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

Wenying Meng,Peijie Zuo,Qinghua Zhang,Huizhong Sun,Ruiqiang Yang,Dou Wang,Guibin Jiang,Pu Wang,Julius Matsiko,Yingming Li

doi:10.1038/s41598-018-32093-y

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.

Highlights

The Tibetan Plateau (TP), located in the eastern Eurasian continent, is the largest and highest plateau in the world
Wang et al.[22] investigated the distribution profiles of organochlorine pesticides (OCPs) and PCBs in the forest soil and found that there was no difference on both sides of this mountain
There was no significant difference observed between the total organic carbon (TOC) values on both the sides (p > 0.05)

Summary

Introduction

The Tibetan Plateau (TP), located in the eastern Eurasian continent, is the largest and highest plateau in the world. Compared with the western and northern TP regions, the altitude of the southeastern TP is generally lower It is characterized by mountain-valley topography and is one of the main forest regions of the plateau due to the www.nature.com/scientificreports/. Mt. Sygera lies in the southeastern TP and is characterized by the windward and leeward side, which makes it an ideal setting for studies on LRAT of POPs. Previously, Wang et al.[22] investigated the distribution profiles of organochlorine pesticides (OCPs) and PCBs in the forest soil and found that there was no difference on both sides of this mountain. Zhu et al.[23] investigated the altitudinal distribution of PCBs and PBDEs in air along different slopes of Mt. Sygera in 2015 and found out that the POP concentrations had no obvious variation on the windward side but observed a decreasing trend on the leeward side along the altitude.

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