Biotransformation of chlorpyrifos in riparian wetlands in agricultural watersheds: Implications for wetland management


Karpuzcu M. E. , SEDLAK D. L. , Stringfellow W. T.

JOURNAL OF HAZARDOUS MATERIALS, vol.244, pp.111-120, 2013 (Peer-Reviewed Journal) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 244
  • Publication Date: 2013
  • Doi Number: 10.1016/j.jhazmat.2012.11.047
  • Journal Name: JOURNAL OF HAZARDOUS MATERIALS
  • Journal Indexes: Science Citation Index Expanded, Scopus
  • Page Numbers: pp.111-120
  • Keywords: Chlorpyrifos, Organophosphate insecticides, Wetlands, Agricultural drainage, Biodegradation, MICROBIAL-DEGRADATION, CONSTRUCTED WETLANDS, DEGRADING BACTERIUM, LOURENS RIVER, ORGANOPHOSPHORUS COMPOUNDS, PSEUDOMONAS-DIMINUTA, HYDROLYSIS PRODUCT, DRAINAGE DITCHES, RISK MITIGATION, NATURAL-WATERS

Abstract

Biodegradation of the organophosphate insecticide chlorpyrifos (O,O-diethyl O-(3,5,6-trichloropyridin-2-yl) phosphorothioate) in sediments from wetlands and agricultural drains in San Joaquin Valley, CA was investigated. Sediments were collected monthly, spiked with chlorpyrifos, and rates of chlorpyrifos degradation were measured using a standardized aerobic biodegradation assay. Phosphoesterase enzyme activities were measured and phosphotriesterase activity was related to observed biodegradation kinetics. First-order biodegradation rates varied between 0.02 and 0.69 day(-1), after accounting for abiotic losses. The average rate of abiotic chlorpyrifos hydrolysis was 0.02d(-1) at pH 7.2 and 30 degrees C. Sediments from the site exhibiting the highest chlorpyrifos degradation capacity were incubated under anaerobic conditions to assess the effect of redox conditions on degradation rates. Half-lives were 5 and 92 days under aerobic and anaerobic conditions, respectively. There was a consistent decrease in observed biodegradation rates at one site due to permanently flooded conditions prevailing during one sampling year. These results suggest that wetland management strategies such as allowing a wet-dry cycle could enhance degradation rates. There was significant correlation between phosphotriesterase (PTE) activity and the chlorpyrifos biotransformation rates, with this relationship varying among sites. PTE activities may be useful as an indicator of biodegradation potential with reference to the previously established site-specific correlations. (C) 2012 Elsevier B.V. All rights reserved.