Campbell Scientific OBS-5+ Sediment Concentration Monitor and Pressure Sensor - Manual (Page 44)

OBS-5+ System
FIGURE 10-2. Near-infrared reflectivity of minerals
Reactive Sensitivity
10.3 Particle Shape, Flocculation, and Disaggregation
Particle shape can be an interfering factor. The sensitivity of an OBS-5+
sensor to plate-shaped particles is about ten times higher than it is to spherical
particles. Disaggregation of dry sediment by grinding can cause the sediment
to become finer grained than it was in the environment and this will bias a
sediment calibration. A good example of how much OBS-5+ readings can
change as a result of the disaggregation is shown in FIGURE 10-3. The slope
of each line on the graph indicates the sensitivity of an OBS sensor when
calibrated with sediment disaggregated in a particular way. The more
mechanically aggressive a disaggregation method is, the more sensitive the
sensor will be. Sediments susceptible to disaggregation effects include: 1)
organic-rich estuarine mud, 2) cohesive and flocculated suspended matter, and
3) clay-rich sediment.
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