not correspond to pyromorphite (Fig. 2). This implied that the fraction of PHYSICOCHEMISTRY OF LIQUIDS, P that did not leach in Garden Soil or Soil Near House did not react with SOFT MATTER, NANOCHEMISTRY Pb to form pyromorphite. The EXAFS spectra collected at the Pb LIII edge SYNCHROTRON SOLEIL HIGHLIGHTS 2020 and corresponding to the P-reacted soil samples on day 14 were treated using a PCA & Target Transformation approach. Results suggested that Pb was present as three main chemical forms in the samples, possibly as DIFFABS, LUCIA PbCO PbSO, & Pb sorbed to humic acids, based on SPOIL values. The3, 4 & SAMBA BEAMLINES spectrum corresponding to the first, second, & third principal component extracted by MCR-ALS matched with the spectrum corresponding to PbCO PbSO, & Pb sorbed to humic acids, respectively. Therefore, Associated publication 3, 4 Determining the fate of Lead (Pb) & results obtained by Target Transformation and MCR-ALS agreed with each other. Results from linear combination fitting indicated that a fraction Phosphorus (P) in alkaline Pb-polluted of Pb was still present as PbCO in Soil Near House and Soil Near Dump soils amended with P and acidified acidified with HSO on day 14 (Fig. 3). This may correspond to the3 using multiple synchrotron-based 2 4 techniques. fraction of PbCO present in large soil particles and not accessible to soil3 solution containing HSO or P. Results also indicated that a fraction of2 4 G. Landrot & S. Khaokaew. Pb was present in the three soil samples on day 14 as PbSO ins4 tead of pyromorphite, which formed only a little bit in Soil Near Dump treated Journal of Hazardous Materials, with H SO (Fig. 3). A fraction of Pb associated to humic acids was still 399: art.n° 123037 (2020). 2 4 present in Garden Soil or Soil Near House treated withHSO2 4at the end of the experiments (Fig. 3). This fraction was the most persistent in References Garden Soil, which was, among the three soil samples studied, the one [1] G. Landrot & S. Khaokaew, containing the highest SOM content (Fig. 3). Environmental Science & FIGURE 3 Technology, 52, 6780 (2018). [2] G. Landrot FASTOSH: a software to process XAFS data for geochemical & environmental applications, Goldschmidt. Goldschmidt Abstracts, Boston, p. 1402 (2018). Corresponding author Gautier Landrot Synchrotron SOLEIL, L’Orme des Merisiers, Saint Aubin, BP48, 91192 Gif-sur-Yvette Cedex, France gautier.landrot@synchrotron-soleil.fr Captions FIGURE 1: (a) μ-XRF of Soil Near Dump ; (b) μ-XRD map treated by MCR-ALS ; (c) Pb μ-XRF map vs μ-XRD MCR- ALS results. FIGURE 2: Bulk P K edge XANES corresponding to P standards and soil samples on day 0 or 14. ENVIRONMENTAL IMPLICATIONS FIGURE 3: LCF results of Pb LIII edge EXAFS Results suggested that if the P-based method is applied to stabilize corresponding to the soil samples on day 0 or 14. Pb in polluted soils, Pb should be mostly accessible to soil solution, and not significantly associated to SOM. They also indicated that fish bones should be preferentially used as P amendment instead of HPO.3 4 Indeed, the former induced less Pb & P leaching than the latter during the experiments. The lack of pyromorphite formation in Garden soil & Soil Near House could be also due to the association between P and SOM. Therefore, the results demonstrated that the inhibition of SOM on pyromorphite formation could be a double-edged sword effect as it could limit the amounts of both P & Pb in solution. 33