Rapid Oxygen Depletion and High Phosphorus Content Indicate Pollution of Lahug River, Cebu City, Philippines

Abstract

The present study deals with the physico-chemical analysis of water samplescollected monthly from three established sites in Lahug River for a period ofsix months. The main purpose of the study is to provide baseline data on itsphysico-chemical characteristics as well as assess its water quality. Statistical toolswere used to analyze and interpret the data. The pH, temperature, TDS, DO, nitrates and total P varied significantly (p<0.05) across location. The pH valuesvaried from 7.2 to 7.7 are suitable for the largest variety of aquatic organisms.Water temperature, total suspended solids (TSS), total dissolved solids (TDS) and levels of nitrates were within the permissible DENR guidelines for Class D surface waters. However, the levels of dissolved oxygen (DO), biochemicaloxygen demand (BOD) and total P did not comply with the DENR Class Dstandard for surface waters. Rapid oxygen depletion and high phosphorus contentas it traversed downstream indicated that the river is polluted. Major sourcesof pollution were found to be anthropogenic activities such as indiscriminatedumping of refuse, disposal of waste water from laundry and piggery, and waterflow from backyard gardening which uses pesticides or fertilizers. Proper disposalof wastes, establishment of waste water treatment measures, education and publicenvironmental awareness should be done at the community level to reduce thelevel of pollution in Lahug River.Keywords: Aquatic Ecology, water quality, rivers, physico-chemical parameter, descriptivedesign, Philippines