作业帮氧垂曲线的特点和适用范围
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氧垂曲线的特点和适用范围
氧垂曲线的特点和适用范围
氧垂曲线的特点和适用范围
溶氧下垂曲线：
表示水中溶解氧含量沿河道的分布呈下垂状曲线.在排污口下游河水中,溶解氧含量因有机物生物氧化的脱氧作用而显著下降,又由于下游大气复氧和生物光合作用等而使溶解氧含量增加.下垂曲线的临界点(氧垂点),其溶解氧含量最小.
Oxygen Sag Curve
The discharge of wastes into a body of water results in the depletion of dissolved oxygen level as the wastes are oxidized by the bacteria.Opposing this drop in dissolved oxygen is reaeration which replaces oxygen through the surface,at a rate which is proportional to the depletion of oxygen below the saturation value.The simultaneous action of deoxygenation and reaeration produces a typical pattern in the dissolved oxygen concentration of the aquatic system.This pattern is known as the dissolved oxygen curve.
排入河体的废物经细菌的氧化后使水体的溶解氧迅速消耗,与这种下降作用趋势相反的是,氧气在水面得重新溶解,其溶解速率正比于细菌消
耗氧气速率,但小于饱和值.这种同时发生的耗氧与复氧作用可以产生一个典型的水体溶氧密度模型.这种模型就是所说的溶氧曲线.
The following applet plots the DO curve using the point source plug flow model.In this model it is assumed that there is a continuous discharge of waste at a given location on the river.As the water and the wastes flow downriver,it is assumed that there is no dispersion of wastes in the direction of flow.This model results in the classic Streeter-Phelps oxygen sag equation which is used in this applet.
下面的程序applet使用赛流模型点源绘出溶氧曲线.在这个模型是假定废物连续排放在河上在某个给定位置.当废物顺流而下时,废物不在河
水流向上发生扩散.使用该程序applet可以产生基于给定模型的经典菲尔普斯氧垂公式.
在河下游任意点处关于DO 的方程,由下给出
DO = DOs - [ kdLo(e-kdt - e-krt) / (kr - kd) + D0e-kdt]
DO = t 时间后的河水溶解氧,mg/l
DOs = 河水中溶解氧的饱和值,mg/l
D0 = (DOs - DOo) = 含有废物的河水中初始氧含量差,mg/l
kd = 脱氧速率常数,d-1
kr = 复氧速率常数,d-1
t = x/u = 废物随水流动时间,s
u =水流速,m/s 且 x = 下游与废物排放点的距离,m
Lo = 废物投入河水后的初始生物耗氧量.
程序网址如下