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Journal ArticleDOI

OH-initiated heterogeneous oxidation of tris-2-butoxyethyl phosphate: implications for its fate in the atmosphere

19 Nov 2014-Atmospheric Chemistry and Physics (Copernicus GmbH)-Vol. 14, Iss: 22, pp 12195-12207
TL;DR: In this paper, a particle-phase relative rates technique is used to investigate the heterogeneous reaction between OH radicals and tris-2-butoxyethyl phosphate (TBEP) at 298 K by combining aerosol time-of-flight mass spectrometry (C-ToF-MS) data and positive matrix factor (PMF) analysis.
Abstract: . A particle-phase relative rates technique is used to investigate the heterogeneous reaction between OH radicals and tris-2-butoxyethyl phosphate (TBEP) at 298 K by combining aerosol time-of-flight mass spectrometry (C-ToF-MS) data and positive matrix factor (PMF) analysis. The derived second-order rate constants (k2) for the heterogeneous loss of TBEP is (4.44 ± 0.45) × 10−12 cm3 molecule−1 s−1, from which an approximate particle-phase lifetime was estimated to be 2.6 (2.3–2.9) days. However, large differences in the rate constants for TBEP relative to a reference compound were observed when comparing internally and externally mixed TBEP/organic particles, and upon changes in the RH. The heterogeneous degradation of TBEP was found to be depressed or enhanced depending upon the particle mixing state and phase, highlighting the complexity of heterogeneous oxidation in the atmosphere. The effect of gas-particle partitioning on the estimated overall lifetime (gas + particle) for several organophosphate esters (OPEs) was also examined through the explicit modeling of this process. The overall atmospheric lifetimes of TBEP, tris-2-ethylhexyl phosphate (TEHP) and tris-1,3-dichloro-2-propyl phosphate (TDCPP) were estimated to be 1.9, 1.9 and 2.4 days respectively, and are highly dependent upon particle size. These results demonstrate that modeling the atmospheric fate of particle-phase toxic compounds for the purpose of risk assessment must include the gas-particle partitioning process, and in the future include the effect of other particulate components on the evaporation kinetics and/or the heterogeneous loss rates.

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Citations
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Journal ArticleDOI
TL;DR: The results suggested that the degradation of α-pinene via the ozonization in the atmosphere may be affected greatly by RH, as well as the presence of aerosol particles.
Abstract: The α-pinene ozonolysis under the different environmental conditions were observed in a smog chamber. The second-order rate constant (k) was determined to be (7.25±0.06)×10-17cm3/(molecule·sec) under 20% of relative humidity (RH) and room temperature. RH showed a marked influence on the α-pinene ozonolysis. The value of k increased with RH increase, which was 1.6 times faster at RH=80% than that at RH=20%. Additionally, the value of k apparently changed in the presence of the aerosol particles. The diesel soot increased the k value. The fly ash prohibited the reaction, however, H2SO4-treated fly ash promoted the reaction. The information of products gained using FT-IR and SPAMS showed that pinonic acid, 10-hydroxy-pinonic acid and pinic acid could be generated during the α-pinene ozonolysis. Water molecules could take part in the formation of the products, and play a vital role in the degradation of α-pinene. The atmospheric residence time calculation showed that the ozonolysis in the atmosphere is an important way of the α-pinene consumption as compared to that reacted with OH during daytime. The results suggested that the degradation of α-pinene via the ozonization in the atmosphere may be affected greatly by RH, as well as the presence of aerosol particles. The ozonolysis reaction may be an important way of the α-pinene consumption during daytime.

11 citations

Journal ArticleDOI
TL;DR: Comparisons of the gas/particle (G/P) partitioning equilibrium models indicated that the Dachs-Eisenreich (D-E) model estimates were more reliable than the other models in this study and the current OPE levels in the test home were within the safe thresholds.

7 citations

Journal ArticleDOI
Abstract: Transformation of organophosphate esters (OPEs) in natural ambient air and potential health risks from coexposure to OPEs and their transformation products are largely unclear. Therefore, a novel framework combining field-based investigation, in silico prediction, and target and suspect screening was employed to understand atmospheric persistence and health impacts of OPEs. Alkyl-OPE transformation products ubiquitously occurred in urban ambient air. The transformation ratios of tris(2-butoxyethyl) phosphate were size-dependent, implying that transformation processes may be affected by particle size. Transformation products of chlorinated- and aryl-OPEs were not detected in atmospheric particles, and atmospheric dry deposition might significantly contribute to their removal. Although inhalation risk of coexposure to OPEs and transformation products in urban ambient air was low, health risks related to OPEs may be underestimated as constrained by the identification of plausible transformation products and their toxicity testing in vitro or in vivo at current stage. The present study highlights the significant impact of particle size on the atmospheric persistence of OPEs and suggests that health risk assessments should be conducted with concurrent consideration of both parental compounds and transformation products of OPEs, in view of the nonnegligible abundances of transformation products in the air and their potential toxicity in silico.

5 citations

01 May 2010
TL;DR: In this article, the uptake of NO3 and N2O5 to Saharan dust, ambient aerosols and soot was investigated using a simple relative rate method with simultaneous detection of both trace gases.
Abstract: Abstract. The uptake of NO3 and N2O5 to Saharan dust, ambient aerosols and soot was investigated using a novel and simple relative rate method with simultaneous detection of both NO3 and N2O5. The use of cavity ring down spectroscopy to detect both trace gases enabled the measurements to be carried out at low mixing ratios ( 15. A value of γ(NO3)/γ(N2O5)~1.5–3 was obtained when using candle generated soot. The relative rate obtained for Saharan dust can be placed on an absolute basis using our recently determined value of γ(N2O5)=1×10−2 to give γ(NO3)=9×10−3, which is significantly smaller than the single previous value. With the present uptake coefficient, reaction of NO3 with mineral dust will generally not contribute significantly to its NO3 loss in the boundary atmosphere or to the nitration of mineral dust.

3 citations

Journal ArticleDOI
TL;DR: In this paper , the authors investigated the heterogeneous kinetics of the OH-initiated degradation of surface-bound fenthion and parathion using a flow reactor, and they showed that OH radicals played an important role in the atmospheric degradation of Fenthion.
Abstract: Fenthion and parathion are two representative kinds of organophosphorus pesticides and widely used in agriculture. They are directly or indirectly released into the atmosphere by spraying or volatilization processes. However, their heterogeneous reactivity toward OH radicals has not yet been well understood. Therefore, this work investigated the heterogeneous kinetics of the OH-initiated degradation of surface-bound fenthion and parathion using a flow reactor. The results showed that OH radicals played an important role in the atmospheric degradation of fenthion and parathion. Their average rate constants were (7.20 ± 0.77) × 10−12 and (10.40 ± 0.60) × 10−12 cm3 molecule−1 s−1 at a relative humidity (RH) and temperature of 35% and 20 °C, respectively, suggesting that they have relatively short lifetimes in the atmosphere. In addition, a negative RH dependence and a positive temperature dependence of the rate constants were observed. The Arrhenius expressions of fenthion and parathion were k2 = (1.34 ± 0.48) × 10−9exp[−(1432.59 ± 105.29)/T] and k2 = (1.96 ± 1.38) × 10−9exp[−(1619.98 ± 222.02)/T], respectively, and their overall activation energy was estimated to be (11.88 ± 0.87) and (13.48 ± 1.83) kJ mol−1. The experimental results will update the kinetic data of fenthion and parathion in the atmosphere and be helpful to further understand their atmospheric transportation processes.

1 citations

References
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Journal ArticleDOI
TL;DR: In this paper, a new variant of Factor Analysis (PMF) is described, where the problem is solved in the weighted least squares sense: G and F are determined so that the Frobenius norm of E divided (element-by-element) by σ is minimized.
Abstract: A new variant ‘PMF’ of factor analysis is described. It is assumed that X is a matrix of observed data and σ is the known matrix of standard deviations of elements of X. Both X and σ are of dimensions n × m. The method solves the bilinear matrix problem X = GF + E where G is the unknown left hand factor matrix (scores) of dimensions n × p, F is the unknown right hand factor matrix (loadings) of dimensions p × m, and E is the matrix of residuals. The problem is solved in the weighted least squares sense: G and F are determined so that the Frobenius norm of E divided (element-by-element) by σ is minimized. Furthermore, the solution is constrained so that all the elements of G and F are required to be non-negative. It is shown that the solutions by PMF are usually different from any solutions produced by the customary factor analysis (FA, i.e. principal component analysis (PCA) followed by rotations). Usually PMF produces a better fit to the data than FA. Also, the result of PF is guaranteed to be non-negative, while the result of FA often cannot be rotated so that all negative entries would be eliminated. Different possible application areas of the new method are briefly discussed. In environmental data, the error estimates of data can be widely varying and non-negativity is often an essential feature of the underlying models. Thus it is concluded that PMF is better suited than FA or PCA in many environmental applications. Examples of successful applications of PMF are shown in companion papers.

4,797 citations


"OH-initiated heterogeneous oxidatio..." refers background in this paper

  • ...05 (Paatero, 1997; Paatero and Tapper, 1994) to separate the signals of TBEP, CA, and their corresponding oxidation products....

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Journal ArticleDOI
11 Dec 2009-Science
TL;DR: A unifying model framework describing the atmospheric evolution of OA that is constrained by high–time-resolution measurements of its composition, volatility, and oxidation state is presented, which can serve as a basis for improving parameterizations in regional and global models.
Abstract: Organic aerosol (OA) particles affect climate forcing and human health, but their sources and evolution remain poorly characterized. We present a unifying model framework describing the atmospheric evolution of OA that is constrained by high-time-resolution measurements of its composition, volatility, and oxidation state. OA and OA precursor gases evolve by becoming increasingly oxidized, less volatile, and more hygroscopic, leading to the formation of oxygenated organic aerosol (OOA), with concentrations comparable to those of sulfate aerosol throughout the Northern Hemisphere. Our model framework captures the dynamic aging behavior observed in both the atmosphere and laboratory: It can serve as a basis for improving parameterizations in regional and global models.

3,104 citations


Additional excerpts

  • ...…of mixing state on TBEP oxidation (Exp. III)10 in the ambient atmosphere, particles are often internally or externally mixed with other components (Jimenez et al., 2009), and it is well recognized that the mixing state or morphology of particles plays an important role in heterogeneous reaction…...

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Journal ArticleDOI
TL;DR: In this article, the authors reviewed existing knowledge with regard to organic aerosol (OA) of importance for global climate modelling and defined critical gaps needed to reduce the involved uncertainties, and synthesized the information to provide a continuous analysis of the flow from the emitted material to the atmosphere up to the point of the climate impact of the produced organic aerosols.
Abstract: The present paper reviews existing knowledge with regard to Organic Aerosol (OA) of importance for global climate modelling and defines critical gaps needed to reduce the involved uncertainties. All pieces required for the representation of OA in a global climate model are sketched out with special attention to Secondary Organic Aerosol (SOA): The emission estimates of primary carbonaceous particles and SOA precursor gases are summarized. The up-to-date understanding of the chemical formation and transformation of condensable organic material is outlined. Knowledge on the hygroscopicity of OA and measurements of optical properties of the organic aerosol constituents are summarized. The mechanisms of interactions of OA with clouds and dry and wet removal processes parameterisations in global models are outlined. This information is synthesized to provide a continuous analysis of the flow from the emitted material to the atmosphere up to the point of the climate impact of the produced organic aerosol. The sources of uncertainties at each step of this process are highlighted as areas that require further studies.

2,863 citations

Journal ArticleDOI
TL;DR: In this paper, the use of PFRs as potential substitutes for brominated flame retardants (BFRs) has been discussed and a number of potential alternatives for BFRs have been proposed.

1,953 citations


Additional excerpts

  • ...The vapor pressure of TBEP at 298 K is reported to range from 2.5×10−8 to 1.23×10−6 Torr (Veen and Boer, 2012; Verbruggen et al., 2005; Bergman et al., 2012; Brommer15 et al., 2014)....

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Journal ArticleDOI
TL;DR: The current state of knowledge, major open questions, and research perspectives on the properties and interactions of atmospheric aerosols and their effects on climate and human health are outlined.
Abstract: Aerosols are of central importance for atmospheric chemistry and physics, the biosphere, climate, and public health. The airborne solid and liquid particles in the nanometer to micrometer size range influence the energy balance of the Earth, the hydrological cycle, atmospheric circulation, and the abundance of greenhouse and reactive trace gases. Moreover, they play important roles in the reproduction of biological organisms and can cause or enhance diseases. The primary parameters that determine the environmental and health effects of aerosol particles are their concentration, size, structure, and chemical composition. These parameters, however, are spatially and temporally highly variable. The quantification and identification of biological particles and carbonaceous components of fine particulate matter in the air (organic compounds and black or elemental carbon, respectively) represent demanding analytical challenges. This Review outlines the current state of knowledge, major open questions, and research perspectives on the properties and interactions of atmospheric aerosols and their effects on climate and human health.

1,868 citations


Additional excerpts

  • ...The effects of fine particles on the atmosphere, climate, and public health are among the central topics in current environmental research (Pöschl, 2005)....

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  • ...These effects are closely related to the particle size, morphology, and composition (Pöschl, 2005; Kolb25 and Worsnop, 2012)....

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