A preliminary assessment of heavy metals in sediments from the Cipero and South Oropouche Rivers in Trinidad, West Indies.

The increasing urbanization and industrial processes in Trinidad within recent years could pose a possible contamination threat to the aquatic environment. The southwestern part of the island houses numerous industrial activities, and the recent sightings of schools of dead fish and other marine organisms in that locality is cause for concern prompting research into this occurrence. Sediment and surface water samples from the Cipero and South Oropouche Rivers in South Trinidad were analyzed for their heavy metal content (Cd, Cr, Cu, Mn, Ni, Pb, and Zn). Another watercourse, the Moruga River, was selected as a control, based on its location away from significant anthropogenic sources, and the levels of heavy metals obtained for this location were considered as background concentrations for both surface waters and sediments. Cadmium, Ni, and Pb were not detected in surface water samples of both rivers. The corresponding order of metals in the Cipero River was Mn > Cr > Zn > Cu, while for the South Oropouche River, the order was Mn > Cr > Cu > Zn. The individual concentrations of metals in sediments found in the Cipero and South Oropouche Rivers varied according to the following orders: Mn > Zn > Cu > Pb > Ni > Cr > Cd and Mn > Zn > Pb > Cu > Ni > Cr > Cd, respectively. Assessments of the pollution status in sediments revealed that the Cipero River was considered polluted with a moderate degree of ecological pollution while the South Oropouche River was also deemed polluted; however, the degree of ecological pollution associated with that river was low. Principal component analysis (PCA) and cluster analysis (CA) confirmed that both anthropogenic and natural sources contributed to heavy metal contamination in sediments of both rivers.