Heavy metal accumulation in sediments and mangrove forest stems from Surat Thani Provice, Thailand

The concentration of heavy metals in mangrove sediments and stems of some mangrove species in Surat Thani province, Thailand were measured, including essential elements (such as Cu and Zn) and non-essential elements (Pb). Physical-chemical properties (e.g., soil texture, pH, CEC, and OM) were analyzed by using the standard method, while heavy metals were analyzed by using an atomic absorption spectrometer. The results show that the sediment samples, have ranges of measured concentration expressed in mg kg-1 dry weight, as follows: 2.90-13.75 of Cu, 8.15- 25.99 of Pb, and 7.50- 46.43 of Zn, while stem samples 0.001-0.148 μg.g-1 of Cu, 0.10-0.83 μg.g-1 of Pb, and 0.57-9.77 μg.g-1 of Zn. The highest measured heavy metal values were found in Sonneratia caseolaris and Avicennia alba. The average value of heavy metals accumulated in the stems and sediments of some species were found to have significant positive correlations and some statistically non-significant (p< 0.05) correlations of heavy metal concentrations (Cu, Pb, and Zn). From this study, it can be concluded that the factors responsible for the accumulation of heavy metal were found to be the organic matter, cation exchange capacity, and the texture of the sediment.