Lecture 19 Redox Environments in the Oceans

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Lecture 19 Redox Environments in the Oceans
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Multi-colored sediments! Whats going on here???
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Aerobic Respiration in Red Clay Sediments
Murray and Grundmanis, 1980
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Denitrification and MnO2 reduction Hemipelagic
Sediments
Guatemala Basin, North Pacific
Emerson et al
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Iron reduction Hemipelagic Sediments
East Pacific Rise North Pacific
Emerson et al
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Saanich Inlet, BC Sediments
Sulfate Reduction Methane Production Anaerobic
Methane Consumption
Kuivila and Murray (1990)
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The Black Sea
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Why is the Black Sea Interesting to
Oceanographers?
1. The classic anoxic basin. Oxic layer over
sulfidic layer. 2.Model for modern and ancient
anoxic environments. 3. Well developed
transition or suboxic zone. Model for worlds
organic rich sediments. 4. Suboxic reactions
easy to study here because of predictable depth
locations. 5. An ideal location to study effect
of climate forcing on ocean distributions.
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The Bosporus Strait connects the Black Sea with
the Marmara Sea and is the only source of
(relatively warm) salty water.
Black Sea
Marmara Sea
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Temperature and Salinity along the Bosporus

• Some CIW advected into strait in upper half of
  interface
• T minimum in deep water erased over South Sill

Gregg et al (1999)
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Bosporus Inflow and Entrainment of CIL
CIL (from NW Shelf in winter)
Bosporus Inflow
CIL/BI 4 for deep Black Sea from 50m to 2000m
from Ozsoy et al.,(1993)
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The Suboxic Zone Oxygen Sulfide Depth
versus Density
Total depth 2200m
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Example of NO3-, NO2- and NH4 for R/V Knorr 2003
CIL
suboxic zone
Data suggests anammox
First seen during 1988 Expedition
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Results from Knorr 1988 Cruise (w/ Pump Profiling
System) Oxygenated surface layer over a sulfide
rich deep layer with a suboxic zone at the
interface
H2S
O2
Suboxic Zone
NO2
NO3
Murray et al (1995)
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Fe
Mn
NH4
PO4
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