Characteristics of phosphorus sorption at the sediment–water interface in Dongting Lake, a Yangtze-connected lake

Abstract

Phosphorus in sediments plays an important role in lake eutrophication. This study investigated the phosphorus sorption characteristics of sediments in a river-connected lake and identified the phosphorus source or sink areas in the lake. Sediment samples with different physicochemical characteristics were collected in 2011 and 2013 from Dongting Lake, which is connected to the world's third longest river, the Yangtze. Batch incubation experiments were conducted to determine the phosphorus sorption characteristics of the sediment samples. The sediment sample from Luzui (D3) exhibited the highest sorption capacity in 2013 (0.75 mg g−1) because of its large proportion of fine particles ( 0.91). The calculated results (equilibrium phosphorus concentration, 0.025–0.032 mg L−1) indicated that the estuary from Dongting Lake to the Yangtze River (D1) served as a phosphorus sink because of the large proportion of fine particles and low total phosphorus content in the sediments. The east Dongting Lake (D2 and D3) with a high phosphorus concentration served as a phosphorus source. Yugong Miao (D4) and Nanzui (D5) had a low phosphorus concentration in water because of their location and flow field, respectively.

Keywords

• kinetics
• modified models
• phosphorus
• sediment
• sorption