Kinetic and Thermodynamic Properties of the Biogenic Silica-Sea Water System: From Laboratory-Based Experiments to the Oceanic Silica Cycle

Abstract

There have been numerous studies of the production, dissolution and preservation of biogenic silica in the oceans. Nonetheless, a complete mechanistic and quantitative understanding of the dissolution process is still lacking. This interferes with our ability to systematically predict silica dissolution fluxes under variable conditions and, hence, it represents a major obstacle to the use of the accumulation rate of biogenic silica as a palaeoproductivity index, and to the reconstruction of the silica cycle through geological time. Using stirred flow-through reactors, we have measured the effects of a number of critical physical and geochemical parameters on the solubility and dissolution kinetics of biogenic silica in sediments from the Southern Ocean. In this paper, we analyse whether the data set obtained can explain the reactivity and solubility of biogenic silica in a range of marine environments.