Lithium and rubidium concentrations in waters of seas and oceans

Data on lithium, rubidium and cesium concentrations in waters of open seas and oceans are summarized. Average amounts of these elements in the World Ocean inferred from published data and those obtained by the author are as follows: Li - 0.18 mg/l, Rb - 0.12 mg/l and Cs - 0.004 mg/l. Rare alkaline elements in the oceans and open seas are distributed (like sodium and potassium) in accordance with salinity. The ability of lithium to become a constituent of clay minerals accounts for its relatively low concentration in sea water as compared with that of sodium and potassium. Compared to rubidium and cesium that have high absorption energy and low hydration energy, lithium relatively enriches sea water. Residence times of these elements in the ocean are: Na - 120 My, Li - 2.7 My, Rb - 2.3 My and Cs - 0.3 My.

Stable isotop record of sediments across MIS 5 and Termination II

New surface water records from two high sedimentation rate sites, located in the western subtropical North Atlantic near the axis of the Gulf Stream, provide clear evidence of suborbital climate variations through marine isotope stage (MIS) 5 persisting even into the warm peak of the interglaciation (substage 5e). We found that the amplitude of suborbital climate oscillations did not vary significantly for the whole of MIS 5, implying that ice volume has little or no influence on the amplitude of suborbital climate variability in this region. Although some records suggest that longer suborbital variations (4-10 kyr) during MIS 5 are linked to deepwater changes, none of the existing records is of sufficient resolution to assess if a linkage occurred for oscillations shorter than 4 kyr. However, when examined in conjunction with published data from the Norwegian Sea, new evidence from the subpolar North Atlantic suggests that coupled surface-deepwater oscillations occurred during the penultimate deglaciation. This supports the hypothesis that during glacial and deglacial times, ocean-ice interactions and deepwater variability amplify suborbital climate change at higher latitudes. We suggest that during the penultimate deglaciation the North Atlantic deepwater source varied between Nordic Sea and open North Atlantic locations, in parallel with surface temperature oscillations.

Biomarker proxies on ODP Holes 151-912A and 151-912B

A novel and promising biomarker proxy for reconstruction of Arctic sea ice conditions was developed and is based on the determination of a highly branched isoprenoid with 25 carbons (IP25). IP25 records have been restricted to the last 150 kyr BP. We present a biomarker record from Ocean Drilling Program (ODP) Site 912, going back to the Pliocene-Pleistocene boundary and indicating that sea ice of variable extent occurred in the Fram Strait/southern Yermak Plateau area at least since about 2.2 Ma. Furthermore, our data support the idea that a combination of IP25 and open water, phytoplankton biomarker data ("PIP25 index") may give a more reliable and quantitative estimate of past sea ice cover (at least for the study area). The study reveals that the novel IP25/PIP25 biomarker approach has potential for semi-quantitative paleo-sea ice studies covering the entire Quaternary and could motivate further detailed high resolution research on ODP/IODP material using this proxy.