Chemical fate and transport of atrazine in soil gravel materials at agrichemical distribution facilities.

摘要

Gravel used to cover parking lots and roadways at retail agrichemical facilities in Illinois, USA, was studied to determine if relatively large concentrations of pesticides that resulted from past management problems were present. Excavations at a closed facility showed variation in pesticide distribution within the site. Pesticides were present below the gravel in two profiles, but the mechanism(s) for their movement were not clear. The influence of the physical and chemical properties of the gravel on the environmental fate of atrazine was investigated. All of the gravel samples collected and characterized contained atrazine and sufficient organic C to adsorb significant amounts of atrazine, thus retarding its movement through the gravel. Laboratory column leaching experiments suggested that much of the atrazine should leach from the gravel within 1-2 years. A field-scale test plot was constructed to study how atrazine moves through the gravel under controlled conditions. Atrazine was 'spilled'in the test plot. Atrazine moved from the gravel both vertically and horizontally. It was shown that formulated products spilled on gravel will leach, and that a single discrete spill can give rise to phantom spills whose occurrence and distribution were not related to any specific pesticide-management practice. The apparent lack of atrazine leaching from gravel appeared to be a transient phenomenon and/or the result of sampling limitations in previous studies. It was concluded that the contaminated gravel clearly posed a risk to groundwater quality.