| 1. |
- Alakangas, Linda J., et al.
(författare)
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Sampling and Characterizing Rare Earth Elements in Groundwater in Deep-Lying Fractures in Granitoids Under In Situ High-Pressure and Low-Redox Conditions
- 2014
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Ingår i: Aquatic geochemistry. - : Springer Science and Business Media LLC. - 1380-6165 .- 1573-1421. ; 20:4, s. 405-418
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Tidskriftsartikel (refereegranskat)abstract
- Several countries are preparing to dispose of radioactive nuclear waste deep underground in crystalline rock. This type of bedrock is commonly extensively fractured and consequently carries groundwater that serves as a medium for transporting metals and radionuclides. A group of metals of particular interest in this context is the rare earth elements (REEs), because they are analogues of actinides contained within radioactive waste and are tracers of hydrological pathways and geochemical processes. Concentrations of REEs are commonly low in these groundwaters, leading to values below detection limits of standard monitoring methods, particularly for the heavy REEs. We present a new technical set-up for monitoring REEs (and other trace metals) in groundwater in fractured crystalline rock. The technique consists of passing the fracture groundwater, commonly under high pressure and containing reduced chemical species, through a device that maintains the physicochemical character of the groundwater. Within the device, diffusive gradient in thin-film (DGT) discs are installed in triplicate. With this set-up, we studied REEs in groundwater in fractures at depths of approximately -144, -280, and -450 m in granitoids in the A"spo Hard Rock Laboratory in southern Sweden. The entire REE suite was detected (concentrations down to 0.1 ng L-1) and was differently fractionated among the groundwaters. The shallowest groundwater, composed of dilute modern Baltic Sea water, was enriched in the heavy REEs, whereas the deeper groundwaters, dominated by old saline water, were depleted in the heavy REEs. Deployment periods varying from 1 to 4 weeks delivered similar REE concentrations, indicating stability and reproducibility of the experimental set-up. The study finds that 1 week of deployment may be enough. However, if the overall setting and construction allow for longer deployment times, 2-3 weeks will be optimal in terms of reaching reliable REE concentrations well above the detection limit while maintaining the performance of the DGT samplers.
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| 2. |
- Baxter, Douglas, et al.
(författare)
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Serum/plasma methylmercury determination by isotope dilution gas chromatography : inductively coupled plasma mass spectrometry
- 2011
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Ingår i: Analytica Chimica Acta. - : Elsevier BV. - 0003-2670 .- 1873-4324. ; 701:2, s. 134-138
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Tidskriftsartikel (refereegranskat)abstract
- A method for the determination of methylmercury in plasma and serum samples was developed. The method uses isotope dilution with 198Hg-labelled methylmercury, extraction into dichloromethane, back-extraction into water, aqueous-phase ethylation, purge and trap collection, thermal desorption, separation by gas chromatography, and mercury isotope specific detection by inductively coupled plasma mass spectrometry. By spiking 2 mL sample with 1.2 ng tracer, measurements in a concentration interval of (0.007–2.9) μg L−1 could be performed with uncertainty amplification factors <2. A limit of quantification of 0.03 μg L−1 was estimated at 10 times the standard deviation of concentrations measured in preparation blanks. Within- and between-run relative standard deviations were <10% at added concentration levels of 0.14 μg L−1, 0.35 μg L−1 and 2.8 μg L−1, with recoveries in the range 82% to 110%. Application of the method to 50 plasma/serum samples yielded a median (mean; range) concentration of methylmercury of 0.081 (0.091; <0.03–0.19) μg L−1. This is the first time methylmercury has been directly measured in this kind of specimen, and is therefore the first estimate of a reference range.
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| 3. |
- Faarinen, Mikko, et al.
(författare)
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Al-26 at the AMS facility in Lund
- 2004
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms. - : Elsevier BV. - 0168-583X. ; 223-24, s. 130-134
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Tidskriftsartikel (refereegranskat)abstract
- To broaden the AMS programme in Lund by including Al studies, a new injector has been installed and tested at the 3 MV Pelletron accelerator. Detailed optical calculations have been performed to obtain maximum mass and energy resolution. The design of the injector, the improvement in the resolution compared to the old injector, as well as preliminary tests with a Al-26-beam, are presented. By using accelerator mass spectrometry (AMS) to measure the long-lived aluminium isotope Al-26 it has become possible to study the uptake, distribution and retention of aluminium in biological system under physiologically realistic conditions. Results from a pilot project on Al-26 in wheat plants are presented.
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| 4. |
- Faarinen, Mikko
(författare)
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Development of the Lund AMS facility for the detection of Al-26 -- with applications in plant ecology
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Accelerator mass spectrometry (AMS) is a highly sensitive technique to count atoms. The method has a high efficiency, which makes it possible to measure small samples in a relatively short time, usually less than an hour. During the work for this thesis, methods have been developed to detect Al-26 at the Lund AMS facility. This includes the design, installation and testing of a new injector that is used mainly for Al-26 ions with the Pelletron accelerator at the Department of Physics, Lund. Al-26 is rare in nature and, as the natural background can therefore be ignored, well suited for tracer measurements. The long half life, 717 000 year, makes it difficult to measure Al-26 by conventional decay counting but is well suited for AMS measurements. A new, high resolution, 90°-injector has been installed in addition to the existing 15°-injector. The low mass resolution of the old 15°-injector allowed energy tails from MgH to pass the injector and, after being split during the stripping process, Mg-26 is able to enter the detector. This is the limiting factor for Al-26 measurements with the 15°-injector. For the new injector high quality energy- and mass-resolution is obtained by a 90° electrostatic energy analyser combined with a 90° magnetic mass analyser. Results of Al-26 measurements with the existing 15°-injector as well as with the new 90°-injector are presented. This injector has a more than ten times better resolution than the old 15°-injector. The new injector has proven to efficiently remove the troublesome isobar Al-26. Methods for preparing aluminium samples for the AMS ion source have been developed, both for chemically pure samples as well as for plant samples. The samples are dissolved in an acid to insure a homogeneous mixture of the Al-26 from the sample and the added Al-27 carrier. By heating the samples the Al is oxidised to Al2O3, which is a suitable material for AMS samples. As the amount of carrier is known, the content of Al-26 can be calculated. Plant samples have been grown in a controlled Al-26 environment with different levels of Ca or (Mg + K), in addition to 100 uM of Al-27, to investigate Al uptake. After one week of growth the Al-26 levels were measured with AMS. The concentration in the plants was found to be considerable, but did not differ between the treatments.
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| 5. |
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| 6. |
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| 7. |
- Hellborg, Ragnar, et al.
(författare)
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A high resolution AMS-injector for the Pelletron in Lund
- 2002
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Ingår i: Pramana. - 0973-7111. ; 59:6, s. 1061-1073
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Tidskriftsartikel (refereegranskat)abstract
- A high resolution injector system has recently been installed at the Lund 3 MV tandem Pelletron accelerator. The new injector, designed mainly for Al-26 ions, will increase the experimental potential of the Lund AMS facility considerably. High quality energy- and mass-resolution is obtained by using a 90degrees spherical electrostatic analyzer followed by a 90degrees magnetic analyzer. The injector is equipped with a high intensity sputtering source with a spherical ionizer. A new analytical technique for acceptance calculations as well as PC-based computational methods have been used in the design of the ion optical system of the new injector. Compared to our old injector system which has a magnetic analyzer with a bending angle of only 15degrees, the new system has a more than ten times better resolution. The beam optics of the new system is also better designed to match the accelerator acceptance. In this way the ion transmission from the ion source to the detector, for different ions of interest in our AMS programme, has been increased.
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| 8. |
- Hellborg, Ragnar, et al.
(författare)
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Accelerator mass spectrometry
- 2003
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Ingår i: Romanian Journal of Physics. - 1221-146X. ; 48:1-4, s. 27-37
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Konferensbidrag (refereegranskat)abstract
- Accelerator mass spectrometry (AMS) is a world-wide spread technique and nearly 50 AMS laboratories exist today. The most widely spread application of AMS is for radiocarbon dating and an estimated total of nearly 100000 14C samples are measured per year. Other isotopes used are 10Be, 26Al, 36Cl, 41Ca, 129I. The number of these measured per year is estimated to be 10% of the number of 14C samples or even less
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| 9. |
- Hellborg, Ragnar, et al.
(författare)
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Accelerator mass spectrometry - an overview
- 2003
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Ingår i: Vacuum. - 0042-207X. ; 70:2-3, s. 365-372
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Tidskriftsartikel (refereegranskat)abstract
- The technique of accelerator mass spectrometry (AMS) has spread worldwide since its first demonstration 25 years ago. The equipment used today is very diverse and dedicated accelerators as well as old "nuclear physics machines" can be found in the nearly 50 AMS laboratories today. The most widely spread application of AMS is for radiocarbon dating. However, AMS with C-14 as well as with other long-lived isotopes have also found applications in many other fields in physics and beyond.
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| 10. |
- Hellborg, Ragnar, et al.
(författare)
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Mechanical design of the recirculating, terminal pumping in the Lund Pelletron, and experimental experience
- 2002
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Ingår i: Pramana - Journal of Physics. - 0304-4289 .- 0973-7111. ; 59:5, s. 725-737
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Konferensbidrag (refereegranskat)abstract
- A recirculating terminal pumping system has been installed in the 3 MV Pelletron tandem accelerator in Lund. An extremly limited space in the high voltage terminal and the absence of electrical power in the terminal, forced us to provide a unique design for the installation and powering of the new pumps. Details of the technical design, as well as experience of the use of the new system for accelerator mass Spectrometry, will be given.
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