The contribution of marine organics to the air quality of the western United States

The contribution of marine organic emissions to the air quality in coastal areas of the western United States is studied using the latest version of the US Environmental Protection Agency (EPA) regional-scale Community Multiscale Air Quality (CMAQv4.7) modeling system. Emissions of marine isoprene, monoterpenes, and primary organic matter (POM) from the ocean are implemented into the model to provide a comprehensive view of the connection between ocean biology and atmospheric chemistry and air pollution. Model simulations show that marine organics can increase the concentration of PM<sub>2.5</sub> by 0.1–0.3 μg m<sup>−3</sup> (up to 5%) in some coastal cities such as San Francisco, CA. This increase in the PM<sub>2.5</sub> concentration is primarily attributed to the POM emissions, with small contributions from the marine isoprene and monoterpenes. When marine organic emissions are included, organic carbon (OC) concentrations over the remote ocean are increased by up to 50% (25% in coastal areas), values consistent with recent observational findings. This study is the first to quantify the air quality impacts from marine POM and monoterpenes for the United States, and it highlights the need for inclusion of marine organic emissions in air quality models

Interpreting elevated space-borne HCHO columns over the Mediterranean Sea using the OMI sensor

Formaldehyde (HCHO) is an oxidation product of a wide range of volatile organic compounds (VOCs) and important atmospheric constituent found in both the polluted urban atmosphere and remote background sites. In this study, remotely sensed data of HCHO vertical column densities are analyzed over the Mediterranean Sea using the Ozone Monitoring Instrument (OMI). Data analysis indicates a marked seasonal cycle with a summer maximum and winter minimum confined to the marine environment during a three year period (2005–2007) examined. A possible retrieval artifact associated with Saharan dust transport over the region is explored by changing intensity of Saharan dust sources in GEOS-Chem following the recommendation of Generoso et al. (2008). Recalculated air mass factors (AMF), based on the new values of aerosol loadings, lead to a reduction of the summertime "hot spot" in OMI retrieval of HCHO vertical columns over the Mediterranean Sea; however, even after the correction, enhanced values are still present in this region. To explain these values, marine biogenic sources of VOCs are examined. Calculations indicate that emission of phytoplankton-produced isoprene is not likely to explain the enhanced HCHO vertical columns over the Mediterranean Sea. Model simulations in conjunction with measurements studies may be required to fully explore the complex mechanism of HCHO formation over the Mediterranean and its implications for the air quality in the region

Wind speed dependent size-resolved parameterization for the organic mass fraction of sea spray aerosol

For oceans to be a significant source of primary organic aerosol (POA), sea spray aerosol (SSA) must be highly enriched with organics relative to the bulk seawater. We propose that organic enrichment at the air-sea interface, chemical composition of seawater, and the aerosol size are three main parameters controlling the organic mass fraction of sea spray aerosol (OM<sub>SSA</sub>). To test this hypothesis, we developed a new marine POA emission function based on a conceptual relationship between the organic enrichment at the air-sea interface and surface wind speed. The resulting parameterization is explored using aerosol chemical composition and surface wind speed from Atlantic and Pacific coastal stations, and satellite-derived ocean concentrations of chlorophyll-<i>a</i>, dissolved organic carbon, and particulate organic carbon. Of all the parameters examined, a multi-variable logistic regression revealed that the combination of 10 m wind speed and surface chlorophyll-<i>a</i> concentration ([Chl-<i>a</i>]) are the most consistent predictors of OM<sub>SSA</sub>. This relationship, combined with the published aerosol size dependence of OM<sub>SSA</sub>, resulted in a new parameterization for the organic mass fraction of SSA. Global emissions of marine POA are investigated here by applying this newly-developed relationship to existing sea spray emission functions, satellite-derived [Chl-<i>a</i>], and modeled 10 m winds. Analysis of model simulations shows that global annual submicron marine organic emission associated with sea spray is estimated to be from 2.8 to 5.6 Tg C yr<sup>−1</sup>. This study provides additional evidence that marine primary organic aerosols are a globally significant source of organics in the atmosphere

Model evaluation of marine primary organic aerosol emission schemes

In this study, several marine primary organic aerosol (POA) emission schemes have been evaluated using the GEOS-Chem chemical transport model in order to provide guidance for their implementation in air quality and climate models. These emission schemes, based on varying dependencies of chlorophyll <i>a</i> concentration ([chl <i>a</i>]) and 10 m wind speed (<i>U</i><sub>10</sub>), have large differences in their magnitude, spatial distribution, and seasonality. Model comparison with weekly and monthly mean values of the organic aerosol mass concentration at two coastal sites shows that the source function exclusively related to [chl <i>a</i>] does a better job replicating surface observations. Sensitivity simulations in which the negative <i>U</i><sub>10</sub> and positive [chl <i>a</i>] dependence of the organic mass fraction of sea spray aerosol are enhanced show improved prediction of the seasonality of the marine POA concentrations. A top-down estimate of submicron marine POA emissions based on the parameterization that compares best to the observed weekly and monthly mean values of marine organic aerosol surface concentrations has a global average emission rate of 6.3 Tg yr<sup>−1</sup>. Evaluation of existing marine POA source functions against a case study during which marine POA contributed the major fraction of submicron aerosol mass shows that none of the existing parameterizations are able to reproduce the hourly-averaged observations. Our calculations suggest that in order to capture episodic events and short-term variability in submicron marine POA concentration over the ocean, new source functions need to be developed that are grounded in the physical processes unique to the organic fraction of sea spray aerosol

Antiracism Internship: Applying the Ecological Social Justice School Counseling Theory

This manuscript describes an empirically designed internship course that utilized the Ecological Social Justice School Counseling theory to teach internship students how to engage in antiracist practice to address social determinants of health in schools. The research reports on the eight school counseling internship students\u27 experiences, through five themes and 12 subthemes, highlighting the ways they increased awareness of SDOH, antiracist practice, and related constructs at their schools and with students including their action toward addressing SDOH, advocacy, barriers, and growth. Implications for counselor educators and site supervisors conclude

The Engine Is the Message: Videogame Infrastructure and the Future of Digital Platforms

On January 18, Microsoft revealed its $68.7 billion deal to acquire videogame publisher Activision Blizzard. The acquisition was pitched as an investment towards “metaverse platforms” that gaming would play a key role in developing. Journalists speculated about the increasing consolidation of the videogame industry and whether blockbuster franchises would be locked into Microsoft’s platforms and subscription services. Commentary on the metaverse weighed in on how toxicity and harassment in game industry workplaces such as Activision Blizzard might relate to issues of trust and safety in virtual worlds such as Meta’s Horizon Worlds. Seemingly above the fray of platform strategy, market speculation, and corporate scandal, New Yorker writer Kyle Chayka (2022) tweeted as a matter of fact: “video game infrastructure and tools are increasingly going to take over all digital platforms”. This panel contextualizes discussions about the business and aesthetics of 3D platforms in the infrastructural work of game engines, which routinely integrate databases, file formats, web protocols, and translational algorithms. We trace public debates and corporate statements over representation and governance, equity and inclusion (Bosworth 2021) to the techniques, technologies, and practices that enable massive real-time 3D digital spaces to flow and transact. We also highlight the growing intertwinement between game engine development companies and related content ecosystems, such as the Epic Games Store and the Unreal Engine, and Epic’s and Unity’s Asset Stores. This panel investigates how digital systems are designed to regulate technical interoperability and its implications for creative practice and cultural production. Together, these papers map how power and capital become centralized and distributed throughout the back end of the metaverse, and politicize how social practices and subjectivities are negotiated through technological architecture

Global distribution and climate forcing of marine organic aerosol: 1. Model improvements and evaluation

Marine organic aerosol emissions have been implemented and evaluated within the National Center of Atmospheric Research (NCAR)'s Community Atmosphere Model (CAM5) with the Pacific Northwest National Laboratory's 7-mode Modal Aerosol Module (MAM-7). Emissions of marine primary organic aerosols (POA), phytoplankton-produced isoprene- and monoterpenes-derived secondary organic aerosols (SOA) and methane sulfonate (MS<sup>−</sup>) are shown to affect surface concentrations of organic aerosols in remote marine regions. Global emissions of submicron marine POA is estimated to be 7.9 and 9.4 Tg yr<sup>−1</sup>, for the Gantt et al. (2011) and Vignati et al. (2010) emission parameterizations, respectively. Marine sources of SOA and particulate MS<sup>−</sup> (containing both sulfur and carbon atoms) contribute an additional 0.2 and 5.1 Tg yr<sup>−1</sup>, respectively. Widespread areas over productive waters of the Northern Atlantic, Northern Pacific, and the Southern Ocean show marine-source submicron organic aerosol surface concentrations of 100 ng m<sup>−3</sup>, with values up to 400 ng m<sup>−3</sup> over biologically productive areas. Comparison of long-term surface observations of water insoluble organic matter (WIOM) with POA concentrations from the two emission parameterizations shows that despite revealed discrepancies (often more than a factor of 2), both Gantt et al. (2011) and Vignati et al. (2010) formulations are able to capture the magnitude of marine organic aerosol concentrations, with the Gantt et al. (2011) parameterization attaining better seasonality. Model simulations show that the mixing state of the marine POA can impact the surface number concentration of cloud condensation nuclei (CCN). The largest increases (up to 20%) in CCN (at a supersaturation (<i>S</i>) of 0.2%) number concentration are obtained over biologically productive ocean waters when marine organic aerosol is assumed to be externally mixed with sea-salt. Assuming marine organics are internally-mixed with sea-salt provides diverse results with increases and decreases in the concentration of CCN over different parts of the ocean. The sign of the CCN change due to the addition of marine organics to sea-salt aerosol is determined by the relative significance of the increase in mean modal diameter due to addition of mass, and the decrease in particle hygroscopicity due to compositional changes in marine aerosol. Based on emerging evidence for increased CCN concentration over biologically active surface ocean areas/periods, our study suggests that treatment of sea spray in global climate models (GCMs) as an internal mixture of marine organic aerosols and sea-salt will likely lead to an underestimation in CCN number concentration

THERMAL DENATURATION OF MONOMERIC AND TRIMERIC PHYCOCYANINS STUDIED BY STATIC AND SPECTROSCOPY POLARIZED TIME-RESOLVED FLUORESCENCE

C-Phycocyanin (PC) and allophycocyanin (APC). as well as the a-subunit of PC. have been isolated from the blue-green alga (cyanobacterium). Spirulina platensis. The effects of partial thermal denaturation of PC and of its state of aggregation have been studied by ps time-resolved, polarized fluorescence spectroscopy. All measurements have been performed under low photon fluxes (< 10’ ’ photonsipulse x cm’) to minimize singlet-singlet annihilation processes. A complex decay is obtained under most conditions, which can be fitted satisfactorily with a bi-exponential (7’ = 70400 ps. T? = 1000-3000 ps) for both the isotropic and the polarized part, but with different intensities and time constants for the two decay curves. The data are interpreted in the frameworkof the model first developed by Teak and Dale (Biochern. J. 116, 161 (1970)], which divides the spectroscopically different chromophores in (predominantly) sensitizing (s) and fluorescing U, ones. If one assumes temperature dependent losses in the energy transfer from the s to the f and between f chromophores. both the biexponential nature of the isotropic fluorescence decay and the polarization data can be rationalized. In the isotropic emission (corresponding to the population of excited states) the short lifetime is related to the s-,f transfer. the longer one to the “free“ decay of the final acceptor(s) (= f). The polarized part is dominated by an extremely short decay time. which is related to s+f transfer, as well as to resonance transfer between the f-chromophores