Abstract
The composition and structure of dissolved organic matter (DOM) are sensitive indicators that guide the water infiltration process in soil. The DOM chemical composition in seepage affects river water quality and changes soil organic matter (SOM). In this lysimeter test study, fluorescence spectra and optical indices were used to examine the interaction between the percolation water (P-W) and leachate water (L-W) DOMs affected by the soil solution (S-S). The L-W DOM had a higher aromaticity (SUVA254), average molecular weight (S275-295) and terrestrial source (fluorescence index (FI)), but fewer autochthonous sources (biological index (BIX)) than the P-W DOM. Organic carbon standardization (OCS) and protein- (PLF), fulvic- (FLF) and humic-like fluorescence (HLF) intensity showed that L-W DOM increased 44%, 55% and 81%, respectively, compared to the P-W DOM. The linear regression slopes between OCS FLF and PLF were 0.62, 1.74 and 1.79 for P-W, L-W and S-S, respectively. The slopes between OCS HLF and PLF were 0.15, 0.58 and 0.64 for P-W, L-W and S-S, respectively. The P-W DOM was in contact with the soil litter layer, where S-S labile lignin phenolic compounds released and dissolved into the L-W DOM. This increased its aromaticity, and extent of humification.
Highlights
Dissolved organic matter (DOM) is an important component of water; it changes drinking water quality and reduces water treatment efficiency [1,2]
Concentrations of deep groundwater were much lower than dissolved organic carbon (DOC) concentration in rainwater and surface water; the deep groundwater DOC concentration was significantly reduced compared to the surface water DOC concentration
The results showed that percolation water (P-W), leachate water (L-W) and soil solution (S-S) had a significant
Summary
Dissolved organic matter (DOM) is an important component of water; it changes drinking water quality and reduces water treatment efficiency [1,2]. The chemical composition of DOM and SOM were examined by the fluorescence intensity and ratio change in the three regions [26,27]. Research on the percolation water (P-W) DOM in shallow infiltration and lateral seepage affected by the SOM chemical composition and structure is still lacking. In this study, using a medium-scale lysimeter, optical indices (UV-Vis and fluorescence) and fluorescence spectroscopy were used to examine the chemical structure and composition relationship between P-W and leachate water (L-W) DOM as well as extracted soil organic solution (S-S). The aromaticity, average molecular weight and the terrestrial and autochthonous contributions were used to examine the P-W and L-W DOM as well as the S-S with optical indicators SUVA254 , S275-295 , FI and BIX, respectively. The chemical structure and composition differences between P-W and L-W DOM and how they were affected by the S-S were discussed
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