Influence Of Integrated Remediation On The Microbial Properties And Enzyme Activities Of Cu, Cd Contaminated Soil

The experiment was an in situ integrated remediation of a soil contaminated by copper and cadmium. The experiment was conducted in Miaoyunao Village,Daye Country,Hubei province, China. Due to mining activities, this area was heavily contaminated by cadmium and slightly by copper. Lettuce was selected as experimental plant species. Rice straw(10.3t ha-1and23.2t ha-1),engineered bacteria(X4/pCIM:108CFU g-1and5x108CFU g-1), lime(1.35t ha-1and2.03t ha-1) were selected as integrated remediation materials. When harvest lettuce, rhizosphere and non-rhizosphere soil were collected separately. It was investigated that the influence of in suit stabilization remediation on soil microbial and biochemistry properties. The main results are outlined as follows:1.Application of rice straw, engineered bacteria and lime significantly increase MBC in rhizosphere and non-rhizosphere soil. Rice straw treatment increased MBC by0.70%-25.39%in non-rhizosphere soil. High amount rice straw and engineered bacteria treatment increased MBC by14.38-50.41%and0.18%-16.88%in non-rhizosphere and rhizosphere soil. High amount rice straw, high amount engineered bacteria and lime treatment increased MBC by19.69-60.44%and10.19%-34.30%in non-rhizosphere and rhizosphere soil.2.Application of rice straw, engineered bacteria and lime significantly increase culturable actinomycete, fungi in rhizosphere and non-rhizosphere soil. Low amount rice straw respectively increased by19.17%and19.19%in non-rhizosphere and rhizosphere soil. High amount rice straw increased actinomycete by47.70%in non-rhizosphere soil. High amount rice straw and low amount engineered bacteria increased actinomycete by18.98%in rhizosphere soil. High amount rice straw, high amount engineered bacteria and low amount lime increased actinomycete by33.23%in non-rhizosphere soil. High amount rice straw, high amount engineered bacteria and high amount lime respectively increased by62.06%and60.78%in non-rhizosphere and rhizosphere soil. Rice straw treatment increased fungi by82.23%-145.77%and162.08%-539.11%in non-rhizosphere and rhizosphere soil, high amount rice straw and engineered bacteria increased fungi by46.39%-46.60%and240.68%-450.50%in non-rhizosphere and rhizosphere soil. High amount rice straw, high amount engineered bacteria and lime increased fungi by125.29%-142.84%and348.04%-453.13%in non-rhizosphere and rhizosphere soil. Low amount rice straw increase bacteria by17.55%in rhizosphere soil, high amount rice straw increase bacteria by6.46%in non-rhizosphere soil. High amount rice straw and engineered bacteria increased bacteria by1.15%-2.73%in rhizosphere.3. Application of rice straw, engineered bacteria and lime significantly increase urease and catalase activities in rhizosphere soil and catalase activity in non-rhizospere soil. High amount rice straw increase invertase activity by55.86%in non-rhizospere soil, High amount rice straw and low amount engineered bacteria increase invertase activity by15.05%in non-rhizospere soil, High amount rice straw, high amount engineered bacteria and high amount lime increase invertase activity by14.21%and18.71%in non-rhizosphere and rhizosphere soil. Low amount rice straw increase urease activity by33.87%in rhizosphere soil, high amount rice straw increase urease activity by55%and174.81%in non-rhizosphere and rhizosphere soil, high amount rice straw and engineered bacteria increase urease activity by0.96%-14.85%in rhizosphere soil. high amount rice straw, high amount engineered bacteria and low amount lime increase urease activity by42.56%and173.24%in non-rhizosphere and rhizosphere soil. high amount rice straw, high amount engineered bacteria and high amount lime increase urease activity by204.60%in rhizosphere soil. Low amount rice straw increase catalase activity by6.90%in non-rhizosphere soil. High amount rice straw increased catalase activity by41.38%and2.38%in non-rhizosphere and rhizosphere soil. High amount rice straw and engineered bacteria increase catalase activity by37.93%-41.38%and7.14%-19.05%in non-rhizosphere and rhizosphere soil. High amount rice straw, high amount engineered bacteriaand lime increased catalase activity by24.14%-44.83%and2.38%-11.90%in non-rhizosphere and rhizosphere soil.4.Correlation coefficients between soil enzyme activities and soil microbial population were calculated. Positive correlations were found between MBC and fungi, actinomycete. Fungi was correlated with urease and catalase activities. Invertase activity was correlated with bacteria and actinomycetes.5. The DGGE results show that the integrated remediation have more influence on the rhizosphere soil microbial diversity,compare to non-rhizosphere soil.