Light scattering by pure water and seawater: the depolarization ratio and its variation with salinity

We measured the linearly polarized light scattering of pure water and seawater at various salinities and estimated the depolarization ratio using five different methods of data analysis after removing the scattering due to contamination by residual nanoparticles. The depolarization ratio values (δ) estimated for pure water using these different methods are largely consistent with each other and result in a mean value of 0.039±0.001. For seawater, our results reveal a trend of a slight linear increase of δ with salinity (S), δ=0.039+a₁×S, where a₁ varies in the range of 1×10^-4 to 2×10^-4 between the methods.