Hydrocarbons in the Surface Layer of Bottom Sediments in the Northwestern Caspian Sea

The paper presents research results on the concentrations and compositions of aliphatic and polycyclic aromatic hydrocarbons in the surface layer of bottom sediments in the Northwestern Caspian Sea (2014) and compares them to data for sediments of the Middle and Southern Caspian (2012–2013). The seepage of hydrocarbons out of the sediment mass, resulting in abnormally high concentrations of aliphatic hydrocarbons per dry weight (up to 468 μg/g), as well as within the C_org composition (up to 35.2%), is considered the main source of hydrocarbons in sediments in the surveyed area of the Northern Caspian. This is also confirmed by the absence of any correlation between the hydrocarbon and C_org distributions, as well as by the transformed oil composition of high-molecular alkanes. The distribution of markers within polycyclic aromatic hydrocarbons points to a mixed genesis—petrogenic and pyrogenic—with prevalence of the latter. Unlike the shallow-water northern part of the Caspian Sea, the content and composition of hydrocarbons in deep-seated sediments are affected by facial conditions of sedimentation and by matter exchange at the water–bottom interface. Therefore, despite high C_org concentrations (up to 9.9%), sediments in deep-water depressions are characterized by a quite low concentration of aliphatic hydrocarbons (52 μg/g on average; 0.2% of C_org) with prevailing natural allochthonous alkanes.     

The composition and distribution of saturated and aromatic hydrocarbons in nearshore sediments, river sediments, and coastal peat of the Alaskan Beaufort Sea: Implications for detecting anthropogenic hydrocarbon inputs

A 3-year program, to determine spatial and temporal trends in sediment concentrations of hydrocarbons and metals from oil and gas exploration and development activities, was conducted in the US Beaufort Sea. Concentrations of saturated and aromatic hydrocarbons in sediments from the Beaufort Sea were elevated in comparison to non-polluted shelf-sediments from other regions of the US coast. Potential natural sources for hydrocarbons that were examined included riverine sediments and coastal peat. Significant quantities of fossil hydrocarbons characterize the surface sediments from the entire region. Sediment inputs from river discharges appear to account for this observation. The use of source-diagnostic ratios has allowed the differentiation of various sources in an area with high naturally-occurring hydrocarbon concentrations where effects due to oil and gas exploration and development activities may be obscured.     

南海沉积物中的正构烷烃和多环芳烃的分布及来源(英文)

重点研究南海沉积物中烃类化合物的有机地球化学特征,讨论了南海沉积物中有机物质的分布和来源。其中正构烷烃分布在Ｃ１６－Ｃ３３奇偶优势不明显,结合其轻重比值,显示有机质的输入在大部分站位以海洋源为主,在一些站位陆源输入的贡献也比较明显,海源输入中又以藻类等有机碎屑的贡献最大。在南海沉积物中共检出６０余种环芳烃,高环化合物（四环和五环）的总含量明显高于其他组分。一些陆源特征标志物如惹烯、烷基屈等化合物被检出,在大多数样品中都发现有的存在,推测其可能来源应是燃烧产物,而非陆源输入。     

Transport of no. 2 fuel oil between water column,surface microlayer and atmosphere in controlled ecosystems

No. 2 fuel oil hydrocarbons put into the bulk water columns of controlled estuarine ecosystems were found to accumulate in the surface microlayer at the air-water interface. The alkane hydrocarbons were disproportionately enriched in the microlayer compared with the aromatic hydrocarbons. A comparison of hydrocarbon boiling point distributions between bulk water, microlayer and air samples indicated that the oil hydrocarbons underwent extensive weathering by evaporation upon reaching the air-water interface. No evidence was found of increased biodegradation in the microlayer compared with that in the underlying water. A fraction of the high molecular weight alkanes, the least water soluble and least volatile constituents of the oil, appeared to be coated out from the microlayer onto the inner walls of the ecosystems.     

Microbial uncultured community of bottom sediments from the bays of Gydan and Yenisei of the Kara Sea

Using methods of molecular biology (PCR and cloning), we studied the diversity of microorganisms in the surface layers of bottom sediments from the bays of Gydan and Yenisei of the Kara Sea, which have different component composition of the pore water and mineralization level. Representatives of the domains Bacteria and Archaea were identified based on the analysis of the 16S rRNA gene fragment nucleotide sequences. The composition of the community of microorganisms in the bottom sediments changed with the changing salinity gradient of the pore waters. The phylogenetic analysis of the nucleotide sequences showed that the composition of the microbial communities in the southern parts of these bays was affected by fresh-water flows from rivers and streams from the lakes within the catchment area, whereas that in the northern parts was influenced by sea waters. The results indicate the presence of bacteria in the bottom sediments that are capable of using a wide range of substrates as a carbon source including hydrocarbons and organochlorine and aromatic compounds. These data can also indicate the presence of different pollutants in the sediments of these areas and the potential ability of bacteria to degrade chemical compounds that enter the waters and bottom sediments of the Kara Sea.     

A chemical investigation of the transport and fate of petroleum hydrocarbons in littoral and benthic environments: The TSESIS oil spill

The fate of saturated and aromatic hydrocarbons discharged into the coastal Baltic Sea environment from the TSESIS oil spill has been studied in the acute and postacute (one year) phases of the spill. Periodic samples of Mytilus edulis (mussels) from eight littoral zone stations and Macoma balthica from nine soft bottom stations were obtained as well as sediment trap samples and surface sediment samples. Glass capillary gas chromatography and gas chromatographic mass spectrometry were used as the analytical tools to determine saturated and aromatic hydrocarbon composition and concentrations in these samples.Sediment trap samples indicated that sizable quantities of chemically and microbially weathered oil were sedimented, and available for benthic uptake shortly after the spill. After initial uptake of sedimented oil (500 to 1000 μ/g dry weight), Macoma populations appear to have begun slow depuration through the first winter after the spill, but TSESIS oil was again introduced to the benthic stations studied during the following summer. Mytilus populations in the region were severely impacted by the oil. Initial depuration of spilled oil during the first month was rapid and nearly complete at all but the most heavily impacted stations one year after the spill. The post-spill depuration of assimilated hydrocarbons was characterised by a relative retention of alkylated dibenzothiophenes and alkylated phenanthrenes compared to their unsubstituted parent compounds and compared with the entire homologous naphthalene series.These data suggest that petroleum hydrocarbons from the TSESIS spill have become a chronic source of degraded saturated and aromatic hydrocarbons to the soft bottom benthic communities. Petroleum hydrocarbons in the benthic environment from this spill appear to reside in the difficulty sampled and mobile flucculent layer at the sediment/water interface and may affect epifaunal communities for an extended period of time.     

Marine organic geochemistry of the Eastern Mediterranean: 1. Aliphatic and polyaromatic hydrocarbons in Cretan Sea surficial sediments

As part of a lipid biogeochemical study, aliphatic and polyaromatic hydrocarbons were determined in surficial sediments from the Cretan Sea (South Aegean Sea) in the Eastern Mediterranean. Total concentrations of both aliphatic (AHC) and polyaromatic (PAH) hydrocarbons were low (562–5697 and 14.6–158.5 ng/g, respectively) with respect to other coastal sediments worldwide and compare with concentrations found in open sea areas. The composition of AHC was dominated by unresolved complex mixture (UCM) indicating the presence of petroleum-related hydrocarbon inputs as confirmed by the detection of specific α,β-hopanes. PAH consisted mainly of pyrolytic four- to five-ring compounds. UCM and PAH amounts revealed that Cretan Sea receives low supply of anthropogenic material compared to NW Mediterranean. The spatial distributions of AHC and PAH indicated that urban run-off and transport from the continental self are the major input pathway of anthropogenic and biogenic hydrocarbons from terrestrial sources in the near shore area, whereas atmospheric transport might be the significant source of hydrocarbons in the deep area.     

综合风化条件下渤海原油中PAHs 变化特征研究

以渤海某原油作为研究对象进行50 d综合模拟风化实验,探讨了原油中五类PAHs组分的分布情况及其风化规律.结果表明:经过50 d风化,原油中PAHs的分布发生了较大的改变:萘系列化合物损失最为严重,相对浓度的损失达到56.78%;菲系列所占的比例有所提高,二苯并噻吩、屈、芴系列则保持相对稳定,其分布特征变化规律为进一步筛选溢油来源鉴别新诊断比值参数提供了一定的导向性;经风化检验,现有常用6种PAHs诊断比值在风化50 d后稳定性良好,可用于风化溢油的鉴别.     

The concentration and composition of hydrocarbons in water,particulate matter,and bottom sediments of the Kara Sea

Data are presented on the content of aliphatic and polycyclic aromatic hydrocarbons (AHC and PAH, respectively) in the interstitial waters and bottom sediments of the Kara Sea compared to the distribution of the particulate matter and organic carbon. It was found that the AHC concentrations within the water mass (16 μg/l on average) are mainly formed by natural processes. The AHC distribution represents the variability of the hydrological and sedimentation processes in different regions of the sea. The widest ranges of the concentrations were registered in the Ob Bay-Kara Sea section: in the water (10–310 μg/l for the AHC and 0.4–7.2 ng/l for the PAH) and in the surface layer of the bottom sediments (8–42 μg/l for the AHC and 9–94 ng/g for the PAH). The differentiation of the hydrocarbons (HC) in the different media follows the marginal filter’s regularities; therefore, no oil and pyrogenic compounds are supplied to the open parts of the sea. In the sediment mass, the HC content is determined by the variations in the oxidative conditions in the sediment and its material’s composition.     

The widespread occurrence of highly branched acyclic C20, C25 and C30 hydrocarbons in recent sediments and biota—A review

The occurrence of widely distributed acyclic isoprenoid hydrocarbons (C_2O, C₂₅ and C₃₀) with highly branched structures, in sediments and biota is reviewed. The compounds occur as alkanes and alkenes with from one to at least four double bonds in young aquatic (both marine and lacustrine) sediments from many parts of the globe (e.g. Peru, Antarctica, Gulf of Suez, North Sea, Atlantic) sometimes in high concentrations (e.g. 40 μg g⁻¹ sediment) relative to other hydrocarbons. However, the compounds rapidly disappear in older sediments, possibly due to biodegradation and reaction with sedimentary sulphur. These and other factors are discussed.The sources of this fascinating group of hydrocarbons remain largely unknown, though evidence points to algae (possibly diatoms) as one possibility. The recent identification of related sulphur-containing compounds in a crude oil promises to extend the number of reports of these compounds still further, and to increase their importance as environmental biological markers.     

The effects of oil exploration and production in the northern North Sea: Part 2—microbial biodegradation of hydrocarbons in water and sediments, 1978–1981

The potential of heterotrophs to degrade aromatic hydrocarbons derived from oil in water and sediments in the northern North Sea around the Brent, Beryl, Forties and Murchison oilfields and at a number of stations, from the Forties field to the Firth of Forth, was estimated using 1-¹⁴C naphthalene and 7, 10-¹⁴C benzo(a)pyrene. The degradation of uniformly labelled ¹⁴C mixed 1-amino acids was used as a measure of total heterotrophic activity. Results showed that microorganisms have the potential to degrade the smaller aromatic hydrocarbon molecules rapidly in the water column and in surface sediments. Close to the Beryl platform, where diesel-washed drill cuttings have been continuously dumped, the rate of input of hydrocarbons to the sediment has exceeded the rate of degradation. Mineralization of benzo(a)pyrene, estimated in the sediments only, was minimal. Close to production platforms the biodegradation rate of mixed 1-amino acids showed no increase comparable with that found for naphthalene, suggesting that existing microbial populations had not increased but adapted to degrade oil in water and sediments.     

Hydrocarbons in the sediments of Port Valdez,Alaska: Consequences of five years' permitted discharge

Hydrocarbons have been investigated in the sediments of Port Valdez, Alaska after three to five years of oil terminal operation with a routine daily discharge of 170 kg of petroleum residue in an otherwise undeveloped area. Surficial benthic sediments (0–5 cm) and core segments down to 30 cm have been analyzed. Information about total hydrocarbons, unresolved complex mixture, normal alkanes, pristane, phytane, hopanes and polycyclic aromatic hydrocarbons indicates that petroleum, biogenic hydrocarbons, and combustion-derived aromatic hydrocarbons are present in sediments around the terminal at concentrations up to 218 μg g^?1 dry sediment. The vertical, horizontal and temporal distributions of anthropogenic hydrocarbons indicate that most of the sedimentary hydrocarbon accumulation has occurred within 1 km of the terminal. A simple calculation suggests that less than 3% of the total oil discharged during routine operations of the terminal has entered the sediments of Port Valdez. For comparison sediment hydrocarbon accumulation associated with a nearby small boat harbor was also examined.     

The effects of oil exploration and production in the northern north sea: Part 1–The levels of hydrocarbons in water and sediments in selected areas, 1978–1981

In the light of increasing oil exploration and production in the northern North Sea, the Brent, Beryl and Forties oil fields, representing three different types of operation, and a number of stations between the Forties field and the Firth of Forth, were sampled to determine the levels of total (by fluorescence), alkane (by glass capillary gas chromatography) and aromatic (by gas chromatography-mass spectrometry) hydrocarbons in water and sediments. Close to the Beryl platform, where diesel-washed drill cuttings have been dumped, there was an accumulation of petrogenic hydrocarbons in the sediment, resulting in a build up of certain aryl hydrocarbons, notably the dibenzthiophenes and 3- and 4-ring aromatic compounds. In all the sediment samples analysed for aromatic hydrocarbons, relatively large amounts of 5- and 6-ring compounds were found in areas expected to be free of pollution, as well as from areas around oil platforms and from the Firth of Forth. Their source is likely to be windborne combustion products.     

Candidate biomarker discovery in plasma of juvenile cod (Gadus morhua) exposed to crude North Sea oil, alkyl phenols and polycyclic aromatic hydrocarbons (PAHs)

In this study we have investigated protein changes in plasma of juvenile Atlantic cod (Gadus morhua) induced by crude North Sea oil and North Sea oil spiked with alkyl phenols and polycyclic aromatic hydrocarbons, a surrogate produced water composition. Using a proteomic approach, we identified 137 differentially expressed proteins at different levels of crude oil exposure. Many of the induced protein changes occurred at low levels of exposure. The results obtained with protein expression profiles after exposure to oil and surrogate produced water indicate effects on fibrinolysis and the complement cascade, the immune system, fertility-linked proteins, bone resorption, fatty acid metabolism as well as increased oxidative stress, impaired cell mobility and increased levels of proteins associated with apoptosis. Although the number of individuals and samples in this study is limited within each treatment group, the protein changes observed in this study represent a first screening for potential biomarker candidates in cod plasma reflecting potential effects of crude oil and produced water exposure on fish.     

Hydrocarbon pollution from marinas in estuarine sediments

A measure of the impact of marinas on three Eastern Virginia estuarine creeks was obtained by a study of hydrocarbons in their sediments. Two of the creeks support considerable marine activity, including pleasure boat marinas, boat repair facilities, and commercial fishing operations. The third creek, which served as a control, is seldom used by boats, and is surrounded by marsh and woodland.Sediments from the creeks with marinas contained significantly higher levels of both aromatic and aliphatic hydrocarbons than did the control. Differences in the concentrations of certain oil-pollution indicators, such as the 17α,21β-hopane homologs and phytane, and low molecular weight aromatic hydrocarbons, are indicative of light petroleum fractions. Most of the aromatic hydrocarbons from all creeks, however, appear to have a pyrogenic origin.Although hydrocarbons from three probable origins (petroleum, pyrogenesis, and recent biosynthesis) were detected in all locations, the petroleum-derived and pyrogenic hydrocarbons were of only minor importance relative to the biogenic hydrocarbons in the control creek.     

Persistence of oiling in mussel beds after the Exxon Valdez oil spill

Persistence and weathering of Exxon Valdez oil in intertidal mussel (Mytilus trossulus) beds in Prince William Sound (PWS) and along the Gulf of Alaska was monitored from 1992 to 1995. Beds with significant contamination included most previously oiled areas in PWS, particularly within the Knight Island group and the Kenai Peninsula. In sediments, yearly mean concentrations of total petroleum hydrocarbons ranged from < 60 micrograms/g in reference beds to 62,258 micrograms/g wet wt., or approximately 0 to 523 micrograms/g dry wt. total polynuclear aromatic hydrocarbons (TPAHs). In mussels, mean TPAH concentrations ranged up to 8.1 micrograms/g dry wt. Hydrocarbon concentrations declined significantly with time in some, but not all mussels and sediments, and should reach background levels within three decades of the spill in most beds. In 1995, mean hydrocarbon concentration was greater than twice background concentration in sediments from 27 of 34 sites, and in mussels from 18 of 31 sites.     

Hydrocarbons in Washington coastal sediments

The sources and distributions of polycyclic aromatic hydrocarbons (PAH) and aliphatic hydrocarbons are characterized in seventeen sediments from a highly river-influenced sedimentary environment off the southwestern coast of Washington. The major hydrocarbons are land-derived, introduced as preformed compounds and display long-term stability in sediment cores. A series of PAH of anthropogenic origin and two naturally derived compounds, retene and perylene, dominate the PAH composition in these sediments. Plantwax n-alkanes are the major aliphatic hydrocarbon constituents. Aliphatic hydrocarbons of marine origin, pristane and a series of four acyclic, multibranched C₂₅ polyolefins, are also observed in many sediments. The concentrations of these marine-derived hydrocarbons decrease to negligible levels rapidly with sediment depth from the sea-sediment interface, suggesting degradation.In general, the major land-derived hydrocarbons are concentrated in the midshelf silt deposit which extends northwestward along the continental shelf from the Columbia River mouth. A quantitatively more minor, natural series of phenanthrene homologs, also of terrestrial origin, is preferentially advected further offshore and deposited in continental slope sediments. These distributions are consistent with recognized particle associations for these compounds and sediment dispersal processes in this coastal environment. Sediment core records suggest the present pattern of dispersal has persisted for at least the past century and possibly since the Late Pleistocene.     

Chemical and biological assessment of two offshore drilling sites in the Alaskan Arctic

A retrospective chemical and biological study was carried out in Camden Bay, Alaskan Beaufort Sea, where single exploratory oil wells were drilled at two sites more than two decades ago. Barium from discharged drilling mud was present in sediments at concentrations as high as 14%, ∼200 times above background, with significantly higher concentrations of Ba, but not other metals, within 250 m of the drilling site versus reference stations. Elevated concentrations of Cr, Cu, Hg and Pb were found only at two stations within 25 m of one drilling site. Concentrations of total polycyclic aromatic hydrocarbons (TPAH) were not significantly different at reference versus drilling-site stations; however, TPAH were elevated in Ba-rich layers from naturally occurring perylene in ancient formation cuttings. Infaunal biomass and species abundance were not significantly different at reference versus drilling-site stations; infauna were less diverse at drilling-site stations. Our assessment showed that discharges from single wells within large areas caused minimal long-term, adverse impacts to the benthic ecosystem.     

Triterpenoids as molecular indicators of paleoseepage in recent sediments of the Southern California bight

Petroleum-derived hydrocarbons have been identified in sediments by analysis of the n-alkanes, aromatic hydrocarbons and branched and cyclic components (humps). The detection of low levels of petroleum input to sediments can be ambiguous due to the presence of syngenetic biolipids. Triterpenoids, especially the (17αH, 21βH)-hopanes, have been proposed as sensitive molecular markers of petroleum pollution.Recent sediments from the Southern California Bight to subbottom depths of about 30 cm (pre-anthropogenic) contain lipids of syngenetic origin with major humps of branched and cyclic material and triterpenoids consisting mainly of the (17αH, 21βH)-hopanes ranging from C₂₇ to C₃₅. Extended hopanes (> C₃₁) are found as 1:1 mixtures of the 22R and 22S diastereomers. The 17α(H),18α(H), 21β(H)-28,30-bisnorhopane is the dominant triterpane for most of these sediments and appears to be a potential molecular marker characteristic of the Southern California petroleums. Extended tricyclic diterpanes ranging from C₁₉ to C₂₇ are also present and their structures make them further possible indicators of petroleum. Southern California Bight sediments therefore appear to contain petroleum products from both seepage and anthropogenic activity.Recent sediments from other areas (e.g. Guaymas Basin, Gulf of California; Cook Inlet, Alaska; Eastern Bering Sea; Walvis Bay, Southwest Africa; and Mangrove Lake, Bermuda) contain predominantly (17βH, 21βH)-hopanes and hopenes, indicating recent synthesis and no petroleum pollution.     

Natural background and anthropogenic inputs of polycyclic aromatic hydrocarbons (PAH) in sediments of South-Western Barents Sea

Polycyclic aromatic hydrocarbons (PAH) were measured in sediment cores from 13 locations in South-Western Barents Sea as part of a detailed study of the Norwegian seabed under the MAREANO program. The generally low PAH levels found, an average around 200 ng g⁻¹ dry weight for sum PAH, indicate low inputs of petroleum hydrocarbons to the marine environment in the area. Differences in PAH composition and various PAH ratios indicate a natural, mostly petrogenic origin of PAH in sediments from the open sea locations, while the fjord locations show higher pyrogenic PAH contents with an increase towards upper sediment layers, indicating low inputs from human activities. Petrogenic PAH levels increase in deeper sediments at open sea locations, also when normalised to total organic carbon (TOC) contents, suggesting natural leakages of oil-related hydrocarbons in the area.