title: In situ, high-resolution imaging of labile phosphorus in sediments of a large eutrophic lake.
abstract: 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.
authors.affiliation: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China. Electronic address: smding@niglas.ac.cn.
authors.forename: Shiming
authors.initials: S
authors.lastname: Ding
authors.affiliation: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Han
authors.affiliation: College of Forest Resources and Environment, Nanjing Forestry University, Nanjing 210037, China.
authors.forename: Yanping
authors.initials: Y
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Yao
authors.affiliation: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
authors.forename: Di
authors.initials: D
authors.lastname: Xu
authors.affiliation: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China.
authors.forename: Qin
authors.initials: Q
authors.lastname: Sun
authors.affiliation: Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, Belfast BT9 7BL, United Kingdom.
authors.forename: Paul N
authors.initials: PN
authors.lastname: Williams
authors.affiliation: GIS Centre, Ryan Institute and School of Geography and Archaeology, National University of Ireland, Galway, Ireland.
authors.forename: Chaosheng
authors.initials: C
authors.lastname: Zhang
mesh_terms: D002681:China; D004058:Diffusion; D004784:Environmental Monitoring / Q000379:methods; D019015:Geologic Sediments / Q000737:chemistry*; D060106:Lakes / Q000737:chemistry*; D010758:Phosphorus / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D014874:Water Pollutants, Chemical; D010758:Phosphorus
keywords: Eutrophication; High resolution; Phosphorus; Sediment-water interface; Zr-oxide DGT