TC The Cryosphere TC The Cryosphere 1994-0424 Copernicus Publications Göttingen, Germany 10.5194/tc-5-589-2011 Dust from the dark region in the western ablation zone of the Greenland ice sheet Wientjes I. G. M. 1 Van de Wal R. S. W. 1 Reichart G. J. 2 3 Sluijs A. https://orcid.org/0000-0003-2382-0215 4 Oerlemans J. https://orcid.org/0000-0001-5701-4161 1 Institute for Marine and Atmospheric research Utrecht (IMAU), Utrecht University, Princetonplein 5, 3584 CC, Utrecht, The Netherlands Department of Earth Sciences, Utrecht University, Budapestlaan 4, 3584 CD Utrecht, The Netherlands Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570, Bremerhaven, Germany Biomarine Sciences, Institute of Environmental Biology, Utrecht University, Laboratory of Palaeobotany and Palynology, Budapestlaan 4, 3584 CD Utrecht, The Netherlands 22 07 2011 5 3 589 601 Copyright: © 2011 I. G. M. Wientjes et al. 2011 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://tc.copernicus.org/articles/5/589/2011/tc-5-589-2011.html The full text article is available as a PDF file from https://tc.copernicus.org/articles/5/589/2011/tc-5-589-2011.pdf

A dark region tens of kilometres wide is located in the western ablation zone of the Greenland ice sheet. The dark appearance is caused by higher amounts of dust relative to the brighter surroundings. This dust has either been deposited recently or was brought to the surface by melting of outcropping ice. Because the resulting lower albedos may have a significant effect on melt rates, we analysed surface dust on the ice, also called cryoconite, from locations in the dark region as well as locations from the brighter surrounding reference ice with microscopic and geochemical techniques to unravel its composition and origin. We find that (part of) the material is derived from the outcropping ice, and that there is little difference between dust from the dark region and from the reference ice. The dust from the dark region seems enriched in trace and minor elements that are mainly present in the current atmosphere because of anthropogenic activity. This enrichment is probably caused by higher precipitation and lower melt rates in the dark region relative to the ice marginal zone. The rare earth elemental ratios of the investigated material are approximately the same for all sites and resemble Earth's average crust composition. Therefore, the cryoconite probably does not contain volcanic material. The mineralogical composition of the dust excludes Asian deserts, which are often found as provenance for glacial dust in ice cores, as source regions. Consequently, the outcropping dust likely has a more local origin. Finally, we find cyanobacteria and algae in the cryoconite. Total Organic Carbon accounts for up to 5 weight per cent of the cryoconite from the dark region, whereas dust samples from the reference ice contain only 1 % or less. This organic material is likely formed in situ. Because of their high light absorbency, cyanobacteria and the organic material they produce contribute significantly to the low albedo of the dark region.

 European Commission DINOPRO - From Protist to Proxy:Dinoflagellates as signal carriers for climate and carbon cycling during past and present extreme climate transitions (259627) References Basile, I., Grousset, F. E., Revel, M., Petit, J. R., Biscaye, P. E., and Barkov, N. I.: Patagonian origin of glacial dust deposited in {E}ast {A}ntarctica ({V}ostok and {D}ome {C}) during glacial stages 2, 4 and 6, Earth Planet. Sc. Lett., 146, 573–589, 1997. Bøggild, C.&nbsp;E., Oerter, H., and Tukiainen, T.: Increased ablation of {W}isconsin ice in eastern north {G}reenland: observations and modelling, Ann. Glaciol., 23, 144–148, 1996. Bøggild, C.&nbsp;E., Brandt, R.&nbsp;E., Brown, K.&nbsp;J., and Warren, S.&nbsp;G.: The ablation zone in northeast {G}reenland: ice types, albedos and impurities, J. Glaciol., 56, 101–113, 2010. Bullard, J.&nbsp;E. and Austin, M.&nbsp;J.: Dust generation on a proglacial floodplain, {W}est {G}reenland, Aeolian Res., 3, 43–54, 2011. Clausen, H.&nbsp;B., Hammer, C.&nbsp;U., Hvidberg, C.&nbsp;S., Dahl-Jensen, D., Steffensen, J.&nbsp;P., Kipfstuhl, J., and Legrand, M.: A comparison of the volcanic records over the past 4000 years from the {G}reenland {I}ce {C}ore {P}roject and {D}ye 3 {G}reenland ice cores, J. Geophys. Res., 102, 26707–26723, 1997. Fuhrer, K., Wolff, E.&nbsp;W., and Johnsen, S.&nbsp;J.: Timescales for dust variability in the {G}reenland {I}ce {C}ore {P}roject ({G}{R}{I}{P}) ice core in the last 100 000 years, J. Geophys. Res., 104, 31043–31052, 1999. Gajda, R.&nbsp;T.: Cryoconite phenomena on the {G}reenland ice cap in the {T}hule area, Can. Geogr., 3, 35–44, 1958. Greuell, W.: Melt-water accumulation on the surface of the {G}reenland ice sheet: effect on albedo and mass balance, Geogr. Ann. A, 82, 489–498, 2000. Gribbon, P. W.&nbsp;F.: Cryoconite holes on {S}ermikavsak, {W}est {G}reenland, J. Glaciol., 22, 177–181, 1979. Hodson, A., Bøggild, C., Hanna, E., Huybrechts, P., Langford, H., Cameron, K., and Houldsworth, A.: The cryoconite ecosystem on the G}reenland ice sheet, Ann. Glaciol., 51, 123–129, 2010{a. Hodson, A., Cameron, K., Bøggild, C., Irvinne-Fynn, T., Langford, H., Pearce, D., and Banwart, S.: The structure, biological activity and biogeochemistry of cryoconite aggregates upon an Arctic valley glacier: L}ongyearbreen, {S}valbard, J. Glaciol., 56, 349–361, 2010{b. Knap, W.&nbsp;H. and Oerlemans, J.: The surface albedo of the {G}reenland ice sheet: satellite-derived and in situ measurements in the {S}øndre {S}trømfjord area during the 1991 melt season, J. Glaciol., 42, 364–374, 1996. Konzelmann, T., Van&nbsp;de Wal, R. S.&nbsp;W., Greuell, W., Bintanja, R., Henneken, E. A.&nbsp;C., and Abe-Ouchi, A.: Parameterization of global and longwave incoming radiation for the {G}reenland {I}ce {S}heet, Global Planet. Change, 9, 143–164, 1994. Langford, H., Hodson, A., Banwart, S., and Bøggild, C.: The microstructure and biogeochemistry of {A}rctic cryoconite granules, Ann. Glaciol., 51, 87–94, 2010. Maggi, V.: Mineralogy of atmospheric microparticles deposited along the {G}reenland {I}ce {C}ore {P}roject ice core, J. Geophys. Res., 102, 26725–26734, 1997. Mahaney, W.&nbsp;C.: Atlas of sand grain surfae textures and applications, Oxford University Press, Oxford, United Kingdom, 2002. Maurette, M., J{é}hanno, C., Robin, E., and Hammer, C.: Characteristics and mass distribution of extraterrestrial dust from the {G}reenland ice cap, Nature, 328, 699–702, 1987. Mortensen, A.&nbsp;K., Bigler, M., Gr{ö}nvold, K., Steffensen, J.&nbsp;P., and Johnsen, S.&nbsp;J.: Volcanic ash layers from the L}ast {G}lacial {T}ermination in the {N}{G}{R}{I}{P ice core, J. Quaternary Sci., 20, 209–219, 2005. Moune, S., Gauthier, P.&nbsp;J., Gislason, S.&nbsp;R., and Sigmarsson, O.: Trace element degassing and enrichment in the eruptive plume of the 2000 eruption of {H}ekla volcano, {I}celand, Geochim. Cosmochim. Ac., 70, 461–479, 2006. Nieuwenhuize, J., Maas, Y. E.&nbsp;M., and Middelburg, J.&nbsp;J.: Rapid analysis of organic carbon and nitrogen in particulate materials, Mar. Chem., 45, 217–224, 1994. Nordenskj{ö}ld, N.&nbsp;E.: Account of an Expedition to {G}reenland in the year 1870, Geol. Mag., 9, 355–368, 1872. Nriagu, J.&nbsp;O. and Pacyna, J.&nbsp;M.: Quantitative assessment of worldwide contamination of air, water and soils by trace metals, Nature, 333, 134–139, 1988. Oerlemans, J. and Vugts, H.&nbsp;F.: A meteorological experiment in the melting zone of the {G}reenland ice sheet, B. Am. Meteorol. Soc., 74, 355–365, 1993. Petrenko, V.&nbsp;V., Severinghaus, J.&nbsp;P., Brook, E.&nbsp;J., Reeh, N., and Schaefer, H.: Gas records from the {W}est {G}reenland ice margin covering the {L}ast {G}lacial {T}ermination: a horizontal ice core, Quaternary Sci. Rev., 25, 865–875, 2005. Reeh, N., Thomsen, H.&nbsp;H., and Clausen, H.&nbsp;B.: The {G}reenland ice-sheet margin – a mine of ice for paleo-environmental studies, Palaeogeogr. Palaeoclimatol. Palaeocol., 58, 229–234, 1987. Reeh, N., Oerter, H., and Thomsen, H.&nbsp;H.: Comparison between {G}reenland ice-margin and ice-core oxygen-18 records, Ann. Glaciol., 35, 136–144, 2002. Ruth, U., Wagenbach, D., Steffensen, J.&nbsp;P., and Bigler, M.: Continuous record of microparticle concentration and size distribution in the central G}reenland {NGRIP ice core during the last glacial period, J. Geophys. Res., 108, 4098, <a href="http://dx.doi.org/10.1029/2002JD002376">https://doi.org/10.1029/2002JD002376</a>, 2003. Stibal, M., \u{S}aback{á}, M., and Ka\u{s}tovsk{á}, K.: Microbial Communities on Glacier Surfaces in {S}valbard: Impact of physical and chemical properties on abundance and structure of cyanobacteria and algae, Microb. Ecol., 52, 644–654, 2006. Stibal, M., Lawson, E.&nbsp;C., Lis, G.&nbsp;P., Mak, K.&nbsp;M., Wadham, J.&nbsp;L., and Anesio, A.&nbsp;M.: Organic matter content and quality in supraglacial debris across the ablation zone of the {G}reenland ice sheet, Ann. Glaciol., 51, 1–8, 2010. Svensson, A., Biscaye, P.&nbsp;E., and Grousset, F.&nbsp;E.: Characterization of late glacial continental dust in the {G}reenland {I}ce {C}ore {P}roject ice core, J. Geophys. Res., 105, 4637–4656, 2000. Takeuchi, N.: The altitudinal distribution of snow algae on an {A}laska glacier ({G}ulkana {G}lacier in the {A}laska {R}ange), Hydrol. Process., 15, 3447–3459, 2001. Takeuchi, N.: Optical characteristics of cryoconite (surface dust) on glaciers: the relationship between light absorbency and the property of organic matter contained in the cryoconite, Ann. Glaciol., 34, 409–414, 2002. Takeuchi, N.: Temporal and spatial variations in spectral reflectance and characteristics of surface dust on {G}ulkana {G}lacier, {A}laska {R}ange, J. Glaciol., 55, 701–709, 2009. Takeuchi, N., Kohshima, S., and Seko, K.: Structure, formation, and darkening process of albedo reducing material (cryoconite) on a {H}imalayan glacier: a granular algal mat growing on the glacier, Arct. Antarct. Alp. Res., 33, 115–122, 2001. Taylor, S.&nbsp;R. and McLennan, S.&nbsp;M.: The geochemical evolution of the continental crust, Rev. Geophys., 33, 241–265, 1995. Uetake, J., Naganuma, T., Hebsgaard, M.&nbsp;B., Kanda, H., and Kohshima, S.: Communities of algae and cyanobacteria on glaciers in west {G}reenland, Polar Sci., 4, 71–80, 2010. Van de Wal, R. S.&nbsp;W. and Oerlemans, J.: An energy balance model for the {G}reenland ice sheet, Global Planet. Change, 9, 115–131, 1994. Van de Wal, R. S.&nbsp;W., Greuell, W., Van den Broeke, M.&nbsp;R., Reijmer, C.&nbsp;H., and Oerlemans, J.: Surface mass-balance observations and automatic weather station data along a transect near {K}angerlussuaq, {W}est {G}reenland, Ann. Glaciol., 42, 311–316, 2005. Van de Wal, R. S.&nbsp;W., Boot, W., Van den Broeke, M.&nbsp;R., Smeets, C. J. P.&nbsp;P., Reijmer, C.&nbsp;H., Donker, J. J.&nbsp;A., and Oerlemans, J.: Large and rapid melt-induced velocity changes in the ablation zone of the {G}reenland ice sheet, Science, 321, 111–113, 2008. Van den Broeke, M., Smeets, P., Ettema, J., Van der Veen, C., Van de Wal, R., and Oerlemans, J.: Partitioning of melt energy and meltwater fluxes in the ablation zone of the west Greenland ice sheet, The Cryosphere, 2, 179–189, <a href="http://dx.doi.org/10.5194/tc-2-179-2008">https://doi.org/10.5194/tc-2-179-2008</a>, 2008. Wharton, R.&nbsp;A., McKay, C.&nbsp;P., Simmons, G.&nbsp;M., and Parker, B.&nbsp;C.: Cryoconite holes on glaciers, BioScience, 35, 499–503, 1985. Wientjes, I. G. M. and Oerlemans, J.: An explanation for the dark region in the western melt zone of the Greenland ice sheet, The Cryosphere, 4, 261–-268, <a href="http://dx.doi.org/10.5194/tc-4-261-2010">https://doi.org/10.5194/tc-4-261-2010</a>, 2010. Yallop, M.&nbsp;L. and Anesio, A.&nbsp;M.: Benthic diatom flora in supraglacial habitats: a generic-level comparison, Ann. Glaciol., 51, 15–22, 2010. Yde, J.&nbsp;C., Finster, K.&nbsp;W., Raiswell, R., Steffensen, J.&nbsp;P., Heinemeier, J., Olsen, J., Gunnlaugsson, H.&nbsp;P., and Nielsen, O.&nbsp;B.: Basal ice microbiology at the margin of the {G}reenland ice sheet, Ann. Glaciol., 51, 71–79, 2010.