Pyrethroid residues in sediment and water samples from mesocosm and farm pond studies of simulated accidental aquatic exposure

Abstract

This paper describes the residue analysis of water and hydrosoil samples taken from two separate large-scale aquatic ecotoxicology trials designed to assess the environmental fate and effects of the pyrethroids lambda-cyhalothrin and cypermethrin. Comparison of the results demonstrates the high degree of reproducibility of the chemical residue found the day after treatment using experimental mesocosms (lambda-cyhalothrin) as opposed to an in-use farm pond (cypermethrin). Both studies showed that pyrethroid residues were rapidly lost from the water column: residues of lambda-cyhalothrin were less than 2 ng litre-l following the final application of a cumulative seasonal exposure equivalent to twelve 'drift' and six 'run-off' events, each delivering a dose equivalent to that expected from a typical event under field conditions. Hydrosoil appeared to act as a sink for pyrethroid residues and, under the stringent test conditions of the mesocosm study, lambda-cyhalothrin residues reached 3-2 pg kg-l following the seasonal exposure described above. The cypermethrin farm-pond study illustrated the localised pattern of exposure expected under natural field conditions, with site topography and cultivation practices which represent an average 'worst case'. Residues in hydrosoil reached a maximum level of approximately 25 pug kg-' in one sampling zone at one interval, and thereafter declined to a level of < 9 pg kg-' within four months.

Relationship between biochemical biomarkers and pre‐copulatory behaviour and mortality in Gammarus pulex following pulse‐exposure to lambda‐cyhalothrin

“…As extrapolation to a higher tier is based on these simple tests, risk assessment may be protective, at least regarding the mortality of G pulex . In natural ecosystems the impact of insecticides may be buffered through adsorption to sediments38 and refuges from exposure 16. Thus, higher effect concentrations would consequently be needed in situ to cause impact on aquatic organisms.…”

Environmental Chemistry, Ecotoxicity, and Fate of Lambda-Cyhalothrin

“…Hydrosoil (sediment) appeared to act as a sink for lambda-cyhalothrin (Hadfield et al 1993). Under the stringent test conditions of the mesocosm study, lambdacyhalothrin residues in the hydrosoil (1.1% organic matter) reached 3.2 µg/kg following the seasonal exposure.…”

“…Similarly, in an investigation of the fate of both gamma-and lambda-cyhalothrin in laboratory-simulated rice paddy water, their concentrations decreased rapidly, with no gamma-cyhalothrin or lambda-cyhalothrin detected after 3 and 4 d, respectively ). Last, after simulating a seasonal exposure equivalent to 12 "drift" and 6 "runoff" events, each delivering a dose equivalent to that expected from a typical event under field conditions, the lambda-cyhalothrin concentration measured after the final application was less than 2 ng/L (Hadfield et al 1993). …”

Disappearance of endosulfan residues from seawater and sediment under laboratory conditions

“…4 The adsorption of lipophilic compounds by sediments plays an important role in pesticide absorption by aquatic organisms, and explains to a large degree why the toxicity of pesticides to wildlife is predominantly an aquatic rather than terrestrial problem 5. This is reflected by the number of studies published on the influence of pesticides on distinct aquatic ecosystems 6–13…”