scholarly journals Physical and remineralization processes govern the cobalt distribution in the deep western Atlantic ocean

2013 ◽  
Vol 10 (10) ◽  
pp. 15951-16001
Author(s):  
G. Dulaquais ◽  
M. Boye ◽  
M. J. A. Rijkenberg ◽  
X. Carton
Keyword(s):  
Atlantic Ocean ◽  
Large Scale ◽  
Vertical Diffusion ◽  
The West ◽  
Mixing Processes ◽  
Western Atlantic ◽  
North East ◽  
Deep Waters ◽  
Bottom Waters ◽  
High Concentrations

Abstract. The distributions of the bio-essential trace element dissolved Co (DCo) and the apparent particulate Co (PCo) are presented along the GEOTRACES-A02 deep section from 64° N to 50° S in the West Atlantic Ocean. PCo was determined as the difference between total cobalt (TCo, unfiltered samples) and DCo. DCo concentrations ranged from 14.7 pM to 94.3 pM, and PCo concentrations from undetectable values to 18.8 pM. The lowest DCo concentrations were observed in the subtropical domains, and the highest in the low-oxygenated Atlantic Central Waters (ACW) that appeared to be the major reservoir of DCo in the West Atlantic. In the Antarctic Bottom Waters, the enrichment in DCo with ageing of the water-mass can be related to suspension and redissolution of bottom sediments a well as diffusion of DCo from abyssal sediments. Mixing and dilution of deep water-masses, rather than scavenging of DCo onto settling particles, generated the meridional decrease of DCo along the southward large-scale circulation in the deep West Atlantic. Furthermore the apparent scavenged profile of DCo observed in the deep waters likely resulted from the persistence of relatively high concentrations in intermediate waters and low DCo concentrations in underlaying bottom waters. We suggested that the 2010 Icelandic volcanic eruption can be a source of DCo that could have been transported in the core of the North-East Atlantic Deep Waters. At intermediate depths, the high concentrations of DCo recorded in the ACW linearly correlated with the apparent utilization of oxygen (AOU), indicating that remineralization of DCo can be significant (representing up to 29% of the DCo present). Furthermore the preferential remineralization of phosphate (P) compared to Co in these low-oxygenated waters suggested a decoupling between the deep cycles of P and Co. The vertical diffusion of DCo from the ACW appeared to be a significant source of DCo into the surface waters of the equatorial domain. Summarizing the dilution and mixing processes rather than scavenging of DCo, and the remineralization can be the two major pathways controlling the cycling of DCo in the intermediate and deep West Atlantic.

scholarly journals Physical and remineralization processes govern the cobalt distribution in the deep western Atlantic Ocean

2014 ◽  
Vol 11 (6) ◽  
pp. 1561-1580 ◽  
Author(s):  
G. Dulaquais ◽  
M. Boye ◽  
M. J. A. Rijkenberg ◽  
X. Carton
Keyword(s):  
Atlantic Ocean ◽  
Large Scale ◽  
Vertical Diffusion ◽  
Mixing Processes ◽  
Western Atlantic ◽  
Western Atlantic Ocean ◽  
Deep Waters ◽  
Bottom Waters ◽  
The Difference ◽  
High Concentrations

Abstract. The distributions of the bio-essential trace element dissolved cobalt (DCo) and the apparent particulate Co (PCo) are presented along the GEOTRACES-A02 deep section from 64° N to 50° S in the western Atlantic Ocean (longest section of international GEOTRACES marine environment program). PCo was determined as the difference between total cobalt (TCo, unfiltered samples) and DCo. DCo concentrations ranged from 14.7 pM to 94.3 pM, and PCo concentrations from undetectable values to 18.8 pM. The lowest DCo concentrations were observed in the subtropical domains, and the highest in the low-oxygenated Atlantic Central Waters (ACW), which appears to be the major reservoir of DCo in the western Atlantic. In the Antarctic Bottom Waters, the enrichment in DCo with aging of the water mass can be related to suspension and redissolution of bottom sediments a well as diffusion of DCo from abyssal sediments. Mixing and dilution of deep water masses, rather than scavenging of DCo onto settling particles, generated the meridional decrease of DCo along the southward large-scale circulation in the deep western Atlantic. Furthermore, the apparent scavenged profile of DCo observed in the deep waters likely resulted from the persistence of relatively high concentrations in intermediate waters and low DCo concentrations in underlaying bottom waters. We suggest that the 2010 Icelandic volcanic eruption could have been a source of DCo that could have been transported into the core of the Northeast Atlantic Deep Waters. At intermediate depths, the high concentrations of DCo recorded in the ACW linearly correlated with the apparent utilization of oxygen (AOU), indicating that remineralization of DCo could be significant (representing up to 37% of the DCo present). Furthermore, the preferential remineralization of phosphate (P) compared to Co in these low-oxygenated waters suggests a decoupling between the deep cycles of P and Co. The vertical diffusion of DCo from the ACW appears to be a significant source of DCo into the surface waters of the equatorial domain. Summarizing, the dilution due to mixing processes rather than scavenging of DCo and the above-mentioned remineralization could be the two major pathways controlling the cycling of DCo into the intermediate and deep western Atlantic.

Large-scale distribution of coccolithophores and Parmales in the surface waters of the Atlantic Ocean

2016 ◽  
Vol 98 (3) ◽  
pp. 567-579 ◽  
Author(s):  
Qingshan Luan ◽  
Jianqiang Sun ◽  
Jun Wang
Keyword(s):  
Atlantic Ocean ◽  
Southern Ocean ◽  
Surface Waters ◽  
Large Scale ◽  
Close Association ◽  
Polar Front ◽  
Falkland Islands ◽  
North East ◽  
Algal Groups ◽  
Latitudinal Patterns

Coccolithophores and Parmales are important functional groups of calcified and siliceous marine nanophytoplankton. Large-scale biogeographic distributions of the two groups were investigated based on 71 samples that were collected in the Atlantic Ocean. Using a scanning electron microscope, a total of 48 taxa of coccolithophores and eight taxa of Parmales were recorded, with Emiliania huxleyi, Tetraparma pelagica and Triparma strigata as the predominant forms. The highest abundances of coccolithophores (376 × 103 cells l−1) and Parmales (624 × 103 cells l−1) were observed in waters north-east of the Falkland Islands and the South Georgia Island, in close association with the Subantarctic Front and Polar Front, respectively. Three major biogeographic assemblages, i.e. the Falkland Shelf Assemblage, the Southern Ocean Assemblage and the Atlantic Ocean Assemblage, were revealed in cluster analysis. Additionally, canonical correspondence analysis indicated that temperature significantly affects the latitudinal patterns of the two algal groups. High abundances of Parmales were closely coupled with those of E. huxleyi in waters of the Southern Ocean with low temperature (<10°C). However, the number of coccolithophore species, along with the Shannon–Weaver diversity, significantly increased with elevated temperature, suggesting more diverse assemblages in tropical waters.

Combined effects of cadmium and salinity on development and survival of flounder eggs

1975 ◽  
Vol 55 (4) ◽  
pp. 945-957 ◽  
Author(s):  
H. Von Westernhagen ◽  
V. Dethlefsen
Keyword(s):  
Heavy Metals ◽  
Atlantic Ocean ◽  
Sea Water ◽  
Cadmium Concentration ◽  
South Atlantic Ocean ◽  
Combined Effects ◽  
East Atlantic ◽  
The West ◽  
North East ◽  
The North

Like most heavy metals, cadmium is only found in minute amounts in natural sea water. Krauskopf (1956) stated that cadmium concentration of normal sea water ranges from 0.032 to 0.075 PPb (μg/l−1) while Goldberg (1965) gave a somewhat higher value of 0.11 ppb. Cadmium concentrations determined by Preston (1973) for the North-East Atlantic Ocean range from <0.01 to 0.41 ppb, and similar values have been found by Windom & Smith (1972) in the West- and Chester & Stoner (1974) in the South Atlantic Ocean (0.04–0.17 ppb).

Multispecies and Watershed Approaches to Freshwater Fish Conservation

2019 ◽  
Keyword(s):  
Coal Mining ◽  
Large Scale ◽  
Mine Drainage ◽  
Aquatic Organisms ◽  
The United States ◽  
Lessons Learned ◽  
The West ◽  
River Watershed ◽  
Susquehanna River ◽  
High Concentrations

<em>Abstract</em>.—Historic coal mining operations throughout the United States left behind a legacy of waterways polluted by abandoned mine drainage (AMD). Streams polluted by AMD typically have low pH and high concentrations of heavy metals such as aluminum, iron, and manganese, creating toxic environments for aquatic organisms and causing many of these environments to be devoid of aquatic life. This chapter details the large-scale restoration efforts underway since 2004 in the West Branch Susquehanna River watershed in north-central Pennsylvania to remediate AMD. It provides an overview of the historical coal mining throughout the watershed and the types of restoration projects that have been completed. The importance of establishing and maintaining partnerships for large-scale restoration projects is emphasized along with a discussion on how these projects have been monitored and maintained to ensure restoration success. This chapter aims to provide guidance in the development of other large-scale restoration projects through the lessons learned over the past 15 years of restoration in the West Branch Susquehanna River watershed.

scholarly journals Size class segregation of Arctic cod (Boreogadus saida) in a shallow High Arctic embayment

2020 ◽  
pp. 1-9
Author(s):  
S.T. Kessel ◽  
R.E. Crawford ◽  
N.E. Hussey ◽  
S.V. Ivanova ◽  
J.P. Holden ◽  
...  
Keyword(s):  
Geographic Area ◽  
High Arctic ◽  
Size Class ◽  
Boreogadus Saida ◽  
Size Segregation ◽  
The West ◽  
West Side ◽  
Arctic Cod ◽  
Deep Waters ◽  
High Concentrations

Arctic cod (Boreogadus saida (Lepechin, 1774)) vertically segregate by size class in deep waters, but such dynamics had not been explored in shallow waters. Spatial distribution of Arctic cod was investigated in Resolute Bay, Nunavut, Canada (74°41N, 94°52W) from 20 July to 5 August 2012, using a combination of hydroacoustic survey and direct capture. Hydroacoustic surveys identified two high concentrations of Arctic cod, with larger individuals detected on the west side, and smaller individuals on the east. Catch data confirmed size segregation, with fish sampled on the west side of the bay significantly larger (mean = 174 mm total length (TL); 35.9 g weight (WT)) than those on the east (mean = 110 mm TL; 9.2 g WT). Fish density on the west was estimated at 3.52 fish·m−2, extrapolated to the full 0.52 km2 of the surveyed shoal to ∼1 830 400 fish and 65 711 kg (assuming a 35.9 g mean WT). Smaller fish on the east side were more abundant (9.32 fish·m−2; total abundance ∼11 836 400 fish or 108 894 kg; mean WT = 9.2 g). Horizontal habitat-partitioning was observed between Arctic cod size classes over a small geographic area (∼8 km2), most probably due to partitioned resources and to mitigate predation risk.

Polyphyly and cryptic diversity in the hydrozoan families Lafoeidae and Hebellidae (Cnidaria:Hydrozoa)

2011 ◽  
Vol 25 (5) ◽  
pp. 454 ◽  
Author(s):  
Carlos J. Moura ◽  
Marina R. Cunha ◽  
Filipe M. Porteiro ◽  
Alex D. Rogers
Keyword(s):  
Cryptic Species ◽  
Large Scale ◽  
Morphological Characters ◽  
Distribution Data ◽  
Nominal Species ◽  
Cryptic Diversity ◽  
Phylogenetic Relations ◽  
North East ◽  
The North ◽  
Deep Waters

The taxonomy of the putative superfamily Lafoeoidea (Hydrozoa), which includes the families Hebellidae and Lafoeidae, has been widely disputed at all systematic levels, mainly because these are morphologically simple and plastic animals. We used the molecular marker 16S mRNA to address phylogenetic relations of ‘Lafoeoidea’ hydroids mainly from shallow and deep waters of the north-east Atlantic and west Mediterranean. This study proves that the morphological simplicity of the ‘Lafoeoidea’ has led to several erroneous taxonomic assignments. We demonstrate that the superfamily ‘Lafoeoidea’ is not monophyletic and thus not valid; the families Hebellidae and Lafoeidae are polyphyletic. The ‘Lafoeidae’ subfamilies ‘Lafoeinae’ and ‘Zygophylacinae’ were recovered as monophyletic but quite distantly related and should be erected to the level of distinct families. The 16S haplotype data analysed in conjunction with morphological characters and distribution data were useful in differentiating morphologically undistinguishable, nominal and cryptic or pseudo-cryptic species, including undescribed taxa. Particularly within the ‘Lafoeinae’ group, unexpectedly high genetic biodiversity (including cryptic species) was encountered in the possibly not monophyletic genera Lafoea, Acryptolaria and Filellum. Cryptic diversity is also likely associated with the ‘Zygophylacinae’ nominal species Cryptolaria pectinata. The indications of genetic segregation by geographical distance of the ‘Lafoeoidea’ hydroids, particularly verified in deep waters, is probably a consequence of their reduced potential for large-scale dispersal, which likely interacts with the influence of the seabed topography, oceanographic circulation and adaptability to tolerate different abiotic conditions.

Identification of N-Substituted Triazolo-azetidines as Novel Antibacterials using pDualrep2 HTS Platform

2019 ◽  
Vol 22 (5) ◽  
pp. 346-354
Author(s):  
Yan A. Ivanenkov ◽  
Renat S. Yamidanov ◽  
Ilya A. Osterman ◽  
Petr V. Sergiev ◽  
Vladimir A. Aladinskiy ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Large Scale ◽  
Underlying Mechanism ◽  
Luciferase Assay ◽  
Reporter System ◽  
E Coli ◽  
Starting Point ◽  
High Concentrations ◽  
Mic Value

Aim and Objective: Antibiotic resistance is a serious constraint to the development of new effective antibacterials. Therefore, the discovery of the new antibacterials remains one of the main challenges in modern medicinal chemistry. This study was undertaken to identify novel molecules with antibacterial activity. Materials and Methods: Using our unique double-reporter system, in-house large-scale HTS campaign was conducted for the identification of antibacterial potency of small-molecule compounds. The construction allows us to visually assess the underlying mechanism of action. After the initial HTS and rescreen procedure, luciferase assay, C14-test, determination of MIC value and PrestoBlue test were carried out. Results: HTS rounds and rescreen campaign have revealed the antibacterial activity of a series of Nsubstituted triazolo-azetidines and their isosteric derivatives that has not been reported previously. Primary hit-molecule demonstrated a MIC value of 12.5 µg/mL against E. coli Δ tolC with signs of translation blockage and no SOS-response. Translation inhibition (26%, luciferase assay) was achieved at high concentrations up to 160 µg/mL, while no activity was found using C14-test. The compound did not demonstrate cytotoxicity in the PrestoBlue assay against a panel of eukaryotic cells. Within a series of direct structural analogues bearing the same or bioisosteric scaffold, compound 2 was found to have an improved antibacterial potency (MIC=6.25 µg/mL) close to Erythromycin (MIC=2.5-5 µg/mL) against the same strain. In contrast to the parent hit, this compound was more active and selective, and provided a robust IP position. Conclusion: N-substituted triazolo-azetidine scaffold may be used as a versatile starting point for the development of novel active and selective antibacterial compounds.

MODELING THE SOUTH ATLANTIC OCEAN FROM MEDIUM TO HIGH RESOLUTION

2014 ◽  
Vol 31 (2) ◽  
Author(s):  
Mariela Gabioux ◽  
Vladimir Santos da Costa ◽  
Joao Marcos Azevedo Correia de Souza ◽  
Bruna Faria de Oliveira ◽  
Afonso De Moraes Paiva
Keyword(s):  
High Resolution ◽  
Atlantic Ocean ◽  
Large Scale ◽  
South Atlantic ◽  
Surface Relaxation ◽  
The South ◽  
Small Surface ◽  
Basic Model ◽  
Basic Set ◽  
Set Up

Results of the basic model configuration of the REMO project, a Brazilian approach towards operational oceanography, are discussed. This configuration consists basically of a high-resolution eddy-resolving, 1/12 degree model for the Metarea V, nested in a medium-resolution eddy-permitting, 1/4 degree model of the Atlantic Ocean. These simulations performed with HYCOM model, aim for: a) creating a basic set-up for implementation of assimilation techniques leading to ocean prediction; b) the development of hydrodynamics bases for environmental studies; c) providing boundary conditions for regional domains with increased resolution. The 1/4 degree simulation was able to simulate realistic equatorial and south Atlantic large scale circulation, both the wind-driven and the thermohaline components. The high resolution simulation was able to generate mesoscale and represent well the variability pattern within the Metarea V domain. The BC mean transport values were well represented in the southwestern region (between Vitória-Trinidade sea mount and 29S), in contrast to higher latitudes (higher than 30S) where it was slightly underestimated. Important issues for the simulation of the South Atlantic with high resolution are discussed, like the ideal place for boundaries, improvements in the bathymetric representation and the control of bias SST, by the introducing of a small surface relaxation. In order to make a preliminary assessment of the model behavior when submitted to data assimilation, the Cooper & Haines (1996) method was used to extrapolate SSH anomalies fields to deeper layers every 7 days, with encouraging results.

DESIGN AND IMPLEMENTATION OF THE OCEANOGRAPHIC MODELING AND OBSERVATION NETWORK (REMO) FOR PHYSICAL OCEANOGRAPHY STUDIES AND OCEAN FORECASTING

2014 ◽  
Vol 31 (2) ◽  
Author(s):  
Jose Antonio Moreira Lima
Keyword(s):  
Atlantic Ocean ◽  
Large Scale ◽  
North Pacific Ocean ◽  
Integrated Approach ◽  
Sea Surface ◽  
Global Ocean ◽  
Height Anomaly ◽  
The North ◽  
Observation Network ◽  
Ocean Forecasting

This paper is concerned with the planning, implementation and some results of the Oceanographic Modeling and Observation Network, named REMO, for Brazilian regional waters. Ocean forecasting has been an important scientific issue over the last decade due to studies related to climate change as well as applications related to short-range oceanic forecasts. The South Atlantic Ocean has a deficit of oceanographic measurements when compared to other ocean basins such as the North Atlantic Ocean and the North Pacific Ocean. It is a challenge to design an ocean forecasting system for a region with poor observational coverage of in-situ data. Fortunately, most ocean forecasting systems heavily rely on the assimilation of surface fields such as sea surface height anomaly (SSHA) or sea surface temperature (SST), acquired by environmental satellites, that can accurately provide information that constrain major surface current systems and their mesoscale activity. An integrated approach is proposed here in which the large scale circulation in the Atlantic Ocean is modeled in a first step, and gradually nested into higher resolution regional models that are able to resolve important processes such as the Brazil Current and associated mesoscale variability, continental shelf waves, local and remote wind forcing, and others. This article presents the overall strategy to develop the models using a network of Brazilian institutions and their related expertise along with international collaboration. This work has some similarity with goals of the international project Global Ocean Data Assimilation Experiment OceanView (GODAE OceanView).

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