北京市再生水灌区典型新型有机污染物的水文地球化学研究

Irrigation with reclaimed water is an important way to support the water demand of cities located in semi-arid areas, where groundwater supplies most water resources for industrial and domestic need. However, the groundwater quality and public health may suffer threatens from unqualified reclaimed water with various pollutants, especially from those new emerging organic pollutants that have not yet been listed into the monitoring and evaluating system in our country. It’s important and urgent to carry studies on these new emerging organic contaminants in groundwater to supplement the water quality assessment system. Tongzhou and Daxing suburb at southeast Beijing is one of the main reclaimed water irrigation area in Beijing City, about 600km2 of area with more than 40 years history of reclaimed water irrigation. This study will investigate the concentration, distribution, source and hydrogeochemistry behavior of some new emerging organic pollutants, including polycyclic aromatic hydrocarbons (PAHs), atrazine and its transformation products, pharmaceuticals and personal care croducts(PPCPs), perfluoroalkyl compounds (PFASs), in the Tongzhou-Daxing reclaimed water irrigation area. Researches on groundwater through hydrogeochemical approach could be originated to more than 2000 years ago, and the development of isotope analysis in recent years provided an effective method to trace nitrate or other pollutants in groundwater. In this study, the combination of hydrogeochemistry and stable isotope approaches would be applied to investigate the transportation and transformation behavior of the new emerging organic pollutants in rainfall water-surface water-groundwater system. It was anticipated that the results of this work would provide scientific data for the sustainable management of groundwater resources in Beijing City and other areas.

利用再生水灌溉是半干旱地区保障供水的重要途径，北京市东南郊大兴、通州再生水灌区是北京市利用再生水灌溉的主要地区，已有40多年再生水灌溉历史。再生水可能引入大量未被列入地下水质量监控的新型有机污染物到地下水环境中，为确保首都供水安全，开展北京市地下水中典型新型有机污染物的调查与研究工作显得尤为迫切而且必要。本项目提出在北京市东南郊再生水灌区开展农田及地下水中典型新型有机污染物的调查工作，查明地下水中多环芳烃、阿特拉津及其降解产物、典型药物和个人护理品化合物、全氟化合物等新型有机污染物的污染水平和分布状况。借助水文地球化学和稳定同位素相结合的分析手段，识别有机污染物的来源，探讨典型新型有机污染物在大气水-地表水-地下水系统的迁移转化行为。研究成果将为首都北京及其他地区地下水资源的科学管护提供借鉴。

再生水灌溉可能引入大量未被列入地下水质量监控的新型有机污染物到地下水环境中，本项目提出在北京市东南郊再生水灌区开展农田及地下水中典型新型有机污染物的调查工作，追溯地下水污染物的主要来源，探索污染物的水文地球化学行为，评估地下水典型新污染物的健康风险。通过研究发现，灌区地下水全氟化合物（PFASs）总量位于0.01~13.58 ng/L之间，且全氟羧酸类化合物（PFCAs）的检出率高于全氟磺酸类化合物（PFSAs）。药物与个人护理品（PPCPs）总量位于15.5~1230.6ng/L之间，以卡马西平、阿特拉津和磺胺甲恶唑检出最多。位于灌区中部的西田阳垃圾填埋场对周边地下水的PFASs污染具有一定贡献，但尚未构成生态风险。灌区含水层富水性北高南低，地下水流向总体呈西北向东南方向。灌区PFAS含量分布亦呈现西北向东南逐渐衰减之势，反映了污染物随地下水流的迁移逐渐被过滤而浓度递减的水文地球化学特征。计算PFOA与PFOS的健康危害指数表明，通过饮用地下水摄入的PFOA和PFOS不会给居民健康带来风险。研究结果对于了解首都北京地下水新新有机污染物现状以及科学管护地下水资源提供支撑。