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Comparison of the distribution of groundwater remediation units and contaminant (arsenic, iron, fluoride) distribution in Bihar, India for improved water security and management.
Abstract
Highlights
- Government installed groundwater remediation units (for As, Fe, F–) in Bihar mapped.
- Inconsistencies between remediation unit coverage and contaminant distribution.
- Extensive areas requiring remediation intervention may be not covered.
- Systematic and representative sampling recommended to support decision making.
- Transparency in decision-making criteria and administrative processes recommended.
Extensive efforts are being made globally to install units to remediate contaminants in groundwaters used for drinking, but are these units being installed in the optimum locations? Here, we explore this question for Bihar, an eastern Indian state with a high reliance on groundwater for drinking water. Bihar is impacted by groundwater quality issues, notably in relation to the geogenic contaminants arsenic (As), iron (Fe) and fluoride (F–). We map the distribution of groundwater quality remediation units for As, Fe and F–, and which were implemented from 2016 by the Government of Bihar under the aegis of the Public Health Engineering Department (PHED). The majority of the reported remediation units for As are within a distance of 10 km from the main branch of the River Ganges (Ganga), whereas the remediation units for Fe are exclusively present in the eastern and north-eastern districts of Bihar. All of the remediation units for F– are located in districts south of the River Ganges. The distributions of the installed remediation units are compared with the distribution and concentration of the target contaminants based on a representative Bihar-wide groundwater sampling campaign reported previously by our group. Inconsistencies are identified in many cases between the distribution of implemented remediation units and areas where elevated levels of the contaminant have been found. Some possible reasons for the apparent mismatches are discussed and include: prioritizing installation on the basis of now out-of-date contaminant distribution maps based on strongly non-representative sampling strategies, and administrative and operational convenience. Our study highlights that there are likely extensive areas in Bihar with groundwater quality issues where necessary interventions are required, but not yet received, whilst there seems to be widespread installation of remediation units where the need is less indicated. Several recommendations are made, including the need for representative, broad-scale (e.g. state-wide) testing to underpin robust decision making for optimal site selection for remediation unit installation for improved drinking water.
Graphical abstract
EXCERPTS:
Groundwater in Bihar, particularly south of the River Ganges, has also been reported to be affected by elevated F– concentrations, in excess of the WHO drinking water guideline value (1.5 mg/L) (WHO, 2017) in the districts of Gaya (Ahmad and Singh, 2023; Mridha et al., 2021; Yasmin et al., 2013), Nawada (Mridha et al., 2021), Munger (Kumari and Misra, 2023a), Jamui (Kumar et al., 2018b; Neeti and Singh, 2023) and Sheikhpura (Kumar et al., 2022). Symptoms of dental and skeletal fluorosis have been reported in these areas (S. Kumar et al., 2019; Kumari and Misra, 2023a): these symptoms can arise from chronic exposure to elevated levels of F– through drinking water (Ayoob and Gupta, 2006; Srivastava and Flora, 2020; Veneri et al., 2023; Zhou et al., 2023). The source of F– in contaminated regions of Bihar is thought to be geogenic, being particularly associated with granite gneiss hydrogeological settings (Kumar et al., 2018b).
Multiple agencies operate in India at the central (e.g. Central Ground Water Board (CGWB), Central Pollution Control Board) and state level (e.g. State Pollution Control Boards, Public Health Engineering Departments) and identify regions affected by selected groundwater contaminants. Lists made by such agencies are vital in water resource management and informing relevant stakeholders about groundwater quality status in a particular region. For example, the CGWB maintains a network of >14,000 groundwater monitoring stations throughout India (CGWB, 2020). Based on monitoring data, a list of districts affected with select groundwater contaminants (salinity, fluoride, nitrate, arsenic, iron, lead, cadmium and chromium, and more recently uranium (CGWB, 2020)) has been published (CGWB, 2019).
At the state-level, the Bihar Public Health Engineering Department (PHED) is tasked with identification of areas of groundwater contamination, which have been reported for As, Fe and F– (Bihar PHED, 2018a,b,c). Previously, the Bihar PHED has made substantial efforts to understand groundwater quality in Bihar via extensive groundwater testing and mapping locations where the contaminant concentration was found to be above guideline values (Bihar PHED, 2018a,b,c; Nickson et al., 2007). The government has installed remediation and mitigation units aimed to provide safer public drinking water in areas identified as contaminated (Bihar PHED, 2018a,b,c; Kumar et al., 2023b; Ranjan and Yasmin, 2019; Srikanth, 2013), as part of a wider mission to provide potable and piped drinking water supplies to households (Bihar Vikas Mission, 2023). Such units are installed, and maintenance overseen, by the Bihar PHED. Such an initiative ideally enables centralised monitoring and maintenance of installed systems and saves time for the residents in collecting water from the installed remediation units. Other states in India follow a similar system (Basak et al., 2021; Das et al., 2024; Ministry of Jal Shakti, 2021).
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FULL-TEXT STUDY ONLINE AT
https://www.sciencedirect.com/science/article/pii/S0301479724031438?via%3Dihub
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