In the realm of water quality monitoring, turbidity sensors provide one of the most widely used optical measurements. Scientists, resource managers, and other aquatic specialists use turbidity measurements to provide an estimate of water clarity, for indications of sediment transport, and for many other studies requiring an estimate of particulate loading in the water. Turbidity sensors provide in-water particulate concentrations most commonly derived from optical backscattering measurements. They are calibrated relative to a secondary standard such as formazin. Units of measurement are expressed in Nephelometric Turbidity Units (NTUs) or Formazin Turbidity Units (FTUs) and pertain to a specific concentration of the given standard medium.

While turbidity measurements are useful as general indicators of suspended particulate concentrations, the measurements cannot be used as absolute indicators. Since different materials and different material sizes possess different Volume Scattering Functions the amount of light scattered into a given angle captured by the sensor receiver varies. This results in errors in measured concentrations.

Sensors
ECO FLNTU, BB:
The FLNTU measures fluorescence and turbidity simultaneously.
Our BB scattering sensors can also be calibrated for NTU output.

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Intro to IOPs
More on IOPs: absorption • beam attenuation • volume scattering function • fluorescence • turbidity • scattering