Export of ice nucleating particles from a watershed

Abstract

Ice nucleating particles (INP) active at a few degrees below 0°C are produced by a range of organisms and released into the environment. They may affect cloud properties and precipitation when becoming airborne. So far, our knowledge about sources of biological INP is based on grab samples of vegetation, soil or water studied in the laboratory. By combining measurements of INP concentrations in river water with river water discharge rates over the course of 16 months, we obtained a lower limit for the production rate of INP in a watershed covering most of Switzerland (4 × 105 INP−8 m−2 d−1). Coincidentally, we found that INP−8 are likely to retain their potential for catalysing ice formation in the natural environment for at least several months before they are mobilized by an intensive rainfall, washed into the river and exported from the watershed.

Abundance of Biological Ice Nucleating Particles in the Mississippi and Its Major Tributaries

“…In addition, film jet bubble bursting may be more extensive in freshwaters compared to marine due to the increased dissolved organic carbon content. This may be less significant in rivers during low flow rates, as demonstrated for the Rhine in Switzerland [32]. Using single particle aerosol time-of-flight mass spectrometry of aerosols generated from Lake Michigan water, Axson et al [45] found a mass spectral fingerprint dominated by calcium carbonate but also with organic nitrogen markers consistent with the presence of organic material.…”

“…More recently, two studies have measured INPs in river surface waters. Moffett [31] surveyed the river Gwuan from its upper reaches to several kilometres out to sea for total and heat sensitive INP concentrations, while Larsen et al [32] measured INPs weekly at one position in the Rhine, in Basel, Switzerland, over 16 months. Baseline Rhine river concentrations were <100 INPs active at −8 • C mL −1 , but this increased to around 4000 INPs mL −1 at −8 • C during transitory peak flows following intense rainfall, likely associated with the flushing of INPs from plant surfaces, litter, and soil.…”

Soils rich in biological ice-nucleating particles abound in ice-nucleating macromolecules likely produced by fungi

“…Soils could be a relevant source of ice-nucleating particles (INPs) found in the atmosphere, and INPs from soils are also found in precipitation (Creamean et al, 2013(Creamean et al, , 2014 and in rivers (Moffett, 2016;Larsen et al, 2017). Organic matter, or biological residues, associated with soil particles may contribute a major share to atmospheric INPs active at temperatures warmer than −10 • C (Schnell and Vali, 1976;Szyrmer and Zawadzki, 1997;Conen et al, 2011;O'Sullivan et al, 2014;Creamean et al, 2013;Tobo et al, 2014;Hill et al, 2016).…”

“…Trying to identify and count or determine the mass of these fungi in soil could be one approach. However, this approach would not account for the fact that INPs produced by the organisms can be washed off, may be preserved, may accumulate in the soil, and may be exported from a watershed during intense rainfall (Larsen et al, 2017). In a first attempt to gauge the potential relevance of cell-free, ice-nucleating macromolecules likely derived from fungi, we looked for INPs in soils that match the challenge tests described for M. alpina .…”

Revisiting properties and concentrations of ice-nucleating particles in the sea surface microlayer and bulk seawater in the Canadian Arctic during summer

“…E. Irish et al: Revisiting properties and concentrations of ice-nucleating particles in the Canadian Arctic One potential source of INPs to the atmosphere is the ocean. Oceans dominate the Earth's surface, and sea spray generates a large fraction of the aerosol mass in the atmosphere (Lewis and Schwartz, 2004). Several pieces of evidence suggest that the ocean is an important source of INPs to the atmosphere.…”