Contrasting exchanges of nitrogen and phosphorus across the sediment–water interface during the drying and re-inundation of littoral eutrophic sediment. (December 2019)

• Record Type: Journal Article
• Authors: Liu, Cheng; Du, Yiheng; Chen, Kaining; Ma, Shuzhan; Chen, Bingfa; Lan, Yuanming
• Is Part Of: Environmental pollution. Volume 255(2019)Part 3
• Publication Date: 2019-12
• Subjects: Sediment–water interface -- Diffusive flux -- Water level fluctuation -- Internal loading -- Lake Chaohu; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2019.113356
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: High water level fluctuations (WLFs) lead to periodic drying and re-inundation of sediments in the littoral area of eutrophic lakes. In this study, a series of littoral sediment cores were dried for different periods (5–30 d) and rewetted for 48 h. The sediment cores that dried for 30 d were then re-inundated for 90 d. The exchanges of nitrogen (N) and phosphorus (P) across the sediment–water interface (SWI) and the mechanisms were studied. The results showed that ammonium nitrogen (NH4 + –N) fluxes increased after 5–25 d of drying, which was followed by an obvious decrease after 30 d of drying. The decreased NH4 + –N fluxes remained at low levels during the 90 d re-inundation period. The soluble reactive P (SRP) fluxes decreased significantly after 15 d of drying. However, further re-inundation increased the SRP fluxes to their initial levels. The decreased water content and porosity, the oxidation of the sediment during drying, and the associated transformations of the N and P fractions in the sediment from drying to re-inundation influenced the exchanges of NH4 + –N and SRP across the SWI. The decrease of labile NH4 + –N in the sediment during drying was non-reversible, while the transformations between redox sensitive P (Fe-P) and aluminum-bound P were more likely to be reversible from drying to re-inundation. The increase of Fe-P during drying and dissolution of Fe-P during the re-inundation were responsible for the development of SRP fluxes from drying to re-inundation. Therefore, the periodic drying and re-inundation of the littoral eutrophic sediments reduced the release of NH4 + –N but accelerated the release of SRP from the sediment. This should be given more consideration for the remediation and management of eutrophication in the lake and other similar lakes with high WLFs. Graphical abstract: Image 1 Highlights: NH4 + –N flux decreased after 30 d of drying and the re-inundation. Decrease of labile NH4 + –N in sediment reduced NH4 + –N flux. SRP flux decreased shortly after drying but increased during re-inundation. Fe–P controls the exchange of P across the SWI from drying to re-inundation. Transformation of Fe–P is reversible from drying to re-inundation. Abstract : Alternating periods of drying and re-inundation because of water level fluctuations decrease the fluxes of NH4 + –N but increase the fluxes of SRP from the littoral eutrophic sediment.