Five-stage sequential extractions were performed on ultramafic soil from Bosque Susua and Guanica Dry Forest, stream sediment from Rios Loco and Yauco, and nearshore sediment from Guanica Bay in southwest Puerto Rico. Sequential extractions showed partitioning of geologically enriched metals and other elements among five phases: 1) adsorbed and calcium-bound, 2) iron-, manganese-oxyhydroxide-bound