Presentation on theme: "Carbon and biogeochemistry of the sea ice zone Bates et al., (2006) Stephens and Keeling (2002) Sigman et al., (2010) Takahashi et al., (2009) Arrigo et."— Presentation transcript:
Carbon and biogeochemistry of the sea ice zone Bates et al., (2006) Stephens and Keeling (2002) Sigman et al., (2010) Takahashi et al., (2009) Arrigo et al., (2010) McNeil et al., (2007)
Ventilation and subduction in the sea ice zone (Arctic) Steele et al., (1995) AW = Atlantic water ASW = Arctic surface water CDW = Cold deep water CHW = Cold halocline water
DIC Pump Hypothesis Mirabilite crystals Na 2 SO 4 ·10H 2 O (Arctic sea ice) Ikaite crystals CaCO 3 ·6H 2 O (Weddell Sea ice) (Light et. al, 2003) (Dieckmann et. al, 2008) DIC pump Alk. flux ?
DIC Pump Hypothesis DIC pump Alk. flux ? Zero sum gain scenario
CO 2 rectification hypothesis (Yager et al., 1995) Export production? Alk. flux ? CO 2 flux ?
Springtime fluxes (S.O.) Export production? Alk. flux ? CO 2 flux ? Loose et al., (2011) Net CO 2 flux into mixed layer = Primary production – Gas exchange + upwelling* Gas exchange (k) is usually inferred, rarely measured. We need to measure Primary production + gas exchange at the same time in the SIZ.
Do we have estimates of k in sea ice cover and do we believe them? Fanning and Torres (1991) Loose and Schlosser (2011)
Air-sea gas exchange depends on aqueous turbulence Shear in the ice-ocean boundary layer (IOBL) (McPhee, 1992; McPhee, 2008, Andreas, 1986). Buoyant convection/stratification (Lombardo and Gregg, 1989; Morison et al., 1992) Short-period wind waves (Frew et al., 2004) and their interactions with ice floes
How to measure gas exchange on MOSAiC? Smethie et al., (1985), Peng et al., (1979) 226 Ra originates in the sediments and bedrock. 226 Ra decays to 222 Rn. 222 Rn has 3.8 day half-life.
5. How to measure gas exchange and primary production together? National Geographic Δ(O 2 /Ar) Method: Ar behaves like abiotic O 2 Solubility of Ar ~ Solubility of O 2 Diffusivity of Ar ~ Diffusivity of O 2 Δ(O 2 /Ar) reflects excess oxygen of biogenic origin. Net Community O2 production (NCP) = k ρΔ( O2/Ar)