Abstract  A single-cylinder engine diesel exhaust exposure system was constructed to conduct laboratory health effects studies. The single-cylinder engine was selected to provide a cost-effective and easy-to-operate biological exposure system as an alternative to larger engines operated on chassis or test stand dynamometers. The engine was a 5500-watt diesel generator operated at load by connection to a bank of 11 500 watt light sources. The engine was isolated from the rodent and cell exposure chambers to ameliorate excessive noise and heat in the exposure room. Exhaust was diluted approximately 100: 1 and routed to a 1 m(3) flow-through exposure chamber where the exhaust composition was assessed in detail. Measurements included particle mass, particle size distribution ( based on both number and mass), carbon monoxide, nitrogen oxides, particle carbon ( organic and elemental), particle sulfate/nitrate, metals, total and speciated volatile hydrocarbons, and speciated semivolatile and particle-phase polycyclic aromatic hydrocarbons. The exhaust composition was compared with published diesel exhaust compositions and that from a 2000 Model Cummins 5.9L ISB engine, which was operated on a variable duty cycle on a dynamometer using the same fuel and lube oil as the single-cylinder engine. The exhaust composition from the single-cylinder engine was consistent with "typical" diesel exhaust and the larger on-road engine. It yielded particle mass with a mass median diameter of similar to 0.1 mum that was composed of similar to70% elemental carbon, similar to35% organic carbon,similar to 4-5% sulfate/nitrate, and small amounts of metals. The volatile and speciated organic/inorganic gases were in the range of literature values, with specific characteristics of low particle bound aromatic compounds and higher amounts of volatile and oxygenated organics. Based on this evaluation, the single-cylinder engine and exhaust dilution system described here generates emissions that should be useful for studying health hazards that pertain to emissions from a broad range of diesel engines.

Abstract  The dose effect of cyanidin interaction with lead ions in maize seedling roots was established using reflectance spectroscopy and colorimetry. It was demonstrated basing on the regression analysis that changes of spectral parameters were related to enhanced complex formation when the metal concentration increases.

Abstract  Simulative lead polluted wastes which containing unpolluted soil, household waste, straw, bran and lead nitrate were prepared. Inoculation of white-rot fungi and uninoculation in composting of lead-contaminated waste were studied. Change of chemical factor, biological parameter and biological toxicity analyses with time during the composting process were determined to study effect of heavy metal on composting process and probability of application of white-rot fungi in composting of metal-contaminated waste. The results show the composting of lead-contaminated waste inoculated white-rot fungi could be successfully processed, which lead to the reduction of the bioavailability of Pb in compost and alleviate the potential harm from heavy metal. Under this composting process, for the final compost, pH, water-soluble organic carbon/nitrogen, volatile solid, lignin and coarse fibre remained reached 7.9, 4.01, 36.1%, 22.4g, 30.1g, respectively. In addition, 63.38% of Pb in residual fraction and 0% of Pb in soluble-exchangeable fraction were found in final compost, and the germination index of final compost reached 121%.

Abstract  A campaign of sampling total suspended particles (TSP) and fine particles (PM(2.5)) in Beijing from 2001 to 2004 were carried out to investigate the mineral aerosol and its impact on urban pollution aerosols, mainly sulfate, nitrate, and ammonium. In urban Beijing, mineral aerosol accounted for 32-67% of TSP, 10-70% of PM(2.5) in normal four seasons, and as high as 74% of TSP and 90% of PM(2.5) in dust storm period. The sources from outside Beijing accounted for 62% of the total mineral aerosols in TSP, and 76% in PM(2.5) in spring, 69% and 45% in TSP and PM(2.5), respectively, in winter, similar to 20% of both TSP and PM2.5 in summer and autumn; and it reached as high as 97% of TSP in dust storm days. Mineral aerosol has an important positive influence on formations of sulfate, nitrate, and ammonium, as there was a positive correlation between sulfate/nitrate/ammonium and mineral aerosol under appropriate meteorological conditions. Sulfate, and ammonium mainly existed in fine particles, PM(2.5), Sulfate might mostly derive from the formation on the pathways of the long-range transport by the reactions of their precursors SO(2) on the surfaces of dust particles, while nitrate was mostly derived by the homogeneous reaction and the neutralization of their precursors NO(2) on surfaces of mineral aerosol. Nitrate and ammonium mostly derived from the local pollution sources. (C) 2007 Elsevier Ltd. All rights reserved.

Abstract  Macroscopic sorption studiesndicated that Pb sorption capacity wasndependentf pHver the pH range 5-7, while sorption as a functionf reaction time up to two weeks for systems with no bulk precipitate phases showed continuous Pb uptakenolomite. This could beue toiffusionf Pbnto the microporesfolomite as well as anncreasen surface sites caused by particle size reductionuring suspension mixing. Normalized XANES spectra for systems undersaturated with respect to Pb carbonate precipitates resembled the spectrumf Pb4(OH)4(4+), suggesting that Pbs mainly coordinated toolomite as annner-sphere surface complex. On thether hand, the XANES spectrum for 10(-3) M Pb at 1 atm CO2(g)n a 2 M Mg(NO3)2 background electrolyte solution resembled thatf cerussite, while a sample at 5 x 10(-4) M Pbn equilibrium with air and 2 M Mg(NO3)2 resembled thatf hydrocerussite. EXAFS analysesf sorption samplesn chloride solutions showed that there werenly first-shell contributions under 1 atm CO2(g), while higher shell contributions from Ca/Mg were seen at 10(-3.42) atm CO2(g). On thether hand, EXAFS samples preparedn nitrate solutions showed noticeableifferencesn speciation underifferent reaction conditions-fromuter-sphere surface complexes at low Pb concentrations and pH, tonner-sphere surface complexes at moderate Pb concentrations and neutral pH, to the formationf Pb carbonate precipitates at the highest Pb loadings.

Abstract  A study was carriedutn the residue levelf major concern pollutants (PAHs, PCBs and HMs) and the assessmentf their genotoxicityn soilsbtained from Shenyang, northeastf China which had been subjected to wastewaterrrigation for more than 40 years. Topsoils (0-20cm)n paddy fields were sampled along the upper, middle and lower reachesf the wastewaterisposal channel. Sixteen USEPA PAHs wereetermined by High Performance Liquid Chromatography (HPLC) with fluorescenceetector, eight PCBs wereetected by Gas Chromatography (GC) with electron captureetector, and six heavy metals (Cd, Cu, Pb, Zn, Ni, and Cr) were measured by Atomic Absorption Spectrophotometer (AAS). The genotoxicity effectf soils was examined by Vicia faba micronucleus (MN) test. Archived soils that had undergone a similar historyf wastewaterrrigation provided by Technical Universityf Berlin, Germany were subjected to analysisf the above pollutants and Vicia faba/MN test for comparison. Resultsndicated elevated residuesf the studied pollutants (PAHs, especially benzo (a) pyrene, the eight PCB congeners and heavy metals)n both tested and archived soils. The MN frequencies were 2.2-48.4 times higher compared with the control. However, there was no correlation between the MN frequencies and the concentrationf pollutantsetected. Thisnvestigation suggested a potential ecological risk even with a lower levelf residual pollutantsn soil matrix after long-term wastewaterrrigation.

Abstract  Propertiesf verticalistributionf soil near water bodies are vary considerably from thosef land and may greatly affect the transportationf heavy metalsn wetlands. Verticalistributionsf heavy metals (Cr, Cd, Cu, Pb, and Zn)n the soilf aquatic-terrestrial ecotone (ATE)f Lake Taihu, China, andn wetland plant tissues were studied. Generally, concentrationsf heavy metalsecreased withncreasingepthn the top 40-cm cores and thenncreased slightly withncreasingepth. Thisnvestigationndicated that concentrationsf Cd, Cr, Pb, and Zn exceeded the geochemical background valuesn the Taihu Lake area. Concentrationsf Cd at allepth soil columns exceeded the Environment Quality Standard for Soilsf China. Correlation analysis showed that concentrationsf Zn, Cr, Cd, and Pb correlated significantly withne another, suggesting that they had the samerigin. The concentrationf Cu was negatively correlated with root biomass, which may explain the lower concentrationf coppern the soil cores. Theominant plantsf the wetland were Phragmites australis and Ludwigia prostrata, and heavy metal accumulated primarilyn the root tissue. The generalrder was root > rhizome > stem > leaf, whereasn L. prostrata, leaf was the main tissue for Cr accumulation. Both P. australis and L. prostrata had the highest concentration factor (CF) to Cu, and CF was 20.3 and 15.8, respectively. Aquatic-terrestrial ecotone plants are more effectiven controlling Cu pollution thanther heavy metals. This will be very significant for ATE reestablishment near Cu-polluted sites.

Abstract  Measurement of fine particulate and gas-phase species during the New Year's fireworks 2005 in Mainz, Germany is investigated. The chemical composition and chemically resolved size distribution of fine aerosol particles are measured at high time resolution with a time-of-flight aerosol mass spectrometer (TOF-AMS). In addition, particle number concentrations and trace gas concentrations are measured using a condensation particle counter (CPC) and a proton transfer reaction mass spectrometer (PTR-MS). The main non-refractory components of the firework aerosol are potassium, sulfate, total organics, and chloride. Increased trace gas mixing ratios of methanol, acetonitrile, acetone and acetaldehyde are observed. It is found that aerosol nitrate and the fireworks as well as the measured aromatic trace gases do not significantly affect ammonium concentrations.

Abstract  To comply with International agreements to improve air quality, signatory states need to reduce emissions of ammonia (NH3). Since the majority of NH3 emissions come from agriculture, measures may need to be implemented by the farming industry. Member states of the EU will, by 2010, require large pig and poultry production units to reduce NH3 emissions to comply with the integrated pollution prevention and control directive (IPPC). The NARSES model uses a mass-flow method to estimate NH3 emission from UK agriculture and to identify the most cost-effective means of reducing NH3 emissions. Model runs were carried out to assess the likely impact of the IPPC Directive on UK NH3 emissions and the sensitivity of model output to input data on the costs and abatement efficiencies of proposed abatement measures. The impact of the IPPC Directive is likely to be small, offering a reduction of c. 8700t, 3.5% of total UK agricultural NH3 emissions. Even large (30%) changes in our estimates of cost or changes of 10% in our estimates of abatement efficiency will make little difference to the ranking of abatement techniques according to cost-effectiveness. The most cost-effective reductions may be achieved by replacing urea fertilizer with ammonium nitrate, immediate incorporation of manures and slurries to tillage land by discs, storing all FYM and poultry manures before spreading to land and applying slurries to grassland by trailing shoe. (c) 2006 Published by Elsevier Ltd.

Abstract  A winter PM2.5 episode that achieved a maximum 24-h average of 138 mug m(-3) at the Fresno Supersite in California's San Joaquin Valley between 2 and 12 January, 2000 is examined using 5-min to 1-h continuous measurements of mass, nitrate, black carbon, particle-bound PAH, and meteorological measurements. Every day PM2.5 sampling showed that many episodes. including this one, are missed by commonly applied sixth-day monitoring, even though quarterly averages and numbers of US air quality standard exceedances are adequately estimated. Simultaneous measurements at satellite sites show that the Fresno Supersite represented PM2.5 within the city, and that half or more of the urban concentrations were present at distant, non-urban locations unaffected by local sources. Most of the primary particles accumulated during early morning and nighttime, decreasing when 'surface temperatures increased and the shallow radiation inversion coupled to a valleywide layer. When this coupling occurred, nitrate levels increased rapidly over a 10-30 min period as black carbon and gaseous concentrations dropped. This is consistent with a conceptual model in which secondary aerosol forms above the surface layer and is effectively decoupled from the surface for all but the late-morning and early afternoon period. Primary pollutants, such as organic and black carbon. accumulate within the shallow surface layer in urban areas where wood burning and vehicle exhaust emissions are high. Such a model would explain why earlier studies find nitrate concentrations to be nearly the same among widely separated sites in urban areas, as winds aloft of 1 to 6 ms(-1) could easily disperse the elevated aerosol throughout the valley. (C) 2002 Elsevier Science Ltd. All rights reserved.

Abstract  Lead is a common environmental occupational toxic metal, known to have indirect oxidative effects. Considering the antioxidant properties of garlic, this study was undertaken to evaluate the therapeutic efficacy of garlic extracts in terms of normalization of altered hematological, biochemical and immunological parameters, and depletion of inorganic lead burden in blood, kidney and brain tissues. Chronic lead nitrate ingestion showed a significant decline in total erythrocyte count, total leukocyte count, hemoglobin concentration, lymphocyte and monocyte content, while neutrophil content increased in lead nitrate treated group. Pb(NO(3))(2) exposure elicited a significant escalation in thiobarbituric acid reactive substances level and depletion in reduced glutathione content and antioxidant enzymes namely, superoxide dismutase and catalase in kidney and brain. Activities of aspartate transaminase, alanine transaminase, acid phosphatase and alkaline phosphatase augmented significantly in kidney and brain of lead exposed mice. Lead nitrate treatment decreased protein content while cholesterol and lead burden increased significantly. A decrease in viability of macrophage, phagocytic index, immunoglobulin level and plaque count were the salient features observed in lead exposed animals. However, oral administration of garlic extracts to Pb(NO(3))(2) treated groups attenuated the deranged parameters to some extent. This indicates that garlic can be a protective regimen for lead toxicity.

Abstract  Economizer use in data centers is an energy efficiency strategy that could significantly limit electricity demand in this rapidly growing economic sector. Widespread economizer implementation, however, has been hindered by potential reliability concerns associated with exposing information technology equipment to particulate matter of outdoor origin. This study explores the feasibility of using economizers in data centers to save energy while controlling particle concentrations with high-quality air filtration. Physical and chemical properties of indoor and outdoor particles were analyzed at an operating northern California data center equipped with an economizer under varying levels of air filtration efficiency. Results show that when improved filtration is used in combination with an economizer, the indoor/outdoor concentration ratios for most measured particle types were similar to levels when using conventional filtration without economizers. An energy analysis of the data center reveals that, even during the summer months, chiller savings from economizer use greatly outweigh any increase in fan power associated with improved filtration. These findings indicate that economizer use combined with improved filtration could reduce data center energy demand while providing a level of protection from particles of outdoor origin similar to that observed with conventional design.

Abstract  Nitric oxide (NO) has been reported to modulate fever in the brain. However, it remains partially unclear the sites where NO exerts such a modulation. Locus Coeruleus (LC) neurons express not only nitric oxide synthase (NOS) but also soluble guanylyl cyclase (sGC). Herein we evaluated in vivo and ex vivo the putative role of the LC NO-cGMP pathway in fever. To this end, deep body temperature was measured before and after pharmacological modulations of the pathway. Moreover, nitrite/nitrate (NOx) and cGMP levels in the LC were assessed. Unanesthetized rats were microinjected within the LC with a nonselective NOS inhibitor (L-NMMA), or a NO donor (NOC12), or a sGC inhibitor (ODQ), or a cGMP analogous (8-Br-cGMP), and intraperitoneally injected with endotoxin. Inhibition of NOS or sGC before endotoxin injection significantly increased the latency to the onset of fever. During the course of fever, inhibition of NOS or sGC attenuated the febrile response, whereas microinjection of NOC12 or 8-Br-cGMP raised such a response. These findings indicate that the LC NO-cGMP pathway plays a pro-pyretic role. Furthermore, we observed a significant increase in NOx and cGMP levels, indicating that the febrile response to endotoxin is accompanied by stimulation of the NO-cGMP pathway in the LC.

Abstract  Lahore, Pakistan is an emerging megacity that is heavily polluted with high levels of particle air pollution. In this study, respirable particulate matter (PM_2.5 and PM₁₀) were collected every sixth day in Lahore from 12 January 2007 to 19 January 2008. Ambient aerosol was characterized using well-established chemical methods for mass, organic carbon (OC), elemental carbon (EC), ionic species (sulfate, nitrate, chloride, ammonium, sodium, calcium, and potassium), and organic species. The annual average concentration (+/-one standard deviation) of PM_2.5 was 194 +/- 94 μg m⁻³ and PM₁₀ was 336 +/- 135 μg m⁻³. Coarse aerosol (PM_10−2.5) was dominated by crustal sources like dust (74 +/- 16%, annual average +/- one standard deviation), whereas fine particles were dominated by carbonaceous aerosol (organic matter and elemental carbon, 61 +/- 17%). Organic tracer species were used to identify sources of PM_2.5 OC and chemical mass balance (CMB) modeling was used to estimate relative source contributions. On an annual basis, non-catalyzed motor vehicles accounted for more than half of primary OC (53 +/- 19%). Lesser sources included biomass burning (10 +/- 5%) and the combined source of diesel engines and residual fuel oil combustion (6 +/- 2%). Secondary organic aerosol (SOA) was an important contributor to ambient OC, particularly during the winter when secondary processing of aerosol species during fog episodes was expected. Coal combustion alone contributed a small percentage of organic aerosol (1.9 +/- 0.3%), but showed strong linear correlation with unidentified sources of OC that contributed more significantly (27 +/- 16%). Brick kilns, where coal and other low quality fuels are burned together, are suggested as the most probable origins of unapportioned OC. The chemical profiling of emissions from brick kilns and other sources unique to Lahore would contribute to a better understanding of OC sources in this megacity. [Copyright &y& Elsevier]

Abstract  Dietary N-nitroso compounds are carcinogens synthesized during food processing from two main classes of precursors, oxides of nitrogen and amines or amides. Quantification of the dietary intake of N-nitroso compounds is significant to human cancers, including those of the stomach and upper gastro-intestinal tract, colon, and brain. Previous studies investigating these cancers primarily used proxy estimates of N-nitroso intake and not a full and complete database. In this report, we describe the development of a database to be used in conjunction with a food frequency questionnaire (FFQ) or twenty-four hour dietary records. Published analytical data for N-nitroso compounds were compiled and evaluated for inclusion in the database. The final database consisted of 23 different N-nitroso compounds for 500 foods from 39 different food subgroups. Next, database foods were matched to foods in a standard FFQ by imputation, or calculated value, or assumed zero. Using the FFQ modified with N-nitroso values, we evaluated the ability to compute N-nitroso intakes for a sample of healthy control subjects of cancer epidemiological studies. N-nitroso content of food items ranged from <0.01mug/100 g. to 142 mug/100 g and the richest sources were sausage, smoked meats, bacon, and luncheon meats. The database is useful to quantify N-nitroso intake for observational and epidemiological studies.

Abstract  Bromine and iodine in atmospheric particles or coal can cause environmental problems such as destruction of ozone in the atmosphere; therefore, the presence of these compounds has recently received increased attention. Here, a rapid and reliable method for the simultaneous determination of total bromine and iodine using ICP-MS analysis is described. Samples were dissolved in mixtures of 5 mL of HNO(3) and 2 mL of H(2)O(2) in a high pressure microwave digester. The solution was then oxidized by per-sulfate (Na(2)S(2)O(8)) in addition to a small amount of silver nitrate, after which the total bromine and iodine were measured simultaneously by ICP-MS. The signal memory effects of bromine and iodine during analysis were effectively decreased by washing with a new mixture agent (2% alcohol acidic solution, pH 1-2 adjusted with HCl). The detection limits for bromine and iodine using this method were about 3.2 microg L(-1) and 1.1 microg L(-1), respectively. Additionally, the spike recoveries were between 78.7% and 121% for bromine and iodine analysis, while the relative standard deviations ranged from 4.3% to 9.7%, and from 1.5% to 3.4% for bromine and iodine, respectively. The results of this study indicate that the method described here is suitable for the analysis of micro-amounts of bromine and iodine in atmospheric particles and coal samples. (c) 2009 Elsevier B.V. All rights reserved.

Abstract  INTRODUCTION: Small bowel transplantation provides a potentially life-saving treatment of severe intestinal failure. Lack of a noninvasive marker of disease makes diagnosis of rejection dependent on frequent endoscopy and biopsy. We hypothesized that increased plasma nitrite and nitrate (NOx) levels measured after small bowel transplant would be associated with abnormal final pathology. METHODS: We measured total plasma NOx levels (the stable end products of the L-arginine/nitric oxide biosynthetic pathway) in 120 prospectively collected samples taken from 27 patients after small bowel transplantation. We used immunohistochemistry to detect inducible nitric oxide synthetase expression in 19 tissue biopsies from 9 patients. RESULTS: We found NOx concentrations to be statistically different between pathologic categories (e.g., normal, mild, moderate, and severe rejections, nonspecific enteritis), although there was sufficient overlap to prompt caution clinically. After establishing from the dataset a "normal" plasma NOx level of 50 microM, we found that combined assessment of plasma NOx levels and clinical suspicion of pathology could accurately predict which patients were histologically normal and those requiring further evaluation with endoscopy and biopsy. CONCLUSIONS: We conclude that serum NOx levels are significantly associated with small bowel pathology after transplant, although not specifically enough with rejection to be relied on for clinical discrimination.

Abstract  Halogen atoms and oxides are highly reactive and can profoundly affect atmospheric composition. Chlorine atoms can decrease the lifetimes of gaseous elemental mercury(1) and hydrocarbons such as the greenhouse gas methane(2). Chlorine atoms also influence cycles that catalytically destroy or produce tropospheric ozone(3), a greenhouse gas potentially toxic to plant and animal life. Conversion of inorganic chloride into gaseous chlorine atom precursors within the troposphere is generally considered a coastal or marine air phenomenon(4). Here we report mid-continental observations of the chlorine atom precursor nitryl chloride at a distance of 1,400km from the nearest coastline. We observe persistent and significant nitryl chloride production relative to the consumption of its nitrogen oxide precursors. Comparison of these findings to model predictions based on aerosol and precipitation composition data from long-term monitoring networks suggests nitryl chloride production in the contiguous USA alone is at a level similar to previous global estimates for coastal and marine regions(5). We also suggest that a significant fraction of tropospheric chlorine atoms(6) may arise directly from anthropogenic pollutants.

Abstract  A series of modeling approaches for the description of the dynamic behavior of secondary organic aerosol (SOA) components and their interactions with inorganics is presented. The models employ a lumped species approach based on available smog chamber studies and the UNIquac Functional-group Activity Coefficient (UNIFAC) method to estimate SOA water absorption. The additional water due to SOA species can change the partitioning behavior of the semi-volatile inorganics. Primary organic particles significantly influence the SOA partitioning between gas and aerosol phases. The SOA size distribution predicted by a bulk equilibrium approach is biased toward smaller sizes compared with that of a fully dynamic model. An improved weighting scheme for the bulk equilibrium approach is proposed in this work and is shown to minimize this discrepancy. SOA is predicted to increase the total aerosol water in Southern California by 2-13% depending on conditions. However, the effect of SOA water absorption on aerosol nitrate is insignificant for all the cases studied in Southern California. (C) 2003 Elsevier Ltd. All rights reserved.

Abstract  A comprehensive acid deposition model was used to calculate an annual amount of acid deposition in North East Asia as well as to derive a source-receptor relation. The model results for gaseous SO2 and o(3) agree very well with measurements, but the model under-estimated NO2 concentrations. Similarly, the model estimates the sulfate in rain waters quite well but under-estimates nitrate in the rain waters. The correlation coefficients for the spatial distributions of the calculated and measured annual mean concentrations were 0.97, 0.63 and 0.90 for the gaseous SO2, O-3, and NO2. One-third of SO2 emitted in North East Asia was calculated to be advected out mostly in the form of sulfate. The amount removed by dry deposition is comparable to that removed by wet deposition for sulfur but it is 40% larger than that by wet deposition for nitrogen. The source-receptor relations derived by the counter-species method show that the wet deposition is more influenced by the long-range transport than the dry deposition. Furthermore, the long-range transport contribution was calculated to be the lowest in the summer and the highest in the winter. (C) 2003 Elsevier Science Ltd. All rights reserved.

Abstract  The future changes of acid deposition characteristics in North East Asia are investigated by comparing the simulation results of the comprehensive acid deposition model for the year 1996 with those for the year 2020. The SO2 emissions are estimated to increase less than 20% until 2020 in most of the North East Asian regions, whereas much greater emission increases are expected for NOx. The calculated future surface concentrations of the primary pollutants such as SO2 and NOx show a linear response to their future emission increases while being smoothed by the transport effects. In contrast, the calculated future surface concentrations of the secondary pollutants such as sulfate and HNO3 respond non-linearly to the future emission changes of the corresponding primary pollutants.

The ratio of future wet deposition to dry deposition is calculated to decrease for sulfate but to increase for nitrate, implying that the importance of dry deposition will increase for sulfate but decrease for nitrate in 2020 compared to 1996. In addition, the S/N ratio of the wet and dry deposition is predicted to decrease substantially in 2020 due to the aggressive control policies on SO2 emissions expected in the region. Finally, the long-range transport from China to Korea is estimated to be less important for sulfur-containing acids but more important for nitrogen-containing acids in 2020 compared to 1996. (C) 2003 Elsevier Science Ltd. All rights reserved.

Abstract  Spokane, WA is prone to frequent particulate pollution episodes due to dust storms, biomass burning, and periods of stagnant meteorological conditions. Spokane is the location of a long-term study examining the association between health effects and chemical or physical constituents of particulate pollution. Positive matrix factorization (PMF) was used to deduce the sources Of PM2.5 (particulate matter less than or equal to2.5 mum in aerodynamic diameter) at a residential site in Spokane from 1995 through 1997. A total of 16 elements in 945 daily PM2.5 samples were measured. The PMF results indicated that seven sources independently contribute to the observed PM2.5 mass: vegetative burning (44%), sulfate aerosol (19%), motor vehicle (11%), nitrate aerosol (9%), airborne soil (9%), chlorine-rich source (6%) and metal processing (3%). Conditional probability functions were computed using surface wind data and the PMF deduced mass contributions from each source and were used to identify local point sources. Concurrently measured carbon monoxide and nitrogen oxides were correlated with the PM2.5 from both motor vehicles and vegetative burning. (C) 2003 Elsevier Science B.V. All rights reserved.

Abstract  A thermodynamic model, the Gibbs Free-Energy Minimization model (GFEMN), was used to simulate the partitioning of PM2.5 nitrate aerosol and nitric acid using highly time-resolved inorganic measurements collected at the Pittsburgh Air Quality Study during July 2001 and January 2002. Model results were evaluated using independent, high time resolution measurements of aerosol nitrate. The mean observed concentration in July was 0.6 μg/m3 and 2.1 μg/m3 in January. Model predictions were in agreement with the observations within 0.5 μg/m3 on average, with measurement uncertainties often accounting for these discrepancies. The simulations were run assuming particles were liquid in July for all relative humidities (RHs) and solid below 60% RH in January. For both seasons the assumed physical state did not influence considerably the overall agreement with observations. The assumption of particle mixing state did appear to influence model error; however, assuming that particles were externally mixed during low RH periods in July improved agreement significantly. The exceptional sensitivity of predicted aerosol nitrate to ammonia in western Pennsylvania suggests that reductions in PM2.5 may be assisted by reductions in ammonia emissions.

Abstract  The extensive thermodynamic and optical properties recently reported [Tang and Munkelwitz, 1994a] for sulfate and nitrate solution droplets are incorporated into a visibility model for computing light scattering by hygroscopic aerosols. The following aerosol systems are considered: NH4HSO4, (NH4)2SO4, (NH4)3H(SO4), NaHSO4, Na2SO4, NH4NO3, and NaNO3. In addition, H2SO4 and NaCl are included to represent freshly formed sulfate and background sea-salt aerosols, respectively. Scattering coefficients, based on 1 ?g dry salt per cubic meter of air, are calculated as a function of relative humidity for aerosols of various chemical compositions and lognormal size distributions. For a given size distribution the light scattered by aerosol particles per unit dry-salt mass concentration is only weakly dependent on chemical constituents of the hygroscopic sulfate and nitrate aerosols. Sulfuric acid and sodium chloride aerosols, however, are exceptions and scatter light more efficiently than all other inorganic salt aerosols considered in this study. Both internal and external mixtures exhibit similar light-scattering properties. Thus for common sulfate and nitrate aerosols, since the chemical effect is outweighed by the size effect, it follows that observed light scattering by the ambient aerosol can be approximated, within practical measurement uncertainties, by assuming the aerosol being an external mixture. This has a definite advantage for either visibility degradation or climatic impact modeling calculations, because relevant data are now available for external mixtures but only very scarce for internal mixtures.