Technical note: On additivity of coagulation kernels

Two solutions of the aerosol dynamics equation are obtained using the method of sectional representation, The first one is for the case when the coagulation kernel is the sum of the individual kernels, The second one, used as the reference solution, is based on the unified theory of coagulation developed by Williams. The gravitational settling is taken as the removal mechanism. The parameters of the obtained approximate solutions are compared with each other and some conclusions are drawn.