电子废物不当处置的重金属污染及其环境风险评价 Ⅲ.电子废物酸解、焚烧活动对小流域地表水和井水的金属污染

为了评价电子废物酸解、焚烧活动对当地小流域水体的金属污染,采集了广东省清远市龙塘镇地区泉水、水塘、水库、农灌渠、水田和水井中的水样,分析了各水样中的10种金属含量.研究结果表明,从电子废物酸解、焚烧核心区域的坡谷中采集的泉水受到了较严重的Pb污染,水中Pb浓度达到0.070mg·L-1,高于国家地表水环境质量标准(GB3838-2002)规定的III类水质标准.在酸解作坊边缘一个水塘的水样中检出了浓度分别高达64.82、56.37、2.164、0.200和6.649mg·L-1的Cu、Zn、Cr、Pb和Cd,均大大超过了III类水质标准,其中Cd超标1329.8倍,pH值只有2.05,电导率高达6890μS·cm-1,说明该水塘中的水基本是电子废物酸解活动排放的废水,并且已经通过下渗、地表径流等过程污染了小流域中的其他水体.虽然在农灌渠、水田、水井的水样中未检出超标的重金属浓度,但各种迹象说明,这些水体也已经受到了电子废物回收活动的影响,其中井水中电导率接近400μS·cm-1,远高于其他自然水体.来源于电子废物不当处置的重金属在这些水体中的累积值得关注,今后有必要开展更为持久、全面、系统的监测和研究.

Studies on Heavy Metal Contamination by Improper Handling of E-Waste and Its Environmental Risk Evaluation III. Heavy Metal Contamination of Surface Waters and Well Water by E-Waste Acid Treatment and Open Burning Activities

In order to evaluate metal contaminations to water of a small scale valley within the E-waste acid-treating and open-burning area,water samples of spring,pools,small dams,irrigation ditch,paddy farm and domestic water well were collected in Longtang Town,Qingyuan,Guangdong, China. Concentrations of Al,Cu,Zn,Mn,Mg,Ni,Cr,Co,Pb and Cd in the water samples were analyzed. It was found that the spring water was contaminated by Pb,and the concentration of Pb in the spring water was 0.070mg·L-1,higher than the maximal limitation (ML) of Pb in the three grade surface water standard (GB3838-2002). Extremely high Cu,Zn,Cr,Pb and Cd concentrations (64.82mg·L-1,56.37mg·L-1,2.164mg·L-1, 0.200mg·L-1 and 6.649mg·L-1) were detected in the water of a pool near an acid-treating workshop. The concentration of Cd in the pool water was 1329.8 folds of the ML of the three grade surface water standard,and its pH value was very low (2.08) and the electronic conductivity (EC) was very high (6890μS·cm-1),indicating that the water in the pool was almost comprised of the emission of the acid-treating activity. The contaminants were obviously transferred into the water of the whole small scale valley. Although there were no toxic metals at the levels being higher than the ML of the relevant standards or guidelines in the water samples collected from the irrigation ditch,paddy farm and domestic well,some evidences proving that the waters had been contaminated were observed,for example,the EC of the domestic well water reached up to 400μS·cm-1,being rather higher than many natural waters. The accumulations of the heavy metals in deposits of these water bodies are worth noting,and continuous monitoring and systematic assessment are requested.