Content Analysis Of Heavy Metals In Surface Sediment And Health Risk Assessment Of Household Water In The Lhasa River Basin

The Lhasa River basin is the political,economic and cultural center of Tibet autonomous region and has abundant resources.Some problems such as inconvenient accessibility and insufficient energy supply were gradually being solved.With the economic growth in the Lhasa River basin,which creating favorable conditions for the development of watershed resources as well as bringing potential pollution risks to the ecological environment.Our research group has found that there was a risk of Hg,As and Cu pollution in surface water in the Lhasa River Basin.Based on the existing risk assessment of heavy metal pollution in the surface water of the Lhasa River,the subject takes the surface sediments and household water of the Lhasa River Basin as the research object.Mathematical calculations and source apportionment technology had been used to systematic analyzed the status of heavy metal pollution and the health risks for residents in the Lhasa River Basin.This research evaluated the heavy metal pollution in the Lhasa River Basin from the aspects of bio-toxicity,potential risk,pollution distribution and human activities on the heavy metals in sediments by using sediment quality guidelines,geo-accumulation index,potential ecological risk index and pollution load index respectively.The comprehensive evaluation results showed that the Lhasa River Basin was in a state of no pollution or slight pollution,and there was a risk of contamination of Cd,Cu,As,Pb in some areas.Principal component analysis,positive matrix factorization and cluster analysis method were used to analyze the source of heavy metal pollution in Lhasa River Basin.The comprehensive results obtained by the three source analysis methods showed that the source of heavy metal pollution in the Lhasa River Basin can be divided into three categories: mining development,human activities and natural process.This research analyzed the water quality of household water in 286 families in the Lhasa River Basin based on the drinking water guidelines.The results showed that there were only 7 household water samples with heavy metal concentrations exceeding the standard and the super standard elements were Zn and As.The compliance rate of heavy metal content test results for household water in the Lhasa River Basin can reach 99%.Overall,the water quality of household water was good.While the health risk assessment model was applied to assess the health risks of household water,the results showed that the health risks of household water in the Lhasa River Basin were mainly determined by drinking water ingestion pathway.Among the households surveyed,there were 11 households with moderate to high health risks,and relatively high levels of Cr and As were the factors for the high level of health risk.