Mexican agricultural soil dust as a source of ice nucleating particles

Abstract

Abstract. Agricultural soil erosion, both mechanical and eolic, may impact cloud processes, as some aerosol particles are able to facilitate ice crystal formation. Given the large agricultural sector in Mexico, this study investigates the ice nucleating abilities of agricultural dust collected at different sites and generated in the laboratory. The immersion freezing mechanism of ice nucleation was simulated in the laboratory via the Universidad Nacional Autónoma de México (UNAM) microorifice uniform deposit impactor (MOUDI) droplet freezing technique (DFT), i.e., UNAM-MOUDI-DFT. The results show that agricultural dust from the Mexican territory promote ice formation in the temperature range from −11.8 to −34.5 ∘C, with ice nucleating particle (INP) concentrations between 0.11 and 41.8 L−1. Furthermore, aerosol samples generated in the laboratory are more efficient than those collected in the field, with T50 values (i.e., the temperature at which 50 % of the droplets freeze) higher by more than 2.9 ∘C. Mineralogical analysis indicated a high concentration of feldspars, i.e., K-feldspar and plagioclase (>40 %), in most of the aerosol and soil samples, with K-feldspar significantly correlated with the T50 of particles with aerodynamic diameters between 1.8 and 3.2 µm. Similarly, the organic carbon (OC) was correlated with the ice nucleation efficiency of aerosol samples from 3.2 to 5.6 and from 1.0 to 1.8 µm. Finally, a decrease in INP efficiency after heating the samples at 300 ∘C for 2 h indicates that the organic matter from agricultural soils plays a predominant role in the ice nucleating abilities of this type of aerosol sample.

Clothing Textiles as Carriers of Biological Ice Nucleation Active Particles

“…For comparison, atmospheric microfibers may reach concentrations of 0.96–13.2 (size: 10–25 μm) ng m –3 and 0.15–2.06 (size: 2000–2500 μm) ng m –3 on average, respectively, at the higher altitudes of the planetary boundary layer . In the troposphere, small fibers are more prevalent and estimated to range between 0.27 and 3.67 ng m –3 , as larger fibers are unlikely transported over larger distances. ,− We propose that CTs transport a new and previously unaccounted source of biological fragments with ice-nucleating properties that merit consideration in cloud modeling approaches. Although caution is advised when extrapolating laboratory findings to larger systems, biologically stained microfibers are expected to be widely dispersed and abundant in the atmosphere − with possible impacts on cloud ice, cloud droplets, and precipitation.…”

Anthropogenic Dust as a Significant Source of Ice‐Nucleating Particles in the Urban Environment

“…Soil dust particles serve as INPs in a wide temperature range of −35° to −6°C (Hill et al., 2016; O'Sullivan et al., 2014; Pereira et al., 2022; Steinke et al., 2016; Tobo et al., 2014). Their ice nucleation activities are influenced by the composition, particularly the presence of the mixture of dust with biological compounds (Conen et al., 2011) and organic matters (OM) (Pereira et al., 2022; Tobo et al., 2014). Compared to ground‐based soil dust, limited attention has been given to the ice nucleation activity of airborne soil dust originating from disturbed soils.…”

“…Despite the high mass loading of anthropogenic dust in the urban atmosphere (5∼200 Tg.year 1 reported by Xia et al (2022)) and its direct and indirect effects on the urban climate (Philip et al, 2017;Xia et al, 2021), limited studies have investigated the ice nucleation properties of this dust species compared to other pollutants. Soil dust particles serve as INPs in a wide temperature range of 35°to 6°C (Hill et al, 2016;O'Sullivan et al, 2014;Pereira et al, 2022;Steinke et al, 2016;Tobo et al, 2014). Their ice nucleation activities are influenced by the composition, particularly the presence of the mixture of dust with biological compounds (Conen et al, 2011) and organic matters (OM) (Pereira et al, 2022;Tobo et al, 2014).…”