Pacific Oceanological Institute Research Articles

Isotopic composition of natural waters of Kuzbass in coalbed methane production areas

Relevance. In Kuzbass, a coalbed methane production project is being implemented for the first time in Russia. Formation water extracted together with coalbed methane plays an important role, since it has been in contact with the coal-bearing rocks for a long time, therefore it contains rich geochemical information. Over the period 2002–2022, new isotopic data were accumulated both on the waters of the region coal deposits and on overlying waters, including surface waters. Aim. Based on the material accumulated on the isotopic composition (δD, δ18O, δ13C, 34S, 3H, 14C) of natural waters in coal-bearing areas, create an evolutionary scheme for the formation of waters within the framework of the developed hypothesis on the interaction of water-rock-coal-methane. Objects. River, underground waters of the zone of active water exchange, upper and lower parts of the zone of slow water exchange (extracted together with coalbed methane). Methods. Studies of the isotopic composition of waters were carried out in several laboratories: in the Multielement and Isotope Research Center of the SB RAS, the Technical Branch of the Federal State Unitary Enterprise “SNIIGGIMS”, in the radiocarbon AMS laboratory based on the Center for Collective Use “Cenozoic Geochronology” and in the Pacific Oceanological Institute Far Eastern Branch Russian Academy of Sciences (POI) FEB RAS. Results and conclusions. The paper introduces the data on δD, δ18О, δ13С и δ34S for surface and groundwater in Kuzbass in coalbed methane production areas. It is shown that all the waters under consideration are infiltration based on their isotopic composition (δD and δ18О). The waters of the lower part of the slow water exchange, produced together with coalbed methane, are characterized by a positive oxygen shift and very light hydrogen. A diagram of the evolution of the isotopic composition of water-dissolved carbon in the region has been compiled according to the data obtained. It is noted that the atmospheric source of CO2 is characteristic only of river waters, and only biogenic carbon dioxide is present in groundwater. The wide range of δ13СDIC values of the latter is explained by the varying degrees of participation of light soil carbon dioxide and heavy biochemical carbon dioxide formed during methane formation in the coal seam. The heaviest values are typical for waters produced together with coalbed methane, which is associated with long-term interaction with coal and methane. The time of such interaction was determined using the radiocarbon method: 17–30 thousand years. In areas where coalbed methane is produced, an increase in δ13СDIC values for all natural waters is observed, which requires further study.

Комплексные геолого-геофизические исследования по обоснованию внешней границы континентального шельфа России в Охотском и Восточно-Сибирском морях (2006–2009 гг.): обзор

The paper discusses the results of complex geological and geophysical studies of the deep structure of the seabed along the profiles “Magadan – Southern Kurils” (2-DV-M), “Shantar Islands – Northern Kurils” (1-OM) and “Cape Billings – Outer Continental Shelf Limits” (5-AR), carried out in 2006–2009 within the framework of the State program of expeditionary works on substantiation of national sovereignty over the continental shelf in the Sea of Okhotsk and East Siberian Sea. The main executors were the staff of the V.I. Il’ichev Pacific Oceanological Institute of FEB RAS and Federal State Unitary Scientific and Production Company (FSUSPC) Sevmorgeo. A special role was assigned to gas-geochemical studies with the purpose to establish regional background and anomalous gas fields to assess prospects for oil, gas and gas hydrates. As a result of complex geological and geophysical expeditions led by A.A. Merezhko (Sevmorgeo) in the Sea of Okhotsk, it was established that the enclave outside the 200-mile zone in the central part of the water area does not differ in geological structure from the adjacent parts and is a natural continuation of the framing geological structures of the basement. The evidence obtained was sufficient to successfully justify the application to the UN. On March 11, 2014, after careful consideration of the application and draft recommendations, the enclave of international waters in the Sea of Okhotsk was legally assigned to the Russian Federation. Studies in the East Siberian Sea have provided a huge amount of data on lithology, geochemistry and gas potential of bottom sediments in this area.

Научное сотрудничество Вьетнамской академии наук и технологий (ВАНТ) и ТОИ ДВО РАН

The paper presents information about the cooperation of the Vietnam Academy of Sciences and Technologies (VAST) and the V.I. Il'ichev Pacific Oceanological Institute FEB RAS (РOI FEB RAS) in the field of marine research and study of the South China Sea. Long-term joint research includes a large complex of hydrological, hydrophysical, hydrochemical, geological, geophysical, gas geochemical work, covering not only the waters of Vietnam, but also islands in the Gulf of Tonkin, and areas of thermal springs along the Red River rift valley in the territory of Vietnam. To develop Russian-Vietnamese research, a joint Russian-Vietnamese laboratory for marine sciences and technologies was created in 2010.

Methane Fluxes at the Water–Atmosphere Interface and Gas-Geochemical Anomalies in the Bottom Sediments in the Northwestern Part of the Sea of Japan

Abstract —We present results of an integrated research into the spatial distribution of methane in the area of the northern closure of the Central Basin of the Sea of Japan and in the southern part of the Tatar Trough. Methane emissions have been revealed in the study area. The methane fluxes are distributed unevenly within the area (1 to 23 mol/(km2·day)). The discrete high-frequency measurements and calculation of methane fluxes at the water–atmosphere interface, combined with the study of the content of natural gases and microbiologic parameters in sediment cores, allow us to explain the formation of local methane emission zones in the water area. Despite the great sea depths, there are sources and fluid-conducting zones that determine methane concentrations (exceeding the equilibrium ones) and high methane emissions from the water area. The data obtained provide new information and suggest the presence of deep gas sources, which determine gas dispersion in the bottom sediments, the methane content in the surface water layer, and the distribution of methane fluxes at the water–atmosphere interface in the study area. This study is part of the integrated program of geological and geophysical expeditionary research performed by V.I. Il’ichev Pacific Oceanological Institute (Vladivostok) in the northern part of the Sea of Japan.

Hydrothermal Ore Genesis in the Sea of Japan

Abstract —The Sea of Japan is a tectonically active region with rift-related destruction of the Earth’s crust and numerous volcanic edifices on the seafloor. Since the 1970s, numerous zones with ferromanganese crusts (FMCs) and phosphorite and barite ore occurrences have been discovered during the repeated expeditions of the Pacific Oceanological Institute, Vladivostok. Analysis of the distribution of these ore occurrences showed that all of them are confined to tectonically active zones of the seafloor: submarine volcanoes, tectonic scarps, or fault zones. In some zones, phosphorites occur together with FMCs, and in one zone, together with FMCs and barites. Ferromanganese hydroxides, phosphorites, or barites are found in the pores of basalts composing submarine volcanic edifices in the Sea of Japan. These data indicate that the ore matter in all zones is supplied with postvolcanic gas-hydrothermal fluids or hydrothermal solutions circulating along deep faults during the destruction of the continental crust in the southern and eastern parts of the sea. Thus, ferromanganese, phosphate, and barite ore occurrences in the Sea of Japan are related to low-temperature hydrothermal-sedimentary processes.

Geological features for the formation of gas-geochemical fields, including helium and hydrogen, in the water and sediments at the Vietnamese part of the South-China Sea

The paper presents the results of a complex joint Russian-Vietnamese geological, geophysical and oceanographic expedition in the South-China Sea (R/V “Akademik M.A. Lavrentyev”, cruise 88, 2019), as well as related joint Russian-Vietnamese marine and land researches in the area of north and south Vietnam under a series of local FEB RAS – VAST grants. The organizers of the marine expedition are the V. I. Ilyichev Pacific Oceanological Institute of the Far Eastern Branch of the Russian Academy of Sciences (POI FEB RAS) and the Institute of Marine Geology and Geophysics of the Vietnam Academy of Science and Technology (IMGG VAST). In comparison with the Sea of Japan and the Sea of Okhotsk, it can be noted that the active bottom degassing on the on the Vietnamese shelf and slope have is a local, although the intensity of gas-geochemical anomalies is comparable to similar zones in the Far Eastern Seas. For the first time, anomalous methane fields (up to 5000 nl/l) were found in the water column of the South-China Sea, which are comparable to anomalies on the oil and gas shelf and the gas-hydrate-bearing slope of Sakhalin Island. Metamorphosed sedimentary and volcanic rocks were discovered for the first time in the southern part of Catba Island (Gulf of Tonkin), which indicates the introduction of an endogenous body into the sedimentary strata and its further transformation. In connection with the discovery in 2020 of the large Ken Bau gas field at the southern end of the sedimentary basin of the Red River, the forecast of POI scientists about the presence of significant hydrocarbon reserves in this area was confirmed. The work was carried out within the framework of the joint Vietnam-Russia Laboratory for Marine Sciences and Technology (V. I. Ilyichev Pacific Oceanological Institute of the Far Eastern Branch of the Russian Academy of Sciences and the Institute of Marine Geology and Geophysics Vietnam Academy of Science and Technology). The expedition of the R/V “Akademik M.A. Lavrentyev” (cruise 88) is part of a series of expeditions in accordance with the UN Decade dedicated to the Ocean Science for Sustainable Development.

Formation of anomalous gas fields of helium and hydrogen in the Cat Ba, Co To and Bach Long Vi islands, northern Vietnam

Data of methane, helium and hydrogen concentrations in the mineral waters, as well as in the subsurface atmosphere, of the Cat Ba, Co To and Bach Long Vi islands, shows that the regions belong to degassing zones of hydrogen and helium, and points at gas condensate potential of the Bac Bo sedimentary basin. A joint transit of these gases via the fault structures was established. Distribution patterns of hydrogen and helium concentrations from these islands (Tonkin Gulf) were obtained from the gas and water sample data. Thermogenic and metamorphogenic gases detected in hydrogeological wells on Cat Ba island and gas anomalies in subsurface gas indicate natural gas emission through permeability zones.
 The work was carried out within the framework of the joint Russian-Vietnamese Laboratory on Marine Geosciences (V.I.Il`ichev Pacific Oceanological Institute FEB RAS and Institute of Marine Geology and Geophysics, VAST). The research involves the staff and scientific equipment of the new innovative Laboratory for Integrated Research of the Environment and Mineral Resources (LIREMR) of the POI FEB RAS, created within the framework of the SCIENCE national project.

Integrated Expeditionary Research in the Sea of Japan and the Sea of Okhotsk on Cruise No. 55 of the R/V Akademik Oparin

According to the Plan of Complex Scientific Research of the World Ocean for 2017–2022, the V.I. Il’ichev Pacific Oceanological Institute, Far Eastern Branch, Russian Academy of Sciences, continues to study the northern part of the Sea of Japan and the Tatar Strait, carrying out a three-year plan of expeditionary research of this region. The expedition aboard the R/V Akademik Oparin (cruise no. 55) spanned from October 2 to 19, 2018. Geophysical and gas-geological study of the water area in the central and southern parts of the Tatar Strait was continued. On the rookery of Tyuleny Island, in the Sea of Okhotsk, information on sea lions and larghas were recorded, three individuals of northern fur seal were tagged with satellite trackers to study their migration routes. CTD observations of the upper layer (down to 600 m) were made on transects across mesoscale eddies in the northern part of the Sea of Japan. Expeditionary research was supported by the Council of the Earth’s Hydorsphere of the Ministry of Science and Higher Education of the Russian Federation.

The integrated geological and geophysical expedition aboard the R/V Akademik Oparin to the Tatar Strait, Sea of Japan (cruise No. 54, 2017)

According to the Plan of Integrated Scientific Research of the World Ocean for 2017–2022, the Il’ichev Pacific Oceanological Institute, Far Eastern Branch of the Russian Academy of Sciences (POI FEB RAS) began a comprehensive study of the northern part of the Sea of Japan and the Tatar Strait, having developed a three-year plan for expeditionary research in the area. The first expedition from the three-year expeditionary research cycle was carried out from September 21 to October 31, 2017 on the R/V “Akademik Oparin” (cruise № 54). The main goal of the expedition was to study the geological structure, conditions and mechanisms for the formation of the Tatar Strait, to study the correlation of the distribution of gas-fluid flows with a network of tectonic disturbances of different ranks in one of the seismic areas of Sakhalin Island, as well as the reaction of the Sea of Japan to climate change and increasing anthropogenic impacts.

The international conference “Vortices and coherent structures: from ocean to microfluids”, Vladivostok, Russia, 28–31 August 2017

The international conference “Vortices and coherent structures: from ocean to microfluids” was held at the Pacific Oceanological Institute of the Russian Academy of Sciences in Vladivostok (Russia) from August 28 to August 31, 2017. The event gathered experimentalists and theoreticians, oceanographers and physicists, with a common interest in observing and modelling fluid flows in different media, from the ocean to laboratory flows. It was a fruitful idea to bring together researchers from a variety of backgrounds to benefit from a vigorous discussion of concepts across different disciplines in oceanography and hydrodynamics.

Integrated Geological and Geophysical Expedition aboard the R/V Akademik Oparin to the Tatar Strait, Sea of Japan (Cruise 54, 2017)

According to the Plan of Integrated Scientific Research of the World Ocean for 2017–2022, the Il’ichev Pacific Oceanological Institute, Far Eastern Branch of the Russian Academy of Sciences (POI FEB RAS) began a comprehensive study of the northern part of the Sea of Japan and the Tatar Strait, having developed a three-year plan for expeditionary research in the area. The first expedition from the three-year expeditionary research cycle was carried out from September 21 to October 31, 2017 on the R/V “Akademik Oparin” (cruise № 54). The main goal of the expedition was to study the geological structure, conditions and mechanisms for the formation of the Tatar Strait, to study the correlation of the distribution of gas-fluid flows with a network of tectonic disturbances of different ranks in one of the seismic areas of Sakhalin Island, as well as the reaction of the Sea of Japan to climate change and increasing anthropogenic impacts.

Tephra layers of large explosive eruptions of Baitoushan/Changbaishan Volcano in the Japan Sea sediments

This paper is based on the results of a comprehensive investigations of sediments from seven cores sampled during the International Russian-Chinese Cruise 53 of the R/V “Akademik Lavrentyev” (2010) in the frames of the Russian-Chinese collaboration between the Pacific Oceanological Institute of the Far-Eastern Branch of the Russian Academy of Sciences (POI FEB RAS, Vladivostok, Russia), and the First Institute of Oceanography (FIO, Qingdao, China). Baitoushan (Chanbaishan) Volcano had several powerful explosive eruptions during the Middle Pleistocene-Holocene, which produced widespread tephra layers. The paper reports chemical composition of volcanic glasses and minerals from six tephra layers labeled as B-Og, B-Sado, B-J, B-Un1, B-V, and B-Tm, which belong to Baitoushan Volcano and were identified in sediments of the northwestern part of the Sea of Japan. The tephras were dated using geochronological data for the host sediments. The estimated ages for the Middle Pleistocene tephra is 488 ka; the Late Pleistocene tephras are 71.1–71.9 cal. kа (B-Sado), 50.8 cal. ka (B-J), 38.3 cal. ka (B-Un1), and 29.0–29.4 cal. ka (B-V). The ash layers consist of alkali-rich glass of trachydacitic to alkaline rhyolitic composition and specific assemblage of minerals including Fe-rich augite-hedenbergite, aegirine-augite, aegirine, arfvedsonite, and fayalite. The mineral assemblage is typical for alkalic volcanic rocks from continental rift setting. Aenigmatite, a rare mineral from the group of inosilicates, was firstly identified in distal tephra of Baitoushan Volcano, supplied into marine sediments. The composition of glasses and minerals from all layers are similar. It testifies about steady-state conditions of the magma accumulation under Baitoushan Volcano and about the bimodal character of magmatic chambers during the Late Pleistocene and Holocene (since 100 ka).

Features of the Distribution of Abnormal Gasgeochemical Fields in the Red River Rift (Gulf of Tonkin, South China Sea)

This paper reports the results of the third Russian–Vietnamese expedition (V.I. Il'ichev Pacific Oceanological Institute, Far East Branch, Russian Academy of Sciences and the Institute of Marine Geology and Geophysics, Vietnam Academy of Science and Technology) in the Gulf of Tonkin, South China Sea (April 2016). The studies revealed new specific features of the distribution and origin of gasgeochemical fields in sediments within the rift zone of the Red River along a 150-km profile. Four zones with high-amplitude anomalies of hydrocarbon gases, helium, hydrogen, carbon dioxide, and carbon monoxide were revealed. The distribution of the anomalies reflects the tectonic structure of the area and points to the presence of several lithospheric sources of gases including gases of deep origin. The studies were carried out within the scope of the Joint Vietnamese–Russian Laboratory for Marine Geoscience (V.I. Il'ichev Pacific Oceanological Institute, Far East Branch, Russian Academy of Sciences and the Institute of Marine Geology and Geophysics, Vietnam Academy of Science and Technology).

ИТОГИ XVI ШКОЛЫ-СЕМИНАРА ИМЕНИ АКАДЕМИКА Л.М. БРЕХОВСКИХ «АКУСТИКА ОКЕАНА»

This short communication presents the report on the XVI School-seminar named after academician L.M. Brekhovskikh. The conference combined with the XXXI session of the Russian Acoustic Society was held at Shirshov Institute of Oceanology, RAS in May 29 - June 1, 2018. The objectives of the conference were as follows: overview the ongoing research by Russian scientists in the field of ocean acoustics, present new results and exchange of opinions among members of the ocean acoustics community, discuss new priorities and future projects. The conference was attended by more than 150 participants from Shirshov Institute of Oceanology (Moscow), Ilyichev Pacific Oceanological Institute (Vladivostok), Prokhorov Institute of General Physics (Moscow), Institute of Applied Physics (Nizhniy Novgorod) and Andreev Acoustics Institute (Moscow), as well as from Sevastopol State University and Lomonosov Moscow State University. 87 reports were published in the volume Ocean Acoustics, Proceedings of the XVI L.M. Brekhovskikh Conference, Edited by V.V. Goncharov, T.I. Tsyplakova. Moscow: GEOS, 2018, 436 p. ISBN 978 5-89118-768-9.

Technical Tools for Underwater Monitoring of Seismic Survey Operations on the Shelf

Abstract—The article presents a new modification to a measuring–recording apparatus developed at the Il’ichev Pacific Oceanological Institute, Far Eastern Branch, Russian Academy of Sciences, to monitor anthropogenic noise levels on the northeastern shelf of Sakhalin Island. The functional possibilities of the original devices, modules, and software are described. The main device of the apparatus is the Shelf-2014 underwater bottom station, which records acoustic pressure variations in the 2–15 000 Hz frequency range. For operation in real time, the station is supplemented with a telemetry buoy. The Iridium satellite network serves as the buoy’s data transmission channel. Software at a shore post makes it possible to view the acoustic conditions in real time. The coordinates and technical status of bottom stations and buoys are controlled automatically. An operator receives on-screen notification when the parameters go beyond the permissible limits. The modified apparatus was tested on the shelf of the Sea of Japan.

Assessing the effect of environmental factors on the spawning activity of the sea urchin Strongylocentrotus intermedius through video recording observations

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 588:101-119 (2018) - DOI: https://doi.org/10.3354/meps12436 Assessing the effect of environmental factors on the spawning activity of the sea urchin Strongylocentrotus intermedius through video recording observations Peter M. Zhadan1,*, Marina A. Vaschenko2, Sergey D. Ryazanov1 1V. I. Il’ichev Pacific Oceanological Institute, Far Eastern Branch, Russian Academy of Sciences, 43 Baltiyskaya Street, 690041 Vladivostok, Russia 2National Scientific Center of Marine Biology, A. V. Zhirmunsky Institute of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, 17 Palchevsky Street, 690041 Vladivostok, Russia *Corresponding author: pzhadan@poi.dvo.ru ABSTRACT: We used video recordings of spawning behaviour of the sea urchin Strongylocentrotus intermedius conducted in parallel with an analysis of gonadal state and measurement of environmental variables (tidal level, phytoplankton, temperature, salinity and oxygen concentration) in situ to study the role of environmental factors in triggering sea urchin spawning. The observations were performed during 3 reproductive seasons, each of 2 mo duration, in 2 bays with different levels of phytoplankton (measured as chlorophyll a [chl a]). The only significant positive correlation found was between sea urchin spawning frequency and chl a concentration. Despite a high level of gonad maturity, sea urchin spawning was rarely recorded in the bay with low levels of chl a whereas mass spawning occurred in the bay with higher chl a concentration, with the peak of spawning activity centred around the full moon. Spawning was predominantly nocturnal. Immediately before and during spawning, males actively moved. Females began to spawn only when there were several spawning males nearby. In both sexes, each spawning event included several episodes of gamete release of different duration and with different intervals between them. The same male likely can participate in several spawning events. The following hierarchy of drivers of S. intermedius spawning activity was revealed: (1) increasing the phytoplankton concentration induced active motion and spawning in males, (2) both an elevated phytoplankton level and the presence of sperm stimulated spawning in females and (3) the night time and the new and full lunar phases increased the probability of spawning. KEY WORDS: Broadcast spawning · Echinoderms · Reproductive synchrony · Phytoplankton · Temperature · Circadian rhythm · Lunar cycle Full text in pdf format Supplementary material PreviousNextCite this article as: Zhadan PM, Vaschenko MA, Ryazanov SD (2018) Assessing the effect of environmental factors on the spawning activity of the sea urchin Strongylocentrotus intermedius through video recording observations. Mar Ecol Prog Ser 588:101-119. https://doi.org/10.3354/meps12436 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 588. Online publication date: February 08, 2018 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2018 Inter-Research.

Fine-scale temporal study of the influence of hydrobiological conditions on the spawning of the sea urchin Strongylocentrotus intermedius

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 550:147-161 (2016) - DOI: https://doi.org/10.3354/meps11678 Fine-scale temporal study of the influence of hydrobiological conditions on the spawning of the sea urchin Strongylocentrotus intermedius Peter M. Zhadan1,*, Marina A. Vaschenko2, Vyacheslav B. Lobanov1, Aleksandr F. Sergeev1, Svetlana A. Kotova3 1V. I. Il’ichev Pacific Oceanological Institute, Far Eastern Branch, Russian Academy of Sciences, 43 Baltiyskaya Street, 690041 Vladivostok, Russia 2A. V. Zhirmunsky Institute of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, 17 Palchevsky Street, 690041 Vladivostok, Russia 3Far Eastern Federal University, 8 Sukhanova Street, 690091 Vladivostok, Russia *Corresponding author: pzhadan@poi.dvo.ru ABSTRACT: The role of environmental variables in the triggering and synchronization of spawning in natural populations of broadcast invertebrates is not fully understood. Here, we report the results obtained from a fine-scale temporal study of the timing of spawning of the sea urchin Strongylocentrotus intermedius and the associated environmental conditions in the northwestern Sea of Japan. Sea urchins were sampled in August-September of 2011 (3 sites) and 2012 (4 sites) at intervals of 3-12 d (4.2 d on average). Sixteen spawning events were revealed by a significant increase in the number of spawned females and a decrease in the gonad index and/or in the portion of individuals ready for spawning, determined as the percentage of sea urchins releasing gametes after dissection from the gonopores. Depth, temperature, salinity, dissolved oxygen and chl a concentrations were measured by sounding of the water column at the sampling sites daily and at 26 other sites in the bay every 5 d in 2011 and every 3 d in 2012. At one of the sampling sites, environmental parameters were recorded every 15 min by a data logger. No apparent relationships were found between temperature, salinity, dissolved oxygen or tidal activity and the timing of spawning, but there was a significant positive relationship between chl a concentration and the spawning events. Our results strongly suggest that phytoplankton concentration is the main factor for initiation of S. intermedius spawning and that the lunar cycle may serve as an additional factor which is able to affect this process. KEY WORDS: Broadcast spawning · Echinoderms · Reproductive success · Phytoplankton bloom · Temperature · Upwelling · Downwelling · Moon cycle Full text in pdf format Supplementary material PreviousNextCite this article as: Zhadan PM, Vaschenko MA, Lobanov VB, Sergeev AF, Kotova SA (2016) Fine-scale temporal study of the influence of hydrobiological conditions on the spawning of the sea urchin Strongylocentrotus intermedius. Mar Ecol Prog Ser 550:147-161. https://doi.org/10.3354/meps11678 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 550. Online publication date: May 25, 2016 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2016 Inter-Research.

Absolute gravity measurements at shults cape

This work presents the results of the measurements of absolute gravity value g obtained over four field seasons in 2010–2013 at marine expeditionary station of Pacific Oceanological Institute at Shults Cape of Gamov peninsular (42.58° N, 131.15° E, Russia). The measurements revealed that during the first year the absolute g at the measurement point increased by 5.1 μGal, and during the second year, by 3.2 μGal. The auxiliary point No. 2 located 46 m below the main point No. 1 was founded in 2012 to create a gravimetric test site for calibration of the tidal gravimeter g-Phone.

A radiohydroacoustic station for monitoring the parameters of anthropogenic impulse and noise signals on the shelf

The paper presents a description and the technical characteristics of an autonomous hydroacoustic station developed at the Pacific Oceanological Institute, Far Eastern Branch, Russian Academy of Sciences (TOI DVO RAN) for stationary measurements of variations in acoustic pressure in the frequency range of 2–15 000 Hz on the shelf at the bottom. To organize real-time monitoring of the parameters of seismic survey impulse signals and industrial acoustic noise, the station is additionally equipped with a digital UHF–FM radio telemetry channel. Acoustic data measured in the frequency band of 2–2000 Hz is transmitted through the channel to a shore post, as well as via an Iridium satellite radio telemetry channel. It controls the operation of the UHF–FM radio transmitter and transmits the results of special analysis of acoustic data obtained in subsequent 1 min time intervals.

Salinity minimum in the subsurface layers of the Japan Sea

Seasonal variability of vertical salinity distribution in the Japan Sea is considered. On the base of high accuracy data from the databases WODC-2013 (USA), JODC (Japan), and the databases of Far-Eastern State Hydrometeorological Institute and Pacific Oceanological Institute (Russia), several cases of salinity minimums are analyzed and interpreted taking into account seasonal variability of salinity profiles. High vertical homogeneity by salinity is noted for the Japan Sea waters, and the subsurface salinity minimum can be considered as a result of continuous changes of freshwater balance. It could be formed in the layers from the sea surface to 150-250 m as a temporary local extreme caused by prevalence of evaporation over precipitation on the sea surface in some seasons - that’s why it is observed seasonally. There is concluded that such conservative patterns as water masses are absent in the sea, at least in its active upper layers, but vertical salinity profiles are changing permanently under influence of changing freshwater fluxes, and their extremes appear or disappear in compliance with the dialectic laws.