Lower variability of radionuclide activities in upland dairy products compared to soils and vegetation: Implication for environmental survey

Abstract

Contamination of the environment by radionuclides is usually estimated using soil and grass sampling. However, radionuclides are often not homogeneously distributed in soils. In the alpine Mercantour region (Western Alps, France) a large heterogeneity in Chernobyl 137 Cs deposition has been previously observed. Sr contents are less variable in milk samples than in grass or soil samples. This can be attributed to the homogenization effect of cow vagrancy during grazing. Hence milk seems to be a more robust sample than soil or grass to evaluate the extent of contamination on a regional scale. We explore this idea by comparing own unpublished 90 Sr results and 90 Sr results from the literature to establish the relationship between altitude of grazing and contamination of soil and milk for Western Europe. There is a significant positive correlation between soil contamination and altitude and an even closer correlation between milk 90 Sr activity (A) and altitude (h): A = A 0 + e kAEh where A 0 is the expected activity of milk sampled at sea level (A 0 = 0.064 ± 0.014 Bq g À1Ca) and h is the altitude of grazing, k being a constant (k = 0.95 · 10 À3 ± 0.11 · 10 À3 m À1 Bq g À1 Ca). The fact that there is less scattering in the relationship for the 90 Sr milk -altitude than for 90 Sr soil -altitude suggests, again, that milk is a well-suited sample for environmental survey. The relationship between the altitude of grazing and the 90 Sr content of milk and cheese can also be used to assess the authenticity of dairy products.

Determining 241Pu in environmental samples: case studies in alpine soils

“…5). This result corresponds to previous studies that have concluded that Pu in both regions was originated by the NWT [22,23,27,42].…”

“…In the region, the mean annual precipitation varies between 1000 to 1500 mm, with about one third in the form of snow [26]. The soils have been well-characterized in terms of their chemical and physical properties [22,27]. A typical feature of these soils is their high content of organic matter, which amounts to up to 78% of the total weight at some depths.…”

“…This tendency may be explained by the increased levels of radioactive fallout at high altitude due to a higher precipitation rate [27].…”

“…Two alpine regions of Switzerland and France were selected for this study based mainly on two facts: firstly, the regions were relatively highly affected by the radioactive fallout in comparison with other low altitude regions; and secondly, they have been intensively investigated for other fallout radioisotopes [22,23,[26][27][28].…”

Aerosol deposition and origin in French mountains estimated with soil inventories of 210Pb and artificial radionuclides

“…Pollutants including N and S oxides, metals and artificial radionuclides are known to be concentrated in mountain soils (Branford et al, 1998;Huh and Su, 2004;Pourcelot et al, 2003Pourcelot et al, , 2007Weathers et al, 2000). In addition, high-elevation ecosystems are also highly sensitive to human impact because doi:10.1016/j.atmosenv.2007.10.083 environmental conditions are extreme and growing seasons are short.…”