ASSESSMENT OF SURFACE WATER QUALITY OF THAKURGAON SADAR UPAZILA FOR IRRIGATION AND FISH PRODUCTION

Abstract

Surface water samples (60 ponds and 10 samples from two rivers in different sampling sites) collected from the Thakugaon Sadar Upazilla, Thakurgaon, Bangladesh in dry season of the year 2012 and analyzed for its quality and suitability for agricultural and aquatic purposes. Analyses included pH, EC, temperature, dissolved oxygen (DO), chemical oxygen demand (COD), alkalinity, cations (Ca®", Mg", Na’, K‘, Zn”*, Cu", Mn” and Fe”), anions (CO;*, HCO;, NH3, NO.”, NO;,, $O,7, total nitrogen, total phosphorus and CI) and TDS (Total Dissolved Solids). Several variables such as SAR (Sodium Adsorption Ratio), SSP (Soluble Sodium Percentage) RSC (Residual Sodium Carbonate) and hardness were also computed. Overall we found that the pond water were acidic in nature (pH varied from 5.3 to 7.1) and could be suitable for agricultural and aquatic uses. Pond water samples contained Ca”, Mg” and Na’ as the dominant cations and HCO; and CI were the dominant anions. According to TDS and SAR values, all samples were classed as “freshwater and ‘excellent’ categories. The soluble sodium percentage (SSP) of all waters was under ‘excellent’ and ‘good’ classes. All samples were within ‘soft’ class regarding hardness with ‘suitable’ RSC. Based on Zn", Mn”, Fe”, $O,7, NO; and CI all pond water samples were within the ‘safe’ limit for irrigation used in dry period. The DO concentration was suitable for fish production but more DO level should be present for all aquatic life especially for fish production. COD level of all pond waters were within the permissible limits for fish production. However, water quality parameters of pH, temperature and DO are dominant factors to affect the growth of fish although BOD and COD parameters are not meeting the criteria. The studies were undertaken from the month of May to June, 2012 during which the physic-chemical parameters were analyzed and compared with the aquaculture water quality standard of Kumar (2004).