Agricultural harvesting emissions of ice nucleating particles

Abstract

<p><strong>Abstract.</strong> Agricultural activities can modify natural ecosystems and change the nature of the aerosols emitted from those landscapes. The harvesting of crops can loft plant fragments and soil dust into the atmosphere that can travel long distances and interact with clouds far from their sources. In this way harvesting may contribute substantially to ice nucleating particle (INP) concentrations, especially in regions where agriculture makes up a large percentage of land use. However, a full characterization of particles emitted during harvesting has not been reported. This study characterizes immersion mode INPs emitted during harvesting of several crops in the High Plains region of the United States. The Colorado State University Continuous Flow Diffusion Chamber (CFDC) and the Ice Spectrometer (IS) were utilized to measure INP concentrations during active harvesting of four crops in Kansas and Wyoming. Large spikes of INPs were observed during harvesting, with concentrations over 200 L<sup>−1</sup> at −30 °C measured during a wheat harvest. To differentiate between mineral and organic components, a novel heating tube method was employed in real-time upstream of the CFDC to deactivate organic INPs in-situ. The results indicate that harvesting produces a complex mixture of organic, soil dust, and mineral components that varies for different crops. Electron microscopy analysis showed that while mineral components made up a large proportion of INPs, organic components comprised over 40 % of measured INPs for certain crops at warm temperatures. Heating and enzyme post-treatment of aerosol samples collected for IS processing indicated that bacteria, heat-labile, and heat-stable organics contributed to wheat harvest-produced INPs. These results indicate that plant material and organic particles are a significant component of harvest INPs and their impacts on ice formation in clouds and precipitation on a regional scale should be explored.</p>

Characteristics of Ice Nucleating Particles in and Around California Winter Storms

“…Across the entire ACAPEX study, number concentrations of INPs ( n INP ) ranged from near 0 up to a few ~10s L −1 at temperatures from −20 to −30 °C (Figure ), which are typical for ambient n INP values at these temperatures in relatively clean environments (DeMott et al, ). While concentrations as high as 100–1,000 L have been observed in heavily dust impacted environments (Boose et al, ; DeMott et al, ) and 100s L −1 in agricultural areas during harvesting (Suski et al, ), no such high values were observed during this study. There was considerable variability in n INP during each flight, with the range in n INP values during any given flight greater than the range in average n INP across all flights, even in cases where CFDC measurements were only made over a narrow temperature range, illustrated in Figure .…”

“…Filter measurements from the Central Valley on 12 February (not shown) were also very similar to those on 11 February in this region. This increase in n INP at these relatively warmer temperatures is commonly indicative of terrestrial biological INPs (Petters & Wright, ; Suski et al, ) and back trajectory analysis during this time period (Figure b) clearly showed air masses intercepting the terrestrial boundary layer prior to arrival at the Bodega Bay site (red lines). Previous studies have observed an increase in n INP following rain events associated with an increase in such terrestrial biological particle concentrations (Huffman et al, ; Prenni et al, ; Tobo et al, ), suggesting that intense rains have a feedback effect on the production and release of INPs (Morris et al ), as observed here.…”

Spatiotemporal patterns of microbial composition and diversity in precipitation

“…, Suski et al. ). Once aerosolized, some microbes are well suited for survival in atmospheric environments.…”

“…Microbes are aerosolized from all terrestrial and aquatic ecosystems (Wilson et al 2015, Joung et al 2017, including the surfaces of multicellular organisms, e.g., plants (Lindemann et al 1982, Burrows et al 2009a, Despr es et al 2012, and fluxes of bioaerosols are often generated or affected by anthropogenic activities (Taha et al 2006, Suski et al 2018. Once aerosolized, some microbes are well suited for survival in atmospheric environments.…”

Field evaluation of a Portable Fine Particle Concentrator (PFPC) for ice nucleating particle measurements

“…Saarikoski et al 2014) and for INP measurements (e.g. McCluskey et al 2017McCluskey et al , 2018Suski et al 2018;DeMott et al 2017;Boose et al 2016a;Prenni et al 2013;. In particular, a 3-stage concentrator first described in Prenni et al (2013) and and based on the principal of virtual impaction, has been used in several field and lab studies in different environments, including agricultural fields, forest and marine environments.…”