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Effect of demand-controlled ventilation strategies on indoor air pollutants in a classroom: A Norwegian case study

Yang, Aileen; Andersen, Kamilla Heimar; Hak, Claudia; Mikoviny, Tomas; Wisthaler, Armin; Holøs, Sverre Bjørn

IOP Publishing

2023

Retrieval of Aerosol Optical Properties via an All-Sky Imager and Machine Learning: Uncertainty in Direct Normal Irradiance Estimations

Logothetis, Stavros-Andreas; Giannaklis, Christos-Panagiotis; Salamalikis, Vasileios; Tzoumanikas, Panagiotis; Raptis, Panagiotis-Ioannis; Amiridis, Vassilis; Eleftheratos, Kostas; Kazantzidis, Andreas

Quality-assured aerosol optical properties (AOP) with high spatiotemporal resolution are vital for the accurate estimation of direct aerosol radiative forcing and solar irradiance under clear skies. In this study, the sky information from an all-sky imager (ASI) is used with machine learning (ML) synergy to estimate aerosol optical depth (AOD) and the Ångström Exponent (AE). The retrieved AODs (AE) revealed good accuracy, with a dispersion error lower than 0.07 (0.15). The retrieved ML AOPs are used to estimate the DNI by applying radiative transfer modeling. The estimated ML DNI calculations revealed adequate accuracy to reproduce reference measurements with relatively low uncertainties.

2023

PM2.5 Retrieval Using Aerosol Optical Depth, Meteorological Variables, and Artificial Intelligence

Logothetis, Stavros-Andreas; Kosmopoulos, Georgios; Salamalikis, Vasileios; Kazantzidis, Andreas

Particulate matter (PM) is one of the major air pollutants that has adverse impacts on human health. The aim of this study is to present an alternative approach for retrieving fine PM (particles with an aerodynamic diameter less than 2.5 μm, PM2.5) using artificial intelligence. Ground-based instruments, including a hand-held Microtops II sun photometer (for aerosol optical depth), a PurpleAir sensor (for PM2.5), and Rotronic sensors (for temperature and relative humidity), are used for the machine learning algorithm training. The retrieved PM2.5 reveals an adequate performance with an error of 0.08 μg m−3 and a Pearson correlation coefficient of 0.84.

2023

Impact of Aerosol Optical Properties, Precipitable Water, and Solar Geometry on Sky Radiances Using Radiative Transfer Modeling

Giannaklis, Christos-Panagiotis; Logothetis, Stavros-Andreas; Salamalikis, Vasileios; Tzoumanikas, Panagiotis; Kazantzidis, Andreas

Radiative transfer modeling is used to investigate the effect of aerosol optical properties and water vapor on cloud-free sky radiances at various atmospheric conditions. Simulations are generated by changing the most critical aerosol optical properties, namely aerosol optical depth, Ångström exponent, the single-scattering albedo, the precipitable water, and the solar zenith angle (SZA) in three different spectral ranges: ultraviolet A, visible, and near-infrared.

2023

Simulations of Sky Radiances in Red and Blue Channels at Various Aerosol Conditions Using Radiative Transfer Modeling

Giannaklis, Christos-Panagiotis; Logothetis, Stavros-Andreas; Salamalikis, Vasileios; Tzoumanikas, Panagiotis; Katsidimas, Konstantinos; Kazantzidis, Andreas

We conducted a theoretical analysis of the relationship between red-to-blue (RBR) color intensities and aerosol optical properties. RBR values are obtained by radiative transfer simulations of diffuse sky radiances. Changes in atmospheric aerosol concentration (parametrized by aerosol optical depth, AOD), particle’s size distribution (parametrized by Ångström exponent, AE) and aerosols’ scattering (parametrized by single scattering albedo—SSA) lead to variability in sky radiances and, thus, affect the RBR ratio. RBR is highly sensitive to AOD as high aerosol load in the atmosphere causes high RBR. AE seems to strongly affect the RBR, while SSA effect the RBR, but not to such a great extent.

2023

Decreasing trends of ammonia emissions over Europe seen from remote sensing and inverse modelling

Tichý, Ondřej; Eckhardt, Sabine; Balkanski, Yves; Hauglustaine, Didier; Evangeliou, Nikolaos

Ammonia (NH3), a significant precursor of particulate matter, affects not only biodiversity, ecosystems, and soil acidification but also climate and human health. In addition, its concentrations are constantly rising due to increasing feeding needs and the large use of fertilization and animal farming. Despite the significance of ammonia, its emissions are associated with large uncertainties, while its atmospheric abundance is difficult to measure. Nowadays, satellite products can effectively measure ammonia with low uncertainty and a global coverage. Here, we use satellite observations of column ammonia in combination with an inversion algorithm to derive ammonia emissions with a high resolution over Europe for the period 2013–2020. Ammonia emissions peak in northern Europe due to agricultural application and livestock management, in western Europe (industrial activity), and over Spain (pig farming). Emissions have decreased by −26 % since 2013 (from 5431 Gg in 2013 to 3994 Gg in 2020), showing that the abatement strategies adopted by the European Union have been very efficient. The slight increase (+4.4 %) in 2015 is also reproduced here and is attributed to some European countries exceeding annual emission targets. Ammonia emissions are low in winter (286 Gg) and peak in summer (563 Gg) and are dominated by the temperature-dependent volatilization of ammonia from the soil. The largest emission decreases were observed in central and eastern Europe (−38 %) and in western Europe (−37 %), while smaller decreases were recorded in northern (−17 %) and southern Europe (−7.6 %). When complemented with ground observations, modelled concentrations using the posterior emissions showed improved statistics, also following the observed seasonal trends. The posterior emissions presented here also agree well with respective estimates reported in the literature and inferred from bottom-up and top-down methodologies. These results indicate that satellite measurements combined with inverse algorithms constitute a robust tool for emission estimates and can infer the evolution of ammonia emissions over large timescales.

2023

Opinion of the Scientific Committee on health, environmental and emerging risks on the safety of titanium dioxide in toys

Bodin, Laurent; Dusinska, Maria; Stepnik, Maciej; Wijnhoven, Susan; Autrup, Herman; von Goetz, Natalie; Vermeire, Theo G.; Hoet, Peter; Ion, Rodica Mariana; Krätke, Renate; Proykova, Ana; Scott, Marian; de Jong, Wim H.

The Opinion of the Scientific Committee on Health, Environmental and Emerging Risks advises the European Commission on whether the uses of titanium dioxide in toys and toy materials can be considered to be safe in light of the identified exposure, and the classification of titanium dioxide as carcinogenic category 2 after inhalation. Four toy products including casting kits, chalk, powder paints and white colour pencils containing various amounts of TiO2 as colouring agent were evaluated for inhalation risks. For the oral route, childrens’ lip gloss/lipstick, finger paint and white colour pencils were evaluated.

When it can be demonstrated with high certainty that no ultrafine fraction is present in pigmentary TiO2 preparations used in toys and toy materials, safe use with no or negligible risk for all products considered is indicated based on the exposure estimations of this Opinion. However, if an ultrafine fraction is assumed to be present, safe use is not indicated, except for white colour pencils.

Elsevier

2024

Enhanced electrochemical activity of boron-doped nanocarbon functionalized reticulated vitreous carbon structures for water treatment applications

Kaczmarzyk, Iwona; Banasiak, Mariusz; Jakobczyk, Pawel; Sobaszek, Michał Sobaszek; Strugala, Gabriel; Seramak, Tomasz; Rostkowski, Pawel; Karczewski, Jakub; Sawczak, Mirosław; Ryl, Jacek; Bogdanowicz, Robert

An extraordinary charge transfer kinetics and chemical stability make a boron-doped diamond (BDD) a promising material for electrochemical applications including wastewater treatment. Yet, with flat geometrical surfaces its scaling options are limited. In this study, the reticulated Vitreous Carbon (RVC) served as a substrate for boron-doped diamondized nanocarbons (BDNC) film growth resulting with complex heterogeneity carbon structures with different morphologies defined by using electron microscopy, microtomography, activation energy studies, and Raman spectroscopy.

The proposed modification significantly boosted the electrochemical Fe(CN)63−/4− redox activity. The voltammetry and impedimetric studies revealed its origin as a significantly higher share of electrochemically active sites at the BDNC@RVC electrode (increased by 114 %) combined with enhanced heterogeneous rate constant (2× increase up to 8.24·10−4 cm s−1). Finally, to establish its applicability for water treatment, the BDNC@RVC was studied as the anode in electrochemical paracetamol decomposition. Boron-enriched nanoarchitecture formed at the RVC electrode surface substantially reduced the oxidation energy barrier manifested as a decrease in activation overpotential by 212 mV, which gave a consequence in a 78 % removal rate (in 4 h, at 0.7 mA cm−2), 12 % higher than bare RVC and yielding lower amounts of APAP decomposition intermediates.

2024

Aerosol and dynamical contributions to cloud droplet formation in Arctic low-level clouds

Motos, Ghislain; Freitas, Gabriel; Georgakaki, Paraskevi; Wieder, Jörg; Li, Guangyu; Aas, Wenche; Lunder, Chris Rene; Krejci, Radovan; Pasquier, Julie Thérèse; Henneberger, Jan; David, Robert Oscar; Ritter, Christoph; Mohr, Claudia; Zieger, Paul; Nenes, Athanasios

2023

Analysis of nitro- and oxy-PAH emissions from a pilot scale silicon process with flue gas recirculation

Arnesen, Kamilla; Andersen, Vegar; Jakovljevic, Katarina; Enge, Ellen Katrin; Gaertner, Heiko; Aarhaug, Thor Anders; Einarsrud, Kristian Etienne; Tranell, Maria Gabriella

Silicon alloys are produced by carbothermic reduction of quartz in a submerged arc furnace. This high-temperature pyrolytic process is a source of polycyclic aromatic hydrocarbons (PAHs), which are a group of aromatic organic molecules with known mutagenic and carcinogenic properties. In this study, the emission of oxy- and nitro-PAHs from a pilot-scale Si furnace, with varying process conditions such as oxygen level, flue gas recirculation (FGR), and off-gas flow, was investigated. Analysis shows the presence of both oxy- and nitro-PAH species in all experiments, believed to be formed from radical-induced substitution reactions initiated by SiO combustion and NOx formation. During Si production without FGR, the levels of oxy- and nitro-PAHs range between 1.1 and 4.4 μg Nm−3, independent of the flue gas flow rate. With increasing FGR (0–82.5%) and decreasing oxygen level (20.7–13.3%), the concentrations of both oxy- and nitro-PAHs increase to 36.6 and 65.9 μg Nm−3, respectively. When the levels of substituted PAHs increase, species such as 4-nitropyrene and 1,2-benzanthraquinone are in abundance compared to their parent PAHs. Experiments at lower flue gas flow (500 Nm3 h−1 versus 1000 Nm3 h−1) generally produce less substituted PAHs, as well as SiO2 particulate matter and NOx, where the latter two parameters have a 99% correlation in this study.

Royal Society of Chemistry (RSC)

2023

Equilibrium Climate after Spectral and Bolometric Irradiance Reduction in Grand Solar Minimum Simulations

Tartaglione, Nazario; Toniazzo, Thomas; Otterå, Odd Helge; Orsolini, Yvan Joseph Georges Emile G.

In this study, we use the Whole Atmosphere Community Climate Model, forced by present-day atmospheric composition and coupled to a Slab Ocean Model, to simulate the state of the climate under grand solar minimum forcing scenarios. Idealized experiments prescribe time-invariant solar irradiance reductions that are either uniform (percentage-wise) across the total solar radiation spectrum (TOTC) or spectrally localized in the ultraviolet (UV) band (SCUV). We compare the equilibrium condition of these experiments with the equilibrium condition of a control simulation, forced by perpetual solar maximum conditions. In SCUV, we observe large stratospheric cooling due to ozone reduction. In both the Northern Hemisphere (NH) and the Southern Hemisphere (SH), this is accompanied by a weakening of the polar night jet during the cold season. In TOTC, dynamically induced polar stratospheric cooling is observed in the transition seasons over the NH, without any ozone deficit. The global temperature cooling values, compared with the control climate, are 0.55±0.03 K in TOTC and 0.39±0.03 K in SCUV. The reductions in total meridional heat transport outside of the subtropics are similar in the two experiments, especially in the SH. Despite substantial differences in stratospheric forcing, similarities exist between the two experiments, such as cloudiness; meridional heating transport in the SH; and strong cooling in the NH during wintertime, although this cooling affects two different regions, namely, North America in TOTC and the Euro–Asian continent in SCUV.

MDPI

2023

The role of SVOCs in the initial film formation and soiling of unvarnished paintings

Grøntoft, Terje; Cutajar, Jan Dariusz

In recent years increased research efforts and environmental improvements have been directed towards the preventive conservation of the monumental, unvarnished oil paintings on canvas (1909–1916) by Edvard Munch (1863–1944) housed in the University of Oslo Aula. Surface soiling of the paintings has been a documented issue since their display, and the modern-day effect of air-borne particulates and gases on the painting surfaces remains hitherto undocumented. For the first time in the Aula, this study has measured the in-situ time-dependent mass deposit of air pollution onto vertical surfaces over the period of one year (2021–2022). Concomitant measurements of the concentrations of ozone (O3) and nitrogen dioxide (NO2) were also taken, to complement periodic data from 2020. The mass deposit was measured through incremental weight changes of Teflon membrane filters, and quartz filters for analysis of elemental/organic carbon (EC/OC), whilst the gaseous pollutants were measured using passive gas samplers. Indoor-to-outdoor ratios (I/O) for O3 were noted to be higher than those suggested by earlier data, whereas NO2 I/O ratios were found to be lower, indicating a stronger oxidising atmosphere in the Aula. Just over half of the deposited mass on the quartz filters was found to be OC, with no EC detected. Surprisingly, an overall decrease in the mass deposit from three to twelve months was measured on the Teflon membrane filters. It was hypothesised, based on models reported in the literature, that the source of the OC on the filters was mainly gaseous, semi-volatile organic compounds (SVOCs), which were present in an adsorption/desorption equilibrium that was dependent on possible SVOC emission episodes, relative humidity levels, gaseous oxidative reactions and the particulate matter deposit. A simple mathematical model is proposed to rationalise the observed mass deposits on the filters, together with a discussion of uncertainties affecting the measurements. The hypothesis preliminarily indicates the possible and previously unconsidered role of SVOCs on the initial film formation of soiling layers on the Aula paintings, and could bear implications for their monitoring in the preventive care of unvarnished oil paintings on canvas.

Springer

2023

A top-down estimation of subnational CO2 budget using a global high-resolution inverse model with data from regional surface networks

Nayagam, Lorna Raja; Maksyutov, Shamil; Oda, Tomohiro; Janardanan, Rajesh; Trisolino, Pamela; Zeng, Jiye; Kaiser, Johannes; Matsunaga, Tsuneo

Top-down approaches, such as atmospheric inversions, are a promising tool for evaluating emission estimates based on activity-data. In particular, there is a need to examine carbon budgets at subnational scales (e.g. state/province), since this is where the climate mitigation policies occur. In this study, the subnational scale anthropogenic CO2 emissions are estimated using a high-resolution global CO2 inverse model. The approach is distinctive with the use of continuous atmospheric measurements from regional/urban networks along with background monitoring data for the period 2015–2019 in global inversion. The measurements from several urban areas of the U.S., Europe and Japan, together with recent high-resolution emission inventories and data-driven flux datasets were utilized to estimate the fossil emissions across the urban areas of the world. By jointly optimizing fossil fuel and natural fluxes, the model is able to contribute additional information to the evaluation of province–scale emissions, provided that sufficient regional network observations are available. The fossil CO2 emission estimates over the U.S. states such as Indiana, Massachusetts, Connecticut, New York, Virginia and Maryland were found to have a reasonable agreement with the Environmental Protection Agency (EPA) inventory, and the model corrects the emissions substantially towards the EPA estimates for California and Indiana. The emission estimates over the United Kingdom, France and Germany are comparable with the regional inventory TNO–CAMS. We evaluated model estimates using independent aircraft observations, while comparison with the CarbonTracker model fluxes confirms ability to represent the biospheric fluxes. This study highlights the potential of the newly developed inverse modeling system to utilize the atmospheric data collected from the regional networks and other observation platforms for further enhancing the ability to perform top-down carbon budget assessment at subnational scales and support the monitoring and mitigation of greenhouse gas emissions.

2023

The consolidated European synthesis of CO2 emissions and removals for the European Union and United Kingdom: 1990–2020

McGrath, Matthew J; Petrescu, Ana Maria Roxana; Peylin, Philippe; Andrew, Robbie; Matthews, Bradley; Dentener, Frank; Balkovič, Juraj; Bastrikov, Vladislav; Becker, Meike; Broquet, Gregoire; Ciais, Philippe; Fortems-Cheiney, Audrey; Ganzenmüller, Raphael; Grassi, Giacomo; Harrison, Ian; Jones, Carl Matthew; Knauer, Jürgen; Kuhnert, Matthias; Monteil, Guillaume; Munassar, Saqr; Palmer, Paul I.; Peters, Glen Philip; Qiu, Chunjing; Schelhaas, Mart-Jan; Tarasova, Oksana; Vizzarri, Matteo; Winkler, Karina; Balsamo, Gianpaolo; Berchet, Antoine; Briggs, Peter R; Brockmann, Patrick; Chevallier, Frédéric; Conchedda, Giulia; Monica, Crippa; Dellaert, Stijn N. C.; van der Gon, Hugo A.C. Denier; Filipek, Sara; Friedlingstein, Pierre; Fuchs, Richard; Gauss, Michael; Gerbig, Christoph; Guizzardi, Diego; Günther, Dirk; Houghton, Richard A; Janssens-Maenhout, Greet; Lauerwald, Ronny; Lerink, Bas; Luijkx, Ingrid T.; Moulas, Géraud; Muntean, Marilena; Nabuurs, Gert-Jan; Paquirissamy, Aurélie; Perugini, Lucia; Peters, Wouter; Pilli, Roberto; Pongratz, Julia; Regnier, Pierre; Scholze, Marko; Serengil, Yusuf; Smith, Peter; Solazzo, Efisio; Thompson, Rona Louise; Tubiello, Francesco N.; Vesala, Timo; Walther, Sophia

2023

Interpolation, Satellite-Based Machine Learning, or Meteorological Simulation? A Comparison Analysis for Spatio-temporal Mapping of Mesoscale Urban Air Temperature

Hassani, Amirhossein; Sousa Santos, Gabriela; Schneider, Philipp; Castell, Nuria

Fine-resolution spatio-temporal maps of near-surface urban air temperature (Ta) provide crucial data inputs for sustainable urban decision-making, personal heat exposure, and climate-relevant epidemiological studies. The recent availability of IoT weather station data allows for high-resolution urban Ta mapping using approaches such as interpolation techniques or machine learning (ML). This study is aimed at executing these approaches and traditional numerical modeling within a practical and operational framework and evaluate their practicality and efficiency in cases where data availability, computational constraints, or specialized expertise pose challenges. We employ Netatmo crowd-sourced weather station data and three geospatial mapping approaches: (1) Ordinary Kriging, (2) statistical ML model (using predictors primarily derived from Earth Observation Data), and (3) weather research and forecasting model (WRF) to predict/map daily Ta at nearly 1-km spatial resolution in Warsaw (Poland) for June–September and compare the predictions against observations from 5 meteorological reference stations. The results reveal that ML can serve as a viable alternative approach to traditional kriging and numerical simulation, characterized by reduced complexity and higher computational speeds within the domain of urban meteorological studies (overall RMSE = 1.06 °C and R2 = 0.94, compared to ground-based meteorological stations). The results have implications for identifying the urban regions vulnerable to overheating and evidence-based urban management in response to climate change. Due to the open-sourced nature of the applied predictors and input parsimony, the ML method can be easily replicated for other EU cities.

2023

Impacts of a warming climate on concentrations of organochlorines in a fasting high arctic marine bird: Direct vs. indirect effects?

Bustnes, Jan Ove; Bårdsen, Bård-Jørgen; Moe, Børge; Herzke, Dorte; Ballesteros, Manuel; Fenstad, Anette; Borgå, Katrine; Krogseth, Ingjerd Sunde; Eulaers, Igor; Skogeng, Lovise Pedersen; Gabrielsen, Geir Wing; Hanssen, Sveinn Are

The present study examined how climate changes may impact the concentrations of lipophilic organochlorines (OCs) in the blood of fasting High Arctic common eiders (Somateria mollissima) during incubation. Polychlorinated biphenyls (PCBs), 1-dichloro-2,2-bis (p-chlorophenyl) ethylene (p,p′-DDE), hexachlorobenzene (HCB) and four chlordane compounds (oxychlordane, trans-chlordane and trans- and cis-nonachlor) were measured in females at chick hatching (n = 223) over 11 years (2007–2017). Firstly, median HCB and p,p′-DDE concentrations increased ~75 % over the study period, whereas median chlordane concentrations doubled (except for oxychlordane). PCB concentrations, in contrast, remained stable over the study period. Secondly, both body mass and clutch size were negatively associated with OC levels, suggesting that females with high lipid metabolism redistributed more OCs from adipose tissue, and that egg production is an important elimination route for OCs. Thirdly, the direct climate effects were assessed using the mean effective temperature (ET: air temperature and wind speed) during incubation, and we hypothesized that a low ET would increase redistribution of OCs. Contrary to expectation, the ET was positively correlated to most OCs, suggesting that a warmer climate may lead to higher OCs levels, and that the impact of ET may not be direct. Finally, potential indirect impacts were examined using the Arctic Oscillation (AO) in the three preceding winters (AOwinter 1–3) as a proxy for potential long-range transport of OCs, and for local spring climate conditions. In addition, we used chlorophyll a (Chla) as a measure of spring primary production. There were negative associations between AOwinter 1 and HCB, trans-chlordane and trans-nonachlor, whereas oxychlordane and cis-chlordane were negatively associated with Chla. This suggests that potential indirect climate effects on eiders were manifested through the food chain and not through increased long-range transport, although these relationships were relatively weak.

Elsevier

2023

Method for retrieval of aerosol optical depth from multichannel irradiance measurements

Sztipanov, Milos; Li, Wei; Dahlback, Arne; Stamnes, Jakob J.; Svendby, Tove Marit; Stamnes, Knut

We present, to the best of our knowledge, a new method for retrieval of aerosol optical depth from multichannel irradiance measurements. A radiative transfer model is used to simulate measurements to create the new aerosol optical depth retrieval method. A description of the algorithm, simulations, proof of principle, merits, possible future developments and implementations is provided. As a demonstration, measurements in the New York City area are simulated based on the specific channel configuration of an existing multichannel irradiance instrument. Verification of the method with irradiance measurement data is also provided.

Optical Society of America

2023

Arctic Tropospheric Ozone Trends

Law, Kathy S.; Hjorth, Jens Liengaard; Pernov, Jakob B.; Whaley, Cynthia; Skov, Henrik; Coen, Martine Collaud; Langner, Joakim; Arnold, Stephen R.; Tarasick, David; Christensen, Jesper; Deushi, Makoto; Effertz, Peter; Faluvegi, Greg; Gauss, Michael; Im, Ulas; Oshima, Naga; Petropavlovskikh, Irina; Plummer, David; Tsigaridis, Kostas; Tsyro, Svetlana; Solberg, Sverre; Turnock, Stephen

Observed trends in tropospheric ozone, an important air pollutant and short-lived climate forcer (SLCF), are estimated using available surface and ozonesonde profile data for 1993–2019, using a coherent methodology, and compared to modeled trends (1995–2015) from the Arctic Monitoring Assessment Program SLCF 2021 assessment. Increases in observed surface ozone at Arctic coastal sites, notably during winter, and concurrent decreasing trends in surface carbon monoxide, are generally captured by multi-model median trends. Wintertime increases are also estimated in the free troposphere at most Arctic sites, with decreases during spring months. Winter trends tend to be overestimated by the multi-model medians. Springtime surface ozone increases in northern coastal Alaska are not simulated while negative springtime trends in northern Scandinavia are not always reproduced. Possible reasons for observed changes and model performance are discussed including decreasing precursor emissions, changing ozone dry deposition, and variability in large-scale meteorology.

American Geophysical Union (AGU)

2023

The atmospheric fate of 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH): spatial patterns, seasonal variability, and deposition to Canadian coastal regions

Oh, Jenny; Shunthirasingham, Chubashini; Lei, Ying Duan; Zhan, Faqiang; Li, Yuening; Dalpé Castilloux, Abigaëlle; Ben Chaaben, Amina; Lu, Zhe; Lee, Kelsey; Gobas, Frank A. P. C.; Eckhardt, Sabine; Alexandrou, Nick; Hung, Hayley; Wania, Frank

Brominated flame retardants (BFRs) that are gradually being phased out are being replaced by emerging BFRs. Here, we report the concentration of the α- and β-isomers of 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH; also known as DBE-DBCH) in over 300 air, water, and precipitation samples collected between 2019 and 2022 using active air and deposition sampling as well as networks of passive air and water samplers. The sampling region includes Canada's most populated cities and areas along the St. Lawrence River and Estuary, Quebec, as well as around the Salish Sea, British Columbia. TBECH was detected in over 60 % of air samples at levels comparable to those of 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47). Concentrations of TBECH and BDE-47 were typically higher in urban areas, with stronger correlations with population density during warmer deployments. Uniform α-  β-TBECH ratios across space, time, and environmental media indicate the highly similar atmospheric fate of the two isomers. Although TBECH air concentrations were strongly related to temperature in urban Toronto and a remote site on the east coast, the lack of such dependence at a remote site on the west coast can be explained by the small seasonal temperature range and summertime air mass transport from the Pacific Ocean. Despite there being no evidence that TBECH has been produced, or imported for use, in Canada, it is now one of the most abundant gaseous BFRs in the Canadian atmosphere. The recorded spatial and temporal variability of TBECH suggest that its emissions are not constrained to specific locations but are generally tied to the presence of humans. The most likely explanation for its environmental occurrence in Canada is the release from imported consumer products containing TBECH. Chiral analysis suggests that despite its urban origin, at least some fraction of TBECH has experienced enantioselective processing, i.e., has volatilized from reservoirs where it has undergone microbial transformations. Microbial processes in urban soils and in marine waters may have divergent enantioselectivity.

2023

Image-Text Connection: Exploring the Expansion of the Diversity Within Joint Feature Space Similarity Score

Mohammadi, Mahsa; Eftekhari, Mahdi; Hassani, Amirhossein

Cross-modal representation learning aims to learn a shared representation space where data from multiple modalities can be effectively compared, fused, and understood. This paper investigates the role of increased diversity in the similarity score matrix in enhancing the performance of the CLIP (Contrastive Language-Image Pretraining), a multi-modal learning model that establishes a connection between images and text within a joint embedding space. Two transforming approaches, sine and sigmoid (including two versions), are incorporated into the CLIP model to amplify larger values and diminish smaller values within the similarity matrix (logits). Hardware limitations are addressed using a more compact text encoder (DistilBERT) and a pre-trained ResNet50 image encoder. The proposed adaptations are evaluated on various benchmarks, including image classification and image/text retrieval tasks, using 10 benchmark datasets such as Food101, Flickr30k, and COCO. The performance of the adapted models is compared to the base CLIP model using Accuracy, mean per class, and Recall@k metrics. The results demonstrate improvements in Accuracy (up to 5.32% enhancement for the PatchCamelyon dataset), mean per class (up to 14.48% enhancement for the FGVCAircraft dataset), and retrieval precision (with an increase of up to 45.20% in Recall@1 for the COCO dataset), compared to the baseline algorithm (CLIP).

IEEE (Institute of Electrical and Electronics Engineers)

2023

Circular economy for aquatic food systems: insights from a multiscale phosphorus flow analysis in Norway

Pandit, Avijit Vinayak; Dittrich, Nils Maximilian; Strand, Andrea Viken; Lozach, Loïs; Las Heras Hernandez, Miguel; Reitan, Kjell Inge; Mueller, Daniel Beat

As wild-caught fish become scarce, feed ingredients for farming fish, such as salmon, are increasingly sourced from agricultural plants that depend on mineral fertilizers. Since these fish are naturally carnivorous, they have difficulty digesting the phosphorus in plant-based feed. So additional phosphorus supplements are added to the feed, resulting in a disproportionate increase in mineral phosphorus use and emission. Aquatic food production is increasingly relying on agriculture and mineral phosphorus resources. The feed surplus and the excreta are seldom collected and recycled, leading to a massive loss of nutrients to water bodies and the seafloor, resulting in local risk for eutrophication. Norway currently produces more than half of the world’s Atlantic salmon, and it is set to increase production from currently 1.5 to 5 Mt. in 2050. This has large implications for feed supply and emissions globally. There is a lack of studies that analyze the phosphorus system in aquatic food production at a sufficient spatial and temporal granularity to effectively inform interventions for a more circular use of phosphorus. Here, we present a multi-scale phosphorus flow analysis at monthly resolution ranging between 2005 and 2021 for aquatic food production in Norway and quantitatively discuss the effectiveness of alternative strategies for improving resource efficiency. The results indicate that P emissions from aquaculture have nearly doubled in the period between 2005 and 2021. The P use efficiency (PUE) in Norwegian aquaculture was 19% in 2021. The addition of phytase to the feed could improve the PUE by 8% by reducing P supplements and emissions by 7 kt/y. The use of Integrated Multi-Trophic Aquaculture close to fish farming sites could absorb emissions by 4 kt/y by creating new marine food products. Sludge collection systems could reduce P emissions by 4 to 11 kt/y, depending on the technology. Using the sludge in local agriculture would exacerbate the current P accumulation in soils close to the coastline, given that the animal density in this region is already high. Hence, a large and sophisticated processing infrastructure will be needed to create transportable, high-quality secondary fertilizers for effective sludge recycling in regions with a P deficit.

Frontiers Media S.A.

2023

Review of Interpreting Gaseous Pollution Data Regarding Heritage Objects

Thickett, David; Grøntoft, Terje

Pollutant gases pose a significant risk to some cultural heritage objects, and surveys have shown that the professionals involved consider themselves to lack knowledge to fully assess risk. Three approaches towards risk assessment, research results, standards and damage functions have been considered. An assessment tool has been developed, collating over 4000 research reports into a scheme for the impact on 22 materials of acetic and formic acids, nitrogen dioxide, ozone and reduced sulphur gases. The application of doses or concentrations has been considered, the impact of measurement time compared to annual exposure investigated and a simple tool derived.

MDPI

2023

A rise in HFC-23 emissions from eastern Asia since 2015

Park, Hyeri; Kim, Jooil; Choi, Haklim; Geum, Sohyeon; Kim, Yeaseul; Thompson, Rona Louise; Mühle, Jens; Salameh, Peter K.; Harth, Christina M.; Stanley, Kieran M.; O'Doherty, Simon; Fraser, Paul J.; Simmonds, Peter G.; Krummel, Paul B.; Weiss, Ray F.; Prinn, Ronald G.; Park, Sunyoung

Trifluoromethane (CHF3, HFC-23), one of the most potent greenhouse gases among hydrofluorocarbons (HFCs), is mainly emitted to the atmosphere as a by-product in the production of the ozone-depleting legacy refrigerant and chemical feedstock chlorodifluoromethane (CHClF2, HCFC-22). A recent study on atmospheric observation-based global HFC-23 emissions (top-down estimates) showed significant discrepancies over 2014–2017 between the increase in the observation-derived emissions and the 87 % emission reduction expected from capture and destruction processes of HFC-23 at HCFC-22 production facilities implemented by national phase-out plans (bottom-up emission estimates) (Stanley et al., 2020). However, the actual regions responsible for the increased emissions were not identified. Here, we estimate the regional top-down emissions of HFC-23 for eastern Asia based on in situ measurements at Gosan, South Korea, and show that the HFC-23 emissions from eastern China have increased from 5.0±0.4 Gg yr−1 in 2008 to 9.5±1.0 Gg yr−1 in 2019. The continuous rise since 2015 was contrary to the large emissions reduction reported under the Chinese hydrochlorofluorocarbons production phase-out management plan (HPPMP). The cumulative difference between top-down and bottom-up estimates for 2015–2019 in eastern China was  Gg, which accounts for 47±11 % of the global mismatch. Our analysis based on HCFC-22 production information suggests the HFC-23 emissions rise in eastern China is more likely associated with known HCFC-22 production facilities rather than the existence of unreported, unknown HCFC-22 production, and thus observed discrepancies between top-down and bottom-up emissions could be attributed to unsuccessful factory-level HFC-23 abatement and inaccurate quantification of emission reductions.

2023

Evaluation of meso- and microplastic ingestion by the northern fulmar through a non-lethal sampling method

Collard, France; Strøm, Hallvard; Fayet, Marie-Océane; Gudmundsson, Fannar Theyr; Herzke, Dorte; Hotvedt, Ådne; Løchen, Arja; Malherbe, Cédric; Eppe, Gauthier; Gabrielsen, Geir W.

An increasing number of organisms from the polar regions are reported contaminated by plastic. Rarely a non-killing sampling method is used. In this study we wanted to assess plastic levels using stomach flushing and evaluate the method suitability for further research and monitoring. The stomach of 22 fulmars from Bjørnøya, Svalbard, were flushed with water in the field. On return to the laboratory, the regurgitated content was digested using potassium hydroxide. The extracted plastics were visually characterised and analysed with spectroscopy. Only three birds had plastics in their stomach, totaling 36 particles, most of them microplastics (< 5 mm). The plastic burdens are much lower than previously reported in Svalbard. The stomach flushing is assumed not to allow the collection of the gizzard content. This is a major limitation as most of the plastics accumulate in the fulmar's gizzard. However, the method is still useful for studies investigating plastic ingestion dynamics, allowing to sample the same individuals over time.

Elsevier

2023

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