Postglacial paleoceanography of Hudson Bay: stratigraphic, microfaunal, and palynological evidence

1990 ◽  
Vol 27 (7) ◽  
pp. 946-963 ◽  
Author(s):  
Guy Bilodeau ◽  
Anne de Vernal ◽  
Claude Hillaire-Marcel ◽  
Heiner Josenhans
Keyword(s):  
Surface Waters ◽  
Latitudinal Gradient ◽  
Water Mass ◽  
Water Masses ◽  
Hudson Bay ◽  
Marine Invasion ◽  
Arctic Conditions ◽  
Pollen And Spores ◽  
Abundance And Diversity ◽  
Lake Ojibway

Cores containing representative sequences of postglacial sediments in northern and southern Hudson Bay were analyzed for their microfaunal (foraminifers and ostracods) and palynological (dinocysts, pollen, and spores) content in order to reconstruct the evolution of environments since the last glaciation.In southern Hudson Bay, the marine invasion of the Tyrrell Sea at ca. 8000 BP, following the Lake Ojibway episode, was accompanied by the development of an Arctic-type microflora and microfauna indicative of a dense seasonal sea-ice cover and stratified water masses. Shortly after 8000 BP, the establishment of subarctic conditions in surface waters was accompanied by more intense homogenization of water masses. Subarctic conditions have persisted throughout most of the postglacial interval despite a recent surface-water cooling.In northern Hudson Bay, micropaleontological and lithological data reveal a succession of proximal to distal glaciomarine environments characterized by low biogenic productivity, harsh Arctic conditions, and stratified water masses. An increase in dinocyst abundance and diversity, after 6000 BP, indicates the establishment of cool subarctic conditions in surface waters, while foraminifer assemblages suggest intensified mixing of water masses.The micropaleontological records of northern and southern Hudson Bay reveal a strong latitudinal gradient in biogenic productivity and water mass characteristics throughout the postglacial interval. "Interglacial" conditions, established in southern Hudson Bay very shortly after it was invaded by the sea, seem to have occurred much later in northern Hudson Bay.

Contribution palynostratigraphique (dinokystes, pollen et spores) à la connaissance de la mer de Champlain: coupe de Saint-Césaire, Québec

1989 ◽  
Vol 26 (12) ◽  
pp. 2450-2464 ◽  
Author(s):  
Anne de Vernal ◽  
Claire Goyette ◽  
Cyril G. Rodrigues
Keyword(s):  
High Resolution ◽  
Relative Abundance ◽  
Surface Waters ◽  
Dinoflagellate Cysts ◽  
Site Location ◽  
Morphological Variations ◽  
Forest Tundra ◽  
Arctic Conditions ◽  
Shrub Tundra ◽  
Pollen And Spores

High-resolution continental (pollen and spores) and marine (dinoflagellate cysts) microfloral records were obtained from a section consisting of about 0.5 m of glaciolacustrine and 2.5 m of Champlain Sea deposits at the Saint-Césaire site. The pollen and spore assemblages indicate the existence of a regional open vegetation of shrub tundra to forest tundra. Fluctuations in the percentages of Picea and shrub and herb taxa are related to regional afforestation and paleogeographical evolution of the basin. The Champlain Sea sediments contain an abundant dinocyst flora dominated by Operculodinium centrocarpum, Brigantedinium spp., and Algidasphaeridium? minutum, which indicate cold Arctic conditions in surface waters. Fluctuations in concentration (102–104∙cm−3) and relative abundance of dinocyst species are attributed to changes in dinoflagellate productivity and paleoceanographic conditions, notably paleosalinity. Morphological variations of Operculodinium centrocarpum and Algidasphaeridium? minutum led to this description of the varieties, named "cezare" after the site location.

scholarly journals A New Characterization of the Upper Waters of the central Gulf of México based on Water Mass Hydrographic and Biogeochemical Characteristics

2019 ◽  
Author(s):  
Gabriela Yareli Cervantes-Diaz ◽  
Jose Martín Hernández-Ayón ◽  
Alberto Zirino ◽  
Sharon Zinah Herzka ◽  
Victor Camacho-Ibar ◽  
...  
Keyword(s):  
Surface Water ◽  
Gulf Of Mexico ◽  
Surface Waters ◽  
Water Mass ◽  
Biogeochemical Cycles ◽  
Water Masses ◽  
Near Surface ◽  
Deep Waters ◽  
Mesoscale Processes

Abstract. In the Gulf of Mexico (GoM) at least three near-surface water masses are affected by mesoscale processes that modulate the biogeochemical cycles. Prior studies have presented different classifications of water masses where the greater emphasis was on deep waters and not on the surface waters (σθ 

scholarly journals Tracing Water Mass Mixing From the Equatorial to the North Pacific Ocean With Dissolved Neodymium Isotopes and Concentrations

2021 ◽  
Vol 7 ◽  
Author(s):  
Michael Fuhr ◽  
Georgi Laukert ◽  
Yang Yu ◽  
Dirk Nürnberg ◽  
Martin Frank
Keyword(s):  
Pacific Ocean ◽  
Deep Water ◽  
Surface Waters ◽  
North Pacific ◽  
Water Mass ◽  
North Pacific Ocean ◽  
Water Masses ◽  
Intermediate Water ◽  
Nd Isotope ◽  
Geochemical Tracers

The sluggish water mass transport in the deeper North Pacific Ocean complicates the assessment of formation, spreading and mixing of surface, intermediate and deep-water masses based on standard hydrographic parameters alone. Geochemical tracers sensitive to water mass provenance and mixing allow to better characterize the origin and fate of the prevailing water masses. Here, we present dissolved neodymium (Nd) isotope compositions (εNd) and concentrations ([Nd]) obtained along a longitudinal transect at ∼180°E from ∼7°S to ∼50°N. The strongest contrast in Nd isotope signatures is observed in equatorial regions between surface waters (εNd ∼0 at 4.5°N) and Lower Circumpolar Deep Water (LCDW) prevailing at 4500 m depth (εNd = −6.7 at 7.2°N). The Nd isotope compositions of equatorial surface and subsurface waters are strongly influenced by regional inputs from the volcanic rocks surrounding the Pacific, which facilitates the identification of the source regions of these waters and seasonal changes in their advection along the equator. Highly radiogenic weathering inputs from Papua-New-Guinea control the εNd signature of the equatorial surface waters and strongly alter the εNd signal of Antarctic Intermediate Water (AAIW) by sea water-particle interactions leading to an εNd shift from −5.3 to −1.7 and an increase in [Nd] from 8.5 to 11.0 pmol/kg between 7°S and 15°N. Further north in the open North Pacific, mixing calculations based on εNd, [Nd] and salinity suggest that this modification of the AAIW composition has a strong impact on intermediate water εNd signatures of the entire region allowing for improved identification of the formation regions and pathways of North Pacific Intermediate Water (NPIW). The deep-water Nd isotope signatures indicate a southern Pacific origin and subsequent changes along its trajectory resulting from a combination of water mass mixing, vertical processes and Nd release from seafloor sediments, which precludes Nd isotopes as quantitative tracers of deep-water mass mixing. Moreover, comparison with previously reported data indicates that the Nd isotope signatures and concentrations below 100 m depth essentially remained stable over the past decades, which suggests constant impacts of water mass advection and mixing as well as of non-conservative vertical exchange and bottom release.

scholarly journals Analysis of specific water masses transports in the Western Mediterranean in the MEDRYS1V2 twenty-one-year reanalysis.

2020 ◽  
Author(s):  
Quentin-Boris Barral ◽  
Bruno Zakardjian ◽  
Franck Dumas ◽  
Pierre Garreau ◽  
Jonathan Beuvier
Keyword(s):  
Interannual Variability ◽  
Surface Waters ◽  
Seasonal Variability ◽  
Water Mass ◽  
Western Mediterranean ◽  
Water Masses ◽  
Potential Density ◽  
Ligurian Sea ◽  
Near Surface ◽  
Balearic Sea

<p>We present an analysis of specific water masses fluxes in the Western Mediterranean Sea issued from a twenty years (1992-2013) reanalysis (MEDRYS1V2). Water masses are identified on the base of salinity and potential density properties and computes; the fractions of each water mass involved in total flux are computed under the hypothesis assumptions of mixing lines schemes. It was first designed in order to avoid rough truncations between water masses on the T-S diagram when using fixed thermo-haline properties thresholds. The method does not use the temperature marker due to its high seasonal variability in near surface waters (0-200 m) and we consider that potential density is a better marker to discriminate deep and intermediate water masses. The algorithm discriminates successively five different water masses : the Atlantic Water (AW) incoming from the Gibraltar strait (salinity between 36,1 and 38,45 PSU), the Levantine Intermediate Waters (LIW) incoming from the Tunisia-Sicily strait (salinity between 38,45 and 39.1 PSU), the Modified Atlantic Waters (MAW) defined as near-surface waters (potential density less than 28,9 kg m-3) that are neither AW or LIW, while Western Intermediate Waters (WIW) are those remaining until the σθ = 29,10 kg m-3 threshold for Western Mediterranean Deep Waters (WMDW) is reached. Such computed fractions of each water mass, whose sum is constrained to unity, are then used to compute their water masses transports all along over twenty years of the reanalysis. The transport are assessed across computed on key transects delimiting known sub-basin entities (Ligurian Sea, Gulf of Lion, Balearic Sea...), with total transports showing balanced mass budget. The such computed total transport reveal marked differences in their seasonal to interannual variability, while the analysis of the water mass transports allows to identify those which mainly implied induced these variability. The results first show a low seasonal and no significant interannual variability at the exit of the Alboran Sea that results from the balance between the eastward AW/MAW outflow and the westward WIW and WMDW inflows. The Corsican strait, the Ligurian Sea line and Tunisia-Sardinia straits show a marked seasonal variability (0,37-0,39 Sv) mainly driven by the AW/MAW. By contrast, a strong interannual variability dominates the seasonal one (-2 to 1 Sv) between the Algerian Basin and the northern basin, correlated to the WMDW formation. The analysis of each specific water masses transport pointed out that shows this marked variability to be first driven by the intermediate and deep water masses transports. Similarly the interannual variability of the AW and MAW transports in the central part of the Western Mediterranean suggests some coupling between the deep, intermediate and surface water masses, even through the shallower Balearic Sea.</p>

scholarly journals Microplastics distribution in the Eurasian Arctic is affected by Atlantic waters and Siberian rivers

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Evgeniy Yakushev ◽  
Anna Gebruk ◽  
Alexander Osadchiev ◽  
Svetlana Pakhomova ◽  
Amy Lusher ◽  
...  
Keyword(s):  
Surface Water ◽  
Surface Waters ◽  
Water Masses ◽  
The Arctic ◽  
Plastic Pollution ◽  
Siberian River ◽  
Highest Weight ◽  
Surface Samples ◽  
Atlantic Origin ◽  
Type Size

AbstractPlastic pollution is globally recognised as a threat to marine ecosystems, habitats, and wildlife, and it has now reached remote locations such as the Arctic Ocean. Nevertheless, the distribution of microplastics in the Eurasian Arctic is particularly underreported. Here we present analyses of 60 subsurface pump water samples and 48 surface neuston net samples from the Eurasian Arctic with the goal to quantify and classify microplastics in relation to oceanographic conditions. In our study area, we found on average 0.004 items of microplastics per m3 in the surface samples, and 0.8 items per m3 in the subsurface samples. Microplastic characteristics differ significantly between Atlantic surface water, Polar surface water and discharge plumes of the Great Siberian Rivers, allowing identification of two sources of microplastic pollution (p < 0.05 for surface area, morphology, and polymer types). The highest weight concentration of microplastics was observed within surface waters of Atlantic origin. Siberian river discharge was identified as the second largest source. We conclude that these water masses govern the distribution of microplastics in the Eurasian Arctic. The microplastics properties (i.e. abundance, polymer type, size, weight concentrations) can be used for identification of the water masses.

scholarly journals Investigation of the abundance, distribution and composition of microplastics at coastal upwelling sites in the Atlantic Ocean

2016 ◽  
Author(s):  
La Daana K Kanhai ◽  
Rick Officer ◽  
Ian O'Connor ◽  
Richard C Thompson
Keyword(s):  
Atlantic Ocean ◽  
Surface Waters ◽  
Primary Productivity ◽  
Null Hypothesis ◽  
Latitudinal Gradient ◽  
Coastal Upwelling ◽  
Abundance Distribution ◽  
Significant Difference ◽  
Benguela Upwelling ◽  
Canary Upwelling

Microplastics are an issue of international concern due to the fact that these substances may potentially threaten biota by (i) causing physical harm, (ii) transporting persistent, bioaccumulating and toxic (PBT) substances and, (iii) leaching plastic additives. Within the world’s oceans, areas which experience coastal upwelling are biota rich due to their high levels of primary productivity. The assessment of microplastic presence in areas which experience coastal upwelling is vital as it will indicate whether microplastics are an issue of concern in areas which support key biological resources. The null hypothesis of the present study is that microplastic abundance will be lower in areas where there is upwelling. As such, the present study aims to investigate whether microplastic abundance in upwelled areas in the Atlantic Ocean is significantly different from non-upwelled areas. Based on an opportunistic voyage aboard the RV Polarstern, microplastics will be sampled in sub-surface waters along a diverse latitudinal gradient in the Atlantic Ocean i.e. from Bremerhaven (Germany) to Cape Town (South Africa). Based on the proposed route, it will be possible to determine microplastic levels at two areas of coastal upwelling in the Atlantic Ocean (i) Canary Upwelling Ecosystem (CUE) and (ii) Benguela Upwelling Ecosystem (BUE). The results will then be analysed to determine whether there was a statistically significant difference between ‘upwelled areas’ and ‘non-upwelled areas’.

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