RESUMO
Coal combustion accounts for approximately two-thirds of global anthropogenic mercury (Hg) emissions. Enhanced deposition of Hg can occur close to coal-fired utility boilers (CFUBs), but it is difficult to link specific point sources with local deposition. Measurement of Hg stable isotope ratios in precipitation holds promise as a tool to assist in the identification of local Hg deposition related to anthropogenic emissions. We collected daily event precipitation samples in close proximity to a large CFUB in Crystal River, Florida. Precipitation samples collected in Crystal River were isotopically distinct and displayed large negative δ(202)Hg values (mean = -2.56, 1 SD = 1.10, n = 28). In contrast, precipitation samples collected at other sites in FL that were not greatly impacted by local coal combustion were characterized by δ(202)Hg values close to 0 (mean = 0.07, 1 SD = 0.17, n = 13). These results indicate that, depending on factors such as powdered coal isotopic composition and efficiency of Hg removal from flue gas, Hg deposited near CFUBs can be isotopically distinct. As this tool is further refined through future studies, Hg stable isotopes may eventually be used to quantify local deposition of Hg emitted by large CFUBs.
Assuntos
Carvão Mineral , Mercúrio/análise , Centrais Elétricas , Atmosfera/química , Fracionamento Químico , Precipitação Química , Florida , Isótopos de Mercúrio , Rios/química , Poluentes Químicos da Água/análiseRESUMO
BACKGROUND: Increases in ambient particulate matter of aerodynamic diameter of 2.5 µm (PM2.5) are associated with asthma morbidity and mortality. The overall objective of this study was to test the hypothesis that PM2.5 derived from two distinct urban U.S. communities would induce variable responses to aggravate airway symptoms during experimental asthma. METHODS: We used a mobile laboratory to conduct community-based inhalation exposures to laboratory rats with ovalbumin-induced allergic airways disease. In Grand Rapids exposures were conducted within 60 m of a major roadway, whereas the Detroit was located in an industrial area more than 400 m from roadways. Immediately after nasal allergen challenge, Brown Norway rats were exposed by whole body inhalation to either concentrated air particles (CAPs) or filtered air for 8 h (7:00 AM - 3:00 PM). Both ambient and concentrated PM2.5 was assessed for mass, size fractionation, and major component analyses, and trace element content. Sixteen hours after exposures, bronchoalveolar lavage fluid (BALF) and lung lobes were collected and evaluated for airway inflammatory and mucus responses. RESULTS: Similar CAPs mass concentrations were generated in Detroit (542 µg/m3) and Grand Rapids (519 µg/m3). Exposure to CAPs at either site had no effects in lungs of non-allergic rats. In contrast, asthmatic rats had 200% increases in airway mucus and had more BALF neutrophils (250% increase), eosinophils (90%), and total protein (300%) compared to controls. Exposure to Detroit CAPs enhanced all allergic inflammatory endpoints by 30-100%, whereas inhalation of Grand Rapids CAPs suppressed all allergic responses by 50%. Detroit CAPs were characterized by high sulfate, smaller sized particles and were derived from local combustion sources. Conversely Grand Rapids CAPs were derived primarily from motor vehicle sources. CONCLUSIONS: Despite inhalation exposure to the same mass concentration of urban PM2.5, disparate health effects can be elicited in the airways of sensitive populations such as asthmatics. Modulation of airway inflammatory and immune responses is therefore dependent on specific chemical components and size distributions of urban PM2.5. Our results suggest that air quality standards based on particle speciation and sources may be more relevant than particle mass to protect human health from PM exposure.
Assuntos
Poluição do Ar/efeitos adversos , Asma/etiologia , Exposição por Inalação/efeitos adversos , Material Particulado/efeitos adversos , Poluição do Ar/análise , Animais , Asma/patologia , Hiper-Reatividade Brônquica/etiologia , Hiper-Reatividade Brônquica/patologia , Líquido da Lavagem Broncoalveolar/citologia , Líquido da Lavagem Broncoalveolar/imunologia , Monitoramento Ambiental/métodos , Humanos , Exposição por Inalação/análise , Pulmão/patologia , Tamanho da Partícula , Material Particulado/análise , Ratos , Ratos Endogâmicos BN , Mucosa Respiratória/patologia , Emissões de Veículos/toxicidadeRESUMO
BACKGROUND: Increases in particulate matter less than 2.5 µm (PM(2.5)) in ambient air is linked to acute cardiovascular morbidity and mortality. Specific components and potential emission sources of PM(2.5) responsible for adverse health effects of cardiovascular function are unclear. METHODS: Spontaneously hypertensive rats were implemented with radiotelemeters to record ECG responses during inhalation exposure to concentrated ambient particles (CAPs) for 13 consecutive days in Steubenville, OH. Changes in heart rate (HR) and its variability (HRV) were compared to PM(2.5) trace elements in 30-min time frames to capture acute physiological responses with real-time fluctuations in PM(2.5) composition. Using positive matrix factorization, six major source factors were identified: (i) coal/secondary, (ii) mobile sources, (iii) metal coating/processing, (iv) iron/steel manufacturing, (v) lead and (vi) incineration. RESULTS: Exposure-related changes in HR and HRV were dependant on winds predominately from either the northeast (NE) or southwest (SW). During SW winds, the metal processing factor was associated with increased HR, whereas factors of incineration, lead and iron/steel with NE winds were associated with decreased HR. Decreased SDNN was dominated during NE winds by the incinerator factor, and with SW winds by the metal factor. Metals and mobile source factors also had minor impacts on decreased SDNN with NE winds. Individual elemental components loaded onto these factors generally showed significant associations, although there were some discrepancies. CONCLUSIONS: Acute cardiovascular changes in response to ambient PM(2.5) exposure can be attributed to specific PM constituents and sources linked with incineration, metal processing, and iron/steel production.
Assuntos
Fenômenos Fisiológicos Cardiovasculares , Hipertensão/induzido quimicamente , Material Particulado , Vento , Poluentes Atmosféricos/efeitos adversos , Animais , Exposição Ambiental , Monitoramento Ambiental , Frequência Cardíaca/efeitos dos fármacos , Incineração , Exposição por Inalação/efeitos adversos , Ferro/análise , Chumbo/análise , Masculino , Ohio , Tamanho da Partícula , Ratos , Ratos Endogâmicos SHR , Oligoelementos/análiseRESUMO
Atmospheric deposition is a primary pathway by which mercury (Hg) enters terrestrial and aquatic ecosystems; however, the chemical and meteorological processes that Hg undergoes from emission to deposition are not well understood. Hg stable isotope geochemistry is a growing field used to better understand Hg biogeochemical cycling. To examine the atmospheric Hg isotopic composition in the Great Lakes, precipitation and ambient vapor-phase Hg samples were collected in Chicago, IL, Holland, MI, and Dexter, MI, between April 2007 and September 2009. Precipitation samples were characterized by negative mass-dependent fractionation (MDF) (δ(202)Hg = -0.79 to 0.18), while most vapor-phase samples displayed positive MDF (δ(202)Hg = -0.59 to 0.43). Positive mass-independent fractionation (MIF) (Δ(199)Hg = 0.04 to 0.52) was observed in precipitation, whereas MIF was slightly negative in vapor-phase samples (Δ(199)Hg = -0.21 to 0.06). Significant positive MIF of (200)Hg up to 0.25 was also measured in precipitation. Such MIF of an even-mass Hg isotope has not been previously reported in natural samples. These results contrast with recent predictions of the isotopic composition of atmospheric Hg and suggest that, in addition to aqueous photoreduction, other atmospheric redox reactions and source-related processes may contribute to isotopic fractionation of atmospheric Hg.
Assuntos
Poluentes Atmosféricos/análise , Isótopos/análise , Mercúrio/análise , Poluentes Químicos da Água/análise , Água DoceRESUMO
Toxicological effects have been observed in rats exposed to concentrated ambient particles (CAPs) from different regions of the United States. The objective of this study was to evaluate the cardiopulmonary and systemic effects of CAPs in Detroit. The authors stationed a mobile concentrator at a location near major traffic and industrial sources. Spontaneously hypertensive (SH) and Wistar-Kyoto (WKY) rats were exposed to fine CAPs (diameter < 0.1-2.5 microm) 8 h/day for 13 consecutive days. Animals were implanted with telemeters, and electrocardiogram data were recorded continuously. Bronchoalveolar lavage (BAL) fluid and plasma were analyzed. Comprehensive exposure monitoring was conducted, including CAPs components. CAPs exposure concentrations were 103-918 microg/m(3) (mean = 502 microg/m(3)). The authors found no statistically significant differences in heart rate or SDNN (standard deviation of the normal-to-normal intervals), a measure of heart rate variability, between CAPs-exposed and control rats. The authors found significantly higher levels of C-reactive protein in the serum of CAPs-exposed SH rats compared with air-exposed animals. Protein in BAL fluid was elevated in WKY rats exposed to CAPs. Measurement of trace metals in lung tissue showed elevated concentrations of V, Sb, La, and Ce in CAPs-exposed SH animals versus controls. These elements are generally associated with oil combustion, oil refining, waste incineration, and traffic. Examination of wind rose data from the exposure period confirmed that the predominant wind direction was SSW, the direction of many of the aforementioned sources. These results indicate that ambient particles in Detroit can cause mild pulmonary and systemic changes in rats, and suggest the importance of local PM(2.5) sources in these effects.
Assuntos
Poluentes Atmosféricos/toxicidade , Frequência Cardíaca/efeitos dos fármacos , Hipertensão/fisiopatologia , Pulmão/efeitos dos fármacos , Material Particulado/toxicidade , Poluentes Atmosféricos/análise , Poluentes Atmosféricos/farmacocinética , Animais , Líquido da Lavagem Broncoalveolar/citologia , Proteína C-Reativa/análise , Eletrocardiografia , Monitoramento Ambiental/métodos , Hipertensão/metabolismo , Hipertensão/patologia , Pulmão/metabolismo , Pulmão/patologia , Masculino , Material Particulado/análise , Material Particulado/farmacocinética , Ratos , Ratos Endogâmicos SHR , Ratos Endogâmicos WKY , Oligoelementos/metabolismo , Troponina I/sangueRESUMO
Increased concentrations of airborne fine particulate matter (PM2.5; particulate matter with an aerodynamic diameter < or = 2.5 microm) are associated with increases in emergency room visits and hospitalizations of asthmatic patients. Emissions from local stationary combustion sources (e.g., coal-burning power plants) or mobile motor vehicles (e.g., diesel-powered trucks) have been identified as potential contributors to the development or exacerbation of allergic airway disease. In the present study, a rodent model of allergic airway disease was used to study the effects of concentrated ambient particles (CAPs) or diesel engine exhaust (DEE) on the development of allergic airway disease in rats sensitized to the allergen ovalbumin (OVA). The overall objective of our project was to understand the effects of PM2.5 on the development of OVA-induced allergic airway disease. Our specific aims were to test the following hypotheses: (1) exposure to CAPs during OVA challenge enhances epithelial remodeling of the airway and inflammation in rats previously sensitized to the allergen; and (2) exposure to DEE during OVA sensitization, or during OVA challenge, exacerbates epithelial remodeling of the airway and inflammation in rats. In the DEE studies, Brown Norway (BN) rats were sensitized with three daily intranasal (IN) instillations of 0.5% OVA, and then two weeks later were challenged with IN OVA or saline for 3 consecutive days. Rats were exposed to DEE diluted to mass concentrations of 30 or 300 microg/m3 diesel exhaust particles (DEPs) or to filtered air during either the sensitization or challenge periods. For the CAPs studies, the same OVA sensitization and challenge rat model was used but exposures to Detroit, Michigan, CAPs were limited to the OVA challenge period. Two separate 3-day CAPs exposures were conducted (week 1, high mean mass concentration = 595 microg/m3; week 2, low mean mass concentration = 356 microg/m3) during OVA challenge. In both the DEE and CAPs studies, rats were killed 24 hours after the last OVA challenge, bronchoalveolar lavage fluid (BALF) was collected and analyzed for cellularity and secreted mediators, and lungs and nose were processed for histopathologic examination and morphometric analysis of intraepithelial mucosubstances (IM). The results of our animal inhalation studies in the southwest (SW) Detroit community, an area with elevated ambient PM2.5 concentrations, suggested that, during allergen challenge, exposure to CAPs that were predominantly associated with emissions from combustion sources markedly enhanced the OVA-induced allergic airway disease, which was characterized by an increased infiltration in the lungs of eosinophilic and lymphocytic inflammation, increased IM in conducting airways, and increased concentrations in BALF of mucin-specific proteins and inflammatory cytokines. These findings suggest that urban airborne PM2.5 derived from stationary combustion sources (e.g., refineries, coal-burning power plants, waste-treatment plants) may enhance the development of human allergic airway diseases like childhood asthma. Previous animal inhalation studies in this community have also suggested that these fine, ambient combustion-derived particles may also exacerbate preexisting allergic airway disease. In contrast to our CAPs studies in Detroit, the controlled DEE exposures of allergen-sensitized BN rats, during either allergen sensitization or challenge periods, caused only a few mild modifications in the character of the allergen-induced disease. This finding contrasts with other reported studies that indicate that DEPs at relatively higher exposure doses do enhance allergic airway disease in some rodent models. The reasons for these disparities between studies likely reflect differences in exposure dose, animal models, the timing of exposures to the allergens and DEP exposures, the methods of allergen sensitization and challenge, or physicochemical differences among DEEs.
Assuntos
Alérgenos , Hiper-Reatividade Brônquica/etiologia , Material Particulado/efeitos adversos , Emissões de Veículos/toxicidade , Poluentes Atmosféricos/efeitos adversos , Poluentes Atmosféricos/análise , Animais , Asma , Hiper-Reatividade Brônquica/diagnóstico , Hiper-Reatividade Brônquica/patologia , Masculino , Material Particulado/análise , RatosRESUMO
Recent investigations indicate that wildfires provide a significant flux of mercury (Hg) from terrestrial ecosystems to the atmosphere. However, little is known about how geographic location, climate, stand age, and tree species affect Hg accumulation prior to burning and loss during burning. Soil cores collected in sites burned during the summer 2001 Rex Creek Fire in the eastern Cascade Mountains (Washington State, USA) and in adjacent unburned control sites indicate that Hg loss from soils during the Rex Creek Fire averaged 6.7 (+/-2.5) g Hg ha(-1). This soil profile-based estimate of Hg release is higher than a previous estimate for the same fire based on airborne measurements of Hg and CO concentrations in smoke. This study has implications for global estimates of Hg storage in forests and release to the atmosphere during wildfires.
Assuntos
Compostos de Mercúrio/análise , Poluentes do Solo/análise , Árvores , Clima , Ecossistema , Monitoramento Ambiental/estatística & dados numéricos , Incêndios , Solo/análise , WashingtonRESUMO
In a longitudinal cohort study of primary-school-age children with asthma in Detroit, Michigan, we examined relationships between lung function and ambient levels of particulate matter < or = 10 microm and < or = 2.5 microm in diameter (PM10 and PM2.5) and ozone at varying lag intervals using generalized estimating equations. Models considered effect modification by maintenance corticosteroid (CS) use and by the presence of an upper respiratory infection (URI) as recorded in a daily diary among 86 children who participated in six 2-week seasonal assessments from winter 2001 through spring 2002. Participants were predominantly African American from families with low income, and > 75% were categorized as having persistent asthma. In both single-pollutant and two-pollutant models, many regressions demonstrated associations between higher exposure to ambient pollutants and poorer lung function (increased diurnal variability and decreased lowest daily values for forced expiratory volume in 1 sec) among children using CSs but not among those not using CSs, and among children reporting URI symptoms but not among those who did not report URIs. Our findings suggest that levels of air pollutants in Detroit, which are above the current National Ambient Air Quality Standards, adversely affect lung function of susceptible asthmatic children.
Assuntos
Poluentes Atmosféricos/efeitos adversos , Poluição do Ar/efeitos adversos , Asma/fisiopatologia , Ozônio/efeitos adversos , Corticosteroides/uso terapêutico , Poluentes Atmosféricos/análise , Poluição do Ar/análise , Asma/complicações , Asma/tratamento farmacológico , Criança , Poeira/análise , Monitoramento Ambiental , Monitoramento Epidemiológico , Feminino , Volume Expiratório Forçado , Humanos , Masculino , Michigan/epidemiologia , Modelos Biológicos , Ozônio/análise , Tamanho da Partícula , Pico do Fluxo Expiratório , Infecções Respiratórias/complicações , População UrbanaRESUMO
A real-world assessment of the source-to-receptor pathways for ambient particulate matter (PM), as opposed to in a laboratory environment, was crucial for gaining a better understanding of the types of particles to which people are actually exposed in their daily lives, and of the human-health risks for source-specific PM. However, obtaining scientific evidence linking specific source emissions to health responses was not an easy task; ambient PM possesses diverse chemical, physical and thermodynamic properties, and is subjected to numerous complex atmospheric processes in which source type, source strength, sinks, and meteorology interact continuously. Our collaborative PM health research studies utilized an integrated approach that employs detailed characterization of ambient PM concurrent with inhalation toxicology studies using animal models and concentrated fine air particulates (CAPs). Ambient PM2.5 (PM less than 2.5 microm in mean aerodynamic diameter) was concentrated with a Harvard fine particle concentrator housed in AirCARE1, a unique mobile air research laboratory which enables inhalation exposure studies in real-world settings. This paper discusses the importance of comprehensive characterization of ambient PM2.5, CAPs and their sources, and the associated challenges. In a southwest Detroit community where the pediatric asthma rate is about three times the national average, a detailed assessment was performed including: characterization of ambient PM2.5 and CAPs; identification of major emission sources of PM2.5; and quantification of trace elements in lung tissues of laboratory rats that were exposed to CAPs, all in an effort to define source-receptor pathways for ambient PM2.5. Our findings to date constitute evidence of the retention of ambient urban particulates from local combustion sources within animal tissues from short-term exposures, and possible associations between the observed health effects and source-specific PM2.5. However, a complete understanding of the effects of complex mixtures of air pollutants and their toxicological impacts still faces many challenges.
Assuntos
Poluentes Atmosféricos/química , Misturas Complexas/química , Exposição Ambiental/análise , Exposição por Inalação/análise , Saúde da População Urbana , Poluentes Atmosféricos/farmacocinética , Animais , Asma/epidemiologia , Asma/etiologia , Misturas Complexas/farmacocinética , Monitoramento Ambiental , Monitoramento Epidemiológico , Humanos , Exposição por Inalação/efeitos adversos , Pulmão/química , Pulmão/efeitos dos fármacos , Pulmão/metabolismo , Michigan/epidemiologia , Tamanho da Partícula , Ratos , Oligoelementos/análiseRESUMO
We report on the research conducted by the Community Action Against Asthma (CAAA) in Detroit, Michigan, to evaluate personal and community-level exposures to particulate matter (PM) among children with asthma living in an urban environment. CAAA is a community-based participatory research collaboration among academia, health agencies, and community-based organizations. CAAA investigates the effects of environmental exposures on the residents of Detroit through a participatory process that engages participants from the affected communities in all aspects of the design and conduct of the research; disseminates the results to all parties involved; and uses the research results to design, in collaboration with all partners, interventions to reduce the identified environmental exposures. The CAAA PM exposure assessment includes four seasonal measurement campaigns each year that are conducted for a 2-week duration each season. In each seasonal measurement period, daily ambient measurements of PM2.5 and PM10 (particulate matter with a mass median aerodynamic diameter less than 2.5 microm and 10 microm, respectively) are collected at two elementary schools in the eastside and southwest communities of Detroit. Concurrently, indoor measurements of PM2.5 and PM10 are made at the schools as well as inside the homes of a subset of 20 children with asthma. Daily personal exposure measurements of PM10 are also collected for these 20 children with asthma. Results from the first five seasonal assessment periods reveal that mean personal PM10 (68.4 39.2 microg/m(3)) and indoor home PM10 (52.2 30.6 microg/m(3)) exposures are significantly greater (p < 0.05) than the outdoor PM10 concentrations (25.8 11.8 microg/m(3)). The same was also found for PM2.5 (indoor PM2.5 = 34.4 21.7 microg/m(3); outdoor PM2.5 = 15.6 8.2 microg/m(3)). In addition, significant differences (p < 0.05) in community-level exposure to both PM10 and PM2.5 are observed between the two Detroit communities (southwest PM10 = 28.9 14.4 microg/m(3)), PM2.5 = 17.0 9.3 microg/m(3); eastside PM10 = 23.8 12.1 microg/m(3), PM2.5 = 15.5 9.0 microg/m(3). The increased levels in the southwest Detroit community are likely due to the proximity to heavy industrial pollutant point sources and interstate motorways. Trace element characterization of filter samples collected over the 2-year period will allow a more complete assessment of the PM components. When combined with other project measures, including concurrent seasonal twice-daily peak expiratory flow and forced expiratory volume at 1 sec and daily asthma symptom and medication dairies for 300 children with asthma living in the two Detroit communities, these data will allow not only investigations into the sources of PM in the Detroit airshed with regard to PM exposure assessment but also the role of air pollutants in exacerbation of childhood asthma.
Assuntos
Poluentes Atmosféricos/efeitos adversos , Asma/etiologia , Proteção da Criança , Exposição Ambiental , Adolescente , Poluentes Atmosféricos/análise , Criança , Pré-Escolar , Cidades , Monitoramento Ambiental , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Michigan , Tamanho da Partícula , Testes de Função Respiratória , Estações do Ano , População UrbanaRESUMO
This paper presents results from a study conducted in southwest Detroit from July 20 to July 30, 2002, to characterize ambient ultrafine particles (dP < 0.1 microm), and to examine the effect of local sources and meteorological parameters on the ultrafine number concentration and size distribution. The number concentrations of ambient particles in the size range of 0.01-0.43 microm were obtained from a scanning mobility particle sizer (SMPS). Meteorological parameters including ambient temperature, relative humidity, wind speed, wind direction, rainfall, and solar radiation flux were also monitored concurrently atop a 10-m tower. On average, ultrafine particles ranged from 1.4 x 10(4) to 2.5 x 10(4) cm(-3), with significant diurnal and daily variations, and accounted for approximately 89% of the total number concentration (0.01 < dP < 0.43 microm). Time-series plots of the 5-min number concentrations revealed that peak concentrations often occurred during morning rush hour and/or around solar noon when photochemical activity was at a maximum. The morning traffic-related peak coincided with the NOx peak, whereas the photochemical-related peak correlated with solar radiation flux. On some days, the noon peak concentration was many times higher than the morning peak concentration. Although the number size distribution varied considerably over the course of the study, it typically exhibited one to three modes, with diameters around 0.01, 0.05, and 0.09 microm. Analysis of the influence of wind direction indicated that stationary sources could be one of the contributors to elevated ultrafine particle concentration. Overall, the data indicated that fossil fuel combustion and atmospheric gas-to-particle conversion of precursor gases are the major sources of ultrafine particles in the southwest Detroit area during the summer.
Assuntos
Poluentes Atmosféricos/análise , Cidades , Conceitos Meteorológicos , Michigan , Tamanho da Partícula , Estações do Ano , Fatores de TempoRESUMO
From August 4, 2007 to August 31, 2009, we collected event-based precipitation samples for mercury (Hg) and trace element analyses at four sites in Illinois (IL), USA. The objectives of these measurements were to quantify Hg wet deposition across the state, and to assess the contributions to Hg in precipitation from major local and regional emission sources. Monitoring sites were located, from north to south, in Chicago, Peoria, Nilwood, and Carbondale, IL. Measurements from these four sites demonstrated that a clear spatial gradient in Hg wet deposition was not evident across the state. Each site received>10µgm(-2) of Hg wet deposition annually, and these observed values were comparable to annual Hg wet deposition measurements from other event-based precipitation monitoring sites in source-impacted areas of the Midwestern U.S. We applied the multivariate statistical receptor model, Positive Matrix Factorization (EPA PMF v3.0), to the measured Hg and trace element wet deposition amounts at the four sites. Results suggested that 50% to 74% of total Hg wet deposition at each site could be attributed to coal combustion emissions. The other source signatures identified in the precipitation compositions included cement manufacturing, mixed metal smelting/waste incineration, iron-steel production, and a phosphorus source. We also applied a hybrid receptor model, Quantitative Transport Bias Analysis (QTBA), to the Hg wet deposition datasets to identify the major source regions associated with the measured values. The calculated QTBA probability fields suggested that transport from urban/industrial areas, such as Chicago/Gary, St. Louis, and the Ohio River Valley, resulted in some of the highest estimated event-based Hg wet deposition amounts at the four sites (potential mass transfer of up to 0.32µgm(-2)). The combined application of PMF and QTBA supported the hypothesis that local and regional coal combustion was the largest source of Hg wet deposition in Illinois.
Assuntos
Poluentes Atmosféricos/química , Atmosfera/química , Monitoramento Ambiental , Mercúrio/química , Movimentos do Ar , Poluentes Atmosféricos/análise , Carvão Mineral , Materiais de Construção , Resíduos Perigosos , Illinois , Incineração , Indústrias , Ferro , Mercúrio/análise , Análise Multivariada , Chuva/química , Esgotos , AçoRESUMO
Intra-storm variability and soluble fractionation was explored for summer-time rain events in Steubenville, Ohio to evaluate the physical processes controlling mercury (Hg) in wet deposition in this industrialized region. Comprehensive precipitation sample collection was conducted from July through September 2006 using three different methods to evaluate both soluble and insoluble fractions as well as scavenging and washout properties of Hg and a suite of trace elements. Real-time filtration of event total precipitation revealed that 61±17% (mean±standard deviation) of Hg in wet deposition was in a soluble form. Comparison of total and dissolved element concentrations (solubility fractionation) showed the following order of decreasing solubility: S>Na>Se>Ca>Mg>Hg>As>Mn>V>Cr>Fe>La≈Ce ranging from 95% (S) to 4% (Ce). To examine removal mechanisms occurring during the course of a precipitation event, discrete, sequential sub-event precipitation samples were collected. Results indicated that Hg had lower "scavenging coefficients" (the rate of Hg concentration decrease throughout the events) than the majority of elements analyzed, indicating that either (i) Hg is incorporated into rain via gas phase inclusion or particulate nucleation within cloud, or (ii) Hg is available in the boundary layer for scavenging, even in the latter stages of precipitation. The Hg scavenging coefficient (-0.39) was low compared to S (-0.73), a co-pollutant of Hg. When compared to an upwind, regionally representative site, the scavenging coefficient of Hg for the locally influenced precipitation was 25% lower. This observation suggests that a continuous feed of soluble Hg was the reason for the low scavenging coefficient. Overall, this investigation of Hg wet deposition in Steubenville indicates that the physical and chemical properties of Hg emissions are driving the elevated deposition rates observed near point sources.
Assuntos
Monitoramento Ambiental/métodos , Poluentes Ambientais/análise , Mercúrio/análise , Chuva/química , Neve/química , Movimentos do Ar , Atmosfera/química , Poluentes Ambientais/química , Mercúrio/química , Ohio , RiosRESUMO
Quantifying the local and regional impacts of speciated mercury (Hg) emissions from major urban and industrial areas is critical for understanding Hg transport and cycling in the environment. The Chicago/Gary urban area is one location where Hg emissions from industrial sources are significant and the regional transport of emissions may contribute to elevated ambient Hg concentrations at downwind locations. From July to November 2007, we collected semi-continuous measurements of gaseous elemental Hg (Hg(0)), fine particulate bound Hg (Hgp), and divalent reactive gaseous Hg (RGM) in Chicago, IL and Holland, MI to characterize the impact of Chicago/Gary source emissions on Hg concentrations in southwest Michigan and to improve our overall understanding of speciated Hg transport and deposition. The mean (and median) concentrations of Hg(0), Hgp, and RGM in Chicago were 2.5ng/m(3) (1.9ng/m(3)), 9pg/m(3) (5pg/m(3)), and 17pg/m(3) (6pg/m(3)), respectively. In Holland the mean (and median) concentrations were 1.3ng/m(3) (1.3ng/m(3)), 6pg/m(3) (6pg/m(3)), and 8pg/m(3) (2pg/m(3)), respectively. Cluster analysis of 24-hour HYSPLIT back-trajectories associated with the semi-continuous Hg measurements indicated that southwest transport from Chicago/Gary to Holland occurred during approximately 27% of the study. In Holland, under this transport regime, we observed a five-fold increase in RGM relative to the median concentration of the other transport clusters. We applied the HYSPLIT dispersion model to two case study periods to further quantify the impact of Chicago/Gary sources on southeast Michigan and investigate the role of direct transport and dispersion of speciated Hg emissions. Results suggested that more than 50% of the maximum RGM concentrations observed in Holland during the selected periods could be attributed to direct transport of primary RGM emissions from Chicago/Gary. The remaining RGM fractions are believed to be associated with Hg(0) oxidation during transport over Lake Michigan.
Assuntos
Movimentos do Ar , Poluentes Atmosféricos/análise , Atmosfera/química , Monitoramento Ambiental , Mercúrio/análise , Poluentes Atmosféricos/química , Chicago/epidemiologia , Análise por Conglomerados , Geografia , Illinois , Lagos/química , Mercúrio/química , Michigan , OxirreduçãoRESUMO
RATIONALE: Information on how ambient air pollution affects susceptible populations is needed to ensure protective air quality standards. OBJECTIVES: To estimate the effect of community-level ambient particulate matter (PM) and ozone (O) on respiratory symptoms among primarily African-American and Latino, lower-income asthmatic children living in Detroit, Michigan and to evaluate factors associated with heterogeneity in observed health effects. METHODS: A cohort of 298 children with asthma was studied prospectively from 1999 to 2002. For 14days each season over 11 seasons, children completed a respiratory symptom diary. Simultaneously, ambient pollutant concentrations were measured at two community-level monitoring sites. Logistic regression models using generalized estimating equations were fit for each respiratory symptom in single pollutant models, looking for interactions by area or by corticosteroid use, a marker of more severe asthma. Exposures of interest were: daily concentrations of PM<10µm, <2.5µm, and between 10 and 2.5µm in aerodynamic diameter (PM, PM, and PM respectively), the daily 8-hour maximum concentration of O (8HrPeak), and the daily 1-hour maximum concentration of O (1HrPeak). RESULTS: Outdoor PM, PM, 8HrPeak, and 1HrPeak O concentrations were associated with increased odds of respiratory symptoms, particularly among children using corticosteroid medication and among children living in the southwest community of Detroit. Similar patterns of associations were not seen with PM. CONCLUSIONS: PM and O at levels near or below annual standard levels are associated with negative health impact in this population of asthmatic children. Variation in effects within the city of Detroit and among the subgroup using steroids emphasizes the importance of spatially refined exposure assessment and the need for further studies to elucidate mechanisms and effective risk reduction interventions.
Assuntos
Corticosteroides/uso terapêutico , Poluição do Ar/análise , Asma/complicações , Monitoramento Ambiental , Material Particulado/toxicidade , Asma/tratamento farmacológico , Asma/epidemiologia , Criança , Estudos de Coortes , Feminino , Humanos , Modelos Logísticos , Masculino , Michigan/epidemiologia , Tamanho da Partícula , Material Particulado/análise , Fatores SocioeconômicosRESUMO
BACKGROUND: Exposure to fine particulate matter [aerodynamic diameter ≤ 2.5 µm (PM2.5)] is linked to adverse cardiopulmonary health effects; however, the responsible constituents are not well defined. OBJECTIVE: We used a rat model to investigate linkages between cardiac effects of concentrated ambient particle (CAP) constituents and source factors using a unique, highly time-resolved data set. METHODS: Spontaneously hypertensive rats inhaled Detroit Michigan, CAPs during summer or winter (2005-2006) for 13 consecutive days. Electrocardiogram data were recorded continuously, and heart rate (HR) and heart rate variability (HRV) metrics were derived. Extensive CAP characterization, including use of a Semicontinuous Elements in Aerosol Sampler (SEAS), was performed, and positive matrix factorization was applied to investigate source factors. RESULTS: Mean CAP exposure concentrations were 518 µg/m(3) and 357 µg/m(3) in the summer and winter, respectively. Significant reductions in the standard deviation of the normal-to-normal intervals (SDNN) in the summer were strongly associated with cement/lime, iron/steel, and gasoline/diesel factors, whereas associations with the sludge factor and components were less consistent. In winter, increases in HR were associated with a refinery factor and its components. CAP-associated HR decreases in winter were linked to sludge incineration, cement/lime, and coal/secondary sulfate factors and most of their associated components. Specific relationships for increased root mean square of the standard deviation of successive normal-to-normal intervals (RMSSD) in winter were difficult to determine because of lack of consistency between factors and associated constituents. CONCLUSIONS: Our results indicate that specific modulation of cardiac function in Detroit was most strongly linked to local industrial sources. Findings also highlight the need to consider both factor analytical results and component-specific results when interpreting findings.
Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental/métodos , Frequência Cardíaca/efeitos dos fármacos , Hipertensão/fisiopatologia , Material Particulado/análise , Poluentes Atmosféricos/toxicidade , Animais , Relação Dose-Resposta a Droga , Masculino , Michigan , Material Particulado/toxicidade , RatosRESUMO
Extensive exploration of event precipitation data in the Ohio River Valley indicates that coal combustion emissions play an important role in mercury (Hg) wet deposition. During July-September 2006, an intensive study was undertaken to discern the degree of local source influence. Source-receptor relationships were explored by establishing a set of wet deposition sites in and around Steubenville, Ohio. For the three month period of study, volume-weighted mean Hg concentrations observed at the eight sites ranged from 10.2 to 223 ng L(-1), but this range increased drastically on an event basis with a maximum concentration of 89.4 ng L(-1) and a minimum concentration of 4.1 ng L(-1). A subset of events was explored in depth, andthe degree of variability in Hg concentrations between sites was linked to the degree of local source enhancement. Samples collected at sites less than 1 km from coal-fired utility stacks (near-field) exhibited up to 72% enhancement in Hg concentrations over regionally representative samples on an event basis. Air mass transport and precipitating cell histories were traced in order to evaluate relationships between local point sources and receptor sites. It was found that the interaction of several dynamic atmospheric parameters combined to favor local Hg concentration enhancement over the more regional contribution. When significant meteorological factors (wind speed at time of maximum rain rate, wind speed 24 h prior to precipitation, mixing height, and observed ceiling) were explored, it was estimated that during summertime precipitation, 42% of Hg concentration in near-field samples could be attributed to the adjacent coal-fired utility source.
Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental/métodos , Mercúrio/análise , Chuva , Carvão Mineral/análise , Incineração , Metalurgia , Modelos Teóricos , Ohio , Petróleo , Centrais Elétricas , Estações do AnoRESUMO
Recent studies have suggested a link between exposure to ambient particulate matter <2.5 microm in diameter (PM(2.5)) and adverse cardiovascular outcomes. The objective of this study was to examine the effects of differing community-level exposure to PM(2.5) on daily measures of blood pressure (BP) among an adult population. During the period May 2002 through April 2003, BP was examined at 2 time points for 347 adults residing in 3 distinct communities of Detroit, Michigan. Exposure to PM(2.5) was assessed in each community during this period, along with multivariate associations between PM(2.5) and BP. In models combining all 3 of the communities, PM(2.5) was significantly associated with systolic blood pressure; a 10-microg/m(3) increase in daily PM(2.5) was associated with a 3.2-mm Hg increase in systolic blood pressure (P=0.05). However, in models that added a location interaction, larger effects were observed for systolic blood pressure within the community with highest PM(2.5) levels; a 10-microg/m(3) increase in daily PM(2.5) was associated with a 8.6-mm Hg increase in systolic blood pressure (P=0.01). We also found young age (<55 years) and not taking BP medications to be significant predictors of increased BP effects. Among those taking BP medications, the PM(2.5) effect on BP appeared to be mitigated, partially explaining the age effect, because those participants <55 years of age were less likely to take BP medications. Short-term increases in exposure to ambient PM(2.5) are associated with acute increases in BP in adults, especially within communities with elevated levels of exposure.
Assuntos
Pressão Sanguínea/efeitos dos fármacos , Material Particulado/efeitos adversos , Adulto , Fatores Etários , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Saúde da População UrbanaRESUMO
The interaction between air particulates and genetic susceptibility has been implicated in the pathogenesis of asthma. The overall objective of this study was to determine the effects of inhalation exposure to environmentally relevant concentrated air particulates (CAPs) on the lungs of ovalbumin (ova) sensitized and challenged Brown Norway rats. Changes in gene expression were compared with lung tissue histopathology, morphometry, and biochemical and cellular parameters in bronchoalveolar lavage fluid (BALF). Ova challenge was responsible for the preponderance of gene expression changes, related largely to inflammation. CAPs exposure alone resulted in no significant gene expression changes, but CAPs and ova-exposed rodents exhibited an enhanced effect relative to ova alone with differentially expressed genes primarily related to inflammation and airway remodeling. Gene expression data was consistent with the biochemical and cellular analyses of the BALF, the pulmonary pathology, and morphometric changes when comparing the CAPs-ova group to the air-saline or CAPs-saline group. However, the gene expression data were more sensitive than the BALF cell type and number for assessing the effects of CAPs and ova versus the ova challenge alone. In addition, the gene expression results provided some additional insight into the TGF-beta-mediated molecular processes underlying these changes. The broad-based histopathology and functional genomic analyses demonstrate that exposure to CAPs exacerbates rodents with allergic inflammation induced by an allergen and suggests that asthmatics may be at increased risk for air pollution effects.
Assuntos
Poluentes Atmosféricos/toxicidade , Alérgenos/administração & dosagem , Expressão Gênica/efeitos dos fármacos , Pulmão/metabolismo , Ovalbumina/administração & dosagem , Material Particulado/toxicidade , Alérgenos/imunologia , Análise de Variância , Animais , Líquido da Lavagem Broncoalveolar/química , Líquido da Lavagem Broncoalveolar/imunologia , Broncopneumonia/metabolismo , Broncopneumonia/patologia , Inflamação/imunologia , Pulmão/efeitos dos fármacos , Pulmão/imunologia , Pulmão/patologia , Masculino , Análise de Sequência com Séries de Oligonucleotídeos , Ovalbumina/imunologia , Material Particulado/administração & dosagem , Análise de Componente Principal , Ratos , Hipersensibilidade Respiratória/metabolismo , Hipersensibilidade Respiratória/patologia , Mucosa Respiratória/efeitos dos fármacos , Mucosa Respiratória/imunologia , Mucosa Respiratória/metabolismo , Mucosa Respiratória/patologiaRESUMO
There is a need to distinguish among sources of Hg to the atmosphere in order to more fully understand global Hg pollution. In this study we investigate whether coal deposits within the United States, China, and Russia-Kazakhstan, which are three of the five greatest coal-producing regions, have diagnostic Hg isotopic fingerprints that can be used to discriminate among Hg sources. We also investigate the Hg isotopic composition of modern organic soil horizons developed in areas distant from point sources of Hg in North America. Mercury stored in coal deposits displays a wide range of both mass dependent fractionation (MDF, delta202Hg) and mass independent fractionation (MIF, delta201Hg). delta202Hg varies in coals by 3 per thousand and delta201Hg varies by 0.9 per thousand. Combining these two Hg isotope signals results in what may be a unique isotopic "fingerprint" for many coal deposits. Mass independent fractionation of mercury has been demonstrated to occur during photochemical reactions of mercury. This suggests that Hg found in most coal deposits was subjected to photochemical reduction near the Earth's surface prior to deposition. The similarity in MDF and MIF of modern organic soils and coals from North America suggests that Hg deposition from coal may have imprinted an isotopic signature on soils. This research offers a new tool for characterizing mercury inputs from natural and anthropogenic sources to the atmosphere and provides new insights into the geochemistry of mercury in coal and soils.