A system of two or more connected reservoirs in which material or energy is

# A system of two or more connected reservoirs in which

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A system of two or more connected reservoirs in which material (or energy) is transferred in cyclical fashion A way of understanding and modeling where substances come from, where they go, ǁheƌe theǇ ͚ƌeside͛ iŶ the Eaƌth sǇsteŵ, aŶd hoǁ theǇ aƌe tƌaŶsfoƌŵed aŶd tƌaŶsfeƌƌed Many but not all natural processes are best described as cycles Matter and energy in systems and cycles obey the rules of thermodynamics but they behave somewhat differently: o Matter is recycled through environmental systems, changing form as it goes o Energy comes into the earth system, flows through, is used and degraded and then exits the system o Energy cannot be crated or destroyed but it can be degraded and transformed Matter and energy are essentially equivalent; Conservation of mass = conservation of total energy o ‘eseƌǀoiƌs ;oƌ ͚pools͛Ϳ ĐaŶ ďe defiŶed ďǇ: PhǇsiĐal ďouŶdaƌies ; like a ͚holdiŶg taŶk͛Ϳ The ocean An organism A magma chamber under a volcano *Question: Can a reservoir also be a system?* CoŶteŶts ;a ͚ŵass͛ of ŵateƌialͿ Ozone in the stratosphere Fish in the ocean Mercury in ocean fish *Question: Do all parts of the content of a reservoir have to be contiguous?* Cycles can be portrayed visually, graphically, or mathematically o When we construct a portrayal of the characteristics and functioning of a cycle oƌ aŶǇ otheƌ eŶǀiƌoŶŵeŶtal pƌoĐess, it͛s Đalled a ŵodel o Models of natural cycles and other processes can be Physical models Landscape drawings Box models find more resources at oneclass.com find more resources at oneclass.com
Hadia Saeed Mathematical models o Simple landscape drawing of hydrological cycle o Simple box model of hydrological cycle Cycles can be portrayed quantitatively using models o Boǆ ŵodels tǇpiĐallǇ giǀe ƋuaŶtitatiǀe iŶfoƌŵatioŶ aďout… Reservoirs (=boxes) Content (= numbers in the boxes) Transfer processes (= arrows) Fluxes (= numbers on the arrows) o Box models are the first step in developing mathematical and computer models Each process, flux, etc. is described by a mathematical equation o Models of environmental systems can be very complicated find more resources at oneclass.com find more resources at oneclass.com
Hadia Saeed o Simple 2-reservoir example : The sodium cycle The content of a reservoir is a function of both concentration and overall size o Content (or burden) or a reservoir =total mass of a substance in the reservoir =concentration x mass of a physical unit Example: content of sodium (Na) in seawater =10.78 g/kg (salinity of seawater) x 1.4 x 10 21 kg (total mass of the ocean) =15.1 x 10 21 g = burden of Na (as NaCl) in seawater o Compare: small, high-concentration reservoir vs. large, low-concentration reservoir o The Sodium Cycle Some Questions to think about: Hoǁ ǁould Ǉou ĐalĐulate the ĐoŶteŶt of Na iŶ the ďoǆ laďelled ͚ƌoĐks͛ oŶ the sodiuŵ cycle box model?

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