http://researchonline.federation.edu.au/vital/access/manager/Index ${session.getAttribute("locale")} 5 http://researchonline.federation.edu.au/vital/access/manager/Repository/vital:10387 Wed 07 Apr 2021 13:55:44 AEST ]]> http://researchonline.federation.edu.au/vital/access/manager/Repository/vital:10374 Wed 07 Apr 2021 13:55:44 AEST ]]> http://researchonline.federation.edu.au/vital/access/manager/Repository/vital:10376 5, the rates of Fe(II)-catalyzed schwertmannite transformation were several orders of magnitude faster than transformation in the absence of Fe(II). Complete transformation of schwertmannite occurred within only 3-5 h at pH > 6 and Fe(II)(aq) ≥ 5 mmol L-1. Model calculations indicate that the Fe(II)-catalyzed transformation of schwertmannite to goethite greatly decreases the reactivity of the Fe(III) pool, thereby favoring SO4-reduction and facilitating the formation of iron-sulfide minerals (particularly mackinawite, tetragonal FeS). Examination of in situ sediment geochemistry in an acid-sulfate system revealed that the rapid Fe(II)-catalyzed transformation was consistent with an abrupt shift from an acidic Fe(III)-reducing regime with abundant schwertmannite near the sediment surface, to a near-neutral mackinawite-forming regime where goethite was dominant. This study demonstrates that the Fe(II) pathway exerts a major influence on schwertmannite transformation and iron-sulfide formation in anoxic acid-sulfate systems. These findings have important implications for understanding acidity dynamics and trace element mobility in such systems. © 2008 Elsevier Ltd. All rights reserved.]]> Wed 07 Apr 2021 13:55:44 AEST ]]> http://researchonline.federation.edu.au/vital/access/manager/Repository/vital:17423 Tue 14 Mar 2023 16:59:17 AEDT ]]>