Urban air PCDD/Fs: Dry deposition fluxes and mass transfer coefficients determined using a water surface sampler

Chemosphere 363 (2024) 142810 Contents lists available at ScienceDirect Chemosphere journal homepage: www.elsevier.com/locate/chemosphere Urban air PCDD/Fs: Dry deposition fluxes and mass transfer coefficients determined using a water surface sampler Abdul Alim Noori , Berke Gülegen , Yücel Tasdemir * Department of Environmental Engineering, Faculty of Engineering, Bursa Uludag University, 16059, Nilufer/Bursa, Turkey H I G H L I G H T S G R A P H I C A L A B S T R A C T • Direct dry deposition measurement of PCDD/Fs was achieved by employing a WSS. • Seasonal fluctuations of PCDD/Fs fluxes were observed depending on residential heating. • Gas phase PCDD/F fluxes were measured for the first time. • Simultaneously measured fluxes and concentrations were used to get MTCs of PCDD/Fs. • 4- and 5-chlorinated PCDD/Fs exhibited higher MTCs than 7- and 8-chlorinated ones. A R T I C L E I N F O A B S T R A C T Handling editor: R Ebinghaus Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) cause significant environmental concerns. Atmospheric PCDD/Fs permeate water bodies and other ecosystems through wet and dry deposition. In an urban site, dry deposition flux samples of gaseous phase PCDD/Fs were collected by a water surface sampler (WSS) operated between June 2022 and June 2023. There is a conspicuous absence of literature on the direct measurement of dry deposition flux levels in the gaseous phase of PCDD/Fs. In the study, PCDD/Fs in the gas phase reaching the WSS dissolved in the water according to Henry’s Law. The PCDD/Fs in the water were transferred to an XAD-2 resin column, sorbing the dissolved PCDD/Fs. The average monthly gas phase dry deposition flux was 34.07 ± 9.35 pg/m2-day (7.35 ± 2.16 pg I-TEQ/m2-day). The highest flux was measured in March (49.53 pg/m2-day), and the lowest was in August (18.64 pg/m2-day). These values indicated the direct flux from air to water. The atmospheric concentration of the gas-phase ranged from 68.38 to 126.88 fg/m3 (13.22–25.01 fg I-TEQ/m3). Dry deposition fluxes and concentrations of atmospheric PCDD/Fs were bigger in the colder months than in the warmer months. This was probably due to a significant increase in residential heating during the colder months, decreased photochemical reactions, and lower mixing heights. Regarding congeners in the dry deposition flux and concentration values in I-TEQ units, 2,3,7,8-TCDD compound predominated with the Keywords: Water surface sampler Direct flux measurement Air-water exchange POPs SVOCs * Corresponding author. E-mail address: tasdemir@uludag.edu.tr (Y. Tasdemir). https://doi.org/10.1016/j.chemosphere.2024.142810 Received 2 May 2024; Received in revised form 24 June 2024; Accepted 7 July 2024 Available online 8 July 2024 0045-6535/© 2024 Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies. A.A. Noori et al. Chemosphere 363 (2024) 142810 proportions of 31.61 ± 7.76% and 29.09 ± 12.34%, respectively. Concurrently measured dry deposition flux (Fg) and ambient air concentration (Cg) of PCDD/Fs were considered in the determination of mass transfer coefficient (MTC = Fg/Cg) calculation for each PCDD/F congener. The average MTC for targeted 17 PCDD/Fs was 0.45 ± 0.15 cm/s, and it fluctuated between 0.89 ± 0.30 cm/s for 2,3,7,8-TCDF and 0.2 ± 0.16 cm/s for OCDD. 1. Introduction speed, temperature, diffusion coefficients of gases, stability of the boundary layer, surface pollution level, turbulence at the air-water interface, and chemical reactions on the surface can introduce uncertainties in flux calculations as a function of the MTC (Jähne and Hauβecker, 1998). Therefore, accurate determination of the MTC is essential for a reliable assessment of air-water exchange fluxes. Within the scope of this study, our primary objectives can be presented as follows: (i) to measure the dry deposition fluxes of atmospheric PCDD/Fs in the gas phase with WSS, (ii) to examine fluctuations over time in the levels of dry deposition flux, (iii) to determine the MTCs of PCDD/F. Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are semi-volatile organic compounds (SVOCs) of substantial biological toxicity that are chemically stable and persistent in the environment (Lin et al., 2023). PCDD/Fs are teratogenic, mutagenic, and carcinogenic, posing significant risks to the environment and human health (Wei et al., 2022). The US EPA has reported that more than 90% of PCDD/Fs, a family of persistent organic pollutants (POPs), originate from human activities, primarily waste incineration and that their release into the environment can be minimized by implementing emission-reducing processes and techniques (Zhou et al., 2024). Atmospheric transport is an important path for the global distribution of SVOCs such as polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs) and PCDD/Fs. The atmospheric distribution of PCDD/Fs occurs through emissions resulting from industrial activities, energy production, combustion processes, waste incineration, and other human-sourced activities (Klima et al., 2020; Li et al., 2018; Song et al., 2023; Themba et al., 2023). These pollutants, in the gas and particle phases, are transported long distances under the effect of air currents. During this process, they are removed from the atmosphere by wet/dry deposition and photochemical reactions (Pan et al., 2021; Couvidat and Bessagnet, 2021; Knote et al., 2015; Chi et al., 2012; Schuhmacher et al., 2006). Atmospheric deposition and air-water exchange can be significant, particularly in urban/industrial areas located near bodies of water where ambient concentrations are high (Gigliotti et al., 2002; Khuman and Chakraborty, 2019; Pacyna, 2008; Totten et al., 2004). Generally, to measure the deposition flux of PCDD/Fs, stainless steel vessels, aqueous quadrangular vessels, smooth-surface plates, Bergerhoff, and wet/dry deposition samplers have been used (An Lieshout et al., 2001; Chi et al., 2009; Correa et al., 2006; Ogura et al., 2001a; Ren et al., 2007; Shih et al., 2006). The deposition fluxes of particulate phase PCDD/Fs were determined using the methods mentioned above, while there has been no value in the literature for the directly measured gas-phase PCDD/Fs. According to Schröder et al. (1997), the Bergerhoff method had minor importance due to the restricted collection of gases. On stainless steel and other smooth surfaces, uncertainties may emerge due to the re-evaporation of settled masses influenced by temperature and wind. Therefore, using water as the collection surface in dry deposition sampling can be beneficial because particles do not re-suspend once they settle on the water surface. The interactions between the gas-phase SVOCs and the water surface can be defined by Henry’s Law constants (Tasdemir and Holsen, 2006). The aerodynamically designed WSS has been successful in collecting the dry deposition fluxes of SVOCs in both particulate and gas phases (Chu et al., 2008; Cindoruk and Tasdemir, 2007, 2014; Eker and Tasdemir, 2018; Esen et al., 2010; Odabasi et al., 2001; Sakata et al., 2008; Sakata and Asakura, 2011; Sakin and Tasdemir, 2020; Seyfioglu and Odabasi, 2006; Shahin et al., 2002; Tasdemir et al., 2005; Tasdemir and Esen, 2007; Tasdemir and Holsen, 2006; Vardar et al., 2002). In this study, a modified WSS was employed for the gas phase dry deposition sampling of PCDD/Fs. The transition of pollutants between air and water depends on the concentration difference between the two media, the chemical properties of the compound, and atmospheric conditions (Rivero et al., 2020; Sakin and Tasdemir, 2020). The mass transfer coefficient (MTC) mathematically determines the exchange between these phases. The flux of pollutants in the gas phase can be calculated using the concentration difference between the two media and the MTC. Factors such as wind 2. Materials and method 2.1. Sampling procedure This investigation was done in Bursa, one of Turkey’s most populous cities, which accommodates an array of diverse industries, including automotive, textile, cement, paint, pharmaceutical, and food industries. Ambient air and dry deposition samples were collected from a site in the city center with heavy traffic between June 2022 and June 2023,. The samples were collected on the platform located in the garden of TUBİTAK BUTAL (Bursa Test and Analysis Laboratory) Directorate, at coordinates N 40◦ 11′54″, E 29◦ 02′55″ and approximately at an altitude of 2.5 m(Figure SM1). On non-rainy days, a modified WSS was used to collect dry deposition samples of PCDD/Fs. The WSS was made of stainless steel and all pipes were Teflon (Fig. 1). A 20 cm edge was placed in a steel pot to minimize the turbulence caused by the wind on top of the water in the tray (Tasdemir and Holsen, 2006). A tray, with a diameter of 60.5 cm and a depth of 0.5 cm, continuously maintained brimful with pure water, was situated at the top section of the sampler. This section brought air and water into contact to dissolve atmospheric PCDD/Fs in water. Thus, the air-water exchange occurred on this surface. The working principle of the WSS can be summarized as follows: The tray placed at the top of the WSS was constantly filled with water. Through a pump, pure water was continuously provided from the center of the tray, and this water was directed by being drained into a reservoir from four different points on the tray. The water exiting the reservoir has been passed through a filter to catch particles and through an XAD-2 resin column with a diameter of 2.5 cm and length of 40 cm to capture the PCDD/Fs dissolved in the water. This water, cleaned by passing through the filter and resin, was returned to the tray on top of the WSS using a pump. The average water flow rate was 345.0 ± 55.6 mL/min. The retention time of the water in the tray was kept at about 250 s. Thus, the re-evaporation of deposited PCDD/Fs into the air was minimized. In addition, wrapping the water reservoir and XAD-2 column with aluminum foil prevented the photochemical reaction-related degradations of the PCDD/Fs in the samples taken. Concurrently with the WSS, a high-volume air sampler (HVAS) (GPS11 Thermo Andersen, USA) was operated to determine the atmospheric concentrations of PCDD/Fs. The sampling time was approximately 48 h in both the WSS and HVAS. In each sampling period, the volume of air drawn by the HVAS had an average of 692.7 ± 188.3 m3. A glass fiber filter and polyurethane foams (PUFs) were used in the HVAS to sample the particulate and gas phase PCDD/Fs, respectively. On the dates of sampling, the meteorological parameters (temperature, wind speed, wind direction, relative humidity) at the sampling site were obtained from the General Directorate of Meteorology 2 A.A. Noori et al. Chemosphere 363 (2024) 142810 (Table SM1). The comprehensive TEQ content of PCDD/Fs was determined utilizing the International Toxic Equivalent Factor (ITEF) (Zhang et al., 2017). Prior to initiating the extraction process for actual samples and blanks, a volume of 100 μL of isotope-labeled standards, including OCDD (13C12, 99%), OCDF (13C12, 99%), 1,2,3,4,6,7,8-HpCDD (13C12, 99%), 1,2,3,4,6,7,8-HpCDF (13C12, 99%), 1,2,3,6,7,8-HxCDD (13C12, 99%), 2,3,4,6,7,8-HxCDF (13C12, 99%), 1,2,3,6,7,8-HxCDF (13C12, 99%), 1,2,3,4,7,8-HxCDD (13C12, 99%), 1,2,3,4,7,8-HxCDF (13C12, 99%), 1,2,3,7,8-PeCDD (13C12, 99%), 2,3,4,7,8-PeCDF (13C12, 99%), 2,3,7,8TCDD (13C12, 99%), and 2,3,7,8-TCDF (13C12, 99%), was added. The extraction process was carried out in a pressurized liquid extractor (PLE) system (from Fluid Management Systems, Inc.) using a mixture consisting of 50% dichloromethane (DCM) and 50% n-hexane (HEX) under high-pressure conditions (1700 PSI) and at elevated temperatures ranging from 85 to 120 ◦ C, completing approximately within 45 min. About 2 g of sodium sulfate was placed at the upper and lower sections of the extraction arm to isolate water in the WSS XAD-2 resin. 2.2. Analysis procedure In the pre-cleaning procedure, XAD-2 resin and PUF were subjected to a total of 48 h of Soxhlet extraction. The extraction consisted of a 24-h process in an acetone/hexane (ACE/HEX, 1:1) mixture and another 24-h process in a dichloromethane/petroleum ether (DCM/PE, 1:1) mixture. Thus, any potential organic pollutants that could be present in the XAD2 resin and PUFs were removed before sampling. The cleaned resin and PUFs were wrapped in aluminum foil, placed in a glass container, and stored in a deep freezer until sampling. On the other hand, filters used in the samplers were baked at above 450 ◦ C at least 2 h for pre-cleaning. Fig. 1. Side view of the water surface sampler. 3 A.A. Noori et al. Chemosphere 363 (2024) 142810 Following the extraction, the samples retained in the solvent were concentrated down to 0.5 mL through evaporation under a stream of nitrogen gas. To enhance efficiency, the samples contacting the vial’s sidewalls were washed three times with 5 mL n-hexane, after which the sample volume was brought back down to 0.5 mL. The samples were further processed through 6 cycles of ultrasonic cleaning, using a Bandelin Sonorex device, with 2 mL n-hexane until the volume reached 12 mL. Subsequent to the extraction, a cleaning step was performed using a PLE Cleanup device. This device utilized different solvent lines comprising 100% n-hexane, 2% DCM with 98% n-hexane, 50% ethyl acetate (EtAc) with 50% benzene, and 100% toluene. During the cleaning process, the sample was sequentially passed through a silica gel AP-145 kit, an alumina LP-121 kit, and a carbon CP-120 kit, all from Fluid Management Systems, Inc. Following this step, the samples held in the solvent were again reduced to 0.5 mL under a stream of nitrogen gas, washed three times with 5 mL n-hexane, and then dried entirely by nitrogen gas fumigation. Consequently, the samples were prepared and rendered suitable for analysis by GC-HRMS (Gas Chromatography-High Resolution Mass Spectrometry). 2.4. Quality assurance/quality control In order to ascertain any potential contamination that may occur from the inception of the sample collection process up to its read in the GC-HRMS, blank samples have been acquired (Caliskan et al., 2024; Eker Sanli and Tasdemir, 2023). The XAD-2 resin and PUF blank samples were delicately enveloped in aluminum foil and brought within a sealed vessel to the sampling location, where they were meticulously attached to the device. Subsequently, these samples were subjected to a 5-min pause on the apparatus, were again wrapped in aluminum foil and securely brought to the lab inside a closed glass vessel. Five blank samples of both the resin and PUFs were judiciously amassed. Blank sample rates averaged 1.85 ± 1.49% and 14.61 ± 2.82% of the amounts in the WSS and HVAS, respectively, relative to the amounts in the actual sample. The boundaries of instrument detection limits (IDLs) were established by employing a peak region that exhibited a signal-tonoise ratio of 3 at the lowest point on the standard calibration curve. The average IDL value of 1 μL injection for the PCDD/F compounds was approximately 0.35 pg. The limit of detection (LOD) was determined for each individual PCDD/F compound. The calculation of LOD was rendered as the mean blank mass plus three standard deviations. PCDD/Fs that exceed the LOD were considered. A separate LOD was established for each PCDD/F compound. The average blank quantities were subtracted from the amounts in the samples and a blank correction was executed. For ∑ 17PCDD/Fs the average LOD values in WSS and HVAS samples were 18.09 ± 4.23 pg/m2-day and 0.032 ± 0.003 pg/m3, respectively. The amounts of PCDD/F surpassing the LOD in the samples were acknowledged. Adjustments for blanks were applied by deducting the mean reference amounts from the quantities in the samples. The recovery rates varied between 50% and 120%. 2.3. GC-HRMS analysis Analyses of ambient air and dry deposition of PCDD/Fs were conducted consistent with the methodology outlined in USEPA 1613, utilizing an Agilent 7890B using GC-HRMS. Before the analysis, a volume correction standard containing 30 μL of 13C12-1,2,3,4-TCDD and 13C121,2,3,7,8,9-HxCDD compounds was added to the samples. Using this instrument, the 17 most toxic PCDD/F compounds including 2,3,7,8TCDF, 1,2,3,7,8-PeCDF, 2,3,4,7,8-PeCDF, 1,2,3,4,7,8-HxCDF, 1,2,3,6,7,8-HxCDF, 1,2,3,7,8,9-HxCDF, 2,3,4,6,7,8-HxCDF, 1,2,3,4,6,7,8-HpCDF, 1,2,3,4,7,8,9-HpCDF, OCDF, 2,3,7,8-TCDD, 1,2,3,7,8-PeCDD, 1,2,3,4,7,8-HxCDD, 1,2,3,6,7,8-HxCDD, 1,2,3,7,8,9HxCDD, 1,2,3,4,6,7,8-HpCDD and OCDD, were analyzed. Prior to performing the PCDD/F analyses, a calibration curve was constructed employing five distinct concentration levels (0.5, 2, 10, 40, 200 pg/mL) to ensure analytical accuracy. For each constituent, the r2 value of the calibration curve was ascertained to be greater than 0.999. The instrument’s performance was subsequently verified in conjunction with reading each ensemble of samples (n = 24), utilizing an intermediate calibrating standard (C = 10 pg/mL). Each sample was individually injected into the GC-HRMS in a volume of 1 μL. The analytical procedures were conducted utilizing an Agilent DB5-MS capillary column (60 m × 0.25 mm x 0.25 μm). The ion source and interface were adjusted to temperatures of 250 ◦ C and 275 ◦ C, respectively. Electron ionization mode was utilized with an ionization energy of 33.5 eV, and a trap current of 550 mA was employed. The instrument’s settings were modified to maintain a resolving power of 10000, with a 10% valley definition and a maximum resolution of 80000. The analysis of PCDD/F was conducted following the guidelines specified in the USEPA Method 1613 for PCDD/F determinations. Helium, with a purity of 99.999%, was employed as a carrier gas at a constant pressure of 25 PSI. The injector was operated at a temperature of 280 ◦ C in splitless mode, after which a purge process was implemented for 2 min. Initially, the oven was at a temperature of 110 ◦ C, subsequently escalating at a rate of 15 ◦ C per min until it reached a temperature of 220 ◦ C. The oven was maintained at this temperature for 10.67 min, after which the temperature was raised to 240 ◦ C at a rate of 1.5 ◦ C per min. An increment of 4 ◦ C per min elevated the temperature to 310 ◦ C, where it was sustained for 2 min. The determination of the targeted PCDD/F compounds was executed based on their retention times and qualifier ions. The measurement of PCDD/F compounds was performed through the utilization of an efficiency standard calibration. 3. Results and discussion 3.1. Atmospheric concentration of PCDD/Fs in the gas phase In this study, the monthly concentrations of Σ17PCDD/Fs in the gas phase ranged from 68.38 to 126.88 fg/m3 (average: 93.09 ± 17.62 fg/ m3), whereas its equivalent was between 13.22 and 25.01 fg I-TEQ/m3 (average 18.40 ± 3.84 fg I-TEQ/m3) (Fig. 2). The concentrations are detailed elsewhere (Gülegen, 2024) and comparisons with the literature gave reasonable results. For example, some ambient air values were reported to be between 37 and 81 fg/m3 (mean 48.5 fg/m3) in an urban area (Correa et al., 2006). In another study, the mean concentration of ∑ 17PCDD/F in the gas phase of samples taken from the surroundings of urban solid waste incineration facilities and traffic regions was 119.5 fg/m3 (Singh and Kulshrestha, 1997). However, the concentrations at the exit of a land tunnel were significantly higher, ranging from 715 to 765 fg/m3 (with an average of 742.32 fg/m3) (Deng et al., 2011). Incomplete combustion of fuels and heavy traffic, especially with vehicles using diesel fuel, caused the increased rates (Cheruiyot et al., 2016; Kim et al., 2003; Li et al., 2018; Wang et al., 2012). In this study, the total (particle + gas) average concentration of ∑ 3 17PCDD/Fs was determined as 445.79 ± 168.05 fg/m , with the proportion in the gas phase being 11.56 ± 17.27% (Gülegen, 2024). Similarly, Correa et al. (2006) reported a 2% gaseous phase in an industrial zone, while Castro-Jiménez et al. (2012) detected a 4% ratio in the North Italian Alps. However, Wu et al. (2009) identified as approximately 19.8% in the vicinity of a solid waste incineration facility. The concentration distribution of PCDD/Fs in the gas phase is illustrated in Fig. 3. Noticeably, measured in I-TEQ, the 2,3,7,8-TCDD and 2,3,4,7,8-PeCDF compounds have contributed the most significant proportions, standing at 29.00 ± 12.34% and 25.07 ± 6.99%, respectively. Conversely, the OCDD and OCDF presented the least additions, weighing in at 0.04 ± 0.02% and 0.01 ± 0.01%, respectively. It should 4 A.A. Noori et al. Chemosphere 363 (2024) 142810 Fig. 2. Dry deposition fluxes and concentrations of gas-phase 17PCDD/Fs. ∑ Fig. 3. Average PCDD/F compound values originated from flux and concentration samples. also be noted that the units are important for ordering the compounds because 2,3,4,7,8-PeCDF has the highest concentration in fg/m3 unit. In general, 4- and 5-chlorinated congeners were high in the gas phase concentrations. 2020). Even though dry deposition samples can be taken over different surfaces, there are advantages to utilizing water surfaces for determining dry deposition flux. Among the most significant advantages are that particles are captured by the water when they touch it and air/water exchange can be defined by Henry’s Law (Tasdemir and Holsen, 2006). In this study, the average gas phase dry deposition fluxes of ∑ 2 17PCDD/Fs was measured to be 34.07 ± 9.35 pg/m -day (7.35 ± 2.16 pg I-TEQ/m2day). The highest dry deposition flux value was observed in March, at 49.53 pg/m2day (11.42 pg I-TEQ/m2day) whereas the lowest was noted in August, standing at 18.64 pg/m2day (4.64 pg I- 3.2. Dry deposition fluxes of PCDD/Fs in the gas-phase This study employed a WSS to determine the dry deposition fluxes of PCDD/Fs in the gas phase. Dry deposition sampling of some SVOCs, including OCPs, PCBs, and PAHs was successfully carried out with WSS (Birgül et al., 2011; Eker and Tasdemir, 2018; Sakin and Tasdemir, 5 A.A. Noori et al. Chemosphere 363 (2024) 142810 TEQ/m2day) (Fig. 2). In this study, a general seasonal variation in flux values was observed. High values were apparent during the colder months while lower values were observed during the warmer periods. In their computational model-based research, Wu et al. (2009) estimated a minimum deposition of 5.07 pg I-TEQ/m2-day in July and a maximum of 26.1 pg I-TEQ/m2-day in January. In conjunction with this, Chi et al. (2012) have quantified dry deposition fluxes in a semi-rural area utilizing an automatic wet/dry sampler, measuring 3.72 pg I-TEQ/m2-day in the summer months (June–August) and 8.43 pg I-TEQ/m2-day during the winter months (December–February). The primary reasons for heightened emissions during colder months are the increased incidence of incomplete combustions in vehicle engines compared to warmer periods, the burning of fuels for residential and industrial heating purposes, the reduction in photochemical degradation with OH radicals in low temperatures, and the scarcity of thorough mixing and distribution during winter months (Brubaker and Hites, 1997; Chang et al., 2004; Chi et al., 2009; Deng et al., 2011). Thus, flux values also increase with increasing ambient PCDD/F concentrations. The flux values of PCDD/Fs depend on the sampling site characteristics and the measurement device employed (e.g., stainless steel containers, frisbee metal plates, greased surface plates, automatic wet/dry samplers, WSS, etc.), rendering a comparison of results across studies (Table 1). Moreover, fluctuations in the flux of pollutants can potentially be associated with variations in environmental concentrations and meteorological conditions, including temperature, relative humidity, wind speed, and atmospheric stability. Oka et al. (2006) conducted a study within the urban regions of Japan using a glass funnel for atmospheric bulk deposition of PCDD/Fs. The results, obtained between June and December, had an average value of 360 pg/m2-day. The bulk sampling method incorporated both dry deposition of the gas + particle phase and wet deposition observed with precipitation. Accordingly, the flux levels measured through bulk deposition are identified to be larger. Chi et al. (2012) reported the atmospheric dry deposition of gas + particle phase PCDD/Fs from three Taiwanese water reservoirs. Utilizing an automated wet/dry sampler, they quantified dry deposition levels between 0.38 and 4.55 pg I-TEQ/m2-day. The reduced dry deposition rate can be attributed to the spatial distance of the water reservoir from urban/traffic areas and emission sources. Ren et al. (2007) measured the atmospheric bulk deposition of PCDD/Fs in semi-urban, urban, and industrial regions of China’s Guangdong province sequentially 1900, 2200, and 2400 pg/m2-day, respectively. They stated that these values were very high due to exhaust gases from heavy traffic, burning of fossil fuels, and high combustion in industrial areas. Some researchers, on the other hand, have estimated the dry deposition flux by utilizing a model calculation (FT = VT x CT). In those calculations, atmospheric concentrations were measured yet the deposition velocities were taken from the literature (Suryani R. et al., 2015; Yu et al., 2021; Zhu et al., 2017). Mi et al. (2012) estimated the total deposition flux (gas + particle) of PCDD/Fs as 12.4–20.6 pg-I TEQ/m2-day in the industrial zone in Tainan, Taiwan, using VT = 0.42 cm/s and Vg = 0.01 cm/s deposition rates from the literature. In another study, Degrendele et al. (2020) estimated the dry deposition fluxes of particle-phase PCDD/Fs in the rural region of the Czech Republic, utilizing the deposition velocity in the literature, Vp = 0.2 cm/s; their results ranged from 1.15 to 1.56 pg WHO-TEQ/m2-day. In some studies by calculation method, dry deposition rates of PCDD/Fs in the gas phase have been estimated at 6–10% of the total flux (Huang et al., 2011; Suryani R. et al., 2015; Wang et al., 2010). 3.3. Profiles of PCDD/F congeners in gas-phase deposition fluxes The mean dry deposition fluxes of PCDD/F compounds measured throughout the sampling period are presented in Fig. 3. Upon investigation, 1,2,3,7,8-PeCDF had the highest value (5.49 ± 3.49 pg/m2-day) while the lowest compound, 2,3,4,6,7,8-HxCDF, was established at a Table 1 Literature comparison of dry deposition fluxes of PCDD/Fs. Region Country Sampling date Flux (pg- I-TEQ/m2-day) Method Reference Urban Manchester, UK Cardiff, UK Belgium Tokyo, Japan Yokohama, Japan Tsukuba, Japan Tanzawa, Japan Clinton Drive, US Lang Road, US South, Taiwan Guangzhou, China North, Taiwan 1991–1992 1420a** 1010a** 3.4–10aa 46.57a 30.14a 23.56a 15.62a 351b** 125b** 3.07–18.9b 1500–720aa 12.3–16.7b 2.07–9.9a 6.69–11.6b,c 5.73–15.6bc 0.38–4.55b 0.62–19.3a 12.4–20.6b,d 1.9bca 0.37bca 0.07–3.97e,a 0.12–12.13ea 1.15–1.56ea 6-19a** 4.64–11.42f Stainless Steel Pot Halsall et al. (1997) Bergerhoff Stainless Steel Pot An Lieshout et al. (2001) Ogura et al. (2001b) Automatic Wet/Dry Deposition Sampler Correa et al. (2006) Smooth Surface Plate Watery Rectangular Container Automatic Wet/Dry Deposition Sampler Shih et al. (2006) Ren et al. (2007) Chi et al. (2009) Calculation FT=Vp × Cp + Vg × Cg Wang et al. (2010) Automatic Wet/Dry Deposition Sampler Chi et al. (2012) Calculation FT=Vp × Cp + Vg × Cg Calculation FT=Vp × Cp + Vg × Cg Mi et al. (2012) Suryani R et al. (2015) Calculation Fp = Vp × Cp Castro-Jiménez et al. (2017) Calculation Fp = Vp × Cp Bergerhoff Water Surface Sampler Degrendele et al. (2020) Dreyer and Minkos (2023) This Study Industrial Urban Urban Semi-Urban Rural Industrial Urban Rural Urban Semi-Urban 1993–1999 1996–1998 2003–2004 2003–2004 2004–2005 2007–2008 Coastal Semi-Urban Reservoir Taiwan 2006 Taiwan 2008–2010 Industrial Coastal Background Coastal Coastal Background Background Urban + Traffic Tainan, Taiwan Hengchun, Taiwan Lulin, Taiwan Marseille, France Bizerte, Tunisia Czech Republic Germany Bursa, Turkey 2010–2011 2012–2013 2015–2016 2011–2014 2018–2019 2022–2023 pg WHO-TEQ/m2-day. pg/m2-day. Bulk. Gas + Particle. VT = 0,45-0,52-0,32-0,39 cm/s for the spring, summer, autumn and winter seasons respectively and Vg = 0,01 cm/s. VT = 0,42 cm/s and Vg = 0,01 cm/s. Vp = 0,2 cm/s. Gas-Phase. 6 A.A. Noori et al. Chemosphere 363 (2024) 142810 valuation of 0.29 ± 0.15 pg/m2-day (Fig. 3a). According to computations made per the I-TEQ unit, the maximum level for 2,3,7,8-TCDD was determined to be 2.36 ± 1.05 pg I-TEQ/m2-day, while the minimum value was identified for OCDF at 0.001 ± 0.001 pg I-TEQ/m2-day. Similarly, in a study, the highest and the lowest congeners in the gas phase fluxes were 2,3,7,8-TCDD and OCDF, respectively (Huang et al., 2011; Suryani R. et al., 2015). The 4- 5-chlorinated, and 7- 8-chlorinated congeners contributed to the total PCDD/F flux of 57.4% and 42.6%, respectively. The fluxes for high molecular weight PCDD/Fs were found to be minimal. Numerous observational studies have reported that 7and 8-chlorinated compounds predominantly exist in the particle phase (Mi et al., 2012; Wang et al., 2010; Wu et al., 2009). Dioxins and furans’ monthly calculated dry deposition flux percentages, alongside dry deposition flux percentages quantified in I-TEQ terms, are presented in Figure SM2. Based on collected data, the average percentage flux values for PCDFs and PCDDs were 61.48 ± 8.94% and 38.52 ± 8.94%, respectively. However, when evaluated in I-TEQ terms, the computed ratios for PCDD and PCDF were discerned as 58.29 ± 9.54% and 41.71 ± 9.54%, respectively (Figure SM2). The percentage contribution of the concentration and dry deposition ∑ ∑ of 7PCDD and 10PCDFs were calculated. Each compound’s flux and concentration values were divided by the total PCDD and PCDF values for that month to obtain the percentages of all compounds for each ∑ month (Figure SM3). 10PCDFs exhibited higher dry deposition flux, constituting 24.09 ± 12.08% for 1,2,3,7,8-PeCDF, while the lowest identified proportion was 1.33 ± 0.61% for the 2,3,4,6,7,8-HxCDF compounds. Calculations on an I-TEQ basis revealed that the 2,3,4,7,8-PeCDF compounds possessed the greatest proportion at 55.36 ± 10.88% yet the OCDF had the least percentage, registering at 0.02 ± ∑ 0.01%. In the dry deposition flux of the 7PCDDs currently under scrutiny, the compound 1,2,3,7,8-PeCDD held a preeminent proportion of almost 24.65% ± 7.78, whilst the compound 1,2,3,4,6,7,8-HpCDD sustained the minimum percentage of approximately 8.28% ± 4.78. As a result of the calculations performed in I-TEQ, the 2,3,7,8-TCDD had the highest rate of 54.84 ± 12.13% and the OCDD had the lowest rate of 0.03 ± 0.02% (Figure SM3). postulated that maintaining the minimal duration of water retention on the surface of the WSS ensures the lowest degree of re-evaporation of dissolved PCDD/Fs, thereby accepting that Cw(H/RT) is equivalent to zero. In this case, the equation simplifies to the following form: [ ] Fg = Kg Cg (2) In this study, the mass transfer coefficients of PCDD/Fs (Kg = Fg/Cg) were calculated by dividing the dry deposition flux (Fg) in the gas phase, directly measured by WSS, by the concentration in the gas phase (Cg), measured simultaneously by HVAS. As a result of the calculations, the ∑ average 17PCDD/F MTC values were determined as 0.45 ± 0.15 cm/s (Fig. 4). Due to the lack of MTCs of PCDD/Fs in the literature, the average MTC value calculated for PCDD/Fs was compared with the MTCs of SVOCs calculated using WSS (Table 2). Therefore, as shown in Table 2, the MTC values of PCDD/F measured by WSS are in harmony with those calculated for other SVOCs. Sheu (1996) used a smooth surface plate in the urban-industrial area of Taiwan and reported the MTCs of PAHs as 0.01 cm/s, below the value in this study. SVOCs may degrade and re-evaporate when exposed to atmospheric conditions and sunlight on smooth surfaces (Chi et al., 2009). Consequently, the quantity of gas-phase measurements on these surfaces appears to be minimal. Since the MTC is a function of the flux, the MTC values will also be low at relatively low fluxes. In the WSS, the masses collected were retained within an XAD-2 resin column. This resin column was wrapped in aluminum foil to protect it from the effects of sunlight. In determining MTCs, concentration, alongside meteorological parameters, can influence to a certain extent. A correlation analysis was conducted to establish the relationship between meteorological data (wind speed, temperature, and relative humidity) and MTCs. A significant relationship between the MTC and temperature was calculated (r = 0.8; p < 0.01), whereas no statistically significant relationship was found with other meteorological data and MTCs (p > 0.1). This result is similar to the ones reported for PCBs (Cindoruk and Tasdemir, 2007). The highest average MTC was calculated to be 0.89 ± 0.30 cm/s for 2,3,7,8-TCDF compound, while the lowest value was determined to be 0.2 ± 0.16 cm/s for OCDD compound (Table SM2). Due to the higher molecular weight of the 7- and 8-chlorinated PCDD/F compounds, their MTC values were lower than those of the lower-chlorinated PCDD/F compounds. Equation (2) shows that it is mathematically obvious that the slope obtained from the regression calculation of concentrations against the fluxes of PCDD/Fs in the gas phase will give the MTC (Kg) value (Fig. 5). The slope obtained as a result of the regression analysis has been calculated to be 308.97 m/day or 0.36 cm/s (r = 0.57; p < 0.001). The relationship between gas phase concentration and dry deposition fluxes was found to be statistically significant (Fig. 5). Of course, some factors affect fluxes and MTCs, causing fluctuations from linearity. Similarly, Odabasi et al. (2001) reported that the slope obtained from the relationship between gas phase flux and concentration in PAHs was 0.36 cm/s (r2 = 0.76; p < 0.05). 3.4. Mass transfer coefficients (MTCs) of PCDD/Fs The magnitude of gas transfer is contingent upon the concentration discrepancies between the atmosphere and water, the chemical properties of the compounds, and atmospheric conditions (Cindoruk and Tasdemir, 2007; Pryor et al., 2015). The transition at the air-water interface can be elucidated in a diffusion process encompassed within two film models. The two-film theory is employed for the estimation of mass transfer coefficients. The gaseous transition at the air-water interface is influenced by factors such as diffusion coefficients, wind velocity, temperature, stability of the boundary layer, surface contamination and chemical reactions occurring at the surface (Asman et al., 2003; Odabasi et al., 2001). Investigations reveal that the 2-film theory is effective in explaining the transfer of SVOCs to water surfaces and is given below (Silsby et al., 2021; Sobotka et al., 2022; Wang et al., 2018; Rasiq et al., 2019): [ ] H Fg = Kg Cg − (Cw ) (1) R×T 4. Conclusion There is no generally accepted dry deposition sampling method for PCDD/Fs. This research demonstrated that the WSS possesses the capability to sample the fluxes of PCDD/Fs effectively. The flux of PCDD/Fs in the gas phase (Fg) ranged between 49.53 and 18.64 pg/m2day. The fluxes in the literature reported the exchange level between air and water surfaces. Owing to the absence of direct measurements of dry deposition fluxes of PCDD/Fs in the gas phase previously, the flux data obtained in this study were compared with PCDD/F values determined via computational methods and bulk samplers. Consistent with the literature, the determined values of dry deposition fluxes exceed the data obtained in semi-rural, yet they were lower than those in industrial regions. where, Fg represents the net flux in the gas phase (pg/m2-day), Kg refers to the mass transfer coefficient (MTC) (m/day), Cg signifies the pollutant concentration in the gas phase (pg/m3), Cw denotes the pollutant concentration in the water (pg/m3), R is the universal gas constant (0.082 atm-L/mol-K), while T stands for the ambient temperature (K), and H typifies Henry’s constant (atm-L/mol). The MTC values of SVOCs have been determined by some researchers using directly measured dry deposition fluxes and concentration in air (Eker andTasdemir and Esen, 2008; Esen et al., 2010; Sakin and Tasdemir, 2020). In this equation, it is 7 A.A. Noori et al. Chemosphere 363 (2024) 142810 Fig. 4. Average mass transfer coefficients (MTCs) for each PCDD/F congener. Table 2 Mass transfer coefficients (MTCs) of some semi-volatile organic compounds (SVOCs). Region Country Sampling date Method SVOCs MTCs (cm/s) Reference Urban-Industrial Rural Urban Urban Urban Urban Urban Coastal Semi-Urban Urban + Traffic Semi-Urban Semi-Urban Semi-Rural Semi-Urban Urban + Traffic Tainan, Taiwan USA Chicago, USA Chicago, USA İzmir, Turkey Chicago, USA Chicago, USA İzmir, Turkey Bursa, Turkey Bursa, Turkey Bursa, Turkey Bursa, Turkey Bursa, Turkey Bursa, Turkey Bursa, Turkey 1994 1984 1995 1995 2003–2004 1995 1995 2005 2004–2005 2004–2005 2004–2005 2008–2009 2008–2009 2013 2022–2023 Smooth Surface Plate Mass Balance Water Surface Sampler Water Surface Sampler Water Surface Sampler Water Surface Sampler Water Surface Sampler Gas Stripping Water Surface Sampler Water Surface Sampler Water Surface Sampler Automatic Wet/Dry Deposition Sampler Water Surface Sampler Water Surface Sampler Water Surface Sampler PAH PAH PAH PCB HCHO PCB PCB PBDE PCB PAH PAH PAH OCP PCB PCDD/F 0.01 0.054 0.74 ± 0.52 0.54 ± 0.47 0.58 ± 0.21 0.40 ± 0.36 0.54 ± 0.47 0.25 0.6 ± 0.2 0.38 ± 0.17 0.69 ± 0.41 0.61 ± 0.11 0.46 ± 0.37 0.25 ± 0.23 0.45 ± 0.15 (Sheu, 1996) McVeety and Hites (1988) Odabasi et al. (2001) Tasdemir et al. (2005) Seyfioglu and Odabasi (2006) Tasdemir and Holsen (2006) Tasdemir et al. (2007) Cetin and Odabasi (2007) Cindoruk and Tasdemir (2007) Tasdemir and Esen (2008) Esen et al. (2010) Birgul (2013) Eker and Tasdemir (2018) Sakin and Tasdemir (2020) This Study CRediT authorship contribution statement A HVAS was utilized to measure the concentrations of PCDD/Fs in the ambient air. Concurrently, this HVAS was operated in conjunction with the WSS. The average concentration of PCDD/Fs in the gas phase (Cg) was determined to be 93.09 ± 17.62 fg/m3 (18.40 ± 3.84 fg I-TEQ/ m3). These values were comparable to the outcomes of investigations carried out in urban and traffic areas but they were below those reported in a study conducted in a highway tunnel. For each PCDD/F, the mass transfer coefficient (MTC) value was determined by the ratio of concurrently measured gas phase flux (Fg) and the concentration (Cg). The average MTC value for 17 PCDD/Fs congeners was 0.45 ± 0.15 cm/s. The calculated MTC values for PCDD/ Fs were found to be at a similar level compared to those obtained for SVOCs gathered via the WSS. The correlations between MTC values and meteorological data yielded significant results with respect to ambient temperature while demonstrating weak associations with other parameters. Abdul Alim Noori: Writing – original draft, Validation, Software, Methodology, Formal analysis, Data curation. Berke Gülegen: Writing – original draft, Visualization, Validation, Software, Methodology, Formal analysis, Data curation. Yücel Tasdemir: Writing – review & editing, Visualization, Supervision, Resources, Project administration, Investigation, Funding acquisition, Conceptualization. Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. 8 A.A. Noori et al. Chemosphere 363 (2024) 142810 Cetin, B., Odabasi, M., 2007. Air-water exchange and dry deposition of polybrominated diphenyl ethers at a coastal site in Izmir Bay, Turkey. Environ. Sci. Technol. 41, 785–791. https://doi.org/10.1021/es061368k. Chang, M.B., Chi, K.H., Chang, S.H., Chen, Y.W., 2004. Measurement of PCDD/F congener distributions in MWI stack gas and ambient air in northern Taiwan. Atmos. Environ. 38, 2535–2544. https://doi.org/10.1016/j.atmosenv.2004.01.037. Cheruiyot, N.K., Lee, W.-J., Yan, P., Mwangi, J.K., Wang, L.-C., Gao, X., Lin, N.-H., Chang-Chien, G.-P., 2016. An overview of PCDD/F inventories and emission factors from stationary and mobile sources: what we know and what is missing. Aerosol Air Qual. Res. 16, 2965–2988. https://doi.org/10.4209/aaqr.2016.10.0447. Chi, K.H., Kao, S.J., Liu, K.T., Lee, T.Y., 2012. Evaluation of atmospheric PCDD/F depositions via automated and traditional water surface samplers in Taiwan. Environ. Sci. Technol. 46, 2839–2846. https://doi.org/10.1021/es204230p. Chi, K.H., Liu, K.T., Chang, S.H., Chang, M.B., 2009. Atmospheric deposition of PCDD/Fs measured via automated and traditional samplers in Northern Taiwan. Chemosphere 77, 1184–1190. https://doi.org/10.1016/j.chemosphere.2009.09.027. Chu, C.C., Fang, G.C., Chen, J.C., Yang, I.L., 2008. Dry deposition study by using dry deposition plate and water surface sampler in Shalu, central Taiwan. Environ. Monit. Assess. 146, 441–451. https://doi.org/10.1007/s10661-007-0090-8. Cindoruk, S.S., Tasdemir, Y., 2014. The investigation of atmospheric deposition distribution of organochlorine pesticides (OCPs) in Turkey. Atmos. Environ. 87, 207–217. https://doi.org/10.1016/j.atmosenv.2014.01.008. Cindoruk, S. Siddik, Tasdemir, Y., 2007. The determination of gas phase dry deposition fluxes and mass transfer coefficients (MTCs) of polychlorinated biphenyls (PCBs) using a modified water surface sampler (WSS). Sci. Total Environ. 381, 212–221. https://doi.org/10.1016/j.scitotenv.2007.03.011. Cindoruk, S. Sıddık, Tasdemir, Y., 2007. Deposition of atmospheric particulate PCBs in suburban site of Turkey. Atmos. Res. 85, 300–309. https://doi.org/10.1016/j. atmosres.2007.02.002. Correa, O., Raun, L., Rifai, H., Suarez, M., Holsen, T., Koenig, L., 2006. Depositional flux of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in an urban setting. Chemosphere 64, 1550–1561. https://doi.org/10.1016/j. chemosphere.2005.11.020. Degrendele, C., Fiedler, H., Kočan, A., Kukučka, P., Přibylová, P., Prokeš, R., Klánová, J., Lammel, G., 2020. Multiyear levels of PCDD/Fs, dl-PCBs and PAHs in background air in central Europe and implications for deposition. Chemosphere 240, 124852. https://doi.org/10.1016/j.chemosphere.2019.124852. Deng, Y., Peng, P., Ren, M., Song, J., Huang, W., 2011. The winter effect on formation of PCDD/Fs in Guangzhou by vehicles: a tunnel study. Atmos. Environ. 45, 2541–2548. https://doi.org/10.1016/j.atmosenv.2011.02.022. Dreyer, A., Minkos, A., 2023. Polychlorinated biphenyls (PCB) and polychlorinated dibenzo-para-dioxins and dibenzofurans (PCDD/F) in ambient air and deposition in the German background. Environ. Pollut. 316, 120511 https://doi.org/10.1016/j. envpol.2022.120511. Eker, G., Tasdemir, Y., 2018. Atmospheric deposition of organochlorine pesticides (OCPs): Species, levels, Diurnal and seasonal fluctuations, transfer velocities. Arch. Environ. Contam. Toxicol. 75, 625–633. https://doi.org/10.1007/s00244-018-05608. Eker Sanli, G., Tasdemir, Y., 2023. Temporal variations of PCBs and their estimated airsoil exchange fluxes measured in seven sites in Bursa-Turkey. Soil Sediment Contam.: Int. J. 32, 843–861. https://doi.org/10.1080/15320383.2022.2143480. Esen, F., Tasdemir, Y., Siddik Cindoruk, S., 2010. Determination of mass transfer rates and deposition levels of polycyclic aromatic hydrocarbons (PAHs) using a modified water surface sampler. Atmos. Pollut. Res. 1, 177–183. https://doi.org/10.5094/ APR.2010.023. Gigliotti, C.L., Brunciak, P.A., Dachs, J., Glenn, T.R., Nelson, E.D., Totten, L.A., Eisenreich, S.J., 2002. Air—water exchange of polycyclic aromatic hydrocarbons in the New York—New Jersey, USA, Harbor Estuary. Environ. Toxicol. Chem. 21, 235–244. https://doi.org/10.1002/etc.5620210203. Gülegen, B., 2024. Investigation of Atmospheric Concentrations and Particulate-Gas Partitioning of Polychlorinated Dibenzo-P-Dioxins and Polychlorinated DibenzoFurans. Bursa Uludag University. Halsall, C.J., Coleman, P.J., Jones, K.C., 1997. Atmospheric deposition of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) and polycyclic aromatic hydrocarbons (PAHs) in two UK cities. Chemosphere 35, 1919–1931. https://doi.org/10.1016/S0045-6535(97)00265-8. Huang, C.-J., Chen, K.-S., Lai, Y.-C., Wang, L.-C., Chang-Chien, G.-P., 2011. Characterization of atmospheric dry deposition of polychlorinated dibenzo-pdioxins/dibenzofuran in a rural area of Taiwan. Aerosol Air Qual. Res. 11, 448–459. https://doi.org/10.4209/aaqr.2011.03.0033. Jähne, B., Haußecker, H., 1998. AIR-WATER gas exchange. Annu. Rev. Fluid Mech. 30, 443–468. https://doi.org/10.1146/annurev.fluid.30.1.443. Khuman, S.N., Chakraborty, P., 2019. Air-water exchange of pesticidal persistent organic pollutants in the lower stretch of the transboundary river Ganga, India. Chemosphere 233, 966–974. https://doi.org/10.1016/j.chemosphere.2019.05.223. Kim, K.-S., Hong, K.-H., Ko, Y.-H., Yoon, K.-D., Kim, M.-G., 2003. Emission characteristics of PCDD/Fs in diesel engine with variable load rate. Chemosphere 53, 601–607. https://doi.org/10.1016/S0045-6535(03)00540-X. Klima, V., Chadyšienė, R., Ivanec-Goranina, R., Jasaitis, D., Vasiliauskienė, V., 2020. Assessment of air pollution with polychlorinated Dibenzodioxins (PCDDs) and polychlorinated Dibenzofuranes (PCDFs) in Lithuania. Atmosphere 11, 759. https:// doi.org/10.3390/atmos11070759. Li, M., Wang, C., Cen, K., Ni, M., Li, X., 2018. Emission characteristics and vapour/ particulate phase distributions of PCDD/F in a hazardous waste incinerator under transient conditions. R. Soc. Open Sci. 5, 171079 https://doi.org/10.1098/ rsos.171079. Fig. 5. Correlation between gas-phase deposition flux and concentration values. Data availability Data will be made available on request. Acknowledgments This study was supported by the Scientific and Technological Research Council of Turkey (TUBITAK) (Grant number 121Y473). The authors thank TUBITAK for the support. We extend our thanks to Dr. Aşkın Birgül for his valuable contributions throughout the study. Our thanks also go to the team at the Ministry of Environment’s Environmental Reference Laboratory for their contributions to the GC-HRMS readings, as well as to the management of BUTAL for opening their doors during the sampling process. Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi. org/10.1016/j.chemosphere.2024.142810. References An Lieshout, L.V., Desmedt, M., Roekens, E., De Fré, R., Van Cleuvenbergen, R., Wevers, M., 2001. Deposition of dioxins in Flanders (Belgium) and a proposition for guide values. Atmos. Environ. 35, 83–90. https://doi.org/10.1016/s1352-2310(01) 00094-2. Asman, Jorgensen, Jensen, et al., 2003. Dry Deposition and Spray Drift of Pesticides to Nearby Water Bodies. Danish Protection Environmental Agency. Birgul, A., 2013. Deposition Mechanisms and Levels of Polyaromatic Hydrocarbons (PAHs) in Bursa Atmosphere. PHD. Thesis (Turkish) 282. Birgül, A., Tasdemir, Y., Cindoruk, S.S., 2011. Atmospheric wet and dry deposition of polycyclic aromatic hydrocarbons (PAHs) determined using a modified sampler. Atmos. Res. 101, 341–353. https://doi.org/10.1016/j.atmosres.2011.03.012. Brubaker, W.W., Hites, R.A., 1997. Polychlorinated dibenzo- p -dioxins and dibenzofurans: gas-phase hydroxyl radical reactions and related atmospheric removal. Environ. Sci. Technol. 31, 1805–1810. https://doi.org/10.1021/ es960950d. Caliskan, B., Celik, S., Tasdemir, Y., 2024. Assessment of single- and dual-PUF-containing passive air samplers for the collection of atmospheric PAHs. Atmos. Pollut. Res. 15, 102009 https://doi.org/10.1016/j.apr.2023.102009. Castro-Jiménez, J., Barhoumi, B., Paluselli, A., Tedetti, M., Jiménez, B., MuñozArnanz, J., Wortham, H., Ridha Driss, M., Sempéré, R., 2017. Occurrence, loading, and exposure of atmospheric particle-bound POPs at the African and European edges of the Western Mediterranean Sea. Environ. Sci. Technol. 51, 13180–13189. https:// doi.org/10.1021/acs.est.7b04614. Castro-Jiménez, J., Eisenreich, S.J., Mariani, G., Skejo, H., Umlauf, G., 2012. Monitoring atmospheric levels and deposition of dioxin-like pollutants in sub-alpine Northern Italy. Atmos. Environ. 56, 194–202. https://doi.org/10.1016/j. atmosenv.2012.03.081. 9 A.A. Noori et al. Chemosphere 363 (2024) 142810 Lin, X., Ying, Y., Wang, X., Ma, Y., Li, M., Huang, Q., Li, X., 2023. Inventory of PCDD/Fs and fly ash characteristics during the e-waste and municipal solid waste Coincineration process. Energy & Fuels 37, 7302–7313. https://doi.org/10.1021/acs. energyfuels.3c00835. McVeety, B.D., Hites, R.A., 1988. Atmospheric deposition of polycyclic aromatic hydrocarbons to water surfaces: a mass balance approach. Atmos. Environ. 22 (1967), 511–536. https://doi.org/10.1016/0004-6981(88)90196-5. Mi, H.-H., Wu, Z.-S., Lin, L.-F., Lai, Y.-C., Lee, Y.-Y., Wang, L.-C., Chang-Chien, G.-P., 2012. Atmospheric dry deposition of polychlorinated dibenzo-p-dioxins/ dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) in Southern Taiwan. Aerosol Air Qual. Res. 12, 1016–1029. https://doi.org/10.4209/aaqr.2012.07.0172. Odabasi, M., Sofuoglu, A., Holsen, T.M., 2001. Mass transfer coefficients for polycyclic aromatic hydrocarbons (PAHs) to the water surface sampler: comparison to modeled results. Atmos. Environ. 35, 1655–1662. https://doi.org/10.1016/S1352-2310(00) 00439-8. Ogura, I., Masunaga, S., Nakanishi, J., 2001a. Atmospheric deposition of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and dioxin-like polychlorinated biphenyls in the Kanto Region, Japan. Chemosphere 44, 1473–1487. https://doi. org/10.1016/S0045-6535(00)00314-3. Ogura, I., Masunaga, S., Nakanishi, J., 2001b. Atmospheric deposition of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and dioxin-like polychlorinated biphenyls in the Kanto region, Japan. Chemosphere 44, 1473–1487. https://doi.org/ 10.1016/S0045-6535(00)00314-3. Oka, H., Kakimoto, H., Miyata, Y., Yonezawa, Y., Niikawa, A., Kyudoh, H., Kizu, R., Hayakawa, K., 2006. Atmospheric deposition of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in Kanazawa, Japan. J. Health Sci. 52, 300–307. https://doi.org/10.1248/jhs.52.300. Pacyna, J.M., 2008. Atmospheric deposition. In: Encyclopedia of Ecology. Elsevier, pp. 275–285. https://doi.org/10.1016/B978-008045405-4.00258-5. Pan, S.Y., Liou, Y.T., Chang, M.B., Chou, C.C.-K., Ngo, T.H., Chi, K.H., 2021. Characteristics of PCDD/Fs in PM2.5 from emission stacks and the nearby ambient air in Taiwan. Sci. Rep. 11, 8093. https://doi.org/10.1038/s41598-021-87468-5. Pryor, S.C., Crippa, P., Sullivan, R.C., 2015. Atmospheric chemistry. In: Reference Module in Earth Systems and Environmental Sciences. Elsevier. https://doi.org/ 10.1016/B978-0-12-409548-9.09177-6. Rasiq, K.T., El-Maradny, A., Orif, M., Bashir, M.E., Turki, A.J., 2019. Polycyclic aromatic hydrocarbons in two polluted lagoons, eastern coast of the Red Sea: levels, probable sources, dry deposition fluxes and air-water exchange. Atmos. Pollut. Res. 10, 880–888. https://doi.org/10.1016/j.apr.2018.12.016. Ren, M., Peng, P., Zhang, S., Yu, L., Zhang, G., Mai, B., Sheng, G., Fu, J., 2007. Atmospheric deposition of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in Guangzhou, China. Atmos. Environ. 41, 592–605. https://doi.org/ 10.1016/j.atmosenv.2006.08.025. Rivero, J.R., Panagakos, G., Lieber, A., Hornbostel, K., 2020. Hollow fiber membrane contactors for post-combustion carbon capture: a review of modeling approaches. Membranes 10, 382. https://doi.org/10.3390/membranes10120382. Sakata, M., Asakura, K., 2011. Atmospheric dry deposition of trace elements at a site on Asian-continent side of Japan. Atmos. Environ. 45, 1075–1083. https://doi.org/ 10.1016/j.atmosenv.2010.11.043. Sakata, M., Tani, Y., Takagi, T., 2008. Wet and dry deposition fluxes of trace elements in Tokyo Bay. Atmos. Environ. 42, 5913–5922. https://doi.org/10.1016/j. atmosenv.2008.03.027. Sakin, A.E., Tasdemir, Y., 2020. Determination of fluxes and mass transfer coefficients of polychlorinated biphenyls (PCBs). Atmos. Pollut. Res. 11, 1379–1385. https://doi. org/10.1016/j.apr.2020.05.006. Schröder, J., Welsch-Pausch, K., McLachlan, M.S., 1997. Measurement of atmospheric deposition of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) to a soil. Atmos. Environ. 31, 2983–2989. https://doi.org/10.1016/S1352-2310(97) 00107-6. Schuhmacher, M., Jones, K.C., Domingo, J.L., 2006. Air-vegetation transfer of PCDD/ PCDFs: an assessment of field data and implications for modeling. Environ. Pollut. 142, 143–150. https://doi.org/10.1016/j.envpol.2005.09.017. Seyfioglu, R., Odabasi, M., 2006. Investigation of air-water exchange of formaldehyde using the water surface sampler: flux enhancement due to chemical reaction. Atmos. Environ. 40, 3503–3512. https://doi.org/10.1016/j.atmosenv.2006.01.048. Shahin, U.M., Holsen, T.M., Odabasi, M., 2002. Dry deposition measured with a water surface sampler: a comparison to modeled results. Atmos. Environ. 36, 3267–3276. https://doi.org/10.1016/S1352-2310(02)00315-1. Shih, M., Lee, W.S., Chang-Chien, G.P., Wang, L.C., Hung, C.Y., Lin, K.C., 2006. Dry deposition of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in ambient air. Chemosphere 62, 411–416. https://doi.org/10.1016/j. chemosphere.2005.04.064. Silsby, J.A., Simon, S., Walsh, J.L., Hasan, M.I., 2021. The influence of gas–liquid interfacial transport theory on numerical modelling of plasma activation of water. Plasma Chem. Plasma Process. 41, 1363–1380. https://doi.org/10.1007/s11090021-10182-7. Singh, S.B., Kulshrestha, G., 1997. Gas chromatographic analysis of polychlorinated dibenzo-p-dioxins and dibenzofurans. J. Chromatogr. A 774, 97–109. https://doi. org/10.1016/S0021-9673(97)00336-1. Sobotka, J., Smedes, F., Vrana, B., 2022. Performance comparison of silicone and lowdensity polyethylene as passive samplers in a global monitoring network for aquatic organic contaminants. Environ. Pollut. 302, 119050 https://doi.org/10.1016/j. envpol.2022.119050. Song, S., Chen, K., Huang, T., Ma, J., Wang, J., Mao, X., Gao, H., Zhao, Y., Zhou, Z., 2023. New emission inventory reveals termination of global dioxin declining trend. J. Hazard Mater. 443, 130357 https://doi.org/10.1016/j.jhazmat.2022.130357. Suryani, R.C., Lee, W.-J., Mutiara, M.P.E., Mwangi, J.K., Wang, L.-C., Lin, N.-H., ChangChien, G.-P., 2015. Atmospheric deposition of polychlorinated dibenzo-p-dioxins and dibenzofurans at coastal and high mountain areas in taiwan. Aerosol Air Qual. Res. 15, 1390–1411. https://doi.org/10.4209/aaqr.2015.04.0246. Tasdemir, Y., Esen, F., 2008. Deposition of polycyclic aromatic hydrocarbons (PAHs) and their mass transfer coefficients determined at a trafficked site. Arch. Environ. Contam. Toxicol. https://doi.org/10.1007/s00244-007-9096-z. Tasdemir, Y., Esen, F., 2007. Dry deposition fluxes and deposition velocities of PAHs at an urban site in Turkey. Atmos. Environ. 41, 1288–1301. https://doi.org/10.1016/j. atmosenv.2006.09.037. Tasdemir, Y., Holsen, T.M., 2006. Gas-phase deposition of polychlorinated biphenyls (PCBs) to a water surface sampler. Journal of Environmental Science and Health Part A Toxic/Hazardous Substances and Environmental Engineering 41, 2071–2087. https://doi.org/10.1080/10934520600867797. Tasdemir, Y., Odabasi, M., Holsen, T.M., 2007. PCB mass transfer coefficients determined by application of a water surface sampler. Chemosphere 66, 1554–1560. https://doi. org/10.1016/j.chemosphere.2006.08.009. Tasdemir, Y., Odabasi, M., Holsen, T.M., 2005. Measurement of the vapor phase deposition of polychlorinated bipheyls (PCBs) using a water surface sampler. Atmos. Environ. 39, 885–897. https://doi.org/10.1016/j.atmosenv.2004.10.032. Themba, N., Sibali, L.L., Chokwe, T.B., 2023. A review on the formation and remediations of polychlorinated dibenzo p-dioxins and dibenzo-furans (PCDD/Fs) during thermal processes with a focus on MSW process. Air Quality, Atmosphere & Health 16, 2115–2132. https://doi.org/10.1007/s11869-023-01394-1. Totten, L.A., Gigliotti, C.L., VanRy, D.A., Offenberg, J.H., Nelson, E.D., Dachs, J., Reinfelder, J.R., Eisenreich, S.J., 2004. Atmospheric concentrations and deposition of polychorinated biphenyls to the hudson river estuary. Environ. Sci. Technol. 38, 2568–2573. https://doi.org/10.1021/es034878c. Vardar, N., Odabasi, M., Holsen, T.M., 2002. Particulate dry deposition and overall deposition velocities of polycyclic aromatic hydrocarbons. J. Environ. Eng. 128, 269–274. https://doi.org/10.1061/(ASCE)0733-9372(2002)128:3(269. Wang, C., Xu, Z., Lai, C., Sun, X., 2018. Beyond the standard two-film theory: computational fluid dynamics simulations for carbon dioxide capture in a wetted wall column. Chem. Eng. Sci. 184, 103–110. https://doi.org/10.1016/j. ces.2018.03.021. Wang, W.-C., Lin, W.-H., Kuo, C.-P., Wu, J.-Y., 2012. The relation between dioxin concentration from exhaust gas of diesel engine and chlorine content. J. Anal. Appl. Pyrol. 94, 10–16. https://doi.org/10.1016/j.jaap.2011.12.010. Wang, Y.-F., Hou, H.-C., Li, H.-W., Lin, L.-F., Wang, L.-C., Chang-Chien, G.-P., You, Y.-S., 2010. Dry and wet depositions of polychlorinated dibenzo-p-dioxins and dibenzofurans in the atmosphere in Taiwan. Aerosol Air Qual. Res. 10, 378–390. https://doi.org/10.4209/aaqr.2010.04.0024. Wei, X., Xie, F., Dong, C., Wang, P., Xu, J., Yan, F., Zhang, Z., 2022. Safe disposal of hazardous waste incineration fly ash: stabilization/solidification of heavy metals and removal of soluble salts. J. Environ. Manag. 324, 116246 https://doi.org/10.1016/j. jenvman.2022.116246. Wu, Y., Lin, L., Hsieh, L., Wang, L., Chang-chien, G., 2009. Atmospheric Dry Deposition of Polychlorinated Dibenzo- P -dioxins and Dibenzofurans in the Vicinity of Municipal Solid Waste Incinerators, vol. 162, pp. 521–529. https://doi.org/ 10.1016/j.jhazmat.2008.05.075. Yu, F., Cui, K., Sheu, H.-L., Hsieh, Y.-K., Tian, X., 2021. Atmospheric concentration, particle-bound content, and dry deposition of PCDD/Fs. Aerosol Air Qual. Res. 21, 210059 https://doi.org/10.4209/aaqr.210059. Zhang, M., Buekens, A., Li, X., 2017. Open burning as a source of dioxins. Crit. Rev. Environ. Sci. Technol. 47, 543–620. https://doi.org/10.1080/ 10643389.2017.1320154. Zhou, S., Guan, Z., Chen, D., Hong, L., 2024. New approach for the inhibition of PCDD/Fs formation in fly ash by carbohydrazide during refuse-derived fuel (RDF) combustion. Chin. J. Anal. Chem. 100357 https://doi.org/10.1016/j.cjac.2024.100357. Zhu, J., Tang, H., Xing, J., Lee, W.-J., Yan, P., Cui, K., 2017. Atmospheric deposition of polychlorinated dibenzo-p-dioxins and dibenzofurans in two cities of Southern China. Aerosol Air Qual. Res. 17, 1798–1810. https://doi.org/10.4209/ aaqr.2017.05.0177. 10