Spatial variation of heavy metals in surface sediments of Hong Kong mangrove swamps

N. F.Y. Tam, Y. S. Wong

Research output: Contribution to journalArticlepeer-review

586 Citations (Scopus)

Abstract

The degree of heavy metal contamination in the fine-grained (<63 μm) and sand-sized (2 mm-63 μm) fractions of surface sediments in 18 different mangrove swamps (144 random samples) in Hong Kong was examined. Higher concentrations of heavy metals were found in the fine-grained than the sand-sized fractions of the sediment; however, the differences between these two fractions became less significant when the swamp was more contaminated. The principal component analyses show that the 18 mangrove swamps, according to the median concentrations of total heavy metals, were clustered into four groups. The first group included three mangrove swamps in Deep Bay region which are seriously contaminated, with heavy metal concentrations in sediments around 80 μg g-1 Cu, 240 μg g-1 Zn, 40 μg g-1 Cr, 30 μg g-1 Ni, 3 μg g-1 Cd and 80 μg g-1 Pb. The second cluster, made up of another four swamps distributed in different geographical locations (two in Sai Kung district and two in Tolo region), also had elevated levels of Cu, Pb, Ni and Cr in the sediments. Field observation reveals that these seven stands received industrial, livestock and domestic sewage as well as pollution from mariculture activities, suggesting that anthropogenic input is the main source of heavy metal contamination in Hong Kong mangroves. The sediments from other mangrove swamps were relatively uncontaminated. Copyright (C) 2000 Elsevier Science Ltd.

Original languageEnglish
Pages (from-to)195-205
Number of pages11
JournalEnvironmental Pollution
Volume110
Issue number2
DOIs
Publication statusPublished - Nov 2000
Externally publishedYes

Keywords

  • Fine-grained fraction
  • Mangroves
  • Metal contamination
  • Principal component analysis
  • Sand sized

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