Water Quality of the World’s Largest Mangrove Forest

This study reports some physico-chemical parameters (BOD, COD, DO, TDS, TSS, EC, Eh, hardness, alkalinity, temperature, and content of Na + , Mg 2+ , K + , Ca 2+ , Cl - , SO4 2- , and HCO3 - of the Passur river in the Sundarbans, the world's largest mangrove forest. The study was conducted over four sampling points: Mongla, Dangmari, Koromjol, and Koromjol Creek of the Passur river during the year of 2008- 2009 at rainy, winter, and summer seasons. Overall, the water quality parameters of the river were acceptable during rainy season; however, moderate to high values of these parameters were appeared for winter and summer seasons. Result indicated that the concentration of TSS (10.8 -19.7 g/L) during summer and TDS (3.5-53.3 g/L) in all the season exceeds the recommended concentration for Bangladesh. The highest DO concentration (6.0-7.33 mg/L) was observed in winter; nonetheless, the highest BOD (20.2-28.0 mg/L) was obtained in summer season. Moreover, in summer, almost all sampling points showed high value of COD (19.0-38.0 mg/L). The alkalinity and hardness of river water was gradually increased in winter and summer seasons than that of the rainy season. Sea water intrusion and industrial discharge may contribute the high concentration of Cl - (12.5-4672 mg/L), SO4 2- (9.02-968.3 mg/L), HCO3 - (116-203.3 mg/L), Mg 2+ (4.86-583.2 mg/L), Na + (329-8839 mg/L) and K + (45.15-992.0 mg/L) ions. Throughout the year, for all sampling locations, the measured average temperature, pH, EC, salinity of Passur river water were well matched with studies performed in this area and other regions.