Study of the seasonal variations in Turag river water quality parameters

Abstract

The purpose of this study was to assess the degree of pollution of Turag river water by determining various physico-chemical parameters. Water samples were collected six times per year during wet and dry season at the following three locations: Tongi Railway Bridge, Bishwa Ijtema field and Ashulia. Most of the measured physicochemical parameters exceeded permissible limit of drinking water. The recorded pH ranged from 6.6 to 7.98 and Electrical Conductivity (EC) from 160 to 1107 µs/cm. The recorded dissolve oxygen (DO) varied from 0.11 to 6.8 mg/L and biological oxygen demand (BOD) ranged from 10 to 180 mg/L while chemical oxygen demand ranged from 21 to 220 mg/L and free CO2 value from 5 to 22 mg/L. The concentration ranges of heavy metals and arsenic in ppb were as follows: Zinc (Zn) (0.04 to 0.4), cadmium (Cd) (0.043 to 2), arsenic (As) (1.15 to 4.8), (lead) Pb (2.29 to 18.62) and mercury (Hg) (0.12 to 1.45). Due to the increased values of the parameters pH, DO, BOD, COD and free CO2 water from these locations was not suitable for human consumption without appropriate treatment.   Key words: Tongi railway bridge, Ijtema field, Ashulia, industrial effluent, aquatic ecosystem.