Improvement of water quality by sediment capping and re-vegetation with Vallisneria natans L.: A short-term investigation using an in situ enclosure experiment in Lake Erhai, China

This study evaluated the effects of sediment capping with local unpolluted soil and re-vegetation with Vallisneria natans on the water quality in a two-month in situ experiment in a mesotrophic lake. Water quality was improved substantially by sediment capping whether alone or along with re-vegetating using V. natans, although varied greatly with time. Sediment capping was an effective technique to reduce nitrogen (N) and phosphorus (P) release from fertile sediment, which thus inhibited phytoplankton growth in the water column. Re-vegetation using V. natans helped to improve water quality slightly more. Sediment capping alone or along with re-vegetating also changed interactions of the water quality parameters substantially. Compared to the control, sediment capping alone enforced the relationships between Chl-a and both SD and K, but along with re-vegetation weakened the relationships. In addition, sediment capping alone enforced the relationship between Chl-a and N-NH4, but with or without along with the re-vegetation the relationships between Chl-a and both TN and N-NO3 decreased.