Organochlorine pesticides in fresh-fallen snow on East Rongbuk Glacier of Mt. Qomolangma (Everest)

摘要

During a field campaign in April 2005, fresh-fallen snow samples were collected on the East Rongbuk Glacier of the Mt. Qomolangma at four altitudes (6500 m, 6300 m, 6100 m and 5900 m), to study the role of Mt. Qomolangma as "cold-traps" for Persistent Organic Pollutants. From these snow samples collected at the highest-altitude, organochlorine pesticides (OCPs):HCB, p,p'-DDT and p, p'-DDD were detected, with the concentrations in the ranges of 44—72 pg/L, 401—1560 pg/L, and 20—80 pg/L, respectively. The concentration of o, p -DDT was around the method detection limit. Analysis of backward trajectories showed that the detected compounds came from the north of India, suggesting that DDTs detected in the snow were possibly originated from new emissions in this area. Relationships between the concentrations of OCPs in snow samples and the sampling altitudes were discussed. The altitudes had no obvious effect on HCB concentrations in the fresh-fallen snow, while increases in the concentrations of p,p'-DDT and p, p'-DDD with increasing altitude were found, which was reversed compared to the trends observed in North America. Three factors likely resulted in this trend: (1) the properties of the target compounds; (2) the low temperatures at high altitudes; and (3) the location of the mountain sampling sites relative to their sources.