| There is increasing concern about the heavy metal accumulation during the greenhouse vegetable production in China.To quantitatively explore the effects of heavy metal accumulation,risk,and the potential corresponding factors（e.g.,planting years,nutrient input,and humus substances etc.）,the heavy metal content of greenhouse vegetable soil from literatures and soil samples were collected and analyzed.The main results were as follows:（1）The heavy metal content of soil is at a low level in most greenhouses in China.In the nationwide,the content of soil Cd,Pb,As,Cr,Hg,Cu,Zn,and Ni was 0.15、22.87、7.48、44.79、0.07、25.77、77.05、22.20 mg·kg-1.In addition,compared with Chinese Soil Quality Criterion（GB 15618-2018）,about 14.7%,3.3%,3.1%,2.3%,2.0%,and 1.1%of total soil samples exceeded the threshold of Cd,Cu,Cr,As,Zn,Pb.Furthermore,the content of soil Cd,Pb,As,Cr,Hg,Cu,Zn,and Ni from literatures was 0.32,24.9,8.45,83.6,0.05,29.9,70.7,and 27.4mg·kg-1,respectively.In addition,compared with Chinese Soil Quality Criterion（GB15618-2018）,about 30.5%,9.8%,7.2%,4.8%,4.7%,and 3.7%of total soil samples exceeded the threshold of Cd,Cu,Cr,Zn,Pb,As.The content of soil Cd,Pb,As,Cr,Hg,Cu,Zn,and Ni from collected soil samples was 0.13,21.9,6.48,41.9,0.09,23.6,72.1,21.4 mg·kg-1,respectively,and the ratios of exceeding threshold were 5.3%,1.8%,1.6%,0.9%,0.6%,and0.6%for Cd,Cu,As,Zn,Pb,Cr respectively.In the Huang-Huai-Hai and Bohai Rim region,the content of soil Cd,Pb,As,Cr,Hg,Cu,Zn,and Ni from literatures was 0.30,25.9,8.56,67.1,0.08,33.3,79.1,and 32.5 mg·kg-1,respectively.In addition,compared with Chinese Soil Quality Criterion（GB 15618-2018）,about 25%,10.4%,9.9%,6.3%,2.2%,and 2.1%of total soil samples exceeded the threshold of Cd,Cu,Cr,Pb,Zn,As.The content of soil Cd,Pb,As,Cr,Hg,Cu,Zn,and Ni from collected soil samples was 0.13,22.8,5.93,43.5,0.08,23.1,69.3,19.4mg·kg-1,respectively,and the ratios of exceeding threshold were 3.1%,2.1%,2.0%,1.2%,0.6%,and 0.5%for Cd,Cu,Cr,As,Pb,Zn respectively.In the field of long-term experiment,Cd,Pb,Cr,Cu,Zn in soil accumulate,and only Cd content exceeded the threshold of the standard.Overall,the findings show that the dominant pollution element is Cd,and the soil is susceptible to be polluted by Cd,As,Cu,and Zn other than Hg and Ni.（2）Based on a large amount of data,the main affecting factors of heavy metal accumulation in greenhouse vegetable soil were analyzed to provide theoretical basis for the prevention and control of heavy metal pollution.The results showed that the contents of Cd,As,Cu and Zn in soil were accumulative with planting years,and Cd,Cu and Zn were greatly affected by planting years.Heavy metal contents in fertilizers and soils further verified the homology of Cd,Cu and Zn accumulation and nutrient inputs,that is,the results were affected by inputs of phosphate fertilizer and heavy metal contaminated manure.As the leading pollution factor,Cd accumulates under long-term fertilization,and gradually changes to a stable state with the increase of phenolic hydroxyl group and carboxyl group in soil humic acid reacting with metal and increasing of aromaticity.（3）With the improving matter-element extension model and human health risk assessment,the ecological and health risks of heavy metal pollution in greenhouse vegetable soil were evaluated.The results indicate that the heavy metal content of soil is at a low level in most greenhouses in China.The results of the improved matter-element extension model assessment showed that 92.7%of soil samples are clean,and some samples reached slight（4.9%）,moderate（0.8%）and severe（1.6%）risk of soil pollution.Ecological risk is mainly affected by metal of Cd and Cu.Pollution prevention and control measures shall be taken for soils with the pollution level III and above.In the health risk assessment,the non-carcinogenic health risks of most of the samples are at an acceptable risk level,and there is no carcinogenic risk to the human body.Only a few samples have non-carcinogenic and carcinogenic risks.Among different populations,the non-carcinogenic risk index for children is relatively high,the carcinogenic risk index for adult women is relatively high,and the non-carcinogenic and carcinogenic risks for adult men are low. |
