Physico-chemical assessment of the Jalaur River system, Iloilo, Philippines

Abstract

The Jalaur River System was studied for the quality of its water because water quality is a significant and powerful determinant of the health of aquatic ecosystems. This study aimed at investigating the physico-chemical parameters, nutrient load, heavy metal concentrations and pesticide residues of the Jalaur River system. One of the purposes of this study was to develop a database on the seasonal changes in these river characteristics.

Quantitative samples of water, sediments, algae and fish were collected and analyzed during the rainy season (July-September 2009) and the dry season (January-March 2010) from five sampling stations representing upstream, midstream and downstream sections of the 123-kilometer long river. Based on the water quality standard and water classification adopted by the DENR, the Jalaur River stretch can be classified as class C and D. Class C water is for propagation and growth of aquatic resources while class D water is for agriculture, irrigation, livestock watering, and industrial cooling and processing.

The detected levels of metal contamination, mainly Cr, and Pb, in sediments of Jalaur River were found to exceed the geochemical background or threshold levels. Lead and chromium were also detected in filamentous algae (lumot), <em>Azolla</em>, and tilapia (<em>Oreochromis niloticus</em>) sampled at Moroboro sampling site. No organochlorines, organophosphates, carbamates, and pyrethroids pesticides were detected at the detection limit of the analyses for both water and sediment samples.

The deterioration in the physico-chemical quality and rise in the nutrient levels observed in this study is alarming, and periodic monitoring and preventive measures are required to save the aquatic system of eutrophication. Heavy metal contamination of bottom sediments, algae and fish samples is also a cause for alarm because these heavy metals pose threats to human health. The finidngs have important implications for the development of effective water management strategies and as guide to remediation of efforts for the Jalaur River system.