Dataset associated with "Effects of fuel moisture content on emissions from a rocket-elbow cookstove"

This dataset includes cookstove emissions data per energy delivered and per mass of fuel burned. Emissions data on a per-energy-delivered basis have units of grams per megajoule delivered. Emissions data on a per-mass-of-fuel-burned basis have units of grams per kilogram of fuel. These data were collected in a laboratory cookstoves testing facility at Colorado State University. The data file includes the following columns: 1. test_id - test ID (used internally to identify test replicates), 2. date - date on which the test replicate was conducted, 3. stove - name of the stove model tested, 4. fuel - name of the fuel, 5. fuel_shape - shape of the fuel, either "Milled" or "Split", 6. mc_level - moisture level of the fuel, either "Low", "Medium", or "High", 7. fuel_mc_dry - the moisture content of the fuel on a dry mass basis, in percent, 8. pollutant - name of the pollutant, 9. value - value of the emissions metric, 10. units - units associated with the emission metric, either "g_MJd" or "g_pol_kg_fuel".Exposure to air pollution from solid-fuel cookstoves is a leading risk factor for premature death; however, the effect of fuel moisture content on air pollutant emissions from solid-fuel cookstoves remains poorly constrained. The objective of this work was to characterize emissions from a rocket-elbow cookstove burning wood at three different moisture levels (5%, 15%, and 25% on a dry mass basis). Emissions of CO2, carbon monoxide (CO), methane, formaldehyde, acetaldehyde, benzene, toluene, ethylbenzene, xylenes, fine particulate matter (PM2.5), elemental carbon (EC), and organic carbon (OC) were measured. Emission factors (EFs; g·MJdelivered-1) for all pollutants, except CO2 and EC, increased with increasing fuel moisture content: CO EFs increased by 84%, benzene EFs increased by 82%, PM2.5 EFs increased by 149%, and formaldehyde EFs increased by 216%. Both modified combustion efficiency and the temperature at the combustion chamber exit decreased with increasing fuel moisture, suggesting that the energy required to vaporize water in the fuel led to lower temperatures in the combustion chamber and lower gas-phase oxidation rates. These results illustrate that changes in fuel equilibrium moisture content could cause EFs for pollutants such as PM2.5 and formaldehyde to vary by a factor of two or more across different geographic regions.This work was supported by grant ES023688 from the National Institute for Environmental Health Sciences.This work was supported by grant RD83543801 from the U.S. Environmental Protection Agency

Investigating drivers of particulate matter pollution over India and the implications for radiative forcing with GEOS-Chem-TOMAS15: Data and code

Ambient fine particulate matter (PM2.5) concentrations in India frequently exceed 100 mg/m3 during fall and winter pollution episodes. We use the GEOS-Chem chemical transport model with the TwO-Moment Aerosol Sectional microphysics scheme with 15 size bins (TOMAS15) to assess PM2.5 composition and impacts on radiation and cloud condensation nuclei (CCN) during pollution episodes as compared to the seasonal (October-December) average. We conduct high resolution (0.25°x0.3125°) nested-domain simulations over India for short-duration, high-PM2.5 episodes in fall 2015 and 2017. The simulations capture the magnitude and spatial patterns of pollution episodes measured by surface monitors (r2PM2.5=0.69) although aerosol optical depth is underestimated. During the episodes, near-surface organic matter (OM), black carbon (BC), and secondary inorganic aerosol concentrations increase from seasonal averages by up to 36, 7, and 7 µg/m3, respectively. Episodic aerosol increases enhance cooling by lowering the top-of-atmosphere clear-sky direct radiative effect (DRETOA) during the 2015 episode (-6 W/m2), with a smaller impact during the 2017 episode (-1 W/m2). Differences in DRETOA reflect larger increases in scattering aerosols in the column during the 2015 episode (+17 mg/m2) than in 2017 (+13 mg/m2), while absorbing aerosol column enhancements are smaller (+3 mg/m2) in both years. Changes in shortwave radiation at the surface (SWsfc) are spatially similar to DRETOA and mostly negative during both episodes. CCN enhancements during these episodes occur across the western Indo-Gangetic Plain, coincident with higher PM2.5 concentrations. Changes in DRETOA, SWsfc, and CCN during high-PM2.5 episodes may have implications for crops, the hydrologic cycle, and surface temperature

Development of optically pure pyrethroid-like fluorescent substrates for carboxylesterases

Pyrethroids are now the world's most extensively used insecticides. One of the common metabolic routes of pyrethroid insecticides in living systems is hydrolysis by carboxylesterases, and this hydrolysis may be stereospecific since most pyrethroid insecticides have chiral centers. In previous studies, pyrethroid-like fluorescent substrates have been shown to be hydrolyzed in a fashion similar to actual pyrethroids. It is important to synthesize the stereoisomers of pyrethroid-like fluorescent substrates to study the stereointeraction between carboxylesterases and these substrates. In this study, an effective synthetic method for preparing optically enriched (R)- and (S)-α-2-hydroxy-2-(6-methoxy-2-naphthyl)acetonitrile was developed. With this alcohol, an efficient synthetic route for preparation of optically pure cypermethrin and fenvalerate analogues was provided. Identification of these stereoisomers was determined based on GC, HPLC, 1H NMR, and X-ray crystallography. In addition, stereointeraction between carboxylesterases and chiral fluorescent substrates indicated that (i) stereospecificity of recombinant mouse liver carboxylesterases (NCBI accession nos. BAC36707 and NM_133960) varied significantly (up to 300-fold difference) with different stereoisomers of cypermethrin and fenvalerate analogues; (ii) on the basis of Vmax, the sensitivity of this analytical method, using a single stereoisomer of cypermethrin analogues instead of a mixture of eight stereosiomers, could be enhanced by 4−6 times for detection of these carboxylesterases; and (iii) possible usage of these carboxylesterases for chiral synthesis is discussed