Microbial biomass turnover times and clues to cellular protein repair in energy-limited deep Baltic Sea sediments.

The discovery of active microbial life deeply buried beneath the seafloor has opened important questions: how do microorganisms cope with extreme energy limitation, what is their metabolic activity, and how do they repair damages to essential biomolecules? We used a D:L-amino acid model to calculate microbial biomass turnover times. We used a metagenome and metatranscriptome analysis to investigate the distribution of the gene that encodes Protein-L-iso aspartate(D-aspartate) O-methyltransferase (PCMT), an enzyme which recognizes damaged L-isoapartyl and D-aspartyl residues in proteins and catalyzes their repair. Sediment was retrieved during the Integrated Ocean Drilling Program (IODP) Expedition 347 from Landsort Deep and the Little Belt in the Baltic Sea.

A sea-level plateau preceding the Marine Isotope Stage 2 minima revealed by Australian sediments.

Further understanding of past climate requires a robust estimate of global ice volume fluctuations that in turn rely on accurate global sea-level reconstructions. An advantage of Marine Isotope Stage 2 (MIS 2) is the availability of suitable material for radiocarbon dating to allow comparison of sea-level data with other paleoclimatic proxies. However, the number and accuracy of sea-level records during MIS 2 is currently lacking.

Exposure age and ice-sheet model constraints on Pliocene East Antarctic ice sheet dynamics.

The Late Pliocene epoch is a potential analogue for future climate in a warming world. Here we reconstruct Plio-Pleistocene East Antarctic Ice Sheet (EAIS) variability using cosmogenic nuclide exposure ages and model simulations to better understand ice sheet behaviour under such warm conditions. New and previously published exposure ages indicate interior-thickening during the Pliocene.

Larger CO₂ source at the equatorial Pacific during the last deglaciation.

While biogeochemical and physical processes in the Southern Ocean are thought to be central to atmospheric CO₂ rise during the last deglaciation, the role of the equatorial Pacific, where the largest CO₂ source exists at present, remains largely unconstrained. Here we present seawater pH and pCO₂ variations from fossil Porites corals in the mid equatorial Pacific offshore Tahiti based on a newly calibrated boron isotope paleo-pH proxy. Our new data, together with recalibrated existing data, indicate that a significant pCO₂ increase (pH decrease), accompanied by anomalously large marine (14)C reservoir ages, occurred following not only the Younger Dryas, but also Heinrich Stadial 1.