Soil concentrations, occurrence, sources and estimation of air–soil exchange of polychlorinated biphenyls in Indian cities

Paromita Chakraborty, Gan Zhang, Jun Li, Sakthivel Selvaraj, Knut Breivik, Kevin C. Jones
2016 Science of the Total Environment  
Past studies have shown potentially increasing levels of polychlorinated biphenyls 21 (PCBs) in the Indian environment. This is the first attempt to investigate the occurrence of PCBs 22 in surface soil and estimate diffusive air-soil exchange, both on a regional scale as well as at local 23 level within the metropolitan environment of India. From the north, New Delhi and Agra, east, 24 Kolkata, west, Mumbai and Goa and Chennai and Bangalore in the southern India were selected 25 for this
more » ... 33 PCB congeners were quantified in surface soil and possible sources were derived 26 using positive matrix factorization model. Net flux directions of PCBs were estimated in seven 27 major metropolitan cities of India along urban-suburban-rural transects. Mean Σ33PCBs 28 concentration in soil (12 ng/g dry weight) was nearly twice the concentration found in global 29 background soil, but in line with findings from Pakistan and urban sites of China. Higher 30 abundance of the heavier congeners (6CB-8CB) was prevalent mostly in the urban centers. Cities 31 like Chennai, Mumbai and Kolkata with evidence of ongoing PCB sources did not show significant 32 correlation with soil organic carbon (SOC). This study provides evidence that soil is acting as sink 33 for heavy weight PCB congeners and source for lighter congeners. Atmospheric transport is 34 presumably a controlling factor for occurrence of PCBs in less polluted sites of India. 35 36 37
doi:10.1016/j.scitotenv.2016.03.009 pmid:27136304 fatcat:psqtxkabz5fkxgk6r7bbjxqmym