Fig. 3. (a) Parameter-specific P assimilative capacity calculated as the amount of P absorbed by an area of marsh over the time period before significant change in that parameter. (b) Dose-dependent downstream travel rates of significant alterations in measured parameters. The rates are applicable to marsh receiving P input from a control structure with a water depth of 0.5 to 1 m and input velocity of 2 to 15 mm s^–1.