Alcohol index reveals deep ocean secrets
Growing concern over climate change in Europe has triggered increasing interest in the North Atlantic Ocean. In turn, the Fifth Framework Programme has funded a considerable number of measurement campaigns aimed at improving our knowledge of this important body of water. One such project, entitled PACLIVA, investigated aspects of climate variability using a proxy based on hydrocarbon concentrations in cores obtained from deep sea drilling. More specifically, researchers with the Institute of Chemical and Environmental Research in Spain came up with an alcohol index (AI) that corresponds to the relative fraction of alkanes to alcohols in the sample. In addition to monitoring changes in vegetation, the Spanish scientists learned that the AI could also provide important information about deep water currents. The AI was subsequently calculated for cores from the North Atlantic (MD952011 and ENAM9606) and a core from the Gulf of Lions in the north-western Mediterranean (MD992343). The results of the analysis reveal relatively constant deep water flows in the North Atlantic since the start of the Holocene ten thousand years ago. On the contrary, deep water currents have been much more variable on the floor of the Mediterranean. For example, the AI calculated for MD992343 dropped dramatically approximately 7,300 years ago, recovered for a time but has recently started declining again. Further to the encouraging results with the AI, the Institute of Chemical and Environmental Research and its PACLIVA partners plan to employ the new proxy in future research projects.
