High-resolution imaging of labile phosphorus and its relationship with iron redox state in lake sediments

• Published in: Environmental pollution (1987) 2016-12, Vol.219, p.466-474
• Main Authors: Gao, Yulu, Liang, Tao, Tian, Shuhan, Wang, Lingqing, Holm, Peter E., Bruun Hansen, Hans Christian
• Format: Article
• Language: English
• Subjects: China; DGT; Diffusion; Environmental Monitoring - methods; Eutrophication; Geologic Sediments - chemistry; High resolution; Iron; Iron - analysis; Iron - chemistry; Lakes - chemistry; Oxidation-Reduction; Phosphorus; Phosphorus - analysis; Sediment-water interface; Water Pollutants, Chemical - analysis
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2016.05.053

A thorough understanding of the labile status and dynamics of phosphorus (P) and iron (Fe) across the sediment-water interface (SWI) is essential for managing internal P release in eutrophic lakes. Fe-coupled inactivation of P in sediments is an important factor which affects internal P release in freshwater lakes. In this study, two in-situ high-resolution diffusive gradients in thin films (DGT) techniques, Zr-Oxide DGT and ZrO-Chelex DGT, were used to investigate the release characteristics of P from sediments in a large freshwater lake (Dongting Lake, China; area of 2691 km2) experiencing a regional summer algal bloom. Two-dimensional distributions of labile P in sediments were imaged with the Zr-Oxide DGT without destruction of the original structure of the sediment layer at four sites of the lake. The concentration of DGT-labile P in the sediments, ranging from 0.007 to 0.206 mg L−1, was highly heterogeneous across the profiles. The values of apparent diffusion flux (Fd) and release flux (Fr) of P varied between −0.027–0.197 mg m−2 d−1 and 0.037–0.332 mg m−2 d−1, respectively. Labile P showed a high and positive correlation (p