Water Resources & Pollution Environmental Science

Water Cycle

How much water on Earth is available for human use?

Surface Water—fresh water found in lakes, rivers, streams, and wetlands

Surface water provides most of the water supply for large cities Resources Drinking water Water for crops Food- fish & shellfish Hydrologic power Transportation

Watershed– the area of land drained by a river Human impacts on watersheds Dams Re-routing rivers & tributaries Pollution runoff

Water table– level of groundwater Groundwater– stored beneath the Earth’s surface in sediment & rock formations Water table– level of groundwater In a desert, the water table could be hundreds of meters below the surface. In low-lying areas (New Orleans), the water table is at or right below the surface. Aquifer– underground formation of rocks, sand, & gravel where water accumulates Materials that are porous & permeable

Recharge Zone—the area of land above the aquifer that restores & replenishes its water supply Percolation Any pollution in the recharge zone can be introduced into the aquifer Man-made structures can act as a barrier for water replenishing the aquifer

Global Water Use 67% 14% 19% Residential Drinking Washing Cooking Toilets Agricultural Crops– irrigation Livestock Industrial Manufacturing Waste-disposal Power As cooling systems 67% 14% 19%

Water use varies by country

For residential use, water has to be treated to be potable

Water Management dams, canals, diversion projects Bring water to naturally drier areas Create reservoirs for drinking, recreation, power Interrupts natural water flow Disrupts ecosystems

Water Conservation In Agriculture In Industry In Residences Drip irrigation systems Developing crops that are drought-tolerant (need less water) In Industry Recycling cooling water & waste water Re-using “grey” water In Residences Xeriscaping Water-saving faucets, toilets, & shower heads

Water Pollution– the introduction of chemical, physical, or biological agents in to water that degrade water quality and adversely affect the organisms Most significant contributions to water pollution are industrialization & human population growth

Point-source pollution– comes from a single source (pipe)– factory, wastewater treatment plant, leaking tanker Nonpoint-source pollution non-specific source from runoff– roads, farms, construction, residential areas. Very difficult to identify.

Pollution Types Pollutant Agent Major Sources Pathogens Bacteria, viruses, parasites Mostly nonpoint; sewage, livestock feces, wastewater Organic Matter Decomposing material, debris from food waste Mostly nonpoint sources Organic Chemicals Pesticides fertilizers, plastics, detergents, oil Mostly nonpoint sources; golf courses, roads, wastewater Inorganic chemicals Acids, bases, industrial chemicals Point & nonpoint sources; industrial waste, roads, wastewater Heavy metals Lead, mercury, cadmium, arsenic Point & nonpoint sources; industrial discharge, landfills, household chemicals Physical agents Thermal pollution & solids Point & nonpoint sources; thermal pollution from industrial processes, suspended soil from erosion

Principle Sources of Water Pollution Wastewater Eutrophication Thermal pollution Groundwater Ocean Pollution

Wastewater– sewage or industrial waste Wastewater treatment involves filtration, aeration, settling, removal of semi-solid sludge, bacteria, and chlorination.

What to do about sludge? Treated sludge is mostly “safe” decomposing plant & animal material; however, sludge often contains high concentrations of toxic chemicals Some communities are developing ways to reduce toxins in the sludge, so it can be safely disposed or put to use (fertilizers or fuels)

Tertiary wastewater treatment Constructed wetlands offer another level of cleaning and filtration, naturally. They require no special chemicals, little extra energy.

Artificial Eutrophication– unnatural addition of nutrients to slow-moving waters Most artificial eutrophication comes from runoff of fertilizers and detergents, adding phosphates & nitrates to the water Causes excessive algae to grow When algae dies, decomposers/bacteria thrive in the water and deplete the oxygen Fish & other organisms suffocate

What can be done about eutrophication? Limit or eliminate phosphates in detergents Prevent runoff of nitrogen-containing fertilizers Use organic fertilizers Plant crops that need less fertilizers

Thermal Pollution– heated water is released from manufacturing or power plants Can cause large-scale fish kills Can cause the dissolved oxygen of the water to decrease What can be done about thermal pollution?

Groundwater Pollution– when pollution percolates down into aquifers pesticides, herbicides, chemical fertilizers Leaking underground storage tanks– commonly contain gas & heating oil Septic tanks, landfills, industrial wastewater Groundwater pollution is perhaps the most difficult type to control and clean up.

Ocean Pollution Runoff from activities on land causes 85% Oil spills Garbage & wastewater dumped directly from ships Even though major oil spills seem catastrophic… ten times more oil enters the ocean through nonpoint-source runoff each year.

Water pollution affects organisms all along the food chain Biomagnification– the accumulation of pollutants in the bodies of organisms going up the food chain. Tertiary consumers have much higher concentration of toxins in their bodies than primary producers or consumers.

Federal Water Pollution Legislation Year Legislation Requirements 1972 Clean Water Act Banned pollutant discharge into surface water; required metals be removed from wastewater 1972, 1988 Marine Protection, Research, and Sanctuaries Act Empowerd the EPA to control dumping of sewage and toxic chemicals in U.S. waters 1975, 1996 Safe Drinking Water Act Introduced programs to protect groundwater & surface water 1980 Superfund Act Required owners, operators, and customers of hazardous waste sites to be responsible for clean up 1987 Water Quality Act Supported state & local efforts to clean polluted runoff 1990 Oil Pollution Act Required oil tankers to be double-hulled in U.S. waters

What can individuals do to prevent water pollution? Refuse to support companies that fail to take responsibility Use phosphate-free detergents Prevent nonpoint-source pollution in your own yard– do not dispose toxic chemicals, clean up spills, keep car maintained Recycle– especially plastics Do not litter at the beach