Shift In Size Distribution Research Articles

Particulate matter emission comparison from conventional and premixed low temperature combustion with diesel, biodiesel and biodiesel–ethanol fuels

As worldwide energy and environmental pressures increase, interest in biofuels such as biodiesel and ethanol, and low emission diesel combustion modes such as premixed low temperature combustion (LTC), continues to grow. This study takes a detailed look at particulate matter (PM) from a single cylinder common rail diesel engine operated under conventional and premixed LTC combustion modes with diesel, biodiesel and biodiesel–ethanol fuels. Soot, particle number and particle size distribution are investigated.Experiments show that for conventional combustion, accumulation mode particulates are reduced by biodiesel and reduced further by biodiesel-E20 (20% ethanol by volume). The reduction is attributed to higher fuel oxygen content, lower stoichiometric air–fuel ratio and reduced aromatic content reducing carbonaceous soot. Nucleation mode particles from conventional combustion with diesel, biodiesel and biodiesel-E20 fuels show similar size distributions.For premixed LTC, biodiesel shifts the accumulation mode size distribution curve upwards (i.e., more particles) and towards smaller size particles relative to diesel. In LTC, biodiesel produces more semi-volatile organic carbon and lower soot. The shift in size distribution for biodiesel may be caused by more semi-volatile organic carbon in the exhaust causing an increase in the growth of particles nucleated from volatile species, and less soot leading to a reduction in the number of large carbonaceous agglomerates. Biodiesel-E20 decreases accumulation mode particles of all sizes by reducing soot and the amount of biodiesel-derived semi-volatile organic carbon available for growing particles.Biodiesel increases LTC nucleation mode particles relative to diesel. Biodiesel-E20 increases the amount of small nucleation particles (<20nm) and decreases the amount of large nucleation particles (20–50nm) relative to diesel. The increases in nucleation particles for biodiesel and small nucleation particles (<20nm) for biodiesel-E20 are believed to be caused by less soot and more exhaust semi-volatile organic carbon causing increased nucleation. Biodiesel-B20 produces the lowest soot and total particle number concentration, both at conventional and premixed LTC, demonstrating its potential as an alternative fuel for diesel engines.

Evidence that Tuber Respiration is the Pacemaker of Physiological Aging in Seed Potatoes (Solanum tuberosum L.)

Storage temperatures greater than 4 °C (that is, heat-unit accumulation) increase respiration and accelerate physiological aging of seed tubers. The degree of apical dominance is a good indicator of physiological age (PAGE). As seed age advances, apical dominance decreases, resulting in more stems, greater tuber set, and shifts in tuber size distribution. Herein we provide evidence that tuber respiration rate may constitute the “pacemaker” of aging. Tubers exposed to a brief high-temperature age-priming treatment initially in storage, followed by holding at 4 °C for the remainder of a 190–200-day storage period, maintained a higher basal metabolic (respiration) rate throughout storage compared with tubers stored the entire season at 4 °C. Tubers thus “remembered” the age-priming treatment as reflected by their elevated respiration rate. Moreover, reducing the respiration rate of age-primed seed by subsequently storing it at 3.5 % O2 (4 °C) until planting significantly attenuated the effects of the aging treatment on apical dominance, tuber set, and size distribution. The effect of the age-priming treatment on the magnitude of the respiratory response was the same whether given at the beginning or toward the end of storage. However, moving the age-priming treatment progressively later in the storage season effectively decreased its impact on plant growth and development. These results underscore the importance of time in the aging process. Exposure of seed to a high-temperature age-priming treatment at the beginning or end of storage elevated respiration (the pacemaker) to the same extent; however, the timing of these treatments resulted in vastly different physiological ages. The longer the respiration rate of tubers remains at an elevated level, the greater their PAGE at planting. Thus, an accurate but impractical measure of PAGE may be the respiratory output from vine kill to subsequent planting. Respiration appears to be the pacemaker of PAGE and production, and storage conditions that affect respiration may “set the clock speed” that will ultimately determine the PAGE at planting.

Recombinant Acylation Stimulating Protein Administration to C3−/− Mice Increases Insulin Resistance via Adipocyte Inflammatory Mechanisms

BackgroundComplement 3 (C3), a key component of the innate immune system, is involved in early inflammatory responses. Acylation stimulating protein (ASP; aka C3adesArg), a C3 cleavage product, is produced in adipose tissue and stimulates lipid storage. We hypothesized that, depending on the diet, chronic ASP administration in C3−/− mice would affect lipid metabolism and insulin sensitivity via an adaptive adipose tissue inflammatory response.Methodology/Principal FindingsC3−/− mice on normal low fat diet (ND) or high fat diet (HFD) were chronically administered recombinant ASP (rASP) for 25 days via an osmotic mini-pump. While there was no effect on food intake, there was a decrease in activity, with a relative increase in adipose tissue weight on ND, and a shift in adipocyte size distribution. While rASP administration to C3−/− mice on a ND increased insulin sensitivity, on a HFD, rASP administration had the opposite effect. Specifically, rASP administration in C3−/− HFD mice resulted in decreased gene expression of IRS1, GLUT4, SREBF1 and NFκB in muscle, and decreased C5L2 but increased JNK, CD36, CD11c, CCR2 and NFκB gene expression in adipose tissue as well as increased secretion of proinflammatory cytokines (Rantes, KC, MCP-1, IL-6 and G-CSF). In adipose tissue, although IRS1 and GLUT4 mRNA were unchanged, insulin response was reduced.ConclusionThe effects of chronic rASP administration are tissue and diet specific, rASP administration enhances the HFD induced inflammatory response leading to an insulin-resistant state. These results suggest that, in humans, the increased plasma ASP associated with obesity and cardiovascular disease could be an additional factor directly contributing to development of metabolic syndrome, insulin resistance and diabetes.

Shift of high-density lipoprotein size distribution toward large particles in patients with proteinuria

BackgroundThe potential atheroprotective role of the different HDL subclasses may depend on the metabolic factors that affect their plasma concentrations. The kidney is supposed to be one of the main catabolic sites for these lipoproteins. However, little is known about the impact of proteinuria on HDL size distribution and HDL structure. The aim of this study is to establish the influence of proteinuria on HDL size distribution and cholesterol plasma concentration of HDL subclasses. MethodsForty patients within a range of proteinuria from 0.2 to 10.0g/g estimated by the urinary protein-to-creatinine ratio and 40 healthy controls were enrolled in the study. HDL subclasses were separated by sequential ultracentrifugation followed by a polyacrylamide gradient electrophoresis; gels were stained enzymatically for cholesterol and with Coomasie blue for proteins. HDL size distribution and plasma concentration of the five HDL subclasses were calculated by optical densitometry. ResultsWhen determined by protein, large HDL2b and HDL2a relative proportions were higher in patients than in control subjects, whereas the contrary was observed for small HDL3b and 3c. Consistently, HDL3a, 3b, and 3c were negatively correlated with proteinuria when data were adjusted by age, gender, body mass index, and blood pressure. Size distribution followed a different pattern when determined by cholesterol, suggesting an abnormal lipid composition that was further supported by a protein-to-cholesterol ratio significantly higher in most of the HDL subclasses in proteinuric patients than in the control group. Moreover, proteinuria statistically explains the HDL2b and HDL3c cholesterol plasma concentrations. ConclusionsProteinuria is associated with a shift of HDL size distribution towards large particles and cholesterol-poor HDL subclasses. These results support the idea of a selective loss by the kidney of small HDL in patients with proteinuria; whether these abnormalities reflect an impaired reverse cholesterol transport and an increased risk of coronary heart disease remains to be elucidated.

Contribution of zooplankton fecal pellets to deep ocean particle flux in the Sargasso Sea assessed using quantitative image analysis

Fecal pellet flux and size distribution at 500, 1500 and 3200 m depths were measured in sediment trap samples collected by the Oceanic Flux Program time-series off Bermuda, December 2006–November 2007. During the study, three mesoscale eddies passed through: a cyclonic eddy in bloom stage (February through mid-April), a decaying post-bloom mode-water eddy (late April through May), and an anticyclonic eddy (August through October). Variability associated with eddy passage masked any seasonal trends in flux or size distributions. At a depth of 1500 m, the fecal pellet flux ranged from a minimum of 100 pellets m−2 day−1 to a maximum of 500 pellets m−2 day−1 during the cyclonic eddy passage, corresponding to ranges in the fecal pellet mass and the carbon flux of 0.5–1.7 mg m−2 day−1 and 0.07–0.25 mg C m−2 day−1, respectively. Fecal pellets averaged 7 ± 3% of the organic carbon flux, a minimum estimate as disassociated pellets were not quantifiable. Size distribution shifts indicated small zooplankton and immature stages were more abundant within the cyclonic eddy, whereas larger zooplankton were present within the mode water and anticyclonic eddies. The fecal pellet number, flux and size distributions showed no consistent depth trends and indicated extensive fecal pellet reprocessing within the water column.

A combined experimental and modeling approach to study the effects of high-shear wet granulation process parameters on granule characteristics

The purpose of the current work is to study the effects of high-shear wet granulation process parameters on granule characteristics using both experimental and modeling techniques. A full factorial design of experiments was conducted on three process parameters: water amount, impeller speed and wet massing time. Statistical analysis showed that the water amount has the largest impact on the granule characteristics, and that the effect of other process variables was more pronounced at higher water amount. At high water amounts, an increase in impeller speed and/or wet massing time showed a decrease in granule porosity and compactability. A strong correlation between granule porosity and compactability was observed. A three-dimensional population balance model which considers agglomeration and consolidation was employed to model the granulation process. The model was calibrated using the particle size distribution from an experimental batch to ensure a good match between the simulated and experimental particle size distribution. The particle size distribution of three other batches were predicted, each of which was manufactured under different process parameters (water amount, impeller speed and wet massing time). The model was able to capture and predict successfully the shifts in granule particle size distribution with changes in these process parameters.

Atomic Layer Deposition‐Modified Ordered Mesoporous Silica Membranes

AbstractMesoporous silica membranes, prepared by surfactant‐templating with a pore diameter of ∼4 nm on an alumina support, are modified by atomic layer deposition (ALD) of aluminum oxide. ALD of aluminum oxide is achieved using trimethyl aluminum (TMA) and water as reactants. Membranes modified up to 50 ALD reaction cycles are characterized periodically during progressive reaction cycles to provide details of the pore modification process. A decrease in light gas permeance, pore size distribution shift to lower pore sizes, and a decrease in porosity provide evidence for pore‐size reduction through ALD. Further analysis of the data indicates that the ALD reaction favors larger pores and defects, and becomes less efficient as the pore size decreases.

High Yield CdSe Nanocrystalline Fabrication by a Facial Way Based on Complex Ligands

High quality CdSe nanorcrystallines (NCs) have been fabricated in high yield by a simple hydrothermal method using complex ligands. We find that the morphology and the size of CdSe NCs are related to the experiment conditions such as the composition of complex ligands, the Cd to Se ratio and the precursor concentration. Specifically, CdSe nanorods with wurtzite structure can be obtained when using single n-Octadecylphosphonic acid (ODPA) as ligands. Dots shaped CdSe NCs with different size will be obtained when using complex ligands ODPA and carboxyl acid. The length of carboxyl has great effects on the final products and CdSe NCs with large size will be obtained in the case of using carboxyl acid with short carbon length. On the other hand, a red shift in PL peak and broad size distribution are found with carboxyl acid concentration increase. As the simple preparing process, this method is very useful for large scale fabrication of high quality CdSe NCs for solar cells application.

Numerical Simulation of Effects of Cloud Top Temperatures and Generating Cells on Secondary Ice Production in Stratiform Clouds with a Detailed Microphysical Model

This paper outlines a one-dimensional, heightdependent bin model with detailed microphysical processes in which ice splinters are produced by a riming process. The model is then applied to simulate the shift of particle size distribution effected by the secondary ice production process within clouds with different generating cells and cloud top temperatures. The result of model simulations reveals the general effects of cloud updrafts on increasing ice particle concentration by extending the residence time of ice particles in clouds and providing sufficiently large supercooled water droplets. The rimesplintering mechanism is more effective in clouds with lower ice seeding rates than those with higher rates. Evolutions of hydrometeor size distribution triggered by the rime-splintering mechanism indicate that the interaction between large ice particles and supercooled water drops adds a “second maximum” to the primary ice spectra.

The Effect of Uniform Particle Size Distribution on Pt Stability

The present study aims to address the effect of the uniformity of particle size distribution on Pt stability. A theoretical model based on the chemical reactions of Pt oxidation and precipitation in the membrane is presented. The incorporation of a particle size distribution function and a population balance allows the investigation of different initial particle size distributions. Initial results demonstrate the change of platinum ions concentration across the electrode and membrane and reveal the shift of particle size distribution towards larger diameters under potential hold and potential cycling simulations.

Remarkable dynamics of nanoparticles in the urban atmosphere

Abstract. Nanoparticles emitted from road traffic are the largest source of respiratory exposure for the general public living in urban areas. It has been suggested that adverse health effects of airborne particles may scale with airborne particle number, which if correct, focuses attention on the nanoparticle (less than 100 nm) size range which dominates the number count in urban areas. Urban measurements of particle size distributions have tended to show a broadly similar pattern dominated by a mode centred on 20–30 nm diameter emitted by diesel engine exhaust. In this paper we report the results of measurements of particle number concentration and size distribution made in a major London park as well as on the BT Tower, 160 m aloft. These measurements taken during the REPARTEE project (Regents Park and BT Tower experiment) show a remarkable shift in particle size distributions with major losses of the smallest particle class as particles are advected away from the traffic source. In the Park, the traffic related mode at 20–30 nm diameter is much reduced with a new mode at &lt;10 nm. Size distribution measurements also revealed higher number concentrations of sub-50 nm particles at the BT Tower during days affected by higher turbulence as determined by Doppler Lidar measurements and are indicative of loss of nanoparticles from air aged during less turbulent conditions. These results are suggestive of nanoparticle loss by evaporation, rather than coagulation processes. The results have major implications for understanding the impacts of traffic-generated particulate matter on human health.

Seasonal Variation of Airborne Particle Deposition Efficiency in the Human Respiratory System

Particulate matter (PM) is associated with human health effects but the apparent toxicity of PM in epidemiological studies varies with season. PM toxicity may change due to seasonal shifts in composition or particle size distributions that in turn affect respiratory deposition efficiencies. In the current study, size-resolved PM composition was measured in the largest city (Fresno) in California's heavily polluted San Joaquin Valley during the summer (30 days) and winter (20 days) between 2006 and 2009 for 21 metals, organic carbon, elemental carbon, and 7 water-soluble ions. The Multiple-Path Particle Dosimetry model was applied to determine if seasonal variation in size-resolved composition influences respiratory deposition patterns. Mg, Al, S, V, Mn, Fe, Ni, Ba, SO4 2-, Na+, and Ca2+ had larger total deposition efficiencies (p < 0.004) during the summer versus the winter in all three regions of the respiratory tract. This trend results from increased relative concentrations of the target analytes per μg m−3 ambient PM1.8 concentration and would be detected with routine PM2.5 filter samples. V, Zn, Se, NO3 -, SO4 2-, and NH4 + also experienced seasonal size distribution shifts that enhanced the specific deposition efficiency in the tracheobronchial and pulmonary regions during the summer months (p < 0.05). This enhanced deposition would not be detected by routine filter samples because all of the size distribution changes occur at particle diameters <2.5 μm. This study demonstrates that changes to the particle size distributions (<2.5 μm) can enhance respiratory deposition efficiencies for trace metals and/or water-soluble ions and this may contribute to seasonal shifts in PM toxicity.

A 17 month climatology of the cloud condensation nuclei number concentration at the high alpine site Jungfraujoch

[1] Between May 2008 and September 2009 the cloud condensation nuclei (CCN) number concentration, NCCN, was measured at the high alpine site Jungfraujoch, which is located in the free troposphere most of the time. Measurements at 10 different supersaturations (0.12%–1.18%) were made using a CCN counter (CCNC). The monthly median NCCN values show a distinct seasonal variability with ∼5–12 times higher values in summer than in winter. The major part of this variation can be explained by the seasonal amplitude of total aerosol number concentration (∼4.5 times higher values in summer), but it is further amplified (factor of ∼1.1–2.6) by a shift of the particle number size distribution toward slightly larger sizes in summer. In contrast to the extensive properties, the monthly median of the critical dry diameter, above which the aerosols activate as CCN, does not show a seasonal cycle (relative standard deviations of the monthly median critical dry diameters at the different supersaturations are 4–9%) or substantial variability (relative standard deviations of individual data points at the different supersaturations are less than 18–37%). The mean CCN-derived hygroscopicity of the aerosol corresponds to a value of the hygroscopicity parameter κ of 0.20 (assuming a surface tension of pure water) with moderate supersaturation dependence. NCCN can be reliably predicted throughout the measurement period with knowledge of the above-mentioned averaged κ value and highly time-resolved (∼5 min) particle number size distribution data. The predicted NCCN was within 0.74 to 1.29 times the measured value during 80% of the time (94,499 data points in total at 10 different supersaturations).

A heuristic examination of cohesive sediment bed exchange in turbulent flows

Prediction of the concentration of suspended cohesive sediment in the marine environment is constrained by difficulties in interpreting experimental evidence on bed exchange, i.e. erosion and deposition of particles, which remains sparse in mechanistic details. In this paper, conditions under which bed exchange in turbulent flows collectively determines the concentration of suspended matter have been examined in the heuristic sense based on selective experimental data. It is argued that interpretation of such data can be significantly facilitated when multi-class representation of particle size, collisional interaction between suspended particles and probabilistic representations of the bed shear stress along with variables describing particle behavior (critical shear stress for deposition, bed floc shear strength) are taken into account. Aggregation—floc growth and breakup kinetics—brings about shifts in the suspended particle size distribution; bed exchange is accordingly modulated and this in turn determines concentration dynamics. Probabilistic representation of the governing variables broadens the suspended sediment size spectrum by increasing the possibilities of inter-particle interactions relative to the mean-value representation. Simple models of bed exchange, which essentially rely on single-size assumption and mean-value representation of variables, overlook the mechanistic basis underpinning particle dynamics.

Interaction of bentonite colloids with Cs, Eu, Th and U in presence of humic acid: A flow field-flow fractionation study

The interaction of Cs(I), Eu(III), Th(IV) and U(VI) with montmorillonite colloids was investigated in natural Grimsel Test Site groundwater over a 3 years period. The asymmetric flow field-flow fractionation combined with various detectors was applied to study size variations of colloids and to monitor colloid association of trace metals. The colloids suspended directly in the low ionic strength ( I), slightly alkaline granitic groundwater ( I = 10 −3 mol/L, pH 9.6) showed a gradual agglomeration with a size distribution shift from initially 10–200 nm to 50–400 nm within over 3 years. The Ca 2+ concentration of 2.1 × 10 −4 mol/L in the ground water is believed to be responsible for the slow agglomeration due to Ca 2+ ion exchange against Li + and Na + at the permanently charged basal clay planes. Furthermore, the Ca 2+ concentration lies close to the critical coagulation concentration (CCC) of 10 −3 mol L −1 for clay colloids. Slow destabilization may delimit clay colloid migration in this specific groundwater over long time scales. Eu(III) and Th(IV) are found predominantly bound to clay colloids, while U(VI) prevails as the UO 2(OH) 3 − complex and Cs(I) remains mainly as aquo ion under our experimental conditions. Speciation calculations qualitatively represent the experimental data. A focus was set on the reversibility of metal ion-colloid binding. Addition of humic acid as a competing ligand induces rapid metal ion dissociation from clay colloids in the case of Eu(III) even after previous aging for about 3 years. Interestingly only partial dissociation occurs in the case of Th(IV). Experiments and calculations prove that the humate complexes dominate the speciation of all metal ions under given conditions. The partial irreversibility of clay bound Th(IV) is presently not understood but might play an important role for the colloid-mediated transport of polyvalent actinides over wide distances in natural groundwater.

How allometric scaling relates to soil abiotics

For most species, the logarithm of their average body mass is negatively related to the logarithm of their relative population density, i.e. the numerical abundance. In this way, the allometric scaling (both mass–abundance regressions and body–size spectra) becomes useful in ecological theory to build and explain food webs. Using empirical evidence derived from 145 Dutch sites, a hypothesis is formulated to explain how soil microbivores, detritivores and predators react to increasing resource availability. Shifts in size distribution, and subsequently changes in soil food‐web structure, are further discussed in the perspective of Holling's sequential interactions between basic system functions. We show that the allometric scaling and the averages of the (log‐transformed) prey:predator body‐mass ratios are reliable predictors for assessing faunal responses to nutrient availability. We view this work as a first attempt toward an extensive comparison of ecological processes in different soil systems.

The collateral network concept: Remodeling of the arterial collateral network after experimental segmental artery sacrifice

A comprehensive strategy to prevent paraplegia after open surgical or endovascular repair of thoracoabdominal aortic aneurysms requires a thorough understanding of the response of the collateral network to extensive segmental artery sacrifice. Ten Yorkshire pigs underwent perfusion with a low-viscosity acrylic resin. With the use of cardiopulmonary bypass, 2 animals each were perfused in the native state and immediately, 6 hours, 24 hours, and 5 days after sacrifice of all segmental arteries (T4-L5). After digestion of surrounding tissue, the vascular cast of the collateral network underwent analysis of arterial and arteriolar diameters and the density and spatial orientation of the vasculature using light and scanning electron microscopy. Within 24 hours, the diameter of the anterior spinal artery had increased significantly, and within 5 days the anterior spinal artery and the epidural arterial network had enlarged in diameter by 80% to 100% (P < .0001). By 5 days, the density of the intramuscular paraspinous vessels had increased (P < .0001), a shift of size distribution from small to larger arterioles was seen (P = .0002), and a significant realignment of arterioles parallel to the spinal cord had occurred (P = .0005). Within 5 days after segmental artery occlusion, profound anatomic alterations in the intraspinal and paraspinous arteries and arterioles occurred, providing the anatomic substrate for preservation of spinal cord blood flow via collateral pathways.

CNS-targeted Viral Delivery of G-CSF in an Animal Model for ALS: Improved Efficacy and Preservation of the Neuromuscular Unit

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by progressive loss of motoneurons. We have recently uncovered a new neurotrophic growth factor, granulocyte-colony stimulating factor (G-CSF), which protects α-motoneurons, improves functional outcome, and increases life expectancy of SOD-1 (G93A) mice when delivered subcutaneously. However, chronic systemic delivery of G-CSF is complicated by elevation of neutrophilic granulocytes. Here, we used adeno-associated virus (AAV) to directly target and confine G-CSF expression to the spinal cord. Whereas intramuscular injection of AAV failed to transduce motoneurons retrogradely, and caused a high systemic load of G-CSF, intraspinal delivery led to a highly specific enrichment of G-CSF in the spinal cord with moderate peripheral effects. Intraspinal delivery improved motor functions, delayed disease progression, and increased survival by 10%, longer than after systemic delivery. Mechanistically, we could show that G-CSF in addition to rescuing motoneurons improved neuromuscular junction (NMJ) integrity and enhanced motor axon regeneration after nerve crush injury. Collectively, our results show that intraspinal delivery improves efficacy of G-CSF treatment in an ALS mouse model while minimizing the systemic load of G-CSF, suggesting a new therapeutic option for ALS treatment.

Nutrient enrichment differentially affects body sizes of primary consumers and predators in a detritus‐based stream

We assessed how a 5‐yr nutrient enrichment affected the responses of different size classes of primary consumers and predators in a detritus‐based headwater stream. We hypothesized that alterations in detritus availability because of enrichment would decrease the abundance and biomass of large‐bodied consumers. In contrast, we found that 2 yr of enrichment increased the biomass and abundance of all consumers regardless of body size. Furthermore, during the fourth and fifth year of enrichment, the abundance and biomass of largebodied primary consumers continued to increase, while small‐bodied primary consumers returned to pretreatment levels. The size structure of a dominant primary consumer (Pycnopsyche spp.) also shifted during the 5‐yr enrichment: its average and maximum individual body size increased in the treatment stream compared with the reference stream. Positive enrichment effects also occurred on small‐bodied predators, but not on large‐bodied predators. Thus, enrichment increased prey body size, but these positive effects on large prey did not propagate up to higher trophic levels to affect large predators. Because consumer body size can be an important species‐specific trait determining population dynamics and ecosystem processes, these observed shifts in consumer size distributions suggest a potentially important pathway for global increases in nutrient enrichment to alter stream structure and function.

On the impacts of phytoplankton-derived organic matter on the properties of the primary marine aerosol – Part 1: Source fluxes

Abstract. The effect of biogenic dissolved and colloidal organic matter on the production of submicron primary sea-spray aerosol was investigated via the simulation of bubble bursting in seawater enriched with phytoplankton-released organics. Seawater samples collected along a transect off the West African coast during the RHaMBLe cruise (RRS Discovery cruise D319), conducted as part of the SOLAS UK program, were analysed in order to identify the dominant oceanic algal species in a region of high biological activity. Cultures of microalgal strains representative of the species found in the collected seawater were grown in order to produce natural bioexudate. Colloidal plus dissolved organic fraction in this material remaining after &lt;0.2 μm filtration was employed to prepare organic-enriched seawater proxies for the laboratory production of marine aerosol using a plunging-waterjet system as an aerosol generator. Submicron size distributions of aerosols generated from different organic monolayers and seawater proxies enriched with biogenic exudate were measured and compared with blanks performed with artificial seawater devoid of marine organics. A shift of the aerosol submicron size distribution toward smaller sizes and an increase in the production of particles with dry diameter (Dp0)&lt;100 nm was repeatedly observed with increasing amounts of diatomaceous bioexudate in the seawater proxies used for aerosol generation. The effect was found to be sensitive to the organic carbon concentration in seawater and the algal exudate type. Diatomaceous exudate with organic carbon concentration (OC&lt;0.2 μm) &gt;175 μM was required to observe a significant impact on the size distribution, which implies that effects are expected to be substantial only in high biological activity areas abundant with diatom algal populations. The laboratory findings were in agreement with analogous bubble-bursting experiments conducted with unfiltered oceanic seawater collected during the RHaMBLe cruise, which revealed a higher production of particles with Dp0&lt;100 nm at regions with high biological activity. These findings suggest that the increase in the atmospheric aerosol modal sizes from winter to summer, reported by long-term observations in North Atlantic waters, is not directly due to an impact of the higher primary organic matter production occurring during warm periods. A novel sub-micrometric size-resolved source flux function, explicitly defined as a function of the diatomaceous exudate concentration, was derived from the size distribution measurements and the estimation of the fractional whitecap coverage. According to the defined parameterisation, a 300 μM OC&lt;0.2 μm concentration of diatomaceous exudate in seawater produces an overall increment in the total source particle flux of ~20% with respect to the organics-free seawater case. The effect increases with decreasing particle size for Dp0&lt;100 nm, resulting in multiplicative factors between 1.02–2 with respect to the particle flux generated from seawater devoid of marine organics. The total source flux derived from the presented parameterisation was compared to recent definitions of sea-spray source fluxes based on laboratory and field observations in the literature.