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In the face of mounting global climatic pressures, negative emission technologies (NETs) for carbon dioxide removal (CDR) are increasingly proposed as necessary for meeting climate targets. While initial work has identified the potential of terrestrial NETs, a diverse set of marine/ocean-based NETs are gaining new and particular attention. Emerging studies on the feasibility of marine NETs are urgently needed, especially to explore the logics that public groups use to judge different approaches, and to ensure that design and governance of these technologies align with public values and priorities. This study explores factors of interest in understanding public views on four marine NETs, both perceptions of climate severity and urgency, and beliefs about marine environments. It uses a quantitative survey to explore how a representative sample of people in British Columbia, Canada and Washington state, United States evaluate four marine NETs: coastal restoration; ocean alkalinity enhancement; ocean fertilization; and offshore direct air carbon capture and storage. We find that perceived severity and urgency of climate change predicts greater comfort with all NETs studied, and views of marine environments as adaptable, fragile and manageable vary in predicting both greater and lesser comfort. Drawing upon these insights, the paper offers reflections on the conditional thinking linked with emerging views of marine NETs, concluding with methodological suggestions for future research on public perceptions as concerns the deployment of ocean-based CDR near and long term. Incorporating these insights into policy for ocean-based CDR will be important to ensuring responsible governance of these technologies. Key policy insights Incorporating research on public perceptions will be important to the design of marine NETs and accompanying policies. Public groups in both British Columbia and Washington expressed high levels of comfort with coastal restoration, some comfort with offshore direct air carbon capture and storage, and some discomfort with ocean alkalinity enhancement and ocean fertilization. Perceived severity and urgency of climate change predicted greater comfort with all approaches; this evidence aligns with a small but growing body of scholarship indicating openness to environmental intervention amongst public groups concerned with climate impacts. Beliefs about marine environments, namely whether they are 'adaptable', 'manageable' or 'fragile', also predicted comfort, suggesting that CDR in ocean contexts requires further examination regarding public perceptions. [ABSTRACT FROM AUTHOR]

In spring 2002, an atmospheric measurement site was established at the peak of Whistler Mountain in British Columbia, Canada to measure trace gases, particle chemistry and physics, and meteorology. This paper uses continuous measurements from March 2002 to December 2006 to investigate the influence of trans-Pacific transport and North American forest fires on both O3 and CO at Whistler. Annual mean mixing ratios of O3 and CO were 41 ppbv (monthly means of 35-48 ppbv) and 145 ppbv (monthly means of 113-177 ppbv) respectively with both species exhibiting an annual cycle of late-winter to early-spring maxima and summer minima. The absence of a broad summer O3 peak differs from previously-reported high altitude sites in the western US. The highest monthly-averaged O3 and CO mixing ratios relative to the 5-yr monthly means were seen in fall 2002 and spring 2003 with increased O3 and CO of 10% and 25% respectively. These increases correspond to anomalously-high values reported at other Northern Hemisphere sites and are attributed to fires in the Russian Federation. Air mass back trajectory analysis is used to associate the mean enhancements of O3 and CO with trans-Pacific transported or North American air masses relative to the Pacific background. Mean values of the enhancements for March to June in trans-Pacific air masses were 6 ppbv and 16 ppbv for O3 and CO respectively. In summers 2002-2006, higher CO and O3 mixing ratios were almost always observed in North American air masses and this relative enhancement co-varied for each year with the western US and Canada total wild- fire area. The greatest enhancements in O3 and CO were seen in 2004, a record year for forest fires in Alaska and the Yukon Territory with average O3 and CO mixing ratios 13 and 43 ppbv above background values. [ABSTRACT FROM AUTHOR]

Area burned, number of fires, seasonal fire severity, and fire season length are all expected to increase in Canada, with largely unquantified ecosystem feedbacks. However, there are few observational studies measuring ecosystem-scale biogeochemical (e.g., carbon dioxide exchanges) and biophysical (e.g., energy partitioning) properties during smoke episodes and hence assessing responses of gross primary production (GPP) to changes in incoming diffuse photosynthetically active radiation (PAR). In this study, we leveraged two long-term eddy covariance measurement sites in forest and wetland ecosystems to study four smoke episodes, which happened at different times and differed in length, over 4 different years (2015, 2017, 2018, and 2020). We found that the highest decrease in shortwave irradiance due to smoke was about 50 % in July and August but increased to about 90 % when the smoke arrived in September. When the smoke arrived in the later stage of summer, impacts on sensible and latent heat fluxes were very different than the earlier ones. Smoke generally increased the diffuse fraction (DF) from ∼ 0.30 to ∼ 0.50 and turned both sites into stronger carbon dioxide (CO2) sinks with increased GPP up to ∼ 18 % and ∼ 7 % at the forest and wetland site, respectively. However, when DF exceeded 0.80 as a result of dense smoke, both ecosystems became net CO2 sources as total PAR dropped to low values. The results suggest that this kind of natural experiment is important for validating future predictions of smoke–productivity feedbacks. [ABSTRACT FROM AUTHOR]

Increasing concentrations of atmospheric greenhouse gases (GHGs; CO2, CH4, N2O) cause climate change. Depending on the conditions, soils have the potential to store carbon or to be a source of GHGs to the atmosphere. Riparian soils in particular have high potential to store carbon, but also to be sources of CH4 and N2O. Headwater streams make up a large proportion of stream length in a drainage network, and their riparian zones have valuable ecosystem functions. In parallel, the riparian zones of headwater streams are particularly vulnerable to forest harvest. Studies of GHG fluxes from these unique ecosystems remain limited. Our objective was to quantify the effects of forestry practices and groundwater discharge (DIS) areas on GHG emissions from riparian forest soils in coastal British Columbia. We compared nine sites with three different forest management protocols: (1) harvesting with a riparian buffer, (2) no buffer, and (3) reference sites without harvesting. We measured gas fluxes, soil temperature, soil moisture and depth to the groundwater table alongside headwater streams monthly over one growing season. We found that CH4 uptake rates were 65% lower at the no buffer sites, and N2O emission rates were 52% lower at the no buffer sites, when compared to the reference sites. Additionally, CH4 uptake was 54% lower at DIS areas than in non-DIS areas. The results of our research help inform forest management by demonstrating that maintaining riparian buffers can be effective in protecting the ecosystem functions contributing to soil GHG fluxes. [ABSTRACT FROM AUTHOR]

During the summer 2017 ASCENDS/ABoVE airborne science campaign, the NASA Goddard CO2 Sounder lidar overflew smoke plumes from wildfires in the British Columbia, Canada. In the flight path over Vancouver Island on 8 August 2017, the column XCO2 retrievals from the lidar measurements at flight altitudes around 9 km showed an average enhancement of 4 ppm from the wildfires. A comparison of these enhancements with those from the Goddard Global Chemistry Transport model suggested that the modeled CO2 emissions from wildfires were underestimated by more than a factor of 2. A spiral‐down validation performed at Moses Lake airport, Washington showed a bias of 0.1 ppm relative to in situ measurements and a standard deviation of 1 ppm in lidar XCO2 retrievals. The results show that future airborne campaigns and spaceborne missions with this type of lidar can improve estimates of CO2 emissions from wildfires and estimates of carbon fluxes globally. Plain Language Summary: Wildfires are a major source of greenhouse gases. However, there are large uncertainties in the estimated CO2 emissions from wildfires in global emissions inventories. The estimates of column‐averaged CO2 (XCO2) from satellite measurements using passive remote sensing techniques are significantly degraded or screened out by the scattering from smoke in the scene. NASA Goddard Space Flight Center has developed an integrated‐path, differential absorption lidar approach to measure XCO2 from space. Measurements of time‐resolved laser backscatter profiles from the atmosphere allow this technique to accurately estimate XCO2 and range to terrain and water surfaces even in the presence of wildfire smoke. We demonstrate this capability over Vancouver Island through the dense smoke plumes from wildfires in the Canadian Rockies during the summer 2017 ASCENDS/ABoVE airborne science campaign. To our knowledge this is the first use of lidar to remotely sense CO2 enhancements from large wildfires. Future airborne campaigns and spaceborne missions with this capability can improve estimates of CO2 emissions from wildfires and help estimates of carbon fluxes globally. Key Points: NASA Goddard CO2 Sounder Lidar can accurately measure CO2 enhancements from wildfires through dense smoke plumesThis is the first use of lidar to remotely sense CO2 enhancements from large wildfiresThese types of lidar measurements can be used to validate estimates of CO2 emissions from wildfires and improve estimates of carbon fluxes [ABSTRACT FROM AUTHOR]

• Two new advanced configurations for CO 2 capture in pulp mill was investigated. • A rate-based model in ProMax® 4.0 was used for modeling the CO 2 capture process. • Techno-economic assessment was analyzed for the new advanced configurations. • The combined effect of carbon tax and CO 2 sales price on the NBSK price was analyzed. • CO 2 capture plant in pulp mill only led to a slight increase in the NBSK pulp price. This project study involves the techno-economic assessment of two new advanced configurations for amine-based carbon dioxide capture from a pulp mill. The newly proposed advanced configurations include advanced rich amine four split (ARA4S), and advanced rich amine three split with desorber inter-heating (ARA3S-DI) which is aimed at reducing carbon capture cost and carbon emissions. The rate-based model in ProMax® 4.0 was used for the simulation study while the flue gas was provided by a 365,000 air dry tonne of pulp (ADt Pulp) per annum pulp mill in British Columbia, Canada. Comparative analysis revealed that the Capture Cost (US$/tCO 2 and US$/ADt Pulp) of the 5 kmol/m3 MEA system was lowest for the conventional configuration, while for the 2 kmol/m3 AMP-3 kmol/m3 MEA blend it was lowest for the advanced rich amine 3-split with desorber inter-heating configuration. In addition, the Capture Costs of the MEA solution with a conventional configuration system is 8.7% higher than the AMP-MEA blend with advanced rich amine three split with desorber inter-heating configuration. Sensitivity analysis revealed that the combined effect of a carbon tax (US$ 40/tCO 2), CO 2 sales price (US$ 40/tCO 2) and advanced configuration only led to a slight increase (2.6% for MEA and 2.1% for AMP-MEA blend) in the price of the northern bleached softwood kraft pulp. With an even better-performing solvent system and process configuration, the price of NBSK pulp may not be affected given the indicated CO 2 tax and CO 2 price regime. [ABSTRACT FROM AUTHOR]

The feasibility of stripping CO2 from anaerobic digester centrate (generated in a sludge dewatering process) to raise pH, and therefore reduce the cost of caustic chemical(s) dosage for similar operation in a struvite-recovery system, was investigated. A cascade CO2 stripper was installed in a pilot-scale, struvite-recovery reactor system at the Lulu Island Wastewater Treatment Plant, Richmond, British Columbia, Canada, as a replacement of part of (about 1/3) the reactor downpipe. Centrate was used as the process feed. Both the influent and the effluent from the struvite reactor were analyzed for pH, temperature (°C), and concentrations of Mg, NH4-N, and PO4-P. Results indicated that, by adding the CO2 stripper, caustic chemical savings was as much as 46%-65%. Moreover, because of the capability of the stripper in providing a more gradual pH increase, fewer fine solids were produced in the reactor than when caustic solution was used to raise the pH of the reactor. Nous examinons la faisabilité d'éliminer le CO2 d'un centrifugat d'un digesteur anaérobie (généré lors du procédé de déshydratation des boues) afin d'augmenter le pH et ainsi réduire le coût de dosage des produits chimiques caustiques pour une opération similaire dans un système de récupération de la struvite. Un nettoyeur de CO2 en cascade a été installé dans un système de réacteur de récupération de la struvite à l'échelle pilote à l'usine de traitement des eaux usées de Lulu Island, à Richmond, C.-B., pour remplacer environ le tiers du tuyau primaire du réacteur. Le centrifugat a été utilisé comme alimentation du procédé. L'influent et l'effluent du réacteur de struvite ont été analysés pour déterminer le pH, la température (°C) et les concentrations en Mg, NH4-N et PO4-P. Selon les résultats, l'ajout du nettoyeur de CO2 pouvait engendrer des économies en produits chimiques caustiques de 46 à 65 %. De plus, en raison de la capacité du nettoyeur à augmenter le pH plus graduellement, moins de solides fins ont été produits dans le réacteur que lorsqu'une solution caustique était utilisée pour augmenter le pH du réacteur. [ABSTRACT FROM AUTHOR]

Measures carbon dioxide fluxes from a five-year old vegetated clearcut in sub-boreal British Columbia using two different approaches. Share of conifer seedlings in overall carbon dioxide fluxes; Factors affecting divergence in the data; Main component of carbon dioxide fluxes.