| The ginger industry is the dominant characteristic industry in Luoping County,Yunnan Province,which has a complete industrial chain and is one of the pillar industries of Luoping’s economy.At the same time,heavy metal pollution risk exists in ginger fields,but there are few reports on heavy metal pollution of ginger in Luoping.Therefore,this study takes ginger in Luping as the research object,studies its pollution situation,enrichment characteristics and cadmium reduction technology,identifies the pollution risk and applicable conditioner,and provides theoretical and practical basis for the Cd pollution remediation of rhizome.The main research results are as follows:（1）According to the agricultural land pollution risk control standard of soil environmental quality,the rates of Cd,As and Cr exceeding the risk screening value were90%,71.67%and 90%,respectively,and the rates exceeding the strictly controlled value were 6.67%,3.33%and 1.67%,respectively.The order of heavy metal accumulation degree was Cd>Cr>As,and the order of heavy metal pollution ecological risk from ecological risk index4)was Cd>As>Cr.Among them,Cd is the heavy metal with the greatest pollution degree and the greatest ecological risk.According to the spatial distribution and source analysis of heavy metals,the contribution rate of industrial sources to Cd is the largest,reaching 50.16%.（2）The results showed that the BCF of small yellow ginger to Cd presented the characteristics of stem>leaf>rhizome,and Cd mainly concentrated in the stem.The single factor pollution evaluation index method was used to evaluate rhizome samples（edible parts）in the study area,and 11 samples were both mildly polluted and severely polluted,accounting for 9.17%of the total samples.（3）The results showed that BCF in rhizome was significantly negatively correlated with soil p H and CEC,Cd content in rhizome was significantly positively correlated with Cd content in rhizome and leaf,BCF in rhizome,soil Cd content and soil DGT-Cd,and negatively correlated with soil p H.There was a negative correlation with TF（rhizome-stem）.（4）Field experiments were carried out by applying in situ conditioner.Compared with CK,soil p H increased by 0.32～2.15 units after adding soil conditioner,and the content of effective Cd decreased by 8.54%～43.54%（except NTT）.The application of YSK and AMS promoted the conversion of Cd from exchangeable state to Fe-Mn oxide binding state and organic state,and the application of TXT promoted the conversion of Cd from exchangeable state to carbonate binding state and Fe-Mn oxide binding state.The restoration effects of NTT,TXT,YSK and AMS were all good.Compared with CK,the underground biomass increased by 32.30%to 65.45%,the Cd content of rhizome decreased by 60.71%to 81.33%,and the BCF decreased by 64.67%to 84.98%.However,leaf surface conditioner had little effect on Cd content and BCF in rhizome.TXT is 10 kinds of adjusters in the most suitable conditioners. |
