title: Submarine groundwater discharge as a major source of nutrients to the Mediterranean Sea.
abstract: The Mediterranean Sea (MS) is a semienclosed basin that is considered one of the most oligotrophic seas in the world. In such an environment, inputs of allochthonous nutrients and micronutrients play an important role in sustaining primary productivity. Atmospheric deposition and riverine runoff have been traditionally considered the main external sources of nutrients to the MS, whereas the role of submarine groundwater discharge (SGD) has been largely ignored. However, given the large Mediterranean shore length relative to its surface area, SGD may be a major conveyor of dissolved compounds to the MS. Here, we used a (228)Ra mass balance to demonstrate that the total SGD contributes up to (0.3-4.8)⋅10(12) m(3) ⋅ y(-1) to the MS, which appears to be equal or larger by a factor of 16 to the riverine discharge. SGD is also a major source of dissolved inorganic nutrients to the MS, with median annual fluxes of 190⋅10(9), 0.7⋅10(9), and 110⋅10(9) mol for nitrogen, phosphorous, and silica, respectively, which are comparable to riverine and atmospheric inputs. This corroborates the profound implications that SGD may have for the biogeochemical cycles of the MS. Inputs of other dissolved compounds (e.g., iron, carbon) via SGD could also be significant and should be investigated.
authors.affiliation: Institut de Ciència i Tecnologia Ambientals and valenti.rodellas@uab.cat jordi.garcia@uab.cat.
authors.forename: Valentí
authors.identifier: http://orcid.org/0000-0002-5896-9987
authors.initials: V
authors.lastname: Rodellas
authors.affiliation: Institut de Ciència i Tecnologia Ambientals and Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain; valenti.rodellas@uab.cat jordi.garcia@uab.cat.
authors.forename: Jordi
authors.initials: J
authors.lastname: Garcia-Orellana
authors.affiliation: Institut de Ciència i Tecnologia Ambientals and Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain; Oceans Institute and School of Physics, The University of Western Australia, Crawley, WA 6009, Australia; School of Natural Sciences and Centre for Marine Ecosystems Research, Edith Cowan University, Joondalup, WA 6027, Australia; and.
authors.forename: Pere
authors.initials: P
authors.lastname: Masqué
authors.affiliation: Department of Geography and Environment, Bar-Ilan University, Ramat-Gan 52900, Israel.
authors.forename: Mor
authors.initials: M
authors.lastname: Feldman
authors.affiliation: Department of Geography and Environment, Bar-Ilan University, Ramat-Gan 52900, Israel.
authors.forename: Yishai
authors.initials: Y
authors.lastname: Weinstein
mesh_terms: D001272:Atmosphere; D004784:Environmental Monitoring / Q000379:methods; D060587:Groundwater / Q000737:chemistry*; D008522:Mediterranean Sea; D009584:Nitrogen / Q000737:chemistry*; D010758:Phosphorus / Q000737:chemistry*; D011868:Radioisotopes / Q000737:chemistry; D011883:Radium / Q000737:chemistry; D045483:Rivers; D012623:Seawater / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D013051:Spectrometry, Gamma; D014872:Water Movements
chemical_list: D011868:Radioisotopes; D010758:Phosphorus; D012822:Silicon Dioxide; D009584:Nitrogen; D011883:Radium
keywords: Mediterranean Sea; nutrients; radium; submarine groundwater discharge