Diazinon Mitigation in Constructed Wetlands: Influence of Vegetation

Abstract

In intensively cultivated areas, agriculture is a significant source of pesticides associated with storm runoff. When these pollutants enter aquatic receiving waters, they have potential to damage nearby aquatic ecosystems. Constructed wetlands are a best management practice (BMP) designed to help alleviate this potential problem. A constructed wetland system (180×30 m) comprised of a sediment retention basin and two treatment cells was used to determine fate and transport of a simulated storm runoff event containing the insecticide diazinon and suspended sediment. Wetland water, sediment, and plant samples were collected spatially and temporally over 55 d. Results indicated that 43% of the study's measured diazinon mass was associated with plant material, while 23 and 34% were measured in sediment and water, respectively. Mean diazinon concentrations in water, sediment, and plants for the 55-d study were 18.1±4.5 μg/l, 26.0±8.0 μg/kg, and 97.8± 10.7 μg/kg, respectively. Aqueous concentrations fluctuated in the wetlands between 51-86 μg/l for the first 4 h of the experiment; however, by 9 h, aqueous concentrations were approximately 16 μg/l. During the 55 d experiment, 0.3 m of rainfall contributed to fluctuations in diazinon concentrations. Results of this experiment can be used to model future design specifications for mitigation of diazinon and other pesticides.

Mitigation of Wastewater-Borne Chlorpyrifos in Constructed Wetlands: the Role of Vegetation on Partitioning

“…Transformations in the present study included microorganism degradation, plant uptake, volatilization into the air, and natural photolysis. These transformations were similar to those previously described [26][27][28]. The significant decrease in substrate chlorpyrifos between the initial and terminal stages of the experiment suggest that the potential of chlorpyrifos transformation increased over the course of the experiment.…”

Environmental quality research in the Beasley Lake watershed, 1995 to 2007: Succession from conventional to conservation practices

“…Fluometuron was much more persistent under flooded versus 12% air filled pore space incubation, while atrazine was rapidly incorporated into soil bound components in both circumstances. In a simulated storm runoff experiment to evaluate pesticide fate in the BLW constructed wetland, water dosed with diazinon was added at the wetland entrance for 4 h, and diazinon was monitored for the subsequent 55 days (Moore et al 2007a). Over 40% of the pesticide was measured in plants within the wetland, demonstrating the contribution of vegetation to pollutant processing.…”

A decade of conservation effects assessment research by the USDA Agricultural Research Service: Progress overview and future outlook

“…Vegetative filter practices such as constructed wetlands and vegetated drainage ditches have been examined as a possible remediation measure. In the Beasley Lake Watershed in Mississippi, a constructed wetland receiving simulated storm runoff resulted in 43% to 76% of the pesticides being sorbed to plant material (Moore et al 2007(Moore et al , 2009). Herbicide concentrations were decreased 22% to 32% by the same wetland in a later study with a simulated runoff event .…”