Study On Sediment Pollution Characteristics And Phosphorus Occurrence Forms Of Tuo River In Suzhou

Research on the environmental quality of rivers flowing through urban areas has always been a hot topic in the field of water environment.In particular,the pollution of heavy metals and nutrients in rivers caused by urban economic activities and residents’lives has attracted more and more attention from the society.Sediment,as the source and sink of water pollution,is an important carrier for water environmental quality research.Carrying out environmental research on urban river sediments is of great significance for water environmental quality assessment and pollution prevention and control.Tuohe river is a main river flowing through Suzhou.This paper takes the river sediments as the research object.Firstly,the distribution characteristics and sources of heavy metals are analyzed,and the pollution level of heavy metals in sediments is evaluated by geoaccumulation index method and potential ecological risk index method.Secondly,the content and distribution characteristics of nutrients(OM,TN,TP)were studied,and the occurrence status of nutrients was evaluated by comprehensive pollution index method and organic pollution index method.Finally,based on the analysis of the existing forms of phosphorus in sediments,the experimental study on the effect of magnetic iron zirconium modified zeolite(FeZrMZ)on phosphorus migration and form transformation was carried out.The main conclusions are as follows:(1)The order of the average content of heavy metals in sediments is:Mn>Zn>Cr>Cu>Ni>Pb>As>Cd,which are 1.14,1.75,0.95,1.71,1.02,0.83,1.74,5.46 times of the background value of each element.Except for Cr and Pb,which are slightly lower than the soil background value in Anhui Province,the other 6 heavy metals are all enriched in the sediments.(2)The evaluation results of heavy metals in sediments show that Cd is the main pollution factor,and As,Zn and Cu are the pollutants second only to Cd,which are at the level of mild pollution.The characteristics of heavy metal pollution in different river sections are that the pollution degree of TS section located in the suburbs is the lowest,followed by SB section,and the pollution degree of BT section passing through the urban area is the highest.(3)The spatial distribution characteristics of OM,TN,and TP are similar,and they all show the highest content of the BT section.The reason is that the BT section is located in the urban area and is obviously affected by human activities.The comprehensive pollution index and organic pollution index evaluation results show that most of the sampling points are in different degrees of pollution.Among them,the nutrient pollution in the BT section is the most serious,with moderate or severe pollution.The "contribution" of total phosphorus(TP)is relatively high.protrude.(4)The indoor sediment static release experiment results show that the prepared FeZrMZ material has good magnetic separation ability,can effectively reduce the concentration of SRP in sediment overlying water and interstitial water,and can remove unstable potential active phosphorus(NH4Cl-P and BD-P).)Is transformed into more stable NaOH-P and Res-P,and can effectively reduce the content of AAP,Olsen-P,WSP and RDP in the sediment.Figure[30]Table[20]Reference[109]...