Radioactivity levels in major French rivers: summary of monitoring chronicles acquired over the past thirty years and current status

Abstract

Since the beginning of the 1990 s, liquid releases of gamma-emitting radionuclides from French nuclear facilities have generally fallen by almost 85%. Almost 65% of gamma-emitting liquid effluents released into freshwater rivers concerned the River Rhône (Southeast France), with around 85% of this originating from the Marcoule spent fuel reprocessing plant. Upstream of French nuclear plants, artificial radionuclides still detected by gamma spectrometry in 2006, include (137)Cs, (131)I as well as (60)Co, (58)Co and (54)Mn in the case of the Rhine (Switzerland nuclear industries). In the wake of the fallout from the Chernobyl accident, (103)Ru, (106)Rh-Ru, (110 m)Ag, (141)Ce and (129)Te were detected in rivers in the east of France. Some of these radionuclides were found in aquatic plants until 1989. In eastern France, (137)Cs activity in river sediments and mosses is still today two to three times greater than that observed in similar environments in western France. No (134)Cs has been detected upstream of nuclear plants in French rivers since 2001. Downstream of nuclear plants, the gamma emitters still detected regularly in rivers in 2006 are (137)Cs, (134)Cs, (60)Co, (58)Co, (110 m)Ag, (54)Mn, (131)I, together with (241)Am downstream of the Marcoule spent fuel reprocessing plant. Alpha and beta emitters such as plutonium isotopes and (90)Sr first entered freshwaters at the early 1950s due to the leaching of soils contaminated by atmospheric fallout from nuclear testing. These elements were also introduced, in the case of the Rhône River, via effluent from the Marcoule reprocessing plant. Until the mid 1990 s, plutonium isotope levels observed in the lower reaches of the Rhône were 10 to 1000 times higher than those observed in other French freshwaters. Data gathered over a period of almost thirty years of radioecological studies reveal that the only radionuclides detected in fish muscles are (137)Cs, (90)Sr, plutonium isotopes and (241)Am. At the scale of the French territory, there is no significant difference since the mid 1990 s between (137)Cs activity observed downstream of nuclear facilities and that observed upstream, whether in sediments, mosses and fish. Finally, this study highlights that the natural radioactivity of surface freshwaters are around 25 times greater than artificial radioactivity from gamma emitters. However, non gamma emitters released by nuclear industries, such as (3)H, may lead to artificial activity levels 2 to 20 times higher than natural levels.

Historical levels of heavy metals and artificial radionuclides reconstructed from overbank sediment records in lower Rhône River (South-East France)

“…Martin and Thomas, 1990;Lambrechts et al, 1992;Santiago et al, 1994;Pont et al, 1996;Dange, 2002;Elbaz-Poulichet, 2005;Eyrolle et al, 2005Eyrolle et al, , 2008Rolland et al, 2005;Antonelli et al, 2008). However these works concerned short term surveys starting in the 1990's and the long term trend of these PCTE is unknown.…”

“…Similar activities (1.0 ± 0.2 to 27.1 ± 2.5 Bq kg À1 ) were measured in the Petit Rhô ne sediment deposits following the 2003 flood event (Eyrolle et al, 2006). Currently, 137 Cs activities of suspended particles transported along the lower reaches of the River tend to a minimum value of 15 ± 4 Bq kg À1 for rising water discharges Antonelli et al, 2008;Eyrolle et al, 2008). A subsurface peak, between 37 and 45 cm depth, followed by a progressive decrease of 137 Cs with depth is observed.…”

Caractéristiques radiologiques des canaux de transport d’eau – Exemple du réseau hydraulique régional Languedoc Roussillon

“…Elle est composée des différents éléments de filiation des chaînes de l' 238 Eyrolle et al, 2008). 1982 1984 1986 1988 1990 1992 1994 1996 1999 2001 2003 2005 2007 1982 1984 1986 1988 1990 1992 1994 1996 1999 1982 1984 1986 1988 1990 1992 1994 1996 1999 2001 2003 2005 2007 Les teneurs en tritium organiquement lié dans les sédi-ments du canal varient de 43,5 ± 2,2 Bq/L à 58,7 ± 3,0 Bq/L d'eau de combustion.…”

Origins and trend of radionuclides within the lower Rhône River over the last decades

“…As different decay products are never exhaustively quantified at the same time, the assessment of the natural radioactivity of water or sediment is based on the assumption that two elements measured in the same decay chain are at radioactive equilibrium. In this case, the natural radioactivity of water can be approximated by the following equation (1) (Eyrolle et al, 2008). For comparison, the natural radioactivity of sediments from the Têt, a coastal river in the department of Pyrénées Orientales, west of the Hérault, is between 2000 and 2500 Bq/kg.…”