Measurement and behaviour of heavy metals in the marine environment of Singapore
Concentrations of heavy metals were determined in the water column (including the sea-surface microlayer (SML), subsurface, mid-depth and bottom water) and sediments at two sampling sites (Kranji in the northwest, and Pulau Tekong in the northeast of Singapore) with contrasting hydrodynamic characteristics in Singaporea??s coastal environment. To evaluate relative mobility and bioavailability, a further study on the chemical speciation of heavy metals in the marine sediments from the two sampling sites was determined using a modified BCR-sequential extraction procedure. In addition, concentrations of heavy metals in the SML and subsurface water, sediments and biota were measured in two mangrove habitats in Singapore located in the West (Sungei Buloh) and East Johore Strait (Sungei Khatib Bongsu). Overall, in comparison to data from other countries including Greece, Malaysia, USA, the Netherlands, Thailand, Japan, Korea, Spain and China, the levels of metals in the dissolved phase, suspended particulate matter and marine sediments are considered to be low in Singapore. With respect to heavy metal contamination, mangrove habitats in Singapore are less contaminated than those found in Deep Bay, Hong Kong and in Brazil, but more contaminated than those in Australia and Mexico.
Heavy metals, water column, sequential extraction, sediments, mangrove habitats, Southeast Asia.
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