Determination of Levoglucosan in Atmospheric Fine Particulate Matter

Abstract

A microanalytical method suitable for the quantitative determination of the sugar anhydride levoglucosan in low-volume samples of atmospheric fine particulate matter (PM) has been developed and validated. The method incorporates two sugar anhydrides as quality control standards. The recovery standard sedoheptulosan (2,7-anhydro-β-D-altro-heptulopyranose) in 20 μL solvent is added onto samples of the atmospheric fine PM and aged for 1 hr before ultrasonic extraction with ethylacetate/ triethylamine. The extract is reduced in volume, an internal standard is added (1,5-anhydro-D-mannitol), and a portion of the extract is derivatized with 10% by volume N-trimethylsilylimidazole. The derivatized extract is analyzed by gas chromatography/mass spectrometry (GC/MS). The recovery of levoglucosan using this procedure was 69 ± 6% from five filters amended with 2 μg levoglu-cosan, and the reproducibility of the assay is 9%. The limit of detection is ～0.1 μg/mL, which is equivalent to ～3.5 ng/m³ for a 10 L/min sampler or ～8.7 ng/m³ for a 4 L/min personal sampler (assuming 24-hr integrated samples). We demonstrated that levoglucosan concentrations in collocated samples (expressed as ng/m³) were identical irrespective of whether samples were collected by PM with aerodynamic diameter ≤2.5 μm or PM with aerodynamic diameter ≤10 μm impactors. It was also demonstrated that X-ray fluorescence analysis of samples of atmospheric PM, before levoglucosan determinations, did not alter the levels of levoglucosan.     

The Southeastern Aerosol Research and Characterization Study: Part 1—Overview

Abstract

This paper presents an overview of a major, long-term program for tropospheric gas and aerosol research in the southeastern United States. Building on three existing ozone (O₃)-focused research sites begun in mid-1992, the Southeastern Aerosol Research and Characterization Study (SEARCH) was initiated in mid-1998 as a 7-year observation and research program with a broader focus including aerosols and an expanded geographical coverage in the Southeast. The monitoring network comprises four urban-rural (or urban-suburban) site pairs at locations along the coast of the Gulf of Mexico and inland, including two moderately sized and two major urban areas (Pensacola, FL; Gulfport, MS; Atlanta, GA; and Birmingham, AL). The sites are equipped with an extensive suite of instruments for measuring particulate matter (PM), gases relevant to secondary O₃ and the production of secondary aerosol particles, and surface meteorology. The measurements taken to date have added substantially to the knowledge about the temporal behavior and geographic variability of tropospheric aerosols in the Southeast. Details are presented in four papers to follow.     

An Environmental Decision-Making Tool for Evaluating Ground-Level Ozone-Related Health Effects

Abstract

A computer model called the Ozone Risk Assessment Model (ORAM) was developed to evaluate the health effects caused by ground-level ozone (O₃) exposure. ORAM was coupled with the U.S. Environmental Protection Agency’s (EPA) Third-Generation Community Multiscale Air Quality model (Models-3/CMAQ), the state-of-the-art air quality model that predicts O₃ concentration and allows the examination of various scenarios in which emission rates of O₃ precursors (basically, oxides of nitrogen [NO_x] and volatile organic compounds) are varied. The principal analyses in ORAM are exposure model performance evaluation, health-effects calculations (expected number of respiratory hospital admissions), economic valuation, and sensitivity and uncertainty analysis through a Monte Carlo simulation. As a demonstration of the system, ORAM was applied to the eastern Tennessee region, and the entire O₃ season was simulated for a base case (typical emissions) and three different emission scenarios. The results indicated that a synergism occurs when reductions in NO_x emissions from mobile and point sources were applied simultaneously. A 12.9% reduction in asthma hospital admissions is expected when both mobile and point source NO_x emissions are reduced (50 and 70%, respectively) versus a 5.8% reduction caused by mobile source and a 3.5% reduction caused by point sources when these emission sources are reduced individually.     

Perfluoroalkyl carboxylates and sulfonates and precursors in relation to dietary source tracers in the eggs of four species of gulls (Larids) from breeding sites spanning Atlantic to Pacific Canada

In the present study, we identified and examined the spatial trends, sources and dietary relationships of bioaccumulative perfluorinated sulfonate (PFSA; C(6), C(8), and C(10) chain lengths) and carboxylate (PFCA; C(6) to C(15) chain lengths) contaminants, as well as precursor compounds including several perfluorinated sulfonamides, and fluorotelomer acids and alcohols, in individual eggs (collected in 2008) from four gull species [glaucous-winged (Larus glaucescens), California (Larus californicus), ring-billed (Larus delawarensis) and herring (Larus argentatus) gulls] from 15 marine and freshwater colony sites in provinces across Canada. The pattern of PFSAs was dominated by perfluorooctane sulfonate (PFOS; >89% of ΣPFSA concentration) regardless of egg collection location. The highest ΣPFSA concentrations were found in the eggs collected in the urbanized areas in the Great Lakes and the St. Lawrence River area [Big Chicken Island 308 ng/g ww, Toronto Harbour 486 ng/g ww, and Ile Deslauriers (HG) 299 ng/g ww]. Also, eggs from all freshwater colony sites had higher ΣPFSA concentrations, which were significant (p<0.05) in many cases, compared to the marine sites with the exception of the Sable Island colony in Atlantic Canada off the coast of Nova Scotia. C(6) to C(15) chain length PFCAs were detected in the eggs, although the pattern was variable among the 15 sites, where PFUnA and PFTrA dominated the pattern for most colonies. Like the ΣPFSA, the highest concentrations of ΣPFCA were found in the eggs from Big Chicken Island, Toronto Harbour, Ile Deslauriers (HG), and Sable Island, although not all freshwater sites had higher concentrations compared to marine sites. Dietary tracers [δ(15)N and δ(13)C stable isotopes (SIs)] revealed that PFSA and PFCA exposure is colony dependent. SI signatures suggested that gulls from most marine colony sites were exposed to PFCs via marine prey. The exception was the Mandarte Island colony in Pacific British Columbia, where PFSA and PFCA exposure appeared to be via terrestrial and/or freshwater prey consumption. The same was true for the freshwater sites where egg SIs suggested both aquatic and terrestrial prey consumption as the source for PFC exposure depending on the colony. Both aquatic (marine and freshwater) and terrestrial prey are likely sources of PFC exposure to gulls but exposure scenarios are colony-specific.     

Evaluating and reducing a model of radiocaesium soil-plant uptake

An existing model of radiocaesium transfer to grasses was extended to include wheat and barley and parameterised using data from a wide range of soils and contact times. The model structure was revised and evaluated using a subset of the available data which was not used for model parameterisation. The resulting model was then used as a basis for systematic model reduction to test the utility of the model components. This analysis suggested that the use of 4 model variables (relating to radiocaesium adsorption on organic matter and the pH sensitivity of soil solution potassium concentration) and 1 model input (pH) are not required. The results of this analysis were used to develop a reduced model which was further evaluated in terms of comparisons to observations. The reduced model had an improved empirical performance and fewer adjustable parameters and soil characteristic inputs.     

Forest-ecological consequences of fires in light conifer forests of Transbaikalia

Consideration is given to the results of studies on the postfire dynamics of Transbaikal forests, which are formed under conditions of highly arid climate and extreme pyrological regime. Data are presented on tree die-off and recruitment in naturally burned forests and in test stands affected by creeping fires differing in intensity. The hydrothermal regime of soils, precipitation runoff, and its multifactor models are discussed. It is shown that fires aggravate moisture deficiency on mountain slopes, impair the productivity of tree stands, and cause their digression. The statistics of forest fires and the risk of lightning fires are analyzed.     

Interaction of ant species in associations: An attempt to formalize behavioral characters

Behavioral adaptations of ant species were studied in associations of different biotopes in the Crimean Mountains. The pattern of an association was found to depend on the mode of the territorial behavior of dominant species, irrespective of their number. The dominance hierarchy was more strict in monodominant than in bidominant associations. Ant species demonstrated different behavioral strategies, plasticity of foraging, and avoidance of aggressive encounters. A method for formalizing interspecies relationships and a model describing stochastic properties of the biological system are proposed, which can be useful in solving various ethological and ecological problems.     

Integrated biological responses of zebrafish (Danio rerio) to analyze water quality in regions under anthropogenic influence

This study analyzed water quality in regions around Patos lagoon (Southern Brazil) that are under anthropogenic pressure. Water samples were collected from five different sites, including one used as a source for human consumption (COR) and others known to be influenced by human activities (IP). Danio rerio (Teleostei, Cyprinidae) organisms were exposed for 24 h to these water samples, plus a control group. It was observed that: (1) reactive oxygen species levels were lower in COR and IP than in the control group; (2) glutamate-cysteine ligase (catalytic subunit) expression was higher in COR than in other sites; (3) exposure to all water samples affected long-term memory (LTM) when compared to control group. Thus, some water samples possess the ability to modulate the antioxidant system and to induce a decline in cognitive functions, as measured by LTM. The obtained results indicate that a combination of variables of different organization level (molecular, biochemical and behavioral) can be employed to analyze water quality in impacted regions.     

Role of black carbon in the distribution of polychlorinated dibenzo-p-dioxins/dibenzofurans in aged field-contaminated soils

Floodplain soils containing elevated levels of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) were collected from several locations along the Tittabawassee River (Michigan, USA). The PCDD/F profiles of these soils exhibited distinct congener patterns consistent with byproducts from either chloralkali manufacturing or chlorophenols productions. Black carbon (BC) particles were isolated for the first time from floodplain soil impacted by PCDD/Fs. Petrographic analysis showed that BC particles, including coal, oxidized coal, metallurgical coke, depositional carbon, coal tar/pitch, cenosphere, and charcoal, comprised approximately 30% by volume of the organic fraction with size range of 250 μm-2000 μm from a typical floodplain soil. The BC particles with anthropogenic origin such as pitch and coke associated with the chloralkali production process served as both the source and subsequent transporter for the highly hydrophobic PCDD/Fs. These anthropogenic BC particles were enriched with high levels of PCDFs, containing approximately 1000-fold the concentration found in the bulk soil. The strong association of PCDD/Fs with anthropogenic BC directly impacts the physicochemical and biological availability thus the risk associated with these hydrophobic organochlorines in soils and sediments.