In situ monitoring of eutrophication

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Revision as of 10:26, 7 November 2013 by Carolienk (talk | contribs) (Temperature)
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Introduction

In situ monitoring is the observation and / or measurement of events in its original place (Latin: situs). Oceanographic instruments containing different types of sensors are used to monitor eutrophication in coastal waters. Sensors detect and respond to electrical or optical signals and convert the physical, chemical or biological parameter into a signal which can be measured electrically.

Oceanographic instruments

CTD

The CTD[1][2] - Conductivity (salinity), Temperature and Depth (pressure) recorder - is the standard oceanographic tool for continuously measurement of physical properties of sea water. The CTD is mostly attached to a frame with water-collecting Niskin bottles (CTD rosette). From the deck the rosette is lowered on a cable down to the seafloor and once in the water data are transferred via a conducting cable connecting the CTD to a computer on a ship. The Niskin bottles are closed at predefined depths to target water samples for further analysis. Other sensors to measure chemical or biological parameters such as dissolved oxygen, chlorophyll fluorescence (phytoplankton concentrations) and water light transmission can be added to the cluster.

Sensors

In this section we focus only on the sensors that measure parameters that need to be monitored in the frame of the OSPAR Eutrophication Monitoring Programme: [3]

Temperature

The simplest mechanical way to measure temperature is by using a mercury-in-glass thermometer. They are commonly used to measure sea surface temperature by placing it in a bucket of sea water. The most commonly used temperature sensors in oceanography are the electrical temperature sensors: the Resistance Temperature Detectors (RTDs) and the thermistors. A thermistor is a type of resistor composed of a small piece of electrically semiconductor material such as a resistor which exhibits a large change in resistance proportional to a small change in temperature (sensitive). Thermistors usually have negative temperature coefficients which means the resistance of the thermistor decreases as the temperature increases. The thermistor relies upon measuring electrical resistance which is directly or indirectly or inversely proportional to temperature. Thermistors are inexpensive, easily-obtainable temperature sensors. They are easy to use and adaptable.

Salinity

  • Phytoplankton chlorophyll-a
  • Phytoplankton indicator species
  • O2-concentration
  • Macrophytes
  • Benthic communities
  • Nutrients

See also

References

  1. http://www.whoi.edu/instruments/viewInstrument.do?id=1003[1]
  2. http://noc.ac.uk/research-at-sea/nmfss/nmep/ctd[2]
  3. OSPAR Commission (2005), Agreement on the Eutrophication Monitoring Programme (Reference Number: 2005-4)[3]


The main author of this article is Knockaert, Carolien
Please note that others may also have edited the contents of this article.

Citation: Knockaert, Carolien (2013): In situ monitoring of eutrophication. Available from http://www.coastalwiki.org/wiki/In_situ_monitoring_of_eutrophication [accessed on 31-10-2024]