title: Influences of aquatic plants on the fate of the pyrethroid insecticide lambda-cyhalothrin in aquatic environments.
abstract: Aquatic exposure assessments for pesticides are generally based on laboratory studies performed in water alone or water sediment systems. Although aquatic macrophytes, which include a variety of bryophytes, macroalgae, and angiosperms, can be a significant component of many aquatic ecosystems, their impact on pesticide fate is generally not included in exposure assessments. To investigate the influence of aquatic plants on the fate and behavior of the pyrethroid insecticide lambda (lambda)-cyhalothrin, two laboratory experiments (to assess adsorption and degradation) and an indoor microcosm study (to assess fate under semirealistic conditions) were conducted. In the laboratory studies, adsorption to macrophytes was extensive and essentially irreversible, and degradation occurred rapidly by cleavage of the ester bond. In the indoor microcosm, which contained water, sediment, and macrophytes from a pond, degradation was also rapid, with DT50 and DT90 values of less than 3 and 19 h, respectively, for dissipation from the water column and of less than 3 and 56 h, respectively, for the whole system. For adsorptive and readily degraded pesticides like lambda-cyhalothrin, we conclude that macrophytes have considerable influence on fate and behavior in surface waters.
authors.affiliation: Syngenta, Environmental Sciences Department, Jealott's Hill International Research Centre, Bracknell, Berkshire, United Kingdom, laurence.hand@syngenta.com
authors.forename: L H
authors.initials: LH
authors.lastname: Hand
authors.forename: S F
authors.initials: SF
authors.lastname: Kuet
authors.forename: M C
authors.initials: MC
authors.lastname: Lane
authors.forename: S J
authors.initials: SJ
authors.lastname: Maund
authors.forename: J S
authors.initials: JS
authors.lastname: Warinton
authors.forename: I R
authors.initials: IR
authors.lastname: Hill
mesh_terms: D000327:Adsorption; D001673:Biodegradation, Environmental; D001682:Biological Availability; D019015:Geologic Sediments / Q000737:chemistry; D007306:Insecticides / Q000493:pharmacokinetics*; D009570:Nitriles; D010944:Plants / Q000737:chemistry*; D011722:Pyrethrins / Q000493:pharmacokinetics*; D014874:Water Pollutants, Chemical / Q000493:pharmacokinetics*
chemical_list: D007306:Insecticides; D009570:Nitriles; D011722:Pyrethrins; D014874:Water Pollutants, Chemical; C037304:cyhalothrin