A model of pycnocline thickness modified by the rheological properties of phytoplankton exopolymeric substances

doi:10.1093/plankt/fbq099

	A model of pycnocline thickness modified by the rheological properties of phytoplankton exopolymeric substances
	Jenkinson, Ian R.1,2; Sun, Jun 1
	2011-03-01
发表期刊	JOURNAL OF PLANKTON RESEARCH
ISSN	0142-7873
卷号	33 期号:3 页码:373-383
文章类型	Article
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.
关键词	Rheology Phytoplankton Pycnocline Thin Layer Exopolymeric Substance Biogeochemistry
学科领域	Marine & Freshwater Biology ; Oceanography
DOI	10.1093/plankt/fbq099
URL	查看原文
收录类别	SCI
语种	英语
WOS记录号	WOS:000287025500003
引用统计	被引频次：6[WOS] [WOS记录] [WOS相关记录]
文献类型	期刊论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/11629
专题	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
第一作者单位	中国科学院海洋研究所
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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A model of pycnoclin（314KB）			限制开放	--	浏览