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.
What are anamolous lakes DO and temp patterns? Why? What are anamolous lakes mainly guided by?
See peak of oxygen at the top of the hypolimnion, this can be due to inflow of water- see big pocket, or odd shape of lake
What are the seasonal pattern of DOs in a dimictic oligotrophic lake?
In a typical dimictic lake (mixes fall and spring, and is low productivity (oligotrophic), in spring temp consistent throughout whole water column and oxygen also mixing throughout column
Summer stratification- have oxygen lower at surface and higher at bottom due to increased temp at top due to thermal stratification.
Fall turnover- same thing happens as spring
Winter stratification- have ice cover, see slightly colder at surface and slightly warmer lower down, therefore see slightly high oxygen at surface and slightly lower at bottom
What are the seasonal pattern of DOs in a dimictic eutrophic lake?
same in spring turnover, in summer, oxygen starts off highish but then goes off to 0 in hypolimnion, due to a lot of productivity- the hypolimnion has a lot of respiration and decomp.
During fall turnover is same, and then in winter stratification the oxygen start off high and then dips in hypolimnion, this is due to have organisms use up oxygen there, ice cover decreases photosynthesis, diffusion, and turbulence. Biological activity uses up oxygen.
What is fish winterkill?
This happens when there’s no oxygen due to ice cover, so fishes die and we see them at surface.
horizontal line indicates what in an oxygen curve?
stratification
What is summer kill?
When it gets really warm, don’t have oxygen near surface but increased productivity, however increased productivity gets oxygen used up in the bottom and fish die.
How do diurnal changes effect stream base don their initial productivity?
In oligotrophic system, the oxygen dips slightly during night and have more photosynthesis so more oxygen in day but very slightly, however in eutrophic system this change is much more.
If you have a bigger drainage basin do you have more nutrients?
yes
In slower rivers how does diurnal changes effect oxygen?
faster mover streams mean less macrophytes mean less changes.
Why is carbon important? (3)
Currency of energy transfer
Carbon is the chemical backbone of organic molecules
Proteins, hydrocarbons, lipids, carbohydrates
Carbon provides a buffering system for lakes to absorb excess acid
How does carbon effect global climate regulation?
Exchanges with the atmosphere
How does organic and inorganic carbon and dissolved and particulate carbon make ratios in water?
See mostly dissolved inorganic carbon, see then dissolved organic carbon, and then lastly see particulate organaic carbon
What is particulate organic carbon?
Living organisms
Dead organic
material
What is particulate inorganic material? (examples)
CaCO3 and other carbonates
What is inorganic dissolved materials?
CO2 , H2CO3 , HCO3-
, CO32
What is base of photosynthesis in terms of carbon?
inorganic carbon dissolved
Where does DIC come from?
comes from precipitation, inflow, and changes in atmosphere
Where does inorganic dissolved carbon come from?
comes from ppt, inflows, and exchnages from atmosphere
What determines the form of dissolved carbon from atmosphere in water?
the ph, go from CO2 (acidic) to carbonate (least acidic)
What is the bicarbonate equilibrium?
is the basis of the buffering system
What types of carbon are involved in DOC? POC?
humic and non humic
fine and coarse
What are humic compounds?
large molecular weight
compounds that lend a brownish color to water (impacts photosynthesis and heat in lake)
* By product of the breakdown of other organic
compounds
* resistant to microbial use
* humic acids, fluvic acids, humin
* can attach to other organic substances
* can form complexes with metal ion
- happens in anoxic ecosystems
What are non humic compounds?
are sugars, carbohydrates,
amino acids, urea, proteins, pigments, lipids
What is autochthonous?
comes from inside the aquatic system, carbon
synthetized through photosynthesis in the lake/stream
What is allochthonous?
comes from outside the aquatic system, carbon
synthetized in the drainage and imported in the lake/stream
What’s the difference between littoral and pelagic POC and benthic POC?
Is living organisms and detritius that gets sedimented.
Whats the old view versus new view of carbon in water?
that carbon came from land and into inland water and then into ocean, but new view is that some carbon goes back to atmosphere some gets sedimented, so less carbon enters ocean
