The acoustic turbid layer in muddy sediments of Eckernfoerde Bay, Western Baltic: methane concentration, saturation and bubble characteristics.

Abegg, Friedrich and Anderson, Aubrey L. (1997) The acoustic turbid layer in muddy sediments of Eckernfoerde Bay, Western Baltic: methane concentration, saturation and bubble characteristics. Marine Geology, 137 (1-2). pp. 137-147. DOI 10.1016/S0025-3227(96)00084-9.

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Supplementary data:

Abstract

In Eckernfoerde Bay in the western Baltic, an enclosed basin with organic-rich mud, acoustic turbidity has been observed since 1952. To investigate the relationships between acoustic properties and free gas we developed a method for rapid sub-sampling of gravity cores to determine the total methane content. From temperature measurements, determinations of the salinity of the pore water and data from the literature, saturation limits were calculated for each core. It is demonstrated that there is a certain amount of free gas in the mud of Eckernfoerde Bay but subbottom depths of the oversaturation and of the acoustic turbidity do not correspond.

The existence of free gas implies the existence of bubbles in the sediment which are regarded to be responsible for the acoustic turbidity. Bubble sizes observed by X-ray computed tomography while still under in situ pressure and temperature vary between 1 and 10 mm equivalent diameter. The distribution of bubbles is discontinuous, occurring in depth zones from 2 to 20 cm thickness.

Document Type: Article
Additional Information: WOS:A1997WR72600012
Keywords: acoustic turbidity; methane saturation; sediment gas bubbles; Eckernforde Bay; tomography
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1016/S0025-3227(96)00084-9
ISSN: 0025-3227
Projects: Boknis Eck
Date Deposited: 16 Jul 2013 13:09
Last Modified: 16 Jul 2013 13:09
URI: http://oceanrep.geomar.de/id/eprint/21568

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