Release Of Polycyclic Aromatic Hydrocarbons During The Resuspension Of Sediments From Yellow River In Henan Section

Polycyclic aromatic hydrocarbons (PAHs), ubiquitous environmental pollutants, are known to becarcinogenic, mutagenic and toxic. Due to their low water solubility and high hydrophobicity, onceintroduced into aquatic environment, PAHs rapidly sorb onto particles and subsequently deposit insediments. In such a way sediments become a huge sink for PAHs. During sediment resuspension, thepotential exists for PAHs to be released from sediments into water. Sediment resuspension play animportant role in the transportation and fate of PAHs in the aquatic environment. In this study, thebioavailability of PAHs and the release behavior of PAHs during Yellow River sediment resuspension wasboth investigated using XAD-2resin and a particle entrainment simulatior (PES), based on the analysis ofPAHs in core and fractionated sediments.Results indicated that PAHs concentrations varied largely among different fractions, but thecomposition of PAHs in the each size fraction showed similar patterns dominated by the3~4-ring-PAHswhich contributed more than50%of the∑PAHs. Particle size and density had certain influence onperformance of adsorption, but the distribution of PAHs did not correlate with surface area and porosity.TOC and BC were not efficient adsorbents of∑PAHs in Jiaozuo sediments, but were good adsorbents ofnaphthalene in bulk sediment and heavy component, especially the BC. In Kaifeng sediments, TOC and BCwere not efficient adsorbents of∑PAHs in bulk sediment and heavy component. But in the lightcomponent, both∑PAHs and naphthalene were correlated to TOC and BC. TOC and BC, especially theBC, were the efficient absorbents in small-size (<63μm) light fractions.The release of PAHs into overlying water followed first-order reaction kinetics. The release rateconstants for the initial phase (0~1d) were greater than those for the second phase (1d~6m) and the releaserate constants of23ring PAHs were greater than those of4-ring PAHs. The correlation analysis betweenrelease rate constants and sediment characteristics demonstrated that a lot of factors regulated release ofPAHs during sediment resuspension and the bioavailability.The concerntration of PAHs in the sediment affected the the release of PAHs during resuspensiona lot. The sediment which comprised more PAHs released more PAHs during the resuspension. The absorbent the sediment contained also played an important role for the dissolved concentration of PAHsduring the resuspension.With applied shear increasing, dissolved∑PAHs into the overlying water increased, it due to thedissolved3~4-ring PAHs. Concentrations in TSS on volume normalization increased as applied shearincreased. However, on.mass weight basis,∑PAHs concentrations decreased.