Provide one example each for an element that is (1) added to the ocean and (2) removed from the ocean through hydrothermal circulation (=through oceanic crust ≠ plume chemistry). Provide the chemical mechanisms of the addition and removal processes.
(2) Mg + SO4 removal: Mg2+ + Basalt→Mg-Basalt + Ca2+ + H+, removal of Magnesium associated with proton and Ca2+ release→calcium is partially stripped out again due to precipitation with SO42- at high temperatures
(1) Input of sulphides due to reduction of seawater sulphate: SO42- → H2S; also input of Mn, Fe, Cu, Zn, Si
Which of the following chemical constituents are typically found in high concentrations in high-
temperature hydrothermal vent waters, and provide the mechanism for the high concentrations:
(1) H2S (2) Fe3+ (3) H4SiO4 (4) CH4 (5) Mg2+
H2S, H4SiO4 and CH4 are typically found in hydrothermal vent fluids H2S: SO42- →H2S H4SiO4: ? CH4: CO2 + 4 H2 →CH4 + 2 H2O
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