Project Conclusions
- The amount of polycyclic aromatic hydrocarbons (PAHs) and oxygenated PAHs in the particle phase were found to be negligible. Very likely this was due to the very low atmospheric particle number concentration measured at Princess Elisabeth station. Fluorene, phenanthrene, fluoranthene and pyrene were the most ubiquitous PAH compounds found in the samples with concentrations ranging between 1 and over 100 pg/m³. No significant inter-annual differences were found for these compounds.
- 158 samples for the analysis of volatile organic compounds (VOCs) were collected in which around 65 compounds were identified and if possible quantified. This resulted in a dataset of over 10000 data points making it the largest dataset on VOCs and oxygenated VOCs in Antarctica. It can be concluded that oxygenated aromatic compounds are by far the most important group by concentration. Acetophenone, phenol, benzaldehyde and benzoic acid are known oxidation products of primary aromatic compounds and are present in concentrations up to 2 µg/m³. Further, dimethylsulfone (DMSO2), an oxidation product of dimethylsulfide (DMS), clearly showed a decreasing trend in function of the distance of the sample site to the ocean.
- For the first time, carbon isotope ratios of particulate organic carbon (POC) and dissolved organic carbon (DOC) were determined in surface snow samples in the region of PEA. The linear correlation between the DOC-flux and ssNa+-flux indicated that sea spray was the main source of DOC. This was confirmed by the carbon isotopic ratio of the DOC.
- The inorganic chemical analyses showed that the large majority, up to 89 %, of the sampled particles were below 2 μm and up to 50 % of particles are of submicron size. Practically no particles with a size > 5 μm were detected. This particle size pattern showed no significant distinction along the 250 km measurement transect from coast to the plateau, neither when comparing air to surface snow samples.
- For the first time, samples were collected for the analysis on the concentration of ice nucleating particles (INP) for the region of Dronning Maud Land. Compared to studies in other regions of Antarctica, the INP numbers for PEA are at the lower limit. This is an important finding, particularly for modelling studies on the aerosol influence on cloud formation and precipitation.
- The entire sample set presented a comparable mineralogical composition dominated by aluminosilicate, silica and Mg-Fe silicates closely followed by Fe-bearing aluminosilicates and iron or titanium oxides. In a much lesser proportion and non-systematically, metal-bearing particles composed of Cr, Ni, Zn, Cu, Sb, Sn, Tl, Ta were present, indicating anthropogenic sources. Special attention was given to particles containing iron (Fe), as Fe is a key micronutrient, essential for the primary productivity in the austral ocean. The occurrence of Fe-bearing particles was found to be widespread in East Antarctica.
- From chemical and isotopic analyses of particles deposited in surface snow, a novel statistical model based on the found patterns of rare earth elements (REE) has been developed. An additional major potential source area (PSA) for dust particles in East Antarctica could be identified. Besides confirming that Southern South America is the best candidate to explain the dust signature recorded during cold and warm geological periods, this study proposes for warm periods a scheme with also Southern Africa as PSA.
- A climatology of backward air mass trajectories has been established for the first time for the region of East Antarctica around PEA, covering a period of 11 years (2010-2020). A k-means cluster analysis has been performed and four clusters of air mass origin were found. Source regions from South America, Southern Africa and Australia were found to be very limited. The Southern Ocean was a main source region, as was the Antarctic continent itself. For the most important air mass cluster, the source region is mostly restricted to the region above the Antarctic continent and the average altitude along the trajectories in this cluster indicated that this cluster corresponded mainly to air subsiding from the upper troposphere.