Environmental changes in the Amur Bay (Japan/East Sea) during the last 150 years revealed by examination of diatoms and silicoflagellates     

Tsoy  Ira  Prushkovskaya  Irina  Aksentov  Kirill  Astakhov  Anatoly 《Ocean Science Journal》2015,50(2):433-444

Siliceous unicellular microalgae — diatoms and silicoflagellates from sediments in Amur Bay were analyzed with high temporal resolution to examine changes over the last 150 years. The age of sediments was estimated from unsupported ²¹⁰Pb controlled by ¹³⁷Cs. Siliceous microalgae examined in each cm of two sediment cores demonstrated significant changes in the ecological structure of the assemblages that reflected changes in sedimentation conditions. During the years 1860–1910 the sediments accumulated under the great influence of river runoff. For about the next 50 years the number of freshwater species and marine benthic diatoms in sediments sharply declined, which is probably connected with the weakening of the effects of river runoff due to deforestation. Since the early 1960s the sedimentation conditions in the Amur Bay changed significantly. Marine planktonic diatoms and silicoflagellates began to prevail in sediments and this reflects increasing microphytoplankton productivity. One consequence of this was the formation of seasonal bottom hypoxia in Amur Bay. The ecological structure of diatom and silicoflagellate assemblages indicates that the sea level began to rise since the early 1960s and this corresponds to the water and air temperature increase in the area for that period. The obtained data suggest that the environmental changes over the last 150 years in Armur Bay are associated with the weakening of river runoff due to deforestation, sea level rise caused by global warming, and the increase of siliceous microplankton productivity that resulted in the formation of seasonal bottom hypoxia.

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Dynamics of accumulation of heavy metals by subcolloidal fraction of bottom sediments is a result of biochemical processes in the marginal filter of the Razdol’naya River (the Amur Bay, the Sea of Japan)     

D. M. Polyakov  K. I. Aksentov 《Russian Meteorology and Hydrology》2013,38(11):776-781

Determined is the content of Fe, Mn, V, Cr, Cu, Zn, Pb, As, and Sc in the subcolloidal fraction of sediments of the Razdol’naya River marginal filter using the method of atomic emission spectroscopy. Proposed is one of the variants of separating biochemical zones with the increased content of Fe and Mn and other metals in the bottom sediments of the marginal filter: the river zone, the zone of flocculation and formation of Fe and Mn hydroxides, and the zone of biochemical metal accumulation (marine). In the sediments of the river zone and the zone of flocculation and formation of Fe and Mn hydroxides, two bottom areas are identified with the high content of the elements under study that is associated with long-term and seasonal variations of the river runoff.  相似文献   

Petrogeochemistry and Ore Mineralization of Sericite–Quartz Schists of the Southern Slope of the Kashevarov Bank (Sea of Okhotsk)     

Astakhova  N. V.  Ivanov  V. V.  Aksentov  K. I. 《Oceanology》2021,61(5):701-713

Oceanology - Data on the structure and chemical and mineral composition of sericite–quartz schists of the southern slope of the Kashevarov Bank of the Sea of Okhotsk are presented. The...  相似文献   

Rare Earth Elements in the Bottom Sediments of the East Arctic Seas of Russia as Indicators of Terrigenous Input   总被引：1，自引：0，他引：1  

A. S. Astakhov  I. P. Semiletov  V. V. Sattarova  Xuefa Shi  Limin Hu  K. I. Aksentov  Yu. P. Vasilenko  M. V. Ivanov 《Doklady Earth Sciences》2018,482(2):1324-1327

The REE distribution was studied in the bottom sediments of the East Arctic shelf of Russia. It is established that sediments of the Laptev and western East Siberian seas are significantly enriched in REEs, the contents of which are much higher than those of other near-continental basins. The main REE sources are runoff of the Lena River, the basin of which comprises ancient crystalline shields and magmatic rocks enriched in LREEs with significant contribution from the coastal erosion of the ice complex from the Laptev Sea and western East Siberian Sea. The terrigenous flux with a specific REE composition is supplied to the Chukchi Sea through the Bering Strait.  相似文献   

The first discovery of cryptotephra of the catastrophic eruptions of the Baitoushan volcano in the tenth century A.D. in the shelf deposits of the Sea of Japan     

V. A. Akulichev  A. S. Astakhov  M. I. Malakhov  K. I. Aksentov  A. A. Karabtsov  A. A. Mar’yash  A. V. Alatortsev 《Doklady Earth Sciences》2016,469(2):887-891

The interlayers of the cryptotephra of different episodes of the catastrophic eruption of the Baitoushan volcano (Paektu-san, Changbaishan-Tianchi) in the 10th century were discovered in the sedimentary cover of Amur Bay in the Sea of Japan by the geochemical and paleomagnetic characteristics. The petrochemistry of the volcanic glass indicates the possible occurrence of pyroclastic material in the B–Tm layer and more recent episodes that have not been identified before in the sediments of the Sea of Japan. The impact of the eruption on the bay environment is noted. It is shown that the medieval state of Balhae occupying vast areas and adjacent to the volcano no longer existed after the more earlier episodes of eruption.  相似文献   

Mercury inflow to the Amur Bay (the sea of Japan) after the passage of typhoons in 2015     

K. I. Aksentov 《Russian Meteorology and Hydrology》2017,42(11):723-727

Mercury levels in the abiotic components of the Razdol’naya River-Amur Bay geosystem are determined. The obtained mercury concentrations correspond to modern global values. Mercury accumulated in the deposit environments is transported to the bay during floods and creates a local geochemical background. The migration of mercury is carried out in the form of suspended matter and single fragments of soil cover which can be deposited in the open parts of the Peter the Great Gulf shelf according to the existing circulation of surface waters.  相似文献   

Atomic mercury distribution features in the surface air layer in the Sea of Japan in the fall of 2010     

K. I. Aksentov  V. V. Kalinchuk 《Russian Meteorology and Hydrology》2012,37(10):674-680

Presented are the results of mercury content measurements in the surface air layer in the Sea of Japan in the period from October 27 to November 11, 2010. It is revealed that the mercury content varied from 0.6 to 3.8 ng/m³. It is demonstrated that the mercury concentration distribution has geographical zoning and depends on the movement of air masses and on the closeness of anthropogenic sources. The maximum mercury concentration is detected in the central part of the sea at the southwestern and southern directions of the wind, that is associated with the industrial emissions of East Asia countries. The minimum mercury concentration corresponding to the concentration in the surface air layer of the Arctic, Atlantic Ocean (Northern Hemisphere), and the Sea of Okhotsk and Bering Sea was observed along the coast of Primorye at the northwestern wind direction.  相似文献   

Ore Mineralization in Pleistocene Sediments of Long Strait (East Siberian Sea)     

Goryachev  N. A.  Sotskaya  O. T.  Astakhov  A. S.  Xuefa  Shi  Mikhalitsyna  T. I.  Aksentov  K. I.  Berdnikov  N. V. 《Doklady Earth Sciences》2020,491(2):220-223

Doklady Earth Sciences - A mineralogical–geochemical study of Late Pleistocene bottom sediments of the LV 77-10 core collected in the central part of Long Strait was carried out. Two horizons...  相似文献   

Mercury in the bottom sediments of the marginal filter of the Razdol’naya River,Amur Bay     

D. M. Polyakov  K. I. Aksentov  M. V. Ivanov 《Geochemistry International》2008,46(6):614-621

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

Valitov  M. G.  Shakirov  R. B.  Yatsuk  A. V.  Aksentov  K. I.  Proshkina  Z. N.  Belous  O. V.  Mishukova  G. I. 《Oceanology》2019,59(2):283-286

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