Occurrence and Fate of Per- and Polyfluoroalkyl Substances (PFAS) in Atmosphere: Size-Dependent Gas-Particle Partitioning, Precipitation Scavenging, and Amplification.

The concerns about the fate of per- and polyfluoroalkyl substances (PFAS) in the atmosphere are continuously growing. In this study, size-fractionated particles, gas, and rainwater samples were simultaneously collected in Shijiazhuang, China, to investigate the multiphase distribution of PFAS in the atmosphere. Perfluoroalkyl carboxylic acids (PFCAs) dominated the total concentration of PFAS in atmospheric media. A strong positive relationship (0.79 < R2 < 0.99) was observed between the concentration of PFCAs and organic matter fraction (fOM) in different particle size fractions, while no such relationship for perfluoroalkyl sulfonic acids (PFSAs) and fOM, suggesting fOM may be an important factor influencing the size-dependent distribution of PFCAs. Temperature played a key role in the gas-particle partitioning of PFAS, while it did not significantly affect their particle-size-dependent distribution. The associative concentration fluctuation of particle and particle-bound PFAS during precipitation suggested that precipitation scavenging was an important mechanism for the removal of PFAS from the atmosphere. Furthermore, temporary increases in atmospheric PFAS concentrations were observed during the precipitation. Fugacity ratios of PFAS in rainwater and gas phase (log fR/fG ranged between 2.0 and 6.6) indicated a strong trend for PFAS to diffuse from the rainwater to the gas phase during the precipitation, which may explain that the concentration of PFAS in the gas phase continued to increase even at the end of the precipitation.

Source apportionment and specific-source-site risk of quinolone antibiotics for effluent-receiving urban rivers and groundwater in a city, China.

There is a large surface-groundwater exchange downstream of wastewater treatment plants (WWTPs), and antibiotics upstream may influence sites downstream of rivers. Thus, samples from 9 effluent-receiving urban rivers (ERURs) and 12 groundwater sites were collected in Shijiazhuang City in December 2020 and April 2021. For ERURs, 8 out of 13 target quinolone antibiotics (QNs) were detected, and the total concentration of QNs in December and April were 100.6-4,398 ng/L and 8.02-2,476 ng/L, respectively. For groundwater, all target QNs were detected, and the total QNs concentration was 1.09-23.03 ng/L for December and 4.54-170.3 ng/L for April. The distribution of QNs was dissimilar between ERURs and groundwater. Most QN concentrations were weakly correlated with land use types in the system. The results of a positive matrix factorization model (PMF) indicated four potential sources of QNs in both ERURs and groundwater, and WWTP effluents were the main source of QNs. From December to April, the contribution of WWTP effluents and agricultural emissions increased, while livestock activities decreased. Singular value decomposition (SVD) results showed that the spatial variation of most QNs was mainly contributed by sites downstream (7.09%-88.86%) of ERURs. Then, a new method that combined the results of SVD and PMF was developed for a specific-source-site risk quotient (SRQ), and the SRQ for QNs was at high level, especially for the sites downstream of WWTPs. Regarding temporal variation, the SRQ for WWTP effluents, aquaculture, and agricultural emissions increased. Therefore, in order to control the antibiotic pollution, more attention should be paid to WWTP effluents, aquaculture, and agricultural emission sources for the benefit of sites downstream of WWTPs.

High efficient electrochemical biosensor based on exonuclease-â ¢-assisted dual-recycling amplification for ultrasensitive detection of kanamycin.

A target-triggered and exonuclease-Ⅲ-assisted strand displacement, dual-recycling amplification reaction-based biosensor was developed for the rapid, ultrasensitive and accurate detection of kanamycin. The robust profiling platform was constructed using high conductive MXene/VS2 for the electrode surface modification and high active CeCu2O4 bimetallic nanoparticles as nanozyme to improve the sensitivity as well as the catalytic signal amplification of the biosensor. Using the dual supplementary recycling of primer DNA and hairpin DNA, the electrochemical platform could accurately detect kanamycin to as low as 0.6 pM from the range of 5 pM to 5 µM. By profiling five other antibiotics, this platform exhibited high specificity, enhanced repeatability and reproducibility. Based on these intrinsic characteristics and by utilizing milk and water samples, the as-designed biosensor offers a remarkable strategy for antibiotic detection due to its favorable analytical accuracy and reliability, thereby demonstrating potential application prospect for various antibiotic biosensing in food quality control, water contamination detection and biological safety analysis.

Spatial and temporal dynamic response of abundant and rare aerobic denitrifying bacteria to dissolved organic matter in natural water: A case study of Lake Baiyangdian, China.

Revealing the responses of abundant and rare aerobic denitrifying bacteria to dissolved organic matter (DOM) composition is essential for understanding the aquatic N cycle ecosystems. In this study, fluorescence region integration and high-throughput sequencing techniques were used to investigate the spatiotemporal characteristics and dynamic response of DOM and aerobic denitrifying bacteria. The DOM compositions were significantly different among the four seasons (P < 0.001) without spatial differences. Tryptophan-like substances (P2, 27.89-42.67%) and microbial metabolites (P4, 14.62-42.03%) were the dominant components, and DOM exhibited strong autogenous characteristics. Abundant (AT), moderate (MT), and rare taxa (RT) of aerobic denitrifying bacteria showed significant and spatiotemporal differences (P < 0.05). The responses of α-diversity and niche breadth of AT and RT to DOM differed. The DOM explanation proportion for aerobic denitrifying bacteria exhibited spatiotemporal differences based on redundancy analysis. Foliate-like substances (P3) had the highest interpretation rate of AT in spring and summer, while humic-like substances (P5) had the highest interpretation rate of RT in spring and winter. Network analysis showed that RT networks were more complex than AT networks. Pseudomonas was the main genus associated with DOM in AT on a temporal scale, and was more strongly correlated with tyrosine-like substances (P1), P2, and P5. Aeromonas was the main genus associated with DOM in AT on a spatial scale and was more strongly correlated with P1 and P5. Magnetospirillum was the main genus associated with DOM in RT on a spatiotemporal scale, which was more sensitive to P3 and P4. Special operational taxonomic units were transformed between AT and RT with seasonal changes, but not between the two regions. To summarize, our results revealed that bacteria with different abundances utilized DOM components differently, and provides new insight on the spatiotemporal response of DOM and aerobic denitrifying bacteria in aquatic ecosystems of biogeochemical significance.

Perfluoroalkyl acids (PFAAs) in urban surface water of Shijiazhuang, China: Occurrence, distribution, sources and ecological risks.

It is extremely important to analyze the contaminative behaviors of Perfluoroalkyl acids (PFAAs) due to their serious threats to urban environments which are closely related to humans. Current study aimed to explore the distribution, source apportionment and ecological risk assessment of PFAAs in surface water from Shijiazhuang, China. The concentrations of ∑PFAAs ranged from 19.5 to 125.9 ng/L in the investigation area. Perfluorobutanesulfonic acid (PFBS) and perfluoropentanoic acid (PFPeA) were the predominant contaminants (mean value: 14.3 ng/L and 16.6 ng/L, respectively). The distribution of PFAAs according to geospatial analysis and hierarchical clustering analysis (HCA) showed that higher levels of ∑PFAAs were detected in the southern surface water of Shijiazhuang and there was a stepwise decrease from the wet season to the dry season. Furthermore, based on source apportionment, the dominant potential sources were found to be wastewater treatment plant (WWTP) effluents and industrial discharge. The risk quotients (RQs) revealed low ecological risks of all PFAAs for aquatic organisms in Shijiazhuang surface water. Collectively, this study provided basic data for regulatory strategies for controlling PFAA pollutions in urban surface water.

Utilization of Hematite Particles for Economical Removal of o-xylene in a High-Temperature Gas-Solid Reactor.

To establish a novel approach for VOCs resource utilization, coupled o-xylene oxidation and hematite reduction was investigated in this study in a high-temperature gas-solid reactor in the temperature range 300-700 °C. As the o-xylene-containing inert gas (N2) stream traveled through the hematite particle bed, its reaction behavior was determined in programmed heating and constant temperature modes. Consequently, the effect of bed temperature, flow rate and o-xylene inlet concentration on both o-xylene removal performance and degree of hematite reduction was studied. The raw hematite and solid products were analyzed by TGA, XRF, XRD and SEM-EDS. The results showed that a temperature above 300 °C was required to completely eliminate o-xylene by hematite, and both o-xylene removal capacity and degree of hematite reduction at 5% breakthrough points enhanced on increasing the temperature and decreasing the flow rate. The increment in temperature from 300 °C to 700 °C led to a gradual reduction of Fe2O3 to Fe3O4, FeO and metallic iron. Thus, this study provides a novel, economic and promising technology for treating the VOC pollutants.

The key environmental influencing factors for the change of sediment bacterial community and antibiotics resistance genes in a long-term polluted lake, China.

In order to investigate the key environmental influencing factors for the change of sediment bacterial community structure (BCS) and antibiotics resistance genes (ARGs) in a long-term Quinolone antibiotics (QNs) and heavy metals (HMs) polluted lake, 16S rRNA MiSeq High-throughput Sequencing and Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) analysis methods were applied. Baiyangdian lake was subdivided into three habitats: (1) Habitat 1: greatly influenced by municipal wastewater; (2) Habitat 2: mainly impacted by aquaculture sewage and domestic wastewater; and (3) Habitat 3: with the least human activities. Through One-way ANOVA analysis, the results showed that most of QNs and HMs showed significant difference among three habitats. Both the highest richness and diversity indices of bacterial community appeared in Habitat 3. The abundance of Multidrug, Phenicol, Aminoglycoside, Teracycline, and Quinolone ARGs exhibited the highest values in Habitat 1, while the abundance of Macrolide-Lincosamide-Streptogramin (MLS), Rifamycinm, and Sulfonamide ARGs appeared the highest values in Habitat 2. The result of redundancy analysis exhibited that 68.8% and 93.8% of the change in BCS and ARGs can be explained by environmental factors, respectively. Pb (explained 37.5% (p = 0.002)) and Fleroxacin (FLE) (explained 51.3% (p = 0.026)) were the most important factors for the variation of BCS and ARGs, respectively. Therefore, the effects of antibiotics and HMs on BCS and ARGs should be simultaneously paid more attention. Furthermore, the ARGs results by PICRUSt were similar to the results by metagenomic shotgun sequencing analysis, thus the PICRUSt analysis method can be used in the future research.

Trophic transfer of antibiotics in the benthic-pelagic coupling foodweb in a macrophyte-dominated shallow lake: The importance of pelagic-benthic coupling strength and baseline organism.

In lake ecosystems, pelagic-benthic coupling strength (PBCS) is closely related to foodweb structure and pollutant transport. However, the trophic transfer of antibiotics in a benthic-pelagic coupling foodweb (BPCFW) and the manner in which PBCS influences the trophic magnification factor (TMFs) of antibiotics is still not well understood in the whole lake. Herein, the trophic transfer behavior of 12 quinolone antibiotics (QNs) in the BPCFW of Baiyangdian Lake were studied during the period of 2018-2019. It was revealed that 24 dominant species were contained in the BPCFW, and the trophic level was 0.42-2.94. Seven QNs were detected in organisms, the detection frequencies of ofloxacin (OFL), flumequine (FLU), norfloxacin (NOR), and enrofloxacin (ENR) were higher than other QNs. The ∑QN concentration in all species was 11.3-321 ng/g dw. The TMFs for ENR and NOR were trophic magnification, while for FLU/OFL it was trophic dilution. The PBCS showed spatial-temporal variation, with a range of 0.6977-0.7910. The TMFs of ENR, FLU, and OFL were significantly positively correlated with PBCS. Phytoplankton and macrophyte biomasses showed indirect impact on the TMFs of QNs by directly influencing the PBCS. Therefore, the PBCS was the direct influencing factor for the TMFs of chemicals.

Occurrence, migration and health risks of fluorescent whitening agents and phthalates in bottled water.

The occurrence and health risks of fluorescent whitening agents (FWAs) in bottled water were reported for the first time. FWA184 and FWA393 were the most frequently detected FWAs, with mean concentrations of 3.99-17.00 ng L-1. Phthalates (PAEs) such as dibutyl phthalate (DBP), di-iso-butyl phthalate (DiBP), and diethylhexyl phthalate (DEHP) were prevalent in bottled water, with mean levels of 40.89-716.66 ng L-1, and their concentrations in bottled water were much higher than those of FWAs. FWAs and PAEs in bottles and caps were extracted using organic solvent, and the correlation analysis showed that FWA393 and DEHP most likely originated from bottles, while bottle caps were the main sources of DBP and DiBP. The calculated risk quotients (RQs) of target substances and all age groups were considerably lower than the threshold of 0.1, indicating that consuming bottled water containing these plastic additives was unlikely to pose health risks for people of all ages. However, RQ values for underage people were several times higher than those for adults and hence cannot be neglected; therefore, special attention should be paid to understand the potential risks posed by the exposure to these plastic additives during early life stages, especially the infant stage.

Antibiotic resistance genes and mobile genetic elements in different rivers: The link with antibiotics, microbial communities, and human activities.

Rivers as a critical sink for antibiotic resistance genes (ARGs), and the distribution and spread of ARGs are related to environmental factors, human activities, and biotic factors (e.g. mobile genetic elements (MGEs)). However, the potential link among ARGs, microbial community, and MGEs in rivers under different antibiotic concentration and human activities remains unclear. In this study, 2 urban rivers (URs), 1 rural-urban river (RUR), and 2 rural rivers (RRs) were investigated to identify the spatial-temporal variation and driving force of ARGs. The total concentration of quinolones (QNs) was 160.1-2151 ng·g-1 in URs, 23.34-1188 ng·g-1 in RUR, and 16.39-85.98 ng·g-1 in RRs. Total population (TP), gross domestic production (GDP), sewage, industrial enterprise (IE), and IEGDP appeared significantly spatial difference in URs, RUR, and RRs. In terms of ARGs, 145-161 subtypes were detected in URs, 59-61 subtypes in RURs, and 46-79 subtypes in RRs. For MGEs, 55-60 MGEs subtypes were detected in URs, 29-30 subtypes in RUR, and 29-35 subtypes in RRs. Significantly positive correlation between MGEs and ARGs were found in these rivers. More ARGs subtypes were related to MGEs in URs than those in RUR and RRs. Overall, MGEs and QNs showed significantly direct positive impact on the abundance of ARGs in all rivers, while microbial community was significantly positive impact on the ARGs abundance in URs and RUR. The ARGs abundance in URs/RUR were directly positive influenced by microbial community/MGEs/socioeconomic elements (SEs)/QNs, while those in RRs were directly positive influenced by QNs/MGEs and indirectly positive impacted by SEs. Most QNs resistance risk showed significantly positive correlation with the abundance of ARGs types. Therefore, not only need to consider the concentration of antibiotics, but also should pay more attention to SEs and MGEs in antibiotics risk management and control.

[Spectral Characteristics and Sources of Dissolved Organic Matter in Inflow Rivers of Baiyangdian Lake Water in Summer Flood Season].

DOM is the largest reservoir of organic carbon in the world, and it plays a crucial role in the biogeochemical cycles of natural water bodies. A river is a transition area connecting source water and receiving water that controls the DOM exchange between them. Therefore, in this study, ultraviolet visible spectroscopy (UV-vis) and three-dimensional fluorescence spectroscopy (EEMs) combined with parallel factor analysis (PARAFAC) were used to analyze the spectral characteristics and sources of dissolved organic matter in the Fuhe River, Xiaobai River, Baigouyin River, and Puhe River of Baiyangdian. The results showed that a245 and a355 in the Fuhe River and Xiaobai River were significantly higher than those in the Baigouyin River and Puhe River. E2/E3 showed that the DOM relative molecular mass of the inflow river water body was Puhe River > Baigouyin River > Fuhe River > Xiaobai River. Three components, tyrosine-like (C1), terrigenous humus (C2), and tryptophan-like (C3), were determined using three-dimensional fluorescence through PARAFAC. There was no difference among the fluorescence components (P>0.05), but there were differences among the C2 and C3 components (P<0.05). The proportion of easily degradable protein-like components (C1+C3) was higher than that of humus-like components (C2). The autogeny index BIX was greater than 1, and the humification index HIX was less than 4, indicating that the autogeny characteristics of the river bodies were obvious, and the humification degree was weak. The FI index was the highest (1.96±0.25), and the HIX index was the lowest (0.46±0.08), and the self-generated source characteristics gradually strengthened along the direction of the river entering the lake, indicating that the water body of the Fuhe River showed higher endogenous and autogenic characteristics. Based on the correlation analysis of fluorescence components and characteristic parameters of DOM, the correlations between the Fuhe River and Xiaobaihe River and between the Baigouyin River and Puhe River bodies were similar. The correlation between fluorescence components of DOM and water quality parameters of each lake was significantly different, and it was strongly correlated with nitrogen and phosphorus in water. According to multiple linear regression analysis, there was no significant difference among C1 components, but there was a significant difference between C2 and C3 components. In summary, the carbon cycle process of Baiyangdian Lake was further understood through the study on the DOM spectral characteristics and sources of the inflow river waters in the summer flood season.

[Spatial and Temporal Distribution of Antibiotic Resistance Genes in Different River Sediments in Typical Cities: A Case Study of Shijiazhuang].

Rivers are important reservoirs of antibiotic resistance genes (ARGs). However, most current studies have focused on the temporal and spatial distribution, and data on the differences in the species and abundance of ARGs between urban and rural rivers is still lacking for certain areas. In view of this, two rural rivers and three urban rivers were selected in Shijiazhuang City. In both December 2020 and April 2021, sediments were collected at 15 sampling sites. Metagenomic sequencing technology was used to compare the differences in temporal-spatial variation for ARGs in sediments. The results showed that:① 162 and 79 ARGs were detected in urban (4 776 ±4 452) and rural rivers (1 043 ±632), respectively. The abundance and species of ARGs in urban rivers were higher than those in rural rivers. ② The relative abundances of sulfonamide (SAs,27 %), aminoglycoside (AGs,26 %), and multidrug (MDs,15 %) ARGs had the highest abundance in urban rivers, whereas the relative abundance of MDs ARGs was highest in rural rivers (65 %). On the whole, the complexity of ARGs in urban rivers was higher than that in rural rivers. ③ There was a significant positive correlation between SAs, AGs, MDs, tetracycline, phenicol, macrolides-lincosamids-streptogramins (MLS), ß-lactams, and diaminopyrimidine ARGs in urban rivers (P < 0.01); however, there was a significant negative correlation between glycopeptide ARGs and all types of ARGs (P < 0.05 and P < 0.01). There was a significant positive correlation between MDs and SAs ARGs in rural rivers (P < 0.05), but there was a significant negative correlation between amino aminocoumarin, peptide, rifamycin, and fosfomycin ARGs (P < 0.05 and P < 0.01). ④ For the temporal variation in urban rivers, 162 ARGs (4 776 ±4 452) and 148 ARGs (5 673 ±5 626) were detected in December and April, respectively. For the temporal variation in rural rivers, 79 species (1 043 ±632) and 46 species (467 ±183) were detected in December and April, respectively. ⑤ RDA analysis results showed that the spatial-temporal distributions of ARGs in urban and rural rivers were different. Correlation analysis showed that the ARGs in urban rivers were significantly correlated with the number of industrial enterprises, whereas the ARGs in rural rivers were significantly correlated with the output value of animal husbandry. In general, this study identified the main influencing factors for ARGs in different rivers and provided data support for ARGs risk management in different rivers.

[Dynamic Response of Aerobic Denitrification Bacteria to Water Quality in Baiyangdian Lake Under Different Hydrological Scenarios].

In order to explore the evolution law and driving mechanism of aerobic denitrification bacteria in Baiyangdian Lake under different hydrological scenarios, based on water quality survey and high-throughput sequencing technology, this study conducted a water quality factor analysis and aerobic denitrification bacteria α-diversity analysis, species composition, and network analysis. The results showed that the water body of Baiyangdian Lake was weakly alkaline, with the highest T and the lowest DO in the rainy season and the lowest T and the highest DO in the freezing season. There were significant differences between NH4+-N, NO2--N, NO3--N, TN, permanganate index, Fe, and Mn in Baiyangdian water under different hydrological scenarios (P < 0.01), and there was no significant difference in TP under different hydrological scenarios (P > 0.05). The largest category in water bodies under different hydrological scenarios was Proteobacteria, and the genera with a higher relative abundance were Magnetospirillum, Aeromonas, Pseudomonas, Azospirillum, and Bradyrhizobium. In addition, within the aerobic denitrifying bacteria community, there were significant differences in α-diversity (P < 0.001), with the highest abundance of microbial communities occurring during the freezing period, and the highest diversity and evenness of microbial communities during the dry and freezing periods. According to the RDA and Mantel analyses, the water quality driving factors of flora were different under different hydrological scenarios. The water quality driving factors of flora in the dry season were pH, NO3--N, NO2--N, and permanganate index; the driving factors of flora in the rainy season were pH, T, DO, NO2--N, and TP; the driving factors of flora in the normal season were NO2--N, Fe, and permanganate index; and the driving factors of flora in the freezing season were NO3--N and NONO2--N. Network analysis showed that there were temporal differences in species related to water quality driving factors. The genera related to water quality driving factors during the dry season were Magnetospirillum, Aeromonas, and Azoarcus, whereas the genera related to the rainy season were Magnetospirillum, Pseudomonas, and Aeromonas. The genera related to the normal season were Magnetospirillum, Pseudomonas, and Limnohabitans, and the genera related to the freezing period were Magnetospirillum, Azoarcus, and Pseudomonas. The relationship between key water quality factors (mainly T, DO, NO3--N, and permanganate index) and aerobic denitrification flora in different hydrological scenarios was gradually changing with time. In conclusion, the study on the evolution characteristics of aerobic denitrification bacteria in Baiyangdian Lake under different hydrological scenarios and the driving mechanism of environmental factors could provide a basis for understanding the evolution mechanism of aerobic denitrification bacteria in the natural environment.

Pollution characteristics, ecological and health risks of herbicides in a drinking water source and its inflowing rivers in North China.

This study measured the pollution characteristics and ecological and health risks of 19 herbicides found in drinking water sources and their inflowing rivers. The targeted herbicides were prevalent in the study area, but most concentrations were well below 10 ng L-1. Acetochlor and atrazine were the dominant herbicides, although their levels were much lower than previously reported. Total herbicide residual levels were greater in April than in December and increased from upstream to downstream, resulting in the highest pollution levels found in the reservoirs, likely due to herbicides delivered from upstream and dense agricultural planting in the surrounding areas. Only atrazine and ametryn presented moderate ecological risks, while the summed risk quotients (ΣRQs) of each sample were >0.1, indicated that the total herbicide levels represented a moderate risk in all samples. For the human health risks, the risk quotients (RQ) of all target herbicides, the total RQs of each sample, and estimated life-stage RQs were far smaller than the 0.2 threshold, indicating the absence of human health risks when the water was consumed at any stage of life. However, early life stages exhibited 3-6 times higher RQ values than adulthood and should not be overlooked. And crucially, the synergistic or antagonistic effects of mixed herbicides are not well understood, and further research is needed to understand the impact of these herbicides on the ecosystem and human health, particularly possible affects in early life stages, such as infants and children.

Bipedal DNAzyme walker triggered dual-amplification electrochemical platform for ultrasensitive ratiometric biosensing of microRNA-21.

Circulating microRNAs (miRNAs) can be regarded as reliable noninvasive biomarkers in body fluids for the early diagnosis, prognosis, and monitoring of cancers. By combining target triggered bipedal DNAzyme walker cleavage cycling amplification and planar intercalated methylene blue (MB) molecules amplification, a versatile ratiometric electrochemical biosensing system is constructed for miRNAs detection. Using the microRNA-21 (miRNA-21) as a triggered model target from breast cancer cells (MCF-7) and cervical cancer cells (HeLa), the sensitivity and feasibility of the ratiometric biosensing strategy were verified on the basis of decreased streptavidin-conjugated cupric sulfide@platinum (CuS@Pt-SA) nanozyme signal with cleaved Zn2+-dependent DNAzyme walkers as well as enhanced duplex section of MB signal, which were assisted by the modification of high electronic conductivity and specific surface area of metallic WSe2 nanoflowers on the electrode. Hence, the introduced sensing strategy of higher cleavage activity of the bipedal DNAzyme walker cyclic amplification resulted into the remarkable sensitive measurement which had a detection limit of 0.16 fM from 1 fM to 1 nM for miRNA-21. Benefiting from the precise design of the capture Hairpin DNA, this proposed method showed excellent specificity to distinguish miRNA-21 from other miRNAs sequences, in addition to possessing good stability and reproducibility. Thus, this versatility platform can be utilized to sense various miRNAs biomarkers by simple of the redesigning the capture Hairpin DNA, hence presents a great promise in clinical application towards early cancer diagnosis, biological analysis and prognosis.

Distribution of per- and poly-fluoroalkyl substances and their precursors in human blood.

Many studies have examined per- and poly-fluoroalkyl substances (PFASs) in human blood. However, the distribution of PFASs in human blood remains not well known, especially for perfluorooctane sulfonate (PFOS) precursors. In this study, human blood samples (n = 162) were collected from general Chinese population, and then the isomer-specific partitioning of PFASs between human plasma and red blood cells (RBCs) were investigated. Perfluorooctanoate (PFOA) and PFOS were consistently the predominant PFASs in both human plasma and RBCs. In human blood, among C4-C7 perfluoroalkyl carboxylates (PFCAs), the calculated mean mass fraction in plasma (Fp) values increased from 0.76 to 0.82 with the increasing chain length. C7-C13 PFCAs exhibited a trend of gradually decreasing mean Fp with chain length. Among PFAS precursors, 6:2 fluorotelomer phosphate diester had the highest mean Fp value (0.87 ± 0.11). Calculated Fp values of N-methyl perfluorooctanesulfonamide (N-MeFOSA) and N-ethyl perfluorooctanesulfonamide (N-EtFOSA) were 0.66 ± 0.13 and 0.70 ± 0.12, respectively. Individual branched isomers consistently had greater Fp values than their corresponding linear isomers for PFOA, PFHxS, and perfluoroctane sulfonamide. To our knowledge, this study first reports the distribution of N-MeFOSA and N-EtFOSA in human blood, contributing to the better understanding of the occurrence and fate of PFASs in humans.

[Pollution Characteristics and Health Risk Assessment of Per- and Polyfluoroalkyl Substances and Emerging Alternatives in Road Dust, Shijiazhuang].

Per- and polyfluoroalkyl substances (PFASs, n=22), including emerging alternatives, in dust samples were analyzed using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) to study their pollution characteristics. These samples were collected from main and minor roads in Shijiazhuang. Some of the roads were located near sewage treatment plants and fire stations. The results showed that PFASs were ubiquitous in the road dust of Shijiazhuang; in particular, hexafluoropropylene oxide dimer acid (HFPO-DA), an alternative, was measured for the first time in China. The total concentrations of PFASs ranged from 2.62 to 137.65 ng·g-1. Perfluorooctanoic acid (PFOA) was the dominant PFAS, followed by perfluorobutanoic acid (PFBA), HFPO-DA, and perfluorooctane sulfonic acid (PFOS). The highest and lowest levels of PFASs were observed in the northwest and southeast regions of Shijiazhuang, respectively. The compositions of PFASs were obviously different in road dust near sewage treatment plants and fire stations, especially for the types of emerging alternatives. Health risk assessment indicated that road dust intake had a low risk of human exposure to PFASs and emerging alternatives. Among the three routes (ingestion intake, inhalation intake, and dermal contact), ingestion intake was the main route for PFASs and emerging alternatives in road dust to enter the human body. Under the same exposure route, the exposure dose of children was higher than that of adults.

Response of dissolved organic matter to thermal stratification and environmental indication: The case of Gangnan Reservoir.

Dissolved Organic Matter (DOM), an important part of the carbon cycle in reservoir ecosystems, has a great impact on aquatic environment to recognize the conversion process of different media DOM. The distribution, spectral characteristics, and sources of DOM in Gangnan Reservoir during thermal stratification were analyzed using ultraviolet-visible absorption spectroscopy and excitation-emission matrix spectroscopy. Three humic-like components (C2, C3, and C4) and two protein-like components (C1 and C5) were identified. The proportions of the humic-like components increased with the progression of thermal stratification (C2 and C3 were dominant), whereas the protein-like components decreased in proportion, and the trend in the interstitial water was constant (C3 and C4 were dominant). The proportion of the humic-like components in the sediments was highest during the stationary period of thermal stratification (C2 and C3 were dominant). C2 and C3 were significantly correlated in the water body and interstitial water (P < 0.001), while C1 and C5 were correlated in the sediment (P < 0.05). In the water body, C2 and C3 were negatively correlated during the formative period of thermal stratification (slope = -1.85; R2 = 0.52), strongly positively correlated during the stationary period (slope = 0.76; R2 = 0.94), and positively correlated during the weakening period of thermal stratification (slope = 0.46; R2 = 0.30). With the progression of thermal stratification, the relative contribution of endogenous substances decreased gradually, whereas the humification degree increased in the water body and interstitial water. The protein-like components and key physicochemical factors (Fe, Mn, TN, TP, and CODMn) were significantly correlated during the formative period (P < 0.05), and humic-like components and key physicochemical factors (NO2--N and TN) were significantly correlated during the stationary and weakening periods (P < 0.05). C1, C4, and C5 indicated NO3--N during the formative period; C2 and C3 indicated NO3--N during the stationary period; and C2 and C4 indicated NO3--N during the weakening period in the water body. These findings enhance the understanding the mutual transformation processes of DOM in reservoir ecosystems and could guide water quality management.

Hexabromocyclododecanes in surface soil-maize system around Baiyangdian Lake in North China: Distribution, enantiomer-specific accumulation, transport, temporal trend and dietary risk.

This study investigated the occurrence of hexabromocyclododecanes (HBCDs) in soil-maize system around Baiyangdian Lake. The total concentration of ΣHBCDs was in the order of industrial area > residential area > marginal area > Fuhe River estuary in soil. γ-HBCD was predominated in soils, roots and stems, while α-HBCD was the main diastereoisomer in leaves and kernels. Concentration of ΣHBCDs and three diastereoisomer concentrations in soils were significantly reduced and remained low level from 2018 to 2019. Selectivity enrichment of (+)α- and (-)γ-HBCD was found in soils, roots, stems and leaves, whereas only (+)ß-HBCD dominated in stems. Most of the total root bioaccumulation factors (ΣRCFs) were less than 1.0, but no significant correlation was showed between translocation factors (TFs) and log Kow. RCFs and TFs of enantiomers suggested (-)ß- and (-)γ-HBCD were easily translocated from soil to roots, while (+)α-, (-)ß- and (-)γ-HBCD tended to translocate from stems to leaves. Estimated daily intake (EDI) and of ΣHBCDs, diastereoisomers and enantiomers were all lower than the threshold value, while the Calculated margins of exposure (MOE) were well above the threshold value, which demonstrate the safe consumption of Maize around Baiyangdian Lake.

Implication of ferroptosis in hepatic toxicity upon single or combined exposure to polystyrene microplastics and cadmium.

Microplastics (MPs) are a newly emerging type of pollutants. To date, MPs have been found in the atmosphere, soil, water, and even in human samples, posing a non-negligible threat to humans. Furthermore, multiple heavy metals have been found to co-exist with MPs or be absorbed by MPs. This leads to a widespread concern about their combined toxicity, which is currently elusive. Herein, we investigated the single or combined toxic effects of polystyrene MPs (PS-MPs) and cadmium chloride (CdCl2) on the liver and hepatocytes. After co-incubation, cadmium (Cd) can be absorbed by PS-MPs, resulting in physiochemical alterations of PS-MPs. In vivo and in vitro experiments revealed that PS-MPs solely or together with CdCl2 induced ferroptosis in hepatocytes, a newly defined programmed cell death characterized by lipid oxidation and iron accumulation. PS-MPs exerted more ferroptotic effect on hepatocytes than CdCl2, and combined exposure to PS-MPs and CdCl2 enhanced their ferroptotic effect, mainly by stimulating reactive oxygen species (ROS) production and inhibiting antioxidant activity. Upon single or combined exposure to PS-MPs and CdCl2, the induction of ferroptosis in hepatocytes can be inhibited by N-acetyl-cysteine (NAC, an ROS scavenger), deferoxamine (DFO, an iron chelator), and particularly ferrostatin-1 (Fer-1, a specific ferroptosis inhibitor). Fer-1 efficiently rescued the cell viability of hepatocytes upon exposure to PS-MPs and CdCl2 through enhancing the antioxidant system via upregulating GPX4 and SLC7A11. These findings would contribute to an in-depth understanding of the single and combined toxicity of microplastics and cadmium.