Existing instruments and measurement systems are generally used for measuring water quality.
For studying new variables, however, such systems do not exist or the existing systems are often extremely ill-equipped in terms of the quality or accuracy required.
In such cases, the Department of In Situ Measurement Systems creates new, or adapts existing, systems and continually develops them further.
This development takes place predominantly in conjunction with companies from the industrial sector.
The development of the automated “FerryBox” measurement system is one such example:
FerryBoxes are used on ships traveling regularly scheduled routes. -image: HZG-
The FerryBox, developed by the Department of In Situ Measurements is an automated measurement system for determining physical and chemical measurement variables in the upper-most water layer.
The system is installed on ships traveling certain regularly scheduled routes (e.g., on ferries or cargo ships). The FerryBox instruments measure all variables that are to be recorded approximately every twenty seconds. This means that a new measurement is received approximately every one hundred metres along the shipping route. These regular water quality measurements taken on a fixed route enable detailed observations over a long period of time and in a specific region of substantial size. Using this data, scientists can obtain a meaningful image of the marine processes occurring there.
Schematic representation of a FerryBox. -image: HZG-
A FerryBox is an instrument cabinet approximately the size of a refrigerator that is usually installed in the engine room of a ship, as close as possible to an already existing water intake.
A water circulation system with various instruments is located inside this cabinet. The seawater is sucked in from the outside into the water circulation system. The different variables are thereby measured by various instruments. The data obtained, such as water temperature, salinity and oxygen content, or the concentration of suspended matter, is transferred to the mainland via satellite or mobile network.
The system is automatically halted when the ship reaches the harbour so that no contaminated harbour water enters. The system is re-started as soon as the ship leaves the harbour again. While the ship is in port, the system automatically "cleans" itself, whereby the entire unit is flushed with slightly acidic fresh water to prevent biological growth (e.g., algae) on the sensors.
In addition to the measurements, water samples can be obtained using an automated sampler during the journey.
In addition to operating FerryBoxes on fixed routes, such boxes are also installed on research ships such as the Polarstern as well as on the cruise ship "Mein Schiff 3".
Measurement instruments for use in an automated system like the FerryBox must be robust, sufficiently precise and require little maintenance.
Scientists calibrating a sensor in the laboratory. -image: HZG-
The sensors available on the commercial market often do not adequately fulfil these criteria.
The Department of In Situ Measurements therefore improves existing sensors and adapts them to the requirements for real operating conditions.
If such adaptation is impossible, the scientists develop their own sensors and analysis devices together with partners from the industrial sector.