Determination of Retardation Effect of Soil Organic Matter on Aqueous Leaching of Polycyclic Aromatic Hydrocarbons

Influence of soil organic matter (SOM) on the adsorption, desorption and transport of polycyclic aromatic hydrocarbons (PAHs) has already been given full investigation in soils. In this paper, High Performance Liquid Chromatography (HPLC) was used to detected and elucidate aqueous leaching of PAHs in different types of soil with soil columns, which enhanced understanding on transport of PAHs appreciably. Four typical soils in China including fluvo-aquic soil (FAS), aquic brown soil (ABS), red soil (RS) and black soil (BS) were selected in the experiment. Target pollutants of phenanthrene and pyrene were extracted from the leachate by solid phase extraction (SPE) and then determined HPLC. The experimental results showed that the retardation ability of pollutants to the four selected types of soil increased in the order: FAS ≈ ABS <; RS <; BS. To better expatiate the dissimilar ability of the PAHs transported in the four typical soils, the retardation factor (R), distribution constant (Kd) and partition coefficient (K_oc) were evaluated based on the observed breakthrough curves (BTCs). All the results provided vivid understanding with mathematical and especially optical measures that SOM was considered the single most important factor limiting the availability and mobility of PAHs in soil over the duration of the experiment.