AN EFFECTIVE PALYNOLOGICAL PREPARATION PROCEDURE USING
HYDROGEN PEROXIDE
JAMES B. RIDING1
JANE E. KYFFIN-HUGHES
BERNARD OWENS
British Geological Survey
Kingsley Dunham Centre
Keyworth
Nottingham NG12 5GG
United Kingdom
1corresponding author, e-mail:
jbri@bgs.ac.uk
Abstract
Most pre-Quaternary palynology samples are currently prepared by demineralisation
of the sediment/sedimentary rock matrix using hydrochloric and hydrofluoric acids
(HCl and HF respectively). If a consistently effective alternative to this procedure can
be developed, palynological processing will be made significantly less hazardous to
both laboratory personnel, and to the wider environment. Furthermore, most non-acid
processing methods are normally quicker and cheaper than matrix dissolution using
acid. Some authors have previously used hydrogen peroxide (H2O2) to extract
palynomorphs by the physico-chemical disaggregation of the clay fraction. However,
H2O2 is a powerful oxidizing agent and hence can potentially destroy sedimentary
organic material, including palynomorphs. A new method using hot H2O2, where
exposure of the sample material to the H2O2 is minimised, has been developed.
Crushed sample material in a suitable vessel is placed on a hot plate for one minute,
treated with 15-30% H2O2 for 10 minutes, then the residue is diluted with cold
distilled water. Disaggregated sample material tends to float, and is decanted into a
large vessel containing distilled water to further dilute the H2O2. If any
undisaggregated sample remains, the procedure is repeated several times if necessary.
Relatively indurated sedimentary lithotypes normally require several treatments. The
reason for this stepwise treatment is that the organic material is not exposed to H2O2
for sustained periods, thereby reducing the possibility of palynomorph
damage/degradation due to oxidation. When the sample matrix has been fully
disaggregated, the residue can be further processed as appropriate.
In this study, eight samples of Carboniferous, Jurassic, Paleogene, and
Quaternary age were prepared quantitatively using the new H2O2 method. These were
all prepared using 30% H2O2. For comparison, they were also prepared quantitatively
using HCl/HF and/or sodium hexametaphosphate [(NaPO3)6]. Quantitative
preparations allow the concentration of palynomorphs extracted to be determined, and
therefore the effectiveness of the techniques used can be compared objectively. The
palynomorph residues derived from these three techniques varied markedly. The H2O2
method does not consistently disaggregate all the sample material, particularly the
older and more indurated lithotypes. Some evidence of oxidation effects was
observed. Two samples of Mississippian mudstone from the U.S.A. were prepared
using H2O2 and (NaPO3)6. Both methods produced abundant miospores, however the
H2O2 procedure yielded far higher palynomorph concentrations than the (NaPO3)6
2
technique. Minor degradation of palynomorphs in the H2O2 preparation was noted.
The H2O2 and HCl/HF methods were compared directly on a palynomorph-rich
sample of Upper Carboniferous mudstone from offshore Scotland. Both preparations
produced abundant miospores. The HCl/HF method had significantly higher recovery
levels than the H2O2 procedure. It appears that the H2O2 method simultaneously
macerates the matrix, and oxidizes any amorphous organic material (AOM) present.
In this sample, the HCl/HF residue was relatively rich in AOM. By contrast, the H2O2
preparation is virtually clear of this phytoclast type, which partially obscures
palynomorphs. Two samples of the Middle Jurassic Grantham Formation of eastern
England were processed using H2O2 and HCl/HF. The two methods produced
abundant palynofloras of similar palynomorph concentrations. Two dinoflagellate
cyst acmes within the Danian (Paleogene) part of the Lopez de Bertodano Formation
of Seymour Island, Antarctica were also tested using H2O2, (NaPO3)6, and HCl/HF.
The H2O2 preparation completely destroyed the dominant taxon, Palaeoperidinium
pyrophorum, in one sample. By contrast, the (NaPO3)6 and HCl/HF preparations
produced abundant, fully representative palynofloras. In the other sample, the acme of
Spinidinium spp. is completely unaffected by the H2O2 preparation procedure. The
final sample of this study is an unconsolidated clay of Late Pleistocene age from
offshore Scotland. Both the H2O2 and HCl/HF preparations proved similar in both
taxonomic content and overall palynomorph yield.
The new method of preparation using hot H2O2 has proved to be extremely
effective. In particular, it appears to be superior to the (NaPO3)6 procedure for
indurated lithotypes. However care should be taken because H2O2 can destroy certain
dinoflagellate cysts and kerogen macerals which are especially susceptible to
oxidation. Further development work, and more comparative testing of the H2O2,
(NaPO3)6, and HCl/HF procedures, should be undertaken.