Rainfall variations around a thermal power station

Rainfall data of Neyveli thermal power station and of stations within 100 km around were examined, after eliminating the secular trends for the period 1958–1974. The analysis suggested that, with respect to nearby stations in the distance range 12–25 km, rainfall at a gauge 1 km from the power station increased in the last 6 y of the period by over 25%.     

Monitoring airborne dust in a high density coal-fired power station region in North Yorkshire

Concerns about the levels of dust deposition in the vicinity of coal-fired power stations in North Yorkshire, in particular Drax Power Station, prompted the commissioning of a detailed monitoring study in the area. This paper describes the first two years' work. The first 12-month study concentrated on the village of Barlow close to Drax Power Station, whilst in the second 12-month study, monitoring sites were spread along a transect passing through the power station belt formed by Ferrybridge, Eggborough and Drax Power Stations. Two monitoring sites were common to both 12-month studies, thus giving two years of continuous monitoring. Pairs of wet Frisbee dust deposit gauges (based on inverted Frisbees) were located at each site. Undissolved particulate matter from each gauge was weighed and characterized by microscopic examination of individual particles. The first 12-month study revealed a downward gradient in dust deposition rate and cenosphere content with distance from Drax Power Station. The high cenosphere content at Barlow, especially at the eastern end, suggested that there was a significant contribution from coal-fired power stations. In the second year, the overall pattern of dust deposition rate and cenosphere content across the power station belt suggested that power stations were contributing to higher levels. In particular, relatively high levels were again found at Barlow. Wind direction correlations point to the fly-ash tip next to Drax Power Station as being the source of cenospheres arriving at Barlow. It is concluded that in both years the fly-ash tip Drax Power Station was making a significant contribution to higher than expected dust deposition rates at Barlow, particularly its eastern end. Other villages in the area may also have been affected by dust originating from coal-fired power stations.     

First assessment of dioxin emissions from coal-fired power stations in Spain

In this work, the findings of the first assessment of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in emissions releases to the atmosphere from coal-fired power plants are given. A total of five plants were selected for the study located at different provinces in Spain. In all the cases, the results revealed very low levels, in the range of 0.41 pg I-TEQ/Nm(3). The profile indicated in the majority of the cases predominance of highly chlorinated congeners being OCDD the most important contributor. The findings were also used to estimate contribution of PCDDs/PCDFs emitted from coal-fired power plants in Spain. Individual plant results revealed values below 0.02 g I-TEQ per year and plant. Nevertheless, considering the total coal consumption in Spain in 1997, the values are comparable to those reported in other countries in the range of 0.6-0.7 g I-TEQ per year. Moreover, emission factors were determined considering operating conditions of evaluated plants. In general, large variability was observed and values below 1-5 pg I-TEQ/kg coal were early reached.     

SAGA: a decision support system for air pollution management around a coal-fired power plant

Air quality models are currently feasible approaches to prevent air pollution episodes. From one of the first source-oriented modelling approaches for air pollution forecasting (Souto et al., 1994, 1996, 1998), a new decision support system for air quality management, SAGA, was developed to provide support to As Pontes Power Plant (APPP) staff. SAGA can provide air pollution forecasts and manage meteorological and air quality measurements. Power plant decisions are supported by the results of a non-hydrostatic meteorological model (ARPS, Xue et al., 2001) to produce Meteorological Forecasts (MFs), and to be coupled to different Lagrangian dispersion models.     

A new method to assess mercury emissions: a study of three coal-fired electric-generating power station configurations

U.S. Environmental Protection Agency (EPA) Method 7473 for the analysis of mercury (Hg) by thermal decomposition, amalgamation, and atomic absorption spectroscopy has proved successful for use in Hg assessment at coal-fired power stations. In an analysis time of approximately 5 min per sample, this instrumental methodology can directly analyze total Hg--with no discrete sample preparation--in the solid matrices associated with a coal-fired power plant, including coal, fly ash, bottom ash, and flue gas desulfurization (FGD) material. This analysis technique was used to investigate Hg capture by coal combustion byproducts (CCBs) in three different coal-fired power plant configurations. Hg capture and associated emissions were estimated by partial mass balance. The station equipped with an FGD system demonstrated 68% capture on FGD material and an emissions estimate of 18% (11 kg/yr) of total Hg input. The power plant equipped with low oxides of nitrogen burners and an electrostatic precipitator (ESP) retained 43% on the fly ash and emitted 57% (51 kg/yr). The station equipped with conventional burners and an ESP retained less than 1% on the fly ash, emitting an estimated 99% (88 kg/yr) of Hg. Estimated Hg emissions demonstrate good agreement with EPA data for the power stations investigated.     

Characterization and sources assignation of PM2.5 organic aerosol in a rural area of Spain

The results from a year-long study of the organic composition of PM2.5 aerosol collected in a rural area influenced by a highway of Spain are reported. The lack of prior information related to the organic composition of PM2.5 aerosol in Spain, concretely in rural areas, led definition of the goals of this study. As a result, this work has been able to characterize the main organic components of atmospheric aerosols, including several compounds of SOA, and has conducted a multivariate analysis in order to assign sources of particulate matter. A total of 89 samples were taken between April 2004 and April 2005 using a high-volume sampler. Features and abundance of n-alkanes, polycyclic aromatic hydrocarbons (PAHs), alcohols and acids were separately determined using gas chromatography/mass spectrometry and high performance liquid chromatography analysis. The Σn-alkane and ΣPAHs ranged from 3 to 81 ng m^?3 and 0.1 to 6 ng m^?3 respectively, with higher concentrations during colder months. Ambient concentrations of Σalcohols and Σacids ranged from 21 to 184 ng m^?3 and 39 to 733 ng m^?3, respectively. Also, several components of secondary organic aerosol have been quantified, confirming the biogenic contribution to ambient aerosol. In addition, factor analysis was used to reveal origin of organic compounds associated to particulate matter. Eight factors were extracted accounting more than 83% of the variability in the original data. These factors were assigned to a typical high pollution episode by anthropogenic particles, crustal material, plant waxes, fossil fuel combustion, temperature, microbiological emissions, SOA and dispersion of pollutants by wind action. Finally, a cluster analysis was used to compare the organic composition between the four seasons.     

内蒙古某电厂周围土壤汞分布特征及其影响因素

研究内蒙古草原两燃煤电厂附近土壤中汞含量分布特征及其与土壤性质的关系.结果表明,48.15%的供试土壤汞含量超出当地土壤汞含量背景上限值,且距电厂越近,汞含量越高.距电厂较远、受污染较小地区的土壤汞含量与土壤理化性质密切相关:土壤pH8.0时,趋势相反;土壤有机质与汞含量呈现出正相关性;土壤颗粒越细,对汞的吸附能力越强,汞含量越高,但当颗粒细至粘粒时,随着粘粒含量的增多,汞含量呈现出减少的趋势.     

Trace element concentrations in lichens near a coal-fired power plant

Samples of two different species of lichens (Parmelia caperata and Parmelia rudecta) were analyzed by instrumental neutron activation analysis (INAA) to determine the concentrations of trace elements. The relation between atmospheric concentrations of elements borne by particles and composition patterns in lichens are examined by calculating enrichment factors (EF). The lichens collect material from the atmosphere to which they have been exposed. However, they collect preferentially larger particles, which are probably deposited by impaction and/or dry deposition, but not rain or filtration. No significant differences in concentrations were observed among lichens collected at various distances ranging from 1.6 to 20 km from the plant, suggesting that the effects of plume touchdown are small compared with normal ambient concentrations of particles.     

Reconstructing historical trends of polycyclic aromatic hydrocarbon deposition in a remote area of Spain using herbarium moss material

Herbarium mosses from 1879–1881, 1973–1975 and 2006–2007 were used to investigate the historical changes of atmospheric deposition of polycyclic aromatic hydrocarbons (PAHs) at a remote site in Northern Spain. Natural abundance of nitrogen and carbon isotopes was also measured in order to assess the evolution of emissions from anthropogenic sources. Nitrogen and PAH concentrations as well as δ¹³C and δ¹⁵N ratios were significantly higher in 19th century samples compared to present century samples. Moreover, PAH distribution varied over the centuries, with the trend towards enrichment in light PAHs. The carbon, nitrogen and PAH concentrations measured in the mosses tally with the historical evolution of anthropogenic emissions in the area, mainly influenced by changes in economic activities, domestic heating and road traffic density. Mosses provided by herbaria seem to offer the possibility of studying long-term temporal evolution of atmospheric PAH deposition.     

Influence of meteorological factors and polluting environment on rain chemistry and wet deposition in a rural area near Chimay,Belgium

This paper focuses on a detailed analysis of the effects of meteorological factors explaining the variability of rain composition.Inorganic composition of 113 individual rain events was measured from May 2002 to October 2005 at a rural site near Chimay, in the western part of the Belgian Ardennes. Original models were fitted for each studied ion (H⁺, Mg²⁺, Ca²⁺, K⁺, NH₄⁺, Na⁺, Cl⁻, NO₃⁻ and SO₄²⁻) to relate rain event concentration or wet deposition to the rainfall volume (R), the length of the antecedent dry period (ADP), the volume of the previous event (R_prev) as well as to the mean wind speed and the prevailing wind direction during both the dry and the rainy periods. These variables explained from 32% (H⁺) to 69% (NO₃⁻) of rain concentration variability. Concentrations decreased logarithmically with increasing R values except in case of H⁺ for which a positive effect of rain volume on rain concentration was observed. ADP affected positively rain concentrations of all ions excluding K⁺ and H⁺ for which, respectively, a nonsignificant and a negative effect of this variable was observed. Increasing R_prev strengthened the effect of the variable R on H⁺, Mg²⁺, Ca²⁺, Na⁺, NH₄⁺ and SO₄²⁻ concentrations while it softened the effect of ADP on NO₃⁻ concentrations. Wind speed and direction during dry and rainy periods explained together from 8% (K⁺) to 38% (Na⁺) of rain concentration total variability. R² coefficients of the wet deposition models ranged from 0.51 (K⁺) to 0.79 (SO₄²⁻). For all ions, wet deposition increased significantly with increasing R values while the effects of the other variables were similar to those on concentrations. Wind conditions during dry and rainy periods explained from 4% (H⁺) to 24% (Na⁺) of wet deposition total variability. On an annual scale, the total dry period duration, the total rainfall volume as well as the shape of the distributions of the length of the antecedent dry periods and of the rain event volume are important parameters that influence annual wet deposition.     

The contribution of sedimentation to aerosol deposition to vegetation with a large leaf area index

The deposition to vegetative canopies of aerosols of dia. 30 μm and less generally increases with wind speed. This phenomenon is due in part to deposition by impaction, but is also due to more sedimentation to lower leaves of the canopy as a result of enhanced turbulent mixing of the air amongst the foliage. A physical model of deposition by sedimentation alone is derived which shows how the deposition velocity, v_g, would be expected to vary with wind speed in the absence of deposition by impaction. The results are compared with experimental observations of deposition of Lycopodium powder to dry and wet vegetation (Chamberlain and Chadwick, 1972). The comparison suggests that for wet vegetation in high wind speeds impaction is a major cause of deposition; but for dry vegetation and for wet vegetation in moderate wind speeds, the rise in v_g may be caused mainly by increased sedimentation to lower leaves.     

Effect of coal-fired power generation on visibility in a nearby national park

The Mohave coal-fired power plant has long been considered a major contributor to visibility impairment in Grand Canyon National Park. The permanent closure of the plant in 2005 provides the opportunity to test this assertion. Although this analysis, based on data from the Interagency Monitoring of Protected Environments (IMPROVE) Aerosol Network, shows that fine sulfate levels in the park dropped following the closure, no statistically significant improvement in visibility resulted. Difference-in-differences estimation was used to control for other influences. This finding has important implications for the methods generally employed to attribute visibility reductions to air pollution sources.     

燃煤电站湿法烟气脱硫的颗粒物脱除效果

伴随着我国燃煤电站污染物严峻形势,湿法烟气脱硫协同捕集颗粒物越来越受到工程应用部门的重视。从基本理论出发,引入捕集体与颗粒碰撞、拦截与扩散的基本方程,推导并建立多液滴对多颗粒的捕集模型。研究结果表明：直径245 μm的液滴,沉降速度小于气流速度,会被携带出脱硫塔;液滴对PM0.1、PM1、PM2.5、PM5、PM10颗粒物的去除效率为U型曲线,910 μm液滴对颗粒物的去除效率比4 666 μm液滴高近百倍;同等质量浓度,不同粒度分布,脱硫塔除尘性能仍然差异较大。     

Accumulation of potentially toxic trace elements (PTEs) by native plant species growing in a typical gold mining area located in the northeast of Qinghai-Tibet Plateau

Environmental Science and Pollution Research - Though gold mines provide significant economic benefits to local governments, mining causes soil pollution by potentially toxic trace elements (PTEs)...     

Assessing the enrichment of heavy metals in surface soil and plant (Digitaria eriantha) around coal-fired power plants in South Africa

Nine metals (Fe, Cu, Mn, Ni, Cd, Pb, Hg, Cr, and Zn) were determined in soil and Digitaria eriantha plants within the vicinity of three coal power plants (Matla, Lethabo, and Rooiwal), using ICP-OES and GFAAS. The total metal concentration in soil ranged from 0.05?±?0.02 to 1836?±?70 μg g^?1, 0.08?±?0.05 to 1744?±?29 μg g^?1, and 0.07?±?0.04 to 1735?±?91 μg g^?1 in Matla, Lethabo, and Rooiwal, respectively. Total metal concentration in the plant (D. eriantha) ranged from 0.005?±?0.003 to 535?±?43 μg g^?1 in Matla, 0.002?±?0.001 to 400?±?269 μg g^?1 in Lethabo, and 0.002?±?0.001 to 4277?±?201 μg g^?1 in Rooiwal. Accumulation factors (A) of less than 1 (i.e., 0.003 to 0.37) at all power plants indicate a low transfer of metal from soil to plant (excluder). Enrichment factor values obtained (2.4–5.0) indicate that the soils are moderately enriched with the exception of Pb that had significant enrichment of 20. Geo-accumulation index (I-geo) values of metals indicate that the soils are moderately polluted (0.005–0.65), except for Pb that showed moderate to strong pollution (1.74–2.53).     

Moss (Bryum radiculosum) as a bioindicator of trace metal deposition around an industrialised area in Sardinia (Italy)

The moss Bryum radiculosum (Brid.), a species typical of dry and coastal environments, was used as a bioindicator for the estimation of atmospheric trace metal deposition around the industrial site of Portoscuso (Sardinia, Italy), which includes a lead-zinc smelter, two power plants, and aluminium production factories. For Cd, Pb, Zn, and V the results showed very similar patterns with extremely high values in the immediate surroundings of the industrial area. Copper and Cr showed somewhat different patterns, but still pointing to local pollution sources. The levels of metals at distance of about 13 km from the industrial site were still higher than in background samples. In order to evaluate the suitability of B. radiculosum for monitoring studies, trace metal concentrations in moss were compared with bulk deposition measurements in the same area. Correlation was significant only for Pb, Cd, and Zn. For Cr, Cu, and V the results showed high variability, mainly to be ascribed to soil factors.     

Predictions of U.K. regulated power station contributions to regional air pollution and deposition: a model comparison exercise

Contributions of the emissions from a U.K. regulated fossil-fuel power station to regional air pollution and deposition are estimated using four air quality modeling systems for the year 2003. The modeling systems vary in complexity and emphasis in the way they treat atmospheric and chemical processes, and include the Community Multiscale Air Quality (CMAQ) modeling system in its versions 4.6 and 4.7, a nested modeling system that combines long- and short-range impacts (referred to as TRACK-ADMS [Trajectory Model with Atmospheric Chemical Kinetics-Atmospheric Dispersion Modelling System]), and the Fine Resolution Atmospheric Multi-pollutant Exchange (FRAME) model. An evaluation of the baseline calculations against U.K. monitoring network data is performed. The CMAQ modeling system version 4.6 data set is selected as the reference data set for the model footprint comparison. The annual mean air concentration and total deposition footprints are summarized for each modeling system. The footprints of the power station emissions can account for a significant fraction of the local impacts for some species (e.g., more than 50% for SO2 air concentration and non-sea-salt sulfur deposition close to the source) for 2003. The spatial correlation and the coefficient of variation of the root mean square error (CVRMSE) are calculated between each model footprint and that calculated by the CMAQ modeling system version 4.6. The correlation coefficient quantifies model agreement in terms of spatial patterns, and the CVRMSE measures the magnitude of the difference between model footprints. Possible reasons for the differences between model results are discussed. Finally, implications and recommendations for the regulatory assessment of the impact of major industrial sources using regional air quality modeling systems are discussed in the light of results from this case study.     

Ozone concentrations at a high altitude station in the Central Massif (Spain)

In order to contribute to current knowledge of ozone concentrations and transport across the Central Massif, a monitoring station was installed at 1780 m on the upper Spanish plateau about 55 km from the city of Madrid. Ozone concentrations and standard meteorological variables were measured in June and July 2002. A smoothed ozone hourly cycle was obtained with mean values of 120 and 110 microgm(-3) during day-time and night-time, respectively. The highest ozone concentrations were recorded in the SE-S-SW wind sectors, proving the influence of transport from the Madrid urban plume to the upper plateau. This assumption was also supported by the satisfactory correlation between ozone peaks obtained at the monitoring site and those recorded in a representative station on the foothill located on the lower plateau during episodic situations. To assess the contribution of long-range transport, backward air mass trajectories were computed each day of measurements at 820 hPa. The lowest ozone mean was linked to Atlantic Ocean air masses, and the highest to air masses from Central Europe.     

Occurrence of nitro-pah in the atmosphere in a rural area

By means of gas chromatography with nitrogen sensitive detection and negative ion chemical ionization mass spectrometric detection 7 mononitro-PAH, 9-nitroanthracene, x-nitro-4,5-methylene-phenanthrene, 3-nitrofluoranthene, 1- and 2-nitropyrene, 10-nitrobenz(a)anthracene and 6-nitrobenzo-(a)pyrene have been identied in samples of airborne particulate matter. Furthermore, 8-nitrofluoranthene has been tentatively identified. The amounts of mononitro-PAH are one to two orders of magnitude lower than the most common carcinogenic PAH, as e.g. benzo(a)pyrene. Filter effects have been studied, 9-nitroanthracene can be transformed during sampling at low atmospheric concentrations of NO₂ and photochemical oxidants to 9,10-dinitroanthracene and 10-nitroanthrone.