Edward C. Ruth

Organic chemical characterization of sediment-trap particulates from San Nicolas, Santa Barbara, Santa Monica and San Pedro Basins, California☆

Particulate matter was collected during September–October, 1977, in particle traps suspended 30–60 m above the floor of San Nicolas, Santa Barbara, Santa Monica and San Pedro Basins, off the coast of southern California. The trap particulates were analyzed for C15–C35 hydrocarbons using gas chromatography (GC) and GC-mass spectrometry. Kerogens and humic acids were characterized by H/C, N/C, δ13C, δ15N and δ34S ratios, and by electron-spin resonance. Hydrocarbons arising from fresh and weathered petroleum, marine autochthonous and terrestrial sources were identified. The rates of petroleum deposition during the collection period followed the order: San Nicolas Basin < Santa Barbara Basin ~ Santa Monica Basin < San Pedro Basin, with the largest amount of weathered petroleum being deposited in San Pedro Basin. The rates of petroleum deposition are correlated more strongly with human activities such as shipping, and the discharge of municipal and industrial wastes, than with natural submarine oil seepage. Analyses of kerogens and humic acids indicate that the majority of the organic matter in the trap particulates is of marine origin. The water column overlying Santa Barbara Basin appears to have the highest marine productivity of the four basins studied.

Organic geochemistry of sediments from the continental margin off southern New England, U.S.A.--Part II. Lipids

Organic geochemical measurements of the lipid fraction, comparing saturated and aromatic hydrocarbons, fatty acids, alcohols and sterols, have been carried out on six sediments cores collected from the Atlantic shelf, slope and the rise areas to evaluate the cross-shelf transport of the organic carbon. The concentration of most of the organic compound classes studied is correlated with the total organic carbon, which decreases from the shelf through slope to the rise. Terrigenous carbon is recognizable even in the slope and rise sediments, but terrestrial influx decreases relative to marine generated lipids in the slope and rise organic matter. We estimate that approximately 50% of the shelf organic matter is exported to the slope. Data of sediment trap material collected at 1200 m from 1250 m water depth are discussed and compared with that of surface sediment from 1280 m water depth (slope). Fluxes for specific organic compound classes have been computed. The fluxes are of the same magnitude as for equatorial North Atlantic trap particulates at comparable water depth, studied by other investigations.

Steranes and triterpanes generated from kerogen pyrolysis in the absence and presence of minerals

Steranes and triterpanes generated from pyrolysis of immature Monterey Formation kerogen in the presence and absence of calcite, illite and montmorillonite reveal results that are both consistent and divergent with published data that reflect the use of these biological markers as maturation indicators. The extent of isomerization of biomarkers generated from pyrolysis of kerogen at 300 degrees C for 2 hours, at C-20 in 14 alpha(H), 17 alpha(H)-steranes, at C-22 in 17 alpha(H),21 beta(H)-hopanes and of 17 beta(H),21 beta(H)-hopanes correspond to early diagenetic stages in rock extracts from sedimentary basins. Isomerization increases with heating time and, after 1000 hours, attains values which correspond to the catagenetic stage in sedimentary basins, or equivalent to that of mature oil. Stepwise pyrolysis of the kerogen indicates faster isomerization rates for steranes and triterpanes in the bitumen than those retained in the kerogen structure, confirming earlier studies. Presence of a mineral matrix can influence the isomerization of steranes and triterpanes considerably. Comparisons with results from kerogen heated alone, for a given maturation stage, show that calcite inhibits, illite catalyzes slightly and montmorillonite has a pronounced catalytic effect on these reactions. This effect results in early isomerization of steranes and hopanes corresponding to the catagenetic stage in the presence of montmorillonite, while kerogen or kerogen with calcite held at the same temperature (300 degrees C) and time (10 hours) only yield isomerized products which correspond to a diagenetic stage. Further, illite and montmorillonite affect various isomerization reactions differently. The fastest reaction is the isomerization at C-20 in 14 alpha(H),17 alpha (H)-steranes followed by that at C-22 in 17 alpha(H),21 beta(H)-hopanes and the slowest is the formation of 14 beta(H),17 beta(H) steranes. These results show that maturation measurements of rock or oil samples from basins which use biological markers have to take into account the mineral matrix effects, which have been largely ignored until present.

Unusual fatty acids in the lipids of steer and human meibomian gland excreta.

An unusual group of high molecular weight ω-hydroxy fatty acids have been identified in the lipids of the meibomian glands of steer and humans. These acids comprise about 10% of all the acids of the steer lipid, are primarily monoenoic, and constitute three homologous series with members ranging from C30 to C36. They could be important in helping to spread other meibomian gland lipids over the tear film.

Pyrolysis of kerogens in the absence and presence of montmorillonite—I. The generation, degradation and isomerization of steranes and triterpanes at 200 and 300°C☆

Abstract The sterane and triterpane biomarker distribution obtained from extracted bitumens and kerogen (PB) pyrolysate bitumens of immature Cretaceous black shale (CBS) and Rocky Mountain coal (RMC) at 200 and 300°C, in the presence and absence of montmorillonite, reveal that the generation (release) of biomarkers was more significant than isomerization at 200°C pyrolysis, whereas isomerization and degradation were most important at 300°C pyrolysis. Montmorillonite has a pronounced catalytic effect on these reactions, i.e. generation, isomerization, and degradation. The ratios of C29 ααα 20 S/S + R steranes and C31 and C32 αβ S/S + R hopanes display reversals with heating time at 200°C pyrolysis, irrespective of the presence or absence of montmorillonite, whereas they increased uniformly with thermal stress at 300°C pyrolysis. The extent of isomerization occurring at chiral centers in ring systems and in acyclic systems are different. It has been confirmed that the isomerization at the C22 and C20 position of the extended αβ hopanes and the ααα steranes respectively are slower than those of the ββ hopanes and the βαα steranes. In the 300°C pyrolysis, the C27 steranes increased relative to C29 steranes with heating time in the pyrolysate of the Rocky Mountain coal kerogen. This phenomenon is more significant in the presence of montmorillonite. The increase may indicate either the formation of secondary C27 steranes or the early loss of C29 steranes relative to C27 steranes. In a sedimentary basin, isomerization probably occurs in the bitumen and kerogen at different rates. These data show that maturation indices may be reversed with depth by using the examples of ααα 20 S/S + R and αβ 22 S/S + R, where the rate of generation of the compounds from kerogen is faster than the rate of isomerization reactions occurring in the bitumen with time and temperature.

Coprostanols in Antarctic marine sediments: A biomarker for marine mammals and not human pollution☆

Abstract The first analysis of sterols in Antarctic marine sediment cores (Bransfield Strait and McMurdo Sound) is reported here. The isolated sterols in the sediments from Bransfield Strait are comprised mainly of dinosterol (4α,23,24-trimethyl-5αcholest-22-en-3β-ol), coprostanol (5β-cholestan-3β-ol) and epicoprostanol (5β-cholestan-3α-ol) and trace amounts of cholesterol (cholest-5-en-3β-ol). The sediment cores of McMurdo Sound also contain small quantities of coprostanols in addition to large amounts of marine sterols. Dinosterol is a known dinoflagellate chemical marker, whereas coprostanols are currently being used as tracers for sewage contamination. However, sterol composition in Antarctic sediments is expected to be atypical of sewage input and probably different from those of temperate and tropical zones. The coprostanols must therefore arise from the feces of marine mammals, most probably whales which use the region for feeding and spawning. Based on the results of this study, caution should be exercised in the use of coprostanol to estimate the amount of sewage-derived organic matter transported away from impacted coastal areas.

Terpenoid hydrocarbons in Hula peat: Structure and origins☆

Abstract Tri- and tetracyclic diterpenoid and pentacyclic triterpenoid hydrocarbons have been identified in the lipid extracts of three peat samples from the Hula Basin, Israel. Tentative structures for the diterpenoids have been proposed based on mass spectral studies and on extrapolation of known mass spectral fragmentation patterns of most probable biological precursors. The identification of ent-kaurenes in one peat sample appears to be a unique observation. Kaurenes most likely originated from higher plant resins. The triterpenoids in the three samples consist mainly of 17β-hopanes and hopenes, derived from recent biogenic activity. The preponderance of the 17β(H)-hopanes indicates the geological immaturity of the samples and implies that they have undergone only a mild thermal history.

Triterpenols from sediments of Santa Monica Basin, Southern California Bight, U.S.A.☆

The triterpenol geochemistry of the Santa Monica Basin from the Southern California Borderland, off the U.S.A., is described from the study of two sets of trap deployments, five box cores (≈30 cm) and a hydroplastic core (≈1 m). The biogenic sources and diagenetic stability of the triterpenols are discussed. The 17β(H), 21β(H)-hopanols (22R isomer) occur in the carbon number range from 30 to 32 and their abundance is nearly uniform in the shallow sediment sections. However, the three hopanols follow the order of abundance, C32 > C31 ≅ C30, in deeper sections. Their concentrations spans from trace levels to 156 μg/g organic carbon (<15 ng to 7 μg/g dry sediment). Tetrahymanol (gammaceran-3β-ol) has been identified in all the samples except in one set of trap particles collected at 100 m water depth, from trace level (<1 μg) to 215 μg/g organic carbon (<20 ng to 9 μg/g dry sediment). Diplopterol is also detected in trace amounts in some samples. The triterpenols in the trap material generally increase with the water column depth and decrease with the subbottom depth in the sediment cores. The extended hopanols are either degradation products of polyhydroxybacteriohopanes or are biosynthesized by bacteria. Tetrahymanol is probably the only suggested biological precursor of gammacerane (the reduced counterpart of tetrahymanol), which has been recognized in numerous crude oils and lithified sediments. Although it has been reported earlier from Green River Shale and from a residual Pleistocene lake sediment, tetrahymanol has so far been positively identified from recent marine sediments only in two recent studies. The decreasing content of tetrahymanol in sedimentary depth profiles in the Santa Monica Basin would favor an origin for this compound in the water column or at the sediment surface. The ubiquitous occurrence of this compound throughout the study area suggests that this triterpenol most probably originates from primitive organisms (protozoa, bacteria?), hitherto not identified or, more likely, not yet analyzed for their lipid composition.

The occurrence of long chain α,ω-diols in the lipids of steer and human meibomian glands

A group of long chain α,ω-diols (C29 to C34) has been identified in the lipids of steer and human meibomian gland excreta (meibum). These new lipids were isolated from the steer meibum unsaponifiables. Proof of structure was provided by 1) the column chromatographic behavior and TLC of the diols and their diacetates; 2) GLC on glass capillary columns; 3) fragmentation patterns in GC-MS; 4) NMR data, and 5) ozonolysis studies of the unsaturates. Chain types for the steer sample were 51% straight monoenes, 8.5% straight saturates, 39% iso and anteiso saturates and 1.5% iso and anteiso unsaturates. GC for the human sample gave straight monoenes 83%, straight saturates 8%, and iso plus anteiso saturates 9%. Close correspondence of the α,ω-diol chain lengths and types with meibum ω-hydroxy fatty acids suggests a biochemical precursor relationship.

Vitamin E associated with the lipocalin fraction of human tears.

Ocular surface tissues are exposed to light and the accompanying photooxidative reactions that produce reactive oxygen species. Antioxidants are important to prevent free radical reactions with unsaturated fatty acids in cell membranes. Similarly, the reactive oxygen species may damage the lipids in the lipid layer of the tear film. Tears contain the water soluble antioxidants, ascorbic acid, uric acid, glutathione, and cysteine, that are capable of scavenging reactive oxygen metabolites.1–3 Recent data suggest that, together. ascorbic acid and uric acid account for about 44% of the total ferric reducing antioxidant activity in tears.4 However, α-tocopherol (vitamin E) is quite lipid soluble and a potential antioxidant for the lipid layer of tears.