Sulfate,chloride and fluoride retention in Andosols exposed to volcanic acid emissions

The continuous emissions of SO(2), HCl and HF by Masaya volcano, Nicaragua, represent a substantial source of atmospheric S-, Cl- and F-containing acid inputs for local ecosystems. We report on the effects of such acid depositions on the sulfate, chloride and fluoride contents in soils (0-40 cm) from two distinct transects located downwind from the volcano. The first transect corresponds to relatively undifferentiated Vitric Andosols, and the second transect to more weathered Eutric Andosols. These soils are exposed to various rates of volcanogenic acid addition, with the Vitric sites being generally more affected. Prolonged acid inputs have led to a general pH decrease and reduced exchangeable base cation concentrations in the Andosols. The concentrations of 0.5 M NH(4)F- and 0.016 M KH(2)PO(4)-extractable sulfate (NH(4)F-S and KH(2)PO(4)-S, respectively) indicate that volcanic S addition has increased the inorganic sulfate content of the Vitric and Eutric soils at all depths. In this process, the rate of sulfate accumulation is also dependent on soil allophane contents. For all soils, NH(4)F extracted systematically more (up to 40 times) sulfate than KH(2)PO(4). This difference suggests sulfate incorporation into an aluminum hydroxy sulfate phase, whose contribution to total inorganic sulfate in the Vitric and Eutric Andosols is estimated from approximately 34 to 95% and approximately 65 to 98%, respectively. The distribution of KH(2)PO(4)-extractable chloride in the Vitric and Eutric Andosols exposed to volcanic Cl inputs reveals that added chloride readily migrates through the soil profiles. In contrast, reaction of fluoride with Al and Fe oxyhydroxides and allophanes is an important sink mechanism in the Masaya Andosols exposed to airborne volcanic F. Fluoride dominates the anion distribution in all soil horizons, although F is the least concentrated element in the volcanic emissions and depositions. The soil anion distribution reflects preferential retention of fluoride over sulfate and chloride, and of sulfate over chloride. The primary acidifying agent of the Andosols subject to the volcanic acid inputs is HCl.     

An assessment of the emissions inventory processing systems EMS-2001 and SMOKE in grid-based air quality models

In the United States, emission processing models such as Emissions Modeling System-2001 (EMS-2001), Emissions Preprocessor System-Version 2.5 (EPS2.5), and the Sparse Matrix Operator Kernel Emissions (SMOKE) model are currently being used to generate gridded, hourly, speciated emission inputs for urban and regional-scale photochemical models from aggregated pollutant inventories. In this study, two models, EMS-2001 and SMOKE, were applied with their default internal data sets to process a common inventory database for a high ozone (O3) episode over the eastern United States using the Carbon Bond IV (CB4) chemical speciation mechanism. A comparison of the emissions processed by these systems shows differences in all three of the major processing steps performed by the two models (i.e., in temporal allocation, spatial allocation, and chemical speciation). Results from a simulation with a photochemical model using these two sets of emissions indicate differences on the order of +/- 20 ppb in the predicted 1-hr daily maximum O3 concentrations. It is therefore critical to develop and implement more common and synchronized temporal, spatial, and speciation cross-reference systems such that the processes within each emissions model converge toward reasonably similar results. This would also help to increase confidence in the validity of photochemical grid model results by reducing one aspect of modeling uncertainty.     

An estimation of the spatial and temporal distribution of biogenic non-methane hydrocarbon emissions in Greece

The present study presents the first detailed inventory for non-methane hydrocarbon emissions from vegetation over Greece. The emission inventory, based on a Geographic Information System (GIS), has a spatial resolution of 5×5 km² and a time resolution of 1 h. For the area under study, the calculated yearly monoterpene emissions are higher than the corresponding isoprene ones. In addition to the methodology presented here, the CORINAIR methodology was also applied for the calculation of emission rates. This resulted in orders of magnitude differences in the calculated emission rates. The CORINAIR methodology is judged to lead to unrealistically high values of biogenic NMHC emission rates. The temperature dependence of the CORINAIR correction factors seems to affect most the emissions, together with grazing land emission factors.     

An application of a puff dispersion model on power plant emissions in Yatagan region, Turkey

The present paper describes the application of the CALMET meteorological model and CALPUFF plume dispersion model to the Yatagan district to study the impact of Yatagan Power Plant emissions on the SO₂ levels on December 2000 in the region. Results indicate that SO₂ concentrations over the city depend strongly on advected emissions from the power plant and on the local variation of the wind field and limited vertical mixing conditions. It is found that South Westerly and light winds and the night time surface inversion layers lead to accumulation of pollutants coming from the power plant over the Yatagan district. The results are compared with the observations obtained from Local Environmental Authorities of Mugla. The simulation results indicate that the maximum ground level concentrations were found northeast from the source, which agrees with the measurements, but differ in terms of magnitudes.     

An analysis of the SO2 concentration levels in Athens,Greece

In this paper, an analysis of the meteorological parameters that affect SO₂ pollution in Athens, a problem of both local and international concern, is presented. The influence of these meteorological parameters on the SO₂ concentrations has been investigated by a statistical analysis of the daily average SO₂ values measured at six locations in the Athens basin for the six years from 1974 to 1979. Wind speed, minimum temperature and amount of rain has been found to control SO₂ concentrations during the cold season while wind speed, wind direction and relative humidity are central in the warm season. Based on this, multiple regression models, both linear and non-linear, for the prediction of the next day's SO₂ concentration have been derived that explain more than 50% of the data variance. Further improvements on the modelling are contingent on the availability of boundary layer structure data and on details of the local wind field. The meteorology of high concentration episodes has also been examined and the synoptic characteristics for the onset and end of such episodes have been identified. Finally, discriminant analysis classification functions, utilizing forecast meteorological variables have been obtained which are capable of predicting accurately the occurrence of high pollution concentrations.     

Factors determining amounts of fluoride in woodlice Oniscus asellus and Porcellio scaber, litter and soil near an aluminium reduction plant

Amounts of fluoride were measured in whole woodlice Oniscus asellus and Porcellio scaber, together with associated soil and litter, from 17 sites near an aluminium reduction plant at Holyhead, Anglesey, in North Wales. There was a strong positive correlation between amounts of fluoride in woodlice, soil and litter in all comparisons (P<0.02). Highest and lowest fluoride concentrations in woodlice differed by a factor of >50. Where both woodlice species occurred together at the more polluted sites, fluoride levels in Oniscus asellus were generally twice as high as those found in Porcellio scaber. At any given site, amounts of environmental fluoride were determined partly by distance and direction from the pot-rooms of the plant (a function of prevailing winds), modified by the presence of trees which acted as collectors for gaseous and particulate fluoride.     

Temporal variation of fluoride concentration in antlers of roe deer (Capreolus capreolus) living in an area exposed to emissions from iron and steel industry, 1948-2000

Temporal changes of environmental fluoride concentration in the industrialized area of Siegen, western Germany were assessed by studying the fluoride content of antlers (n=116) collected between 1948 and 2000 from the resident roe deer (Capreolus capreolus) population. During the analyzed period, major fluoride emission sources in the study area have been iron- and steelworks. Fluoride concentrations in the antlers ranged between 118 and 5428 mg/kg of bone ash. There was an overall increase in antler fluoride content from the late 1940s/early 1950s to the late 1950s/mid-1960s. Thereafter, antler fluoride levels overall steadily declined. For statistical analysis, the data were grouped into five periods (1948–1959, 1960–1969, 1970–1979, 1980–1989, and 1990–2000). Geometric mean fluoride concentrations of the samples ranged from 323 (period 1990–2000) to 2096 mg/kg of bone ash (period 1960–1969). Sample means for the periods 1980–1989 and 1990–2000, respectively, were always significantly lower than those of older samples. The decrease in antler fluoride concentrations during recent decades suggests a drop of ambient fluoride levels, that is hypothetically attributed to a reduction in the number of emission sources in the area and a decline of fluoride discharges from both local and more distant sources due to improved emission control measures. Comparison with antler fluoride data for other roe deer populations from western Germany further suggests that the roe deer from the Siegen area were recently exposed to an only moderate additional fluoride load from industrial sources. Studying antler fluoride concentrations is a convenient and cost-effective method of monitoring temporal changes in ambient fluoride levels.     

The same-day impact of power plant emissions on sulfate levels in the Los Angeles Air Basin

On the basis of emissions inventories, power plants are estimated to contribute about 45% of the SO₂ released annually in the Los Angeles Basin. The day-to-day variability of SO₂ emissions from power plants is comparable to the day-to-day variability of the basin's ambient sulfate concentrations. This paper examines the statistical relationship between the daily SO₂ emissions of Los Angeles power plants and the 24-h average sulfate concentration monitored at West Covina, a ‘receptor’ site characterized by high sulfate levels. Little correlation between emissions and ambient levels is found, even after much of the influence of meteorology has been factored out The lack of correlation is consistent with the hypothesis that sulfate production in the Los Angeles Basin is limited by factors other than sulfur emissions. It is also consistent with the hypothesis that sulfate production is a linear function of sulfur emissions, if only a small fraction of the average sulfate concentration at West Covina is contributed by the same-day emissions of Los Angeles power plants.     

The application of predictive models in the environmental risk assessment of ECONOR

Environmental risk assessment of products requires information on the physico-chemical properties, persistence and ecotoxicity of the product, its constituents and possible metabolic and degradation products. Experimental investigations are usually required to generate this information and consequently risk assessment can be costly and time consuming. One possible approach to minimising the amount of experimental testing is to supplement experimental data with data predicted using models such as quantitative structure-activity relationships (QSARs). Using these models, information can be generated based primarily on the knowledge of the chemical structure of the substance(s) under investigation. In this study predictive models were used to assess the environmental risk of the veterinary medicine, ECONOR which contains the active ingredient valnemulin. Available experimental data on the properties, degradability and ecotoxicity of valnemulin was supplemented with predicted data. Where possible, experimental data was used to validate the predicted approaches and this indicated that the predictions were accurate. Information on usage, properties and degradability was input to fate models to predict environmental concentrations (PECs) of valnemulin in soil, pore water and groundwater. Comparison of PECs with experimental and predicted ecotoxicity data for valnemulin indicated that that even under 'worst case' scenarios the environmental risk posed by valnemulin was low.     

An analysis of extinction coefficients of particles and water moisture in the stack after flue gas desulfurization at a coal-fired power plant

Two important factors that affect in-stack opacity--light extinction by emitted particles and that by water moisture after a flue gas desulfurization (FGD) unit--are investigated. The mass light extinction coefficients for particles and water moisture, k(p) and k(w), respectively, were determined using the Lambert-Beer law of opacity with a nonlinear least-squares regression method. The estimated k(p) and k(w) values vary from 0.199 to 0.316 m2/g and 0.000345 to 0.000426 m2/g, respectively, and the overall mean estimated values are 0.229 and 0.000397 m2/g, respectively. Although k(w) is 3 orders of magnitude smaller than k(p), experimental results show that the effect on light extinction by water moisture was comparable to that by particles because of the existence of a considerable mass of water moisture after a FGD unit. The mass light extinction coefficient was also estimated using Mie theory with measured particle size distributions and a complex refractive index of 1.5-ni for fly ash particles. The k(p) obtained using Mie theory ranges from 0.282 to 0.286 m2/g and is slightly greater than the averaged estimated k(p) of 0.229 m2/g from measured opacity. The discrepancy may be partly due to a difference in the microstructure of the fly ash from the assumption of solid spheres because the fly ash may have been formed as spheres attached with smaller particles or as hollow spheres that contained solid spheres. Previously reported values of measured k(p) obtained without considering the effects of water moisture are greater than that obtained in this study, which is reasonable because it reflects the effect of extinction by water moisture in the flue gas. Additionally, the moisture absorbed by particulate matter, corresponding to the effect of water moisture on the particulates, was clarified and found to be negligible.     

An assessment of operations of oil-exporting countries in terms of energy consumption and carbon dioxide emissions

Energy consumption and carbon dioxide emissions from 16 oil-exporting countries are studied using Data Envelopment Analysis using indicators representing economic growth, energy consumption and emissions. The analysis for 1996 shows that Norway, Gabon and Nigeria are efficient and that Russia is inefficient. Malmquist Productivity Index analysis shows that there is progress in achieving higher values of GDP and non-fossil fuel consumption and in achieving lower values of fossil fuel consumption and carbon emissions in the year 1996 when compared with 1992 for Norway, Russia, Mexico, Algeria, Libya, Gabon and Oman.     

The role of multiple regression and exploratory data analysis in the development of leukemia incidence risk models for comparison of radionuclide air stack emissions from nuclear and coal power industries

Risks associated with power generation must be identified to make intelligent choices between alternate power technologies. Radionuclide air stack emissions for a single coal plant and a single nuclear plant are used to compute the single plant leukemia incidence risk and total industry leukemia incidence risk. Leukemia incidence is the response variable as a function of radionuclide bone dose for the six proposed dose response curves considered. During normal operation a coal plant has higher radionuclide emissions than a nuclear plant and the coal industry has a higher leukaemia incidence risk than the nuclear industry, unless a nuclear accident occurs. Variation of nuclear accident size allows quantification of the impact of accidents on the total industry leukemia incidence risk comparison. The leukemia incidence risk is quantified as the number of accidents of a given size for the nuclear industry leukemia incidence risk to equal the coal industry leukemia incidence risk. The general linear model is used to develop equations that relate the accident frequency required for equal industry risks to the magnitude of the nuclear emission. Exploratory data analysis revealed that the relationship between the natural log of accident number versus the natural log of accident size is linear.     

An operational assessment of the application of the relative reduction factors in the demonstration of attainment of the 8-hr ozone National Ambient Air Quality Standard

The U.S. Environmental Protection Agency in 1997 revised the 1-hr ozone (O3) National Ambient Air Quality Standard (NAAQS) to one based on an 8-hr average, resulting in potential nonattainment status for substantial portions of the eastern United States. The regulatory process provides for the development of a state implementation plan that includes a demonstration that the projected future O3 concentrations will be at or below the NAAQS based on photochemical modeling and analytical techniques. In this study, four photochemical modeling systems, based on two photochemical models, Community Model for Air Quality and the Comprehensive Air Quality Model with extensions, and two emissions processing models, Sparse Matrix Optimization Kernel for Emissions and Emissions Modeling System, were applied to the eastern United States, with emphasis on the northeastern Ozone Transport Region in terms of their response to oxides of nitrogen and volatile organic carbon-focused controls on the estimated design values. With the 8-hr O3 NAAQS set as a bright-line test, it was found that a given area could be termed as being in or out of attainment of the NAAQS depending upon the modeling system. This suggests the need to provide an estimate of model-to-model uncertainty in the relative reduction factor (RRF) for a better understanding of the uncertainty in projecting the status of an area's attainment. Results indicate that the model-to-model differences considered in this study introduce     

Changes in levels of essential elements in suckling rats exposed to zinc and mercury

The effect of mercury and its interaction with zinc on the content of essential metals in tissues from neonate rats was investigated. Three-day-old Wistar rats were treated with saline or 27 mg kg(-1)d(-1) ZnCl2 (s.c.) for five consecutive days. From the 8th to the 12th day of life, the rats received one daily dose of saline or 5.0 mg kg(-1) HgCl2 (s.c). Twenty-four hours after the last injection liver, kidneys and blood were collected for metal quantification. The HgCl(2) exposure induced alterations on metal levels, such as increase of Fe, Hg and Zn in liver, decrease of Fe and Mg and increase of Cu and Hg contents in kidneys. The Hg exposure also increased Hg levels in the blood. The treatment with ZnCl2, administered previously to HgCl2, partially prevented the increase of Fe in the liver, and not only prevented the decrease of renal Mg but also increased it to levels higher than those found in control group. The Zn-Hg rats also presented higher renal Cu levels, and showed partially lower blood and hepatic Hg levels and higher renal Hg levels. The pre-administration of Zn caused no severe alterations in levels of essential metals (Cu, Fe, Mg and Mn). In short, Zn appears to be an alternative treatment of Hg poisoning in young animals in comparison to chelating drugs since these have low metal selectivity.     

The sensitivity of the CHIMERE model to emissions reduction scenarios on air quality in Northern Italy

The sensitivity of the CHIMERE model to emission reduction scenarios on particulate matter PM2.5 and ozone (O₃) in Northern Italy is studied. The emissions of NO_x, PM2.5 SO₂, VOC or NH₃ were reduced by 50% for different source sectors for the Lombardy region, together with 5 additional scenarios to estimate the effect of local measures on improving the air quality for the Po valley area. Firstly, we evaluate the model performance by comparing calculated surface aerosol concentrations for the standard case (no emission reductions) with observations for January and June 2005. Calculated monthly mean PM10 concentrations are in general underestimated. For June, modelled PM10 concentrations slightly overestimate the measurements. Calculated monthly mean SO₄, NO₃^?, NH₄⁺ concentrations are in good agreement with the observations for January and June. Secondly, the model sensitivity of emission reduction scenarios on PM2.5 and O₃ calculated concentrations for the Po valley area is evaluated. The most effective scenarios to abate PM2.5 concentration are based on the SNAP2 (non-industrial combustion plants) and SNAP7 (road traffic) sectors, for which the NO_x and PM2.5 emissions are reduced by 50%. The number of days that the 2015 PM2.5 limit value of 25 μg m^?3 in Milan is exceeded by reducing primary PM2.5 and NO_x emissions for SNAP2 and 7 by 50%, does not change in January when compared to the standard case for the Milan area. It appears that 40% of the PM2.5 concentration in the greater Milan area is caused by the emissions surrounding the Lombardy region and from the model boundary conditions.This study also showed that a more effective pollutant reduction (emissions) per ton of pollutant reduced (concentrations) for the greater Milan area is obtained by reducing the primary PM2.5 emissions for SNAP7 by 50%. The most effective scenario on PM2.5 decrease for which precursor emissions are reduced is achieved by reducing SO₂ emissions by 50% for SNAP7.Our study showed that during summer time, the largest reductions in O₃ concentrations are achieved for SNAP7 emission reductions, when volatile organic compounds (VOCs) are reduced by 50%.     

Effects of airborne fluoride emissions near an aluminium works in Wales: part 2--saxicolous lichens growing on rocks and walls

Effects of fluoride (F(-)) emissions on previously unpolluted assemblages of saxicolous lichens, near an aluminium reduction works, are described. Lichens contained a mean 16 microg F(-) g(-1) dry weight in 1970 before emissions commenced. Subsequently, where annually monitored Ramalina contained >100microg g(-1) severe damage occurred, including loss of attachment to the rocky substratum. At sites within 1 km of the works well-exposed to emissions, fruticose (shrubby) lichens were eliminated, but in more sheltered locations 18% cover had survived by 1983. Some foliose (leaf-like) lichens tolerated >200 microg g(-1), while crustose (crust-like) species were least affected, 32% and 70% surviving, respectively. Concentrations of fluoride, and associated injury, decreased with increasing distance from the works. Fruticose and sensitive foliose species sustained 40-75% losses of cover up to 4 km NE, downwind of the works, where fluoride averaged 50-100 microg g(-1), but <40% losses were recorded in fruticose species up to 9 km, where concentrations averaged 35-50 microg. Saxicolous lichens were damaged less than corticolous species previously reported and, following decreased emissions, were also regrowing in sheltered and more distant locations by 1985.     

First-order sensitivity analysis of models with time-dependent parameters: an application to PAN and ozone

A major limitation of the decoupled direct method for local sensitivity analysis (Dunker, 1984, Journal of Chemical Physics 81; 2385–2393; Gao, 1995, Ph.D. Thesis, University of Connecticut; McCroskey and McRae, 1987, Documentation for the direct decoupled sensitivity analysis method-DDM, Pittsburgh, PA) has been its restriction to the calculation of sensitivity coefficients for constant rate parameters. Realistic atmospheric simulations require that the rate parameters in chemical mechanisms, especially photolysis rate parameters and rate parameters strongly affected by temperature variations, vary diurnally during a simulation. For this reason a new conceptual framework has been devised where time-dependent rate parameters are expressed as products of time-varying profiles and time-independent multipliers. For computational convenience the nominal values of the time-independent multipliers are chosen to be unity. According to the new procedure the decoupled direct method is used to calculate the derivatives of the concentrations with respect to each time-independent multiplier. These derivatives represent the sensitivity of the concentrations to the time-varying profiles of the time-dependent rate parameters. Local sensitivity coefficients for O₃ and PAN were calculated for a moderately polluted scenario that was free of clouds and at a constant temperature using the Regional Atmospheric Chemistry Mechanism (RACM) (Stockwell et al., 1997, Journal of Geophysical Research 102, 25,847–25,879). Calculations were compared for simulations with constant as well as diurnally changing photolysis rate coefficients. The results show that sensitivity coefficients calculated using constant, average, rate parameter values may be significantly different from sensitivity coefficients calculated using time-varying rate parameters and therefore the relative importance of the mechanism's reactions may be different for the two calculations. The greatest differences in sensitivity coefficients were found for reactions with rates that have strong diurnal variations, such as photolysis, HO and NO₃ reactions. It was further found that diurnally varying reactions have cumulative effects on sensitivity coefficients during the simulation of an episode that are not present when constant rate parameters are used. These results have implications, not only for sensitivity analysis and modelling, but also for the use of measurements to validate chemical models.     

The use of olive-mill waste compost to promote the plant vegetation cover in a trace-element-contaminated soil

The applicability of a mature compost as a soil amendment to promote the growth of native species for the phytorestoration of a mine-affected soil from a semi-arid area (SE Spain), contaminated with trace elements (As, Cd, Cu, Mn, Pb and Zn), was evaluated in a 2-year field experiment. The effects of an inorganic fertiliser were also determined for comparison. Bituminaria bituminosa was the selected native plant since it is a leguminous species adapted to the particular local pedoclimatic conditions. Compost addition increased total organic-C concentrations in soil with respect to the control and fertiliser treatments, maintained elevated available P concentrations throughout the duration of the experiment and stimulated soil microbial biomass, while trace elements extractability in the soil was rather low due to the calcareous nature of the soil and almost unaltered in the different treatments. Tissue concentrations of P and K in B. bituminosa increased after the addition of compost, associated with growth stimulation. Leaf Cu concentration was also increased by the amendments, although overall the trace elements concentrations can be considered non-toxic. In addition, the spontaneous colonisation of the plots by a total of 29 species of 15 different families at the end of the experiment produced a greater vegetation cover, especially in plots amended with compost. Therefore, the use of compost as a soil amendment appears to be useful for the promotion of a vegetation cover and the phytostabilisation of moderately contaminated soils under semi-arid conditions.     

An assessment of the aggregate impacts of the proposed reduction in the motor fuels tax in the United States

The analysis in this paper examines the impact of reducing the excise tax on gasoline and diesel fuel on the United States economy. The analytical approach used consists of a computable general equilibrium model composed of fourteen producing sectors, fourteen consuming sectors, six household categories classified by income and the government. The effects of a 4.3 cents per gallon reduction in the excise tax on gasoline and diesel fuel on prices and quantities are examined. The results suggest, for example, that a decrease in the tax would result in higher output by the producing sectors (by about $2.86 billion), and expansion in the consumption of goods and services (by about $3.48 billion), and an increase in welfare (by about $3.59 billion). The government would realise a decrease in revenue of about $2.37 billion. When subjected to a sensitivity analysis, the results are reasonably robust with regard to the assumption of the values of the substitution elasticities.     

An assessment of the risks associated with PCDDs and PCDFs following the application of sewage sludge to agricultural land in the UK

A model has been developed to describe the transfer of PCDDs and PCDFs from sludge-amended soils to the human foodchain. The model is conservative and assumes that all foods consumed by an individual are derived from sludge-amended soils. Predicted concentrations of PCDDs and PCDFs in potatoes, cereals, root vegetables and leafy vegetables were in close agreement with mean concentrations reported in the food survey conducted by MAFF in the UK. Predicted concentrations in milk were well below the Maximum Tolerable Concentration adopted by MAFF. Assuming a half-life of ten years in sludge-amended soils, the maximum estimated incremental daily intake (IDI) predicted by the model following ten applications of sludge to agricultural land was 0.80 pg I-TEQ kg⁻¹ day⁻¹, representing an increase of approximately 45% on current levels of background exposure. For an individual whose diet is solely derived from sludge-amended soils, the total exposure is predicted to be approximately 181 pg I-TEQ day⁻¹ or 2.6 pg I-TEQ kg⁻¹ day⁻¹. This compares with an average background exposure of approximately 2 pg I-TEQ kg⁻¹ day⁻¹, well within the TDI of 10 pg I-TEQ kg⁻¹ day⁻¹ and indicates that the application of sewage sludge to agricultural land under the conditions assumed would not appear to present a significant health risk under the conservative scenarios considered in this assessment.