EFFECTS OF SODIUM, POTASSIUM AND CALCIUM CHLORIDE SALTS ON UNDERWATER VISIBLE LIGHT COMMUNICATION PERFORMANCE AND THEIR PRESENCE IN SOME WATER BODIES OF SOUTHWEST NIGERIA

Abstract

The Salinity is one of the attributes of water that affects underwater wireless optical communication (UWOC) and requires continual investigation. This study investigates the effect of sodium, potassium and calcium chloride salts on transmission of visible light in water via spectroscopy for underwater communication, as well as the presence of these salts in seven water bodies of Southwest Nigeria. Single-salt solutions of each type with varying concentrations were prepared, and their physiochemical properties were measured, as well as their visible light absorbance spectra, from which performance of UWOC for each salt solution at three wavelengths was investigated by simulation using OptiSystem. Water samples were taken from three rivers, two lagoons, and the Atlantic Ocean in Southwest Nigeria and the concentration of the three cations and chloride ion in them were measured as well as their absorbance spectra. For the single-salt solutions, higher absorbance at shorter wavelengths was observed with an increase in salt concentration for sodium and potassium chloride solutions, but calcium chloride solution shows higher absorbance towards longer wavelengths. UWOC simulation results showed that the achievable maximum link distance reduces with salt concentration, varies with wavelength, and is least in calcium chloride solution. For the water bodies, the rivers have low values of salinity and absorbance, while high values were obtained for the lagoons and the Atlantic Ocean. Moreover, their average absorbance showed strong correlations with concentration of calcium and chloride ions than with sodium and potassium ions.