To decipher the complex reactions controlling the bioavailability of heavy metals in soils, one of the important tasks is the understanding of the key reactions and factors that determine the speciation and spatial distribution of heavy metals in soils and the acquisition and translocation of heavy metals in plants. Thus, this study aimed at developming LA-ICP-MS method in conjunction with X-ray absorption (XAS) method for determining the speciation and spatial distribution of heavy metals in soils and plants. This work evaluated the accuracy, precision, sensitivity and detection limit of the methods in determining the contents of As, Cd, Cr, Cu, Hg, Ni, Pb and Zn in soil and plant samples and certified materials, and the feasibility and analytical performace of XAS in determining the speciations of those heavy metals in soil and plant samples. The results obtained by LA-ICP-MS were comparable to the counterparts of solution ICP-MS analysis in terms of accuracy and precision. To further improve the performance of the method, different quantitation strategies were employed. The results revealed that the appropriate selection of internal standard can improve the analytical performance of the LA-ICP-MS method in the analysis of As, Cd, Cr, Cu, Hg, Ni, Pb and Zn in soil and plant samples. Meanwhile, the good reproducibity of the LA-ICP-MS method indicated the feasibility of applying the method in determining the spatial distribution of heavy metals in soil and plant samples. The synergetic application of the LA-ICP-MS and synchrotron-based XAS methods provides the possibility in observing the distribution and transformation of metals within a heterogeneous sample, such as soils and plants, and at soil-plant root interfaces. The information was applied to investigate the key processes that determine the bioavailability and toxicity of heavy metals in soils and their transformation within the plants.

Heavy metals, Laser ablation inductively coupled plasma mass spectrometry, Elemental mapping