Int. j. econ. env. geol. Vol:2(2) 22-24, 2011
Introduction
The Ganges river is a major trans-boundary river which originated in the glacier of the Himalaya. The Ganges river runs a long distance on the Indo-Gangetic plain in India and enters Bangladesh at Shibganj of Chapai Nababganj district. Finally, it plunges into the Bay of Bengal. Rajshahi is one of the major cities in northwest Bangladesh, which is situated on the north bank of the Ganges river. The study area lies at the northwestern part of Bangladesh on the bank of the river Ganges. Several hydrological and geological studies have been conducted (Bhattacharya, et al., 1997; Acharyya et al., 2000; Rahman, 2004; Rasul and Jahan, 2010), which reveal that
22
Investigation of Water Quality in the Ganges River, Bangladesh:
Implications for Drinking and Household Purposes
MD. MINHAJ UDDIN MONIR
1*, YOUNUS AHMED KHAN
2, H. M. ZAKIR HOSSAIN
1AND
QUAZI HASNA HOSSAIN
31
Department of Petroleum and Mining Engineering, Jessore Science and Technology University of
Bangladesh (minhaj_04@yahoo.com)
2
Department of Geology and Mining, University of Rajshahi, Bangladesh
3
Department of Geoscience, Shimane University, 1060 Nishikawatsu, Matsue 690- 8504, Japan.
groundwater of the Rajshahi city and its surrounding areas is mostly contaminated with arsenic. Present water supply system of Rajshahi city area cannot meet the daily requirements of its residents. However, Ganges river can meet this water deficiency for the people living in Rajshahi city and on the bank of the Ganges river (Fig.1). The groundwater table of Rajshahi is declining by about 0.2-0.4 meter per year on an average (RDA, 2003). At present, groundwater is the only source of water in the Rajshahi city. The total demand of water is about 156,000 m3
/day and it meets the requirement of about 125,000 m3
/day (FCEAL, 2005). Rest of the water comes from other sources like ponds and river. Generally river water contains some impurities and by using this water, people suffer
Fig. 1. Location map of the study area.
from various diseases due to unsafe drinking water supplies (Ahmed and Rahman, 2000).
Water samples were collected in two-polypropylene and one-glass bottles from the Ganges river during pre- and post-monsoon periods during the year 2003 - 2004. Before sample collection, polypropylene and glass bottles were washed with dilute acid and rinsed by distilled water. Standard methods for chemical analysis were used following the procedure of Greenberg et al., (1995). Turbidity was measured by using the Jackson candle turbidimeter calibrated by suspensions of kaolin.
Water quality analyses were made on the basis of physical parameters and ionic concentrations. The water quality data during pre- and post-monsoon periods of the Ganges river are shown in Table 1. In pre- and post monsoon periods, mean value of pH of the Ganges river water is comparable (~8.5), to mean value of groundwater, DPHE (2004) and WHO (1993). In the pre-monsoon period concentration of Na and K is low in the river water, which is probably derived from weathering of feldspars in the source region. Progressive weathering due to heavy rainfall subsequently enriched Na ions within the river water (Hossain et al., 2010). The standard value of Na and K ions in the BDWS is 200mg/l and 12mg/l respectively (Rasul and Jahan, 2010). The mean value of Fe, Mn and Zn is lower than that of standard limits (Table1). The ionic contents of Cl
, HCO3 and SO4are
variable. Although, pH and the concentration of Na, K, Fe, Cl
-, HCO3- and SO4- increases after mixing with RCC
industrial drain as well as urban waste during pre-monsoon period, but the concentrations of Ca, Mg, Mn and Zn are invariable. Singh (1991) reported that pollutants are included into the river water from natural and anthropogenic sources. New natural source of water pollutants in the study area include soil erosion from northwestern Himalayan syntaxis, decomposition of plants and animals in or around the bank of the Ganges river. The enormous soil erosion raises the sediment load as well as turbidity of the Ganges river water. Similarly, the anthropogenic sources of water pollution are largely incorporated from industrial, agricultural and urban sources. Turbidity value of the Ganges river water is lower in the pre-monsoon period (~35 to 70 JTU), whereas in post-monsoon period turbidity values are highly enriched (up to 270 JTU) due to advanced weathering produced by humid monsoon climate. The standard turbidity values of DPHE (2004) and WHO (1983,1993) are 10 JTU and 5 JTU respectively. Thus, high turbidity values during post-monsoon are mostly related to the influx of clay materials within the river water. The suspended sediments are washed out through the river water and coarse material subsequently settled down at the bottom of the river, which, in turn increases turbidity during the monsoon period.
The Ganges river water parameters are comparable with drinking water standard (DPHE, 2004; WHO, 1993 and 1983) and ground water values of RCC, 2003, indicating that all physicochemical parameters are within safe limit except the turbidity. It is thus concluded that after
Table 1. Chemistry of the Ganges river water in comparison to other standards.
controlling the turbidity in the Ganges river water, it can be safely used for drinking and domestic purposes.
Acknowledgement
Authors thank Md. Parvez Mamud, Assistant Engineer, Water Supply Section, RCC and Md. Afzal Hussain, Project Director, DPHE, Rajshahi for providing logistical support.
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