{"title":"Assessing groundwater quality and solute sources in highly anthropized areas. The case of Abuja Federal Capital Territory, Nigeria","authors":"M. Etuk , V. Re , S. Viaroli , B. Raco , O. Igwe","doi":"10.1016/j.gsd.2025.101425","DOIUrl":null,"url":null,"abstract":"<div><div>The Abuja Federal Capital Territory is an example of a heavily anthropized aquifer, where natural water-rock interaction processes are masked by human pollution. As a result, the characterization of natural processes is particularly difficult, especially to disentangle the natural from the anthropogenic signature. Two surveys were conducted in the rainy and dry season in 2021 and 2022 using an integrated geochemical, statistical, and isotopic approach. Results show that groundwater samples are affected by mixing processes between water with a Ca-HCO<sub>3</sub> facies (associated to natural water-rock interaction processes) and contaminated waters. The latter can be observed in some wells with a shift to NO<sub>3</sub>-dominant facies in the rainy season. The stable isotopes of the water molecule (δ<sup>18</sup>O and δ<sup>2</sup>H) suggest the presence of multiple recharge zones and strong seasonal variability. The shifts in groundwater isotopic composition suggest secondary evaporation in the rainy season and limited local precipitation influence during the dry season, with a possible domination of deep aquifer contributions.</div><div>The frequency distribution of tritium (<sup>3</sup>H) in 2021 confirms the limited impact of local precipitation during the dry season (median 0.8 <span>TU</span>), further supporting the dominance of deep aquifer contributions to groundwater flow. The influence of rainwater infiltration is observed as a main contribution to the remobilization of contaminants (of agricultural and domestic origin) stocked in the unsaturated zone, rather than a dilution effect. This results in a progressive increase of NO<sub>3</sub><sup>−</sup> concentration in the rainy season (reaching 433 mg/L), highlighting the need for a more complete characterization to support a wiser sustainable environmental management in an area subject to increasing anthropogenic pressure and prone to significant population growth.</div></div>","PeriodicalId":37879,"journal":{"name":"Groundwater for Sustainable Development","volume":"29 ","pages":"Article 101425"},"PeriodicalIF":4.9000,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Groundwater for Sustainable Development","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2352801X25000220","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ENGINEERING, ENVIRONMENTAL","Score":null,"Total":0}
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Abstract
The Abuja Federal Capital Territory is an example of a heavily anthropized aquifer, where natural water-rock interaction processes are masked by human pollution. As a result, the characterization of natural processes is particularly difficult, especially to disentangle the natural from the anthropogenic signature. Two surveys were conducted in the rainy and dry season in 2021 and 2022 using an integrated geochemical, statistical, and isotopic approach. Results show that groundwater samples are affected by mixing processes between water with a Ca-HCO3 facies (associated to natural water-rock interaction processes) and contaminated waters. The latter can be observed in some wells with a shift to NO3-dominant facies in the rainy season. The stable isotopes of the water molecule (δ18O and δ2H) suggest the presence of multiple recharge zones and strong seasonal variability. The shifts in groundwater isotopic composition suggest secondary evaporation in the rainy season and limited local precipitation influence during the dry season, with a possible domination of deep aquifer contributions.
The frequency distribution of tritium (3H) in 2021 confirms the limited impact of local precipitation during the dry season (median 0.8 TU), further supporting the dominance of deep aquifer contributions to groundwater flow. The influence of rainwater infiltration is observed as a main contribution to the remobilization of contaminants (of agricultural and domestic origin) stocked in the unsaturated zone, rather than a dilution effect. This results in a progressive increase of NO3− concentration in the rainy season (reaching 433 mg/L), highlighting the need for a more complete characterization to support a wiser sustainable environmental management in an area subject to increasing anthropogenic pressure and prone to significant population growth.
期刊介绍：
Groundwater for Sustainable Development is directed to different stakeholders and professionals, including government and non-governmental organizations, international funding agencies, universities, public water institutions, public health and other public/private sector professionals, and other relevant institutions. It is aimed at professionals, academics and students in the fields of disciplines such as: groundwater and its connection to surface hydrology and environment, soil sciences, engineering, ecology, microbiology, atmospheric sciences, analytical chemistry, hydro-engineering, water technology, environmental ethics, economics, public health, policy, as well as social sciences, legal disciplines, or any other area connected with water issues. The objectives of this journal are to facilitate: • The improvement of effective and sustainable management of water resources across the globe. • The improvement of human access to groundwater resources in adequate quantity and good quality. • The meeting of the increasing demand for drinking and irrigation water needed for food security to contribute to a social and economically sound human development. • The creation of a global inter- and multidisciplinary platform and forum to improve our understanding of groundwater resources and to advocate their effective and sustainable management and protection against contamination. • Interdisciplinary information exchange and to stimulate scientific research in the fields of groundwater related sciences and social and health sciences required to achieve the United Nations Millennium Development Goals for sustainable development.
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