thumbnail

Occurrence, distributions, and transport of herbicides and their degradation products in the lower Mississippi river and its tributaries

ES and T Contents

By:

Links

  • The Publications Warehouse does not have links to digital versions of this publication at this time

Abstract

The Mississippi River and its tributaries drain extensive agricultural regions of the midcontinental United States, where large amounts of herbicides are applied as weed control agents on crops such as corn and soybeans. Studies being conducted by the U.S. Geological Survey along the lower Mississippi River and its major tributaries, representing a 1930-km river reach, have confirmed that several triazine and chloroacetanilide herbicides and their degradation products are present in this riverine system. These herbicides include atrazine, and its degradation products, desethyl- and desisopropylatrazine; cyanazine; simazine; metolachlor; and alachlor and its degradation products, 2-chloro-2???,6???-diethylacetanilide, and 2-hydroxy-2???,6???-diethylacetanilide. Loads of these compounds were determined at 17 different sampling stations under various seasonal and hydrologic conditions, during five sampling trips from July 1987 to June 1989. Stream loads of herbicides were relatively small during the drought of 1987 and 1988. Stream loads were much greater during the relatively wet year of 1989. Trace levels of atrazine, cyanazine, and metolachlor also were associated with suspended sediments. Distribution coefficients (Koc) of these compounds varied considerably between sites and were much larger than Koc values reported in the literature. The annual transport of atrazine into the Gulf of Mexico was estimated to be less than 2% of the amount of atrazine applied each year in the midwest.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Occurrence, distributions, and transport of herbicides and their degradation products in the lower Mississippi river and its tributaries
Series title:
ES and T Contents
Volume
24
Issue:
9
Year Published:
1990
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
ES and T Contents
First page:
1400
Last page:
1406
Number of Pages:
7