Pollution week! Announcements. What caused the dust bowl? Dust bowl:

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1 Announcements Exam grades will be posted by tomorrow Last weekend for L.E.A.D. Mar 12 th. You must submit your summary by Mar 14 th Extra credit movies due next Tuesday Pollution week! Today: Water conservation and pollution Hydrological cycle Water exploitation Water pollution Dust bowl: What caused the dust bowl? Settlement during unusually wet period Farming with excessive tilling and without crop rotation Several years of drought Solution: Ogallala Aquifer (World s largest aquifer, tapped extensively after WWII) South Dakota Oklahoma 1

2 Readings Hogan 2014 Learn about sources of water pollutants Postel et al Get a sense for how a global water budget is constructed Pools of water Volume (km 3 ) % Atmosphere 13, Fresh water 2,500, Groundwater 8,200, Ice 27,000, Oceans 1,350,000, Sum 1,380,000, Water sources Estimates from Postel et al. Science 1996 Evaporation & transpiration (evapotranspiration) Condensation & precipitation Purification Transportation Hydrologic Cycle Human impacts on hydrologic cycle Overdrawing water supplies from reservoirs and groundwater (land subsidence, saltwater intrusion) Deforestation, over cultivation, overgrazing, and paving: increases flooding, decreases groundwater supply Water pollution: harms wildlife, makes water unusable 2

3 Human-logic cycle Purify water - municipal treatment plants Use water (consume, pollute) Purify water again waste-water treatment plants Mississippi River water passes through people 7x before it enters Gulf of Mexico Municipal water use and treatment. Mr. Floatie s mayoral campaign, Victoria, BC (P.O.O.P. party) WWTP: - Primary - Secondary - Tertiary Wastewater treatment: 1: Remove solids (sludge) 2: Break down dissolved organic material (bacteria) 3: Remove nutrients and chlorinate effluent 4: Release Water exploitation Water exploitation Ogallala aquifer Withdrawal = 5-30 x recharge rate Lowering ~6 ft per y Estimated life at current rates ~25 y What will happen in 25 y? Why is the water overused? Should Fed gov t subsidize water use by agriculture (e.g., cotton) or water conservation? 80% of consumptive use in U.S. is for agriculture How can the US stop overuse? Figure: Water-level change: Predevelopment to 2005 (Source: USGS 2007) 3

4 Australia Water markets Price and use of water varies with availability (More water in 2009 than 2007) Water entitlements versus allocation. Allocations are tradeable. Water markets have improved efficiency of water use and allocation. Water markets in US No Federal markets States make their own rules Rule of Capture: You can pump water below your own land (with exceptions) Texas is the only state with a water market The Texas Water Exchange (Started in 2014 for groundwater only) Water exploitation elsewhere India: Withdrawal = 2x recharge rate China: Water table dropping 5 ft per y Ganges, Yellow and Nile Rivers barely reach the ocean Sprinklers Water conservation drip systems 50% U.S. systems gravity flow Percolation loss at low spot in furrow First three photos from: 4

5 Water conservation at home Tips for conserving Don t water a lawn New toilets Short showers New clothes washer Use a dishwasher Stop leaks Water pollution Solid Waste (plastics, cigarette butts) Organic contaminants BOD: Biochemical Oxygen Demand 46,000/mi PAH: Polycyclic Aromatic Hydrocarbons 2 Halogenated Hydrocarbons (adding Cl, F, Br) Heavy metals (Pb, Cr, Cu, etc.) Organo-metals: Methyl-Hg (Neurotoxin), TBT (immunity) Pathogens (bacteria, viruses) Water property changes (e.g., temperature) Excess nutrients Water pollution sources Half pound of plastics found inside dead albatross Image from US Coast Guard Deepwater Horizon: April 21, million barrels of oil leaked into GOM Photo from National Geographic 5

6 Water pollution sources Sources of pollution in Puget Sound (EPA 2007) Primary sources Runoff & discharges atmospheric deposition Point sources Nonpoint sources From Garrison (2002) Oceanography Behavior of organic contaminants in water More polar (charged) compounds remain dissolved in water Smaller volatile compounds move toward the atmosphere Biologically active molecules accumulate in the food chain Water Air Fate of DDT Water Living things 6

7 Biomagnification Puget Sound contaminants N S N S Organic contaminants in harbor seals from Ross et al. (2013) Puget Sound contaminants Water pollution effects Nutrients and eutrophication Nutrients limit productivity Key limiting nutrients: nitrogen and phosphorus Excess nutrients act as pollutants Steps: Increased N or P Increased phytoplankton productivity Decreased water clarity Mixing rates low: - phytoplankton sink to bottom - respiration consumes oxygen - aerobic organisms emigrate or die Organic contaminants in harbor seals from Ross et al. (2013) 7

8 Pollution and population size Hypoxia in Hood Canal N input to coastal zone correlated with population size Plot from Howarth et al. (2000) Hypoxia and stratification in Hood Canal July 31, 2004 outflow inflow Average circulation time: 1 to 5 months Stratification is greatest in summer and fall Dissolved oxygen in July Data from Warner (unpublished) Photos from 8

9 Global distribution of dead zones Lake Whatcom WWU s Institute of Watershed Studies monitors Lake Whatcom water quality Lake Whatcom issues: Declining dissolved oxygen in bottom water Increased growth of cyanobacteria Increased concentrations of trihalomethanes Number of dead zones has doubled each decade since the 1960s From Diaz and Rosenberg, Science 2008 Reducing water pollution Reducing water pollution Clean Water Act (1972) Use alternatives to pesticides and control erosion Pick up after your pet Dispose of oil and household chemicals properly Disposal of Toxics Facility 3505 Airport Drive Bellingham