Distribution and Pollution Assessment of Heavy Metals in Surface Sediments From Prawet Burirom Canal, Bangkok, Thailand

This research investigated the spatial distribution and levels of heavy metal contamination in sediments along the Prawet Burirom Canal, Ladkrabang District, Bangkok, Thailand. Surface sediment samples were collected from the bottom of the canal between Wat Ratchakosa and Wat Lat Krabang on August 29, 2025. The samples were prepared for elemental analysis via microwave-assisted acid digestion and measured by ICP-OES. The mean concentrations of heavy metals in the sediments in decreasing order of contamination were: iron (Fe) > manganese (Mn) > zinc (Zn) > copper (Cu) > arsenic (As) > chromium (Cr) > lead (Pb) > cobalt (Co). Their ranges were determined to be 50.81-66.94 g/kg for Fe, 361.04-690.49 mg/kg for Mn, 71.26-198.41 mg/kg for Zn, 44.15-67.14 mg/kg for Cu, 15.28-84.56 mg/kg for As, 32.28-47.49 mg/kg for Cr, 17.87-47.32 mg/kg for Pb, and 8.26-11.75 mg/kg for Co, while cadmium (Cd) and nickel (Ni) were not detected. Five toxic metals, As, Pb, Cr, Zn and Cu, were used to evaluate pollution and ecological risk assessments. Based on the geo-accumulation index (I_geo), the sediments were classified as extremely contaminated with Pb and heavily to extremely contaminated with As. The contamination factors (CF) for As, Zn, and Cu indicated very high contamination while the pollution load index (PLI) displays a gradual decline in site quality. The overall ecological risk was categorized as considerable to high ecological risk. This study suggests that the high contamination levels of heavy metals, particularly As and Pb, were frequently related to anthropogenic activities in the surrounding environment.