Bangladesh is known as the land of the rivers. Dhaka city, the capital of Bangladesh is surrounded by the rivers-Turag, Buriganga, Dhaleshwari, Balu and Shitalakhya. A number of canals are connected to these rivers, which form a river canal network system. There are both residential and industrial units besides these rivers which are prime source of pollution of these rivers. The untreated waste water discharges by the industries cause serious pollution. Besides, non point sources along with the stretch of the river are also important sources of pollution of these rivers. (IWM, 2004)
The river Turag running by the side of the Dhaka city, the capital of Bangladesh, is one of the most polluted rivers in Bangladesh. Many industries have set up in and around the Dhaka city during the last decade, and the number of the new industries are continually increasing.
The water quality of Turag is deteriorating day by day. This is affecting the natural resources and is crucial for the survival for all living organisms including human, food production & economic development. Today there are many cities worldwide facing an acute shortage of water and nearly 40% of the world’s food supply is grown under irrigation& a wide variety of industrial process depends on water. The Dhaka water supply and sewage authority is entrusted with the supply of piped water in the Dhaka metropolitan and its adjacent area. The present water supply coverage is 75% out of which 82% is derived from the ground water sources using a network of 415 deep tube wells, the remaining 18% is derived from surface water bodies comprising the peripheral river around Dhaka city. (Ahmed & Rahman, 2000)
The pollution of the Turag River has become a major problem due to uncontrolled & untreated discharge of raw sewage, garbage & industrial wastes. The natural purification of polluted water in itself is never fast, while heavily polluted water may traverse long distance in days before a significant degree of purification is achieved. (Mc.Gauhey, 1968, Peavy, 1986). So the river is slowly turning into canal carrying polluted water.
The sediment of the Turag River is also increasingly being polluted with the cities thousands of industrial units and sewerage lines dumping huge volumes of toxic wastes which contain lots of heavy metal into it day and night. Heavy metals contamination in aquatic environment is of critical concern, due to toxicity of metals and their accumulation in accuatic habitats. Trace metals in contrast to most pollutant, not biodegradable and they undergo a global ecological cycle in which natural water are the main path ways. Of the chemical pollutants heavy metal being non- biodegradable, they can be concentrated along the food chain, producing their toxic effects at points after far removed from the sources of pollution. (Tilzer and Khondoker, 1993).exposure to heavy metals has linked to several human diseases such as development retardation or malformation, kidney damage, cancer, abortion, effect on intelligence and behavior, and even death in some cases of exposure to very high concentrations.
Exemplifying the riverine character of Dhaka, the Turag is abundant in fish but suffers from acute water pollution. While attempts have been made to marginally widen the river the majority of industry has made little effort to follow environmental law and the water has become visibly discolored.
The River Turag is getting drastically narrow near Istema Maidan in Tongi as land encroachers pile up sands indiscriminately on the river bank, gradually extending their greedy hands towards its bed. River encroacher back after two years of hibernation; rampant onslaught narrows the river down a canal. The Turag River in Dhaka, Bangladesh flowing along northern vicinity the capital is virtually disappearing from the map thanks to indiscriminate encroachment on the river for years. If the trend...