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High Resolution O2 Measurements with OXY Flux

Eddy Covariance Oxygen Microsensor ECO-PSt7

The optical oxygen microsensors for eddy covariance enable measurements with 10 Hz sampling rate. The ECO-PSt7 have a tip size of 30 µm, so there is only minimal flow disturbance. They deliver precise on-the-spot measurements. The sensor fiber is integrated in a robust steel cannula leaving only 3 mm of the sensitive sensor tip exposed. This way the sensor can safely be handled and the risk of accidental sensor damage is reduced to a minimum - ensuring reliable data collection. ECO-PSt7 together with the OXY Flux oxygen meter are an inexpensive solution to extend your eddy covariance measurement set-up.

  • Fast response time, 10 Hz sampling frequency
  • Robust optical sensor construction
  • Flow insensitive due to optical measurement principle
  • 30 µm tip size - minimal flow field disturbance
  • Linear calibration
  • Easy and inexpensive sensor exchange

Applications

Aquatic Eddy Covariance Measurements over a Dense Seagrass Bed

The graph on the left shows aquatic eddy covariance data measured over a 49 h period with the OXY Flux amplifier over a dense seagrass bed. Graph (A) shows the three velocity components and mean current velocity. Variations in the horizontal x- and y-velocities represent changing tidal currents. The oxygen concentrations measured with fast-responding optical fiber connected to the OXY Flux amplifier and an independent oxygen sensor are shown in (B). The fast-responding optical system produced a 'clean' signal with no spikes or abnormalities despite turbid field conditions. In (C) the cumulative oxygen flux over the 49 h period is depicted. (D) shows the hourly oxygen flux (error bars represent SE, n= 4). Positive flux values represent a release. Light (PAR) measured above the seagrass canopy and water depth with a clear tidal signal are plotted in (E). The daytime oxygen flux (D) had a strong correlation to light (E), whereas the nighttime flux was affected by current flow and wave action.

Data measured and provided by Amelie Berger and Peter Berg (Aquatic Eddy Covariance Research Lab, University of Virginia)


Technical

SpecificationsGaseous & Dissolved O2
Dissolved O2
*after two-point calibration as described in the manual
Measurement range0 - 100 % O2
0 - 100 hPa
0 - 45 mg/L
0 - 1400 µmol/L
Limit of detection0.03 % O215 ppb
Resolution± 0.01 % O2 at 1 % O2
± 0.05 % O2 at 20.9 % O2
± 0.005 mg/L at 0.4 mg/L
± 0.025 mg/L at 9.06 mg/L
Accuracy at + 20 °C* ± 0.05 % O2 or 3 % rel.
Response time (t90)< 0.5 sec.
Properties
Cleaning procedure3 % H2O2, ethanol, soap solution
CalibrationTwo-point calibration in oxygen-free (nitrogen, sodium sulfite solution) and air-saturated environment
Length of optical fiber75 cm
Storage stability5 years provided the sensor material is stored at room temperature in dry conditions and in the dark

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