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Lake stratification is the tendency of lakes to form separate and distinct thermal layers during warm weather. Typically stratified lakes show three distinct layers: the epilimnion, comprising the top warm layer; the thermocline (or metalimnion), the middle layer, whose depth may change throughout the day; and the colder hypolimnion, extending to the floor of the lake.
Abiotic changes in dissolved gases include exchanges of dissolved gases between the atmosphere and lake surface, vertical or horizontal entrainment of water with differing concentrations (e.g. low-oxygen water below a lake's thermocline), or import and export of dissolved gases from inflowing streams or a lake outlet.
While oxygen can typically exchange between surface waters and the atmosphere (i.e., in the absence of ice cover), bottom waters are comparatively isolated from atmospheric replenishment of oxygen. In particular, during periods of thermal stratification , gas exchange between the epilimnion and hypolimnion is limited by the density difference ...
A deep-water oxygenation system could be in the cards for Lake Hopatcong, New Jersey's largest lake, as stakeholders seek to stifle the kind of harmful algal blooms that effectively closed it in 2019.
Due to the stable density gradient, mixing is inhibited within the thermocline, [8] which reduces the vertical transport of dissolved oxygen. If a lake is eutrophic and has a high sediment oxygen demand, the hypolimnion in dimictic lakes can become hypoxic during summer stratification, as often seen in Lake Erie.
During periods of thermal stratification, water density gradients prevent oxygen-rich surface waters from mixing with deeper waters. Prolonged periods of stratification can result in the depletion of bottom-water dissolved oxygen; when dissolved oxygen concentrations are below 2 milligrams per liter, waters are considered hypoxic. [22]
Lake stratification ... Additionally, the epilimnion is typically has a higher pH and higher dissolved oxygen concentration than the hypolimnion. Physical Structure
In warm monomictic lakes, thermal stratification lends to oxygen depletion in the hypolimnion; a lack of mixing prevents the introduction of oxygen from the atmosphere into the water. This measure is known as dissolved oxygen (DO). When DO is lowered in the hypolimnion, nutrients like ammonium, nitrate, and phosphates tend to dominate.