6 research outputs found
Temporal Variation of Iodine Isotopes in the North Sea
Monitoring temporal
variability of <sup>129</sup>I in the North
Sea, a relatively large reservoir of radioactive discharges from the
nuclear fuel reprocessing facilities, is vital for the environmental
situation in the region. New information on concentration levels and
distribution of <sup>129</sup>I and <sup>127</sup>I and their species
forms (iodide and iodate) are gained here through sampling of surface
water in 2010. The results show generally large spatial and temporal
(compared to data from 2005) fluctuations of total <sup>129</sup>I
and <sup>127</sup>I, and iodide and iodate. In samples south of 53Ā°N,
the level of <sup>127</sup>I<sup>ā</sup> in 2010 was generally
comparable or higher than in 2005. The results also show total <sup>129</sup>I concentrations comparable in the south, but 2ā8
times lower in the north, to the analyses made in 2005. Different
from total <sup>129</sup>I, the <sup>129</sup>I<sup>ā</sup>/<sup>129</sup>IO<sub>3</sub><sup>ā</sup> values in the northern
part were 2 times higher in 2010 than values observed in 2005. These
variations in total <sup>129</sup>I and <sup>127</sup>I and their
species are related to coastal water offshore propagation and surface
currents that are linked to long-term and seasonal climatic changes
over the North Atlantic and North Sea. Inventory estimation shows
that >90% of <sup>129</sup>I resides in the Southern and German
Bights,
which also suggests negligible contribution from the Sellafield facility
discharges when compared with that from the La Hague. Variability
in discharge rate from La Hague may also affect the distribution patterns
of <sup>129</sup>I in the North Sea on the monthly scale
Evaluation of Intracavity Optogalvanic Spectroscopy for Radiocarbon Measurements
Ever since the first publication
of intracavity optogalvanic spectroscopy
(ICOGS) in 2008, this novel technique for measuring the <sup>14</sup>C/<sup>12</sup>C ratio in carbon dioxide has rendered considerable
attention. As a result, there are currently at least five different
research groups pursuing research on ICOGS. With a claimed limit of
detection of 10<sup>ā15</sup> (<sup>14</sup>C/<sup>12</sup>C), i.e., in the same order as accelerator mass spectroscopy, achieved
with a relatively inexpensive and uncomplicated table-top system,
ICOGS has major scientific and commercial implications. However, during
the past 5 years, no research group has been able to reproduce these
results or present additional proof for ICOGSās capability
of unambiguous <sup>14</sup>C detection, including the authors of
the original publication. Starting in 2010, our group has set up a
state-of-the-art ICOGS laboratory and has investigated the basic methodology
of ICOGS in general and tried to reproduce the reported experiments
in particular. We have not been able to reproduce the reported results
concerning the optogalvanic signals dependence on <sup>14</sup>C concentration
and wavelength and, ultimately, not seen any evidence of the capability
of ICOGS to unambiguously detect <sup>14</sup>C at all. Instead, we
have found indications that the reported results can be products of
measurement uncertainties and mistakes. Furthermore, our results strongly
indicate that the reported limit of detection is likely to be overestimated
by at least 2 orders of magnitude, based on the results presented
in the original publication. Hence, we conclude that the original
reports on ICOGS cannot be confirmed and therefore must be in error
Iodine-129 in Snow and Seawater in the Antarctic: Level and Source
Anthropogenic <sup>129</sup>I has been released to the environment
in different ways and chemical species by human nuclear activities
since the 1940s. These sources provide ideal tools to trace the dispersion
of volatile pollutants in the atmosphere. Snow and seawater samples
collected in Bellingshausen, Amundsen, and Ross Seas in Antarctica
in 2011 were analyzed for <sup>129</sup>I and <sup>127</sup>I, including
organic forms; it was observed that <sup>129</sup>I/<sup>127</sup>I atomic ratios in the Antarctic surface seawater ((6.1ā13)
Ć 10<sup>ā12</sup>) are about 2 orders of magnitude lower
than those in the Antarctic snow ((6.8ā9.5) Ć 10<sup>ā10</sup>), but 4ā6 times higher than the prenuclear level (1.5 Ć
10<sup>ā12</sup>), indicating a predominantly anthropogenic
source of <sup>129</sup>I in the Antarctic environment. The <sup>129</sup>I level in snow in Antarctica is 2ā4 orders of magnitude lower
than that in the Northern Hemisphere, but is not significantly higher
than that observed in other sites in the Southern Hemisphere. This
feature indicates that <sup>129</sup>I in Antarctic snow mainly originates
from atmospheric nuclear weapons testing from 1945 to 1980; resuspension
and re-emission of the fallout <sup>129</sup>I in the Southern Hemisphere
maintains the <sup>129</sup>I level in the Antarctic atmosphere. <sup>129</sup>I directly released to the atmosphere and re-emitted marine
discharged <sup>129</sup>I from reprocessing plants in Europe might
not significantly disperse to Antarctica
Iodine-129 in Snow and Seawater in the Antarctic: Level and Source
Anthropogenic 129I has been released to the environment in different ways and chemical species by human nuclear activities since the 1940s. These sources provide ideal tools to trace the dispersion of volatile pollutants in the atmosphere. Snow and seawater samples collected in Bellingshausen, Amundsen, and Ross Seas in Antarctica in 2011 were analyzed for 129I and 127I, including organic forms; it was observed that 129I/127I atomic ratios in the Antarctic surface seawater ((6.1−13) × 10−12) are about 2 orders of magnitude lower than those in the Antarctic snow ((6.8−9.5) × 10−10), but 4−6 times higher than the prenuclear level (1.5 × 10−12), indicating a predominantly anthropogenic source of 129I in the Antarctic environment. The 129I level in snow in Antarctica is 2−4 orders of magnitude lower than that in the Northern Hemisphere, but is not significantly higher than that observed in other sites in the Southern Hemisphere. This feature indicates that 129I in Antarctic snow mainly originates from atmospheric nuclear weapons testing from 1945 to 1980; resuspension and re-emission of the fallout 129I in the Southern Hemisphere maintains the 129I level in the Antarctic atmosphere. 129I directly released to the atmosphere and re-emitted marine discharged 129I from reprocessing plants in Europe might not significantly disperse to Antarctica.</p