A sequential extraction procedure for particulate manganese and its application to coastal marine sediments

An existing sequential extraction scheme for particulate iron (Fe) is evaluated manganese (Mn) using a range of Mn standards. The consists 5 steps and quantifies operationally defined pools (1) poorly ordered oxides phosphates (ascorbic acid extractable); (2) carbonates sulfides (1 M HCl extractable), (3 4) crystalline (citrate buffered dithionite ammonium oxalate extractable, respectively) (5) associated with pyrite (concentrated HNO3 extractable). Application the to coastal sediments from six locations (Black Sea, Baltic Bothnian Gulf Mexico Chesapeake Bay) highlights dependency sediment partitioning on bottom water redox conditions. In deposited in anoxic sulfidic (euxinic) waters, mostly present carbonates, non-reactive forms, approximately equal amounts. We find that periodically euxinic hypoxic (oxygen <63 ?mol L?1) dominate over two other fractions, small amounts are observed. oxygenated oxides, Mn-rich vivianite-type minerals no pyrite-bound A large advantage it forms Fe simultaneously. Given role as proxy, separation specific relevance.