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The transition from limestone to lime-based flue gas desulphurisation system (FGD) was tested in a power station fired with high sulphur (S)-petroleum coke to better control the emissions of key pollutants. To this end, as a request of the power station owner to IDÆA-CSIC, we surveyed the power station fired with 70% S-petroleum coke and equipped with a slaked lime-based FGD, and compared the results with data from our previous works conducted at the same power station but operated with lower co-firing rates and a limestone FGD, the purpose being to improve the understanding on the impact that different FGD technologies may have on the fate, speciation and, ultimately, the emissions of key pollutants from the power station. Our observations suggest that the reaction pathways and speciation of key trace pollutants in the gypsum slurry including Cl, Mo, Hg and Se remained largely unchanged with the transition from limestone to lime-based FGD. By contrast, As, Cr, B, U and V speciation in the gypsum slurry was sensitive not only to the FGD sorbent, likely in response to differences in the pH, but also to the absence of ligands such as F−.The highly alkaline lime slurry neutralised the H+ released by the formation of metal-complexes. This favoured the stability of trace elements in their oxy-anionic forms or forming hydroxyl complexes, as opposed to the acidic conditions in limestone-FGD gypsum from previous works. Enrichment in Mo, V and Ni in the fly ash was primarily associated with the combustion of a petroleum coke. Other elements such as Pb, As, Zn, Cu and Se were also enriched in the fly ash relative to the boiler slag. • The use of slaked lime is a promising alternative for limestone flue gas desulphurisation (FGD). • The speciation of Cl, Mo, Hg and Se remained unchanged with the transition to lime-based FGD. • As, Cr, B, U and V speciation was sensitive to response to differences in pH and absence of ligands such as F−. • The alkaline conditions favoured the stability of trace elements in their oxyanionic forms or forming hydroxyl complexes. • The replacement of lime may benefit the power plant as hydroxide and other ionic complexes offer more manageable options. [ABSTRACT FROM AUTHOR]

Coal fly ash (FA) is an abundant commodity in many countries using steam coal for power production. In some countries (e.g. Israel) all the FA is utilized whereas in some countries only low percentage is used (e.g. USA). The main mode of utilization is in the civil engineering industries as cement or clinker additive or for concrete production. In Israel (2014) 1.3 Mt of highly basic type F FA has been produced, mostly from South African and Colombian coals, in the utilities. A potential application for type F FA could be as an efficient scrubber for hazardous acidic wastes (e.g. the phosphate industry). The scrubbing efficiency of FA stems from interactions of the aluminosilicate surface of the particles with trace elements or with fine precipitates of ionic solids (e.g. SrCO 3 ). The process changes the chemical and physical nature of the FA surface. These changes have been studied using SEM, TEM, XRD and particle size measurements of non-treated, compared to treated FA with acidic or neutral aqueous solutions. The results indicate that an appreciable part of the outer lime layer and part of the glassy aluminosilicate material is dissolved, revealing the mullite skeleton as well as Ti, and Fe species. Moreover, formation of mixed ettringite/thaumasite and halite particles is observed. Thus, this study can lead to a better understanding of the fixation mechanisms of the trace elements by coal FA. [ABSTRACT FROM AUTHOR]

Abstract: Coal-based power generation produces over 750Mt of coal ash per year globally, but under 50% of world production is utilised. Large amounts of fly ash are either stored temporarily in stockpiles, disposed of in ash landfills or lagooned. Coal ash is viewed as a major potential source of release of many environmentally sensitive elements to the environment. This paper encompasses over 90 publications on coal fly ash and demonstrates that a large number of elements are tightly bound to fly ash and may not be easily released to the environment, regardless of the nature of the ash. This review provides an extensive look at the extent to which major and trace elements are leached from coal fly ash. It also gives an insight into the factors underlying the leachability of elements and addresses the causes of the mobility. The mode of occurrence of a given element in the parent coal was found to play an important role in the leaching behaviour of fly ash. The amount of calcium in fly ash exerts a dominant influence on the pH of the ash–water system. The mobility of most elements contained in ash is markedly pH sensitive. The alkalinity of fly ash attenuates the release of a large number of elements of concern such as Cd, Co, Cu, Hg, Ni, Pb, Sn or Zn among others, but at the same time, it enhances the release of oxyanionic species such as As, B, Cr, Mo, Sb, Se, V and W. The precipitation of secondary phases such as ettringite may capture and bind several pollutants such ash As, B, Cr, Sb, Se and V. [Copyright &y& Elsevier]

Abstract: Simultaneous measurements of the PM concentration levels and chemical composition of atmospheric aerosols at a regional background (RB) and an urban background (UB) site, located in the same geographic region, allowed for the determination of their urban and regional contributions. In the specific case of the North-Western region of the Mediterranean the RB amount has been quantified in 18, 13 and 12 μg m−3 for PM10, PM2.5 and PM1, respectively, whereas the UB contribution reached 22, 13 and 8 μg m−3, respectively. The UB contributions in the Western Mediterranean are much higher than those observed in other European regions; especially concerning the coarse fraction. The high loads of road dust in the urban areas across the Mediterranean may account for these large differences. The urban contributions are extremely enriched in Ca, Fe, Sb, Sn, Cu, Zn, being the main tracers of the road dust, with concentrations up to 6–8 times higher than those at the RB. Elemental carbon and nitrate are mainly derived from direct vehicular emissions. Some industrial tracers (Mn, Pb, Bi) are also enriched in the urban area. The evaluation of the Cu/Sb, Cu/Zn, Cu/Cd and Cu/Pb ratios and the high enrichment of these trace elements versus the Upper Crustal Composition average values corroborates the importance of the road-traffic emissions in the study area, also influencing the RB. The supplementary results from a suburban site in the Balearic Islands and the evaluation of the V/Ni ratios evidence the strong signature of fuel-oil combustion processes, which is a general characteristic of the Mediterranean aerosols. [Copyright &y& Elsevier]

Abstract: The insular suburban site of Castillo de Bellver was selected for the study of the variability of PM levels and composition in the Western Mediterranean Basin (WMB). Mean annual (in 2004) PM10 and PM2.5 levels at this site were 29 and 20µg/m3, respectively. These levels may be regarded as relatively low when compared with other suburban insular locations in the Eastern Mediterranean Basin (EMB), but they are higher than those recorded at most of the European suburban sites, especially in Northern and Western Europe. Seasonal variability of PM levels at this site is governed by meteorology rather than local emissions, whereas the daily cycles are clearly defined by the anthropogenic emissions, mainly coming from the urban area of Palma de Mallorca and the harbour area of the same city. Concerning the aerosol composition at this site, the main PM constituent is the mineral matter (29% in PM10 and 16 % in PM2.5), more than 50% (in PM10) being attributable to African dust. The amount of secondary inorganic aerosols is also very high (27% in PM10 and 34% in PM2.5), with the predominance of fine ammonium sulphate, and in a less proportion fine ammonium nitrate (in winter) and coarse Ca and Na nitrate (with higher importance in summer). The carbonaceous particles, dominantly fine, account for 17% of PM10 and 25% of PM2.5. The elemental carbon/organic carbon (EC/OC) ratio reached a mean value of 0.17, similar to those observed at regional background sites in the WMB coast of Spain. The sea spray aerosols (mainly coarse) represented around 10% of PM10, and only 4% in PM2.5. Finally, the unaccounted fraction increased from 15% to 20% in PM2.5, being mostly attributed to water. The concentrations of trace elements in PM10 and PM2.5 were usually in the range to those observed in regional background sites in the Iberian Peninsula, with the exception of the typical tracers of road traffic such as Cu, Sb, Zn, Sn and Ba, which presented concentrations in the range of urban sites of Iberia. Other elements such as Cr, Zr, Hf and Co have been identified as the main tracers of the harbour contributions. [Copyright &y& Elsevier]

This study deals with the use of fly ash as a starting material for geopolymeric matrices. The leachable concentrations of geopolymers were compared with those of the starting fly ash to evaluate the retention of potentially harmful elements within the geopolymer matrix. Geopolymer matrices give rise to a leaching scenario characterised by a highly alkaline environment, which inhibits the leaching of heavy metals but may enhance the mobilization of certain oxyanionic species. Thus, fly ash-based geopolymers were found to immobilise a number of trace pollutants such as Be, Bi, Cd, Co, Cr, Cu, Nb, Ni, Pb, Sn, Th, U, Y, Zr and rare earth elements. However, the leachable levels of elements occurring in their oxyanionic form such as As, B, Mo, Se, V and W were increased after geopolymerization. This suggests that an optimal dosage, synthesis and curing conditions are essential in order to obtain a long-term stable final product that ensures an efficient physical encapsulation. [Copyright &y& Elsevier]

Abstract: The speciation of Ga, Ge, Ni, V, S and Fe in fly ash from IGCC power plant were investigated for possible further extraction process by combining conventional mineral and chemical analysis, leaching tests, wet sequential extraction, Mössbauer and XAFS spectroscopies. The results shown that Ge occurs mainly as water-soluble species, GeS and/or GeS2 and hexagonal GeO2. Ga is present as an oxide, Ni occurs mainly as nickeline (NiAs), with minor proportions of Ni arsenates and vanadium as V(III) with minor amounts of V(IV) in the aluminosilicate glass matrix. Pyrrhotite and wurtzite-sphalerite are sulfide species containing Fe and Zn, but an important fraction of iron is also present in the aluminosilicate glass. These clear differences between the speciation of the above elements in this material and those reported for fly ash from conventional PC combustion. [Copyright &y& Elsevier]

Elemental composition and mineralogy of a high ash feed coal (ash: 49.7 wt.%), and its bottom and fly ash from a Brazilian power plant (Presidente Médici Power Plant or UTPM-446 MW) was determined using ICP-MS, ICP-AES, X-ray diffraction (XRD) and scanning electron micrography (SEM). Most trace elements in coal fall in the usual range determined for world coals. However, concentrations of some elements were higher than the expected for coals, including Cs Rb and heavy rare earth elements (REEs). This might be due to the high content of detrital minerals of the studied coal, given that these elements are usually associated with clay minerals. Elements were classified into three groups based on the analysis of trace element concentrations in fly and bottom ashes, and enrichments or depletions of these concentrations in relation to the coal: Group I (volatile elements with subsequent condensation): As, B, Bi, Cd, Ga, Ge, Mo, Pb, S, Sb, Sn, Tl and Zn; Group II (no volatile elements enriched in bottom ash vs. fly ash): Ca, Fe, Mn, P, Ti and Zr; Group III (low volatile elements with no partitioning between fly and bottom ashes): Al, Ba, Be, Co, Cr, Cs, Hf, K, Li, Mg, Na, Ni, Rb, Sr, Th, U, W, Y and most of REE. The mass balance for trace elements obtained demonstrated that the volatile emission of the trace elements studied is very low. According to the leachable proportion obtained, the elements may be classified as follows: B (40–50%)>Mo>Cu>Ge=Li=Zn=As>, Ni, Sb, Tl, U>Ba, Cd, Sr, V (0.3–2%). For the other elements studied, the leachable fraction is in most cases <1% of the bulk content. [Copyright &y& Elsevier]

• Frontal brake pad wear is the primary source of Ba and Zn in PM. • Lateral brake pad wear is a source of Sb, As, Zn, Mo, Hg, and Pb in PM. • Steel wear is the main source of As, Hg, Sb, and Mo in PM when frontal brake pads are employed. • Wear processes raise PM levels and modify the speciation of metals. • Substituting conventional friction materials should reduce metal exposure. Wear in train and rail components in the Barcelona subway system includes brake pads, catenary wires, wheels, railways, and motor brushes. These components were characterised to evaluate their contribution to ambient particulate matter (PM) levels in two platforms (conventional F-L3 and new S-L9). The observed chemical compositions of these components were used to interpret the mineralogical, chemical, and leachability patterns of subway platform particulate matter (PM). The use of sulphides such as molybdenite (MoS 2), pyrite (FeS 2), stibnite Sb 2 S 3) rich in toxic elements such as in Cu, Ni, As, Hg, Cd, and Pb and abrasives such barite (BaSO 4) and zinzite (ZnO) in the brake pad composition, the composition of the catenary rich in Cu (98% metallic-Cu) with traces of Hg and that of the wheel/rail (98% metallic-Fe) with traces of As results in the production of fine PM particles of As, Hg, Cu, and Sb in ambient air PM in platform as a consequence of the abrasion/friction and sparking processes. The temperature reached in the aforementioned processes give rise to fine condensed and water-soluble As species (most likely As 2 O 3 and As 2 O 5). Moreover, the stibnite (Sb 2 S 3) Hg-rich lateral brake pads used in L9 also contribute to fine and relatively soluble Sb and Hg oxides. Sulphide-rich brake pads significantly increase and change the occurrence mode of the Zn, Cu, Mn, Cr, Pb, and Ni present in PM by oxidation of brake-bearing metal sulphide to relatively water-soluble sulphate and oxide species. These changes in the mode of occurrence and speciation of elements in the PM of subway platforms points to the need for in-depth PM speciation studies, as well as the need for substituting conventional friction materials with low-metal materials—such as graphite pantographs/catenaries and rubber wheels and low toxic sulphides in brake pads—to reduce exposure to metals during subway commuting. [ABSTRACT FROM AUTHOR]

Abstract The present study deals with the nano-mineralogy and geochemistry of ultrafine particles in construction waste from the Porto Alegre region in Southern Brazil. Uncontrolled construction waste dumps and poor management practices in formal disposal sites in the area may increase exposure risks to population. Whilst the physicochemical properties of construction wastes are well documented in the literature, the characteristics of nanoparticles in their formulations are not well known. Given that degradation of construction materials may unlock and enable further release of nano-particulates present, we focused on the <63 μm fraction to examine the geochemistry of inhalable nano-particulates that could cause adverse health impacts on local communities. A particular feature across the studied wastes are the numerous aerodynamically favourable, spherical-shaped nanoparticles of magnetite, rutile and anatase. The detected nanoparticles contained a number of elements including Al, As, Au, Ca, Cd, Co, Cr, Cu, Hg, Na, Fe, K, S, Sn, Si and. An enrichment in metals and metalloids such as As, Co, Cr, Cu, Hg, Fe, Sn or Ta in particles in the nano-scale range in relation to larger particles was observed. The presence of carbon nanotubes was also noted. The leaching tests showed that the construction wastes did not reach the limits for their disposal as hazardous waste according the European Directive. Whilst the majority of trace elements were highly immobile, the water extractability for oxyanionic-forming metalloids suggests possible migration to surface and groundwater bodies. This work seeks to bring awareness on the impacts of unsustainable construction waste management, and the relevance of improved regulations regarding their final disposal. Graphical abstract Image 10620 Highlights • Concrete, tiles and plasterboard wastes contained numerous metal-rich nanoparticles. • Spherical TiO 2 and Fe 3 O 4 nanoparticles were particularly abundant. • As, Co, Cr, Cu, Hg, Sn, Ta were enriched in nanoparticles compared to coarser sizes. • Oxyanionic species in ultrafine particles are particularly water soluble. [ABSTRACT FROM AUTHOR]

Abstract: The mineralogical and geochemical characteristics of feed coals and their combustion by-products (fly ash and slag) from Hongyanchi (HONG) and Weihuliang (WEI) coal-fired power plants in Xinjiang Province, Northwest China, were investigated. The enrichment and partitioning behaviour, as well as the leaching potential of the major and trace elements in these combustion by-products were evaluated. Three feed coals from the two power plants (HC, WC1, and WC2) were characterised by medium-moisture contents, low- to medium-ash yields, high volatile matters, and low-S contents as well as low-mineral contents. Except B, Sr, and Ba in WC1 feed coal; P, Ti, V, Cr, Mn, Cu, Zn, Rb, and Ba in WC2 feed coal; and Ti, Mn, Cu, Zn, Rb, Sr, and Ba in the HC feed coal, most major and trace element concentrations were low compared with other Chinese coals and coals worldwide. Most trace element concentrations in the studied fly ashes (HA, WAf, and WAc) were even lower than their minimum and/or 25th percentile (P25) values reported for EU fly ashes, as were the element concentrations in the fly ash leachates. The studied fly ashes were all classified as type F fly ashes, with high glass contents as well as high SiO2/Al2O3 ratios in the glass matrix. Through enrichment factors, mass balance, and partitioning of elements, S, F, Cl, Hg, and B were highly volatile in both PCC plants. Tin, As, Se, Cu, and Zn were also moderately volatile, and they were enriched in fly ashes mainly by volatilisation/condensation. Iron and Mn were slightly enriched in slags, probably due to the high density of Fe–Mn-bearing phases. In the light of the above-mentioned properties, fly ashes and slags from the two power plants in Xinjiang will have a very high potential for a variety of uses, with very low environmental limitations. In summary, this study is demonstrating the high quality of Xinjiang coals with enormous coal reserves, and also the high quality of the combustion by-products that will be produced also in very high amounts in the near future. Major focus is on trace elements. [Copyright &y& Elsevier]

Abstract: Different monitoring parameters (PM mass concentrations, number–size distribution, black carbon, gaseous pollutants, and chemical composition, among others) are currently used in air quality studies. Urban aerosols are the result of several sources and atmospheric processes, which suggests that a single monitoring technique is insufficient to quantitatively evaluate all of them. This study assesses the suitability of a number of monitoring techniques (PM mass concentrations, number and size distribution of ultra-fine particles, levels of gaseous pollutants, and a complete chemical characterization of PM10 and PM2.5) by examining the response of those techniques to the different emission sources and/or atmospheric processes affecting an urban Mediterranean area (Barcelona, NE Spain). The results of this work reveal that the PM mass, the number concentration and the chemical composition give different, but complementary, information. Whereas the mineral matter, a key atmospheric aerosol component across the Mediterranean, is not properly quantitatively assessed by measuring sub-micrometric particles, the monitoring of the number concentration is indispensable to interpret the origin of specific aerosol episodes. Furthermore, the chemical composition yields very relevant information to deduce the causes of specific pollution episodes. The number concentration of ultra-fine particles in urban areas is strongly dependent upon vehicle exhaust emissions, which may cause adverse health impacts. Moreover, urban Mediterranean environments are favourable to produce nucleation-mode particles (<20 nm) with photochemical origin. In those cases, these particles are expected to be of high solubility and consequently their toxicity may differ from that of traffic-generated ultra-fine particles. Thus, the use of a single monitoring parameter to evaluate the health effects seems to be not enough. [ABSTRACT FROM AUTHOR]

Abstract: The properties of coal fly ash are strongly dependent on the geological origin and the combustion process of the coal. It is important to characterize regional fly ash in detail to ascertain its potential uses as raw material in the production of high value products. The physicochemical properties of fly ash coming from the “Jose Lopez Portillo” coal-fired power plant, Coahuila, Mexico (MFA), are presented in this work. A detailed study of trace elements, the chemical composition of the amorphous phase, thermal stability and the leaching of contaminant elements under different conditions are included. MFA is composed of mullite, quartz, calcite, magnetite and an amorphous phase. This material contains mainly silica (59.6%), alumina (22.8%) and magnetite (5.6%). Its amorphous phase (78.3%) has a high silica (49.4%) and alumina (14.4%) content. According to its mineralogical and chemical composition, MFA is potentially useful as a raw material for making cement, silica, and alumina, as well as low silica/alumina ratio zeolites. Deleterious elements could be removed during the zeolitization process or with an additional acid treatment. Because of its morphological properties and structural and thermal stability, MFA can be used in thermal isolation and refractory materials and as a support for heterogeneous catalysts. [Copyright &y& Elsevier]

Abstract: The geochemistry of PM10 filter samples collected at sea during the Scholar Ship Atlantic–Mediterranean 2008 research cruise reveals a constantly changing compositional mix of pollutants into the marine atmosphere. Source apportionment modelling using Positive Matrix Factorization identifies North African desert dust, sea spray, secondary inorganic aerosols, metalliferous carbon, and V–Ni-bearing combustion particles as the main PM10 factors/sources. The least contaminated samples show an upper continental crust composition (UCC)-normalised geochemistry influenced by seawater chemistry, with marked depletions in Rb, Th and the lighter lanthanoid elements, whereas the arrival of desert dust intrusions imposes a more upper crustal signature enriched in “geological” elements such as Si, Al, Ti, Rb, Li and Sc. Superimposed on these natural background aerosol loadings are anthropogenic metal aerosols (e.g. Cu, Zn, Pb, V, and Mn) which allow identification of pollution sources such as fossil fuel combustion, biomass burning, metalliferous industries, and urban–industrial ports. A particularly sensitive tracer is La/Ce, which rises in response to contamination from coastal FCC oil refineries. The Scholar Ship database allows us to recognise seaborne pollution sourced from NW Africa, the Cape Verde and Canary islands, and European cities and industrial complexes, plumes which in extreme cases can produce a downwind deterioration in marine air quality comparable to that seen in many cities, and can persist hundreds of kilometres from land. [Copyright &y& Elsevier]

Coal fly ash (FA) is abundant in countries that use steam coal for power production. The resultant FA is Class F FA (<20% CaO, Al 2 O 3 + SiO 2  > 70%, <6% Loss on Ignition) and can be used as an excellent scrubber and fixation reagent for acidic wastes containing toxic trace elements. In Spain, less than 50% of the abundant FA is currently being used. This paper reports on the potential use of Class F FA as a neutralization and fixation reagent for the hazardous sludge waste of the phosphate industry. Several analytical techniques (ICP-MS, ICP-AES, SEM-EDX, and XRD), and leaching experiments (EN12457-2) were used for this study. The results identify the best FA/waste ratios for full neutralization and fixation. Furthermore, adding a high calcium carbonate material prevents the excessive leaching of As, Mo, and Se, and facilitates full neutralization and fixation. Furthermore, the use of a safe aggregate (produced by mixing coal phosphate waste with fly ash and/or bivalve shells) as a partial substitute for sand improves the quality of concrete for civil engineering projects and is environmentally safe. [ABSTRACT FROM AUTHOR]

Currently, in Israel, phosphate acidic wastes formed during the production of phosphoric acid (H3PO4) using hydrochloric acid (HCl) are stored in large ponds. At present, this waste is only neutralized using lime (CaO) or calcite (CaCO3). This paper investigated the potential use of Class F (<20% CaO) coal fly ash (FA) as a fixation reagent of the neutralized hazardous phosphate industry waste. Studies have shown that FA can be an efficient scrubber and fixation reagent for various kinds of acidic toxic waste. Several analytical techniques including ICP-AES, ICP-MS, SEM-EDX, and XRD, ion penetration and compression/flexure strength tests (according to ASTM C1202, IS26/4.1, and 4.2 protocols), as well as leaching experiments (EN12457-2) were used to study the fixation quality and potential utilization of the fixated product as partial substitute to sand in concrete. Scrubbing phosphate waste with the FA was found to effective in reducing the leaching rate of toxic trace elements. Moreover, the use of aggregates as a partial substitute for sand in concrete improves the mechanical and chemical properties and is environmental safe. Thus, these procedures would eliminate costly treatment and storage of these toxic wastes relatively inexpensively as well as enhance industrial concrete for civil engineering projects. [ABSTRACT FROM AUTHOR]

Experimental and geochemical modelling studies were carried out to identify mineral and solid phases containing major, minor, and trace elements and the mechanism of the retention of these elements in Flue Gas Desulphurisation (FGD)-gypsum samples from a coal-fired power plant under filtered water recirculation to the scrubber and forced oxidation conditions. The role of the pH and related environmental factors on the mobility of Li, Ni, Zn, As, Se, Mo, and U from FGD-gypsums for a comprehensive assessment of element leaching behaviour were also carried out. Results show that the extraction rate of the studied elements generally increases with decreasing the pH value of the FGD-gypsum leachates. The increase of the mobility of elements such as U, Se, and As in the FGD-gypsum entails the modification of their aqueous speciation in the leachates; UO2SO4, H2Se, and HAsO2 are the aqueous complexes with the highest activities under acidic conditions. The speciation of Zn, Li, and Ni is not affected in spite of pH changes; these elements occur as free cations and associated to SO4² in the FGD-gypsum leachates. The mobility of Cu and Mo decreases by decreasing the pH of the FGD-gypsum leachates, which might be associated to the precipitation of CuSe2 and MoSe2, respectively. Time-of-Flight mass spectrometry of the solid phase combined with geochemical modelling of the aqueous phase has proved useful in understanding the mobility and geochemical behaviour of elements and their partitioning into FGD-gypsum samples. [ABSTRACT FROM AUTHOR]

Abstract: Wildfires produce a significant release of gases and particles affecting climate and air quality. In the Mediterranean region, shrublands significantly contribute to burned areas and may show specific emission profiles. Our objective was to depict and quantify the primary-derived aerosols and precursors of secondary particulate species released during shrubland experimental fires, in which fire-line intensity values were equivalent to those of moderate shrubland wildfires, by using a number of different methodologies for the characterization of organic and inorganic compounds in both gas-phase and particulate-phase. Emissions of PM mass, particle number concentrations and organic and inorganic PM x components during flaming and smouldering phases were characterized in a field shrubland fire experiment. Our results revealed a clear prevalence of K+ and SO4 2− as inorganic ions released during the flaming–smouldering processes, accounting for 68–80% of the inorganic soluble fraction. During the residual-smouldering phases, in addition to K+ and SO4 2−, Ca2+ was found in significant amounts probably due the predominance of re-suspension processes (ashes and soil dust) over other emission sources during this stage. Concerning organic markers, the chromatograms were dominated by phenols, n-alkanals and n-alkanones, as well as by alcohol biomarkers in all the PM x fractions investigated. Levoglucosan was the most abundant degradation compound with maximum emission factors between 182 and 261 mg kg−1 in PM2.5 and PM10 respectively. However, levoglucosan was also observed in significant amounts in the gas-phase. The most representative organic volatile constituents in the smoke samples were alcohols, carbonyls, acids, monocyclic and bicyclic arenes, isoprenoids and alkanes compounds. The emission factors obtained in this study may contribute to the validation and improvement of national and international emission inventories of this intricate and diffuse emission source. [Copyright &y& Elsevier]

Abstract: This work was carried out in the framework of the Cal-Mex project, which focuses on investigating the atmosphere along Mexico–California border region. Sampling was carried out at two sites located in Tijuana urban area: Parque Morelos and Metales y Derivados. PM2.5 and PM10 24 h samples were collected every three days from 17th May 2010 to 27th June 2010, and were used for gravimetric and chemical analyses (major and minor elements, inorganic ions, organic and elemental carbon) of PM. A subsequent Positive Matrix Factorization (PMF) analysis was performed. PM2.5 and PM10 average concentrations during Cal-Mex were relatively lower compared to usual annual averages. Trace elements concentrations recorded in the present study were lower than those recorded in Mexico City in 2006, with the exception of Pb at Metales y Derivados, attributed to the influence of a specific industrial source, which also includes As, Cd and Tl. Apart from this industrial source, both urban sites were found to be affected by similar sources with respect to bulk PM. Fine PM (PM2.5) was mainly apportioned by fueloil and biomass combustion and secondary aerosols, and road traffic. Coarse PM (PM2.5–10) was mainly apportioned by a mineral source (sum of road dust resuspension, construction emissions and natural soil) and fresh and aged sea salt. The road traffic was responsible for more than 60% of the fine elemental carbon and almost 40% of the fine organic matter. [Copyright &y& Elsevier]

Abstract: An atmospheric aerosol study was performed in 2008 inside an urban road tunnel, in Lisbon, Portugal. Using a high volume impactor, the aerosol was collected into four size fractions (PM0.5, PM0.5–1, PM1 – 2.5 and PM2.5 – 10) and analysed for particle mass (PM), organic and elemental carbon (OC and EC), polycyclic aromatic hydrocarbons (PAH), soluble inorganic ions and elemental composition. Three main groups of compounds were discriminated in the tunnel aerosol: carbonaceous, soil component and vehicle mechanical wear. Measurements indicate that Cu can be a good tracer for wear emissions of road traffic. Cu levels correlate strongly with Fe, Mn, Sn and Cr, showing a highly linear constant ratio in all size ranges, suggesting a unique origin through sizes. Ratios of Cu with other elements can be used to source apportion the trace elements present in urban atmospheres, mainly on what concerns coarse aerosol particles. [Copyright &y& Elsevier]

Abstract: Water re-circulation to the scrubber and co-combustion of coal with petroleum coke are the most significant factors that affect the retention capacity for trace elements in a power plant equipped with a forced-oxidation flue gas desulphurisation (FGD) system. The water re-circulation favours the progressive saturation of most elements in the gypsum slurry with the subsequent increase in emission by entraining particles and droplets in the outgoing gas of FGD (OUT-FGD). The co-combustion increases the content of HCl and SO2 in the gaseous stream, which enhances the formation of gaseous chlorides species, especially of Hg, and the formation of condensed species of Cu, Cr, Ni, Na, Cd, and Zn OUT-FGD, respectively. High gaseous retention capacity (83–100%) for S, Cl, F, As, and B is attained by the whole plant with a subsequent reduction in their gaseous emissions below the limits established by the European directive 2001/80/EC for large combustion plants, and also below the Pollutant Release and Transfer Register (PRTR) threshold values. The retention of Se increases from 2007 (75%) to 2008 (97%). The emissions of gaseous Hg and particulate As, Zn, and Ni exceed the PRTR values. Remediation actions for the gaseous and PM emissions are relevant given the role of the filtered water re-circulation increasing the particles emissions OUT-FGD. [Copyright &y& Elsevier]

Abstract: The extraction of sulphur produces a hematite-rich waste, known as roasted pyrite ash, which contains significant amounts of environmentally sensitive elements in variable concentrations and modes of occurrence. Whilst the mineralogy of roasted pyrite ash associated with iron or copper mining has been studied, as this is the main source of sulphur worldwide, the mineralogy, and more importantly, the characterization of submicron, ultrafine and nanoparticles, in coal-derived roasted pyrite ash remain to be resolved. In this work we provide essential data on the chemical composition and nanomineralogical assemblage of roasted pyrite ash. XRD, HR-TEM and FE-SEM were used to identify a large variety of minerals of anthropogenic origin. These phases result from highly complex chemical reactions occurring during the processing of coal pyrite of southern Brazil for sulphur extraction and further manufacture of sulphuric acid. Iron-rich submicron, ultrafine and nanoparticles within the ash may contain high proportions of toxic elements such as As, Se, U, among others. A number of elements, such as As, Cr, Cu, Co, La, Mn, Ni, Pb, Sb, Se, Sr, Ti, Zn, and Zr, were found to be present in individual nanoparticles and submicron, ultrafine and nanominerals (e.g. oxides, sulphates, clays) in concentrations of up to 5%. The study of nanominerals in roasted pyrite ash from coal rejects is important to develop an understanding on the nature of this by-product, and to assess the interaction between emitted nanominerals, ultra-fine particles, and atmospheric gases, rain or body fluids, and thus to evaluate the environmental and health impacts of pyrite ash materials. [Copyright &y& Elsevier]

Abstract: Petrographic, mineralogical and geochemical studies have been carried out on beneficiated coal products from mines and preparation plants in the Santa Catarina Basin, southern Brazil, to investigate the range of characteristics exhibited by the materials and the potential impact of their stockpiling and storage on the environment. The coals contain varying proportions of vitrinite and inertinite macerals, and have vitrinite reflectance values ranging from 0.44 to 1.38%. With the exception of one material blended with peat from an external source, they have relatively high percentages of ash (30–58%) and mineral matter (36–66%). The mineral matter consists mainly of clay minerals (kaolinite, illite and illite/smectite), together with 15–25% quartz, up to 10% feldspar, up to 5% calcite and/or dolomite and up to 5% pyrite, and around 1% anatase and/or rutile. Bassanite is also present in low-temperature ash derived from the coals, mainly derived from interaction of Ca and S associated with the organic matter. Jarosite is formed by pyrite oxidation in coals that have been exposed in stockpiles for extended periods. Most of the trace elements in most of the coals have higher concentrations than average values for world coals generally, probably due to the relatively high mineral matter content. A lower-ash product representing a blend of coal and peat has similar to lower concentrations of most elements, but higher concentrations of B, Ba, Be, Cd, Ge and Mn, which may be associated with the peat component. Interaction of relatively fresh coals with water in laboratory tests produces leachates with near-neutral to mildly acid pH values, but leaching of oxidized, jarosite-bearing coal produces a strongly acid leachate, with higher concentrations of Cd, Co, Cu, Ni and Zn. Leachates derived from coals in which the pyrite has been oxidized during storage would thus be expected to have a more adverse environmental impact than leachates derived from coals in which such oxidation has not had an opportunity to develop. [Copyright &y& Elsevier]

Abstract: The mineralogical and geochemical characteristics of the Late Permian Huayingshan coals, partings, roof and floor strata, as well as lutitic rocks from the Longtan Formation, in Sichuan Province, southwestern China, were investigated in this study. The Huayingshan low volatile bituminous coals are characterized by relatively high mineral contents (mainly kaolinite, quartz, pyrite, and calcite). The concentrations of most trace elements are relatively high compared with other Chinese and world coals. The coals and associated strata show similar element affinities: Al, Ti, Li, Ta, Th, Ga, U, Sn, Sc, Cr, Cu, Rb, Co, and Se probably have an aluminosilicate affinity; Zr, Nb, Hf, Y, REEs, and U probably result from the occurrence of heavy minerals such as zircon; S, Fe, W, and Rb mainly have a sulfide affinity; Ca, Sr, and Mn mainly have an carbonate affinity. The high enrichment in the Huayingshan coal of Zr, Nb, Hf, REEs, Ta, Ga, and Th is caused by a geochemical anomaly in the source of this coal''s detrital material (and probably also by input of volcanic ash), which is influenced by the alkaline volcanic magmas of the Emeishan basalt. The Zr/Hf, Zr/Nb, Zr/La and Zr/Th ratios support the volcanic origin of such a geochemical anomaly. [Copyright &y& Elsevier]

Abstract: The Zhundong coalfield is a very large coal deposit, currently under exploration, and promises to be an important coal mining resource in Western China. The coal reserves amount to 164Gt. At Xiheishan and Wucaiwan, the coal-bearing units are the Badaowan (Lower Jurassic) and, especially, the Xishanyao formations (Middle Jurassic). These contain from one to 31 coal seams (one to 10 workable coals reaching the rank of high volatile A bituminous) with an accumulated workable coal thickness of 20–87m. These recently explored coal reserves are of a high quality and are characterized by low ash, aluminum, iron, sulfur, and trace element contents. The minerals present in this coal are mainly quartz, kaolinite, siderite, and pyrite. The trace element contents in both Xiheishan and Wucaiwan coals are much lower when compared with the usual concentration ranges present in Chinese coals, with the exception of Ba and Sr. Thus, Ba contents in Xiheishan coal are higher than Swaine''s worldwide concentration range. A large number of elements have mainly aluminosilicate affinity, and occur in clay and other detrital coal minerals. Ca and Mn have mainly carbonate affinity; Fe and S have mainly sulphide affinity in Wuchaiwan coal. In Xiheishan, Fe, Mn and Mg have mainly carbonate affinity (siderite), and probably, B, Co, Ni and S have an organic affinity. Thus, the Zhundong coalfield contains coal with a very high quality and very low levels of impurities. The very low ash yields, S, Fe, and trace element contents may be attributed to the sedimentological setting, with intensive peat bog aggradation in a very shallow lake environment with a low detrital supply. The very low sulfur content, the relatively high Ba-sulfate (barite) content and the high siderite occurrence in Xiheishan coal (in contrast to the pyrite occurrence in Wucaiwan coal) may be attributed to the rapid aggradation of peat with the consequent oxidation and leaching of minerals, elements, and degradation of organic components. Under this scenario, sulfate is trapped by the continuous precipitation and accumulation of barium sulfate (very low soluble). [Copyright &y& Elsevier]

Abstract: The phase-mineral and chemical composition of six fractions recovered from two fly ashes (FAs) produced in the Soma power station (Turkey) was characterized to predict their possible environmental concerns and potential utilization directions. A combination of conventional separation procedures including sieving, hand picking, sink–float and magnetic separations, as well as leaching and evaporation, was used to isolate the following fractions: (1) char concentrates (CCs); (2) light fractions (<1 g cm−3) (LFs); (3) water-soluble residues (WRs); (4) magnetic fractions (MFs); (5) nonmagnetic coarse-grained fractions (>63 μm) (NCFs); and (6) nonmagnetic fine-grained fractions (<63 μm) (NFFs). CCs (3.3–3.4%) are composed of char (61–68%) and some inorganic phases, and are highly enriched in U>S>Mn>Mo>Fe>Sb. LFs (0.4–0.8%) contain porous cenosphere, spongy, and vesicular char types (21–54%) impregnated by calcite, anhydrite, portlandite, and clay minerals. These fractions show high concentrations of Sb>Se>As. WRs (1.7–2.6%) consist of gypsum, portlandite, Ca oxalate, and calcite (92–98%), and are highly enriched in water-soluble Sb>Mo>S>Ca. The greatest amounts (1–37%) leached from FAs reveal Sb>Mo>S>Ca>Sr>Se>(B, Na)>Li. MFs (1.4–2.3%) are concentrated in magnetite, hematite, and Fe-spinel (31–39%), and are highly enriched in Mn>Fe>Co>Cu>Ni>Zn>(Mo, Yb)>(Lu, Tm, Y)>(Er, Ho, Mg)>Sb. NCFs (49–56%) include mostly coarse-grained glass, quartz, calcite, and mullite, and these are the poorest in trace elements fractions. NFFs (39–47%) contain dominantly fine-grained glass, calcite, quartz, char, and mullite, and are slightly enriched in some chalcophile elements. Possible environmental concerns are related mainly to the trace element mobility in WRs, LFs, and CCs, while the potential utilization directions are connected mostly with the composition of MFs, WRs, CCs, LFs, and NFFs. [Copyright &y& Elsevier]

Abstract: The phase–mineral and chemical composition of feed coals (FCs) and their bottom ashes (BAs) and fly ashes (FAs) produced in the Soma thermo-electric power station (TPS), Turkey, was characterized. FCs are high-ash Soma subbituminous coals abundant in moisture and Ca, and depleted in S. The inorganic composition (in decreasing order of significance) of FCs includes calcite, quartz, kaolinite, illite+muscovite, chlorite, plagioclase, gypsum, pyrite, montmorillonite, K-feldspar, dolomite, siderite, ankerite, opal, and volcanic glass. The results for 57 elements studied show that Ca>Nb>Cs>(V, Li) have significantly higher contents in FC ashes than the respective Clarke values for coal ashes. The water-soluble residues isolated from FCs include gypsum, calcite, inorganic amorphous matter, Ca–Mg–Na–K phase, and opal. These residues are enriched in Na>Se>S>B>Mg>Mo>Sr>Ca>K. The phase–mineral composition of BAs and FAs includes mainly glass, quartz, char, mullite, plagioclase, calcite, and portlandite; and, to a lesser extent, illite+muscovite, melilite, hematite, anhydrite, lime, cristobalite, kaolinite, and magnetite. Minor amounts of K-feldspar, dolomite, ankerite, Fe-spinel, gypsum, and Ca–K–Na phase also occur in BAs and FAs. FAs are enriched in inorganic matter, glass, cristobalite, mullite, Fe oxides, lime, and anhydrite, and depleted in mineral matter, char, quartz, clay minerals, melilite, portlandite, and carbonates in comparison with BAs. Only Se is significantly enriched in BAs and FAs compared to FC ashes. Most of the trace elements (in particular As, Bi, Cd, Ge, Pb, Sn, Tl, and W) are more abundant in FAs, while BAs are more enriched in Ca, Cs, Fe, Ho, Mn, P, Sc, Se and Tb. Significant percentages (11–59%) of elements initially present in FCs, namely S>Sb>Sn>Ta>Mo>Bi>Zn>Ni>Na>(Lu, Tm)>B, were emitted by stack emissions and not captured by the cleaning equipment in the Soma TPS. Some genetic features, properties, possible environmental concerns, and potential utilization directions related to FCs, BAs, and FAs are also discussed. [Copyright &y& Elsevier]

A source apportionment study was performed to characterise PM10 sources in the urban area of Madrid. Receptor modelling techniques were applied to obtain the different source contributions, identifying four main sources that contribute to most of the analysed PM10 mass, namely: road traffic, crustal/mineral, secondary and marine aerosol. PM10 mean concentration and chemical profile were obtained for each source category by multilinear regression analysis. Road traffic was found to be the major contributor to the PM10 mass (48%), together with crustal (26%) and secondary particles (18%). A minor contribution has been associated to marine aerosol (3%), while 5% of the PM10 mass has been attributed to non-identified sources. An analysis of the geographical origin was performed for remote sources. Residence time probability values were calculated based on air mass back trajectories information. Different elements have been selected as tracers of the sources. Desertic regions from North Africa have been identified as the most significant source area for crustal particles, with a high content of Al and Ti. Atlantic ocean regions have been identified as weak to intermediate source areas of Na, supporting the marine source identified by the factor analysis. Then the influence of remote natural sources on the PM10 levels in central Spain has been detected by the use of single components as tracers, even at urban sites highly affected by traffic. [Copyright &y& Elsevier]

• Inorganic trace pollutants are studied in a coal-fired power station in China. • The aqueous (NH 4) 2 SO 4 slurry (pH 3.2) is enriched in inorganic trace pollutants. • NH 3 -FGD performance for the retention efficiency of trace pollutants is questioned. • Acidic conditions of the aqueous (NH 4) 2 SO 4 slurry could lead to low FGD efficiencies. • Operating conditions may affect Hg fate across the PCC-SCR-ESP-NH 3 -FGD. The behaviour and speciation of inorganic trace pollutants were studied in a 270 MWh coal-fired power station equipped with denitrification (DeNOx)-based selective catalytic reduction (SCR), electrostatic precipitators (ESP) and ammonia flue gas desulphurisation (NH 3 -FGD) controls. The aqueous (NH 4) 2 SO 4 slurry (pH 3.2) showed remarkably high concentrations of SO 4 2−, Cl−, Fe, NH 4 +, PO 4 3−, and F− and was substantially enriched in multiple trace pollutants, e.g. Mn, Ni, Zn, and As, which can be ascribed to the diffusion of gaseous pollutants released during combustion and to the partial dissolution of fly ash (FA) particles entrained in the flue gas FGD. These processes were favoured by the iteration of the FGD water re-circulation cycles within the scrubber. Three major unresolved performance issues remain for the NH 3 -FGD with respect to the retention efficiency of major and trace pollutants: (i) the high concentration of soluble salts and major and minor trace elements in the aqueous (NH 4) 2 SO 4 slurry could lead to entrainment of droplets and particles with the outgoing (OUT)-FGD gas; (ii) the ionic strength, as a result of the high concentration of the elements associated with soluble salts and major and minor elements, could lead to diminishing diffusivity of gaseous pollutants into the aqueous phase, where these are supposed to dissolve; and (iii) the acidic conditions of the aqueous (NH 4) 2 SO 4 slurry, caused by Fe-hydrolysis, could lead to low FGD efficiencies. Operating conditions at this power station affect Hg partitioning and fate across the PCC-SCR-ESP-NH 3- FGD. [ABSTRACT FROM AUTHOR]

Based at Izaña Observatory (~2400 m a.s.l. in Tenerife), we performed 1-h resolution measurements of elemental composition of dust in the Saharan Air Layer (SAL) and studied the variability of the ratios of these elements to aluminium (elemental ratios). In a period (~1 week) of continuous dust presence (50–200 μg/m3), we observed rapid variations of dust composition; some elemental ratios changed by a factor 2 in a few (5–8) hours. The lowest variability (Normalized Variability Range, %) was found for Si/Al (9%) and Fe/Al (9%), followed by the ratios of K, Ti, Mg, Mn, Ca and Sr to Al (20–80%), and the highest for S/Al, Na/Al and Cl/Al (110–160%) and a number of trace metals (Cr, Cu, Ni, Zn, Zr) and Br (>200%). This variability was induced by the alternating impacts of three of the large North African dust sources: NE Algeria (rich in evaporite minerals bearing Ca, S, Sr, K and Mg and in illite mineral), Western Sahara to Bechar region (containing Na, S and Cl rich Yermosol soils) and SW Sahara – Western Sahel (rich in illite and hematite). We traced the variability in large-scale meteorology using the so-called North African Dipole Intensity (NAFDI: strength of the subtropical Saharan high -Morocco-to the monsoon tropical low -Nigeria-). The mobilization of dust from the different sources was associated with westward propagating Harmattan pulses linked to the change of phase of NAFDI (- to +), the associated westward shifts of the Saharan Heat Low and convective monsoon inflow. We found a correlation between dust composition in the SAL and NAFDI: moderate NAFDI values (0 to +2.5) were associated with Ca, K, Na, Mg and S rich dust linked to dust sources in NE Algeria, whereas higher NAFDI values (+2.5 to +4) were linked to Fe rich dust (Ca, Na and S depleted) linked to dust sources in SW Sahara – Western Sahel. The results of this study also show that some trace elements (Br, Cr, Ni, Zn and Zr) are influenced by industrial emissions into North Africa. Image 1 • Dust composition changes rapidly, ~5–8 h, in the Saharan Air Layer. • North African Dipole Intensity NAFDI traces the variability of summer meteorology. • Positive phase of NAFDI enhances dust export to the North Atlantic. • Negative phase of NAFDI enhances dust export to the Western Mediterranean. • NAFDI connects meteorology, sources and dust composition in the Saharan Air Layer. [ABSTRACT FROM AUTHOR]