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ARS Home » Pacific West Area » Parlier, California » San Joaquin Valley Agricultural Sciences Center » Water Management Research » Research » Publications at this Location » Publication #314989
Title: Sterilization effect of 254 nm UV-C irradiation against cynaobacteria Microcystis aeruginosa

Author
item ZHU, MEI - Anhui Agricultural University
item ZHANG, JUN - Chinese Academy Of Sciences
item YOU, QINGLIANG - Anhui Agricultural University
item Banuelos, Gary
item YU, ZENGLIANG - Chinese Academy Of Sciences
item LI, MIAO - Chinese Academy Of Sciences

Submitted to: Journal of Food Agriculture and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/25/2015
Publication Date: 4/20/2015
Citation: Zhu, M., Zhang, J., You, Q., Banuelos, G.S., Yu, Z., Li, M. 2015. Sterilization effect of 254 nm UV-C irradiation against cynaobacteria Microcystis aeruginosa. Journal of Food Agriculture and Environment. 13(1):43-47.

Interpretive Summary: Toxic blue-green algae water blooms are a significant threat to aquatic ecosystems in lakes, reservoirs, rivers, and estuaries and human health in many lake areas in China. Cyanobacterial blooms may cause clogging and produce undesirable odors and tastes. They are also responsible for the formation of some disinfection-by-products, and the generation of algal toxins. Therefore, the prevention and control of cyanobacteria blooms in lakes, reservoirs, rivers, and coastal waters has received wide-ranging attention around the world. The most effective way to control algal blooms is to reduce nutrient load into lakes, reservoirs, rivers, and estuaries. However, because of significant internal loading in these water bodies, especially from bottom sediment, control of external nutrient-load alone is not sufficient to prevent seasonal blue-green algae water blooms. Although various methods are currently being used to control harmful algal blooms, many of these techniques are of limited use. UV irradiation may represent a new technique for algae control. Irradiation has the advantage that there is no need to add any harmful chemical substances to the water, and it is economical and convenient. In this study, the sterilization effect on algae was observed under three different light intensities by UV-C irradiation. After 2 hours irradiation, cell densities under varied light intensities (low to high) dropped to about 60% to 80% percent of the control density, respectively. Due to severe damages to the cells, none of the cyanobacteria survived in the blue-green algae solutions after exposure to 20 hours irradiation. If UV-C radiation led to the production of H2O2 in the water solution, the production of the H2O2 may have controlled the algal growth. The use of UV irradiation could provide an attractive and inexpensive option for controlling algal growth in eutrophic lakes, reservoirs, and in rivers.

Technical Abstract: Harmful algal bloom (HAB) produced by several cyanobacterial species is a significant threat to many aquatic ecosystems around the world. Recently frequent occurrence of serious algal bloom in Lake Taihu, Lake Dianchi, and Lake Chaohu has become a serious concern in China. Although various methods are currently being used to control toxic blue-green algal water blooms, many of these techniques are of limited use. In this study, the use of 254 nm UV-C radiation to control algal growth was evaluated using the blue-green algae (Microcystis aeruginosa) as test species. The UV-C irradiation of more than 99 µW cm-2 light intensity was found to be lethal to M. aeruginosa. Noticeably, there were flat stages similar to the “saddle shape” curve in cells under 8 hours to 12 hours irradiation at various light intensities. This observation infers that the algae may have the anti-irradiation features under the UV-C irradiation analogously to other organisms’ appearances in radiation biology. Under incubated conditions, 20 hours exposure at 1370 µW cm-2 almost destroyed all the cells, whereas the unirradiated cells remained in suspension. We also observed that the UV-C radiation had a significant kill and wound effect on algal cells and controlled algal growth in ultrastructure slice-ups. Most algae cells dispersed with a UV-C dose of 7.2 J cm-2, whereas the unirradiated cells remained agglomerative. In conclusion, using equipment with UV-C lamps as an alternative to chemical algaecide, may be an economical and convenient method to control algal bloom and algal growth in some eutrophic water bodies.