A comparison of pollen extraction methods confirms dense‐media separation as a reliable method of pollen preparation

Abstract

10Palynology is a crucial proxy for understanding Quaternary environmental change. A 11 range of laboratory preparation techniques has been developed to deal with the 12 extraction of pollen in different sedimentary contexts. Here, we present a comparison 13 of the conventional hydrofluoric acid (HF) method and the dense-media separation 14 method using sodium polytungstate (SPT). We examine pollen, non-pollen 15 palynomorphs (NPPs) and microcharcoal by undertaking parallel preparation and 16 counting of thirty paired samples from three sites in the Middle Atlas Mountains, 17Morocco, with contrasting environmental and sedimentary conditions. Differences 18 between microfossil counts are assessed visually and statistically, using ANOVA and 19 linear regression. We observe that the typical offset between counts for the five most 20 common pollen and NPPs produced by the two methods (µ=1.6%, sd=0.9%) is 21 considerably smaller than the 95% uncertainty associated with the standard counting 22 procedure (µ=6.8%, sd=2.7%). There is no statistically significant difference 23 associated with the preparation methods, and no significant deviation from a linear 24 relationship between the results obtained by the two methods. There are advantages 25 and disadvantages to both methods in terms of preparation time and visual 26 characteristics. This study confirms that results for pollen, NPPs and microcharcoal 27 obtained by either preparation method can be directly compared. 28

A quantitative comparison of microfossil extraction methods from ice cores

“…Adding microfossil markers to palynological sediment samples has been a standard in palynology since the early 1970s (e.g. Stockmarr, 1971; Moore and others, 1991; Dark and Allen, 2005; Finsinger and Tinner, 2005; Maher and others, 2012; Brugger and others, 2016; Campbell and others, 2016; Rey and others, 2017). This allows quantitative pollen concentration and influx estimates (Stockmarr, 1971; Birks and Gordon, 1985), which cannot be achieved otherwise unless the entire sample is counted (von Post, 1916; Welten, 1944; Moore and others, 1991).…”

Environmental Drivers of Holocene Forest Development in the Middle Atlas, Morocco

“…A series of standard preparation treatments were employed, specifically: (i) addition of Lycopodium tablets to enable the calculation of pollen concentrations (Stockmarr, 1971); (ii) KOH digestion to remove humid acids; (iii) sieving at 180 µm to remove coarse material; (iv) removal of siliceous material using either HF digestion or dense-media separation with sodium polytungstate (SPT); and (v) acetolysis to destroy cellulose. At stage (iv) SPT was selectively applied to improve concentration of organic material in the upper part of the sequence, following rigorous testing to ensure that no bias is imparted in terms of pollen type recovery (Campbell et al, 2016). Residues were dehydrated in alcohol and mounted using silicon oil.…”

Stable carbon isotope analysis on fossil Cedrus pollen shows summer aridification in Morocco during the last 5000 years

“…As traditional pollen preparation techniques (notably acetolysis) can alter the geochemical signal due to carbon-bearing chemicals (Loader and Hemming, 2004;Descolas-Gros and Schölzel, 2007;Nelson, 2012), a new technique based on micro-sieving (Heusser and Stock, 1984;Brown et al, 1989), sodium pyrophosphate washes (Bates et al, 1978) and dense media separation (Nakagawa et al, 1998;Campbell et al, 2016;Fletcher et al, 2017) was used to isolate pollen. The first stage involves concentration of the target pollen grains (summarized in Fig.…”