Oxic microzones and radial oxygen loss from roots of Zostera marina

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dc.contributor.author Jensen, SI
dc.contributor.author Kühl, M
dc.contributor.author Glud, RN
dc.contributor.author Jørgensen, LB
dc.contributor.author Priemé, A
dc.date.accessioned 2012-02-02T07:23:18Z
dc.date.issued 2005-06-02
dc.identifier.citation Marine Ecology Progress Series, 2005, 293 pp. 49 - 58
dc.identifier.issn 0171-8630
dc.identifier.other C1UNSUBMIT en_US
dc.identifier.uri http://hdl.handle.net/10453/14873
dc.description.abstract Oxygen microelectrodes and planar oxygen optodes were used to map the microdistribution of oxygen and the radial oxygen loss (ROL) from roots of Zostera marina kept in natural sediment, Substantial heterogeneity in the oxygen distribution was seen along the roots, with oxygen mainly leaking out from the root tips. Maximum oxygen levels at the root surface reached 19 to 80 % of air saturation in the light and the oxygenated zone extended 1 to 2 mm away from the root tip. The oxygen concentration at the root surface decreased to 0-5 % of air saturation at positions 3 to 6 mm behind the root apex. The high oxygen levels at the root tip surface were due to an effective barrier to ROL on the older part of the roots and the presence of an effective gas-transport system in the plant, with numerous intercellular spaces extending very close to the apical meristem of the root. Radial diffusion of oxygen from the root surface created a dynamic 0 to 1 mm-wide oxic microzone around the ∼0.3 mm wide roots of Z. marina that varied with irradiance and distance from the root tip. Root-surface oxygen concentrations and ROL measured 2 mm behind the apex increased with increasing irradiance until ROL saturation was reached at irradiances >400 μmol photons m-2 s-1. The ROL increased from 16.2 nmol O2 cm-2 h-1 in darkness to 21.6, 28.8 and 36.0 nmol O2 cm-2 h -1 at incident irradiances of 25, 111 and 467 μmol photons m -2 s-1, respectively. Based on measured steady-state radial oxygen profiles, the total oxygen export from one 6 cm long root of the first actively growing root bundle with a total surface area of 0.56 cm 2 was estimated to be 6.0 to 6.7 nmol O2 h-1 in saturating light. The total subsurface input of plant-mediated oxygen was estimated to be only in the order of 2 to 14 % of the total diffusive oxygen uptake (DOU) across the sediment-water interface. The local input of oxygen from the root tip was, however, similar to the DOU at the primary sediment-water interface, and 35 to 43 % of the total oxygen loss occurred from the outermost 0 to 3.5 mm of the root tip. The roots of Z. marina grow ∼5 mm d -1, and significant oxygen levels will therefore only be present at a given spot for less than 24 h during root growth. The rhizosphere of Z. marina is thus characterised by a constantly changing mosaic of ephemeral oxic microniches in the reduced sulphidic sediment, leaving behind an anoxic but oxidised zone around the more mature parts of the roots. © Inter-Research 2005.
dc.language eng
dc.title Oxic microzones and radial oxygen loss from roots of Zostera marina
dc.type Journal Article
dc.description.version Published
dc.parent Marine Ecology Progress Series
dc.journal.volume 293
dc.journal.number en_US
dc.publocation Germany en_US
dc.identifier.startpage 49 en_US
dc.identifier.endpage 58 en_US
dc.cauo.name SCI.Environmental Sciences en_US
dc.conference Verified OK en_US
dc.for 0602 Ecology
dc.personcode 107129
dc.percentage 100 en_US
dc.classification.name Ecology en_US
dc.classification.type FOR-08 en_US
dc.edition en_US
dc.custom en_US
dc.date.activity en_US
dc.location.activity en_US
dc.description.keywords Microelectrodes
dc.description.keywords Optodes
dc.description.keywords Radial oxygen loss
dc.description.keywords Rhizosphere
dc.description.keywords Zostera marina
pubs.embargo.period Not known
pubs.organisational-group /University of Technology Sydney
pubs.organisational-group /University of Technology Sydney/Faculty of Science
pubs.organisational-group /University of Technology Sydney/Strength - C3
utslib.copyright.status Open Access
utslib.copyright.date 2015-04-15 12:23:47.074767+10
pubs.consider-herdc false
utslib.collection.history General (ID: 2)

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