Lignin's ability to nucleate ice via immersion freezing and its stability towards physicochemical treatments and atmospheric processing

doi:10.5194/acp-2020-589

GSTDTAP > 地球科学

DOI	10.5194/acp-2020-589
	Lignin's ability to nucleate ice via immersion freezing and its stability towards physicochemical treatments and atmospheric processing
	Sophie Bogler and Nadine Borduas-Dedekind
	2020-06-25
发表期刊	Atmospheric Chemistry and Physics
出版年	2020
英文摘要	Aerosol–cloud interactions dominate the uncertainties in current predictions of the atmosphere's radiative balance. Specifically, the ice phase remains difficult to predict in mixed-phase clouds, where liquid water and ice coexist. The formation of ice in these clouds originates from heterogeneous ice nucleation processes, of which immersion freezing is a dominant pathway. Among atmospheric surfaces capable of templating ice, mineral dust, biological material, and more recently organic matter are known to initiate freezing. To further our understanding of the role of organic matter in ice nucleation, we chose to investigate the ice nucleation (IN) ability of a specific sub-component of atmospheric organic matter, the biopolymer lignin. Ice nucleation experiments were conducted in our home-built Freezing Ice Nuclei Counter (FINC) to measure freezing temperatures in the immersion freezing mode. We find that lignin acts as an ice active macromolecule at temperatures relevant for mixed-phase cloud processes (e.g. 50 % activated fraction up to −18.8 °C at 200 mg C L⁻¹). Within a dilution series of lignin solutions, we observed a non-linear effect in freezing temperatures; the number of IN sites per mg carbon increased with decreasing lignin concentration. We attribute this change to a concentration-dependant aggregation of lignin in solution. We further investigated the effect of physicochemical treatments on lignin's IN activity, including experiments with sonication, heating and reaction with hydrogen peroxide. Indeed, harsh conditions such as heating to 260 °C and addition of 1 : 750 g of lignin to mL of hydrogen peroxide were needed to decrease lignin's IN activity to the instrument's background level. Next, photochemistry and ozonation experiments were conducted to test the effect of atmospheric processing on lignin's IN activity. We showed that this activity was not susceptible to changes under atmospherically relevant conditions, despite chemical changes observed by UV/Vis absorbance. Our results present lignin as a recalcitrant IN active subcomponent of organic matter within for example biomass burning aerosols and brown carbon, and contribute to the understanding of how soluble organic material in the atmosphere can nucleate ice.
领域	地球科学
URL	查看原文
引用统计
文献类型	期刊论文
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/278062
专题	地球科学
推荐引用方式 GB/T 7714	Sophie Bogler and Nadine Borduas-Dedekind. Lignin's ability to nucleate ice via immersion freezing and its stability towards physicochemical treatments and atmospheric processing[J]. Atmospheric Chemistry and Physics,2020.
APA	Sophie Bogler and Nadine Borduas-Dedekind.(2020).Lignin's ability to nucleate ice via immersion freezing and its stability towards physicochemical treatments and atmospheric processing.Atmospheric Chemistry and Physics.
MLA	Sophie Bogler and Nadine Borduas-Dedekind."Lignin's ability to nucleate ice via immersion freezing and its stability towards physicochemical treatments and atmospheric processing".Atmospheric Chemistry and Physics (2020).