Spatial distribution of the persistent organic pollutants across the Tibetan Plateau and its linkage with the climate systems: a 5-year air monitoring study
The Tibetan Plateau (TP) has been contaminated by persistent organic pollutants (POPs), including legacy organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) through atmospheric transport. The exact source regions, transport pathways and time trends of POPs to the TP are not wel...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-06-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/16/6901/2016/acp-16-6901-2016.pdf |
| Summary: | The Tibetan Plateau (TP) has been contaminated by
persistent organic pollutants (POPs), including legacy organochlorine
pesticides (OCPs) and polychlorinated biphenyls (PCBs) through atmospheric
transport. The exact source regions, transport pathways and time trends of
POPs to the TP are not well understood. Here polystyrene–divinylbenzene
copolymer resin (XAD)-based passive air samplers
(PASs) were deployed at 16 Tibetan background sites from 2007 to 2012 to gain
further insight into spatial patterns and temporal trends of OCPs and PCBs.
The southeastern TP was characterized by dichlorodiphenyltrichloroethane
(DDT)-related chemicals delivered by Indian monsoon air masses. The
northern and northwestern TP displayed the greatest absolute concentration
and relative abundance of hexachlorobenzene (HCB) in the atmosphere, caused
by the westerly-driven European air masses. The interactions between the DDT
polluted Indian monsoon air and the clean westerly winds formed a transition
zone in central Tibet, where both DDT and HCB were the dominant chemicals.
Based on 5 years of continuous sampling, our data indicated declining
concentrations of HCB and hexachlorocyclohexanes (HCHs) across the Tibetan
region. Inter-annual trends of DDT class chemicals, however, showed less
variation during this 5-year sampling period, which may be due to the
ongoing usage of DDT in India. This paper demonstrates the possibility of
using POP fingerprints to investigate the climate interactions and the
validity of using PAS to derive inter-annual atmospheric POP time trends. |
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| ISSN: | 1680-7316 1680-7324 |