Nuclear Methodology for Non-Destructive Multi-Elemental Analysis of Large Volumes of Soil

Neutron-Stimulated Gamma Ray Analysis of Soil

“…This new method is based on measuring the gamma response of soil irradiated with fast neutrons. One modification of this method, PFTNAPulsed Fast/Thermal Neutron Analysis, has been shown to provide wide-area monitoring for prolonged periods [15,53]. The result of measurements using this method gives, as will be demonstrated below, the values of average carbon content in weight percent in the upper soil layer (thickness~10 cm) of~1.5 m 2 area centered under the neutron source.…”

“…[15] reported that the value of the carbon signal in INS spectra was connected to the surface density of carbon in a 30-cm layer. Figure 19 shows three carbon depth profiles in modeled sand-carbon mixtures for which the values of SD(30) are all equal to 2.29 gC cm…”

“…Neutron penetration depth and gamma flux attenuation are determined by soil properties. The distribution of soil carbon with depth is usually nonuniform (i.e., carbon level decreases as depth increases) and by first approximation can be described by exponential law [15]. The parameters of these distributions vary from site to site [56].…”

“…Furthermore, DCT soil analysis represents a point measurement in space and time that cannot be confidently extrapolated to field or landscape scales which limits its utility for expansive coverage or longer timescale interpretation. Other techniques include laser-induced breakdown spectroscopy, near-and mid-infrared spectroscopy, diffuse reflectance infrared Fourier transform spectroscopy, and pyrolysis molecular beam mass spectrometry [15].…”

“…This method is based on detecting 4.44-MeV gamma rays issued from carbon nuclei excited by fast neutrons promptly after the interaction [15]. Accurate quantification of soil carbon is important since it is an indicator of soil quality [16] that can affect soil carbon sequestration, fertility, erosion, and greenhouse gas fluxes [17][18][19][20].…”