Daniel R. Oros

Levoglucosan, a tracer for cellulose in biomass burning and atmospheric particles

Abstract The major organic components of smoke particles from biomass burning are monosaccharide derivatives from the breakdown of cellulose, accompanied by generally lesser amounts of straight-chain, aliphatic and oxygenated compounds and terpenoids from vegetation waxes, resins/gums, and other biopolymers. Levoglucosan and the related degradation products from cellulose can be utilized as specific and general indicator compounds for the presence of emissions from biomass burning in samples of atmospheric fine particulate matter. This enables the potential tracking of such emissions on a global basis. There are other compounds (e.g. amyrones, friedelin, dehydroabietic acid, and thermal derivatives from terpenoids and from lignin—syringaldehyde, vanillin, syringic acid, vanillic acid), which are additional key indicators in smoke from burning of biomass specific to the type of biomass fuel. The monosaccharide derivatives (e.g. levoglucosan) are proposed as specific indicators for cellulose in biomass burning emissions. Levoglucosan is emitted at such high concentrations that it can be detected at considerable distances from the original combustion source.

Identification and emission factors of molecular tracers in organic aerosols from biomass burning Part 1. Temperate climate conifers

Abstract Smoke particulate matter from conifers subjected to controlled burning, both under smoldering and flaming conditions, was sampled by high volume air filtration on precleaned quartz fiber filters. The filtered particles were extracted with dichloromethane and the crude extracts were methylated for separation by thin layer chromatography into hydrocarbon, carbonyl, carboxylic acid ester and polar fractions. Then, the total extract and individual fractions were analyzed by gas chromatography and gas chromatography–mass spectrometry. The major organic components directly emitted in smoke particles were straight chain aliphatic compounds from vegetation wax and diterpenoid acids (biomarkers) from resin. The major natural products altered by combustion included derivatives from phenolic (lignin) and monosaccharide (cellulose) biopolymers and oxygenated and aromatic products from diterpenoids. Other biomarkers present as minor components included phytosterols, both the natural and altered products, and unaltered high molecular weight wax esters. Polycyclic aromatic hydrocarbons (PAH) were also present, however, only as minor constituents. Although the concentrations of organic compounds in smoke aerosols are highly variable and dependent on combustion temperature, the biomarkers and their combustion alteration products are source specific. The major components are adsorbed or trapped on particulate matter and thus may be utilized as molecular tracers in the atmosphere for determining fuel type and source contributions from biomass burning.

Identification and emission factors of molecular tracers in organic aerosols from biomass burning Part 2. Deciduous trees

Abstract Smoke particulate matter from deciduous trees (angiosperms) subjected to controlled burning, both under smoldering and flaming conditions, was sampled by high volume air filtration on precleaned quartz fiber filters. The filtered particles were extracted with dichloromethane and the crude extracts were methylated for separation by thin layer chromatography into hydrocarbon, carbonyl, carboxylic acid ester and polar fractions. Then, the total extract and individual fractions were analyzed by gas chromatography and gas chromatography–mass spectrometry. The major organic components directly emitted in smoke particles were straight chain aliphatic compounds from vegetation wax and triterpenoid acids (biomarkers) from gums and mucilages. The major natural products altered by combustion included derivatives from phenolic (lignin) and monosaccharide (cellulose) biopolymers and oxygenated and aromatic products from triterpenoids. Steroid biomarkers and polycyclic aromatic hydrocarbons (PAH) were also present, however, as minor constituents. Although the concentrations of organic compounds in smoke aerosols are highly variable and dependent on combustion temperature, the biomarkers and their combustion alteration products are in these cases source specific. The major components are adsorbed or trapped on particulate matter and thus may be utilized as molecular tracers in the atmosphere for determining fuel type and source contributions from biomass burning.

ORGANIC TRACERS FROM WILD FIRE RESIDUES IN SOILS AND RAIN/RIVER WASH-OUT

The molecular compositions and alteration products of the major organic components in soils and litter subjected to controlled or wildfire burning, and subsequent erosion by rain and river transport have been determined by GC-MS. The major compound groups imparted to soils include n-alkanoic acids, n-alkanes, n-alkanols, phytosterols, and terpenoids. Biomarker tracer analysis indicates that organic compounds remain as internal lipid components of char and heavy particles and are deposited onto soil during wildfire and prescribed burning. The process of rain erosion and river transport releases some of these internal components into the surroundings where they are further subjected to biological alteration. The distributions and abundances ofhomologous compound series coupled with biomarker tracer analysis provides a chemical fingerprint which is useful for identifying the single or multiple plant species contributing organic matter by both thermal (burning) and biological processes. Such fingerprints are useful for tracking soils which are transported in the atmosphere by wind as suspended particles in dust storms and on land by rain erosion to rivers.

Identification of Molecular Tracers in Organic Aerosols from Temperate Climate Vegetation Subjected to Biomass Burning

Smoke particulate matter from temperate climate vegetation subjected to controlled burning, both under smoldering and flaming conditions, was sampled by high volume air filtration on precleaned quartz fiber filters. The filtered particles were extracted with dichloromethane and the crude extracts were methylated for separation by thin layer chromatography into hydrocarbon, car bonyl, carboxylic acid ester, and polar fractions, then analyzed by gas chromatog raphy and gas chromatography-mass spectrometry. The major organic components in smoke particles were straight chain aliphatic compounds from vegetation wax and diterpenoid acids (biomarkers) from gum bleed resin. The major natural products altered by combustion included derivatives from phenolic (lignin) and monosaccharide (cellulose) biopolymers and oxygenated and aromatic products from diterpenoids. Biomarkers present as trace components included triterpenoids and phytosterols, both the natural and altered products. Polycyclic aromatic hydrocarbons (...

Epicuticular Wax Compositions of Predominant Conifers of Western North America

The compositions of epicuticular waxes from conifers constituting the predom inant species of western North America were determined by GC and GC-MS. The primary components identified include alkanes, fatty acids, fatty alcohols, aldehydes, ketones, phytosterols, triterpenoids and wax esters. Average chain lengths (ACL) for alkanes in Oregon conifers decreased with increasing distance away from the Coastal range which suggests an adaptation by conifers to humid climate conditions. Differences in the chemical compositions make this information useful for chemotaxonomic purposes, for identifying natural organic aerosol input sources to the atmosphere, for comparison with the tracers in smoke emissions from burning of these biomass fuels, and for monitoring in assessment of global climate change

Molecular tracers for smoke from charring/burning of chitin biopolymer

Abstract Monosaccharide derivatives from the breakdown of cellulose are the major organic components of smoke particles emitted to the atmosphere from biomass burning. In urban areas a related biopolymer, chitin, may contribute markers to smoke from grilling/charring of crustacean seafood. 1,6-Anhydro-2-acetamido-2-deoxyglucose and the related degradation products from chitin can be utilized as specific and general indicator compounds for the presence of emissions from charring/burning of crustaceans in samples of atmospheric fine particulate matter. This enables the potential assessment of such cooking emissions in urban and rural areas. There are other compounds (e.g., thermal alteration derivatives from proteins and nucleic acids) which are additional key indicators in smoke from charring/burning of chitin. 1,6-Anhydro-2-acetamido-2-deoxyglucose is proposed as a specific indicator for chitin in biomass burning emissions. It is emitted at similarly high concentrations and emission rates as levoglucosan from cellulose burning that it should be detectable in certain indoor and urban atmospheres.

Distributions and sources of polycyclic aromatic hydrocarbons in surface sediments from the Cross River estuary, S.E. Niger Delta, Nigeria.

Polycyclic aromatic hydrocarbon (PAH) analyses of surface sediments from the Cross River estuary by gas chromatography–mass spectrometry indicated natural diagenetically derived PAHs in the upper estuary, with minor and variable amounts of petrogenic and combustion-derived PAHs from human activities (lower estuary). The occurrence of significant amounts of perylene (average 23% of all PAHs) with the diagenetic natural PAHs in the middle estuary bordered by mangrove forests supports its origin from terrestrial organic matter. The natural PAHs represent the highest percentage (average 76%) of the total PAHs in this tropical environment. The traditional geochemical parameters, including the petrogenic PAHs, confirmed trace petroleum contamination in the estuary. Specific PAH ratios such as Fl/Py and Fl/(Fl+Py) also support this source contribution.

Occurrence and Sources of Triterpenoid Methyl Ethers and Acetates in Sediments of the Cross-River System, Southeast Nigeria

Pentacyclic triterpenol methyl ethers (PTMEs), germanicol methyl ether (miliacin), 3-methoxyfern-9(11)-ene (arundoin), β-amyrin methyl ether (iso-sawamilletin), and 3-methoxytaraxer-14-ene (sawamilletin or crusgallin) were characterized in surface sediments of the Cross-River system using gas chromatography-mass spectrometry (GC-MS). Triterpenol esters (mainly α- and β-amyrinyl acetates and hexanoates, and lupeyl acetate and hexanoate) were also found. These distinct compounds are useful for assessing diagenesis that can occur during river transport of organic detritus. Poaceae, mainly Gramineae and Elaeis guineensis higher plant species, are proposed as primary sources for the PTMEs and esters in the sediments. PTMEs are biomarkers of specific higher plant subspecies, while the triterpenol esters are indicators of early diagenetic alteration of higher plant detritus.

The extent and significance of petroleum hydrocarbon contamination in Crater Lake, Oregon

In order to evaluate hydrocarbon inputs to Crater Lake from anthropogenic and natural sources, samples of water, aerosol, surface slick and sediment were collected and analyzed by gas chromatography-mass spectrometry (GC-MS) for determination of their aliphatic and aromatic hydrocarbon concentrations and compositions. Results show that hydrocarbons originate from both natural (terrestrial plant waxes and algae) and anthropogenic (petroleum use) sources and are entering the lake through direct input and atmospheric transport. The concentrations of petroleum hydrocarbons range from low to undetectable. The distributions and abundances of n-alkanes, polycyclic aromatic hydrocarbons (PAH) and unresolved complex mixture (UCM) from petroleum are similar for all surface slick sampling sites. The estimated levels of PAH in surface slicks range from 7–9 ng/m2 which are low. Transport of petroleum-derived hydrocarbons from the lake surface has resulted in their presence in some sediments, particularly near the boat operations mooring (total petroleum HC = 1440 µg/kg, dry wt. compared to naturally derived n-alkanes, 240 µg/kg, dry wt.). The presence of biomarkers such as the tricyclic terpanes, hopanes and steranes in shallow sediments further confirms petroleum input from boat traffic. In the deep lake sediments, petroleum hydrocarbon concentrations were very low (16 µg/kg, dry wt.). Very low concentrations of PAH were detected in shallow sediments (17–40 µg/kg at 5 m depth near the boat operations) and deep sediments (3–15 µg/kg at 580 m depth). The individual PAH concentrations in sediments (µg/kg or ppb range) are at least three orders of magnitude less than reported threshold effects levels (mg/kg or ppm range, test amphipod Hyalella azteca). Therefore, no adverse effects are expected to occur in benthic biota exposed to these sediments. Boating activities are leaving a detectable level of petroleum in surface waters and lake sediments but these concentrations are very low.