Radiocarbon age determination of 16 sites

The thermal diffusion enrichment apparatus in use in Amsterdam before 1967, has been rebuilt in the Groningen Radiocarbon Dating Laboratory. It has been shown to operate reliably and reproducibly. A reasonable agreement exists between the theoretical calculations and the experimental results. The 14C enrichment of a CO sample is deduced from the simultaneous mass 30 enrichment, which is measured with a mass spectrometer. The relation between both enrichments follows from a series of calibration measurements. The over-all accuracy in the enrichment is a few percent, equivalent to a few hundred years in age. The main problem in dating very old samples is their possible contamination with recent carbon. Generally, careful sample selection and rigorous pretreatment reduce sample contamination to an acceptable value. Also, it has been established that laboratory contamination, due to a memory effect in the combustion system and to impurities in the oxygen and nitrogen gas used for combustion, can be eliminated. A detailed analysis shows that the counter background in our set-up is almost exclusively caused by cosmic ray muons. The measurement of 28 early glacial samples, mostly from North-west Europe, has yielded a consistent set of ages. These indicate the existence of three early glacial interstadials; using the Weichselian definitions: Amersfoort starting at 68 200 ± 1100, Brørup at 64 400 ± 800 and Odderade at 60 500 ± 600 years BP. This 14C chronology shows good agreement with the Camp Century chronology and the dated palaeo sea levels. The discrepancy in the age of the early part of the Last Glacial on the 14C time scale and on that adopted for the deep-sea d18 record, must probably be attributed to the use of a generalized d18 curve and a wrong interpretation of this curve in terms of three Barbados terraces.

Climate sensitivity across marine domains of life: limits to evolutionary adaptation shape species interactions, supplementary material

Organisms in all domains, Archaea, Bacteria, and Eukarya will respond to climate change with differential vulnerabilities resulting in shifts in species distribution, coexistence, and interactions. The identification of unifying principles of organism functioning across all domains would facilitate a cause and effect understanding of such changes and their implications for ecosystem shifts. For example, the functional specialization of all organisms in limited temperature ranges leads us to ask for unifying functional reasons. Organisms also specialize in either anoxic or various oxygen ranges, with animals and plants depending on high oxygen levels. Here, we identify thermal ranges, heat limits of growth, and critically low (hypoxic) oxygen concentrations as proxies of tolerance in a meta-analysis of data available for marine organisms, with special reference to domain-specific limits. For an explanation of the patterns and differences observed, we define and quantify a proxy for organismic complexity across species from all domains. Rising complexity causes heat (and hypoxia) tolerances to decrease from Archaea to Bacteria to uni- and then multicellular Eukarya. Within and across domains, taxon-specific tolerance limits likely reflect ultimate evolutionary limits of its species to acclimatization and adaptation. We hypothesize that rising taxon-specific complexities in structure and function constrain organisms to narrower environmental ranges. Low complexity as in Archaea and some Bacteria provide life options in extreme environments. In the warmest oceans, temperature maxima reach and will surpass the permanent limits to the existence of multicellular animals, plants and unicellular phytoplankter. Smaller, less complex unicellular Eukarya, Bacteria, and Archaea will thus benefit and predominate even more in a future, warmer, and hypoxic ocean.

Permafrost cores and active layer pits on Herschel Island: link to shape files

Twelve permafrost cores and active layer pits were drilled/dug on Herschel Island in order to estimate the soil organic carbon and total nitrogen contents in the first 30, 100 and 200 cm of ground. The data are shapefile points with attribute table, which contains different core information.