Sediment samples for palynology can be taken from cores in a tiny fraction of the time it takes to process and count the pollen. Because of that fact, about a dozen years ago I decided it would not prolong things too much if I made some extra measurements that would allow me to express the microfossil abundance either by volume or wet weight or dry weight, and at the same time record the water content of the sediment. If the samples were spiked with exotic pollen marker grains, pollen abundance could be expressed in units of grains/cm3, grains/g[wet] or grains/g[dry] as well as the traditional pollen percentage. And if the age of the sediment were known, one could also express the abundance in grains/cm2/yr (Maher, 1981).
I worked out a procedure for packing sediment into a calibrated stainless- steel measuring spoon, leveling the sediment with a knife edge, weighing it, and splitting the sample into two portions--one of which was wrapped in aluminum foil and dried in an oven; the other was processed for its pollen. All the sediment quantities were based upon weighing the empty spoon and foil, and accounting for the volume of the pollen and oven sub-samples by their weight fraction of the total wet weight of the spoon's sediment. (This procedure works best when the sediment is fine-grained and water-saturated.) I shudder when recalling the effort it took to take 134 samples from the core segments. Each sample required six steps of taring and weighing which were done with an older model torsion balance that was difficult to use. If run by an experienced and stubborn individual, it was capable of an accuracy of + 0.002 g. As the core was being sampled, each reading was double-checked and recorded on a paper tablet. A blank was left for the oven-dried portion which was weighed the following day. The raw data were then manually entered into a programmable calculator for further processing. I had a lot of data, but it was not handled very efficiently.
When I recently had occasion to take similar samples from a new series of cores, I decided it was time to purchase an electronic balance with a large digital display. In studying catalogs, I found that many of these instruments come with bi-directional RS-232-C interfaces--meaning they can be controlled from a computer. I decided a good choice for me was a Denver Instrument XE Series Model 100A sold by Fisher Scientific; it offered precision (± 0.0002 g) and simple operation at a very competitive price. Even though it had a large digital display, it seemed like a good idea to write a computer program so that the data could be acquired without ever having to copy any numbers by hand. The Model 100A's RS-232 port is like a socket on a US telephone which has four leads. Our electronics staff made a jack and cable to connect to the COM1 port on my IBM-compatible laptop computer.
SPOON-EZ.BAS is a QuickBasic program. It establishes a communication link with the balance at 2400 baud, one of the standard BASIC rates that also works with the Model 100A. The program functions well with the QBasic interpreter that comes with DOS 5.0. I suspect that the inner workings of many of today's electronic balances utilize very similar computer chips and that their commands are much alike. When the communication link is established between computer and balance, the usual "hand-shake" does not take place. The statement: OPEN "COM1:2400, N, 8, 2, RS, DS0" FOR RANDOM AS #7 LEN = 256 uses the RS and DS0 switches to tell the computer it should not "time out" when it receives no acknowlegement that the connection was opened. Let me explain the program by showing some sample data, and then I will explain how you can get a free copy and adapt it to your own needs and equipment.
It is assumed that the core will be unwrapped and ready for taking samples-- say from top to bottom--and that a sample's depth will serve as its label. You have a calibrated spoon and a supply of aluminum foil squares about 5 cm on a side that you have cut from a roll of foil. The foil will hold the sub- sample to be dried in the oven; its sample number can be engraved on a corner with a ballpoint pen. The spoon will be cleaned and dried after each use. I give it a moment in a ultrasonic bath with a little detergent, and then dip it in a small beaker of alcohol. When the spoon is then touched to a flame, the alcohol burns off quickly, leaving the spoon clean and dry for the next sample.
Generally the core sampling will take some time and may extend to a second day. One should therefore be able to stop and save data to a file, which can be recovered and continued at a later time. The initial weight file (with extension *.IWT for Initial WeighT) will have seven categories (1. Serial Number, 2. Empty Spoon Weight, 3. Spoon + Sediment Weight, 4. Empty Foil Weight, 5. Foil w/Sediment for Oven Weight, 6. Spoon w/Pollen Sample Weight, and 7. Foil w/Sed FROM Oven). The seventh category will be unknown (stored as a zero) until the oven-dried sample is weighed at a later session. When the program is run, it asks questions ("Does a *.IWT file exist for this core?", "Do you wish to do another sample? (Y/N)", etc.), and issues instructions ("Touch the Space Key to Tare the Empty Balance", "Touch the Space Key to weigh the clean empty spoon", "Touch the Space Key to weigh the filled spoon with its leveled sediment", etc.). Each time a weight is needed, the program actually instructs the balance to send 10 separate measurements, and the mean value is the one recorded. The balance is designed to provide a reading only when it meets its own standard for stability. The computer beeps whenever it is ready for a new measurement.
When the oven-dried samples are ready, one should be able to load the stored *.IWT file to complete the last column. The program will call for the aluminum-wrapped samples by sample number, and the dried sample's weight will also be the mean of 10 readings. This part of the process does not take long so there is no provision for saving the file in mid task. When all the samples in the file are complete, a Final WeighT file (*.FWT) is saved; it will contain all the information needed to characterize the pollen samples' water contents, weights, and volumes.
Spoon-EZ.BAS by L. J. Maher, Version 1.8
PROGRAM TO AUTOMATE WEIGHING SPOON SAMPLES FOR
POLLEN CONCENTRATION
----------------------------------------------
1. RECORD RAW WEIGHTS OF SAMPLES FROM CORE
TO AN INITIAL DISK FILE
[You can save the Initial WeighT (*.IWT)
file, stop, and continue it later.]
2. WEIGH DRIED SAMPLES FROM OVEN TO FINISH
INITIAL DISK FILE
[Weigh ALL the Dried Samples in the (*.IWT)
File in ONE operation. The results will
be saved as a Final WeighT (*.FWT) File]
(Steps 1 and 2 MUST BE COMPLETED BEFORE steps 3 and 4.)
3. PRODUCE COMPREHENSIVE DISK FILE OF POLLEN
SAMPLE VOLUMES AND WEIGHTS
4. PRODUCE MINI DISK FILE OF JUST SAMPLE
VOLUMES AND WEIGHTS
E. End Program
Press 1,2,3,4 or E to continue _
Fig. 1. Main menu of SPOON-EZ.BAS
I thought it would help to include some simple test files here to show the results. For the test, I have used my actual measuring spoon and five separate pieces of aluminum foil. The stainless spoon was sold as a 1/4 teaspoon measure. A dictionary conversion chart suggests that a level 1/4 teaspoon should equal 1.232 ml. I calibrated my spoon by weighing 100 leveled spoons of modeling clay of known specific gravity. The weight variation among the samples was equivalent to a mean spoon volume of 1.169 ml with a standard deviation of 0.014 ml. The calibrated mean volume of my spoon is therefore about 5 per cent less than the value stamped on its surface.
In a normal run, no effort is made to keep the size of the oven sub-samples and the pollen sub-samples exactly constant; it is only important to know what they weighed. In this example, however, I will substitute gram balance weights for the sediment so that we can predict what the answers will be and then check them against the calculated results. I used a 3-gram and a 2-gram weight--5 g in all--to represent the weight of a level spoonful of sediment. The 3 g weight would be the pollen sample; the 2 g weight represented the por- tion of wet sediment that was going to be sent to the oven. The oven sample was placed on its foil and weighed. The pollen sample represents 3/5 of the mass (and therefore the volume) of the spoon which suggests--if the 5 g had actually been sediment that filled the spoon--that the pollen sample's volume will be 0.701 ml with s.d. 0.008 ml.
The five test samples were given arbitrary labels. They were saved as INQUATST.IWT, which has the structure of a "Wisconsin RAW" file. It is duplicated below:
Test of Known Weights 7 5 10 5.06846 10.068 .149 2.1491 8.0682 0 20 5.06849 10.06837 .09799 2.09827 8.06839 0 30 5.0678 10.06797 .1028 2.10316 8.068151 0 40 5.068379 10.06771 7.895999E-02 2.07877 8.068399 0 50 5.068389 10.0681 .15851 2.15823 8.06797 0 Serial Nbr Empty Spoon Wt Spoon + Sediment Wt Empty Foil Wt Foil w/Sed for Oven Wt Spoon w/Pollen Sample Wt Foil w/Sed FROM Oven This file made with Spoon-EZ.BAS, Version 1.8 on 06-28-1993 at 14:26:29.The first line is a title, the second line is the number of categories (7), and the third line is the number of samples (here 5). Data for the five samples then occur on succeeding lines, each with seven categories. The category names are added after the data, and a last line tells when the file was made. You will note that the last category--Foil w/Sed FROM Oven--is always zero in the *.IWT file. No effort is made to format the weight data; they are simply the mean value of the 10 readings. Generally, the only time a *.IWT file is ever looked at is when catastrophe strikes during a session-- such as dropping a sample on the floor. In that case, one can simply finish the sample's weighing sequence by recording the weight of an empty balance. When the program asks for the next sample number, enter the same number and re-sample the core at the same level. After the file has been saved, read it with as ASCII text editor, delete the bad line, and reduce the recorded number of samples (3d line) by one.
Item 2 from the SPOON-EZ menu was then selected and INQUATST.IWT was loaded from disk. In this trial the oven-dry sample used the same foil as the original "wet" sample, but with a 1 g weight substituted. This simulates a sediment that has lost half its mass on drying; its (dry weight/wet weight) ratio is thus 0.5. When the five oven-dry samples were completed, the final weight file was saved as INQUATST.FWT which is reproduced below:
Test of Known Weights 7 5 10 5.06846 10.068 .149 2.1491 8.0682 1.149 20 5.06849 10.06837 .09799 2.09827 8.06839 1.09854 30 5.0678 10.06797 .1028 2.10316 8.068151 1.10297 40 5.068379 10.06771 .0789 2.07877 8.068399 1.07881 50 5.068389 10.0681 .15851 2.15823 8.06797 1.15909 Serial Nbr Empty Spoon Wt Spoon + Sediment Wt Empty Foil Wt Foil w/Sed for Oven Wt Spoon w/Pollen Sample Wt Foil w/Sed FROM Oven This file made with Spoon-EZ.BAS, Version 1.8 on 06-28-1993 at 14:31:42.The Final Weight (*.FWT) file provides all the information needed to characterize the volume and weight of the pollen samples as well as their water content. Once you have made a *.FWT file, you can delete the Initial Weight (*.IWT) file.
Now if you choose item 3 on the SPOON-EZ menu, you can produce a Volume-WeighT (*.VWT) file which displays all the data you would need to document your work.
Part of INQUATST.VWT--showing sample 10 only to conserve space--is reproduced below:
Test of Known Weights
Number of samples = 5
This file made with Spoon-EZ.BAS, Version 1.8 on 06-28-1993 at 14:51:21.
All weights based on mean of 10 balance readings.
**SAMPLE NUMBER 10
Spoon Vol Mean = 1.169 ml S.D.= 0.014 ml
Spoon Weight = 5.06846 g
Spoon Plus Sediment Weight = 10.06800 g
Empty Foil Weight = 0.14900 g
Foil Plus Sediment For Oven = 2.14910 g
Foil + Sediment FROM OVEN = 1.14900 g
Total WET Sed Wt in Spoon = 4.99954 g
Wt of Wet Sediment For Oven = 2.00010 g
Wt of Dry Sediment FROM Oven = 1.00000 g
Ratio of Sediment's Dry Wt to Wet Wt = 0.49997
Ratio Pollen Sed Wet Wt/Total Sed Wet Wt = 0.60000
Pollen Sample WET Wt = 2.9997 g
Pollen Sample DRY Wt = 1.4998 g
POLLEN SAMPLE VOLUME = 0.7014 ml S.D.= 0.008 ml
**SAMPLE NUMBER 10
...
It is good practice to load an *.VWT file into your word-processor and run off
a paper copy for your files. Finally, if you choose menu item 4, you can
produce a SUMmary (*.SUM) file. And if you never want to copy any of these
numbers by hand, you can load a *.SUM file, read the first 8 lines as dummy
variables, and have each sample's values available to be read by machine for
further processing. INQUATST.SUM is reproduced below:
Test of Known Weights Number of samples = 5 This file made with Spoon-EZ.BAS, Version 1.8 on 06-28-1993 at 14:51:33. All weights based on mean of 10 balance readings. Sample Volume StdDev. Wet Wt Dry Wt Dry Wt/Wet Wt Nbr ml ml g g Ratio 10.0 0.701 0.008 2.9997 1.4998 0.49997 20.0 0.701 0.008 2.9999 1.5006 0.50020 30.0 0.701 0.008 3.0004 1.5002 0.49999 40.0 0.701 0.008 3.0000 1.4999 0.49997 50.0 0.701 0.008 2.9996 1.5009 0.50036By examining these test data, it can be seen that the expected pollen sample volumes and standard deviations were recovered. The pollen sample wet and dry weights and the (dry weight/wet weight) ratios are accurate to about +/- 1 mg.
If this program would be useful to you, it is available by anonymous ftp in the subdirectory /pub/inqua at geology.wisc.edu. SPOON-EZ.EXE is a self- extracting file containing SPOON-EZ.BAS and a sample *.FWT file. Menu items 1 and 2 will not work unless your computer's COM1 port is connected to a compatible electronic balance; you can try menu items 3 and 4 reading the *.FWT file in your default directory.
Near the beginning of the BASIC source code, you will find a number of variables defined that can be changed to meet your own needs. These include the mean and s.d. of your measuring spoon, the name and model of your balance, the number of readings to average, and the commands to cause the balance to tare, calibrate and to send its weight reading. You can even change the name of the program; if you do, remember to rename the *.BAS file to conform to your choice.
Consult the instruction manual for your electronic balance to determine how to adjust its baud rate. Most have set-up programs that can be accessed with a terminal emulator like PROCOMM.
Measuring mud is [almost] fun again. Let me know if you have questions or problems.
Reference.
Maher, Louis J., Jr. 1981. Statistics for microfossil concentration measurements employing samples spiked with marker grains: Review of Palaeobotany and Palynology, 32: 153-191.