title: An investigation of the effects of elevated phosphorus in water on the release of heavy metals in sediments at a high resolution.
abstract: Excessive phosphorus (P) input plays an important role on the release of heavy metals in sediments under the eutrophic environment. In this study, a microcosm experiment with 40-day incubation using homogenized sediments was performed to investigate this aspect at a millimeter resolution. Diffusive gradient in thin films (DGT) and dialysis (Peeper) techniques were employed to simultaneously measure labile and dissolved P, Pb, Cd, Zn, Co and Ni in sediments at a millimeter scale, respectively. The results showed that an increase of water P from 0.02mgL-1to 0.20 and 2.4mgL-1generally led to intensified decrease of DGT-labile metals from the 10th to 20th days after the onset of incubation. The decrease in dissolved metals in pore water also appeared on the 20th day. The degree of decrease in the five metals was in the order of Pb>Cd>Zn>Co>Ni, which has a negative correlation with the solubility constants (Ksp) of each metal-P precipitate. This indicated that the negative effect was caused by the precipitation of metal P. On the 40th day during incubation, the concentrations of DGT-labile metals had different increasing pattern compared to those on the 20th day. The extent of metal recovery was positively correlated with the change of desorption rate constant (k-1) and negatively correlated with the change in the characteristic time (Tc) to reach equilibrium from DGT perturbation derived from DGT-induced fluxes in sediments (DIFS) modeling. This suggested that the recovery of metal lability from elevated water P was a result of the increased releases of metals from sediment solids.
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: Musong
authors.initials: M
authors.lastname: Chen
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: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China.
authors.forename: Liping
authors.initials: L
authors.lastname: Zhang
authors.affiliation: School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
authors.forename: Yangyang
authors.initials: Y
authors.lastname: Li
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: International Network for Environment and Health, School of Geography and Archaeology, National University of Ireland, Galway, Ireland.
authors.forename: Chaosheng
authors.initials: C
authors.lastname: Zhang
keywords: DGT-induced fluxes in sediments; Diffusive gradients in thin films; Heavy metals; Phosphorus; Precipitation