Browsing by Author "Norman, Ann-Lise"
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- ItemOpen AccessAtmospheric Carbon Dioxide Leak Detection from Carbon Capture and Storage Sites(2012-12-20) Mostafavi Pak, Seyedeh Nasrin; Norman, Ann-Lise; Layzell, David B.Carbon Capture and Storage is one of the proposed technologies to reduce anthropogenic carbon dioxide emissions. One of the concerns about the feasibility and safety of this technology is the possible atmospheric leakage of CO2 from geological storage sites. Leakage may intercept shallow aquifers, surface body waters, and escape to the atmosphere, which can be hazardous to both ecosystems and human health. A system was developed in this study for sampling plumes of CO2 and determining whether they are likely to be from a CO2 storage site. Since atmospheric CO2 levels naturally fluctuate due to photosynthesis, respiration, biomass and fossil fuel combustion, elevations in CO2 concentration do not necessarily represent a leakage. It is possible to differentiate between different sources of CO2 by looking at the ratio of O2 depletion to CO2 elevation of a plume relative to the background air (dO2/dCO2). A gas analysis system was used to measure differentials in CO2 and O2 concentrations for different plume samples relative to background air. The CALPUFF dispersion model was used to estimate the location and maximum concentration levels of CO2 in the atmosphere. Then a CO2 leakage from a storage site was simulated by release of pure CO2 with emission rate of about 100 L/min for seven hours at a measurement site. The dO2/dCO2 of the plume samples were measured relative to background air collected at the site. Measured absolute values of dO2/dCO2 for plume samples from pure CO2 emissions (0.23 - 0.31) were significantly different from the measured values for plume samples from combustion of different types of carbon based fuels (1.06 - 1.97).
- ItemOpen AccessCharacterization of Meltwater Chemistry at Haig Glacier, Canadian Rocky Mountains(2018-09-04) Miller, Kristina; Marshall, Shawn; Else, Brent G. T.; Norman, Ann-LiseWith rising temperatures, Alberta’s glaciers are under stresses which alter the timing, amount, and composition of meltwater contributions to rivers flowing from the Rocky Mountains. This study took place on Haig Glacier, located at the headwaters of Kananaskis River, feeding into the Bow River downstream. Hydrochemical analyses were used to partition the runoff into supra and sub-glacial fractions. This study found that at Haig Glacier, water isotopes are not useful for partitioning glacial runoff, and that basal runoff is best identified by sulphate from the bedrock. The basal portion in bulk runoff increased from 5.5% in early July to 10.5% in late August. This study improves knowledge of the glacier’s internal hydrologic pathways and processes during the melt season, as well as the chemical signature of glacier meltwater in the Canadian Rockies, which will serve as a contribution to basin-scale studies in the future.
- ItemOpen AccessChemical Characteristics of Ambient Fine Particles in Calgary(2016) Yu, Kuangyou; Du, Ke; Mohamad, Majeed; Li, Simon; Norman, Ann-LiseAirborne fine particles (PM2.5) play a major role in air quality. This study focuses on the chemical composition of PM2.5 and its seasonal variation in 2015, based on an 8-month observation campaign in Calgary. Elemental carbon, organic carbon, and nine kinds of water-soluble ions were analyzed in this study. PM2.5 samples were collected by URG-3000ABC air sampler and were analyzed by DRI Model 2001A Thermal/Optical Carbon Analyzer and ICS-2500 ion chromatography. The concentration of PM2.5 has demonstrated a significant seasonal variation with an elevated concentration in summer (13±6μg/m3) and low concentration in winter (9±3μg/m3), which is opposite to most previous studies. Most of the water-soluble inorganic ion components have shown opposite variations. Organics were the main chemical components accounting for 59% of PM2.5. Secondary organic carbon accounted for more than 65% of the total organic carbon. Therefore, the seasonal variation of PM2.5 followed the pattern of SOC.
- ItemOpen AccessDifferentiating Diffuse Aurora(2019-12) Grono, Eric M.; Donovan, Eric; Behjat, Laleh; Norman, Ann-Lise; Hobill, David W.; Liemohn, Michael W.Pulsating aurora is a pervasive early morning auroral display. Perhaps because of the awkward viewing hours, it received comparatively little attention in past years and is often discussed as if it is just one phenomenon. However, pulsating aurora can be differentiated into at least three types based on the extent of their pulsation and structuring (Grono and Donovan, 2018). Amorphous pulsating aurora (APA) is characterized by extensive pulsation and a lack of persistent structuring. In contrast, patchy pulsating aurora (PPA) and patchy aurora (PA) features can persist for tens of minutes and follow ionospheric convection (Grono et al., 2017). While PPA structures pulsate over much of their area, PA is mostly non-pulsating. The most common pulsating aurora is APA, which is nearly ubiquitous during the early morning and can appear earlier than PPA and PA (Grono and Donovan, 2019b). Pulsating auroras do not occur poleward of the proton aurora, only within or equatorward of it (Grono and Donovan, 2019a). PPA and PA appear predominantly equatorward of the boundary between stably trapped protons and those scattered by tight magnetic field curvature. This suggests that the processes responsible for the patchiness of PPA and PA are constrained to the mostly dipolar inner magnetosphere. Nishimura et al. (2010) demonstrated that there can be a nearly one-to-one correspondence between plasma wave power and auroral brightness. Consequently, auroral brightness should be able to act as a proxy for wave power, and wave structuring should indicate which type of pulsating aurora a spacecraft is observing. PA should be associated with unmodulated plasma waves persisting for the length of time it takes for a spacecraft to transit the source region of a patch. The location of such wave structuring coincides with where PA occurs (Grono and Donovan, 2019c). Sunrise prevents optical observations of the aurora from continuing past dawn, making it difficult to assess how long pulsating aurora can persist for. However, these plasma wave observations indicate that the processes responsible for PA and PPA structuring may continue into the afternoon.
- ItemOpen AccessDimethyl sulfide and aerosol sulfate in the arctic atmosphere(2011) Rempillo, Ofelia Tampis; Norman, Ann-LiseDimethyl sulfide (DMS) and its oxidation products, which have been proposed to provide a climate feedback mechanism by affecting aerosol and cloud radiative properties, were measured during onboard sampling campaigns in the Arctic in the Fall of 2007 and 2008. DMS concentrations were found to be localized with highly variable concentrations ranging from below detection limit (0.3 nmol/m3) to 14 nmol/m3. DMS flux was calculated based on surface water measurements conducted in open waters and yielded an average of 0.7 ?mol/m2/d along Baffin Bay. DMS oxidation products, sulfur dioxide (SO2) , methane sulfonic acid (MSA), and sulfate (SO/ -) in aerosols were also measured. Concentrations of atmospheric sulfur compounds during the campaign were [SO2] = 2.7- 135 nmol/m3 (2007) and 0.28-27 nmol/m3 (2008), [MSA] = 0.03-0.07 nmol/m3 (2007) and 0.02-0.14 (2008), and non-seasalt sulfate [nSS-So/-] = 0.5-7.0 nmol/m3 (2007) and 0.01-2.0 nmol/m3 (2008). Median daily biogenic SO2 and so/ - concentrations obtained from stable isotope apportionment techniques were found to be approximately 0-105 nmol/m3 and 0-1. 7 nmol/m3 respectively for 2007 and approximately 0-15 nmol/m3 and 0-0.4 nmol/m3 respectively for 2008. Applying conditions for significant new aerosol formation given in Pirjola et al. (1999), the study shows that sufficient biogenic SO2 is released from DMS oxidation to form new aerosols in clean air conditions. Pre-existing aerosols act as an additional condensation sink that prevents new aerosol formation in air parcels polluted by ship stack emissions. These results suggest that the predicted increase in primary productivity and DMS marine emissions could significantly affect the climate regionally. However, an increase in ship traffic would decrease locally the cooling effect of DMS emissions.
- ItemOpen AccessDynamics of Plant Growth; A Theory Based on Riemannian Geometry(2015-12-22) Pulwicki, Julia; Hobill, David; Davidsen, Jörn; Prusinkiewicz, Przemysław; Norman, Ann-Lise; Lines, Larry; Hillen, ThomasIn this work, a new model for macroscopic plant tissue growth based on dynamical Riemannian geometry is presented. We treat 1D and 2D tissues as continuous, deformable, growing geometries for sizes larger than 1mm. The dynamics of the growing tissue are described by a set of coupled tensor equations in non-Euclidean (curved) space. These coupled equations represent a novel feedback mechanism between growth and curvature dynamics. For 1D growth, numerical simulations are compared to two measures of root growth. First, modular growth along the simulated root shows an elongation zone common to many species of plant roots. Second, the relative elemental growth rate (REGR) calculated in silico exhibits temporal dynamics recently characterized in high-resolution root growth studies but which thus far lack a biological hypothesis to explain them. Namely, the REGR can evolve from a single peak localized near the root tip to a double-peak structure. In our model, this is a direct consequence of considering growth as both a geometric reaction-diffusion process and expansion due to a distributed source of new materials. In 2D, we study a circularly symmetric growing disk with emergent negative curvatures. These results are compared against thin disk experiments, which are a proxy model for plant leaves. These results also apply to the curvature evolution and the inhomogeneous growth pattern of the Acetabularia cap. Lastly, we extend the model to anisotropic disks and predict the growth dynamics for a 2D curved surface which develops an elongated shape with localized ruffling. Our model also provides several measures of the dynamics of tissue growth. These include the time evolution of the metric and velocity field, which are dynamical variables in the model, as well as expansion, shear and rotation which are deformation tensors characterizing the growth of the tissue. The latter are physically measurable quantities that remain to be fully explored using modern tissue growth imagining techniques.
- ItemOpen AccessExploring Novel Strategies for Universal Detection in Chromatography(2016) Scott, Andrea Ferelyth; Thurbide, Kevin B.; Hinman, Allen Scott; Langford, Cooper Harold; Norman, Ann-Lise; Murch, Susan JeanThis thesis presents novel strategies for the universal detection of polar analytes in chromatography. This included the further development of a universal detector that is compatible with organic solvents, as well as exploring separation techniques that are compatible with the universal Flame Ionization Detector (FID). For instance, the universal response of the Acoustic Flame Detector (AFD) was comprehensively compared to the FID, where a very close linear correlation (r2 of 0.9103) was found between them. A few minor exceptions were also observed, where the most notable differences occurred for organometallic compounds. Overall, results indicate that the AFD provides a uniform response toward most hydrocarbons that is qualitatively very similar to that of an FID. Interestingly, a novel response mode for alkali metals was also observed in a Subcritical Water Chromatography operating regime. Optimal hydrogen flame gas flow rates were found near 40 mL/min for hydrocarbon response and 80 mL/min for alkali response. KCl, NaCl, LiCl and ethanol each displayed a linear FID response with respective sensitivities of 7500, 980, 130 and 1 mV/µg of analyte. This was subsequently demonstrated to greatly alter the FID response of organic salts. Accordingly, their presence in analytical samples or mobile phases must therefore be accounted for when using this detector. Finally, a novel method of separating polar analytes in Supercritical Fluid Chromatography through dynamically controlling analyte retention by tuning the pH of a water stationary phase is presented. The method utilizes a change in mobile phase from N2 to CO2 to effectively reduce stationary phase pH and control the elution of organic acids from the column. This effect is also observed to be reasonably independent of column length and time. For example in the latter case, at 80oC, a hexanoic acid standard analyte can be readily eluted on demand from a 10 m column by switching to CO2 at any point over a run time of about 1 hour. The N2/CO2 switching system is used to analyze organic acids present in a variety of different samples and it is found that they can be eluted on demand with high selectivity over other matrix components.
- ItemOpen AccessIce Nucleating Particle and Ion Characteristics of Arctic Aerosols(2021-08-22) Henschel, Colleen Leanne; Norman, Ann-Lise; Wieser, Michael; Else, BrentINPs are aerosol particles that allow for the formation of ice crystals in clouds at temperatures warmer than required for homogeneous freezing. These aerosols are particularly important for the formation of mixed-phase clouds, which are ubiquitous during the Arctic summer. In order to better understand the factors affecting the rapidly warming Arctic climate, this study investigates INP concentrations found in size-segregated aerosol, fog and precipitation samples collected in the Arctic during the summer of 2016. The key findings from this study include: (1) the initial droplet freezing temperature correlates with sea salt ion concentrations for fog samples and aerosol samples in the size range of 1.5-7.2µm diameter, (2) INP concentrations for aerosol samples decreased after both heating and filtering, but were still distinguishable from blank samples, indicating the presence of biological INPs and separable ice nucleating components, (3) the INP concentrations measured for co-collected seawater samples were similar overall, but were not consistent at the exact locations of collection, and (4) the important size range of aerosols acting as INPs varied by sample time and location.
- ItemOpen AccessIce Nucleation: Sulfate and Its Influence in Arctic and Rural and Urban NW Continental Precipitation(2019-08-20) Derksen, Mark; Norman, Ann-Lise; Else, Brent G. T.; Hobill, David W.; Wieser, Michael E.With the growth of urban centers and decline of natural ecosystems, the increasing presence of aerosol particles has the potential to have major impacts on climate. This study assessed the ice nucleation characteristics of anthropogenic and organic/biogenic sulfate sources in precipitation samples from the Arctic, Kananaskis (rural continental), and Calgary (Urban continental). Samples were analyzed using droplet freezing technique, isotopic analysis, and anion/cation measurements. Comparisons between deposition-based precipitation sampler and passive fog/rain sampler yielded no significant differences in ice nucleation characteristics. Arctic fog samples had distinct ice nucleating particle characteristics compared to rain and dry deposition samples. A 32% increase in the influence of biogenic matter was apparent in 2016 Arctic samples relative to 2014 samples. The influence of a continental biogenic and/or organic material was apparent in the ice nucleating characteristics of both rural and urban continental samples. Snow samples exhibited the greatest biogenic influence, followed by rain samples, and then dry deposition samples.
- ItemOpen AccessImpacts of Sulfur Dioxide Emissions on Lodgepole Pine Growth in Alberta, Canada(2021-05-14) Earl, Devon; Reid, Mary; Norman, Ann-Lise; Goldblum, David; Layzell, DavidStressors to trees could alter the relationships between climate and tree growth or affect tree growth directly. Anthropogenic emissions of sulfur dioxide (SO2) are one such stressor that may complicate predictions of future tree growth. Sulfur dioxide may affect tree growth and climate-growth relationships directly by entering through stomata and altering photosynthetic rate, or indirectly by causing soil acidification. I assessed how the growth and climate-growth relationships of lodgepole pine (Pinus contorta) changed with varying SO2 emissions intensity and distance from the source in two areas of Alberta, Canada with sour gas facilities. To assess whether SO2 altered tree response to climate, I determined the monthly climate variables (temperature and precipitation) that were important to growth and then assessed how the growth response of trees to these variables changed between periods of differing emissions and proximity to the source of emissions. Overall, climate had a stronger effect on tree growth in the high SO2 emissions period compared to the periods of no emissions and reduced emissions, and farther from the source of emissions compared to near. Liming in stands near the source of emissions likely reduced the effects of SO2 on tree growth and climate-growth relationships in one area. In the case of previous year late summer precipitation, the commonly observed positive effect on tree growth was reversed only during the high emissions period, near the source of emissions. This could indicate that under heavy acidic deposition, increased precipitation may lead to soil nutrient leaching. After accounting for climate, I found that the effect of SO2 emissions on tree growth was complex. In one study area, tree growth near the source of emissions was more strongly negatively affected by 6-year and 10-year cumulative emissions than by annual emissions, indicating that soil acidification may be more important to tree growth than direct effects of SO2 on photosynthesis. SO2 and other stressors to trees should be considered to develop sustainable forestry management practices in the context of a changing climate and in the development of natural climate change mitigation strategies.
- ItemOpen AccessInferences from atmospheric sulphur using stable isotopes over the nw Atlantic(2007) Seguin, Alison Michelle; Norman, Ann-Lise
- ItemOpen AccessIsotope analyses of microgram quantities of sulfur: applications to soil sulfur mineralization studies(1994) Norman, Ann-Lise; Krouse, H. Roy
- ItemOpen AccessModelling long term ice sheet changes to understand the stability of the Greenland Ice Sheet in a warmer world(2020-01-24) Rahimian, Zahra; Marshall, Shawn; Else, Brent G. T.; Norman, Ann-LiseThe Greenland Ice Sheet is under stress with the rising temperature. Ice sheet sensitivity to temperature changes and its contribution to global sea level rise can be estimated using ice sheet/climate models. This study combines an ice dynamics model and an isotope tracer model to carry out long-term coupled ice-sheet/climate simulations to investigate the vulnerability of the Greenland ice sheet to higher temperatures during the Eemian warming. I also examine how Eemian melting may have altered isotopic ratios and temperature reconstructions. The simulations are benchmarked against NEEM and Summit ice core observations to provide validation of model performance. I find that there is ice in central Greenland for climates up to 12ºC higher than present. Greenland’s contribution due to Eemian sea level most likely ranges between 2.8 to 4.3 m, associated with temperature anomalies from 5 to 9ºC. Melt-induced isotopic modifications can cause overestimation of 0.1-2ºC warming in proxy records.
- ItemOpen AccessNovel Strategies for Organosulfur Analysis in Gas Chromatography with Flame Photometric Detection(2020-04-09) McKelvie, Kaylan Halcyon; Thurbide, Kevin B.; Gailer, Jürgen G.; Marriott, Robert A.; Ling, Changchun; Norman, Ann-Lise; Harynuk, James J.This thesis describes the development of novel methods to analyze organosulfur compounds using gas chromatography (GC) with flame photometric detection (FPD). The first area of exploration utilizes a water stationary phase for sulfur separations. Several organosulfur compounds are retained to varying degrees on this phase, while non-polar hydrocarbons are unretained. This prevents the co-elution of sulfur analytes with hydrocarbons and the response quenching that is often observed in GC-FPD. Overall, the water stationary phase is shown to be a useful alternative for the analysis of organosulfur compounds in complex matrices. Next, a sample preparation method using lead oxide particles or plumbite solution is demonstrated to complex thiols into a solid lead thiolate moiety that can be physically separated from complex sample matrices and then reconstituted as the original thiol in a simple replacement solvent for analysis. The method allows thiols to be selectively isolated from co-eluting peaks, which can simplify their determination and greatly reduce interference from signal quenching when using an FPD. As an extension of this technique, a selective chromatographic system is also demonstrated. This uses PbO or plumbite as a pre-column trap for thiols, which allows non-thiols to separate as normal while thiols are not eluted until in situ reconstitution. This illustrates the potential for their controlled GC analysis. Accordingly, results indicate that these methods could be useful alternative approaches for the selective analysis of such thiol-containing samples. Lastly, a novel miniaturized GC-FPD device built within a titanium platform (Ti µGC-FPD) is presented. The monolithic Ti device contains both a separation column and a shielded cavity to house the detector flame. The FPD employs a micro counter-current flame that is stabilized by opposing relatively low flows of oxygen and hydrogen, with minimum detectable limits of about 70 pg S/s for sulfur and 8 pg P/s for phosphorous. Overall, good separations with stable and sensitive detector performance are obtained with the device, and its sturdy Ti structure supports robust operation. Results indicate that this Ti µGC-FPD device may be a useful alternative approach for incorporating selective FPD sensing in µGC analyses.
- ItemOpen AccessS and b isotope variations to track air pollutant deposition in the Castle River of southern Alberta, Canada(2010) Xie, John Guanhua; Norman, Ann-Lise; Wieser, Michael
- ItemOpen AccessSeasonal Pattern and Sources of Particulate Carbon in Kananaskis and Calgary, Alberta(2018-05-18) Ge, Chenqi; Norman, Ann-Lise; Reuten, Christian; Du, Ke; Thurbide, Kevin B.Sources, seasonal pattern of elemental carbon(EC), organic carbon(OC), and total carbon from dry deposition and precipitation in Kananaskis and Calgary were assessed using thermo-optical methods. Vehicle exhaust was inferred to be dominant source of carbon throughout the year with an identical OC/EC of 22±14 in Calgary and 22±5 in Kananaskis in dry deposition. Biogenic OC signal was absent in Kananaskis in precipitation or dry deposition. Biomass burning, with a lower OC/EC both in winter and summer, was potentially associated with recreation and tourism in Kananaskis. Sources from long-range transport impact both locations simultaneously. A lower boundary layer at night concentrates TC and a higher boundary layer in the day lower the concentration in both locations. OC is much more easily removed by precipitation than EC due to is larger surface area and size and OC/EC ratios in precipitation reaching 130 were observed in Calgary while those in Kananaskis reached 46.
- ItemOpen AccessSeasonal patterns and spatial variations of snowpack sulphate isotopes of the Prince of Wales Icefield, Ellesmere Island(2006) Wasiuta, Vivian Leah; Marshall, Shawn J.; Norman, Ann-Lise
- ItemOpen AccessSources and processes affecting atmospheric sulfur at the onset of Arctic winter(2012-09-13) Seguin, Alison Michelle; Norman, Ann-LiseArctic size segregated aerosols and SO2 concentrations were measured at two sites at the onset of winter in 2007 and 2008. Concentrations of non sea salt sulfate are within the same range as previous studies in the Arctic. Apportionment with tracer ions and isotopes were used to distinguish between biogenic sulfur and sulfur from other sources including sea salt, anthropogenic and two local Arctic sources; the Smoking Hills and frost flowers. A method to quantitatively differentiate between frost flower and sea salt sulfate using isotope analysis and constrained frost flower ratios is introduced. This is the first time contributions from frost flower in aerosols are reported quantitatively and reached a maximum of 2.3 nmol/m³. Fine aerosol anthropogenic sulfate concentrations were similar between the sites (Alert 0.8 ± 0.6 nmol/m³; Amundsen 0.3 ± 0.4 nmol/m³) and increased with the onset of winter. Ammonium, nitrate and non sea salt potassium correlated with anthropogenic sulfate at both locations. A strong relationship between anthropogenic sulfate and a deficit in aerosol chloride at Alert, Nunavut supports acidification of aerosols from long range transport in the Arctic fall. The first simultaneous measurements of dimethylsulfide (DMS), biogenic SO2, aerosol methanesulfonic acid (MSA) and biogenic sulfate in the Arctic were carried out. Median biogenic SO2 concentration was 0.07 nmol/m³. MSA concentrations decreased with the onset of winter. A median lifetime of 6.1 days for DMS during the sampling period was modeled. Measured MSA branching ratios (median values at Alert = 0.24; Amundsen = 0.28) were compared to ratios predicted by a DMS oxidation model and were found to be similar when modeled halogen and aqueous oxidation was low. DMS oxidation by NO3∙ is expected to be the largest contribution to DMS oxidation in the Arctic fall. A DMS transport model predicts the region around the Amundsen during the campaign was a net source of DMS (median net transport out of the region =10 nmol m-3 day-1) although the area at times acted as a sink. A net source of DMS from Arctic waters supports that sulfur chemistry in the Arctic is representative of regional and not local conditions.
- ItemOpen AccessStable isotope studies of atmospheric sulphur: comparison of Alberta, Canada and Bermuda(1991) Norman, Ann-Lise; Krouse, H. Roy
- ItemOpen AccessStudy of Dimethyl sulfide, Sulfate Aerosols and Ice Nucleation Particles in the Arctic Summer(2016) Ghahremaninezhadgharelar, Roghayeh; Norman, Ann-Lise; Reuten, Christian; Smith, Wendy LaniAerosols drive significant radiative forcing and affect Arctic climate. Despite the importance of these aerosols in Arctic climate change, there are some key uncertainties in the estimation of their effects and sources. Size-segregated aerosol, SO2 and precipitation samples were collected on board the Canadian Coast Guard Ship Amundsen in the Arctic during July 2014, to utilize the isotopic composition of sulfate to address the contribution of anthropogenic, biogenic and sea salt sources in formation/growth of aerosol. More than 63% of the average sulfate concentration in the fine aerosols (<0.49 μm) was from biogenic sources. For most samples, δ34S values for SO2 and fine aerosols were similar, suggesting gas-to-particle conversion. δ34S apportionment for precipitation samples suggested a relatively low contribution of the biogenic sulfate source (14±8%) and high contribution of sea salt (82±10%). Also, the size distribution of ice nucleation particles (INPs) in the immersion mode was determined for solid particles smaller than 0.45 μm and soluble aerosol in the size range of 0.49-7.2 μm. Large particles (3.0-7.2 μm), were more efficient INPs. In addition, vertical distributions of atmospheric dimethyl sulfide were sampled aboard the research aircraft Polar 6 near Lancaster Sound in July 2014 and on pan-Arctic flights in April 2015. Larger mean DMS mixing ratios were present during April 2015 (campaign-mean of 116±8 pptv) than July 2014 (campaign-mean of 20±6 pptv). A strong decrease was observed in DMS mixing ratios with altitude in July 2014. In contrast, DMS mixing ratios sampled in April 2015 exhibited a relatively more uniform campaign-mean vertical profile and increased with altitude on some flights. These results highlight the role of open water below the flight as the source of DMS during July 2014, and the influence of long-range transport of DMS from further afield in the Arctic during April 2015. In general, the high biogenic fraction of sulfate fine aerosol and relatively high DMS mixing ratios emphasize the role of marine organisms in the formation of fine particles above the Arctic Ocean during July. More investigations are required to find the role of biogenic aerosols in formation of INPs in the Arctic atmosphere.