Тип публикации: статья из журнала

Год издания: 2017

Идентификатор DOI: 10.1016/j.gca.2017.07.012

Ключевые слова: Arctic reactivity, iron particles, Transmission Electron Microscopy, X-ray Absorption Spectroscopy

Аннотация: Rivers are significant contributors of Fe to the ocean. 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, mineralogyПоказать полностью, 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 from the main channel and tributaries representing watersheds that span a wide range in topography and lithology were taken after the spring flood in June 2013 and summer baseflow in July 2012. Fe-bearing particles were identified, using Transmission Electron Microscopy, as large (200 nm–1 µm) aggregates of smaller (20–30 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-ray microscopy (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. © 2017 Elsevier Ltd

Журнал: Geochimica et Cosmochimica Acta

Выпуск журнала: Vol. 213

Номера страниц: 553-573

ISSN журнала: 00167037

Издатель: Elsevier Ltd

• Hirst C. (Department of Geosciences, Swedish Museum of Natural History, Stockholm, Sweden, Department of Geological Sciences, Stockholm University, Stockholm, Sweden, Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden)
• Andersson P.S. (Department of Geosciences, Swedish Museum of Natural History, Stockholm, Sweden)
• Shaw S. (School of Earth and Environmental Sciences, University of Manchester, Manchester, United Kingdom)
• Burke I.T. (School of Earth and Environment, University of Leeds, Leeds, United Kingdom)
• Kutscher L. (Department of Geosciences, Swedish Museum of Natural History, Stockholm, Sweden, Department of Geological Sciences, Stockholm University, Stockholm, Sweden, Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden)
• Murphy M.J. (Department of Earth Sciences, Oxford University, Oxford, United Kingdom)
• Maximov T. (Institute for Biological Problems of the Cryolithozone, Siberian Branch of the Russian Academy of Sciences, Russian Federation, Institute for Natural Sciences, North-Eastern Federal University, Yakutsk, Russian Federation)
• Pokrovsky O.S. (Georesources and Environment Toulouse, GET, UMR5563 CNRS, University of Toulouse, France, N. Laverov Federal Center for Integrated Arctic Research, Arkhangelsk, Russian Federation)
• Mörth C.-M. (Department of Geological Sciences, Stockholm University, Stockholm, Sweden, Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden)
• Porcelli D. (Department of Earth Sciences, Oxford University, Oxford, United Kingdom)

• Scopus