The mercury and cadmium levels in the waters of the two major rivers in Cagayan De Oro City, Philippines

The Cagayan de Oro River and the Iponan River are two major rivers in the City of Cagayan de Oro—a highly urbanized city in the southern part of the Philippines. The waters of these two rivers were monitored at the downstream, midstream, and upstream portions for 8 months to establish the levels of mercury and cadmium. A total of 11 samples have been taken and analyzed for mercury using AAS equipped with a mercury/hydride system and for cadmium using flame AAS. The analysis methods used were validated in terms of detection limit, quantitation limit, signal-to-noise ratio, and percent recovery using USEPA-based procedure. On the average, the mercury for the Cagayan de Oro River came out at a concentration of 0.073 ppb and was highest at the downstream; for the Iponan River, it averaged at 0.067 and was highest at the upstream. The cadmium for the Cagayan de Oro River turned out at 0.048ppm and was uniform throughout; for the Iponan River, it was 0.033ppm and relatively somewhat higher at the upstream. Risk characterization based on the ANZECC guideline trigger values yielded risk quotients that indicated no risk to the two river ecosystems as far as mercury, but an enormous risk is suggested due to cadmium for both river ecosystems. published by the Journal of Biodiversity and Environmental Sciences | JBES