Octanol-air Partition Coefficient Research Articles

Influence of Temperature, Relative Humidity, and Soil Properties on the Soil-Air Partitioning of Semivolatile Pesticides: Laboratory Measurements and Predictive Models.

Soil-air partition coefficient (Ksoil-air) values are often employed to investigate the fate of organic contaminants in soils; however, these values have not been measured for many compounds of interest, including semivolatile current-use pesticides. Moreover, predictive equations for estimating Ksoil-air values for pesticides (other than the organochlorine pesticides) have not been robustly developed, due to a lack of measured data. In this work, a solid-phase fugacity meter was used to measure the Ksoil-air values of 22 semivolatile current- and historic-use pesticides and their degradation products. Ksoil-air values were determined for two soils (semiarid and volcanic) under a range of environmentally relevant temperature (10-30 °C) and relative humidity (30-100%) conditions, such that 943 Ksoil-air measurements were made. Measured values were used to derive a predictive equation for pesticide Ksoil-air values based on temperature, relative humidity, soil organic carbon content, and pesticide-specific octanol-air partition coefficients. Pesticide volatilization losses from soil, calculated with the newly derived Ksoil-air predictive equation and a previously described pesticide volatilization model, were compared to previous results and showed that the choice of Ksoil-air predictive equation mainly affected the more-volatile pesticides and that the way in which relative humidity was accounted for was the most critical difference.

Seasonal variations in atmospheric concentrations and gas–particle partitioning of PCDD/Fs and dioxin-like PCBs around industrial sites in Shanghai, China

Gas and particle phase air samples were collected in summer and winter around industrial sites in Shanghai, China, to allow the concentrations, profiles, and gas–particle partitioning of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) to be determined. The total 2,3,7,8-substituted PCDD/F and dl-PCB toxic equivalent (TEQ) concentrations were 14.2–182 fg TEQ/m3 (mean 56.8 fg TEQ/m3) in summer and 21.9–479 fg TEQ/m3 (mean 145 fg TEQ/m3) in winter. The PCDD/Fs tended to be predominantly in the particulate phase, while the dl-PCBs were predominantly found in the gas phase, and the proportions of all of the PCDD/F and dl-PCB congeners in the particle phase increased as the temperature decreased. The logarithms of the gas–particle partition coefficients correlated well with the subcooled liquid vapor pressures of the PCDD/Fs and dl-PCBs for most of the samples. Gas–particle partitioning of the PCDD/Fs deviated from equilibrium either in summer or winter close to local sources, and the Junge–Pankow model and predictions made using a model based on the octanol–air partition coefficient fitted the measured particulate PCDD/F fractions well, indicating that absorption and adsorption mechanism both contributed to the partitioning process. However, gas–particle equilibrium of the dl-PCBs was reached more easily in winter than in summer. The Junge–Pankow model predictions fitted the dl-PCB data better than did the predictions made using the model based on the octanol–air partition coefficient, indicating that adsorption mechanism made dominated contribution to the partitioning process.

Fate and Transport of Phthalates in Indoor Environments and the Influence of Temperature: A Case Study in a Test House.

A case study in a test house was conducted to investigate the fate and transport of benzyl butyl phthalate (BBzP) and di-2-ethylhexyl phthalate (DEHP) in residential indoor environments and the influence of temperature. Total airborne concentrations of phthalates were sensitive to indoor temperatures, and their steady-state concentration levels increased by a factor of 3 with an increase in temperature from 21 to 30 °C. Strong sorption of phthalates was observed on interior surfaces, including dust, dish plates, windows, mirrors, fabric cloth, and wood. Equilibrium partitioning coefficients for phthalates adsorbed to these surfaces were determined, and their values decreased with increasing temperature. For impervious surfaces, dimensionless partitioning coefficients were calculated and found to be comparable to reported values of the octanol-air partition coefficients of phthalates, Koa, suggesting that an organic film may develop on these surfaces. In addition, sorption kinetics was studied experimentally, and the equilibration time scale for impervious surfaces was found to be faster than that of fabric cloth. Finally, using an indoor fate model to interpret the measurement results, there was good agreement between model predictions and the observed indoor air concentrations of BBzP in the test house.

Measurements of octanol–air partition coefficients, vapor pressures and vaporization enthalpies of the (E) and (Z) isomers of the 2-ethylhexyl 4-methoxycinnamate as parameters of environmental impact assessment

2-Ethylhexyl 4-methoxycinnamate is one of the UVB blocking agents more widely used in a variety of industrial fields. There are more than one hundred industrial suppliers worldwide. Given the enormous annual consumption of octinoxate, problems that arise due to the accumulation of this compound in nature should be taken into consideration. The GC-RT was used in this work with the aim of determining the vapor pressure, enthalpies of vaporization and octanol–air partition coefficient, for the BBP, DOP, E- and Z-EHMC esters. The results showed that Z-EHMC is almost five times more volatile than E-EHMC. Moreover, BBP, Z-EHMC and E-EHMC can be classified as substances with a relatively low mobility since they lie within the range of 8<logKOA<10 and −4<log(PL/Pa)<−2, while DOP lies in the range of logKOA>10 and log(PL/Pa)<−4, therefore, a low mobility can be expected. From these parameters, their particle-bound fraction and gas–particle partition coefficient were also derived.

Influential role of black carbon in the soil–air partitioning of polychlorinated biphenyls (PCBs) in the Indus River Basin, Pakistan

Levels of polychlorinated biphenyls (PCBs) were assessed in surface soils and passive air samples from the Indus River Basin, and the influential role of black carbon (BC) in the soil–air partitioning process was examined. ∑26–PCBs ranged between 0.002–3.03pgm−3 and 0.26–1.89ngg−1 for passive air and soil samples, respectively. Lower chlorinated (tri- and tetra-) PCBs were abundant in both air (83.9%) and soil (92.1%) samples. Soil–air partitioning of PCBs was investigated through octanol–air partition coefficients (KOA) and black carbon–air partition coefficients (KBC–A). The results of the paired-t test revealed that both models showed statistically significant agreement between measured and predicted model values for the PCB congeners. Ratios of fBCKBC–AδOCT/fOMKOA>5 explicitly suggested the influential role of black carbon in the retention and soil–air partitioning of PCBs. Lower chlorinated PCBs were strongly adsorbed and retained by black carbon during soil–air partitioning because of their dominance at the sampling sites and planarity effect.

Variations of Flame Retardant, Polycyclic Aromatic Hydrocarbon, and Pesticide Concentrations in Chicago's Atmosphere Measured using Passive Sampling.

Atmospheric concentrations of flame retardants, polycyclic aromatic hydrocarbons, and pesticides were measured using passive air samplers equipped with polyurethane foam disks to find spatial information in and around Chicago, Illinois. Samplers were deployed around the greater Chicago area for intervals of 6 weeks from 2012 to 2013 (inclusive). Volumes were calculated using passive sampling theory and were based on meteorology and the compounds' octanol-air partition coefficients. Geometric mean concentrations of total polybrominated diphenyl ethers ranged from 11 to 150 pg/m3, and tributyl phosphate, tris(2-chloroethyl)phosphate, tris(1-chloro-2-propyl)phosphate, and triphenyl phosphate concentrations were in the ranges of 54-290, 32-340, 130-580, and 170-580 pg/m3, respectively. The summed concentrations of 16 PAHs ranged from 8700 to 52,000 pg/m3 over the sampling area, and DDT, chlordane, and endosulfan concentrations were in the ranges of 2.7-9.9, 8.2-66, and 16-85 pg/m3, respectively. Sampling sites were split into two groups depending on their distances from the Illinois Institute of Technology campus in Chicago. With a few exceptions, the concentrations of most compound groups in the city's center were the same or slightly higher than those measured >45 km away. The data also showed that the concentrations measured with a passive atmospheric sampling system are in good agreement with those measured with an active, high-volume, sampling system. Given that the sampling times are different (passive, 43 days; active, 1 day), and that both of these measured concentrations cover about 5 orders of magnitude, the agreement between these passive and active sampling methods is excellent.

Externally predictive single-descriptor based QSPRs for physico-chemical properties of polychlorinated-naphthalenes: Exploring relationships of log SW, log KOA, and log KOW with electron-correlation

Quantitative structure–property relationships (QSPRs), based only on a single-parameter, are proposed for the prediction of physico-chemical properties, namely, aqueous solubility (logSW), octanol–water partition coefficient (logKOW) and octanol–air partition coefficient (logKOA) of polychloronaphthalenes (PCNs) including all the 75 chloronaphthalene congeners. The QSPR models are developed using molecular descriptors computed through quantum mechanical methods including ab-initio as well as advanced semi-empirical methods. The predictivity of the developed models is tested through state-of-the-art external validation procedures employing an external prediction set of compounds. To analyse the role of instantaneous interactions between electrons (the electron-correlation), the models are also compared with those developed using only the electron-correlation contribution of the quantum chemical descriptor. The electron-correlation contribution towards the chemical hardness and the LUMO energy are observed to be the best predictors for octanol–water partition coefficient, whereas for the octanol–air partition coefficient, the total electronic energy and electron-correlation energy are found to be reliable descriptors, in fact, even better than the polarisability. For aqueous solubility of PCNs, the absolute electronegativity is observed to be the best predictor. This work suggests that the electron-correlation contribution of a quantum-chemical descriptor can be used as a reliable indicator for physico-chemical properties, particularly the partition coefficients.

Temperature dependence of Henry's law constants and KOA for simple and heteroatom-substituted PAHs by COSMO-RS

Henry's Law constants (H) and octanol–air partition coefficients (KOA) for polycyclic aromatic hydrocarbons (PAHs) and selected nitrogen-, oxygen- and sulfur-containing derivatives have been computed using the COSMO-RS method between −5 and 40 °C in 5 °C intervals. The accuracy of the estimation was assessed by comparison of COSMOtherm values with published experimental temperature-dependence data for these and similar PAHs. COSMOtherm log H estimates with temperature-variation for parent PAHs are shown to have a root-mean-square (RMS) error of 0.38 (PAH), based on available validation data. Estimates of O-, N- and S-substituted derivative log H values are found to have RMS errors of 0.30 at 25 °C. Log KOA estimates with temperature variation from COSMOtherm are shown to be strongly correlated with experimental values for a small set of unsubstituted PAHs, but with a systematic underestimation and associated RMS error of 1.11. Similar RMS error of 1.64 was found for COSMO-RS estimates of a group of critically-evaluated log KOA values at room temperature. Validation demonstrates that COSMOtherm estimates of H and KOA are of sufficient accuracy to be used for property screening and preliminary environmental risk assessment, and perform very well for modeling the influence of temperature on partitioning behavior in the temperature range −5 to 40 °C. Temperature-dependent shifts of up to 2 log units in log H and one log unit for log KOA are predicted for PAH species over the range −5 and 40 °C. Within the family of PAH molecules, COSMO-RS is sufficiently accurate to make it useful as a source of estimates for modeling purposes, following corrections for systematic underestimation of KOA. Average changes in the values for log H and log KOA upon substitution are given for various PAH substituent categories, with the most significant shifts being associated with the ionizing nitro functionality and keto groups.

Assessing the combined influence of TOC and black carbon in soil–air partitioning of PBDEs and DPs from the Indus River Basin, Pakistan

Levels of polybrominated diphenyl ethers (PBDEs) and dechlorane plus (DPs) were investigated in the Indus River Basin from Pakistan. Concentrations of ∑PBDEs and ∑DPs were ranged between 0.05 and 2.38 and 0.002–0.53 ng g−1 in the surface soils while 1.43–22.1 and 0.19–7.59 pg m−3 in the passive air samples, respectively. Black carbon (fBC) and total organic carbon (fTOC) fractions were also measured and ranged between 0.73 and 1.75 and 0.04–0.2%, respectively. The statistical analysis revealed strong influence of fBC than fTOC on the distribution of PBDEs and DPs in the Indus River Basin soils. BDE's congener profile suggested the input of penta–bromodiphenylether (DE-71) commercial formulation in the study area. Soil–air partitioning of PBDEs were investigated by employing octanol-air partition coefficients (KOA) and black carbon-air partition coefficients (KBC−A). The results of both models suggested the combined influence of total organic carbon (absorption) and black carbon (adsorption) in the studied area.

Prediction of gas/particle partitioning of polybrominated diphenyl ethers (PBDEs) in global air: A theoretical study

Abstract. Gas/particle (G/P) partitioning of semi-volatile organic compounds (SVOCs) is an important process that primarily governs their atmospheric fate, long-range atmospheric transport, and their routes of entering the human body. All previous studies on this issue are hypothetically based on equilibrium conditions, the results of which do not predict results from monitoring studies well in most cases. In this study, a steady-state model instead of an equilibrium-state model for the investigation of the G/P partitioning behavior of polybrominated diphenyl ethers (PBDEs) was established, and an equation for calculating the partition coefficients under steady state (KPS) of PBDEs (log KPS = log KPE + logα) was developed in which an equilibrium term (log KPE = log KOA + logfOM −11.91 where fOM is organic matter content of the particles) and a non-equilibrium term (log α, caused by dry and wet depositions of particles), both being functions of log KOA (octanol–air partition coefficient), are included. It was found that the equilibrium is a special case of steady state when the non-equilibrium term equals zero. A criterion to classify the equilibrium and non-equilibrium status of PBDEs was also established using two threshold values of log KOA, log KOA1, and log KOA2, which divide the range of log KOA into three domains: equilibrium, non-equilibrium, and maximum partition domain. Accordingly, two threshold values of temperature t, tTH1 when log KOA = log KOA1 and tTH2 when log KOA = log KOA2, were identified, which divide the range of temperature also into the same three domains for each PBDE congener. We predicted the existence of the maximum partition domain (the values of log KPS reach a maximum constant of −1.53) that every PBDE congener can reach when log KOA ≥ log KOA2, or t ≤ tTH2. The novel equation developed in this study was applied to predict the G/P partition coefficients of PBDEs for our Chinese persistent organic pollutants (POPs) Soil and Air Monitoring Program, Phase 2 (China-SAMP-II) program and other monitoring programs worldwide, including in Asia, Europe, North America, and the Arctic, and the results matched well with all the monitoring data, except those obtained at e-waste sites due to the unpredictable PBDE emissions at these sites. This study provided evidence that the newly developed steady-state-based equation is superior to the equilibrium-state-based equation that has been used in describing the G/P partitioning behavior over decades. We suggest that the investigation on G/P partitioning behavior for PBDEs should be based onsteady-state, not equilibrium state, and equilibrium is just a special case of steady-state when non-equilibrium factors can be ignored. We also believe that our new equation provides a useful tool for environmental scientists in both monitoring and modeling research on G/P partitioning of PBDEs and can be extended to predict G/P partitioning behavior for other SVOCs as well.

Sorption behaviour of targeted volatile organic compounds on airborne particulate matter using selected ion flow tube mass spectrometry

Intensive agriculture emits air pollutants such as inorganic gases, volatile organic compounds (VOC) and airborne particulate matter. The public can suffer from severe odour nuisance caused by these emissions, particularly in areas with high population densities. Odorous compounds are not only present in the free gas phase but undergo a partitioning between the gas phase and particulate matter making particles possible odour carriers. In order to investigate this partitioning behaviour, an advanced analytical method was developed using selected ion flow tube mass spectrometry (SIFT-MS). This method was used to determine the particle-to-air partitioning coefficients of 4 important organic odorants (acetic acid, butanoic acid, phenol and dimethyl disulphide). An air stream with constant VOC concentration was generated in a home-made system and was injected as a step function onto a chromatographic column packed with particles (PM 10 ) collected from a pig stable using high volume sampling. From the registered breakthrough curves, dimensionless particle-to-air partitioning coefficients were calculated. They ranged from 13 × 10 3 ± 3.1 × 10 3 for dimethyl disulphide to 16 × 10 5 ± 1.7 × 10 5 for phenol. Partitioning coefficients can be estimated using octanol–air partitioning coefficients available from the literature (r 2 = 0.94). The results show that particles were enriched in VOC but the fraction of sorbed volatiles was low ( 10 concentration of 1 mg m −3 .

Persistent Organic Pollutants (POPs) on Fine and Coarse Atmospheric Particles Measured at Two (Urban and Industrial) Sites

Particle size is an important parameter in terms of human health effects, fate and transport of pollutants associated with particulate matter (PM). Persistent organic pollutant (POP) (i.e., PAHs, PCBs, PBDEs, and OCPs) concentrations were measured on fine (dp < 2.5 µm) and coarse (2.5 µm < dp < 10 µm) aerosol samples collected at two (Urban and Industrial) sites in Izmir, Turkey. POP concentrations were ~2 times higher at the Industrial site due to the local sources (i.e., scrap processing iron-steel plants, ship-breaking activities, a petroleum refinery, and a petrochemical plant) that were recently shown to be hot spots emitting these pollutants. The size distribution of particle-phase POPs indicated that they were mostly (> 50%) associated with fine PM. The larger contribution of all POP compounds to fine PM could be attributed to the higher sorption capacity of fine PM because of its relatively higher organic matter content compared to coarse PM. Fine PM fraction of POPs significantly increased with octanol-air partition coefficient (KOA) (p < 0.01) since larger KOA values favor the partitioning of POPs to PM. Relationships between fine PM percent and meteorological parameters (i.e., temperature and wind speed) were also investigated. Fine PM percent decreased with temperature and the correlations were significant for 51% of the compounds (p < 0.01), suggesting that the decrease in KOA with increasing temperature results in less partitioning to PM. Fine PM fraction also decreased with wind speed (p < 0.01 for the 52% of the compounds) that could be attributed to increased resuspension of contaminated coarse particles with increasing wind speed. Using the experimental deposition velocities reported for several POPs in the study area it was shown that dry particle deposition velocity significantly decreases with increasing fine PM fraction (p < 0.01). This indicates that the increase in fine fraction of POPs with decreasing volatility may have important implications for their environmental fate and transport.

Seasonal Variation and Gas/Particle Partitioning of PCBs in Air from Central Urban Area of an Industrial Base and Coastal City -Tianjin, China

ABSTRACTThe 26 air samples were collected from Tianjin urban areas from July 2010 to May 2011 for the analysis of 86 PCB congeners to investigate the gas/particle partitioning of PCBs. The total PCBs concentration (in pg/m3) ranged from 31.28 to 650.33 (mean: 273.77) and showed a significantly seasonal variation as summer > autumn > spring > winter. Gas PCBs accounted for 80.79% of total PCBs. The fraction of each gas PCB homolog increased with the decreasing chlorine atoms. The contribution of gas PCBs to total PCBs showed a strong seasonal variation with summer (94.07%) > autumn (78.91%) > spring (78.19%) > winter (56.02%). Tri-, tetra- and penta-PCBs were the predominantly homologs in Tianjin atmosphere. The natural logarithm of partial pressure of PCBs were well correlated with the inverse absolute environmental temperature (R = 0.79). The steep slope of –4933.64 obtained from Clausius–Clapeyron (C.C) plot indicated the influence of local PCBs sources. In generally, the C.C slopes and the surface-air exchange enthalpy (∆HSA) for different PCB homologs increased with the increasing chlorine atoms. The fraction of particle bound PCBs were underestimated for PCBs with PL0 > 10–3.85 Pa and overestimated for PCB congeners with PL0 < 10–3.85 Pa by Junge-Pankow model. The logarithm of particle/gas partitioning coefficients (log KP) of PCBs were well correlated with the logarithm of respective sub-cooled vapor pressures (log PL0) (R = 0.72) and the octanol-air partition coefficient (log KOA) (R = 0.77). The slopes for log KP against log PL0 and log KOA plots were –0.44 and 0.48, deviated significantly from the expected –1 and +1 for the equilibrium state of gas/particle partitioning, possibly explained by the emission of PCBs and particles from the local industries and other sources. The TEQ concentrations (fg/m3) for 12 dioxin-like PCB congeners ranged from 35.628 to 612.796 with the mean value as 144.878.

Plant leaves as indoor air passive samplers for volatile organic compounds (VOCs)

Volatile organic compounds (VOCs) enter indoor environments through internal and external sources. Indoor air concentrations of VOCs vary greatly but are generally higher than outdoors. Plants have been promoted as indoor air purifiers for decades, but reports of their effectiveness differ. However, while air-purifying applications may be questionable, the waxy cuticle coating on leaves may provide a simple, cost-effective approach to sampling indoor air for VOCs. To investigate the potential use of plants as indoor air VOC samplers, a static headspace approach was used to examine the relationship between leaf and air concentrations, leaf lipid contents and octanol-air partition coefficients (Koa) for six VOCs and four plant species. The relationship between leaf and air concentrations was further examined in an actual residence after the introduction of several chlorinated VOC emission sources. Leaf-air concentration factors (LACFs), calculated from linear regressions of the laboratory headspace data, were found to increase as the solvent extractable leaf lipid content and Koa value of the VOC increased. In the studies conducted in the residence, leaf concentrations paralleled the changing air concentrations, indicating a relatively rapid air to leaf VOC exchange. Overall, the data from the laboratory and residential studies illustrate the potential for plant leaves to be used as cost effective, real-time indoor air VOC samplers.

Soil-air partitioning of polychlorinated biphenyls and total dichloro-diphenyl-trichloroethanes

Soil-air partitioning is an important diffusive process that affects the environmental fate of organic compounds and human health. In this review, factors affecting the soil-air partitioning of polychlorinated biphenyls (PCBs) and total dichloro-diphenyl-trichloroethanes (p,p'- and o,p'- isomers of DDT, DDD, and DDE) are discussed. Hydrophobicity is an important factor that influences soil-air partition coefficients (KSA), and its effect can be explained through enthalpy of phase change for soil-air partitioning transfer (ΔHSA). For more hydrophobic compounds, a sharp increase in the KSA of PCBs and organochlorines can be seen in the early aging period. During the aging period, the temperature has a significant effect on the more hydrophobic organic compounds. The content and properties of soil or- ganic matter influence the KSA of the target compounds. Generally, KSA decreases with increasing rela- tive humidity in soils. The linear trend between KSA and temperature (T) changes at 0 °C. Freezing the air or soil in experiments would change the research results. On the basis of factors influencing soil-air partitioning, a multipleparameter (T, organic carbon fraction (fOC), and octanol-air partition coefficient (KOA)) model is put forward to predict the KSA values for PCBs and total DDTs.

Trophodynamics of current use pesticides and ecological relationships in the Bathurst region vegetation-caribou-wolf food chain of the Canadian Arctic.

The bioaccumulation of current use pesticides (CUPs) and stable isotopes of carbon and nitrogen were investigated in vegetation-caribou-wolf food chain in the Bathurst region (Nunavut, Canada). Volumetric bioconcentration factors (BCF(v)) in vegetation were generally greatest for dacthal (10-12) ≥ endosulfan sulfate (10-11) > ß-endosulfan (>9.0-9.7) ≥ pentachloronitrobenzene (PCNB; 8.4-9.6) > α-endosulfan (8.3-9.3) > chlorpyrifos (8.0-8.7) >chlorothalonil (7.6-8.3). The BCF(v) values in vegetation were significantly correlated with the logarithm of the octanol-air partition coefficients (log K(OA)) of CUPs (r(2) = 0.90, p = 0.0040), although dacthal was an outlier and not included in this relationship. Most biomagnification factors (BMFs) for CUPs in caribou:diet comparisons were significantly less than 1. Similarly, the majority of wolf:caribou BMFs were either significantly less than 1 or were not statistically greater than 1. Significant trophic magnification factors (TMFs) were all less than 1, indicating that these CUPs exhibit trophic dilution through this terrestrial food chain. The log K(OA) reasonably predicted bioconcentration in vegetation for most CUPs but was not correlated with BMFs or TMFs in mammals. Our results, along with those of metabolic studies, suggest that mammals actively metabolize these CUPs, limiting their biomagnification potential despite entry into the food chain through effective bioconcentration in vegetation.

Occurrence and carcinogenic potential of airborne polycyclic aromatic hydrocarbons in some large-scale enclosed/semi-enclosed vehicle parking areas

Polycyclic aromatic hydrocarbons (PAHs) originating from vehicle exhaust have aroused much attention due to their potential healthy effect. In this study, air samples were collected from three representative parking lots in a metropolitan area, analyzed for PAHs and evaluated for inhalation risk. Atmospheric PAH levels of these parking areas ranged between 1178–4793ngm−3, one order of magnitude higher than general urban areas. Their benzo[a]pyrene equivalent (BaPeq) values varied in 11.0–98.0ngm−3, far exceeding the air quality standard of WHO (1.0ngm−3). Monte Carlo simulation (100,000 trials) results suggest that the potential lifetime inhalation cancer risks of PAHs were 0.27×10−5 to 7.11×10−5 for park employees, which are in the acceptable range acknowledged by US EPA (1.0×10−6 to 1.0×10−4). Several source diagnostic methods proved that vehicle exhaust was the dominant PAH contributor of these parks with the contribution percentages being >53%; oil combustion and/or coal combustion were other important sources. Logarithms of gas-particle distribution coefficients (Kps) of PAHs in all studied parks were linearly correlated with those of both their sub-cooled vapor pressures (pLs) and octanol–air partition coefficients (KOAs). The correlation coefficients indicated that both adsorption onto black carbon and absorption into organic matter were involved in the partition process, but the latter was dominant.

Concentrations, atmospheric partitioning, and air–water/soil surface exchange of polychlorinated dibenzo-p-dioxin and dibenzofuran along the upper reaches of the Haihe River basin, North China

Polychlorinated dibenzo-p-dioxin and dibenzofuran (PCDD/PCDF) were overall measured and compared in ambient air, water, soils, and sediments along the upper reaches of the Haihe River of North China, so as to evaluate their concentrations, profiles, and to understand the processes of gas-particle partitioning and air-water/soil exchange. The following results were obtained: (1) The average concentrations (toxic equivalents, TEQs) of 2,3,7,8-PCDD/PCDF in air, water, sediment, and soil samples were 4,855 fg/m(3), 9.5 pg/L, 99.2 pg/g dry weight (dw), and 56.4 pg/g (203 fg TEQ/m(3), 0.46 pg TEQ/L, 2.2 pg TEQ/g dw, and 1.3 pg TEQ/g, respectively), respectively. (2) Although OCDF, 1,2,3,4,6,7,8-HpCDF, OCDD, and 1,2,3,4,6,7,8-HpCDD were the dominant congeners among four environmental sinks, obvious discrepancies of these congener and homologue patterns of PCDD/PCDF were observed still. (3) Significant linear correlations for PCDD/PCDF were observed between the gas-particle partition coefficient (K p) and the subcooled liquid vapor pressure (P L (0)) and octanol-air partition coefficient (K oa). (4) Fugacity fraction values of air-water exchange indicated that most of PCDD/PCDF homologues were dominated by net volatilization from water into air. The low-chlorinated PCDD/PCDF (tetra- to hexa-) presented a strong net volatilization from the soil into air, while high-chlorinated PCDD/PCDF (hepta- to octa-) were mainly close to equilibrium for air-soil exchange.

Occurrence and gas/particle partitioning of short- and medium-chain chlorinated paraffins in the atmosphere of Fildes Peninsula of Antarctica

Chlorinated paraffins (CPs) were measured in air samples at a remote air monitoring site established in Georgia King Island, Fildes Peninsula of Antarctica (Great Wall Station, China) to study the long-range atmospheric transport of these anthropogenic pollutants to the Antarctic. Gas- and particle-phase CPs were collected using polyurethane foam plugs (PUF) and glass fiber filters (GFF) respectively during summertime of 2012. The total atmospheric levels of SCCPs and MCCPs ranged from 9.6 to 20.8 pg m−3 (average: 14.9 pg m−3) and 3.7–5.2 pg m−3 (average: 4.5 pg m−3), respectively. C10 and C11 carbon chain homologues with Cl5 and Cl6 chlorine atoms predominated in SCCP formula groups both in gas- and particle-phase. Significant linear correlation was found between gas/particle partition coefficients (KP) and sub-cooled liquid vapor pressures (pL°) (R2 = 0.437, p < 0.01), as well as KP and octanol–air partition coefficients (KOA) (R2 = 0.442, p < 0.01). Absolute slope values of two regression models (0.31 and 0.39) were less than 0.6 indicating that the way of absorption into organic matter of aerosol played a more important role on atmospheric partitioning and transferring of CPs in remote Antarctic area. Both the Junge–Pankow model and the KOA-based model tended to underestimate the sorption of lower chlorinated CPs and overestimate the sorption of highly chlorinated CPs.

Indoor phthalate concentration and exposure in residential and office buildings in Xi'an, China

Indoor phthalate levels were investigated in 28 buildings, including 14 office and 14 residential buildings in Xi'an, China. Phthalate esters in the gas-, particle-, and dust- phase were measured separately. Four phthalates including dimethyl phthalate (DMP), diisobutyl phthalate (DiBP), di-n-butyl phthalate (DnBP) and di(2-ethylhexyl) phthalate (DEHP) were detected. The detection frequency of DnBP and DEHP was more than 90%. The concentrations of total phthalate esters ranged from 0.20 to 8.29 μg m−3 for the gas- phase, from 0.09 to 14.77 μg m−3 for the particle- phase and from 123 to 9504 μg g−1 for the dust- phase. The individual phthalate with the highest concentrations of 6.17 μg m−3, 7.97 μg m−3 and 7228 μg g−1 respectively for gas-, particle- and dust- phase in all investigated rooms is all DiBP. The median concentration of the gas- and particle-phase DiBP (0.52 and 0.72 μg m−3) and dust-phase DEHP (582 μg g−1) were the highest. It was also found that the average concentrations of individual phthalates in residential buildings were often higher than in office buildings, and correlation analysis indicated that DiBP, DnBP and DEHP might come from the same sources. Based on the gas- and particle-phase concentrations measured, the particle-air partition coefficients of phthalates were estimated, and their logarithm values were found to be linearly correlated with the logarithm values of their octanol-air partition coefficients. Finally, the total daily exposure to indoor phthalates in air and dust was calculated, and ranged from 2.6 μg kg−1 day−1 (for adults) to 7.4 μg kg−1 day−1 (for toddlers).