Micro and nano sized particles in leachates from agricultural soils: Phosphorus and sulfur speciation by X-ray micro-spectroscopy

Colloids and nanoparticles leached from agricultural land are major carriers of potentially bioavailable nutrients with high mobility in the environment. Despite significant research efforts, accurate knowledge macronutrients colloids is limited. We used multi-elemental synchrotron X-ray fluorescence (XRF) microscopy multivariate spatial analysis atomic absorption near-edge structure (XANES) spectroscopy at P S K-edges, to study speciation two fractions particles, >0.45 <0.45 µm respectively, collected four tile-drained sites Sweden. K-edge XANES showed that organic P, followed by adsorbed surfaces aluminum-bearing particles were most common forms P. Iron-bound (Fe-P) generally less abundant (0–30 % total P). was predominantly organic, a relatively abundance reduced species suggests redox conditions adverse persistence bound Fe-bearing leachates. Acid ammonium-oxalate extractions suggested associated Al Fe (Al-P Fe-P) cases could be explained adsorption capacity non-crystalline (oxalate-extractable) oxides Fe. These results improve our understanding particulate vadose zone helps developing effective technologies for mitigating colloidal driven eutrophication water bodies near land.