HR: 0800h
AN: B41B-0463    [Abstracts]
TI: Assessing the Effects of Corn-Based Ethanol Production on Stream Water Quality
AU: * Alexander, R B
EM: ralex@usgs.gov
AF: U.S. Geological Survey, 12201 Sunrise Valley Drive 413 National Center, Reston, VA 20192, United States
AU: Smith, R A
EM: rsmith1@usgs.gov
AF: U.S. Geological Survey, 12201 Sunrise Valley Drive 413 National Center, Reston, VA 20192, United States
AU: Schwarz, G E
EM: gschwarz@usgs.gov
AF: U.S. Geological Survey, 12201 Sunrise Valley Drive 413 National Center, Reston, VA 20192, United States
AB: Corn grain-based ethanol production nearly doubled over the past five years in response to energy security concerns and the use of ethanol as a gasoline additive. Corn prices show similar increases with much of the rise occurring in more recent years. Farmers responded by planting 93 million acres of corn in 2007, a 19 percent increase over 2006, with most of the new acreage converted from lands in soybeans and cotton. The projected doubling of corn-based ethanol production by 2016 is expected to exert a continued demand for increased corn acreage and production. Both the recent and projected increases in corn production have raised concerns about the degradation of stream water quality; these include the water-quality effects of possible conversions of Conservation Reserve Program lands of which 16 million enrolled acres are slated to expire in 2007. However, no studies of the potential water-quality impacts have been conducted to date. Corn-based agriculture is currently recognized as a major source of nitrogen to Midwestern streams and the northern Gulf of Mexico where increased nitrogen has contributed to coastal eutrophication over the last several decades. Phosphorus from agricultural sources, including corn-based crops, is also known to impair the quality of inland streams and rivers. We use the spatially explicit water-quality model SPARROW (Spatially Referenced Regression on Watershed Attributes) to simulate the potential effects of recent and projected ethanol-related corn production on stream nutrient loads and coastal nutrient delivery. We simulate mean-annual total nitrogen and phosphorus loads in major streams of the conterminous United States, based on the use of a previously estimated national model. The model accounts for major sources and inputs of nutrients to watersheds (e.g., agricultural, atmospheric deposition, human wastes); these are mediated in the model by the effects of climate, topography, soils, and aquatic attenuation processes on transport. In the model simulations, we use county data on the annual corn production and acreage, and facility information on ethanol production to estimate ethanol- related changes in nutrient loads from 2002 to 2007. The simulated changes in stream nutrient loads from 2007 to 2016 are based on several scenarios developed from available information that describes projected changes in corn prices and the associated changes in corn acreage and production required to satisfy increased ethanol production. We summarize the magnitude and geography of the simulated changes in stream nutrients and coastal deliveries from 2002 to 2016, with attention to evaluating the changes in nitrogen and phosphorus concentrations in streams in relation to current nutrient criteria.
DE: 1803 Anthropogenic effects (4802, 4902)
DE: 1847 Modeling
DE: 1871 Surface water quality
SC: Biogeosciences [B]
MN: 2007 Fall Meeting