1
|
Castilla-Alcantara JC, Ghoshal S, Ortega-Calvo JJ. Taxis-enhanced mineralization and co-metabolism of PAHs by bacteria in micrometer-scale environments. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 951:175520. [PMID: 39147064 DOI: 10.1016/j.scitotenv.2024.175520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2024] [Revised: 08/07/2024] [Accepted: 08/12/2024] [Indexed: 08/17/2024]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are associated with micropores in sediments and soils. This limits the bioaccessibility of these compounds via existing bioremediation technologies, as biodegradation is strongly influenced by the ability of bacteria to access different sizes of pores. In this work, we employed naphthalene and pyrene as model contaminants to evaluate the transformation capacity of the soil bacterium Pseudomonas putida G7 (2 × 1 μm) via mineralization and co-metabolic activity, respectively. Under non-growing conditions and in the absence of hydraulic flow, we examined how the tactic behavior of this motile bacterium influenced biodegradation of these two PAHs when passing through membranes with micrometer-sized pores (3 and 5 μm). The bacteria were spontaneously retained by the membranes, which blocked the contaminants away from a passive dosing source. However, the cells were mobilized through 5 μm pores after the application plant root exudate components (γ-aminobutyric acid, citrate and fructose) as strong chemoeffectors, which enhanced the mineralization of naphthalene and co-metabolism of pyrene. The tactic-mediated biodegradation enhancement did not occur through 3 μm pores, possibly due a physical constrain to the gradient sensing mechanism. Our results suggest that bacterial transport by chemotaxis may enhance the biotransformation of poorly bioaccessible contaminants present in micro-meter scale environments.
Collapse
Affiliation(s)
| | - Subhasis Ghoshal
- Department of Civil Engineering, McGill University, Montreal, Quebec H3A 0C3, Canada
| | - Jose Julio Ortega-Calvo
- Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS-CSIC), Avda. Reina Mercedes 10, E-41012 Seville, Spain.
| |
Collapse
|
2
|
Lopez Gordillo AP, Trueba-Santiso A, Lema JM, Schäffer A, Smith KEC. Sulfamethoxazole is Metabolized and Mineralized at Extremely Low Concentrations. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:9723-9730. [PMID: 38761139 PMCID: PMC11155234 DOI: 10.1021/acs.est.4c02191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 05/07/2024] [Accepted: 05/08/2024] [Indexed: 05/20/2024]
Abstract
The presence of organic micropollutants in water and sediments motivates investigation of their biotransformation at environmentally low concentrations, usually in the range of μg L-1. Many are biotransformed by cometabolic mechanisms; however, there is scarce information concerning their direct metabolization in this concentration range. Threshold concentrations for microbial assimilation have been reported in both pure and mixed cultures from different origins. The literature suggests a range value for bacterial growth of 1-100 μg L-1 for isolated aerobic heterotrophs in the presence of a single substrate. We aimed to investigate, as a model case, the threshold level for sulfamethoxazole (SMX) metabolization in pure cultures of Microbacterium strain BR1. Previous research with this strain has covered the milligram L-1 range. In this study, acclimated cultures were exposed to concentrations from 0.1 to 25 μg L-1 of 14C-labeled SMX, and the 14C-CO2 produced was trapped and quantified over 24 h. Interestingly, SMX removal was rapid, with 98% removed within 2 h. In contrast, mineralization was slower, with a consistent percentage of 60.0 ± 0.7% found at all concentrations. Mineralization rates increased with rising concentrations. Therefore, this study shows that bacteria are capable of the direct metabolization of organic micropollutants at extremely low concentrations (sub μg L-1).
Collapse
Affiliation(s)
- Ana P. Lopez Gordillo
- Institute
for Environmental Research, RWTH Aachen
University, Worringerweg 1, 52074 Aachen, Germany
- CRETUS,
Department of Chemical Engineering, Universidade
de Santiago de Compostela, 15782 Santiago de Compostela, Galicia Spain
| | - Alba Trueba-Santiso
- CRETUS,
Department of Chemical Engineering, Universidade
de Santiago de Compostela, 15782 Santiago de Compostela, Galicia Spain
| | - Juan M. Lema
- CRETUS,
Department of Chemical Engineering, Universidade
de Santiago de Compostela, 15782 Santiago de Compostela, Galicia Spain
| | - Andreas Schäffer
- Institute
for Environmental Research, RWTH Aachen
University, Worringerweg 1, 52074 Aachen, Germany
| | - Kilian E. C. Smith
- Environmental
Chemistry, Magdeburg-Stendal University
of Applied Sciences, Breitscheidstraße 2, Building 6, 39114 Magdeburg, Germany
| |
Collapse
|
3
|
Hu H, Ma P, Li H, You J. Determining buffering capacity of polydimethylsiloxane-based passive dosing for hydrophobic organic compounds in large-volume bioassays. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 914:169710. [PMID: 38184249 DOI: 10.1016/j.scitotenv.2023.169710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 12/25/2023] [Accepted: 12/25/2023] [Indexed: 01/08/2024]
Abstract
Polydimethylsiloxane (PDMS) is the most widely used material for passive dosing. However, the ability of PDMS to maintain constant water concentrations of chemicals in large-volume bioassays was insufficiently investigated. In this study, we proposed a kinetic-based method to determine the buffering capacity of PDMS for maintaining constant water concentrations of hydrophobic organic contaminants (HOCs) in large-volume bioassays. A good correlation between log Kow and PDMS-water partitioning coefficients (log KPW) was observed for HOCs with log Kow values ranging from 3.30 to 7.42. For low-molecular-weight HOCs, volatile loss was identified as the primary cause of unstable water concentrations in passive dosing systems. Slow desorption from PDMS resulted in a reduction of water concentrations for high-molecular-weight HOCs. The volume ratio of PDMS to water (RV) was the key factor controlling buffering capacity. As such, buffering capacity was defined as the minimum RV required to maintain 90% of the initial water concentration and was determined to be 0.0076-0.032 for six representative HOCs. Finally, passive dosing with an RV of 0.014 was validated to effectively maintain water concentrations of phenanthrene in 2-L and 96-h toxicity tests with adult mosquitofish. By determining buffering capacity of PDMS, this study recommended specific RV values for cost-efficient implementation of passive dosing approaches in aquatic toxicology, particularly in large-volume bioassays.
Collapse
Affiliation(s)
- Hao Hu
- Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou 511443, China
| | - Ping Ma
- Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou 511443, China; Department of Eco-engineering, Guangdong Eco-Engineering Polytechnic, Guangzhou 510520, China
| | - Huizhen Li
- Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou 511443, China.
| | - Jing You
- Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou 511443, China
| |
Collapse
|
4
|
Castilla-Alcantara JC, Posada-Baquero R, Ortega-Calvo JJ. Taxis-mediated bacterial transport and its implication for the cometabolism of pyrene in a model aquifer. WATER RESEARCH 2024; 248:120850. [PMID: 37976951 DOI: 10.1016/j.watres.2023.120850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 09/28/2023] [Accepted: 11/07/2023] [Indexed: 11/19/2023]
Abstract
One of the main problems in contaminated soils is that many toxic substances, such as PAHs, which are found in areas close to aquifers and groundwater, are difficult to access and degrade via traditional methods of remediation. The use of controlled bacterial mobility through chemotaxis has been shown to be efficient in increasing the dispersion of pollutant-degrading organisms, increasing the biodegradation rates of pollutants. In this study, using percolation columns as model aquifers, the mobilization of the Pseudomonas putida G7 strain to a distant pyrene source was demonstrated using γ-aminobutyric acid and artificial root exudates as strong chemoeffectors. An increase in the biodegradation rates of the pollutant was observed relative to columns in which the tactic effector was not added. The presence of different metabolites was detected via a fraction collector associated with an HPLC system, providing evidence for the cometabolic capacity of strain G7. The use of chemotactic organisms can be an effective approach for the remediation of polluted sediments associated with aquifers and groundwaters, offering new possibilities for the treatment of contaminated aqueous areas.
Collapse
Affiliation(s)
- Jose Carlos Castilla-Alcantara
- Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS-CSIC), Avda. Reina Mercedes 10, E-41012, Seville, Spain
| | - Rosa Posada-Baquero
- Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS-CSIC), Avda. Reina Mercedes 10, E-41012, Seville, Spain
| | - Jose Julio Ortega-Calvo
- Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS-CSIC), Avda. Reina Mercedes 10, E-41012, Seville, Spain.
| |
Collapse
|
5
|
Stoichev T, Mucha AP, Bernabeu A, Almeida CMR. Buried and surface oil degradation - Evaluating bioremediation to increase PAHs removal through linear mathematical models. MARINE POLLUTION BULLETIN 2023; 189:114727. [PMID: 36807045 DOI: 10.1016/j.marpolbul.2023.114727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 02/07/2023] [Accepted: 02/09/2023] [Indexed: 06/18/2023]
Abstract
A bioremediation approach with tide simulation for buried and surface oil degradation was tested for removal of two, three and four rings polycyclic aromatic hydrocarbons (PAHs). Linear models depicted degradation constants of individual PAH as simple additive function of their initial concentrations (C0) in contaminated sand, hydrophobicity, sampling layer and treatment conditions. For all PAHs and treatment conditions, the degradation of oil in buried layers was faster than at the surface. Naturally-occurring microorganisms proved to be efficient for bioremediation of PAHs and were stimulated by fertilizer addition (biostimulation, BS). Bioaugmentation (BA) by addition of a slurry of a native oil-degraders pre-stimulated consortium did not show faster PAH degradation than BS. Degradation was more rapid for PAH present at low C0 and with intermediate hydrophobicity. Bioremediation of beach sand either with surface or buried crude oil is a cost-effective strategy to clean-up different hydrocarbon families, including persistent ones, such as PAHs.
Collapse
Affiliation(s)
- Teodor Stoichev
- CIIMAR - Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Terminal de Cruzeiros do Porto de Leixões, Avenida General Norton de Matos, s/n, 4450-208 Matosinhos, Portugal
| | - Ana P Mucha
- CIIMAR - Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Terminal de Cruzeiros do Porto de Leixões, Avenida General Norton de Matos, s/n, 4450-208 Matosinhos, Portugal; Department of Chemistry and Biochemistry, Faculty of Sciences University of Porto, Rua do Campo Alegre 790, 4150-171 Porto, Portugal
| | - Ana Bernabeu
- Centro de Investigación Mariña, Universidade de Vigo, GEOMA, 36310 Vigo, Spain
| | - C Marisa R Almeida
- CIIMAR - Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Terminal de Cruzeiros do Porto de Leixões, Avenida General Norton de Matos, s/n, 4450-208 Matosinhos, Portugal; Department of Chemistry and Biochemistry, Faculty of Sciences University of Porto, Rua do Campo Alegre 790, 4150-171 Porto, Portugal.
| |
Collapse
|
6
|
Davenport R, Curtis‐Jackson P, Dalkmann P, Davies J, Fenner K, Hand L, McDonough K, Ott A, Ortega‐Calvo JJ, Parsons JR, Schäffer A, Sweetlove C, Trapp S, Wang N, Redman A. Scientific concepts and methods for moving persistence assessments into the 21st century. INTEGRATED ENVIRONMENTAL ASSESSMENT AND MANAGEMENT 2022; 18:1454-1487. [PMID: 34989108 PMCID: PMC9790601 DOI: 10.1002/ieam.4575] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 09/29/2021] [Accepted: 12/06/2021] [Indexed: 05/19/2023]
Abstract
The evaluation of a chemical substance's persistence is key to understanding its environmental fate, exposure concentration, and, ultimately, environmental risk. Traditional biodegradation test methods were developed many years ago for soluble, nonvolatile, single-constituent test substances, which do not represent the wide range of manufactured chemical substances. In addition, the Organisation for Economic Co-operation and Development (OECD) screening and simulation test methods do not fully reflect the environmental conditions into which substances are released and, therefore, estimates of chemical degradation half-lives can be very uncertain and may misrepresent real environmental processes. In this paper, we address the challenges and limitations facing current test methods and the scientific advances that are helping to both understand and provide solutions to them. Some of these advancements include the following: (1) robust methods that provide a deeper understanding of microbial composition, diversity, and abundance to ensure consistency and/or interpret variability between tests; (2) benchmarking tools and reference substances that aid in persistence evaluations through comparison against substances with well-quantified degradation profiles; (3) analytical methods that allow quantification for parent and metabolites at environmentally relevant concentrations, and inform on test substance bioavailability, biochemical pathways, rates of primary versus overall degradation, and rates of metabolite formation and decay; (4) modeling tools that predict the likelihood of microbial biotransformation, as well as biochemical pathways; and (5) modeling approaches that allow for derivation of more generally applicable biotransformation rate constants, by accounting for physical and/or chemical processes and test system design when evaluating test data. We also identify that, while such advancements could improve the certainty and accuracy of persistence assessments, the mechanisms and processes by which they are translated into regulatory practice and development of new OECD test guidelines need improving and accelerating. Where uncertainty remains, holistic weight of evidence approaches may be required to accurately assess the persistence of chemicals. Integr Environ Assess Manag 2022;18:1454-1487. © 2022 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).
Collapse
Affiliation(s)
| | | | - Philipp Dalkmann
- Bayer AG, Crop Science Division, Environmental SafetyMonheimGermany
| | | | - Kathrin Fenner
- Eawag, Swiss Federal Institute of Aquatic Science and TechnologyDübendorfSwitzerland
- Department of ChemistryUniversity of ZürichZürichSwitzerland
| | - Laurence Hand
- Syngenta, Product Safety, Jealott's Hill International Research CentreBracknellUK
| | | | - Amelie Ott
- School of EngineeringNewcastle UniversityNewcastle upon TyneUK
- European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC)BrusselsBelgium
| | - Jose Julio Ortega‐Calvo
- Instituto de Recursos Naturales y Agrobiología de SevillaConsejo Superior de Investigaciones CientíficasSevillaSpain
| | - John R. Parsons
- Institute for Biodiversity and Ecosystem DynamicsUniversity of AmsterdamAmsterdamThe Netherlands
| | - Andreas Schäffer
- RWTH Aachen University, Institute for Environmental ResearchAachenGermany
| | - Cyril Sweetlove
- L'Oréal Research & InnovationEnvironmental Research DepartmentAulnay‐sous‐BoisFrance
| | - Stefan Trapp
- Department of Environmental EngineeringTechnical University of DenmarkBygningstorvetLyngbyDenmark
| | - Neil Wang
- Total Marketing & ServicesParis la DéfenseFrance
| | - Aaron Redman
- ExxonMobil Petroleum and ChemicalMachelenBelgium
| |
Collapse
|
7
|
Kreutzer A, Faetsch S, Heise S, Hollert H, Witt G. Passive dosing: Assessing the toxicity of individual PAHs and recreated mixtures to the microalgae Raphidocelis subcapitata. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2022; 249:106220. [PMID: 35777163 DOI: 10.1016/j.aquatox.2022.106220] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 05/06/2022] [Accepted: 06/09/2022] [Indexed: 06/15/2023]
Abstract
Risk assessment of hydrophobic organic compounds (HOCs) is difficult because maintaining a well-defined exposure during aquatic toxicity testing is challenging due to the limited water solubility and various loss processes such as volatilization, biodegradation and sorption. Passive dosing techniques help to overcome these challenges by providing a well-controlled and solvent-free exposure. In this study, the algal growth inhibition test (DIN EN ISO 8692) was converted into a miniaturized passive dosing setting. For this purpose, biocompatible O-rings were used as substance reservoirs and loaded with polycyclic aromatic hydrocarbons (PAHs). The growth inhibition of the microalgae Raphidocelis subcapitata induced by single PAHs (log KOW 3.24-5.91) was investigated. In addition, recreated PAH mixtures were tested representing field compositions of the pore water North Sea sediments. Some of the single PAHs revealed strong growth inhibiting effects on the algal growth, while the recreated mixture compositions had slightly lower effect on the growth inhibition in the highest concentrations. Overall, the toxicity of the PAHs generally increased with the maximum chemical activities (amax) of the PAHs and the inhibition data could be fitted with one maximum chemical activity response curve. Therefore, the miniaturized passive dosing approach appears as a promising practical and economical method that can be used for toxicity testing of the different trophic levels to improve comprehensive risk assessment.
Collapse
Affiliation(s)
- Anne Kreutzer
- Department Evolutionary Ecology and Environmental Toxicology, Institute of Ecology, Evolution and Diversity, Faculty Biological Sciences, Goethe University Frankfurt, Frankfurt 60438, Germany; Department of Environmental Engineering, Faculty Life Sciences, Hamburg University of Applied Sciences, Hamburg 21033, Germany
| | - Sonja Faetsch
- Department of Biomedical Engineering, Faculty Life Sciences, Hamburg University of Applied Sciences, Hamburg 21033, Germany
| | - Susanne Heise
- Department of Biomedical Engineering, Faculty Life Sciences, Hamburg University of Applied Sciences, Hamburg 21033, Germany
| | - Henner Hollert
- Department Evolutionary Ecology and Environmental Toxicology, Institute of Ecology, Evolution and Diversity, Faculty Biological Sciences, Goethe University Frankfurt, Frankfurt 60438, Germany
| | - Gesine Witt
- Department of Environmental Engineering, Faculty Life Sciences, Hamburg University of Applied Sciences, Hamburg 21033, Germany.
| |
Collapse
|
8
|
Birch H, Sjøholm KK, Dechesne A, Sparham C, van Egmond R, Mayer P. Biodegradation Kinetics of Fragrances, Plasticizers, UV Filters, and PAHs in a Mixture─Changing Test Concentrations over 5 Orders of Magnitude. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:293-301. [PMID: 34936331 DOI: 10.1021/acs.est.1c05583] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Biodegradation of organic chemicals emitted to the environment is carried out by mixed microbial communities growing on multiple natural and xenobiotic substrates at low concentrations. This study aims to (1) perform simulation type biodegradation tests at a wide range of mixture concentrations, (2) determine the concentration effect on the biodegradation kinetics of individual chemicals, and (3) link the mixture concentration and degradation to microbial community dynamics. Two hundred ninety-four parallel test systems were prepared using wastewater treatment plant effluent as inoculum and passive dosing to add a mixture of 19 chemicals at 6 initial concentration levels (ng/L to mg/L). After 1-30 days of incubation at 12 °C, abiotic and biotic test systems were analyzed using arrow solid phase microextraction and GC-MS/MS. Biodegradation kinetics at the highest test concentrations were delayed for several test substances but enhanced for the reference chemical naphthalene. Test concentration thus shifted the order in which chemicals were degraded. 16S rRNA gene amplicon sequencing indicated that the highest test concentration (17 mg C/L added) supported the growth of the genera Acidovorax, Novosphingobium, and Hydrogenophaga, whereas no such effect was observed at lower concentrations. The chemical and microbial results confirm that too high mixture concentrations should be avoided when aiming at determining environmentally relevant biodegradation data.
Collapse
Affiliation(s)
- Heidi Birch
- Department of Environmental Engineering, Technical University of Denmark, Bygningstorvet, Building 115, 2800 Kgs. Lyngby, Denmark
| | - Karina Knudsmark Sjøholm
- Department of Environmental Engineering, Technical University of Denmark, Bygningstorvet, Building 115, 2800 Kgs. Lyngby, Denmark
| | - Arnaud Dechesne
- Department of Environmental Engineering, Technical University of Denmark, Bygningstorvet, Building 115, 2800 Kgs. Lyngby, Denmark
| | - Chris Sparham
- Safety & Environmental Assurance Centre, Unilever, Bedford MK44 1LQ, U.K
| | - Roger van Egmond
- Safety & Environmental Assurance Centre, Unilever, Bedford MK44 1LQ, U.K
| | - Philipp Mayer
- Department of Environmental Engineering, Technical University of Denmark, Bygningstorvet, Building 115, 2800 Kgs. Lyngby, Denmark
| |
Collapse
|
9
|
Godéré M, Malleret L, Höhener P, Doumenq P. Passive sampling of chlorinated paraffins by silicone: Focus on diffusion and silicone-water partition coefficients. CHEMOSPHERE 2022; 287:132201. [PMID: 34509757 DOI: 10.1016/j.chemosphere.2021.132201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 09/02/2021] [Accepted: 09/06/2021] [Indexed: 06/13/2023]
Abstract
Short-chain chlorinated paraffins (SCCPs) are under regulation through the European Water Framework Directive and were recently classified as POPs. Consecutively, the increasing use of middle-chain chlorinated paraffins (MCCPs) becomes of growing concern. Knowledge on the occurrence of chlorinated paraffins (CPs) is still scarce particularly in water phase. To achieve sufficient method sensitivity, the passive sampling approach, acting as a relevant alternative to usual grab sampling, has been considered only very recently for the monitoring of CPs in water. The present work aimed at determining the diffusion coefficients in silicone (Ds) and the silicone-water partition coefficients (Ksw) of various CP groups, having different chlorine contents and carbon chain lengths, in four commercial CP mixtures. Log Ds (-10.78 to -10.21) was found to vary little and to be high for the groups of CPs studied. Thus, their uptake in silicone is controlled by the water boundary layer, which allows to consider the release of performance and reference compounds for in-field estimation of the sampling rate. Moreover, CPs partitioned strongly towards silicone rubbers. Both the chlorination degree and the carbon chain length of CPs cause large uncertainties in the partitioning between silicone and water (log Ksw between 4.85 and 6.30), indicating that instead of an average value, differentiated Ksw should be used to estimate aqueous CPs more accurately. Even so, the probable influence of chlorine atoms position on polarity and partitioning may be an argument for favoring sampling in the kinetic stage.
Collapse
Affiliation(s)
- Mathilde Godéré
- Aix Marseille Université, CNRS, Laboratoire Chimie Environnement, France
| | - Laure Malleret
- Aix Marseille Université, CNRS, Laboratoire Chimie Environnement, France.
| | - Patrick Höhener
- Aix Marseille Université, CNRS, Laboratoire Chimie Environnement, France
| | - Pierre Doumenq
- Aix Marseille Université, CNRS, Laboratoire Chimie Environnement, France
| |
Collapse
|
10
|
Knudsmark Sjøholm K, Birch H, Hammershøj R, Saunders DMV, Dechesne A, Loibner AP, Mayer P. Determining the Temperature Dependency of Biodegradation Kinetics for 34 Hydrocarbons while Avoiding Chemical and Microbial Confounding Factors. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:11091-11101. [PMID: 34355887 DOI: 10.1021/acs.est.1c02773] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Biodegradation kinetics data are keystone for evaluating the environmental persistence and risk of chemicals. Biodegradation kinetics depend highly on the prevailing temperature, which influences microbial community structures, metabolic rates, and chemical availability. There is a lack of high-quality comparative biodegradation kinetics data that are determined at different test temperatures but with the same microbial inoculum and chemical availability. The present study was designed to determine the effect of test temperature on the biodegradation kinetics of hydrocarbons while avoiding confounding factors. We used inocula from a Northern river (2.7 °C) and a Central European river (12.5 °C). Aqueous stock solutions containing 45 individual hydrocarbons were generated by passive dosing and added to river water containing the native microorganisms. Compound-specific biodegradation kinetics were then determined at 2.7, 12, and 20 °C based on substrate depletion. Main findings comprise the following: (1) Degradation half-times (DegT50) of 34 test chemicals were determined at different test temperatures and were largely consistent with the Arrhenius equation (activation energy, 65.4 kJ/mol). (2) Differences in biodegradation kinetics between tested isomers were rather limited. (3) The recent lowering of standard test temperature from 20 to 12 °C results typically in a doubling of DegT50 values and can lead to a stricter persistency assessment.
Collapse
Affiliation(s)
- Karina Knudsmark Sjøholm
- Department of Environmental Engineering, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
| | - Heidi Birch
- Department of Environmental Engineering, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
| | - Rikke Hammershøj
- Department of Environmental Engineering, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
| | - David M V Saunders
- Shell Health, Shell International B.V., 2596 HR The Hague, The Netherlands
| | - Arnaud Dechesne
- Department of Environmental Engineering, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
| | - Andreas P Loibner
- Institute of Environmental Biotechnology, BOKU - University of Natural Resources and Life Sciences, Vienna, A-3430 Tulln, Austria
| | - Philipp Mayer
- Department of Environmental Engineering, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
| |
Collapse
|
11
|
|
12
|
Fernández-López C, Posada-Baquero R, García JL, Castilla-Alcantara JC, Cantos M, Ortega-Calvo JJ. Root-mediated bacterial accessibility and cometabolism of pyrene in soil. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 760:143408. [PMID: 33243519 DOI: 10.1016/j.scitotenv.2020.143408] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 10/19/2020] [Accepted: 10/19/2020] [Indexed: 06/11/2023]
Abstract
Partial transformation of pollutants and mobilization of the produced metabolites may contribute significantly to the risks resulting from biological treatment of soils polluted by hydrophobic chemicals such as polycyclic aromatic hydrocarbons (PAHs). Pyrene, a four-ringed PAH, was selected here as a model pollutant to study the effects of sunflower plants on the bacterial accessibility and cometabolism of this pollutant when located at a spatially distant source within soil. We compared the transformation of passively dosed 14C-labeled pyrene in soil slurries and planted pots that were inoculated with the bacterium Pseudomonas putida G7. This bacterium combines flagellar cell motility with the ability to cometabolically transform pyrene. Cometabolism of this PAH occurred immediately in the inoculated and shaken soil slurries, where the bacteria had full access to the passive dosing devices (silicone O-rings). Root exudates did not enhance the survival of P. putida G7 cells in soil slurries, but doubled their transport in column tests. In greenhouse-incubated soil pots with the same pyrene sources instead located centimeters from the soil surface, the inoculated bacteria transformed 14C-labeled pyrene only when the pots were planted with sunflowers. Bacterial inoculation caused mobilization of 14C-labeled pyrene metabolites into the leachates of the planted pots at concentrations of approximately 1 mg L-1, ten times greater than the water solubility of the parent compound. This mobilization resulted in a doubled specific root uptake rate of 14C-labeled pyrene equivalents and a significantly decreased root-to-fruit transfer rate. Our results show that the plants facilitated bacterial access to the distant pollutant source, possibly by increasing bacterial dispersal in the soil; this increased bacterial access was associated with cometabolism, which contributed to the risks of biodegradation.
Collapse
Affiliation(s)
- Carmen Fernández-López
- University Centre of Defense at the Spanish Air Force Academy, Santiago de la Ribera, Spain
| | - Rosa Posada-Baquero
- Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS-CSIC), Seville, Spain
| | - José Luis García
- Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS-CSIC), Seville, Spain
| | | | - Manuel Cantos
- Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS-CSIC), Seville, Spain
| | | |
Collapse
|
13
|
Hammershøj R, Sjøholm KK, Birch H, Brandt KK, Mayer P. Biodegradation kinetics testing of two hydrophobic UVCBs - potential for substrate toxicity supports testing at low concentrations. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2020; 22:2172-2180. [PMID: 33000828 DOI: 10.1039/d0em00288g] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The biodegradation kinetics of UVCB substances (unknown or variable composition, complex reaction products or biological materials) should be determined below the solubility limit to avoid experimental artefacts by the non-dissolved mixture. Recently, we reported delayed biodegradation kinetics of single petroleum hydrocarbons even at concentrations just below the solubility limit and attributed this to toxicity. The present study aimed to determine the concentration effect on biodegradation kinetics for constituents in two UVCBs, using surface water from a rural stream as the inoculum. Parallel biodegradation tests of diesel and lavender oil were conducted at concentrations just below the solubility limit and two orders of magnitude lower. The biodegradation kinetics of diesel oil constituents were generally similar at the two concentrations, which coincided with the stimulation of bacterial productivity (growth) at both concentrations, determined by [3H]leucine incorporation. By contrast, the biodegradation of lavender oil constituents was significantly delayed or even halted at the high test concentration. This was consistent with lavender oil stimulating bacterial growth at low concentration but inhibiting it at high concentration. The delayed biodegradation kinetics of lavender oil constituents at high concentration was best explained by mixture toxicity near the solubility limit. Consequently, biodegradation testing of hydrophobic UVCBs should be conducted at low, environmentally relevant concentrations ensuring that mixture toxicity does not affect the biodegradation kinetics.
Collapse
Affiliation(s)
- Rikke Hammershøj
- Technical University of Denmark, Department of Environmental Engineering, Bygningstorvet, Building 115, 2800 Kgs. Lyngby, Denmark.
| | - Karina K Sjøholm
- Technical University of Denmark, Department of Environmental Engineering, Bygningstorvet, Building 115, 2800 Kgs. Lyngby, Denmark.
| | - Heidi Birch
- Technical University of Denmark, Department of Environmental Engineering, Bygningstorvet, Building 115, 2800 Kgs. Lyngby, Denmark.
| | - Kristian K Brandt
- University of Copenhagen, Department of Plant and Environmental Sciences, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark
| | - Philipp Mayer
- Technical University of Denmark, Department of Environmental Engineering, Bygningstorvet, Building 115, 2800 Kgs. Lyngby, Denmark.
| |
Collapse
|
14
|
Lee SY, Kwon JH. Enhancement of Toxic Efficacy of Alkylated Polycyclic Aromatic Hydrocarbons Transformed by Sphingobium quisquiliarum. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17176416. [PMID: 32899285 PMCID: PMC7503419 DOI: 10.3390/ijerph17176416] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 08/28/2020] [Accepted: 09/01/2020] [Indexed: 11/16/2022]
Abstract
Alkylated polycyclic aromatic hydrocarbons (PAHs) are abundant in crude oils and refined petroleum products and are considered as major contributors to the toxicity of spilled oils. In this study, the microbial degradation of model (alkylated) PAHs (i.e., phenanthrene, 3-methylphenanthrene, 3,6-dimethylphenanthrene (36DMPhe), pyrene, and 1-methylpyrene (1MP)) by the bacterium Sphingobium quisquiliarum EPA505, a known degrader of PAHs, was studied. To evaluate the toxic potential of the metabolic products, reaction mixtures containing metabolites of 36DMPhe and 1MP were fractionated by high-performance liquid chromatography, and their effects on the luminescence inhibition of Aliivibrio fischeri were evaluated. Although the luminescence inhibition of 36DMPhe and 1MP at their solubility levels was not observed, inhibition was observed in their metabolite fractions at the solubility limit of their parent molecule. This indicates that initial biotransformation increases the toxicity of alkylated PAHs because of the increased solubility and/or inherent toxicity of metabolites. Qualitative analysis of the metabolite fractions suggested that mono-oxidation of the methyl group is the main metabolic pathway of 36DMPhe and 1MP.
Collapse
|
15
|
Stibany F, Schmidt SN, Mayer P, Schäffer A. Toxicity of dodecylbenzene to algae, crustacean, and fish - Passive dosing of highly hydrophobic liquids at the solubility limit. CHEMOSPHERE 2020; 251:126396. [PMID: 32163782 DOI: 10.1016/j.chemosphere.2020.126396] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 02/28/2020] [Accepted: 02/29/2020] [Indexed: 06/10/2023]
Abstract
In the current study, improved exposure control and measurements were applied for the aquatic toxicity testing of a highly hydrophobic organic compound. The aim was to reliably determine the ecotoxicity of the model compound dodecylbenzene (DDB, Log KOW = 8.65) by applying passive dosing for aquatic toxicity testing exactly at the solubility limit. Methodologically, silicone O-rings were saturated by immersion in pure liquid DDB (i.e., "loading by swelling") and then used as passive dosing donors. Daphnia immobilization and fish embryo toxicity tests were successfully conducted and provide, together with recently reported algal growth inhibition data, a full base-set of ecotoxicological data according to REACH. All tests were conducted in closed test systems to avoid evaporative losses, and exposure concentrations were measured throughout test durations. The Daphnia test was optimized by placing the O-rings in cages to prevent direct contact between daphnids and the passive dosing donor. Toxicologically, Daphnia magna immobilization was 19.3 ± 8% (mean ± 95% CI; 6 tests) within 72 h, whereas Danio rerio fish embryos did not show any significant lethal or sublethal toxic responses within 96 h. Growth rate inhibition for the algae Raphidocelis subcapitata was previously reported to be 13 ± 5% in a first and 8 ± 3% in a repeated test. These results for aquatic organisms, spanning three trophic levels, demonstrate toxicity of a highly hydrophobic compound and suggest that improvements of the current ecotoxicological standard tests are needed for these "difficult-to-test" chemicals. Furthermore, the obtained toxicity results significantly question the existence of a generic Log KOW cut-off in baseline toxicity.
Collapse
Affiliation(s)
- Felix Stibany
- Institute for Environmental Research (Biology V), RWTH Aachen University, Worringerweg 1, 52074, Aachen, Germany; Department of Environmental Engineering, Technical University of Denmark, Bygningstorvet B115, 2800, Kgs. Lyngby, Denmark.
| | - Stine Nørgaard Schmidt
- Department of Environmental Engineering, Technical University of Denmark, Bygningstorvet B115, 2800, Kgs. Lyngby, Denmark
| | - Philipp Mayer
- Department of Environmental Engineering, Technical University of Denmark, Bygningstorvet B115, 2800, Kgs. Lyngby, Denmark
| | - Andreas Schäffer
- Institute for Environmental Research (Biology V), RWTH Aachen University, Worringerweg 1, 52074, Aachen, Germany
| |
Collapse
|
16
|
Rolando L, Vila J, Baquero RP, Castilla-Alcantara JC, Barra Caracciolo A, Ortega-Calvo JJ. Impact of bacterial motility on biosorption and cometabolism of pyrene in a porous medium. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 717:137210. [PMID: 32062235 DOI: 10.1016/j.scitotenv.2020.137210] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 02/07/2020] [Accepted: 02/07/2020] [Indexed: 06/10/2023]
Abstract
The risks of pollution by polycyclic aromatic hydrocarbons (PAHs) may increase in bioremediated soils as a result of the formation of toxic byproducts and the mobilization of pollutants associated to suspended colloids. In this study, we used the motile and chemotactic bacterium Pseudomonas putida G7 as an experimental model for examining the potential role of bacterial motility in the cometabolism and biosorption of pyrene in a porous medium. For this purpose, we conducted batch and column transport experiments with 14C-labelled pyrene loaded on silicone O-rings, which acted as a passive dosing system. In the batch experiments, we observed concentrations of the 14C-pyrene equivalents well above the equilibrium concentration observed in abiotic controls. This mobilization was attributed to biosorption and cometabolism processes occurring in parallel. HPLC quantification revealed pyrene concentrations well below the 14C-based quantifications by liquid scintillation, indicating pyrene transformation into water-soluble polar metabolites. The results from transport experiments in sand columns revealed that cometabolic-active, motile cells were capable of accessing a distant source of sorbed pyrene. Using the same experimental system, we also determined that salicylate-mobilized cells, inhibited for pyrene cometabolism, but mobilized due to their tactic behavior, were able to sorb the compound and mobilize it by biosorption. Our results indicate that motile bacteria active in bioremediation may contribute, through cometabolism and biosorption, to the risk associated to pollutant mobilization in soils. This research could be the starting point for the development of more efficient, low-risk bioremediation strategies of poorly bioavailable contaminants in soils.
Collapse
Affiliation(s)
- Ludovica Rolando
- Istituto di Ricerca Sulle Acque (IRSA), CNR, Via Salaria km 29.300, 00015 Monterotondo Scalo, RM, Italy; Dipartimento di Science Ecologiche e Biologiche (DEB), Universita degli studi della Tuscia, Via San Camillo de Lellis, 01100 Viterbo, Italy; Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS), CSIC, Avenida Reina Mercedes, 10, E-41012 Seville, Spain
| | - Joaquim Vila
- Departament de Microbiologia, Universitat de Barcelona, Avenida Diagonal 643, 08028 Barcelona, Spain; Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS), CSIC, Avenida Reina Mercedes, 10, E-41012 Seville, Spain
| | - Rosa Posada Baquero
- Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS), CSIC, Avenida Reina Mercedes, 10, E-41012 Seville, Spain
| | - Jose Carlos Castilla-Alcantara
- Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS), CSIC, Avenida Reina Mercedes, 10, E-41012 Seville, Spain
| | - Anna Barra Caracciolo
- Istituto di Ricerca Sulle Acque (IRSA), CNR, Via Salaria km 29.300, 00015 Monterotondo Scalo, RM, Italy
| | - Jose-Julio Ortega-Calvo
- Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS), CSIC, Avenida Reina Mercedes, 10, E-41012 Seville, Spain.
| |
Collapse
|
17
|
Hammershøj R, Birch H, Sjøholm KK, Mayer P. Accelerated Passive Dosing of Hydrophobic Complex Mixtures-Controlling the Level and Composition in Aquatic Tests. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:4974-4983. [PMID: 32142613 DOI: 10.1021/acs.est.9b06062] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Petroleum products and essential oils are complex mixtures of hydrophobic and volatile chemicals and are categorized as substances of unknown or variable composition, complex reaction products, or biological materials (UVCBs). In aquatic testing and research of such mixtures, it is challenging to establish initial concentrations without the addition of cosolvents, to maintain constant concentrations during the test, and to keep a constant mixture composition in dilution series and throughout test duration. Passive dosing was here designed to meet these challenges by maximizing the surface area (Adonor/Vmedium = 3.8 cm2/mL) and volume (Vdonor/Vmedium > 0.1 L/L) of the passive dosing donor in order to ensure rapid mass transfer and avoid donor depletion for all mixture constituents. Cracked gas oil, cedarwood Virginia oil, and lavender oil served as model mixtures. This study advances the field by (i) showing accelerated passive dosing kinetics for 68 cracked gas oil constituents with typical equilibration times of 5-10 min and for 21 cederwood Virginia oil constituents with typical equilibration times < 1 h, (ii) demonstrating how to control mixture concentration and composition in aquatic tests, and (iii) discussing the fundamental differences between solvent spiking, water-accommodated fractions, and passive dosing.
Collapse
Affiliation(s)
- Rikke Hammershøj
- Department of Environmental Engineering, Technical University of Denmark, Bygningstorvet, Building 115, 2800 Kongens Lyngby, Denmark
| | - Heidi Birch
- Department of Environmental Engineering, Technical University of Denmark, Bygningstorvet, Building 115, 2800 Kongens Lyngby, Denmark
| | - Karina K Sjøholm
- Department of Environmental Engineering, Technical University of Denmark, Bygningstorvet, Building 115, 2800 Kongens Lyngby, Denmark
| | - Philipp Mayer
- Department of Environmental Engineering, Technical University of Denmark, Bygningstorvet, Building 115, 2800 Kongens Lyngby, Denmark
| |
Collapse
|
18
|
Joudan S, Liu R, D'eon JC, Mabury SA. Unique analytical considerations for laboratory studies identifying metabolic products of per- and polyfluoroalkyl substances (PFASs). Trends Analyt Chem 2020. [DOI: 10.1016/j.trac.2019.02.032] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
|
19
|
Peng B, Liu M, Han Y, Wanjaya ER, Fang M. Competitive Biotransformation Among Phenolic Xenobiotic Mixtures: Underestimated Risks for Toxicity Assessment. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:12081-12090. [PMID: 31532198 DOI: 10.1021/acs.est.9b04968] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Humans are inevitably exposed to a complex mixture of organic contaminants (i.e., xenobiotics) through diet, environment, and behavior. Biotransformation makes key contributions to the elimination of xenobiotics and greatly mediates the toxicity. However, most biotransformation studies were conducted using individual chemical, and whether coexposure of multiple environmental chemicals will affect each other's fate in the human body is still in its infancy. In this study, bisphenol A (BPA) was selected as a model compound. Its biotransformation was investigated under single exposure/coexposure to other phenolic xenobiotics (triclosan, tetrabromobisphenol A, and bisphenol S) in liver microsome and cell models. The result shows that binary exposures exhibit significant inhibitory effects on the BPA metabolism, especially the sulfate conjugation. In combination of analysis on inhibition models and enzyme activity, the inhibition effect was suggested to be primarily driven by competition for metabolizing enzymes. A mixture with 22 phenolic chemicals was further examined to disrupt BPA at various human-relevant levels. Again, the result demonstrates significant inhibition on the BPA metabolism, indicating the possible natural existence of our finding. Overall, our results show that biotransformation of phenolic xenobiotics can be significantly altered by coexposure, which provides referential evidence on underestimated risks of simultaneous exposure to environmental toxicants.
Collapse
Affiliation(s)
- Bo Peng
- School of Civil and Environmental Engineering , Nanyang Technological University , 639798 , Singapore
- Nanyang Environment and Water Research Institute , Nanyang Technological University , 637141 , Singapore
| | - Min Liu
- School of Civil and Environmental Engineering , Nanyang Technological University , 639798 , Singapore
- Nanyang Environment and Water Research Institute , Nanyang Technological University , 637141 , Singapore
| | - Yuan Han
- Nanyang Environment and Water Research Institute , Nanyang Technological University , 637141 , Singapore
| | - Elvy Riani Wanjaya
- Nanyang Environment and Water Research Institute , Nanyang Technological University , 637141 , Singapore
| | - Mingliang Fang
- School of Civil and Environmental Engineering , Nanyang Technological University , 639798 , Singapore
- Nanyang Environment and Water Research Institute , Nanyang Technological University , 637141 , Singapore
- Singapore Phenome Center, Lee Kong Chian School of Medicine , Nanyang Technological University , Singapore 636921 , Singapore
| |
Collapse
|
20
|
Needham TP, Payne RB, Sowers KR, Ghosh U. Kinetics of PCB Microbial Dechlorination Explained by Freely Dissolved Concentration in Sediment Microcosms. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:7432-7441. [PMID: 31132852 DOI: 10.1021/acs.est.9b01088] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
While microbial dechlorination of polychlorinated biphenyls (PCBs) has been observed in sediments over the last 3 decades, translation to the field has been difficult due to a lack of a clear understanding of the kinetic limitations. To address this issue, the present study used passive dosing/sampling to accurately measure the biological rate of dechlorination of 2,3,4,5-tetrachlorobiphenyl (PCB 61) to 2,3,5-trichlorobiphenyl (PCB 23) by an organohalide-respiring bacterium, Dehalobium chlorocoercia (DF-1). The biological rates were measured over an environmentally relevant concentration range of 1-50 ng/L of freely dissolved concentrations with and without the presence of sediment in bench-scale microcosm studies. The rate of dechlorination was found to be linearly dependent on the freely dissolved concentration of PCB 61 both in sediment and in sediment-free microcosms. The observed rate of dechlorination in sediment microcosms could be predicted within a factor of 2 based on the kinetics measured in sediment-free microcosms. A threshold for dechlorination was not observed down to an aqueous concentration of about 1 ng/L PCB 61. We demonstrate that with the combination of an accurate measurement of the aqueous-phase dechlorination kinetics and an understanding of the site-specific partitioning characteristics, it is possible to predict PCB microbial dechlorination in sediments.
Collapse
|
21
|
Ott A, Martin TJ, Whale GF, Snape JR, Rowles B, Galay-Burgos M, Davenport RJ. Improving the biodegradability in seawater test (OECD 306). THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 666:399-404. [PMID: 30802655 DOI: 10.1016/j.scitotenv.2019.02.167] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 02/08/2019] [Accepted: 02/11/2019] [Indexed: 06/09/2023]
Abstract
Growth and extensive urbanisation of the human population has been accompanied by increased manufacture and use of chemical compounds. To classify the fate and behaviour of these compounds in the environment, a series of international standardised biodegradation screening tests (BSTs) were developed over 30 years ago. In recent years, regulatory emphasis (e.g. REACH) has shifted from measuring biodegradation towards prioritisations based on chemical persistence. In their current guise, BSTs are ineffective as screens for persistence. The marine BST OECD 306 in particular is prone to high levels of variation and produces a large number of fails, many of which can be considered false negatives. An ECETOC funded two-day workshop of academia, industry and regulatory bodies was held in 2015 to discuss improvements to the marine BSTs based on previous research findings from the Cefic LRI ECO11 project and other foregoing studies. During this workshop, methodological improvements to the OECD 306 test were discussed, in addition to clarifying guidance on testing and interpretation of results obtained from marine BSTs (such as pass criteria, lag phases, freshwater read across and complex substances). Methodologically: (i) increasing bacterial cell concentrations to better represent the bacterial diversity inherent in the sampled environments; and (ii) increasing test durations to investigate extended lag phases observed in marine assessments, were recommended to be validated in a multi-institutional ring test.
Collapse
Affiliation(s)
- Amelie Ott
- Newcastle University, School of Engineering, Newcastle-upon-Tyne NE1 7RU, UK.
| | - Timothy J Martin
- Newcastle University, School of Engineering, Newcastle-upon-Tyne NE1 7RU, UK.
| | - Graham F Whale
- Shell International Ltd., Risk Science Team, 4 York road, London SE1 7NA, UK.
| | - Jason R Snape
- Newcastle University, School of Engineering, Newcastle-upon-Tyne NE1 7RU, UK; AstraZeneca Global Environment, Mereside, Alderley Park, Macclesfield, Cheshire SK10 4TG, UK; School of Life Sciences, Gibbet Hill Campus, The University of Warwick, Coventry CV4 7AL, UK.
| | - Bob Rowles
- Centre for Environment, Fisheries and Aquaculture Science (Cefas), Pakefield Road, Lowestoft NR33 0HT, UK.
| | - Malyka Galay-Burgos
- European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC), Avenue Edmond Van Nieuwenhuyse 2, 1160 Auderghem, Belgium.
| | - Russell J Davenport
- Newcastle University, School of Engineering, Newcastle-upon-Tyne NE1 7RU, UK.
| |
Collapse
|
22
|
Hammershøj R, Birch H, Redman AD, Mayer P. Mixture Effects on Biodegradation Kinetics of Hydrocarbons in Surface Water: Increasing Concentrations Inhibited Degradation whereas Multiple Substrates Did Not. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:3087-3094. [PMID: 30801186 DOI: 10.1021/acs.est.9b00638] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Most biodegradation tests are conducted using single chemicals at high concentrations, although these chemicals are present in the environment as mixtures at low concentrations. A partitioning-based platform was recently developed for biodegradation testing of composed mixtures of hydrophobic chemicals at ng/L to μg/L concentrations. We used this platform to study the concentration and mixture effect on biodegradation kinetics. Biodegradation tests were conducted in 20 mL vials using environmental water samples as inocula. Passive dosing was applied (1) to vary initial test concentrations of individual test compounds and (2) to vary the number of mixture components between 1 and 16. Automated solid-phase microextraction coupled to gas chromatography-mass spectrometry was used to measure substrate depletion relative to abiotic controls. The number of mixture components had no or only a limited effect on the biodegradation half times for three compounds when tested at environmentally relevant concentrations. In contrast, longer lag phases and half lives were observed for single compounds when tested at higher concentrations that approached aqueous solubility. The obtained results support that simultaneous testing of multiple chemicals at low concentrations can accelerate the generation of biodegradation kinetic data, which are more environmentally relevant compared with data from tests conducted with single chemicals at much higher concentrations.
Collapse
Affiliation(s)
- Rikke Hammershøj
- Technical University of Denmark , Department of Environmental Engineering , Bygningstorvet, Building 115 , 2800 Kgs. Lyngby , Denmark
| | - Heidi Birch
- Technical University of Denmark , Department of Environmental Engineering , Bygningstorvet, Building 115 , 2800 Kgs. Lyngby , Denmark
| | - Aaron D Redman
- ExxonMobil Biomedical Science, Inc. , Annandale , New Jersey 08801 , United States
| | - Philipp Mayer
- Technical University of Denmark , Department of Environmental Engineering , Bygningstorvet, Building 115 , 2800 Kgs. Lyngby , Denmark
| |
Collapse
|
23
|
Trac LN, Schmidt SN, Mayer P. Headspace passive dosing of volatile hydrophobic chemicals - Aquatic toxicity testing exactly at the saturation level. CHEMOSPHERE 2018; 211:694-700. [PMID: 30098565 DOI: 10.1016/j.chemosphere.2018.07.150] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 07/23/2018] [Accepted: 07/24/2018] [Indexed: 06/08/2023]
Abstract
It is challenging to conduct aquatic tests with highly hydrophobic and volatile chemicals while avoiding substantial sorptive and evaporative losses. A simple and versatile headspace passive dosing (HS-PD) method was thus developed for such chemicals: The pure liquid test chemical was added to a glass insert, which was then placed with the open end in the headspace of a closed test system containing aqueous test medium. The test chemical served as the dominating partitioning donor for establishing and maintaining maximum exposure levels in the headspace and aqueous solution, without direct contact between the donor and the test medium. The HS-PD method was cross validated against passive dosing with a saturated silicone elastomer, using headspace gas chromatography as analytical instrument and saturated vapors as reference. The HS-PD method was then applied to control the exposure in algal growth inhibition tests with the green algae Raphidocelis subcapitata. The model chemicals were C9-C14 n-alkanes and the cyclic volatile methyl siloxanes octamethyltetracyclosiloxane (D4) and decamethylpentacyclosiloxane (D5). Growth rate inhibition at the solubility limit was 100% for C9-C13 n-alkanes and 53 ± 31% (95% CI) for tetradecane. A moderate inhibition of 11 ± 4% (95% CI) was observed for D4, whereas no inhibition was observed for D5. The present study introduces an effective method for aquatic toxicity testing of a difficult-to-test group of chemicals and provides an improved experimental basis for investigating toxicity cut-offs.
Collapse
Affiliation(s)
- Lam Ngoc Trac
- Department of Environmental Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark.
| | - Stine Nørgaard Schmidt
- Department of Environmental Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Philipp Mayer
- Department of Environmental Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| |
Collapse
|
24
|
Jimenez-Sanchez C, Wick LY, Ortega-Calvo JJ. Impact of Chemoeffectors on Bacterial Motility, Transport, and Contaminant Degradation in Sand-Filled Percolation Columns. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:10673-10679. [PMID: 30113820 DOI: 10.1021/acs.est.8b02370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Chemoeffector-mediated bacterial motility and tactic swimming are major drivers for contaminant accessibility and biodegradation at submillimeter scales. In sand-filled percolated columns we tested how and to what degree chemoeffectors influenced bacterial transport and thereby promoted accessibility and degradation of distantly located 14C-naphthalene (NAH) at the centimeter scale. Sunflower root exudates and silver nanoparticles (AgNPs) were used as chemoeffectors to stimulate opposing effects of motility and tactic swimming of NAH-degrading Pseudomonas putida G7. Sunflower exudates prompted smooth bacterial movement and positive taxis, while AgNPs induced tortuous movement and repellent responses. Compared to chemoeffector-free controls exudates reduced deposition and stimulated bacterial transport during percolation experiments. AgNPs, however, provoked bacterial deposition and concomitant saturation of the collector surfaces (filter blocking) that led to progressively increased percolation of cells. Despite mechanistic differences, both motility patterns supported bacterial transport and promoted mineralization rates of NAH desorbing from a source placed at the column outlet. Observed mineralization rates in the presence of the chemoeffectors were 5-fold higher than those in their absence and similar to NAH-mineralization in well-stirred batch assays. Our results indicate that chemically mediated, small-scale bacterial motility patterns may become relevant for long-distance bacterial transport and the biodegradation of patchy contaminants at higher scales, respectively.
Collapse
Affiliation(s)
- Celia Jimenez-Sanchez
- Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS-CSIC) , Avenida Reina Mercedes, 10 , E-41012 - Seville , Spain
| | - Lukas Y Wick
- UFZ Helmholtz Centre for Environmental Research , Permosertraße 15 , D-04318 Leipzig , Germany
| | - Jose-Julio Ortega-Calvo
- Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS-CSIC) , Avenida Reina Mercedes, 10 , E-41012 - Seville , Spain
| |
Collapse
|
25
|
Birch H, Hammershøj R, Mayer P. Determining Biodegradation Kinetics of Hydrocarbons at Low Concentrations: Covering 5 and 9 Orders of Magnitude of K ow and K aw. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:2143-2151. [PMID: 29376649 DOI: 10.1021/acs.est.7b05624] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
A partitioning-based experimental platform was developed and applied to determine primary biodegradation kinetics of 53 hydrocarbons at ng/L to μg/L concentrations covering C8-C20, 11 structural classes, and several orders of magnitude in hydrophobicity and volatility: (1) Passive dosing from a loaded silicone donor was used to set the concentration of each hydrocarbon in mixture stock solutions; (2) these solutions were combined with environmental water samples in gastight auto sampler vials for 1-100 days incubation, and (3) automated solid phase microextraction (SPME) coupled to GC-MS was applied directly on these test systems for measuring primary biodegradation relative to abiotic controls. First order biodegradation kinetics were obtained for 40 hydrocarbons in activated sludge filtrate, 18 in seawater, and 21 in lake water. Water phase half-lives in seawater and lake water were poorly related to hydrophobicity and volatility but were, with a few exceptions, within a factor of 10 or shorter than BioHCwin predictions. The most persistent hydrocarbons, 1,1,4,4,6-pentamethyldecalin, perhydropyrene, 1,2,3,6,7,8-hexahydropyrene, and 2,2,4,4,6,8,8-heptamethylnonane, showed limited or inconsistent degradation in all three environmental media. This biodegradation approach can cover a large chemical space at low substrate concentrations, which makes it highly suited for optimizing predictive models for environmental biodegradation.
Collapse
Affiliation(s)
- Heidi Birch
- Department of Environmental Engineering, Technical University of Denmark , Bygningstorvet, Building 115, 2800 Kongens Lyngby, Denmark
| | - Rikke Hammershøj
- Department of Environmental Engineering, Technical University of Denmark , Bygningstorvet, Building 115, 2800 Kongens Lyngby, Denmark
| | - Philipp Mayer
- Department of Environmental Engineering, Technical University of Denmark , Bygningstorvet, Building 115, 2800 Kongens Lyngby, Denmark
| |
Collapse
|
26
|
Tcaciuc AP, Borrelli R, Zaninetta LM, Gschwend PM. Passive sampling of DDT, DDE and DDD in sediments: accounting for degradation processes with reaction-diffusion modeling. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2018; 20:220-231. [PMID: 29264604 DOI: 10.1039/c7em00501f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Passive sampling is becoming a widely used tool for assessing freely dissolved concentrations of hydrophobic organic contaminants in environmental media. For certain media and target analytes, the time to reach equilibrium exceeds the deployment time, and in such cases, the loss of performance reference compounds (PRCs), loaded in the sampler before deployment, is one of the common ways used to assess the fractional equilibration of target analytes. The key assumption behind the use of PRCs is that their release is solely diffusion driven. But in this work, we show that PRC transformations in the sediment can have a measurable impact on the PRC releases and even allow estimation of that compound's transformation rate in the environment of interest. We found that in both field and lab incubations, the loss of the 13C 2,4'-DDT PRC from a polyethylene (PE) passive sampler deployed at the sediment-water interface was accelerated compared to the loss of other PRCs (13C-labeled PCBs, 13C-labeled DDE and DDD). The DDT PRC loss was also accompanied by accumulation in the PE of its degradation product, 13C 2,4'-DDD. Using a 1D reaction-diffusion model, we deduced the in situ degradation rates of DDT from the measured PRC loss. The in situ degradation rates increased with depth into the sediment bed (0.14 d-1 at 0-10 cm and 1.4 d-1 at 30-40 cm) and although they could not be independently validated, these rates compared favorably with literature values. This work shows that passive sampling users should be cautious when choosing PRCs, as degradation processes can affect some PRC's releases from the passive sampler. More importantly, this work opens up the opportunity for novel applications of passive samplers, particularly with regard to investigating in situ degradation rates, pathways, and products for both legacy and emerging contaminants. However, further work is needed to confirm that the rates deduced from model fitting of PRC loss are a true reflection of DDT transformation rates in sediments.
Collapse
|
27
|
Birch H, Hammershøj R, Comber M, Mayer P. Biodegradation of hydrocarbon mixtures in surface waters at environmentally relevant levels - Effect of inoculum origin on kinetics and sequence of degradation. CHEMOSPHERE 2017; 184:400-407. [PMID: 28609746 DOI: 10.1016/j.chemosphere.2017.05.169] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 05/24/2017] [Accepted: 05/29/2017] [Indexed: 06/07/2023]
Abstract
Biodegradation is a dominant removal process for many organic pollutants, and biodegradation tests serve as tools for assessing their environmental fate within regulatory risk assessment. In simulation tests, the inoculum is not standardized, varying in microbial quantity and quality, thereby potentially impacting the observed biodegradation kinetics. In this study we investigated the effect of inoculum origin on the biodegradation kinetics of hydrocarbons for five inocula from surface waters varying in urbanization and thus expected pre-exposure to petroleum hydrocarbons. A new biodegradation method for testing mixtures of hydrophobic chemicals at trace concentrations was demonstrated: Aqueous solutions containing 9 hydrocarbons were generated by passive dosing and diluted with surface water resulting in test systems containing native microorganisms exposed to test substances at ng-μg/L levels. Automated Headspace Solid Phase Microextraction coupled to GC-MS was applied directly to these test systems to determine substrate depletion relative to abiotic controls. Lag phases were generally less than 8 days. First order rate constants were within one order of magnitude for each hydrocarbon in four of the five waters but lower in water from a rural lake. The sequence of degradation between the 9 hydrocarbons showed similar patterns in the five waters indicating the potential for using selected hydrocarbons for benchmarking between biodegradation tests. Degradation half-times were shorter than or within one order of magnitude of BioHCwin predictions for 8 of 9 hydrocarbons. These results showed that location choice is important for biodegradation kinetics and can provide a relevant input to aquatic exposure and fate models.
Collapse
Affiliation(s)
- Heidi Birch
- Technical University of Denmark, Department of Environmental Engineering, Building 115, 2800 Kgs. Lyngby, Denmark.
| | - Rikke Hammershøj
- Technical University of Denmark, Department of Environmental Engineering, Building 115, 2800 Kgs. Lyngby, Denmark.
| | - Mike Comber
- Mike Comber Consulting, Bridford, Exeter, UK.
| | - Philipp Mayer
- Technical University of Denmark, Department of Environmental Engineering, Building 115, 2800 Kgs. Lyngby, Denmark.
| |
Collapse
|
28
|
Stibany F, Ewald F, Miller I, Hollert H, Schäffer A. Improving the reliability of aquatic toxicity testing of hydrophobic chemicals via equilibrium passive dosing - A multiple trophic level case study on bromochlorophene. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 584-585:96-104. [PMID: 28142058 DOI: 10.1016/j.scitotenv.2017.01.082] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 01/13/2017] [Accepted: 01/13/2017] [Indexed: 04/15/2023]
Abstract
The main objective of the present study was to improve the reliability and practicability of aquatic toxicity testing of hydrophobic chemicals based upon the model substance bromochlorophene (BCP). Therefore, we adapted a passive dosing format to test the toxicity of BCP at different concentrations and in multiple test systems with aquatic organisms of various trophic levels. At the same time, the method allowed for the accurate determination of exposure concentrations (i.e., in the presence of exposed organisms; Ctest) and freely dissolved concentrations (i.e., without organisms present; Cfree) of BCP in all tested media. We report on the joint adaptation of three ecotoxicity tests - algal growth inhibition, Daphnia magna immobilization, and fish-embryo toxicity - to a silicone O-ring based equilibrium passive dosing format. Effect concentrations derived by passive dosing methods were compared with corresponding effect concentrations derived by standard co-solvent setups. The passive dosing format led to EC50-values in the lower μgL-1 range for algae, daphnids, and fish embryos, whereas increased effect concentrations were measured in the co-solvent setups for algae and daphnids. This effect once more shows that passive dosing might offer advantages over standard methods like co-solvent setups when it comes to a reliable risk assessment of hydrophobic substances. The presented passive dosing setup offers a facilitated, practical, and repeatable way to test hydrophobic chemicals on their toxicity to aquatic organisms, and is an ideal basis for the detailed investigation of this important group of chemicals.
Collapse
Affiliation(s)
- Felix Stibany
- Institute for Environmental Research (Biology V), RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany.
| | - Franziska Ewald
- Institute for Environmental Research (Biology V), RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
| | - Ina Miller
- Institute for Environmental Research (Biology V), RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
| | - Henner Hollert
- Institute for Environmental Research (Biology V), RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
| | - Andreas Schäffer
- Institute for Environmental Research (Biology V), RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
| |
Collapse
|
29
|
Lin J, Emberger M. Study of the photodegradation of a fragrance ingredient for aquatic environmental fate assessment. CHEMOSPHERE 2017; 173:485-493. [PMID: 28131918 DOI: 10.1016/j.chemosphere.2017.01.083] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 01/09/2017] [Accepted: 01/14/2017] [Indexed: 06/06/2023]
Abstract
Photodegradation is an important abiotic degradation process to be taken into account for more accurate assessment of the fate of chemicals in the aquatic environment, especially those that are not readily biodegradable. Although the significant role of indirect photodegradation in the environmental fate of chemicals has been revealed in recent research, because of the many confounding factors affecting its kinetics, no straightforward approaches can be used to investigate this degradation process for environmental fate assessment. The indirect photodegradation of a fragrance ingredient named Pamplewood was studied in this work for its fate assessment. Indirect photodegradation rates under various indoor and outdoor conditions were measured by using an LC-MS method. Although the half-lives varied from 4 to 13 days, they collectively indicated that Pamplewood is intrinsically photolabile and can undergo rapid photodegradation. Results from quencher experiments revealed that ⋅OH was the main reactive intermediate responsible for indirect photodegradation, with a half-life of about 18 days in sunlit surface water, based on the experimentally determined second-order rate constant (8.48 ± 0.19 × 109 M-1 s-1). Photodegradation products of Pamplewood were also studied by GC-MS, LC-MS and total organic carbon content analyses. The results indicated that intermediates of Pamplewood photodegradation continued to photodegrade into smaller and more polar species. Complete mineralization of Pamplewood was observed when it was reacted with hydroxyl radicals in an aqueous solution. This novel approach can be applied for a more realistic environmental fate assessment of other non-readily biodegradable, hydrolysis-resistant, and non-sunlight-absorbing fragrance ingredients.
Collapse
Affiliation(s)
- Jianming Lin
- Firmenich Inc., North America R&D, PO Box 5880, Princeton, NJ 08543, USA.
| | - Matthew Emberger
- Firmenich Inc., North America R&D, PO Box 5880, Princeton, NJ 08543, USA
| |
Collapse
|
30
|
Stibany F, Schmidt SN, Schäffer A, Mayer P. Aquatic toxicity testing of liquid hydrophobic chemicals - Passive dosing exactly at the saturation limit. CHEMOSPHERE 2017; 167:551-558. [PMID: 27770722 DOI: 10.1016/j.chemosphere.2016.10.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 09/30/2016] [Accepted: 10/03/2016] [Indexed: 06/06/2023]
Abstract
The aims of the present study were (1) to develop a passive dosing approach for aquatic toxicity testing of liquid substances with very high Kow values and (2) to apply this approach to the model substance dodecylbenzene (DDB, Log Kow = 8.65). The first step was to design a new passive dosing format for testing DDB exactly at its saturation limit. Silicone O-rings were saturated by direct immersion in pure liquid DDB, which resulted in swelling of >14%. These saturated O-rings were used to establish and maintain DDB exposure exactly at the saturation limit throughout 72-h algal growth inhibition tests with green algae Raphidocelis subcapitata. Growth rate inhibition at DDB solubility was 13 ± 5% (95% CI) in a first and 8 ± 3% (95% CI) in a repeated test, which demonstrated that improved exposure control can lead to good precision and repeatability of toxicity tests. This moderate toxicity at chemical activity of unity was higher than expected relative to a reported hydrophobicity cut-off in toxicity, but lower than expected relative to a reported chemical activity range for baseline toxicity. The present study introduces a new effective approach for toxicity testing of an important group of challenging chemicals, while providing a basis for investigating toxicity cut-off theories.
Collapse
Affiliation(s)
- Felix Stibany
- Institute for Environmental Research (Biology V), RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany; Department of Environmental Engineering, Technical University of Denmark, Bygningstorvet B115, DK-2800 Kongens Lyngby, Denmark.
| | - Stine Nørgaard Schmidt
- Department of Environmental Engineering, Technical University of Denmark, Bygningstorvet B115, DK-2800 Kongens Lyngby, Denmark
| | - Andreas Schäffer
- Institute for Environmental Research (Biology V), RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
| | - Philipp Mayer
- Department of Environmental Engineering, Technical University of Denmark, Bygningstorvet B115, DK-2800 Kongens Lyngby, Denmark
| |
Collapse
|
31
|
Otto S, Harms H, Wick LY. Effects of predation and dispersal on bacterial abundance and contaminant biodegradation. FEMS Microbiol Ecol 2016; 93:fiw241. [DOI: 10.1093/femsec/fiw241] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 12/01/2016] [Indexed: 11/12/2022] Open
|
32
|
Modrzyński JJ, Christensen JH, Mayer P, Brandt KK. Limited recovery of soil microbial activity after transient exposure to gasoline vapors. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2016; 216:826-835. [PMID: 27376993 DOI: 10.1016/j.envpol.2016.06.054] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 06/22/2016] [Accepted: 06/23/2016] [Indexed: 06/06/2023]
Abstract
During gasoline spills complex mixtures of toxic volatile organic compounds (VOCs) are released to terrestrial environments. Gasoline VOCs exert baseline toxicity (narcosis) and may thus broadly affect soil biota. We assessed the functional resilience (i.e. resistance and recovery of microbial functions) in soil microbial communities transiently exposed to gasoline vapors by passive dosing via headspace for 40 days followed by a recovery phase of 84 days. Chemical exposure was characterized with GC-MS, whereas microbial activity was monitored as soil respiration (CO2 release) and soil bacterial growth ([(3)H]leucine incorporation). Microbial activity was strongly stimulated and inhibited at low and high exposure levels, respectively. Microbial growth efficiency decreased with increasing exposure, but rebounded during the recovery phase for low-dose treatments. Although benzene, toluene, ethylbenzene and xylene (BTEX) concentrations decreased by 83-97% during the recovery phase, microbial activity in high-dose treatments did not recover and numbers of viable bacteria were 3-4 orders of magnitude lower than in control soil. Re-inoculation with active soil microorganisms failed to restore microbial activity indicating residual soil toxicity, which could not be attributed to BTEX, but rather to mixture toxicity of more persistent gasoline constituents or degradation products. Our results indicate a limited potential for functional recovery of soil microbial communities after transient exposure to high, but environmentally relevant, levels of gasoline VOCs which therefore may compromise ecosystem services provided by microorganisms even after extensive soil VOC dissipation.
Collapse
Affiliation(s)
- Jakub J Modrzyński
- Department of Plant and Environmental Sciences, University of Copenhagen, 1871, Frederiksberg, Denmark.
| | - Jan H Christensen
- Department of Plant and Environmental Sciences, University of Copenhagen, 1871, Frederiksberg, Denmark.
| | - Philipp Mayer
- Department of Environmental Engineering, Technical University of Denmark, 2800, Kongens Lyngby, Denmark; Department of Environmental Science, Aarhus University, 4000, Roskilde, Denmark.
| | - Kristian K Brandt
- Department of Plant and Environmental Sciences, University of Copenhagen, 1871, Frederiksberg, Denmark.
| |
Collapse
|
33
|
Otto S, Banitz T, Thullner M, Harms H, Wick LY. Effects of Facilitated Bacterial Dispersal on the Degradation and Emission of a Desorbing Contaminant. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:6320-6326. [PMID: 27195517 DOI: 10.1021/acs.est.6b00567] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The quantitative relationship between a compound's availability for biological removal and ecotoxicity is a key issue for retrospective risk assessment and remediation approaches. Here, we investigated the impact of facilitated bacterial dispersal at a model soil-atmosphere interface on the release, degradation, and outgassing of a semivolatile contaminant. We designed a laboratory microcosm with passive dosing of phenanthrene (PHE) to a model soil-atmosphere interface (agar surface) in the presence and absence of glass fibers known to facilitate the dispersal of PHE-degrading Pseudomonas fluorescens LP6a. We observed that glass fibers (used as a model to mimic a fungal hyphal network) resulted in (i) increased bacterial surface coverage, (ii) effective degradation of matrix-bound PHE, and (iii) substantially reduced PHE emission to locations beyond the contamination zone even at low bacterial surface coverage. Our data suggest that bacterial dispersal networks such as mycelia promote the optimized spatial arrangement of microbial populations to allow for effective contaminant degradation and reduction of potential hazard to organisms beyond a contaminated zone.
Collapse
Affiliation(s)
| | | | | | - Hauke Harms
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig , Deutscher Platz 5e, 04103 Leipzig, Germany
| | | |
Collapse
|
34
|
Defining and Controlling Exposure During In Vitro Toxicity Testing and the Potential of Passive Dosing. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2016; 157:263-292. [DOI: 10.1007/10_2015_5017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
|
35
|
Erythropel HC, Brown T, Maric M, Nicell JA, Cooper DG, Leask RL. Designing greener plasticizers: Effects of alkyl chain length and branching on the biodegradation of maleate based plasticizers. CHEMOSPHERE 2015; 134:106-112. [PMID: 25917507 DOI: 10.1016/j.chemosphere.2015.04.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 04/03/2015] [Accepted: 04/07/2015] [Indexed: 06/04/2023]
Abstract
The ubiquitous presence of the plasticizer di (2-ethylhexyl) phthalate (DEHP) in the environment is of concern due to negative biological effects associated with it and its metabolites. In particular, the metabolite mono (2-ethylhexyl) phthalate (MEHP) is a potential endocrine disruptor. Earlier work had identified the diester di (2-ethylhexyl) maleate (DEHM) as a potential greener candidate plasticizer to replace DEHP, yet its biodegradation rate was reported to be slow. In this study, we modified the side chains of maleate diesters to be linear (i.e., unbranched) alkyl chains that varied in length from ethyl to n-octyl. The plasticization efficiency of these compounds blended into PVC at 29 wt.% increased with the overall length of the molecule, but all compounds performed as well as or better than comparable samples with DEHP. Tests conducted with the equally long DEHM and dihexyl maleate (DHM) showed that branching has no effect on glass transition temperature (Tg) reduction efficiency. Biodegradation experiments with the common soil bacterium Rhodococcus rhodocrous in the presence of the plasticizer showed acceptable hydrolysis rates of maleates with unbranched side chains, while the branched DEHM showed almost no degradation. The addition of hexadecane as auxiliary carbon source improved hydrolysis rates. Temporary buildup of the respective monoester of the compounds were observed, but only in the case of the longest molecule, dioctyl maleate (DOM), did this buildup lead to growth inhibition of the bacteria. Maleates with linear side chains, if designed and tested properly, show promise as potential candidate plasticizers as replacements for DEHP.
Collapse
Affiliation(s)
- Hanno C Erythropel
- Department of Chemical Engineering, McGill University, Montréal, Québec, Canada
| | - Tobin Brown
- Department of Chemical Engineering, McGill University, Montréal, Québec, Canada
| | - Milan Maric
- Department of Chemical Engineering, McGill University, Montréal, Québec, Canada
| | - Jim A Nicell
- Department of Civil Engineering & Applied Mechanics, McGill University, Montréal, Québec, Canada
| | - David G Cooper
- Department of Chemical Engineering, McGill University, Montréal, Québec, Canada
| | - Richard L Leask
- Department of Chemical Engineering, McGill University, Montréal, Québec, Canada.
| |
Collapse
|
36
|
Roh JY, Lee H, Kwon JH. Changes in the expression of cyp35a family genes in the soil nematode Caenorhabditis elegans under controlled exposure to chlorpyrifos using passive dosing. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:10475-10481. [PMID: 25122055 DOI: 10.1021/es5027773] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In order to use sensitive molecular-level biomarkers for the evaluation of environmental risks, it is necessary to establish a quantitative dose-response relationship. Passive dosing is regarded as a promising new technique for maintaining a constant exposure condition of hydrophobic chemicals in the assay medium. The main goals of the present study were (1) to quantitatively compare gene expression results obtained using the passive dosing method and the conventional spiking method and (2) to investigate changes in gene expression with respect to the free concentration and exposure duration using passive dosing. Chlorpyrifos (CP), which is oxidized by the cytochrome P450 monooxygenases, was selected as a model chemical, and the expression of cytochrome P450 subfamily protein 35A gene series (cyp-35a1-5) was analyzed by quantitative real-time PCR on soil nematode Caenorhabditis elegans. Whereas the free concentration of CP rapidly decreased and the expression of cyp genes varied with the volume of exposure medium and the test duration when the spiking method was used, the free concentration in the assay medium was stable throughout the experiment when the passive dosing method was used. In addition, the level of gene expression increased with exposure time up to 8 h and with increasing CP concentration. The observed increased gene expression could be explained by increasing body residue concentration of CP with exposure time. In conclusion, quantitative dose-response relationships for gene expression biomarkers could be obtained for highly hydrophobic chemicals when the constant exposure condition is provided and the free concentration is used as the dose-metric.
Collapse
Affiliation(s)
- Ji-Yeon Roh
- Division of Environmental Science and Ecological Engineering, Korea University , 145 Anam-ro, Seongbuk-gu, Seoul 136-713, Republic of Korea
| | | | | |
Collapse
|
37
|
Lee YS, Lee DHY, Delafoulhouze M, Otton SV, Moore MM, Kennedy CJ, Gobas FAPC. In vitro biotransformation rates in fish liver S9: effect of dosing techniques. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2014; 33:1885-1893. [PMID: 24832019 DOI: 10.1002/etc.2636] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Revised: 03/07/2014] [Accepted: 05/11/2014] [Indexed: 06/03/2023]
Abstract
In vitro biotransformation assays are currently being explored to improve estimates of bioconcentration factors of potentially bioaccumulative organic chemicals in fish. The present study compares thin-film and solvent-delivery dosing techniques as well as single versus multiple chemical dosing for measuring biotransformation rates of selected polycyclic aromatic hydrocarbons in rainbow trout (Oncorhynchus mykiss) liver S9. The findings show that biotransformation rates of very hydrophobic substances can be accurately measured in thin-film sorbent-dosing assays from concentration-time profiles in the incubation medium but not from those in the sorbent phase because of low chemical film-to-incubation-medium mass-transfer rates at the incubation temperature of 13.5 °C required for trout liver assays. Biotransformation rates determined by thin-film dosing were greater than those determined by solvent-delivery dosing for chrysene (octanol-water partition coefficient [KOW ] =10(5.60) ) and benzo[a]pyrene (KOW =10(6.04) ), whereas there were no statistical differences in pyrene (KOW =10(5.18) ) biotransformation rates between the 2 methods. In sorbent delivery-based assays, simultaneous multiple-chemical dosing produced biotransformation rates that were not statistically different from those measured in single-chemical dosing experiments for pyrene and benzo[a]pyrene but not for chrysene. In solvent-delivery experiments, multiple-chemical dosing produced biotransformation rates that were much smaller than those in single-chemical dosing experiments for all test chemicals. While thin-film sorbent-phase and solvent delivery-based dosing methods are both suitable methods for measuring biotransformation rates of substances of intermediate hydrophobicity, thin-film sorbent-phase dosing may be more suitable for superhydrophobic chemicals.
Collapse
Affiliation(s)
- Yung-Shan Lee
- School of Resource and Environmental Management, Simon Fraser University, Burnaby, British Columbia, Canada
| | | | | | | | | | | | | |
Collapse
|
38
|
Lombard N, Ghosh U, Kjellerup BV, Sowers KR. Kinetics and threshold level of 2,3,4,5-tetrachlorobiphenyl dechlorination by an organohalide respiring bacterium. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:4353-60. [PMID: 24625226 PMCID: PMC3993611 DOI: 10.1021/es404265d] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Revised: 02/20/2014] [Accepted: 03/13/2014] [Indexed: 05/26/2023]
Abstract
The time required for a PCB-contaminated site to recover cannot yet be predicted due in part to lack of quantitative information on rates of PCB dechlorination in the porewater phase. We developed a method to measure rate of dechlorination in the aqueous phase at very low PCB concentrations. This approach utilizes a polymer functioning concurrently as a passive dosing system for maintaining a steady-state PCB substrate concentration in the water phase and as a passive equilibrium sampler to monitor the dechlorination product. Rates of dechlorination of 2,3,4,5-tetrachlorobiphenyl (PCB 61) to 2,3,5-trichlorobiphenyl (PCB 23) by an organohalide respiring bacterium, Dehalobium chlorocoercia DF-1, were measured over an environmentally relevant range of 1 to 500 ng L(-1) in sediment-free medium using a high concentration of cells (>10(6) cells mL(-1)). The results indicate that rate of dechlorination is a linear function of PCB substrate concentration below the maximum aqueous solubility of PCB 61 and occurs at concentrations as low as 1 ng L(-1). Demonstration of PCB 61 dechlorination at environmentally relevant concentrations suggests that low numbers of organohalide respiring bacteria rather than bioavailability accounts for low rates of dechlorination typically observed in sediments. Using passive samplers to measure the concentration of dissolved PCBs in the porewater combined with knowledge of congener-specific rates for organohalide respirer(s), it will be possible to project the in situ rate and final concentration of PCBs for a specific site after treatment by bioaugmentation.
Collapse
Affiliation(s)
- Nathalie
J. Lombard
- Department of Marine Biotechnology,
Institute of Marine Environmental
Technology, and Department of Chemical, Biochemical, and Environmental Engineering, University of Maryland Baltimore County, Baltimore, Maryland 21204, United States
| | - Upal Ghosh
- Department of Marine Biotechnology,
Institute of Marine Environmental
Technology, and Department of Chemical, Biochemical, and Environmental Engineering, University of Maryland Baltimore County, Baltimore, Maryland 21204, United States
| | - Birthe V. Kjellerup
- Department
of Biological Sciences, Goucher College, 1021 Dulaney Valley Road, Baltimore, Maryland 21204, United States
| | - Kevin R. Sowers
- Department of Marine Biotechnology,
Institute of Marine Environmental
Technology, and Department of Chemical, Biochemical, and Environmental Engineering, University of Maryland Baltimore County, Baltimore, Maryland 21204, United States
| |
Collapse
|
39
|
Tejeda-Agredano MC, Mayer P, Ortega-Calvo JJ. The effect of humic acids on biodegradation of polycyclic aromatic hydrocarbons depends on the exposure regime. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2014; 184:435-442. [PMID: 24121418 DOI: 10.1016/j.envpol.2013.09.031] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 09/15/2013] [Accepted: 09/18/2013] [Indexed: 06/02/2023]
Abstract
Binding of polycyclic aromatic hydrocarbons (PAHs) to dissolved organic matter (DOM) can reduce the freely dissolved concentration, increase apparent solubility or enhance diffusive mass transfer. To study the effects of DOM on biodegradation, we used phenanthrene and pyrene as model PAHs, soil humic acids as model DOM and a soil Mycobacterium strain as a representative degrader organism. Humic acids enhanced the biodegradation of pyrene when present as solid crystals but not when initially dissolved or provided by partitioning from a polymer. Synchronous fluorescence spectrophotometry, scintillation counting and a microscale diffusion technique were applied in order to determine the kinetics of dissolution and diffusive mass transfer of pyrene. We suggest that humic acids can enhance or inhibit biodegradation as a result of the balance of two opposite effects, namely, solubilization of the chemicals on the one hand and inhibition of cell adhesion to the pollutant source on the other.
Collapse
Affiliation(s)
- Maria-Carmen Tejeda-Agredano
- Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS-CSIC), Apartado 1052, E-41080 Seville, Spain; Department of Environmental Science, Aarhus University, P.O. Box 358, 4000 Roskilde, Denmark
| | | | | |
Collapse
|
40
|
Erythropel HC, Dodd P, Leask RL, Maric M, Cooper DG. Designing green plasticizers: influence of alkyl chain length on biodegradation and plasticization properties of succinate based plasticizers. CHEMOSPHERE 2013; 91:358-365. [PMID: 23340052 DOI: 10.1016/j.chemosphere.2012.11.061] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2012] [Revised: 11/07/2012] [Accepted: 11/22/2012] [Indexed: 06/01/2023]
Abstract
Phthalate diesters such as di (2-ethylhexyl) phthalate (DEHP) are considered ubiquitous contaminants and are poorly biodegraded in the environment. Moreover, both the parent compound and stable metabolites such as mono (2-ethylhexyl) phthalate (MEHP) are linked to several negative impacts on the environment and human health. Earlier work established that saturated diester compounds, such as succinates, showed better biodegradation characteristics and comparable plasticizer properties compared to DEHP. In this work we examine the effect of alkyl chain length of succinate molecules on plasticizer and biodegradation properties. This included both the side chains (n-ethyl to n-octyl) as well as substituents on the middle part of the succinate molecule. We showed that the common soil bacterium Rhodococcus rhodocrous could rapidly break down all unsubstituted succinates, without the appearance of stable metabolites. Furthermore, the organisms used the plasticizer metabolites as carbon source. The introduction of a large cyclohexyl substituent on the succinate resulted in a poorer degradation rate. Glass Transition Temperature (Tg) measurements were performed to evaluate plasticizer properties and showed that longer side chains reduced the Tg more efficiently, while large cyclohexyl substituents on the succinate decreased this effect. However, all compounds performed better or equal to DEHP at reducing the Tg.
Collapse
Affiliation(s)
- Hanno C Erythropel
- McGill University, Department of Chemical Engineering, Wong Building, 3610 Rue University, Montréal, Québec, Canada H3A 2B2.
| | | | | | | | | |
Collapse
|
41
|
Smith KEC, Heringa MB, Uytewaal M, Mayer P. The dosing determines mutagenicity of hydrophobic compounds in the Ames II assay with metabolic transformation: passive dosing versus solvent spiking. Mutat Res 2012; 750:12-8. [PMID: 22989744 DOI: 10.1016/j.mrgentox.2012.07.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2011] [Revised: 06/15/2012] [Accepted: 07/25/2012] [Indexed: 11/20/2022]
Abstract
The Ames II bacterial mutagenicity assay is a new version of the standard Ames test for screening chemicals for genotoxic activity. However, the use of plastic micro-titer plates has drawbacks in the case of testing hydrophobic mutagens, since sorptive and other losses make it difficult to control and define the exposure concentrations, and they reduce availability for bacterial uptake or to the S9 enzymes. With passive dosing, a biocompatible polymer such as silicone is loaded with the test compound and acts as a partitioning source. It compensates for any losses and results in stable freely dissolved concentrations. Passive dosing using silicone O-rings was applied in the Ames II assay to measure PAH mutagenicity in strains TA98 and TAMix - a mixture of six different bacterial strains detecting six different base-pair substitutions - after metabolic activation by S9. Initially, 10 PAHs were tested with passive dosing from saturated O-rings, aiming at levels in the test medium close to aqueous solubility. Fluoranthene, pyrene and benzo(a)pyrene were mutagenic in both TA98 and TAMix, whereas benz(a)anthracene was mutagenic in TA98 only. The concentration-dependent mutagenic activity of benzo(a)pyrene was then compared for passive dosing and solvent spiking. With spiking, nominal concentrations greatly exceeded aqueous solubility before mutagenicity was observed, due to sorptive losses and limiting dissolution kinetics. In contrast, the passive dosing concentration-response curves were more reproducible, and shifted towards lower concentrations by several orders of magnitude. This study raises fundamental questions about how to introduce hydrophobic test substances in the Ames II assay with biotransformation, since the measured mutagenicity not only depends on the compound potency but also on its supply, sorption and consumption during the assay.
Collapse
Affiliation(s)
- Kilian E C Smith
- Department of Environmental Science, Aarhus University, Roskilde, Denmark.
| | | | | | | |
Collapse
|