Radiogenic neodymium, strontium and lead isotopes of authigenic and detrital sedimentary phases and stable oxygen and carbon isotopes of benthic foraminifera from gravity cores SO213-59-2 and SO213-60-1 (central South Pacific).

The South Pacific is a sensitive location for the variability of the global oceanic thermohaline circulation given that deep waters from the Atlantic Ocean, the Southern Ocean, and the Pacific Basin are exchanged. Here we reconstruct the deep water circulation of the central South Pacific for the last two glacial cycles (from 240,000 years ago to the Holocene) based on radiogenic neodymium (Nd) and lead (Pb) isotope records complemented by benthic stable carbon data obtained from two sediment cores located on the flanks of the East Pacific Rise. The records show small but consistent glacial/interglacial changes in all three isotopic systems with interglacial average values of -5.8 and 18.757 for epsilon Nd and 206Pb/204Pb, respectively, whereas glacial averages are -5.3 and 18.744. Comparison of this variability of Circumpolar Deep Water (CDW) to previously published records along the pathway of the global thermohaline circulation is consistent with reduced admixture of North Atlantic Deep Water to CDW during cold stages. The absolute values and amplitudes of the benthic delta13C variations are essentially indistinguishable from other records of the Southern Hemisphere and confirm that the low central South Pacific sedimentation rates did not result in a significant reduction of the amplitude of any of the measured proxies. In addition, the combined detrital Nd and strontium (87Sr/86Sr) isotope signatures imply that Australian and New Zealand dust has remained the principal contributor of lithogenic material to the central South Pacific.

Polonium-210 and Lead-210 activities measured on 17 water bottle profiles and 50 surface water samples during POLARSTERN cruise ARK-XXII/2

Polonium-210 and Lead-210 have been measured in the water column and on suspended particulate matter during the POLARSTERN cruise ARK-XXII/2. The data have been submitted to Pangaea following a Polonium-Lead intercalibration exercise organized by GEOTRACES, where the AWI lab results range within the data standard deviation from 10 participating labs. Polonium-210 and Lead-210 in the ocean can be used to identify the sources and sinks of suspended matter. In seawater, Polonium-210 (210Po) and Lead-210 (210Pb) are produced by stepwise radioactive decay of Uranium-238. 210Po (138 days half life) and 210Pb (22.3 years half life) have high affinities for suspended particles. Those radionuclides are present in dissolved form and adsorbed onto particles. Following adsorption onto particle surfaces, 210Po especially is transported into the interior of cells where it bonds to proteins. In this way, 210Po also accumulates in the food chain. 210Po is therefore considered to be a good tracer for POC, and traces particle export over a timescale of month. 210Pb (22.3 years half life) adsorbs preferably onto structural components of cells, biogenic silica and lithogenic particles, and is therefore a better tracer more rapidly sinking matter. Our goal during ARK XXII/2 was to trace pathways of particulate and dissolved matter leaving the Siberian Shelf. The pathways of particulate and dissolved matter will be followed by the combined use of 210Po and 234Th as a tracer pair (and perhaps 210Pb) for particle flux (Cai, P.; Rutgers van der Loeff, MM (2008) doi:10.1594/PANGAEA.708354). This information gathered from the water column will be complemented with the results of the 210Po-210Pb study in sea ice (Camara-Mor, P, Instituto de Ciencias del Mar-SCIC, Barcelona, Spain) to provide a more thorough picture of particle transport from the shelf to the open sea and from surface to depth.

Lasting mantle scars lead to perennial plate tectonics

R.N.P. and P.J.H. are grateful for funding from an NSERC Discovery Grant. Computations were performed on the GPC supercomputer at the SciNet HPC Consortium. SciNet is funded by the Canada Foundation for Innovation under the auspices of Compute Canada, the Government of Ontario, Ontario Research Fund—Research Excellence and the University of Toronto. Numerical calculations were done using a modified version of the SOPALE (2000) software. The SOPALE modelling code was originally developed by Philippe Fullsack at Dalhousie University with Chris Beaumont and his Geodynamics group.

Climate changes, lead pollution and soil erosion in south Greenland over the past 700 years

Date of Acceptance: 05/06/2015 This research was made possible through funding provided by the Leverhulme Trust, the Spanish Ministry of Science and Innovation (Project CGL2010–20672) and Xunta de Galicia (grants R2014/001 and GPC2014/009). N Silva-Sánchez is currently supported by a FPU pre-doctoral grant (AP2010–3264) funded by the Spanish Government. Kirsty Golding, Andy McMullen, and Ian Simpson are thanked for their assistance with fieldwork. Alison Sandison produced the maps. Pete Langdon and two anonymous referees are thanked for comments that helped to improve the paper.

Climate changes, lead pollution and soil erosion in south Greenland over the past 700 years

Date of Acceptance: 05/06/2015 This research was made possible through funding provided by the Leverhulme Trust, the Spanish Ministry of Science and Innovation (Project CGL2010–20672) and Xunta de Galicia (grants R2014/001 and GPC2014/009). N Silva-Sánchez is currently supported by a FPU pre-doctoral grant (AP2010–3264) funded by the Spanish Government. Kirsty Golding, Andy McMullen, and Ian Simpson are thanked for their assistance with fieldwork. Alison Sandison produced the maps. Pete Langdon and two anonymous referees are thanked for comments that helped to improve the paper.

Climate changes, lead pollution and soil erosion in south Greenland over the past 700 years

Date of Acceptance: 05/06/2015 This research was made possible through funding provided by the Leverhulme Trust, the Spanish Ministry of Science and Innovation (Project CGL2010–20672) and Xunta de Galicia (grants R2014/001 and GPC2014/009). N Silva-Sánchez is currently supported by a FPU pre-doctoral grant (AP2010–3264) funded by the Spanish Government. Kirsty Golding, Andy McMullen, and Ian Simpson are thanked for their assistance with fieldwork. Alison Sandison produced the maps. Pete Langdon and two anonymous referees are thanked for comments that helped to improve the paper.