chapter 22 Wiki Questions 4. Non-point sources are large or dispersed land areas that discharge pollutants into the environment over a large area while a point source is a single identifiable source that discharges pollutants into the environment. An example of a point source is a smokestack and an example of a non-point source is a crop field. Non-point sources are more difficult to deal with because it is hard to identify where specifically the pollution is coming from, therefore it is more difficult to target the source and stop it from discharging pollutants.5. Breaking down the wastes uses up a lot of the available dissolved oxygen, leaving organisms with a high demand for oxygen with very little of it. This can cause the population of these organisms to be depleted. 6. Cultural eutrophication is the overnourishment of aquatic ecosystems with plant nutrients (mostly nitrates and phosphates) because of human activities such as agriculture, urbanization, and discharges from industrial plants and sewage treatment plants. With this excess in plant nutrients comes an excess in plant growth called a “bloom” which blocks sunlight form reaching the water body and depletes oxygen on the surface layer and on the bottom layer (where oxygen is needed to decompose excess of dead organic material) which can cause fish kills. Three ways to prevent cultural eutrophication are to use waste treatment systems to remove nitrates and phosphates before wastewater is put into lakes, to limit use of household detergents and cleaning agents with phosphates, and use soil conservation and landuse control to reduce nutrient run-off. Three ways to clean up lakes suffering from cultural eutrophication are to mechanically remove the excess weeds, control undesirable plant growth with herbicides and algicides, and to pump air into lakes and reservoirs to avoid oxygen depletion. 7. Cleaning groundwater is difficult because it is expensive to pump it up and clean it then return it to the aquifer, a slightly less expensive solution is injecting microorganisms, another way this is still being developed is pumping in nano particles of organic material to remove the pollutants. The most effective approach is to not pollute it in the first place. This is done with monitors and leak detectors and banning hazardous waste disposal in wells. 8.The major forms of ocean pollution are industry and smokestacks releasing more chemicals to be dissolved into the ocean, cities and their sewage and farms with fertilizer runoff, construction causes excess sediments and decreased sunlight in the water. Red tides happen when excess nitrogen causes an algae explosion and and it poisons marine life. In the Chesapeake Bay pollutants from six states contaminated the estuary the waste was from point and nonpoint sources nitrate and phosphorous level increased causing oxygen deprivation and algae blooms. States worked together in an integrated coastal management and legislatures including city state and federal worked together to decrease the pollution inputs into the bay. They upgraded sewage treatment plants, reduced urban and agricultural runoff, and monitored discharge better. This worked well and phosphorus and nitrogen levels dropped, however, recently the funding has dropped and they Bay is no longer improving. 9.Humans produce algal blooms by fertilizer in agricultural runoff causing increased nitrogen and phosphorus causing increased algae growth which then causes less dissolved oxygen and more organisms to die. Sewage runoff can also contribute to this. They also release airborne toxins that damage fisheries, kill fish eating birds, reduce tourism, and poison seafood. 10. Agriculture can reduce non-point source pollution by preventing it from reaching bodies of surface water.Farmers can reduce soil erosion by keeping cropland covered with vegetation, they can reduce the amount of fertilizer used and using slow release fertilizers and not using fertlilizer on steeply sloped land, and planting buffer zones of cultivation inbetween cultivated fields. 11.The Clean Water Act and the Water Quality Act improved water quality by setting standards for allowed levels of key water pollutants. They required 15,500 livestock feedlots to purchase permits. They Develop plans to handle manure and wastewater. 12. Discharge trading policy; uses market forces to reduce water pollution. Under this program a water pollution source is allowed to pollute at a higher level than allowed in its permit by buying credits from permit holders with pollution levels below their allowed levels. 13. The Safe Drinking Water Act sets water standards called "maximum contaminant levels" for pollutants. Privately owned wells don't have to follow this. They suggest combining water treat systems that provide <3300 people with larger ones.