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Jo Ann M Gronberg

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There are two datasets in the compressed file along with individual metadata files which completely describe the datasets. The first data set consists of county estimates of nitrogen and phosphorus in kilograms from animal manure for the conterminous United States for 2007 and 2012. These data are available as both text files and spreadsheets. These estimates were based on county-level population data of livestock, poultry, and other animals (cattle, poultry, hogs and pigs, horses and ponies, sheep and lambs) from the 2007 and 2012 Census of Agriculture, using methods described in U.S. Geological Survey Scientific Investigations Report 2006-5012. The second dataset is a 30 by 30 meter (m) resolution grid of counties...
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The ascii grids represent regional probabilities that groundwater in a particular location will have dissolved oxygen (DO) concentrations less than selected threshold values representing anoxic groundwater conditions or will have dissolved manganese (Mn) concentrations greater than selected threshold values representing secondary drinking water-quality contaminant levels (SMCL) and health-based screening levels (HBSL) for water quality. The probability models were constrained by the alluvial boundary of the Central Valley to a depth of approximately 300 meters (m). We utilized prediction modeling methods, specifically boosted regression trees (BRT) with a Bernoulli error distribution within a statistical learning...
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