Influence of rewetting process on distribution and release of phosphorus in sediments of East Lake Dongting

Fractions and release amount of phosphorus in sediment from East Lake Dongting were analyzed in the process of rewetting with low flow velocities, to provide evidence for phosphorus biogeochemical recycle, risk assessment of endogenous phosphorus release and eutrophication control scheme in seasonal lakes. In this paper, sediments collected in Eastern Dongting were air dried before rewetted. Phosphorus fractions in sediments and water were analyzed and indicated that phosphorus in sediments transported into water and air during rewetting process. Release amount of phosphorus in sediments increased and release rate decreased during the rewetting process. Significant positive correlation was observed between phosphorus release amount and water velocity. Dissolved organic phosphorus had relatively stronger absorption ability onto suspended particulate matter, thus they transformed into particle phosphorus more quickly than dissolved reactive phosphorus. Inorganic phosphorus in sediments transformed into organic phosphorus, and bioavailable phosphorus in sediments increased in the beginning of rewetting process. However, in the following stage of rewetting process, organic phosphorus in sediments transformed to inorganic phosphorus, and bioavailable phosphorus decreased. The dominate component of inorganic phosphorus in sediments transformed from aluminum-bound phosphate to iron-bound phosphorus. And the dominate component of organic phosphorus transformed from moderately labile organic phosphorus to labile organic phosphorus in rewetting process. © 2018 by Journal of Lake Sciences.