Groundwater salinization in the Azores archipelago (Portugal)

Groundwater salinization in coastal regions causes severe constraints to water supply and economic losses to society worldwide. In the Azores archipelago, groundwater abstraction in wells drilled in coastal aquifers is very important for water supply, and quality problems have been reported. Therefo...

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Bibliographic Details
Published in:Environmental earth sciences 2011-03, Vol.62 (6), p.1273-1285
Main Authors: Cruz, J. Virgílio, Coutinho, Rui, Pacheco, Dina, Cymbron, Raquel, Antunes, Paulo, Freire, Pedro, Mendes, Sandra
Format: Article
Language:English
Subjects:
Aquifers
Archipelagoes
Biogeosciences
Chemical analysis
Coastal aquifers
Coastal zone
Earth and Environmental Science
Earth Sciences
Earth, ocean, space
Environmental science
Environmental Science and Engineering
Exact sciences and technology
Geochemistry
Geology
Groundwater
Groundwater data
Hydrology. Hydrogeology
Hydrology/Water Resources
Mineralization
Mineralogy
Original Article
Saline water intrusion
Salinity
Salinization
Seawater
Silicates
Terrestrial Pollution
Water analysis
Water geochemistry
Water quality
Water resources
Water supply
Water wells
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Summary:Groundwater salinization in coastal regions causes severe constraints to water supply and economic losses to society worldwide. In the Azores archipelago, groundwater abstraction in wells drilled in coastal aquifers is very important for water supply, and quality problems have been reported. Therefore, a groundwater chemistry dataset from wells was compiled to study groundwater salinization in these aquifers. Waters are mainly of the Na–Cl type, presenting a slightly acidic to slightly alkaline character, with a pH between 5.63 and 8.50 (median 7.40). Electrical conductivity measurements range from 127 to 9,670 μS/cm (median 862), suggesting highly variable mineralization, with higher values observed on Santa Maria, São Miguel, Pico, Graciosa, and São Jorge islands. The major-ion composition reflects the contribution of seawater to the groundwater compositional evolution, which is essentially explained by seawater intrusion into wells. In many samples, exchange reactions of Na +  + K + for Ca 2+  + Mg 2+ are associated with salinization. The seawater fraction in groundwater composition reaches a maximum of 22.5%. These results are extremely challenging to water managers in the Azores because failure to comply with national water quality regulations and with European Union groundwater directive requirements often occurs.
ISSN:1866-6280
1866-6299
DOI:10.1007/s12665-010-0615-2