Abstract
Acid mine drainage (AMD) often contains high concentration of iron (Fe), which can exceed 100 mg/L, while speciation and precipitation are key factors controlling the removal efficiency of Fe and other elements. This study monitored seasonal variations in AMD quality at A mine, Japan (pH: 2.6–3.2, Total-Fe: 128–162 mg/L), and found the dominant dissolved Fe species shifted from ferrous ion (Fe(II)aq) in summer to ferric ion (Fe(III)aq) in winter. Neutralization experiments using simulated AMD containing either Fe(II)aq or Fe(III)aq revealed that initial Fe speciation had little effect on arsenic and copper removal efficiency at this site. Furthermore, the reaction experiments using natural AMD in the presence or absence of Fe precipitates (5 v/v%) revealed the Fe(II)aq oxidation rate was 3 × 105 and 8 × 105 times higher in the presence of Fe precipitates at pH 3.0 and 3.5, respectively. Fe(II)aq oxidation was reduced substantially when using autoclaved Fe precipitates, suggesting that Fe(II)aq oxidation might be enhanced by processes associated with Fe precipitates, including microbial activity, rather than by homogeneous chemical oxidation alone. Therefore, promoting interaction between AMD and Fe precipitates, together with slight pH adjustment, could be effective for Fe removal from AMD at A mine.
Acknowledgements
The SEM-EDS analysis was performed at the Joint Research Center for Environmentally Conscious Technologies in Materials Science at ZAIKEN, Waseda University. We thank James Buxton MSc, from Edanz (https://jp.edanz.com/ac), for editing a draft of this manuscript.
Funding
This study was supported by Nihonkaisui Co., Ltd. and Japan Organization for Metals and Energy Security (JOGMEC)
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
Competing interests
The authors declare no competing interests.
Additional information
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
Reprints and permissions
About this article
Cite this article
Fuchida, S., Nakamura, A., Kato, S. et al. Seasonal variation in water quality and evaluation of optimal iron removal conditions in acid mine drainage at A mine, Japan.
Sci Rep (2026). https://doi.org/10.1038/s41598-026-73325-w
Received:
Accepted:
Published:
DOI: https://doi.org/10.1038/s41598-026-73325-w
Keywords
- Acid mine drainage
- Seasonal monitoring
- Iron removal
- Geochemical modeling
- Schwertmannite
Source: Ecology - nature.com
