Groundwater Pollution Through Different Contaminants: Indian Scenario

The groundwater has emerged as major reliable source for agriculture as more than 60% of irrigated agriculture and 85% of drinking water supplies are dependent on groundwater. Round-the-clock water availability at the point of use, less conveyance losses, judicious water use and less cost of pumping are the major reasons behind the increased pumping of groundwater irrigation, but declining quality of groundwater has been becoming an issue of a concern, and it can be attributed to water contamination and/or over-exploitation. The contamination is taking place through various sources and pathways like anthropogenic (agricultural, industrial and domestic) and natural (geogenic/pedogenic origin) reasons. The basic cause behind drastic decline in groundwater quality is lack of appropriate rules and regulations, but off late to protect groundwater and take safeguards against over-exploitation, Government of India, in 1970, framed a Model Groundwater (Control and Regulation) Bill for adoption by the states and later on in the year 2013 started Atal Bhujal Yojana (ABHY) which focuses on interventions to improve groundwater quality. The main parameters that are considered to assess the contamination of groundwater by CGWB are salinity level; concentrations of fluoride, nitrate, arsenic and iron; and concentration of heavy metals like lead, chromium and cadmium, and the groundwater of most of the states of India like Punjab, Haryana, Uttar Pradesh, West Bengal, Tamil Nadu and Telangana was found to be contaminated by all these elements. Iron was found to be major contaminant in most of the states followed by fluoride, nitrate, arsenic, salinity and lead contamination. The indicators like pH, TDS, BOD and COD and metals like Cr, Cd, Ni, Zn, Cu, Pb, etc. are measured to know the extent of contamination. Sizable area in the vicinity of industrial sites is found contaminated by different kinds of contaminants that are elaborated in the text with level of concentration occurring in soil, plant as well as groundwater. The heavy metal pollution index was calculated to measure the overall quality of groundwater in the Ankleshwar Industrial Estate of Gujarat in India. Various techniques for remediating the contaminated groundwater are also discussed.