title: Effect of arsenic and mercury speciation on inhibition of respiration rate in activated sludge systems.
abstract: The inhibition effect of arsenite, As(III), arsenate, As(V), inorganic mercury, Hg(II) and methylmercury, MeHg, on the respiration rate of activated heterotrophic sludge microorganisms was evaluated. As(III) and MeHg were much more toxic to activated sludge than As(V) and Hg(II) respectively. The effect of various experimental parameters on the toxicity, such as sludge age, concentration of suspended solids and exposure time, was investigated. An increase of sludge age or the concentration of suspended solids reduces the observed inhibition. Longer exposure seems to dramatically increase the inhibition of As(III), MeHg and Hg(II) during the first hours of exposure, while the later inhibition increases at a slower rate. On the contrary, in the presence of As(V), 24 hours after exposure, the respiration rate was similar to that of the control biomass.
authors.affiliation: Laboratory of Water and Air Quality, Department of Environmental Studies, University of the Aegean, Theofrastou and Alkaiou Str., 81100 Mytilene, Greece.
authors.forename: Athanasios S
authors.initials: AS
authors.lastname: Stasinakis
authors.forename: Nikolaos S
authors.initials: NS
authors.lastname: Thomaidis
authors.forename: Apostolos S
authors.initials: AS
authors.lastname: Giannes
authors.forename: Themistokles D
authors.initials: TD
authors.lastname: Lekkas
mesh_terms: D001151:Arsenic / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects* / Q000378:metabolism; D018533:Biomass; D006801:Humans; D007477:Ions; D008628:Mercury / Q000494:pharmacology*; D008767:Methylmercury Compounds / Q000494:pharmacology*; D012119:Respiration; D012722:Sewage / Q000382:microbiology*; D012988:Soil Microbiology
chemical_list: D007477:Ions; D008767:Methylmercury Compounds; D012722:Sewage; D008628:Mercury; D001151:Arsenic