Microcystin-LR (MC-LR), an algal toxin (cyanotoxin) common in sources of drinking water, poses a major human health hazard due to its high toxicity. In this study, UV/chlorine was evaluated as a potentially practical and effective process for the degradation of MC-LR. Via mass spectrometry analysis, fewer chlorinated-MC-LR products were detected with UV/chlorine treatment than with chlorination, and a transformation pathway for MC-LR by UV/chlorine was proposed. Different degrees of rapid degradation of MC-LR were observed with varying pH (6-10.4), oxidant dosage (0.5-3 mg L), natural organic matter (0-7 mg L), and natural water sources. In contrast to the formation of primarily chloroform and dichloroacetic acid in deionized water where MC-LR serves as the only carbon source, additional chlorinated disinfection byproducts were produced when sand filtered natural water was used as a background matrix. The UV/chlorine treated samples also showed quantitatively less cytotoxicity in vitro in HepaRG human liver cell line tests than chlorination treated samples. Following 16 min (96 mJ cm) of UV irradiation combined with 1.5 mg L chlorine treatment, the cell viability of the samples increased from 80% after exposure to 1 mg L MC-LR to 90%, while chlorination treatment evidenced no reduction in cytotoxicity with the same reaction time.

Harmful algal blooms (HABs) and their toxins are a significant and continuing threat to aquatic life in freshwater, estuarine, and coastal water ecosystems. Scientific understanding of the impacts of HABs on aquatic ecosystems has been hampered, in part, by limitations in the methodologies to measure cyanotoxins in complex matrices. This literature review discusses the methodologies currently used to measure the most commonly found freshwater cyanotoxins and prymnesins in various matrices and to assess their advantages and limitations. Identifying and quantifying cyanotoxins in surface waters, fish tissue, organs, and other matrices are crucial for risk assessment and for ensuring quality of food and water for consumption and recreational uses. This paper also summarizes currently available tissue extraction, preparation, and detection methods mentioned in previous studies that have quantified toxins in complex matrices. The structural diversity and complexity of many cyanobacterial and algal metabolites further impede accurate quantitation and structural confirmation for various cyanotoxins. Liquid chromatography–triple quadrupole mass spectrometer (LC–MS/MS) to enhance the sensitivity and selectivity of toxin analysis has become an essential tool for cyanotoxin detection and can potentially be used for the concurrent analysis of multiple toxins.

No abstract

Bench-scale trials were performed to (1) expose Microcystis aeruginosa cells to potassium permanganate (KMnO 4 ) doses of 1, 3, and 5 mg/L at contact times (CTs) of 15, 30, and 90 min, pH levels of 7 and 9, and turbidities of 0.1, 5, and 20 ntu, respectively;(2) compare the impacts of oxidation alone and oxidation plus powdered activated carbon (PAC) for the final 60 min of CT; and (3) evaluate the impact of these treatment conditions on extracellular microcystins (MCs), extra-plus intracellular (combined) MCs, cell membrane integrity, and chlorophyll a concentrations. Toxin releases from the cells were observed at both pH levels. The greatest toxin releases were observed at the lowest KMnO 4 doses. The toxin releases were accompanied by relatively stable total cell counts, increases in membrane-compromised cells, and decreases in chlorophyll a. The application of 10 mg/L PAC resulted in extracellular toxin concentrations that were markedly lower than those observed in oxidant-only situations.

To assess the practical implications of various bottle materials used in anion exchange (IX) or granular activated carbon (GAC) isotherm experiments, adsorption of seven per-and polyfluoroalkyl substances (PFAS) onto three common bottle materials (silanized glass, polypropylene, and high-density polyethylene [HDPE]) were screened. Results were similar between bottle materials; therefore,