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	A model of pycnocline thickness modified by the rheological properties of phytoplankton exopolymeric substances
	Jenkinson, Ian R.1,2; Sun, Jun1
刊名	JOURNAL OF PLANKTON RESEARCH
	2011-03-01
卷号	33期号:3页码:373-383
关键词	Rheology Phytoplankton Pycnocline Thin Layer Exopolymeric Substance Biogeochemistry
ISSN号	0142-7873
DOI	10.1093/plankt/fbq099
文献子类	Article
英文摘要	We model how phytoplankton-produced exopolymeric substances (EPS) may change pycnocline thickness delta z through control by Richardson number Ri. Shear stress tau(FORCED) is imposed across the pycnocline, giving a shear rate delta u/delta z, where delta u is cross-pycnocline velocity difference, modulated by viscosity eta. In natural waters, viscosity is composed of two components. The first is Newtonian, perfectly dispersed viscosity due to water and salts. The second is non-Newtonian, and depends on phytoplankton abundance raised to an exponent between +1.0 and +1.5. It is also generally shear-thinning, depending on (delta u/delta z)(P), where P is negative. In suspensions of microbial aggregates, viscosity depends also on (length scale)(d). Published measurements of EPS rheology in a culture of Karenia mikimotoi are input. These measurements were made at 0.5 mm, so they can be scaled to delta u/delta z if d is known for this EPS over the appropriate range of length scales. The model shows that delta u/delta z is very sensitive to d. At values of d <-0.2 or -0.3, however, high concentrations of K. mikimotoi (< 31 million L-1) have no significant effect on delta z at ambient values (> 1 cm). Future investigations of pycnocline dynamics should include measurements of rheological properties, and particularly d.; We model how phytoplankton-produced exopolymeric substances (EPS) may change pycnocline thickness delta z through control by Richardson number Ri. Shear stress tau(FORCED) is imposed across the pycnocline, giving a shear rate delta u/delta z, where delta u is cross-pycnocline velocity difference, modulated by viscosity eta. In natural waters, viscosity is composed of two components. The first is Newtonian, perfectly dispersed viscosity due to water and salts. The second is non-Newtonian, and depends on phytoplankton abundance raised to an exponent between +1.0 and +1.5. It is also generally shear-thinning, depending on (delta u/delta z)(P), where P is negative. In suspensions of microbial aggregates, viscosity depends also on (length scale)(d). Published measurements of EPS rheology in a culture of Karenia mikimotoi are input. These measurements were made at 0.5 mm, so they can be scaled to delta u/delta z if d is known for this EPS over the appropriate range of length scales. The model shows that delta u/delta z is very sensitive to d. At values of d <-0.2 or -0.3, however, high concentrations of K. mikimotoi (< 31 million L(-1)) have no significant effect on delta z at ambient values (> 1 cm). Future investigations of pycnocline dynamics should include measurements of rheological properties, and particularly d.
学科主题	Marine & Freshwater Biology ; Oceanography
URL标识	查看原文
语种	英语
WOS记录号	WOS:000287025500003
公开日期	2012-07-03
内容类型	期刊论文
源URL	[http://ir.qdio.ac.cn/handle/337002/11630]
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 Oceanol, Qingdao 266071, Peoples R China 2.Agence Conseil & Rech Oceanog, F-19320 Lavergne, Roche Canillac, France
推荐引用方式 GB/T 7714	Jenkinson, Ian R.,Sun, Jun. A model of pycnocline thickness modified by the rheological properties of phytoplankton exopolymeric substances[J]. JOURNAL OF PLANKTON RESEARCH,2011,33(3):373-383.
APA	Jenkinson, Ian R.,&Sun, Jun.(2011).A model of pycnocline thickness modified by the rheological properties of phytoplankton exopolymeric substances.JOURNAL OF PLANKTON RESEARCH,33(3),373-383.
MLA	Jenkinson, Ian R.,et al."A model of pycnocline thickness modified by the rheological properties of phytoplankton exopolymeric substances".JOURNAL OF PLANKTON RESEARCH 33.3(2011):373-383.

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