Overview of Groundwater Arsenic Contamination in Nepal

Abstract

This paper provides a comprehensive overview of arsenic contamination in the groundwater of Nepal, with a particular focus on the southern Terai region. Nepal’s diverse geographical landscape ranges from the high peaks of the Himalayas in the north to the flat plains of the Terai in the south, encompassing various geological zones including the Tibetan Tethys, Higher Himalaya, Lesser Himalaya, Siwaliks, and the Terai Plain. The Terai region, characterized by its flat alluvial plains, is home to over half of the population and faces significant issues related to arsenic contamination in groundwater. Residents in the mountainous and hilly regions primarily rely on surface water and natural springs for drinking, unaffected by arsenic contamination. However, in the Terai region, the reliance on groundwater sources such as tube wells and hand-pumped wells, both shallow and deep, has led to widespread arsenic contamination. Studies reviewed in this paper indicate that arsenic levels in these groundwater sources frequently exceed the WHO (World Health Organization) safety standards, raising serious public health concerns. Research by Bhusal and Poudyal revealed that detectable levels of arsenic were found in tube wells ranging from approximately 30 to 70 feet deep, indicating that shallow aquifers contain harmful levels of arsenic. This is particularly concerning in rural areas, where untreated groundwater is commonly used for domestic purposes. Conversely, urban areas have largely mitigated this issue through municipal water supply systems that provide treated deep boring water, which is generally safe from arsenic contamination. This paper aims to evaluate and analyze the extent of arsenic contamination in groundwater, its effects on human health, and the disparity between rural and urban water safety. The paper underscores effective treatment solutions and policy interventions to reduce arsenic exposure by integrating data from various studies and reports.

Additionally, the paper offers recommendations for future research and practical measures to address and mitigate the health risks associated with arsenic in drinking water in Nepal.