HR: 08:15h
AN: H41J-02    [Abstracts]
TI: Using Zn isotopes to investigate trace metal partitions between dissolved and suspended loads in the Seine River, France
AU: * Chen, J
EM: chen@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, 2 etage, T14-24, 4 Place Jussieu, Paris, 75005, France
AU: Gaillardet, J
EM: gaillardet@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, 2 etage, T14-24, 4 Place Jussieu, Paris, 75005, France
AU: Louvat, P
EM: louvat@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, 2 etage, T14-24, 4 Place Jussieu, Paris, 75005, France
AB: Recent improvements in MC-ICP-MS allow measuring isotope compositions of Zn, a particular interesting element due to its five isotopes, bio-vital nature, essential use and global presence, this makes Zn isotopes a potential device to investigate metal comportments in geochemical and biochemical system, but only few studies have focused on Zn isotopes in aqueous environment, leaving an important gap in research of Zn hydrological and geochemical cycle. Our research focusing on the Zn isotope geochemistry in the largely anthropized Seine River completes the gap of recent works on Zn isotopes, moreover it is the first in depth study using Zn isotopes to assess the metal partition between dissolved and particulate phases since it plays an important role in the transport and the fate of trace metals in water system.
We have developed a new protocol of two-column separation of Zn from dilute aqueous solution, the protocol is proven to be reproducible by tests on standard-doped distilled and column-purified Seine river waters, the mean δ⁶⁶Zn value is -0.006‰ for all purification tests with an average yield of about 100%, permitting accurate measurement of Zn isotopes ratios in samples of the Seine watershed. Repeated measurements of Zn AAS standard (Alfa Aesar) on MC-ICP-MS (Neptune) during two years led to a precision of 0.04‰ (2s). Preliminary results show a total variation of 0.65‰ for δ⁶⁶Zn in dissolved phases of the Seine basin, and a light isotope enrichment in anthropogenic sources compared to other water samples. The determined conservative behaviour of Zn in river water makes Zn isotopes an effective probe of anthropogenic contamination. Suspended particular matters (SPM) display different Zn isotope compositions compared to dissolved loads. Zn concentrations and its isotope compositions in SPM reveal inverse relationships as function of the distance from the headwater and the SPM content for geographical and temporal samples, respectively. Isotopic offsets between particulate and dissolved phases show variable relationships according to the major element ratio, the SPM content and other parameters, providing us more clues about mechanisms controlling trace metals partitions in river water system.
DE: 1041 Stable isotope geochemistry (0454, 4870)
DE: 1065 Major and trace element geochemistry
DE: 4870 Stable isotopes (0454, 1041)
SC: Hydrology [H]
MN: 2007 Fall Meeting