Energy->Water->Food->Culture
(Also Chapter 12 in Froggie book)
Water: key points
Section one: What is it, where is it:
Freshwater, saltwater, how it moves, aquifers and reservoirs, impact of climate change, water wars
Section two: Pollution:
Often human driven (anthropogenic): Nutrient, thermal, BOD, sediment
Almost always human driven: Pathogens, inorganic chemicals, organic chemicals, radioactive chemicals
Section three: Water Quality index:
DO, BOD, pH, temp, turbidity, conductivity, nitrates (NO3), phosphates (PO4)
Section one: What is it, where is it?
Where is the water? Note: 97% salt water
How does it get there?
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Our volcanic island is a bit different: A shield volcano
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Water "boxes" on our planet (your planet may vary):
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Aquifers: open or closed ("captive")
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Huge Ogallala aquifer-note recharge time is in centuries, pesticides in Nebraska, cancer rates there are very high...
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Water diversion schemes, usually rivers:
Two emerging critical issues for China due to climate crisis:
- Pearl river delta and salt intrusion (sea level rise): gradual slope, so 1 meter of sea-level rise is many km of salt intrusion, so no more rice farming in that area
- Vanishing Himalayan Glaciers: no farming in western China, no annual flow through their two main rivers
Glaciers are the "water towers" for all of Asia...
Rivers impacted:
Ganges, Yangtze, Yellow, Mekong, Brahmaputra, Irrawaddy, Indu, Salween,
Another example: Aral Sea (asia minor)
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Notable Water disputes: Energy wars, water wars, then food wars...
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Section two: Water Pollution
Big ideas:
- Rivers are continuous, so easier to find sources along the route (continuity analysis: all sources add to total)
- Groundwater is harder to determine point sources, as flow is over larger area (not confined by river banks) and there is no continuity analysis possible (we don't know sources and sinks)
- Oceans are the hardest to trace, and impact everyone eventually, just like the atmosphere, only without the rain, and it is wetter. And full of fish.
Major Water Pollution categories:
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Water Pollutant list: Common culprits
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Industrial farming: note nitrate levels:
Why is there a hypoxic zone there?
Biochemical Oxygen Demand (BOD):
Better diagram:
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Note that temperature changes DO (dissolved oxygen) content, so does physical agitation (aeration).
Section three: Water Quality Index:
http://www.water-research.net/index.php/water-treatment/water-monitoring/monitoring-the-quality-of-surfacewaters
http://www.water-research.net/watrqualindex/index.htm
Calculation worksheet:
Main case studies-each related to a form of human pollution:
Case 1: High turbidity
Causes: erosion of topsoils, till farming, no cover crops, e.g. dustbowl in the US
Impact: poor light transmission, so low photosynthesis, low DO
Case 2: Low Dissolved Oxygen (DO)
Causes: Thermal pollution, e.g. power plants on rivers
Case 3: Eutrophication (high N and/or P)
Causes: Fertilizers, animal waste, e.g. Mississippi dead zone, Chesapeake bay
Chesapeake bay is the perfect storm of these three:
1. Warm water: shallow, so no cool lower zone away from sunlight, dissolved solids turn visible light into heat
2. High Turbidity: watershed runoff from rivers to the Appalachian range and north to NY state
3. Eutrophication: chicken and pig farms, runoff from farms along watershed
See also point source and non-point source pollution (from Poisoned Waters video, remember the Deer?)
Important: cooler water holds dissolved oxygen better (fishermen know this, so do the fish).
Water Quality Lab:
Tests: Probe sets
- Turbidity sensor: passes light through a small vial, measures light that passes, low light=high turbidity
- Conductivity: passes electric current through sample, proportional to salt content
- Temperature: warmer water has lower DO
- Dissolved Oxygen: amount of oxygen dissolved in the sample
- pH: acid/base tendency
Tests: dip strips:
- Alkalinity
- pH
- Hardness (calcium/mineral content)
- Iron
- Copper
- Lead
- Nitrate
- Nitrite
- Chlorine
Lab samples
- Post waterfall
- Post power plant
- Everglades close to ocean
- Post sewage plant
- Best fishing spot
- Mine tailings runoff
- Snow melt river
- Mississippi river
- Chesapeake river
- Flood after monsoon rains
- Golf course runoff
- Eutrophied lake
Metrics:
- DO
- BOD
- pH
- temperature
- turbidity
- conductivity
- nitrates
- phosphates
Simulated locations:
Samples:
Sample A
- DO:1.5
- BOD:low
- pH:7
- temperature:30°C
- turbidity:high
- conductivity:low
- nitrates:high
- phosphates:high
Sample B
- DO:6
- BOD:low
- pH:7
- temperature:10°C
- turbidity-low
- conductivity-low
- nitrates-low
- phosphates-low
Sample C
- DO: 4
- BOD:low
- pH:8
- temperature:25°C
- turbidity: high
- conductivity: high
- nitrates: high
- phosphates: high
Sample D-
- DO: 2
- BOD: high
- pH:5
- temperature: 28°C
- turbidity:high
- conductivity: low
- nitrates: low
- phosphates: high
Sample E
- DO: 2
- BOD:low
- pH:2
- temperature:20°C
- turbidity:high
- conductivity: high
- nitrates: low
- phosphates: low
Sample F
- DO: 1
- BOD: high
- pH: 4
- temperature: 30°C
- turbidity: high
- conductivity: high
- nitrates: high
- phosphates: high
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