Ecotoxicology Lab, Fac. Environmental Science and Biochemistry, University of Castilla-La Mancha, Toledo, Spain.
Department of Animal Biology, Soil Science and Geology, University of La Laguna, Canary Islands, Spain.
Sci Total Environ. 2018 Jan 15;612:1407-1416. doi: 10.1016/j.scitotenv.2017.09.043. Epub 2017 Sep 25.
Earthworms contribute, directly and indirectly, to contaminant biodegradation. However, most of bioremediation studies using these annelids focus on pollutant dissipation, thus disregarding the health status of the organism implied in bioremediation as well as the recovery of indicators of soil quality. A microcosm study was performed using Lumbricus terrestris to determine whether earthworm density (2 or 4individuals/kg wet soil) and the time of exposure (1, 2, 6, 12, and 18wk) could affect chlorpyrifos persistence in soil initially treated with 20mg active ingredientkg wet soil. Additionally, selected earthworm biomarkers and soil enzyme activities were measured as indicators of earthworm health and soil quality, respectively. After an 18-wk incubation period, no earthworm was killed by the pesticide, but clear signs of severe intoxication were detected, i.e., 90% inhibition in muscle acetylcholinesterase and carboxylesterase (CbE) activities. Unexpectedly, the earthworm density had no significant impact on chlorpyrifos dissipation rate, for which the measured half-life ranged between 30.3d (control soils) and 44.5d (low earthworm density) or 36.7d (high earthworm density). The dynamic response of several soil enzymes to chlorpyrifos exposure was examined calculating the geometric mean and the treated-soil quality index, which are common enzyme-based indexes of microbial functional diversity. Both indexes showed a significant and linear increase of the global enzyme response after 6wk of chlorpyrifos treatment in the presence of earthworms. Examination of individual enzymes revealed that soil CbE activity could decrease chlorpyrifos-oxon impact upon the rest of enzyme activities. Although L. terrestris was found not to accelerate chlorpyrifos dissipation, a significant increase in the activity of soil enzyme activities was achieved compared with earthworm-free, chlorpyrifos-treated soils. Therefore, the inoculation of organophosphorus-contaminated soils with L. terrestris arises as a complementary bioremediation strategy in terms of recovery of soil biochemical performance and quality.
蚯蚓直接或间接地促进污染物的生物降解。然而，大多数使用这些环节动物进行生物修复的研究都侧重于污染物的消散，从而忽略了生物修复中生物体的健康状况以及土壤质量指标的恢复。本研究采用赤子爱胜蚓进行了一项微宇宙研究，以确定蚯蚓密度（2 或 4 条/千克湿土）和暴露时间（1、2、6、12 和 18 周）是否会影响最初用 20mg 有效成分/kg 湿土处理的土壤中氯吡硫磷的持久性。此外，还测量了选定的蚯蚓生物标志物和土壤酶活性，分别作为蚯蚓健康和土壤质量的指标。在 18 周的孵育期后，没有蚯蚓被杀虫剂杀死，但检测到明显的严重中毒迹象，即肌肉乙酰胆碱酯酶和羧酸酯酶（CbE）活性抑制 90%。出乎意料的是，蚯蚓密度对氯吡硫磷消解速率没有显著影响，测量的半衰期范围在 30.3d（对照土壤）和 44.5d（低蚯蚓密度）或 36.7d（高蚯蚓密度）之间。通过计算几何平均值和处理土壤质量指数（这是微生物功能多样性的常见基于酶的指标），研究了几种土壤酶对氯吡硫磷暴露的动态响应。在有蚯蚓存在的情况下，氯吡硫磷处理 6 周后，这两个指数都显示出土壤酶整体反应的显著线性增加。对个别酶的检查表明，土壤 CbE 活性可以降低氯吡硫磷氧对其他酶活性的影响。尽管赤子爱胜蚓没有加速氯吡硫磷的消解，但与无蚯蚓、氯吡硫磷处理的土壤相比，土壤酶活性显著增加。因此，将赤子爱胜蚓接种到有机磷污染的土壤中，可以作为一种补充生物修复策略，恢复土壤的生化性能和质量。
