Scientific Investigations Report 2012–5241
Anthropogenic inputs of nitrogen and phosphorus to each county in the conterminous United States and to the watersheds of 495 surface-water sites studied as part of the U.S. Geological Survey National Water-Quality Assessment Program were quantified for the years 1992, 1997, and 2002. Estimates of inputs of nitrogen and phosphorus from biological fixation by crops (for nitrogen only), human consumption, crop production for human consumption, animal production for human consumption, animal consumption, and crop production for animal consumption for each county are provided in a tabular dataset. These county-level estimates were allocated to the watersheds of the surface-water sites to estimate watershed-level inputs from the same sources; these estimates also are provided in a tabular dataset, together with calculated estimates of net import of food and net import of feed and previously published estimates of inputs from atmospheric deposition, fertilizer, and recoverable manure. The previously published inputs are provided for each watershed so that final estimates of total anthropogenic nutrient inputs could be calculated. Estimates of total anthropogenic inputs are presented together with previously published estimates of riverine loads of total nitrogen and total phosphorus for reference.
First posted January 16, 2013
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Sprague, L.A., and Gronberg, J.M., 2013, Estimated anthropogenic nitrogen and phosphorus inputs to the land surface of the conterminous United States—1992, 1997, and 2002: U.S. Geological Survey Scientific Investigations Report 2012–5241, 14 p.
Estimation of Anthropogenic Nutrient Inputs
Determination of Individual Nutrient Inputs to the Watersheds of NAWQA Surface-Water Sites
Total Anthropogenic Nutrient Inputs to Watersheds
Description of the County-Level Nutrient-Input Dataset
Description of the Watershed-Level Nutrient-Input Dataset