Research On The Impact Of Human Activities On Rare Earth Elements And Trace Elements In Urban Rivers

Due to the wide application of rare earth elements in modern industries such as wind power generation,electric vehicle engines,petroleum refining,nuclear power industry,medical diagnosis,agriculture and other fields,the use of rare earth elements has increased rapidly in the past few decades.The more anthropogenic rare earth elements are discharged into the aquatic ecosystem,it is bound to have a profound impact on the content and distribution pattern of rare earth elements in the water body.The rapid development of Chinas industry,the acceleration of urbanization,and the transformation and upgrading of the industrial structure will inevitably produce a large amount of anthropogenic rare earth elements and trace elements,which will put increasing pressure on the urban sewage treatment system and the water environment that receives its discharge.In this study,Guiyang City was taken as a typical area.The system collected samples from 40 urban rivers in the Nanming River Basin of Guiyang City.Inductively Coupled Plasma Mass Spectrometry(ICP-MS)was used to determine the content and distribution characteristics of dissolved rare earths and trace elements.The results show that the total rare earth element content in the Nanming River Basin is between14.65～116.88 ng/L,the range of change is up to 7.98 times,and it shows obvious enrichment of medium and heavy rare earth elements,and there are different degrees of negative Ce anomalies and Eu positives.unusual phenomenon.The negative Ce anomaly is mainly controlled by the redox conditions of the water body;while the positive Eu anomaly is related to the local geological conditions and the weathering and transportation process,but there may also be potential input,and further investigation is urgently needed.In addition,there are obvious positive Gd anomalies in the mainstream of Nanming River and Jinzhong River,and the anthropogenic Gd concentration is estimated to be between 0.73 and 84.82 ng/L.The proportion of manmade Gd in the effluent of Xinzhuang,Jinyang and Xiaohe sewage treatment plants reached 98.5%,95.0% and 90.2%,respectively,which may be related to the Gd contrast agent used in magnetic resonance imaging(MRI).By comparing the relationship between the Gd concentration and the distance after the wastewater from the sewage treatment plant enters the river,it is found that the Gd concentration in the urban wastewater is mainly controlled by dilution and water chemical conditions.In addition,9 trace elements such as Mn,Co,Al,Ni,Ba,V,Li,Sr,Fe and so on in the study area are less polluted.Only one sampling site is affected by Mn and has moderate trace element pollution.By comparing the trace elements and rare earth elements in the Nanming River Basin of Guiyang City,it is found that the anthropogenic Gd element has a good correlation with the total trace elements in the water body and has a certain indicating effect.