T257 Geomorphology of Human-Altered Landscapes (Posters)

Tuesday, 24 October 2017
9:00 AM - 6:30 PM
Halls 4EF

SPATIAL VARIATION IN GEOCHEMICAL SIGNATURES OF THE ANTHROPOCENE IN NORTHEASTERN US

Paper number: T257-3
Program: Technical Sessions
Time: 9:00 AM – 6:30 PM

Authors

Abstract

As geochemistry becomes a critical tool for defining anthropogenic influence on Earth systems and geomorphic processes, there is a need to understand the variation between geochemical signatures of human impacts in a variety of landscapes across the globe. Furthermore, within a given region, it is important to identify variation in the signatures recorded in terms of signal strength and preservation, as this will influence interpretation of the onset of human activity at specific sites. New data from sediment cores collected throughout Connecticut provide a direct comparison between upland and lowland near surface geochemistry from the time of European settlement in the 17th century to the present. Sediment cores from upland wetlands, floodplains, and coastal estuaries were sampled and analyzed using X-ray fluorescence (primarily focused on lead, copper, and zinc) and a DMA-80 (for direct mercury measurement). These metals have been shown to be reliable indicators of industrial activity. Metal concentrations for upland environments are consistently less than concentrations in lowland coastal settings, with the greatest disparities in lead and mercury. Greater values in coastal Connecticut are likely due to preferential human settlement in coastal environments and along large waterways prior to occupying upland environments, therefore metal sources are more likely to be incorporated into the sedimentary archive. Additionally, the coastal estuaries are connected to rivers with large drainage basins, and consequently are more likely to have greater signal strength and preservation. Overall, this work highlights the critical importance of distinguishing geochemical signatures across geographic locations to accurately assess the variable onset of anthropogenic influence on the landscape, hence diagnosing the Anthropocene.

Geological Society of America Abstracts with Programs. Vol. 49, No. 6

doi: 10.1130/abs/2017AM-308184

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