binfordActivity: binfordActivity

In shiggo/jezioro: Tools for Paleolimnological Analyses at the Paleoecological Environmental Assessment and Research Laboratory

Description

binfordActivity uses the appropriate Region of Interest (ROI) values from the gamma counter to correct the 210Pb, 214Bi and 137Cs activities for the amount of sediment in the gamma tube as well as the background measurements of the gamma counter.

Usage

binfordActivity(d, LakeName = "Lake Name", live = 80000, PbBk = 0, BiBk = 0, 
CsBk = 0, PbBkErr = 0, BiBkErr = 0, CsBkErr = 0, graph.units="dpm")

Arguments

d	the matrix or data frame containing the input data.
LakeName	Name of the lake being analyzed. Defaults to "Lake Name".
live	Time in seconds that the samples were counted for. Defaults to 80000.
PbBk	Background 210Pb (cpm). Defaults to 0.
BiBk	Background 214Bi (cpm). Defaults to 0.
CsBk	Background 137Cs (cpm). Defaults to 0.
PbBkErr	Background Error for 210Pb (cpm). Defaults to 0.
BiBkErr	Background Error for 214Bi (cpm). Defaults to 0.
CsBkErr	Background Error for 137Cs (cpm). Defaults to 0.
graph.units	determines whether activities should be plotted as dpm/g ("dpm") or Bq/g ("bq"). Defaults to "dpm".

Details

binfordActivity calculates the activity of the 210Pb, 137Cs, and 214Bi isotopes, corrected for the efficiency of the gamma counter device, and the time between sediment core collection and analysis. A plot is generated of the corrected isotope activities vs. sediment core depth. The data to be examined should be in the form of a matrix or data frame with the following 14 columns:

• INTTOP: top of the analyzed interval (cm)

• INTBOT: bottom of the analyzed interval (cm)

• DATECORR: number of days between core collection and analysis of the interval

• ROI1: sum of the activity of the 5 channel region of interest immediately less than the 210Pb photopeak (ROI1 from the Maestro ROI Report)

• ROI2: sum of the activity of the 10 channel region of interest centered on the 210Pb photopeak (45.5keV; ROI2 from the Maestro ROI Report)

• ROI3: sum of the activity of the 5 channel region of interest immediately greater than the 210Pb photopeak (ROI3 from the Maestro ROI Report)

• ROI4: sum of the activity of the 5 channel region of interest immediately less than the 214Bi photopeak (ROI10 from the Maestro ROI Report)

• ROI5: sum of the activity of the 10 channel region of interest centered on the 214Bi photopeak (609keV; ROI11 from the Maestro ROI Report)

• ROI6: sum of the activity of the 5 channel region of interest immediately greater than the 214Bi photopeak (ROI12 from the Maestro ROI Report)

• ROI7: sum of the activity of the 5 channel region of interest immediately less than the 137Cs photopeak (ROI13 from the Maestro ROI Report)

• ROI8: sum of the activity of the 10 channel region of interest centered on the 137Cs photopeak (662keV; ROI14 from the Maestro ROI Report)

• ROI9: sum of the activity of the 5 channel region of interest immediately greater than the 137Cs photopeak (ROI15 from the Maestro ROI Report)

• WTinTube: mass (g) of dried sediment added to the gamma tube (equivalent to WT_GAMMA in binfordRho)

• HTinTube: height (mm) of the sediment added to the gamma tube, generally measured to 3 decimal places using an accurate set of calipers

NOTE: Columns 1 and 2 must have values for all samples prepared for gamma analysis (the same values entered into Columns 1 and 2 of binfordRho), but no values for columns 3-9 in cases where samples have not yet been run or are not required (in cases where background has been reached).

binfordActivity is intended to be run in an iterative function following analysis of each sample, thereby allowing accurate and timely determination of when supported levels of 210Pb have been reached, in order to avoid the superfluous analysis of samples beyond background.

It is very important to use the correct background and error measurements (e.g. PbBk, PbBkErr, etc.). That is, the values specific to both the gamma counter used and the time period when the samples were measured.

Value

binfordActivityOutput table of results for use with the binfordDates function.

Author(s)

Adam Jeziorski, Joshua Thienpont

References

Schelske CL, Peplow A, Brenner M, Spencer CN (1994) Low-background gamma counting: applications for 210Pb dating of sediments Journal of Paleolimnology 10: 115-128

Examples

#Imports the example activity data for a sediment core subsampled prior to freeze-drying
data(binfordActivityInput)
binfordActivity(binfordActivityInput)

shiggo/jezioro documentation built on Sept. 7, 2020, 7:34 p.m.