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| Arsenic contamination in groundwater | |
|---|---|
| Name | Arsenic contamination in groundwater |
| Location | Worldwide |
| Discovered | Antiquity |
| Causes | Natural geogenic sources; anthropogenic activities |
Arsenic contamination in groundwater is the occurrence of elevated concentrations of arsenic in subsurface aquifers used for drinking, irrigation, and industrial purposes. This phenomenon affects millions across regions including South Asia, Southeast Asia, and parts of North America, Africa, and South America, and intersects with historical events, public health crises, and international responses led by organizations and national agencies. It has motivated research programs at universities and initiatives by agencies such as the World Health Organization and national ministries.
Natural processes in geological formations and human activities in mining, agriculture, and industry have produced widespread arsenic occurrences in aquifers underlying areas like the Bengal Delta, Mekong Delta, and parts of the Great Plains. Prominent locations linked to severe exposures include communities associated with the Ganges–Brahmaputra Delta, Bengal Basin, Indus Basin, Yangtze Basin, and the Liao River Basin, where groundwater wells installed during public health campaigns interacted with sedimentary geochemistry. Responses have involved collaborations among institutions such as the World Health Organization, United Nations Environment Programme, United States Environmental Protection Agency, and national research councils, as well as field programs by universities and non-governmental organizations.
Arsenic in groundwater originates from geogenic sources in arsenic-rich mineral assemblages, including arsenopyrite, realgar, and orpiment within sedimentary bedrock and alluvial deposits influenced by tectonic and sedimentary history like that of the Himalaya and Tibetan Plateau. Redox-driven mobilization, including reductive dissolution of iron oxyhydroxides during organic matter degradation, desorption under alkaline conditions, and competitive exchange with phosphate from agricultural fertilizers, controls arsenic speciation between arsenite and arsenate. Anthropogenic contributions arise from mining districts such as those tied to historical metallurgy in the Rocky Mountains, Potosí, and the Ural region, industrial effluents linked to chemical plants, and pesticide applications seen in agricultural landscapes influenced by the Green Revolution. Hydrogeological factors including aquifer stratigraphy, groundwater flow dynamics studied in contexts like the Nile Delta and Mississippi Alluvial Plain, and aquifer recharge patterns influenced by river systems such as the Brahmaputra and Mekong determine spatial variability.
Chronic exposure to inorganic arsenic compounds via drinking water is associated with dermatological manifestations, peripheral vascular disease, and several internal cancers; epidemiological evidence has emerged from longitudinal cohort studies in Bangladesh, West Bengal, Taiwan, and Chile. Toxicological pathways involve trivalent arsenite and pentavalent arsenate interfering with cellular respiration, DNA repair mechanisms, and signal transduction, as elucidated in laboratory research at institutions such as the National Institutes of Health and academic centers studying mechanisms relevant to Bowen’s disease, lung cancer clusters, and cardiovascular outcomes. Public health surveillance by ministries of health and agencies including the Centers for Disease Control and Prevention has documented dose–response relationships, and landmark investigations such as those led by researchers in Dhaka and Kolkata framed policy thresholds adopted by bodies like the World Health Organization and the European Union.
Detection employs field test kits, laboratory-based atomic absorption spectroscopy and inductively coupled plasma mass spectrometry performed by national laboratories, academic cores, and commercial services, complemented by geospatial mapping using tools developed at research centers like the British Geological Survey and US Geological Survey. Monitoring programs integrate well inventories, community surveys led by municipal agencies, and remote-sensing informed hydrological models used by intergovernmental projects to prioritize sampling in basins including the Bengal Delta and Mekong Delta. Citizen-science efforts coordinated with universities and non-governmental organizations have supplemented formal monitoring, while quality assurance and proficiency testing overseen by standards bodies ensure data comparability across jurisdictions such as the European Commission and national standards institutes.
Point-of-use and centralized treatment technologies include adsorption onto activated alumina and granular ferric hydroxide, coagulation-flocculation followed by filtration implemented in community plants, ion exchange resins deployed in municipal systems, and membrane technologies exemplified by reverse osmosis units used in pilot projects. Phytoremediation trials using arsenic-accumulating plants have been conducted in contaminated floodplains under programs administered by agricultural research institutes, while permeable reactive barriers and in situ bioremediation approaches leveraging sulfate-reducing bacteria have been explored in field demonstrations supported by environmental agencies. Waste management of arsenic-bearing residuals requires hazardous-waste protocols enforced by environmental protection authorities and linked to public health regulations.
Regulatory responses reflect science-policy interfaces where international guidelines by the World Health Organization and legal standards set by entities such as the European Union, United States Environmental Protection Agency, and national legislatures establish maximum contaminant limits. Policy instruments include well-labeling programs, safe water provision schemes run by ministries of water and sanitation, and rural development projects financed by multilateral banks and development agencies to install deep tube wells, arsenic-safe piped supplies, and rainwater-harvesting systems. Risk communication and stakeholder engagement draw on experiences from public inquiries, court cases, and community advocacy led by civil society groups and public interest litigations in national courts.
South Asia: Extensive research and mitigation initiatives in Bangladesh and West Bengal involved mass testing campaigns, installation of deep aquifer wells, and collaborations among institutions like the Bangladesh University of Engineering and Technology, Indian Council of Medical Research, and international donors. Southeast Asia: Mekong River Basin studies coordinated by regional bodies and universities documented seasonal variability and prompted pilot treatment adoption. North America: Legacy mining districts in states such as Arizona and Montana spurred interventions by the United States Environmental Protection Agency and state departments. South America and Africa: Case studies in Chile, Argentina, and parts of East Africa informed adaptive management strategies by national ministries and the Pan American Health Organization. These regional efforts continue to shape interdisciplinary research agendas at universities and research institutes and guide implementation by development banks and health ministries.
Category:Groundwater contamination