Diagenesis water column

The number of injectors required may be estimated in a similar manner, but it is unlikely that the exploration and appraisal activities will have included injectivity tests, of say water injection into the water column of the reservoir. In this case, an estimate must be made of the injection potential, based on an assessment of reservoir quality in the water column, which may be reduced by the effects of compaction and diagenesis. Development plans based on water injection or natural aquifer drive often suffer from lack of data from the water bearing part of the reservoir, since appraisal activity to establish the reservoir properties in the water column is frequently overlooked. In the absence of any data, a range of assumptions of injectivity should be generated, to yield a range of number of wells required. If this range introduces large uncertainties into the development plan, then appraisal effort to reduce this uncertainty may be justified. 

Ingall, E. and Jahnke, R. (1997). Influence of water-column anoxia on the elemental fractionation of carbon and phosphorus during sediment diagenesis. Mar. Geol. 139, 219-229. 

Measurements of radionuclides and metals in marine sediments and particulate matter are conducted for a variety of purposes, including the determination of sedimentation rates, trace metal and radionuclide fluxes through the water column, enrichment of metals in specific phases of the sediments, and examination of new sedimentary phases produced after sediment deposition. Such studies address fundamental questions concerning the chronology of deep-sea and near-shore sedimentary deposits, removal mechanisms and cycling of metals in the ocean, and diagenesis within deep-sea sediments. 

Deposition during the mixed period (up to day 165) was calculated from a mass balance on water-column Si and the Si P ratio in sediment trap material, because sediment traps overestimate the net particle deposition flux in a mixing water column (19). Our calculations assumed that losses of dissolved reactive Si resulting from diatom uptake that are not accounted for by increases in particulate biogenic Si are caused by Si deposition. The estimate of mixed-period P deposition was conservative because we assumed that nondiatom particulate P was removed at a rate similar to diatom P. We also assumed that loss of P in traps resulting from diagenesis-dissolution was negligible. The use of short collection periods (2-3 weeks) and a poison should minimize loss. 

Selective diagenesis and recycling of P during the summer months resulted in the replenishment of the colloidal fraction to enrichment levels above spring values (see mid-July data). However, colloid mass concentrations were lower in midsummer than in spring. The size of the colloidal-P pool actually declined in the main water column during midsummer. The colloidal-P pool represents a major component of the P cycle. However,... 

This paper describes the sulfur cycle for little Rock Lake, Wisconsin, with particular emphasis on processes that remove sulfate from the water column and on subsequent diagenesis and regeneration. Our work and other recent studies in this area show that the classical paradigm of sulfur cycling (20) in lakes is incorrect, or at least incomplete. 

Kawamura, K., Ishiwatari, R., and Ogura, K. (1987) Early diagenesis of organic matter in the water column and sediments microbial degradation and resynthesis of lipids in Lake Haruna. Org. Geochem. 11, 251-264. 

The formation of marine sediments depends upon chemical, biological, geological and physical influences. There are four distinct processes that can be readily identified. Firstly, the source of the material obviously is important. This is usually the basis for classifying sediment components and will be considered below in more detail. Secondly, the material and its distribution on the ocean floor are influenced by its transportation history, both to and within the ocean. Thirdly, there is the deposition process that must include particle formation and alteration in the water column. Finally, the sediments may be altered after deposition, a process known as diagenesis. Of particular importance are reactions leading to changes in the redox state of the sediments. 

Harvey H. R. and Macko S. A. (1997) Catalysts or contributors tracking bacterial mediation of early diagenesis in the marine water column. Org. Geochem. 26(9/10), 531-544. 

Roughly 90% of the organic matter that exits the euphotic zone of the ocean is degraded in the water column. Of the 10% of the organic carbon flux that reaches the seafloor, only about one-tenth escapes oxidation and is buried. Degradation of the organic matter that reaches the ocean sediments drives the reactions that control sediment diagenesis and benthic flux. 

Effects of Water-column Recycling and Sediment Diagenesis on the Alkenone Unsaturation Index... 

Alkenones appear recalcitrant to diagenesis in the water column and within sediments relative to other large macromolecules. Indeed, the first reported occurrence of alkenones came not from recent material, but from Miocene age sediments of the Walvis Ridge (Boon et al., 1978). Shortly thereafter, these compounds were linked to modem haptophyte algae, principally Emiliania huxleyi (de Leeuw et al., 1980 Volkman et al., 1980a,b Marlowe et al., 1984a,b). Reviews of... 

The Diagenesis of Biogenic Silica Chemical Transformations Occurring in the Water Column, Seabed, and Crust... 

Grantham et al., 1980 Schoell et ai, 1992). The association between these compounds and evidence of sulfidic water columns is very strong. Furthermore, it is not easy to rationalize how these compounds could arise by diagenesis of known BHP precursors. Thus, their occurrence is an indicator that some, presently unidentified, bacteria specific to these environments are the ultimate source and we predict they will be found in due course. 

Mobilization of sedimentary phosphorus by microbial activity during diagenesis causes dissolved phosphate buildup in sediment pore waters, promoting benthic efflux of phosphate to bottom waters or incorporation in secondary authigenic minerals. The combined benthic flux from coastal (sFcbf) and abyssal (sFabf) sediments is estimated to exceed the total riverine-P flux (F24(d+p>) to the ocean. Reprecipitation of diagenetically mobilized phosphorus in secondary phases significantly enhances phosphorus burial efficiency, impeding return of phosphate to the water column (see Section 8.13.3.3.2). Both processes impact the... 

During very early diagenesis and, to some extent, in the water column, 2 key competing or fating reactions appear to direct subsequent alteration, i.e. allomerization versus loss of the 10-carbomethoxy moiety. 

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