This study covers the preliminary assessment of a novel accelerator mass spectrometry technique for rapid quantitation of polonium-210 in water samples.

A new method was developed to extract I-129 from urine samples and measure it using accelerator mass spectrometry (AMS). The samples were pre-treated in an autoclave with hydrogen peroxide and were then acidified with nitric acid, followed by the precipitation of iodine as silver iodide (AgI) for measurement by AMS. This new procedure is substantially faster than previous methods for the extraction of iodine from urine and results in less chemical waste. The efficiency and reproducibility of this method were evaluated by using I-125 as a yield tracer, eventually giving a recovery above 99%. To achieve this, several iterations of the method were required. The method was then successfully applied to measure I-129/ I-127 isotopic ratios and I-129 concentrations in 25 human urine samples. The AMS results for I-129 in urine ranged 3.3 x 10(6) atoms/L to 884 x 10(6) atoms/L and the isotope ratio (I-129/I-127) in human urine ranged from 7.38 x 10(-12) to 3.97 x 10(-10) with a median of 1.29 x 10(-15). This new method will be useful for investigations into the sources of iodine in the human diet and their relative importance for iodine sufficiency.

The existence of freshwater ferromanganese concretions has been known for decades, but we are not aware of a generally accepted explanation for their formation, and there has been little research into their potential use as records of Holocene climate and paleohydrology. A conceptual model is presented to describe the environmental and geochemical processes which result in the formation and growth of freshwater ferromanganese concretions. In order to evaluate their potential as historical geochemical records, a concretion from Magaguadavic Lake, New Brunswick, Canada is the focus of a detailed geochronological and geochemical investigation. The radiocarbon data provide a coherent growth curve and a maximum age for the concretion of 8448 ± 43 years, consistent with the establishment of Magaguadavic Lake as a stable post-glacial lacustrine system. The data suggest accretion rates of 1.5 and 3.4 mm per 1000 years during the Northgrippian and Meghalayan stages of the Holocene, respectively. The abrupt change in growth rate observed at the stage boundary may be an indicator of Holocene climate change. These features are consistent with inferences from previous research that warmer climate in the Northgrippian led to eutrophication in some lakes in eastern North America. The results confirm that freshwater Fe–Mn concretions may yield important information about past climatic and environmental conditions.

A new method was developed to extract 129I from urine samples and then measure it by AMS. The samples were pre-treated in an autoclave with hydrogen peroxide to remove unwanted compounds from the urine samples and were acidified with nitric acid, followed by precipitation of iodine as silver iodide (AgI) for measurement by AMS. This new procedure is substantially faster than previous methods for the extraction of iodine from urine and results in less chemical waste. The efficiency and reproducibility of this method were evaluated by using 125I as a yield tracer, eventually giving a recovery above 99%. To achieve this, several iterations of the method were required. The method was then successfully applied to measure 129I/127I isotopic ratios and 129I concentrations in 25 human urine samples. The AMS results for 129I in urine ranged 3.3 x 106 atoms/L to 884 x 106 atoms/L and the isotope ratio (129I/127I) in human urine ranged from 7.38 x 10-12 to 3.97 x 10-10 with a median of 1.29 x 10-10. This new method will be useful for investigations into the sources of iodine in the human diet and their relative importance for iodine sufficiency.

An analytical study was carried out on Eichrom resins (TRU, TEVA, UTEVA, and DGA) to identify a suitable solid phase extraction substrate to separate tin (Sn) from tellurium (Te). Standard metal solutions were spiked on batch tests in HCl and HNO3 media and the spiked analytes were determined by inductively coupled plasma mass spectrometry. The TRU resin exhibited the highest distribution coefficient (K-D) for Sn in 1.0mol L-1 HCl and the lowest K-D for Te. The TRU resin charged on Bio-Rad columns showed, respectively, 99.8 +/- 0.4% and 59.3 +/- 1.3% Sn and Te retention, and the hydrofluoric acid (0.50mol L-1) could wash down up to 92% of the loaded Sn, and the Te desorption can be kept as low as 5%.

High-resolution palaeolimnological analysis was implemented on a sediment core from Lough Muckno, a historically polluted inter-drumlin lake located in northeast Ireland. Focusing on chironomid and fossil pollen analyses, catchment conditions and human impacts on the lake environment during the last c. 200 years are identified and characterized. Chironomid community response to historical land-use change, reconstructed through a combination of pollen analysis and documentary evidence is evaluated in detail. The results provide insights into lake ecological conditions from a meso-eutrophic state in a nineteenth century agricultural setting to a highly eutrophic system in a landscape under modern pastoral management. Increasing livestock numbers and concomitant land fertilization are considered to be the main drivers affecting chironomid assemblages. Redundancy analysis indicates that grassland-based agriculture, inferred from Poaceae (grasses), the dominant component of palynological pastoral indicators, was the main variable controlling chironomid community composition. Lake resilience to nutrient abatement is reflected in a limited chironomid response to declining agricultural activity during the Great Irish Famine (c. 1846) and attempts at point and non-point pollution controls. Integrated interpretation of chironomid, pollen and non-pollen palynomorphs is shown to be a powerful tool for assessing the impacts of modern land-use change on lake ecology through time.

Dunnington DW, Spooner IS, Krkoek WH, Gagnon GA, Cornett RJ, Kurek J, White CE, Misiuk B, Tymstra D. 2018. Anthropogenic activity in the Halifax region, Nova Scotia, Canada, as recorded by bulk geochemistry of lake sediments. Lake Reserv Manage. 34:334-348.Separating the timing and effects of multiple watershed disturbances is critical to a comprehensive understanding of lakes, which is required to effectively manage lacustrine systems that may be experiencing adverse water quality changes. Advances in X-ray fluorescence (XRF) technology has led to the availability of high-resolution, high-quality bulk geochemical data for aquatic sediments, which in combination with carbon, nitrogen, C-13, and N-15 have the potential to identify watershed-scale disturbance in lake sediment cores. We integrated documented anthropogenic disturbances and changes in bulk geochemical parameters at 8 lakes within the Halifax Regional Municipality (HRM), Nova Scotia, Canada, 6 of which serve as drinking water sources. These data reflect more than 2 centuries of anthropogenic disturbance in the HRM that included deforestation, urbanization and related development, and water-level change. Deforestation activity was documented at Lake Major and Pockwock Lake by large increases in Ti, Zr, K, and Rb (50-300%), and moderate increases in C/N (>10%). Urbanization was resolved at Lake Fletcher, Lake Lemont, and First Lake by increases in Ti, Zr, K, and Rb (10-300%), decreases in C/N (>10%), and increases in N-15 (>2.0 parts per thousand). These data broadly agree with previous paleolimnological bioproxy data, in some cases identifying disturbances that were not previously identified. Collectively these data suggest that bulk geochemical parameters and lake sediment archives are a useful method for lake managers to identify causal mechanisms for possible water quality changes resulting from watershed-scale disturbance.

Technetium-99 (99Tc) determination at trace level by inductively coupled plasma mass spectrometry (ICP-MS) is challenging because there is no readily available appropriate Tc isotopic tracer. A new method using Re as a recovery tracer to determine 99Tc in fresh water samples, which does not require any evaporation step, was developed. Tc(VII) and Re(VII) were pre-concentrated on a small anion exchange resin (AER) cartridge from one litre of water sample. They were then efficiently eluted from the AER using a potassium permanganate (KMnO4) solution. After the reduction of KMnO4 in 2 M sulfuric acid solution, the sample was passed through a small TRU resin cartridge. Tc(VII) and Re(VII) retained on the TRU resin were eluted using near boiling water, which can be directly used for the ICP-MS measurement. The results for method optimisation, validation and application were reported.

The large inventory of radioactivity released during the March, 2011 Fukushima Dai-ichi nuclear reactor accident in Japan spread rapidly across the North Pacific Ocean and was first observed at the westernmost station on Line P, an oceanographic sampling line extending 1500 km westward of British Columbia (BC), Canada in June 2012. Here, time series measurements of 134Cs and 137Cs in seawater on Line P and on the CLIVAR-P16N 152°W line reveal the recent transport history of the Fukushima radioactivity tracer plume through the northeast Pacific Ocean. During 2013 and 2014 the Fukushima plume spread onto the Canadian continental shelf and by 2015 and early 2016 it reached 137Cs values of 6-8 Bq/m3 in surface water along Line P. Ocean circulation model simulations that are consistent with the time series measurements of Fukushima 137Cs indicate that the 2015-2016 results represent maximum tracer levels on Line P and that they will begin to decline in 2017-2018. The current elevated Fukushima 137Cs levels in seawater in the eastern North Pacific are equivalent to fallout background levels of 137Cs that prevailed during the 1970s and do not represent a radiological threat to human health or the environment.

TRU resin can be used to rapidly and selectively extract Tc(VII) and Re(VII). The retention capacity curves of Tc(VII) and Re(VII) for HNO3, HCl, H2SO4 and H3PO4 solutions were studied and prepared. Tc(VII) and Re(VII) were simultaneously extracted in 2 M H2SO4 and 1.5 M H3PO4 and were effectively separated from Mo(VI) and Ru(III). Tc(VII) and Re(VII) remained strongly bonded to the resin even after washing using a large volume of 2 M H2SO4 at a relatively high flow rate. Also, they were both completely eluted from the resin using 15 mL of near boiling water, an eluent directly compatible for ICP-MS instrument measurements.

The potential for atmospheric deposition of sulfur and nitrogen to affect lakes in the Northwestern USA to cause lake acidification was assessed by examining four lakes extending from southern Oregon into the central Washington Cascades. The four lakes were dilute (conductivity 2.2 to 3.6 μS/cm), low ANC (−3 to 11 μeq/L) systems, located in subalpine to alpine settings in designated wilderness areas. The four lakes were cored, dated with 210Pb and 14C, and analyzed for sediment nutrients and diatom remains. Diatom-inferred changes in chemistry were made possible through an earlier project to create a diatom calibration set for the Cascades. The three southern lakes exhibited volcanic inputs of ash or tephra, but diatom stratigraphy generally showed only modest responses to these events. None of the lakes exhibited any recent trends in diatom-inferred pH. The most significant finding with respect to paleolimnology was that Foehn Lake, WA, was formed in the twentieth century (1930 ± 7 years), likely as a result of melting of an adjacent snowfield. Current deposition was estimated using the AIRPACT-3 system, and lake chemistry was simulated using the CE-QUAL-W2 hydrodynamic model that had been modified to represent acid-base chemistry. The model simulations showed that the three southern lakes in the transect were insensitive to increases of nitrogen and sulfur until simulated increases reached 300% of current levels. Foehn Lake showed simulated declines of pH and ANC beginning at 50% increases over current deposition of S and N. The three southern lakes are resistant to changes from atmospheric deposition and other disturbances because of long hydraulic residence times, allowing internal processes to neutralize acidic inputs.

Small, temperate lakes are important to communities across Canada, but commonly lack the long-term water quality records that are required to assess the impact of development and environmental change. We measured a combination of bulk sediment geochemistry and stable isotopes of carbon and nitrogen in a 210Pb- and 14C-dated sediment core from Alta Lake, Whistler, British Columbia. Channel avulsion at AD 1754 ± 81 on the 21-Mile Creek alluvial fan resulted in increased deposition of organic matter with a signal of autochthonous production. A decrease in δ13C beginning at AD 1949 ± 17 indicates an increase in pelagic productivity relative to benthic productivity and/or sewage input to Alta Lake. A corresponding increase in δ15N indicates an increase in sewage-derived nutrients during the same time period. These changes were synchronous and coincide with the onset of rapid development in the Whistler Valley. Increased metal deposition (Cu, As, and Zn) during the same period resulted from watershed disturbance during highway construction. Cu, As, and Zn concentrations correlated positively with C concentrations and negatively with Ti and K, suggesting removal of metals from the water column is closely related to autochthonous organic matter deposition. Fe/Mn ratios and Mo concentrations were expected to respond to hypolimnetic oxygen availability in response to decreased flushing rate and increased productivity following the loss of inflow from 21-Mile Creek, but did not display a clear time-stratigraphic signal. Collectively, these data suggest that the combination of bulk geochemistry and stable isotopes was an effective suite of variables for inferring environmental change and the effects of development on Alta Lake.

The co-precipitation of actinides using NdF3 provides a robust and sensitive alternative method of preparing and analyzing actinide samples by accelerator mass spectrometry.

The Fukushima-Daiichi nuclear accident (FDNA) released iodine-129 (15.7 million year half-life) and other fission product radionuclides into the environment in the spring and summer of 2011. I-129 is recognized as a useful tracer for the short-lived radiohazard I-131, which has a mobile geochemical behavior with potential to contaminate water resources. To trace I-129 released by the FDNA reaching Canada, pre-accident and post-accident rain samples collected in Vancouver, on Saturna Island and from the National Atmospheric Deposition Program in Washington State were measured. Groundwater from the Abbotsford-Sumas Aquifer was sampled to determine the fate of I-129 that infiltrates below the root zone. Modeling of vadose zone transport was performed to constrain the travel time and retardation of I-129. The mean preaccident I-129 concentration in rain was 31 x 10(6) atoms/L (n = 4). Immediately following the FDNA, I-129 values increased to 211 x 10(6) atoms/L and quickly returned to near-background levels. However, pulses of elevated I-129 continued for several months. The increases in I-129 concentrations from both Vancouver and Saturna Island were synchronized, and occurred directly after the initial release from the FDNA. The I-129 in shallow (H-3/He-3 age < 1.4 years) Wassenaar et al. (2006) groundwater showed measurable variability through March 2013 with an average of 3.2 x 10(6) atoms/L (n = 32) that was coincident with modeled travel times for Fukushima I-129. The groundwater response and the modeling results suggest that I-129 was partially attenuated in soil, which is consistent with its geochemical behavior; however, we conclude that the measured variability may be due to Fukushima I-129 entering groundwater.

Iodine-129 ((129)I) is a biophilic, naturally occurring radioisotope (half-life: 1.57 × 10(7) years) that has been released in large quantities by nuclear fuel reprocessing. This iodine has cycled throughout the globe and chiefly the northern hemisphere and can be found in a wide variety of environmental materials, particularly organic rich soil and organic matter. Extracting iodine reliably from solid samples has been done by a variety of methods, however, pyrohydrolysis has been the most widely used. There is a wide variation between existing pyrohydrolysis techniques and this raises questions about the quantitative recovery of iodine from method to method. In order to quantify iodine recovery from pyrohydrolysis we have spiked samples with an iodine-125 radiotracer prior to combustion and trapping in an alkaline solution. Inorganic (125)I tracer was used as well as humic acid labeled with (125)I to simulate the behavior of (129)I and (127)I in complex organic substances and extract iodine regardless of how it is partitioned. Using these tracers we explored the effect on recovery of (125)I under a variety of combustion parameters. These include carrier gas flow rate and iodine volatilization temperature. We observed that the best recoveries of (125)I were at flow rates between 400 and 800 mL/min and most (125)I recoveries were above 85%. The experiment to determine the temperature at which iodine volatilizes from the sample showed two distinct trends for the release of iodine. One trend showed that most iodine is released at approximately 525 °C, while the other trend showed that the samples needed to reach 800 °C and remain there for at least an hour. These findings illustrate the usefulness and importance of using a quantitative recovery tracer for every iodine extraction. We then combusted and precipitated several Atlantic Ocean seaweed and standard reference materials for AMS analysis as AgI. The (129)I concentration of the seaweed ranged between 4.4-5.5 × 10(9) atoms/g and the (129)I/(127)I ratio was 2.3-2.9 × 10(-9), both of which compare well to published values for Atlantic seaweed. The results for the standard reference materials also agree with specified values indicating that this technique is reliable. By optimizing pyrohydrolysis conditions and testing the recovery of iodine with a (125)I tracer it is possible to quantify and maximize recovery from organic samples. This will allow for the investigation of variations in the (129)I concentration and (129)I/(127)I ratio with a high degree of precision in complex, organic rich samples.

A simple method was developed to separate Pu and Am using single column extraction chromatography employing N,N,N',N'-tetra-n-octyldiglycolamide (DGA) resin. Isotope dilution measurements of Am and Pu were performed using accelerator mass spectrometry (AMS) and alpha spectrometry. For maximum adsorption Pu was stabilized in the tetra valent oxidation state in 8 M HNO3 with 0.05 M NaNO2 before loading the sample onto the resin. Am(III) was adsorbed also onto the resin from concentrated HNO3, and desorbed with 0.1 M HCl while keeping the Pu adsorbed. The on-column reduction of Pu(IV) to Pu(III) with 0.02 M TiCl3 facilitated the complete desorption of Pu. Interferences (e.g. Ca2+, Fe3+) were washed off from the resin bed with excess HNO3. Using NdF3, micro-precipitates of the separated isotopes were prepared for analysis by both AMS and alpha spectrometry. The recovery was 97.7 +/- 5.3% and 95.5 +/- 4.6% for Am-241 and Pu-242 respectively in reagents without a matrix. The recoveries of the same isotopes were 99.1 +/- 6.0 and 96.8 +/- 5.3% respectively in garden soil. The robustness of the method was validated using certified reference materials (IAEA 384 and IAEA 385). The measurements agree with the certified values over a range of about 1-100 Bq kg(-1). The single column separation of Pu and Am saves reagents, separation time, and cost. (c) 2014 Elsevier B. V. All rights reserved.

RATIONALE An experimental Isobar Separator for Accelerator Mass Spectrometry (ISAMS) instrument has been used to demonstrate an on-line separation of HfF5(-) from its isobar WF5(-). This is necessary, in addition to sample preparation chemistry, for measuring (182)Hf at natural levels by Accelerator Mass Spectrometry (AMS). METHODS The device utilizes a radiofrequency quadrupole (RFQ) controlled gas cell, wherein anion-gas reactions at eV energies attenuate the interfering isobars of the analyte molecular anions, leaving HfF5(-) for AMS analysis. The RFQ also helps to control the multiple scattering resulting from the ion-gas collisions. RESULTS O2 gas was used in the HfF5(-)/WF5(-) separation and WF5(-) was attenuated by nearly 3 orders of magnitude while maintaining ~75% transmission of HfF5(-). It is expected that the transmission and attenuation can be increased by further research. CONCLUSIONS This result advances the possibility of detecting natural (182)Hf when AMS is supplemented with an isobar separator in the injection system.

Risks of noncancer causes of death, particularly cardiovascular disease, associated with exposures to high-dose ionizing radiation, are well known. Recent studies have reported excess risk in workers who are occupationally exposed to low doses at a low dose rate, but the risks of moderately fractionated exposures, such as occur during diagnostic radiation procedures, remain unclear. The Canadian Fluoroscopy Cohort Study includes 63,707 tuberculosis patients exposed to multiple fluoroscopic procedures in 1930-1952 and followed-up for death from noncancer causes in 1950-1987. We used a Poisson regression to estimate excess relative risk (ERR) per Gy of cumulative radiation dose to the lung (mean dose = 0.79 Gy; range, 0-11.60). The risk of death from noncancer causes was significantly lower in these subjects compared with the Canadian general population (P < 0.001). We estimated small, nonsignificant increases in the risk of death from noncancer causes with dose. We estimated an ERR/Gy of 0.176 (95% confidence interval: 0.011, 0.393) (n = 5,818 deaths) for ischemic heart disease (IHD) after adjustment for dose fractionation. A significant (P = 0.022) inverse dose fractionation effect in dose trends of IHD was observed, with the highest estimate of ERR/Gy for those with the fewest fluoroscopic procedures per year. Radiation-related risks of IHD decreased significantly with increasing time since first exposure and age at first exposure (both P < 0.05). This is the largest study of patients exposed to moderately fractionated low-to-moderate doses of radiation, and it provides additional evidence of increased radiation-associated risks of death from IHD, in particular, significantly increased radiation risks from doses similar to those from diagnostic radiation procedures. The novel finding of a significant inverse dose-fractionation association in IHD mortality requires further investigation.