The Sr isotopic fractionation caused by poplar trees and the implications to the environments

  • 江 易璇

Student thesis: Master's Thesis


Triple Strontium (Sr) isotopes have been extensively applied as tracers for weathering processes in the terrestrial environments Plants located on the of rock-water-soil interface and have been known to accelerate the weathering rate when they mobilizes metals from soils Recent studies showed plants may play a non-negligible role in the biogeochemical cycle of strontium using the δ88/86Sr but the relationship between plants and the environments were still unclear Here we aim to use δ88/86Sr to demonstrate how plants affect the δ88/86Sr in soil even evaluate the plant influence to the chemical weathering process in forest systems The poplar trees that cultivated at the Swiss Federal Research Institute for four months were chosen for the experiments We used an empirical external normalization (EEN) combined with standard-sample bracketing (SSB) procedures to correct the potential mass drifting during Sr isotopes measurements on multiple-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) The results allow to identify a three-step Sr isotopic fractionation levels in poplar trees The first one takes place when Sr entering the root The second one takes place as Sr transported from root to stems followed during the Sr translocation from stem to leaves and δ88/86Sr decreased with height The average poplar δ88/86Sr value (-0 18?) showed enrichment of 86Sr compare to the soil solution (δ88/86Sr =0 02?) According to an estimation using Rayleigh fraction model poplar trees can produce significant δ88/86Sr fractionation in water which up to 2 99? if all the dissolved Sr was removed by the poplar trees This supported the vegetation is the lighter 86Sr reservoir and likely plays an important role in Sr cycling in terrestrial environments
Date of Award2015 Aug 17
Original languageEnglish
SupervisorChen-Feng You (Supervisor)

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