Short- and long-term patterns of ¹³⁷Cs in fish and other aquatic organisms of small forest lakes in southern Finland since the Chernobyl accident.
We summarize the patterns of ¹³⁷Cs activity concentrations and transfer into fish and other biota in four small forest lakes in southern Finland during a twenty-year period following the Chernobyl accident in April 1986. The results from summer 1986 showed fastest accumulation of ¹³⁷Cs into planktivorous fishes, i.e. along the shortest food chains. Since 1987, the highest annual mean values of ¹³⁷Cs have been recorded in fish occupying the highest trophic levels, for perch (Perca fluviatilis) 13,600 Bq/kg (ww) and for pike (Esox lucius) 20,700 Bq/kg (ww). At the same time, activity concentrations of ¹³⁷Cs in crustacean zooplankton and Asellus aquaticus have ranged between 1000 and 19,500 Bq/kg (dw). In 2006, 5-28% of the 1987 ¹³⁷Cs activity concentration levels were still present in perch and pike. Since 1989 their ¹³⁷Cs activity concentrations in oligohumic seepage lakes have remained significantly higher than in polyhumic drainage lakes due to the increased transfer of ¹³⁷Cs into fish in the seepage lakes with lower electrolyte concentrations, longer water retention times and lower sedimentation rate.
Finnish Game and Fisheries Research Institute, Evo Game and Fisheries Research, FI-16970 Evo, Finland. martti.rask@rktl.fi
Martti
M
Rask
Ritva
R
Saxén
Jukka
J
Ruuhijärvi
Lauri
L
Arvola
Marko
M
Järvinen
Ulla
U
Koskelainen
Iisa
I
Outola
Pekka J
PJ
Vuorinen
D000704:Analysis of Variance; D000818:Animals; D002588:Cesium Radioisotopes / Q000032:analysis*; D047852:Chernobyl Nuclear Accident; D003445:Crustacea / Q000737:chemistry*; D004784:Environmental Monitoring / Q000706:statistics & numerical data*; D005387:Finland; D005399:Fishes / Q000378:metabolism*; D020387:Food Chain; D060106:Lakes; D014875:Water Pollutants, Radioactive / Q000032:analysis; D015048:Zooplankton / Q000737:chemistry*
D002588:Cesium Radioisotopes; D014875:Water Pollutants, Radioactive