an integrative view of the biological carbon pump
DESCRIPTION
An integrative view of the biological carbon pump. from the surface ocean to the deep sediment. Controls importance of global ocean & sediments as C sink (or source) temporal sequestration of C in deep ocean (very fast response) CH 2 O burial (fast response) - PowerPoint PPT PresentationTRANSCRIPT
An integrative view of the biological carbon pumpfrom the surface ocean to the deep sediment
Sandra Arndt ([email protected])
Sandra Arndt ([email protected])
The biological C pump
•Controls importance of global ocean & sediments as C sink (or source)
temporal sequestration of C in deep ocean (very fast response)CH2O burial (fast response)weathering-CaCO3 burial (slow response)
•Controls atmospheric O2
•Controls nutrient and O2 distribution in the ocean
•Controls size of hydrocarbon reservoirs
Sandra Arndt ([email protected])
Efficiency of the biological C pump
Euphotic/Epipelagic zone (0-200m)
Fexport=10-20% NPP
10-1 yrs
103 yrsDeposition flux
Sediment (0-103-104m)
Mesopelagic zone (200-1000m)
Bathypelagic zone (1000-4000m)
Abyssopelagic zone (4000-6000m)
0 yrs
108 yrs
0.28-30% Fexport
<1-5% Fexport
<0.3% Fexport
CH2O
Fexport=100% NPP
Burial flux
70% Fexport
50% Fexport
13% Fexport
CaCO3
Export flux
Sandra Arndt ([email protected])
Spatial variability- Global scale
Henson et al., 2012 Henson et al., 2012
Henson et al., 2012Seiter et al., 2004
Primary Production (gC m-2 yr-1) Export Efficiency Peff=Fexport/PP
Transfer Efficiency Teff=F2000m/Fexport
Sediment TOC (wt%)
Sandra Arndt ([email protected])
Spatial variability- Global scale
Arndt et al., ESR, in press
Regional patterns of organic matter quality in surface sediments
Sandra Arndt ([email protected])
Spatial variability- Global scale
Seiter et al., 2005
Hensen et al., 1998
PO4 flux(mmol m-2 yr-1)
NO3 flux(mmol m-2 yr-1)
Sandra Arndt ([email protected])
Spatial variability- Continental Margin
Arndt et al., in press
Mollenhauer and Eglinton, 2007
Lateral transport
Sandra Arndt ([email protected])
Spatial variability- Lateral Transport
Schmidt et al., 2007
Marine-dominated inner shelf
Terrestrial mud dominated mid-shelfmudbelt
Starved outer shelf and continental slope
Sandra Arndt ([email protected])
Spatial Variability- Continental Margin
Zabel and Hensen, 2006 (modified from Jahnke, 1990)
Sediments are the ultimate sediment trap!
Sandra Arndt ([email protected])
Temporal variability-Seasonal variability
Lutz et al., 2007
Seasonal variability NPP:Low: Equ. low productivity regions
High: high latitudes, monsoonal and temperate high productivity regions
Balance between seasonality of flux and production reverses with latitude
Sandra Arndt ([email protected])
Temporal variability-Seasonal variability
Soetaert et al., 1996
Seasonal variability in CH2O input results in a complex benthic response
Sandra Arndt ([email protected])
Temporal variability-Lessons from the past
Example: 1. Pliocene-Pleistocene Transition at Bowers Ridge (Beringsea)
Sandra Arndt ([email protected])
Temporal variability-Lessons from the past
Wehrmann et al., 2013
Inverse diagenetic modeling of sediment porwater profiles…
…indicates peak in CH2O deposition flux & quality across transition and thus important changes in the functioning of the BCP
Sandra Arndt ([email protected])
Temporal variability-Lessons from the past
Example: 2. Cretaceous Oceanic Anoxic Event
Greenhouse climate, anoxic/sulfidic ocean
Sandra Arndt ([email protected])
Temporal variability-Lessons from the past
Arndt et al., 2009
Inverse diagenetic modeling of sediment porwater profiles indicates low reactivity (high preservation efficiency) and thus rapid transfer from surface ocean to deep sediment
Sandra Arndt ([email protected])
What causes the spatial-temporal variability?
The efficiency of the biological C pump is mainly driven by the production, transport and alteration of POC
Sandra Arndt ([email protected])
What causes the spatial-temporal variability?
1. Ballasting
Model that partitions sinking CH2O in two fractions:
1) ballast associated2) unassociated
Sarmiento and Gruber, 2006
Sandra Arndt ([email protected])
What causes the spatial-temporal variability?
1. BallastingSpatial variability of CaCO3 carrying coefficients
Wilson et al., 2012
Sandra Arndt ([email protected])
What causes the spatial-temporal variability?
2. Ecosystem Structure
Effect on transport Effect on quality
Micklasz and Denny, 2010
Mayor et al., 2012
Sandra Arndt ([email protected])
What causes the spatial-temporal variability?
3. Organic matter source and transport
High quality:Young marine material
Low quality:Old marine materialMix pre-aged, terrestrial material
Arndt et al., in press
Sandra Arndt ([email protected])
Representation of the pump in Earth System Models
Arndt et al., in press(adapted from lutz et al., 2002)
•Flux:
Simple power-law expression with constant scaling factor (Martin curve, Martin, 1987):
Limit ability of models to predict response of the BCP to environmental perturbations and climate change
•no sediments€
F(z) = Fexp⋅z
z0
⎛
⎝ ⎜
⎞
⎠ ⎟
b
Sandra Arndt ([email protected])
Conclusions
Biological carbon pump is a complex set of interlinked processes that act along the surface ocean- deep sediment continuum
Its functioning and efficiency is highly variable in time and space with important implications for global climate and biogeochemical cycles
Existing Earth system models include empirical, highly simplified and decoupled representations of the biological carbon pump that are not related to factors that control the quantity and quality of the flux
