Total particulate trace element concentrations from bulk aerosol samples collected during the US GEOTRACES EPZT section cruise (R/V Thomas G. Thompson TN303) in the Eastern Tropical Pacific from October to December 2013

Dataset: Total Particulate AerosolsAtmospheric input is important to the biogeochemical cycling of trace metals in the ocean. This dataset provides total particulate trace metal values from bulk aerosols over the Equatorial Pacific along the US GEOTRACES EPTZ transect (TN303) from Peru to Tahiti. This region is characterized as one of the lowest atmospheric deposition regimes in the ocean. Bulk aerosols were collected from the boundary layer (~15 m above sea level) using a high-volume aerosol sampler drawing approximately 1.2 cubic meters of air per minute over Whatman 41 ash-less filter discs. Despite low aerosol loadings, triplicate agreement for most samples was good for Al, Ti, V, Mn, Fe, and Cu. Away from the coast, Cd and Pb values in most samples were close to, or below detection limit. Total digestions were carried out with a combination of hydrochloric acid, nitric acid, hydrofluoric acid, heat and pressure. Total particulate trace metal concentrations were determined at the University of Alaska Fairbanks by inductively couple plasma mass spectrometry (Thermo Element-2) using external calibration curves. For a complete list of measurements, refer to the supplemental document 'Field_names.pdf', and a full dataset description is included in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: http://www.bco-dmo.org/dataset/675632NSF Division of Ocean Sciences (NSF OCE) OCE-1234417, NSF Division of Ocean Sciences (NSF OCE) OCE-145436

Global estimates of mineral dust aerosol iron and aluminum solubility that account for particle size using diffusion-controlled and surface-area-controlled approximations

Mineral aerosol deposition is recognized as the dominant source of iron to the open ocean and the solubility of iron in the dust aerosol is highly variable, with measurements ranging from 0.01–80%. Global models have difficulty capturing the observed variations in solubility, and have ignored the solubility dependence on aerosol size. We introduce two idealized physical models to estimate the size dependence of mineral aerosol solubility: a diffusion‐controlled model and a surface‐area‐controlled model. These models produce differing time‐ and space‐varying solubility maps for aerosol Fe and Al given the dust age at deposition, size‐resolved dust entrainment fields, and the aerosol acidity. The resulting soluble iron deposition fluxes are substantially different, and more realistic, than a globally uniform solubility approximation. The surface‐area‐controlled solubility varies more than the diffusion‐controlled solubility and better captures the spatial pattern of observed solubility in the Atlantic. However, neither of these two models explains the large solubility variation observed in the Pacific. We then examine the impacts of spatially variable, size‐dependent solubility on marine biogeochemistry with the Biogeochemical Elemental Cycling (BEC) ocean model by comparing the modeled surface ocean dissolved Fe and Al with observations. The diffusion‐based variable solubility does not significantly improve the simulation of dissolved Fe relative to a 5% globally uniform solubility, while the surface‐area‐based variable solubility improves the simulation in the North Atlantic but worsens it in the Pacific and Indian Oceans

Acetic acid leachable trace metals from bulk aerosol samples collected during the US GEOTRACES EPZT section cruise (R/V Thomas G. Thompson TN303) in the Eastern Tropical Pacific from October to December 2013

Dataset: Acetic Acid Leachable Trace Metals from AerosolsAtmospheric input is important to the biogeochemical cycling of trace metals in the ocean. The fraction of aerosol trace metals that can potentially dissolve after deposition is of interest for improving knowledge of aerosol/surface ocean interactions. This dataset provides acetic acid leachable trace metal values from bulk aerosol from the Equatorial Pacific along the US GEOTRACES EPTZ transect (TN303) from Peru to Tahiti. This region is characterized as one of the lowest atmospheric deposition regimes in the ocean. Bulk aerosols were collected from the boundary layer (~15 m above sea level) using a high-volume aerosol sampler drawing approximately 1.2 cubic meters of air per minute over Whatman 41 ash-less filter discs. Despite low aerosol loadings, triplicate agreement for most samples was good for Al, Ti, V, Mn, Fe, and Cu. Away from the coast, Cd and Pb values in most samples were close to, or below detection limit. Acetic acid leaches were carried out with a combination of 25% acetic acid and a reducing agent. Leachable trace metal concentrations were determined at the University of Alaska Fairbanks by inductively couple plasma mass spectrometry (Thermo Element-2) using external calibration curves. The aerosol trace metal fractional solubility was calculated as a percent of the total bulk aerosol data from the same cruise (https://www.bco-dmo.org/dataset/675632). For a complete list of measurements, refer to the supplemental document 'Field_names.pdf', and a full dataset description is included in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: http://www.bco-dmo.org/dataset/709276NSF Division of Ocean Sciences (NSF OCE) OCE-1234417, NSF Division of Ocean Sciences (NSF OCE) OCE-145436

Transdisciplinary learning: Transformative collaborations between students, industry, academia and communities.

Background and objectives of the case An analogy: Imagine you are invited to a dinner party, but instead of a stuffy sit-down affair, your host asks you to bring your favourite ingredient, and together you prepare a delicious feast of unique and distinct flavours. UTS’s transdisciplinary initiatives are changing the shape of higher education and forging innovative partnerships by bringing together diverse professional fields. With a focus on practice-based and problem-focused learning, UTS educational programs combine the strengths of multiple disciplines, industries, public sector organisations, and the community to turn real-world problems into rewarding opportunities for education and also “learning for a lifetime”. In place of the limitations of artificial disciplinary boundaries, transdisciplinary learning practices create synergistic and innovative approaches to grappling with complex applied challenges. Students, researchers, practitioners, community members and other stakeholders combine their knowledge, tools, techniques, methods, theories, concepts, as well as cultural and personal perspectives. By understanding problems holistically, the solutions that emerge are bold, innovative, and creative, as well as mutually beneficial. We view this as the future of education: good to work with, and good to think with — problem solving for (and with) industry and society. The Faculty of Transdisciplinary Innovation is re-imagining how education, research, and professional practice can work together to navigate today’s complex problems, and create commercially attractive and socially responsible futures. We also practice what we preach: for example, staff professional development to enact these models in our own teaching; educational programs to provide experiential learning around problem solving within a rapidly-changing environment involving students from across different disciplines and cultural backgrounds; as well as policy development and research on today’s pressing “wicked problems” with industry and government. Primary objectives of this next practice concept of transdisciplinary learning, include: - To promote a shift in industry-university engagement from producing “knowledge for society” to co-generating “knowledge with society”; - To build a resilient ecosystem for co-learning; - To create and sustain future-oriented degree programs with collaboration between industry, government, and community at the centre, geared to prepare our graduates for the complex challenges of a networked world; - To create an agile and responsive industry-university lab environment for generating and testing new experimental models; - To enable industry – by collaborating with our students and academics – to see their problems from a fresh perspective, often through different and revealing lenses, and to notice opportunities and spot challenges that may have otherwise been overlooked; - To prepare students to lead innovation in a rapidly-changing and challenging world; and - To graduate students who are ‘complexity-fluent’, systems thinkers, creative problem-posers and -solvers, and imaginative, ethical citizens

Does Sea Spray Aerosol Contribute Significantly To Aerosol Trace Element Loading? A Case Study From the U.S. GEOTRACES Pacific Meridional Transect (GP15)

Atmospheric deposition represents a major input for micronutrient trace elements (TEs) to the surface ocean and is often quantified indirectly through measurements of aerosol TE concentrations. Sea spray aerosol (SSA) dominates aerosol mass concentration over much of the global ocean, but few studies have assessed its contribution to aerosol TE loading, which could result in overestimates of “new” TE inputs. Low-mineral aerosol concentrations measured during the U.S. GEOTRACES Pacific Meridional Transect (GP15; 152°W, 56°N to 20°S), along with concurrent towfish sampling of surface seawater, provided an opportunity to investigate this aspect of TE biogeochemical cycling. Central Pacific Ocean surface seawater Al, V, Mn, Fe, Co, Ni, Cu, Zn, and Pb concentrations were combined with aerosol Na data to calculate a “recycled” SSA contribution to aerosol TE loading. Only vanadium was calculated to have a SSA contribution averaging \u3e1% along the transect (mean of 1.5%). We derive scaling factors from previous studies on TE enrichments in the sea surface microlayer and in freshly produced SSA to assess the broader potential for SSA contributions to aerosol TE loading. Maximum applied scaling factors suggest that SSA could contribute significantly to the aerosol loading of some elements (notably V, Cu, and Pb), while for others (e.g., Fe and Al), SSA contributions largely remaine

Methods for the sampling and analysis of marine aerosols: results from the 2008 GEOTRACES aerosol intercalibration experiment

Atmospheric deposition of trace elements and isotopes (TEI) is an important source of trace metals to the open ocean, impacting TEI budgets and distributions, stimulating oceanic primary productivity, and influencing biological community structure and function. Thus, accurate sampling of aerosol TEIs is a vital component of ongoing GEOTRACES cruises, and standardized aerosol TEI sampling and analysis procedures allow the comparison of data from different sites and investigators. Here, we report the results of an aerosol analysis intercalibration study by seventeen laboratories for select GEOTRACES-relevant aerosol species (Al, Fe, Ti, V, Zn, Pb, Hg, NO3-, and SO42-) for samples collected in September 2008. The collection equipment and filter substrates are appropriate for the GEOTRACES program, as evidenced by low blanks and detection limits relative to analyte concentrations. Analysis of bulk aerosol sample replicates were in better agreement when the processing protocol was constrained (+/- 9% RSD or better on replicate analyses by a single lab, n = 7) than when it was not (generally 20% RSD or worse among laboratories using different methodologies), suggesting that the observed variability was mainly due to methodological differences rather than sample heterogeneity. Much greater variability was observed for fractional solubility of aerosol trace elements and major anions, due to differing extraction methods. Accuracy is difficult to establish without an SRM representative of aerosols, and we are developing an SRM for this purpose. Based on these findings, we provide recommendations for the GEOTRACES program to and macro-nutrients to the open ocean (Okin et al. 2011) and is a key component of the international GEOTRACES program (GEOTRACES Planning Group 2006). A priority of the GEOTRACES program is to quantify both major and trace elements (e. g., Al, Fe, Ti, V, Zn, Pb, and Hg) and species such as nitrate and sulfate in marine aerosols. Therefore, marine aerosol samples collected during GEOTRACES cruises must follow sampling protocols that permit the collection and analysis of as many elements and compounds as possible, while meeting the constraints associated with basin-wide oceanographic cruises (e. g., space limitations, high-frequency sampling, etc.)

Pyrogenic iron: The missing link to high iron solubility in aerosols

Atmospheric deposition is a source of potentially bioavailable iron (Fe) and thus can partially control biological productivity in large parts of the ocean. However, the explanation of observed high aerosol Fe solubility compared to that in soil particles is still controversial, as several hypotheses have been proposed to explain this observation. Here, a statistical analysis of aerosol Fe solubility estimated from four models and observations compiled from multiple field campaigns suggests that pyrogenic aerosols are the main sources of aerosols with high Fe solubility at low concentration. Additionally, we find that field data over the Southern Ocean display a much wider range in aerosol Fe solubility compared to the models, which indicate an underestimation of labile Fe concentrations by a factor of 15. These findings suggest that pyrogenic Fe-containing aerosols are important sources of atmospheric bioavailable Fe to the open ocean and crucial for predicting anthropogenic perturbations to marine productivity

Evaluation of labile iron processing in atmospheric models

Conference abstract (August 13-18, 2017. Goldschmidt 2017 in Paris, France

The GESAMP global model intercomparison: Evaluation of labile iron in aerosols

Oral session abstract EGU2018-2243, European Geosciences Union (EGU) General Assembly 2018 (8-13 April, 2018, Vienna, Austria

Evaluation of labile iron formation in the atmosphere

Atmospheric deposition of labile iron (Fe) to the ocean has been suggested to modulate primary ocean productivity and thus indirectly affect the climate. A key process contributing to atmospheric sources of labile Fe is associated with atmospheric acidity, which leads to Fe transformation from insoluble to soluble forms. Significant progress has been made in our understanding of atmospheric inputs of labile Fe from natural and anthropogenic sources to the oceans. However, there are still large uncertainties regarding the relative importance of different sources of Fe and effects of atmospheric processing on the bioavailability of the delivered Fe. Here, we investigate the effects of atmospheric processing on Fe solubility and contribution of different sources of Fe to labile Fe in the atmosphere. We compiled Fe loading and solubility in aerosols from four atmospheric chemistry transport models and a number of field measurements. Fe-containing aerosols from combustion sources are characterized by low loading and high solubility, compared to mineral dust. Therefore, labile Fe loading may be separately attributed to combustion and dust aerosols, assuming their distinct emission sources and atmospheric processes. The results suggest that combustion aerosols substantially contribute to labile Fe loading measured in the atmosphere. Thus, assessments of dust-borne Fe fertilization of the oceans should include Fe-containing mineral aerosols affected by combustion sources.Poster presented at Ocean Sciences Meeting 2018, AGU, ASLO, the Oceanography Society. Portland, Oregon, Feb. 11-16, 201