Unresolved Complex Mixture Research Articles

Characteristics of organic compounds in aerosol particulate matter from Dhahran city, Saudi Arabia

Organic chemical pollutants in atmospheric particulate matter (PM) have a potential toxicity hazard resulting in human responses that vary from no discernible effect to premature death. The formation and sources of PM also affect air quality of metropolitan areas as well as climate change. The new developments and industrial activities in the Middle East, especially Saudi Arabia, are expected to contribute to the natural, regional, and anthropogenic input sources of organic matter (OM). Here we report the occurrence, concentrations and sources of organic tracers, including n-alkanes, polycyclic aromatic hydrocarbons (PAHs), plasticizers, and petroleum biomarkers, in ambient atmospheric PM from the city of Dhahran, Saudi Arabia. The major compounds were unresolved complex mixtures (UCM) of branched and cyclic hydrocarbons (489±296ngm−3), plasticizers (131±119ngm−3 for phenyl phosphates, 87±42ngm−3 for phthalates), n-alkanes (73±53ngm−3), hopane biomarkers (11±8ngm−3), n-alkanones (6.7±6.3ngm−3), PAHs (2.0±2.1ngm−3), n-alkanols (1.2±1.2ngm−3), sterane biomarkers (0.4±0.3ngm−3), and sterols (0.5±0.4ngm−3). Obviously, UCM and plasticizers were the major components (56±9% and 26±10% of the total extracts, respectively) in the PM of Dhahran, which might have adverse public health effects. The major sources of this OM are emissions from industrial factories north of the city, plastics and biomass burning, and petroleum product combustion (traffic/refining).

An examination of the fidelity of n-alkanes as a palaeoclimate proxy from sediments of Palaeolake Tianyang, South China

This study examines n-alkane distributions from a 120 m long borehole extracted from Palaeolake Tianyang, South China, which covers the last five glacial cycles. We aim to determine the palaeoclimatic/environmental fidelity of n-alkane distributions in bulk organic matter (OM) from this tropical sedimentary archive. The Tianyang lithostratigraphy reveals a deep-lake sequence (120–42 m) dominated by diatomite, overlain by shallow-lake and marsh sediments in the upper 42 m. The Carbon Preference Index (CPI, C23–C31) suggests that there is weak odd/even predominance (OEP) in long chain n-alkane distributions (C27–C31) in OM from deep lake sediments, and a strong OEP of long chain n-alkane distributions in OM from shallow lake sediments. The opposite characteristics are evident in short chain n-alkane distributions (C16–C20). These CPI values suggest different sources of organic carbon within the deep (dominantly diatom synthesis) and shallow lake (dominantly high plant input), but cannot help differentiate glacial from interglacial sediments. The Terrigenous-to-Aquatic Ratio (TAR) shows high values throughout interglacial sediments (>4) and low values in glacial sediments (<4), corresponding to a higher productivity of high plants during interglacials, and vice versa. The proportion of aquatic plant n-alkanes (Paq) also reveals a clear change between glacial (0.31–0.39) and interglacial periods (0.22–0.28) during shallow lake stage, indicating a reduction in terrestrial OM input during glacial periods relative to interglacial periods. There is a greater amount of Unresolved Complex Mixture (UCM) in glacial sediments than within interglacial sediments. We suggest that the above n-alkanes indexes are useful environmental/climatic indicators within Palaeolake Tianyang, despite the fact that some other indexes, like Average Chain Length (ACL), provide less definitive interpretations.

Resolving Biodegradation Patterns of Persistent Saturated Hydrocarbons in Weathered Oil Samples from the Deepwater Horizon Disaster

Biodegradation plays a major role in the natural attenuation of oil spills. However, limited information is available about biodegradation of different saturated hydrocarbon classes in surface environments, despite that oils are composed mostly of saturates, due to the limited ability of conventional gas chromatography (GC) to resolve this compound group. We studied eight weathered oil samples collected from four Gulf of Mexico beaches 12-19 months after the Deepwater Horizon disaster. Using comprehensive two-dimensional gas chromatography (GC × GC), we successfully separated, identified, and quantified several distinct saturates classes in these samples. We find that saturated hydrocarbons eluting after n-C22 dominate the GC-amenable fraction of these weathered samples. This compound group represented 8-10%, or 38-68 thousand metric tons, of the oil originally released from Macondo well. Saturates in the n-C22 to n-C29 elution range were found to be partly biodegraded, but to different relative extents, with ease of biodegradation decreasing in the following order: n-alkanes > methylalkanes and alkylcyclopentanes+alkylcyclohexanes > cyclic and acyclic isoprenoids. We developed a new quantitative index designed to characterize biodegradation of >n-C22 saturates. These results shed new light onto the environmental fate of these persistent, hydrophobic, and mostly overlooked compounds in the unresolved complex mixtures (UCM) of weathered oils.

Formation and identification of unresolved complex mixtures in lacustrine biodegraded oil from Nanxiang Basin, China.

A comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC × GC/TOFMS) method has been developed for the formation and identification of unresolved complex mixtures (UCMs) in lacustrine biodegraded oils that with the same source rock, similar maturity, and increasing degradation rank from Nanxiang Basin, China. Normal alkanes, light hydrocarbons, isoprenoids, steranes, and terpanes are degraded gradually from oil B330 to oil G574. The compounds in biodegraded oil (oil G574) have fewer types, the polarity difference of compounds in different types is minor, and the relative content of individual compounds is similar. All the features make the compounds in biodegraded oil coelute in GC analysis and form the raised “baseline hump” named UCMs. By injecting standard materials and analyzing mass spectrums of target compounds, it is shown that cyclic alkanes with one to five rings are the major components of UCMs. Furthermore, UCMs were divided into six classes. Classes I and II, composed of alkyl-cyclohexanes, alkyl-naphthanes, and their isomers, are originated from the enrichment of hydrocarbons resistant to degradation in normal oils. Classes III ~ VI, composed of sesquiterpenoids, tricyclic terpanes, low molecular steranes, diasteranes, norhopanes, and their isomers, are probably from some newly formed compounds during the microbial transformation of oil.

Two-dimensional correlation analysis and multivariate time series analysis as innovative tools for the study and the comparison of the hydrocarbon distributions in marine antarctic cores

In this paper we describe the use of innovative methods for the study of the hydrocarbon distribution in environmental samples such as marine sedimentary Antarctic cores. In the first and conventional step of this study, we determined by GC analysis the hydrocarbon markers which allow us to estimate the presence of biogenic, anthropogenic and petrogenic sources. These markers were the Carbon Preference Index (CPI), the Low Molecular Weight to High Molecular Weight (LMW/HMW), the pristane to phytane (Pry/Phy), the C17 to pristine (C17/Pri) and the C18 to phytane (C18/Phy) ratios, the presence of the so called unresolved complex mixtures (UCM), and the sum of two and three rings to the sum of higher ring (PAH(2.3)/PAH(4.6)) ratio. This part of the study showed the prevalent biogenic origin of hydrocarbons present in each sedimentary core with a minority presence of anthropogenic and pyrogenic sources of hydrocarbons. In the second and innovative step of this study we examined the GC chromatographic data sets of the cores by means of two-dimensional correlation analysis (2DCORR) techniques such as two-dimensional mapping (2DMAP) and two-dimensional disrelation (2DDIS) analysis. The results of 2DMAP showed a more homogeneous distribution of hydrocarbons present in the inshore core whereas the offshore core showed to be highly heterogeneous. 2DDIS results confirmed these findings describing these differences as related to the presence of a wide content of hydrocarbons within the C20–C40 range in the offshore core, depending reasonably on its specific stratigraphic and hydrologic conditions. At last, we applied Multivariate Time Series Analysis (MTSA) to study the effect of time on the spatial distribution of hydrocarbons along the sections of the cores. MTSA confirmed the different hydrological conditions present in the two sites. The innovative approach for the examination of hydrocarbon distribution by 2DCORR and MTSA techniques allows us to retrieve information which, on the opposite, can be hardly retrieved by means of the conventional examination of GC results based on comparisons of the hydrocarbon contents and markers.

Geochemistry of Paleozoic marine oils from the Tarim Basin, NW China. Part 4: Paleobiodegradation and oil charge mixing

Fifty-three oil samples from Paleozoic marine reservoirs of the Tarim Basin were analyzed by GC–FID and GC–MS to elucidate the influence of biodegradation and mixing on molecular compositions. Biodegradation has a major impact on many classes of compounds but the ultimate compositions and physical properties of the oil are influenced strongly by mixing with late oil charge, subsequent to the process of biodegradation. Almost all samples display biodegradation signatures, characterized by variable size of the unresolved complex mixture (UCM) and variable amounts of 25-norhopanes (25-NHs) and 17-nortricyclic terpanes (17-NTs). The ubiquitous occurrence of n-alkanes suggests that the petroleum accumulated in these fields is mainly a mixture of previously biodegraded oils with later migrated fresh oils. The unaltered late charge of oil, which has commingled with the initial biodegraded charge, gives the wide range of oil gravities and asphaltene contents observed.Most commonly used maturity and depositional environment diagnostic parameters in the saturated hydrocarbon fraction are affected by biodegradation. Based on the intensity of 25-NHs and 17-NTs, oils from the Tabei Uplift appear to have experienced a much greater degree of biodegradation than those from the Tazhong Uplift. However, we caution against the simplistic use of molecular indicators to define a specific level of biodegradation in this case study, as it may be somewhat misleading for physical property prediction. A wide range of estimated maturity values from different components provides an important clue for multiple charge and mixing interpretations. The relationship between the absolute concentrations of compound class and peak/hump ratios of the samples can potentially, qualitatively differentiate the pulse of inputs to the mixed oils. The positive correlation between the concentrations of a given compound class and peak/hump ratios may suggest that that class of compounds is most likely derived from the late charge after biodegradation, while the negative correlation may indicate compounds largely inherited from the early charge before biodegradation. Some compounds show almost no correlation between their concentrations and peak/hump ratios, implying more similar intensity of charge inherited from early pulse and amalgamated from later pulses. In some extremely biodegraded cases where UCM hump can also be diminished (not in present case study), the correlation between compound class concentrations and peak/hump ratios will be more complicated.

Sedimentary biomarkers along a contamination gradient in a human-impacted sub-estuary in Southern Brazil: A multi-parameter approach based on spatial and seasonal variability

The composition and seasonal variations of sedimentary organic matter were investigated along the Cotinga sub-estuary, located in Paranaguá Bay, a large South American estuary where urban activities and the primary Brazilian grain shipping port are sources of pollution. Steroids and hydrocarbons were analyzed in surface sediments collected during the austral winter (2008) and summer (2009) in three distinct sectors, along this sub-estuary in a presumed gradient of fecal contamination. Concentrations ranged from 0.28 to 7.33μgg−1 (in dry sample weight thereafter), <DL (below detection limit) to 57.2ngg−1 and <DL to 1.69μgg−1 for aliphatic hydrocarbons (ΣAHs), polycyclic aromatic hydrocarbons (ΣPAHs) and coprostanol, respectively. Petrogenic inputs may be considered as source of AHs due to the presence of unresolved complex mixture in the majority of sites; however the levels observed do not indicate oil contamination. The highest ΣPAHs concentrations were found during the summer in the middle sector of the sub-estuary but were below the threshold effect levels (TEL), suggesting the absence of contamination by PAHs. Selected PAH isomer ratios indicated pyrolytic sources, whereas fecal sterols indicated decreasing sewage contamination from sub-estuary to the open ocean. The absence of correlation between organic markers and grain-size parameters suggested no preferential deposition sites of organic matter in the study area. The Principal Components Analysis suggested spatial variation in the distribution of sterols and AHs; however, temporal variations were only evident in the distribution of PAHs.

Nonpolar lipid tracers in sediments from the Shatt al-Arab River of Iraq and the northwestern Arabian Gulf

Surface sediment samples from the Shatt al-Arab River of Iraq and northwestern coast of the Arabian Gulf were collected and analyzed to determine the characteristics, concentrations, distribution, and sources of nonpolar lipid compounds. The sediments were collected using a Van Veen grab sampler, dried, extracted with a mixture of dichloromethane/methanol, and analyzed by gas chromatography–mass spectrometry. The lipid compounds included n-alkanes (24.55 ± 44.35 μg g−1), methyl n-alkanoates (11.45 ± 9.45 μg g−1), hopanes (13.31 ± 13.46 μg g−1), steranes (15.63 ± 28.40 μg g−1), phthalates (36.99 ± 53.62 μg g−1), and unresolved complex mixture (315.84 ± 435.87 μg g−1). The major sources of these lipids were from anthropogenic petroleum inputs and plasticizers with lesser amounts from natural waxes of higher plants and microbial residues. Anthropogenic inputs from petroleum products ranged from 53 to 92 % of the total lipid compounds, whereas biogenic inputs were from 1.8 to 6.9 % for terrestrial plant wax and from 2.0 to 10.0 % for microbial detritus.

Characterization and sources of extractable organic matter from sediment cores of an urban lake (Tasik Perdana), Kuala Lumpur, Malaysia

The extractable organic matter of sediment samples from six sampling sites in Lake Perdana, Kuala Lumpur, was analyzed to characterize the source inputs. The analysis of aliphatic homologous series indicated that terrestrial higher plant waxes can be assigned as the major sources of the identified aliphatic components in the lake sediments. The presence of an unresolved complex mixture of branched and cyclic compounds and a series of hopanes ranging from C27 to C35 reflected the contamination by petroleum residues from urban vehicular emissions brought in by runoff and fallout. The steroids present included stenols and stanols and showed an input of organic matter from higher plants. The detected pentacyclic triterpenoids comprised oleanane, ursane, lupane and friedelane skeletons including unsaturated oxygenated, mono-, di- and triaromatic counterparts. They are recognized as biomarkers for angiosperms. The presence of des-A-triterpenoids and their aromatized derivatives as the major diagenetic products of triterpenoids reflected the degradation of natural organic matter in the sediments occurring under mainly anoxic conditions. In addition, the presence of tetrahymanol and ββ-bishomohopan-32-ol indicated a minor algal/plankton and bacterial input to the sediments.

Spatial distribution and concentration assessment of total petroleum hydrocarbons in the intertidal zone surface sediment of Todos os Santos Bay, Brazil

The primary objective of this study was to investigate the concentrations and spatial distribution of the total petroleum hydrocarbons (TPHs) in the intertidal zone surface sediment of Todos os Santos Bay, Brazil, to assess the distribution and degree of contamination by TPHs, measure the level of TPH degradation in the surface sediment, and identify the organic matter sources. The surface sediment used in this study was collected in 50 stations, and TPHs, isoprenoid alkanes (pristane and phytane), and unresolved complex mixture (UCM) were analyzed by gas chromatography with a flame ionization detector. The total concentrations ranged from 0.22 to 40,101μgg(-1) dry weight and showed a strong correlation with the total organic carbon (TOC) content. The highest TPH concentrations were observed in samples from the mangrove sediments of a river located near a petroleum refinery. Compared with other studies in the world, the TPH concentrations in the intertidal surface sediment of Todos os Santos Bay were below average in certain stations and above average in others. An analysis of the magnitude of UCM (0.11 to 17,323μgg(-1) dry weight) and the ratios nC17/Pr and nC18/Ph suggest that an advanced state of oil weathering, which indicates previous contamination. The molar C/N ratios varied between 5 and 43, which indicate organic matter with a mixed origin comprising marine and continental contributions.

Occurrence, sources and transport pathways of natural and anthropogenic hydrocarbons in deep-sea sediments of the eastern Mediterranean Sea

Abstract. Surface sediments collected from deep basins (1018–4087 m depth) of the eastern Mediterranean Sea (Ionian Sea, southern Aegean Sea and northwestern Levantine Sea) were analyzed for aliphatic and polycyclic aromatic hydrocarbons as tracers of natural and anthropogenic inputs. Concentrations of total aliphatic hydrocarbons, n-alkanes and the unresolved complex mixture (UCM) of aliphatic hydrocarbons varied significantly, ranging from 1.34 to 49.2 μg g−1, 145 to 4810 ng g−1 and 0.73 to 36.7 μg g−1, respectively, while concentrations of total polycyclic aromatic hydrocarbons (PAHs) ranged between 11.6 and 223 ng g−1. Molecular profiles of determined hydrocarbons reflect a mixed contribution from both natural and anthropogenic sources in deep-sea sediments of the eastern Mediterranean Sea, i.e., terrestrial plant waxes, degraded petroleum products, unburned fossil fuels and combustion of grass, wood and coal. Hydrocarbon mixtures display significant variability amongst sub-regions, reflecting differences in the relative importance of inputs from various sources and phase associations/transport pathways of individual hydrocarbons that impact on their overall distribution and fate. Hydrocarbon concentrations correlated significantly with the organic carbon content of sediments, indicating that the latter exerts an important control on their transport and ultimate accumulation in deep basins. Additionally, water masses' circulation characteristics also seem to influence the regional features and distribution patterns of hydrocarbons. Our findings highlight the role of deep basins/canyons as repositories of both natural and anthropogenic chemical species.

CHARGING OF ORDOVICIAN RESERVOIRS IN THE HALAHATANG DEPRESSION (TARIM BASIN, NW CHINA) DETERMINED BY OIL GEOCHEMISTRY

Petroleum at Halahatang oilfield in the Halahatang Depression (Tabei Uplift, Tarim Basin, NW China) occurs within calcarenites and bioclastic limestones in the Middle Ordovician Yijianfang Formation (O2yj). The petroleum is sourced from intervals in the Upper Ordovician Lianglitage Formation (O3l), and reservoirs are sealed by Upper Ordovician – Silurian argillaceous limestones and marls. The charging history of Halahatang oilfield is however poorly understood. For this study, the geochemical characteristics of 17 oils from Ordovician reservoir rocks at Halahatang field were investigated by GC and GC‐MS. Oil‐oil correlation studies indicate that all the oils belong to a single mature oil population. Based on the co‐occurrence of an intact n‐alkanes series together with an unresolved complex mixture (UCM) and fully‐developed 25‐norhopanes in the same oil samples, as well as a bimodal distribution of homogenisation temperatures of aqueous fluid inclusions, it was concluded that the reservoir experienced two separate oil charge events. 1D basin modelling indicates that the early phase of charging occurred from about 412 to 409 Ma and the later phase from 11 to 9 Ma. Using molecular parameters as tracing indicators, the general direction of oil charging was deduced to be from south to north. The source kitchen is therefore inferred to be located to the south of the Halahatang oilfield, probably in the Shuntuoguole Uplift between the Awati and Manjiaer Depressions.

Applicability of Passive Sampling to Bioanalytical Screening of Bioaccumulative Chemicals in Marine Wildlife

Quantification of bioaccumulative contaminants in biota is time and cost-intensive and the required extensive cleanup steps make it selective toward targeted chemical groups. Therefore tissue extracts prepared for chemical analysis are not amenable to assess the combined effects of unresolved complex mixtures. Passive equilibrium sampling with polydimethylsiloxane (PDMS) has the potential for unbiased sampling of mixtures, and the PDMS extracts can be directly dosed into cell-based bioassays. The passive sampling approach was tested by exposing PDMS to lipid-rich tissue (dugong blubber; 85% lipid) spiked with a known mixture of hydrophobic contaminants (five congeners of tetra- to octachloro-dibenzo-p-dioxins). The equilibrium was attained within 24 h. Lipid-PDMS partition coefficients (Klip-PDMS) ranged from 20 to 38, were independent of hydrophobicity, and within the range of those previously measured for organochlorine compounds. To test if passive sampling can be combined with bioanalysis without the need for chemical cleanup, spiked blubber-PDMS extracts were dosed into the CAFLUX bioassay, which specifically targets dioxin-like chemicals. Small quantities of lipids coextracted by the PDMS were found to affect the kinetics in the regularly applied 24-h bioassay; however, this effect was eliminated by a longer exposure period (72 h). The validated method was applied to 11 unspiked dugong blubber samples with known (native) dioxin concentrations. These results provide the first proof of concept for linking passive sampling of lipid-rich tissue with cell-based bioassays, and could be further extended to other lipid rich species and a wider range of bioanalytical end points.

Detailed chemical characterization of unresolved complex mixtures in atmospheric organics: Insights into emission sources, atmospheric processing, and secondary organic aerosol formation

Recent studies suggest that semivolatile organic compounds (SVOCs) are important precursors to secondary organic aerosol (SOA) in urban atmospheres. However, knowledge of the chemical composition of SVOCs is limited by current analytical techniques, which are typically unable to resolve a large number of constitutional isomers. Using a combination of gas chromatography and soft photoionization mass spectrometry, we characterize the unresolved complex mixture (UCM) of semivolatile aliphatic hydrocarbons observed in Pasadena, California (~16 km NE of downtown Los Angeles), and Bakersfield, California, during the California Research at the Nexus of Air Quality and Climate Change 2010. To the authors' knowledge, this work represents the most detailed characterization of the UCM in atmospheric samples to date. Knowledge of molecular structures, including carbon number, alkyl branching, and number of rings, provides important constraints on the rate of atmospheric processing, as the relative amounts of branched and linear alkanes are shown to be a function of integrated exposure to hydroxyl radicals. Emissions of semivolatile branched alkanes from fossil fuel‐related sources are up to an order of magnitude higher than those of linear alkanes, and the gas‐phase OH rate constants of branched alkanes are ~30% higher than their linear isomers. Based on a box model considering gas/particle partitioning, emissions, and reaction rates, semivolatile branched alkanes are expected to play a more important role than linear alkanes in the photooxidation of the UCM and subsequent transformations into SOA. Detailed speciation of semivolatile compounds therefore provides essential understanding of SOA sources and formation processes in urban areas.

Revisiting hydrocarbons source appraisal in sediments exposed to multiple inputs

The aim of this work was to test the efficiency of statistical methods as compared to the traditional diagnostic ratios to improve hydrocarbon source identification in sediments subjected to multiple inputs. Hydrocarbon determination in Guanabara Bay sediments pointed out high degradation and ubiquitous petrogenic pollution through the presence of high unresolved complex mixture. Polycyclic aromatic hydrocarbon (PAHs) ratios suggested pervasive contamination derived from combustion in all sediments and failed discriminating samples despite the specificity of sources in different sampling sites. Principal component analysis (PCA) effectively distinguished the petrogenic imprint superimposed to the ubiquitous combustion contamination, since this technique reduces the influence of PAHs distribution which is common to all samples. PCA associated to multivariate linear regression (MLR) allowed a quantitative assessment of sources confirming predominance of the pervasive contaminant component superimposed to a generalized petrogenic imprint. The pervasive component derives from combustion contributions as well as from differential PAHs degradation.

Organic geochemistry and depositional environments of Eocene coals in northern Anatolia, Turkey

This study is the first attempt which provides information regarding the organic geochemical, biomarker and petrographical characteristics of the Eocene coal deposits found in the Yeniçeltek, Eskiçeltek, Armutlu (Amasya), Aspiras (Kastamonu) and Salıpazarı (Bolu) fields in the northern part of Turkey.Proximate analyses including total ash and total sulphur contents and upper heat values of the coal samples from each fields exhibit significant differences. The Armutlu coal samples have the highest ash value (average 42.25%) and represented by relatively low upper calorific value (3868kcal/kg). In contrary, the Salıpazarı coal samples have the lowest ash content (average 3.37%) and the highest upper calorific value (7250kcal/kg). The average total % sulphur contents of all samples are generally high and quite different for each field. Total sulphur contents of Eskiçeltek, Yeniçeltek and Armutlu samples are similar and vary from 1.01% to 1.86. Samples from Aspiras and Salıpazarı fields have high total sulphur contents as 6.29% and 13.82%, respectively. Based on the vitrinite reflectance values, all coals are in the diagenetic stage and their coalification degrees are subbituminous A or high volatile bituminous C for the Yeniçeltek (0.55% Ro), Eskiçeltek (0.50% Ro) and Armutlu (0.50% Ro) coals, and subbituminous C for the Salıpazarı (0.39% Ro) coals, and lignite for the Aspiras (0.36% Ro) coals.All samples have high Total Organic Carbon (TOC) values, but low bitumen/TOC ratios. The average TOC values of Yeniçeltek, Eskiçeltek, Armutlu, Aspiras and Salıpazarı fields are 49.67%, 68.51%, 35.35%, 46.27% and 66.47%, respectively. Extraction analysis applied to one sample from each field yielded very low bitumen/TOC values ranging from 0.01%, to 0.07. The Hydrogen Index values of the Yeniçeltek, Eskiçeltek and Salıpazarı samples between 272mgHC/gTOC and 329mgHC/gTOC indicate that their organic matter type is Type II kerogen, whereas the other coal samples have Type III and Types II–III kerogen. Gas chromatograms indicate dominant odd-carbon-number n-alkanes, indicating terrestrial organic matter.The parameters obtained from mass spectrometer data on m/z 191 and m/z 217 indicate that the Yeniçeltek and Eskiçeltek coals were deposited in suboxic lakes or lacustrine swamps; the Armutlu and Aspiras coals were deposited in suboxic brackwater swamps (paralic environment); and the Salıpazarı coals were deposited in suboxic lakes or lacustrine swamps.An Unresolved Complex Mixture (UCM) observed in the gas chromatograms display immature organic matter and biodegradation. The Tmax, mean reflectance and biomarker maturity data show that coal samples are thermally immature.

Rapid column chromatography separation of alkylnaphthalenes from aromatic components in sedimentary organic matter for compound specific stable isotope analysis

A rapid, small scale method for separating alkylnaphthalenes from aromatic fractions in sedimentary organic matter, named two-step column chromatography, is described using alumina as the stationary phase. The entire process operates using minimal amounts of solvents and alumina, with sample sizes of as little as 1mg and a duration of 30min. The results monitored by gas chromatography-mass spectrometry showed that clean alkylnaphthalenes and biphenyls can be obtained that are free of unresolved complex mixture (UCM), monoaromatics and triaromatics, which allows accurate measurement of compound specific stable isotope data. This method provides rapid sample processing suitable for routine analysis in organic geochemistry to better extract the geological and geochemical information carried by alkylnaphthalenes in sedimentary organic matter.

Ardra profiles of bacteria and archaea in mangrove sediments with different levels of contamination in the estuarine complex of Paranaguá, Brazil

The mangrove's sediments from the coastal areas under human activities may contain significant contaminations by hydrocarbons, even when there are no visual evidences of it. The microorganisms are essential to these ecosystems, especially in the control of their chemical environment. Sediment samples were collected in two regions under different environment conditions (pristine and contaminated) of the Paranaguá Estuarine Complex (Paranaguá Bay and Laranjeiras Bay), Brazil. Aliphatic hydrocarbons were determined by the GC-FID to assess the status of contamination of the studied areas. The total DNA was extracted from these samples. The 16S rRNA gene was amplified by the PCR reactions with the pair of primers 21F and 958R for the archaeal domain, and 27F and 1492R for the bacterial domain. Comparisons of communities were made by the ARDRA technique, using the HinfI restriction enzyme. The phosphate concentration showed significant differences between the two regions. The aliphatic hydrocarbons analysis showed the presence of unresolved complex mixture (UCM), an indicator of oil contamination, in the samples from the Paranaguá Bay, which was corroborated by the concentration of total aliphatic hydrocarbons. The ARDRA profile indicated that the structure of archaeal and bacterial communities of the sampled areas was very similar. Therefore, the anthropogenic influences in the Paranaguá Bay showed to be not sufficient to produce disturbances in the prokaryotic dominant groups.

Source apportionment of polycyclic aromatic hydrocarbons in surface sediment of mud areas in the East China Sea using diagnostic ratios and factor analysis

Polycyclic aromatic hydrocarbons (PAHs) and aliphatic hydrocarbons (AHs) have been quantified for surface sediments collected from the East China Sea (ECS). Our results showed that relatively high levels of PAHs and AHs occurred in both the inner and outer mud areas, while their concentrations at the control site were much lower. AHs for all samples were dominated by the unresolved complex mixture (UCM). Results from diagnostic ratios revealed that sedimentary PAHs were mainly originated from mixed combustion residues of biomass, coal, and petroleum. Combustion residues of petroleum and oil were responsible for the presence of high AHs concentrations. We also conducted factor analysis (FA) to further characterize the PAH and AH sources. Four factors were identified based on the loading of components and attributed to coal and wood combustion (Factor 1), traffic-related sources (Factor 2), petrogenic source (Factor 3) and natural gas combustion (Factor 4).

Sources and preservation of organic matter in soils of the wetlands in the Liaohe (Liao River) Delta, North China

Total organic carbon, total nitrogen, δ13Corg, δ15N, and aliphatic and polyaromatic hydrocarbons of fifty-five soil samples collected from the coastal wetlands of the Liaohe Delta were measured, in order to determine the sources and possible preservation of organic matter (OM). The δ15N and δ13Corg values in the samples ranged from 3.0‰ to 9.4‰ and from −30.4‰ to −20.3‰, respectively, implying that the OM in the soils is predominantly derived from C3 plant. The long-chain n-alkanes had a strong odd-over-even carbon number predominance, suggesting a significant contribution from waxes of higher plants. The ubiquitous presence of unresolved complex mixture, alkylated polycylic aromatic hydrocarbons and typical biomarkers of petroleum hydrocarbons (pristane, phytane, hopanes and steranes) indicates that there is a contribution of petroleum hydrocarbons to the organic carbon pool in the wetland soils. P. australis-vegetated wetlands have strong potentials for the preservation of organic carbon in the wetlands.