Abstract
Long mid-chain diols and keto-ols in SE Atlantic surface sediments have been studied in relation to the properties of the overlying surface waters. The strongest change in compound composition occurs over the Angola-Benguela Front (14–16°S). South of the front 1,13 and 1,14 diols, notably the 1,14C
28 and 1,13C
30 homologs, increase relative to 1,15 diols. The 1,13C
30 keto-ol is almost absent north of the front. These changes probably reflect differences in sea surface temperature, persistence of stratification, and upwelling at opposite sides of the front. Elevated relative abundances of the 1,15C
32 diol and 1,15C
32 keto-ol below the Congo River plume (6°S) may be outflow related, which should be tested on other river plumes. Lower relative abundances of 1,15 diols close to Walvis Bay might relate to a higher upwelling intensity compared to the other sites investigated. The applicability of the observed surface patterns is tested down core for the penultimate deglaciation. The temporal changes in diol and keto-ol composition not only have their spatial counterpart in the SE Atlantic surface sediments, they are also readily interpretable on the basis of the modern diol and keto-ol assemblages as well as the palaeoenvironmental reconstructions based on other proxies.