Effects Of Exogenous Organic Matter On The Copper Fractionation In Sewage Irrigation Water And Soil,and Copper Bioavailability In Soil

Water resources in our country are in short supply,and with the development of economy and society,the proportion of industrial water and domestic water is more and more big,and the agricultural water is squeezed seriously,which leads to the problem of agricultural water shortage is becoming more and more prominent.In order to alleviate the tense situation of agricultural water,on one hand,agricultural irrigation is needed to save,on the other hand,it is necessary to develop and utilize available water resources for irrigation.Sewage is used as a valuable water resource,and the emissions of sewage is increasing rapidly.Under such background,sewage should be developed and used urgently for agricultural irrigation.But the sewage contains large amounts of pollutants,if not handled properly,it will lead to heavy metal accumulation in soil.Therefore,the pretreatment of sewage and the remediation of soil after irrigation are necessary measures for agricultural irrigation using sewage.This paper takes the people's victory canal irrigation area as a typical area,to use the organic matters for restoration of contaminated soil and irrigation sewage water.Using exogenous organic matter can reduce activities of heavy metals in wastewater and it could alleviate the shortage of agricultural water resource and lay a foundation for sewage resource.In addition,using organic matter to repair of heavy metal pollution of farmland,can reduce heavy metal bioavailability and improve the heavy metal pollution in soil caused by unreasonable wastewater irrigation.But heavy metals fractionation plays a very crucial role on the activity of heavy metals and exogenous organic matter had important effect on heavy metals fractionation and bioavailability.Elementary laws of the effects of the added different amount of humic acid on fractionation and bioavailability of copper in wastewater was realized first.Then soil culture experiment was taken in this program.In the soil culture experiment,biogas residue,swine manure,sheep manure and chicken manure as organic matter were added into the simulated copper contaminated soil to research the changes of the copper fractionation and bioavailability.Second,pot experiment were taken in this program.The lettuce was chosen as the experimental plant to research on uptakes,accumulations and bioavailability of the soil copper.Elementary laws of the effects of the added different amount of humic acid coal on fractionation and bioavailability of copper in contaminated soil was realized.Finally,fourkinds of inorganic-organic soil stabilizers containing humic acid were tested into the simulated copper contaminated soil to research the changes of the copper fractionation and bioavailability.This method provides a reference for the research of the remediation of heavy metal contaminated.The paper intends to investigate the effects of exogenous organic matter on the remediation of soil polluted by copper,and to provide theoretical basis for the remediation and realize crops safety production.The main results were obtained as follows:When the copper content in the wastewater was 5.77 mg/L,the suspended copper rose most and and dissolved copper dropped most.With the increase of pH,the suspended copper increased under the condition of 3?pH?7,resulting significance reduction of the biological toxicity of copper,and lowering the risks of wastewater irrigation.In soil culture experiments,same phenomena that the residue state copper in the soil increased and the oxidizable state copper in the soil dropped,occurred in the experiment the treatment group and control group.When the exogenous copper in the soil was 0 mg/kg and sheep manure was added in this soil,this phenomenon is the most obvious.Oxidation state copper in the soil decreased by 29% and the residue state copper in the soil increased by 25%.In the soil culture experiment,the biogas residue,swine manure,sheep manure and chicken manure were added in the soil without exogenous copper and this practice improved the effective state copper content.When the four kinds of organic materials were added in the soil with exogenous copper concentration of 50 mg/kg and 250 mg/kg,this practice reduced the effective state copper content.When the four kinds of organic materials were added in the soil with exogenous copper concentration of 250 mg/kg,this practice was the most efficient method to reduce the effective state copper content.Adding the chicken manure in the soil with exogenous copper concentration of 250 mg/kg had the highest reduction effect on the effective state copper content,which followed by sheep manure,the biogas residue,swine manure.When sheep manure was added in the soil with exogenous copper concentration of 500mg/kg,this practice reduced the effective state copper content.The more the amount of sheep manure adding,the greater the effect on the effective state copper content lower.As an organic material were added in the soil,humic acid exerted a negative effect on the copper bioavailability and inhibited chlorophyll to uptake of the copper from the soil.The greater the amount of humic acid,the great inhibiting chlorophyll to copper uptake.When the exogenous copper was 50 mg/kg and humic acid concentration was 6 g/kg and 8 g/kg in the soil,the effect on reducing in chlorophyll to uptake of copper was the greatest.When the humic acid concentration was 6 g/kg in the soil,the copper in chlorophyll dropped by 46%.When the humic acid concentration was 8 g/kg in the soil,the copper in chlorophyll droppedby 46%.Just in the both cases,the copper content in chlorophyll is less than 10 mg/kg,in compliance with state sanitary standard.In terms of concentration of copper in soil,when the exogenous copper was 50 mg/kg in the soil,adding humic acid can reduce the most content of copper in lettuce.Plant rhizosphere leads to reducible state copper increased and oxidizable state copper decreased.The residue state copper content was the highest in the rhizosphere soil,which followed by reducible state copper,oxidizable state copper,acid soluble state copper.The residue state copper content was the highest in the non-rhizosphere soil,which followed by oxidizable state copper,reducible state copper,acid soluble state copper.In the four kinds of organic and inorganic composite materials,the composite materials D,which major constituent is humic acid,brought the most significant negative effects on the copper bioavailability.Compared with control group,when the composite materials D tested in the soil,the copper content in pakchoi decreased by 59%.