Presentation on theme: "Review Day 2. Human Diet Math Problem If an average refrigerator uses 500 watts of energy per hour on a daily basis, and your energy cost is $0.11 per."— Presentation transcript:
Review Day 2
Math Problem If an average refrigerator uses 500 watts of energy per hour on a daily basis, and your energy cost is $0.11 per kwh, approximately how much does the energy used by the refrigerator cost per month? a. $1.30 b. $13 c. $40 d. $55 e. $132
Long Division... Last time. 10/5 176/160 1305/30
Water Review Water Pollution
WATER POLLUTION: SOURCES, TYPES, AND EFFECTS Water pollution is any chemical, biological, or physical change in water quality that has a harmful effect on living organisms or makes water unsuitable for desired uses. Point source: specific location (drain pipes, ditches, sewer lines). Nonpoint source: cannot be traced to a single site of discharge (atmospheric deposition, agricultural / industrial / residential runoff)
Major Water Pollutants and Their Effects
Water quality and dissolved oxygen (DO) content in parts per million (ppm) at 20°C. Only a few fish species can survive in water less than 4ppm at 20°C.
POLLUTION OF FRESHWATER STREAMS Most developed countries have sharply reduced point- source pollution but toxic chemicals and pollution from nonpoint sources are still a problem. Stream pollution from discharges of untreated sewage and industrial wastes is a major problem in developing countries.
Cultural Eutrophication Eutrophication: the natural nutrient enrichment of a shallow lake, estuary or slow moving stream, mostly from runoff of plant nutrients from the surrounding land. Cultural eutrophication: human activities accelerate the input of plant nutrients (mostly nitrate- and phosphate-containing effluents) to a lake. 85% of large lakes near major population centers in the U.S. have some degree of cultural eutrophication.
Coal strip mine runoff Polluted air Deicing road salt Pesticides and fertilizers Hazardous waste injection well Pumping well Gasoline station Water pumping well Landfill Sewer Buried gasoline and solvent tanks Cesspool, septic tank Groundwater flow Confined aquifer Confined freshwater aquifer Unconfined freshwater aquifer Accidental spills Waste lagoon Leakage from faulty casing Discharge
POLLUTION OF GROUNDWATER It can take hundreds to thousand of years for contaminated groundwater to cleanse itself of degradable wastes. Nondegradable wastes (toxic lead, arsenic, flouride) are there permanently. Slowly degradable wastes (such as DDT) are there for decades.
Aquifer Water well Migrating vapor phase Contaminant plume moves with the groundwater Free gasoline dissolves in groundwater (dissolved phase) Groundwater flow Water table Gasoline leakage plume (liquid phase) Leaking tank Bedrock
Solutions Groundwater Pollution CleanupPrevention Find substitutes for toxic chemicals Install monitoring wells near landfills and underground tanks Require leak detectors on underground tanks Ban hazardous waste disposal in landfills and injection wells Store harmful liquids in aboveground tanks with leak detection and collection systems Pump to surface, clean, and return to aquifer (very expensive) Pump nanoparticles of inorganic compounds to remove pollutants (may be the cheapest, easiest, and most effective method but is still being developed) Keep toxic chemicals out of the environment Inject microorganisms to clean up contamination (less expensive but still costly)
Fig. 21-10, p. 505 Healthy zone Clear, oxygen-rich waters promote growth of plankton and sea grasses, and support fish. Oxygen-depleted zone Sedimentation and algae overgrowth reduce sunlight, kill beneficial sea grasses, use up oxygen, and degrade habitat. Red tides Excess nitrogen causes explosive growth of toxicmicroscopic algae, poisoning fish and marine mammals. Farms Runoff of pesticides, manure, and fertilizers adds toxins and excess nitrogen and phosphorus. Toxic sediments Chemicals and toxic metals contaminate shellfish beds, kill spawning fish, and accumulate in the tissues of bottom feeders. Construction sites Sediments are washed into waterways, choking fish and plants, clouding waters, and blocking sunlight. Urban sprawl Bacteria and viruses from sewers and septic tanks contaminate shellfish beds Oxygen-depleted zone Closed beach Cities Toxic metals and oil from streets and parking lots pollute waters; Industry Nitrogen oxides from autos and smokestacks, toxic chemicals, and heavy metals in effluents flow into bays and estuaries. Closed shellfish beds
OCEAN POLLUTION Harmful algal blooms (HAB) are caused by explosive growth of harmful algae from sewage and agricultural runoff.
Reduce input of toxic pollutants Solutions Coastal Water Pollution PreventionCleanup Use wetlands, solar-aquatic, or other methods to treat sewage Require at least secondary treatment of coastal sewage Sprinkle nanoparticles over an oil or sewage spill to dissolve the oil or sewage without creating harmful by-products (still under development) Improve oil-spill cleanup capabilities Recycle used oil Regulate coastal development Protect sensitive areas from development, oil drilling, and oil shipping Ban ocean dumping of sludge and hazardous dredged material Ban dumping of wastes and sewage by maritime and cruise ships in coastal waters Separate sewage and storm lines Require double hulls for oil tankers
Reducing Water Pollution through Sewage Treatment Raw sewage reaching a municipal sewage treatment plant typically undergoes: Primary sewage treatment: a physical process that uses screens and a grit tank to remove large floating objects and allows settling. Secondary sewage treatment: a biological process in which aerobic bacteria remove as much as 90% of dissolved and biodegradable, oxygen demanding organic wastes.
Reducing Water Pollution through Sewage Treatment Primary and Secondary sewage treatment.
Prevent groundwater contamination Solutions Water Pollution Reduce birth rates Reduce poverty Reduce air pollution Practice four R's of resource use (refuse, reduce, recycle, reuse) Work with nature to treat sewage Find substitutes for toxic pollutants Reuse treated wastewater for irrigation Reduce nonpoint runoff
Environmental Organizations and Industries http://webecoist.momtastic.com/2008/09/24/25-environmental- agencies-and-organizations/