An important yet still not well documented aspect of recent changes in the Arctic Ocean is associ... more An important yet still not well documented aspect of recent changes in the Arctic Ocean is associated with the advection of anomalous sub-Arctic Atlantic- and Pacific-origin waters and biota into the polar basins, a process which we refer to as borealization. Using a 37-year archive of observations (1981–2017) we demonstrate dramatically contrasting regional responses to atlantification (that part of borealization related to progression of anomalies from the Atlantic sector of sub-Arctic seas into the Arctic Ocean) and pacification (the counterpart of atlantification associated with influx of anomalous Pacific waters). Particularly, we show strong salinification of the upper Eurasian Basin since 2000, with attendant reductions in stratification, and potentially altered nutrient fluxes and primary production. These changes are closely related to upstream conditions. In contrast, pacification is strongly manifested in the Amerasian Basin by the anomalous influx of Pacific waters, crea...
ABSTRACT Knowledge about the general circulation on the shelf off northern Norway on a sufficient... more ABSTRACT Knowledge about the general circulation on the shelf off northern Norway on a sufficiently small scale to include the influence of the shelf topography has been achieved before, through field investigations. However, little is known about what controls the flow in this area on the small scale. The objective of this study was to find what possibly controls the flow, with special emphasis on shelf circulation and ocean-shelf exchange. Due to lack of sufficiently appropriate (small-scale, long-term) field data, an approach using a numerical model was adopted. Through model sensitivity experiments it was possible to study the effect of shelf topography and upwelling-favourable wind separately. Successful simulation of the general shelf circulation and vortex formations in agreement with field observations indicates that the model employed was performing realistically. There appears to be a strong correlation between the variation in the onshore flux in the Malangendypet trench and that in the along-shore wind component. The shelf topography seems to induce a complex wind-driven up-welling, with cross shelf trenches guiding the onshore flow. The shelf topography in combination with strong topographic steering appear to induce upwelling in areas where topographically steered currents leaving the shelf converse with the slope current.
ABSTRACT This paper reports estimates of trophic flows of carbon off the Galician coast from a 1D... more ABSTRACT This paper reports estimates of trophic flows of carbon off the Galician coast from a 1D ecological model, which are compared with field data from a two week Lagrangian drift experiment. The model consists of 9 biological components: nitrate, ammonium, >5μm phytoplankton, 20 μm), ciliates, fast sinking detritus and slow sinking detritus. Calculations were made for the fluxes of carbon between biological components within the upper 45m of the water column. The temporal development of primary production during the simulation period of two weeks was in good agreement with field estimates, which varied between 248 and 436mgC.m−2.d−1. Heterotrophic nanoflagellates had the greatest impact on carbon flux, with a grazing rate of 168mgC.m−2.d−1. Herbivorous grazing by microzooplankton amounted to 215mgC.m−2.d−1, whereas grazing by copepods on phytoplankton was 35mgC.m−2 d−1. Copepods grazing on microzooplankton was minor (0.47mgC.m−2.d−1) and the export flux from the upper 45m was 302mgC.m−2.d−1. Sensitivity analyses, in which the grazing parameters (i.e the functional relationship between ingestion and food concentration) were changed, were carried out on the heterotrophic dinoflagellate, ciliate and heterotrophic nanoflagellates/dinoflagellate components of the model. These changes did not alter the temporal development of heterotrophic nanoflagellates/dinoflagellates biomass significantly, but ciliates and heterotrophic dinoflagellates were more sensitive to variations in the grazing parameters. The overall conclusion from this modelling study is that the coupling between small phytoplankton and heterotrophic nanoflagellates was the quantitatively most important process controlling carbon flow in this region.
ABSTRACT A composite film modified electrode containing a Keggin-type heteropolyanion, H3(PMo12O4... more ABSTRACT A composite film modified electrode containing a Keggin-type heteropolyanion, H3(PMo12O40)⋅H2O, was fabricated with 3-aminopropyltrimethoxysilane (APMS) attached on an electrochemically activated glassy carbon (GC) electrode through the formation of COSi bond. PMo12O was then complexed with APMS through the electrostatic interaction between the phosphate groups of PMo12O and amine groups of APMS (PMo12O-APMS). XPS and cyclic voltammetry were employed for characterization of the composite film. The PMo12O-APMS modified electrode showed three reversible redox pairs with smaller peak-separation and was stable in the larger pH range compared with that in a solution phase. The catalytic properties of the modified electrode for the reduction of ClO, BrO, and IO were studied and the modified electrode exhibited good electrocatalytic activities for the three anions. The experimental parameters, such as pH, temperature, and the applied potential were optimized. The detection limits were determined to be 7.0±0.35 μM, 4.0±0.17 μM, and 0.1±0.04 μM for ClO, BrO, and IO , respectively. The modified electrode was applied to natural water samples for the detection of ClO, BrO, and IO.
The effect of oceanographic conditiond on disrtibution and population dynamics of commerical fish... more The effect of oceanographic conditiond on disrtibution and population dynamics of commerical fish stocks in the Barents Sea. Proceedings of the third Soviet-Norwegian Symposium. Murmansk, 26-28 May 1986.
An important yet still not well documented aspect of recent changes in the Arctic Ocean is associ... more An important yet still not well documented aspect of recent changes in the Arctic Ocean is associated with the advection of anomalous sub-Arctic Atlantic- and Pacific-origin waters and biota into the polar basins, a process which we refer to as borealization. Using a 37-year archive of observations (1981–2017) we demonstrate dramatically contrasting regional responses to atlantification (that part of borealization related to progression of anomalies from the Atlantic sector of sub-Arctic seas into the Arctic Ocean) and pacification (the counterpart of atlantification associated with influx of anomalous Pacific waters). Particularly, we show strong salinification of the upper Eurasian Basin since 2000, with attendant reductions in stratification, and potentially altered nutrient fluxes and primary production. These changes are closely related to upstream conditions. In contrast, pacification is strongly manifested in the Amerasian Basin by the anomalous influx of Pacific waters, crea...
ABSTRACT Knowledge about the general circulation on the shelf off northern Norway on a sufficient... more ABSTRACT Knowledge about the general circulation on the shelf off northern Norway on a sufficiently small scale to include the influence of the shelf topography has been achieved before, through field investigations. However, little is known about what controls the flow in this area on the small scale. The objective of this study was to find what possibly controls the flow, with special emphasis on shelf circulation and ocean-shelf exchange. Due to lack of sufficiently appropriate (small-scale, long-term) field data, an approach using a numerical model was adopted. Through model sensitivity experiments it was possible to study the effect of shelf topography and upwelling-favourable wind separately. Successful simulation of the general shelf circulation and vortex formations in agreement with field observations indicates that the model employed was performing realistically. There appears to be a strong correlation between the variation in the onshore flux in the Malangendypet trench and that in the along-shore wind component. The shelf topography seems to induce a complex wind-driven up-welling, with cross shelf trenches guiding the onshore flow. The shelf topography in combination with strong topographic steering appear to induce upwelling in areas where topographically steered currents leaving the shelf converse with the slope current.
ABSTRACT This paper reports estimates of trophic flows of carbon off the Galician coast from a 1D... more ABSTRACT This paper reports estimates of trophic flows of carbon off the Galician coast from a 1D ecological model, which are compared with field data from a two week Lagrangian drift experiment. The model consists of 9 biological components: nitrate, ammonium, >5μm phytoplankton, 20 μm), ciliates, fast sinking detritus and slow sinking detritus. Calculations were made for the fluxes of carbon between biological components within the upper 45m of the water column. The temporal development of primary production during the simulation period of two weeks was in good agreement with field estimates, which varied between 248 and 436mgC.m−2.d−1. Heterotrophic nanoflagellates had the greatest impact on carbon flux, with a grazing rate of 168mgC.m−2.d−1. Herbivorous grazing by microzooplankton amounted to 215mgC.m−2.d−1, whereas grazing by copepods on phytoplankton was 35mgC.m−2 d−1. Copepods grazing on microzooplankton was minor (0.47mgC.m−2.d−1) and the export flux from the upper 45m was 302mgC.m−2.d−1. Sensitivity analyses, in which the grazing parameters (i.e the functional relationship between ingestion and food concentration) were changed, were carried out on the heterotrophic dinoflagellate, ciliate and heterotrophic nanoflagellates/dinoflagellate components of the model. These changes did not alter the temporal development of heterotrophic nanoflagellates/dinoflagellates biomass significantly, but ciliates and heterotrophic dinoflagellates were more sensitive to variations in the grazing parameters. The overall conclusion from this modelling study is that the coupling between small phytoplankton and heterotrophic nanoflagellates was the quantitatively most important process controlling carbon flow in this region.
ABSTRACT A composite film modified electrode containing a Keggin-type heteropolyanion, H3(PMo12O4... more ABSTRACT A composite film modified electrode containing a Keggin-type heteropolyanion, H3(PMo12O40)⋅H2O, was fabricated with 3-aminopropyltrimethoxysilane (APMS) attached on an electrochemically activated glassy carbon (GC) electrode through the formation of COSi bond. PMo12O was then complexed with APMS through the electrostatic interaction between the phosphate groups of PMo12O and amine groups of APMS (PMo12O-APMS). XPS and cyclic voltammetry were employed for characterization of the composite film. The PMo12O-APMS modified electrode showed three reversible redox pairs with smaller peak-separation and was stable in the larger pH range compared with that in a solution phase. The catalytic properties of the modified electrode for the reduction of ClO, BrO, and IO were studied and the modified electrode exhibited good electrocatalytic activities for the three anions. The experimental parameters, such as pH, temperature, and the applied potential were optimized. The detection limits were determined to be 7.0±0.35 μM, 4.0±0.17 μM, and 0.1±0.04 μM for ClO, BrO, and IO , respectively. The modified electrode was applied to natural water samples for the detection of ClO, BrO, and IO.
The effect of oceanographic conditiond on disrtibution and population dynamics of commerical fish... more The effect of oceanographic conditiond on disrtibution and population dynamics of commerical fish stocks in the Barents Sea. Proceedings of the third Soviet-Norwegian Symposium. Murmansk, 26-28 May 1986.
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Papers by Dag Slagstad