Water characteristics in Pattani bay

Water characteristics in Pattani Bay were investigated to evaluate the quality of water and environment status in Pattani Bay. Samples of water from the middle depth in Pattani Bay (8 stations), Pattani River (3 stations) and Yaring River (2 stations) were collected every 3-6 months from October 1991 to July 1994, and analysed for chemical, biological and physical parameters following the Standard Methods of APHA, AWWA and WEF (1992). It was found that the average values of depth at the stations where water samples were collected from Pattani Bay, Pattani River and Yaring River were 1.36+-0.17, 2.70+-0.31 and 4.55+-0.70 m, respectively. The values of average temperature from three sources were not significantly different, around 29 deg C. The average transparency values for Pattani Bay, Pattani River and Yaring River were 63.9+-12.1, 58.6+-8.4 and 100.6+-54.5 cm, respectively, while the values of the total suspended solids were 219.8+-103.2, 58.0+-55.8 and 90.4+-113.7 ppm respectively. The average salinity value of water in Pattani Bay was 25+-3 ppt, while those in two rivers could be measured at high tide. The marine water came further in Yaring River than in Pattani River. The average pH value of water in Pattani Bay (8.00+-0.17) was found to be higher than those in Pattani River (7.56+-0.21) and Yaring River (7.12+-0.36). The average phosphate-phosphorus content of water in Pattani Bay (10.6+-2.8 ppb) was found to be lower than those in Pattani River and Yaring River (33.0+-6.9 and 25.9+-11.0 ppb, respectively). Similarily, the average nitrite-nitrogen and nitrate-nitrogen quantities found in Pattani Bay (4.0+-2.4 and 49.8+-14.2 ppb) were lower than those in Pattani River (6.1+-2.1 and 173.0+-60.5 ppb) and in Yaring River (14.3+-11.9 and 119.3+-52.0 ppb). The average ammonium-nitrogen content in Pattani Bay was 61.3+-57.6 ppb which was lower than those in Pattani River and Yaring River (181.7+-112.1 and 195.2+-6.9 ppb, respectively). The average dissolved oxygen content in Pattani Bay was found to be equivalent to that in Pattani River (6.25+-0.63 ppm) but was higher than that in Yaring River (4.07+-1.06 ppm). Finally, the biochemical oxygen demand, BOD, values in Pattani Bay, Pattani River and Yaring River were 1.98+-0.42 and 2.63+-1.34 ppm respectively. From these analyses, it was concluded that Pattani Bay was less polluted than were Pattani River and Yaring River over 3-year period of investigation.