Campbell Scientific OBS-5+ Sediment Concentration Monitor and Pressure Sensor - Manual (Page 45)

OBS-5+ System
FIGURE 10-3. Effects of disaggregation methods
Finally, flocculation of clay particles in estuaries can affect sensitivity by
causing small particles to clump together into larger ones to which the OBS-5+
is less sensitive. For example, when a dredge works into a zone of saline water
where flocculation occurs, an OBS-5+ can indicate less than the actual level of
SSC.
A summary of interference effects on OBS-5+ measurements follows.
1) Any action that makes sediment particles smaller, such as disaggregation,
or larger, aggregation, during the calibration process than they will be in
the environment will cause SSC to appear to increase or decrease when
there has been no actual change.
2) Processes in the environment that make sediment particles larger than they
were during a calibration will produce an apparent decline in SSC.
Conversely, an environmental process that makes particles smaller, such as
deflocculation or disaggregation, will cause SSC to appear to increase.
3) When particles become more or less reflective than they were during
calibration, or their shape changes, SSC will appear to decrease or increase
independent of an actual SSC change.
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