Effects Of Cadmium Xanthate Formation On Soil Microbial Toxicity And Cadmium Speciation In Soil

Flotation chemicals and heavy metals are typical pollutants in non-ferrous metal mines,and their combined pollution is a hotpot in environmental management of non-ferrous metal mines.Isobutyl xanthate is a typical flotation reagent for sulfide ore,and the dosage is extremely large;cadmium is the main associated metal in lead-zinc mines,and is often discharged with excessive amounts of flotation reagents.Cadmium xanthate is the complex formation of xanthate and cadmium,and is an important intermediate substance in the compound pollution of them.This study analyzed the toxicity of single pollutants and composite pollutants and the changes of cadmium migration among single pollutants and compound pollutants based on BCR method,microcalorimetry,and soil enzyme activity analysis.The influence of the formation of compound pollutants on the migration of heavy metals and the toxicity of compound pollution was discussed.The main results are as follows:From the perspective of the form of cadmium,the BCR results show that cadmium xanthate is a stable residue state,but will gradually decompose in the soil.The stability of cadmium xanthate in soil increases with concentration.The decomposition of cadmium xanthate can release cadmium elements with high mobility to soil,and the decomposition products can affect the form of cadmium elements in soil for a long time.In the soil contaminated by high concentration of cadmium in this research,cadmium can maintain high mobility for a long time.From the perspective of soil microbial metabolism heat,cadmium maintains long-term toxic effects on soil microbes.Xanthate is unstable in soil,and the organic matter released by decomposition weakens its toxicity to soil microorganisms to a certain extent.The toxicity of cadmium xanthate is relatively minimal.But with the decomposition of the compound,the release of organic matter and cadmium forms an antagonistic effect.The inhibition rate of three pollutants on soil microbial metabolic activity within 60 days: Cadmium> Xanthate > Cadmium xanthate.Based on the analysis of soil enzyme activity,cadmium showed a significant inhibitory effect on soil enzyme activity.The influence of xanthate on soil enzyme activity is relatively small,and the stimulation effect on soil enzyme appears in different pollution time.Cadmium xanthate can also stimulate enzyme activity,its toxicity to soil enzyme activity is affected by the cadmium and organic matter released by its decomposition.Urease is most sensitive to cadmium xanthate contamination.Compared with the single pollutant,the complex pollutant cadmium xanthate is more stable in soil,and the toxicity is lower.The formation of complex pollutants is the reason why the migration of heavy metals and toxicity reduced in the complex pollution of heavy metals and flotation reagents.However,in the long-term pollution,the mobility of cadmium in cadmium xanthate will be enhanced,which can maintain the toxic effect on soil microorganisms and permanently inhibit the activity of sensitive soil enzymes.