Humic Substances Facilitate Arsenic Reduction and Release in Flooded Paddy Soil

Jiangtao Qiao, Xiaomin Li, Fangbai Li, Tongxu Liu, Lily Y. Young, Weilin Huang, Ke Sun, Hui Tong, Min Hu

Research output: Contribution to journalArticlepeer-review

101 Scopus citations


Organic matter is important for controlling arsenic reduction and release under anoxic conditions. Humic substances (HS) represent an important fraction of natural organic matter, yet the manner in which HS affect arsenic transformation in flooded paddy soil has not been thoroughly elucidated. In this study, anaerobic microcosms were established with arsenic-contaminated paddy soil and amended with three extracted humic fractions (fulvic acid, FA; humic acid, HA; and humin, HM). The HS substantially enhanced the extent of arsenic reduction and release in the order FA > HA > HM. It was confirmed that microbially reduced HS acted as an electron shuttle to promote arsenate reduction. HS, particularly FA, provided labile carbon to stimulate microbial activity and increase the relative abundances of Azoarcus, Anaeromyxobacter, and Pseudomonas, all of which may be involved in the reduction of HS, Fe(III), and arsenate. HS also increased the abundance of transcripts for an arsenate-respiring gene (arrA) and overall transcription in arsenate-respiring Geobacter spp. The increase in both abundances lagged behind the increases in dissolved arsenate levels. These results help to elucidate the pathways of arsenic reduction and release in the presence of HS in flooded paddy soil.

Original languageEnglish (US)
Pages (from-to)5034-5042
Number of pages9
JournalEnvironmental Science and Technology
Issue number9
StatePublished - May 7 2019

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Environmental Chemistry


Dive into the research topics of 'Humic Substances Facilitate Arsenic Reduction and Release in Flooded Paddy Soil'. Together they form a unique fingerprint.

Cite this