Partition coefficient of Ra in witherite

Cyanobacteria Accumulate Radium (226Ra) within Intracellular Amorphous Calcium Carbonate Inclusions

“…The Si wafer was ionized beforehand by glow discharge, that is, by exposing it to high-energy plasma for 30 s. Simultaneously, some cells were fixed with 2.5% glutaraldehyde and mounted on the pre-ionized Si wafer, air-dried, and coated (10 nm Au). Samples were analyzed on the CAMECA NanoSIMS 50L (University of Western Australia) using a radio-frequency (RF) O − ion source to detect 23 Na + , 28 Si + , 31 P + , 40 Ca + , 88 Sr + , 138 Ba + , and 226 Ra + ion species. Randomly selected cells occurring as low relief monolayers (as recorded by a charge-coupled device (CCD) equipped to NanoSIMS) were analyzed by rastering a ∼80 nm diameter (∼5 pA) beam on 8 μm square raster areas with settings D1 (aperture diaphragm) = 4, L1 (lens) = 6800 V selected to maximize instrument resolution and sensitivity.…”

“…Data analysis was done using the Look@ NanoSIMS Matlab GUI to align and accumulate planes and extract the pixel-by-pixel total ion counts. 32 Using the Gaussian finite mixture model fitted by the expectation−maximization (EM) algorithm (R-package mclust, 33 ), the pixels from two regions (8 × 8 μm 2 ) were categorized into different clusters according to the bivariate distribution of 40 Ca + and 31 P + counts. Each cluster was described using a bivariate Gaussian component.…”

“…Such a rapid removal of Ba in a biotic setup relative to noninoculated control suggests the involvement of S3). Figure 2 shows the secondary-ion distribution map of 23 Na + , 226 Ra + , 31 P + , 40 Ca + , 138 Ba + , and 88 Sr + collected from unfixed G. lithophora (Ra+) cells. The maximum total count per pixel detected for 226 Ra + , 40 Ca + , 31 P + , 138 Ba + , and 88 Sr + equals 14, 133,884, 2834, 73,139, and 21,083 respectively.…”

“…Figure 2 shows the secondary-ion distribution map of 23 Na + , 226 Ra + , 31 P + , 40 Ca + , 138 Ba + , and 88 Sr + collected from unfixed G. lithophora (Ra+) cells. The maximum total count per pixel detected for 226 Ra + , 40 Ca + , 31 P + , 138 Ba + , and 88 Sr + equals 14, 133,884, 2834, 73,139, and 21,083 respectively. Numerous cells without any inclusions (referred to as empty cells) were observed in unfixed G. lithophora samples (Figures 2 and S5).…”

“…Gaussian clustering of the bivariate distribution of 40 Ca + and 31 P + counts per pixel revealed a total of 20 clusters. Figure 3 shows the mean ion count per pixel within each Gaussian cluster.…”