WATER QUALITY AND PERIPHYTIC ALGAE COMMUNITY OF PETANI RIVER BASIN, KEDAH

HAZZEMAN HARIS (2009)

ABSTRACT

This study was carried to determine the status of water quality in the Petani River Basin according to the classification used by the Malaysian Department of Environment (DOE) and to evaluate the reliability of periphyton algae as a biological indicator of water quality. Water samples and periphytic algae were collected from 6 sampling stations with varying level of pollution along the Petani River Basin. Dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), pH and ammonium were measured for the calculation of Water Quality Index (WQI). Parameters such as alkalinity, nitrite, nitrate, orthophosphate, salinity and total dissolved solids (TDS) were also determined. Station B (60.49) recorded the highest WQI, followed by Station F (59.56), Station C (57.13), Station D (56.92), Station E (55.20) and Station A (55.07). This showed that the water quality decreased as it flowed downstream except in Station F. Generally the water quality at Station B where it pass through residential areas and the water in the confluence (Station F) were cleaner as compared to water which flowed through industrial and town centre (Stations C, D, and E). Nutrients such as nitrite, nitrate and ammonium were high in river which flowed through industrial area (Station C), while orthophosphates was high in river which flow through residential and agricultural area (Station A). TSS was high at stations where erosion occurred (Stations A and F). It was found that spring tide has a bigger influence on water physico-chemical properties compared to during neap tide. During spring tide, the increase and decrease of water physico-chemical properties were more obvious throughout the tide cycle as compared to during neap tide. Chlorophyll a and ash-free dry weight (AFDW) were used to calculate autotrophic index (AI), while fine sediment weight (FSW) were determined for the calculation of FSI. High AI in Station C indicates that it was dominated by heterotrophic organisms and had a poor water quality. This was supported by the result of Pearson’s correlation analysis which found that nutrient concentration had a positive relationship with AI. The calculation of Simpson, Shannon-Weiner, Margalef and Menhinick diversity indices had shown Station E and F (brackish) as having the highest species diversity. FSW was also observed to have a positive effect on species diversity. Species such as Climacosphenia moniligera, Closterium sp. and Mischococcus confervicola can only be found in Station C. Thus those species may have a good potential as indicators of nutrient enriched water. The calculation of saprobic index indicated that Station A (1.625) as the most polluted station. This was in agreement with the results obtained through the WQI, thus enhancing the reliability of periphyton as an indicator of water quality.

Masters thesis, Universiti Sains Malaysia.