Assessing seawater intrusion in an arid coastal aquifer under high anthropogenic influence using major constituents, Sr and B isotopes in groundwater

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dc.creatorRogelio Ledesma Ruíz
dc.creatorJurgen Mahlknecht
dc.date2017
dc.date.accessioned2018-10-18T21:51:08Z
dc.date.available2018-10-18T21:51:08Z
dc.descriptionThe La Paz aquifer system (Baja California Sur, Mexico) is under severe anthropogenic pressure because of high groundwater abstraction for urban supply (city of La Paz, around 222,000 inhabitants) and irrigated agriculture (1900 ha). In consequence, seawater has infiltrated the aquifer, forcing the abandonment of wells with increased salinity. The objective of this study was to assess seawater intrusion, understand the hydrogeochemical processes involved and estimate the contribution of seawater in the wells tested. The aquifer comprises mainly the alluvial filling and marine sediments of a tectonic graben oriented north-south, in contact with the Gulf of California. Groundwater samples were collected in 47 locations and analyzed for major constituents. A subset of 23 samples was analyzed for strontium and boron concentrations and isotopic signatures (87Sr/86Sr and δ11B). Results were interpreted using standard hydrochemical plots along with ad hoc plots including isotopic data. Seawater intrusion was confirmed by several hydrogeochemical indicators, such as the high salinity in areas of intense pumping or the Na+-Ca2 + exchange occurring in sediments that were previously in chemical equilibrium with fresh water. However, seawater contribution was not sufficient to explain the observed concentrations and isotopic signatures of Sr and B. According to the isotopic data, desorption processes triggered by a modification in chemical equilibrium and an increase in ionic strength by seawater intrusion significantly increased Sr and probably B concentrations in groundwater. From a calculation of seawater contribution to the wells, it was estimated that one-third of the sampled abstraction wells were significantly affected by seawater intrusion, reaching concentrations that would limit their use for human supply or even irrigated agriculture. In addition, significant agricultural pollution (nitrates) was detected. Planned management of the aquifer and corrective measures are needed in order to invert the salinization process before it severely affects water resources in the long term. © 2017 The Authors
dc.identifier.doi10.1016/j.scitotenv.2017.02.137
dc.identifier.endpage295
dc.identifier.issn489697
dc.identifier.startpage282
dc.identifier.urihttp://hdl.handle.net/11285/630513
dc.identifier.volume587-588
dc.languageeng
dc.publisherElsevier B.V.
dc.relationhttps://www.scopus.com/inward/record.uri?eid=2-s2.0-85027954892&doi=10.1016%2fj.scitotenv.2017.02.137&partnerID=40&md5=d902683f56df9c0c9a1bb60fb44445f2
dc.relationInvestigadores
dc.relationEstudiantes
dc.rightsinfo:eu-repo/semantics/openAccess
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/4.0
dc.sourceScience of the Total Environment
dc.subjectAbandoned wells
dc.subjectAgriculture
dc.subjectAquifers
dc.subjectChemical modification
dc.subjectGroundwater
dc.subjectGroundwater geochemistry
dc.subjectGroundwater resources
dc.subjectIndicators (chemical)
dc.subjectIon exchange
dc.subjectIonic strength
dc.subjectIsotopes
dc.subjectMercury (metal)
dc.subjectPollution
dc.subjectSalt water intrusion
dc.subjectSeawater
dc.subjectStrontium
dc.subjectSubmarine geology
dc.subjectWater resources
dc.subjectAgricultural pollution
dc.subjectAnthropogenic influence
dc.subjectAnthropogenic pressures
dc.subjectCationic exchange
dc.subjectGroundwater abstraction
dc.subjectHydrogeochemical process
dc.subjectOverexploitation
dc.subjectSalinization
dc.subjectHydrochemistry
dc.subjectboron
dc.subjectcalcium ion
dc.subjectground water
dc.subjectisotope
dc.subjectnitrate
dc.subjectsea water
dc.subjectsodium ion
dc.subjectstrontium
dc.subjectstrontium 86
dc.subjectstrontium 87
dc.subjectunclassified drug
dc.subjectboron isotope
dc.subjectcoastal aquifer
dc.subjectexploitation
dc.subjectgroundwater abstraction
dc.subjecthuman activity
dc.subjection exchange
dc.subjectsaline intrusion
dc.subjectsalinization
dc.subjectstrontium isotope
dc.subjectwater chemistry
dc.subjectaquifer
dc.subjectArticle
dc.subjectcation exchange
dc.subjectconcentration (parameters)
dc.subjectcontrolled study
dc.subjectdesorption
dc.subjectionic strength
dc.subjectsalinity
dc.subjectsea pollution
dc.subjectsea water intrusion
dc.subjectBaja California Sur
dc.subjectGulf of California
dc.subjectMexico [North America]
dc.subjectPacific Ocean
dc.subject.classification7 INGENIERÍA Y TECNOLOGÍA
dc.titleAssessing seawater intrusion in an arid coastal aquifer under high anthropogenic influence using major constituents, Sr and B isotopes in groundwater
dc.typeArtículo
refterms.dateFOA2018-10-18T21:51:08Z

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