| Abstract: | The Mississippi River and its major tributaries transport herbicides and their degradation products from agricultural areas in the mid-western U.S.A. These compounds include atrazine and its degradation products (desethyl- and desisopropylatrazine), simazine, cyanazine, metolachlor, and alachlor and its degradation products (2-chloro-2‘,6‘-diethylacetanilide, 2-hydroxy-2‘,6‘-diethylacetanilide and 2,6-diethylaniline). These compounds were identified and confirmed by gas chromatography-ion trap mass spectrometry. Loads of these compounds were determined during five sampling trips in 1987-1989. Stream loads of these compounds indicated that atrazine and metolachlor were relatively conservative in downstream transport. Alachlor and its degradation products were generated from point and non-point sources. Seasonal variations and hydrologic conditions controlled the loads of these compounds in the Mississippi River. Cross-channel mixing was slow downstream from major river confluences, possibly requiring several hundred kilometers of downriver transit for completion. The annual transport of these compounds into the Gulf of Mexico was estimated to be < 2% of the annual application of each herbicide in the Midwest.The Mississippi River and its major tributaries transport herbicides and their degradation products from agricultural areas in the mid-western U.S.A. These compounds include atrazine and its degradation products (desethyl- and desisopropylatrazine), simazine, cyanazine, metolachlor, and alachlor and its degradation products (2-chloro-2???,6???-diethylacetanilide, 2-hydroxy-2???,6???-diethylacetanilide and 2,6-diethylaniline). These compounds were identified and confirmed by gas chromatography-ion trap mass spectrometry. Loads of these compounds were determined during five sampling trips in 1987-1989. Stream loads of these compounds indicated that atrazine and metolachlor were relatively conservative in downstream transport. Alachlor and its degradation products were generated from point and non-point sources. Seasonal variations and hydrologic conditions controlled the loads of these compounds in the Mississippi River. Cross-channel mixing was slow downstream from major river confluences, possibly requiring several hundred kilometers of downriver transit for completion. The annual transport of these compounds into the Gulf of Mexico was estimated to be <2% of the annual application of each herbicide in the Midwest. |
| Genre: | Conference Paper |
| ProdID: | 70017214 |
| Citation Author: | Pereira, W. E.; Rostad, C. E.; Leiker, T. J. |
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| Citation Editor: | McCalady Donald L. |
| Citation End Page: | 188 |
| Citation Issue: | 1-2 |
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| Citation Language: | English |
| Citation Larger Work Title: | Journal of Contaminant Hydrology |
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| Citation Number Of Pages: | 14 |
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| Citation Search Results Text: | Synthetic organic agrochemicals in the lower Mississippi River and its major tributaries: Distribution, transport and fate; 1992; Conference Paper; Journal of Contaminant Hydrology; Pereira, W. E.; Rostad, C. E.; Leiker, T. J. |
| Citation Start Page: | 175 |
| Citation Volume: | 9 |
| Citation Year: | 1992 |
| Type: | citation/reference |
| Text: | Synthetic organic agrochemicals in the lower Mississippi River and its major tributaries: Distribution, transport and fate; 1992; Conference Paper; Journal of Contaminant Hydrology; Pereira, W. E.; Rostad, C. E.; Leiker, T. J. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Wed, 1 Jan 1992 00:00 -0600 |
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