Schulz R, Moore M T, Bennett E R, Milam C D, Bouldin J L, Farris J L, Smith S, Cooper C M
USDA-Agricultural Research Service, National Sedimentation Laboratory, P.O. Box 1157, Oxford, Mississippi 38655, USA.
Arch Environ Contam Toxicol. 2003 Oct;45(3):331-6. doi: 10.1007/s00244-003-2170-2.
Methyl-parathion (MeP) was introduced into constructed wetlands for the purpose of assessing the importance of distance from the source of contamination and the role of emergent vegetation on the acute toxicity to Hyalella azteca (Crustacea: Amphipoda). A vegetated (90% cover: mainly Juncus effuses) and a nonvegetated wetland (each with a water body of 50 x 5.5 x 0.2 m) were each exposed to a simulated MeP storm runoff event. H. azteca was exposed for 48 h in the laboratory to water samples taken from the wetlands at a distance of 5, 10, 20, and 40 m from the pesticide inlet 3 h, 24 h, 96 h, and 10 days following application. Methyl-parathion was detected throughout the nonvegetated wetland, whereas the pesticide was only transported halfway through the vegetated wetland. A repeated-measure three-way analysis of variance (ANOVA) using time, location, and vegetation indicated significantly lower toxicity in the vegetated wetland. Furthermore, the mortality decreased significantly with both increasing distance from the inlet and time (48-h LC50 +/- 95% CI: 9.0 +/- 0.3 microg/L). A significant three-way interaction of time x vegetation x location confirmed higher toxicity at the inlet area of the nonvegetated wetland immediately after contamination. Significant linear regressions of maximum mortality (independent of time) versus distance from the pesticide inlet indicated that 44 m of vegetated and 111 m of nonvegetated wetland would reduce H. azteca mortality to < or = 5%. These results suggest that vegetation contributes to reduced MeP effects in constructed wetlands.
为了评估距污染源的距离以及挺水植物对墨西哥高原钩虾（甲壳纲：端足目）急性毒性的作用，将甲基对硫磷（MeP）引入人工湿地。一个有植被的湿地（植被覆盖率90%：主要是灯心草）和一个无植被的湿地（每个湿地水体为50×5.5×0.2米）分别暴露于模拟的MeP暴雨径流事件。在施用农药3小时、24小时、96小时和10天后，从距农药入口5米、10米、20米和40米处的湿地采集水样，在实验室中让墨西哥高原钩虾暴露于这些水样中48小时。在整个无植被湿地中都检测到了甲基对硫磷，而该农药在有植被的湿地中只传输到了一半的距离。使用时间、位置和植被进行的重复测量三因素方差分析（ANOVA）表明，有植被的湿地毒性显著较低。此外，随着距入口距离的增加和时间的推移，死亡率显著降低（48小时LC50±95%置信区间：9.0±0.3微克/升）。时间×植被×位置的显著三因素交互作用证实，在无植被湿地受污染后立即在入口区域毒性更高。最大死亡率（与时间无关）与距农药入口距离的显著线性回归表明，44米的有植被湿地和111米的无植被湿地将使墨西哥高原钩虾死亡率降至≤5%。这些结果表明，植被有助于降低人工湿地中MeP的影响。
