A sensitive method to determine 210Po and 210Pb in environmental samples by alpha spectrometry using CuS micro-precipitation.

A new sensitive method to determine polonium-210 (210Po) and lead-210 (210Pb) in a diversity of environmental samples was developed. For fresh and marine waters, Po was pre-concentrated using a titanium (III) hydroxide (Ti(OH)3) co-precipitation. Solid environmental samples were digested with nitric acid (HNO3) and hydrogen peroxide (H2O2). The alpha thin layer source was prepared using CuS micro-precipitation and 210Po was measured by alpha spectrometry. Lead-210 was left to decay for up to a year and indirectly measured via its progeny, 210Po. The chemical recoveries for 210Po and 210Pb were high, 90% and 97%, respectively, for a large variety of samples and a very low minimum detectable activity (MDA) was obtained. The method was validated using standardized solutions and certified reference materials.

Sr-90 soil to plant transfer factor reduction using calcium and polymer soil amendments.

Introducing calcium into soils can inhibit Sr-90 uptake by plants. To test the efficacy of calcium amendments on the inhibition of Sr-90 uptake by edible plants, a number of different calcium applications, including calcium nitrate, calcium thiosulfate and a mixture of both liquid solutions, were used in this study. Pea plants (Pisum sativum 'Sabre') grown in Sr-90 contaminated soil from seeds to maturity were watered with these calcium solutions. Two different polymers, one inert and one nutrient enriched, were incorporated into the contaminated soil where pea seeds were sowed to ascertain a continuous supply of calcium and essential nutrients. Results show that the heterogeneity of Sr-90 distribution in soil translated to disparate Sr-90 contents in plant tissues. However, on average, irrigation with calcium solutions in conjunction with the usage of polymers consistently yielded a reduction in Sr-90 uptake by the plants. The lowest soil-to-plant transfer factor (TF) values were measured in the edible pea part of the plant, followed by the flowers, roots, stems, pea shells and then leaves. TF values for pea shells were between 4.9 and 20.9, and between 0.3 and 2.8 for the peas. Results do not allow the identification of one particular chemical solution that would systematically be the best choice to minimize Sr-90 uptake.

Permafrost thaw and implications for the fate and transport of tritium in the Canadian north.

Layers of permafrost developed during the 1950s and 1960s incorporated tritium from the atmosphere that originated from global nuclear weapons testing. In regions underlain by substantial permafrost, this tritium has been effectively trapped in ice since it was deposited and subject to radioactive decay alone, which has substantially lengthened its environmental half-life compared to areas with little or no permafrost where the weapons-test era precipitation has been subject to both decay and hydrodynamic dispersion. The Arctic is warming three times faster than other parts of the world, with northern regions incurring some of the most pronounced effects of climate change, resulting in permafrost degradation. A series of 23 waterbodies across the Canadian sub-Arctic spanning the continuous, discontinuous and isolated patches permafrost zones in northern Manitoba, Northwest Territories and Labrador were sampled. Surface water and groundwater seepage samples were collected from each lake and analyzed for tritium, stable isotopes (δ18O and δ2H) and general water chemistry characteristics. Measured tritium was significantly higher in surface waters (SW) and groundwater seepage (GW) in water bodies located in the sporadic discontinuous (64 ±â€¯15 T U. in SW and 52 ±â€¯9 T U. in GW) and extensive discontinuous (53 ±â€¯7 T U. in SW and 61 ±â€¯7 T U. in GW) permafrost regions of the Northwest Territories than in regions underlain by continuous permafrost in northern Manitoba (<12 T U. in both SW and GW) or those within isolated patches of permafrost in Labrador (16 ±â€¯2 T U. in SW and 21 ±â€¯4 T U. in GW). The greatest tritium enrichment (up to 128 T U.) was observed in lakes near Jean Marie River in the Mackenzie River valley, a region known to be experiencing extensive permafrost degradation. These results demonstrate significant permafrost degradation in the central Mackenzie River basin and show that tritium is becoming increasingly mobile in the sub-Arctic environment-at concentrations higher than expected-as a result of a warming climate. A better understanding of the cycling of tritium in the environment will improve our understanding of Arctic radioecology under changing environmental conditions.