Abstract

The distribution and historical changes of polycyclic aromatic hydrocarbons (PAHs) contamination in mangrove sediments in Hong Kong SAR were investigated. Surface sediments (2–3 cm) collected from four mangrove swamps exhibited significant spatial variations in concentrations of total PAH (with ∑PAHs ranging from 56 to 3758 ng g −1 dry wt), as well as the composition of 16 USEPA priority PAH compounds. Within a small swamp with an area of 0.68 ha, the total PAH concentrations also differed from sampling site to site, indicating that the PAH contamination is localized and confined to a very small area within the same swamp. Discharges from municipal and industrial wastewater, urban runoff, oil leakage from boats and ships, and accidental oil spill are possible sources of the PAH contamination. The sediment depth profiles reveal that the surface sediment layer (0–5 cm) had lower total PAH concentrations than that in the bottom layer (15–20 cm), and PAH composition also changed with the sediment layers. Based on the estimated annual sediment deposition rate in Hong Kong SAR of around 0.4–0.5 cm, the present findings suggest that the PAH contamination was most serious between 1958 and 1979 but started to decline thereafter. Such decline was probably due to changes in petroleum usage in urban areas and a better control of wastewater discharges from 1980 onwards in this region.

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.