Tracking the fate of arsenic in groundwater discharged to the Meghna River

Abstract: The fate of arsenic fluxes to rivers from shallow aquifers is influenced by hydraulic head differences, and the geochemistry and geometry of aquifers and aquitards adjacent to the river. In our study area the eastern side of the Meghna River is generally strongly gaining year-round with some exceptions. The distribution of solid-phase Fe, Mn and As in riverbank sediments was correlated to variations in hydraulic gradients and hydraulic conductivity. The 30 m deep shallow aquifer was mapped 500 m parallel and orthogonal to the river bank at 3 locations, on both sides of the river, using Electrical Resistivity Tomography (ERT). The aquifer dimensions and properties are remarkably consistent between sites. The continuity of the 3–4 m capping clay layer will prevent shallow groundwater from discharging along the shallow river banks. Substantial seasonal fluctuations in dissolved As and Fe concentrations within the aquifer are related to irrigation pumping and natural river level fluctuations.

Download paper here

Recommended citation: Knappett, P. S. K., Myers, K., Shuai, P., Rhodes, K., Jewell, K., Peterson, J., et al. (2016). Tracking the fate of arsenic in groundwater discharged to the Meghna River. In Arsenic Research and Global Sustainability - Proceedings of the 6th International Congress on Arsenic in the Environment, AS 2016. https://doi.org/10.1071/EN17104