Improving Source Apportionment of Fine Particles in the Eastern United States Utilizing Temperature-Resolved Carbon Fractions

Abstract

The objectives of this study were to examine the use of carbon fractions to identify particulate matter (PM) sources, especially traffic‐related carbonaceous particle sources, and to estimate their contributions to the particle mass concentrations. In recent studies, positive matrix factorization (PMF) was applied to ambient fine PM (PM_2.5) compositional data sets of 24‐hr integrated samples including eight individual carbon fractions collected at three monitoring sites in the eastern United States: Atlanta, GA, Washington, DC, and Brigantine, NJ. Particulate carbon was analyzed using the Interagency Monitoring of Protected Visual Environments/Thermal Optical Reflectance method that divides carbon into four organic carbons (OC): pyrolized OC and three elemental carbon (EC) fractions. In contrast to earlier PMF studies that included only the total OC and EC concentrations, gasoline emissions could be distinguished from diesel emissions based on the differences in the abundances of the carbon fractions between the two sources. The compositional profiles for these two major source types show similarities among the three sites. Temperature‐resolved carbon fractions also enhanced separations of carbon‐rich secondary sulfate aerosols. Potential source contribution function analyses show the potential source areas and pathways of sulfate‐rich secondary aerosols, especially the regional influences of the biogenic, as well as anthropogenic secondary aerosol. This study indicates that temperature‐resolved carbon fractions can be used to enhance the source apportionment of ambient PM_2.5.     

Persistent organochlorine contaminants in hair samples of Northern Poland population, 1968-2009

The European regulation on chemicals, REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals), came into force on 1 June 2007. With pre-registration complete in 2008, data for these substances may provide an overview of the expected chemical space and its characteristics. In this paper, using various in silico computation tools, we evaluate 48 782 neutral organic compounds from the list to identify hazardous and safe compounds. Two different classification schemes (modified Verhaar and ECOSAR) identified between 17% and 25% of the compounds as expressing only baseline toxicity (narcosis). A smaller portion could be identified as reactive (19%) or specifically acting (2.7%), while the majority were non-assigned (61%). Overall environmental persistence, bioaccumulation and long-range transport potential were evaluated using structure-activity relationships and a multimedia fugacity-based model. A surprisingly high proportion of compounds (20%), mainly aromatic and halogenated, had a very high estimated persistence (>195 d). The proportion of compounds with a very high estimated bioconcentration or bioaccumulation factor (>5000) was substantially less (6.9%). Finally, a list was compiled of those compounds within the applicability domain of the models used, meeting both persistence and bioaccumulation criteria, and with a long-range transport potential comparable to PCB. This list of 68 potential persistent organic pollutants contained many well-known compounds (all halogenated), but notably also five fluorinated compounds that were not included in the EINECS inventory. This study demonstrates the usability of in silico tools for identification of potentially environmentally hazardous chemicals.     

Experimental studies on the ignition behavior of pure silane released into air

Silane is a well known pyrophoric gas which normally ignites upon contact with air. However, a silane release from a pressure source may not always lead to prompt ignition and frequently the ignition occurs when the release is shutoff. In a confined space, significant quantities of silane can accumulate prior to autoignition leading to an explosion, causing significant damage. To date, the mechanism and condition of pure silane ignition upon release into air has not been completely explained. Thus there is a need for additional experimental investigations covering a wide range of release conditions to enable a full understanding of silane ignition and explosion characteristics.This work presents a series of tests that aims to uncover the precise condition for pure silane ignition upon release into air. Tests were performed for releases at controlled and steady velocities. Steady flow of silane to a burn box and nitrogen to the desired vent stub are first established through mass flow controllers. An electrically controlled four-way switching valve is used to switch the silane and nitrogen flow such that steady silane flow without acceleration to the vent stub can be established. With careful control of vent conditions, we are able to find a reproducible critical exit velocity for prompt ignition of steady silane releases for different vent diameters. If the releases are reduced to below the critical exit velocity, prompt ignition of silane release is ensured. Above this critical exit velocity, silane can be released indefinitely into air without any ignition. The critical exit velocity is found to vary with the vent diameter. This relationship between the critical exit velocity and the vent diameter suggests that the silane release without prompt ignition was most likely caused by quench of the reactive kernel from the scalar dissipation between the release gas and the ambient air. Analysis of locations where prompt ignition occurred from the clips from high speed video camera found that the most reactive ignition kernel occurs in the range when the ratio of volumetric flow rate of entrained air to the silane flow reaches 0.322 ± 0.076, which is equivalent to the most reactive silane concentration of 75.6% in air. The implications from these results are discussed with emphasis on the safety of silane supply systems and operation practices.     

Criminalization of “galamsey” and livelihoods in Ghana: Limits and consequences

The fact that the artisanal and small-scale mining (ASM) sector in Ghana is driven largely by poverty means that the sector is a major source of livelihood for people in mining communities across the country. However, given the various social and environmental problems associated with the ASM sector, there is now an emerging consensus that the formalization of the sector would not only allow for these associated problems to be addressed but also ensures that the sector contributes to sustainable development and safeguard the livelihood of local communities. While a large body of extant literature has examined the challenges and opportunities facing the process of formalization, the question of the criminalization of the sector and its consequences for local livelihood has received only limited attention. Drawing from primary data collected during fieldwork in Ghana, this study examined the livelihood implications of the ban on galamsey in the Tarkwa-Nsuaem Municipality in South-Western Ghana from the perspectives of local communities and other key stakeholders. The study reveals that the ban on galamsey has imposed significant socio-economic hardships on the people and appears to be entrenching poverty rather than sustainable development. The study considers the theoretical and practical implications of the findings for sustainable livelihood enhancement in developing countries.     

Methods of characterizing the distribution of exhaust emissions from light-duty, gasoline-powered motor vehicles in the U.S. fleet

Mobile sources significantly contribute to ambient concentrations of airborne particulate matter (PM). Source apportionment studies for PM10 (PM < or = 10 microm in aerodynamic diameter) and PM2.5 (PM < or = 2.5 microm in aerodynamic diameter) indicate that mobile sources can be responsible for over half of the ambient PM measured in an urban area. Recent source apportionment studies attempted to differentiate between contributions from gasoline and diesel motor vehicle combustion. Several source apportionment studies conducted in the United States suggested that gasoline combustion from mobile sources contributed more to ambient PM than diesel combustion. However, existing emission inventories for the United States indicated that diesels contribute more than gasoline vehicles to ambient PM concentrations. A comprehensive testing program was initiated in the Kansas City metropolitan area to measure PM emissions in the light-duty, gasoline-powered, on-road mobile source fleet to provide data for PM inventory and emissions modeling. The vehicle recruitment design produced a sample that could represent the regional fleet, and by extension, the national fleet. All vehicles were recruited from a stratified sample on the basis of vehicle class (car, truck) and model-year group. The pool of available vehicles was drawn primarily from a sample of vehicle owners designed to represent the selected demographic and geographic characteristics of the Kansas City population. Emissions testing utilized a portable, light-duty chassis dynamometer with vehicles tested using the LA-92 driving cycle, on-board emissions measurement systems, and remote sensing devices. Particulate mass emissions were the focus of the study, with continuous and integrated samples collected. In addition, sample analyses included criteria gases (carbon monoxide, carbon dioxide, nitric oxide/nitrogen dioxide, hydrocarbons), air toxics (speciated volatile organic compounds), and PM constituents (elemental/organic carbon, metals, semi-volatile organic compounds). Results indicated that PM emissions from the in-use fleet varied by up to 3 orders of magnitude, with emissions generally increasing for older model-year vehicles. The study also identified a strong influence of ambient temperature on vehicle PM mass emissions, with rates increasing with decreasing temperatures.     

Enhancing the economic potential of organic waste by co-composting using ratio modelling toward a circular economy

Journal of Material Cycles and Waste Management - Co-composting, a circular economy approach to waste management, has economic potential and environmental benefits through nutrient recycling and...     

The forest environmental frontier in Russia: Between sustainable forest management discourses and ‘wood mining’ practice

With 20% of the world’s forests, Russia has global potential in bioeconomy development, biodiversity conservation and climate change mitigation. However, unsustainable forest management based on ‘wood mining’ reduces this potential. Based on document analysis, participant observations and interviews, this article shows how non-state actors—environmental NGOs and forest companies—address forest resource depletion and primary forest loss in Russia. We analyse two key interrelated forest discourses driven by non-state actors in Russia: (1) intensive forest management in secondary forests as a pathway towards sustained yield and primary forest conservation; (2) intact forest landscapes as a priority in primary forest conservation. We illustrate how these discourses have been integrated into policy debates, institutions and practices and discuss their relation to relevant global discourses. The article concludes that despite successful cases in conserving intact forest landscapes, there is still a frontier between sustainable forest management discourses and forestry practice in Russia.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-021-01643-6.     

Pragmatic Approaches for Water Management Under Climate Change Uncertainty1

Stakhiv, Eugene Z., 2011. Pragmatic Approaches for Water Management Under Climate Change Uncertainty. Journal of the American Water Resources Association (JAWRA) 47(6):1183–1196. DOI: 10.1111/j.1752‐1688.2011.00589.x Abstract: Water resources management is in a difficult transition phase, trying to accommodate large uncertainties associated with climate change while struggling to implement a difficult set of principles and institutional changes associated with integrated water resources management. Water management is the principal medium through which projected impacts of global warming will be felt and ameliorated. Many standard hydrological practices, based on assumptions of a stationary climate, can be extended to accommodate numerous aspects of climate uncertainty. Classical engineering risk and reliability strategies developed by the water management profession to cope with contemporary climate uncertainties can also be effectively employed during this transition period, while a new family of hydrological tools and better climate change models are developed. An expansion of the concept of “robust decision making,” coupled with existing analytical tools and techniques, is the basis for a new approach advocated for planning and designing water resources infrastructure under climate uncertainty. Ultimately, it is not the tools and methods that need to be revamped as much as the suite of decision rules and evaluation principles used for project justification. They need to be aligned to be more compatible with the implications of a highly uncertain future climate trajectory, so that the hydrologic effects of that uncertainty are correctly reflected in the design of water infrastructure.