Water: Resources and Water Pollution
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DESCRIPTIONWater: Resources and Water Pollution. Chapter 11. Planet Earth: the water planet. http:// sealevel.jpl.nasa.gov /images/videos/The_Water_Planet_264.mov. Ocean Currents. NASA Visualization of Ocean Currents. The Hydrologic Cycle. The Hydrologic Cycle Constantly Redistributes Water. - PowerPoint PPT Presentation
Water: Resources and Water PollutionChapter 111Planet Earth: the water planethttp://sealevel.jpl.nasa.gov/images/videos/The_Water_Planet_264.movOcean CurrentsNASA Visualization of Ocean Currents
33The Hydrologic Cycle
4The hydrologic cycle. Most exchange occurs with evaporation from oceans and precipitation back to oceans. About one-tenth of water evaporated from oceans falls over land, is recycled through terrestrial systems, and eventually drains back to oceans in rivers.4The Hydrologic Cycle ConstantlyRedistributes WaterWater cycles through environmentDescribe cycle: evaporation from moist surfaces/waterprecipitationrun-off (rivers/lakes); soil percolation (ground water)through living organismssolar energy drives the hydrologic cycle water and sunlight are unevenly distributed around the globe, thus water resources are very uneven5The water we use cycles endlessly through the environment. The total amount of water on our planet is immensemore than 1,404 million km3 (370 billion billion gal) (table 11.1). This water evaporates from moist surfaces, falls as rain or snow, passes through living organisms, and returns to the ocean in a process known as the hydrologic cycle (see fig. 2.17). Every year, about 500,000 km3, or a layer 1.4 m thick, evaporates from the oceans. More than 90 percent of that moisture falls back on the ocean. The 47,000 km3 carried onshore joins some 72,000 km3 evaporated from lakes, rivers, soil, and plants to become our annual, renewable supply of fresh water. Plants play a major role in the hydrologic cycle, absorbing groundwater and pumping it into the atmosphere by transpiration (transport plus evaporation). In tropical forests, as much as 75 percent of annual precipitation is returned to the atmosphere by plants.
Solar energy drives the hydrologic cycle by evaporating surface water, which becomes rain and snow. Because water and sunlight are unevenly distributed around the globe, water resources are very uneven. At Iquique in the Chilean desert, for instance, no rain has fallen in recorded history. At the other end of the scale, 26.5 m (86.8 ft) of rain was recorded in 1860 in Cherrapunji in India. Figure 11.2 shows current patterns of precipitation around the world, but climate change is altering that map. Cherrapunji, for example, only receives about one-third as much rain today as it did a century ago.5Mean Annual Precipitation
6The distribution of precipitation in different parts of the earth is certainly not even. Lack of precipitation, either regularly or seasonally, is the source of enormous human suffering. The amount of precipitation a particular area receives largely dictates the nature of vegetation and animals there. Such human suffering is prevalent in northern Africa where this map shows that less than 25 cm (10 inches) of rain falls per year. Water in the World
water covers 71% of earths surface
7Unique Properties of Waterdue to molecular structure
OHH-++a polar molecule - excellent solventadhesionhydrogen bondingbetween water moleculesbetween water and other moleculescohesionOHH-++OHH-++OHH-++tensile strengthcapillarity - from cohesion and adhesion 8
9Case Study: Ch 11, When will Lake Mead go dry?
Case Study: Ch 11, When will Lake Mead go dry?Reasons for dams?flood controlelectricity generationwater sourcerecreation11I tell you gentlemen; you are piling up a heritage of conflict and litigationof water rights, for there is not sufficient water to supply the land.
John Wesley Powell (1893)Case Study: Ch 11, When will Lake Mead go dry?12Case Study: When will Lake Mead go dry?
11-1313The Colorado River is the lifeblood of the American Southwest. More than 30 million people and a $1.2 trillion regional economy in cities, such as Los Angeles, Phoenix, Las Vegas, and Denver, depend on its water. But the sustainability of this essential resource is in doubt. Drought, climate change, and rapid urban growth are creating worries about the future of the entire watershed. In 2008, Tim Barnett and David Pierce from the Scripts Institute in California published a provocative article suggesting that both Lake Mead and Lake Powell could reach levels within a decade or so at which neither would be able to either produce power or provide water for urban or agricultural use if no changes are made in current water allocations. The roots of this problem can be traced to the Colorado Compact of 1922, which allocated water rights for the seven states that adjoin the river. The previous decade had been the wettest in more than a thousand years. The estimated annual river flow of 18 million acre-feet (22 billion m3) negotiators though they could allocate was about 20 percent higher than the 20th century average.
As cities have grown, however, and agriculture has expanded over the past century, competing claims for water have repeatedly caused tensions and disputes. climate change is expected to decrease river flows by 10 to 30 percent over the next 50 years. There may be only half as much water in the river in a few decades as negotiators once thought they had to distribute between the states. Since the year 2000, water level in Lake Mead in Nevada has been dropping about 12 feet (3.6 m) per year. Estimates are that without changes in current management plans, theres a 50 percent chance minimum power pool levels in both Lakes Mead and Powell will be reached by 2017 and that theres an equal chance that live storage in both lakes will be gone by about 2021. Already, were at or beyond the sustainable limits of the river. Currently, Lake Mead is only 43 percent full and Lake Powell holds 58 percent of its maximum volume. The shores of both lakes now display a wide "bath-tub ring" of deposited minerals left by the receding water.
The American Southwest isnt alone in facing this problem. The United Nations warns that water supplies are likely to become one of the most pressing environmental issues of the twenty-first century. By 2025, two-thirds of all humans could be living in places where water resources are inadequate. 13
11-14LAKE MEAD, Nev. The sinuous Colorado River and its slew of man-made reservoirs from the Rockies to southern Arizona are being sapped by 14 years of drought nearly unrivaled in 1,250 years.Colorado River Drought Forces a Painful Reckoning for States, New York Times, MICHAEL WINES JAN. 5, 2014The Colorado River System14Unique Properties of Water1. liquid over wide range of temperatures due to cohesionboiling = 100C (212F)freezing = 0C (32F)2. high heat capacity (slowly changes temperature)stores heat well and can resists temperatures changescoastal areas have less temperature fluctuations than continental areasmoderates earth temperature3. requires much energy to evaporate skin furnishes heat and thus cools body15Unique Properties of Water4. great solvent (of polar compounds)polarity of water molecule keeps ions apartsalt (NaCl) ionizes in water
16Unique Properties of Water5. surface tension and high wetting abilitycohesion and adhesion cause water to rise in plants
as water evaporates from the leaf surface, a column of wateris pulled upward from the soil water17Unique Properties of Water6. Expands when freezesice floats (insulates)7. Density increases as temperature decreases: most dense at 4C
bodies of water (lakes and streams) remain liquid in winterturnover can occur in lakes in spring and fall18Surface Waterwater that remains on earths surface as a result of precipitationwater in streams, lakes, wetlands, reservoirswatershedland region draining into a body of waterStagecoach Lakein lab we determined that lakes watershedImpact of Rachel Carsons Silent Spring19Biological Amplificaiton10,000,000Xincrease in concentration
Rachel Carson, 1962 Silent Spring20Biomagnification contdClear Lake, California (90 mi N San Francisco)copious numbers of gnats (not a mosquito)1949 - DDD (DDT relative) applied to lake1 part DDD : 70,000,000 parts water1/70 parts per million1954 - control repeated (now not as affective)1 part DDD : 50,000,000 parts water1/50 parts per million1955 Western Grebes starting to die1957 - 3rd wave of DDD applicationmore Western Grebes die; analysis of bird tissue:1600 parts DDD per million112,000 X increase in concentration21
22Ground Waterwater that percolates downward through spaces in soil and rockzone of aerationupper soil layers that hold both air and waterzone of saturationregion of rock and soil that always maintains water in the spaceswater table begins at the zone of saturationaquiferwater-saturated layers of rock, sand, gravel through which groundwater flowsrelatively impermeable layers (rock & clay) keep water contained in aquiferrecharge area - land area that has water percolating downward into the aquifer
24Groundwater Problems Two kinds of problems reduce groundwaters utility:Discharge problemsGroundwater pollutionWithdrawal problemsDepletionLand subsidenceSalt water intrusionGroundwater is very vulnerable to pollution, which is costly and time-consuming to clean up.
Withdrawal problems occur because human pumping can remove water from aquifers much faster than they recharge.
Ogallala Aquiferworlds largest know aquiferirrigation increases yields 2X to 3X central pivot irrigation removes much water from the aquifer
essentially nonrenewable (slow recharge rate)pumped 8-10X times faster than recharge rateexpect 25% reduction by 2020What are solutions?31
34Pollution of ground water is a serious water pollution issue that is largely out of sight. Pollution that seeps into the soil is gone as far as the people that created it are concerned; however, if it moves through that soil it can eventually contaminate groundwater. This polluted groundwater might be the source of drinking, industrial, or irrigation water. This figure shows the many potential sources of groundwater pollution. Note that the source of groundwater pollution, like other types of water pollution, is not necessarily in same place as the source of the polluted water. This is because the water moves laterally underground just as it does above ground. There is a very interesting recycling technique that millions of people in the U.S. practice. When a home relies on a well for its drinking water, it may also rely on an on-site sewage treatment of wastewater. This treated water is likely to be unknowingly recycled. Basically, water used in the home is introduced into the field adjacent to the home. This wastewater leaches through the soil and reaches the water table; then, the water is pumped through the home's well and reutilized by the people living in the home. Protection of ground water quality in Washington State from pollution is one of the state's highest priorities environmentally. Washington State has a policy of no net degradation of groundwater within the state. Water Quality Today
35This figure shows the percent of water quality impaired U.S. rivers in 1998 (U.S. EPA). It's important to notice that in some cases the percentages seem more a function of political boundaries then they are likely of reality, as this information is reported by states voluntarily. According to this data, Washington State is among the least polluted states in the United States. The State of Mississippi is by far the most polluted. It is a known fact that Washington State has suppressed the release of information on mercury contamination in the upper reaches of the Columbia River. Also, there are different standards by which states determine whether water is impaired in quality; however, it's obvious from this figure that water quality impairment is a serious issue in U.S. rivers. Pollution of Water Sourcesturn to neighbor and think of as many kinds of water pollution as possibleIll give you a short time to do this (minute or less)The group with the most, of course, wins36Classes of Water Pollution1. disease-causing agents (pathogens)bacteria (causing dysentery, enteritis)coliform bacteria (Escherischia coli = E. coli)normally live in intestinal tract of animalsindicators of fecal contamination if present in water0 bacteria/100ml water for drinking - WHO recommendation200 bacteria/100ml water for swimming - EPA recommendationviruses infectious hepatitisparasitesprotozoans (Giardia)worms (Schistosomiasis)
37Classes of Water Pollution2. Oxygen-demanding wasteswastes that decompose (organic) by oxygen requiring (aerobic) bacteriathe bacteria thus reduce DO in waterthis impacts all aquatic life - food chain (web)
38Classes of Water Pollution2. Oxygen-demanding wastesBiological Oxygen Demand is the amount of oxygen required for microbial metabolism of organic compounds in waterhigh organic compounds increases BOD, leading to low quality water
microorganisms feed on organic compounds in waterfeeding depletes oxygen in watermore organic compounds = greater feedingreduces oxygen in water greatlylarger organisms with gills have inadequate oxygen to breathrestricts biodiversity in water39Classes of Water Pollution3. water-soluble inorganic chemicalsacids, salts, compounds of toxic metals (mercury & lead)40Classes of Water Pollution4. Inorganic plant nutrientswater-soluble nitrates, phosphatesfrom where do these originate?
41Classes of Water...