Mapping Phosphorus Availability in Soil at a Large Scale and High Resolution Using Novel Diffusive Gradients in Thin Films Designed for X-ray Fluorescence Microscopy

Abstract

A novel binding layer (BL) as part of the diffusive gradients in thin films (DGT) technique was developed for the two-dimensional visualization and quantification of labile phosphorus (P) in soils. This BL was designed for P detection by synchrotron-based X-ray fluorescence microscopy (XFM). It differs from the conventional DGT BL as the hydrogel is eliminated to overcome the issue that the fluorescent X-rays of P are detected mainly from shallow sample depths. Instead, the novel design is based on a polyimide film (Kapton) onto which finely powdered titanium dioxide-based P binding agent (Metsorb) was applied, resulting in superficial P binding only. The BL was successfully used for quantitative visualization of P diffusion from three conventional P fertilizers applied to two soils. On a selection of samples, XFM analysis was confirmed by quantitative laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The XFM method detected significant differences in labile P concentrations and P diffusion zone radii with the P fertilizer incubation, which were explained by soil and fertilizer properties. This development paves the way for fast XFM analysis of P on large DGT BLs to investigate in situ diffusion of labile P from fertilizers and to visualize large-scale P cycling processes at high spatial resolution.

Dose-Dependent Effect on Plant Growth of Exposure to Metal–Organic Framework MIL-101(Cr)

“…LA-ICP-MS is a powerful analytical tool that has the advantages of low detection limits, high throughput, high sensitivity, and low sample consumption. Importantly, it is capable of in situ analysis of multiple elements in solid samples, including the distribution and transport of metal nanoparticles in plants. − Therefore, we imaged the plants exposed to 100 mg/L MIL-101­(Cr) for 7 days using LA-ICP-MS.…”