Tissue distribution, isozyme abundance and sensitivity to chlorpyrifos-oxon of carboxylesterases in the earthworm Lumbricus terrestris

A laboratory-based study was conducted to determine the basal carboxylesterase (CbE) activity in different tissues of the earthworm Lumbricus terrestris, and its sensitivity to the organophosphate (OP) pesticide chlorpyrifos-oxon (CPx). Carboxylesterase activity was found in the pharynx, crop, gizzard, anterior intestine, wall muscle and reproductive tissues of L. terrestris, and multiple tissue-specific isozymes were observed by native gel electrophoresis. Esterase activity and sensitivity to CPx inhibition varied on a tissue- and substrate-specific basis, suggesting isoforms-specific selectivity to OP-mediated inhibition. Three practical issues are recommended for the use of earthworm CbE activity as a biomarker of pesticide exposure: (i) CbE should be measured using several routine substrates, (ii) it should be determined in selected tissues instead of whole organism homogenate, and (iii) earthworm CbE activity should be used in conjuncture with other common biomarkers (e.g., ChE) within a multibiomarker approach to assess field exposure of OPs, and potentially other agrochemicals.     

2003~2020年黄河内蒙古段干流水质演变趋势

为全面了解黄河流域内蒙古段近年来的水环境质量状况及其变化趋势,基于流域内5个监测断面2003~2020年的水质数据,使用主成分分析、聚类分析和长短时记忆模型等多源数据分析方法,结合改进的综合水质标识指数,探究了黄河流域水质的时空变化特征. 结果表明,流域水质状况整体向好并稳定. 时间特征方面,汛期和非汛期水质的主要影响因素存在显著差异,主要与农业灌溉用水和汛期水量增大有关;空间特征方面,可将5个监测断面归为3类,汛期的主要影响因素具有时间特征,而非汛期3类监测断面的水质差异主要由其周边城市的用水结构决定. LSTM模型的预测值变化趋势与真实值拟合效果良好,可对黄河内蒙古段的水质指标进行有效的预测评价,可为黄河干流各河段水质达标控制与管理提供科学依据.