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Regional effects of agricultural conservation practices on nutrient transport in the Upper Mississippi River Basin

Environmental Science & Technology

By:
, ORCID iD , , , , ORCID iD , and
https://doi.org/10.1021/acs.est.5b03543

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Abstract

Despite progress in the implementation of conservation practices, related improvements in water quality have been challenging to measure in larger river systems. In this paper we quantify these downstream effects by applying the empirical U.S. Geological Survey water-quality model SPARROW to investigate whether spatial differences in conservation intensity were statistically correlated with variations in nutrient loads. In contrast to other forms of water quality data analysis, the application of SPARROW controls for confounding factors such as hydrologic variability, multiple sources and environmental processes. A measure of conservation intensity was derived from the USDA-CEAP regional assessment of the Upper Mississippi River and used as an explanatory variable in a model of the Upper Midwest. The spatial pattern of conservation intensity was negatively correlated (p = 0.003) with the total nitrogen loads in streams in the basin. Total phosphorus loads were weakly negatively correlated with conservation (p = 0.25). Regional nitrogen reductions were estimated to range from 5 to 34% and phosphorus reductions from 1 to 10% in major river basins of the Upper Mississippi region. The statistical associations between conservation and nutrient loads are consistent with hydrological and biogeochemical processes such as denitrification. The results provide empirical evidence at the regional scale that conservation practices have had a larger statistically detectable effect on nitrogen than on phosphorus loadings in streams and rivers of the Upper Mississippi Basin.

Additional publication details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Regional effects of agricultural conservation practices on nutrient transport in the Upper Mississippi River Basin
Series title:
Environmental Science & Technology
DOI:
10.1021/acs.est.5b03543
Volume:
50
Issue:
13
Year Published:
2016
Language:
English
Publisher:
American Chemical Society
Contributing office(s):
South Atlantic Water Science Center
Description:
10 p.
First page:
6991
Last page:
7000
Online Only (Y/N):
N
Additional Online Files (Y/N):
N