Freshwater Resources Freshwater Systems 97 5 of Earth

Freshwater Resources

Freshwater Systems � 97. 5% of Earth is water, only 2. 5% is freshwater �Freshwater – water that is relatively pure, with few dissolved salts �Most freshwater is locked up in polar icecaps and icebergs, and underground aquifers � Only 1 part in 10, 000 is available for human use

�Hydrologic Cycle �Water carries nutrients and sediments to the oceans from rivers �Distributes nutrients and sediments in the ocean through currents �Hydrologic cycle – summarizes how water in its three forms flow through our environment � Evaporation – conversion of liquid water into a gaseous state � Warm temperatures speed up evaporation � Areas of less growth will lose more water � Transpiration – release of water vapor from plants through their leaves � Strong winds and/or higher temperatures speed up transpiration

�Precipitation- water vapor condenses and falls as rain or snow from Earth’s atmosphere � Plants will use water this way � Most is lost as runoff into lakes, ponds, rivers, oceans, and streams �Groundwater – water under the surface that gets recharged by precipitation or surface water � Water soaks through into aquifers � Water table – the upper limit of groundwater held in an aquifer, aquifer

Human Impacts on the Hydrologic Cycle - damming rivers creating reservoirs -destroys habitat by flooding land previously not underwater

Impacts con’t �Increase evaporation by clearing lands �Increase surface water and runoff �By eliminating farm lands and forest, we reduce the amount of vegetation, reducing transpiration �Overdrawing groundwater for use depleting our water resource

How we use water �Household use, Agricultural, and Industry �Nations with dry climates use more water for agriculture. �Heavily industrialized nations use more water. �Globally, we use 70% of freshwater for agriculture, 20% for industry, and residential/municipal accounts for 10%.

�Types of Use � Consumptive Use – we remove water from an aquifer or surface water and do not return it � Nonconsumptive Use – water does not remove, or only temporarily removes water from an aquifer or surface water body � Example: Dam

Surface Water �Surface water – water found on Earth’s Surface � Sources include rainfall, melting snow, glaciers, and ice caps � Surface water moves from these sources to bodies of surface water as runoff �Runoff – water that flows over land that is not absorbed into the ground �River system – network of connected streams and rivers that form as water moves downhill �Water moves in the following progression � Shallow groves in the Earth’s crust stream small river (tributaries) large body of water stream large river

River Systems of NJ Mullica River System

�Watersheds – includes all of the land area that supplies water to a particular river system �Watershed structure – there are 9 major watersheds that make up the US � Each is made up of many different watersheds �Managing Watersheds – upstream pollution will have negative effects on the downstream watershed � Requires cooperation of all individuals who live within the watershed

Using Surface Water �Diverting water �Water diversion – the process of moving from its source to places where humans use it � Dam – an obstruction placed in a river or stream to block its flow � Creates an artificial reservoir (lakes that store water for human use) � There are 80, 000 dams in use in the US. � Canal – water diverted from a river to irrigate farmlands that are not near any surface water resources

Costs and Benefits of Dams Costs Benefits �Habitat alteration �Fisheries decline �Population displacement �Sediment capture �Loss of fertile farmland �Risk of failure �Lost recreational opportunities �Clean power generation � Hydroelectric �Crop irrigation �Flood control �Shipping �New recreational opportunities

�Surface water depletion �Drought and overuse contribute most to depletion of surface water � Dried-up rivers – too much water is diverted upstream, therefore, eliminating water flow downstream in heavily used areas � The Aral Sea – two rivers were diverted to irrigate thirsty cotton fields � The rivers flood the Aral Sea, but since the diversion, the sea has shrunk to 10% of its original size. � 60, 000 fishing jobs were lost.

Using Groundwater �Groundwater is being used primarily for irrigation faster than it can be replenished. �Agricultural Uses – 26% of the freshwater used in the US comes from groundwater; of that 68% is used for irrigation �Most water is lost to run-off and evaporation �Too much water can be detrimental. � Waterlogging – the soil becomes saturated with water to the point that oxygen no longer gets in � Salinization – buildup of salts in the surface layers of soil.

�Groundwater Mining � 18% of groundwater goes to public use for drinking, washing, etc. . � Groundwater mining – using groundwater faster than it can be replaced � Turn water into a nonrenewable resource � Lowers the amount of water in aquifers � Drops the water tables – causes land over top to become weak, not being able to support it � Sinkholes – areas where the ground gives way swallowing up everything on the surface

�Groundwater Depletion �As mining increases, the volume of water in the aquifer decreases �As groundwater leaves, salt water travels through cracks in the stone contaminating the remaining freshwater with high salt concentrations. �Causes streets to buckle, buildings that flood, pipes to break, building to lean.

http: //edro. wordpress. com/2008/02/

Solutions to Freshwater Depeletion �Solutions that increase supply �Desalination – the technology of removing salt from saltwater to make freshwater � Methods One method: boiling seawater to produce water vapor, then condense (cool) the vapor in order to collect the water � Reverse osmosis – forces water through artificial membranes to filter out salts � Very expensive � Requires a lot of Energy �

�Solutions that Reduce Demand �Agricultural Solutions � Drip irrigation system � Less water lost to evaporation � Climate-appropriate crops � Less water needed to grow �Industrial Solutions � Companies have contracts with municipalities for certain amounts of water; recycle wastewater �Personal Solutions � Watering at night � Chose outdoor plants adapted to the conditions � Called xeriscaping � Low flow toilets, showers, sinks � Fixing leaky pipes

Water Pollution �Types of Water Pollution �Point-Source Pollution – pollution that comes from a distinct locations such as a factory or sewer pipe �Nonpoint-Source Pollution – pollution that comes from many places over a large area � Watershed pollution carries all runoff to large bodies of water

�Nutrient Pollution – areas of water that have a high nutrient content but low oxygen content are called eutrophic �Eutrophication – natural process of the build up of nutrients in a body of water � Freshwater usually has a build-up of phosphorus � How it happens; � As phosphorus levels rise, so does the population of algae and aquatic plants � More growth means more death; which leads to decomposition of dead organic material � Decomposition requires oxygen which lowers the oxygen levels in the water � End result is a high nutrient low oxygen containing body of water…………. . Eutrophic

�Cultural Eutrophication – nutrient pollution by humans, also called artificial eutrophication �Usually occurs because of non-point source pollution from fertilizers and detergents carried in runoff � Causes algal blooms – explosions in algal populations due to the increase in phosphorus � May cover the entire surface of a body of water; blocks sunlight for photosynthesis, decomposition increases, oxygen levels decrease

�Toxic-Chemical Pollution – organic or inorganic pollutants in the freshwater �Petroleum (plastics, mercury, arsenic, lead) �Sediment Pollution – more sediment being deposited down river causing photosynthesis rates to change, causing food webs to collapse �Is a result of erosion; mostly man-made. �Thermal Pollution – the warmer water is, the less oxygen it can hold (increased molecular motion) �Industrial processes use water to cool down machinery � When the water is returned, it is warmer than when it started �Removal of trees; addition of trees

�Biological Pollution – disease causing pathogens make their way into soil and water �Human or animal waste �Causes more health problems than any other pollution type �Access to clean water will reduce the death toll due to contaminated drinking water � Most deaths occur in South Asia and sub-Saharan Africa in young children

Groundwater Pollution �Sources �Human intervention is the reason why groundwater pollution is so widespread. � Chemicals from fertilizers and pesticides leach down (soak) into aquifers. � Leaky wells and faulty storage tanks from industry also add to this problem.

�Cleaning up Groundwater �Natural processes do filter away pollutants, however, it takes many years. � DDT is still found in underground water although its use was banned in 1972. �Decomposition is slower in groundwater than in surface water. � Why? Less microbes, does not move as much, takes a long time to recharge �How can groundwater be cleaned up? � Locate and repair gasoline tanks, sewage tanks, oil tanks, etc. .

Ocean water Pollution �Oil Pollution �Most oils spillage comes from small nonpoint-sources such as small boats, runoff from human activities on land. �Oil coats and kills marine organisms, shattering food webs. �Oil Pollution Act – set aside $1 billion for prevention and cleanup � Mandates leaks that oil tankers have a double hull to prevent oil

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�Mercury Pollution �Mercury is a toxic heavy metal that collects in the tissues of marine organisms. �Makes its way up the food chain by biological magnification.

Biological Magnification of DDT in a Food Chain Concentration of DDT in A Long Island Marsh sprayed for Mosquito Control 1967 ppm Water . 00005 Plankton . 04 Silverside Minnow . 23 Sheephead Minnow . 94 Pickerel 1. 23 Needlefish 2. 07 Heron 3. 57 Tern 3. 91 Osprey 13. 8 Merganser 22. 8 Cormorant 26. 4

�Nutrient Pollution in the Ocean �Nitrogen effects the oceans in the same way phosphorus effects freshwater systems. �Red Tides – algal blooms in the ocean cause red pigments to be produced and released into the food chain. � Pigments may cause illness and death among zooplankton, fish, marine mammals, birds, and humans. �The only way to stop this is to reduce nutrient runoff from land.

Controlling Water Pollution �The Clean Water Act of 1977 �Made it illegal to release pollution from point source without a permit �Set standards for pollution levels in surface water and industrial wastewater �Water Treatment �Drinking water treatment – EPA set standards for 80 possible contaminants �Wastewater Treatment – water from homes, industry, farming

Water Treatment Facility

Septic System Septic systems are the most popular method of wastewater disposal in rural areas of the U. S.