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Carbon-14 - DOAJ

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Last Updated: 10 January 2023

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Using helium-4, tritium, carbon-14 and other hydrogeochemical evidence to evaluate the groundwater age distribution: The case of the Neogene aquifer, Belgium

Apparent groundwater age dating has been particularly useful and reliable in determining water origins and mixing processes, especially when multiple tracers are considered. Despite being widely used, the age tracers have not been widely used in the general practice of flow and transport model calibration. In several groundwater samples, the presence of 3H, 14C, and 4He indicates that mixing of groundwater with young and old fractions occurs predominantly in the central portion of the aquifer, which is made apparent by the coexistence of 3H, 14C, and 4He. Water of different origins can also be supported by the sampled stable isotopic and hydrochemical composition of groundwater. The Particle tracking residence time results show an acceptable compromise with apparent ages derived from age tracers for young and old groundwater. Groundwater with ages ranging from 100 to 1000 years is most likely a mixture of water with young/old fractions, and it reveals the largest discrepancies between advective model ages and age tracer based on apparent ages. We can distinguish three groundwater flow systems in the Neogene aquifer based on our findings; i a shallow/local flow system with groundwater originating from modern meteoric water; i a deep/semi-regional flow system in which the presence of 4Herad is significant; ii a complex zone of groundwater flow where the newly poured meteoric water mixes with discharging old groundwater in a shallow/local flow system; ad.

Source link: https://doi.org/10.1016/j.hydroa.2022.100132


Regional Differences in Carbon-14 Data of the 993 CE Cosmic Ray Event

Although these events are characterized by a rise in cosmogenic nuclide concentrations, 14C results collected globally do not always display the same trends, particularly in 993 CE, where a dramatic rise was recorded in either 992u2013993 CE or 993u2013994 CE in several years. For the 993 CE event, we have updated 14C results of the Japanese cedar sample. Although the latest reports show no significant change in 1 year, an overall increase trend remains consistent with the previously reported 14C results of the Japanese cedar, which shows that a significant 14C rise occurred from 993 to 994 CE. High-latitude data can show 14C changes originating from SEP events more accurately and accurately than standard 14C results from tree samples from high latitude and midlatitude, including Japan, in a SEP event that was less suitable for a SEP event investigation in the past, which may be more appropriate for a SEP event investigation.

Source link: https://doi.org/10.3389/fspas.2022.886140


LIMITED OXIDATION OF IRRADIATED GRAPHITE WASTE TO REMOVE SURFACE CARBON-14

Large amounts of irradiated graphite waste from graphite-moded nuclear reactors exist and are expected to increase in the case of High Temperature Reactor construction [1,2]. This situation calls for a graphite waste collection scheme. Thermal treatment of irradiated graphite removes a substantial portion of the 14C, which tends to be concentrated on the graphite surface, as shown by study [2] [2]. Using Time of Flight Secondary Ion Mass Spectrometry and X-ray Photoelectron Spectroscopy in an attempt to properly understand the gasification process and apply the knowledge to process optimization, we investigated the amount and form of adsorbed oxygen complexes in pre- and post-irradiated graphite. Based on the predicted desorption mechanisms of carbon oxides from the identified compounds, it is predicted that the bulk of the graphite would gasify as carbon monoxide rather than carbon dioxide.

Source link: https://doi.org/10.5516/NET.06.2012.025


Reconciling the apparent absence of a Last Glacial Maximum alpine glacial advance, Yukon Territory, Canada, through cosmogenic beryllium-10 and carbon-14 measurements

Two sets of alpine glacier moraines from southern Yukon Territory, Canada's Grey Hunter massif have been found in a new in situ produced cosmogenic beryllium-10 and carbon-14 nuclide chronology. The chronology of moraines deposit by alpine glaciers outside the Last Glacial Maximum ice sheets could provide a more ambiguous account of mass balance and, eventually, climate than can be deduced from the extents of ice sheets themselves. We investigate various explanations leading to the observed differences between nuclides and find that the most parsimonious explanation for the outer moraines is one of pre-LGM deposition, but many of the sampled boulder surfaces were not exhumed from within the moraine until the Holocene.

Source link: https://doi.org/10.5194/gchron-4-311-2022


Biodegradation of Poly(butylene succinate) Powder in a Controlled Compost at 58 °C Evaluated by Naturally-Occurring Carbon 14 Amounts in Evolved CO2 Based on the ISO 14855-2 Method

Carbon dioxide measurement in a laboratory scale study was conducted using a Microbial Oxidative Degradability Analyzer based on the ISO 14855-2 system, with the ultimate aerobic biodegradability of plastic materials under controlled composting conditions. 58 b0C, J. Eu201cDetermination of the definitive aerobic biodegradability of plastic materials under monitored composting conditions. The CO2 was determined from only one reaction vessel by using the assumption that pMC was the sum of the pMC and pMC as the respective ratio in the determined period. The biodegradabilities determined by the CO2 content in the sample vessel's sample vessel were about 30% lower than those based on the ISO method.

Source link: https://doi.org/10.3390/ijms10104267


A flow-through method for scintillation counting of carbon-14 and tritium in gas-liquid chromatographic effluents

As a u201cflow-through-u201d radiation detector, a cartridge containing anthracene crystals is used as a u201c flow-throughu201d radiation detector. If tritium is to be counted, the water is reacting with hot iron to produce hydrogen and tritium gases. The sensor is easily assembled, simple to change in gas composition, but extremely sensitive to radiation. The counting rate of the cartridge is tracked continuously during the analysis by a low-background, scintillation counter to produce a record of eluted radioactivity that matches the previous mass detector record. Following the detection of a labeled compound, the counting rate returns to this low background rate.

Source link: https://doi.org/10.1016/S0022-2275(20)40412-2


Depth to water table correction for initial carbon-14 activities in groundwater mean residence time estimation

MRT results that typically assume that the unsaturated zone is in equilibrium with the atmosphere are not affected by atmospheric pressure are based on 14 C-based MRT simulations, limiting the input 14 C. Despite the availability of unsaturated zone 14 C results, no attempt has been made to generalize initial 14 C activities with depth to the water table. We use results of unsaturated zone 14 C activities from 13 studies to produce a 14 C%u2013depth relationship to estimate initial 14 C activities. The method only needs the depth to the water table at the time of sampling or an estimate of depth to water in the recharge zone to determine the input 14 C value, making it simple to apply. Owing to the simplicity of the application of the technique, this approach can be quickly integrated into existing correction schemes to determine the sensitivity of unsaturated zone 14 C to MRTs derived from 14 C results.

Source link: https://doi.org/10.5194/hess-25-5415-2021


Combination of high specific activity carbon-14 labeling and high resolution mass spectrometry to study pesticide metabolism in crops: Metabolism of cycloxaprid in rice

The study of pesticide metabolism in crops is vital in determining pesticide use and environmental risks. However, the investigation of pesticide metabolism in crops is usually complicated, and it's often a daunting challenge to accurately screen novel pesticide metabolites in a variety of matrices. The use of 14C can eliminate severe interference of complicated matrices and rapidly probe target chemicals by producing ion pairs with unique abundance ratios on HRMS and aid in the elucidation of metabolite structure. When traditional non-labeling methods are impractical, the combination of high-specificity 14C labeling and HRMS provides unique benefits and provides a cost-effective means for determining novel pesticide metabolites in complex matrices.

Source link: https://doi.org/10.1016/j.envint.2021.106879


Using carbon-14 and carbon-13 measurements for source attribution of atmospheric methane in the Athabasca oil sands region

Developing methods for evaluating suspected methane emissions is vital for designing efficient mitigation plans, but only one research has described CH4 sources in the Athabasca oil sands area. We tested the usage of 14 C and 13 C carbon isotope measurements in ambient CH 4 from the AOSR to determine source contributions from key regional CH 4 sources: tailings ponds, surface mines, and processing plants, and wetlands. The CH 4 enrichments measured at the site were mostly affected by fossil CH 4 emissions from surface mining and processing plants, followed by fossil CH 4 emissions from tailings ponds and to a lesser extent modern CH 4 emissions from wetlands, according to the isotopic signatures of ambient CH 4 enrichment. Our findings confirm the importance of tailings ponds in regional CH4 emissions and show that this technique can accurately distinguish wetland CH4 emissions.

Source link: https://doi.org/10.5194/acp-22-2121-2022


Gradual onset of the Maunder Minimum revealed by high-precision carbon-14 analyses

Abstract: The Sun has centennial-scale activity variations, including some encounters with the grand solar minimum when solar illumination becomes extremely low and sunspots disappear for several decades. However, we do still have underdeveloped knowledge of solar dynamo processes and hence accurate prediction of near-future solar activity is not achieved. It is believed that flow speed in the convection zone is a crucial measure to predict long-term solar activity variations. Solar Cycle 25's behavior can be extremely important to later solar cycles, as the Sun has shown a trend of cycle lengthening since Solar Cycle 23.

Source link: https://doi.org/10.1038/s41598-021-84830-5

* Please keep in mind that all text is summarized by machine, we do not bear any responsibility, and you should always check original source before taking any actions

* Please keep in mind that all text is summarized by machine, we do not bear any responsibility, and you should always check original source before taking any actions