Effect of Leptolyngbya sp. Biofilm and Vallisneria natans Growth on Nutrient Release from Sediment

Abstract

Nutrients supplied by sediment of lakes and light are likely important factors determining the growth balance between Leptolyngbya sp. biofilm and Vallisneria natans. Therefore, experiments with varying light are conducted to compare the effect of nutrient release from surface sediment on their growth. The results show that changes in pH, dissolved oxygen (DO) and redox potential (Eh) are significantly correlated with the changes in nitrogen(N) and phosphorus (P) concentrations in the water (p < 0.05). The optimum light intensity for the growth of Leptolyngbya sp. and V. natans is different. The biomass of Leptolyngbya sp. biofilm is higher at 2–27 µmol m−2·s−1, but the biomass of V. natans is positively correlated with light intensity (2–54 µmol m−2·s−1) (p < 0.05). The Leptolyngbya sp. biofilm and V. natans can retain P from sediment and significantly remove N in the overlying water. The total P amounts retained by V. natans are significantly higher than that of Leptolyngbya sp. biofilm in all treatments, and the potential for P retention of V. natans increases with the increase of light intensity. The retention of P amounts in the Leptolyngbya sp. biofilm mainly formed 47.8% Fe‐bound P, but 57% NH4CI‐bound P in the V. natans.