WHY DO SINKING MUCILAGE AGGREGATES ACCUMULATE IN THE WATER COLUMN

Citation
Al. Alldredge et Km. Crocker, WHY DO SINKING MUCILAGE AGGREGATES ACCUMULATE IN THE WATER COLUMN, Science of the total environment, 165(1-3), 1995, pp. 15-22
Citations number
28
Categorie Soggetti
Environmental Sciences
ISSN journal
00489697
Volume
165
Issue
1-3
Year of publication
1995
Pages
15 - 22
Database
ISI
SICI code
0048-9697(1995)165:1-3<15:WDSMAA>2.0.ZU;2-#
Abstract
The formation of nuisance scums of mucilage on the ocean surface requi res that the sinking mucilage aggregates which eventually form the scu ms first become neutrally buoyant so as to accumulate in the water col umn. We hypothesize that neutral buoyancy is attained by an aggregate sinking from a lower density surface layer into a higher density haloc line if some proportion of the aggregate's volume is occupied by lower density mucus which is resistant to diffusion of salts and water. A m odel, based on the porosities, excess densities, and sinking rates of natural diatom aggregates obtained empirically, demonstrates that only 0.5-2% of the volume of an aggregate need be occupied by mucus for it to attain neutral buoyancy and accumulate at even modest pycnoclines. The model predicts accumulations at vertical density gradients increa sing by only 1-3 sigma(t), similar to vertical changes in density prev iously observed at the depths of mucus accumulations in the Adriatic S ea.