The Ecological Risk Assessment Of Chromium In Taihu Lake

Taihu lake is the third largest freshwater lake in China.The lake plays an important role in surrounding areas thro?gh water supply and irrigation navigation.With economic development and population growth,Taihu lake problems have caused wide spread concern.In recent years,heavy metal pollution has aroused extensive attention.Chromium is the accumulation of toxicant and carcinogenic heavy metal.This study makes comprehensive in-depth analysis and checks the concentration of Chromium(Cr)from Taihu water,fish and sediment.The results indicate as follows.(1)Atomic absorption spectrophotometry(AAS)which was based on this study for the total quantity and configuration of Chromium can basically content the needs of accuracy and precision that experimental analysis and determination require.The samples were pretreated by wet digestion method.The recovery rate was between 80%and 120%,the limit of detection was 1.4498±1.8554 pg/kg.Each sample should be two times parallel test and the instrument automatically deducted from the reagent blank.The relative standard deviation(RSD)was less than 10%,which indicated that the method could measure chromium with high precision.(2)There were 30 surface water samples collected from ten lake districts(Daleishan,Dapu,Gonghu Bay,Hengshan,Science Lab,Manshan,Pingtaishan,Tanglou,Changdou Harbor,Zhushan Bay)in June 2014.The exposure concentration of Cr in water ranged from 7.3 ?g/L to 10.3 ?g/L,in line with the surface water quality standards for Class I standard.On the basis of the toxic effect of existing data,the safe concentration of Chromium in fresh water was 1.26 ?g/L.The exposure concentration was far higher than the safe concentration,Cr in Taihu lake had produced definite ecological risk to the aquatic organisms.(3)This survey collected 401 fish samples,consisted of 315 omnivorous-samples,49 carnivorous-samples and 37 herbivorous-samples,which belonged to 22 species from eleven lake districts on April to June 2014.The results showed that Cr content ranged from ND(none detection)to 5.21 mg/kg.There were 12 samples in heavy pollution levels.The content of Cr in omnivorous fish were significantly higher than that of herbivorous fish,but it showed no correlation with that of carnivorous fish.This may be related to the living environment of fish.The assessment results showed that the concentration of Cr went beyond the provisional tolerable weekly intake(PTWI)for 7.48%which indicated that the intake of fish in Taihu Lake may be harmful to human health.(4)Gathered 30 copies of sediment samples with the place where we collected water samples.The test showed that the concentrate of Cr in sediment between 14 mg/kg and 36 mg/kg,lower than the background value(90 mg/kg),which belonged to level ? in the environment.Distribution characteristic of Cr in sediment was the content of north higher than thing ministry,which may be closely related to the topography and the surrounding industrial.In summary,this experiment by Taihu lake as the study area,analyzed the content and distribution of Cr,assessed the ecological risk and dietary risk.This survey was helpful to further understand the pollution of Cr in Taihu lake and provided reference to the quality and security of aquatic products in Taihu lake.