Regional and temporal differences in nitrate trends discerned from long-term water quality monitoring data

Journal of the American Water Resources Association
By: , and 

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Abstract

Riverine nitrate (NO3) is a well-documented driver of eutrophication and hypoxia in coastal areas. The development of the elevated river NO3 concentration is linked to anthropogenic inputs from municipal, agricultural, and atmospheric sources. The intensity of these sources has varied regionally, through time, and in response to multiple causes such as economic drivers and policy responses. This study uses long-term water quality, land use, and other ancillary data to further describe the evolution of river NO3 concentrations at 22 monitoring stations in the United States (U.S.). The stations were selected for long-term data availability and to represent a range of climate and land-use conditions. We examined NO3 at the monitoring stations, using a flow-weighting scheme meant to account for interannual flow variability allowing greater focus on river chemical conditions. River NO3 concentration increased strongly during 1945-1980 at most of the stations and have remained elevated, but stopped increasing during 1981-2008. NO3 increased to a greater extent at monitoring stations in the Midwest U.S. and less so at those in the Eastern and Western U.S. We discuss 20th Century agricultural development in the U.S. and demonstrate that regional differences in NO3 concentration patterns were strongly related to an agricultural index developed using principal components analysis. This unique century-scale dataset adds to our understanding of long-term NO3 patterns in the U.S.

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Publication type Article
Publication Subtype Journal Article
Title Regional and temporal differences in nitrate trends discerned from long-term water quality monitoring data
Series title Journal of the American Water Resources Association
DOI 10.1111/1752-1688.12321
Volume 51
Issue 5
Year Published 2015
Language English
Publisher Wiley
Contributing office(s) National Research Program - Central Branch
Description 14 p.
First page 1394
Last page 1407
Country United States
Online Only (Y/N) N
Additional Online Files (Y/N) N
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