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Topics of study are genetics, biotechnology, production systems, and the interaction of agriculture with nature, among others. The programme is broadly science-based with a focus on applicability and problem-solving, and takes an integrative approach to learning about the biology behind food production. Other career possibilities include feed or supply, developing new plants, plant protection, teaching, and working with authorities to develop or enforce industry regulations. About the Degree The core of this programme is biology, with perspectives on sustainability, environmental impact, animal health and welfare, plant health, and product quality. Students can choose between specialisations including animal nutrition, plant nutrition, animal health and welfare, plant health, and pest management, or combine animal and plant sciences. Students will learn analytical and problem-solving skills, how to do research, and how to generate new knowledge.

Environmental radioactivity

Earth is constantly bombarded with primary cosmic rays , high energy charged particles — mostly protons and alpha particles. These particles interact with atoms in atmospheric gases, producing a cascade of secondary particles that may in turn interact and reduce their energies in many reactions as they pass through the atmosphere. By the time the cosmic ray cascade reaches the surface of Earth it is primarily composed of neutrons. In rock and other materials of similar density, most of the cosmic ray flux is absorbed within the first meter of exposed material in reactions that produce new isotopes called cosmogenic nuclides.

At Earth’s surface most of these nuclides are produced by neutron spallation.

Cosmogenic nuclide dating is effective over short to long timescales (1,,, years), depending on which isotope you are dating. Different isotopes are used for different lengths of times. This long period of applicability is an added advantage of cosmogenic nuclide dating.

Publications Research Goals My research interests and objectives center upon advancing the knowledge of the terrestrial record of past climate change on timescales that range from centuries to millions of years. This research will benefit our understanding of the modern climate and the mechanisms which cause climate change. I have undertaken research in various geographic locations in order to develop well-dated records of the past extents of glaciers and ice sheets.

Although my research generally involves glacial geologic studies, I have broader interests in Quaternary studies and geomorphology. Detailed field research and geomorphic mapping form the basis of my projects. I apply the surface-exposure dating method which is based on measurements of in-situ produced cosmogenic nuclides e.

Who We Are

See also Environmental radioactivity Natural Cosmogenic nuclides or cosmogenic isotopes are rare isotopes created when a high-energy cosmic ray interacts with the nucleus of an in situ solar system atom , causing cosmic ray spallation. These isotopes are produced within earth materials such as rocks or soil , in Earth’s atmosphere , and in extraterrestrial items such as meteorites. By measuring cosmogenic isotopes, scientists are able to gain insight into a range of geological and astronomical processes.

There are both radioactive and stable cosmogenic isotopes. Some of these radioisotopes are tritium , carbon and phosphorus

Although radiometric dating of ice cores has been difficult, Uranium has been used to date the Dome C ice core from Antarctica. Dust is present in ice cores, and it contains Uranium.

Publications In Preparation Goehring, B. Anomalous in situ carbon and IRSL ages on alluvial fan surfaces as a result of rapid transport from the upstream catchment. Earth and Planetary Science Letters. Coherent Holocene expansion of a tropical Andean and African glacier. Analysis of multiple cosmogenic nuclides constrains Laurentide Ice Sheet history and process on Mt. American Journal of Science. Geological Society of America Bulletin. Nuclear Instruments and Methods B.

Retreat of the western Cordilleran Ice Sheet margin during the last deglaciation. Geophysical Research Letters, 45, —

Isaac Larsen

Using cosmogenic nuclides in glacial geology Sampling strategies cosmogenic nuclide dating Difficulties in cosmogenic nuclide dating Calculating an exposure age Further Reading References Comments How can we date rocks? Geologists taking rock samples in Antarctica for cosmogenic nuclide dating. They use a hammer and chisel to sample the upper few centimetres of the rock.

Cosmogenic nuclide dating can be used to determine rates of ice-sheet thinning and recession, the ages of moraines, and the age of glacially eroded bedrock surfaces.

This characterization of the radiation is part of a physics-based complement to geological calibration of cosmogenic nuclide production rates, and should lead to better production rate estimates and better correction procedures for exposure dating and erosion-rate measurements.

October 6, Mironov56 Shutterstock Uniquely strong and light, beryllium is used to make cell phones, missiles and aircrafts. But workers who handle the metal need to watch out, as airborne beryllium has been known to be highly toxic. Named after beryllos, the Greek name for the mineral beryl, the element was originally known as glucinium — from Greek glykys, meaning “sweet” — to reflect its characteristic taste. But the chemists who discovered this unique property of beryllium also found that it is in fact highly toxic and should therefore never be tasted, according to Jefferson Lab.

In fact, the metal, its alloys and salts should only be handled in accordance with specific work codes. Beryllium is also classified as a carcinogen by the International Agency for Research on Cancer and it can cause lung cancer in people who get exposed to beryllium on a daily basis because of their occupations that require them to mine or process the metal, said Dr. Despite its toxicity, the element is highly useful because of its unique qualities.

For instance, it is one of the lightest metals and has one of the highest melting points among the light metals, according to the Los Alamos National Laboratory. Steel gray in color, beryllium’s modulus of elasticity is about one-third greater than steel.

cosmogenic-nuclide dating

Rood Published , SCEC Contribution Precariously balanced rocks PBRs are freestanding boulders that are precarious or fragile in the sense that they could be toppled by relatively low-amplitude earthquake ground motion. They are important in paleoseismology because their continued existence limits the amplitude of ground motion experienced at their location during their lifetime. In order to make quantitative use of PBRs for seismic hazard studies, one must determine when they attained their present state of fragility, that is, the point in time when the contact between the rocks and the pedestals on which they rest was exhumed from surrounding soil and the rock became vulnerable to earthquake ground motions.

Number of glaciers. From the RGI, we can learn that there are , glaciers in the World. However, this is a slightly arbitrary quantity, as it depends on the quality of the digital elevation model used, mapping resolution, and the minimum-area threshold used.

The project will develop high-resolution maps of drifts deposited from grounded marine-based ice and alpine glaciers on islands and peninsulas in McMurdo Sound. The PIs will make use of geological records for ice sheet and alpine glacier fluctuations preserved on the flanks of Mount Discovery, Black Island, and Brown Peninsula. Drifts deposited from grounded, marine-based ice will yield spatial constraints for former advances and retreats of the WAIS.

Moraines from alpine glaciers, hypothesized to be of interglacial origin, could yield a first-order record of hydrologic change in the region. Synthesizing the field data, the team proposes to improve the resolution of existing regional-scale climate models for the Ross Embayment. The overall approach and anticipated results will provide the first steps towards linking the marine and terrestrial records in this critical sector of Antarctica.

Results from the proposed work will be integrated with outreach programs at Boston University, Columbia University, and Worcester State University. The team will actively collaborate with the American Museum of Natural History to feature this project prominently in museum outreach. The geomorphological results will be presented in 3D at Boston University? The research will form the basis of a PhD dissertation at Boston University.

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Aarhus University (AU)

How do ice cores work? Current period is at right. From bottom to top: Milankovitch cycles connected to 18O. From top to bottom: Ice sheets have one particularly special property.

Production rates are almost unimaginably small – a few atoms per gram of rock per year – yet we can detect and count these “cosmogenic isotopes” using accelerator mass spectrometry, down to levels of a few thousand atoms per gram (parts per billion of parts per billion!).

Radioactive decay[ edit ] Example of a radioactive decay chain from lead Pb to lead Pb. The final decay product, lead Pb , is stable and can no longer undergo spontaneous radioactive decay. All ordinary matter is made up of combinations of chemical elements , each with its own atomic number , indicating the number of protons in the atomic nucleus.

Additionally, elements may exist in different isotopes , with each isotope of an element differing in the number of neutrons in the nucleus. A particular isotope of a particular element is called a nuclide. Some nuclides are inherently unstable. That is, at some point in time, an atom of such a nuclide will undergo radioactive decay and spontaneously transform into a different nuclide. This transformation may be accomplished in a number of different ways, including alpha decay emission of alpha particles and beta decay electron emission, positron emission, or electron capture.

Another possibility is spontaneous fission into two or more nuclides. While the moment in time at which a particular nucleus decays is unpredictable, a collection of atoms of a radioactive nuclide decays exponentially at a rate described by a parameter known as the half-life , usually given in units of years when discussing dating techniques.

Aarhus University (AU)

Purdue University Abstract Scarp morphology evolution has commonly been used to estimate the timing of fault-scarp rupture events. However, rates of scarp degradation depend strongly on the geomorphic diffusivity, a parameter that is difficult to constrain independently. This difficulty may lead to large uncertainties in the estimated ages of rupture events.

Radiometric dating or radioactive dating is a technique used to date materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they were formed. The method compares the abundance of a naturally occurring radioactive isotope within the material to the abundance of its decay products, which form at a known constant rate of decay.

Lalonde AMS Laboratory at uOttawa Timeline Preparation of accelerator mass spectrometry targets takes a minimum of one week of mineral purification and an additional week to 10 days for target chemistry. In the case of 10Be, 26Al, or 36Cl the chemistry involves ion chromotography and controlled precipitations. For the 14C extraction from quartz we use a tube furnace and flux to melt the quartz and our custom built ultrahigh vacuum stainless steel extraction line to purify the 14CO2 gas.

The wait times for accelerator mass spectrometry can be long months , during which time the required elemental analyses are also completed, either by our in-house ICP-OES or by other instruments off campus. The time for data reduction and initial interpretation ranges from a few hours to a week. Projects that involve computation with available calculators or the development of new models or theory will take longer.

Cosmogenic dating labs alecia keys dating

It ensures that inventories carried out in different places by different people are comparable. This means that we can conduct large meta-analyses of the entire dataset. The inventories should include glacier attributes, such as area, length, slope, aspect, terminal environment calving into the sea or lake, or terminating on dry land , elevation, and glacier classification.

Uniquely strong and light, beryllium is used to make cell phones, missiles and aircrafts. But workers who handle the metal need to watch out, as airborne beryllium has been known to be highly toxic.

These, and additional new magnetostratigraphic data presented here, derive from drill cores penetrating the Cold Creek flood bar in the Pasco Basin, a depositional sink for much of the material scoured from the Channeled Scabland during Missoula Floods and other similar events. The eastern part of the Cold Creek bar records a magnetostratigraphy characterized by reversed polarity at the base with normal polarity above and reversed polarity on top.

We hypothesize that the normal zone is the Jaramillo subchron 0. We test these possibilities by cosmogenic burial dating Granger and Musikar, , using the differential radioactive decay of 26Al and 10Be. We sampled 2 paleosols from drill cores of eastern Cold Creek bar as well as 14 kyr Missoula Flood sediments from Badger Coulee for cosmogenic burial dating. We chose the paleosols to increase the likelihood that sufficient cosmogenic nuclides would have accumulated in the samples prior to burial to allow application of this technique.

We analyzed the 14 kyr sample to provide an estimate of the inherited cosmogenic nuclide ratio. Measurable inherited concentrations in the same proportion as that produced at the surface would indicate that burial dating could be applied throughout the stratigraphy. If not, then only the paleosols should be dated by this technique. Initial results suggest that sufficient cosmogenic nuclides concentrations are present in these sediments to make burial dating feasible.

Cosmogenic Radionuclides

Oxygen Isotope Ratios in Carbonates At lower temperatures, calcite crystallization tends to incorporate a relatively larger proportion of 18O because the energy level vibration of ions containing this heavier isotope decreases by a greater amount than ions containing 16O. As temperatures drop, the energy level of 18O declines progressively by an amount that this disproportionately greater than that of the lighter 16O.

The equation governing this process is where Rv isotope ratio of remaining vapor, Rv isotope ratio in initial vapor, the fraction of vapor remaining and 22 Effect of Rayleigh distillation on the? Complications 1 Re-evaporation 2 Temperature dependency of? This moist air is forced into more northerly, cooler air in the northern hemisphere, where water condenses, and this condensate is enriched in 18O and D compared to the remaining vapor.

Number of glaciers. From the RGI, we can learn that there are , glaciers in the World. However, this is a slightly arbitrary quantity, as it depends on the quality of the digital elevation model used, mapping resolution, and the minimum-area threshold used.

Unlike the radioactive isotopes discussed above, these isotopes are constantly being replenished in small amounts in one of two ways. The bottom two entries, uranium and thorium , are replenished as the long-lived uranium atoms decay. These will be discussed in the next section. The other three, Carbon , beryllium , and chlorine are produced by cosmic rays–high energy particles and photons in space–as they hit the Earth’s upper atmosphere.

Very small amounts of each of these isotopes are present in the air we breathe and the water we drink. As a result, living things, both plants and animals, ingest very small amounts of carbon , and lake and sea sediments take up small amounts of beryllium and chlorine The cosmogenic dating clocks work somewhat differently than the others. Carbon in particular is used to date material such as bones, wood, cloth, paper, and other dead tissue from either plants or animals.

To a rough approximation, the ratio of carbon to the stable isotopes, carbon and carbon , is relatively constant in the atmosphere and living organisms, and has been well calibrated. Once a living thing dies, it no longer takes in carbon from food or air, and the amount of carbon starts to drop with time. Since the half-life of carbon is less than 6, years, it can only be used for dating material less than about 45, years old.

Jane Willenbring – Cosmogenic Nuclide Applications