Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, P.O. Box 7050, 750 07, Uppsala, Sweden.
Ecotoxicology. 2012 Nov;21(8):2398-408. doi: 10.1007/s10646-012-0995-z. Epub 2012 Sep 6.
We studied the fate and bioavailability of insecticides in short-term experiments (48 h) with different hydrophobicity (3.8 pM carbofuran, 3.0 pM lindane, and 5.3 pM chlorpyrifos) across gradients in dissolved organic matter (low-, medium-, and high-DOM) in freshwater microcosms, mimicking runoff events of pesticides. The effects of biofilms were studied by including treatments with biofilms cultivated under different DOM-concentrations. The presence of biofilms negatively affected chlorpyrifos water concentrations, indicating rapid sorption of this hydrophobic pesticide, while lindane concentrations instead increased and carbofuran concentrations were unaffected. Associations of lindane and chlorpyrifos with biofilms were 1.6-2.0 times higher in low- and high-DOM than in medium-DOM treatments, indicating that sorption was affected not only by the quantity, but also by the quality of DOM. Although the proportion of pesticides recovered in biofilms was consistently less than 1 % of added pesticide, pesticide concentrations in biofilms were on average more than 75- (carbofuran) and 382-times (lindane) higher than those in water. Snail accumulation of all three pesticides was significantly affected by DOM-concentrations and correlated to pesticide hydrophobicity, but the relationships were not straightforward. For example, carbofuran uptake in treatments without biofilms was higher in low-DOM than in medium- and high-DOM treatments, while chlorpyrifos uptake instead increased across the DOM-gradient. Biofilms played a role only for the uptake of chlorpyrifos, which decreased markedly in the presence of biofilms. Bioconcentration factors (BCF) calculated for snails and biofilms differed for the three pesticides and were related to their sorption behaviour (i.e., hydrophobicity). The relative proportion of pesticide uptake through biofilm consumption was consistently less than 2 %, showing that passive uptake was by far the predominant uptake pathway for all three pesticides.
我们在淡水微宇宙中进行了短期实验（48 小时），研究了不同疏水性（3.8 pM 克百威、3.0 pM 林丹和 5.3 pM 毒死蜱）的杀虫剂在溶解有机物（低、中、高 DOM）梯度中的命运和生物利用度，模拟了农药径流事件。通过包括在不同 DOM 浓度下培养的生物膜处理，研究了生物膜的影响。生物膜的存在对毒死蜱水浓度产生负面影响，表明这种疏水性农药迅速吸附，而林丹浓度增加，克百威浓度不受影响。与生物膜结合的林丹和毒死蜱在低和高 DOM 处理中比在中 DOM 处理中分别高出 1.6-2.0 倍，表明吸附不仅受 DOM 数量的影响，还受 DOM 质量的影响。尽管从添加的农药中回收的农药在生物膜中的比例始终小于 1%，但生物膜中的农药浓度平均比水中高 75-（克百威）和 382-倍（林丹）。三种农药在蜗牛中的积累均受到 DOM 浓度的显著影响，并与农药疏水性相关，但关系并不直接。例如，在没有生物膜的处理中，低 DOM 处理中克百威的吸收高于中 DOM 和高 DOM 处理，而氯蜱的吸收则在 DOM 梯度中增加。生物膜仅对氯蜱的吸收起作用，而氯蜱的吸收在生物膜存在下明显下降。为蜗牛和生物膜计算的生物浓缩因子（BCF）因三种农药而异，并与它们的吸附行为（即疏水性）有关。通过生物膜消耗吸收农药的相对比例始终小于 2%，表明被动吸收是所有三种农药的主要吸收途径。
