Two-dimensional dynamic correlation feature enhancement and exceedance discrimination of near-infrared and ultraviolet-visible spectra for nitrogen-containing farmland leachate

Résumé fourni par la source

To address the difficulty in rapidly and accurately identifying excessive nitrate nitrogen and ammonium nitrogen in nitrogen-containing farmland leachate against the complex background of soil leachate, near-infrared (NIR) and ultraviolet-visible (UV-Vis) spectra were acquired, and a nitrogen exceedance discrimination method based on two-trace two-dimensional correlation spectroscopy (2T2D-COS) and N-way partial least squares discriminant analysis (NPLS-DA) was developed. The results showed that 2T2D-COS effectively revealed weak spectral features and their dynamic variation relationships that were difficult to distinguish in one-dimensional spectra of complex systems. For nitrate nitrogen, synchronous spectra achieved better modeling performance for both NIR and UV-Vis data, with test accuracies of 94.55% and 88.46%, respectively. For ammonium nitrogen, asynchronous spectra performed slightly better in NIR, whereas synchronous spectra still performed better in UV-Vis, with both test accuracies reaching 87.50%. Overall, NIR spectroscopy showed better stability and greater robustness to background interference than UV-Vis. These results provide a new methodological reference for the rapid exceedance discrimination of nitrogen-containing farmland leachate.