Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “NO3”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on BiTeNO6 by Materials Project

Bi(TeO3)(NO3) crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Bi3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Bi–O bond distances ranging from 2.24–2.87 Å. N5+ is bonded in a trigonal planar geometry to three O2- atoms. There is two shorter (1.26 Å) and one longer (1.29 Å) N–O bond length. Te4+ is bonded in a 3-coordinate geometry to three O2- atoms. There are a spread of Te–O bond distances ranging from 1.90–1.94 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one N5+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Bi3+ and one Te4+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Bi3+ and one Te4+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Bi3+ and one Te4+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Bi3+ and one N5+ atom. In the sixth O2- site, O2- is bonded in a single-bond geometry to one Bi3+ and one N5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on RhN7ClO6 by Materials Project

RhNCl(N2)2(NO3)2 crystallizes in the tetragonal I4 space group. The structure is zero-dimensional and consists of eight ammonia molecules, four nitric acid molecules, and two RhNCl clusters. In each RhNCl cluster, Rh4+ is bonded in a distorted single-bond geometry to one N+1.29+ and one Cl1- atom. The Rh–N bond length is 1.70 Å. The Rh–Cl bond length is 2.57 Å. N+1.29+ is bonded in a single-bond geometry to one Rh4+ atom. Cl1- is bonded in a distorted single-bond geometry to one Rh4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cu3Pb2Se2(NO7)2 by Materials Project

Cu3Pb2(SeO4)2(NO3)2 crystallizes in the orthorhombic Cmc2_1 space group. The structure is two-dimensional and consists of eight nitric acid molecules and two Cu3Pb2(SeO4)2 sheets oriented in the (0, 0, 1) direction. In each Cu3Pb2(SeO4)2 sheet, there are two inequivalent Cu2+ sites. In the first Cu2+ site, Cu2+ is bonded in a square co-planar geometry to four O2- atoms. There are a spread of Cu–O bond distances ranging from 1.92–1.99 Å. In the second Cu2+ site, Cu2+ is bonded in a square co-planar geometry to four O2- atoms. There are a spread of Cu–O bond distances ranging from 1.95–1.97 Å. There are two inequivalent Pb4+ sites. In the first Pb4+ site, Pb4+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Pb–O bond distances ranging from 2.42–2.54 Å. In the second Pb4+ site, Pb4+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Pb–O bond distances ranging from 2.47–2.54 Å. There are two inequivalent Se2+ sites. In the first Se2+ site, Se2+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. All Se–O bond lengths are 1.74 Å. In the second Se2+ site, Se2+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. All Se–O bond lengths are 1.74 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded to three Cu2+ and one Pb4+ atom to form distorted corner-sharing OCu3Pb tetrahedra. In the second O2- site, O2- is bonded to three Cu2+ and one Pb4+ atom to form distorted corner-sharing OCu3Pb tetrahedra. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to one Cu2+, one Pb4+, and one Se2+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one Cu2+, one Pb4+, and one Se2+ atom. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Cu2+, one Pb4+, and one Se2+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one Cu2+, one Pb4+, and one Se2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Co(NO6)2 by Materials Project

CoO6(NO3)2 crystallizes in the monoclinic C2/c space group. The structure is zero-dimensional and consists of four cobalt;hexahydrate molecules and eight nitric acid molecules.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on RhN7ClO6 by Materials Project

RhNCl(N2)2(NO3)2 crystallizes in the tetragonal I4 space group. The structure is zero-dimensional and consists of eight ammonia molecules, four nitric acid molecules, and two RhNCl clusters. In each RhNCl cluster, Rh4+ is bonded in a distorted single-bond geometry to one N+1.29+ and one Cl1- atom. The Rh–N bond length is 1.72 Å. The Rh–Cl bond length is 2.62 Å. N+1.29+ is bonded in a single-bond geometry to one Rh4+ atom. Cl1- is bonded in a single-bond geometry to one Rh4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Th(N4O9)2 by Materials Project

Th(NO3)6N2 is Brookite-like structured and crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four ammonia molecules and two nitric acid;thorium molecules.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NO6 by Materials Project

(NO3)2(O2)3 crystallizes in the orthorhombic P2_12_12_1 space group. The structure is zero-dimensional and consists of four nitric acid molecules and four trioxidane molecules.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Zn5H2(NO7)2 by Materials Project

Zn5(HO4)2(NO3)2 crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of four nitric acid molecules and two Zn5(HO4)2 sheets oriented in the (1, 0, 0) direction. In each Zn5(HO4)2 sheet, there are three inequivalent Zn sites. In the first Zn site, Zn is bonded to six O atoms to form ZnO6 octahedra that share corners with four equivalent ZnHO3 tetrahedra and edges with four ZnO6 octahedra. There are a spread of Zn–O bond distances ranging from 2.01–2.07 Å. In the second Zn site, Zn is bonded to one H and three O atoms to form corner-sharing ZnHO3 tetrahedra. The corner-sharing octahedra tilt angles range from 55–56°. The Zn–H bond length is 1.67 Å. There is one shorter (1.94 Å) and two longer (1.95 Å) Zn–O bond length. In the third Zn site, Zn is bonded to six O atoms to form ZnO6 octahedra that share corners with four equivalent ZnHO3 tetrahedra and edges with four equivalent ZnO6 octahedra. There are two shorter (2.01 Å) and four longer (2.06 Å) Zn–O bond lengths. H is bonded in a single-bond geometry to one Zn atom. There are three inequivalent O sites. In the first O site, O is bonded in a trigonal planar geometry to three Zn atoms. In the second O site, O is bonded in a trigonal planar geometry to three Zn atoms. In the third O site, O is bonded in a trigonal non-coplanar geometry to three Zn atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AgH36S8N11O18 by Materials Project

Ag(S2O3)4(NH4)9(NO3)2 crystallizes in the tetragonal I-42d space group. The structure is zero-dimensional and consists of thirty-six ammonium molecules, eight nitric acid molecules, and four Ag(S2O3)4 clusters. In each Ag(S2O3)4 cluster, Ag1+ is bonded in a tetrahedral geometry to four equivalent S2- atoms. All Ag–S bond lengths are 2.59 Å. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a trigonal non-coplanar geometry to one S2- and three O2- atoms. The S–S bond length is 2.04 Å. All S–O bond lengths are 1.49 Å. In the second S2- site, S2- is bonded in a distorted water-like geometry to one Ag1+ and one S2- atom. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one S2- atom. In the second O2- site, O2- is bonded in a single-bond geometry to one S2- atom. In the third O2- site, O2- is bonded in a single-bond geometry to one S2- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CeMg(NO4)6 by Materials Project

MgO6Ce(NO3)6 is Halite, Rock Salt structured and crystallizes in the cubic Pa-3 space group. The structure is zero-dimensional and consists of four magnesium;dihydroxide;tetrahydrate molecules and four nsc 4314 molecules.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on UH18C4N10O13 by Materials Project

UC4N8H18O7(NO3)2 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of eight nitric acid molecules and four UC4N8H18O7 clusters. In each UC4N8H18O7 cluster, U6+ is bonded in a distorted pentagonal bipyramidal geometry to seven O2- atoms. There are a spread of U–O bond distances ranging from 1.81–2.50 Å. There are four inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a trigonal planar geometry to two N+1.40- and one O2- atom. Both C–N bond lengths are 1.34 Å. The C–O bond length is 1.29 Å. In the second C4+ site, C4+ is bonded in a trigonal planar geometry to two N+1.40- and one O2- atom. Both C–N bond lengths are 1.34 Å. The C–O bond length is 1.28 Å. In the third C4+ site, C4+ is bonded in a trigonal planar geometry to two N+1.40- and one O2- atom. There is one shorter (1.34 Å) and one longer (1.35 Å) C–N bond length. The C–O bond length is 1.28 Å. In the fourth C4+ site, C4+ is bonded in a trigonal planar geometry to two N+1.40- and one O2- atom. Both C–N bond lengths are 1.34 Å. The C–O bond length is 1.28 Å. There are eight inequivalent N+1.40- sites. In the first N+1.40- site, N+1.40- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. There is one shorter (1.01 Å) and one longer (1.02 Å) N–H bond length. In the second N+1.40- site, N+1.40- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. There is one shorter (1.01 Å) and one longer (1.02 Å) N–H bond length. In the third N+1.40- site, N+1.40- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. Both N–H bond lengths are 1.02 Å. In the fourth N+1.40- site, N+1.40- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. Both N–H bond lengths are 1.02 Å. In the fifth N+1.40- site, N+1.40- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. Both N–H bond lengths are 1.02 Å. In the sixth N+1.40- site, N+1.40- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. Both N–H bond lengths are 1.02 Å. In the seventh N+1.40- site, N+1.40- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. There is one shorter (1.01 Å) and one longer (1.02 Å) N–H bond length. In the eighth N+1.40- site, N+1.40- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. There is one shorter (1.01 Å) and one longer (1.03 Å) N–H bond length. There are eighteen inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one N+1.40- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one N+1.40- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one N+1.40- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one N+1.40- atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one N+1.40- atom. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one N+1.40- atom. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one N+1.40- atom. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one N+1.40- atom. In the ninth H1+ site, H1+ is bonded in a single-bond geometry to one N+1.40- atom. In the tenth H1+ site, H1+ is bonded in a single-bond geometry to one N+1.40- atom. In the eleventh H1+ site, H1+ is bonded in a single-bond geometry to one N+1.40- atom. In the twelfth H1+ site, H1+ is bonded in a single-bond geometry to one N+1.40- atom. In the thirteenth H1+ site, H1+ is bonded in a single-bond geometry to one N+1.40- atom. In the fourteenth H1+ site, H1+ is bonded in a single-bond geometry to one N+1.40- atom. In the fifteenth H1+ site, H1+ is bonded in a single-bond geometry to one N+1.40- atom. In the sixteenth H1+ site, H1+ is bonded in a single-bond geometry to one N+1.40- atom. In the seventeenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the eighteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one U6+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one U6+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to one U6+ and one C4+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to one U6+ and one C4+ atom. In the fifth O2- site, O2- is bonded in a 1-coordinate geometry to one U6+ and one C4+ atom. In the sixth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one U6+ and one C4+ atom. In the seventh O2- site, O2- is bonded in a distorted water-like geometry to one U6+ and two H1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Physical, resource supply, and biological controls on nutrient processing along the river continuum

Nutrient impairment has led to damages to US surface and groundwater systems in excess of 100 billion dollars per year. Therefore, there is a strong need to develop methods to predict the transport, uptake, and export of nutrients along fluvial networks. We present results that are based on a data-driven mechanistic understanding of three factors that largely control nutrient uptake and export: 1) interactions between transport-related processes (mass transfer to metabolically active zones), 2) resource supply dynamics (nutrient concentration, stoichiometric constraints, etc.), and 3) biological controls (microbial community structure and function). Our results were generated from column experiments conducted along the Jemez River-Rio Grande continuum, which spans four orders of magnitude in mean annual discharge, more than 2000 m in altitude, and more than 500 km of stream longitude. Two resource supply injections were performed on each of the columns, i.e., a nitrate only addition, followed by a stoichiometrically ‘balanced’ 106Carbon:16Nitrogen:1Phosphorus addition. We quantified NO3-N uptake kinetics while constraining three variables: stream order, sediment type and type of injection (N vs stoichiometrically ‘balanced’ C:N:P). Following the laboratory nutrient uptake experiments, the columns were destructively sampled and the contents were homogenized to collect subsamples for DNA sequencing. Amplicon analysis was carried out as described by the Earth Microbiome Protocol for 16s and ITS sequencing.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

Strontium Speciation in Relevant Tank Waste Components Examined by Electrospray Ionization Mass Spectrometry

The identification of chemical species formed in complex nuclear waste is crucial for the development and employment of advanced separations technologies to remediate the Hanford site by processing tank waste. The current Tank Side Cesium Removal (TSCR) process deployed at Hanford utilizes crystalline silicotitanate (CST) ion exchange (IX) media to aid in the separation of low-activity waste for proper treatment and disposal. The inorganic IX media is highly selective for Cs but has been shown to also remove Sr from caustic simulants and small-scale IX processing of Hanford tank waste.(Fiskum, Rovira et al. 2019, Fiskum, Campbell et al. 2021, Westesen, Campbell et al. 2022) Quantitative Sr removal has not been observed in all tank waste supernates tested; thus, to better understand Sr removal and effectively predict processing behavior through TSCR, it is necessary to first investigate Sr speciation in tank waste. This work utilized electrospray ionization mass spectrometry (ESI-MS) to identify ionic Sr complexes that form in the presence of NO 3 –, NO 2 –, OH–, and Cl–. Although our results show that NO 3 –, NO 2 –, and OH– are competitive for Sr 2+ binding, previous data from IX studies indicate that [SrOH] + is not the dominant species of concern in tank waste processing schemes.(Fiskum, Campbell and Trang-Le 2020) Our results show that the [Sr(NO3)]+ species and the [Sr(NO2)] + species form in considerable abundances, which may affect the ability to separate Sr using CST in nuclear waste separation processes.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Second ARM Aerosol Chemical Speciation Monitor Users’ Meeting Report

The aerosol chemical speciation monitor (ACSM) was developed to adapt the technology of the aerosol mass spectrometer (AMS) to routine, long-term, standalone monitoring. The calculation of particulate mass concentration from ACSM data requires the measurement of the response of the instrument to aerosol of specific size and composition as well as assumptions about the instrument response based on laboratory measurements and field experience acquired over more than two decades of operation of AMS and a decade of operation of the ACSM. Three parameters in the concentration calculations that are particularly important are the NO3 response factor (RFNO3), relative ionization efficiency (RIE), and the collection efficiency (CE). The values of RFNO3 and RIEs are determined from calibration, however the jump calibration method previously used in calibration can result in errors in the RIE for sulfate. This has been corrected by implementing a continuous calibration method. The default collection efficiency is 0.5. This has been shown to result in mass loadings that do not agree with mass determinations from other instruments because of effects of composition on the vaporization of the particles. The previous work of investigators addressing this issue is discussed. After preliminary work on ACSM and scanning mobility particle sizer (SMPS) data from the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) user facility Southern Great Plains (SGP) observatory collected in late 2016 and 2017 produced a parameterization of composition dependent collection efficiency very different from the results of previous studies, SMPS data were examined and we determined that there was significant mass that the instrument did not capture because the particles with diameters larger than 465 nm are not counted by this instrument. Data for the ultra-high-sensitivity aerosol spectrometer (UHSAS), SMPS, and ACSM are available for nearly all of 2019. The data from UHSAS and SMPS collected in 2019 were compared. We found that the UHSAS data has particle counts and total volumes significantly less than measured by the condensation particle counter (CPC) and SMPS. The SMPS data were extended by fitting the average volume distribution with a log normal curve and using this relationship to estimate a mass value for the SMPS over extended diameter range. The extended SMPS mass values result in a CDCE parameterization that is in better agreement with the results of other investigators, but is still different from other formulations. The working group recommends that the ACSM data be processed with a collective efficiency (CE)=1, that this be documented clearly in the metadata, and the use of the default CE of 0.5 or a formulation of composition-dependent collection efficiencies (CDCE) chosen by the user should be implemented based on the ammonium nitrate mass fraction. This is clearly necessary for the wintertime SGP ACSM data because of the high nitrate concentrations.

47 OTHER INSTRUMENTATION↗
DOE OSTI2020

Environmental impacts of dam reservoir filling in the East Amazon

Mitigating the environmental impacts caused by hydroelectric dams is a worldwide challenge. The aquatic ecosystem is the most impacted during the reservoir filling phase, yet biogeochemical dynamics at this stage are not well-studied. Here we evaluate water quality and hydraulic parameters in the Araguari River (Amapá/Brazil) during the filling of the Ferreira Gomes Hydroelectric Power Plant reservoir (UHEFG). Five field campaigns were performed from July 2014 to August 2015 across nine sample sites within the reservoir (P1, P2, …P9) and only one downstream (P10). The following key variables were monitored: Trophic State Index (TSI), Total Coliforms (TC), E. coli (EC) and Chlorophyll-a (Chl-a), along with physical and chemical variables (Temperature, Suspended Solids, Total Dissolved Solids, Electrical Conductivity, Turbidity, Color, pH, DO, Al3+, NH4+, Cl-, Mg1+, Ca2+, total Phosphorous, NH3, NO3-, and SO42). Besides that, hydraulic-operational variables were also investigated: inflows (Qa), outflows (Qd), and variation in reservoir volume (Vol%). Multiple Regression Analyses showed that the key parameters were both significantly influenced by physio-chemical and hydraulic variables (0.46=R2adj=0.99, p<0.05). The DO showed significant spatial variation, being influenced by the turbulence from the Coaracy Nunes dam (UHECN) upstream and the UHEFG dam downstream. The Vol% influenced the TSI, which ranged from oligotrophic to hypertrophic and eventually stabilized at mesotrophic. The levels of TSI, TC, and Chl-a decreased and the level of E. coli increased (p<0.05) as a function of Vol%. A Cluster Analysis showed the formation of three spatial groups - two inside the reservoir and one downstream (P10). This suggests that in the rainy season or transition season, the hydraulic residence time in the reservoir is very low (16 = thr = 36 h) when hydrodynamic processes are dominant. In the dry season (thr ˜ 1 month), biogeochemical and hydrodynamic processes occur at similar time scales to the nutrient and microbial abundance. These results confirm the hypothesis that the filling phase has significant impacts on the key parameters of the water quality (p<0.05). We conclude that the filling phase of the UHEFG reservoir generated significant environmental impacts, which have repercussions even retrospectively.

Amazon, biogeochemistry, ecosystem, extreme event,↗
DOE OSTI2021

Data from: Niche differentiation of bacterial versus archaeal soil nitrifiers induced by ammonium inhibition along a management gradient

Soil nitrification, mediated mainly by ammonia oxidizing archaea (AOA) and bacteria (AOB), converts ammonium (NH4+) to nitrite (NO2−) and thence nitrate (NO3−). To better understand ecological differences between AOA and AOB, we investigated the nitrification kinetics of AOA and AOB under eight replicated cropped and unmanaged ecosystems (including two fertilized natural systems) along a long-term management intensity gradient in the upper U.S. Midwest. For five of eight ecosystems, AOB but not AOA exhibited Haldane kinetics (inhibited by high NH4+ additions), especially in perennial and successional systems. In contrast, AOA predominantly exhibited Michaelis-Menten kinetics, suggesting greater resistance to high nitrogen inputs than AOB. These responses suggest the potential for NH4+-induced niche differentiation between AOA and AOB. Additionally, long-term fertilization significantly enhanced maximum nitrification rates (Vmax) in the early successional systems for both AOA and AOB, but not in the deciduous forest systems. This was likely due to pH suppression of nitrification in the acidic forest soils, corroborated by a positive correlation of Vmax with soil pH but not with amoA gene abundance. Results also demonstrated that soil nitrification potentials were relatively stable, as there were no seasonal differences. Overall, results suggest that (1) NH4+ inhibition of AOB but not AOA could be another factor contributing to niche differentiation between AOA and AOB in soil, and (2) nitrification by both AOA and AOB can be significantly promoted by long-term nitrogen inputs.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Chemical properties and single-particle mixing state of soot aerosol in Houston during the TRACER campaign

Abstract. A high-resolution soot particle aerosol mass spectrometer (SP-AMS) was used to selectively measure refractory black carbon (rBC) and its associated coating material using both the ensemble size-resolved mass spectral mode and the event trigger single particle (ETSP) mode in Houston, Texas, in summer 2022. This study was conducted as part of the Department of Energy Atmospheric Radiation Measurement (ARM) program's TRacking Aerosol Convection interactions ExpeRiment (TRACER) field campaign. The study revealed an average (±1σ) rBC concentration of 103 ± 176 ng m−3. Additionally, the coatings on the BC particles were primarily composed of organics (59 %; 219 ± 260 ng m−3) and sulfate (26 %; 94 ± 55 ng m−3). Positive matrix factorization (PMF) analysis of the ensemble mass spectra of BC-containing particles resolved four distinct types of soot aerosol, including an oxidized organic aerosol (OOABC,PMF) factor associated with processed primary organic aerosol, an inorganic sulfate factor (SO4,BC,PMF), an oxidized rBC factor (O-BCPMF), and a mixed mineral dust–biomass burning aerosol factor with significant contribution from potassium (K-BBBC,PMF). Additionally, K-means clustering analysis of the single-particle mass spectra identified eight different clusters, including soot particles enriched in hydrocarbon-like organic aerosol (HOABC,ETSP), sulfate (SO4,BC,ETSP), two types of rBC, OOA (OOABC,ETSP), chloride (ClBC,ETSP), and nitrate (NO3,BC,ETSP). The single-particle measurements demonstrate substantial variation in BC coating thickness with coating-to-rBC mass ratios ranging from 0.1 to 100. The mixing state index (χ), which denotes the degree of homogeneity of the soot aerosol, varied from 4 % to 94 % with a median of 40 %, indicating that the aerosol population lies in between internal and external mixing but has large temporal and source type variability. In addition, a significant fraction of BC-containing particles, a majority enriched with oxidized organics and sulfate, exhibit sufficiently high κ values and diameters conducive to activation as cloud nuclei under atmospherically relevant supersaturation conditions. This finding bears significance in comprehending the aging processes of rBC-containing particles and their activation into cloud droplets. Our analysis highlights the complex nature of soot aerosol and underscores the need to comprehend its variability across different environments for accurate assessment of climate change.

54 ENVIRONMENTAL SCIENCES↗