Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

Sulfur and Iron Cycling in a Coastal Sediment: Radiotracer Studies and Seasonal Dynamics

Lars Moeslund, Bo Thamdrup and Bo Barker Jørgensen
Biogeochemistry
Vol. 27, No. 2 (1994), pp. 129-152
Published by: Springer
Stable URL: http://www.jstor.org/stable/1469040
Page Count: 24
  • Download ($43.95)
  • Cite this Item
Sulfur and Iron Cycling in a Coastal Sediment: Radiotracer Studies and Seasonal Dynamics
Preview not available

Abstract

The seasonal variation in sulfate reduction and the dynamics of sulfur and iron geochemistry were studied throughout a year in sediment of Aarhus Bay, Denmark. A radiotracer method for measuring sulfate reduction rates was applied with incubation times down to 15 min and a depth resolution down to 2 mm in the oxidized surface layer of the sediment. The radiotracer data were analyzed by a mathematical model which showed that, due to partial, rapid reoxidation of radioactive sulfide during incubation, the actual reduction rates in this layer were probably underestimated 5-fold. In the deeper, sulfidic zone, measured rates appeared to be correct. Sulfate reduction followed the seasonal variation in temperature with maximum activity at 1-2 cm depth in late summer. In spite of its rapid production, free H2S was detectable in the porewater only below the depth of free Fe2+ at 6-7 cm throughout the year. Following the massive sedimentation from a spring phytoplankton bloom, anaerobic degradation of phytoplankton detritus was strongly stimulated over several weeks. A transient reversed redox zonation developed with a thin, black zone on top of the brown, oxidized sediment layer due to intensive sulfate and iron reduction. Mineralization through sulfate reduction was equivalent to two thirds of the annual net sedimentation of organic matter.

Page Thumbnails

  • Thumbnail: Page 
[129]
    [129]
  • Thumbnail: Page 
130
    130
  • Thumbnail: Page 
131
    131
  • Thumbnail: Page 
132
    132
  • Thumbnail: Page 
133
    133
  • Thumbnail: Page 
134
    134
  • Thumbnail: Page 
135
    135
  • Thumbnail: Page 
136
    136
  • Thumbnail: Page 
137
    137
  • Thumbnail: Page 
138
    138
  • Thumbnail: Page 
139
    139
  • Thumbnail: Page 
140
    140
  • Thumbnail: Page 
141
    141
  • Thumbnail: Page 
142
    142
  • Thumbnail: Page 
143
    143
  • Thumbnail: Page 
144
    144
  • Thumbnail: Page 
145
    145
  • Thumbnail: Page 
146
    146
  • Thumbnail: Page 
147
    147
  • Thumbnail: Page 
148
    148
  • Thumbnail: Page 
149
    149
  • Thumbnail: Page 
150
    150
  • Thumbnail: Page 
151
    151
  • Thumbnail: Page 
152
    152