Altitudinal dependence of PCBs and PBDEs in soil along the two sides of Mt. Sygera, southeastern Tibetan Plateau

Abstract

Surface soil samples were collected from Mt. Sygera in the southeast of Tibetan Plateau to investigate the altitudinal distribution of PCBs and PBDEs along the two sides of the mountain. The average concentrations of PCBs and PBDEs were 177 pg g−1 dw and 15 pg g−1 dw, respectively. The relationships between the log-transformed TOC-normalized concentrations and the altitudes showed different trends on the two sides. On the windward side, there was a positive correlation for the heavier PCBs; while on the leeward side, the concentrations increased and then decreased for PCBs and PBDEs at the altitude of 4100–4200 m, corresponding to the change in vegetation. The observed discrepancy on the two sides of the mountain demonstrated different key factors associated with precipitation and the forest canopy. Additionally, values of windward-leeward Enrichment Factors (W/L EFs) for the heavier PCB congeners (PCB-138, 153, and -180) were an order of magnitude higher in sites above 4200 m, which also suggested that vegetation played an important role in the altitudinal accumulation of POPs in soil. This is one of the very few studies that have revealed the differences in altitudinal accumulation of POPs along the two sides of a mountain.

Persistent organic pollutants in global surface soils: Distributions and fractionations

“…Numerous studies have been carried out following the work by Blais and co-workers, such as studies in the surface soil for PAHs [ 80 ], PCBs and OCPs [ 81 ], PCBs and selected OCPs [ 82 , 83 ], PCBs and PBDEs [ [84] , [85] , [86] ], and OCPs in the soil [ 55 , 73 , [87] , [88] , [89] ]. Five studies investigated PCBs in surface soils within the Qingzang Plateau, China [ 82 , [84] , [85] , [86] , 90 ]. In addition to the aforementioned findings, several studies have investigated the presence of various pollutants in different media.…”

“…The forest filter effect was identified as a potential explanation for this variation. In another study, Meng and co-workers [ 86 ] studied the altitudinal distribution of PCBs and PBDEs in the surface soil samples collected along two sides of Mt. Sygera, southeast of the Qingzang Plateau.…”