Heavy Metal Pollution Characteristics And Health Risk Assessment Of Soil In Rosa Roxburghii Base In Guizhou Province

Taking the planting base of roxburgh rosa in A and B areas of Guizhou Province as the research object,this paper investigated the pollution of seven heavy metals in the roxburgh rose base and the enrichment of seven heavy metals in roxburgh rose agricultural products.A total of 122 samples of soil and roxburgh rose agricultural products were collected at sampling sites in the two regions.The total amount and morphology of soil samples were determined by Triacid?HNO₃-HClO₄-HF?electrothermal plate digestion method and BCR continuous extraction method,and the total amount of plant samples was determined by microwave digestion method.Nemerow comprehensive index method,pollution load index method,potential ecological index method and potential health risk index method were used to evaluate soil heavy metal pollution in the study area.Meanwhile,enrichment coefficient method and potential health risk index method were used to study the enrichment characteristics of heavy metals in soil-crop system.The aim was to provide a theoretical basis for the prevention and treatment of heavy metal pollution in soil and agricultural products in the study area.The main results were as follows:?1?The soil in the study area was polluted to a certain extent.Taking thebackground value of Guizhou soil as a reference,seven kinds of heavy metals planted with seed Rosa roxburghii Tratt were planted in area A,except Cr,all the other heavy metal elements exceeded the standard to a certain extent,and the exceeding standard rate of elements was Hg>As=Cu>Cd>Zn>Pb.The seven heavy metals planted in area B of seedless Rosa roxburghii Tratt exceeded the standard except Cr,and theexceeding standard rate was Hg>As>Cd>Zn>Pb>Cu.Compared with thenational standard value of soil pollution risk control of agricultural land,it was found that the other heavy metal elements in area A did not exceed the standard value except Cd,Zn element,and that in area B except Cd,As element,Other heavy metalelements do not exceed the standard value.?2?The results of Nemero pollution index method show that the nationalcontrol value is taken as the standard.The two areas are polluted by different elements and different degrees of heavy metals,and the two areas are mainly polluted by Cd elements.Taking the background value of Guizhou as the standard,area A is mainly polluted by the mixture of Hg,Zn elements,and area B is mainly polluted by themixture of Hg,As elements.The pollution load index method shows that A,B area is in a pollution-free state.The potential ecological risk index method shows that the other elements in area B are at a slight ecological level except that Hg has somepotential ecological risks.According to the comprehensive environmental risk index,A.The sampling points in area B were at the level of mild ecological risk.?3?In addition to Cd in the A and B regions,other elements were mainly in the residual state.In region A,the proportion of the reducible state of Cd was the highest,while in region B,the proportion of the acid extractable state of Cd was the highest,indicating that Cd in region A and B was highly harmful.The RAC risk assessmentindex indicates that the risk of Cd in the A region was the highest,and it was at the medium risk level.In the B region,the risk of Cd was the highest,which was at the higher risk level.Areas A and B should pay attention to the pollution sources and prevention of Cd elements to prevent Cd pollution.?4?The absorption and enrichment of heavy metals by different species of roxburgh rose in the two regions were different,but about the same.The enrichment coefficient of each element of roxburgh rose in area A was in the order ofCu>Zn>Cd>Hg>Pb>Cr>As.The average values of the enrichment coefficients ofeach element in roxburgh rose in region B were:Cu>Cd>Zn>Hg>Pb>Cr>As.Both A and B have the strongest enrichment ability to Cu,while As are the weakest.?5?The health risk assessment model was used to evaluate the health risk of heavy metals in the soil of Rosa roxburghii Tratt base in area A.The results showed that the non-carcinogenic risk of each element in area B was lower than that of adults,and the total non-carcinogenic risk index?HI?was less than 1.The results showed that the total non-carcinogenic risk of all kinds of heavy metals in adults could be ignored.A,the non-carcinogenic risk of each element in area B is lower than that of children,and the total non-carcinogenic risk index of area B is less than 1,which indicates that the total non-carcinogenic risk A of area B is acceptable to children.A,thecarcinogenic risk index?CR?of Cd,Cr,As in area B is less than 10^-6 for adults andchildren,indicating that the carcinogenic risk of Cd,Cr,As elements can be ignored in adults and children.The total carcinogenic risk index?TCR?of adults and childrenwas between the risk threshold of 10^-6and 10^-4,indicating that the total carcinogenic risk was in A,and area B had no health hazard to adults and children.?6?The health risk assessment model evaluates the health risk of roxburgh rose agricultural products in area A and B,and the results showed that:The THQ values of the eight heavy metals in roxburgh rose agricultural products in area A and B were all less than 1,which posed no significant health risk to human body.The total target hazard coefficient?TTHQ?of agricultural products in area A and B were all less than 1,which indicated that there was no significant negative effect of heavy metals on the human body in the agricultural products of roxburgh rose in area A and B.In summary,there are obvious differences in the distribution characteristics ofheavy metals in different regions.The soil of the two roxburghii Tratt growing areas is less polluted by seven kinds of heavy metals,and the long-term consumption of Rosa roxburghii Tratt planted in the study area has no obvious health hazard to the human body.It is suggested that the prevention,control and management of heavy metalpollution in the soil of the study area should be strengthened.