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Aldahan, Ala
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Publications (10 of 123) Show all publications
Chen, P., Yu, Z. B., Aldahan, A., Yi, P., Possnert, G. & Mugwaneza, V. d. (2017). Comparison of measurement and modeling results of the global Be-10 flux in topsoil. Journal of Radioanalytical and Nuclear Chemistry, 311(3), 2039-2045
Open this publication in new window or tab >>Comparison of measurement and modeling results of the global Be-10 flux in topsoil
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2017 (English)In: Journal of Radioanalytical and Nuclear Chemistry, ISSN 0236-5731, E-ISSN 1588-2780, Vol. 311, no 3, p. 2039-2045Article in journal (Refereed) Published
Abstract [en]

Soils are among the major terrestrial reservoirs of atmospheric Be-10 isotope and provide information of landscape evolution history. Despite this importance, there is no overview of the global soil Be-10 fluxes in topsoil that is linked with atmospheric flux models. A comparison between measured (in topsoil) and atmospherically modeled Be-10 fluxes is presented here. The data show relatively good agreement in the latitudinal trends. This feature demonstrates the potential to use the modeling data in estimating soil development/erosion rates in large scale basins where extensive Be-10 measurements can be limited.

Place, publisher, year, edition, pages
Springer, 2017
Keyword
Be-10 flux, Atmosphere, Global, Landscape, Topsoil
National Category
Physical Geography
Identifiers
urn:nbn:se:uu:diva-320282 (URN)10.1007/s10967-017-5171-8 (DOI)000398027800055 ()
Available from: 2017-04-25 Created: 2017-04-25 Last updated: 2018-01-13Bibliographically approved
Xing, S., Hou, X., Aldahan, A. & Possnert, G. (2017). Speciation analysis of I-129 in seawater using coprecipitation and accelerator mass spectrometry and its applications. Journal of Radioanalytical and Nuclear Chemistry, 311(1), 833-841
Open this publication in new window or tab >>Speciation analysis of I-129 in seawater using coprecipitation and accelerator mass spectrometry and its applications
2017 (English)In: Journal of Radioanalytical and Nuclear Chemistry, ISSN 0236-5731, E-ISSN 1588-2780, Vol. 311, no 1, p. 833-841Article in journal (Refereed) Published
Abstract [en]

Speciation analysis of long-lived I-129 in seawater can provide useful information on the source of water masses. This paper presents an improved method for speciation analysis of I-129 based on coprecipitation of iodide as AgI with Ag2SO3 and AgCl. By adding a small amount of I-127 carrier, the separation efficiency of iodine species and the accuracy and precision of I-129 measurement are remarkably improved. I-129 species in depth profiles of seawater from the Antarctic were analyzed for investigation of water circulation in the Antarctic.

Keyword
I-129, Speciation analysis, Accelerator mass spectrometry, Seawater
National Category
Analytical Chemistry
Identifiers
urn:nbn:se:uu:diva-315844 (URN)10.1007/s10967-016-5060-6 (DOI)000392075200089 ()
Funder
Swedish Polar Research Secretariat
Available from: 2017-02-21 Created: 2017-02-21 Last updated: 2017-11-29Bibliographically approved
Xing, S., Hou, X., Aldahan, A., Possnert, G., Shi, K., Yi, P. & Zhou, W. (2017). Water Circulation and Marine Environment in the Antarctic Traced by Speciation of I-129 and I-127. Scientific Reports, 7, Article ID 7726.
Open this publication in new window or tab >>Water Circulation and Marine Environment in the Antarctic Traced by Speciation of I-129 and I-127
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2017 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 7726Article in journal (Refereed) Published
Abstract [en]

Emissions of anthropogenic I-129 from human nuclear activities are now detected in the surface water of the Antarctic seas. Surface seawater samples from the Drake Passage, Bellingshausen, Amundsen, and Ross Seas were analyzed for total I-129 and I-127, as well as for iodide and iodate of these two isotopes. The variability of I-127 and I-129 concentrations and their species (I-127(-)/(IO3-)-I-127, I-129(-)/(IO3-)-I-129) suggest limited environmental impact where ((1.15-3.15) x 10(6) atoms/L for I-129 concentration and (0.61-1.98) x 10(-11) for I-129/I-127 atomic ratios are the lowest ones compared to the other oceans. The iodine distribution patterns provide useful information on surface water transport and mixing that are vital for better understanding of the Southern Oceans effects on the global climate change. The results indicate multiple spatial interactions between the Antarctic Circumpolar Current (ACC) and Antarctic Peninsula Coastal Current (APCC). These interactions happen in restricted circulation pathways that may partly relate to glacial melting and icebergs transport. Biological activity during the warm season should be one of the key factors controlling the reduction of iodate in the coastal water in the Antarctic.

Place, publisher, year, edition, pages
Nature Publishing Group, 2017
National Category
Oceanography, Hydrology and Water Resources
Identifiers
urn:nbn:se:uu:diva-334040 (URN)10.1038/s41598-017-07765-w (DOI)000407400100013 ()28798296 (PubMedID)
Available from: 2017-11-22 Created: 2017-11-22 Last updated: 2018-01-13Bibliographically approved
Czymzik, M., Adolphi, F., Muscheler, R., Mekhaldi, F., Martin-Puertas, C., Aldahan, A., . . . Brauer, A. (2016). A varved lake sediment record of the Be-10 solar activity proxy for the Lateglacial-Holocene transition. Quaternary Science Reviews, 153, 31-39
Open this publication in new window or tab >>A varved lake sediment record of the Be-10 solar activity proxy for the Lateglacial-Holocene transition
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2016 (English)In: Quaternary Science Reviews, ISSN 0277-3791, E-ISSN 1873-457X, Vol. 153, p. 31-39Article in journal (Refereed) Published
Abstract [en]

Solar modulated variations in cosmogenic radionuclide production provide both information on past changes in the activity of the Sun and a global synchronization tool. However, to date the use of cosmogenic radionuclides for these applications is almost exclusively based on Be-10 records from ice cores and C-14 time-series from tree rings, all including archive-specific limitations. We present the first Be-10 record from annually laminated (varved) lake sediments for the Lateglacial-Holocene transition from Meerfelder Maar. We quantify environmental influences on the catchment and, consequently, Be-10 deposition using a new approach based on regression analyses between our Be-10 record and environmental proxy time-series from the same archive. Our analyses suggest that environmental influences contribute to up to 37% of the variability in our Be-10 record, but cannot be the main explanation for major Be-10 excursions. Corrected for these environmental influences, our Be-10 record is interpreted to dominantly reflect changes in solar modulated cosmogenic radionuclide production. The preservation of a solar production signal in Be-10 from varved lake sediments highlights the largely unexplored potential of these archives for solar activity reconstruction, as global synchronization tool and, thus, for more robust paleoclimate studies.

Keyword
Be-10, Varved lake sediments, Solar activity, Time-scales
National Category
Geophysics
Identifiers
urn:nbn:se:uu:diva-311500 (URN)10.1016/j.quascirev.2016.10.007 (DOI)000389116000003 ()
Funder
German Research Foundation (DFG), CZ 227/1-1Swedish Research Council, 2013-8421
Available from: 2016-12-28 Created: 2016-12-28 Last updated: 2017-11-29Bibliographically approved
Sturevik-Storm, A., Aldahan, A., Possnert, G., Berggren, A.-M., Muscheler, R., Dahl-Jensen, D., . . . Usoskin, I. (2014). Be-10 climate fingerprints during the Eemian in the NEEM ice core, Greenland. Scientific Reports, 4, 6408
Open this publication in new window or tab >>Be-10 climate fingerprints during the Eemian in the NEEM ice core, Greenland
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2014 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 4, p. 6408-Article in journal (Refereed) Published
Abstract [en]

Several deep Greenland ice cores have been retrieved, however, capturing the Eemian period has been problematic due to stratigraphic disturbances in the ice. The new Greenland deep ice core from the NEEM site (77.456 degrees N, 51.066 degrees W, 2450 m.a.s.l) recovered a relatively complete Eemian record. Here we discuss the cosmogenic Be-10 isotope record from this core. The results show Eemian average 10Be concentrations about 0.7 times lower than in the Holocene which suggests a warmer climate and approximately 65-90% higher precipitation in Northern Greenland compared to today. Effects of shorter solar variations on 10Be concentration are smoothed out due to coarse time resolution, but occurrence of a solar maximum at 115.26-115.36 kyr BP is proposed. Relatively high 10Be concentrations are found in the basal ice sections of the core which may originate from the glacial-interglacial transition and relate to a geomagnetic excursion about 200 kyr BP.

National Category
Geosciences, Multidisciplinary
Identifiers
urn:nbn:se:uu:diva-235323 (URN)10.1038/srep06408 (DOI)000342448600001 ()
Available from: 2014-11-05 Created: 2014-10-30 Last updated: 2017-12-05Bibliographically approved
Murad, A., Zhou, X. D., Yi, P., Alshamsi, D., Aldahan, A., Hou, X. L. & Yu, Z. B. (2014). Natural radioactivity in groundwater from the south-eastern Arabian Peninsula and environmental implications. Environmental Monitoring & Assessment, 186(10), 6157-6167
Open this publication in new window or tab >>Natural radioactivity in groundwater from the south-eastern Arabian Peninsula and environmental implications
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2014 (English)In: Environmental Monitoring & Assessment, ISSN 0167-6369, E-ISSN 1573-2959, Vol. 186, no 10, p. 6157-6167Article in journal (Refereed) Published
Abstract [en]

Groundwater is the most valuable resource in arid regions, and recognizing radiological criteria among other water quality parameters is essential for sustainable use. In the investigation presented here, gross-alpha and gross-beta were measured in groundwater samples collected in the south-eastern Arabian Peninsula, 67 wells in Unite Arab Emirates (UAE), as well as two wells and one spring in Oman. The results show a wide gross-alpha and gross-beta activities range in the groundwater samples that vary at 0.01 similar to 19.5 Bq/l and 0.13 similar to 6.6 Bq/l, respectively. The data show gross-beta and gross-alpha values below the WHO permissible limits for drinking water in the majority of the investigated samples except those in region 4 (Jabel Hafit and surroundings). No correlation between groundwater pH and the gross-alpha and gross-beta, while high temperatures probably enhance leaching of radionuclides from the aquifer body and thereby increase the radioactivity in the groundwater. This conclusion is also supported by the positive correlation between radioactivity and amount of total dissolved solid. Particular water purification technology and environmental impact assessments are essential for sustainable and secure use of the groundwater in regions that show radioactivity values far above the WHO permissible limit for drinking water.

Keyword
Gross alpha, Gross beta, Groundwater, Radioactivity, UAE
National Category
Ecology
Identifiers
urn:nbn:se:uu:diva-234139 (URN)10.1007/s10661-014-3846-y (DOI)000341497800015 ()
Available from: 2014-10-20 Created: 2014-10-14 Last updated: 2017-12-05Bibliographically approved
Aldahan, A., Possnert, G., El Saiy, A. & Abdelghany, O. (2014). Particle-bound Be-10 from a low latitude arid region. Journal of Radioanalytical and Nuclear Chemistry, 299(3), 1709-1713
Open this publication in new window or tab >>Particle-bound Be-10 from a low latitude arid region
2014 (English)In: Journal of Radioanalytical and Nuclear Chemistry, ISSN 0236-5731, E-ISSN 1588-2780, Vol. 299, no 3, p. 1709-1713Article in journal (Refereed) Published
Abstract [en]

The Be-10 isotope is widely used in geochronology, climate and environmental analyses and astrophysics where atmospheric deposition model estimate plays a vital role for the initial concentration. Data from arid regions have not been well constrained because of sparse measurement and here we present Be-10 concentration in samples of dust, soil, marine sediments and paleosol collected from an arid to semi-arid low latitude region. These results indicate concentrations that are about a factor of three lower than values expected from latitude zonal models, but are comparable with global atmospheric depositional model. The agreement and discrepancy between model and measured data are rather vital for establishing accurate initial Be-10 in the Earth's surface environment for reconstruction of paleoclimatic variability (precipitation rates and temperature).

Keyword
Be-10, Arid regions, Dust, Soil, UAE
National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-222752 (URN)10.1007/s10967-013-2853-8 (DOI)000332034400071 ()
Available from: 2014-04-14 Created: 2014-04-14 Last updated: 2017-12-05Bibliographically approved
He, P., Hou, X., Aldahan, A. & Possnert, G. (2014). Radioactive I-129 in surface water of the Celtic Sea. Journal of Radioanalytical and Nuclear Chemistry, 299(1), 249-253
Open this publication in new window or tab >>Radioactive I-129 in surface water of the Celtic Sea
2014 (English)In: Journal of Radioanalytical and Nuclear Chemistry, ISSN 0236-5731, E-ISSN 1588-2780, Vol. 299, no 1, p. 249-253Article in journal (Refereed) Published
Abstract [en]

Relatively large amounts of radioactive iodine 129I (T 1/2  = 15.7 Ma) have been documented in seawater such as the English Channel, the Irish Sea and the North Sea. Data on the concentration of the iodine isotopes in waters of the Celtic Sea are missing. Aiming to provide first 129I data in the Celtic Sea and compare them with levels in the other close-by seawater bodies, surface seawater samples were analyzed for the determination of 127I and 129I concentrations. The results revealed a high level of 129I in these waters and suggest strong influence by liquid discharges from La Hague and Sellafield reprocessing facilities. 127I concentrations are rather constant while the 129I/127I ratio reaches up to 2.8 × 10−8 (ranging from 10−10 to 10−8), which is 2–4 orders of magnitude higher than pre-nuclear era natural level. Transport of 129I to the Celtic Sea is difficult to depict accurately since available data are sparse. Most likely, however, that discharges originated from La Hague may have more influence on the Celtic Sea 129I concentrations than the Sellafield. Comprehensive surface water and depth profiles 129I data will be needed in the future for assessment of environmental impact in the region.

Keyword
Iodine, I-129, Celtic Sea, Nuclear reprocessing facilities
National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-218588 (URN)10.1007/s10967-013-2792-4 (DOI)000329299200033 ()
Available from: 2014-02-13 Created: 2014-02-13 Last updated: 2017-12-06Bibliographically approved
Murad, A., Alshamsi, D., Hou, X. L., Al Shidi, F., Al Kendi, R. & Aldahan, A. (2014). Radioactivity in groundwater along the borders of Oman and UAE. Journal of Radioanalytical and Nuclear Chemistry, 299(3), 1653-1660
Open this publication in new window or tab >>Radioactivity in groundwater along the borders of Oman and UAE
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2014 (English)In: Journal of Radioanalytical and Nuclear Chemistry, ISSN 0236-5731, E-ISSN 1588-2780, Vol. 299, no 3, p. 1653-1660Article in journal (Refereed) Published
Abstract [en]

Characterizing the quality and radioactivity of groundwater is vital as it represents valuable resource in arid regions. Here we present radioactivity level in groundwater collected from wells in a region along the border between Sultanate of Oman and United Arab Emirates (UAE). The aquifers are alluvium deposits (silt, sand and gravel) and the measured groundwater radioactivity (including Th-232, U-238, U-235, Ra-226, Rn-222, gross-alpha and gross-beta) indicates values below the WHO permissible limits for drinking water. The results also show large difference in radioactivity fingerprints, in particular for Ra-226 and Rn-222 within the investigated aquifers. The data further indicate lower radioactivity in groundwater of the alluviums compared to the carbonate aquifers in the region. This feature makes the alluvium aquifers valuable reservoirs that should be carefully exploited as a source of groundwater. As this is the first investigation on the radioactivity of groundwater in alluvial aquifers in the region, it suggests that other alluvial deposits, particularly those inland and far from the marine water intrusion or seepage from carbonate rocks would have low radioactivity fingerprints.

Keyword
Groundwater, Radioactivity, Alluvial, Oman, UAE
National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-222751 (URN)10.1007/s10967-013-2911-2 (DOI)000332034400064 ()
Available from: 2014-04-14 Created: 2014-04-14 Last updated: 2017-12-05Bibliographically approved
He, P., Aldahan, A., Possnert, G. & Hou, X. (2014). Temporal variation of iodine isotopes in the North Sea. Environmental Science and Technology, 48(3), 1419-1425
Open this publication in new window or tab >>Temporal variation of iodine isotopes in the North Sea
2014 (English)In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 48, no 3, p. 1419-1425Article in journal (Refereed) Published
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:uu:diva-206705 (URN)10.1021/es402047s (DOI)000331015100010 ()
Available from: 2013-09-03 Created: 2013-09-03 Last updated: 2017-12-06Bibliographically approved
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