2011 2: Water Pollution Flashcards
What is Down’s Issue Attention Cycle
the steps we go through when we hear about something: discovered by Anthony Down in 1972
what are the 5 stages
pre problem, alarmed discovery, realization of the cost, declining interest, post problem
pre problem
didn’t know there was a problem, or very few people knew
alarmed discovery
problem went public: alarmed discovery of big concern - people get interested
realization of the cost
have to do something due to all of the alarming news: figure out the problem, find a solution and see what it is going to cost (figuring out the impact!!)
declining interest
realize its too expensive or don’t know the exact solution, or its taking too long to figure something out : people lose interest/give up
post problem
problem is either solved or people gave up and don’t care anymore
Example of Walkerton
immediate solution: brought in bottled water, long term solution: filter the water
non persistent pollutants
domestic sewage, fertilizer, some industrial waste, bacteria, pathogens, viruses; can kill you very quickly
they will degrade on their own!!
degradable
the damage by these pollutants is reversible
o Can be broken down by chemical reactions or by natural bacteria into simple, non-polluting substances
o These will be broken down over time: sewage being thrown into a lake: only a few people putting it in = still safe! Once you get too much pollution, that’s when we should worry.
biological productivity
the amount of living material supported within a lake
least productive?
intermediate?
most productive?
least = oligotrophic
intermediate = mesotrophic
most productive = eutrophic
eutrophic?
means there is lots of life in the lake : we want a high biological productivity but we also want high biodiversity!
productivity can be determined by what?
temp, light, depth, volume, nutrients
pre-settlement: oligotrophic
o Before we arrived and settled the environment was mostly oligotrophic. When we arrived we changed the environment by cutting down trees and human activity adding nutrients wastes and industries causing the temperatures to rise and the increase the amount of nutrients in the system
currrent conditions?
temps of tributaries increased, amount of nutrients increase, sources
eutrophication?
(its like fertilizer for the lakes!)
increase in nutrients = growth of plants. Plants die, settle, and decompose; the life and decomposition uses the oxygen
biological oxygen demand (BOD)
depletion of oxygen via decomposition of organic material
- the more plants = less oxygen for other species like the fish
- too many nutrients = too many plants and all of the algae uses (decomposition)/blocks all of the oxygen causing other aquatic creatures to die
eutrophication and oxygen depletion: LAKE ERIE
- most vulnerable, first to go
- shallow, warm, most productive lake
- intense agricultural and urban development
- in the 1960s public concern grew = new pollution laws were put into place
What happened in 1972?
Canada and the USA signed the great lakes water quality agreement, they determined it was the phosphorous from industries and sewage treatment plants and worked with farmers to prevent nitrogen run off, stopped primary treatment plants - only secondary now!
1978?
zero discharge of contaminated stuff (drastically declined), not increasing from the last 30 years
so 1972 vs 1978
o Non-persistent (natural)….1972 (not good news) –easy (no more sewer leakage, not a lot agricultural pesticides) o Persistent (toxics)….1978 slowed the rate, not done, fish guidelines - hard
Pathogens
A specific causative agent of disease or a morbid condition
o Waterborne disease; bacterial, viral, and parasitic diseases
o This is why chlorine is added to drinking water (removes parasites)
o There is also a risk from direct body contact with it
o Walkerton- e.coli, people on reserves (dirty water)
Persistent Pollutants
once they’re out there we can’t remove them, they degrade SLOWLY or cannot be broken down at all, most rapidly growing type (within industries), remain in the environment for years or longer, damage is IRREVERSIBLE or reparable over DECADES, invisible so don’t know they are there, can be harmful in the smallest concentrations,
