SEGH Articles

Dust Deposition in snow from NorthEast Antarctica: mineralogical, morphological and chemical characterization

05 October 2014
Aubry Vanderstraeten is a PhD student and won the runner-up prize for best student poster at SEGH 2014.


Mineral dusts are a major source of micronutrients (e.g. Fe) that limit phytoplankton growth in the open ocean, in particular in the so-called “High Nutrient Low Chlorophyll” (HNLC) oceanic zones. The southern Ocean is by far the largest of all HNLC regions and thus has the potential to greatly enhance the biological CO2 pump at the global scale. As the aerosol fluxes and sources in the southern Ocean are not well constrained and the potential impact of anthropogenic airborne particles may be larger than expected, a multidisciplinary study is being carried out on dust-bearing snow samples collected in NE Antarctica. Our goals are multiple: (i) determine the mineralogy, morphology and chemical composition of these dusts and, (ii) quantify, by using heavy stable isotopic signatures, the origin and the relative contribution of desert-derived, volcanic and anthropogenic particles in the dust, (iii) estimate the bioavailable fraction of bio-essential elements such as Fe through chemical extraction.

Snow samples were collected at four sites: two a few kilometres from the sea, at the summit of the Derwael Ice Rise (about 200km North of the Belgian Princess Elisabeth Station) and two other locations in a continental area (~225km inland) around the Princess Elisabeth station in the Sør Rondane Mountains. Three litres of snow from each site were melted and filtrated on 0.2 µm poresize NucleporeÓ polycarbonate filters in an ISO 5-class clean room. Subsequently, a series of single particle analyses were performed by (i) FEG-SEM (Field Emission Gun-Scanning Electron Microscopy) to determine particles-size distribution of dust; (ii) automated-SEM-EDS (Energy Dispersive Spectroscopy) to estimate the chemical composition of individual dust particles; (iii) TEM-SAED analysis (Transmission Electron Microscopy Selected Area Electron Diffraction) to identify the minerals present. In addition, trace element compositions of the bulk samples were analyzed by high-resolution ICP-MS.

Preliminary data in elemental composition and mineralogy indicate similarities between dust samples and the rock-forming minerals from the Sør Rondane Mountains suggesting a local dust source. However, major distinctions can be made between coastal and inland dust samples: (i) mineralogical distributions are very distinct; (ii) a large proportion of the quartz and feldspath dust particles exhibit surprisingly enrichment in iron (less than 20% of particles for inland samples and up to 80% for coastal samples), which is probably due to surface Fe-rich coating/aggregates; (iii) coastal samples are heavily enriched (vs. upper continental crust reference values) in Pb and Ni. These Fe, Pb and Ni enrichment trends tend to suggest an external and distal source of dust at the coast, potentially impacted by anthropogenic activities.

To complement those preliminary results, new sampling campaign will take place in December 2014 at the same locations to acquire large quantity of snow. In addition, passive dust collectors will be placed for a period of one year along a transect connecting the Sør Rondane Mountains and the Derwael Ice Rise. The perspectives of this new sampling campaign aim to fulfil our analysis plan through isotopic analyses and chemical extractions.

This in-depth characterisation study will improve our knowledge and understanding of dusts reaching the coast of NE-Antarctica, which represent a proxy of the dust materials supplied to the Southern Ocean. 

by Aubry Vanderstraeten, PhD student

Keep up to date

Submit Content

Members can keep in touch with their colleagues through short news and events articles of interest to the SEGH community.

Science in the News

Latest on-line papers from the SEGH journal: Environmental Geochemistry and Health

  • Fate and partitioning of heavy metals in soils from landfill sites in Cape Town, South Africa: a health risk approach to data interpretation 2019-06-14


    The fate and persistence of trace metals in soils and sludge from landfill sites are crucial in determining the hazard posed by landfill, techniques for their restoration and potential reuse purposes of landfill sites after closure and restoration. A modified European Community Bureau of Reference’s (BCR) sequential extraction procedure was applied for partitioning and evaluating the mobility and persistence of trace metals (As, Cd, Cr, Cu, Ni, Pb, Sb, Se, Zn) in soils from three landfill sites and sludge sample from Cape Town, South Africa. Inductively coupled plasma optical emission spectroscopy was used to analyze BCR extracts. The mobility sequence based on the BCR mobile fraction showed that Cu (74–87%), Pb (65–80%), Zn (59–82%) and Cd (55–66%) constituted the mobile metals in the soils from the three sites. The mobility of Cu, Zn and Ni (> 95%) was particularly high in the sludge sample, which showed significant enrichment compared to the soil samples. Geo-accumulation index (Igeo) and risk assessment code were used to further assess the environmental risk of the metals in the soils. Exposure to the soils and sludge did not pose any non-cancer risks to adult and children as the hazard quotient and hazard index values were all below the safe level of 1. The cancer risks from Cd, Cr and Ni require that remedial action be considered during closure and restoration of the landfill sites.

  • An investigation into the use of < 38 µm fraction as a proxy for < 10 µm road dust particles 2019-06-13


    It is well documented that a large portion of urban particulate matters is derived from road dust. Isolating particles of RD which are small enough to be inhaled, however, is a difficult process. In this study, it is shown for the first time that the < 38 µm fraction of road dust particles can be used as a proxy for road dust particles < 10 µm in bioaccessibility studies. This study probed similarities between the < 10 and < 38µm fractions of urban road dust to show that the larger of the two can be used for analysis for which larger sample masses are required, as is the case with in vitro analysis. Road dust, initially segregated to size < 38 µm using sieves, was again size segregated to < 10 µm using water deposition. Both the original < 38 µm and the separated < 10 µm fractions were then subject to single particle analysis by SEM–EDX and bulk analysis by ICP-OES for its elemental composition. Dissolution tests in artificial lysosomal fluid, representative of lung fluid, were carried out on both samples to determine % bioaccessibility of selected potentially harmful elements and thus probe similarities/differences in in vitro behaviour between the two fractions. The separation technique achieved 94.3% of particles < 10 µm in terms of number of particles (the original sample contained 90.4% as determined by SEM–EDX). Acid-soluble metal concentration results indicated differences between the samples. However, when manipulated to negate the input of Si, SEM–EDX data showed general similarities in metal concentrations. Dissolution testing results indicated similar behaviour between the two samples in a simulated biological fluid.

  • Degradation of petroleum hydrocarbons in unsaturated soil and effects on subsequent biodegradation by potassium permanganate 2019-06-13


    To date, the oxidation of petroleum hydrocarbons using permanganate has been investigated rarely. Only a few studies on the remediation of unsaturated soil using permanganate can be found in the literature. This is, to the best of our knowledge, the first study conducted using permanganate pretreatment to degrade petroleum hydrocarbons in unsaturated soil in combination with subsequent bioaugmentation. The pretreatment of diesel-contaminated unsaturated soil with 0.5-pore-volume (5%) potassium permanganate (PP) by solution pouring and foam spraying (with a surfactant) achieved the total petroleum hydrocarbon (TPH) removal efficiencies of 37% and 72.1%, respectively. The PP foam, when coupled with bioaugmentation foam, further degraded the TPH to a final concentration of 438 mg/kg (92.1% total reduction). The experiment was conducted without soil mixing or disturbance. The relatively high TPH removal efficiency achieved by the PP–bioaugmentation serial foam application may be attributed to an increase in soil pH caused by the PP and effective infiltration of the remediation agent by foaming. The applied PP foam increased the pH of the acidic soil, thus enhancing microbial activity. The first-order biodegradation rate after PP oxidation was calculated to be 0.068 d−1. Furthermore, 94% of the group of relatively persistent hydrocarbons (C18–C22) was removed by PP–bioaugmentation, as verified by chromatogram peaks. Some physicochemical parameters related to contaminant removal efficiency were also evaluated. The results reveal that PP can degrade soil TPH and significantly enhance the biodegradation rate in unsaturated diesel-contaminated soil when combined with bioaugmentation foam.