On the impacts of phytoplankton-derived organic matter on the properties of the primary marine aerosol – Part 2: Composition, hygroscopicity and cloud condensation activity

Abstract. The effect of colloidal and dissolved organic matter <0.2 μm, secreted by marine biota, on the hygroscopic growth and droplet activation behaviour of the primary marine aerosol was studied. Seawater proxies were prepared by the combination of artificial seawater devoid of marine organics and natural seawater enriched in organic exudate released by laboratory-grown phytoplankton cultures, as described in a companion paper. The primary aerosol was produced by bubble bursting, using a plunging multijet system as an aerosol generator. The aerosol generated from seawater proxies enriched with marine exudate presented organic volume fractions on the order of 5–37%, as derived by applying a simple mixing rule. The hygroscopic growth and cloud condensation nuclei (CCN) activity of the marine organics-enriched particles where 9–17% and 5–24% lower, respectively, than those of the aerosol produced from artificial seawater devoid of exudate. Experiments in a companion paper indicated that the cloud nuclei formation could be enhanced in diatom bloom areas because of the increase in the primary particle production induced by marine organics. The experiments in the present study, however, indicate that the impacts of such an enhancement would be counteracted by the reduction in the CCN activity of the primary particles enriched in marine organics. The extent of the effect of the biogenic matter on the particle behaviour was dependent on the seawater organic concentration and type of algal exudate. Aerosol produced from seawater proxies containing diatomaceous exudate presented higher hydrophobicity and lower CCN activity than those enriched with nanoplankton exudate. The organic fraction of the particles increased with increasing seawater organic concentration, with the highest organic enrichment found for the diatomaceous exudate. These findings are indicative that, besides the differences induced by the aerosol generator employed, discrepancies between different studies in the behaviour of the organics-enriched primary seaspray could partly be explained by the difference in the nature and concentration of the organic material in the source seawater employed. Consistently across the experiments, theoretical analysis based on the Köhler model predicted a reduction in the primary seaspray CCN activity upon the incorporation of marine organics into the particle composition. This effect is consequence of the replacement of small inorganic sea salt molecules by large molar mass organic molecules, together with a moderate suppression of the surface tension at the point of activation of 5–0.5%, which leads to a dominance of the reduction in the dissolved solute in the Raoult term.

Download Full-text

On the impacts of phytoplankton-derived organic matter on the properties of the primary marine aerosol – Part 2: Composition, hygroscopicity and cloud condensation activity

Atmospheric Chemistry and Physics ◽

10.5194/acp-11-2585-2011 ◽

2011 ◽

Vol 11 (6) ◽

pp. 2585-2602 ◽

Cited By ~ 76

Author(s):

E. Fuentes ◽

H. Coe ◽

D. Green ◽

G. McFiggans

Keyword(s):

Organic Matter ◽

Particle Production ◽

Cloud Condensation Nuclei ◽

Companion Paper ◽

Artificial Seawater ◽

Natural Seawater ◽

Marine Biota ◽

Marine Aerosol ◽

Hygroscopic Growth ◽

Ccn Activity

Abstract. The effect of nanogel colloidal and dissolved organic matter <0.2 μm, secreted by marine biota, on the hygroscopic growth and droplet activation behaviour of the primary marine aerosol was studied. Seawater proxies were prepared by the combination of artificial seawater devoid of marine organics and natural seawater enriched in organic exudate released by laboratory-grown phytoplankton cultures, as described in a companion paper. The primary aerosol was produced by bubble bursting, using a plunging multijet system as an aerosol generator. The aerosol generated from seawater proxies enriched with marine exudate presented organic volume fractions on the order of 8–37%, as derived by applying a simple mixing rule. The hygroscopic growth and cloud condensation nuclei (CCN) activity of the marine organics-enriched particles where 9–17% and 5–24% lower, respectively, than those of the aerosol produced from artificial seawater devoid of exudate. Experiments in a companion paper indicated that the cloud nuclei formation could be enhanced in diatom bloom areas because of the increase in the primary particle production induced by marine organics. The experiments in the present study, however, indicate that the impacts of such an enhancement would be counteracted by the reduction in the CCN activity of the primary particles enriched in marine organics. The extent of the effect of the biogenic matter on the particle behaviour was dependent on the seawater organic concentration and type of algal exudate. Aerosol produced from seawater proxies containing diatomaceous exudate presented higher hydrophobicity and lower CCN activity than those enriched with nanoplankton exudate. The organic fraction of the particles was found to correlate with the seawater organic concentration, without observing saturation of the particle organic mass fraction even for unrealistically high organic matter concentration in seawater. These findings are indicative that discrepancies on the composition of the primary aerosol between different studies could partly be explained by the difference in the nature and concentration of the organic matter in the source seawater employed. Consistently across the experiments, theoretical analysis based on the Köhler model predicted a reduction in the primary marine aerosol CCN activity upon the incorporation of marine organics into the particle composition. This effect is consequence of the replacement of small inorganic sea salt molecules by large molar mass organic molecules, together with a moderate suppression of the surface tension at the point of activation of 5–0.5%, which leads to a dominance of the reduction in the dissolved solute in the Raoult term.

Download Full-text

The Influence of Algal Exudate on the Hygroscopicity of Sea Spray Particles

Advances in Meteorology ◽

10.1155/2010/365131 ◽

2010 ◽

Vol 2010 ◽

pp. 1-11 ◽

Cited By ~ 12

Author(s):

H. Wex ◽

E. Fuentes ◽

G. Tsagkogeorgas ◽

J. Voigtländer ◽

T. Clauss ◽

...

Keyword(s):

Organic Matter ◽

Aerosol Particles ◽

Algal Species ◽

Artificial Seawater ◽

Time Range ◽

Sea Spray ◽

Marine Aerosol ◽

Hygroscopic Growth ◽

Droplet Activation ◽

Kinetic Effects

We examined the effect of organic matter released by four different algal species on the hygroscopic growth and droplet activation behaviour of laboratory-generated marine aerosol particles. Hygroscopic growth factors and dry diameters for activation were reduced by less than 10%, compared to that of sodium chloride or of artificial seawater that was devoid of marine surfactants. Concentration-dependent nonideal behaviour was observed for the artificial seawater. But within measurement uncertainty, the measured hygroscopic growth and droplet activation behaviour for the samples that contained organic matter were consistent with a hygroscopicity parameter that was constant between the sub- and supersaturated measurement points. Also, the hygroscopic growth measured for hydrated particles after 3 and after 10 seconds was similar, which implies that in this time range no kinetic effects were detected.

Download Full-text

Study on Analysis and Sedimentation of Alumina Nanoparticles

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph16030510 ◽

2019 ◽

Vol 16 (3) ◽

pp. 510 ◽

Cited By ~ 1

Author(s):

Xuehong Zheng ◽

Yuehan Li ◽

Ding Chen ◽

Airong Zheng ◽

Qikang Que

Keyword(s):

Organic Matter ◽

Dissolved Organic Matter ◽

Ecological Risk ◽

Sedimentation Rate ◽

Aquatic Environment ◽

Artificial Seawater ◽

Alumina Nanoparticles ◽

Natural Seawater ◽

Ultrasonic Dispersion ◽

Risk Effects

Dispersion and aggregation behavior of nanoparticles in aquatic environment may be affected by pH, salinity, and dissolved organic matter, which would change its ecological risk. Effects of time, power and temperature on the alumina nanoparticles (nano-Al2O3) ultrasonic dispersion in water were discussed. Al2O3 had a best ultrasonic dispersion for 30 min at 105 W and 30 °C. The concentration of Al2O3 could be measured by ultraviolet (UV) spectrophotometer, and the method was efficient and accurate. Furthermore, the sedimentation rate of Al2O3 was related to pH, salinity, and its concentration in the artificial seawater. When pH was 7.31, approaching the isoelectric point of Al2O3, they aggregated and settled fastest. Settlement coefficient (k) of Al2O3 increased by 3 and 2.7 times while the salinity and its concentration increased. The sedimentation rate was higher in natural seawater than that in artificial seawater. All results indicated that nano-Al2O3 would be removed in aquatic environment.

Download Full-text

Mixing State of Submicrometer Sea Spray Particles Enriched by Insoluble Species in Bubble-Bursting Experiments

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech-d-13-00086.1 ◽

2014 ◽

Vol 31 (1) ◽

pp. 93-104 ◽

Cited By ~ 15

Author(s):

Ji Yeon Park ◽

Sungil Lim ◽

Kihong Park

Keyword(s):

Organic Matter ◽

Membrane Filtration ◽

Volume Fraction ◽

Silica Particles ◽

Artificial Seawater ◽

Sea Spray ◽

Natural Seawater ◽

Mixing State ◽

High Concentration ◽

Dissolved Salts

Abstract Measurements of size distribution, hygroscopicity, and volatility of submicrometer sea spray particles produced by the bubble busting of artificial and natural seawater were conducted to determine their mixing state and volume fractions of hygroscopic and nonhygroscopic species or volatile and nonvolatile species. The particles sprayed from artificial seawater having insoluble silica particles were found to be an external mixture of two groups of particles having hygroscopic growth factors (HGFs) of 1.33 (an internal mixture of nonhygroscopic silica particles and hygroscopic salt species) and 1.68 (a similar mixture having more salt species) when the mass ratio of insoluble particles to dissolved salts was higher than 2. For sea spray particles from natural seawater, the external mixing was not significantly observed because of a high concentration of dissolved salts. The HGFs of sea spray particles (80–140 nm) from natural seawater were in the range of 1.70–1.76, which were lower than from pure artificial seawater (1.87), and the HGFs had no change before and after membrane filtration of seawater, suggesting that the sea spray particles from natural seawater contained a significant amount of nonhygroscopic dissolved organic matter in addition to hygroscopic salt species. The volume fraction of the nonhygroscopic species ranged from 20% to 29%, and the highest value was observed for seawater samples from the site where strong biological activity occurred, suggesting that biological materials played an important role in the formation of nonhygroscopic organic matter. Volatility measurements also identified the existence of volatile organic species in single particles from natural seawater, with the volume fraction of volatile species evaporated at 100°C being 4%–5%.

Download Full-text

Hygroscopic and volatile properties of marine aerosol observed at Cape Grim during the P2P campaign

Environmental Chemistry ◽

10.1071/en07011 ◽

2007 ◽

Vol 4 (3) ◽

pp. 162 ◽

Cited By ~ 34

Author(s):

Catherine A. Fletcher ◽

Graham R. Johnson ◽

Zoran D. Ristovski ◽

Mike Harvey

Keyword(s):

Organic Matter ◽

Ammonium Sulfate ◽

Organic Content ◽

Major Influence ◽

Radiation Balance ◽

Marine Aerosol ◽

Marine Aerosols ◽

Hygroscopic Growth ◽

Accumulation Mode ◽

Cape Grim

Environmental context. The marine environment covers 71% of the Earth’s surface, and accounts for most of the planet’s cloud cover. Water droplets in these clouds all form on pre-existing marine aerosol particles. The number, size and composition of these particles determine the cloud droplet size and consequently, the cloud’s light scattering and precipitation behaviour. Marine aerosols, therefore, have a major influence on the planet’s radiation balance and climate. The origin of marine aerosols is still not completely resolved. The newly developed VH-TDMA technique has been applied to marine aerosols that come from the Southern Ocean. The technique enabled new insights into the composition and structure of these aerosols. It has been found that organic matter constitutes 20–40% of these particles, which suppresses their hygroscopic growth. Abstract. Simultaneous measurement of particle hygroscopic and volatile properties was performed using a VH-TDMA on both Aitken and accumulation mode particles. In addition, deliquescence measurements at different thermodenuder temperatures were also performed. The measurements were part of the P2P campaign which took place in February 2006 at the Cape Grim monitoring station in Tasmania, Australia. During baseline conditions, there was often a volatilisation step that occurred below 125°C in the volatility scans, where up to 25% of the volume is lost. Analysis of the changes in growth as this took place indicates that different substances are responsible for this volatilisation on different days – ammonium nitrate, sulfuric acid, or a volatile non-hygroscopic organic. The major volatilisation in all cases occurred in the temperature range ~140–200°C, which is taken to indicate the presence of ammonium sulfate or ammonium bisulfate. A degree of growth suppression is generally evident before this volatilisation, which indicates that a non-hygroscopic material with a similar volatility to ammonium sulfate/bisulfate may be present, which cannot be distinguished in the volatility scans. Organic matter was typically present at around ~20–40% for these particles. When Aitken and accumulation mode particles were measured on the same day, it was found that the organic content of the smaller particles tended to be higher than the larger particles by roughly 20 percentage points.

Download Full-text

Laboratory-generated primary marine aerosol via bubble-bursting and atomization

Atmospheric Measurement Techniques ◽

10.5194/amt-3-141-2010 ◽

2010 ◽

Vol 3 (1) ◽

pp. 141-162 ◽

Cited By ~ 102

Author(s):

E. Fuentes ◽

H. Coe ◽

D. Green ◽

G. de Leeuw ◽

G. McFiggans

Keyword(s):

Particle Production ◽

Active Material ◽

Condensation Nucleus ◽

Bubble Surface ◽

Cloud Condensation Nucleus ◽

Small Scale ◽

Natural Seawater ◽

Bubble Bursting ◽

Aerosol Generator ◽

Aerosol Properties

Abstract. A range of bubble and sea spray aerosol generators has been tested in the laboratory and compared with oceanic measurements from the literature. We have shown that the method of generation has a significant influence on the properties of the aerosol particles produced. Hence, the validity of a generation system to mimic atmospheric aerosol is dependent on its capacity for generating bubbles and particles in a realistic manner. A bubble-bursting aerosol generator which produces bubbles by water impingement was shown to best reproduce the oceanic bubble spectral shapes, which confirms previous findings. Two porous bubblers and a plunging-water jet system were tested as bubble-bursting aerosol generators for comparison with a standard nebulizer. The methods for aerosol production were evaluated by analysing the bubble spectrum generated by the bubble-bursting systems and the submicron size distribution, hygroscopicity and cloud condensation nucleus activity of the aerosols generated by the different techniques. Significant differences in the bubble spectrum and aerosol properties were observed when using different aerosol generators. The aerosols generated by the different methods exhibited similar hygroscopicity and cloud condensation nucleus activity behaviour when a sample of purely inorganic salts was used as a parent seawater solution; however, significant differences in the aerosol properties were found when using samples of filtered natural seawater enriched with biogenic organics. The presence of organics in the aerosol caused suppression of the growth factor at humidities above 75% RH and an increase in the critical supersaturation with respect to the generation from artificial seawater devoid of organics. The extent of the effect of organics on the aerosol properties varied depending on the method of particle production. The results of this work indicate that the aerosol generation mechanism affects the particles organic enrichment, thus the behaviour of the produced aerosols strongly depends on the laboratory aerosol generator employed. Comparison between bubble lifetimes in several laboratory simulations and the oceanic conditions indicated that it would require a considerable extension of the dimensions of the currently used bubble-bursting laboratory systems in order to replicate the characteristic oceanic bubble lifetimes. We analyzed the implications derived from the reduced bubble residence times in scaled systems, regarding marine surfactants adsorption on rising bubbles, and found that adsorption equilibrium is reached on a timescale much shorter than the bubble lifetime in small-scale laboratory generators. This implies that adsorption of marine surface-active material is not limited by surfactant transport to the bubble surface.

Download Full-text

Organic Matter Cycling

Biogeochemistry of Estuaries ◽

10.1093/oso/9780195160826.003.0017 ◽

2006 ◽

Author(s):

Thomas S. Bianchi

Keyword(s):

Organic Matter ◽

Salt Marshes ◽

Vascular Plant ◽

World Ocean ◽

Analytical Techniques ◽

Marine Biota ◽

Natural Ecosystems ◽

Redfield Ratio ◽

Structural Support ◽

Transformation Of Organic Matter

In this chapter the general processes involved in controlling production and transformation of organic matter will be discussed as well as some of the associated stoichiometric changes of a few key biological elements (e.g., C, N, P, S). Stoichiometry is defined as the mass balance of chemical reactions as they relate to the law of definite proportions and conservation of mass (Sterner and Elser, 2002). For example, if we examine the average atomic ratios of C, N, and P in phytoplankton we see a relatively consistent ratio of 106:16:1 in most marine species. This is perhaps the best example of applied stoichiometric principles in natural ecosystems and is derived from the classic work of Alfred C. Redfield (1890–1983) (Redfield, 1958; Redfield et al., 1963). More specifically, Redfield compared the ratios of C, N, and P of dissolved nutrients in marine waters to that of suspended marine particulate matter (seston) (essentially phytoplankton) and found straight lines with equal slopes (figure 8.1; Redfield et al., 1963). This relationship suggested that marine biota were critical in determining the chemistry of the world ocean, clearly one of the most important historical findings linking chemical and biological oceanography (Falkowski, 2000). Moreover, the Redfield ratio has been further validated with recent data using improved analytical techniques (Karl et al., 1993; Hoppema and Goeyens, 1999). Other work has shown that there are predictable deviations from the Redfield ratio across a freshwater to open ocean marine gradient (figure 8.2; Downing, 1997). For example, N-to-P ratios in estuaries have commonly been shown to be lower and/or higher than the predicted Redfield ratio because of denitrification and anthropogenic nutrient enrichment processes, respectively. Inputs of vascular plant organic matter (e.g., mangroves, salt marshes, seagrasses) to estuarine systems presents another problem in causing deviations of C:N:P from the Redfield ratio. Vascular plants have been shown to deviate from this ratio in part because of relatively high amounts of C and N compared to algae due to a higher abundance of structural support molecules (e.g., cellulose, lignin) and defense antiherbivory (secondary) compounds (e.g., tannins), respectively (Vitousek et al., 1988).

Download Full-text

Photoproduction of nitric oxide in seawater

Ocean Science ◽

10.5194/os-16-135-2020 ◽

2020 ◽

Vol 16 (1) ◽

pp. 135-148 ◽

Cited By ~ 1

Author(s):

Ye Tian ◽

Gui-Peng Yang ◽

Chun-Ying Liu ◽

Pei-Feng Li ◽

Hong-Tao Chen ◽

...

Keyword(s):

Nitric Oxide ◽

North Pacific Ocean ◽

Artificial Seawater ◽

Natural Seawater ◽

Factors Affecting ◽

Decreasing Ph ◽

Seawater Samples ◽

Major Factors ◽

Increasing Temperature ◽

Increasing Trends

Abstract. Nitric oxide (NO) is a short-lived intermediate of the oceanic nitrogen cycle. However, our knowledge about its production and consumption pathways in oceanic environments is rudimentary. In order to decipher the major factors affecting NO photochemical production, we irradiated several artificial seawater samples as well as 31 natural surface seawater samples in laboratory experiments. The seawater samples were collected during a cruise to the western tropical North Pacific Ocean (WTNP, a N–S section from 36 to 2∘ N along 146 to 143∘ E with 6 and 12 stations, respectively, and a W–E section from 137 to 161∘ E along the Equator with 13 stations) from November 2015 to January 2016. NO photoproduction rates from dissolved nitrite in artificial seawater showed increasing trends with decreasing pH, increasing temperature, and increasing salinity. In contrast, NO photoproduction rates (average: 0.5±0.2×10-12 mol L−1 s−1) in the natural seawater samples from the WTNP did not show any correlations with pH, water temperature, salinity, or dissolved inorganic nitrite concentrations. The flux induced by NO photoproduction in the WTNP (average: 13×10-12 mol m−2 s−1) was significantly larger than the NO air–sea flux density (average: 1.8×10-12 mol m−2 s−1), indicating a further NO loss process in the surface layer.

Download Full-text

A single parameter representation of hygroscopic growth and cloud condensation nucleus activity – Part 2: Including solubility

Atmospheric Chemistry and Physics ◽

10.5194/acp-8-6273-2008 ◽

2008 ◽

Vol 8 (20) ◽

pp. 6273-6279 ◽

Cited By ~ 132

Author(s):

M. D. Petters ◽

S. M. Kreidenweis

Keyword(s):

Unit Volume ◽

Condensation Nucleus ◽

Single Parameter ◽

Saturated Solution ◽

Cloud Condensation Nucleus ◽

Hygroscopic Growth ◽

Solubility In Water ◽

Parameter Representation ◽

Model Complex ◽

Ccn Activity

Abstract. The ability of a particle to serve as a cloud condensation nucleus in the atmosphere is determined by its size, hygroscopicity and its solubility in water. Usually size and hygroscopicity alone are sufficient to predict CCN activity. Single parameter representations for hygroscopicity have been shown to successfully model complex, multicomponent particles types. Under the assumption of either complete solubility, or complete insolubility of a component, it is not necessary to explicitly include that component's solubility into the single parameter framework. This is not the case if sparingly soluble materials are present. In this work we explicitly account for solubility by modifying the single parameter equations. We demonstrate that sensitivity to the actual value of solubility emerges only in the regime of 2×10−1–5×10−4, where the solubility values are expressed as volume of solute per unit volume of water present in a saturated solution. Compounds that do not fall inside this sparingly soluble envelope can be adequately modeled assuming they are either infinitely soluble in water or completely insoluble.

Download Full-text