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Global warming and eutrophication may lead to increased incidence of harmful algal blooms and related production of cyanotoxins that can be toxic to aquatic plants. Previous studies have evaluated the phytotoxic effects of cyanotoxins on aquatic plants. However, most studies have evaluated only a limited number of plant species and cyanotoxins; there is also considerable variability between studies, which obscures general patterns and hinders understanding of the phytotoxic effects of cyanotoxins. Here, we conducted a comprehensive meta-analysis by compiling 41 published papers to estimate the phytotoxic effects of anatoxin-a, cylindrospermopsin, and microcystins in 34 species of aquatic plants, with the aim of 1) investigating the phytotoxicity of different cyanotoxins to aquatic plants; 2) determining the aquatic plant species most sensitive to the phytotoxic effects of cyanotoxins; and 3) evaluating the bioaccumulation potential of cyanotoxins in aquatic plants. Most aquatic plants were negatively affected by cyanotoxin exposure and their response was dose-dependent; however, morphological indicators and photosynthesis of certain aquatic plants were marginally stimulated under low concentrations of anatoxin-a and cylindrospermopsin. Anatoxin-a showed the greatest bioaccumulation capacity in aquatic plants compared to cylindrospermopsin and microcystin variants. Bioaccumulation factors of cyanotoxins in aquatic plants generally decreased with increasing water exposure concentrations. Our study supports the One Health goal to manage the risk of public exposure to toxic substances, and indicates that cyanotoxins warrant further investigations in aquatic plants. Environmental managers and public health authorities need to be alert to the long-term exposure and chronic toxicity of cyanotoxins, and the potential trophic transfer of cyanotoxins from aquatic plants to higher-order organisms., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Harmful algal blooms of cyanobacteria (CyanoHABs) can lead to the release of potent toxins that can seriously affect ecosystem integrity. Some freshwater watersheds are particularly at risk considering the threats to already imperiled wildlife. The consumption of tainted drinking water and contaminated food also raises concerns for human health. In the present study, a pilot survey was conducted in the riverine ecosystem of the Pike River Ecological Reserve (QC, Canada) near Missisquoi Bay, Lake Champlain. We examined the occurrence of multiclass cyanotoxins including 12 microcystins, anatoxins, cylindrospermopsin (CYN), anabaenopeptins (AP-A, AP-B), and cyanopeptolin-A in surface waters and wild-caught fish during the summer 2018. Out of the 18 targeted cyanotoxins, 14 were detected in bloom-impacted surface water samples; toxins peaked during early-mid September with the highest concentrations for MC-LR (3.8 μg L -1 ) and MC-RR (2.9 μg L -1 ). Among the 71 field-collected fish from 10 species, 30% had positive detections to at least one cyanotoxin. In positive samples, concentration ranges in fish muscle were as follows for summed microcystins (∑MCs: 0.16-9.2 μg kg -1 ), CYN (46-75 μg kg -1 ), AP-A (1.1-5.4 μg kg -1 ), and AP-B (0.12-5.0 μg kg -1 ). To the best of our knowledge, this is one the first reports of anabaenopeptins occurrence in wildlife. The maximum ∑MCs in fish was 1.15-fold higher than the World Health Organization (WHO) daily intake recommendation for adults and nearly equated the derived value for young children. The concentration of CYN was also about 3-fold higher than the limit derived from the human health guideline values., (Copyright © 2021 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Sand as a filter media is often challenged by the presence of organics in the form of natural organic matter, metal ions, and various micropollutants in the source water. It is mainly due to the presence of limited active adsorption sites and low surface area that governs an ineffective adsorption potential of the sand material. Herein, graphitized sand was synthesized to tackle the above limitations using two sugar solution sources: a) brewery effluent (as a low-cost solution) (GS1) and; b) sucrose solution (GS2). GS1 showed 68%, 60%, and 99% higher maximum adsorption constant (q max ) for divalent metal ions: iron, copper, and manganese, respectively as compared to raw sand (RS). Coating of MnO 2 over the graphitized sand (GSMs: GS1M and GS2M) further helped in Microcystin-LR (MC-LR) removal (3%-9%) when inoculated with MC-LR-degraders, but was not as effective in removing metals, organic carbon and nitrogen when compared to just graphitized sand (GS1 or GS2). Inoculating GS and GSMs (for both sugar sources) not only helped in higher MC-LR removal (10%-15% more) but also enhanced the removal of other water contaminants including metals, organic nitrogen, and carbon. GS1 showed 20% and 50% more MC-LR removal than the sand material when tested at a low and high initial concentration of MC-LR (5 µg/L and 50 µg/L). The highest breakthrough period was obtained for GS1 filter using 1 mg/L Rhodamine-B dye, which was 12 times (48 min) more than the raw sand filter and almost 2.5 times (second best, 21 min) than GS1M. After three cycles of regeneration and reuse of GS1 filter, a decrease of just 14% in saturation adsorption capacity indicated its high reusability aspects., (Copyright © 2019 Elsevier B.V. All rights reserved.)

A fast and high-throughput method is proposed for the determination of total microcystins (ΣMC) in environmental surface waters. After a 1-h Lemieux-von Rudloff oxidation step to yield the 2-methyl-3-methoxy-4-phenylbutyric acid (MMPB) moiety, samples were quenched, filtered, and directly analyzed. This was achieved via solid phase extraction (SPE) coupled on-line to ultra-high performance liquid chromatography electrospray ionization triple stage quadrupole mass spectrometry. The choice of on-line SPE settings was conducted using experimental designs. Given the matrix complexity of oxidation extracts, the on-line desalting step was found to be a critical parameter to ensure suitable method robustness. The on-line sample loading volume was 5mL, and the wash volume applied for on-line desalting was 3mL. Instrumental analysis was performed in just 8min. The method limit of quantification was 0.5ngL -1 ΣMC (i.e. 2000 times lower than the current World Health Organization - WHO drinking water guideline). Excellent determination coefficients were observed for matrix-free and matrix-based calibration curves alike, and the linearity range tested spanned∼4 orders of magnitude. Accuracy and intermediate precision did not depend on the spike level and proved satisfactory (in the range of 93-110% and 3-6%, respectively). A thorough assessment of instrumental matrix effects was conducted by comparing standard additions curves in several lake and river oxidation extracts with the matrix-free reference. Regardless of the internal standard used (4-PB or D3-MMPB), instrumental matrix effects were efficiently compensated. The matrix effect that may occur at the earlier sample preparation stage was evaluated separately. While the oxidation step was generally not complete (yield ∼65%), the conversion rates of MCs into MMPB remained within a consistent range of values regardless of matrix type. No significant back-pressure was observed upon consecutive injections of oxidation-based samples, while the instrumental sensitivity remained unaffected. The herein described method could therefore be eligible for future large-scale monitoring surveys. The method was applied to a selection of surface water samples (n=30) collected across the province of Québec, Canada, and the results were compared to those achieved by an individual variant analysis of 8 MC congeners and a commercial ELISA kit., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Adsorption of mixtures of cyanotoxins onto sediment as a dominant mechanism in the elimination of cyanotoxins from the aqueous phase has not been extensively investigated. The aim of this study was to investigate adsorption and desorption behavior of six microcystins including microcystin (MC)-LR, RR, YR, LY, LW and LF and cylindrospermopsin (CYN) on natural sediment. Freundlich and Langmuir isotherms could be fitted for MC-LR, RR, YR and CYN. Sorption kinetics showed immediate rapid adsorption for all cyanotoxins: CYN, MCLW and MCLF were adsorbed 72.6%, 56.7% and 55.3% respectively within 2 h. Results of desorption experiments demonstrated that less than 9% of cyanotoxins desorbed from sediment within 96 h. Adsorption of cyanotoxins onto three fractionated sediments particles, clay-silt (<75 μm), find sand (75-315 μm) and coarse sand (315-2000 μm) demonstrated that adsorption capacity of coarse sand fraction for all the tested cyanotoxins was less than 4% of the clay-silt fraction. Results of this study revealed that there is a potential for cyanotoxins to accumulate in the sediments of lakes, as well as in drinking water treatment plants. Monitoring programs must consider cyanotoxins in the particulate phase to avoid largely underestimating toxin concentrations following their release from blooms., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Algal dietary supplements are marketed for their health benefits and nutritional value. However, these types of products can be contaminated by toxins produced by co-occurring toxigenic cyanobacteria. In order to evaluate the contamination of different supplements available on the North American market, we purchased 37 samples of spirulina, Aphanizomenon flos-aquae , Chlorella and kelp, and analysed them for 27 cyanotoxins using liquid chromatography mass spectrometry methods (HPLC-MS/MS and HPLC-HRMS). We found microcystins (MC) in the 8 Aphanizomenon samples with levels up to 1000 ng g−1 dw and 2,4-diaminobutyric acid (DAB) in all samples with values ranging from 3 to 1600 ng g−1. Anatoxin-a (ANA) and β-amino- N -methylalanine (BAMA) were not detected, while other toxins were detected with no clear link to the nature of the alga. Considering these results, Aphanizomenon products may require stricter monitoring to prevent further contamination. The findings are also of interest to consumers so that they can properly assess the risks that may be involved in the regular consumption of certain algal dietary supplements. • 27 cyanotoxins were analysed in algal dietary supplements by HPLC-MS methods. • All Aphanizomenon products were contaminated by microcystins. • The BMAA isomer DAB was detected in all products. • Two samples exceeded the equivalent dose derived from the EPA Drinking Water Health Advisories for adults for microcystins. [ABSTRACT FROM AUTHOR]

Cyanotoxins are associated with harmful cyanobacterial blooms, but also exist in biological soil crusts and soils irrigated with cyanobacteria-contaminated water. To achieve an accurate analysis of cyanotoxins in soil, effective extraction, purification and determination methods are imperative. The most challenging aspect is extracting cyanotoxins from soil, due to their tendency to bind strongly to the soil matrix. We used a methanol-ammonium acetate solution to efficiently extract 17 cyanotoxins (microcystins, cylindrospermopsin, anatoxins, anabaenopeptins and cyanopeptolin) from soil. The extract was purified by on-line solid-phase extraction coupled with ultra-high-performance liquid chromatography tandem mass spectrometry. The optimized procedure involved two ultrasonication cycles of 15 min with 4 mL of methanol + 200 mM ammonium acetate, which recovered 60% to >90% of the added cyanotoxins from five soils with diverse organic matter, pH and texture. The method improved extraction by up to 10 times compared to a methanol/water solution. Linearity, accuracy and precision were validated on matrix-mixed soil with surrogate microcystin and cylindrospermopsin internal standards. Limits of detection were 0.001–0.3 ng g−1, depending on the cyanotoxins. The method was used to analyze cyanotoxins in 25 field-collected soils from Quebec, Canada. Out of the 25 soil samples, 11 soils had at least one cyanotoxin, and up to 8 different cyanotoxins were detected in one soil. The sum of all microcystins congeners was from 0.02 to 31 ng microcystins g−1 soil. We also detected anabaenopeptin, the first reported occurrence of this cyanotoxin in soil. Image 1 • Method optimized to analyze multi-class cyanotoxins in soil. • Good recovery of microcystins and anatoxins was achieved (60–110%). • On-line purification coupled to LC-MS/MS yielded LODs between 0.001 and 0.3 ng g−1. • 44% of field soils had detectable cyanotoxins, with up to 30 ng microcystins g−1. • This study is the first to report anabaenopeptin in field-collected soils. [ABSTRACT FROM AUTHOR]

• Cyanotoxin storage stability in water was examined under different conditions. • CYN and anabaenopeptins sharply decreased within a few days when stored at 20 °C. • Long-term decrease (365 days) was reduced when samples were stored frozen. • Similar conclusions were reached for spiked and field-collected water samples. • Samples with tryptophan-containing microcystins should be analyzed expeditously. Reproducible analytical procedures and rigorous quality control are imperative for an accurate monitoring of cyanobacterial toxins in environmental water samples. In this study, the short-term and long-term storage stability of diverse cyanotoxins (anatoxins, cylindrospermopsin, anabaenopeptins, and 12 microcystins) was evaluated in water samples, under different scenarios. Transport controls were performed at three monitoring sites in spiked ultrapure water and lake water to investigate short-term stability issues. Medium-term storage stability was evaluated for up to 14–28 days in ultrapure water, chlorine-treated drinking water (amended with reductant), and surface water (filtered and unfiltered) stored at different temperatures (20 °C, 4 °C, and –20 °C). Substantial decreases of cylindrospermopsin and anabaenopeptins were observed in tap water (20 °C) and unfiltered surface water (20 °C or 4 °C). Regardless of matrix type, cyanotoxin recoveries generally remained within an 80–120% range when the water samples were kept frozen. After a prolonged storage duration of 365 days at –20 °C, most cyanotoxins experienced decreases in the range of 10–20%. The notable exception was for the tryptophan-containing MC-LW and MC-WR, with more substantial variations (30% to 50% decrease) and conversion to N-formylkynurenine analogs. Reanalysis of field-collected surface waters after long-term storage at –20 °C also indicated significantly decreasing trends of cyanotoxins (between 6% and 23% decrease). In view of the above, short sample hold times should be favored as recommended in EPA methods. [ABSTRACT FROM AUTHOR]