Nanok Expedition &
Université Libre de Bruxelles

The ULB wants to study the dust contribution to algae growth and extension on the Greenland Ice Sheet and its accelerated melting by collecting snow and cryoconite samples. Furthermore, scientists will assess the impact of microplastics on remote seawater along the Greenland east coast.

Both of these experiments will be run in collaboration with G-Time Laboratory & B-GeoSys.

Dust & algae on the Greenland ice sheet

Introduction

Over the last 25 years, the melting of Greenland Ice Sheet (GIS) has accelerated dramatically and is now in line with the worst-case scenario predicted by the Intergovernmental Panel on Climate Change (IPCC). One the cause of this worrying melting is the proliferation of algae that darkens the surface of the ice, hence decreasing the albedo of the ice and ultimately facilitating the melting. These algal blooms are widespread on the south-west of the GIS (i.e., “Dark Zone”) where they are fuelled by atmospheric dust deposition and in particular by the phosphorus that it contains. Here we propose to collect snow samples along the 600 km traverse to filtrate and analyse dust for their chemical composition (major and trace elements). Cryoconite (Figure) will be also collected to study their origin and grain-size effect compared to the dust. A better knowledge of the geochemical fingerprint of dust will allow (i) to trace the geographical provenance of the dust and (ii) determine the mineral phosphorus (and other potential micronutrients, such as iron) content and thus evaluate their potential to sustain microbial growth.

Method used

2L of surface snow (top 10 cm) will be collected regularly of the traverse in pre-cleaned bottle. Once collected, samples should be maintained at freezing temperature. Melting of snow, filtration and collection of dust, dissolution will be performed in clean rooms to avoid any contamination at ULB. Further analysis will involve the determination of chemical composition (Rare Earth Elements (REE) and major element concentrations on ICP-MS) as well as mineralogy (qXRD, electron microscopy) performed at ULB (G-Time and B-GeoSys) and partners at GFZ German Research Center for Geosciences in Potsdam.

Expected results

Dust deposition is key to algal growth on ice. The determination of the provenance of dust source and their phosphorus content, and other potential trace elements playing the role of micronutrients, will give us a first-hand estimate on whether the zone of annual algal growth (Dark Zone) can extend further east on the GIS. It will also shed light on the dust characteristics required for boosting the algae growth.

References

J. McCutcheon, S. Lutz, C. Williamson, J. M Cook, A. J Tedstone, A. Vanderstraeten, S. A Wilson, A. Stockdale, S. Bonneville, A. M Anesio, M. L Yallop, J. B McQuaid, M. Tranter, L. G Benning Mineral phosphorus drives glacier algal blooms on the Greenland Ice Sheet. Nature Communications 12, 570 (2021). https://doi.org/10.1038/s41467-020-20627-w.
Vanderstraeten, A., Bonneville, S., Gili, S., De Jong, J., Debouge, W., Claeys, P., & Mattielli, N. (2020). First Multi-Isotopic (Pb-Nd-Sr-Zn-Cu-Fe) Characterisation of Dust Reference Materials (ATD and BCR-723): A Multi-Column Chromatographic MethodOptimised to Trace Mineral and Anthropogenic Dust Sources. Geostandards andgeoanalytical research, 44(2), 307-329. doi:10.1111/ggr.12320
Le Roux, G., Fagel, N., De Vleeschouwer, F., Krachler, M., Debaille, V., Stille, P., Mattielli, N., Van der Knaap, W., Van Leeuwen, J. F., & Shotyk, W. (2012). Volcano- and climate-driven changes in atmospheric dust sources and fluxes since the Late Glacial in Central Europe. Geology, 40, 335-338. doi:10.1130/G32586.1

Microplastic in remote sea water

Introduction

The widespread microplastic (< 5 mm) pollution in the aquatic environment is one of the major challenges of the 21st century. The flux of microplastic to the sea is projected to increase by an order of magnitude by 2030. This flux is likely to have damaging effect on the aquatic wildlife but also to disturb the carbon cycle from to top surface all the way down to the benthic environments (sediment) which are their ultimate repository. So far, there has been very studies on the extend of microplastic pollution on the Eastern coast of Greenland and their fjords. For the Nanok expedition, we propose to collect microplastic using trawling net during the Kayak traverse on the East coast of Greenland. The microplastic will be characterized for their abundance, size and the polymer identities before being used as substrate in laboratory experiments to measure their degradation kinetics under simulated-benthic conditions.

Method used

A conical trawling net fitted with a 50-mL particle collector will be deployed regularly on the back of the kayak during the traverse on the East coast of Greenland. The trawling device will be equipped with flowmeter to measure the quantity of water entering the net. After each deployment, the net will be rinsed and all particles will be concentrated into the 50 mL tube that will be stored for later use. Polymer identification will be analysed by vibrational microspectroscopy techniques (i.e., µRaman and µFTIR) and grain size will be analysed by laser-diffraction particle sizing (Malvern Mastersizer).

Expected results

This campaign will provide the first systematic survey of microplastic pollution on the coastal and fjord waters of South-East Greenland. It will also provide ULB partners with the much-needed, naturally-treated microplastic materials necessary to perform degradation experiments in simulated-benthic conditions.

References

Ross, P.S., Chastain, S., Vassilenko, E. et al. Pervasive distribution of polyester fibres in the Arctic Ocean is driven by Atlantic inputs. Nature Communications 12, 106 (2021). https://doi.org/10.1038/s41467-020-20347-1