Continental runoff of solid matter as a source of dissolved calcium in the ocean

Abstract

It was found in the experiments that the transfer of calcium from the solid phase to the dissolved state took place under the interaction of terrigenous matter (bottom sediments from the freshwater lake) with the solutions modeling the interstitial waters of the sediments of high-productive regions of the ocean. This calcium might later bind the autochthonous CO₂ formed in the ocean under the oxidation of organic matter. According to the data of the three-week experiment, 1 g of the terrigenous matter evolved on average ∼2.3 mg Ca²⁺ into interstitial solutions, which conforms to the involving of exclusively surface layers of the grains of the solid phase into the reaction. In view of the true rate of halmyrolysis of the grains of terrigenous silicates (a few μm/year), at the value of the continental runoff of solid matter being equal to 16 billion t/year, the amount of dissolved calcium supplied to the ocean as a result of the transformation of the terrigenous sedimentary matter at the stage of diagenesis amounts to 250–440 million t/year and over. These values are 3- to 5-fold higher that the amount of calcium in the continental runoff of dissolved matter supplied by the erosion of silicates and capable of forming carbonate sediments in the ocean under the interaction with autochthonous CO₂, unlike the calcium that is product of the dissolution of carbonate rocks.