Chapter Fourteen: Water Pollution

Point Source

A distinct location from which pollution is directly produced - ex. a sewage lines breaks

Non-Point Source

A more diffused area that produces pollution - not traced to one spot - ex. many in the town use fertilizer

Biological Oxygen Demand (BOD)

The amount of oxygen a quantity of water uses over a period of time at a specific temperature - nitrates and phosphates from fertilizer cause bacteria/algal growth which take up tons of oxygen (causes dead zones)

Disease-Causing Organisms

Viruses, bacteria, and protozoa - water-borne illnesses include cholera, hepatitis, and typhoid fever - you can use an indicator species to test whether DCOs are present

Indicator Species

Organism where its presence/absence/abundance alerts scientists of an environmental condition - these can test whether disease-causing organisms are present - ex. fecal coliform bacteria in water is an indicator of E. Coli, or a lack of wood storks means their food source isn’t there for some reason (pH, pollution)

Septic Tanks and Their Layers

Receives wastewater from homes, flows in one end and out the other - over time three layers develop:

1. Sludge: solid waste material, including pathogens

2. Septage/Wastewater: middle layer of fairly clear water, contains bacteria

3. Scum

Seeps into leach fields

Leach Field

Made of underground pipes below the ground - septage seeps into the fields and is eventually taken up by plants

Primary Sewage Treatment

Solid waste settles into a sludge layer

Secondary Sewage Treatment

Use of bacteria to break down organic matter - aerates water to help the growth of aerobic bacteria - disinfectant is used to kill harmful microorganisms - the combined sludge from primary and secondary treatment must be sent to a landfill, burned, or turned into fertilizer

Sewage Contamination

Raw sewage can be pumped into rivers and lakes - treatment plants can be overwhelmed with the combination of stormwater and wastewater and at times are allowed to bypass treatment and put it into a local water supply - this is a problem more in older cities in the Northeast and Midwest - contaminates drinking water, beaches, fish, shellfish, and leads to waterborne illnesses - modernization of sewage treatment needs to happen but is costly - animal waste also contaminates water

Manure Lagoon

Large, lined, humanmade pond - used to dispose of large amount of animal waste - bacteria break down the manure and it can eventually be used as fertilizer

Lead

Heavy metal that comes from lead-lined pipes, brass fittings, and solder - fetuses and infants exposed can lead to damage of the brain, nervous system, and kidneys

Arsenic

Natural-occurring heavy metal in crust, wood preservatives - can be removed from water by filters, reverse osmosis - can cause cancer of the skin, lungs, kidneys, and bladder

Mercury

Naturally-occurring heavy metal from the burning of coal, burning of trash, making of cement, and in medical/dental supplies - accumulates in fish - leads to nervous system problems

Acid Deposition and Acid Mine Drainage

Acids can be deposited from rain, snow, or as gases and particles that attach to plants, soil, and water - combustion of fossil fuels releases sulfur and nitrogen oxides - mines can lower the pH of water from underground as pyrite breaks down into iron and hydrogen ions (acidic)

Synthetic Organic Compounds

Pesticides cause biomagnification - inert ingredients found in pesticides as additives to make the pesticide more effective include these compounds (ex. roundup) - synthetic oils, fuels, solvents

Pollution of Pharmaceuticals and Hormones

Many are found in water and streams - antibiotics, reproductive hormones, steroids, over-the-counter medications - found at low levels, but low levels of hormones can enter into the tissues of organisms and contaminate/harm them

Percholates

Harmful chemicals used for rocket fuel that can contaminate the soil - easily leach into groundwater - affects thyroid

Polychlorinated Biphenyls (PCBs)

Once used to manufacture plastics and insulate transformers - banned in the US since 1977 but extremely persistent in the environment (binds to soil)

PolyBrominated Diphenyl Ethers (PBDEs)

Flame retardants that are found in fish and birds - biomagnification

Oil Pollution

From spills, offshore drilling, and oil tankers (ex. exxon valdez, deepwater horizon) - can naturally seep into the ocean floor - harmful to the environment, birds, fish, and mammals

Oil Remedation

• Containment of oil using plastic barriers on the surface of the water that extend down several meters - then, as much oil as possible is sucked up

• Chemicals can be applied to the surface but it can be toxic to animals

• Burning of oil slicks creates air pollution

• Use of bacteria that obtain energy by consuming oil

• No method to clearn underground water plumes

Solid Waste Pollution

Garbage and sludge from sewage treatment plants, great pacific garbage patch, coal ash, and coal tailings (deemed “special waste”)

Sediment Pollution

From construction, plowed agricultural fields, removal of natural vegetation - reduces sunlight (no photosynthesis so dissolved oxygen decreases) - clogs gills - increase of nutrients

Thermal Pollution

From power plants, steel mills, and paper mills - thermal shock is a dramatic change in water temperature that can kill organisms - increases organisms’ respiration rate - cooling towers, cooling ponds and artificial lakes can help

1972 Clean Drinking Water Act

Focuses on point sources - mainly on chemical properties of surface waters - recently focusing on biological properties - defines limits of various pollutants

1996 Updated Safe Drinking Water Act

EPA regulates about 77 elements and substances on the surface and groundwater (sets standards) - nonpoint source pollution is difficult to regulate - fracking is exempt