Origin traceability of Santalum album wood using stable isotope and mineral element methods
The purpose of this study is to analyze the feasibility of tracing the origin of woods using methods of stable isotopes and mineral elements,and to clarify the influence of heartwood and sapwood on the accuracy of wood origin identification.Santalum album wood samples from major growing areas of China,namely,Dongfang of Hainan Province,Zhanjiang and Zhaoqing of Guangdong Province,were selected as the research objects.Five stable isotope ratios(δ13C,δ2H,δ18O,δ15N and δ34S)and 38 mineral elements'contents in heart wood and sapwood samples were examined by the stable isotope ratio mass spectrometer(EA-IRMS)and inductively coupled plasma mass spectrometer(ICP-MS),and the origin discrimination was carried out by the stoichiometric method.The results showed that there were significant differences in the ratio of three stable isotopes and the content of 25 mineral elements between sapwood and heartwood.The accuracy of origin discrimination using the S.album sample set with the same radial position was better than that of the wood sample set(without distinguishing the sapwood and heartwood),which indicated that the sampling position should be fully considered in practical applications to achieve the optimal origin discrimination efficiency.The orthogonal partial least squares discriminant analysis(OPLS-DA)showed that the accuracy of mineral element method was 86.54％-100.00％,which was significantly better than the stable isotope method(51.32％-60.00％).However,the method based on the combination of the isotope ratio and mineral element content did not significantly improve the accuracy of origin discrimination(88.46％-100.00％).Due to the complexity of influence factors and mechanisms of stable isotopes and mineral elements during tree growth,further studies are needed.The clarity of these influencing factors or mechanisms will provide an important scientific basis for better understanding of the difference in the accuracy rate of origin tracing by different methods and different markers.It is shown that two stable isotopes(δ2H and δ15N)and 14 mineral elements(Sb,Mo,Cr,Pd,V,Cs,Rb,Sn,As,Ni,Co,Pb,Cd and Fe)were the key indicators to trace the origin of S.album woods.This study provides a feasible solution to the problem of tracing the origin of S.album woods in large-scale geographic space.In the future,more samples of S.album from Chinese origin and other countries will be added,multiple copies,multiple data,multiple types of indicators will be combined and a variety of innovative algorithms will be utilized to solve the difficulties of accuracy,reliability and stability,especially for wood origin tracing with small geographical distances,and to provide technical support for combating illegal timber harvesting and conserving species diversity.
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维普
