Role of sedimentary organic matter in bacterial sulfate reduction: the G model tested

Journal Article · Thu Mar 01 00:00:00 EST 1984 · Limnol. Oceanogr.; (United States)

DOI:https://doi.org/10.4319/lo.1984.29.2.0236· OSTI ID:6540357

Westrich, J T; Berner, R A

Laboratory study of the bacterial decomposition of Long Island Sound plankton in oxygenated seawater over a period of 2 years shows that the organic material undergoes decomposition via first-order kinetics and can be divided into two decomposable fractions, of considerably different reactivity, and a nonmetabolized fraction. This planktonic material, after undergoing varying degrees of oxic degradation, was added in the laboratory to anoxic sediment taken from a depth of 1 m at the NWC site of Long Island Sound and the rate of bacterial sulfate reduction in the sediment measured by the /sup 35/S radiotracer technique. The stimulated rate of sulfate reduction was in direct proportion to the amount of planktonic carbon added. This provides direct confirmation of the first-order decomposition, or G model, for marine sediments and proves that the in situ rate of sulfate reduction is organic-matter limited. Slower sulfate reduction rates resulted when oxically degraded plankton rather than fresh plankton was added, and the results confirm the presence of the same two fractions of organic matter deduced from the oxic degradation studies. Near-surface Long Island Sound sediment, which already contains abundant readily decomposable organic matter, was also subjected to anoxic decomposition by bacterial sulfate reduction. The decrease in sulfate reduction rate with time parallels decreases in the amount of organic matter, and these results also indicate the presence of two fractions of organic carbon of distinctly different reactivity. From plots of the log of reduction rate vs. time two first-order rate constants were obtained that agree well with those derived from the plankton addition experiment. Together, the two experiments confirm the use of a simple multi-first-order rate law for organic matter decomposition in marine sediments.

• Research Organization: Yale Univ., New Haven, CT (United States)
• OSTI ID: 6540357
• Journal Information: Limnol. Oceanogr.; (United States), Vol. 29:2
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
ORGANIC MATTER
DECOMPOSITION
SULFATES
BIODEGRADATION
KINETICS
LONG ISLAND SOUND
MATHEMATICAL MODELS
PLANKTON
SEDIMENTS
SULFATE-REDUCING BACTERIA
SULFUR 35
TRACER TECHNIQUES
AQUATIC ORGANISMS
ATLANTIC OCEAN
BACTERIA
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CHEMICAL REACTIONS
DAYS LIVING RADIOISOTOPES
ESTUARIES
EVEN-ODD NUCLEI
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
MICROORGANISMS
NUCLEI
OXYGEN COMPOUNDS
RADIOISOTOPES
SEAS
SULFUR COMPOUNDS
SULFUR ISOTOPES
SURFACE WATERS
550701* - Microbiology- Tracer Techniques
550200 - Biochemistry