An effective palynological preparation procedure using hydrogen peroxide

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 (H 2 O 2 ) to extract palynomorphs by the physico-chemical disaggregation of the clay fraction. However, H 2 O 2 is a powerful oxidizing agent and hence can potentially destroy sedimentary organic material, including palynomorphs. A new method using hot H 2 O 2 , where exposure of the sample material to the H 2 O 2 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% H 2 O 2 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 H 2 O 2 . 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 H 2 O 2 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 H 2 O 2 method. These were all prepared using 30% H 2 O 2 . For comparison, they were also prepared quantitatively using HCl/HF and/or sodium hexametaphosphate [(NaPO 3 ) 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 H 2 O 2 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 H 2 O 2 and (NaPO 3 ) 6 . Both methods produced abundant miospores, however the H 2 O 2 procedure yielded far higher palynomorph concentrations than the (NaPO 3 ) 6 2 technique. Minor degradation of palynomorphs in the H 2 O 2 preparation was noted. The H 2 O 2 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 H 2 O 2 procedure....