The monography is devoted to the complex study the changeability of hydrophysical fields of the Caspian Sea in a wide range on spatial-temporal scales and studying the influence of these features on spreading of foreign admixtures in the sea. The regularity of turbulent diffusion in the Caspian Sea was determined on the basis of unique experiments carried out in self zone of the sea, the theoretical formulas were worked out for calculation of length, active phase and thickness the spreading of flooded stream of foreign admixtures.