Water Resources & Water Pollution Chapters 14 & 19

Importance of Water Effects on our planet: –Helps shape our continents –Moderates our climates –Allows organisms to survive Uses of fresh water: –drink it –cook with it –wash with it –travel on it –use it for agriculture –use it for energy production

Water’s Unique Properties  Hydrogen bonding  Liquid over wide temperature range  Changes temperature slowly  (high specific heat)  Changes temperature slowly  (high specific heat)  High heat of evaporation  Great dissolving power  pH – near neutral  Adhesion and cohesion properties  Expands when it freezes

All waterFresh waterReadily accessible fresh water Oceans and saline lakes 97.4% Fresh water 2.6% Groundwater 0.592% Ice caps and glaciers 1.984% Lakes 0.007% Soil moisture 0.005% Biota % Rivers % Atmospheric water vapor 0.001% 0.014% 97.4% Salt Water (Oceans and salt lakes)

Supply of Water Resources Fig p. 314 Freshwater 2.6% of all water on Earth Freshwater 2.6% of all water on Earth Readily accessible freshwater Biota % Biota % Rivers % Rivers % Atmospheric water vapor 0.001% Atmospheric water vapor 0.001% Lakes 0.007% Soil moisture 0.005% Groundwater 0.592% Groundwater 0.592% Ice caps and glaciers 1.984% 0.014%

Surface Water : Fresh water found on Earth’s surface in streams, rivers, lakes, ponds, reservoirs and wetlands. Runoff of precipitation from the land replenishes surface waters –Renewable resource Watershed (a.k.a. drainage basin): area of land that is drained by a single river or stream. –Size varies from 1km for a small stream to a huge area of the continent for major river systems like the Mississippi.

Ground Water : Underground formations that collect and store water in the ground. Originates as rain or melting snow that seeps into the soil and finds its way down through cracks and spaces in sand, gravel, or rock until it is stopped by an impenetrable layer. Flows through permeable sediments or rocks slowly (a couple mm/day) and eventually is discharged into rivers, wetlands, springs or the ocean. Aquifers: porous layers of sand, gravel or bedrock that are saturated with water (store ground water).

Evaporation and transpiration Evaporation Stream Infiltration Water table Infiltration Unconfined aquifer Confined aquifer Lake Well requiring a pump Flowing artesian well Runoff Precipitation Confined Recharge Area Aquifer Less permeable material such as clay Confirming permeable rock layer Ground Water

Types of Aquifers Unconfined Aquifers: form when layers of rock above are porous and allow surface water directly above them to seep downward replenishing the aquifer. –The upper limit of an unconfined aquifer, below which the ground is saturated with water, is the water table. Confined Aquifers: layers of rock above and below are impermeable. The water is trapped and often under pressure. –Artesian wells: take advantage of the pressure and tap confined aquifers (no pumps necessary).

Flooding Natural phenomena that renew and replenish water and nutrients. Flood damage is exacerbated by Deforestation Development of flood plains Floodplain Levee Flood wall Dam Reservoir

Use of Fresh Water Aquifer Depletion: removal of groundwater at a rate higher than it can be recharged by precipitation or melting snow. –Results in Subsidence (sinking of the land) Sinkholes (natural depression of land caused by removal of soil or bedrock, by water) Salt water intrusion Salinization: results from irrigation with groundwater that is rich in salts. These salts are left behind in the soil and decrease soil fertility.

Salt Water Intrusion Occurs mostly in very sandy areas close to the ocean, islands, spits, etc.

Water Shortages Population growth in arid climates within California, Nevada, Arizona and Florida has placed high demand on limited water supplies. To deal with this, water is imported from other areas. –Mono Lake in eastern California had surface water diverted to Los Angeles, lowering its water level and increasing its salinity. –Colorado River basin has been over-diverted for human consumption. –Ogallala Aquifer on the High Plains (S. Dakota, Nebraska) is the largest groundwater deposit in the world. The water table has dropped by 30 feet in some areas.

Transferring Water from One Place to Another North Bay Aqueduct North Bay Aqueduct South Bay Aqueduct South Bay Aqueduct California Aqueduct CALIFORNIA NEVADA UTAH MEXICO Central Arizona Project Colorado River Aqueduct Los Angeles Aqueduct Shasta Lake Sacramento Fresno Phoenix Tucson ARIZONA Colorado River Sacramento River Sacramento River San Francisco Los Angeles San Diego  California Water Project  Central Arizona Project Water is taken from one watershed and brought to another.

Acute shortage Adequate supply Shortage Metropolitan regions with population greater than 1 million

Use of Water Resources  Agriculture  Power plants  Domestic  Industry  Domestic  Industry United States Industry 11% Public 10% Power cooling 38% Agriculture 38%

Using Dams and Reservoirs to Supply More Water: dams ensure a year round supply of water in areas that have seasonal precipitation or snowmelt Large losses of water through evaporation Large losses of water through evaporation Flooded land destroys forests or cropland and displaces people Flooded land destroys forests or cropland and displaces people Downstream flooding is reduced Downstream cropland and estuaries are deprived of nutrient-rich silt Downstream cropland and estuaries are deprived of nutrient-rich silt Reservoir is useful for recreation and fishing Can produce cheap electricity (hydropower) Migration and spawning of some fish are disrupted Provides water for year-round irrigation of cropland

Problems with Using Groundwater  Saltwater intrusion  Chemical contamination  Reduced stream flows – because of diminished flows of groundwater into streams

Converting Salt Water to Fresh Water and Making it Rain Desalinization: the removal of salt from seawater or salty groundwater. –Distillation: boil water then condense vapor, salt is left behind (high energy usage). –Reverse Osmosis: forces saltwater through a membrane that is permeable to water but not to salt (more energy efficient). –Disadvantages include high expenses and the creation of “brine” which is wastewater with high levels of salts and minerals Cloud Seeding: providing particles for water to condense on (like salt crystals) can increase the likelihood of rain fall.

Using Water More Efficiently  Reduce losses due to leakage  Reform water laws  Improve irrigation efficiency: Micro irrigation and field leveling can cut agricultural water consumption.

Water Pollution : any change (physical or chemical) in water that adversely affects the health of humans and other organisms. Causes of Water Pollution –Sewage –Disease causing agents –Sediments –Inorganic plant and algal nutrients –Organic compounds –Inorganic compounds –Radioactive substances –Thermal pollution

Point and Nonpoint Sources NONPOINT SOURCES Urban streets Suburban development Wastewater treatment plant Rural homes Cropland Factory Animal feedlot POINT SOURCES

Sewage –Microorganisms use the process of cellular respiration to break down sewage into CO 2, H 2 O and other materials. –Biochemical Oxygen Demand (BOD) is the amount of oxygen needed by microorganisms to decompose sewage and other organic wastes. Wastewater carried off by drains or sewers, contributes to enrichment (fertilization of water) and produces oxygen demand as it is decomposed.

Disease Causing Agents Bacteria, viruses, protozoans, and parasitic worms are all transmitted in sewage. E. coli (a common intestinal bacteria) are used as an indication of the amount of sewage present in a body of water and as an indirect measure of disease causing organisms. The fecal coliform test is used to determine the presence of E. coli in water.

Sediment Pollution Caused by soil erosion Increases water turbidity Reduces photosynthetic productivity Can be measured with a Secchi disk

Inorganic plant and algal nutrients These include things like nitrogen and phosphorous which will enrich the environment. Fertilizer runoff from agricultural and residential land is the major contributor Increased levels of nutrients eventually leads to decreasing oxygen levels in the water. This condition is known as hypoxia.

Organic Compounds Contain carbon Synthetic Persistent Examples: pesticides, solvents, industrial chemicals Generally these are highly toxic (often carcinogenic).

Inorganic Chemicals Contaminants that contain elements other than carbon. This group includes toxins like lead and mercury. –Lead: most lead contamination results from human activities. The health consequences of lead poisoning in children include: Partial hearing loss, hyperactivity, attention deficit, lowered IQ and learning disabilities. –Mercury: used in many industrial processes and is released during the combustion of coal. One is a body of water mercury is converted to methyl mercury, which readily enters the food web and accumulates in fish. Methyl mercury compounds are highly toxic.

Radioactive Substances Sources include mining wastes, refining and medical wastes. Radioactive substances may concentrate in sewage sludge. Thermal Pollution Occurs when heated water, produced during many industrial processes is released into waterways. Warm water has a lower capacity to hold dissolved gases…

Eutrophication : Nutrient enrichment of oligotrophic lakes, estuaries or slow-moving streams. Results in high photosynthetic productivity, which supports an overpopulation of algae (algal bloom). Eutrophic bodies of water tend to fill in rapidly as dead organisms settle to the bottom. Eutrophication kills fishes and causes a decline in water quality as large numbers of algae die and decompose rapidly (high BOD results in a drop in DO, hypoxia). Artificial Eutrophication (a.k.a. cultural eutrophication) is the enrichment of an aquatic ecosystem that occurs at an accelerated rate because of human activities such as fertilizer runoff and sewage.

Pollution of Streams  Oxygen sag curve Oxygen demand in blue and oxygen sag in orange.

Pollution of Lakes  Eutrophication  Slow turnover  Thermal stratification

Groundwater Pollution Coal strip mine runoff Pumping well Waste lagoon Accidental spills Groundwater flow Confined aquifer Discharge Leakage from faulty casing Hazardous waste injection well Pesticides Gasoline station Buried gasoline and solvent tank Sewer Cesspool septic tank De-icing road salt Unconfined freshwater aquifer Confined freshwater aquifer Water pumping well Landfill Sources include: sanitary landfills, underground storage tanks, agricultural operations Recovery is slow because temperatures are low and the flow rate is slow.

Groundwater Pollution Prevention  Monitoring aquifers  Leak detection systems  Strictly regulating hazardous waste disposal  Storing hazardous materials above ground

Ocean Pollution

Oil Spills  Sources: offshore wells, tankers, pipelines and storage tanks  Effects: death of organisms, loss of animal insulation and buoyancy because of oil coating, smothering  Significant economic impacts  Takes about 3 years to recover from crude oil spills and about 10 years for refined oil  Significant economic impacts  Takes about 3 years to recover from crude oil spills and about 10 years for refined oil  Mechanical cleanup methods: skimmers and blotters  Chemical cleanup methods: coagulants and dispersing agents

Solutions: Preventing and Reducing Surface Water Pollution  Reduce runoff  Buffer zone vegetation  Reduce soil erosion  Clean Water Act ( 1972): improved number of lakes and rivers being tested, minimized amount of topsoil lost through agricultural runoff, more sewage treatment plants put into place, and decreased wetland loss - requires the EPA to establish nation emission limitations for wastewater that is discharged into US surface waters.

Solutions: Preventing and Reducing Surface Water Pollution Safe Drinking Water Act (1974): requires the EPA to establish maximum contaminant levels for water pollutants that might affect human health Water Quality Act (1987): to control surface water pollution It is easier to control point sources than nonpoint sources.

Waste Water Treatment Primary treatment: physical settling of solids. Secondary treatment: biological degradation of organic wastes. Tertiary treatment: removal of special contaminants such as organic chemicals, nitrogen, and phosphorous. Sludge: slimy mixture of bacteria-laden solids that settle out during sewage treatment (primary sludge & secondary sludge). –Can be treated and then used as fertilizer if there are not high levels of toxins.

Technological Approach: Septic Systems  Require suitable soils and maintenance CAUTION! Do not place too close to wells.

Technological Approach: Sewage Treatment  Mechanical and biological treatment

Technological Approach: Advanced Sewage Treatment  Removes specific pollutants Often, only 1 or 2 of these processes is used to remove specific pollutants in a particular area. It is very expensive and therefore, not widely used.

Technological Approach: Using Wetlands to Treat Sewage

Drinking Water Quality 1.4 billion people do not have access to safe drinking water. –Contaminated with hazardous chemicals or disease causing agents. 2.9 billion people do not have access to adequate sanitation systems. –Results in contaminated drinking water. –Increased rates of disease.