![]() ![]() This is a dramatic event for the lake as well as the fish that live in the lake. The smell comes from hydrogen sulfide gases that were trapped at the bottom of the lake as aquatic plants and materials break down and collect on the lake’s bottom, then released throughout the water column by the turnover. If you are on this body of water during the year, you will notice an obvious smell, and decomposed material that was on the bottom of the lake is now on top. After a few days or weeks, the lake settles down into Winter Stratification. This effect will end result will make the lake’s water entirely uniform in temperature and oxygen. Water at lower temperatures and denser can mix much easier. This will cause the cause of Turnover and makes the whole lake mix with the water column of the entire lake, called the Fall Turnover. When the Fall Turnover happens, prevailing winds over the surface start to get colder and slowly cool down the top layer, which makes the surface water, with the help of these cold winds, heavier and causes them to sink. Once thermal stratification sets up, the deeper Hypolimnion level does not get mixed to the surface, and whatever dissolved oxygen exists in the Epilimnion level of the lake is all that is available until lake turnover in the fall. Spring turnover in a body of water is important for the same reason as Fall Turnover. Water is exposed to oxygen producers like plants, algae, and other microorganisms using Photosynthesisers exchanging carbon dioxide and expelling Oxygen.Water is closer & opened up to the atmosphere.That cooled level of water is the Thermocline level of the lake. The water drops right down to cool, not far down off the surface of the lake. In fact, the top few feet depending on how deep the lake is can be quite warm, almost the same temperature as the air on top of the boat. There is a huge difference in temperature. If you have ever been out on a boat in a deep lake and decided to jump out and go for a swim, you can really feel the difference in the layers from the top warm water level to the Thermocline level if you dive deep enough and hit the top of it. The deeper the lake, the larger the gradients become in the Thermal Stratification. The coolest water at this level is the densest and weighs the most, while the warmer water in the Epilimnion is less dense. The decomposing organic matter at the lake bottom contributes to the low dissolved oxygen content. Below that line, the Hypolimnion, which is a level with the lowest oxygen levels, discourages fish from living there. Above the thermocline, fish survive comfortably in the oxygen-rich water. Oxygen levels will also decrease beneath this line. It also contains water with a maximum density and temperatures of 4☌ or 39.2° Hypolimnion level is the deepest and coldest of water levels and does not mix with the other layers, and it has low circulation.This layer is also called the Thermocline because of its rapid decrease in temperature and O2 concentration levels. Metalimnion level– is the middle level that is characterized by a steep gradient in temperature and is the barrier that prevents mixture and the heat exchange between the Epilimnion level and the Hypolimnion levels in the lake.Epilimnion level is the top level that is constantly mixed by wind and waves and is warmed by the sun from the late spring to late Fall.For most of the year, there are layers separated by temperatures and density differences. In Winter, there is no Stratification as the whole lake cools and the overall temperature of the water becomes uniform. The sun warms the uppermost layer, and cooler water separates into 2 more layers. The lake will have 3 different layers of temperature. Algae Oxygen in Lake Turnover When Does Lake Turnover Occurīecause of the wide range of temperatures in lake water, Thermal Stratification is a typical natural occurrence.If not for this unique property of water, lakes would freeze solid from the bottom up, and there would be little, if any, chance for living things to exist in them. Water molecules become less dense and spread further apart as water freezes. When most compounds change from liquid to solid, they become heavier. Water is a wonderous element here on Earth when water freezes to ice, it floats. Wind & Sun heat & Mix surface to about 50☏.Nature constantly keeps changing, making itself better and repairing itself in a finely balanced way that just is amazing and the more time you spend outdoors the more you understand how complicated and fragile it is, like how a few degrees in temperature can move huge amounts of water in the deepest lake not only once but twice a year every Spring and Fall.
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