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Data Presentation



Data - Results - Quality

The following two figures represent the annual time series of daily means for nitrate/nitrite and phosphate from 1998 to 2002, measured at station DEUTSCHE BUCHT. Each daily mean was calculated from at least 15 measurements.
The annual time series for 1998, 1999 and 2000 were generated during the research project CANVAS. The data for 2001 and 2002 were determined within the SAMSON project and describe almost completly the annual course of nutrient concentrations. Seasonal events - such as the winter plateau, the nutrient depletion during the spring bloom or the nutrient accumulation in autumn by terrestrial drainage with the accompanied consumption during the autumn bloom - can be identified and evaluated in detail.

Nitrate daily mean values 1998 to 2002 Deutsche Bucht
  Phosphate daily mean values 1998 to 2002 Deutsche Bucht

meteorological, hydrographical and chemical  parameters are presented for the period 15.-21. November 2001 Fehmarn Belt  



Owing to the high temporal resolution of the
nutrient measurements at the MARNET-stations,
short-term processes
can be localized as well.
An example is shown in the left figure,
where meteorological, hydrographical and chemical
parameters are represented for the period
15.-21. November 2001. The data were
determined at the station FEHMARN BELT.
A low pressure area moved within 24 hours
eastwards over the Belt Sea, which resulted
in decreasing wind speed and changing wind
direction by 360 degrees. This led to an
increasing outward flow of Baltic Sea water
with lower salt content and higher nutrient
concentrations (accumulated by terrestrial drainage)
in northwestern direction through the Belt Sea.







Automatic Nutrient Analyser (see: Technology)
  • maintenance of the devices after each operating period
    •   baseline-test to control the mechanical and optical stability of the devices
  • calibration and recalibration before and after each operating period, respectively
    •   six equidistant concentration levels, each measured in four replicates
    •   use of adapted matrix for the standard solutions: low nutrient sea water for North Sea Baltic Sea
    •   optimised calibration ranges considering seasonally different nutrient concentrations in sea water
  • quality control
    •   checking the long-term stability of the reagents and devices
    •   validation of the analytical methods, including the determination analytical characteristics such as limits of detection and quantification, procedural standard deviation, homogeneity of variances etc.
    •   comparitive studies by other analytical methode

calibration range

DIN 32645 -
blank method
phosphate µmol/L nitrate/nitrite µmol/L silicate µmol/L

limits of detection




calibration range: summer




calibration range: winter




limits of quantification




calibration range: summer




calibration range: Winter





Comperative measurements for phosphate by automatic nutrient analyser Figures:
Comperative measurements for phosphate, nitrate/nitrite
and silicate by automatic nutrient analyser (APP) and
Segmented-Flow-Analyser (SFA)

The analyses were carried out within several monitoring
cruises in North Sea and Baltic Sea on bord the research
vessel GAUSS.

Comperative measurements for nitrate/nitrite by automatic nutrient analyser Comperative measurements for silicate by automatic nutrient analyser

Analytical Quality Control

Automatic Sampler for Organic Micropollutants (EPOS, see: Technology)

  •   determination of the recovery rates (see: figure)
  •   careful selection of the EPOS materials to avoid contaminations and wall adsorptions, respectively
  •   checking of the blank values
  •   comperative studies by conventional, validated procedures of sampling and sample preparation and the EPOS-procedure
  •   calibration via response values of external and internal standards
  •   multiple determinations to check the reproducibility of the analytical procedure
histogram: determination of the recovery rates

Recovery rates of several testing substances in a spiked sea water, subdivided into:
           A - adsorption column: 1. fraction (hexane/acetone mixture)
           B - adsorption column: 2. fraction (dichlormethane)
           C - filter
           D - wall adsorption at the sample vessel
           E - outlet water
testing substances: naphtalene (Naph), fluorene (Fl), phenantrene (Phen), fluoranthene (Flu), benz-a-pyrene (BaP), benzo-g,h,i-perylene (BghiP); 2,2',3,4,4',5' - hexachlorbiphenyle (CB138); a-, b-, g - hexachlorcyclohexane (a-,b-,g-HCH)


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More information on the subject:
MARNET monitoring system


If you have any additional questions, please e-mail Kai Herklotz or phone +49 40 3190 - 3230
Sieglinde Weigelt-Krenz or phone +49 40 3190 - 3310

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 © 2016 Bundesamt für Seeschifffahrt und Hydrographie Last Update: 19-Apr-2013 18:02:27  
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