Sulfate reduction below the sulfate-methane transition in Black Sea sediments

A sudden increase in salinity about 7000 years ago caused a shift in the deposited sediments of the Black Sea from limnic to brackish-marine. Due to the development of an anoxic deep water basin and a relatively high sulfate concentration, organic matter is mineralized primarily through sulfate reduction in modern Black Sea sediments. Earlier studies showed that sulfate-reducing bacteria are abundant within the limnic sub-surface sediment in spite of extremely low concentrations of sulfate and organic carbon. A main objective of the present study was therefore to understand the depth distribution of sulfate reduction across the different sediment units, even deep below the sulfate-methane transition. Our study combined experimental measurements of sulfate reduction using ³⁵S radiotracer with analyses of sulfur and iron geochemistry in pore water and sediment. Potential sulfate reduction rates were measured with ³⁵S in sediment samples that were amended with sulfate and organic substrates and incubated in time-series up to 48 h. Sulfate reduction could thereby be detected and quantified at depths where concentrations of sulfate were otherwise too low to enable calculation of the rates. The results demonstrate that sulfate-reducing bacteria are active several meters below the sulfate-methane transition in Black Sea sediments. The cryptic sulfate reduction below the sulfate-methane transition may be driven by sulfate produced from re-oxidation of reduced sulfur species with oxidized iron minerals buried in the deep limnic sediment.     

九龙江河口沉积物中硫酸盐还原与甲烷厌氧氧化:同位素地球化学证据

通过沉积物柱孔隙水中甲烷,SO2-4,Cl-,δc(34S-SO2-4)、δc(13 C-CH4)的垂直分布特征,研究了硫酸盐还原和甲烷厌氧氧化(anaerobic oxidation of methane,简称AOM)过程在九龙江河口沉积物中的分布规律.测定结果显示两个站位(J-A和J-E)间隙水中SO2-4浓度随深...     

Molecular signals for anaerobic methane oxidation in Black Sea seep carbonates and a microbial mat

Linked to gas seeps on the Ukrainian shelf (northwestern Black Sea), massive authigenic carbonates form as a result of anaerobic methane oxidation. Lipid distributions in these ‘cold seep’ carbonates and an associated microbial mat were investigated for process markers reflecting the presence and metabolic activity of distinctive methane-related biota. The samples contain free, irregular isoprenoid hydrocarbons, namely the tail-to-tail linked acyclic C₂₀-isoprenoid 2,6,11,15-tetramethylhexadecane (crocetane), its C₂₅-homologue 2,6,10,15,19-pentamethylicosane (PMI), and several unsaturated derivatives thereof. Furthermore, specific acyclic and cyclic C₄₀-isoprenoids were released upon ether cleavage of the polar fraction from the carbonate. The abundance of these compounds indicates a pronounced role of particular Archaea in the biogeochemical cycling of carbon at methane seeps. Stable carbon isotopic analyses of these lipids reveal extraordinary depletions in ¹³C corresponding to δ-values in the range of −100±30‰ PDB, whereas other compounds show isotopic compositions normally observed for marine lipids (around −30‰ PDB). The isotope data imply that the biosynthesis of the archaeal isoprenoids occurred in situ and involved the utilization of isotopically depleted, i.e. methane-derived, carbon. Apart from archaeal markers, the carbonate and the mat contain authigenic, framboidal pyrite and isotopically depleted fatty acids, namely iso-, and anteiso-branched compounds most likely derived from sulphate-reducing bacteria (SRB). The indications for a tight association of these normally competitive organisms support a model invoking a syntrophic relationship of SRB with Archaea responsible for the anaerobic oxidation of methane. The biomarker patterns obtained from the Black Sea samples were further compared to those from a Oligocene seep carbonate (Lincoln Creek Formation, WA, USA) in order to evaluate their biomarker potential for ancient settings. The prominent occurrence of isotopically light crocetane (−112‰) and PMI (−120‰) meets the findings for the contemporary materials. Thus, isotopically depleted isoprenoids provide diagenetically stable fingerprints for the reconstruction of carbon cycling in both, modern and ancient methane seep systems.     

海洋沉积物中金属依赖型甲烷厌氧氧化作用研究进展及展望

海洋沉积物中大部分甲烷会通过甲烷厌氧氧化作用（anaerobic oxidation of methane, AOM）而被消耗。早期研究表明,AOM可与硫酸盐、硝酸盐和亚硝酸盐的还原作用相耦合,从而有效减少甲烷向大气的排放。最近,金属依赖型AOM（metal-AOM,活性金属氧化物还原反应驱动的AOM）被证实存在于自然界沉积物和富集培养的样品中。但是,目前仍未从自然海洋环境中分离获得能够介导metal-AOM的微生物。对海洋沉积物中metal-AOM的研究大多聚焦于热液或冷泉等海洋特殊生境,一系列研究表明地质流体在这些海底化能自养生态系统的维持和演化方面起到了重要作用,并深刻影响全球地球化学循环,因此,该科学问题研究吸引了越来越多的注意力。本文讨论了可能参与海洋沉积物中metal-AOM的微生物类群及其地球化学证据,并在前人工作基础上,以冲绳海槽冷泉-热液共生区为例,提出一种新的metal-AOM作用机制。认为在全球冷泉-热液系统相互作用地区的调查有助于更好地探讨metal-AOM的发生机制及微生物在深海生境中分布的连通性问题。     

Sulfate reduction and sulfide deposition in deep-sea sediments from the southwestern Japan Sea

Vertical profiles of total sulfur and organic carbon have been measured in two deep-sea piston cores from the southwestern Japan Sea where sulfate reduction is proceeding within the sediments. The content of total sulfur, most of which is present as pyrite, increases gradually with increasing depth, showing several peaks. The amount of diagenetically deposited sulfide-sulfur is estimated using a steady-state model that considers vertical change in the diffusion coefficient. It is suggested that two-thirds to three-fourths of the observed total sulfur content has been deposited diagenetically.     

Sulfate reduction in Black Sea sediments: in situ and laboratory radiotracer measurements from the shelf to 2000 m depth

Sulfate reduction rate measurements by the ³⁵SO₄²⁻ core injection method were carried out in situ with a benthic lander, LUISE, and in parallel by shipboard incubations in sediments of the Black Sea. Eight stations were studied along a transect from the Romanian shelf to the deep western anoxic basin. The highest rates measured on an areal basis for the upper 0–15 cm were 1.97 mmol m⁻² d⁻¹ on the shelf and 1.54 mmol m⁻² d⁻¹ at 181 m water depth just below the chemocline. At all stations sulfate reduction rates decreased to values <3 nmol cm⁻³ d⁻¹ below 15 cm depth in the sediment. The importance of sulfate reduction relative to the total mineralization of organic matter was very low, 6%, on the inner shelf, which was paved with mussels, and increased to 47% on the outer shelf at 100 m depth. Where the oxic–anoxic interface of the water column impinged on the sea floor at around 150 m depth, the contribution of sulfate reduction increased from >50% just above the chemocline to 100% just below. In the deep sea, mean sulfate reduction rates were 0.6 mmol m⁻² d⁻¹ corresponding to an organic carbon oxidation of 1.3 mmol m⁻² d⁻¹. This is close to the mean sedimentation rate of organic carbon over the year in the western basin. A comparison with published data on sulfate reduction in Black Sea sediments showed that the present results tend to be higher in shelf sediments and lower in the deep-sea than most other data. Based on the present water column H₂S inventory and the H₂S flux out of the sediment, the calculated turnover time of H₂S below the chemocline is 2100 years.     

南海东沙东北部甲烷缺氧氧化作用的生物标志化合物及其碳同位素组成

南海东沙东北部碳酸盐岩和泥质沉积物中的生物标志化合物组合及其碳同位素组成分析表明,研究区内甲烷缺氧氧化作用(anaerobic oxidation of methane-AOM)发育.研究区内碳酸盐岩中含丰富的AOM标志化合物,2,6,11,15-四甲基十六烷(Crocetane-Cr.)、2,6,10,15,19-五甲基番茄烷(Pentamethylicosane-PMI)和2,6,10,15,19,23-六甲基二十四烷(Squalane-Sq角鲨烷)的13C亏损强烈(δ13C值介于-74.2‰~-119.0‰PDB之间),表明碳酸盐岩形成于AOM,同时反映该研究区曾发生过强烈、持续的富CH₄流体释放活动.柱状泥质沉积物中,AOM生物标志化合物在硫酸岩-甲烷过渡带(SMI-Sulfate-Methane Interface)边界附近相对丰度高,SMI之上样品中含量低,或未检出,表明现代环境在SMI附近有大量嗜甲烷微生物生长,使得深部上升的甲烷被大量消耗,很少有甲烷逸出海底.AOM生物标志化合物可用来指示SMI边界.不同站位、不同岩性AOM生物标志化合物组成(包括碳同位素组成)的差异反映了嗜甲烷古细菌组成的不同.     

Sulfate reduction in deep coastal marine sediments

Sulfate reduction rates in sediments of four deep stations in the Saguenay Fjord and the Laurentian Trough, Gulf of St. Lawrence, are among the lowest reported for the coastal environment. Maximum rates were 0.4–7.0 nmol cm⁻³ day⁻¹. The low rates are due to relatively low sedimentation rates and continuously low temperatures. Regional differences in both integrated and maximum sulfate reduction rates in the sediment correlate with sediment trap measurements of sedimentation rate and organic carbon flux.Sulfate reduction accounts for the degradation of 5–26% of the estimated downward flux of organic matter to these sediments. Unlike the absolute rate of sulfate reduction, the relative proportion of the carbon flux that is degraded via sulfate reduction is not directly correlated with the sedimentation rate but is a function of organic matter composition, intensity of bioturbation, and the abundance of sub-oxic electron acceptors. Thus, the lowest proportion of carbon degradation via sulfate reduction occurred at a Gulf site, where a combination of low sedimentation and bioturbation rates allowed a long residence time for organic matter near the sediment surface and, in consequence, a low flux of labile carbon into the sulfate reduction zone. The highest proportion was observed at a station with a similar organic carbon flux but with higher rates of sedimentation and bioturbation. At a third site, with the highest rates of sulfate reduction as well as the highest rates of sedimentation and bioturbation, the contribution of sulfate reduction to organic matter degradation was only intermediate. This is attributable to the exhaustion of the supply of porewater sulfate. In deep coastal environments the proportion of organic matter degraded via sulfate reduction can be highly variable both spatially and temporally.     

深海冷泉古菌厌氧甲烷氧化研究进展

在富含甲烷水合物的海相冷泉沉积物中, 古菌厌氧甲烷氧化作用(anaerobic oxidation of methane, AOM)越来越受到人们的重视。目前普遍认为, AOM是由嗜甲烷古菌和硫酸盐还原菌共同调节的生物地球化学过程。16S rRNA基因分析表明, 包括AEME-1、AEME-2和AEME-3在内的多种甲烷古菌参与了AOM的过程, 它们广泛分布于全球大洋海底缺氧带。AOM过程与全球环境变化密切相关, 从深海底部冷泉区向上渗漏的甲烷气体, 绝大部分在穿透缺氧带沉积层过程中被甲烷氧化古菌所消耗, 有效减少了具有强烈温室效应的甲烷气体向大气的释放。对AOM生物地球化学过程的研究, 在认识冷泉系统碳酸盐的形成机理、控制强温室气体甲烷从海底的渗漏和开发可燃冰新能源等方面具有重要意义。     

Lipid biomarkers for anaerobic oxidation of methane and sulphate reduction in cold seep sediments of Nyegga pockmarks (Norwegian margin): discrepancies in contents and carbon isotope signatures

Distributions and carbon isotopic compositions of microbial lipid biomarkers were investigated in sediment cores from the G11 and G12 pockmarks in the Nyegga sector of the Storegga Slide on the mid-Norwegian margin to explore differences in depth zonation, type and carbon assimilation mode of anaerobic methane-oxidizing archaea (ANMEs) and associated sulphate-reducing bacteria responsible for anaerobic oxidation of methane (AOM) in these cold seep environments. While the G11 site is characterised by black reduced sediments colonized by gastropods and Siboglinidae tubeworms, the G12 site has black reduced sediments devoid of fauna but surrounded by a peripheral occurrence of gastropods and white filamentous microbial mats. At both sites, bulk sediments contained abundant archaeal and bacterial lipid biomarkers substantially depleted in ¹³C, consisting mainly of isoprenoidal hydrocarbons and dialkyl glycerol diethers, fatty acids and non-isoprenoidal monoalkylglycerol ethers. At the G11 site, down-core profiles revealed that lipid biomarkers were in maximum abundance from 10 cm depth to the core bottom at 16 cm depth, associated with δ¹³C values of ?57 to ?136‰. At the G12 site, by contrast, lipid biomarkers were in high abundance in the upper 5 cm sediment layer, associated with δ¹³C values of ?43 to ?133‰. This suggests that, as expected from the benthic fauna characteristics of the sites, AOM takes place mainly at depth in the G11 pockmark but just below the seafloor in the G12 pockmark. These patterns can be explained largely by variable fluid flow rates. Furthermore, at both sites, a dominance of ANME-2 archaea accompanied by their bacterial partners is inferred based on lipid biomarker distributions and carbon isotope signatures, which is in agreement with recently published DNA analyses for the G11 pockmark. However, the present data reveal high discrepancies in the contents and δ¹³C values for both archaeal and bacterial lipid profiles, implying the possible involvement of at least two distinct AOM-related microbial consortia at the inferred AOM depth zonation of G11 and G12 pockmark sediments. In both sediment cores, the δ¹³C profiles for most archaeal lipids suggest a direct assimilation of dissolved inorganic carbon (DIC) in addition to methane by ANMEs (chemoautotrophy); constant and highly depleted δ¹³C profiles for PMI:3, an archaeal lipid biomarker presumably related to ANME-2, suggest a direct assimilation of ¹³C-depleted methane-derived carbon via AOM (methanotrophy). Evidently, the common approach of investigating lipid biomarker contents and δ¹³C signatures in cold seep sediments does not suffice to precisely discriminate between the carbon assimilation mode for each ANME archaeal group and associated bacteria. Rather, this needs to be combined with further specific labelling studies including different carbon sources (methane carbon, methane-derived organic intermediates and DIC) in order to unravel the metabolic pathways of each microbial consortium involved in AOM (ANME-1 vs. ANME-2 vs. ANME-3 archaeal group and associated bacteria).     

Geochemical peculiarities of sediments in the northeastern Black Sea

We present the results of chemical determinations of Al, Fe, Mn, Cu, Ni, Co, Cr, Pb, Sb, and As in Black Sea sediments over a profile from the Kerch Strait to the eastern part of a deep depression (2210 m). The lithological and geochemical variations were studied in the horizontal and vertical profiles of sediments up to 3 m thick. The tendencies in the distributions of the studied metals during Pleistocene and Holocene sedimentation were analyzed beginning from Neoeuxinian freshwater deposits via the overlaying Drevnechernomorian beds with elevated contents of sapropel to modern clayey carbonate deposits with coccolithophorids. Statistical factor analysis isolated five factors: two main factors (75% of the total dispersion) and three subordinate factors. The first leading biogenic factor (47% of dispersion) reflects the correlation between С_org, Cu, and Ni; the second terrigenous factor (28% of dispersion) combimes Fe, Al, Cr, and Sb. The chemical composition of the sediments reflects the manifestation of diagenesis of landslide processes and mud volcanism along with sedimentation regularities.     

The influence of coupling mode of methane leakage and debris input on anaerobic oxidation of methane

Anaerobic oxidation of methane(AOM) is an important biogeochemical process, which has important scientific significance for global climate change and atmospheric evolution. This research examined the δ~(34)S, terrigenous clastic indices of TiO_2 and Al_2O_3, and times for formation of the Ba front at site SH1, site SH3 and site 973-4 in the South China Sea. Three different coupling mechanisms of deposition rate and methane flux were discovered. The different coupling mechanisms had different effects on the role of AOM. At site 973-4, a high deposition rate caused a rapid vertical downward migration of the sulphate–methane transition zone(SMTZ), and the higher input resulted in mineral dissolution. At site SH3, the deposition rate and methane flux were basically in balance,so the SMTZ and paleo-SMTZ were the most stable of any site, and these were in a slow process of migration. At site SH1, the methane flux dominated the coupled mode, so the movement of the SMTZ at site SH1 was consistent with the general understanding. Understanding the factors influencing the SMTZ is important for understanding the early diagenesis process.     

Diverse methane concentrations in anoxic brines and underlying sediments,eastern Mediterranean Sea

Elevated methane (CH₄) concentrations (128–2692×10³ nM) occur in the hypersaline anoxic brine pools of Bannock and Urania Basins, eastern Mediterranean Sea, compared to low concentrations (17–80×10³ nM) in the sediments below the anoxic brines. The CH₄ enrichment in the brines might be due to the long residence time of the brine in the Basin. An attempt is made to determine the sources for the enriched dissolved CH₄ by considering the influence of hydrothermal activity, the occurrence of sapropel layers (biogenic) and dissolution of gas hydrates. Furthermore, it is suggested that the enriched CH₄ in Bannock and Urania Basins is diffused and mixed with the overlying waters by local upward transport mechanisms that selectively move CH₄ upward in these Basins.     

Meiobenthos from an active methane seepage area in the NW Black Sea

Meiobenthos densities and higher taxon composition were studied in an active gas seepage area at depths from 182 to 252 m in the submarine Dnieper Canyon located in the northwestern part of the Black Sea. The meiobenthos was represented by Ciliata, Foraminifera, Nematoda, Polychaeta, Bivalvia, Gastropoda, Amphipoda, and Acarina. Also present in the sediment samples were juvenile stages of Copepoda and Cladocera which may be of planktonic origin. Nematoda and Foraminifera were the dominant groups. The abundance of the meiobenthos varied between 2397 and 52,593 ind.·m⁻². Maximum densities of Nematoda and Foraminifera were recorded in the upper sediment layer of a permanent H₂S zone at depths from 220 to 250 m. This dense concentration of meiobenthos was found in an area where intense methane seeps were covered by methane‐oxidizing microbial mats. Results suggest that methane and its microbial oxidation products are the factors responsible for the presence of a highly sulfidic and biologically productive zone characterized by specially adapted benthic groups. At the same time, an inverse correlation was found between meiofauna densities and methane concentrations in the uppermost sediment layers. The hypothesis is that the concentration of Nematoda and Foraminifera within the areas enriched with methane is an ecological compromise between the food requirements of these organisms and their adaptations to the toxic H₂S.     

Investigation of the biogeochemistry of methane and mechanisms of its transfer in the Black Sea

We demonstrate the importance of investigation of the behavior of methane as a source of energy and an element of the Black-Sea ecosystem affecting the global behavior of the climate. We describe the genesis of methane and the processes of its aerobic and anaerobic oxidation. An especially important biogeochemical and ecological role is played by the anaerobic oxidation of methane guaranteeing the formation of its effective sink inside the anaerobic zone and preventing its penetration into the atmosphere as a greenhouse gas. On the basis of the analysis of the experimental data available from the literature, we also discuss the principal regularities of the distribution of concentration of methane and its flows. It is shown that the formation of methane hydrates at the bottom in the abyssal part of the Black Sea and the events of jet gas release on the periphery of the basin can be regarded as the components of a single global process of gas release from the bottom of the Black Sea. We present estimates of the components of methane budget in the Black Sea. The results of simulation of the dynamics of methane bubbles and the processes of their gas exchange with the medium are analyzed. The data of hydroacoustic measurements are used to evaluate the distribution of methane bubbles in sizes and the mass transfer of methane through the ocean–atmosphere interface. Finally, we consider the methods of mathematical simulation of the distribution of methane in the ecosystem of the Black Sea. Translated from Morskoi Gidrofizicheskii Zhurnal, No. 5, pp. 40–56, September–October, 2008.     

Parameters of the sediments of the deep-water basin of the Black Sea

The methodology and the first results of the computations of the volumes, masses, and growth rates of the sedimentary body of the buried Black Sea basin are presented. Their temporal evolution reflects the regional paleogeodynamics, in particular, the reorientation of the vector of the relative movement of the Arabian and Eurasian lithospheric plates and the related intensification of their collision in the late Miocene-Pliocene.     

Sulfur and iron speciation in surface sediments along the northwestern margin of the Black Sea

The speciation of sedimentary sulfur (pyrite, acid volatile sulfides (AVS), S⁰, H₂S, and sulfate) was analyzed in surface sediments recovered at different water depths from the northwestern margin of the Black Sea. Additionally, dissolved and dithionite-extractable iron were quantified, and the sulfur isotope ratios in pyrite were measured. Sulfur and iron cycling in surface sediments of the northwestern part of the Black Sea is largely influenced by (1) organic matter supply to the sediment, (2) availability of reactive iron compounds and (3) oxygen concentrations in the bottom waters. Biologically active, accumulating sediments just in front of the river deltas were characterized by high AVS contents and a fast depletion of sulfate concentration with depth, most likely due to high sulfate reduction rates (SRR). The δ³⁴S values of pyrite in these sediments were relatively heavy (−8‰ to −21‰ vs. V-CDT). On the central shelf, where benthic mineralization rates are lower, re-oxidation processes may become more important and result in pyrite extremely depleted in δ³⁴S (−39‰ to −46‰ vs. V-CDT). A high variability in δ³⁴S values of pyrite in sediments from the shelf-edge (−6‰ to −46‰ vs. V-CDT) reflects characteristic fluctuations in the oxygen concentrations of bottom waters or varying sediment accumulation rates. During periods of oxic conditions or low sediment accumulation rates, re-oxidation processes became important resulting in low AVS concentrations and light δ³⁴S values. Anoxic conditions in the bottom waters overlying shelf-edge sediments or periods of high accumulation rates are reflected in enhanced AVS contents and heavier sulfur isotope values. The sulfur and iron contents and the light and uniform pyrite isotopic composition (−37‰ to −39‰ vs. V-CDT) of sediments in the permanently anoxic deep sea (1494 m water depth) reflect the formation of pyrite in the upper part of the sulfidic water column and the anoxic surface sediment. The present study demonstrates that pyrite, which is extremely depleted in ³⁴S, can be found in the Black Sea surface sediments that are positioned both above and below the chemocline, despite differences in biogeochemical and microbial controlling factors.     

Microbially mediated methane and sulfur cycling in pockmark sediments of the Gdansk Basin, Baltic Sea

In the Russian sector of the Gdansk Basin (Baltic Sea), high organic matter influx fuels microbial processes resulting in the formation of reduced sediments with elevated methane concentrations. Investigated areas of geoacoustic anomalies (～245 km²) were found to contain three distinct geomorphologic structures (pockmarks), with a total area of ～1 km². Methane anomalies recorded in the water above one of these pockmarks were traced as high as 10 m above the bottom. In pockmark sediments, sulfate reduction and anaerobic oxidation of methane (AOM) occurred at high rates of 33 and 50 µmol dm^?3 day^?1, respectively. Integrated over 0–180 cm sediment depths, AOM exceeded methanogenesis almost tenfold. High AOM rates resulted from methane influx from deeper sediment layers. The δ¹³C signature of methane carbon (?78.1 to ?71.1‰) indicates the biogenic origin of pockmark methane. In pockmark sediments, up to 70% of reduced sulfur compounds was possibly produced via AOM.     

Arsenic and heavy metals in the bottom sediments of the Balaklava Bay (Black Sea)

We present the results of investigation of the contents of metals (As, Cr, Co, Cu, Ni, Pb, Zn, V, Sr, Mn, Ti, and Fe) in the bottom sediments of the Balaklava Bay (Black Sea) carried out in July 2005. It is shown that the pollution of the bottom sediments with metals has a polyelemental character. We establish the specific features of changes in the contents of the analyzed elements and localize the sources of their appearance in the ecosystem. On the basis of the results of evaluation of the intensity of technogenic action upon the marine medium, we determine a group of toxic elements (As, Cr, Cu, Pb, and Zn) accumulated in the bottom sediments of the bay in amounts significantly exceeding the background values typical of sediments of the Black Sea shelf. The comparative analysis of the degrees of pollution of the bay and some other coastal water areas with metals is performed.     

Mathematical simulation of the distribution of hydrocarbons in the aerobic and anaerobic waters of the Black Sea

We improve and extend the set of parametrizations of chemical and biological processes governing the assimilation of the emulsion-dissolved fraction of hydrocarbons in marine media with regard for the oxidation-reduction conditions in the oxycline and in the aerobic, suboxic, and anaerobic zones of the Black Sea. The numerical experiments aimed the reconstruction of the vertical and spatial distributions of hydrocarbons are performed. The increase in the number of fractions of hydrocarbons from three to five, taking into account the influence of the concentration of oxygen, and the analysis of the processes of anaerobic and photochemical oxidation of hydrocarbons make it possible to construct a numerical model of distribution of hydrocarbons in the aerobic and anaerobic waters of the sea and get good quantitative agreement between the results of numerical experiments and the data of observations. __________ Translated from Morskoi Gidrofizicheskii Zhurnal, No. 6, pp. 53–67, November–December, 2006.