Degradation of Benzo[a]Pyrene in Soil with Arbuscular Mycorrhizal Alfalfa

Abstract

Mycorrhizal and non-mycorrhizal alfalfa (Medicago sativa) was grown in pots containing soil artificially contaminated with various levels of benzo[a]pyrene (B[a]P) (0, 1, 10 and 100 mg kg )1 ). Soil and plants were sampled after 30, 40, 50, 60 and 90 days and compared with unlanted pots. The percentage of mycorrhizal root length colonized by Glomus caledoniun was not significantly affected by the addition of B[a]P up to 10 mg kg )1 but was significantly lower at 100 mg kg )1 B[a]P compared with low concentrations (p < 0.05). There was no difference in soil polyphenol oxidase and dehydrogenase activity among the controls and applications of 1 and 10 mg kg )1 of B[a]P. However, enzyme activities were significantly higher at 100 mg kg )1 B[a]P compared with the other three treatments, and there was no mycorrhizal effect. Over a period of 90 days the concentration of B[a]P in soil in which alfalfa was grown was significantly lower than in unplanted soil (p < 0.05). Degradation rates of B[a]P added at 1, 10 and 100 mg kg )1 without G. caledonium were 76, 78 and 53%, and with mycorrhizal inoculation were 86, 87 and 57%. The degradation rate in unplanted soil was significantly lower than in planted soil, and was significantly higher in medium-and low-B[a]P treatments than in the high B[a]P concentration tested. There is a possibility of enhancement phytoremediation of PAHs in rhizosphere soil with arbuscular mycorrhizal fungi.

Phenanthrene toxicity and dissipation in rhizosphere of grassland plants (Lolium perenne L. and Trifolium pratense L.) in three spiked soils

“…A drastic negative phenanthrene effect on the mycorrhization of ryegrass and red clover was quantified. Similar results have been found in several studies such as the negative benzo(a)pyrene effect on the alfalfa mycorrhization (Liu et al 2004). On the contrary, the colonisation of red clover by Rhizobium was stimulated by the presence of phenanthrene.…”

In situ phytoremediation of PAH-contaminated soil by intercropping alfalfa (Medicago sativa L.) with tall fescue (Festuca arundinacea Schreb.) and associated soil microbial activity

“…Parrish et al (2004) reported 24% dissipation of total PAHs in composted soil in the presence of tall fescue. Greenhouse experiments have demonstrated enhanced removal of PAHs when alfalfa was planted compared with unplanted controls (Liu et al 2004). These results were obtained using single plant species and little is known about how plant species and cropping patterns affect the processes by which phytoremediation removes PAHs on a field scale (Meng et al 2011;Wei and Pan 2010).…”

“…Phytoremediation, the use of plants to remediate contaminated soil, has been described as a promising approach to remediate soils contaminated with persistent organic pollutants such as PAHs (Chen et al 2003;Huang et al 2004;Phillips et al 2009). During the last few decades, numerous plant species including alfalfa and tall fescue have been found to be promising candidates for phytoremediation of PAHs (Liu et al 2004;Parrish et al 2004;Balcom and Crowley 2009). Parrish et al (2004) reported 24% dissipation of total PAHs in composted soil in the presence of tall fescue.…”

Mineralization of pyrene induced by interaction between Ochrobactrum sp. PW and ryegrass in spiked soil

“…It was indicated that PW inoculation was the main reason increased the activity of polyphenol oxidase. And the enhanced polyphenol oxidase activity in RP treatment may contribute to the increasing dissipation of pyrene as polyphenol oxidase can catalyze the degradation and transformation of aromatic compounds (Gramss et al, 1999;Liu et al, 2004). Thus, microbial degradation appears to be the most important approach during the remediation process and plant growth will in turn enhance the microbial growth of both native and introduced strains.…”