Transcript Slide 1
Chapter 14
Water Pollution
The Chesapeake Bay
• • • Chesapeake Bay – largest estuary in the US Pollutants: – Excess nitrogen and phosphorus • From 3 major sources: • Consequence of increased nutrients – Sediment increase • Causes: – Anthropogenic chemicals, including: • Pesticides • Pharmaceutical drugs Trying to clean the CB – massive size = monumental effort – – 2000 2010
Water Pollution
• • • Water pollution- the contamination of streams, rivers, lakes, oceans, or groundwater with substances produced through human activities and that negatively affect organisms.
Point sources- distinct locations that pump waste into a waterway – Ex : Nonpoint sources- diffuse areas that pollutes a waterway – Ex:
Types of Pollutants
• • • • • • Human wastewater Inorganic substances (ie. heavy metals) Organic compounds Synthetic organic compounds Oil Nonchemical pollutants
Human Wastewater
• • Water produced by human activities such as: Can be difficult to prevent human wastewater from contaminating human drinking water bc …
Three reasons scientists are concerned about human wastewater:
• • • Oxygen-demanding wastes are broken down by bacteria that put a large demand for oxygen in the water Nutrients that are released from wastewater decomposition can make the water more fertile causing eutrophication Wastewater can carry a wide variety of disease-causing organisms
Oxygen Demand
• • • Oxygen demanding waste – organic matter that enters a body of water and feeds the growth of bacteria (decomposers) BOD (biological oxygen demand)- the amount of oxygen a quantity of water uses over a period of time at a specific temperature Dead zones – areas where this is so little oxygen, there is so little life
Nutrient Release
• • Nutrients (ie phosphorus, nitrogen) present from human wastewater Eutrophication – increase in fertility of a body of water – Cultural eutrophication – due to anthropogenic inputs of nutrients • Ex: Dead Zone in the Gulf of Mexico
Why is eutrophication a bad thing?
Sewage
↑ Enrichment Explosion in algal, bacteria & decomposer populations Fish kills ↓ Oxygen levels in water ↑ Biological oxygen demand (BOD)
Disease-causing Organisms
• • • Pathogens – illness-causing viruses, bacteria and parasites – Illnesses include: Indicator species – organism that indicates whether or not disease-causing pathogens are likely to be present Fecal coliform bacteria – group of generally harmless microorganisms that live in the intestines of humans and other animals
Treatments for Human and Animal Wastewater
• • • Septic systems- a large container that receives wastewater from the house – Consists of a septic tank and leach field • Septic tank • Leach field Environmental advantages to septic system: Downside:
Treatments for Human and Animal Wastewater
• • Sewage Treatment Plants- centralized plants in areas with large populations that receive wastewater via a network of underground pipes – Primary treatment – Secondary treatment Problems – high amounts of nitrogen and phosphorus can cause eutrophication
What is removed…
Treatments for Human and Animal Wastewater
• Manure lagoons- large, human-made ponds line with rubber to prevent the manure from leaking into the groundwater Risks:
Heavy Metals and Other Substances
• • • • • Lead Arsenic Mercury Acids Synthetic compounds – Pesticides – Pharmaceuticals – Hormones
Lead
• • • • Heavy metal Rarely found in natural sources of drinking water – Sources: Most at risk – fetuses and infants – Risks: In mid-1990’s- 10% + municipal water supplies contained lead levels that exceeded max permitted by Safe Drinking Water Act
Arsenic
• • • • Occurs naturally in Earth’s crust, can dissolve into groundwater – Human activities (ie mining) can increase Can be removed via: Problems associated with: Many people suffer from arsenic poisoning with no other options
Mercury
• • • Image – mercury releases from different regions of world Comes from: Inorganic mercury (Hg) not dangerous – Bacteria (in wetlands and lakes) convert Hg into methylmercury – Methylmercury is highly dangerous to humans • Most at risk – developing embryos and young children • Can cause:
• •
Acid Deposition and Acid Mine Drainage
Acid deposition – acids deposited on Earth, reducing the pH of bodies of water to below 5 – Wet deposition vs. Dry deposition – What’s being done to prevent?
Acid mine drainage – resulting from underground mines that fill with water once abandoned – Lower pH = harmful metal ions become water soluble – What can be done?
– Problem
Synthetic Organic Compounds
• • Synthetic – human made Includes: – Pesticides – can be detrimental to the environment • Concerns : – Pharmaceuticals/hormones – Military compounds – from manufacturing, testing, dismantling rockets – Industrial cleaners • PCBs – used in manufacturing plastics and insulating electrical transformers until 1979 • PBDEs – flame retardants
Oil Pollution
• • • Petroleum products – highly toxic to many marine organisms, birds, mammals Very difficult to remove Sources: – Drilling for undersea oil using offshore platforms – Spills from oil tankers – Natural seeps
Ways to Remediate Oil Pollution
• • • • Where does oil accumulate?
So how do we clean up surface oil?
– Containment using booms to keep the floating oil from spreading – Dispersants - chemicals that help break up the oil – Bacteria that are genetically engineered to consume oil But what about underwater plumes?
Treatment of rocky coastlines:
Other Water Pollutants
• • • • Solid waste pollution (garbage) Sediment pollution (sand, silt and clay) Thermal pollution Noise pollution
Solid Waste Pollution
• • Garbage - discarded materials from homes and industries that do not pose a toxic hazard to humans/other organisms – 1997 – scientists discovered the Great Pacific Garbage Patch – More of a problem in developing countries Coal ash and coal lag Contains harmful chemicals (lead, mercury, arsenic)
Sediment Pollution
• • Sediment – particles of sand, silt, clay – Carried by moving water – natural process Sediment pollution –increased movement of sediment due to human activities – Resulting from activities that loosen soil – Accounts for ~70% of sediment in waterways – Effects?
Thermal Pollution
• • Substantial change in water temperature – Can be increase or decrease, most commonly is increase – Methods to reduce thermal pollution: Thermal shock – dramatic change in temperature causing death to many species
Noise Pollution
• Sound emitted by ships/submarines – interfere with animal communication – Esp sonar
Water Laws
• • Clean Water Act- (1972) supports the “protection and propagation of fish, shellfish, and wildlife and recreation in and on the water” – Originated as the Federal Water Pollution Control Act of 1948 Issued water quality standards that defined acceptable limits of various pollutants in U.S. waterways
Water Laws
• Safe Drinking Water Act- (1974, 1986, 1996) sets the national standards for safe drinking water – Responsible for establishing maximum contaminant levels (MCL) for 77 different elements or substances in both surface water and groundwater • MCLs are subjective and subject to political pressure