Environmental Assessment of Metal Pollution in Manila Bay Surface Sediments

Abstract

The impact of human activities on the sediments of Manila Bay was evaluated through elemental analysis to determine the trace metal element concentration and calculate the corresponding metal enrichment factor (EF). The samples were analyzed using the X-ray tube-excited XRF (X-ray fluorescence) with Ag secondary target to quantify elements Mn to Pb, while the Fe target was used to quantify elements Na to Cr. The radioisotope-excited XRF with 241Am was used for Cd and Hg. The normalized EF has been calculated against baseline values to estimate the environmental impacts of human activity on the bay. In an attempt to provide a better understanding of sediment movement and reworking in the bay, spatial distribution of metals was correlated with the obtained 210Pb radioactivity levels in Manila Bay sediments. Overall, heavy metal and other trace elements are low in Manila Bay sediments, mostly ranging from deficient or minimal to moderate enrichment except for some stations where enrichment of Mn and Cu is significant. Nevertheless, there is a need to estimate the enrichment levels in marine sediments to effectively understand the risk and impact of heavy metals to support management and decision making for the rehabilitation, protection, and maintenance of a healthy ecosystem along the bay.