Soil Heavy Metal Pb Content Estimation Method by Combining Field Spectra with Laboratory Spectra

  Objectives  The pollution of heavy metal has become increasingly serious in recent years. The accumulation of heavy metals in the soil will be a threat to ecological balance and human health. Therefore, we need to obtain heavy metal content in soil quickly and accurately.

  Methods  This paper proposes a method to combine field and laboratory spectra to construct a mechanism estimation model of soil lead (Pb). Firstly, direct standardization (DS) algorithm was employed to eliminate the influence of environmental factors on the field spectra. Secondly, in order to enhance the diversity of the samples, the laboratory spectra were introduced to joint modeling. Finally, the characteristic spectra of iron oxide were extracted for mod‍el‍ing to increase the model rationality.

  Results  This method was validated by the spectra of 70 soil samples from Xiong'an farming area in Hebei province. The accuracy R² of model established by full-band field spectra without DS correction was only 0.220 0. However, the accuracy R² of model established by the proposed method in this paper reached 0.914 6.

  Conclusions  It indicates that the model for estimating Pb content can be significantly improved by removing the influence of environmental factors on the field spectra, extracting the iron oxide characteristic spectra of the combining field spectra with laboratory spectra.