Effects Of Reclamation On Soil Properties And Migration And Transformation Of Heavy Metals In Carbonate Area

Heavy metals have a high background property on the soil that is developed from Carbonate rocks,but the majority of soil heavy metals are in a "high background / low activity" state..Research the Guizhou high background area reclamation effects on Transformation of soil properties and heavy metal migration can help us to find effective measures to reduce the exposure risk of heavy metals in agricultural products and provide the basis for prevention and control of soil environment pollution as well as the quality and safety of agricultural products.In this sutdy,we use the method of space instead of time,throughing the field survey sampling and laboratory analysis combined analysis of the carbonate rock area of different reclamation and planting mode,the variation of soil basic properties and heavy metals in the soil and their relationship,the main results are as follows:(1)The contents of bulk,organic matter,available phosphorus and total phosphorus in soil under different reclamation years decreased with the increase of sampling depth,while the pH is increased;In the early stages of reclamation 0a,3a and 8a,with the increase of the sampling depth,the percentage of clay particles(<0.001mm)in the soil increased greatly,Coarse silt(0.01-0.05mm),coarse sand and medium sand(0.25-2mm)and fine sand(0.05-0.25mm)decreased,the topsoil and subsoil(0.005-0.01mm)and fine silt(0.001-0.005mm)do not vary with the sampling depth.In the cultivated 35 a and 55 a,there was no significant difference in the percentage change of soil particle size with the increase of sampling depth.(2)With the increase of reclamation period,the contents of pH,available phosphorus and total phosphorus in different soil layers were increased;The soil bulk density and organic matter in the Subsoil layer and bottom layer increased;There is no obvious change in the percentage of different particle sizes in the topsoil;Subsoil in coarse sand and medium silt(0.25-2mm)?fine sand(0.05-0.25mm)? coarse silt(0.01-0.05mm)? system silt(0.005-0.01mm)? fine silt(0.001-0.005mm)the percentage with reclamation increased overall showed an increasing trend,while the percentage of clay(<0.001mm)is reduced;Substratum in coarse sand and medium silt(0.25-2mm)?fine sand(0.05-0.25mm)?coarse silt(0.01-0.05mm)?system silt(0.005-0.01mm)the percentage with reclamation increased overall showed an increasing trend,while the percentage of fine silt(0.001-0.005mm)and clay(<0.001mm)showed a decreasing trend.(3)The total amounts of Cu,Zn,Pb,Cd and Cr in the soil under different reclamation years showed an increasing trend with the increase of sampling depth.With the increase of reclamation period,the heavy metals Pb and Cr in the topsoil showed a slow increasing trend,while Heavy metals Cu,Zn and Cd showed elevated first,then decreased,and then increased again at early stage of reclamation.In the subsoil,the heavy metal Zn showed a slow increasing trend,heavy metals Cu,Pb and Cd decreased after increasing trend in the initial stages of reclamation,heavy metal Cr showed an upward trend between 0-8a at the early stage of reclamation,decreased at 35 a,and then increased again.In the bottom layer,the heavy metals of Zn,Cr and Cd showed up in the initial stages of reclamation,reducing the tendency of rising,the heavy metal Cu showed an increase in 0-8a during the early stage of reclamation,and then decreased to stabilize,the heavymetal Pb showed a tendency to decrease at the beginning of reclamation and then increase.By correlation analysis,the heavy metals Zn,Pb and Cr was affected by p H,Cu and Cd are greatly affected by organic matter and coarse sand and sand content.(4)Different reclamation of soil heavy metals Cu,Zn,Pb,Cd and Cr in different forms,the residual state is the highest proportion,and the other contents were lower.The forms of heavy metals in soil under different reclamation years has a not consistent change with Sampling depth and reclamation period,while the change trend of heavy metal residue is basically the same as that of heavy metal.(5)The degree of change of the basic attributes of soil under different planting patterns is different.The basic attribute of soil after harvest were compared with that before planting showed : the pH was increased by single and continuous cropping while intercropping is the opposite;Organic matter,available phosphorus and total phosphorus increased slightly;The contents of fine sand(0.05-0.25mm)and medium silt(0.005-0.01mm)showed a decrease in single work,increase in continuous cropping and intercropping;The content of coarse silt(0.01-0.05mm)increased in all three modes while fine silt(0.001-0.005mm)and clay(<0.001mm)showed a decrease in all three modes.The contents of Cu,Zn,Pb,Cd and Cr in the soil under different planting patterns were similar,which were lower than those before planting.