The concn. of 19 trace elements was detd. by plasma emission spectrometry in org. fractions (org. solvent extractables, sol. humics, proto-kerogen and kerogen concs.) sepd. from various recent and ancient sediments (mangrove sediments, algal mats, oil shales, phosphorities) and sediments polluted by industrial metal emissions (Rhine River, Germany and Port Pirie, Australia). Often the org. constituents were rich in trace elements (esp. B, V, Mn, Co, Ni, Cu, Zn, As, Mo, Ag, Cd, Sb, Hg, and Pb) >=3 orders of magnitude compared to the bulk sediments, indicating the importance of org. substances with respect to transport and fixation of trace elements within sediments. The formation of metal-org. assocns. reflect the environment of deposition (marine to terrestrial) as well as diagenetic transformations (recent to ancient). Against an unpolluted natural background, increasing metal pollution led to increasing metal uptake by org. substances (esp. for B, Cr, Fe, Co, Cu, Zn, As, Cd, and Pb).