Heavy-mineral variability in bottom sediments of the lower Chesapeake Bay,Virginia

Heavy minerals in bottom-sediment samples of the lower Chesapeake Bay show distribution patterns and interrelationships that denote characteristic mineral suites associated with defined geographic provinces. The Baymouth province has a garnet—hornblende—pyroxene suite, which is largely attributed to the influx of littoral and shelf sediments; the Eastern Shore province has a similar suite, derived largely from coastal erosion of the Eastern Shore peninsula. The Northern and Combined River provinces have a zircon—tourmaline—staurolite assemblage, which reflects derivation from an Appalachian Piedmont—Atlantic Coastal Plain sourceland. The Western Shore province is associated with a zircon—epidote—staurolite assemblage, apparently derived jointly from tributary influx and coastal erosion of the western shore. Factor analysis identified two major factors that account for 63% of the total variation in the relative amounts of the seven most common heavy minerals. The dominant factor (44%) is based on a zircon—hornblende—staurolite—pyroxene relationship, which indicates that mineral stability, as influenced by sediment maturity, is a major contributing factor. The second factor (19%) based on a tourmaline—epidote—staurolite—garnet relationship indicates that provenance is another major cause of heavy-mineral variability within the lower bay.     

Rises of the Amerasia Basin,Arctic Ocean,and Possible Equivalents in the Atlantic Ocean

Oceanology - Abstract—The main positive morphostructures of the Amerasia Basin — the Lomonosov Ridge, Alpha Ridge, Mendeleev Rise, Chukchi Plateau, and Northwind Ridge — are...     

New genera and species of benthic calanoid copepods from the New Zealand slope

Thirteen new species of benthic calanoid copepods are described from depths of 1,184–1,697 m off New Zealand. Seven species belong to previously described aetideid genera (Bradyidius—four spp., Comantenna—one sp., Pseudeuchaeta—two spp.) and the remainder represent new genera in three families: Aetideidae—three genera, four spp.; Arietellidae—one genus and sp.; Bathypontiidae—one genus and sp.     

The tectonics of the Okhotsk Sea

The northern and central parts of the Okhotsk Sea form an epiMesozoic platform. The hetero-aged acoustic basement is represented by deformed geosynclinal rocks from Cretaceous to Precambrian in age. The slightly deformed sedimentary cover levelled the uneven surface of the acoustic basement, and this Upper Paleogene—Neogene cover filled up the system of the structural basins. The general NW—SE and W—E extensions of the taphrogenic horsts and grabens of the acoustic basement were formed due to extension and subsidence of the earth's crust during the late Paleogene—Neogene.     

Deformation of the Submerged Slope of the Anapa Bay-Bar From 2012 to 2018

Oceanology - Abstract—The article considers the long-term relief dynamics of the submerged slope of the Anapa bay-bar. The Anapa bay-bar consists of five morphological elements—Solenoe...     

Influence of diagenesis on the electrical resistivity and the formation factor of deep-sea carbonate sediments

Laboratory measurements of electrical resistivity on two DSDP pelagic carbonate sequences permitted the study of the effect of diagenesis on the electrical and other physical properties such as velocity and porosity. Electrical resistivity and formation factor increase with sediment depth. Changes in porosity with progressive diagenesis (that is, ooze-chalk-limestone) are observed, and changes in pore geometry are inferred. These changes are interpreted in terms of systematic variations in electrical and physical properties. Influence of silica on carbonate diagenesis may result in significant change in pore geometry. This effect inhibits electrical conduction leading to complicated but generally high resistivity values for siliceous and cherty limestones. Compressional velocity correlates well with resistivity for both sequences.     

Experimental Investigation of the Response of Monopiles in Silty Seabed to Regular Wave Action

Excessive displacement responses of monopiles affect the serviceability of offshore structures. Related to complicated pile-seabed-wave interactions, the actual behavior of monopiles in silty seabed under periodic wave action remains unclear, and relevant studies in the literature are limited. A series of experiments were conducted in a wave flume containing single piles in silty seabed with relative density of 0.77 subjected to regular waves. Two stages of wave loading were applied successively...     

孟加拉湾季风对热带气旋生成和发展的调制机制研究

孟加拉湾与其他热带海盆不同,在季风影响下,该地区热带气旋具有双气旋季的独特结构(4—5月的春季转换期和10—11月的秋季转换期)。虽然孟加拉湾气旋频数在10—11月较多,但是4—5月超强气旋(Saffir-Simpson 4,5级)的生成率却远高于10—11月。1981—2016年,春季转换期内孟加拉湾超强气旋都与第一支北传季节内振荡(First Northward-propagating Intra-Seasonal Oscillation,FNISO)相应而生,然而并不是所有伴随FNISO发生的气旋都能发展成为超强气旋。因此本研究以气旋生成指数为基础,利用气旋最佳轨道数据以及NCEP的海气参量数据,诊断指出孟加拉湾夏季风形成的强垂直风速剪切配合低层大气旋度和气旋潜在强度抵消夏季风期间水汽对气旋生成的促进作用,造成双峰分布,而中层大气相对湿度差异双峰不对称的主因。FNISO强度的不同与深对流中心与气旋中心的相对位置的差异,使得部分气旋受季节内振荡影响更大,强深对流的超越作用导致更显著的高低层大气温差,促使气旋具有且达到更大的潜在强度。在年际尺度上大气高低层温差的不同也是引起气旋潜在强度不同的主要原因。当季节内尺度和年际尺度共同作用,使得部分气旋发展成为超强气旋。     

Short-term variability of the size spectra of suspended particles in a rapidly changing environment

Analysis of suspended matter collected in the lower St. Lawrence estuary indicated short-term variabilities in both the structure and dynamics of the particles. Variations with time and depth were ascribed to fluctuation of particle concentrations within the size ranges of the major peaks of concentration. A deterministic pattern was found for the temporal succession of the spectra when total particle concentrations were high. This was due to combinations of three factors that act in one of two ways, either (i) high current velocity—spring tide—stratified waters, or (ii) lower current velocity—neap tide—mixed waters. In the first case, the current effect prevailed, while the tide effect was dominant in the second one. A random pattern occurred in the succession of the spectra when lower particle concentrations and patches of smaller dimensions were present in well mixed water bodies. Successions of spectra were not always in phase at different depths within the water column.     

Non-uniqueness of the ocean thermohaline circulation,discontinuous auto-oscillations,and internal variability of the climatic system

Stable and unstable stationary thermohaline circulations provided by a box model comprising three ventilated masses—surface, intermediate, and deep—are discussed. The most likely states have been determined. It is shown that jump-like variations of the thermocline circulation are likely. An inference is made that long-term (10 000 years) climatic oscillations may be caused by the internal variability of the climatic system rather than by astronomical factors.     

How robust is the environmental impact assessment process in South Australia? Behind the scenes of the Adelaide seawater desalination project

This work tests the robustness of policies and procedures designed to protect South Australia's marine environment through a case study of the Adelaide Desalination Plant—the most expensive (∼A$1.8 billion) infrastructure project in South Australia's history. Although this project has been subject to an Environmental Impact Assessment (EIA)—the highest level of assessment in Australia—on inspection it appears that the current operating licence for the desalination brine discharge breaches Government approval conditions and ignores the collective expert scientific advice of the project's Environmental Impact Statement (EIS). Hence, the EIA process in South Australia for this project is flawed. Improvements could be made to the South Australian system by including the requirements for operating licences as an integral part of the EIA.     

Planning across boundaries for the conservation of the Sulu-Sulawesi Marine Ecoregion

The Sulu-Sulawesi Marine Ecoregion (SSME) is an outstanding ecoregion situated within the center of global marine biodiversity. Three countries—Indonesia, Malaysia and the Philippines—share, and directly benefit from, the rich resources of the SSME. The deterioration of environmental conditions in the ecoregion indicates that the resource extraction has exceeded the natural capacity of this marine ecosystem for recovery. Shared boundaries, ecosystem dynamics and resources, as well as transboundary environmental issues (including human migration) justify an ecoregion approach to conserve the SSME.In 1999, the World Wide Fund (WWF) for Nature and its partners launched the SSME Conservation Program. The Program adopts a two-pronged approach: planning for the conservation of the SSME and the implementation of immediate conservation actions on the ground. The ecoregion planning process involves the formulation of a Biodiversity Vision—a 50-year conservation goal—and the development of a stakeholders’ Ecoregion Conservation Plan (ECP) based on the ecoregion's Biodiversity Vision. Notable was a shift from a non-government organization-facilitated to a government-led planning process, and the establishment of interim governance mechanisms to ensure coordination in the development of the ECP. These interim mechanisms that operate within country and across countries during the planning phase of the SSME Program are perceived to evolve into formal institutional arrangements that are appropriate for the implementation of the ECP.     

Inconsistency in the conductivity of standard potassium chloride solutions made from different high-quality reagents

The salinity of seawater has been defined in terms of the ratio of its electrical conductivity to that of a standard potassium chloride solution. The potassium chloride solution is obtained by dissolution of high-purity potassium chloride in ultrapure water. However, even high-purity potassium chloride is not 100% pure, and suppliers do not certify it, as the standard for electrical conductivity. We prepared defined solutions using several kinds of high-purity potassium chloride and examined the difference between the measured electrical conductivity ratio and the value calculated from the experimental equation given in the UNESCO background papers. The differences between the electrical conductivity ratios of the solutions made from the various potassium chloride reagents were equivalent to about 0.0012 in salinity. The solution may not actually become a standard for salinity measurements even if it is prepared exactly according to the present definition. The lot dependency of the electrical conductivity ratio of the potassium chloride solutions may result in a systematic error in the measurement of salinity.     

The oxygen minimum zone of the eastern South Pacific

In spite of the fact that oxygen-deficient waters with ⩽20 μM of dissolved oxygen—known as oxygen minimum zones (OMZs)—occupy only ∼1% of the volume of the global ocean, they disproportionately affect global biogeochemical cycles, particularly the nitrogen cycle. The macrobiota diversity in OMZs is low, but the fauna that do inhabit these regions present special adaptations to the low-oxygen conditions. Conversely, microbial communities in the OMZ water column and sediments are abundant and phylogenetically and metabolically very diverse, and microbial processes occurring therein (e.g., denitrification, anammox, and organic matter degradation) are important for global marine biogeochemical cycles. In this introductory article, we present the collection of papers for the special volume on the OMZ of the eastern South Pacific, one of the three main open-ocean oxygen-deficient regions of the global ocean. These papers deal with aspects of regional oceanography, inorganic and organic geochemistry, ecology, and the biochemistry of micro and macro organisms—both in the plankton and in the sediments—and past changes in the fish scales preserved in the sediments bathed by OMZ waters.     

Deep structure and selected aspects of the oil and gas potential of the southern seas of Russia

Regional deep seismic sounding—refracted wave seismic profiles across the Sea of Azov, the Caspian, and the Black seas carried out by the Shirshov Institute of Oceanology, Russian Academy of Sciences, in 1957–2002 with the use ocean bottom seismographs—provided information on the deep structure of the regions studied. Multichannel seismic profiling helped to refine the structure of the sedimentary cover. A combined interpretation of the reflection and refraction data allowed us to construct structural-lithological models of the southern seas of Russia and to estimate their oil and gas potential.     

南黄海太阳沙西侧海域晚第四系地震层序和沉积环境演变

在南黄海太阳沙西侧潮流脊槽海域进行了密集网格的高分辨率浅地震勘探,测线间距主要为120 m和200 m。沉积物穿透厚度最大约80~90 m,划分为2个地震层序(SQ1和SQ2),细分为5个亚层(U1~U5)。位于下部的层序1(U1)为晚更新世陆相沉积,上部的层序2(U2~U5)以全新世海相沉积为主。根据地震相特征研究了各亚层的沉积环境,从晚更新世晚期以来,研究区经历了三角洲辫状河流—河流刻蚀—古河道充填—河口滨海—三角洲滨浅海—现代潮流脊槽的沉积环境演变过程。在早全新世中期,研究区发育了一条窄河口型潮流沙脊,并随海平面的快速上升而被掩埋。现代潮流沙脊形成于末次高海面后,与古潮流沙脊没有继承关系,与晚更新世古地形也没有关系,受控于潮流系统。     

Morphologic,acoustic, and sedimentologic characteristics of the Magdalena Fan

The Magdalena Fan can be divided into: upper fan—1:60–1:110 gradients, channels with well-developed levees, generally several subbottom reflectors on 3.5-kHz records, and fine-grained sediments; middle fan—1:110–1:200 gradients, channels with very subdued levees, several to few subbottom reflectors on 3.5-kHz records, and chaotic and discontinuous reflections on multichannel seismic (MCS) records; lower fan—<1:250 gradients, small channels and relatively smooth seafloor, generally coarsegrained sediments, few or no subbottom reflectors on 3.5-kHz records, and flat continuous reflections on MCS records. In addition to the turbidity currents, slumping along the continental slope and elsewhere also influenced sedimentation in the fan.     

Harpacticoida taxocen diversity in the silty-sandy littoral zone of Kandalaksha Bay of the White Sea

The fauna composition, ecological groups, and life forms of Harpacticoids of soft littoral grounds from 15 sites off the Karelian coast in Kandalaksha Bay of the White Sea were studied. Six types of harpacticoid taxocens with different sets of dominating species are described. On silty sands with clear signs of desalination, the Stenchelia palustris taxocen is common; medium-grained sands are characterized by the Heterolaophonte minuta, Paraleptastacus kliei — Huntemannia jadensis, and Amphiascoides nanus — Scottopsyllus minor taxocens; while on coarse sands, the Ameira parvula and Ameira scotti — Mesochra lilljeborgi taxocens have developed. The diversity of the taxocens is partly explained by the differences in the grain-size composition and salinity at different sites. In addition, groups of various taxocens dwelling on the same type of the sediments were found in different minor bights of the coastline.     

Electromagnetic fields of waves in the sea stratified over density and electrical conductivity

The paper addresses the theoretical problem of electromagnetic fields induced by surface and internal waves in a fluid with continuously stratified electrical conductivity and density. Calculations of the electromagnetic fields induced by the wave motion in the tropical Atlantic have been performed considering the exponentially changing electrical conductivity in the vertical. The consideration of the electrical conductivity stratification is shown to be capable of modifying electromagnetic fields in the individual fluid layers by about 50%, and the role of this stratification is shown to increase with the growth of the wave period. Translated by Vladimir A. Puchkin.     

Resonant interaction of waves of continuous and discrete spectra in the simplest model of a stratified shear flow

The equations of dynamics of eddy—wave disturbances of two-dimensional stratified flows in an ideal incompressible fluid that are written in a Hamiltonian form are used to study the resonant interaction of waves of discrete and continuous spectra. A gravity—shear wave generated at a jump of the density and vorticity of the undisturbed flow and a wave generated at a weak vorticity jump, which is similar to a wave of a continuous spectrum, participate in the interaction. The equations are written in terms of normal variables to obtain the system of evolution equations for the amplitudes of the interacting waves. The stability condition for eddy—wave disturbances is derived within the framework of the linear theory. It is shown that a cubic nonlinearity may lead to the stabilization of unstable disturbances if the coefficient of the nonlinear term is positive.