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UP: Fachverband Umweltphysik

UP 7: Aquatic Systems: Limnology, Natural Waters, Wetlands and Soilmoisture

UP 7.2: Vortrag

Mittwoch, 11. März 2026, 11:30–11:45, MER/0002

Sound Speed Contributions of Solutes in Water — •Ivan Selyakov, Lutz Hrdlicka, and Bertram Boehrer — Helmholtz Centre for Environmental Research, Magdeburg, Germany

This study provides a structured investigation of the fundamental property of sound speed in limnic waters, presenting systematic experimental data on the contributions of various electrolytes over a temperature range from 1 ^∘C to 30 ^∘C and concentrations up to 0.05 mol L-1. While established approaches such as the UNESCO formula and the TEOS-10 package describe sound speed in oceanic waters, information on the contributions of specific solutes in freshwater environments remains limited. We observed no evidence of nonlinearities in either temperature or concentration dependences within the studied range and accuracy. Coefficients for calculating sound-speed excess are provided for a range of salts containing all major ions commonly found in natural waters. Contributions in mixtures of salts can be directly added, and a numerical approach is introduced for predicting sound speed in arbitrary mixtures of the investigated ions, including unusual combinations found in volcanic or meromictic conditions. Using our data, isothermal and adiabatic compressibility as well as in-situ density can be calculated with enhanced accuracy. These findings are valuable for applied fields such as acoustic sensing and environmental monitoring, and for advancing theoretical understanding in physical limnology and aquatic thermodynamics. The numerical tool implementing this approach has been validated against the UNESCO formula.

Keywords: Limnic Waters; Sound Speed; Solutes; Natural Waters; Water properties