Partitioning and potential sources of polychlorinated naphthalenes in water-sediment system from the Yangtze River Delta, China

Spatial trends, partitioning behavior, and potential sources of polychlorinated naphthalenes (PCNs) in water-sediment system from the Yangtze River Delta (YRD) were investigated in this study. The total concentrations of 75 PCNs in water and sediment samples were 0.022-0.310 ng/L and 0.01-1.59 ng/g dry weight, respectively. The homolog patterns in the sediment and water samples were somewhat different. Di-to tetra-CNs made larger contributions in the sediment, while the mono-to tri-CNs were dominant homologs in the water. Overall, the low-chlorinated naphthalenes (mono-to tetra-CNs) were found to be the dominant homologs in the YRD water and sediment samples, and the homolog group contributions to the total PCNs concentrations decreased as the number of chlorine atoms increased. CN-5/7 and CN-24/14 were found at high concentrations in both the water and sediment. Partitioning and transfer of PCNs between water and sediment were assessed by calculating the partition coefficients and fugacity fractions. The partition coefficients showed that PCNs were not in equilibrium status in the water-sediment system, and hydrophobicity played an important role in PCNs partitioning. The fugacity fractions indicated that mono-to tri-CNs had stronger tendencies to escape from the sediment into the water, while the high-chlorinated naphthalenes close to equilibrium. Principal component analysis and corre-lation analysis indicated that industrial thermal processes and the use and disposal of products containing PCNs industrial products are sources of PCNs in the YRD water-sediment system.