The aim of the thesis was to decipher if and how diagenetic signals and pore profiles can be used to trace sub-recent environmental and depositional changes. The topic involves the question of how to differentiate between initial and secondary signals in marine sediments. The first part of the thesis deals with the diagenetic cycling of barium (Ba) in shallow sediment depths in the Black Sea. The results are discussed with respect to the Holocene flooding of the basin by seawater and with respect to the applicability of Ba as productivity proxy in sediments underlying a mainly anoxic water column. In a second study, sediment cores from the continental margin off Uruguay and Argentina were investigated. The respective chapters highlight the usefulness of pore water profiles for identifying and dating recent slope failure. The third main topic concerns the diagenetic cycling of phosphorus (P). Off Uruguay and Argentina, P is liberated into the pore water from the deep sediments. The release of P is linked to the reduction of iron oxides and is, thus, a consequence of high sedimentation rates.