Quantitative arsenic speciation in two species of earthworms from a former mine site

The relationship between the total arsenic concentration and the chemical speciation of arsenic in two species of earthworm (Lumbricus rubellus and Dendrodrilus rubidus) in relation to the host soil, was investigated for 13 sites of varying arsenic content, including a background level garden soil and a former mine site at the Devon Great Consols, UK. Earthworms were collected with the host soil (As soil concentration range 16-12, 466 mg kg(-1) dry weight) and measured for their total arsenic (concentration range 7-595 mg kg(-1) dry weight) using inductively coupled plasma mass spectrometry (ICP-MS). A methanol-water mixture was used to extract arsenic species from the earthworms prior to determination of the individual arsenic species by a combination of anion and cation exchange high performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (HPLC-ICP-MS). A gradient elution anion exchange method is presented whereby nine arsenic species could be measured in one sample injection. Arsenic species were identified by comparison of retention times and sample spiking with known standards and a fully characterised seaweed extract. Arsenic was generally present in the earthworm as arsenate (As(V)) or arsenite (As(III)) and arsenobetaine (AB). Methylarsonate (MA), dimethylarsinate (DMA) and three arsenosugars (glycerol, phosphate, sulfate) were present as minor constituents. These results are discussed in relation to the mechanisms for coping with exposure to soil bound arsenic.     

Arsenic compounds in the haemolymph of the Dungeness crab, Cancer magister, as determined by using HPLC on-line with inductively coupled plasma mass spectrometry

Arsenobetaine, two arsenosugars, dimethylarsinate and several unidentified arsenic species were detected in extracts of the haemolymph of the Dungeness crab, Cancer magister, by using HPLC-ICP-MS. This is the first report of the presence of arsenosugars in the haemolymph/blood of marine animals. Total, extractable and residual arsenic concentrations were determined by ICP-MS. The concentration of total arsenic was in the range of 1.4-3.8 [micro sign]g ml(-1). Nearly all (98%) the arsenic was found to be extractable, and accounted for primarily by arsenobetaine, two arsenosugars and dimethylarsinate. The results demonstrate that arsenic compounds present in the diet of crabs are not fully metabolized in the gut. They are, at least partly, taken up into the haemolymph. The concurrence of arsenobetaine and arsenosugars suggests that the use of repeated haemolymph sampling in crustaceans could facilitate investigations into the kinetics of the biotransformation pathways of arsenic compounds. Finally, the present study clearly demonstrates the unique capabilities of HPLC-ICP-MS for the detection and identification of minor arsenic components amongst the predominant arsenobetaine.     

Speciation of arsenic using solid phase extraction cartridges

Various solid phase extraction (SPE) cartridges were investigated for speciation of arsenite [As(III)], arsenate [As(v)], monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA). Cartridges containing different types of sorbent materials were tested for arsenic retention and elution characteristics. Alumina cartridges were found to completely retain all the four target arsenic species, and are suitable for removal and preconcentration purposes. For speciation analysis, different arsenic species were separated on the basis of their selective retention on and elution from specific cartridges. DMA was retained on a resin-based strong cation exchange cartridge and eluted with 1.0 M HCl. MMA and As(v) were both retained on a silica-based strong anion exchange cartridge and sequentially eluted with 60 mM acetic acid (for MMA) and 1.0 M HCl [for As(v)]. As(III) was not retained on either cartridge and remained in solution. Arsenic species in solution and those eluted from the cartridges were subsequently quantified by using flow injection with hydride generation atomic fluorescence spectrometry (FI-HGAFS) and hydride generation atomic absorption spectrometry (FI-HGAAS). A detection limit of 0.05 microg L(-1) arsenic in water sample was achieved using HGAFS. An application of the method was demonstrated at a drinking water treatment facility. As(III) and As(v) species were determined in water at various stages of treatment. The method is suitable for routine determination of trace levels of arsenic in drinking water to comply with more stringent environmental regulations.     

Arsenic contamination and speciation in surrounding waters of three old cinnabar mines

The impact of arsenic pollution in waters from the surroundings of three abandoned Hg mines in Northern Spain, as well as reaching the Caudal River, was evaluated. For assessing the factors controlling arsenic release, an extensive study based on the physicochemical characterization and multivariate statistical analysis of waters upstream and downstream each mine site was performed. Waters downstream of the La Soterra?a mine present the highest arsenic concentrations, up to 38.8 mg L(-1), coming mainly from the solubilisation of calcium, magnesium and strontium arsenates at a pH close to neutral. Although arsenic concentrations downstream of La Pe?a are markedly lower, these values remain too high, indicating that the encapsulation carried out in this spoil heap is insufficient. In addition, the high water flow in this point involves an extremely high input of arsenic to the surroundings (0.3 g s(-1)). Waters close to tailings from Los Rueldos suffer from acid mine drainage, provoking an important solubilisation of arsenic and heavy metals, a situation which is rapidly softened with distance. The study of arsenic speciation reveals the omnipresence of As(v) in waters from the three mines, whereas in La Pe?a low amounts of As(iii) were also detected. Different preservation methods for As speciation were compared, such as the addition of HCl, EDTA and the storage of samples without any additive, and no alteration of samples in any case up to nine months after the collection was observed. A study of seasonal variations of As and the main parameters affecting its concentration and speciation was completed throughout a year, showing no remarkable dependency with rainfall for any studied variable.     

Arsenic Speciation Analysis in Water Samples: A Review of The Hyphenated Techniques

Interests in the determination of different arsenic species in natural waters is caused by the fact that toxic effects of arsenic are connected with its chemical forms and oxidation states. In determinations of water samples inorganic arsenate (As(III), As(V)), methylated metabolities (MMAA, DMAA) and other organic forms such as AsB, AsC, arsenosugars or arsenic containing lipids have the most importance. This article provides information about occurrence of the dominant arsenic forms in various water environments. The main factors controlling arsenic speciation in water are described. The quantification of species is difficult because the concentrations of different forms in water samples are relatively lowcompared to the detection limits of the available analytical techniques. Several hyphenated methods used in arsenic speciation analysis are described. Specific advantages and disadvantages of methods can define their application for a particular sample analysis. Insufficient selectivity and sensitivity of arsenic speciation methods cause searching for a new or modifications already existing techniques. Some aspects of improvement and modifications of the methods are highlighted.     

Occurrence and sorption properties of arsenicals in marine sediments

The content of total arsenic, the inorganic forms: arsenite (As(III)) and arsenate (As(V)), the methylated forms: monomethylarsonic acid and dimethylarsinic acid (DMA), trimethylarsenic oxide, tetramethylarsenonium ion and arsenobetaine was measured in 95 sediment samples and 11 pore water samples from the Baltic Sea near the island of Bornholm at depths of up to 100 m. As(III+V) and DMA were detected in the sediment and As(III+V) was detected in the sediment pore water. Average total As concentration of 10.6?±?7.4 mg/kg dry matter (DM) in the sediment corresponds to previously reported values in the Baltic Sea and other parts of the world. Existing data for on-site measurements of sorption coefficients (Kd) of arsenicals in marine and freshwater sediments show large variability from <1 to >1,000 L/kg. In this work, calculated sorption coefficients (Kd and Koc) for As(III+V) showed significant correlation with depth, dissolved oxygen (DO), salinity and sediment classification; for depths <70 m, salinity <11 %, DO >9 mg/L and sand/silt/clay sediments the Kd was 118?±?76 L/kg DM and for depths >70 m, salinity >11 %, DO?<?9 mg/L and muddy sediments the Kd was 513?±?233 L/kg DM. The authors recommend using the found Kd value for arsenic in marine sediments when conditions are similar to the Baltic Sea. At locations with significant anthropogenic point sources or where the local geology contains volcanic rock and sulphide mineral deposits, there may be significantly elevated arsenic concentrations, and it is recommended to determine on-site Kd values.     

Effect of fasting on the pattern of urinary arsenic excretion

Millions of people in some of the poorest regions of the world are exposed to high levels of arsenic through drinking contaminated water. It has been reported that development of cancer caused by arsenic exposure in such populations is dependent on dietary and nutritional factors which can modulate arsenic metabolism. Many people in arsenic exposed regions of Bangladesh and India practice fasting for at least one month every year when they refrain from consumption of food and fluid during daylight hours. How such practices may modulate arsenic metabolism has not been previously investigated. This study investigated this issue by determining total arsenic and its species in urine samples from a group of 29 unexposed volunteers at the beginning of the fasting and at the end of approximately 12 h of fasting period. Inductively coupled plasma mass spectrometry (ICP-MS) and high performance liquid chromatography (HPLC) coupled with ICP-MS was used to measure the total arsenic and arsenic speciation in the urine samples, respectively. The mean total levels of arsenic at the beginning of fasting (18.3 microg g(-1) creatinine) and at the end of approximately 12 h of fasting (17.7 microg g(-1) creatinine) did not differ significantly (p > 0.05). However, the percentages of urinary arsenic as the methylated arsenic species methylarsonate (MA) were found to be significantly different (p < 0.05) and this species was observed more frequently at the end of fasting, although its overall concentration was similar. There were no significant differences (p > 0.05) in both the concentrations and percentages of other urinary arsenic species detected, namely arsenobetaine (AB) and dimethylarsinate (DMA). Arsenite (As(III)) and arsenate (As(V)) were also analyzed, but were not detected. We conclude that fasting for a period of 12 h results in a significant increase in the percentage of urinary arsenic as MA, and its frequency of detection in the volunteers at the end of the fasting period is almost nine fold higher. This suggests that metabolism of arsenic is altered by fasting.     

Speciation of arsenic in plants by HPLC-HG-AFS: extraction optimisation on CRM materials and application to cultivated samples

A recently developed method for the determination of arsenic species (arsenite, arsenate, monomethylarsonate, MMAA, and dimethylarsinate, DMAA) has been applied to the study of arsenic speciation in plants. This method uses ion-exchange liquid chromatography coupled on-line to atomic fluorescence spectrometry through continuous hydride generation. Various extraction procedures have been studied in detail using three plant certified reference materials. None of the procedures tested revealed fully satisfying results with all kinds of plant samples; microwave assisted extraction with 0.3 mol dm-3 orthophosphoric acid was found to be the most convenient for dealing with terrestrial plants. Species stability appears good. This method was applied to real world cultivated plant parts. Arsenate appears to predominate in soils, roots and leaves; unidentified species (probably arsenosugars) play an important role (60%) in rice fruits. Carrot was found to be the most contaminated edible plant part, containing 1 mg kg-1 essentially as arsenate species. MMAA was detected in all soils and some plant parts especially shallots at low levels, whereas DMAA was found only in one soil sample and in hot pepper leaves. Arsenite is a minor component of all soils; it is also present in some plant parts at low levels. However, no evident relationships were found between As speciation in the various plant parts and much more detailed studies will be necessary to elucidate As behaviour in plants.     

Arsenic speciation in human hair: a new perspective for epidemiological assessment in chronic arsenicism

The analysis for arsenic in hair is commonly used in epidemiological studies to assess exposure to this toxic element. However, poor correlation between total arsenic concentration in hair and water sources have been found in previous studies. Exclusive determination of endogenous arsenic in the hair, excluding external contamination has become an analytical challenge. Arsenic speciation in hair appears as a new possibility for analytical assessing in As-exposure studies. This study applied a relative simple method for arsenic speciation in human hair based on water extraction and HPLC-HG-ICP-MS. The concentration of arsenic species in human hair was assessed in chronically As(V)-exposed populations from two villages (Esqui?a and Illapata) of the Atacama Desert, Chile. The arsenic concentrations in drinking water are 0.075 and 1.25 mg L(-1), respectively, where As(V) represented between 92 and 99.5% of the total arsenic of the consumed waters. On average, the total arsenic concentrations in hair from individuals of Esqui?a and Illapata were 0.7 and 6.1 microg g(-1), respectively. Four arsenic species, As(III), DMA(V), MMA(V) and As(V), were detected and quantified in the hair extracts. Assuming the found species in extracts represent the species in hair, more than 98% of the total arsenic in hair corresponded to inorganic As. On average, As(III) concentrations in hair were 0.25 and 3.75 microg g(-1) in Esqui?a and Illapata, respectively; while, the As(V) average concentrations were 0.15 and 0.45 microg g(-1) in Esqui?a and Illapata, respectively. Methylated species represent less than 2% of the extracted As (DMA(V)+ MMA(V)) in both populations. As(III) in hair shows the best correlation with chronic exposure to As(V) in comparison to other species and total arsenic. In fact, concentrations of As(total), As(III) and As(V) in hair samples are correlated with the age of the exposed individuals from Illapata (R= 0.65, 0.69, 0.57, respectively) and with the time of residence in this village (R= 0.54, 0.71 and 0.58, respectively).     

Arsenic speciation in freshwater snails and its life cycle variation

Terrestrial snails are consumed by humans occasionally and they are an important food source for many creatures including fish and birds. Little is known about arsenic speciation in these gastropods, let alone life cycle variations. Here we report on the arsenic speciation in freshwater snails from Pender Island and Vancouver Island, B.C., Canada, which was determined on methanol/water extracts (43-59% extraction efficiency) by using high performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS) and HPLC-electrospray tandem mass spectrometry. The tetramethylarsonium ion, oxo-arsenosugars and thio-arsenosugars are the main arsenic species encountered. Arsenobetaine, which is commonly found in the marine environment, is minor. Live bearing snails Viviparidae sp. from Pender Island were maintained in aquaria and the arsenic speciation in the unborn, newly born, and adult animals was monitored. Oxo-arsenosugars predominate in the adults, whereas thio-arsenosugars seem to predominate in juveniles, suggesting that these arsenicals are snail metabolites.     

Investigation of arsenic speciation on drinking water treatment media utilizing automated sequential continuous flow extraction with IC-ICP-MS detection

Three treatment media, used for the removal of arsenic from drinking water, were sequentially extracted using 10 mM MgCl2(pH 8), 10 mM NaH2PO4(pH 7) followed by 10 mM (NH4)2C2O4(pH 3). The media were extracted using an on-line automated continuous extraction system which allowed the arsenic in each of the extraction fluids to be speciated on-line using IC-ICP-MS. The 10 mM MgCl2 preferentially extracted As(III) from each of the media. The percentage of the arsenic extracted by the MgCl2, relative to a HNO3/H2O2 digestion of the media, ranged from 0.1-2.3% for the three solids. The next sequential extraction fluid, 10 mM NaH2PO4, extracted some of the residual As(III) remaining on each of the media but the predominant species extracted was As(V). The 10 mM NaH2PO4 extracted 15.3 to 42.8% of the total arsenic relative to a total digested concentration for each of the media. The As(III) and As(V) stability studies conducted in these two extraction fluids indicated that conversion between As(III) and As(V) was not significant for the short extraction fluid sample contact time associated with the on-line continuous flow extraction cell. Finally, the 10 mM (NH4)2C2O4 extraction fluid was utilized in an off-line analysis mode because the Fe and As concentrations extracted from the media were not compatible with direct ICP-MS detection. The (NH4)2C2O4 extracted 2.9-29% As(III) for all three media and caused an oxidation of As(III) to As(V) during the extraction period for one of the three media. The sum of the arsenic from each of the three extraction fluids represented 92%, 44% and 53% of the available total arsenic for the three media, respectively. The speciation results for each media were obtained by adding all the speciation results from all three extraction fluids together and the resulting distribution of As(III)/As(V) compared well with the speciation results obtained via XANES.     

Arsenic concentration and speciation in five freshwater fish species from Back Bay near Yellowknife, NT, CANADA

The concentration of total arsenic and five different arsenic species [As(III), As(V), monomethylarsonic acid (MMA), dimethylarsenic acid (DMA), and arsenobetaine (AsB)], were measured in the muscle, liver and gastrointestinal tract (GIT) of five different fish species [lake whitefish (Coregonus clupeaformis), walleye (Stizostedion vitreum), northern pike (Esox lucius), white sucker (Catostomus commersoni) and longnose sucker (Catostomus catostomus)] from Back Bay, Great Slave Lake, near the city of Yellowknife, NT, Canada. The total concentration (dry weight) of arsenic in muscle ranged from 0.57 to 1.15 mg/kg, in the liver from 0.42 to 2.52 mg/kg and in the GIT from 1.48 to 8.92 mg/kg. Among fish species, C. commersoni had significantly higher total arsenic concentrations in the GIT than S. vitreum, E. lucius and C. clupeaformis, and higher total arsenic concentrations in the liver than C. clupeaformis. The mean concentration of As(III) and As(V) in the muscle of all fish ranged from < or =0.01 to 0.05 mg/kg and < or =0.01 to 0.02 mg/kg, respectively, and together comprised < or =7.5% of the total arsenic measured in muscle. The concentrations of MMA were below detection in the muscle of all five fish species. However, AsB and DMA were measured in all fish species and nearly all fish tissues. The concentrations of AsB ranged from 0.01 to 0.13 mg/kg and the concentrations of DMA ranged from <0.02 to 0.45 mg/kg. The majority (>50%) of organic arsenic in almost all of the tissues from fish caught in Back Bay was not directly identified. Evidence from the literature suggests that most of these other organic arsenic species were likely trimethylated arsenic compounds, however, further analytical work would need to be performed to verify this hypothesis.     

Biomonitoring of arsenic through mangrove oyster (Crassostrea corteziensis Hertlein, 1951) from coastal lagoons (SE Gulf of California): occurrence of arsenobetaine and other arseno-compounds

In this study, we examined the bioavailability of arsenic through the mangrove oyster Crassostrea corteziensis sampled from seven coastal lagoons in SE Gulf of California during the rainy and dry seasons. As concentrations in soft tissue of oysters C. corteziensis fluctuated between 5.2 and 11.6 μg/g on dry weight; organisms from the control site presented the lowest As concentrations in the two sampling seasons. As speciation was evaluated in selected samples and indicated that arsenobetaine was the major arseno-compound accounting for 53.5–74.7 % of total As. Lower percentage contributions were obtained for nonextractable As (9.7–25.5 %) and other molecules such as arsenocholine and methyl-arsonate (<5 %). Inorganic As was detectable in only two samples, at concentrations lower than 0.1 μg/g. These As data are the first generated in NW Mexico and indicate that C. corteziensis is safe for human consumption in terms of arseno-compounds. It is evident that As bioavailability in these lagoons is low.     

Speciation of inorganic arsenic in coastal seawater from Ionian and Tyrrhenian Seas (Sicily, Italy) using derivative anodic stripping chronopotentiometry

The purpose of this paper was to use derivative anodic stripping chronopotentiometry (dASCP) as a sensitive and accurate technique, to determine the concentrations of dissolved As (III) and As (V) in coastal seawater samples from the Straits of Messina, the Ionian and the Tyrrhenian seas, and to investigate the relationship between the anthropogenic activities on the coastal areas and the concentration of dissolved inorganic arsenic in seawaters. The obtained data indicated that As (V) was the most abundant species, with concentration ranging from 26.7 to 307 nM, whereas As (III) levels were lower than 48 nM in all the samples. In particular, As (III) and As (V) levels significantly decreased from high to low anthropogenic activities zones (p < 0.00001, ANOVA), with the reference samples, from a wildlife reserve, showing the lowest values. Furthermore it was observed that human activities influenced inorganic arsenic speciation, since the zones that received high human input presented the highest As(V)/As (III) ratio.     

Modeling Phosphate Influence on Arsenate Reduction Kinetics by a Freshwater Cyanobacterium

Arsenic speciation in natural surface-water systems can be highly impacted through biological processes that result in non-thermodynamically predicted species to dominate the system. In laboratory experiments, arsenate reduction by a freshwater cyanobacterium exhibited saturation kinetics increasingly inhibited by elevating solution phosphate concentrations. Approximately 100% arsenate reduction occurred by days 4, 7, and 10 in the low (0.35 μm), middle (3.5 μm), and high (35 μm) phosphate treatments, respectively, with maximum arsenate reduction rates ranged from 0.013 μmol As g C⁻¹ day⁻¹ in the high-phosphate treatment to 0.398 μmol As g C⁻¹ day⁻¹ in the low-phosphate treatment. Saturation kinetic models were utilized to evaluate the impact of cell growth and arsenate-phosphate uptake competition on arsenate reduction rates by the cyanobacterium. Results showed reduced arsenicals dominate arsenic speciation once growth reached steady state, indicating reduced arsenicals may dominate natural systems, even when considering conservatively high, abiotic arsenic reoxidation.     

Arsenic concentration and speciation of the marine hyperaccumulator whelk Buccinum undatum collected in coastal waters of Northern Britain

European whelks (Buccinum undatum) have shown to accumulate high levels of arsenic. Since the accumulation process is not well understood it is necessary to gain information about the geographical variability of the arsenic concentration in them. Here we show that the mean arsenic concentrations of the whelks are site specific and vary by a factor of 3.5 in ten different geographical locations. At fishing grounds where whelks exhibited low arsenic concentrations the arsenic concentration increased linearly with size, whereas the whelks with high arsenic levels from a different location showed no correlation. Although the overall arsenic concentration in the whelks differed between 45 and 655 mg kg(-1) d.w., the inorganic arsenic concentration did not exceed 0.4 mg kg(-1) d.w. The main arsenic compound is arsenobetaine, which is widely considered as non-toxic. The exposure to toxic inorganic arsenic when eating whelks cannot be estimated from their size or their total arsenic concentration.     

Impacts of epigeic, anecic and endogeic earthworms on metal and metalloid mobility and availability

The introduction of earthworms into soils contaminated with metals and metalloids has been suggested to aid restoration practices. Eisenia veneta (epigeic), Lumbricus terrestris (anecic) and Allolobophora chlorotica (endogeic) earthworms were cultivated in columns containing 900 g soil with 1130, 345, 113 and 131 mg kg(-1) of As, Cu, Pb and Zn, respectively, for up to 112 days, in parallel with earthworm-free columns. Leachate was produced by pouring water on the soil surface to saturate the soil and generate downflow. Ryegrass was grown on the top of columns to assess metal uptake into biota. Different ecological groups affected metals in the same way by increasing concentrations and free ion activities in leachate, but anecic L. terrestris had the greatest effect by increasing leachate concentrations of As by 267%, Cu by 393%, Pb by 190%, and Zn by 429% compared to earthworm-free columns. Ryegrass grown in earthworm-bearing soil accumulated more metal and the soil microbial community exhibited greater stress. Results are consistent with earthworm enhanced degradation of organic matter leading to release of organically bound elements. The degradation of organic matter also releases organic acids which decrease the soil pH. The earthworms do not appear to carry out a unique process, but increase the rate of a process that is already occurring. The impact of earthworms on metal mobility and availability should therefore be considered when inoculating earthworms into contaminated soils as new pathways to receptors may be created or the flow of metals and metalloids to receptors may be elevated.     

高效液相色谱-原子荧光光谱联用测定水中形态砷

采用高效液相色谱-氢化物发生-原子荧光光谱联用技术测定水中亚砷酸盐[As(Ⅲ)]、二甲基砷(DMA)、一甲基砷(MMA)和砷酸盐[As(V)]等4种形态砷,以磷酸盐缓冲溶液为流动相,硼氢化钾为还原剂,优化了仪器主要技术参数.As(Ⅲ)、DMA、MMA和As(V)在7 min内实现了良好的基线分离,在5.00 μg/L～...     

Spatiotemporal distribution of arsineic species of oysters (Crassostrea gigas) in the coastal area of southwestern Taiwan

This study investigated total arsenic (As) and As species contents of oysters (Crassostrea gigas) in different production areas, seasons and sea locations on the southwestern coast of Taiwan. Analytical results indicate that contents of total As, arsenite, arsenate, dimethylarsinic acid, monomethylarsonic acid and arsenobetaine in oysters are 9.90 ± 3.68, 0.091 ± 0.104, 0.033 ± 0.038, 0.529 ± 0.284, 0.037 ± 0.046 and 3.94 ± 1.33 mg/g (dry wt), respectively. A ratio of inorganic As concentrations to total As concentrations is 1.26%. Total As contents of oysters cultured in the outer sea are statistically significantly lower than those of oysters cultured in the inner sea. The total As contents of oysters is the highest in Putai, where the blackfoot disease prevails. The low As contents in oysters is attributed to the low temperature in winter, which slows the metabolism of oysters. A maximum value is 33.37 μg/g (dry) in Putai in spring, because a considerable amount of aquacultural waste water with high As contents is discharged into adjacent drainage channels and rivers there during that season.     

Monitoring the species of arsenic, chromium and nickel in milled coal, bottom ash and fly ash from a pulverized coal-fired power plant in western Canada

The concentration of As, Cr and Ni and their speciation (As3+;5+, Cr3+;6+ and Ni0;2+) in milled coal, bottom ash and ash collected by electrostatic precipitator (ESP) from a coal fired-power plant in western Canada were determined using HGAAS, ICP-AES and XANES. The chemical fractionation of these elements was also determined by a sequential leaching procedure, using deionized water, NH4OAC and HCI as extracting agents. The leachate was analyzed by ICP-AES. Arsenic in the milled coal is mostly associated with organic matter, and 67% of this arsenic is removed by ammonium acetate. This element is totally removed from milled coal after extraction with HCI. Arsenic occurs in both the As3+ and the As5+ oxidation states in the milled coal, while virtually all (>90%) of the arsenic in bottom ash and fly ash appears to be in the less toxic arsenate (As5+) form. Both Ni and Cr in the milled coal are extracted by HCI, indicating that water can mobilize Ni and Cr in an acidic environment. The chromium is leached by water from fly ash as a result of the high pH of the water, which is induced during the leaching. Ammonium acetate removes Ni from bottom ash through an ion exchange process. Chromium in milled coal is present entirely as Cr3+, which is an essential human trace nutrient. The Cr speciation in bottom ash is a more accentuated version of the milled coal and consists mostly of the Cr3+ species. Chromium in fly ash is mostly Cr3+, with significant contamination by stainless-steel from the installation itself.