Development of drop freezing ice nucleation chamber (FINC), validation using lignin, and application to organic matter samples

Author(s):  
Anna Miller ◽  
Killian Brennan ◽  
Jörg Wieder ◽  
Claudia Mignani ◽  
Assaf Zipori ◽  
...  

<p>Aerosol-cloud interactions are a source of high uncertainties in predicting future climate. One important aerosol-cloud interaction is ice nucleation of supercooled liquid water droplets caused by ice nucleating particles (INPs). Predicting the distribution and concentration of INPs is a challenge because of their spatial and temporal heterogeneity in source, number, and composition. Organic aerosols are particularly diverse and complex in chemical and physical composition and can be highly ice active to varying degrees. Here we present the development of our drop Freezing Ice Nucleation Chamber (FINC) for the quantification of INP concentration of aerosol in the immersion freezing mode. As part of the development and validation of FINC, we show results from an intercomparison using lignin as a comparison standard with three other drop-freezing instruments (ETH’s Drop Freezing Ice Nucleation counter Zurich (DRINCZ), University of Basel’s LED-based Ice Nucleation Detection Apparatus (LINDA), and Weizmann Institute’s Supercooled Droplet Observation of Microarray (WISDOM)). In addition, we present here preliminary findings of FINC’s application for determining predictors of the ice nucleating ability of organic matter, using several standards and field-collected samples of dissolved organic matter as a proxy for organic aerosol emitted from natural waters. These methods and results can aid in the community’s search for predictors and parameterizations of organic aerosol induced ice nucleation.</p>

2020 ◽  
Author(s):  
Anna J. Miller ◽  
Killian P. Brennan ◽  
Claudia Mignani ◽  
Jörg Wieder ◽  
Robert O. David ◽  
...  

Abstract. Aerosol-cloud interactions, including the ice nucleation of supercooled liquid water droplets caused by ice nucleating particles (INPs) and macromolecules (INMs), are a source of uncertainty in predicting future climate. Because of INPs' and INMs' spatial and temporal heterogeneity in source, number, and composition, predicting their concentration and distribution is a challenge, requiring apt analytical instrumentation. Here, we present the development of our drop Freezing Ice Nucleation Counter (FINC), a droplet freezing technique (DFT), for the quantification of INP and INM concentrations in the immersion freezing mode. FINC's design builds upon previous DFTs and uses an ethanol bath to cool sample aliquots while detecting freezing using a camera. Specifically, FINC uses 288 sample wells of 5–60 μL volume, has a limit of detection of −25.37 ± 0.15 °C with 5 μL, and has an instrument temperature uncertainty of ±0.5 °C. We further conducted freezing control experiments to quantify the non-homogeneous behavior of our developed DFT, including the consideration of eight different sources of contamination. As part of the validation of FINC, an intercomparison campaign was conducted using an NX-illite suspension and an ambient aerosol sample with two other drop-freezing instruments: ETH's DRoplet Ice Nuclei Counter Zurich (DRINCZ) and University of Basel's LED-based ice nucleation detection apparatus (LINDA). We also tabulated an exhaustive list of peer-reviewed DFTs, to which we added our characterized and validated FINC. In addition, we propose herein the use of a water-soluble biopolymer, lignin, as a suitable ice nucleating standard. An ideal INM standard should be inexpensive, accessible, reproducible, unaffected by sample preparation, and consistent across techniques. First, we compare its freezing temperature across different drop-freezing instruments, including on DRINCZ and LINDA, and determine an empirical fit parameter for future drop freezing validations. Second, we show that commercial lignin has a consistent ice nucleating activity across product batches. Third, we demonstrate that the ice nucleating ability of aqueous lignin solutions are stable over time. With these findings, we aim to show that lignin can be used as a good immersion freezing standard in future technique intercomparisons in the field of atmospheric ice nucleation.


2020 ◽  
Author(s):  
Anna J. Miller ◽  
Killian P. Brennan ◽  
Claudia Mignani ◽  
Jörg Wieder ◽  
Assaf Zipori ◽  
...  

Abstract. Aerosol-cloud interactions, including the ice nucleation of supercooled liquid water droplets caused by ice nucleating particles (INPs) and macromolecules (INMs), are a source of uncertainty in predicting future climate. Because of INPs' and INMs' spatial and temporal heterogeneity in source, number, and composition, predicting their concentration and distribution is a challenge, requiring apt analytical instrumentation. Here, we present the development of our drop Freezing Ice Nucleation Counter (FINC), a droplet freezing technique (DFT), for the quantification of INP and INM concentrations in the immersion freezing mode. FINC's design builds upon previous DFTs and uses an ethanol bath to cool sample aliquots while detecting freezing using a camera. Specifically, FINC uses 288 sample wells of 5–60 µL volume, has a limit of detection of −25.37 ± 0.15 ˚C with 5 µL, and has an instrument temperature uncertainty of ± 0.5 ˚C. We further conducted freezing control experiments to quantify the non-homogeneous behavior of our developed DFT, including the consideration of eight different sources of contamination. As part of the validation of FINC, an intercomparison campaign was conducted using an NX-illite suspension and an ambient aerosol sample with two other drop-freezing instruments: ETH's DRoplet Ice Nuclei Counter Zurich (DRINCZ) and University of Basel’s LED-based ice nucleation detection apparatus (LINDA). We also tabulated an exhaustive list of peer-reviewed DFTs, to which we added our characterized and validated FINC. In addition, we propose herein the use of a water-soluble biopolymer, lignin, as a suitable ice nucleating standard. An ideal INM standard should be inexpensive, accessible, reproducible, unaffected by sample preparation, and consistent across techniques. First, we show that commercial lignin has a consistent ice nucleating activity across product batches. Second, we demonstrate that aqueous lignin solutions exhibit good solution stability over time. Third, we compare its freezing temperature across different drop-freezing instruments, including on DRINCZ, LINDA, and on the Weizmann Institute's Supercooled Droplets Observation on a Microarray (WISDOM) and determine an empirical fit parameter for future drop freezing validations. With these findings, we aim to show that lignin can be used as a good immersion freezing standard in future technique intercomparisons in the field of atmospheric ice nucleation.


2021 ◽  
Vol 14 (4) ◽  
pp. 3131-3151
Author(s):  
Anna J. Miller ◽  
Killian P. Brennan ◽  
Claudia Mignani ◽  
Jörg Wieder ◽  
Robert O. David ◽  
...  

Abstract. Aerosol–cloud interactions, including the ice nucleation of supercooled liquid water droplets caused by ice-nucleating particles (INPs) and macromolecules (INMs), are a source of uncertainty in predicting future climate. Because INPs and INMs have spatial and temporal heterogeneity in source, number, and composition, predicting their concentration and distribution is a challenge requiring apt analytical instrumentation. Here, we present the development of our drop Freezing Ice Nuclei Counter (FINC) for the estimation of INP and INM concentrations in the immersion freezing mode. FINC's design builds upon previous droplet freezing techniques (DFTs) and uses an ethanol bath to cool sample aliquots while detecting freezing using a camera. Specifically, FINC uses 288 sample wells of 5–60 µL volume, has a limit of detection of −25.4 ± 0.2 ∘C with 5 µL, and has an instrument temperature uncertainty of ± 0.5 ∘C. We further conducted freezing control experiments to quantify the nonhomogeneous behavior of our developed DFT, including the consideration of eight different sources of contamination. As part of the validation of FINC, an intercomparison campaign was conducted using an NX-illite suspension and an ambient aerosol sample from two other drop freezing instruments: ETH's DRoplet Ice Nuclei Counter Zurich (DRINCZ) and the University of Basel's LED-based Ice Nucleation Detection Apparatus (LINDA). We also tabulated an exhaustive list of peer-reviewed DFTs, to which we added our characterized and validated FINC. In addition, we propose herein the use of a water-soluble biopolymer, lignin, as a suitable ice-nucleating standard. An ideal INM standard should be inexpensive, accessible, reproducible, unaffected by sample preparation, and consistent across techniques. First, we compared lignin's freezing temperature across different drop freezing instruments, including on DRINCZ and LINDA, and then determined an empirical fit parameter for future drop freezing validations. Subsequently, we showed that commercial lignin has consistent ice-nucleating activity across product batches and demonstrated that the ice-nucleating ability of aqueous lignin solutions is stable over time. With these findings, we present lignin as a good immersion freezing standard for future DFT intercomparisons in the research field of atmospheric ice nucleation.


2019 ◽  
Vol 19 (19) ◽  
pp. 12397-12412 ◽  
Author(s):  
Nadine Borduas-Dedekind ◽  
Rachele Ossola ◽  
Robert O. David ◽  
Lin S. Boynton ◽  
Vera Weichlinger ◽  
...  

Abstract. An organic aerosol particle has a lifetime of approximately 1 week in the atmosphere during which it will be exposed to sunlight. However, the effect of photochemistry on the propensity of organic matter to participate in the initial cloud-forming steps is difficult to predict. In this study, we quantify on a molecular scale the effect of photochemical exposure of naturally occurring dissolved organic matter (DOM) and of a fulvic acid standard on its cloud condensation nuclei (CCN) and ice nucleation (IN) activity. We find that photochemical processing, equivalent to 4.6 d in the atmosphere, of DOM increases its ability to form cloud droplets by up to a factor of 2.5 but decreases its ability to form ice crystals at a loss rate of −0.04 ∘CT50 h−1 of sunlight at ground level. In other words, the ice nucleation activity of photooxidized DOM can require up to 4 ∘C colder temperatures for 50 % of the droplets to activate as ice crystals under immersion freezing conditions. This temperature change could impact the ratio of ice to water droplets within a mixed-phase cloud by delaying the onset of glaciation and by increasing the supercooled liquid fraction of the cloud, thereby modifying the radiative properties and the lifetime of the cloud. Concurrently, a photomineralization mechanism was quantified by monitoring the loss of organic carbon and the simultaneous production of organic acids, such as formic, acetic, oxalic and pyruvic acids, CO and CO2. This mechanism explains and predicts the observed increase in CCN and decrease in IN efficiencies. Indeed, we show that photochemical processing can be a dominant atmospheric ageing process, impacting CCN and IN efficiencies and concentrations. Photomineralization can thus alter the aerosol–cloud radiative effects of organic matter by modifying the supercooled-liquid-water-to-ice-crystal ratio in mixed-phase clouds with implications for cloud lifetime, precipitation patterns and the hydrological cycle.Highlights. During atmospheric transport, dissolved organic matter (DOM) within aqueous aerosols undergoes photochemistry. We find that photochemical processing of DOM increases its ability to form cloud droplets but decreases its ability to form ice crystals over a simulated 4.6 d in the atmosphere. A photomineralization mechanism involving the loss of organic carbon and the production of organic acids, CO and CO2 explains the observed changes and affects the liquid-water-to-ice ratio in clouds.


2020 ◽  
Author(s):  
Sophie Bogler ◽  
Nadine Borduas-Dedekind

Abstract. 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.


2020 ◽  
Vol 20 (23) ◽  
pp. 14509-14522
Author(s):  
Sophie Bogler ◽  
Nadine Borduas-Dedekind

Abstract. 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 co-exist. 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 forming a template for 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 subcomponent of atmospheric organic matter, the biopolymer lignin. Ice nucleation experiments were conducted in our custom-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 milligram of 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. Only harsh conditions such as heating to 260 ∘C and addition of a mixture with a ratio of 1 : 750 of grams of lignin to millilitres of hydrogen peroxide were able to decrease lignin's IN activity to the instrument's background level. Next, photochemical and ozone bubbling 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. They further contribute to the understanding of how soluble organic material in the atmosphere can nucleate ice.


2020 ◽  
Author(s):  
Nadine Borduas-Dedekind ◽  
Anna Miller ◽  
Sophie Bogler ◽  
Jon Went

<p>Cloud glaciation is an atmospheric process with important implications for climate and weather. Indeed, clouds made of liquid water and of ice crystals impact the global radiative balance of the atmosphere by reflecting incoming solar radiation and by absorbing outgoing terrestrial radiation. The relevance of ice nucleating particles (INPs) to the atmosphere depends on three main factors, namely on (1) their atmospheric concentration, (2) their freezing temperature and relative humidity, and (3) their freezing mechanism (Cziczo et al., 2013). Research on characterizing ice nucleating organic matter often takes a “top-down” approach where a whole sample of a complex mixture of organic, often biological, macromolecules is subjected to separation techniques and heat treatments to identify IN active sub-components. Studies have used this approach for characterizing bulk soil organic matter, volcanic ash and biological macromolecules from pollen, fungi, and bacteria.</p><p> </p><p>We and others have recently found that dissolved organic matter collected from rivers and swamps surprisingly contain active INP (Borduas-Dedekind et al., 2019; Knackstedt et al., 2018; Moffett et al., 2018). Yet, all three studies state that it is unclear which sub-component of the dissolved organic matter is responsible for the ice nucleating ability. There are clear challenges in attributing the ice nucleating ability when starting with a complex mixture of organic and/or biological material, including matrix effects, impurities accumulated through the separation and/or heating process and lack of molecule identity.</p><p> </p><p>We present here a “bottom-up” approach to compliment the top-down approach for atmospheric ice nucleation research of macromolecules. Using our home-built drop Freezing Ice Nuclei Counter (FINC) with automated imaging, a range of macromolecules were investigated. Indeed, we have analysed a wide range of dissolved organic matter subcomponents including proteins and fulvic acids. We find a range of ice nucleating ability. We find that lignin, the second most abundant biopolymer in plants, is ice active with 50% frozen fraction temperatures (T<sub>50</sub>) at –18 °C at a concentration of 100 mg C/L. Furthermore, we have investigated the ice nucleation ability of common diatom exudates and found that at atmospherically relevant concentration they are likely not ice active in immersion freezing within the detection of our FINC instrument. We are currently investigating the effect of atmospheric processing on these macromolecules with the goal of understanding how macromolecules’ ice activity evolves over their one-week lifetime in the atmosphere.</p>


2020 ◽  
Vol 74 (3) ◽  
pp. 142-148
Author(s):  
Nadine Borduas-Dedekind ◽  
Sergey Nizkorodov ◽  
Kristopher McNeill

During their atmospheric lifetime, organic compounds within aerosols are exposed to sunlight and undergo photochemical processing. This atmospheric aging process changes the ability of organic aerosols to form cloud droplets and consequently impacts aerosol–cloud interactions. We recently reported changes in the cloud forming properties of aerosolized dissolved organic matter (DOM) due to a photomineralization mechanism, transforming high-molecular weight compounds in DOM into organic acids, CO and CO2. To strengthen the implications of this mechanism to atmospheric aerosols, we now extend our previous dataset and report identical cloud activation experiments with laboratory-generated secondary organic aerosol (SOA) extracts. The SOA was produced from the oxidation of α-pinene and naphthalene, a representative biogenic and anthropogenic source of SOA, respectively. Exposure of aqueous solutions of SOA to UVB irradiation increased the dried organic material's hygroscopicity and thus its ability to form cloud droplets, consistent with our previous observations for DOM. We propose that a photomineralization mechanism is also at play in these SOA extracts. These results help to bridge the gap between DOM and SOA photochemistry by submitting two differently-sourced organic matter materials to identical experimental conditions for optimal comparison.


2018 ◽  
Vol 11 (7) ◽  
pp. 3969-3985 ◽  
Author(s):  
Jessie M. Creamean ◽  
Katherine M. Primm ◽  
Margaret A. Tolbert ◽  
Emrys G. Hall ◽  
Jim Wendell ◽  
...  

Abstract. Aerosols have a profound impact on cloud microphysics through their ability to serve as ice nucleating particles (INPs). As a result, cloud radiative properties and precipitation processes can be modulated by such aerosol–cloud interactions. However, one of the largest uncertainties associated with atmospheric processes is the indirect effect of aerosols on clouds. The need for more advanced observations of INPs in the atmospheric vertical profile is apparent, yet most ice nucleation measurements are conducted on the ground or during infrequent and intensive airborne field campaigns. Here, we describe a novel measurement platform that is less expensive and smaller (< 5 kg) when compared to traditional aircraft and tethered balloon platforms and that can be used for evaluating two modes of ice nucleation (i.e., immersion and deposition). HOVERCAT (Honing On VERtical Cloud and Aerosol properTies) flew during a pilot study in Colorado, USA, up to 2.6 km above mean sea level (1.1 km above ground level) and consists of an aerosol module that includes an optical particle counter for size distributions (0.38–17 µm in diameter) and a new sampler that collects up to 10 filter samples for offline ice nucleation and aerosol analyses on a launched balloon platform. During the May 2017 test flight, total particle concentrations were highest closest to the ground (up to 50 cm−3 at < 50 m above ground level) and up to 2 in 102 particles were ice nucleation active in the immersion mode (at −23 ∘C). The warmest temperature immersion and deposition mode INPs (observed up to −6 and −40.4 ∘C, respectively) were observed closest to the ground, but overall INP concentrations did not exhibit an inverse correlation with increasing altitude. HOVERCAT is a prototype that can be further modified for other airborne platforms, including tethered balloon and unmanned aircraft systems. The versatility of HOVERCAT affords future opportunities to profile the atmospheric column for more comprehensive evaluations of aerosol–cloud interactions. Based on our test flight experiences, we provide a set of recommendations for future deployments of similar measurement systems and platforms.


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