Bioremediation Of Soils Contaminated With Polycyclic Aromatic Hydrocarbons And Its Combination With Cu

Combined soil pollution is a common form of soil pollution today. And the contaminated soils caused by the combination of persistent organic pollutants such as polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HM) have been reported many times in the literature. In this paper, a pot experiment using alfalfa and red clover was conducted to study the effects of phytoremediation on combined pollution soils caused by phenanthrene, pyrene and Cu. Meanwhile, a cultivation experiment with the application of orthogonal experimental design under laboratory conditions was used to study the effects of C/N ratio, C/P ratio of soil available nutrients, soil moisture and incubation time on the bioremediation of soils contaminated by phenanthrene and pyrene. The main results are the following:(1) The removal efficiencies of phenanthrene and pyrene were in the range of 87.8%～95.4% and 65.0%～82.5%, respectively, in the contaminated soils planted with red clover and those were in the range of 90.4%～98% and 74%～91.8%, respectively, for alfalfa. The higher concentrations of phenanthrene and pyrene were in soils, the higher concentrations of phenanthrene and pyrene were in plants. The bioconcentration factors (BCFs) of red clover and alfalfa for phenanthrene and pyrene in roots were greater than those in shoots. Phenanthrene was easier to be transferred than pyrene in plants. The average value of translocation factors(TFs) for phenanthrene and pyrene in red clover were 0.8 and 0.36, respectively, and those in alfalfa were 1.2 and 0.73, respectively. Uptake of phenanthrene and pyrene from soil by alfalfa could be inhibited by Cu application while there was no inhibition for red clover. The content of Cu in roots was higher than that in shoots of red clover and alfalfa.(2) When soil available nutrients C/N ratio and C/P ratio were 20/1 and 100/1, respectively, and soil moisture was 25% of field water holding capacity and incubation time was 60 d, the highest removal rate of phenanthrene could reach up to 99.5%. When soil available nutrients C/N ratio and C/P ratio were 10/1 and 100/0.5, respectively, and soil moisture was 60% of field water holding capacity and incubation time was 60 d, the highest removal rate of phenanthrene could reach up to 94.6%. According to the range analysis in the orthogonal experimental design, it could be inferred that the soil moisture was the main factor affecting the biodegradation of PAHs in soils, followed by the incubation time.