thumbnail

Aqueous-phase disappearance of atrazine, metolachlor, and chlorpyrifos in laboratory aquaria and outdoor macrocosms

Archives of Environmental Contamination and Toxicology

5981 Mazanti.pdf
By:
, , , , , , , and

Links

Abstract

Dissipation processes are described for a combination of commonly used pesticides--atrazine (6-chloro-4--ethylamino-6-isopropylamino-s-triazine), metolachlor (2-chloro-N-[2-ethyl-6-methyl-phenyl]-N-[2-methoxy-l-methylethyl] acetamide), and chlorpyrifos (O-O diethyl O-[3,5,6-trichloro-2-pyridinyl] phosphorothioate)--in a laboratory and outdoor pond systems. Dosing rates and timing were designed to duplicate those common in the mid-Atlantic Coastal Plain, USA. Treatment ranged from 2 and 2.5 mg/L to 0.2 and 0.25 mg/L respectively for atrazine and metolachlor, and chlorpyrifos was added at 1.0 and 0.1 mg/L in the aquaria and at 0.1 mg/L in the outdoor macrocosms. Chlorpyrifos disappearance was rapid in all of the systems and followed a two-phase sequence. Initial half-lives varied from 0.16 da), to 0.38 day and showed similar rates in the aquaria and the outdoor systems. The second phase of the chlorpyrifos loss pattern was slower (18-20 days) in all the treatments except for the low herbicide treatment in the outdoor test, where it was 3.4 days. Compared to the outdoor system, herbicide losses were much slower in the aquaria, e.g., 150 days for atrazine and 55 days for metolachlor, and no appreciable loss of herbicide was apparent in the high-treated aquaria. In the outdoor systems, the half-lives for the low herbicide treatment were 27 days and 12 days, respectively, for atrazine and metolachlor, and 48 and 20 days, respectively for the high herbicide-treated pond. Very low levels of CIAT (6-amino-2-chloro-4-iso-propylamino-s-triazine) and CEAT (2-chloro-4-ethylamino-6-ethylamino-s-triazine), degradation products of atrazine, were observed in the outdoor studies.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Aqueous-phase disappearance of atrazine, metolachlor, and chlorpyrifos in laboratory aquaria and outdoor macrocosms
Series title:
Archives of Environmental Contamination and Toxicology
Volume
44
Issue:
1
Year Published:
2003
Language:
English
Contributing office(s):
Patuxent Wildlife Research Center
Description:
67-76
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Archives of Environmental Contamination and Toxicology
First page:
67
Last page:
76