Intercomparison Experiment of Water-Insoluble Carbonaceous Particles in Snow in a High-Mountain Environment (1598 m a.s.l.)

The harmonization of sampling, sample preparation and laboratory analysis methods to detect carbon compounds in snow requires detailed documentation of those methods and their uncertainties. Moreover, intercomparison experiments are needed to reveal differences and quantify the uncertainties further. Here, we document our sampling, filtering, and analysis protocols used in the intercomparison experiment from three laboratories to detect water-insoluble carbon in seasonal surface snow in the high-mountain environment at Kolm Saigurn (47.067842° N, 12.98394° E, alt 1598 m a.s.l.), Austria. The participating laboratories were TU Wien (Austria), the University of Florence (Italy), and the Finnish Meteorological Institute (Finland). For the carbon analysis, the NIOSH5040 and EUSAAR2 protocols of the OCEC thermal-optical method were used. The median of the measured concentrations of total carbon (TC) was 323 ppb, organic carbon (OC) 308 ppb, and elemental carbon (EC) 16 ppb. The methods and protocols used in this experiment did not reveal large differences between the laboratories, and the TC, OC, and EC values of four inter-comparison locations, five meters apart, did not show meter-scale horizontal variability in surface snow. The results suggest that the presented methods are applicable for future research and monitoring of carbonaceous particles in snow. Moreover, a recommendation on the key parameters that an intercomparison experiment participant should be asked for is presented to help future investigations on carbonaceous particles in snow. The work contributes to the harmonization of the methods for measuring the snow chemistry of seasonal snow deposited on the ground

Bestimmung von EC und Mineralstaub in Schnee- und Eisproben

Abweichender Titel nach Übersetzung der Verfasserin/des VerfassersMineral dust (MD) and elemental carbon (EC) deposited on snow surfaces lead to a variety of consequences for the environment. Hence, the determination in snow is of great interest. Thermal-optical analysis (TOA) is routinely used for the determination of EC, while its use for the analysis of carbonate carbon (CC), as possible proxy for MD, is not as common. Within this work the possibility to determine both CC and EC in snow samples within one analytical run is evaluated. Thereby the challenges caused by the optical properties of hematite are considered. During filtration of the liquid sample a slight vacuum has to be applied to avoid leaks. The filter loadings were found to be homogeneous, but a slight enrichment on the outer rim of the filter was observed. Cutting filters and weighing of these aliquots was found to be suitable for partitioning. Adding NH4H2PO4 as coagulant to increase the filter efficiency for EC led to problems regarding the OC / EC split, since the optical correction via the transmittance signal could not be performed. For the removal of CC rinsing of samples with HCl is recommended. Temperature steps attributed to CC were identified by reference substances and real samples containing MD. CC assessed from the thermograms correlated with the calzium concentration, but CC from TOA was higher. A comparison of the change in transmittance due to iron compounds was performed based on reference substances and samples containing defined amounts of MD.13

Micro- and Nanoplastics in Alpine Snow: A New Method for Chemical Identification and (Semi)Quantification in the Nanogram Range

We present a new method for chemical characterization of micro- and nanoplastics based on thermal desorption–proton transfer reaction–mass spectrometry. The detection limit for polystyrene (PS) obtained is <1 ng of the compound present in a sample, which results in 100 times better sensitivity than those of previously reported by other methods. This allows us to use small volumes of samples (1 mL) and to carry out experiments without a preconcentration step. Unique features in the high-resolution mass spectrum of different plastic polymers make this approach suitable for fingerprinting, even when the samples contain mixtures of other organic compounds. Accordingly, we got a positive fingerprint of PS when just 10 ng of the polymer was present within the dissolved organic matter of snow. Multiple types of microplastics (polyethylene terephthalate (PET), polyvinyl chloride, and polypropylene carbonate), were identified in a snowpit from the Austrian Alps; however, only PET was detected in the nanometer range for both snowpit and surface snow samples. This is in accordance with other publications showing that the dominant form of airborne microplastics is PET fibers. The presence of nanoplastics in high-altitude snow indicates airborne transport of plastic pollution with environmental and health consequences yet to be understood