[Study on phosphorus adsorption characteristic of sediments in an ecological ditch]

Sediments properties and phosphorus (P) adsorption capacities were compared among the samples of 0-5 cm and 5-15 cm layers from the ecological ditch vegetated with Cenetlla asiatica, Sparganium stoloniferum and a natural agricultural ditch with weeds. The results showed the 0-5 cm sediment vegetated with Cenetlla asiatica had higher concentrations of oxalate extracted Fe, Al and P than those vegetated with Sparganium stoloniferum or weeds. The parameters calculated from the Freudlich and Langmiur isotherms showed the equilibrium phosphate concentration (EPC0) ranged from 0.009 to 0.031 mg x L(-1). Cenetlla asiatica in the 0-5 cm layer had the maximum values of 352.2 L x kg(-1) and 562.7 mg x kg(-1) for Freundlich adsorption constant (K(f)) and Langmuir sorption maximum (S(max)), respectively, which proved it had the highest P adsorption capacity. The regression analysis showed P sorption parameters had significant relationship to oxalate-extracted Fe, clay content and DPS (P < 0.05). It was thus clear that aquatic plants influenced sediment properties and P adsorption capacity, and the practice of growing proper plants in ecological ditch could reduce the risk of P loss in non-point source pollution.