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The Chemical, Geological and Environmental Necessity
of Water Conservation in the Albuquerque Region
Dolores Salazar
Introduction
A recent review of the Albuquerque Public Schools science curriculum indicates that several Earth science competencies are not being met. Therefore, the objective of this curriculum unit is to enhance my current Chemistry in the Community (ChemCom) curriculum. A brief overview of geologic Earth processes and local geology in relation to Albuquerque’s water supply will be included, while maintaining basic chemistry principles and concepts.
Unless we experience drought or flooding, we rarely give water a second thought. For many of us, water is as reliable as the rising sun. We turn on our faucet and water flows. We rarely ask the basic questions. What is water? Who uses water? Where does water come from? Why is water considered a precious resource?
The same is true about our local geology. We look to the east, certain the Sandia Mountains will be there when we awake. To our west, we see the volcanoes, confident they are inactive. Between the two our precious Rio Grande. Below us a large but limited water supply. What happened so many years ago to give us these beautiful landscapes?
The ChemCom curriculum attempts to enhance science literacy through a high school chemistry course that emphasizes chemistry’s impact on society. All ChemCom units focus on a chemistry-related issue currently facing our society and our world. The first ChemCom unit is on water. The unit introduces basic chemistry concepts, while discussing the water issues facing a fictional town. I would like to enhance my current curriculum by providing an overview of Earth formation and chemical composition, along with providing data specific to Albuquerque with an emphasis on conservation. I estimate the unit to be complete in 3 to 4 weeks.
Topics:
Objective:
Upon completion of this unit, students should have a general awareness or basic understanding of:
Earth Formation and Age
Scientists believe that all energy and matter was created with the birth of the universe, in what is known as "The Big Bang Theory." According to the "Big Bang Theory" an unimaginably large cosmic explosion occurred 10 to 20 billion years ago. The cosmic explosion resulted in hot pure energy. As this hot pure energy cooled, the first subatomic particles of matter were formed, subsequently enabling the creation of the first elements. 1
Universe
The new universe, age of 3 minutes, contained 75% hydrogen and 25% helium. As the universe continued to expand over the next hundreds of millions of years, the hydrogen and helium cooled and condensed into galaxies of stars, including our sun. The planets are a by-product of the formation of these stars. The heavier elements in the universe were later created by nuclear fusion within the stars.2
Solar System
Our solar system developed from a nebula. A nebula consists of clouds of dust and gas
remains from initial star formation.3 During this formation the Earth formed
from matter that coalesced into a single planet. The age of the Earth is 4.6 billion
years. Scientists have determined this using radiometric dating (measurement of
radioactive decay) of meteorites and analysis of isotopes in Earth materials. As early
Earth formed, it heated up to 2000 0C (3632 0F). 4 The
heat allowed dense elements to sink to the center of the earth, while light elements
floated toward the surface
Earth Composition
The Earth is characterized by the following three distinct "regions:" (1) the atmosphere, (2) hydrosphere, and (3) lithosphere.
Atmosphere
The atmosphere is the gas that surrounds the body of the planet. It has an average thickness of 100-km (60 mi.). The atmosphere consists of nitrogen (78%), oxygen (21%), argon (0.9%) and trace amounts of helium, neon, nitrous oxide, methane and ozone. Variable amounts of water vapor and carbon dioxide can also be detected in the atmosphere.5
Hydrosphere
The hydrosphere covers 71% of the Earth’s surface. The hydrosphere includes all bodies of water, including the oceans, inland seas, lakes, rivers and underground waters. The hydrosphere also includes water in glaciers and water in the atmosphere. The hydrosphere consists of water, sodium chloride-salt (3.5%) and smaller amounts of magnesium, sulfur, calcium and other elemental ions. Its average thickness is 5 km (8 mi.).6 The average depth of the oceans is 3794 m (12,447 ft.), yet its mass is only 1/4400 of the total mass of the earth.7
The hydrosphere began forming 4 billion years ago during a period of global melting. Chemical compounds and light elements such as water, carbon dioxide, nitrogen, hydrogen, and some oxygen, dissolved in magma moving upward from the upper mantle. Gravity prevented many of these elements from escaping into space. However, hydrogen easily escaped to space because it was too light to be held by gravity. Because oxygen is so chemically reactive it quickly formed compounds with various elements (including hydrogen) until oxygen, produced by oxygen producing microbes allowed build up in the atmosphere to current levels. As the Earth continued to cool, the water vapor condensed and began filling the ocean basins. The amount of water on Earth has remained more or less constant since its release from the atmosphere 4 billion years ago.8
It is obvious that most of the earth’s water supply is stored in the oceans (97%). However what is surprising is the amount of water stored elsewhere. Glaciers and ice caps store just over 2% of the Earth’s water. Groundwater, our primary source of water (in Albuquerque) represents only 0.62% of the Earth’s water. Lakes contain 0.009% of the Earth’s water supply, while atmospheric moisture and rivers account for a mere 0.001% and 0.0001 % respectively.9
The amount of water on Earth has remained nearly constant for billions of years due in
part to the hydrologic cycle (water cycle). The hydrologic cycle is a continuous
circulation of water between the Earth’s atmosphere and crust. 10 ( The
City of Albuquerque-Public Works Department provides a useful classroom poster
illustrating Albuquerque’s water cycle in terms of transpiration, percolation, runoff
and evaporation.)
Lithosphere
The Lithosphere includes the crust and upper-mantle, which are divided into 13 tectonic plates. The middle mantle, lower mantle and the core lie below the lithosphere. The crust has an average thickness of 40 km (25 mi.).11 Rocks found in the crust are almost entirely made up of 11 elements. The most abundant is oxygen (46.6%), followed by silicon (27.72%), aluminum (8.13%), iron (5%), calcium (3.63%), sodium (2.83%), potassium (2.59%), magnesium (2.09%), and titanium, hydrogen, and phosphorus (totaling less than 1%). Several other trace elements can be found in amounts of 0.1% to 0.02%. These elements include; carbon, manganese, sulfur, barium chlorine, chromium, fluorine, zirconium, nickel, strontium, vanadium, and precious metals such as gold and silver. These elements are rarely found in their free state. Instead they are usually combined in various combinations to form compounds in the crystalline state known as minerals.12
The dense mantle extends from the base of the crust (40 km/25mi) to a depth of 2900 km (1800 mi.).13 It consists of iron and magnesium, silicon and oxygen. The mantle is solid except for a zone between 70 km (44 mi.) and 200 km (125 mi.) known as the asthenosphere consisting of weak "soft" rock.14
The core extends from the base of the mantle (2900km/1800mi) to the Earth’s center 6400km (4000 mi.).15 It is composed of a liquid outer core and a solid inner core consisting of iron and nickel. The temperature in the core is estimated to be as high as 6650 0C (12,000 0F).16
Plate Tectonics
In 1912, a German meteorologist, Alfred Wegener, proposed the first theory of continental drift. Through observation Wegener realized present day continents resembled pieces of a "jig saw" puzzle. He therefore concluded that continents drifted apart from a single supercontinent he called "Pangaea." Wegener was able to find a match between fossils on the coast of South America and the coast of Africa even though the Atlantic Ocean separates both continents. However, scientists could not explain how or why the continents drifted. In the 1960’s the idea of continental drift was finally accepted when scientists discovered that the Earth’s lithosphere is broken into plates and interior forces allow the plates to move along the Earth’s surface.17 The lithospheric plates are composed of light colored continental granite and a dark oceanic basalt rock. The oceanic rock is generally thinner and denser than continental rock.18
About 250 million years ago, during a period of widespread crustal unrest, a supercontinent (Pangaea) formed by aggregation of pre-existing continental fragments. The existing continents are the drifting fragments of this supercontinent, produced by the break-up of Pangaea that started over 200 million years ago. The theory of Plate tectonics describes the evolution of the earth in terms of the movement and interaction of 13 semi-rigid lithospheric plates that are constantly moving toward, away from, and past each other.19 The weak "soft" rock of the asthenosphere and the convection within the mantle enable the plates of these continents to drift across the Earth’s surface. The boundaries of these plates are zones where tectonic activity such as earthquakes, volcanism and other processes are favored. Plate tectonic processes also affect global climate and climate change.20
The North American lithospheric plate has been moving westward for at least 66 million
years. It appears that this plate is very slowly separating along the famous Rio Grande
Rift. Million of years from now an ocean may eventually separate the North American plate.21
Albuquerque’s Geology: A Brief Look
Albuquerque’s unique geology is the result of a series of distinct changes in the Earth over millions of years. One of the oldest features in Albuquerque is the granite found in nearby mountains. Sandia granite was formed 1.5 billion years ago when hot liquid rock (magma) was injected into existing bedrock deep below the earth’s surface. After the formation of Sandia granite, (not the Sandia mountains), very little is known about the local geology. A long period of erosion flattened the landscape and erased more than 1 billion years of geologic history. This time period is called "The Great Unconformity." 22
"The Great Unconformity" ended 300 million years ago with most of New Mexico covered by shallow seaways. Many marine creatures found a home near shore waters. These remains are embedded into sediments on the ocean floor. A lime deposit over the Sandia granite hardened and became well layered.23
The shallow seas retreated and evaporated 250 million years ago allowing reptiles (dinosaurs included) and some early mammals to find a home on the floodplains and near-shore marshes.24
Between 70 and 90 million years ago, three major events occurred. North America broke away from Europe and started to drift westward. Then a second sea briefly covered parts of New Mexico, bringing with it more swamps and life forms. Finally, the "Age of Reptiles" ended; as many as 75% of all life forms became extinct. Some scientists believe an asteroid or several asteroids collided with Earth. Dust from the collision may have partially or totally blocked sunlight from reaching the Earth for several years. As a result, the Earth cooled, plants died from lack of sun and rain, and animals died because of a lack of a food supply.25
The Rio Grande Rift began forming about 25 million years ago. The rift was formed when fractures due to tension and stretching caused a large block of Earth crust to down-drop. As the down-drop occurred the land on both sides began to rise. The Sandia Mountains, composed of granite and limestone that formed 300 million years ago, are a result of this uplifting. Some of the same layers of limestone that can be found atop the Sandia crest (10,000 ft above sea level) lie buried below the city at a depth of 15,000 ft below sea level (5 miles total). The Rio Grande Rift extends more than 600 miles from Mexico to Colorado. Albuquerque lies in the center of this North –South rift, one of the few continental rifts worldwide. The western edge of the rift lies along the Rio Puerco and the eastern edge lies at the base of the Sandia Mountains (approx. 30 miles wide). The rift remains active as it continues to grow and possibly separate the North American Plate millions of years from now.26
About 190,000 years ago a fault line (fracture) within the rift developed. Hot liquid magma made its way to the surface to form the five north-south volcanoes on the city’s west side.27
The Rio Grande first flowed into closed basins along the rift, as the basins filled with rock debris, rivers and streams joined until the Rio Grande became a through flowing river between 2 and 5 million years ago.28 It is only within the last 100,000 years that the Rio Grande entered the valley following the rift line. The Rift valley was slowly filled with thousands of feet of porous sediment. With time, rain, and river water, a very large underground reservoir formed, which would one day supply the water needs of a growing city--Albuquerque.29
The Rio Grande is a shallow river that travels a distance of 1878 miles from the Rocky
Mountains to the Gulf of Mexico. In North America it is second in length to the
Mississippi/Missouri combination.
Albuquerque’s Water Supply
It has been projected that by the year 2000 nearly all states west of the Mississippi River will experience a water shortage. 30 The city of Albuquerque currently relies on groundwater in the local aquifer to meet the water needs of the area. Groundwater has been described as excess surface water that percolates through the earth’s crust because of gravity and the porous nature of soil, rock and sediment.31
An aquifer is a rock or sediment structure that is porous, permeable and contains water. The Albuquerque Basin aquifer consists of a "deep" and "shallow" aquifer stored in an alluvial basin within the Rio Grande Rift. The aquifer consists of mostly sand and gravel, which was deposited millions of years ago in the geologic formation known as "The Upper Santa Fe Group".32 The aquifer extends from Cochiti to Socorro (north-south) and Tijeras Canyon to the Rio Puerco (east-west).
There is a thin (60-80 ft) shallow aquifer zone located just below the Rio Grande floodplain. It is composed of sand and gravel combined with silt and clay in some areas.33 This water is not of high quality and is not currently used by the city.
The deep aquifer has a rugged topography with as much as 15,000 feet of relief forming deep basins, mountain ridges and gaps. It consists of five major depressions, each containing sub-basins, which in turn crisscross with other geologic features (i.e. faults, flexures, benches, grabens and prongs) that affect water flow.34
Water from the deep aquifer provides such a natural high quality water to the city of Albuquerque that it requires only minimal treatment. Chlorine is added to the water to prevent the growth of microbiological organisms. In 1983 residents voted to add fluorine to the water supply as a dental protection measure. Unfortunately there are naturally occurring contaminants in Albuquerque’s water, however all are currently below the federal standards. If federal standards change, treatment may be required.
The aquifer does not contain as much water as it was once believed. In 1993 the United States Geologic Survey released a study concluding that the water level in portions of the aquifer had declined 160 ft since 1960.
Recharge is the refilling of the aquifer. The rate of recharge is affected by the large amount of water pumped from the aquifer. The addition of riverside drains and canals along with changes in agriculture have also had an effect on recharge rate.35 Mountain front recharge (melting of snow), Rio Grande River recharge, percolation due to precipitation and canal seepage are currently recharging the aquifer.
Natural recharge occurs very slowly and does not replace water as fast as it is being pumped out. It is possible, however, to use injection wells near recharge windows/corridors to help increase the rate of recharge. Recharge windows/corridors are permeable areas on or near the surface that have a high potential for rapid recharge of the aquifer. Albuquerque has several of these areas along the base of the Sandia Mountains.36
The City of Albuquerque operates 93 wells, which are distributed over 200 square miles
and provides water to over 470,000 residents. These wells can pump over 300 million
gallons of water per day. Albuquerque also has 44 storage tanks, which can hold 206
million gallons of water.37 Unfortunately we live with a limited water supply.
In hope of ensuring a "sustainable water supply" the City has established "Albuquerque’s Resource Strategy." Mayor Jim Baca stated "One of Albuquerque’s most critical challenges is the provision of a sustainable water supply. The City is meeting this challenge on three fronts: implementation of the Albuquerque/Bernalillo County Groundwater Protection Plan; implementation of an aggressive water conservation program; and working toward optimizing both our surface and ground water by using San Juan/Chama surface water for drinking water and by reclaiming and reusing industrial wastewater."38
In 1994 the City of Albuquerque adopted the first component of the Water Resource Strategy, the Groundwater Protection Policy and Action Plan. The goal is to protect groundwater by finding and cleaning contaminated groundwater and promoting responsible use of groundwater.
In 1995 the City Council launched one of the nations most comprehensive water conservation programs. The goal of the program is a city wide 30% reduction in water use per person in 10 years (by 2005). The residential community uses 71% of Albuquerque’s water, followed by the Commercial (17%), Institutional (9%) and Industrial (3%) sectors of the city.39 From 1987 to 1994 the average per capita water use in Albuquerque was 250 gallons per capita per day (gpcd) – one of the highest in the Southwest (Tucson-155; Santa Fe-160; El Paso-175; Phoenix-220 gpcd).40 The cost of water remains one of the lowest in the Southwest at $0.86 per unit (1unit equals100 cubic feet or 748 gallons).
The City has maintained a strong water conservation campaign with the slogan "Reduce Your Use Save Our Water". A few of the conservation measures include:
In 1998 the average per capita water use for Albuquerque was down to 213 gpcd. These conservation measures have resulted in a savings of 28 billion gallons of water thus far.41
In 1997 the City adopted the third component of the Water Resource Strategy. The project is designed to eliminate our dependence on the groundwater supply by combining groundwater and river water to: 42
Physical Properties of Water
What is water? Water is a polar molecular compound composed of two hydrogen atoms and
one oxygen atom (H2O). The hydrogen and oxygen atoms are held together by a
covalent bond in which the electrons are unequally shared. Water has several unique
physical properties. A physical property is a property, which can be observed or measured
without changing the chemical composition of the substance.
Density
Density is the ratio of mass and volume in a given substance. Gases are less dense than liquids. The solid form of a substance is usually denser than its liquid form; the exception to this statement is water. Solid water (ice) at 0 0C has a density of 0.9167 g/ml, while liquid water at 4 0C has a density of 1.000 g/ml. As water freezes it expands, contrary to the behavior of most liquids, which contract, thereby increasing its volume and decreasing its density. As a result solid ice floats on liquid water. This unique property is important to aquatic life in rivers and lakes. Imagine the consequence of solid ice sinking in liquid water. 43
Surface Tension
Water has a high surface tension compared to other liquids. Surface tension is the inward force, which tends to minimize the surface area of all liquids. Surface tension tends to hold drops of liquid in a spherical shape. The greater the surface tension the more spherical a drop will be. It is the high surface tension of water that allows some insects to "walk" on water. The downward force of gravity on the insect is less than the force of attraction between water molecules. The surface tension of water can be decreased by adding a wetting agent (such as soap) to interfere with the strong intermolecular attraction (hydrogen-bonding) between water molecules.44
Specific Heat
Water has a high specific heat or heat capacity. Specific heat measures the ability of a substance to store heat energy. Specific heat is the amount of heat need to raise the temperature of 1 gram of a substance by 1 0C. The specific heat of water is 1.00 cal/g0C whereas the specific heat of iron is 0.107 cal/g 0C. To increase the temperature of iron by 10C, only 1/10 as much heat is needed compared to the amount needed to raise the temperature of water. On a warm day water absorbs heat from the environment, lowering the air temperature. On a cool night heat is transferred from the water to its cooler environment, raising the air temperature.45
Solvent
Water has often been described as the universal solvent. Since many substances can
dissolve in water, chemically pure water does not exist in nature. A solution is a
combination of a solute and a solvent. A solute is the dissolved substance. A solvent is
the substance doing the dissolving. In a salt-water solution, salt is the solute
(dissolves) and water is the solvent (does the dissolving). Solutions in which water is
the solvent are called aqueous solutions. 46 Unfortunately many substances can
dissolve in water, thus the quality of groundwater is compromised.
Suggested Activities/Assessment
Purpose: Give students a visual understanding of geologic time and their place in it.
Use a long piece of butcher paper to create a timeline in the classroom. Attach paper to a wall and separate it into 5 equal sections, each representing 1 billion years, further subdivide each section into millions of years. Use a geologic time scale to plot key geologic events.
Purpose: Give students the opportunity to recreate Pangaea and relate it to the current location of the continents
Provide students with pictures of the continents and the continental shelves from an Earth Science (geology) textbook. Have students cut all pieces then attach the continents onto the appropriate continental shelves. Students can now arrange the continental "jigsaw puzzle" so all pieces fit together.
Purpose: Give students insight to the interior of the Earth
Have students draw and label the regions and sub-regions of the Earth including thickness, chemical composition, and physical state.
Purpose: Allow students to visualize the condensation of water vapor and relate it to the filling of ocean basins.
Set up a distillation apparatus. Allow students to observe the distillation process and explain the condensation process.
Purpose: Give students the opportunity to really look at Albuquerque’s landscape and relate it to the geologic past.
Show students the Sandia Mountains and West Side Volcanoes and discuss the geologic significance. If it is not possible to take students to each site, find a location at the school, which provides the best view. The Rio Grande Nature Center would make an excellent field trip to discuss the importance of the Rio Grande.
Purpose: Help students become aware of their water use habits.
Have students list all of their actions and activities from the time they awoke until the time they entered the classroom. As soon as the list is complete have students identify all the activities and actions that required the direct use of water.
Bonus: Have students write a short scenario of how their day may have been different if they had woken up and the "well was dry"
Purpose: Help students relate their personal/family water use with the local and national average.
Have students record all the water used in their home over a three-day period, then calculate the average water used per person in their home. Have students graph their average and the average of their classmates and then calculate a class average. Compare and discuss their personal average water use to the class, local and national averages. Were these days typical of any other day? What factors should be considered when looking at average water use?
Have students use their family water bill to calculate the average number of gallons of water used per day. Students with personal wells should seek out a relative or friend and ask to borrow their water bill. (For student who cannot get a water bill or forget to bring one, a sample water bill will be provided.) After calculating the daily average, compare average to the average over their three-day period.
Purpose: Help students realize that water issues are "real-life" issues and concerns.
After reading the articles students should be able to identify the issue, the relevant chemical facts, any proposed or hypothesized solutions and political implications. Have students write a reaction paper to the article or perhaps use topics as possible debate issues.
Purpose: To assess student understanding of Albuquerque’s water supply
Have students prepare a water conservation pamphlet for the school/community.
11. Physical properties of water.
Purpose: Help students relate the
importance of water’s physical properties to the environment.
Density: Have students determine the density of water and compare it to the density of other substances. What if the density of ice was higher than the density of liquid water? What effect would it have on aquatic life?
Solubility: Have students test the solubility of various substances (solids and liquids) in water. Why is water called the universal solvent? How does water’s solubility effect the environment in terms of groundwater?
Specific heat (high for water)
Have students compare the specific heat of water to other substances.
Why must water give off lots of heat in order to freeze? Why does the high specific heat of water makes the climate warmer in the winter and cooler in the summer near large bodies of water?
End Notes
Bibliography
Albuquerque: City of Contrasts Committee. Albuquerque: City of Contrasts-Albuquerque’s Environmental Story. 1988.
Albuquerque’s Environmental Story-Albuquerque’s Natural Environment. http://www.cabq.gov/aes/s1geol.html
Albuquerque’s Environmental Story –Water. http://www.cabq.gov/aes
American Chemical Society. Chemistry in the Community. Dubuque: Kendall-Hunt, 1988.
Chronic, Halka. Roadside Geology of New Mexico. Missoula: Mountain Press, 1986.
City of Albuquerque-Water Conservation Annual Report 1998.
City of Albuquerque-Reduce Your Use Save Our Water. Pamphlet
City of Albuquerque-Welcome to the Desert. Pamphlet
Merrits, Dorothy, et al. Environmental Geology. New York: Freeman and Co, 1998.
Microsoft ® Encarta ® 97 Encyclopedia © 1993-1996 Microsoft Corp.
Molles, Manuel C.,Jr., Ecology: Concepts and Applications. Boston: McGraw-Hill. 1999.
Permian Period, Microsoft ® Encarta ® 97 Encyclopedia © 1993-1996 Microsoft Corp.
Plummer, Charles C., and David McGeary. Physical Geology. Dubuque: WC Brown, 1988.
US Bureau of Reclamation. Middle Rio Grande Water Assessment-Citizen Summary. 1997.
Wilbraham, Anthony C., et al. Chemistry. Menlo Park: Addison-Wesley, 1987.
Teacher Bibliography
Albuquerque’s Environmental Story-Albuquerque’s Natural Environment. http://www.cabq.gov/aes/s1geol.html This web site provides a brief overview of Albuquerque’s geologic events.
Albuquerque’s Environmental Story –Water. http://www.cabq.gov/aesl. This web site provides information regarding Albuquerque’s water supply.
Chronic, Halka. Roadside Geology of New Mexico. Missoula: Mountain Press, 1986.General geologic terms are discussed in relation to New Mexico Geology.
City of Albuquerque Public Works Department (5th floor in City Hall) has a variety of educational resources (coloring books, posters, videos etc.)
City of Albuquerque-Water Conservation Annual Report 1998. A summary of Albuquerque’s efforts and results of water conservation.
Wilbraham, Anthony C., et al. Chemistry. Menlo Park: Addison-Wesley, 1987. A high school textbook with general chemistry information.
Student Bibliography
Albuquerque’s Environmental Story-Albuquerque’s Natural Environment. http://www.cabq.gov/aes/s1geol.html
This web site provides a brief overview of Albuquerque’s geologic events.
Albuquerque’s Environmental Story –Water. http://www.cab.gov/aes/s5water.html. This web site provides information regarding Albuquerque’s water supply.
American Chemical Society. Chemistry in the Community. Dubuque: Kendall-Hunt, 1988. A high school textbook which provides easy to read general chemistry information.
Chronic, Halka. Roadside Geology of New Mexico. Missoula: Mountain Press, 1986. General geologic terms are discussed in relation to New Mexico Geology.
Slow the Flow-City of Albuquerque Public Works Department. A high school
guide to conserving and protecting Albuquerque’s water.