Archaeopalynological preparation techniques

The pollen preparation technique consists of a sequence of steps that allow for the removal of organic and inorganic matter from a sample, with the aim of rendering the grains visible under the microscope and enabling easy identification and counting. No special equipment is required, but particular care is needed to avoid contamination of fossil with fresh pollen, and in the use of hazardous chemical products. It is also desirable that all the samples from a stratigraphic sequence be processed using the same procedure in order to avoid different preparation techniques affecting the final results and interpretation of pollen data. Here we describe the standard minimum procedure necessary to extract pollen from archaeological sediments, based on successive treatments with HCl, HF, and NaOH, and a number of modules that can be additionally applied, depending on the composition of the analyzed material. Sieving will be used if the sample composes of a large fraction of sediment coarser than 200 μm or finer than 8 μm. Deflocculation will be applied if the sediment is especially high in clay content. Gravity separation is convenient when samples are poor in pollen and contain very high amounts of mineral fragments. Acetolysis is the last step of the pollen preparation if the samples still contain significant amounts of undissolved organic matter that may affect pollen identification and counting.