Variable effects of soil organic matter on arsenic behavior in the vadose zone under different bulk densities

Tho Huu Huynh Tran, Sang Hyun Kim, Hosub Lee, Ho Young Jo, Jaeshik Chung, Seunghak Lee

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


The nonstationary nature of water and oxygen content in the vadose zone determines various biogeochemical reactions regarding arsenic (As) therein, which affects the groundwater vulnerability to As contamination at a site. In the present study, we evaluated the effect of soil organic matter (OM) on the behavior of As using specifically designed soil columns that simulated the vadose zone. Three wet-dry cycles were applied to each of the four columns with different OM contents and bulk densities. OM was found to exhibit variable effects, either inhibiting or accelerating the mobilization of As, depending on bulk density. At a moderate bulk density (< 1.27 g/cm3), OM slightly lowered the pH of pore water, which enhanced the sorption of As onto the iron (Fe) oxides, promoting the retention of As in soil. In the soil column with a relatively higher bulk density (1.36 g/cm3), however, the dissimilatory reduction of iron oxides was triggered by rich OM under oxygen-limited conditions. X-ray absorption spectroscopy analysis revealed that alternate wetting and drying transformed the Fe oxides in the soil by reductive dissolution and subsequent re-precipitation. Consequently, As was not stably retained in the soil, and its mobilization downwards was further accelerated.

Original languageEnglish
Article number130826
JournalJournal of hazardous materials
Publication statusPublished - 2023 Apr 5

Bibliographical note

Funding Information:
This study was supported by the Korea Environment Industry & Technology Institute (KEITI) through the Subsurface Environment Management (SEM) Projects ( 2018002440006 , 2020002440002 , and 2021002470004 ) funded by the Korea Ministry of Environment (MOE), and by the National Research Foundation of Korea (NRF) through the ‘Climate Change Impact Minimizing Technology’ Program funded by the Korean Ministry of Science and ICT (MSIT) ( 2020M3H5A1080712 ). The authors also acknowledge support from the Future Research Program ( 2E31932 ) funded by the Korea Institute of Science and Technology (KIST). S. Lee was supported in part by the KU-KIST Graduate School Project.

Publisher Copyright:
© 2023 The Authors


  • Arsenic
  • Groundwater vulnerability
  • Soil organic matter
  • Vadose zone
  • Wet-dry cycle

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution
  • Health, Toxicology and Mutagenesis


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