ORIGINAL ARTICLE Distribution and risk assessment of polychlorinated biphenyls (PCBs) in the remote air and soil of Manipur, India Ningombam Linthoingambi Devi • Ishwar Chandra Yadav • Qi Shihua • Paromita Chakraborty • Yang Dan Received: 9 July 2013 / Accepted: 12 April 2014 Ó Springer-Verlag Berlin Heidelberg 2014 Abstract P 25 PCB congeners including dioxin-like compounds were analyzed at three sites of Manipur India to assess the level of polychlorinated biphenyls (PCBs) in air and soil. The P 25 PCBs were higher in urban air (average 2,454 pg/m 3 ), followed by the mountain air (average 2,109 pg/m 3 ) and rural air (average 1,756 pg/m 3 ). PCB levels observed in urban air were higher compared to PCB levels reported in major Indian metropolitan cities especially along the coastal region and were comparable with the pristine sites of India and also with some pockets of China and Europe. The heavier congeners (tetra, penta, tri and hexa) were dominant in both air and soil samples and show significant correlation with the ambient temper- ature. Emission of PCB congeners was investigated from soil surface. The total organic carbon present in soil shows the significant correlation (r 2 = 0.8; p \ 0.05) with the PCBs could indicate that the PCBs originated from the similar sources. Principal component analysis revealed that the sources of higher chlorinated PCB congeners are local emissions while long-range atmospheric transport process is responsible behind elevated levels of lower chlorinated PCBs. Total calculated toxic equivalent (TEQ) levels in soil (37.17–160.5 pg/g) were superior to reported TEQ level of agricultural soil in Delhi, India (0.01–105.40 pg/g). Back trajectory analysis showed that the observed high levels of PCB at Manipur may due to movement of air masses, mostly from the Northern and Southern India and to some extent from Myanmar. Keywords Polychlorinated biphenyls  Toxicity equivalent  Principal component analysis  Back trajectory analysis  Manipur Introduction In recent decades, there has been increasing interest on polychlorinated biphenyl compounds (PCBs) because of their high toxicity, persistence and carcinogenic/mutagenic human health effects. Because of lengthy half-life time of PCBs, they are capable of long-range atmospheric transport (AMAP 2004). They may enter the atmosphere from vari- ous sources such as transformers, incinerators, landfills, sludge drying beds, soil or air–water exchange (Hsu et al. 2003). Persistency and toxicity of the PCB congeners depend on their physicochemical characteristics such as number and position of chlorine atoms, its molecular weight, vapor pressure and half-life time (Carpenter 2006). Lighter PCB congeners exist in gaseous phase while heavier congeners are absorbed to the aerosols (Eckhard et al. 2007; Webster et al. 1998). Lighter PCB congeners can move faster from one place to other, get degraded sooner and disperse more readily than their heavier counterpart. These congeners may also undergo a reversible atmospheric deposition with soil and water surface through an exchange process (Wania and Mackey 1993). This air–soil exchange (grass hopping) process leads to global fractionation (Wania N. L. Devi  Q. Shihua  Y. Dan State Key Laboratory of Biogeology and Environmental Geology, School of Environmental Studies, China University of Geosciences, Wuhan 430074, China e-mail: n.linthoi.devi@gmail.com N. L. Devi Centre for Environmental Sciences, Central University of Bihar, BIT Campus, P.O.-B. V. College, Patna 800 014, India I. C. Yadav (&)  P. Chakraborty SRM Research Institute, SRM University, Kattankulathur, Tamil Nadu 603203, India e-mail: icyadav.bhu@gmail.com 123 Environ Earth Sci DOI 10.1007/s12665-014-3284-8