EVALUATION ON THE STATUS QUO OF WATER ENVIRONMENTAL FOR THE UPPER AND MIDDLE REACHES OF THE YARLUNG ZANGBO RIVER IN THE LOW WATER PERIOD

Water samples at 12 sampling sites in the upper and middle reaches of the Yarlung Zangbo River were collected; water quality indexes such as permanganate index, total phosphorus, petroleum, total nitrogen, ammonia nitrogen and heavy metal, etc. were detected; influence factors such as population density and river discharge, etc. in the upper and middle reaches of the Yarlung Zangbo River were combined to analyze the correlation between human activities and runoff rate & water quality. Results showed that sampling sites 6 and 7 close to Lhasa, with the largest density of population in Tibet, had both the highest content of ammonia nitrogen and total nitrogen in the water body of the Yarlung Zangbo River. Heavy metal elements such as Cu, Zn and Cr had a higher content in the densely populated areas. Content of nickel (Ni), zinc (Zn), arsenic (As), aluminum (Al), vanadium (V), manganese (Mn), ferrum (Fe), barium (Ba) and lead (Pb) was greatly affected by river runoff. Organic pollutants such as PCB, PAH, organochlorine pesticide, plasticizer, etc. were not detected at all sampling sites.