Present Situation Of Water Pollution And Health Risk Assessment In Yulin City

Yulin is located in arid and semi-arid areas,where water resources are scarce and their distribution is uneven,resulting into the fragile ecological environment.The amount of water supply is insufficient and the utilization of natural water resources is not ideal.Hongshixia district in Yulin is one of the earliest built reservoirs,which also takes the responsibility of water supply nearly 70%,guaranteeing the local economic development and people's health.Therefore,this ariticle takes Hongshixia district as an example,selecting 7 ground water and 14 surface water sampling sites.Water pollution is analyzed via AHP and Fuzzy evaluation models;Its health risk is calculated by combing Monte Carlo simulation and "four step"strategy.The relevant progress and results are as follows:(1)The main pollutants in the groundwater of Hongshixia district were cadmium,volatile phenol and mercury.The main factors of surface water was DO,followed by fluoride and ammonia,but heavy metals had little effect.Combining with Fuzzy evaluation,it was revealed that the quality of groundwater is well,which generally ranked in the class I to II,while the spots of polluted surface water in this district were relatively dispersed,and most of their quality ranked in class ? to ?,some of which spots ranked even class IV to V.(2)The rank of risk to human health for each pollutant was:As>Cr6+>Cd>fluoride>Pb>Hg>ammonia nitrogen>cyanide>volatile phenol.The health risk to human when exposed to surface water and groundwater were mainly caused by cancerogen(As,Cd,Cr6+),indicating that its water quality did have impact on people's health;Besides,the health risk rate caused by drinking water's carcinogen Cr6+ was relatively high,even worse than the situation in natural water of Hongshixia,and this condition kept no change since 2008;The non-carcinogenic mercury rapidly declined from 2009-2012,but in the last two years it returned back;Which meant the pollution of Cr6+ and Hg were affected by the transportation of drinking water.In contrast,the health risk caused by other pollutants were fairly low.(3)In Hongshixia district,water quality turned better first but worse then,according to its flow direction.It was investigated that there were some factories around the upstream,then waste gas,waste water and waste residue would enter into the natural circulation without proper treatment.The water quality in middle distrcit was good due to the existence of isolated fence and water treatment facilities,the surrounding pollution source being less too;The water finally flowed down to the village and city,but different kinds of wastes produced by human being lead to water pollution.The highway transportation accelerated the deterioration of the water body.So,It is imperative to strengthen the management of watershed and water supply process...