Geochemical Characteristics Of Rare Earth Elements In Taihu Lake And Analysis Of The Influence Of Human Activities

The rapid development of new technologies also means the release of new potentially toxic pollutants,such as rare earth elements,which have been widely used in aerospace,electronic information,nuclear industry,metallurgy and permanent magnet materials in recent years,because the amount released into aquatic ecosystems through sewage treatment systems is also increasing.However,there are few studies on the geochemical characteristics of rare earth elements in freshwater lakes and the effects of human activities.Therefore,in this study,a total of 26 sampling points were collected from 6 major lakes of Taihu Lake.Inductively coupled plasma mass spectrometry(ICP-MS)was used to measure the concentration of dissolved rare earth elements at each sampling point and divide its distribution characteristics.The following conclusions were drawn by calculation and comparison with other lakes in the world: The total REE contents in the Taihu Lake ranged from 20.94-255.22 ng/L,with a difference of 12.2 times.The spatial distribution of REE concentrations was high in the west and low in the east.The spatial distribution of REE concentration is higher in the west and lower in the east,with a 12.2 fold difference.The standardized partition pattern diagram of shale in the study area shows that the enrichment characteristics of medium and heavy rare earth are obvious,and there are negative Ce anomalies and positive Eu anomalies in different degrees,which are mainly affected by the local redex conditions,original rock types and weathering conditions.In addition,there are significant anomalies of La,Sm and Gd from anthropogenic sources in the Taihu Lake Basin,with the average proportion of anthropogenic sources being 49%,37% and 58%,respectively.The average concentration of La,Sm and Gd in the western Taihu Lake is higher than that in the eastern Taihu Lake,especially in Zhushan Lake.There are a number of petrochemical enterprises and high-tech industrial clusters in Wuxi,Huzhou and Changzhou,which may be the main reason for the anomaly of La and Sm in the western Taihu Lake.However,anthropogenic Gd mainly comes from Gd contrast agent in magnetic resonance imaging.Taihu Lake Basin is densely populated and has developed medical services,so traditional sewage treatment plants cannot effectively remove Gd from medical wastewater and release it into the water environment with drainage.Although the risk of rare earth elements to human health has not been determined yet,attention should be paid to the abnormal rare earth elements in Taihu Lake,which is an important source of drinking water and industrial and agricultural water for surrounding cities.