Transcript Frank
Chapter 14 Water Pollution Pollution Sources Water pollution is the contamination of water by substances produced by human activities and that negatively affect organisms Point source pollution comes from a distinct location that can easily be traced (factory, pipe) Nonpoint source pollution cannot easily be traced to the source (urban areas, farms). More difficult to control and more common Nutrient pollution Nutrient pollution comes from fertilizers, farms, sewage, lawns, golf courses, and leads to eutrophication Fertilizers add phosphorus to water, which boosts algal and aquatic plant growth Spreading algae cover the surface, decreasing sunlight Bacteria eat dead algae, reducing dissolved oxygen Fish and shellfish die Solutions include: Treating wastewater Reducing fertilizer application Using phosphate-free detergents/fertilizers Planting vegetation to increase nutrient uptake Human Wastewater Human wastewater is water produced by human activities (sewage, laundry water). High in nutrients. Leads to 3 concerns Oxygen demanding waste is organic matter that enters water and feeds the growth of microbes that are decomposers. 1. The more waste in the water, the more microbes. More microbes, the more they demand oxygen Biological oxygen demand (BOD) is the amount of oxygen microbes use when breaking down waste High BODs typically mean more wastewater. Eventually leads to dead zones because not enough oxygen to support life When organic matter is decomposed, nutrients are released 2. Eutrophication – nutrients added to water which brings algae blooms. These die and bacteria increases and uses up oxygen Cultural eutrophication is caused specifically by humans Continued… Wastewater can carry parasites and bacteria that can make humans ill. These are called pathogens 3. Cholera, typhoid fever, flu, diarrhea 3.1 million deaths per year caused by unsafe drinking water We only test for certain bacteria in our water since there are so many different kinds Treatment of Wastewater Septic systems are sewage treatment systems found in rural areas. Has two major components Sewage treatment plants are used for urban areas Septic tank takes wastewater in one end, and releases it out the other Leach field are pipes where the septage (clear layer full of bacteria) moves out. Septage slowly leaks out of pipes into the ground Primary treatment lets solid stuff settle and become sludge. From there it can be taken to landfill, farms, etc Secondary treatment uses bacteria to break down remaining organic matter. Also has a settling tank Water gets released to nature, but contains high N and Ph levels During times of heavy rain, treatment plants are overloaded and release raw sewage into nearby bodies of water A typical wastewater treatment facility Sludge = solid material resulting from treatment Is decomposed microbially Then landfilled, incinerated, or used as fertilizer on cropland Methane-rich gas created by decomposition can be burned to generate electricity Heavy Metals and Acid Deposition Lead enters water through old lead pipes. Can damage brain, kidneys, and nervous system (especially babies) Arsenic occurs naturally in rocks, but is increased by humans breaking up rocks. Leads to various cancers. Mercury is natural and is also increased by human activities. Most human related mercury comes from burning fossil fuels. Attacks central nervous system and fetuses. Often found in fish, mostly top consumers (bioaccumulation) Acid deposition comes from burning ff. Leads to death of trees and aquatic ecosystems. Coals scrubbers and static help Synthetic Organic compounds SOC are man-made organic compounds Pesticides help control pests, but lead to other problems Don’t only kill pest they are designed to kill Affect organisms down the food chain that eat these pests Cancer, birth defects, bioaccumulation Other common compounds found in water include military compounds, pharmaceutical drugs, and industrial compounds Oil Spills Toxic to many species, including algae which starts aquatic food webs Surface oil is sucked up, skimmed up, chemicals are applied that break it up, bacteria is applied that eats it up, or coagulate it No easy way to clean up underwater plumes Not All Pollutants are Chemicals Solid waste production Sediment pollution comes from small particles carried in rivers Occurs from land erosion (mostly in agricultural areas) Reduce sunlight, this reducing photosynthesis Clog gills Thermal pollution is when human activity causes water temp to change (power plants) Plastic rings strangle animals Medical waste hazardous to humans Coal ash, which contains heavy metals Dissolved oxygen decreases as temperature increases Noise pollution can affect animal communication (SONAR) Pathogens and waterborne diseases Enter water supplies through inadequately treated human waste and animal waste from feedlots Fecal coliform bacteria indicate fecal contamination They are not pathogenic organisms But the water may also hold other disease-causing pathogens (e.g., giardiasis, typhoid, hepatitis A) Bacterial pollution causes more human health problems than any other type of water pollution Dissolved Oxygen (DO) DO (measured in PPM) is necessary for aquatic life Most comes from atmosphere Rapidly moving water has higher DO levels Stagnant water with high levels of organic matter can contain oxygen consuming bacteria that leads to eutrophication As water temp increases, DO levels decrease, thus eutrophication is worse in summer Laws Clean water act (1972) Supports the protection and propagation of wildlife and recreation in and on the water Defined standards of acceptable limits of various pollutants Control how much discharge industries can put in water Safe drinking water act (1974, 1986, 1996) Established max contaminant level for 77 different elements or substances in surface and ground water Problem: In 2010, the South Anna River had a largemouth bass population of 25,000 individuals over a 10–mile stretch. In early 2011, a chemical spill occurred and the population of largemouth bass decreased to only 5000 individuals over the same area. Calculate the percent change in largemouth bass in the South Anna River. To calculate percent change: divide the difference between the beginning and ending quantity by the original beginning quantity. Then, multiply the answer (the quotient) by 100 to find the percent change.