The sediment would appear yellow/orange if it were chromium (VI) instead of green or blue/violet. If you are really good, you can determine the nickel (II) oxide : chromium (III) oxide ratio from the stainless steel by the shade of green.
R. Steven Pappas, Ph.D.
Smoke Analysis Group
Centers for Disease Control & Prevention
4770 Buford Hwy, M.S. F-44
Atlanta, GA USA 30341-3717
[log in to unmask]
From: PLASMACHEM-L: Analytical Chem.(ICP's, DCP's, MIP's). [mailto:[log in to unmask]] On Behalf Of Johnson, Thomas Martin
Sent: Friday, September 16, 2011 2:43 PM
To: [log in to unmask]
Subject: Re: Cr in marine sediment
Chromium goes to Cr(VI) only in highly oxidized, and usually alkaline, environments. If those sediment are anoxic, then almost certainly the Cr is all Cr(III).
Thomas M. Johnson
University of Illinois at Urbana-Champaign
Associate Professor and Department Head
Department of Geology, MC-102
208 Natural History Building
1301 West Green Street
Urbana, IL 61801
Phone (217) 244-2002
On Sep 16, 2011, at 1:27 PM, Thomas J. Manning wrote:
Anyone care to guess the oxidation state of chromium in marine sediment - next to an old stainless steel wall. Green Color suggests CrO3 (neutral = +6 charge) but we have no experience with this species in this environment. Thanks - have a good weekend! Tm