Arsenic Emissions Research Articles

Sampling technologies and air pollution control devices for gaseous and particulate arsenic: a review

Direct measurement of arsenic release requires a good sampling and analysis procedure in order to capture and detect the total amount of metals emitted. The literature is extensively reviewed in order to evaluate the efficiency of full field-scale and laboratory scale techniques for capturing particulate and gaseous emissions of arsenic from the thermo-chemical treatment of different sources of arsenic. Furthermore, trace arsenic concentrations in ambient air, national standard sampling methods and arsenic analysis methods are considered. Besides sampling techniques, the use of sorbents is also reviewed with respect to both approaches (1) to prevent the metals from exiting with the flue gas and (2) to react or combine with the metals in order to be collected in air pollution control systems. The most important conclusion is that submicron arsenic fumes are difficult to control in conventional air pollution control devices. Complete capture of the arsenic species requires a combination of particle control and vapour control devices.

Estimate of arsenic emission amount from the coal power stations in china

To study the amount of arsenic emission from the coal power stations (mainly Permo-Carboniferous coal) in China in different combustion conditions, the arsenic content of the coal, the fly ash and the cinder in high-temperature power stations as well as mid-low temperature power stations have been analyzed. This note provides a rough estimate of the total amount of arsenic emission as well as emission ratio from steam coal combustion in China. The results show that by combustion of 1 t of Permo-Carboniferous coal (containing roughly 5 mg/kg arsenic), high-temperature power stations emit roughly 0.40 g arsenic into the atmosphere and the arsenic emission rate is about 7.70%; mid-low power stations emit roughly 0.15 g arsenic into the atmosphere and the arsenic emission rate is about 2.97%. A total of 600 million tons coal is burnt annually in China power stations, and the coal comes mainly from Permo-Carboniferous depositing in the North China Plate and northwest China coal mines. Taking the average arsenic content of the coal used at the value of 5 mg/kg, the total annual arsenic emission from steam coal combustion into the atmosphere is about 195.0 t. Most of the arsenic in coal can be released in the process of coal combustion, and the most of the released arsenic can be seized by the fly ash and then both of them are seized by the dust catcher of power station, so the arsenic emission ratio to the atmosphere is declined; in addition, research on the arsenic emission amount and emission rules from the coal power stations in China should go on the coal power stations with the dry-process dust catchers by the experiments results. In the wet process of dust catcher, 20% of the arsenic in the fly ash is dissolved in the water of sedimentation tank in high-temperature power station; in the mid-low temperature power station there are 70% of the arsenic in the fly ash dissolved in the water of sedimentation tank, this is an important source of arsenic pollution in environment and should not be overlooked. The arsenic emission rate in the process of coal cineration in the laboratory is higher than the actual arsenic emission rate of power station.

Characterization of Arsenic Emissions from a Coal-Fired Power Plant

An emissions study for arsenic was conducted at a 300-MW coal-fired plant that was equipped with an electrostatic precipitator (ESP). The input and output streams, such as coal, slag, ESP ash, and flue gas that contained the post-ESP particulates, were collected. Gaseous arsenic was sampled using United States Environmental Protection Agency (USEPA) Method 29, and the arsenic concentrations in the samples were measured using inductively coupled plasma−atomic emission spectrometry. The mass balance recovery of arsenic estimated in this study was 87.2%. The arsenic concentration in the stack gas was 2.5 μg/Nm3. Approximately 0.53% of the coal-derived arsenic was incorporated into slag, 84.6% of the arsenic was found on the fly ash that was collected by the ESPs, and 2.16% was found in the vapor phase. The relationship between arsenic concentration and ash particle size was also assessed, and arsenic was significantly concentrated in the small-sized particles. The modes of occurrence of arsenic in ash samples were studied using a modified sequential chemical extraction method. The extractable fraction was 13.78%−25.27% of the total arsenic in the fly ash particles, from the four ESP hopper samples. The arsenic concentrations found in the different extraction fractions were as follows: 74.73%−86.22% in the residue; 11%−19% in carbonate-bound, surface oxide-bound ions; 2.7%−6.0% in readily extractable ions; and 0.076−0.27% in water-extractable form. There were no appreciable differences in the arsenic solubility fractions between the different particle sizes of fly ash.

Cumulative metal leaching from utilisation of secondary building materials in river engineering

The present paper estimates the utilisation of bulky wastes (minestone, steel slag, phosphorus slag and demolition waste) in hydraulic engineering structures in Dutch parts of the rivers Rhine, Meuse and Scheldt over the period 1980-2025. Although they offer several economic, technical and environmental benefits, these secondary building materials contain various metals that may leach into river water. A leaching model was used to predict annual emissions of arsenic, cadmium, copper, chromium, lead, mercury, nickel and zinc. Under the current utilisation and model assumptions, the contribution of secondary building materials to metal pollution in Dutch surface waters is expected to be relatively low compared to other sources (less than 0.1% and 0.2% in the years 2000 and 2025, respectively). However, continued and widespread large-scale applications of secondary building materials will increase pollutant leaching and may require further cuts to be made in emissions from other sources to meet emission reduction targets and water quality standards. It is recommended to validate available leaching models under various field conditions. Complete registration of secondary building materials will be required to improve input data for leaching models.

Estimate of arsenic emission amount from the coal power stations in China

Estimate of arsenic emission amount from the coal power stations in China

Arsenic biomonitoring using a hyperaccumulator fern (Pteris vittata).

Samples of Pteris vittata L. (brake fern or ladder brake) collected in Genova and in areas outside urban centres, have been analysed for arsenic content in order to assess if hyper accumulating plants are suitable for monitoring purposes. Hyper accumulation ability of the Ligurian fern populations was evaluated by analysing specimens grown with hydroponic media added with As(v). Arsenic concentrations in the range 2-310 microg g(-1) dry weight have been measured in samples collected in different sites along the Ligurian coast. Arsenic concentrations in fern fronds correlate with the estimated arsenic emission in the area, verifying the applicability of P. vittata as an arsenic biomonitor.

Metal Retention in the Solid Residue after Low-Temperature Pyrolysis of Chromated Copper Arsenate (CCA)-Treated Wood

Based on previous research work, it is expected that dry recuperation of the metals in chromated copper arsenate (CCA)-treated wood waste can be achieved by low-temperature pyrolysis if a combination of pyrolysis temperature and residence time can be found, for which the two requirements: (1) zero-emission of metals, and (2) metal agglomeration are satisfied. To determine the working conditions for zero metal release, pyrolysis experiments with precisely controlled temperature and residence time and accurately known input metal concentrations of the CCA-treated wood samples, were conducted. Temperatures lower than 327°C are considered, since the release of arsenic is thought to be controlled by the reduction reaction of As2O5 to As2O3, which occurs sharply at 327°C. Metal retentions are calculated based on the measured metal concentrations in the pyrolysis residue and in the dried CCA-treated wood. The results suggest that pyrolysis at 300°C for 20 min gives rise to zero release for the three metals (Cr, Cu, and As), while pyrolysis at 320°C leads to nonnegligible metal releases. Thus, the experimental results suggest that the decomposition temperature of As2O5 is lower than 320°C. However, due to the high experimental uncertainty the observations are inconclusive. For future industrial applications, this study already shows that very careful control of process parameters will be required to ensure a zero arsenic emission. Moreover, this study indicates that an arsenic sampling and analysis method has to be developed and validated to be able to measure the arsenic emissions directly with high accuracy, instead of measuring metal retentions in the solid residue.

Assessment of global industrial-age anthropogenic arsenic contamination

Arsenic, a carcinogenic trace element, threatens not only the health of millions of humans and other living organisms, but also global sustainability. We present here, for the first time, the global industrial-age cumulative anthropogenic arsenic production and its potential accumulation and risks in the environment. In 2000, the world cumulative industrial-age anthropogenic arsenic production was 4.53 million tonnes. The world-wide coal and petroleum industries accounted for 46% of global annual gross arsenic production, and their overall contribution to industrial-age gross arsenic production was 27% in 2000. Global industrial-age anthropogenic As sources (as As cumulative production) follow the order: As mining production>As generated from coal>As generated from petroleum. The potential industrial-age anthropogenic arsenic input in world arable surface in 2000 was 2.18 mg arsenic kg(-1), which is 1.2 times that in the lithosphere. The development of substitute materials for arsenic applications in the agricultural and forestry industries and controls of arsenic emissions from the coal industry may be possible strategies to significantly decrease arsenic pollution sources and dissipation rates into the environment.

Association between arsenic exposure from a coal-burning power plant and urinary arsenic concentrations in Prievidza District, Slovakia.

To assess the arsenic exposure of a population living in the vicinity of a coal-burning power plant with high arsenic emission in the Prievidza District, Slovakia, 548 spot urine samples were speciated for inorganic As (Asinorg), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), and their sum (Assum). The urine samples were collected from the population of a case-control study on nonmelanoma skin cancer (NMSC). A total of 411 samples with complete As speciations and sufficient urine quality and without fish consumption were used for statistical analysis. Although current environmental As exposure and urinary As concentrations were low (median As in soil within 5 km distance to the power plant, 41 micro g/g; median urinary Assum, 5.8 microg/L), there was a significant but weak association between As in soil and urinary Assum(r = 0.21, p < 0.01). We performed a multivariate regression analysis to calculate adjusted regression coefficients for environmental As exposure and other determinants of urinary As. Persons living in the vicinity of the plant had 27% higher Assum values (p < 0.01), based on elevated concentrations of the methylated species. A 32% increase of MMA occurred among subjects who consumed homegrown food (p < 0.001). NMSC cases had significantly higher levels of Assum, DMA, and Asinorg. The methylation index Asinorg/(MMA + DMA) was about 20% lower among cases (p < 0.05) and in men (p < 0.05) compared with controls and females, respectively.

Environmental Fate of Gallium Arsenide Semiconductor Disposal

SummaryThis article describes a methodology for the quantitative assessment of the environmental fate of gallium and arsenic from the disposal of mobile phones containing gallium arsenide (GaAs) semiconductors, using data from Japan.The product lifetime of mobile phones is short, and the recycling systems for such phones are currently underdeveloped. As a result, many mobile phones are disposed of via incineration and landfilling. The disposal of GaAs semiconductors could lead to some releases of gallium and arsenic to air and water. The methodology presented here begins with an estimation of the cumulative number of disposed mobile phones, using a logistic curve. Then, thermodynamic simulation and laboratory experiments are carried out to assess how much gallium and arsenic may be released into the environment. Using this method, the cumulative number of mobile phones disposed of in Japan is calculated to be 610 million by 2010. Distribution among air emissions, the leachate, and the insoluble residue (in landfilled incinerator ash) was determined to be 4.20 × 10‐2%, 1.58 × 10‐1%, and 99.8% for gallium, and 2.00 × 10‐1%, 19.5%, and 80.3% for arsenic, respectively. For phones that are disposed of directly in landfills, it is estimated that nearly 100% of the gallium and arsenic exists as the insoluble residue. We suggest that, in the conditions present in Japan, disposal of mobile phones directly into the landfill is preferable to the incineration with subsequent landfill of ash with respect to gallium and arsenic emissions into the environment. The proposed methodology may be adapted for the assessment of the environmental fate of problematic substances from the disposal of similar products.

Development of a sampling train for arsenic in pyrolysis vapours resulting from pyrolysis of arsenic containing wood waste.

In the present study a sampling and analysis method for arsenic emissions during pyrolysis of arsenic containing wood, such as chromated copper arsenate (CCA) treated wood, has been developed. The procedure is based on the NIOSH (National Institute for Occupational Safety and Health) standard for arsenic trioxide sampling. Validation for this specific application is needed since pyrolysis of arsenic containing wood leads to a gas stream containing sticky tar compounds and aerosols. Validation was carried out through tube furnace experiments using both CCA treated wood and arsenic trioxide powder as input. The outlet of the tube furnace was coupled to a cooling section and sampling train. The sampling train consisted of one or more filter sections and impingers. Different combinations of filters (untreated or impregnated) and impingers, as well as different combinations of washing solutions were tested. The different units of the sampling train were analysed by inductively coupled plasma mass spectrometry (ICP-MS) in order to determine the distribution of arsenic over the different units. For the working conditions considered (pyrolysis at 350 degrees C for 20 minutes with a nitrogen flow rate of 100 Nl h(-1)) the combination of a quartz cooling tube and a cellulose ester membrane filter impregnated with a Na2CO3-glycerol solution was sufficient to capture the arsenic. Two extra impingers (the first one containing 50 ml HNO3 1 M in the case of CCA treated wood and 50 ml NaOH 0.1 M in the case of As2O3 and the second one containing 50 ml NaOH 0.1 M) were added downstream of the filter section as backup either in case of filter failure or to check whether all the arsenic released is captured by the cooling tube and filter.

Anthropogenic and natural levels of arsenic in PM10 in Central and Northern Chile

A few copper and gold smelters in Chile are behind a large fraction of global arsenic emissions, raising concerns for increased concentrations of arsenic in PM10 in Central and Northern Chile. This concern is amplified by the fact that Northern Chile soils and rivers in general are characterized by a high arsenic content. A monitoring and modeling study has been performed to quantify the regional impact of the smelter emissions. Measured atmospheric arsenic concentrations from 2.4 to 30.7 ng m −3 were found at seven rural stations, located tens to hundreds of kilometers away from the nearest smelter. Analyses of topsoil and subsoil samples taken from PM10 monitoring stations revealed levels up to 291 mg kg −1, the highest values found in the northern Atacama desert in Chile. An absolute principal component analysis of selected trace elements in PM10 shows that the regional impact of anthropogenic smelter emissions on airborne arsenic concentrations is more important than the effect of soil dust resuspension. The dominance of the smelter emissions is larger in Central Chile than in the northern parts. The impact of resuspended soil dust on airborne arsenic levels in rural areas was estimated not to exceed 5 ng m −3. The model calculations support the dominant role of anthropogenic emissions and give spatial and temporal variations in atmospheric concentrations consistent with the monitored levels at five of the seven stations. At two of the northernmost stations indications were found of unidentified sources other than the smelters and the resuspended soil dust, contributing to about 5 ng m −3 of total arsenic levels. The study confirms that a strong control or elimination of arsenic emissions from the smelters would lead to arsenic in PM10 levels in Northern and Central Chile comparable to non-polluted areas in other countries.

Assessment of environmental arsenic levels in Prievidza district.

A coal-burning power station in the Nitra Valley in central Slovakia annually emitted large quantities of arsenic (up to 200 tonnes) between 1953 and 1989. Since then, pollution-control measures have reduced arsenic emissions to less than 2 tonnes a year. However, the power station was still a source of airborne arsenic pollution. As part of an EU-funded study on exposure to arsenic and cancer risk in central and Eastern Europe we carried out a study of environmental levels of arsenic in the homes and gardens of residents of the district. Garden soil samples (n=210), house dust samples (n=210) and composite house dust samples (n=109) were collected and analysed using inductively coupled plasma atomic absorption spectroscopy (ICP-AES) at Imperial College. The mean arsenic content of coal and ash in samples taken from the plant was 519 microg/g (n=19) and 863 microg/g (n=22), respectively. The geometric mean (GM) arsenic concentration of garden soils was 26 microg/g (range 8.8-139.0 microg/g), for house dust 11.6 microg/g (range 2.1-170 microg/g) and for composite house dust 9.4 microg/g (range 2.3-61.5 microg/g). The correlation between the arsenic levels in soil and in house dust was 0.3 (P<0.01), in soil and composite house dust 0.4 and house dust and composite house dust 0.4 (P<0.01 for both), i.e., were moderate. Arsenic levels in both house dust and soil decreased with distance from the power station. Overall, levels in both fell by half 5 km from the point source. Weak correlations were seen between the total urinary arsenic concentrations and arsenic concentrations in composite house dust.

Comparative Life Cycle Assessment of flooring materials: ceramic versus marble tiles

Flooring materials, particularly ceramic and marble tiles, play a relevant role in the Italian economy since this country covers respectively 23% and 18% of the world output in this sector. In this paper a comparative Life Cycle Assessment between these two flooring materials has been carried out in order to identify the one with the best environmental profile and the hot spots of the two systems. The analysis has shown a better environmental profile for the marble tile, a particular relevance of the energy consumption in both the system and, in the ceramic system, the critical point has been found in the raw material used for the glaze manufacturing which are responsible, during the firing process, for the relevant arsenic emissions.

Atmospheric Emissions, Depositions, and Transformations of Arsenic in Natural Ecosystem in Finland

For the last 2 decades, special attention has been paid to arsenic due to its high concentration in groundwater in many regions of the globe. There are not very many reports on arsenic concentration in the Finnish ecosystem, although the metal has been known to be highly toxic since ancient times. For the majority of people in Finland, the leading exposure route to arsenic is through food consumption.In this study, it has been observed that atmospheric emissions of arsenic from anthropogenic sources have decreased by 90%, which is due to better control technology and strict regulation. Aquatic discharge also was attenuated from 7.1 metric tons (t) in 1990 to 0.7 t in 1999. The concentration of arsenic aerosols in the atmosphere in Finland varies between 0.46 to 0.75 ng m–3. Its use in pesticides and insecticides also has been phased out in Finland. There is no information available regarding arsenic species in the Finnish environment.Elevated concentrations of arsenic in groundwater has been reported for many countries. In Finland two hot spots are reported – one in the south of Finland and the second in Lapland. In these areas, arsenic concentration in well water is greater than 10 μg l–1 (WHO recommended value: <10 μg l–1). It is believed that the release of arsenic into the Finnish groundwater is geogenic.

A Thermodynamic Equilibrium Analysis to Determine the Potential Sorbent Materials for the Control of Arsenic Emissions from Combustion Sources

Equilibrium analyses are carried out to determine the potential sorbent materials for effective chemisorption of arsenic in combustion systems. Al-, Fe-, Li-, Na-, K-, Be-, Mg-, Ca-based sorbents are found to be effective. Excellent removal of arsenic is achieved in a wide range of temperatures. However, the effectiveness of these sorbents may be reduced when chlorine or sulfur is present in the system. The presence of chlorine in the system greatly reduces the performance of alkali metal and Fe-based sorbents due to the formation of chlorides. The impact of chlorine on alkaline earth metal and Al-based sorbents is found to be less significant. The presence of sulfur reduces the effectiveness of most sorbents due to the formation of sulfates. The only exception is Al-based sorbent. The affinity to adsorb arsenic generally follows the order: Li > K > Na > Al > Ca > Mg > Fe > Be, if there is no chlorine or sulfur in the system. However, the order of effectiveness will be altered if chlorine or sulfur is present in the system. The analyses establish the understanding of how various parameters affect the effectiveness of the sorption process.

Use of Neutron Activation Analysis to Determine Arsenic and Antimony Concentrations in Creosote Bushes Collected Near a Lead Smelter in El Paso, Texas

El Paso, Texas continues to be a city with environmental concerns particularly for air quality. Both the US Environmental Protection Agency and the Texas Natural Resource Conservation Center have major programs to monitor the unusually high concentration of airborne particles that affect the general population. El Paso, being a border city is also affected by trans border air pollution. One research area that has seen increased visibility involves those industries that can adversely affect both air and soil. Smelters are a prime example of this emissions phenomenon. Typically in the smelting process, arsenic is a natural byproduct of ore processing to extract lead and copper. While processing these ores, arsenic as well as lead, copper, and other elements gain access to the environment through air deposition. Therefore, in areas near smelter activity, arsenic and other heavy metals emissions, can be found and can be a potential serious health concern. Recently the United Nations has proclaimed that as many as 45 million people living in Bangladesh may be at serious health risk from natural contamination of aquifers from arsenic. There have been many published data on elevated concentrations of heavy metals in soil resulting from smelter activities.1–4 Migration of lead from shotgun pellets to humus and plant species at a firing range has also been studied.5 It has been found that some soils adjacent to a lead smelter in El Paso, Texas possess lead and copper concentrations as high as 5,067 mg/kg (parts per million) and 4,955 mg/kg, respectively.6 These concentrations are at least one order of magnitude higher than naturally occurring levels. At present, there are no data reported on the distribution of arsenic concentrations in this area and no information on the uptake of arsenic and antimony by native vegetation. Vegetation may also be an ideal mechanism to bio-remediate soil and can be a natural and inexpensive way to clean up contaminated sites. Therefore, a preliminary investigation into the distribution of the arsenic, its depth in the soil as well as its potential for vegetation uptake would be of great environmental and remediation value. As well, it is known that antimony is a hardener used in lead processing and its determination would also be of value. We report herein the use of neutron activation analysis to determine arsenic and antimony concentrations in creosote bushes and soil samples.

Determination of inorganic and organic anionic arsenic species in water by ion chromatography coupled to hydride generation–inductively coupled plasma atomic emission spectrometry

The development of an analytical methodology for the specific determination of arsenite, arsenate and the organic species monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA), is described. The method is based on an ion chromatographic separation, coupled on-line to post-column generation of the gaseous hydrides by reaction with sodium tetrahydroborate in acidic medium. Detection and measurement were performed by inductively coupled plasma spectrometry operated in the atomic emission mode. Arsenic emission was monitored at 193.7 nm. Different types and sizes of anion-exchange columns, silica and polymeric, were tested using EDTA as eluent. Composition, acidity and flow-rate of the mobile phase were optimized in order to obtain the required resolution. Complete elution and resolution of the four species was achieved in about 6 min. Linear calibration curves were obtained in the 0.05–2 μg ml −1 range for As(III), As(V) and MMA, and between 0.1 and 2.0 μg ml −1 for DMA. The absolute limits of detection for 200-μl sample injections were in the ng range, with DMA the compound measured with less sensitivity. Results of the analyses of natural samples, such as river and ground waters spiked with the studied species, suggested that analyte recoveries might be dependent on the sample composition.

Measurement of Arsenic Emission from Doped Czochralski Silicon Crystal Growing Operation

AbstractThe level of arsenic from the effluent of a crystal grower was measured at different phases of the silicon crystal growth operation which includes arsenic doping, crystal body growth, burn‐in, and post burn‐in periods. Measurement of arsenic levels were made in the discharge water used as the sealing liquid for the liquid ring vacuum pump used for process effluent discharge. Gas phase measurements were also performed for both particulate arsenic as As2O3 as well as for compounds of arsenic in vapor phase as AsH3. Results of these analyses provided important information for developing strategy for emission treatment and control, reducing arsenic exposure to personnel and evaluating the feasibility for recycling argon used in the crystal growing process.

Soft laser sputtering of GaAs semiconductor (100) surface

We have studied the soft laser sputtering of (100)GaAs with 337 nm photons, starting from the threshold for particle emission (a few tens of mJ/cm2) to some 300 mJ/cm2 fluences. Atoms and molecules sputtered from the irradiated surface are detected, their relative number measured, and their time of flight determined using laser resonant ionization mass spectrometry. The surface after laser irradiation is examined by scanning electron microscopy and electron microprobe analysis. One observes a significant preferential emission of arsenic in the form of As2. This leads to the formation of perturbed Ga-rich surface structure which appears even at low fluence and after a few tens of laser shots on the same spot. This initial transformation seems to determine the further evolution of the irradiated surface. First, Ga atoms aggregate to form Ga islands on the surface; after a sufficient number of shots, micrometric structures are produced which finally behave as pure Ga metal. This evolution of the surface state after multipulse irradiation appears practically the same for low and medium laser fluences, the only difference being in the number of shots required to obtain the same microscopic structure. The velocity distribution of Ga atoms and As2 molecules is well fitted by half-space Maxwellian distributions. The kinetic temperatures are in broad agreement with the results obtained from a model of laser heating of the surface. The gross features of the experimental results can be interpreted from the particular thermodynamics properties of GaAs which exhibits very large As2 pressure above the solid as soon as the temperature exceeds 950 K. After a few laser shots, corresponding to particle emission from defect sites, the thermodynamics of GaAs appears to govern the further evolution of the laser-sputtered surface. Two sputtering regimes are evidenced: In the low-fluence regime (from threshold to 90 mJ/cm2) sputtering appears to be dominated by surface defect emission, whereas for higher fluences emission is more characteristic of thermal process accompanied by preferential sputtering of arsenide. According to these experimental results, a simple analytical model was developed which relates the quantitative surface to the quantitative sputtered cloud compositions.