Comparing the Heterogeneity of Copper-Binding Characteristics for Two Different-Sized Soil Humic Acid Fractions Using Fluorescence Quenching Combined with 2D-COS
Figure 2
Synchronous 2D spectrum for (a) the 1–10 K fraction and (b) the >100 K fraction. Asynchronous 2D spectrum for (c) the 1–10 K fraction and (d) the >100 K fraction of the soil HA. The arrows indicate the main peaks of the spectra, based on which the copper-binding parameters were calculated in Table 2. The - or -axis represents the excitation wavelength of the synchronous fluorescence spectra. The solid and the dashed lines represent the positive and negative signs, respectively.
