Abstract
Pot experiments were conducted to evaluate plant contribution during remediation of the polycyclic aromatic hydrocarbons (PAH)-contaminated soil of Dagang Oilfield by Fire Phoenix (a mixture of Festuca L.). The results showed that Fire Phoenix could grow in soil contaminated by high and low concentrations of PAHs. After being planted for 150days, the total removal rate of six PAHs in the high and low PAH concentrations was 80.36% and 79.79%, significantly higher than the 58.79% and 53.29% of the unplanted control group, respectively. Thus, Fire Phoenix can effectively repair the soil contaminated by different concentrations of PAHs. In high concentrations of PAHs, the results indicated a positive linear relationship between PAH absorption in tissues of Fire Phoenix and the growth time in the early stage. In contrast, the contents of PAHs were just slightly increased in the late period of plant growth. The main factor for the dissipation of PAHs was plant-promoted biodegradation (99.04%-99.93%), suggesting a low contribution of PAH uptake and transformation (0.07%-0.96%). The results revealed that Fire Phoenix did not remove the PAHs in the soil by accumulation but promoted PAH dissipation in the soil by stimulating the microbial metabolism in the rhizosphere.
Highlights
Polycyclic aromatic hydrocarbons (PAHs) refer to condensed ring compounds in which two or more benzene rings are arranged in linear, angular, or clustered shapes
The present study showed that Fire Phoenix plants could grow in soil contaminated by high and low PAH concentrations
The total removal rates of the six PAHs in the high and low PAH concentrations were 80.36% and 79.79%, significantly higher than the 58.79% and 53.29% of the unplanted control group, respectively
Summary
Polycyclic aromatic hydrocarbons (PAHs) refer to condensed ring compounds in which two or more benzene rings are arranged in linear, angular, or clustered shapes. They have the characteristics of hydrophobicity, low vapor pressure, and high octanol-water partition coefficient (Rey-Salgueiro et al 2008; Haritash and Kaushik 2009; Venny et al 2012; Bezza and Chirwa 2017). PAHs are preferentially distributed to non-aqueous systems They are strongly adsorbent in soil, sediment, and solids in water (Congiu and Ortega-Calvo 2014) and do not degrade under natural conditions. The binding force between soil and PAHs varies from simple adsorption to covalent binding (Haritash and Kaushik 2009; Venny et al 2012), challenging the development of PAH removal technology in the soil
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