Remediation of soil polluted with HMW-PAHs by alfalfa or brome in combination with fungi and starch.

High-molecular weight polycyclic aromatic hydrocarbons (HMW-PAHs) are common pollutants in soil of coal mining areas that affect the safety of crops and the environment. In a pot experiment, we compared the remediation potential of alfalfa (Medicago sativa Linn) and brome (Bromus inermis Leyss.) either alone or in combination with starch or Fusarium sp. strain ZH-H2 for a farmland soil contaminated with 4-6-ring PAHs from a coal mine area. The alfalfa and brome alone treatments reduced the concentrations of most HMW-PAHs. However, when starch was added, the removal rates of indeno(1,2,3-cd)pyrene and benzo(ghi)perylene were significantly higher for brome than for alfalfa. When ZH-H2 was combined with brome, benzo(k)fluoranthene, benzo(a)pyrene, indeno(1,2,3-cd)pyrene, and benzo(ghi)perylene degradation rates were significantly enhanced compared with brome alone. In contrast, an antagonistic effect was observed between alfalfa and Fusarium. The brome, starch and ZH-H2 combination resulted in far better removal rates than the alfalfa combination. Maximum removal rates were obtained with the brome + starch + ZH-H2 combination for benzo(k)fluoranthene (42.64%), benzo(a)pyrene (51.01%), indeno(1,2,3-cd)pyrene (62.29%), and benzo(ghi)perylene (74.85%). These removal rates were 829.78%, 182.34%, 46.13%, and 70.94% higher than the equivalent alfalfa combination treatments. The lignin peroxidase activity was significantly increased in the presence of starch, ZH-H2 and brome, consistent with the increased removal rates of HMW-PAHs.

Starch-enhanced degradation of HMW PAHs by Fusarium sp. in an aged polluted soil from a coal mining area.

The present study used strain ZH-H2 (Fusarium sp.) isolated by our group as the PAH-degrading strain and 5-6-rings PAHs as degradation objects. The soil incubation experiment was carried out to investigate the starch-enhanced degradation effects of HMW PAHs by Fusarium sp. in an Aged Polluted Soil from a Coal Mining Area. The results showed that the removal rates of BaP, InP and BghiP increased with increasing inoculation rate of ZH-H2 in the unsterile aged polluted soil of coal mining area, with the exception of BbF degradation which increased in the H2 treatment and then decreased. Different addition dosage of starch apparently resulted in degradation of 4 PAHs in soil, with removal rates of 14.47% for BaP, 23.83% for DbA, 30.77% for BghiP and 31.00% for InP obtained with treatment D2, respectively higher than in treatment D1. So starch addition apparently enhanced the degradation of the 4 PAHs, especially InP and BghiP, by native microbes in the aged HMW PAH-polluted soil. By adding starch to these aged polluted soils with inoculated strain ZH-H2, HMW-PAHs degradation was further improved and addition of 0.5 g kg-1 starch to soils with 1.0 g kg-1 Fusarium ZH-H2 (D2 + H2) performed best to the 4 HMW-PAHs in all of these combination treatments by a factor of up to 3.09, depending on the PAH. We found that the highest polyphenol oxidase activities under D2 + H2 treatments are consistent with the results of removal rates of 4 PAHs. Our findings suggest that the combination of Fusarium sp. ZH-H2 and starch offers a suitable alternative for bioremediation of aged PAH-contaminated soil in coal mining areas, with a recommended inoculation size of 0.5 g Fusarium sp. ZH-H2 and addition of 0.5 g kg-1 starch per kg soil.