Hidden erosion on volcanic islands

摘要: Abstract We have studied rivers from 3 volcanic tropical Islands (Guadeloupe and Martinique in Lesser Antilles Reunion) order to evaluate chemical weathering rates. These islands are constituted of very porous pyroclastic deposits, andesitic or basaltic lava flows, allowing significant water infiltration. From hydrological budgets, we estimate that infiltration represents 10% Guadeloupe 40% Martinique. Element fluxes transported by subsurface the ocean been quantified coupling budget with composition sampled waters. This is first rates islands, which takes into account high temperature contribution Subsurface waters impacted high-temperature water–rock interactions present therefore higher concentrations (4 100 times) major trace elements compare surface waters, representing thus respectively 90%, 60% 75% total (surface + subsurface) dissolved flux for Martinique, Reunion. shows importance these fluxes, until now were not estimated basalt geochemical budgets. Chemical 2 5 time than The average calculated 290 t/km2/yr Guadeloupe, 1080 t/km2/yr 270 t/km2/yr values among highest worldwide. Extrapolating this all world-wide, could contribute between 23% 31% global load oceans draining silicate rocks whereas their area represent only 9% rock area.