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This article, the eighth in the series, presents kinetic and photochemical data sheets evaluated by the IUPAC Task Group on Atmospheric Chemical Kinetic Data Evaluation. It covers the gas-phase thermal and photochemical reactions of organic species with four, or more, carbon atoms (≥ C4) available on the IUPAC website in 2021, including thermal reactions of closed-shell organic species with HO and NO3 radicals and their photolysis. The present work is a continuation of volume II (Atkinson et al., 2006), with new reactions and updated data sheets for reactions of HO (77 reactions) and NO3 (36 reactions) with ≥ C4 organics, including alkanes, alkenes, dienes, aromatics, oxygenated, organic nitrates and nitro compounds in addition to photochemical processes for nine species. The article consists of a summary table (Table 1), containing the recommended kinetic parameters for the evaluated reactions, and a supplement containing the data sheets, which provide information upon which recommendations are made.

Ethanol blending into gasoline yields a wide range of octane rating responses, most frequently synergistic (i.e., greater than expected by linear blending), but also linear or antagonistic. A new a...

Smog chamber/FTIR techniques were used to investigate the kinetics and mechanism of the Cl atom and OH radical initiated oxidation of 2,2-dichloroethanol at (296 ± 1) K. Relative rate methods were used to measure k(Cl + CHCl2CH2OH) = (5.87 ± 0.96) × 10-12 and k(OH + CHCl2CH2OH) = (5.54 ± 1.94) × 10-13 cm3 molecule-1 s-1. Chlorine atom initiated oxidation of CHCl2CH2OH in one atmosphere of air gives HCOCl, CHCl2CHO, and COCl2 in yields of (62 ± 5)%, (39 ± 10)%, and (8 ± 2)%, respectively. The rate constant k(Cl + CHCl2CHO) = (8.3 ± 16) × 10-12 cm3 molecule-1 s-1 was determined and the IR spectra of CHCl2CHO is reported for the first time. The atmospheric lifetime for CHCl2CH2OH is estimated as 21 days. The experimental results are discussed in the context of the atmospheric chemistry of chlorinated alcohols.

The reaction of perfluorooctanoic acid with the smallest carbonyl oxide Criegee intermediate, CH2OO, has been measured and is very rapid, with a rate coefficient of (4.9 ± 0.8) × 10-10 cm3 s-1, similar to that for reactions of Criegee intermediates with other organic acids. Evidence is shown for the formation of hydroperoxymethyl perfluorooctanoate as a product. With such a large rate coefficient, reaction with Criegee intermediates can be a substantial contributor to atmospheric removal of perfluorocarboxylic acids. However, the atmospheric fates of the ester product largely regenerate the initial acid reactant. Wet deposition regenerates the perfluorocarboxylic acid via condensed-phase hydrolysis. Gas-phase reaction with OH is expected principally to result in formation of the acid anhydride, which also hydrolyzes to regenerate the acid, although a minor channel could lead to destruction of the perfluorinated backbone.

The term open-air factor (OAF) was coined following microbiological research in the 1960s and 1970s which established that rural air had powerful germicidal properties and attributed this to Criegee intermediates formed in the reaction of ozone with alkenes. We have re-evaluated those early experiments applying the current state of knowledge of ozone–alkene reactions. Contrary to previous speculation, neither Criegee intermediates nor the HO radicals formed in their decomposition are directly responsible for the germicidal activity attributed to the OAF. We identify other potential candidates, which are formed in ozone–alkene reactions and have known (and likely) germicidal properties, but the compounds responsible for the OAF remain a mystery. There has been very little research into the OAF since the 1970s, and this effect seems to have been largely forgotten. In this opinion piece we remind the community of the germicidal open-air factor. Given the current global pandemic spread by an airborne pathogen, understanding the natural germicidal effects of ambient air, solving the mystery of the open-air factor and determining how this effect can be used to improve human welfare should be a high priority for the atmospheric science community.

Expanded use of novel oil extraction technologies has increased the variability of petroleum resources and diversified the carbon footprint of the global oil supply1. Past life-cycle assessment (LCA) studies overlooked upstream emission heterogeneity by assuming that a decline in oil demand will displace average crude oil2. We explore the life-cycle greenhouse gas emissions impacts of marginal crude sources, identifying the upstream carbon intensity (CI) of the producers most sensitive to an oil demand decline (for example, due to a shift to alternative vehicles). We link econometric models of production profitability of 1,933 oilfields (~90% of the 2015 world supply) with their production CI. Then, we examine their response to a decline in demand under three oil market structures. According to our estimates, small demand shocks have different upstream CI implications than large shocks. Irrespective of the market structure, small shocks (−2.5% demand) displace mostly heavy crudes with ~25–54% higher CI than that of the global average. However, this imbalance diminishes as the shocks become bigger and if producers with market power coordinate their response to a demand decline. The carbon emissions benefits of reduction in oil demand are systematically dependent on the magnitude of demand drop and the global oil market structure. Here the non-linear relationship is revealed between carbon emissions reductions and oil demand reductions, which depends on the magnitude of demand drop and the global oil market structure.

Oil production choices are influenced by the interaction of oilfield production costs and the global price of oil. What are the characteristics of less economic oilfields, fields whose profitably is at the margin? These oilfields may differ from average fields in terms of geographical location, crude type, production practices, and carbon intensity (CI). Because these economically-marginal fields are the ones likely to respond to drop in demand (e.g., due to 2020 COVID-19 pandemic, or a rapid shift to alternatives), they represent the likely sources of oil that would be displaced. The present paper links the field-by-field costs of 1933 oilfields (representing ~ 90% of 2015 worldwide crude production) with their production environmental footprint. We show that many marginal fields also have high CI. We estimate that the fields at margin due to the 2020 COVID-19 pandemic demand reduction have upstream CI and marginal cost of production ~ 35% and 3 times higher than global average, respectively. The production termination of these fields could result in 181 Mtonne CO2Eq. annual reduction in upstream emissions in the short-term. The marginal producers in a generic small demand shock (5% or ~ 3.6 mmbbl/d drop) have an upstream CI 26% higher than average global oil producers, and at our larger generic demand shock (20% or ~ 14.3 mmbbl/d drop) have CI that is 5% higher than average. Heavy oilfields have the highest volume share in marginal crudes in all scenarios. These results further suggest that life cycle benefits of alternative fuels or vehicles or regulations that lead to reduced oil consumption are systematically larger than those typically estimated when displaced emissions are modeled using average crudes. The results only cover the upstream production CI and do not include synergistic impacts of differences in refining CI of different types of crudes, and thus could underestimate the total life cycle differences between marginal and average crudes.

This article, the seventh in the series, presents kinetic and photochemical data sheets evaluated by the IUPAC Task Group on Atmospheric Chemical Kinetic Data Evaluation. It covers an extension of the gas-phase and photochemical reactions related to Criegee intermediates previously published in Atmospheric Chemistry and Physics (ACP) in 2006 and implemented on the IUPAC website up to 2020. The article consists of an introduction, description of laboratory measurements, a discussion of rate coefficients for reactions of O3 with alkenes producing Criegee intermediates, rate coefficients of unimolecular and bimolecular reactions and photochemical data for reactions of Criegee intermediates, and an overview of the atmospheric chemistry of Criegee intermediates. Summary tables of the recommended kinetic and mechanistic parameters for the evaluated reactions are provided. Data sheets summarizing information upon which the recommendations are based are given in two files, provided as a Supplement to this article.

Our understanding of the processes that control the burden and budget of tropospheric ozone has changed dramatically over the last 60 years. Models are the key tools used to understand these changes, and these underscore that there are many processes important in controlling the tropospheric ozone budget. In this critical review, we assess our evolving understanding of these processes, both physical and chemical. We review model simulations from the International Global Atmospheric Chemistry Atmospheric Chemistry and Climate Model Intercomparison Project and Chemistry Climate Modelling Initiative to assess the changes in the tropospheric ozone burden and its budget from 1850 to 2010. Analysis of these data indicates that there has been significant growth in the ozone burden from 1850 to 2000 (approximately 43 ± 9%) but smaller growth between 1960 and 2000 (approximately 16 ± 10%) and that the models simulate burdens of ozone well within recent satellite estimates. The Chemistry Climate Modelling Initiative model ozone budgets indicate that the net chemical production of ozone in the troposphere plateaued in the 1990s and has not changed since then inspite of increases in the burden. There has been a shift in net ozone production in the troposphere being greatest in the northern mid and high latitudes to the northern tropics, driven by the regional evolution of precursor emissions. An analysis of the evolution of tropospheric ozone through the 21st century, as simulated by Climate Model Intercomparison Project Phase 5 models, reveals a large source of uncertainty associated with models themselves (i.e., in the way that they simulate the chemical and physical processes that control tropospheric ozone). This structural uncertainty is greatest in the near term (two to three decades), but emissions scenarios dominate uncertainty in the longer term (2050–2100) evolution of tropospheric ozone. This intrinsic model uncertainty prevents robust predictions of near-term changes in the tropospheric ozone burden, and we review how progress can be made to reduce this limitation.

Aging of soybean biodiesel at an elevated temperature (90 °C) with aeration, simulating diesel engine fuel system conditions, yielded higher molecular weight materials and increased kinematic visco...

This perspective gives our views on general aspects and future directions of gas‐phase atmospheric chemical kinetic mechanism development, emphasizing on the work needed for the sustainable development of chemically detailed mechanisms that reflect current kinetic, mechanistic, and theoretical knowledge. Current and future mechanism development efforts and research needs are discussed, including software‐aided autogeneration and maintenance of kinetic models as a future‐proof approach for atmospheric model development. There is an overarching need for the evaluation and extension of structure‐activity relationships (SARs) that predict the properties and reactions of the many multifunctionalized compounds in the atmosphere that are at the core of detailed mechanisms, but for which no direct chemical data are available. Here, we discuss the experimental and theoretical data needed to support the development of mechanisms and SARs, the types of SARs relevant to atmospheric chemistry, the current status and limitations of SARs for various types of atmospheric reactions, the status of thermochemical estimates needed for mechanism development, and our outlook for the future. The authors have recently formed a SAR evaluation working group to address these issues.

The chemical mechanisms of the OH radical, Cl-atom and O3 initiated oxidation of (Z)-CF3CH[double bond, length as m-dash]CHCl were studied at 296 ± 1 K in 10-700 Torr air of N2/O2 diluent. Cl atoms add to the [double bond splayed left]C[double bond, length as m-dash]C[double bond splayed right] double bond: 12 ± 5% to the terminal carbon and 85 ± 5% to the central carbon. In 700 Torr of air the products are CF3CHClCHO, HCOCl, CF3COCl, CF3CHO, (E)-CF3CH[double bond, length as m-dash]CHCl, CF3C(O)CHCl2, and CF3CHClCOCl. The yield of (E) isomer was dependent on total pressure, but independent of O2 partial pressure; consistent with isomerization occurring via Cl atom elimination from the chemically activated rather than the thermalized CF3CHCHCl-Cl adduct. The rate constant for (Z)-CF3CH[double bond, length as m-dash]CHCl + Cl was measured at low pressure (10-15 Torr) and found to be indistinguishable from that determined at 700 Torr total pressure, whereas the low pressure rate constant for (E)-CF3CH[double bond, length as m-dash]CHCl was 36% smaller. G4MP2 ab initio calculations showed that the (E) isomer is 1.2 kcal mol-1 more stable than the (Z) isomer. Cl atom elimination from the adduct will preferentially form the (E) isomer and hence the rate of CF3CH[double bond, length as m-dash]CHCl loss will be more sensitive to pressure for the (Z) than the (E) isomer. Reaction of (Z)-CF3CH[double bond, length as m-dash]CHCl with OH radicals gives CF3CHO, HCOCl, (E)-CF3CH[double bond, length as m-dash]CHCl, and HCl. A significant chlorine atom elimination channel was observed experimentally, and supported by computational results. The oxidation products of the reaction of O3 with (Z)- and (E)-CF3CH[double bond, length as m-dash]CHCl were determined with no evidence of isomerization. The results are discussed with respect to the atmospheric chemistry and environmental impact of (Z)- and (E)-CF3CH[double bond, length as m-dash]CHCl.

Fuels in modern diesel engine fuel systems are exposed to highly oxidizing conditions, thus it is important to understand their degradation mechanisms. A range of chemical and physical properties was monitored during the oxidation and polymerization of soybean methyl ester biodiesel (B100), a diesel fuel (B0), and their blends (B10, B30) at 90 °C with aeration. The initial rapid oxidation of polyunsaturated fatty acid methyl esters (FAMEs) provided a transient pool of peroxides that led to the formation of aldehydes, ketones, and acids as secondary products. Monounsaturated and saturated FAMEs were oxidized concurrently with polyunsaturated FAMEs in B10, B30, and B100, but only B100 showed significant oxidation reactions continuing after the polyunsaturated FAMEs were depleted. New esters were a major oxidation product, eventually comprising 40–60% of the incorporated oxygen. Carboxylic acids and alcohols react to form esters and water, with vaporization of water driving the equilibrium toward ester forma...

The Photochemical Ozone Creation Potential (POCP) scale quantifies the relative abilities of volatile organic compounds (VOCs) to produce ground level ozone. POCP values are usually calculated using atmospheric boundary layer models containing detailed representations of atmospheric VOC degradation chemistry. The sensitivity of POCP values to variation of a number of kinetic and mechanistic parameters has been investigated here. It is shown that POCP values for VOCs can be rationalized in terms of their molecular structure and OH reactivity. As a result, a simple method has been developed and optimized that allows POCP values for north-west European and USA urban reference conditions to be estimated for alkanes, alkenes, aromatic hydrocarbons, and several oxygenated VOC classes without the requirement to construct a detailed chemical mechanism or run an atmospheric model. The procedure for determining the estimated POCP value (POCPE) is described, and the results are presented and discussed.

The North China Plain (NCP) frequently experiences heavy haze pollution, particularly during wintertime. In winter 2015–2016, the NCP region suffered several extremely severe haze episodes with air pollution red alerts issued in many cities. We have investigated the sources and aerosol evolution processes of the severe pollution episodes in Handan, a typical industrialized city in the NCP region, using real-time measurements from an intensive field campaign during the winter of 2015–2016. The average (±1σ) concentration of submicron aerosol (PM1) during 3 December 2015–5 February 2016 was 187.6 (±137.5) µg m−3, with the hourly maximum reaching 700.8 µg m−3. Organic was the most abundant component, on average accounting for 45 % of total PM1 mass, followed by sulfate (15 %), nitrate (14 %), ammonium (12 %), chloride (9 %) and black carbon (BC, 5 %). Positive matrix factorization (PMF) with the multilinear engine (ME-2) algorithm identified four major organic aerosol (OA) sources, including traffic emissions represented by a hydrocarbon-like OA (HOA, 7 % of total OA), industrial and residential burning of coal represented by a coal combustion OA (CCOA, 29 % of total OA), open and domestic combustion of wood and crop residuals represented by a biomass burning OA (BBOA, 25 % of total OA), and formation of secondary OA (SOA) in the atmosphere represented by an oxygenated OA (OOA, 39 % of total OA). Emissions of primary OA (POA), which together accounted for 61 % of total OA and 27 % of PM1, are a major cause of air pollution during the winter. Our analysis further uncovered that primary emissions from coal combustion and biomass burning together with secondary formation of sulfate (mainly from SO2 emitted by coal combustion) are important driving factors for haze evolution. However, the bulk composition of PM1 showed comparatively small variations between less polluted periods (daily PM2. 5 ≤ 75 µg m−3) and severely polluted periods (daily PM2. 5 > 75 µg m−3), indicating relatively synchronous increases of all aerosol species during haze formation. The case study of a severe haze episode, which lasted 8 days starting with a steady buildup of aerosol pollution followed by a persistently high level of PM1 (326.7–700.8 µg m−3), revealed the significant influence of stagnant meteorological conditions which acerbate air pollution in the Handan region. The haze episode ended with a shift of wind which brought in cleaner air masses from the northwest of Handan and gradually reduced PM1 concentration to −3 after 12 h. Aqueous-phase reactions under higher relative humidity (RH) were found to significantly promote the production of secondary inorganic species (especially sulfate) but showed little influence on SOA.

The carbon efficiency of bioenergy systems is of critical importance in discussions pertaining to biomass availability for the displacement of petroleum. Classical carbohydrate fermentations to make simple alcohols are carbon inefficient as they discard 1/3 of biomass holocellulose as CO2. Biomass' lignin is typically burned for heat and power instead of liquid fuel, discarding another sizeable fraction of the biomass carbon. Carbon is the backbone element in hydrocarbon fuels and these losses limit full utilization of the carbon captured by photosynthesis. The DOE Billion-ton Study Update optimistically projects enough biomass carbon to cover 2/3 of the estimated fuel usage in the transportation sector by 2030. Fast pyrolysis combined with electrocatalytic energy upgrading using renewable electricity offers a more carbon-retentive pathway for biomass to renewable fuels. This fast pyrolysis-based sequence offers the added benefit of fixing atmospheric carbon in the form of biochar, which provides a mechanism for long-term carbon storage. An associated challenge is that the liquid “bio-oil” from biomass fast pyrolysis contains functional groups like carboxylic acids, carbonyls, and oxygenated aromatics. Their presence hinders the storage and transportation of bio-oil. We propose a potential solution with localized electrocatalytic hydrogenation as an immediate measure to stabilize bio-oil via oxygen removal and carbonyl saturation. Electrocatalytically stabilized bio-oil can be stored and/or transported to centralized refineries for further upgrading. Compared to microbial bioconversion, the strategy proposed here enables significantly higher yields of renewable hydrocarbon fuels and offers a large-scale mechanism for chemical storage of renewable but intermittently generated electrical energy as transportation fuel.

Producing, transporting, and refining crude oil into fuels such as gasoline and diesel accounts for ∼15 to 40% of the “well-to-wheels” life-cycle greenhouse gas (GHG) emissions of transport fuels (1). Reducing emissions from petroleum production is of particular importance, as current transport fleets are almost entirely dependent on liquid petroleum products, and many uses of petroleum have limited prospects for near-term substitution (e.g., air travel). Better understanding of crude oil GHG emissions can help to quantify the benefits of alternative fuels and identify the most cost-effective opportunities for oil-sector emissions reductions (2). Yet, while regulations are beginning to address petroleum sector GHG emissions (3–5), and private investors are beginning to consider climate-related risk in oil investments (6), such efforts have generally struggled with methodological and data challenges. First, no single method exists for measuring the carbon intensity (CI) of oils. Second, there is a lack of comprehensive geographically rich datasets that would allow evaluation and monitoring of life-cycle emissions from oils. We have previously worked to address the first challenge by developing open-source oil-sector CI modeling tools [OPGEE (7, 8), supplementary materials (SM) 1.1]. Here, we address the second challenge by using these tools to model well-to-refinery CI of all major active oil fields globally—and to identify major drivers of these emissions.

From the earliest observations of ozone in the lower atmosphere in the 19th century, both measurement methods and the portion of the globe observed have evolved and changed. These methods have different uncertainties and biases, and the data records differ with respect to coverage (space and time), information content, and representativeness. In this study, various ozone measurement methods and ozone datasets are reviewed and selected for inclusion in the historical record of background ozone levels, based on relationship of the measurement technique to the modern UV absorption standard, absence of interfering pollutants, representativeness of the well-mixed boundary layer and expert judgement of their credibility. There are significant uncertainties with the 19th and early 20th-century measurements related to interference of other gases. Spectroscopic methods applied before 1960 have likely underestimated ozone by as much as 11% at the surface and by about 24% in the free troposphere, due to the use of differing ozone absorption coefficients. There is no unambiguous evidence in the measurement record back to 1896 that typical mid-latitude background surface ozone values were below about 20 nmol mol–1, but there is robust evidence for increases in the temperate and polar regions of the northern hemisphere of 30–70%, with large uncertainty, between the period of historic observations, 1896–1975, and the modern period (1990–2014). Independent historical observations from balloons and aircraft indicate similar changes in the free troposphere. Changes in the southern hemisphere are much less. Regional representativeness of the available observations remains a potential source of large errors, which are difficult to quantify. The great majority of validation and intercomparison studies of free tropospheric ozone measurement methods use ECC ozonesondes as reference. Compared to UV-absorption measurements they show a modest (~1–5% ±5%) high bias in the troposphere, but no evidence of a change with time. Umkehr, lidar, and FTIR methods all show modest low biases relative to ECCs, and so, using ECC sondes as a transfer standard, all appear to agree to within one standard deviation with the modern UV-absorption standard. Other sonde types show an increase of 5–20% in sensitivity to tropospheric ozone from 1970–1995. Biases and standard deviations of satellite retrieval comparisons are often 2–3 times larger than those of other free tropospheric measurements. The lack of information on temporal changes of bias for satellite measurements of tropospheric ozone is an area of concern for long-term trend studies.

Photochemical reactors were used to study the kinetics and mechanisms of reactions of Cl atoms and OH radicals with hexa- and penta-fluorobenzene (C6F6, C6F5H) in 700 Torr total pressure of N2, air, or O2 diluent at 296 ± 2 K. C6F6 and C6F5H undergo ring-opening following 254 nm UV irradiation, but with small quantum yields (φ < 0.03). Reaction of Cl atoms with C6F6 proceeds via adduct formation, while the reaction of Cl atoms with C6F5H proceeds via hydrogen abstraction and adduct formation. C6F6–Cl and C6F5H–Cl adducts decompose rapidly (k ∼ 105–106 s−1) reforming the reactants, and react with Cl atoms to form products. The fraction of adduct reacting with Cl atoms increases with steady state Cl atom concentration, resulting in an increasing apparent effective Cl atom rate constant. The rate constant for the H-abstraction channel for Cl + C6F5H is estimated at (7.3 ± 5.7) × 10−16 cm3 molecule−1 s−1. Establishment of the equilibrium between the adducts and the aromatic reactant + Cl occurs rapidly with equilibrium constants of K([adduct]/[aromatic][Cl]) = (1.96 ± 0.11) × 10−16 and (9.28 ± 0.11) × 10−17 cm3 molecule−1 for C6F6 and C6F5H, respectively. Reaction of the adducts with O2 occurs slowly with estimated rate constants of

The emergence of mass-produced aluminum sheet intensive vehicles presents an opportunity for recyclers to shift towards high value recycling into wrought alloys. We use dynamic material flow analyses (2015–2050) to estimate the timing, scale, and composition of U.S. aluminum automotive body sheet (ABS) scrap generated from the aluminum ABS intensive vehicles with the highest U.S. sales: Ford F-150, Super Duty, Expedition, and Lincoln Navigator. Lifespan distribution models are derived for each vehicle, and 5xxx and 6xxx series sheet alloys are aggregated according to their copper and magnesium content. A Markov chain model is used to estimate the fraction of deregistered vehicles scrapped domestically versus exported. It is found that the above four vehicles account for around 1,200 kt of aluminum ABS embedded within the 2020 U.S. fleet. The aluminum ABS intensive construction of these vehicles presents a unique opportunity to U.S. recyclers. If production continues at the current volumes, aluminum ABS scrap from these vehicles will increase to approximately 125 kt/year in 2035 and 246 kt/year in 2050. The majority of this scrap will be available for U.S. processing with

Smog chamber Fourier transform infrared techniques were used to investigate the kinetics of the reaction of CF 3 CF 2 OCH 3 with Cl atoms and OH radicals: k (Cl + CF 3 CF 2 OCH 3 ) = (1.09 ± 0.16) × 10 −13 and k (OH + CF 3 CF 2 OCH 3 ) = (1.28 ± 0.19) × 10 −14 cm 3 molecule −1 s −1 in 700 Torr total pressure of N 2 /O 2 at 296 ± 2 K. The Cl-initiated oxidation of CF 3 CF 2 OCH 3 gives CF 3 CF 2 OCHO in a yield indistinguishable from 100%. An estimate of k (Cl + CF 3 CF 2 OCHO) = (1.18 ± 0.34) × 10 −14 cm 3 molecule −1 s −1 is provided. Based on the OH reaction rate, the atmospheric lifetime of CF 3 CF 2 OCH 3 is estimated to be 5.0 years. The 100-year time horizon global warming potential of CF 3 CF 2 OCH 3 is estimated to be 585. The atmospheric impact of CF 3 CF 2 OCH 3 is discussed.

Summary Petroleum from unconventional reserves is making an increasingly important contribution to the transportation fuel supply, but is generally more expensive and has greater environmental burdens than petroleum from conventional sources. Life cycle assessments (LCAs) of alternative fuel-vehicle technologies typically consider conventional internal combustion engine vehicles fueled by gasoline produced from the average petroleum slate used in refineries as a baseline. Large-scale deployment of alternative fuel-vehicle technologies will decrease petroleum demand and lead to decreased production at the economic margin (unconventional oil), but this is not considered in most current LCAs. If marginal petroleum resources have larger impacts than average petroleum resources, the environmental benefits of petroleum demand reduction are underestimated by the current modeling approaches. Often, models include some consequential-based impacts (such as indirect land-use change for biofuels), but exclude others (such as avoided unconventional oil production). This approach is inconsistent and does not provide a robust basis for public policy and private investment strategy decisions. We provide an example to illustrate the potential scale of these impacts, but further research is needed to establish and quantify these marginal effects and incorporate them into LCAs of both conventional and alternative fuel-vehicle technologies.

The OH-initiated photo-oxidation of perfluoro ethyl vinyl ether (C2F5OCF[double bond, length as m-dash]CF2, PEVE) in air (298 K, 50 and 750 Torr total pressure) was studied in a photochemical reactor using in situ detection of PEVE and its products by Fourier transform IR absorption spectroscopy. The relative rate technique was used to derive the rate coefficient, k1, for the reaction of PEVE with OH as k1 = (2.8 ± 0.3) × 10−12 cm3 molecule−1 s−1. The photo-oxidation of PEVE in the presence of NOx at 1 bar results in formation of C2F5OCFO, FC(O)C(O)F and CF2O in molar yields of 0.50 ± 0.07, 0.46 ± 0.07 and 1.50 ± 0.22, respectively. FC(O)C(O)F and CF2O are formed partially in secondary, most likely heterogeneous processes. At a reduced pressure of 50 Torr, the product distribution is shifted towards formation of FC(O)C(O)F, indicating the important role of collisional quenching of initially formed association complexes, and enabling details of the reaction mechanism to be elucidated. An atmospheric photo-oxidation mechanism for PEVE is presented and the environmental implications of PEVE release and degradation are discussed.

A comprehensive component-level assessment of several strategic and minor metals (SaMMs), including copper, manganese, magnesium, nickel, tin, niobium, light rare earth elements (LREEs; lanthanum, cerium, praseodymium, neodymium, promethium, and samarium), cobalt, silver, tungsten, heavy rare earth elements (yttrium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium), and gold, use in the 2013 model year Ford Fiesta, Focus, Fusion, and F-150 is presented. Representative material contents in cars and light-duty trucks are estimated using comprehensive, component-level data reported by suppliers. Statistical methods are used to accommodate possible errors within the database and provide estimate bounds. Results indicate that there is a high degree of variability in SaMM use and that SaMMs are concentrated in electrical, drivetrain, and suspension subsystems. Results suggest that trucks contain greater amounts of aluminum, nickel, niobium, and silver and significantly greater amounts of magnesium, manganese, gold, and LREEs. We find tin and tungsten use in automobiles to be 3-5 times higher than reported by previous studies which have focused on automotive electronics. Automotive use of strategic and minor metals is substantial, with 2013 vehicle production in the United States, Canada, EU15, and Japan alone accounting for approximately 20% of global production of Mg and Ta and approximately 5% of Al, Cu, and Sn. The data and analysis provide researchers, recyclers, and decision-makers additional insight into the vehicle content of strategic and minor metals of current interest.

The use of oxygenated fuels decreases particulate matter (PM) emissions from diesel engines. Studies using engines, experimental flames, and modeling have shown that the decrease in soot emissions ...

Smog chambers with in situ FTIR detection were used to measure rate coefficients in 700 Torr of air and 296 ± 2 K of: k(Cl+(CF3)2CHOCH3) = (5.41 ± 1.63) × 10(-12), k(Cl+(CF3)2CHOCHO) = (9.44 ± 1.81) × 10(-15), k(Cl+CF3C(O)OCH3) = (6.28 ± 0.98) × 10(-14), k(OH+(CF3)2CHOCH3) = (1.86 ± 0.41) × 10(-13), and k(OH+(CF3)2CHOCHO) = (2.08 ± 0.63) × 10(-14) cm(3) molecule(-1) s(-1). The Cl atom initiated oxidation of (CF3)2CHOCH3 gives (CF3)2CHOCHO in a yield indistinguishable from 100%. The OH radical initiated oxidation of (CF3)2CHOCH3 gives the following products (molar yields): (CF3)2CHOCHO (76 ± 8)%, CF3C(O)OCH3 (16 ± 2)%, CF3C(O)CF3 (4 ± 1)%, and C(O)F2 (45 ± 5)%. The primary oxidation product (CF3)2CHOCHO reacts with Cl atoms to give secondary products (molar yields): CF3C(O)CF3 (67 ± 7)%, CF3C(O)OCHO (28 ± 3)%, and C(O)F2 (118 ± 12)%. CF3C(O)OCH3 reacts with Cl atoms to give: CF3C(O)OCHO (80 ± 8)% and C(O)F2 (6 ± 1)%. Atmospheric lifetimes of (CF3)2CHOCH3, (CF3)2CHOCHO, and CF3C(O)OCH3 were estimated to be 62 days, 1.5 years, and 220 days, respectively. The 100-year global warming potentials (GWPs) for (CF3)2CHOCH3, (CF3)2CHOCHO, and CF3C(O)OCH3 are estimated to be 6, 121, and 46, respectively. A comprehensive description of the atmospheric fate of (CF3)2CHOCH3 is presented.

FTIR smog chamber techniques were used to measure the rate coefficients k (Cl + cis -CF 3 CH CHCl) = (6.26 ± 0.84) × 10 –11 , k (OH + cis -CF 3 CH CHCl) = (8.45 ± 1.52) × 10 –13 , and k (O 3 + cis -CF 3 CH CHCl) = (1.53 ± 0.12) × 10 –21 cm 3 molecule –1 s –1 . The atmospheric lifetime of cis -CF 3 CH CHCl is determined by reaction with OH radicals and is estimated to be 14 days. The infrared spectrum of cis -CF 3 CH CHCl was recorded and the integrated absorption over the range 600–2000 cm −1 was measured to be (1.48 ± 0.07) × 10 –16 cm molecule −1 . Accounting for non-uniform horizontal and vertical mixing leads to a GWP 100 value of essentially zero. Correction to account for unwanted Cl atom chemistry in our previous relative rate study of the kinetics of the reaction of OH with trans -CF 3 CH CHCl gives k (OH + trans -CF 3 CH CHCl) = (3.61 ± 0.37) × 10 –13 cm 3 molecule –1 s –1 .

The atmospheric loss processes of N2O and CH4, their estimated uncertainties, lifetimes, and impacts on ozone abundance and long-term trends are examined using atmospheric model calculations and updated kinetic and photochemical parameters and uncertainty factors from Stratospheric Processes and their Role in Climate (SPARC) (2013). The uncertainty ranges in calculated N2O and CH4 global lifetimes computed using the SPARC estimated uncertainties are reduced by nearly a factor of 2 compared with uncertainties from Sander et al. (2011). Uncertainties in CH4 loss due to reaction with OH and O(D-1) have relatively small impacts on present-day global total ozone (0.2-0.5%). Uncertainty in the Cl+CH4 reaction affects the amount of chlorine in radical versus reservoir forms and has a modest impact on present-day southern hemisphere (SH) polar ozone (similar to 6%) and on the rate of past ozone decline and future recovery. Uncertainty in the total rate coefficient for the O(D-1)+N2O reaction results in a substantial range in present-day stratospheric odd nitrogen (20-25%) and global total ozone (1.5-2.5%). Uncertainty in the O(D-1)+N2O reaction branching ratio for the O-2+N-2 and 2NO product channels results in moderate impacts on odd nitrogen (+/- 10%) and global ozone (+/- 1%), with uncertainty in N2O photolysis resulting in relatively small impacts (+/- 5% in odd nitrogen, +/- 0.5% in global ozone). Uncertainties in the O(D-1)+N2O reaction and its branching ratio also affect the rate of past global total ozone decline and future recovery, with a range in future ozone projections of +/- 1-1.5% by 2100, relative to present day.

International audience; It is hard to overstate the importance of oxygenated organiccompounds in atmospheric chemistry. Oxygenated organiccompounds are emitted into the atmosphere from natural andman-made sources, and they are formed in the atmosphere asoxidation products of all hydrocarbons present in theatmosphere. Oxygenated volatile organic compounds(OVOCs) are generally more reactive than the alkanes fromwhich they are derived. OVOCs play an active role in thesequence of chemical reactions responsible for troposphericozone formation in both polluted and remote environments.

The oxidation of 2-butyl radicals (and to a lesser extent 1-butyl radicals) has been studied over the temperature range 298 K to 735 K. The reaction of Cl atoms (formed by 360 nm irradiation of Cl2) with n-butane generated the 2-butyl radicals in mixtures of n-C4H10, O2, and Cl2 at temperatures below 600 K. Above 600 K, 2-butyl radicals were produced by thermal combustion reactions in the absence of chlorine. The yields of the products were measured by gas chromatography using a flame ionization detector. Major products quantified include acetone, acetic acid, acetaldehyde, butanone, 2-butanol, butanal, 1- and 2- chlorobutane, 1-butene, trans-2-butene, and cis-2-butene. At 298 K, the major oxygenated products are those expected from bimolecular reactions of 2-butylperoxy radicals (butanone, 2-butanol, and acetaldehyde). As the temperature rises to 390 K, the butanone decreases while acetaldehyde increases because of the increased rate of 2-butoxy radical decomposition. Acetone and acetic acid first appear...

Direct emissions of N 2 O from global transportation (land, air, water) are estimated to be 0.142 ± 0.065 Tg N 2 O–N yr −1 in 2010 with the majority (≈55%) of emissions resulting as an unwanted by-product from catalytic emission control systems of light-duty vehicles. Emissions from global transportation accounted for 3 ± 1% of current estimates of the total anthropogenic emissions. With anticipated improvements in the emission control systems of light-duty vehicles, the emissions of N 2 O from global transportation are expected to decline to 0.108 ± 0.065 Tg N 2 O–N yr −1 by 2030 despite a substantial increase in global transportation activity.

China's oil imports and greenhouse gas (GHG) emissions have grown rapidly over the past decade. Addressing energy security and GHG emissions is a national priority. Replacing conventional vehicles with electric vehicles (EVs) offers a potential solution to both issues. While the reduction in petroleum use and hence the energy security benefits of switching to EVs are obvious, the GHG benefits are less obvious. We examine the current Chinese electric grid and its evolution and discuss the implications for EVs. China's electric grid will be dominated by coal for the next few decades. In 2015 in Beijing, Shanghai, and Guangzhou, EVs will need to use less than 14, 19, and 23 kWh/100 km, respectively, to match the 183 gCO2/km WTW emissions for energy saving vehicles. In 2020, in Beijing, Shanghai, and Guangzhou EVs will need to use less than 13, 18, and 20 kWh/100 km, respectively, to match the 137 gCO2/km WTW emissions for energy saving vehicles. EVs currently demonstrated in China use 24-32 kWh/100 km. Electrification will reduce petroleum imports; however, it will be very challenging for EVs to contribute to government targets for GHGs emissions reduction.

FTIR smog chamber techniques were used to measure k (Cl + (CF 3 ) 2 CFOCH 3 ) = (1.80 ± 0.42) × 10 –13 , k (Cl + (CF 3 ) 2 CFOCHO) = (1.47 ± 0.56) × 10 −14 , and k (OH + (CF 3 ) 2 CFOCH 3 ) = (1.55 ± 0.24) × 10 −14 cm 3 molecule −1 s −1 . The chlorine-atom initiated oxidation of (CF 3 ) 2 CFOCH 3 in air in the absence of NO X results in conversion of (CF 3 ) 2 CFOCH 3 into the formate, (CF 3 ) 2 CFOCHO, in a yield indistinguishable from 100%. In the presence of NO X , the (CF 3 ) 2 CFOCHO yield was decreased by approximately 17%, which we attribute to the formation of peroxy and/or alkoxy nitrates. The atmospheric lifetime of (CF 3 ) 2 CFOCH 3 was estimated to 3.7 years. The infrared spectrum of (CF 3 ) 2 CFOCH 3 was measured and a global warming potential GWP 100 = 354 was determined.

Remarkable progress has occurred over the last 100 years in our understanding of atmospheric chemical composition, stratospheric and tropospheric chemistry, urban air pollution, acid rain, and the formation of airborne particles from gas-phase chemistry. Much of this progress was associated with the developing understanding of the formation and role of ozone and of the oxides of nitrogen, NO and NO2, in the stratosphere and troposphere. The chemistry of the stratosphere, emerging from the pioneering work of Chapman in 1931, was followed by the discovery of catalytic ozone cycles, ozone destruction by chlorofluorocarbons, and the polar ozone holes, work honored by the 1995 Nobel Prize in Chemistry awarded to Crutzen, Rowland, and Molina. Foundations for the modern understanding of tropospheric chemistry were laid in the 1950s and 1960s, stimulated by the eye-stinging smog in Los Angeles. The importance of the hydroxyl (OH) radical and its relationship to the oxides of nitrogen (NO and NO2) emerged. The chemical processes leading to acid rain were elucidated. The atmosphere contains an immense number of gas-phase organic compounds, a result of emissions from plants and animals, natural and anthropogenic combustion processes, emissions from oceans, and from the atmospheric oxidation of organics emitted into the atmosphere. Organic atmospheric particulate matter arises largely as gas-phase organic compounds undergo oxidation to yield low-volatility products that condense into the particle phase. A hundred years ago, quantitative theories of chemical reaction rates were nonexistent. Today, comprehensive computer codes are available for performing detailed calculations of chemical reaction rates and mechanisms for atmospheric reactions. Understanding the future role of atmospheric chemistry in climate change and, in turn, the impact of climate change on atmospheric chemistry, will be critical to developing effective policies to protect the planet.

Engine-out and tailpipe emissions of NOx, CO, nonmethane hydrocarbons (NMHC), nonmethane organic gases (NMOG), total hydrocarbons (THC), methane, ethene, acetaldehyde, formaldehyde, ethanol, N2O, and NH3 from a 2006 model year Mercury Grand Marquis flexible fuel vehicle (FFV) operating on E0, E10, E20, E30, E40, E55, and E80 on a chassis dynamometer are reported. With increasing ethanol content in the fuel, the tailpipe emissions of ethanol, acetaldehyde, formaldehyde, methane, and ammonia increased; NOx and NMHC decreased; while CO, ethene, and N2O emissions were not discernibly affected. NMOG and THC emissions displayed a pronounced minimum with midlevel (E20-E40) ethanol blends; 25-35% lower than for E0 or E80. Emissions of NOx decreased by approximately 50% as the ethanol content increased from E0 to E30-E40, with no further decrease seen with E55 or E80. We demonstrate that emission trends from FFVs are explained by fuel chemistry and engine calibration effects. Fuel chemistry effects are fundamental in nature; the same trend of increased ethanol, acetaldehyde, formaldehyde, and CH4 emissions and decreased NMHC and benzene emissions are expected for all FFVs. Engine calibration effects are manufacturer and model specific; emission trends for NOx, THC, and NMOG will not be the same for all FFVs. Implications for air quality are discussed.

[1] Perfluorinated compounds impact the Earth's radiative balance. Perfluorotributylamine (PFTBA) belongs to the perfluoroalkyl amine class of compounds; these have not yet been investigated as long-lived greenhouse gases (LLGHGs). Atmospheric measurements of PFTBA made in Toronto, ON, detected a mixing ratio of 0.18 parts per trillion by volume. An instantaneous radiative efficiency of 0.86 W m−2 ppb−1 was calculated from its IR absorption spectra, and a lower limit of 500 years was estimated for its atmospheric lifetime. PFTBA has the highest radiative efficiency of any compound detected in the atmosphere. If the concentration in Toronto is representative of the change in global background concentration since the preindustrial period, then the radiative forcing of PFTBA is 1.5 × 10−4 W m−2. We calculate the global warming potential of PFTBA over a 100 year time horizon to be 7100. Detection of PFTBA demonstrates that perfluoroalkyl amines are a class of LLGHGs worthy of future study.

Polyfluorinated amides (PFAMs) are a class of fluorinated compounds which were produced as unintentional byproducts in the electrochemical fluorination process used for polyfluorinated sulfonamide synthesis in 1947-2002. To investigate the historical potential of PFAMs as an atmospheric perfluorinated acid (PFCA) source we studied N-ethylperfluorobutyramide (EtFBA) as a surrogate for longer chained PFAMs. Smog chamber relative rate techniques were used to measure bimolecular rate coefficients for reactions of EtFBA with chlorine atoms and hydroxyl radicals. It was found kCl = (2.08 ± 0.15) × 10(-11) cm(3) molecule(-1) s(-1) and kOH = (2.65 ± 0.50) × 10(-12) cm(3) molecule(-1) s(-1) and the atmospheric lifetime of EtFBA with respect to reaction with OH was estimated to be approximately 4.4 days. Offline sampling with both GC-MS and LC-MS/MS techniques was used to determine the products and hence a plausible pathway of atmospheric oxidation of EtFBA. Three primary oxidation products were observed by GC-MS, the N-dealkylation product C3F7C(O)NH2 and two carbonyl products, probably C3F7C(O)N(H)C(O)CH3 and C3F7C(O)N(H)CH2CHO. These primary products react further to give perfluorocarboxylic acids (PFCAs) as detected by LC-MS/MS, suggesting that eight carbon PFAMs were a historical source of PFCAs to remote regions, including the Canadian Arctic.

International audience; The atmospheric oxidation of benzyl alcohol has been investigated using smog chambers at ICARE, FORD, and EUPHORE. The rate coefficient for reaction with OH radicals was measured and an upper limit for the reaction with ozone was established; kOH = (2.8 ± 0.4) × 10-11 at 297 ± 3 K (averaged value including results from Harrison and Wells) and kO3 < 2 × 10-19 cm3 molecule-1 s-1 at 299 K. The products of the OH radical initiated oxidation of benzyl alcohol in the presence of NOX were studied. Benzaldehyde, originating from H-abstraction from the −CH2OH group, was identified using in situ FTIR spectroscopy, HPLC-UV/FID, and GC-PID and quantified in a yield of (24 ± 5) %. Ring retaining products originating from OH-addition to the aromatic ring such as o-hydroxybenzylalcohol and o-dihydroxybenzene as well as ring-cleavage products such as glyoxal were also identified and quantified with molar yields of (22 ± 2)%, (10 ± 3)%, and (2.7 ± 0.7)%, respectively. Formaldehyde was observed with a molar yield of (27 ± 10)%. The results are discussed with respect to previous studies and the atmospheric oxidation mechanism of benzyl alcohol.

Ethanol provides a significant contribution to road transportation fuel in the US, Brazil, and elsewhere. Renewable fuels regulations in the US and EU imply that ethanol use will continue to increase in the near future. The high octane rating of ethanol could be used in a mid-level ethanol blend to increase the minimum octane number (Research Octane Number, RON) of regular-grade gasoline. Higher RON would enable greater thermal efficiency in future engines through higher compression ratio (CR) and/or more aggressive turbocharging and downsizing, and in current engines on the road today through more aggressive spark timing under some driving conditions. Such an approach would differ from the current practice of blending ethanol into a gasoline blendstock formulated with lower octane rating such that the net octane rating of the resulting final blend is unchanged from historical levels. Developing scenarios of future ethanol availability, we estimate that large increases (4–7 points) in the RON of US gasoline are possible by blending in an additional 10–20%v ethanol above the 10% already present. Keeping the blendstock RON at 88 (which provides E10 with ∼92.5 RON), we estimate RON would be increased to 94.3 for E15 to as much as 98.6 for E30. Even further RON increases may be achievable assuming changes to the blendstock RON and/or hydrocarbon composition. For example, an increase in blendstock RON from 88 to 92 would increase the RON of E10 from 92.5 to 95.6, and would provide higher RON with additional ethanol content (e.g., RON of 97.1 for E15 to 100.6 for E30). Potential CR increases are estimated for the different estimates of future octane number, including the effect of increased evaporative cooling from ethanol in direct injection engines. For the ethanol and blendstock RON scenarios considered, CR increases were estimated to be on the order of 1–3 CR-units for port fuel injection engines as well as for direct injection engines in which the greater evaporative cooling of ethanol can be fully utilized. Impacts to the fuel refining and blending sector and transition considerations are discussed. While additional work is needed to quantify and optimize the costs and benefits for both the automotive and refining sectors and for consumers, it appears that substantial societal benefits may be associated with capitalizing on the inherent high octane rating of ethanol in future higher octane number ethanol–gasoline blends.

Although present in the atmosphere with a combined concentration approximately 100,000 times lower than carbon dioxide (i.e., the principal anthropogenic driver of climate change), halogenated organic compounds are responsible for a warming effect of approximately 10% to 15% of the total anthropogen

FTIR smog chamber techniques were used to measure k (Cl + CF 3 CH 2 OCH 3 ) = (2.28 ± 0.44) × 10 −11 and k (OH + CF 3 CH 2 OCH 3 ) = (4.9 ± 1.3) × 10 −13 cm 3 molecule −1 s −1 in 700 Torr total pressure of air at 296 ± 2 K. The atmospheric lifetime of CF 3 CH 2 OCH 3 is estimated at 25 days. Reaction of Cl atoms with CF 3 CH 2 OCH 3 proceeds 79 ± 4% at the CH 3 group and 22 ± 2% at the CH 2 group. Reaction with OH radicals proceeds 55 ± 5% at the CH 3 group yielding CF 3 CH 2 OCHO and 45 ± 5% at the CH 2 group yielding COF 2 and CH 3 OCHO as primary oxidation products. The infrared spectrum of CF 3 CH(O)OCH 3 was measured and a global warming potential GWP 100 = 8 was estimated. The atmospheric chemistry and environmental impact of CF 3 CH 2 OCH 3 is discussed in context of the use of hydrofluoroethers as CFC substitutes.

The atmospheric chemistry of two C(4)H(8)O(2) isomers (methyl propionate and ethyl acetate) was investigated. With relative rate techniques in 980 mbar of air at 293 K the following rate constants were determined: k(C(2)H(5)C(O)OCH(3) + Cl) = (1.57 ± 0.23) × 10(-11), k(C(2)H(5)C(O)OCH(3) + OH) = (9.25 ± 1.27) × 10(-13), k(CH(3)C(O)OC(2)H(5) + Cl) = (1.76 ± 0.22) × 10(-11), and k(CH(3)C(O)OC(2)H(5) + OH) = (1.54 ± 0.22) × 10(-12) cm(3) molecule(-1) s(-1). The chlorine atom initiated oxidation of methyl propionate in 930 mbar of N(2)/O(2) diluent (with, and without, NO(x)) gave methyl pyruvate, propionic acid, acetaldehyde, formic acid, and formaldehyde as products. In experiments conducted in N(2) diluent the formation of CH(3)CHClC(O)OCH(3) and CH(3)CCl(2)C(O)OCH(3) was observed. From the observed product yields we conclude that the branching ratios for reaction of chlorine atoms with the CH(3)-, -CH(2)-, and -OCH(3) groups are49 ± 9%, 42 ± 7%, and9 ± 2%, respectively. The chlorine atom initiated oxidation of ethyl acetate in N(2)/O(2) diluent gave acetic acid, acetic acid anhydride, acetic formic anhydride, formaldehyde, and, in the presence of NO(x), PAN. From the yield of these products we conclude that at least 41 ± 6% of the reaction of chlorine atoms with ethyl acetate occurs at the -CH(2)- group. The rate constants and branching ratios for reactions of OH radicals with methyl propionate and ethyl acetate were investigated theoretically using transition state theory. The stationary points along the oxidation pathways were optimized at the CCSD(T)/cc-pVTZ//BHandHLYP/aug-cc-pVTZ level of theory. The reaction of OH radicals with ethyl acetate was computed to occur essentially exclusively (∼99%) at the -CH(2)- group. In contrast, both methyl groups and the -CH(2)- group contribute appreciably in the reaction of OH with methyl propionate. Decomposition via the α-ester rearrangement (to give C(2)H(5)C(O)OH and a HCO radical) and reaction with O(2) (to give CH(3)CH(2)C(O)OC(O)H) are competing atmospheric fates of the alkoxy radical CH(3)CH(2)C(O)OCH(2)O. Chemical activation of CH(3)CH(2)C(O)OCH(2)O radicals formed in the reaction of the corresponding peroxy radical with NO favors the α-ester rearrangement.

Summary There is disagreement on whether the supply of lithium is adequate to support a future global fleet of electric vehicles. We report a comprehensive analysis of the global lithium resources and compare it to an assessment of global lithium demand from 2010 to 2100 that assumes rapid and widespread adoption of electric vehicles. Recent estimates of global lithium resources have reached very different conclusions. We compiled data on 103 deposits containing lithium, with an emphasis on the 32 deposits that have a lithium resource of more than 100,000 tonnes each. For each deposit, data were compiled on its location, geologic type, dimensions, and content of lithium as well as current status of production where appropriate. Lithium demand was estimated under the assumption of two different growth scenarios for electric vehicles and other current battery and nonbattery applications. The global lithium resource is estimated to be about 39 Mt (million tonnes), whereas the highest demand scenario does not exceed 20 Mt for the period 2010 to 2100. We conclude that even with a rapid and widespread adoption of electric vehicles powered by lithium-ion batteries, lithium resources are sufficient to support demand until at least the end of this century.

Perfluorinated carboxylic acids are widely distributed in the environment, including remote regions, but their sources are not well understood. Perfluoropropionic acid (PFPrA, CF(3)CF(2)C(O)OH) has been observed in rainwater but the observed amounts can not be explained by currently known degradation pathways. Smog chamber studies were performed to assess the potential of photolysis of perfluoro-2-methyl-3-pentanone (PFMP, CF(3)CF(2)C(O)CF(CF(3))(2)), a commonly used fire-fighting fluid, to contribute to the observed PFPrA loadings. The photolysis of PFMP gives CF(3)CF(2)C·(O) and ·CF(CF(3))(2) radicals. A small (0.6%) but discernible yield of PFPrA was observed in smog chamber experiments by liquid chromatography-mass spectrometry offline chamber samples. The Tropospheric Ultraviolet-Visible (TUV) model was used to estimate an atmospheric lifetime of PFMP with respect to photolysis of 4-14 days depending on latitude and time of year. PFMP can undergo hydrolysis to produce PFPrA and CF(3)CFHCF(3) (HFC-227ea) in a manner analogous to the Haloform reaction. The rate of hydrolysis was measured using (19)F NMR at two different pHs and was too slow to be of importance in the atmosphere. Hydration of PFMP to give a geminal diol was investigated computationally using density functional theory. It was determined that hydration is not an important environmental fate of PFMP. The atmospheric fate of PFMP seems to be direct photolysis which, under low NO(x) conditions, gives PFPrA in a small yield. PFMP degradation contributes to, but does not appear to be the major source of, PFPrA observed in rainwater.

The relative rate method was used to measure k (Cl + hexafluorocyclobutene) = (8.88 ± 0.69) × 10 −13 , k (Cl + octafluorocyclopentene) = (1.02 ± 0.11) × 10 −12 , k (Cl + hexafluoro-1,3-butadiene) = (7.28 ± 0.99) × 10 −11 , k (OH + hexafluorocyclobutene) = (8.6 ± 1.6) × 10 −14 , k (OH + octafluorocyclopentene) = (1.01 ± 0.16) × 10 −13 , and k (OH + hexafluoro-1,3-butadiene) = (9.64 ± 1.76) × 10 −12 cm 3 molecule −1 s −1 in 700 Torr N 2 , or air, diluent at 295 K. The atmospheric lifetimes of hexafluorocyclobutene, octafluorocyclopentene, and hexafluoro-1,3-butadiene were estimated to be 135, 104, and 1.1 days, respectively. The 100 year time horizon global warming potentials for hexafluorocyclobutene and octafluorocyclopentene are 42 and 28.