Drag increase and drag reduction found in phytoplankton and bacterial cultures in laminar flow: Are cell surfaces and EPS producing rheological thickening and a Lotus-leaf Effect?

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	Drag increase and drag reduction found in phytoplankton and bacterial cultures in laminar flow: Are cell surfaces and EPS producing rheological thickening and a Lotus-leaf Effect?
	Jenkinson, Ian R.1,2; Sun, Jun 1,3
刊名	DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY
	2014-03-01
卷号	101 页码:216-230
关键词	Phytoplankton Rheology Turbulence Dissolved organic matter Oceanic microstructure Pycnocline
通讯作者	Jenkinson, IR (reprint author), Chinese Acad Sci, Inst Oceanog, Key Lab Marine Ecol & Environm Sci, 7 Nanhai Rd, Qingdao 266071, Peoples R China.
英文摘要	The laminar-flow viscosity of ocean and other natural waters consists of a Newtonian aqueous component contributed by water and salts, and a non-Newtonian one contributed mainly by exopolymeric polymers (EPS) derived largely from planktonic algae and bacteria. Phytoplankton and EPS form thin layers in stratified waters, often associated with density discontinuities. A recent model (Jenkinson and Sun, 2011. J. Plankton Res., 33, 373-383) investigated possible thalassorheological control of pycnocline thickness (PT) by EPS secreted by the harmful dinoflagellate Karenia mikimotoi. The model, based on published measurements of viscosity increase by this species, found that whether it can influence PT depends on the relationship between increased viscosity, deformation rates/stresses and length scale, which the present work has investigated. To do this, flow rate vs. hydrostatic pressure (and hence wall stress) was measured in cultures (relative to that in reference water) in capillaries of 5 radii 0.35-1.5 mm, close to oceanic-turbulence Kolmogorov length. We compared cultures of the potentially harmful algae, K. mikimotoi, Alexandrium catenella, Prorocentrum donghaiense, Skeletonema costatum, Phaeodactylum tricornutum and the bacterium Escherichia colt. Drag increase, ascribed to rheological thickening by EPS, occurred in the smallest capillaries, but drag reduction (DR) occurred in the largest ones. Since this occurred at Reynolds numbers Re too small for turbulence (or turbulent DR) to occur, this was laminar-flow DR. It may have been superhydrophobic DR (SDR), associated with the surfaces of the plankton and bacteria. SDR is associated with the self-cleaning Lotus-leaf Effect, in which water and dirt are repelled from surfaces bearing nm- to mu m-sized irregularities coated with hydrophobic polymers. Because DR decreased measured viscosity and EPS thickening increased it, we could not validate the model. DR, however, represents hitherto unknown phenomenon in the oceans. Along with rheological thickening, Laminar-Flow DR may represent a new tool for plankton to manage ambient flow fields. (C) 2013 Elsevier Ltd. All rights reserved.
学科主题	Oceanography
收录类别	SCI
语种	英语
WOS记录号	WOS:000334141700018
内容类型	期刊论文
源URL	[http://ir.qdio.ac.cn/handle/337002/24006]
专题	海洋研究所_海洋生态与环境科学重点实验室
作者单位	1.Chinese Acad Sci, Inst Oceanog, Key Lab Marine Ecol & Environm Sci, Qingdao 266071, Peoples R China 2.Agcy Consultat & Res Oceanog, F-19320 Lavergne, La Roche Canill, France 3.Tianjin Univ Sci & Technol, TEDA, Coll Marine Sci & Engn, Tianjin 300457, Peoples R China
推荐引用方式 GB/T 7714	Jenkinson, Ian R.,Sun, Jun. Drag increase and drag reduction found in phytoplankton and bacterial cultures in laminar flow: Are cell surfaces and EPS producing rheological thickening and a Lotus-leaf Effect?[J]. DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY,2014,101:216-230.
APA	Jenkinson, Ian R.,&Sun, Jun.(2014).Drag increase and drag reduction found in phytoplankton and bacterial cultures in laminar flow: Are cell surfaces and EPS producing rheological thickening and a Lotus-leaf Effect?.DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY,101,216-230.
MLA	Jenkinson, Ian R.,et al."Drag increase and drag reduction found in phytoplankton and bacterial cultures in laminar flow: Are cell surfaces and EPS producing rheological thickening and a Lotus-leaf Effect?".DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY 101(2014):216-230.