Biogeochemical cycling in an organic-rich coastal marine basin. 6. Temporal and spatial variations in sulfate reduction rates

Journal Article · Fri May 01 04:00:00 EDT 1987 · Geochim. Cosmochim. Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(87)90210-9· OSTI ID:6894435

Crill, P M; Martens, C S

Rates of sulfate reduction were measured over a 3 year period in the anoxic nearshore sediments of Cape Lookout Bight, North Carolina, using both a tube incubation method and a /sup 35/S-sulfate direct injection technique. The methods yielded similar depth-integrated rates over the upper 30 cm ranging from less than 10 mol SO/sub 4//sup =/ x m/sup -2/ x y/sup -1/ in winter to greater than 50 mol SO/sub 4//sup =/ x m/sup -2/ x y/sup -1/ in summer. There were also seasonal changes in the Arrhenius activation energies for the sulfate reduction rates indicating that the assumption that E/sub a/ is constant with temperature is not always valid. The time averaged annual turnover rate for all three years was 20.4 (+/- 11.4) mol SO/sub 4//sup =/ x m/sup -2/ x y/sup -1/. Surface rates ranged seasonally from less than 0.01 to over 3 mM SO/sub 4//sup =/ x d/sup -1/ between winter and summer, respectively. A subsurface rate maximum was observed to develop during the summer months which accounted for 28 percent of the annual depth-integrated sulfate reduction rate. Subsurface rate maxima are the result of changes in the chemistry (substrate type and/or concentration) and the microbiology in the sediments. The possibility of the subsurface maximum being an artifact of the /sup 35/S method is also discussed.

• Research Organization: Univ. of North Carolina, Chapel Hill (USA)
• OSTI ID: 6894435
• Journal Information: Geochim. Cosmochim. Acta; (United States), Journal Name: Geochim. Cosmochim. Acta; (United States) Vol. 51:5; ISSN GCACA
• Country of Publication: United States
• Language: English

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59 BASIC BIOLOGICAL SCIENCES
ACTIVATION ENERGY
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CHEMICAL REACTIONS
CHEMISTRY
CONTINENTAL MARGIN
CONTINENTAL SHELF
DIAGENESIS
ENERGY
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