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Total Organic Carbon (TOC) + Total Inorganic Carbon (TIC)

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Presentation on theme: "Total Organic Carbon (TOC) + Total Inorganic Carbon (TIC)"— Presentation transcript:

1 Total Organic Carbon (TOC) + Total Inorganic Carbon (TIC)
Total Carbon (TC) = Total Organic Carbon (TOC) + Total Inorganic Carbon (TIC) Calcite TOC preparation: ~0.25 g dry, powdered sample acidified in baked glass beaker with 1N 60 oC for hours filtered with de-ionized water to flush out Cl- onto a baked glass fiber filter transferred to a crucible boat for drying and elemental analysis

2 Trace elements coprecipitated minerals and soil organic matter (SOM)
with secondary soil minerals and soil organic matter (SOM) Solid Coprecipitated trace elements Fe and Al oxides B, P, V, Mn, Ni, Cu, Zn, Mo, As, Se Mn oxides P, Fe, Co, Ni, Zn, Mo, As, Se, Pb Ca carbonates P, V, Mn, Fe, Co, Cd Illites B, V, Ni, Co, Cr, Cu, Zn, Mo, As, Se, Pb Smectites B, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Pb Vermiculites Ti, Mn, Fe Organic matter Al, V, Cr, Mn, Fe, Ni, Cu, Zn, Cd, Pb, P, N

3 CCS north-facing CCN south-facing

4 X-ray fluorescence (XRF)
The technology was developed in the 1950’s.

5 X-ray fluorescence (XRF):
The emission of characteristic "secondary", or fluorescent, X-rays from a material that has been excited by bombarding with high-energy X-rays or gamma rays.

6 Irradiating an atom with high-energy primary X-ray photons delivers sufficient energy for an electron to be ejected completely out of the atom. An outer shell L electron falls inward to fill the void created in the inner shell, and an X-ray characteristic of the atom's elements is emitted.

7 X-ray fluorescence (XRF) spectrometers
Schematic arrangement of wavelength dispersive spectrometer. Bragg’s Law nλ= 2d * sinΘ Schematic arrangement of energy dispersive spectrometer The dispersion and detection are a single operation. Proportional counters or various types of solid state detectors (PIN diode, Si(Li), Ge(Li), Silicon Drift Detector SDD) are used.

8 Schematic arrangement of a wavelength-dispersive (WD) X-ray fluorescence (XRF) spectrometer
B.

9 Various types of detectors most commonly gas flow proportional and scintillation are used to measure the intensity of the emitted beam on bench top models. Gas flow proportional counters are used mainly for detection of longer wavelengths (lighter elements). The gas is usually 90% argon, 10% methane ("P10"). The argon is ionized by incoming X-ray photons, and the electric field multiplies this charge into a measurable pulse. The methane suppresses the formation of fluorescent photons caused by recombination of the argon ions with stray electrons. Scintillation counters consist of a scintillating crystal (typically of sodium iodide doped with thallium) attached to a photomultiplier. The crystal must be protected with a relatively thick aluminum/beryllium foil window, which limits the use of the detector to wavelengths below 0.25 nm. Typically used for heavier elements. Scintillation - a flash of light produced in certain materials when they absorb ionizing radiation. B. A.

10 Pressed Powder Disks/Pellets
To obtain good XRF results using the pressed powder technique, control of particle size is absolutely critical. Used primarily for trace elements and uniform samples compositions.

11 For Major Oxide Analysis
Fused Glass Disk For Major Oxide Analysis Lithium metaborate flux + sample in a 7:1 proportion Fusion in Pt crucible > 750 oC Fused glass disk from gold or brass mould

12 Resistance to Abrasion
Sample Preparation Typical Composition of Grinding Units Material Major Elements Minor Elements Hardness (Mohs) Resistance to Abrasion Durability Hardened Steel Fe Cr, Si, Mn, C 5.5-6 Moderate High Stainless Steel Fe, Cr Ni, Mn, S, Si 5-5.5 Cr-free Steel C, Mn, Si, Mo Tungsten Carbide W, C, Co Ta, Ti, Nb 8.5 + Long-wearing, but brittle Alumina Ceramic Al Si, Ca, Mg 9 Very High Agate Si Al, Na, Fe, K, Ca, Mg 8.5 Extremely High Very long-wearing, but brittle Zirconia Zr Hf, Mg Very long-wearing Silicon Nitride Y, Al, Fe, Ca Plastic C -- 1.5 Low Low, but disposable Available in the Department

13 Trace Elements Zr Sr Rb Cr Nb Pb Ni Y Zn Co Major Oxides Cu W Mo Th
Detection limit 2 ppm: Zr Sr Rb Cr Nb Pb Ni Y Zn Co Detection limit 5 ppm: Cu W Mo Th Detection limit 10 ppm: U V Detection limit 50 ppm: Ba Major Oxides Detection limit %: Al2O3 CaO Fe2O3 K2O P2O5 Na2O MnO MgO TiO2 SiO2 Loss On Ignition (LOI) is carried out at 1000oC. Removes volatiles including carbon, sulfur and nitrogen compounds, and structural and adsorbed water (H2O). Detection limit %: LOI wt.% = (sample weight - residue weight) * 100 sample weight

14 Laboratory Bench-top Models
Field Hand-held Models

15 Linear Regressions for Select Trace Elements
using Standard Reference Materials (SRMs)

16

17 PD Soil Profile Profile Horizons Core #1 Major Oxide
Concentrations (wt.%) Trace Elements Concentrations (ppm) Al2O3 A AB Bt Bxta Bxtb II Bt II Bx II Bx2 Fe2O3 Na2O MgO Profile Horizons Zr Sr V 5 10 15 20 100 200 300 400 500

18 PD Soil Profile Profile Horizons Core #1 Major Oxide
Concentrations (wt.%) Trace Elements Concentrations (ppm) Al2O3 A AB Bt Bxta Bxtb II Bt II Bx II Bx2 Fe2O3 Na2O MgO Profile Horizons Zr Sr V 5 10 15 20 100 200 300 400 500


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