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Exploring bioremediation, how plants can help clean water |
OBJECTIVES:
· Constructed wetlands · Natural wetlands · Bioremediation MATERIALS: · tule· cattail · Hand lens · soil (two types, one should be hydric) ELECTRONIC MATERIALS: · Wetland in the City · worksheet BACKGROUND:
Tyson
Lagoon was expanded to increase storm water capacity
and enhance the natural habitat of this area.
The Public Works Agency of the County of Alameda has created three
ponds (constructed wetlands) which are referred to as Tule Ponds.
Wetlands are among the most productive ecosystems in the world.
A fresh water marsh is as productive as a tropical rain forest.
Wetland plants are specialized because they can withstand water
levels that most land plants cannot.
Bacteria, protozoa, and fungi are bountiful as decomposition of
organic matter releases nutrients.
These microscopic critters are eaten by larger invertebrates like
arthropods and mollusks, that in turn are eaten by amphibians, reptiles
and fish.
During
a storm event, water will flow from asphalt, cement, and saturated soil.
Sediments, chemicals, and trash within the watershed, will be mixed
with the water. Ponds B and C use narrow connections to help retard
the flow of objects that float, like oil and garbage. Motor oil coats fish
gills, preventing the fish to use dissolved oxygen in the water.
You can notice that the constrictions between the ponds help to
narrow the flow and trap these lighter objects.
Pond A
is designed to slow the flow of water,
which allows suspended particles to drop out of the water column.
This increases the water quality of the water and is less of a potential
hazard when it enters the San Francisco Bay. The suspended particles
can include heavy metals like copper (Cu), lead (Pb), and zinc (Zn), as
well as simple particles like
sediment and soil. Tules help
to remove them from the water.
Residential and urban growth in a watershed increases water runoff. When you construct a home, industry or road, water is then prevented from percolating downwards into the ground and flows into a series of pipes. If you look at the beginning of Pond A you will see a large pipe which is bringing run-off from the surrounding community into this stormwater detention system. Water quality is frequently enhanced as water passes through wetlands. Plants help to slow the flow of water and cause sediment to settle out. Aquatic plants like algae or diatoms together with large emergent plants like tules and cattails, add dissolved oxygen in the water during photosynthesis. Dissolved oxygen is used by fish and other aquatic organisms. Cattails and tules also provide shelter for larger animals living in the pond. Bioremediation is a waste management technique that involves the use of organisms to remove or neutralize pollutants from a contaminated site.
PROCEDURE: 1. Discuss that Tule Ponds at Tyson Lagoon was created to clean stormwater before it goes into the San Francisco Bay.2. Read Wetland in the City, which goes over how the area was created (based on a real engineer who designed it) 3. Discuss with students some of contaminants in storm water.
Explain the difference between hydric and non-hydric soil.
A
hydric soil is a soil that is saturated, flooded, or ponded long enough
during the growing season to develop anaerobic conditions in the upper
part of the soil.In organic wetland soils (hydric), a thick organic layer
develops over time where microbial decomposition is severely slowed or
remains incomplete under waterlogged conditions.
Water quality is frequently enhanced as water passes through wetland.
Plants help to slow the flow of surface run off and cause sediment
to settle out. Living aquatic
plants like algae and large emergent plants like tules and cattails, add
dissolved oxygen to water during photosynthesis.
Wetland plants support much of the life in open water, and plants
like cattails and tules provide shelter for larger animals living in the
pond.
6.
Next, have them compare the
plant samples tule and cattails--both water plants that help filter water.
Students can peel
the surface of the plant samples so they can see the structures
inside. The air compartments
are especially clear in the tule plants.
These structures make the plants buoyant in water.
Native Americans made their boats out of tule reeds.
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