Institution
United States Environmental Protection Agency
Government•Washington D.C., District of Columbia, United States•
About: United States Environmental Protection Agency is a government organization based out in Washington D.C., District of Columbia, United States. It is known for research contribution in the topics: Population & Environmental exposure. The organization has 13873 authors who have published 26902 publications receiving 1191729 citations. The organization is also known as: EPA & Environmental Protection Agency.
Papers published on a yearly basis
Papers
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TL;DR: Results indicate that the ability of populations to adapt depends on the presence of specific microorganisms, and adaptation must be considered when such systems are used to predict the fate of xenobiotics in the environment.
Abstract: Experiments were devised to determine whether exposure to xenobiotics would cause microbial populations to degrade the compounds more rapidly during subsequent exposures. Studies were done with water/sediment systems (ecocores) taken from a salt marsh and a river. Systems were tested for adaptation to the model compounds methyl parathion and p-nitrophenol. CO(2) released from radioactive parent compounds was used as a measure of mineralization. River populations preexposed to p-nitrophenol at concentrations as low as 60 mug/liter degraded the nitrophenol much faster than did control populations. River populations preexposed to methyl parathion also adapted to degrade the pesticide more rapidly, but higher concentrations were required. Salt marsh populations did not adapt to degrade methyl parathion. p-Nitrophenol-degrading bacteria were isolated from river samples but not from salt marsh samples. Numbers of nitrophenol-degrading bacteria increased 4 to 5 orders of magnitude during adaptation. Results indicate that the ability of populations to adapt depends on the presence of specific microorganisms. Biodegradation rates in laboratory systems can be affected by concentration and prior exposure; therefore, adaptation must be considered when such systems are used to predict the fate of xenobiotics in the environment.
250 citations
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TL;DR: This article used the US Geological Survey (USGS) 1° digital elevation series and National Oceanic and Atmospheric Administration (NOAA) shoreline data to illustrate the land below the 1.5 and 3.5 m contours for areas the size of entire US states or larger.
Abstract: Understanding the broad-scale ramifications of accelerated sea level rise requires maps of the land that could be inundated or eroded. Producing such maps requires a combination of ele- vation information and models of shoreline erosion, wetland accretion, and other coastal processes. Assessments of coastal areas in the United States that combine all of these factors have focused on relatively small areas, usually 25 to 30 km wide. In many cases, the results are as sensitive to uncer- tainty regarding geological processes as to the rate of sea level rise. This paper presents maps illus- trating the elevations of lands close to sea level. Although elevation contours do not necessarily coin- cide with future shorelines, the former is more transparent and less dependent on subjective modeling. Several methods are available for inferring elevations given limited data. This paper uses the US Geological Survey (USGS) 1° digital elevation series and National Oceanic and Atmospheric Administration (NOAA) shoreline data to illustrate the land below the 1.5 and 3.5 m contours for areas the size of entire US states or larger. The maps imply that approximately 58 000 km 2 of land along the Atlantic and Gulf coasts lie below the 1.5 m contour. Louisiana, Florida, Texas, and North Carolina account for more than 80% of the low land. Outside of those 4 states, the largest vulnerable populated region is the land along the Eastern Shore of Chesapeake Bay stretching from Dorchester County, Maryland, to Accomac County, Virginia.
249 citations
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TL;DR: The model described here is the first environmentally extended MRIO model that harmonizes EF and WF accounts and aligns physical unit data of product use with standard economic and environmental accounting, and provides a structure upon which further improvements in footprint calculation can be built.
249 citations
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TL;DR: The current work describes the evolution of the unique team-based governmental response to the perchlorate contamination problem and the rapidity of its development.
249 citations
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TL;DR: In this article, the influence of variable light and temperature on isoprene emissions from live oak (Quercus virginiana mill) was assessed, showing that higher temperatures caused a large decrease in emissions.
Abstract: There is a growing awareness of the role of vegetation as a source of reactive hydrocarbons that may serve as photochemical oxidant precursors. A study was designed to assess independently the influence of variable light and temperature on isoprene emissions from live oak (Quercus virginiana Mill.). Plants were conditioned in a growth chamber and then transferred to an environmentally controlled gas-exchange chamber. Samples of the chamber atmosphere were collected; isoprene was concentrated cryogenically and measured by gas chromatography. A logistic function was used to model isoprene emission rates. Under regimes of low temperature (20°C) or darkness, isoprene emissions were lowest. With increasing temperature or light intensity, the rate of isoprene emission increased, reaching maxima at 800 μE m-2 s-1 and 40–44°C, respectively. Higher temperatures caused a large decrease in emissions. Since the emissions of isoprene were light-saturated at moderate intensities, temperature appeared to be the main factor controlling emissions during most of the day. Carbon lost through isoprene emissions accounted for 0.1 to 2% of the carbon fixed during photosynthesis depending on light intensity and temperature.
249 citations
Authors
Showing all 13926 results
Name | H-index | Papers | Citations |
---|---|---|---|
Joel Schwartz | 183 | 1149 | 109985 |
Timothy A. Springer | 167 | 669 | 122421 |
Chien-Jen Chen | 128 | 655 | 66360 |
Matthew W. Gillman | 126 | 529 | 55835 |
J. D. Hansen | 122 | 975 | 76198 |
Dionysios D. Dionysiou | 116 | 675 | 48449 |
John P. Giesy | 114 | 1162 | 62790 |
Douglas W. Dockery | 105 | 244 | 57461 |
Charles P. Gerba | 102 | 692 | 35871 |
David A. Savitz | 99 | 572 | 32947 |
Stephen Polasky | 99 | 354 | 59148 |
Judith C. Chow | 96 | 427 | 32632 |
Diane R. Gold | 95 | 443 | 30717 |
Scott L. Zeger | 95 | 377 | 78179 |
Rajender S. Varma | 95 | 672 | 37083 |