Nutrients, their cycling, and upwelling

1
Nutrients, their cycling, and upwelling

• Nitrogen cycling
• Living is easy when there is upwelling
• But when the going gets tough cycle!
• Silica is THE upwelling nutrient
• Has a deep ocean cycle

2
Biolimiting constituents (a.k.a. nutrients)
Nitrate (NO3-) Does not limit growth of
bluegreen algae
(cyanobacteria) they fix nitrogen.
Silicate (H2SiO4) Limits the growth of diatoms
Phosphate (HPO4) the ultimate limiting nutrient
for plant growth
3
Vertical distribution of nutrients
nitrate 10-6 mol/liter
Phosphate 10-6 mol/liter
silicate 10-6 mol/liter
Libes, 1992
nutrients become fully depleted during
stratification
4
Hydrocast gear
Niskin bottle rosette with 36 bottles for
collecting sub-surface water
5
The physics of the annual cycle sets up the
biology.
6
The annual Stratification sequence causes a
limitation in nutrients.
http//www.bigelow.org/shipmates/overview.html
7
Productivity follows the nutrient availability
8
Cycling of nitrogen in the ocean
Uptake and use is the dominant part.
9
The Marine nitrogen cycle
10
The simple Nitrogen cycle
0
-III
III
V
-III
11
Different oxidation states of nitrogen
Libes, 1992
12
The Nitrogen cycle- reality
13
Annual Stratification sequence
Recycling of nutrients at its peak and
nutrients at a minimum productivity slows down,
respiration picks up.
14
The Nitrogen cycle when nutrients are low the
saviors come along
0
Energy intensive
-III
III
V
-III
15
New versus regenerated production
Lalli and Parsons
Note the biggest arrow is upwelled NO3
16
The Nitrogen cycle when things get tough
You see the other half of the cycle
The saviors
The spoilers
Energy intensive
Anaerobic
17
Low oxygen and the spoilers
?CO2
18
The Nitrogen cycle the spoilers
Lost to the system
0
Anaerobic respiration
-III
III
V
-III
19
Aerobic versus anaerobic
20
The Nitrogen cycle the whole story
Lost to the system
Input to the system
0
Anaerobic respiration
Energy intensive
-III
Input to the system
III
V
-III
21
Silica the upwelling nutrient
Silicate (H2SiO4) Limits the growth of
diatoms SiO2 (Silica) is an important nutrient
only for diatoms Silica is a mineral and only
resupplied from deep water.
22
Vertical distribution of nutrients
nitrate 10-6 mol/liter
Phosphate 10-6 mol/liter
silicate 10-6 mol/liter
Libes, 1992
In upwelling zones/during upwelling phosphorous
and nitrate are generally not fully depleted
23
The biological pump.
Not only controls carbon but the nutrients
including silica
24
Horizontal distribution of Silicate
We see a dramatic difference in distribution
between the Atlantic and the Pacific
25
The conveyor belt circulation
And thermohaline circulation moves CO2 through
the system
26
Silica the upwelling nutrient
Silicate (H2SiO4) Limits the growth of
diatoms SiO2 (Silica) is an important nutrient
only for diatoms Upwelling zones are areas with
high diatom productivity because silica is
plentiful This is because silica from deep water
is upwelled there.
27
Siliceous plankton make siliceous oozes
Diatoms
silicoflagellates
Shells are composed of silicon (Si)-
(glass) Form silica deposits on ocean floor
(siliceous ooze)
radiolaria
28
The silica cycle
Silica is undersaturated and dissolves it only
forms deposits under major productivity areas
29
Open ocean zones of upwelling .
Mann and Lazire
30
Silica cycling in an upwelling zone
31
Coastal Upwelling zones in the world ocean
Mann and Lazire
32
Silica cycling in a coastal upwelling zone
33
Distribution of siliceous sediments
Distribution of siliceous sediments largely
aligns with upwelling zones
34
How do we trace the movement of components in the
ocean?

• We start off with nutrients because they are
  trace-ablethey control productivity.

35
(No Transcript)