Lecture 7b Flashcards

(84 cards)

1
Q

What is the hydrological Cycle:

A

A biochemical cycle that involves the continuous movement of water on, above and below the surface of the Earth

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2
Q

What contributes to Mass Balance?

A

Precipitation vs. Evaporation

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3
Q

What Contributes to Lakes? (3)

A
  1. Atmosphere
  2. Lakes
  3. Groundwater
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4
Q

What does the Atmosphere Contribute to Lakes?

A
  • Gases: N2, CO2, O2
  • Nutrients: N, P
  • Precipitation
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5
Q

What does the Watershed Contribute to Lakes:

A
  • dissolved minerals from rivers
  • changing concentrations of solutes (when water flows over limestone (primarily CaCO3) will contain a high [ ] of Calcium (Ca 2+) and bicarbonate (HCO3 -)
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6
Q

What does the Groundwater Contribute to Lakes:

A
  • Nutrients: N, P
  • Toxins
  • CO2
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7
Q

Change in Chemistry Caused by Lake Age:

A
  • Certain ions decline with time due to biology and chemistry
  • Other chemical factors increase with time due to watershed
  • Some nutrients remain constant through time
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8
Q

Salts: Dissolved Solids - Consist of a Few Salts (11)

A
  1. Carbonates
  2. Sulfates
  3. Calcium
  4. Magnesium
  5. Sodium
  6. Potassium Chlorides
  7. Silicic acids
  8. Nitrates
  9. Phosphate compounds
  10. Iron
  11. Manganese compounds
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9
Q

Salts: Dissolved Solids - Consist of a Few Salts (Major) (7)

A
  1. Carbonates
  2. Sulfates
  3. Calcium
  4. Magnesium
  5. Sodium
  6. Potassium Chlorides
  7. Silicic Acid
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10
Q

Salts: Dissolved Solids - Consist of a Few Salts (Minor) (4)

A
  1. Nitrates
  2. Phosphate compounds
  3. Iron
  4. Manganese compounds
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11
Q

Salts: Total Dissolved Solids (TDS) - how they are done:

A
  • Evaporation (100 - 200 mg/L)
  • Endorheic Lakes (10^5 mg/L)
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12
Q

Salts: Inorganic Components:

A

Via loss on ignition (total = organic + inorganic)

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13
Q

Salts: Specific Conductivity (μS/cm)

A
  • Based on ion strength of the water
  • Conductivity = TDS x 0.65 (for normal waters)
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14
Q

Salts: Hardness

A

Sum of Ca + Mg (+Fe)

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15
Q

Salts: Temporary Hardness

A

= hardness + HCO3 + CO3
Loss when boiling + scale

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16
Q

Salts: Permanent Hardness

A

Hardness + SO4 + Cl + PO4

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17
Q

What are Endorheic Basins

A
  • Water drains into a basin without an outlet
  • When evaporation > precipitation, dissolved salt accumulate and precipitate
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18
Q

Gasses: Dissolved Gasses

A
  • O2, CO2, and N2
  • CO2 and N2 are important for processing through nutrient cycling
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19
Q

Gasses: Dissolved Inorganic Nitrogen (DIN)

A
  • Microbe dependent from N2 found in the atmosphere
  • N2 can be fixed by lightning or certain diazotrophs in soil and/or water
  • DIN = NO2 + NO3 + NH3 in water
  • Certain DIN is used by primary producers as N is needed for building proteins
  • Can be limiting under certain conditions, and co-limitation with P
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20
Q

Gasses: Dissolved Inorganic Carbon (DIC)

A
  • Is pH dependent and CaCO3 may be present in bedrock
  • CO2 + H2O <-> H2CO3 <-> HCO3 + H+ <-> CO3 + H+ + Ca <-> CaCO3
  • Certain DIC is used by primary producers; CO2 is respired by all organisms
  • Can be limiting under static and/or high pH conditions
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21
Q

Acidic Lake Water: CO2 between 4 - 6 pH (Componds)

A
  • High in H2CO3 and CO2
  • Low HCO3 -
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22
Q

Most Lake Water: CO2 between 6 - 9.5 pH (Componds)

A
  • High HCO3 -
  • Low H2CO3 and CO2
  • H2CO3 and CO2 become CO3 2-
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23
Q

Alkaline Lake Water: CO2 between 9.5 - 12 pH (Componds)

A
  • Low HCO3 -
    and loses HCO3 -
  • High CO3 2-
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24
Q

Process of Lake Whiting:

A
  • Following intense photosynthesis and
  • pH increases and CaCO3 precipitates
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25
Lake Water: Dissolved O2 (DO)
The single most important biologically relevant constituent of water that dictates biological activity and/or potential
26
O2 Saturation:
The amount of DO that can be held by water in equilibrium with the atmosphere at a particular 1. Temp, 2. Pressure, 3. Salinity
27
Subsaturated Waters
Are < DO saturation
28
Supersaturated Waters
Are > DO saturation
29
How Does O2 Diffuses:
high to low [ ] from the surface to the waters below and the rate is limited by the density and viscosity of water
30
What does O2 Diffusion Rate depend on (Other than [ ])
The rate is limited by the density and viscosity of water
31
How Can O2 Mix in Water
By turbulence and currents, and wind-driven spray can lead to supersaturation
32
What is O2 Introduction a Byproduct of?
Non-cycling photophosphorylation
33
What is Hypoxia?
deficiency in the amount of oxygen reaching the tissues
34
What is Anoxia?
An absence of oxygen
35
Lake Structure: Stratification (Isothermal Conditions)
Well mixed with circulation throughout the water column
36
Lake Structure: Stratification (Thermal Conditions)
- More buoyancy - Lack of Mixing (decreased inertia) - Both lead to density stratification
37
What is the Epilimnion Layer of Water in the Column?
- Is in contact with atmosphere and well mixed - Air-water
38
What is the Metalimnion Layer of Water in the Column?
- Is the Barrier between the epi and hypolimnion layers - Internal wave movement - Thermocline (HOD and SOD)
39
What is the Hypolimnion Layer of Water in the Column?
- Is isolated with compounds from isothermal + sediment + biology - Sediments
40
Components of Epilimnion:
- Warm - Low density - Surface waters - Well mixed energetic atmospheric contact
41
Components of Metalimnion:
- Zone of rapid tem change - Location of internal wave movement
42
Components of Hypolimnion:
- Cold - High-density - Deep waters - Isolated from atmos - Contact with sediments
43
Thermal and Chemical Seasonal Stratification (Winter):
- Surface Ice reduced O2 diffusion into surface waters - Potential for O2 from ice algae - Cold water creates increased O2
44
Thermal and Chemical Seasonal Stratification (Summer):
- O2 content set at the onset of stratification - Decline in O2 reflects uptake by decomposers inhibiting benthic zone (HOD and SOD)
45
What is HOD Stand for?
Hypolimnetic Oxygenation Demand
46
What is SOD Stand for?
Sediment Oxygen Demand
47
What does Hypolimnetic Oxygen Demand (HOD) do?
1. OM from the epilimnion (function (P load)) 2. Time since onset of stratification 3. Volume and hypolimnion 4. Temperature
48
What does Sediment Oxygen Demand (SOD) do?
1. Temp 2. Nutrient levels 3. DO in the overlying water 4. Velocity of the water
49
How Does Hypoxia Occur?
If HOD + SOD approaches DO in the hypolimnion
50
How does Anoxia Occur?
Occurs if HOD + SOD exceeds DO in the hypolimnion
51
Different Lake Trophic Statuses?
- Oligotrophic - Mesotrophic - Eutrophic
52
Oligotrophic Lake Status:
- Clear water - Low nutrient (especially P) input - Low SA:Vol - Low algal and macrophyte OM production and accumulation leads to cold hypolimnion with high DO below metalimnion
53
Mesotrophic Lake Status:
- Moderately clear water - Medium levels of nutrient input - Intermediate SA:Vol - moderate algal and macrophyte OM production and accumulation leads to cool hypolimnion with moderate DO
54
Eutrophic Lake Status:
- High [algal] - Receives high nutrients (N and P) - Low DO - Highest fish biomass (different species) - High algal OM production and accumulation leads to warm hypoxia
55
Dystrophic Lake Status:
- Receives excessive amount of OM - High algal production and accumulation leads to warm/hot hypolimnion with anoxia
56
What Happens When Algae Die and Sink to the Bottom:
Microbial action depletes the DO in the benthos (i.e., HOD and SOD) -> hypoxia and/or anoxia conditions that can be lethal to invertebrates and fish
57
DO Vertical Profiles (Oligotrophic)
- Clear waters - Often uniformly high DO below metalimnion
58
DO Vertical Profiles (Eutrophic)
- Turbid waters - DO decline below metalimnion due to HOD + SOD
59
DO Vertical Profiles (Mesotrophic)
- Peak DO at DCM (Deep Chlorophyll Maximum) in metalimnion - DO rich water trap during stratification + heating
60
DO Vertical Profiles (Mesotrophic)
- DO min due to HOD due to zooplankton + microbe decomp.
61
What is Silicate Limitation:
Weathering of continental lithosphere (granite) Becomes aluminosilicate clays comprised of Silica (SiO2)
62
Formula for Silicic Acid
SiO2 + H2O --> H4SiO4
63
Formula for Silicate:
H4SiO4 --> SO4 ^-4
64
Orthosilicate:
SO4 -4
65
Metasilicate:
SO4 -3
66
Pyrosilicate:
Si2O6 -7
67
How do Diatoms Use Silicate and Silicic Acid:
To form Biogenic Silica (SiO2) in their cell walls
68
What happens to Biogenic silica (SiO2) after Death?
Dissolves back to silicate although the process is controlled by: 1. Shrinking rate 2. Temp 3. Bacterial decomp of organism Otherwise, biogenic silica accumulates in sediments
69
What Does Anoxia Regenerate?
Phosphorous (P)
70
What is the Rain pH?
5.6 due to CO2 in air
71
What is the pH of Acid Rain?
4.2 - 4.4 by NO + SO
72
How is Acid Rain Neutralized (Buffered):
By ANC (Acid Neutralizing Capacity) in watershed soils
73
What does acid rain take out of soils?
Toxic metals like Aluminum (Al) from carbonate soils
74
What Does Acid Rain do to Macroinvertebrates and Vertebrates
Have high mortality and lower reproduction, but certain algae may thrive
75
What is the DOM and colour changing:
Dissolved Organic Matter can vary widely in color
76
What is CDOM and Colour changing:
Coloured Dissolved Organic Matter creates brown/yellowish hue to lakes
77
What Does DOC (Dissolved Organic Carbon) Affect?
- Biological - Physical - Chemical Processes
78
What Does Darker Water Absorbing more Heat Do (4):
- Strengthens stratification - Lowering mixing depths - Lowering primary producer productivity due to increased light attenuation - Increasing energy sources for the microbial loop
79
What Occurs With Chemical Transformations as Material Sinks:
- Lowers OM - Lowers Calcium (Ca) - Increases SiO2
80
Rate of Sedimentation is Related to What:
1. Watershed and lake productivity 2. Age of lake 3. Size of lake 4. Latitude and Climate 5. Solids and bedrock
81
Rate of Sedimentation (Age of lake... what it does)
Sediments accumulate over time
82
Rate of Sedimentation (Size of lake... What it does)
Larger fetch --> larger waves and shoreline erosion
83
Rate of Sedimentation (Latitude and Climate... What it does)
Longer growing season --> more organic
84
Rate of Sedimentation (Soils and Bedrock... What it does)
More erodible bedrock --> more sediments