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  • 1.
    Charette, M
    et al.
    Woods Hole Oceanographic Institution, USA.
    Lam, P.J.
    University of California Santa Cruz, USA.
    Lohan, M.C.
    University of Southhampton, UK.
    Kwon, E.Y.
    Seoul National University,Korea.
    Hatje, V
    Universidade Federal da Bahia, Brazil.
    Jeandel, C
    University of Toulouse, France.
    Shiller, A.M.
    University of Southern Mississippi, USA.
    Cutter, G.A.
    Old Dominion University, USA.
    Thomas, A
    University of Edinburgh, UK.
    Boyd, P.W.
    University of Tasmania, Australia.
    Homoky, W.B.
    University of Oxford, UK.
    Milne, A.
    Plymoth University, UK.
    Thomas, H.
    Dalhousie University, Canada.
    Andersson, P.S.
    Swedish Museum of Natural History, Department of Geology.
    Porcelli, D.
    University of Oxford,Uk.
    Tanaka, T
    University of Tokyo, Japan.
    Geibert, W
    Alfred Wegener Institute, Germany.
    Dehairs, F.
    Vrije Universiteit, Belgium.
    Garcia-Orellana, J.
    Universitat Autonoma de Barcelona, Spain.
    Coastal ocean and shelf-sea biogeochemical cycling of trace elements and isotopes: lessons learned from GEOTRACES2016In: Philosopical Transactions of the Royal Society A, ISSN 1364–503X, Vol. 374, no 2081Article, review/survey (Refereed)
    Abstract [en]

    Continental shelves and shelf seas play a central role in the global carbon cycle. However,

    their importance with respect to trace element and isotope (TEI) inputs to ocean basins

    is less well understood. Here, we present major findings on shelf TEI biogeochemistry

    from the GEOTRACES programme as well as a proof of concept for a new method to

    estimate shelf TEI fluxes. The case studies focus on advances in our understanding of TEI

    cycling in the Arctic, transformations within a major river estuary (Amazon), shelf sediment

    micronutrient fluxes and basin-scale estimates of submarine groundwater discharge. The

    proposed shelf flux tracer is 228-radium (T1/2 =5.75 yr), which is continuously supplied to

    the shelf from coastal aquifers, sediment porewater exchange and rivers. Model-derived shelf

    228Ra fluxes are combined with TEI/ 228Ra ratios to quantify ocean TEI fluxes from the

    western North Atlantic margin. The results from this new approach agree well with previous

    estimates for shelf Co, Fe, Mn and Zn inputs and exceed published estimates of atmospheric

    deposition by factors of approximately 3–23. Lastly, recommendations are made for additional

    GEOTRACES process studies and coastal margin-focused section cruises that will help refine

    the model and provide better insight on the mechanisms driving shelf-derived TEI fluxes

    to the ocean.

    This article is part of the themed issue ‘Biological and climatic impacts of ocean trace element

    chemistry’.

  • 2.
    Chi Fru, Ernest
    et al.
    Stockholm University, Department of Geological Sciences.
    Rodríguez, Nathalie
    Stockholm University Department of Geological Sciences.
    Partin, Camille
    University of Saskatchewan, Canada.
    Lalonde, Stefan
    Université de Bretagne Occidentale, France.
    Andersson, Per
    Swedish Museum of Natural History, Department of Geology.
    Weiss, Dominik
    Imperial College, London, UK.
    El Albani, Abderrazak
    Université de Poitiers, France.
    Rodushkin, Ilia
    ALS Scandinavia, Sweden.
    Konhauser, Kurt
    University of Alberta, Canada.
    Cu isotopes in marine black shales record the Great Oxidation Event2016In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 113, no 18, p. 4941-4946Article in journal (Refereed)
    Abstract [en]

    The oxygenation of the atmosphere ∼2.45–2.32 billion years ago (Ga) is one of the most significant geological events to have affected Earth’s redox history. Our understanding of the timing and processes surrounding this key transition is largely dependent on the development of redox-sensitive proxies, many of which remain unexplored. Here we report a shift from negative to positive copper isotopic compositions (δ65CuERM-AE633) in organic carbon-rich shales spanning the period 2.66–2.08 Ga. We suggest that, before 2.3 Ga, a muted oxidative supply of weathering-derived copper enriched in 65Cu, along with the preferential removal of 65Cu by iron oxides, left seawater and marine biomass depleted in 65Cu but enriched in 63Cu. As banded iron formation deposition waned and continentally sourced Cu became more important, biomass sampled a dissolved Cu reservoir that was progressively less fractionated relative to the continental pool. This evolution toward heavy δ65Cu values coincides with a shift to negative sedimentary δ56Fe values and increased marine sulfate after the Great Oxidation Event (GOE), and is traceable through Phanerozoic shales to modern marine settings, where marine dissolved and sedimentary δ65Cu values are universally positive. Our finding of an important shift in sedimentary Cu isotope compositions across the GOE provides new insights into the Precambrian marine cycling of this critical micronutrient, and demonstrates the proxy potential for sedimentary Cu isotope compositions in the study of biogeochemical cycles and oceanic redox balance in the past.

  • 3.
    Conrad, Sarah
    et al.
    Luleå University of Technology.
    Ingri, Johan
    Luleå University of Technology.
    Gelting, Johan
    Leleå University of Technology.
    Nordblad, Fredrik
    Luleå University of Technology.
    Engström, Emma
    Luleå University of Technology.
    Rodushkin, Ilia
    ALS Laboratory Group, Luleå.
    Andersson, Per
    Swedish Museum of Natural History, Research Division.
    Porcelli, Don
    Oxford University, Oxford.
    Gustafsson, Örjan
    Stockholm University, Stockholm.
    Semiletov, Igor
    University of Alaska, USA.
    Öhlander, Björn
    Luleå University of Technology.
    Distributionof Fe isotopes in particles and colloids in the salinity gradient along theLena River plume, Laptev Sea2019In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 16, p. 1305-1319Article in journal (Refereed)
    Abstract [en]

    Riverine Fe input is the primary Fe source to the ocean. This study is focused on the distribution of Fe along the Lena River freshwater plume in the Laptev Sea using samples from a 600 km long transect in front of the Lena River mouth. Separation of the particulate (>0.22µm), colloidal (0.22µm – 1kDa), and truly dissolved (<1kDa) fractions of Fe was carried out. The total Fe concentrations ranged from 0.15 to 57 µM with Fe dominantly as particulate Fe. The loss of > 99% of particulate Fe and about 90% of the colloidal Fe was observed across the shelf, while the truly dissolved phase was almost constant across the Laptev Sea. Thus, the truly dissolved Fe could be an important source of bioavailable Fe for plankton in the central Arctic Ocean, together with the colloidal Fe. Fe-isotope analysis showed that the particulate phase and the sediment below the Lena River freshwater plume had negative δ56Fe values (relative to IRMM-14). The colloidal Fe phase showed negative δ56Fe values close to the river mouth (about -0.20‰) and positive δ56Fe values in the outermost stations (about +0.10‰).

    We suggest that the shelf zone acts as a sink for Fe particles and colloids with negative δ56Fe values, representing chemically reactive ferrihydrites. While the positive δ56Fe values of the colloidal phase within the outer Lena River freshwater plume, might represent Fe-oxyhydroxides, which remain in the water column, and will be the predominant δ56Fe composition in the Arctic Ocean.

  • 4.
    Cornacchia, Irene
    et al.
    Dipartimento di Scienze della Terra, Sapienza Universita di Roma.
    Andersson, Per
    Swedish Museum of Natural History, Department of Geology.
    Agostine, Samuele
    Instituto di Geosciencze e Georisorse, CNR, Pisa.
    Brandanao, Marco
    Dipartimento di Scienze della Terra, Sapienza Universita di Roma.
    Strontium stratigraphy of the upper Miocene Lithothamnion Limestone in the Majella Mountain, central Italy, and its palaeoenvironmental implications2017In: Lethaia: an international journal of palaeontology and stratigraphy, ISSN 0024-1164, E-ISSN 1502-3931, Vol. 50, no 4, p. 561-575Article in journal (Refereed)
    Abstract [en]

    The87Sr/86Sr isotope ratio has been widely used as aphysical tool to date and correlate carbonate successions due to the long Srresidence time in comparison with the ocean mixing time. If this method workson oceanic successions, marginal basins may show different Sr isotope recordsin comparison with the coeval ocean one due to sea-level variations,continental run-off and restricted water exchanges. In this work, we present the87Sr/86Sr isotope record of the upper Miocene carbonateramp of the Lithothamnion Limestone(Majella Mountain, central Apennines), as an example of the onset of restrictedwater exchanges between a marginal basin and the ocean water masses. The overalllatemost Tortonian–earlyMessinian Sr isotope record of the Lithothamnion Limestonefits below the global reference line. This deviation has been interpreted as dueto the strong control that freshwater input and enhanced continental run-off,linked to the migration of the Apennine accretionary wedge and foredeep system,have had on the central Adriatic water chemistry. These results imply that anaccurate oceanographic and geodynamic framework along with diagenetic overprintinvestigation has to be taken into consideration prior to apply SIS oncarbonate successions on marginal basins, even when facies analyses indicatefully marine conditions. This seems to be the case for the upper MioceneCentral Mediterranean carbonate successions, but may have more general validityand be extended to other recent or past marginal basins.

  • 5.
    Cuss, Chad
    et al.
    Trent University Canada.
    Guéguen, Celine
    Trent University Canada.
    Andersson, Per
    Swedish Museum of Natural History, Department of Geology.
    Porcelli, Don
    University of Oxford UK.
    Maximov, Trofim
    North-Eastern Federal University Yakutsk, Russia.
    Kutscher, Liselott
    Swedish Museum of Natural History, Department of Geology.
    Advanced residuals analysis for determining the number of PARAFAC components in dissolved organic matter2016In: Applied Spectroscopy, ISSN 0003-7028, E-ISSN 1943-3530, Vol. 70, no 2, p. 334-346Article in journal (Refereed)
  • 6.
    Delmonte, B
    et al.
    University Milano-Bicocca, Milano, Italy.
    Paleari, C. I.
    University Milano-Bicocca, Milano, Italy.
    Andò, S
    University Milano-Bicocca, Milano, Italy.
    Garzantini, E
    University Milano-Bicocca, Milano, Italy.
    Andersson, Per Sune
    Swedish Museum of Natural History, Department of Geology.
    Petit, J.R.
    University of Grenobles, Grenoble, France.
    Crosta, X
    Unversity of Bordeaux, St Hilaire, France.
    Narcisi, B
    ENEA, Rome, Italy.
    Baroni, C
    University of Pisa, Pisa, Italy.
    Salvatore, M.C.
    University of Pisa, Pisa, Italy.
    Baccolo, G.
    University Milano-Bicocca, Milano, Italy.
    Maggi, Valter
    University Milano-Bicocca, Milano, Italy.
    Causes of dust size variability in central East Antarctica (Dome B):Atmospheric transport from expanded South American sources during Marine Isotope Stage 22017In: Quaternary Science Reviews, ISSN 0277-3791, E-ISSN 1873-457X, Vol. 168, p. 55-68Article in journal (Refereed)
    Abstract [en]

    We here investigate the spatial and temporal variability of eolian dust particle sorting recorded in the Dome B (77 05 S, 94 55 E) ice core, central East Antarctica, during Marine Isotope Stage (MIS) 2. We address the question whether such changes reflect variable transport pathways from a unique source area or rather a variable apportionment from diverse Southern Hemisphere sources transported at different elevation in the troposphere. The Sr-Nd radiogenic isotope composition of glacial dust samples as well as single-particle Raman mineralogy support the hypothesis of a single dust provenance both for coarse and fine mode dust events at Dome B. The southern South American provenance of glacial dust in Antarctica deduced from these results indicate a dust composition coherent with a mixture of volcanic material and minerals derived from metamorphic and plutonic rocks. Additionally, Dome B glacial samples contain aragonite particles along with diatom valves of marine benthic/epiphytic species and freshwater species living today in the northern Antarctic Peninsula and southern South America. These data suggest contribution from the exposed Patagonian continental shelf and glacial outwash plains of southern Patagonia at the time when sea level reached its minimum. Our results confirm that dust sorting is controlled by the relative intensity of the two main patterns of tropospheric dust transport onto the inner Plateau, i.e. fast low-level advection and long-range high-altitude transport including air subsidence over Antarctica.

  • 7.
    Fehr, Manuela A.
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Andersson, Per S.
    Swedish Museum of Natural History, Department of Geology.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Gustafsson, Örjan
    Stockholms universitet.
    Mörth, Carl-Magnus
    Stockholms universitet.
    Iron enrichments and Fe isotopic compositions of surface sediments from the Gotland Deep, Baltic Sea2010In: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 277, p. 310-322Article in journal (Refereed)
  • 8.
    Fehr, Manuela
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Andersson, Per S.
    Swedish Museum of Natural History, Department of Geology.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Mörth, Carl-Magnus
    Stockholms universitet.
    Iron isotope variations in Holocene sediments of the Gotland deep, Baltic Sea2008In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 72, p. 807-826Article in journal (Refereed)
  • 9.
    Fornander, Elin
    et al.
    Stockholm University.
    Lidén, Kerstin
    Stockholm University.
    Eriksson, Gunilla
    Stockholm University.
    Andersson, Per
    Swedish Museum of Natural History, Department of Geology.
    Identifying mobility in populations with mixed marine/terrestrial diets: strontium isotope analyses of skeletal material from a passage grave in Resmo, Öland, Sweden2015In: Forging Identities. The Mobility of Culture in Bronze Age Europe: Report from a Marie Curie Project 2009-2012 with concluding conference at Aarhus University, Moesgaard, 2012, Volume 1 / [ed] Paulina Suchowska-Ducke, Samantha Scott Reiter, Helle Vandkilde, Oxford: British Archeological Reports , 2015, p. 183-192Chapter in book (Refereed)
    Abstract [en]

    Strontium isotope analysis of skeletal material as a means to reconstruct prehistoric residential patterns has previously mainly been applied to populations with terrestrial diets. Here we present a model for populations with mixed marine/terrestrial diets, which is based on two-component mixing of strontium isotopes. Applying this model, we can estimate the original strontium isotope value of the terrestrial component of the diet. Accordingly it is possible to identify non-local individuals even if they had a mixed marine/terrestrial diet. The model is applied to tooth enamel samples representing nine individuals recovered from a passage grave in Resmo, on the island of Öland in the Baltic Sea, where at least five non-local individuals, representing at least two different geographical regions of origin, were identified. Non-local individuals were more frequent during the Bronze Age than during previous phases.

  • 10.
    Gdaniec, Sandra
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Roy-Barman, Matthieu
    Laboratoire des Sciences du Climat et de l'Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay,Gif-sur-Yvette, France.
    Foliot, Lorna
    Laboratoire des Sciences du Climat et de l'Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay,Gif-sur-Yvette, France.
    Thil, Francois
    Laboratoire des Sciences du Climat et de l'Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay,Gif-sur-Yvette, France.
    Dapoigny, Arnaud
    Laboratoire des Sciences du Climat et de l'Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay,Gif-sur-Yvette, France.
    Burckel, Pierre
    Laboratoire des Sciences du Climat et de l'Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay,Gif-sur-Yvette, France.
    Garcia-Orellana, Jordi
    Institut de Ciència i Tecnologia Ambientals & Departament de Física, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain.
    Masqué, Pere
    Institut de Ciència i Tecnologia Ambientals & Departament de Física, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain.
    Mörth, Carl-Magnus
    Stockholm University, Department of Geological sciences, Stockholm, Sweden.
    Andersson, Per
    Swedish Museum of Natural History, Department of Geology.
    Thorium and Protactinium isotopes as tracers of marine particle fluxes and deep water circulation in the Mediterranean Sea2018In: Marine Chemistry, ISSN 0304-4203, E-ISSN 1872-7581, Vol. 199, p. 12-23Article in journal (Refereed)
    Abstract [en]

    231Pa, 230Th and 232Th were analyzed in unfiltered sea water samples (n = 66) and suspended particles (n = 19) collected in the Mediterranean Sea during the MedSeA-GA04-S cruise along the GEOTRACES section GA04S and used to investigate mechanisms controlling the distribution and fractionation of Pa and Th in an ocean margin environment. 231Pa and230Th are particle reactive radionuclides and are often used astracers of processes such as boundary scavenging, particle transport and ocean circulation. The depth profiles of total 231Pa and 230Th concentrations in the Mediterranean Sea displayed non-linear shapes. Higher total 232Th concentrations were observed at the straits and in deepwaters pointing at lithogenic sources. Fractionation factors FTh/Pa ranged from 1.4 to 9. Application of a box-model illustrated that 94 % of the 231Pa and almost all of the 230Th (99.9 %) produced in the Mediterranean Sea is removed to the sediment by scavenging. The negligible export of 230Th to the Atlantic Ocean, leads to a reevaluation of the mean settling speed of the filtered particles, which is now estimated to 500-1000 m/y. The low FTh/Pa fractionation factors are attributed to the efficient scavenging and lack of transport of 231Pa to the Atlantic Ocean.

  • 11.
    Grasse, P.
    et al.
    GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany.
    Brezezinski, M.
    Marine Science Institute and the Department of Ecology, Evolution, and Marine Biology & University of California, USA.
    Cardinal, D.
    Sorbonne Universités, Paris, France.
    de Souza, G.F.
    ETH Zurich, Institute of Geochemistry and Petrology, Switzerland.
    Andersson, Per
    Swedish Museum of Natural History, Department of Geology.
    Closset, I.
    Sorbonne Universités, Paris, France.
    Cao, Z.
    State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China.
    Dai, M.
    State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China.
    Ehlert, C.
    Max Planck Research Group for Marine Isotope Geochemistry, University of Oldenburg, Germany.
    Estrade, N.
    University of British Columbia, Vancouver, British Columbia,.
    Francois, R.
    University of British Columbia, Vancouver, British Columbia,.
    Frank, M.
    GEOMAR, Helmholtz Centre for Ocean Research Kiel, Germany.
    Jiang, G.
    Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China.
    Jones, J.L.
    Marine Science Institute and the Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara USA.
    Kooijman, E.
    Swedish Museum of Natural History, Department of Geology.
    Liu, Q.
    Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China.
    Lu, D.
    Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China.
    Pahnke, K.
    Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, Germany.
    Ponzevera, E.
    Unité de Recherche Géosciences Marines, IFREMER, Brest, France.
    Schmitt, M.
    Swedish Museum of Natural History, Department of Geology.
    Sun, S.
    Department of Environmental Science and Analytical Chemistry, Stockholm University, Sweden.
    Sutton, J.N.
    Universite de Brest, CNRS, IRD, IFREMER, LEMAR, IUEM, France.
    Thil, F.
    LSCE/IPSL - Laboratoire des Sciences du Climat et de l'Environnement, Gif sur Yvette, France.
    Weis, D.
    University of British Columbia Pacific Center for Isotopic and Geochemical Research, Vancouver, British Columbia,Canada .
    Wetzel, F.
    ETH Zurich, Institute of Geochemistry and Petrology, Switzerland.
    Zhang, A.
    State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, China.
    Zhang, J.
    State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, China.
    Zhang, Z.
    State Key Laboratory of Marine Environmental Science,Xiamen University,.
    GEOTRACES Intercalibration of the Stable Silicon Isotope Composition of Dissolved Silicic Acid in Seawater2017In: Journal of Analytical Atomic Spectrometry, ISSN ISSN 0267-9477, Vol. 32, p. 562-578Article in journal (Refereed)
    Abstract [en]

    The first inter-calibration study of the stable silicon isotope composition of dissolved silicic acid in seawater, d30Si(OH)4, is presented as a contribution to the international GEOTRACES program. Eleven laboratories from seven countries analyzed two seawater samples from the North Pacific subtropical gyre (Station ALOHA) collected at 300 m and at 1000 m water depth. Sampling depths were chosen to obtain samples with a relatively low (9 mmol L-1, 300 m) and a relatively high (113 mmol L-1, 1000 m) silicic acid concentration as sample preparation differs for low- and high concentration samples. Data for the 1000 m water sample were not normally distributed so the median is used to represent the central tendency for the two samples. Median d30Si(OH)4 values of +1.66‰ for the low-concentration sample and +1.25‰ for the high-concentration sample were obtained. Agreement among laboratories is overall considered very good; however, small but statistically significant differences among the mean isotope values obtained by different laboratories were detected, likely reflecting inter-laboratory differences in chemical preparation including preconcentration and purification methods together with different volumes of seawater analyzed, andthe use of different mass spectrometers including the Neptune MC-ICP-MS (Thermo Fisher™, Germany), the Nu Plasma MC-ICP-MS (Nu Instruments™, Wrexham, UK), and the Finnigan™ (now Thermo Fisher™, Germany) MAT 252 IRMS. Future studies analyzing d30Si(OH)4 in seawater should also analyze and report values for these same two reference waters in order to facilitate comparison of data generated among and within laboratories over time.

  • 12.
    Gustafsson, Örjan
    et al.
    Department of Environmental Science and Analytical Chemistry Stockholm University.
    Gelting, Johan
    Department of Environmental Science and Analytical Chemistry.
    Andersson, Per
    Swedish Museum of Natural History, Department of Geology.
    Larsson, Ulf
    Department of Ecology, Environment and Plant Sciences, Stockholm University.
    Roos, Per
    Department of Nuclear Technologies, Technical University of Denmark.
    An assessment of upper ocean carbon and nitrogen export fluxes on the boreal continental shelf: A 3-year study in the open Baltic Sea comparing sediment traps, 234Th proxy, nutrient, and oxygen budgets2013In: Limnology and Oceanography: Methods, ISSN 1541-5856, E-ISSN 1541-5856, ISSN 1541-5856, Vol. 11, no 9, p. 495-510, article id DOI: 10.4319/lom.2013.11.495Article in journal (Refereed)
  • 13. Hirst, Catherine
    et al.
    Andersson, Per
    Swedish Museum of Natural History, Research Division.
    Kooijman, Ellen
    Swedish Museum of Natural History, Department of Geology.
    Schmitt, Melanie
    Swedish Museum of Natural History, Department of Geology.
    Kutscher, Liselott
    Maximov, Trofim
    Mörth, Carl-Magnus
    Porcelli, Don
    Iron isotopes reveal the sources of Fe-bearing particles and colloids in the Lena River basin2019In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533Article in journal (Refereed)
  • 14.
    Hirst, Catherine
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Andersson, Per
    Swedish Museum of Natural History, Department of Geology.
    Shaw, Samuel
    University of Manchester.
    Burke, Ian
    University of Leeds.
    Kutscher, Liselott
    Swedish Museum of Natural History, Department of Geology.
    Murphy, Melissa
    Oxford University.
    Maximov, Trofim
    Institute for Biological Problems of the Cryolithozone, Siberian Branch of the Russian Academy of Sciences, Yakutsk.
    Pokrovsky, Oleg
    University of Toulouse.
    Mörth, Carl-Magnus
    Stockholm University.
    Porcelli, Don
    Oxford University.
    Characterisation of Fe-bearing particles and colloids in the Lena River basin, NE Russia2017In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 213, p. 553-573Article in journal (Refereed)
    Abstract [en]

    Rivers are significant contributors of Fe to theocean. However, the characteristics of chemically reactive Fe remain poorly constrained, especially in large Arctic rivers, which drain landscapes highly susceptible to climate change and carbon cycle alteration. The aim of this study was a detailed characterisation (size, mineralogy, and speciation) of riverine Fe-bearing particles (> 0.22 µm) and colloids (1 kDa – 0.22 µm) and their association with organic carbon (OC), in the Lena River and tributaries, which drain a catchment almost entirely underlain by permafrost. Samples fromthe main channel and tributaries representing watersheds that span a wide rangein topography and lithology were taken after the spring flood in June 2013 and summer baseflow in July 2012. Fe-bearing particles were identified, usingTransmission Electron Microscopy, as large (200 nm – 1 µm) aggregates of smaller (20 nm - 30 nm) spherical colloids of chemically-reactive ferrihydrite.In contrast, there were also large (500 nm – 1 µm) aggregates of clay (illite) particles and smaller (100 - 200 nm) iron oxide particles (dominantly hematite) that contain poorly reactive Fe. TEM imaging and Scanning Transmission X-raymicroscopy (STXM) indicated that the ferrihydrite is present as discrete particles within networks of amorphous particulate organic carbon (POC) and attached to the surface of primary produced organic matter and clay particles.Together, these larger particles act as the main carriers of nanoscale ferrihydrite in the Lena River basin.  The chemically reactive ferrihydrite accounts for on average 70 ± 15 % of the total suspended Fe in the Lena River and tributaries. These observations place important constraints on Fe and OC cycling in the Lena River catchment area and Fe-bearing particle transport to the Arctic Ocean.

  • 15.
    Horst, Axel
    et al.
    Stockholm University.
    Holmstrand, Henry
    Stockholm University.
    Andersson, Per
    Swedish Museum of Natural History, Department of Geology.
    Thornton, Brett F
    Stockholm University.
    Wishkerman, Asher
    Max-Planck-Institute for Chemistry, Germany.
    Keppler, Frank
    Max-Planck-Institute for Chemistry, Germany.
    Gustafsson, Örjan
    Stockholm University.
    Stable bromine isotopic composition of methyl bromide released from plant matter2014In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 125, p. 186-195Article in journal (Refereed)
  • 16.
    Krall, Lindsay
    et al.
    The Swedish Nuclear Fuel and Waste Management Company.
    Trezzi, Giada
    Universitat Autònoma de Barcelona.
    Garcia-Orellana, Jordi
    Universitat Autònoma de Barcelona.
    Valenti, Rodellas
    CEREGE, Aix-Marseille Université.
    Mörth, Magnus
    Department of Geological Sciences Stockholm University.
    Andersson, Per
    Swedish Museum of Natural History, Department of Geology.
    Submarine groundwater discharge at Forsmark, Gulf of Bothnia, providedby Ra isotopes2017In: Marine Chemistry, ISSN 0304-4203, E-ISSN 1872-7581, Vol. 196, p. 162-172Article in journal (Refereed)
    Abstract [en]

    Submarine groundwater discharge (SGD) to the Gulf of Bothnia, Baltic Sea, has been believed to be insignificant from hydrological models, yet geochemical investigations of SGD in this basin are limited. In this study, 223Ra, 224Ra, 226Ra, and 228Ra have been complemented by stable δ18O and d2H isotopes to characterize and quantify SGD rates from the coast of Forsmark, Sweden to Öregrundsgrepen Strait (Gulf of Bothnia). In shallow bays, SGD has been traced using relations between Ra, d2H and d18O isotopes and salinity. Zonal SGD from deformation zones, expressed as hydraulically conductive fractures, overlain by the Börstilåsen esker, a strip of conductive gravel sediment, have been traced through offshore 224Raxs and 226Ra trends. On the basis of a 224Raxs mass balance, the SGD flow rate ranges from (5.5 ± 3.0) · 103 m3 d-1 to (950 ± 520) · 103 m3 d-1. These rates are up to two orders of magnitude higher than those determined from local hydrological models, which consider only the fresh component of SGD. From the divergence between the hydrological and 224Raxs models, it is inferred that the site is influenced by a component of recirculated seawater.

  • 17.
    Kutscher, Liselott
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Mörth, Carl-Magnus
    Stockholm University.
    Porcelli, Don
    University of Oxford.
    Hirst, Catherine
    Swedish Museum of Natural History, Department of Geology.
    Maximov, Trofim
    North Eastern Federal University, Yakutsk, Russia.
    Petrov, Roman
    North Eastern Federal University, Yakutsk, Russia.
    Andersson, Per
    Swedish Museum of Natural History, Department of Geology.
    Spatial variation in concentration and sources of organic carbon in the Lena River, Siberia2017In: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 122Article in journal (Refereed)
    Abstract [en]

    Global warming in permafrost areas is expected to change fluxes of riverine organic carbon (OC) 22 to the Arctic Ocean. Here OC concentrations, stable carbon isotope signatures (δ13C) and carbon-23 nitrogen ratios (C/N) are presented from 22 sampling stations in the Lena River and 40 of its 24 tributaries. Sampling was conducted during two expeditions: the first in July 2012 in the south 25 and southeastern region and the second in June 2013 in the northern region of the Lena basin. 26 The data showed significant spatial differences in concentrations and major sources of OC. Mean 27 sub-catchment slopes were correlated with OC concentrations, implying that mountainous areas 28 in general had lower concentrations than lowland areas. δ13C and C/N data from tributaries 29 originating in mountainous areas indicated that both dissolved and particulate OC (DOC and 30 POC) were mainly derived from soil organic matter (SOM). In contrast, tributaries originating in 31 lowland areas had larger contributions from fresh vegetation to DOC, while aquatically produced 32 OC was the major source of POC. We suggest that these differences in dominant sources 33 indicated differences in dominant flow pathways. Tributaries with larger influence of fresh 34 vegetation probably had surficial flow pathways, while tributaries with more SOM influence had 35 deeper water flow pathways. Thus, the future export of OC to the Arctic Ocean will likely be 36 controlled by changes in spatial patterns in hydroclimatology and the depth of the active layers 37 influencing the dominant water flow pathways in Arctic river basins.

  • 18.
    Murphy, Melissa
    et al.
    University of Oxford.
    Porcelli, Don
    University of Oxford.
    Pogge von Strandmann, Philip
    University College London.
    Hirst, Catherine
    Swedish Museum of Natural History, Department of Geology.
    Kutscher, Liselott
    Swedish Museum of Natural History, Department of Geology.
    Katchinoff, Joachim
    Yale University.
    Mörth, Carl-Magnus
    Stockholm University.
    Maximov, Trofim
    Institute for Biological Problems in the Cryolitic Zone, Yakutsk.
    Andersson, Per
    Swedish Museum of Natural History, Research Division.
    Tracingsilicate weathering processes in the permafrost-dominated Lena River watershedusing lithium isotopes2019In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 245, p. 154-171Article in journal (Refereed)
    Abstract [en]

    Increasing global temperatures are causing widespread changes in the Arctic, including permafrost thawing and altered freshwater inputs and trace metal and carbon fluxes into the ocean and atmosphere. Changes in the permafrost active layer thickness can affect subsurface water flow paths and water-rock interaction times, and hence weathering processes. Riverine lithium isotope ratios (reported as δ7Li) are tracers of silicate weathering that are unaffected by biological uptake, redox, carbonate weathering and primary lithology. Here we use Li isotopes to examine silicate weathering processes in one of the largest Russian Arctic rivers: the Lena River in eastern Siberia. The Lena River watershed is a large multi-lithological catchment, underlain by continuous permafrost. An extensive dataset of dissolved Li isotopic compositions of waters from the Lena River main channel, two main tributaries (the Aldan and Viliui Rivers) and a range of smaller sub tributaries are presented from the post-spring flood/early-summer period at the onset of active layer development and enhanced water-rock interactions. The Lena River main channel (average δ7Lidiss ~19‰) has a slightly lower isotopic composition than the mean global average of 23‰ (Huh

    et al., 1998a). The greatest range of [Li] and δ7Lidiss are observed in catchments draining the south facing slopes of the Verkhoyansk Mountain Range. South-facing slopes in high-latitude, permafrost dominated regions are typically characterised by increased summer insolation and higher daytime temperatures relative to other slope aspects. The increased solar radiation on south-facing catchments promotes repeated freeze-thaw cycles, and contributes to more rapid melting of snow cover, warmer soils, and increased active layer thaw depths. The greater variability in δ7Li and [Li] in the south-facing rivers likely reflect the greater infiltration of melt water and enhanced water rock interactions within the active layer. A similar magnitude of isotopic fractionation is observed between the low-lying regions of the Central Siberian Plateau (and catchments draining into the Viliui River), and catchments draining the Verkhoyansk Mountain Range into the Aldan River. This is in contrast to global rivers in non permafrost terrains that drain high elevations or areas of rapid uplift, where high degrees of physical erosion promote dissolution of freshly exposed primary rock typically yielding low δ7Lidiss, and low lying regions exhibit high riverine δ7Li values resulting from greater water-rock interaction and formation of secondary mineral that fractionates Li isotopes. Overall, the range of Li concentrations and δ7Lidiss observed within the Lena River catchment are comparable to global rivers located in temperate and tropical regions. This suggests that cryogenic weathering features specific to permafrost regions (such as the continual exposure of fresh primary minerals due to seasonal freeze-thaw cycles, frost shattering and salt weathering), and climate (temperature and runoff), are not a dominant control on δ7Li variations. Despite vastly different climatic and weathering regimes, the same range of riverine δ7Li values globally suggests that the same processes govern Li geochemistry – that is, the balance between primary silicate mineral dissolution and the formation (or exchange with) secondary minerals. This has implications for the use of δ7Li as a palaeo weathering tracer for interpreting changes in past weathering regimes.

  • 19.
    Ning, Wenxin
    et al.
    Department of Geology Lund University.
    Andersson, Per S
    Swedish Museum of Natural History, Department of Geology.
    Ghosh, Anupam
    Dept. of Geol. Sciences Jadavpur University India.
    Khan, Mansoor
    Department of Geology Lund University.
    Filipsson, Helena
    Department of Geology Lund University.
    Quantitative salinity reconstructions of the Baltic Sea during the mid-Holocene2017In: Boreas, ISSN 0300-9483, E-ISSN 1502-3885, Vol. 46, no 1, p. 100-110Article in journal (Refereed)
  • 20.
    Rosén, Per-Olov
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Andersson, Per
    Swedish Museum of Natural History, Department of Geology.
    Alling, Vanja
    Norwegian Environment Agency.
    Mörth, Carl-Magnus
    Department of Geological Sciences Stockholm University.
    Björk, Göran
    Department of Oceanography Göteborg University.
    Semiletov, Igor
    International Arctic Research Center University of Alaska.
    Porcelli, Don
    Department of Earth Sciences Oxford University.
    Ice export from the Laptev and East Siberian Sea derived from δ18O values2015In: Journal of Geophysical Research - Oceans, ISSN 2169-9275, E-ISSN 2169-9291, ISSN 2169-9275, Vol. 120, no 9, p. 5997-6007, article id 10.1002/2015JC010866Article in journal (Refereed)
  • 21. Sun, Xiaole
    et al.
    Mörth, Carl-Magnus
    Porcelli, Don
    Kutscher, Liselott
    Swedish Museum of Natural History, Department of Geology.
    Hirst, Catherine
    Swedish Museum of Natural History, Department of Geology.
    Murphy, Melissa J.
    Maximov, Trofim
    Petrov, Roman E.
    Humborg, Christoph
    Schmitt, Melanie
    Swedish Museum of Natural History, Department of Geology.
    Andersson, Per
    Swedish Museum of Natural History, Department of Geology.
    Stable silicon isotopic compositions of the Lena River and its tributaries: Implications for silicon delivery to the Arctic Ocean2018In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 241, p. 120-133Article in journal (Refereed)
    Abstract [en]

    Silicon isotope values (d30SiDSi) of dissolved silicon (DSi) have been analyzed in the Lena River and its tributaries, one ofthe largest Arctic watersheds in the world. The geographical and temporal variations of d30SiDSi range from +0.39 to +1.86‰with DSi concentrations from 34 to 121 lM. No obvious patterns of DSi concentrations and d30SiDSi values were observedalong over 200 km of the two major tributaries, the Viliui and Aldan Rivers. In summer, the variations of DSi concentrationsand d30SiDSi values in the water are either caused by biological uptake by higher plants and phytoplankton or by mixing ofwater masses carrying different DSi concentrations and d30SiDSi values. DSi in tributaries from the Verkhoyansk MountainRange seems to be associated with secondary clay formation that increased the d30SiDSi values, while terrestrial biological productionis likely more prevalent in controlling d30SiDSi values in Central Siberian Plateau and Lena Amganski Inter-RiverArea. In winter, when soils were frozen, the d30SiDSi values in the river appeared to be controlled by weathering and clay formationin deep intrapermafrost groundwater. During the spring flood, dissolved silicate materials and phytoliths were flushedfrom the upper thawed soils into rivers, which reset d30SiDSi values to the values observed prior to the biological bloom insummer. The results indicate that the Si isotope values reflect the changing processes controlling Si outputs to the Lena Riverand to the Arctic Ocean between seasons. The annual average d30SiDSi value of the Lena Si flux is calculated to be +0.86± 0.3‰ using measured d30SiDSi values from each season. Combined with the estimate of +1.6 ± 0.25‰ for the Yenisey River,an updated d30SiDSi value of the major river Si inputs to the Arctic Ocean is estimated to be +1.3 ± 0.3‰. This value isexpected to shift towards higher values in the future because of the impacts from a variety of biological and geochemicalprocesses and sources under global warming.

  • 22.
    Sun, Xiaole
    et al.
    Stockholm University.
    Olofsson, Martin
    Linnaeus University Kalmar, Sweden.
    Andersson, Per
    Swedish Museum of Natural History, Department of Geology.
    Fry, Brian
    Griffith University Australia.
    Legrand, Catherine
    Linneaus University Kalmar, Sweden.
    Humborg, Christoph
    Stockholm University.
    Mörth, Carl-Magnus
    Stockholm University.
    Effects of growth and dissolution on the fractionationof silicon isotopes by estuarine diatoms2014In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 130, p. 156-166Article in journal (Refereed)
  • 23.
    Thornton, Brett
    et al.
    Department of Environmental Sciences and Analytical Chemistry, Stockholm University.
    Horst, Axel
    Department of Environmental Sciences and Analytical Chemistry, Stockholm University.
    Carrizo, Daniel
    Department of Environmental Sciences and Analytical Chemistry, Stockholm University.
    Holmstrand, Henry
    Department of Environmental Sciences and Analytical Chemistry, Stockholm University.
    Andersson, Per
    Swedish Museum of Natural History, Department of Geology.
    Crill, Patrick
    Department of Geological Sciences, Stockholm University.
    Gustafsson, Örjan
    Department of Environmental Sciences and Analytical Chemistry, Stockholm University.
    A High-Volume Cryosampler and Sample Purification System for Bromine Isotope Studies of Methyl Bromide2013In: Journal of Atmospheric and Oceanic Technology, ISSN 0739-0572, E-ISSN 1520-0426, ISSN 0739-0572, Vol. 30, no 9, p. 2095-2107Article in journal (Refereed)
  • 24.
    Trezzi, Giada
    et al.
    Universitat Autonoma de Barcelona, Spain.
    Garcia-Orellana, Jordi
    Universitat Autonoma de Barcelona, Spain.
    Rodellas, Valentí
    Universitat Autonoma de Barcelona, Spain.
    Masque, Pere
    Universitat Autonoma de Barcelona, Spain.
    Garcia-Solsona, Ester
    Universitat de Barcelona, Spain.
    Andersson, Per
    Swedish Museum of Natural History, Department of Geology.
    Assessing the role of submarine groundwater discharge as a source of Sr to the Mediterranean Sea2017In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 200, p. 42-54Article in journal (Refereed)
    Abstract [en]

    Submarine groundwater discharge (SGD) has been identified as an

    important source of Sr to the ocean and the SGD-driven Sr flux to the

    global ocean has been recently re-evaluated (Beck et al. 2013). However,

    the uncertainty of this value is still high because of the uncertainties

    related to the determination of SGD flow rates and the paucity of

    87Sr/86Sr data in SGD end-members. As carbonates have high Sr

    concentrations and are subjected to intense heightened weathering, they

    might significantly influence the SGD input of Sr to the ocean. Here we

    present data on Sr concentrations and 87Sr/86Sr ratios in three carbonate

    dominated sites of the western area of the Mediterranean Sea, a semienclosed

    basin characterized by abundant coastal carbonates. The

    87Sr/86Sr ratios in groundwater were lower compared to modern seawater (~

    0.70916), as expected for areas dominated by carbonate lithologies.

    Concentrations of Sr and 87Sr/86Sr ratios in groundwater showed

    conservative mixing in the studied subterranean estuaries. By using SGD

    flow rates reported in the literature for the study areas, a meteoric

    SGD-driven Sr flux of (0.12 - 2.1)·103 mol d-1 km-1 was calculated for

    the region, with a fresh SGD end-member characterized by a Sr

    concentration of 27 - 30 μM and a 87Sr/86Sr ratio of 0.708020 - 0.707834.

    Integrating these Sr data with literature data (i.e. values of Sr

    concentration and 87Sr/86Sr ratio from other lithologies as well as SGD

    flow rates), we also calculated the fresh SGD-driven Sr flux to the

    entire Mediterranean Sea, obtaining a value of (0.34 - 0.83)·109 mol y-1,

    with a 87Sr/86Sr of 0.7086 - 0.7081. Thus, for the entire Mediterranean

    basin, SGD is globally a source of Sr less radiogenic compared to

    seawater. The SGD Sr flux to the Mediterranean Sea represents 5-6% of the

    SGD Sr flux to the global ocean and the Mediterranean SGD end-member has

    higher Sr concentration (5.0 - 12 μM) than the global SGD end-member (2.9

    μM). This confirms the significant role of carbonate lithologies on SGDdriven

    Sr fluxes to seawater.

    The fresh SGD-driven Sr flux to the Mediterranean Sea is about 20 - 50%

    of the riverine Sr input and significantly higher than the input through

    atmospheric dust deposition. Therefore SGD should be considered as an

    important continental source of Sr to the basin.

  • 25.
    Winton, V.H.L.
    et al.
    Curtin University, Perth.
    Dunbar, G.B.
    Antarctic Research Centre, Wellington.
    Atkins, C.B.
    Victoria University, Wellington.
    Bertler, N.A.N.
    Antarctic Research Centre, Wellington.
    Delmonte, Barbara
    University of Milano-Bicocca, Milano.
    Andersson, Per
    Swedish Museum of Natural History, Department of Geology.
    Bowie, A
    University of Tasmania, Hobart.
    Edwards, R.
    Curtin University, Perth.
    The origin of lithogenic sediment in the south-western Ross Sea and implications for iron fertilization2016In: Antarctic Science, ISSN 0954-1020, E-ISSN 1365-2079, Vol. 28, no 4, p. 250-260Article in journal (Refereed)
    Abstract [en]

    Summer iron (Fe) fertilization in the Ross Sea has previously been observed in association with diatom productivity, lithogenic particles and excess Fe in the water column. This productivity event occurred during an early breakout of sea ice via katabatic winds, suggesting that aeolian dust could be an important source of lithogenic Fe required for diatom growth in the Ross Sea. Here we investigate the provenance of size-selected dust deposited on sea ice in McMurdo Sound, south-western (SW) Ross Sea. The isotopic signature of McMurdo Sound dust (0.70533< 87Sr/86Sr< 0.70915 and -1.1 < εNd(0) <3.45)confirms that dust is locally sourced from the McMurdo Sound debris bands and comprises a two-component mixture of McMurdo Volcanic Group and southern Victoria Land lithologies. In addition, the provenance of lithogenic sediment trapped in the water column was investigated, and the isotopic signature (εNd(0) =3.9, 87Sr/86Sr = 0.70434) is differentiated from long-range transported dust originating from South America and Australia. Elevated lithogenic accumulation rates in deeper sediment traps in the Ross Sea suggest that sinking articles in the water column cannot simply result from dust input at the surface. This discrepancy can be best explained by significant upwelling and remobilization of lithogenic Fe from the sea floor.

  • 26.
    Winton, V.H.L.
    et al.
    Swedish Museum of Natural History, Department of Geology. Curtin University Perth Australia.
    Dunbar, G.B.
    University of Wellington, New Zealand.
    Bertler, N.A.N.
    University of Wellington, New Zealand.
    Millet, M.-A
    University of Wellington, New Zealand.
    Delmonte, B
    University of Milano-Bicocca, Milano Italy.
    Atkins, C.B.
    Durham University, Durham UK.
    Chewings, J.M.
    University of Wellington, New Zealand.
    Andersson, Per
    Swedish Museum of Natural History, Department of Geology.
    The contribution of aeolian sand and dust to iron fertilization of phytoplankton blooms in southwestern Ross Sea, Antarctica2014In: Global Biogeochemical Cycles, ISSN 0886-6236, E-ISSN 1944-9224Article in journal (Refereed)
  • 27.
    Winton, V.H.L.
    et al.
    Curtin University.
    Edwards, R
    Curtin University.
    Delmonte, B
    University of Milano-Bicocca.
    Ellis, A
    Curtin University.
    Andersson, Per
    Swedish Museum of Natural History, Department of Geology.
    Bowie, A
    University of Tasmania.
    Bertler, N.A.N.
    University of Wellington.
    Neff, P.
    University of Rochester.
    Tuohy, A
    University of Wellington.
    Multiple sources of soluble atmospheric iron to Antarctic waters2016In: Global Biogeochemical Cycles, ISSN 0886-6236, E-ISSN 1944-9224, Vol. 30, no 3, p. 421-437Article in journal (Refereed)
    Abstract [en]

    The Ross Sea, Antarctica, is a highly productive region of the Southern Ocean. Significant new sources of iron (Fe) are required to sustain phytoplankton blooms in the austral summer. Atmospheric deposition is one potential source. The fractional solubility of Fe is an important variable determining Fe availability for biological uptake. To constrain aerosol Fe inputs to the Ross Sea region, fractional solubility of Fe was analyzed in a snow pit from Roosevelt Island, eastern Ross Sea. In addition, aluminum, dust, and refractory black carbon (rBC) concentrations were analyzed, to determine the contribution of mineral dust and combustion sources to the supply of aerosol Fe. We estimate exceptionally high dissolved Fe (dFe) flux of 1.2 × 10−6 g m−2 y−1 and total dissolvable Fe flux of 140 × 10−6 g m−2 y−1 for 2011/2012. Deposition of dust, Fe, Al, and rBC occurs primarily during spring-summer. The observed background fractional Fe solubility of ~0.7% is consistent with a mineral dust source. Radiogenic isotopic ratios and particle size distribution of dust indicates that the site is influenced by local and remote sources. In 2011/2012 summer, relatively high dFe concentrations paralleled both mineral dust and rBC deposition. Around half of the annual aerosol Fe deposition occurred in the austral summer phytoplankton growth season; however, the fractional Fe solubility was low. Our results suggest that the seasonality of dFe deposition can vary and should be considered on longer glacial-interglacial timescales.

  • 28.
    Winton, V.H.L.
    et al.
    Curtin University Perth Australia.
    Edwards, R.
    Curtin University Perth Australia.
    Delmonte, B.
    University of Milano-Bicocca, Milan, Italy.
    Ellis, A
    Curtin University, Perth, Australia.
    Andersson, Per
    Swedish Museum of Natural History, Department of Geology.
    Bowie, A
    University of Tasmania, Hobart, Australia.
    Bertler, N.A.N.
    University of Wellington, Wellington, New Zealand.
    Neff, P.
    University of Rochester, Rochester, New York.
    Tuohy, A.
    University of Wellington, Wellington, New Zealand.
    Multiple sources of soluble atmospheric iron to Antarctic waters2016In: Global Biogeochemical Cycles, ISSN 0886-6236, E-ISSN 1944-9224Article in journal (Refereed)
  • 29.
    Wortberg, Katharina
    et al.
    Luleå Technical University.
    Conrad, Sarah
    Luleå Technical University.
    Andersson, Per
    Swedish Museum of Natural History, Department of Geology.
    Ingri, Johan
    Luleå Technical University.
    Strontium Isotopes - A Tracer for River Suspended Iron Aggregates2017In: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 95, p. 85-90Article in journal (Refereed)
    Abstract [en]

    The Kalix River shows distinct temporal variations in the Sr-isotope ratio in filtered water (0.726 to 0.732). During base flow in winter the 87Sr/86Sr ratio is on average 0.730. When discharge increases and peaks during spring flood the 87Sr/86Sr ratio shows the most radiogenic (0.732) values. The temporal variations in the 87Sr/86Sr ratio in the Kalix River can be explained by mixing of water from the woodlands and the mountain areas.

    During high water discharge in May the 87Sr/86Sr ratios are more radiogenic in the suspended phase (1 kDa - 70 µm) compared to the truly dissolved phase (<1 kDa). The difference in 87Sr/86Sr ratio between the two phases (Δ 87Sr/86Sr) is linearly correlated with the suspended iron concentration. During spring flood Sr and Fe derived from an additional source, reach the river. Deep groundwater has a more radiogenic 87Sr/86Sr isotope ratio than the Kalix River during spring flood and thus, represents a possible source for the suspended Fe and the associated Sr. Strontium can be coprecipitated with and adsorbed to different types of Fe aggregates. We propose that the Sr-isotope ratio in the suspended phase reflects the isotopic composition of the water at the interface between anoxic groundwater and oxic stream water in the riparian zone, where the Fe aggregates are formed. These particles dominate the suspended phase in the river and the mixing with mountain waters, poor in Fe, produces the difference in the isotopic signature. The different signatures in suspended and truly dissolved fraction indicate that these aggregates are relatively stable during stream-river transport. As such the 87Sr/86Sr can be used to trace the origin of the non-detrital suspended phase.

1 - 29 of 29
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