Department of Environmental Sciences, University of California, Riverside, California 92521, USA.
Environ Sci Technol. 2010 Nov 15;44(22):8473-8. doi: 10.1021/es102277h.
Despite their strong hydrophobicity, recent studies showed widespread occurrence of pyrethroid in downstream surface waters bodies. In this work, the effect of dissolved organic carbon (DOC) on the sorption and desorption of pyrethroids in sediment was evaluated to understand the role of DOC in facilitating pyrethroid transport. Presence of DOC from three sources at 38 ± 2 mg L⁻¹ in the aqueous phase decreased pesticide sorption to a sediment by 1.7 to 38.9 times and increased their desorption by 1.2 to 41.4 times. The effect on pyrethroid sorption to the sediment was linear. In addition, interactions between DOC and pyrethroids, when taking place prior to the contact with sediment, decreased sorption of some pyrethroids even further, implying that DOC-pyrethroid complexs were relatively stable in solution. DOC sources with higher contents of carboxylic and phenolic groups were found to have a higher potential to associate with pyrethroids. The DOC-water partition coefficients (K(DOC)) obtained by solid-phase microextraction measurement were significantly correlated (P < 0.01) with K(d) values measured for the sediment. These results provide evidence that DOC increases the distribution of pyrethroids from the sediment to the solution phase and plays an important role in mobilizing pyrethroids in runoff and surface streams.
尽管拟除虫菊酯具有很强的疏水性，但最近的研究表明，它们广泛存在于下游地表水体中。在这项工作中，评估了溶解有机碳（DOC）对沉积物中拟除虫菊酯吸附和解吸的影响，以了解 DOC 在促进拟除虫菊酯迁移中的作用。在水相中存在来自三种来源的 38±2mg/L 的 DOC，使农药在沉积物中的吸附减少了 1.7 到 38.9 倍，并使它们的解吸增加了 1.2 到 41.4 倍。DOC 对拟除虫菊酯在沉积物中吸附的影响呈线性。此外，DOC 与拟除虫菊酯在与沉积物接触之前发生相互作用，进一步降低了一些拟除虫菊酯的吸附，这意味着 DOC-拟除虫菊酯复合物在溶液中相对稳定。发现含有更多羧酸和酚基团的 DOC 来源更有可能与拟除虫菊酯结合。通过固相微萃取测量获得的 DOC-水分配系数（K(DOC)）与沉积物中测量的 K(d)值显著相关（P<0.01）。这些结果表明，DOC 增加了拟除虫菊酯从沉积物向溶液相的分布，并在径流水和地表溪流中使拟除虫菊酯迁移发挥了重要作用。
