Arsenic and groundwater by 2sGRZLZ

VIEWS: 14 PAGES: 23

									What’s in Your Water? Wyoming’s Link to the Global
                   Community
     Developed by: Lekan Ajayi, Scott Carleton, Teresa Strube, and Nancy Van Dyke

Overview
    Water is a crucial resource in the arid west. The quality of our water resources has become
front-page news as we discover areas vulnerable to contamination. Understanding the issue of
water contamination requires coordination between the disciplines of geology, chemistry,
biology and medicine. The issue of water quality is an issue shared by communities around the
world. This unit represents the interdisciplinary nature of real-world problems in science by
focusing in on the issue of arsenic contamination of groundwater resources. Lessons address
important principles of the various disciplines in science within the context of a real-world
problem. . Many lessons apply to several subjects due to the interdisciplinary nature of real-
world science. Lessons explore:
     Where and why arsenic is found naturally in the environment
     How arsenic’s chemistry facilitates its movement from geologic formations to plant and
        animal physiological systems.
     The chemical role arsenic plays in physiological systems
     The observable physiological effects of arsenic poisoning
     How arsenic can be detected in the environment and possibilities for solving
        contamination problems
     The complexities of human-caused versus natural contamination of water resources




                                           Biology




                          Chemistry                         Geology
Subtopics
    Biology: respiration, principles of molecular biology, digestion
    Geology: hydrology, groundwater systems
    Chemistry: redox reactions, adsorption
    Environmental Science

Lessons within the Unit:

1. Groundwater: The Water Beneath our Feet
2. Coal Bed Methane Production: Who Polluted the Water
3. Why Arsenic? The Chemical Personality of an Element
4. Arsenic and Human Health: An Introduction to Toxicology
5. How Safe is Your Water? Water Quality Testing
6. Remediation and Consensus: No Simple Answers



                                Lesson 1
                 Groundwater: The Water Beneath our Feet
                               Developed by Nancy Van Dyke

Grade Level: 7-12                             Estimated Time: 90 minutes
Topics Covered: Hydrology
Standards and Benchmarks: 11.1.7 Geochemical cycles

Goals:
   Student will understand that groundwater plays an important part in the hydrologic cycle
       in the West.
   Students will understand that geology influences our water supply and condition of water

Objectives:
     Students will be able to describe groundwater and its processes and how it relates to the
        larger water cycle
     Students will predict how human-caused changes will alter groundwater patterns
Vocabulary:
Permeability: The capacity of rock or unconsolidated material to transmit a liquid, which is
primarily a function of the sizes of the interconnected pores and shapes of the openings.
Porosity: The proportion of air space compared to solid material in a given substrate
Aquifer (confined and unconfined): An underground unit of soil or rock that can transmit
significant quantities of water to wells. A confined aquifer has layers of impervious rock above
and below it.
Subsurface flow: The movement of water below the surface through permeable rock and soil
materials
Discharge: When water leaves groundwater sources and enters into streams, lakes and rivers or is
pumped up through a well
Recharge: The addition of water to groundwater through infiltration of precipitation through the
unsaturated zone into the aquifer.
Artesian well: A man made spring or well that does not require pumping because of natural
pressure (from a confining layer) on the aquifer
Cone of depression: When the water table is lowered within an aquifer nearby a pumping well.
The slope created can be influenced by the rate of pumping and the aquifer substrate

Materials and Preparation: Large bucket, measuring cups, 2 liter soda bottles or glass
aquariums, straws, gravel, sand, small rocks, felt, other materials as desired to represent geologic
layers and vegetation, food coloring, sponges, water, USGS maps of local aquifers and geologic
formations.

Background Information
        Groundwater makes up a large proportion of the drinking water for communities in the
West. Large fractures and folds in the earth’s crust tend to be recharge areas for aquifers below.
Even without fracturing from faults and folds, sandstone and limestone exhibit porosity (though
to a lesser extent than fractures. Many Wyoming aquifers are built on sedimentary rock
formations; sandstone is more conductive than limestone. Shale tends to be a confining layer.
        Groundwater systems are well modeled through build it yourself kits that come with
aquarium style pumps, reservoirs for water, and clear wells. These are made by ….Groundwater
is also modeled well by filling soda bottles with various materials to simulate substrates with
varying porosity.
        The water supply from aquifers in the arid west is at risk of depletion. If too many
nearby wells attempt to draw from the same aquifer, the water table will be too low to pump
water.

Procedures
Engage
        Students will gather around the large bucket. Teacher will explain that the bucket
represents all the water in the world. Teacher will take out approximately 98% (most!) to
represent ocean water that cannot be drinking water. Most of this remaining freshwater is
unavailable- held in glaciers. About .4% of the initial amount of water is available groundwater
and .02% is available surface water. This would probably be represented in a few tablespoons.
While groundwater is something most of us rely on, there is a limited supply in the world.
        Teacher will ask students to draw a sketch of what they think groundwater looks like and
how it is held in the ground. Then the teacher will have students visualize pouring milk on their
cereal. How much liquid would be in a bowl of cereal? How is milk stored in this bowl of
cereal? This will help students understand the structure of groundwater systems. Is this different
from what people expected?

Explore
       In pairs, students will build models of a groundwater system within a clear plastic 2-liter
soda bottle or a glass aquarium, using the materials provided to them. Students can be directed
to model the aquifer that serves their region or community (maps are often available through
USGS or the local municipality). Try to have one model represent a confined aquifer.
Explain
       Teacher will lead students in demonstrating how substrate affects infiltration and
recharge of an aquifer. What observations can students make about this system?

Elaborate
      Students will make predictions about what could influence the water levels within their
models and informally test those predictions. Why are confined aquifers closed systems?
      If you have access to a groundwater model with a pump, you can demonstrate the
movement of groundwater by adding dyed water to the model.

Evaluate
        Students will further investigate the nearest aquifer used by people in their area. What
geologic formations surround the aquifer? What kinds of minerals are in these rocks? Are there
protection plans in place to conserve or maintain the aquifer? Is your aquifer vulnerable to man-
made pollution? Why or why not?

References
1. Ground Water Primer online:
        (http://www.purdue.edu/dp/envirosoft/groundwater/src/ground.htm)
2. Luna Leopold. 1997. Water, Rivers and Creeks. University Science Books: Sausalito, CA.
3. Moore, J.E., Zaporozec, A., and Mercer, J.W. 1995. Groundwater: A Primer. American
        Geological Institute: Alexandria, VA.
4. National Groundwater Association:
        http://www.ngwa.org/programs/educator/lessonplans/groundwater1.aspx
5. Project WET. 2004. Discover a Watershed: The Missouri.
6. USGS: http://water.usgs.gov/nawqa/trace/pubs/segh1998/
7. Wyoming Agriculture in the Classroom: Teacher Lessons & Activities Guide.
        www.wyoingagclassroom.org

                              Lesson 2
         Coal bed methane production: Who polluted the water?
                      Developed by Nancy Van Dyke and Teresa Strube

Grade Level: 9-12                              Estimated Time: 90 minutes
Topics Covered: Geology, hydrology, environmental studies
Standards and Benchmarks: 11.1.7 Geochemical cycles, 11.1.10 Structure and properties of
matter, 11.3.2

Goals: Students will understand the process of coal-bed methane production and how it relates to
geology

Objectives:

      Students will analyze evidence to determine the potential for contamination from coal-
       bed methane production as well as other environmental impacts
      Students will infer whether possible contamination from coal-bed methane production is
       human-caused or natural
      Students will be able to describe several ways of dealing with contamination from coal-
       bed methane byproducts.

Vocabulary:
Aquifers (confined and unconfined): An underground unit of soil or rock that can transmit
significant quantities of water to wells. A confined aquifer has layers of impervious rock above
and below it
Confining Layer: The layer of impervious substrate laying above and/or below an aquifer. This
causes the confined aquifer to be a system under pressure. The pressure is released when wells
drill through the confining layer.
Discharge: When water leaves groundwater sources and enters into streams, lakes and rivers or is
pumped up through a well
Permeability: The capacity of rock or unconsolidated material to transmit a liquid, which is
primarily a function of the sizes of the interconnected pores and shapes of the openings.
Contamination: Have students try to define this themselves! Contamination can take place
through natural processes as well as human development and action.
Recharge: The addition of water to groundwater through infiltration of precipitation through the
unsaturated zone into the aquifer.
Pressure energy: The energy given to ground water by the weight of overlying water and earth
materials
Remediation: Actions that lead to the removal or improvement of a problem

Materials and Preparation:
   Groundwater models:
          o At least one simulating contaminated coal beds (available models include
             Neo/SCI groundwater exploration model and Envision environmental education
             models)
          o If possible, a model of the local aquifer, often available through City Utilities
   Long narrow pipette, food coloring (a small amount of dye should be injected into the
      coal bed before the demonstration)
   Plastic syringe that fits into wells on groundwater model,
   Sticky notes with vocabulary words,
   Color maps, articles, and pictures for stations (see appendix),
   2 aluminum pans, one with 2 cups tap water (evaporated) and another with 2 cups water
      with ½ cup dissolved salt (evaporated)
   Samples of coal and pyrite ores


Background:
        About 7.5% of natural gas production in the U.S. comes from coal beds several hundred
feet underground. The Powder River Basin in East-Central Wyoming is a rapidly developing
area for coal-bed methane production.
        There are currently about 13,000 wells and it is expected to grow to more than 75,000
wells. The total amount of water produced will be more than 1 million acre-feet of water
        Water is an important by-product of coal bed methane production. A large volume of
water in the thick coal beds keeps pressure on the beds, which keeps methane gas adsorbed to the
coal. In the process of coal bed methane production, wells are drilled and water is removed,
enabling mining operations to capture the released methane gas. Methane, or natural gas, is
growing as an important form of energy. In the Powder River basin in central Wyoming,
significant coal bed methane production occurs from sedimentary rock layers. Little is known
about the quality and characteristics of the water being pumped out from these wells.
        Arsenic can make its way into ground water resources naturally, from the weathering of
rocks. It could also be present from pesticides used in the past (in orchards specifically) or from
glass and electronics industries or mining operations. It is difficult to predict where you will find
arsenic naturally occurring in groundwater because it depends on specific ores present in the
layers. Arsenic tends to bind to iron and sulfur, therefore it is often associated with pyrite rocks.
        When arsenic enters water naturally, it is due to mobilization of arsenic that is found
naturally in ores. In Wyoming, we often find arsenic attached to pyrite. There is still a lot that is
not known about this process. The two main mechanisms are oxidation of the arsenic in the
pyrite and “microbial degradation” of sediments. Oxidation is increased when aquifers are over
pumped. The more toxic arsenite is the form that is MORE mobile in groundwater, and therefore
more likely to move around and find its way into human water supplies. Microbial activity leads
to the reductive dissolution of arsenic-rich iron oxyhydroxide. In short, arsenic often enters
groundwater when sulfide minerals are oxidized. There is a large degree of “spatial variability”
therefore it is very difficult to predict natural contamination.
        Arsenic and other elements and salts can be found at high concentrations in confined
aquifers in arid regions due to the arid nature of the climate combined with a geologic history of
sedimentary rock layers. Water in these formations can be more saline than seawater! Aside
from dissolved salts, water can also contain high concentrations of metalloids. Arsenic (one such
metalloid) can be found naturally at concentrations of 20-30 ppb, higher than the maximum
allowable levels of 10 ppb.
        Contamination could be a problem where a large quantity of water is pumped up and
released in the processes of capturing coal-bad methane. So far, arsenic contamination has not
been a big problem in the holding ponds near coal-bed methane production sites, but the number
of wells will grow substantially in the coming years and there is the possibility of arsenic-laden
pyrite sources to be tapped with future drilling projects.
        Water from coal-bed methane production, contaminated or not, is a significant issue
because it cannot be pumped back into the ground. There is uncertainty concerning the best
option for dealing with this large volume of water.
        The contamination risks posed by cal-bed methane production represent the complexities
of water quality issues. While sometimes contamination is clearly human-caused, unsafe
compounds and minerals are also found naturally and risks can be multiplied by the actions of
human development.

Procedures
Engage
       Teacher will use a groundwater model to review characteristics of aquifers. Have
students place colored sticky notes with vocabulary words onto the front of the model. What else
can they identify on this model? Where would their town/school/home be?
Explore
Point-source contamination
        Students will use model of their local aquifer or a nearby aquifer to look at how
contaminants could enter the water system. Dye applied at ground level will represent leaking
industrial wastes. Students should take notes and make sketches in their research journals or
notebooks. What defines contamination? Teacher can take notes on the board.
Natural contamination
        Teacher use the model of coal beds and associated geologic layers that has been
“contaminated” with a small amount of dye. Teacher will begin pumping water from the
reservoir into the groundwater system. Students will be instructed to pay attention to what is
happening in the system. Teacher will then use the syringe to pump water up from the coal bed,
simulating water and methane released from the coal bed. Students will see that a contaminant
can be found naturally in groundwater aquifers and in the water pumped to the surface. Where
are the confining layers?
        What is happening here? Why is it moving throughout the aquifer? What happens if
arsenic is bound to ores? We can think of the dyed water as a metalloid such as arsenic.
        Ask students how this phenomenon changes their definition of contamination.

Explain
       Students will visit exploration stations in groups to investigate coal bed methane
production (see appendix for resources such as maps, diagrams, pictures and articles).
   1. Students will look at maps of current and proposed development in the Powder River
       Basin. There are currently about 13,000 wells in the Powder River Basin. Development
       is expected to grow up to more than 75,000 wells. Station Question: How could this
       affect the environment and communities near the basin?
   2. Students will use a cross-sectional diagram to learn more about the geology behind coal
       beds. Station Question: If the elevation of the Powder River Basin is about 4900 feet,
       how deep underground are the coal beds where methane is collected? The yellow, green
       and brown layers represent what kind of rock? How could other minerals accumulate in
       these layers?
   3. Students will look at a diagram of a coal bed methane well that shows how methane and
       water reach the top. Station Question: Why is water an unavoidable by-product of coal-
       bed methane production? What are some things that could be found in this water? Could
       the water be pumped back down into the coal bed? Why or Why not?
   4. What do we do with all of this water?
       Students will brainstorm ways that proposed solutions to this water problem are
       influenced by geology and hydrology. Station Question: What are pros and cons to these
       ideas? (Italics refers to possible responses)
            Treat the water in a water treatment plant to remove salts and high levels of
               minerals. (There is no/limited infrastructure in place for water treatment at
               production sites)
            Give water to farmers for irrigation or livestock (Water is high in sodium
               bicarbonate, which swells clays and makes soils “hardpan” when water
               evaporates. It has been proposed to change the chemistry of the water by
               substituting calcium or magnesium for the sodium to prevent the hard pan effect)
             Put water into holding ponds nearby (Water can infiltrate unconfined aquifers and
              perhaps into people’s drinking water supplies)
           Release water into nearby stream beds (Pumped water changes the water
              chemistry of the streams and rivers, can lead to much larger than natural stream
              flow)
   5. What happens to the water? At this station, students will find a pan of water filled with 1
      inch of salty tap water (labeled) and in another identical pan, the same solution, 1 inch
      deep that was put in the pan 7 days previously (labeled). Station Question: What process
      has been demonstrated here? Students will also find two pictures here, one before and
      one after high salinity pump water was applied as irrigation. Station Question: What do
      think could explain the change? How might this change be related to the process
      demonstrated by the two aluminum pans?


Elaborate
        As a group, go over the exploration stations. What answers did students come up with?
What are the big ideas here? Students should sketch the pathway that molecules of arsenic
compounds take to get down into layers of strata near coal beds, starting with molecules on the
surface of the earth in a stream, river or ocean. What is the essential step in the hydrologic cycle
that influences the presence of arsenic on sedimentary rock layers?

Evaluate
        Students will create a Venn Diagram of the similarities and differences between human-
caused and natural contamination of water sources. Where does coal-bed methane production fit
in?
        Students will work in groups of 2 or 3 to write a report on the possible contamination site
at a coal-bed methane drill site to help a gas development company ensure they follow
environmental laws. Report should address the following: Is the contamination most likely due
to natural reasons or human-caused pollution. How are these forms of contamination similar and
different? Is there a way to prevent the arsenic from entering the groundwater?

References
1. Mahimairaja, S., Bolan, N.S., Adrinao, D.C., & B. Robinson. 2005. Arsenic
       contamination and its risk management in complex environmental settings. Advances in
       Agronomy 86. 1-82.
2. Mechenic, C. & Hay, D.R. 1995. Sand Tank Ground Water Flow Model Manual. Dept of
       Biological Systems Engineering, Cooperative Extension. Institute of Agriculture and
       Natural Resources. University of Nebraska, Lincoln.
3. PULSE. Culture & Cycles: Arsenic and Human Health. Available at:
       http://pulse.pharmacy.arizona.edu/9th_grade/culture_cycles/index.html
4. Roth, T.R. 2006. Groundwater and arsenic: A regional assessment of private wells and a novel
       point-of-use removal system. Masters thesis, University of Wyoming.
5. Smedley, P.L. & Kinniburgh, D.G. 2002. A review of the source, behavior and distribution of
       arsenic in natural waters. Applied Geochemistry 17, 517-568. Available at:
       http://www.msal.gov.ar/htm/site/pdf/source,%20behaviour%20and%20distribution.pdf
6. Thyne, Geoffrey. Enhanced Oil Recovery Institute, University of Wyoming, personal
      communication
7. USGS. Water produced with coal-bed methane. USGS Fact Sheet FS-156-00. November
      2000. Available at: http://pubs.usgs.gov/fs/fs-0156-00/fs-0156-00.pdf




                            Lesson 4
      Arsenic and Human Health: An Introduction to Toxicology
                                   Developed by Lekan Ajayi

Grade Level: 10-12                                   Estimated Time: 50 minutes
Topics Covered: toxicology, cellular biology
Standards and Benchmarks: 11.1.1 The cell

Goal: Students will understand that water quality influences human health
Objectives: At the end of this lesson plan, students will understand:
        The meaning of toxicology
        What makes a poison.
        How the chemical properties of arsenic relate to its poisonous effects in humans.
        Symptoms and treatment of arsenic poisoning

Vocabulary

1. Encephalopathy: Fluid accumulation in the brain

2. Adenosine tri phosphate: is a chemical substance that is most important as a "molecular
currency" of intracellular energy transfer.

3. Paraesthesias: Prickling sensations felt most commonly in the arms or legs caused by nerve
damage

4. Toxicology: Branch of science that quantifies the toxic effects of chemicals on living system
such as animals, plants and humans.

Materials and Preparation:
The materials needed for this presentation are as follows:
   1. Laptop computer
   2. Overhead projector
   3. Paper and pencils
   4. 400ml beakers
   5. Food coloring
   6. Radish seeds
   7. Toxicology class worksheet (see appendix)
Background Information:
        Everything in our environment is made of chemical compounds; the food we eat the
water we drink, and even the air we breathe. Life as we know it here on earth can be described as
a sum of chemical reactions, which allow our bodies function as living beings. In recent times,
there has been increasing interest in the study of the harmful effects of chemicals to the very life
processes that they support. This interest has generated a lot of concerns about the risks that
chemicals pose to human health as well as questions into the very nature of these chemicals. For
example, what makes a chemical poisonous? Are toxic chemicals all the same? Are the toxic
chemicals natural or manmade? In an attempt to answer these puzzling questions, we must turn
to a very important branch of science known as toxicology which attempts to quantify the
harmful effects of toxic substances to humans, animals and plants. Toxicology applies important
information from different aspects of science such as biology, chemistry, physiology, and
microbiology to determine the effects of various chemical substances on living systems as well
as the response of these systems to these chemicals.
        The roots of modern toxicology can be traced back to a man known as Paracelsus who
stated that “the dose makes the poison.” This statement forms the basis for the standards of safe
amounts of chemicals present in water or food set by various regulating agencies.
 For example, on the 23rd of January, 2003, the Environmental protection Agency set the
maximum contaminant level of arsenic to 10 parts per billion in the United States. Although this
lesson plan focuses on the toxic effects of arsenic on living systems, the principles employed in
this exercise can be applied to other chemical substances as well.
        Arsenic is a metal that naturally exists abundantly in the earth crust and in small
quantities in water and rocks. About one third of the arsenic in the atmosphere comes from
natural sources, such as volcanoes, and the rest comes from man-made sources. Natural
geological contamination can cause high levels of arsenic to be found in water obtained from
drilling wells. This is particularly true of countries such as Bangladesh whose population suffers
immensely from arsenic poisoning. Industrial processes such as coal mining, timber preservation
and agricultural use of pesticides can introduce arsenic into water and air. Furthermore, it is
worthy to note that animals can ingest arsenic and accumulate them in their bodies which serve
as a source of poisoning to other animals that are higher in the food chain.
Arsenic exists in two forms: Arsenate and arsenite, with arsenite being the more toxic of the two.
Arsenic can also exist in both organic and non organic forms. Organic forms of arsenic are found
in sea food and are normally harmless in humans but may interfere with laboratory testing for
arsenic poisoning.
        Humans are mostly exposed to arsenic poisoning through food and water. Food by far
seems to be the greatest source of exposure to humans, except in countries such as India and
Bangladesh where there are high levels of naturally occurring arsenic in water. The damage done
by arsenic as with other poisons to humans depends on a number of factors namely: the physical
form of the arsenic ingested, whether powder or pellets, the route through which the arsenic
entered the body, whether by ingestion or inhalation, the type of arsenic ingested and the amount
ingested. All forms of arsenic are usually corrosive to the gastrointestinal tract and affect cellular
metabolism in adverse ways. Furthermore, arsenic has been known to alter cell membranes, thus
causing cancers in humans. Finally, Arsenic affects the nervous system over prolonged periods
of exposure, causing, numbness and tingling in hands and feet, accumulation of fluid in the brain
which could lead to headaches.
       Arsenic contamination is a global issue (U.S., Argentina, Chile, India, China, Mexico,
Taiwan, Thailand). Arsenic contamination (levels >10 mg/L) in the U.S. is more common than
we thought previously.

Procedures
Engage
        Students will be engaged by assessing any previous knowledge or misconceptions about
what a chemical is. It is a common misconception for students to associate chemicals with toxic
man made substances such as insecticides, detergents and so on. It is the goal of this discussion
to provide students with the knowledge that chemicals are all around us, and that the most useful
and necessary substances that our lives depend on such as food and water are chemical
compounds. It would be important to define what a chemical is and have students make a list of
chemicals that they know and classify them as natural or manmade. Students will also be
engaged by assessing their knowledge of what makes a chemical toxic. It would be important to
start by asking them if the most useful chemical substances such as water could be toxic. By
starting with useful chemical substances, students will hopefully discover a pattern that all
chemicals could be toxic depending on how much of the chemical is ingested. This is one of the
fundamental principles of Toxicology. Students will also be engaged by filling out a worksheet
provided to them. The worksheet should contain questions that cover the main topics (enduring
ideas) addressed in the lesson plans. Finally students will be assessed on their knowledge of
arsenic why they think it could be an important poison.

Explore
       Exploring the fundamental principles of toxicology in this lesson plan would be done by
performing a series of activities. The first activity performed would be a demonstration of how
the amount of a substance can make it toxic. For more information refer to the activity sheet. It
would be important to liken the human body to a giant beaker filled with water as the human
body is composed of 75% water. In addition to that, it would also be important to relate the
smaller beaker to the importance of human weight and size in poisoning.

Explain
      Explanations given to students in class should cover the following topics:

               1. A convenient way to start the class would be to introduce students to science
                  of toxicology. What is toxicology and why is it important? It is important to
                  let students know that toxicology incorporates other aspects of science such as
                  chemistry, biology and physiology into determining the toxic effects of
                  chemicals on living systems. The importance of the amount of a substance in
                  determining its toxicity when ingested. As mentioned earlier, start with
                  important chemical substances like water and allow the students to draw their
                  inferences by providing adequate examples. It would be helpful to explain the
                  different mechanisms though which chemicals exert their toxicities. For
                  example water intoxication is often caused by the dilution of important
                  electrolytes in the body such as sodium which is primarily responsible for the
                  regulation of fluids. This causes cells in the body to swell up to the point of
     bursting. On the other hand, an overdose of a drug such as Tylenol causes
     liver damage by elevating enzymes in the liver.
2.   After establishing the dose toxicity relationship, it is important to elaborate on
     a few properties of chemicals that might contribute to their potencies as
     poisons. For example chemicals ingested in powdered form tend to be more
     dangerous than those ingested in pellet forms. This is because powdered forms
     of chemicals tend to be more easily absorbed by the digestive system. Also,
     other properties such as the size of the molecules, and charge matter in
     determining the toxicities of compounds. For example, arsenic as an element
     easily crosses to the central nervous system because it is not easily ionized
     causing fluid accumulation in the brain.
3.   After explaining these important principles of toxicology, the platform for the
     discussion of Arsenic as a poison would have been established. It would be
     helpful to give a brief history of arsenic, explaining how it has been the poison
     of choice in the middle ages. The position of arsenic in the periodic table
     should be discussed and it should be also noted that arsenic shares the same
     group with phosphorus, meaning that they possess similar chemical
     properties. This is of particular importance because Arsenic substitutes for
     phosphorus in ATP leading to decreased energy for cellular metabolism in
     biological systems. The two types of arsenic, arsenate and arsenite should be
     discussed and the difference between them explained. It is important to note
     that arsenite tends to be more toxic than arsenate due to its valence electrons.
4.   There are two types of arsenic poisoning: Acute and chronic. The difference
     between these should be elaborated. Acute is caused by a large amount of
     arsenic ingestion over a short period of time while chronic arsenic poisoning
     is caused by small amounts of arsenic ingested over a long period of time.
     Chronic arsenic poisoning is more common than acute and is the type of
     poisoning that exists in some parts of the world such as India and Bangladesh
     where the drinking water is contaminated with arsenic.
5.   The symptoms of arsenic poisoning should be discussed. It would be helpful
     to divide by organ systems. The main organ systems involved in arsenic
     poisoning are: the digestive system, nervous system, cardiovascular system.
     Arsenic is corrosive to the digestive system, causes capillary beds to leak,
     causing heart problems, crosses into the brain causing fluid accumulation in
     the brain which in turn leads to symptoms such as confusion, altered mental
     states. Arsenic also causes nerves in the arms and legs to die leading to
     prickling sensations in the limbs. Finally, it is worthy of note that arsenic
     causes changes in the structures of cells by binding to DNA which makes it
     carcinogenic. Acute poisoning of arsenic normally presents with corrosion of
     the gastro intestinal tract while chronic arsenic poisoning presents with a
     range of symptoms and is more difficult to diagnose.
6.   How Arsenic is detected and treated. It is important to note that only acute
     arsenic poisoning can be treated. It is essential to explain why this is the case
     to students. Acute arsenic poisoning is more easily treated because it often
     detected within a short period of time from when the ingestion occurred,
     making it easier to flush out before it gets the chance to filter into the blood.
                   Chronic arsenic poisoning on the other hand, is more difficult to treat because
                   arsenic would have filtered into the body systems which makes it more
                   difficult to detect and remove.

Elaborate
Activitiy 1: “The dose makes the poison……”

This activity is a demonstration of the relationship between the dose and toxicity of chemical
substances. Divide students into groups of fours. Each group should be provided with a three
250 ml about ¾ full with water. Each group will place one drop of food coloring in the first
beaker, five in the second, and ten in the last beaker. Each beaker should be stirred and the
resulting changes in color should be discussed in relation to the dose toxicity relationships of
chemicals. Each group should use white paper as a backdrop for easy visualization. It would be
helpful to liken the human body to a giant beaker since the human body consists mainly of water.

Activity 2: Size matters…..

Fill one 400mL and one 100mL beaker about ¾ full with water. The large beaker represents an
adult and a child is represented by the small beaker. Put the same amount of food coloring in
each beaker (1 or 2 drops). The small beaker will be darker than the larger one. Use white paper
as a backdrop for easy visualization. This is a demonstration on the importance of size or weight
of the organism/human. Children may be more severely affected than an adult by the same dose.
This provides the basis for why lethal doses of poisons are often measured in relation to human
weight.

Evaluate
        Students will be evaluated based on a number of exercises. Students will be given a
worksheet at the beginning of the class. The worksheet will contain questions that address the
main topics to be covered during the lesson. Students will be required to answer the questions as
the lesson progresses. The worksheet would be turned in to the teacher for assessment at the end
of the lesson. When performing the activities designated in this lesson plan, students will be
required to document their observations on the student observation sheet attached to this lesson.
Students will answer the questions and turn their papers to the teacher for grading. Finally, at the
end of class a list of answers would be provided to students and the students would be required to
match these answers with questions.

References


   1. http://www.nlm.nih.gov/medlineplus/arsenic.html

   2. http://apps.caes.uga.edu/sbof/main/lessonPlan/IntroToToxicology.pdf

   3. http://www.niehs.nih.gov/health/scied/teachers/curricular.cfm
   4. http://www2.envmed.rochester.edu/envmed/EHSC/outreach/downloadcurriculum13
      1206.html

   5. Ontko A.C, PHCY 6312 : Introduction to Clinical Toxicology, 2007; fa



                                Lesson 5
              How Safe is Your Water? Water Quality Testing
      Developed by Teresa Strube, Nancy Van Dyke, Lekan Ajayi, and Scott Carleton

Grade Level: 7-12                              Estimated Time: 90 minutes
Topics Covered: Chemistry, Geology
Standards and Benchmarks: 11.1.10 Structure and properties of matter, 11.1.11 Chemical
reactions, 11.2.2, 11.2.5, 11.3.2

Goal: Students will understand how water quality is tested and how conclusions are drawn.
Objectives:
   Students will analyze several samples of water using the full scientific method
   Students will review their knowledge of arsenic and its geologic context

Materials and Preparation: Hach Test Kit, arsenic-laced water or real water samples from
wells in the area (clearly, getting a hold of arsenic is not often possible, but if you are near to
Laramie, you can connect with someone at the University who can help you), gloves, full
protective goggles, aprons, Handouts for work stations about arsenic contamination around the
globe (Ajo, Arizona: http://earthonly.com/ajo/water/index.php, Bangladesh: http://www-
tc.iaea.org/tcweb/publications/factsheets/arsenic_contamination.pdf, Japan:
http://phys4.harvard.edu/%7Ewilson/arsenic/countries/japan/arsenic_project_japan.html, Inner
Mongolia:
http://phys4.harvard.edu/%7Ewilson/arsenic/countries/inner_mongolia/inner_mongolia.html)

Background Information:
        Arsenic is found as several chemical “species”. Arsenite (As(III)) is more toxic and
mobile, arsenate (As(V)) is relatively less toxic. These are inorganic arsenic compounds. The
organic forms found in fish are much less toxic. Reduction/oxidation reactions are an important
aspect of the chemistry of these compounds. In oxidation reactions, arsenite converts to
arsenate, and in reduction reactions arsenate converts to arsenite. Reduction in aquatic
environments is most likely to occur at pH 6-6.7. Arsenic in any of these compounds will be
measured through the test kits on the market
        Water is tested, especially near human development, to make sure it meets EPA
standards. In the past decade, the maximum allowable levels of arsenic changed from .05 mg/L
(50 ppb) to .01 mg/L (ppb). Sampling of groundwater in the field is done through pump or bailer
wells. When testing for arsenic, sample must be filtered in the field and sealed; if it makes
contact with the atmosphere, arsenic will leave along with iron oxides.
        Studies published through the USGS looking at quality of coal bed methane water in
areas in Wyoming show low levels of arsenic from the wells tested (<0.2 to 2.6 g/L). While
arsenic is associated with rock types common near our networks of coal beds, it remains to be
seen whether this is a significant risk. On the other hand, arsenic is a real and relevant problem
in some communities in Wyoming. For example, Centennial, Wyoming has levels of arsenic in
its well water that are higher than the new, stricter standard for arsenic.
        There are many countries throughout the world that are dealing with significant water
quality problems due to naturally-occurring arsenic. The websites listed above in the Materials
and Preparation section will provide information about how water quality issues have been
studied and how problems are being dealt with in various places around the globe. Printing off
materials and maps and providing them at stations around your lab will give students something
to do while they wait for the test to finish (there is at least 30 minutes of wait time).

Procedures
Engage
        Students will receive a letter addressed to the students from a fictitious environmental
consulting firm or gas development company. The letter requests the help of the students in
testing various water samples for the presence of arsenic in order for the stakeholders to know if
they are jeopardizing surface water quality according to the EPA guidelines with water brought
to the surface through coal bed methane production. What is the research question here?

Explore
        Teacher will bring out various water samples that look alike. Have students brainstorm
questions important in learning about the quality of this water and hypothesize how the samples
may be the same or different. Provide a geologic background for the areas near the wells were
water was collected. Students will create hypotheses and predictions. Class will agree on a
consistent procedure for the testing. Why is it important to be consistent?

Explain
       Students will carry out water testing in small groups using a test kit for arsenic. It is
important to follow all directions in the test kit and to use the proper protective equipment,
Students will collect all data and record it in appropriate data tables.

Elaborate
        During the wait time of about 30 minutes near the end of the arsenic test, teacher can
have students move in groups to various “stations” around the room. Each station will address a
different place in the world where arsenic is causing significant problems for communities and
nations.

Evaluate
         Students will each take on a different role of someone who uses water sampling
information in their career (DEQ agency person, scientist with USGS, graduate student, etc.).
Discussion: How might these experts use or interpret this data differently? What does our data
mean? Students may need to do some research online to learn more about their role. What
conclusions that can be drawn form our data? Should remediation action be taken? Should
restrictions be placed on how the water is used?
                              Lesson 6
          Remediation and Consensus: Real-world Complexities
                                 Developed by Nancy Van Dyke

Grade Level: 9-12                                Estimated Time: 90 minutes
Topics Covered: Chemistry, Biology, Hydrology/Geology
Standards and Benchmarks: 11.2.4, 11.3.1, 11.3.2

Goals:
   Students will understand that many disciplines of science are interconnected and are all
       involved in addressing issues of water quality.
   Students will understand that arsenic and other contaminants can enter water resources
       through natural geologic processes or from human action.
Objectives:
   Students will be able to describe various ways that have been proposed to solve arsenic
       contamination problems, and their advantages and disadvantages

Materials and Preparation: Articles, maps and resources from the websites listed below, or
local newspaper articles concerning an issue not described below
Background Information:
    There are many local and regional contamination issues that have required problem-solving
over the past few decades. These scientific problems are often very complex and involve diverse
stakeholders.
    Relevant examples of water contamination in and around Wyoming:
    1. Atlantic Richfield Arco mine, Milltown, Montana
                This issue is based around the old Anaconda copper, zinc and silver mine. The
                historic mining operation is near the recharge area for an aquifer and the reservoir
                for the city of Missoula. A “plume” of contamination resulted from tailings from
                the mine. For resources, see http://www.cfrtac.org/sitehistory.php,
                http://www.epa.gov/region08/superfund/pdfs/ClarkForkRProposedPlanFactsheet.
                pdf
    2. Union Pacific Tie Treatment Plant, Laramie
                The site of this plant was once a superfund site. The company was required to
                pump, clean and return water to the land. The Laramie River was re-channelized
                in 1985. Another part of remediation was encircling the area with a soil-bentonite
                wall. For resources, see appendix,
                http://www.laramieboomerang.com/news/archivemore.asp?StoryID=105078
    3. Middle green river Basin, Kendrick Reclamation Project area - selenium buildup from
                irrigation. For resources, see
                http://wwwrcamnl.wr.usgs.gov/Selenium/Irrigation.htm,
                http://pubs.usgs.gov/fs/fs-031-03/
    4. Coal Bed Methane Production, Powder River Basin, Wyoming. For resources, see
                http://pubs.usgs.gov/fs/fs-0156-00/fs-0156-00.pdf
When soil and water near the surface is contaminated, there are several ways of removing
contaminants:
Soil capping: Covering a contaminated site with a layer of clean soil
Phyto/bio remediation: Using plants or naturally occurring bacteria to break down contaminants
and remove them from a substrate. If plants are used, they are disposed of carefully since they
have accumulated some contaminants.
Soil rinsing: This is an expensive technique that involved removing the topsoil and literally
washing it with hot water, sometimes mixed with a surfactant.
Immobilization: certain amendments can hasten natural biogeochemical processes that convert
high levels of contaminants into inaccessible forms. One example is bacteria that methylate
arsenic compounds, making them inaccessible to most other organisms, therefore keeping them
from being a significant risk.

       When water in deep aquifers is contaminated, often the only way to deal with it is to treat
the water once it gets to the surface.

Water purification techniques include:
Filtration: When particulate arsenic compounds are removed. Some common filters include sand
filters and porous ceramic filters. More technologically advanced filters use anion-exchange
mechanisms to remove arsenic from water.
Adsorption: Water is run through certain compounds that can adsorb arsenic. Iron oxides
adsorbs arsenic strongly. Other compounds include activated alumina and iron coated sand.
Simple devices can be made with an iron salt and activated charcoal.
Precipitation: Arsenic can often be precipitated out of solution with iron and aluminum
compounds and them filtered from the water.


Procedures
Engage
        Provide small groups of students with a shallow tray of a moist sand and soil mixture.
Add ¼ cup or so of water dyed with food coloring. Have each group brainstorm ways to clean
up this soil. Connect to the techniques described above in Background Information. How might
remediation be different if the contaminated substrate was a few hundred feet under the ground?

Explore
        Exploration stations: Have students explore stations set up around the room that provide
resources concerning various contamination issues in the region. Have students take notes on
what the contamination issue is and how people have decided to solve the problem. What are the
steps in remediation?

Explain
       Teacher can go over each of the stations, asking for student input. Do students have the
same basic understanding of the problems?
Elaborate
       Group discussion: Is contamination natural or man-made? How does this influence the
possible ways that contamination could be remediated?
Evaluate
       Have students research another water quality issue in their region and write up an
analysis of the problem and proposed solutions. How does science play a role? What are the
complexities?

References

1. Crossey, M.J. 1990. Movement, distribution, and effects of organic groundwater
       contaminants in the Laramie River, Wyoming, adjacent to a wood-treating plant. PhD
       Dissertation, University of Wyoming.

2. Mahimairaja, S., Bolan, N.S., Adrinao, D.C., & B. Robinson. 2005. Arsenic
       contamination and its risk management in complex environmental settings. Advances in
       Agronomy 86. 1-82.

3. Rice, C.A., Ellis, M.S., and Bullock, J.H. 2000. Water co-produced with coal-bed methane in
        the Powder River Basin, Wyoming: Preliminary compositional data. Available at:
        http://pubs.usgs.gov/of/2000/ofr-00-372/index.html#Contents
4. USGS. Water Produced with Coal-bed Methane. USGS Fact Sheet FS-156-00. November
        2000
Appendix

Lesson 2 Exploration Station Resources
1.
2.




3.
5.
                   Agricultural Application

                                                              Chemistry of CBM Water can Dama
                                                              Soil Amendments May Allow Wate


                                  Qu ic kTime ™ a nd a
                        TIFF (Unco mpres sed ) d eco mpres sor
                           are n eed ed to se e th is pi cture.



                                                                            Year 3
          Year 1




Soil damage due to
high Na content Of
CBM Water
Lesson
Toxicology Class worksheet:


   1. What is Toxicology?




   2. What makes a poison?




   3. Name 2 properties of chemicals that might affect their toxicity



   4. What is ATP?




   5. Why does arsenic substitute for phosphorus easily in biological systems?




   6. What are the two types of arsenic?




   7. Name a 3 symptoms of arsenic poisoning




   8. What is the difference between acute and chronic poisoning?

								
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