Significant broadband extinction abilities of bioaerosols

Abstract

Bioaerosol, an important constituent of the atmosphere, can directly affect light radiation characteristics due to absorption and scattering effects. Current research lacks a reasonable explanation for the extinction abilities of bioaerosols in a broadband. Herein, we measured the reflectance spectra of 12 common biomaterials and calculated their complex refractive indexes. The peaks of the imaginary part of the complex refractive indexes are located at wavelengths of approximately 0.7, 2.7, 6.1 and 9.5 μm. Based on photographs of the floating structures of bioaerosols, we constructed a model for calculating the extinction abilities of bioaerosols in the wavelength range of 240 nm to 14 μm. Taking AN02 spores as an example, absorption was found to account for more than 90% of the total extinction. In addition, the theoretical calculations and experimental data of transmittance corresponding to the smoke box show that bioaerosol exhibits significant broadband extinction ability from UV to IR bands, which provides new directions for the development of broadband light attenuation materials.

The effect of biological particles and their ageing processes on aerosol radiative properties: Model sensitivity studies

“…Arakawa et al (2003) reported 1.5 ≤ nBAP ≤ 1.56 and 3 • 10 -5 ≤ kBAP ≤ 6 • 10 -4 for bacteria (Erwinia herbicola) in the wavelength range of 0.3-2.5 µm. Other groups found a broader range of n and k (Table 1) for different types of BAPs and irradiation wavelengths (Hu et al, 2019;Thrush et al, 2010). The 175 imaginary part can vary by three orders of magnitude for different BAP types (Hu et al, 2019).…”

“…Other groups found a broader range of n and k (Table 1) for different types of BAPs and irradiation wavelengths (Hu et al, 2019;Thrush et al, 2010). The 175 imaginary part can vary by three orders of magnitude for different BAP types (Hu et al, 2019). Hill et al (2015) showed that the refractive index of BAPs can be estimated based on the chemical composition.…”

“…While their aerosol direct effect is likely globally small due to low BAP number concentration (Löndahl et al, 2014), it may be of greater interest locally and for specific wavelength ranges due to the large size of BAPs (Myhre et al, 2013). The optical properties of BAPs (Arakawa et al, 2003;Hu et al, 2019;Thrush et al, 2010) resemble those of other organic particles as BAPs are largely composed of proteins and other macromolecules. Accordingly, BAPs' optical properties can be ascribed to specific 60 organic functional entities such as amino groups or aromatic structures (Hill et al, 2015;Hu et al, 2019).…”

Study of infrared optical properties of polydisperse aggregated bioparticles based on optimized BCCA model

“…Currently, many researchers have found that factors such as material composition, structure, and monomer size affect the optical properties of aggregates [4] . Hu et al [5] calculated the complex refractive indices of 12 biomaterials and modeled the extinction properties of bioaerosols in the 0.24~14μm wavelength range. Theoretical and experimental results showed that the bioaerosols exhibited significant extinction ability in the UV to IR band.…”

Optimized shape and structure of artificial bioparticles to enhance the optical extinction properties

“…Our group has studied these biomaterials. Hu et al 34 constructed a calculation model for the wideband extinction ability of bioaerosols. Through theoretical calculations and experiments, they verified that bioaerosols have significant extinction capabilities in the ultraviolet to infrared wavelength range.…”