UPWASH AND DOWNWASH OF POLLEN AND SPORES IN THE UNSATURATED SURFACE LAYER OF SPHANGNUM-DOMINATED PEAT

Area of Science:

• Palynology
• Geology
• Environmental Science

Background:

• Understanding pollen and spore transport in peat is crucial for paleoenvironmental reconstructions.
• The influence of hydrological processes on microfossil distribution in organic sediments remains understudied.

Purpose of the Study:

• To investigate the vertical movement of Corylus and Cedrus pollen and Lycopodium spores in Sphagnum and peat.
• To determine the effect of different water flow regimes and sediment packing on microfossil displacement.

Main Methods:

• Factorial experiment involving four flow regimes (no flow, downward, upward, alternate), three injection depths (1, 5, 9 cm), and three packing types (natural, hand-packed, haphazard).
• Experiment duration of 36 days with Corylus, Cedrus pollen, and Lycopodium spores in Sphagnum and peat.
• Results corrected for compaction and differential recovery, though main findings were unaffected.

Main Results:

• Downward, upward, and alternating water flows displaced the median pollen position by approximately 1.5 cm.
• Flow regimes increased the interquartile span by 2 cm, with about 25% of grains moving at least 3 cm.
• Upward flow velocity likely exceeds the sinking rate of pollen and spores in unsaturated zones.

Conclusions:

• Water flow is a significant factor influencing vertical pollen and spore transport in peat.
• Flow reversals may play a role in dislodging and re-suspending microfossils within sediment channels.
• These findings have implications for interpreting fossil pollen records and understanding sediment dynamics.