Study On Effects Of Different Soil Treatments On Phytoremediation Of Heavy Metal Contaminated Farmland In Gold Mining Area

With the development of society and industry,the problem of soil pollution has become increasingly serious.Heavy metals in the soil are difficult to be decomposed by microorganisms,and are easily accumulated in the soil.Under certain conditions,they are also converted into more toxic methyl compounds,and can accumulate through biological chains to endanger human health.Heavy metal pollution in soil inorganic pollution is harmful and difficult to control.In addition,China's arable land resources are limited,so people and the state are paying more attention to the treatment of heavy metal pollution in farmland soil.Phytoremediation technology has become a hot spot to solve the problem of heavy metal pollution in soil due to its advantages of no secondary pollution,environmental friendliness and low cost.More than 100 kinds of ultra-rich plants have been found,and the corresponding auxiliary strengthening measures have also been widely studied.In view of the fact that most studies on phytoremediation of heavy metal contaminated soil are potted experiments,this study carried out field in-situ remediation experiments on a heavy metal contaminated farmland downstream of yixingzhai gold mine in fanshi county,xinzhou city,Shanxi Province.Selection of a variety of heavy metal plant alfalfa have strong patience and perennial ryegrass in the north as the principal part of repair is added to the soil organic manure,earthworm manure,biochar asauxiliary measures to study the heavy metal content in the soil under different processing and morphological changes and the characteristics of the enrichment of heavy metals by plants,to reveal the effects of the different soil treatment on phytoremediation and explore the efficient,green repair plan,farmland soil heavy metal pollution repair work for the future provide a scientific basis.Through monitoring and analysis of nitrogen,phosphorus,potassium,organic matter content,CEC,urease activity,heavy metal content and morphology,plant height,dry weight,catalase activity in the body and heavy metal content in soil in different periods,the following results can be obtained:(1)the application of organic fertilizer,earthworm feces and biochar in the soil can basically improve the soil nutrient index and urease activity,among which the effect of earthworm feces and organic fertilizer is obvious,while the effect of biochar is general.(2)the application of earthworm manure,organic fertilizer and biochar can increase plant height and biomass accumulation of alfalfa and ryegrass in different stages to different degrees;Earthworm manure and organic fertilizer can significantly increase catalase activity in plants,but biochar has no significant effect.(3)the application of earthworm manure,organic fertilizer and biochar could increase the absorption of heavy metals by alfalfa and ryegrass under different conditions,different treatments combined with different plants have different enrichment effects on various heavy metal elements.(4)the earthworm manure,organic fertilizer and biological carbon can enhance the removal effect of heavy metals in soil and different level of activation heavy metals,the collocation of different plants and applied into the uptake of different kinds of heavy metal elements have preferences,such as alfalfa with organic chicken manure,northern collocation of perennial ryegrass wormcast has good effect to repair in soil heavy metal Cu,alfalfa and northern collocation of perennial ryegrass wormcast has good effect to repair in soilheavy metal zinc;Biochar is not as effective as earthworm manure and organic fertilizer in general,so it can be used as an auxiliary measure in the field for the slow release of heavy metals.