Particulate Emissions from in-use Commercial Aircraft

Particulate emission indices (per kg fuel) have been determined by sampling the advected plumes of in-use commercial aircraft at two different airports using a novel approach. Differences are observed in the number, magnitude, and composition of the particle emissions between idle and take-off. At the first airport, Electrical Low Pressure Impactor (ELPI) data indicate that number based emission indices (EI _n ) vary by an order of magnitude for take-off plumes from different aircraft. Additionally, EI _n values for idle plumes are greater than take-off. At the second airport, EI _n values derived from condensation particle counter (CPC) measurements span ～ an order of magnitude (3–50 × 10 ¹⁵ particles per kg fuel). The median values of the idle and take-off plumes were 1.8 × 10 ¹⁶ and 7.6 × 10 ¹⁵ particles per kg fuel, respectively. For take-off plumes, the magnitude of the particulate emission index is not correlated with NO _x at either airport. The surface properties of the particulate emissions in take-off and idle plumes differ significantly as measured by diffusion charging (DC) and photoelectric aerosol sensor (PAS) instruments. Results indicate that take-off plumes are characterized by particles with photoelectric-active surfaces, presumably elemental carbon, whereas idle plumes are composed of non-photoelectric-active constituents and coated soot particles. Measurements of the particulate size distribution (ELPI) show evidence for two modes, one at ～ 90 nm aerodynamic diameter and a second mode at or below the instrument cutoff ( < 30 nm).     

Emissions and radiative impacts of sub-10 nm particles from biofuel and fossil fuel cookstoves

Abstract

Combustion sources have been shown to directly emit particles smaller than 10?nm. The emission of 1-3?nm particles from biofuel or fossil fuel cookstoves has not been studied previously, nor have the radiative impacts of these emissions been investigated. In this work, emissions (number of particles) were measured during a water boiling test performed on five different cookstoves (three-stone fire, rocket elbow, gasifier, charcoal, and liquified petroleum gas [LPG]) for particle diameters between ～1 and ～1000?nm. We found significant emissions of particles smaller than 10?nm for all cookstoves (>5?×?10¹⁵ # kg-fuel^?1). Furthermore, cleaner (e.g., LPG) cookstoves emitted a larger fraction of sub-10?nm particles (relative to the total particle counts) than traditional cookstoves (e.g., three-stone fire). Simulations performed with the global chemical transport model GEOS-Chem-TOMAS that were informed by emissions data from this work suggested that sub-10?nm particles were unlikely to significantly influence number concentrations of particles with diameters larger than 80?nm that can serve as cloud condensation nuclei (CCN) (<0.3%, globally averaged) or alter the cloud-albedo indirect effect (absolute value <0.005?W m^?2, globally averaged). The largest, but still relatively minor, localized changes in CCN-relevant concentrations (<10%) and the cloud-albedo indirect effect (absolute value <0.5?W m^?2) were found in large biofuel combustion source regions (e.g., Brazil, Tanzania, Southeast Asia) and in the Southern Ocean. Enhanced coagulation-related losses of these sub-10?nm particles at sub-grid scales will tend to further reduce their impact on particle number concentrations and the aerosol indirect effect, although they might still be of relevance for human health.

Copyright © 2020 American Association for Aerosol Research     

The promise of piezoelectric polymers

Recent advances provide new opportunities in the field of polymer piezoelectric materials. Piezoelectric materials provide unique insights to the fundamental understanding of the solid state. In addition, piezoelectric materials have a wide range of applications, representing billions of dollars of commercial applications. However, inorganic piezoelectric materials have limitations that polymer ferroelectric materials can overcome, if certain challenges can be addressed. This mini‐review is a practical summary of the current research and future directions in the investigation and application of piezoelectric materials with an emphasis on polymeric piezoelectric materials. We will assume that the reader is well versed in the subject of polymers, but not as familiar with piezoelectric materials. © 2018 Society of Chemical Industry     

Diet and trophic niche space and overlap of Lake Ontario salmonid species using stable isotopes and stomach contents

Lake Ontario supports a diversity of native and non-native salmonids which are managed largely through stocking practices. Ecological changes (e.g., invasive species) altering the food web structure accompanied with shifts in prey abundance, necessitate understanding the trophic niches of Lake Ontario salmonids to aid in management. The objectives of this study were to quantify salmonid (5 species) trophic niches and dietary proportions using stable isotope ratios (δ¹³C and δ¹⁵N) of a large sample set (adult fish (>300?mm; n?=?672) and key offshore prey (5 species, n?=?2037)) collected across Lake Ontario in 2013. Estimates of prey based on stable isotope ratios were similar to stomach contents. Based on stable isotope ratios, non-native prey dominated salmonid diet; in particular alewife (Alosa pseudoharengus) constituted the majority (0.31 to 0.93) of all salmonid diets, and round goby (Neogobius melanostomus) contributed 0.26 and 0.19 of brown trout (Salmo trutta) and lake trout (Salvelinus namaycush) diets, respectively. Trophic niche overlap was high between all salmonids, except lake trout. The largest trophic niche overlap occurred between Chinook (Oncorhynchus tshawytscha), coho (Oncorhynchus kisutch), and Atlantic salmon (Salmo salar), and their reliance on alewife infers a strong pelagic foraging strategy. Lake, brown and rainbow (Oncorhynchus mykiss) trout had larger and/or more distinct trophic niches indicative of a more variable diet across individuals and utilizing different foraging strategies and/or habitats. Overall, Lake Ontario salmonids maintained a high reliance on alewife, and their potential for plasticity in diet provides important information to management regarding population sustainability.