Speciation Transformation Of Sulfur And Heavy Metals And Microbial Ecology Of Paddy Soil Under Different Conditions

There is a special alternating wet-dry process in paddy soil,which will cause conversion from aerobic to anaerobic condition.And this will affect SOB and SRB population distribution.All these changes will finally cause heavy metals speciation transformation and their bioavailability change,going with sulfur speciation transformation.These changing rules and mutual relation should be studied deeply. And it is a meaningful exploration whether reduced metal sulfides form or not and how SRB act in this process when paddy soil drained.This research connected in-site analysis of heavy metal contaminated paddy soil and simulation in lab,to study heavy metals and sulfur speciation transformation and relations between these processes under different condition,and microbial community diversity and changes of biochemistry characters.The major results obtained are as follows.The target soils pH valued between 4.87 and 5.92.Sulfur in mineral soil existed almost in organic combination state.The soil within 1,000 meters from the tailings dumps point was still subject to a certain degree of heavy metals pollution.There was a certain correlation between Soil respiration,soil enzyme activity and the soil moisture content.Soil catalase activity and soil moisture content were not clearly relevant.Soil urease activity showed almost no apparent reaction to soil moisture conditions change.The effection of soil moisture content changes on soil arylsulfatase activity was relatively significant.Contents of each Copper speciation changed with soil water content,the most significant was content of organic bound Copper being upgraded 2.32%.Contents of each Zinc speciation changed as Copper.The detection results of soil biochemical characteristics showed soil sulfur content significantly affect soil respiration rate,and it could change response trend of soil respiration rate to Cu concentrations stress.Cu,Zn stress have a certain degree of inhibition to soil enzyme activity but have different features,and whether additional sulfur also show differences.There were also differences between rice rhizosphere soil and bulk soil in heavy metals speciation. Microbial population structure of rice rhizosphere and bulk soil existed significant differences when dealt with different soil moisture content and different heavy metals stress.And initial amplification of one specie of SRB in aerobic rice rhizosphere soil supplied anaerobic bacteria SRB existing evidence in the special aerobic-anaerobic coexistence ecological environment in presence of dry-wet rice paddy fields.