The deepest sample from trench (78421) is a mature regolith containing a high abundance of agglutinates (68%%).
The highest 239+240Pu soil activity was 829 Bq/kg in a shallow sample (0 1 cm depth) near the trench sampling point.
By controlling the applied normal force (F n) between a probe and a sample surface, trenches or grooves with depths from a few to tens of a nanometer and widths from tens to hundreds of nanometers can be fabricated on both soft and hard substrates, involving polymer [13], silicon [14], oxides [15], magnetic metals, and semiconductor materials [16].
Fig. 2 Block samples from the KYD trench and sample positions of the radiocarbon dating.
The time-consuming excavation of entire root systems tends to limit measurements to only a few trees, but the trench sampling used to obtain the PN dataset provides a lower accuracy in terms of spatial characterisation of roots but enables the analysis of variability among more trees.
Then, the HGS cores were used instead of the trench samples.
Radiocarbon dating and measurements of 137Cs and excess 210Pb in the KYD trench samples and HGS cores were conducted to determine and constrain the ages of tsunami deposits at the Koyadori site along the Sanriku Coast in Northeast Japan.
The lack of any response of water levels in the trench-sampler to pumping reflects the large volume of available water when the water-level is in the zone accessible by the trench sampler.
The installation of a water-level logger in the trench sampler has enabled the collection of a data set for the water level in the trench and its response to rainfall.
For groundwater samples, 10 L of water was collected for radiochemical analysis, while for trench water samples, 500 mL was sufficient.
These reported average levels, and the eventual cleanup levels, are above the maximum measured 239+240Pu level at the LFBG of 829 Bq/kg in 0 1 cm surface soil (Table S1) and considerably exceed the median value on the LFBG trenched area within 10 m of the trench-sampler (31.7 Bq/kg).
