Dating of ice cores from Vernagtferner (Austria) with fission products and lead-210

Fission product (90Sr_ 90y, I37CS, total beta) and 2tOPb_210pO activities were measured in core samples from the temperate vernagtferner (3150 m altitude, Oetztal Alps, Austria). The results show that the investigated fission products are transported with water resulting from melting processes, and are sorbed on dust or dirt horizons. These products are, therefore, not suited for dating temperate glaciers. 210Pb is also transported with water and displaced from its original deposition. However, despite large fluctuations, the specific activity of 210Pb decreases with depth, and can be used to estimate accumulation rates and the age of the ice. The average annual accumulation rate amounts to about 80 cm water equivalent, and the deepest sample (81 m i. e. "" 65 m w. e.) was deposited in the beginning of this century. These results agree with data obtained from other observations on this glacier and show that the 210Pb_method is suitable to date temperate glaciers, if the ice cores cover a time interval of about 100 years (i. e. "" 4 half-lives of 210Pb). The surface activity of 210Pb was found to be 5 ± I dpm per kg of ice in agreement with other locations in the Alps and with measurements of fresh snow

Discovery of the element with atomic number 112 (IUPAC Technical Report)

The IUPAC/IUPAP Joint Working Party (JWP) on the priority of claims to the discovery of new elements has reviewed the relevant literature pertaining to several claims. In accordance with the criteria for the discovery of elements previously established by the 1992 IUPAC/IUPAP Transfermium Working Group (TWG), and reiterated by the 1999 and 2003 IUPAC/IUPAP JWPs, it was determined that the 1996 and 2002 claims by the Hofmann et al. research collaborations for the discovery of the element with atomic number 112 at Gesellschaft für Schwerionenforschung (GSI) share in the fulfillment of those criteria. A synopsis of Z = 112 experiments and related efforts is presented. A subsequent report will address identification of higher-Z elements including those of odd atomic numbe

Chemical properties of transactinides

First investigations of chemical properties of bohrium (Z = 107) and hassium (Z = 108) showed an expected behaviour as ordinary members of groups 7 and 8 of the periodic table. Two attempts to study element 112 yielded some indication for a behaviour like a very volatile noble metal. However, a very recent experiment to confirm this preliminary observation failed. Two examples are described how chemical studies may help to support element discovery claims from purely physics experiments. The two examples are the discovery claims of the elements 112 and 115, respectively, where the progenies hassium and dubnium were chemically identified

Nuclear dating

Aim: To understand the past is instrumental for predicting the future. Therefore, dating of objects – be they from human activities or from nature – is of prime interest in science. Radionuclides are themost useful tool to tackle this problem. Their half-lives may be used as a clock to measure elapsed time. However, a number of conditions have to be met for proper application of such datingmethods. Our environment is rich in radionuclides, mostly of natural origin but partly also from anthropogenic sources such as nuclear weapons testing or from nuclear accidents. This chapter summarizes applications of such radionuclides for dating purpose. Special emphasis is given to radiocarbon, 14C. Formany applications this radioisotope of carbon is the most important dating radionuclide that enables to cover time horizons from the present until about 60 000 years ago. The use of parent/daughter systems is described as well. Two other short sections address dating via stored signals in the samples from radioactive transformation. These are fission track and thermoluminescence dating

The Laboratory of Radiochemistry at Bern University and the Paul Scherrer Institute

Radiochemical research in Switzerland is pursued in a laboratory jointly financed by Bern University and the Paul Scherrer Institute. Presently, four groups – one at Bern University and three at the Paul Scherrer Institute – perform basic research in heavy element chemistry, atmospheric chemistry, paleoatmospheric studies, and geochemistry. While the first topic resembles frontier research in radiochemistry, the latter three activities involve the use of radiotracers in several environmental research fields. Most of the experiments require access to the accelerator systems and the spallation neutron source at the Paul Scherrer Institute. Some recent results of the four groups are summarized. They include the first ever chemical study of hassium (element 108), the application of the positron emitter 13N for atmospheric studies, the reconstruction of the pollution history over Europe and some radioanalytical studies with meteorites

Glacier mass balance reconstruction by sublimation induced enrichment of chemical species on Cerro Tapado (Chilean Andes)

A 36 m long ice core down to bedrock from the Cerro Tapado glacier (5536 m a.s.l, 30°08' S, 69°55' W) was analyzed to reconstruct past climatic conditions for Northern Chile. Because of the marked seasonality in the precipitation (short wet winter and extended dry summer periods) in this region, major snow ablation and related post-depositional processes occur on the glacier surface during summer periods. They include predominantly sublimation and dry deposition. Assuming that, like measured during the field campaign, the enrichment of chloride was always related to sublimation, the chemical record along the ice core may be applied to reconstruct the history of such secondary processes linked to the past climatic conditions over northern Chile. For the time period 1962–1999, a mean annual net accumulation of 316 mm water equivalent (weq) and 327 mm weq loss by sublimation was deduced by this method. This corresponds to an initial total annual accumulation of 539 mm weq. The annual variability of the accumulation and sublimation is related with the Southern Oscillation Index (SOI): higher net-accumulation during El-Niño years and more sublimation during La Niña years. The deepest part of the ice record shows a time discontinuity; with an ice body deposited under different climatic conditions: 290 mm higher precipitation but with reduced seasonal distribution (+470 mm in winter and –180 mm in summer) and –3°C lower mean annual temperature. Unfortunately, its age is unknown. The comparison with regional proxy data however let us conclude that the glacier buildup did most likely occur after the dry mid-Holocene