Lipid/bitumen maturation by hydrothermal activity in sediments of Middle Valley, leg 139

The accelerated diagenesis, maturation, and catagenesis of organic matter to hydrothermal petroleum was studied in sediments from Ocean Drilling Program Leg 139 in Middle Valley, northern Juan de Fuca Ridge. Sediments at Sites 855 and 856 have experienced high heat flow resulting in accelerated diagenesis of the immature organic matter without product migration. Ruid migration through these sediments has resulted in an influx of mature organic components, yielding diverse bitumen mixtures. At Site 857 the alteration has occurred in situ to the catagenetic stage and at Site 858, the hottest holes, the hydrothermal petroleums have migrated after generation. Maturation for the rc-alkanes proceeds from high CPI values to 250 dalton)

Organic compounds in biomass smoke from residential wood combustion: Emissions characterization at a continental scale

Wood smoke in the atmosphere often accounts for 20–30% of the ambient fine-particle concentrations. In communities where wood is burned for home heating, wood smoke can at times contribute the majority of the atmospheric fine-particle burden. Chemical mass balance receptor models that use organic compounds as tracers can be used to determine the contributions of different emission sources, including wood smoke, to atmospheric fine-particle samples. In order for organic chemical tracer techniques to be applied to communities across the United States, differences in wood smoke composition that arise from differences in the type of wood burned in various regions must be understood. A continental-scale accounting of particulate organic compound emissions from residential wood combustion has been constructed which helps to quantify the regional differences in wood smoke composition that exist between different parts of the United States. Data from a series of source tests conducted on 22 North American wood species have been used to assemble a national inventory of emissions for more than 250 individual organic compounds that are released from wood combustion in fireplaces and wood stoves in the United States. The emission rates of important wood smoke markers, such as levoglucosan, certain substituted syringols and guaiacols, and phytosterols vary greatly with wood type and combustor type. These differences at the level of individual wood type and combustion conditions translate into regional differences in the aggregate composition of ambient wood smoke. By weighting the source test results in proportion to the availability of firewood from specific tree species and the quantities of wood burned in each locale, it is possible to investigate systematic differences that exist between wood smokes from different regions of North America. The relative abundance of 10 major wood smoke components averaged over the emissions inventory in different regions of the United States is computed and then used to illustrate the extent to which wood smoke composition differs from region to region in North America

Global comparisons of organic matter in sediments across the Cretaceous/Tertiary boundary

The Cretaceous/Tertiary (K/T) boundary is marked by extensive changes in the sedimentary fossil record of continental and marine life. Organic matter in sediments from above and below the K/T boundary has been studied to identify consequences of the biotic extinctions and of the changes in biological productivity which occures at this time. Data from locations encompassing a variety of marine paleoenvironments were examined to assess the gl;obal extent and local expressions of these biological changes. Characterizations of organic included Rock-Eval pyrolysis, stable carbon isotope ratios, and distributions of extractable biomakers. In general, organic carbon concentrations are a few tenths of a percent in the chalks and marls above and below the K/T boundary; in some boundary clay samples concentrations up to 5% are found. The elevated amounts near the boundary result from oxidation of marine organic matter, consequent dissolution of carbonates, and concentration of the surviving organic matter. At all locations, the organic matter has been microbially reworked and evidently was deposited in oxidizing environments. Carbon isotope shifts in open marine sediments suggest biological productivity was depressed following the K/T boundary. Repetition of these changes at different verifies the global extent of the boundary event, yet local variations in its expression are evident.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28909/1/0000746.pd

Dissolved organic carbon in interstitial waters from sediments of Middle Valley, leg 139

High-temperature combustion oxidation measurements of nonvolatile dissolved organic carbon (DOC) have been determined for pore waters from sediments of Middle Valley, Ocean Drilling Program Leg 139, as well as for overlying and near-bottom seawater. The DOC values in the interstitial waters are generally greater than those in the overlying water column, ranging from 0.1 to 86 mg/L of carbon. Some of the profiles of DOC in the pore waters are similar to total organic carbon, total carbon, and total inorganic carbon profiles. At Site 855 the concentrations of DOC in interstitial waters generally decrease with depth. DOC maxima at shallow depths of Site 858 are probably enriched due to higher temperature alteration of organic matter. At Sites 856 and 857, besides the decreasing trend above, the DOC increases at greater depths, also due to the hydrothermal activity. The values of DOC correlate with MnO and MgO profiles in Hole 856B. The changes below 30 mbsf in the DOC depth profiles of Site 858 parallel those of the volatile hydrocarbon gases

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

Sugars as source indicators of biogenic organic carbon in aerosols collected above the Howland Experimental Forest, Maine

Author Posting. © The Authors, 2005. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Atmospheric Environment 40 (2006): 1694-1705, doi:10.1016/j.atmosenv.2005.11.001.Bulk aerosols (> 1 μm) were collected continuously above the canopy at the Howland Experimental Forest, Maine, USA from May to October 2002. Each sample integrated over an approximately two-week period. Mono- and disaccharide sugars were extracted using a microscale technique and were analyzed as their TMS derivatives by GC-MS. Concentrations of total aerosol sugars ranged from 10 to 180 ng m-3. Glucose was the most abundant sugar (40-75% of the total sugars). The monosaccharides arabinose, fructose, galactose, mannose, arabitol and mannitol, and the disaccharides sucrose, maltose and mycose (aka trehalose) were also present in lower concentrations. The sugar composition in the aerosols varied seasonally. Fructose and sucrose were prevalent in early spring and decreased in relative abundance as the growing season progressed. Sugar polyols (arabitol and mannitol) and the disaccharide mycose (a fungal metabolite) were more prevalent in autumn during the period of leaf senescence. The changes in the sugar composition in the aerosol samples appear to reflect the seasonality of sugar production and utilization by the ecosystem. Plant waxes were present as significant components also indicating an input from biogenic background. Smoke plumes from Quebec forest fires passed over the Howland site in early July 2002. Levoglucosan, a biomarker of biomass burning, increased by an order of magnitude in the aerosol samples collected during this time. Glucose, mannose, arabinose, galactose, and also, plant waxes increased in concentration by factors of 2-5 in the smoke-impacted samples, indicating that wildfires enhance atmospheric emissions of uncombusted organic compounds. In contrast, concentrations of fructose, sugar polyols and disaccharides were not significantly higher in the smoke-impacted samples and indicated that biomass burning was not a significant source of these compounds in the aerosols.This work was funded by a grant to MHC (DOE-NIGEC Grant 15460100) from the U.S. Department of Energy’s (DOE) National Institute for Global Environmental Change (NIGEC), through the NIGEC Northeast Regional Center at Harvard University

Mathematical modeling of atmospheric fine particle-associated primary organic compound concentrations

An atmospheric transport model has been used to explore the relationship between source emissions and ambient air quality for individual particle phase organic compounds present in primary aerosol source emissions. An inventory of fine particulate organic compound emissions was assembled for the Los Angeles area in the year 1982. Sources characterized included noncatalyst- and catalyst-equipped autos, diesel trucks, paved road dust, tire wear, brake lining dust, meat cooking operations, industrial oil-fired boilers, roofing tar pots, natural gas combustion in residential homes, cigarette smoke, fireplaces burning oak and pine wood, and plant leaf abrasion products. These primary fine particle source emissions were supplied to a computer-based model that simulates atmospheric transport, dispersion, and dry deposition based on the time series of hourly wind observations and mixing depths. Monthly average fine particle organic compound concentrations that would prevail if the primary organic aerosol were transported without chemical reaction were computed for more than 100 organic compounds within an 80 km × 80 km modeling area centered over Los Angeles. The monthly average compound concentrations predicted by the transport model were compared to atmospheric measurements made at monitoring sites within the study area during 1982. The predicted seasonal variation and absolute values of the concentrations of the more stable compounds are found to be in reasonable agreement with the ambient observations. While model predictions for the higher molecular weight polycyclic aromatic hydrocarbons (PAH) are in agreement with ambient observations, lower molecular weight PAH show much higher predicted than measured atmospheric concentrations in the particle phase, indicating atmospheric decay by chemical reactions or evaporation from the particle phase. The atmospheric concentrations of dicarboxylic acids and aromatic polycarboxylic acids greatly exceed the contributions that are due to direct emissions from primary sources, confirming that these compounds are principally formed by atmospheric chemical reactions

Determination of Organic Compounds Present in Airborne Particulate Matter

Fine organic aerosol samples (d_p ≤ 2.1 µm) were collected systematically during the entire year 1982 at four urban sites in the greater Los Angeles area and at one remote station: West Los Angeles, Downtown Los Angeles, Pasadena, Rubidoux, and San Nicolas Island. Samples were taken at 6-day intervals and composited to form monthly sample sets. The aerosol sample composites were subjected to high resolution gas chromatography (HRGC) and gas chromatography/rnass spectrometry (GC/MS). The objective is to quantify the abundance and seasonal variation of individual organic compounds that may be diagnostic for the contribution of particular emission sources to the ambient organic complex. More than 80 organic compounds are quantified, including the series of a-alkanes, g-alkanoic acids, n-alkenoic acids, n-alkanals, and aliphatic dicarboxylic acids, as well as aromatic polycarboxylic acids, diterpenoids, polycyclic aromatic hydrocarbons, polycyclic aromatic ketones and quinones, nitrogen-containing organic compounds, and other organics. Primary organic aerosol constituents are readily identified, revealing an annual pattern with high winter concentrations and low summer concentrations in the Los Angeles area. In contrast, dicarboxylic acids of likely secondary origin show a reverse pattern, with high concentration in late spring/early summer. The total ambient annual average dicarboxylic acids concentration shows a steady increase when moving in the prevailing summer downwind direction from the most western urban sampling site (West Los Angeles) to the farthest eastern sampling location (Rubidoux), with an increase from 199 ng m^(-3) at West Los Angeles to 312 ng m^(-3) at Rubidoux. The occurrence of aromatic polycarboxylic acids in the fine particulate matter is discussed in detail in this study, including possible sources and formation pathways. The total aromatic polycarboxylic acid concentration reveals elevated summer concentrations when compared to the annual concentration cycle, indicating increased formation or/and emissions in summertime. Polycyclic aromatic hydrocarbons (PAH's), without exception, show low summer and high winter concentrations; whereas, polycyclic aromatic ketones (PAK's) and quinones (PAQ's) show slightly increased input/formation during early summer, indicating possible atmospheric chemical reactions involving PAH's as precursor compounds. Molecular markers characteristic of wood smoke are identified, and their concentrations change by season in close agreement with prior estimates of the seasonal use of wood as a fuel. The total mass concentration of identified aerosol organic compounds ranges from about 650 ng m^(-3) (West LA) to about 760 ng m^(-3) (Downtown LA) on an annual basis. Subdividing the total identified masses into their single compound classes reveals that n-alkanoic acids and aliphatic dicarboxylic acids make up the main portions quantified, followed by aromatic polycarboxylic acids, n-alkanes, diterpenoid acids, and polycyclic aromatic hydrocarbons. This compilation of fine organic aerosol data on a molecular level provides an extensive catalog of the organic compounds quantified, covering an entire year. Further research is underway to characterize the organic aerosol released by primary emission sources in the Los Angeles area. That study will not only provide complete characterizations of these emissions sources on a molecular basis, but in addition will enable the identification and quantification of additional organic compounds in the same airborne particle samples which otherwise would have gone unidentified in the complexity of the organic matrix inherent in fine airborne particle samples. In the future, these data from the monitoring network can be used to evaluate the predictions of mathematical models for the atmospheric transport and reaction of organic aerosol constituents defined at a molecular level

Suspended particulate matter transport of polycyclic aromatic hydrocarbons in the lower Columbia River and its estuary

Analysis of suspended particulate material (SPM) collected from the Columbia River and its estuary in 2007–2008 revealed the ubiquitous presence of polycyclic aromatic hydrocarbons (PAHs) from several distinct sources. The two dominant ones were: (1) a suite of non-alkylated, three to five-ringed compounds derived from high temperature combustion and (2) perylene, a compound of diagenetic origin. A particle-selective, hydrodynamic trapping process explains how both PAH types become concentrated on both a particle weight and organic carbon basis in the estuarine turbidity maximum (ETM) by as much as 10 times relative to the riverborne particle source. The ETM is a transient sedimentary feature at the land-to-sea interface of river-dominated estuarine systems which, in the case of our study region, is located remotely from the likely site of initial PAH input. Particle normalized concentrations for PAH of notable environmental concern, such as fluoranthene, chrysene, and benzo[a]pyrene, exceeded the EPA-defined threshold effects level in all cases and were typically at, or above, the probable effects level. Comparison with results from studies for other waterways around the world indicates PAH concentrations in ETM-trapped particles from the Columbia River estuary are higher than those documented for SPM in waters of many far more industrialized and populated regions. Our refined understanding of PAH behavior in the Columbia River and its estuary should prove valuable for reliably modeling the transport and dispersal mechanism that is characteristic of other hydrophobic, particle associated persistent organic pollutants prevalent in this system, and for other river-dominated estuarine systems.This is the publisher’s final pdf. The article is copyrighted by Association for the Sciences of Limnology and Oceanography and published by John Wiley & Sons, Inc. It can be found at: http://www.aslo.org/lo/index.htm

Sources and hydrothermal alteration of organic matter in Quaternary sediments: A synthesis of studies from the Central Gulf of California

Deep sea drilling in the Central Gulf of California, a young and active spreading centre, shows that the high heat flow typical of these regions causes extensive alteration of sediment organic matter, especially near sills and above magma chambers where hydrothermal activity is concentrated. Even on the nearby passive margin, where there are no sills, heat flow is moderately high and hydrocarbon generation has begun in immature sequences. Migrating light hydrocarbons are detected especially where hydrothermal activity is concentrated. Thermogenic methane is more widespread, though not in the passive margin bordering the spreading centre. Despite the incidence of hydrocarbon generation and migration, the amounts of hydrocarbons involved are relatively small and apparently do not lead to commercially significant accumulations of petroleum.The organic matter in these sediments is mostly marine because the Gulf of California generally has low runoff from land and highly productive surface waters. Turbidites rich in terrigenous organic material are locally abundant in the mainly pelagic section in the Guaymas Basin. The highest concentrations of organic matter are found in laminated diatomites deposited on the Guaymas passive margin within the oxygen minimum zone.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25993/1/0000059.pd