Can on-site leachate treatment facilities effectively address the issue of perfluoroalkyl acids (PFAAs) in leachate?

In recent decades, the presence of perfluoroalkyl acids (PFAAs) in municipal solid waste leachate has emerged as a growing concern. Research has focused on PFAA release and occurrence characteristics in landfill and waste-to-energy leachate, highlighting their significant impact when released into wastewater treatment plants. Given the extremely high loading rate faced by current on-site leachate treatment plants (LTPs), the objective of this study is to assess whether the current "anaerobic/aerobic (A/O) + membrane bioreactor (MBR) + nanofiltration (NF) + reverse osmosis (RO)" configuration is effective in PFAAs removal. Concentrations of raw and treated leachate in 10 on-site LTPs with same treatment configuration and varying landfill ages were measured, and a comprehensive mass flow analysis of each treatment process was conducted. The results indicate that A/O treatment has limited capacity for PFAA removal, while NF and RO processes reached 77.44 % and 94.30 % removal rates of ∑PFAAs concentration, respectively. Short-chain PFAAs (> 80 % detected frequency) primarily influenced the distribution and variations of PFAAs in leachate and tend to disperse in the water phase. Correlation analysis revealed the current on-site LTPs exhibit a more efficient removal capacity for long-chain PFAAs.

Occurrence, behavior and fate of liquid crystal monomers in municipal wastewater

Liquid crystal monomers (LCMs), the essential substances used in the display screen of electronic devices, have been proposed as a class of emerging chemicals of concern. Despite their detection in various environmental matrices, little is known about the presence of LCMs in municipal sewage systems. This study aimed to investigate the occurrence, distribution, and fate of 64 LCMs released into the aqueous environment from a municipal wastewater treatment plant (WWTP) in Hong Kong, China. In total 14 LCMs were detected in WWTP samples. Specifically, the Σ14LCMs concentrations in crude influent, final effluent, and final sludge were found to be 16.8 ± 0.3 ng/L, 2.71 ± 0.05 ng/L, and 19.2 ± 1.0 ng/g dry weight, respectively. Among them, 10 fluorinated LCMs (F-LCMs) were determined to be present at concentrations of 8.90 ± 0.10 ng/L, 1.69 ± 0.05 ng/L, and 9.94 ± 1.00 ng/g dry weight, respectively. The predominant non-fluorinated LCMs (NF-LCMs) detected in all samples were 3OCB and EPhEMOB, while 2OdF3B was the dominant F-LCM. The overall removal rate of total LCMs was 83.8 ± 0.3 %, with 25.4 ± 4.8 % being removed by biodegradation and UV treatment. Compared to NF-LCMs, F-LCMs were more resistant to biodegradation. Despite the significant removal of LCMs through WWTP, the remaining LCMs in final effluent could result in an annual emission of 3.04 kg of total LCMs from the population of Hong Kong. This study provides the first evidence of LCMs contamination in municipal wastewater, possibly arising from routine electronic devices usage. Further investigation is needed to elucidate the potential impact of LCMs emission via WWTP effluent on the aquatic receiving ecosystem.

Mass flow of per- and polyfluoroalkyl substances (PFAS) in a Swedish municipal wastewater network and wastewater treatment plant

PER: and polyfluoroalkyl substances (PFAS) are ubiquitously distributed in wastewater, due to their numerous uses in industry and consumer products, but little is known of PFAS mass flows in municipal wastewater network systems and within wastewater treatment plants (WWTPs). This study assessed mass flows of 26 PFAS in a wastewater network and WWTP, to provide new insights into their sources, transport, and fate in different treatment steps. Wastewater and sludge samples were collected from pumping stations and the main WWTP in Uppsala, Sweden. PFAS composition profiles and mass flows were used to identify sources within the sewage network. Wastewater from one pumping station showed elevated concentrations of C₃-C₈ PFCA, likely caused by an industrial source, and two stations had elevated concentrations of 6:2 FTSA, probably originating from a nearby firefighter training facility. Within the WWTP, short-chain PFAS dominated in wastewater, whereas long-chain PFAS dominated in sludge. The ratio of perfluoroalkyl sulfonates (PFSA) and ethylperfluorooctanesulfonamidoacetic acid (EtFOSAA) to ∑₂₆PFAS decreased during the WWTP process, likely due to sorption to sludge, but also transformation (EtFOSAA). Overall, PFAS were not efficiently removed in the WWTP, with mean removal efficiency of 10 ± 68% for individual PFAS, resulting in discharge of 7000 mg d^-1 ∑₂₆PFAS into the recipient. This shows that conventional WWTPs are inefficient in removing PFAS from wastewater and sludge, so advanced treatment techniques are needed.

Quantifying environmental emissions of microplastics from urban rivers in Melbourne, Australia

This study aims to understand the amount and type of microplastics flowing into Port Phillip Bay from urban rivers around Melbourne. Water samples were collected from the Patterson, Werribee, Maribyrnong, and Yarra Rivers, which contribute 97 % to the total flow into Port Phillip Bay. On average, the rivers contained a mean of 9 ± 15 microplastics/L and ranged from 4 ± 3 microplastics/L (Patterson) to 22 ± 11 microplastics/L (Werribee). Of the eight polymers investigated, polyamide and polypropylene were the most frequently detected polymers. Using the mean concentration of each river, the flow of microplastics into Port Philip Bay was estimated to be 7.5 × 10⁶ microplastics per day and 3.7 × 10¹⁰ microplastics per year. To fully understand the fate and transport of microplastics into Port Phillip Bay, this study would be the foundation for a more in-depth investigation. Here, further samples will be collected at more points along the river and at the midpoint of each season.

Scaling of Chinese urban CO2 emissions and multiple dimensions of city size

Cities are both the primary cause of global climate change and the key to the mitigation agenda. China's unprecedented urbanization has paralleled a growth in energy demand and urban areas have emerged as the crux of CO₂ emissions reduction in China. There is a crucial need for policymakers to understand how CO₂ emissions scale with city size and adopt economies of scale (cost savings) for mitigation, particularly through a multidimensional lens of city size. This study reveals a set of scaling relations between urban scope 1 CO₂ emissions and five dimensions of city size in 340 Chinese cities, including population (POP), built-up area (BA), building height (BH), specific built-up area (SBA), and built-up volume (BV). The findings show that CO₂ emissions in Chinese cities scale linearly with POP and BA but sublinearly with BA, SBA, and BV, and more diverse regimes exist across various geographic zones, population hierarchies, administrative hierarchies, and governance contexts. The prevalent sublinear scaling regime between CO₂ emissions and SBA and BV demonstrates the potential importance of optimizing the vertical built-up landscapes for establishing a zero‑carbon society. Furthermore, the top 10 % and bottom 10 % performance of individual cities in emissions identified by the Scale-Adjusted Metropolitan Indicator (SAMI) (the smaller the better) highlights the imprints of the socioeconomic context (e.g., Low Carbon City Initiative) on the scaling of CO₂ emissions in Chinese cities, which is critical for developing decarbonization strategies. Our multidimensional analysis can assist in the local-tailored low-carbon development of Chinese cities.

Fate of progesterone and norgestrel in anaerobic/anoxic/oxic (A/A/O) process: Insights from biotransformation and mass flow

Progesterone (P4) and norgestrel (NGT) are two steroid progestogens that can pose adverse effects on aquatic organisms at ng/L levels. Despite increasing concern on their occurrence and removal in wastewater, their fate in the wastewater treatment process has not been well documented. This study identified the transformation products (TPs) of P4 and NGT in anaerobic/anoxic/oxic (A/A/O) process. Potential functional genes involved in biotransformation of P4 and NGT were explored. The elimination or formation behavior of P4, NGT and convinced TPs along various units of A/A/O process was revealed through the mass flow. Results showed that 12 and 13 TPs were identified in the P4 and NGT groups respectively, wherein 10 identical TPs and C-19 structures transformation pathways were observed in both groups. Six genes were found that may be involved in dehydrogenation and isomerization reactions in the pathways. Mass flow indicated that P4 and NGT were mainly eliminated in anaerobic and anoxic units, while convinced TPs mainly formed in anaerobic and anoxic units and were then eliminated in aerobic unit. Further, the ecological risks of the effluent should not be ignored as residual compounds including P4 or NGT and their TPs in the effluent still posed adverse effects on zebrafish transcript levels.

Global transportation of plastics and microplastics: A critical review of pathways and influences

The rapid development of modern society has largely increased the usage of plastic. Concerns arise when vast amount of plastic waste has been generated and disposed. The accumulated evidences suggest that plastic waste in all the natural matrixes has become a global contaminant, principles such as geological and biogeochemical cycles for plastic pollution have been proposed. Before a full estimation of plastic mass flow, however, the pathways, directions and influences involved in plastic transportation are warranted to be addressed. We made this critical review based on the quantitative and narrative approaches in plastic and microplastic sources, sinks and transportation at global and historical scales. We also addressed the roles of anthropogenic influences in the global transportation of microplastic. The hydrological, meteorological, oceanic and even biological progresses naturally influence the plastic cycle and flow directions within the Earth's Four Spheres. Anthropogenic activities participated in all sections of plastic transportation, from sources to sinks. The contribution from anthropogenic activities remains unknown but several point sources including primary emissions and landfills have been confirmed. The primary outcomes point out that plastic pollution is highly complex issues in terms of natural and human-driven dynamics. We suggested that more efforts were needed in seeking the key sections in plastic transportation between environmental compartments at a global scale.

Seasonal temperatures impact on the mass flows in the innovative integrated process of anaerobic membrane bioreactor and one-stage partial nitritation-anammox for the treatment of municipal wastewater

A pilot-scale anaerobic membrane bioreactor (AnMBR) integrated with a one-stage partial nitritation-anammox (PN/A) reactor was operated for the treatment of municipal wastewater (MWW) at seasonal temperatures of 15-25 °C. The removal efficiencies of COD and total nitrogen (TN) were always > 90% and > 75% respectively. The methanogenesis and PN/A were identified as the primary removal pathways of COD and TN, respectively, and were suppressed at low temperatures. With the temperature dropped from 25 °C to 20 °C to 15 °C, the methane-accounted COD decreased from 63.1% to 59.6% to 48.4%, and the PN/A-accounted TN decreased from 58.1% to 51.7% to 45.3%. The AnMBR and PN/A mutually complement each other in this combined process, as the AnMBR removed 8.5%-16.1% of TN by sludge entrainment and the PN/A reactor removed 2.6%-3.4% of COD by denitrification and aerobic oxidation. These results highlighted the strong feasibility of applying the AnMBR-PN/A process to the treatment of MWW in temperate climate.

Phloem anatomy and function as shaped by the cell wall

The partitioning of assimilated carbon is a complex process that involves the loading, long-distance transport, and subsequent unloading of carbohydrates from source to sink tissues. The network of plumbing that facilitates this coordinated process is the phloem tissue. Our understanding of the physiology of phloem transport has grown tremendously since the modern theory of mass flow was first put forward, aided by the concomitant progress of technology and experimental methodologies. Recent findings have put a renewed emphasis on the underlying anatomy of the phloem, and in particular the important role that cell walls play in enabling the high-pressure flow of photoassimilates through the sieve element. This review will briefly summarize the foundational work in phloem anatomy and highlight recent work exploring the physiology of phloem cell wall structure and mechanics.

Implementation of circular economy in the management of municipal solid waste in an Italian medium-sized city: A 30-years lasting history

The Circular Economy model is gaining attention as a key factor for boosting sustainable development. Reducing the consumption of raw materials, as well as increasing the amount of recycled waste, are the current challenges the municipal solid waste management system is called for. In this study, the evolution of the municipal waste management strategies in the city of Brescia was analysed, covering a period of 30 years. The results obtained by a) progressively extending the separate collection with street containers, b) building a Waste to Energy plant, and c) moving to a door to door collection system, were assessed via numerical indicators and mass balances. In order to highlight the complexity of the system, the waste flow, from collection to the achievement of the "end of waste" attribute, was followed. Separate collection with street containers came to a saturation percentage around 40%. The realization of the incineration plant eliminated the direct disposal of waste to landfills. With the introduction of the new collection system, the separately collected waste increased up to over 73%, the per capita amount of collected waste decreased from 685.3 kg/(in y) to 579.6 kg/(in y), and a significant reduction of recyclable materials in the unsorted waste was gained. In the paper, these achievements and their affecting factors are analysed. Moreover, criticalities in the calculation of material recovery indices due to the complexity of the system (72 transformation sites were identified) are discussed.

Fate of typical endocrine active compounds in full-scale wastewater treatment plants: Distribution, removal efficiency and potential risks

In this study, the distribution, removal efficiency, and potential risks of 9 typical endocrine active compounds (EACs) in two full-scale wastewater treatment plants (WWTPs) were investigated. The EAC concentrations ranged from 0.2 to 7394.2 ng/L in influents. The source of influents was a critical factor in determining the EAC levels. EACs were primarily removed in the secondary biological processing units, with removal efficiencies fluctuating from 13.7% to 98%. The biological treatment processes and operating parameters (i.e., HRT and SRT) influenced the EAC removal efficiency. Bisphenol A (BPA) and estriol were mainly removed by biodegradation, while antidepressants were primarily eliminated by sludge adsorption according to the distribution patterns and mass flow of EACs in WWTPs. Novosphingobium, Saprospiraceae, etc. were the core functional bacteria for EAC biodegradation. In addition, sertraline in effluents and dewatered sludge may pose medium environmental risks, while the other EACs pose low environmental risks.

Projecting impacts of climate change on metal mobilization at contaminated sites: Controls by the groundwater level

Heavy metal and metalloid contamination of topsoils from atmospheric deposition and release from landfills, agriculture, and industries is a widespread problem that is estimated to affect >50% of the EU's land surface. Influx of contaminants from soil to groundwater and their further downstream spread and impact on drinking water quality constitute a main exposure risk to humans. There is increasing concern that the present contaminant loading of groundwater and surface water systems may be altered, and potentially aggravated, by ongoing climate change, through large-scale impacts on recharge and groundwater levels. We investigated this issue by performing hydrogeological-geochemical model projections of changes in metal(loid) (As and Pb) mobilization in response to possible (climate-driven) future shifts in groundwater level and fluctuation amplitudes. We used observed initial conditions and boundary conditions for contaminated soils in the temperate climate zone. The results showed that relatively modest increases (0.2 m) in average levels of shallow groundwater systems, which may occur in Northern Europe within the coming two decades, can increase mass flows of metals through groundwater by a factor of 2-10. There is a similar risk of increased metal mobilization in regions subject to increased (seasonal or event-scale) amplitude of groundwater levels fluctuations. Neglecting groundwater level dynamics in predictive models can thus lead to considerable and systematic underestimation of metal mobilization and future changes. More generally, our results suggest that the key to quantifying impacts of climate change on metal mobilization is to understand how the contact between groundwater and the highly water-conducting and geochemically heterogeneous topsoil layers will change in the future.

Effect of organic loading rate on anaerobic digestion of pig manure: Methane production, mass flow, reactor scale and heating scenarios

The effect of organic loading rate (OLR) with total solid (TS) control (3%-8%) on the performance of anaerobic digestion of pig manure (PM) using completely stirred anaerobic reactor was investigated. Based on the lab data, how OLR affects mass flow, construction scale and heating requirement in a farm-scale biogas plant was calculated. And three scenarios of typical reactor-heating technology were comparatively analyzed. The optimal OLR was 1.89 g volatile solid (VS)/(L^.d) with methane yield of 438.38 mL/gVS in the lab condition. The lower OLR, the larger amount of water and energy consumption, lower methane production and larger amount of liquid digestate was observed. Thus, the reactor with low OLR was suitable in tropical regions with the main target of disposing PM and fertilizer production. High OLR has advantage in the investment, but owns risk of instable process for a long-term run. In our study, among the three heating supply scenarios, biogas boiler was the best option for the designed biogas plant with the given breeding scale under moderate OLR. Combined heat and power (CHP) has potential advantage for the biogas plant under high OLR.

Mass-flow-based removal and transformation potentials for TBBPA, HBCDs and PBDEs during wastewater treatment processes

At a sewage treatment plant, 27 polybrominated diphenyl ethers, 17 methoxylated brominated diphenyl ethers, nine hydroxylated brominated diphenyl ethers, three hexabromocyclododecane diastereomers, and tetrabromobisphenol A were monitored at five major treatment stages (the influent, primary settlement stage, biological reaction stage, secondary settlement stage, and the UV irradiation disinfection stage). Hexabromocyclododecanes were the dominant chemicals, contributing 40% of the total concentrations of the chemicals in the dissolved phase of the sewage. Brominated flame retardant mass flow in the wastewater was lower after than before the biological reaction stage, and more than 70% of the inflowing mass load was removed from the mainstream wastewater by becoming associated with the sludge. More than half of mass loads of parent brominated flame retardants in the wastewater were removed after the treatments, but up to 10% of the initial mass loads remained in the final effluent and was expected to be released into the aquatic environment. The hydroxylated and methoxylated brominated diphenyl ether concentrations decreased by <25%, much less than the polybrominated diphenyl ethers. It is possible that hydroxylated and methoxylated polybrominated diphenyl ethers formed through the transformation of polybrominated diphenyl ethers during the biological reactions of treatment processes.

The mass flow and proposed management of bisphenol A in selected Norwegian waste streams

Current initiatives for waste-handling in a circular economy favor prevention and recycling over incineration or landfilling. However, the impact of such a transition on environmental emissions of contaminants like bisphenol A (BPA) during waste-handling is not fully understood. To address this, a material flow analysis (MFA) was constructed for selected waste categories in Norway, for which the amount recycled is expected to increase in the future; glass, vehicle, electronic, plastic and combustible waste. Combined, 92tons/y of BPA are disposed of via these waste categories in Norway, with 98.5% associated with plastic and electronic waste. During the model year 2011, the MFA showed that BPA in these waste categories was destroyed through incineration (60%), exported for recycling into new products (35%), stored in landfills (4%) or released into the environment (1%). Landfilling led to the greatest environmental emissions (up to 13% of landfilled BPA), and incinerating the smallest (0.001% of incinerated BPA). From modelling different waste management scenarios, the most effective way to reduce BPA emissions are to incinerate BPA-containing waste and avoid landfilling it. A comparison of environmental and human BPA concentrations with CoZMoMAN exposure model estimations suggested that waste emissions are an insignificant regional source. Nevertheless, from monitoring studies, landfill emissions can be a substantial local source of BPA. Regarding the transition to a circular economy, it is clear that disposing of less BPA-containing waste and less landfilling would lead to lower environmental emissions, but several uncertainties remain regarding emissions of BPA during recycling, particularly for paper and plastics. Future research should focus on the fate of BPA, as well as BPA alternatives, in emerging reuse and recycling processes, as part of the transition to a circular economy.

More value from food waste: Lactic acid and biogas recovery

Anaerobic digestion (AD) is one of the traditional technologies for treating organic solid wastes, but its economic benefit is sometimes questioned. To increase the economic feasibility of the treatment process, the aim of this study was to recover not only biogas from food waste but lactic acid (LA) as well. At first, LA fermentation of food waste (FW) was conducted using an indigenous mixed culture. During the operation, temperature was gradually increased from 35 °C to 55 °C, with the highest performance attained at 50 °C. At 50 °C and hydraulic retention time (HRT) of 1.0 d, LA concentration in the broth was 40 kg LA/m(3), corresponding to a yield of 1.6 mol LA/mol hexoseadded. Pyrosequencing results showed that Lactobacillus (97.6% of the total number of sequences) was the predominant species performing LA fermentation of FW. The fermented broth was then centrifuged and LA was extracted from the supernatant by the combined process of nanofiltration and water-splitting electrodialysis. The process could recover highly purified LA by removing 85% of mineral ions such as Na(+), K(+), Mg(2+), and Ca(2+) and 90% of residual carbohydrates. Meanwhile, the solid residue remained after centrifugation was further fermented to biogas by AD. At HRT 40 d (organic loading rate of 7 kg COD/m(3)/d), the highest volumetric biogas production rate of 3.5 m(3)/m(3)/d was achieved with a CH4 yield of 0.25 m(3) CH4/kg COD. The mass flow showed that 47 kg of LA and 54 m(3) of biogas could be recovered by the developed process from 1 ton of FW with COD removal efficiency of 70%. These products have a higher economic value 60 USD/ton FW compared to that of conventional AD (27 USD/ton FW).

Mercury mass flow in iron and steel production process and its implications for mercury emission control

The iron and steel production process is one of the predominant anthropogenic sources of atmospheric mercury emissions worldwide. In this study, field tests were conducted to study mercury emission characteristics and mass flows at two iron and steel plants in China. It was found that low-sulfur flue gas from sintering machines could contribute up to 41% of the total atmospheric mercury emissions, and desulfurization devices could remarkably help reduce the emissions. Coal gas burning accounted for 17%-49% of the total mercury emissions, and therefore the mercury control of coal gas burning, specifically for the power plant burning coal gas to generate electricity, was significantly important. The emissions from limestone and dolomite production and electric furnaces can contribute 29.3% and 4.2% of the total mercury emissions from iron and steel production. More attention should be paid to mercury emissions from these two processes. Blast furnace dust accounted for 27%-36% of the total mercury output for the whole iron and steel production process. The recycling of blast furnace dust could greatly increase the atmospheric mercury emissions and should not be conducted. The mercury emission factors for the coke oven, sintering machine and blast furnace were 0.039-0.047gHg/ton steel, and for the electric furnace it was 0.021gHg/ton steel. The predominant emission species was oxidized mercury, accounting for 59%-73% of total mercury emissions to air.

Mass flow and energy balance plus economic analysis of a full-scale biogas plant in the rice-wine-pig system

This paper presents mass flow and energy balance as well as an economic analysis for a biogas plant in a rice-wine-pig system at a practical rather than laboratory scale. Results showed feeding amount was 65.30 t d(-1) (total solid matter (TSM) 1.3%) for the normal temperature continuous stirred tank reactor (CSTR), and 16.20 t d(-1) (TSM 8.4%) for the mesophilic CSTR. The digestion produced 80.50 t d(-1) of mass, with 76.41 t d(-1) flowing into rice fields and 4.49 t d(-1) into composting. Energy consumption of this plant fluctuated with seasons, and surplus energy was 823, 221 kWh/year. Thus, biogas plant was critical for material recycling and energy transformation of this agro-ecosystem. The economic analysis showed that the payback time of the plant was 10.9 years. It also revealed application of biogas as a conventional energy replacement would be attractive for a crop-wine-livestock ecosystem with anaerobic digestion of manure.

Perfluoroalkyl acids in municipal landfill leachates from China: Occurrence, fate during leachate treatment and potential impact on groundwater

Raw and treated landfill leachate samples were collected from 5 municipal landfill sites in China to measure the concentrations and contamination profile of perfluoroalkyl acids (PFAAs) in leachate during different steps of treatment. The total concentration of PFAAs (∑PFAAs) ranged from 7280 to 292,000 ng L(-1) in raw leachate and from 98.4 to 282,000 ng L(-1) in treated leachate. The dominant compounds measured were PFOA (mean contribution 28.8% and 36.8% in raw and treated leachate, respectively) and PFBS (26.1% and 40.8% in raw and treated leachate, respectively). A calculation of mass flows during the leachate treatment processes showed that the fate of individual PFAAs was substance and treatment-specific. The Chinese national leakage of ∑PFAAs to groundwater from landfill leachate was estimated to be 3110 kg year(-1), which is a significant environmental release that is potentially threatening the sustainable use of groundwater as a drinking water source.

Occurrence and trends in concentrations of perfluoroalkyl substances (PFASs) in surface waters of eastern China

Spatial distributions of perfluoroalkyl substances (PFASs) were investigated in surface waters in Shanghai, Jiangsu and Zhejiang Provinces of eastern China during 2011. A total of 39 samples of surface waters, including 29 rivers, 6 lakes and 4 reservoirs were collected. High performance liquid chromatography/negative electrospray ionization-tandem mass spectrometry (HPLC/(-)ESI-MS/MS) was used to identify and quantify PFASs. Concentrations of PFAS were greater in Shanghai than that in Zhejiang Province. Concentrations of the sum of PFASs (∑PFASs) in Shanghai and Kunshan ranged from 39 to 212 ng L(-1), while in Zhejiang Province, concentrations of ∑PFASs ranged from 0.68 to 146 ng L(-1). Perfluorooctanoic acid (PFOA) was the prevalent PFAS in Shanghai. In contrast, PFOA and perfluorohexanoic acid (PFHxA) were the prevalent PFASs in Zhejiang Province. Concentrations of perfluorooctane sulfonate (PFOS) ranged from <0.07 to 9.7 ng L(-1). Annual mass of ∑PFASs transported by rivers that flow into the East China Sea were calculated to be more than 4000 kg PFASs. Correlation analyses between concentrations of individual PFASs showed the correlation between PFHxA and PFOA was positive, while the correlation between PFHxA and perfluorooctane sulfonamide (FOSA) was negative in Shanghai, which indicated that PFHxA and PFOA have common sources. Principal component analysis (PCA) was employed to identify important components or factors that explain different compounds, and results showed that PFHxA and FOSA dominated factor loadings.

Oxygenated, nitrated, methyl and parent polycyclic aromatic hydrocarbons in rivers of Haihe River System, China: occurrence, possible formation, and source and fate in a water-shortage area

Substituted polycyclic aromatic hydrocarbons (SPAHs) occur ubiquitously in the whole global environment as a result of their persistence and widely-spread sources. Some SPAHs show higher toxicities and levels than the corresponding PAHs. Three types of most frequently existing SPAHs, oxygenated-PAHs (OPAHs), nitrated-PAHs (NPAHs), and methyl-PAHs (MPAHs), as well as the 16 priority PAHs were investigated in this study. The purpose was to identify the occurrence, possible transformation, and source and fate of these target compounds in a water shortage area of North China. We took a river system in the water-shortage area in China, the Haihe River System (HRS), as a typical case. The rivers are used for irrigating the farmland in the North of China, which probably introduce these pollutants to the farmland of this area. The MPAHs (0.02-0.40 μg/L in dissolved phase; 0.32-16.54 μg/g in particulate phase), OPAHs (0.06-0.19 μg/L; 0.41-17.98 μg/g), and PAHs (0.16-1.20 μg/L; 1.56-79.38 μg/g) were found in the water samples, but no NPAHs were detected. The concentrations of OPAHs were higher than that of the corresponding PAHs. Seasonal comparison results indicated that the OPAHs, such as anthraquinone and 2-methylanthraquinone, were possibly transformed from the PAHs, particularly at higher temperature. Wastewater treatment plant (WWTP) effluent was deemed to be the major source for the MPAHs (contributing 62.3% and 87.6% to the receiving river in the two seasons), PAHs (68.5% and 89.4%), and especially OPAHs (80.3% and 93.2%) in the rivers. Additionally, the majority of MPAHs (12.4 kg, 80.0% of the total input), OPAHs (16.2 kg, 83.5%), and PAHs (65.9 kg, 93.3%) in the studied months entered the farmland through irrigation.