Simultaneous determination of in situ vertical transitions of color, pore-water metals, and visualization of infaunal activity in marine sediments
Simultaneous determination of in situ vertical transitions of color, pore-water metals, and visualization of infaunal activity in marine sediments
The vertical color transition from brown to gray-green in marine sediments is linked to the Fe redox boundary and is commonly used as a proxy for biogeochemical state. We combine time-lapse sediment profile imaging with diffusive gradient thin (DGT) gels to obtain simultaneous in situ measurements of sediment color profiles, pore-water Fe and Mn profiles, and qualitative estimates of faunal activity at the Oyster Ground and North Dogger (North Sea). Analysis of Fe and Mn profiles using generalized additive modeling reveals that high variability between profiles within the sites makes it difficult to determine any intersite differences in trace metal behavior. At the Oyster Ground, the depth of sediment color transition (4.78 +/- 0.76 cm) was not significantly different from the Fe redox boundary (7.67 +/- 4.04 cm). At the North Dogger, there was a significant discrepancy between the depth of the sediment color transition (2.86 +/- 0.78 cm) and the Fe redox boundary (10.17 +/- 1.04 cm), which most likely results from high sulfate reduction rates at the North Dogger, leading to complexation of reduced iron to a form not available to the DGT technique. The differences in the coupling of sediment color and the Fe redox boundary between stations is likely to be related to variations in recent infaunal bioturbation activity, rather than variations in sediment source or fundamental differences in bulk sediment chemistry. Our results highlight the importance of the infaunal community in mediating Fe and Mn cycles, which are key pathways in the degradation of organic matter, and suggest that descriptions of bulk chemistry alone may be insufficient to understand the dynamics of biogeochemical cycling.
1801-1810
Teal, Lorna R.
89ee9eba-9405-4a1a-aa30-e3e3181980cf
Parker, Ruth
ce41b78b-a29a-4b17-a517-3b2e79f17bba
Fones, Gary
93d3b834-9ef2-4d69-a277-8f8a734ddbc2
Solan, Martin
c28b294a-1db6-4677-8eab-bd8d6221fecf
September 2009
Teal, Lorna R.
89ee9eba-9405-4a1a-aa30-e3e3181980cf
Parker, Ruth
ce41b78b-a29a-4b17-a517-3b2e79f17bba
Fones, Gary
93d3b834-9ef2-4d69-a277-8f8a734ddbc2
Solan, Martin
c28b294a-1db6-4677-8eab-bd8d6221fecf
Teal, Lorna R., Parker, Ruth, Fones, Gary and Solan, Martin
(2009)
Simultaneous determination of in situ vertical transitions of color, pore-water metals, and visualization of infaunal activity in marine sediments.
Limnology and Oceanography, 54 (5), .
(doi:10.4319/lo.2009.54.5.1801).
Abstract
The vertical color transition from brown to gray-green in marine sediments is linked to the Fe redox boundary and is commonly used as a proxy for biogeochemical state. We combine time-lapse sediment profile imaging with diffusive gradient thin (DGT) gels to obtain simultaneous in situ measurements of sediment color profiles, pore-water Fe and Mn profiles, and qualitative estimates of faunal activity at the Oyster Ground and North Dogger (North Sea). Analysis of Fe and Mn profiles using generalized additive modeling reveals that high variability between profiles within the sites makes it difficult to determine any intersite differences in trace metal behavior. At the Oyster Ground, the depth of sediment color transition (4.78 +/- 0.76 cm) was not significantly different from the Fe redox boundary (7.67 +/- 4.04 cm). At the North Dogger, there was a significant discrepancy between the depth of the sediment color transition (2.86 +/- 0.78 cm) and the Fe redox boundary (10.17 +/- 1.04 cm), which most likely results from high sulfate reduction rates at the North Dogger, leading to complexation of reduced iron to a form not available to the DGT technique. The differences in the coupling of sediment color and the Fe redox boundary between stations is likely to be related to variations in recent infaunal bioturbation activity, rather than variations in sediment source or fundamental differences in bulk sediment chemistry. Our results highlight the importance of the infaunal community in mediating Fe and Mn cycles, which are key pathways in the degradation of organic matter, and suggest that descriptions of bulk chemistry alone may be insufficient to understand the dynamics of biogeochemical cycling.
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Published date: September 2009
Organisations:
Ocean Biochemistry & Ecosystems
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Local EPrints ID: 339688
URI: http://eprints.soton.ac.uk/id/eprint/339688
ISSN: 0024-3590
PURE UUID: 7ddf4937-3bf1-4c6f-8244-0bbc9be86657
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Date deposited: 28 May 2012 16:09
Last modified: 15 Mar 2024 03:32
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Author:
Lorna R. Teal
Author:
Ruth Parker
Author:
Gary Fones
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