| Field repair demonstration in Tielong of Shaoguan City was taken as the object in this study.Based on the survey and evaluation of soil and agricultural products pollutions,this study had researched Morus alba L.,Zea mays L.and Oryza sativa through the type of heavy metal pollutions and the degree of pollutions in the soil.In order to provide data for local farmland soil heavy metal pollution prevention and agricultural product safety data accumulation.The results were as follows:?1?The surface soil?0-20 cm?of Tielong was heavily contaminated by heavy metals.The main pollutants were Cd,Hg,As,Pb and Zn,and the exceeding rates were 100%,4.90%,68.63%,39.22%and 22.55%respectively.The evaluation results of Nemerow's comprehensive pollution index method showed that among the 102 soil samples collected at Tielong Forest Farm,there were no clean soil samples,2 cordon samples,accounting for1.96%,and 30 light pollution samples,accounting for 29.41%;39 samples were moderate polluted,accounting for 38.24%;31 samples were heavily polluted,accounting for 30.39%.Therefore,this study intended to select moderate and heavily polluted farmland as a repair test site to carry out rehabilitation test research.?2?Morus alba L.could survive and grow by adjusting the planting structure in heavily polluted farmland.The content of Cd in leaves was 0.043-0.068 mg·kg-1,As was0.009-0.018 mg·kg-1,and Pb was 1.236-1.574 mg·kg-1.The heavy metal content in the leaves reached the requirements of the feed hygienic standard.?3?Zea mays L.were planted in heavily contaminated farmland after the using of soil conditioner.The results showed that,the average content of Cd in the grain of Caitiannuo 3 was 0.023 mg·kg-1,As was 0.007 mg·kg-1,and Pb was 0.042 mg·kg-1.The average content of Cd in the grain of Caitianxianfeng was 0.021 mg·kg-1,As was 0.008mg·kg-1,and Pb was 0.015 mg·kg-1.The average content of Cd in the grain of Jingke 783was 0.011 mg·kg-1,As was 0.018 mg·kg-1,and Pb was 0.033 mg·kg-1.The contents of heavy metals in the three varieties did not exceed the National Food Safety Standard-Contaminant Limits in Foods?GB2762-2017?.Based on the comprehensive analysis,Caitianxianfeng had the lowest absorption of three heavy metals.?4?Three different soil conditioners were applied to medium contaminated farmland and Oryza sativawas planted.The results showed that there was a soil conditioner?I?only that had a certain passivation effect on As and Pb,and the As content in rice was also decreased with 22.37%of reduction rate.The content of available Cd and Pb in the soil has declined by used the soil conditioner II.The reduction rate of Cd was 14.40%and the reduction rate of Pb was 13.64%.At the same time,the Cd content in rice was also relatively decreasedwith 2.30%of the reduction rate.The effective content of Cd in the soil decreased by 21.51%,the content of available As in the soil decreased by 22.22%,and the content of Pb in the soil decreased by 4.67%after using the soil conditioner III.However,there were no significant differences in soil available state and rice about Cd,As,Pb and Cd,As,and Pb in different treatment soils?p<0.05?.?5?Meixiangzhan was planted in moderately contaminated farmland,the average content of Cd in rice was 0.159 mg·kg-1,inorganic As was 0.144 mg·kg-1,Pb was not detected.The contents of Cd,inorganic As,and Pb in rice all reached the requirements of national food safety standard?GB2762-2017?. |
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