A Primer for Ecocolumns

Transcription

1 A Primer for Ecocolumns Building Ecocolumns meets the following standards: College Board Topic Outline for AP Environmental Science I. Earth Systems and Resources (10 15%) D. Soil and Soil Dynamics (Rock cycle; formation; composition; physical and chemical properties; main s II. The Living World (10 15%) A. Ecosystem Structure (Biological populations and communities; ecological niches; interactions among species; keystone species; species diversity and edge effects; major terrestrial and aquatic biomes) B. Energy Flow (Photosynthesis and cellular respiration; food webs and trophic levels; ecological pyramids) E. Natural Biogeochemical Cycles (Carbon, nitrogen, phosphorus, sulfur, water, conservation of matter), soil types; erosion and other soil problems; soil conservation) VI. Pollution (25 30%) 3. Water pollution (Types; sources, causes, and effects; cultural eutrophication; groundwater pollution; maintaining water quality; water purification; sewage treatment/septic systems; Clean Water Act and other relevant laws) NGSS Science and Engineering Practice #2: Developing and using models Modeling in 9 12 builds on K 8 experiences and progresses to using, synthesizing, and developing models to predict and show relationships among variables between systems and their components in the natural and designed worlds. Develop a complex model that allows for manipulation and testing of a proposed process or system. Develop and/or use a model (including mathematical and computational) to generate data to support explanations, predict phenomena, analyze systems, and/or solve problems.

2 NGSS Science and Engineering Practice #3: Planning and Carrying Out Investigations Planning and carrying out investigations in 9-12 builds on K-8 experiences and progresses to include investigations that provide evidence for and test conceptual, mathematical, physical, and empirical models. Plan an investigation or test a design individually and collaboratively to produce data to serve as the basis for evidence as part of building and revising models, supporting explanations for phenomena, or testing solutions to problems. NGSS Science and Engineering Practice #4: Analyzing and Interpreting Data Analyzing data in 9 12 builds on K 8 experiences and progresses to introducing more detailed statistical analysis, the comparison of data sets for consistency, and the use of models to generate and analyze data. Analyze data using tools, technologies, and/or models (e.g., computational, mathematical) in order to make valid and reliable scientific claims or determine an optimal design solution. Consider limitations of data analysis (e.g., measurement error, sample selection) when analyzing and interpreting data. Analyze data to identify design features or characteristics of the components of a proposed process or system to optimize it relative to criteria for succes NGSS Cross-Cutting Concepts #2: Cause and Effect Mechanism and explanation. Events have causes, sometimes simple, sometimes multifaceted. A major

3 activity of science is investigating and explaining causal relationships and the mechanisms by which they are mediated. Such mechanisms can then be tested across given contexts and used to predict and explain events in new contexts. NGSS Cross-Cutting Concepts #4: Systems and System Models Defining the system under study specifying its boundaries and making explicit a model of that system provides tools for understanding and testing ideas that are applicable throughout science and engineering. NGSS Cross-Cutting Concepts #7: Stability and Change For natural and built systems alike, conditions of stability and determinants of rates of change or evolution of a system are critical elements of study.

4 CCSS Writing 1 Write arguments to support claims in an analysis of substantive topics or texts using valid reasoning and relevant and sufficient evidence. CCSS Speaking and Listening 1 Prepare for and participate effectively in a range of conversations and collaborations with diverse partners, building on others ideas and expressing their own clearly and persuasively CCSS Math Practice 3 Construct viable arguments and critique the reasoning of others.

5 CCSS Math Practice 4 Model with Mathematics CCSS Math Practice 5 Use appropriate tools strategically Instructional Notes the science behind Ecocolumns These notes should be given before going into lab. Can be written on the board or a PowerPoint. Students should copy down notes in a lab notebook or on their data spreadsheets and use as reference for two assessments: Ecocolumns check for Understanding Ecocolumn Data Analysis Questions Building the column with bottles (Day 1) The terrestrial chamber mimics land specifically top soil. The filter chamber cleans the water as it drips from the terrestrial chamber to the aquatic chamber. This mimics nature where sand and gravel clean water from pollutants. This also

6 mimics water treatment plants where we run river/lake/ground water through sand and gravel to capture pollutants. Tertiary wastewater treatment also uses sand and gravel. The aquatic chamber mimics a pond We put gravel under the sand to help with drainage. This is something you should do whenever you plant in pots. The top tray (sprinkler) is used to gently water your seeds and seedlings and will be discarded when the plants grow high enough to touch the bottom. We cut flaps at the top of the aquatic chamber to allow for air flow. This air flow will allow oxygen from the air to dissolve into the water. Building the terrestrial chamber (Day 2) We are planting beans to demonstrate one part of the nitrogen cycle. Nitrogen fixation occurs on the roots of legumes. Nitrogen-fixing bacteria on the roots of legumes turn nitrogen from the air into a usable form for the plants. We are planting other seeds which will use the nutrients in the soil. Legumes add it and also use it. Our soil will begin with nutrients (NPK= other micronutrients) and we will watch to see what happens to the fertility (nutrient level) over time. Flushing the ecocolumn (daily for 2 weeks until you assemble the aquatic chamber) We flush the ecocolumn every day for 2 weeks, because silt and suspended particles will clog the gills of a fish. This dirty water is known as its turbidity. This flushing, however, will leach nutrients out of the soil. So we will add nutrients in other ways. Adding Detritivores (after 1 week) We add worms and other insects as detritivores to help break down decomposing matter into nutrients (NPK). Worms also help aerate the soil (create tubes for water and air flow). Do not add herbivores (Caterpillars, grasshoppers) as they will eat all your plants. Also, do not add crickets as they climb and escape. We add leaf litter (crumpled up leaves) and add to the surface of the soil for these reasons: o Provide food for detritivores o Provide hiding places for detritivores o They will decompose and add nutrients to the soil o Help prevent water loss in the soil by covering the soil and capturing and condensing any evaporated water. Assembling the Aquatic Chamber (after 2 weeks) We start with distilled or spring water so we can control what we add and see how it affects water quality. Dissolved oxygen is important for aquatic life such as fish or snails. Without dissolved oxygen, they will not survive. They usually start dying off at about 2 mg/l. You want your levels to be above 3 mg/l to be on the safe side.

7 ph is important for aquatic life as species have a preferred ph range (usually around 7) and cannot survive above or below that range. A change in ph in a pond, lake or stream could indicate a water pollutant, acid rain, etc. Temperature is important for water in nature as certain species prefer a specific temperature range. If the temperature changes, they will leave or die. Temperature also influences dissolved oxygen rates. Colder water holds more dissolved oxygen (a physical property of water). We will have all room temperature water, because our ecocolumns are indoors. You will not see a change in temperature, but you will measure anyway, to get it in your brains that temperature is an important water quality indicator. We measure nitrites/nitrates initially and will find the levels will be zero, because we are starting with distilled or purified spring water. Over the weeks, your fish will poop and the nitrate levels will increase. We are adding elodea, because the elodea will do the following: o Add dissolved oxygen to the water through photosynthesis o Take in ammonia and nitrates from fish waste which helps keep those levels below toxic levels for the fish o Provide food for the fish o Elodea is wet with water from the fish store and my aquarium. This water is full of nitrifying bacteria which will colonize your aquatic chamber. Adding fish (2-3 days later) Over the past 2-3 days, nitrifying bacteria has colonized your aquatic chamber. This bacteria turns ammonia from fish waste into nitrites and then nitrates. Your fish will poop ammonia which is toxic to itself. The bacteria will turn it into nitrates which is much less toxic. Fish can handle fairly high levels of nitrates. You need to limit your fish to about 1 inch of fish (1 medium or 2 small fish), because the fish will now use the dissolved oxygen and you don t want to run out or the fish will die. Your ph and dissolved oxygen levels may have changed after adding elodea, because the elodea adds dissolved oxygen through photosynthesis and the plant matter may slightly affect ph. Next reading (3-4 days later) Your nitrate levels should go up due to fish waste in your aquatic chamber. As long as you have healthy nitrifying bacteria in the water, it will readily turn ammonia into nitrite and then nitrate. Therefore you will have no or almost no nitrites. Begin to water your terrestrial chamber with aquatic chamber water. Your plants will love this as it contains nitrates and phosphates from fish waste DEAD FISH A decomposing fish will decrease the dissolved oxygen. Bacteria decomposing the fish use the DO in the water so you must remove it and bury it in your terrestrial chamber. The decomposing fish will also add nutrients (N and P) to the soil which the plants will love.

8 Before you get a new fish, you must wait a week or so or until your DO levels return to about 4 mg/l Subsequent readings Carbon cycle in ecocolumns: Producers provide oxygen and glucose (C 6 H 12 O 6 ) through photosynthesis and Consumers eat the glucose and provide plants with CO 2 through cellular respiration. Also, carbon is cycling through decomposition and animal waste and absorbed by producers. Water cycle in ecocolumns: Plants do transpiration Plants also allow seepage Leaching: Leaching occurs as water takes nutrients out of soil. Nutrients in our soil are leaching into the filter chamber. We replace nutrients through the action of detritivores, nitrogen fixation on the roots of legumes and dead fish. Plant height: Plants may spike in growth rate if you buried a dead fish. Plant growth may also slow down as roots run out of space in the terrestrial chamber. Elodea length: Elodea may increase due to the addition of fish waste which has N and P for growth. But, a particularly hungry fish may decrease its size. Some elodea just dies and decomposes and we don t know the reason. Gross Primary Production: The plants and elodea convert energy from the sun (Gross Primary Production) into sugars which are stored in their plant tissues (Net Primary Productivity). GPP-respiration = NPP. Consumers eat the plants to obtain this energy. Temperature: Temperature readings outside help a gardener or farmer know when to plant. Each plant has temperature range for germination and transplanting. ph: Different plants prefer different phs. The majority of plants prefer Bacterial decomposition works best at this range along with nutrient uptake. ph 5 and below are extremely acid and 10 and above are extremely alkaline. Excessive acidity in the soil causes calcium, phosphorus and magnesium to be changed into forms that plants cannot use, causing them to suffer a deficiency. Slowdown of beneficial bacteria also. Increased toxicity from trace elements like aluminum. Strong alkalinity dissolves and disperses humus A farmer can change the ph or grow plants for the ph he/she has in the soil.