Fig. 4

Radial distribution of the ¹³⁷Cs/¹³³Cs ratio in wood sampled at different vertical positions in 2014. a–e Japanese cedar (Cryptomeria japonica); f, g Japanese cypress (Chamaecyparis obtusa); h, i Japanese larch (Larix kaempferi). ND letters indicate that ¹³⁷Cs activity in the samples was under the detection limit and show the detection limit values. SW sapwood, HW heartwood