Distribution and sources of polycyclic aromatic hydrocarbons in the sediment of a sub-tropical coastal wetland

Gene J. Zheng, Ben K.W. Man, James C.W. Lam, Michael H.W. Lam, Paul K.S. Lam

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78 Citations (Scopus)

Abstract

Sediment cores (0-35 cm below surface) from twelve sampling stations in the Mai Po and Inner Deep Bay Ramsar Site of Hong Kong were retrieved in the period March-December 1999. Vertical profiles of 15 priority polycyclic aromatic hydrocarbons (PAHs) in each sediment core were determined. Ranges of total PAH concentration, [ΣPAH], in the wetland sediment were 0.18-0.83 (x̄ = 0.36) μg/g dried sediment (mudflats) and 0.63-0.96 (x̄ = 0.77) μg/g dried sediment (mangroves). A decreasing trend in depth averaged [ΣPAH] was observed from the landward end towards the seaward end of the Marshes. On the mudflats, vertical profiles of the PAHs were quite uniform. At the fringe of the Mai Po mangroves, significantly higher concentration of all PAHs was observed at the upper 0 to -8 cm layer. No significant difference in the distribution patterns of the 15 priority PAHs in summer and winter was observed. This indicates that distribution of PAHs in the sediment of the Mai Po Marshes is not very sensitive to sub-tropical climatic changes of the region. Two PAH isomer ratios, [Phen]/([Phen]+[Anthra]) and [Pyrene]/([Pyrene]+[Fluoran]), were used to identify potential sources of PAH contamination in the wetland. Results revealed that local deposition is a more important source than long-range atmospheric transportation.

Original languageEnglish
Pages (from-to)1457-1468
Number of pages12
JournalWater Research
Volume36
Issue number6
DOIs
Publication statusPublished - 2002
Externally publishedYes

Keywords

  • Coastal wetlands
  • Hong Kong
  • Mai Po
  • PAHs
  • Sediment

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