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Crop and Soil Sciences Calendar

Seminar – Aakriti Sharma, Soil Science PhD Student

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November 8, 2017 @ 3:40 pm - 5:00 pm

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Title: “Modeling Microscale Accumulation and Speciation in Complex Soil Matrices”

Soil Science Seminar on Wednesday, 08 November, 2017 will be presented by Aakriti Sharma, Soil Science PhD Student, Crop & Soil Science Department, NCSU.

Pre-seminar refreshments are served at 3:15 pm in the McKimmon Room (2223 WMS). Seminar begins at 3:40 pm in Williams Hall Auditorium (2215 WMS). Everyone is welcome to attend.

Abstract
Soils regulate the fate of potentially toxic trace elements in the environment, but models of trace-element retention and mobilization are confounded by the complexity of these multicomponent systems. Our goal is to determine how the micro- and nano-scale complexities of soil geochemistry affect the binding of potentially toxic trace elements, particularly arsenic. Our objective was to quantify spatial relationships among elements within microsites of a soil matrix and determine whether it affected arsenate accumulation and speciation. X-ray fluorescence microprobe images were collected across a 100 µm x 100 µm region before and after treating an oxide-coated quartz sand grain with 0.1 mM As(V) solution. Spatial statistical models developed to analyze multi-element colocalization on the mineral-organic coating of an As(V)-treated soil sand grain showed a dominance of Fe in describing the microscale spatial patterns of As(V) accumulation. In addition, a significant interaction (α = 0.05) of Fe with Ti and Ca in predicting As accumulation was also found. Similarly, to determine chemical speciation of accumulated As, As K-edge microscale X-ray- absorption near edge structure (µ-XANES) were collected from selected hotspots across the full image and within a 10 µm x 10 µm region of varying elemental composition. Linear combination fits of these spectra indicated localized variation in As speciation, and the speciation was related to the elemental composition. In essence, significant interactions of Fe with Ti and Ca on arsenate accumulation suggest that multiple co-localized components in soil microsites may affect the reactivity of trace elements in soils.

 

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Date
November 8, 2017
Time
3:40 pm - 5:00 pm
Event Categories:
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Location
2215 Williams Hall Auditorium
101 Derieux Place
Raleigh, 27695 United States

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