Solid-phase cadmium speciation in soil using L3-edge XANES spectroscopy with partial least-squares regression.
Cadmium (Cd) has a high toxicity and resolving its speciation in soil is challenging but essential for estimating the environmental risk. In this study partial least-square (PLS) regression was tested for its capability to deconvolute Cd L(3)-edge X-ray absorption near-edge structure (XANES) spectra of multi-compound mixtures. For this, a library of Cd reference compound spectra and a spectrum of a soil sample were acquired. A good coefficient of determination (R(2)) of Cd compounds in mixtures was obtained for the PLS model using binary and ternary mixtures of various Cd reference compounds proving the validity of this approach. In order to describe complex systems like soil, multi-compound mixtures of a variety of Cd compounds must be included in the PLS model. The obtained PLS regression model was then applied to a highly Cd-contaminated soil revealing Cd(3)(PO(4))(2) (36.1%), Cd(NO(3))(2)·4H(2)O (24.5%), Cd(OH)(2) (21.7%), CdCO(3) (17.1%) and CdCl(2) (0.4%). These preliminary results proved that PLS regression is a promising approach for a direct determination of Cd speciation in the solid phase of a soil sample.
Institute for Land Use, University of Rostock, Justus-von-Liebig-Weg 6, 18051 Rostock, Germany.
Nina
N
Siebers
Jens
J
Kruse
Kai-Uwe
KU
Eckhardt
Yongfeng
Y
Hu
Peter
P
Leinweber
D002104:Cadmium / Q000737:chemistry* / Q000633:toxicity; D019187:Cadmium Compounds / Q000737:chemistry; D004787:Environmental Pollution; D016018:Least-Squares Analysis; D025341:Principal Component Analysis; D012015:Reference Standards; D012987:Soil; D012989:Soil Pollutants / Q000032:analysis* / Q000737:chemistry; D056928:X-Ray Absorption Spectroscopy
D019187:Cadmium Compounds; D012987:Soil; D012989:Soil Pollutants; D002104:Cadmium