Change search
Refine search result
1 - 5 of 5
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Andersson, Lars
    SMHI, Core Services.
    Trends in nutrient and oxygen concentrations in the Skagerrak-Kattegat1996In: Journal of Sea Research, ISSN 1385-1101, E-ISSN 1873-1414, Vol. 35, no 1-3, p. 63-71Article in journal (Refereed)
    Abstract [en]

    The Skagerrak and Kattegat form a transition zone between the Baltic and the North Sea. Both areas are subject to increased nutrient loads. In this paper a non-parametric method is used to calculate the changes in nutrient and oxygen concentrations in the area. The period chosen was 1971 to 1990 and the parameters were dissolved inorganic nitrogen, phosphorus, silicate, total nitrogen and total phosphorus together with oxygen and oxygen saturation. Data have been sorted after salinity and the analyses have been carried out for different water masses and subareas. The results demonstrate that both surface and deep water in the Kattegat show increasing trends during winter for all nutrients except silicate. During summer there is an increase in total nitrogen and total phosphorus while silicate shows a decrease. In the Skagerrak the picture is more variable; in the eastern part, however, there is a clear increase for all inorganic nutrients during winter in the coastal water. Oxygen shows a declining trend in most areas.

  • 2. Danielsson, A.
    et al.
    Jönsson, Anette
    SMHI, Core Services.
    Rahm, Lars
    SMHI, Research Department, Oceanography.
    Resuspension patterns in the Baltic proper2007In: Journal of Sea Research, ISSN 1385-1101, E-ISSN 1873-1414, Vol. 57, no 4, p. 257-269Article in journal (Refereed)
    Abstract [en]

    Waves induce resuspension of surface sediments and contribute to the long-term mobilisation of particulate matter from erosion to accumulation bottoms. This has a major impact on the nutrient cycle in shallow seas by enhancing degradation, microbial production and recycling. The Baltic Sea represents such an area. The aim of this work is to analyse the spatial and temporal resuspension patterns in the Baltic Sea. To estimate the bottom friction velocity, modelled wave data are used in combination with data on grain size. This new data set is compared to a resuspension threshold of friction velocity to estimate the events of resuspension. The variation in bottom friction velocity, resuspension frequency and duration are related to wind climate, fetch, water depth and sediment type. Substantial resuspension can be found down to 40-60 m, with durations from one day to as much as two weeks. The highest winds in the area are highly anisotropic with a dominance of S-SW-W winds and the highest resuspension frequencies are found along the shallow eastern coasts. A seasonal pattern is observed with relatively high friction velocities and high resuspension frequencies during winter. There is also a variation depending on grain size, where sediments with fine and medium sand have a considerably higher percentage of resuspension events than bottoms with other dominant grain sizes. Five sub-areas are identified, characterised by different sediment types, resuspension and wind characteristics. If, in the future, wind speed increases as predicted, resuspension of sediments will also increase with effects on the nutrient cycle. (c) 2006 Elsevier B.V. All rights reserved.

  • 3.
    Fonselius, Stig
    et al.
    SMHI, Research Department, Oceanography.
    Valderrama, Jorge
    SMHI, Research Department, Oceanography.
    One hundred years of hydrographic measurements in the Baltic Sea2003In: Journal of Sea Research, ISSN 1385-1101, E-ISSN 1873-1414, Vol. 49, no 4, p. 229-241Article in journal (Refereed)
    Abstract [en]

    The first measurements of salinity of the deep water in the open Baltic Sea were made in the last decades of the 1800s. At a Scandinavian science meeting in Copenhagen in 1892, Professor Otto Pettersson from Sweden suggested that regular measurements of hydrographic parameters should be carried out at some important deep stations in the Baltic Sea. His suggestion was adopted and since that time we have rather complete hydrographical data from the Bornholm Deep, the Gotland Deep, and the Landsort Deep and from some stations in the Gulf of Bothnia. The measurements were interrupted in the Baltic Proper during the two World Wars. At the beginning only salinity, temperature and dissolved oxygen were measured and one or two expeditions were carried out annually, mostly in summer. In the 1920s also alkalinity and pH were occasionally measured and total carbonate was calculated. A few nutrient measurements were also carried out. After World War 11 we find results from four or more expeditions every year and intercalibration of methods was arranged. Results of temperature, salinity and dissolved oxygen measurements from the Bornholm. Deep, the Gotland Deep, the Landsort Deep and salinity measurements from three stations in the Gulf of Bothnia, covering the whole 20th century are presented and discussed. The salinity distribution and the variations between oxygen and hydrogen sulphide periods in the deep water of the Gotland Deep and the Landsort Deep are demonstrated. Series of phosphate and nitrate distribution in the Gotland Deep are shown from the 1950s to the present and the effects of the stagnant conditions are briefly discussed. Two large inflows of highly saline water, the first during the First World War and the second in 195 1, are demonstrated. The 20th century minimum salinity of the bottom water in the Baltic Proper in 1992 is discussed. (C) 2003 Published by Elsevier Science B.V.

  • 4.
    Karlson, Bengt
    et al.
    SMHI, Research Department, Oceanography.
    Edler, Lars
    SMHI, Research Department, Oceanography.
    Graneli, W
    Sahlsten, Elisabeth
    SMHI, Research Department, Oceanography.
    Kuylenstierna, M
    Subsurface chlorophyll maxima in the Skagerrak - Processes and plankton community structure1996In: Journal of Sea Research, ISSN 1385-1101, E-ISSN 1873-1414, Vol. 35, no 1-3, p. 139-158Article in journal (Refereed)
    Abstract [en]

    Subsurface chlorophyll maxima are common phenomena in both the coastal and open ocean. The main objective of this study was to clarify possible differences in the structure and function of the plankton community in subsurface chlorophyll maxima and at the surface. Sampling was performed at seven stations in the Skagerrak, northeast Atlantic, during five cruises in May and August 1992 and April, May and August 1993. Subsurface chlorophyll fluorescence maxima (FM) occurred on 25 out of 32 sampling occasions. The FMs were usually situated below the pycnocline and associated with the nutricline. The ratio of chlorophyll a to particulate carbon and the light-saturated primary production were higher for plankton at the FM than at the surface, although assimilation numbers (primary production rate:chlorophyll a) were not different from surface plankton. The light protective pigment diadinoxanthin occurred in higher concentrations relative to chlorophyll a in surface plankton than in FM plankton. Respiration was higher in the FM than at the surface. This was not related to abundance of bacteria or bacterial production since no differences between surface and FM values were detected for these parameters. FM plankton was characterized by high nutrient uptake rates, but in this study there were no significant differences compared to surface plankton. 'New' production was on average 25%, but up to about 50% in the western Skagerrak in spring. The average nitrogen uptake rates were dominated by the regenerated nutrients ammonium and urea, accounting for about 50 and 25%, respectively. The <3 mu m size fraction contributed significantly to concentrations of total chlorophyll a, particulate carbon, and nitrogen as well as to nitrogen uptake. Its contribution was highest when total values were low. Microscopical investigations and analysis of pigments specific to algal groups showed that diatoms dominated in the FMs in spring and that peridinin-containing dinoflagellates dominated in FMs in August. Autotrophic nanoplankton was dominated by the Prymnesiophyceae contributing about 50% of total cell numbers. Colonies of Phaeocystis sp. were abundant along the NW Danish coast in April and May 1993, Autotrophic eukaryotic picoplankton occurred in cell numbers up to about 30 x 10(6) cells . dm(-3) along the Swedish coast. The highest cell numbers of cyanobacteria of the Synechococcus-type, about 100 x 10(6) cells . dm(-3), were found in the central Skagerrak in August and the abundance of Synechococcus was correlated with nitrogen uptake in the <3 mu m size fraction.

  • 5. Rydberg, Lars
    et al.
    Aertebjerg, Gunni
    Edler, Lars
    SMHI, Research Department, Oceanography.
    Fifty years of primary production measurements in the Baltic entrance region, trends and variability in relation to land-based input of nutrients2006In: Journal of Sea Research, ISSN 1385-1101, E-ISSN 1873-1414, Vol. 56, no 1, p. 1-16Article in journal (Refereed)
    Abstract [en]

    Inter-annual variations and long-term trends in phytoplankton primary production (PP) within the Baltic entrance region (the Kattegat and the Belt Sea) are presented and discussed. The study employs the core of Danish monitoring data, with measurements at 6-8 different sites from the past 20-50 years. Temporal development of the annual PP is compared with changes and variations in the land-based nutrient inputs and to other, independent, Swedish and Danish PP data. Spatial and seasonal variations based on annual and monthly PP, respectively, are evaluated. There are large variations on all scales; annual PP ranges from 50 to 500 g C m(-2), with maximum values in some Danish fjords and minimum values in open waters during the 1950s. The Kattegat and the Sound have a lower mean production (135-165 g C m(-2); 1981-2000) than the Great and Little Belts (185-220 g C m(-2)). Compared to 1950s and 1960s, the daily PP has changed from being almost constant between March and October, to having two more distinct maxima, one in March and one between July and September. It is obvious that annual mean production has increased considerably since the 1950s, but also that this increase took place before 1980. For data after 1980, we find a co-variation between annual nutrient loads and regional mean PP; years of low total nitrogen (TN) and total phosphorus (TP) input to the region coincide with low PP and vice versa. Waste-water treatment and measures in agriculture have reduced the land-based input of TN by about 1/3 and input of TP by about 2/3 since the 1980s, enough to cause a substantial decrease in the surface water nutrient concentrations. A simultaneous, but weak downward trend in the regional mean PP can be seen up to 1997, after which the trend is broken. Higher production from 1998 is most likely an effect of changes in the method used for determination of PP. (c) 2006 Elsevier B.V. All rights reserved.

1 - 5 of 5
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
v. 2.35.7
|