Elevated Levels of Polychlorinated Biphenyls in Plants, Air, and Soils at an E-Waste Site in Southern China and Enantioselective Biotransformation of Chiral PCBs in Plants
Elevated Levels of Polychlorinated Biphenyls in Plants, Air, and Soils at an E-Waste Site in Southern China and Enantioselective Biotransformation of Chiral PCBs in Plants
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中国南方电子垃圾场植物、空气和土壤中多氯联苯含量升高及手性多氯联苯在植物中的对映选择性生物转化
DOI：
10.1021/es405632v
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发表时间：
2014-04-01
影响因子：
11.4
通讯作者：
Mai, Bi-Xian
中科院分区：
文献类型：
--
作者：
Chen, She-Jun;Tian, Mi;Mai, Bi-Xian
含有多氯联苯（PCB）的电子废物跨越国界，通常从北方半球的工业化国家（以前使用这些物品）转移到东南亚和非洲的亚热带和热带地区。因此，由于这些低纬度地区的气温升高，多氯联苯很有可能从主要来源释放到环境中。在本研究中，多氯联苯和手性多氯联苯（PCB 84，95，132，136，149和183）的对映体馏分（EF）进行了分析，空气中，桉树叶，松针，土壤中的电子废物网站和农村网站在中国南方。在电子废物现场的多氯联苯浓度范围从7825至76330皮克/立方米（3），27.5至1993纳克/克，24.2至12045纳克/克的空气（气体加颗粒），植物叶片和土壤，分别。大气中多氯联苯的组成分布表明，五氯联苯和六氯联苯的丰度相对较高，这与以前在中国各地的空气中观察到的不同。Clausius-Clapeyron回归分析表明，当地受污染表面的蒸发是电子废物场地空气中多氯联苯的主要排放源。除了多氯联苯84（0.420 +/- 0.050）外，电子废物场地空气中多氯联苯的手性特征基本上是外消旋的（气相中平均EF =（0.484 +/- 0.022）-（0.499 +/- 0.004）），这表明外消旋来源在空气中多氯联苯排放中占主导地位。土壤中的多氯联苯手性特征（（0.422 +/- 0.038）-（0.515 +/- 0.016））与空气中的特征相似，但多氯联苯95除外。然而，与空气和土壤中的手性PCBs相比，植物（特别是桉树叶）中的手性PCBs具有显著的非外消旋残留（（0.368 +/- 0.075）-（0.561 +/- 0.045））。这一发现表明，这些阻转异构体的多氯联苯的对映体选择性生物转化很可能发生在植物叶片中，可能是由于代谢细胞色素P-450酶在叶片中。据我们所知，这是第一个报告的对映体选择性代谢的手性多氯联苯在植物在田间条件下。
E-waste that contains polychlorinated biphenyls (PCBs) is moved across national boundaries, often from industrialized countries in the northern hemisphere, where the items were formerly used, to subtropical and tropical regions in southeastern Asia and Africa. As a result, there is a high likelihood that PCBs will be released into the environment from a primary source due to the elevated temperatures encountered in these low-latitude regions. In the present study, PCBs and enantiomer fractions (EFs) of chiral PCBs (PCB 84, 95, 132, 136, 149, and 183) were analyzed in air, eucalyptus leaves, pine needles, and soil at an e-waste site and a rural site in southern China. The concentrations of PCBs at the e-waste site ranged from 7825 to 76330 pg/m(3), 27.5 to 1993 ng/g, and 24.2 to 12045 ng/g in the air (gas plus particle), plant leaves, and soils, respectively. The atmospheric PCB composition profiles in the present study indicated relatively high abundances of penta- and hexa-PCBs, which were different from those previously observed in the air across China. The Clausius-Clapeyron regression analysis indicated that evaporation from local contaminated surfaces constitutes a primary emission source of PCBs in the air at the e-waste site. The chiral signatures of PCBs in the air at the e-waste site were essentially racemic (mean EFs = (0.484 +/- 0.022)-(0.499 +/- 0.004) in the gaseous phase) except for PCB 84 (0.420 +/- 0.050), indicating that racemic sources dominate the PCB emission in the air. PCB chiral signatures in the soils ((0.422 +/- 0.038)-(0.515 +/- 0.016)) were similar to those in the air except for PCB 95. However, the chiral PCBs in the plants (especially the eucalyptus leaves) had significantly nonracemic residues ((0.368 +/- 0.075)-(0.561 +/- 0.045)) compared to those in the air and soil. This finding suggests that enantioselective biotransformation of these atropisomeric PCBs was very likely to occur in the plant leaves, possibly due to metabolism by cytochrome P-450 enzymes in leaves. To our knowledge, this is the first report on the enantioselective metabolism of chiral PCBs in plants under field conditions.