Patricia Dung, UCLA Science Project Co-Director

The Urban Physical Environment- Secondary

Introduction:
What is here?
An ecosystem is comprised not only of living things, the biotic part of an environment, but also of the physical environment, the abiotic part of the environment. Some of the abiotic factors include the water, air, weather, and geological features found in a given area.

What makes up the physical environment of the city? How were the hills, valleys, and flatlands formed? How does the physical environment change with time? How does the physical environment influence the living things that are found in the city? How do the living things influence the physical environment?

Work in small groups. Select a study area on your school campus, nearby vacant lot, or park. If possible, the area should contain some "volunteer plants" (weeds) and bare ground, as well as paving and/or lawn.

Materials: (for each group)
-thermometers -sling psychrometer -pH paper -liquid detergent -turbidity kit	-ozone badges -string & sticks -collecting bottles -index cards -magnifier/hand lens	-meter stick or tape measure -petroleum jelly (vaseline) -soup can/soil sampling tube -tapwater Tour/Water Test Kit -soil test kit

Urban Safari Tasks:

A. Microclimates

Air Temperature

Make a sketch of your study area indicating the green areas, paving, and buildings on a grid representing aquare meters. Make several temperature readings 1 meter above the surface and record your data in oCelsius on the map where you made the reading. Be sure to make readings above any of the following, if found in your study area:

open barren ground or soil:
open concrete, asphalt, or cement:
open grass or weeds:
open shrubbery:
open puddle, pool, fountain, or pond:
under the shade of a tree:
shade of a building:

How do temperature readings on the sunny side of a building compare with the shady side of buildings?

How does the air temperature at the top of a building compare with the ground level?

How does the temperature on the surface of the soil compare with the temperature 4" under the surface?

Look for areas on your map that have the same temperature. Connect these areas with a curved line on your grid map to show areas of "isotherms".

How do your readings compare over the grid map? Is there any pattern?

What effect do plants have on the microclimate?

What effect do the built structures ( streets, sidewalks, buildings) have on the microclimate?

Cities are sometimes characterized as "urban heat islands". Why do you think that might be?

What are the different rates of heating and cooling of various building materials, such as styrofoam, adobe, aluminum, plaster, glass, etc.?

How does the air temperature differ in various rooms of a house/building facing different directions?

Relative Humidity

Relative humidity is the water vapor in the air at a given temperature compared with the maximum amount of water vapor that the air could hold at that temperature. It is a ratio expressed as a percentage. The relative humidity can be measured by comparing a wet bulb thermometer reading with a dry bulb thermometer reading. Read the instruction sheet with the sling psychometer and determine the relative humidity in the following places of your study area.

	dry bulb oC	wet bulb oC	rel. humidity
open barren ground:	________	________	________
open grassy area:	________	________	________
open puddle or pond:	________	________	________
under the shade of a tree:	________	________	________

What is the relationship between the air (dry bulb) temperature and the relative humidity?

What differences in temperature and relative humidity would an insect crawling on the ground experience compared to one flying 3 meters in the air?

How do plants affect the amount of moisture in the air? Why? How does standing or moving water affect the amount of moisture in the air?

Does cloud height in the city vary with the relative humidity?

Wind

How do the wind speeds vary near buildings, around fountains, downstairs, in the sun or in the shade?

How do urban canyons (narrow areas/passages between big, tall buildings) vary the wind speed?

B. Air Quality

Option One: Number your index cards 1-4. Spread one side of four index cards or pieces of acetate with a thin layer of petroleum jelly (clear contact paper can be used). Place cards 1 and 2 with the sticky sides up on open ground in two different places (one near a busy street or road); place the others within the foliage of trees (secure with paper clip). For best results, place the cards out at the start of your study and retrieve them at the end of your study.

Compare the dust particles that have been trapped on the cards. You can use your hand lens to observe the particles.

Which card contained the least particles? Which had the most? Why? Do trees cleanse the air? How?

Option Two:
If available, wear an "ecobadge" after arriving at your study site. Use the color chart to determine the parts per million of ozone exposure for one hour of exposure (the top opening) Compare with the other sites.

Locations: ________________ After One Hour ______________p/mil.

Health Risk of Air Quality: ________________

Do you think ozone concentrations are greater in cities or in rural areas? Why?

C. Soil

1. Litter and top soil collection: Collect samples of the litter ( loose organic material on the surface of the soil) and top soil. Place these in labeled zip-lock bags to take back to the classroom.

Back in the classroom, take a pH reading of the soil in the zip-lock bags. ( if the soil is not moist, remove a teaspoonful of it and add drops of distilled water.

_________pH of top soil.

Empty the contents of the zip-lock bags on a sheet of white paper and examine with a hand lens or dissecting scope. Note any parts of plants, insects, and other organic matter (dark). What kind of crystals and inorganic matter can you discern?

A quick way to assay the soil is to note the color of your sample. A dark or black soil is high in humus (decomposed organic matter). A light color denotes sand. The color of clay is in between.

_________color of soil.

Weigh a small sample of soil from your bag.

_________weight of soil in g.

Let your soil sample dry over several days (can be dried in an oven) and reweigh the contents of the sample.

Difference in weight in drying Original weight of soil

x 100 = percent moisture in soil

Weigh a small sample of your dried soil and place in a crucible. Heat over a bunsen burner until the humus turns to ash. Weigh again.

Difference in weight in burning Original weight of dry soil

x 100 = percent humus in soil

2. Core sample:

Option One- Use a soup can with two open ends. Twist one open end into soft soil. Dig the soil away from one side and slip a piece of cardboard underneath. Wrap the ends of the can securely with aluminum foil and rubber bands.

Option Two - Use a soil sampling tube.

Remove the soil in the sampling tube or soup can carefully by pushing a stick or plunger into the opposite end. It is okay if the soil core doesn't hold together. Drag the contents of the soil across a sheet of white paper so that the layers of soil, if any, are still separated. Examine with a hand lens. How many different layers can you observe? How does each differ from the other in color, particle size, components, etc.? Draw a profile of your core to show the various layers.

Add your soil sample to a tall container of water. Shake vigorously and let settle. Note the comparative thickness of each layer and its percentage of the total sample.

____________% clay ___________% silt ___________% sand

Refer to the composition charts above. What is the soil type or combination type of your sample?

3. Soil Chemistry: Using the soil test kits you can test samples of soil for potassium, nitrogen, iron, pH, etc.

How does the chemistry of soil samples in gardens differ from soil found in unplanted areas?

How does the soil chemistry vary near a busy thoroughfare vs. a quiet street?

D. Water Quality

Collect samples of water from various places, such as a drinking fountain, water fountain, puddle, pond/lake/stream, faucet, bottled water. (If you are given this assignment ahead of time, you may collect water in various parts of Los Angeles. Be sure to include well water as well as aqueduct water.)

1.Turbidity: Turbidity is the amount of muddiness or cloudiness of the water.

Option One: Use the La Motte Turbidity Test Kit to test your samples of water. This test will not work unless the water is fairly turbid.

Option Two: Shine a strong light (like from a slide projector) through your water samples. Use a light meter to detect the amount of light absorbed by the turbidity of the water. ( You may use a spectrophotometer if your school has this equipment.)

2. Water Hardness:

Option One: Fill each water bottle 1/4 full. Add a drop of diluted liquid deterngent to each of your sample bottles. Shake each bottle for one minute and compare with a drop added to distilled water. Observe the amount of suds or bubbles after shaking and after standing for five minutes. (You may need to add more detergent to some samples, count the number of drops it takes to produce suds.)

Option Two: Use hardness test tablets in Tapwater Tour.

Does "hard" or "soft" water produce more suds?

What is the amount of phosphate in the liquid detergent? What is the relationship between the amount of phosphates and the amount of suds? How do phosphates in detergents affect lakes and streams?

3. pH and Chemical Tests: Use pH paper (or phenol red or cabbage juice) and Tapwater Tour/ Chemical Tests for chlorine, copper, and iron. (Chlorine can be tested with tablets, strips, or indicators sold where swimming pool supplies are sold.)

How does water from wells differ from aqueduct water?

How does the water from the faucet which has sat in pipes all night compare in iron and copper content to water that was collected after letting the water run for a few minutes?

How does water from bodies of water (ponds, lakes, streams, etc.) compare with tap water?

How does water from an aquarium compare with tap water?

How does bottled water compare with tap water?