Lin C H, Lerch R N, Garrett H E, George M F
Center for Agroforestry, School of Natural Resources, University of Missouri, Columbia, MO 65211, USA.
J Environ Qual. 2008 Jan 4;37(1):196-206. doi: 10.2134/jeq2006.0503. Print 2008 Jan-Feb.
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 assess the bioremediation capacity of five forage species to enhance atrazine (ATR) dissipation in the environment via plant uptake and degradation and detoxification in the rhizosphere. Results suggested that the majority of the applied ATR remained in the soil and only a relatively small fraction of herbicide leached to leachates (<15%) or was taken up by plants (<4%). Biological degradation or chemical hydroxylation of soil ATR was enhanced by 20 to 45% in forage treatment compared with 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 d 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.
一个合理的多物种植被缓冲带设计应纳入那些有助于在缓冲带中快速降解和封存沉积除草剂的物种。开展了一项田间蒸渗仪研究，设置了六种不同的地被植物（裸地、果园草、高羊茅、梯牧草、草地早熟禾和柳枝稷），以评估五种饲草物种通过植物吸收、根际降解和解毒来增强莠去津（ATR）在环境中消散的生物修复能力。结果表明，大部分施用的ATR仍留在土壤中，只有相对较小比例的除草剂淋溶到渗滤液中（<15%）或被植物吸收（<4%）。与对照相比，饲草处理使土壤中ATR的生物降解或化学羟基化提高了20%至45%。在土壤中残留的ATR中，柳枝稷将80%以上降解为毒性较小的代谢物，施用后25天，其中47%的残留转化为移动性较小的羟基化代谢物。饲草处理中N-脱烷基化ATR代谢物的降解与微生物生物量碳增加之间的强相关性表明，饲草促进了根际生物降解的增强。羟基化ATR降解产物是柳枝稷和高羊茅组织中主要的ATR代谢物。相比之下，N-脱烷基化代谢物是在其他冷季物种中发现的主要降解产物。暖季和冷季物种之间代谢物模式的差异表明了它们不同的解毒机制，这也与它们对ATR暴露的耐受性有关。基于这项研究，建议将柳枝稷用于旨在降低ATR毒性和迁移性的河岸缓冲带，因为它具有高耐受性和强大的降解能力。
