Phytoplankton community in the Western Arctic in July–August 2003     

V. M. Sergeeva  I. N. Sukhanova  M. V. Flint  L. A. Pautova  J. M. Grebmeier  L. W. Cooper 《Oceanology》2010,50(2):184-197

The phytoplankton community was studied in Bering Strait and over the shelf, continental slope, and deep-water zones of the Chukchi and Beaufort seas in the middle of the vegetative season (July–August 2003). Its structure was analyzed in relation to ice conditions and the seasonal patterns of water warming, stratification, and nutrient concentrations. The overall ranges of variation in phytoplankton abundance and biomass were estimated at 2.0 × 10² to 6.0 × 10⁶ cells/l and 0.1 to 444.1 mg C/m³. The bulk of phytoplankton cells concentrated in the seasonal picnocline, at depths of 10–25 m. The highest values of cell density and biomass were recorded in regions influenced by the inflow of Bering Sea waters or characterized by intense hydrodynamics, such as the Bering Strait, Barrow Canyon, and the outer shelf and slope of the Chukchi Sea. In the middle of the vegetative season, the phytoplankton in the study region of the Western Arctic proved to comprise three successional (seasonal) assemblages, namely, the early spring, late spring, and summer assemblages. Their spatial distribution was dependent mainly on local features of hydrological and nutrient regimes rather than on general latitudinal trends of seasonal succession characteristic of arctic ecosystems.  相似文献   

Analcime: A characteristic authigenic phase of andean alluvium,northern chile     

Adrian Hartley  Stephen Flint  Peter Turner 《Geological Journal》1991,26(3):189-202

Analcime (NaAlSi₂O₆.H₂O) forms a characteristic authigenic phase in Andean alluvium of northern Chile. Three stratigraphic units ranging from the lower Cretaceous to the Miocene were studied in order to investigate the presence of analcime in diagenetic assemblages of different ages. The units were deposited in forearc, foreland/back-arc, and intra-arc basinal settings. Characteristics of other sedimentary analcime occurrences were examined in order to define conditions favourable for analcime precipitation. Zeolite zonation and evidence for the original presence of volcanic glass, common to many sedimentary analcime occurrences, are absent in the studied units. Analcime precipitation requires a high Na⁺/H⁺ ratio, relatively low Si⁴⁺/Al³⁺ activity and low H₂O activity. Diagenetic examination of the three stratigraphic units revealed early quartz and feldspar overgrowths, mechanical clay infiltration, and dissolution of labile rock and mineral fragments, particularly intermediate plagioclase (An_30–80). Conditions for these processes are favoured by oxidizing groundwater at near neutral pH. Later diagenesis involved the precipitation of analcime, non-ferroan calcite, quartz, and authigenic clays as the main cementing phases. These formed due to the concentration of oxidizing groundwater and resulted from its continued reaction with detrital feldspars and rock fragments of andesitic and dacitic composition. Analcime precipitation in Andean alluvium resulted from the evolution of saline, alkaline brines under an arid, evaporative climate in closed hydrographic basins with circulating groundwater systems.  相似文献   

Genetic Diversity of Copepod Limnocalanus macrurus from Russian Arctic Seas     

Gordeeva  N. V.  Drits  A. V.  Flint  M. V. 《Oceanology》2019,59(6):903-911

Oceanology - The diversity, phylogenetic relationships, and demographic history of glacial relict copepod Limnocalanus macrurus from estuaries of large Siberian Arctic rivers (the Ob, Khatanga,...  相似文献   

Trophic cascades and future harmful algal blooms within ice-free Arctic Seas north of Bering Strait: A simulation analysis     

John J. Walsh  Dwight A. Dieterle  F. Robert Chen  Jason M. Lenes  Wieslaw Maslowski  John J. Cassano  Terry E. Whitledge  Dean Stockwell  Mikhail Flint  Irina N. Sukhanova  John Christensen 《Progress in Oceanography》2011,91(3):312-343

Within larger ice-free regions of the western Arctic Seas, subject to ongoing trophic cascades induced by past overfishing, as well as to possible future eutrophication of the drainage basins of the Yukon and Mackenzie Rivers, prior very toxic harmful algal blooms (HABs) – first associated with ∼100 human deaths near Sitka, Alaska in 1799 – may soon expand. Blooms of calcareous coccolithophores in the Bering Sea during 1997–1998 were non-toxic harbingers of the subsequent increments of other non-siliceous phytoplankton. But, now saxitoxic dinoflagellates, e.g. Alexandrium tamarense, were instead found by us within the adjacent downstream Chukchi Sea during SBI cruises of 2002 and 2003. A previous complex, coupled biophysical model had been validated earlier by ship-board observations from the Chukchi/Beaufort Seas during the summer of 2002. With inclusion of phosphorus as another chemical state variable to modulate additional competition by recently observed nitrogen-fixers, we now explore here the possible consequences of altered composition of dominant phytoplankton functional groups [diatoms, microflagellates, prymnesiophyte Phaeocystis colonies, coccolithophores, diazotrophs, and dinoflagellates] in relation to increases of the toxic A. tamarense, responding to relaxation of grazing pressure by herbivores north of Bering Strait as part of a continuing trophic cascade. Model formulation was guided by validation observations obtained during 2002–2004 from: cruises of the SBI, CHINARE, and CASES programs; moored arrays in Bering Strait; other RUSALCA cruises around Wrangel Island; and SBI helicopter surveys of the shelf-break regions of the Arctic basin. Our year-long model scenarios during 2002–2003 indicate that post bloom silica-limitation of diatoms, after smaller simulated spring grazing losses, led to subsequent competitive advantages in summer for the coccolithophores, dinoflagellates, and diazotrophs. Immediate top-down control is exerted by imposed grazing pressures of the model’s herbivores and bottom-up control is also effected by light-, nitrate-, ammonium-, silicate-, and phosphate-modulated competition among the six functional groups of the simulated phytoplankton community. Similar to the history of the southern North Sea adjacent to the Rhine River, possible farming of northwestern Alaska and Canada, in conjunction with other human activities of ice retreat and overfishing, may lead to future exacerbations of poisonous phytoplankton. These potential killers include both toxic dinoflagellate and diazotroph HABs, deadly to terrestrial and marine mammals, as well as those of prymnesiophytes, some of which have already foamed beaches, while others have killed fishes of European waters.  相似文献   

Contaminants in molting long-tailed ducks and nesting common eiders in the Beaufort Sea     

Franson JC  Hollmén TE  Flint PL  Grand JB  Lanctot RB 《Marine pollution bulletin》2004,48(5-6):504-513

In 2000, we collected blood from long-tailed ducks (Clangula hyemalis) and blood and eggs from common eiders (Somateria mollissima) at near-shore islands in the vicinity of Prudhoe Bay, Alaska, and at a reference area east of Prudhoe Bay. Blood was analyzed for trace elements and egg contents were analyzed for trace elements, organochlorine pesticides, polychlorinated biphenyls, and polycyclic aromatic hydrocarbons. Except for Se (mean=36.1 microg/g dry weight (dw) in common eiders and 48.8 microg/g dw in long-tailed ducks), concentrations of trace elements in blood were low and, although several trace elements differed between areas, they were not consistently higher at one location. In long-tailed ducks, Se in blood was positively correlated with activities of two serum enzymes, suggestive of an adverse effect of increasing Se levels on the liver. Although common eiders had high Se concentrations in their blood, Se residues in eggs were low (mean=2.28 microg/g dw). Strontium and Ni were higher in eggs near Prudhoe Bay than at the reference area, but none of the other trace elements or organic contaminants in eggs differed between locations. Concentrations of Ca, Sr, Mg, and Ni differed among eggs having no visible development, early-stage embryos, or late-stage embryos. Residues of 4,4'-DDE, cis-nonachlor, dieldrin, hexachlorobenzene, oxychlordane, and trans-nonachlor were found in 100% of the common eider eggs, but at low concentrations (means of 2.35-7.45 microg/kg wet weight (ww)). The mean total PCB concentration in eggs was 15.12 microg/kg ww. Of PAHs tested for, residues of 1- and 2-methylnaphthalene and naphthalene were found in 100% of the eggs, at mean concentrations of 0.36-0.89 microg/kg ww.  相似文献   

Learning from the Pros: The Role of ISSRM,SNR, and IASNR in Our Careers     

Naomi Krogman  Carla Koons Trentelman  Joan Brehm  Courtney Flint 《社会与自然资源》2013,26(2):176-183

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Content and Composition of Organic Compounds in Suspended Particulate Matter and Bottom Sediments in the Kara Sea during the Period of Seasonal Ice Melting     

Nemirovskaya  I. A.  Flint  M. V.  Artemiev  V. A.  Khramtsova  A. V.  Khalikov  I. S. 《Doklady Earth Sciences》2021,498(1):392-397

Doklady Earth Sciences - The first data on the content of organic compounds (OCs), i.e., Corg, lipids, and hydrocarbons (aliphatic (AHCs) and polycyclic aromatic (PAHs)) in the suspended...  相似文献   

Distribution Patterns of Methane,Hydrogen, and Helium in the Water Column of the Kara Sea     

Obzhirov  A. I.  Polonik  N. S.  Ponomareva  A. L.  Vereshchagina  O. V.  Telegin  Yu. A.  Syrbu  N. S.  Flint  M. V. 《Oceanology》2021,61(6):881-891

Oceanology - Estimates of the content of dissolved methane, hydrogen, and helium in seawater of the Kara Sea were obtained. It was found that the methane concentration in the studied areas varied...  相似文献   

First Data on the Structure of Phytoplankton Communities of the East Siberian Sea     

Sukhanova  I. N.  Flint  M. V.  Fedodov  A. V.  Sakharova  E. G.  Makkaveev  P. N.  Polukhin  A. A.  Nedospasov  A. A.  Schuka  A. S. 《Oceanology》2021,61(6):909-929

Oceanology - Research on the structure of phytoplankton communities of the East Siberian Sea has been carried out during the 69th cruise of the research vessel Akademik Mstislav Keldysh within the...  相似文献   

Carbon Dioxide Flux at the Water–Air Boundary at the Continental Slope in the Kara Sea     

Polukhin  A. A.  Flint  M. V.  Belikov  I. B.  Gusak  G. V.  Kazakova  U. A.  Muravya  V. O.  Pankratova  N. V.  Pronina  Yu. O.  Skorokhod  A. I.  Chultsova  A. L.  Shchuka  A. S. 《Oceanology》2021,61(5):625-631

Oceanology - The values and direction of carbon dioxide flux in the area of the continental slope in the north of the Kara Sea (St. Anna Trough) are calculated based on field studies in 2020 within...  相似文献