The influence of sediment sources on radium-derived estimates of Submarine Groundwater Discharge
Rodellas, Valentí (Universitat Autònoma de Barcelona. Institut de Ciència i Tecnologia Ambientals)
Garcia-Orellana, Jordi (Universitat Autònoma de Barcelona. Departament de Física)
Masqué Barri, Pere (Universitat Autònoma de Barcelona. Departament de Física)
Font-Muñoz, Joan S. (Institut Mediterrani d'Estudis Avançats)

Date:	2015
Abstract:	The influence of sediments on the determination of SGD by using Ra isotopes was investigated in the Port of Maó (Balearic Islands, NW Mediterranean). This natural harbor was selected because SGD occurs all along its southern boundary and it is covered by fine-grained sediments that are frequently resuspended due to vessel maneuvering. Comprehensive seasonal Ra mass balances were constructed for the waters of the Port of Maó using both short-lived (224Ra) and long-lived (228Ra) Ra isotopes. SGD flows to the Port of Maó obtained by using 228Ra revealed a seasonal pattern, likely dominated by the recharge cycle, with maximum SGD rates during the wet seasons ((180 ± 100) · 103 m3·day− 1 in fall) and minimum flows during summer ((56 ± 35) · 103 m3·day− 1). The results also showed that the Ra flux from bottom sediments, through diffusion and due to releases associated to resuspension events, represented a significant source of Ra to the harbor waters. This sedimentary source accounted for a major fraction of the 224Ra supplied to the system (30-90%, depending on the season), whereas the sediment influence on the 228Ra mass balance was significantly lower (10-40%) due to its slower production rate. These findings suggested that attributing Ra inputs to the water column solely to SGD in systems covered by fine-grained sediments and/or affected by processes that favor Ra exchange across the sediment-water interface might not be accurate, requiring a detailed evaluation of the sediment sources. The inputs from sediments are often difficult to quantify, but using long-lived Ra isotopes to estimate the SGD flow may minimize the effect of a poor characterization of the sediment source.
Grants:	Ministerio de Ciencia e Innovación CTM2009-08270 Ministerio de Ciencia e Innovación AP2008-03044 Agència de Gestió d'Ajuts Universitaris i de Recerca 2014/SGR-1356
Rights:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, i la comunicació pública de l'obra, sempre que no sigui amb finalitats comercials, i sempre que es reconegui l'autoria de l'obra original. No es permet la creació d'obres derivades.
Language:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Subject:	Radium isotopes ; Submarine Groundwater Discharge ; Sediments ; Mediterranean Sea
Published in:	Marine Chemistry, Vol. 171 (April 2015) , p. 107-117, ISSN 0304-4203

DOI: 10.1016/j.marchem.2015.02.010

49 p, 14.9 MB

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Research literature > UAB research groups literature > Research Centres and Groups (research output) > Experimental sciences > Institut de Ciència i Tecnologia Ambientals (ICTA)
Articles > Research articles
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