|Lerch, Robert - Bob|
Submitted to: Symposium on the Fate and Chemistry of Modern Pesticides Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 9/19/2006
Publication Date: 11/28/2006
Citation: Lin, C.H., Lerch, R.N., Garrett, H.E., George, M.F. 2006. Phytoremediation of atrazine by five forage grass species: transformation, uptake and detoxification [abstract]. In: Proceedings of Symposium on the Fate and Chemistry of Modern Pesticides. 10th Symposium on Chemistry and Fate of Modern Pesticides, November 26-29, 2006, Almeria, Spain. p. 291. Interpretive Summary:
Technical Abstract: A sound multi-species vegetation buffer design should incorporate the species that facilitate rapid degradation and sequestration of deposited herbicides in the buffer. A field lysimeter study with six different ground covers (bare ground, orchardgrass, tall fescue, timothy, smooth bromegrass, and switchgrass) was established to evaluate their phytoremediation capacity for transformation, uptake, and detoxification of atrazine (ATR). Results suggested that the majority of the applied ATR remained in the soil and only a relatively small fraction of herbicide leached to shallow groundwater (<15%) or was taken up by plants (<3%). Biological degradation or chemical hydroxylation of soil ATR was enhanced by 20% to 45% in forage treatment compared to the control. Of the ATR residues remaining in soil, switchgrass degraded more than 80% to less toxic metabolites, with 47% of these residues converted to the less mobile hydroxylated metabolites 25 days after application. The strong correlation between the degradation of N-dealkylated ATR metabolites and the increased microbial biomass carbon in forage treatments suggested that enhanced biological degradation in the rhizosphere was facilitated by the forages. Hydroxylated ATR degradation products were the predominant ATR metabolites in the tissues of switchgrass and tall fescue. In contrast, the N-dealkylated metabolites were the major degradation products found in the other cool season species. The difference in metabolite patterns between the warm and cool season species demonstrated their contrasting detoxification mechanisms, which also related to their tolerance to ATR exposure. Based on this study, switchgrass is recommended for use in riparian buffers designed to reduce ATR toxicity and mobility due to its high tolerance and strong degradation capacity.