Spatial and seasonal variations of pollen in the Mississippi and Atchafalaya Rivers, United States of America (Louisiana).

摘要

The objective of this research is to develop a better understanding of the nature of transport and distribution of pollen in river systems. Interpretation of palynological data from sedimentary deposits requires an understanding of processes of pollen transport and deposition. The two studies reported here focus on questions arising from previous research, specifically the relationship of pollen concentration and distribution to flow velocity, distance from river bottom, and sediment supply.; The study reported in chapter 1 examines pollen concentrations and velocity data within a cross section of the Mississippi River at St. Francisville, Louisiana, to examine processes of pollen suspension and transport. Contrary to other reports, no significant correlation between pollen concentrations and flow velocity is found. Application of established theory of suspended particle transport to processes of pollen grain transport demonstrates that such relationships should not be expected in a river.; To establish potential sources of pollen in fluvially related sediment sequences, one should be concerned with the factors controlling formation of pollen load in a river throughout a year, the focus of chapter 2. This study examines the seasonal distribution of pollen load within a cross section of the Atchafalaya River at Morgan City, Louisiana. Analysis of suspended pollen in the Atchafalaya suggests that pollen production by upper basin and local vegetation and processes of movement and storage of sediment in the river system act together to alter the concentration and assemblages of suspended pollen. (Abstract shortened by UMI.)