Threat of arsenic contamination, salinity and water pollution in agricultural practices of Sundarban Delta, India, and mitigation strategies

Abstract

The paper through a critical appraisal of the agricultural practices in the Indian Sundarban deltaic region explores the tripartite problems of arsenic biomagnification, salinity of arable lands and ingress of agrochemical pollutants into the freshwater resources, which endanger the health, livelihood and food security of the rural population inhabiting the delta. The threefold problem has rendered a severe blow to the agrarian economy consequently triggering large-scale outmigration of the rural population from the region. Although recent studies have addressed these issues separately, the inter-connectivity among these elements and their possible long-term impact upon sustainability in the Sundarbans are yet to be elucidated. In the current scenario, the study emphasizes that the depleting freshwater resources is at the heart of the threefold problems affecting the Sundarbans. Owing to the heavy siltation of the local river systems, freshwater resources from the local ravines have salinized beyond the point of being used for agricultural purposes. At the same time, increasing salinity levels resulting from fluctuation of pre- and post-monsoon rainfall, frequent cyclones and capillary movement of salinized groundwater (primarily during the Rabi season) have severely hampered the agricultural practices. Salinization of above groundwater reserves has forced the farmers toward utilization of groundwater, which are lifted using STWs, especially for rice and other cultivations in the Rabi season. The Holocene aquifers of the region retain toxic levels of arsenic which are lifted during the irrigation process and are deposited on to the agricultural fields, resulting in bioaccumulation of As in the food products resourced from the area. The compound effect of consuming arsenic-contaminated food and drinking water has resulted in severe health issues recorded among the local population in the delta. Furthermore, due to the sub-optimal conditions for sustaining agriculture under saline stress, farmers often opt for the cultivation of post-green revolution high-yielding varieties, which require additional inputs of nitrogen-based fertilizers, organophosphate herbicides and pesticides that are frequently washed away by runoff from the watershed into the low-lying catchment areas of the biosphere reserve. Such practices have endangered the vulnerable conditions of local flora and fauna. In the present situation, the study proposes mitigation strategies which necessitate the smart use of locally obtainable resources like water, adaptable cultivars and sustainable agronomic practices like organic farming. The study also suggests engaging of conventional plant breeding strategies such as “Evolutionary plant breeding” for obtaining cultivars adapted to the shifting ecological conditions of the delta in the long run.