Transfer parameter values in temperate forest ecosystems: a review

Area of Science:

• Environmental Science
• Ecology
• Radiochemistry

Background:

• Forests are complex ecosystems with diverse species, strata, and soil layers, leading to variable radionuclide transfer and redistribution patterns.
• Soil serves as the primary long-term reservoir for radionuclides, posing a continuous risk of plant and food contamination.
• Aggregated transfer factor (T(ag)) is used to quantify radionuclide contamination in forest products, integrating environmental and biological factors.

Purpose of the Study:

• To review quantitative information on radionuclide transfers to various forest biota, including trees, understorey vegetation, mushrooms, berries, and game animals.
• To compare radionuclide transfer dynamics in forest ecosystems with those in agricultural lands.

Main Methods:

• Literature review of quantitative data on radionuclide transfers.
• Analysis of aggregated transfer factor (T(ag)) values for different forest components and species.
• Comparison of contamination levels and transfer rates across various forest ecosystems (temperate, boreal) and biota.

Main Results:

• Mean T(ag) values for radiocaesium and radiostrontium in trees are around 10(-3) m(2)kg(-1) (dry weight), with foliage being more contaminated than wood.
• Radionuclide transfer to mushrooms and berries is significantly higher than in agricultural settings, with T(ag) for mushrooms varying widely (10(-3) to 10(1) m(2)kg(-1)) and berries around 0.01-0.1 m(2)kg(-1) (dry weight).
• Transfer to game animals and reindeer depends on soil and pasture conditions; muscle activity concentrations show variable decline rates, with wild boar exhibiting no decline due to feeding habits. In boreal forests, late-phase T(ag) for (137)Cs in moose and birds is ~0.01 m(2)kg(-1) (fresh weight).

Conclusions:

• Forest ecosystems demonstrate unique and often higher radionuclide transfer pathways compared to agricultural lands, particularly for specific biota like mushrooms and berries.
• The soil compartment's role as a long-term reservoir necessitates continued monitoring of radionuclide contamination in forest products.
• Variability in transfer factors is influenced by ecosystem characteristics, species-specific traits, and environmental conditions, requiring location-specific assessments.