rectilinear and curvilinear kernels (Figure 13.4). These calculations use a sectional approximation for the integral forms of the coagulation equations.41 The results show significant differences in steady-state particle concentrations (Figure 13.4a), timing and magnitude of particle flux (Figure 13.4b), and average particle settling velocity (Figure 13.4c).

The maximum particle concentration is higher for the curvilinear kernels than for rectilinear, as should be expected from the more rapid rates of coagulation (Figure 13.4). The steady-state concentrations of single algae for the rectilinear and curvilinear kernels are 0.17 and 2.0 times the critical concentration calculated using Equation (13.3) This higher value for the curvilinear kernel reflects the slower rates of collision when using it.

Another difference is in the maximum total particle volumetric flux rate out of the surface mixed layer, 49 and 488 cm3 m-2 per day for the rectilinear and curvilinear kernels, respectively. This dramatic increase for the curvilinear calculation is a result of the larger particle concentrations available for removal when the coagulation begins to dominate the growth. The peak average settling velocity is larger for the rectilinear kernel, 20 vs 12 m per day. The lower average settling velocity is a reflection of the smaller average particle size in the curvilinear case.

The implication of this comparison is that the form of the coagulation kernel can have a profound effect on properties that are ecologically significant, including particle concentration and, even more dramatically, particle flux. Developers of models need

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