Tracking Persistent Organic Pollutants in the pristine "Environment of the Mountainous Ranges of Northern Pakistan: The Implication for Long Range Atmospheric Transport and Mountain Cold Trapping along Altitudinal Gradient

Abstract

Higb a ltitude mOUlllain regions are ideal settings [0 study fate and behavior of Persistent Organic Pollutants (POPs). The pristine region of the mountainous ranges of northern Pakistan is characterized by mountain valley topography and di verse climatic conditions. POPs can be transferred to this region through Long Range Atmospheric Transp0l1 (LRAl) from the adjacent densely populated and agricultural countries li ke India, Ch.ina and Sothern pari of Pakistan. To investigale the signature and implications for LRAT and cold trapping effect a long altitude soil and sedime,nt samples were analyzed. Overall detection level of POPs were quite low but were comparable with the background concentrations reponed from the variolLs studies around the globe. The general trend of POPs was In this order OCPs>PCBs>PBDEs>NBFRs with average mean concentration of 2.150±J.326. O.544±O.529, O.417± 1.455and O. 149±O.185 nglg respectively. Among OCPs. DOTs were the Illost abundam in the study with an average concentration of 1.77 nglg followed by Endosulfan and HCH. Hexa and Tetra CBs were more preva lent among PCBs and BDE-209 was more frequent congener found among PBDEs. While NBFRs were detected at very low levels. No significant correjation was found for the concentration of POPs with increasing altitllde but steady trend was observed from low to mid altitudes under study. High ratios of DDTIDDE+ODD and low ratio of aIy-HCH indicated the use of dicofol and Lindane in the adjacent countries. Low ratio of aI,B-Endosulfan indicates the absence ofteclmical Endosul fan and Im-\l TCICe ratio suggests the hint of aged chlordane. The air mass back traj ectory analysis revea led that the sampling area is mainly ,influenced by the air currents from North India, Chhla and South part of Pakistan, So it can be assumed that these contaminants have been transported to the area by atmospheric transport from source regions. FUl1her research need to be do ne to unde rstand the environmental complexities assoc iated with long range transport and cold trapping phenomena of POPs.