Nano-fumed silica as a novel pollutant that inhibits the algicidal effect of p-hydroxybenzoic acid on Microcystis aeruginosa

ABSTRACT

Nanomaterials and/or contaminants are becoming more common in the developing world, but their effects on interspecific interactions are rarely reported, particularly in aquatic ecosystems. Thus, the present study determined the effects of the novel pollutant nano-fumed silica (NFS) on algal control by a macrophyte via the allelochemical p-hydroxybenzoic acid in a microcosm test. The allelochemical p-hydroxybenzoic acid caused significant decreases in chlorophyll a, but increased the amount of superoxide anion radicals (${\text{O}}_2^{\bullet -}$) and the electric conductivity in Microcystis aeruginosa. The 50% inhibitory concentration (IC₅₀) for p-hydroxybenzoic acid was 0.919 mmol/L in microalga during the exponential phase. Interestingly, NFS at 100–1600 mg/L had clear stimulatory effects on M. aeruginosa. When NFS at 800 mg/L was combined with different concentrations of p-hydroxybenzoic acid, the IC₅₀ for p-hydroxybenzoic acid was 1.045 mmol/L. Thus, NFS significantly reduced the algicidal effect exhibited by p-hydroxybenzoic acid on M. aeruginosa. Furthermore, NFS might act as a silicon nutrient and enhance allelopathic resistance in M. aeruginosa to inhibit the algicidal effects of macrophytes via allelopathy. These findings suggest that before algal control is considered using macrophyte allelopathy, it is essential to remove the pollutant NFS from polluted lakes.

KEYWORDS:

• Algicidal activity
• Microcystis aeruginosa
• nano-fumed silica
• p-hydroxybenzoic acid
• pollutant

Acknowledgements

We thank Prof. Boqiang Qin, Lei Fei, Dr Xiangming Tang, Dr Shiming Ding, Jianming Deng, and Dr Guangwei Zhu for their assistance with the experiments. We also thank Dr Duncan E. Jackson, the managing editors, and the reviewers for improving the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Shengpeng Zuo http://orcid.org/0000-0001-5448-0992

Additional information

Funding

This study was supported by National Key Research and Development Program of China [2017YFC0405205], Key Projects of The Outstanding Young Talents in Colleges and Universities of Anhui Province [gxyqZD2016024] and Anhui Provincial Natural Science Foundation of Anhui Province [1708085MC59].