Sum-Frequency Generation Spectroscopy for Studying Organic Layers at Water-Air Interfaces: Microlayer Monitoring and Surface Reactivity

NASA Astrophysics Data System (ADS)

Laß, Kristian; Kleber, Joscha; Bange, Hermann; Friedrichs, Gernot

2015-04-01

The sea surface microlayer, according to commonly accepted terminology, comprises the topmost millimetre of the oceanic water column. It is often enriched with organic matter and is directly influenced by sunlight exposure and gas exchange with the atmosphere, hence making it a place for active biochemistry and photochemistry as well as for heterogeneous reactions. In addition, surface active material either is formed or accumulates directly at the air-water interface and gives rise to very thin layers, sometimes down to monomolecular thickness. This "sea surface nanolayer" determines the viscoelastic properties of the seawater surface and thus may impact the turbulent air-sea gas exchange rates. To this effect, this small scale layer presumably plays an important role for large scale changes of atmospheric trace gas concentrations (e.g., by modulating the ocean carbon sink characteristics) with possible implications for coupled climate models. To date, detailed knowledge about the composition, structure, and reactivity of the sea surface nanolayer is still scarce. Due to its small vertical dimension and the small amount of material, this surfactant layer is very difficult to separate and analyse. A way out is the application of second-order nonlinear optical methods, which make a direct surface-specific and background-free detection of this interfacial layer possible. In recent years, we have introduced the use of vibrational sum frequency generation (VSFG) spectroscopy to gain insight into natural and artificial organic monolayers at the air-water interface. In this contribution, the application of VSFG spectroscopy for the analysis of the sea surface nanolayer will be illustrated. Resulting spectra are interpreted in terms of layer composition and surfactant classes, in particular with respect to carbohydrate-containing molecules such as glycolipids. The partitioning of the detected surfactants into soluble and non-soluble ("wet" and "dry") surfactants will be discussed. Furthermore, the application of a combined VSFG/Langmuir trough experiment to investigate the reaction kinetics of heterogeneous oxidation processes will be highlighted. The ozonolysis of monolayers of unsaturated fatty acids serves as model system for natural aging processes of surfactant layers at the sea surface. Finally, a VSFG time series study of the sea surface nanolayer at a western Baltic Sea near-shore sampling station will be presented. The observed seasonality reveals a significant temporal shift with respect to the spring algal bloom showing that high organic material content in the microlayer does not necessarily correlate with high nanolayer abundance. This interesting finding and implications for the formation of surfactant material by degradation of biological material will be discussed briefly.

Glyoxal and Methylglyoxal in Atlantic Seawater and marine Aerosol Particles

NASA Astrophysics Data System (ADS)

van Pinxteren, Manuela; Herrmann, Hartmut

2014-05-01

The two α-dicarbonyls glyoxal (CHOCHO; GLY) and methylglyoxal (CH3COCHO; MGLY) have attracted increasing attention over the past years because of their potential role in secondary organic aerosol formation. Recently Sinreich et al. (2010) suggested the open ocean as an important (so far unknown) source for GLY in the atmosphere. To date, there are few available field data of these compounds in the marine area. In this study we present measurements of GLY and MGLY in seawater and marine aerosol particles sampled during a transatlantic Polarstern cruise in spring 2011. In seawater we especially investigated the sea surface microlayer (sampled with the glass plate technique) as it is the direct interface between ocean and atmosphere. Analytical measurements were based on derivatisation with o-(2,3,4,5,6-Pentafluorobenzyl)-hydroxylamine reagent, solvent extraction and GC-MS (SIM) analysis. The results show that GLY and MGLY are present in the sea surface microlayer of the ocean and corresponding bulkwater with average concentrations of 228 ng L-1 (GLY) and 196 ng L-1 (MGLY). Significant enrichment (factor of 4) of GLY and MGLY in the sea surface microlayer was found implying photochemical production of the two carbonyls though a clear connection to global radiation was not observed. On aerosol particles, both carbonyls were detected (average concentration 0.2 ng m-3) and are strongly connected to each other, suggesting similar formation mechanisms. Both carbonyls show a very good correlation with particulate oxalate, supporting the idea of a secondary formation of oxalic acid via GLY and MGLY. A slight correlation of the two carbonyls in the sea surface microlayer and in the aerosol particles was found at co-located sampling areas. In summary, the results of GLY and MGLY in marine aerosol particles and in the oceanic water give first insights towards interaction processes of these alpha dicarbonyls between ocean and atmosphere (van Pinxteren and Herrmann (2013)). References: Sinreich et al., Ship-based detection of glyoxal over the remote tropical Pacific Ocean. Atmos. Chem. Phys. 10(23), 11359-11371 (2010). van Pinxteren and Herrmann, Glyoxal and Methylglyoxal in Atlantic Seawater and marine Aerosol Particles: Method development and first application during the Polarstern cruise ANT XXVII/4. Atmos. Chem. Phys. 13, 11791-11802 (2013).

Model and Assessment of the Contribution of Dredged Material Disposal to Sea-Surface Contamination in Puget Sound

DTIC Science & Technology

1986-02-01

DISPOSAL TO SEA-SURFACE CONTAMINATION IN PUGET SOUND J. T., Hardy Marine Research Laboratory Sequim , Washington C. E. Cowan Pacific Northwest Laboratory...spawning season. ( 1 I -"I CONCLUSIONS AND RECOMMENDATIONS Significant SSM contamination and toxicity already exists in Elliott Bay . Dredge dieposal could...disposal area of 900 ft. Typical contaminant concentrations on dredged material and baseline concentrations in the microlayer of Elliott Bay (Hardy et

Respiratory Microbiome of Endangered Southern Resident Killer Whales and Microbiota of Surrounding Sea Surface Microlayer in the Eastern North Pacific.

PubMed

Raverty, Stephen A; Rhodes, Linda D; Zabek, Erin; Eshghi, Azad; Cameron, Caroline E; Hanson, M Bradley; Schroeder, J Pete

2017-03-24

In the Salish Sea, the endangered Southern Resident Killer Whale (SRKW) is a high trophic indicator of ecosystem health. Three major threats have been identified for this population: reduced prey availability, anthropogenic contaminants, and marine vessel disturbances. These perturbations can culminate in significant morbidity and mortality, usually associated with secondary infections that have a predilection to the respiratory system. To characterize the composition of the respiratory microbiota and identify recognized pathogens of SRKW, exhaled breath samples were collected between 2006-2009 and analyzed for bacteria, fungi and viruses using (1) culture-dependent, targeted PCR-based methodologies and (2) taxonomically broad, non-culture dependent PCR-based methodologies. Results were compared with sea surface microlayer (SML) samples to characterize the respective microbial constituents. An array of bacteria and fungi in breath and SML samples were identified, as well as microorganisms that exhibited resistance to multiple antimicrobial agents. The SML microbes and respiratory microbiota carry a pathogenic risk which we propose as an additional, fourth putative stressor (pathogens), which may adversely impact the endangered SRKW population.

Macrophyte disturbance alters aquatic surface microlayer structure, metabolism, and fate.

PubMed

Seliskar, Denise M; Gallagher, John L

2014-03-01

Macrophytes drive the functioning of many salt marsh ecosystem components. We questioned how temporary clearing of the macrophyte community, during restoration, would impact processes at the scale of the aquatic surface microlayer. Development, deposition, and breakup of the tidal creek surface microlayer were followed over tidal cycles seasonally in a cleared "former" Phragmites marsh and an adjacent restored Spartina marsh. Metabolic and physical processes of the mobile surface microlayers and underlying water were compared, along with distribution of organic and inorganic components onto simulated plant stems. In July and October, chlorophyll-a quantities were less on simulated stems in the cleared site than in the restored site. The aquatic microlayer in the cleared site creek exhibited lower photosynthesis and respiration rates, fewer diatoms and green algae, and less chlorophyll-a. There was a lower concentration (250 times) and reduced diversity of fatty acids in the surface microlayer of the cleared site, reflecting a smaller and less diverse microbial community and reduced food resources. Fiddler crab activity was an order of magnitude higher where macrophytes had been cleared. Their consumption of edaphic algae on the mud surface may account for the reduced algae and other organics in the creek surface microlayer, thus representing a redirection of this food resource from creek consumers. Overall, there were less total particulates in the creek surface microlayer at the cleared site, and they dropped out of the surface microlayer sooner in the tidal cycle, resulting in a lower sediment load available for deposit onto marsh surfaces.

Ocean haline skin layer and turbulent surface convections

NASA Astrophysics Data System (ADS)

Zhang, Y.; Zhang, X.

2012-04-01

The ocean haline skin layer is of great interest to oceanographic applications, while its attribute is still subject to considerable uncertainty due to observational difficulties. By introducing Batchelor micro-scale, a turbulent surface convection model is developed to determine the depths of various ocean skin layers with same model parameters. These parameters are derived from matching cool skin layer observations. Global distributions of salinity difference across ocean haline layers are then simulated, using surface forcing data mainly from OAFlux project and ISCCP. It is found that, even though both thickness of the haline layer and salinity increment across are greater than the early global simulations, the microwave remote sensing error caused by the haline microlayer effect is still smaller than that from other geophysical error sources. It is shown that forced convections due to sea surface wind stress are dominant over free convections driven by surface cooling in most regions of oceans. The free convection instability is largely controlled by cool skin effect for the thermal microlayer is much thicker and becomes unstable much earlier than the haline microlayer. The similarity of the global distributions of temperature difference and salinity difference across cool and haline skin layers is investigated by comparing their forcing fields of heat fluxes. The turbulent convection model is also found applicable to formulating gas transfer velocity at low wind.

Microhydrodynamics of flotation processes in the sea surface layer

NASA Astrophysics Data System (ADS)

Grammatika, Marianne; Zimmerman, William B.

2001-10-01

The uppermost surface of the ocean forms a peculiarly important ecosystem, the sea surface microlayer (SML). Comprising the top 1-1000 μm of the ocean surface, the SML concentrates many chemical substances, particularly those that are surface active. Important economically as a nursery for fish eggs and larvae, the SML unfortunately is also especially vulnerable to pollution. Contaminants that settle out from the air, have low solubility, or attach to floatable matter tend to accumulate in the SML. Bubbles contribute prominently to the dynamics of air-sea exchanges, playing an important role in geochemical cycling of material in the upper ocean and SML. In addition to the movement of bubbles, the development of a bubble cloud interrelates with the single particle dynamics of all other bubbles and particles. In the early sixties, several in situ oceanographic techniques revealed an "unbelievably immense" number of coastal bubbles of radius 15-300 μm. The spatial and temporal variation of bubble numbers were studied; acoustical oceanographers now use bubbles as tracers to determine ocean processes near the ocean surface. Sea state and rain noises have both been definitively ascribed to the radiation from huge numbers of infant micro bubbles [The Acoustic Bubble. Academic Press, San Diego]. Our research programme aims at constructing a hydrodynamic model for particle transport processes occurring at the microscale, in multi-phase flotation suspensions. Current research addresses bubble and floc microhydrodynamics as building blocks for a microscale transport model. This paper reviews sea surface transport processes in the microlayer and the lower atmosphere, and identifies those amenable to microhydrodynamic modelling and simulation. It presents preliminary simulation results including the multi-body hydrodynamic mobility functions for the modelling of "dynamic bubble filters" and floc suspensions. Hydrodynamic interactions versus spatial anisotropy and size of particle clouds are investigated.

A marine biogenic source of atmospheric ice-nucleating particles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilson, T. W.; Ladino, L. A.; Alpert, Peter A.

2015-09-09

The formation of ice in clouds is facilitated by the presence of airborne ice nucleating particles1,2. Sea spray is one of the major global sources of atmospheric particles, but it is unclear to what extent these particles are capable of nucleating ice3–11. Here we show that material in the sea surface microlayer, which is enriched in surface active organic material representative of that found in sub-micron sea- spray aerosol12–21, nucleates ice under conditions that occur in mixed-phase clouds and high-altitude ice clouds. The ice active material is likely biogenic and is less than ~0.2 ?m in size. We also showmore » that organic material (exudate) released by a common marine diatom nucleates ice when separated from cells and propose that organic material associated with phytoplankton cell exudates are a candidate for the observed ice nucleating ability of the microlayer samples. By combining our measurements with global model simulations of marine organic aerosol, we show that ice nucleating particles of marine origin are dominant in remote marine environments, such as the Southern Ocean, the North Pacific and the North Atlantic.« less

Dynamic Bubble Surface Tension Measurements in Northwest Atlantic Seawater

NASA Astrophysics Data System (ADS)

Kieber, D. J.; Long, M. S.; Keene, W. C.; Kinsey, J. D.; Frossard, A. A.; Beaupre, S. R.; Duplessis, P.; Maben, J. R.; Lu, X.; Chang, R.; Zhu, Y.; Bisgrove, J.

2017-12-01

Numerous reports suggest that most organic matter (OM) associated with newly formed primary marine aerosol (PMA) originates from the sea-surface microlayer. However, surface-active OM rapidly adsorbs onto bubble surfaces in the water column and is ejected into the atmosphere when bubbles burst at the air-water interface. Here we present dynamic surface tension measurements of bubbles produced in near surface seawater from biologically productive and oligotrophic sites and in deep seawater collected from 2500 m in the northwest Atlantic. In all cases, the surface tension of bubble surfaces decreased within seconds after the bubbles were exposed to seawater. These observations demonstrate that bubble surfaces are rapidly saturated by surfactant material scavenged from seawater. Spatial and diel variability in bubble surface evolution indicate corresponding variability in surfactant concentrations and/or composition. Our results reveal that surface-active OM is found throughout the water column, and that at least some surfactants are not of recent biological origin. Our results also support the hypothesis that the surface microlayer is a minor to negligible source of OM associated with freshly produced PMA.

A rapid method for assessing the accumulation of microplastics in the sea surface microlayer (SML) of estuarine systems.

PubMed

Anderson, Zachary T; Cundy, Andrew B; Croudace, Ian W; Warwick, Phillip E; Celis-Hernandez, Omar; Stead, Jessica L

2018-06-21

Microplastics are an increasingly important contaminant in the marine environment. Depending on their composition and degree of biofouling, many common microplastics are less dense than seawater and so tend to float at or near the ocean surface. As such, they may exhibit high concentrations in the sea surface microlayer (SML - the upper 1-1000 μm of the ocean) relative to deeper water. This paper examines the accumulation of microplastics, in particular microfibres, in the SML in two contrasting estuarine systems - the Hamble estuary and the Beaulieu estuary, southern U.K., via a novel and rapid SML-selective sampling method using a dipped glass plate. Microplastic concentrations (for identified fibres, of 0.05 to 4.5 mm length) were highest in the SML-selective samples (with a mean concentration of 43 ± 36 fibres/L), compared to <5 fibres/L for surface and sub-surface bulk water samples. Data collected show the usefulness of the dipped glass plate method as a rapid and inexpensive tool for sampling SML-associated microplastics in estuaries, and indicate that microplastics preferentially accumulate at the SML in estuarine conditions (providing a potential transfer mechanism for incorporation into upper intertidal sinks). Fibres are present (and readily sampled) in both developed and more pristine estuarine systems.

Candida neustonensis sp. nov., a novel ascomycetous yeast isolated from the sea surface microlayer in Taiwan.

PubMed

Chang, Chin-Feng; Lee, Ching-Fu; Liu, Shiu-Mei

2010-01-01

A new ascomycetous yeast species, Candida neustonensis is proposed in this study based on four strains (SN92(T), SN47, SJ22, SJ25) isolated from sea surface microlayer in Taiwan. These four yeast strains were morphologically, physiologically and phylogenetically identical to each other. No sexual reproduction was observed on 5% malt extract agar, corn meal agar, V8 agar, McClary's acetate agar and potato-dextrose agar. Phylogenetic analysis of the sequences of the D1/D2 domain of the large subunit (LSU) rRNA gene places C. neustonensis as a member of the Pichia guilliermondii clade, it also reveals that the phylogenetically closest relatives of C. neustonensis are C. fukuyamaensis (4.4% divergence), C. xestobii (4.4% divergence) and P. guilliermondii (4.5% divergence). C. neustonensis also is clearly distinguished from other known species in the P. guilliermondii clade based on the results of physiology tests. From these comparison analyses, the following novel yeast species is proposed: Candida neustonensis sp. nov., with strain SN92(T) (= BCRC 23108(T) = JCM 14892(T) = CBS 11061(T)) as the type strain.

Surface microlayer enrichment of polycyclic aromatic hydrocarbons in lower Chesapeake Bay

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, K.; Dickhut, R.M.

1995-12-31

Surface microlayer samples were collected with a rotating cylinder sampler in the York River and Elizabeth River tributaries of lower Chesapeake Bay every other month from May 1994 to June, 1995. Spatial and temporal variabilities were also investigated over an annual cycle as well as shorter periods (i.e. days). All the samples were analyzed for 17 polycyclic aromatic hydrocarbons, total suspended particulate matter (TSP), particular organic carbon (POC), total nitrogen(TN) and dissolved organic carbon (DOC), and selected samples for chlorophyll. TSP in the surface microlayer was 10 to 100 times higher than that in the related bulk water. Particle associatedmore » PAH concentrations were 20--50 times those in bulk surface water, whereas PAH concentrations in freely dissolved phase of the surface microlayer were 5--60 times higher than dissolved concentrations in the bulk water. Particulate PAH concentrations increase with TSP in the surface microlayer and dissolved PAH concentrations increase with DOC. Overall, surface microlayer characteristics were found to be significantly affected by hydrological and meteorological parameters.« less

Sea surface microlayers: A unified physicochemical and biological perspective of the air-ocean interface

NASA Astrophysics Data System (ADS)

Cunliffe, Michael; Engel, Anja; Frka, Sanja; Gašparović, Blaženka; Guitart, Carlos; Murrell, J. Colin; Salter, Matthew; Stolle, Christian; Upstill-Goddard, Robert; Wurl, Oliver

2013-02-01

The sea surface microlayer (SML) covers more than 70% of the Earth's surface and is the boundary layer interface between the ocean and the atmosphere. This important biogeochemical and ecological system is critical to a diverse range of Earth system processes, including the synthesis, transformation and cycling of organic material, and the air-sea exchange of gases, particles and aerosols. In this review we discuss the SML paradigm, taking into account physicochemical and biological characteristics that define SML structure and function. These include enrichments in biogenic molecules such as carbohydrates, lipids and proteinaceous material that contribute to organic carbon cycling, distinct microbial assemblages that participate in air-sea gas exchange, the generation of climate-active aerosols and the accumulation of anthropogenic pollutants with potentially serious implications for the health of the ocean. Characteristically large physical, chemical and biological gradients thus separate the SML from the underlying water and the available evidence implies that the SML retains its integrity over wide ranging environmental conditions. In support of this we present previously unpublished time series data on bacterioneuston composition and SML surfactant activity immediately following physical SML disruption; these imply timescales of the order of minutes for the reestablishment of the SML following disruption. A progressive approach to understanding the SML and hence its role in global biogeochemistry can only be achieved by considering as an integrated whole, all the key components of this complex environment.

High wind speeds prevent formation of a distinct bacterioneuston community in the sea-surface microlayer

PubMed Central

Stolle, Christian; Giebel, Helge-Ansgar; Brinkhoff, Thorsten; Ribas-Ribas, Mariana; Hodapp, Dorothee; Wurl, Oliver

2017-01-01

Abstract The sea-surface microlayer (SML) at the boundary between atmosphere and hydrosphere represents a demanding habitat for bacteria. Wind speed is a crucial but poorly studied factor for its physical integrity. Increasing atmospheric burden of CO2, as suggested for future climate scenarios, may particularly act on this habitat at the air–sea interface. We investigated the effect of increasing wind speeds and different pCO2 levels on SML microbial communities in a wind-wave tunnel, which offered the advantage of low spatial and temporal variability. We found that enrichment of bacteria in the SML occurred solely at a U10 wind speed of ≤5.6 m s−1 in the tunnel and ≤4.1 m s−1 in the Baltic Sea. High pCO2 levels further intensified the bacterial enrichment in the SML during low wind speed. In addition, low wind speed and pCO2 induced the formation of a distinctive bacterial community as revealed by 16S rRNA gene fingerprints and influenced the presence or absence of individual taxonomic units within the SML. We conclude that physical stability of the SML below a system-specific wind speed threshold induces specific bacterial communities in the SML entailing strong implications for ecosystem functioning by wind-driven impacts on habitat properties, gas exchange and matter cycling processes. PMID:28369320

High wind speeds prevent formation of a distinct bacterioneuston community in the sea-surface microlayer.

PubMed

Rahlff, Janina; Stolle, Christian; Giebel, Helge-Ansgar; Brinkhoff, Thorsten; Ribas-Ribas, Mariana; Hodapp, Dorothee; Wurl, Oliver

2017-05-01

The sea-surface microlayer (SML) at the boundary between atmosphere and hydrosphere represents a demanding habitat for bacteria. Wind speed is a crucial but poorly studied factor for its physical integrity. Increasing atmospheric burden of CO2, as suggested for future climate scenarios, may particularly act on this habitat at the air-sea interface. We investigated the effect of increasing wind speeds and different pCO2 levels on SML microbial communities in a wind-wave tunnel, which offered the advantage of low spatial and temporal variability. We found that enrichment of bacteria in the SML occurred solely at a U10 wind speed of ≤5.6 m s-1 in the tunnel and ≤4.1 m s-1 in the Baltic Sea. High pCO2 levels further intensified the bacterial enrichment in the SML during low wind speed. In addition, low wind speed and pCO2 induced the formation of a distinctive bacterial community as revealed by 16S rRNA gene fingerprints and influenced the presence or absence of individual taxonomic units within the SML. We conclude that physical stability of the SML below a system-specific wind speed threshold induces specific bacterial communities in the SML entailing strong implications for ecosystem functioning by wind-driven impacts on habitat properties, gas exchange and matter cycling processes. © FEMS 2017.

The Ocean's Vital Skin: Toward an Integrated Understanding of the Sea Surface Microlayer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Engel, Anja; Bange, Hermann W.; Cunliffe, Michael

Despite the huge extent of the ocean’s surface, until now relatively little attention has been paid to the sea surface microlayer (SML) as the ultimate interface where heat, momentum and mass exchange between the ocean and the atmosphere takes place. Via the SML, large-scale environmental changes in the ocean such as warming, acidification, deoxygenation, and eutrophication potentially influence cloud formation, precipitation, and the global radiation balance. Due to the deep connectivity between biological, chemical, and physical processes, studies of the SML may reveal multiple sensitivities to global and regional changes. Understanding the processes at the ocean’s surface, in particular involvingmore » the SML as an important and determinant interface, could therefore provide an essential contribution to the reduction of uncertainties regarding ocean-climate feedbacks. This review identifies gaps in our current knowledge of the SML and highlights a need to develop a holistic and mechanistic understanding of the diverse biological, chemical, and physical processes occurring at the ocean-atmosphere interface. We advocate the development of strong interdisciplinary expertise and collaboration in order to bridge between ocean and atmospheric sciences. Although this will pose significant methodological challenges, such an initiative would represent a new role model for interdisciplinary research in Earth System sciences.« less

The Ocean's Vital Skin: Toward an Integrated Understanding of the Sea Surface Microlayer

DOE PAGES

Engel, Anja; Bange, Hermann W.; Cunliffe, Michael; ...

2017-05-30

Despite the huge extent of the ocean’s surface, until now relatively little attention has been paid to the sea surface microlayer (SML) as the ultimate interface where heat, momentum and mass exchange between the ocean and the atmosphere takes place. Via the SML, large-scale environmental changes in the ocean such as warming, acidification, deoxygenation, and eutrophication potentially influence cloud formation, precipitation, and the global radiation balance. Due to the deep connectivity between biological, chemical, and physical processes, studies of the SML may reveal multiple sensitivities to global and regional changes. Understanding the processes at the ocean’s surface, in particular involvingmore » the SML as an important and determinant interface, could therefore provide an essential contribution to the reduction of uncertainties regarding ocean-climate feedbacks. This review identifies gaps in our current knowledge of the SML and highlights a need to develop a holistic and mechanistic understanding of the diverse biological, chemical, and physical processes occurring at the ocean-atmosphere interface. We advocate the development of strong interdisciplinary expertise and collaboration in order to bridge between ocean and atmospheric sciences. Although this will pose significant methodological challenges, such an initiative would represent a new role model for interdisciplinary research in Earth System sciences.« less

The role of jet and film drops in controlling the mixing state of submicron sea spray aerosol particles

NASA Astrophysics Data System (ADS)

Wang, Xiaofei; Deane, Grant B.; Moore, Kathryn A.; Ryder, Olivia S.; Stokes, M. Dale; Beall, Charlotte M.; Collins, Douglas B.; Santander, Mitchell V.; Burrows, Susannah M.; Sultana, Camille M.; Prather, Kimberly A.

2017-07-01

The oceans represent a significant global source of atmospheric aerosols. Sea spray aerosol (SSA) particles comprise sea salts and organic species in varying proportions. In addition to size, the overall composition of SSA particles determines how effectively they can form cloud droplets and ice crystals. Thus, understanding the factors controlling SSA composition is critical to predicting aerosol impacts on clouds and climate. It is often assumed that submicrometer SSAs are mainly formed by film drops produced from bursting bubble-cap films, which become enriched with hydrophobic organic species contained within the sea surface microlayer. In contrast, jet drops formed from the base of bursting bubbles are postulated to mainly produce larger supermicrometer particles from bulk seawater, which comprises largely salts and water-soluble organic species. However, here we demonstrate that jet drops produce up to 43% of total submicrometer SSA number concentrations, and that the fraction of SSA produced by jet drops can be modulated by marine biological activity. We show that the chemical composition, organic volume fraction, and ice nucleating ability of submicrometer particles from jet drops differ from those formed from film drops. Thus, the chemical composition of a substantial fraction of submicrometer particles will not be controlled by the composition of the sea surface microlayer, a major assumption in previous studies. This finding has significant ramifications for understanding the factors controlling the mixing state of submicrometer SSA particles and must be taken into consideration when predicting SSA impacts on clouds and climate.

New Photosensitized Processes at Aerosol and Ocean Surfaces

NASA Astrophysics Data System (ADS)

Rossignol, S.; Aregahegn, K. Z.; Ciuraru, R.; Bernard, F.; Tinel, L.; Fine, L.; George, C.

2014-12-01

From a few years now, there is a growing body of evidence that photoinduced processes could be of great importance for the tropospheric chemistry. Here, we would like to present two additional outcomes of this new area of research, firstly the photosensitized direct VOC uptake by aerosols and, secondly, the photoinduced chemical formation of unsaturated VOC from marine microlayer proxy. It was recently shown that the chemistry of glyoxal toward ammonium ions into droplets and wet aerosols leads to the formation of light-absorbing compounds. Among them, we found that imidazole-2-carboxaldehyde (IC) acts as a photosensitizer and is able to initiate the growth of organic aerosols via the uptake of VOC, such as limonene. Given its potential importance, the mechanism of this photoinduced uptake was investigated thanks to aerosol flow tube experiments and UPLC-ESI-HRMS analysis. Results reveal hydrogen abstraction on the VOC molecule by the triplet state of IC leading to the VOC oxidation without any traditional oxidant. As well as aerosol, the sea-surface microlayer, known to be enriched in light-absorbing organics, is largely impacted by photochemical processes. Recent studies have pointed out for example the role of photosentitized processes in the loss of NO2 and ozone at water surfaces containing photoactive compounds such as chlorophyll. In order to go further, we worked from sea-surface microlayer proxy containing humic acids as photoactive material and organic acids as surfactants. Beside oxidation processes, we monitored by high resolution PTR-MS the release in the gas phase of unsaturated compounds, including C5 dienes (isoprene ?). A strong correlation between the measured surface tension and the C5 diene concentration in the gas phase was evidenced, clearly pointing toward an interfacial process. This contribution will highlight the similarities between both systems and will attempt to present a general chemical scheme for photosensitized chemistry at interfaces.

Comparison of solid-phase and pore-water approaches for assessing the quality of marine and estuarine sediments

USGS Publications Warehouse

Carr, Robert Scott; Chapman, Duane C.

1992-01-01

As part of our continuing evaluation of the pore-water approach for assessing sediment quality, we made a series of side-by-side comparisons between the standard 10-day amphipod whole sediment test with the corophiid Grandidierella japonica and a suite of tests using pore water extracted from the same sediments. the pore-water tests evaluated were the sea urchin (Arbacia punctulata) sperm cell test and morphological development assay, the life-cycle test with the polychaete Dinophilus gyrociliatus, and acute exposures of red drum (Sciaenops ocellatus) embryo-larval stages. Sediment and surface microlayer samples were collected from contaminated sites. Whole-sediment, pore-water, and surface microlayer toxicity tests were performed. Pore-water toxicity tests were considerably more sensitive than the whole-sediment amphipod test, which is currently the most sensitive toxicity test now recommended for determining the acceptability of dredged material for open ocean disposal.

Microplastic in two South Carolina Estuaries: Occurrence, distribution, and composition.

PubMed

Gray, Austin D; Wertz, Hope; Leads, Rachel R; Weinstein, John E

2018-03-01

Here we report on the distribution of microplastic contamination in two developed estuaries in the Southeastern United States. Average concentration in intertidal sediments of Charleston Harbor and Winyah Bay, both located in South Carolina, U.S.A., was 413.8 ± 76.7 and 221.0 ± 25.6 particles/m 2 , respectively. Average concentration in the sea surface microlayer of Charleston Harbor and Winyah Bay was 6.6 ± 1.3 and 30.8 ± 12.1 particles/L, respectively. Concentration in intertidal sediments of the two estuaries was not significantly different (p = 0.58), however, Winyah Bay contained significantly more microplastics in the sea surface microlayer (p = 0.02). While microplastic concentration in these estuaries was comparable to that reported for other estuaries worldwide, Charleston Harbor contained a high abundance of black microplastic fragments believed to be tire wear particles. Our research is the first to survey microplastic contamination in Southeastern U.S. estuaries and to provide insight on the nature and extent of contamination in these habitats. Copyright © 2018 Elsevier Ltd. All rights reserved.

The role of jet and film drops in controlling the mixing state of submicron sea spray aerosol particles

PubMed Central

Wang, Xiaofei; Deane, Grant B.; Moore, Kathryn A.; Ryder, Olivia S.; Stokes, M. Dale; Beall, Charlotte M.; Santander, Mitchell V.; Burrows, Susannah M.; Sultana, Camille M.; Prather, Kimberly A.

2017-01-01

The oceans represent a significant global source of atmospheric aerosols. Sea spray aerosol (SSA) particles comprise sea salts and organic species in varying proportions. In addition to size, the overall composition of SSA particles determines how effectively they can form cloud droplets and ice crystals. Thus, understanding the factors controlling SSA composition is critical to predicting aerosol impacts on clouds and climate. It is often assumed that submicrometer SSAs are mainly formed by film drops produced from bursting bubble-cap films, which become enriched with hydrophobic organic species contained within the sea surface microlayer. In contrast, jet drops formed from the base of bursting bubbles are postulated to mainly produce larger supermicrometer particles from bulk seawater, which comprises largely salts and water-soluble organic species. However, here we demonstrate that jet drops produce up to 43% of total submicrometer SSA number concentrations, and that the fraction of SSA produced by jet drops can be modulated by marine biological activity. We show that the chemical composition, organic volume fraction, and ice nucleating ability of submicrometer particles from jet drops differ from those formed from film drops. Thus, the chemical composition of a substantial fraction of submicrometer particles will not be controlled by the composition of the sea surface microlayer, a major assumption in previous studies. This finding has significant ramifications for understanding the factors controlling the mixing state of submicrometer SSA particles and must be taken into consideration when predicting SSA impacts on clouds and climate. PMID:28630346

Transport and distribution of bacteria and diatoms in the aqueous surface micro-layer of a salt marsh

USGS Publications Warehouse

Harvey, Ronald W.; Lion, Leonard W.; Young, Lily Y.

1983-01-01

The effects of tide and wind upon the distribution and transport of bacteria and diatoms in the aqueous surface microlayers of a Massachusetts and San Francisco Bay salt marsh were examined. The compression of the surface films by both tide and wind resulted in significant enrichments of bacterioneuston. At the San Francisco Bay site, significant numbers of diatoms were transported within the microlayer over a tidal cycle.

Geology and surface geochemistry of the Roosevelt Springs Known Geothermal Resource Area, Utah

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lovell, J.S.; Meyer, W.T.; Atkinson, D.J.

1980-01-01

Available data on the Roosevelt area were synthesized to determine the spatial arrangement of the rocks, and the patterns of mass and energy flow within them. The resulting model lead to a new interpretation of the geothermal system, and provided ground truth for evaluating the application of soil geochemistry to exploration for concealed geothermal fields. Preliminary geochemical studies comparing the surface microlayer to conventional soil sampling methods indicated both practical and chemical advantages for the surface microlayer technique, which was particularly evident in the case of As, Sb and Cs. Subsequent multi-element analyses of surface microlayer samples collected over anmore » area of 100 square miles were processed to produce single element contour maps for 41 chemical parameters. Computer manipulation of the multi-element data using R-mode factor analysis provided the optimum method of interpretation of the surface microlayer data. A trace element association of As, Sb and Cs in the surface microlayer provided the best indication of the leakage of geothermal solutions to the surface, while regional mercury trends may reflect the presence of a mercury vapour anomaly above a concealed heat source.« less

Seasonal signatures in SFG vibrational spectra of the sea surface nanolayer at Boknis Eck Time Series Station (SW Baltic Sea)

NASA Astrophysics Data System (ADS)

Laß, K.; Bange, H. W.; Friedrichs, G.

2013-02-01

The very thin sea surface nanolayer on top of the sea surface microlayer, sometimes just one monomolecular layer thick, forms the interface between ocean and atmosphere. Due to the small dimension and tiny amount of substance, knowledge about the development of the layer in the course of the year is scarce. In this work, the sea surface nanolayer at Boknis Eck Time Series Station (BE), southwestern Baltic Sea, has been investigated over a period of three and a half years. Surface water samples were taken monthly by screen sampling and were analyzed in terms of organic content and composition by sum frequency generation spectroscopy, which is specifically sensitive to interfacial layers. A yearly periodicity has been observed with a pronounced abundance of sea surface nanolayer material (such as carbohydrate-rich material) during the summer months. On the basis of our results we conclude that the abundance of organic material in the nanolayer at Boknis Eck is not directly related to phytoplankton abundance. We suggest that indeed sloppy feeding of zooplankton together with photochemical and/or microbial processing of organic precursor compounds are responsible for the pronounced seasonality.

Seasonal signatures in SFG vibrational spectra of the sea surface nanolayer at Boknis Eck Time Series Station (SW Baltic Sea)

NASA Astrophysics Data System (ADS)

Laß, K.; Bange, H. W.; Friedrichs, G.

2013-08-01

The very thin sea surface nanolayer on top of the sea surface microlayer, sometimes just one monomolecular layer thick, forms the interface between ocean and atmosphere. Due to the small dimension and tiny amount of substance, knowledge about the development of the layer in the course of the year is scarce. In this work, the sea surface nanolayer at Boknis Eck Time Series Station (BE), southwestern Baltic Sea, has been investigated over a period of three and a half years. Surface water samples were taken monthly by screen sampling and were analyzed in terms of organic content and composition by sum frequency generation spectroscopy, which is specifically sensitive to interfacial layers. A yearly periodicity has been observed with a pronounced abundance of sea surface nanolayer material (such as carbohydrate-rich material) during the summer months. On the basis of our results we conclude that the abundance of organic material in the nanolayer at Boknis Eck is not directly related to phytoplankton abundance alone. We speculate that indeed sloppy feeding of zooplankton together with photochemical and/or microbial processing of organic precursor compounds is responsible for the pronounced seasonality.

Biopolymers form a gelatinous microlayer at the air-sea interface when Arctic sea ice melts

PubMed Central

Galgani, Luisa; Piontek, Judith; Engel, Anja

2016-01-01

The interface layer between ocean and atmosphere is only a couple of micrometers thick but plays a critical role in climate relevant processes, including the air-sea exchange of gas and heat and the emission of primary organic aerosols (POA). Recent findings suggest that low-level cloud formation above the Arctic Ocean may be linked to organic polymers produced by marine microorganisms. Sea ice harbors high amounts of polymeric substances that are produced by cells growing within the sea-ice brine. Here, we report from a research cruise to the central Arctic Ocean in 2012. Our study shows that microbial polymers accumulate at the air-sea interface when the sea ice melts. Proteinaceous compounds represented the major fraction of polymers supporting the formation of a gelatinous interface microlayer and providing a hitherto unrecognized potential source of marine POA. Our study indicates a novel link between sea ice-ocean and atmosphere that may be sensitive to climate change. PMID:27435531

Distribution and Identification of Luminous Bacteria from the Sargasso Sea

PubMed Central

Orndorff, S. A.; Colwell, R. R.

1980-01-01

Vibrio fischeri and Lucibacterium harveyi constituted 75 of the 83 luminous bacteria isolated from Sargasso Sea surface waters. Photobacterium leiognathi and Photobacterium phosphoreum constituted the remainder of the isolates. Luminescent bacteria were recovered at concentrations of 1 to 63 cells per 100 ml from water samples collected at depths of 160 to 320 m. Two water samples collected at the thermocline yielded larger numbers of viable, aerobic heterotrophic and luminous bacteria. Luminescent bacteria were not recovered from surface microlayer samples. The species distribution of the luminous bacteria reflected previously recognized growth patterns; i.e., L. harveyi and V. fischeri were predominant in the upper, warm waters (only one isolate of P. phosphoreum was obtained from surface tropical waters). PMID:16345575

Occurrence and distribution of hydrocarbons in the surface microlayer and subsurface water from the urban coastal marine area off Marseilles, Northwestern Mediterranean Sea.

PubMed

Guigue, Catherine; Tedetti, Marc; Giorgi, Sébastien; Goutx, Madeleine

2011-12-01

Aliphatic (AHs) and polycyclic aromatic hydrocarbons (PAHs) were analyzed in dissolved and particulate material from surface microlayer (SML) and subsurface water (SSW) sampled at nearshore observation stations, sewage effluents and harbour sites from Marseilles coastal area (Northwestern Mediterranean) in 2009 and 2010. Dissolved and particulate AH concentrations ranged 0.05-0.41 and 0.04-4.3 μg l(-1) in the SSW, peaking up to 38 and 1366 μg l(-1) in the SML, respectively. Dissolved and particulate PAHs ranged 1.9-98 and 1.9-21 ng l(-1) in the SSW, amounting up 217 and 1597 ng l(-1) in the SML, respectively. In harbours, hydrocarbons were concentrated in the SML, with enrichment factors reaching 1138 for particulate AHs. Besides episodic dominance of biogenic and pyrogenic inputs, a moderate anthropisation from petrogenic sources dominated suggesting the impact of shipping traffic and surface runoffs on this urbanised area. Rainfalls increased hydrocarbon concentrations by a factor 1.9-11.5 in the dissolved phase. Copyright © 2011 Elsevier Ltd. All rights reserved.

Biological and Chemical Significance of Surface Microlayers in Aquatic Ecosystems

ERIC Educational Resources Information Center

Parker, B.; Barsom, G.

1970-01-01

Reviews methods of study, chemical composition, physical properties and ecology of surface microlayers in marine and fresh water habitats. Relates to problems of air and water pollution. Suggests areas for further research. (EB)

Gas and aerosol fluxes. [emphasizing sulfur, nitrogen, and carbon

NASA Technical Reports Server (NTRS)

Martens, C. S.

1980-01-01

The development of remote sensing techniques to address the global need for accurate distribution and flux determinations of both man made and natural materials which affect the chemical composition of the atmosphere, the heat budget of the Earth, and the depletion, of stratospheric ozone is considered. Specifically, trace gas fluxes, sea salt aerosol production, and the effect of sea surface microlayer on gas and aerosol fluxes are examined. Volatile sulfur, carbon, nitrogen, and halocarbon compounds are discussed including a statement of the problem associated with each compound or group of compounds, a brief summary of current understanding, and suggestions for needed research.

Sources of fatty acids in Lake Michigan surface microlayers and subsurface waters

NASA Astrophysics Data System (ADS)

Meyers, Philip A.; Owen, Robert M.

1980-11-01

Fatty acid and organic carbon contents have been measured in the particulate and dissolved phases of surface microlayer and subsurface water samples collected from Lake Michigan. Concentrations are highest close to fluvial sources and lowest in offshore areas, yet surface/subsurface fractionation is lowest near river mouths and highest in open lake locations. These gradients plus accompanying fatty acid compositional changes indicate that river-borne organic materials are important constituents of coastal Lake Michigan microlayers and that sinking and turbulent resuspension of particulates affect surface film characteristics. Lake neuston and plankton contribute organic components which partially replace potamic materials removed by sinking.

Distributions of dissolved monosaccharides and polysaccharides in the surface microlayer and surface water of the Jiaozhou Bay and its adjacent area

NASA Astrophysics Data System (ADS)

Zhang, Yan-Ping; Yang, Gui-Peng; Lu, Xiao-Lan; Ding, Hai-Bing; Zhang, Hong-Hai

2013-07-01

Sea surface microlayer (SML) samples and corresponding bulk surface water (SW) samples were collected in the Jiaozhou Bay and its adjacent area in July and November 2008. The average concentrations of dissolved monosaccharides (MCHO) and polysaccharides (PCHO) revealed similar temporal variability, with higher concentrations during the green-tide period (in July) than during the non-green-tide period (in November). Average enrichment factors (EF) of MCHO and PCHO, defined as the ratio of the concentration in the SML to that in the SW, were 1.3 and 1.4 in July, respectively, while those values in November were 1.9 and 1.6. Our data also showed that the concentrations of MCHO and PCHO in the SML were strongly correlated with those in the SW, indicating that most of the organic materials in the SML came from the SW. The total dissolved carbohydrate concentrations (TDCHO) in the bulk surface water were closely correlated with salinity during the cruises (July: r=-0.580, n=18, P=0.01; November: r=-0.679, n=26, P<0.001), suggesting that riverine input had an important effect on the distribution of TDCHO in surface seawater of the study area.

Enzymatic activity in the surface microlayer and subsurface water in the harbour channel

NASA Astrophysics Data System (ADS)

Perliński, Piotr; Mudryk, Zbigniew J.; Antonowicz, Józef

2017-09-01

Hydrolytic activity of eight extracellular enzymes was determined spectrofluorimetric method in the surface microlayer and subsurface water in the harbour channel in Ustka. The ranking order of the potential enzyme activity rates in the studied water layers was as follows: lipase > phosphatase > aminopeptidase > β-glucosidase > α-glucosidase > xylanase > cellulase > chitinase. The level of activity of all studied hydrolases was higher in the surface microlayer than subsurface water. No clear gradients in the level of enzymatic activity were determined along the horizontal profile of the studied channel. Activity of extracellular enzymes was strongly influenced by the season.

Research and Logistical Support for the Office of Naval Research Accelerated Research Initiative on Marine Microlayer Processes

DTIC Science & Technology

1991-12-13

1962)] Broekmann et al. 11980111 Petermann [ 197/61, Oleophilic pollutant accumula- Hartung and Klinger 11970]" .. 7 tion Seba and Corcoran 11969...wave tanks by using different organic Petermann , and G. Hent schel, Artificial surface films in the sea chemical films, wave-wave interactions must be...Phys. Oceanogr., 8, 142-150, Petermann , I.. Der Einfluss der 6brflichenspannung wssnger Sys-!l1977. teme auf die Kinetik der Gasabsorption

Diversity of yeasts associated with the sea surface microlayer and underlying water along the northern coast of Taiwan.

PubMed

Chang, Chin-Feng; Lee, Ching-Fu; Lin, Kao-Yung; Liu, Shiu-Mei

2016-01-01

Yeast communities inhabiting the sea surface microlayer (SSML) on the northern coast of Taiwan were examined using a cultivation method and compared with those inhabiting the underlying water (UW) at a 50-cm depth. Culturable yeasts were recovered from the SSML and UW samples collected in the morning during 4 field campaigns, and 420 strains were isolated. The 420 isolates were grouped into 43 species using a polyphasic molecular approach, including sequence analysis of the 26S rDNA D1/D2 domain and 5.8S-ITS region. From the SSML samples, 12 genera and 39 species, including 7 new species of Cryptococcus sp. (1), Candida spp. (4), and Rhodotorula spp. (2), were isolated. From the UW samples, 10 genera and 21 species, including one new species of Rhodotorula sp. (1), were isolated. Rhodotorula mucilaginosa was the most abundant species present in the yeast community in SSML (37.6%) and UW (21.6%) samples. Basidiomycetous yeasts (63.6%) and pigmented yeasts (64.5%) comprised the major yeast population. The yeast community in the SSML had a higher species number and abundance than the UW. Moreover, although the majority of yeast community species were from the SSML, individual species distribution in the SSML was unequal. Copyright © 2015 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Air--sea gaseous exchange of PCB at the Venice lagoon (Italy).

PubMed

Manodori, L; Gambaro, A; Moret, I; Capodaglio, G; Cescon, P

2007-10-01

Water bodies are important storage media for persistent organic pollutants (POPs) such as polychlorinated biphenyls (PCBs) and this function is increased in coastal regions because their inputs are higher than those to the open sea. The air-water interface is extensively involved with the global cycling of PCBs because it is the place where they accumulate due to depositional processes and where they may be emitted by gaseous exchange. In this work the parallel collection of air, microlayer and sub-superficial water samples was performed in July 2005 at a site in the Venice lagoon to evaluate the summer gaseous flux of PCBs. The total concentration of PCBs (sum of 118 congeners) in air varies from 87 to 273 pg m(-3), whereas in the operationally defined dissolved phase of microlayer and sub-superficial water samples it varies from 159 to 391 pg L(-1). No significant enrichment of dissolved PCB into the microlayer has been observed, although a preferential accumulation of most hydrophobic congeners occurs. Due to this behaviour, we believe that the modified two-layer model was the most suitable approach for the evaluation of the flux at the air-sea interface, because it takes into account the influence of the microlayer. From its application it appears that PCB volatilize from the lagoon waters with a net flux varying from 58 to 195 ng m(-2)d(-1) (uncertainty: +/-50-64%) due to the strong influence of wind speed. This flux is greater than those reported in the literature for the atmospheric deposition and rivers input and reveals that PCB are actively emitted from the Venice lagoon in summer months.

Changes in optical characteristics of surface microlayers in the Peruvian upwelling region hint to photochemically and microbially-mediated DOM turnover

NASA Astrophysics Data System (ADS)

Engel, A.; Galgani, L.

2016-02-01

The coastal upwelling system off Peru is characterized by high biological activity and associated subsurface oxygen minimum zone, leading to an enhanced emission of atmospheric trace gases. High biological productivity in the water column may promote the establishment of enriched organic surface films, key environments for processes regulating gas fluxes across the water-air interface. During M91 cruise to the Peruvian upwelling, we focused our attention on the composition of the sea-surface microlayer (SML), the oceanic uppermost boundary directly subject to high solar radiation, often enriched in specific organic compounds of biological origin like Chromophoric Dissolved Organic Matter (CDOM) and marine gels. In the SML, the continuous photochemical and microbial recycling of organic matter may strongly influence gas exchange between marine systems and the atmosphere. In order to understand organic matter cycling in surface films, we analyzed SML and underlying water samples in 38 stations determining DOC concentrations, amino acids composition, marine gels, CDOM and bacterial abundance as indicators of photochemical and microbial alteration processes. CDOM composition was characterized by spectral slopes (S) values and Excitation-Emission Matrix fluorescence (EEMs), which allow to track changes in molecular weight (MW) of DOM, and to determine potential DOM sources. Profound changes in spectral slope properties were observed suggesting smaller MW CDOM in the SML compared to underlying water. Microbial and photochemical degradation are likely the main drivers for organic matter cycling in the top layer of the ocean. Consequences on the formation of inorganic and organic species highly relevant for air-sea gas exchange and for climate dynamics will be discussed.

Study on organic matter fractions in the surface microlayer in the Baltic Sea by spectrophotometric and spectrofluorometric methods

NASA Astrophysics Data System (ADS)

Drozdowska, Violetta; Wrobel, Iwona; Markuszewski, Piotr; Makuch, Przemysław; Raczkowska, Anna; Kowalczuk, Piotr

2017-08-01

The fluorescence and absorption measurements of the samples collected from a surface microlayer (SML) and a subsurface layer (SS), at a depth of 1 m, were studied during three research cruises in the Baltic Sea along with hydrophysical studies and meteorological observations. Several absorption (E2 : E3, S, SR) and fluorescence (fluorescence intensities at Coble classified peaks: A, C, M, T the ratio M + T/A + C, HIX (humification index)) indices of colored and fluorescent dissolved organic matter (CDOM and FDOM) helped to describe the changes in molecular size and weight as well as in composition of organic matter. The investigation allowed the assessment of a decrease in the contribution of two terrestrial components (A and C) with increasing salinity ( ˜ 1.64 and ˜ 1.89 % in the SML and ˜ 0.78 and ˜ 0.71 % in the SS, respectively) and an increase in components produced in situ (M and T) with salinity ( ˜ 0.52 and ˜ 2.83 % in the SML and ˜ 0.98 and ˜ 1.87 % in the SS, respectively). Hence, a component T reveals the biggest relative changes along the transect from the Vistula River outlet to Gdansk Deep, in both the SML and SS, although an increase was higher in the SML than in the SS ( ˜ 18.5 and ˜ 12.3 %, respectively). The ratio E2 : E3 points to greater changes in the molecular weight of CDOM affected by a higher rate of photobleaching in the SML. The HIX index reflects a more advanced stage of humification and condensation processes in the SS. Finally, the results reveal a higher rate of degradation processes occurring in the SML than in the SS. Thus, the specific physical properties of surface active organic molecules (surfactants) may modify, in a specific way, the solar light spectrum entering the sea and a penetration depth of the solar radiation. Research on the influence of surfactants on the physical processes linked to the sea surface becomes an important task, especially in coastal waters and in the vicinity of the river mouths.

Biofilm-like properties of the sea surface and predicted effects on air-sea CO2 exchange

NASA Astrophysics Data System (ADS)

Wurl, Oliver; Stolle, Christian; Van Thuoc, Chu; The Thu, Pham; Mari, Xavier

2016-05-01

Because the sea surface controls various interactions between the ocean and the atmosphere, it has a profound function for marine biogeochemistry and climate regulation. The sea surface is the gateway for the exchange of climate-relevant gases, heat and particles. Thus, in order to determine how the ocean and the atmosphere interact and respond to environmental changes on a global scale, the characterization and understanding of the sea surface are essential. The uppermost part of the water column is defined as the sea-surface microlayer and experiences strong spatial and temporal dynamics, mainly due to meteorological forcing. Wave-damped areas at the sea surface are caused by the accumulation of surface-active organic material and are defined as slicks. Natural slicks are observed frequently but their biogeochemical properties are poorly understood. In the present study, we found up to 40 times more transparent exopolymer particles (TEP), the foundation of any biofilm, in slicks compared to the underlying bulk water at multiple stations in the North Pacific, South China Sea, and Baltic Sea. We found a significant lower enrichment of TEP (up to 6) in non-slick sea surfaces compared to its underlying bulk water. Moreover, slicks were characterized by a large microbial biomass, another shared feature with conventional biofilms on solid surfaces. Compared to non-slick samples (avg. pairwise similarity of 70%), the community composition of bacteria in slicks was increasingly (avg. pairwise similarity of 45%) different from bulk water communities, indicating that the TEP-matrix creates specific environments for its inhabitants. We, therefore, conclude that slicks can feature biofilm-like properties with the excessive accumulation of particles and microbes. We also assessed the potential distribution and frequency of slick-formation in coastal and oceanic regions, and their effect on air-sea CO2 exchange based on literature data. We estimate that slicks can reduce CO2 fluxes by up to 15%, and, therefore, play important local and regional roles in regulating air-sea interactions.

Variations of the Organic Matter Composition in the Sea Surface Microlayer: A Comparison between Open Ocean, Coastal, and Upwelling Sites Off the Peruvian Coast

PubMed Central

Zäncker, Birthe; Bracher, Astrid; Röttgers, Rüdiger; Engel, Anja

2017-01-01

The sea surface microlayer (SML) is the thin boundary layer between the ocean and the atmosphere, making it important for air-sea exchange processes. However, little is known about what controls organic matter composition in the SML. In particular, there are only few studies available on the differences of the SML of various oceanic systems. Here, we compared the organic matter and neuston species composition in the SML and the underlying water (ULW) at 11 stations with varying distance from the coast in the Peruvian upwelling regime, a system with high emissions of climate relevant trace gases, such as N2O and CO2. In the open ocean, organic carbon, and amino acids were highly enriched in the SML compared to the ULW. The enrichment decreased at the coastal stations and vanished in the upwelling regime. At the same time, the degradation of organic matter increased from the open ocean to the upwelling stations. This suggests that in the open ocean, upward transport processes or new production of organic matter within the SML are faster than degradation processes. Phytoplankton was generally not enriched in the SML, one group though, the Trichodesmium-like TrL (possibly containing Trichodesmium), were enriched in the open ocean but not in the upwelling region indicating that they find a favorable habitat in the open ocean SML. Our data show that the SML is a distinct habitat; its composition is more similar among different systems than between SML and ULW of a single station. Generally the enrichment of organic matter is assumed to be reduced when encountering low primary production and high wind speeds. However, our study shows the highest enrichments of organic matter in the open ocean which had the lowest primary production and the highest wind speeds. PMID:29375483

Variations of the Organic Matter Composition in the Sea Surface Microlayer: A Comparison between Open Ocean, Coastal, and Upwelling Sites Off the Peruvian Coast.

PubMed

Zäncker, Birthe; Bracher, Astrid; Röttgers, Rüdiger; Engel, Anja

2017-01-01

The sea surface microlayer (SML) is the thin boundary layer between the ocean and the atmosphere, making it important for air-sea exchange processes. However, little is known about what controls organic matter composition in the SML. In particular, there are only few studies available on the differences of the SML of various oceanic systems. Here, we compared the organic matter and neuston species composition in the SML and the underlying water (ULW) at 11 stations with varying distance from the coast in the Peruvian upwelling regime, a system with high emissions of climate relevant trace gases, such as N 2 O and CO 2 . In the open ocean, organic carbon, and amino acids were highly enriched in the SML compared to the ULW. The enrichment decreased at the coastal stations and vanished in the upwelling regime. At the same time, the degradation of organic matter increased from the open ocean to the upwelling stations. This suggests that in the open ocean, upward transport processes or new production of organic matter within the SML are faster than degradation processes. Phytoplankton was generally not enriched in the SML, one group though, the Trichodesmium -like TrL (possibly containing Trichodesmium ), were enriched in the open ocean but not in the upwelling region indicating that they find a favorable habitat in the open ocean SML. Our data show that the SML is a distinct habitat; its composition is more similar among different systems than between SML and ULW of a single station. Generally the enrichment of organic matter is assumed to be reduced when encountering low primary production and high wind speeds. However, our study shows the highest enrichments of organic matter in the open ocean which had the lowest primary production and the highest wind speeds.

Modeling of Vapor Bubble Growth Under Nucleate Boiling Conditions in Reduced Gravity

NASA Technical Reports Server (NTRS)

Buyevich, Yu A.; Webbon, Bruce W.

1995-01-01

A dynamic model is developed to describe the evolution of a vapor bubble growing at a nucleation site on a superheated surface under arbitrary gravity. The bubble is separated from the surface by a thin microlayer and grows due to the evaporation from the microlayer interface. The average thickness of the microlayer increases as the bubble expands along the surface if the evaporation rate is lower than some critical value. The corresponding threshold value of the surface temperature has to be associated with the burn-out crisis. Two main reasons make for bubble separation, which are the buoyancy force and a force caused by the vapor momentum that comes to the bubble with vapor molecules. The latter force is somewhat diminished if condensation takes place at the upper bubble surface in subcooled liquids. The action of the said forces is opposed by inertia of the additional mass of liquid as the bubble center rises above the surface and by inertia of liquid being expelled by the growing bubble in radial directions. An extra pressure force arises due to the liquid inflow into the microlayer with a finite velocity. The last force helps in holding the bubble close to the surface during an initial stage of bubble evolution. Two limiting regimes with distinctly different properties can be singled out, depending on which of the forces that favor bubble detachment dominates. Under conditions of moderately reduced gravity, the situation is much the same as in normal gravity, although the bubble detachment volume increases as gravity diminishes. In microgravity, the buoyancy force is negligible. Then the bubble is capable of staying near the surface for a long time, with intensive evaporation from the microlayer. It suggests a drastic change in the physical mechanism of heat removal as gravity falls below a certain sufficiently low level. Inferences of the model and conclusions pertaining to effects caused on heat transfer processes by changes in bubble hydrodynamics induced by gravity are discussed in connection with experimental evidence, both available in current and in as yet unpublished literature.

The impact of marine surface organic enrichment on the measured hygroscopicity parameter of laboratory generated sea-spray aerosols

NASA Astrophysics Data System (ADS)

Schill, S.; Novak, G.; Zimmermann, K.; Bertram, T. H.

2014-12-01

The ocean serves as a major source for atmospheric aerosol particles, yet the chemicophysical properties of sea spray aerosol to date are not well characterized. Understanding the transfer of organic compounds, present in the sea surface microlayer (SSML), to sea-spray particles and their resulting impact on cloud formation is important for predicting aerosol impact on climate in remote marine environments. Here, we present a series of laboratory experiments designed to probe the fractionation of select organic molecules during wave breaking. We use a representative set of organic mimics (e.g. sterols, sugars, lipids, proteins, fatty acids) to test a recent physically based model of organic enrichment in sea-spray aerosol [Burrows et al., 2014] that is based on Langmuir absorption equilibria. Experiments were conducted in the UCSD Marine Aerosol Reference Tank (MART) permitting accurate representation of wave breaking processes in the laboratory. We report kappa values for the resulting sea-spray aerosols and compare them to a predictions made using Kappa-Köhler Theory driven by a linear combination of the pure component kappa values. Hygroscopicity determinations made using the model systems are discussed within the context of measurements of CCN activity made using natural, coastal water.

Exopolymer Particles in the Sea Surface Microlayer (SML) of the Coastal Pacific Ocean

NASA Astrophysics Data System (ADS)

Thornton, D. C.; Brooks, S. D.; Chen, J.

2015-12-01

Exchanges of matter and energy between the ocean and atmosphere occur through the sea surface microlayer (SML). The SML is biogeochemically distinct from the underlying water and overlying atmosphere in terms of physical environment, chemical composition, and biological community. We sampled the Pacific Ocean in coastal waters off the state of Oregon (United States) along a seaward transect out from the mouth of the Columbia River (3 stations) and in deeper waters beyond the shelf break (2 stations) in July 2011. SML samples were collected using the glass plate method and the underlying water was sampled using a peristaltic pump from 1, 5 and 10 m depth. The samples were analyzed for carbohydrates and exopolymer particles. Carbohydrates were significantly enriched in the SML compared with the underlying water. The concentration of polysaccharides was higher than monosaccharides at all depths. We enumerated two classes of exopolymer particles: transparent exopolymer particles (TEP) and Coomassie staining particles (CSP). TEP are composed of acid polysaccharides and CSP are formed from proteins. While TEP have been widely studied, CSP are generally overlooked, despite the biogeochemical significance of proteins. Our data showed that TEP and CSP concentrations were enriched in the SML compared with the underlying waters in most cases. The ubiquitous presence of empty diatom frustules in the samples indicates that the collapse of a diatom bloom was the source of the exopolymers. Further, we conducted image analysis of particle size and abundance, which indicated that TEP and CSP are not the same particles and form distinct populations in the ocean. Our data confirm recent observations indicating that TEP are an important component of the SML. In addition, these data show that CSP are also important components of the SML.

Surface microlayer enrichment of volatile organic compounds and semi-volatile organic compounds in drinking water source.

PubMed

Huang, Zhi; Zhou, Wen; Yu, Ya-juan; Zhang, Ai-qian; Han, Shuo-kui; Wang, Lian-sheng

2004-01-01

Enrichment of volatile organic compounds(VOC) and semi-volatility organic compounds(SVOC) in surface microlayer(SM) of three drinking water sources were studied. The enrichment factor(EFs) were 0.67 to 13.37 and 0.16 to 136, respectively. The results showed some VOC and most SVOC could enrich in SM. Some EFs of SVOC was quite high. Suspension and temperature could affect EFs of SVOC, slim wind and water movement do not destroy enrichment of organic in SM.

Atmospheric Aerosol Emissions Related to the Mediterranean Seawater Biogeochemistry

NASA Astrophysics Data System (ADS)

Sellegri, K.; Schwier, A.; Rose, C.; Gazeau, F. P. H.; Guieu, C.; D'anna, B.; Ebling, A. M.; Pey, J.; Marchand, N.; Charriere, B.; Sempéré, R.; Mas, S.

2016-02-01

Marine aerosols contribute significantly to the global aerosol load and consequently has an important impact on the Earth's climate. Different factors influence the way they are produced at the air/seawater interface. The sea state (whitecap coverage, temperature, etc. ) influence the size and concentration of primarily produced particles but also biogeochemical characteristics of the seawater influence both the physical and chemical primary fluxes to the atmosphere. An additional aerosol source of marine aerosol to the atmosphere is the formation of new particles by gaz-to-particle conversion, i.e. nucleation. How the seawater and surface microlayer biogeochemical compositions influences the aerosol emissions is still a large debate. In order to study marine emissions, one approach is to use semi-controlled environments such as mesocosms. Within the MedSea and SAM projects, we characterize the primary Sea Spray Aerosol (SSA) during mesocosms experiments performed during different seasons in the Mediteranean Sea. Mesocosms were either left unchanged as control or enriched by addition of nutriments in order to create different levels of phytoplanctonic activities. The mesocosms waters were daily analyzed for their chemical and biological composition (DOC, CDOM, TEP, Chl-a, virus, bacteria, phytoplankton and zooplankton concentrations). SSA production by bubble bursting was daily simulated in a dedicated set-up. The size segregated SSA number fluxes, cloud condensation nuclei (CCN) properties, and chemical composition were determined as a function of the seawater characteristics. We show that the SSA organic content was clearly correlated to the seawater Chl-a level, provided that the mesocosm was not enriched to create an artificial phytoplanctonic bloom. In our experiments, the enrichment of the seawater with natural surface microlayer did not impact the SSA organic content nor its CCN properties. At last, nucleation of secondary particles were observed to occur in the mesocosm headspace, without any connection to DMS emissions. The occurrence of nucleation of new particles in the open ocean atmosphere is still debated and these findings will be discussed in regard to observations performed in the ambient Mediterranean atmosphere during the MISTRAL/Charmex project.

Radon daughter disequilibria and lead systematics in the western North Atlantic

NASA Astrophysics Data System (ADS)

Hussain, N.; Church, T. M.; VéRon, Alain J.; Larson, R. E.

1998-01-01

Concentrations of 222Rn and 210Pb were measured in the North Atlantic troposphere in 1989 between April 12 and 28, during the Sulfide Experiment (SEX) Cruise I, and those of 222Rn, 210Pb and 210Po, between October 24 and November 9, during the SEX Cruise II. Concentrations of 210Pb and 210Po were also measured in the rain water, surface seawater, and marine microlayer collected during the SEX Cruise II Other data used and published previously include stable lead and its isotopes [Vèron et al., 1992, 1993] on parallel samples. Low 222Rn contents, of the order of 0.1 and 0.3 Bq m-3, were found in the marine air, while continental air showed nearly 10 times higher concentrations of 222Rn. These results corroborate with the air mass trajectory analyses and continental signatures of stable lead isotopes. Significant correlation is found between 222Rn and 210Pb on the aerosol, indicative of excess continental 222Rn supporting the ingrowth of 210Pb from the atmosphere, in spite of its first-order removal by precipitation. Correlation between 210Pb and stable Pb on the aerosol and in the precipitation document the source of pollutant lead from the continental surface. Mean residence times of marine aerosol based on 210Pb is estimated to be 5.4±1.8 days during the April cruise and 19.7±1.9 days during the October cause. Corresponding deposition velocity for 210Pb is estimated to be 1.9±1.9 cm s-1, a value that suggests the dominant role of precipitation scavenging, or aerosol scavenging by larger host phases such as dust or sea salt. Excess 210Po activities are found on the aerosol relative to what would be expected based on 210Pb and the aerosol residence times. In surface seawaters, deficiencies of 210Po are observed. Mechanisms of 210Po enrichment in atmospheric aerosol may include enrichments from the organic components of marine microlayer, sea-salt aerosol, dust, or air-sea exchange of volatile organo-polonium species.

Evolution of Vapor Bubbles Nucleation Sites in Low Gravity

NASA Technical Reports Server (NTRS)

Buyevich, Yu A.; Webbon, Bruce W.

1995-01-01

When liquid is expelled by a vapor bubble growing at a nucleation site on a superheated surface, a thin microlayer underneath the bubble is left behind. It is evaporated from the free microlayer surface that provides for bubble growth. The average thickness of the microlayer determining the evaporation rate increases with time if the latter does not exceed a threshold value associated with the burn-out crisis. The bubble is described as a spherical segment with its flattened part adjoining the microlayer. This introduces two independent variables - the radius of the spherical part of the bubble surface and the polar angle that defines the relative area of the flattened part. They are to be found out from a set of two strongly nonlinear equations resulting from mass and momentum conservation laws. The first one depends on both microlayer thickness and nonmonotonously changing bubble base area. The second involves two major factors favoring bubble detachment - the buoyancy and a force due to the initial momentum of vapor input into the bubble. The former force depends on gravity whereas the latter one does not. It is why the limiting regimes of bubble evolution that correspond to normal or moderately reduced gravity and to microgravity feature drastically different properties. In the first case, the buoyancy dominates and the bubble evolves in such a manner as to become a full sphere at a moment that can be viewed as that of detachment. The detachment volume grows as gravity decreases. In the second case, the buoyancy is negligible and the bubble stays near the surface, while its volume continues to increase for a sufficiently long time. The findings are discussed in connection with experimental data obtained under different gravity conditions, some unpublished experiments being included. They help to understand why the pool boiling heat transfer coefficient frequently increases as gravity falls down and eventually vanishes.

Air-Sea exchange of biogenic volatile organic compounds and the impact on aerosol particle size distributions

NASA Astrophysics Data System (ADS)

Kim, Michelle J.; Novak, Gordon A.; Zoerb, Matthew C.; Yang, Mingxi; Blomquist, Byron W.; Huebert, Barry J.; Cappa, Christopher D.; Bertram, Timothy H.

2017-04-01

We report simultaneous, underway eddy covariance measurements of the vertical flux of isoprene, total monoterpenes, and dimethyl sulfide (DMS) over the Northern Atlantic Ocean during fall. Mean isoprene and monoterpene sea-to-air vertical fluxes were significantly lower than mean DMS fluxes. While rare, intense monoterpene sea-to-air fluxes were observed, coincident with elevated monoterpene mixing ratios. A statistically significant correlation between isoprene vertical flux and short wave radiation was not observed, suggesting that photochemical processes in the surface microlayer did not enhance isoprene emissions in this study region. Calculations of secondary organic aerosol production rates (PSOA) for mean isoprene and monoterpene emission rates sampled here indicate that PSOA is on average <0.1 μg m-3 d-1. Despite modest PSOA, low particle number concentrations permit a sizable role for condensational growth of monoterpene oxidation products in altering particle size distributions and the concentration of cloud condensation nuclei during episodic monoterpene emission events from the ocean.

Mechanisms for trace metal enrichment at the surface microlayer in an estuarine salt marsh

USGS Publications Warehouse

Lion, Leonard W.

1982-01-01

The relative contributions of adsorption to particulate surfaces, complexation with surface-active organic ligands and uptake by micro-organisms were evaluated with respect to their importance in the surface microlayer enrichment (‘partitioning’) of Cd, Pb and Cu. The contributions of each process were inferred from field data in which partitioning of the dissolved and particulate forms of Cd, Pb and Cu, total and dissolved organic carbon, particles and total bacteria were observed. In the South San Francisco Bay estuary, particle enrichment appears to control trace metal partitioning. Trace metal association with the particulate phase and the levels of partitioning observed were in the order Pb > Cu > Cd and reflect the calculated equilibrium chemical speciation of these metals in computer-simulated seawater matrices.

The role of jet and film drops in controlling the mixing state of submicron sea spray aerosol particles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Xiaofei; Deane, Grant B.; Moore, Kathryn A.

Covering 71% of the Earth’s surface, oceans represent a significant global source of atmospheric aerosols. The size and composition of sea spray aerosols (SSA) affect their ability to serve as cloud seeds and thus understanding the factors controlling their composition is critical to predicting their impact on clouds and climate. SSA particles have been shown to be an external mixture of particles with different compositions. Film and jet drop production mechanisms ultimately determine the individual particle compositions which are comprised of an array of salt/organic mixtures ranging from pure sea salt to nearly pure organic particles. It is often assumedmore » that the majority of submicron SSA are formed by film drops produced from bursting hydrophobic organic-rich bubble film caps at the sea surface, and in contrast, jet drops are postulated to produce larger supermicron particles from underlying seawater comprised largely of salts and water soluble organic species. However, here we show that jet drops produced by bursting sub-100 m bubbles account for up to 40 % of all submicron particles. They have distinct chemical compositions, organic volume fractions and ice nucleating activities from submicron film drops. Thus a substantial fraction of submicron particles will not necessarily be controlled by the composition of the sea surface microlayer as has been assumed in many studies. This finding has significant ramifications for the size-resolved mixing states of SSA particles which must be taken into consideration when accessing SSA impacts on clouds.« less

The role of jet and film drops in controlling the mixing state of submicron sea spray aerosol particles

DOE PAGES

Wang, Xiaofei; Deane, Grant B.; Moore, Kathryn A.; ...

2017-06-19

Covering 71% of the Earth’s surface, oceans represent a significant global source of atmospheric aerosols. The size and composition of sea spray aerosols (SSA) affect their ability to serve as cloud seeds and thus understanding the factors controlling their composition is critical to predicting their impact on clouds and climate. SSA particles have been shown to be an external mixture of particles with different compositions. Film and jet drop production mechanisms ultimately determine the individual particle compositions which are comprised of an array of salt/organic mixtures ranging from pure sea salt to nearly pure organic particles. It is often assumedmore » that the majority of submicron SSA are formed by film drops produced from bursting hydrophobic organic-rich bubble film caps at the sea surface, and in contrast, jet drops are postulated to produce larger supermicron particles from underlying seawater comprised largely of salts and water soluble organic species. However, here we show that jet drops produced by bursting sub-100 m bubbles account for up to 40 % of all submicron particles. They have distinct chemical compositions, organic volume fractions and ice nucleating activities from submicron film drops. Thus a substantial fraction of submicron particles will not necessarily be controlled by the composition of the sea surface microlayer as has been assumed in many studies. This finding has significant ramifications for the size-resolved mixing states of SSA particles which must be taken into consideration when accessing SSA impacts on clouds.« less

Changes in optical characteristics of surface microlayers hint to photochemically and microbially-mediated DOM turnover in the upwelling region off Peru

NASA Astrophysics Data System (ADS)

Galgani, L.; Engel, A.

2015-12-01

The coastal upwelling system off Peru is characterized by high biological activity and a pronounced subsurface oxygen minimum zone, as well as associated emissions of atmospheric trace gases such as N2O, CH4 and CO2. During the Meteor (M91) cruise to the Peruvian upwelling system in 2012, we investigated the composition of the sea-surface microlayer (SML), the oceanic uppermost boundary directly subject to high solar radiation, often enriched in specific organic compounds of biological origin like Chromophoric Dissolved Organic Matter (CDOM) and marine gels. In the SML, the continuous photochemical and microbial recycling of organic matter may strongly influence gas exchange between marine systems and the atmosphere. In order to understand organic matter cycling in surface films, we analyzed SML and underlying water samples at 38 stations determining DOC concentration, amino acid composition, marine gels, CDOM and bacterial and phytoplankton abundance as indicators of photochemical and microbial alteration processes. CDOM composition was characterized by spectral slope (S) values and Excitation-Emission Matrix fluorescence (EEMs), which allow to track changes in molecular weight (MW) of DOM, and to determine potential DOM sources and sinks. We identified five fluorescent components of the CDOM pool, of which two had excitation/emission characteristics of protein-like fluorophores and were highly enriched in the SML. CDOM composition and changes in spectral slope properties suggested a local microbial release of HMW DOM directly in the SML as a response to light exposure in this extreme environment. Our results suggest that microbial and photochemical processes play an important role for the production, alteration and loss of optically active substances in the SML.

The Hygroscopicity Parameter of Marine Organics in Sea Spray Aerosols

NASA Astrophysics Data System (ADS)

Boyer, M.; Chang, R. Y. W.

2015-12-01

The effects of aerosols on climate are poorly understood, specifically with respect to their influence on cloud properties. Since oceans cover >70% of Earth's surface, sea spray aerosols (SSA), which act efficiently as cloud condensation nuclei (CCN), may have important implications on Earth's radiation budget. Surface active organic species readily accumulate in the sea surface microlayer (SML), located at the ocean-atmosphere interface, and transfer onto nascent SSA. While it is understood that SSA are commonly enriched with organics, the resulting effect of the organic content on CCN activation remains unresolved. The hygroscopicity parameter, kappa (k), allows for the cloud nucleating properties of individual components to be predicted in particles of mixed composition; however, most studies typically infer k from ambient measurements without assessing the contribution of the individual components to the overall k. In this study, a method for quantifying the cloud nucleating properties of the organic species in surface seawater using k-Kohler theory is proposed. Ambient SML and bulk water samples will be collected and atomized to generate particles such that the overall k can be inferred from CCN measurements. The inorganic and organic components will be quantified, and the organic component will be separated so that the hygroscopicity of only the organic constituents can be determined. By comparing the inferred k values for the samples before and after removal of the inorganic component, the hygroscopicity of the organic constituents alone can be calculated, providing insight on the effect of organic species on CCN activation in SSA.

Effect of temperature on the accumulation of marine biogenic gels in the surface microlayer near the outlet of nuclear power plants and adjacent areas in the Daya Bay, China.

PubMed

Yue, Wei-Zhong; Sun, Cui-Ci; Shi, Ping; Engel, Anja; Wang, You-Shao; He, Wei-Hong

2018-01-01

The surface microlayer (SML) in marine systems is often characterized by an enrichment of biogenic, gel-like particles, such as the polysaccharide-containing transparent exopolymer particles (TEP) and the protein-containing Coomassie stainable particles (CSP). This study investigated the distribution of TEP and CSP, in the SML and underlying water, as well as their bio-physical controlling factors in Daya Bay, an area impacted by warm discharge from two Nuclear power plants (Npp's) and aquaculture during a research cruise in July 2014. The SML had higher proportions of cyanobacteria and of pico-size Chl a contrast to the underlayer water, particularly at the nearest outlet station characterized by higher temperature. Diatoms, dinoflagellates and chlorophyll a were depleted in the SML. Both CSP and TEP abundance and total area were enriched in the SML relative to the underlying water, with enrichment factors (EFs) of 1.5-3.4 for CSP numbers and 1.32-3.2 for TEP numbers. Although TEP and CSP showed highest concentration in the region where high productivity and high nutrient concertation were observed, EFs of gels and of dissolved organic carbon (DOC) and dissolved acidic polysaccharide (> 1 kDa), exhibited higher values near the outlet of the Npp's than in the adjacent waters. The positive relation between EF's of gels and temperature and the enrichment of cyanobacteria in the SML may be indicative of future conditions in a warmer ocean, suggesting potential effects on adjusting phytoplankton community, biogenic element cycling and air-sea exchange processes.

Steady State Vapor Bubble in Pool Boiling

PubMed Central

Zou, An; Chanana, Ashish; Agrawal, Amit; Wayner, Peter C.; Maroo, Shalabh C.

2016-01-01

Boiling, a dynamic and multiscale process, has been studied for several decades; however, a comprehensive understanding of the process is still lacking. The bubble ebullition cycle, which occurs over millisecond time-span, makes it extremely challenging to study near-surface interfacial characteristics of a single bubble. Here, we create a steady-state vapor bubble that can remain stable for hours in a pool of sub-cooled water using a femtosecond laser source. The stability of the bubble allows us to measure the contact-angle and perform in-situ imaging of the contact-line region and the microlayer, on hydrophilic and hydrophobic surfaces and in both degassed and regular (with dissolved air) water. The early growth stage of vapor bubble in degassed water shows a completely wetted bubble base with the microlayer, and the bubble does not depart from the surface due to reduced liquid pressure in the microlayer. Using experimental data and numerical simulations, we obtain permissible range of maximum heat transfer coefficient possible in nucleate boiling and the width of the evaporating layer in the contact-line region. This technique of creating and measuring fundamental characteristics of a stable vapor bubble will facilitate rational design of nanostructures for boiling enhancement and advance thermal management in electronics. PMID:26837464

Investigating the pathway for the photochemical formation of VOCs in presence of an organic monolayer at the air/water interface.

NASA Astrophysics Data System (ADS)

Tinel, Liselotte; Rossignol, Stéphanie; Ciuraru, Raluca; George, Christian

2015-04-01

Investigating the pathway for the photochemical formation of VOCs in presence of an organic monolayer at the air/water interface. Liselotte Tinel, Stéphanie Rossignol, Raluca Ciuraru and Christian George Université de Lyon, Université Lyon 1, CNRS, UMR5256, IRCELYON, Institut de recherches sur la catalyse et l'environnement de Lyon, Villeurbanne, F-69626, France Recently the surface microlayer (SML) has received growing attention for its role in the deposition and emission of trace gases. This SML is presumably a highly efficient environment for photochemical reactions thanks to its physical and chemical properties, showing enrichment in chromophores [1]. Still, little is known about the possible photochemical processes that could influence the emission and deposition of volatile organic compounds (VOCs) in the SML. A recent study underlines the particularity of the presence of an organic microlayer, showing enhanced formation of peptide bonds at the air-water interface, although this reaction is thermodynamically disfavoured in bulk water [2]. Also, emissions of small gas phase carbonyl compounds formed photochemically by dissolved organic matter have been measured above natural water and glyoxal, for example, measured above the open ocean is thought to be photochemically produced [3, 4]. This study presents the results of a set of laboratory studies set up in order to better understand the role of the SML in the photochemical production of VOCs. Recently, our group has shown the formation of VOCs by light driven reactions in a small quartz reactor (14mL) containing aqueous solutions of humic acids (HA) in the presence of an organic (artificial or natural) microlayer [5]. The main VOCs produced were oxidized species, such as aldehydes, ketones and alcohols, as classically can be expected by the oxidation of the organics present at the interface initiated by triplet excited chromophores present in the HA. But also alkenes, dienes, including isoprene and unsaturated aldehydes were detected and a reaction pathway, initiated by a H-abstraction of the surfactant by the excited HA*, has been proposed. This mechanism infers that the presence of the surface microlayer will enhance protonation and self-reactions, leading to the formation of dimers as suggested in [6]. These products could explain the formation of the unsaturated products observed. To confirm the hypothesis of an initiative step of H-abstraction, the system was simplified using OH radicals, generated by the photolysis of H2O2, in presence of an artificial organic layer of nonanoic acid. The VOCs produced, monitored by PTR/SRI-TOF-MS in NO+ and H3O+ ionization mode, were less abundant compared to the system with HA, but the same classes of products could be observed, including oxidation products such as aldehydes but also unsatured products like dienes. The underlying water was sampled before and after the experiment and analysed by HR-ESI-MS, showing mostly enrichment of oxidative products, such as hydroxy- and keto-acids immediately derived from the photochemical oxidation of the nonanoic acid layer. These products, showing lower volatility and higher polarity, partition preferentially to the bulk water. The results of this simplified system confirm the reaction mechanism proposed and the role an organic layer can play in the photochemical formation of VOCs, which could influence the marine boundary layer chemistry. 1. Peter S. Liss, R.A.D., ed. Sea Surface and Global Change. 1997, Cambridge University Press: Cambridge. 509. 2. Griffith, E.C. and V. Vaida, In situ observation of peptide bond formation at the water-air interface. Proceedings of the National Academy of Sciences, 2012. 109(39): p. 15697-15701. 3. Sinreich, R., et al., Ship-based detection of glyoxal over the remote tropical Pacific Ocean. Atmospheric Chemistry and Physics, 2010. 10(23): p. 11359-11371. 4. Kieber, R.J., X.L. Zhou, and K. Mopper, Formation of carbonyl-compounds from uv-induced photodegradation of humic substances in natural-waters - fate of riverine carbon in the sea. Limnology and Oceanography, 1990. 35(7): p. 1503-1515. 5. R. Ciuraru, L. Fine, M. van Pinxteren, B. D'Anna, H. Herrmann, C. George, Unravelling new processes at interfaces: chemical isoprene production at the sea surface. submitted. 6. Griffith, E.C., et al., Photoinitiated Synthesis of Self-Assembled Vesicles. Journal of the American Chemical Society, 2014. 136(10): p. 3784-3787.

Fundamental investigations of clay/polymer nanocomposites and applications in co-extruded microlayered systems

NASA Astrophysics Data System (ADS)

Decker, Jeremy John

The second and fourth generations of hydroxylated dendritic polyesters (HBP2, HBP4) were combined with unmodified sodium montmorillonite clay (Na +MMT) in water to generate a broad range of polymer clay nanocomposites from 0 to 100% wt/wt Na+MMT. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to investigate intercalation states of the clay galleries. It was shown that interlayer spacings were independent of generation number and changed over the composition range from 0.5 nm to 3.5 nm in 0.5 nm increments that corresponded to a flattened HBP conformation within the clay tactoids. The HBP4/Na+MMT systems were investigated to study the vitrified Rigid Amorphous Fraction (RAF) induced by the clay surfaces. Differential Scanning Calorimetry (DSC) showed changes in heat capacity, Delta Cp, at Tg, that decreased with clay content, until completely suppressed at 80 wt% Na+MMT due to confinement. RAF was quantified from these changes in heat capacity and verified by the analysis of orthopositronium lifetime temperature scans utilizing positron annihilation lifetime spectroscopy (PALS): verifying the glassy nature of the RAF at elevated temperatures. Mathematical relationships allowed for correlation of the interlayer spacings with DeltaC p. RAF formation correlated to intercalated HBP4, and external surfaces of the clay tactoids. The interdiffusion of a polymer pair in microlayers was exploited to increase the concentration of nanoclay particles. When microlayers of a nanocomposite composed of organically modified montmorillonite (M2(HT)2 ) inside maleic anhydride grafted linear low-density polyethylene (LLDPE-g-MA) and low-density polyethylene (LDPE) were taken into the melt, the greater mobility of the linear LLDPE-g-MA chains compared to the branched LDPE chains caused shrinkage of the nanocomposite microlayers, concentrating the M 2(HT)2 contained within. Analysis of the clay morphology within these layers demonstrated an increase in clay particle lengths and aspect ratios, which was attributed to the growth of skewed aggregates during concentration. The melt induced clay concentration and increased clay particle dimensions caused significant decreases in the permeability of the nanocomposite microlayers and reduced the overall permeability of the multilayered films. Morphology and transport behavior of these microlayered films were compared to a series of bulk nanocomposites using a second LLDPE-g-MA containing M 2(HT)2 with varying clay content.

Size-resolved characterization of the polysaccharidic and proteinaceous components of sea spray aerosol

NASA Astrophysics Data System (ADS)

Aller, Josephine Y.; Radway, JoAnn C.; Kilthau, Wendy P.; Bothe, Dylan W.; Wilson, Theodore W.; Vaillancourt, Robert D.; Quinn, Patricia K.; Coffman, Derek J.; Murray, Benjamin J.; Knopf, Daniel A.

2017-04-01

Dissolved organic polymers released by phytoplankton and bacteria abiologically self-assemble in surface ocean waters into nano-to micro-sized gels containing polysaccharides, proteins, lipids and other components. These gels concentrate in the sea surface microlayer (SML), where they can potentially contribute to sea spray aerosol (SSA). Sea spray is a major source of atmospheric aerosol mass over much of the earth's surface, and knowledge of its properties (including the amount and nature of the organic content), size distributions and fluxes are fundamental for determining its role in atmospheric chemistry and climate. Using a cascade impactor, we collected size-fractionated aerosol particles from ambient air and from freshly generated Sea Sweep SSA in the western North Atlantic Ocean together with biological and chemical characterization of subsurface and SML waters. Spectrophotometric methods were applied to quantify the polysaccharide-containing transparent exopolymer (TEP) and protein-containing Coomassie stainable material (CSM) in these particles and waters. This study demonstrates that both TEP and CSM in surface ocean waters are aerosolized with sea spray with the greatest total TEP associated with particles <180 nm in diameter and >5 000 nm. The higher concentrations of TEP and CSM in particles >5 000 nm most likely reflects collection of microorganism cells and/or fragments. The greater concentration of CSM in larger size particles may also reflect greater stability of proteinaceous gels compared to polysaccharide-rich gels in surface waters and the SML. Both TEP and CSM were measured in the ambient marine air sample with concentrations of 2.1 ± 0.16 μg xanthan gum equivalents (XG eq.) m-3 and 14 ± 1.0 μg bovine serum albumin equivalents (BSA eq.) m-3. TEP in Sea Sweep SSA averaged 4.7 ± 3.1 μg XG eq. m-3 and CSM 8.6 ± 7.3 μg BSA eq. m-3. This work shows the transport of marine biogenic material across the air-sea interface through primary particle emission and the first demonstration of particle size discriminated TEP and CSM characterization of SSA and ambient aerosol under field conditions.

The Chemical Composition and Mixing State of Sea Spray Aerosol and Organic Aerosol in the Winter-Spring Arctic

NASA Astrophysics Data System (ADS)

Kirpes, R.; Bondy, A. L.; Bonanno, D.; Moffet, R.; Wang, B.; Laskin, A.; Ault, A. P.; Pratt, K.

2016-12-01

The Arctic region is undergoing rapid transformations and loss of sea ice due to climate change. With increased sea ice fracturing resulting in greater open ocean surface, winter emissions of sea spray aerosol (SSA) are expected to be increasing. Additionally, during the winter-spring transition, Arctic haze contributes to the Arctic aerosol budget. The magnitude of aerosol climate effects depends on the aerosol composition and mixing state (distribution of chemical species within and between particles). However, few studies of aerosol chemistry have been conducted in the winter Arctic, despite it being a time when aerosol impacts on clouds are expected to be significant. To study aerosol composition and mixing state in the winter Arctic, atmospheric particles were collected near Barrow, Alaska in January and February 2014 for off-line individual particle chemical analysis. SSA was the most prevalent particle type observed. Sulfate and nitrate were observed to be internally mixed with SSA and organic aerosol. Greater than 98% of observed SSA particles contained organic content, with 15-35% organic volume fraction on average for individual particles. The SSA organic compounds consisted of carbohydrates, lipids, and fatty acids found in the seawater surface microlayer. SSA was determined to be emitted from open leads, while transported sulfate and nitrate contributed to aging of SSA and organic aerosol. Determining the aerosol chemical composition and mixing state in the winter Arctic will further the understanding of how individual aerosol particles impact climate through radiative effects and cloud formation.

The Impact of Organic Surfactants and Coatings in Regulating Heterogeneous N2O5 Reaction Kinetics on Nascent Marine Aerosol

NASA Astrophysics Data System (ADS)

Ryder, O. S.; Campbell, N.; Schill, S.; Pöhlker, C.; Andreae, M. O.; Bertram, T. H.

2013-12-01

The heterogeneous reaction of N2O5 on aerosol particles impacts both the lifetime of nitrogen oxides, and the production rate of chlorine radicals following the activation of particulate chloride to nitryl chloride in both coastal and continental regions. The extent to which N2O5 reactivity impacts oxidant loadings depends on the heterogeneous reaction rate, which is directly influenced by aerosol chemical composition, morphology, and physical phase state. In the marine environment, the chemical composition of aerosol particles produced via wave induced bubble bursting mechanisms varies greatly and is influenced by the composition of the sea surface microlayer . Here, we present direct measurements of N2O5 reaction kinetics determined using model sea-spray particles generated in a novel Marine Aerosol Reference Tank (MART), capable of generating accurate mimics of ambient sea spray particles, in a lab environment. Here, a synthetic sea salt ocean was sequentially doped with organic molecules chosen to mimic organic species present in natural sea water over the course of a phytoplankton bloom in the open ocean. These included sterol, galactose, lippolysaccharide, BSA protein, and 1,2-dipalmitoyl-sn-glycero-3-phosphate (DPPA). These observations permit discussion of the role of marine organics in regulating heterogeneous reaction kinetics, as well a re-evaluation of potential organic lab proxies for marine organics.

Biodegradation of artificial monolayers applied to water storages to reduce evaporative loss.

PubMed

Pittaway, P; Herzig, M; Stuckey, N; Larsen, K

2015-01-01

Repeat applications of an artificial monolayer to the interfacial boundary layer of large agricultural water storages during periods of high evaporative demand remains the most commercially feasible water conservation strategy. However, the interfacial boundary layer (or microlayer) is ecologically distinct from subsurface water, and repeat monolayer applications may adversely affect microlayer processes. In this study, the natural cleansing mechanisms operating within the microlayer were investigated to compare the biodegradability of two fatty alcohol (C16OH and C18OH) and one glycol ether (C18E1) monolayer compound. The C16OH and C18OH compounds were more susceptible to microbial degradation, but the C18E1 compound was most susceptible to indirect photodegradation. On clean water the surface pressure and evaporation reduction achieved with a compressed C18E1 monolayer was superior to the C18OH monolayer, but on brown water the surface pressure dropped rapidly. These results suggest artificial monolayers are readily degraded by the synergy between photo and microbial degradation. The residence time of C18OH and C18E1 monolayers on clear water is sufficient for cost-effective water conservation. However, the susceptibility of C18E1 to photodegradation indicates the application of this monolayer to brown water may not be cost-effective.

Investigation of pollution characteristics of polychlorinated biphenyls in the typical drinking water sources in Jiangsu Province, China.

PubMed

Hong, Ye; Chunhong, Zhou; Xiaoxiong, Zeng

2009-11-01

Concentration and composition of polychlorinated biphenyls (PCBs) in the typical drinking water sources in Jiangsu Province were studied by scene investigation and physical and chemical analyses as well. Total amount of PCBs in some surface water and surface microlayers exceeded the standard (20 ng/l) in the "Environmental Quality Standard of Surface Water". There were less PCBs in suspended substances and bottom mud. It reflected that there was less PCB pollution in drinking water sources in Jiangsu Province for quite a long period. The main kind of PCBs in the typical drinking water sources was dichlorobiphenyl. Monochlorobiphenyl and trichlorobiphenyl ranked next to dichlorobiphenyl. In the study of PCB distribution in drinking water sources, it was found that the concentration of PCBs in surface microlayer was higher than that in deep water. The concentration of PCBs along the Yangtze River bank was more than that in the middle of Yangtze River. PCBs in the typical drinking water sources mostly came from by-products in industrial production.

Environmental Processing of Lipids Driven by Aqueous Photochemistry of α-Keto Acids

PubMed Central

2018-01-01

Sunlight can initiate photochemical reactions of organic molecules though direct photolysis, photosensitization, and indirect processes, often leading to complex radical chemistry that can increase molecular complexity in the environment. α-Keto acids act as photoinitiators for organic species that are not themselves photoactive. Here, we demonstrate this capability through the reaction of two α-keto acids, pyruvic acid and 2-oxooctanoic acid, with a series of fatty acids and fatty alcohols. We show for five different cases that a cross-product between the photoinitiated α-keto acid and non-photoactive species is formed during photolysis in aqueous solution. Fatty acids and alcohols are relatively unreactive species, which suggests that α-keto acids are able to act as radical initiators for many atmospherically relevant molecules found in the sea surface microlayer and on atmospheric aerosol particles. PMID:29806009

Synthetic ultraviolet light filtering chemical contamination of coastal waters of Virgin Islands National Park, St. John, U.S. Virgin Islands

USGS Publications Warehouse

Bargar, Timothy A.; Alvarez, David; Garrison, Virginia H.

2015-01-01

Contamination of surface waters by synthetic ultraviolet light (UV) filtering chemicals is a concern for the Virgin Islands National Park (VINP). Discrete water samples were collected from VINP bays to determine UV filter chemical presence in the coastal waters. Spatial distribution and the potential for partitioning between subsurface waters and the sea surface microlayer (SML) were also examined. The UV filter chemicals 4-methylbenzylidene camphor, benzophenone-3, octinoxate, homosalate, and octocrylene were detected at concentrations up to 6073 ng/L (benzophenone-3). Concentrations for benzophenone-3 and homosalate declined exponentially (r2 = 0.86 to 0.98) with distance from the beach. Limited data indicate that some UV filter chemicals may partition to the SML relative to the subsurface waters. Contamination of VINP coastal waters by UV filter chemicals may be a significant issue, but an improved understanding of the temporal and spatial variability of their concentrations would be necessary to better understand the risk they present.

Photodegradation of selected polycyclic aromatic hydrocarbons in surface microlayer under direct solar irradiance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, K.; Dickhut, R.M.

1995-12-31

Photodegradation kinetics of selected polycyclic aromatic hydrocarbons (PAHs) in the presence of various particle and dissolved phases were examined in surface microlayer (SM) and surface water under direct solar irradiance during different seasons. Halflives of PAHs during different seasons in the various media were determined. The results showed shorter halflives measured at the surface for PAHs in the SM media than in surface water. Submergence depth also significantly affected rate constants, and halflives for PAH compounds were 1.4 to 5 times shorter at the surface than at 14cm depth below the surface. In bulk SM media, the annual average halflivesmore » varied from 1.3 to 43 hours (midday) with different PAH compounds, and in filtered SM from 1.8 to 56.9 hours (midday). The effects of particles and DOC on the photodegradation of PAHs were also inspected. The results showed particulates and DOC both enhanced or decreased the photodegradation rate constants for selected PAHs. Overall, PAH photoreactivity is related to the compound`s maximum net atomic charge (MNAC) on the most reactive carbon center of a specific PAH molecule.« less

A comparison of microscopic and spectroscopic identification methods for analysis of microplastics in environmental samples.

PubMed

Song, Young Kyoung; Hong, Sang Hee; Jang, Mi; Han, Gi Myung; Rani, Manviri; Lee, Jongmyoung; Shim, Won Joon

2015-04-15

The analysis of microplastics in various environmental samples requires the identification of microplastics from natural materials. The identification technique lacks a standardized protocol. Herein, stereomicroscope and Fourier transform infrared spectroscope (FT-IR) identification methods for microplastics (<1mm) were compared using the same samples from the sea surface microlayer (SML) and beach sand. Fragmented microplastics were significantly (p<0.05) underestimated and fiber was significantly overestimated using the stereomicroscope both in the SML and beach samples. The total abundance by FT-IR was higher than by microscope both in the SML and beach samples, but they were not significantly (p>0.05) different. Depending on the number of samples and the microplastic size range of interest, the appropriate identification method should be determined; selecting a suitable identification method for microplastics is crucial for evaluating microplastic pollution. Copyright © 2015 Elsevier Ltd. All rights reserved.

Occurrence and distribution of bisphenol A and alkylphenols in the water of the Gulf of Gdansk (Southern Baltic).

PubMed

Staniszewska, Marta; Koniecko, Iga; Falkowska, Lucyna; Krzymyk, Ewelina

2015-02-15

In 2011-2012, the concentrations of bisphenol A (BPA), 4-tert-octylophenol (OP) and 4-nonylphenol (NP) in surface and near-bottom water of the Gulf of Gdansk, as well as inflowing rivers, were similar to those in other regions of Europe; BPA from <5.0 to 277.9 ng dm(-3), OP from <1.0 to 834.5 ng dm(-3), and NP from <4.0 to 228.6 ng dm(-3). The atmospheric transportation of phenol derivatives and their deposition into the water of the gulf was indicated by high enrichment factor values (EF) in the sea surface microlayer in relation to the sub-surface layer. The main route of BPA, OP and NP transportation into the waters of the Gulf of Gdansk is the River Vistula. In spring, significant amounts of bisphenol A and 4-nonylphenol were introduced to the coastal zone with meltwater. The main factors affecting the variability of BPA, OP and NP concentrations in surface and near-bottom water, particularly in summer, were increased tourism in the coastal region, water temperature and dissolved oxygen concentration. Copyright © 2014 Elsevier Ltd. All rights reserved.

Preliminary data on formaldehyde content in seawater samples from Terra Nova Bay (Ross Sea - Antarctica)

NASA Astrophysics Data System (ADS)

Largiuni, O.; Becagli, S.; Traversi, R.; Udisti, R.

2003-04-01

Formaldehyde is a key reactive intermediate in the methane oxidation chain. To date, only a few measurements of HCHO in surface seawater have been reported, suggesting a net flux of HCHO from the atmosphere to the ocean surface. Ocean is considered as a sink for atmospheric HCHO, but it cannot be excluded that marine areas characterized by high biogenic activity constitute a source of HCHO to atmosphere. Indeed, laboratory experiments carried out on seawater microlayer show HCHO production by photo-oxidation of dissolved organic matter. To date no measurements on deep seawater samples were performed. A sensitive method for the formaldehyde determination in aqueous sample by Flow Injection Analysis has been applied to seawater samples analysis. The method has a detection limit of 55 ng/l and a reproducibility of 2.5% at 1 ug/l level (5 % in sea water samples). The detector response is linear in the range 0.1 - 3000 ug/l. In the framework of the Italian Research Programme in Antarctica (PNRA), 20 samples were collected in two stations in the Gerlache Inlet (Terra Nova Bay, Western Ross Sea) during the 2001/2002 field campaign (November 2001 to February 2002). The samples were collected through a hole in the sea-ice, along the water column, using a Go-Flo type bottle. Usually, just sub-pack and 30 and 50 m depth fractions were collected. For each depth profile, temperature, salinity and chlorophyll fluorescence signal were measured. Formaldehyde concentrations range from 4.5 to 40 ppb. The relationship between HCHO content and other measured parameters is discussed. The sampling repetition in time at the same sites allowed evaluating the seasonal changes in the formaldehyde concentration/depth profiles.

Resistance of Marine Bacterioneuston to Solar Radiation

PubMed Central

Agogué, Hélène; Joux, Fabien; Obernosterer, Ingrid; Lebaron, Philippe

2005-01-01

A total of 90 bacterial strains were isolated from the sea surface microlayer (i.e., bacterioneuston) and underlying waters (i.e., bacterioplankton) from two sites of the northwestern Mediterranean Sea. The strains were identified by sequence analysis, and growth recovery was investigated after exposure to simulated solar radiation. Bacterioneuston and bacterioplankton isolates were subjected to six different exposure times, ranging from 0.5 to 7 h of simulated noontime solar radiation. Following exposure, the growth of each isolate was monitored, and different classes of resistance were determined according to the growth pattern. Large interspecific differences among the 90 marine isolates were observed. Medium and highly resistant strains accounted for 41% and 22% of the isolates, respectively, and only 16% were sensitive strains. Resistance to solar radiation was equally distributed within the bacterioneuston and bacterioplankton. Relative contributions to the highly resistant class were 43% for γ-proteobacteria and 14% and 8% for α-proteobacteria and the Cytophaga/Flavobacterium/Bacteroides (CFB) group, respectively. Within the γ-proteobacteria, the Pseudoalteromonas and Alteromonas genera appeared to be highly resistant to solar radiation. The majority of the CFB group (76%) had medium resistance. Our study further provides evidence that pigmented bacteria are not more resistant to solar radiation than nonpigmented bacteria. PMID:16151115

Middle Adriatic Study of the Sea Surface Films as a Sink and Source of Trace Organics of Marine Aerosols

NASA Astrophysics Data System (ADS)

Frka Milosavljevic, S.; Cvitešić, A.; Kroflič, A.; Šala, M.; Ciglenečki, I.; Grgic, I.

2016-02-01

Properties, (trans)formation, and removal of organic particles remain the least understood aspects of atmospheric chemistry despite the importance of organic aerosol (OA) for both human health and climate change. Recently, organosulfur compounds (OS) have come into the focus of atmospheric research as significant reservoirs of S in the atmosphere, being potentially important components of gas-to-particle conversion and formation of secondary organic aerosol (SOA) especially in the oceanic region. Moreover, nitroaromatic compounds (NAC), as (methyl)nitrocatehols recently reported as potentially toxic constituents of aerosol water soluble organic matter (WSOM) and significant SOA tracers, have not been studied over marine atmosphere till now. A range of global exchange processes between the sea and the atmosphere is hindered by the sea surface microlayer (SML) generally enriched in surface active organics which form films and serve both as a sink and a source of marine OA. To better understand the role of surfactant films at the air-sea interface in global biogeochemistry as well as the sources and transport pathways of marine OA and to estimate their importance in global climate, it is necessary to study chemical composition and properties of trace organics, OS and NAC, in both the SML and marine aerosols as an integrated whole. We will present the first attempt to study marine aerosol WSOM as well as the SML collected in the Middle Adriatic with a special emphasis on its total S and OS content as well as on specific NAC. For that purpose a novel methodological approach capable of their quantification as well as determination of their surfactant nature is applied by combining liquid chromatography mass spectrometry, ion chromatography, inductively coupled plasma mass spectrometry, and electrochemistry. The obtained data are correlated with those for dissolved and particulate organic carbon, water soluble anions and cations, chlorophyll a, nutrients, and surfactants.

Linking hygroscopicity and the surface microstructure of model inorganic salts, simple and complex carbohydrates, and authentic sea spray aerosol particles.

PubMed

Estillore, Armando D; Morris, Holly S; Or, Victor W; Lee, Hansol D; Alves, Michael R; Marciano, Meagan A; Laskina, Olga; Qin, Zhen; Tivanski, Alexei V; Grassian, Vicki H

2017-08-09

Individual airborne sea spray aerosol (SSA) particles show diversity in their morphologies and water uptake properties that are highly dependent on the biological, chemical, and physical processes within the sea subsurface and the sea surface microlayer. In this study, hygroscopicity data for model systems of organic compounds of marine origin mixed with NaCl are compared to data for authentic SSA samples collected in an ocean-atmosphere facility providing insights into the SSA particle growth, phase transitions and interactions with water vapor in the atmosphere. In particular, we combine single particle morphology analyses using atomic force microscopy (AFM) with hygroscopic growth measurements in order to provide important insights into particle hygroscopicity and the surface microstructure. For model systems, a range of simple and complex carbohydrates were studied including glucose, maltose, sucrose, laminarin, sodium alginate, and lipopolysaccharides. The measured hygroscopic growth was compared with predictions from the Extended-Aerosol Inorganics Model (E-AIM). It is shown here that the E-AIM model describes well the deliquescence transition and hygroscopic growth at low mass ratios but not as well for high ratios, most likely due to a high organic volume fraction. AFM imaging reveals that the equilibrium morphology of these single-component organic particles is amorphous. When NaCl is mixed with the organics, the particles adopt a core-shell morphology with a cubic NaCl core and the organics forming a shell similar to what is observed for the authentic SSA samples. The observation of such core-shell morphologies is found to be highly dependent on the salt to organic ratio and varies depending on the nature and solubility of the organic component. Additionally, single particle organic volume fraction AFM analysis of NaCl : glucose and NaCl : laminarin mixtures shows that the ratio of salt to organics in solution does not correspond exactly for individual particles - showing diversity within the ensemble of particles produced even for a simple two component system.

Sterols as biomarkers in the surface microlayer of the estuarine areas.

PubMed

Alsalahi, Murad Ali; Latif, Mohd Talib; Ali, Masni Mohd; Dominick, Doreena; Khan, Md Firoz; Mustaffa, Nur Ili Hamizah; Nadzir, Mohd Shahrul Mohd; Nasher, Essam; Zakaria, Mohamad Pauzi

2015-04-15

This study aims to determine the concentration of sterols used as biomarkers in the surface microlayer (SML) in estuarine areas of the Selangor River, Malaysia. Samples were collected during different seasons through the use of a rotation drum. The analysis of sterols was performed using gas chromatography equipped with a flame ionisation detector (GC-FID). The results showed that the concentrations of total sterols in the SML ranged from 107.06 to 505.55 ng L(-1). The total sterol concentration was found to be higher in the wet season. Cholesterol was found to be the most abundant sterols component in the SML. The diagnostic ratios of sterols show the influence of natural sources and waste on the contribution of sterols in the SML. Further analysis, using principal component analysis (PCA), showed distinct inputs of sterols derived from human activity (40.58%), terrigenous and plant inputs (22.59%) as well as phytoplankton and marine inputs (17.35%). Copyright © 2015 Elsevier Ltd. All rights reserved.

New insights into modeling an organic mass fraction of sea spray aerosol

NASA Astrophysics Data System (ADS)

Meskhidze, N.; Gantt, B.

2010-12-01

As the study of climate change progresses, a need to separate the effects of natural and anthropogenic processes becomes essential in order to correctly forecast the future climate. Due to their massive source regions underlying an atmosphere with low aerosol concentration, marine aerosols derived from sea spray and ocean emitted biogenic volatile organic compounds (BVOCs) are extremely important for the Earth’s radiative budget, regional air quality and biogeochemical cycling of elements. Measurements of freshly-emitted sea spray have revealed that bubble bursting processes, largely responsible for the production of sea salt aerosol, also control sea-to-air transfer of marine organic matter. It has been established that the organic mass fraction of sea spray can be a function of sea-water composition (e.g., concentrations of Chlorophyll-a, [Chl-a], dissolved organic carbon, [DOC], particulate organic carbon, [POC], types of organic carbon, and the amount of surfactants). Current paramaterizations of marine primary organic aerosol emissions use remotely sensed [Chl-a] data as a proxy for oceanic biological activity. However, it has also been shown that the path length, size, and lifetime of bubbles in seawater as well as spatial coverage of seawater surface by streaks or slicks (visible film of a roughly 50 μm thick layer, highly enriched in organics) can have dramatic effect on organic mass fraction of sea spray (OCss). Dynamics of bubble entrainment and the level of microlayer enrichment by organics relative to the underlying bulk water can be controlled by surface wind speed. For bubble entrainment, high winds can increase rising bubble path length and therefore the amount of organics scavenged by the bubble. However, when the surface wind speeds exceed 8 m s-1 breaking of ocean waves can entirely destroy surface organic films and diminish the amount of organics leaving the sea. Despite the probable impact of wind speed, existing parameterizations do not consider the wind speed dependence of OCss. In this study we use remotely sensed data for ocean slick coverage and surface wind speed in conjunction with an upwind averaged concentrations of [Chl-a], [DOC] and [POC] to derive marine primary organic aerosol emission function. Derived empirical relationships between the aerosol and ocean/meteorological data are then compared to observed OCss at Mace Head and Point Reyes National Seashore. MATLAB curve fitting tool revealed that multi-variable regression analysis (with both wind speed and [Chl-a]) yields a significant improvement between model predicted and observed submicron fraction of OCss. The coefficient of determination increased from R2=0.1 for previous parameterizations to R2=0.6. Based on the results of this study we propose that in addition to sea-water composition, future parameterizations of marine primary organic aerosol emissions should include sea spray organic mass fraction dependence on surface wind speed.

A Campaign Study of Sea Spray Aerosol Properties in the Bay of Aarhus

NASA Astrophysics Data System (ADS)

Nguyen, Quynh; Rasmussen, Berit; Kristensen, Kasper; Sloth Nielsen, Lærke; Bilde, Merete

2016-04-01

The oceans of the world are a dominant source of atmospheric aerosol. Together with mineral dust, sea spray aerosols (SSA) constitute the largest mass flux of particulate matter in the atmosphere (Andreae and Rosenfeld, 2008). Due to their effects on the global radiative budget - both directly as scatterers and absorbers of solar and terrestrial radiation, and indirectly as cloud condensation nuclei (CCN), SSA are considered an important component of the climate system. The sea-surface microlayer (SML) is an ultra-thin boundary layer between the ocean and the atmosphere. The high concentration of surface-active organic compounds in the SML, compared to that of the underlying water column, creates rigid film-like layer over the surface of the ocean. The SML is believed to play an important role in the formation and composition of SSA. However, current knowledge on the SML and its impacts on SSA remain limited. To characterize the SML of natural seawater and examine its impacts on aerosol properties, a field campaign was conducted in the bay of Aarhus, Denmark, during spring 2015. Bulk seawater was collected 1-2 times every week along with selective sampling of the SML. Characterization of the sea water and SML included a wide range of measurements, including surface tension, water activity, dissolved organic matter, and chemical composition analysis by liquid chromatography/electrospray ionization high-resolution quadrupole time-of-flight mass spectrometry (UPLC/ESI-HR-Q-TOFMS). SSA was generated from sampled sea water by diffusion of air bubbles through a 10L seawater sample situated in a sea spray tank. Particle number concentration and CCN measurements were conducted along with measurements of the organic share in the aerosol phase as indicated by volatility measurements. To investigate the effect of the SML, spiking of the seawater samples with additional SML was performed and measurements repeated for comparison. Preliminary results show that the SML samples only displayed slightly lower surface tension compared to subsurface seawater. A number of overlapping masses were observed in dissolved organic matter extracted from SML and slick samples, which requires further identification. Spiking bulk seawater with SML seems to lead to a small increase in organic share in the aerosol phase as indicated by volatility measurements, while the trend is unclear in CCN measurements. Andreae, M. O., and Rosenfeld, D.: Aerosol-cloud-precipitation interactions. Part 1. The nature and sources of cloud-active aerosols, Earth-Sci Rev, 89, 13-41, 2008.

Natural Surfactant Enrichments in the Atlantic Ocean Between 50°N and 50°S: Data from the Atlantic Meridional Transect, Oct-Nov 2014

NASA Astrophysics Data System (ADS)

Sabbaghzadeh, B.; Upstill-Goddard, R. C.; Nightingale, P. D.; Beale, R.

2016-02-01

Surfactants that decrease air-sea gas exchange by suppressing the gas transfer velocity (kw) show variable enrichments in the sea surface microlayer (SML) relative to the underlying water. This reflects variability in the rates of surfactant production and consumption. Total surfactant activity (SA: equivalent to Triton-X-100, mgL -1) was determined daily between the UK and the Falkland Islands, during cruise 24 of the Atlantic Meridional Transect programme (AMT 24). Samples were simultaneously obtained from the SML (Garrett screen), from the ship's underway system (inlet at 7m) and in hydrocasts to 500m. SA analysis was by hanging mercury drop electrode polarography (Metrohm 797 VA Computrace). SA enrichment factors (EF: SML SA / underlying water SA) >1 were observed at most locations, showing the SML to be consistently SA-enriched along the entire cruise transect. The persistence of these enrichments up to wind speeds 12m s-¹ support previous conclusions regarding the stability of the SML under high winds. More specifically, SA in the SML was up to four-fold higher in the Atlantic Northern Hemisphere than in the Atlantic Southern Hemisphere. Even so, EF values were not significantly different between the two hemispheres (p >0.05). These various findings have potentially important implications for kw variability across ocean basin scales.

Surfactant control of air-sea gas exchange across contrasting biogeochemical regimes

NASA Astrophysics Data System (ADS)

Pereira, Ryan; Schneider-Zapp, Klaus; Upstill-Goddard, Robert

2014-05-01

Air-sea gas exchange is important to the global partitioning of CO2.Exchange fluxes are products of an air-sea gas concentration difference, ΔC, and a gas transfer velocity, kw. The latter is controlled by the rate of turbulent diffusion at the air-sea interface but it cannot be directly measured and has a high uncertainty that is now considered one of the greatest challenges to quantifying net global air-sea CO2 exchange ...(Takahashi et al., 2009). One important control on kw is exerted by sea surface surfactants that arise both naturally from biological processes and through anthropogenic activity. They influence gas exchange in two fundamental ways: as a monolayer physical barrier and through modifying sea surface hydrodynamics and hence turbulent energy transfer. These effects have been demonstrated in the laboratory with artificial surfactants ...(Bock et al., 1999; Goldman et al., 1988) and through purposeful surfactant releases in coastal waters .(.).........().(Brockmann et al., 1982) and in the open ocean (Salter et al., 2011). Suppression of kwin these field experiments was ~5-55%. While changes in both total surfactant concentration and the composition of the natural surfactant pool might be expected to impact kw, the required in-situ studies are lacking. New data collected from the coastal North Sea in 2012-2013 shows significant spatio-temporal variability in the surfactant activity of organic matter within the sea surface microlayer that ranges from 0.07-0.94 mg/L T-X-100 (AC voltammetry). The surfactant activities show a strong winter/summer seasonal bias and general decrease in concentration with increasing distance from the coastline possibly associated with changing terrestrial vs. phytoplankton sources. Gas exchange experiments of this seawater using a novel laboratory tank and gas tracers (CH4 and SF6) demonstrate a 12-45% reduction in kw compared to surfactant-free water. Seasonally there is higher gas exchange suppression in the summer months likely from primary production and spatially there is less suppression of air-sea gas exchange with increasing distance from the shoreline, which is likely due to riverine inputs. REFERENCES Bock, E. J., Hara, T., Frew, N. M., and McGillis, W. R., 1999. Relationship between air-sea gas transfer and short wind waves. Journal of Geophysical Research-Oceans 104, 25821-25831. Brockmann, U. H., Huhnerfuss, H., Kattner, G., Broecker, H. C., and Hentzschel, G., 1982. Artificial surface-films in the sea area near sylt. Limnology and Oceanography 27, 1050-1058. Goldman, J. C., Dennett, M. R., and Frew, N. M., 1988. Surfactant effects on air sea gas-exchange under turbulent conditions. Deep-Sea Research Part a-Oceanographic Research Papers 35, 1953-1970. McKenna, S. P. and McGillis, W. R., 2004. The role of free-surface turbulence and surfactants in air-water gas transfer. International Journal of Heat and Mass Transfer 47, 539-553. Salter, M. E., R. C. Upstill-Goddard, P. D. Nightingale, S. D. Archer, B. Blomquist, D. T. Ho, B. Huebert, P. Schlosser, and M. Yang (2011), Impact of an artificial surfactant release on air-sea gas fluxes during Deep Ocean Gas Exchange Experiment II, J. Geophys. Res., 116, C11016, doi:10.1029/2011JC00702 Takahashi, T., Sutherland, S. C., Wanninkhof, R., Sweeney, C., Feely, R. A., Chipman, D. W., Hales, B., Friederich, G., Chavez, F., Sabine, C., Watson, A., Bakker, D. C. E., Schuster, U., Metzl, N., Yoshikawa-Inoue, H., Ishii, M., Midorikawa, T., Nojiri, Y., Körtzinger, A., Steinhoff, T., Hoppema, M., Olafsson, J., Arnarson, T. S., Tilbrook, B., Johannessen, T., Olsen, A., Bellerby, R., Wong, C. S., Delille, B., Bates, N. R., and de Baar, H. J. W., 2009. Climatological mean and decadal change in surface ocean pCO 2, and net sea-air CO 2 flux over the global oceans. Deep-Sea Research Part II: Topical Studies in Oceanography 56, 554-577.

A high-fidelity approach towards simulation of pool boiling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yazdani, Miad; Radcliff, Thomas; Soteriou, Marios

2016-01-15

A novel numerical approach is developed to simulate the multiscale problem of pool-boiling phase change. The particular focus is to develop a simulation technique that is capable of predicting the heat transfer and hydrodynamic characteristics of nucleate boiling and the transition to critical heat flux on surfaces of arbitrary shape and roughness distribution addressing a critical need to design enhanced boiling heat transfer surfaces. The macro-scale of the phase change and bubble dynamics is addressed through employing off-the-shelf Computational Fluid Dynamics (CFD) methods for interface tracking and interphase mass and energy transfer. The micro-scale of the microlayer, which forms atmore » early stage of bubble nucleation near the wall, is resolved through asymptotic approximation of the thin-film theory which provides a closed-form solution for the distribution of the micro-layer and its influence on the evaporation process. In addition, the sub-grid surface roughness is represented stochastically through probabilistic density functions and its role in bubble nucleation and growth is then represented based on the thermodynamics of nucleation process. This combination of deterministic CFD, local approximation, and stochastic representation allows the simulation of pool boiling on any surface with known roughness and enhancement characteristics. The numerical model is validated for dynamics and hydrothermal characteristics of a single nucleated bubble on a flat surface against available literature data. In addition, the prediction of pool-boiling heat transfer coefficient is verified against experimental measurements as well as reputable correlations for various roughness distributions and different surface orientations. Finally, the model is employed to demonstrate pool-boiling phenomenon on enhanced structures with reentrance cavities and to explore the effect of enhancement feature design on thermal and hydrodynamic characteristics of these surfaces.« less

The bacterial community composition of the surface microlayer in a high mountain lake.

PubMed

Hörtnagl, Paul; Pérez, Maria Teresa; Zeder, Michael; Sommaruga, Ruben

2010-09-01

The existence of bacterioneuston in aquatic ecosystems is well established, but little is known about its composition and dynamics, particularly in lakes. The bacterioneuston underlies extreme conditions at the air-water boundary, which may influence its dynamics in a different way compared with the bacterioplankton. In this study, we assessed quantitative changes in major bacterial groups of the surface microlayer (SML) (upper 900 microm) and the underlying water (ULW) (0.2-0.5 m depth) of an alpine lake during two consecutive ice-free seasons. Analysis of the bacterial community composition was done using catalyzed reporter deposition FISH with oligonucleotide probes. In addition, several physicochemical parameters were measured to characterize these two water layers. Dissolved organic carbon was consistently enriched in the SML and the dissolved organic matter pool presented clear signals of photodegradation and photobleaching. The water temperature was generally colder in the SML than in the subsurface. The bacterial community of the SML and the ULW was dominated by Betaproteobacteria and Actinobacteria. The bacterial community composition was associated with different combinations of physicochemical factors in these two layers, but temporal changes showed similar trends in both layers over the two seasons. Our results identify the SML of alpine lakes as a microhabitat where specific bacterial members such as of Betaproteobacteria seem to be efficient colonizers.

The Surface Microlayer: Review of Literature and Evaluation of Potential Effects of Dredge Activities in Puget Sound.

DTIC Science & Technology

1987-01-01

Heyrand. 1975. Polonium - 210 - Its vertical oceanic transport by zoo- plankton metabolic activity. Marine Chemistry 3:105-110. Collins, J. 1974. Oil and...Toxicology Environ. Health 7:991-1000. Hose, J.E., J.B. Hannah, D. Dijulio, M.L. Landolt, B.S. Miller, W.T. Iwaoka, and S.P. Felton. 1982. Effects of benzo(a...A184 885 THE SURFACE MICROLAVER, REVIEWJ OF LITERATURE AND 1/2 EVALUATION OF POTENTIAL EFFECTS OF DREDGE ACTIVITIES IN PUGET SOUND(U) EVANS-HAMILTON

Sea spray as a source of ice nucleating particles - results from the AIDA Ocean03 campaign

NASA Astrophysics Data System (ADS)

Salter, M. E.; Ickes, L.; Adams, M.; Bierbauer, S.; Bilde, M.; Christiansen, S.; Ekman, A.; Gorokhova, E.; Höhler, K.; Kiselev, A. A.; Leck, C.; Mohr, C.; Mohler, O.; Murray, B. J.; Porter, G.; Ullrich, R.; Wagner, R.

2017-12-01

Clouds and their radiative effects are one of the major influences on the radiative fluxes in the atmosphere, but at the same time they remain the largest uncertainty in climate models. This lack of understanding is especially pronounced in the high Arctic. Summertime clouds can persist over long periods in this region, which is difficult to replicate in models based on our current understanding. The clouds most often encountered in the summertime high Arctic consist of a mixture of ice crystals and super-cooled water droplets, so-called mixed-phase clouds. This cloud type is sensitive to the availability of aerosol particles, which can act as cloud condensation nuclei and ice nuclei. However, since the high Arctic is a pristine region, aerosol particles are not very abundant, and the hypothesis of open leads in the Arctic as a potentially important source of cloud and ice nucleating particles via bubble bursting has emerged. In this context, we have conducted a series of experiments at the AIDA chamber at KIT, designed to investigate the mechanisms linking marine biology, seawater chemistry and aerosol physics/potential cloud impacts. During this campaign, two marine diatom species (Melosira arctica and Skeletonema marinoi) as well as sea surface microlayer samples collected during several Arctic Ocean research cruises were investigated. To aerosolize the samples, a variety of methods were used including a sea spray simulation chamber to mimic the process of bubble-bursting. The ice nucleating efficiency (mixed-phase cloud regime) of the samples was determined either directly in the AIDA chamber during adiabatic expansions, or using the INKA continuous flow diffusion chamber, or a cold stage. Results from the campaign along with the potential implications are presented.

Graphene-copper composite with micro-layered grains and ultrahigh strength

PubMed Central

Wang, Lidong; Yang, Ziyue; Cui, Ye; Wei, Bing; Xu, Shichong; Sheng, Jie; Wang, Miao; Zhu, Yunpeng; Fei, Weidong

2017-01-01

Graphene with ultrahigh intrinsic strength and excellent thermal physical properties has the potential to be used as the reinforcement of many kinds of composites. Here, we show that very high tensile strength can be obtained in the copper matrix composite reinforced by reduced graphene oxide (RGO) when micro-layered structure is achieved. RGO-Cu powder with micro-layered structure is fabricated from the reduction of the micro-layered graphene oxide (GO) and Cu(OH)2 composite sheets, and RGO-Cu composites are sintered by spark plasma sintering process. The tensile strength of the 5 vol.% RGO-Cu composite is as high as 608 MPa, which is more than three times higher than that of the Cu matrix. The apparent strengthening efficiency of RGO in the 2.5 vol.% RGO-Cu composite is as high as 110, even higher than that of carbon nanotube, multilayer graphene, carbon nano fiber and RGO in the copper matrix composites produced by conventional MLM method. The excellent tensile and compressive strengths, high hardness and good electrical conductivity are obtained simultaneously in the RGO-Cu composites. The results shown in the present study provide an effective method to design graphene based composites with layered structure and high performance. PMID:28169306

Biogeochemical linkage between atmosphere and ocean in the eastern equatorial Pacific Ocean: Results from the EqPOS research cruise

NASA Astrophysics Data System (ADS)

Furutani, H.; Inai, Y.; Aoki, S.; Honda, H.; Omori, Y.; Tanimoto, H.; Iwata, T.; Ueda, S.; Miura, K.; Uematsu, M.

2012-12-01

Eastern equatorial Pacific Ocean is a unique oceanic region from several biogeochemical points of view. It is a remote open ocean with relatively high marine biological activity, which would result in limited influence of human activity but enhanced effect of marine natural processes on atmospheric composition. It is also characterized as high nutrient low chlorophyll (HNLC) ocean, in which availability of trace metals such as iron and zinc limits marine primary production and thus atmospheric deposition of these trace elements to the ocean surface is expected to play an important role in regulating marine primary production and defining unique microbial community. High sea surface temperature in the region generates strong vertical air convection which efficiently brings tropospheric atmospheric composition into stratosphere. In this unique eastern equatorial Pacific Ocean, EqPOS (Equatorial Pacific Ocean and Stratospheric/Tropospheric Atmospheric Study) research cruise was organized as a part of SOLAS Japan activity to understand biogeochemical ocean-atmospheric interaction in the region. Coordinated atmospheric, oceanic, and marine biological observations including sampling/characterization of thin air-sea interfacial layer (sea surface microlayer: SML) and launching large stratospheric air sampling balloons were carried out on-board R/V Hakuho Maru starting from 29 January for 39 days. Biogeochemically important trace/long-lived gases such as CO2, dimethyl sulfide (DMS), and some volatile organic carbons (VOCs) both in the atmosphere and seawater were continuously monitored and their air-sea fluxes were also observed using gradient and eddy-covariance techniques. Atmospheric gas measurement of CO2, CH4, N2O, SF6, CO, H2, Ar and isotopic composition of selected gases were further extended to stratospheric air by balloon-born sampling in addition to a vertical profiling of O3, CO2, and H2O with sounding sondes. Physical and chemical properties of marine atmospheric aerosols such as size distribution, total and cloud condensation nuclei concentrations, particle morphology, bulk and single particle chemical composition were also continuously determined to find out potential link between biogenic VOCs emitted from the ocean and aerosol composition. Biological and biogeochemical characterizations of marine microorganisms, suspended particulate matter, dissolved nutrients in seawater and SML were also conducted. In the presentation, brief overview of the research activities during the EqPOS cruise and biogeochemical linkage atmosphere and ocean via atmospheric and oceanic gaseous and particulate matter from ocean surface to stratosphere observed during the cruise and unique importance of SML would be presented.

On the imprint of surfactant-driven stabilization of laboratory breaking wave foam with comparison to oceanic whitecaps

NASA Astrophysics Data System (ADS)

Callaghan, A. H.; Deane, G. B.; Stokes, M. D.

2017-08-01

Surfactants are ubiquitous in the global oceans: they help form the materially-distinct sea surface microlayer (SML) across which global ocean-atmosphere exchanges take place, and they reside on the surfaces of bubbles and whitecap foam cells prolonging their lifetime thus altering ocean albedo. Despite their importance, the occurrence, spatial distribution, and composition of surfactants within the upper ocean and the SML remains under-characterized during conditions of vigorous wave breaking when in-situ sampling methods are difficult to implement. Additionally, no quantitative framework exists to evaluate the importance of surfactant activity on ocean whitecap foam coverage estimates. Here we use individual laboratory breaking waves generated in filtered seawater and seawater with added soluble surfactant to identify the imprint of surfactant activity in whitecap foam evolution. The data show a distinct surfactant imprint in the decay phase of foam evolution. The area-time-integral of foam evolution is used to develop a time-varying stabilization function, ϕ>(t>) and a stabilization factor, Θ, which can be used to identify and quantify the extent of this surfactant imprint for individual breaking waves. The approach is then applied to wind-driven oceanic whitecaps, and the laboratory and ocean Θ distributions overlap. It is proposed that whitecap foam evolution may be used to determine the occurrence and extent of oceanic surfactant activity to complement traditional in-situ techniques and extend measurement capabilities to more severe sea states occurring at wind speeds in excess of about 10 m/s. The analysis procedure also provides a framework to assess surfactant-driven variability within and between whitecap coverage data sets.