共存阳离子作为土壤溶液的重要组成部分，显著影响重金属离子的根系界面迁移过程。传统方法由于对样品的破坏性常造成测试结果无法合理解释甚至导致研究假象，而非损伤微测则能真实客观反映实际生理状态下共存阳离子对重金属离子的影响规律。本项目针对农田土壤Cd污染现状，以主要粮食作物小麦为研究对象，运用非损伤微测技术，探讨共存阳离子（Ca2+、Mg2+、Na+、K+、H+）影响活体小麦动态吸收转运Cd2+的过程及机制。通过单因子控制的方法，考察活体条件下不同阳离子对小麦根表动态吸收Cd2+的影响；基于生物配体模型的理论框架，定量评估共存阳离子的影响程度；监测代谢抑制剂和离子通道抑制剂作用下小麦根表Cd2+离子流变化，着重从离子传输的动态变化角度揭示共存阳离子影响小麦吸收转运Cd2+的主要途径和机制。通过本研究将有助于认识小麦吸收Cd2+的动力学过程机制，为农田土壤Cd污染风险评估提供科学理论依据。

As important constituents of soil solution, co-existing cations can substantially affect the transport of heavy metals on root surface. Traditional destructive technologies have limited capabilities in analyzing root samples and sometimes may result in false conclusion. The Non-invasive Micro-test Technology (NMT) enable us to study the impact of co-existing cations on heavy metals under the real physiological condition.This project is designed to investigate the kinetic transport of cadmium ion (Cd2+) at root surface of wheat as affected by co-existing cations (Ca2+, Mg2+, Na+, K+ and H+). Laboratory experiments using non-invasive microtest technology will be carried to characterize Cd2+ uptake kinetics with the existence of individual cations at different concentrations. The Biotic Ligand Model (BLM) will be employed to quantify the conditional binding constants (Log KMBL) between different cations and biotic uptake sites (Biotic Ligand) on root surface of wheat. Furthermore, the physiological mechanism of Cd2+ transport will be examined using metabolic inhibitors and ion channel blockers. The objectives of this study are: 1) to determine the effect of co-existing cations on Cd2+ uptake kinetics at the root surface of wheat; 2) to evaluate the applicability of the BLM model for quantification of co-ion effect on kinetic transport of Cd2+; and 3) to elucidate the physiological mechanism of Cd uptake and transport by wheat. The results from this project will improve our understanding of the mechanism and kinetics of Cd uptake processes and develop new tools for the environmental risk assessment of cropland soil cadmium contamination.