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Logistic Model of Nitrate in Streams of the Upper‐Midwestern United States
Author(s) -
Mueller David K.,
Ruddy Barbara C.,
Battaglin William A.
Publication year - 1997
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1997.00472425002600050005x
Subject(s) - nitrate , environmental science , streams , hydrology (agriculture) , maximum contaminant level , soil water , population , water quality , streamflow , zoology , drainage basin , ecology , geography , soil science , biology , computer network , geotechnical engineering , demography , cartography , sociology , computer science , engineering
Nitrate in surface water can have adverse effects on aquatic life and, in drinking‐water supplies, can be a risk to human health. As part of a regional study, nitrate as N (NO 3 ‐N) was analyzed in water samples collected from streams throughout 10 Midwestern states during synoptic surveys in 1989, 1990, and 1994. Data from the period immediately following crop planting at 124 sites were analyzed using logistic regression to relate discrete categories of NO 3 ‐N concentrations to characteristics of the basins upstream from the sites. The NO 3 ‐N data were divided into three categories representing probable background concentrations (<3 mg L −1 ), elevated concentrations (3–10 mg L −1 ), and concentrations that exceeded the U.S. Environmental Protection Agency maximum contaminant level (MCL) for drinking water (>10 mg L −1 ). Nitrate‐N concentrations were positively correlated to streamflow, upstream area planted in corn ( Zea mays L.), and upstream N‐fertilizer application rates. Elevated NO 3 ‐N concentrations were associated with poorly drained soils and were weakly correlated with population density. Nitrate‐N and streamflow data collected during 1989 and 1990 were used to calibrate the model, and data collected during 1994 were used for verification. The model correctly estimated NO 3 ‐N concentration categories for 79% of the samples in the calibration data set and 60% of the samples in the verification data set. The model was used to indicate where NO 3 ‐N concentrations might be elevated or exceed the NO 3 ‐N MCL in streams throughout the study area. The potential for elevated NO 3 ‐N concentrations was predicted to be greatest for streams in Illinois, Indiana, Iowa, and western Ohio.