DOI: 10.11648/j.ajpc.20261503.12 ISSN: 2327-2449

Alteration of Mineral Balances in Groundwater and Surface Waters of Mangalmé: Correlation Matrix and Heterogeneous Critical Anomaliese

Hassan Mahamat, Haroun Adannou, Yaya Yaya, Balkis Adam, Ahmed Mohagir, Mohammedain Belal
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This study focuses on a semi-arid area of Chad—the Mangalmé department—where access to drinking water remains a major concern. The population relies primarily on groundwater (wells) and surface water (ponds/reservoirs) for drinking and domestic use. These resources are affected by climate change, notably through declining water table levels, the disappearance of water bodies, drought, and the degradation of vegetation cover. Compounding these issues are anthropogenic pressures linked to agriculture, livestock farming, and sanitation. The aim of this study is to assess the physicochemical quality of these waters, identify critical anomalies, and determine the sources of contamination in order to provide data useful for health and environmental management. To this end, ten (10) localities were monitored over a three-month period (March, April, and May). Water samples from wells and ponds were collected, georeferenced using GPS, stored in cool boxes, and analyzed in the laboratory. In situ measurements included pH at 25°C, electrical conductivity, total dissolved solids, and turbidity. Chemical analyses covered total hardness (CaCO 3 ), calcium (Ca 2 + ), magnesium (Mg 2 + ), potassium (K + ), sodium (Na + ), bicarbonates (HCO 3 − ), chlorides (Cl − ), sulfates (SO 4 2 − ), nitrates (NO 3 − ), fluorides (F − ), iron (Fe), and ammonium (NH 4 + ). The methods employed included volumetry, flame photometry, and HACH 2800 spectrophotometry. A correlation matrix and a normalized multiparameter comparison were used to interpret the relationships between parameters. The results reveal heterogeneous mineralization. Some water sources exhibit high conductivity and dissolved solids, very high turbidity, iron and fluoride concentrations exceeding WHO guidelines, and alarming ammonium levels. pH values vary, reflecting distinct geological and anthropogenic conditions. The correlation matrix reveals a strong interdependence among conductivity, dissolved solids, calcium, magnesium, chlorides, and sulfates, suggesting a common origin or similar chemical interactions. In conclusion, none of the ten sources analyzed fully meet potability criteria without treatment. The contamination is twofold: natural—linked to the weathering of sedimentary rocks (sandstone, carbonates, fluorite) that release fluoride and iron—and anthropogenic, involving ammonium from domestic, agricultural, and livestock waste. These findings necessitate regular monitoring, appropriate treatment, and measures to protect water resources.

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