Pipette and Sieve Grain Size Analysis:
Detailed Instructions (2004) for a 20 Sample Run
[Procedure based upon Coventry and Fett (1979)]
Many days before analysis
(preferably right after sediment collection)
1) Place your sediment samples in foam or aluminum bowls to dry. In order to avoid mixing
specimens, label each bowl with the sample number you used when collecting them in the field.
Place enough sediment in the bowls to produce 20 to 30 grams of
material. Remove any
obvious plant/wood fragments before starting to dry your samples, but try to avoid removing
sediment with the detritus. If your sediment is very organic rich (e.g., > 15% organic), consider
oxidizing the sediment samples before doing grain size. (See item 2 below).
[20 minute prep
time required for this stage]
All sediment samples must be dry before you do your analyses. It would be best if you started
drying them right after you get back from the field. A low temperature drying oven (i.e., < 50 ºC)
may also be used to speed up the drying process, but use it expeditiously. Baked clay is almost
impossible to disaggregate.
2) If your sediment contains a lot of fine organic material (stuff that can’t be easily removed), you
might want to soak it in 30% hydrogen peroxide solution before doing grain size analysis. This
will oxidize the organics. As a general rule, oxidization should only be done if the sediment is
dominantly silt and clay and black in colour. Estuarine mud (e.g., Weeks Bay, Mobile Bay)
contains less than 6% organic material and does not have to be oxidized before grain size
analysis. If you elect to soak your sediment in H
solution, allow 2 days for oxidation to finish.
Carefully decant the excess solution before allowing the samples to air dry. H
burn exposed skin. Wear proper safety gear when using it (protective glasses, lab coats)
Three days before analysis
(after samples have completely dried)
1) Move the bowls containing your samples to the bench containing the analytical balance. From
the storage cabinet, obtain a box of plastic shaker bottles. There should be 5 boxes, each
containing 20 shaker bottles in the cabinet. Should you select the box identified Run 1, the shaker
bottles are labeled A-1, B-1, C-1, D-1… T-1. In the Run 2 box, the 20 shaker bottles are labeled
A-2, B-2,C-2, D-2… T-2 etc. Arrange the 20 bottles from the specific run that you are doing in a
row beside the balance
. Carefully and separately weigh out some sample from each of the bowls.
For sand-rich samples, extract 10-15 g, but for clay-rich samples, extract no more than 10 g.
Transfer the weighed sediment into one of the labeled shaker bottles and record its weight in the