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Particulate phosphorus and sulfur species in soil leachates assessed with microfocused XRF and XANES

Knowledge of macronutrients in micro/nanoparticles mobilised from agricultural land is very limited. Synchrotron X-ray fluorescence microscopy and X-ray atomic absorption near-edge structure spectroscopy at the P and S K-edges were used to simultaneously reveal the speciation of P and S in leached micro/ nanoparticles from Swedish Agricultural land.

Eutrophication of natural waters by nitrogen, phosphorus (P), and sulfur (S) remains a major pollution issue, with increased rates predicted due to population growth and climate change [1]. Of all nutrients, the loss of P from

arable land is of particular environmental concern, especially for the Baltic Sea, one of the largest brackish water areas in the world [2]. Under high-intensity rainfall events, surface runoff is the main route of nutrient loss from many agricultural soils. However, transport of colloidal and nanosized particles by preferential flow in macropores can be predominant in flat areas and is considered as the main pathway in the fine-textured soils of central Sweden [3].

Although precise knowledge is critical to predict environmental risks and reduce nutrient losses from agricultural land, the nature of these particles has long been poorly understood due to analytical limitations. In traditional studies, leached P is divided into broad categories of particulate (> 0.45 µm) and soluble (< 0.45 µm) forms, with little attention to whether

Fig. 69: a) Microscale variation in the distribution of phosphorus species and (b) average phosphorus and sulfur speciation in microparticles (> 0.45 μm) leached from Krusenberg.