TY - JOUR
T1 - Humic Substances Facilitate Arsenic Reduction and Release in Flooded Paddy Soil
AU - Qiao, Jiangtao
AU - Li, Xiaomin
AU - Li, Fangbai
AU - Liu, Tongxu
AU - Young, Lily Y.
AU - Huang, Weilin
AU - Sun, Ke
AU - Tong, Hui
AU - Hu, Min
N1 - Funding Information:
This work was supported by funding from the National Natural Science Foundation of China (41330857 and 41877043), Guangdong Natural Science Fund for Distinguished Young Scholars (2017A030306010), Guangdong Academy of Sciences’ Projects (2019GDASYL-0103050, 2018GDASCX-0501, and 2017GDASCX-0106), and Guangdong Special Support Plan for High-Level Talents (X.L.).
Publisher Copyright:
© 2019 American Chemical Society.
PY - 2019/5/7
Y1 - 2019/5/7
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=85064806172&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85064806172&partnerID=8YFLogxK
U2 - 10.1021/acs.est.8b06333
DO - 10.1021/acs.est.8b06333
M3 - Article
C2 - 30942579
AN - SCOPUS:85064806172
SN - 0013-936X
VL - 53
SP - 5034
EP - 5042
JO - Environmental Science and Technology
JF - Environmental Science and Technology
IS - 9
ER -