SRM Research Institute and Department of Civil Engineering, SRM University, Kattankulathur, Tamil Nadu, India.
State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
Sci Total Environ. 2016 Aug 15;562:928-934. doi: 10.1016/j.scitotenv.2016.03.009. Epub 2016 Apr 29.
Past studies have shown potentially increasing levels of polychlorinated biphenyls (PCBs) in the Indian environment. This is the first attempt to investigate the occurrence of PCBs in surface soil and estimate diffusive air-soil exchange, both on a regional scale as well as at local level within the metropolitan environment of India. From the north, New Delhi and Agra, east, Kolkata, west, Mumbai and Goa and Chennai and Bangalore in the southern India were selected for this study. 33 PCB congeners were quantified in surface soil and possible sources were derived using positive matrix factorization model. Net flux directions of PCBs were estimated in seven major metropolitan cities of India along urban-suburban-rural transects. Mean Σ33PCBs concentration in soil (12ng/g dry weight) was nearly twice the concentration found in global background soil, but in line with findings from Pakistan and urban sites of China. Higher abundance of the heavier congeners (6CB-8CB) was prevalent mostly in the urban centers. Cities like Chennai, Mumbai and Kolkata with evidence of ongoing PCB sources did not show significant correlation with soil organic carbon (SOC). This study provides evidence that soil is acting as sink for heavy weight PCB congeners and source for lighter congeners. Atmospheric transport is presumably a controlling factor for occurrence of PCBs in less polluted sites of India.
过去的研究表明，印度环境中的多氯联苯（PCBs）含量可能在不断增加。本研究首次尝试调查印度大都市环境中表层土壤中 PCBs 的存在情况，并估算其在区域和局部范围内的扩散型气-土交换通量。为此，我们选择了印度北部的新德里和阿格拉、东部的加尔各答、西部的孟买和果阿以及南部的钦奈和班加罗尔进行研究。本研究共定量分析了 33 种 PCBs 同系物，并利用正定矩阵因子模型来推断其可能的来源。我们沿着城市-郊区-农村的梯度，在印度七个主要的大都市区估算了 PCBs 的净通量方向。土壤中Σ33PCBs 的平均浓度（干重 12ng/g）几乎是全球背景土壤中浓度的两倍，但与巴基斯坦和中国城市地区的发现一致。在城市中心，更重的同系物（6CB-8CB）的丰度更高。在钦奈、孟买和加尔各答等存在持续 PCB 源证据的城市，其土壤有机碳（SOC）与 PCBs 浓度之间没有显著相关性。本研究表明，土壤是重质 PCBs 同系物的汇，也是轻质同系物的源。大气传输可能是控制印度污染较轻地区 PCBs 存在的因素。
