title: Management of a toxic cyanobacterium bloom (Planktothrix rubescens) affecting an Italian drinking water basin: a case study.
abstract: An extraordinary bloom of Planktothrix rubescens, which can produce microcystins (MCs), was observed in early 2009 in the Occhito basin, used even as a source of drinking water in Southern Italy. Several activities, coordinated by a task force, were implemented to assess and manage the risk associated to drinking water contaminated by cyanobacteria. Main actions were: evaluation of analytical protocols for screening and confirmatory purpose, monitoring the drinking water supply chain, training of operators, a dedicated web site for risk communication. ELISA assay was considered suitable for health authorities as screening method for MCs and to optimize frequency of sampling according to alert levels, and as internal control for the water supplier. A liquid chromatography-tandem mass spectrometric method able to quantify 9 MCs was optimized with the aim of supporting health authorities in a comprehensive risk evaluation based on the relative toxicity of different congeners. Short, medium, and long-term corrective actions were implemented to mitigate the health risk. Preoxidation with chlorine dioxide followed by flocculation and settling have been shown to be effective in removing MCs in the water treatment plant. Over two years, despite the high levels of cyanobacteria (up to 160 × 10(6) cells/L) and MCs (28.4 μg/L) initially reached in surface waters, the drinking water distribution was never limited.
authors.affiliation: Department of Chemistry, University of Padua, Via Marzolo 1, 35131 Padova, Italy.
authors.forename: Sara
authors.initials: S
authors.lastname: Bogialli
authors.forename: Federica
authors.initials: F
authors.lastname: Nigro di Gregorio
authors.forename: Luca
authors.initials: L
authors.lastname: Lucentini
authors.forename: Emanuele
authors.initials: E
authors.lastname: Ferretti
authors.forename: Massimo
authors.initials: M
authors.lastname: Ottaviani
authors.forename: Nicola
authors.initials: N
authors.lastname: Ungaro
authors.forename: Pier Paolo
authors.initials: PP
authors.lastname: Abis
authors.forename: Matteo
authors.initials: M
authors.lastname: Cannarozzi de Grazia
mesh_terms: D000470:Alkaloids; D001427:Bacterial Toxins / Q000032:analysis*; D017606:Chlorine Compounds / Q000737:chemistry; D000458:Cyanobacteria / Q000302:isolation & purification*; D000087522:Cyanobacteria Toxins; D004203:Disinfection / Q000379:methods; D060766:Drinking Water / Q000032:analysis* / Q000382:microbiology; D004784:Environmental Monitoring; D005068:Eutrophication; D005427:Flocculation; D007558:Italy; D052998:Microcystins / Q000032:analysis; D010087:Oxides / Q000737:chemistry; D018570:Risk Assessment; D014326:Tropanes / Q000032:analysis; D014498:Uracil / Q000031:analogs & derivatives / Q000032:analysis; D014873:Water Pollutants / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods; D014881:Water Supply / Q000032:analysis
chemical_list: D000470:Alkaloids; D001427:Bacterial Toxins; D017606:Chlorine Compounds; D000087522:Cyanobacteria Toxins; D060766:Drinking Water; D052998:Microcystins; D010087:Oxides; D014326:Tropanes; D014873:Water Pollutants; C042133:chlorosyl; C089595:cylindrospermopsin; D014498:Uracil; C509783:anatoxin a; C025109:chlorine dioxide