Phosphorus fractions of ornithogenic soil profiles in coral islands using P k-edge XANES, sequential extraction, and 31P-NMR spectroscopy - Xianglong Xi; Yongli Zhou; Xueying Wang; Zhangqin Zheng; Yulu Xue; Libin Wu; Liqiang Xu; Xiaodong Liu (Acta Geochimica, 2026)