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Temporal assessment of the water quality along an urban estuary (Tagus estuary, Portugal)

dc.contributor.authorRodrigues, Marta
dc.contributor.authorCravo, Alexandra
dc.contributor.authorFreire, Paula
dc.contributor.authorRosa, Alexandra
dc.contributor.authorSantos, Daniela
dc.date.accessioned2021-06-24T11:35:29Z
dc.date.available2021-06-24T11:35:29Z
dc.date.issued2020-06
dc.description.abstractUnderstanding the natural dynamics of estuaries and their response to changes in the human-related or climatic drivers is fundamental to guarantee their environmental quality. This study aims to contribute to a better understanding of the water quality dynamics in an urban estuary, the Tagus estuary (Portugal), across different temporal scales. This estuary supports diverse uses and activities and its ecological value is well recognized. Three field campaigns were performed covering distinct seasons (Spring, Summer and Autumn - 2018). Physical, chemical and biological data were measured along the estuary. The acquired data was then integrated into a set of indicators and compared with historical data, to assess the long-term evolution of the water quality in the estuary. Results showed marked spatial gradients, typically with larger concentrations of chlorophyll a, nitrate and silicate upstream. Silicate and nitrate presented a conservative behavior. Ammonium and phosphate were not conservative, which suggests an anthropogenic pressure along the estuary. Seasonally, the highest nutrients and suspended solids concentrations were found in Autumn, after a period of rainfall, pointing out to the relevance of land runoff for material supply into the estuary. These conditions were favorable for phytoplankton development upstream, once chlorophyll a was maximum during this campaign (24 mu g/L in the upper estuary). Regarding the nutrients classification, results suggest that the upper estuary is at risk with a "Medium" status. The middle and downstream areas presented a "High" status, with the exception of the middle-right margin that is also at risk ("Medium" status). The assessment of the historical data suggests that high loads of nutrients have been reaching the Tagus estuary over time, with a decreasing trend in recent years. The trophic index (TRIX) suggests a "Moderate" trophic status in the middle and upstream areas of the estuary. As for nutrients, a "Poor" classification was obtained in the middle-right margin of the estuary, mainly due to ammonium concentrations, confirming an intensification of anthropogenic pressure at this site. Similarly to the nutrients status, TRIX suggests some improvement of the water quality in the Tagus estuary in recent years compared to the 1980s. These results provide further insight regarding the water quality dynamics in the Tagus estuary and are useful to support management.
dc.description.sponsorshipFCT - Fundacao para a Ciencia e TecnologiaPortuguese Foundation for Science and Technology [PTDC/AAG-MAA/6899/2014]
dc.description.versioninfo:eu-repo/semantics/publishedVersion
dc.identifier.doi10.1016/j.marchem.2020.103824
dc.identifier.issn0304-4203
dc.identifier.urihttp://hdl.handle.net/10400.1/16453
dc.language.isoeng
dc.peerreviewedyes
dc.publisherElsevier
dc.subjectNutrients
dc.subjectChlorophyll a
dc.subjectNutrients status classification
dc.subjectTRIX
dc.subject.otherChemistry; Oceanography
dc.titleTemporal assessment of the water quality along an urban estuary (Tagus estuary, Portugal)
dc.typejournal article
dspace.entity.typePublication
oaire.citation.startPage103824
oaire.citation.titleMarine Chemistry
oaire.citation.volume223
person.familyNameCravo
person.familyNameRosa
person.givenNameAlexandra
person.givenNameAlexandra
person.identifier.ciencia-id7419-EE20-8039
person.identifier.ciencia-id7B17-2CD2-0154
person.identifier.orcid0000-0002-2569-3929
person.identifier.orcid0000-0003-4443-9405
rcaap.rightsrestrictedAccess
rcaap.typearticle
relation.isAuthorOfPublicationf19c20c8-9654-43db-841b-2c6f14979df5
relation.isAuthorOfPublication3b77d30f-4085-462f-9d35-fc989bd4ad14
relation.isAuthorOfPublication.latestForDiscovery3b77d30f-4085-462f-9d35-fc989bd4ad14

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