Anthropogenic perturbations of the silicon cycle at the global scale:Key role of the land-ocean transition

摘要

Silicon (Si), in the form of dissolved silicate (DSi), is a key nutrient in marine and continental ecosystems. DSi is taken up by organisms to produce structural elements (e.g.,shells and phytoliths) composed of amorphous biogenic silica (bSiO_2). A global mass balance model of the biologically active part of the modem Si cycle is derived on the basis of a systematic review of existing data regarding terrestrial and oceanic production fluxes, reservoir sizes, and residence times for DSi and bSiO_2. The model demonstrates the high sensitivity of biogeochemical Si cycling in the coastal zone to anthropogenic pressures, such as river damming and global temperature rise. As a result, further significant changes in the production and recycling of bSiO_2 in the coastal zone are to be expected over the course of this century.