CO2 Separation and Capture Properties of Porous Carbonaceous Materials from Leather Residues

Carbonaceous porous materials derived from leather skin residues have been found to have excellent CO₂ adsorption properties, with interestingly high gas selectivities for CO₂ (α > 200 at a gas composition of 15% CO₂/85% N₂, 273K, 1 bar) and capacities (>2 mmol·g⁻¹ at 273 K). Both CO₂ isotherms and the high heat of adsorption pointed to the presence of strong binding sites for CO₂ which may be correlated with both: N content in the leather residues and ultrasmall pore sizes.     

ZnO/Carbon Spheres with Excellent Regenerability for Post-Combustion CO2 Capture

This paper examines the synthesis of the ZnO/carbon spheres composites using resorcinol—formaldehyde resin as a carbon source and zinc nitrate as a zinc oxide source in a solvothermal reactor heated with microwaves. The influence of activation with potassium oxalate and modification with zinc nitrate on the physicochemical properties of the obtained materials and CO₂ adsorption capacity was investigated. It was found that in the case of nonactivated material as well as activated materials, the presence of zinc oxide in the carbon matrix had no effect or slightly increased the values of CO₂ adsorption capacity. Only for the material where the weight ratio of carbon:zinc was 2:1, the decrease of CO₂ adsorption capacity was reported. Additionally, CO₂ adsorption experiments on nonactivated carbon spheres and those activated with potassium oxalate with different amounts of zinc nitrate were carried out at 40 °C using thermobalance. The highest CO₂ adsorption capacity at temperature 40 °C (2.08 mmol/g adsorbent) was achieved for the material after activation with potassium oxalate with the highest zinc nitrate content as ZnO precursor. Moreover, repeated adsorption/desorption cycle experiments revealed that the as-prepared carbon spheres were very good CO₂ adsorbents, exhibiting excellent cyclic stability with a performance decay of less than 10% over up to 25 adsorption-desorption cycles.     

CO2 Adsorption on Activated Carbons Prepared from Molasses: A Comparison of Two and Three Parametric Models

Activated carbons with different textural characteristic were derived by the chemical activation of raw beet molasses with solid KOH, while the activation temperature was changed in the range 650 °C to 800 °C. The adsorption of CO₂ on activated carbons was investigated. Langmuir, Freundlich, Sips, Toth, Unilan, Fritz-Schlunder, Radke-Prausnitz, Temkin-Pyzhev, Dubinin-Radushkevich, and Jovanovich equations were selected to fit the experimental data of CO₂ adsorption. An error analysis (the sum of the squares of errors, the hybrid fractional error function, the average relative error, the Marquardt’s percent standard deviation, and the sum of the absolute errors) was conducted to examine the effect of using various error standards for the isotherm model parameter calculation. The best fit was observed to the Radke-Prausnitz model.     

Methylcellulose-Directed Synthesis of Nanocrystalline Zeolite NaA with High CO2 Uptake

Zeolite NaA nanocrystals with a narrow particle size distribution were prepared by template-free hydrothermal synthesis in thermo-reversible methylcellulose gels. The effects of the amount of methylcellulose, crystallization time and hydrothermal treatment temperature on the crystallinity and particle size distribution of the zeolite NaA nanocrystals were investigated. We found that the thermogelation of methylcellulose in the alkaline Na₂O-SiO₂-Al₂O₃-H₂O system played an important role in controlling the particle size. The synthesized zeolite nanocrystals are highly crystalline, as demonstrated by X-ray diffraction (XRD), and scanning electron microscopy (SEM) shows that the nanocrystals can also display a well-defined facetted morphology. Gas adsorption studies on the synthesized nanocrystalline zeolite NaA showed that nanocrystals with a size of 100 nm displayed a high CO₂ uptake capacity (4.9 mmol/g at 293 K at 100 kPa) and a relatively rapid uptake rate compared to commercially available, micron-sized particles. Low-cost nanosized zeolite adsorbents with a high and rapid uptake are important for large scale gas separation processes, e.g., carbon capture from flue gas.     

The urgency of the development of CO2 capture from ambient air

CO(2) capture and storage (CCS) has the potential to develop into an important tool to address climate change. Given society's present reliance on fossil fuels, widespread adoption of CCS appears indispensable for meeting stringent climate targets. We argue that for conventional CCS to become a successful climate mitigation technology-which by necessity has to operate on a large scale-it may need to be complemented with air capture, removing CO(2) directly from the atmosphere. Air capture of CO(2) could act as insurance against CO(2) leaking from storage and furthermore may provide an option for dealing with emissions from mobile dispersed sources such as automobiles and airplanes.     

Covalent Triazine Frameworks Based on the First Pseudo-Octahedral Hexanitrile Monomer via Nitrile Trimerization: Synthesis,Porosity, and CO2 Gas Sorption Properties

Herein, we report the first synthesis of covalent triazine-based frameworks (CTFs) based on a hexanitrile monomer, namely the novel pseudo-octahedral hexanitrile 1,4-bis(tris(4′-cyano-phenyl)methyl)benzene 1 using both ionothermal reaction conditions with ZnCl₂ at 400 °C and the milder reaction conditions with the strong Brønsted acid trifluoromethanesulfonic acid (TFMS) at room temperature. Additionally, the hexanitrile was combined with different di-, tri-, and tetranitriles as a second linker based on recent work of mixed-linker CTFs, which showed enhanced carbon dioxide captures. The obtained framework structures were characterized via infrared (IR) spectroscopy, elemental analysis, scanning electron microscopy (SEM), and gas sorption measurements. Nitrogen adsorption measurements were performed at 77 K to determine the Brunauer-Emmett-Teller (BET) surface areas range from 493 m²/g to 1728 m²/g (p/p₀ = 0.01–0.05). As expected, the framework CTF-hex6 synthesized from 1 with ZnCl₂ possesses the highest surface area for nitrogen adsorption. On the other hand, the mixed framework structure CTF-hex4 formed from the hexanitrile 1 and 1,3,5 tricyanobenzene (4) shows the highest uptake of carbon dioxide and methane of 76.4 cm³/g and 26.6 cm³/g, respectively, at 273 K.     

Safe storage and effective monitoring of CO2 in depleted gas fields

Carbon capture and storage (CCS) is vital to reduce CO(2) emissions to the atmosphere, potentially providing 20% of the needed reductions in global emissions. Research and demonstration projects are important to increase scientific understanding of CCS, and making processes and results widely available helps to reduce public concerns, which may otherwise block this technology. The Otway Project has provided verification of the underlying science of CO(2) storage in a depleted gas field, and shows that the support of all stakeholders can be earned and retained. Quantitative verification of long-term storage has been demonstrated. A direct measurement of storage efficiency has been made, confirming that CO(2) storage in depleted gas fields can be safe and effective, and that these structures could store globally significant amounts of CO(2).     

Disentangling the effects of CO2 and short-lived climate forcer mitigation

Anthropogenic global warming is driven by emissions of a wide variety of radiative forcers ranging from very short-lived climate forcers (SLCFs), like black carbon, to very long-lived, like CO₂. These species are often released from common sources and are therefore intricately linked. However, for reasons of simplification, this CO₂–SLCF linkage was often disregarded in long-term projections of earlier studies. Here we explicitly account for CO₂–SLCF linkages and show that the short- and long-term climate effects of many SLCF measures consistently become smaller in scenarios that keep warming to below 2 °C relative to preindustrial levels. Although long-term mitigation of methane and hydrofluorocarbons are integral parts of 2 °C scenarios, early action on these species mainly influences near-term temperatures and brings small benefits for limiting maximum warming relative to comparable reductions taking place later. Furthermore, we find that maximum 21st-century warming in 2 °C-consistent scenarios is largely unaffected by additional black-carbon-related measures because key emission sources are already phased-out through CO₂ mitigation. Our study demonstrates the importance of coherently considering CO₂–SLCF coevolutions. Failing to do so leads to strongly and consistently overestimating the effect of SLCF measures in climate stabilization scenarios. Our results reinforce that SLCF measures are to be considered complementary rather than a substitute for early and stringent CO₂ mitigation. Near-term SLCF measures do not allow for more time for CO₂ mitigation. We disentangle and resolve the distinct benefits across different species and therewith facilitate an integrated strategy for mitigating both short and long-term climate change.For about two decades, policy-makers have considered options to avoid dangerous anthropogenic interference with the climate system (1). So far, many countries support limiting warming to below a 2 °C temperature limit, but the required global mitigation action to achieve this has been limited (2–4). To inform policy-makers about options and challenges, the United Nations Environment Program (UNEP) published several reports over the past years on three interlinked aspects: climate stabilization and greenhouse gas (GHG) mitigation (3), short-lived climate forcers (SLCFs) and clean-air benefits (5, 6), and hydrofluorocarbons (7) (HFCs). We build here upon the insights of these reports (henceforth referred to as “Gap Report,” “SLCF Reports,” and “HFC Report,” respectively) to disentangle the joint effects of CO₂ and SLCF mitigation for limiting global warming. We evaluate the potential for limiting global-mean warming until 2100 and the rate of near-term warming, with a focus on 2 °C-consistent scenarios (Fig. 1). Reductions in CO₂ and SLCFs also provide important cobenefits like energy security (8), and local health and agricultural benefits (9–12), which fall outside the scope of this paper.Open in a separate windowFig. 1.Influence of SLCF-CO₂ linkages under varying CO₂ mitigation. (A) Global-mean surface temperature implications and interdependence of CO₂ (black), CH₄ (green), HFC (orange), BC-related (blue), and SO₂ mitigation (red). (B) The general effect of SLCF-CO₂ linkages. CO₂ paths show a world “with CO₂ mitigation” (32) and with “no CO₂ mitigation” (24). Early CH₄ mitigation is represented by the combined light and dark green area. HFC mitigation is shown for the lower end of the range assessed in this study. BC-related (and SO₂) measures show the difference between Case 6 and Case 2 (Case 4 and Case 2). Alternative cases are provided in SI Appendix, Fig. S1. Vertical dashed lines are time points relevant to Figs. 2 and ​and33.The main challenge in this exercise is the interdependence of coemitted climate forcers and the differences between their net forcing effects (13). For example, energy-related black carbon (BC) aerosols have an overall warming effect (14), whereas sulfate aerosols and some biomass-related BC emissions together with their coemitted species are cooling (13, 14). Because CO₂ and BC-related emissions often have common combustion sources (14), CO₂ mitigation will also influence the abundance of SLCFs. This linkage has already been well studied for other air pollutants (15, 16). Due to data limitations, the first studies that analyzed the mitigation potential of SLCFs (5, 6, 9, 17–19) did not account for these linkages in the long term and kept post-2030 SLCF forcing constant across a wide range of CO₂ paths. Alternatively, simple relationships between species were used (20). Such approaches, however, cannot guarantee that the long-term SLCF and CO₂ evolutions remain internally consistent. To provide an integrated view, we here account for this linkage and apply relationships (21) derived from detailed energy–environment–economy scenarios that explore various levels of air pollution control and track technological linkages between SCLF and CO₂ sources (8). Each CO₂ scenario in our analysis is thus associated with a consistent evolution of SLCFs at a specific level of pollution control stringency (see below). In policy discussions, methane (CH₄) and BC are often subsumed under the single term “short-lived climate pollutants” (SLCP) but in light of their different influence on the climate, as well as differing technological and policy instruments for mitigation, they are explicitly distinguished here.     

Functional Materials Based on Active Carbon and Titanium Dioxide in Fog Seal

Due to its ability to degrade nitrogen oxides under ultraviolet, titanium dioxide has been applied in asphalt concrete to degrade automobile exhaust in recent years. To highlight the protection of road traffic environmental quality and mitigate automobile exhaust on human health, this study proposes combining titanium dioxide and active carbon into Sand-fog seal to form a pavement coating material with a photocatalytic function. It uses active carbon to reinforce the material’s function, and the coupling agent for modification makes it well dispersed in the Sand-fog seal. The indoor experiments were carried out at 30 °C and relative humidity of 30%. It tested the composite material’s degradation efficiency on nitrogen dioxide in relation to component proportions, coupling agents, and dosages. The study concluded that the optimal photocatalytic efficiency could be achieved when the ratio of active carbon to titanium dioxide is 0.6. After being modified by the titanate coupling agent and through Scanning Electron Microscope tests, it can be seen that materials can be well dispersed into the Sand-fog seal. When the composite material accounts for 10% of the fog seal, it can achieve the optimal photocatalytic efficiency of about 23.9%. The British pendulum tests show it has good skid resistance performance. Half a kilometer of concrete roadway was sprayed with the material coating in Tianjin, China. The photocatalytic experimental road degrades nitrogen oxides better than the original road. The method is feasible for practical implementation.     

Feedbacks and the coevolution of plants and atmospheric CO2

The coupled evolution of land plants, CO2, and climate over the last half billion years has maintained atmospheric CO2 concentrations within finite limits, indicating the involvement of a complex network of geophysiological feedbacks. But insight into this important regulatory network is extremely limited. Here we present a systems analysis of the physiological and geochemical processes involved, identifying new positive and negative feedbacks between plants and CO2 on geological time scales. Positive feedbacks accelerated falling CO2 concentrations during the evolution and diversification of terrestrial ecosystems in the Paleozoic and enhanced rising CO2 concentrations across the Triassic-Jurassic boundary during flood basalt eruptions. The existence of positive feedbacks reveals the unexpected destabilizing influence of the biota in climate regulation that led to environmental modifications accelerating rates of terrestrial plant and animal evolution in the Paleozoic.     

Ionic Liquids and Deep Eutectic Solvents for CO2 Conversion Technologies—A Review

Ionic liquids (ILs) have a wide range of potential uses in renewable energy, including CO₂ capture and electrochemical conversion. With the goal of providing a critical overview of the progression, new challenges, and prospects of ILs for evolving green renewable energy processes, this review emphasizes the significance of ILs as electrolytes and reaction media in two primary areas of interest: CO₂ electroreduction and organic molecule electrosynthesis via CO₂ transformation. Herein, we briefly summarize the most recent advances in the field, as well as approaches based on the electrochemical conversion of CO₂ to industrially important compounds employing ILs as an electrolyte and/or reaction media. In addition, the review also discusses the advances made possible by deep eutectic solvents (DESs) in CO₂ electroreduction to CO. Finally, the critical techno-commercial issues connected with employing ILs and DESs as an electrolyte or ILs as reaction media are reviewed, along with a future perspective on the path to rapid industrialization.     

Structure of the alpha2epsilon2 Ni-dependent CO dehydrogenase component of the Methanosarcina barkeri acetyl-CoA decarbonylase/synthase complex

Ni-dependent carbon monoxide dehydrogenases (Ni-CODHs) are a diverse family of enzymes that catalyze reversible CO:CO(2) oxidoreductase activity in acetogens, methanogens, and some CO-using bacteria. Crystallography of Ni-CODHs from CO-using bacteria and acetogens has revealed the overall fold of the Ni-CODH core and has suggested structures for the C cluster that mediates CO:CO(2) interconversion. Despite these advances, the mechanism of CO oxidation has remained elusive. Herein, we report the structure of a distinct class of Ni-CODH from methanogenic archaea: the alpha(2)epsilon(2) component from the alpha(8)beta(8)gamma(8)delta(8)epsilon(8) CODH/acetyl-CoA decarbonylase/synthase complex, an enzyme responsible for the majority of biogenic methane production on Earth. The structure of this Ni-CODH component provides support for a hitherto unobserved state in which both CO and H(2)O/OH(-) bind to the Ni and the exogenous FCII iron of the C cluster, respectively, and offers insight into the structures and functional roles of the epsilon-subunit and FeS domain not present in nonmethanogenic Ni-CODHs.     

Direct electrolytic dissolution of silicate minerals for air CO2 mitigation and carbon-negative H2 production

We experimentally demonstrate the direct coupling of silicate mineral dissolution with saline water electrolysis and H₂ production to effect significant air CO₂ absorption, chemical conversion, and storage in solution. In particular, we observed as much as a 10⁵-fold increase in OH⁻ concentration (pH increase of up to 5.3 units) relative to experimental controls following the electrolysis of 0.25 M Na₂SO₄ solutions when the anode was encased in powdered silicate mineral, either wollastonite or an ultramafic mineral. After electrolysis, full equilibration of the alkalized solution with air led to a significant pH reduction and as much as a 45-fold increase in dissolved inorganic carbon concentration. This demonstrated significant spontaneous air CO₂ capture, chemical conversion, and storage as a bicarbonate, predominantly as NaHCO₃. The excess OH⁻ initially formed in these experiments apparently resulted via neutralization of the anolyte acid, H₂SO₄, by reaction with the base mineral silicate at the anode, producing mineral sulfate and silica. This allowed the NaOH, normally generated at the cathode, to go unneutralized and to accumulate in the bulk electrolyte, ultimately reacting with atmospheric CO₂ to form dissolved bicarbonate. Using nongrid or nonpeak renewable electricity, optimized systems at large scale might allow relatively high-capacity, energy-efficient (<300 kJ/mol of CO₂ captured), and inexpensive (<$100 per tonne of CO₂ mitigated) removal of excess air CO₂ with production of carbon-negative H₂. Furthermore, when added to the ocean, the produced hydroxide and/or (bi)carbonate could be useful in reducing sea-to-air CO₂ emissions and in neutralizing or offsetting the effects of ongoing ocean acidification.     

Economic and energetic analysis of capturing CO2 from ambient air

Capturing carbon dioxide from the atmosphere (“air capture”) in an industrial process has been proposed as an option for stabilizing global CO₂ concentrations. Published analyses suggest these air capture systems may cost a few hundred dollars per tonne of CO₂, making it cost competitive with mainstream CO₂ mitigation options like renewable energy, nuclear power, and carbon dioxide capture and storage from large CO₂ emitting point sources. We investigate the thermodynamic efficiencies of commercial separation systems as well as trace gas removal systems to better understand and constrain the energy requirements and costs of these air capture systems. Our empirical analyses of operating commercial processes suggest that the energetic and financial costs of capturing CO₂ from the air are likely to have been underestimated. Specifically, our analysis of existing gas separation systems suggests that, unless air capture significantly outperforms these systems, it is likely to require more than 400 kJ of work per mole of CO₂, requiring it to be powered by CO₂-neutral power sources in order to be CO₂ negative. We estimate that total system costs of an air capture system will be on the order of $1,000 per tonne of CO₂, based on experience with as-built large-scale trace gas removal systems.     

Impact of Biochar Addition and Air-Flow Rate on Ammonia and Carbon Dioxide Concentration in the Emitted Gases from Aerobic Biostabilization of Waste

Application of additives to waste may influence the course of the biostabilization process and contribute to its higher effectiveness, as well as to a reduction in greenhouse gas and ammonia (NH₃) emission from this process. This paper presents research on the impact of biochar addition on the course of the biostabilization process of an undersized fraction from municipal solid waste (UFMSW) in terms of temperature changes, CO₂ concentration in the exhaust gases, NH₃ emission from the process, as well as changes in the carbon and nitrogen content in the processed waste. Six different biochar additives and three different air-flow rates were investigated for 21 days. It was found that biochar addition contributes to extending the thermophilic phase duration (observed in the case of the addition of 3% and 5% of biochar). The concentration of CO₂ in exhaust gases was closely related to the course of temperature changes. The highest concentration of CO₂ in the process gases (approx. 18–19%) was recorded for the addition of 10% and 20% of biochar at the lowest air-flow rate applied. It was found that the addition of 3% or a higher amount of biochar reduces nitrogen losses in the processed UFMSW and reduces NH₃ emission by over 90% compared to the control.     

Cities,traffic, and CO2: A multidecadal assessment of trends,drivers, and scaling relationships

Emissions of CO₂ from road vehicles were 1.57 billion metric tons in 2012, accounting for 28% of US fossil fuel CO₂ emissions, but the spatial distributions of these emissions are highly uncertain. We develop a new emissions inventory, the Database of Road Transportation Emissions (DARTE), which estimates CO₂ emitted by US road transport at a resolution of 1 km annually for 1980–2012. DARTE reveals that urban areas are responsible for 80% of on-road emissions growth since 1980 and for 63% of total 2012 emissions. We observe nonlinearities between CO₂ emissions and population density at broad spatial/temporal scales, with total on-road CO₂ increasing nonlinearly with population density, rapidly up to 1,650 persons per square kilometer and slowly thereafter. Per capita emissions decline as density rises, but at markedly varying rates depending on existing densities. We make use of DARTE’s bottom-up construction to highlight the biases associated with the common practice of using population as a linear proxy for disaggregating national- or state-scale emissions. Comparing DARTE with existing downscaled inventories, we find biases of 100% or more in the spatial distribution of urban and rural emissions, largely driven by mismatches between inventory downscaling proxies and the actual spatial patterns of vehicle activity at urban scales. Given cities’ dual importance as sources of CO₂ and an emerging nexus of climate mitigation initiatives, high-resolution estimates such as DARTE are critical both for accurately quantifying surface carbon fluxes and for verifying the effectiveness of emissions mitigation efforts at urban scales.The United States, with 5% of the world’s population and 30% of the world’s automobiles, emits 45% of global transportation CO₂ emissions (1). Nationally, the on-road sector represented 28% of total fossil fuel CO₂ emissions in 2012 and is responsible for almost half of the growth in total US emissions since 1990 (2). Despite being a substantial component of US emissions, on-road CO₂ remains poorly quantified at substate and urban scales (3–5). Reducing the uncertainty of on-road CO₂ emissions at finer spatial scales is critical to understanding the determinants of motor vehicle emissions (3), constraining carbon budgets (4), and supporting greenhouse gas (GHG) emission monitoring and abatement verification (5), particularly at the scale of cities, which have emerged as hubs of climate change mitigation activity (6).Carbon cycle models now operate at resolutions much finer than US states, and their reliance on gridded inventories for a priori estimates of the spatial distribution of emissions (7–9) means that raw emissions data available at coarse spatial scales must be “downscaled” to match model grids. Increasing the spatial resolution of emission inventories has been shown to change modeled terrestrial carbon flux estimates by more than 50% (8). The notion that population density is a robust predictor of CO₂ emissions underpins most gridded global emissions estimates (10–14). Early studies used maps of population density to distribute national CO₂ emissions on a global 1° grid, assuming uniform per capita emissions within each country (10, 11). This assumption was shown to be invalid for the United States, where per capita emissions vary by an order of magnitude across states (12). Population becomes an even less reliable predictor of total CO₂ emissions at finer scales, where local patterns of concentrated point and line sources dominate over more diffuse area sources (3, 13). Used alone, population may be a valid predictor for residential and commercial sector emissions, but it performs poorly when used to model emissions from power stations or the on-road sector (3, 4, 13). Recent global inventories, such as the Fossil Fuel Data Assimilation System, partially correct for this deviation by modeling power plant emissions directly as point sources, although on-road emissions are still spatially allocated using population and luminosity data (15). The Emissions Database for Global Atmospheric Research (EDGAR, version 4.2) used a wide variety of sector-specific variables to allocate national CO₂ emissions onto a 0.1° global grid (14), but it used only road density to distribute emissions spatially (16). In the United States, there is substantial variation in the intensity of vehicle activity per mile of roadway, as well as considerable differences in the fleet composition and fuel economy of vehicles that travel on different functional classes of roads (17–19).A multivariate regression framework that broadens the number of proxies to incorporate demographic, socioeconomic, and built-environment variables appears to improve the spatial accuracy of predicted emissions. Individuals’ vehicle travel was found to be best predicted by household income, vehicle ownership, and commuting distance, and the estimated relationships have been used to impute on-road emissions at the zip code level (20). Directly measured roadway CO₂ concentrations have also been parsimoniously modeled using only the local fraction of impervious surface and a traffic volume-weighted road density index (21). In selected US states and cities, local traffic count data and state-level fuel consumption have been used to downscale emissions to a 500-m grid (22).Most of these studies relied on cross-sectional data, which means that the temporal stability of their results remains untested. This issue is important for addressing the enduring question in urban sustainability of how trends in urban sprawl and densification affect individuals’ travel behavior and related CO₂ emissions over time (23–25). Population density is not thought to affect travel behavior directly, but it is a proxy for less easily measured characteristics of the urban environment [e.g., public transit availability, walkability, amenity access (26, 27)] whose impacts on travel have long been a focus of regional and urban planning research. A classic example is the exponential decline in per capita transportation energy use with increasing population density that was observed in a large cross-section of cities worldwide (28). This relationship suggests that urban densification reduces per capita emissions, an idea that has gone on to influence urban development and sustainability initiatives worldwide. Despite recent advances in this area (29, 30), there remains a fundamental simultaneity that confounds inferences about the density–emissions relationship: Individuals’ travel behavior is affected by the built environment context of their place of residence, but their choice of residential location is simultaneously influenced by their travel preferences (31).To unravel the joint spatial and temporal covariation between multiple predictors and emissions, we constructed a new, dynamic, process-based emissions inventory. The Database of Road Transportation Emissions (DARTE) is an annual 1-km resolution CO₂ emissions inventory for the US on-road transportation sector, based on archived data of roadway-level vehicle traffic for the years 1980–2012. Raw vehicle activity data were obtained from the Federal Highway Administration’s (FHWA’s) Highway Performance Monitoring System (HPMS), a database of road-level traffic counts derived from annual reporting by all US state transportation departments (32). The availability of source activity data at this resolution enabled us to estimate vehicle emissions directly at the scale of individual road segments without the need to downscale emissions using spatial predictors. We combined HPMS roadway-level vehicle miles traveled (VMT) with year- and state-specific emissions factors for five vehicle types to calculate CO₂ emissions from motor gasoline and diesel fuel consumption on six classes of urban and rural roads. We then used DARTE to quantify the spatiotemporally varying effects of population density, income, employment, and transit use on on-road CO₂ emissions across the United States. We also characterize multidecadal trends in emissions across all rural and urban road types, finding an increasing dominance of urban emissions across the United States. Finally, we compared DARTE with several existing inventories of on-road CO₂ emissions and identified large relative biases in emissions estimates, with differences that exceed 500% for several major US metropolitan areas.     

Assessing the health risks of natural CO2 seeps in Italy

Industrialized societies which continue to use fossil fuel energy sources are considering adoption of Carbon Capture and Storage (CCS) technology to meet carbon emission reduction targets. Deep geological storage of CO(2) onshore faces opposition regarding potential health effects of CO(2) leakage from storage sites. There is no experience of commercial scale CCS with which to verify predicted risks of engineered storage failure. Studying risk from natural CO(2) seeps can guide assessment of potential health risks from leaking onshore CO(2) stores. Italy and Sicily are regions of intense natural CO(2) degassing from surface seeps. These seeps exhibit a variety of expressions, characteristics (e.g., temperature/flux), and location environments. Here we quantify historical fatalities from CO(2) poisoning using a database of 286 natural CO(2) seeps in Italy and Sicily. We find that risk of human death is strongly influenced by seep surface expression, local conditions (e.g., topography and wind speed), CO(2) flux, and human behavior. Risk of accidental human death from these CO(2) seeps is calculated to be 10-8 year-1 to the exposed population. This value is significantly lower than that of many socially accepted risks. Seepage from future storage sites is modeled to be less that Italian natural flux rates. With appropriate hazard management, health risks from unplanned seepage at onshore storage sites can be adequately minimized.     

Efficiency of DNA Isolation Methods Based on Silica Columns and Magnetic Separation Tested for the Detection of Mycobacterium avium Subsp. Paratuberculosis in Milk and Faeces

Timely and reliable detection of animals shedding Mycobacterium avium subsp. paratuberculosis (MAP) should help to effectively identify infected animals and limit infection transmission at early stages to ensure effective control of paratuberculosis. The aim of the study was to compare DNA extraction methods and evaluate isolation efficiency using milk and faecal samples artificially contaminated by MAP with a focus on modern instrumental automatic DNA isolation procedures based on magnetic separation. In parallel, an automatic and manual version of magnetic separation and two methods of faecal samples preparation were compared. Commercially available DNA isolation kits were evaluated, and the selected kits were used in a trial of automatic magnetic beads-based isolation and compared with the manual version of each kit. Detection of the single copy element F57 was performed by qPCR to quantify MAP and determine the isolation efficiency. The evaluated kits showed significant differences in DNA isolation efficiencies. The best results were observed with the silica column Blood and Tissue kit for milk and Zymo Research for faeces. The highest isolation efficiency for magnetic separation was achieved with MagMAX for both matrices. The magnetic separation and silica column isolation methods used in this study represent frequently used methods in mycobacterial diagnostics.