80 sediment compartments are useful in the present analysis (the transfer rates are shown in Figure I-4), i.e.: ??? = ?? ? ?? ?(?? ?? ? ???) + ? ? ? ??(?? ?? ? ???) + ??? ? ?? ?(?? ?? ? ???) + ?????(???) ?(?? ?? ? ???) (I-5) ??? = ? ???[?? ???(???)] + ??? ? ? ???(???) + ?????(???) ??[?? ???(???)] (I-6) ??? = ? ? ? ???[?? ???(???)] + ?? ? ?? ??[?? ???(???)] (I-7) ??? = ? ? ? ?????[?? ???(???)] (I-8) ??? = ?? ? ?? ???[?? ???(???)] (I-9) FIG. I-4. Generic vertical structure of the water–sediment compartments. Here kSW is composed of expressions describing the transfer of activity by sedimentation, molecular di?usion, pore water mixing and particle mixing, respectively. Similarly, kSW is composed of expressions describing the transfer of radioactivity by molecular diffusion, pore water mixing and particle mixing. kSM is composed of expressions describing the transfer of radioactivity by sedimentation and molecular di?usion. kMS corresponds to the transfer by molecular di?usion. Finally, kMD corresponds to the transfer of radioactivity by sedimentation. Rw (m/y) is the sediment reworking rate; RT (y?1) is the porewater turnover rate; kd (m3/t) is the sediment distribution coe?cient; SSL (t/m3) is the suspended sediment load in the water