The Breaking Point: Cuyahoga RiverCleveland, Ohio
Clean Water Act (1972)• Addresses point-source pollution.• Set benchmarks, deadlines, and penalties fornon-compliance.• Not perfect but is at least an attempt toaddress the problem.– We are FARbetter off today.
Agricultural Pollutants• The latest EPA National Water QualityInventory indicates that agriculture is theleading contributor to water qualityimpairments, accounting for 60 percent ofcontamination in rivers and lakes.• Why?– Most agricultural pollution is considered non-point source and therefore not subject to theClean Water Act.– The way agriculture is practiced has changedgreatly in the last 50 years.• Rise of Factory Farming.
Changing Market Conditions• In the 1970s the top 5 meat packing companiesprocessed about 25% of the market.– Today the Top 4 (Tyson, Cargill, Swift, and NationalBeef) process more than 80% of the meat we eat.• In the 1970s, there were thousands ofindependent slaughterhouses nationwideproducing the majority of beef sold.– Today, we have only 13.• Vertical Integration: When a company assumescontrol of multiple stages in the productionprocess.
What to Do With the Poo?• On a small diversified farm manure isused as fertilizer for crops.– Small enough amounts of manure that itcan be broken down naturally to providethe plants with nutrients.• Large-scale commercial livestock andpoultry operations produce an estimated500 million tons of manure each year.– More than three times the sewageproduced by the entire U.S. humanpopulation.– Funneled into waste lagoons which oftenleak.• Becomes highly concentrated.– 75 X More Concentrated than raw humansewage.• Then sprayed on fields at levels far byondwhat can be absorbed.– Runoff!
NUTRIENT POLLUTIONHow you can have too much of a good thing…
Quick Review: Elements vs. Compounds• Elements: Smallest division of matter. Youcan’t break matter down into any smallerchemically different pieces.– All material on earth is made up of 92 naturallyoccurring elements.• Compounds: Two or more different elementsbond together to form compounds.– These compounds often have very differentchemical and physical properties than theircomponent elements.
Nitrogen• When it comes to nutrientpollution the element weare most concerned withis Nitrogen.• Elemental nitrogen is acolorless, odorless, tasteless, and mostly inert (non-reactive) gas.• Makes up 78.09% ofEarth’s atmosphere.
Nitrogen• Nitrogen itself is a fairlyabundant element hereon earth.• However, the vastmajority of thatnitrogen is in the formof N2 an inert gas.• N2 gas cannot be usedby plants directly.
Nitrogen Compounds• Plants can only make use ofNitrogen when it is inchemical compounds such asNH3 (Ammonia) and NO3(Nitrate).• These compounds are fairlyrare in nature.• For this reason Nitrogen isoften a limiting nutrient inecosystems.– Gets used up quickly (andreplenished slowly).– When you run out plants stopgrowing.
Nitrogen and TraditionalAgriculture• The issue of nutrient (Nitrogen) depletionhas plagued Agriculture for centuries.– There is a limited amount of useable Nitrogenin the soil and it replenishes slowly.– Each planting season removes Nitrogen fromthe soil and it is carried away with the crop.• For many years farmers dealt with thisproblem in 3 main ways.– Move: Find new nutrient rich land to farm.– Fertilize: Spread animal waste (manure) thatis high in Nitrogen.– Crop Rotation: Alternate between planting acrop that uses lots of nutrients, like corn, andlegumes (soy beans) that replenish nitrogen.• Soy Beans have sacs of Nitrogen fixing bacteriathat convert atmospheric nitrogen into useablecompounds.
The Birth of Nitrogen Fertilizers• During WW2 German chemistsFritz Haber and Carl Bosch, inan attempt to makeexplosives, developed aprocess to synthetically createNitrates and Ammonia.• This technology revolutionizedhow agriculture was practiced -these synthetic nitrogencompounds could be used asfertilizer.• “The Green Revolution”
Too Much Nitrogen• With the availability of cheapNitrogen fertilizers many farmersswitched over.– These are often over-applied in anattempt to generate the highestpossible yield.– Also creates an issue of excess manure.• It is estimated that nitrogen fertilizers(both artificial and manure) aregrossly over-applied.– Only 30-50 Percent of the Nitrogenfertilizer applied by US farmers is usedby the target crop plants.– The rest enters the environment asnutrient pollution.– More is not necessarily better! Usefertilizer more efficiently.
Eutrophication• Remember: In most aquatic systems Nitrogenacts as a Limiting Nutrient.– The ecosystem can only support a certain numberof plant (algae) species.– You can only have as many plants as there isnitrogen to support them.• When nitrogen-rich runoff from factory-scalelivestock operations and farm fields enters abody of water it greatly alters the nutrientbalance.– Greatly increases the amount of nitrogen.
Eutrophication• Eutrophication:Process in which abody of waterreceives excessnutrients stimulatingexcessive plantgrowth.– Nitrogen is no longerthe limiting nutrient.– Algae Blooms.
Think back to Biology?• What is photosynthesis?– Occurs in plants.– Converts Sunlight (energy), Carbon Dioxide, andNutrients into Complex Organic Molecules andOxygen.• What is cellular respiration?– Occurs in animals.– Breaks down Complex Organic Molecules andOxygen into Energy and Carbon Dioxide
Hypoxia• Eutrophication produces lots of organic material.When this material decomposes it uses upOxygen and produces Carbon Dioxide.• Hypoxia: Water that has very low, or no dissolvedoxygen.– Incapable of supporting life.– Result of decaying organic material.– Generally happens in deep water, at night, or duringdroughts.• Causes fish kills and can lead to dead zones.– Dead zone in Gulf of Mexico is 8,500 square miles.
Deadzones• Deadzone in Gulf ofMexico is 8,500 squaremiles.• Hypoxic Zones occurworldwide.• Map• Major threat to thefishing industry.