| In this paper,the Xinyu section of Yuan river and the sediment of fairy lake were investigated,and the single factor pollution index method,potential ecological hazard risk assessment and geological accumulation index method were used to evaluate,in order to fully understand the cadmium pollution event of fairy lake and the content and morphology of cadmium in the sediment.Cadmium content in underground and aboveground parts of acorus japonicus in the study area was analyzed and the correlation between sediment and all parts of acorus was analyzed to determine the enrichment coefficient,transfer coefficient and retention rate of acorus calamus.Cadmium content and markers of superoxide dismutase(SOD),catalase(CAT),glutathione thiotransferase(GSH),reduced glutathione(GST)and malondialdehyde(MDA)in the feet and viscera of benthic piriform spiral snails were analyzed.The conclusions of this paper are as follows.(1)According to the survey results,compared with the background values of soil cadmium in Jiangxi province and the whole country,the sediments in the study area were seriously polluted by the heavy metal cadmium,and the cadmium content in almost all the sampling points exceeded the background values.The mean Cd content in the main stream of the Yuan river exceeded the standard by 22 times,the mean Cd content in the tributaries of the Yuan river exceeded the standard by 12 times,the mean Cd content in the main lake area exceeded the standard by 27 times,the mean Cd content in the tributaries of the main lake area exceeded the standard by nearly 4 times,and the background point exceeded the standard by nearly 2 times.The size order is as follows: main lake area> main stream of Yuan river> tributary of Yuan river> tributary of main lake area> background point.(2)The relationship between the mean value of the heavy metal cadmium morphological content in sediments in the study area shows that the mean value of the four morphological forms in different study areas is somewhat different,and the residual state content in the four study areas is generally higher.In the main stream of Yuan river,residual state > reduced state> acid soluble state > oxidizable state.In the tributary of Yuan river residual state > acid soluble state > oxidizable state > reduced state.In the main lake area,residual state > acid soluble state > reduced state> oxidizable state.In tributary of main lake area,residual state > oxidizable state > reduced state> acid soluble state.(3)The total amount of heavy metal Cd in the sediment in the study area was evaluated for pollution.The calculation results of single factor pollution index evaluation showed that the majority of sediments in this area were evaluated as severe pollution level,and a small number of sediments were moderately polluted.The results of the potential ecological hazard index method show that the difference of EI pollution risk values between different sampling points is relatively large.The background points and the tributaries of the main lake area mainly show medium ecological hazards,while the main streams,tributaries of the Yuan river and the main lake area mainly show strong ecological hazards.The results of the ground accumulation index method show that: the whole research area is mainly manifested as medium and heavy accumulation.From the above three evaluation results,the evaluation results of the three methods show that there is serious heavy metal cadmium pollution in the study area,and the evaluation results are basically consistent,but there are also some differences.(4)Risk assessment of heavy metal cadmium forms in sediments in the study area was carried out.The results of heavy metal forms evaluation by RSP method of distribution ratio between secondary phase and primary phase showed that background points,main stream of Yuan river,tributaries of Yuan river and tributaries of main lake area were mainly mildly polluted,while those of main lake area were mainly moderately polluted.(5)The content distribution characteristics of cadmium in the roots and leaves of calamus,an aquatic plant,and the size of cadmium in the growth organs were ranked as follows: root > leaf.The enrichment coefficient of calamus root and leaf was greater than 1,the enrichment coefficient of root was greater than that of leaf,and root had better enrichment ability than leaf.The transfer of heavy metal Cd in acorus calamus was weak.The retention rate of acorus calamus on Cd was more than 50%,and had a strong retention effect.The correlation analysis of heavy metals between calamus and sediment showed that there was a strong correlation between different organs of calamus and sediment(P < 0.01).(6)The distribution characteristics of heavy metal cadmium in the internal viscera of piriform fritillaria showed that the accumulation of heavy metal Cd in the internal viscera of piriform fritillaria was much higher than that in the feet.(7)The response law of SOD,CAT,GSH,GST and MDA in the visceral sac and foot of piriculus edulis showed that the heavy metal content of the visceral sac was not significantly positively correlated with SOD,CAT,GSH and GST,but significantly negatively correlated with MDA.The correlation between antioxidant enzymes SOD,CAT,GSH and GST was significantly positive.There is a negative correlation between them and MDA.There was no significant positive correlation between foot heavy metal content and CAT,GSH,SOD and GST,and MDA.(8)By using the comprehensive biomarker response index method to study the response of each marker to heavy metal pollution pressure,it was found that the IBR value of visceral sac,main stream of yuan river>tributary of yuan river>main lake area> tributary of main lake area>background point.IBR value of foot,main stream of yuan river> main lake area>tributary of yuan river>tributary of main lake area>background point. |
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