ABSTRACT
ABSTRACT: The faecal bacteria concentration distribution in bottom sediment affect its concentration in over-lying water greatly. The partition coefficients and porosity affect the concentration distribution of free-floating and adsorbed bacteria in bottom sediment, so they should have a great impact on faecal bacteria movement in surface waters. Both theoretical analysis and numerical computation are employed in this research. The bottom sediment partition coefficients and porosity impacts on faecal bacteria concentration in water column was studied by a simplified case. The results indicated that the concentration in over-lying water decreased with partition coefficients and porosity decreasing, but the concentration decreased caused by partition coefficients was much larger than that of porosity. The freefloating faecal bacteria concentration decreased and the adsorbed one increased with partition coefficients increasing, so the weakened direct resuspension decreased concentration in water column and the enhanced resuspension with sediment raised that concentration. Both free-floating and adsorbed bacteria concentration decreased with porosity increasing, therefore, the weakened direct resuspension and resuspension with sediment decreased the concentration in water column, but the decrease caused by resuspension with sediment was much larger than that caused by direct resuspension.
