Journal ArticleDOI
Water-Quality Trends in the Nation's Rivers
TLDR
Water-quality records from two nationwide sampling networks now permit nationally consistent analysis of long-term water-quality trends at more than 300 locations on major U.S. rivers, providing new insight into changes in stream quality during a time of major changes in both terrestrial and atmospheric influences on surface waters.Abstract:
Water-quality records from two nationwide sampling networks now permit nationally consistent analysis of long-term water-quality trends at more than 300 locations on major U.S. rivers. Observed trends in 24 measures of water quality for the period from 1974 to 1981 provide new insight into changes in stream quality that occurred during a time of major changes in both terrestrial and atmospheric influences on surface waters. Particularly noteworthy are widespread decreases in fecal bacteria and lead concentrations and widespread increases in nitrate, chloride, arsenic, and cadmium concentrations. Recorded increases in municipal waste treatment, use of salt on highways, and nitrogen fertilizer application, along with decreases in leaded gasoline consumption and regionally variable trends in coal production and combustion during the period appear to be reflected in water-quality changes.read more
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Eutrophication: impacts of excess nutrient inputs on freshwater, marine, and terrestrial ecosystems
TL;DR: Two brief case studies demonstrate that nutrient loading restriction is the essential cornerstone of aquatic eutrophication control, and results of a preliminary statistical analysis are presented consistent with the hypothesis that anthropogenic emissions of oxidized nitrogen could be influencing atmospheric levels of carbon dioxide via nitrogen stimulation of global primary production.
Journal ArticleDOI
Eutrophication of U.S. freshwaters: analysis of potential economic damages.
Walter K. Dodds,Wesley W. Bouska,Jeffrey L. Eitzmann,Tyler J. Pilger,Kristen L. Pitts,Alyssa J. Riley,Joshua Schloesser,Darren J. Thornbrugh +7 more
TL;DR: In this article, the authors compared current total nitrogen (TN) and phosphorus (TP) concentrations for the U.S. Environmental Protection Agency nutrient ecoregions with estimated reference conditions.
Journal ArticleDOI
Arsenic in Ground Water of the United States: Occurrence and Geochemistry
TL;DR: Arsenic release from iron oxide appears to be the most common cause of widespread arsenic concentrations exceeding 10 μg/L in ground water This can occur in response to different geochemical conditions, including release of arsenic to ground water through reaction of iron oxide with either natural or anthropogenic (i, petroleum products) organic carbon Iron oxide also can release arsenic to alkaline ground water, such as that found in some felsic volcanic rocks and alkaline aquifers of the western United States.
Journal ArticleDOI
Distribution of oxygen-18 and deuterium in river waters across the United States†
Carol Kendall,Tyler B. Coplen +1 more
TL;DR: In this article, more than 4800, depth-and width-integrated, stream samples from 391 selected sites within the USGS National Stream Quality Accounting Network (NASQAN) and Hydrologic Benchmark Network (HBN) were analyzed for δ18O and δ2H (http://water.usgs.gov/pubs/ofr/Ofr/of r00-160/pdf/Of r00 -160.pdf).
Journal ArticleDOI
Eutrophication of freshwater and marine ecosystems
TL;DR: This special issue was stimulated by a symposium that culminated in the publication of the first special issue of Limnology and Oceanography on nutrients and eutrophication, edited by G. Likens (Likens 1972a).
References
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Journal ArticleDOI
Techniques of trend analysis for monthly water quality data
TL;DR: The seasonal Kendall test as discussed by the authors is a nonparametric test for trend applicable to data sets with seasonality, missing values, or values reported as "less than" or values below the limit of detection.
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Trace metals in atmospheric deposition: A review and assessment
TL;DR: In this article, information on nineteen metals in atmospheric deposition potentially toxic to humans and other organisms was evaluated to conclude if metal concentrations are increasing in atmospheric deblurring and if these concentrations threaten human or organism health.
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A Decline in Lead Transport by the Mississippi River
TL;DR: Inputs of pollutant lead to the Gulf of Mexico from the Mississippi River have declined by about 40 percent within the past decade, consistent with reduced consumption of lead in gasoline in the United States.
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Exact conditional tests for cross-classifications: Approximation of attained significance levels
TL;DR: In this article, a sampling from the null distribution of tables having the same marginal frequencies as the observed table is used for approximating attained significance levels of exact conditional tests, which yields precise approximations for practically any table dimensions and sample size.