Influence Of Dissolved Organic Matter On The Biotoxicity Of Phenanthrene

Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants (POPs) widely existing in the environment. They are a unique class of pollutants which are constituted by hundreds of individual substances. These compounds contain two or more fused aromatic rings made up of carbon and hydrogen atoms. PAHs have received popular and environmental attention due to their strongly recalcitrant degradability and the carcinogenic, mutagenic and tumorigenic properties. Dissolved organic matter (DOM), one of the most active chemical components in terrestrial and water ecosystem, is ubiquitous in soil and aqueous environment. It has a great effect on the solubility, adsorption-desorption equilibrium, biodegradation and translocation of organic pollutants in soil and water. Increasing attention has been paid on influence of DOM on environmental behavior of PAHs, especially in soil-plant ecosystem. It has become an interdisciplinary focus in the fields of soil science, ecology and environmental science due to the important roles of DOM in PAHs uptake by plant, PAHs translocation in soils and waters, and PAHs bioremediation in soils. Consequently, this study was carried out to explore the influence of DOM derived from sewage sludge, pig manure and green manure on the biotoxicity of phenanthrene (Phe) in soil-plant ecosystem and the associated mechanism.Adopting biological culture experiments, the biotoxicity of phenanthrene (Phe) and pyrene (Pye) of wheat added in soil was studied. The results showed that there was a significant negative relationship between germination index and concentration of Phe and Pye (r_Phe=-0.9708, r_Pyr=-0.9714), a significant positive relationship between inhabitation rates of root elongation and concentration of Phe and Pye (r_Phe=0.9705, r_Pyr=0.9752). The sensitive range of inhibiting wheat root elongation was from 0 to 200mg/kg for Phe and from 0 to 300mg/kg for Pyr. The media half inhibition concentraton (IC₅₀) was 200mg/kg for Phe and 500mg/kg for Pyr. The biotoxicity of PAHs increased with the increase of its solubility and decrease of the benzene ring number. PAHs could reduce the soil water potential and the degree for this reduction increased with the increase of the solubility of...