Chapter 15

 Status of pollution  Threats to our environment  Relationships between air pollution, plants, & soils  Damage caused by sediment

 Problems are becoming worse  We’re getting more proactive/aware  Pollution – adding something to air, water, soil that makes it less desirable for human use of less able to maintain nature’s balance What are some examples of pollutants?

 Us Some of our actions, innovations, technology, industry inherently degrading to environment  Even though we didn’t know it at the time  Loss of Biodiversity Loss of species locally or globally 90% of world’s food produced on 30% of the land  Modifications of Landscapes & Climate Replacing nature’s way

 Drained wetlands  Man-made structures  Water withdrawals  Overexploitation Excessive fishing, lumbering, hunting, farming  Introduction of Nonnative species Noxious weeds Predatory animals/insect species  Pollution of Fresh Water Some rivers/lakes becoming less safe for drinking or recreation

 Soil degradation Threatens land Crusting, compaction, erosion, nutrient depletion, etc.

 Eutrophication – water overly enriched w/ nutrients forming algal bloom (robs O 2 from water)  Half-life – time for ½ of substance to be destroyed, inactivated  Total Maximum Daily Load (TMDL) – regulatory maximum amount of pollutants allowed in water – controversial – used by EPA  Don’t forget to check out the rest of the terms on pg 461

 Eutrophication of Surface Water Fertilizers increase algal growth in water Eutrophication accelerates algal growth & O2 tie-up N & P are the major culprits P pollution sources  Municipal sewage  Direct dumping of wastes  Eroded phosphate fertilizers

Dead Zone – eutrophic zone at end of Mississippi River – extensive aquatic death in 8000 mi 2 area  N in Groundwater N easily washed away ~½ of all N applied not used by crops  Not all N pollution from agriculture Maximize N usage by plants, minimize excessive N fertilization

 Methemoglobinemia Reduction in oxygenation of blood causing suffocation Cyanosis – “Blue Baby” syndrome in humans Related to high nitrate levels in drinking water Upper limit 45ppm in drinking water  Can be a problem w/ well water

 Wastewaters Added to Soils Sewage sludge, industrial wastes Many household chemicals found in wastewaters EPA restrictions tightening to protect waters  Sewage Sludge Has often been buried in landfills Can be land-applied & be just as helpful as animal manure Toxic metals, pathogenic organisms, human vectors (rats, mice, mosquitoes) can be problematic

 Livestock Manures Manure = #1 product of American agriculture  1.4b t produced annually Trend toward fewer, larger animal production units causing more concentration of manure  What are our options? Manure nutrient content varies w/ rations  Concentrated in some undesirable nutrients (salts)

 Municipal Garbage, Composts, Sanitary Landfills Recycling has improved Toxic cleaners, pesticides, medicines, solvents, etc. are the major problem/risk Increased tonnage & tighter regulations making more problems  Food-processing Wastes Pea pods, tomatoes, peanuts, etc. Organic (except for any chemicals used in processing) & can be composted Wash water can also pollute, should be treated

 DDT Developed in 1880’s Kills almost all insects easily & quickly  Mosquitoes Low toxicity to humans, animals Inexpensive & long lasting Two major drawbacks:  Long ½ life (10-25 yrs)  Accumulates in animal fats – birds eat dead insects, kills birds U.S. banned in early 1970’s

 Pesticides Today Many hundreds of pesticides available Acceptable pesticides must have following characteristics:  Short-lived in environment  w/in 1-2 wks, or 1-2 d  Not carcinogenic, teratogenic, mutagenic  Effective & practical to use  Not volatile  Safe to apply w/ reasonable care  Stay where applied

 Pesticide Problems & the Extent of Pollution Toxicity to humans & animals major concern Some argument as to safe/acceptable levels Resistance becoming a problem  To what?  How?  What are our options? Ag accounts for 2/3 of all pesticide use in U.S.  Atrazine most applied herbicide  High risk for pollution due to being sprayed on bare soils, early spring, more rain

 Very immobile in soils, tightly held  Can result from many sources Sludges, fertilizers, atmosphere (ore smelting), paint waste, etc.  Some sources now closed, tightly regulated, installed more environmentally friendly equipment

 Toxic plants to animals (can be in certain soils) Weeds, nutritive elements Those using pasture in their animal production units must have idea of risk, be able to identify symptoms

 Lead Contamination Some say most important environmental hazard world-wide Atmospheric lead sources – burnt fuel in autos  Decreased now w/ lead-free gas  Soil Pb levels still high near roads Can cause brain damage  Field Burning Traditionally used to control weeds, insects Risk from smoke  Reduced visibility – auto accidents  Air quality issues

 Acidic Rain & Fog Acid rain – rain w/ pH <5.6  Most severe near heavy industrial areas  Sulfuric acid & nitric acid Acid fog – acidity more concentrated – pH 2-3  Can cause serious injury to plants EPA regulations have improved this problem  Acid rain emissions down 62% from 1970’s

 Ozone Depletion & Enrichment Ozone – screens 99% of UV rays from Earth Chlorofluorocarbons (CFC’s)  Where do they come from?  Have been banned? Ozone declined steadily until mid 90’s, now evidence of recovery  Greenhouse Gases Components that trap heat near Earth’s surface CO 2, nitrous oxide, methane, etc.

Abundance of these gases causing “Global Warming”  Many disputes  Some historical data used is projected or estimated  See figure on pg 478  Evidence of ice melting  Evidence of animal migration away from warmer areas  Some arguing this is in preparation for another mini “Ice Age”

 Sediment Problems Both physical & chemical problem  Filling in of waters  Pollutants carried w/ it Sources/causes:  Eroded topsoil  High in nutrients  Filling of water reservoirs  Reduced sunlight penetration into water  Lower amounts of food produced for aquatic organisms

 Covering of good topsoil w/ poorer sediment  Raising of river beds – more prone to flooding

 Global Warming Discussion