| With the rapid development of economy, soil pollution has become a global environmental problem in recent years. High-molecular-weight polycyclic aromatic hydrocarbons(HMW-PAHs) has been paid enough attention due to potential carcinogenicity, mutagenicity, teratogenicity as well as the ability to be absorbed strongly to soil particles. The previous studies found that 89% of soil samples of agricultural topsoil in coal mining area of Hebei, China were considered to be contaminated with HMW-PAHs. This is a very serious situation about soil pollution with HMW-PAHs. So it is very urgent to remediate these contaminated soils. The combination of Microbial biodegradation and phytoremediation was taken as an efficient way because of less investment, no secondary pollution and its application prospect is very broad in soil pollution remediation. Therefore, this study mainly foucus on PAHs contaminated agricultural soils in a typical coal mine area of Hebei and carried out a pot experiment in greenhouse in order to explore the degradation of soil five and six rings PAHs by Fusarium. sp ZH-H2, a highly effieient degrading strain isolated from the polluted sites. The main results are shown as follows:1. Through enrichment, separation,purification and domestication,the strain with named ZH-H2 was newly isolated from a typical coal mining area of Hebei, which was preliminarily identified as Fusarium and it could degrade individual HMW-PAHs as sole carbon source.2. Strain ZH-H2 could degrade individual HMW-PAHs in mineral medium, such as BKF, Db A, Ba P, Bghip and In P used as the sole carbon and energy, with degrading percentage of 38.19%~91.48%. The removal rate of BKF(91.48%) was significantly greater than Db A, Ba P, Bghip and In P. However, the strain could just degrade 33%~48% of individual HMW-PAHs with the presence of 5 HMW-PAHs mixture in solution. It demonstrated that the extent of degradation on BKF was found to be obviously limited with the presence of five HMW-PAHs together in comparison with that when these PAHs was present alone. The degradation experiment with the added starch were also carried out to enhance the removal of HMW-PAHs in laboratory tests. Total bioremediation percentage of 5 HMW-PAHs mixture by ZH-H2 was improved about 98% in the presence of starch.3. In this paper, we used ZH-H2 and starch to degrade 6 HMW-PAHs in the soil of coal mining area. With the increase of strain inoculation, the removal rate of total 6 kinds of HMW-PAHs showed the increase trend,especially the removal rate was better for 6-rings PAHs than for 5-rings PAHs. The degradation percent of 6-rings PAHs reached the highest level(30.89%) when the amount of strain inoculation reached 1g/kg. At the same time, the added starch also improved the degradation rate of HMW-PAHs significantly. It was analyzed that the coexist of strain inoculation and starch has synergistic effect on the bioremediation of 6 HMW-PAHs in the soil. When the content of soil starch reached 0.25g/kg and the amount of ZH-H2 inoculation was 0.5g/kg, the total removal rate of 6 kinds of HMW-PAHs reached the highest level with 54.10%.4. The present study indicated that the degradation rate of soil 6 HMW-PAHs by the coexist of starch(0.25g/kg)-alfalfa-ZH-H2 was superior to these treatments of ZH-H2, starch, alfalfa as well as coexist of starch and ZH-H2. Meanwhile, when the content of starch was 0.25g/kg and ZH-H2 was 0.5 g/kg, the removal rate of 6 individual HMW-PAHs with the combination of starch, alfalfa and ZH-H2 was highest, reaching 71.88%、66.42%、65.91%,respectively, and the removal rate of total 6 kinds of HMW-PAHs reached 52.38%. Therefore,this coexist treatment was the best conduct for the remediation of HMW-PAHs in the contaminated agricultural soil in the coal mining area.5.The results suggested soil lignin peroxidase activity increased with the increase of starch content and ZH-H2 inoculation amount and the effect was obvious when starch and ZH-H2 were in coexist in soil. The activity of ascorbic oxidase, peroxidase and lignin peroxidase increased greatly when starch, ZH-H2 and alfalfa was coexisted, which could has a direct relationship with high removal rate of 5, 6-rings PAHs in soil. However, the contribution of absorption for HMW-PAHs by alfalfa was just 0.01%~0.83%. |
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