Date of Award

10-30-2020

Publication Type

Master Thesis

Degree Name

M.Sc.

Department

Earth and Environmental Sciences

Keywords

FeHEDTA, magnetic methods, magnetic Susceptibility, soils

Supervisor

Maria T. Cioppa

Rights

info:eu-repo/semantics/openAccess

Abstract

Industrial, agricultural and urban activities may introduce anthropogenic pollutants into the local, regional and/or global environment. As soils can accumulate these pollutants, soil monitoring can be used in environmental assessments. Geophysical methods are used to provide rapid, nondestructive, and diagnostic soil monitoring. Magnetic methods are often used; however, environmental magnetic studies of soils have other purposes, including the study of climate variations and soil forming processes. This study examined the effects of a common iron-based herbicide (iron hydroxylethylenediaminetriacetic acid aka FeHEDTA) on soil magnetic properties. The magnetic properties of FeHEDTA control samples in varying concentrations (5-50% by weight in gypsum powder), untreated specimens from soils of Windsor-Essex County (Ontario Canada) and FeHEDTA-treated specimens from the same soils were examined. Magnetic susceptibility (χlf, χhf), frequency-dependent magnetic susceptibility (χfd), artificial remanence analysis (isothermal and anhysteretic), and hysteresis measurements were used to determine the extent of the FeHEDTA effects. The results indicate that: 1) FeHEDTA additions of >26% by weight to the gypsum powder resulted in a magnetic signature characteristic of superparamagnetic magnetite; 2) the effect of FeHEDTA is most evident in soils with comparatively lower initial magnetic mineral concentrations; and, 3) the effect of FeHEDTA in clay rich soils was an increase in χfd, suggesting that the FeHEDTA was reacting with clay minerals to increase the iron concentration in treated soil samples. The results suggest that the standard application dose of FeHEDTA for weed-killing would have negligible effects on soil; however, over-application or direct application to soil could result in a small measurable effect.

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