Pollution Investigation And Morphological Analysis Of Heavy Metals In Soil Of A Mining City In Hubei Province

The rapid development of the social economy has brought a large amount of heavy metal into the soil.Therefore,the pollution of heavy metals in the soil has gradually attracted people's attention.With the heavy metal entering into the soil,the soil environment is gradually deteriorating,which not only affects the growth and development of crops,reduces the yield and quality of agricultural products,but also endanger human health through the food chain.The correlation analysis of heavy metals in soil has been a hot issue worldwide.In this paper,the total amount of heavy metals in the soil was detected by flame atomic absorption spectrophotometry,and learning morphological distribution of heavy metals by BCR sequential extraction procedure,which can be used to to analyze bioavailability of heavy metal.Single pollution index method,Single potential ecological risk indexs method and comprehensive potential ecological risk indexs method,The Nemerow multi-factor index method and Improved AHP method were used to evaluate the pollution of heavy metals.The heavy metal of plants were tested to obtain enrichment coefficient of plants.Analyzing changing trend of heavy metals in leaching solution by simulating acid rain with different pH values,so as to provide theoretical basis for studying the migration of heavy metals and potential harm to soil.By adding certain amount of humic acid into the soil and controlling the reaction conditions,the morphological changes of heavy metals were detected to systematically learn the influence of humic acid on the morphological distribution of heavy metals in different environments.The main results are as follows:?The total amount of heavy metals such as Cr,Cd,Pb,Zn,Cu,As was detected,and it was found that Pb,Zn,Cu and As were all higher than the soil background value in hubei province,while Zn and Cu were both higher than the national standard.The morphological distribution of heavy metals Cr,Zn,Cu and Pb in the 11 samples were analyzed,and Residual speciation accounted for a small proportion,while Acid Extractable speciation,Reducible speciation and Oxidizable speciation accounted for a large proportion.However,the soil in the city was neutral or weakly alkaline,which reduced the migration and transformation of heavy metals and their toxicity to organisms.?Five methods were used to evaluate and analyze the pollution of Cr,Cd,Pb,Zn,Cu,As.Single pollution index indicated that Cu ang Pb was contaminated,Cr was not contaminated.Single and comprehensive potential ecological risk indexs proved that the heavy metals in the sampling were basically minor pollution.However,The Nemerow multi-factor index method proved that the pollution from heavy metals was extremely serious.Adopting Improved AHP to evaluate the pollution degree of heavy metals in soil,which is minor pollution.?Bioavailability of heavy metals Cr,Pb,Zn and Cu in the soil was analyzed,and the conclusions was that the DAC values of Cr,Zn and Cu are nearly equal,greater than the DAC values of Pb(DAC=0.10).Therefore,the sum of available and potential available coefficient of Cr,Zn and Cu were nearly equal,and their bioavailability were similar.Pb had the smallest proportion of difficult available coefficient and high bioavailability.?Heavy metals such as Cr,Cd,Pb,Zn,Cu,As in plants around the sampling site were detected,and it was found that among plants,the content of Zn was the highest,followed by Cu,and the content of Cd was the lowest.On the whole,among the eight kinds plants selected randomly,the Conyza Canadensis had the best enrichment ability for heavy metals Pb,Zn,Cu and As,while the Broussonetia papyrifera had the least enrichment ability for heavy metals Cr,Pb and Cu.?Acid rain with different pH values was simulated to leach the soil,and the experimental results showed that the release rules of heavy metals were similar,that were,with the increase of leaching amount,the heavy metal concentration increased from high to low,and then the release rules were stable.The sequencing of leaching amounts of the five heavy metal elements are Zn >Cu >Pb >Cr >Cd.Which were not only related to the content and morphological distribution of heavy metal,but also related to the changes of heavy metals in an acidic environment.?Adding a certain amount of humic acid to the soil can change morphological distribution of heavy metals.With the addition of 10% humic acid,the Acid Extractable speciation of Cr,Zn,Cu and Pb decreased and the Oxidizable speciation increased.The content of Acid Extractable speciation of Pb decreased with the increase of humic acid,temperature,and pH value.By reducing the proportion of non-stable heavy metals,Bioavailability can be reduced and reducing the harm to the ecological environment.