Bioturbation and remineralization of sedimentary organic matter

Conference · Wed Jan 01 04:00:00 EST 1992 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5930184

Aller, R C ^[1]

---

1. State Univ. of New York, Stony Brook, NY (United States). Marine Sciences Research Center

A variety of field and laboratory observations demonstrate that particle reworking and irrigation activities of benthic fauna promote the remineralization of organic matter. Of the many simultaneous factors involved, two may be particularly important: (1) repetitive oscillation of redox conditions in the bioturbated zone, and (2) low metabolite build-up. In bioturbated C-rich deposits with restricted O[sub 2] penetration, particles constantly cycle between oxic and anoxic zones but typically spend 10--100X longer under anoxic than oxic conditions. Experimental evidence and theoretical considerations indicate that even brief, periodic re-exposure to O[sub 2] results in more complete and sometimes rapid decomposition than is possible under constant redox conditions. Remineralization of N (and probably C) is also enhanced by solute exchange associated with biogenic or physical irrigation of sediments. Diffusion experiments simulating different irrigated burrow densities demonstrate that diffusively open sediments at quasi-steady state sustain higher net NH[sub 4][sup +] production rates than closed systems and have greater losses to overlying water. Substantial elevation in net production occurs as effective burrow abundance increases to extreme levels. Periodically ventilated anoxic incubations also show enhanced rates of remineralization. Lack of biological reincorporation of solutes at low concentrations can sometimes explain net rate increases. The effects of mixing and particle manipulation on decomposition are probably often confounded with the effect of metabolite dilution during experiments with sediment suspensions. It is still not know from short-term experiments whether the time-integrated, total amount of organic matter remineralization differs in the presence or absence of macrofauna but the sedimentary record suggests the proportion preserved is decreased.

• OSTI ID: 5930184
• Report Number(s): CONF-921058--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 24:7
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200 -- Petroleum-- Reserves
Geology
& Exploration
58 GEOSCIENCES
580000* -- Geosciences
BIODEGRADATION
CHEMICAL REACTIONS
DECOMPOSITION
MATTER
MICROORGANISMS
MINERALIZATION
ORGANIC MATTER
OXIDATION
ROCKS
SEDIMENTARY ROCKS