Oil - Passivation Of Heavy Metals Contamination Of Heavy Metals In Saline Soil Biological Complex In MCB

At present, along with the increased of oil production and consumption, the oilwill inevitably enter the soil environment, resulting in oil contaminated soil. Andthrough the analysis of Gudao oil pollution of salinization soil in the Yellow Riverdelta, we find that the soil is more seriously polluted by the heavy metals, caused oil-heavy metals. In a general way, oil contaminated soil use bioremediation technologythat is low cost, no-two pollution. But in the degradation process of heavy metals inthe oil will be activated, thus affecting the oil degradation rate, so it is necessary topassivate the activated heavy metals. But most of the oil-heavy metals pollution ofsoil is the saline soil, the general passivator is very difficult to play a role. And thenano-carbon black because of its unique physicochemical properties, such as immensespecific surface area, high activity level, strong adsorption, catalysis and chelatingability, has a broad application prospect in the environmental pollution control field.In this paper, the contaminated saline soil of simulation Cd、Ni, adding modifiednano-carbon black, by culture experiment, the paper analysis of the characteristics ofsoil pH、available heavy metals and distinction variation of heavy metals to studythe passivation ability of modified nano-carbon black (MCB) for heavy metals. Bysimulating oil-heavy metals contamination in saline soil, using of pot experiments,the paper analyzes soil pH、available heavy metals、metals speciation、oil degradationand so on and studies passivation capability of heavy metals by modified nano-carbonblack during microbial remediation of oil-heavy metals contamination in saline soiland plants-microbial remediation process modified nano-carbon black in saline soil.The major objective of the present study is to provide some theoretical proofs of thepassivation capability of heavy metals by modified nano-carbon black in oil-heavymetals contaminated soil.The main results are as follows:When the saline soil is polluted by heavy metals, the pH of soil will decreaseafter the addition of MCB. In the every cultivation time, the available Cd content inaddition MCB soil is lower than those of the corresponding without MCB treatment; but the available Ni content in addition MCB soil and corresponding without MCBtreatment shows a change ups and downs. The morphology of Cd、 Ni in soil issignificantly changed by adding MCB. After35days, the weak acid extractablecontent of Cd is decreased and reducible content of Cd is changed little; the weak acidextractable content of Ni is decreased, oxidation state content is increased, reductionstate content is not obvious regularity.During oil-heavy metals pollution in soil by bioremediation, the pH of soil isdecreased along with culture time, and the pH of without addition MCB treatment isdecreased more than with MCB treatment. After35days, the pH is stabilized. Heavymetals Cd、 Ni are activated during the process of microbial degradation oil; theaddition of MCB can significantly decrease the content of available Cd、 Ni. Thisshows that MCB has good effect on the passivation of Cd and Ni, and the passivationeffect of MCB on Cd is better than the effect on Ni. The form of Cd、Ni are changedby addition of MCB. After60days, the oxidation state and the reduction state contentof heavy metals in addition MCB are decreased. Biodegradation rate is below15%byindigenous bacteria, but the biodegradation rate reaches45%by adding oildecomposing bacteria. There is not effect in degradation of petroleum hydrocarbon byaddition of MCB in soil.By plant-microbial remediation in oil-heavy metals pollution soil, the addition ofMCB can reduce the pH of soil and promote the growth of Suaeda salsa. The biomassof Suaeda salsa in oil-heavy metals polluted soil is significantly lower than that ofsingle oil contaminated soil. Regardless of adding MCB or not, the biomass of Suaedasalsa in adding oil decomposing bacteria is lower than the treatment without addingoil decomposing bacteria. The addition of MCB can significantly reduce theavailability of heavy metals in soil. The passivation ability of MCB in heavy metalsby plant-microbial remediation is better than that of just plant repair. The weak acidextractable state、reduction state、oxidation state of Cd are respectively decreased19%,61%,82%by addition of MCB into soil， and the weak acid extractable state、reduction state、oxidation state of Cd are respectively decreased15%,42%and5%.By plant-microbial remediation in oil-heavy metals pollution soil, adding MCB can promote the enrichment of Cd、Ni in Suaeda salsa, and the enrichment effect ofplant-microbial remediation is more obvious than only phytoremediation in oil-Cdcontaminated soil. The enrichment effect of plant-microbial remediation is notdifference than only phytoremediation in oil-Ni contaminated soil. After the harvest ofSuaeda salsa, the degradation rate of petroleum hydrocarbon are significantlyincreased by addition oil decomposing bacteria; and the degradation rate of petroleumhydrocarbon of addition MCB in soil is slightly higher than that in the treatmentwithout MCB, which indicating that addition MCB has little effect on thebiodegradation of petroleum degrading bacteria.