Speciation analysis of 129I in seawater using coprecipitationand accelerator mass spectrometry and its applications

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

Uranium isotopes in carbonate aquifers of arid region setting

Groundwater in arid and semiarid regions is vital resource for many uses and therefore information about concentrations of uranium isotopes among other chemical parameters are necessary. In the study presented here, distribution of U-238 and U-235 in groundwater of four selected locations in the southern Arabian peninsula, namely at two locations within the United Arab Emirates (UAE) and two locations in Oman are discussed. The analyses of the uranium isotopes were performed using ICP-MS and the results indicated a range of concentrations for U-235 and (238) U at 3-39 ng L-1 (average: 18 ng L-1) and 429-5,293 ng L-1 (average: 2,508 ng L-1) respectively. These uranium concentrations are below the higher permissible WHO limit for drinking water and also comparable to averages found in groundwater from similar aquifers in Florida and Tunisia. Negative correlation between rainfall and uranium concentrations suggests that in lithologically comparable aquifers, climate may influence the concentration of uranium in subtropical to arid regions.</p

Tracing variability in the iodine isotopes and species along surfacewater transect from the North Sea to the Canary Islands

A complete transect of surface water samples from the North Sea to the Canary Islands was collected during a continuous period in 2010. The samples were analyzed for total 129I and 127I isotopes and their iodide and iodate species. The results indicate a large variability in the total 129I and its species along the transect, whereas less change and variation are observed for the total 127I and its species. Transport of 129I from the western English Channel via Biscay Bay is the main source of 129I in the northeastern Atlantic Ocean.</p

Iodine isotopes species fingerprinting environmental conditions in surface water along the northeastern Atlantic Ocean

Concentrations and species of iodine isotopes (I-127 and I-129) provide vital information about iodine geochemistry, environmental conditions and water masses exchange in oceans. Despite extensive investigations of anthropogenic I-129 in the Arctic Ocean and the Nordic Seas, concentrations of the isotope in the Atlantic Ocean are, however, still unknown. We here present first data on I-129 and I-127, and their species (iodide and iodate) in surface water transect along the northeastern Atlantic between 30 degrees and 50 degrees N. The results show iodate as the predominant species in the analyzed marine waters for both I-127 and I-129. Despite the rather constant ratios of I-127(-)/(IO3-)-I-127, the I-129(-)/(IO3-)-I-129 values reveal variations that apparently response to sources, environmental conditions and residence time. These findings provide a new tracer approach that will strongly enhance the application of anthropogenic I-129 in ocean environments and impact on climate at the ocean boundary layer.</p

Water Circulation and MarineEnvironment in the Antarctic Tracedby Speciation of 129I and 127I

Emissions of anthropogenic &sup1;&sup2;⁹I 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 &sup1;&sup2;⁹I and &sup1;&sup2;⁷I, as well as for iodide and iodate of these two isotopes. The variability of &sup1;&sup2;⁷I and &sup1;&sup2;⁹I concentrations and their species (&sup1;&sup2;⁷I⁻/&sup1;&sup2;⁷IO3⁻, &sup1;&sup2;⁹I⁻/&sup1;&sup2;⁹IO3⁻) suggest limited environmental impact where ((1.15&ndash;3.15) &times; 10⁶ atoms/L for &sup1;&sup2;⁹I concentration and (0.61&ndash;1.98) &times; 10⁻&sup1;&sup1; for &sup1;&sup2;⁹I/&sup1;&sup2;⁷I 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

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&minus;13) &times; 10&minus;12) are about 2 orders of magnitude lower than those in the Antarctic snow ((6.8&minus;9.5) &times; 10&minus;10), but 4&minus;6 times higher than the prenuclear level (1.5 &times; 10&minus;12), indicating a predominantly anthropogenic source of 129I in the Antarctic environment. The 129I level in snow in Antarctica is 2&minus;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

Radioactive ¹²⁹I in surface water of the Celtic Sea

Relatively large amounts of radioactive iodine I-129 (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 I-129 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 I-127 and I-129 concentrations. The results revealed a high level of I-129 in these waters and suggest strong influence by liquid discharges from La Hague and Sellafield reprocessing facilities. I-127 concentrations are rather constant while the I-129/I-127 ratio reaches up to 2.8 x 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 I-129 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 I-129 concentrations than the Sellafield. Comprehensive surface water and depth profiles I-129 data will be needed in the future for assessment of environmental impact in the region.</p