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Section 8. Factors Affecting OBS Response

0510

Sediment Concentration (g/l)

Signal (V)

FIGURE 8.3-1. Response at High Sediment Concentrations

8.4 Sediment Color

Sediment color, after particle size, has a major effect on OBS sensitivity, and if

it changes, it can degrade the accuracy of measurements. Although OBS

sensors are “color blind”, “whiteness”, color, and IR reflectivity (measured by

an OBS sensor) are well correlated. Calcite, which is highly reflective and

white in color, will produce a much stronger OBS signal on a mass-

concentration basis than magnetite, which is black and IR absorbing.

Sensitivity to colored silt particles varies from a low of about one for dark

sediment to a high of about ten for light gray sediment; see FIGURE 8.4-1. In

areas where sediment color is changing with time, a single calibration curve

may not work. Resulting errors will depend on the relative concentrations of

colored sediments.

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Campbell OBS-3A Especificações Página 49