Methane emissions inventory verification in southern California

Methane (CH4) and carbon monoxide (CO) mixing ratios were measured at an air quality monitoring station near the Mt. Wilson (MW) Observatory in southern California starting in the spring of 2007. Diurnal variation and mixing ratio correlation (R2 = 0.81) were observed. The correlation results observed agree with previous aircraft measurements collected over the greater Los Angeles (LA) metropolitan area. The consistent agreement between CH4 and CO indicates these gases are well-mixed before reaching the sampling site and the emission source contributions of both compounds are reasonably constant. Since CH4 and CO are considered non-reactive on the time scale of dispersion within the LA urban area and their emission sources are likely to be similarly distributed (e.g., associated with human activities) they are subject to similar scales of atmospheric transport and dilution. This behavior allows the relationship of CH4 and CO to be applied for estimation of CH4 emissions using well-documented CO emissions. Applying this relationship a "top-down" CH4 inventory was calculated for LA County based on the measurements observed at MW and compared with the California Air Resources Board (CARB) "bottom-up" CH4 emissions inventory based on the Intergovernmental Panel on Climate Change recommended methodologies. The "top-down" CH4 emissions inventory is approximately one-third greater than CARB's "bottom-up" inventory for LA County. Considering the uncertainties in both methodologies, the different CH4 emissions inventory approaches are in good agreement, although some under and/or uninventoried CH4 sources may exist

Emission estimates of HCFCs and HFCs in California from the 2010 CalNex study

The CalNex 2010 (California Research at the Nexus of Air Quality and Climate Change) study was designed to evaluate the chemical composition of air masses over key source regions in California. During May to June 2010, air samples were collected on board a National Oceanic and Atmospheric Administration (NOAA) WP-3D aircraft over the South Coast Air Basin of California (SoCAB) and the Central Valley (CV). This paper analyzes six effective greenhouse gases - chlorodifluoromethane (HCFC-22), 1,1-dichloro-1-fluoroethane (HCFC-141b), 1-chloro-1,1-difluoroethane (HCFC-142b), 2-chloro-1,1,1,2-tetrafluoroethane (HCFC-124), 1,1,1,2- tetrafluoroethane (HFC-134a), and 1,1-difluoroethane (HFC-152a) - providing the most comprehensive characterization of chlorofluorocarbon (CFC) replacement compound emissions in California. Concentrations of measured HCFCs and HFCs are enhanced greatly throughout the SoCAB and CV, with highest levels observed in the SoCAB: 310 ± 92 pptv for HCFC-22, 30.7 ± 18.6 pptv for HCFC-141b, 22.9 ± 2.0 pptv for HCFC-142b, 4.86 ± 2.56 pptv for HCFC-124, 109 ± 46.4 pptv for HFC-134a, and 91.2 ± 63.9 pptv for HFC-152a. Annual emission rates are estimated for all six compounds in the SoCAB using the measured halocarbon to carbon monoxide (CO) mixing ratios and CO emissions inventories. Emission rates of 3.05 ± 0.70 Gg for HCFC-22, 0.27 ± 0.07 Gg for HCFC-141b, 0.06 ± 0.01 Gg for HCFC-142b, 0.11 ± 0.03 Gg for HCFC-124, 1.89 ± 0.43 Gg for HFC-134a, and 1.94 ± 0.45 Gg for HFC-152b for the year 2010 are calculated for the SoCAB. These emissions are extrapolated from the SoCAB region to the state of California using population data. Results from this study provide a baseline emission rate that will help future studies determine if HCFC and HFC mitigation strategies are successful. Key PointsHCFC and HFC emissions are calculated for the year 2010 for the SoCABEmissions are extrapolated to the state of CaliforniaEmissions are calculated using CalNex field measurements © 2013. American Geophysical Union. All Rights Reserved

Modeling the Non-Industrial Gut Microbiota: Effect of Diet on Structure and Function

The gut microbiota of non-industrial populations is known to be more diverse than the gut microbiota of industrial populations. The ‘missing’ microbes hypothesis would implicate microbes lost in industrial populations in the rise of non-communicable diseases that non-industrial populations appear to be protected against. This thesis aims to expand what is currently known of non-industrial gut microbiota by studying the Yanomami, a semi-nomadic hunter-gatherer population of the Amazon rainforest. Marker gene sequencing was conducted on Yanomami fecal samples (n = 9) and expeditioner fecal samples (n = 2) to determine the microbial community structure of this remote population, and whether non-industrial microbes were present in a Western expeditioner on their travels. Culture-based approaches and in vitro modelling with a chemostat system were conducted on two Yanomami samples and one expeditioner sample to obtain a reference library of non-industrial gut microbiota and determine whether non-industrial gut microbiota could be sustained in vitro. It was determined that the Yanomami samples had higher richness than the expeditioner, and a total of 929 strains representing 296 species across 8 phyla were isolated from Yanomami and expeditioner samples. One of the first cultivated Treponema spp. from the human gut was obtained from the Yanomami samples. By adapting the distal gut chemostat model to account for differences in diet in industrial and non-industrial populations, it was found that the adapted system could sustain microbial diversity and functionality. The results from this thesis complement previous findings from other non-industrial gut microbiota and are the first to demonstrate in vitro modelling of the non-industrial gut microbial community that can next be used to study the impact of various stimuli, including consequences of industrialization factors on the non-industrial gut microbiota without the use of human subjects

A super Asian dust storm over the East and South China Seas: disproportionate dust deposition

A super Asian dust (SAD) storm that originated from North China has affected East Asia since 20 March 2010. The tempo-spatial and size distributions of aerosol Al, a tracer of wind-blown dust, were measured on a regional aerosol network in March 2010. Two dust events were recorded: the SAD and a relatively moderate AD event. The SAD clouds raised Al concentrations to ~50 µg/m3 on 21 and 22 March over the East China Sea (ECS) and occupied there for ~5 days. The SAD plume also stretched toward the South China Sea (SCS) on 21 March however, it caused a maximum Al concentration of ~8.5 µg/m3 only, much lower than that observed in the ECS. In comparison, a weaker dust plume on 16 March caused Al maximum of ~4 µg/m3 over the ECS, and comparably, ~3 µg/m3 in the SCS. Dry dust deposition was measured during the peak phase of the SAD at 178 mg/m2/d, which corresponded to dry deposition velocities of 0.2–0.6 cm/s only, much lower than the commonly adopted one (1–2 cm/s). The corresponding increase in dust deposition by the SAD was up to a factor of ~12, which was, however, considerably disproportionate to the increase in dust concentration (i.e., the factor of over 100). In certain cases, synoptic atmospheric conditions appear to be more important in regulating dust contribution to the SCS than the strength of AD storms

Improving Completion Rates for Underrepresented Populations

Most experienced educators recognize that many students will not complete optional assignments, and often those students who need additional help do not seek assistance. Current research demonstrates that students in underrepresented populations (see definition below) are less likely to seek support than others because they see needing help as a confirmation that they don’t really “belong” in college in the first place. Research shows that those who do access currently optional supports such as tutoring are more likely to succeed, so this research group looked for ways to build structured connections between underrepresented students and resources. We found that our peers at various VCCS colleges had programs that were working to build these connections for our students, so in our resource-constrained environment, we chose to focus on what exists that works, is scalable, and could be implemented in stages as resources permit. Our proposal reflects increased resource allocation on both the academic support (tutoring) side and the student support (TRIO, Pathway to the Baccalaureate, Success Coaches) side to increase structured contact between the student and the support to decrease the “stigma” of seeking help. We propose this because in our roles as administrators and faculty we know that often our students need both academic support and holistic support

Influence of free and immobilized chitosan on a defined human gut microbial ecosystem

[EN] In this work, the influence of different forms of presentation of chitosan in the human gut microbiota with a defined bacterial community was evaluated. First, the susceptibility of individual gut bacterial isolates against chitosan was studied within a concentration range between 0.125 and 1 mg/mL. Then, the impact of chitosan (0.25 and 1 mg/mL) on a defined human gut microbial ecosystem was studied by metagenomic and metabonomic analyses. The results showed that chitosan in its free form had a high impact on individual isolates with a minimum inhibitory concentration below 1 mg/mL for most of the strains studied. In comparison, chitosan immobilized in the different carriers displayed a diverse effect on gut microbiota. The most susceptible strains were Agathobacter rectalis strain 16-6-I 1 FAA, Clostridium spiroforme strain 16-6-I 21 FAA and Mediterraneibacter faecis strain 16-6-I 30 FAA. The impact of the different modes of presentation of chitosan was strain-specific and species-specific when compared to results obtained from analysis of other strains within the genera Agathobacter, Clostridium and Mediterraneibacter, and therefore a study using a defined ecosystem was needed to extrapolate the results. Significant decreases in defined community richness and diversity and changes in metabolic profile were observed after exposure to free chitosan. Free chitosan produced significant reductions in the abundance of the genera Lachnoclostridium, Anaerotignum, Blautia, Enterococcus, Eubacterium and Ruthenibacterium together with a slight decrease of the production of SCFAs, among other fermentation by-products. The immobilized chitosan significantly alleviated the impact caused by the antimicrobial polymer and significantly increased the relative abundance of the Bacteroidetes phylum compared to free chitosan. These results suggest the significance of assessing the impact of new ingredients and materials included in food on the human gut microbiota with models that simulate the gastrointestinal environment, such as in vitro bioreactor systems.The authors gratefully acknowledge the financial support from the grant RTI2018-101599-B-C21 of the project "Retos Investigacion" funded by MCIN/AEI/10.13039/501100011033 and by "ERDF A way of making Europe". MRR acknowledges the Generalitat Valenciana for her postdoctoral fellowship (APOSTD/2019/118).Ruiz Rico, M.; Rendwick, S.; Vancuren, SJ.; Robinson, AV.; Gianetto-Hill, C.; Allen-Vercoe, E.; Barat Baviera, JM. (2022). Influence of free and immobilized chitosan on a defined human gut microbial ecosystem. Food Research International. 161:1-11. https://doi.org/10.1016/j.foodres.2022.11189011116

Impact of food preservatives based on immobilized phenolic compounds on an in vitro model of human gut microbiota

[EN] To address concerns about the biocompatibility of novel phenolic immobilization-based food preservatives, their impact on the composition and metabonomic profile of a defined community of human gut microbiota was evaluated. Three phenolics (eugenol, vanillin and ferulic acid) presented in two forms (free or immobilized on different supports) were tested at two concentration levels (0.5 and 2 mg/mL). Free eugenol was the phenolic with the greatest impact on gut microbiota, with a remarkable increase in the abundance of Lachnospiraceae and Akkermansiaceae families. In contrast, immobilized phenolics produced an increase in the abundance of Bac-teroides with a reduction in the ratio of Firmicutes to Bacteroidetes. The metabonomic profile was also affected by free and immobilized phenolics differently in terms of fermentation by-products and phenolic biotransformation metabolites. Thus the results suggest the importance of evaluating the impact of new compounds or materials added to food on human gut microbiota and their potential use to modulate microbiota composition.The authors gratefully acknowledge the financial support from the grant RTI2018-101599-B-C21 of the project "Retos Investigacion" funded by MCIN/AEI/10.13039/501100011033 and by "ERDF A way of making Europe". M.R.R. acknowledges the Generalitat Valenciana for her postdoctoral fellowship (APOSTD/2019/118)Ruiz Rico, M.; Renwick, S.; Vancuren, SJ.; Robinson, AV.; Gianetto-Hill, C.; Allen-Vercoe, E.; Barat Baviera, JM. (2023). Impact of food preservatives based on immobilized phenolic compounds on an in vitro model of human gut microbiota. Food Chemistry. 403. https://doi.org/10.1016/j.foodchem.2022.13436340

Wintertime phytoplankton bloom in the subarctic Pacific supported by continental margin iron

Author Posting. © American Geophysical Union, 2006. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Global Biogeochemical Cycles 20 (2006): GB1006, doi:10.1029/2005GB002557.Heightened biological activity was observed in February 1996 in the high-nutrient low-chlorophyll (HNLC) subarctic North Pacific Ocean, a region that is thought to be iron-limited. Here we provide evidence supporting the hypothesis that Ocean Station Papa (OSP) in the subarctic Pacific received a lateral supply of particulate iron from the continental margin off the Aleutian Islands in the winter, coincident with the observed biological bloom. Synchrotron X-ray analysis was used to describe the physical form, chemistry, and depth distributions of iron in size fractionated particulate matter samples. The analysis reveals that discrete micron-sized iron-rich hot spots are ubiquitous in the upper 200 m at OSP, more than 900 km from the closest coast. The specifics of the chemistry and depth profiles of the Fe hot spots trace them to the continental margins. We thus hypothesize that iron hot spots are a marker for the delivery of iron from the continental margin. We confirm the delivery of continental margin iron to the open ocean using an ocean general circulation model with an iron-like tracer source at the continental margin. We suggest that iron from the continental margin stimulated a wintertime phytoplankton bloom, partially relieving the HNLC condition.This work was supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research (KP1202030) to J. K. B and by NSFATM-9987457 to I. F. The Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences, Division of Materials Sciences and Division of Chemical Sciences, Geosciences, and Biosciences of the U.S. Department of Energy at Lawrence Berkeley National Laboratory under contract DE-AC03-76SF00098

Pb Isotopes as an Indicator of the Asian Contribution to Particulate Air Pollution in Urban California

During the last two decades, expanding industrial activity in east Asia has led to increased production of airborne pollutants that can be transported to North America. Previous efforts to detect this trans-Pacific pollution have relied upon remote sensing and remote sample locations. We tested whether Pb isotope ratios in airborne particles can be used to directly evaluate the Asian contribution to airborne particles of anthropogenic origin in western North America, using a time series of samples from a pair of sites upwind and downwind of the San Francisco Bay Area. Our results for airborne Pb at these sites indicate a median value of 29 Asian origin, based on mixing relations between distinct regional sample groups. This trans-Pacific Pb is present in small quantities but serves as a tracer for airborne particles within the growing Asian industrial plume. We then applied this analysis to archived samples from urban sites in central California. Taken together, our results suggest that the analysis of Pb isotopes can reveal the distribution of airborne particles affected by Asian industrial pollution at urban sites in northern California. Under suitable circumstances, this analysis can improve understanding of the global transport of pollution, independent of transport models