EarthRef.org Reference Database (ERR) -- Spivack & Staudigel 1994

While the input of river-alkalinity into seawater is relatively well known, the complementary acidity production is poorly understood. Using the major-element budget of seafloor alteration of the upper 500 m of 120-Ma-old oceanic crust at DSDP/ODP Sites 417A, 417D and 418A in the central western Atlantic, we estimate the acidity flux associated with the low-temperature weathering of the upper oceanic crust. The acidity flux is calculated based on major-element fluxes and charge-balance considerations. The relevant chemical fluxes from seawater to the upper crust are 4.1 +/- 0.1; 1.4 +/- 1.4; 2.2 +/- 0.6 and -12 +/- 2 10(11) mol yr-1 for K, Mg, Na and silicate-Ca, respectively. The associated acidity flux is (3.5 +/- 3) . 10(11) eq yr-1. Relative to continental weathering, these fluxes are significant for K and silicate-Ca, but are minor for Na, Mg and acidity. Thus, riverine fluxes of alkalinity are not significantly balanced by acidity fluxes from low-temperature upper ocean crust alteration.

Journal
Chemical Geology
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Elsevier Science
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