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The morphological transformation of soot particles via condensation of low-volatility materials constitutes a dominant atmospheric process with serious implications for the optical and hygroscopic properties, as well as atmospheric lifetime of the soot. We consider the morphological transformation of soot aggregates under the influence of condensation of vapors of sulfuric acid, and/or limonene ozonolysis products. This influence was systematically investigated using a Differential Mobility Analyzer coupled with an Aerosol Particle Mass Analyzer (DMA-APM) and the Tandem DMA techniques integrated with a laminar flow-tube system. We hypothesize that the morphology transformation of soot results (in general) from a two-step process, i.e., (i) filling of void space within the aggregate and (ii) growth of the particle diameter. Initially, the transformation was dominated by the filling process followed by growth, which led to the accumulation of sufficient material that exerted surface forces, which eventually facilitated further filling. The filling of void space was constrained by the initial morphology of the fresh soot as well as the nature and the amount of condensed material. This process continued in several sequential steps until all void space within the soot aggregate was filled. And then "growth" of a spherical particle continued as long as vapors condensed on it. We developed a framework for quantifying the microphysical transformation of soot upon the condensation of various materials. This framework used experimental data and the hypothesis of "ideal sphere growth" and void filling to quantify the distribution of condensed materials in the complementary filling and growth processes. Using this framework, we quantified the percentage of material consumed by these processes at each step of the transformation. For the largest coating experiments, 6, 10, 24, and 58% of condensed material went to filling process, while 94, 90, 76, and 42% of condensed material went to growth process for 75, 100, 150, and 200 nm soot particles, respectively. We also used the framework to estimate the fraction of internal voids and open voids. This information was then used to estimate the volume-equivalent diameter of the soot aggregate containing internal voids and to calculate the dynamic shape factor, accounting for internal voids. The dynamic shape factor estimated based on the traditional assumption (of no internal voids) differed significantly from the value obtained in this study. Internal voids are accounted for in the experimentally derived dynamic shape factor determined in the present study. In fact, the dynamic shape factor adjusted for internal voids was close to 1 for the fresh soot particles considered in this study, indicating the particles were largely spherical. The effective density was strongly correlated with the morphological transformation responses to the condensed material on the soot particle, and the resultant effective density was determined by the (i) nature of the condensed material and (ii) morphology and size of the fresh soot. In this work we quantitatively tracked in situ microphysical changes in soot morphology, providing details of both fresh and coated soot particles at each step of the transformation. This framework can be applied to model development with significant implications for quantifying the morphological transformation (from the viewpoint of hygroscopic and optical properties) of soot in the atmosphere. [ABSTRACT FROM AUTHOR]

An operational chemical ionization mass spectrometer (CIMS) for hydroxyl radical (OH) and sulfuric acid (H2SO4) concentration measurements was adapted to include observations of OH reactivity, which is the inverse of OH lifetime, for long-term monitoring at the Global Atmosphere Watch (GAW) site Hohenpeissenberg (MOHp), Germany. OH measurement using CIMS is achieved by reacting OH with SO2, leading to the production of H2SO4, which is then detected. The adaptation for OH reactivity consists of the implementation of a second SO2 injection, at a fixed point further down flow in the sample tube to detect the OH decay caused by reactions with OH reactants present in the sample. The method can measure OH reactivity from less than 1 to 40 s1 with the upper limit due to the fixed positioning of the second SO2 injection. To determine OH reactivity from OH concentration measurements, the reaction time between the two titration zones and OH wall losses in the sample tube need to be determined accurately through OH reactivity calibration. Potential measurement artefacts as a result of HOx recycling in the presence of NO have to be considered. Therefore, NO contamination from gases used in instrument operation must be minimized and ambient NO must be measured concurrently to determine the measurement error. This CIMS system is shown here to perform very well for OH reactivity below 15 s1 and NO concentrations below 4 ppb, both values that are rarely exceeded at the MOHp site. Thus when deployed in suitable chemical environments, this method can provide valuable continuous long-term measurements of OH reactivity. The characterization utilizes results from chamber, laboratory and modelling studies and includes the discussion and quantification of sources of uncertainties. [ABSTRACT FROM AUTHOR]

We investigate the mixed sulfuric acid-water clusters in a molecular beam experiment with electron attachment and negative ion mass spectrometry and complement the experiment by density functional theory (DFT) calculations. The microhydration of (H2SO4)m(H2O)n clusters is controlled by the expansion conditions, and the electron attachment yields the main cluster ion series (H2SO4/m(H2O)nHSO-4 and (H2O)nH2SO-4. The mass spectra provide an experimental evidence for the onset of the ionic dissociation of sulfuric acid and ion-pair (HSO4- ...H3O+)formation in the neutral H2SO4(H2O)n clusters with n 5 water molecules, in excellent agreement with the theoretical predictions. In the clusters with two sulfuric acid molecules (H2SO4/2(H2O)n this process starts as early as n 2 water molecules. The (H2SO4/m(H2O)nHSO-4 clusters are formed after the dissociative electron attachment to the clusters containing the (HSO-4...H3O+)ion-pair structure, which leads to the electron recombination with the H3O+ moiety generating H2O molecule and the H-atom dissociation from the cluster. The (H2O)nH2SO-4 cluster ions point to an efficient caging of the H atom by the surrounding water molecules. The electron-energy dependencies exhibit an efficient electron attachment at low electron energies below 3 eV, and no resonances above this energy, for all the measured mass peaks. This shows that in the atmospheric chemistry only the low-energy electrons can be efficiently captured by the sulfuric acid-water clusters and converted into the negative ions. Possible atmospheric consequences of the acidic dissociation in the clusters and the electron attachment to the sulfuric acid-water aerosols are discussed. [ABSTRACT FROM AUTHOR]

ABSTRACT BACKGROUND Owing to the visible plume and secondary aerosol formation, the emissions of sulfuric acid mist from coal-fired power plants have attracted increasing attention. To provide more information for the control of sulfuric acid mist emission, investigations were made of the formation and removal characteristics of sulfuric acid mist in a wet flue gas desulfurization system. RESULTS The results showed that large numbers of sulfuric acid droplets with sizes less than 0.1 µm were generated via homogenous nucleation. With higher inlet SO3 concentrations, the fine particle concentration after desulfurization was increased. Increases in the liquid-gas ratio and the inlet fly ash concentration and decreases in the inlet flue gas temperature improved the sulfuric acid mist removal efficiency. The wet flue gas desulfurization ( WFGD) system with double scrubbers achieved higher sulfuric acid mist removal efficiency than the WFGD system with a single scrubber. CONCLUSION The sulfuric acid mist droplets created via homogenous nucleation were mainly in the submicron range, and their removal efficiencies in the WFGD system were influenced by the desulfurization operating parameters. The WFGD system with double scrubbers achieved higher removal efficiency. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The objective of this study was to obtain an indicator of labile nitrogen (N) through a cost- and time-saving procedure by evaluating the relationships among potentially mineralizable N (N0), particulate organic matter N (POM-N) and soil organic N extracted through partial soil digestion with different concentrations of sulfuric acid (H2SO4). Soil sampling (0–20 cm) was from nine fields under no-tillage. The N0and POM-N were determined by long-term aerobic incubation and soil physical fractionation, respectively. A simple chemical method was developed by soil digestion at 100°C for 4 h with different concentrations of H2SO4(0.1, 0.5, 1, 6, 12, and 24 mol L−1). All acid concentrations showed significant relationships with N0as POM-N; however, the best prediction was resulted for 0.5 mol L−1(R2 = 0.90–0.94, respectively), thus using this methodology as soil labile N indicator. This method would optimize N0and POM-N estimation in short term and at a low cost. [ABSTRACT FROM AUTHOR]

Biofilters are used for the conversion of odorous hydrogen sulphide to odourless sulphate in wastewater treatment plants under the right conditions of moisture and pH. One of the consequences of maintaining the suitable pH and moisture content is the production of large volumes of weakly acidic leachate. This paper presents a biofilter with a maximum HS elimination capacity of 16.3 g m h and removal efficiency greater than 95 % which produces small volumes (1 mL of solution L of reactor day) of sulphuric acid with a concentration greater than 5.5 M after 150 days of continuous operation. The concentrated sulphuric acid was produced by intermittently trickling a minimum amount of nutrient solution down the upflow biofilter which created a moisture and pH gradient within the biofilter resulting in an environment at the top for the bacterial conversion of HS, while sulphuric acid was accumulated at the base. Genetic diversity profiling of samples taken from different sections of the biofilter confirms that the upper sections of the biofilter had the best environment for the bacteria to convert HS to sulphate. The formation of concentrated sulphuric acid presents an opportunity for the recovery of sulphur from the waste stream as a usable product. [ABSTRACT FROM AUTHOR]

The particle formation scheme within PMCAMx-UF, a three-dimensional chemical transport model, was updated with particle formation rates for the ternary H2SO4- NH3-H2O pathway simulated by the Atmospheric Cluster Dynamics Code (ACDC) using quantum chemical input data. The model was applied over Europe for May 2008, during which the EUCAARI-LONGREX (European Aerosol Cloud Climate and Air Quality Interactions-Long-Range Experiment)campaign was carried out, providing aircraft vertical profiles of aerosol number concentrations. The updated model reproduces the observed number concentrations of particles larger than 4 nm within 1 order of magnitude throughout the atmospheric column. This agreement is encouraging considering the fact that no semi-empirical fitting was needed to obtain realistic particle formation rates. The cloud adjustment scheme for modifying the photolysis rate profiles within PMCAMx-UF was also updated with the TUV (Tropospheric Ultraviolet and Visible) radiativetransfer model. Results show that, although the effect of the new cloud adjustment scheme on total number concentrations is small, enhanced new-particle formation is predicted near cloudy regions. This is due to the enhanced radiation above and in the vicinity of the clouds, which in turn leads to higher production of sulfuric acid. The sensitivity of the results to including emissions from natural sources is also discussed. [ABSTRACT FROM AUTHOR]

The use of sulfur in pavement laying was developed in 1980 but it was restricted in the late 19th century due to its environmental problems and its high reactivity toward oxidation processes which give sulfuric acid products that are capable of destroying the asphalt mixture. The study involved the conversion of elemental sulfur to a more stable modified one using a combination of byproducts of olefin hydrocarbons that were obtained from petroleum fractional distillates and cyclic hydrocarbon bituminous residue at 145 °C. The changes in the structural characteristics and morphology of prepared modified sulfur were studied using XRD and SEM respectively. Also DSC curves help us to elucidate the changes in sulfur phases from α-orthorhombic to β-mono clinic structure. The technique of nanoindentation helps us to compare the mechanical properties of modified and pure sulfur including modulus of elasticity and hardness. The hot mixture asphalt designs were prepared according to the Marshall Method in which the asphalt binder content was partially substituted with 20%, 30%, 40%, and 50% modified sulfur. The mechanical properties were measured including Marshall Stability, flow, air voids, and Marshall Stiffness. From the overall study, the results indicated that asphalt could partially be substituted with modified sulfur with no significant deleterious effect on performance and durability of hot mixed asphalt. [ABSTRACT FROM AUTHOR]

Sulfuric acid (H2SO4), formed from oxidation of sulfur dioxide (SO2) emitted during fossil fuel combustion, is a major precursor of new airborne particles, which have well-documented detrimental effects on health, air quality, and climate. Another precursor is methanesulfonic acid (MSA), produced simultaneously with SO2 during the atmospheric oxidation of organosulfur compounds (OSCs), such as dimethyl sulfide. In the present work, a multidisciplinary approach is used to examine how contributions of H2SO4 and MSA to particle formation will change in a large coastal urban area as anthropogenic fossil fuel emissions of SO2 decline. The 3-dimensional University of California Irvine-California Institute of Technology airshed model is used to compare atmospheric concentrations of gas phase MSA, H2SO4, and SO2 under current emissions of fossil fuel-associated SO2 and a best-case futuristic scenario with zero fossil fuel sulfur emissions. Model additions include results from (i) quantum chemical calculations that clarify the previously uncertain gas phase mechanism of formation of MSA and (ii)a combination of published and experimental estimates of OSC emissions, such as those from marine, agricultural, and urban processes, which include pet waste and human breath. Results show that in the zero anthropogenic SO2 emissions case, particle formation potential from H2SO4 will drop by about two orders of magnitude compared with the current situation. However, particles will continue to be generated from the oxidation of natural and anthropogenic sources of OSCs, with contributions from MSA and H2SO4 of a similar order of magnitude. This could be particularly important in agricultural areas where there are significant sources of OSCs. [ABSTRACT FROM AUTHOR]

Sulfuric acid is an important gas influencing atmospheric new particle formation (NPF). Both the binary (H2SO4-H2O) system and the ternary system involving ammonia (H2SO4-H2O-NH3) may be important in the free troposphere. An essential step in the nucleation of aerosol particles from gas-phase precursors is the formation of a dimer, so an understanding of the thermodynamics of dimer formation over a wide range of atmospheric conditions is essential to describe NPF. We have used the CLOUD chamber to conduct nucleation experiments for these systems at temperatures from 208 to 248 K. Neutral monomer and dimer concentrations of sulfuric acid were measured using a chemical ionization mass spectrometer (CIMS). From these measurements, dimer evaporation rates in the binary system were derived for temperatures of 208 and 223 K. We compare these results to literature data from a previous study that was conducted at higher temperatures but is in good agreement with the present study. For the ternary system the formation of H2SO4 qNH3 is very likely an essential step in the formation of sulfuric acid dimers, which were measured at 210, 223, and 248 K. We estimate the thermodynamic properties (dH and dS) of the H2SO4 qNH3 cluster using a simple heuristic model and the measured data. Furthermore, we report the first measurements of large neutral sulfuric acid clusters containing as many as 10 sulfuric acid molecules for the binary system using chemical ionization-atmospheric pressure interface time-of-flight (CI-APi-TOF) mass spectrometry. [ABSTRACT FROM AUTHOR]

A high concentration of volatile nucleation mode particles (NUP) formed in the atmosphere when the exhaust cools and dilutes has hazardous health effects and it impairs the visibility in urban areas. Nucleation mechanisms in diesel exhaust are only poorly understood. We performed model studies using two sectional aerosol dynamics process models AEROFOR and MAFOR on the formation of particles in the exhaust of a diesel engine, equipped with an oxidative after-treatment system and running with low fuel sulfur content (FSC) fuel, under laboratory sampling conditions where the dilution system mimics real-world conditions. Different nucleation mechanisms were tested. Based on the measured gaseous sulfuric acid (GSA) and non-volatile core and soot particle number concentrations of the raw exhaust, the model simulations showed that the best agreement between model predictions and measurements in terms of particle number size distribution was obtained by barrier-free heteromolecular homogeneous nucleation between the GSA and a semivolatile organic vapour combined with the homogeneous nucleation of GSA alone. Major growth of the particles was predicted to occur due to the similar organic vapour at concentrations of (1-2)×1012 cm-3. The pre-existing core and soot mode concentrations had an opposite trend on the NUP formation, and the maximum NUP formation was predicted if a diesel particle filter (DPF) was used. On the other hand, the model predicted that the NUP formation ceased if the GSA concentration in the raw exhaust was less than 1010 cm-3, which was the case when biofuel was used. [ABSTRACT FROM AUTHOR]

Nucleation is a fundamental step in atmospheric new-particle formation. However, laboratory experiments on nucleation have systematically faired to demonstrate sulfuric acid particle formation rates as high as those necessary to account for ambient atmospheric concentrations, and the role of sulfuric acid in atmospheric nucleation has remained a mystery. Here, we report measurements of new particles (with diameters of approximately 1.5 nanometers) observed immediately after their formation at atmospherically relevant sulfuric acid concentrations. Furthermore, we show that correlations between measured nucleation rates and sulfuric acid concentrations suggest that freshly formed particles contain one to two sulfuric acid molecules, a number consistent with assumptions that are based on atmospheric observations. Incorporation of these findings into global models should improve the understanding of the impact of secondary particle formation on climate. 10.1126/science.1180315

Surface-to-atmosphere emissions of dimethyl sulfide (DMS) may impact global climate through the formation of gaseous sulfuric acid, which can yield secondary sulfate aerosols and contribute to new particle formation. While oceans are generally considered the dominant sources of DMS, a shortage of ecosystem observations prevents an accurate analysis of terrestrial DMS sources. Using mass spectrometry, we quantified ambient DMS mixing ratios within and above a primary rainforest ecosystem in the central Amazon Basin in real-time (2010-2011) and at high vertical resolution (2013-2014). Elevated but highly variable DMS mixing ratios were observed within the canopy, showing clear evidence of a net ecosystem source to the atmosphere during both day and night in both the dry and wet seasons. Periods of high DMS mixing ratios lasting up to 8 h (up to 160 parts per trillion (ppt)) often occurred within the canopy and near the surface during many evenings and nights. Daytime gradients showed mixing ratios (up to 80 ppt) peaking near the top of the canopy as well as near the ground following a rain event. The spatial and temporal distribution of DMS suggests that ambient levels and their potential climatic impacts are dominated by local soil and plant emissions. A soil source was confirmed by measurements of DMS emission fluxes from Amazon soils as a function of temperature and soil moisture. Furthermore, light- and temperature-dependent DMS emissions were measured from seven tropical tree species. Our study has important implications for understanding terrestrial DMS sources and their role in coupled land-atmosphere climate feedbacks. [ABSTRACT FROM AUTHOR]

Corrosion of concrete sewer pipes by sulfuric acid attack is a problem of global scope, leading to multibillion dollar losses each year. However, research is still needed to better understand the mechanisms of sulfuric acid attack on concrete and the related effects of concrete mixture design parameters. In this paper, the combined effect of wetting-drying cycles and concrete mixture design parameters including cement content, water/cement (w/c) ratio, and coarse aggregate content on the resistance of concrete to sulfuric acid was investigated. Specimens from various concrete mixtures were soaked in sulfuric acid solutions with pH of 0.3, 0.6, 1.0, 1.5, 2.0, 2.5, and 3.0. The mass loss of concrete specimens due to immersion in sulfuric acid and wetting-drying cycles was used as a measure of concrete degradation. For specimens that experienced no mass loss due to low concentration of sulfuric acid, the thickness of the gypsum layer that formed on specimens' surface was measured on thin sections using transmitted light microscopy. The effect of exposure area/volume ratio of concrete specimens on their mass loss was also investigated. Results show that the mass loss of concrete specimens immersed in sulfuric acid solutions with pH< 1.5 increased as the cement content of the mixture increased and as the w/c ratio of the mixture decreased. Moreover, the coarse aggregate content was directly proportional to the mass loss of concrete specimens immersed in sulfuric acid solutions with pH of 0.3 and 0.6, whereas its effect was minor for specimens immersed in the sulfuric acid solution with a pH of 1.0. DOI: 10.1061/(ASCE)0899-1561(2007)19:2(155) CE Database subject headings: Cement; Aggregates; Corrosion; Sewer pipes; Acids; Concrete.

Integration of extensive aerosol data collected during the past decade around the Pacific basin provides a preliminary assessment of aerosol microphysics for this region and cycling of aerosol in the troposphere. These include aircraft-based data collected as part of numerous field experiments supported by the National Aeronautics and Space Administration (NASA), the National Science Foundation (NSF), and the National Oceanic and Atmospheric Administration (NOAA) [Global Backscatter Experiment (GLOBE), First Aerosol Characterization Experiment (ACE-1), Pacific Exploratory Mission (PEM)-Tropics A and B]. Although these experiments had diverse goals, most included extensive data on aerosol size distributions, optical properties (light scattering and light absorption), and chemistry. Vertical profiles of aerosol concentration, size distribution, and light scattering were used to characterize vertical structure from 70 [degrees] S to 70 [degrees] N. The in situ data are placed in the context of meteorological regimes over the Pacific as well as processes associated with particle formation, growth, and evolution, and include dust, pollution, sea salt, sulfates, and clean cloud-processed air. The Tropics commonly have low aerosol mass but very high number concentrations in the upper free troposphere (FT) that appear to form from sulfuric acid (nucleation) in convective regions and near cloud edges. These age and subside to become effective cloud condensation nuclei (CCN) when mixed into the marine boundary layer. Fewer number but larger aerosol are more evident in the midlatitude FT These can often be internally mixed and with a nonvolatile core indicative of black carbon with volatile components (sulfate, organics, etc.). In the North Pacific springtime a combustion-derived aerosol is frequently found associated with the same meteorology that transports 'dust events.' Both constituents may dominate the scattering and absorption properties of the aerosol even though the increase in large dust particles in such events generally dominates the mass. The FT in the subtropics tends to exhibit frequent and marked transitions and mixing between these clean and continental aerosol types.

Simulations of sulfuric acid concentration and new particle formation are performed by using the zerodimensional version of the model MALTE (Model to predict new Aerosol formation in the Lower TropospherE) and measurements from the Campaign of Air Quality Research in Beijing and Surrounding areas (CAREBeijing) in 2008. Chemical reactions from the Master Chemical Mechanism version 3.2 (MCM v3.2) are used in the model. High correlation (slope=0.72, R = 0.74) between the modelled and observed sulfuric acid concentrations is found during daytime (06:00-18:00). The aerosol dynamics are simulated by the University of Helsinki Multicomponent Aerosol (UHMA) model including several nucleation mechanisms. The results indicate that the model is able to predict the on- and offset of new particle formation in an urban atmosphere in China. In addition, the number concentrations of newly formed particles in kinetic-type nucleation including homogenous homomolecular (J = K[H2SO4]²) and homogenous heteromolecular nucleation involving organic vapours (J = Khet[H2SO4][Org]) are in satisfactory agreement with the observations. However, the specific organic compounds that possibly participate in the nucleation process should be investigated in further studies. For the particle growth, only a small fraction of the oxidized total organics condense onto the particles in polluted environments. Meanwhile, the OH and O3 oxidation mechanism contribute 5.5% and 94.5% to the volume concentration of small particles, indicating the particle growth is more controlled by the precursor gases and their oxidation by O3. [ABSTRACT FROM AUTHOR]

Novel and robust method for determination of uranium isotopes in various environmental materials is presented. The method is based on total decomposition of the solid materials by the use of closed vessels microwave acid digestion systems and pre concentration of uranium from the liquid samples. The separation of uranium from interfering radionuclides and stable matrix elements is attained by liquid-liquid extraction with triisooctylamine/xylene in sulfuric and consecutively in hydrochloric acid media. Purified uranium is electrodeposited on a stainless steel disks and then measured by alpha spectrometry. The critical steps in the method were examined. The analytical method has been successfully applied to the determination of uranium isotopes in mineral and tap waters, as well as in soils from Northwestern Bulgaria. The analytical quality was checked by analyzing reference materials with different matrices. [ABSTRACT FROM AUTHOR]

A series of major eruptions of the Eyjafjallajökull volcano in Iceland started on 14 April 2010 and continued until the end of May 2010. The volcanic emissions moved over nearly the whole of Europe and were observed first on 16 April 2010 in Southern Germany with different remote sensing systems from the ground and space. Enhanced PM10 and SO2 concentrations were detected on 17 April at mountain stations (Zugspitze/Schneefernerhaus and Schauinsland) as well as in Innsbruck by in situ measurement devices. On 19 April intensive vertical mixing and advection along with clear-sky conditions facilitated the entrainment of volcanic material down to the ground. The subsequent formation of a stably stratified lower atmosphere with limited mixing near the ground during the evening of 19 April led to an additional enhancement of near-surface particle concentrations. Consequently, on 19 April and 20 April exceedances of the daily threshold value for particulate matter (PM10) were reported at nearly all monitoring stations of the North Alpine foothills as well as at mountain and valley stations in the northern Alps. The chemical analyses of ambient PM 10 at monitoring stations of the North Alpine foothills yielded elevated Titanium concentrations on 19/20 April which prove the presence of volcanic plume material. Following this result the PM 10 threshold exceedances are also associated with the volcanic plume. The entrainment of the volcanic plume material mainly affected the concentrations of coarse particles (>1 µm) -- interpreted as volcanic ash -- and ultrafine particles (<100 nm), while the concentrations of accumulation mode aerosol (0.1-1 µm) were not changed significantly. With regard to the occurrence of ultrafine particles, it is concluded that their formation was triggered by high sulphuric acid concentrations which are necessarily generated by the photochemical processes in a plume rich in sulphur dioxide under high solar irradiance. It became evident that during the course of several days, the Eyjafjallajökull volcanic emissions influenced the near-surface atmosphere and thus the ambient air quality. Although the volcanic plume contributed to the overall exposure of the population of the northern Alpine region on two days, only minor effects on the exacerbation of respiratory and cardiovascular symptoms can be expected. [ABSTRACT FROM AUTHOR]

The ability of coated mineral dust particles to act as ice nuclei (IN) was investigated at LACIS (Leipzig Aerosol Cloud Interaction Simulator) during the FROST1- and FROST2-campaigns (Freezing of dust). Sulphuric acid was condensed on the particles which afterwards were optionally humidified, treated with ammonia vapour and/or heat. By means of aerosol mass spectrometry we found evidence that processing of mineral dust particles with sulphuric acid leads to surface modifications of the particles. These surface modifications are most likely responsible for the observed reduction of the IN activation of the particles. The observed particle mass spectra suggest that different treatments lead to different chemical reactions on the particle surface. Possible chemical reaction pathways and products are suggested and the implications on the IN efficiency of the treated dust particles are discussed. [ABSTRACT FROM AUTHOR]

As part of the 2008 Campaign of Air Quality Research in Beijing and Surrounding Regions (CAREBeijing 2008), measurements of gaseous sulfuric acid (H2SO4) have been conducted at an urban site in Beijing, China from 7 July to 25 September 2008 using atmospheric pressure ion drift -- chemical ionization mass spectrometry (AP-IDCIMS). This represents the first gaseous H2SO4 measurements in China. Diurnal profile of sulfuric acid is strongly dependent on the actinic flux, reaching a daily maximum around noontime and with an hourly average concentration of 5x106 molecules cm-3. Simulation of sulfuric acid on the basis of the measured sulfur dioxide concentration, photolysis rates of ozone and nitrogen dioxide, and aerosol surface areas captures the trend of the measured H2SO4 diurnal variation within the uncertainties, indicating that photochemical production and condensation onto preexisting particle surface dominate the observed diurnal H2SO4 profile. The frequency of the peak H2SO4 concentration exceeding 5x106 molecules cm-3 increases by 16% during the period of the summer Olympic Games (8-24 August 2008), because of the implementation of air quality control regulations. Using a multivariate statistical method, the critical nucleus during nucleation events is inferred, containing two H2SO4 molecules (R²=0.85). The calculated condensation rate of H2SO4 can only account for 10-25 % of PM1 sulfate formation, indicating that either much stronger sulfate production exists at the SO2 source region or other sulfate production mechanisms are responsible for the sulfate production. [ABSTRACT FROM AUTHOR]

The granulation of composite mixtures with potential use in agriculture as soil-conditioners gives good possibility for their mechanical distribution in the soil through different fertilizer-spreader machines. The granulated products ensure slower speed of the nutrients extraction in the soil solution and in the same time long-term presence in the soils and better utilization by the plants. This work presents the results from investigations on the granulation of composite mixtures for production of soil-conditioners. All used mixtures are based on ashes from burning wooden wastes and green lye -- wastes from pulp production. For some mixtures sulphuric acid was also used in order to compensate of alkaline reactions of other components and to obtain better properties of the soil-conditioner. The granulation process was realized by the method of press granulation, and the obtained granules were tested with a hydraulic press to determine the compressive strength of the products. The obtained values were compared with similar products. The moisture content of the granulated soil-conditioners were determined and compared also with similar type soil-conditioners. [ABSTRACT FROM AUTHOR]

The effectiveness of persulfate oxidation for the destruction of tetrachlorobiphenyl a representative polychlorobiphenyl (PCB), in spiked subsurface soils was evaluated in this study. Kaolin and glacial till soils were selected as representative low permeability soils; both soils were spiked with 50 mg PCB per dry kilogram of soil. Activation of persulfate oxidation was necessary to achieve effective destruction of PCBs in soils. As persulfate oxidation activators, temperature and high pH were used in order to maximize PCB destruction. In addition, the effect of oxidant dose and reaction time was investigated. The optimal dose for persulfate was found to be 30% for maximum oxidation. The persulfate activation with temperature of 45°C was superior to persulfate activation with high pH (pH 12), where higher PCB destructions were observed for kaolin and glacial till soils. PCB destruction increased with reaction time, where maximum degradation was achieved after 7 days. The highest PCB destruction was achieved with temperature activation at 45°C using a dosage of 30% persulfate at pH 12 for kaolin and glacial till soils after 7 days. [ABSTRACT FROM AUTHOR]

In order to model accurately the size and number of atmospheric particles, it is necessary to predict aerosol nucleation rates. However, the explicit prediction of the sulfuric acid vapor concentration may become computationally intensive when nucleation and condensation are simultaneously occurring. In this article, we develop and test a computationally efficient solution to the problem of solving for the sulfuric acid vapor concentration. Rather than explicitly solving the differential equation for the temporal profile of sulfuric acid vapor, we assume that the sulfuric acid vapor is at the concentration in steady state with its source (oxidation of SO2) and sinks (condensation and nucleation); this is known as the Pseudo-Steady-State Approximation (PSSA). Two versions of a box model with online size-resolved aerosol microphysics were developed to test the PSSA; (1) a “benchmark model” that solves explicitly for the sulfuric acid vapor concentration, and (2) a “PSSA model” that uses the PSSA. A wide array of atmospheric conditions was used to compare the benchmark and PSSA models. The mean difference in the total number of particles in the two models with diameters larger than 10 nm was only 1.8% and 1.1% in lower troposphere simulations after 2 and 6 hours, and 3.8% and 2.3% in the upper troposphere simulations after 2 and 6 h. The PSSA model was faster in 97% of the tests, more than ten times faster in 91% of the points, and more than 100 times faster in 69% of the tests. [ABSTRACT FROM AUTHOR]

This article discusses the use of solvents to remove coal ash and generate a clean form of coal. The presence of nanoscale titanium compounds, including titanium dioxide, in this clean coal is noted as a concern because of its negative environmental impact. The Argonne premium coal samples (APCS) Illinois No. 6 (IL) bituminous coal and wyodak-anderson (WY) subbituminous coal are used in this research. The effects of acetic and sulphuric acids as solvents for coal are discussed. The different qualities of titanium compounds in different types of coal are described. The levels of titanium speciation found in these coals is discussed.

A simple, rapid, and economical spectrophotometric method is developed for the determination of sulfur dioxide in sugar and air samples. The developed method is based on a red-brown peroxovanadate complex (λmax = 470 nm) produced in 2 M sulfuric acid when ammonium metavanadate is treated with hydrogen peroxide. Under fixed concentrations of hydrogen peroxide and ammonium metavanadate, when sodium metabisulfite (Na2S2O5 = 2SO2) is added, it preferentially reacts with hydrogen peroxide producing sulfuric acid, and the unreacted hydrogen peroxide then reacts with ammonium metavanadate; therefore, the concentration of sulfur dioxide is directly proportional to a decrease in the concentration of the peroxovanadate complex. The stoichiometric ratio between hydrogen peroxide and ammonium metavanadate as well as the stability constant of the complex are determined by the modified Job’s method and the respective values are found to be 1: 1 and 2.5 × 104 mol−1 L, respectively. The system obeys Lambert-Beer’s law in the concentration range 3.57–64.26 ppm of sulfur dioxide. The molar absorptivity, correlation coefficient, and Sandell’s sensitivity values are found to be 0.649 × 103 L mol−1 cm−1, 0.9908, and 0.1972 μg cm−2, respectively. The method is applied to the determination of sulfur dioxide present in commercial sugars and air samples. The results obtained are reproducible with a standard deviation of 0.02–0.05. For method validation, sulfur dioxide is also determined separately following the AOAC method for an air sample and the ICUMSA method for commercial sugars. The results obtained by the developed and official methods are in good agreement. [ABSTRACT FROM AUTHOR]

In our aim to decrease the consumption of materials and energy and promote the use of renewable resources, such as biofuels, rises the need to measure materials and energy fluxes. This paper suggests the use of Exergy Flow Analysis (ExFA) as an environmental assessment tool to account wastes and emissions, determine the exergetic efficiency, compare substitutes and other types of energy sources: all useful in defining environmental and economical policies for resource use. In order to illustrate how ExFA is used, it is applied to the process of biodiesel production. The results show that the production process has a low exergy loss (492MJ). The exergy loss is reduced by using potassium hydroxide and sulphuric acid as process catalysts and it can be further minimised by improving the quality of the used cooking oil. [Copyright &y& Elsevier]

The article presents a study on the impact of sedimentary phosphorus (P) on the availability of lead (Pb) in mytilus edulis. The study had investigated sediments containing P in Belledune Harbor and the sulfuric acids, which were caused during the purification of Pb, that lead to metal pollution. The study indicates the inverse proportionality relationship of Pb levels with P levels.

Wind-blown rain, rain splash, and films of free moisture play important roles in the epidemiology of many plant diseases. The effects of simulated rain acidified with sulfuric acid were studied on several host-parasite systems. Plants were exposed in greenhouse or field to simulated rain of pH 3.2 ± 0.1 or pH 6.0 ± 0.2. Simulated 'rain' of pH 3.2 resulted in: (1) an 86% inhibition in telia production of Cronartium fusiforme on Quercus phellos; (2) a 66% inhibition of reproduction of Meloidogyne hapla on field-grown Phaseolus vulgaris; (3) a 10% decrease in the severity of Uromyces phaseoli on field-grown Phaseolus vulgaris; and (4) an inhibition of Rhizobium nodulation of Phaseolus vulgaris and Glycine max by an average of 73%. Effects on halo blight of kidney bean (caused by Pseudomonas phaseolicola) depended upon the segment of the disease cycle in which the 'rain' occurred: (a) simulated rain of pH 3.2 applied to plants before inoculation stimulated disease development; (b) suspension of inoculum in 'rain' of pH 3.2 decreased inoculum potential; and (c) 'rain' of pH 3.2 applied to plants after infection inhibited disease development. Scanning electron microscopy of epicuticular waxes on leaves of Quercus phellos and Phaseolus vulgaris showed marked erosion of those surfaces by 'rain' of pH 3.2, indicating possible influences on the structure and function of plant cuticles. These results suggest that the acidity of rain is a new parameter of environmental concern, and underline the need for study of the consequences of prolonged exposure of both agronomic and natural ecosystems to this stress factor. [ABSTRACT FROM AUTHOR]

The article describes the case of a 53-year-old male patient with a history of cutaneous lesions on the limbs which was diagnosed as leukocytoclastic vasculitis associated with sulfuric acid inhalation. The diagnosis was confirmed after the patient was subjected to anamnesis, skin biopsy and laboratory studies. A discussion on the physiological impact of sulfuric acid is presented.