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Ding, SM,Han, C,Wang, YP,Yao, L,Wang, Y,Xu, D,Sun, Q,Williams, PN,Zhang, CS
2015
May
Water Research
In situ, high-resolution imaging of labile phosphorus in sediments of a large eutrophic lake
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Eutrophication High resolution Phosphorus Sediment-water interface Zr-oxide DGT DISSOLVED REACTIVE PHOSPHORUS THIN-FILMS TECHNIQUE FRESH-WATER LAKE DIFFUSIVE GRADIENTS METAL BIOAVAILABILITY MOBILE PHOSPHORUS SHALLOW LAKES PORE-WATER TAIHU LAKE CHINA
74
100
109
Understanding the labile status of phosphorus (P) in sediments is crucial for managing a eutrophic lake, but it is hindered by lacking in situ data particularly on a catchment scale. In this study, we for the first time characterized in situ labile P in sediments with the Zr-oxide diffusive gradients in thin films (Zr-oxide DGT) technique at a two-dimensional (2D), submillimeter resolution in a large eutrophic lake (Lake Taihu, China, with an area of 2338 km(2)). The concentration of DGT-labile P in the sediment profiles showed strong variation mostly ranging from 0.01 to 0.35 mg L-1 with a considerable number of hotspots. The horizontal heterogeneity index of labile P varied from 0.04 to 4.5. High values appeared at the depths of 0-30 mm, likely reflecting an active layer of labile P under the sediment -water interface (SWI). Concentration gradients of labile P were observed from the high-resolution 1D DGT profiles in both the sediment and overlying water layers close to the SWI. The apparent diffusion flux of P across the SWI was calculated between -21 and 65 ng cm(-2) d(-1), which showed that the sediments tended to be a source and sink of overlying water P in the algal- and macrophyte-dominated regions, respectively. The DGT-labile P in the 0-30 mm active layer showed a better correlation with overlying water P than the labile P measured by ex situ chemical extraction methods. It implies that in situ, high-resolution profiling of labile P with DGT is a more reliable approach and will significantly extend our ability in in situ monitoring of the labile status of P in sediments in the field. (C) 2015 Elsevier Ltd. All rights reserved.
10.1016/j.watres.2015.02.008
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