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Xu W, Pignatello JJ, Mitch WA. Reduction of nitroaromatics sorbed to black carbon by direct reaction with sorbed sulfides. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:3419-3426. [PMID: 25671390 DOI: 10.1021/es5045198] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Sorption to black carbons is an important sink for organic contaminants in sediments. Previous research has suggested that black carbons (graphite, activated carbon, and biochar) mediate the degradation of nitrated compounds by sulfides by at least two different pathways: reduction involving electron transfer from sulfides through conductive carbon regions to the target contaminant (nitroglycerin) and degradation by sulfur-based intermediates formed by sulfide oxidation (RDX). In this study, we evaluated the applicability of black carbon-mediated reactions to a wider variety of contaminant structures, including nitrated and halogenated aromatic compounds, halogenated heterocyclic aromatic compounds, and halogenated alkanes. Among these compounds, black carbon-mediated transformation by sulfides over a 3-day time scale was limited to nitroaromatic compounds. The reaction for a series of substituted nitroaromatics proceeded by reduction, as indicated by formation of 3-bromoaniline from 3-bromonitrobenzene, and inverse correlation of log kobs with energy of the lowest unoccupied molecular orbital (ELUMO). The log kobs was correlated with sorbed sulfide concentration, but no reduction of 3-bromonitrobenzene was observed in the presence of graphite and sulfite, thiosulfate, or polysulfides. Whereas nitroglycerin reduction occurred in an electrochemical cell containing sheet graphite electrodes in which the reagents were placed in separate compartments, nitroaromatic reduction only occurred when sulfides were present in the same compartment. The results suggest that black carbon-mediated reduction of sorbed nitroaromatics by sulfides involves electron transfer directly from sorbed sulfides rather than transfer of electrons through conductive carbon regions. The existence of three different reaction pathways suggests a complexity to the sulfide-carbon system compared to the iron-carbon system, where contaminants are reduced by electron transfer through conductive carbon regions.
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Affiliation(s)
- Wenqing Xu
- †Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520, United States
- ∥Department of Civil and Environmental Engineering, Villanova University, Villanova, Pennsylvania 19085, United States
| | - Joseph J Pignatello
- †Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520, United States
- ‡Department of Environmental Sciences, Connecticut Agricultural Experiment Station, 123 Huntington Street, New Haven, Connecticut 06504-1106, United States
| | - William A Mitch
- §Department of Civil and Environmental Engineering, Stanford University, Stanford, California 94305-4020, United States
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Rakowska MI, Kupryianchyk D, Koelmans AA, Grotenhuis T, Rijnaarts HHM. Equilibrium and kinetic modeling of contaminant immobilization by activated carbon amended to sediments in the field. WATER RESEARCH 2014; 67:96-104. [PMID: 25262554 DOI: 10.1016/j.watres.2014.07.046] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2014] [Revised: 07/28/2014] [Accepted: 07/30/2014] [Indexed: 05/02/2023]
Abstract
Addition of activated carbons (AC) to polluted sediments and soils is an attractive remediation technique aiming at reducing pore water concentrations of hydrophobic organic contaminants (HOCs). In this study, we present (pseudo-)equilibrium as well as kinetic parameters for sorption of a series of PAHs and PCBs to powdered and granular activated carbons (AC) after three different sediment treatments: sediment mixed with powdered AC (PAC), sediment mixed with granular AC (GAC), and addition of GAC followed by 2 d mixing and subsequent removal ('sediment stripping'). Remediation efficiency was assessed by quantifying fluxes of PAHs towards SPME passive samplers inserted in the sediment top layer, which showed that the efficiency decreased in the order of PAC > GAC stripping > GAC addition. Sorption was very strong to PAC, with Log KAC (L/kg) values up to 10.5. Log KAC values for GAC ranged from 6.3-7.1 and 4.8-6.2 for PAHs and PCBs, respectively. Log KAC values for GAC in the stripped sediment were 7.4-8.6 and 5.8-7.7 for PAH and PCB. Apparent first order adsorption rate constants for GAC (kGAC) in the stripping scenario were calculated with a first-order kinetic model and ranged from 1.6 × 10(-2) (PHE) to 1.7 × 10(-5) d(-1) (InP). Sorption affinity parameters did not change within 9 months post treatment, confirming the longer term effectiveness of AC in field applications for PAC and GAC.
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Affiliation(s)
- Magdalena I Rakowska
- Subdepartment of Environmental Technology, Department of Agrotechnology and Food Science, Wageningen University, P.O. Box 17, 6700 AA Wageningen, The Netherlands.
| | - Darya Kupryianchyk
- Aquatic Ecology and Water Quality Management Group, Department of Environmental Sciences, Wageningen University, P.O. Box 47, 6700 AA Wageningen, The Netherlands; Department of Environmental Technology, Norwegian Geotechnical Institute, 0806 Oslo, Norway
| | - Albert A Koelmans
- Aquatic Ecology and Water Quality Management Group, Department of Environmental Sciences, Wageningen University, P.O. Box 47, 6700 AA Wageningen, The Netherlands; IMARES - Institute for Marine Resources & Ecosystem Studies, Wageningen UR, P.O. Box 68, 1970 AB IJmuiden, The Netherlands
| | - Tim Grotenhuis
- Subdepartment of Environmental Technology, Department of Agrotechnology and Food Science, Wageningen University, P.O. Box 17, 6700 AA Wageningen, The Netherlands
| | - Huub H M Rijnaarts
- Subdepartment of Environmental Technology, Department of Agrotechnology and Food Science, Wageningen University, P.O. Box 17, 6700 AA Wageningen, The Netherlands
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53
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Poot A, Jonker MTO, Gillissen F, Koelmans AA. Explaining PAH desorption from sediments using Rock Eval analysis. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2014; 193:247-253. [PMID: 25063912 DOI: 10.1016/j.envpol.2014.06.041] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Revised: 06/27/2014] [Accepted: 06/29/2014] [Indexed: 06/03/2023]
Abstract
Here, we provide Rock Eval and black carbon (BC) characteristics and polycyclic aromatic hydrocarbon (PAH) distribution coefficients (KD) for sediments from the Danube, Elbe, Ebro, and Meuse river basins. PAH desorption kinetic parameters were determined using sequential Tenax extractions. We show that residual carbon (RC) from Rock Eval analysis is an adequate predictor of fast, slow, and very slow desorbing fractions of 4-ring PAHs. RC correlated better than BC, the latter constituting only 7% of RC. A dual domain sorption model was statistically superior to a single domain model in explaining KD for low molecular weight PAHs, whereas the opposite was observed for high molecular weight PAHs. Because particularly the 4-ring PAHs are bioavailable and relevant from a risk assessment perspective and because their fast desorbing fractions correlate best with RC, we recommend RC as a relevant characteristic for river sediments.
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Affiliation(s)
- Anton Poot
- Aquatic Ecology and Water Quality Management Group, Department of Environmental Sciences, Wageningen University, P.O. Box 47, 6700 AA Wageningen, The Netherlands
| | - M T O Jonker
- Institute for Risk Assessment Sciences (IRAS), Utrecht University, P.O. Box 80177, 3508 TD Utrecht, The Netherlands
| | - Frits Gillissen
- Aquatic Ecology and Water Quality Management Group, Department of Environmental Sciences, Wageningen University, P.O. Box 47, 6700 AA Wageningen, The Netherlands
| | - Albert A Koelmans
- Aquatic Ecology and Water Quality Management Group, Department of Environmental Sciences, Wageningen University, P.O. Box 47, 6700 AA Wageningen, The Netherlands; IMARES - Institute for Marine Resources & Ecosystem Studies, Wageningen UR, P.O. Box 68, 1970 AB IJmuiden, The Netherlands.
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54
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Mayer P, Parkerton TF, Adams RG, Cargill JG, Gan J, Gouin T, Gschwend PM, Hawthorne SB, Helm P, Witt G, You J, Escher BI. Passive sampling methods for contaminated sediments: scientific rationale supporting use of freely dissolved concentrations. INTEGRATED ENVIRONMENTAL ASSESSMENT AND MANAGEMENT 2014; 10:197-209. [PMID: 24288295 PMCID: PMC4235458 DOI: 10.1002/ieam.1508] [Citation(s) in RCA: 135] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Revised: 09/16/2013] [Accepted: 11/26/2013] [Indexed: 05/17/2023]
Abstract
Passive sampling methods (PSMs) allow the quantification of the freely dissolved concentration (Cfree ) of an organic contaminant even in complex matrices such as sediments. Cfree is directly related to a contaminant's chemical activity, which drives spontaneous processes including diffusive uptake into benthic organisms and exchange with the overlying water column. Consequently, Cfree provides a more relevant dose metric than total sediment concentration. Recent developments in PSMs have significantly improved our ability to reliably measure even very low levels of Cfree . Application of PSMs in sediments is preferably conducted in the equilibrium regime, where freely dissolved concentrations in the sediment are well-linked to the measured concentration in the sampler via analyte-specific partition ratios. The equilibrium condition can then be assured by measuring a time series or a single time point using passive samplers with different surface to volume ratios. Sampling in the kinetic regime is also possible and generally involves the application of performance reference compounds for the calibration. Based on previous research on hydrophobic organic contaminants, it is concluded that Cfree allows a direct assessment of 1) contaminant exchange and equilibrium status between sediment and overlying water, 2) benthic bioaccumulation, and 3) potential toxicity to benthic organisms. Thus, the use of PSMs to measure Cfree provides an improved basis for the mechanistic understanding of fate and transport processes in sediments and has the potential to significantly improve risk assessment and management of contaminated sediments.
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Affiliation(s)
- Philipp Mayer
- Department of Environmental Science, Faculty of Science and Technology, Aarhus UniversityRoskilde, Denmark
- Present address is Department of Environmental Engineering, Technical University of DenmarkKongens Lyngby, Denmark
| | | | - Rachel G Adams
- Department of Civil Engineering and Environmental Science, Loyola Marymount UniversityLos Angeles, California, USA
| | - John G Cargill
- Delaware Department of Natural Resources and Environmental Control (DNREC)New Castle, Delaware, USA
| | - Jay Gan
- Department of Environmental Sciences, University of CaliforniaRiverside, California, USA
| | - Todd Gouin
- Unilever, Safety and Environmental Assurance Centre, Colworth Science ParkSharnbrook, United Kingdom
| | - Philip M Gschwend
- Civil and Environmental Engineering, Massachusetts Institute of TechnologyCambridge, Massachusetts, USA
| | - Steven B Hawthorne
- Energy and Environmental Research Center, University of North DakotaGrand Forks, North Dakota, USA
| | - Paul Helm
- Environmental Monitoring & Reporting Branch, Ontario Ministry of the EnvironmentToronto, Ontario, Canada
| | - Gesine Witt
- University of Applied Sciences HamburgHamburg, Germany
| | - Jing You
- State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of SciencesGuangzhou, Guangdong, China
| | - Beate I Escher
- The University of Queensland, National Research Centre for Environmental Toxicology (Entox)Brisbane, Australia
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55
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Rakowska MI, Kupryianchyk D, Smit MPJ, Koelmans AA, Grotenhuis JTC, Rijnaarts HHM. Kinetics of hydrophobic organic contaminant extraction from sediment by granular activated carbon. WATER RESEARCH 2014; 51:86-95. [PMID: 24397912 DOI: 10.1016/j.watres.2013.12.025] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Revised: 12/11/2013] [Accepted: 12/17/2013] [Indexed: 06/03/2023]
Abstract
Ex situ solid phase extraction with granular activated carbon (GAC) is a promising technique to remediate contaminated sediments. The methods' efficiency depends on the rate by which contaminants are transferred from the sediment to the surface of GAC. Here, we derive kinetic parameters for extraction of polycyclic aromatic hydrocarbons (PAH) from sediment by GAC, using a first-order multi-compartment kinetic model. The parameters were obtained by modeling sediment-GAC exchange kinetic data following a tiered model calibration approach. First, parameters for PAH desorption from sediment were calibrated using data from systems with 50% (by weight) GAC acting as an infinite sink. Second, the estimated parameters were used as fixed input to obtain GAC uptake kinetic parameters in sediment slurries with 4% GAC, representing the ex situ remediation scenario. PAH uptake rate constants (kGAC) by GAC ranged from 0.44 to 0.0005 d(-1), whereas GAC sorption coefficients (KGAC) ranged from 10(5.57) to 10(8.57) L kg(-1). These values are the first provided for GAC in the presence of sediment and show that ex situ extraction with GAC is sufficiently fast and effective to reduce the risks of the most available PAHs among those studied, such as fluorene, phenanthrene and anthracene.
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Affiliation(s)
- M I Rakowska
- Subdepartment of Environmental Technology, Department of Agrotechnology and Food Science, Wageningen University, P.O. Box 17, 6700 AA Wageningen, The Netherlands.
| | - D Kupryianchyk
- Aquatic Ecology and Water Quality Management Group, Department of Environmental Sciences, Wageningen University, P.O. Box 47, 6700 AA Wageningen, The Netherlands
| | - M P J Smit
- Subdepartment of Environmental Technology, Department of Agrotechnology and Food Science, Wageningen University, P.O. Box 17, 6700 AA Wageningen, The Netherlands
| | - A A Koelmans
- Aquatic Ecology and Water Quality Management Group, Department of Environmental Sciences, Wageningen University, P.O. Box 47, 6700 AA Wageningen, The Netherlands; IMARES - Institute for Marine Resources & Ecosystem Studies, Wageningen UR, P.O. Box 68, 1970 AB IJmuiden, The Netherlands
| | - J T C Grotenhuis
- Subdepartment of Environmental Technology, Department of Agrotechnology and Food Science, Wageningen University, P.O. Box 17, 6700 AA Wageningen, The Netherlands
| | - H H M Rijnaarts
- Subdepartment of Environmental Technology, Department of Agrotechnology and Food Science, Wageningen University, P.O. Box 17, 6700 AA Wageningen, The Netherlands
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56
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Wang F, Ji R, Jiang Z, Chen W. Species-dependent effects of biochar amendment on bioaccumulation of atrazine in earthworms. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2014; 186:241-247. [PMID: 24406324 DOI: 10.1016/j.envpol.2013.12.012] [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: 09/30/2013] [Revised: 12/14/2013] [Accepted: 12/15/2013] [Indexed: 06/03/2023]
Abstract
We observed that at a contamination level of 4.25 mg-atrazine/kg-soil, the biota-soil accumulation factor (BSAF) for the anecic M. guillelmi is approximately 5 times that for the epigeic E. foetida. This is attributable to the fact that bio-uptake by E. foetida is mainly through dermal absorption, whereas bio-uptake by M. guillelmi is largely affected by the gut processes, through which the physical grinding and surfactant-like materials facilitate the desorption of atrazine from soil. Strikingly, biochar amendment resulted in much greater reduction in BSAF for M. guillelmi than for E. foetida. At a biochar dose of 0.5% (wt:wt) the difference in BSAF between the two species became much smaller, and at a dose of 2% no statistical difference was observed. A likely explanation is that gut processes by M. guillelmi were much less effective in extracting atrazine from the biochar (the predominant phase wherein atrazine resided) than from soil particles.
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Affiliation(s)
- Fang Wang
- College of Environmental Science and Engineering, Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, Tianjin 300071, China
| | - Rong Ji
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China
| | - Zhongwei Jiang
- College of Environmental Science and Engineering, Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, Tianjin 300071, China; State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China
| | - Wei Chen
- College of Environmental Science and Engineering, Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, Tianjin 300071, China.
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57
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Oleszczuk P, Zielińska A, Cornelissen G. Stabilization of sewage sludge by different biochars towards reducing freely dissolved polycyclic aromatic hydrocarbons (PAHs) content. BIORESOURCE TECHNOLOGY 2014; 156:139-145. [PMID: 24495539 DOI: 10.1016/j.biortech.2014.01.003] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Revised: 12/29/2013] [Accepted: 01/02/2014] [Indexed: 06/03/2023]
Abstract
The objective of the study was to identify the effect of various biochars on the content of freely dissolved (Cfree) PAHs in sewage sludge. Apart from the evaluation of biochars obtained from various materials, the study also included the determination of the effects of biochar particle sizes and biochar production temperature on their ability to bind PAHs in sewage sludge. Increase in biochar dose caused a gradual reduction of Cfree PAHs content, but only up to the biochar dose of 5%. Depending on the kind of initial material from which the biochar was produced, the reduction of Cfree PAHs content in sewage sludge varied from 17.4% to 58.0%. Both the temperature and the particle size of biochar had an effect on PAH free concentration reduction. Biochars characterised by a low polarity index (O/C or (O+N)/C) reduced the level of Cfree PAHs better than biochars with a higher polarity index value.
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Affiliation(s)
- Patryk Oleszczuk
- Department of Environmental Chemistry, Maria Curie-Skłodowska University, 3 Maria Curie-Skłodowska Square, 20-031 Lublin, Poland.
| | - Anna Zielińska
- Department of Environmental Chemistry, Maria Curie-Skłodowska University, 3 Maria Curie-Skłodowska Square, 20-031 Lublin, Poland
| | - Gerard Cornelissen
- Department of Environmental Engineering, Norwegian Geotechnical Institute NGI, Oslo 16, Norway; Department of Applied Environmental Sciences (ITM), Stockholm University, Stockholm, Sweden; Institute for Plant and Environmental Sciences, University of Life Sciences (UMB), 5003 Ås, Norway
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58
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Jonker MTO, van Mourik L. Exceptionally strong sorption of infochemicals to activated carbon reduces their bioavailability to fish. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2014; 33:493-499. [PMID: 24272993 DOI: 10.1002/etc.2464] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 08/27/2013] [Accepted: 11/05/2013] [Indexed: 06/02/2023]
Abstract
The addition of activated carbon (AC) to sediments is a relatively new approach to remediate contaminated sites. Activated carbon strongly sorbs hydrophobic organic contaminants, thereby reducing their bioavailability and uptake in organisms. Because of its high sorption capacity, AC might, however, also sorb other chemicals that are not contaminants but instead have ecological functions. Examples of such compounds are infochemicals or pheromones (i.e., compounds serving as chemical inter- and intraspecies information vectors). The present study investigated the sorption of 2 known infochemicals, hypoxanthine-3-N-oxide (H3NO) and pyridine-N-oxide (PNO), to 5 different powdered ACs. Sorption isotherms of these low-molecular-weight, polar fish kairomone substances appeared highly nonlinear, with logarithmic Freundlich sorption coefficients of up to 7.6. At physiologically relevant concentrations, sorption was up to 7 to 9 orders of magnitude stronger than expected on the basis of hydrophobic forces only (i.e., the compounds' log octanol-water partition coefficient, being approximately -1), indicating exceptionally strong binding to specific sites. This binding effectively reduced the bioavailability of H3NO to Sarasa goldfish, as was shown in a behavioral assay. The present study demonstrates the previously unrecognized potential of AC to sorb ecologically relevant chemicals. Whether this potential may lead to subtle, unwanted ecological effects in the field will have to be investigated in more detail during future research.
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Affiliation(s)
- Michiel T O Jonker
- Institute for Risk Assessment Sciences, Utrecht University, Utrecht, the Netherlands
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59
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Jia F, Gan J. Comparing black carbon types in sequestering polybrominated diphenyl ethers (PBDEs) in sediments. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2014; 184:131-7. [PMID: 24047549 PMCID: PMC3915297 DOI: 10.1016/j.envpol.2013.08.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 08/13/2013] [Accepted: 08/20/2013] [Indexed: 05/09/2023]
Abstract
Polybrominated diphenyl ethers (PBDEs) are widely found in sediments, especially congeners from the penta-BDE formula. Due to their strong affinity for black carbon (BC), bioavailability of PBDEs may be decreased in BC-amended sediments. In this study, we used a matrix-SPME method to measure the freely dissolved concentration (Cfree) of PBDEs as a parameter of their potential bioavailability and evaluated the differences among biochar, charcoal, and activated carbon. Activated carbon displayed a substantially greater sequestration capacity than biochar or charcoal. At 1% amendment rate in sediment with low organic carbon (OC) content (0.12%), Cfree of six PBDEs was reduced by 47.5-78.0%, 47.3-77.5%, and 94.1-98.3% with biochar, charcoal, and activated carbon, respectively, while the sequestration was more limited in sediment with high OC content (0.87%). Therefore, it is important to consider the type and properties of the BC and the sediment in BC-based remediation or mitigation.
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Affiliation(s)
- Fang Jia
- Department of Environmental Sciences, University of California, Riverside, CA 92521, USA.
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60
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Parks AN, Chandler GT, Portis LM, Sullivan JC, Perron MM, Cantwell MG, Burgess RM, Ho KT, Ferguson PL. Effects of single-walled carbon nanotubes on the bioavailability of PCBs in field-contaminated sediments. Nanotoxicology 2013; 8 Suppl 1:111-7. [DOI: 10.3109/17435390.2013.858794] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Ashley N. Parks
- Nicholas School of the Environment, Duke University, Durham, NC, USA,
| | - G. Thomas Chandler
- Arnold School of Public Health, University of South Carolina, Columbia, SC, USA,
| | - Lisa M. Portis
- U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory – Atlantic Ecology Division, Narragansett, RI, USA,
| | - Julia C. Sullivan
- U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory – Atlantic Ecology Division, Narragansett, RI, USA,
| | - Monique M. Perron
- U.S. Environmental Protection Agency, Office of Pesticides Program – Health Effects Division, Arlington, VA, USA,
| | - Mark G. Cantwell
- U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory – Atlantic Ecology Division, Narragansett, RI, USA,
| | - Robert M. Burgess
- U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory – Atlantic Ecology Division, Narragansett, RI, USA,
| | - Kay T. Ho
- U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory – Atlantic Ecology Division, Narragansett, RI, USA,
| | - P. Lee Ferguson
- Nicholas School of the Environment, Duke University, Durham, NC, USA,
- Department of Civil and Environmental Engineering, Duke University, Durham, NC, USA, and
- Center for Environmental Implications of NanoTechnologies, Duke University, Durham, NC, USA
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61
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Harmsen J, Naidu R. Bioavailability as a tool in site management. JOURNAL OF HAZARDOUS MATERIALS 2013; 261:840-6. [PMID: 23340403 DOI: 10.1016/j.jhazmat.2012.12.044] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Revised: 12/17/2012] [Accepted: 12/26/2012] [Indexed: 05/05/2023]
Abstract
Bioavailability can form the basis for describing potential risks that contaminants pose to the environment and human health, and for determining remedial options to reduce risks of contaminant dispersal and toxicity. In assessments of polluted sites, methods to measure bioavailability can lead to a realistic appraisal of the potential risks from exposure to contaminants. For remediation purposes the application of the principles of bioavailability can result in practices that reduce bioavailability and consequently the risk of contaminants. Moreover the costs of remediation can be reduced. Examples from projects with organic contaminants (PAHs, pesticides and PFOS) and heavy metals in The Netherlands, Mali, Mauretania, Australia and Taiwan are presented. It is shown that using bioavailability principles in risk-based approaches is an attractive option in terms of both cost and in situ management of contaminated sites. Regulatory and public acceptance is, however, still the Achilles heel of these new remediation strategies.
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Affiliation(s)
- Joop Harmsen
- Alterra, Wageningen UR, P.O. Box 47, 6700 AA Wageningen, The Netherlands.
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62
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Janssen EML, Beckingham BA. Biological responses to activated carbon amendments in sediment remediation. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:7595-607. [PMID: 23745511 DOI: 10.1021/es401142e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Sorbent amendment with activated carbon (AC) is a novel in situ management strategy for addressing human and ecological health risks posed by hydrophobic organic chemicals (HOCs) in sediments and soils. A large body of literature shows that AC amendments can reduce bioavailability of sediment-associated HOCs by more than 60-90%. Empirically derived biodynamic models can predict bioaccumulation in benthic invertebrates within a factor of 2, allowing for future scenarios under AC amendment to be estimated. Higher AC dose and smaller AC particle size further reduce bioaccumulation of HOCs but may induce stress in some organisms. Adverse ecotoxicity response to AC exposure was observed in one-fifth of 82 tests, including changes in growth, lipid content, behavior, and survival. Negative effects on individual species and benthic communities appear to depend on the characteristics of the sedimentary environment and the AC amendment strategy (e.g., dose and particle size). More research is needed to evaluate reproductive end points, bacterial communities, and plants, and to link species- and community-level responses to amendment. In general, the ability of AC to effectively limit the mobility of HOCs in aquatic environments may outshine potential negative secondary effects, and these outcomes must be held in comparison to traditional remediation approaches.
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Affiliation(s)
- Elisabeth M-L Janssen
- Institute of Biogeochemistry and Pollutant Dynamics, Swiss Federal Institute of Technology (ETH), Universitätsstrasse 16, 8092 Zürich, Switzerland.
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63
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Velzeboer I, Peeters ETHM, Koelmans AA. Multiwalled carbon nanotubes at environmentally relevant concentrations affect the composition of benthic communities. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:7475-7482. [PMID: 23713543 DOI: 10.1021/es400777j] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
To date, chronic effect studies with manufactured nanomaterials under field conditions are scarce. Here, we report in situ effects of 0, 0.002, 0.02, 0.2, and 2 g/kg multiwalled carbon nanotubes (MWCNTs) in sediment on the benthic community composition after 15 months of exposure. Effects observed after 15 months were compared to those observed after 3 months and to community effects of another carbonaceous material (activated carbon; AC), which was simultaneously tested in a parallel study. Redundancy analysis with variance partitioning revealed a total explained variance of 51.7% of the variation in community composition after 15 months, of which MWCNT dose explained a statistically significant 9.9%. By stepwise excluding the highest MWCNT concentrations in the statistical analyses, MWCNT effects were shown to be statistically significant already at the lowest dose investigated, which can be considered environmentally relevant. We conclude that despite prolonged aging, encapsulation, and burial, MWCNTs can affect the structure of natural benthic communities in the field. This effect was similar to that of AC observed in a parallel experiment, which however was applied at a 50 times higher maximum dose. This suggests that the benthic community was more sensitive to MWCNTs than to the bulk carbon material AC.
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Affiliation(s)
- I Velzeboer
- Aquatic Ecology and Water Quality Management Group, Wageningen University, P.O. Box 47, 6700 AA Wageningen, The Netherlands.
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64
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Beckingham B, Buys D, Vandewalker H, Ghosh U. Observations of limited secondary effects to benthic invertebrates and macrophytes with activated carbon amendment in river sediments. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2013; 32:1504-15. [PMID: 23554105 DOI: 10.1002/etc.2231] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Revised: 11/10/2012] [Accepted: 03/19/2013] [Indexed: 05/16/2023]
Abstract
Amendment of activated carbon to sediments has been shown to effectively reduce the bioavailability of hydrophobic organic contaminants, but concerns have been raised about the potential toxicological impacts of administering a strong sorbent into sediments. The present study provides a summary of several investigations carried out as part of a pilot-scale study in a river to understand the secondary effects of activated carbon added to reduce the bioavailability of sediment-associated polychlorinated biphenyls. While some previous laboratory amendment studies have found reduced lipid content in freshwater worms exposed to activated carbon-treated sediments, the authors did not observe an impact with fine-granular activated carbon-amended sediments aged in the field. Benthic community studies did not find differences between control and activated carbon-treated field sites over 3 yr of postapplication monitoring. Laboratory studies with submerged aquatic plants indicated reduced growth in sediments amended with ≥5% activated carbon, which was attributed to volume dilution of nutritional sediment or bulk density changes and was also observed when the sediment was amended with biochar and inert perlite. Since in situ sorbent amendment is likely to be implemented in depositional sediment environments, potential negative impacts will likely be short-term if the treated site is slowly covered with new sediment over time. Overall suitability of activated carbon amendment for a site will depend on balancing ecosystem and human health benefits from contaminant bioavailability reduction with any potential negative impacts expected under field conditions.
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Affiliation(s)
- Barbara Beckingham
- Department of Chemical, Biochemical, and Environmental Engineering, University of Maryland Baltimore County, Baltimore, Maryland, USA.
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65
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Kupryianchyk D, Noori A, Rakowska MI, Grotenhuis JTC, Koelmans AA. Bioturbation and dissolved organic matter enhance contaminant fluxes from sediment treated with powdered and granular activated carbon. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:5092-100. [PMID: 23590290 DOI: 10.1021/es3040297] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Sediment amendment with activated carbon (AC) is a promising technique for in situ sediment remediation. To date it is not clear whether this technique sufficiently reduces sediment-to-water fluxes of sediment-bound hydrophobic organic chemicals (HOCs) in the presence of bioturbators. Here, we report polychlorobiphenyl (PCB) pore water concentrations, fluxes, mass transfer coefficients, and survival data of two benthic species, for four treatments: no AC addition (control), powdered AC addition, granular AC addition and addition and subsequent removal of GAC (sediment stripping). AC addition decreased mass fluxes but increased apparent mass transfer coefficients because of dissolved organic carbon (DOC) facilitated transport across the benthic boundary layer (BBL). In turn, DOC concentrations depended on bioturbator activity which was high for the PAC tolerant species Asellus aquaticus and low for AC sensitive species Lumbriculus variegatus. A dual BBL resistance model combining AC effects on gradients, DOC facilitated transport and biodiffusion was evaluated against the data and showed how the type of resistance differs with treatment and chemical hydrophobicity. Data and simulations illustrate the complex interplay between AC and contaminant toxicity to benthic organisms and how differences in species tolerance affect mass fluxes from sediment to the water column.
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Affiliation(s)
- D Kupryianchyk
- Aquatic Ecology and Water Quality Management Group, Department of Environmental Sciences, Wageningen University, PO Box 47, 6700 AA Wageningen, The Netherlands
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66
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Kupryianchyk D, Rakowska MI, Roessink I, Reichman EP, Grotenhuis JTC, Koelmans AA. In situ treatment with activated carbon reduces bioaccumulation in aquatic food chains. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:4563-71. [PMID: 23544454 DOI: 10.1021/es305265x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
In situ activated carbon (AC) amendment is a new direction in contaminated sediment management, yet its effectiveness and safety have never been tested on the level of entire food chains including fish. Here we tested the effects of three different AC treatments on hydrophobic organic chemical (HOC) concentrations in pore water, benthic invertebrates, zooplankton, and fish (Leuciscus idus melanotus). AC treatments were mixing with powdered AC (PAC), mixing with granular AC (GAC), and addition-removal of GAC (sediment stripping). The AC treatments resulted in a significant decrease in HOC concentrations in pore water, benthic invertebrates, zooplankton, macrophytes, and fish. In 6 months, PAC treatment caused a reduction of accumulation of polychlorobiphenyls (PCB) in fish by a factor of 20, bringing pollutant levels below toxic thresholds. All AC treatments supported growth of fish, but growth was inhibited in the PAC treatment, which was likely explained by reduced nutrient concentrations, resulting in lower zooplankton (i.e., food) densities for the fish. PAC treatment may be advised for sites where immediate ecosystem protection is required. GAC treatment may be equally effective in the longer term and may be adequate for vulnerable ecosystems where longer-term protection suffices.
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Affiliation(s)
- D Kupryianchyk
- Aquatic Ecology and Water Quality Management Group, Department of Environmental Sciences, Wageningen University, P.O. Box 47, 6700 AA Wageningen, The Netherlands
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67
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Gomes HI, Dias-Ferreira C, Ribeiro AB. Overview of in situ and ex situ remediation technologies for PCB-contaminated soils and sediments and obstacles for full-scale application. THE SCIENCE OF THE TOTAL ENVIRONMENT 2013; 445-446:237-60. [PMID: 23334318 DOI: 10.1016/j.scitotenv.2012.11.098] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Revised: 11/28/2012] [Accepted: 11/28/2012] [Indexed: 05/21/2023]
Abstract
Polychlorinated biphenyls (PCB) are persistent organic pollutants used worldwide between the 1930s and 1980s. Although their use has been heavily restricted, PCB can be found in contaminated soils and sediments. The most frequent remediation solutions adopted are "dig and dump" and "dig and incinerate", but there are currently new methods that could be more sustainable alternatives. This paper takes a look into the remediation options available for PCB-contaminated soils and sediments, differentiating between biological, chemical, physical and thermal methods. The use of combined technologies was also reviewed. Most of them are still in an initial development stage and further research in different implementation issues is needed. There is no single technology that is the solution for PCB contamination problem. The successful remediation of a site will depend on proper selection, design and adjustment of the technology or combined technologies to the site characteristics.
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Affiliation(s)
- Helena I Gomes
- CENSE - Center for Environmental and Sustainability Research, Departamento de Ciências e Engenharia do Ambiente, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal.
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68
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Rakowska MI, Kupryianchyk D, Grotenhuis T, Rijnaarts HHM, Koelmans AA. Extraction of sediment-associated polycyclic aromatic hydrocarbons with granular activated carbon. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2013; 32:304-11. [PMID: 23147869 DOI: 10.1002/etc.2066] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Revised: 08/01/2012] [Accepted: 09/09/2012] [Indexed: 05/18/2023]
Abstract
Addition of activated carbon (AC) to sediments has been proposed as a method to reduce ecotoxicological risks of sediment-bound contaminants. The present study explores the effectiveness of granular AC (GAC) in extracting polycyclic aromatic hydrocarbon (PAH) from highly contaminated sediments. Four candidate GAC materials were screened in terms of PAH extraction efficiency using single-step 24-h GAC extractions, with traditional 24-h Tenax extraction as a reference. Subsequently, sorption of native PAHs to the best performing GAC 1240W (0.45-1.70 mm) was studied for sediment only and for GAC-sediment mixtures at different GAC-sediment weight ratios, using 76-µm polyoxymethylene (POM) passive samplers. Granular AC sorption parameters for PAHs were determined by subtracting the contribution of PAH sorption to sediment from PAH sorption to the GAC-sediment mixture. It appears that the binding of PAHs and the effectiveness of GAC to reduce sediment porewater concentrations were highly dependent on the GAC-sediment mixing ratio and hydrophobicity of the PAH. Despite the considerable fouling of GAC by organic matter and oil, 50 to 90% of the most available PAH was extracted by the GAC during a 28-d contact time, at a dose as low as 4%, which also is a feasible dose in field-scale applications aimed at cleaning the sediment by GAC addition and removal.
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Affiliation(s)
- M I Rakowska
- Subdepartment of Environmental Technology, Department of Agrotechnology and Food Science, Wageningen University, Wageningen, The Netherlands.
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69
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Kwadijk CJAF, Velzeboer I, Koelmans AA. Sorption of perfluorooctane sulfonate to carbon nanotubes in aquatic sediments. CHEMOSPHERE 2013; 90:1631-1636. [PMID: 23041036 DOI: 10.1016/j.chemosphere.2012.08.041] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Revised: 08/10/2012] [Accepted: 08/20/2012] [Indexed: 06/01/2023]
Abstract
To date, sorption of organic compounds to nanomaterials has mainly been studied for the nanomaterial in its pristine state. However, sorption may be different when nanomaterials are buried in sediments. Here, we studied sorption of Perfluorooctane sulfonate (PFOS) to sediment and to sediment with 4% multiwalled carbon nanotubes (MWCNTs), as a function of factors affecting PFOS sorption; aqueous concentration, pH and Ca(2+) concentration. Sorption to MWCNT in the sediment-MWCNT mixtures was assessed by subtracting the contribution of PFOS sorption to sediment-only from PFOS sorption to the total sediment-MWCNT mixture. PFOS Log K(D) values ranged 0.52-1.62 L kg(-1) for sediment and 1.91-2.90 L kg(-1) for MWCNT present in the sediment. The latter values are relatively low, which is attributed to fouling of MWCNT by sediment organic matter. PFOS sorption was near-linear for sediment (Freundlich exponent of 0.92 ± 0.063) but non-linear for MWCNT (Freundlich exponent of 0.66 ± 0.03). Consequently, the impact of MWCNT on sorption in the mixture was larger at low PFOS aqueous concentration. Effects of pH and Ca(2+) on PFOS sorption to MWCNT were statistically significant. We conclude that MWCNT fouling and PFOS concentration dependency are important factors affecting PFOS-MWCNT interactions in sediments.
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Affiliation(s)
- C J A F Kwadijk
- Institute for Marine Resources & Ecosystem Studies, Wageningen UR, 1970 AB IJmuiden, The Netherlands.
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70
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Nybom I, Werner D, Leppänen MT, Siavalas G, Christanis K, Karapanagioti HK, Kukkonen JVK, Akkanen J. Responses of Lumbriculus variegatus to activated carbon amendments in uncontaminated sediments. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2012; 46:12895-903. [PMID: 23153215 DOI: 10.1021/es303430j] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Activated carbon (AC) amendment is a recently developed sediment remediation method. The strong hydrophobic organic contaminant sorption efficiency of AC has been shown in several studies, but effects on benthic organisms require more investigation. The AC induced effects on egestion rate, growth and reproduction of Lumbriculus variegatus were studied by applying bituminous coal based AC in three different particle size fractions, namely <63 μm (90%, AC(p)), 63-200 μm (AC(m)) and 1000 μm (AC(g)), to natural uncontaminated (HS) and artificial sediment (AS). Egestion rate, growth and reproduction decreased with increasing AC concentration and finer AC particle fractions, effects being stronger on HS than on AS sediment. Lipid content in AS was reduced already at the lowest AC doses applied (AC(p) and AC(m) 0.05%, AC(g) 0.25%). In addition, hormesis-like response was observed in growth (AS) and reproduction (AS, HS) indicating that AC may disturb organisms even at very low doses. Potential ecological effects need to be further evaluated in an amendment- and site-specific manner.
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Affiliation(s)
- Inna Nybom
- Department of Biology, University of Eastern Finland (UEF), P.O. Box 111, FI-80101 Joensuu, Finland.
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71
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van Noort PCM, Koelmans AA. Nonequilibrium of organic compounds in sediment-water systems. Consequences for risk assessment and remediation measures. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2012; 46:10900-10908. [PMID: 22992173 DOI: 10.1021/es300630t] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
In many cases, sediment risk assessment, and remediation rely on the assumption of equilibrium between chemical concentrations in sediment pore water and overlying surface water and thus rely on pore water concentrations only and do not additionally include assessment of the overlying water concentration. Traditionally, the validity of this assumption was insufficiently documented due to a lack of data. Recent studies using passive samplers, however, provided sufficient data for the first systematic evaluation of the extent of disequilibrium between sediment pore water and overlying surface water. Recent bioaccumulation studies reveal uncertainty as to which of these concentrations govern bioaccumulation by benthic organisms. Here, we provide the first review of studies measuring disequilibrium identifying general patterns and implications for the aforementioned areas of application. In most studies on water/sediment (dis)equilibrium, sediment pore water and overlying surface water are close to equilibrium. For lower molecular weight PAHs, overlying water concentrations tended to be relative low, which is tentatively ascribed to biodegradation in the water column. Substantial nonequilibrium was observed at some hot-spot locations such as in semistagnant harbors. In such cases, efficacy of sediment remediation measures to improve overlying water quality can be questioned because differences between overlying water concentrations at the hot-spots and those at reference locations typically are small. For nonequilibrium situations and some benthic taxa, exposure may be determined best by pore water concentrations. Improving our understanding in this area may further improve risk assessment of contaminated sediments.
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Affiliation(s)
- P C M van Noort
- Aquatic Ecology and Water Quality Management Group, Wageningen University, PO Box 47, 6700 AA Wageningen, The Netherlands.
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Kupryianchyk D, Peeters ETHM, Rakowska MI, Reichman EP, Grotenhuis JTC, Koelmans AA. Long-term recovery of benthic communities in sediments amended with activated carbon. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2012; 46:10735-42. [PMID: 22934596 DOI: 10.1021/es302285h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Using activated carbon (AC) for sediment remediation may have negative effects on benthic communities. To date, most AC effect studies were short-term and limited to single species laboratory tests. Here, we studied the effects of AC on the recolonization of benthic communities. Sediment from an unpolluted site was amended with increasing levels of AC, placed in trays and randomly embedded in the original site, which acted as a donor system for recolonization of benthic species. After 3 and 15 months, the trays were retrieved and benthic organisms identified. A positive trend with AC was detected for species abundance after 3 months, whereas after 15 months a negative trend with AC was detected for Lumbriculidae and Pisidiidae. On the community level, statistical analyses showed a considerable recovery in terms of species diversity and abundance in 3 months and full recovery of the community after 15 months. This was explained from migration of individuals from the donor system, followed by further migration and reproduction of the species in the next year. AC treatments explained 3% of the variance in the community data. This work suggests that AC community effects are mild as long as AC levels are not too high (1-4%).
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Affiliation(s)
- D Kupryianchyk
- Aquatic Ecology and Water Quality Management Group, Department of Environmental Sciences, Wageningen University, P.O. Box 47, 6700 AA Wageningen, The Netherlands.
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Kupryianchyk D, Rakowska MI, Grotenhuis JTC, Koelmans AA. Modeling trade-off between PAH toxicity reduction and negative effects of sorbent amendments to contaminated sediments. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2012; 46:4975-4984. [PMID: 22420612 DOI: 10.1021/es2044954] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Adding activated carbon (AC) to contaminated sediment has been suggested as an effective method for sediment remediation. AC binds chemicals such as polycyclic aromatic hydrocarbons (PAHs), thus reducing the toxicity of the sediment. Negative effects of AC on benthic organisms have also been reported. Here, we present a conceptual model to quantify the trade-off, in terms of biomass changes, between the advantageous PAH toxicity reduction and the negative effects of AC on populations of benthic species. The model describes population growth, incorporates concentration-effect relationships for PAHs in the pore water and for AC, and uses an equilibrium sorption model to estimate PAH pore water concentrations as a function of AC dosage. We calibrated the model using bioassay data and analyzed it by calculating isoclines of zero population growth for two species. For the sediment evaluated here, the results show that AC may safely protect the benthic habitat against considerable sediment PAH concentrations as long as the AC dosage remains below 4%.
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Affiliation(s)
- D Kupryianchyk
- Aquatic Ecology and Water Quality Management Group, Department of Environmental Sciences, Wageningen University, P.O. Box 47, 6700 AA Wageningen, The Netherlands.
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