Triazine herbicides in the hydrologic cycle in the Mississippi River basin
- US Geological Survey, Denver, CO (United States)
Triazine herbicides and their metabolites are present in all compartments of the hydrologic cycle in the Mississippi River basin. In unregulated streams, the occurrence of these chemicals is highly seasonal. Concentrations and mass transport increase abruptly during rainstorms in mid-to-late spring following application and concentrations may briefly exceed 50 micrograms per liter in small to medium sized streams. High concentrations may persist during storm events for several months but generally decrease to trace levels by late summer. In contrast, reservoirs with long hydraulic residence times can collect and store the spring flush of herbicide-laden water. As a result moderate concentrations of herbicides can persist year-round In these reservoirs and in streams that receive the outflow. Rainwater in the Midwest can contain 1 to 3 micrograms per liter of atrazine and smaller amounts of cyanazine and triazine metabolites during May and June, but concentrations decrease to low or undetectable levels by late summer. The seasonal pattern in rainwater is similar to that of streams. Triazine herbicides and metabolites also occur in ground water, but detections are less frequent and concentrations are lower than in surface water. Concentrations rarely exceed health limits when wells are properly constructed. Little or no seasonal variation occurs in ground water.
- OSTI ID:
- 369972
- Report Number(s):
- CONF-960376-; TRN: 96:003805-0019
- Resource Relation:
- Conference: Spring national meeting of the American Chemical Society (ACS), New Orleans, LA (United States), 24-28 Mar 1996; Other Information: PBD: 1996; Related Information: Is Part Of 211th ACS national meeting; PB: 2284 p.
- Country of Publication:
- United States
- Language:
- English
Similar Records
Use of enzyme immunoassay for large water-quality surveys of major herbicides
Atmospheric transport and deposition, an additional input pathway for triazine herbicides to surface waters