| Integrated Biomarker Response(IBR)based ecological risk assessment can sensitively reflect the potential negative influence of contaminants on the organisms and ecosystem,so that can provide the early warning of seriously hazard of pollutants.However,there are still some drawbacks in IBR,which greatly influence their application in the aquatic ecological risk assessment.The present study determined the contents of several pollutants in the surface water and fish body(Carassius auratus)collect from Dianchi Lake,as well as the pollutants-related response of biomarkers expression,by combining the active biomonitoring and passive biomonitoring measurements.The spatial and temporal distribution of pollutants in the fish body of Dianchi Lake and their bioaccumulation were analyzed.The "dose-effect" relationship between biomarkers’ expression level in fish body and the total nitrogen(TN),total phosphorus(TP),heavy metals and organic pollutants were explored,respectively,and a new index system for integrated biomarker was established.According to this index system,we comprehensively evaluated the aquatic ecological risk in Dianchi Lake based on the optimized IBR,and discussed the potential applications of IBR in the ecological risk assessment.Main results are listed as follows:(1)The water eutrophication in Dianchi Lake remained fairly serious.The contents of TN,TP in the surface water of 5 sampling sites are all beyond class V of the National Surface Water Standard.The spatial distribution pattern of TN,TP is lower from north to south showing a significant difference.The contents of TN,TP in the surface water in the Caohai(north of Dianchi Lake)is the highest,which up to 6.51 ±0.49 mg/L and 0.137±0.013 mg/L,respectively.The contents of mercury(Hg)is the highest levels in the southeast of Dianchi Lake,can be up to 1.01 ±0.24 μg/L,which meets the national surface water V class standard,whereas the contents of copper(Cu),arsenic(As),cadmium(Cd)and lead(Pb)in Dianchi lake are lower.No organic pollutants(i.e.Dichlorodiphenyltrichloroethane,Hexachlorocyclohexane,and Methylbenzene)were detected in the surface water of Dianchi Lake.(2)In active biomonitoring experiment,body metal contents of Cu,As,Cd,Pb and Hg are all low in muscles,whereas the bioaccumulation of Pb in fish muscle is significant.At passive biomonitoring,the biological concentration factor of Pb is 172 in Caohai,98 in Waihai,a litter bit lower than the contents of Cu,a biological necessary elementary in the fish body.There is no significant bioaccumulation effect of the organic pollutants,including DDT,HCH,and PhMe.(3)Along with the spatial and temporal distribution of pollutants in the surface water and muscles of fish body,the expression level of biomarkers displayed either induction effect or inhibition effect at active biomonitoring.In contrast,the biomarkers expression at passive biomonitoring appeared a certain extent passivation.There are 6 biomarkers which are sensitive response to contaminants,were recommended to compose a new index system for ecological risk assessment in Dianchi Lake.They are glutathione peroxidase(GPx),Na+/K+ adenosine triphosphatase(Na+/K+-ATPase),superoxide dismutase(SOD),malondialdehyde(MDA),metallothionein(MT)and acetylcholinesterase(AChE),respectively.(4)According to the period of active biomonitoring,IBR can effectively reflect the ecological risk of different pollutants in Dianchi Lake.At 7 days in active biolmonitoring,IBR evaluation results reveal the water eutrophication degree is higher in the northeast of Dianchi Lake,and the contents of TN are the main contributors in the surface water.At 14 days in active biomonitoring,IBR evaluation results reflect the highest potential ecological risk of heavy metals in the west bank of Dianchi Lake,and the main contributors are Pb and Cd.(5)IBR can effectively reflect the different aqua-ecological risks in Dianchi Lake,and reveal different levels of biomarker response in fish body to a variety of pollutants,which shows a great promise for potential application in ecological risk assessment in Dianchi Lake. |
