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We exposed water samples from a recreational lake dominated by the cyanobacterium Planktothrix agardhii to different concentrations of hydrogen peroxide (H2O2). An addition of 0.33 mg·L-1 of H2O2 was the lowest effective dose for the decay of chlorophyll-a concentration to half of the original in 14 h with light and 17 h in experiments without light. With 3.33 mg·L-1 of H2O2, the values of the chemical oxygen demand (COD) decreased to half at 36 and 126 h in experiments performed with and without light, respectively. With increasing H2O2, there is a decrease in the total and faecal coliform, and this effect was made more pronounced by light. Total and faecal coliform were inhibited completely 48 h after addition of 3.33 mg·L-1 H2O2. Although the densities of cyanobacterial cells exposed to H2O2 did not decrease, transmission electron microscope observation of the trichomes showed several stages of degeneration, and the cells were collapsed after 48 h of 3.33 mg·L-1 of H2O2 addition in the presence of light. Our results demonstrate that H2O2 could be potentially used in hypertrophic systems because it not only collapses cyanobacterial cells and coliform bacteria but may also reduce chlorophyll-a content and chemical oxygen demand.

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Cyanobacterial blooms and hepatotoxic microcystins (MCs) usually occur in summer, constituting a sanitary and environmental problem in Salto Grande Dam, Argentina. Water sports and recreational activities take place in summer in this lake. We reported an acute case of cyanobacterial poisoning in Salto Grande dam, Argentina, which occurred in January 2007. Accidentally, a young man was immersed in an intense bloom of Microcystis spp. A level of 48.6 µg·L(-1) of microcystin-LR was detected in water samples. Four hours after exposure, the patient showed nausea, abdominal pain and fever. Three days later, dyspnea and respiratory distress were reported. The patient was hospitalized in intensive care and diagnosed with an atypical pneumonia. Finally, a week after the exposure, the patient developed a hepatotoxicosis with a significant increase of hepatic damage biomarkers (ALT, AST and γGT). Complete recovery took place within 20 days. This is the first study to show an acute intoxication with microcystin-producing cyanobacteria blooms in recreational water.

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This paper is the first report on microcystins producer blooms of Microcystis aeruginosa in the Argentinean coast of the R¨ªo de la Plata river, the most important drinkingwater supply of Argentina. The distribution of toxic cyanobacterium Microcystis cf. aeruginosa blooms in the Argentinean coast of the Rio de la Plata river was studied from December 2003 and January 2006. Microcystis aeruginosa persisted in the river with values ranged between 0 -7.8 104 cells ml-1. Samples of two Microcystis aeruginosa water blooms were collected at La Plata river and were analyzed by the mouse bioassay and by high-performance liquid chromatography with Diode-array and MS detector. The samples showed high hepatotoxicityin mouse bioassay and, in accordance, important amount of microcystins. The bloom samples contained microcystins LR and a variant of microcystin with a molecular ion [M+H]+= 1037.8 m/z as major components. The total toxin content found in these samples was 0.94¦Ìg/mg and 0.69¦Ìg/mg of lyophilised cells. We conclude that the presence of toxic clones of Microcystisaeruginosa in the Argentinean coast of the Rio de la Plata is an actual sanitary and environmental problem and that further studies are necessary to make the risk assessment.

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In April 2000, alterations in drinking water quality, such as turbidity and odors similar to those of organochloride pesticides, were detected at Bahía Blanca (Argentina). This fact was associated to reports of dermic reactions and respiratory problems in the population. Samples drawn from Paso de las Piedras reservoir, two water treatment plants of at inlet and outlet points and at several particular houses were analyzed. Total phytoplankton in the reservoir varied between 49440 and 84832 cells.ml-1, while dominant species was, Anabaena circinalis. Efficiency to remove microorganisms (ER) by the treatment plants considering cell number of total phytoplankton was analyzed. Bacteriological analysis, qualitative and quantitative studies of phytoplankton, pesticides, THM (trihalomethanes) and BTEX (benzene, toluene, ethylbenzene and xylene) analysis were carried out in samples of domestic supply and in the treatment plants. Even though samples were bacteriological potable, Anabaena circinalis and Microcystis aeruginosa algae were found at high concentrations in some cases. No pesticides were detected. THM and BTEX were below guideline values into recommendations for drinking water. Geosmin was responsible for detected odors. Besides, Copaene, another volatile metabolite, which on account in its structure could be considered a Geosmin precursor, was also detected. In Argentina, this was the first report of Cyanobacteria presence in drinking water.

En abril de 2000, en Bahía Blanca (Argentina), se detectaron alteraciones en el agua de bebida, turbidez y olor semejante a "Gamexane". Esto coincidió con la aparición de problemas dérmicos y respiratorios en la población. Para determinar el origen del problema, se analizaron muestras, tomadas en el embalse Paso de las Piedras, en las plantas potabilizadoras y en varios domicilios particulares. En el embalse, la densidad celular del fitoplancton, fluctuó entre 49440 y 84832 cél/ml-1, muy por encima de los valores de referencia. Anabaena circinalis en altas concentraciones fue la especie dominante (48320 - 84032 células por mililitro). Se cuantificó la eficiencia de las plantas de tratamiento (algas-entrada/algas-salida). Anabaena circinalis y Microcystis aeruginosa fueron encontradas a la entrada y a la salida de las plantas, indicando una baja eficiencia de las plantas de tratamiento. Para el agua domiciliaria, se realizaron estudios fitoplanctonicos; análisis bacteriológicos; presencia de plaguicidas, trihalometanos y BTEX. Si bien, bacteriológicamente el agua era potable, se encontraron Cyanobacteria en algunos casos en concentraciones muy altas. La presencia de pesticidas resultó negativa. La media de los THM y de los valores de BTEX resultaron menores a valores guías para agua potable. Se detectó la presencia de Geosmina, resultando el responsable del fuerte olor. Asimismo, se halló otro metabolito volátil, Copaene, que por su estructura pudiera llegar a considerarse precursor de la Geosmina. Este es el primer reporte de la presencia de cianobacterias en aguas de consumo humano en Argentina.

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Las algas verdes-azuladas, Cyanophyta o cianobacteria, son un grupo de organismos muy hetereogéneo. Algunas de ellas, bajo cxondiciones ambientales determinadas, son capaces de producir tanto metabolitos volátiles como toxinas, que liberadas al ambiente, suelen producir trastornos de importancis económica y sanitaria. En este trabajo se presenta una revisión rerferida al desarrollo de cyanophyta en ecosistemas acuáticos continentales en relación con la modificación de los caracteres organolépticos del ambiente. Se detallan los factores ambientales que favorecen el desarrollo de floraciones.Asimismo, se dan a conocer las características de las toxinas (neurotoxinas, hepatoxinas y dermatoxinas) que esta algas son capaces de producir. Los metabolitos volatiles y lñas cianotoxinas representan un serio riesgo, tanto para la salud humana como animal. Por otra parte, se describe la sintomatología correspondiente en cada cianotoxina, las estructuras químicas identificadas y los métodos biológicos análiticos, necesarios para realñizar determinaciones cualitativas y cuantitativas de las cianotoxinas.

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Las algas verdes-azuladas, Cyanophyta o cianobacteria, son un grupo de organismos muy hetereogéneo. Algunas de ellas, bajo cxondiciones ambientales determinadas, son capaces de producir tanto metabolitos volátiles como toxinas, que liberadas al ambiente, suelen producir trastornos de importancis económica y sanitaria. En este trabajo se presenta una revisión rerferida al desarrollo de cyanophyta en ecosistemas acuáticos continentales en relación con la modificación de los caracteres organolépticos del ambiente. Se detallan los factores ambientales que favorecen el desarrollo de floraciones.Asimismo, se dan a conocer las características de las toxinas (neurotoxinas, hepatoxinas y dermatoxinas) que esta algas son capaces de producir. Los metabolitos volatiles y lñas cianotoxinas representan un serio riesgo, tanto para la salud humana como animal. Por otra parte, se describe la sintomatología correspondiente en cada cianotoxina, las estructuras químicas identificadas y los métodos biológicos análiticos, necesarios para realñizar determinaciones cualitativas y cuantitativas de las cianotoxinas. (AU)

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