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In this short response, we engage with four generous and stimulating commentaries on our Planetary Social Thought(2021). We endorse Cecilia Åsberg's suggestion that the boundary between the environmental humanities and social sciences is dissolving – but also call for more inventive relations between these disciplines and the natural sciences. We discuss László Cseke's account of the rise of factory-farmed ‘broiler’ chickens as a reversal of many of the achievements of the Earth over the last half-billion years. We agree with Franklin Ginn's suggestion that vegetality is a crucial vector of planetary self-exploration and invention – and one that can give us clues as to what life might become on other worlds. We reflect on Simon Dalby's observations about the lack of reference to planetary governance in the book, suggesting that we need a way of thinking about the politics of the Earth that goes beyond conflict and agonism – in Åsberg's words, that we need to learn not just to survive but to thrive.

ABSTRACTEmissions levels from current gasoline spark-ignited engines are low, and emissions changes associated with the blending of ethanol into gasoline are small and difficult to quantify. Addition of ethanol, with a high blending octane number, allows a reduction in aromatics in market gasoline. Blending behavior of ethanol is nonlinear, altering the distillation curve, including the 50% temperature point, T50. Increase in gasoline direct injection (GDI) engine technology in the fleet challenges ability of older models based on port fuel injection (PFI) results to predict the overall air quality impact of ethanol blending. Five different models derived from data collected through U.S. Environmental Protection Agency Energy Policy Act (EPAct) programs were used to predict LA92 Phase 1 particulate matter (PM) emissions for summer regular (SR) E0 (gasoline with 0% ethanol by volume), E10 (gasoline with 10% ethanol) and E15 (gasoline with 15% ethanol). Substantial reductions of PM for E10 and E15 relative to E0 were predicted when aromatics were displaced by ethanol to maintain octane rating. SR E0 and E10 were also matched to linear combinations of EPAct fuels and results showed a 35% PM reduction for SR E10 relative to SR E0. For GDI vehicles the Coordinating Research Council (CRC) E-94-3 study found that E10 had 23% or 29% PM increase. However, CRC E-129 found an E10 PM reduction of 10% when one E0 fuel and its splash blended (SB) E10 were compared. Both CRC project E-129 SB data and fuel triplets selected from the EPAct study showed variation for E15 emissions, although E-129 suggests that E15 in GDI offers about a 25% reduction of PM with respect to E0. Overall, data suggest that ethanol blending offers a modest to a substantial reduction of cold-start PM mass if aromatic levels of the finished products are reduced in response to ethanol addition.Implications: Studies of exhaust emissions effects of ethanol blending with gasoline vary in conclusions. Blending properties are nonlinear. Modeling of real-world emissions effects must consider all fuel composition adjustments and property changes associated with ethanol addition. Aromatics are reduced in E10 or E15, compared with E0, and distillation changes. PFI-derived models show reductions in cold-start PM for expected average E10 versus E0 pump fuel, due to reduced aromatic content. Relative emissions effects from older technology (PFI) engines do not predict newer engine (GDI) results reliably, but recent GDI data show reduced cold-start PM when ethanol displaces aromatics.

Late Ordovician (c.445 Ma) glacial sandstones form important gas reservoirs in the Illizi Basin, SW Algeria. These reservoirs have a high degree of depositional and diagenetic complexity, such that understanding and predicting reservoir quality (RQ) presents a major challenge to their economic development. Porosity is typically 1–10%, but reaches up to 15% and permeability is typically <10−15m2(<1 mD), but locally reaches >10−13m2(>100 mD). The key questions addressed herein concern the development and distribution of this RQ variability, specifically why has good RQ been locally preserved?Primary depositional fabric exerts a strong control on RQ. Muddy sandstones are either highly compacted or pervasively cemented by quartz and microporous illite, and have very poor RQ. Only fine- to medium-grained, moderately well sorted, clean sandstones can contain good RQ, but texturally and mineralogically similar sandstones span a wide range of porosity and permeability. This range is primarily driven by the degree of quartz cementation, with incomplete cementation resulting in the best RQ. Quartz overgrowths in incompletely cemented clean sandstones are patchy and non-luminescent in scanning electron microscopy with cathodoluminescence (SEM-CL), possibly indicating slow growth rates. There is tentative evidence to link incomplete quartz cementation with oil charging of the reservoir. An alternative or additional explanation of RQ preservation may be related to limited silica supply in the centres of the thickest, stacked, clean sandstones, where the better RQ tends to reside.The results of this study imply that sustained high-energy depositional processes, coupled with an early oil charge, are prerequisites for retaining the best RQ. This has important implications for the exploration and development of Late Ordovician glacial sandstones in the Illizi Basin, and potentially similar plays elsewhere.

ABSTRACTToday’s heavy-duty natural gas–fueled fleet is estimated to represent less than 2% of the total fleet. However, over the next couple of decades, predictions are that the percentage could grow to represent as much as 50%. Although fueling switching to natural gas could provide a climate benefit relative to diesel fuel, the potential for emissions of methane (a potent greenhouse gas) from natural gas–fueled vehicles has been identified as a concern. Since today’s heavy-duty natural gas–fueled fleet penetration is low, today’s total fleet-wide emissions will be also be low regardless of per vehicle emissions. However, predicted growth could result in a significant quantity of methane emissions. To evaluate this potential and identify effective options for minimizing emissions, future growth scenarios of heavy-duty natural gas–fueled vehicles, and compressed natural gas and liquefied natural gas fueling stations that serve them, have been developed for 2035, when the populations could be significant. The scenarios rely on the most recent measurement campaign of the latest manufactured technology, equipment, and vehicles reported in a companion paper as well as projections of technology and practice advances. These “pump-to-wheels”(PTW) projections do not include methane emissions outside of the bounds of the vehicles and fuel stations themselves and should not be confused with a complete wells-to-wheels analysis. Stasis, high, medium, and low scenario PTW emissions projections for 2035 were 1.32%, 0.67%, 0.33%, and 0.15% of the fuel used. The scenarios highlight that a large emissions reductions could be realized with closed crankcase operation, improved best practices, and implementation of vent mitigation technologies. Recognition of the potential pathways for emissions reductions could further enhance the heavy-duty transportation sectors ability to reduce carbon emissions.Implications: Newly collected pump-to-wheels methane emissions data for current natural gas technologies were combined with future market growth scenarios, estimated technology advancements, and best practices to examine the climate benefit of future fuel switching. The analysis indicates the necessary targets of efficiency, methane emissions, market penetration, and best practices necessary to enable a pathway for natural gas to reduce the carbon intensity of the heavy-duty transportation sector.

Conflicts in resource use between humans and wildlife populations are increasingly determined through quantitative approaches. To better understand interactions between birds and human activities in the marine environment, telemetry is routinely used to characterize the area use of species, but evaluations are often based on a small number of individuals taken as representative of a local population studied. Furthermore, the relative importance of the number of animals required and for what duration they should be tracked has received little attention. We examined the central‐place foraging movements of 24 lesser black‐backed gulls (Larus fuscus) from a protected population from 1 March to 31 August during 2010–2013. Using bootstrapping and non‐linear modeling, we investigated whether sample sizes were sufficient to characterize offshore area use by considering the cumulative area use for an increasing number of birds and duration of tracking. Box‐and‐whisker analysis suggested a minimum of 13 birds and a precautionary upper maximum of 41 birds were needed to describe 95% of the estimated area use of the population (defined by 100% occupancy). Tracking fewer birds for longer was more important than tracking more birds for less time. A period of 145 days was required to characterize area use for 13–41 birds; however, offshore areas were used primarily after May, meaning that a 97‐day tracking period from May onwards was also representative. Predicted and observed areas were strongly correlated, and the predicted area of 15 birds for 151 days was 91% of the total estimated for the population. These findings suggest that the data were suitable for determining interaction with offshore developments, and were characteristic of the population. This study has revealed the power of a long‐term tracking dataset, and has uncovered further complexities surrounding study design and analysis that may shape conclusions drawn. The method and considerations raised have wider applicability for other datasets where human‐wildlife resource use conflicts need to be assessed. © 2017 The Wildlife Society. Using a bootstrap resampling procedure, we found that a suitable number of individual lesser black‐backed gulls had been tracked from a study colony over a long enough time period to appropriately characterize area use of the population during breeding; therefore, confidence could be placed in further use of the data to assess interactions with offshore wind farms. We uncovered complexities surrounding study design and analysis that may shape conclusions drawn, but the techniques employed are widely applicable to assess the power of other tracking datasets.

While affirming their more-than-human concerns, Ruddick ((2017) Rethinking the subject, reimagining worlds. Dialogues in Human Geography(this issue).) proposes that there are limits to the capacity of relational ontologies to deal with the conflicting demands and extensive temporalities of the Anthropocene crisis. This commentary probes her alternative notions of a forcefulness and generativity that exceeds individuated bodies and of a semiosis that inheres in the workings of ecological and Earth systems.

This article explores the growing interface between climate-induced mobilities and participation in ‘global care chains’ under conditions in which climate change is already impacting on lives and livelihoods – especially in the Global South. The authors reconsider discourses on ‘climate migration’ in the light of everyday caring practices and adaptive responses to climate stress, evaluating how climate policy interferes with ‘grassroots’ flows of care. Early engagements tended towards alarmist predictions of mass climate-induced displacement, triggering proposals to ‘secure’ potential host nations against anticipated influxes. Recently, apparently more sober approaches have emerged, promoting labour migration as contributing positively to climate ‘resilience’. These new approaches encourage more able and resourceful people from under-resourced, climate-vulnerable regions to join trans-local or transnational labour markets – which often equates with predominantly female care workers entering global care chains. Effectively, this means that those best equipped to provide care in places where it is most urgently needed end up providing care in relatively privileged, less climate-vulnerable places. Questioning the climate justice implications of this mobilization against the gradient of vulnerability, the authors offer suggestions about how climate policy could actually support caring practices in the places where ordinary people struggle at the sharp edge of climate change.

This is a reply to:Conway, Philip. 2016. “Back down to Earth: reassembling Latour’s Anthropocenic geopolitics.” Global Discourse6 (1–2): 43–71. http://dx.doi.org/10.1080/23269995.2015.1004247

The effects of combustion feature prominently in the planetary predicament signaled by the Anthropocene thesis. Historical studies of pyrotechnology—the application of heat to transform earth materials—suggest a wide-ranging inquiry into human fire use might bring new insights to the practical and political challenges of the Anthropocene. Drawing on Deleuze and Guattari, I use the term pyrotechnic phylumto refer to the multimillennial developments of metallurgy, ceramics, and related “fiery arts” centered on the enclosed fire of the oven, kiln, and furnace. As an engagement with the forces and properties of the Earth, pyrotechnical innovation has a pronounced experimental and playful dimension—opening up possibilities that human geological agency might have aesthetic origins. Pyrotechnic histories also highlight the widely distributed character of innovation, raising questions about a singular thermo-industrial revolution centered on Europe. Bringing together a feeling for the creative, world-shaping aspects of the pyrotechnic arts and a sense of the decentered, collaborative nature of their development, it is suggested that the pyrotechnic phylum might be seen as a kind of a shared platform for political action. Although attentive to its current contraction and marginalization, I speculate about the possible role of pyrotechnology in a political aesthetics for the Anthropocene.

Tracking devices are useful in studying the movement and behaviour of birds throughout the year. However, the effects of device attachment must be monitored for bird welfare and the scientific veracity of information gathered. We report on a trial of three different harness types (leg-loop, body and wing) for attaching GPS devices to Lesser Black-backed Gulls Larus fuscusand of a leg-loop harness on Great Skuas Stercorarius skua. This trial evaluated the functionality of the device whilst deployed, harness retention and the effects of each harness on the birds. The leg-loop harness prevented the devices from charging, due to feathers overlapping their solar panels, and individuals of both species shed this attachment during the first breeding season. For Lesser Black-backed Gull, devices functioned properly when attached using body and wing harnesses; foraging behaviour and territory attendance of birds were similar to the findings of other studies. Despite small sample sizes, annual adult survival rates for Lesser Black-backed Gull were similar to published estimates, suggesting harnesses had no deleterious effects. The wing harness has a smaller amount of skin contact than the body harness, and a non-constricting fit that better accommodates changes in body size. The wing harness was therefore considered the most appropriate for long-term studies.

This commentary argues that one of the strengths of Dixon et al.'s (2012) paper is the way that it pushes a concern with inhuman entities and processes far beyond any entanglement with human lives. This takes us on a turn – strangely rare in human geography – from life or vitalityinto the realms of minerality. It is suggested that what makes this possible is the authors' refreshing willingness to explore aesthetic and ontological questions without feeling obliged to immediately demonstrate the political valence of these explorations.

West Virginia University, under contract to the Federal Transit Administration, has developed two tools to evaluate the pollutant emissions, green-house gases, and fuel economy of transit buses: a searchable database of transit vehicle emission data and a transit fleet emission inventory model. These tools, complemented by a transit vehicle life-cycle cost model developed by West Virginia University, Battelle, and Transit Resource Center for the Transportation Research Board, provide an interactive, approachable, and reliable method for users, primarily transit agencies, to evaluate overall fleet emissions and fuel consumption for optimization of fleet configuration and operation. These tools will be made available through an online website called the Integrated Bus Information System (IBIS). This paper describes development of the transit fleet inventory model and comparison with the U.S. Environmental Protection Agency (EPA) MOBILE6 and MOVES (motor vehicle emission simulator) emission inventory models. The IBIS model was developed from extensive chassis dynamometer data from several reference vehicles. Polynomial models were built through linear regression. These backbone models characterized the effects of driving activity on vehicle emissions and fuel consumption. Comparison of predicted emissions showed good agreement for hydrocarbon, carbon monoxide, and oxides of nitrogen emissions and acceptable agreement for particulate matter emissions. The EPA MOBILE6 model assumed constant values as a function of duty cycle for carbon dioxide emissions and fuel economy. The West Virginia University IBIS model and EPA MOVES model displayed similar trends for carbon dioxide emissions, but MOVES predicted substantially lower carbon dioxide levels.

Hybrid buses offer the potential for fuel savings for transit operators and are expected to become important components of bus fleets around the world in the coming decade. This paper describes how a spreadsheet tool for a life-cycle cost (LCC) model for transit buses was developed to assist transit agencies in forecasting life-cycle operating and capital costs when choosing among various bus technologies, including hybrids. The tool is a key deliverable in a project sponsored by TCRP to assess hybrid electric bus performance in real-world operation. Forty hybrid electric buses were evaluated at four U.S. transit agencies, along with comparable conventional diesel and compressed natural gas buses. The LCC tool was created to cover key capital- and operating-cost factors that are based on the real-world data collected. The model is extremely flexible, and the user can override nearly all the data so that the model can be used in the future as costs and technologies change. This paper focuses on the model's structure, describes the case study buses, and illustrates an example of LCC calculation by using the model. More information about the project and its other results and deliverables can be found in TCRP Report 132.

Hybrid buses offer the potential for fuel savings for transit operators and are expected to become important components of bus fleets around the world in the coming decade. This paper describes how a spreadsheet tool for a life-cycle cost (LCC) model for transit buses was developed to assist transit agencies in forecasting life-cycle operating and capital costs when choosing among various bus technologies, including hybrids. The tool is a key deliverable in a project sponsored by TCRP to assess hybrid electric bus performance in real-world operation. Forty hybrid electric buses were evaluated at four U.S. transit agencies, along with comparable conventional diesel and compressed natural gas buses. The LCC tool was created to cover key capital- and operating-cost factors that are based on the real-world data collected. The model is extremely flexible, and the user can override nearly all the data so that the model can be used in the future as costs and technologies change. This paper focuses on the model's structure, describes the case study buses, and illustrates an example of LCC calculation by using the model. More information about the project and its other results and deliverables can be found in TCRP Report 132.

West Virginia University, under contract to the Federal Transit Administration, has developed two tools to evaluate the pollutant emissions, greenhouse gases, and fuel economy of transit buses: a searchable database of transit vehicle emission data and a transit fleet emission inventory model. These tools, complemented by a transit vehicle life-cycle cost model developed by West Virginia University, Battelle, and Transit Resource Center for the Transportation Research Board, provide an interactive, approachable, and reliable method for users, primarily transit agencies, to evaluate overall fleet emissions and fuel consumption for optimization of fleet configuration and operation. These tools will be made available through an online website called the Integrated Bus Information System (IBIS). This paper describes development of the transit fleet inventory model and comparison with the U.S. Environmental Protection Agency (EPA) MOBILE6 and MOVES (motor vehicle emission simulator) emission inventory models. The IBIS model was developed from extensive chassis dynamometer data from several reference vehicles. Polynomial models were built through linear regression. These backbone models characterized the effects of driving activity on vehicle emissions and fuel consumption. Comparison of predicted emissions showed good agreement for hydrocarbon, carbon monoxide, and oxides of nitrogen emissions and acceptable agreement for particulate matter emissions. The EPA MOBILE6 model assumed constant values as a function of duty cycle for carbon dioxide emissions and fuel economy. The West Virginia University IBIS model and EPA MOVES model displayed similar trends for carbon dioxide emissions, but MOVES predicted substantially lower carbon dioxide levels.

It is already well understood that unbinding materials and energy from their lithic reservoirs impacts upon Earth systems. But that is just the first stage of a cycle of ‘Anthropocene trouble’. This paper tracks the multiple ways in which subsequent Earth system change reacts back upon the social infrastructures of subsurface exploitation and the landscapes they produce. Shifting fire regimes, intensifying hydrometeorological events and sea level rise impact upon the infrastructures of hydrocarbon extraction, hydroclimatic change impacts upon infrastructures and landscapes of mineral extraction, and both pyroclimatic and hydroclimatic change impact upon nuclear infrastructures and on landscapes already contaminated by radioactive materials. To make sense of these ‘negative synergies’ we draw upon social science diagnoses of late modern hazards as well Anthropocene science’s deepening collaboration between ‘hard rock’ geology and Earth system science.

The population of the rufa subspecies of the Red Knot (Calidris canutus), which breeds in the central Canadian Arctic and mainly winters in Tierra del Fuego, has declined dramatically over the past 20 yr. Previously estimated at 100,000-150,000, the population now numbers 18,000-33,000 (18,000 if just the Tierra del Fuego birds are C. c. rufa, more if the Red Knots of uncertain subspecific status that winter in northern Brazil (7,500) or Florida (7,500) are also C. c. rufa). Counts show that the main Tierra del Fuego wintering population dropped from 67,546 in 1985 to 51,255 in 2000, 29,271 in 2002, 31,568 in 2004, but only 17,653 in 2005 and 17,211 in 2006. Demographic studies covering 1994-2002 showed that the population decline over that period was related to a drop in annual adult survival from 85% during 1994-1998 to 56% during 1999-2001. Population models showed that if adult survival remained low, C. c. rufa would go extinct within about 10 yr. After 2002, the population held up in 2003-2004, but plunged again by nearly 50% in 2005 increasing the likelihood of extinction within the next decade. Despite intensive studies, the reasons for the population decline and reduced adult survival are imperfectly known. During northward migration, most C. c. rufa stopover in Delaware Bay where they feed mainly on the eggs of horseshoe crabs (Limulus polyphemus) and lay down fat and protein reserves both to fuel the 3,000 km flight to the arctic breeding grounds and ensure their survival after they arrive at a time when food availability is often low. The crucial importance of Delaware Bay is demonstrated by studies that show that Red Knots with lower mass in Delaware Bay have lower survival than heavier birds and that from 1998-2002 the proportion of birds there at the end of May weighing more than the estimated departure mass of 180 g declined by >60%. This might be the result of the progressive failure of the food supply in Delaware Bay and/or a trend for birds to arrive there later and/or in poorer condition. In years when Red Knots experience reduced food availability and arrive late, the result may be an exacerbation of the effects of each of these deleterious factors. The main identified threat to the C. c. rufa population is the reduced availability of horseshoe crabs eggs in Delaware Bay arising from elevated harvest of adult crabs for bait in the conch and eel fishing industries. Since 1990 the crab population has declined substantially. Although significant uncertainty regarding the extent of the decline of the horseshoe crab population remains, there is general agreement that horseshoe crab stocks have declined to a level where increased management of the fishery is necessary and appropriate. The decline in crabs has led to a decrease in the density of eggs available to shorebirds. Because of the crab's delayed maturity, demographic models indicate that even if further exploitation of crabs ceases immediately, it will be some years before the horseshoe crab population recovers to its former level. Although clear evidence, as in 2003 and 2005, shows that the reduced availability of eggs is already having an impact in some years on the Red Knots ability to gain mass in Delaware Bay, it is likely that other threats to C. c. rufa exist and that these are the cause of some birds arriving in the bay late and/or in poor condition. It is not known what these are, but they could be related to Bahia Lomas, the main wintering site in Tierra del Fuego (because the largest reduction in recent years has occurred there and because northward migration from Bahia Lomas along the Atlantic coast of Argentina has taken place 1-2 wk later since year 2000). If it is proved that something leads Red Knots to arrive late in Delaware Bay and/or in poor condition, this does not diminish the importance of the Delaware Bay food resource.… [ABSTRACT FROM AUTHOR]

How should we respond to the increasingly dense bundle of economic, cultural and ecological interconnections that span the globe and stretch into the future? What kinds of ethical and public engagements are demanded of researchers who work on global environmental, economic and social issues? The term interdependencemay provide a powerful framework for advancing thinking and debate both within academia and among wider publics in relation to these questions. Members of the Open University's Geography Department have been working with partners to build the Interdependence Day project. The project combines research, cultural work, communications and public participation in an attempt to make sense of our responsibilities to people distant in space and time, and to the nonhuman natural world. This article reviews nearly a century of deployments of the term interdependencein political and academic writing, introduces the distinctive work that might be done with the term in the critical social sciences, and outlines the Interdependence Day project.

The West Virginia University Transportable Heavy-Duty Emissions Testing Laboratory was used to evaluate exhaust emissions from nine transit buses from six separate manufacturers, as commissioned by the Mexico City, Mexico, Secretariat of the Environment. The vehicles included a hybrid-drive diesel bus, two buses with lean-burn spark-ignited compressed natural gas (CNG) engines, and six buses powered by conventional diesel engines. Vehicle testing weights (curb weight plus passenger weight) ranged from 26,996 Ib (12,256 kg) to 57,025 Ib (25,889 kg), and passenger capacities ranged from 85 to 161. Two driving cycles, the European Transient Cycle (ETC, also known as the FIGE transient cycle) and a new, three-mode Mexico City Schedule, were used to simulate in-use driving conditions during emissions measurements. Diesel fuels with three different sulfur concentrations (15, 150, and 350 ppm) were also examined, and the lowest-sulfur fuel (15 ppm) was not found to have an appreciable direct effect on emissions. When the ETC was used, oxides of nitrogen (NOx) emissions varied from 5.5 to 11.6 g/mi, whereas particulate matter emissions varied from 0.02 to 0.86 g/mi. Significant differences in emissions and fuel economy for the two CNG buses raised the issue that fuel delivery systems must be optimized for operation at high altitudes. The differences in fuel economy and NOx emissions from the hybrid bus for congested and noncongested driving conditions were significantly less than those from the conventional diesel and CNG buses.

The West Virginia University Transportable Heavy-Duty Emissions Testing Laboratory was used to evaluate exhaust emissions from nine transit buses from six separate manufacturers, as commissioned by the Mexico City, Mexico, Secretariat of the Environment. The vehicles included a hybrid-drive diesel bus, two buses with lean-burn spark-ignited compressed natural gas (CNG) engines, and six buses powered by conventional diesel engines. Vehicle testing weights (curb weight plus passenger weight) ranged from 26,996 lb (12,256 kg) to 57,025 lb (25,889 kg), and passenger capacities ranged from 85 to 161. Two driving cycles, the European Transient Cycle (ETC, also known as the FIGE transient cycle) and a new, three-mode Mexico City Schedule, were used to simulate in-use driving conditions during emissions measurements. Diesel fuels with three different sulfur concentrations (15, 150, and 350 ppm) were also examined, and the lowest-sulfur fuel (15 ppm) was not found to have an appreciable direct effect on emissions. When the ETC was used, oxides of nitrogen (NOx) emissions varied from 5.5 to 11.6 g/mi, whereas particulate matter emissions varied from 0.02 to 0.86 g/mi. Significant differences in emissions and fuel economy for the two CNG buses raised the issue that fuel delivery systems must be optimized for operation at high altitudes. The differences in fuel economy and NOx emissions from the hybrid bus for congested and noncongested driving conditions were significantly less than those from the conventional diesel and CNG buses.

Particulate matter from diesel exhaust (DPM) is a pollutant of increasing concern, but its concentrations are difficult to measure in the environment. There are no unique chemical characteristics for DPM, so elemental carbon (EC) and black carbon (BC) measurements have historically been used to estimate its concentrations. However, both methods have limitations, and neither is capable of identifying specific sources. That results in significant uncertainties in the inferred DPM concentrations. In this study an intentional fuel-based tracer, iridium, was used to mark the DPM from a school bus's exhaust. Emissions tests established the mass ratio of DPM-iridium in the exhaust. Iridium measurements inside the bus during normal operations could then be used to calculate DPM concentrations without the limitations of methods relying on nonspecific markers. Previous studies have attributed in-bus concentrations of more than 30 μ/m3to the bus's exhaust, but they relied on nonspecific methods with a sensitivity of approximately 0.1 μ/m3. In this study the average measured DPMSBconcentration was 0.22 μ/m3—about 1% of previous estimates. Measurement sensitivity was approximately 0.001 μ/m3—100 times better than that of other methods. The sensitivity and specificity achieved show that this tracer method can resolve major ambiguities and uncertainties in estimates of actual DPM concentrations. The ability to estimate accurately the contributions of different sources to DPM concentrations provides a needed tool to evaluate proposed emission reduction strategies reliably.

Particulate matter from diesel exhaust (DPM) is a pollutant of increasing concern, but its concentrations are difficult to measure in the environment. There are no unique chemical characteristics for DPM, so elemental carbon (EC) and black carbon (BC) measurements have historically been used to estimate its concentrations. However, both methods have limitations, and neither is capable of identifying specific sources. That results in significant uncertainties in the inferred DPM concentrations. In this study an intentional fuel-based tracer, iridium, was used to mark the DPM from a school bus's exhaust. Emissions tests established the mass ratio of DPM-iridium in the exhaust. Iridium measurements inside the bus during normal operations could then be used to calculate DPM concentrations without the limitations of methods relying on nonspecific markers. Previous studies have attributed in-bus concentrations of more than 30 μ/m3 to the bus's exhaust, but they relied on nonspecific methods with a sensitivity of approximately 0.1 μ/m3. In this study the average measured DPMSB concentration was 0.22 μ/m3—about 1% of previous estimates. Measurement sensitivity was approximately 0.001 μ/m3—100 times better than that of other methods. The sensitivity and specificity achieved show that this tracer method can resolve major ambiguities and uncertainties in estimates of actual DPM concentrations. The ability to estimate accurately the contributions of different sources to DPM concentrations provides a needed tool to evaluate proposed emission reduction strategies reliably.

A new procedure for estimating the emissions of heavy-duty vehicles (HDVs) is presented. This procedure combines second-by-second data on actual in-use speed and acceleration of HDVs with data on average emissions rates of HDVs operating at corresponding speeds and acceleration rates. The initial implementation of this procedure used a limited amount of newly collected emissions data and a somewhat larger amount of previously collected HDV activity data. Validation tests provide a reasonable level of confidence about the validity of the nitrogen oxide (NOx) emissions factors produced using this initial implementation. However, these tests also indicate that the small amount of emissions data used in the initial implementation is insufficient to produce meaningful estimates of emissions factors for carbon monoxide or particulate matter. The research, the procedure that was developed, the validation tests, the results for NOxemissions, and NOxspeed correction factors derived from these results are briefly described. The speed correction factors are of particular interest. The minimum values for these factors occur at speeds higher than those currently used by the U.S. Environmental Protection Agency, and the factors grow more slowly at higher speeds than do the factors generated by MOBILE.

A new procedure for estimating the emissions of heavy-duty vehicles (HDVs) is presented. This procedure combines second-by-second data on actual in-use speed and acceleration of HDVs with data on average emissions rates of HDVs operating at corresponding speeds and acceleration rates. The initial implementation of this procedure used a limited amount of newly collected emissions data and a somewhat larger amount of previously collected HDV activity data. Validation tests provide a reasonable level of confidence about the validity of the nitrogen oxide (NOx) emissions factors produced using this initial implementation. However, these tests also indicate that the small amount of emissions data used in the initial implementation is insufficient to produce meaningful estimates of emissions factors for carbon monoxide or particulate matter. The research, the procedure that was developed, the validation tests, the results for NOx emissions, and NOx speed correction factors derived from these results are briefly described. The speed correction factors are of particular interest. The minimum values for these factors occur at speeds higher than those currently used by the U.S. Environmental Protection Agency, and the factors grow more slowly at higher speeds than do the factors generated by MOBILE.

Results from a study directed towards identifying and measuring the mutagenicity of diesel exhaust particulate matter involved in mining exposures, especially those which may synergistically affect genotoxic hazard, are presented in this paper. Particulate matter emissions from a diesel engine, representative of the ones found in underground mines, were sampled and assayed to determine the genotoxic potential as a function of engine operating conditions. Diesel exhaust was diluted in a multi-tube mini-dilution tunnel and the particulate matter was collected on 70 mm fluorocarbon coated glass fiber filters as well as on 8” × 10” hi-volume filters. A six node steady state duty cycle was used to relate engine operating conditions to the mutagenicity potential.Protocols developed for using a primary component of pulmonary surfactant as a medium for collecting and applying respirable particulate material to cells for mutagenicity testing offer a true representation of in-vivo delivery of such respired aerosols to pulmonary cells and the genetic material within. The surfactant dispersion technique is discussed in this paper. Methods have been developed to sample and assay the diesel soot and diesel soot/mineral dust complexes which would not compromise the surface and physical properties of the particulate material.

Particle shape has a profound influence on the behavior of the particles present in powders, controlling the manner in which they react, segregate, flow, and agglomerate. The currently available technique of Fourier transformation to characterize particle shape is cumbersome and can be used only by a skilled operator. Recently developed, the Sieve Cascadograph is able to characterize the shape of particles in the 0.1 to 1.0 mm size range. Employing the principle that the residence time of a particle on a sieve is a function of the particle shape, the Cascadograph consists of a stack of sieves of identical size in a shaking device. An essentially monosize powder sample (closely sized on a regular sieve stack) of about 2 grams is placed in the topmost sieve, and shaking commenced. The weight of powder leaving the lowest sieve is measured as a function of time, and is used to produce a signature representative of the particle shape distribution in the powder sample. Theoretical analysis demonstrates that monosize, monoshape samples leave the lowest sieve at a rate given by the gamma function with respect to time. Preliminary experimental results prove that the Cascadograph results are reproducible, and that a 20-sieve Cascadograph has high resolving power.