Data from Lab Experiments to Support Interim Guidance for Performing Calibration Checks on the Sequoia Scientific LISST-ABS Acoustic Backscatter Sensor

As part of its mission to unify and standardize research and development activities of Federal agencies involved in fluvial sediment studies, the Federal Interagency Sedimentation Project (FISP) partnered with the USGS Wyoming-Montana (WY-MT) Water Science Center to examine the potential for use of standard, low-tech laboratory equipment to perform calibration checks on the LISST-ABS™ sensor (hereinafter ‘ABS sensor’) on long-term deployments. The ABS sensor was developed by Sequoia Scientific (Sequoia) as an alternative to turbidity sensors for monitoring suspended sediment concentrations (SSCs) in surface waters. The lab experiments were intended to provide USGS scientists and the public with interim guidance to assist in operation and maintenance of the ABS sensor.

The apparatus components chosen for the lab experiments consisted of a benchtop stir plate, 2-liter (L) glass beaker, stir bar, and benchtop stand. Three Sequoia ABS sensors were used in each step of the lab experiments, and a fourth was used for the field deployment. The data contained in this data release represent raw readings recorded from the ABS sensors over a range of sediment concentrations in units of milligrams per liter (mg/L). The readings were obtained via a software interface between a notebook computer attached via to the ABS sensors by communication The software interface was developed by Sequoia and sold alongside the sensors. The first five lines of each data file represent a header that contains additional, non-quantitative information including the serial number of the sensor being used to take readings.

The data contained in this data release were taken during tests of accuracy and repeatability for different combinations of stir bar and sediment standards. The term ‘sediment standards’ refers to sediments in which the nominal diameters of the particles in a mixture are known with reasonable precision. For the accuracy tests, concentration test intervals for sediment standards were chosen to represent a standard range of concentrations 1.1, 3.2, 10.4, 100, 1,000, and 10,000 mg/L. For the repeatability tests, concentration test intervals for particle standards were chosen to replicate Sequoia Scientific’s calibration intervals: 1.1, 10.4, 100, 1,000, and 10,000 mg/L. The data are organized by sediment standard, sensor serial number, concentration, and stir bar type. The data contained in this data release were used to compute standard statistics and errors and create figures 5 through 8, and tables 4 through 10 in the accompanying Open-File Report (OFR) which describes the results of the laboratory experiments.