Ecological risk assessment of atrazine in North American surface waters.

摘要: The triazine herbicide atrazine (2-chloro-4-ethylamino-6-isopropyl-amino-s-triazine) is one of the most used pesticides in North America. Atrazine principally for control certain annual broadleaf and grass weeds, primarily corn but also sorghum, sugarcane, and, to a lesser extent, other crops landscaping. found many surface ground waters America, aquatic ecological effects are possible concern regulatory regulated communities. To address these concerns an expert panel (the Panel) was convened conduct comprehensive risk assessment. This assessment based on several newly suggested procedures included exposure hazard subcomponents as well overall Panel determined that use probabilistic techniques appropriate. Here, results this presented case study techniques. environmental concentrated monitoring data from Midwestern watersheds, area greatest analysis revealed concentrations rarely exceed 20 μg/L rivers streams were main focus Following storm runoff, biota lower-order may be exposed pulses greater than μg/L, exposures short-lived. considered lakes reservoirs. principal set developed by U.S. Geological Survey, which monitored residues 76 reservoirs 11 states 1992-1993. Residue some similar those persisted longer. widespread (92% occurrence), 90th percentile distribution early June July about 5 μg/L. Mathematical simulation models chemical fate generalize sites assess potential reduction application rates. Models evaluated, modified, calibrated against available validate could predict runoff. PRZM-2 overpredicted order magnitude, whereas GLEAMS underpredicted factor 2 5. Thus, not extrapolate regions both freshwater saltwater toxicity test results. Phytoplankton sensitive organisms, followed, decreasing sensitivity, macrophytes, benthic invertebrates, zooplankton, fish. inhibits photophosphorylation typically does result lethality or permanent cell damage short term. characteristic required different model understanding impact systems, where nonreversible usually assumed. In addition, recovery phytoplankton demonstrated. mesocosm field experiments, macrophytes reduced after However, populations quickly reestablished, even while water. Effects studies judged ecologically important only at 50 greater. Mesocosm experiments did reveal disruption either ecosystem structure function encountered environment (generally less). Based integration laboratory bioassay data, studies, watersheds high-use areas United States, concluded pose significant environment. Although inhibitory algae, phytoplankton, macrophyte production occur small vulnerable agricultural likely transient, quick system expected. A subset waters, with intensive atrazine, atrazine. Therefore, it recommended site-specific assessments conducted context uses ecosystems put effectiveness cost-benefit aspect any mitigation measures applied.