Study On The Changes Of Cadmium And Trace Elements In Rice Cadmium Reduction

Soil is the basis of agricultural ecosystems,and rice is an important food crop.Both are important for humans.At present,the scope and extent of soil cadmium pollution in farmland have increased,leading to excessive cadmium content in rice.Many agricultural scientists have put forward a large number of remediation technologies to deal with cadmium pollution.However,it is difficult to eliminate the negative effects of secondary pollution derived from remediation and missing or excessive trace elements in the soil.Therefore,it is imminent to study the changes of cadmium and trace elements in rice cadmium reduction process.The study focused on cadmium-contaminated paddy fields in the Yuhu region of Xiangtan,based on low-accumulation rice varieties(V),flooding management(I)?regulating Soil pH(pH),and their combination techniques.a total of six treatments were set up.Through the combination of field tests and indoor analysis,the changes of cadmium and trace elements under different repair techniques were studied under different repairing techniques were studied.and their internal correlations were analyzed.The results of the study showed that:(1)Compared with the control,the use of cadmium-low-absorbing rice varieties(V),flooding management(I),application of lime(P),and their combination techniques(VP,IP,VIP)both increased soil pH and reduced the available cadmium content in soil,there was no significant difference in pH and the available cadmium among low-accumulation rice varieties.Low-absorption rice varieties(V),flooding management(I),application of lime(P)and their combination techniques(VP,IP,VIP)increased the available molybdenum and iron content in soil,but reduced the available zinc,copper,manganese content in soil.It can be seen that the use of cadmium reduction technology,especially the application of lime,reduce the soil cadmium effectiveness while also reducing the soil available zinc,copper,manganese content,but increased the effectiveness of iron,molybdenum in soil.(2)Compared with CK,The effect of various remediation techniques on reducing cadmium content in rice is VIP>VP>IP>P>I>V.All the remediation technologies significantly reduced the cadmium content of rice and straw,and also reduced the molybdenum content of rice,but increased the molybdenum content of straw,and also increased the iron content in rice and straw.There was no significant effect on the contents of manganese,zinc,and copper in rice and straw.(3)According to the correlation analysis,the accumulation of cadmium in rice has a significant synergistic effect with molybdenum,and there is a significant antagonism with the presence of manganese,zinc,and iron.The content of cadmium in rice was positively correlated with the content of cadmium in straw,positively correlated with the content of Zn and Cu in straw,but was significantly negatively correlated with the content of molybdenum and iron in straw,but correlated with the content of straw Mn in quadratic parabola.The content of cadmium in rice was positively correlated with the content of available cadmium,and was positively correlated with the content of available Mn,Zn and Cu,but negatively correlated with the available Mo and Fe content.The content of cadmium in rice was positively correlated with the content of available cadmium,and was positively correlated with the content of available Mn,Zn and Cu,but negatively correlated with the available Mo and Fe content.The content of cadmium in straw was significantly negatively correlated with the content of molybdenum and iron in straw,while it was significantly positively correlated with the content of zinc and copper in straw,and was also related to the curve of secondary parabola in straw content.Soil available cadmium content was significantly negatively correlated with soil pH.Soil available molybdenum and iron contents were negatively correlated in the pH range of the experiment,but soil available manganese,zinc,and copper contents were significantly positively correlated.(4)From the primary and secondary transport coefficients of cadmium and microelements in the soil-rice system,the primary transport capacity of rice to cadmium was lower than that of other trace elements,while the secondary transport capacity was at a medium level.The transfer coefficient of molybdenum from the effective state of soil trace elements to rice straw is the highest,followed by manganese,iron,and zinc,and copper is the smallest,while the transport coefficient of cadmium is less than all trace elements.The transport coefficient of molybdenum was the highest among the effective states of soil microelements to rice,Zinc was the second,copper,iron and zinc were smaller,and the transport coefficient of cadmium was less than all trace elements.However,the transport coefficient of copper,zinc,and molybdenum was relatively high during the transfer of trace elements from rice straw to rice.Iron was the second,and manganese was smaller.Trace elements were in rice-soil systems,and molybdenum and zinc were mainly from stems to rice.The transport link is determined,while manganese and iron are mainly determined by the transfer of soil to stems.Copper transported from the soil to stems and stems to rice had comparable transport capacity,indicating that the control of the absorption and translocation of different trace elements by rice is not completely consistent.