| Remediation of oil pollution gets more and more attention with the increased pollution. Bioremediation has become a promising technology to deal with environmental oil pollutants in shoreline, due to its high efficiency,, low cost and ecological sound. The research simulates the oil contaminated intertidal area under laboratory conditions by applying wetland microcosm method and to establish the site bioremediation mode based on nereid-multifuctional group to solve oil pollution problem in coastal tidal wetlands. Analyzing oil degradation effect treated by nereid, suaeda salsa and microorganisms combination by ultra-florescence spectrophotometry reveal the strengthening effect of Nereis bioturbation in Suaeda salsa and oil degradation bacterial joint system, which aims to provide reference and data support for bioremediation in oil contaminated intertidal area. The main results of this research are shown as follows:(1)The optimum condition of the ultrasonic extraction applied in oil pollutioned sediment by orthogonal test was as follows:extracting 2 times, each for 15 min, with dichloromethane, at 30℃,, and liquid / solid ratio reach 6:1. The extraction rates of oil pollution sediment with the concentration of 2%, 1%, 0.5% and 0.1% reached 90.09%, 88.86%, 82.65% and 85.71% respectively, which indicated that this method performes better at high concentration groups compared to lower concentration groups.(2)An chronic toxicity test and wetland microcosm theory were used to establish Nereid,Suaeda salsa, oil degradation bacterial functional group bioremediation mode to remediate oil pollution. Three concentrations of crude oil(500mg/kg, 1500mg/kg and 3000mg/kg) were set and denoted as I, Ⅱand III; and there are four kinds of biological functional models: oil degradation bacterial model(B), nereid and oil degradation bacterial model(NB), suaeda salsa and oil degradation bacterial model(SB) and nereid, suaeda salsa and oil degradation bacterial model(NSB). The results showed that the oil degradation rates of different bioremediation combination models were significantly higher than group C(P<0.05) during the whole experiment time(70 days). The oil degradation rate of NSB model reached 51.91%、47.78% and 40.59% respectively in I,II and III experiments, which have significant difference with NB model and SB model(P<0.05).The degradation rate of NB model and SB model is significantly higher than the B model in II and III experiment sediments(P<0.05);but those three treatments have no significant difference in I experiment(P>0.05) with NB>SB> B model.The oil degradation speed in each bioremediation combination shows an increasing trend in the began month. oil degradation speed in NSB model was significantly higher than any other models with 1.14%/d、1.20%/d and 1.26%/d respectively. The oil degradation vspeed decreased obviously at 30-70 d in all bioremedation models.(3)GC-MS method was used to analyse the degradation rate of normal hydrocarbons, The results showed that the rate of normal hydrocarbons in all bioremedation models reduced distinctly as carbon chain length increases. The degradation rates of each normal hydrocarbon component in NSB model are higher than those of other bioremedation models during the whole experiment. Its average oil degradation rates reached 22.89%(I)、25.12%(II) and 24.02%(III)respectively after 70 days. C model acted poorest, and has significant difference with other bioremedation models(P<0.05),and its degradation rates are positively correlated with sediment oil concentrations. SB model performed better than NB model in type III sediment, their degradation rates are 18.38% and 15.01% respectively. B model degradation rates have negative correlation with oil concentrations in sediment, the degradation rates are 15.65%,13.81% and 10.04% respectively in three concentration groups.(4)Degradation of PAHs in each bioremedation model decreased with the number of rings increases. NSB model and B model is respectively the best and the worst bioremediation model, former’s average PAHs degradation rate reached 54.93%(I),59.53%(II) and 47.68%(III) respectively in in three concentration groups after 70 days. The average PAHs degradation rate in NB model was higher than that in SB model in I group, but the rates in NB model were lower than that in SB model in other two groups, the average degradations of these two models in three groups were 49.12%,50.08%,38.19% and 45.04%,52.77%,41.45% respectively. The average degradations rate in Control group were 9.37%,13.93% and 19.00% respectively, which have significant differences with all bioremedation models(P<0.05). |
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