Application of diffusive gradient in thin films in the study of phosphorus mobility at sediment-water interface: A case study of the outlet of Nansi Lake

Abstract

The diffusive gradients in thin film (DGT) technology have made rapid development and become the most commonly used passive sampling technology in recent years. Compared with other traditional methods, DGT can better simulate the absorption process of nutrients by organisms and express bioavailability. The study takes the outlet of Nansi Lake during the nonflood discharge period as the research object. DGT technique was used to analyze the DGT-labile phosphorus (P) distribution characteristics and release risk at the sediment-water interface (SWI). The results showed that the DGT-labile P concentration in sediment interstitial water is higher than that in the overlying water. There was a significant correlation between labile P and labile Fe (r=0.534, P<0.01) and similar trends, indicating that the release of labile P is related to the reductive dissolution of Fe oxide. In addition, the net diffusive flux of P based on labile concentration was 17.6ng/cm2∙day. P may be released from sediment to overlying water. This study is expected to provide a reference for the analysis and control of P migration and release at the outlet of Nansi Lake by DGT technology.