Fertilizing potential of volcanic ash in ocean surface water

The fertilization potential of newly erupted and well-preserved ash from th e 2000 Hekla eruption in Iceland was measured for the first time by flow-th rough experiments. As previously shown, (1) the North Atlantic Ocean, inclu ding the subarctic seas surrounding Iceland, is the largest net sink of the world's oceans for atmospheric CO2, owing to biological drawdown during su mmer; (2) almost complete consumption of phosphate in chlorophyll-rich area s of the North Atlantic Ocean might limit primary production; and (3) in th e southern Pacific Ocean and parts of the equatorial Pacific Ocean iron mig ht limit primary production, We found through laboratory experiments that v olcanic ash exposed to seawater initially releases large amounts of adsorbe d phosphate, 1.7 mu mol(.)g(-1.)h(-1); iron, 37.0 mu mol(.)g(-1.)h(-1); sil ica, 49.5 mu mol(.)g(-1.)h(-1); and manganese, 1.7 mu mol(.)g(-1.)h(-1). Di ssolution of acid aerosols adsorbed to the surface of the ash caused the hi gh initial release of major and trace elements. Because of the instantaneou s dissolution of adsorbed components when newly erupted volcanic ash comes in contact with the ocean surface water, macronutrients and "bioactive" tra ce metals are released fast enough to become available to support primary p roduction.