Publication

Article Metrics

Citations


Online attention

Distinct chemical and mineralogical composition of Icelandic dust compared to northern African and Asian dust

DOI: 10.5194/acp-20-13521-2020 DOI Help

Authors: Clarissa Baldo (University of Birmingham) , Paola Formenti (LISA, UMR CNRS 7583, Université Paris-Est Créteil, Université de Paris, Institut Pierre-Simon Laplace (IPSL)) , Sophie Nowak (Plateforme RX - UFR de Chimie, Université de Paris) , Servanne Chevaillier (LISA, UMR CNRS 7583, Université Paris-Est Créteil, Université de Paris, Institut Pierre-Simon Laplace (IPSL)) , Mathieu Cazaunau (LISA, UMR CNRS 7583, Université Paris-Est Créteil, Université de Paris, Institut Pierre-Simon Laplace (IPSL)) , Edouard Pangui (LISA, UMR CNRS 7583, Université Paris-Est Créteil, Université de Paris, Institut Pierre-Simon Laplace (IPSL)) , Claudia Di Biagio (LISA, UMR CNRS 7583, Université Paris-Est Créteil, Université de Paris, Institut Pierre-Simon Laplace (IPSL)) , Jean-francois Doussin (0000-0001-8273-6211) , Konstantin Ignatyev (Diamond Light Source) , Pavla Dagsson-waldhauserova (Agricultural University of Iceland; Czech University of Life Sciences Prague) , Olafur Arnalds (Agricultural University of Iceland) , A. Robert Mackenzie (University of Birmingham) , Zongbo Shi (University of Birmingham)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Atmospheric Chemistry And Physics , VOL 20 , PAGES 13521 - 13539

State: Published (Approved)
Published: November 2020
Diamond Proposal Number(s): 22244 , 12760 , 10327

Open Access Open Access

Abstract: Iceland is a highly active source of natural dust. Icelandic dust has the potential to directly affect the climate via dust–radiation interaction and indirectly via dust–cloud interaction, the snow/ice albedo effect and impacts on biogeochemical cycles. The impacts of Icelandic dust depend on its mineralogical and chemical composition. However, a lack of data has prevented an accurate assessment of the role of Icelandic dust in the Earth system. Here, we collected surface sediment samples from five major Icelandic dust hotspots. Dust aerosols were generated and suspended in atmospheric chambers, and PM10 and PM20 fractions were collected for further analysis. We found that the dust samples primarily consist of amorphous basaltic materials ranging from 8 wt % (from the Hagavatn hotspot) to 60 wt %–90 wt % (other hotspots). Samples had relatively high total Fe content (10 wt %–13 wt %). Sequential extraction of Fe to determine its chemical form shows that dithionite Fe (Fe oxides such as hematite and goethite) and ascorbate Fe (amorphous Fe) contribute respectively 1 %–6 % and 0.3 %–1.4 % to the total Fe in Icelandic dust. The magnetite fraction is 7 %–15 % of total Fe and 1 %–2 wt % of PM10, which is orders of magnitude higher than in mineral dust from northern Africa. Nevertheless, about 80 %–90% of the Fe is contained in pyroxene and amorphous glass. The initial Fe solubility (ammonium acetate extraction at pH 4.7) is from 0.08 % to 0.6 %, which is comparable to low-latitude dust such as that from northern Africa. The Fe solubility at low pH (i.e. pH 2) is significantly higher than typical low-latitude dust (up to 30 % at pH 2 after 72 h). Our results revealed the fundamental differences in composition and mineralogy of Icelandic dust from low-latitude dust. We attribute these differences to the low degree of chemical weathering, the basaltic composition of the parent sediments and glacial processes. Icelandic dust contributes to the atmospheric deposition of soluble Fe and can impact primary productivity in the North Atlantic Ocean. The distinct chemical and mineralogical composition, particularly the high magnetite content (1 wt %–2 wt %), indicates a potentially significant impact of Icelandic dust on the radiation balance in the subpolar and polar regions.

Subject Areas: Earth Science, Chemistry


Instruments: I18-Microfocus Spectroscopy

Documents:
acp-20-13521-2020.pdf