Emission of poly and perfluoroalkyl substances, UV-filters and siloxanes to air from wastewater treatment plants

Assessing the impact of mining on cyclic and linear methylsiloxane distribution in Tibetan soils: Source contribution and transport pattern

The pervasive presence of methylsiloxanes (MSs), comprising linear and cyclic congeners, in the environment poses significant ecological risks, yet the understanding of their transport mechanisms and deposition patterns remains limited. This study analyzed the concentrations of 12 linear-MSs (L3-L14) and 7 cyclic-MSs (D3-D9) in 29 surface soil samples collected across varying altitudes (3726 to 4863 m) near the Jiama mining sector in Tibet, aiming to investigate the distribution and transport dynamics of MSs from the emission source. The distribution of total MS concentration (ranging from 50.1 to 593 ng/g) showed a remarkable correlation with proximity to the mining site, suggesting the emergent source of mining activities for the MSs in the remote environment of the Tibetan Plateau. Employing the innovative model of robust absolute principal component scores-robust geographically weighted regression (RAPCS-RGWR), the analysis predicted that the mining operations contributing 57.1 % of the total soil MSs, would significantly surpass contributions from traffic emissions (14.7 %), residential activities (13.2 %), and the environmental factor of total organic matter content (14.9 %). The Boltzmann equation effectively modeled the distribution pattern of soil MSs, highlighting atmospheric transport and gravitational settling as key distribution mechanisms. However, linear-MSs exhibited longer transport distances than cyclic-MSs and were more profoundly affected by prevailing wind directions, suggesting their differential environmental behaviors and risks. Our study underscored that the mining sector possibly emerged as a significant source of Tibetan MSs, and provided insights into the transport and fate of MSs in remote, high-altitude environments. The findings emphasize the need for targeted pollution control strategies to mitigate the environmental footprint of mining activities in Tibet and similar regions.

A review of sample collection and analytical methods for detecting per- and polyfluoroalkyl substances in indoor and outdoor air

Per- and polyfluoroalkyl substances (PFAS) are a unique class of chemicals synthesized to aid in industrial processes, fire-fighting products, and to benefit consumer products such as clothing, cosmetics, textiles, carpets, and coatings. The widespread use of PFAS and their strong carbon-fluorine bonds has led to their ubiquitous presence throughout the world. Airborne transport of PFAS throughout the atmosphere has also contributed to environmental pollution. Due to the potential environmental and human exposure concerns of some PFAS, research has extensively focused on water, soil, and organismal detection, but the presence of PFAS in the air has become an area of growing concern. Methods to measure polar PFAS in various matrices have been established, while the investigation of polar and nonpolar PFAS in air is still in its early development. This literature review aims to present the last two decades of research characterizing PFAS in outdoor and indoor air, focusing on active and passive air sampling and analytical methods. The PFAS classes targeted and detected in air samples include fluorotelomer alcohols (FTOHs), perfluoroalkane sulfonamides (FASAs), perfluoroalkane sulfonamido ethanols (FASEs), perfluorinated carboxylic acids (PFCAs), and perfluorinated sulfonic acids (PFSAs). Although the manufacturing of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) has been largely phased out, these two PFAS are still often detected in air samples. Additionally, recent estimates indicate that there are thousands of PFAS that are likely present in the air that are not currently monitored in air methods. Advances in air sampling methods are needed to fully characterize the atmospheric transport of PFAS.

Occurrence, seasonal variations, and fate of household and personal care chemicals in a wastewater treatment plant with Bacillus bioreactor process

Household and personal care chemicals (HPCCs) constitute a significant component of everyday products, with their global usage on the rise. HPCCs are eventually discharged into municipal wastewater treatment plants (WWTPs). However, the behaviors of HPCCs inside the Bacillus Bioreactor (BBR) process, including their prevalence, fate, and elimination mechanisms, remain underexplored. Addressing this gap, our study delves into samples collected from a BBR process at a significant WWTP in the northeast of China. Our results spotlight the dominance of linear alkylbenzene sulfonates (LASs) in the influent with concentrations ranging between 238 and 789 μg/L, much higher than the other HPCC concentrations, and remained dominant in the subsequent treatment units. After treatment using the BBR process, the concentrations of HPCCs in the effluent were diminished. Examination of different treatment units underscores the grit chamber removed over 60% of higher-concentration HPCCs, while the performance of the (RBC) tank needs to be improved. Except for the ultraviolet radiation (UV)-filters, seasonal variations exert minimal impact on the concentrations and removal efficiencies of other HPCCs in the BBR process. According to the mass balance analysis, the important mechanisms for HPCC removal were biodegradation and sludge adsorption. Also, the octocrylene (OCT) concerns raised by the environmental risk assessment of the HPCCs residuals in the final effluent, indicate a moderate risk to the surrounding aquatic environment (0.1 < RQ < 1), whereas other HPCCs have a lower risk level (RQ < 0.1). Overall, the research offers new perspectives on the fate and elimination mechanisms of HPCCs throughout the BBR process.

Assessing Contributions of Synthetic Musk Compounds from Wastewater Treatment Plants to Atmospheric and Aquatic Environments

The high environmental concentrations, persistence, and toxicity of synthetic musk compounds (SMCs) necessitate a better grasp of their fate in wastewater treatment plants (WWTPs). To investigate the importance of WWTPs as pathways of SMCs to the environment, air and wastewater samples were collected at four WWTPs in Ontario, Canada. Polycyclic musks (PCMs) were present at higher concentrations than nitro musks (NMs) and macrocyclic musks (MCMs). Three PCMs [galaxolide (HHCB), tonalide (AHTN), and iso-E super (OTNE)] were the most abundant compounds (0.30-680 ng/m3 in air, 0.40-15 μg/L in influent, and 0.007-6.0 μg/L in effluent). Analyses of multiyear data suggest that risk management measures put in place have been effective in reducing the release of many SMCs into the environment. The highest removal efficiency, up to almost 100% of some SMCs, was observed for the plant with the longest solid retention time. A fugacity-based model was established to simulate the transport and fate of SMCs in the WWTP, and good agreement was obtained between the measured and modeled values. These findings indicate that the levels of certain SMCs discharged into the atmospheric and aquatic environments were substantial, potentially resulting in exposure to both humans and wildlife.

Fate of perfluoroalkyl and polyfluoroalkyl substances (PFAS) through two full-scale wastewater sludge incinerators

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are an emerging issue in wastewater treatment. High-temperature thermal processes, incineration being time-tested, offer the opportunity to destroy and change the composition of PFAS. The fate of PFAS has been documented through wastewater sludge incinerators, including a multiple hearth furnace (MHF) and a fluidized bed furnace (FBF). The dewatered wastewater sludge feedstock averaged 247- and 1280-μmol targeted PFAS per sample run in MHF and FBF feed, respectively. Stack emissions (reportable for all targeted PFAS from MHF only) averaged 5% of that value with shorter alkyl chain compounds comprising the majority of the targeted PFAS. Wet scrubber water streams accumulated nonpolar fluorinated organics from the furnace exhaust with an average of 0.740- and 0.114-mol F- per sample run, for the MHF and FBF, respectively. Simple alkane PFAS measured at the stack represented 0.5%-4.5% of the total estimated facility greenhouse gas emissions. PRACTITIONER POINTS: The MHF emitted six short chain PFAS from the stack, which were shorter alkyl chain compounds compared with sludge PFAS. The FBF did not consistently emit reportable PFAS from the stack, but contamination complicated the assessment. Five percent of the MHF sludge molar PFAS load was reported in the stack. MHF and FBF wet scrubber water streams accumulated nonpolar fluorinated organics from the furnace exhaust. Ultra-short volatile alkane PFAS measured at the stack represented 0.5%-4.5% of the estimated facility greenhouse gas emissions.

Helping WWTP managers to address the volatile methylsiloxanes issue-Behaviour and complete mass balance in a conventional plant

Volatile methylsiloxanes (VMSs) are a group of additives employed in different consumer products that can affect the quality of the biogas produced in wastewater treatment plants (WWTPs). The main objective of this study is to understand the fate of different VMSs along the treatment process of a WWTP located in Aveiro (Portugal). Thus, wastewater, sludge, biogas, and air were sampled in different units for two weeks. Subsequently, these samples were extracted and analyzed by different environment-friendly protocols to obtain their VMS (L3-L5, D3-D6) concentrations and profiles. Finally, considering the different matrix flows at every sampling moment, the mass distribution of VMSs within the plant was estimated. The levels of ∑VMSs were similar to those showed in the literature (0.1-50 μg/L in entry wastewater and 1-100 μg/g dw in primary sludge). However, the entry wastewater profile showed higher variability in D3 concentrations (from non detected to 49 μg/L) than found in previous studies (0.10-1.00 μg/L), likely caused by isolated releases of this compound that could be related to industrial sources. Outdoor air samples showed a prevalence of D5, while indoor air locations were characterized by a predominance of D3 and D4. Differences in sources and the presence of an indoor air filtration system may explain this divergence. Biogas was characterized by ∑VMSs concentrations (8.00 ± 0.22 mg/m3) above the limits recommended by some engine manufacturers and mainly composed of D5 (89%). Overall, 81% of the total incoming mass of VMSs is reduced along the WWTP, being the primary decanter and the secondary treatment responsible for the highest decrease (30.6% and 29.4% of the initial mass, respectively). This reduction, however, is congener dependant. The present study demonstrates the importance of extending sampling periods and matrices (i.e., sludge and air) to improve sample representativity, time-sensitivity, and the accuracy of mass balance exercises.

Developing Methods for Assessing Trophic Magnification of Perfluoroalkyl Substances within an Urban Terrestrial Avian Food Web

We investigated the trophic magnification potential of perfluoroalkyl substances (PFAS) in a terrestrial food web by using a chemical activity-based approach, which involved normalizing concentrations of PFAS in biota to their relative biochemical composition in order to provide a thermodynamically accurate basis for comparing concentrations of PFAS in biota. Samples of hawk eggs, songbird tissues, and invertebrates were collected and analyzed for concentrations of 18 perfluoroalkyl acids (PFAAs) and for polar lipid, neutral lipid, total protein, albumin, and water content. Estimated mass fractions of PFCA C8-C11 and PFSA C4-C8 predominantly occurred in albumin within biota samples from the food web with smaller estimated fractions in polar lipids > structural proteins > neutral lipids and insignificant amounts in water. Estimated mass fractions of longer-chained PFAS (i.e., C12-C16) mainly occurred in polar lipids with smaller estimated fractions in albumin > structural proteins > neutral lipids > and water. Chemical activity-based TMFs indicated that PFNA, PFDA, PFUdA, PFDoA, PFTrDA, PFTeDA, PFOS, and PFDS biomagnified in the food web; PFOA, PFHxDA, and PFHxS did not appear to biomagnify; and PFBS biodiluted. Chemical activity-based TMFs for PFCA C8-C11 and PFSA C4-C8 were in good agreement with corresponding TMFs derived with concentrations normalized to only total protein in biota, suggesting that concentrations normalized to total protein may be appropriate proxies of chemical activity-based TMFs for PFAS, which predominantly partition to albumin. Similarly, TMFs derived with concentrations normalized to albumin may be suitable proxies of chemical activity-based TMFs for longer-chained PFAS, which predominantly partition to polar lipids.

Per- and polyfluoroalkyl substances fate and transport at a wastewater treatment plant with a collocated sewage sludge incinerator

This study aims to understand the fate and transport of per- and polyfluoroalkyl substances (PFAS) and inorganic fluoride (IF) at an undisclosed municipal wastewater treatment plant (WWTP) operating a sewage sludge incinerator (SSI). A robust statistical analysis characterized concentrations and mass flows at all WWTP and SSI primary influents/effluents, including thermal-treatment derived airborne emissions. WWTP-level net mass flows (NMFs) of total PFAS were not statistically different from zero. SSI-level NMFs indicate that PFAS, and specifically perfluoroalkyl acids (PFAAs), are being broken down. The NMF of perfluoroalkyl sulfonic acids (PFSAs; -274 ± 34 mg/day) was statistically significant. The observed breakdown primarily occurred in the sewage sludge. However, the total PFAS destruction and removal efficiency of 51 % indicates the SSI may inadequately remove PFAS. The statistically significant IF source (NMF = 16 ± 4.2 kg/day) compared to the sink of PFAS as fluoride (NMF = -0.00036 kg/day) suggests that other fluorine-containing substances are breaking down in the SSI. WWTP PFAS mass discharges were primarily to the aquatic environment (>99 %), with <0.5 % emitted to the atmosphere/landfill. Emission rates for formerly phased-out PFOS and PFOA were compared to previously reported levels. Given the environmental persistence of these compounds, the observed decreases in PFOS and PFOA discharge rates from prior reports implies regional/local differences in emissions or possibly their accumulation elsewhere. PFAS were observed in stack gas emissions, but modestly contributed to NMFs and showed negligible contribution to ambient air concentrations observed downwind.

Per- and polyfluoroalkyl substances and volatile methyl siloxanes in global air: Spatial and temporal trends

The study reports on the atmospheric concentrations of per- and polyfluoroalkyl substances (PFAS) and volatile methyl siloxanes (VMS) measured using sorbent-impregnated polyurethane foam disks (SIPs) passive air samplers. New results are reported for samples collected in 2017, which extends temporal trend information to the period 2009-2017, for 21 sites where SIPs have been deployed since 2009. Among neutral PFAS, fluorotelomer alcohols (FTOHs) had higher concentrations than perfluoroalkane sulfonamides (FOSAs) and perfluoroalkane sulfonamido ethanols (FOSEs) with levels of ND‒228, ND‒15.8, ND‒10.4 pg/m³, respectively. Among ionizable PFAS, the sum of perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl sulfonic acids (PFSAs) in air were 0.128-781 and 6.85-124 pg/m³, respectively. Longer-chain i.e. C₉-C₁₄ PFAS, which are relevant to the recent proposal by Canada for a listing of long-chain (C₉-C₂₁) PFCAs to the Stockholm Convention, were also detected in the environment at all site categories including Arctic sites. Cyclic and linear VMS ranged between 1.34‒452 and 0.01-12.1 ng/m³, respectively, showing dominance in urban areas. Despite the wide range of levels observed across different site categories, geometric means of the PFAS and VMS groups were fairly similar when grouped according to the five United Nations regions. Variable temporal trends in air (2009-2017) were observed for both PFAS and VMS. PFOS, which has been listed in the Stockholm Convention since 2009, is still showing increasing tendencies at several sites, indicating constant input from direct and/or indirect sources. These new data inform international chemicals management for PFAS and VMS.

Seasonal occurrence, concentrations, and occupational exposure to VMSs in different environments of a WWTP

In the present study, indoor and outdoor environments of a wastewater treatment plant (WWTP) were monitored by passive air samplers to assess the presence and seasonal trends of three linear (L3-L5) and four cyclic (D3-D6) volatile methylsiloxanes (VMSs). Furthermore, passive sampling rates (PSRs) were estimated from literature values to calculate VMSs air concentrations and occupational exposure to potentially toxic (D4-D6) congeners. Results showed a seasonal pattern of VMSs in outdoor locations (especially in the aeration tank and preliminary treatment), being the highest levels of total VMSs reached in Summer and the lowest in Spring, caused by the confluence of changing weather conditions and VMSs consumption patterns. This seasonality was not found in indoor sites. The congener profiles of VMSs were consistent throughout the year, showing a prevalence of D5 outdoors, and of D3 and D4 in strictly indoor environments. Different sources of VMSs, together with an air filtering system installed in the sampled buildings explain these differences. Estimated PSRs yielded lower values indoors (0.16-0.21 m³/day) than outdoors (0.32-0.49 m³/day), due to different wind speeds. Overall, outdoor locations showed higher VMSs concentrations in air than indoors. However, the values detected in both environments (∑VMSs between 8.00 and 2000 ng/m³) were within the ranges described in the literature for these locations. The occupational exposure to D4-D6 estimated for three different activities in the WWTP showed the highest values for Maintenance Technicians (8010 ± 722 ng/(kg·year)) and the lowest for Laboratory Technicians (5410 ± 874 ng/(kg·year)), in direct correlation with the higher amount of time spent outdoors by the former. In any case, the exposure was below the inhalation threshold of 150 μg/(kg·day) proposed as safe by other authors.

Use and release of per- and polyfluoroalkyl substances (PFASs) in consumer food packaging in U.S. and Canada

Numerous per- and polyfluoroalkyl substances (PFASs) occur in consumer food packaging due to intentional and unintentional addition, despite increasing concern about their health and environmental hazards. We present a substance flow analysis framework to assess the flows of PFASs contained in plant fiber-based and plastic food packaging to the waste stream and environment. Each year between 2018 and 2020, an estimated 9000 (range 1100-25 000) and 940 (range 120-2600) tonnes per year of polymeric PFASs were used in 2% of food packaging in the U.S. and Canada, respectively. At least 11 tonnes per year of non-polymeric PFASs also moved through the food packaging life cycle. Approximately 6100 (range 690-13 000) and 700 (range 70-1600) tonnes per year of these PFASs were landfilled or entered composting facilities in the U.S. and Canada, respectively, with the potential to contaminate the environment. The results suggest that minimal food packaging contains intentionally added PFASs which, nonetheless, has the potential to contaminate the entire waste stream. Further, this indicates that PFASs are not needed for most food packaging. These results serve as a benchmark to judge the effectiveness of future industry and government initiatives to limit PFAS use in food packaging.

Beach showers as sources of contamination for sunscreen pollution in marine protected areas and areas of intensive beach tourism in Hawaii, USA

In 2019, sands in nearby runoff streams from public beach showers were sampled on three islands in the State of Hawaii and tested for over 18 different petrochemical UV filters. Beach sands that are directly in the plume discharge of beach showers on three of the islands of Hawaii (Maui, Oahu, Hawai'i) were found to be contaminated with a wide array of petrochemical-based UV-filters that are found in sunscreens. Sands from beach showers across all three islands had a mean concentration of 5619 ng/g of oxybenzone with the highest concentration of 34,518 ng/g of oxybenzone at a beach shower in the Waikiki area of Honolulu. Octocrylene was detected at a majority of the beach shower locations, with a mean concentration of 296.3 ng/g across 13 sampling sites with the highest concentration of 1075 ng/g at the beach shower in Waikiki. Avobenzone, octinoxate, 4-methylbenzylidene camphor and benzophenone-2 were detected, as well as breakdown products of oxybenzone, including benzophenone-1, 2,2'-dihydroxy-4-methoxybenzophenone, and 4-hydroxybenzophenone. Dioxybenzone (DHMB) presented the highest concentration in water (75.4 ng/mL), whereas octocrylene was detected in all water samples. Some of these same target analytes were detected in water samples on coral reefs that are adjacent to the beach showers. Risk assessments for both sand and water samples at a majority of the sampling sites had a Risk Quotient > 1, indicating that these chemicals could pose a serious threat to beach zones and coral reef habitats. There are almost a dozen mitigation options that could be employed to quickly reduce contaminant loads associated with discharges from these beach showers, like those currently being employed (post-study sampling and analysis) in the State of Hawaii, including banning the use of sunscreens using petrochemical-based UV filters or educating tourists before they arrive on the beach.

Application of multimedia models for understanding the environmental behavior of volatile methylsiloxanes: Fate, transport, and bioaccumulation

Multimedia fate and transport models (MFTMs) describe how chemicals behave in the environment based on their inherent properties and the characteristics of receiving systems. We critically review the use of MFTMs for understanding the behavior of volatile methylsiloxanes (VMS). MFTMs have been used to predict the fate of VMS in wastewater treatment, rivers, lakes, marine systems, and the atmosphere, and to assess bioaccumulation and trophic transfers. More widely, they have been used to assess the overall persistence, long-range transport potential (LRTP), and the propensity for atmosphere-surface exchange. The application of MFTMs for VMS requires particularly careful selection of model inputs because the properties of VMS differ from those of most organic compounds. For example, although n-octanol/water partition coefficient (K_OW ) values are high, air:water partition coefficient (K_AW ) values are also high and n-octanol/air partition coefficient (K_OA ) values are relatively low. In addition, organic carbon/water partition coefficient (K_OC ) values are substantially lower than expectations based on K_OW . This means that most empirical relationships between K_OC and K_OW are not appropriate. Good agreement between modeled and measured concentrations in air, sediment, and biota indicates that our understanding of environmental fate is reasonable. VMS compounds are "fliers" that principally partition to the atmosphere, implying high LRTP, although they have low redeposition potential. They are degraded in air (half-lives 3-10 days) and, thus, have low overall persistence. In water, exposure can be limited by hydrolysis, volatilization, and partitioning to sediments (where degradation half-lives are likely to be high). In food webs, they are influenced by metabolism in biota, which tends to drive trophic dilution (i.e., trophic magnification factors are often but not always <1). Key remaining uncertainties include the following: (i) the strength and direction of the temperature dependence for K_OC ; (ii) the fate of atmospheric reaction products; and (iii) the magnitude of emissions to wastewater. Integr Environ Assess Manag 2022;18:599-621. © 2021 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Tissue-specific distribution and bioaccumulation of cyclic and linear siloxanes in South Korean crucian carp (carassius carassius)

The occurrence and distribution of cyclic and linear siloxanes were investigated in South Korean river water and sediment, with a special focus on crucian carp tissues, to evaluate the residual status and potential bioaccumulation of siloxanes. The total siloxanes median concentrations observed in this study were 1495 ng/L in river water, 39.2 ng/g-dry weight [dw] in sediment, and 41.7 ng/g-wet weight [ww] in crucian carp muscle. Cyclic siloxanes (D3-D6) were predominant in all matrices, and D5 (mean: > 81%) was more abundant in biota tissues than in river water (30%) and sediment (26%) samples. Specifically, positive correlations between D5 concentrations and crucian carp sizes (p < 0.01, Spearman) as well as the relatively high estimated biota-sediment accumulation factor value of D5 (D5: 2.31), suggest the high bioaccumulative property of D5 in biota. However, no bioaccumulation potentials were observed for D3, D4, D6, and L3-L17 in this field-scale study. The distributions of major linear siloxanes (L7-L14) in crucian carp gills (17%) and gonads (21%) were higher than in other tissues (brain, 9.6%; liver, 2.6%; muscle, 1.5%). Moreover, relatively high tissue/plasma ratios were observed for linear siloxanes (L7-L10: 1.79-2.12) compared to cyclic siloxanes (D4-D6: 0.829-1.18) (p < 0.01, Mann Whitney U test), which indicated the higher transportability of linear siloxanes to fish tissues than cyclic siloxanes.

Fugacity-Based Trophic Magnification Factors Characterize Bioaccumulation of Cyclic Methyl Siloxanes within an Urban Terrestrial Avian Food Web: Importance of Organism Body Temperature and Composition

Trophic magnification of cyclic volatile methyl siloxanes (cVMS) in a terrestrial food web was investigated by measuring concentrations of octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) and two reference chemicals within air and biota samples from an avian food web located in a mixed urban-agricultural landscape. Terrestrial trophic magnification factors derived from lipid normalized concentrations (TMF_Ls) for D5 and D6 were 0.94 (0.17 SE) and 1.1 (0.23 SE) and not statistically different from 1 (p > 0.05); however, the TMF_L of D4 was 0.62 (0.11 SE) and statistically less than 1 (p < 0.001). TMF_Ls of PCB-153 and p,p'-DDE were 5.6 (2.2 SE) and 6.1 (2.8 SE) and statistically greater than 1 (p < 0.001). TMF_Ls of cVMS in this terrestrial system were similar to those reported in aquatic systems. However, trophic magnification factors derived on a fugacity basis (TMF_Fs), which recognize differences in body temperature and lipid composition between organisms, were greater than corresponding TMF_Ls primarily because a temperature-induced thermodynamic biomagnification of hydrophobic chemicals occurs when endothermic organisms consume poikilothermic organisms. Therefore, we recommend that biomagnification studies of food webs including endothermic and poikilothermic organisms incorporate differences in body temperature and tissue composition to accurately characterize the biomagnification potential of chemicals.

Development of a New Passive Sampling Method for the Measurement of Atmospheric Linear and Cyclic Volatile Methyl Siloxanes

A new passive sampling method was developed and characterized to measure atmospheric volatile methyl siloxanes (VMS). The infrastructure of a commercial passive air sampler (PAS) was used along with XAD-2 resin as the adsorbent. Experimental sampling rates (SR) determined using collocated active and passive samplers ranged between 0.0363 (L5) and 0.0561 (D3) m³/day and agreed well with the theoretical ones. VMS uptake was highly linear for eight weeks. The precision of the method was very good (<10%). Compared to the other PASs used for VMS, the new method has several advantages (i.e., the sampler is much smaller, it has commercially available components, and the solvent requirement, equipment needed for extraction, and steps for sample preparation are minimal) while achieving similar or lower method detection limits. The developed method was applied to investigate the spatial distribution and possible sources of atmospheric VMS in the Izmir region. Field sampling covered 42 sites representing different source and land use areas. ΣVMS concentrations ranged between 41.4 and 981 ng/m³. The dominant VMS was D5 followed by D3 and D4. Spatial distributions indicated that the main VMS sources in the area were urban areas, wastewater treatment plants, and landfills where the VMS-containing products are used and disposed.

Characteristics, pollution patterns and risks of Perfluoroalkyl substances in drinking water sources of Taiwan

Perfluoroalkyl substances (PFASs) are found globally in the environment, but for Taiwan there is a lack of studies on PFAS occurrence, source apportionment, and health risks in drinking water sources. We collected surface water samples from the Baoshan Reservoir of Taiwan and used Positive Matrix Factorization to attribute PFAS contaminants to possible sources. The health index (HI) was used to evaluate the health risk, which was then compared to various international advisory level guidelines. PFOA and PFOS were found to be the most predominant compounds, with concentrations averaging 20.2 ng/L and 16.7 ng/L, respectively. The joint contribution of domestic and commercial waste totaled 61.2% as the predominant source of pollution, followed by urban activities as a secondary source contributing 38.8%. Using the USEPA reference dose, a health risk analysis of Baoshan Reservoir drinking water did not reflect a formal high health risk (HI < 1.0), however potential risks to human health may be present since the sum of PFOA and PFOS (130 ng/L) exceeded the USEPA Lifetime Health Advisory level (70 ng/L). This investigation provides information and reference points for further reviews of PFAS presence in public water supplies.

Disposal of products and materials containing per- and polyfluoroalkyl substances (PFAS): A cyclical problem

Per- and polyfluoroalkyl substances (PFAS), highly stable and persistent chemicals used in numerous industrial applications and consumer goods, pose an exceptionally difficult challenge for disposal. Three approaches are currently available for PFAS wastes: landfilling, wastewater treatment and incineration. Each disposal approach can return either the original PFAS or their degradation products back to the environment, illustrating that the PFAS problem is cyclical. Landfilling and wastewater treatment do not destroy PFAS and simply move PFAS loads between sites. Consumer products and various materials discarded in landfills leach PFAS over time, and landfill leachate is commonly sent to wastewater treatment plants. From wastewater treatment plants, PFAS are carried over to sludge and effluent. Sewage sludge can be landfilled, incinerated, or applied on agricultural fields, and PFAS from treated sludge (biosolids) can contaminate soil, water, and crops. Incineration of PFAS-containing wastes can emit harmful air pollutants, such as fluorinated greenhouse gases and products of incomplete combustion, and some PFAS may remain in the incinerator ash. Volatile PFAS are emitted into the air from landfills and wastewater treatment plants, and research is urgently needed on the potential presence of PFAS compounds in air emissions from commercially run incinerators. Monitoring of waste streams for PFAS, stopping PFAS discharges into water, soil and air and protecting the health of fence-line communities close to the waste disposal sites are essential to mitigate the impacts of PFAS pollution on human health.

Perfluoroalkyl substances in the Lingang hybrid constructed wetland, Tianjin, China: occurrence, distribution characteristics, and ecological risks

In this study, the occurrence, spatial distribution, sources, and ecological risks of perfluoroalkyl substances (PFASs) in the surface waters of the Lingang hybrid constructed wetland were systematically investigated. Twenty-three PFASs were analyzed from 7 representative sampling zones. The obtained results indicated that PFBA, PFPeA, PFHxA, PFHpA, PFOA, PFBS, PFOS, and HFPO-DA were frequently detected; and PFBA, PFOA, and PFOS were the dominant PFASs with the relative abundances in ranges of 26.91 to 52.26%, 11.79 to 28.79%, and 0 to 31.98%, respectively. The total concentrations of 8 PFASs (Σ₈PFASs) ranged from 25.9 to 56.6 ng/L, and the highest concentration was observed in subsurface flow wetland. Moreover, HFPO-DA with high toxicity was detected in wetlands for the first time. Based on the principal component analysis-multiple linear regression (PCA-MLR) analysis, three sources and their contributions were fluoropolymer processing aids (67.6%), fluororesin coatings and metal plating (17.9%), and food packaging materials and atmospheric precipitation (14.5%), respectively. According to the risk quotients (RQs), the ecological risk of 8 PFASs was low to the aquatic organisms.

Occurrence and Gas-Particle Partitioning of Organic UV-Filters in Urban Air

A retrospective analysis of a comprehensive series of high-volume air samples (n = 70) collected during 2010-2011 in Toronto (Canada) was performed. Seven UV compounds were analyzed by gas chromatography-tandem mass spectrometry (GC-MS/MS) with sum of concentrations (gas + particle phase) ranging from 80 to 2030 pg/m³. Homosalate (HMS) was the most prevalent organic UV-filter in air (47% of the total concentration), followed by 2-ethylhexyl salicylate (EHS, ∼29%), E- and Z-2-ethylhexyl 4-methoxycinnamate (EHMC, ∼17%). Ambient air (gas + particle phase) concentrations of organic UV-filters showed a strong seasonality, with peak levels during the summer. An analysis of Clausius-Clapeyron slopes indicated that much of the ambient burden of organic UV-filters are explained by volatilization from terrestrial and aquatic surfaces and supplemented with human activities and use of lotions and sunscreens, containing organic UV-filters, in addition to its use in plastics, textiles, paints, and pesticides. The results showed that organic UV-filters exist mainly in the gas phase with some exceptions, for instance, octocrylene (OCR), which was associated with both gas and particle phases, and avobenzone (AVB), which was predominantly in the particle phase. Lastly, this study revealed the need for basic physical chemical property data for organic UV-filters, including information on transformation rates and products, for better evaluating their environmental fate and effects.

Passive air sampling for semi-volatile organic chemicals

During passive air sampling, the amount of a chemical taken up in a sorbent from the air without the help of a pump is quantified and converted into an air concentration. In an equilibrium sampler, this conversion requires a thermodynamic parameter, the equilibrium sorption coefficient between gas-phase and sorbent. In a kinetic sampler, a time-averaged air concentration is obtained using a sampling rate, which is a kinetic parameter. Design requirements for kinetic and equilibrium sampling conflict with each other. The volatility of semi-volatile organic compounds (SVOCs) varies over five orders of magnitude, which implies that passive air samplers are inevitably kinetic samplers for less volatile SVOCs and equilibrium samplers for more volatile SVOCs. Therefore, most currently used passive sampler designs for SVOCs are a compromise that requires the consideration of both a thermodynamic and a kinetic parameter. Their quantitative interpretation depends on assumptions that are rarely fulfilled, and on input parameters, that are often only known with high uncertainty. Kinetic passive air sampling for SVOCs is also challenging because their typically very low atmospheric concentrations necessitate relatively high sampling rates that can only be achieved without the use of diffusive barriers. This in turn renders sampling rates dependent on wind conditions and therefore highly variable. Despite the overall high uncertainty arising from these challenges, passive air samplers for SVOCs have valuable roles to play in recording (i) spatial concentration variability at scales ranging from a few centimeters to tens of thousands of kilometers, (ii) long-term trends, (iii) air contamination in remote and inaccessible locations and (iv) indoor inhalation exposure. Going forward, thermal desorption of sorbents may lower the detection limits for some SVOCs to an extent that the use of diffusive barriers in the kinetic sampling of SVOCs becomes feasible, which is a prerequisite to decreasing the uncertainty of sampling rates. If the thermally stable sorbent additionally has a high sorptive capacity, it may be possible to design true kinetic samplers for most SVOCs. In the meantime, the passive air sampling community would benefit from being more transparent by rigorously quantifying and explicitly reporting uncertainty.

Cyclic volatile methylsiloxanes (cVMSs) in the air of the wastewater treatment plants in Dalian, China - Levels, emissions, and trends

Passive air samplers comprising sorbent-Tenax-TA thermal desorption tubes were applied for monitoring cyclic volatile methyl siloxanes (cVMSs) in the air above the aeration tanks of eight wastewater treatment plants (WWTPs, including five "open" and three "close" plants) in Dalian, China. The aim was to investigate the inputs of cVMSs from WWTPs to the air throughout a year (June 2016-July 2017). The ∑cVMS concentrations were averaged at 3.14 ± 6.84 μg·m^-³ with D5 as the dominant compound (contributing to 63.8% of the ∑cVMS concentration). The annual average concentrations of D4, D5, and D6 in the air of the "close" WWTPs were 5.33 ± 4.63, 13.4 ± 14.4, and 1.05 ± 1.47 μg·m^-³, and 1.31 ± 1.29, 1.57 ± 2.01, and 0.301 ± 0.340 μg·m^-³ in the air from the "open" WWTPs, respectively. For both the close and open aeration tanks, the concentration of ∑cVMSs was the highest in summer and the lowest in winter, showing a significant correlation with ambient temperature (linear regression; p < 0.01). A simplified Gaussian dispersion model and a single chamber model were introduced to estimate annual emissions (kg·yr^-1) of cVMSs from "open" and "close" WWTPs, ranging from 86.9 to 165 kg yr^-1 and from 203 to 278 kg yr^-1, respectively. Examining the relationship between the per capita emissions of cVMSs and average property prices, our results indicated that a greater amount of personal care products were used/discharged by people with relatively higher socioeconomic status.

Comparison of fluorotelomer alcohol emissions from wastewater treatment plants into atmospheric and aquatic environments

Recent studies have revealed that wastewater treatment plants (WWTPs) are an important source of fluorotelomer alcohols (FTOHs) in the environment. However, it remains unclear whether volatilization to the atmosphere or discharge with wastewater effluent into receiving water bodies is the dominant pathway through which FTOHs enter the environment; it also remains unclear how the relative importance of these two emission pathways varies among seasons and homologs. Here, we estimated the emissions of 6:2 and 8:2 FTOHs through these two pathways from a typical WWTP in Beijing, China, by measuring height-dependent air concentrations above the wastewater surface; we also measured wastewater concentrations among the four annual seasons. Our results showed that atmospheric emissions dominate total annual FTOH emissions, but are not dominant in every single season. Emission to the aquatic environment is dominant during seasons with less wind (i.e., summer and fall). While the abundance of 6:2 FTOH has increased in recent years, 8:2 FTOH remains the major FTOH homolog released into the environment in China. This study provides comprehensive information regarding FTOH emissions from WWTPs to the environment and practical guidance for future monitoring practices.

Tube-type passive sampling of cyclic volatile methyl siloxanes (cVMSs) and benzene series simultaneously in indoor air: uptake rate determination and field application

Cyclic volatile methyl siloxanes (cVMSs) and benzene series compounds have attracted increasing attention because they are associated with various adverse health effects. In this study, we developed and validated a novel passive air sampling method (PAS), using Tenax-TA as the sorbent, to measure the concentrations of cVMSs (D4, D5, and D6) and benzene series compounds simultaneously in indoor air. The uptake rates (R), which were calibrated side-by-side by an active air sampling method (Tenax-TA-AAS), ranged from 0.10 to 0.56 mL min-1 depending on chemicals, and the R of the TD tube with Tenax-TA was controlled by the sampler material-side and not the air-side. The passive sampling efficiency (PSE) of styrene and m,p-xylene was close to 1. Based on Pearson correlation analysis, a negative correlation was found between the molecular weight of compounds and their uptake rates. Furthermore, the calibrated Tenax-TA-PAS method was used to quantify cVMSs and benzene series compounds in a living room and an office environment in the urban area of Dalian, China. The concentrations of toluene were the highest in both the living room (10.4 μg m-3) and office (7.02 μg m-3) among the target compounds.

Size distribution, biological characteristics and emerging contaminants of aerosols emitted from an urban wastewater treatment plant

Air-liquid exchange process could spread pathogens and pharmaceutical emerging pollutants into the air as aerosol particles in an Urban wastewater treatment plants (UWTPs). These particles can later be transported to places where such pollution is unforeseen. In this study, measurements were conducted in the aeration area of a UWTP in northern Taiwan. According to this investigation, nanoparticles are major contributors to both the number and volume concentration of particles. Most fluorescent particles may be bacterial aggregates or fungal species. Moreover, nine common emerging contaminants were analyzed and found in both air and water samples. Among these contaminants, the most abundant chemicals in the air were erythromycin-H₂O (191.45 pg/m³) and methamphetamine (39.02 pg/m³). These results imply that UWTPs could be an emission source of emerging contaminants and bioaerosols, and the potential risk of inhalation exposure should be carefully evaluated.

Urban wastewater treatment plants as a potential source of ketamine and methamphetamine emissions to air

Urban wastewater treatment plants (WWTPs) can be an emission source of aerosol particles to the air and this process has the potential to spread emerging pollutants into the air, where the particles can be widely transported over long distances to areas where this pollution is unexpected. This study demonstrates aeration tanks in WWTPs as a potential source of ketamine, methamphetamine and other emerging contaminant emissions into the air. Ketamine and methamphetamine are frequently detected in high concentrations (maximum of 151.8-162.8 pg/m³) in gaseous and aerosol samples along with 24 other emerging contaminants. Through correlation analysis, the common occurrence of emerging contaminants in air is attributable to their high aqueous concentrations as well as their physicochemical properties. Two simple regression models are developed to provide a practical and convenient way to estimate the steady-state concentrations in air. The gas-phase emission model illustrates the relationship between the solubility, the pK_a and the aqueous concentration of compounds in the aeration basin and their gaseous concentrations in air (statistical strength of 74.1%; p value < 0.05), while the partition model establishes the ratio of a compound in the gas and particulate phases in air (statistical strength of 82.6%; p value < 0.05). The results provide a basis for assessing the risk of the inhalation exposure to airborne emerging contaminants; however, in-depth research addressing the impact of aerosols containing persistent pharmaceuticals on human health is still needed.

Validation of sampling techniques and SPE-UPLC/MS/MS for home and personal care chemicals in the Songhua Catchment, Northeast China

A method for the simultaneous determination of 18 home and personal care chemicals (HPCCs) in river water and wastewater was developed using solid-phase extraction and ultra-high-performance liquid chromatography with tandem mass spectrometry (SPE and UPLC/MS/MS). A series of tests were designed to find the potential background interference and loss of HPCCs during the sample preservation and pretreatment process. Our results suggested that a considerable amount of some target compounds were lost with increasing days of storage even at 4 °C. Accordingly, the samples were stored acidified and refrigerated, including during transportation, to reduce the losses. Experiments on filtration of water samples suggested that recoveries of many HPCCs were significantly affected by the filtration. It is therefore recommended to avoid filtration of water samples where possible. The internal standard corrected recoveries for the HPCCs ranged from 64.2 to 107.0%, except for benzisothiazolone which did not have an appropriate internal standard, in river water which was considered to be the most difficult matrix. The method detection limits for river water, influent and effluent samples were in the ranges of 0.17 to 42 ng/L, 13 to 5100 ng/L, and 0.50 to 200 ng/L, respectively. The validated method was applied for the determination of HPCCs in sewage water collected from a full-scale wastewater treatment plant (WWTP) in a typical urban city in Northeast China and from river water upstream and downstream of the WWTP. Linear alkylbenzene sulphonate, caffeine, methyl paraben, benzalkonium chloride, triclocarban, and triclosan were the major compounds detected in the river water and wastewater samples. Sampling variability for the WWTP (intra-day and inter-day) and cross-river was also determined with the purpose of designing future monitoring requirements. Small variations in these samples confirmed that composite samples and a single sampling event would be representative for future use.

Volatile methylsiloxanes in sewage treatment plants in Saitama, Japan: Mass distribution and emissions

Wastewater, aeration gas, dewatered sludge, and incineration ash and flue gas (from dewatered sludge) were collected from 9 sewage treatment plants (STPs) located in Saitama Prefecture, Japan, and analyzed for seven cyclic and linear volatile methylsiloxanes (VMSs) namely, D3, D4, D5, D6, L3, L4, and L5. The mass loadings and distribution of VMSs in STPs were estimated based on measured concentrations in liquid, solid, and gaseous samples, including incinerated dewatered sludge. Mass loading of ΣVMS varied widely from 21 kg y^-1 to 3740 kg y^-1, depending on the volume of wastewater treated in each STP. Mass % of ΣVMS distributed in aeration gas was 15% and that in activated sludge was 78%. Approximately 6.6% of ΣVMS remained in the final effluent. Overall, partitioning onto the activated sludge was the dominant removal mechanism for D4, D5, and D6, whereas volatilization was also an important removal mechanism for D4. Incineration was effective to degrade VMSs in dewatered sludge, with a reduction rate of >99%. Activated carbon treatment removed >99% of VMSs from the aeration gas. In Saitama Prefecture, total emission of ΣVMS via STPs was estimated at 434 kg y^-1, 86 kg y^-1, and 0.065 kg y^-1, to aquatic, atmospheric, and terrestrial environments, respectively, which accounted for 83%, 17%, and 0.01% of the total environmental emissions. Our results indicate that majority of VMSs in dewatered sludge can be removed by incineration and emission of VMSs through incineration ash landfill is negligible.

Long-range transport potential and atmospheric persistence of cyclic volatile methylsiloxanes based on global measurements

This study investigates persistence (P) and long-range transport potential (LRTP) of cyclic volatile methylsiloxanes (cVMS) based on the field measurements in the Northern Hemisphere. The field data consisted of published outdoor air concentrations of octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6) at urban, suburban, rural and remote locations excluding the point sources. Three major trends were observed. First, D4 and D6 concentrations were correlated with measured concentrations for D5 at the same times and locations in the majority of the datasets, reflecting the common sources and similar removal mechanism(s) for these compounds. Second, as the sampling sites changed from the source to remote locations along a south-to-north transect, average cVMS concentrations in air decreased in an exponential manner. The empirical characteristic travel distances (eCTD) extracted from these spatial patterns were smaller than model estimated values and differed in order among individual compounds (D4 ∼ D5 < D6). Finally, D5/D6 concentration ratios were also found to decrease exponentially along the same spatial gradient, contrary to model predictions of an increase based on current knowledge of mechanisms controlling atmospheric cVMS degradation. These findings suggest that there may be additional removal process(es) for airborne cVMS, currently not accounted for, that requires further elucidation.

Footprints in the sand - Assessing the seasonal trends of volatile methylsiloxanes and UV-filters

This study focused on the determination of seven volatile methylsiloxanes (VMSs) and eleven UV-filters (UVFs) in beach sand from the Oporto's region (Portugal). A QuEChERS methodology ("Quick, Easy, Cheap, Effective, Rugged, and Safe") was used to extract VMSs from the sand, which has never been employed before. To extract the UVFs, a solid-phase microextraction (SPME) was used. The analyses were performed by gas chromatography-mass spectrometry (GC-MS). Twenty-three beach sand samples were analysed, from two campaigns - summer/winter. VMSs were found in all the samples with concentrations ranging from 0.007 ± 0.001 to 17.8 ± 0.9 ng g^-1_dw, while UVFs in summer samples from 0.030 ± 0.001 to 373 ± 17 ng g^-1_dw. Cyclic VMSs and octocrylene (OC) were detected in higher concentrations. In general, higher levels were detected in summer than winter. Hazard quotients were determined and 3-(4'-methylbenzylidene) camphor (4-MBC), 2-ethylhexyl 4-methoxycinnamate (EMC) and benzophenone-3 (BP3) presented values >1, which may indicate that they may pose an ecotoxicological risk.

Urban sources of synthetic musk compounds to the environment

The occurrence and potential sources of synthetic musk compounds (SMCs) in the urban and surrounding environment were investigated. We analyzed air, soils and surface waters from a wide array of land-use types and urban densities including air from wastewater treatment plants (WWTPs), indoor, urban, rural, and remote Arctic sites; surface waters from urban and rural tributaries; and effluents of three WWTPs. In air, the median sum concentration of six selected polycyclic musks (Σ6PCMs) (i.e., galaxolide, tonalide, cashmeran, celestolide, phantolide, traseolide) were the highest from WWTP on-site > indoor > urban > WWTP off-site > rural. SMCs were not found in remote Arctic air indicating low potential for long-range atmospheric transport. SMCs were not found in soils, likely because of their high volatility and fast biodegradation rate. Galaxolide (HHCB) and tonalide (AHTN) were the two most abundant SMCs in air, tributaries and WWTP effluents. Σ6PCM concentrations in air taken along urban-rural transects and in tributary water were positively correlated with population density. In WWTP on-site air, trace levels of the toxic nitro-musks, namely musk xylene and musk ketone were detected and macrocyclic musks accounted for ∼10% of the total SMCs measured. In WWTP effluents, the concentrations of Σ6PCMs were proportional to the population served. We conclude that sources of SMCs to the outdoor urban environment and hence the surrounding region, originate from releases from indoor air, and temperature-dependent volatilization from WWTPs during treatment.

Occurrence and distribution of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) in natural forest soils: A nationwide study in China

Forests serve as the primary reservoir for organic carbon above ground. Previous studies have revealed that forest soils play key roles in the retention of persistent organic pollutants (POPs). In this study, the occurrence and distribution of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) were investigated in 54 surface soil samples from 28 natural forested mountain sites across China between 2012 and 2013. The detection frequency of PFOA (70%) was significantly higher than that of PFOS (4%). PFOA levels ranged from <0.9 to 9.0 pg·g^-1 dry weight (dw). Levels of PFOA and PFOS in forest soils were significantly lower than those in agricultural, urban and rural areas in China. Relatively high levels of PFOA were detected in Hubei Province (Jiugong Mountain, average: 3.4 pg·g^-1 dw) and Jiangxi Province (Wugong Mountain, average: 4.4 pg·g^-1 dw), where many domestic fluoropolymer manufacturers are located. PFOS was only detected in these two provinces (2.2 pg·g^-1 dw and 2.7 pg·g^-1 dw, respectively). From most of the surveyed mountains, the concentrations of PFOA increased with elevation. The lower temperature and greater precipitation probably made PFOA and its precursors available to transport and degrade more readily at higher altitude sites. A relatively higher level (1.9 ± 1.3 pg·g^-1 dw) of PFOA was found in the broadleaf evergreen forest area, mainly due to the high industrial emissions, plant retention, and precipitation rate in this area. Source were the dominant factor controlling the spatial distribution of PFOA in natural forest soils in China.

Air monitoring of new and legacy POPs in the Group of Latin America and Caribbean (GRULAC) region

A special initiative in the Global Atmospheric Passive Sampling (GAPS) Network was implemented to provide information on new and emerging persistent organic pollutants (POPs) in the Group of Latin America and Caribbean (GRULAC) region. Regional-scale atmospheric concentrations of the new and emerging POPs hexachlorobutadiene (HCBD), pentachloroanisole (PCA) and dicofol indicators (breakdown products) are reported for the first time. HCBD was detected in similar concentrations at all location types (<20-120 pg/m³). PCA had elevated concentrations at the urban site Concepción (Chile) of 49-222 pg/m³, with concentrations ranging <1-8.5 pg/m³ at the other sites in this study. Dicofol indicators were detected at the agricultural site of Sonora (Mexico) at concentrations ranging 30-117 pg/m³. Legacy POPs, including a range of organochlorine (OC) pesticides and polychlorinated biphenyls (PCBs), were also monitored to compare regional atmospheric concentrations over a decade of monitoring under the GAPS Network. γ-hexachlorocyclohexane (HCH) and the endosulfans significantly decreased (p < 0.05) from 2005 to 2015, suggesting regional levels are decreasing. However, there were no significant changes for the other legacy POPs monitored, likely a reflection of the persistency and slow decline of environmental levels of these POPs. For the more volatile OCs, atmospheric concentrations derived from polyurethane foam (PUF) (acting as an equilibrium sampler) and sorbent impregnated PUF (SIP) (acting as a linear phase sampler), were compared. The complimentary methods show a good agreement of within a factor of 2-3, and areas for future studies to improve this agreement are further discussed.

Determination of linear and cyclic volatile methyl siloxanes in biogas and biomethane by solid-phase microextraction and gas chromatography-mass spectrometry

A new method based on solid-phase microextraction (SPME) followed by gas chromatography-mass spectrometry (GC-MS) was developed for the analysis of seven linear (L2 - L5) and cyclic (D3 - D5) volatile methyl siloxanes (VMS) in biogas and biomethane, directly collected into Tedlar® bags (Tedlar SPME) from anaerobic digesters and wastewater treatment plants. The method was employed to monitor VMS content in biomethane produced by biogas upgrading with a pilot-plant membrane unit and provided adequate limits of quantification (< 0.05 mg m^-3) to detect trace siloxane impurities. Tedlar SPME was validated against a standard procedure based on indirect sampling of gas streams with sorbent tubes followed by solvent extraction and GC-MS. Method precision (RSD) on total and individual VMS concentrations was lower than 10%, while RSD values of the standard procedure were higher than 20%. Tedlar SPME suitably revealed high VMS levels, expressed as total volatile silicon (> 1 mg_Sim^-3), in wastewater biogas and provided a more efficient sampling of heavier VMS in comparison to the sorbent tubes method. At low values (< 0.1 mg_Sim^-3) typical of wood waste biogas and biomethane, no statistically significant differences were observed between the two methods. Overall, Tedlar SPME simplified the analytical procedure by reducing the procedural steps, avoiding the use of solvents and demonstrated its applicability for testing the quality of biomethane as advanced biofuel.

Organophosphorus esters (OPEs) in PM2.5 in urban and e-waste recycling regions in southern China: concentrations, sources, and emissions

Organophosphate esters (OPEs) are novel ubiquitous contaminants that are attracting growing concern, but their emissions into the environment are still poorly understood. In this study, 12 OPEs were measured in fine particulate matter (PM_2.5) at 20 industrial sites in an urban region and four e-waste recycling facilities in a rural region in southern China. There was no significant difference in the concentrations of ∑OPEs between the urban region (519-62,747 pg/m³, median = 2854 pg/m³) and the rural e-waste region (775-13,823 pg/m³, 3321 pg/m³). High OPE concentrations in urban PM_2.5 were generally associated with the electrical, electronic, plastic, and chemical industries. There were no significant correlations between most OPEs in these two regions, suggesting different emission mechanisms. The average emissions of ∑OPEs estimated using a simplified dispersion model were 73.0 kg/yr from the urban industrial point sources and 33.2 kg/yr from the e-waste recycling facilities. The estimated emission inventory from industrial activities in the whole city (3228-4452 kg/yr) was approximately 30-fold higher than that from the e-waste recycling (133 kg/yr) facilities because urban region has a much larger industrial scale. To the best of our knowledge, this is the first effort to model the emissions of OPEs from industrial and e-waste recycling activities to the atmosphere.

An evaluation on the intra-day dynamics, seasonal variations and removal of selected pharmaceuticals and personal care products from urban wastewater treatment plants

Pharmaceuticals and personal care products (PPCPs) in wastewater have become an emerging issue due to their negative effects on human health and aquatic ecosystems. Two full-scale municipal and industrial wastewater treatment plants (WWTPs) along the Songhua River were chosen to evaluate the intra-day dynamics, seasonal variations and removal of 12 selected PPCPs. Our results suggested that the selected PPCPs were frequently detected in the influent and effluent. Caffeine was the predominant compound in the influent; while the selected PPCPs was dominated by TCS in the effluent, suggesting the different fates of selected PPCPs in the WWTPs. The intra-day dynamics of PPCPs in the influent were evaluated, suggesting that the 12 PPCPs can be grouped into three categories because of their different use patterns. The analysis of seasonal changes of PPCPs concentrations in the WWTPs suggested that the concentrations of some PPCPs were influenced by the chemical usage, degradation and temperature. The removal efficiency for the PPCPs were very high with the values ranged from 70.0% to 99.7% for WWTP#1, and from 62.5% to 99.4% for WWTP#2. Significant seasonal variations of PPCPs removal efficiency were observed. Base on the mass loading of PPCPs in the two WWTPs, our results suggested that WWTP#1 in the urban core received much more PPCPs in comparison to WWTP#2 in the suburban regions, suggesting that influences of the service population.

Atmospheric Concentrations of New Persistent Organic Pollutants and Emerging Chemicals of Concern in the Group of Latin America and Caribbean (GRULAC) Region

A special initiative was run by the Global Atmospheric Passive Sampling (GAPS) Network to provide atmospheric data on a range of emerging chemicals of concern and candidate and new persistent organic pollutants in the Group of Latin America and Caribbean (GRULAC) region. Regional-scale data for a range of flame retardants (FRs) including polybrominated diphenyl ethers (PBDEs), organophosphate esters (OPEs), and a range of alternative FRs (novel FRs) are reported over 2 years of sampling with low detection frequencies of the novel FRs. Atmospheric concentrations of the OPEs were an order of magnitude higher than all other FRs, with similar profiles at all sites. Regional-scale background concentrations of the poly- and perfluoroalkyl substances (PFAS), including the neutral PFAS (n-PFAS) and perfluoroalkyl acids (PFAAs), and the volatile methyl siloxanes (VMS) are also reported. Ethyl perfluorooctane sulfonamide (EtFOSA) was detected at highly elevated concentrations in Brazil and Colombia, in line with the use of the pesticide sulfluramid in this region. Similar concentrations of the perfluoroalkyl sulfonates (PFAS) were detected throughout the GRULAC region regardless of location type, and the VMS concentrations in air increased with the population density of sampling locations. This is the first report of atmospheric concentrations of the PFAAs and VMS from this region.

Atmospheric concentrations and trends of poly- and perfluoroalkyl substances (PFAS) and volatile methyl siloxanes (VMS) over 7 years of sampling in the Global Atmospheric Passive Sampling (GAPS) network

Poly- and per-fluoroalkyl substances (PFAS) and volatile methyl siloxanes (VMS) were monitored at 21 sites in the Global Atmospheric Passive Sampling (GAPS) Network. Atmospheric concentrations previously reported from 2009 were compared to concentrations measured at these sites in 2013 and 2015, to assess trends over 7 years of monitoring. Concentrations of the fluorotelomer alcohols (FTOHs) and fluorinated sulfonamides and sulfonamidoethanols (FOSAs and FOSEs) were stable at these sites from 2009 to 2015 with no significant difference (p > 0.05) in concentrations. Elevated concentrations of all the neutral PFAS were detected at the urban sites as compared to the polar/background sites. The perfluorosulfonic acids (PFSAs), meanwhile, saw a significant increase (p < 0.001) in concentrations from 2009 to 2015. The perfluorocarboxylic acids (PFCAs) had elevated concentrations in 2015, however, the difference was not statistically significant (p > 0.05). Concentrations of the PFSAs and the PFCAs were similar at all location types, showing the global reach of these persistent compounds. Concentrations of the cyclic VMS (cVMS) were at least an order of magnitude higher than the linear VMS (lVMS) and the PFAS. Octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6) saw a weak significant increase in concentrations from 2009 to 2013 (p < 0.05), however, hexamethylcyclotrisiloxane (D3) had a strong significant decrease in concentrations from 2009 to 2015 (p < 0.01).

Can coastline plant species be used as biosamplers of emerging contaminants? - UV-filters and synthetic musks as case studies

Personal care products, an important class of emerging contaminants, have been frequently detected in different environmental matrices. Included in this category are synthetic musks compounds (SMCs) and UV-filters. Their occurrence in the coastal environment has been poorly studied. Therefore, this work aimed to verify whether five coastline plant species (Carpobrotus edulis, Cakile maritima, Medicago marina, Elymus farctus borealis-atlanticus and Euphorbia paralias) have the ability to accumulate 11 SMCs (cashmeran, celestolide, phantolide, galaxolide, tonalide, exaltolide, musk moskene, tibetene, ambrette, xylene and ketone) and 2 organic UVB filters (3-(4'-methylbenzylidene) camphor and octocrylene), functioning as biosamplers. To accomplish this task, a QuEChERS technique ("Quick, Easy, Cheap, Effective, Rugged, and Safe") was employed to extract the target compounds from the plant material collected in 15 beaches of Matosinhos and Vila Nova de Gaia (Portugal). The resulting extracts were analysed by gas chromatography-mass spectrometry. Limits of detection ranged from 0.02 ng g^-1 for celestolide and tonalide to 1.32 ng g^-1 for musk ambrette. The obtained recoveries were around 93% and relative standard deviation was generally less than 15%. SMCs were detected at levels ranging from 1.56 to 350 ng g^-1 dw and UV-filters from 2.9 to 264 ng g^-1 dw. Galaxolide and 3-(4'-methylbenzylidene) camphor were the synthetic musk and UV-filter detected in higher concentrations, respectively. Plants with higher water content accumulate better SMCs (hottentot-fig), while those with higher lipid content retain better the UV-filters (sea spurge).

Volatile Methylsiloxanes and Organophosphate Esters in the Eggs of European Starlings (Sturnus vulgaris) and Congeneric Gull Species from Locations across Canada

Volatile methylsiloxanes (VMSs) and organophosphate esters (OPEs) are two suites of chemicals that are of environmental concern as organic contaminants, but little is known about the exposure of wildlife to these contaminants, particularly in birds, in terrestrial and aquatic ecosystems. The present study investigates the spatial distributions of nine cyclic and linear VMSs and 17 OPEs in the eggs of European starlings (Sturnus vulgaris) and three congeneric gull species (i.e., herring gull (Larus argentatus), glaucous-winged gull (L. glaucescens), and California gull (L. californicus)) from nesting sites across Canada. ∑VMS concentrations for all bird eggs were dominated by decamethylcyclopentasiloxane (D5), dodecamethylcyclohexasiloxane (D6), and octamethylcyclotetrasiloxane (D4). With European starlings, birds breeding adjacent to landfill sites had eggs containing significantly greater ∑VMS concentrations (median: 178 ng g^-1 wet weight (ww)) compared with those from the urban industrial (20 ng g^-1 ww) and rural sites (1.3 ng g^-1 ww), indicating that the landfills are important sources of VMSs to Canadian terrestrial environments. In gull eggs, the median ∑VMS concentrations were up to 254 ng g^-1 ww and suggested greater detection frequencies and levels of VMSs in aquatic- versus terrestrial-feeding birds in Canada. In contrast, the detection frequency of OPEs in all European starling and gull eggs was lower than 16%. This suggested that low dietary exposure or rapid metabolism of accumulated OPEs occurs in aquatic feeding birds and may warrant further investigation for the elucidation of the reasons for these differences.

Volatile methylsiloxanes through wastewater treatment plants - A review of levels and implications

The use of siloxanes has been increasing due to physicochemical properties that are appropriate to be included in the formulations of a large variety of consumer products. This implies a considerable release of these chemicals into the environment, which caught the attention of the scientific community in view of some reports of potential hazardous effects. However, the studies related to the presence and partition of volatile methylsiloxanes (VMSs) in wastewater treatment plants (WWTPs) are still scarce. The aim of this review is to provide a comprehensive assessment of the current state of the knowledge concerning the presence of VMSs in WWTPs and also a discussion of the efficiency of the removal technologies available. Levels, fate and behaviour of VMSs in WWTPs were reviewed, covering not only the water and sludge lines during the treatment processes, but also in the surrounding air. Several approaches for the analysis of VMSs within the WWTPs have been developed to cope with the complexity of the mentioned matrices, which led to sometimes challenging protocols. Hence, an overview of methodologies normally used was also included in the present review. Regarding the wastewater samples, VMSs have been detected in influents in concentrations ranging from a few nanograms to a hundred micrograms per litre, in which linear VMSs were usually detected in lower levels than cyclic siloxanes. The levels of VMSs in effluents were lower than those found in influents, suggesting an effective removal from the water line. However, they are commonly accumulating in the sludge, instead of suffering degradation during the treatment process. Therefore, due to the volatile character of VMSs it can be expected that a fraction may be removed in WWTPs by volatilization, thus completing the mass balances to the whole treatment facilities.

Starch-based and multi-purpose nanofibrous membrane for high efficiency nanofiltration

The objective of the present work is to develop nanofibrous membranes from rice-flour based nanofibers containing PVA for high efficiency filtration.