Publications (12)24.72 Total impact
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Article: Water chemistry matters in metal-toxicity papers.
Environmental Toxicology and Chemistry 04/2012; 31(4):689-90; author reply 690-2. · 2.81 Impact Factor -
Article: Are ambient water quality criteria for copper protective of olfactory impairment in fish?
Integrated Environmental Assessment and Management 01/2011; 7(1):145-6. -
Article: Protectiveness of water quality criteria for copper in western United States waters relative to predicted olfactory responses in juvenile Pacific salmon.
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ABSTRACT: Copper (Cu) can impair olfaction in juvenile Pacific salmon (as well as other fishes), thus potentially inhibiting the ability of juveniles to avoid predators or to find food. Because Cu is commonly elevated in stormwater runoff in urban environments, storm events may result in elevated Cu concentrations in salmon-bearing streams. Accordingly, there is concern that existing Cu criteria, which were not derived using data for olfactory-related endpoints, may not be adequately protective of juvenile salmon. However, a modification of the US Environmental Protection Agency (USEPA) biotic ligand model (BLM) for deriving site-specific Cu criteria was recently proposed, which accounted for the sensitivity of olfactory endpoints. The modification was based on olfactory inhibition in juvenile coho salmon (Oncorhynchus kisutch) exposed to Cu in various combinations of pH, hardness, alkalinity, and dissolved organic carbon (DOC) concentrations. We used that olfactory-based BLM to derive 20% inhibition concentrations (IC20) values for Cu for 133 stream locations in the western United States. The olfactory BLM-based IC20 values were compared to the existing hardness-based Cu criteria and the USEPA's BLM-based Cu criteria for these representative natural waters of the western United States. Of the 133 sampling locations, mean hardness-dependent acute and chronic Cu criteria were below the mean olfactory-based BLM IC20 value in 122 (92%) and 129 (97%) of the waters, respectively (i.e., <20% olfactory impairment would have been predicted at the mean hardness-based Cu criteria concentrations). Waters characterized by a combination of high hardness and very low DOC were most likely to have hardness-based Cu criteria that were higher than the olfactory-based BLM IC20 values, because DOC strongly influences Cu bioavailability in the BLM. In all waters, the USEPA's current BLM-based criteria were below the mean olfactory-based BLM IC20 values, indicating that the USEPA's BLM-based criteria are protective of olfactory impairment in juvenile salmon.Integrated Environmental Assessment and Management 11/2010; 7(3):336-47. -
Article: Shipboard trials of an ozone-based ballast water treatment system.
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ABSTRACT: Legislation introduced by the United Nations International Maritime Organization (IMO) has focused primarily on standards defining successful treatments designed to remove invasive species entrained in ballast water. An earlier shipboard study found that ozone introduced into salt water ballast resulted in the formation of bromine compounds, measured as total residual oxidants (TRO) that were toxic to both bacteria and plankton. However, the diffuser system employed to deliver ozone to the ballast water tanks resulted in patchiness in TRO distribution and toxicity to entrained organisms. In this follow-up study, the shipboard diffuser system was replaced by a single Venturi-type injection system designed to deliver a more homogeneous biocide distribution. Within-tank variability in TRO levels and associated toxicity to zooplankton, phytoplankton and marine bacteria was measured via a matrix of tubes deployed to sample different locations in treated and untreated (control) tanks. Three trials were conducted aboard the oil tanker S/T Prince William Sound in the Strait of Juan de Fuca off Port Angeles, Washington State, USA, between June and December 2007. Mortalities of plankton and bacteria and oxidant concentrations were recorded for treated and untreated ballast water up to 3days following treatment, and residual toxicity beyond this period was measured by bioassay of standard test organisms. Results indicated uniform compliance with current IMO standards, but only partial compliance with other existing and pending ballast water legislation.Marine pollution bulletin 09/2010; 60(9):1571-83. · 2.63 Impact Factor -
Article: Toxicity of ozonated seawater to marine organisms.
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ABSTRACT: Ballast water transport of nonindigenous species (NIS) is recognized as a significant contributor to biological invasions and a threat to coastal ecosystems. Recently, the use of ozone as an oxidant to eliminate NIS from ballast while ships are in transit has been considered. We determined the toxicity of ozone in artificial seawater (ASW) for five species of marine organisms in short-term (< or = 5 h) batch exposures. Larval topsmelt (Atherinops affinis) and juvenile sheepshead minnows (Cyprinodon variegatus) were the most sensitive to oxidant exposure, and the mysid shrimp (Americamysis bahia) was the most sensitive invertebrate. Conversely, benthic amphipods (Leptocheirus plumulosus and Rhepoxinius abronius) were the least sensitive of all species tested. Mortality from ozone exposure occurred quickly, with median lethal times ranging from 1 to 3 h for the most sensitive species, although additional mortality was observed 1 to 2 d following ozone exposure. Because ozone does not persist in seawater, toxicity likely resulted from bromide ion oxidation to bromine species (HOBr and OBr-), which persist as residual toxicants after at least 2 d of storage. Total residual oxidant (TRO; as Br2) formation resulting from ozone treatment was measured in ASW and four site-specific natural seawaters. The rate of TRO formation correlated with salinity, but dissolved organic carbon and total dissolved nitrogen did not affect TRO concentrations. Acute toxicity tests with each water over 48 h using mysid shrimp, topsmelt, and sheepshead minnows yielded results similar to those of batch exposure. Addition of sodium thiosulfate (Na2S2O3) to ozonated waters resulted in TRO elimination and survival of all organisms. Our results provide necessary information for the optimization of an efficacious ozone ballast water treatment system.Environmental Toxicology and Chemistry 10/2006; 25(10):2683-91. · 2.81 Impact Factor -
Article: Reassessment of Cyanide Ambient Water Quality Criteria: An Integrated Approach to Protection of the Aquatic Environment
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ABSTRACT: The U.S. Environmental Protection Agency's (USEPA) current ambient water quality criteria (AWQC) for cyanide were developed in 1984. Since this time, additional research on cyanide toxicity and analytical chemistry has suggested that cyanide AWQC values need to be updated to reflect the current state-of-the-science and to ensure that the methods for implementing the cyanide AWQC reflect the bioavailable and toxic forms of cyanide. Therefore, the Water Environment Research Foundation (WERF) sponsored a reassessment of the AWQC for cyanide by initiating a thorough review of the current scientific literature on cyanide and conducting additional laboratory studies to further understand cyanide chemistry and toxicity. Consistent with the USEPA's draft strategy for developing AWQC, this evaluation also considered whether the cyanide AWQC are protective of benthos, threatened and endangered (T&E) species, and aquatic-dependent wildlife. This reassessment of AWQC for cyanide resulted in proposed freshwater acute and chronic criteria of 23 and 4.8 μg CN/L, respectively, which are comparable to the current freshwater acute and chronic criteria of 22 and 5.2 μg CN/L (free cyanide). For saltwater organisms, the reassessment resulted in proposed acute and chronic criteria of 20 and 4.1 μg CN/L (free cyanide), respectively, compared to the current saltwater acute and chronic criteria which are both 1.0 μg CN/L. The difference in the current and proposed saltwater criteria values is attributed to recent cyanide toxicity testing with several crab species in the genus Cancer and the copepod Acartia tonsa, which suggests this genus is not as sensitive to cyanide as previous cyanide toxicity testing indicated. A sediment-based cyanide criterion does not appear warranted if it is assumed that benthic organisms are not inordinately more sensitive to cyanide than the water column organisms that drive the basis for the proposed freshwater and saltwater criteria (the available cyanide toxicity data do not suggest that they would be), and given that bioavailable forms of cyanide are not expected to accumulate appreciably in sediment. Cyanide should thus be effectively regulated based on water column-based criteria and concentrations. Based on a combination of available empirical and estimated cyanide toxicity values for T&E species, the proposed freshwater criteria appear to be protective of most T&E species, but any site-specific modifications that increase the cyanide AWQC for water bodies inhabited by T&E species is not recommended. Finally, the proposed freshwater AWQC for cyanide appear to be adequately protective of aquatic-dependent wildlife.Proceedings of the Water Environment Federation. 12/2005; -
Article: Effect of culture water hardness on the sensitivity of Ceriodaphnia dubia to copper toxicity.
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ABSTRACT: We examined whether the sensitivity of Ceriodaphnia dubia to copper toxicity was influenced by the hardness of the water in which they were reared or in which they were exposed. Organisms cultured in very hard water were 1.5-fold less sensitive to copper than those in moderately hard water. However, the hardness of the exposure water had a greater (2.5-fold) effect on copper median effective concentration (EC50s).Environmental Toxicology and Chemistry 07/2003; 22(6):1269-71. · 2.81 Impact Factor -
Article: Creosote toxicity to photosynthesis and plant growth in aquatic microcosms.
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ABSTRACT: To assess photosynthesis as a bioindicator of toxicity from polycyclic aromatic hydrocarbons (PAHs), the response of chlorophyll-a fluorescence to creosote exposure was compared with effects on population-level plant growth. Large, outdoor, freshwater microcosms containing Eurasian watermilfoil (Myriophyllum spicatum) received either a single application or multiple applications of liquid creosote at nominal concentrations from 0.109 to 32.7 mg L(-1). For several weeks following treatment, photosynthetic electron transport was measured using pulse amplitude-modulated chlorophyll-a fluorescence. The maximum efficiency of photosystem II electron transport (Fv/Fm) and the quantum yield of photochemistry (deltaF/F'm) were diminished in plants shortly after the addition of creosote. In microcosms that received a single treatment of creosote only, the 50% effective concentrations (EC50s), expressed as the aqueous concentration of 15 of the most abundant PAHs, were 0.28 mg L(-1) for Fv/Fm and 0.30 mg L(-1) for deltaF/F'm. Chlorophyll-a fluorescence was diminished to a greater extent in microcosms that received multiple treatments of creosote, with EC50s of 0.13 mg L(-1) for Fv/Fm and 0.10 mg L(-1) for deltaF/F'm. Plant biomass accumulation was inhibited in a concentration-dependent manner in all microcosms treated with creosote, but this inhibition occurred to a greater degree in microcosms treated with multiple creosote applications. The response of chlorophyll-a fluorescence, measured only 8 d after creosote treatment, was similar to plant growth over the entire growing season, indicating that this technique can be used to estimate potential effects of contaminants before detrimental impacts on populations.Environmental Toxicology and Chemistry 06/2003; 22(5):1075-85. · 2.81 Impact Factor -
Article: The biotic ligand model: a historical overview.
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ABSTRACT: During recent years, the biotic ligand model (BLM) has been proposed as a tool to evaluate quantitatively the manner in which water chemistry affects the speciation and biological availability of metals in aquatic systems. This is an important consideration because it is the bioavailability and bioreactivity of metals that control their potential to cause adverse effects. The BLM approach has gained widespread interest amongst the scientific, regulated and regulatory communities because of its potential for use in developing water quality criteria (WQC) and in performing aquatic risk assessments for metals. Specifically, the BLM does this in a way that considers the important influences of site-specific water quality. This journal issue includes papers that describe recent advances with regard to the development of the BLM approach. Here, the current status of the BLM development effort is described in the context of the longer-term history of advances in the understanding of metal interactions in the environment upon which the BLM is based. Early developments in the aquatic chemistry of metals, the physiology of aquatic organisms and aquatic toxicology are reviewed first, and the degree to which each of these disciplines influenced the development of water quality regulations is discussed. The early scientific advances that took place in each of these fields were not well coordinated, making it difficult for regulatory authorities to take full advantage of the potential utility of what had been learned. However, this has now changed, with the BLM serving as a useful interface amongst these scientific disciplines, and within the regulatory arena as well. The more recent events that have led to the present situation are reviewed, and consideration is given to some of the future needs and developments related to the BLM that are envisioned. The research results that are described in the papers found in this journal issue represent a distinct milestone in the ongoing evolution of the BLM approach and, more generally, of approaches to performing ecological assessments for metals in aquatic systems. These papers also establish a benchmark to which future scientific and regulatory developments can be compared. Finally, they demonstrate the importance and usefulness of the concept of bioavailability and of evaluative tools such as the BLM.Comparative Biochemistry and Physiology Part C Toxicology & Pharmacology 10/2002; 133(1-2):3-35. · 2.62 Impact Factor -
Article: Evaluating the role of ion composition on the toxicity of copper to Ceriodaphnia dubia in very hard waters.
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ABSTRACT: The mitigating effect of increasing hardness on metal toxicity is reflected in water quality criteria in the United States over the range of 25-400 mgl(-1) (as CaCO(3)). However, waters in the arid west of the US frequently exceed 400 mgl(-1) hardness, and the applicability of hardness-toxicity relationships in these waters is unknown. Acute toxicity tests with Ceriodaphnia dubia were conducted at hardness levels ranging from approximately 300 to 1,200 mgl(-1) using reconstituted waters that mimic two natural waters with elevated hardness: (1) alkaline desert southwest streams (Las Vegas Wash, NV), and (2) low alkalinity waters from a CaSO(4)-treated mining effluent in Colorado. The moderately-alkaline EPA synthetic hard water was also included for comparison. Copper toxicity did not consistently vary as a function of hardness, but likely as a function of other water quality characteristics (e.g., alkalinity or other correlated factors). The hardness equations used in regulatory criteria, therefore, may not provide an accurate level of protection against copper toxicity in all types of very hard waters. However, the mechanistic Biotic ligand model generally predicted copper toxicity within +/-2X of observed EC(50) values, and thus may be more useful than hardness for modifying water quality criteria.Comparative Biochemistry and Physiology Part C Toxicology & Pharmacology 10/2002; 133(1-2):87-97. · 2.62 Impact Factor -
Article: Response of phytoplankton communities to liquid creosote in freshwater microcosms
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ABSTRACT: We assessed the response of phytoplankton communities in aquatic microcosms to single applications of liquid creosote. The creosote was applied to 14 microcosms at concentrations ranging from 0.06 to 109 mg/L. Two microcosms served as controls. Phytoplankton samples were collected from each microcosm one week and 1 d before treatment and at 7 and 21 d after treatment. Temporal changes (response–recovery) in phytoplankton community composition were assessed with principal response curves. Creosote had no direct toxic effect on the phytoplankton community based on total abundance and number of taxa. Population levels declined in all treatments between day −1 and day 7, but this trend mirrored a similar decline in the control microcosms. At both 7 and 21 d after treatment, population densities and number of taxa in most treatments exceeded those in the controls and exhibited a parabolic relationship relative to creosote concentration. This relationship was most pronounced at 21 d, at which time population densities and number of taxa at intermediate concentrations were up to twice those at low and high concentrations. This response pattern seems to represent an indirect response to impacts on zooplankton and a corresponding reduction in grazing pressure. In contrast, total algal biomass declined 52 to 97% relative to the controls at all but the lowest creosote concentration at 7 d. This apparent decline was due to a significant proliferation of the alga Closterium moniliforme in the controls and low creosote concentration. At 21 d, no difference was found in total biomass between treated and control microcosms. The results of this study suggest that creosote does not pose a significant direct risk to phytoplankton at concentrations likely to be encountered in most contaminated aquatic environments; however, stimulation of algal populations could occur in situations of long-term chronic exposure or spill events that remove predatory zooplankton populations.Environmental Toxicology and Chemistry 11/2001; 20(12):2785 - 2793. · 2.81 Impact Factor -
Article: Copper accumulation on gills of fathead minnows: Influence of water hardness, complexation and pH of the gill micro‐environment
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ABSTRACT: Water pH in the gill micro-environment of adult fathead minnows (Pimephales promelas Rafinesque) was measured by means of opercular catheters and latex masks. Synthetic soft water of pH <5.7 was rendered more basic as it passed over the gills and water of pH >5.7 was made more acidic, so that pH of the gill micro-environment stayed at approximately 5.4 to 5.9 over the inspired pH range 4.8 to 6.3. Copper would therefore be >99% Cu2+ at the gills. To measure Cu accumulation on gills, the target organ for Cu toxicity, adult fathead minnows were exposed for 2 to 3 h to 16 μg/L Cu in synthetic soft water (Ca2+ and Na+ approximately 50 μeq/L) at pH 4.8 and 6.3. Gill Cu concentrations were about 1.7 μg Cu/g wet tissue for the inspired pH 4.8 and 6.3 exposures. Added Ca2+ of 2,100 or 4,000 μeq/L reduced gill Cu accumulation during exposures at pH 4.8 but not at pH 6.3. EDTA eliminated Cu deposition at both pH 4.8 and pH 6.3 when equimolar with Cu, but reduced Cu deposition (by 50%) when half equimolar only in the pH 4.8 exposures. These results can be explained by Ca2+ and H+ competition with Cu for gill binding sites and by complexation of Cu by EDTA. Added CaCO3 did not reduce gill Cu, although both competition by Ca2+ and complexation by CO2−3 were expected. Water chemistry calculations suggested that because little CO2−3 is available at pH < 7, CO2−3 from CaCO3 is less likely to affect Cu deposition on fish gills than is Ca2+ from CaCO3.Environmental Toxicology and Chemistry 02/1992; 11(3):381 - 391. · 2.81 Impact Factor
