Assessment of Heavy Metal Pollution and Health Risk in Farmland in Volcanic Weathering Area:A Case Study in Jiangdong New District of Haikou

Zuo Wenping; Li Qinghua; Zhang Yanpeng; Chen Shuai

doi:10.3799/dqkx.2022.074

Abstract：In order to investigate the heavy metal pollution level of soil and rice in the geological high background area dominated by volcanic weathering,taking the west of Jiangdong new district in Haikou as the research object,82 soil-rice matching samples were collected to measure the contents of As,Cd,Cu,Hg,Ni,Pb and Zn in soil and rice,and the geo-accumulation index method,Nemerow index method,matter-element extension model,the potential ecological risk assessment method were used to evaluate the pollution of farmland soil in the study area,using correlation analysis and PMF model to explore its main sources and contribution rate,and evaluate the health risk of rice consumption.The results show that there are severe Cu,Ni and Zn pollution in the study area,compared with the background value of soil in Hainan Province,the over standard multiples are 2.00,2.77 and 1.94 respectively,and compared with the risk screening value of agricultural land,the over standard rates are 23.17%,17.07%and 7.32%respectively.The land accumulation index method shows that As and Pb in farmland soil in the study area are in a pollution-free degree,and the pollution degree of other heavy metals is Ni>Cu>Zn>Cd>Hg,the pollution degree of Ni element is relatively large,and 7.31%of soil samples are of"medium strong pollution".The comprehensive pollution assessment results show that the pollution area is mainly concentrated in the south of volcanic rocks.Combined with PMF source analysis and spatial analysis results,Hg mainly comes from atmospheric sedimentation.The excessive contents of Cu,Ni and Zn are mainly caused by the weathering of volcanic rock soil forming parent material,Pb mainly comes from traffic pollution sources,and the contents of As and Cd are greatly affected by agricultural activities.There is a certain degree of health risk to human body by having rice,and As and Cd are the main contributing factors.The contents of As,Pb and Hg in rice are lower than the national food safety limits,and the over standard rate of Cd reaches 32.93%,there is a certain degree of health risk to human body by eating rice,As and Cd in rice seeds have a great impact on human health risk,with the contribution rates to non carcinogenic risk of 51.52%and 21.57%respectively,and the contribution rates to carcinogenic risk of 73.88%and 26.01%respectively.In conclusion,the farmland soil in the study area is polluted to a certain extent under the joint influence of volcanic rock weathering and human activities,the content of As in rice does not exceed the standard,but it is the largest potential risk element,it is necessary to focus on the health risks of As and Cd in rice produced in the study area,and formulate scientific and reasonable prevention and control strategies for farmland heavy metals.