Manganese, iron and sulfur cycling in a coastal marine sediment, Aarhus bay, Denmark

Details Manganese, iron and sulfur cycling in a coastal marine sediment, Aarhus bay, Denmark Manganese, iron and sulfur cycling in a coastal marine sediment, Aarhus bay, Denmark

Dec 1994

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1994gecoa..58.5115t&link_type=abstract

Geochimica et Cosmochimica Acta, vol. 58, Issue 23, pp.5115-5129

Computer Science

31

Scientific paper

The seasonal variation in oxidized and reduced pools of Mn, Fe and S, as well as the rates of SO 4 2- reduction, were studied in a fine-grained sediment. Below the 1-5 mm thick oxic zone, a zone of net Mn reduction extended to 1-2 cm depth, while iron reduction was found to 4-6 cm depth. Although the reactive Mn oxide pool was ten times smaller than the reactive Fe(III) pool, the average ratio between depth gradients of Fe and Mn oxides was only 1.7, which implied that rates of Mn and Fe reduction were similar. Sulfate reduction was maximal near the bottom of the suboxic zone, but fine-scale measurements showed that it extended to the upper 0-2.5 mm during summer, when the zones of Mn and Fe reduction were compressed towards the surface. Most of the H 2 S produced precipitated as iron sulfides and S 0 by reaction with Fe. Both Fe(III) and a nonsulfur-bound authigenic Fe(II) pool reacted efficiently with H 2 S. The authigenic Fe(II) pool was present at one hundredfold higher concentration than dissolved Fe 2+ . Only 15% of the precipitated sulfide was buried permanently. Most of the reoxidation of reduced S occurred within 1 cm of the sediment-water interface and was supported by upward bioturbation. All of the estimated Mn reduction could be coupled to the reoxidation of reduced S and Fe. Partial oxidation of H 2 S, forming S 0 and pyrite, accounted for 63% of the estimated Fe reduction. The remaining Fe reduction was coupled to complete oxidation of reduced S or to C mineralization. The settling of a diatom spring bloom caused distinct maxima in SRR and Mn 2+ at 0.5-1 cm depth within two weeks. In autumn, the reactive Mn oxides were depleted due to a net release of Mn 2+ to the water column. Thus, the Mn cycle extended significantly into the water column, while a constant Fe pool over the year suggests that the Fe cycle was restricted to the sediment.

Affiliated with

Also associated with

No associations

Rating

Manganese, iron and sulfur cycling in a coastal marine sediment, Aarhus bay, Denmark does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Manganese, iron and sulfur cycling in a coastal marine sediment, Aarhus bay, Denmark, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Manganese, iron and sulfur cycling in a coastal marine sediment, Aarhus bay, Denmark will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1408209