Forest filter effect versus cold trapping effect on the altitudinal distribution of PCBs: a case study of Mt. Gongga, eastern Tibetan Plateau.
Mountains are observed to preferentially accumulate persistent organic pollutants (POPs) at higher altitude due to the cold condensation effect. Forest soils characterized by high organic carbon are important for terrestrial storage of POPs. To investigate the dominant factor controlling the altitudinal distribution of POPs in mountainous areas, we measured concentrations of polychlorinated biphenyls (PCBs) in different environmental matrices (soil, moss, and air) from nine elevations on the eastern slope of Mt. Gongga, the highest mountain in Sichuan Province on the Tibetan Plateau. The concentrations of 24 measured PCBs ranged from 41 to 510 pg/g dry weight (dw) (mean: 260 pg/g dw) in the O-horizon soil, 280 to 1200 pg/g dw (mean: 740 pg/g dw) in moss, and 33 to 60 pg/m(3) (mean: 47 pg/m(3)) in air. Soil organic carbon was a key determinant explaining 75% of the variation in concentration along the altitudinal gradient. Across all of the sampling sites, the average contribution of the forest filter effect (FFE) was greater than that of the mountain cold trapping effect based on principal components analysis and multiple linear regression. Our results deviate from the thermodynamic theory involving cold condensation at high altitudes of mountain areas and highlight the importance of the FFE.
State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences , Guangzhou 510640, China.
Xin
X
Liu
Jun
J
Li
Qian
Q
Zheng
Haijian
H
Bing
Ruijie
R
Zhang
Yan
Y
Wang
Chunling
C
Luo
Xiang
X
Liu
Yanhong
Y
Wu
Suhong
S
Pan
Gan
G
Zhang
D000393:Air Pollutants / Q000032:analysis*; D000531:Altitude; D044002:Bryophyta / Q000737:chemistry*; D003080:Cold Temperature; D004784:Environmental Monitoring; D065928:Forests; D011078:Polychlorinated Biphenyls / Q000032:analysis*; D012989:Soil Pollutants / Q000032:analysis*; D018609:Tibet
D000393:Air Pollutants; D012989:Soil Pollutants; D011078:Polychlorinated Biphenyls