Science experiments
SIMULATION OF A POPULATION STUDY
Number 2. REPEATED MARK-RECAPTURE
In this lab exercise we will investigate the use of more than two trappings, to obtain a more accurate population estimate. This will require a little more data collection, and a different formula for calculation. This method is called, repeated marking and recapture.
POPULATION ESTIMATE BY RANDOM SAMPLING
When studying a population, it is usually impossible to count every member of the population. One way to estimate the size of a population is by collecting data by random samples. This method works well when estimating a population of plants in a large field. In this lab, you will calculate a population estimate using random sampling, then compare your estimate to the actual population count.
MEASURING TREE HEIGHT USING A RATIO
Many times we do studies in the field that require us to record the height of the trees. This is a simple way to accomplish this using representative lengths on a meter stick, and the ratio from them.
LIMNOLOGY STUDIES
CONSTRUCTING A BATHYMETRIC MAP OF A POND OR SMALL LAKE
Most limnological phenomena, distribution of biota, and productivity are directly related to the morphological features of the water basin. While many aspects of a lakes fauna and flora can be studied without this knowledge, to venture into theoretical limnology and to determine some indices of productivity, morphometric data must be known.
- Mapping of the water basin should be the centerpiece of any comprehensive study of a pond. Calculations made from the map will allow the investigator to accumulate and relate a lot of data concerning the pond system.
- The purpose of this project information is to help the environmental science student organize an extended project. This is a direct measurement method, intended for a smaller body of water.
DIATOM DIVERSITY
Diatoms (single-celled algae) have frequently been used to evaluate the impact of domestic sewage or industrial waste on the aquatic environment. Use of these organisms in pollution impact evaluation is justified by reason of their sensitivity to pollutants. In a non-polluted environment there will usually be a very high diversity of kinds of different diatoms, while a polluted environment will show a very low diversity with only a few different kinds of diatoms.
- In this investigation, you will collect samples, digest the organic material leaving the silicone shells, and calculate the diatom diversity index (DDI).
ESTIMATION OF PRIMARY PRODUCTIVITY AND RESPIRATION IN A POND
Light and Dark Bottle Method
In aquatic ecosystems, producers and primary consumers are largely microscopic plankton suspended in the water. By measuring the rates of oxygen production and of oxygen consumption in a known volume of water, estimates of the rate of gross photosynthetic productivity, net productivity, and respiration rate can be calculated.
Using the Light and Dark Bottle Method, samples of water are placed in two glass bottles of the same volume. One bottle is left clear, and the other bottle is covered to exclude light. The initial O2 concentrations are measured, then the two bottles are returned to the light conditions from which they were taken for 24 hours. After 24 hours, the bottles are retrieved, and the final O2 concentrations are measured.
ECOSYSTEMS
MEASURING NET PRIMARY PRODUCTIVITY OF GRASS
Laboratory Investigation
The gross primary productivity (GPP) of an ecosystem is the rate at which energy is captured during photosynthesis. Thus, GPP is the total amount of photosynthetic energy captured in a given period of time. We know that plants must respire to provide energy for their life processes, which uses some of the energy of photosynthesis. The energy that remains in plant tissues after respiration has occurred is called net primary productivity (NPP). NPP is therefore the amount of biomass found in excess of that broken down by a plant's cell respiration. NPP represents the rate at which this organic matter is actually incorporated into plant tissues to produce growth.
Only the energy represented by NPP is available for consumers, and of that energy only a small portion is actually used by them. We can express both GPP and NPP as energy per unit area per unit time, or in terms of dry mass per unit area per unit time.
In this lab you will measure net primary productivity for sample plots of different grass species, and compare their productivity. This lab requires approximately 3 weeks total time for plant growth, and 5 separate one-hour lab days.
TESTING FOR TOXIC SUBSTANCES
TESTING CERAMIC DISHES FOR LEAD
Over the years, lead has been used as an additive in ceramic ware, paint, solder for plumbing, glass, and many other materials. As we began to understand just how dangerous lead was in human tissue, its use has drastically dropped. Some of the effects are miscarriages, kidney failer, slowing of nerve conduction, anemia, and inhibition of enzyme action. The glaze on ceramic dishes is no longer allowed to contain led. The problem is that many older dishes are still being used, and even new dishes containing lead may be imported from other countries.
In this lab, you will test for the presence of lead leaching from ceramic ware. In selecting objects to be tested, older glazed items made before 1971 such as cups and bowls are likely suspects for lead. Also imported items, and brightly colored, worn down, or scratched items.
You will prepare standards by quantitative methods, and use them as a comparison to the tests on the objects to get an estimated lead concentration.
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Environmental Science & Ecology