Disintegration of calcite in dregs - metabolic disintegration .


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Dissolution of calcite in sediments -- metabolic dissolution. CaCO3 accumulation in marine sediments. CaCO3 is the predominant biogenic sediment constituent over much of the ocean Changes in the marine alkalinity budget can drive changes in atmospheric PCO2
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Slide 1

Disintegration of calcite in silt - metabolic disintegration

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CaCO3 aggregation in marine residue CaCO3 is the overwhelming biogenic dregs constituent over a great part of the sea Changes in the marine alkalinity spending plan can drive changes in barometrical PCO2 include changes in the amassing rate of CaCO3 in marine sediment ==> The investigation of environmental change is connected to the investigation of CaCO3 in marine sediments

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CaCO3 disintegration ~ half of calcite disintegration in the sea happens at the ocean bottom Up to half of ocean bottom calcite disintegration may happen in dregs that lie over the calcite immersion skyline … what drives this disintegration?

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"Metabolic" calcite disintegration Oxic breath brings about the arrival of acids to arrangement : Acids are killed by (and comparative responses for killing H + )

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Sediments versus water segment In the water segment, A substantial repository of broke up CO 3 2-, B(OH) 4 - … consequence of breath: lower pH and CO 3 2-in profound water over its ~ 1000 yr trip from NAtl to NEPac How are silt distinctive? spatial scale… 8 cm blended layer, w~1cm/ky… res time ~ 8000 y \ supply of broke up CO 3 2-, B(OH) 4 - constrained by dissemination from BW Abundant CaCO 3 (s) in residue ==> Dissolution is supported in dregs if pore waters are driven to undersaturation

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Theoretical thought of metabolic disintegration

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Predicted [CO 3 2-] versus profundity General… A particular case, supersaturated base water…

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Evidence - Solid stage Measurements Of %CaCO3 in NA silt Calcite sat. skyline

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Evidence - Pore water Organic matter oxidation by O2: With no disintegration: With disintegration, add to this response: Now:

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Review: oxic digestion system and calcite disintegration C organization CaCO 3 Net Alk flux out No net Alk flux equilibration disintegration Fluxes of solids: strong lines Fluxes of solutes: dashed lines

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Pore waters from Atlantic Both above and underneath CSH Lines: anticipated, with dissolution

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Evidence - Pore water In situ microelectrode profiling ** measure pore water pH and O2 at high determination ** translate profiles utilizing a model of coupled oxic digestion system/calcite disintegration ** the blend permits (1) subjective exhibition of metabolic disintegration (2) evaluation of disintegration rate

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Metabolic disintegration : models For every solute: Assume: corrosive base harmony in arrangement ! For CaCO 3 : For mass: Where: Assume: no calcite precipitation !

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Supersaturated bw Undersat.

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In situ MEP Archer et al. (1989) GCA 53, 2831-2845 Data from: Station 12 - above CSH Station 13 - underneath CSH

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pH, displayed to give Calcite disintegration rate O 2 , demonstrated to give rate of Corg bull versus profundity 12 13 Curves = dif. Corg rain rates Dash: diff. calcite sat.

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In situ MEP North Atlantic Hales et al., 1994, DSR 41, 695-719 From 2 destinations: 5 - 2159m 7 - 4236m

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With NO disintegration Clear exhibit that disintegration must happen … if model is right! Evaluation of disintegration by attacks of model yield to pH information

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Evidence - Pore water in situ entire center crushing Martin and Sayles, 1996, GCA 60, 243-263 In situ estimation of pore water TCO 2 , Alk, Ca 2+ … exhibit of disintegration without model Either shipboard or in situ estimation of NO 3 - , shipboard O 2 … measurement of bull. versus profundity Model of coupled C organization bull. what\'s more, calcite disintegration to measure disintegration rate

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Ceara Rise, w. tropical Atlantic Site A: simply above CSH

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Ceara Rise, Site An In all: lines are attacks of model to information to compel fluxes and parameter values

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second in situ wcs result - Cape Verde Plateau, E. tropical Atlantic well above CSH Lines = attacks of model to information to measure disintegration rate

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Pore water prove - carbon isotopes McCorkle The  13 C of pore water TCO 2 Organic carbon ~ - 20 ‰ CaCO 3 ~ 0‰ disintegration breath Pore water DIC its  13 C mirrors the extents of the 2 forms

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Note: think about shipboard and in situ examining

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Summary McCorkle isotopic information

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Summary Pore water pH, Alk, TCO 2 information

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Counter proof? In situ benthic flux chambers Jahnke & Jahnke, 2004, GCA 68, 47-59 Above CSH Below CSH Alk Ca

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Summary Benthic flux chamber information ? No disintegration in residue with %CaCO3 > 30%? - ? precipitation at interface? - ? Mistaken speciation demonstrate - calcite surface science - - ? On the other hand are chambers just not sufficiently delicate

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One more approach - 230 Th action changes close swi Martin, 2004

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Best place to watch this impact: destinations with high %CaCO 3 Ontong-Java Plateau

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Bottom water immersion state %CaCO 3

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If metabolic disintegration happens, how vital is it? 2 contending forms: diffusion crosswise over dregs water interface CaCO 3 disintegration Balance between them relies on upon: Ratio, Corg rain : CaCO3 rain - today, steady at ~ 0.8 depth conveyance of Corg oxidation in silt saturation condition of base water

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Depth circulation of Corg oxidation in residue in the remote ocean Martin and Sayles (2006) DSR II, 53, 771-792 Then "e-collapsing profundity is 1/p 1 If

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How does metabolic disintegration shift with profundity appropriation of oxidation and immersion state? Show test: Keep C organization and CaCO 3 rain rates steady, differ sat. condition of bw and e-overlap profundity of oxidation

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What is a "best figure" of metabolic disintegration - rain rate proportion consistent at ~ 0.8 - watched Corg bull. Conveyance in residue Dissolution rate increments with Increasing precipitation at given immersion CaCO3 internment proficiency is ~ steady At given sat., however diminishes with Decreasing bw. immersion "mde" ~ steady at given sat., But increments as sat. diminishes

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