土壤中溶解性有机质（FA和HA）影响着矿质元素的植物有效性，但目前其对锗（Ge）植物有效性的影响机制尚不清楚。本研究以云南临沧锗矿区大叶种茶园为研究对象，采用茶树盆栽试验，考察FA和HA对茶树不同组织中Ge含量的影响，查明FA和HA对Ge植物有效性的影响机制。采用水培试验，研究FA、HA和根细胞壁（CW）对Ge离子吸附的动力学和热力学，探讨“FA-CW-Ge”和“HA-CW-Ge”三元体系中三者之间的交互关系及FA和HA对茶树根系吸附、吸收Ge离子的影响，揭示其影响茶树根部吸附、吸收Ge进而向地上部组织转运的分子机理。将盆栽与水培试验相结合，运用TEM、SRXRF等手段，厘清FA和HA对茶树各组织细胞累积Ge的影响；采用XANES手段，揭示FA和HA对土壤及茶树各组织内Ge分子形态的影响；进而阐明FA和HA影响茶树Ge吸收与形态转化的分子机制。研究成果可为富锗土壤的深度开发提供理论支持。

Germanium (Ge) is a representative mineral resource and the large leaf tea is a special agricultural product in Yunnan province. In recent years, with the discovery of "potential biological activity" of organic Ge, the study on phytoavailability of Ge is attracting more and more attention. China is rich in Ge-rich soil resources, however, the phytoavailability of Ge is very poor, which seriously restricts the further exploitation and utilization of Ge-rich soil resources. Previous researches identified that soluble humus fractions, i.e. fulvic acid (FA) and humic acid (HA) in soils are closely relate to the phytoavailability of Ge; however, its influence mechanism on Ge phytoavailability for large leaf tea plants (Camellia sinensis var. assamica) is still unclear. Therefore, in this project, the large leaf tea plants at Lincang Ge mining area in Yunnan province is selected as research object and the influence mechanism of FA and HA on Ge phytoavailability is focused on.. Firstly, pot experiments will be adopted to investigate the influence of FA and HA (exogenous inputs) on microbial biomass in rhizosphere and non-rhizosphere soils, and the changes of Ge concentrations in various tissues of tea plants as well. The characteristics of speciation distribution changes of Ge in various tissues of tea plants and the influence mechanism of FA and HA on Ge phytoavailability will be clarified by using fourier transform infrared (FTIR) spectrometry and scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) techniques.. Secondly, hydroponic experiments will be carried out to investigate the adsorption kinetics and thermodynamics of FA, HA and root cell wall (CW) on Ge ions. FTIR will be employed to characterize the changes of characteristic functional groups of FA, HA and CW before and after the sorption of Ge ions. The interaction of Ge with FA, HA and CW in "FA-CW-Ge" and "HA-CW-Ge" ternary system, and its influence on the sorption and uptake of Ge ions in tea roots will be investigated respectively. Then the influence mechanisms of FA and HA on the Ge sorption and uptake in tea roots and further transportation to aerial part will be revealed.. Finally, the pot and hydroponic experiments will be combined to identify the effects of FA and HA on the accumulation of Ge in tea tissues and cells by means of differential centrifugation, ICP-MS, TEM and synchrotron radiation X-ray fluorescence (SRXRF). The effects of FA and HA on the Ge molecules speciation in soil and tea plant tissues will be revealed by means of X-ray absorption near-edge structure (XANES) spectra. The influence mechanism of FA and HA on the Ge phytoavailability of large leaf tea plant in Yunnan will be elucidated at the tissue, cell and molecular (atomic) scales. The findings will provide theoretical support for further exploitation and utilization of Ge-rich soil resources.