Environmental levels of cadmium and lead in the vicinity of a major refuse incinerator

This study examines whether the atmospheric release of Cd and Pb from a refuse incinerator in London has caused contamination of the local environment. Sampling networks were established for street dusts, surface soils, vegetation and total deposit gauges in areas up to 5 km downwind and upwind from the incinerator. Measurements of Cd and Pb indicate there is neither a marked nor an extensive contamination by these metals in the downwind area. However, dust Cd values decreased with distance from the incinerator in this area and Cd deposition rates were higher than in the upwind area. Nevertheless, most Cd values obtained in the downwind area were similar to those previously reported for other parts of London while Pb values were often lower. It is considered that the 100 m stack of the incinerator minimizes the deposition of particulate emissions in the vicinity of this source. Appreciable Cd contamination was found within the grounds of the incinerator, the values being about 4–50-fold higher than in either the upwind or downwind areas. The extent of Pb contamination in this small area was more limited, with values being about twice those found in the two study areas. The source of this contamination is ascribed to fugitive releases arising from the storage and transport of the ashes produced by the incinerator.     

Particulate size distributions and mass measured at a motorway during the BAB II campaign

From 1 May to 25 May 2001, the BAB II campaign was carried out at the motorway BAB (656) near Heidelberg. Atmospheric concentrations of particulate matter and gases were measured together with the meteorological conditions. This paper is focused on the particulate matter measured upwind and downwind from the motorway at ground level. In order to determine the source contribution from the motorway traffic, it was necessary to measure upwind and downwind simultaneously due to variations in background concentrations. The particle number contribution from the motorway was found to be 35,000 particles cm⁻³ for particles with diameters close to 20 nm and 5000 particles cm⁻³ for particles with diameters close to 70 nm. Bimodal size distributions were observed on the downwind side, whereas the upwind side showed unimodal size distributions. For particulate mass, it can be estimated that the contribution from the motorway to the PM₁ concentrations is in a range 0.6–1.3 μg m⁻³ for the chosen measurement sites approximately 60 m from the road at a height of 6 m. The soot measurements showed diurnal variation; however, the upwind downwind difference was not measured. Correlation factors showed good correlation between total particle number and number of particles with diameters below 80 nm, CO and NO. There was no correlation between particle number and PM₁₀, which is due to the observation that particle number was dominated by the 20 nm particles.     

Concentrations of particulate matter emitted from large cattle feedlots in Kansas

Particulate matter (PM) emitted from cattle feedlots are thought to affect air quality in rural communities, yet little is known about factors controlling their emissions. The concentrations of PM (i.e., PM2.5, PM10, and total suspended particulates or TSP) upwind and downwind at two large cattle feedlots (KS1, KS2) in Kansas were measured with gravimetric samplers from May 2006 to October 2009 (at KS1) and from September 2007 to April 2008 (at KS2). The mean downwind and net (i.e., downwind - upwind) mass concentrations of PM2.5, PM10, and TSP varied seasonally, indicating the need for multiple-day, seasonal sampling. The downwind and net concentrations were closely related to the moisture content of the pen surface. The PM2.5/PM10 and PM2.5/TSP ratios at the downwind sampling location were also related to the moisture content of the pen surface, humidity, and temperature. Measurement of the particle size distribution downwind of the feedlot with a cascade impactor showed geometric mean diameter ranging from 7 to 18 microm, indicating that particles that were emitted from the feedlots were generally large in size.     

A New Method for Determining the Contribution of a Refinery to Local SO2 Levels in an Industrial Region

A new method was developed for determining the contribution of one pollutant source to the air quality in an industrialized region. Although the method is general, it is presented in reference to a 130,000 bbl/day petroleum refinery and its effect on ambient SO₂ concentrations in Sarnia, Ontario. The plumes from SO₂ emitters located upwind of the refinery were represented by a single hypothetical plume which influences monitoring stations located upwind as well as downwind from the refinery. However, the refinery emissions affect only the downwind stations. A simple equation was derived by means of which the concentration at the downwind station could be calculated from the concentration at the upwind station and the refinery emission. This equation contains two coefficients A and B which were evaluated such that the difference between the cumulative frequency distributions of the measured and calculated SO₂ concentrations at the downwind station was minimized. For the meteorological conditions and monitoring stations considered, it was found that the refinery contributed less than 4.5 pphm to ambient SO₂ concentrations over 1 hr periods. This result and the validity of the method are discussed.     

Roadside particle number distributions and relationships between number concentrations, meteorology, and traffic along a northern California freeway

Particle number distributions were measured simultaneously upwind and downwind of a suburban-agricultural freeway to determine relationships with traffic and meteorological parameters. Average traffic volumes were 6330 vehicles/hr with 10% heavy-duty vehicles, and volumes were higher in July than November. Most downwind particle number distributions were bimodal, with a primary mode at approximately 10-25 nm, indicating that newly formed particles were sampled. Total downwind 6-237 nm particle number concentrations (Ntot) ranged from 9.3 x 10(3) to 2.5 x 10(5) cm(-3), with higher daily average concentrations in November compared with July. Ntot correlated with wind speed, temperature, and relative humidity. Upwind photochemically initiated nucleation likely led to elevated background nanoparticle concentrations in July, as evidenced by increasing upwind distribution modal diameter with increasing temperature and a strong correlation between upwind Ntot and solar radiation. Also in summer, Ntot showed stronger correlation with heavy-duty vehicle volumes than wind speed, temperature, and relative humidity. These results indicate the importance of measuring background particle size distributions simultaneously with roadside distributions. There may be a minimum vehicle volume from which useful real-world vehicle particle number distributions can be measured at roadside, even when collecting samples within 10 m of the traveled lanes.     

The Evolution of Visibility Deterioration and Aerosol Spectra in the St. Louis Urban Plume

Under the auspices of Project METROMEX, studies of visibility de-teoration downwind of St. Louis were conducted during July-August 1974-1975. Estimates of horizontal visual range, standard meteorological data, and aerosol characteristics within the mixing layer were acquired upwind, over, and downwind of the metropolitan area by means of airborne transects. Aerosol number, surface, and volume distributions for particles between 0.025-2.5 µm were generated from the airborne measurement of Aitken nucleus concentrations, cloud condensation nuclei, and aerosols detected in situ with optical probes. Visibility reduction amounting to 50% of prevailing regional upwind visibilities consistently occurs at a distance corresponding to 2-3 hours travel time downwind for an air parcel moving with the mean transport wind. The regions of visibility minimum do not coincide with locations of maximum Aitken nucleus concentrations, but rather correspond in space and time to increased values of cloud condensation nuclei and increased numbers of particles in the 0.1-2.5 µm diameter range. Comparisons of observed aerosol evolution with similar laboratory studies suggest that most of the light scattering aerosols are of secondary origin.     

Study on the formation and transport of ozone in relation to the air quality management and vegetation protection in Tenerife (Canary Islands)

An experimental study on the formation and transport of ozone in ambient air was performed in Tenerife (Canary Islands) in order to investigate the processes affecting ozone levels and air quality. The special features of Tenerife (prevalence of the trade wind pattern (NE), orography and the specific location of the local ozone sources) permit to quantify the role of the ‘long-range transport from northern latitudes' versus the ‘formation and transport of ozone downwind of the main urban areas' of Tenerife. Levels of O₃, NO₂ and O_X were monitored in different types of environments to achieve this purpose. The results showed that: (1) upwind of the urban areas ozone is mainly transported from the ocean by trade winds, (2) local ozone titration (by NO) and ozone replenishment from the ocean are the main causes of ozone variations in urban and suburban areas, and (3) photochemical ozone production occurs downwind of the urban areas. Photochemical production causes daylight O₃ and O_X levels downwind of urban areas to be frequently (60% and 35% days/year, respectively) higher than upwind of the urban sites (O₃ and O_X excess frequently in the range 5–20 ppbv). Due to the above processes, different daily ozone cycles occur in short distances (<30 km), with maximum O₃ levels during daylight or night depending on the site. Ozone phytotoxicity was assessed by calculating the AOT40 index upwind and downwind of the main urban areas. The critical value for the 5-day-AOT40 index was simultaneously exceeded at the two sites (few times/year) during long-range transport events. During the additional exceedances of the critical value downwind of the urban area, relatively high 5-day-AOT40 values were recorded upwind of the urban site. Thus, long-range transport from northern latitudes may produce relatively high 5-days-AOT40 levels in the oceanic boundary layer. These results are important for the protection of the large number of endemic plants in the Canaries. The conceptual model discussed in this study may be qualitatively applied to other islands which possess features similar to those of Tenerife.     

Ammonia flux from open-lot dairies: development of measurement methodology and emission factors

Ammonia emissions contribute to the formation of secondary particulate matter (PM) and violations of the National Ambient Air Quality Standard. Ammonia mass concentration measurements were made in February 1999 upwind and downwind of an open-lot dairy in California, using a combination of active bubbler and passive filter samplers. Ammonia fluxes were calculated from concentrations measured at 2, 4, and 10 m above ground at three locations on the downwind edge of the dairy, using micrometeorological techniques. A new method was developed to interpolate fluxes at six additional locations from ammonia concentrations measured at a single height, providing measurements at sufficient spatial resolution along the downwind border of the dairy to account for the heterogeneity of the source. PM measured up- and downwind of the dairy demonstrated insignificant ammonium particle formation in the immediate vicinity of the dairy and negligible contribution of dissociated ammonium nitrate to measured ammonia concentrations. Ammonium nitrate concentrations measured downwind of the dairy ranged from 26 to 0.26 microg m(-3) and from 2 to 43% of total PM2.5 mass concentrations. Measured ammonia fluxes showed that liquid manure retention ponds represented relatively minor sources of ammonia in winter on the dairy studied. Ammonia emission factors derived from the measurements ranged from 19 to 143 g head(-1) day(-1), showing an increase with warmer, drier weather and a decrease with increased relative humidity and lower temperatures.     

Potentially Allergenic Airborne Particles in the Vicinity of a Yeast and Penicillin Production Plant

Potential health risks of exposure to emissions of a yeast and penicillin production plant were investigated by measuring viable particles and protein contents of particles in ambient air. The results showed a clear decrease of the downwind number of yeast colonyforming units with increasing distance from the source. Upwind the number of yeast colony-forming units was zero. Identification showed that nearly all yeast were of the species Saccharomlces cerevisiae. Such a trend could not be found for the total number of colony-forming units (yeasts, molds, and bacteria) although the upwind concentration was slightly lower than the downwind concentration. The downwind protein concentration was significantly elevated compared to the upwind concentration.     

Concentration and size distribution of ultrafine particles near a major highway

Motor vehicle emissions usually constitute the most significant source of ultrafine particles (diameter <0.1 microm) in an urban environment, yet little is known about the concentration and size distribution of ultrafine particles in the vicinity of major highways. In the present study, particle number concentration and size distribution in the size range from 6 to 220 nm were measured by a condensation particle counter (CPC) and a scanning mobility particle sizer (SMPS), respectively. Measurements were taken 30, 60, 90, 150, and 300 m downwind, and 300 m upwind, from Interstate 405 at the Los Angeles National Cemetery. At each sampling location, concentrations of CO, black carbon (BC), and particle mass were also measured by a Dasibi CO monitor, an aethalometer, and a DataRam, respectively. The range of average concentration of CO, BC, total particle number, and mass concentration at 30 m was 1.7-2.2 ppm, 3.4-10.0 microg/m3, 1.3-2.0 x 10(5)/cm3, and 30.2-64.6 microg/m3, respectively. For the conditions of these measurements, relative concentrations of CO, BC, and particle number tracked each other well as distance from the freeway increased. Particle number concentration (6-220 nm) decreased exponentially with downwind distance from the freeway. Data showed that both atmospheric dispersion and coagulation contributed to the rapid decrease in particle number concentration and change in particle size distribution with increasing distance from the freeway. Average traffic flow during the sampling periods was 13,900 vehicles/hr. Ninety-three percent of vehicles were gasoline-powered cars or light trucks. The measured number concentration tracked traffic flow well. Thirty meters downwind from the freeway, three distinct ultrafine modes were observed with geometric mean diameters of 13, 27, and 65 nm. The smallest mode, with a peak concentration of 1.6 x 10(5)/cm3, disappeared at distances greater than 90 m from the freeway. Ultrafine particle number concentration measured 300 m downwind from the freeway was indistinguishable from upwind background concentration. These data may be used to estimate exposure to ultrafine particles in the vicinity of major highways.     

Characterization of spatial impact of particles emitted from a cement material production facility on outdoor particle deposition in the surrounding community

The objective of this study was to estimate the contribution of a facility that processes steel production slag into raw material for cement production to local outdoor particle deposition in Camden, NJ. A dry deposition sampler that can house four 37-mm quartz fiber filters was developed and used for the collection of atmospheric particle deposits. Two rounds of particle collection (3-4 weeks each) were conducted in 8-11 locations 200-800 m downwind of the facility. Background samples were concurrently collected in a remote area located -2 km upwind from the facility. In addition, duplicate surface wipe samples were collected side-by-side from each of the 13 locations within the same sampling area during the first deposition sampling period. One composite source material sample was also collected from a pile stored in the facility. Both the bulk of the source material and the < 38 microm fraction subsample were analyzed to obtain the elemental source profile. The particle deposition flux in the study area was higher (24-83 mg/m2 x day) than at the background sites (13-17 mg/m2day). The concentration of Ca, a major element in the cement source production material, was found to exponentially decrease with increasing downwind distance from the facility (P < 0.05). The ratio of Ca/Al, an indicator of Ca enrichment due to anthropogenic sources in a given sample, showed a similar trend. These observations suggest a significant contribution of the facility to the local particle deposition. The contribution of the facility to outdoor deposited particle mass was further estimated by three independent models using the measurements obtained from this study. The estimated contributions to particle deposition in the study area were 1.8-7.4% from the regression analysis of the Ca concentration in particle deposition samples against the distance from the facility, 0-11% from the U.S. Environmental Protection Agency (EPA) Chemical Mass Balance (CMB) source-receptor model, and 7.6-13% from the EPA Industrial Source Complex Short Term (ISCST3) dispersion model using the particle-size-adjusted permit-based emissions estimates.     

Emissions of polychlorinated biphenyls (PCBs) from sludge drying beds to the atmosphere in Chicago

Ambient air PCB concentrations in the Lake Calumet region in Southeast Chicago have been found to be significantly higher than in nearby non-urban areas. This area is highly industrialized and also contains municipal sludge drying facilities and landfills. In an effort to quantify the importance of the sludge drying facilities to the elevated concentrations, upwind/downwind air samples from the Calumet East sludge drying bed were obtained between April and October 2002. For these samples, the downwind minus upwind (downwind-upwind) concentration varied from 0.33 to 1.27ngm(-3) for non-northeast (NE) direction winds suggesting sludge drying is a source of PCBs to the atmosphere. However, the upwind concentrations were higher than the downwind for winds from the NE of the sampling site suggesting more significant source(s), possibly Lake Calumet or the so called "Cluster site" NE of the sludge drying beds. Flux chamber experiments carried out during the sampling period measured average PCB fluxes of 210ngm(-2)h(-1) (range 43-910ngm(-2)h(-1)) which resulted in an overall flux of 0.005kgday (d)(-1) ( approximately 2kgyr(-1)). A developed regression equation between moisture content and sludge concentration estimated higher PCB losses of 0.26kgd(-1) ( approximately 95kgyr(-1)). Although these two approaches yielded different values, they both indicate that the emission from the Calumet East sludge drying beds were of minimal importance when compared to the total estimated amount of 2-70kgd(-1) (700-2100kgyr(-1)) of PCBs entering the Chicago atmosphere.     

Ammonia Flux from Open-Lot Dairies: Development of Measurement Methodology and Emission Factors

Abstract

Ammonia emissions contribute to the formation of secondary particulate matter (PM) and violations of the National Ambient Air Quality Standard. Ammonia mass concentration measurements were made in February 1999 upwind and downwind of an open-lot dairy in California, using a combination of active bubbler and passive filter samplers. Ammonia fluxes were calculated from concentrations measured at 2, 4, and 10 m above ground at three locations on the downwind edge of the dairy, using micrometeorological techniques. A new method was developed to interpolate fluxes at six additional locations from ammonia concentrations measured at a single height, providing measurements at sufficient spatial resolution along the downwind border of the dairy to account for the heterogeneity of the source. PM measured up- and downwind of the dairy demonstrated insignificant ammonium particle formation in the immediate vicinity of the dairy and negligible contribution of dissociated ammonium nitrate to measured ammonia concentrations. Ammonium nitrate concentrations measured downwind of the dairy ranged from 26 to 0.26 μg m^?3 and from 2 to 43% of total PM_2.5 mass concentrations. Measured ammonia fluxes showed that liquid manure retention ponds represented relatively minor sources of ammonia in winter on the dairy studied. Ammonia emission factors derived from the measurements ranged from 19 to 143 g head^?1 day^?1, showing an increase with warmer, drier weather and a decrease with increased relative humidity and lower temperatures.     

Concentration and Size Distribution of Ultrafine Particles Near a Major Highway

Abstract

Motor vehicle emissions usually constitute the most significant source of ultrafine particles (diameter <0.1 μm) in an urban environment, yet little is known about the concentration and size distribution of ultrafine particles in the vicinity of major highways. In the present study, particle number concentration and size distribution in the size range from 6 to 220 nm were measured by a condensation particle counter (CPC) and a scanning mobility particle sizer (SMPS), respectively. Measurements were taken 30, 60, 90, 150, and 300 m downwind, and 300 m upwind, from Interstate 405 at the Los Angeles National Cemetery. At each sampling location, concentrations of CO, black carbon (BC), and particle mass were also measured by a Dasibi CO monitor, an aethalometer, and a DataRam, respectively. The range of average concentration of CO, BC, total particle number, and mass concentration at 30 m was 1.7?2.2 ppm, 3.4?10.0 μg/m³, 1.3?2.0 × 10⁵/cm³, and 30.2?64.6 μ/m³, respectively.

For the conditions of these measurements, relative concentrations of CO, BC, and particle number tracked each other well as distance from the freeway increased. Particle number concentration (6–220 nm) decreased exponentially with downwind distance from the freeway. Data showed that both atmospheric dispersion and coagulation contributed to the rapid decrease in particle number concentration and change in particle size distribution with increasing distance from the freeway. Average traffic flow during the sampling periods was 13,900 vehicles/hr. Ninety-three percent of vehicles were gasoline-powered cars or light trucks. The measured number concentration tracked traffic flow well. Thirty meters downwind from the freeway, three distinct ultrafine modes were observed with geometric mean diameters of 13, 27, and 65 nm. The smallest mode, with a peak concentration of 1.6 × 10⁵/cm³, disappeared at distances greater than 90 m from the freeway. Ultrafine particle number concentration measured 300 m downwind from the freeway was indistinguishable from upwind background concentration. These data may be used to estimate exposure to ultrafine particles in the vicinity of major highways.     

Demolition of high-rise public housing increases particulate matter air pollution in communities of high-risk asthmatics

Public housing developments across the United States are being demolished, potentially increasing local concentrations of particulate matter (PM) in communities with high burdens of severe asthma. Little is known about the impact of demolition on local air quality. At three public housing developments in Chicago, IL, PM with an aerodynamic diameter < 10 microm (PM10) and < 2.5 microm were measured before and during high-rise demolition. Additionally, size-selective sampling and real-time monitoring were concurrently performed upwind and downwind of one demolition site. The concentration of particulates attributable to demolition was estimated after accounting for background urban air pollution. Particle microscopy was performed on a small number of samples. Substantial increases of PM10 occurred during demolition, with the magnitude of that increase varying based on sampler distance, wind direction, and averaging time. During structural demolition, local concentrations of PM10 42 m downwind of a demolition site increased 4- to 9-fold above upwind concentrations (6-hr averaging time). After adjusting for background PM10, the presence of dusty conditions was associated with a 74% increase in PM10 100 m downwind of demolition sites (24-hr averaging times). During structural demolition, short-term peaks in real-time PM10 (30-sec averaging time) occasionally exceeded 500 microg/m(3). The median particle size downwind of a demolition site (17.3 microm) was significantly larger than background (3 microm). Specific activities are associated with realtime particulate measures. Microscopy did not identify asbestos or high concentrations of mold spores. In conclusion, individuals living near sites of public housing demolition are at risk for exposure to high particulate concentrations. This increase is characterized by relatively large particles and high short-term peaks in PM concentration.     

The Collection and Analysis of Inorganic Dust Downwind of Source Effluents

Two directionally oriented high-volume samplers are used to pinpoint the collection of specific inorganic dusts from an industrial emission. One of the samplers is placed upwind of the source, and the other downwind. Both samplers are activated by winds blowing from the direction of the source to the downwind sampler. Both are de-activated when the wind shifts from the 30° sampling arc. Thus, the upwind sampler “sees” background dust, and the downwind sampler “sees” material originating from the source. Microsorban filters are used to collect the dust materials. The filter is then dissolved in benzene and the residue washed with benzene to remove the filter material and organic substances collected. The residue consists of dry, inorganic dust, which is then subjected to X-ray diffraction and optical microscopy, for analysis. This technique was successfully used to collect and analyze cement dust and mica dust from two separate industrial sources. The technique has promise for the analysis of a wide variety of inorganic materials which can be identified by X-ray diffraction, optical microscopy or other techniques.     

Effects of wind direction on coarse and fine particulate matter concentrations in southeast Kansas

Field data for coarse particulate matter ([PM] PM10) and fine particulate matter (PM2.5) were collected at selected sites in Southeast Kansas from March 1999 to October 2000, using portable MiniVol particulate samplers. The purpose was to assess the influence on air quality of four industrial facilities that burn hazardous waste in the area located in the communities of Chanute, Independence, Fredonia, and Coffeyville. Both spatial and temporal variation were observed in the data. Variation because of sampling site was found to be statistically significant for PM10 but not for PM2.5. PM10 concentrations were typically slightly higher at sites located within the four study communities than at background sites. Sampling sites were located north and south of the four targeted sources to provide upwind and downwind monitoring pairs. No statistically significant differences were found between upwind and downwind samples for either PM10 or PM2.5, indicating that the targeted sources did not contribute significantly to PM concentrations. Wind direction can frequently contribute to temporal variation in air pollutant concentrations and was investigated in this study. Sampling days were divided into four classifications: predominantly south winds, predominantly north winds, calm/variable winds, and winds from other directions. The effect of wind direction was found to be statistically significant for both PM10 and PM2.5. For both size ranges, PM concentrations were typically highest on days with predominantly south winds; days with calm/variable winds generally produced higher concentrations than did those with predominantly north winds or those with winds from "other" directions. The significant effect of wind direction suggests that regional sources may exert a large influence on PM concentrations in the area.     

Air pollutant concentrations near three Texas roadways, part II: Chemical characterization and transformation of pollutants

Spatial gradients of vehicular emitted air pollutants were measured in the vicinity of three roadways in the Austin, Texas area: (1) State Highway 71 (SH-71), a heavily traveled arterial highway dominated by passenger vehicles; (2) Interstate 35 (I-35), a limited access highway north of Austin in Georgetown; and (3) Farm to Market Road 973 (FM-973), a heavily traveled surface roadway with significant truck traffic. A mobile monitoring platform was used to characterize the gradients of CO and NO_x concentrations with increased distance from each roadway, while concentrations of carbonyls in the gas-phase and fine particulate matter mass and composition were measured at stationary sites upwind and at one (I-35 and FM-973) or two (SH-71) downwind sites. Regardless of roadway type or wind direction, concentrations of carbon monoxide (CO), nitric oxide (NO), and oxides of nitrogen (NO_x) returned to background levels within a few hundred meters of the roadway. Under perpendicular wind conditions, CO, NO and NO_x concentrations decreased exponentially with increasing distance perpendicular to the roadways. The decay rate for NO was more than a factor of two greater than for CO, and it comprised a larger fraction of NO_x closer to the roadways than further downwind suggesting the potential significance of near roadway chemical processing as well as atmospheric dilution. Concentrations of most carbonyl species decreased with distance downwind of SH-71. However, concentrations of acetaldehyde and acrolein increased farther downwind of SH-71, suggesting chemical generation from the oxidation of primary vehicular emissions. The behavior of particle-bound organic species was complex and further investigation of the size-segregated chemical composition of particulate matter (PM) at increasing downwind distances from roadways is warranted. Fine particulate matter (PM_2.5) mass concentrations, polycyclic aromatic hydrocarbons (PAHs), hopanes, and elemental carbon (EC) concentrations generally exhibited concentrations that decreased with distance downwind of SH-71. Concentrations of organic carbon (OC) increased from upwind concentrations immediately downwind of SH-71 and continued to increase further downwind from the roadway. This behavior may have primarily resulted from condensation of semi-volatile organic species emitted from vehicle sources with transport downwind of the roadway.     

Distribution of environmentally sensitive elements in residential soils near a coal-fired power plant: Potential risks to ecology and children’s health

One hundred and twelve soil samples were collected from residential areas surrounding a coal-fired power plant at Huainan City, Anhui Province, China. The concentrations of environmentally sensitive elements (ESEs As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, V and Zn) in soil samples were determined, and their potential ecological and health risks were assessed. Mean concentrations of ESEs in the downwind soils of the power plant are relatively higher than those in the upwind soils, pointing to a potential ESEs input from coal combustion. The calculated ecological risk of ESEs in soils indicates a relatively low ecological risk. Hazard quotient (HQ) of ESEs in downwind soils is 1.5, suggesting a potential health risk for children. However, the carcinogenic risk values of ESEs in soils are within the acceptable non-hazardous range of 1E−06–1E−04.     

Infiltration of Roof Exhaust Gases into Aluminum Potrooms

Atmospheric tracer techniques were used in 21 tests to determine infiltration rates of roof exhaust gases in downwind potrooms at an aluminum reduction plant during two summer months. During each tracer test SF₆ and, in some cases, CB_rF₃ were released to simulate the exhaust gases, and tracer concentrations were measured along the ventilation doors of downwind rooms. Maximum infiltration rates were less than 5 % of the tracer release rate. The location of the maximum infiltration occurred along the upwind side of the first downwind room in two thirds of the cases and along the downwind edge of the same room where tracer was released in one third of the tests. For rooms further downwind the infiltration rate was less than 1%.