Ratio Of SO2 Research Articles

Source and formation of secondary particulate matter in PM2.5 in Asian continental outflow

Fifty‐five 48‐h PM2.5 samples were collected from March 2003 to January 2004 at Changdao, a resort island in Bohai Sea/Yellow Sea in Northern China. Sulfate, nitrate and ammonium accounted for 54 ± 9% of the PM2.5 mass concentration (annual average 47 μg m−3) while organic matter and K+ contributed to 27 ± 7% and 7 ± 7% of the total mass, respectively. The ratios of SO42− to NO3− mass concentrations could be divided into two regimes and demarcated at nitrate concentration of 5 μg m−3. In the low NO3− regime, NO3−, SO42− and EC were well correlated to K+, and the estimated contributions of NO3−, SO42− and EC from biomass burning were 50 ± 27%, 38 ± 24% and 47 ± 27%, respectively. These correlations substantially decreased in the high NO3− regime reflecting fossil fuel combustion and formation of ammonium nitrate and the estimated contributions of NO3−, SO42− and EC from biomass burning were 16 ± 12%, 28 ± 18% and 27 ± 16%, respectively. In most samples, the equivalent ratios of total anion to total cation concentrations were greater than unity, suggesting that the aerosols were acidic. When [H+] > 0, a moderately good linear correlation of the estimated aerosol acidity [H+] with the water‐soluble organic carbon (WSOC) was observed with R2 = 0.70 and an increase of [H+] by 100 neq m−3 would increase 1.2 μg m−3 WSOC in PM2.5. When [H+] > 0, an increase of [H+] by 100 neq m−3 would increase 1.4 μg m−3 of secondary organic carbon (SOC) in PM2.5. Moreover, the correlation analysis result suggested that 60% of the estimated SOC (on average) in PM2.5 were water‐soluble.

Halogens and trace metal emissions from the ongoing 2008 summit eruption of Kīlauea volcano, Hawai`i

Volcanic plume samples taken in 2008 and 2009 from the Halema`uma`u eruption at Kīlauea provide new insights into Kīlauea’s degassing behaviour. The Cl, F and S gas systematics are consistent with syn-eruptive East Rift Zone measurements suggesting that the new Halema`uma`u activity is fed by a convecting magma reservoir shallower than the main summit storage area. Comparison with degassing models suggests that plume halogen and S composition is controlled by very shallow (<3m depth) decompression degassing and progressive loss of volatiles at the surface. Compared to most other global volcanoes, Kīlauea’s gases are depleted in Cl with respect to S. Similarly, our Br/S and I/S ratio measurements in Halema`uma`u’s plume are lower than those measured at arc volcanoes, consistent with contributions from the subducting slab accounting for a significant proportion of the heavier halogens in arc emissions. Analyses of Hg in Halema`uma`u’s plume were inconclusive but suggest a flux of at least 0.6kgday−1 from this new vent, predominantly (>77%) as gaseous elemental mercury at the point of emission. Sulphate is an important aerosol component (modal particle diameter ∼0.44μm). Aerosol halide ion concentrations are low compared to other systems, consistent with the lower proportion of gaseous hydrogen halides. Plume concentrations of many metallic elements (Rb, Cs, Be, B, Cr, Ni, Cu, Mo, Cd, W, Re, Ge, As, In, Sn, Sb, Te, Tl, Pb, Mg, Sr, Sc, Ti, V, Mn, Fe, Co, Y, Zr, Hf, Ta, Al, P, Ga, Th, U, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Tm) are elevated above background air. There is considerable variability in metal to SO2 ratios but our ratios (generally at the lower end of the range previously measured at Kīlauea) support assertions that Kīlauea’s emissions are metal-poor compared to other volcanic settings. Our aerosol Re and Cd measurements are complementary to degassing trends observed in Hawaiian rock suites although measured aerosol metal/S ratios are about an order of magnitude lower than those calculated from degassing trends determined from glass chemistry. Plume enrichment factors with respect to Hawaiian lavas are in broad agreement with those from previous studies allowing similar element classification schemes to be followed (i.e., lithophile elements having lower volatility and chalcophile elements having higher volatility). The proportion of metal associated with the largest particle size mode collected (>2.5μm) and that bound to silicate is significantly higher for lithophiles than chalcophiles. Many metals show higher solubility in pH 7 buffer solution than deionised water suggesting that acidity is not the sole driver in terms of solubility. Nonetheless, many metals are largely water soluble when compared with the other sequential leachates suggesting that they are delivered to the environment in a bioavailable form. Preliminary analyses of environmental samples show that concentrations of metals are elevated in rainwater affected by the volcanic plume and even more so in fog. However, metal levels in grass samples showed no clear enrichment downwind of the active vents.

Infrared satellite observations of hydrogen sulfide in the volcanic plume of the August 2008 Kasatochi eruption

[1] Hydrogen sulphide (H2S) is one of the main trace gases released from volcanoes with yearly global emissions estimated between 1 and 37 Tg. With sulfur dioxide (SO2, 15–21 Tg/year), it dominates the volcanic sulfur budget, and the emission ratio H2S:SO2 is an important geochemical probe for studying source conditions, sulfur chemistry and magma-water interactions. Contrary to SO2, measurements of H2S are sparse and difficult. Here we report the first measurements of a large H2S plume from space. Observations were made with the infrared sounder IASI of the volcanic plume released after the 7–8 August 2008 eruption of Kasatochi volcano. The eruption was characterized by 5 consecutive explosive events. The first events were phreatomagmatic producing a plume rich in water vapor and poor in ash and SO2. We show that the observed H2S plume, calculated at 29 ± 10 kT with integrated columns exceeding 140 ± 25 Dobson Units (DU), is likely associated with these first explosions. H2S:SO2 ratios with maximum values of 12 ± 2 are found, representative of redox conditions in the hydrothermal envelop. With a detection threshold of 25 DU, future space observations of H2S plumes are certain. These will be important for improving the atmospheric sulfur budget and characterizing the H2S:SO2 fingerprint of different eruptions.

Study of Soil Chemical Characteristic by Remote Sensing and GIS Techniques

This research represents part of the current attempts to employ remote sensing data in the scopes of the civil engineering and the geotechnical engineering applications. There is great need to know the kinds of soil and their geotechnical properties, to create recent maps which have the capability and high flexibility to deal with them in digitizing way. Therefore GIS techniques are employed in the soil of area of study . By using ArcView software, a geographical database and information about soil chemical properties analysis have been registered and constructed digitally to represent the geotechnical soil characteristics maps . The work includes the digital image processing ( digital classification techniques) by using ERDAS, ver.,8.4 package, and classify the soil of study area by using the supervise and unsupervised techniques . The geotechnical maps by using GIS techniques depend on remote sensing data are the better to represent the ground truth regarding the characteristics of soil , in comparison with the traditional method, because they are easy way to produce, use, store and update, in addition they save in efforts, time and cost . The results of this study have shown that the soil of study area is gypsum where it ratio exceeded the allowable ratio ( 10.75 % ) for all samples . In addition the total Soluble Salts ratio and SO4 ratio high compared to allowable ratio (10 % , 5 %) respectively .

SO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; and BrO observation in the plume of the Eyjafjallajökull volcano 2010: CARIBIC and GOME-2 retrievals

Abstract. The ash cloud of the Eyjafjallajökull (also referred to as: Eyjafjalla (e.g. Schumann et al., 2011), Eyjafjöll or Eyjafjoll (e.g. Ansmann et al., 2010)) volcano on Iceland caused closure of large parts of European airspace in April and May 2010. For the validation and improvement of the European volcanic ash forecast models several research flights were performed. Also the CARIBIC (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container) flying laboratory, which routinely measures at cruise altitude (≈11 km) performed three dedicated measurements flights through sections of the ash plume. Although the focus of these flights was on the detection and quantification of the volcanic ash, we report here on sulphur dioxide (SO2) and bromine monoxide (BrO) measurements with the CARIBIC DOAS (Differential Optical Absorption Spectroscopy) instrument during the second of these special flights on 16 May 2010. As the BrO and the SO2 observations coincide, we assume the BrO to have been formed inside the volcanic plume. Average SO2 and BrO mixing ratios of ≈40 ppb and ≈5 ppt respectively are retrieved inside the plume. The BrO to SO2 ratio retrieved from the CARIBIC observation is ≈1.3×10−4. Both SO2 and BrO observations agree well with simultaneous satellite (GOME-2) observations. SO2 column densities retrieved from satellite observations are often used as an indicator for volcanic ash. As the CARIBIC O4 column densities changed rapidly during the plume observation, we conclude that the aerosol and the SO2 plume are collocated. For SO2 some additional information on the local distribution can be derived from a comparison of forward and back scan GOME-2 data. More details on the local plume size and position are retrieved by combining CARIBIC and GOME-2 data.

Californian forest fire plumes over Southwestern British Columbia: lidar, sunphotometry, and mountaintop chemistry observations

Abstract. Forest fires in Northern California and Oregon were responsible for two significant regional scale aerosol transport events observed in southern British Columbia during summer 2008. A combination of ground based (CORALNet) and satellite (CALIPSO) lidar, sunphotometry and high altitude chemistry observations permitted unprecedented characterization of forest fire plume height and mixing as well as description of optical properties and physicochemistry of the aerosol. In southwestern BC, lidar observations show the smoke to be mixed through a layer extending to 5–6 km a.g.l. where the aerosol was confined by an elevated inversion in both cases. Depolarization ratios for a trans-Pacific dust event (providing a basis for comparison) and the two smoke events were consistent with observations of dust and smoke events elsewhere and permit discrimination of aerosol events in the region. Based on sunphotometry, the Aerosol Optical Thicknesses (AOT) reached maxima of ~0.7 and ~0.4 for the two events respectively. Dubovik-retrieval values of reff, f during both the June/July and August events varied between about 0.13 and 0.15 μm and confirm the dominance of accumulation mode size particles in the forest fire plumes. Both Whistler Peak and Mount Bachelor Observatory data show that smoke events are accompanied by elevated CO and O3 concentrations as well as elevated K+/SO4 ratios. In addition to documenting the meteorology and physic-chemical characteristics of two regional scale biomass burning plumes, this study demonstrates the positive analytical synergies arising from the suite of measurements now in place in the Pacific Northwest, and complemented by satellite borne instruments.

A top‐down analysis of emissions from selected Texas power plants during TexAQS 2000 and 2006

Airborne measurements were taken downwind of eleven Texas power generation facilities in 2000 and 2006 as part of the two Texas Air Quality Study (TexAQS) campaigns. From these measurements, we determine emission ratios of NOx (= NO + NO2), SO2, and CO to coemitted CO2 for each facility. These measurements provide an independent external assessment of reported emission ratios from continuous emission monitoring systems (CEMS). During the TexAQS study years, we find the SO2/CO2 and NOx/CO2 emission ratios derived from measurements aboard the aircraft agree quantitatively with inventory values from CEMS, with standard deviations of less than ±14%. We document significant decreases in atmospheric mixing ratios of NOx as a result of emission reductions due to controls implemented at the W. A. Parish plant after TexAQS 2000. For several of the facilities, CO emissions appear relatively constant in time. Derived CO/CO2 emission ratios agree substantially better with Texas Commission on Environmental Quality inventories in 2006 than in 2000, which we attribute to better inventory data from three facilities that installed CO CEMS between the two study years and not because of any significant change in CO emissions. Other plants appear to have varying CO emissions over time, complicating comparison to annual inventory values. Finally, we use two independent NO2 measurements, along with measurements of O3, NO3, and N2O5, to quantify the fraction of NOx directly emitted as NO2 from the Oklaunion Power Plant, providing the first quantitative estimate of NO2 emissions from a power generation facility using ambient data.

Aged particles derived from emissions of coal-fired power plants: The TERESA field results

The Toxicological Evaluation of Realistic Emissions Source Aerosols (TERESA) study was carried out at three US coal-fired power plants to investigate the potential toxicological effects of primary and photochemically aged (secondary) particles using in situ stack emissions. The exposure system designed successfully simulated chemical reactions that power plant emissions undergo in a plume during transport from the stack to receptor areas (e.g., urban areas). Test atmospheres developed for toxicological experiments included scenarios to simulate a sequence of atmospheric reactions that can occur in a plume: (1) primary emissions only; (2) H2SO4 aerosol from oxidation of SO2; (3) H2SO4 aerosol neutralized by gas-phase NH3; (4) neutralized H2SO4 with secondary organic aerosol (SOA) formed by the reaction of α-pinene with O3; and (5) three control scenarios excluding primary particles. The aged particle mass concentrations varied significantly from 43.8 to 257.1 µg/m3 with respect to scenario and power plant. The highest was found when oxidized aerosols were neutralized by gas-phase NH3 with added SOA. The mass concentration depended primarily on the ratio of SO2 to NOx (particularly NO) emissions, which was determined mainly by coal composition and emissions controls. Particulate sulfate (H2SO4 + neutralized sulfate) and organic carbon (OC) were major components of the aged particles with added SOA, whereas trace elements were present at very low concentrations. Physical and chemical properties of aged particles appear to be influenced by coal type, emissions controls and the particular atmospheric scenarios employed.

Salinity and specific ion effects on onion establishment in relation to disposal of desalting concentrates

Concentrate from nanofiltration (NF) is usually enriched with divalent ions, and low in proportions of monovalent ions. Therefore, its disposal to irrigation water may not be deleterious, especially for growing crops susceptible to specific effects of Na and/or Cl. This possibility was examined in a greenhouse by observing effects of four levels of salinity and ion composition of irrigation solutions on seedling emergence and growth of onions (sensitive to Cl ions) in loamy sand and silt loam. Seedling emergence from surface-irrigated loamy sand was excellent, regardless of the saline solutions used. In subirrigated silt loam, however, seedling emergence was reduced by increasing initial soil salinity and salinity of irrigation solutions, but not by the ion composition. Seedling growth was reduced by increasing Cl to SO4 ratio only when the Cl concentration of irrigation solutions exceeded a concentration between 10 and 20 me L-1. The Cl effect seems to appear after seedling growth is first reduced by sal...

Properties of Ionic Liquids Absorbing SO2 and the Mechanism of the Absorption

Room-temperature ionic liquids (ILs) have been demonstrated to absorb SO(2) efficiently. However, after absorbing a large amount of SO(2), the viscosity, the conductivity, and the density of the ILs have not been studied systematically, and the mechanism of the interaction between SO(2) and ILs is still being disputed. In this work, two kinds of ILs (task-specific ILs and normal ILs) have been studied to absorb pure SO(2) at atmospheric pressure. It is found that the viscosity, the conductivity, and the density show different behaviors between task-specific ILs and normal ILs. For the task-specific ILs to absorb SO(2), before a 0.5 mol ratio of SO(2) to IL, the viscosity and density increase, and the conductivity decreases with an increase of the mole ratio of SO(2) to IL. After that, the conductivity and density increase, and the viscosity decreases with further increasing the mole ratio of SO(2) to IL. However, for the normal ILs, the conductivity and density increase and the viscosity decreases with an increase of the mole ratio of SO(2) to IL. A new mechanism of ILs absorbing SO(2) has been proposed. Task-specific ILs can chemically absorb SO(2) when the mole ratio of SO(2) to IL is not more than 0.5, and they can physically absorb SO(2) when the mole ratio is more than 0.5. The normal ILs can only physically absorb SO(2).

Fate of SO2 in the ancient Martian atmosphere: Implications for transient greenhouse warming

There is increasing evidence that sulfur played an important role on early Mars. Sulfur is distributed ubiquitously on the Martian surface, and sulfur in Martian meteorites carries the signature of atmospheric interactions. Recent work suggests that the radiative properties of sulfur volatiles that were degassed into the Martian atmosphere may have caused a greenhouse effect early in the planet's history. It remains unclear, however, over what timescales warming from sulfur volatiles would have persisted, and consequently how significant this warming may have been. While most photochemistry research to date has concentrated on current Martian conditions, the ancient Martian atmosphere was thicker, warmer, and more reducing than the current regime. Here we investigate sulfur photochemistry in a 500 mb ancient Martian atmosphere. After adapting a model used to study sulfur photochemistry on Earth during the Archean, we find a short lifetime for SO2 in the current Martian atmosphere, similar to results of other photochemical studies. However, our simulations suggest that moderate mixing ratios of SO2 (10−8 ≤ f(SO2) ≤ 10−6) could have persisted in the ancient Martian atmosphere for hundreds of years, generating short but potent warming events following episodes of volcanic activity.

Biodiesel from Waste Cooking Oil via Heterogeneous Superacid Catalyst SO42−/ZrO2

The solid superacid catalyst SO42−/ZrO2 was prepared by impregnation and characterized by infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction. Their performances were evaluated by the transesterification reaction of waste cooking oil (WCO) with methanol. The influence of the load ratio of SO42−/ZrO2, molar ratio of methanol/waste cooking oil, catalyst amount, reaction temperature, and reaction time on biodiesel yield was investigated. Under a condition of methanol/WCO molar ratio of 9:1, a catalyst amount of 3 wt %, reaction time of 4 h, and reaction temperature of 120 °C, 93.6% of biodiesel yield was obtained.

The potential importance of frost flowers, recycling on snow, and open leads for ozone depletion events

Abstract. We present model studies with the one-dimensional model MISTRA to investigate the potential role of frost flowers, recycling on snow, and open leads in the depletion of tropospheric ozone in the Arctic spring. In our model, we assumed frost flower aerosols to be the major source of bromine. We show that a major ozone depletion event can be satisfactorily reproduced only if the recycling on snow of deposited bromine into gas phase bromine is assumed. In the model, this cycling is more efficient than the bromine explosion process and maintains sufficiently high levels of bromine to deplete ozone down to few nmol mol−1 within four days. We assessed the influence of different surface combinations (open lead/frost flowers) on the chemistry in the model. Results showed noticeable modifications affecting the composition of aerosols and the deposition velocities. A model run with a series of coupled frost flower fields and open leads, separated by large areas of snow, showed results comparable with field observations. In addition, we studied the effects of modified temperature of either the frost flower field or the ambient airmass. A warmer frost flower field increases the relative humidity and the aerosol deposition rate. The deposition/re-emission process gains in importance, inducing more reactive bromine in the gas phase, and a stronger ozone depletion. A decrease of 1K in airmass temperature shows in our model that the aerosol uptake capacities of all gas phase species substantially increases, leading to enhanced uptake of acids from the gas phase. Consequently, the so-called bromine explosion accelerated and O3 mixing ratios decreased. In our model representation, variations in wind speed affected the aerosol source function and influenced the amount of bromine in the atmosphere and thus the ozone depletion strength. Recent studies have suggested the important role of the precipitation of calcium carbonate (CaCO3) out of the brine layer for the possible acidification of the liquid phase by acid uptake. Our investigation showed that this precipitation is a crucial process for the timing of the bromine explosion in aerosols. Nevertheless, model runs with either 50% precipitation or complete precipitation displayed a relatively weak difference in ozone mixing ratios after four simulated days. By considering conditions typical for "Arctic Haze" pollution events at the start of the run we obtained a low pH in frost flower aerosols due to a greater mixing ratio of SO2, and a strong recycling efficiency via large aerosol number concentration. The aerosol acidification during a haze event most likely intensifies the ozone depletion strength and occurrence. The comparison between our modeled deposition on snow and sampled snow at Barrow (Alaska) shows that approximately 75% of deposited bromine may be re-emitted into the gas phase as Br2/BrCl. Among several non-halogen fluxes from the snow, model simulations showed that only HONO affects the chemistry. Finally, we investigated the release of Br2 potentially produced by heterogeneous reactions directly on frost flowers. In this case, we obtained unrealistic results of aerosol compositions and deposition rates on snow compared to observations in the Arctic.

First observations of SO2 above Venus' clouds by means of Solar Occultation in the Infrared

Solar Occultation in the Infrared (SOIR) is a part of the Spectroscopy for Investigation of Characteristics of the Atmosphere of Venus (SPICAV)/SOIR occultation experiment on board Venus Express dedicated to the study of gaseous and aerosol vertical structure of Venus' mesosphere. SOIR is an echelle spectrometer with acoustooptic selection of diffraction orders operating in the wavelengths range of 2.2–4.3 μm at high spectral resolution (λ/Δλ ∼ 20,000). Detection of minor constituents such as CO, H2O, HDO, HCl, HF, and SO2, at altitudes between 65 and 130 km has been demonstrated. We report results from a series of six occultations with observations of the 4‐μm SO2 band at latitudes 69°–88°N and 23°–30°N. It is the first time when the vertical distribution of SO2 is retrieved above the clouds with the help of solar occultation direct method. The sulfur dioxide transmission spectrum is measured on a background of strong CO2 absorption. Each retrieved vertical profile of SO2 is characterized by few points; the mixing ratio of SO2 being ∼0.1 ppm with scale height 1 ± 0.4 km for polar measurements (evening observations) and ∼1 ppm with scale height 3 ± 1 km at low latitudes (morning observations) at the altitude of about 70 km. Upper limits of &lt;∼0.05 ppm are established around 75 km.

First Essays for Cadmium Wastewater Elimination by Sulphate-Reducing Bacteria

Sulphate-reducing bacteria (SRB) are anaerobic bacteria that couple the oxidation of simple organic compounds to the reduction of sulphate to sulphide. SRB have become important components of bioremediation systems. In this work, a natural SRB sludge was collected in the coastal mud flat of Colindres (Cantabria, Spain) and the removal of soluble cadmium as cadmium sulphide from a synthetic feeding was studied. Discontinuous experiments were performed at room temperature, using four 600 ml reactors. In stage 1, a 250 mL biomass solution (18.16 g/L of volatile matter) was introduced in each reactor and was fed with a solution of cadmium sulphate, sodium sulphate and sucrose as carbon and energy source. The Chemical Oxygen Demand (COD) to SO4-2 ratio (this SO4-2 coming from Na2SO4) was 10 in all the stages of the four reactors, and the different cadmium content tested in each reactor varied from 4 to 12 mg/L. Stages 2, 3, 4 and 5 were performed with the same biomass but with higher initial cadmium amount, from 16 to 300 mg/L, in order to determine the amount of metal causing inhibition of the bacterial activity. Soluble cadmium was analyzed by Atomic Absorption Spectrometry. Additionally in stage 4, the evolution of pH and COD was studied. Results indicated that inhibition of biomass was not found up to a Cd concentration of 300 mg/L. Continuous experiments were performed in an UASB reactor of 1 litter of useful capacity, being the hydraulic residence time 0.833 days and 720 mg of COD/day the organic matter in the influent. After a period of acclimation, biomass was fed with increasing amounts of soluble Cadmium and the specific rate of cadmium elimination was determined.

Aerosol and fresh snow chemistry in the East Rongbuk Glacier on the northern slope of Mt. Qomolangma (Everest)

An intensive and simultaneous sampling for aerosol and fresh snow was conducted at Repula Col of the East Rongbuk Glacier near Mt. Qomolangma during the late Indian summer monsoon season in 2003. Aerosol and snow chemistry (including the species of Na+, K+, Mg2+, Ca2+, Cl−, SO42−, and NO3−) is analyzed and discussed. Anions account for a majority of the air quality, and SO42− is the most loaded species. Local emission by land weathering does not contribute significantly to the loading of Mg2+ and Ca2+, and their high concentration is related to their continental desert sources. The meridional dynamic force of Indian monsoon is efficient to the loading of Na+, and Na+/Ca2+ could be used to distinguish air masses of maritime or continental which dominate the air quality. The signal of crustal SO42− from Central/West Asia or farther Africa is weak, and mixed sources (anthropogenic and crustal) of SO42− dominate its loading in aerosol samples. Air–snow scavenging ratios of these species are calculated and compared with the other results in some previous studies. The scavenging ratio of SO42− as the most heavily loaded species is around 200, which is comparable with that in Greenland.

Removal of sulfur dioxide and formation of sulfate aerosol in Tokyo

Ground‐based in situ measurements of sulfur dioxide (SO2) and submicron sulfate aerosol (SO42−) together with carbon monoxide (CO) were conducted at an urban site in Tokyo, Japan from spring 2003 to winter 2004. The observed concentrations of SO2 were affected dominantly by anthropogenic emissions (for example, manufacturing industries) in source areas, while small fraction of the data (&lt;30%) was affected by large point sources of SO2 (power plant and volcano). Although emission sources of CO in Tokyo are different from those of SO2, the major emission sources of CO and SO2 are colocated, indicating that CO can be used as a tracer of anthropogenic SO2 emissions in Tokyo. The ratio of SO42− to total sulfur compounds (SOx = SO2 + SO42−) and the remaining fraction of SOx, which is derived as the ratio of the linear regression slope of the SOx‐CO correlation, is used as measures for the formation of SO42− and removal of SOx, respectively. Using these parameters, the average formation efficiency of SO42− (i.e., amount of SO42− produced per SO2 emitted from emission sources) are estimated to be 0.18 and 0.03 in the summer and winter periods, respectively. A simple box model was developed to estimate the lifetime of SOx. The lifetime of SOx for the summer period (26 h) is estimated to be about two times longer than that for the winter period (14 h). The seasonal variations of the remaining fraction of SOx, estimated formation efficiency of SO42−, and lifetime of SOx are likely due to those of the boundary layer height and photochemical activity (i.e., hydroxyl radical). These results provide useful insights into the formation and removal processes of sulfur compounds exported from an urban area.

Anaerobic pond treatment of wastewater containing sulphate

Anaerobic ponds are usually used for treatment of industrial and agricultural wastes which contain high organic matter and sulphate. Competition for substrate between sulphate reducing bacteria and methane producing archaea, and the inhibitory effects of sulphide produced from microbial sulphate reduction reported in the literature varied considerably. In this research, a laboratory scale column-in-series anaerobic pond reactor, consisting of five cylindrical columns of acrylic tubes, was operated to evaluate the effect of COD and sulphate ratio on pond performance treating wastewater containing high organic matter and sulphate from a tapioca starch industry. The result depicted that no adverse effect of COD:SO4 ratios between 5 and 20 on overall COD removal performance of anaerobic pond operated with organic loading rate (OLR) of 150 to 600 g COD/m3d. Sulphate reducing bacteria could out-compete methane producing archaea for the same substrate at COD:SO4 ratio equal to or lower than 5 and OLR greater than 300 g COD/m3d. Sulphide inhibition was not observed on overall performance of pond up to an influent sulphate concentration of 650 mg/L.

Efficient air pollution abatement for regions in China

This paper computes the efficient air pollution abatement ratios of 30 regions in China during the period 1996–2002. Three air emissions (SO2, soot and dust) are considered. Data envelopment analysis (DEA) with a single output (real GDP) and five inputs (labour, real capital stock, SO2, dust and soot emissions) is used to compute the target emissions of each region for each year. The efficient abatement ratios of each region in each year are then obtained by dividing the target emission by the actual emission of an air pollutant. Our major findings are: 1. The eastern area is the most efficient region with respect to SO2, soot and dust emissions in every year during the research period. 2. The eastern, central and western areas have the lowest, medium and highest 1996–2002 average target abatement ratios of SO2 (22.09%, 42.23% and 57.58%), soot (26.19%, 56.34% and 66.37%) and dust (15.20%, 29.09% and 40.59%), respectively. 3. These results are consistent with the Environmental Kuznets Curve (EKC) theory, whereby a more developed area will use environmental goods more efficiently than a less developed area. 4. Compared to dust emission, the average target abatement ratios for SO2 and soot emissions (as direct outcomes of burning coal) are relatively much higher for all three areas.

The effect of various iron hydroxide concentrations on the anaerobic fermentation of sulfate-containing model wastewater

The addition of iron hydroxide and iron-reducing bacteria into a fermenter for anaerobic processing of sulfate-containing sewage was shown to decrease sulfate reduction and sulfide concentration, while increasing the total organic carbon (TOC) and methane production. The effect of iron (III) in sulfate-containing sewage depended on its dose, which can be expressed as molar ratio Fe(III)/SO4(2-). Sulfide concentration increased monotonically, reaching 91 mg/l and 45 mg/l after 15 days of processing at Fe(III)/SO4(2-) ratios of 0.06 and 0.5, respectively. However, soluble sulfide production was not observed at ratios equaling 1 and 2. At ratios of 0.06, 0.5, 1, and 2, the maximum rates of TOC removal were 0.75, 1.15, 1.39, and 1.55 g TOC/g of organic matter (OM) per 1 h. Methane production rates were 0.039, 0.047, 0.064, and 0.069 mg/g OM per 1 h, with the mean relative amounts of methane in the biogas being equal to 25, 41, 55, and 62%, respectively. These data can be applied to the development of new methods of anaerobic purification of sulfate-containing sewage.