Accumulation of aluminium and arsenic in Cenococcum geophilum sclerotia from forest soil affected by mining smoke

ABSTRACT

Aluminium toxicity may increase under low soil pH, and an increase in arsenic concentration in the soil may inhibit inorganic P uptake and influence fungal growth. This study investigated metals/metalloids accumulation in Cenococcum geophilum sclerotia collected from highly polluted forest soils affected by mining activities and smoke hazards. The Al and As concentrations in sclerotia were 11,700 ± 823 and 10.0 ± 1.29 mg kg⁻¹, respectively. TOF-SIMS ion mapping confirmed the predominant presence of Al as Al oxalate, acetate, and hydroxides, and the segregation of As showed higher intensities for organic As ions than inorganic As. Ion fragments of Al and As compounds were widely observed in sclerotial medulla and were generally elevated towards the central part coexisting with phosphoric acid ions. The mechanism of Al and As accumulation has been discussed to involve two biotransformation pathways in terms of sclerotial development using ¹⁴C dating. Because the sclerotia were significantly older than the historical smoke hazard and Al and As concentrations in sclerotia were high regardless of age, their accumulation were more likely to be promoted in the mature stage. This study provides insight into the contribution of ectomycorrhizal fungi and their sclerotia to soil ecosystems under metals/metalloids toxicity.

KEYWORDS:

• ICP-MS analysis
• TOF-SIMS analysis
• AMS ¹⁴C dating
• aluminium oxalate
• aluminium phosphate
• organic arsenic

Acknowledgements

We thank the Institute for Accelerator Analysis, Shirakawa, Japan for their cooperation in the ¹⁴C dating of the sclerotia.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contributions

N.K. and W.M. designed the study and conducted field-work, and N.K. wrote the draft. N.K., H.T., and G.A. performed the experiments. The manuscript was prepared based on discussions with all the authors.

Additional information

Funding

This study was supported by JSPS KAKENHI [grant number 17K077] to W.M. and by a PhD program research grant from the Tokyo Human Resources Fund for City Diplomacy 2019–2021, Tokyo Metropolitan Government, to N.K. and W.M.

Notes on contributors

Khulan Nyamsanjaa

Khulan Nyamsanjaa, DSc., Researcher at Botanic Garden and Research Institute, Mongolian Academy of Sciences. Environmental chemistry, environmental science. Orcid ID: 0000-0003-0289-0177

Akira Genseki

Akira Genseki, Technician at Open Facility Center, Tokyo Institute of Technology. Material evaluation with use of TEM, TOF-SIMS, SPM equipments. Orcid ID: 0000-0002-0845-4758

Tomohiro Hatano

Tomohiro Hatano, JEOL Tokyo, Japan. PhD candidate at Tokyo University of Agriculture and Technology. Biomaterial analysis with use of scanning electron microscopy.

Bolormaa Oyuntsetseg

Bolormaa Oyuntsetseg, Professor at Dept. of Chemistry, National University of Mongolia. Analytical chemistry, environmental chemistry. Orcid ID: 0000-0002-2861-7841

Kazuhiko Narisawa

Kazuhiko Narisawa, Professor at College of Agriculture, Ibaraki University, Japan. Microbial ecology, symbiotic mechanism between plant and Dark-Septate-Endophytes. Orcid ID: 0000-0003-2947-6523

Makiko Watanabe

Makiko Watanabe, Professor Emeritus at Tokyo Metropolitan University. Soil science, environmental science. Orcid ID: 0000-0001-7174-9439