Terrestrial Origin for Abundant Riverine Nanoscale Ice-Nucleating Particles
Environmental Science and Technology
Ice-nucleating particles (INPs) associated with fresh waters are a neglected, but integral component of the water cycle. Abundant INPs were identified from surface waters of both the Maumee River and Lake Erie with ice nucleus spectra spanning a temperature range from -3 to -15 °C. The majority of river INPs were submicron in size and attributed to biogenic macromolecules, inferred from the denaturation of ice-nucleation activity by heat. In a watershed dominated by row-crop agriculture, higher concentrations of INPs were found in river samples compared to lake samples. Further, ice-nucleating temperatures differed between river and lake samples, which indicated different populations of INPs. Seasonal analysis of INPs that were active at warmer temperatures (≥-10 °C; INP -10 ) showed their concentration to correlate with river discharge, suggesting a watershed origin of these INPs. A terrestrial origin for INPs in the Maumee River was further supported by a correspondence between the ice-nucleation signatures of river INPs and INPs derived from the soil fungus Mortierella alpina. Aerosols derived from turbulence features in the river carry INP -10 , although their potential influence on regional weather is unclear. INP -10 contained within aerosols generated from a weir spanning the river, ranged in concentration from 1 to 11 INP m -3 , which represented a fold-change of 3.2 over average INP -10 concentrations sampled from aerosols at control locations.
Knackstedt, Kathryn A.; Moffett, Bruce F.; Hartmann, Susan; Wex, Heike; Hill, Thomas C.J.; Glasgo, Elizabeth D.; Reitz, Laura A.; Augustin-Bauditz, Stefanie; Beall, Benjamin F.N.; Bullerjahn, George S.; Fröhlich-Nowoisky, Janine; Grawe, Sarah; Lubitz, Jasmin; Stratmann, Frank; and McKay, Robert Michael L.. (2018). Terrestrial Origin for Abundant Riverine Nanoscale Ice-Nucleating Particles. Environmental Science and Technology, 52 (21), 12358-12367.