Lecture 6

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Lecture 6

Shape of the oceans


Horizontal Structure


Vertical Structure


WOCE CFC-11 Inventories for N. Atlantic Water Masses

Labrador Sea Water

Overflow Waters


Atmosphere

Production

1.00

is the Atm. 14/12 Ratio by Definition

Surface

0.95

Variable

Deep

0.87

Overturning

Mixing/

Exchange

The 14 C half-life is 5700 years, so a 10‰

drop is ~80 years and the 0.87 value for

the deep ocean is ~1100 years.


SUN

THE GREAT BIOGEOCHEMICAL LOOP

TWO BOX MODEL OF OCEAN

C s

SURFACE

LIGHT

biological export

π

ν

physical transport

& mixing

0m

C d

Dissolved CO 2

and Nutrients

PHYTOPLANKTON

Organic Matter

and Oxygen

00m

TRANSPORT

Dissolved CO 2

and Nutrients

SURFACE OCEAN

DEEP OCEAN

BACTERIA

+

ZOOPLANKTON

SETTLING

AND TRANSPORT

Organic Matter

and Oxygen

DEEP

But not all 1° production

falls out of surface layer.

In fact there is a large

amount of “recycling”.


Flux=F 100

(z/100) -0.858

F 100

=1.53 mol/m 2 /yr

PP=22.2 g/m 2 /yr

Martin et al. (1987)


Redfield,

Ketchum and

Richards


How to Make a Phytoplankton:

106CO 2

+ 16HNO 3

+ PO 4

+ 122H 2

O CH 2

O) 106

(NH 3

) 16

(PO 4

) + 138O 2

In the North Atlantic this reaction consumes all available nutrients,

not so in the Southern Ocean. There is a larger value of “Preformed”

Phosphate in AABW than in NADW.

Also, this reaction only draws down about 10% of the Dissolved

Inorganic Carbon (DIC) in surface waters

One of the oldest questions in Oceanography is what limits primary

production, Nitrate or Phosphate (or light, or Fe or Zn).

On the other hand, the remineralization of organic matter in the

deep ocean will release a large amount of N and P back to the

dissolved phase.


Arabian Sea


Open Ocean

Coastal


Gruber and Sarmiento, 1997


Advection of Negative N* Around the Ocean


High Nutrient-Low Chlorophyll (HNLC) Regions of the

Ocean

Dust from the Galapagos Islands is fertilizing new phytoplankton growth down

wind of the land mass...


Martin and Fitzwater, 1988


Fe Profiles

Open Ocean


Boyd et al., 2000


So, what are a few of the outstanding questions in the field:

-Why is deep DOC so old?

-How do you get “new” Nitrate into the euphotic zone?

-How much fossil fuel CO 2

can the ocean adsorb?

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