Investigation of mercury wet deposition physicochemistry in the Ohio River Valley through automated sequential sampling.

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.

Air pollution and respiratory symptoms among children with asthma: vulnerability by corticosteroid use and residence area.

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.

Assessing the emission sources of atmospheric mercury in wet deposition across Illinois.

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.

Atmospheric transport of speciated mercury across southern Lake Michigan: Influence from emission sources in the Chicago/Gary urban area.

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.

Divergent effects of urban particulate air pollution on allergic airway responses in experimental asthma: a comparison of field exposure studies.

Background: Increases in ambient particulate matter of aerodynamic diameter of 2.5 μm (PM2.5) are associated with asthma morbidity and mortality.

Investigation of local mercury deposition from a coal-fired power plant using mercury isotopes.

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.

PM2.5-induced changes in cardiac function of hypertensive rats depend on wind direction and specific sources in Steubenville, Ohio.

Background: Increases in particulate matter less than 2.5 µm (PM(2.5)) in ambient air is linked to acute cardiovascular morbidity and mortality.

Altered heart rate variability in spontaneously hypertensive rats is associated with specific particulate matter components in Detroit, Michigan.

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.

Isotopic composition and fractionation of mercury in Great Lakes precipitation and ambient air.

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.

Cardiopulmonary responses in spontaneously hypertensive and Wistar-Kyoto rats exposed to concentrated ambient particles from Detroit, Michigan.

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.

Effects of concentrated ambient particles and diesel engine exhaust on allergic airway disease in Brown Norway rats.

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.

Spatial variability of mercury wet deposition in eastern Ohio: summertime meteorological case study analysis of local source influences.

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.

Acute effects of ambient particulate matter on blood pressure: differential effects across urban communities.

Recent studies have suggested a link between exposure to ambient particulate matter <2.5 microm in diameter (PM(2.5)) and adverse cardiovascular outcomes.

Comparative microarray analysis and pulmonary changes in Brown Norway rats exposed to ovalbumin and concentrated air particulates.

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).

Mercury storage in surface soils in a central Washington forest and estimated release during the 2001 Rex Creek Fire.

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.

Influence of snow and ice crystal formation and accumulation on mercury deposition to the Arctic.

Mercury is deposited to the Polar Regions during springtime atmospheric mercury depletion events (AMDEs) but the relationship between snow and ice crystal formation and mercury deposition is not well understood. The objective of this investigation was to determine if mercury concentrations were related to the type and formation of snow and ice crystals. On the basis of almost three hundred analyses of samples collected in the Alaskan Arctic, we suggestthat kinetic crystals growing from the vapor phase, including surface hoar, frost flowers, and diamond dust, yield mercury concentrations that are typically 2-10 times higher than that reported for snow deposited during AMDEs (approximately 80 ng/L).

Characterization of urban atmospheres during inhalation exposure studies in Detroit and Grand Rapids, Michigan.

An inhalation exposure study for particulate matter (PM) investigates links between exposure and observed changes in respiratory function by evaluating the interactions of chemical and physical properties of the PM with physiological mechanisms. Laboratory studies are useful in this regard, but provide limited information because of the difficulty in reproducing real atmospheric PM compositions and processes. To better understand the types of particles to which people are actually exposed in their daily lives, and the human health risks for source-specific PM, a real world assessment of the source-to-receptor pathways for ambient PM is vital.

Sources of mercury wet deposition in Eastern Ohio, USA.

In the fall of 2002, an enhanced air monitoring site was established in Steubenville, Ohio as part of a multi-year comprehensive mercury monitoring and source apportionment study to investigate the impact of local and regional coal combustion sources on atmospheric mercury deposition in the Ohio River Valley. This study deployed advanced monitoring instrumentation, utilized innovative analytical techniques, and applied state-of-the-art statistical receptor models. This paper presents wet deposition data and source apportionment modeling results from daily event precipitation samples collected during the calendar years 2003-2004.

Mass balance assessment for mercury in Lake Champlain.

A mass balance model for mercury in Lake Champlain was developed in an effort to understand the sources, inventories, concentrations, and effects of mercury (Hg) contamination in the lake ecosystem. To construct the mass balance model, air, water, and sediment were sampled as a part of this project and other research/monitoring projects in the Lake Champlain Basin. This project produced a STELLA-based computer model and quantitative apportionments of the principal input and output pathways of Hg for each of 13 segments in the lake.

Automated speciated mercury measurements in Michigan.

Automated speciated mercury measurements were made at a rural (Dexter, MI) and an urban (Detroit, MI) site in Michigan during selected times from 1999 to 2002 to assess the concentrations of elemental (Hg0), reactive gaseous (RGM), and particulate mercury (Hgp) in these environments. Here we present the first-ever reported values for RGM in Michigan. Median RGM concentrations were 2.

Characterization of complex mixtures in urban atmospheres for inhalation exposure studies.

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).

Air pollution-associated changes in lung function among asthmatic children in Detroit.

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.

Long-term atmospheric mercury wet deposition at Underhill, Vermont.

Section 112(m) of the 1990 Clean Air Act Amendments, referred to as the Great Waters Program, mandated an assessment of atmospheric deposition of hazardous air pollutants (HAPs) to Lake Champlain. Mercury (Hg) was listed as a priority HAP and has continued to be a high priority for a number of national and international programs. An assessment of the magnitude and seasonal variation of atmospheric Hg levels and deposition in the Lake Champlain basin was initiated in December 1992 which included event precipitation collection, as well as collection of vapor and particle phase Hg in ambient air.