Ensuring potable water security in BD
Arsenic poisoning of ground water in Bangladesh:
Arsenic concentration in natural water varies widely depending on the sources of water and local conditions. Arsenic concentration in rivers water is low, between 0.1 to 2.0 mg/l, but polluted river water can have higher concentration of As. High As concentrations are found in some alkaline closed-basin lakes due to high evaporation and geothermal inputs.
In Bangladesh and West Bengal, alluvial Ganges aquifers used for public water supply are polluted with naturally occurring arsenic, which adversely affects the health of millions of people. The arsenic derives from the reductive dissolution of arsenic-rich iron oxyhydroxides, which in turn are derived from weathering of base-metal sulphides.
As many as a million water wells drilled into Ganges alluvial deposits in Bangladesh and West Bengal may be contaminated with arsenic. Measured arsenic concentration reached up to 1,000 g/l, which is above limit set for drinking water in Bangladesh (50 g/l) or that recommended by the World Health Organization (10 g/l). Consumption of this contaminated water has led to widespread death and disease. Arsenic has been reported to derive from the oxidation of arsenic rich pyrite in the aquifer sediments as atmospheric oxygen invades the aquifer in response to a lowering of the water level by abstraction.
The arsenic rich groundwater is mostly restricted to the alluvial aquifers of the Ganges delta. The source of arsenic rich iron oxyhydroxides must therefore lie in the Ganges source region upstream of Bangladesh. Weathered base-metal deposits are known to occur. The Ganges basin, so weathering of these arsenic rich base metal sulphides must have supplied arsenic rich iron oxyhydroxides to downstream Ganges sediments during Late Pleistocene--Recent times. The arsenic-rich iron oxyhydroxides are now being reduced, causing the present problem. Reduction is driven by concentration of sedimentary organic matter of up to 6 per cent.
Action plan for the Bangladesh government:
The Government of Bangladesh, in its 'Action Plan for Poverty Reduction', has clearly stated that to ensure 100 per cent access to pure drinking water across the country. But the practical scenario is different where the people are affected by large amount of water impurities. 20 million people are suffering from Arsenicosis, keratosis, melanosis, and karato-melanosis (diseases of poor). That means 12.5 per cent of our total population. 43 thousand people are dying every year owing to consumption of impure water.
According to the water policy 1998, environmentally sound water management is suggested in utilization and development of water resources, construction of irrigation networks and embankments, dredging of water courses and in taking measures against river pollution. Environmental impact assessment is required before undertaking projects related to water resources development and flood control measures. The current scenario is not clearas people are deprived to access germ-free water. The 'right to flow' of rivers is affected. It meets the effective demand for criminalization of not only politics but also economics. Consequently, it is a truth-seeking deficiency of a state.
Constrains to afford pure potable water in Bangladesh:
The human rights challenge of provisioning of germ-free water in Bangladesh is a challenge from the viewpoints of both constitutional and justifiable rights. From that standpoint, heavy metal-free water for the citizens should view as public goods. But there are some financial, technical and social constraints. Govt. should overcome the financial constraints through effective water budget, providing incentives for raising water use efficiency, rights to water through abstraction charges, power sharing strategy among administrative actors, policy formation and implementation strategy etc.
It is important to resolve all technical constraints to accelerate the filtering process of heavy metals (nickel, lead, chromium, arsenic, cadmium) from impure water, emphasize surface water for irrigation and industry, engineering process of water supply and distribution, raising supply efficiency by having buried and plastic pipes in case of ground water, effluent treatment plant (liquid wastes, hard materials), sanitation, immunization and maternal health related issues. Similarly we have to address the social constraints (cropping pattern and diversification, patriarchy, climate, geographic variability, vulnerability and occupational structure) through communities 'knowledge attitude practice' towards life and livelihood.
In our country bottle water are also not safe to drink, studies mention. We have to initiate sustainable policy regarding water resources to provide pure water for all in Bangladesh.
The writer is an environmental analyst and associate member, Bangladesh Economic Association