电子垃圾污染土壤的典型持久性有机污染物二次排放规律及其区域影响

As the largest e-waste recycling site in the world, China has been facing serious environmental pollution, especially for the persistent organic pollutants (POPs). Although most of the rude recycling techniques have been banned with the implement of the new recycling policy, POPs that deposited in the soil could be released again and cause a secondary pollution. The research of exchange between polluted soil and atmosphere will be of great help to manage the transfer and emission of e-waste related pollutants. The objectives of the present study are: (1) using a high-volume active air sampler to discover the effect of daily environment parameters changings (e.g. temperature, wind speed, etc.) to the variability of POPs concentrations in the air, and to find out the diel variations of technical POPs, such as polychlorinated biphenyl (PCBs) and chlorinated paraffins(CPs), in the atmosphere near the e-waste polluted area; (2) using a fugacity sampler to find out the impact of the seasonal variation to the soil-air exchanges of PCBs and CPs between polluted soil and atmosphere; (3) using the enantiomer fractions of chiral PCBs to discover the source of POPs in the atmosphere; (4) using Fugacity Approach to estimate the exchange flux and capacity of PCBs and CPs in the e-waste polluted area, and using Gauss Diffusion Model to assess the regional impact of e-waste pollution to the surrounding environment. This research also aims to highlight the importance of the e-waste pollution control and to give advice to the site management and remediation.

中国是全球最大的电子垃圾处理地，原始的回收方式导致大量污染物，特别是持久性有机污染物(POPs)释放到环境中。随着政策法规的出台，粗放式回收方式逐渐被取缔。然而污染土壤的有机污染物受环境因素影响可能再次释放出来，成为新的二次污染源。因此研究电子垃圾污染土壤与大气间的交换趋势，对控制污染物的迁移、扩散及二次污染具有重要意义。本研究拟采用大流量采样器考察电子垃圾污染区大气典型污染物(多氯联苯和氯化石蜡)的日变化规律，探究温度等环境参数及土壤理化性质对大气污染物含量的影响。利用逸度采样器对污染土壤与大气污染物的季节性交换过程进行评估，考察不同季节环境参数变化对污染土壤二次排放的影响。利用手性对映体比值考察大气中污染物来源。利用逸度模型估算土壤与大气间污染物的交换通量，根据高斯模型考察污染物在周边环境的扩散，评估电子垃圾污染对周边地区的区域环境影响。研究结果将服务于电子垃圾污染区的场地管理与修复。

我国是全球最大的电子垃圾处理地之一，粗犷的回收方式导致大量的有机污染物释放到环境中。污染土壤中的有机污染物，由于环境条件的变化，可能再次释放，形成二次污染。本研究对广东清远市典型电子垃圾污染区的研究，测得电子垃圾污染土壤中PCBs浓度为542-4592 ng/g，PBDEs浓度（不含BDE209）为32-2130 ng/g；该地区大气中PCBs颗粒态浓度27.6-1704 pg/m3，气态浓度270-15500 pg/m3；大气颗粒态PBDEs总浓度为13.3-234 pg/m3；气态PBDEs总浓度为11.0-430 pg/m3。就污染物组成来看，以低氯取代的PCBs和低溴取代的PBDEs为主，说明该地区污染物主要来自电子垃圾焚烧过程中和剩余灰烬中污染物的挥发。逸度采样器和逸度模型计算结果显示：首先，逸度模型的测定结果能够更准确的反映污染物在土壤和大气间的扩散迁移趋势，特别是对于低分子量的污染物；其次，电子垃圾污染区污染土壤仍然是低氯PCBs和低溴PBDEs的二次排放源。说明虽然焚烧等非法电子垃圾回收方式被取缔，但污染的土壤仍然是诸多有机污染物的二次排放源，还需加大控制和治理力度，防止污染物进一步扩散，危害人体健康和生态环境。