School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China; Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China; Centre of Sustainable Design and Environment, Faculty of Design and Environment, Technological and Higher Education Institute of Hong Kong, Tsing Yi Road, Hong Kong, China.
Sci Total Environ. 2018 Apr 1;619-620:1153-1162. doi: 10.1016/j.scitotenv.2017.11.159. Epub 2017 Nov 29.
Polybrominated diphenyl ethers (PBDEs) are common pollutants released from electronic waste (e-waste) dismantling and recycling activities. Our city-wide survey of agricultural soils in Qingyuan (40 sampling sites), where e-waste recycling has been active, observed exceedance of PBDEs above background levels (average of 251.9ngg, 87 times the regional baseline concentration) together with elevated levels of metals/metalloids at the contamination hotspots, such as As (180.4mgkg), Cu (100.7mgkg), Zn (93.4mgkg), Pb (37.8mgkg), Cr (15.1mgkg), and Cd (0.3mgkg). Hence, a twenty-cycle batch sorption test on composite soil samples from the e-waste site was conducted to study the fate of BDE-28 (2,4,4'-tribromodiphenyl ether) and BDE-99 (2,2',4,4',5-pentabromodiphenyl ether) under the influence of co-existing trace elements (TEs) (Cu, Pb, Zn, and Cd, which exceeded Chinese Environmental Quality Standard for Soils), dissolved organic matter (extracted from local peat), and locally available commercial fertilizer. The results showed that the presence of TEs barely affected the sorption of BDEs, probably because the low concentration of BDEs in the environment resulted in nearly complete sorption onto the soil. In contrast, metals sorption onto soil was promoted by the presence of BDEs. The mobility of BDE-28 was higher than BDE-99 in water leaching tests, while the leaching concentration of BDE-99 was further reduced in simulated acid rain possibly due to protonation of π-accepting sites in soil organic matter. In the freshly spiked soil, BDEs of greater hydrophobicity and larger molecular size exhibited higher bioavailability (due to greater affinity to Tenax extraction), which was contrary to the field contaminated soil. Similarly, the co-occurrence of metals and fertilizer increased the bioavailability of newly sorbed BDE-99 more than BDE-28 in the soil. These results illustrate the need to holistically assess the fate and interactions of co-existing organic and inorganic pollutants in the agricultural soils.
多溴联苯醚（PBDEs）是电子废物（e-waste）拆解和回收活动释放的常见污染物。我们对清远市（40 个采样点）农业土壤进行了全市范围的调查，该地区的电子废物回收活动活跃，结果发现 PBDEs 超过了背景水平（平均为 251.9ngg，是区域基线浓度的 87 倍），同时在污染热点地区的金属/类金属含量也升高，如 As（180.4mgkg）、Cu（100.7mgkg）、Zn（93.4mgkg）、Pb（37.8mgkg）、Cr（15.1mgkg）和 Cd（0.3mgkg）。因此，在电子废物场地的复合土壤样品上进行了 20 个循环批量吸附试验，以研究共存痕量元素（TEs）（Cu、Pb、Zn 和 Cd，超过了中国土壤环境质量标准）、溶解有机物（从当地泥炭中提取）和当地可利用商业肥料对 BDE-28（2,4,4'- 三溴二苯醚）和 BDE-99（2,2',4,4',5- 五溴二苯醚）的命运的影响。结果表明，TEs 的存在几乎不会影响 BDEs 的吸附，这可能是因为环境中 BDEs 的浓度较低，导致几乎完全被土壤吸附。相比之下，金属在土壤中的吸附受到 BDEs 的促进。BDE-28 在水浸出试验中的迁移性高于 BDE-99，而在模拟酸雨条件下 BDE-99 的浸出浓度进一步降低，这可能是由于土壤有机质中π-接受体的质子化。在新鲜添加的土壤中，疏水性和较大分子量的 BDEs 表现出更高的生物可利用性（由于对 Tenax 提取的亲和力更大），这与受污染的田间土壤相反。同样，金属和肥料的共同存在增加了新吸附的 BDE-99 的生物可利用性，高于 BDE-28 在土壤中的生物可利用性。这些结果表明需要全面评估农业土壤中共存有机和无机污染物的归宿和相互作用。
