Impact of eutrophication on arsenic cycling in freshwaters. (1st March 2019)

• Record Type: Journal Article
• Authors: Tang, Ying; Zhang, Meiyi; Sun, Guoxin; Pan, Gang
• Is Part Of: Water research. Volume 150(2019)
• Page Start: 191
• Page End: 199
• Publication Date: 2019-03-01
• Subjects: Harmful algae bloom -- Arsenic volatilization -- Organic matter -- Arsenic metabolism functional genes -- Sediment-water-air interfaces -- X-ray absorption spectroscopy; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2018.11.046
• Languages: English
• ISSNs: 0043-1354

Abstract

Abstract: Many arsenic-bearing freshwaters are facing with eutrophication and consequent algae-induced anoxia/hypoxia events. However, arsenic cycling in eutrophic waters and its impact on public health are poorly understood. Laboratory simulation experiments are performed in this study to investigate the effect of algal blooms on the cycling of arsenic in a sediment–water–air system. We found that the anoxia induced by the degradation of algal biomass promoted an acute arsenic (mostly As(III)) release within two days from sediment to both the water and atmosphere, and the release effluxes were proportional to the algae dosage. The reduction and methylation of arsenic were enhanced at the sediment–water interface, owing to the significant increase in arsenate reductase genes ( arr A and ars C), and arsenite methyltransferase genes ( ars M) caused by increased anoxia. The analysis of synchrotron-based X-ray absorption spectroscopy indicated that the concomitantly released natural organic matter (NOM) and sulfur (S) at the sediment–water interface reduced the As(III) release to a certain extent in the later reducing period of incubation, by forming As2 S3 (43–51%) and As(III)-Fe-NOM (28–35%). Our results highlight the needs for the in-situ assessment of volatile arsenic in eutrophic freshwaters with its risk to human and animal health. Graphical abstract: Highlights: Algal blooms degradation increases arsenic toxic impact to public health. Organic matter is a sequestrator of arsenic in anoxic sediments. Hypoxia/anoxia induced microbial changes contribute to arsenic speciation. Volatile arsenic in algal water-sediment systems is assessed i n-situ.