Degradation mechanisms of cyanobacteria neurotoxin β-N-methylamino-l-alanine (BMAA) during UV254/H2O2 process: Kinetics and pathways

Boyin Yan; Songxue Wang; Zhiquan Liu; Da Wang; Wenxin Shi; Fuyi Cui

doi:10.1016/j.chemosphere.2022.134939

Degradation mechanisms of cyanobacteria neurotoxin β-N-methylamino-l-alanine (BMAA) during UV₂₅₄/H₂O₂ process: Kinetics and pathways

Chemosphere. 2022 Sep:302:134939. doi: 10.1016/j.chemosphere.2022.134939. Epub 2022 May 11.

Authors

Boyin Yan¹, Songxue Wang¹, Zhiquan Liu², Da Wang³, Wenxin Shi⁴, Fuyi Cui⁴

Affiliations

¹ College of Environmental and Municipal Engineering, Qingdao University of Technology, Qingdao, 266033, China.
² Institute of Environmental Research at Greater Bay, Key Laboratory by Water Quality and Conservation of the Pearl River Delta, Ministry of Education, Guangzhou University, Guangzhou, 510006, China. Electronic address: zhiquanliu@gzhu.edu.cn.
³ Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of an Environment, Zhejiang University of Technology, Hangzhou, 310032, China.
⁴ School of Environment and Ecology, Chongqing University, Chongqing, 400044, China.

PMID: 35561764
DOI: 10.1016/j.chemosphere.2022.134939

Abstract

In this work, the UV₂₅₄/H₂O₂ process was utilized to remove β-N-methylamino-l-alanine (BMAA), a kind of cyanobacteria neurotoxin, and the influence of reaction parameters and environmental factors on the degradation of BMAA has been systematically investigated. The results showed that BMAA could be effectively removed in the UV₂₅₄/H₂O₂ system compared to UV or H₂O₂ alone and OH was confirmed as the main ROS to degrade BMAA. The degradation rate of BMAA increased first and then decreased with the increase of pH and the maximum k_obs was 0.1545 min^-1 obtained at pH 9. The removal of BMAA in the UV₂₅₄/H₂O₂ system was inhibited in actual water, while the degradation rate of BMAA in actual water could still exceed 90% by appropriately extending the reaction time. The decrease in the degradation efficiency of BMAA in actual water was primarily due to the ultraviolet light absorption and competition effects of NOM, and anions (Cl^- and HCO₃^-) would also inhibit the degradation of BMAA. Five by-products ([M - H]^- = 118, 103, 88, 87 and 59) were identified in this study and the degradation pathways of BMAA were proposed. The production of by-products was attributed to the fracture of the C-N bond and hydroxylation reaction. This study is worthwhile to deepen the understanding of the degradation mechanism of BMAA in the UV₂₅₄/H₂O₂ system.

Keywords: BMAA; By-products; Hydroxyl radical; Steady-state kinetics model; UV(254)/H(2)O(2).

MeSH terms

Amino Acids, Diamino* / metabolism
Cyanobacteria Toxins
Cyanobacteria* / metabolism
Hydrogen Peroxide / chemistry
Kinetics
Neurotoxins / metabolism
Ultraviolet Rays
Water / metabolism

Substances

Amino Acids, Diamino
Cyanobacteria Toxins
Neurotoxins
Water
beta-N-methylamino-L-alanine
Hydrogen Peroxide