Adsorption into mineral mesopores as a stabilization mechanism for organic matter on aluminosilicates

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

OSTI ID:5973287

Mayer, L M ^[1]

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1. Univ. of Maine, Walpole, ME (United States). Dept. of Oceanography

Measurements of mineral specific surface area and total organic carbon (TOC) indicate that many marine shelf and estuarine sediments, and aluminosilicate soils, have a TOC content equivalent to a monolayer of organic matter covering all mineral surfaces. Density separations of discrete organic particulates from mineral-associated OC are consistent with a primarily adsorbed nature foremost of TOC. Nitrogen gas adsorption data also suggest extensive organic coatings on the mineral grains. Downcore analyses indicate that sediments with TOC starting in excess of monolayer-equivalent (ME) levels decay with core depth to the ME level and then markedly slow their OC loss rate--i.e., the ME level determines the refractory background concentration of TOC. Pore size distributions of marine sediments, determined by nitrogen adsorption or mercury porosimetry, indicate that most surface area of minerals is to be found in pores of < 10 nm diameter. These observations lead to the hypothesis that organic matter is stabilized on aluminosilicate minerals by adsorption into pores too small to allow entry or functioning of the hydrolytic enzymes responsible for OC degradation. This hypothesis is consistent with, but does not require, humification reactions as necessary for OC stabilization. The ME levels of TOC found in continental platform aluminosilicates hence represent a cap on the amount of organic matter that can be protected in this manner and thus attain a residence time of > 1,000 y. Stabilization of higher levels of TOC, as in acid soils or anoxic sediments, presumably results from protection by different mechanisms.

• OSTI ID: 5973287
• Report Number(s): CONF-921058-; CODEN: GAAPBC
• Journal Information: Geological Society of America, Abstracts with Programs; (United States), Vol. 24:7; Conference: 1992 annual meeting of the Geological Society of America (GSA), Cincinnati, OH (United States), 26-29 Oct 1992; ISSN 0016-7592
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
02 PETROLEUM
ORGANIC MATTER
ADSORPTION
SEDIMENTS
SORPTIVE PROPERTIES
ALUMINIUM SILICATES
CARBON
CONTINENTAL SHELF
ESTUARIES
MINERALS
PORE STRUCTURE
POROSITY
STABILIZATION
SURFACE AREA
ALUMINIUM COMPOUNDS
CONTINENTAL MARGIN
ELEMENTS
MATTER
MICROSTRUCTURE
NONMETALS
OXYGEN COMPOUNDS
SILICATES
SILICON COMPOUNDS
SORPTION
SURFACE PROPERTIES
SURFACE WATERS
580000* - Geosciences
020200 - Petroleum- Reserves
Geology
&amp; Exploration