A simple method to separate pollen for AMS radiocarbon dating and its application to lacustrine and marine sediments

We present a simple method for manually separating pollen concentrates for radiocarbon accelerator mass spectrometry (AMS) dating using a mouth pipett ing system. The required equipment is readily available from scientific equ ipment supply houses at minimal cost. Pollen samples from lake sediments re quired about 4 h of hand picking, whereas samples from marine sediments req uired about 8 h labor. Pollen dates from marine sediments were much older t han expected. We are attempting to resolve whether this is due to contamina tion of the pollen or the presence of significant quantities of old reworke d pollen. Pollen dates from lake sediments associated with Mazama Ash were consistent with other published ages; however, replicate dates on pollen sa mples from above the ash were consistently older than the surrounding sedim ent. Our results suggest that caution must be used when interpreting pollen dates if the potential for sediment reworking is present.