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Seasonal effects on microbial transformation rates of an herbicide in a freshwater stream: Application of laboratory data to a field site
Author(s) -
Lewis David L.,
Freeman Leonard F.,
Watwood Mary Elizabeth
Publication year - 1986
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.5620050903
Subject(s) - dilution , environmental chemistry , transformation (genetics) , surface water , litter , chemistry , environmental science , ecology , hydrology (agriculture) , biology , environmental engineering , biochemistry , physics , geotechnical engineering , engineering , gene , thermodynamics
Seasonal effects on microbial transformation rates of an herbicide, 2,4‐dichlorophen‐oxyacetic acid butoxyethyl ester (2,4‐DBE), in a freshwater stream were investigated using low concentrations (less than 100 μg L −1 ) of the herbicide mixed with an inert dye, rhodamine WT, to correct for dilution. Although water temperatures decreased from 22 ± 0.5 to 8.0 ± 0.5°C and water velocities decreased from 0.09 ± 0.01 to 0.03 ± 0.003 m s −1 , microbial transformation rates, as indicated by pseudo‐first‐order transformation rate coefficients, increased as much as threefold in the cold months over those in the spring and summer. The increased winter transformation rates were associated with leaf‐litter accumulation, which provided additional colonized surface area in the stream. Therefore, the increased colonized surface area more than compensated for the effects of temperature and water velocity (under conditions of mass‐transport limitation) that otherwise would have reduced microbial transformation rates in the winter months.