Hydrochemistry of surface water and groundwater in the shale bedrock, Cross River Basin and Niger Delta Region, Nigeria

Abstract

Water chemistry in the shale bedrock of the Cretaceous-Tertiary of the Cross River and Niger Delta hydrological basins has been investigated using major ions. To carry out a characterization of the water bearing units, 30 and 16 representatives surface and groundwater samples were collected. The evolution of the water is characterized by enhanced content of sodium, calcium and sulphate as a result of leaching of shale rock. The spatial changes in groundwater quality of the area shows an anomalous concentrations of ions in the central parts, while lower values characterize the eastern part of the basin covering Ogoja, Ikom and Odukpani areas. The values of total dissolved solids (TDS) and ions increases down gradient in the direction of groundwater flow. The dissolution of halite and gypsum explains part of the contained Na ? , Ca 2? , Cl -and SO 4 2-, but other processes such as ion exchange, silicate weathering and pyrite oxidation also contribute to water composition. The assessment with contamination indicators such as TDS, hardness, chloride, nitrate and sulphate indicates that the water in area is suitable for human consumption in some locations. Modelling using MINTEQA2 program shows that the water from all the shale water bearing units are under saturated with respect to gypsum.

Conflicts – Oil Exploration and Water

“…The impact on freshwater resources of oil and oil related activities and chemicals are exemplified by the leakages in the Niger Delta. Oil contaminants have been detected in virtually all water media used by the public for different purposes, from surface water to rainwater and from hand‐dug wells to borehole groundwater sites . The social and economic consequences have been devastating for the local population and are further discussed in the next section.…”

“…Oil contaminants have been detected in virtually all water media used by the public for different purposes, from surface water to rainwater and from hand-dug wells to borehole groundwater sites. [15,23,[53][54][55][56] The social and economic consequences have been devastating for the local population and are further discussed in the next section.…”

Seasonal Hydrological Inputs of Major Ions and Trace Metal Composition in Streams Draining the Mineralized Lom Basin, East Cameroon: Basis for Environmental Studies

“…Sulphate loadings were low for both seasons. Sources of dissolved SO 4 2-in surface water include dissolution of SO 4 minerals, oxidation of pyrite and organic sulphides in natural soil processes, and sulphur-based fertilisers (Hem 1985;Grasby et al 1997;Kumar et al 2006;Nganje et al 2015). Since agricultural activities are practiced on a fairly small scale in this area, the use of sulphur-based fertilisers is not common.…”

“…Hydrogeochemical processes help to unravel changes in surface water quality relating to water-rock interaction or anthropogenic impacts (Singh et al 2005;Kumar et al 2006;Franz et al 2014;Nganje et al 2015;Kamtchueng et al 2016). The geochemical properties of surface water also depend on the chemistry of the recharging source as well as the various geochemical processes occurring within the drainage basin.…”

“…The latter is often responsible for seasonal variations in surface water chemistry (Eneji et al 2012); hence, the chemistry of streamwater flowing through a basin can evolve through interaction with weathering products and precipitation. In addition, dissolution and ion exchange reactions as well as anthropogenic actions including artisanal mining activities, which have the potential to damage the environment through water pollution, do play an important role in modifying the chemical composition of streamwater along flow paths (Hook 2005;Ako et al 2014;Agyarko et al 2014;Kpan et al 2014;Simbarashe and Reginald 2014;Nganje et al 2015;Rakotondrabe et al 2017).…”