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Wu Z.,Chinese Research Academy of Environmental Sciences | Wang S.,Chinese Research Academy of Environmental Sciences | Jiao L.,Dongtinghu Lake Ecological Observation and Research Station DEORS
Journal of Geochemical Exploration | Year: 2015

Element profiles/images in sediment porewater at five sites of Dianchi Lake (China) were measured by AgI/Chelex-100, ferrihydrite and Chelex-100 DGT (Diffusive gradients in thin films) probes for labile sulfide, metals and P. Based on DGT profiles, remobilization character and geochemical behavior of multi-elements at fine scale were assessed. Fe remobilization characters at five sites indicated the distinct Fe-reduction process. The correspondence of Fe and Cu/Al/Zn, and good linear correlation in profiles verified the co-release of them by Fe-redox process in some sites. The reduction of Fe (III) hydroxyoxide caused P-release from Fe-bound P in anoxic sediment and "internal P loading" character, which has been verified by the linear correlation (R =0.77) in the whole DGT-profiles of Fe/P and the co-existence of Fe/P peaks at same depths. The peak flux (1.13×10-6-1.10×10-5 μgcm-2 s-1), niche area (3.6×10-5-6.0×10-2 cm2), circularity (0.204-1.0) and RJM (4.02-6.62%) derived by CID (computer image densitometry) have revealed the existence of sulfide microniche in sediments. © 2015 Elsevier B.V. Source


Wu Z.,Chinese Research Academy of Environmental Sciences | Wu Z.,Dongtinghu Lake Ecological Observation and Research Station DEORS | Wang S.,Chinese Research Academy of Environmental Sciences | Wang S.,Dongtinghu Lake Ecological Observation and Research Station DEORS | And 5 more authors.
Environmental Science and Pollution Research | Year: 2015

Labile P, Fe, and sulfide with the high spatial resolution in sediment porewater of five sites (A–E) of Dianchi Lake (China) were measured at same locations using AgI/Chelex-100, Chelex-100, and ferrihydrite DGT (diffusive gradients in thin films) probes. DGT derived P/Fe/S concentrations in sediment porewater on millimeter or sub-millimeter scale in order to reveal the element remobilization process and the mechanism of “internal P-loading” of sediments in Dianchi Lake. Decomposition of alga biomass in the uppermost sediment layer and the reductive dissolution of Fe-bound P in the anoxic sediment were the two main processes causing P release. A dynamic numerical model-DIFS (DGT-induced flux in sediments) was used to assess sediment-P reactivity (capacity of solid pool and rate of transfer) and P release risk by kinetic parameter—TC (1089∼20,450 s), distribution coefficient—Kd (167.09∼502.0 cm3 g−1), resupply parameter—R (from 0.242 to 0.518), and changes of dissolved/sorbed concentration, R and M at the microzone of DGT/porewater/sediment. © 2015 Springer-Verlag Berlin Heidelberg Source


Wu Z.,Chinese Research Academy of Environmental Sciences | Wu Z.,Dongtinghu Lake Ecological Observation and Research Station DEORS | Wu Z.,Beijing Normal University | He M.,Beijing Normal University | And 4 more authors.
Environmental Earth Sciences | Year: 2015

A passive sampling technique—diffusive gradients in thin films (DGT) was used to determine profiles of 14 metals on fine scale at SWI of two sites in Yingkou coast and to investigate biogeochemical process of Mn/Fe and other metals. Based on DGT concentration/flux and biogeochemical mechanism, remobilization character of metals in sediment profile was studied. Both profiles of two sites indicated sharp peaks of Fe and Mn at anoxic sediment, which verified redox process of Fe/Mn with large fluxes. Especially, very large peaks of Mn at −9.75 cm (7.239 × 10−4 µg cm−2 s−1) and Fe at −9.25 cm (1.420 × 10−3 µg cm−2 s−1) at site 2 corresponding with sulfide concentrations at same depths in profile were used for the calculation of saturation index to assess the solubility of metal sulfide. Other metals in certain segments of profiles at two sites indicated coupled geochemical process between them and Fe/Mn. DGT probe should be a reliable tool to measure multi-metals in sediment porewater and to assess geochemical process in coastal area. © 2014, Springer-Verlag Berlin Heidelberg. Source


Wu Z.,Chinese Research Academy of Environmental Sciences | Wu Z.,Dongtinghu Lake Ecological Observation and Research Station DEORS | Wu Z.,Beijing Normal University | Wang S.,Chinese Research Academy of Environmental Sciences | And 4 more authors.
Environmental Earth Sciences | Year: 2015

The fine-scale profile (concentration/flux) of 14 metals at sediment/water interface (SWI) of Yingkou bay was measured by passive sampler-DGT (diffusive gradients in thin films) probe and HR-ICP-MS instrument. Fe profile in sediment porewater indicated redox reactions, which was verified by peaks at −6.75, −7.75, −8.75 and −11.75 cm. Mn profile in sediment porewater indicated redox-sensitive character with the continuous increase in profile from −3.75 to −5.75 cm, and the subsequent peaks at −6.25, −8.25, −9.75 and −11.25 cm. Both Fe and Mn profiles indicated low values at −10.25 cm, which was due to the formation of pyrite and the adsorption of Mn on it. The co-occurrence of some peaks and broad feature near peaks of trace metals and Fe/Mn at same depths of profiles indicated coupled geochemical process and co-remobilization. The diffusive fluxes of metals across SWI were also calculated and investigated. © 2014, Springer-Verlag Berlin Heidelberg. Source


Wu Z.,Chinese Research Academy of Environmental Sciences | Wu Z.,Dongtinghu Lake Ecological Observation and Research Station DEORS | Wang S.,Chinese Research Academy of Environmental Sciences | Wang S.,Dongtinghu Lake Ecological Observation and Research Station DEORS | And 2 more authors.
Journal of Geochemical Exploration | Year: 2015

Element profiles/images in sediment porewater at five sites of Dianchi Lake (China) were measured by AgI/Chelex-100, ferrihydrite and Chelex-100 DGT (Diffusive gradients in thin films) probes for labile sulfide, metals and P. Based on DGT profiles, remobilization character and geochemical behavior of multi-elements at fine scale were assessed. Fe remobilization characters at five sites indicated the distinct Fe-reduction process. The correspondence of Fe and Cu/Al/Zn, and good linear correlation in profiles verified the co-release of them by Fe-redox process in some sites. The reduction of Fe (III) hydroxyoxide caused P-release from Fe-bound P in anoxic sediment and "internal P loading" character, which has been verified by the linear correlation (R=0.77) in the whole DGT-profiles of Fe/P and the co-existence of Fe/P peaks at same depths. The peak flux (1.13×10-6-1.10×10-5μgcm-2s-1), niche area (3.6×10-5-6.0×10-2cm2), circularity (0.204-1.0) and RJM (4.02-6.62%) derived by CID (computer image densitometry) have revealed the existence of sulfide microniche in sediments. © 2015 Elsevier B.V. Source

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