The Experts below are selected from a list of 390 Experts worldwide ranked by ideXlab platform

John H Rodgers - One of the best experts on this subject based on the ideXlab platform.

  • Laboratory-scale evaluation of Algaecide effectiveness for control of microcystin-producing cyanobacteria from Lake Okeechobee, Florida (USA)
    Ecotoxicology and environmental safety, 2020
    Co-Authors: Ciera Kinley-baird, Alyssa J Calomeni, John H Rodgers, David E. Berthold, Forrest W. Lefler, Maximiliano Barbosa, H. Dail Laughinghouse
    Abstract:

    Growth of microcystin-producing cyanobacteria in Lake Okeechobee (Florida, USA) and surrounding waters has resulted in adverse health impacts for humans and endangered species, as well as significant economic losses. As these issues worsen, there is growing pressure for efficacious solutions to rapidly mitigate harmful algal blooms (HABs) and protect critical freshwater resources. Applications of USEPA-registered Algaecides as management tactics meet many decision-making criteria often required by water resource managers (e.g., effective, scalable, selective), but have not yet been evaluated on a large scale within the Lake Okeechobee waterway. This study was conducted to bolster the peer-reviewed database for available management tactics against microcystin-producing cyanobacteria in waters of this region. Laboratory-scale experiments can be conducted first to minimize uncertainty at larger scales and improve confidence in decision-making. In this study, samples containing microcystin-producing cyanobacteria collected from Lake Okeechobee were exposed to several USEPA-registered Algaecides in laboratory toxicity experiments. Responses of target cyanobacteria were measured 3 days after treatment (DAT) in terms of cell density, chlorophyll-a concentrations, and phycocyanin concentrations. Based on responses of the cyanobacteria, minimum effective exposure concentrations were identified for each Algaecide. Microcystin release (i.e. proportion of total microcystins in the aqueous phase) was measured and compared 1 DAT among effective exposures. Total microcystin concentrations were measured in effective treatments at 1, 4, and 9 DAT to discern potential for microcystin persistence following exposures to the effective formulations and exposure concentrations. Overall, several formulations including GreenClean Liquid® 5.0, GreenClean Liquid® 5.0 combined with Hydrothol® 191, and the copper-based Algaecides evaluated (Algimycin® PWF, Argos, Captain® XTR, Cutrine® Ultra, and SeClear®) achieved significant and similar effects on target cyanobacteria. The chelated copper-based formulations (Algimycin® PWF, Argos, Captain® XTR, and Cutrine® Ultra) resulted in relatively less microcystin release 1 DAT and lesser total microcystin concentrations 4 DAT. At 9 DAT, total microcystin concentrations were significantly lower than in untreated controls in all treatments evaluated. These results provide the necessary comparative performance data for preliminary decision-making and designing additional studies at larger scales. Importantly, the comparative toxicity data and approach provided in this study demonstrate the initial steps for development of site-specific management strategies for Lake Okeechobee and other areas impacted by harmful algal blooms with large spatial and temporal scales.

  • microcystin lr degradation following copper based Algaecide exposures
    Water Air and Soil Pollution, 2018
    Co-Authors: Ciera M Kinley, Andrew D Mcqueen, Alyssa J Calomeni, Maas Hendrikse, Tyler D. Geer, Jenny Liang, Vanessa Friesen, Kyla J Iwinskiwood, Monique C Simair, John H Rodgers
    Abstract:

    When copper-based Algaecides are used in aquatic systems to decrease cyanobacteria densities, endotoxin fate is a concern, due to the potential for human health and ecological risks. Pulse exposures of Algaecides can result in episodic low dissolved oxygen (DO) concentrations (< 2 mg L−1), due to oxygen consumed via microbial oxidation of algal detritus. Research objectives of this study were to determine the influence of declining DO levels on microcystin-LR (MC-LR) degradation and changes in resident bacterial assemblages. It was hypothesized that cyanobacteria cell densities would be positively correlated with rates and extents of DO decline based on the oxygen required for bacteria to degrade cyanobacteria detritus following exposure to copper-based Algaecides. In addition, it was hypothesized that total MC-LR concentrations would increase proportionally with increasing cyanobacteria cell densities. Mesocosm experiments were conducted in a pond in Anderson, SC, that frequently experiences cyanobacteria blooms. Three densities of a cyanobacteria assemblage were exposed to a copper ethanolamine Algaecide. DO and total MC-LR concentrations were measured with time following Algaecide exposures to determine rates and extents of declines. As anticipated, DO concentrations had the highest rate of decline in the highest cell density treatment, followed by medium and low cell densities. MC-LR degradation occurred at similar rates (half-lives 1 to 1.9 days) among cell densities. Acinetobacter and Aeromonas were dominant in treatments following copper exposures. The relationship between cyanobacteria densities and MC-LR half-lives demonstrates the benefits of managing cyanobacteria in early growth stages to minimize MC concentrations.

  • Characterization of Copper Algaecide (Copper Ethanolamine) Dissipation Rates Following Pulse Exposures
    Water Air & Soil Pollution, 2017
    Co-Authors: Alyssa J Calomeni, Andrew D Mcqueen, Ciera M Kinley, Kyla J Iwinski, Maas Hendrikse, John H Rodgers
    Abstract:

    Dissipation rates of copper following Algaecide treatments resulting in pulse exposures can be accurately modeled if the component dissipation rates are known. Scaled experiments (in situ, laboratory and mesocosm) were used to parse and rank dominant processes from concurrent processes affecting copper fate in pulse exposures. Copper dissipation rates were measured cumulatively in situ and in mesocosms as well as individually in laboratory experiments. Predictions of the influence of individual dissipation rates on the cumulative dissipation rate were assessed mathematically. In situ aqueous copper dissipated rapidly following an Algaecide treatment, with a measured half-life of 0.03 days. Based on laboratory experiments, the most rapid copper fate process was dilution with a half-life of 0.03 days, followed by sediment sorption with a half-life of approximately 3 days. Mesocosm experiments incorporating physical characteristics of the site (i.e., dilution, sediment, algae, and site water) resulted in similar copper dissipation rates (0.02 days) relative to the in situ copper dissipation rate. Prediction of the fate of copper from Algaecide treatments requires incorporation of accurate estimates of dominant fate processes that can be determined physically and mathematically.

  • Cell density dependence of Microcystis aeruginosa responses to copper Algaecide concentrations: Implications for microcystin-LR release.
    Ecotoxicology and environmental safety, 2017
    Co-Authors: Ciera M Kinley, Kyla J Iwinski, Maas Hendrikse, Tyler D. Geer, John H Rodgers
    Abstract:

    Along with mechanistic models, predictions of exposure-response relationships for copper are often derived from laboratory toxicity experiments with standardized experimental exposures and conditions. For predictions of copper toxicity to algae, cell density is a critical factor often overlooked. For pulse exposures of copper-based Algaecides in aquatic systems, cell density can significantly influence copper sorbed by the algal population, and consequent responses. A cyanobacterium, Microcystis aeruginosa, was exposed to a copper-based Algaecide over a range of cell densities to model the density-dependence of exposures, and effects on microcystin-LR (MC-LR) release. Copper exposure concentrations were arrayed to result in a gradient of MC-LR release, and masses of copper sorbed to algal populations were measured following exposures. While copper exposure concentrations eliciting comparable MC-LR release ranged an order of magnitude (24-h EC50s 0.03-0.3mg Cu/L) among cell densities of 106 through 107 cells/mL, copper doses (mg Cu/mg algae) were similar (24-h EC50s 0.005-0.006mg Cu/mg algae). Comparisons of MC-LR release as a function of copper exposure concentrations and doses provided a metric of the density dependence of algal responses in the context of copper-based Algaecide applications. Combined with estimates of other site-specific factors (e.g. water characteristics) and fate processes (e.g. dilution and dispersion, sorption to organic matter and sediments), measuring exposure-response relationships for specific cell densities can refine predictions for in situ exposures and algal responses. These measurements can in turn decrease the likelihood of amending unnecessary copper concentrations to aquatic systems, and minimize risks for non-target aquatic organisms.

  • Influence of CuSO4 and chelated copper Algaecide exposures on biodegradation of microcystin-LR.
    Chemosphere, 2017
    Co-Authors: Kyla J Iwinski, Andrew D Mcqueen, Ciera M Kinley, Alyssa J Calomeni, John H Rodgers, Maas Hendrikse, Tyler D. Geer, Jenny Liang, Vanessa Friesen, Monique Haakensen
    Abstract:

    Abstract Copper exposures from Algaecide applications in aquatic systems are hypothesized to impede bacterial degradation of microcystin (MC), a cyanobacterial produced hepatotoxin. Despite regulatory implications of this hypothesis, limited data exist on influences of copper-exposures on MC-degrading bacteria and consequent MC-degradation. In this study, influences of copper-Algaecide concentrations and formulations on bacterial composition and microcystin-LR (MCLR) degradation were investigated. Microcystis aeruginosa was exposed to four concentrations (0–5.0 mg Cu L−1) of three copper-Algaecide formulations, and rates and extents of MCLR degradation were measured. In untreated controls and following exposures of 0.1, 0.5, and 1.0 mg Cu L−1, MCLR concentrations decreased at a rate of ∼41–53 μg MCLR/L d−1. Following exposure to 5.0 mg Cu L−1 MCLR degradation rates decreased an order of magnitude to ∼3–7 μg MCLR/L d−1. Bacterial diversity decreased following copper-exposures greater than 0.1 mg Cu L−1 for all formulations. Relative abundance of certain groups of MC-degrading bacteria identified in treatments increased with increasing copper concentration, suggesting they may be less sensitive to copper exposures than other, MCLR and non MC-degrading heterotrophic bacteria present in the assemblage. Results from this study revealed that copper concentration can influence degradation rates of MCLR, however this influence was not significant within copper concentrations currently registered for use (≤1.0 mg Cu L−1) of the tested Algaecides. Copper formulation did not significantly alter degradation rates or bacterial composition. These data augment our understanding of the influences of copper Algaecide-exposures on MCLR degradation, and can be used to inform more accurate risk evaluations and use of copper-Algaecides for management of MCLR-producing cyanobacteria.

Ciera M Kinley - One of the best experts on this subject based on the ideXlab platform.

  • microcystin lr degradation following copper based Algaecide exposures
    Water Air and Soil Pollution, 2018
    Co-Authors: Ciera M Kinley, Andrew D Mcqueen, Alyssa J Calomeni, Maas Hendrikse, Tyler D. Geer, Jenny Liang, Vanessa Friesen, Kyla J Iwinskiwood, Monique C Simair, John H Rodgers
    Abstract:

    When copper-based Algaecides are used in aquatic systems to decrease cyanobacteria densities, endotoxin fate is a concern, due to the potential for human health and ecological risks. Pulse exposures of Algaecides can result in episodic low dissolved oxygen (DO) concentrations (< 2 mg L−1), due to oxygen consumed via microbial oxidation of algal detritus. Research objectives of this study were to determine the influence of declining DO levels on microcystin-LR (MC-LR) degradation and changes in resident bacterial assemblages. It was hypothesized that cyanobacteria cell densities would be positively correlated with rates and extents of DO decline based on the oxygen required for bacteria to degrade cyanobacteria detritus following exposure to copper-based Algaecides. In addition, it was hypothesized that total MC-LR concentrations would increase proportionally with increasing cyanobacteria cell densities. Mesocosm experiments were conducted in a pond in Anderson, SC, that frequently experiences cyanobacteria blooms. Three densities of a cyanobacteria assemblage were exposed to a copper ethanolamine Algaecide. DO and total MC-LR concentrations were measured with time following Algaecide exposures to determine rates and extents of declines. As anticipated, DO concentrations had the highest rate of decline in the highest cell density treatment, followed by medium and low cell densities. MC-LR degradation occurred at similar rates (half-lives 1 to 1.9 days) among cell densities. Acinetobacter and Aeromonas were dominant in treatments following copper exposures. The relationship between cyanobacteria densities and MC-LR half-lives demonstrates the benefits of managing cyanobacteria in early growth stages to minimize MC concentrations.

  • Characterization of Copper Algaecide (Copper Ethanolamine) Dissipation Rates Following Pulse Exposures
    Water Air & Soil Pollution, 2017
    Co-Authors: Alyssa J Calomeni, Andrew D Mcqueen, Ciera M Kinley, Kyla J Iwinski, Maas Hendrikse, John H Rodgers
    Abstract:

    Dissipation rates of copper following Algaecide treatments resulting in pulse exposures can be accurately modeled if the component dissipation rates are known. Scaled experiments (in situ, laboratory and mesocosm) were used to parse and rank dominant processes from concurrent processes affecting copper fate in pulse exposures. Copper dissipation rates were measured cumulatively in situ and in mesocosms as well as individually in laboratory experiments. Predictions of the influence of individual dissipation rates on the cumulative dissipation rate were assessed mathematically. In situ aqueous copper dissipated rapidly following an Algaecide treatment, with a measured half-life of 0.03 days. Based on laboratory experiments, the most rapid copper fate process was dilution with a half-life of 0.03 days, followed by sediment sorption with a half-life of approximately 3 days. Mesocosm experiments incorporating physical characteristics of the site (i.e., dilution, sediment, algae, and site water) resulted in similar copper dissipation rates (0.02 days) relative to the in situ copper dissipation rate. Prediction of the fate of copper from Algaecide treatments requires incorporation of accurate estimates of dominant fate processes that can be determined physically and mathematically.

  • Cell density dependence of Microcystis aeruginosa responses to copper Algaecide concentrations: Implications for microcystin-LR release.
    Ecotoxicology and environmental safety, 2017
    Co-Authors: Ciera M Kinley, Kyla J Iwinski, Maas Hendrikse, Tyler D. Geer, John H Rodgers
    Abstract:

    Along with mechanistic models, predictions of exposure-response relationships for copper are often derived from laboratory toxicity experiments with standardized experimental exposures and conditions. For predictions of copper toxicity to algae, cell density is a critical factor often overlooked. For pulse exposures of copper-based Algaecides in aquatic systems, cell density can significantly influence copper sorbed by the algal population, and consequent responses. A cyanobacterium, Microcystis aeruginosa, was exposed to a copper-based Algaecide over a range of cell densities to model the density-dependence of exposures, and effects on microcystin-LR (MC-LR) release. Copper exposure concentrations were arrayed to result in a gradient of MC-LR release, and masses of copper sorbed to algal populations were measured following exposures. While copper exposure concentrations eliciting comparable MC-LR release ranged an order of magnitude (24-h EC50s 0.03-0.3mg Cu/L) among cell densities of 106 through 107 cells/mL, copper doses (mg Cu/mg algae) were similar (24-h EC50s 0.005-0.006mg Cu/mg algae). Comparisons of MC-LR release as a function of copper exposure concentrations and doses provided a metric of the density dependence of algal responses in the context of copper-based Algaecide applications. Combined with estimates of other site-specific factors (e.g. water characteristics) and fate processes (e.g. dilution and dispersion, sorption to organic matter and sediments), measuring exposure-response relationships for specific cell densities can refine predictions for in situ exposures and algal responses. These measurements can in turn decrease the likelihood of amending unnecessary copper concentrations to aquatic systems, and minimize risks for non-target aquatic organisms.

  • Influence of CuSO4 and chelated copper Algaecide exposures on biodegradation of microcystin-LR.
    Chemosphere, 2017
    Co-Authors: Kyla J Iwinski, Andrew D Mcqueen, Ciera M Kinley, Alyssa J Calomeni, John H Rodgers, Maas Hendrikse, Tyler D. Geer, Jenny Liang, Vanessa Friesen, Monique Haakensen
    Abstract:

    Abstract Copper exposures from Algaecide applications in aquatic systems are hypothesized to impede bacterial degradation of microcystin (MC), a cyanobacterial produced hepatotoxin. Despite regulatory implications of this hypothesis, limited data exist on influences of copper-exposures on MC-degrading bacteria and consequent MC-degradation. In this study, influences of copper-Algaecide concentrations and formulations on bacterial composition and microcystin-LR (MCLR) degradation were investigated. Microcystis aeruginosa was exposed to four concentrations (0–5.0 mg Cu L−1) of three copper-Algaecide formulations, and rates and extents of MCLR degradation were measured. In untreated controls and following exposures of 0.1, 0.5, and 1.0 mg Cu L−1, MCLR concentrations decreased at a rate of ∼41–53 μg MCLR/L d−1. Following exposure to 5.0 mg Cu L−1 MCLR degradation rates decreased an order of magnitude to ∼3–7 μg MCLR/L d−1. Bacterial diversity decreased following copper-exposures greater than 0.1 mg Cu L−1 for all formulations. Relative abundance of certain groups of MC-degrading bacteria identified in treatments increased with increasing copper concentration, suggesting they may be less sensitive to copper exposures than other, MCLR and non MC-degrading heterotrophic bacteria present in the assemblage. Results from this study revealed that copper concentration can influence degradation rates of MCLR, however this influence was not significant within copper concentrations currently registered for use (≤1.0 mg Cu L−1) of the tested Algaecides. Copper formulation did not significantly alter degradation rates or bacterial composition. These data augment our understanding of the influences of copper Algaecide-exposures on MCLR degradation, and can be used to inform more accurate risk evaluations and use of copper-Algaecides for management of MCLR-producing cyanobacteria.

  • Predicting In Situ Responses of Taste- and Odor-Producing Algae in a Southeastern US Reservoir to a Sodium Carbonate Peroxyhydrate Algaecide Using a Laboratory Exposure-Response Model
    Water Air & Soil Pollution, 2017
    Co-Authors: Tyler D. Geer, Ciera M Kinley, Kyla J Iwinski, Alyssa J Calomeni, John H Rodgers
    Abstract:

    Efficacy of an in situ Algaecide treatment can be predicted prior to an application by physically modeling exposures and responses with laboratory experiments. A sodium carbonate peroxyhydrate (SCP) Algaecide was used in a drinking water reservoir (Hartwell Lake, Anderson, SC) to control a benthic algal assemblage putatively producing 2-methylisoboreol (MIB) and geosmin, compounds with adverse taste and odor attributes. These SCP applications provided an opportunity to test hypotheses regarding potential convergence of laboratory and in situ exposures and responses. Objectives of this study were to (1) measure responses of a benthic algal assemblage from Hartwell Lake to 7-day laboratory exposures of SCP [measured as hydrogen peroxide (H_2O_2) concentrations], (2) to measure the exposure of SCP (as H_2O_2) applied in a cove of Hartwell Lake and consequent responses of the algal assemblage, and (3) compare exposures and responses measured in the laboratory and in situ. Results demonstrated that in laboratory exposures, H_2O_2 released by SCP dissipated within 48 h. Significant responses of the algal assemblage in terms of phycocyanin concentrations and cell densities were measured 4 days after treatment (4-DAT) and 7-DAT following exposures of 453, 615, and 812 mg H_2O_2 m^−2. The H_2O_2 exposure measured in situ was comparable to effective laboratory exposures in terms of initial exposure (619 ± 428 mg H_2O_2 m^−2) and exposure duration (dissipation within 30 h), but the in situ exposure had a large deviation initially (i.e., ±428 mg H_2O_2 m^−2) and was an order of magnitude less than the targeted initial exposure. Therefore, comparison of measured responses was critical to infer comparable exposures and confirm accuracy of the laboratory model. Significant in situ responses were measured 4-DAT and 7-DAT in terms of phycocyanin concentrations and cell densities, and were comparable to responses obtained from effective laboratory exposures (i.e., 453, 615, and 812 mg H_2O_2 m^−2). Decreases in measured concentrations of MIB and geosmin at the intake of the drinking water treatment facility provided additional evidence that algae were sufficiently exposed to H_2O_2 from SCP. Results of this experiment provide evidence for the design and use of physical laboratory models to predict responses of algae in the field.

Alyssa J Calomeni - One of the best experts on this subject based on the ideXlab platform.

  • Laboratory-scale evaluation of Algaecide effectiveness for control of microcystin-producing cyanobacteria from Lake Okeechobee, Florida (USA)
    Ecotoxicology and environmental safety, 2020
    Co-Authors: Ciera Kinley-baird, Alyssa J Calomeni, John H Rodgers, David E. Berthold, Forrest W. Lefler, Maximiliano Barbosa, H. Dail Laughinghouse
    Abstract:

    Growth of microcystin-producing cyanobacteria in Lake Okeechobee (Florida, USA) and surrounding waters has resulted in adverse health impacts for humans and endangered species, as well as significant economic losses. As these issues worsen, there is growing pressure for efficacious solutions to rapidly mitigate harmful algal blooms (HABs) and protect critical freshwater resources. Applications of USEPA-registered Algaecides as management tactics meet many decision-making criteria often required by water resource managers (e.g., effective, scalable, selective), but have not yet been evaluated on a large scale within the Lake Okeechobee waterway. This study was conducted to bolster the peer-reviewed database for available management tactics against microcystin-producing cyanobacteria in waters of this region. Laboratory-scale experiments can be conducted first to minimize uncertainty at larger scales and improve confidence in decision-making. In this study, samples containing microcystin-producing cyanobacteria collected from Lake Okeechobee were exposed to several USEPA-registered Algaecides in laboratory toxicity experiments. Responses of target cyanobacteria were measured 3 days after treatment (DAT) in terms of cell density, chlorophyll-a concentrations, and phycocyanin concentrations. Based on responses of the cyanobacteria, minimum effective exposure concentrations were identified for each Algaecide. Microcystin release (i.e. proportion of total microcystins in the aqueous phase) was measured and compared 1 DAT among effective exposures. Total microcystin concentrations were measured in effective treatments at 1, 4, and 9 DAT to discern potential for microcystin persistence following exposures to the effective formulations and exposure concentrations. Overall, several formulations including GreenClean Liquid® 5.0, GreenClean Liquid® 5.0 combined with Hydrothol® 191, and the copper-based Algaecides evaluated (Algimycin® PWF, Argos, Captain® XTR, Cutrine® Ultra, and SeClear®) achieved significant and similar effects on target cyanobacteria. The chelated copper-based formulations (Algimycin® PWF, Argos, Captain® XTR, and Cutrine® Ultra) resulted in relatively less microcystin release 1 DAT and lesser total microcystin concentrations 4 DAT. At 9 DAT, total microcystin concentrations were significantly lower than in untreated controls in all treatments evaluated. These results provide the necessary comparative performance data for preliminary decision-making and designing additional studies at larger scales. Importantly, the comparative toxicity data and approach provided in this study demonstrate the initial steps for development of site-specific management strategies for Lake Okeechobee and other areas impacted by harmful algal blooms with large spatial and temporal scales.

  • microcystin lr degradation following copper based Algaecide exposures
    Water Air and Soil Pollution, 2018
    Co-Authors: Ciera M Kinley, Andrew D Mcqueen, Alyssa J Calomeni, Maas Hendrikse, Tyler D. Geer, Jenny Liang, Vanessa Friesen, Kyla J Iwinskiwood, Monique C Simair, John H Rodgers
    Abstract:

    When copper-based Algaecides are used in aquatic systems to decrease cyanobacteria densities, endotoxin fate is a concern, due to the potential for human health and ecological risks. Pulse exposures of Algaecides can result in episodic low dissolved oxygen (DO) concentrations (< 2 mg L−1), due to oxygen consumed via microbial oxidation of algal detritus. Research objectives of this study were to determine the influence of declining DO levels on microcystin-LR (MC-LR) degradation and changes in resident bacterial assemblages. It was hypothesized that cyanobacteria cell densities would be positively correlated with rates and extents of DO decline based on the oxygen required for bacteria to degrade cyanobacteria detritus following exposure to copper-based Algaecides. In addition, it was hypothesized that total MC-LR concentrations would increase proportionally with increasing cyanobacteria cell densities. Mesocosm experiments were conducted in a pond in Anderson, SC, that frequently experiences cyanobacteria blooms. Three densities of a cyanobacteria assemblage were exposed to a copper ethanolamine Algaecide. DO and total MC-LR concentrations were measured with time following Algaecide exposures to determine rates and extents of declines. As anticipated, DO concentrations had the highest rate of decline in the highest cell density treatment, followed by medium and low cell densities. MC-LR degradation occurred at similar rates (half-lives 1 to 1.9 days) among cell densities. Acinetobacter and Aeromonas were dominant in treatments following copper exposures. The relationship between cyanobacteria densities and MC-LR half-lives demonstrates the benefits of managing cyanobacteria in early growth stages to minimize MC concentrations.

  • Characterization of Copper Algaecide (Copper Ethanolamine) Dissipation Rates Following Pulse Exposures
    Water Air & Soil Pollution, 2017
    Co-Authors: Alyssa J Calomeni, Andrew D Mcqueen, Ciera M Kinley, Kyla J Iwinski, Maas Hendrikse, John H Rodgers
    Abstract:

    Dissipation rates of copper following Algaecide treatments resulting in pulse exposures can be accurately modeled if the component dissipation rates are known. Scaled experiments (in situ, laboratory and mesocosm) were used to parse and rank dominant processes from concurrent processes affecting copper fate in pulse exposures. Copper dissipation rates were measured cumulatively in situ and in mesocosms as well as individually in laboratory experiments. Predictions of the influence of individual dissipation rates on the cumulative dissipation rate were assessed mathematically. In situ aqueous copper dissipated rapidly following an Algaecide treatment, with a measured half-life of 0.03 days. Based on laboratory experiments, the most rapid copper fate process was dilution with a half-life of 0.03 days, followed by sediment sorption with a half-life of approximately 3 days. Mesocosm experiments incorporating physical characteristics of the site (i.e., dilution, sediment, algae, and site water) resulted in similar copper dissipation rates (0.02 days) relative to the in situ copper dissipation rate. Prediction of the fate of copper from Algaecide treatments requires incorporation of accurate estimates of dominant fate processes that can be determined physically and mathematically.

  • Influence of CuSO4 and chelated copper Algaecide exposures on biodegradation of microcystin-LR.
    Chemosphere, 2017
    Co-Authors: Kyla J Iwinski, Andrew D Mcqueen, Ciera M Kinley, Alyssa J Calomeni, John H Rodgers, Maas Hendrikse, Tyler D. Geer, Jenny Liang, Vanessa Friesen, Monique Haakensen
    Abstract:

    Abstract Copper exposures from Algaecide applications in aquatic systems are hypothesized to impede bacterial degradation of microcystin (MC), a cyanobacterial produced hepatotoxin. Despite regulatory implications of this hypothesis, limited data exist on influences of copper-exposures on MC-degrading bacteria and consequent MC-degradation. In this study, influences of copper-Algaecide concentrations and formulations on bacterial composition and microcystin-LR (MCLR) degradation were investigated. Microcystis aeruginosa was exposed to four concentrations (0–5.0 mg Cu L−1) of three copper-Algaecide formulations, and rates and extents of MCLR degradation were measured. In untreated controls and following exposures of 0.1, 0.5, and 1.0 mg Cu L−1, MCLR concentrations decreased at a rate of ∼41–53 μg MCLR/L d−1. Following exposure to 5.0 mg Cu L−1 MCLR degradation rates decreased an order of magnitude to ∼3–7 μg MCLR/L d−1. Bacterial diversity decreased following copper-exposures greater than 0.1 mg Cu L−1 for all formulations. Relative abundance of certain groups of MC-degrading bacteria identified in treatments increased with increasing copper concentration, suggesting they may be less sensitive to copper exposures than other, MCLR and non MC-degrading heterotrophic bacteria present in the assemblage. Results from this study revealed that copper concentration can influence degradation rates of MCLR, however this influence was not significant within copper concentrations currently registered for use (≤1.0 mg Cu L−1) of the tested Algaecides. Copper formulation did not significantly alter degradation rates or bacterial composition. These data augment our understanding of the influences of copper Algaecide-exposures on MCLR degradation, and can be used to inform more accurate risk evaluations and use of copper-Algaecides for management of MCLR-producing cyanobacteria.

  • Predicting In Situ Responses of Taste- and Odor-Producing Algae in a Southeastern US Reservoir to a Sodium Carbonate Peroxyhydrate Algaecide Using a Laboratory Exposure-Response Model
    Water Air & Soil Pollution, 2017
    Co-Authors: Tyler D. Geer, Ciera M Kinley, Kyla J Iwinski, Alyssa J Calomeni, John H Rodgers
    Abstract:

    Efficacy of an in situ Algaecide treatment can be predicted prior to an application by physically modeling exposures and responses with laboratory experiments. A sodium carbonate peroxyhydrate (SCP) Algaecide was used in a drinking water reservoir (Hartwell Lake, Anderson, SC) to control a benthic algal assemblage putatively producing 2-methylisoboreol (MIB) and geosmin, compounds with adverse taste and odor attributes. These SCP applications provided an opportunity to test hypotheses regarding potential convergence of laboratory and in situ exposures and responses. Objectives of this study were to (1) measure responses of a benthic algal assemblage from Hartwell Lake to 7-day laboratory exposures of SCP [measured as hydrogen peroxide (H_2O_2) concentrations], (2) to measure the exposure of SCP (as H_2O_2) applied in a cove of Hartwell Lake and consequent responses of the algal assemblage, and (3) compare exposures and responses measured in the laboratory and in situ. Results demonstrated that in laboratory exposures, H_2O_2 released by SCP dissipated within 48 h. Significant responses of the algal assemblage in terms of phycocyanin concentrations and cell densities were measured 4 days after treatment (4-DAT) and 7-DAT following exposures of 453, 615, and 812 mg H_2O_2 m^−2. The H_2O_2 exposure measured in situ was comparable to effective laboratory exposures in terms of initial exposure (619 ± 428 mg H_2O_2 m^−2) and exposure duration (dissipation within 30 h), but the in situ exposure had a large deviation initially (i.e., ±428 mg H_2O_2 m^−2) and was an order of magnitude less than the targeted initial exposure. Therefore, comparison of measured responses was critical to infer comparable exposures and confirm accuracy of the laboratory model. Significant in situ responses were measured 4-DAT and 7-DAT in terms of phycocyanin concentrations and cell densities, and were comparable to responses obtained from effective laboratory exposures (i.e., 453, 615, and 812 mg H_2O_2 m^−2). Decreases in measured concentrations of MIB and geosmin at the intake of the drinking water treatment facility provided additional evidence that algae were sufficiently exposed to H_2O_2 from SCP. Results of this experiment provide evidence for the design and use of physical laboratory models to predict responses of algae in the field.

Kyla J Iwinski - One of the best experts on this subject based on the ideXlab platform.

  • Characterization of Copper Algaecide (Copper Ethanolamine) Dissipation Rates Following Pulse Exposures
    Water Air & Soil Pollution, 2017
    Co-Authors: Alyssa J Calomeni, Andrew D Mcqueen, Ciera M Kinley, Kyla J Iwinski, Maas Hendrikse, John H Rodgers
    Abstract:

    Dissipation rates of copper following Algaecide treatments resulting in pulse exposures can be accurately modeled if the component dissipation rates are known. Scaled experiments (in situ, laboratory and mesocosm) were used to parse and rank dominant processes from concurrent processes affecting copper fate in pulse exposures. Copper dissipation rates were measured cumulatively in situ and in mesocosms as well as individually in laboratory experiments. Predictions of the influence of individual dissipation rates on the cumulative dissipation rate were assessed mathematically. In situ aqueous copper dissipated rapidly following an Algaecide treatment, with a measured half-life of 0.03 days. Based on laboratory experiments, the most rapid copper fate process was dilution with a half-life of 0.03 days, followed by sediment sorption with a half-life of approximately 3 days. Mesocosm experiments incorporating physical characteristics of the site (i.e., dilution, sediment, algae, and site water) resulted in similar copper dissipation rates (0.02 days) relative to the in situ copper dissipation rate. Prediction of the fate of copper from Algaecide treatments requires incorporation of accurate estimates of dominant fate processes that can be determined physically and mathematically.

  • Cell density dependence of Microcystis aeruginosa responses to copper Algaecide concentrations: Implications for microcystin-LR release.
    Ecotoxicology and environmental safety, 2017
    Co-Authors: Ciera M Kinley, Kyla J Iwinski, Maas Hendrikse, Tyler D. Geer, John H Rodgers
    Abstract:

    Along with mechanistic models, predictions of exposure-response relationships for copper are often derived from laboratory toxicity experiments with standardized experimental exposures and conditions. For predictions of copper toxicity to algae, cell density is a critical factor often overlooked. For pulse exposures of copper-based Algaecides in aquatic systems, cell density can significantly influence copper sorbed by the algal population, and consequent responses. A cyanobacterium, Microcystis aeruginosa, was exposed to a copper-based Algaecide over a range of cell densities to model the density-dependence of exposures, and effects on microcystin-LR (MC-LR) release. Copper exposure concentrations were arrayed to result in a gradient of MC-LR release, and masses of copper sorbed to algal populations were measured following exposures. While copper exposure concentrations eliciting comparable MC-LR release ranged an order of magnitude (24-h EC50s 0.03-0.3mg Cu/L) among cell densities of 106 through 107 cells/mL, copper doses (mg Cu/mg algae) were similar (24-h EC50s 0.005-0.006mg Cu/mg algae). Comparisons of MC-LR release as a function of copper exposure concentrations and doses provided a metric of the density dependence of algal responses in the context of copper-based Algaecide applications. Combined with estimates of other site-specific factors (e.g. water characteristics) and fate processes (e.g. dilution and dispersion, sorption to organic matter and sediments), measuring exposure-response relationships for specific cell densities can refine predictions for in situ exposures and algal responses. These measurements can in turn decrease the likelihood of amending unnecessary copper concentrations to aquatic systems, and minimize risks for non-target aquatic organisms.

  • Influence of CuSO4 and chelated copper Algaecide exposures on biodegradation of microcystin-LR.
    Chemosphere, 2017
    Co-Authors: Kyla J Iwinski, Andrew D Mcqueen, Ciera M Kinley, Alyssa J Calomeni, John H Rodgers, Maas Hendrikse, Tyler D. Geer, Jenny Liang, Vanessa Friesen, Monique Haakensen
    Abstract:

    Abstract Copper exposures from Algaecide applications in aquatic systems are hypothesized to impede bacterial degradation of microcystin (MC), a cyanobacterial produced hepatotoxin. Despite regulatory implications of this hypothesis, limited data exist on influences of copper-exposures on MC-degrading bacteria and consequent MC-degradation. In this study, influences of copper-Algaecide concentrations and formulations on bacterial composition and microcystin-LR (MCLR) degradation were investigated. Microcystis aeruginosa was exposed to four concentrations (0–5.0 mg Cu L−1) of three copper-Algaecide formulations, and rates and extents of MCLR degradation were measured. In untreated controls and following exposures of 0.1, 0.5, and 1.0 mg Cu L−1, MCLR concentrations decreased at a rate of ∼41–53 μg MCLR/L d−1. Following exposure to 5.0 mg Cu L−1 MCLR degradation rates decreased an order of magnitude to ∼3–7 μg MCLR/L d−1. Bacterial diversity decreased following copper-exposures greater than 0.1 mg Cu L−1 for all formulations. Relative abundance of certain groups of MC-degrading bacteria identified in treatments increased with increasing copper concentration, suggesting they may be less sensitive to copper exposures than other, MCLR and non MC-degrading heterotrophic bacteria present in the assemblage. Results from this study revealed that copper concentration can influence degradation rates of MCLR, however this influence was not significant within copper concentrations currently registered for use (≤1.0 mg Cu L−1) of the tested Algaecides. Copper formulation did not significantly alter degradation rates or bacterial composition. These data augment our understanding of the influences of copper Algaecide-exposures on MCLR degradation, and can be used to inform more accurate risk evaluations and use of copper-Algaecides for management of MCLR-producing cyanobacteria.

  • Predicting In Situ Responses of Taste- and Odor-Producing Algae in a Southeastern US Reservoir to a Sodium Carbonate Peroxyhydrate Algaecide Using a Laboratory Exposure-Response Model
    Water Air & Soil Pollution, 2017
    Co-Authors: Tyler D. Geer, Ciera M Kinley, Kyla J Iwinski, Alyssa J Calomeni, John H Rodgers
    Abstract:

    Efficacy of an in situ Algaecide treatment can be predicted prior to an application by physically modeling exposures and responses with laboratory experiments. A sodium carbonate peroxyhydrate (SCP) Algaecide was used in a drinking water reservoir (Hartwell Lake, Anderson, SC) to control a benthic algal assemblage putatively producing 2-methylisoboreol (MIB) and geosmin, compounds with adverse taste and odor attributes. These SCP applications provided an opportunity to test hypotheses regarding potential convergence of laboratory and in situ exposures and responses. Objectives of this study were to (1) measure responses of a benthic algal assemblage from Hartwell Lake to 7-day laboratory exposures of SCP [measured as hydrogen peroxide (H_2O_2) concentrations], (2) to measure the exposure of SCP (as H_2O_2) applied in a cove of Hartwell Lake and consequent responses of the algal assemblage, and (3) compare exposures and responses measured in the laboratory and in situ. Results demonstrated that in laboratory exposures, H_2O_2 released by SCP dissipated within 48 h. Significant responses of the algal assemblage in terms of phycocyanin concentrations and cell densities were measured 4 days after treatment (4-DAT) and 7-DAT following exposures of 453, 615, and 812 mg H_2O_2 m^−2. The H_2O_2 exposure measured in situ was comparable to effective laboratory exposures in terms of initial exposure (619 ± 428 mg H_2O_2 m^−2) and exposure duration (dissipation within 30 h), but the in situ exposure had a large deviation initially (i.e., ±428 mg H_2O_2 m^−2) and was an order of magnitude less than the targeted initial exposure. Therefore, comparison of measured responses was critical to infer comparable exposures and confirm accuracy of the laboratory model. Significant in situ responses were measured 4-DAT and 7-DAT in terms of phycocyanin concentrations and cell densities, and were comparable to responses obtained from effective laboratory exposures (i.e., 453, 615, and 812 mg H_2O_2 m^−2). Decreases in measured concentrations of MIB and geosmin at the intake of the drinking water treatment facility provided additional evidence that algae were sufficiently exposed to H_2O_2 from SCP. Results of this experiment provide evidence for the design and use of physical laboratory models to predict responses of algae in the field.

  • Analysis of Algaecide Exposures: an Evaluation of the I3− Method to Measure Sodium Carbonate Peroxyhydrate Algaecides
    Water Air & Soil Pollution, 2015
    Co-Authors: Ciera M Kinley, Andrew D Mcqueen, Kyla J Iwinski, John H Rodgers, Alyssa J Calomeni
    Abstract:

    Algaecides are commonly used to control noxious algal growths in water resources. In order to make accurate predictions about responses of target and non-target species to Algaecide exposures, reliable methods are needed to confirm exposures in the laboratory and the field. The focus of this research was to evaluate the I3 − method for measuring hydrogen peroxide (H2O2) exposures associated with applications of a sodium carbonate peroxyhydrate (SCP)-based Algaecide. To meet this overall objective, method detection limits, interferences from field waters (turbidity, color, and algal cell density), and storage stability of samples were measured. The method detection limits were 0.2 (p < 0.0001) and 0.25 mg H2O2/L (p = 0.0002) for laboratory and field waters, respectively. The upper method detection limit was 7.5 mg H2O2/L for both waters. Turbidity (25.3 NTU) and color of field-collected water did not interfere with measurements. Algal cell densities of 104, 105, and 106 cells/mL of two planktonic algal species in laboratory water did not interfere with measurements. Measurements of samples stored in dark refrigeration and on ice remained stable over 4 days, while measurements of samples stored in direct sunlight in ambient temperatures were altered after 1 day. The I3 − method accurately measured H2O2 exposures in the laboratory water, field water, and laboratory water containing planktonic algae used in this experiment within the range of concentrations that would be applied in a field setting. These data demonstrated that this method has utility for confirming exposures after laboratory and field treatments of SCP-based Algaecides.

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  • effects of different Algaecides on the photosynthetic capacity cell integrity and microcystin lr release of microcystis aeruginosa
    Science of The Total Environment, 2013
    Co-Authors: Shiqing Zhou, Yisheng Shao, Yang Deng, Junlian Qiao, Huase Ou, Jing Deng
    Abstract:

    Abstract Bench scale tests were conducted to study the effects of four common Algaecides, including copper sulfate, hydrogen peroxide, diuron and ethyl 2-methylacetoacetate (EMA) on the photosynthetic capacity, cell integrity and microcystin-LR (MC-LR) release of Microcystis aeruginosa . The release of potassium (K + ) from cell membrane during Algaecide exposure was also analyzed. The three typical photosynthetic parameters, including the effective quantum yield ( Ф e ), photosynthetic efficiency (α) and maximal electron transport rate (rETR max ), were measured by a pulse amplitude modulated (PAM) fluorometry. Results showed that the photosynthetic capacity was all inhibited by the four Algaecides, to different degrees, by limiting the energy capture in photosynthesis, and blocking the electron transfer chain in primary reaction. For example, at high diuron concentration (7.5 mg L − 1 ), Ф e , α and rETR max decreased from 0.46 to 0.19 ( p p − 2  s − 1 /μmol photons m − 2  s − 1 , and from 160.7 to 0.1 ( p − 2  s − 1 compared with the control group after 96 h of exposure, respectively. Furthermore, the increase of Algaecide dose could lead to the cell lysis, as well as release of intracellular MC-LR that enhanced the accumulation of extracellular MC-LR. The order of MC-LR release potential for the four Algaecides was CuSO 4  > H 2 O 2  > diuron > EMA.

  • Effects of different Algaecides on the photosynthetic capacity, cell integrity and microcystin-LR release of Microcystis aeruginosa.
    The Science of the total environment, 2013
    Co-Authors: Shiqing Zhou, Yisheng Shao, Naiyun Gao, Yang Deng, Junlian Qiao, Jing Deng
    Abstract:

    Bench scale tests were conducted to study the effects of four common Algaecides, including copper sulfate, hydrogen peroxide, diuron and ethyl 2-methylacetoacetate (EMA) on the photosynthetic capacity, cell integrity and microcystin-LR (MC-LR) release of Microcystis aeruginosa. The release of potassium (K(+)) from cell membrane during Algaecide exposure was also analyzed. The three typical photosynthetic parameters, including the effective quantum yield (Фe), photosynthetic efficiency (α) and maximal electron transport rate (rETRmax), were measured by a pulse amplitude modulated (PAM) fluorometry. Results showed that the photosynthetic capacity was all inhibited by the four Algaecides, to different degrees, by limiting the energy capture in photosynthesis, and blocking the electron transfer chain in primary reaction. For example, at high diuron concentration (7.5 mg L(-1)), Фe, α and rETRmax decreased from 0.46 to 0.19 (pEMA.