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A procedure that modifies standard preparation techniques was developed to concentrate pollen and spores from intractable sediments. These modifications include sieving samples suspended in 0.001 M sodium pyrophasphate through 7ìm nylon screens prior to and following chemical treatments. If siliceous sediments require reprocessing with hydroflouric acid (HF), samples are sieved through 7 ìm screens between HF treatments, using sodium pyrophosphate as a suspension. Samples with large amounts of undigested, fine‐grained organic matter are slowly oxidized with a sodium chlorate mixture. Continuously monitored use of these techniques produces statistically‐significant sums of pollen from sediments which otherwise would be of little value to palynologists.
Heusser et al. (Sat,) studied this question.