Surface water quality deterioration due to industrial and agricultural processes is severe in Bangladesh, especially where the industrial and agricultural activities go side by side in and around the surface water systems. The present environmental research work has been carried out during pre-monsoon and post-monsoon period of 2009 to evaluate the environmental impacts of agro-industrial processes on the adjoining surface water systems in the southeastern outskirt of Dhaka City. Twenty composite water samples were collected from different water sources of the vast study area following standard sampling techniques. The major physical-chemical parameters were determined using advanced analytical techniques. The water quality parameters evaluated were Temperature,
Total Suspended Solids (TSS), Threshold Odour Number (TON), pH, Electrical Conductivity (EC), Dissolved Oxygen (DO), Biochemical Oxygen Demand (BOD), ChemicalOxygen Demand (COD), Total Dissolved Solids (TDS), Chloride, Bicarbonate, Phosphorus, Sulphur, Nitrogen, Calcium, Magnesium, Sodium, Potassium, Sodium Adsorption Ratio (SAR) and Heavy metals (Cu, Ni, Pb, Cd, Cr, Zn, Fe). Most of the parameters in both pre-monsoon and post-monsoon season were found above the maximum permissible limit. The values of all physico-chemical parameters were found to be higher in the pre-monsoon season than in the post-monsoon season except pH and DO. However, in both seasons the phosphorus, sulphur, potassium and Magnesium concentration of the study area were within the permissible limit for irrigation, industrial and recreational purposes. The sodium adsorption ratio values of the water samples were under low salinity and low sodium hazard and were suitable for irrigation except the areas of Dorikandi and Madanpur. The heavy metals concentrations were above the maximum allowable concentration in most of the areas irrespective of seasons. The quality of surface water systems of the study area was found to be unsuitable in both seasons for irrigation, industrial and recreational purposes. It is hoped that the findings of this research will be worthy and may be of value to future investigator in this fascinating field of sustainable environmental research.
The Earth is unique among the planets of the solar system for possessing large amounts of water on its surface. Water is the most abundant and important substance on the surface of the Earth (Deming, 2002). The organisms can live on biosphere of the Earth because it has an atmosphere. Seventy one percent of the earth surface is covered by water (Purohit and Ranjan, 2003; Sharma, 2003).
Water is essential for the survival of human and other organisms. Many ancient civilizations were located on the bank of rivers. These include the Tigris and Euphkates in Iraq, the Nile in Egypt, Indus in Pakistan and Ganges in India (Deming, 2002). Similarly, in Bangladesh most of the important cities like Dhaka, Narayanganj, Chittagong, Chandpur, Barisal and Khulna are located on the bank of rivers Buriganga, Laksha, Karnaphuli, Meghna, Kirtonkhola and Bhairab respectively (Anwar, 1993; Rahman et al., 2000).
The surface water systems of Bangladesh consist of the major networks, world largest delta and the massive flood plains, which become inundated in the monsoon season and supply most of the agricultural crops (Rahman et al., 2000; Islam and Shamsad, 2009; Islam et al., 2009; Karim, 2010). The socio-economic condition of the people is intimately linked with its two main sources: land and water. Water is its main boon and also the main causes or means of disaster. With population growth, there is an increasing pressure on land, water and energy to produce more goods for consumption. Modern agricultural and industrial technology can produce higher agricultural and industrial yields through increased and sufficient use of surface water (Cuena, 1989).
The history of human civilization reveals that water supply and civilizations are almost synonymous. Several cities and civilizations have disappeared due to water shortage (De, 1989; Goel, 2008; Deming, 2002). Water is an invaluable commodity available in the nature with limited quantities to man and other living being including flora and fauna. Quality is a term that is relative in its meaning and comparative in sense. The definition of water quality predicates on the intended use of the water and a gross determination of the quality of suspended and dissolved impurities (Peavy et al., 1985).
Water quality is influenced by natural and anthropogenic interventions where the former includes local climate, geology etc. and the later covers the construction of dams and embankments, agricultural practices, indiscriminate disposal of industrial effluents etc. (Pierzynski et al., 2000; Ryding and Rast, 1989). Understanding the sources, interactions, and effects of water pollutant is essential for controlling pollutants in an environmentally safe and economically acceptable manner (Pierzynski et al., 2000; Manahan, 2000).
According to Coulson and Forbes (1952), water pollution is defined as the “the addition of something to water which changes its natural qualities’’. De (1989), defined water pollution as a state of deviation from the pure condition where by its normal function and properties are affected. Water pollution is the alteration of any body of water by man or nature to such a degree that said body of water loses any of its value as natural resources (Sawyer et al., 2005). The vast amount of water may partially or locally be deteriorated by mixing pollutants. At present water pollution is the most serious environmental quality issue in the world (Nizam et al., 2009; Peavy et al., 1985; Davis and Cornwell, 1998).
The quality of water available to human has been vital factors in determining their well being. Water quality is often neglected although it is important in many areas including Bangladesh (Shamsad and Islam, 1999; Islam and Shamsad, 2009; Nizam et al., 2009; Shamsad et al., 2010). Surface water systems include rivers, streams, ponds, lakes, haors, baors, beels, reservoirs, tanks etc. that may be polluted in various ways. The main sources of surface water pollution are agricultural, industrial and domestic wastes, both solids and liquids (Dara, 2002; Islam and Shamsad, 2009; Shamsad et al., 1999; De, 1989). Industrial and domestic wastes and effluents are being randomly discharged without treatments onto natural water systems. The heavy metals, toxic substances, and in some cases, high amount of nitrate and ammonium nitrogen present in these wastes and effluents pollute surface water, ground water and soil. In this way, they create serious environmental hazards, endanger human health and cause problems to aquatic lives. Some of the pollutants are phytotoxic and some are toxic to both plant and animals through their entry into the water-soil-plant-food system (Peavy et al., 1985; Sawyer et al., 2005; Shamsad and Islam, 1999).
Water pollution due to toxic heavy metals has been a major cause of concern for environment (Peavy et al., 1985; Davis and Cornwell, 1998; Anwar, 1993). Huge amount of untreated industrial effluent and agricultural waste water are continuously being discharged into the surface water causing severe damage to the aquatic environment and adversely affecting ground water of the region by recharge. Heavy metals in water, even at trace level, are toxic and detrimental to agriculture, animal and human (Chhatwal et al., 1992; Mengal and Kirby, 1987; Shamsad and Islam, 1999). Exposure to heavy metal toxicity can result from every facet of national activity such as agriculture, mining, transport, energy and industry (Zimmy, 1984). Heavy metals like Cd, Pb, Cu, Ni, Zn, and Cr discharged by many vital industries like metal finishing, lather tanning, ceramics, pigments, paper, plastics and petrochemicals are more harmful to habitat (Helawell, 1986). These metals are involved in complex biogeochemical cycles and become the sediments of the floodplains and aquatic environment. Metals are available for uptake by a variety of aquatic organisms such as phytoplankton, accomplished by diffusion across the biological membrane. Fishes similarly transfer metals across membranes in their gills. Metals thus pass up the food chain and become a major source to human exposure (Krumbein and Sloss, 1963; Dara, 2002). Metal oxides accumulated in soils become chemically and biologically activated under the influence of an increasing acidity which changes the biological activity of the soil (Zimmy, 1984; Baran, 1976).
Water is essential to plant and animal life; it is our best solvent, it carries of our water, and it modifies our climate (Donahue et al., 1990; Deming, 2002). It is also a transporting agent for dissolved materials, nutrients, chemicals and solids (Hatfield and Karlen, 1994; Shamsad et al., 1999). For agricultural systems to be both productive and sustainable in the long term, management of water resource is required to ensure the sufficient water is available for plant growth and excess water is not allowed to contribute to land degradation (Hatfield and Karlen, 1994; Cuena, 1989).
In a locality, people use surface water for various purposes like domestic, industrial, recreational, aquaculture, agriculture etc. Lake and pond water in any community are used mainly for domestic supplies, recreation and aquaculture. The quality of lake and pond water is important for long term uses because it may affect community health and damage aquaculture practices and also create aesthetic problem in the locality (Goel, 2008; Islam et al., 2009). For example, an upstream chemical company that pollutes a river by discharging wastes into it, harms not only people downstream who drink river water but also fish in the river, birds who eat fish, and thousands of other organisms that live in or near the river. So every use of water requires a certain minimum quality of water with regards to the presence of dissolved and suspended materials of both chemical and biological nature. The minimum quality of water should ensure no harm to the user (De, 1989; Goel, 2008; Davis and Cornwell, 1998).
Ground water is in crisis although water as a renewable resource. Further, surface water quality decreases day by day due to political like Farrakha barrage and environmental problems like flood, drought, deforestation, salinization etc. (Rahman et al., 2000; Karim, 2010). Rapid urbanization is taking place; more lands are occupied for the industrial developments. Indiscriminate use of fertilizers, pesticides and other agrochemicals also degrade surface water quality especially where industry and agriculture go side by side (Islam et al., 2009; Shamsad and Islam, 1999; Manahan, 2000: Shamsad et al., 2010).
The present environmental research work is therefore undertaken to evaluate the water quality of surface water systems of vast areas of southeastern outskirt of Dhaka city, situated in Narayanganj district where agriculture and industry go side by side and to assess the possible environmental impacts of agro-industrial processes on the adjoining surface water systems.