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EEMS2015 organizing committee
Published in Yeping Wang, Jianhua Zhao, Advances in Energy, Environment and Materials Science, 2018
Saturated hydrocarbon in marine bottom sedi- ments mainly consists of n-alkanes, isoprenoids, steranes, terpanes and biomarkers. Their refined molecular components and distribution charac- teristics directly indicate primary organic matter source, bacterial degradation, sedimentary envi- ronment, seabed oil and gas shows (Brassell et al, 1986; Wolff et al, 1986; Wang Tieguan et al, 1995). Unresolved Complex Mixture (UCM) in saturated hydrocarbon is formed by bacterial biodegrada- tion of petroleum; in the extract from modern sediments, fraction chromatogram of saturated hydrocarbon has UCM, which is regarded to be an existence evidence of petroleum organic matter. UCM in crude oil contains 250,000 compounds (Sutton et al, 2005), with obvious upheaval in crude oil chromatogram subject to biodegradation (Peters et al, 2005). These almost indistinguish- able compounds may contain a lot of undiscov- ered organic geochemistry information (Gough & Rowland, 1991).
Tar Ball Formation and Distribution
Published in James R. Payne, Charles R. Phillips, Petroleum Spills in the Marine Environment, 1985
James R. Payne, Charles R. Phillips
Wade et al. (1976) analyzed a number of smaller tar particles (0.3 μm to 1,0 mm diameter) by gas chromatography and infrared spectrometry and found that the pelagic tar samples averaged about 32% water (with a range of 11 to 44%) and 68% dry weight material. Butler et al. (1973) found that tar lumps from the Atlantic Ocean typically contained about 25% water by weight. An average of 53% of the wet tar was soluble in benzene (range: 31 to 89%), and this material accounted for approximately 78% of the average dry weight of the samples. The benzene insoluble fraction of tar possibly included inorganic salts, non-organic debris, and higher molecular weight material. The wet tar samples averaged about 16% total hydrocarbon material, and the remaining weight percentage included non-hydrocarbon organic material or hydrocarbons not detected by their procedures (for example, hydrocarbons less than nC-14 and greater than nC-38). Jeffrey et al. (1973) found that Gulf of Mexico pelagic tar samples contained an average 26% asphaltenes based on the dry weight of sample. The gas chromatographic analyses showed that the predominant hydrocarbon weight percent was from components in the unresolved complex mixture (average: 79%; range: 67–97%) which includes both aromatic and cyclo paraffinic compounds. Varying degrees of resolved alkanes were observed in the different samples, with several samples showing no resolved peaks over the UCM and one sample showing an evenly repeating series of alkanes from nC-15 to nC-34. A number of other samples contained alkanes only above nC-25, with evidence of persistent pristane and phytane suggesting microbial degradation of the lower molecular weight normal paraffins. Infrared analyses showed that of the eight samples considered, all but two contained aromatic hydrocarbons. Van Vleet et al. (1983) reported that 40% of the tar ball samples collected in the Gulf of Mexico contained a bimodal distribution of n-alkanes within the ranges of nC-19 to nC-20 and from nC-29 to nC-35; 60% of the samples contained a unimodal distribution of n-alkanes with a maximum from nC-18 to nC-28. The nC-17/pristane values ranged from 0.14 to 4.6, whereas, the nC-18/phytane values ranged from 0.31 to 5.2. These chromatographic characteristics suggested that tar balls originated from multiple sources (e.g., crude oil sludge from tanker washings and refined products from tanker ballast operations), and that the tar balls had been degraded extensively by bacteria, whereas other samples showed very little microbial degradation. Cordes et al. (1980) analyzed tar balls from the South Atlantic Bight which contained approximately 30% polycyclic aromatic hydrocarbons. The primary compound in this fraction was perylene, which the authors suggested was highly resistant to weathering.
Unresolved complex mixtures of petroleum hydrocarbons in the environment: An overview of ecological effects and remediation approaches
Published in Critical Reviews in Environmental Science and Technology, 2021
Kavitha Ramadass, Saranya Kuppusamy, Kadiyala Venkateswarlu, Ravi Naidu, Mallavarapu Megharaj
Most contaminated soils, however, contain environmentally weathered hydrocarbon compounds which are often present in the form of an “unresolved complex mixture” (UCM) (Farrington & Quinn, 2015; Jeon et al., 2017). Collectively, these UCMs are commonly referred to as the “hump” in analytical gas chromatograms (Gebbayin et al., 2018). It has been shown that the natural degradation of petroleum products in crude oil results in a substantial increase in the concentration of UCMs (Hu et al., 2018; Meredith et al., 2000). Several studies have further indicated that UCMs accumulate in marine organisms, subsequently causing ecotoxicological effects, and indirectly affecting human health (Donkin et al., 2003; Petersen et al., 2017; Scarlett et al., 2007; Vane et al., 2017). Although many environmental samples that have been found to contain large amounts of UCMs are considered important, very little attention was paid to understand their nature and toxic potential until the last 30 years (Gough & Rowland, 1990; Hu et al., 2018; Rowland et al., 2001).
Investigation of some recycled oils as fluids for polyurea greases
Published in Petroleum Science and Technology, 2019
Refaat A. El-Adly, Ashraf Y. El-Naggar, Modather F. Hussein, Bassem M. Raafat
Capillary gas chromatography (CGC) is one of the best techniques used for the analysis of the petroleum oils. The gas chromatography fingerprints for lube recycled oil R1, R2 and R3 are shown in Figure 1, from the GC fingerprint, the broadband represents the unresolved complex mixture (UCM) that rises above the baseline on gas chromatograms, the UCM includes heavy naphthenes, heavy aromatics and resins and these data represented in Table 1. In addition, the gas chromatographic pattern of the studied recycled oils shows higher paraffin percentages in case R1than R3 representing as the peaks over the UCM hump, in other words the area of the unresolved component mixturewas found higher in case R3 than R1. This may be due to the formation of polymeric materials in the heavy fraction than lighter one.
Assessment and ecological indicators of total and polycyclic aromatic hydrocarbons in the aquatic environment of lake Manzala, Egypt
Published in Journal of Environmental Science and Health, Part A, 2018
Ahmed A. El-Kady, Terry L. Wade, Stephen T. Sweet
For aliphatic hydrocarbons, the recoveries of laboratory blank spike (2,000 ng g−1 spike) ranged from 87.5% to 101.5%. Recoveries of target compounds in spiked sediment samples ranged from 83.1% to 91.2% for C12 to C30n-alkanes. The method detection limit (MDL) for a 5 gram sample ranges from 7 to 52 ng g−1 for n-C10 to n-C35 with an average of 26.5 ng g−1 and a practical quantification limit of 40 ng g−1. Total resolved hydrocarbon (TR), unresolved complex mixture (UCM) and TPH method detection limits are 0.65, 15, and 15 μg g−1, respectively. The relative percent differences (RPD) between duplicate samples (range 2.2% and 4.2%) were within quality assurance guidelines.