The origin of high salinity and hydrogeochemical characteristics of groundwater in semi-arid area of the Linta Basin, Southwestern Madagascar

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00025798%3A_____%2F24%3A10169143" target="_blank" >RIV/00025798:_____/24:10169143 - isvavai.cz</a>

Alternative codes found

RIV/61989592:15310/24:73626921

Result on the web

<a href="https://doi.org/10.1016/j.jafrearsci.2024.105215" target="_blank" >https://doi.org/10.1016/j.jafrearsci.2024.105215</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.jafrearsci.2024.105215" target="_blank" >10.1016/j.jafrearsci.2024.105215</a>

Result language

angličtina

Original language name

The origin of high salinity and hydrogeochemical characteristics of groundwater in semi-arid area of the Linta Basin, Southwestern Madagascar

Original language description

The Linta Basin, located in the Southwestern Madagascar, is a semi-arid area where groundwater in fractured media bedrock aquifer constitutes the main source of water supply. In the last two decades, highly mineralized groundwater was identified in this area; however, the origin of the salinity was not clear. The purpose of the study was to clarify the origin of salinity and to identify hotspots with groundwater unsuitable for water supply. Groundwater quality in this basin was investigated by hydrogeochemical and isotopic methods accompanied by mineralogical study. In total, 32 groundwater samples were collected and analyzed. The results showed that groundwater temperature varied from 25.2 degrees C to 31.7 degrees C. Values of pH and TDS varied from 6.55 to 8.24 and 221 to 5612 mg/L, respectively. The aquifer, which is mainly fractured, showed 7 groundwater types, namely Mg-HCO3, Na-HCO3 and also Na-Cl, Mg-Cl, Na-Cl-HCO3, Mg-Cl-HCO3- , and Ca-Mg-HCO3. Two groups of variables have been identified by factor analysis; the factor F1 comprises EC, Ca2+, Mg2+, SO42- , and Cl- whereas the factor F2 comprises HCO3-, K+, and Na+, and they were interpreted in terms of hydrogeochemical processes. Values of saturation indices (SI) for carbonate minerals were generally positive, indicating their possible precipitation. Based on the Gibbs diagram and factor analysis, groundwater mineralization is affected by water-rock interactions and evaporation, respectively. The important role of evaporation is confirmed by enrichment of stable isotopes with delta O-18 values up to 1.2 parts per thousand. Processes such as base ionic exchange process and reverse ionic exchange process may also be important locally. The main origin of groundwater mineralization is the hydrolysis of silicate minerals such as feldspars and micas coupled with evaporation. In several wells, salinity is too high for water supply and nitrate concentration is above the WHO limit for drinking water. Results of the study highlighted groundwater chemistry formation processes and are applicable in other African countries with bedrock aquifers.

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

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OECD FORD branch

10505 - Geology

Project

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Continuities

V - Vyzkumna aktivita podporovana z jinych verejnych zdroju

Publication year

2024

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Journal of African Earth Sciences

ISSN

1464-343X

e-ISSN

1879-1956

Volume of the periodical

213

Issue of the periodical within the volume

105215

Country of publishing house

NL - THE KINGDOM OF THE NETHERLANDS

Number of pages

14

Pages from-to

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UT code for WoS article

001216294700001

EID of the result in the Scopus database

2-s2.0-85188007828