title: An evaluation of the residual toxicity and chemistry of a sodium hydroxide-based ballast water treatment system for freshwater ships.
abstract: Nonnative organisms in the ballast water of freshwater ships must be killed to prevent the spread of invasive species. The ideal ballast water treatment system (BWTS) would kill 100% of ballast water organisms with minimal residual toxicity to organisms in receiving waters. In the present study, the residual toxicity and chemistry of a BWTS was evaluated. Sodium hydroxide was added to elevate pH to >11.5 to kill ballast water organisms, then reduced to pH <9 by sparging with wet-scrubbed diesel exhaust (the source of CO2 ). Cladocerans (Ceriodaphnia dubia), amphipods (Hyalella azteca), and fathead minnows (Pimephales promelas) were exposed for 2 d to BWTS water under an air atmosphere (pH drifted to ≥9) or a 2.5% CO2 atmosphere (pH 7.5-8.2), then transferred to control water for 5 d to assess potential delayed toxicity. Chemical concentrations in the BWTS water met vessel discharge guidelines with the exception of concentrations of copper. There was little to no residual toxicity to cladocerans or fish, but the BWTS water was toxic to amphipods. Maintaining a neutral pH and diluting BWTS water by 50% eliminated toxicity to the amphipods. The toxicity of BWTS water would likely be minimal because of rapid dilution in the receiving water, with subsurface release likely preventing pH rise. This BWTS has the potential to become a viable method for treating ballast water released into freshwater systems.
authors.affiliation: Maine Field Office, University of Maine, US Geological Survey, Orono, Maine.
authors.forename: Adria A
authors.initials: AA
authors.lastname: Elskus
authors.affiliation: Columbia Environmental Research Center, US Geological Survey, Columbia, Missouri.
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Ingersoll
authors.affiliation: Columbia Environmental Research Center, US Geological Survey, Columbia, Missouri.
authors.forename: Nile E
authors.initials: NE
authors.lastname: Kemble
authors.affiliation: Columbia Environmental Research Center, US Geological Survey, Columbia, Missouri.
authors.forename: Kathy R
authors.initials: KR
authors.lastname: Echols
authors.affiliation: Columbia Environmental Research Center, US Geological Survey, Columbia, Missouri.
authors.forename: William G
authors.initials: WG
authors.lastname: Brumbaugh
authors.affiliation: Henquinet Consulting, Houghton, Michigan, USA.
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Henquinet
authors.affiliation: S.O. Conte Anadromous Fish Research Laboratory, US Geological Survey, Turners Falls, Massachusetts.
authors.forename: Barnaby J
authors.initials: BJ
authors.lastname: Watten
mesh_terms: D033304:Amphipoda / Q000187:drug effects / Q000254:growth & development; D000818:Animals; D059001:Aquatic Organisms / Q000187:drug effects* / Q000254:growth & development; D002245:Carbon Dioxide / Q000737:chemistry; D033361:Cladocera / Q000187:drug effects / Q000254:growth & development; D003530:Cyprinidae / Q000254:growth & development; D005399:Fishes / Q000254:growth & development; D005618:Fresh Water / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D058865:Introduced Species; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis; D012767:Ships; D017693:Sodium Bicarbonate / Q000633:toxicity; D012972:Sodium Hydroxide / Q000633:toxicity*; D018675:Toxicity Tests; D018508:Water Purification; D060753:Water Quality
chemical_list: D011084:Polycyclic Aromatic Hydrocarbons; D002245:Carbon Dioxide; D012972:Sodium Hydroxide; D017693:Sodium Bicarbonate
keywords: Aquatic toxicology; Ballast discharge permit; Hyalella azteca; Invasive species; Water quality