5. CONCLUSIONS
In this study, six soil samples with different salt and SOM contents
were analyzed using LIBS, FTIR-ATR, and 2DCOS methods. The main
functional groups and salt-related metal elements were analyzed from
FTIR-ATR and LIBS spectra. The results revealed that the spatial
distribution of Mg and Ca showed a significant correlation, while Na and
K also showed a significant correlation. In samples with a lower SOM
content, Mg, Ca, Na, and K were distributed at the top of the ablation
area. However, the distributions broadened as the SOM content increased.
In samples with a lower SOM content, the SOM layer outside of the
mineral aggregate was thinner, nd the laser beam could ablate the
mineral after one or two shots. The hydrogen bonds in silicate groups
were stronger than those of organic functional groups, such as C=O/C=C,
when combined with salt-related compounds. Mg, Ca, Na, and K were not
originally from clay mineral compounds, but did partially originate from
organic functional groups.