Sediment pollution and nitrogen release at the sediment‐water interface in Changjiang River and its tributary, the lower Han River Basin

Abstract

Surface and core sediments were investigated in the lower Han River Basin, a tributary of Changjiang River in China to evaluate the nitrogen (N) pollution of sediments and N fluxes as well as their influencing factors at the sediment-water interface. Two methods of sediment pollution assessment were applied and the results showed that the sediment at site H9 was the most contaminated and that at site H4 and H7 was almost unpolluted. pH was significantly and positively correlated with total nitrogen (TN) content and NH + 4 flux (P < 0.05), indicating that N fluxes could be related to environmental factors. NO − 3 was generally from out of the sediment and into water, while NH + 4 diffused into sediment from water at some sites. Overall, the N fluxes were extremely high, revealing the considerable risk in internal N release. It is of great importance to strengthen the ecological restoration and control the internal N release.

Characteristics of nutrients accumulation in the bottom sediment of the surface-flow constructed wetlands of Mata lake during its operational maturity，China

“…6). The increasing trend of TN content in the water column with time indicates that the bottom sediment acts as the water column pollution "source", which can release N to the overlying water bodies (Yuan et al, 2020).…”