School of Geography, Geology and the Environment, Keele University, Keele ST5 5BG, United Kingdom.
School of Geography, Geology and the Environment, Keele University, Keele ST5 5BG, United Kingdom.
Ecotoxicol Environ Saf. 2018 Oct 30;162:334-340. doi: 10.1016/j.ecoenv.2018.06.087. Epub 2018 Jul 11.
Drinking water treatment residuals (WTRs), the by-product of water clarification processes, are routinely disposed of via landfill however there is a growing body of research that demonstrates the material has great potential for beneficial use in environmental applications. Application to agricultural land is one option showing great promise (i.e. a low cost disposal route that provides organic matter input to soils and other potential benefits), however questions remain as to the impact such applications may have on earthworm survival and behaviour and also on the potential effects it may have on soil porewater chemistry. This study examined the leachability of elements within two types of WTRs (one Al- and one Fe- based) from England via 0.001 M CaCl solution, at varying pH, and via the Community Bureau of Reference (BCR) sequential extraction scheme. Earthworm avoidance, survival, growth, reproduction and element concentrations were examined in WTR-amended sandy soils (0%, 5%, 10%, 20% w/w), while soil porewaters were also recovered from experimental units and examined for element concentrations. The results revealed leachable element concentrations to be very low in both types of WTRs tested and so element leaching from these WTRs would be unlikely to pose any threat to ecosystems under typical agricultural soil conditions. However, when the pH was lowered to 4.4 there was a substantial release of Al from the Al-WTRs (382 mg/kg). Soil porewater element concentrations were influenced to some degree by WTR addition, warranting further examination in terms of any potential implications for nutrient supply or limitation. Earthworm avoidance of WTR-amended soil was only observed for Al-WTRs and only at the maximum applied rate (20% w/w), while survival of earthworms was not affected by either WTR type at any application rate. Earthworm growth and reproduction (cocoon production) were not affected at a statistically significant level but this needs further examination over a longer period of exposure. Increased assimilation of Al and Fe into earthworm tissues was observed at some WTR application rates (maximum fresh weight concentrations of 42 mg/kg for Al and 167 mg/kg for Fe), but these were not at levels likely to pose environmental concerns.
饮用水处理残渣（WTRs）是水澄清过程的副产品，通常通过垃圾填埋处理。然而，越来越多的研究表明，该材料在环境应用中有很大的潜在用途。应用于农业土地是一种很有前途的选择（即低成本的处理途径，可为土壤提供有机物输入和其他潜在益处），但仍存在一些问题，例如这种应用可能对蚯蚓的生存和行为产生影响，以及对土壤孔隙水化学可能产生的潜在影响。本研究通过 0.001 M CaCl2 溶液在不同 pH 值下以及通过社区参考局（BCR）顺序提取方案，检查了来自英格兰的两种 WTR（一种基于 Al，一种基于 Fe）中的元素浸出率。在 WTR 改良的沙质土壤（0%、5%、10%、20%w/w）中，研究了蚯蚓的回避、生存、生长、繁殖和元素浓度，同时从实验单元中回收土壤孔隙水，并检查了元素浓度。结果表明，在测试的两种 WTR 中，可浸出元素浓度都非常低，因此在典型农业土壤条件下，这些 WTR 中的元素浸出不太可能对生态系统构成威胁。然而，当 pH 值降低到 4.4 时，Al-WTR 中大量释放出 Al（382mg/kg）。土壤孔隙水中的元素浓度在某种程度上受到 WTR 添加的影响，需要进一步研究任何对养分供应或限制的潜在影响。只有在最高添加率（20%w/w）下，Al-WTR 才会引起蚯蚓回避 WTR 改良土壤，而两种 WTR 类型在任何添加率下都不会影响蚯蚓的生存。蚯蚓的生长和繁殖（茧的产生）在统计学上没有受到显著影响，但这需要在更长的暴露时间内进一步研究。在某些 WTR 应用率下观察到 Al 和 Fe 被蚯蚓组织同化增加（最大新鲜重量浓度分别为 42mg/kg 的 Al 和 167mg/kg 的 Fe），但这些浓度不太可能引起环境关注。
