Arsenic in groundwater can have either geogenic or anthropogenic origins. The geogenic As
can also be distributed to a larger extent by human activities. Arsenic contaminated groundwater is seen as one of the most critical routes of human exposure to geogenic pollutants. Hydrogeochemical analytical data related to the As concentration is estimated at Gyantoli village in Begusarai district in Bihar state to identify the natural background level of As using Grubb’s test and cumulative probability plots. The natural background level is a crucial parameter for identifying and quantifying groundwater pollution and seperated the anthropogenic addition of As in groundwater by the estimated inflection point.
The dominance of carbonate weathering along with relatively high pH values (8.00-9.00) helps to release of As in groundwater. Chemical analysis suggests the low contribution of cations through silicate weathering in groundwater. Anthropogenically, improper usage of water for irrigation and fertilizer usage induced phosphate mobilisation from fertilizers below the shallow aquifers, resulting in As being mobilised. The reducing environment of the aquifer becomes oxic at shallower depth, and the impressive water level fluctuation observed resulting vertical mixing of anthropogenic As contaminant. It is also found that the maximum As concentration is 8-times higher than the acceptable limit of drinking water.
Rahman, A., Mondal, N.C., Fauzia, F., Arsenic enrichment and its natural
background in groundwater in the proximity of active floodplains of Ganga River, Northern India, Chemosphere, https://doi.org/10.1016/j.chemosphere.2020.129096 .