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Distribution of agrochemicals in the lower Mississippi River and its tributaries

January 1, 1990

The Mississippi River and its tributaries drain extensive agricultural regions of the Mid-Continental United States. Millions of pounds of herbicides are applied annually in these areas to improve crop yields. Many of these compounds are transported into the river from point and nonpoint sources, and eventually are discharged into the Gulf of Mexico. Studies being conducted by the U.S. Geological Survey along the lower Mississippi River and its major tributaries, representing a 2000 km river reach, have confirmed that several triazine and acetanilide herbicides and their degradation products are ubiquitous in this riverine system. These compounds include atrazine and its degradation products desethyl and desisopropylatrazine, cyanazine, simazine, metolachlor, and alachlor and its degradation products 2-chloro-2',6'-diethylacetanilide, 2-hydroxy-2',6-diethylacetanilide and 2,6-diethylaniline. Loads of these compounds were determined at 16 different sampling stations. Stream-load calculations provided information concerning (a) conservative or nonconservative behavior of herbicides; (b) point sources or nonpoint sources; (c) validation of sampling techniques; and (d) transport past each sampling station.

Publication Year 1990
Title Distribution of agrochemicals in the lower Mississippi River and its tributaries
DOI 10.1016/0048-9697(90)90229-N
Authors W. E. Pereira, C.E. Rostad, T.J. Leiker
Publication Type Article
Publication Subtype Journal Article
Series Title Science of Total Environment
Index ID 70015942
Record Source USGS Publications Warehouse
USGS Organization Toxic Substances Hydrology Program