On the Transformation of the Chemical Composition of Seawater in Interaction with Terrigenous Aerosols

Abstract

Transformation of the chemical composition of seawater upon interaction with loess, an analog of natural terrigenous aerosols of the Pleistocene, was studied experimentally. It was shown that this process leads to a change in the concentrations of major ions (K, Ca, SO4, and HCO3), nutrients (Si and P), and fluorine, while the chloride, sodium, and magnesium contents do not vary due to their high concentrations in seawater. With increasing weight fraction of the solid phase, the sulfate and hydrocarbonate concentrations increase, while the potassium concentration decreases. The calcium and fluorine concentrations either increase or decrease depending on the content of mobile forms of these elements in the samples. The release of silicon and phosphorus into seawater has an asymptotic limit: 2.5–3.3 mg Si/L and 0.012–0.040 mg P/L. The relationship between the change in concentrations of studied components in seawater and the weight fraction of the solid phase corresponds to a hyperbolic function, but with a relatively small weight fraction, it is described by a linear equation, in which the angular coefficient has a positive correlation with the concentration of the component in an aqueous extract from this loess sample. A change in seawater composition upon interaction with loess can be predicted from the composition of their aqueous extracts.