The formula for rate of change of nitrate within an agricultural soil is similar to the formula for rate of change of nitrate within the wetland. The difference between the two equations is that the water content is multiplied by the soil volume in order to find the volume of water within the wetland. Calculate the rate of change of nitrate concentration within the Lakeside wetland. The average or the initial volume could be used in the rate equation. Initial gives the reaction rate at the beginning of the time step, and average gives the average reaction rate over period of the time step.
Relevant information is tabulated below.
The second step is calculation of nitrate mass leaving the soil. Nitrate concentration in seepage or drainage from the soil is the same as nitrate concentration in soil-water. We reviewed the continuity quantity and rate equations for nitrogen concentration in soils and wetlands. If you understand these equations, then you understand the fundamental theory behind equations for all contaminant transport and degradation in the environment. The only difference between the continuity equation as applied in this lecture and other environmental contaminant transport equations is that 4 terms in the equation are defined differently.