Quiz 2 Lecture 3 Flashcards
What is dissolved oxygen?
Dissolved Oxygen (DO) refers to the O2
dissolved in water, expressed as mg/L or mol/L or percentage saturation
What is percentage saturation?
is concentration of O2 relative to maximum at equilibrium concentration
for that solution
DO is a function of what factors and how?
- Temperature - solubility of O decreases as T increases
- Pressure - solubility of O increases as P increases (related to altitude)
- Salinity - solubility of O decreases as S increases
What happens to DO as temperature increases?
The DO decreases
What is supersaturation?
DO concentration above
saturation. Will form O2 bubbles and come out of
solution
What is sub saturation?
Is DO concentration below saturation
What are oxic/aerobic conditions?
O2 present in the water
What are anoxic or anerobic conditions?
No O2 present in the
water
At high temp and high altitude what conc of O do we see?
the lowest DO
Do At low temp and low altitude?
see highest DO
What are the oxygen sources for water?
The atmosphere- amount depends on diffusion and turbulence (some of it)
Photosynthesis (most of it)
Why does oxygen from atmosphere source depend on diffusion and turbulence?
Because oxygen can get diffused at surface, alot of wind will bring turbulence and introduce oxygen in there
What are the oxygen sinks? (3)
Diffusion to atmosphere
Respiration
Chemical oxidation (happens in hypolimnion, cold bottom of lake, where no photosynthesis)
In an ocean what zone has the most photosynthesis oxygen production?
In photic zone where light penetrates and littoral zone
What are orthograde lakes DO and temp patterns? Why? What are orthograde lakes mainly guided by?
The oxygen doesn’t change much, is littler in epilimnion, gets slightly higher in hypolimnion. Because it’s warmer at the top, and the system is not that productive at the top. Mainly guided by temperature effecting solubuiloty of O
What are clinograde lakes DO and temp patterns? Why? What are clinogrades lakes mainly guided by?
Oxygen and temp high at surface, and then decrease lower down. This is because there’s high productivity at the top, they then die and sediment and respirate which causes more respiration and decreases DO at bottom. This is mainly driven by photosynthesis.
What are heterograde lakes DO and temp patterns? Why? What are heterograde lakes mainly guided by?
See big peak in oxygen at top of metalimnion and big dip at bottom of metalimnion. This is because at the top of the metalimnion there’s a lot of productivity, then have big organisms at the bottom of metalimnion that act as a sink for oxygen, organisms can’t move due to density and will trap zoo plankton in low metalimnion and plants at the top of metalimnion. Overall oxygen increases as temp decreases.