Chapter 14 Water Pollution

The Chesapeake Bay Chesapeake Bay – largest estuary in the US Pollutants: – Excess nitrogen and phosphorus From 3 major sources: Consequence – Sediment increase Causes: – Anthropogenic chemicals 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 source pollution Nonpoint source pollution

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 wastewater from contaminating drinking water

Human Wastewater 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

Human Wastewater 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

Human Wastewater Nutrient Release Nutrients (ie phosphorus, nitrogen) present from human wastewater Eutrophication – increase in fertility of a body of water – Cultural eutrophication Ex: Dead Zone in the Gulf of Mexico

Human Wastewater Why is eutrophication a bad thing? Sewage ↑ Enrichment Explosion in algal, bacteria & decomposer populations ↑ Biological oxygen demand (BOD) ↓ Oxygen levels in water Fish kills

Human Wastewater Disease-causing Organisms Pathogens – illness-causing viruses, bacteria and parasites – Illnesses include: Indicator species Fecal coliform bacteria test

Human Wastewater Treatments 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:

Human Wastewater Treatments Sewage Treatment Plants- centralized plants in areas with large populations that receive wastewater via a network of underground pipes – Primary treatment – Secondary treatment Problems?

Human Wastewater What is removed…

Human Wastewater 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 – 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 – Can cause:

Acid Deposition and Acid Mine Drainage Acid deposition – Wet deposition vs. Dry deposition – What’s being done to prevent? Acid mine drainage – Lower pH = harmful metal ions become water soluble – What can be done? – Problem

Synthetic Organic Compounds Synthetic – human made Includes: – Pesticides 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

Oil Pollution Ways to Remediate Where does oil accumulate? So how do we clean up surface oil? – Containment? – Dispersants - chemicals that help break up the oil – Bacteria that are genetically engineered to consume oil Underwater plumes Treatment of rocky coastlines:

Non-Chemical 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 Sediment pollution –increased movement of sediment due to human activities – Activities that loosen soil – Effects?

Thermal Pollution Substantial change in water temperature – Can be increase or decrease, most commonly is increase – Methods to reduce thermal pollution: Thermal shock

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

We still have work to do…