Calibration of the transparency tube for estimating turbidity in estuarine systems

Turbidity, quantified in turbidity units (nephelometric or formazin), is a common and valid measure of water quality related to transparency. A transparency tube (TT) is an economical tool developed to estimate water clarity as an alternative to the Secchi disk, but it is also frequently used to estimate turbidity. Although the relationship between TT measures and turbidity is well characterized for freshwater river and lake systems, this relationship has not been tested for estuarine waters. The objective of the current study was to empirically determine the TT-turbidity relationship for estuarine waters and compare these results with the traditional freshwater system conversions. We obtained 107 measurements of TT depth, turbidity, total suspended solids, CDOM absorbance, Secchi depth, and chlorophyll a at 22 estuarine locations in South Carolina over a one-year period. Linear regressions provide conversion equations that can be applied to estuarine waters. The TT-turbidity relat..., A total of 22 estuarine locations were sampled 107 times in 2022 - 23, stretching from North Myrtle Beach to Port Royal Sound along the coast of South Carolina (Fig. 2). The goal was to include a range of water types with different turbidity characteristics from tidal regions of coastal waterbodies. Site selection was determined based on accessibility, usually from a boat dock or launch ramp.
Water transparency, photosynthetically available radiation (PAR) depth profiles, salinity, and temperature were obtained on-site. Transparency was measured using a 120 cm “transparency tube” (Eisco Labs, Victor, NY, PN PH1120148120SPR). The transparency tube (TT) was filled with well-mixed water from the sample site using a 1 m bailer and carboy. While looking through the top opening of the tube, water was slowly drained out of the bottom until the Secchi disk at the bottom of the tube was visible, and the depth of the remaining water (in cm) was recorded. The water column length in the TT was reco..., # Calibration of the transparency tube for estimating turbidity in estuarine systems

Dataset DOI: [10.5061/dryad.rxwdbrvn9](10.5061/dryad.rxwdbrvn9)

## Description of the data and file structure

The primary objective of our study was to empirically determine the transparency tube (TT) to turbidity (ntu) relationship for estuarine and coastal waters and compare these results with traditional freshwater system conversions. Our aim was to evaluate the accuracy of the freshwater system conversions for estuarine systems. A second objective was to examine the correlations between TT, Secchi depth, total suspended solids, chromophoric dissolved organic matter (CDOM), and the diffuse attenuation coefficient (kd) for photosynthetically available radiation (PAR).

Estuarine locations (22 sites) were sampled for a total of 107 times in 2022 - 23, stretching from North Myrtle Beach to Port Royal Sound along the coast of South Carolina. The goal was to include a range of water types with differen...,