Use of 223Ra and 224Ra as chronometers to estimate the residence time of Amazon waters on the Brazilian continental shelf

dc.creatorLEON, MORGANE
dc.creatorBEEK, PIETER van
dc.creatorSCHOLTEN, JAN
dc.creatorMOORE, WILLARD S.
dc.creatorSOUHAUT, MARC
dc.creatorOLIVEIRA, JOSELENE de
dc.creatorJEANDEL, CATHERINE
dc.creatorSEYLER, PATRICK
dc.creatorJOUANNO, JULIEN
dc.date2022
dc.date2022-08-09T18:27:56Z
dc.date2022-08-09T18:27:56Z
dc.date.accessioned2023-09-28T14:22:51Z
dc.date.available2023-09-28T14:22:51Z
dc.identifier0024-3590
dc.identifierhttp://repositorio.ipen.br/handle/123456789/33192
dc.identifier4
dc.identifier67
dc.identifier10.1002/lno.12010
dc.identifier90.5
dc.identifier94
dc.identifier.urihttps://repositorioslatinoamericanos.uchile.cl/handle/2250/9003411
dc.descriptionWhen rivers mix into the ocean, radium isotopes are released into the dissolved phase allowing us to apply these isotopes as powerful tracers of river plumes spreading into the ocean. We report 223Ra and 224Ra radium activities that were determined in the Amazon River mouth and along the Amazon plume that extends off the coasts of Brazil and French Guyana into the Atlantic Ocean. We summarize 223Ra and 224Ra data from AmasSeds (1991), AMANDES (GEOTRACES process study GApr01; 2007???2008) and M147 (2018) projects, which were conducted in different seasons corresponding to different Amazon discharge rates. We determined the 224Raex/223Ra activity ratios (AR) along the Amazon plume to derive apparent ages and to estimate the residence time of the Amazon waters on the Brazilian continental shelf. Our data suggest that it takes 9???14???d for the Amazon waters to reach the northern continental shelf off French Guyana and 12???21???d to reach the eastern part of the Brazilian continental shelf. These time scales are in good agreement with those derived from a high-resolution numerical simulation of the regional ocean dynamics. We do not find any relationship between the discharge rate of the Amazon River and the residence time of the waters on the Brazilian continental shelf, suggesting that the residence time of the Amazon waters is primarily driven by the ambient northwestward current. Using the apparent ages along the plume, we estimate an average velocity of 26???cm???s???1 for the northward transport of the Amazon waters on the continental shelf.
dc.format753-767
dc.relationLimnology and Oceanography
dc.rightsopenAccess
dc.subjectradium 223
dc.subjectradium 224
dc.subjectrivers
dc.subjectplumes
dc.subjectwater pollution
dc.subjectisotopes
dc.subjectamazon river
dc.titleUse of 223Ra and 224Ra as chronometers to estimate the residence time of Amazon waters on the Brazilian continental shelf
dc.typeArtigo de peri??dico
dc.coverageI


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