Forest canopy can accumulate persistent organic pollutants (POPs) from the atmosphere and further supply them into soil and terrestrial food webs by litter fall. Forest soil is therefore traditionally considered as a sink for POPs. With global warming, however, it is likely to become a secondary source for POPs. The air-soil and air-forest canopy exchange of POPs is key to understanding regional and even global cycling of pollutants.

 

Under the auspices of NSFC project titled Role of Southeast Tibetan Forest in Air Surface Exchange of Organochlorine Pollutant and its Biosecurity Effect, ITP scientific staff initiated a continuous sampling project in the southeast Tibet forest from May, 2011. Leaves of 13 different plants at various elevations have continuously been sampled in southeast Tibet, where passive air samplers were widely distributed. Boxes have also been placed in the forest for litter collection at respectively, 2500m, 3300 m, 4200 m, and 4400 m-elevated sites. Besides, seven vertical profiles have been chosen to study the vertical gradient of POPs.

 

This research project tends to evaluate the air-soil and air-canopy exchange fluxes in the southeast Plateau, quantify the POPs storage in regional forest system, thus to understand the biosecurity effect of southeast Tibetan forest. It is also believed that the results will provide numerical and theoretical bases for biosecurity assessment and construction in the southeast Tibetan plateau.