Spatiotemporal patterns and deposition of organophosphate esters (OPEs) in air, foliage and litter in a subtropical forest of South China.

Recent studies revealed the un-negligible impact of airborne organophosphate esters (OPEs) on phosphorus (P)-limited ecosystems. Subtropical forests, the global prevalence P-limited ecosystems, contain canopy structures that can effectively sequester OPEs from the atmosphere. However, little is known about the behavior and fate of OPEs in subtropical forest ecosystem, and the impact on the P cycling in this ecosystem. OPE concentrations in the understory air (at two heights), foliage, and litterfall were investigated in a subtropical forest in southern China. The median ∑OPE concentrations were 3149 and 2489 pg/m3 in the upper and bottom air, respectively. Foliage exhibited higher ∑OPE concentrations (median = 386 ng/g dry weight (dw)) compared to litter (median = 267 ng/g dw). The air OPE concentrations were ordered by broadleaved forest > mixed forest > coniferous forest, which corresponds to the results of canopy coverage or leaf area index. The spatial variation of OPEs in foliage and litter was likely caused by the leaf surface functional traits. Higher OPE concentrations were found in the wet season for understory air while in the dry season for foliage and litter, which were attributed to the changes in emission sources and meteorological conditions, respectively. The inverse temporal variation suggests the un-equilibrium partitioning of OPEs between leaf and air. The OPE concentrations during the litter-incubation presented similar temporal trends with those in foliage and litter, indicating the strong interaction of OPEs between the litter layer and the near-soil air, and the efficient buffer of litter layer played in the OPEs partitioning between soil and air. The median OPEs-associated P deposition fluxes through litterfall were 270, 186, and 249 µg P/m2·yr in the broadleaved, mixed, and coniferous forests, respectively. Although the fluxes accounted for approximately 0.2% of the total atmospheric P deposition, their significance to this P-limited ecosystem may not be negligible.

Factors impacting human exposure to legacy and emerging contaminants in residential dust in Beijing, China: Characteristics of indoor microenvironment.

Exposure to indoor dust is of concern since dust may be contaminated by various toxic chemicals and people spend considerable time indoors. Factors impacting human exposure risks to contaminants in indoor dust may differ from those affecting the loadings of contaminants, but the dominant factors have not yet been well clarified. In this study, the occurrence, human exposure, and related influencing factors of several classes of legacy and emerging contaminants in residential dust across Beijing were investigated, including per- and polyfluoroalkyl substances (PFASs) and three types of flame retardants (FRs), i.e., organophosphate esters (OPEs), polybrominated diphenyl ethers (PBDEs), and novel halogenated FRs (NHFRs). OPEs (median: 3847 ng/g) were the most abundant group, followed by PBDEs (1046 ng/g) and NHFRs (520 ng/g). PFASs (14.3 ng/g) were one to two orders of magnitude lower than FRs. The estimated daily intakes of these contaminants were relatively higher for toddlers than other age groups, with oral ingestion being the main exposure pathway compared with dermal contact. Higher human exposure risks were found in new buildings or newly finished homes due to the elevated intake of emerging contaminants (such as OPEs). Furthermore, higher risks were also found in homes with wooden floors, which were mainly associated with higher levels of PFASs, chloroalkyl and alkyl OPEs, compared with tile floors. Citizens in the urban area also showed higher exposure risks than those in the suburban area. The quantity of household appliances and finishing styles (simple or luxurious) showed an insignificant impact on overall human exposure risks despite their significant effect on the levels of some of the dust contaminants. Results in this study are of importance in understanding human exposure to the co-existence of multiple contaminants in indoor dust.

Spatiotemporal variations, sources, and atmospheric transformation potential of volatile organic compounds in an industrial zone based on high-resolution measurements in three plants.

Industrial emissions are significant sources of volatile organic compounds (VOCs). This study conducted a field campaign at high temporal and spatial resolution to monitor VOCs within three plants in an industrial park in southern China. VOC concentrations showed significant spatial variability in this industrial zone, with median concentrations of 75.22, 40.53, and 29.41 µg/m3 for the total VOCs in the three plants, respectively, with oxygenated VOCs (OVOCs) or aromatics being the major VOCs. Spatial variability within each plant was also significant but VOC-dependent. Seasonal variations in the VOC levels were governed by their industrial emissions, meteorological conditions, and photochemical losses, and they were different for the four groups of VOCs. The temporal and spatial variations in the VOC compositions suggest similar sources of each class of VOCs during different periods of the year in each plant. The diurnal patterns of VOCs (unimodal or bimodal) clearly differed from those at most industrial/urban locations previously, reflecting a dependence on industrial activities. The secondary transformation potential of VOCs also varied temporally and spatially, and aromatics generally made the predominant contributions in this industrial park. The loss rate of OH radicals and ozone formation potential were highly correlated, but the linear relationship substantially changed in summer and autumn due to the intensive emissions of an OVOC species. The lifetime cancer and non-cancer risks via occupational inhalation of the VOCs in the plants were acceptable but merit attention. Taking the secondary transformation potential and health risks into consideration, styrene, xylene, toluene, trichloroethylene, and benzene were proposed to be the priority VOCs regulated in the plants.

Disposable Plastic Waste and Associated Antioxidants and Plasticizers Generated by Online Food Delivery Services in China: National Mass Inventories and Environmental Release.

China's online food delivery (OFD) services consume enormous amounts of disposable plastics. Here, we investigated and modeled the national mass inventories and environmental release of plastics and chemical additives in the plastic. The extra-tree regression identified six key descriptors in determining OFD sales in Chinese cities. Approximately 847 kt of OFD plastic waste was generated in 2021 (per capita 1.10 kg/yr in the megacities and 0.39 kg/yr in other cities). Various additives were extensively detected, with geomean concentrations of 140.96, 4.76, and 0.25 µg/g for ∑8antioxidants, ∑21phthalates, and bisphenol A (BPA), respectively. The estimated mass inventory of these additives in the OFD plastics was 164.7 t, of which 51.1 t was released into the atmosphere via incineration plants and 51.0 t was landfilled. The incineration also released 8.07 t of polycyclic aromatic hydrocarbons and 39.1 kt of particulate matter into the atmosphere. Takeout food may increase the dietary intake of phthalates and BPA by 30% to 50% and raise concerns about considerable exposure to antioxidant transformation products. This study provides profound environmental implications for plastic waste in the Chinese OFD industry. We call for a sustainable circular economy action plan for waste disposal, but mitigating the hazardous substance content and their emissions is urgent.

Complex polycyclic aromatic compound mixtures in PM2.5 in a Chinese megacity: Spatio-temporal variations, toxicity, and source apportionment.

Polycyclic aromatic compounds (PACs) are important toxic organic components in fine particulate matter (PM2.5), whereas the links between PM2.5 toxicity and associated PACs in ambient air are poorly understood. This study investigated the spatial-temporal variations of PACs in PM2.5 collected from 11 sampling sites across a Chinese megacity and characterized the reactive oxygen species (ROS) generation and cytotoxicity induced by organic extracts of PM2.5 based on cellular assays. The extra trees regression model based on machine learning and ridge regression were used to identify the key toxicants among complex PAC mixtures. The total concentrations of these PACs varied from 2.12 to 71.7 ng/m3 across the study city, and polycyclic aromatic hydrocarbons (PAHs) are the main PACs. The spatial variations of the toxicological indicators generally resembled those of the PAC concentrations, and the PM2.5 related to waste treatment facilities exhibited the strongest toxic potencies. The ROS generation was highly correlated with high molecular weight PAHs (MW302 PAHs), followed by PAHs with MW<302 amu and oxygenated PAHs, but not with nitrated PAHs and the plastics additives. The cell mortality showed weak correlations with these organic constituents. The associations between the biological endpoints and these PM2.5-bound contaminants were further confirmed by exposure to authentic chemicals. Four primary sources of PACs were identified, among which coal and biomass combustion sources (30.2% of the total PACs) and industrial sources (31.0%) were predominant. PACs emitted from industrial sources were highly associated with ROS generation in this city. Our findings highlight the potent ROS-generating potential of MW302 PAHs and the importance of industrial sources contributing to PM2.5 toxicity in this megacity, raising public concerns and further administration.

Spatial and temporal change of tetrabromobisphenol A and hexabromocyclododecane in mangrove sediments from the Pearl River Estuary, South China.

Spatial and temporal trends of tetrabromobisphenol (TBBPA) and hexabromocyclododecane (HBCD) in mangrove sediments from the Pearl River Estuary (PRE) in South China were evaluated. Concentrations of TBBPA and HBCD in mangrove sediments ranged from 0.23 to 13.3 and 0.36 to 54.7 ng g-1 dry weight. The highest TBBPA concentration was seen in Guangzhou mangrove wetland near a dockyard and a ferry terminal where TBBPA is utilized in the coatings for the shipbuilding industry. The rapid development of building might elucidate the higher concentrations of HBCD in Shenzhen mangrove sediments. γ-HBCD and α-HBCD was the two main diastereoisomer of HBCD in mangrove sediments with contributions of 56.1 % and 34.0 %. Sediments from the three PRE mangrove ecosystems were selectively enriched for (-)-γ-HBCD. TBBPA concentrations in mangrove sediments from Guangzhou rose during 2012-2015 and declined from 2015 to 2021. HBCD concentrations in the PRE mangrove sediments exhibited an increasing trend from 2012 to 2021.

Human hair as a noninvasive matrix to assess exposure to micro-organic contaminants: State of the art review.

Human biomonitoring has played an important role in assessing human exposure to micro-organic contaminants (MOCs), including chlorinated persistent organic pollutants, brominated flame retardants, organophosphorus flame retardants, non-persistent pesticides, per- and polyfluoroalkyl substances, phthalate esters, bisphenols, and polycyclic aromatic hydrocarbons. Specifically, human hair holds great promise as a noninvasive matrix for MOC biomonitoring. While human hair has been widely used to detect numerous MOCs over recent decades, its reliability of reflecting body burden is still disputable. As a premise for discussion, it is necessary to understand the mechanisms of MOC incorporation into hair from endogenous and exogenous exposures. Then, standardized protocols must be developed to ensure accurate and reliable results. This review article discusses these issues and provides evidence for the reliability of monitoring MOCs in hair by surveying past reports from various categories of MOCs. We find that most persistent organic pollutants - especially those with a higher octanol-water partition coefficient and lower volatility - can be reliably measured using hair analysis, while internal exposure can be accurately measured using MOC metabolites in hair. Finally, we explore the applications of hair analysis in large-scale surveys, retrospective cohort studies, and epidemiological investigations, highlighting the promise of hair analysis in studying the health risks of MOCs.

PM-bound polycyclic aromatic compounds (PACs) in two large-scale petrochemical bases in South China: Spatial variations, sources, and risk assessment.

Polycyclic aromatic compounds (PACs) are potential pollutants emitted from the petrochemical industry, whereas their occurrence and sources in petrochemical regions are still poorly known. The present study revealed the spatial variations, compositional profiles, sources and contributions, and health risks of PM-bound PACs in two large-scale petrochemical bases (GDPB and HNPB) in South China. The concentrations of parent polycyclic aromatic hydrocarbons (PAHs) were 7.14 ± 3.16 ng/m3 for ∑18PAHs and 0.608 ± 0.294 ng/m3 for the PAHs with molecular weight of 302 amu (MW302 PAHs) in the GDPB base and 2.55 ± 1.26 ng/m3 and 0.189 ± 0.088 ng/m3 in the HNPB base. Oxygenated PAHs (OPAHs) showed comparable concentrations to the parent PAHs in both the bases and nitrated PAHs (NPAHs) had the lowest mean levels (260 pg/m3 and 59.4 pg/m3 in the two regions). Coronene, 2,8-dinitrodibenzothiophene, and dibenzo[a,e]fluoranthene showed remarkably higher contributions to the PAC and can be PAC markers of the petrochemical industry source. Five sources of PACs were identified respectively in both petrochemical bases by the positive matrix factorization (PMF) model. The vehicle (and ship) traffic exhaust was the primary source of PACs (contributed 33% to the ∑PACs), and the sources related to the coking of coal and heavy petroleum and refinery exhaust were identified in both bases, with contributions of 10-20%. PACs in GDPB also contributed from secondary atmospheric reactions (17.3%) and the usage of sulfur-containing fuels (20.9%), while the aromatics industry made a significant contribution (20.1%) to the PACs in the HNPB region. The cumulative incremental lifetime cancer risks (ILCRs) induced by inhalation of PM-bound PACs in both petrochemical bases were low (10-8-10-6). For the sources related to the petrochemical industry, coking activities and the aromatic industry were the significant contributors to the ∑ILCRs in GDPB and HNPB, respectively. This research has implications for further source-targeted control and health risk reduction of PACs in petrochemical regions.

Polycyclic aromatic hydrocarbons (PAHs) in air, foliage, and litter in a subtropical forest: Spatioseasonal variations, partitioning, and litter-PAH degradation.

Forest canopies play a vital role in scavenging airborne semi-volatile organic compounds. The present study measured polycyclic aromatic hydrocarbons (PAHs) in the understory air (at two heights), foliage, and litterfall in a subtropical rainforest (the Dinghushan mountain) in southern China. ∑17PAH concentrations in the air ranged from 2.75 to 44.0 ng/m3 (mean = 8.91 ng/m3), showing a spatial variation depending on the forest canopy coverage. Vertical distributions of the understory air concentrations also indicated PAH inputs from the above-canopy air. The concentrations of PAHs in fresh litter (with a mean of 261 ± 163 ng/g dry weight (dw)) were slightly lower than those in the foliage (362 ± 291 ng/g dw). Unlike the stable air PAH concentrations for most of the time of the year, the temporal variations of foliage and litter concentrations were remarkable but generally similar. Higher or comparable leaf/litter-air partition coefficients (KLA) in fresh litter compared with living KLA in leaves suggest that the forest litter layer is an efficient storage media for PAHs. Degradation of three-ring PAHs in litter under the field conditions follows first-order kinetics (R2 = 0.81), while the degradation is moderate for four-ring PAHs and insignificant for five- and six-ring PAHs. The yearly net cumulative deposition of PAHs through forest litterfall in the whole Dinghushan forest area over the sampling year was about 1.1 kg, 46% of the initial deposition (2.4 kg). This spatial variations study provides the results of in-field degradation of litter PAHs and makes a quantitative assessment of the litter deposition of PAHs, deducing their residence dynamics in the litter layer in a subtropical rainforest.

Accumulation and translocation of traditional and novel organophosphate esters and phthalic acid esters in plants during the whole life cycle.

Organophosphate esters (OPEs) and phthalic acid esters (PAEs) are widespread contaminants in the environment. The variations of these chemicals in plants throughout their life cycle is little known. In this study, OPEs, OPE metabolites, and PAEs in peanut and corn grown under field conditions, soil, and air were measured to understand the uptake and translocation, distributions in the plant compartments, and metabolism in the plants. The soil concentrations showed an enrichment effect of OPEs onto the rhizosphere soil but a depletion effect of PAEs on rhizosphere soils. The PAE concentrations between peanut (with a mean of 1295 ng/g dw) and corn (3339 ng/g dw) were significantly different, but the OPE concentrations were not significantly different (with means of 15.6 and 19.2 ng/g dw, respectively). OPE metabolites were also detected in the plants, with lower concentrations and detection rates. Similarities and differences in the temporal variations of the concentrations of traditional OPEs, novel OPEs, and PAEs in plants during their growth were observed. The variations were dependent on both plant species and particular tissues. The leaf compartment is the most important reservoir of OPEs and PAEs (but not OPE metabolites) for both species, highlighting the importance of an aerial uptake pathway. The chemicals have a low potential to be translocated into peanut and corn kernels, reducing their risks via food consumption. Less hydrophobic compounds have higher root concentration factors in this study. These observations differ from those of previous hydroponic experiments.

Particle size-resolved emission characteristics of complex polycyclic aromatic hydrocarbon (PAH) mixtures from various combustion sources.

Combustion of domestic solid fuels is a significant source of polycyclic aromatic hydrocarbons (PAHs). Some oxygenated PAHs (o-PAHs) and PAHs with molecular weight of 302 (MW302 PAHs) are more toxic than the traditional 16 priority PAHs, whereas their emissions were much less elucidated. This study characterized the size-dependent emissions of parent PAHs (p-PAHs), o-PAHs, and MW302 PAHs from various combustion sources. The estimated emission factors (eEFs) from biomass burning sources were highest for most of the PAHs (391-8928 µg/kg), much higher than that of anthracite coal combustion (43.0-145 µg/kg), both which were operated in an indoor stove. Cigarette smoking had a high eEF of o-PAHs (240 ng/g). MW302 PAHs were not found in the emissions of smoking, cooking, and vehicular exhausts. Particle-size distributions of PAHs were compound- and source-dependent, and the tendency to associate with smaller particles was observed especially in biomass burning and cigarette smoking sources. Furthermore, the inter-source differences in PAH eEFs were associated with their dominance in fine particles. PAH composition profiles also varied with the particle size, showing increasing contributions of large-molecule PAHs with decreasing sizes in most cases. The size distributions of p-PAHs are much more significantly dependent on their n-octanol/air partition coefficients and vapor pressures than those of o-PAHs, suggesting differences in mechanisms governing their distributions. Several molecular diagnostic ratios (MDRs), including two based on MW302 PAHs, specific to these combustion scenarios were identified. However, the MDRs within some sources are also strongly size-dependent, providing a new explanation for the uncertainty in their application for source identification of PAHs. This work also highlights the necessity for understanding the size-resolved atmospheric behaviors and fate of PAHs after their emission.

PM2.5-bound phthalates and phthalate substitutes in a megacity of southern China: spatioseasonal variations, source apportionment, and risk assessment.

Plasticizers are ubiquitous pollutants in the environment, whereas few efforts have been made to elucidate their emission sources in the atmosphere. In this research, the spatioseasonal variations and sources of particle-bound (PM2.5) phthalates (PAEs) and their substitutes (APs) at residential sites in seven districts and at four potential point-source sites across a megacity in South China were revealed. The total concentrations of PAEs ranging from 10.7 to 528 ng/m3 were substantially higher than those of APs (1.45.58.5 ng/m3). Significant spatial variations in the concentrations of the pollutants were observed, which were generally higher at the sites with intensive industrial activities and the point-source sites. Most atmospheric plasticizer levels peaked in summer, probably due to the temperature-promoted volatilization. Seven sources of plasticizers were identified by the positive matrix factorization (PMF) model. The sources in less industrialized districts are mainly associated with domestic and commercial emissions and with industry in the industrialized districts. Specifically, plastics and personal care products together contributed 60% of the plasticizers in the atmosphere of this city, followed by solvents and polyester industry sources. The incremental lifetime cancer risk of inhalation exposure to bis(2-ethylhexyl) phthalate in the study city is below the acceptable level. Relatively higher risks were found for residents living around sites with intensive industrial activities and around wastewater treatment plant.

Changes in human hair levels of organic contaminants reflecting China's regulations on electronic waste recycling.

To assess the impacts of regulations and laws enhancing the management of e-waste in China, hair samples of local residents and dismantling workers in a former e-waste area in 2016 and 2019, five and eight years after the implementation of legislation and regulations in this area since 2011, respectively. The temporal changes in levels of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and organophosphorus flame retardants (OPFRs) in the hair samples were investigated. Besides, the levels of these organic contaminants in hair samples collected from the same area in 2009, 2011, and 2015 reported in previous studies were used as comparison. The highest median levels of Σ9PCBs (719 ng/g), Σ3Penta-BDEs (16.1 ng/g), and Σ3Octa-BDEs (8.46 ng/g) in hair were found in 2011, with a significant decrease trend was observed from 2011 to 2019 (p < 0.05). As for Deca-BDE, the levels reached the maximum in 2015 (133 ng/g), following by a significant decrease to 2016 (7.46 ng/g) and 2019 (2.61 ng/g) (p < 0.05). The median levels of Σ8OPFRs, also decreased significantly (p < 0.05) from 2015 (357 ng/g) to 2016 (264 ng/g) and 2019 (112 ng/g). Moreover, a significantly increasing trend was observed for the ratios of triphenyl phosphate (TPHP) and tris(2-chloropropyl) phosphate (TCIPP), two predominant OPFRs, to Deca-BDE from 2015 to 2019 (p < 0.01), suggesting a shift of "legacy" to "emerging" contaminants released from e-waste recycling in this area. The temporal changes in hair levels of typical organic contaminants in residents and dismantling workers indicated the effectiveness of the regulations on informal e-waste recycling activities and solid waste in China.

Semi-volatile organic compounds in fine particulate matter on a tropical island in the South China Sea.

Measurements of hazardous semi-volatile organic compounds (SVOCs) in remote tropical regions are rare. In this study, polycyclic aromatic compounds (PACs) [including polycyclic aromatic hydrocarbons (PAHs), nitrated PAHs (NPAHs), and oxygenated PAHs (OPAHs)], organophosphate esters (OPEs), and phthalic acid esters (PAEs) were measured in fine particulate matter (PM2.5) at Yongxing Island in the South China Sea (SCS). The concentrations of PACs (median = 53.5 pg/m3) were substantially low compared with previous measurements. The concentration weighted trajectory (CWT) model showed that the eastern and southern China was the main source region of PAC, occurring largely during the northeast (NE) monsoon. The PM2.5 showed remarkably high concentrations of OPEs (median = 3231 pg/m3) and moderate concentrations of PAEs (13,013 pg/m3). Some Southeast Asian countries were largely responsible for their higher concentrations, driven by the tropical SCS monsoons. We found significant atmospheric loss of the SVOCs, which is an explanation for the low concentrations of PACs. Enhanced formation of N/OPAHs originated from tropical regions was also observed. The positive matrix factorization model was applied to apportion the SVOC sources. The results, as well as correlation analyses of the SVOC concentrations, further indicate insignificant local sources and enhanced atmospheric reactions on this island.

Polyhalogenated carbazoles in freshwater and estuarine sediment from China and the United States: A multi-regional study.

The present study represents a multi-regional investigation of polyhalogenated carbazoles (PHCZs) contamination in estuarine and freshwater systems from the United States and China. Although recent studies have suggested that PHCZs are persistent and bioaccumulative, available data are not sufficient to understand their large-scale spatial and temporal distributions in the environment. The present study investigated spatial distributions of PHCZs in surface sediment from multiple freshwater and estuarine systems located in China and the United States (U.S.) during the period of 2012-2017, as well as temporal distributions from vertical trends in selected sediment cores. The results demonstrated large variations of PHCZ contamination across regions, with median concentrations of ΣPHCZs in surface sediment ranging from 3.1 to 134 ng/g. Profiles of PHCZ congener composition also exhibited regional variations and estuarine-freshwater differences. These differences likely reflect the relative contributions of different natural and industrial sources among the locations. Vertical profiles of concentrations and compositions in one Chinese estuarine sediment core and two freshwater sediment cores from the U.S. all demonstrated clear anthropogenic influences to varying degrees. Toxic equivalents (TEQ) of PHCZs were estimated based on their dioxin-like activities, which ranged from <0.001 to 4.94 pg TEQ/g in all sites. The results suggest that PHCZs could add additional ecological risks to the benthos and other aquatic organisms. Our findings constitute an essential contribution to the knowledge body of PHCZ contamination in global aquatic systems and congener-specific contamination characterizations.

Effects of carbonaceous materials and particle size on oral and inhalation bioaccessibility of PAHs and OPEs in airborne particles.

Bioavailability of environmental contaminants is attracting considerable scientific attention due to growing awareness of its importance for risk assessment. In this study, size-segregated airborne particles were collected from six point-source sites, an urban residential site, and a sub-urban site. Potential factors governing bioaccessibility of the particle-bound polycyclic aromatic hydrocarbons (PAHs) and organophosphorus esters (OPEs) in stimulated gastrointestinal and respiratory tracts were elucidated. Particle concentrations of PAHs and OPEs at the eight sites were 2.4-32.3 ng/m3 and 1.6-19.9 ng/m3, respectively. In fine particles (with aerodynamic diameter less than 2.5 µm), 4- to 6-ring PAHs were more strongly correlated with organic carbon (OC) than elemental carbon (EC); while 3- and 4-ring PAHs in coarse particles (2.5-10 µm) tended to associate with EC. OPEs mostly showed significant correlations with EC in both fine and coarse particles. OC and EC exerted a significantly restraining effect on the oral and inhalation bioaccessibility of most hydrophobic organic contaminants (HOCs) in fine particles due to sorption of HOC molecules to these components. Furthermore, the effects varied, which could depend either on the emission sources (for oral bioaccessibility of PAHs) or the physicochemical properties of HOCs (for bioaccessibility of OPEs and inhalation bioaccessibility of PAHs). Linear regression between OC/EC contents and HOC bioaccessibility indicated that EC should play a more important role in the inhalation bioaccessibility than the oral bioaccessibility. Particle size of airborne particles is a relatively less significant factor determining the bioaccessibility.

Traditional and novel organophosphate esters (OPEs) in PM2.5 of a megacity, southern China: Spatioseasonal variations, sources, and influencing factors.

Organophosphate esters (OPEs) are ubiquitous contaminants in the environment, whereas their atmospheric processes and fate are poorly understood. The present study revealed the spatial heterogeneity and seasonal variations of traditional and novel OPEs in PM2.5 (particulate matter with diameters < 2.5 µm) across a megacity (including residential areas and potential source sites) in South China. Potential influencing factors on the contamination levels of OPEs were addressed. The total concentrations of 11 traditional OPEs ranging from 262 to 42,194 pg/m3 (median = 1872 pg/m3) were substantially higher than those of 10 novel OPEs (33.5-3835 pg/m3, median = 318 pg/m3). Significant spatial and temporal variations in the concentrations of most OPEs were observed. The overall district-specific contamination levels in this city showed dependence on the secondary industry sector for non-predominant OPEs and on the tertiary industry for predominant OPEs. The seasonal variations of the OPE concentrations suggest difference in their sources or influence of meteorological conditions. The correlations between the individual OPEs in PM2.5 are determined largely by either their applications or physicochemical properties (in particular vapor pressure). The correlations between OPE concentrations and each meteorological factor (temperature, relative humidity, wind speed, and surface solar radiation) were inconsistent (positive and negative). Wind speed had the greatest effect on the OPE levels; While most OPEs bound to PM2.5 were not efficiently scavenged by below-cloud rainfall. The results suggest that atmospheric half-life and Henry's Law Constant of OPEs are also determining factors for the wind speed and rainfall influence, respectively. However, mechanisms underlying the influence of meteorological conditions on atmospheric OPEs still need further research.

Characterization of airborne particles and cytotoxicity to a human lung cancer cell line in Guangzhou, China.

Air pollution by airborne particles is a serious health problem worldwide. The present study was aimed at investigating the concentrations and composition of total suspended particles (TSPs) and PM2.5 at various industrial/commercial sites of Guangzhou, a megacity of Southern China. Major and trace elements, ions and carbonaceous fraction were determined and main components were calculated. In addition, in order to assess the potential toxic on the respiratory system of these PM, cytotoxicity of size-fractionated particles (PM10-5.6, PM5.6-3.3, PM3.3-1.1, PM1.1-0.43) for a human lung cancer cell line (A549) was also investigated. Correlations between PM constituents and toxicity were assessed. Median levels of TSPs and PM2.5 in industrial/commercial sites were 206 and 57.7 µg/m3, respectively. Nickel, Cu, Mo, Mn, Pb, and Ti were the most abundant metals in TSPs and PM2.5. Industrial activities and coal combustion were the most important sources of carbonaceous particles in the zone. MTT assays showed that PM10-5.6 and PM1.1-0.43 had the highest and the lowest cytotoxicity to A549 cell lines, respectively. Inhalable particles around the manufacturing of metal facilities and formal waste treatment plants showed a high cytotoxicity to A549 cell lines. In general terms, no significant correlations were found between main components of PM and toxicity. However, W showed a significant correlation with cell viability.

Brominated flame retardants (BFRs) in PM2.5 associated with various source sectors in southern China.

The present study investigates legacy and novel brominated flame retardants (BFRs) in atmospheric PM2.5 associated with various urban source sectors in a city and electronic waste (e-waste) recycling facilities in southern China. The concentrations of polybrominated diphenyl ethers (PBDEs) and novel BFRs (∑2NBFRs) at the urban industrial park (UIP) sites varied greatly from 22.0 to 105 pg m-3 and from to 29.7 to 459 pg m-3, respectively, and higher concentrations were generally found at sites involving industrial sectors of electronics, plastics, and machinery. Their spatial variations at other urban potential source sites were small suggesting a lack of strong point emissions. The levels of PBDEs and ∑2NBFRs at the e-waste facilities (220-2356 pg m-3 and 83.6-569 pg m-3) were significantly higher and did not temporally decline, indicating that improvement in e-waste recycling techniques does not significantly reduce emissions of PBDEs. NBFRs dominated the BFRs at the urban sites (55% on average), while PBDEs were still dominant (78%) at the e-waste sites. PBDE congener profiles in PM2.5 were substantially different from those in commercial mixtures. The congener profiles as well as their correlations suggested frequent formation of lower brominated PBDEs from degradation of highly brominated congeners in this region, which became appreciable due to the reduced emissions. The significant correlations among the lower brominated congeners also reflected similar environmental behaviors due to similar physicochemical properties.

Brominated and phosphate flame retardants from interior and surface dust of personal computers: insights into sources for human dermal exposure.

It remains unclear whether internal or external sources play the more significant role in flame retardant (FR) contamination of surface dust from personal computers (PCs), which may lead to bias on dermal exposure assessment of FRs. In the present study, the occurrence and profiles of several brominated and phosphate FRs were measured in the interior dust, and the upper surface (keyboard) and bottom surface (bottom cover) wipes of PCs. BDE 209 (639 ng/g), decabromodiphenyl ethane (DBDPE, 885 ng/g), and triphenyl phosphate (TPHP, 1880 ng/g) were the most abundant chemicals in interior PC dust, while tris(2-chloroisopropyl) phosphate (TCIPP), TPHP, and DBDPE were dominant on both surfaces of PCs. No significant correlation between interior dust and both PC surfaces was observed for concentrations of most FRs except BDE 183. Different sources of FRs for interior and surface dust of PCs were further revealed by principal component analysis (PCA). FRs from external sources, rather than emission from inner PC components, are likely the main contributor for FR profiles on PC surfaces. Exposure assessment results demonstrated a minor contribution from PC dermal contact, compared with hand-to-mouth uptake, to total exposure. The applicability of surface wipes to assess dermal exposure to FR-treated products needs to be further investigated.