ORCID Profile
0000-0002-9239-4566
Current Organisation
US Geological Survey
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Publisher: Wiley
Date: 14-09-0014
Publisher: Wiley
Date: 25-03-2009
Publisher: US Geological Survey
Date: 2019
DOI: 10.3133/SIR20195069
Publisher: Wiley
Date: 16-01-2014
DOI: 10.1111/JAWR.12153
Publisher: American Chemical Society (ACS)
Date: 21-06-2016
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.
Location: United States of America
No related grants have been discovered for Gregory Schwarz.