Cross-shelf biogeochemical characteristics of sediments in the central Benguela and their relationship to overlying water column hypoxia

dc.contributor.authorVan der Plas, A K
dc.contributor.authorMonteiro, P M S
dc.contributor.authorPascall, A
dc.date.accessioned2018-01-30T08:53:32Z
dc.date.available2018-01-30T08:53:32Z
dc.date.issued2007
dc.date.updated2016-01-22T09:34:21Z
dc.description.abstractData from two cross-shelf sediment sampling cruises were used to explain reasons for the sediment biogeochemical variability in respect of carbon, nitrogen and sulphur, and how the cycling of these elements governs the biogeochemistry of the overlying water through their control of the redox conditions. The spatial extent of this benthic–pelagic flux link is limited to the innershelf mud belt system on the Namibian shelf. The inshore mud belt is the primary deposition area of the carbon and nitrogen new production export flux. The offshore organic-rich zones are thought to be relict particulate organic matter originating from the inshore mud belt rather than from an overlying pelagic source. These data were used to set up a multi-layer sediment model that was used through sensitivity analyses to elucidate the input characteristics that result in the most significant feedbacks on hypoxia in the overlying water. The analyses showed that, although the new production flux is a requirement to drive an oxygen demand in the sediments, the onset and persistence of anoxia may depend critically on a low-oxygen boundary condition threshold. This is thought to be a key differentiating factor between systems that, despite comparable carbon export fluxes, are characterised by a persistent hypoxia/anoxia signal and those that are characterised by episodic hypoxia events. It was concluded that sediment oxygen demand and methane and 'sulphide' emissions from the central Benguela sediments are responses to external hypoxia boundary conditions rather than the local drivers of oxygen variability.
dc.identifierhttp://dx.doi.org/10.2989/AJMS.2007.29.1.3.68
dc.identifier.apacitationVan der Plas, A. K., Monteiro, P. M. S., & Pascall, A. (2007). Cross-shelf biogeochemical characteristics of sediments in the central Benguela and their relationship to overlying water column hypoxia. <i>African Journal of Marine Science</i>, http://hdl.handle.net/11427/27081en_ZA
dc.identifier.chicagocitationVan der Plas, A K, P M S Monteiro, and A Pascall "Cross-shelf biogeochemical characteristics of sediments in the central Benguela and their relationship to overlying water column hypoxia." <i>African Journal of Marine Science</i> (2007) http://hdl.handle.net/11427/27081en_ZA
dc.identifier.citationVan der Plas, A. K., Monteiro, P. M. S., & Pascall, A. (2007). Cross-shelf biogeochemical characteristics of sediments in the central Benguela and their relationship to overlying water column hypoxia. African Journal of Marine Science, 29(1), 37-47.
dc.identifier.ris TY - Journal Article AU - Van der Plas, A K AU - Monteiro, P M S AU - Pascall, A AB - Data from two cross-shelf sediment sampling cruises were used to explain reasons for the sediment biogeochemical variability in respect of carbon, nitrogen and sulphur, and how the cycling of these elements governs the biogeochemistry of the overlying water through their control of the redox conditions. The spatial extent of this benthic–pelagic flux link is limited to the innershelf mud belt system on the Namibian shelf. The inshore mud belt is the primary deposition area of the carbon and nitrogen new production export flux. The offshore organic-rich zones are thought to be relict particulate organic matter originating from the inshore mud belt rather than from an overlying pelagic source. These data were used to set up a multi-layer sediment model that was used through sensitivity analyses to elucidate the input characteristics that result in the most significant feedbacks on hypoxia in the overlying water. The analyses showed that, although the new production flux is a requirement to drive an oxygen demand in the sediments, the onset and persistence of anoxia may depend critically on a low-oxygen boundary condition threshold. This is thought to be a key differentiating factor between systems that, despite comparable carbon export fluxes, are characterised by a persistent hypoxia/anoxia signal and those that are characterised by episodic hypoxia events. It was concluded that sediment oxygen demand and methane and 'sulphide' emissions from the central Benguela sediments are responses to external hypoxia boundary conditions rather than the local drivers of oxygen variability. DA - 2007 DB - OpenUCT DP - University of Cape Town J1 - African Journal of Marine Science LK - https://open.uct.ac.za PB - University of Cape Town PY - 2007 T1 - Cross-shelf biogeochemical characteristics of sediments in the central Benguela and their relationship to overlying water column hypoxia TI - Cross-shelf biogeochemical characteristics of sediments in the central Benguela and their relationship to overlying water column hypoxia UR - http://hdl.handle.net/11427/27081 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/27081
dc.identifier.vancouvercitationVan der Plas AK, Monteiro PMS, Pascall A. Cross-shelf biogeochemical characteristics of sediments in the central Benguela and their relationship to overlying water column hypoxia. African Journal of Marine Science. 2007; http://hdl.handle.net/11427/27081.en_ZA
dc.language.isoeng
dc.publisher.departmentDepartment of Oceanographyen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.sourceAfrican Journal of Marine Science
dc.source.urihttp://www.tandfonline.com/loi/tams20
dc.subject.otheranoxia
dc.subject.otherBenguela Current
dc.subject.othercarbon
dc.subject.otherhypoxia
dc.subject.othermodelling
dc.subject.otherNamibia
dc.subject.othersediment biogeochemistry
dc.titleCross-shelf biogeochemical characteristics of sediments in the central Benguela and their relationship to overlying water column hypoxia
dc.typeJournal Article
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