Study Of Persistent Organic Pollutants (POPs) On Mt. Qomolangma

High mountains may serve as condenser for persistent organic pollutants (POPs). Tibetan Plateau locates in the low-middle latitude and high attitude region. It's a huge high-mountain area with the average elevation above 4000m and the thickest lithosphere of the world. Tibetan Plateau is pristine because of its few industrial and agricultural activities. However, there are anthropogenic activities around the area. Because the influence of the southern Asian monsoon and westerly airflow, Tibetan Plateau is affected by the air mass transport originated from Indian subcontinent and Europe-Asia continent. On one hand, Tibetan Plateau plays an important role on the global transport of POPs, on the other hand, Tibetan Plateau suffers heavy threat of pollutants.The ice, snow, soil and vegetation in remote areas has been used as a means to characterize atmospheric concentrations of air pollutants. Solid phase microextraction, soxhlet extraction, ultrasonic extraction and ion trap tandem mass spectrometric method (GC-MS/MS) were used in this study. The operation parameters of these techniques were optimized. The more sensitive method for determination of trace organochlorine pesticides (OCPs) and polycyclic aromatic hydrocarbons (PAHs) in samples were developed. We investigated the concentrations of POPs in snow, soil and vegetation samples from Mt. Qomolangma (central Himalayas) and studied theconcentration of POPs alonge the elevation gradient and the possible pollution sources in this region.The observed results showed that in the snowpit samples from 6530 m (a s 1.) in Mt. Qomolangma region, the heavy PAHs (Bbf, Bap, InPyr and Bgihp) were observed only in the layer of 85-102cm. Whereas the lighter PAHs were the main pollutants in other snow layers. The concentration of PAHs in snow was closely related to the particles deposited in it. The higher the particle concentration, the higher the POPs . The concentrations of PAHs show seasonal variation, and high values of PAHs were observed in winter as compared to summer. Only DDTs were detected in soil samples. Unlike the soil samples, grass samples showed the presence of other OCPs, including HCHs, HCB, and endosulfans Our measurements of HCH and DDT in grass samples show the same concentration levels or slightly higher than reported in moss from Mt. Qomolangma 15 years ago. This result and the analysis of isomer ratios (which depend on degradation rates) indicate recent releases of OCPs from a nearby region, possibly from dicofol use in India.The volatile OCPs were progressively concentrated in colder and higher elevation sites. Bioconcentrated factor (BCF) of grass was calculated and the BCF values increased with the increasing of elevation, indicating that the cold condensation of POPs at high elevation sites may increase the potential menace to vegetation and food chain in mountain ecosystem.Total HCHs and DDTs concentration in pine needle samples fromZhangmu-Nyalam region (central Himalayas) were in the range of 1.36-2.99 ng g'1 dry weight and 1.71-11.9 ng g"1 dry weight. Total pine needle PAHs was below 600 ng g'1 and fluorene, phenanthrene and acenaphthene were abundant individual compounds measured. Almost all PAHs detected in this area showed positive correlations with altitude. The ratios of a-HCH /y-HCH implyed technical HCHs might be used in this region. The high ratios of o-p'-DDT / p-p'-DDT and no p-p'-DDE measured in this study led to the suspicion that a new source of o-p'-DDT and /or p-p'-DDT existed in this region. In addition, higher ratios of low molecular weight-/ high molecular weight-PAHs in this region indicated that petroleum combustion, vehicle emission and low-temperature combustion might be the major contributions of PAHs sources.