Water pollution, the release of substances into subsurface groundwater or into lakes, streams, rivers, estuaries, and oceans to the point where the substances interfere with beneficial use of the water or with the natural functioning of ecosystems. In addition to the release of substances, such as chemicals or microorganisms, water pollution may also include the release of energy, in the form of radioactivity or heat, into bodies of water. Water bodies can be polluted by a wide variety of substances, including pathogenic microorganisms, putrescible organic waste, plant nutrients, toxic chemicals, sediments, heat, oil, and radioactive substances.
Bangladesh is a riverine country. Bangladesh is renowned for its beautiful geomorphic features, including the massive rivers flowing throughout the country. Within the borders of Bangladesh lie the bottom reaches of the Himalayan Ranges’ water sources, which serve as the primary sources for rivers that flow through such countries as China, Bhutan, and India and eventually passing into the Bay of Bengal in Bangladesh. The Bangladesh Rivers also drive various economic activities such as agriculture, waterway communication, and energy source among others. Since these rivers play a significant role in the economic growth, it is therefore deemed important to study some of the major rivers like Padma, Meghna, Jamuna, Karnaphuli, Atrai River, Surma, Ganges, Brahmaputra in Bangladesh, focusing on the countries they flow through.
POLLUTION OF THE RIVER WATER:
The rivers of Bangladesh are the worse victim of pollution, especially the rivers which stands in the neighborhood of the Dhaka city is being polluted tremendously.
Causes:
1. Rapid and unplanned urbanization and industrialization, brickfield development, Dying factories, tanneries, Grabbing up the river.
2. The slum dwellers use unhygienic open latrines, wash clothes; take bath even cows and goats bathe in the river.
3. Untreated wastes are thrown into the river as most of the industries have no Effluent Treatment Plant.
According to an industrial survey conducted by Bangladesh Center for Advanced Studies (BCAS) in 2009, only about 40% industries have ETPs. In 10% industries, ETPs are under construction and about 50% industries have no ETP establishment. That is, more than 50% of waste generated by the industries eventually goes to the rivers untreated.
4. Some rivers are used to rot jute plants by the farmers.
5. Oil spills of boats and different water vessel.
6. Using agrochemicals in agricultural land.
Effects:
• Due to over spilling of pollutants during the rainy season, the agricultural lands are contaminated that they have lost their crop growing capacity and hence remain unused all the year round.
• Sometimes the pollutants enter food chain eventually killing birds, fish, and mammals.
• The scientists in a recent research on the Karnaphuli found traces of radioactivity ‘very close to risk level’ on the soil. If radioactivity of the river soil goes up it will hamper the natural breeding of fish as well as growth of fishes. If the people eat the affected fish it may spread to their body.
According to the United Nations Scientific Committee on the Effects of Atomic Radiation on 2000 (UNSCER), normal level of radiation hazard due to radioactivity is 0.5. The scientists in their research got 0.6507 for external radiation hazard and 0.82 for internal radiation hazard where the risk level is 1.
• Pollution is so acute that hardly any hydro-organisms can tolerate it and eventually, fish of many species are found floating dead in the river water. These dead fishes gradually get rotten and highly add to the further pollution of the river water
• Due to rotting jute in the river (Chitra) water the water quality of the river is in an inferior position as aquatic creatures are dying for lack of oxygen.
• The river pollution has also hit the local fishermen hard. Life has become difficult for them as they lost their income source.
• This also results in the alteration of geomorphic features which can then change in the geometry and sedimentary characteristics of river channels, flood plains and deltas.
• Industrial pollutants such as lead, cadmium, iron, copper and organic wastes from leaking sewage systems can accumulate in rivers. Referred as bioaccumulation, this process can ruthlessly affect water quality and species survival. More importantly, bioaccumulation of metals in fish, crabs and other edible aquatic species, may cause health problems to enter the food chain. Also, this can destroy the water aeration system, the self-purifying process of rivers.
• Eutrophication, a process of absorbing excessive nutrients (especially N and P) beyond their buffering capacity of water bodies leads to the loss of species diversity through increased species mortality, changes in species collection and loss of aquatic flora and fauna diversity.
Some steps to minimize pollution in last few years:
1. There is always a try to minimize pollution. Tongi Industrial Area have unanimously decided for establishing and operating a central ETP with their concerted effort with a view to tackling the Turag River pollution (Prothom-Alo, August 31, 2010). Some projects are initiated to lessen this huge pollution by the government though these all are not effective always.
2. The government has taken a decision to shift the tannery industry from Hazaribagh to Savar. The water board designed sluice gates on the Jamuna near the Bangabandhu Jamuna Bridge from where the waters would be diverted to the Buriganga.
3. The most striking reason of pollution river water is the surrounding industries like chemical industries, dying industries, tanneries etc. According to the Environment Conservation Act, 1995 (Amendment 2010), dyeing factories are “red category” industries and are bound to install and run an ETP.
Bangladesh is a natural laboratory and the place of highest species assemblage as well as species richness in the world, especially the southwestern coastal areas of the country. This area functions both as terrestrial and aquatic ecosystems ensemble. Alternative way should be thought to minimize the future impacts of climate change before reach at extreme level.
The Earth and it resources should be treated as a community rather than a commodity. Our river waterisn’t unlimited resources that can handle whatever we take out or dump in. These waters need protection.
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Habiba Sultana, Student
Department of Environmental Science & Disaster Management
Noakhali Science & Technology University