Modification of Saharan dust size distribution during its transport over the Anatolian Plateau.

Particle number size distribution in dust plumes and its modification as the plume travels over the Anatolia were investigated by measuring particle number size distributions at two stations: one located on the Mediterranean coast of Turkey and the other on the Anatolian plateau. Clustering of backtrajectories revealed six trajectory clusters at the Marmaris station and nine clusters at the Ankara station. Cluster 6 in Marmaris and clusters 6, 7 and 9 in Ankara stations had the potential to transport Saharan dust to stations. Concentration of particles with D ≤ 1 µm increased during dust events in the Ankara station, but decreased at the Marmaris station. Higher PM1 concentrations during the non-dust period at the Marmaris station were attributed to the dominance of secondary particle formation on PM1 concentrations. Occurrence of sea salt episodes at the Marmaris station and anthropogenic episodes at the Ankara station affects the distribution of episodes. If different types of episodes are not differentiated and all episodes are considered as dust, it can lead to misleadingly high dust episodes in winter. Six Saharan dust episodes were sequentially intercepted first at the Marmaris and then at the Ankara stations. These episodes were used to study how dust size distribution is modified as the plume travels from the Mediterranean coast to central Anatolia. On the average, travel time between the two stations is 1-2 days. Particle number concentrations in 1 µm ≤ D ≤ 110 µm size range were consistently high at the Ankara station, indicating that local sources play a role in modifying the number size distribution as the plume travels over the Anatolian plateau.

Microplastics and organics - A comparative study of sorption of triclosan and malachite green onto polyethylene.

This study aims to elucidate interaction of organics with microplastics in a comparative manner via the use of two model compounds (i.e., triclosan (TCS) and malachite green (MG)) having different physicochemical properties, onto polyethylene (PE). TCS, is hydrophobic with low solubility, while MG is hydrophilic with high aqueous solubility. Kinetic studies indicate faster sorption (teq = 24 h) and equilibrium studies show much higher capacity (qe = 6,921 µg/g) for TCS, when compared to those of MG (teq = 5 d, qe = 221 µg/g). While pseudo-kinetic model fits sorption of both organics to PE, equilibrium isotherms as well as the results on effect of particle size and pH indicate dissimilar sorption mechanisms. Considering pHPZC = 2, observation of favourable sorption of TCS in acidic regions and sorption being unaffected by particle size was explained by TCS sorption to be dominated by hydrophobic interactions in amorph regions of PE. Higher removal of MG was observed at lower surface charge of PE, and a clear favourable impact of surface area on MG sorptive capacity pointed to the presence of non-specific van der Waals type interactions on the surface of PE. Mechanistic evaluations presented here contribute to our understanding of interaction of MPs with organics in aquatic ecosystems.

Characterization and source apportionment of carbonaceous aerosols in fine particles at urban and suburban atmospheres of Ankara, Turkey.

In order to find the spatial distribution characteristics of elemental (EC) and organic (OC) carbon in fine particles, daily PM2.5 aerosol samples were collected at two different stations, between July 2014 and September 2015 in Ankara, Turkey. Concentrations of OC ranged from 2.1 to 42 µg m-3 at urban station. These concentrations were higher than those obtained for suburban station whose values ranged from 1.3 to 15 µg m-3. Concentrations of EC ranged from 0.7 to 4.9 µg m-3 at the urban station. As in OC case, the corresponding levels were higher than those measured for suburban station. The associated EC levels ranged from 0.1 to 3.4 µg m-3 for the suburban station. Daily changes in the levels of EC were larger than the OC levels. OC/EC ratios were lower with lower monthly variability in summer and higher with lower monthly variability in winter at the urban site. Medium and weak correlations were obtained between EC and OC in the winter and summer seasons, respectively, at both stations. Secondary organic carbon (SOC) was an important component of OC in PM2.5 at the urban and suburban sites. The winter SOC level was higher than the summer SOC level at the urban site but slightly lower than the summer SOC level at the suburban site. Total carbon was apportioned using factor analysis for the eight carbon fraction data (OC1, OC2, OC3, OC4, EC1, EC2, EC3, and OP). The main sources of pollutants in the urban and suburban settings were from vehicular emissions, biomass and coal combustions, and road dust.

Development of a fate and transport model for biodegradation of PBDE congeners in sediments.

Polybrominated diphenyl ethers (PBDEs) are a family where each congener possesses different physicochemical properties, persistence and/or toxicity. Biodegradation can selectively change the abundance of congeners. These warrant modeling of individual congeners by considering biodegradation pathways together with fate and transport (F&T) mechanisms. Accordingly, this study aims to develop a F&T model (Fate and Transport model for Hydrophobic Pollutants - FTHP) that integrates congener specific biodegradation of PBDEs in sediments. The model is tested using sediment data from a location representing the Lower South Bay of San Francisco. Results demonstrated settling, resuspension, and biodegradation as important mechanisms. FTHP is then used to predict congener concentrations in a period of 20 years for two cases (constant and time-dependent water column concentrations) and four alternative scenarios: no intervention (i.e., natural attenuation, also serves as the base case), no degradation, dredging and biostimulation. The greatest impact on the reduction of total PBDE concentrations was achieved by a reduction in water column concentrations, i.e. source control, and dredging. On the other hand, biostimulation coupled with source control was the most effective in reducing bioaccumulative PBDE congener concentrations and almost as effective as dredging for the rest of congeners. Proposed FTHP model can distinguish between congeners and help devise informed management plans which focus on decreasing risks associated with persistent and bioaccumulative compounds in contaminated sediments.

Assessment of PCB contamination, the potential for in situ microbial dechlorination and natural attenuation in an urban watershed at the East Coast of the United States.

Sediment contamination is a major environmental issue in many urban watersheds and coastal areas due to the potential toxic effects of contaminants on biota and human health. Characterizing and delineating areas of sediment contamination and toxicity are important goals of coastal resource management in terms of ecological and economical perspectives. Core and surficial sediment samples were collected from an industrialized urban watershed at the East Coast of the United Stated and analyzed to evaluate the PCB contamination profile and toxicity resulting from dioxin-like PCBs as well as reductive dechlorination potential of indigenous PCB halorespiring bacteria through dechlorination activity assays. To support the experimental results an anaerobic dechlorination model was applied to identify microbial dechlorination pathways. The total PCB concentration in core samples ranged from 3.9 to 225.6 ng/g·dry weight (dw) decreasing with depth compared to 353.2 to 1213.7 ng/g·dw in surficial samples. The results of this study indicated an increase in PCB contamination over the last century as the industrial activity intensified. The toxicity resulting from dioxin-like PCBs was reduced up to 94% in core samples via 21 pathways resulting from the dechlorination model. Dechlorination rates in surficial sediment were between 1.8 and 13.2 ·â€¯10-3 mol% PCB116/day, while lower rates occurred in the core sediment samples. Dechlorination was achieved mainly through meta followed by para dechlorination. However, the rarer ortho dechlorination was also observed. Detection of indigenous PCB dechlorinating bacteria in the sediments and reduction of toxicity indicated potential for natural attenuation when point and nonpoint source PCBs in the urban watershed are controlled and PCB loading reduced.

Levels of polybrominated diphenyl ethers and hexabromocyclododecane in treatment plant sludge: Implications on sludge management.

Past usage of polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCDD) in commercial products resulted in their continuous emission from sources. Wastewater treatment plants (WWTP) are the main sinks resulting from their industrial and domestic usage as well as atmospheric deposition. This preliminary study examined levels of PBDEs and HBCDD in urban and industrial WWTP sludge samples for the first time from Turkey. PBDE concentrations (sum of 26 congeners) of eight samples collected from four WWTPs were between 300 and 655 ng g-1 dw and 67-2.5*107 ng g-1 dw, and HBCDD concentrations (sum of α-, ß-, and γ- diastereoisomers) ranged 75-616 ng g-1 dw and 13-416 ng g-1 dw, for urban and industrial WWTP samples, respectively. Although PBDEs have never been produced in Turkey, the highest PBDE concentration in sewage sludge worldwide was identified in one of the WWTPs. PBDE and HBCDD levels in other sludge samples were comparable to those reported in the literature. Application of a chemical mass balance model (CMB) suggested: (i) the main source of PBDEs as deca-BDE mixture; (ii) influence of a background air PBDE profile for one of the industrial WWTPs, having low contamination; (iii) indoor dust PBDE contamination as another source for urban WWTPs. The preliminary results for BFR levels in Turkey were discussed in terms of sludge disposal methods used worldwide, and the need for regulatory limits for BFRs in sludge management.

Degradation of decabromodiphenyl ether (BDE-209) in microcosms mimicking sediment environment subjected to comparative bioremediation strategies.

The aim of this study was to examine bioremediation strategies for BDE-209 contaminated sediments. Sediment microcosms were established to observe anaerobic debromination of BDE-209 under conditions representing three bioremediation strategies: biostimulation, bioaugmentation and natural attenuation. To simulate biostimulation, a defined mineral medium containing both a carbon source (sodium formate) and electron donor (ethanol) was added into sediments. Bioaugmentation was established by enrichment of the sediments using a culture of Dehalobium chlorocoercia strain DF-1, previously shown to dechlorinate polychlorinated biphenyls, to sediments. No amendments were made to the third set in order to represent natural attenuation. The biostimulation, bioaugmentation and natural attenuation strategies resulted in 55.3%, 40.2% and 30.9% reductions in BDE-209, respectively, after 180 days. Nona- through tri-BDEs were observed as products, with 17 PBDE congeners detected in 25 different proposed debromination pathways. At the end of the 180 day incubation period, the products for bioaugmentation, biostimulation and natural attenuation were tri-BDEs, tetra-BDEs and penta-BDEs, respectively. The proposed pathways revealed that meta- and ortho-Br removal were favored in sediments, and that debromination regiospecificity varied with each bioremediation strategy applied. Lastly, pseudo-first-order rate constants for BDE-209 reduction were calculated as 0.0049 d-1, 0.0028 d-1, 0.0025 d-1 for biostimulation, bioaugmentation and natural attenuation, respectively.

A comparative evaluation of anaerobic dechlorination of PCB-118 and Aroclor 1254 in sediment microcosms from three PCB-impacted environments.

Aroclor 1254 (A1254) is the most toxic commercial PCB mixture produced, primarily due to its relatively high concentrations of dioxin-like congeners. This study demonstrates a comparative evaluation of dechlorination of A1254 and PCB-118 by indigenous organohalide respiring bacteria enriched from three PCB impacted sites: Grasse River (GR), NY; Fox River (FR), WI; and Baltimore Harbor (BH), MD. PCB-118 dechlorination rates in GR, BH, and FR was 0.0308, 0.015, and 0.0006 Cl-/biphenyl/day, respectively. A1254 dechlorination rates in GR, FR, and BH were 0.0153, 0.0144, and 0.0048 Cl-/biphenyl/day, respectively. A1254 dechlorination was achieved through the removal of doubly-/singly-flanked chlorines in meta and para positions of mostly penta- followed by hexa- and hepta-chlorinated congeners by 88%, 69%, and 51% in GR, and 88%, 87%, and 83% in FR, respectively, while in BH mostly hepta- (70%) followed by hexa-chlorinated congeners (66%) were dechlorinated. A previously developed Anaerobic Dechlorination Model (ADM) quantified a total of 17 toxicity-related dechlorination pathways in all three sediment microcosms. The toxic equivalency of A1254 based on seven dioxin-like congeners decreased by about 53%, 45% and 21%, in GR, FR and BH microcosms, respectively. The dechlorination products were generally tetra- and tri-chlorinated congeners with unflanked chlorines, all of which is susceptible to further degradation by aerobic bacteria. Concerning the toxic congeners, ADM can be useful to initiate further research focusing on the stimulation of the toxicity reducing pathways for risk assessment and effective remediation strategies.

Estimation of Anaerobic Debromination Rate Constants of PBDE Pathways Using an Anaerobic Dehalogenation Model.

This study aims to estimate anaerobic debromination rate constants (km) of PBDE pathways using previously reported laboratory soil data. km values of pathways are estimated by modifying a previously developed model as Anaerobic Dehalogenation Model. Debromination activities published in the literature in terms of bromine substitutions as well as specific microorganisms and their combinations are used for identification of pathways. The range of estimated km values is between 0.0003 and 0.0241 d-1. The median and maximum of km values are found to be comparable to the few available biologically confirmed rate constants published in the literature. The estimated km values can be used as input to numerical fate and transport models for a better and more detailed investigation of the fate of individual PBDEs in contaminated sediments. Various remediation scenarios such as monitored natural attenuation or bioremediation with bioaugmentation can be handled in a more quantitative manner with the help of km estimated in this study.

Estimation of rate constants of PCB dechlorination reactions using an anaerobic dehalogenation model.

This study aims to estimate anaerobic dechlorination rate constants (km) of reactions of individual PCB congeners using data from four laboratory microcosms set up using sediment from Baltimore Harbor. Pathway km values are estimated by modifying a previously developed model as Anaerobic Dehalogenation Model (ADM) which can be applied to any halogenated hydrophobic organic (HOC). Improvements such as handling multiple dechlorination activities (DAs) and co-elution of congeners, incorporating constraints, using new goodness of fit evaluation led to an increase in accuracy, speed and flexibility of ADM. DAs published in the literature in terms of chlorine substitutions as well as specific microorganisms and their combinations are used for identification of pathways. The best fit explaining the congener pattern changes was found for pathways of Phylotype DEH10, which has the ability to remove doubly flanked chlorines in meta and para positions, para flanked chlorines in meta position. The range of estimated km values is between 0.0001-0.133d-1, the median of which is found to be comparable to the few available published biologically confirmed rate constants. Compound specific modelling studies such as that performed by ADM can enable monitoring and prediction of concentration changes as well as toxicity during bioremediation.

Potential risk reduction of Aroclor 1254 by microbial dechlorination in anaerobic Grasse River sediment microcosms.

Aroclor 1254 was the second most produced commercial PCB mixture and is found in soils, sediments and sewage throughout the globe. This commercial PCB mixture is considered particularly toxic because of the relatively high concentrations of congeners with dioxin-like properties. The potential for risk reduction by microbial reductive dechlorination of Aroclor 1254 (A1254) was investigated in sediment microcosms from Grasse River (GR), Massena, NY. The specificity of A1254 dechlorination was doubly- and singly-flanked chlorines in meta positions and to a less extent doubly-flanked para chlorines of 2345-substituted chlorobiphenyl rings. The average dechlorination rate of A1254 was 0.0153 Cl-/biphenyl/day, and dechlorination rates of single congeners ranged between 0.001 and 0.0074 Cl-/biphenyl/day. Potential risk associated with A1254 based on the toxic equivalency factors of the dioxin-like congeners was reduced by 83%. Additional potential risk associated with bioaccumulation in fish was reduced by 35% based on biota-sediment accumulation factor estimates for all detected congeners. Finally, the dechlorination end-products were tri- and tetra-chlorobiphenyls with unflanked chlorines, all of which are susceptible to further degradation by aerobic microorganisms. The combined results indicate that microbial reductive dechlorination has the potential for reducing risk associated with toxicity and bioaccumulation in fish in sites contaminated with A1254.

Positive Matrix Factorization dynamics in fingerprinting: A comparative study of PMF2 and EPA-PMF3 for source apportionment of sediment polychlorinated biphenyls.

Receptor models were typically used in air pollution studies and few publications are available for Positive Matrix Factorization (PMF) that consider the details of parameters and procedures in evaluating the trace organic pollutants in sediments. In this study, environmental fate and source composition of Lake Eymir sediments contaminated by polychlorinated biphenyls (PCBs) were explored by applying two PMF models, Paatero's PMF2 and United States Environmental Protection Agency's (US EPA) EPA-PMF3. PMF2 and EPA-PMF3 rely on different algorithms; Paatero's algorithm and multilinear engine algorithm, respectively. Here, the approaches of two PMF models were compared for the identification of PCB patterns taking into consideration the effects of various uncertainty matrices, residual matrices and goodness-of fit parameters. As a result of the study, it was understood that both models resolved five factors and indicated Clophen A60 as the source of PCBs. These results were consistent with the results resolved by Chemical Mass Balance model applied to the same data set in a previous study. However, source contributions identified by two models differed in quantity, but with similar patterns. This study indicates a way in understanding behavior, fate and global source of persistent organic pollutants in sediment by applying and comparing with a special data including high percentage of below detected value (38.2%) to understand the dynamics of PMF model parameters.

Evaluation of PCB dechlorination pathways in anaerobic sediment microcosms using an anaerobic dechlorination model.

A detailed quantitative analysis of anaerobic dechlorination (AD) pathways of polychlorinated biphenyls (PCBs) in sediment microcosms was performed by applying an anaerobic dechlorination model (ADM). The purpose of ADM is to systematically analyze changes in a contaminant profile that result from microbial reductive dechlorination according to empirically determined dechlorination pathways. In contrast to prior studies that utilized modeling tools to predict dechlorination pathways, ADM also provides quantification of individual pathways. As only microbial reductive dechlorination of PCBs occurred in the modeled laboratory microcosms, extensive analysis of AD pathways was possible without the complicating effect of concurrent physico-chemical or other weathering mechanisms. The results from this study showed: (1) ninety three AD pathways are active; (2) tetra- to hepta-chlorobiphenyl (CB) congeners were common intermediates in several AD pathways, penta-CBs being the most frequently observed; (3) the highest rates of dechlorination were for penta-CB homologs during the initial 185 days; (4) the dominant terminal products of AD were PCB 32(26-4), 49(24-25), 51(24-26), 52(25-25), 72(25-35), 73(26-35) and 100(246-24), (5) potential toxicity of the sediment was reduced. ADM serves as a powerful tool not only for a thorough analysis of AD pathways, but also for providing necessary input for numerical fate models (as a degradation term) that investigate dechlorination products or outcome of natural attenuation, or bioremediation/bioaugmentation of PCB-impacted sediments.

PCBs in sludge: development of a practical extraction procedure and its application in an urban water resource recovery facility.

Sludges originating from water resource recovery facilities act as a sink for various contaminants including polychlorinated biphenyls (PCBs). Investigation of such pollutants provides detailed information about the pollutant burden of the region from which incoming wastewater is derived. However, the current extraction methods for PCBs in wastewater and sludge are both time- and solvent-consuming. Therefore, the purposes of this study were to develop a practical PCB extraction procedure and to monitor PCB levels in sludge originating from an urban water resource recovery facility (WRRF). Procedure applicability was shown by comparing the extraction results of certified reference materials with that of Soxhlet and by checking surrogate recovery. Diethyl ether, hexane, and hexane:acetone mixture were evaluated as the PCB extraction solvent; hexane was the most efficient solvent with the recovery results (89 to 102%) in an acceptable range of 70 to 130%. The PCB concentrations of the WRRF sludges were in the range of 3.6 ± 0.3 to 64.4 ± 9.3 µg/kg dry matter.

Apportionment of PCB sources near a transformer maintenance and repair facility in Ankara, Turkey.

The concentration and major sources of polychlorinated biphenyls (PCBs) were evaluated in the sediments from a special environmental protection area located near a transformer maintenance and repair facility (TMRF) in Ankara, Turkey. ∑PCB concentrations analyzed on Aroclor and congener basis (seven indicator congeners) ranged from 0.1 to 84.2 and 0.1 to 21.7 ng/g dry weight, respectively. Results show that higher total PCB concentrations were localized around one of the drainage channels of the TMRF. Identity and contribution of PCB sources were predicted using a chemical mass balance (CMB) based receptor model. The CMB model typically identified Aroclor 1260, the PCB mixture frequently used in transformers, as the major PCB source confirming the effect of the TMRF on the area. Poor prediction of some sample congener profiles suggest presence of environmental degradation mechanisms such as volatilization and differential solubilization of lower chlorinated congeners from sediments.

Impact of PCB-118 and transformer oil toxicity on anaerobic digestion of sludge: anaerobic toxicity assay results.

In this study, possible toxicity of increasing doses of PCB-118 and transformer oil (TO) on anaerobic sludge digestion was investigated. For this purpose, five different sets of reactors were prepared in which four different PCB-118 concentration (1, 10, 20, and 30mgL(-1)) and three different TO concentration (0.38, 0.76, and 1.52gL(-1)) were applied. Throughout the study, biogas production and composition, pH, TS, VS, and COD as well as PCB concentration were monitored. Toxicity was investigated by anaerobic toxicity assay (ATA) evaluating the reduction in methane production. A notable inhibition was observed mostly in 30mgL(-1) PCB reactors. A negative influence of PCB-118 and TO was observed on COD and solids removal. A maximum of 26.5% PCB-118 removal was attained.

Levels, distribution, and sources of polychlorinated biphenyls in sediments of Lake Eymir, Turkey.

Little information is available on the occurrence and fate of persistent organic pollutants in lakes of Turkey. The present study was performed as a first step to assess the occurrence, spatial distribution, and potential sources of polychlorinated biphenyls (PCBs) in surface sediments of Lake Eymir located in a special protection area. Σ41PCB concentrations range from 1.09 to 2.33 ng g(-1) in 62 sediment samples collected from the lake. The spatial homogeneity of the PCBs along the whole lake suggests the resuspension or redistribution of historic PCB contamination. A chemical mass balance (CMB) receptor model was used to identify the possible sources of PCBs, for which a limited number of congeners are available for modeling purposes. Results indicated Clophen A60 to be the major PCB source in lake sediments. CMB analysis also showed the importance of a number of compounds used for the assessment of source contributions.

Levels and sources of polychlorinated biphenyls in Ankara creek sediments, Turkey.

The spatial distribution, degree of pollution and major sources of polychlorinated biphenyls (PCBs) were evaluated in surficial sediments of Ankara Creek, located in the capital of Turkey and serving as one of the tributaries in the third largest watershed in Turkey. Sediment ΣPCB concentrations analyzed on Aroclor and congener basis (seven indicator congeners) range from 5.5 to 777.6 ng g(-1) and 3.7 to 743.3 ng g(-1) dw as Aroclor and congener based concentrations, respectively. High concentrations of ΣPCBs were observed in the samples located at the downstream sections of the Creek, after discharge from Ankara municipal wastewater treatment plant. Using a chemical mass balance receptor model (CMB), major sources of PCBs affecting the sediments were investigated. The CMB model identified Aroclor 1254 and 1260 to be the major PCB sources affecting sediments. The potential sources for the PCBs were briefly discussed in terms of their use in various industrial applications.

A preliminary investigation of the environmental impact of a thermal power plant in relation to PCB contamination.

PURPOSE: The most significant application of polychlorinated biphenyls (PCBs) is in transformers and capacitors. Therefore, power plants are important suspected sources for entry of PCBs into the environment. In this context, the levels and distribution of PCBs in sediment, soil, ash, and sludge samples were investigated around Seyitömer thermal power plant, Kütahya, Turkey. Moreover, identity and contribution of PCB mixtures were predicted using the chemical mass balance (CMB) receptor model. METHODS: United States Environmental Protection Agency methods were applied during sample preparation, extraction (3540C), cleanup (3660B, 3665A, 3630C), and analysis (8082A). RESULTS: ΣPCB concentrations in the region ranged from not detected to 385 ng/g dry weight, with relatively higher contamination in sediments in comparison to soil, sludge, and ash samples collected from around the power plant. Congener profiles of the sediment and soil samples show penta-, hexa-, and hepta-chlorobiphenyls as the major homolog groups. The results from the CMB model indicate that PCB contamination is largely due to Clophen A60/A40 and Aroclor 1254/1254(late)/1260 release into the sediment and sludge samples around the thermal power plant. CONCLUSIONS: Since there are no other sources of PCBs in the region and the identity of PCB sources estimated by the CMB model mirrors PCB mixtures contained in transformers formerly used in the plant, the environmental contamination observed especially in sediments is attributed to the power plant. Release of PCBs over time, as indicated by the significant concentrations observed even in surface samples, emphasizes the importance of the need for better environmental management.

Assessment of temporal variation and sources of PCBs in the sediments of Mediterranean Sea, Mersin Bay, Turkey.

Information on temporal distribution of polychlorinated biphenyls (PCBs) in the coastal sediments of Mediterranean Sea, Mersin was compiled using data published between 1980 and 2009, and the present study. The first congener specific PCB results from the region yield concentration levels of Σ(41)PCBs in sediments ranging from 0.61 to 1.04 ng g(-1). Sediment profiles show penta-, hexa- and hepta-chlorobiphenyls, specifically, #149 and 153 as the most abundant congeners in all samples. Comparison of total PCB concentrations over time suggests no recent PCB input to the region. Using congener specific PCB data for the region, identity and contribution of PCB sources were also predicted using a chemical mass balance -based (CMB) receptor model. The CMB model identified Aroclor 1260 to be the major PCB source in coastal sediments. The potential sources for the PCBs were briefly discussed in terms of their use in various industrial applications.