Analysis Of The Effect Of Typical Sponge Facilities On Heavy Metal Removal And Its Influence

At present,heavy metal pollution in urban rainwater runoff is serious,which has become a prominent environmental problem.Numerous studies at home and abroad have shown that biological retention measures can effectively remove heavy metals in rainwater runoff,with a removal rate of over 90%.This article is based on the established Yuelai New City road bioretention zone.From July 2019 to January 2021,the planting layer of the bioretention zone of different areas and different plant types after rainfall was sampled on-site to analyze the content of heavy metals in the soil and plants,Clarify the temporal and spatial distribution characteristics of heavy metals,further study the transfer capacity and enrichment capacity of plants and soil to heavy metals,and use this as a basis to analyze and study the influence of soil and plants on the removal of heavy metals in the biological retention zone,and simultaneously study the net pollution of the filler-enhanced biological retention zone The main conclusions of the study are as follows: The content of heavy metals in the road bioretention zone of different types of land in the city is little different,and it is mainly concentrated in the bioretention zone at a depth of 0-10 cm.(1)The heavy metal pollution in the rainwater runoff of Chongqing Yuelai is obvious.The initial scouring peaks of Cd,Zn,and Pb all exceed the standard value of Category V of the "Surface Water Environmental Quality Standard".The actual removal effect of heavy metals in the biological retention zone is 78.52% for Cu,65.89% for Zn,74.31% for Mn,9.65% for Pb,23.60% for Ni,and 16.38% for Cd.After the treatment,except for Cu,it still fails to reach the Class V standard value of "Surface Water Environmental Quality Standard".(2)The soil shows a good enrichment capacity for Cu and Mn,which is about 20 times that of the lowest Ni and Cd.In addition,soil enrichment of heavy metals shows certain seasonal characteristics,and the overall performance is strong in autumn and winter.(3)Different plants and plants of different sizes of the same species show certain differences in organs rich in different heavy metals.The strong transfer ability indicates the strong transfer ability of heavy metals in the plant from the roots to the above-ground parts,and the strong enrichment ability indicates the strong transfer ability of heavy metals from the sediment or soil to the plants,which means that the plants have strong ability to remove heavy metals.As far as the average transfer coefficient of plants is concerned,Canna has the best transfer ability to Cu,Zn,Mn,Pb,and Cd,while Pinwheel grass has the best transfer ability to Ni.As far as the average enrichment coefficient of plants is concerned,Pennisetum has the strongest enrichment ability for Cu,Zn and Cd,while Canna has the strongest enrichment ability for Mn,Pb and Ni.The strong transfer ability indicates the strong transfer ability of heavy metals in the plant body from the roots to the above-ground parts,and the strong enrichment ability indicates the strong transfer ability of heavy metals from sediment or soil to plants.In addition,for Cd canna,calamus and windmill grass occasionally reached the enrichment threshold,but the average enrichment did not reach the threshold,which can be used as potential enrichment plants for Cd.(4)Experimental study on the cleaning effect of the filler-enhanced biological retention zone: Six fillers including perlite,zeolite,ceramsite,volcanic rock,activated carbon vermiculite and quartz sand were initially selected,and perlite,zeolite and quartz sand were screened out by measuring the removal effect of different heavy metals in the filler As a filler component for further experiments.Zeolite,quartz sand,perlite and local purple clay are uniformly mixed in different proportions to obtain a total of 13 sets of composite fillers.It can be seen that the cleaning ability of the filler on the biological retention zone has been enhanced,and the removal rate of Cu,Zn,Mn and Cd can reach more than 70%,and the effect on Pb and Ni is slightly worse,but the removal rate is also about 30%.Around 60%.