Document Type

Thesis

Abstract

The goal of this study is to determine whether Jamestown groundwater accounted for the extreme mortality rates experienced by the earliest settlers to the colony in 1607, due to ingestion of naturally-occurring aqueous arsenic, and iron. Modern analyses of groundwater collected from the local aquifer yield data concordant with Rowland (2012) which show high concentrations of iron and low to moderate levels of arsenic. Values are compared to World Health Organization guidelines for drinking water quality to determine the lethality of the modern groundwater, serving as a proxy for the colonial groundwater and therefore, drinking water, system. Though iron and arsenic pose a potential threat to human health, salinity and bacterial activity serve to exacerbate the affects of these species and are factors known to greatly affect the dynamic nature of the groundwater system. The Pitch and Tar swamp is the source of the dissolved iron and arsenic and is produced via microbially-mediated reductive processes occurring within the organic-rich swamp which lower the valence state of metal ions, increasing their solubility. Dissolved arsenic production within the swamp dwarfs dissolved iron concentrations, indicating alternative arsenic sources, such as in naturally occurring, arsenic-bearing minerals in local sediments. Additionally, arsenic concentrations vary temporally and seasonally, with ‘hotpots’ occurring in areas far from the swamp. A general down-gradient distribution of species originating from the swamp persists and is largely affected by precipitation showing that physical rather than chemical processes control the presence, distribution and mobilization of arsenic, iron and salts in the Jamestown groundwater system.

Date Awarded

2013

Department

Geology

Advisor 1

James M. Kaste

Advisor 2

Gregory S. Hancock

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