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#11
12-20-2003, 03:50 AM
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Bob, The 2004 issue of Marine fish and Reef magazine has an excellent article on sand beds by Richard Harker. There are about 23 references. The basic point of the article is that with our overly simplistic understanding of sand bed denitrification processes we've made the mistake of thinking we need DSBs but we can have anoxic and suboxic microzones with in the top layer of sand. "Large areas of the sediment surface are suboxic, especiall at night, and that anoxia predominates at depths greather than about 1cm."(King 1990) "Denitrification is most likely to occur close to where nitrification takes place, and this occurs at the surface of the sand. "As much as 70 to 90 percent of the overall denitrification was located at the 1-3 cm depth"(Andersen, 1984). It turns out that an anaerobic habitat can be as small as 1mm, that aerobic and anaerobic habitat essentially coexist, and that as little as 0.08mm distance is sufficient for nitrification and denitrification to take place simultaneously (Fenchel, 1995).
The article goes on, it's rather interesting. Doug 
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