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911.
912.
V. I. Kaevitser N. A. Rimskii-Korsakov I. V. Smolyaninov V. M. Razmanov A. P. Krivtsov 《Oceanology》2016,56(5):714-720
This paper presents the results of three-dimensional acoustic seabed mapping in the region of the Taman Peninsula in the Black Sea using an interferometric side-scan sonar and an acoustic profiler. Mapping has revealed underwater objects identified as manifestations of underwater mud volcanism. Detailed analysis of sonar images of the relief and seabed profiles in the region of the objects has confirmed the original hypothesis. 相似文献
913.
The threat status of 74 freshwater and estuarine fish present in New Zealand was determined. Fifty-one native taxa were ranked of which 67% were considered Threatened or At Risk. A single species was classified as Extinct, the New Zealand grayling, which has not been observed since the 1920s. Four taxa were classified in the highest threat category, Nationally Critical, and a further 10 taxa as Threatened (Nationally Endangered or Nationally Vulnerable). Twenty taxa were ranked in the At Risk group with the majority ranked as Declining. Endemic galaxiids (Galaxiidae) dominated the Threatened and At Risk taxa. The majority (68%) belonged to the Galaxias genus, comprising 81% of recognised taxa in this genus and all five species in the genus Neochanna were also ranked as Threatened or At Risk. In addition to 51 native taxa, a further three fish species were considered colonists and 20 introduced species were classified as naturalised, although two of these are considered rare. The majority of the Threatened species occur in the Canterbury and Otago regions where a suite of rare non-migratory galaxiids exist. Threat mechanisms that were identified as causal in the decline of freshwater fish species were the impact of introduced fish species, declining water quality, effects of water abstraction, loss of habitat via land-use change and land-use activities, and river modifications. 相似文献
914.
N. Angusamy 《Marine Georesources & Geotechnology》2013,31(2):77-102
Exploration for placer deposits, especially for ilmenites, has been undertaken systematically in the southern coast of Tamil Nadu, India. On the basis of drainage network. Coastal landforms, lithology, and neotectonics, the study area has been grouped into five sectors: Mandapam, Valinokkam, Tuticorin, Manappad, and Kanyakumari. Ilmenites are abundant in Kanyakumari (Max. 53.39 wt%) and Tuticorin (Max. 20.88 wt%) sectors, negligible in Manappad (Max. 0.60 wt%) and Valinokkam (Max. 3.88 wt%) sectors and absent in the Mandapam sector. The abnormal enrichment of ilmenites in the Kanyakumari sector in the absence of any drainage network points to the possibility of a relict source. Literary and scientific evidence corroborates the existence of an Eastern Gondwana land called Lemuria, South of Kanyakumari which was later submerged in the Flandrian transgression. The association of other heavy minerals with ilmenites like overgrown and outgrown zircon supplements the idea of a longer stay of ilmenites in the depositional basin. Ilmenites from these fossil strandlines must have been reworked by the present day coastal processes and deposited in favorable bay-like NE-SW coastal configurations in Kanyakumari-Kuttankuli and Kallar-Vaippar regions under high energy wave conditions. The present study has disclosed the enrichment of ilmenites up to 1 m in depth in the above two zones which can be commercially exploited. The present study also calls for confirming part of the lost continent called Lemuria or Eastern Gondwana by systematic scientific investigations. 相似文献
915.
Radziminovich Ya. B. Filippova A. I. Gileva N. A. Melnikova V. I. 《Izvestiya Atmospheric and Oceanic Physics》2022,58(8):936-953
Izvestiya, Atmospheric and Oceanic Physics - We study in detail the source parameters, seismotectonic position, and macroseismic effects of the February 3, 2016, earthquake that occurred in the... 相似文献
916.
Zavyalov A. D. Morozov A. N. Aleshin I. M. Ivanov S. D. Kholodkov K. I. Pavlenko V. A. 《Izvestiya Atmospheric and Oceanic Physics》2022,58(8):908-924
Izvestiya, Atmospheric and Oceanic Physics - This paper is the first in a series of studies generalizing the Map of Expected Earthquakes (MEE) medium-term earthquake forecast method and analyzing... 相似文献
917.
Ananiev R. A. Dmitrevsky N. N. Roslyakov A. G. Chernykh D. V. Moroz E. A. Zarayskaya Y. A. Semiletov I. P. 《Oceanology》2022,62(1):127-132
Oceanology - The emission of natural gas from the seafloor to the surface in shelf areas of the Arctic seas is of increasing interest among researchers. Recently, various types of acoustic... 相似文献
918.
E. A. Agafonov N. A. Sorokina Yu. A. Prokhorenko E. E. Pavlova 《Physical Oceanography》1995,6(5):395-397
This paper discussesin situ observational data on the directed light attenuation index in the near-surface layer, collected in September 1987. The absolute light attenuation index has been evaluated for a near-shore strip of water 10–15 miles in width. When multidisciplinary research is conducted in the open sea, this part of the sea surface remains unstudied, as the observational grid for it is made larger than the spatial-temporal parameters of the biophysical processes producing optical inhomogeneities.Translated by Vladimir A. Puchkin. 相似文献
919.
920.
The investigation of the bottom of Lake Baikal carried out during the 2008 summer season by means of Mir manned deep-submergence
vehicles resulted in the recovery of a series of sediments, ferruginous crusts, and peculiar mineralized tubes several centimeters
high and up to 2–6 cm in diameter. According to the scanning electron investigation, these formations consist mainly of the
enclosing sediment particles and biogcnie silica cemented by iron and minor manganese hydroxides. The chemical composition
of the tubes is similar to both that of the enclosing sediments and slightly ferruginous crusts and nodules, but the tubes
and crusts are somewhat richer relative to the sediments in some microelements, namely, arsenic, cadmium, and uranium. In
general, the structure and composition of these tubes reminds one of the worm tubes common in the sediments of a number of
seas. The investigation of the rare earth elements in some samples or ferruginous formations and sediments revealed a positive
europium anomaly, which might be related to either the composition of the surrounding continental magmatic rocks or to the
influence of hypothetical hydrothermal solutions. 相似文献