Temperature and Oxygen Profiles
Temperature and O2 vs. Depth
The rate of dissolved oxygen in the Anderson Pond is a vital indicator of the overall quality of the water. Oxygen is used by organisms for respiration and by bacteria to break down organic compounds. A higher level of oxygen indicates a lower amount of organic material present to break down, and thus a higher quality of water. The amount of oxygen, however, can also be influenced by natural factors such as temperature, turbulence, amount of suspended material, amount of respiration by organisms, and the amount of photosynthesis. The A.P. Environmental Science and Freshwater Ecology classes took samples of water from different depths of Anderson Pond with a Van Dorn bottle to examine the relationship between O2 and temperature with increasing depth. Temperature was examined to determine whether or not the pond showed any thermal stratification, a summer phenomenom in most temperature lakes. Thermal stratification can effectively isolate the top and bottom portions of the water column from mixing with each other, and, in a eutrophic waterway such as Anderson Pond, enhance the depletion of O2 from the lower levels of the water column due to respiration and decomposition.
In general, while temperature consistently decreases with depth, the pond shows no strong thermal stratification. Late summer and early fall are the times of the year when the temperature profile indicates the possibility of weak stratification. This weak trend is most likely due to both the depth of the pond and the role of the artificial stream in mixing the pond water. Water is pumped from the bottom and released on top. This circulation would prevent any permanent stratification pattern from fully developing.
Our data also shows that O2 levels are low in Anderson Pond, especially at deeper depths. Additionally, the levels appear to be getting lower yearly. Anderson Pond, being a eutrophic waterway, has high levels of nutrients, excessive algae growth, low light penetration, and is an environment, especially at depth, dominated by respiration, an O2 consuming process. Without the pump bringing deep water up to the surface for aeration, the pond would quickly become anoxic through most of the water column.
The most consistent O2 levels top to bottom are seen in winter. The more stormy, windy weather could have had the effect of better aerating the pond and churning O2 rich water to the bottom Additionally, respiration reactions are temperature dependent and are limited by colder water.