Groundwater arsenic in Chandrapur District, Central India

Abstract

To ascertain the groundwater arsenic concentration from the Chandrapur district of Maharashtra State of Central India grab water sampling was carried out in post-monsoon season from 36 sampling locations comprised of 34 from hand pump and two from dug well. Groundwater samples were analysed for general parameters by adopting standard methods as described in APHA (2017). Furthermore, groundwater arsenic concentration was estimated by using the acid digestion method and by using ICP-OES. The results revealed groundwater arsenic concentration presence in all the sampling locations. The groundwater arsenic concentration was in the range of 0.015-0.041 mg/L with an average concentration of 0.031 mg/L. All the samples had groundwater arsenic concentrations above the acceptable limit of the Indian Standard for arsenic (< 0.01 mg/L), although they were within the permissible limit (< 0.05 mg/L). Maximum (n = 23, 63.88%) groundwater samples had arsenic concentration between 0.03-0.05 mg/L followed by 13 (36.11%) in 0.01-0.03 mg/L. The groundwater arsenic concentration in different aquifers revealed the hand pump sample had a maximum arsenic concentration (0.041 mg/L). Pearson’s Correlation Coefficient indicated groundwater arsenic is positively correlated with chloride (0.13) and iron (0.16) and negatively correlated with fluoride (-0.21) and pH (-0.19). The groundwater arsenic concentration, electrical conductivity, and pH relationship revealed maximum groundwater arsenic concentration at <1000 mmhos/cm and >1000 mmhos/cm conductivity is obtained in acidic pH; whereas, minimum in near neutral and alkaline pH. The behaviour of groundwater arsenic below ground level revealed the maximum average concentration of 0.0339 mg/L at 35 feet below ground level (bgl) followed by 0.0328 mg/L at 300 feet bgl and minimum (0.0299 mg/L) at 190 feet bgl. Deep wells (101-150 feet bgl) had maximum average groundwater arsenic concentration (0.0326 mg/L) followed by shallow wells (<100 feet bgl) 0.0319 mg/L. From the results, it can be concluded that the presence of arsenic in the groundwater of study area and its origin can be geogenic in nature. The groundwater arsenic concentration was above the permissible limit and thus may pose a health risk to inhabitants who are drinking groundwater. A long-term study from the study area will shed light on spatio-temporal behaviour of groundwater arsenic. A local policy from the government is required to mitigate adverse impacts on the inhabitants. An alternative source of potable water should be made available to the inhabitants thus reducing chronic daily intake and hazards associated with it. A low-cost, environmentally friendly, easy-to-adopt, and understandable arsenic removal methodology will be a boon to the local people.