Elimination of cyanobacteria and microcystins in irrigation water—effects of hydrogen peroxide treatment

Abstract

Cyanobacterial blooms pose a risk to wild and domestic animals as well as humans due to the toxins they may produce. Humans may be subjected to cyanobacterial toxins through many routes, e.g., by consuming contaminated drinking water, fish, and crop plants or through recreational activities. In earlier studies, cyanobacterial cells have been shown to accumulate on leafy plants after spray irrigation with cyanobacteria-containing water, and microcystin (MC) has been detected in the plant root system after irrigation with MC-containing water. This paper reports a series of experiments where lysis of cyanobacteria in abstracted lake water was induced by the use of hydrogen peroxide and the fate of released MCs was followed. The hydrogen peroxide-treated water was then used for spray irrigation of cultivated spinach and possible toxin accumulation in the plants was monitored. The water abstracted from Lake Köyliönjärvi, SW Finland, contained fairly low concentrations of intracellular MC prior to the hydrogen peroxide treatment (0.04 μg L −1 in July to 2.4 μg L −1 in September 2014). Hydrogen peroxide at sufficient doses was able to lyse cyanobacteria efficiently but released MCs were still present even after the application of the highest hydrogen peroxide dose of 20 mg L −1. No traces of MC were detected in the spinach leaves. The viability of moving phytoplankton and zooplankton was also monitored after the application of hydrogen peroxide. Hydrogen peroxide at 10 mg L −1 or higher had a detrimental effect on the moving phytoplankton and zooplankton.

Algal Toxic Compounds and Their Aeroterrestrial, Airborne and other Extremophilic Producers with Attention to Soil and Plant Contamination: A Review

“…Although constantly increasing, the number of experiments is limited with exceptional work in natural conditions, and few studies addressed the plants susceptibility to phycotoxins at environmentally relevant concentrations [ 225 , 226 , 228 ]. Despite some crop plants and some aquatic macrophytes (e.g., Ceratophyllum demersum , Elodea canadensis , Phragmites australis , Vesicularia dubyana , and Azolla filiculoides ) having demonstrated possibilities for self-decontamination, for development of tolerance or resistance to cyanotoxins and even registered better growth at certain MC or CYN concentrations, there is a general consensus on the strong negative economic impact with health risk hazards of toxin-containing water, applied as standard or spray irrigation [ 227 , 228 , 229 , 230 , 231 , 232 , 233 , 234 , 235 , 236 , 237 , 238 , 239 , 240 ]. Moreover, after conventional treatment, water still can contain extracellular phycotoxins (e.g., MCs), released after lysis of cells [ 236 ].…”

“…Despite some crop plants and some aquatic macrophytes (e.g., Ceratophyllum demersum , Elodea canadensis , Phragmites australis , Vesicularia dubyana , and Azolla filiculoides ) having demonstrated possibilities for self-decontamination, for development of tolerance or resistance to cyanotoxins and even registered better growth at certain MC or CYN concentrations, there is a general consensus on the strong negative economic impact with health risk hazards of toxin-containing water, applied as standard or spray irrigation [ 227 , 228 , 229 , 230 , 231 , 232 , 233 , 234 , 235 , 236 , 237 , 238 , 239 , 240 ]. Moreover, after conventional treatment, water still can contain extracellular phycotoxins (e.g., MCs), released after lysis of cells [ 236 ]. All studies showed that aquatic macrophytes absorb through all submerged parts [ 229 , 231 ], and crop plants irrigated by infested water can absorb phycotoxins through roots or accumulate it on leaves, and that the effects can be harmful for humans even in cases of no visible changes [ 115 , 225 , 241 ].…”

“…For example, cyanotoxins can affect the plants metabolism, which can lead to the accumulation of potential allergenic proteins [ 242 ]. Therefore, the consumption of contaminated vegetables and food supplements became recognized as additional important exposure route [ 228 , 236 , 243 ].…”

“…According to the accumulated knowledge, such infested water may impair the photosynthesis, inflict severe oxidative stress, affect mineral accumulation by plants, provoke adverse histological modifications in primary plant tissues, reduce the germination rate of seeds, inhibit the growth and development of seedlings, cause alteration of the quality and the productivity of crop plants with a potential to move these toxins into farm animals and thus have detrimental impact in the whole food chain [ 115 , 217 , 223 , 226 , 227 , 228 , 236 , 244 , 245 , 246 ]. The reported effects on metabolic processes and related germination and growth rates depend both on the toxin variant used and on the detoxication enzymatic activity of tested plants, such as Azolla filiculoides , Anethum graveolens , Brassica napus , Brassica cretica (Syn.…”

Ameliorative effects of jamun seed and orange peel extracts on microcystin LR induced alterations in calcitonin cells and parathyroid gland of rats

“…These cyanobacteria produce and release a large variety of biologically active secondary metabolites, cyanotoxins (Carmichael, 2001; Zhou, Tu, & Xu, 2015). Microcystins are an environmentally abundant large group of cyclic heptapeptide hepatotoxins (Brózman, Kubickova, & Pavel Babica Petra, 2020; Spoof et al, 2020). there are about 250 microcystin congeners varying primarily in amino acid constitution and degree of methylation (Spoof & Catherine, 2017) among which microcystin LR is widely studied variant (Brózman et al, 2020).…”