organochlorine concentrations in Lake Winnipeg fish following the 1997 red river flood

    USGS Publications Warehouse

    Stewart, A.R.; Stern, G.A.; Lockhart, W.L.; Kidd, K.A.; Salki, A.G.; Stainton, M.P.; Koczanski, K.; Rosenberg, G.B.; Savoie, D.A.; Billeck, B.N.; Wilkinson, Philip M.; Muir, D.C.G.

    2003-01-01

    As we move toward the virtual elimination of persistent organic pollutants (POPs) in the environment our understanding of how short-term variability affects long-term trends of POPs in natural populations will become increasingly more important. In this study we report short-term trends in organochlorine (OC) levels in fish from Lake Winnipeg in the months and years following the 1997 100-year flood of the Red River ecosystem. Our goal was to understand the effects of an episodic event on OC levels in benthic and pelagic invertebrates and in fish. Despite elevated loading of OCs into the south basin of Lake Winnipeg during the flood there were no differences in OC levels of surface sediments or emergent mayflies. After adjusting for differences in lipid content and length among sample times, we did find significant increases in total DDT (??DDT) and total polychlorinated biphenyl (??PCB) post-flood (March 1999) in top predators including walleye and burbot. Significant increases were also observed in OC concentrations of zooplankton and yellow perch (> 2 fold in ??PCB, ??DDT, total chlordane (??CHL), total chlorobenzenes (??CBZ)) and walleye (1.4 fold ??PCB) over a 2-month period in the summer following the flood. Analysis of specific congener patterns over time suggest that the major changes in fish OC levels pre- and post-flood did not appear to be linked to transport of new compounds into the Lake during the flood, but to species shifts within the plankton community. Our results indicate that short-term variation (???2 months) in OC distributions within biota may be equal to or greater than those resulting from episodic events such as spring floods.

  19. African dust outbreaks over the Mediterranean Basin during 2001-2011: concentrations, phenomenology and trends

    NASA Astrophysics Data System (ADS)

    Pey, Jorge; Querol, Xavier; Alastuey, Andres; Forastiere, Franceso; Stafoggia, Massimo

    2013-04-01

    Concentrations, phenomenology and trends of African dust outbreaks over the whole Mediterranean Basin werestudied on an 11-year period (2001-2011). This work has been performed in the context of the MED-PARTICLES (LIFE programme, EU) project, devoted to quantify short-term health effects of particulate matter over the Mediterranean region by distinguishing different particle sizes, chemical components and sources, with emphasis in the effects of African dust. In order to evaluate conduct this investigation, PM10 data from 19 regional and suburban background sites West to East in the Mediterranean area were compiled. After identifying the daily occurrence of African dust outbreaks, a methodology for estimating natural dust contributions on daily PM10 concentrations was applied. Our findings point out that African dust outbreaks are sensibly more frequent in southern sitesacross the Mediterranean, from 30 to 37 % of the annual days, whereas they occur less than 20% of the annual days in northern sites. The central Mediterranean emerges as a transitional area, with slightly higher frequency of dust episodes in its lower extreme when compared to similar latitudinal positions in western and eastern sides of the Basin. A decreasing south to north gradient of African dust contribution to PM10, driven by the latitudinal position of the monitoring sites at least 25°E westwards across the Basin,is patent across the Mediterranean. From 25°E eastwards, higher annual dust contributions are encountered due to the elevated annual occurrence of severe episodesof dust but also because of inputs from Middle Eastern deserts. Concerning seasonality patterns and intensity characteristics, a clear summer prevalence is observed in the western part, with low occurrence of severe episodes (daily dust averages over 100 µg m-3 in PM10); no seasonal trend is detected in the central region, with moderate-intensity episodes; and significantly higher contributions are common in autumn

  20. Monitoring spatiotemporal variations of diel radon concentrations in peatland and forest ecosystems based on neural network and regression models.

    PubMed

    Evrendilek, Fatih; Denizli, Haluk; Yetis, Hakan; Karakaya, Nusret

    2013-07-01

    Concentrations of outdoor radon-222 ((222)Rn) in temperate grazed peatland and deciduous forest in northwestern Turkey were measured, compared, and modeled using artificial neural networks (ANNs) and multiple nonlinear regression (MNLR) models. The best-performing multilayer perceptron model selected out of 28 ANNs considerably enhanced accuracy metrics in emulating (222)Rn concentrations relative to the MNLR model. The two ecosystems had similar diel patterns with the lowest (222)Rn concentrations in the afternoon and the highest ones near dawn. Mean level (5.1 + 2.5 Bq m(-3) h(-1)) of (222)Rn in the forest was three times smaller than that (15.8 + 9.7 Bq m(-3)) of (222)Rn in the peatland. Mean (222)Rn level had negative and positive relationships with air temperature and relative humidity, respectively.

  1. The mathematical model of radon-222 accumulation in underground mines

    NASA Astrophysics Data System (ADS)

    Klimshin, A.

    2012-04-01

    Necessity to control underground mine air radon level arises during building and operating mines as well as auto and railway tunnels including those for metros. Calculation of underground mine air radon level can be fulfilled for estimation of potential radon danger of area for underground structure building. In this work the new mathematical model of radon accumulation in underground mines has been suggested. It takes into consideration underground mine dimensions, air exchange factor and soils ability to emanate radon. The following assumptions have been taken for model development. It is assumed that underground mine is a cylinder of length L and of base area S. Due to ventilation atmosphere air of volume activity Catm, is coming in through one cylinder base and is going out of volume activity Cind from underground mine. Diffusion radon flux is coming in through side surfaces of underground mine. The sources of this flux are radium-226 atoms distributed evenly in rock. For simplification of the task it considered possible to disregard radon emanation by loosened rock and underground waters. As a result of solution of the radon diffusion equation the following expression for calculation of radon volume activity in underground space air has been got: 2·r0 ·λv ·Catm-·l·K0(r0/l)-+D-·K1(r0/l)·C0- Cind = 2·(λ+ λv)·r0 ·l·K0 (r0/l)+ D ·K1(r0/l) . The following designations are used in this expression: Kν(r) - the second genus modified Bessel's function, C0 - equilibrium radon volume activity in soil air, l - diffusion radon length in soil, D - radon diffusion factor, r0 - radius of underground tunnel, λv - factor of air exchange. Expression found may be used for calculation of the minimum factor of necessary air exchange for ensuring safe radon levels in underground spaces. With this worked out model expected levels of radon volume activity were calculated for air in the second metro line underground spaces in the city of Yekaterinburg, Russia.

  2. Potential Radon-222 Emissions from the Thorium Nitrate Stockpile

    SciTech Connect

    Terry, J.W.

    2003-09-04

    The Defense National Stockpile Center (DNSC), a field level activity of the Defense Logistics Agency, has stewardship of a stockpile of thorium nitrate that has been in storage for decades. The thorium nitrate stockpile was produced from 1959 to 1964 for the Atomic Energy Commission and previously has been under the control of several federal agencies. The stockpile consists of approximately 7 million pounds of thorium nitrate crystals (hydrate form) stored at two depot locations in the United States (75% by weight at Curtis Bay, Maryland, and 25% by weight at Hammond, Indiana). The material is stored in several configurations in over 21,000 drums. The U.S. Congress has declared the entire DNSC thorium nitrate stockpile to be in excess of the needs of the Department of Defense. Part of DNSC's mission is to safely manage the continued storage, future sales, and/or disposition of the thorium nitrate stockpile. Historically, DNSC has sold surplus thorium nitrate to domestic and foreign companies, but there is no demand currently for this material. Analyses conducted by Oak Ridge National Laboratory (ORNL) in 2001 demonstrated that disposition of the thorium nitrate inventory as a containerized waste, without processing, is the least complex and lowest-cost option for disposition. A characterization study was conducted in 2002 by ORNL, and it was determined that the thorium nitrate stockpile may be disposed of as low-level waste. The Nevada Test Site (NTS) was used as a case study for the disposal alternative, and special radiological analyses and waste acceptance requirements were documented. Among the special radiological considerations is the emission of {sup 220}Rn and {sup 222}Rn from buried material. NTS has a performance objective on the emissions of radon: 20 pCi m{sup -2} sec{sup -1} at the surface of the disposal facility. The radon emissions from the buried thorium nitrate stockpile have been modeled. This paper presents background information and summarizes the results of modeling radon emissions and compares those results with the NTS performance objective.

  3. Indoor gamma radiation and radon concentrations in a Norwegian carbonatite area.

    PubMed

    Sundal, A V; Strand, T

    2004-01-01

    Results of indoor gamma radiation and radon measurements in 95 wooden dwellings located in a Norwegian thorium-rich carbonatite area using thermoluminescent dosemeters and CR-39 alpha track detectors, respectively, are reported together with a thorough analysis of the indoor data with regard to geological factors. Slightly enhanced radium levels and thorium concentrations of several thousands Bq kg(-1) in the carbonatites were found to cause elevated indoor radon-222 levels and the highest indoor gamma dose rates ever reported from wooden houses in Norway. An arithmetic mean indoor gamma dose rate of 200 nGy h(-1) and a maximum of 620 nGy h(-1) were obtained for the group of dwellings located directly on the most thorium-rich bedrock. PMID:15312702

  4. Atmospheric trend and lifetime of chlorodifluoromethane (HCFC-22) and the global tropospheric OH concentration

    NASA Astrophysics Data System (ADS)

    Miller, B. R.; Huang, J.; Weiss, R. F.; Prinn, R. G.; Fraser, P. J.

    1998-06-01

    Concentrations of CHClF2 (HCFC-22) in clean background air collected at Cape Grim, Tasmania, over the period 1978-1996, and at La Jolla, California, over the period 1992-1997, have been measured by oxygen-doped electron capture detection gas chromatography. The mid-1996 dry-air mole fractions and trends were 116.7 parts per trillion (ppt) and 6.0 ppt yr-1 in Cape Grim and 132.4 ppt and 5.5 ppt yr-1 in California, respectively. These observations, together with estimates of industrial emissions, have been fitted to a two-dimensional global atmospheric model by an optimal estimation inversion technique to yield estimated tropospheric and total atmospheric lifetimes for chemical destruction of CHClF2 of 9.1-2.8+4.4 years and 10.0-3.0+4.4 years, respectively. These lifetimes correspond to a temperature- and density-weighed global tropospheric OH abundance of 11.0-3.6+5.0 × 105 radical cm-3, which is in statistical agreement with our recent more accurate estimate of OH abundance based on measurements of CH3CCl3. Our analysis suggests that, compared to current industrial estimates, southern hemisphere emissions are higher, global emissions are larger in earlier years and smaller in later years, and, finally, production by nonreporting companies is less.

  5. Long-term trends in dissolved iron and DOC concentration linked to nitrate depletion in riparian soils

    NASA Astrophysics Data System (ADS)

    Musolff, Andreas; Selle, Benny; Fleckenstein, Jan H.; Oosterwoud, Marieke R.; Tittel, Jörg

    2016-04-01

    The instream concentrations of dissolved organic carbon (DOC) are rising in many catchments of the northern hemisphere. Elevated concentrations of DOC, mainly in the form of colored humic components, increase efforts and costs of drinking water purification. In this study, we evaluated a long-term dataset of 110 catchments draining into German drinking water reservoirs in order to assess sources of DOC and drivers of a potential long-term change. The average DOC concentrations across the wide range of different catchments were found to be well explained by the catchment's topographic wetness index. Higher wetness indices were connected to higher average DOC concentrations, which implies that catchments with shallow topography and pronounced riparian wetlands mobilize more DOC. Overall, 37% of the investigated catchments showed a significant long-term increase in DOC concentrations, while 22% exhibited significant negative trends. Moreover, we found that increasing trends in DOC were positively correlated to trends in dissolved iron concentrations at pH≤6 due to remobilization of DOC previously sorbed to iron minerals. Both, increasing trends in DOC and dissolve iron were found to be connected to decreasing trends and low concentrations of nitrate (below ~6 mg/L). This was especially observed in forested catchments where atmospheric N-depositions were the major source for nitrate availability. In these catchments, we also found long-term increases of phosphate concentrations. Therefore, we argue that dissolved iron, DOC and phosphate were jointly released under iron-reducing conditions when nitrate as a competing electron acceptor was too low in concentrations to prevent the microbial iron reduction. In contrast, we could not explain the observed increasing trends in DOC, iron and phosphate concentrations by the long-term trends of pH, sulfate or precipitation. Altogether this study gives strong evidence that both, source and long-term increases in DOC are

  6. Difference in concentration trends of airborne particulate matter during rush hour on weekdays and Sundays in Tokyo, Japan.

    PubMed

    Hara, Kunio; Homma, Junichi; Tamura, Kenji; Inoue, Mariko; Karita, Kanae; Kondo, Yoshinori; Yano, Eiji

    2014-09-01

    Suspended particulate matter (SPM) and fine particulate matter (less than or equal to 2.5 microm: PM2.5) have generally been decreasing for the last decade in Tokyo, Japan. To elucidate the major cause of this decrease, the authors investigated the different trends of airborne particulates (both SPM and PM2.5 concentrations) by evaluating comparisons based on the location of the monitoring stations (roadside vs. ambient), days of the week (weekdays vs. Sundays), and daily fluctuation patterns (2002 vs. 2010). Hourly mean SPM and PM2.5 concentrations were obtained at four monitoring stations (two roadside stations, two ambient stations) in Tokyo, Japan. Annual mean concentrations of each day of the week and of each hour of the day from 2002 to 2010 were calculated. The results showed that (1) the daily differences in annual mean concentration decreased only at the two roadside monitoring stations; (2) the high hourly mean concentrations observed on weekdays during the daily rush hour at the two roadside monitoring stations observed in 2002 diminished in 2010; (3) the SPM concentration that decreased the most since 2002 was the PM2.5 concentration; and (4) the fluctuation of hourly concentrations during weekdays at the two roadside monitoring stations decreased. A decreasing trend of airborne particulates during the daily rush hour in Tokyo, Japan, was observed at the roadside monitoring stations on weekdays since 2002. The decreasing PM2.5 concentration resulted in this decreasing trend of airborne particulate concentrations during the daily rush hours on weekdays, which indicates fewer emissions were produced by diesel vehicles. Implications: The authors compared the trends of SPM and PM2.5 in Tokyo by location (roadside vs. ambient), days of the week (weekdays vs. Sundays), and daily fluctuation patterns (2002 vs. 2010). The high hourly mean concentrations observed at the roadside location during rush hour on weekdays in 2002 diminished in 2010. The SPM

  7. TRENDS IN DIOXIN AND PCB CONCENTRATIONS IN MEAT SAMPLES FROM SEVERAL DECADES OF THE 20TH CENTURY

    EPA Science Inventory

    Data from several studies suggest that concentrations of dioxins rose in the environment from the 1930s to about the 1960s/70s and have been declining over the last decade or two. The most direct evidence of this trend is lake core sediments, with some other evidence from older...

  8. Trends in radionuclide concentrations for selected wildlife and food products near the Hanford Site from 1971 through 1988

    SciTech Connect

    Eberhardt, L.E.; Cadwell, L.L.; Price, K.R.; Carlile, D.W.; Alaska Dept. of Fish and Game, Juneau, AK )

    1989-09-01

    From 1971 through 1988 at least 40 species of wildlife and 27 different types of food products were collected and analyzed for radionuclides as part of the Pacific Northwest Laboratory (PNL) Environmental Monitoring Program. This report summarizes the results of these analyses for sample types collected for all or most of the 18-year period. The objectives of this summary investigation were to identify long-term trends or significant year-to-year changes in radionuclide concentrations and, if possible, relate any observed changes in radionuclide concentrations to their sources and probable causes. Statistical techniques were employed to test for long-term trends. Conspicuous short-term changes in radionuclide concentrations were identified from inspection of the data. 30 refs., 16 figs., 4 tabs.

  9. Status and trends in concentrations of contaminants and measures of biological stress in San Francisco Bay. Technical memo

    SciTech Connect

    Long, E.; MacDonald, D.; Matta, M.B.; VanNess, K.; Buchman, M.

    1988-05-01

    Under the National Status and Trends (NS T) Program, the National Oceanic and Atmospheric Administration (NOAA) monitors the occurrence of certain contaminants and indicators of biological stress at approximately 200 sites in the United States. The Program was initiated in 1984 to provide an internally consistent data base for assessing the condition of parts of the Nation's coastal and estuarine environments. The Program thus far has focused largely upon generation of chemical contaminant data for sediments, fish, and bivalves, and certain analyses of these data. The results of the initial analyses are summarized in progress reports (NOAA, 1987a and b). The objectives of the report are to: (1) portray geographic trends in the concentrations of contaminants and the prevalence of selected measures of biological effects; (2) portray temporal trends in concentrations of contaminants and prevalence of selected measures of biological effects; (3) relate selected measures of biological effects to the concentrations of contaminants; and (4) compare the trends observed in available historical data to compatible recent measurements made by NOAA in San Francisco Bay. These objectives will be met through evaluation of data collected by NOAA and the many others who have studied the conditions in San Fransisco Bay. Some of the data from the NOAA NS T Program will be reported for the first time in the report.

  10. 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.

  11. Occurrence, Distribution, Sources, and Trends of Elevated Chloride Concentrations in the Mississippi River Valley Alluvial Aquifer in Southeastern Arkansas

    USGS Publications Warehouse

    Kresse, Timothy M.; Clark, Brian R.

    2008-01-01

    Water-quality data from approximately 2,500 sites were used to investigate the distribution of chloride concentrations in the Mississippi River Valley alluvial aquifer in southeastern Arkansas. The large volume and areal distribution of the data used for the investigation proved useful in delineating areas of elevated (greater than 100 milligrams per liter) chloride concentrations, assessing potential sources of saline water, and evaluating trends in chloride distribution and concentration over time. Irrigation water containing elevated chloride concentrations is associated with negative effects to rice and soybeans, two of the major crops in Arkansas, and a groundwater chloride concentration of 100 milligrams per liter is recommended as the upper limit for use on rice. As such, accurately delineating areas with high salinity ground water, defining potential sources of chloride, and documenting trends over time is important in assisting the agricultural community in water management. The distribution and range of chloride concentrations in the study area revealed distinct areas of elevated chloride concentrations. Area I includes an elongated, generally northwest-southeast trending band of moderately elevated chloride concentrations in the northern part of the study area. This band of elevated chloride concentrations is approximately 40 miles in length and varies from approximately 2 to 9 miles in width, with a maximum chloride concentration of 360 milligrams per liter. Area II is a narrow, north-south trending band of elevated chloride concentrations in the southern part of the study area, with a maximum chloride concentration of 1,639 milligrams per liter. A zone of chloride concentrations exceeding 200 milligrams per liter is approximately 25 miles in length and 5 to 6 miles in width. In Area I, low chloride concentrations in samples from wells completed in the alluvial aquifer next to the Arkansas River and in samples from the upper Claiborne aquifer, which

  12. Trends in nutrient concentration and load for streams in the Mississippi River basin 1974-94

    USGS Publications Warehouse

    Lurry, Dee L.; Dunn, David E.

    1997-01-01

    The mean annual yields were computed from the estimated mean annual loads. Mean annual nitrogen yields are largest for three watersheds in the upper Mississippi Basin; estimated yield of each is greater than 5.0 tons per square mile. Nine stations in the Ohio River Basin have estimated mean annual nitrogen yields greater than 2.0 tons per square mile. Estimated mean annual phosphorus yield is greater than 0.250 ton per square mile at 7 stations, 5 in the Ohio Basin and 2 in the upper Mississippi Basin. Statistically significant trends in annual streamflow were detected at seven stations. Annual streamflow influences trends in load, even when the streamflow trends are not statistically significant.

  13. Distribution of 222Rn concentration in an inhabited area adjacent to the Aja granitic heights of Hail Province, Saudi Arabia.

    PubMed

    Kinsara, Abdulraheem Abdulrahman; Shabana, El-Said Ibrahim; Abulfaraj, Waleed Hussain; Qutub, Maher Mohammad Taher

    2015-01-01

    Radon-222 has been measured in groundwater, dwellings, and atmosphere of an inhabited area adjacent to the granitic Aja heights of Hail province, Saudi Arabia. The measurements were carried out in the field using a RAD7 instrument. Twenty-eight water samples, collected from drilled wells scattered in the region, were analyzed. Radon-222 concentration ranged from 2.5-95 kBq m(-3) with an average value of about 30.3 kBq m(-3). The higher values were found in wells drawing water from granitic aquifers. Indoor 222Rn was measured in 20 dwellings of rural areas in Hail city and other towns. Concentrations ranged from 12-125.6 Bq m(-3), with an average value of 54.6 Bq m(-3). Outdoor air 222Rn was measured at 16 sites, with values ranging from 6.2-13.3 Bq m(-3), with an average value of 10.5 Bq m(-3). The estimated average effective dose due to inhalation of 222Rn released from water was 0.08 mSv y(-1). The estimated average annual effective dose due to indoor 222Rn was 1.35 mSv, which lies below the effective dose range (3-10 mSv) given as the recommended action level. Based on the average dose rate values, the excess lifetime cancer risk values were estimated as 69.8 × 10(-4) due to indoor radon and 13.4 × 10(-4) due to outdoor radon. PMID:25437521

  14. Distribution of 222Rn concentration in an inhabited area adjacent to the Aja granitic heights of Hail Province, Saudi Arabia.

    PubMed

    Kinsara, Abdulraheem Abdulrahman; Shabana, El-Said Ibrahim; Abulfaraj, Waleed Hussain; Qutub, Maher Mohammad Taher

    2015-01-01

    Radon-222 has been measured in groundwater, dwellings, and atmosphere of an inhabited area adjacent to the granitic Aja heights of Hail province, Saudi Arabia. The measurements were carried out in the field using a RAD7 instrument. Twenty-eight water samples, collected from drilled wells scattered in the region, were analyzed. Radon-222 concentration ranged from 2.5-95 kBq m(-3) with an average value of about 30.3 kBq m(-3). The higher values were found in wells drawing water from granitic aquifers. Indoor 222Rn was measured in 20 dwellings of rural areas in Hail city and other towns. Concentrations ranged from 12-125.6 Bq m(-3), with an average value of 54.6 Bq m(-3). Outdoor air 222Rn was measured at 16 sites, with values ranging from 6.2-13.3 Bq m(-3), with an average value of 10.5 Bq m(-3). The estimated average effective dose due to inhalation of 222Rn released from water was 0.08 mSv y(-1). The estimated average annual effective dose due to indoor 222Rn was 1.35 mSv, which lies below the effective dose range (3-10 mSv) given as the recommended action level. Based on the average dose rate values, the excess lifetime cancer risk values were estimated as 69.8 × 10(-4) due to indoor radon and 13.4 × 10(-4) due to outdoor radon.

  15. Linking diurnal trends in methylmercury concentration and organic matter photo-reactivity in wetlands of the Yolo Bypass, California

    NASA Astrophysics Data System (ADS)

    Fleck, J. A.; Downing, B. D.; Saraceno, J.; Gill, G.; Stephenson, M.; Bergamaschi, B. A.

    2008-12-01

    Aqueous concentrations of methylmercury (MeHg) are known to vary temporally and spatially due to multiple concurrent production and loss mechanisms, and due to variations in the hydrologic connectivity between the methylating substrate (most commonly the benthos) and the overlying water compartments. Diurnal trends in MeHg production, bacterial demethylation, photo-demethylation, diffusion and advection transport processes have been identified and investigated; however, the magnitude and relative importance of each process in mediating overlying water MeHg concentrations, is not well known in natural wetland systems. Temporal variations in aqueous MeHg concentrations may impact the biological accumulation of MeHg into the base of the aquatic food chain, and may challenge regulatory efforts designed to mitigate MeHg exports from point and non-point sources. To identify the possible "hot moments" during the diurnal cycle, surface water MeHg concentrations were monitored in two agricultural wetland settings (wild rice and white rice fields) over a 24- hour period within the Yolo Bypass Wildlife Area, California using a combination of in situ optical sensors and traditional surface-water grab samples. In the wild rice field, MeHg concentrations doubled from 1 ng/L to 2 ng/L over the nighttime hours and returned to 1 ng/L during the daylight hours, whereas the white rice field showed no significant variation in MeHg concentration (0.73 +/- 0.08 ng/L) throughout the diurnal cycle. Similar trends were observed when MeHg data was expressed as a percentage of total Hg, with both wetland habitats exhibiting similar levels (20% MeHg) following the nighttime period and the wild rice field declining to 10% in the early evening. Field parameters measured in situ (including: solar radiation, pH, dissolved oxygen, and temperature) exhibited large diurnal trends in both wetlands, whereas optical proxies for dissolved organic matter (DOM) composition mirrored the fluctuations in Me

  16. Trends in agricultural ammonia emissions and ammonium concentrations in precipitation over the Southeast and Midwest United States

    NASA Astrophysics Data System (ADS)

    Stephen, Konarik; Aneja, Viney P.

    Emissions from agricultural activities, both crop and animal, are known to contain gaseous ammonia (NH 3) which through chemical reaction in rainwater changes into ammonium ion (NH 4+). Using wet deposition data of ammonium from several National Atmospheric Deposition Program/National Trends Network (NADP/NTN) and ambient levels of ammonium from Clean Air Status Trends Network (CAST Net) sites as well as calculated NH 3 emissions from North Carolina, and the Southeast and Midwest regions of the United States, trends in ammonium concentrations in precipitation were analyzed for the period of 1983-2004. The beginning of 1997 coincides with the implementation of a swine population moratorium in the state of North Carolina. Results from the analysis in North Carolina indicate a lessening in the rate of increases in NH 4+ concentration in precipitation since the moratorium went into effect. Sampson County, NC, saw stable NH 4+ concentrations from 1983 to 1989, an average rise of 9.5% from 1989 to 1996, and an average increase of only 4% from 1997 to 2004. In addition, HYSPLIT back-trajectory model was used to determine that when ambient air in downwind sites arrived from the high NH 3 emissions source region, ammonium concentrations in precipitation were enhanced. For the Southeast United States domain, analysis shows that NH 4+ concentrations generally increased with increasing NH 3 emissions from within the same region. Similar analysis has been performed over the Midwest United States and compared to the results from the Southeast United States. Emissions from the Midwest are attributed to larger animals, including hogs and cattle, whereas the Southeast has a higher percentage of emissions coming from smaller livestock, such as chickens. In addition, the states of the Midwest United States have a much more uniform spatial distribution of emissions.

  17. Trends in nitrogen concentrations and load in 48 minor streams draining intensively farmed Danish catchments, 1990-2014. How can the observed trend be explained?

    NASA Astrophysics Data System (ADS)

    Windolf, Jørgen; Børgesen, Christen; Blicher-Mathiesen, Gitte; Kronvang, Brian; Larsen, Søren E.; Tornbjerg, Henrik

    2016-04-01

    The total land-based nitrogen load to Danish coastal waters has decreased by 50% since 1990 through a reduction of the outlet of nitrogen from sewage point sources and diffuse sources. On a national scale nitrogen load from diffuse sources, has been reduced by 43% , mainly due to limitation of the amount of N input to different crops, rules for timing and application of manure, mandatory demands for catch crops and restoration of wetlands. The latter increasing the nitrogen retention capacity in surface waters. However, on a local scale huge variations exist in the reduction of the diffuse nitrogen load. Since 1990, an important part of the Danish national monitoring program on the aquatic environment (NOVANA) has been directed at quantifying the nitrogen concentrations and load in 48 minor streams draining small intensively farmed catchments. The 48 catchments have a mean size of 18 km2, farmed area constitutes more than 60% of the catchment area and the catchments have no significant outlets of sewage to the streams. The statistical trend results (based on a seasonal Mann-Kendall) from these 48 streams show a 9-65% reduction in the diffuse nitrogen load (mean: 48%). The large differences in trends in the diffuse N load are related to differences in catchment-specific variables such as nitrogen surpluses, nitrogen leaching from the root zone, hydrogeology and nitrogen retention in ground and surface waters.

  18. Atmospheric Trends and Lifetime of CH3CCI3 and Global OH Concentrations.

    PubMed

    Prinn, R G; Weiss, R F; Miller, B R; Huang, J; Alyea, F N; Cunnold, D M; Fraser, P J; Hartley, D E; Simmonds, P G

    1995-07-14

    Determination of the atmospheric concentrations and lifetime of trichloroethane (CH(3)CCI(3)) is very important in the context of global change. This halocarbon is involved in depletion of ozone, and the hydroxyl radical (OH) concentrations determined from its lifetime provide estimates of the lifetimes of most other hydrogen-containing gases involved in the ozone layer and climate. Global measurements of trichloroethane indicate rising concentrations before and declining concentrations after late 1991. The lifetime of CH(3)CCI(3) in the total atmosphere is 4.8 +/- 0.3 years, which is substantially lower than previously estimated. The deduced hydroxyl radical concentration, which measures the atmosphere's oxidizing capability, shows little change from 1978 to 1994.

  19. Trends in Streamflow and Nutrient and Suspended-Sediment Concentrations and Loads in the Upper Mississippi, Ohio, Red, and Great Lakes River Basins, 1975-2004

    USGS Publications Warehouse

    Lorenz, David L.; Robertson, Dale M.; Hall, David W.; Saad, David A.

    2009-01-01

    Many actions have been taken to reduce nutrient and suspended-sediment concentrations and the amount of nutrients and sediment transported in streams as a result of the Clean Water Act and subsequent regulations. This report assesses how nutrient and suspended-sediment concentrations and loads in selected streams have changed during recent years to determine if these actions have been successful. Flow-adjusted and overall trends in concentrations and trends in loads from 1993 to 2004 were computed for total nitrogen, dissolved ammonia, total organic nitrogen plus ammonia, dissolved nitrite plus nitrate, total phosphorus, dissolved phosphorus, total suspended material (total suspended solids or suspended sediment), and total suspended sediment for 49 sites in the Upper Mississippi, Ohio, Red, and Great Lakes Basins. Changes in total nitrogen, total phosphorus, and total suspended-material loads were examined from 1975 to 2003 at six sites to provide a longer term context for the data examined from 1993 to 2004. Flow-adjusted trends in total nitrogen concentrations at 19 of 24 sites showed tendency toward increasing concentrations, and overall trends in total nitrogen concentrations at 16 of the 24 sites showed a general tendency toward increasing concentrations. The trends in these flow-adjusted total nitrogen concentrations are related to the changes in fertilizer nitrogen applications. Flow-adjusted trends in dissolved ammonia concentrations from 1993 to 2004 showed a widespread tendency toward decreasing concentrations. The widespread, downward trends in dissolved ammonia concentrations indicate that some of the ammonia reduction goals of the Clean Water Act are being met. Flow-adjusted and overall trends in total organic plus ammonia nitrogen concentrations from 1993 to 2004 did not show a distinct spatial pattern. Flow-adjusted and overall trends in dissolved nitrite plus nitrate concentrations from 1993 to 2004 also did not show a distinct spatial pattern

  20. Long-term trends in nitrogen isotope composition and nitrogen concentration in brazilian rainforest trees suggest changes in nitrogen cycle.

    PubMed

    Hietz, Peter; Dünisch, Oliver; Wanek, Wolfgang

    2010-02-15

    Direct or indirect anthropogenic effects on ecosystem nitrogen cycles are important components of global change. Recent research has shown that N isotopes in tree rings reflect changes in ecosystem nitrogen sources or cycles and can be used to study past changes. We analyzed trends in two tree species from a remote and pristine tropical rainforest in Brazil, using trees of different ages to distinguish between the effect of tree age and long-term trends. Because sapwood differed from heartwood in delta(15)N and N concentration and N can be translocated between living sapwood cells, long-term trends are best seen in dead heartwood. Heartwood delta(15)N in Spanish cedar (Cedrela odorata) and big-leaf mahogany (Swietenia macrophylla) increased with tree age, and N concentrations increased with age in Cedrela. Controlling for tree age, delta(15)N increased significantly during the past century even when analyzing only heartwood and after removing labile N compounds. In contrast to northern temperate and boreal forests where wood delta(15)N often decreased, the delta(15)N increase in a remote rainforest is unlikely to be a direct signal of changed N deposition. More plausibly, the change in N isotopic composition indicates a more open N cycle, i.e., higher N losses relative to internal N cycling in the forest, which could be the result of changed forest dynamics.

  1. Analysis of the influence of solar activity and atmospheric factors on 7Be air concentration by seasonal-trend decomposition

    NASA Astrophysics Data System (ADS)

    Bas, M. C.; Ortiz, J.; Ballesteros, L.; Martorell, S.

    2016-11-01

    7Be air concentrations were measured at the Universitat Politècnica de Valencia campus (in the east of Spain) during the period 2007-2014. The mean values of monthly 7Be concentrations ranged from 2.65 to 8.11 mBq/m3, showing significant intra and interannual variability. A seasonal-trend decomposition methodology was applied to identify the trend-cycle, seasonal and irregular components of the 7Be time series. The decomposition model makes it possible to estimate the influence of solar activity and atmospheric factors on the independent components, in order to find the different sources of 7Be variability. The results show that solar activity is a factor with a high inverse influence on the trend-cycle pattern of 7Be variability. Solar radiation, temperature and relative humidity are positive influential factors on the seasonal 7Be variation with a regular pattern over the years. Finally, the irregular component presents a significant negative correlation with precipitation and wind speed parameters, which have an irregular behavior over the years and seasons.

  2. Long-term trends in California mobile source emissions and ambient concentrations of black carbon and organic aerosol.

    PubMed

    McDonald, Brian C; Goldstein, Allen H; Harley, Robert A

    2015-04-21

    A fuel-based approach is used to assess long-term trends (1970-2010) in mobile source emissions of black carbon (BC) and organic aerosol (OA, including both primary emissions and secondary formation). The main focus of this analysis is the Los Angeles Basin, where a long record of measurements is available to infer trends in ambient concentrations of BC and organic carbon (OC), with OC used here as a proxy for OA. Mobile source emissions and ambient concentrations have decreased similarly, reflecting the importance of on- and off-road engines as sources of BC and OA in urban areas. In 1970, the on-road sector accounted for ∼90% of total mobile source emissions of BC and OA (primary + secondary). Over time, as on-road engine emissions have been controlled, the relative importance of off-road sources has grown. By 2010, off-road engines were estimated to account for 37 ± 20% and 45 ± 16% of total mobile source contributions to BC and OA, respectively, in the Los Angeles area. This study highlights both the success of efforts to control on-road emission sources, and the importance of considering off-road engine and other VOC source contributions when assessing long-term emission and ambient air quality trends. PMID:25793355

  3. Long-term trends in California mobile source emissions and ambient concentrations of black carbon and organic aerosol.

    PubMed

    McDonald, Brian C; Goldstein, Allen H; Harley, Robert A

    2015-04-21

    A fuel-based approach is used to assess long-term trends (1970-2010) in mobile source emissions of black carbon (BC) and organic aerosol (OA, including both primary emissions and secondary formation). The main focus of this analysis is the Los Angeles Basin, where a long record of measurements is available to infer trends in ambient concentrations of BC and organic carbon (OC), with OC used here as a proxy for OA. Mobile source emissions and ambient concentrations have decreased similarly, reflecting the importance of on- and off-road engines as sources of BC and OA in urban areas. In 1970, the on-road sector accounted for ∼90% of total mobile source emissions of BC and OA (primary + secondary). Over time, as on-road engine emissions have been controlled, the relative importance of off-road sources has grown. By 2010, off-road engines were estimated to account for 37 ± 20% and 45 ± 16% of total mobile source contributions to BC and OA, respectively, in the Los Angeles area. This study highlights both the success of efforts to control on-road emission sources, and the importance of considering off-road engine and other VOC source contributions when assessing long-term emission and ambient air quality trends.

  4. Lead-lag relationships between atmospheric trends of temperature and carbon dioxide concentrations during the pliocene

    NASA Astrophysics Data System (ADS)

    Vakulenko, N. V.; Kotlyakov, V. M.; Sonechkin, D. M.

    2016-04-01

    Reconstructions of the average global near-surface air temperature and carbon dioxide concentration in the atmosphere for the late Pliocene are compared. For this purpose, a special technique of multiscale analysis based on wavelets was developed. It is found that temperature changes on timescales of 100 to 500 kyr lead the respective changes in the carbon dioxide concentration at about 10-25 kyr. It means that these reconstructions cannot be used for assessing the climate sensitivity to changes in the carbon dioxide concentration.

  5. Trends in chemical concentration in sediment cores from three lakes in New Jersey and one lake on Long Island, New York

    USGS Publications Warehouse

    Long, Gary R.; Ayers, Mark A.; Callender, Edward; Van Metre, Peter C.

    2003-01-01

    Data from this study indicate that changes in population, land use, and chemical use in the urbanized watersheds over the period of sedimentary record have contributed to upward trends in concentrations of trace elements and hydrophobic organic compounds. Although downward trends were observed for some constituents in the years after their concentrations peaked, concentrations of most constituents in urban lake cores were higher in the most recently deposited sediments than at the base of each respective core and in the reference lake cores. Similar trends in concentrations of these constituents have been observed in sediment cores from other urban lakes across the United States.

  6. Seasonal and diurnal trends in concentrations and fluxes of volatile organic compounds in central London

    NASA Astrophysics Data System (ADS)

    Valach, A. C.; Langford, B.; Nemitz, E.; MacKenzie, A. R.; Hewitt, C. N.

    2015-07-01

    Concentrations and fluxes of seven volatile organic compounds (VOCs) were measured between August and December 2012 at a rooftop site in central London as part of the ClearfLo project (Clean Air for London). VOC concentrations were quantified using a proton transfer reaction mass spectrometer (PTR-MS) and fluxes were calculated using a virtual disjunct eddy covariance technique. The median VOC fluxes, including aromatics, oxygenated compounds and isoprene, ranged from 0.07 to 0.33 mg m-2 h-1. Median mixing ratios were 7.3 ppb for methanol and < 1 ppb for the other compounds. Strong relationships were observed between the fluxes and concentrations of some VOCs with traffic density and between the fluxes and concentrations of isoprene and oxygenated compounds with photosynthetically active radiation (PAR) and temperature. An estimated 50-90 % of the fluxes of aromatic VOCs were attributable to traffic activity, which showed little seasonal variation, suggesting that boundary layer effects or possibly advected pollution may be the primary causes of increased concentrations of aromatics in winter. Isoprene, methanol and acetaldehyde fluxes and concentrations in August and September showed high correlations with PAR and temperature, when fluxes and concentrations were largest suggesting that biogenic sources contributed to their fluxes. Modelled biogenic isoprene fluxes from urban vegetation using the Guenther et al. (1995) algorithm agreed well with measured fluxes in August and September. Comparisons of estimated annual benzene emissions from both the London and the National Atmospheric Emissions Inventories agreed well with measured benzene fluxes. Flux footprint analysis indicated emission sources were localised and that boundary layer dynamics and source strengths were responsible for temporal and spatial VOC flux and concentration variability during the measurement period.

  7. Trends in trace organic and metal concentrations in the Pechora and Kara Seas and adjacent rivers

    SciTech Connect

    Brooks, J.M.; Champ, M.A.; Wade, T.L.; Kennicutt, M.C. II; Chambers, L.; Davis, T.

    1995-12-31

    Trace organic (pesticides, PCBs, PAHs and dioxin/furan) and trace metal concentrations have been measured in surficial sediment and tissue (i.e., clam, fish liver and flesh) samples from the Pechora and Kara Seas and their adjacent rivers -- Pechora, Ob and Yenisey Rivers. Total PAH, PCB and total DDT and chlordane concentrations ranged in surficial sediments from n.d. to 810 ppb, n.d.--8.7 ppb, n.d.--1.2 ppb, and n.d.--1.2 ppb, respectively, in a suite of 40 samples from the Kara Sea and its adjacent rivers. The highest concentrations of many of the trace organic and metal contaminants were found in the lower part of the Yenisey River below the salt wedge. Some trace metals (As for example) were elevated in the Pechora River dispositional plume region. Dioxin ranged from 1.36 to 413 ppt in a subset of 20 sediment samples. Higher trace organic contaminant concentrations compared to sediments were found in tissue samples from the region, especially fish liver samples. Concentrations as high as 1,114 ppb total PAHs, 89 ppb chlordane, 1,011 ppb for total DDT and 663 ppb PCBs were found in some fish liver samples. Dioxin concentrations in tissue samples ranged from 11.7 to 61 ppt. Concentrations of many trace organic and metal contaminants in these Russian marginal seas are influenced by inputs from these large Arctic rivers. Many organic contaminant concentrations in sediments are low, however detecting these compounds in tissue show they are bioavailable.

  8. Seasonal trends in concentrations and fluxes of volatile organic compounds above central London

    NASA Astrophysics Data System (ADS)

    Valach, A. C.; Langford, B.; Nemitz, E.; MacKenzie, A. R.; Hewitt, C. N.

    2015-03-01

    Concentrations and fluxes of seven volatile organic compounds (VOCs) were measured between August and December 2012 at a roof-top site in central London as part of the ClearfLo project (Clean Air for London). VOC concentrations were quantified using a proton transfer reaction-mass spectrometer and fluxes were calculated using a virtual disjunct eddy covariance technique. The median VOC fluxes, including aromatics, oxygenated compounds and isoprene, ranged from 0.07 to 0.33 mg m-2 h-1 and mixing ratios were 7.27 ppb for methanol (m / z 33) and <1 ppb for the remaining compounds. Strong relationships were observed between most VOC fluxes and concentrations with traffic density, but also with photosynthetically active radiation (PAR) and temperature for the oxygenated compounds and isoprene. An estimated 50-90 % of aromatic fluxes were attributable to traffic activity, which showed little seasonal variation, suggesting boundary layer effects or possibly advected pollution may be the primary causes of increased concentrations of aromatics in winter. PAR and temperature-dependent processes accounted for the majority of isoprene, methanol and acetaldehyde fluxes and concentrations in August and September, when fluxes and concentrations were largest. Modelled biogenic isoprene fluxes using the G95 algorithm agreed well with measured fluxes in August and September, due to urban vegetation. Comparisons of estimated annual benzene emissions from the London and National Atmospheric Emissions Inventory agreed well with measured benzene fluxes. Flux footprint analysis indicated emission sources were localized and that boundary layer dynamics and source strengths were responsible for temporal and spatial VOC flux and concentration variability during the measurement period.

  9. Long-term trends of benzo(a)pyrene concentration on the eastern coast of the Baltic Sea

    NASA Astrophysics Data System (ADS)

    Milukaite, Audrone R.

    Concentration of benzo(a)pyrene (B(a)P) was investigated in atmospheric air at Preila background station located on the eastern coast of the Baltic Sea in 1980-2002. A significant difference in daily concentration of benzo(a)pyrene, reaching more than two orders of magnitude, was determined during the period of investigation. The variability of benzo(a)pyrene daily concentration was considered. The main part of extreme benzo(a)pyrene daily concentration of over 5 ng m -3 was related to the air masses coming to the background site from W-SW to N-NW over the period of 1980-1994. Owing to the variability of benzo(a)pyrene daily concentration, the monthly concentration of benzo(a)pyrene in atmospheric air of the background site varied from 0.18 to 3.30 ng m -3 in cold season and from 0.02 to 1.72 ng m -3 in warm season. A slowly decreasing trend of benzo(a)pyrene monthly concentration was determined in both seasons during the whole period of investigation. Comparison of B(a)P monthly concentration determined at Preila background station with that in other countries since 1994 (according to the EMEP program) has shown that monthly concentration of benzo(a)pyrene is nearly of the same level in the Czech Republic and it is by one order of magnitude higher than at Scandinavian background stations. The course of carcinogen concentration at Preila background station is similar to that of Swedish stations with tendency to decrease from 1999.

  10. Concentrations of 222Rn, 220Rn and their decay products measured in outdoor air in various rural zones (Morocco) by using solid-state nuclear track detectors and resulting radiation dose to the rural populations.

    PubMed

    Misdaq, M A; Amrane, M; Ouguidi, J

    2010-03-01

    Alpha and beta activities per unit volume of air due to radon ((222)Rn), thoron ((220)Rn) and their progenies were measured in the outdoor air at different locations in Morocco by using both CR-39 and LR-115 type II solid-state nuclear track detectors (SSNTDs). In addition, the radon concentration was continuously measured in one location by using the methods with SSNTDs and AlphaGuard counter. The influence of the geological and meteorological conditions as well as phosphate and building material dust on the radon concentration in the outdoor air of the areas studied was investigated. The committed equivalent doses due to (218)Po and (214)Po radon short-lived progeny were evaluated in different tissues of the respiratory tract of the members of the public from the inhalation of outdoor air. The annual effective dose due to radon short-lived progeny from the inhalation of outdoor air by the members of the rural population was estimated.

  11. Temporal trends of persistent organic pollutant concentrations in precipitation around the Great Lakes.

    PubMed

    Venier, Marta; Salamova, Amina; Hites, Ronald A

    2016-10-01

    The concentrations of polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and several chlorinated insecticides in precipitation have been measured in samples collected every month since 1997 at six sites on the shores of the North American Great Lakes. We report here the geometric mean concentrations for each of these compounds for each year and at each site. Assuming a first-order rate decline for these data, we have calculated the time it takes for these concentrations to decrease by half. The halving times are not statistically distinguishable among the sites. Overall, the observed halving times are 11 ± 2 years for the PCBs, 14 ± 3 years for the PAHs, 4.0 ± 0.2 for the hexachlorocyclohexanes, 8.0 ± 0.9 for the DDTs, 5.1 ± 0.8 for the chlordanes, and 8.4 ± 0.6 for the endosulfans. In general, the halving times calculated from precipitation concentrations agree with those calculated from atmospheric vapor and particle phase concentrations.

  12. Temporal trends of persistent organic pollutant concentrations in precipitation around the Great Lakes.

    PubMed

    Venier, Marta; Salamova, Amina; Hites, Ronald A

    2016-10-01

    The concentrations of polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and several chlorinated insecticides in precipitation have been measured in samples collected every month since 1997 at six sites on the shores of the North American Great Lakes. We report here the geometric mean concentrations for each of these compounds for each year and at each site. Assuming a first-order rate decline for these data, we have calculated the time it takes for these concentrations to decrease by half. The halving times are not statistically distinguishable among the sites. Overall, the observed halving times are 11 ± 2 years for the PCBs, 14 ± 3 years for the PAHs, 4.0 ± 0.2 for the hexachlorocyclohexanes, 8.0 ± 0.9 for the DDTs, 5.1 ± 0.8 for the chlordanes, and 8.4 ± 0.6 for the endosulfans. In general, the halving times calculated from precipitation concentrations agree with those calculated from atmospheric vapor and particle phase concentrations. PMID:26874551

  13. Temporal Trends of Insecticide Concentrations in Carpet Dust in California from 2001 to 2006.

    PubMed

    Gunier, Robert B; Nuckols, John R; Whitehead, Todd P; Colt, Joanne S; Deziel, Nicole C; Metayer, Catherine; Reynolds, Peggy; Ward, Mary H

    2016-07-19

    Active ingredients in residential and agricultural insecticides have changed over time, due in part to regulatory restrictions. Few studies have evaluated how changes in active ingredients have impacted insecticide levels measured in homes. We measured concentrations of insecticides in one carpet-dust sample from each of 434 homes in California from 2001 to 2006. Analytes included four insecticides sold for indoor home use during our study period (carbaryl, cypermethrin, permethrin, and propoxur) and four that are no longer sold for indoor use including dichlorodiphenyltrichloroethylene (DDT, removed from the market in 1972), chlordane (1988), chlorpyrifos (2001), and diazinon (2004). We considered other potential determinants of concentrations of insecticides in carpet dust, such as home and garden use, occupational exposure, and nearby agricultural applications. We calculated the percentage change in the concentration of each insecticide per year, adjusting for significant determinants. In adjusted models, concentrations of insecticides in carpet dust decreased for three of four insecticides no longer sold for residential use: chlordane (-15% per year), chlorpyrifos (-31%), diazinon (-48%), and propoxur (-34%), which is currently sold for residential use but with increased restrictions since 1997. Concentrations of other insecticides sold for indoor use (carbaryl, cypermethrin, and permethrin) and DDT did not change over time in our study population. PMID:27341453

  14. Spatial and seasonal trends in particle concentration and optical extinction in the United States

    NASA Astrophysics Data System (ADS)

    Malm, William C.; Sisler, James F.; Huffman, Dale; Eldred, Robert A.; Cahill, Thomas A.

    1994-01-01

    In the spring of 1988 an interagency consortium of Federal Land Managers and the Environmental Protection Agency initiated a national visibility and aerosol monitoring network to track spatial and temporal trends of visibility and visibility-reducing particles. The monitoring network consists of 36 stations located mostly in the western United States. The major visibility-reducing aerosol species, sulfates, nitrates, organics, light-absorbing carbon, and wind-blown dust are monitored as well as light scattering and extinction. Sulfates and organics are responsible for most of the extinction at most locations throughout the United States, while at sites in southern California nitrates are dominant. In the eastern United States, sulfates contribute to about two thirds of the extinction. In almost all cases, extinction and the major aerosol types are highest in the summer and lowest during the winter months.

  15. Interannual heavy element and nutrient concentration trends in the top sediments of Venice Lagoon (Italy).

    PubMed

    Masiol, Mauro; Facca, Chiara; Visin, Flavia; Sfriso, Adriano; Pavoni, Bruno

    2014-12-15

    The elemental composition of surficial sediments of Venice Lagoon (Italy) in 1987, 1993, 1998 and 2003 were investigated. Zn and Cr concentrations resulted in higher than background levels, but only Cd and Hg were higher than legal quality standards (Italian Decree 2010/260 and Water Framework Directive 2000/60/EC). Contaminants with similar spatial distribution are sorted into three groups by means of correlation analysis: (i) As, Co, Cd, Cu, Fe, Pb, Zn; (ii) Ni, Cr; (iii) Hg. Interannual concentrations are compared by applying a factor analysis to the matrix of differences between subsequent samplings. A general decrease of heavy metal levels is observed from 1987 to 1993, whereas particularly high concentrations of Ni and Cr are recorded in 1998 as a consequence of intense clam fishing, subsequently mitigated by better prevention of illegal harvesting. Due to the major role played by anthropogenic sediment resuspension, bathymetric variations are also considered.

  16. Lipid concentrations in Lake Michigan fishes: Seasonal, spatial, ontogenetic, and long-term trends

    USGS Publications Warehouse

    Madenjian, Charles P.; Elliott, Robert F.; DeSorcie, Timothy J.; Stedman, Ralph M.; O'Connor, Daniel V.; Rottiers, Donald V.

    2000-01-01

    Lipid concentrations were measured in seven species of fish from several locations in Lake Michigan during spring, summer, and fall in 1994 to 1995. Adult alewife (Alosa pseudoharengus) and age-2 coho salmon (Oncorhynchus kisutch) exhibited pronounced seasonal changes in lipid content. Adult alewives averaged 7.4% lipid, on a wet weight basis, during spring (May), 2.6% in summer (July), and 12.2% in fall (late September through October). Spring lipid concentration was low in age-2 coho salmon, averaging only 1.9%, then increased to 7.8% during summer and decreased to 4.5% by fall. In contrast, lipid content in adult bloater (Coregonus hoyi) was relatively constant with respect to season, ranging between 10.6% and 12.4% during the year. Lipid concentration increased with fish size for all species except rainbow smelt (Osmerus mordax). Although deepwater sculpin (Myoxocephalus thompsoni) were considerably larger than slimy sculpin (Cottus cognatus) (mean total length of 117 mm vs 68 mm), mean lipid content of deepwater sculpin (7.6%) was only slightly higher than that for slimy sculpin (6.6%). Comparison of lipid concentrations from this study with previous studies indicated that lipid concentration in lake trout (Salvelinus namaycush) and alewives in Lake Michigan did not change significantly from 1969–1971 to 1994–1995. Lipid concentration in large (about 250 mm total length) adult bloaters near Saugatuck (along the southeastern shore of the lake) decreased from 23.3% in 1980 to 11.9% in 1986, but showed no significant change between 1986 and 1994–1995.

  17. Trends in acetochlor concentrations in surface waters of the White River Basin, Indiana, 1994-96

    USGS Publications Warehouse

    Crawford, Charles G.

    1997-01-01

    Corn herbicides are used extensively in the White River Basin and account for about 70 percent of the total agricultural pesticide use in the basin. Acetochlor, a corn herbicide registered for use in 1994, is expected to reduce the total amount of corn herbicides used because of its broad-spectrum weed control and low use rates. Acetochlor is considered to be a probable human carcinogen, and its continued registration is contingent on concentrations in surface and ground water not exceeding target levels. During 1994, acetochlor was detected in only trace concentrations near the mouth of the White River and not at all in a small stream (93-square-mile drainage) in the northern part of the basin. By 1996, peak concentrations were about 2 and 3 micrograms per liter near the mouth of the White River and in the small stream, respectively. The estimated annual average concentration of acetochlor near the mouth of the White River in 1996 was 0.15 micrograms per liter, well below the 2 micrograms per liter criterion for surface-water supplied community-water systems.

  18. A PRINCIPAL COMPONENT ANALYSIS OF THE CLEAN AIR STATUS AND TRENDS NETWORK (CASTNET) AIR CONCENTRATION DATA

    EPA Science Inventory

    The spatial and temporal variability of ambient air concentrations of SO2, SO42-, NO3, HNO3, and NH4+ obtained from EPA's CASTNet was examined using an objective, statistically based technique...

  19. Differential trends in mercury concentrations in double-crested cormorant populations of the Canadian Prairies.

    PubMed

    Hall, Britt D; Doucette, Jennifer L; Bates, Lara M; Bugajski, Aleksandra; Niyogi, Som; Somers, Christopher M

    2014-04-01

    Mercury and selenium concentrations were measured in double-crested cormorants (Phalacrocorax auritus), piscivorous fish, and common prey items in five lakes in two ecoregions in Saskatchewan, Canada. Hg and Se concentrations in cormorants were within the natural ranges of birds living in un-impacted sites. Site explained a significant proportion of the variation in total Hg (THg) and methylmercury (MeHg) concentrations in both cormorant breast muscle and livers. Birds nesting on more northern lakes in the Boreal Plain ecoregion (THg range 0.11-1.06 and 0.26-9.27 μg g(-1) wet weight, for breast and liver respectively) had lower THg concentrations compared to those from lakes in the Prairie ecoregion (THg range 0.60-4.26 μg g(-1) ww and 1.59-25.11 μg g(-1), for breast and liver respectively). Concentrations of MeHg in livers was also lower in birds from northern sites (0.06-1.15 μg g(-1) ww) compared to those from prairie sites (0.22-4.06 μg g(-1) ww). We documented a wide range of %MeHg in livers (4.5-52 %), indicative of detoxifying MeHg via demethylation to inorganic Hg. Our data suggest that the threshold value where demethylation rates increase substantially appears to be ~10 μg g(-1) ww MeHg, similar to thresholds in other wildlife. Molar ratios of Hg:Se suggests that some birds from highly saline Reed Lake in the prairie region had insufficient Se available to bind to Hg, thereby removing Se binding as a mitigative strategy for high Hg levels for these birds. PMID:24515398

  20. Spatiotemporal trends in ground-level ozone concentrations and metrics in France over the time period 1999-2012.

    PubMed

    Sicard, Pierre; Serra, Romain; Rossello, Philippe

    2016-08-01

    The hourly ozone (O3) data from 332 background monitoring stations, spread in France, were analyzed over the period 1999-2012 and short-term trends were calculated. In the current climate change context, the calculation of human health- and vegetation-relevant metrics, and of associated trends, provides a consistent method to establish proper and effective policies to reduce the adverse O3 effects. The generation of optimal O3 maps, for risk and exposure assessment, is challenging. To overcome this issue, starting from a set of stations, a hybrid regression-interpolation approach was proposed. Annual surface O3 metrics, O3 human health metrics (number of exceedances of daily maximum 8-h values greater than 60 ppb and SOMO35) and O3 vegetation impact metrics (AOT40 for vegetation and forests) were investigated at individual sites. Citizens are more exposed to high O3 levels in rural areas than people living in the cities. The annual mean concentrations decreased by -0.12ppbyear(-1) at rural stations, and the significant reduction at 67% of stations, particularly during the warm season, in the number of episodic high O3 concentrations (e.g. 98th percentile, -0.19ppbyear(-1)) can be associated with the substantial reductions in NOx and VOCs emissions in the EU-28 countries since the early 1990s Inversely, the O3 background level is rising at 76% of urban sites (+0.14ppbyear(-1)), particularly during the cold period. This rise can be attributed to increases in imported O3 by long-range transport and to a low O3 titration by NO due to the reduction in local NOx emissions. The decrease in health-related and vegetation-relevant O3 metrics, at almost all stations, is driven by decreases in regional photochemical O3 formation and in peak O3 concentrations. The short-term trends highlight that the threat to population and vegetation declined between 1999 and 2012 in France, demonstrating the success of European control strategies over the last 20 years. However, for all

  1. Long term trends of CCN concentration in Arctic region at Zeppelin station, Ny-Ålesund, Svalbard

    NASA Astrophysics Data System (ADS)

    Jung, C. H.; Yoon, Y. J.; Kang, H. J.; Gim, Y. T.; Lee, B. Y.; Ström, J.; Krejci, R.; Tunved, P.

    2015-12-01

    The Arctic is a challenging region when assessing aerosol impacts due to their large variations in concentration, and varying chemical, physical and optical properties. In the climate effects of atmosphere aerosol indirect force, cloud condensation nuclei (CCN) play an important role because particles acting as they can grow to cloud droplets by condensation of water vapor, affecting cloud properties in various ways. For example, the increased CCN concentrations lead to the production of more numerous and smaller cloud drops, which can result in optically thicker clouds that tend to reflect more incoming solar radiation back to space (Twomey, 1977). Thus, investigating the physical process of the CCN aerosol that controls cloud droplet formation is important in understanding the radiative transfer and climate effect. In addition, there are still large variabilities in Arctic CCN number concentrations remaining. These variabilities are mainly due to the result of varying aerosol sources and chemical composition (Browse et al., 2012). Especially, the analysis on the long term trends as well as seasonality of CCN and relation with aerosols are very rare and need to be investigated. In this study, CCN concentration data collected at the Zeppelin observatory located on the top of Mt. Zeppelin, Svalbard (78° 54' N, 11° 53' E) are analyzed during 2007-2013. The seasonal and yearly trends of CCN in the Arctic region during the long periods are presented. The obtained results are compared with other instrumental data such as aerosol size distribution and total number concentration. ReferenceBrowse, J., Carslaw, K. S., Arnold, S. R., Pringle, K., and Boucher, O, 2012, The scavenging processes controlling the seasonal cycle in Arctic sulphate and black carbon aerosol, Atmos. Chem. Phys., 12, 6775-6798. Twomey, S., 1977: Atmospheric Aerosols. Elsevier.

  2. Linking Groundwater Age and Chemistry Data to Determine Redox Reaction Rates and Trends in Nitrate Concentrations in Agricultural Areas. (Invited)

    NASA Astrophysics Data System (ADS)

    Tesoriero, A. J.; Puckett, L.

    2009-12-01

    Use of industrially fixed nitrogen (N) fertilizer for agricultural purposes has increased dramatically, both in the United States (U.S.) and globally, since 1945. As a result, there has been growing concern about the consequences of increases in the amounts of anthropogenic N circulating in the atmosphere, hydrosphere, and biosphere. The U.S. Geological Survey’s National Water-Quality Assessment Program has collected groundwater samples along flow paths in more than 20 agricultural areas covering a range in hydrogeologic settings to evaluate the trends and transformations of agricultural chemicals. Historical trends in nitrogen fluxes to groundwater were evaluated by relating the recharge dates of groundwater samples, estimated using tracer (e.g., chlorofluorocarbon) concentrations, with concentrations of nitrate at the time of recharge, estimated by summing the molar concentrations of the parent compound (nitrate) and its transformation product (excess N2) in the age-dated sample. Results from this analysis indicate that median nitrate (NO3-) concentrations in recharge have increased markedly over the last 50 years: increasing from 4 mg/L (as N) in samples that recharged prior to 1983 to 7.5 mg/L (as N) in samples that recharged since 1983. Trends in nitrate concentrations in recharging groundwater were related to increases in the amount of fertilizer applied. Estimates of the portion of applied N reaching the water table ranged from 4 to 49% among the sites, with a median value of 14%. The fate of NO3- and many other groundwater contaminants is dependent on aquifer redox conditions. The reduction of oxygen is the most energetically favorable reaction that microorganisms use to oxidize organic material or other electron donors (e.g., pyrite). As a result, other reduction reactions (e.g., denitrification) affecting contaminant transport typically do not occur until most dissolved oxygen (DO) has been consumed. To improve assessments of contaminant transformations

  3. Monitoring Stream Nutrient Concentration Trends in a Mixed-Land-Use Watershed

    NASA Astrophysics Data System (ADS)

    Zeiger, S. J.; Hubbart, J. A.

    2014-12-01

    Mixed-land use watersheds are often a complex patchwork of forested, agricultural, and urban land-uses where differential land-use mediated non-point source pollution can significantly impact water quality. Stream nitrogen and phosphorus concentrations serve as important variables for quantifying land use effects on non-point source pollution in receiving waters and relative impacts on aquatic biota. The Hinkson Creek Watershed (HCW) is a representative mixed land use urbanizing catchment (231 km2) located in central Missouri, USA. A nested-scale experimental watershed study including five permanent hydroclimate stations was established in 2009 to provide quantitative understanding of multiple land use impacts on nutrient loading. Spectrophotometric analysis was used to quantify total inorganic nitrogen (TIN) and total phosphorus (TP as PO4) regimes. Results (2010 - 2013) indicate average nitrate (NO3-) concentration (mg/l) range of 0.28 to 0.46 mg/l, nitrite (NO2-) range of 0.02 to 0.03 mg/l, ammonia (NH3) ranged from 0.04 to 0.08 mg/l, and TP range of 0.26 to 0.39 mg/l. With n=858, NO3-, NO2-, NH3, and TP concentrations were significantly (CI=95%, p=0.00) higher in the subbasin with the greatest percent cumulative agricultural land use (57%). NH3 and TP concentrations were significantly (CI=95%, p=0.00) higher (with the exception of the agricultural subbasin) in the subbasin with the greatest percent cumulative urban land use (26%). Results from multiple regression analyses showed percent cumulative agricultural and urban land uses accounted for 85% and 96% of the explained variance in TIN loading (CI=95%, p=0.08) and TP loading (CI=95%, p=0.02), respectively, between gauging sites. These results improve understanding of agricultural and urban land use impacts on nutrient concentrations in mixed use watersheds of the Midwest and have implications for nutrient reduction programs in the Mississippi River Basin and hypoxia reductions in the Gulf of Mexico, USA.

  4. Satellite-Based Spatiotemporal Trends in PM2.5 Concentrations: China 2004-2013

    NASA Technical Reports Server (NTRS)

    Ma, Zongwei; Hu, Xuefei; Sayer, Andrew M.; Levy, Robert; Zhang, Qiang; Xue, Yingang; Tong, Shilu; Bi, Jun; Huang, Lei; Liu, Yang

    2016-01-01

    Three decades of rapid economic development is causing severe and widespread PM2.5(particulate matter (is) less than 2.5 ) pollution in China. However, research on the health impacts of PM2.5 exposure has been hindered by limited historical PM2.5 concentration data. We estimated ambient PM2.5 concentrations from 2004 to 2013 in China at 0.1 deg resolution using the most recent satellite data and evaluated model performance with available ground observations. We developed a two-stage spatial statistical model using the Moderate Resolution Imaging Spectroradiometer (MODIS) Collection 6 aerosol optical depth (AOD) and assimilated meteorology, land use data, and PM2.5 concentrations from China's recently established ground monitoring network. An inverse variance weighting (IVW) approach was developed to combine MODIS Dark Target and Deep Blue AOD to optimize data coverage. We evaluated model predicted PM2.5 concentrations from 2004 to early 2014 using ground observations. The overall model cross-validation R(sup 2) and relative prediction error were 0.79 and 35.6%, respectively. Validation beyond the model year (2013) indicated that it accurately predicted PM(sub 2.5) concentrations with little bias at the monthly (R(sup 2) = 0.73), regression slope = 0.91) and seasonal (R(sup 2) = 0.79), regression slope = 0.92) levels. Seasonal variations revealed that winter was the most polluted season and that summer was the cleanest season. Analysis of predicted PM2.5 levels showed a mean annual increase of 1.97 micro-g/cu cm between 2004 and 2007 and a decrease of 0.46 micro-g/cu cm between 2008 and 2013. Our satellite-driven model can provide reliable historical PM2.5 estimates in China at a resolution comparable to those used in epidemiologic studies on the health effects of long-term PM2.5 exposure in North America. This data source can potentially advance research on PM2.5 health effects in China.

  5. Trends in mercury concentrations in the hair of women of Nome, Alaska - Evidence of seafood consumption or abiotic absorption?

    SciTech Connect

    Lasorsa, B.

    1992-06-01

    Eighty samples of hair from women of child-bearing age from Nome, Alaska, and seven control samples from women living in Sequim, Washington, were analyzed for mercury concentration by segmental analysis in an effort to determine whether seasonal fluctuations in mercury concentration in the hair samples can be correlated to seasonal seafood consumption. Full-length hair strands were analyzed in 1.1-cm segments representing 1 month`s growth using a strong acid digestion and cold vapor atomic fluorescence analysis. It was assumed that the concentration of mercury in each segment is an indicator of the mercury body burden during the month in which the segment emerged from the scalp. Eighteen of the samples show seasonal variability, with five of the controls and one Nome resident showing winter highs while all Nome residents show summer highs. Twenty-six of the samples show an increase in mercury concentration toward the distal end of the strand regardless of month of growth. The trend of increasing mercury concentrations toward the distal end of the hair strand regardless of month of emergence, and the documented presence of elevated levels of elemental mercury in the Nome area suggest that these elevated levels may actually be due to external contamination of the hair strands by adsorption and not due to ingestion of contaminated foodstuffs such as seafood.

  6. Trends in mercury concentrations in the hair of women of Nome, Alaska - Evidence of seafood consumption or abiotic absorption

    SciTech Connect

    Lasorsa, B. )

    1992-06-01

    Eighty samples of hair from women of child-bearing age from Nome, Alaska, and seven control samples from women living in Sequim, Washington, were analyzed for mercury concentration by segmental analysis in an effort to determine whether seasonal fluctuations in mercury concentration in the hair samples can be correlated to seasonal seafood consumption. Full-length hair strands were analyzed in 1.1-cm segments representing 1 month's growth using a strong acid digestion and cold vapor atomic fluorescence analysis. It was assumed that the concentration of mercury in each segment is an indicator of the mercury body burden during the month in which the segment emerged from the scalp. Eighteen of the samples show seasonal variability, with five of the controls and one Nome resident showing winter highs while all Nome residents show summer highs. Twenty-six of the samples show an increase in mercury concentration toward the distal end of the strand regardless of month of growth. The trend of increasing mercury concentrations toward the distal end of the hair strand regardless of month of emergence, and the documented presence of elevated levels of elemental mercury in the Nome area suggest that these elevated levels may actually be due to external contamination of the hair strands by adsorption and not due to ingestion of contaminated foodstuffs such as seafood.

  7. Trends In Nutrient and Sediment Concentrations and Loads In Major River Basins of the South-Central United States, 1993-2004

    USGS Publications Warehouse

    Rebich, Richard A.; Demcheck, Dennis K.

    2008-01-01

    Nutrient and sediment data collected at 115 sites by Federal and State agencies from 1993 to 2004 were analyzed by the U.S. Geological Survey to determine trends in concentrations and loads for selected rivers and streams that drain into the northwestern Gulf of Mexico from the south-central United States, specifically from the Lower Mississippi, Arkansas-White-Red, and Texas-Gulf Basins. Trends observed in the study area were compared to determine potential regional patterns and to determine cause-effect relations with trends in hydrologic and human-induced factors such as nutrient sources, streamflow, and implementation of best management practices. Secondary objectives included calculation of loads and yields for the study period as a basis for comparing the delivery of nutrients and sediment to the northwestern Gulf of Mexico from the various rivers within the study area. In addition, loads were assessed at seven selected sites for the period 1980-2004 to give hydrologic perspective to trends in loads observed during 1993-2004. Most study sites (about 64 percent) either had no trends or decreasing trends in streamflow during the study period. The regional pattern of decreasing trends in streamflow during the study period appeared to correspond to moist conditions at the beginning of the study period and the influence of three drought periods during the study period, of which the most extreme was in 2000. Trend tests were completed for ammonia at 49 sites, for nitrite plus nitrate at 69 sites, and for total nitrogen at 41 sites. For all nitrogen constituents analyzed, no trends were observed at half or more of the sites. No regional trend patterns could be confirmed because there was poor spatial representation of the trend sites. Decreasing trends in flow-adjusted concentrations of ammonia were observed at 25 sites. No increasing trends in concentrations of ammonia were noted at any sites. Flow-adjusted concentrations of nitrite plus nitrate decreased at 7

  8. Influence of wildfires on the variability and trend of ozone concentrations in the U.S. Intermountain West

    NASA Astrophysics Data System (ADS)

    Lu, Xiao; Zhang, Lin; Zhao, Yuanhong; Yue, Xu

    2016-04-01

    Wildfires are important sources of ozone by emitting large amounts of NOx and NMVOC, main ozone precursors at both global and regional scales. Their influences on ozone in the U.S. Intermountain West have recently received much interest because surface ozone concentrations over that region showed an increasing trend in the past two decades likely due to increasing wildfire emissions in a warming climate. Here we use the Lagrangian particle dispersion model (FLEXPART) as well as the GEOS-Chem chemical transport model to estimate wildfires' contribution on summer (June, July and August; JJA) ozone concentration variations, trends, and extremely high ozone events over the US Intermountain West for the past 22 years (1989-2010). We combine the resident time estimated from the FLEXPART 5-day backward trajectories and a high-resolution fire inventory to define a fire index representing the impact of wildfires on ozone concentration at a particular site for each day of summers 1989-2010. Over 26,000 FLEXPART back-trajectories are conducted for the whole time period and for 13 CASTNet surface monitoring sites. We build a stepwise multiple linear regression (SMLR) model of daily ozone concentrations using fire index and other meteorological variables for each site. The SMLR models explain 53% of the ozone variations (ranging from 12% to 68% for each site). We show that ozone produced from wildfires (calculated from SMLR model) are of high variability at daily scale (ranging from 0.1 ppbv to 20.7 ppbv), but are averaged to lower values of about 0.25-3.5 ppbv for summer mean. We estimate that wildfires magnify inter-annual variations of the regional mean summer ozone for about 32%, compared to the result with wildfires impact excluded from the SMLR model. Wildfire ozone enhancements increase at a rate of 0.04 ppbv per year, accouting for about 20% of the regional summer ozone trend during 1989-2010. Removing wildfires' impact would reduce 35% (46%) of the high-ozone days with

  9. Evaluating Trends in Historical PM2.5 Element Concentrations by Reanalyzing a 15-Year Sample Archive

    NASA Astrophysics Data System (ADS)

    Hyslop, N. P.; White, W. H.; Trzepla, K.

    2014-12-01

    The IMPROVE (Interagency Monitoring of PROtected Visual Environments) network monitors aerosol concentrations at 170 remote sites throughout the United States. Twenty-four-hour filter samples of particulate matter are collected every third day and analyzed for chemical composition. About 30 of the sites have operated continuously since 1988, and the sustained data record (http://views.cira.colostate.edu/web/) offers a unique window on regional aerosol trends. All elemental analyses have been performed by Crocker Nuclear Laboratory at the University of California in Davis, and sample filters collected since 1995 are archived on campus. The suite of reported elements has remained constant, but the analytical methods employed for their determination have evolved. For example, the elements Na - Mn were determined by PIXE until November 2001, then by XRF analysis in a He-flushed atmosphere through 2004, and by XRF analysis in vacuum since January 2005. In addition to these fundamental changes, incompletely-documented operational factors such as detector performance and calibration details have introduced variations in the measurements. Because the past analytical methods were non-destructive, the archived filters can be re-analyzed with the current analytical systems and protocols. The 15-year sample archives from Great Smoky Mountains (GRSM), Mount Rainier (MORA), and Point Reyes National Parks (PORE) were selected for reanalysis. The agreement between the new analyses and original determinations varies with element and analytical era. The graph below compares the trend estimates for all the elements measured by IMPROVE based on the original and repeat analyses; the elements identified in color are measured above the detection limit more than 90% of the time. The trend estimates are sensitive to the treatment of non-detect data. The original and reanalysis trends are indistinguishable (have overlapping confidence intervals) for most of the well-detected elements.

  10. Trend and concentration characteristics of precipitation and related climatic teleconnections from 1982 to 2010 in the Beas River basin, India

    NASA Astrophysics Data System (ADS)

    Yin, Yixing; Xu, Chong-Yu; Chen, Haishan; Li, Lu; Xu, Hongliang; Li, Hong; Jain, Sharad K.

    2016-10-01

    The Beas River, located in the Western Himalayan mountainous regions in India, is one of the major tributaries of the Indus River. However, recent changes of precipitation and related climatic teleconnections in this river basin have rarely been investigated yet. In this study, the trend and concentration characteristics of precipitation during1982-2010 are investigated by using Mann-Kendall trend test and two kinds of concentration indices. The climatic teleconnections are explored with the help of cross correlation, wavelet transform and composite analysis, revealing the relationship of precipitation with climatic indices of Indian summer monsoon (ISM), El Nino/Southern Oscillation (ENSO), Indian Ocean Dipole (IOD) and North Atlantic Oscillation (NAO). The results indicate that: (1) Precipitation of most of the stations increased in the monsoon season while precipitation of all the stations decreased in the non-monsoon seasons. As a result, the annual precipitation of the majority of the stations was on the decrease. (2) A general increase in the precipitation Gini coefficient and precipitation concentration degree (PCD) was detected. Moreover, the precipitation concentration period (PCP) is mainly within the period from May to August, and more PCP occurred in the monsoon months recently. (3) The relationship between monsoon precipitation and ISM is not significant in the Beas River basin. The relationship between precipitation and ENSO in winter is less significant than in the monsoon season, and the relationship of monsoon/winter precipitation with IOD is not as evident as that with ENSO. Besides, ENSO and NAO play important roles in the changes of monsoon and winter precipitation in the Beas River basin.

  11. Do PCB concentration trends in Lake Michigan fishes reflect global or local patterns?

    SciTech Connect

    Stow, C.A.; Carpenter, S.R.

    1994-12-31

    The authors have examined the fit of three alternative, models to PCB concentration data for seven species of Lake Michigan fishes. The best fit model for all seven species indicates that, following rapid decreases through the mid-1980s, PCBs are no longer declining. The authors believe this pattern indicates PCBs are currently originating from global or local pools that are being recycled in the environment. If the current PCB source in Lake Michigan is primarily sediment or fluvial, then this may be an isolated pattern. However, a sizeable atmospheric input would suggest that this problem may be occurring in many systems.

  12. Daily concentrations trend and change point of particulate matter (PM10) in Pahang, Malaysia - A case study at Balok Baru

    NASA Astrophysics Data System (ADS)

    Wahid, Sharifah Norhuda Syed; Ujang, Suriyati

    2015-02-01

    Daily concentration of particulate matter with aerodynamic diameter less than 10 μm (PM10) could be very harmful to human health such as respiratory and cardiovascular diseases. The purpose of this paper is to describe on the experiences of air pollutants in the state of Pahang, Malaysia during the first quarter of year 2014. Data were gathered from available automatic air quality monitoring stations at Balok Baru, Pahang through the assistance from the Department of Environment. Cumulative sum technique shows that a change occurred at March, 8th with 88 μg/ m3, moderate air quality level. This change point indicated that the PM10 level started to have a potential in moderate or worse level. In addition, time series regression analysis shows that the trend of daily concentrations of Balok Baru station was an upward trend and for additional day, the PM10 level was increased by 0.1117 μg/ m3. It is hoped that this study will give a significant contribution for future researcher in the area of the study on the risk of PM10 or other types of air pollutant to air quality and also human health.

  13. Diurnal trends in methylmercury concentration in a wetland adjacent to Great Salt Lake, Utah, USA

    USGS Publications Warehouse

    Naftz, D.L.; Cederberg, J.R.; Krabbenhoft, D.P.; Beisner, K.R.; Whitehead, J.; Gardberg, J.

    2011-01-01

    A 24-h field experiment was conducted during July 2008 at a wetland on the eastern shore of Great Salt Lake (GSL) to assess the diurnal cycling of methylmercury (MeHg). Dissolved (<0.45??m) MeHg showed a strong diurnal variation with consistently decreasing concentrations during daylight periods and increasing concentrations during non-daylight periods. The proportion of MeHg relative to total Hg in the water column consistently decreased with increasing sunlight duration, indicative of photodegradation. During the field experiment, measured MeHg photodegradation rates ranged from 0.02 to 0.06ngL-1h-1. Convective overturn of the water column driven by nighttime cooling of the water surface was hypothesized as the likely mechanism to replace the MeHg in the water column lost via photodegradation processes. A hydrodynamic model of the wetland successfully simulated convective overturn of the water column during the field experiment. Study results indicate that daytime monitoring of selected wetlands surrounding GSL may significantly underestimate the MeHg content in the water column. Wetland managers should consider practices that maximize the photodegradation of MeHg during daylight periods. ?? 2011.

  14. Sources and preparation of data for assessing trends in concentrations of pesticides in streams of the United States, 1992–2010

    USGS Publications Warehouse

    Martin, Jeffrey D.; Eberle, Michael; Nakagaki, Naomi

    2011-01-01

    This report updates a previously published water-quality dataset of 44 commonly used pesticides and 8 pesticide degradates suitable for a national assessment of trends in pesticide concentrations in streams of the United States. Water-quality samples collected from January 1992 through September 2010 at stream-water sites of the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Program and the National Stream Quality Accounting Network (NASQAN) were compiled, reviewed, selected, and prepared for trend analysis. The principal steps in data review for trend analysis were to (1) identify analytical schedule, (2) verify sample-level coding, (3) exclude inappropriate samples or results, (4) review pesticide detections per sample, (5) review high pesticide concentrations, and (6) review the spatial and temporal extent of NAWQA pesticide data and selection of analytical methods for trend analysis. The principal steps in data preparation for trend analysis were to (1) select stream-water sites for trend analysis, (2) round concentrations to a consistent level of precision for the concentration range, (3) identify routine reporting levels used to report nondetections unaffected by matrix interference, (4) reassign the concentration value for routine nondetections to the maximum value of the long-term method detection level (maxLT-MDL), (5) adjust concentrations to compensate for temporal changes in bias of recovery of the gas chromatography/mass spectrometry (GCMS) analytical method, and (6) identify samples considered inappropriate for trend analysis. Samples analyzed at the USGS National Water Quality Laboratory (NWQL) by the GCMS analytical method were the most extensive in time and space and, consequently, were selected for trend analysis. Stream-water sites with 3 or more water years of data with six or more samples per year were selected for pesticide trend analysis. The selection criteria described in the report produced a dataset of 21

  15. Insights into PBDE Uptake, Body Burden, and Elimination Gained from Australian Age–Concentration Trends Observed Shortly after Peak Exposure

    PubMed Central

    Gyalpo, Tenzing; Toms, Leisa-Maree; Mueller, Jochen F.; Harden, Fiona A.; Hungerbühler, Konrad

    2015-01-01

    Background Population pharmacokinetic models combined with multiple sets of age–concentration biomonitoring data facilitate back-calculation of chemical uptake rates from biomonitoring data. Objectives We back-calculated uptake rates of PBDEs for the Australian population from multiple biomonitoring surveys (top-down) and compared them with uptake rates calculated from dietary intake estimates of PBDEs and PBDE concentrations in dust (bottom-up). Methods Using three sets of PBDE elimination half-lives, we applied a population pharmacokinetic model to the PBDE biomonitoring data measured between 2002–2003 and 2010–2011 to derive the top-down uptake rates of four key PBDE congeners and six age groups. For the bottom-up approach, we used PBDE concentrations measured around 2005. Results Top-down uptake rates of Σ4BDE (the sum of BDEs 47, 99, 100, and 153) varied from 7.9 to 19 ng/kg/day for toddlers and from 1.2 to 3.0 ng/kg/day for adults; in most cases, they were—for all age groups—higher than the bottom-up uptake rates. The discrepancy was largest for toddlers with factors up to 7–15 depending on the congener. Despite different elimination half-lives of the four congeners, the age–concentration trends showed no increase in concentration with age and were similar for all congeners. Conclusions In the bottom-up approach, PBDE uptake is underestimated; currently known pathways are not sufficient to explain measured PBDE concentrations, especially in young children. Although PBDE exposure of toddlers has declined in the past years, pre- and postnatal exposure to PBDEs has remained almost constant because the mothers’ PBDE body burden has not yet decreased substantially. Citation Gyalpo T, Toms LM, Mueller JF, Harden FA, Scheringer M, Hungerbühler K. 2015. Insights into PBDE uptake, body burden, and elimination gained from Australian age–concentration trends observed shortly after peak exposure. Environ Health Perspect 123:978–984;

  16. Trends and variability in blood lead concentrations among US children and adolescents.

    PubMed

    Jain, Ram B

    2016-04-01

    Using data from the National Health and Nutrition Examination Survey for the period 2003-2012, the objective of this study was to evaluate trends in blood lead levels (BLL) among children aged 1-5 and 6-11 years and smoker and nonsmoker adolescents aged 12-19 years. Regression models with log10 transformed values of BLLs as dependent variable were fitted to evaluate how gender, race/ethnicity, smoking, and exposure to secondhand smoke at home affect BLLs. Irrespective of age, gender, and race/ethnicity, BLLs declined over the study period (p ≤ 0.01). Overall, adjusted BLLs declined by 0.00114 μg/dL for every 2 years. Children aged 1-5 years had about 50 % higher BLLs than smoker adolescents, about 75 % higher BLLs than nonsmoker adolescents, and about 45 % higher BLLs than children aged 6-11 years. While overall, children aged 1-5 years with BLL ≥ 5 μg/dL made up 3.24 %, 7.8 % non-Hispanic Black children aged 1-5 years had BLL ≥ 5 μg/dL. Males were found to have higher adjusted BLLs than females, and non-Hispanic Blacks were found to have higher adjusted BLLs than non-Hispanic Whites. Higher poverty income ratio was associated with lower adjusted BLLs (β = -0.02916, p < 0.01). Children living in owner-occupied homes had lower adjusted BLLs than children living in renter-occupied homes. BLLs increased with increase in number of smokers smoking inside the home (β = 0.02496, p = 0.02). In conclusion, while BLLs have declined for all age groups, genders, and races/ethnicities, certain races/ethnicities like non-Hispanic Blacks continue to have substantially higher BLLs than non-Hispanic Whites. PMID:26758308

  17. Regional trends in soil acidification and exchangeable metal concentrations in relation to acid deposition rates.

    PubMed

    Stevens, Carly J; Dise, Nancy B; Gowing, David J

    2009-01-01

    The deposition of high levels of reactive nitrogen (N) and sulphur (S), or the legacy of that deposition, remain among the world's most important environmental problems. Although regional impacts of acid deposition in aquatic ecosystems have been well documented, quantitative evidence of wide-scale impacts on terrestrial ecosystems is not common. In this study we analysed surface and subsoil chemistry of 68 acid grassland sites across the UK along a gradient of acid deposition, and statistically related the concentrations of exchangeable soil metals (1 M KCl extraction) to a range of potential drivers. The deposition of N, S or acid deposition was the primary correlate for 8 of 13 exchangeable metals measured in the topsoil and 5 of 14 exchangeable metals in the subsoil. In particular, exchangeable aluminium and lead both show increased levels above a soil pH threshold of about 4.5, strongly related to the deposition flux of acid compounds.

  18. Trends in 2,3,7,8-TCDD concentrations in fish tissues downstream of pulp mills bleaching with chlorine

    SciTech Connect

    Abbott, J.D.; Hinton, S.W.

    1996-07-01

    Field measurements of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) concentrations in fish tissues from riverine environments impacted by treated pulp and paper industry effluent in the US were analyzed. Data from 39 sites in 14 states across the four major US paper-making regions were assembled and analyzed to determine the annual change in lipid-normalized concentrations of TCDD in fish tissue. The results provide strong evidence of a nationwide trend of decreasing lipid-normalized TCDD concentrations in fish tissue, with 84% of the examined sites showing a decrease. While the paucity of data currently limits any conclusions regarding the statistical significance at individual sites, the overall median rate calculated indicates a 0.36 annual fractional decrease in lipid-normalized concentrations of TCDD in fish tissue (0.18 to 0.51, 95% confidence interval); the average annual fractional decrease was 0.35 (0.23 to 0.47, 95% confidence interval). Subdividing fish into benthic and nonbenthic categories resulted in rates which were not significantly different from one another for both the median and mean statistics.

  19. Report on concentrations, lifetimes, and trends of CFCs, halons, and related species

    NASA Technical Reports Server (NTRS)

    Kaye, J. A. (Editor); Penkett, S. A. (Editor); Ormond, F. M. (Editor); Fraser, P.; Fisher, D.; Bloomfield, P.; Sander, S. P.; Ko, M. K. W.

    1994-01-01

    The atmospheric lifetimes of molecules containing chlorine and bromine are the dominant parameters influencing their ability to promote enhanced ozone destruction in the stratosphere. The purpose of this report is to assess the present state of knowledge of the lifetimes of halocarbons using two complementary approaches. First, a time series of measurements of gas concentrations is used together with information on their emissions histories and a computational model of atmospheric circulation and chemistry to infer lifetimes through a mass balance approach. Second, an atmospheric chemical-dynamical model is used with detailed information on the chemistry and spectroscopy of the molecules of interest to calculate lifetimes. The lifetimes determined by these two methods are then compared. Attention is focused most closely on fully halogenated chlorine- and bromine-containing molecules, primarily the chlorofluorocarbons, and the halons, because of their ability to deliver chlorine and bromine to the stratosphere. Some attention will be given to those molecules containing hydrogen, which are subject to removal in the troposphere primarily by reaction with OH and by other processes.

  20. Correlation of indoor radon concentration to commonly available geologic data

    NASA Astrophysics Data System (ADS)

    Burkhart, James F.; Huber, Thomas P.

    1993-03-01

    Over the last several years, the inhalation of decay products coming from radon-222 has become a national health concern. It is estimated that somewhere between 16,000 and 20,000 people die annually in the United States from lung cancer due to exposure to these decay products. Nationwide, 95% of all homes have not been tested for radon, and so it would seem that any methodology that could give a general idea of indoor radon concentrations (without actually testing the house itself) might be useful. While not intended to replace a radon test, which is both simple and inexpensive, our project attempts to predict indoor radon concentrations based on easily obtainable information from Soil Conservation Service county soil surveys and US Geological Survey surficial geology maps. We have chosen four parameters: soil permeability, surficial geology, soil shrink-swell potential, and distance to the nearest geologic fault. Of these four variables, surficial geology and distance to fault correlated well to winter indoor radon concentrations as measured by short-term (48-h) tests. While it is understood that there are limits to this methodology, primarily because of map scale problems, the correlations mentioned above were very strong and suggest further study would be useful.

  1. FRIT DEVELOPMENT FOR HIGH LEVEL WASTE SLUDGE BATCH 5: COMPOSITIONAL TRENDS FOR VARYING ALUMINUM CONCENTRATIONS

    SciTech Connect

    Fox, K; Tommy Edwards; David Best; Irene Reamer; Phyllis Workman

    2008-08-28

    The objective of this study was to experimentally measure the properties and performance of a series of glasses with compositions that could represent Sludge Batch 5 (SB5) as processed at the Defense Waste Processing Facility (DWPF). The data was used to provide recommendations to the Liquid Waste Organization (LWO) regarding blending and washing strategies in preparing SB5 based on acceptability of the glass compositions. These data were also used to guide frit optimization efforts as the SB5 composition was finalized. Glass compositions for this study were developed by combining a series of SB5 composition projections with a group of frits. Three composition projections for SB5 were developed using a model-based approach at Savannah River National Laboratory (SRNL). These compositions, referred to as SB5 Cases B, C and D, projected removal of 25, 50 and 75% (respectively) of the aluminum in Tank 51 through the low temperature aluminum dissolution process. The frits for this study (Frits 530 through 537) were selected based on their predicted operating windows (i.e., ranges of waste loadings over which the predicted properties of the glasses were acceptable) and their potential (based on historical trends) to provide acceptable melt rates for SB5. Six additional glasses were designed to evaluate alternatives for uranium in DWPF-type glasses used for variability studies and some scoping studies. Since special measures are necessary when working with uranium-containing glasses in the laboratory, it is desirable as a cost and time saving measure to find an alternative for uranium to support frit optimization efforts. Hafnium and neodymium were investigated as potential surrogates for uranium, and other glasses were made by simply excluding the radioactive components and renormalizing the glass composition. The study glasses were fabricated and characterized at SRNL. Chemical composition analyses suggested only minor difficulties in meeting the targeted compositions

  2. Concentrations and trends of perfluorinated chemicals in potential indoor sources from 2007 through 2011 in the US.

    PubMed

    Liu, Xiaoyu; Guo, Zhishi; Krebs, Kenneth A; Pope, Robert H; Roache, Nancy F

    2014-03-01

    Certain perfluorinated chemicals (PFCs) in consumer products used indoors are potential indoor PFCs sources and have been associated with developmental toxicity and other adverse health effects in laboratory animals (Lao et al., 2007). The concentrations of selected PFCs including perfluorooctanoic acid (PFOA) and other perfluorocarboxylic acids (PFCAs), in 35 selected consumer products that are commonly used in indoors were measured from the year of 2007 through 2011. The products collected included carpet, commercial carpet-care liquids, household carpet/fabric-care liquids, treated apparel, treated home textiles, treated non-woven medical garments, floor waxes, food-contact paper, membranes for apparel, and thread-sealant tapes. They were purchased from retail outlets in the United States between March 2007 and September 2011. The perfluorocarboxylic acid (PFCA) contents in the products have shown an overall downward trend. However, PFOA (C8) could still be detected in many products that we analyzed. Reductions of PFCAs were shown in both short-chain PFCAs (sum of C4 to C7) and long-chain PFCAs (sum of C8 to C12) over the study period. There were no significant changes observed between short-chain PFCAs and long-chain PFCAs. Fourteen products were analyzed to determine the amounts of perfluoroalkyl sulfonates (PFASs) they contained. These limited data show the pronounced increase of perfluoro-butane sulfonate (PFBS), an alternative to perfluorooctanoic sulfonate (PFOS), in the samples. A longer and wider range of study will be required to confirm this observed trend. PMID:24268172

  3. Concentration trends and bioavailability of chlorinated dioxins to crabs from B.C. pulp mills and harbours

    SciTech Connect

    Yunker, M.B.; Cretney, W.J.

    1995-12-31

    Since 1990 approximately 100 synchronous samples of sediment and Dungeness crab (Cancer magister) hepatopancreas have been collected from B.C. harbours and pulp mill sites and analyzed for chlorinated dibenzo-p-dioxin and dibenzofuran congeners. Mean sediment/crab bioconcentration factors (BSAFs) for both dioxins and furans decrease uniformly from approximately log 0.5 for the tetrachloro congeners to log {minus}2 for the octachloro congeners. Individual pairs of samples vary, but no systematic trends are apparent either over time or between mill sites or depositional environments. Differences in dioxin and furan sources that are apparent as principal components analysis (PCA) class separations in both the sediment and crab data sets also are not reflected in differences in BSAFS. Partial least squares (PLS) path modeling reveals little correspondence in congener patterns between sediments and crabs and rules out a direct pathway for contaminant transfer. Results suggest some food chain bioaccumulation for the tetra and pentachloro congeners, but bioavailability to the crabs decreases from the penta to octachloro congeners, Concentration trends over time for both sediment and crabs from the mill sites suggest that the mill-related dioxin and furans are preferentially associated with a suspended particulate or near-bottom nepheloid fraction that is easily buried over time in quiescent areas (e.g., fjords), but has remained available for accumulation in locations that are well flushed by tidal action.

  4. Trends in chloride, dissolved-solids, and nitrate concentrations in ground water, Carson Valley and Topaz Lake Areas, Douglas County, Nevada, 1959-88

    USGS Publications Warehouse

    Thodal, C.E.

    1996-01-01

    Rapid population growth in Douglas County, an area of approximately 750 square miles in west-central Nevada, has led to concern about the present and future effects of development on ground water. This report describes the results of two nonparametric statistical procedures applied to detect trends in concentrations of chloride, dissolved solids, and nitrate in ground water. The water-quality data consist of analytical results from ground-water samples collected and analyzed by the U. S. Geological Survey and ground-water-quality data provided by the Nevada Bureau of Health Protection Services for the Carson Valley and Topaz Lake areas of Douglas County, Nevada. For purposes of this study, statistical significance, expressed as the p-value, was set at 0.1. The Mann-Whitney-Wilcoxan rank-sum test detected increasing step-trends for nitrate in one of seven residential areas and for dissolved-solids concentrations throughout the study area. Decreasing step-trends for chloride and dissolved-solids concentrations were detected in the west Carson Valley area. Kendall's Tau detected monotonic trends for increasing nitrate concentrations at four domestic wells and for increasing dissolved-solids concentrations at two domestic wells. No other statistically significant trends were indicated by either test. Land-use relations to areas where increasing trends were detected suggest that the density of individual wastewater-treatment systems may exceed the capacity of soils to treat wastewater leachate.

  5. Use of satellite-based aerosol optical depth and spatial clustering for PM2.5 prediction and concentration trends in the New England region, U.S

    NASA Astrophysics Data System (ADS)

    Lee, H.; Coull, B. A.; Bell, M. L.; Kang, C.; Koutrakis, P.

    2012-12-01

    The efficacy of air pollution emission control policies can be evaluated by investigating the concentration trends of ambient air pollutants. Satellite-based PM2.5 monitoring has the potential to complement the ground monitoring networks, especially for regions with sparsely distributed monitors. In our study, we predicted daily ambient PM2.5 concentrations using Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol optical depth (AOD) and spatial clustering and subsequently examined the PM2.5 concentration trends in the New England region, U.S. for the period 2000-2008. The daily calibration of MODIS AOD data using ground PM2.5 measurements in the mixed effects model rendered AOD a robust predictor of ground PM2.5 concentrations. Also the spatial clustering made it possible to estimate PM2.5 concentrations when AOD values were not available (i.e., non-retrieval days). Overall, we predicted daily surface PM2.5 concentrations (including both retrieval and non-retrieval days) with reasonably high R2 (0.83) and low percent mean relative error (3.5%). Based on the daily predicted PM2.5 concentrations, we found higher concentration decreases in urban areas than in rural ones and the highest and lowest decreases during the winter and the summer, respectively. These concentration trends provide evidence that primary particle concentrations decreased more relative to secondary particle ones during the study period. This is also supported by ground speciation data which showed stronger downward concentration trend of primary pollutants including black carbon (BC; -4.5% per year) compared to that of secondary ones including sulfate (SO42-, -2.4% per year). The satellite-based approach of examining spatial patterns of concentration trends, in combination with ground PM2.5 speciation data, can be of tremendous regulatory importance.

  6. Decreasing trends of suspended particulate matter and PM2.5 concentrations in Tokyo, 1990-2010.

    PubMed

    Hara, Kunio; Homma, Junichi; Tamura, Kenji; Inoue, Mariko; Karita, Kanae; Yano, Eiji

    2013-06-01

    In Tokyo, the annual average suspended particulate matter (SPM) and PM2.5 concentrations have decreased in the past two decades. The present study quantitatively evaluated these decreasing trends using data from air-pollution monitoring stations. Annual SPM and PM2.5 levels at 83 monitoring stations and hourly SPM and PM2.5 levels at four monitoring stations in Tokyo, operated by the Tokyo Metropolitan Government, were used for analysis, together with levels of co-pollutants and meteorological conditions. Traffic volume in Tokyo was calculated from the total traveling distance of vehicles as reported by the Ministry of Land, Infrastructure, Transport, and Tourism. High positive correlations between SPM levels and nitrogen oxide levels, sulfur dioxide levels, and traffic volume were determined. The annual average SPM concentration declined by 62.6%from 59.4 microg/m3 in 1994 to 22.2 microg/m3 in 2010, and PM2.5 concentration also declined by 49.8% from 29.3 microg/m3 in 2001 to 14.7 microg/m3 in 2010. Likewise, the frequencies of hourly average SPM and PM2.5 concentrations exceeding the daily guideline values have significantly decreased since 2001 and the hourly average SPM or PM2.5 concentrations per traffic volume for each time period have also significantly decreased since 2001. However SPM and PM2.5 concentrations increased at some monitoring stations between 2004 and 2006 and from 2009 despite strengthened environmental regulations and improvements in vehicle engine performance. The annual average SPM and PM2.5 concentrations were positively correlated with traffic volumes and in particular with the volume of diesel trucks. These results suggest that the decreasing levels of SPM and PM2.5 in Tokyo may be attributable to decreased traffic volumes, along with the effects of stricter governmental regulation and improvements to vehicle engine performance, including the fitting of devices for exhaust emission reduction. PMID:23858999

  7. Decreasing trends of suspended particulate matter and PM2.5 concentrations in Tokyo, 1990-2010.

    PubMed

    Hara, Kunio; Homma, Junichi; Tamura, Kenji; Inoue, Mariko; Karita, Kanae; Yano, Eiji

    2013-06-01

    In Tokyo, the annual average suspended particulate matter (SPM) and PM2.5 concentrations have decreased in the past two decades. The present study quantitatively evaluated these decreasing trends using data from air-pollution monitoring stations. Annual SPM and PM2.5 levels at 83 monitoring stations and hourly SPM and PM2.5 levels at four monitoring stations in Tokyo, operated by the Tokyo Metropolitan Government, were used for analysis, together with levels of co-pollutants and meteorological conditions. Traffic volume in Tokyo was calculated from the total traveling distance of vehicles as reported by the Ministry of Land, Infrastructure, Transport, and Tourism. High positive correlations between SPM levels and nitrogen oxide levels, sulfur dioxide levels, and traffic volume were determined. The annual average SPM concentration declined by 62.6%from 59.4 microg/m3 in 1994 to 22.2 microg/m3 in 2010, and PM2.5 concentration also declined by 49.8% from 29.3 microg/m3 in 2001 to 14.7 microg/m3 in 2010. Likewise, the frequencies of hourly average SPM and PM2.5 concentrations exceeding the daily guideline values have significantly decreased since 2001 and the hourly average SPM or PM2.5 concentrations per traffic volume for each time period have also significantly decreased since 2001. However SPM and PM2.5 concentrations increased at some monitoring stations between 2004 and 2006 and from 2009 despite strengthened environmental regulations and improvements in vehicle engine performance. The annual average SPM and PM2.5 concentrations were positively correlated with traffic volumes and in particular with the volume of diesel trucks. These results suggest that the decreasing levels of SPM and PM2.5 in Tokyo may be attributable to decreased traffic volumes, along with the effects of stricter governmental regulation and improvements to vehicle engine performance, including the fitting of devices for exhaust emission reduction.

  8. Ten-year trends in urinary concentrations of triclosan and benzophenone-3 in the general U.S. population from 2003 to 2012.

    PubMed

    Han, Changwoo; Lim, Youn-Hee; Hong, Yun-Chul

    2016-01-01

    Despite their popular use and emerging evidences of adverse health effects, consequent trends in population level triclosan and benzophenone-3 exposure have been poorly evaluated. Therefore, we examined temporal trends of urinary triclosan and benzophenone-3 concentration in the general U.S. population by combining five cycles of National Health and Nutritional Examination Survey (NHANES, 2003-2012) data. We calculated percent changes and the least square geometric means (LSGMs) of urinary triclosan and benzophenone-3 concentration from 10,232 participants by using multivariable regression models. As a result, LSGM concentration of urinary triclosan and benzophenone-3 did not show statistically significant changes over the study period. [Percent change (95% CI): Triclosan, -7.35% (-20.86, 8.47); Benzophenone-3, 7.08% (-27.88, 58.99)] However, we found decreasing trend of urinary triclosan concentration and increasing trend of urinary benzophenone-3 concentration since 2005-2006. Socio-demographic factors which affected urinary concentration of triclosan and benzophenone-3 persisted throughout 10 year study period. Highest income group showed higher level of urinary triclosan and benzophenone-3 concentration. Overall concentration of benzophenone-3 was higher in female than in male, and higher in non-Hispanic Whites than any other races/ethnicities.

  9. Concentrations, Trends, and Air-Water Exchange of PAHs and PBDEs Derived from Passive Samplers in Lake Superior in 2011.

    PubMed

    Ruge, Zoe; Muir, Derek; Helm, Paul; Lohmann, Rainer

    2015-12-01

    Polycyclic aromatic hydrocarbons (PAHs) and polybrominated diphenylethers (PBDEs) are both currently released into the environment from anthropogenic activity. Both are hence primarily associated with populated or industrial areas, although wildfires can be an important source of PAHs, as well. Polyethylene passive samplers (PEs) were simultaneously deployed in surface water and near surface atmosphere to determine spatial trends and air-water gaseous exchange of 21 PAHs and 11 PBDEs at 19 sites across Lake Superior in 2011. Surface water and atmospheric PAH concentrations were greatest at urban sites (up to 65 ng L(-1) and 140 ng m(-3), respectively, averaged from June to October). Near populated regions, PAHs displayed net air-to-water deposition, but were near equilibrium off-shore. Retene, probably depositing following major wildfires in the region, dominated dissolved PAH concentrations at most Lake Superior sites. Atmospheric and dissolved PBDEs were greatest near urban and populated sites (up to 6.8 pg L(-1) and 15 pg m(-3), respectively, averaged from June to October), dominated by BDE-47. At most coastal sites, there was net gaseous deposition of BDE-47, with less brominated congeners contributing to Sault Ste. Marie and eastern open lake fluxes. Conversely, the central open lake and Eagle Harbor sites generally displayed volatilization of PBDEs into the atmosphere, mainly BDE-47. PMID:26436513

  10. Spatial patterns and temporal trends in mercury concentrations, precipitation depths, and mercury wet deposition in the North American Great Lakes region, 2002-2008

    USGS Publications Warehouse

    Risch, Martin R.; Gay, David A.; Fowler, Kathleen K.; Keeler, Gerard J.; Backus, Sean M.; Blanchard, Pierrette; Barres, James A.; Dvonch, J. Timothy

    2012-01-01

    Annual and weekly mercury (Hg) concentrations, precipitation depths, and Hg wet deposition in the Great Lakes region were analyzed by using data from 5 monitoring networks in the USA and Canada for a 2002-2008 study period. High-resolution maps of calculated annual data, 7-year mean data, and net interannual change for the study period were prepared to assess spatial patterns. Areas with 7-year mean annual Hg concentrations higher than the 12 ng per liter water-quality criterion were mapped in 4 states. Temporal trends in measured weekly data were determined statistically. Monitoring sites with significant 7-year trends in weekly Hg wet deposition were spatially separated and were not sites with trends in weekly Hg concentration. During 2002-2008, Hg wet deposition was found to be unchanged in the Great Lakes region and its subregions. Any small decreases in Hg concentration apparently were offset by increases in precipitation.

  11. Radionuclide concentrations in streams in the upper Blackfoot River basin, southeastern Idaho

    USGS Publications Warehouse

    Low, Walton H.

    1981-01-01

    Data on radionuclide concentrations in water and sediment material in the phosphate-mining area of the upper Blackfoot River basin were collected from May to October 1979. Maximum measured uranium and radium-226 concentrations dissolved in water were 3.7 micrograms per liter and 1.8 picocuries per liter , respectively. Maximum measured uranium and radium-226 concentrations in stream-bottom material were 5.5 micrograms per gram and 1.8 picocuries per gram, respectively. Maximum measured uranium and radium-226 concentrations on bottom material were 9.9 micrograms per gram and 3.9 picocuries per gram, respectively, in sediment-retention ponds, and 17 micrograms per gram and 3.5 picocuries per gram, respectively, in a mine pit. Maximum observed radon-222 concentration was 120 picocuries per liter in surface water and averaged 550 picocuries per liter at Formation Springs (site 10). All radionuclide concentrations were within existing State and Federal water-quality standards. Radionuclide concentrations were not significantly increased downstream from active mining sites. (USGS)

  12. Source identification and trends in concentrations of gaseous and fine particulate principal species in Seoul, South Korea.

    PubMed

    Kang, Choong-Min; Kang, Byung-Wook; Lee, Hak Sung

    2006-07-01

    Ambient measurements were made using two sets of annular denuder system during the four seasons (April 2001 to February 2002) and were then compared with the results during the period of 1996-1997 to estimate the trends and seasonal variations in concentrations of gaseous and fine particulate matter (PM2.5) principal species. Annual averages of gaseous HNO3 and NH3 increased by 11% and 6%, respectively, compared with those of the previous study, whereas HONO and SO2 decreased by 11% and 136%, respectively. The PM2.5 concentration decreased by -17%, 35% for SO4(2-), and 29% for NH4+, whereas NO3- increased by 21%. Organic carbon (OC) and elemental carbon (EC) were 12.8 and 5.98 microg/m(-3), accounting for -26 and 12% of PM2.5 concentration, respectively. The species studied accounted for 84% of PM2.5 concentration, ranging from 76% in winter to 97% in summer. Potential source contribution function (PSCF) analysis was used to identify possible source areas affecting air pollution levels at a receptor site in Seoul. High possible source areas in concentrations of PM2.5, NO3-, SO4(2-), NH4+, and K+ were coastal cities of Liaoning province (possibly emissions from oil-fired boilers on ocean liners and fishing vessels and industrial emissions), inland areas of Heibei/Shandong provinces (the highest density areas of agricultural production and population) in China, and typical port cities (Mokpo, Yeosu, and Busan) of South Korea. In the PSCF map for OC, high possible source areas were also coastal cities of Liaoning province and inland areas of Heibei/Shandong provinces in China. In contrast, high possible source areas of EC were highlighted in the south of the Yellow Sea, indicating possible emissions from oil-fired boilers on large ships between South Korea and Southeast Asia. In summary, the PSCF results may suggest that air pollution levels in Seoul are affected considerably by long-range transport from external areas, such as the coastal zone in China and other

  13. Trends in lead concentrations in major U.S. rivers and their relation to historical changes in gasoline-lead consumption

    USGS Publications Warehouse

    Alexander, R.B.; Smith, R.A.

    1988-01-01

    Declines in concentrations of dissolved lead occurred at nearly two-thirds of 306 locations on major U.S. rivers from 1974 to 1985. Declines in dissolved lead concentrations are statistically significant (p < 0.10) at approximately one-third of the sampling locations. Statistically significant increases in dissolved lead concentrations occurred at only 6 percent of the sites, but are clustered in the Texas-Gulf and Lower Mississippi region. Possible explanations for the observed trends in lead concentrations are tested through comparisons with (1) records of lead discharges from major sources including leaded-gasoline consumption and municipal- and industrial-point source discharges, (2) trends in various water-quality constituents such as pH and total alkalinity, and (3) basin characteristics such as drainage area. Statistically significant declines in lead concentrations in streams and gasoline lead (i.e., the largest source of lead at these sites) are highly coincident for the 1979 to 1980 period at most sampling locations. The greatest amount of decline in gasoline lead occurred at sites showing statistically significant downtrends in stream concentrations of lead from 1974 to 1985. No more than 5 percent of the trends in stream lead are influenced by municipal- and industrial-point sources of lead. Factors that affect the transport of dissolved lead, including lead solubility, suspended sediment, and basin characteristics such as drainage basin size, are not significantly related to trends in dissolved lead. Trends in streamflow explain no more than 7 percent of the downtrends in concentrations of lead and may partly explain the frequent increases in lead concentrations in the Texas-Gulf and Lower Mississippi regions.Declines in concentrations of dissolved lead occurred at nearly two-thirds of 306 locations on major US rivers from 1974 to 1985. Declines in dissolved lead concentrations are statistically significant at approximately one-third of the sampling

  14. Long-term trends in atmospheric concentrations of sulfate, total sulfur, and trace elements in the northeastern United States

    NASA Astrophysics Data System (ADS)

    Husain, Liaquat; Parekh, Pravin P.; Dutkiewicz, Vincent A.; Khan, Adil R.; Yang, Karl; Swami, Kamal

    2004-09-01

    Concentrations of K, Sc, Mn, Fe, Zn, As, Se, Sb, Hg, and Pb were determined in quarterly composites of daily aerosol samples collected at Mayville, and 530 km downwind at Whiteface Mountain (1.5 km altitude), New York, for ˜20 years. SO4 concentrations [SO4] were determined in individual daily samples. Continuous hourly SO2 data are also available for much of the period. [SO4] at Mayville were twice that at Whiteface Mountain, and total S (S as SO2 + SO4) burden was fourfold higher at Mayville. From 1979 through 2002, [SO4] decreased by 59% at Whiteface Mountain, and at Mayville the decrease was 30% from 1984 to 2002. From 1979 to 2002, SO2 emissions in eight states upwind of and contiguous with New York State (Ohio, Pennsylvania, Indiana, Illinois, Wisconsin, Kentucky, West Virginia, and Ontario, Canada) decreased by 49%. A linear relationship was observed between atmospheric [SO4] and [total S] burden at the two sites with the cumulative SO2 emissions. These observations suggest that any further reductions in SO2 emissions would result in a proportional decrease in [SO4] and [total S] across New York State and possibly across the northeastern United States. The data at Whiteface Mountain suggest that beginning in 1997, the decrease in [SO4] and [total S], relative to SO2 emissions, may be faster than the earlier period. Like [SO4] and [total S], the trace element concentrations were twofold to fivefold higher at Mayville than at Whiteface Mountain. The concentrations at both sites showed an unmistakable decrease over time. The largest decreases were observed for Hg (16%/year at Whiteface Mountain and 10%/year at Mayville) and Pb (14%/year at Whiteface Mountain and 10%/year at Mayville). The remaining elements (except Sb), including the crustal elements K, Mn, Sc, and Fe, showed a decreases of 3-5%/year. Trends for Sb at Whiteface Mountain and for Mn at Mayville could not be accurately discerned, apparently due to some nearby emissions. Apparently, the reductions

  15. Controlling Factors of Long-Term Trends in Mercury Wet Deposition and Precipitation Concentrations at Huntington Wildlife Forest

    NASA Astrophysics Data System (ADS)

    Ye, Z.; Mao, H.; Driscoll, C. T.

    2015-12-01

    Observations from the Mercury Deposition Network (MDN) at Huntington Wildlife Forest (HWF) suggested that a significant decline (r2 = 0.34, p = 0.03) from 2000 to 2013 in volume weighted mean (VWM) Hg concentrations in precipitation was linked to Hg emission decreases in the United States, especially in the Northeast and Midwest, and yet Hg wet deposition has remained fairly constant over the past two decades. The present study aimed to investigate the climatic, terrestrial, and anthropogenic factors that influenced the decadal pattern in Hg wet deposition in upstate NY. In spring and summer, when Hg wet deposition was the strongest, significant positive correlation (r2 = 0.89, p < 0.0001 in spring; r2 = 0.58, p = 0.002 in summer) of Hg wet deposition with precipitation was found. Increases in precipitation during these seasons could offset the decreasing of Hg concentration in precipitation. Besides, springtime positive correlation (r2 = 0.35, p = 0.02) between precipitation and the North Atlantic Oscillation (NAO) index together with geopotential height and wind speed analysis indicated that large-scale dynamical forcing was likely an important factor influencing the long term trend in springtime Hg wet deposition at HWF. To further quantify the roles of meteorological and anthropogenic factors in Hg wet deposition, the Community Multiscale Air Quality (CMAQ) model was employed using an algorithm depicting state-of-the-art Hg chemistry mechanism and up-to-date Hg emission inventories evaluated with MDN and Atmospheric Mercury Network (AMNet) measurement data. CMAQ simulations with a constant vs. realistic meteorological conditions for multiple warm seasons (including spring and summer) were used to characterize and quantify the impacts of inter-annual variability of precipitation and atmospheric circulation on Hg wet deposition. In addition, contributions to Hg wet deposition from decreases in anthropogenic emissions in NYS and nation-wide were quantified from

  16. Environmental concentrations of metals in the catalan stretch of the ebro river, Spain: assessment of temporal trends.

    PubMed

    Vilavert, Lolita; Sisteré, Clara; Schuhmacher, Marta; Nadal, Martí; Domingo, José L

    2015-02-01

    The aim of this study was to investigate the environmental impact and the human health risks associated with exposure to a number of metals before and after initiating the decontamination process in Flix dam (Catalonia, Spain). The concentrations of As, Cd, Cr, Cu, Mn, Hg, Ni, and Pb were determined in samples of drinking water, river water, and soils collected in the Catalan stretch of the Ebro River, Spain. The results were compared with those of previous surveys performed in the same zones. Human exposure to metals, as well as the associated carcinogenic and non-carcinogenic risks, was also estimated. In river and drinking waters, most analyzed metals showed increases, being significant that of Cr. The movements of polluted sludge in Flix dam could be the reason for the Cr levels found in the current survey. However, Hg was not detected in both drinking and river waters. Important differences on Mn levels were found, being higher those in river water than in drinking water. In turn, although soil concentrations of all analyzed metals showed a decreasing temporal trend, the reductions were only significant for Ni. The hazard quotient (HQ) of all elements was below the unity, considered the safe threshold. For carcinogenic risks, all values were found to be lower than 10(-5), which has been defined as the maximum recommended excess of cancer risk according to the Spanish Legislation. The only exception was the As exposure through soil and drinking water, which slightly exceeded this threshold. The current results indicate the need to perform a continuous assessment of metal levels not only in river waters, but also in drinking water in order to assure the harmlessness of the decontamination process for the health of the population living downriver (Ebro) the Flix dam.

  17. Land use, organochlorine compound concentrations, and trends in benthic-invertebrate communities in selected stream basins in Chester County, Pennsylvania

    USGS Publications Warehouse

    Hardy, Mark A.; Wetzel, Kim L.; Moore, Craig R.

    1995-01-01

    Land use was analyzed for the drainage areas of 26 stream sites in Chester County, Pa., that cover a total area of 227 square miles or about 30 percent of the country. The most significant land-use changes during 1967-87 were decreased agricultural land use, increased residential land use, and increased commercial and industrial land use. Bulk samples of stream-bottom materials were collected at 42 sites in the study area from October 1985 through November 1987 and analyzed for content of organochlorine pesticides and polychlorinated biphenyls (PCB's). Organochlorine compounds and (or) PCB's were detected in streambed materials collected at 40 of the 42 sites sampled. The most enriched compounds (greater than 15 micrograms per kilogram) were PCB's, chlordane, and DDT plus its breakdown products. Data suggest that chlordane residues are closely associated with residential land use. PCB residues are closely associated with industrial and commercial land use. Cores of labeled sediments from the site of Icedale Lake, a drained reservoir on the West Branch Brandywine Creek, indicate that DDT was the first organochlorine pesticide to enter the Brandywine Creek; concentrations peaked in the late 1940's and early 1950's. As DDT influx subsequently decreased, influxes of chlordane and dieldrin increased and peaked in the mind-1960's, before the Chester County biological monitoring program. Influx of all pesticides appears to have decreased significantly since the 1960's. Contingency analyses showed that the relation between the Kendall slope estimator for trend and the increases in residential land use of 12 percent or greater were significant at the 95-percent confidence level. The contingency tables also showed that the relation between diversity indices of less than 2.25 and organochlorine-compound concentrations greater than 45 micrograms per kilogram was significant at the 95-percent confidence level.

  18. Study of temporal variation of radon concentrations in public drinking water supplies

    SciTech Connect

    York, E.L.

    1995-12-31

    The Environmental Protection Agency (EPA) has proposed a Maximum Contaminant Level (MCL) for radon-222 in public drinking water supplies of 300 pCi/L. Proposed monitoring requirements include collecting quarterly grab samples for the first year, then annual samples for the remainder of the compliance cycle provided first year quarterly samples average below the MCL. The focus of this research was to study the temporal variation of groundwater radon concentrations to investigate how reliably one can predict an annual average radon concentration based on the results of grab samples. Using a {open_quotes}slow-flow{close_quotes} collection method and liquid scintillation analysis, biweekly water samples were taken from ten public water supply wells in North Carolina (6 month - 11 month sampling periods). Based on study results, temporal variations exist in groundwater radon concentrations. Statistical analysis performed on the data indicates that grab samples taken from each of the ten wells during the study period would exhibit groundwater radon concentrations within 30% of their average radon concentration.

  19. Determination of radon concentration levels in well water in Konya, Turkey.

    PubMed

    Erdogan, M; Eren, N; Demirel, S; Zedef, V

    2013-10-01

    Radon ((222)Rn) measurements were undertaken in 16 samples of well water representing different depths and different types of aquifers found at the city centre of Konya, Central Turkey. The radon activity concentrations of the well water samples collected in the spring and summer seasons of 2012 were measured by using the radon gas analyser (AlphaGUARD PQ 2000PRO). The radon concentrations for spring and summer seasons are 2.29 ± 0.17 to 27.25 ± 1.07 and 1.44 ± 0.18 to 27.45 ± 1.25 Bq l(-1), respectively. The results at hand revealed that the radon concentration levels of the waters strictly depend on the seasons and are slightly variable with depth. Eleven of the 16 well water samples had radon concentration levels below the safe limit of 11.11 Bq l(-1) recommended by the United States Environmental Protection Agency. However, all measured radon concentration levels are well below the 100 Bq l(-1) safe limit declared by the World Health Organisation. The doses resulting from the consumption of these waters were calculated. The calculated minimum and maximum effective doses are 0.29 and 5.49 µSv a(-1), respectively. PMID:23595410

  20. Sources and preparation of data for assessing trends in concentrations of pesticides in streams of the United States, 1992-2006

    USGS Publications Warehouse

    Martin, Jeffrey D.

    2009-01-01

    This report provides a water-quality data set of 44 commonly used pesticides and 8 pesticide degradates suitable for a national assessment of trends in pesticide concentrations in streams of the United States. Water-quality samples collected from January 1992 through August 2006 at stream-water sites of the U.S. Geological Survey National Water-Quality Assessment Program and the National Stream Quality Accounting Network Program were compiled, reviewed, selected, and prepared for trend analysis as described in this report. Samples analyzed at the U.S. Geological Survey National Water Quality Laboratory by a gas chromatography/mass spectrometry analytical method were the most extensive in time and space and were selected for national trend analysis. The selection criteria described in the report produced a trend data set of 16,869 pesticide samples at 201 stream and river sites.

  1. Indoor and outdoor Radon concentration measurements in Sivas, Turkey, in comparison with geological setting.

    PubMed

    Mihci, Metin; Buyuksarac, Aydin; Aydemir, Attila; Celebi, Nilgun

    2010-11-01

    Indoor and soil gas Radon ((222)Rn) concentration measurements were accomplished in two stages in Sivas, a central eastern city in Turkey. In the first stage, CR-39 passive nuclear track detectors supplied by the Turkish Atomic Energy Authority (TAEA) were placed in the selected houses throughout Sivas centrum in two seasons; summer and winter. Before the setup of detectors, a detailed questionnaire form was distributed to the inhabitants of selected houses to investigate construction parameters and properties of the houses, and living conditions of inhabitants. Detectors were collected back two months later and analysed at TAEA laboratories to obtain indoor (222)Rn gas concentration values. In the second stage, soil gas (222)Rn measurements were performed using an alphameter near the selected houses for the indoor measurements. Although (222)Rn concentrations in Sivas were quite low in relation with the allowable limits, they are higher than the average of Turkey. Indoor and soil gas (222)Rn concentration distribution maps were prepared seperately and these maps were applied onto the surface geological map. In this way, both surveys were correlated with the each other and they were interpreted in comparison with the answers of questionnaire and the geological setting of the Sivas centrum and the vicinity.

  2. Characterizing long-term radon concentration changes in a geothermal area for correlation with volcanic earthquakes and reservoir temperatures: A case study from Mt. Aso, southwestern Japan

    NASA Astrophysics Data System (ADS)

    Koike, Katsuaki; Yoshinaga, Tohru; Asaue, Hisafumi

    2014-04-01

    The purpose of this study is to characterize in detail the temporal changes in Rn (radon-222) concentration in soil gases near fumaroles and clarify its correlation with volcanic earthquakes and temperatures in two geothermal reservoirs. Mt. Aso crater in southwest Japan, which has two reservoirs on its western side estimated by magnetotelluric survey to be at about 2 km in depth, was selected for this study. For the long-term survey, the α scintillation counter method was used weekly for 12.5 years at the three hot springs within a 2-km range. Rn concentrations were calculated using the CRAS method, a calculation method that considers radioactive equilibrium or nonequilibrium state of the soil gas. Rn concentrations generally showed similar fluctuation patterns among the sites. CRAS was used as a new indicator for evaluating the age of the soil gas. This age corresponds to the elapsed time determined from the generation of Rn based on the measurement of the numbers of atoms of Rn and its daughter 218Po at the start of measurement. In comparing the Rn data with the history of earthquakes in the Aso caldera, volcanic seismicity was identified as a major controlling factor in the sudden increase and decrease in Rn concentration as a function of age. For more precise detections of change, Rn concentrations were measured continuously at one site by pumping soil gas from a borehole and using an ionization chamber over 2.5 years. Five chemical components (He, H2, N2, CH4, and CO2) were then measured by gas chromatography at 1-week intervals. Because Rn concentrations are affected strongly by atmospheric temperatures, the residual components were obtained by subtracting the trend of the components from the original data. Chemical component data were used to estimate the temperature and pressure in the reservoir at the site; temperatures ranged from 229 to 280 °C, (average 265 °C, average pressure 80 MPa). Residual Rn concentrations showed a clear correlation with

  3. Recent trends in nutrient concentrations in Estonian rivers as a response to large-scale changes in land-use intensity and life-styles.

    PubMed

    Iital, Arvo; Pachel, Karin; Loigu, Enn; Pihlak, Margus; Leisk, Ulle

    2010-01-01

    The aim of the study was assessment of changes in nutrient concentrations in Estonian rivers as a response to improved wastewater treatment and substantial reductions in the use of fertilisers and number of livestock during the past 15-20 years. A Mann-Kendall test and flow adjusted technique to assess recent trends have been used. Statistical analysis covered time series of 53 sampling sites on 40 rivers and streams in different hydro-geographical regions and varying human pressures. The results indicate a statistically significant downward trend in nitrogen concentration in 18 sampling stations during the studied period; only very few showed an upward trend. These decreases in total nitrogen (TN) relate mainly to (i) substantial reductions in the use of fertilisers, (ii) decreased area of agricultural land, (iii) decreased point source load and (iv) increased self-purification capacity of soil-water systems. The concentration of phosphorus decreased only in 13 locations, despite of efforts to improve the efficiency of wastewater treatment. Moreover, in seven locations the concentration of phosphorus was increasing. This increase in total phosphorus (TP) probably relates to the low treatment efficiency of small wastewater treatment facilities as well as to the raised ground water table due to insufficient maintenance of drainage systems that favour transport of soil P to water bodies. Accordingly, the ratio of nitrogen and phosphorus had both decreasing and increasing trends.

  4. Application of a Weighted Regression Model for Reporting Nutrient and Sediment Concentrations, Fluxes, and Trends in Concentration and Flux for the Chesapeake Bay Nontidal Water-Quality Monitoring Network, Results Through Water Year 2012

    USGS Publications Warehouse

    Chanat, Jeffrey G.; Moyer, Douglas L.; Blomquist, Joel D.; Hyer, Kenneth E.; Langland, Michael J.

    2016-01-01

    Inconsistencies related to changing laboratory methods were also examined via two manipulative experiments. In the first experiment, increasing and decreasing “stair-step” patterns of changes in censoring level, overall representing a factor-of-five change in the laboratory reporting limit, were artificially imposed on a 27-year record with no censoring and a period-of-record concentration trend of –68.4 percent. Trends estimated on the basis of the manipulated records were broadly similar to the original trend (–63.6 percent for decreasing censoring levels and –70.3 percent for increasing censoring levels), lending a degree of confidence that the survival regression routines upon which WRTDS is based are generally robust to data censoring. The second experiment considered an abrupt disappearance of low-concentration observations of total phosphorus, associated with a laboratory method change and not reflected through censoring, near the middle of a 28-year record. By process of elimination, an upward shift in the estimated flow-normalize concentration trend line around the same time was identified as a likely artifact resulting from the laboratory method change, although a contemporaneous change in watershed processes cannot be ruled out. Decisions as to how to treat records with potential sampling protocol or laboratory methods-related artifacts should be made on a case-by-case basis, and trend results should be appropriately qualified.

  5. Application of a Weighted Regression Model for Reporting Nutrient and Sediment Concentrations, Fluxes, and Trends in Concentration and Flux for the Chesapeake Bay Nontidal Water-Quality Monitoring Network, Results Through Water Year 2012

    USGS Publications Warehouse

    Chanat, Jeffrey G.; Moyer, Douglas L.; Blomquist, Joel D.; Hyer, Kenneth E.; Langland, Michael J.

    2016-01-13

    Inconsistencies related to changing laboratory methods were also examined via two manipulative experiments. In the first experiment, increasing and decreasing “stair-step” patterns of changes in censoring level, overall representing a factor-of-five change in the laboratory reporting limit, were artificially imposed on a 27-year record with no censoring and a period-of-record concentration trend of –68.4 percent. Trends estimated on the basis of the manipulated records were broadly similar to the original trend (–63.6 percent for decreasing censoring levels and –70.3 percent for increasing censoring levels), lending a degree of confidence that the survival regression routines upon which WRTDS is based are generally robust to data censoring. The second experiment considered an abrupt disappearance of low-concentration observations of total phosphorus, associated with a laboratory method change and not reflected through censoring, near the middle of a 28-year record. By process of elimination, an upward shift in the estimated flow-normalize concentration trend line around the same time was identified as a likely artifact resulting from the laboratory method change, although a contemporaneous change in watershed processes cannot be ruled out. Decisions as to how to treat records with potential sampling protocol or laboratory methods-related artifacts should be made on a case-by-case basis, and trend results should be appropriately qualified.

  6. Concentrations of organic contaminants in mollusks and sediments at NOAA National Status and Trend sites in the coastal and estuarine United States.

    PubMed

    O'Connor, T P

    1991-01-01

    Mean concentrations of PAHs, PCBs, and DDT in mollusks and sediments at sites in the National Status and Trends Program (NST) are distributed in log-normal fashion. The dry weight-based chlorinated organic concentrations in mollusks generally exceed those in nearby sediments by an order of magnitude. PAHs are found at similar concentrations in sediments and mollusks. Highest concentrations of PCBs and DDT in mollusks are in the ranges of 1000 to 4000 ng/g (dry) and 400 to 1000 ng/g (dry), respectively. The highest PAH concentrations in sediments are in the 10,000 to 50,000 ng/g (dry) range. While higher concentrations of contaminants can be found by sampling localized hot spots, the NST data represent the distribution of concentrations over general areas of the coastal United States.

  7. Trends in Surface-Water Nitrate-N Concentrations and Loads from Predominantly-Forested Watersheds of the Chesapeake Bay Basin

    NASA Astrophysics Data System (ADS)

    Eshleman, K. N.

    2011-12-01

    Water quality monitoring data from streams and rivers provide the "gold standard" by which progress toward achieving real reductions in nutrient loadings to Chesapeake Bay must ultimately be assessed. The most recent trend results posted at the Chesapeake Bay Program (CBP) website reveal that a substantial percentage of tributaries are now showing long-term declines in flow-adjusted concentrations of nutrients and sediments: 22 sites showed statistically significant (p < 0.05) downward trends (1985-2010) in flow-adjusted concentrations, two sites showed upward trends, and eight sites showed no trend. Based on the data, the CBP has drawn the following conclusion: "At many monitored locations, long-term trends indicate that management actions, such as pollution controls for improved wastewater treatment plants and practices to reduce nutrients on farms and suburban lands, have reduced concentrations of nitrogen." But could this conclusion be pre-mature? I recently undertook a comparable analysis of long-term nitrate-N trends for a different group of watersheds (all located in the Chesapeake Bay watershed with long data records); this group includes nine watersheds that are predominantly (i.e., >75%) forested, plus five other Potomac River subwatersheds added for comparison. Based on comparable data and analytical methods to those used by CBP partners and USGS, 13 of the 14 sites-including both Potomac River stations (Chain Bridge at Washington DC and Hancock, Maryland)-showed statistically significant decreasing linear trends in annual flow-weighted nitrate-N concentration. Only one station-the heavily agricultural Upper Monocacy River-did not show a statistically significant (p < 0.05) trend. Five of the predominantly-forested watersheds also showed statistically significant decreasing trends in annual nitrate-N loads, and none of the stations showed a trend in annual runoff presumably due to high inter-annual hydroclimatological variability. While the largest

  8. Outdoor (222)Rn-concentrations in Germany - part 2 - former mining areas.

    PubMed

    Kümmel, M; Dushe, C; Müller, S; Gehrcke, K

    2014-06-01

    In the German Federal States of Saxony, Saxony-Anhalt and Thuringia, centuries of mining and milling activities resulted in numerous residues with increased levels of natural radioactivity such as waste rock dumps and tailings ponds. These may have altered potential radiation exposures of the population significantly. Especially waste rock dumps from old mining activities as well as 20th century uranium mining may, due to their radon ((222)Rn) exhalation capacity, lead to significant radiation exposures. They often lie close to or within residential areas. In order to study the impact on the natural radon level, the Federal Office for Radiation Protection (BfS) has run networks of radon measurement points in 16 former mining areas, together with 2 networks in regions not influenced by mining for comparison purposes. Representative overviews of the long-term outdoor radon concentrations could be established including estimates of regional background concentrations. Former mining and milling activities did not result in large-area impacts on the outdoor radon level. However, significantly increased radon concentrations were observed in close vicinity of shafts and large waste rock dumps. They are partly located in residential areas and need to be considered under radiation protection aspects. Examples are given that illustrate the consequences of the Wismut Ltd. Company's reclamation activities on the radon situation.

  9. Radon concentration in soil gas around local disjunctive tectonic zones in the Krakow area.

    PubMed

    Swakoń, J; Kozak, K; Paszkowski, M; Gradziński, R; Łoskiewicz, J; Mazur, J; Janik, M; Bogacz, J; Horwacik, T; Olko, P

    2005-01-01

    The purpose of this study was to investigate radon in the vicinity of geologic fault zones within the Krakow region of Poland, and to determine the influence of such formations on enhanced radon concentrations in soil. Radon ((222)Rn and (220)Rn) concentration measurements in soil gas (using ionization chamber AlphaGUARD PQ2000 PRO and diffusion chambers with CR-39 detectors), as well as radioactive natural isotopes of radium, thorium and potassium in soil samples (using gamma ray spectrometry with NaI(Tl) and HPGe detectors), were performed. Site selection was based on a geological map of Krakow. Geophysical methods (ground penetrating radar and shallow acoustic seismic) were applied to recognize the geological structure of the area and to locate the predicted courses of faults. Elevated levels of radon and thoron in soil gas were found in the study area when compared with those observed in an earlier survey covering Krakow agglomeration. For (222)Rn, the arithmetic mean of registered concentration values was 39 kBq/m(3) (median: 35.5 kBq/m(3)). For (220)Rn, the arithmetic mean was 10.8 kBq/m(3) and median 11.8 kBq/m(3).

  10. Outdoor (222)Rn-concentrations in Germany - part 2 - former mining areas.

    PubMed

    Kümmel, M; Dushe, C; Müller, S; Gehrcke, K

    2014-06-01

    In the German Federal States of Saxony, Saxony-Anhalt and Thuringia, centuries of mining and milling activities resulted in numerous residues with increased levels of natural radioactivity such as waste rock dumps and tailings ponds. These may have altered potential radiation exposures of the population significantly. Especially waste rock dumps from old mining activities as well as 20th century uranium mining may, due to their radon ((222)Rn) exhalation capacity, lead to significant radiation exposures. They often lie close to or within residential areas. In order to study the impact on the natural radon level, the Federal Office for Radiation Protection (BfS) has run networks of radon measurement points in 16 former mining areas, together with 2 networks in regions not influenced by mining for comparison purposes. Representative overviews of the long-term outdoor radon concentrations could be established including estimates of regional background concentrations. Former mining and milling activities did not result in large-area impacts on the outdoor radon level. However, significantly increased radon concentrations were observed in close vicinity of shafts and large waste rock dumps. They are partly located in residential areas and need to be considered under radiation protection aspects. Examples are given that illustrate the consequences of the Wismut Ltd. Company's reclamation activities on the radon situation. PMID:24508448

  11. Radon concentration in soil gas around local disjunctive tectonic zones in the Krakow area.

    PubMed

    Swakoń, J; Kozak, K; Paszkowski, M; Gradziński, R; Łoskiewicz, J; Mazur, J; Janik, M; Bogacz, J; Horwacik, T; Olko, P

    2005-01-01

    The purpose of this study was to investigate radon in the vicinity of geologic fault zones within the Krakow region of Poland, and to determine the influence of such formations on enhanced radon concentrations in soil. Radon ((222)Rn and (220)Rn) concentration measurements in soil gas (using ionization chamber AlphaGUARD PQ2000 PRO and diffusion chambers with CR-39 detectors), as well as radioactive natural isotopes of radium, thorium and potassium in soil samples (using gamma ray spectrometry with NaI(Tl) and HPGe detectors), were performed. Site selection was based on a geological map of Krakow. Geophysical methods (ground penetrating radar and shallow acoustic seismic) were applied to recognize the geological structure of the area and to locate the predicted courses of faults. Elevated levels of radon and thoron in soil gas were found in the study area when compared with those observed in an earlier survey covering Krakow agglomeration. For (222)Rn, the arithmetic mean of registered concentration values was 39 kBq/m(3) (median: 35.5 kBq/m(3)). For (220)Rn, the arithmetic mean was 10.8 kBq/m(3) and median 11.8 kBq/m(3). PMID:15511556

  12. Mercury concentrations in king penguin (Aptenodytes patagonicus) feathers at Crozet Islands (sub-Antarctic): temporal trend between 1966--1974 and 2000--2001.

    PubMed

    Scheifler, Renaud; Gauthier-Clerc, Michel; Le Bohec, Céline; Crini, Nadia; Coeurdassier, Michaël; Badot, Pierre-Marie; Giraudoux, Patrick; Le Maho, Yvon

    2005-01-01

    Remote sub-Antarctic islands and their wildlife may be contaminated by mercury via atmospheric and oceanic currents. Because of mercury's high toxicity and its capacity to be biomagnified in marine food chains, top predators like seabirds may be threatened by secondary poisoning. The present study provides data regarding mercury concentrations in breast feathers sampled in 2000 and 2001 on king penguins (Aptenodytes patagonicus) living at Crozet Islands. These contemporary concentrations were compared to those measured in feathers of king penguins sampled in the same colony between 1966 and 1974 and preserved in a museum (1970s sample). The average concentration of the contemporary sample is 1.98 microg g(-1) (dry mass) and is significantly different than the concentrations reported in some other penguin species. The concentration of the contemporary sample is significantly lower than the concentration of the 1970s sample (2.66 microg g(-1)). This suggests that mercury concentrations in southern hemisphere seabirds do not increase, which conflicts with the trends observed in the northern hemisphere. This difference in temporal trends between the northern and southern hemispheres usually is attributed mainly to a higher degree of pollutant emission in the northern hemisphere. Parameters that may explain the interspecies differences in mercury concentrations are discussed. These first results may constitute a basis for further ecotoxicological and/or biomonitoring studies of king penguins in these remote ecosystems. PMID:15683175

  13. An increase in the biogenic aerosol concentration as a contributing factor to the recent wetting trend in Tibetan Plateau

    PubMed Central

    Fang, Keyan; Makkonen, Risto; Guo, Zhengtang; Zhao, Yan; Seppä, Heikki

    2015-01-01

    A significant wetting trend since the early 1980s in Tibetan Plateau (TP) is most conspicuous in central and eastern Asia as shown in the instrumental data and the long-term moisture sensitive tree rings. We found that anomalies in the large-scale oceanic and atmospheric circulations do not play a significant role on the wetting trend in TP. Meanwhile, the weak correlation between local temperature and precipitation suggests that the temperature-induced enhancement of the local water cycle cannot fully explain the wetting trend either. This may indicate the presence of nonlinear processes between local temperature and precipitation. We hypothesize that the current warming may enhance the emissions of the biogenic volatile organic compounds (BVOC) that can increase the secondary organic aerosols (SOA), contributing to the precipitation increase. The wetting trend can increase the vegetation cover and cause a positive feedback on the BVOC emissions. Our simulations indicate a significant contribution of increased BVOC emissions to the regional organic aerosol mass and the simulated increase in BVOC emissions is significantly correlated with the wetting trend in TP. PMID:26411261

  14. An increase in the biogenic aerosol concentration as a contributing factor to the recent wetting trend in Tibetan Plateau.

    PubMed

    Fang, Keyan; Makkonen, Risto; Guo, Zhengtang; Zhao, Yan; Seppä, Heikki

    2015-01-01

    A significant wetting trend since the early 1980s in Tibetan Plateau (TP) is most conspicuous in central and eastern Asia as shown in the instrumental data and the long-term moisture sensitive tree rings. We found that anomalies in the large-scale oceanic and atmospheric circulations do not play a significant role on the wetting trend in TP. Meanwhile, the weak correlation between local temperature and precipitation suggests that the temperature-induced enhancement of the local water cycle cannot fully explain the wetting trend either. This may indicate the presence of nonlinear processes between local temperature and precipitation. We hypothesize that the current warming may enhance the emissions of the biogenic volatile organic compounds (BVOC) that can increase the secondary organic aerosols (SOA), contributing to the precipitation increase. The wetting trend can increase the vegetation cover and cause a positive feedback on the BVOC emissions. Our simulations indicate a significant contribution of increased BVOC emissions to the regional organic aerosol mass and the simulated increase in BVOC emissions is significantly correlated with the wetting trend in TP. PMID:26411261

  15. Measuring effective radium concentration with large numbers of samples. Part I--experimental method and uncertainties.

    PubMed

    Girault, Frédéric; Perrier, Frédéric

    2012-11-01

    Effective radium concentration EC(Ra), product of radium concentration and radon emanation, is the source term for radon release into the pore space of rocks and the environment. To measure EC(Ra), we have conducted, over a period of three years, more than 5500 radon-222 accumulation experiments in the laboratory with scintillation flasks, and about 700 with integrating solid state nuclear track detectors, leading to experimental values of EC(Ra) for more than 1570 rock and soil samples. Through detailed systematic checks and intercomparison between various repeated experiments, the experimental uncertainty has been assessed, and ranges from 30% (1 σ) for EC(Ra) values smaller than 0.2 Bq kg(-1) to about 8-10% for EC(Ra) values larger than 50 Bq kg(-1). The detection limit, defined as the 90% probability for obtaining a non-zero experimental EC(Ra) value at 68% confidence level, depends on the mass of the sample with respect to the volume of the accumulation volume, and typically varies between 0.04 and 0.09 Bq kg(-1). To measure EC(Ra) from large numbers of samples with sufficient accuracy and uncertainty for our purpose, i.e. for the most natural objects encountered in the environment, the accumulation method with scintillation flask emerged as particularly useful and robust. Properties of EC(Ra) and interpretations inferred from this large data set are presented in the companion paper.

  16. Measuring effective radium concentration with large numbers of samples. Part II--general properties and representativity.

    PubMed

    Girault, Frédéric; Perrier, Frédéric

    2012-11-01

    Effective radium concentration EC(Ra), product of radium concentration and radon emanation, is the source term for radon release into the pore space of rocks and the environment. Over a period of three years, we performed more than 6000 radon-222 accumulation experiments in the laboratory with scintillation flasks and SSNTDs and we obtained experimental EC(Ra) values from more than 1570 rock and soil samples. With this method, which allowed the measurement of EC(Ra) from large numbers of samples with sufficient accuracy and uncertainty, as detailed in the companion paper, the dependence of the emanation factor on temperature and moisture content is revisited. In addition, with such a large EC(Ra) dataset, dispersion of EC(Ra) can be studied at sample-scale (cm to dm) and at scarp-scale (m to tens of m). Furthermore, we are able to discuss the representativity of obtained EC(Ra) values at field-scale, and to investigate the spatial variations of EC(Ra) over kilometric scales, within geological formations and across formations and faults. This experimental study opens new perspectives in the understanding of radium geochemistry and illustrates the importance of studying the radon source term with large numbers of samples for the modelling of geological and environmental processes, and also for the assessment of the radon health hazard.

  17. A study of atmospheric radon gas concentrations in water extraction wells of Hamadan, western Iran.

    NASA Astrophysics Data System (ADS)

    Gillmore, Gavin; Jabari Vasal, Naghi

    2010-05-01

    It is well known that half of the radiation received by humans is due to the presence of radon (222Rn) in the built environment. As part of a project measuring indoor radon in Hamadan, western Iran, a survey was undertaken of atmospheric radon in 28 wells in the region using a Sarad Doseman. Specific geological features of this settlement include highly permeable alluvial fan deposits which result in radon being released to the atmosphere. The observed radon concentrations in well shafts(between 1,000 Bq m3 and 36,600 Bq m3) show considerable variability both in space and time. One aspect of this study was to also assess whether there was a relationship between the depth of a well and the measured atmospheric radon concentration. The importance of such measurements in this region is highlighted by the fact that radon levels in homes in Hamadan are probably greatly influenced by the porous nature of this underlying geology and its use as a water reservoir / conduit through the application of qanat technology.

  18. The Relative Effects of Hydrology, Ecology, and Climate on Temporal Trends and Spatial Patterns of Stream Nitrate Concentrations in the Catskill Mountains, New York, USA

    NASA Astrophysics Data System (ADS)

    Burns, D. A.; Lovett, G. M.; Murdoch, P. S.

    2004-12-01

    The Catskill Mountains of New York receive 10 to 15 kg ha-1 yr-1 of nitrogen (N) in atmospheric deposition, among the highest rates in eastern North America. Consequently, streams in the Catskills have relatively high nitrate (NO3-) concentrations (mean of stream surveys = 20 to 30 μ mol L-1 at baseflow), which contribute to chronic and episodic stream acidification. Stream chemistry monitoring in the 1980s showed an increasing trend in NO3- concentrations that was attributed to N saturation, a condition whereby continued high rates of atmospheric N deposition in combination with a maturing forest result in gradually decreasing ecosystem N retention. This increasing trend reversed itself during the early 1990s, a pattern that was partially attributed to an intense region-wide soil freezing event in December 1989. Stream NO3- concentrations remained relatively low at long-term monitoring sites from 1992-03 despite relatively constant atmospheric N deposition rates from the 1980s through 2003, suggesting that a simple interpretation of the N saturation model is not valid on decadal time scales. The discovery of groundwater seeps with relatively high NO3- concentrations in the 1990s led to a hypothesis that the presence of seeps in the Catskills may be controlling spatial variability in stream NO3- concentrations, which range from near 0 to about 50 μ mol L-1 at baseflow. Subsequent research indicated these variations in stream NO3- concentrations are likely controlled by variations in tree species dominance. Nitrate concentrations in drainage waters are highest in stands of sugar maple and yellow birch and lowest in red oak and hemlock stands. One study, however, showed that NO3- concentrations in shallow groundwater were correlated with a topographic index that is a surrogate for soil moisture suggesting that covariance of tree species and soil moisture may amplify the apparent differences in NO3- concentrations previously attributed solely to differences in tree

  19. Comparison of Ambient Radon Concentrations in Air in the Northern Mojave Desert from Continuous and Integrating Instruments

    SciTech Connect

    David S. Shafer; David McGraw; Lynn H. Karr; Greg McCurdy; Tammy L. Kluesner; Karen J. Gray; Jeffrey Tappen

    2010-05-18

    As part of a program to characterize and baseline environmental parameters, ambient radon-222 (Rn) monitoring was conducted in the rural community of Amargosa Valley, NV, the closest community to Yucca Mountain. Passive integrating and continuous Rn monitoring instruments were deployed adjacent to the Community Environmental Monitoring Program (CEMP) station in Amargosa Valley. The CEMP station provided real-time ambient gamma exposure and meteorological data used to correct the integrated Rn measurements, verified the meteorological data collected by the continuous Rn monitoring instrument, and for provided instrumentation for evaluating the relationships between meteorological conditions and Rn concentrations. Hourly Rn concentrations in air measured by the continuous Rn monitoring instrument (AlphaGUARD®) were compared to the average hourly values for the integrating Rn measurements (E-PERM®) by dividing the total Rn measurements by the number of hours the instruments were deployed. The results of the comparison indicated that average hourly ambient Rn concentrations as measured by both methods ranged from 0.2 to 0.4 pico-curies per liter of air. Ambient Rn values for the AlphaGUARD exhibited diurnal variations. When Rn concentrations were compared with measurements of temperature (T), barometric pressure, and relative humidity, the correlation (inversely) was highest with T, albeit weakly.

  20. Global average concentration and trend for hydroxyl radicals deduced from ALE/GAGE trichloroethane (methyl chloroform) data for 1978-1990

    NASA Technical Reports Server (NTRS)

    Prinn, R.; Cunnold, D.; Simmonds, P.; Alyea, F.; Boldi, R.; Crawford, A.; Fraser, P.; Gutzler, D.; Hartley, D.; Rosen, R.

    1992-01-01

    An optimal estimation inversion scheme is utilized with atmospheric data and emission estimates to determined the globally averaged CH3CCl3 tropospheric lifetime and OH concentration. The data are taken from atmospheric measurements from surface stations of 1,1,1-trichloroethane and show an annual increase of 4.4 +/- 0.2 percent. Industrial emission estimates and a small oceanic loss rate are included, and the OH concentration for the same period (1978-1990) are incorporated at 1.0 +/- 0.8 percent/yr. The positive OH trend is consistent with theories regarding OH and ozone trends with respect to land use and global warming. Attention is given to the effects of the ENSO on the CH3CCl3 data and the assumption of continuing current industrial anthropogenic emissions. A novel tropical atmospheric tracer-transport mechanism is noted with respect to the CH3CCl3 data.

  1. Historical trends (1998-2012) of nickel (Ni), copper (Cu) and chromium (Cr) concentrations in marine sediments at four locations in the Northern Adriatic Sea.

    PubMed

    Traven, Luka; Furlan, Nikolina; Cenov, Arijana

    2015-09-15

    Historical trends (1998-2012) nickel (Ni), copper (Cu) and chromium (Cr) concentrations in marine sediments were assessed at four locations in the Northern Adriatic Sea (Croatia) in the proximity of an oil refinery. Ecological risks were characterized by benchmarking the dataset against Sediment Quality Guidelines (SQG). A significant number of samples had Ni values above ERL with no exceedance of the ERL values for Cu and Cr. Weak positive historical trends were found for only for Cu. At all sites there were statistically significant correlations between Ni and Cr indicating a common origin of these heavy metals in the investigated marine sediments. There were statistically significant differences between the sites under the direct influence of the oil refinery compared to the control site indicating the possibility that the oil refinery is contributing to the concentration of these heavy metals in the marine sediments.

  2. Historical trends (1998-2012) of nickel (Ni), copper (Cu) and chromium (Cr) concentrations in marine sediments at four locations in the Northern Adriatic Sea.

    PubMed

    Traven, Luka; Furlan, Nikolina; Cenov, Arijana

    2015-09-15

    Historical trends (1998-2012) nickel (Ni), copper (Cu) and chromium (Cr) concentrations in marine sediments were assessed at four locations in the Northern Adriatic Sea (Croatia) in the proximity of an oil refinery. Ecological risks were characterized by benchmarking the dataset against Sediment Quality Guidelines (SQG). A significant number of samples had Ni values above ERL with no exceedance of the ERL values for Cu and Cr. Weak positive historical trends were found for only for Cu. At all sites there were statistically significant correlations between Ni and Cr indicating a common origin of these heavy metals in the investigated marine sediments. There were statistically significant differences between the sites under the direct influence of the oil refinery compared to the control site indicating the possibility that the oil refinery is contributing to the concentration of these heavy metals in the marine sediments. PMID:26146134

  3. Spatial and temporal trends in contaminant concentrations in Hexagenia nymphs following a coal ash spill at the Tennessee Valley Authority's Kingston Fossil Plant

    DOE PAGES

    Baker, Tyler F; Jett, Robert Trent; Smith, John G.; Murphy, Cheryl A.

    2016-02-25

    A dike failure at the Tennessee Valley Authority Kingston Fossil Plant in East Tennessee, United States, in December 2008, released approximately 4.1 million m3 of coal ash into the Emory River. From 2009 through 2012, samples of mayfly nymphs (Hexagenia bilineata) were collected each spring from sites in the Emory, Clinch, and Tennessee Rivers upstream and downstream of the spill. Samples were analyzed for 17 metals. Concentrations of metals were generally highest the first 2 miles downstream of the spill, and then decreased with increasing distance from the spill. Arsenic, B, Ba, Be, Mo, Sb, Se, Sr, and V appearedmore » to have strong ash signatures, whereas Co, Cr, Cu, Ni, and Pb appeared to be associated with ash and other sources. Furthermore, the concentrations for most of these contaminants were modest and are unlikely to cause widespread negative ecological effects. Trends in Hg, Cd, and Zn suggested little (Hg) or no (Cd, Zn) association with ash. Temporal trends suggested that concentrations of ash-related contaminants began to subside after 2010, but because of the limited time period of that analysis (4 yr), further monitoring is needed to verify this trend. The present study provides important information on the magnitude of contaminant exposure to aquatic receptors from a major coal ash spill, as well as spatial and temporal trends for transport of the associated contaminants in a large open watershed. Environ Toxicol Chem 2016;35:1159 1171. Published 2015 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.« less

  4. Application Study of Comprehensive Forecasting Model Based on Entropy Weighting Method on Trend of PM2.5 Concentration in Guangzhou, China.

    PubMed

    Liu, Dong-jun; Li, Li

    2015-06-23

    For the issue of haze-fog, PM2.5 is the main influence factor of haze-fog pollution in China. The trend of PM2.5 concentration was analyzed from a qualitative point of view based on mathematical models and simulation in this study. The comprehensive forecasting model (CFM) was developed based on the combination forecasting ideas. Autoregressive Integrated Moving Average Model (ARIMA), Artificial Neural Networks (ANNs) model and Exponential Smoothing Method (ESM) were used to predict the time series data of PM2.5 concentration. The results of the comprehensive forecasting model were obtained by combining the results of three methods based on the weights from the Entropy Weighting Method. The trend of PM2.5 concentration in Guangzhou China was quantitatively forecasted based on the comprehensive forecasting model. The results were compared with those of three single models, and PM2.5 concentration values in the next ten days were predicted. The comprehensive forecasting model balanced the deviation of each single prediction method, and had better applicability. It broadens a new prediction method for the air quality forecasting field.

  5. Application Study of Comprehensive Forecasting Model Based on Entropy Weighting Method on Trend of PM2.5 Concentration in Guangzhou, China

    PubMed Central

    Liu, Dong-jun; Li, Li

    2015-01-01

    For the issue of haze-fog, PM2.5 is the main influence factor of haze-fog pollution in China. The trend of PM2.5 concentration was analyzed from a qualitative point of view based on mathematical models and simulation in this study. The comprehensive forecasting model (CFM) was developed based on the combination forecasting ideas. Autoregressive Integrated Moving Average Model (ARIMA), Artificial Neural Networks (ANNs) model and Exponential Smoothing Method (ESM) were used to predict the time series data of PM2.5 concentration. The results of the comprehensive forecasting model were obtained by combining the results of three methods based on the weights from the Entropy Weighting Method. The trend of PM2.5 concentration in Guangzhou China was quantitatively forecasted based on the comprehensive forecasting model. The results were compared with those of three single models, and PM2.5 concentration values in the next ten days were predicted. The comprehensive forecasting model balanced the deviation of each single prediction method, and had better applicability. It broadens a new prediction method for the air quality forecasting field. PMID:26110332

  6. Application Study of Comprehensive Forecasting Model Based on Entropy Weighting Method on Trend of PM2.5 Concentration in Guangzhou, China.

    PubMed

    Liu, Dong-jun; Li, Li

    2015-06-01

    For the issue of haze-fog, PM2.5 is the main influence factor of haze-fog pollution in China. The trend of PM2.5 concentration was analyzed from a qualitative point of view based on mathematical models and simulation in this study. The comprehensive forecasting model (CFM) was developed based on the combination forecasting ideas. Autoregressive Integrated Moving Average Model (ARIMA), Artificial Neural Networks (ANNs) model and Exponential Smoothing Method (ESM) were used to predict the time series data of PM2.5 concentration. The results of the comprehensive forecasting model were obtained by combining the results of three methods based on the weights from the Entropy Weighting Method. The trend of PM2.5 concentration in Guangzhou China was quantitatively forecasted based on the comprehensive forecasting model. The results were compared with those of three single models, and PM2.5 concentration values in the next ten days were predicted. The comprehensive forecasting model balanced the deviation of each single prediction method, and had better applicability. It broadens a new prediction method for the air quality forecasting field. PMID:26110332

  7. Variations and trends in PM2.5 mass, sulfate, and carbon concentrations at a rural and an urban site in New York State

    NASA Astrophysics Data System (ADS)

    Schwab, J. J.; Demerjian, K. L.; Rattigan, O. V.; Felton, H. D.

    2011-12-01

    PM2.5 mass and species concentrations using low volume samplers have been measured routinely at sites in New York State for more than a decade. We are analyzing this data for several sites to investigate both the overall trend in concentration and composition, and the year-to-year and season-to-season variations in these parameters. The sites chosen for this work are the rural station at Pinnacle State Park in Addison, NY; and the Queens College station in New York City. These two sites have an extensive array of continuous gas and aerosol phase pollutant measurements in addition to the filter samples used as the basis for this study. Over the past ten years the annual average PM2.5 mass concentrations have dropped about 3 μg m-3 at each of the two sites. However, there are indications that much of this decrease has occurred in the sulfate and inorganic components as a result of a variety of SOx and NOx emission controls implemented under the 1990 Clean Air Act Amendments. Specifically, the decreases in PM2.5 mass are mainly attributed to a decrease in particle sulfate (predominantly in summer) with a more modest decrease in particle nitrate in recent years. The carbonaceous component of the PM2.5 has not decreased proportionally, and in some cases has increased. This raises many interesting questions about the future trends and toxicity of PM2.5. Year-to-year and seasonal variations in the PM2.5 mass and composition, while limiting our ability to determine precise trends, also can give insight into the origin of the PM and, in some cases, the overall chemical and dynamical processes controlling ground level concentrations.

  8. Temporal trends in concentrations of DBCP and nitrate in groundwater in the eastern San Joaquin Valley, California, USA

    USGS Publications Warehouse

    Burow, K.R.; Dubrovsky, N.M.; Shelton, James L.

    2007-01-01

    Temporal monitoring of the pesticide 1,2-dibromo-3-chloropropane (DBCP) and nitrate and indicators of mean groundwater age were used to evaluate the transport and fate of agricultural chemicals in groundwater and to predict the long-term effects in the regional aquifer system in the eastern San Joaquin Valley, California. Twenty monitoring wells were installed on a transect along an approximate groundwater flow path. Concentrations of DBCP and nitrate in the wells were compared to concentrations in regional areal monitoring networks. DBCP persists at concentrations above the US Environmental Protection Agency's maximum contaminant level (MCL) at depths of nearly 40 m below the water table, more than 25 years after it was banned. Nitrate concentrations above the MCL reached depths of more than 20 m below the water table. Because of the intensive pumping and irrigation recharge, vertical flow paths are dominant. High concentrations (above MCLs) in the shallow part of the regional aquifer system will likely move deeper in the system, affecting both domestic and public-supply wells. The large fraction of old water (unaffected by agricultural chemicals) in deep monitoring wells suggests that it could take decades for concentrations to reach MCLs in deep, long-screened public-supply wells, however. ?? Springer-Verlag 2007.

  9. Temporal trends in concentrations of DBCP and nitrate in groundwater in the eastern San Joaquin Valley, California, USA

    NASA Astrophysics Data System (ADS)

    Burow, K. R.; Dubrovsky, N. M.; Shelton, J. L.

    2007-08-01

    Temporal monitoring of the pesticide 1,2-dibromo-3-chloropropane (DBCP) and nitrate and indicators of mean groundwater age were used to evaluate the transport and fate of agricultural chemicals in groundwater and to predict the long-term effects in the regional aquifer system in the eastern San Joaquin Valley, California. Twenty monitoring wells were installed on a transect along an approximate groundwater flow path. Concentrations of DBCP and nitrate in the wells were compared to concentrations in regional areal monitoring networks. DBCP persists at concentrations above the US Environmental Protection Agency’s maximum contaminant level (MCL) at depths of nearly 40 m below the water table, more than 25 years after it was banned. Nitrate concentrations above the MCL reached depths of more than 20 m below the water table. Because of the intensive pumping and irrigation recharge, vertical flow paths are dominant. High concentrations (above MCLs) in the shallow part of the regional aquifer system will likely move deeper in the system, affecting both domestic and public-supply wells. The large fraction of old water (unaffected by agricultural chemicals) in deep monitoring wells suggests that it could take decades for concentrations to reach MCLs in deep, long-screened public-supply wells, however.

  10. The role of diet on long-term concentration and pattern trends of brominated and chlorinated contaminants in western Hudson Bay polar bears, 1991-2007.

    PubMed

    McKinney, Melissa A; Stirling, Ian; Lunn, Nick J; Peacock, Elizabeth; Letcher, Robert J

    2010-11-15

    Adipose tissue was sampled from the western Hudson Bay (WHB) subpopulation of polar bears at intervals from 1991 to 2007 to examine temporal trends of PCB and OCP levels both on an individual and sum-(∑-)contaminant basis. We also determined levels and temporal trends of emerging polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCD), polybrominated biphenyls (PBBs) and other current-use brominated flame retardants. Over the 17-year period, ∑DDT (and p,p'-DDE, p,p'-DDD, p,p'-DDT) decreased (-8.4%/year); α-hexachlorocyclohexane (α-HCH) decreased (-11%/year); β-HCH increased (+8.3%/year); and ∑PCB and ∑chlordane (CHL), both contaminants at highest concentrations in all years (>1ppm), showed no distinct trends even when compared to previous data for this subpopulation dating back to 1968. Some of the less persistent PCB congeners decreased significantly (-1.6%/year to -6.3%/year), whereas CB153 levels tended to increase (+3.3%/year). Parent CHLs (c-nonachlor, t-nonachlor) declined, whereas non-monotonic trends were detected for metabolites (heptachlor epoxide, oxychlordane). ∑chlorobenzene, octachlorostyrene, ∑mirex, ∑MeSO(2)-PCB and dieldrin did not significantly change. Increasing ∑PBDE levels (+13%/year) matched increases in the four consistently detected congeners, BDE47, BDE99, BDE100 and BDE153. Although no trend was observed, total-(α)-HBCD was only detected post-2000. Levels of the highest concentration brominated contaminant, BB153, showed no temporal change. As long-term ecosystem changes affecting contaminant levels may also affect contaminant patterns, we examined the influence of year (i.e., aging or "weathering" of the contaminant pattern), dietary tracers (carbon stable isotope ratios, fatty acid patterns) and biological (age/sex) group on congener/metabolite profiles. Patterns of PCBs, CHLs and PBDEs were correlated with dietary tracers and biological group, but only PCB and CHL patterns were correlated with year. DDT

  11. The role of diet on long-term concentration and pattern trends of brominated and chlorinated contaminants in western Hudson Bay polar bears, 1991-2007.

    PubMed

    McKinney, Melissa A; Stirling, Ian; Lunn, Nick J; Peacock, Elizabeth; Letcher, Robert J

    2010-11-15

    Adipose tissue was sampled from the western Hudson Bay (WHB) subpopulation of polar bears at intervals from 1991 to 2007 to examine temporal trends of PCB and OCP levels both on an individual and sum-(∑-)contaminant basis. We also determined levels and temporal trends of emerging polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCD), polybrominated biphenyls (PBBs) and other current-use brominated flame retardants. Over the 17-year period, ∑DDT (and p,p'-DDE, p,p'-DDD, p,p'-DDT) decreased (-8.4%/year); α-hexachlorocyclohexane (α-HCH) decreased (-11%/year); β-HCH increased (+8.3%/year); and ∑PCB and ∑chlordane (CHL), both contaminants at highest concentrations in all years (>1ppm), showed no distinct trends even when compared to previous data for this subpopulation dating back to 1968. Some of the less persistent PCB congeners decreased significantly (-1.6%/year to -6.3%/year), whereas CB153 levels tended to increase (+3.3%/year). Parent CHLs (c-nonachlor, t-nonachlor) declined, whereas non-monotonic trends were detected for metabolites (heptachlor epoxide, oxychlordane). ∑chlorobenzene, octachlorostyrene, ∑mirex, ∑MeSO(2)-PCB and dieldrin did not significantly change. Increasing ∑PBDE levels (+13%/year) matched increases in the four consistently detected congeners, BDE47, BDE99, BDE100 and BDE153. Although no trend was observed, total-(α)-HBCD was only detected post-2000. Levels of the highest concentration brominated contaminant, BB153, showed no temporal change. As long-term ecosystem changes affecting contaminant levels may also affect contaminant patterns, we examined the influence of year (i.e., aging or "weathering" of the contaminant pattern), dietary tracers (carbon stable isotope ratios, fatty acid patterns) and biological (age/sex) group on congener/metabolite profiles. Patterns of PCBs, CHLs and PBDEs were correlated with dietary tracers and biological group, but only PCB and CHL patterns were correlated with year. DDT

  12. Trends in concentrations of atmospheric gaseous and particulate species in rural eastern Tennessee as related to primary emission reductions

    NASA Astrophysics Data System (ADS)

    Tanner, R. L.; Bairai, S. T.; Mueller, S. F.

    2015-09-01

    Air quality measurements at Look Rock, Tennessee - on the western edge of the Great Smoky Mountains National Park - were begun in 1980 and expanded during the 1980s to a National Park Service (NPS) IMPROVE network station. Measurements were expanded again by the Tennessee Valley Authority (TVA, 1999-2007) to examine the effects of electric generating unit (EGU) emission reductions of SO2 and NOx on air quality at the station. Analysis of temporal trends (1999-2013) has been conducted at the site in collaboration with activities related to the 2013 Southeast Atmosphere Study (SAS) at Look Rock and other southeastern US locations. Key findings from these trend studies include the observation that primary pollutant levels have consistently tracked emission reductions from EGUs and other primary sources in the region, but reductions in secondary pollutants such as particulate sulfate and, specifically, ozone have been smaller compared to reductions in primary emissions. Organic carbonaceous material (OM) remains a major contributor (30-40 % in the period 2009-2013) to fine particulate mass at the site, as confirmed by ACSM measurements at the site in 2013. A large portion (65-85 %) of carbon in OM derives from modern carbon sources based on 14C measurements. Important parameters affecting ozone levels, fine mass, and visibility also include the specific diurnal meteorology at this ridge-top site, its location in a predominantly mixed-deciduous forest, and the presence of primary sources of precursors at distances of 50-500 km from the site in all directions.

  13. Trends in concentrations of atmospheric gaseous and particulate species in rural eastern Tennessee as related to primary emissions reductions

    NASA Astrophysics Data System (ADS)

    Tanner, R. L.; Bairai, S. T.; Mueller, S. F.

    2015-05-01

    Air quality measurements at Look Rock, Tennessee - on the western edge of the Great Smoky Mountains National Park - were begun in 1980 and expanded during the 1980s to a National Park Service (NPS) IMPROVE network station. Measurements were expanded again by the Tennessee Valley Authority (TVA, 1999-2007) to examine the effects of electric generating unit (EGU) emission reductions of SO2 and NOx on air quality at the station. Analysis of temporal trends (1999-2013) has been conducted at the site in collaboration with activities related to the 2013 Southeast Atmosphere Study (SAS) at Look Rock and other southeastern US locations. Key findings from these trend studies include the observation that primary pollutant levels have consistently tracked emissions reductions from EGUs and other primary sources in the region but reductions in secondary pollutants such as particulate sulfate and, specifically, ozone have been smaller compared to reductions in primary emissions. Organic carbonaceous material (OM) remains a major contributor (30-40% in the period 2009-2013) to fine particulate mass at the site, as confirmed by ACSM measurements at the site in 2013. A large portion (65-85%) of carbon in OM derives from modern carbon sources based on 14C measurements. Important parameters affecting ozone levels, fine mass and visibility also include the specific diurnal meteorology at this ridge-top site, its location in a predominantly mixed-deciduous forest, and the presence of primary sources of precursors at distances of 50-500 km from the site in all directions.

  14. Trends in atmospheric concentrations of weed pollen in the context of recent climate warming in Poznań (Western Poland)

    NASA Astrophysics Data System (ADS)

    Bogawski, Paweł; Grewling, Łukasz; Nowak, Małgorzata; Smith, Matt; Jackowiak, Bogdan

    2014-10-01

    A significant increase in summer temperatures has been observed for the period 1996-2011 in Poznań, Poland. The phenological response of four weed taxa, widely represented by anemophilous species ( Artemisia spp., Rumex spp. and Poaceae and Urticaceae species) to this recent climate warming has been analysed in Poznań by examining the variations in the course of airborne pollen seasons. Pollen data were collected by 7-day Hirst-type volumetric trap. Trends in pollen seasons were determined using Mann-Kendall test and Sen's slope estimator, whereas the relationships between meteorological and aerobiological data were established by Spearman's rank correlation coefficient. Significant trends in pollen data were detected. The duration of pollen seasons of all analysed taxa increased (from +2.0 days/year for Urticaceae to +3.8 days/year for Rumex), which can be attributed to a delay in pollen season end dates rather than earlier start dates. In addition, the intensity of Artemisia pollen seasons significantly decreased and correlates with mean July-September daily minimum temperatures ( r = -0.644, p < 0.01). In contrast, no significant correlations were found between temperature and characteristics of Rumex pollen seasons. The results of this study show that observed shifts in weed pollen seasons in Poznań, i.e. longer duration and later end dates, might be caused by the recorded increase in summer temperature. This influence was the strongest in relation to Artemisia, which is the taxon that flowers latest in the year. The general lack of significant correlations between Rumex and Urticaceae pollen seasons and spring and/or summer temperature suggests that other factors, e.g. land use practices, could also be partially responsible for the observed shifts in pollen seasons.

  15. Trends in atmospheric concentrations of weed pollen in the context of recent climate warming in Poznań (Western Poland).

    PubMed

    Bogawski, Paweł; Grewling, Lukasz; Nowak, Małgorzata; Smith, Matt; Jackowiak, Bogdan

    2014-10-01

    A significant increase in summer temperatures has been observed for the period 1996-2011 in Poznań, Poland. The phenological response of four weed taxa, widely represented by anemophilous species (Artemisia spp., Rumex spp. and Poaceae and Urticaceae species) to this recent climate warming has been analysed in Poznań by examining the variations in the course of airborne pollen seasons. Pollen data were collected by 7-day Hirst-type volumetric trap. Trends in pollen seasons were determined using Mann-Kendall test and Sen's slope estimator, whereas the relationships between meteorological and aerobiological data were established by Spearman's rank correlation coefficient. Significant trends in pollen data were detected. The duration of pollen seasons of all analysed taxa increased (from +2.0 days/year for Urticaceae to +3.8 days/year for Rumex), which can be attributed to a delay in pollen season end dates rather than earlier start dates. In addition, the intensity of Artemisia pollen seasons significantly decreased and correlates with mean July-September daily minimum temperatures (r = -0.644, p < 0.01). In contrast, no significant correlations were found between temperature and characteristics of Rumex pollen seasons. The results of this study show that observed shifts in weed pollen seasons in Poznań, i.e. longer duration and later end dates, might be caused by the recorded increase in summer temperature. This influence was the strongest in relation to Artemisia, which is the taxon that flowers latest in the year. The general lack of significant correlations between Rumex and Urticaceae pollen seasons and spring and/or summer temperature suggests that other factors, e.g. land use practices, could also be partially responsible for the observed shifts in pollen seasons.

  16. Trends in nitrate concentrations and determination of its origin using stable isotopes (18O and 15N) in groundwater of the Western Central Valley, Costa Rica.

    PubMed

    Reynolds-Vargas, Jenny; Fraile-Merino, Julio; Hirata, Ricardo

    2006-08-01

    A study was conducted to evaluate long-term trends in nitrate concentrations and to try to identify the origin of nitrate using stable isotopes (15N(NO3-) and 18O(NO3-)) in the aquifers of the western Central Valley, Costa Rica, where more than 1 million people depend on groundwater to satisfy their daily needs. Data from 20 sites periodically sampled for 4 to 17 years indicate an increasing trend in nitrate concentrations at five sites, which in a period ranging from 10 to 40 years, will exceed recommended maximum concentrations. Results of isotopic analysis indicate a correspondence between land use patterns and the isotopic signature of nitrate in groundwater and suggest that urbanization processes without adequate waste disposal systems, followed by coffee fertilization practices, are threatening water quality in the region. We conclude that groundwater management in this area is not sustainable, and that land use substitution processes from agricultural activity to residential occupation that do not have proper sewage disposal systems may cause a significant increment in the nitrate contaminant load. PMID:16989507

  17. Radionuclides, inorganic constituents, organic compounds, and bacteria in water from selected wells and springs from the southern boundary of the Idaho National Engineering Laboratory to the Hagerman area, Idaho, 1992

    USGS Publications Warehouse

    Bartholomay, R.C.; Edwards, D.D.; Campbell, L.J.

    1994-01-01

    Dissolved concentrations of radon-222, a naturally occurring radioactive gas, are found in water in Idaho. The U.S. Geological Survey collected water samples for radon-222 analyses from 339 Idaho wells and springs during 1989-91. These water samples were collected as part of ongoing monitoring programs with the Idaho Department of Water Resources and the U.S. Department of Energy. Concentrations of dissolved radon-222 ranged from -58+30 to 5,715+66 picocuries per liter; the mean and median concentrations were 446+35 and 242+25 picocuries per liter, respectively.

  18. TEMPORAL TRENDS OF BLACK CARBON CONCENTRATIONS AND REGIONAL CLIMATE FORCING IN THE SOUTHEASTERN UNITED STATES. (R825248)

    EPA Science Inventory

    The effect of black carbon (BC) on climate forcing is potentially important, but its estimates have large uncertainties due to a lack of sufficient observational data. The BC mass concentration in the southeastern US was measured at a regionally representative site, Mount Gibb...

  19. Spatial and temporal trends in nitrate concentrations in the River Derwent, North Yorkshire, and its need for NVZ status.

    PubMed

    Mian, Ishaq A; Begum, Shaheen; Riaz, Muhammad; Ridealgh, Mike; McClean, Colin J; Cresser, Malcolm S

    2010-01-15

    Long-term spatial and temporal variations in nitrate-N concentrations along the River Derwent have been examined using Environment Agency data to investigate the relative importance of impacts of atmospheric N deposition, land use, and changes in management. Where moorland and rough grazing dominate upstream of Forge Valley and Malton, over the 20 years since 1988 mean nitrate-N concentrations were initially increasing significantly, but are now levelling off, with peaks at ca. 4.5 mg Nl(-1). As expected in a catchment in a nitrate vulnerable zone (NVZ), more agricultural land use increases mean nitrate concentrations and the occurrence of distinct winter maxima, though the latter have become markedly less pronounced since 2001. It is suggested that this improvement is a combined effect of imposition of NVZ designation in the lower reaches in 2002, animal number declines associated with the Foot & Mouth outbreak in the region in 2001, and the impact of farmers' responses to increasing fertilizer prices and to beneficial pollutant mineral N inputs from the atmosphere. Minima in nitrate-N concentrations in summer have become much less pronounced over the past decade and are typically ca. 60% higher in concentration than a decade earlier. This probably is attributable to the effects of pollutant-N leaching to depths in soil below the rooting zone when near surface biotic uptake is low in winter. The resultant N mineralization in summer enhances summer nitrate leaching. The Derwent is a relatively clean river; however, its entire catchment was designated justifiably as a NVZ in January 2009, apparently based upon a projected 95 percentile nitrate-N concentration >11.29 mg l(-1) for 2010 based upon forward projection of data from 1990 to 2004 for Derwent Bridge. A survey of water quality in March 2009 showed that some agricultural areas are still making a significant contribution to the total nitrate level well downstream, at the point responsible for implementation of

  20. The changing trend in nitrate concentrations in major aquifers due to historical nitrate loading from agricultural land across England and Wales from 1925 to 2150.

    PubMed

    Wang, L; Stuart, M E; Lewis, M A; Ward, R S; Skirvin, D; Naden, P S; Collins, A L; Ascott, M J

    2016-01-15

    Nitrate is necessary for agricultural productivity, but can cause considerable problems if released into aquatic systems. Agricultural land is the major source of nitrates in UK groundwater. Due to the long time-lag in the groundwater system, it could take decades for leached nitrate from the soil to discharge into freshwaters. However, this nitrate time-lag has rarely been considered in environmental water management. Against this background, this paper presents an approach to modelling groundwater nitrate at the national scale, to simulate the impacts of historical nitrate loading from agricultural land on the evolution of groundwater nitrate concentrations. An additional process-based component was constructed for the saturated zone of significant aquifers in England and Wales. This uses a simple flow model which requires modelled recharge values, together with published aquifer properties and thickness data. A spatially distributed and temporally variable nitrate input function was also introduced. The sensitivity of parameters was analysed using Monte Carlo simulations. The model was calibrated using national nitrate monitoring data. Time series of annual average nitrate concentrations along with annual spatially distributed nitrate concentration maps from 1925 to 2150 were generated for 28 selected aquifer zones. The results show that 16 aquifer zones have an increasing trend in nitrate concentration, while average nitrate concentrations in the remaining 12 are declining. The results are also indicative of the trend in the flux of groundwater nitrate entering rivers through baseflow. The model thus enables the magnitude and timescale of groundwater nitrate response to be factored into source apportionment tools and to be taken into account alongside current planning of land-management options for reducing nitrate losses. PMID:26546765

  1. Modelling temporal trends of 137Cs and 99Tc concentrations in Fucus vesiculosus from the eastern Irish coastline.

    PubMed

    Cournane, S; Vintró, L León; Mitchell, P I; McMahon, C A; Smith, K; Long, S

    2011-11-01

    Time series of 137Cs and 99Tc activity concentrations in the brown seaweed Fucus vesiculosus and seawater, gathered at three locations on the eastern Irish coastline during the period 1988-2008, have been modelled using a novel approach incorporating a variable uptake rate in the seaweed. Seasonal variations in the time series, identified using spectral analysis, were incorporated into the model which was used to determine transfer kinetic parameters and to predict 137Cs and 99Tc concentrations in seaweed, as influenced by levels in ambient seawater. An optimisation method combining evolutionary and grid search minimisation techniques was adopted to determine the best values for the model parameters, from which concentration factors (CF) and biological half-lives (tb1/2) for 137Cs and 99Tc in F. vesiculosus were calculated. CF values of 170-179 and 1.1×105 l kg(-1) (dry weight) were obtained for 137Cs and 99Tc, respectively, while the corresponding tb1/2 values were 39-47 and 32 days, respectively.

  2. Trends in emissions and concentrations of air pollutants in the lower troposphere in the Baltimore/Washington airshed from 1997 to 2011

    NASA Astrophysics Data System (ADS)

    He, H.; Stehr, J. W.; Hains, J. C.; Krask, D. J.; Doddridge, B. G.; Vinnikov, K. Y.; Canty, T. P.; Hosley, K. M.; Salawitch, R. J.; Worden, H. M.; Dickerson, R. R.

    2013-08-01

    Trends in the composition of the lower atmosphere (0-1500 m altitude) and surface air quality over the Baltimore/Washington area and surrounding states were investigated for the period from 1997 to 2011. We examined emissions of ozone precursors from monitors and inventories as well as ambient ground-level and aircraft measurements to characterize trends in air pollution. The US EPA Continuous Emissions Monitoring System (CEMS) program reported substantial decreases in emission of summertime nitrogen oxides (NOx) from power plants, up to ∼80% in the mid-Atlantic States. These large reductions in emission of NOx are reflected in a sharp decrease of ground-level concentrations of NOx starting around 2003. The decreasing trend of tropospheric column CO observed by aircraft is ∼0.8 Dobson unit (DU) per year, corresponding to ∼35 ppbv yr-1 in the lower troposphere (the surface to 1500 m above ground level). Satellite observations of long-term, near-surface CO show a ∼40% decrease over western Maryland between 2000 and 2011; the same magnitude is indicated by aircraft measurements above these regions upwind of the Baltimore/Washington airshed. With decreasing emissions of ozone precursors, the ground-level ozone in the Baltimore/Washington area shows a 0.6 ppbv yr-1 decrease in the past 15 yr. Since photochemical production of ozone is substantially influenced by ambient temperature, we introduce the climate penalty factor (CPF) into the trend analysis of long-term aircraft measurements. After compensating for inter-annual variations in temperature, historical aircraft measurements indicate that the daily net production of tropospheric ozone over the Baltimore/Washington area decreased from ∼20 ppbv day-1 in the late 1990s to ∼7 ppbv day-1 in the early 2010s during ozone season. A decrease in the long-term column ozone is observed as ∼0.2 DU yr-1 in the lowest 1500 m, corresponding to an improvement of ∼1.3 ppbv yr-1. Our aircraft

  3. Trends in concentrations of polychlorinated biphenyls in fish tissue from selected sites in the Delaware River basin in New Jersey, New York, and Pennsylvania, 1969-98

    USGS Publications Warehouse

    Riva-Murray, Karen; Brightbill, Robin A.; Bilger, Michael D.

    2003-01-01

    Trends in concentrations of polychlorinated biphenyls in fish tissue from selected sites in the Delaware River basin in New Jersey, New York, and Pennsylvania, 1969-98 by Karen Riva-Murray, Robin A. Brightbill, and Michael D. Bilger U.S. GEOLOGICAL SURVEY Water-Resources Investigations Report 01-4066 ABSTRACT Polychlorinated biphenyl (PCB) concentrations in fish tissue collected during the 1990's from selected sites in the Delaware River Basin were compared with concentrations in fish tissue collected during 1969-88. Data collected by State and Federal agencies on concentrations in whole-body common carp (Cyprinus carpio) and white sucker (Catostomus commersoni), and edible portions of American eel (Anguilla rostrata), smallmouth bass (Micropterus dolomieu), and channel catfish (Ictalurus punctatus) during 1969-98 were compiled to define temporal trends in concentrations of PCBs in fish tissue from selected segments of the Delaware River, Lehigh River, Schuylkill River, and Brandywine Creek. The Delaware River in the vicinity of Trenton, New Jersey and Yardley, Pennsylvania (above the tidal influence) had the largest long-term data set among the sites considered for this study and was the only site with sufficient data for statistical analysis. A general pattern of decline in PCB concentrations during 1969-98 was apparent for this river segment. PCB concentrations in whole-body white sucker from this lower Delaware River segment declined during 1969-98 from a highest concentration of 7 micrograms per gram (?g/g, wet weight) in a sample collected during 1972 to 0.26 ?g/g (wet weight) in a sample collected during 1998. PCB concentration was negatively correlated with year (Spearman rank correlation -0.46, p < 0.08, n = 15); especially after removal of a sample from 1977 with an unusually low concentration (Spearman rank correlation -0.53, p = 0.05, n = 14). PCB concentrations in edible flesh of American eel declined during 1975-95, from a highest concentration of 3

  4. 10 Yr Spatial and Temporal Trends of PM2.5 Concentrations in the Southeastern US Estimated Using High-resolution Satellite Data

    NASA Technical Reports Server (NTRS)

    Hu, X.; Waller, L. A.; Lyapustin, A.; Wang, Y.; Liu, Y.

    2013-01-01

    Long-term PM2.5 exposure has been reported to be associated with various adverse health outcomes. However, most ground monitors are located in urban areas, leading to a potentially biased representation of the true regional PM2.5 levels. To facilitate epidemiological studies, accurate estimates of spatiotemporally continuous distribution of PM2.5 concentrations are essential. Satellite-retrieved aerosol optical depth (AOD) has been widely used for PM2.5 concentration estimation due to its comprehensive spatial coverage. Nevertheless, an inherent disadvantage of current AOD products is their coarse spatial resolutions. For instance, the spatial resolutions of the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Multiangle Imaging SpectroRadiometer (MISR) are 10 km and 17.6 km, respectively. In this paper, a new AOD product with 1 km spatial resolution retrieved by the multi-angle implementation of atmospheric correction (MAIAC) algorithm was used. A two-stage model was developed to account for both spatial and temporal variability in the PM2.5-AOD relationship by incorporating the MAIAC AOD, meteorological fields, and land use variables as predictors. Our study area is in the southeastern US, centered at the Atlanta Metro area, and data from 2001 to 2010 were collected from various sources. The model was fitted for each year individually, and we obtained model fitting R2 ranging from 0.71 to 0.85, MPE from 1.73 to 2.50 g m3, and RMSPE from 2.75 to 4.10 g m3. In addition, we found cross validation R2 ranging from 0.62 to 0.78, MPE from 2.00 to 3.01 g m3, and RMSPE from 3.12 to 5.00 g m3, indicating a good agreement between the estimated and observed values. Spatial trends show that high PM2.5 levels occurred in urban areas and along major highways, while low concentrations appeared in rural or mountainous areas. A time series analysis was conducted to examine temporal trends of PM2.5 concentrations in the study area from 2001 to 2010. The results showed

  5. Multiscale modeling of multi-decadal trends in air pollutant concentrations and their radiative properties: the role of models in an integrated observing system

    NASA Astrophysics Data System (ADS)

    Mathur, R.; Xing, J.; Szykman, J.; Gan, C. M.; Hogrefe, C.; Pleim, J. E.

    2015-12-01

    Air Pollution simulation models must address the increasing complexity arising from new model applications that treat multi-pollutant interactions across varying space and time scales. Setting and attaining lower ambient air quality standards requires an improved understanding and quantification of source attribution amongst the multiple anthropogenic and natural sources, on time scales ranging from episodic to annual and spatial scales ranging from urban to continental. Changing emission patterns over the developing regions of the world are likely to exacerbate the impacts of long-range pollutant transport on background pollutant levels, which may then impact the attainment of local air quality standards. Thus, strategies for reduction of pollution levels of surface air over a region are complicated not only by the interplay of local emissions sources and several complex physical, chemical, dynamical processes in the atmosphere, but also hemispheric background levels of pollutants. Additionally, as short-lived climate forcers, aerosols and ozone exert regionally heterogeneous radiative forcing and influence regional climate trends. EPA's coupled WRF-CMAQ modeling system is applied over a domain encompassing the northern hemisphere for the period spanning 1990-2010. This period has witnessed significant reductions in anthropogenic emissions in North America and Europe as a result of implementation of control measures and dramatic increases across Asia associated with economic and population growth, resulting in contrasting trends in air pollutant distributions and transport patterns across the northern hemisphere. Model results (trends in pollutant concentrations, optical and radiative characteristics) across the northern hemisphere are analyzed in conjunction with surface, aloft and remote sensing measurements to contrast the differing trends in air pollution and aerosol-radiation interactions in these regions over the past two decades. Given the future LEO (Trop

  6. Inter-annual Variations and Decadal Trends in Surface Equatorial Pacific Phosphate Concentrations: Coral Records from the Line Islands

    NASA Astrophysics Data System (ADS)

    Sinclair, D. J.; Sherrell, R. M.; LaVigne, M.; Tudhope, A. W.; Cobb, K.

    2011-12-01

    Coralline P/Ca is a newly-calibrated proxy for oceanic phosphate concentration (LaVigne et al. 2010, Anagnostuou et al. 2011). This proxy is an important tool for reconstructing tropical ocean nutrient dynamics, especially in remote regions, such as the equatorial Pacific Ocean, which are poorly covered by instrumental records. Here we present P/Ca records in 4 Porites corals from the Line Islands in the central Equatorial Pacific spanning the last ~ 30 years. The coral from Jarvis Island (0°22'S) has a significantly higher P/Ca concentration than two independent coral records from Christmas Island (1°53'N), and a coral from Fanning Island (3°51'N). This is consistent with the strong meridional gradient in surface phosphate in the central equatorial Pacific. All corals record a long-term 2-fold decrease in phosphate concentration from the mid 1970s to the mid 1990s, in agreement with observed slowing of the Pacific Meridional Overturning Circulation (McPhadden and Zhang 2002). On inter-annual time scales, the corals all capture strong El Niño events as a decrease in surface phosphate consistent with deepening of the eastern Pacific thermocline. The magnitude of this suppression is significantly larger in the Jarvis Island coral, again consistent with its location in the high phosphate tongue in the equatorial Pacific. The Jarvis Island coral record shows hints of a decadal oscillation in P which so far does not appear to be captured by the Christmas Island coral. Further analyses are underway to extend these records and to study P dynamics in other Line Island corals. Our preliminary results suggest that Porites corals are recording P variations in the central Pacific which accord with known oceanographic changes. This study demonstrates the potential for reconstructing nutrient dynamics at annual to multidecadal resolutions. Citations LaVigne M., Matthews K. A., Grottoli A. G., Cobb K. M., Anagnostou E., Cabioch G., and Sherrell R. M. (2010) Coral skeleton P

  7. Flow-adjusted trends in dissolved selenium load and concentration in the Gunnison and Colorado Rivers near Grand Junction, Colorado, water years 1986--2008

    USGS Publications Warehouse

    Mayo, John W.; Leib, Kenneth J.

    2012-01-01

    As a result of elevated selenium concentrations, many western Colorado rivers and streams are on the U.S. Environmental Protection Agency 2010 Colorado 303(d) list, including the main stem of the Colorado River from the Gunnison River confluence to the Utah border. Selenium is a trace metal that bioaccumulates in aquatic food chains and can cause reproductive failure, deformities, and other adverse impacts in birds and fish, including several threatened and endangered fish species. Salinity in the upper Colorado River has been the focus of source-control efforts for many years. Although salinity loads and concentrations have been previously characterized at the U.S. Geological Survey (USGS) streamflow-gaging stations at the Gunnison River near Grand Junction, Colo., and at the Colorado River near the Colorado-Utah State line, trends in selenium load and concentration at these two stations have not been studied. The USGS, in cooperation with the Bureau of Reclamation and the Colorado River Water Conservation District, evaluated dissolved selenium (herein referred to as "selenium") load and concentration trends at these two sites to inform decision makers on the status and trends of selenium. This report presents results of the evaluation of trends in selenium load and concentration for two USGS streamflow-gaging stations: the Gunnison River near Grand Junction, Colo. ("Gunnison River site"), USGS site 09152500, and the Colorado River near Colorado-Utah State line ("Colorado River site"), USGS site 09163500. Flow-adjusted selenium loads were estimated for the beginning water year (WY) of the study, 1986, and the ending WY of the study, 2008. The difference between flow-adjusted selenium loads for WY 1986 and WY 2008 was selected as the method of analysis because flow adjustment removes the natural variations in load caused by changes in mean-daily streamflow, emphasizing human-caused changes in selenium load and concentration. Overall changes in human-caused effects

  8. Seasonal trends in environmental tritium concentrations in a small forest adjacent to a radioactive waste storage area

    SciTech Connect

    Amano, H. ); Garten, C.T. Jr. . Environmental Sciences Div.)

    1992-03-01

    Tritium (HTO) concentrations were studied for an entire year in a floodplain forest adjacent to a low-level radioactive solid waste storage areas (SWSA No. 5) at Oak Ridge National Laboratory (ORNL) near Oak Ridge, Tennessee, USA. Tritium in soil was the principal source of HTO to the deciduous forest. Evaporation from the surface soil along with transpiration from tree leaves both contributed to HTO in the forest atmosphere. During the growing season, transpiration was the principal contributor of HTO to the forest atmosphere, while during he dormant season, the main source of atmospheric HTO was evaporation from the surface soil. This paper discovers seasonal changes and the characteristics of vegetation which will influence the relative importance of evaporation and transpiration as sources of atmospheric HTO near the ground in temperate deciduous forests.

  9. Seasonal trends in environmental tritium concentrations in a small forest adjacent to a radioactive waste storage area

    SciTech Connect

    Amano, Hikaru ); Garten, C.T. Jr. )

    1991-01-01

    Tritium (HTO) concentrations were studied for an entire year in a floodplain forest adjacent to a low-level radioactive solid waste storage area (SWSA No. 5) at Oak Ridge National Laboratory (ORNL) near Oak Ridge, Tennessee, USA. Tritium in soil was the principal source of HTO to the deciduous forest. Evaporation from the surface soil along with transpiration from trees leaves both contributed to HTO in the forest atmosphere. During the growing season, transpiration was the principal contributor of HTO to the forest atmosphere, while during the dormant season, the main source of atmospheric HTO was evaporation from the surface soil. Seasonal changes and the characteristics of vegetation will influence the relative importance of evaporation and transpiration as sources of atmospheric HTO near the ground in temperate deciduous forests. 8 refs., 9 figs.

  10. Decadal trend of black carbon and refractory carbonaceous aerosol in the western rim of the North Pacific Ocean: atmospheric concentration and the retrieved record of deposition flux

    NASA Astrophysics Data System (ADS)

    Kaneyasu, Naoki; Yamaguchi, Takashi; Noguchi, Izumi; Akiyama, Masayuki; Matsumoto, Kiyoshi

    2013-04-01

    The long-term trend of light absorbing carbonaceous aerosols (or black carbon: BC) or refractory carbonaceous aerosol (or elemental carbon: EC) concentration is reported at European background sites such as Mace Head, and that of aerosol absorption coefficient are monitored in many GAW sites. On the contrary, such long-term data are relatively scarce at around the western part of the North Pacific Ocean. Thus, to understand the long-term variation of in the area, BC in fine aerosol fraction has been measured at Chichi-jima Islands, Japan. Chichi-jima Island is located 1000 km south of the Japanese mainland, and 1800 km west of the coast line of the Asian continent. BC has been measured with an Aethalometer (Magee, AE-16 and AE-30) since December, 1998 with 1 hr time resolution. Mass flowmeter embedded inside the Aethalometer is calibrated with a rotational dry gas-meter once a year. Monthly averaged BC concentration shows an obvious seasonal variation, i.e. high concentration during late autumn-winter-spring period resulting from the transport from East Asia, with maximum daily concentration above 500 ng m-3. In summer, daily concentration was usually less than 20 ng m-3, due to the clean background airmass originating from the North Pacific Anticyclone. Decadal trend of the annual averaged BC concentration showed a increasing trend from 2000 to 2007 and started to decrease after 2008, which roughly coincides with the reported emission trend of SO2 in China (Lu et al., 2010). In addition, total (i.e., wet + dry) deposition record of refractory carbon at two sites in the northern Japan (Rishiri Island: a remote island site, and Sapporo City: an urban site) are retrieved. At these sites, the local government have been measuring the chemical components in precipitation water collected by deposition gauges. In the deposition gauge, a membrane filter made of cellulose-acetate is fixed at the bottom of the funnel to remove water-insoluble particles from the precipitated

  11. Historical trends of concentrations, source contributions and toxicities for PAHs in dated sediment cores from five lakes in western China.

    PubMed

    Xu, Jian; Guo, Jian-Yang; Liu, Gui-Rong; Shi, Guo-Liang; Guo, Chang-Sheng; Zhang, Yuan; Feng, Yin-Chang

    2014-02-01

    In this work, sixteen U.S. EPA priority PAH compounds in the dated sediment cores were detected from five lakes in western China. In most lakes, the concentrations of the total PAHs (ΣPAHs) increased from the deep layers to the surface sediments. Two source categories, i.e. vehicular emission and biomass & domestic coal combustion were identified by Unmix, a factor analysis receptor model to explore the source contributions of PAHs in the dated sediments. The source apportionment results showed that biomass & domestic coal combustion contributed larger proportion of PAHs in the five lakes. The toxicities of PAHs in the dated sediments, assessed by BaP equivalent (BaPE) values showed that the BaPE increased gradually from the deep layers to the surface sediments in most lakes. For the first effort, the contribution of each source to BaPE was apportioned by Unmix-BaPE method, and the result indicated that the vehicular emission posed the highest toxic risk. The percentage contribution of vehicular emission for PAHs and BaPE also increased from the deep layers to the surface sediments, while biomass & domestic coal combustion exhibited the opposite tendency.

  12. The brominated flame retardants, PBDEs and HBCD, in Canadian human milk samples collected from 1992 to 2005; concentrations and trends.

    PubMed

    Ryan, John Jake; Rawn, Dorothea F K

    2014-09-01

    Human milk samples were collected from individuals residing in various regions across Canada mostly in the years 1992 to 2005. These included five large cities in southern Canada as well as samples from Nunavik in northern Quebec. Comparative samples were also collected from residents of Austin, Texas, USA in 2002 and 2004. More than 300 milk samples were analysed for the brominated flame retardants (BFRs), PBDEs and HBCD, by extraction, purification and quantification using either isotope dilution gas chromatography-mass spectrometry (GC-MS) or liquid chromatography-MS. The Canadian total PBDE values in the years 2002-2005 show median levels of about 20μg/kg on a lipid basis; a value significantly higher than in the 1980s and 1990s. Milk samples from Inuit donors in the northern region of Nunavik were slightly lower in PBDE concentrations than those from populated regions in the south of Quebec. Milk samples from Ontario contained slightly lower amounts of PBDEs in two time periods than those from Texas. HBCD levels in most milk samples were usually less than 1ppb milk lipid and dominated by the α-isomer. This large data set of BFRs in Canadian human milk demonstrates an increase in the last few decades in human exposure to BFRs which now appears to have stabilized.

  13. Seasonal trends, meteorological impacts, and associated health risks with atmospheric concentrations of gaseous pollutants at an Indian coastal city.

    PubMed

    Mahapatra, Parth Sarathi; Panda, Sipra; Walvekar, P P; Kumar, R; Das, Trupti; Gurjar, B R

    2014-10-01

    This study presents surface ozone (O3) and carbon monoxide (CO) measurements conducted at Bhubaneswar from December 2010 to November 2012 and attempts for the very first time a health risk assessment of the atmospheric trace gases. Seasonal variation in average 24 h O3 and CO shows a distinct winter (December to February) maxima of 38.98 ± 9.32 and 604.51 ± 145.91 ppbv, respectively. O3 and CO characteristics and their distribution were studied in the form of seasonal/diurnal variations, air flow patterns, inversion conditions, and meteorological parameters. The observed winter high is likely due to higher regional emissions, the presence of a shallower boundary layer, and long-range transport of pollutants from the Indo-Gangetic Plain (IGP). Large differences between daytime and nighttime O3 values during winter compared to other seasons suggest that photochemistry is much more active on this site during winter. O3 and CO observations are classified in continental and marine air masses, and continental influence is estimated to increase O3 and CO by up to 20 and 120 ppbv, respectively. Correlation studies between O3 and CO in various seasons indicated the role of CO as one of the O3 precursors. Health risk estimates predict 48 cases of total premature mortality in adults due to ambient tropospheric O3 during the study period. Comparatively low CO concentrations at the site do not lead to any health effects even during winter. This study highlights the possible health risks associated with O3 and CO pollution in Bhubaneswar, but these results are derived from point measurements and should be complemented either with regional scale observations or chemical transport models for use in design of mitigation policies.

  14. Trends in concentrations of nitrate and total dissolved solids in public supply wells of the Bunker Hill, Lytle, Rialto, and Colton groundwater subbasins, San Bernardino County, California: Influence of legacy land use

    USGS Publications Warehouse

    Kent, Robert; Landon, Matthew K.

    2013-01-01

    Concentrations and temporal changes in concentrations of nitrate and total dissolved solids (TDS) in groundwater of the Bunker Hill, Lytle, Rialto, and Colton groundwater subbasins of the Upper Santa Ana Valley Groundwater Basin were evaluated to identify trends and factors that may be affecting trends. One hundred, thirty-one public-supply wells were selected for analysis based on the availability of data spanning at least 11 years between the late 1980s and the 2000s. Forty-one of the 131 wells (31%) had a significant (p < 0.10) increase in nitrate and 14 wells (11%) had a significant decrease in nitrate. For TDS, 46 wells (35%) had a significant increase and 8 wells (6%) had a significant decrease. Slopes for the observed significant trends ranged from − 0.44 to 0.91 mg/L/yr for nitrate (as N) and − 8 to 13 mg/L/yr for TDS. Increasing nitrate trends were associated with greater well depth, higher percentage of agricultural land use, and being closer to the distal end of the flow system. Decreasing nitrate trends were associated with the occurrence of volatile organic compounds (VOCs); VOC occurrence decreases with increasing depth. The relations of nitrate trends to depth, lateral position, and VOCs imply that increasing nitrate concentrations are associated with nitrate loading from historical agricultural land use and that more recent urban land use is generally associated with lower nitrate concentrations and greater VOC occurrence. Increasing TDS trends were associated with relatively greater current nitrate concentrations and relatively greater amounts of urban land. Decreasing TDS trends were associated with relatively greater amounts of natural land use. Trends in TDS concentrations were not related to depth, lateral position, or VOC occurrence, reflecting more complex factors affecting TDS than nitrate in the study area.

  15. Trends in concentrations of nitrate and total dissolved solids in public supply wells of the Bunker Hill, Lytle, Rialto, and Colton groundwater subbasins, San Bernardino County, California: influence of legacy land use.

    PubMed

    Kent, Robert; Landon, Matthew K

    2013-05-01

    Concentrations and temporal changes in concentrations of nitrate and total dissolved solids (TDS) in groundwater of the Bunker Hill, Lytle, Rialto, and Colton groundwater subbasins of the Upper Santa Ana Valley Groundwater Basin were evaluated to identify trends and factors that may be affecting trends. One hundred, thirty-one public-supply wells were selected for analysis based on the availability of data spanning at least 11 years between the late 1980s and the 2000s. Forty-one of the 131 wells (31%) had a significant (p<0.10) increase in nitrate and 14 wells (11%) had a significant decrease in nitrate. For TDS, 46 wells (35%) had a significant increase and 8 wells (6%) had a significant decrease. Slopes for the observed significant trends ranged from -0.44 to 0.91 mg/L/yr for nitrate (as N) and -8 to 13 mg/L/yr for TDS. Increasing nitrate trends were associated with greater well depth, higher percentage of agricultural land use, and being closer to the distal end of the flow system. Decreasing nitrate trends were associated with the occurrence of volatile organic compounds (VOCs); VOC occurrence decreases with increasing depth. The relations of nitrate trends to depth, lateral position, and VOCs imply that increasing nitrate concentrations are associated with nitrate loading from historical agricultural land use and that more recent urban land use is generally associated with lower nitrate concentrations and greater VOC occurrence. Increasing TDS trends were associated with relatively greater current nitrate concentrations and relatively greater amounts of urban land. Decreasing TDS trends were associated with relatively greater amounts of natural land use. Trends in TDS concentrations were not related to depth, lateral position, or VOC occurrence, reflecting more complex factors affecting TDS than nitrate in the study area. PMID:23500406

  16. Trends in concentrations of nitrate and total dissolved solids in public supply wells of the Bunker Hill, Lytle, Rialto, and Colton groundwater subbasins, San Bernardino County, California: influence of legacy land use.

    PubMed

    Kent, Robert; Landon, Matthew K

    2013-05-01

    Concentrations and temporal changes in concentrations of nitrate and total dissolved solids (TDS) in groundwater of the Bunker Hill, Lytle, Rialto, and Colton groundwater subbasins of the Upper Santa Ana Valley Groundwater Basin were evaluated to identify trends and factors that may be affecting trends. One hundred, thirty-one public-supply wells were selected for analysis based on the availability of data spanning at least 11 years between the late 1980s and the 2000s. Forty-one of the 131 wells (31%) had a significant (p<0.10) increase in nitrate and 14 wells (11%) had a significant decrease in nitrate. For TDS, 46 wells (35%) had a significant increase and 8 wells (6%) had a significant decrease. Slopes for the observed significant trends ranged from -0.44 to 0.91 mg/L/yr for nitrate (as N) and -8 to 13 mg/L/yr for TDS. Increasing nitrate trends were associated with greater well depth, higher percentage of agricultural land use, and being closer to the distal end of the flow system. Decreasing nitrate trends were associated with the occurrence of volatile organic compounds (VOCs); VOC occurrence decreases with increasing depth. The relations of nitrate trends to depth, lateral position, and VOCs imply that increasing nitrate concentrations are associated with nitrate loading from historical agricultural land use and that more recent urban land use is generally associated with lower nitrate concentrations and greater VOC occurrence. Increasing TDS trends were associated with relatively greater current nitrate concentrations and relatively greater amounts of urban land. Decreasing TDS trends were associated with relatively greater amounts of natural land use. Trends in TDS concentrations were not related to depth, lateral position, or VOC occurrence, reflecting more complex factors affecting TDS than nitrate in the study area.

  17. Risk assessment of exposure to waterborne and airborne radon-222 in Illinois. Final report

    SciTech Connect

    Hallenbeck, W.H.

    1987-12-01

    This study analyzed epidemiological and experimental animal studies in order to develop exposure-response relationships for radon-induced cancer. These relationships were used to estimate lifetime risks and annual excess cases based on the available waterborne and airborne data for Illinois. Exceedances of the USEPA action level of 4pCi/l occurred in 13% of 303 first-floor measurements and 43% of 1094 basement measurements. For waterborne radon, the highest lifetime risk of cancer mortality associated with an Illinois groundwater-based drinking water system was estimated to be 4 x 104. The number of excess cases of fatal cancer generated per year in Illinois was estimated to be about six. For airborne radon, a tentative value of 0.9 pCi/l (for first floors), derived from the limited existing data, was used to estimate the average lifetime lung-cancer mortality risk and the number of excess cases of fatal lung cancer generated per year. The average lifetime lung-cancer mortality risk was estimated to be 0.0048, and the annual number of excess cases of fatal lung cancer was estimated to be 784. Due to the nature of the underlying exposure-response relationships for radon-induced cancer, the values presented most likely represent upper-bound estimates.

  18. Investigation of radon-222 emissions from underground uranium mines. Progress report No. 2

    SciTech Connect

    Jackson, P.O.; Glissmeyer, J.A.; Enderlin, W.I.; Schwendiman, L.C.; Wogman, N.A.; Perkins, R.W.

    1980-02-01

    A reliable estimate of radon emissions to the environment from underground uranium mines was obtained through measurements of radon in ventilation exhaust air at 24 uranium mines and estimates of radon release from ore piles and waste piles at mines and in water pumped from mines. Three additional mines sampled in 1978 but not in 1979 were included in the overall results. Total production of U/sub 3/O/sub 8/ from the mines thus far sampled represent about 63% of total 1978 US production from underground mines. Wide variation in radon emission per unit of production was shown from mine to mine; hence, it became necessary to sum all radon from all mines measured and divide by the sum of all U/sub 3/O/sub 8/ production in 1978 from these mines to arrive at a valid estimate of Ci per ton of U/sub 3/O/sub 8/. This value was found to be 26.7 per ton or 5400 Ci/RRY (182 metric tons). The radon emitted in mine ventilation air was by far the dominant source, with other than ventilation exhaust sources accounting for less than three percent of radon in ventilation exhaust. Other observations of interest in this study were the diurnal fluctuations of radon with barometric pressure and the statistically significant relationship between radon released per year from a mine and the cumulative ore production at the time of radon measurement. The linear relationship between Ci/yr of radon and cumulative ore accounted for about half the variability.Several sources of random errors and possible biases were evaluated using some simple descriptive statistics insofar as the current data permitted. Errors in air flow rate in the vents sampled, fluctuations in radon emission with time of day, counting instrument calibration and production rate were estimated and combined to give an uncertainty of about +- 24 percent at the 95 percent confidence level.

  19. Long-term trends in United States highway emissions, ambient concentrations, and in-vehicle exposure to carbon monoxide in traffic.

    PubMed

    Flachsbart, P G

    1995-01-01

    This paper reviews 16 published studies conducted between 1965 and 1992 of in-vehicle exposure to carbon monoxide (CO) in traffic on urban roadways in the United States. Analysis of these studies shows a downward trend in CO exposure, which corresponds to similar trends for CO in motor vehicle emission factors and ambient concentrations. The analysis demonstrates that emission controls on motor vehicles sold in the United States have been very effective in reducing commuter CO exposure. It is recommended that future studies of this kind be done routinely in cities nationwide to provide a more robust database for accurate estimates of commuter exposure. Such studies should relate human exposure measurements to estimates of emissions at study sites to document the progress of motor vehicle emission control programs. In addition, future studies should use standard protocols to enable comparisons of results in time and space. Previous studies have shown that typical in-vehicle exposures vary by study approach (direct versus indirect), city, season, roadway type and location, travel mode, and vehicular ventilation. Future studies should carefully account for these factors. PMID:8938245

  20. Long-term trends in United States highway emissions, ambient concentrations, and in-vehicle exposure to carbon monoxide in traffic.

    PubMed

    Flachsbart, P G

    1995-01-01

    This paper reviews 16 published studies conducted between 1965 and 1992 of in-vehicle exposure to carbon monoxide (CO) in traffic on urban roadways in the United States. Analysis of these studies shows a downward trend in CO exposure, which corresponds to similar trends for CO in motor vehicle emission factors and ambient concentrations. The analysis demonstrates that emission controls on motor vehicles sold in the United States have been very effective in reducing commuter CO exposure. It is recommended that future studies of this kind be done routinely in cities nationwide to provide a more robust database for accurate estimates of commuter exposure. Such studies should relate human exposure measurements to estimates of emissions at study sites to document the progress of motor vehicle emission control programs. In addition, future studies should use standard protocols to enable comparisons of results in time and space. Previous studies have shown that typical in-vehicle exposures vary by study approach (direct versus indirect), city, season, roadway type and location, travel mode, and vehicular ventilation. Future studies should carefully account for these factors.

  1. Analysis and comparison of trends in concentrations and emissions of VOC and CO and VOC:CO ratios in urban European cities

    NASA Astrophysics Data System (ADS)

    D'Angiola, A.; von Schneidemesser, E.; Granier, C.; Law, K.; Monks, P. S.

    2010-12-01

    approach to compare emissions ratios between NMHC and CO for the megacities region of Paris and London and to compare these trends with measured ambient concentrations from three monitoring sites: Eltham (L) suburban station, Marylebone Road (L) kerbside station and Les Halles (P) urban station for the period 1997-2006.

  2. A statistical evaluation of the influence of housing characteristics and geogenic radon potential on indoor radon concentrations in France.

    PubMed

    Demoury, C; Ielsch, G; Hemon, D; Laurent, O; Laurier, D; Clavel, J; Guillevic, J

    2013-12-01

    Radon-222 is a radioactive natural gas produced by the decay of radium-226, known to be the main contributor to natural background radiation exposure. Effective risk management needs to determine the areas in which the density of buildings with high radon levels is likely to be highest. Predicting radon exposure from the location and characteristics of a dwelling could also contribute to epidemiological studies. Beginning in the nineteen-eighties, a national radon survey consisting in more than 10,000 measurements of indoor radon concentrations was conducted in French dwellings by the Institute for Radiological Protection and Nuclear Safety (IRSN). Housing characteristics, which may influence radon accumulation in dwellings, were also collected. More recently, the IRSN generated a French geogenic radon potential map based on the interpretation of geological features. The present study analyzed the two datasets to investigate the factors influencing indoor radon concentrations using statistical modeling and to determine the optimum use of the information on geogenic radon potential that showed the best statistical association with indoor radon concentration. The results showed that the variables associated with indoor radon concentrations were geogenic radon potential, building material, year of construction, foundation type, building type and floor level. The model, which included the surrounding geogenic radon potential (i.e. the average geogenic radon potential within a disc of radius 20 km centered on the indoor radon measurement point) and variables describing house-specific factors and lifestyle explained about 20% of the overall variability of the logarithm of radon concentration. The surrounding geogenic radon potential was fairly closely associated with the local average indoor radon concentration. The prevalence of exposure to radon above specific thresholds and the average exposures to radon clearly increased with increasing classes of geogenic radon

  3. Mean annual (222)Rn concentration in homes located in different geological regions of Poland: first approach to whole country area.

    PubMed

    Przylibski, Tadeusz A; Zebrowski, Adam; Karpińska, Maria; Kapała, Jacek; Kozak, Krzysztof; Mazur, Jadwiga; Grządziel, Dominik; Mamont-Cieśla, Kalina; Stawarz, Olga; Kozłowska, Beata; Kłos, Barbara; Dorda, Jerzy; Wysocka, Małgorzata; Olszewski, Jerzy; Dohojda, Marek

    2011-08-01

    The paper presents the results of year-long measurements of radon ((222)Rn) concentration inside 129 buildings in Poland in relation to the geological conditions of their foundation. The authors took into account the division of the country into tectonic units, as well as the lithology of the rocks forming the bedrock of these buildings. As expected, the highest value of mean annual (222)Rn concentration (845 Bq/m(3)) was recorded in a building situated in the area of the Sudetes, while the highest geometric mean (characteristic of the expected log-normal data distribution) was calculated based on measurements from buildings located within the East-European craton, in the area of Mazury-Podlasie monocline, where it reached 231 Bq/m(3). Such results reflect geological conditions - the occurrence of crystalline rocks (especially U- and Ra-enriched granites and orthogneisses) on the surface in the Sudetes, and of young post-glacial sediments containing fragments of Scandinavian crystalline rocks, also enriched with U and Ra, in the area of Mazury-Podlasie monocline. However, the least expected result of the investigations was finding out that, contrary to the hitherto widespread belief, none of the major tectonic units of Poland can be excluded from the list of those containing buildings with mean annual (222)Rn concentration exceeding 200 Bq/m(3). The mean annual concentration of radon for all the buildings were much higher than the mean concentration value (49.1 Bq/m(3)) of indoor radon in Poland quoted so far. These results cast a completely new light on the necessity to perform measurements of radon concentration in residential buildings in Poland, no more with reference to small areas with outcrops of crystalline rocks (especially the Sudetes, being the Polish fragment of the European Variscan belt), but for all the major tectonic units within Poland. PMID:21555169

  4. Concentrations of 222Rn, 220Rn and their decay products measured in outdoor air in various rural zones (Morocco) by using solid-state nuclear track detectors and resulting radiation dose to the rural populations.

    PubMed

    Misdaq, M A; Amrane, M; Ouguidi, J

    2010-03-01

    Alpha and beta activities per unit volume of air due to radon ((222)Rn), thoron ((220)Rn) and their progenies were measured in the outdoor air at different locations in Morocco by using both CR-39 and LR-115 type II solid-state nuclear track detectors (SSNTDs). In addition, the radon concentration was continuously measured in one location by using the methods with SSNTDs and AlphaGuard counter. The influence of the geological and meteorological conditions as well as phosphate and building material dust on the radon concentration in the outdoor air of the areas studied was investigated. The committed equivalent doses due to (218)Po and (214)Po radon short-lived progeny were evaluated in different tissues of the respiratory tract of the members of the public from the inhalation of outdoor air. The annual effective dose due to radon short-lived progeny from the inhalation of outdoor air by the members of the rural population was estimated. PMID:19887516

  5. 10-year spatial and temporal trends of PM2.5 concentrations in the southeastern US estimated using high-resolution satellite data

    NASA Astrophysics Data System (ADS)

    Hu, X.; Waller, L. A.; Lyapustin, A.; Wang, Y.; Liu, Y.

    2014-06-01

    Long-term PM2.5 exposure has been associated with various adverse health outcomes. However, most ground monitors are located in urban areas, leading to a potentially biased representation of true regional PM2.5 levels. To facilitate epidemiological studies, accurate estimates of the spatiotemporally continuous distribution of PM2.5 concentrations are important. Satellite-retrieved aerosol optical depth (AOD) has been increasingly used for PM2.5 concentration estimation due to its comprehensive spatial coverage. Nevertheless, previous studies indicated that an inherent disadvantage of many AOD products is their coarse spatial resolution. For instance, the available spatial resolutions of the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Multiangle Imaging SpectroRadiometer (MISR) AOD products are 10 and 17.6 km, respectively. In this paper, a new AOD product with 1 km spatial resolution retrieved by the multi-angle implementation of atmospheric correction (MAIAC) algorithm based on MODIS measurements was used. A two-stage model was developed to account for both spatial and temporal variability in the PM2.5-AOD relationship by incorporating the MAIAC AOD, meteorological fields, and land use variables as predictors. Our study area is in the southeastern US centered at the Atlanta metro area, and data from 2001 to 2010 were collected from various sources. The model was fitted annually, and we obtained model fitting R2 ranging from 0.71 to 0.85, mean prediction error (MPE) from 1.73 to 2.50 μg m-3, and root mean squared prediction error (RMSPE) from 2.75 to 4.10 μg m-3. In addition, we found cross-validation R2 ranging from 0.62 to 0.78, MPE from 2.00 to 3.01 μg m-3, and RMSPE from 3.12 to 5.00 μg m-3, indicating a good agreement between the estimated and observed values. Spatial trends showed that high PM2.5 levels occurred in urban areas and along major highways, while low concentrations appeared in rural or mountainous areas. Our time

  6. Spatiotemporal variation of radon and carbon dioxide concentrations in an underground quarry: coupled processes of natural ventilation, barometric pumping and internal mixing.

    PubMed

    Perrier, Frédéric; Richon, Patrick

    2010-04-01

    Radon-222 and carbon dioxide concentrations have been measured during several years at several points in the atmosphere of an underground limestone quarry located at a depth of 18 m in Vincennes, near Paris, France. Both concentrations showed a seasonal cycle. Radon concentration varied from 1200 to 2000 Bq m(-3) in summer to about 800-1400 Bq m(-3) in winter, indicating winter ventilation rates varying from 0.6 to 2.5 x 10(-6) s(-1). Carbon dioxide concentration varied from 0.9 to 1.0% in summer, to about 0.1-0.3% in winter. Radon concentration can be corrected for natural ventilation using temperature measurements. The obtained model also accounts for the measured seasonal variation of carbon dioxide. After correction, radon concentrations still exhibit significant temporal variation, mostly associated with the variation of atmospheric pressure, with coupling coefficients varying from -7 to -26 Bq m(-3) hPa(-1). This variation can be accounted for using a barometric pumping model, coupled with natural ventilation in winter, and including internal mixing as well. After correction, radon concentrations exhibit residual temporal variation, poorly correlated between different points, with standard deviations varying from 3 to 6%. This study shows that temporal variation of radon concentrations in underground cavities can be understood to a satisfactory level of detail using non-linear and time-dependent modelling. It is important to understand the temporal variation of radon concentrations and the limitations in their modelling to monitor the properties of natural or artificial underground settings, and to be able to assess the existence of new processes, for example associated with the preparatory phases of volcanic eruptions or earthquakes.

  7. Trends in nutrient concentrations, loads, and yields in streams in the Sacramento, San Joaquin, and Santa Ana Basins, California, 1975-2004

    USGS Publications Warehouse

    Kratzer, Charles R.; Kent, Robert; Seleh, Dina K.; Knifong, Donna L.; Dileanis, Peter D.; Orlando, James L.

    2011-01-01

    San Joaquin Basin but decreased in the Sacramento and Santa Ana Basins from 1982 to 2002. Tile drainage accounted for 22 percent of the total nitrogen load in the San Joaquin River near Vernalis for 1985-2004. Nutrient loads and trends were calculated by using the log-linear multiple-regression model, LOADEST. Loads were calculated for water years 1975-2004 for 22 sites in the Sacramento Basin, 15 sites in the San Joaquin Basin, and 6 sites in the Santa Ana Basin. The average annual load of total nitrogen and total phosphorus for 1985-2004 in subbasins in the Sacramento and San Joaquin Basins were divided by their drainage areas to calculate average annual yield. Total nitrogen yields were greater than 2.45 tons per square mile per year [(tons/mi2)/yr] in about 61 percent of the valley floor in the San Joaquin Basin compared with only about 12 percent of the valley floor in the Sacramento Basin. Total phosphorus yields were greater than 0.34 (tons/mi2)/yr in about 43 percent of the valley floor in the San Joaquin Basin compared with only about 5 percent in the valley floor of the Sacramento Basin. In a stepwise multiple linear-regression analysis of 30 subbasins in the Sacramento and San Joaquin Basins, the most important explanatory variables (out of 11 variables) for the response variable (total nitrogen yield) were the percentage of land use in (1) orchards and vineyards, (2) row crops, and (3) urban categories. For total phosphorus yield, the most important explanatory variable was the amount of fertilizer application plus manure production. Trends were evaluated for three time periods: 1975-2004, 1985-2004, and 1993-2004. Most trends in flow-adjusted concentrations of nutrients in the Sacramento Basin were downward for all three time periods. The decreasing nutrient trends in the American River at Sacramento and the Sacramento River at Freeport for 1975-2004 were attributed to the consolidation of wastewater in the Sacramento metropolitan area in December 1982 to

  8. Personal Breathing Zone Exposures among Hot-Mix Asphalt Paving Workers; Preliminary Analysis for Trends and Analysis of Work Practices That Resulted in the Highest Exposure Concentrations

    PubMed Central

    Osborn, Linda V.; Snawder, John E.; Kriech, Anthony J.; Cavallari, Jennifer M.; McClean, Michael D.; Herrick, Robert F.; Blackburn, Gary R.; Olsen, Larry D.

    2015-01-01

    An exposure assessment of hot-mix asphalt (HMA) paving workers was conducted to determine which of four exposure scenarios impacted worker exposure and dose. Goals of this report are to present the personal-breathing zone (PBZ) data, discuss the impact of substituting the releasing/cleaning agent, and discuss work practices that resulted in the highest exposure concentration for each analyte. One-hundred-seven PBZ samples were collected from HMA paving workers on days when diesel oil was used as a releasing/cleaning agent. An additional 36 PBZ samples were collected on days when B-100 (100% biodiesel, containing no petroleum-derived products) was used as a substitute releasing/cleaning agent. Twenty-four PBZ samples were collected from a reference group of concrete workers, who also worked in outdoor construction but had no exposure to asphalt emissions. Background and field blank samples were also collected daily. Total particulates and the benzene soluble fraction were determined gravimetrically. Total organic matter was determined using gas chromatography (GC) with flame ionization detection and provided qualitative information about other exposure sources contributing to worker exposure besides asphalt emissions. Thirty-three individual polycyclic aromatic compounds (PACs) were determined using GC with time-offlight mass spectrometry; results were presented as either the concentration of an individual PAC or a summation of the individual PACs containing either 2- to 3-rings or 4- to 6-rings. Samples were also screened for PACs containing 4- to 6-rings using fluorescence spectroscopy. Arithmetic means, medians, and box plots of the PBZ data were used to evaluate trends in the data. Box plots illustrating the diesel oil results were more variable than the B-100. Also, the highest diesel oil results were much higher in concentration than the highest B-100 results. An analysis of the highest exposure results and field notes revealed a probable association between

  9. Concentrations and loads of suspended sediment and nutrients in surface water of the Yakima River basin, Washington, 1999-2000 [electronic resource] : with an analysis of trends in concentrations

    USGS Publications Warehouse

    Ebbert, James C.; Embrey, Sandra S.; Kelley, Janet A.

    2003-01-01

    Spatial and temporal variations in concentrations and loads of suspended sediment and nutrients in surface water of the Yakima River Basin were assessed using data collected during 1999?2000 as part of the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Program. Samples were collected at 34 sites located throughout the Basin in August 1999 using a Lagrangian sampling design, and also were collected weekly and monthly from May 1999 through January 2000 at three of the sites. Nutrient and sediment data collected at various time intervals from 1973 through 2001 by the USGS, Bureau of Reclamation, Washington State Department of Ecology, and Roza-Sunnyside Board of Joint Control were used to assess trends in concentrations. During irrigation season (mid-March to mid-October), concentrations of suspended sediment and nutrients in the Yakima River increase as relatively pristine water from the forested headwaters moves downstream and mixes with discharges from streams, agricultural drains, and wastewater treatment plants. Concentrations of nutrients also depend partly on the proportions of mixing between river water and discharges: in years of ample water supply in headwater reservoirs, more water is released during irrigation season and there is more dilution of nutrients discharged to the river downstream. For example, streamflow from river mile (RM) 103.7 to RM 72 in August 1999 exceeded streamflow in July 1988 by a factor of almost 2.5, but loads of total nitrogen and phosphorus discharged to the reach from streams, drains, and wastewater treatment plants were only 1.2 and 1.1 times larger. In years of ample water supply, canal water, which is diverted from either the Yakima or Naches River, makes up more of the flow in drains and streams carrying agricultural return flows. The canal water dilutes nutrients (especially nitrate) transported to the drains and streams in runoff from fields and in discharges from subsurface field drains and the

  10. Nutrient and suspended-sediment concentrations, trends, loads, and yields from the nontidal part of the Susquehanna, Potomac, Patuxent, and Choptank rivers, 1985-96

    USGS Publications Warehouse

    Darrell, Linda C.; Majedi, Brenda F.; Lizarraga, Joy S.; Blomquist, Joel D.

    1999-01-01

    The Chesapeake Bay River-Input Monitoring Program was established to characterize the water quality of four major rivers in Maryland, and to quantify the load and the long-term trends in concentrations of nutrients (nitrogen and phosphorus) and suspended sediment transported from the nontidal part of each river to the Chesapeake Bay. As part of the River-Input Monitoring Program, nutrient and suspended-sediment data and streamflow data were collected from 1985 through 1996 at the Susquehanna, Potomac, Patuxent, and Choptank Rivers above the points of tidal influence. The data were used to determine the effectiveness of strategies aimed at reducing nutrients entering Chesapeake Bay from its tributaries. Of the four rivers studied, the Patuxent River had the highest median concentrations of total nitrogen (2.6 milligrams per liter), total phosphorus (0.17 milligrams per liter), and suspended sediment (45 milligrams per liter) during the 12-year period. From 1985?96, flow-adjusted concentrations of total nitrogen decreased in all but the Potomac River, flow-adjusted concentrations of total phosphorus decreased in all four rivers, and flow-adjusted concentrations of suspended sediment decreased in all but the Susquehanna River. The rivers that contributed the greatest amount of streamflow to Chesapeake Bay, the Susquehanna and Potomac, also contributed the greatest nutrient loads and suspended-sediment loads to the Bay. The Susquehanna River transported the highest average-annual loads of total phosphorus (4.7 million pounds per year) and total nitrogen (146 million pounds per year), while the Potomac River transported the highest average-annual load of suspended sediment (4.1 billion pounds per year) to the Bay. Annual loads and annual mean streamflow were normalized by basin drainage area to account for some of the hydrologic differences among the river basins. An increase in precipitation from south to north is still apparent, however, when comparing the water

  11. Inter-annual trend of the primary contribution of ship emissions to PM2.5 concentrations in Venice (Italy): Efficiency of emissions mitigation strategies

    NASA Astrophysics Data System (ADS)

    Contini, Daniele; Gambaro, Andrea; Donateo, Antonio; Cescon, Paolo; Cesari, Daniela; Merico, Eva; Belosi, Franco; Citron, Marta

    2015-02-01

    Ships and harbour emissions are currently increasing, due to the increase of tourism and trade, with potential impact on global air pollution and climate. At local scale, in-port ship emissions influence air quality in coastal areas impacting on health of coastal communities. International legislations to reduce ship emissions, both at Worldwide and European levels, are mainly based on the use of low-sulphur content fuel. In this work an analysis of the inter-annual trends of primary contribution, ε, of tourist shipping to the atmospheric PM2.5 concentrations in the urban area of Venice has been performed. Measurements have been taken in the summer periods of 2007, 2009 and 2012. Results show a decrease of ε from 7% (±1%) in 2007 to 5% (±1%) in 2009 and to 3.5% (±1%) in 2012. The meteorological and micrometeorological conditions of the campaigns were similar. Tourist ship traffic during measurement campaigns increased, in terms of gross tonnage, of about 25.4% from 2007 to 2009 and of 17.6% from 2009 to 2012. The decrease of ε was associated to the effect of a voluntary agreement (Venice Blue Flag) for the use of low-sulphur content fuel enforced in the area between 2007 and 2009 and to the implementation of the 2005/33/CE Directive in 2010. Results show that the use of low-sulphur fuel could effectively reduce the impact of shipping to atmospheric primary particles at local scale. Further, voluntary agreement could also be effective in reducing the impact of shipping on local air quality in coastal areas.

  12. Estimation of background CO2 concentrations at the high alpine station Schneefernerhaus by atmospheric observations and inverse modelling

    NASA Astrophysics Data System (ADS)

    Giemsa, Esther; Jacobeit, Jucundus; Ries, Ludwig; Frank, Gabriele; Hachinger, Stephan; Meyer-Arnek, Julian

    2016-04-01

    In order to estimate the influence of Central European CO2 emissions, a new method to retrieve background concentrations based on statistics of radon-222 and backward trajectories is developed and applied to the CO2 observations at the alpine high-altitude research station Schneefernerhaus (2670 m a.s.l.). The reliable identification of baseline conditions is important for perceiving changes in time as well as in the sources and sinks of greenhouse gases and thereby assessing the efficiency of existing mitigation strategies. In the particular case of Central Europe, the analysis of background concentrations could add further insights on the question why background CO2 concentrations increased in the last few decades, despite a significant decrease in the reported emissions. Ongoing effort to define the baseline conditions has led to a variety of data selection techniques. In this diversity of data filtering concepts, a relatively recent data selection method effectively appropriates observations of radon-222 to reliably and unambiguously identify baseline air masses. Owing to its relatively constant emission rate from the ice-free land surface and its half-life of 3.8 days that is solely achieved through radioactive decay, the tropospheric background concentration of the inert radioactive gas is low and temporal variations caused by changes in atmospheric transport are precisely detectable. For defining the baseline air masses reaching the high alpine research station Schneefernerhaus, an objective analysis approach is applied to the two-hourly radon records. The CO2 values of days by the radon method associated with prevailing atmospheric background conditions result in the CO2 concentrations representing the least land influenced air masses. Additionally, three-dimensional back-trajectories were retrieved using the Lagrangian Particle Dispersion Model (LPDM) FLEXPART driven by analysis fields of the Global Forecast System (GFS) produced by the National Centers

  13. Attached, unattached fraction of progeny concentrations and equilibrium factor for dose assessments from (222)Rn and (220)Rn.

    PubMed

    Singh, Parminder; Saini, Komal; Mishra, Rosaline; Sahoo, Bijay Kumar; Bajwa, Bikramjit Singh

    2016-08-01

    In this study, measurements of indoor radon ((222)Rn), thoron ((220)Rn) and their equilibrium equivalent concentration (EEC) were carried out in 96 dwellings from 22 different villages situated in Hamirpur district, Himachal Pradesh, India, by using LR-115 type II-based pinhole twin cup dosimeters and deposition-based progeny sensors (DRPS/DTPS). The annual average indoor (222)Rn and (220)Rn concentrations observed in these dwellings were 63.82 and 89.59 Bq/m(3), respectively, while the average EEC (attached + unattached) for (222)Rn and (220)Rn was 29.28 and 2.74 Bq/m(3). For (222)Rn (f Rn) and (220)Rn (f Tn), the average values of unattached fraction were 0.11 and 0.09, respectively. The equilibrium factors for radon (F Rn) and thoron (F Tn) varied from 0.12 to 0.77 with an average of 0.50, and from 0.01 to 0.34 with an average of 0.05, respectively. The annual inhalation dose due to mouth and nasal breathing was calculated using dose conversion factors and unattached fractions. The indoor annual effective doses for (222)Rn (AEDR) and (220)Rn (AEDT) were found to be 1.92 and 0.83 mSv a(-1), respectively. The values of (222)Rn/(220)Rn concentrations and annual effective doses obtained in the present study are within the safe limits as recommended by the International Commission on Radiological Protection for indoor dwelling exposure conditions. PMID:27289385

  14. Attached, unattached fraction of progeny concentrations and equilibrium factor for dose assessments from (222)Rn and (220)Rn.

    PubMed

    Singh, Parminder; Saini, Komal; Mishra, Rosaline; Sahoo, Bijay Kumar; Bajwa, Bikramjit Singh

    2016-08-01

    In this study, measurements of indoor radon ((222)Rn), thoron ((220)Rn) and their equilibrium equivalent concentration (EEC) were carried out in 96 dwellings from 22 different villages situated in Hamirpur district, Himachal Pradesh, India, by using LR-115 type II-based pinhole twin cup dosimeters and deposition-based progeny sensors (DRPS/DTPS). The annual average indoor (222)Rn and (220)Rn concentrations observed in these dwellings were 63.82 and 89.59 Bq/m(3), respectively, while the average EEC (attached + unattached) for (222)Rn and (220)Rn was 29.28 and 2.74 Bq/m(3). For (222)Rn (f Rn) and (220)Rn (f Tn), the average values of unattached fraction were 0.11 and 0.09, respectively. The equilibrium factors for radon (F Rn) and thoron (F Tn) varied from 0.12 to 0.77 with an average of 0.50, and from 0.01 to 0.34 with an average of 0.05, respectively. The annual inhalation dose due to mouth and nasal breathing was calculated using dose conversion factors and unattached fractions. The indoor annual effective doses for (222)Rn (AEDR) and (220)Rn (AEDT) were found to be 1.92 and 0.83 mSv a(-1), respectively. The values of (222)Rn/(220)Rn concentrations and annual effective doses obtained in the present study are within the safe limits as recommended by the International Commission on Radiological Protection for indoor dwelling exposure conditions.

  15. seawaveQ: an R package providing a model and utilities for analyzing trends in chemical concentrations in streams with a seasonal wave (seawave) and adjustment for streamflow (Q) and other ancillary variables

    USGS Publications Warehouse

    Ryberg, Karen R.; Vecchia, Aldo V.

    2013-01-01

    The seawaveQ R package fits a parametric regression model (seawaveQ) to pesticide concentration data from streamwater samples to assess variability and trends. The model incorporates the strong seasonality and high degree of censoring common in pesticide data and users can incorporate numerous ancillary variables, such as streamflow anomalies. The model is fitted to pesticide data using maximum likelihood methods for censored data and is robust in terms of pesticide, stream location, and degree of censoring of the concentration data. This R package standardizes this methodology for trend analysis, documents the code, and provides help and tutorial information, as well as providing additional utility functions for plotting pesticide and other chemical concentration data.

  16. Effective radium concentration in agricultural versus forest topsoils.

    PubMed

    Perrier, Frédéric; Girault, Frédéric; Bouquerel, Hélène; Bollinger, Laurent

    2016-08-01

    Effective radium-226 activity concentration (ECRa), the radon-222 source term, was measured in the laboratory with 724 topsoil samples collected over a ∼110 km(2) area located ∼20 km south of Paris, France. More than 2100 radon accumulation experiments were performed, with radon concentration measured using scintillation flasks, leading to relative uncertainties on ECRa varying from 10% for ECRa = 2 Bq⋅kg(-1) to less than 6% for ECRa > 5 Bq⋅kg(-1). Small-scale dispersion, studied at one location with 12 samples, and systematically at 100 locations with three topsoils separated by 1 m, was of the order of 7%, demonstrating that a single soil sample is reasonably representative. Agricultural topsoils (n = 540) had an average (arithmetic) ECRa of 8.09 ± 0.11 Bq⋅kg(-1), and a range from 2.80 ± 0.22 to 19.5 ± 1.1 Bq⋅kg(-1), while forest topsoils (n = 184), with an average of 3.21 ± 0.14 Bq⋅kg(-1) and a range from 0.45 ± 0.12 to 9.09 ± 0.55 Bq⋅kg(-1), showed a clear systematic reduction of ECRa when compared with the closest agricultural soil sample. Large-scale organization of ECRa was impressive for agricultural topsoils, with homogeneous domains of several kilometers size, characterized by smooth variations smaller than 10%. These patches emerged despite heavy human remodeling; they are controlled by the main geographical units, but do not necessarily coincide with them. Valleys were characterized by larger dispersion and less organization. This study illustrates how biosphere and anthroposphere modify the soil distribution inherited from geological processes, an important baseline needed for the study of contaminated sites. Furthermore, the observed depletion of forest topsoils suggests an atmospheric radon signature of deforestation. PMID:27176109

  17. Long-term trends in the concentrations of SF6, CHClF2, and COF2 in the lower stratosphere from analysis of high-resolution infrared solar occultation spectra

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Goldman, A.; Murcray, F. J.; Blatherwick, R. D.; Kosters, J. J.

    1990-01-01

    Long-term trends in the concentrations of SF6, CHClF2 in the lower stratosphere are derived using results from analyses of the 1980 and of several more recently obtained IR solar occultation spectra. Results show that the increase rates of SF6 and CHClF2 were about 7.4/yr and 9.4/yr, respectively, which correspond to cumulative increases by factors of about 1.7 and 2.0 in the concentrations of these gases over the 7.2 yr measurement period. The average increase rate for COF2 was 10.3/yr over the same time period. The present results are compared with previously reported observations and trends and with one-dimensional model calculations.

  18. Occurrence and trends in the concentrations of fecal-indicator bacteria and the relation to field water-quality parameters in the Allegheny, Monongahela, and Ohio Rivers and selected tributaries, Allegheny County, Pennsylvania, 2001–09

    USGS Publications Warehouse

    Fulton, John W.; Koerkle, Edward H.; McCoy, Jamie L.; Zarr, Linda F.

    2016-01-21

    A total of 1,742 water samples were collected at 52 main-stem and tributary sites. Quantifiable concentrations of Escherichia coli (E. coli) were reported in 1,667 samples, or 97.0 percent of 1,719 samples; concentrations in 853 samples (49.6 percent) exceeded the U.S. Environmental Protection Agency (EPA) recreational water-quality criterion of 235 colonies per 100 milliliters (col/100 mL). Quantifiable concentrations of fecal coliform (FC) bacteria were reported in 1,693 samples, or 98.8 percent of 1,713 samples; concentrations in 780 samples (45.5 percent) exceeded the Commonwealth of Pennsylvania water contact criterion of 400 col/100 mL. Quantifiable concentrations of enterococci bacteria were reported in 912 samples, or 87.5 percent of 1,042 samples; concentrations in 483 samples (46.4 percent) exceeded the EPA recreational water-quality criterion of 61 col/100 mL. The median percentage of samples in which bacteria concentrations exceeded recreational water-quality standards across all sites with five or more samples was 48 for E. coli, 43 for FC, and 75 for enterococci. E. coli, FC, and enterococci concentrations at main-stem sites had significant positive correlations with streamflow under all weather conditions, with rho values ranging from 0.203 to 0.598. Seasonal Kendall and logistic regression were evaluated to determine whether statistically significant trends were present during the period 2001–09. In general, Seasonal Kendall tests for trends in E. coli and FC bacteria were inconclusive. Results of logistic regression showed no significant trends in dry-weather exceedance of the standards; however, significant decreases in the likelihood that wet-weather E. coli and FC bacteria concentrations will exceed EPA recreational standards were found at the USGS streamgaging station Allegheny River at 9th Street Bridge. Nonparametric correlation analysis, including Spearman’s rho and the paired Prentice-Wilcoxon test, was used to screen for associations

  19. River chloride trends in snow-affected urban watersheds: increasing concentrations outpace urban growth rate and are common among all seasons.

    PubMed

    Corsi, Steven R; De Cicco, Laura A; Lutz, Michelle A; Hirsch, Robert M

    2015-03-01

    Chloride concentrations in northern U.S. included in this study have increased substantially over time with average concentrations approximately doubling from 1990 to 2011, outpacing the rate of urbanization in the northern U.S. Historical data were examined for 30 monitoring sites on 19 streams that had chloride concentration and flow records of 18 to 49 years. Chloride concentrations in most studied streams increased in all seasons (13 of 19 in all seasons; 16 of 19 during winter); maximum concentrations occurred during winter. Increasing concentrations during non-deicing periods suggest that chloride was stored in hydrologic reservoirs, such as the shallow groundwater system, during the winter and slowly released in baseflow throughout the year. Streamflow dependency was also observed with chloride concentrations increasing as streamflow decreased, a result of dilution during rainfall- and snowmelt-induced high-flow periods. The influence of chloride on aquatic life increased with time; 29% of sites studied exceeded the concentration for the USEPA chronic water quality criteria of 230 mg/L by an average of more than 100 individual days per year during 2006-2011. The rapid rate of chloride concentration increase in these streams is likely due to a combination of possible increased road salt application rates, increased baseline concentrations, and greater snowfall in the Midwestern U.S. during the latter portion of the study period. PMID:25514764

  20. River chloride trends in snow-affected urban watersheds: increasing concentrations outpace urban growth rate and are common among all seasons.

    PubMed

    Corsi, Steven R; De Cicco, Laura A; Lutz, Michelle A; Hirsch, Robert M

    2015-03-01

    Chloride concentrations in northern U.S. included in this study have increased substantially over time with average concentrations approximately doubling from 1990 to 2011, outpacing the rate of urbanization in the northern U.S. Historical data were examined for 30 monitoring sites on 19 streams that had chloride concentration and flow records of 18 to 49 years. Chloride concentrations in most studied streams increased in all seasons (13 of 19 in all seasons; 16 of 19 during winter); maximum concentrations occurred during winter. Increasing concentrations during non-deicing periods suggest that chloride was stored in hydrologic reservoirs, such as the shallow groundwater system, during the winter and slowly released in baseflow throughout the year. Streamflow dependency was also observed with chloride concentrations increasing as streamflow decreased, a result of dilution during rainfall- and snowmelt-induced high-flow periods. The influence of chloride on aquatic life increased with time; 29% of sites studied exceeded the concentration for the USEPA chronic water quality criteria of 230 mg/L by an average of more than 100 individual days per year during 2006-2011. The rapid rate of chloride concentration increase in these streams is likely due to a combination of possible increased road salt application rates, increased baseline concentrations, and greater snowfall in the Midwestern U.S. during the latter portion of the study period.

  1. River chloride trends in snow-affected urban watersheds: increasing concentrations outpace urban growth rate and are common among all seasons

    USGS Publications Warehouse

    Corsi, Steven R.; DeCicco, Laura A.; Lutz, Michelle A.; Hirsch, Robert M.

    2014-01-01

    Chloride concentrations in northern U.S. included in this study have increased substantially over time with average concentrations approximately doubling from 1990 to 2011, outpacing the rate of urbanization in the northern U.S. Historical data were examined for 30 monitoring sites on 19 streams that had chloride concentration and flow records of 18 to 49 years. Chloride concentrations in most studied streams increased in all seasons (13 of 19 in all seasons; 16 of 19 during winter); maximum concentrations occurred during winter. Increasing concentrations during non-deicing periods suggest that chloride was stored in hydrologic reservoirs, such as the shallow groundwater system, during the winter and slowly released in baseflow throughout the year. Streamflow dependency was also observed with chloride concentrations increasing as streamflow decreased, a result of dilution during rainfall- and snowmelt-induced high-flow periods. The influence of chloride on aquatic life increased with time; 29% of sites studied exceeded the concentration for the USEPA chronic water quality criteria of 230 mg/L by an average of more than 100 individual days per year during 2006–2011. The rapid rate of chloride concentration increase in these streams is likely due to a combination of possible increased road salt application rates, increased baseline concentrations, and greater snowfall in the Midwestern U.S. during the latter portion of the study period.

  2. Concentration trends for lead and calcium-normalized lead in fish fillets from the Big River, a mining-contaminated stream in southeastern Missouri USA

    USGS Publications Warehouse

    Schmitt, Christopher J.; McKee, Michael J.

    2016-01-01

    Lead (Pb) and calcium (Ca) concentrations were measured in fillet samples of longear sunfish (Lepomis megalotis) and redhorse suckers (Moxostoma spp.) collected in 2005–2012 from the Big River, which drains a historical mining area in southeastern Missouri and where a consumption advisory is in effect due to elevated Pb concentrations in fish. Lead tends to accumulated in Ca-rich tissues such as bone and scale. Concentrations of Pb in fish muscle are typically low, but can become elevated in fillets from Pb-contaminated sites depending in part on how much bone, scale, and skin is included in the sample. We used analysis-of-covariance to normalize Pb concentration to the geometric mean Ca concentration (415 ug/g wet weight, ww), which reduced variation between taxa, sites, and years, as was the number of samples that exceeded Missouri consumption advisory threshold (300 ng/g ww). Concentrations of Pb in 2005–2012 were lower than in the past, especially after Ca-normalization, but the consumption advisory is still warranted because concentrations were >300 ng/g ww in samples of both taxa from contaminated sites. For monitoring purposes, a simple linear regression model is proposed for estimating Ca-normalized Pb concentrations in fillets from Pb:Ca molar ratios as a way of reducing the effects of differing preparation methods on fillet Pb variation.

  3. Concentrations and time trends of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) in aquatic bird eggs from San Francisco Bay, CA 2000-2003

    USGS Publications Warehouse

    She, J.; Holden, A.; Adelsbach, T.L.; Tanner, M.; Schwarzbach, S.E.; Yee, J.L.; Hooper, K.

    2008-01-01

    Concentrations of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) were measured in 169 avian eggs. We analyzed randomly collected eggs of two species of piscivorous birds: Caspian tern (Sterna caspia) (n = 78) and Forster's tern (Sterna forsteri) (n = 76). We also analyzed fail-to-hatch eggs from two species protected under the Federal Endangered Species Act of 1973, that breed in the San Francisco Bay region: the piscivorous California Least tern (Sterna antillarum brownii) (n = 11) and the omnivorous California Clapper rail (Rallus longirostris obsoletus) (n = 4). San Francisco Bay eggs were collected annually for four years (2000-2003), and additional 20 eggs were collected and analyzed from Gray's Harbor, Washington in 2001. Geometric mean PBDE concentrations did not significantly differ in the three tern species, but concentrations in eggs from the fail to hatch California Clapper rail eggs were significantly lower than those found in the randomly collected tern eggs. Median concentrations of ???PBDEs in Caspian tern eggs for 2000-2003 were 2410, 4730, 3720 and 2880 ng/g lipid weight (lw), respectively, in Forster's terns 1820, 4380, 5460 and 3600 ng/g lw, respectively, and in California Least terns for 2001 and 2002 were 5060 and 5170 ng/g lw, respectively. In contrast, median ???PBDEs concentration in California Clapper rail eggs for 2001 was 379 ng/g lw. Five PBDEs were the major congeners found and decreased in the order BDE-47, -99, -100, -153, and -154. BDE-32, -28, -71, -66, -85, -183 were less prevalent, minor congeners, as was BDE-209, which was measured in a subset of samples. PBDE concentrations in bird eggs from San Francisco Bay were site related. There was no significant difference in PBDE concentrations in Caspian tern eggs from San Francisco Bay and Gray's Harbor, WA. Average PBDE concentrations in eggs did not significantly increase over the period 2000-2003. ?? 2008 Elsevier Ltd. All rights reserved.

  4. Evaluation of light-duty vehicle mobile source regulations on ozone concentration trends in 2018 and 2030 in the western and eastern United States.

    PubMed

    Collet, Susan; Minoura, Hiroaki; Kidokoro, Toru; Sonoda, Yukihiro; Kinugasa, Yukio; Karamchandani, Prakash

    2014-02-01

    To improve U.S. air quality, there are many regulations on-the-way (OTW) and on-the-books (OTB), including mobile source California Low Emission Vehicle third generation (LEV III) and federal Tier 3 standards. This study explores the effects of those regulations by using the U.S. Environmental Protection Agency's (EPA) Community Multiscale Air Quality (CMAQ) model for 8-hr ozone concentrations in the western and eastern United States in the years 2018 and 2030 during a month with typical high ozone concentrations, July. Alterations in pollutant emissions can be due to technological improvements, regulatory amendments, and changes in growth. In order to project emission rates for future years, the impacts of all of these factors were estimated. This study emphasizes the potential light-duty vehicle emission changes by year to predict ozone levels. The results of this study show that most areas have decreases in 8-hr ozone concentrations in the year 2030, although there are some areas with increased concentrations. Additionally, there are areas with 8-hr ozone concentrations greater than the current US. National Ambient Air Quality Standard level, which is 75 ppb.

  5. Spatial distribution and temporal trend in concentration of carbofuran, diazinon and chlorpyrifos ethyl residues in sediment and water in Lake Naivasha, Kenya.

    PubMed

    Otieno, Peter O; Schramm, Karl-Werner; Pfister, Gerd; Lalah, Joseph O; Ojwach, Stephen O; Virani, Munir

    2012-04-01

    Chlorpyrifos ethyl was found to be widely distributed in water and sediment in Lake Naivasha. Higher levels were reported in sediment (11.2-30.0 ng g(-1) dry weight (dw) in wet season than in dry season (4.7-17.4 ng g(-1) dw). The mean concentration of chlorpyrifos ethyl in water in wet season ranged between 8.8 and 26.6 μg L(-1) and decreased to between below detection limit to 14.0 μg L(-1) in dry season. On average, higher concentrations of chlorpyrifos ethyl were observed in sediment than water samples. Statistical analysis revealed a significant difference in concentration between the seasons, and a significant interaction between seasons and mean concentrations at p ≤ 0.05. However, levels of diazinon and carbofuran were below the detection limit in all the samples analyzed. Notably, levels of chlorpyrifos ethyl were higher than the maximum allowable limits (0.1 μg L(-1)) recommended by European Union for drinking water and general water quality criterion for protection of freshwater water organisms (0.083 μg L(-1)).

  6. Observed trends in ambient concentrations of C 2-C 8 hydrocarbons in the United Kingdom over the period from 1993 to 2004

    NASA Astrophysics Data System (ADS)

    Dollard, G. J.; Dumitrean, P.; Telling, S.; Dixon, J.; Derwent, R. G.

    Hourly measurements of up to 26 C 2-C 8 hydrocarbons have been made at eight urban background sites, three urban-industrial sites, a kerbside and a rural site in the UK from 1993 onwards up until the end of December 2004. Average annual mean benzene and 1,3-butadiene concentrations at urban background locations have declined at about -20% per year and the observed declines have exactly mimicked the inferred declines in benzene and 1,3-butadiene emissions over the same period. Ninety-day rolling mean concentrations of ethylene, propylene, n- and i-butane, n- and i-pentane, isoprene and propane at urban and rural sites have also declined steadily by between -10% and -30% per year. Rolling mean concentrations of acetylene, 2- and 3-methylpentane, n-hexane, n-heptane, cis- and trans-but-2-ene, cis- and trans-pent-2-ene, toluene, ethylbenzene and o-, m- and p-xylene at a roadside location in London have all declined at between -14% and -21% per year. These declines demonstrate that motor vehicle exhaust catalysts and evaporative canisters have effectively and efficiently controlled vehicular emissions of hydrocarbons in the UK. Urban ethane concentrations arising largely from natural gas leakage have remained largely unchanged over this same period.

  7. Metals and metalloids in fruits of tomatoes (Solanum lycopersicum) and their cultivation soils in the Basque Country: concentrations and accumulation trends.

    PubMed

    Rodriguez-Iruretagoiena, Azibar; Trebolazabala, Josu; Martinez-Arkarazo, Irantzu; de Diego, Alberto; Madariaga, Juan Manuel

    2015-04-15

    The concentrations of several elements (Al, Fe, As, Cu, Cd, Co, Cr, Mn, Ni, Pb, Sn, V, and Zn) were measured in soils and the edible part of different vegetables (tomatoes (Solanum lycopersicum "Raf") peppers (Capsicum annuum), chards (Betavulgaris var. cicla), artichokes (Cynarascholymus)) and fruits (Raspberries (Rubusidaeus)) from 13 orchards in the Basque Country affected by different pollution sources. Multivariate analysis of data was used to look for possible correlations between metals in soil and metals in the edible part of the plant. Only manganese showed a correlation significantly different from zero. The metal concentrations found in the edible part were always below the upper limits recommended by the European legislation in force. The Bioaccumulation Index was used to investigate how efficient the plant is to uptake an element from the cultivation soil and to preserve its edible part from the element. PMID:25466128

  8. Metals and metalloids in fruits of tomatoes (Solanum lycopersicum) and their cultivation soils in the Basque Country: concentrations and accumulation trends.

    PubMed

    Rodriguez-Iruretagoiena, Azibar; Trebolazabala, Josu; Martinez-Arkarazo, Irantzu; de Diego, Alberto; Madariaga, Juan Manuel

    2015-04-15

    The concentrations of several elements (Al, Fe, As, Cu, Cd, Co, Cr, Mn, Ni, Pb, Sn, V, and Zn) were measured in soils and the edible part of different vegetables (tomatoes (Solanum lycopersicum "Raf") peppers (Capsicum annuum), chards (Betavulgaris var. cicla), artichokes (Cynarascholymus)) and fruits (Raspberries (Rubusidaeus)) from 13 orchards in the Basque Country affected by different pollution sources. Multivariate analysis of data was used to look for possible correlations between metals in soil and metals in the edible part of the plant. Only manganese showed a correlation significantly different from zero. The metal concentrations found in the edible part were always below the upper limits recommended by the European legislation in force. The Bioaccumulation Index was used to investigate how efficient the plant is to uptake an element from the cultivation soil and to preserve its edible part from the element.

  9. Tracing historical trends of Hg in the Mississippi River using Hg concentrations and Hg isotopic compositions in a lake sediment core, Lake Whittington, Mississippi, USA

    USGS Publications Warehouse

    Gray, John E.; Van Metre, Peter C.; Pribil, Michael J.; Horowitz, Arthur J.

    2015-01-01

    Concentrations and isotopic compositions of mercury (Hg) in a sediment core collected from Lake Whittington, an oxbow lake on the Lower Mississippi River, were used to evaluate historical sources of Hg in the Mississippi River basin. Sediment Hg concentrations in the Lake Whittington core have a large 10-15 y peak centered on the 1960s, with a maximum enrichment factor relative to Hg in the core of 4.8 in 1966. The Hg concentration profile indicates a different Hg source history than seen in most historical reconstructions of Hg loading. The timing of the peak is consistent with large releases of Hg from Oak Ridge National Laboratory (ORNL), primarily in the late 1950s and 1960s. Mercury was used in a lithiumisotope separation process by ORNL and an estimated 128Mg (megagrams) of Hgwas discharged to a local stream that flows into the Tennessee River and, eventually, the Mississippi River. Mass balance analyses of Hg concentrations and isotopic compositions in the Lake Whittington core fit a binary mixing model with a Hg-rich upstream source contributing about 70% of the Hg to Lake Whittington at the height of the Hg peak in 1966. This upstream Hg source is isotopically similar to Hg isotope compositions of stream sediment collected downstream near ORNL. It is estimated that about one-half of the Hg released from the ORNL potentially reached the LowerMississippi River basin in the 1960s, suggesting considerable downstream transport of Hg. It is also possible that upstream urban and industrial sources contributed some proportion of Hg to Lake Whittington in the 1960s and 1970s.

  10. Application of a Weighted Regression Model for Reporting Nutrient and Sediment Concentrations, Fluxes, and Trends in Concentration and Flux for the Chesapeake Bay Nontidal Water-Quality Monitoring Network, Results Through Water Year 2012

    USGS Publications Warehouse

    Chanat, Jeffrey G.; Moyer, Douglas L.; Blomquist, Joel D.; Hyer, Kenneth E.; Langland, Michael J.

    2016-01-13

    WRTDS also was used to explore the sensitivity of flux and trend estimates to three data-quality issues common in many large-scale monitoring networks and evident in some of the CBNTN records. The potential effects of inconsistency in annual sampling effort and inconsistency in storm sampling effort were explored by way of a subsampling experiment using eight of the most densely sampled long-term (1985–2012) stations in the CBNTN as baseline datasets. From each dataset, a set of 10 “design guideline” subsamples was selected, consisting of 12 monthly samples and 8 targeted storm samples per year. The selection was conducted in a manner that preserved the overall intensity of storm sampling in the baseline data. These 10 subsamples were further manipulated to create “heterogeneous” subsamples by removing storm samples prior to 2003. The maximum relative difference between flow-normalized flux estimated in a single year from any of the 10 design guideline subsamples and values estimated in the corresponding year from baseline data was smallest for dissolved inorganic nitrogen (median of 8 stations = 6 percent of baseline estimate), but more appreciable for total phosphorus and sediment (medians of 22 and 32 percent, respectively). The maximum relative difference between flow-normalized flux estimated from from the 10 heterogeneous subsamples and values estimated in the

  11. LABORATORY, FIELD AND MODELING STUDIES OF RADON-222 AS A NATURAL TRACER FOR MONITORING NAPL CONTAMINATION. (R825689C058)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  12. Novel determination of radon-222 velocity in deep subsurface rocks, and the feasibility to using radon as an earthquake precursor

    NASA Astrophysics Data System (ADS)

    Zafrir, Hovav; Benhorin, Yochy; Malik, Uri; Chemo, Chaim

    2016-04-01

    An enhanced radon monitoring system was designed in order to study shallow versus deep subsurface processes affecting the appearance of radon anomalies. The method is based on the assumption that the climatic influence is limited since its energy decreases with the decrease in thickness of the geological cover whereby its effect is reduced to a negligible value at depth. Hence, lowering gamma and alpha detectors into deep boreholes and monitoring their temporal variations relative to a reference couple at shallow depths of 10-40 m eliminates the ambient thermal and pressure-induced contribution from the total radon time series. It allows highlighting the residual portion of the radon signals that might be associated with the geodynamic processes. The primary technological key is the higher sensitivity of the gamma detectors - in comparison to the solid-state alpha detectors, which are also suitable for threading into narrow boreholes in parallel to the narrow gamma detector (Zafrir et al., 2013*). The unique achievements of the novel system that was installed at the Sde Eliezer site close to the Hula Valley western border fault (HWBF) in northern Israel are: a) Determination, for the first time, of the radon movement velocity within rock layers at depths of several tens of meters, namely, 25 m per hour on average; b) Distinguishing between the diurnal periodical effect of the ambient temperature and the semi-diurnal effect of the ambient pressure on the radon temporal spectrum; c) Identification of a radon random pre-seismic anomaly preceding the Nuweiba, M 5.5 earthquake of 27 June 2015 that occurred within Dead Sea Fault Zone. * Zafrir, H., Barbosa, S.M. and Malik, U., 2013. Differentiation between the effect of temperature and pressure on radon within the subsurface geological media, Radiat. Meas., 49, 39-56. doi:10.1016/j.radmeas.2012.11.019.

  13. Push-pull partitioning tracer tests using radon-222 to quantify non-aqueous phase liquid contamination.

    PubMed

    Davis, B M; Istok, J D; Semprini, L

    2002-09-01

    Naturally occurring radon in groundwater can be used as an in situ partitioning tracer for locating and quantifying non-aqueous phase liquid (NAPL) contamination in the subsurface. When combined with the single-well, push-pull test, this methodology has the potential to provide a low-cost alternative to inter-well partitioning tracer tests. During a push-pull test, a known volume of test solution (radon-free water containing a conservative tracer) is first injected ("pushed") into a well; flow is then reversed and the test solution/groundwater mixture is extracted ("pulled") from the same well. In the presence of NAPL radon transport is retarded relative to the conservative tracer. Assuming linear equilibrium partitioning, retardation factors for radon can be used to estimate NAPL saturations. The utility of this methodology was evaluated in laboratory and field settings. Laboratory push-pull tests were conducted in both non-contaminated and trichloroethene NAPL (TCE)-contaminated sediment. The methodology was then applied in wells located in non-contaminated and light non-aqueous phase liquid (LNAPL)-contaminated portions of an aquifer at a former petroleum refinery. The method of temporal moments and an approximate analytical solution to the governing transport equations were used to interpret breakthrough curves and estimate radon retardation factors; estimated retardation factors were then used to calculate TCE saturations. Numerical simulations were used to further investigate the behavior of the breakthrough curves. The laboratory and field push-pull tests demonstrated that radon retardation does occur in the presence of TCE and LNAPL and that radon retardation can be used to calculate TCE saturations. Laboratory injection-phase test results in TCE-contaminated sediment yielded radon retardation factors ranging from 1.1 to 1.5, resulting in calculated TCE saturations ranging from 0.2 to 0.9%. Laboratory extraction-phase test results in the same sediment yielded a radon retardation factor of 5.0, with a calculated TCE saturation of 6.5%. Numerical simulation breakthrough curves provided reasonably good matches to the approximate analytical solution breakthrough curves. However, non-equilibrium radon partitioning and heterogeneous TCE distributions may affect the retardation factors and TCE saturation estimates.

  14. Using radon-222 to study coastal groundwater/surface-water interaction in the Crau coastal aquifer (southeastern France)

    NASA Astrophysics Data System (ADS)

    Mayer, Adriano; Nguyen, Bach Thao; Banton, Olivier

    2016-05-01

    Radon has been used to determine groundwater velocity and groundwater discharge into wetlands at the southern downstream boundary of the Crau aquifer, southeastern France. This aquifer constitutes an important high-quality freshwater resource exploited for agriculture, industry and human consumption. An increase in salinity occurs close to the sea, highlighting the need to investigate the water balance and groundwater behavior. Darcy velocity was estimated using radon activities in well waters according to the Hamada "single-well method" (involving comparison with radon in groundwater in the aquifer itself). Measurements done at three depths (7, 15 and 21 m) provided velocity ranging from a few mm/day to more than 20 cm/day, with highest velocities observed at the 15-m depth. Resulting hydraulic conductivities agree with the known geology. Waters showing high radon activity and high salinity were found near the presumed shoreline at 3,000 yearsuc( BP), highlighting the presence of ancient saltwater. Radon activity has also been measured in canals, rivers and ponds, to trace groundwater discharges and evaluate water balance. A model of the radon spatial evolution explains the observed radon activities. Groundwater discharge to surface water is low in pond waters (4 % of total inputs) but significant in canals (55 l/m2/day).

  15. Using radon-222 as indicator for the evaluation of the efficiency of groundwater remediation by in situ air sparging.

    PubMed

    Schubert, Michael; Schmidt, Axel; Müller, Kai; Weiss, Holger

    2011-02-01

    A common approach for remediation of groundwater contamination with volatile organic compounds (VOCs) is contaminant stripping by means of in situ air sparging (IAS). For VOC stripping, pressurized air is injected into the contaminated groundwater volume, followed by the extraction of the contaminant-loaded exhaust gas from the vadose soil zone and its immediate on-site treatment. Progress assessment of such remediation measure necessitates information (i) on the spatial range of the IAS influence and (ii) on temporal variations of the IAS efficiency. In the present study it was shown that the naturally occurring noble gas radon can be used as suitable environmental tracer for achieving the related spatial and temporal information. Due to the distinct water/air partitioning behaviour of radon and due to its straightforward on-site detectability, the radon distribution pattern in the groundwater can be used as appropriate measure for assessing the progression of an IAS measure as a function of space and time. The presented paper discusses both the theoretical background of the approach and the results of an IAS treatment accomplished at a VOC contaminated site lasting six months, during which radon was applied as efficiency indicator.

  16. Trends and variability in blood lead concentrations among US adults aged 20-64 years and senior citizens aged ≥65 years.

    PubMed

    Jain, Ram B

    2016-07-01

    Using data from National Health and Nutrition Examination Survey for the period 2003-2012, the objective of this study was to evaluate trends in blood lead levels (BLL) among adults aged 20-64 years (adults) and seniors aged ≥65 years (seniors). In addition, the contribution of other factors like gender, race/ethnicity, smoking, and exposure to secondhand smoke at home in explaining variability in BLL was also evaluated by fitting regression models with log10 transformed values of BLL as dependent variables. BLL decreased over 2003-2012 (p < 0.01). Irrespective of gender, race/ethnicity, and smoking status, seniors were found to have higher BLL than adults. Based on the magnitude of differences between the 5th and 95th percentiles, variability in the levels of blood lead was found to be substantially higher among seniors than among adults. Males had statistically significantly higher adjusted BLL than females (2.32 vs. 1.76 μg/dL for seniors, p < 0.01 and 1.66 vs. 1.13 μg/dL for adults, p < 0.01). Non-Hispanic whites had statistically significantly lower adjusted BLL than non-Hispanic blacks (1.99 vs. 2.42 μg/dL for seniors, p < 0.01 and 1.22 vs. 1.42 μg/dL for adults, p < 0.01). When compared with non-smokers, smokers had statistically significantly higher BLL (2.19 vs. 1.86 μg/dL for seniors, p < 0.01 and 1.54 vs. 1.22 μg/dL for adults, p < 0.01). Non-obese had statistically significantly higher BLL than obese individuals (2.11 vs. 1.93 μg/dL for seniors, p < 0.01 and 1.48 vs. 1.27 μg/dL for adults, p < 0.01). Exposure to secondhand smoke at home (SHS) was associated with statistically significantly higher BLL than when there was no exposure to SHS (β = 0.0683, p = 0.03 for seniors; β = 0.034, p = 0.034, p < 0.01 for adults). PMID:27044289

  17. Sulphate concentration in cave dripwater and speleothems: long-term trends and overview of its significance as proxy for environmental processes and climate changes

    NASA Astrophysics Data System (ADS)

    Borsato, Andrea; Frisia, Silvia; Wynn, Peter M.; Fairchild, Ian J.; Miorandi, Renza

    2015-11-01

    Sulphate concentrations in speleothems identify major volcanic eruptions, provide useful information on soil and aquifer dynamics and, in similar fashion to the 14C bomb peak, its Anthropocene peak can be used to date recent cave formations. However, the transmission of S from the atmosphere to cave dripwater and its incorporation in speleothems is subjected to biogeochemical cycling and accurate studies of each cave site are needed in order to assess how the S atmospheric signal is modified and eventually encoded in speleothems. This study investigates the role of biogeochemical cycling and aquifer hydrology by utilising published and new dripwater and speleothem data from Grotta di Ernesto (ER) in northern Italy. Here we provide the first long-term record of sulphate concentration in cave dripwater based on over 20 years of measurements. Fast drip site st-ER1 is characterised by a continuous decrease in SO4 concentration from a high of 7.5 ± 0.8 mg/l in 1993-1994 to a low of 2.2 ± 0.2 mg/l in 2013-2014, and replicates with a delay of ˜15 years the decline in the atmospheric SO2 emissions. The S-series of slow flow ER78 site is further delayed by ˜4.5 years in relation to the S retention in the aquifer matrix. The dripwater data are used to extend the previously published S record (1810-1998 AD) of stalagmite ER78 and reconstruct the anthropogenic S-peak: this displays a delay of ˜20 years with respect to the atmospheric S emission peak due to biogeochemical cycling and aquifer storage. However, sulphur recycling above the cave did not operate with the same degree of efficiency through time, which resulted in a variable time delay between S deposition and incorporation into the stalagmite. In the pre-Anthropocene era, and in particular during the cold Little Ice Age, biogeochemical cycling was far less efficient than today, and the fast transmission of the atmospheric signal allowed capture of S released during major volcanic eruptions by stalagmites.

  18. Long-Term Trends in the Concentrations of SF6, CHClF2, and COF2 in the Lower Stratosphere from Analysis of High-Resolution Infrared Solar Occultation Spectra

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Goldman, A.; Murcray, F. J.; Blatherwick, R. D.; Kosters, J. J.; Murcray, D. G.; Sze, N. D.; Massie, S. T.

    1990-01-01

    Long-term trends in the concentrations of SF6, CHClF2 (CFC-22), and COF2 in the lower stratosphere have been derived from analysis of ca. 1980 and more recent infrared solar occultation spectra recorded near 32 deg N latitude at approx. 0.02/ cm resolution. Consistent sets of line parameters and spectral calibration methods have been used in the retrievals to minimize systematic error effects. Quoted error limits are 1 sigma estimated precisions. The SF6 and CHClF2 results are based on spectra recorded by balloon-borne interferometers in March 1981 and June 1988 and a comparison of these results with the Atmospheric Trace Molecule Spectroscopy (ATMOS) Experiment/Spacelab 3 measurements obtained in May 1985 near 30 deg N latitude. In the 13-18 km altitude range the mean measured SF6 mixing ratio in parts per trillion by volume (pptv) increased from 1.17 +/- 0.21 in March 1981 to 2.02 +/- 0.20 pptv in June 1988, and the CHClF2 mixing ratio below 15 km altitude increased from 51 +/- 8 pptv in March 1981 to 102 +/- 10 pptv in June 1988. The CHClF2 retrievals used new empirical CHClF2 line parameters derived from 0.03/cm resolution laboratory spectra recorded at six temperatures between 203 and 293 K; the derived mixing ratios are approx. 30% higher than obtained with earlier sets of line parameters, thereby removing a large discrepancy noted previously between IR and in situ measurements of CHClF2. Assuming an exponential growth model for fitting the trends, SF6 and CHClF2 mean increase rates of 7.4% +/- 1.9% and 9.4% +/- 1.3% /year, are obtained, respectively, which correspond to cumulative increases by factors of approx. 1.7 and -2.0 in the concentrations of these gases over the 7.2-year measurement period. Analysis of spectra recorded in October 1979 and April 1989 yields COF2 volume mixing ratios that are respectively 0.44 +/- 0.17 and 1.21 +/- 0.24 times the ATMOS/Spacelab 3 values, from which an average COF2 increase rate of 10.3 +/- 1.8%/ year over this time

  19. Instructional Time Trends. Education Trends

    ERIC Educational Resources Information Center

    Woods, Julie Rowland

    2015-01-01

    For more than 30 years, Education Commission of the States has tracked instructional time and frequently receives requests for information about policies and trends. In this Education Trends report, Education Commission of the States addresses some of the more frequent questions, including the impact of instructional time on achievement, variation…

  20. First analysis of 10-year trends in national factor concentrates usage in haemophilia: data from CHARMS, the Canadian Hemophilia Assessment and Resource Management System.

    PubMed

    Traore, A N; Chan, A K C; Webert, K E; Heddle, N; Ritchie, B; St-Louis, J; Teitel, J; Lillicrap, D; Iorio, A; Walker, I

    2014-07-01

    The Canadian Hemophilia Assessment and Resource Management System (CHARMS) tracks factor concentrates (FC) from the sole suppliers, Canadian Blood Services (CBS) and Hema-Quebec (HQ), to hospitals and to patients' homes. Patients FC infusion data are entered into CHARMS at Canadian Hemophilia Treatment Centres (HTCs) then exported to the national database (CentrePoint). From 2000 to 2009, 2260 registered haemophilia A or B patients received FVIII (1,009,097,765 IU) and FIX (272,406,859 IU). Over 91% of FVIII and over 84% of FIX was infused at home. Utilization of FVIII progressively increased; this was accounted for by an increase in the number of patients treated (r = 0.97; P < 0.001), there being a linear relationship between the increase in utilization and the increase in number of patients treated (P < 0.001). There was also a correlation with the annual amount used per patient (r = 0.95; P < 0.001). Utilization of FIX did not increase over time. The highest proportional utilization of both FVIII and FIX was for prophylaxis, and this proportion progressively increased being, in year 10 (2009), 77% and 66% for FVIII and FIX respectively. The proportion used for bleeding remained steady; in year 10 that proportion was 14% for FVIII and 26% for FIX, the use per patient for bleeding decreasing. The HTC-based CHARMS tracking system is essential, in Canada, for analysing indications for infusion, for predicting utilization and planning for future needs.

  1. Semi-volatile organic compounds (SVOCs) in ambient air and rainwater in a tropical environment: concentrations and temporal and seasonal trends.

    PubMed

    He, Jun; Balasubramanian, Rajasekhar

    2010-02-01

    The levels of a range of SVOCs (PAHs, OCPs, and PCBs) in atmospheric particulate and gaseous phases and rainwater samples were studied in Singapore from June 2007 to May 2008. Yearly average concentrations of PAHs, OCPs and PCBs in air (particle+gas) were 136.5 ng m(-3), 695.8 pg m(-3) and 27 pg m(-3), respectively while those of PAHs and OCPs in rainwater (particulate+dissolved) were 1218.1 and 114.2 ng L(-1), respectively. The lower molecular weight (LMW) PAHs were more abundant than those higher molecular weight (HMW) PAHs in rainwater. Among OCPs, HCHs were found in rainwater in relatively larger amounts than DDTs. Similar distributions patterns were also found in air samples. Statistical correlation analysis indicated that the atmospheric occurrence of SVOCs had positive correlation with ambient temperature except for particulate PAHs and negative correlations with relative humidity and wind speed; incoming solar radiation (SR) was negatively associated with PAHs, but there was almost no correlation between SR and the occurrence of OCPs and PCBs. ANOVA analysis revealed that the temporal variations were statistically significant for PAHs and PCBs in air samples and for OCPs in rainwater. In addition, local traffic emissions, trans-boundary transport of pesticides from regional sources and Aroclors 1248 and 1254 were identified as probable sources for PAHs, OCPs and PCBs in the atmosphere, respectively, based on molecular diagnostic ratios and principal component analysis (PCA) together with the assistance of air mass backward trajectories. PMID:19922976

  2. Heavy metal concentrations in great blue heron fecal castings in Washington State: A technique for monitoring regional and global trends in environmental contaminants

    SciTech Connect

    Fitzner, R.E.; Gray, G.H.; Hinds, W.T.

    1995-09-01

    Growing concern over the world`s environment necessitates development of methods to monitor environmental changes over time. Various proposals involving {open_quotes}literally{close_quotes} thousands of useful ecological indicators have been published over the past two or three decades, including the theoretical foundations for the use of indicators in ecosystem-based monitoring. Sampling of animals often requires a choice between killing individuals in the field to allow measurement, or using a non-destructive sampling technique. Sampling of feathers to determine metal concentrations in tropical Pacific Rim birds, including herons, was reported by Burger, Burger and Gochfeld, and Burger et al. While collection of feathers did not harm the birds, the feathers still had to be plucked from the birds. We report a method that does not involve disturbing the birds. Great blue herons (Ardea herodius) feed at the top of a diverse but reasonably well understood food web. The birds are colonial during their reproductive season, and gather into identifiable, replicable, and annually repeated groups, using the same nests (usually in trees) for years at a time. Herons maintain nests free of regurgitated prey parts and nestling fecal materials by discarding detritus and fecal sacs over the nest edge. This behavior produces a {open_quotes}rain{close_quotes} of fecal matter including identifiable discarded or undigested items (e.g., bones) that reflect the food on which herons prey. Collecting this material provides a quantifiable estimate of contaminants in the food web and makes the heron a prime sampling target. We discuss here the results of a two-year study designed to determine the relationship between heavy metal residues in heron fecal castings and those in heron tissues from the same colonies. We also evaluated whether analysis of heron excrement was a reliable indication of heavy metals in the environment. 12 refs., 2 tabs.

  3. Nationwide Trends

    MedlinePlus

    ... Charts Emerging Trends and Alerts Alcohol Club Drugs Cocaine Hallucinogens Heroin Inhalants Marijuana MDMA (Ecstasy/Molly) Methamphetamine ... includes ecstasy and LSD) in the past month. Cocaine use has gone down in the last few ...

  4. Global, regional, and national trends in haemoglobin concentration and prevalence of total and severe anaemia in children and pregnant and non-pregnant women for 1995–2011: a systematic analysis of population-representative data

    PubMed Central

    Stevens, Gretchen A; Finucane, Mariel M; De-Regil, Luz Maria; Paciorek, Christopher J; Flaxman, Seth R; Branca, Francesco; Peña-Rosas, Juan Pablo; Bhutta, Zulfiqar A; Ezzati, Majid

    2013-01-01

    Summary Background Low haemoglobin concentrations and anaemia are important risk factors for the health and development of women and children. We estimated trends in the distributions of haemoglobin concentration and in the prevalence of anaemia and severe anaemia in young children and pregnant and non-pregnant women between 1995 and 2011. Methods We obtained data about haemoglobin and anaemia for children aged 6–59 months and women of childbearing age (15–49 years) from 257 population-representative data sources from 107 countries worldwide. We used health, nutrition, and household surveys; summary statistics from WHO's Vitamin and Mineral Nutrition Information System; and summary statistics reported by other national and international agencies. We used a Bayesian hierarchical mixture model to estimate haemoglobin distributions and systematically addressed missing data, non-linear time trends, and representativeness of data sources. We quantified the uncertainty of our estimates. Findings Global mean haemoglobin improved slightly between 1995 and 2011, from 125 g/L (95% credibility interval 123–126) to 126 g/L (124–128) in non-pregnant women, from 112 g/L (111–113) to 114 g/L (112–116) in pregnant women, and from 109 g/L (107–111) to 111 g/L (110–113) in children. Anaemia prevalence decreased from 33% (29–37) to 29% (24–35) in non-pregnant women, from 43% (39–47) to 38% (34–43) in pregnant women, and from 47% (43–51) to 43% (38–47) in children. These prevalences translated to 496 million (409–595 million) non-pregnant women, 32 million (28–36 million) pregnant women, and 273 million (242–304 million) children with anaemia in 2011. In 2011, concentrations of mean haemoglobin were lowest and anaemia prevalence was highest in south Asia and central and west Africa. Interpretation Children's and women's haemoglobin statuses improved in some regions where concentrations had been low in the 1990s, leading to a modest global increase in

  5. Trends in source gases

    NASA Technical Reports Server (NTRS)

    Ehhalt, D. H.; Fraser, P. J.; Albritton, D.; Cicerone, R. J.; Khalil, M. A. K.; Legrand, M.; Makide, Y.; Rowland, F. S.; Steele, L. P.; Zander, R.

    1989-01-01

    Source gases are defined as those gases that, by their breakdown, introduce into the stratosphere halogen, hydrogen, and nitrogen compounds that are important in stratospheric ozone destruction. Given here is an update of the existing concentration time series for chlorocarbons, nitrous oxide, and methane. Also reviewed is information on halogen containing species and the use of these data for establishing trends. Also reviewed is evidence on trends in trace gases that influence tropospheric chemistry and thus the tropospheric lifetimes of source gases, such as carbon dioxide, carbon monoxide, or nitrogen oxides. Much of the information is given in tabular form.

  6. DICARBOXYLIC ACID CONCENTRATION TRENDS AND SAMPLING ARTIFACTS

    EPA Science Inventory

    Dicarboxylic acids associated with airborne particulate matter were measured during a summer period in Philadelphia that included multiple air pollution episodes. Samples were collected for two ten hour periods each day using a high volume sampler with two quartz fiber filters in...

  7. Environmental Trends.

    ERIC Educational Resources Information Center

    Council on Environmental Quality, Washington, DC.

    This document consists of data which highlight trends in all sectors relevant to environmental policy. These data are presented in the form of charts and maps contained in 13 sections under the following headings: people and the land; critical areas (wetlands, wild areas, parks, historic places, and risk zones); human settlements; transportation;…

  8. Radium distribution and indoor radon in the Pacific Northwest

    USGS Publications Warehouse

    Duval, J.S.; Otton, J.K.

    1990-01-01

    Aerial gamma-ray data were compiled to produce a map showing the distribution of radium (226Ra) in near-surface materials in the Pacific Northwest, (Washington, Oregon, and Idaho, and parts of Montana, Wyoming, California, Nevada, and Utah). A comparison of measurements of indoor concentration levels of radon (222Rn) in homes with the apparent surface concentration of radium shows that aerial gamma-ray data provide a first order estimate of the relative amounts of indoor radon for township-sized areas where soils have low to moderate permeability. Townships with average indoor radon levels above the general trend of the data are almost all characterized by soils that have higher intrinsic permeabilities. -Authors

  9. Differences of near-ground atmospheric Rn-222 concentration between urban and rural area with reference to microclimate diversity

    NASA Astrophysics Data System (ADS)

    Podstawczyńska, Agnieszka

    2016-02-01

    A unique 4-year dataset of hourly near-surface meteorological and atmospheric Radon-222 measurements made simultaneously at adjacent rural and urban sites in central Poland are presented and discussed. The annual, seasonal and diurnal variations of Rn-222 concentration were analysed. The magnitude of the urban heat island effect (UHI: difference in 2 m air temperature between the urban and rural regions) was found to be reasonably well correlated with traditional atmospheric stability indicators (i.e. wind speed and near-surface temperature gradient). To better quantify the influence of the UHI on the strength/depth of nocturnal mixing, the rural radon observations were used to classify the nocturnal mixing state regionally on a nightly basis, enabling a comparison between the rural and urban observations over four stability categories ranging from near-neutral to stable. Averaged over the entire dataset, near-neutral nocturnal conditions were characterised by 2 m wind speeds, U2m, of ˜1.3 m s-1 and 2-0.2 m temperature gradients, ΔT, of ˜0.5 °C in the rural region, compared to U2m = 1.15 m s-1 and ΔT = -0.24 °C in the urban region. By comparison, under regionally stable conditions U2m = 0.6 m s-1 and ΔT = 1.5-2.0 °C in the rural region and U2m = 0.8 m s-1 and ΔT = -0.25 °C in the urban region. Between near-neutral to stable conditions, the nocturnal UHI varied from ˜0.8 to 2.4 °C. The higher wind speeds under regionally stable conditions in the urban centre compared to the rural region (25 km distant) indicate that the slightly unstable conditions and UHI = 2.4 °C are sufficient to sustain a meso-scale circulation cell. The effect that the nocturnal urban heating has locally on the atmosphere's ability to dilute primary pollutants at night is indicated by the contrasting diurnal amplitude of radon concentration at each site under regionally stable conditions: ˜9 Bq m-3 in the rural region and ˜2 Bq m-3 in the urban region.

  10. Nitrate Trends in Minnesota Rivers

    USGS Publications Warehouse

    Wall, Dave; Christopherson, Dave; Lorenz, Dave; Martin, Gary

    2013-01-01

    The objective of this study was to assess long-term trends (30 to 35 years) of flow-adjusted concentrations of nitrite+nitrate-N (hereinafter referred to as nitrate) in a way that would allow us to discern changing trends. Recognizing that these trends are commonly different from one river to another river and from one part of the state to another, our objective was to examine as many river monitoring sites across the state as possible for which sufficient long term streamflow and concentration data were available.

  11. Global trends

    NASA Technical Reports Server (NTRS)

    Megie, G.; Chanin, M.-L.; Ehhalt, D.; Fraser, P.; Frederick, J. F.; Gille, J. C.; Mccormick, M. P.; Schoebert, M.; Bishop, L.; Bojkov, R. D.

    1990-01-01

    Measuring trends in ozone, and most other geophysical variables, requires that a small systematic change with time be determined from signals that have large periodic and aperiodic variations. Their time scales range from the day-to-day changes due to atmospheric motions through seasonal and annual variations to 11 year cycles resulting from changes in the sun UV output. Because of the magnitude of all of these variations is not well known and highly variable, it is necessary to measure over more than one period of the variations to remove their effects. This means that at least 2 or more times the 11 year sunspot cycle. Thus, the first requirement is for a long term data record. The second related requirement is that the record be consistent. A third requirement is for reasonable global sampling, to ensure that the effects are representative of the entire Earth. The various observational methods relevant to trend detection are reviewed to characterize their quality and time and space coverage. Available data are then examined for long term trends or recent changes in ozone total content and vertical distribution, as well as related parameters such as stratospheric temperature, source gases and aerosols.

  12. Effects of Radon Inhalation on Some Biophysical Properties of Blood in Rats

    NASA Astrophysics Data System (ADS)

    Essa, M. F.; Shahin, Fayez M.; Ahmed, Ashour M.; Abdel-Salam, Omar

    2013-03-01

    The major source of human exposure to natural radiation arises from the inhalation of radon (222Rn) gas. Exposure to high concentrations of radon 222Rn and its daughters for long period leads to pathological effects like lung cancer, leukaemia, skin cancer and kidney diseases. The present study was performed on rats to investigate the effect of radon exposure on the absorption spectra of hemoglobin. Measurements have been performed in a radon chamber where rats were exposed to radon for 1, 5 or 7 weeks. The inhalation of radon resulted in decrease in intensity of the absorption bands characterizing the hemoglobin molecular structure with increased radon doses.

  13. Concentration, flux, and the analysis of trends of total and dissolved phosphorus, total nitrogen, and chloride in 18 tributaries to Lake Champlain, Vermont and New York, 1990–2011

    USGS Publications Warehouse

    Medalie, Laura

    2013-01-01

    Annual concentration, flux, and yield for total phosphorus, dissolved phosphorus, total nitrogen, and chloride for 18 tributaries to Lake Champlain were estimated for 1990 through 2011 using a weighted regression method based on time, tributary streamflows (discharges), and seasonal factors. The weighted regression method generated two series of daily estimates of flux and concentration during the period of record: one based on observed discharges and a second based on a flow-normalization procedure that removes random variation due to year-to-year climate-driven effects. The flownormalized estimate for a given date is similar to an average estimate of concentration or flux that would be made if all of the observed discharges for that date were equally likely to have occurred. The flux bias statistic showed that 68 of the 72 flux regression models were minimally biased. Temporal trends in the concentrations and fluxes were determined by calculating percent changes in flow-normalized annual fluxes for the full period of analysis (1990 through 2010) and for the decades 1990–2000 and 2000–2010. Basinwide, flow-normalized total phosphorus flux decreased by 42 metric tons per year (t/yr) between 1990 and 2010. This net result reflects a basinwide decrease in flux of 21 metric tons (t) between 1990 and 2000, followed by a decrease of 20 t between 2000 and 2010; both results were largely influenced by flux patterns in the large tributaries on the eastern side of the basin. A comparison of results for total phosphorus for the two separate decades of analysis found that more tributaries had decreasing concentrations and flux rates in the second decade than the first. An overall reduction in dissolved phosphorus flux of 0.7 t/yr was seen in the Lake Champlain Basin during the full period of analysis. That very small net change in flux reflects substantial reductions between 1990 and 2000 from eastern tributaries, especially in Otter Creek and the LaPlatte and Winooski

  14. Trends `91

    SciTech Connect

    1992-12-31

    This is a source book of frequently used global change data. This second article expands the coverage of sites recording atmospheric concentrations of carbon dioxide and methane and updates records previously reported.

  15. Concentration, flux, and the analysis of trends of total and dissolved phosphorus, total nitrogen, and chloride in 18 tributaries to Lake Champlain, Vermont and New York, 1990–2011

    USGS Publications Warehouse

    Medalie, Laura

    2013-01-01

    Annual concentration, flux, and yield for total phosphorus, dissolved phosphorus, total nitrogen, and chloride for 18 tributaries to Lake Champlain were estimated for 1990 through 2011 using a weighted regression method based on time, tributary streamflows (discharges), and seasonal factors. The weighted regression method generated two series of daily estimates of flux and concentration during the period of record: one based on observed discharges and a second based on a flow-normalization procedure that removes random variation due to year-to-year climate-driven effects. The flownormalized estimate for a given date is similar to an average estimate of concentration or flux that would be made if all of the observed discharges for that date were equally likely to have occurred. The flux bias statistic showed that 68 of the 72 flux regression models were minimally biased. Temporal trends in the concentrations and fluxes were determined by calculating percent changes in flow-normalized annual fluxes for the full period of analysis (1990 through 2010) and for the decades 1990–2000 and 2000–2010. Basinwide, flow-normalized total phosphorus flux decreased by 42 metric tons per year (t/yr) between 1990 and 2010. This net result reflects a basinwide decrease in flux of 21 metric tons (t) between 1990 and 2000, followed by a decrease of 20 t between 2000 and 2010; both results were largely influenced by flux patterns in the large tributaries on the eastern side of the basin. A comparison of results for total phosphorus for the two separate decades of analysis found that more tributaries had decreasing concentrations and flux rates in the second decade than the first. An overall reduction in dissolved phosphorus flux of 0.7 t/yr was seen in the Lake Champlain Basin during the full period of analysis. That very small net change in flux reflects substantial reductions between 1990 and 2000 from eastern tributaries, especially in Otter Creek and the LaPlatte and Winooski

  16. Future trends.

    PubMed

    Friedberg, Richard C; Weiss, Ronald L

    2007-12-01

    Several current forces have set anticipated future changes in health care in motion, or, at least, have set the stage for change. End-consumer demand increasingly drives the market; as a result, entire businesses are transforming or emerging anew to meet these demands. In general, consumers demand high quality at reasonable cost, to be delivered as fast as possible with minimal inconvenience. The health care consumer takes this expectation further, to include the desire for all helpful information regarding one's health to be made readily available for him/her to make the best decision and minimize morbidity, mortality, misdiagnosis, and inconvenience. This article addresses the impact upon the laboratory by considering four key interrelated dynamics that affect these trends: market, medicine, technology, and information systems. PMID:17950906

  17. Fertilizer trends

    SciTech Connect

    Donaldson, R.

    1992-01-01

    This fourteenth edition of Fertilizer Trends presents historical fertilizer market data to aid industry, government, and financial market analysis and planners in their study of fertilizer and agricultural market cycles, market planning, and investment decisions. A 27-year summary of the US fertilizer market is presented in graphic and tabular form. Production, use, and trade data are included for each plant nutrient and sulfur. Canadian statistics have been included because of the important role of the Canadian fertilizer industry in the US fertilizer market. World production and consumption of nitrogen, phosphate, and potash are included because of the strong influence of world markets on the domestic market. Planted acreage and plant nutrient application rates for the major crops have been included to illustrate their effect on fertilizer use. Retail prices of the leading US fertilizer materials also are given.

  18. Fertilizer trends

    SciTech Connect

    Donaldson, R.

    1992-12-31

    This fourteenth edition of Fertilizer Trends presents historical fertilizer market data to aid industry, government, and financial market analysis and planners in their study of fertilizer and agricultural market cycles, market planning, and investment decisions. A 27-year summary of the US fertilizer market is presented in graphic and tabular form. Production, use, and trade data are included for each plant nutrient and sulfur. Canadian statistics have been included because of the important role of the Canadian fertilizer industry in the US fertilizer market. World production and consumption of nitrogen, phosphate, and potash are included because of the strong influence of world markets on the domestic market. Planted acreage and plant nutrient application rates for the major crops have been included to illustrate their effect on fertilizer use. Retail prices of the leading US fertilizer materials also are given.

  19. Quality control of mitigation methods for unusually high indoor radon concentrations.

    PubMed

    Huber, J; Ennemoser, O; Schneider, P

    2001-08-01

    The present study's objective was to control the quality of different mitigation methods for unusually high indoor radon (222Rn) concentrations of up to 274,000 Bq m(-3) in a village (Umhausen, 2,600 inhabitants) in western Tyrol, Austria. Five years after mitigation, five different remedial actions were examined on their quality by means of measuring indoor radon concentrations with charcoal liquid scintillation radon detectors and with a continuously recording AlphaGuard detector. Mitigation method in house 1--a mechanical intake and outlet ventilation system with heat exchanger in the basement, combined with a soil depressurization system--was characterized by long-term stability. With most favorable air pressure (+100 Pa) in the basement, mean basement radon concentrations in the winter were reduced from 200,000 Bq m(-3) to 3,000 Bq m(-3) by this method 5 y after mitigation. Acting against experts' instructions, the inhabitants had switched off the ventilation system most of the time to minimize power consumption although it had been proven that ventilation reduced mean basement radon concentration by a factor of about 3 in the winter and about 15 in the summer. Mitigation method in house 2-soil depressurization with two fans and loops of drainage tubes to withdraw radon from the region below the floor and outside the basement walls, and from soil below that part of the house with no basement-had been the most successful remedial measure until the winter of 1999 (i.e., 6 y after mitigation), when micro-cracks opened and consequently mean basement radon concentration increased from 250 Bq m(-3) to 1,500 Bq m(-3). Measures to block these microcracks and to minimize soil drying are being developed. Five years after mitigation, the remedial method used in house 3--a multilayer floor construction, where a fan was used to suck radon from a layer between bottom slab and floor-reduced winter mean radon concentration from 25,000 Bq m(-3) to 1,200 Bq m(-3), with the

  20. MERCURY DEPOSITION AND LAKE QUALITY TRENDS

    EPA Science Inventory

    Watershed factors influence the differing trends in mercury residue levels. Fish mercury concentrations show positive correlations with water color, methylmercury concentrations, and plankton mercury, and negative correlations with pH and alkalinity.

  1. Trends in Environmental Analysis

    SciTech Connect

    Koester, C J; Moulik, A

    2005-03-31

    This article discusses developments in environmental analytical chemistry that occurred in the years of 2003 and 2004. References were found by searching the ''Science Citation Index and Current Contents''. As in our review of two years ago (A1), techniques are highlighted that represent current trends and state-of-the-art technologies in the sampling, extraction, separation, and detection of trace concentrations, low-part-per-billion and less, of organic, inorganic, and organometallic contaminants in environmental samples. New analytes of interest are also reviewed, the detections of which are made possible by recently developed analytical instruments and methods.

  2. Detection of radon emission at the edges of lunar maria with the Apollo alpha-particle spectrometer

    NASA Technical Reports Server (NTRS)

    Gorenstein, P.; Golub, L.; Bjorkholm, P.

    1974-01-01

    The distribution of radioactive polonium-210, a decay product of radon-222, shows enhanced concentrations at the edges of lunar maria. Enhancements are seen at the edges of Mare Fecunditatis, Mare Crisium, Mare Smythii, Mare Tranquillitatis, Mare Nubium, Mare Cognitum, and Oceanus Procellarum. The observation is indicative of the transient emission of radon gas from the perimeters of lunar maria.

  3. Hydrogeology, Aquifer Geochemistry, and Ground-Water Quality in Morgan County, West Virginia

    USGS Publications Warehouse

    Boughton, Carol J.; McCoy, Kurt J.

    2006-01-01

    Private and public wells throughout Morgan County, W. Va., were tested to determine aquifer hydraulic, geochemical, and water-quality characteristics. The entire study area is located in the Valley and Ridge Physiographic Province, a region of complex geologic structure and lithology. Aquifers in the study area are characterized by thin to thick bedded formations with interbedding among the various limestones, shales, sandstones, and siltstones that are folded into a series of steeply dipping north-south trending anticlines and synclines. Zones of ground-water production typically consist of one to two fracture sets, with little to no production from unfractured bedrock matrix. Measurements of transmissivity range from 2 to 1,490 feet squared per day, with the larger transmissivities occurring near bedding contacts and in zones with cross-faulting or jointing. Ground water flows from recharge areas in the uplands to local drainages and to deeper flow systems that appear to be controlled by regional geologic structure. The overall flow direction is from south to north within the study area. Ground water within the study area is predominantly a calcium-bicarbonate type water reflecting contact with carbonate rocks. Sodium-bicarbonate and calcium-magnesium-sulfate end-members also exist, with many samples exhibiting mixing, which may be the result of flow between the differing rock types or within units containing both carbonate rocks and shales. Values of water-quality characteristics that were greater than U.S. Environmental Protection Agency drinking-water standards included radon-222, pH, turbidity, iron, manganese, aluminum, and total- and fecal-coliform and Escherichia coli (E. coli) bacteria. Concentrations of radon-222 were detected in all samples from all units, with the largest concentrations (1,330 and 2,170 picocuries per liter) from the Clinton Formation.

  4. Mediterranean Ocean Colour Chlorophyll Trends.

    PubMed

    Colella, Simone; Falcini, Federico; Rinaldi, Eleonora; Sammartino, Michela; Santoleri, Rosalia

    2016-01-01

    In being at the base of the marine food web, phytoplankton is particularly important for marine ecosystem functioning (e.g., biodiversity). Strong anthropization, over-exploitation of natural resources, and climate change affect the natural amount of phytoplankton and, therefore, represent a continuous threat to the biodiversity in marine waters. In particular, a concerning risks for coastal waters is the increase in nutrient inputs of terrestrial/anthropogenic origin that can lead to undesirable modifications of phytoplankton concentration (i.e., eutrophication). Monitoring chlorophyll (Chl) concentration, which is a proxy of phytoplankton biomass, is an efficient tool for recording and understanding the response of the marine ecosystem to human pressures and thus for detecting eutrophication. Here, we compute Chl trends over the Mediterranean Sea by using satellite data, also highlighting the fact that remote sensing may represent an efficient and reliable solution to synoptically control the "good environmental status" (i.e., the Marine Directive to achieve Good Environmental Status of EU marine waters by 2020) and to assess the application of international regulations and environmental directives. Our methodology includes the use of an ad hoc regional (i.e., Mediterranean) algorithm for Chl concentration retrieval, also accounting for the difference between offshore (i.e., Case I) and coastal (i.e., Case II) waters. We apply the Mann-Kendall test and the Sens's method for trend estimation to the Chl concentration de-seasonalized monthly time series, as obtained from the X-11 technique. We also provide a preliminary analysis of some particular trends by evaluating their associated inter-annual variability. The high spatial resolution of our approach allows a clear identification of intense trends in those coastal waters that are affected by river outflows. We do not attempt to attribute the observed trends to specific anthropogenic events. However, the trends

  5. Mediterranean Ocean Colour Chlorophyll Trends

    PubMed Central

    Colella, Simone; Falcini, Federico; Rinaldi, Eleonora; Sammartino, Michela; Santoleri, Rosalia

    2016-01-01

    In being at the base of the marine food web, phytoplankton is particularly important for marine ecosystem functioning (e.g., biodiversity). Strong anthropization, over-exploitation of natural resources, and climate change affect the natural amount of phytoplankton and, therefore, represent a continuous threat to the biodiversity in marine waters. In particular, a concerning risks for coastal waters is the increase in nutrient inputs of terrestrial/anthropogenic origin that can lead to undesirable modifications of phytoplankton concentration (i.e., eutrophication). Monitoring chlorophyll (Chl) concentration, which is a proxy of phytoplankton biomass, is an efficient tool for recording and understanding the response of the marine ecosystem to human pressures and thus for detecting eutrophication. Here, we compute Chl trends over the Mediterranean Sea by using satellite data, also highlighting the fact that remote sensing may represent an efficient and reliable solution to synoptically control the “good environmental status” (i.e., the Marine Directive to achieve Good Environmental Status of EU marine waters by 2020) and to assess the application of international regulations and environmental directives. Our methodology includes the use of an ad hoc regional (i.e., Mediterranean) algorithm for Chl concentration retrieval, also accounting for the difference between offshore (i.e., Case I) and coastal (i.e., Case II) waters. We apply the Mann-Kendall test and the Sens’s method for trend estimation to the Chl concentration de-seasonalized monthly time series, as obtained from the X-11 technique. We also provide a preliminary analysis of some particular trends by evaluating their associated inter-annual variability. The high spatial resolution of our approach allows a clear identification of intense trends in those coastal waters that are affected by river outflows. We do not attempt to attribute the observed trends to specific anthropogenic events. However, the

  6. Constraints for Using Radon-in-Water Concentrations as an Indicator for Groundwater Discharge into Surface Water Bodies

    NASA Astrophysics Data System (ADS)

    Petermann, Eric; Schubert, Michael

    2015-04-01

    The radon (222-Rn) activity concentration of surface water is a favourable indicator for the detection of groundwater discharge into surface water bodies since radon is highly enriched in groundwater relative to surface waters. Hence, positive radon-in-water anomalies are interpreted as groundwater discharge locations. For this approach, usually, radon time-series are recorded along transects in near-surface waters. Time-series of radon-in-water concentration are commonly measured by permanent radon extraction from a water pump stream and continuous monitoring of the resulting radon-in-air concentration by means of a suitable radon detector. Radon-in-water concentrations are derived from the recorded radon-in-air signal by making allowances for water/air partitioning of radon. However, several constraints arise for this approach since undesirable factors are influencing the radon-in-water concentration. Consequently, corrections are required to remove the effect of these undesirable factors from the radon signal. First, an instrument inherent response delay between actual changes in the radon-in-water concentration and the related radon-in-air signal was observed during laboratory experiments. The response delay is due to (i) the water/air transfer kinetics of radon and (ii) the delayed decay equilibrium between radon and its progeny polonium (218-Po), which is actually being measured by most radon-in-air monitors. We developed a physical model, which considers all parameters that are responsible for the response delay. This model allows the reconstruction of radon-in-water time-series based on radon-in-air records. Second, on a time-scale of several hours the tidal stage is known as a major driver for groundwater discharge fluctuations due to varying hydraulic gradients between groundwater and surface water during a tidal cycle. Consequently, radon-in-water time-series that are detected on tidal coasts are not comparable among each other without normalization

  7. Trends in nutrients

    USGS Publications Warehouse

    Heathwaite, A.L.; Johnes, P.J.; Peters, N.E.

    1996-01-01

    The roles of nitrogen (N) and phosphorus (P) as key nutrients determining the trophic status of water bodies are examined, and evidence reviewed for trends in concentrations of N and P species which occur in freshwaters, primarily in northern temperate environments. Data are reported for water bodies undergoing eutrophication and acidification, especially water bodies receiving increased nitrogen inputs through the atmospheric deposition of nitrogen oxides (NOx). Nutrient loading on groundwaters and surface freshwaters is assessed with respect to causes and rates of (change, relative rates of change for N and P, and implications of change for the future management of lakes, rivers and groundwaters. In particular, the nature and emphasis of studies for N species and P fractions in lakes versus rivers and groundwaters are contrasted. This review paper primarily focuses on results from North America and Europe, particularly for the UK where a wide range of data sets exists. Few nutrient loading data have been published on water bodies in less developed countries; however, some of the available data are presented to provide a global perspective. In general, N and P concentrations have increased dramatically (>20 times background concentrations) in many areas and causes vary considerably, ranging from urbanization to changes in agricultural practices.

  8. Drivers, Trends and Mitigation

    SciTech Connect

    Blanco, Arthur S.; Gerlagh, Reyer; Suh, Sangwon; Barrett, John A.; de Coninck, Heleen; Diaz Morejon, Cristobal Felix; Mathur, Ritu; Nakicenovic, Nebojsa; Ahenkorah, Alfred Ofosu; Pan, Jiahua; Pathak, Himanshu; Rice, Jake; Richels, Richard G.; Smith, Steven J.; Stern, David; Toth, Ferenc L.; Zhou, Peter

    2014-12-01

    Chapter 5 analyzes the anthropogenic greenhouse gas (GHG) emission trends until the present and the main drivers that explain those trends. The chapter uses different perspectives to analyze past GHG-emissions trends, including aggregate emissions flows and per capita emissions, cumulative emissions, sectoral emissions, and territory-based vs. consumption-based emissions. In all cases, global and regional trends are analyzed. Where appropriate, the emission trends are contextualized with long-term historic developments in GHG emissions extending back to 1750.

  9. Trend Analyses of Nitrate in Danish Groundwater

    NASA Astrophysics Data System (ADS)

    Hansen, B.; Thorling, L.; Dalgaard, T.; Erlandsen, M.

    2012-04-01

    This presentation assesses the long-term development in the oxic groundwater nitrate concentration and nitrogen (N) loss due to intensive farming in Denmark. Firstly, up to 20-year time-series from the national groundwater monitoring network enable a statistically systematic analysis of distribution, trends and trend reversals in the groundwater nitrate concentration. Secondly, knowledge about the N surplus in Danish agriculture since 1950 is used as an indicator of the potential loss of N. Thirdly, groundwater recharge CFC (Chlorofluorocarbon) age determination allows linking of the first two dataset. The development in the nitrate concentration of oxic groundwater clearly mirrors the development in the national agricultural N surplus, and a corresponding trend reversal is found in groundwater. Regulation and technical improvements in the intensive farming in Denmark have succeeded in decreasing the N surplus by 40% since the mid 1980s while at the same time maintaining crop yields and increasing the animal production of especially pigs. Trend analyses prove that the youngest (0-15 years old) oxic groundwater shows more pronounced significant downward nitrate trends (44%) than the oldest (25-50 years old) oxic groundwater (9%). This amounts to clear evidence of the effect of reduced nitrate leaching on groundwater nitrate concentrations in Denmark. Are the Danish groundwater monitoring strategy obtimal for detection of nitrate trends? Will the nitrate concentrations in Danish groundwater continue to decrease or are the Danish nitrate concentration levels now appropriate according to the Water Framework Directive?

  10. Mediterranean Ocean Colour Chlorophyll trend

    NASA Astrophysics Data System (ADS)

    rinaldi, eleonora; colella, simone; santoleri, rosalia

    2014-05-01

    Monitoring chlorophyll (Chl) concentration, seen as a proxy for phytoplankton biomass, is an efficient tool in order to understand the response of marine ecosystem to human pressures. This is particularly important along the coastal regions, in which the strong anthropization and the irrational exploitation of resources represent a persistent threat to the biodiversity. The aim of this work is to assess the effectiveness and feasibility of using Ocean Color (OC) data to monitor the environmental changes in Mediterranean Sea and to develop a method for detecting trend from OC data that can constitute a new indicator of the water quality within the EU Marine Strategy Framework Directive implementation. In this study the Mediterranean merged Case1-Case2 chlorophyll product, produced by CNR-ISAC and distributed in the framework of MyOcean, is analyzed. This product is obtained by using two different bio-optical algorithms for open ocean (Case1) and coastal turbid (Case2) waters; this improves the quality of the Chl satellite estimates, especially near the coast. In order to verify the real capability of the this product for estimating Chl trend and for selecting the most appropriated statistical test to detect trend in the Mediterranean Sea, a comparison between OC and in situ data are carried out. In-situ Chl data are part of the European Environment Information and Observation Network (Eionet) of the European Environmental Agency (EEA). Four different statistical approaches to estimate trend have been selected and used to compare trend values obtained with in-situ and OC data. Results show that the best agreement between in-situ and OC trend is achieved using the Mann- Kendall test. The Mediterranean trend map obtained applying this test to the de-seasonalized OC time series shows that, in accordance with the results of many authors, the case 1 waters of Mediterranean sea are characterized by a negative trend. However, the most intense trend signals, both negative

  11. Historical ground-water-flow patterns and trends in iron concentrations in the Potomac--Raritan--Magothy aquifer system in parts of Philadelphia, Pennsylvania, and Camden and Gloucester Counties, New Jersey

    USGS Publications Warehouse

    Sloto, Ronald A.

    2003-01-01

    The Potomac-Raritan-Magothy (PRM) aquifer system is an important sole-source ground-water supply in Camden and Gloucester Counties, N.J. Elevated iron concentrations are a persistent water-quality problem associated with ground water from the PRM. In Philadelphia, the PRM no longer is usable as a water supply because of highly elevated concentrations of iron (as high as 429 mg/L [milligrams per liter]), manganese (as high as 4 mg/L), and sulfate (as high as 1,720 mg/L). A strongly reducing environment in the PRM in south Philadelphia causes these constituents to be remobilized by reductive dissolution of the aquifer matrix. By the 1920s, ground-water pumping changed the natural ground-water-flow patterns, and ground water flowed toward pumping centers in Philadelphia. By 1940, recharge areas changed from the topographically high areas east of Trenton, N.J., to the outcrop area of the PRM in Philadelphia, and the Delaware River became a source of recharge instead of a point of ground-water discharge. By 1954, the cone of depression caused by pumping at the former Philadelphia Naval Ship Yard (PNSY) exceeded 50 feet below NGVD 29, and the direction of ground-water flow was from New Jersey toward Philadelphia. Because of highly elevated concentrations of iron and manganese, pumping at the former PNSY ceased in the mid-1960s. Beginning about 1951, increased ground-water withdrawals from the PRM in New Jersey reversed the hydraulic gradient so that ground-water flow was from Philadelphia toward New Jersey under the Delaware River, making Philadelphia a recharge area for the PRM aquifer system in parts of Camden and Gloucester Counties. By 1988, water levels in the lower aquifer of the PRM in New Jersey had declined to 103 feet below NAVD 88. In 1943, dissolved iron concentrations ranged from 0.07 to 0.6 mg/L at the former PNSY. By 1967 when the wells at the PNSY were abandoned, dissolved iron concentrations had reached 46 mg/L. Dissolved iron concentrations in water

  12. Marketing Trends to Watch

    ERIC Educational Resources Information Center

    Circle, Alison

    2009-01-01

    This article identifies 13 cultural trends that libraries can turn into opportunites to reach patrons. These trends include: Twitter, online reputation management, value added content, mobile marketing, and emotional connection.

  13. Trends in Education.

    ERIC Educational Resources Information Center

    School Planning & Management, 2002

    2002-01-01

    Several architects, planners, administrators, and contractors answer questions about trends related to school construction, interior design, business, security, and technology. Trends concern funding issues, specialized designs, planning for safety, technological integration, and equity in services. (EV)

  14. Trends In Satellite Communication

    NASA Technical Reports Server (NTRS)

    Poley, William A.; Stevens, Grady H.; Stevenson, Steven M.; Lekan, Jack; Arth, Clifford H.; Hollansworth, James E.; Miller, Edward F.

    1988-01-01

    Report assesses trends in satellite communication from present to year 2010. Examines restrictions imposed by limited spectrum resource and technology needs created by trends. Personal communications, orbiting switchboards, and videophones foreseen.

  15. Radon ( 222Rn) level variations on a regional scale from the Singhbhum Shear Zone, India: A comparative evaluation between influence of basement U-activity and porosity

    NASA Astrophysics Data System (ADS)

    Banerjee, K. S.; Basu, A.; Guin, R.; Sengupta, D.

    2011-05-01

    This paper is devoted to the comparative study of the radon flux vs. uranium content and radon flux vs. porosity for mineral samples from some typical Indian rocks (schists, quartzites, argillaceous quartzites, slates and granites) used as building materials, primarily around the Singhbhum Shear Zone, Jharkhand State. As the radon flux of any particular rock type was investigated with reference to its uranium activity and porosity, a good concordance of porosity on radon flux was observed. Such a significant influence of porosity on radon flux was also observed when different rock types were inter-compared. For example, granite that is commonly considered as typical source of indoor radon showed depleted level of radon flux when compared to most other rocks in the study area. In case of rocks such as slates and argillaceous quartzites, low porosity exhibited reduced radon flux in spite of their enhanced radioactive source content. It is concluded that it may not be advisable to utilize materials that are uranium depleted for construction purposes without giving importance to the materials' porosity.

  16. Groundwater discharge to wetlands driven by storm and flood events: Quantification using continuous Radon-222 and electrical conductivity measurements and dynamic mass-balance modelling

    NASA Astrophysics Data System (ADS)

    Gilfedder, B. S.; Frei, S.; Hofmann, H.; Cartwright, I.

    2015-09-01

    The dynamic response of groundwater discharge to external influences such as rainfall is an often neglected part of water and solute balances in wetlands. Here we develop a new field platform for long-term continuous 222Rn and electrical conductivity (EC) measurements at Sale Wetland, Australia to study the response of groundwater discharge to storm and flood events. The field measurements, combined with dynamic mass-balance modelling, demonstrate that the groundwater flux can increase from 3 to ∼20 mm d-1 following storms and up to 5 mm d-1 on the receding limb of floods. The groundwater pulses are likely produced by activation of local groundwater flow paths by water ponding on the surrounding flood plains. While 222Rn is a sensitive tracer for quantifying transient groundwater discharge, the mass-balance used to estimate fluxes is sensitive to parameterisation of gas exchange (k) with the atmosphere. Comparison of six equations for calculating k showed that, based on parameterisation of k alone, the groundwater flux estimate could vary by 58%. This work shows that neglecting transient processes will lead to errors in water and solute flux estimates based on infrequent point measurements. This could be particularly important for surface waters connected to contaminated or saline groundwater systems.

  17. A global numerical study of radon-222 and lead-210 in the atmosphere using the AES and York University CDT General Circulation Model (AYCG)

    NASA Technical Reports Server (NTRS)

    Beagley, Stephen R.; Degrandpre, Jean; Mcconnell, John C.; Laprise, Rene; Mcfarlane, Norman

    1994-01-01

    The Canadian Climate Center (CCC) GCM has been modified to allow its use for studies in atmospheric chemistry. The initial experiments reported here have been run to test and allow sensitivity studies of the new transport module. The impact of different types of parameterization for the convective mixing have been studied based on the large scale evolution of Rn-222 and Pb-210. Preliminary results have shown that the use of a scheme, which mixes unstable columns over a very short time scale, produces a global distribution of lead that agrees in some aspects with observations. The local impact of different mixing schemes on a short lived tracer like the radon is very important.

  18. Source term characterisation using concentration trends and geochemical associations of Pb and Zn in river sediments in the vicinity of a disused mine site: implications for contaminant metal dispersion processes.

    PubMed

    Pulford, Ian D; MacKenzie, Angus B; Donatello, Shane; Hastings, Laura

    2009-05-01

    River sediment at a disused lead-zinc mine was analysed to provide an understanding of the chemical nature of the source term for contaminated sediment exported from the site. Changes in concentration and geochemical associations of Pb and Zn were measured using aqua regia digestion and the BCR sequential extraction procedure. Sediment in the immediate vicinity of the mine was highly contaminated with Pb (max. c. 11,000 mg kg(-1)) and Zn (max. c. 30,000 mg kg(-1)), but these values declined rapidly within 1 km of the mine due to dilution and hydraulic sorting. Lead fractionation changed from being predominantly in the reducible fraction to being in the acetic acid-extractable fraction, whereas Zn was predominantly in the residual fraction. This material is transported as fine sediment in the river system.

  19. Regional Kendall test for trend

    USGS Publications Warehouse

    Helsel, D.R.; Frans, L.M.

    2006-01-01

    Trends in environmental variables are often investigated within a study region at more than one site. At each site, a trend analysis determines whether a trend has occurred. Yet often also of interest is whether a consistent trend is evident throughout the entire region. This paper adapts the Seasonal Kendall trend test to determine whether a consistent regional trend occurs in environmental variables.

  20. Elliptical concentrators.

    PubMed

    Garcia-Botella, Angel; Fernandez-Balbuena, Antonio Alvarez; Bernabeu, Eusebio

    2006-10-10

    Nonimaging optics is a field devoted to the design of optical components for applications such as solar concentration or illumination. In this field, many different techniques have been used to produce optical devices, including the use of reflective and refractive components or inverse engineering techniques. However, many of these optical components are based on translational symmetries, rotational symmetries, or free-form surfaces. We study a new family of nonimaging concentrators called elliptical concentrators. This new family of concentrators provides new capabilities and can have different configurations, either homofocal or nonhomofocal. Translational and rotational concentrators can be considered as particular cases of elliptical concentrators. PMID:17068595

  1. Some Current Population Trends.

    ERIC Educational Resources Information Center

    Taeuber, Conrad

    Population trends in the 1960's and early 1970's are examined in this 1972 speech in terms of overall national trends, the growth of metropolitan areas, the rural population, geographic shifts, internal migration, the black population, and living arrangements. It is noted that population growth in the 1960's was unevenly distributed within age…

  2. General Achievement Trends: Oklahoma

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  3. General Achievement Trends: Georgia

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  4. General Achievement Trends: Nebraska

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  5. General Achievement Trends: Arkansas

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  6. General Achievement Trends: Maryland

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  7. General Achievement Trends: Maine

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  8. General Achievement Trends: Iowa

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  9. General Achievement Trends: Texas

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  10. General Achievement Trends: Hawaii

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  11. General Achievement Trends: Kansas

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  12. General Achievement Trends: Florida

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  13. General Achievement Trends: Massachusetts

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  14. General Achievement Trends: Tennessee

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  15. General Achievement Trends: Alabama

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  16. General Achievement Trends: Virginia

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  17. General Achievement Trends: Michigan

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  18. General Achievement Trends: Colorado

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  19. Trends Shaping Education 2010

    ERIC Educational Resources Information Center

    OECD Publishing (NJ3), 2010

    2010-01-01

    "Trends Shaping Education 2010" brings together evidence showing the effects on education of globalisation, social challenges, changes in the workplace, the transformation of childhood, and ICT. To make the content accessible, each trend is presented on a double page, containing an introduction, two charts with brief descriptive text and a set of…

  20. Trend Book, 2004

    ERIC Educational Resources Information Center

    Maryland Higher Education Commission, 2004

    2004-01-01

    This document presents an assortment of statistical data about Maryland postsecondary education. The information is presented for a period of years, so that trends can be highlighted. The Trend Book is organized into nine sections: (1) Factors Affecting Enrollments; (2) Enrollment; (3) Retention, Transfer and Graduation; (4) Degrees; (5) Graduate…

  1. Trend analyses with river sediment rating curves

    USGS Publications Warehouse

    Warrick, Jonathan A.

    2015-01-01

    Sediment rating curves, which are fitted relationships between river discharge (Q) and suspended-sediment concentration (C), are commonly used to assess patterns and trends in river water quality. In many of these studies it is assumed that rating curves have a power-law form (i.e., C = aQb, where a and b are fitted parameters). Two fundamental questions about the utility of these techniques are assessed in this paper: (i) How well to the parameters, a and b, characterize trends in the data? (ii) Are trends in rating curves diagnostic of changes to river water or sediment discharge? As noted in previous research, the offset parameter, a, is not an independent variable for most rivers, but rather strongly dependent on b and Q. Here it is shown that a is a poor metric for trends in the vertical offset of a rating curve, and a new parameter, â, as determined by the discharge-normalized power function [C = â (Q/QGM)b], where QGM is the geometric mean of the Q values sampled, provides a better characterization of trends. However, these techniques must be applied carefully, because curvature in the relationship between log(Q) and log(C), which exists for many rivers, can produce false trends in â and b. Also, it is shown that trends in â and b are not uniquely diagnostic of river water or sediment supply conditions. For example, an increase in â can be caused by an increase in sediment supply, a decrease in water supply, or a combination of these conditions. Large changes in water and sediment supplies can occur without any change in the parameters, â and b. Thus, trend analyses using sediment rating curves must include additional assessments of the time-dependent rates and trends of river water, sediment concentrations, and sediment discharge.

  2. Skin Cancer Trends

    MedlinePlus

    ... Indian/Alaska Native men. Remained level among Asian/Pacific Islander men. Women Increased significantly by 1.4% ... Indian/Alaska Native women. Remained level among Asian/Pacific Islander women. Mortality Trends From 2003 to 2012 ...

  3. Breast Cancer Trends

    MedlinePlus

    ... significantly by 1.1% per year among Asian/Pacific Islander women. Mortality Trends From 2003 to 2012 ... significantly by 1.4% per year among Asian/Pacific Islander women. Data source: Ryerson AB, Eheman CR, ...

  4. Lung Cancer Trends

    MedlinePlus

    ... significantly by 1.8% per year among Asian/Pacific Islander men. Women Decreased significantly by 0.9% ... Indian/Alaska Native women. Remained level among Asian/Pacific Islander women. Mortality Trends From 2003 to 2012 ...

  5. Trends in stratospheric temperature

    NASA Technical Reports Server (NTRS)

    Schoeberl, M. R.; Newman, P. A.; Rosenfield, J. E.; Angell, J.; Barnett, J.; Boville, B. A.; Chandra, S.; Fels, S.; Fleming, E.; Gelman, M.

    1989-01-01

    Stratospheric temperatures for long-term and recent trends and the determination of whether observed changes in upper stratospheric temperatures are consistent with observed ozone changes are discussed. The long-term temperature trends were determined up to 30mb from radiosonde analysis (since 1970) and rocketsondes (since 1969 and 1973) up to the lower mesosphere, principally in the Northern Hemisphere. The more recent trends (since 1979) incorporate satellite observations. The mechanisms that can produce recent temperature trends in the stratosphere are discussed. The following general effects are discussed: changes in ozone, changes in other radiatively active trace gases, changes in aerosols, changes in solar flux, and dynamical changes. Computations were made to estimate the temperature changes associated with the upper stratospheric ozone changes reported by the Solar Backscatter Ultraviolet (SBUV) instrument aboard Nimbus-7 and the Stratospheric Aerosol and Gas Experiment (SAGE) instruments.

  6. Ozone Trend Detectability

    NASA Technical Reports Server (NTRS)

    Campbell, J. W. (Editor)

    1981-01-01

    The detection of anthropogenic disturbances in the Earth's ozone layer was studied. Two topics were addressed: (1) the level at which a trend in total ozoning is detected by existing data sources; and (2) empirical evidence in the prediction of the depletion in total ozone. Error sources are identified. The predictability of climatological series, whether empirical models can be trusted, and how errors in the Dobson total ozone data impact trend detectability, are discussed.

  7. Airborne pollen trends in the Iberian Peninsula.

    PubMed

    Galán, C; Alcázar, P; Oteros, J; García-Mozo, H; Aira, M J; Belmonte, J; Diaz de la Guardia, C; Fernández-González, D; Gutierrez-Bustillo, M; Moreno-Grau, S; Pérez-Badía, R; Rodríguez-Rajo, J; Ruiz-Valenzuela, L; Tormo, R; Trigo, M M; Domínguez-Vilches, E

    2016-04-15

    Airborne pollen monitoring is an effective tool for studying the reproductive phenology of anemophilous plants, an important bioindicator of plant behavior. Recent decades have revealed a trend towards rising airborne pollen concentrations in Europe, attributing these trends to an increase in anthropogenic CO2 emissions and temperature. However, the lack of water availability in southern Europe may prompt a trend towards lower flowering intensity, especially in herbaceous plants. Here we show variations in flowering intensity by analyzing the Annual Pollen Index (API) of 12 anemophilous taxa across 12 locations in the Iberian Peninsula, over the last two decades, and detecting the influence of the North Atlantic Oscillation (NAO). Results revealed differences in the distribution and flowering intensity of anemophilous species. A negative correlation was observed between airborne pollen concentrations and winter averages of the NAO index. This study confirms that changes in rainfall in the Mediterranean region, attributed to climate change, have an important impact on the phenology of plants.

  8. Trends in stratospheric minor constituents

    NASA Technical Reports Server (NTRS)

    Stolarski, R. S.; Chu, W. P.; Coffey, M. T.; Heaps, W. S.; Kaye, J. A.; Mccormick, M. P.; Zander, R.

    1989-01-01

    Photochemical models predict that increasing source gas concentrations are also expected to lead to changes in the concentrations of both catalytically active radical species (such as NO2, ClO, and OH) and inactive reservoir species (such as HNO3, HCl, and H2O). For simplicity, we will refer to all these as trace species. Those species that are expected to have increasing concentration levels are investigated. Additionally, the trace species concentration levels are monitored for unexpected changes on the basis of the measure increase in source gases. Carrying out these investigations is difficult due to the limited data base of measurements of stratospheric trace species. In situ measurements are made only infrequently, and there are few satelliteborne measurements, most over a time space insufficient for trend determination. Instead, ground-based measurements of column content must be used for many species, and interpretation is complicated by contributions from the troposphere or mesosphere or both. In this chapter, we examine existing measurements as published or tabulated.

  9. Groundwater quality in the Chemung River, Eastern Lake Ontario, and Lower Hudson River Basins, New York, 2013

    USGS Publications Warehouse

    Scott, Tia-Marie; Nystrom, Elizabeth A.; Reddy, James E.

    2015-11-10

    The Lower Hudson River Basin study area covers 5,607 square miles and encompasses the part of the Lower Hudson River Basin that lies within New York plus the parts of the Housatonic, Hackensack, Bronx, and Saugatuck River Basins that are in New York. Twelve of the wells sampled in the Lower Hudson River Basin are completed in sand-and-gravel deposits, and 13 are completed in bedrock. Groundwater in the Lower Hudson River Basin was generally of good quality, although properties and concentrations of some constituents—pH, sodium, chloride, dissolved solids, arsenic, aluminum, iron, manganese, radon-222, total coliform bacteria, fecal coliform bacteria, Escherichia coli bacteria, and heterotrophic plate count—equaled or exceeded primary, secondary, or proposed drinking-water standards. The constituent most frequently detected in concentrations exceeding drinking-water standards (20 of 25 samples) was radon-222.

  10. European drought trends

    NASA Astrophysics Data System (ADS)

    Gudmundsson, L.; Seneviratne, S. I.

    2015-06-01

    Recent climate projections suggest pronounced changes in European drought frequency. In the north, increased precipitation volumes are likely to reduce drought occurrence, whereas more frequent droughts are expected for southern Europe. To assess whether this pattern of changes in drought frequency can already be identified for the past decades, we analyse trends in a recently developed pan-European drought climatology that is based on the Standardized Precipitation Index (SPI). The index is derived on multiple time scales, ranging from 1 to 36 months, which allows the assessment of trends in both short term and multi-year droughts. Trends are quantified using the Theil-Sen trend estimator combined with an extension of the Mann-Kendal test (p < 0.05) that accounts for serial correlation. Field significance is assessed on the basis of techniques that control the false discovery rate in a multiple testing setting. The trend analysis indicates that changes in drought frequency are more pronounced on time scales of one year and longer. The analysis also reveals that there has been a tendency for decreased drought frequency in northern Europe in the past decades, whereas droughts have likely become more frequent in selected southern regions.

  11. Concentrating Radioactivity

    ERIC Educational Resources Information Center

    Herrmann, Richard A.

    1974-01-01

    By concentrating radioactivity contained on luminous dials, a teacher can make a high reading source for classroom experiments on radiation. The preparation of the source and its uses are described. (DT)

  12. Surface radioactivity resulting from the deposition of /sup 222/Rn daughter products

    SciTech Connect

    Lively, R.S.; Ney, E.P.

    1987-04-01

    This paper describes the relationship between the /sup 222/Rn in air, and the level of surface radioactivity that results from the build-up and decay of the daughter isotope, /sup 210/Pb. Samples of /sup 222/Rn were collected from Mystery Cave, which is located in southeastern Minnesota and from the basement of a house in Minneapolis, MN. Lead-210 was measured on surfaces within the cave, on a rock removed from the cave, and on a basement window. Surface alpha activities were measured on the rock sample and on the window. Radon-222 concentrations in the cave air ranged from 3 to 13 kBq m-3. In the basement, /sup 222/Rn levels were between 0.2 and 0.4 kBq m-3. Virtually all the surface radioactivity resulted from the deposition and decay of airborne /sup 222/Rn daughter products and was not produced by the decay of U in the rock. Radon-222 concentrations in the cave air were almost 30 times higher than in the basement air; however, the surface /sup 210/Pb activity in the cave was 100 times higher than that in the basement. This suggests that in the cave air, /sup 222/Rn daughter products are more likely to reach the walls and decay to /sup 210/Pb. The measurements of surface alpha activity did not show a similar trend primarily because /sup 210/Pb had diffused further into the coating of dirt on the rock than into the glass of the window. The resulting surface activity of the rock was lower than expected based on the /sup 210/Pb concentration, because many of the alpha-emitting nuclei were at depths beyond the range of emitted alpha particles. On surfaces where the penetration range of alpha particles is greater than the diffusion depth of /sup 210/Pb atoms, either the /sup 210/Pb concentration or surface alpha-activity measurements should provide estimates of average long-term /sup 222/Rn concentrations.

  13. Nutrient Trends in Streams and Rivers of the United States, 1993-2003

    USGS Publications Warehouse

    Sprague, Lori A.; Mueller, David K.; Schwarz, Gregory E.; Lorenz, David L.

    2009-01-01

    Trends in streamflow and concentrations and loads of total phosphorus, total nitrogen, and nitrate were determined for the period from 1993 to 2003 in selected streams and ricers of the United States. Flow-adjusted trends in concentration (the trends that would have occurred in the absence of natural chances in streamflow), non-flow-adjusted trends in concentration (the trends resulting from both natural and human factors), and trends in load (trends in the nutrient mass transported downstream) were determined, and the results were examined spatially to determine whether a consistent pattern of trends occurred across groups of sites at multiple locations. Relations between the trends and changes in nutrient sources and streamflow are examined. See document for complete abstract.

  14. Some fighter aircraft trends

    NASA Technical Reports Server (NTRS)

    Spearman, L.

    1985-01-01

    Some basic trends in fighters are traced from the post World II era. Beginning with the first operational jet fighter, the P-80, the characteristics of subsequent fighter aircraft are examined for performance, mission capability, effectiveness, and cost. Characteristics presented include: power loading, wing loading, maximum speed, rate of climb, turn rate, weight and weight distribution, cost and cost distribution. The characteristics of some USSR aircraft are included for comparison. The trends indicate some of the rationale for certain fighter designs and some likely characteristics to be sought in future fighter aircraft designs.

  15. Recent Trends in the Structure of the Cable Television Industry.

    ERIC Educational Resources Information Center

    Perry, Martin

    After a brief review of the growth of cable television from 1948 to 1965, the paper examines in more detail trends in the structure of the industry since 1965. Specifically, interest revolves around the apparent trends of concentration and vertical integration within the industry. Corporate histories of the leading firms are then used to…

  16. Data Concentrator

    NASA Technical Reports Server (NTRS)

    Willett, Mike

    2015-01-01

    Orbital Research, Inc., developed, built, and tested three high-temperature components for use in the design of a data concentrator module in distributed turbine engine control. The concentrator receives analog and digital signals related to turbine engine control and communicates with a full authority digital engine control (FADEC) or high-level command processor. This data concentrator follows the Distributed Engine Controls Working Group (DECWG) roadmap for turbine engine distributed controls communication development that operates at temperatures at least up to 225 C. In Phase I, Orbital Research developed detailed specifications for each component needed for the system and defined the total system specifications. This entailed a combination of system design, compiling existing component specifications, laboratory testing, and simulation. The results showed the feasibility of the data concentrator. Phase II of this project focused on three key objectives. The first objective was to update the data concentrator design modifications from DECWG and prime contractors. Secondly, the project defined requirements for the three new high-temperature, application-specific integrated circuits (ASICs): one-time programmable (OTP), transient voltage suppression (TVS), and 3.3V. Finally, the project validated each design by testing over temperature and under load.

  17. Temperature trends in the midlatitude summer mesosphere

    NASA Astrophysics Data System (ADS)

    Lübken, F.-J.; Berger, U.; Baumgarten, G.

    2013-12-01

    We have performed trend studies in the mesosphere in the period 1961-2009 with Leibniz-Institute Middle Atmosphere (LIMA) model driven by European Centre for Medium-Range Weather Forecasts reanalysis below approximately 40 km and adapts temporal variations of CO2 and O3 according to observations. Temperatures in the mesosphere/lower thermosphere vary nonuniformly with time, mainly due to the influence of O3. Here we analyze the contribution of varying concentrations of CO2 and O3 to the temperature trend in the mesosphere. It is important to distinguish between trends on pressure altitudes, zp, and geometrical altitudes, zgeo, where the latter includes the effect of shrinking due to cooling at lower heights. For the period 1961-2009, temperature trends on geometrical and pressure altitudes can differ by as much as -0.9 K/dec in the mesosphere. Temperature trends reach approximately -1.3±0.11 K/dec at zp˜60 km and -1.8±0.18 K/dec at zgeo˜70 km, respectively. CO2 is the main driver of these trends in the mesosphere, whereas O3 contributes approximately one third, both on geometrical and pressure heights. Depending on the time period chosen, linear temperature trends can vary substantially. Altitudes of pressure levels in the mesosphere decrease by up to several hundred meters. We have performed long-term runs with LIMA applying twentieth century reanalysis dating back to 1871. Again, trends are nonuniform with time. Since the late nineteenth century, temperatures in the mesosphere have dropped by approximately 5-7 K on pressure altitudes and up to 10-12 K on geometrical altitudes.

  18. Trends and Issues.

    ERIC Educational Resources Information Center

    Orey, Michael; Sullivan, Michael; Molenda, Michael; Foley, Anne L.; Morgan, Janet; McKenney, Susan; Harada, Violet H.; Lee, Jung

    2003-01-01

    Contains five articles covering general trends and issues in instructional technology, including: developments in corporate training, higher education, and K-12 education; women's contributions to the leading instructional technology journals; developing science education materials via computer-based support; learning in the Information Age; and…

  19. Five Trends for Schools

    ERIC Educational Resources Information Center

    Lapkoff, Shelley; Li, Rose Maria

    2007-01-01

    The authors look at important demographic trends that will have an effect on schools, including roller-coaster enrollments and increasing diversity. For example, compared with 10 years ago, the average child entering a U.S. school today is less likely to live in a family with two married parents but is more likely to have a living grandparent,…

  20. Trends in Biomedical Education.

    ERIC Educational Resources Information Center

    Peppas, Nicholas A.; Mallinson, Richard G.

    1982-01-01

    An analysis of trends in biomedical education within chemical education is presented. Data used for the analysis included: type/level of course, subjects taught, and textbook preferences. Results among others of the 1980 survey indicate that 28 out of 79 schools responding offer at least one course in biomedical engineering. (JN)

  1. Language Trends 2010 Secondary

    ERIC Educational Resources Information Center

    CILT, the National Centre for Languages, 2010

    2010-01-01

    The Language Trends survey is run jointly each year by CILT, the National Centre for Languages, the Association for Language Learning (ALL) and the Independent Schools Modern Languages Association (ISMLA). In this period of rapid change and policy development, it is vital to have an up to date picture of current issues for languages. Therefore,…

  2. Trends in Interior Environments.

    ERIC Educational Resources Information Center

    Hovey, Robyn

    2000-01-01

    Examines how an understanding of interior design trends can help planners address their present and future furniture needs. Examines how new types of construction and their associated concerns are requiring new approaches from the facility designers and manufacturers of product solutions. (GR)

  3. Ten Top Tech Trends

    ERIC Educational Resources Information Center

    McLester, Susan

    2008-01-01

    In this article, the author discusses the major technical issues, products, and practices of the day. The top ten tech trends are listed and discussed. These include: (1) data mining; (2) cyberbullying; (3) 21st century skills; (4) digital content; (5) learning at leisure; (6) personal responders; (7) mobile tools; (8) bandwidth; (9) open-source…

  4. Trends in Schoolhouse Construction.

    ERIC Educational Resources Information Center

    Reida, George W.

    Much material has been written, printed, and published on trends in schoolhouse construction but many of the experts have not bothered to concern themselves in carefully analyzing and understanding the program which is to be housed or the specific needs of the children in the community. In discussing this subject, two distinct realities must be…

  5. Locker Room Design Trends.

    ERIC Educational Resources Information Center

    Wiens, Janet

    2001-01-01

    Examines how today's college and university athletic locker rooms have become sophisticated recruiting tools that rival many professional facilities. Locker room design and location and their level of furniture, finishes, and equipment are discussed as is the trend for more environmentally friendly locker rooms. (GR)

  6. Trends in Copyright.

    ERIC Educational Resources Information Center

    Becker, Gary H.

    1993-01-01

    Reviews trends in copyright law, including changes resulting from technological advances that include audio and video tape recordings, motion pictures, photocopying equipment, CD-ROM, and multimedia; amendments to the law, including administrative issues; compensation to authors of computer software programs; court cases; and a movement toward…

  7. Trends & Indicators: Enrollment Period

    ERIC Educational Resources Information Center

    Harney, John O.

    2011-01-01

    Since New England Board of Higher Education (NEBHE) began publishing tables and charts exploring "Trends & Indicators" in New England higher education more than a half-century ago, few figures have grabbed as much attention as college "enrollment" data. These local, state, regional and national data go beyond simple headcounts of students going to…

  8. Trends Reshaping Colleges.

    ERIC Educational Resources Information Center

    Campbell, Dale F.; Peek, Roger C.

    2002-01-01

    Examines current educational trends in the community colleges, based on critical issues addressed at the 2002 Community College Futures Assembly (CCFA) in Orlando, Florida. Describes the CCFA as an independent policy forum, sponsored by the University of Florida, that convenes annually. Discusses the top three critical issues presented: the needs…

  9. Marketing for Camp Trends.

    ERIC Educational Resources Information Center

    Biddle, Alicia

    1998-01-01

    To effectively market a camp, current trends and issues must be considered: specialty programming, the Americans With Disabilities Act, competing recreational programs, changes in the school year, programming for seniors, and accountability. Camps should have a marketing strategy that includes public relations, a marketing plan, a pricing…

  10. Trends in Educational Expenditure.

    ERIC Educational Resources Information Center

    Burke, Gerald

    This study provides an overview of expenditures for education and training by educational institutions in Australia, 1991-2001. The study used newly available data from the Australian Bureau of Statistics (ABS) and administrative data from the main sectors' reports on the size and trends in public and private education expenditures. It analyzed…

  11. Detection of earthquake induced radon precursors by Hilbert Huang Transform

    NASA Astrophysics Data System (ADS)

    Barman, Chiranjib; Ghose, Debasis; Sinha, Bikash; Deb, Argha

    2016-10-01

    Continuous measurement of radon-222 concentration in soil was carried out across duration of one year at a geologically faulted area having high regional heat flow to detect anomalies caused by seismic activities. The data reveals a range of periodicities present in the radon time series. To identify seismic induced radon changes we treat the time series data through various filtering methods to remove inherent periodicities. The Ensemble Empirical Mode Decomposition (EEMD) is deployed to decompose the signal into its characteristic modes. Hilbert Huang Transform (HHT) is applied for the first time on the physically significant modes obtained by EEMD to represent time-energy-frequency of the recorded soil radon time series. After removing the periodic and quasi-periodic constituents from the original time series, the simulated result shows a forceful correlation in recorded radon-222 anomalies with regional and local seismic events.

  12. Trend analysis of weekly acid rain data, 1978-83

    USGS Publications Warehouse

    Schertz, Terry L.; Hirsch, Robert M.

    1985-01-01

    There are 19 stations in the National Atmospheric Deposition Program which operated over the period 1978-83 and were subsequently incorporated into the National Trends Network in 1983. The precipitation chemistry data for these stations for this period were analyzed for trend, spatial correlation, seasonality, and relationship to precipitation volume. The intent of the analysis was to provide insights on the sources of variation in precipitation chemistry and to attempt to ascertain what statistical procedures may be most useful for ongoing analysis of the National Trends Network data. The Seasonal Kendall test was used for detection of trends in raw concentrations of dissolved constituents, pH and specific conductance, and residuals of these parameters from regression analysis. Forty-one percent of the trends detected in the raw concentrations were downtrends, 4 percent were uptrends, and 55 percent showed no trends at a = 0.2. At a more restrictive significance level of a = 0.05, 24 percent of the trends detected were downtrends, 2 percent were uptrends, and 74 percent showed no trends. The two constituents of greatest interest in terms of human generated emissions and environmental effects, sulfate and nitrate, showed only downtrends, and sulfate showed the largest decreases in concentration per year of all the ions tested.

  13. Ozone and temperature trends

    NASA Technical Reports Server (NTRS)

    Stolarski, Richard S.; Fioletov, Vitali; Bishop, Lane; Godin, Sophie; Bojkov, Rumen D.; Kirchhoff, Volker; Chanin, Marie-Lise; Zawodny, Joseph M.; Zerefos, Christos S.; Chu, William

    1991-01-01

    An update of the extensive reviews of the state of knowledge of measured ozone trends published in the Report of the International Ozone Trends Panel is presented. The update contains a review of progress since these reports, including reviewing of the ozone records, in most cases through March 1991. Also included are some new, unpublished reanalyses of these records including a complete reevaluation of 29 stations located in the former Soviet Union. The major new advance in knowledge of the measured ozone trend is the existence of independently calibrated satellite data records from the Total Ozone Mapping Spectrometer (TOMS) and Stratospheric Aerosol and Gas Experiment (SAG) instruments. These confirm many of the findings, originally derived from the Dobson record, concerning northern mid-latitude changes in ozone. We now have results from several instruments, whereas the previously reported changes were dependent on the calibration of a single instrument. This update will compare the ozone records from many different instruments to determine whether or not they provide a consistent picture of the ozone change that has occurred in the atmosphere. The update also briefly considers the problem of stratospheric temperature change. As in previous reports, this problem received significantly less attention, and the report is not nearly as complete. This area needs more attention in the future.

  14. Ozone trends and their relationship to characteristic weather patterns.

    PubMed

    Austin, Elena; Zanobetti, Antonella; Coull, Brent; Schwartz, Joel; Gold, Diane R; Koutrakis, Petros

    2015-01-01

    Local trends in ozone concentration may differ by meteorological conditions. Furthermore, the trends occurring at the extremes of the Ozone distribution are often not reported even though these may be very different than the trend observed at the mean or median and they may be more relevant to health outcomes. Classify days of observation over a 16-year period into broad categories that capture salient daily local weather characteristics. Determine the rate of change in mean and median O3 concentrations within these different categories to assess how concentration trends are impacted by daily weather. Further examine if trends vary for observations in the extremes of the O3 distribution. We used k-means clustering to categorize days of observation based on the maximum daily temperature, standard deviation of daily temperature, mean daily ground level wind speed, mean daily water vapor pressure and mean daily sea-level barometric pressure. The five cluster solution was determined to be the appropriate one based on cluster diagnostics and cluster interpretability. Trends in cluster frequency and pollution trends within clusters were modeled using Poisson regression with penalized splines as well as quantile regression. There were five characteristic groupings identified. The frequency of days with large standard deviations in hourly temperature decreased over the observation period, whereas the frequency of warmer days with smaller deviations in temperature increased. O3 trends were significantly different within the different weather groupings. Furthermore, the rate of O3 change for the 95th percentile and 5th percentile was significantly different than the rate of change of the median for several of the weather categories.We found that O3 trends vary between different characteristic local weather patterns. O3 trends were significantly different between the different weather groupings suggesting an important interaction between changes in prevailing weather

  15. Ozone trends and their relationship to characteristic weather patterns.

    PubMed

    Austin, Elena; Zanobetti, Antonella; Coull, Brent; Schwartz, Joel; Gold, Diane R; Koutrakis, Petros

    2015-01-01

    Local trends in ozone concentration may differ by meteorological conditions. Furthermore, the trends occurring at the extremes of the Ozone distribution are often not reported even though these may be very different than the trend observed at the mean or median and they may be more relevant to health outcomes. Classify days of observation over a 16-year period into broad categories that capture salient daily local weather characteristics. Determine the rate of change in mean and median O3 concentrations within these different categories to assess how concentration trends are impacted by daily weather. Further examine if trends vary for observations in the extremes of the O3 distribution. We used k-means clustering to categorize days of observation based on the maximum daily temperature, standard deviation of daily temperature, mean daily ground level wind speed, mean daily water vapor pressure and mean daily sea-level barometric pressure. The five cluster solution was determined to be the appropriate one based on cluster diagnostics and cluster interpretability. Trends in cluster frequency and pollution trends within clusters were modeled using Poisson regression with penalized splines as well as quantile regression. There were five characteristic groupings identified. The frequency of days with large standard deviations in hourly temperature decreased over the observation period, whereas the frequency of warmer days with smaller deviations in temperature increased. O3 trends were significantly different within the different weather groupings. Furthermore, the rate of O3 change for the 95th percentile and 5th percentile was significantly different than the rate of change of the median for several of the weather categories.We found that O3 trends vary between different characteristic local weather patterns. O3 trends were significantly different between the different weather groupings suggesting an important interaction between changes in prevailing weather

  16. Ozone Trends and their Relationship to Characteristic Weather Patterns

    PubMed Central

    Austin, Elena; Zanobetti, Antonella; Coull, Brent; Schwartz, Joel; Gold, Diane; Koutrakis, Petros

    2016-01-01

    Background Local trends in ozone concentration may differ by meteorological conditions. Furthermore, the trends occurring at the extremes of the Ozone distribution are often not reported even though these may be very different than the trend observed at the mean or median and they may be more relevant to health outcomes. Aims Classify days of observation over a 16 year period into broad categories that capture salient daily local weather characteristics. Determine the rate of change in mean and median O3 concentrations within these different categories to assess how concentration trends are impacted by daily weather. Further examine if trends vary for observations in the extremes of the O3 distribution. Methods We used k-means clustering to categorize days of observation based on the maximum daily temperature, standard deviation of daily temperature, mean daily ground level wind speed, mean daily water vapor pressure and mean daily sea-level barometric pressure. The five cluster solution was determined to be the appropriate one based on cluster diagnostics and cluster interpretability. Trends in cluster frequency and pollution trends within clusters were modeled using Poisson regression with penalized splines as well as quantile regression. Results There were five characteristic groupings identified. The frequency of days with large standard deviations in hourly temperature decreased over the observation period, whereas the frequency of warmer days with smaller deviations in temperature increased. O3 trends were significantly different within the different weather groupings. Furthermore, the rate of O3 change for the 95th percentile and 5th percentile was significantly different than the rate of change of the median for several of the weather categories. Conclusions We found that O3 trends vary between different characteristic local weather patterns. O3 trends were significantly different between the different weather groupings suggesting an important interaction

  17. Nutrient and Suspended-Sediment Trends in the Missouri River Basin, 1993-2003

    USGS Publications Warehouse

    Sprague, Lori A.; Clark, Melanie L.; Rus, David L.; Zelt, Ronald B.; Flynn, Jennifer L.; Davis, Jerri V.

    2007-01-01

    Trends in streamflow and concentration of total nitrogen, nitrite plus nitrate, ammonia, total phosphorus, orthophosphorus, and suspended sediment were determined for the period from 1993 to 2003 at selected stream sites in the Missouri River Basin. Flow-adjusted trends in concentration (the trends that would have occurred in the absence of natural changes in streamflow) and non-flow-adjusted trends in concentration (the overall trends resulting from natural and human factors) were determined. In the analysis of flow-adjusted trends, the removal of streamflow as a variable affecting concentration allowed trends caused by other factors such as implementation of best management practices to be identified. In the analysis of non-flow-adjusted trends, the inclusion of any and all factors affecting concentration allowed trends affecting aquatic ecosystems and the status of streams relative to water-quality standards to be identified. Relations between the flow-adjusted and non-flow-adjusted trends and changes in streamflow, nutrient sources, ground-water inputs, and implementation of management practices also were examined to determine the major factors affecting the trends. From 1993 to 2003, widespread downward trends in streamflow indicated that drought conditions from about 2000 to 2003 led to decreasing streamflow throughout much of the Missouri River Basin. Flow-adjusted trends in nitrite plus nitrate and ammonia concentrations were split nearly equally between nonsignificant and downward; at about one-half of the sites, management practices likely were contributing to measurable decreases in concentrations of nitrite plus nitrate and ammonia. Management practices had less of an effect on concentrations of total nitrogen; downward flow-adjusted trends in total nitrogen concentrations occurred at only 2 of 19 sites. The pattern of non-flow-adjusted trends in nitrite plus nitrate concentrations was similar to the pattern of flow-adjusted trends; non

  18. Short-term Aerosol Trends: Reality or Myth?

    NASA Technical Reports Server (NTRS)

    Leptoukh, Gregory; Zubko, Viktor

    2009-01-01

    The main questions addressed in this slide presentation involve short-term trends of MODIS aerosol optical thickness (AOT) over 6 years: (1) Why are the trends different in different regions? (2) How are these trends so high? (3) Why are they "coherent" in many areas? (4) Are these changes in aerosol concentrations real, i.e., are they monotonic changes in emissions? Several views of the Spatial Distribution of AOT from Terra are shown. In conclusion there are several trends: (1) There is a broad spatial inhomogenueity in AOT trends over 6 years of MODIS Terra and Aqua (2) Some of the areas demonstrate clear positive trends related to increase of emission (e.g., Eastern China) (3) Strong trends in some other areas are superficial and might be attributed, in part, to: (3a) Least squares linear trend sensitivity to outliers (need to use more robust linear fitting method) (3b) Spatial and temporal shifts or trends in meteorological conditions, especially in wind patterns responsible for aerosol transport (6) Aerosol trends should be studied together with changes in meteorology patterns as they might closely linked together

  19. Construction Trends Dictate Vital Skills.

    ERIC Educational Resources Information Center

    Polivchak, Philip

    1989-01-01

    Vocational education can provide opportunities for students by anticipating trends. Four trends in the construction industry are (1) remodeling, (2) building and apartment maintenance, (3) quality, and (4) smart houses. (JOW)

  20. Emerging Trends in Higher Education.

    ERIC Educational Resources Information Center

    Mayville, Zari

    This literature survey examines trends in higher education requiring a broad base of support from the changing institutions and the people who have to respond to, plan for, and manage the changes. Trends are identified in the areas of enrollment, financial aid, curricula, faculty, financial status, and assessment. Trends affecting enrollment…

  1. Trends in PET imaging

    SciTech Connect

    Moses, William W.

    2000-11-01

    Positron Emission Tomography (PET) imaging is a well established method for obtaining information on the status of certain organs within the human body or in animals. This paper presents an overview of recent trends PET instrumentation. Significant effort is being expended to develop new PET detector modules, especially those capable of measuring depth of interaction. This is aided by recent advances in scintillator and pixellated photodetector technology. The other significant area of effort is development of special purpose PET cameras (such as for imaging breast cancer or small animals) or cameras that have the ability to image in more than one modality (such as PET / SPECT or PET / X-Ray CT).

  2. Application trends for photovoltaics

    NASA Astrophysics Data System (ADS)

    Macomber, H. L.

    This paper presents the results of studies by MONEGON to develop forecasts of PV system application markets. These forecasts consider economic factors such as conventional energy costs now and in the future, the relationship between world economic conditions, as represented by each country's Gross National Product, and energy demand; the cost potential for PV systems technologies; and the application trends in the past and future. The application sectors analyzed are: remote, stand-alone systems; residential systems; service/commercial/industrial/institutional; and central utility systems. An overall market forecast is developed and this forecast is segmented into the four market sectors.

  3. Solar concentrator

    SciTech Connect

    Smyth, J.S.

    1982-06-08

    A solar concentrator having an open framework formed as a geodesic dome. A rotatable support axle extends substantially diametrically across the dome and has the opposite ends thereof supported on the framework. The support axle defines a first rotational axis which is oriented to extend substantially parallel with the earth's north-south axis. A support post is hingedly mounted on the support shaft substantially at the midpoint thereof for permitting angular displacement of the support post relative to the support shaft about a second rotational axis which is perpendicular to the first axis. A dishshaped reflector assembly is positioned within the interior of the framework and fixedly secured to the support post. First and second drives effect angular displacement of the reflector assembly about the first and second axes, respectively, to permit tracking of the solar position.

  4. Pesticide trends in major rivers of the United States, 1992-2010

    USGS Publications Warehouse

    Ryberg, Karen R.; Vecchia, Aldo V.; Gilliom, Robert J.; Martin, Jeffrey D.

    2014-01-01

    This report is part of a series of pesticide trend assessments led by the National Water-Quality Assessment Program of the U.S. Geological Survey. This assessment focuses on major rivers of various sizes throughout the United States that have large watersheds with a range of land uses, changes in pesticide use, changes in management practices, and natural influences typical of the regions being drained. Trends were assessed at 59 sites for 40 pesticides and pesticide degradates during each of three overlapping periods: 1992–2001, 1997–2006, and 2001–10. In addition to trends in concentration, trends in agricultural-use intensity (agricultural use) were also assessed at 57 of the sites for 35 parent compounds with agricultural uses during the same three periods. The SEAWAVE-Q model was used to analyze trends in concentration, and parametric survival regression for interval-censored data was used to assess trends in agricultural use. All trends are provided in downloadable electronic files. A subset of 39 sites was chosen to represent non-nested, generally independent basins for a national analysis of pesticide and agricultural-use trends for the most prevalent pesticides (15 pesticides and 2 degradation products). Graphical and numerical results are presented to provide a national overview of concentration and use trends. As another perspective on understanding pesticide concentration trends in large rivers in relation to multiple tributary watersheds, this report also presents a detailed assessment of concentration and use trends for simazine, metolachlor, atrazine, deethylatrazine, and diazinon for a set of 17 nested sites in the Mississippi River Basin (including the Ohio and Missouri River Basins), for the second and third trend periods. Pesticides strongly dominated by agricultural use—cyanazine, metolachlor, atrazine, and alachlor—had widespread agreement between concentration trends and agricultural-use trends. Pesticides with substantial use in

  5. Land Cover Trends Project

    USGS Publications Warehouse

    Acevedo, William

    2006-01-01

    The Land Cover Trends Project is designed to document the types, rates, causes, and consequences of land cover change from 1973 to 2000 within each of the 84 U.S. Environmental Protection Agency (EPA) Level III ecoregions that span the conterminous United States. The project's objectives are to: * Develop a comprehensive methodology using probability sampling and change analysis techniques and Landsat Multispectral Scanner (MSS), Thematic Mapper (TM), and Enhanced Thematic Mapper (ETM) data for estimating regional land cover change. * Characterize the spatial and temporal characteristics of conterminous U.S. land cover change for five periods from 1973 to 2000 (nominally 1973, 1980, 1986, 1992, and 2000). * Document the regional driving forces and consequences of change. * Prepare a national synthesis of land cover change.

  6. Trends in Cochlear Implants

    PubMed Central

    Zeng, Fan-Gang

    2004-01-01

    More than 60,000 people worldwide use cochlear implants as a means to restore functional hearing. Although individual performance variability is still high, an average implant user can talk on the phone in a quiet environment. Cochlear-implant research has also matured as a field, as evidenced by the exponential growth in both the patient population and scientific publication. The present report examines current issues related to audiologic, clinical, engineering, anatomic, and physiologic aspects of cochlear implants, focusing on their psychophysical, speech, music, and cognitive performance. This report also forecasts clinical and research trends related to presurgical evaluation, fitting protocols, signal processing, and postsurgical rehabilitation in cochlear implants. Finally, a future landscape in amplification is presented that requires a unique, yet complementary, contribution from hearing aids, middle ear implants, and cochlear implants to achieve a total solution to the entire spectrum of hearing loss treatment and management. PMID:15247993

  7. Temperature trend biases

    NASA Astrophysics Data System (ADS)

    Venema, Victor; Lindau, Ralf

    2016-04-01

    In an accompanying talk we show that well-homogenized national dataset warm more than temperatures from global collections averaged over the region of common coverage. In this poster we want to present auxiliary work about possible biases in the raw observations and on how well relative statistical homogenization can remove trend biases. There are several possible causes of cooling biases, which have not been studied much. Siting could be an important factor. Urban stations tend to move away from the centre to better locations. Many stations started inside of urban areas and are nowadays more outside. Even for villages the temperature difference between the centre and edge can be 0.5°C. When a city station moves to an airport, which often happened around WWII, this takes the station (largely) out of the urban heat island. During the 20th century the Stevenson screen was established as the dominant thermometer screen. This screen protected the thermometer much better against radiation than earlier designs. Deficits of earlier measurement methods have artificially warmed the temperatures in the 19th century. Newer studies suggest we may have underestimated the size of this bias. Currently we are in a transition to Automatic Weather Stations. The net global effect of this transition is not clear at this moment. Irrigation on average decreases the 2m-temperature by about 1 degree centigrade. At the same time, irrigation has increased significantly during the last century. People preferentially live in irrigated areas and weather stations serve agriculture. Thus it is possible that there is a higher likelihood that weather stations are erected in irrigated areas than elsewhere. In this case irrigation could lead to a spurious cooling trend. In the Parallel Observations Science Team of the International Surface Temperature Initiative (ISTI-POST) we are studying influence of the introduction of Stevenson screens and Automatic Weather Stations using parallel measurements

  8. Socioeconomic trends in radiology.

    PubMed

    Barneveld Binkhuysen, F H

    1998-01-01

    For radiology the socioeconomic environment is a topic of increasing importance. In addition to the well-known important scientific developments in radiology such as interventional MRI, several other major trends can be recognized: (1) changes in the delivery of health care, in which all kinds of managed care are developing and will influence the practice of radiology, and (2) the process of computerization and digitization. The socioeconomic environment of radiology will be transformed by the developments in managed care, teleradiology and the integration of information systems. If radiologists want to manage future radiology departments they must have an understanding of the changes in the fields of economics and politics that are taking place and that will increasingly influence radiology. Some important and recognizable aspects of these changes will be described here. PMID:9477292

  9. Non-parametric trend analysis of water quality data of rivers in Kansas

    USGS Publications Warehouse

    Yu, Y.-S.; Zou, S.; Whittemore, D.

    1993-01-01

    Surface water quality data for 15 sampling stations in the Arkansas, Verdigris, Neosho, and Walnut river basins inside the state of Kansas were analyzed to detect trends (or lack of trends) in 17 major constituents by using four different non-parametric methods. The results show that concentrations of specific conductance, total dissolved solids, calcium, total hardness, sodium, potassium, alkalinity, sulfate, chloride, total phosphorus, ammonia plus organic nitrogen, and suspended sediment generally have downward trends. Some of the downward trends are related to increases in discharge, while others could be caused by decreases in pollution sources. Homogeneity tests show that both station-wide trends and basinwide trends are non-homogeneous. ?? 1993.

  10. Finding forced trends in oceanic oxygen

    NASA Astrophysics Data System (ADS)

    Long, Matthew C.; Deutsch, Curtis; Ito, Taka

    2016-02-01

    Anthropogenically forced trends in oceanic dissolved oxygen are evaluated in Earth system models in the context of natural variability. A large ensemble of a single Earth system model is used to clearly identify the forced component of change in interior oxygen distributions and to evaluate the magnitude of this signal relative to noise generated by internal climate variability. The time of emergence of forced trends is quantified on the basis of anomalies in oxygen concentrations and trends. We find that the forced signal should already be evident in the southern Indian Ocean and parts of the eastern tropical Pacific and Atlantic basins; widespread detection of forced deoxygenation is possible by 2030-2040. In addition to considering spatially discrete metrics of detection, we evaluate the similarity of the spatial structures associated with natural variability and the forced trend. Outside of the subtropics, these patterns are not wholly distinct on the isopycnal surfaces considered, and therefore, this approach does not provide significantly advanced detection. Our results clearly demonstrate the strong impact of natural climate variability on interior oxygen distributions, providing an important context for interpreting observations.

  11. MERCURY DEPOSITION AND WATER QUALITY TRENDS IN THE UPPER MIDWEST, USA

    EPA Science Inventory

    Watershed factors influence the differing trends in mercury residue levels. Fish mercury concentrations show positive correlations with water color, methylmercury concentrations, and plankton mercury, and negative correlations with pH and alklinity.

  12. Trends in Stream Water Quality in the Southeastern United States

    NASA Astrophysics Data System (ADS)

    Harned, D. A.; Staub, E. L.; Peak, K. L.

    2007-12-01

    As part of the U.S Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Program water-quality data for 253 streams in 8 states of the Southeastern United States were assessed for trends from 1973-2005. Forty-three USGS sampling sites were examined for trends over multiple periods within 1973-2005 in measures of pH, specific conductance, and dissolved oxygen; and in concentrations of dissolved solids, suspended sediment, chloride, sodium, sulfate, silica, potassium, carbon, total nitrogen, total ammonia, total ammonia plus organic nitrogen, dissolved nitrite plus nitrate, and total phosphorus. An additional 210 sites from the U.S. Environmental Protection Agency STORET database were tested for trends in total nitrogen and total phosphorus concentrations over the 1975-2004 and 1993-2004 periods. The seasonal Kendall test or Tobit regression was used to detect monotonic trends. Concentrations of dissolved constituents have increased in many streams in the Southeast over the last 30 years. Specific conductance, an indicator of dissolved ions in water, increased in the Southeast in 26 USGS sites over the long term, but showed fewer increases in the 1993-2004 period. The pH increased at 11 of the 43 USGS sites in the Southeast from 1975 to 1985. Fewer trends in pH are apparent for 1993-2004. Concentrations of phosphorus in streams in the Southeast have decreased over the last 35 years coinciding with phosphate detergent bans and improvements in waste-water treatment that were implemented beginning in 1972. Sixteen of the 17 long-term trends in phosphorus concentrations detected at the 43 USGS sites were decreasing. Twenty-seven of the 32 long-term (1975-2004) trends detected in total phosphorus concentrations at the 210 STORET sites were decreasing. Nitrogen trends the Southeast are mixed. Decreasing trends in total nitrogen observed at USGS sites from 1975 to 1995 are not apparent during 1993-2004. Of the 18 recent (1993-2004) trends in total nitrogen

  13. Trends in reservoir simulation

    SciTech Connect

    Nolen, J.S.

    1995-06-01

    The future of reservoir simulation is driven by two different and, on the surface, paradoxical trends. On the one hand, the user base is on average becoming less experienced, and on the other, increasingly complex models are being built to honor the advances in reservoir-description technology. The job of the software development community is to create software that satisfies both the ease-of-use needs of the novice and the accuracy needs of the integrated geoscience team. One of the near-term effects of these demands will be to improve the capabilities and quality of the fully integrated geoscience work-station. This will include the need for implementation of industry-wide data standards. Reservoir simulators will need to incorporate increasing amounts of interactivity and built-in expertise. Accuracy of results will be improved by increased use of unstructured grids, including automatic gridding software with dynamic capabilities. Additional research will focus on complex wells, including both in-flow performance and wellbore hydraulics. Finally, grid size will continue to escalate in step with advances in hardware and software. The growth of grid size will be mitigated by substantial efforts in upscaling, but ultimately parallel computing must provide the mechanism for continued growth.

  14. Trends in cardiac metastasis.

    PubMed

    Karwinski, B; Svendsen, E

    1989-11-01

    A review of 8571 autopsies disclosed 2833 patients with malignant tumours from 1975 to 1984 at the Department of Pathology, The Gade Institute. Cardiac metastases were found in 130 cases. An increase of cardiac involvement was shown in the autopsy material from 1.2% in 1975-1979 to 1.8% in 1980-1984. The same trend was seen if cardiac metastases were related to malignant tumours. Numerically, lung cancer accounted for most of the metastases seen, but the increase was made up by other tumours than lung cancer. especially malignant melanoma, mesothelioma, breast cancer and sarcomas. These tumours have a high frequency of heart metastases and the increased incidence of these cancers in the material explains the rise of cardiac metastases. Cardiac metastases increased with rising number of distant metastases. This study shows that mesotheliomas have the highest percentage of cardiac spread. The importance of autopsy for detecting metastatic spread in sites that are difficult to detect clinically is emphasized.

  15. Biosensors: recent trends.

    PubMed

    Graham, A; Moo-Young, M

    1985-01-01

    One of the major bottlenecks in automation and process control of industrial bioprocesses is the lack of suitable sensing devices to accurately measure the concentrations of biomolecules. The measurement of ions (e.g., H(+), NH(4)(+)) and gases (e.g., O(2), CO(2), NH(3)) using standard ion-selective and gas sensing electrodes respectively, is well established. Chemical analysis of biomolecules off-line is generally unreliable, labour intensive and may lead to contamination of the biological systems. Problems of maintaining sterile conditions are especially important when dealing with slow growing mammalian or plant cells in culture. Active research in the development of biosensors for monitoring fermentation processes, food production and pollution control, and for medical and veterinary applications is currently underway. This paper reviews recent approaches toward the development of biosensors which involve a biochemical interaction to measure the concentrations of biomolecules, primarily for the on-line monitoring and control of fermentation processes.

  16. The Geomagnetic Control Concept of The Ionospheric Long- Term Trends

    NASA Astrophysics Data System (ADS)

    Mikhailov, A. V.

    The geomagnetic control concept has been developed to explain long-term trends of the electron concentration in the F2 and E ionospheric regions. Periods with negative and positive foF2, hmF2 and foE trends correspond to the periods of increasing or decreasing geomagnetic activity with the turning points around the end of 1950s, 1960s, and 1980s where trends change their signs. Strong latitudinal and diurnal variations revealed for the foF2 and hmF2 trends can be explained by neutral composition, temperature and thermospheric wind changes. Particle precipitation is important in the auroral zone. The newly proposed concept proceeds from a natural origin of the F2-layer trends rather than an artificial one related to the greenhouse effect. Using the proposed method a very long-term foF2 and foE trends related with general increase of geomagnetic activity in the 20th century has been revealed for the first time. The firstly revealed relationship of the foE trends with geomagnetic activity is due to nitric oxide variations at the E-region heights. This "natural" relationship of the foE trends with geomagnetic activity breaks down around 1970 on many stations presumably due to chemical polution of the upper atmosphere. The increasing rate of rocket and satellite launchings in the late 1960s is considered as a reason.

  17. Trends in surface ozone over Europe, 1978-1990

    NASA Technical Reports Server (NTRS)

    Low, Pak Sum; Kelly, P. Michael; Davies, Trevor D.

    1994-01-01

    It has been suggested that surface ozone concentrations in rural areas of Europe have been increasing at a rate of 1 to 3 percent per year over the past two to three decades, presumably due to human influences (Feister and Warmbt, 1987; Bojkov, 1988; Penkett, 1989). Recently, we have analyzed surface ozone data from 20 European stations of differing character (remote, rural, suburban and urban) for a common period of 1978-1988 (Low et al., 1992). It was found that there were pronounced annual and seasonal variations in the linear trends in different areas, and there was no dominant region-wide trend. In spring and, most notably, summer, stations on the maritime fringe of the network generally exhibited negative trends whilst those located further into the continental interior exhibited positive trends. In winter, most of the stations in the network exhibited positive trends. Relatively few of these trends were statistically significant. This paper updates our earlier analysis by extending the data sets of the network up to the year 1990. The spatial variations in surface ozone trends over the extended period 1978-1990 are examined and discussed in comparison to the 1978-1988 patterns. The update confirms the overall conclusions of the earlier analysis, specifically that caution should be exercised in interpreting the results of trend analyses based on station data representative of a limited period of time and/or geographical area.

  18. Trends in Philippine Library History.

    ERIC Educational Resources Information Center

    Hernandez, Vicente S.

    This paper divides Philippine library history into three periods, establishing a relationship between historical events and library trends. During the Spanish period, modern library trends were introduced through the establishment of the Sociedad Economica in 1780, but did not influence Philippine library culture until the later part of the 19th…

  19. General Achievement Trends: New Jersey

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  20. Interior Design Trends in Libraries.

    ERIC Educational Resources Information Center

    Sager, Don, Ed.

    2000-01-01

    Four contributing authors discuss perspectives on current trends in library interior design. Articles include: "Trends in Library Furnishings: A Manufacturer's Perspective" (Andrea Johnson); "Libraries, Architecture, and Light: The Architect's Perspective" (Rick McCarthy); "The Library Administrator's Perspective" (Chadwick Raymond); and "The…

  1. Trends in Family Child Care

    ERIC Educational Resources Information Center

    Neugebauer, Roger

    2011-01-01

    The author presents insights from various readers of "ExchangeEveryDay" regarding trends in the world of family child care. Kathleen Reticker of Acre Family Child Care in Lowell, Massachusetts thinks an increasing trend in Family Child Care is the pressure to emulate a Center, instead of seeing family child care as a different model. Over the…

  2. General Achievement Trends: North Carolina

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  3. Trends in Classroom Observation Scores

    ERIC Educational Resources Information Center

    Casabianca, Jodi M.; Lockwood, J. R.; McCaffrey, Daniel F.

    2015-01-01

    Observations and ratings of classroom teaching and interactions collected over time are susceptible to trends in both the quality of instruction and rater behavior. These trends have potential implications for inferences about teaching and for study design. We use scores on the Classroom Assessment Scoring System-Secondary (CLASS-S) protocol from…

  4. Trends in Technology and Employment.

    ERIC Educational Resources Information Center

    Conrath, Nancy L.

    Drawing from literature on technological advances, economic trends, and employment and labor market projections, this paper provides an overview of trends and their implications for California. After briefly analyzing the characteristics and effects of the information age, the paper examines the growth and development of high technology…

  5. HRD Future and Trends. Symposium.

    ERIC Educational Resources Information Center

    2002

    This document contains three papers from a symposium on the future of human resource development (HRD) and trends in HRD. "Searching for the Future of Human Resource Development" (Wendy E.A. Ruona, Susan A. Lynham, Tom Chermack) reports on a survey of 55 HRD and HRD-related practitioners and academics that examined trends in the HRD profession,…

  6. Trends Shaping Education--2008 Edition

    ERIC Educational Resources Information Center

    OECD Publishing (NJ3), 2008

    2008-01-01

    This new biennial publication presents the latest available information on 26 major current trends in education, grouped in 9 broad themes (ageing, global challenges, the new economic landscape, work and jobs, the learning society, ICT, citizenship and the state, social connections and values, and sustainable affluence). For each trend, there is a…

  7. Trends in Global Gender Inequality

    ERIC Educational Resources Information Center

    Dorius, Shawn F.; Firebaugh, Glenn

    2010-01-01

    This study investigates trends in gender inequality throughout the world. Using data encompassing a large majority of the world's population, we examine trends in recent decades for key indicators of gender inequality in education, mortality, political representation and economic activity. We find that gender inequality is declining in virtually…

  8. Projecting Trends in Public Policy.

    ERIC Educational Resources Information Center

    Nagel, Stuart S.

    Looking back over the past 40 years, one can observe at least seven trends in public policy substance and in the study of public policy: (1) There is a trend toward higher goals for society in economic, social, political, and science policy. (2) Major changes in almost all fields of public policy have resulted in increased benefits for the less…

  9. NASA standard: Trend analysis techniques

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Descriptive and analytical techniques for NASA trend analysis applications are presented in this standard. Trend analysis is applicable in all organizational elements of NASA connected with, or supporting, developmental/operational programs. This document should be consulted for any data analysis activity requiring the identification or interpretation of trends. Trend analysis is neither a precise term nor a circumscribed methodology: it generally connotes quantitative analysis of time-series data. For NASA activities, the appropriate and applicable techniques include descriptive and graphical statistics, and the fitting or modeling of data by linear, quadratic, and exponential models. Usually, but not always, the data is time-series in nature. Concepts such as autocorrelation and techniques such as Box-Jenkins time-series analysis would only rarely apply and are not included in this document. The basic ideas needed for qualitative and quantitative assessment of trends along with relevant examples are presented.

  10. Global fertility and population trends.

    PubMed

    Bongaarts, John

    2015-01-01

    Over the past several decades, the world and most countries have undergone unprecedented demographic change. The most obvious example of this change is the rise in human numbers, and there are also important trends in fertility, family structure, mortality, migration, urbanization, and population aging. This paper summarizes past trends and projections in fertility and population. After reaching 2.5 billion in 1950, the world population grew rapidly to 7.2 billion in 2013 and the projections expect this total to be 10.9 billion by 2100. World regions differ widely in their demographic trends, with rapid population growth and high fertility continuing in the poorest countries, particularly in sub-Saharan Africa, while population decline, population aging, and very low fertility are now a key concern in many developed countries. These trends have important implications for human welfare and are of interest to policy makers. The conclusion comments briefly on policy options to address these adverse trends.

  11. Hydroclimatic and water quality trends across three Mediterranean river basins.

    PubMed

    Lutz, Stefanie R; Mallucci, Stefano; Diamantini, Elena; Majone, Bruno; Bellin, Alberto; Merz, Ralf

    2016-11-15

    Water resources are under pressure from multiple anthropogenic stressors such as changing climate, agriculture and water abstraction. This holds, in particular, for the Mediterranean region, where substantial changes in climate are expected throughout the 21st century. Nonetheless, little attention has been paid to linkages between long-term trends in climate, streamflow and water quality in Mediterranean river basins. In the present study, we perform a comparative analysis of recent trends in hydroclimatic parameters and nitrate pollution in three climatologically different Mediterranean watersheds (i.e., the Adige, Ebro and Sava River Basins). Mann-Kendall trend analyses of annual mean temperature, precipitation and streamflow (period 1971 to 2010) and monthly nitrate concentrations, mass fluxes and flow-adjusted concentrations (period 1996 to 2012) were performed in these river basins. Temperature is shown to have increased the most in the Ebro followed by the Sava, whereas minor increases are observed in the Adige. Precipitation presents, overall, a negative trend in the Ebro and a positive trend in both the Adige and Sava. These climatic trends thus suggest the highest risk of increasing water scarcity for the Ebro and the lowest risk for the Adige. This is confirmed by trend analyses of streamflow time series, which indicate a severe decline in streamflow for the Ebro and a substantial decline in the Sava, as opposed to the Adige showing no prevailing trend. Concerning surface water quality, nitrate pollution appears to have decreased in all study basins. Overall, these findings emphasize progressive reduction of water resources availability in river basins characterized by continental climate (i.e., Ebro and Sava). This study thus underlines the need for adapted river management in the Mediterranean region, particularly considering strong feedbacks between hydroclimatic trends, freshwater ecosystem services and water resources availability for agriculture

  12. Antarctic Sea Ice Variability and Trends, 1979-2010

    NASA Technical Reports Server (NTRS)

    Parkinson, C. L.; Cavalieri, D. J.

    2012-01-01

    In sharp contrast to the decreasing sea ice coverage of the Arctic, in the Antarctic the sea ice cover has, on average, expanded since the late 1970s. More specifically, satellite passive-microwave data for the period November 1978 - December 2010 reveal an overall positive trend in ice extents of 17,100 +/- 2,300 square km/yr. Much of the increase, at 13,700 +/- 1,500 square km/yr, has occurred in the region of the Ross Sea, with lesser contributions from the Weddell Sea and Indian Ocean. One region, that of the Bellingshausen/Amundsen Seas, has, like the Arctic, instead experienced significant sea ice decreases, with an overall ice extent trend of -8,200 +/- 1,200 square km/yr. When examined through the annual cycle over the 32-year period 1979-2010, the Southern Hemisphere sea ice cover as a whole experienced positive ice extent trends in every month, ranging in magnitude from a low of 9,100 +/- 6,300 square km/yr in February to a high of 24,700 +/- 10,000 square km/yr in May. The Ross Sea and Indian Ocean also had positive trends in each month, while the Bellingshausen/Amundsen Seas had negative trends in each month, and the Weddell Sea and Western Pacific Ocean had a mixture of positive and negative trends. Comparing ice-area results to ice-extent results, in each case the ice-area trend has the same sign as the ice-extent trend, but differences in the magnitudes of the two trends identify regions with overall increasing ice concentrations and others with overall decreasing ice concentrations. The strong pattern of decreasing ice coverage in the Bellingshausen/Amundsen Seas region and increasing ice coverage in the Ross Sea region is suggestive of changes in atmospheric circulation. This is a key topic for future research.

  13. Environmental trends in extinction during the Paleozoic

    NASA Technical Reports Server (NTRS)

    Sepkoski, J. John, Jr.

    1987-01-01

    Extinction intensities calculated from 505 Paleozoic marine assemblages divided among six environmental zones and 40 stratigraphic intervals indicate that whole communities exhibit increasing extinction offshore but that genera within individual taxonomic classes tend to have their highest extinction onshore. The offshore trend at the community level results from a concentration of genera in classes with low characteristic extinction rates in nearshore environments. This finding is consistent with the ecologic expectation that organisms inhabiting unpredictably fluctuating environments should suffer more extinction than counterparts living under more predictably equitable conditions.

  14. Aging trends -- the Philippines.

    PubMed

    Biddlecom, A E; Domingo, L J

    1996-03-01

    This report presents a description of the trends in growth of the elderly population in the Philippines and their health, disability, education, work status, income, and family support. The proportion of elderly in the Philippines is much smaller than in other Southeast Asian countries, such as Singapore and Malaysia. The elderly population aged over 65 years increased from 2.7% of total population in 1990 to 3.6% in 1990. The elderly are expected to comprise 7.7% of total population in 2025. The proportion of elderly is small due to the high fertility rate. Life expectancy averages 63.5 years. The aged dependency ratio will double from 5.5 elderly per 100 persons aged 15-64 years in 1990 to 10.5/100 in 2025. A 1984 ASEAN survey found that only 11% of elderly rated their health as bad. The 1990 Census reveals that 3.9% were disabled elderly. Most were deaf, blind, or orthopedically impaired. 16% of elderly in the ASEAN survey reported not seeing a doctor even when they needed to. 54% reported that a doctor was not visited due to the great expense. In 1980, 67% of men and 76% of women aged over 60 years had less than a primary education. The proportion with a secondary education in 2020 is expected to be about 33% for men and 33% for women. 66.5% of men and 28.5% of women aged over 60 years were in the formal labor force in 1990. Women were less likely to receive cash income from current jobs or pensions. 65% of earnings from older rural people was income from agricultural production. 60% of income among urban elderly was from children, and 23% was from pensions. Family support is provided to the elderly in the form of coresidence. In 1988, 68% of elderly aged over 60 years lived with at least one child. Retirement or nursing homes are uncommon. The Philippines Constitution states that families have a duty to care for elderly members. PMID:12292274

  15. Aging trends -- the Philippines.

    PubMed

    Biddlecom, A E; Domingo, L J

    1996-03-01

    This report presents a description of the trends in growth of the elderly population in the Philippines and their health, disability, education, work status, income, and family support. The proportion of elderly in the Philippines is much smaller than in other Southeast Asian countries, such as Singapore and Malaysia. The elderly population aged over 65 years increased from 2.7% of total population in 1990 to 3.6% in 1990. The elderly are expected to comprise 7.7% of total population in 2025. The proportion of elderly is small due to the high fertility rate. Life expectancy averages 63.5 years. The aged dependency ratio will double from 5.5 elderly per 100 persons aged 15-64 years in 1990 to 10.5/100 in 2025. A 1984 ASEAN survey found that only 11% of elderly rated their health as bad. The 1990 Census reveals that 3.9% were disabled elderly. Most were deaf, blind, or orthopedically impaired. 16% of elderly in the ASEAN survey reported not seeing a doctor even when they needed to. 54% reported that a doctor was not visited due to the great expense. In 1980, 67% of men and 76% of women aged over 60 years had less than a primary education. The proportion with a secondary education in 2020 is expected to be about 33% for men and 33% for women. 66.5% of men and 28.5% of women aged over 60 years were in the formal labor force in 1990. Women were less likely to receive cash income from current jobs or pensions. 65% of earnings from older rural people was income from agricultural production. 60% of income among urban elderly was from children, and 23% was from pensions. Family support is provided to the elderly in the form of coresidence. In 1988, 68% of elderly aged over 60 years lived with at least one child. Retirement or nursing homes are uncommon. The Philippines Constitution states that families have a duty to care for elderly members.

  16. Developing a Critical View on E-Learning Trend Reports: Trend Watching or Trend Setting?

    ERIC Educational Resources Information Center

    Boon, Jo; Rusman, Ellen; van der Klink, Marcel; Tattersall, Colin

    2005-01-01

    Trend watching reports are an indispensable resource in the e-learning domain. Many HRD departments consider these reports as essential cornerstones for the development of their e-learning strategy. But what is the quality of the forecasts made in these reports? In this article, several methods of forecasting trends are discussed, resulting in a…

  17. New trends in immunoassays.

    PubMed

    Chan, Cangel Pui-yee; Cheung, Yiu-chi; Renneberg, Reinhard; Seydack, Matthias

    2008-01-01

    This article takes a special focus on signal amplification technologies in immunoassays and new generations of lateral-flow assays. Novel signal amplification technologies based either on new classes of biofunctional nanocrystals consisting of releasable fluorophores or on aggregation-induced emission (AIE) can improve the sensitivity and the limits of detection in immunoassays. A bio-barcode assay also allows signal amplification by utilizing antibody-coated magnetic beads to concentrate the analytes and antibody-coated gold nanoparticle probes to carry with a large number of oligonucleotides. These innovative technologies boost the development of immunoassays. Growth in rapid immunoassay is fueled by the increasing number of diabetics, the globalization of infectious diseases and the surge in cardiovascular and other chronic diseases as well as other chronic conditions. Rapid, near patient, decentralized, point-of-care (POC) tests are emerging as a tool for more efficient diagnosis and patient evaluation. Technological innovations in lateral-flow assays have enabled a move to bring testing closer to the patient. A novel "digital-style" lateral-flow assay provides semi-quantitative results by simply counting the number of red lines in the test without any expensive reading instrument. An immuno-threshold-based assay can give a signal directly proportional to the concentration of a hapten to prevent confusion on interpretation of the test results. In addition, POC tests become more meaningful to healthcare professionals by combining the benefits of new technologies to provide quantitative results. A molecular compact disc provides a high-resolution imaging capability that can identify and quantify many different antigens simultaneously in highly complex immunoassays. Further advances in immunoassays will bring diagnostic testing even closer to the patient, and can help physicians to monitor diseases that require immediate test results, thereby enhancing the quality

  18. Filtering ionosphere parameters to detect trends linked to anthropogenic effects

    NASA Astrophysics Data System (ADS)

    Elias, Ana G.

    2014-12-01

    The great concern about the global warming observed in the troposphere has generated a large interest in the study of long-term trends in the ionosphere since the early 1990s, which has now become a significant topic in global change investigations. Some research works link ionosphere trends to anthropogenic sources such as the increase in greenhouse gas concentration, and others to natural causes such as solar and geomagnetic activity long-term changes, and secular variations in the Earth's main magnetic field. In all the cases, in order to analyze ionospheric trends, solar activity effect must be filtered out first since around 90% of ionosphere parameter variance is due to solar variations. The filtering process can generate `spurious' trends in the filtered data series which may lead to erroneous conclusions. foF2 data series which include solar cycle 23 are analyzed in the present work in order to detect the effect of different filtering procedures on the determination of long-term trends. In particular, solar cycle 23 seems to have had an extreme ultraviolet (EUV) emission greater than that deduced from traditional solar EUV proxies during the maximum epoch and lower during the minimum epoch. When solar activity is filtered assessing the residuals of a linear regression between foF2 and Rz, or between foF2 and F10.7, this fact may bias trend values especially because it is at the end of the time series. The length of the period considered for trend assessment, the saturation and hysteresis effect of some ionosphere parameters, and the solar EUV proxy used are also considered in this study in order to quantify a possible spurious trend that may result as a by-product of a filtering process. Since trends expected as a consequence of anthropogenic effects are relatively small, these spurious effects may surely mask, or enhance, trends expected from anthropogenic origins.

  19. Monitoring grizzly bear population trends

    USGS Publications Warehouse

    Eberhardt, L.L.; Knight, R.R.; Blanchard, B.M.

    1986-01-01

    A simple different equation model was developed to provide additional perspective on observed mortality and trend data on Yellowstone grizzly bears (Ursus arctos horribilis). Records of mortalities of adult females from 1959 to 1985 were utilized, in conjunction with data on females with cubs. The overall downward trend of observed numbers of females with cubs generally agrees with the model calculations but does not adequately reflect mortality from 1970 to 1974. The model may be useful in developing a composite index of population trend.

  20. Trends Online: A Compendium of Data on Global Change

    DOE Data Explorer

    Trends Online provides synopses of frequently used time series of global-change data: • historical and modern records (from ice cores and current monitoring stations) of atmospheric concentrations of carbon dioxide (CO2) • atmospheric concentrations of methane • isotopic measurements (14C et al.) for atmospheric greenhouse gases • estimates of global, regional, and national CO2 emissions from the combustion of fossil fuels, gas flaring, and the production of cement • global emissions estimates for methane (CH4) • carbon flux from land-cover change • long-term temperature records, whose spatial coverage ranges from individual sites to the entire globe and from the Earth's surface to the lower stratosphere • total cloud amount over China • ecosystems (area and carbon content) Data records are presented in multipage formats, each dealing with a specific site, region, or emissions species. The data records include tables; graphs; discussions of methods for collecting, measuring, and reporting the data; trends in the data, and references to literature providing further information. Instructions for citing specific data in Trends Online are provided for each compiled data set. All data appearing in Trends Online are available, on request, on digital media from CDIAC at no cost. [Copied from the Abstract to Trends Online at http://cdiac.ornl.gov/trends/abstract.htm

  1. Global Trends of Tropospheric NO2 Observed From Space

    NASA Astrophysics Data System (ADS)

    Schneider, P.; van der A, R. J.

    2012-04-01

    Nitrogen Dioxide (NO2) is one of the major atmospheric pollutants and is primarily emitted by industrial activity and transport. While observations of NO2 are frequently being carried out at air quality stations, such measurements are not able to provide a global perspective of spatial patterns in NO2 concentrations and their associated trends due to the stations' limited spatial representativity and an extremely sparse and often completely non-existent station coverage in developing countries. Satellite observations of tropospheric NO2 are able to overcome this issue and provide an unprecedented global view of spatial patterns in NO2 levels and due to their homogeneity are well suited for studying trends. Here we present results of a global trend analysis from nearly a decade of NO2 observations made by the SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CartograpHY) instrument onboard the Envisat satellite platform. Using only SCIAMACHY data allows for mapping global and regional trends at an unprecedented spatial resolution since no aggregation to the coarser resolution of other sensors is necessary. Monthly average tropospheric NO2 column data was acquired for the period between August 2002 and August 2011. A trend analysis