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Abstract: In order to clarify heavy metal concentration profiles in different mangrove forest ages, four sediment cores (up to 100 cm in depth) were collected and tested for their physicochemical characteristics (pH, Eh, organic matters and grain size) and heavy metal concentrations. Results showed that mangrove sediments were composed mainly of sandy silt, silty sand, silt, sandy mud and mud. The average mud content in the sediment cores continuously increased with mangrove forest ages from one, nine, nineteen and twenty years old, whereas the mud content highly fluctuated with the core depth. pH, Eh and organic matter content implied that the sedimentary depositional environments were classified as weak alkaline and anaerobic. The Cu and Zn concentrations in the sediment cores from the intertidal zone exceeded the TEL values in Canadian Interim Marine Sediment Quality Guideline (ISQGs) values, while, Pb concentration exceeded the PEL level. When compared with National Technical Regulation on Sediment Quality QCVN43:2012/BTNMT, sediment samples were polluted by Cu and Pb.
Keywords: Mangrove sediments, heavy metals, intertidal, Da Loc.
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