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?
How does it get there?
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Our island is a bit different:
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Aquifers:
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Huge aquifer-note recharge time is in centuries, pesticides in Nebraska, cancer rates there are very high...
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Water diversion (e.g. rivers)
Look up Three Gorges Dam in China
Two critical issues for China:
Pearl river delta and salt intrusion (sea level rise)
Vanishing Himalayan Glaciers (no farming in western China):
Glaciers are the water towers for Asia...
Rivers impacted:
Ganges, Yangtze, Yellow, Mekong, Brahmaputra, Irrawaddy, Indu, Salween,
Aral Sea (asia minor)
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Water disputes:
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Section two: Pollution
Big ideas:
1. Rivers are continuous, so easier to find sources along the route (continuity analysis: all sources add to total)
2. 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)
3. 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.
Water Pollution categories:
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Pollutant list:
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Nitrate levels (note farming regions):
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:
Three 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
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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