22-27 September 2019
Trade Fairs and Congress Center (FYCMA)
Europe/Madrid timezone

Quantity and Quality Variations of Dissolved Organic Matter (DOM) in Column Leaching Process from Agricultural Soil: Hydrochemical Effects and DOM Fractionation

23 Sep 2019, 18:00
15m
Multiuses room 3 ()

Multiuses room 3

Oral Topic 5.3 - Advanced modelling tools for subsurface hydrology: from the vadose zone to deep environments Parallel

Speaker

Mr Wenlong Gu (Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences)

Description

Quantity and quality variation of dissolved organic matter (DOM) leached from agricultural soil are influenced by the chemistry of irrigation water. In this study, multiple spectroscopy methods were used to investigate the leaching dynamics and fractionation of DOM by utilizing selected solutions. The results showed that the Na solutions were more effectively in leaching DOC than the Ca solution, despite the additional contributions of the ligand exchange of SO42- and the hydrolysis of HCO3-. Furthermore, the aromaticity and molecular weights of DOM leached by Na solutions increased with the leaching, whereas contrary trends were reared by Ca, indicating specific cation substantially affects DOM concentration and composition. Six PARAFAC components were determined and showed different fractionation characteristics. (1) The long-wavelength, humic-like components (i.e., C1, C3, and C5) were largely accumulated at the early water saturating stage but attenuated toward dynamic stability in the salt-solution leaching (SSL) stage. (2) Reactive functional group-related humic-like components (i.e., C2, and C4) remarkably increased in response to the solutions chemistry. (3) The protein-like component (i.e., C6) was released with insignificant dynamic differences among the solutions. Despite the approximately stable DOC concentration at the late SSL stage, the varying kinetic characteristics constrained by the hydrochemistry were discerned for the DOM components. Especially for the humic-like components (C1-C5), which increased remarkably and had higher fluorescence intensities (Fmax) under sodium condition while declined under calcium condition, suggesting different types of releases process. Therefore, the methods used in this study identified the dynamic changes in DOC concentration, composition and kinetic factors, such as release rate and production-limited process, which offer promising advantages in monitoring DOM transport and fractionation in dynamic leaching process.

Primary authors

Mr Wenlong Gu (Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences) Dr Shuangbing Huang (Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences)

Co-authors

Ms Shan Lei (Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences) Mr Jun Yue (Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences) Mr Zhaoxin Su (Hebei GEO University, China) Mr Fei Si (Chengdu University of Technology, China)

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