| Comments |
P.377 left column bottom paragraph: "To resolve the various inputs of dissolved Si to the oceans, it is useful to examine germanium, an element located directly under Si in the periodic table. Sea floor hot spring effluents carry a Ge/Si molar ratio of about (11±3)x10^-6, which is much higher than that for rivers (0.54±0.14)×10^-6 and for biogenic silica deposits (0.66±0.12)×10^-6 (primary source). Assuming that biogenic silica from diatoms is the only major sink for Ge in the ocean, Mortlock et al. (primary source) constructed a mass balance for riverine and hydrothermal inputs of Ge and Si into the ocean versus biogenic deposits. Given [investigators’] estimate for riverine Si inputs, this leads to FH (hydrothermal activity) = 0.15±0.11 Tmol Si/year, which is less than 10% of that predicted from the global 3He model and from the Sr isotope balances." 1Tmol=1 teramole = 10^12 moles |