Efficient photocatalytic degradation of perfluorooctanoic acid by bismuth nanoparticle modified titanium dioxide

Perfluorooctanoic acid (PFOA) is potentially toxic and exceptionally stable attributed to its robust CF bond, which is hard to be removed by UV/TiO2 systems. In this research, bismuth nanoparticle (Bi NP) modified titanium oxides (Bi/TiO2) were synthesized by a simple photochemical deposition-calcination method and were applied as photocatalysts for the first time to degrade PFOA. The removal rate of 50 mg/L PFOA reached 99.3 % with 58.6 % defluorination rate after 30 min of irradiation via a mercury lamp. Bi/TiO2 exhibited superior performance in PFOA degradation compared to commercial photocatalysts (TiO2, Ga2O3, Bi2O3 and In2O3). In addition, Bi/TiO2 showed high degradation activity under actual sunlight, achieved 100 % removal rate and 59.3 % defluorination rate within 2 h. Bi NPs increase the light trapping ability of Bi/TiO2 and promote the separation of photogenerated electron-hole pairs via local surface plasmon resonance (LSPR) effect, which results in more photogenerated holes (h+) and hydroxyl radicals (OH). Combined with DFT calculations and intermediate detections, the degradation reaction is initiated from the oxidation of the PFOA carboxyl group via h+, followed by the loss of the CF2 unit step by step with the participation of OH. This work presents a novel approach for the practical implementation of TiO2-based photocatalysts to achieve highly efficient photocatalytic degradation of perfluorocarboxylic acids (PFCAs).

Formation of nitrated naphthalene in the sulfate radical oxidation process in the presence of nitrite

Polycyclic aromatic hydrocarbons (PAHs) have become a global environmental concern due to their potential hazardous implication for human health. In this study, we found that sulfate radical (SO4•-) could effectively degrade naphthalene (NAP), a representative PAH in groundwaters, generating 1-naphthol. This intermediate underwent further degradation, yielding ring-opening products including phthalic acid and salicylic acid. However, the presence of nitrite (NO2-), a prevalent ion in subsurface environments, was observed to compete with NAP for SO4•-, thus slowing down the NAP degradation. The reaction between NO2- and SO4•- generated a nitrogen dioxide radical (NO2•). Concurrently, in-situ formed 1-naphthol underwent further oxidization to the 1-naphthoxyl radical by SO4•-. The coupling of 1-naphthoxyl radicals with NO2• gave rise to a series of nitrated NAP, namely 2-nitro-1-naphthol, 4-nitro-1-naphthol, and 2,4-dinitro-1-naphthol. In addition, the in-situ formed phthalic acid and salicylic acid also underwent nitration, generating nitrophenolic products, although this pathway appeared less prominent than the nitration of 1-naphthol. When 10 μΜ NAP was subjected to heat activated peroxydisulfate oxidation in the presence of 10 μΜ NO2-, the total yield of nitrated products reached 0.730 μΜ in 120 min. Overall, the presence of NO2- dramatically altered the behavior of NAP degradation by SO4•- oxidation and contributed to the formation of toxic nitrated products. These findings raise awareness of the potential environmental risks associated with the application of SO4•--based oxidation processes for the remediation of PAHs-polluted sites in presence of NO2-.

Fate of sulfamethoxazole in wetland sediment under controlled redox conditions

Redox condition is an important controlling factor for contaminant removal in constructed wetlands; however, the redox-sensitivity of antibiotic removal in wetland sediments under controlled conditions with specific electron acceptors remains unclear. Here, using a 14C radioactive tracer, we explored fate of sulfamethoxazole (SMX) in a wetland sediment slurry under oxic, nitrate-reducing, iron-reducing, and methanogenic conditions. In the sterile treatment, unlike the comparable SMX dissipation from the water phase under four redox conditions, non-extractable residues (NERs) of SMX was highest formed in the sediment under oxic condition, mainly in sequestered and ester/amide-linked forms. Microorganisms markedly promoted SMX transformation in the slurry. The dissipation rate of SMX and its transformation products (TPs) followed the order: oxic ≈ iron-reducing > methanogenic >> nitrate-reducing conditions, being consistent with the dynamics of microbial community in the sediment, where microbial diversity was greater and networks connectivity linking dominant bacteria to SMX transformation were more complex under oxic and iron-reducing conditions. Kinetic modeling indicated that the transformation trend of SMX and its TPs into the endpoint pool NERs depended on the redox conditions. Addition of wetland plant exudates and sediment dissolved organic matter at environmental concentrations affected neither the abiotic nor the biotic transformation of SMX. Overall, the iron-reducing condition was proven the most favorable and eco-friendly for SMX transformation, as it resulted in a high rate of SMX dissipation from water without an increase in toxicity and subsequent formation of significant stable NERs in sediment. Our study comprehensively revealed the abiotic and biotic transformation processes of SMX under controlled redox conditions and demonstrated iron-reducing condition allowing optimal removal of SMX in constructed wetlands.

Transport and health risk of legacy and emerging per-and polyfluoroalkyl substances in the water cycle in an urban area, China: Polyfluoroalkyl phosphate esters are of concern

Polyfluoroalkyl phosphate esters (PAPs) are a group of emerging alternatives to the legacy per- and polyfluoroalkyl substances (PFAS). To better understand the transport and risk of PAPs in the water cycle, 21 PFAS including 4 PAPs and 17 perfluoroalkyl acids were investigated in multiple waterbodies in an urban area, China. PFAS concentrations ranged from 85.8 to 206 ng/L, among which PAPs concentrations ranged from 35.0 to 71.8 ng/L, in river and lake water with major substances of perfluorooctanoic acid (PFOA), 6:2 fluorotelomer phosphate (6:2 monoPAP), and 8:2 fluorotelomer phosphate (8:2 monoPAP). As transport pathways, municipal wastewater and precipitation were investigated for PFAS mass loading estimation, and PAPs transported via precipitation more than municipal wastewater discharge. Concentrations of PFAS in tap water and raw source water were compared, and PAPs cannot be removed by drinking water treatment. In tap water, PFAS concentrations ranged from 132 to 271 ng/L and among them PAPs concentrations ranged from 41.6 to 61.9 ng/L. Human exposure and health risk to PFAS via drinking water were assessed, and relatively stronger health risks were induced from PFOS, PAPs, and PFOA. The environmental contamination and health risk of PAPs are of concern, and management implications regarding their sources, exposure, and hazards were raised.

Emerging and legacy per- and polyfluoroalkyl substances (PFAS) in fluorochemical wastewater along full-scale treatment processes: Source, fate, and ecological risk

The increasing applications of emerging per- and polyfluoroalkyl substances (PFAS) have raised global concern. However, the release of emerging PFAS from the fluorochemical industry remains unclear. Herein, the occurrence of 48 emerging and legacy PFAS in wastewater from 10 fluorochemical manufacturers and mass flows of PFAS in a centralized wastewater treatment plant were investigated. Their distribution and ecological risk in neighboring riverine water were also evaluated. In wastewater from fluorochemical manufacturers, PFAS concentrations were in the range of 14,700-5200,000 ng/L and 2 H,2 H-perfluorooctanoic acid (6:2 FTCA), perfluorooctanoic acid (PFOA), N-ethyl perfluorooctane sulfonamide (N-EtFOSA), and 1 H,1 H,2 H,2 H-perfluorodecanesulfonate (8:2 FTS) were the major PFAS detected. Several PFAS displayed increased mass flows after wastewater treatment, especially PFOA and 6:2 FTCA. The mass flows of PFAS increased from - 20% to 233% after the activated sludge system but decreased by only 0-13% after the activated carbon filtration. In riverine water, PFAS concentrations were in the range of 5900-39,100 ng/L and 6:2 FTCA, 1 H,1 H,2 H,2 H-perfluorodecyl phosphate monoester (8:2 monoPAP), 1 H,1 H,2 H,2 H-perfluorooctyl phosphate monoester (6:2 monoPAP), PFOA, and perfluorohexanoic acid (PFHxA) were the major PFAS detected. PFOA and 6:2 FTCA exhibited comparable hazard quotients for ecological risk. Current wastewater treatment processes cannot fully remove various PFAS discharged by fluorochemical manufacturers, and further investigations on their risk are needed for better chemical management.

Adsorption-desorption of Atrazine with 9 Agricultural Soils in China

In this work, the characteristics and mechanisms for atrazine adsorption-desorption with 9 types of soils were investigated with batch equilibrium studies, elemental analyses, infrared spectroscopy, and UV‒visible spectroscopy. The atrazine sorption data for the 9 soils showed better fits with the Freundlich model than the Langmuir model, except with Red earth in Jiangxi (REJ) The results showed that the adsorption capacity was positively correlated with the organic matter (OM) content and negatively correlated with cation-exchange capacity (CEC) and pH. UV‒visible spectroscopy showed that dissolved organic matter (DOM) in the soil enhanced atrazine adsorption, but the adsorption on different DOM fractions was quite different. In addition, the infrared spectra revealed differences in the functional groups of soils and these functional groups may drive the adsorption process via hydrogen bonding and coordination with the -NH2 groups in atrazine.

Risk Factors for Locoregional Recurrence and Distant Metastasis in 143 Patients with Adenoid Cystic Carcinoma of the External Auditory Canal

AIMS

Adenoid cystic carcinoma (ACC) grows slowly and is characterised by potential recurrence and metastasis to distant organs. This study aimed to evaluate the risk factors for locoregional recurrence (LRR) and distant metastasis in patients with ACC of the external auditory canal (EAC).

MATERIALS AND METHODS

Demographic, pathological, therapeutic and survival data of 143 patients with EAC ACC were reviewed in this study. Univariate and multivariate Cox proportional hazard regression analyses were carried out to determine the risk factors for LRR and distant metastasis. Factors associated with overall survival after LRR and distant metastasis were also analysed.

RESULTS

During a median follow-up of 49 months, 31 of 143 patients were observed with LRR and 34 developed distant metastasis. Bone invasion and histological subtype were independent risk factors for locoregional recurrence-free survival. T stage and LRR were independent risk factors for distant metastasis-free survival. Salvage surgery and adjuvant radiotherapy or chemoradiotherapy for LRR resulted in better survival, whereas extrapulmonary metastasis and LRR were associated with a higher risk of poor survival after distant metastasis.

CONCLUSION

Patients with distant metastases, especially those with LRR, are at significant risk of poor prognosis. Our findings emphasise the importance of long-term regular follow-up and recommend surgical intervention with radiotherapy for recurrent EAC ACC.

Inventory, source and health risk assessment of nitrated and parent PAHs in agricultural soils over a rural river in Southeast China

Nitrated polycyclic aromatic hydrocarbons (NPAHs) have become a concerning topic because of their widespread occurrence and carcinogenicity. However, studies on NPAHs in soils, especially in agricultural soils, are still limited. In this study, a systematic monitoring campaign of 15 NPAHs and 16 polycyclic aromatic hydrocarbons (PAHs) was performed in agricultural soils from the Taige Canal basin in 2018, which is a typical agricultural activity area of the Yangtze River Delta. The total concentration of NPAHs and PAHs ranged from 14.4 to 85.5 ng g^-1 and 118-1108 ng g^-1, respectively. Among the target analytes, 1,8-dinitropyrene and fluoranthene were the most predominant congeners accounting for 35.0% of ∑₁₅NPAHs and 17.2% of ∑₁₆PAHs, respectively. Four-ring NPAHs and PAHs were predominant, followed by three-ring NPAHs and PAHs. NPAHs and PAHs had a similar spatial distribution pattern with high concentrations in the northeastern Taige Canal basin. The soil mass inventory of ∑₁₆PAHs and ∑₁₅NPAHs was evaluated to be 31.7 and 2.55 metric tons, respectively. Total organic carbon had a significant impact on the distribution of PAHs in soils. The correlation between PAH congeners in agricultural soils was higher than that between NPAH congeners. Based on diagnostic ratios and principal component analysis-multiple linear regression model, vehicle exhaust emission, coal combustion, and biomass combustion were the predominant sources of these NPAHs and PAHs. According to the lifetime incremental carcinogenic risk model, the health risk posed by NPAHs and PAHs in agricultural soils of the Taige Canal basin was virtually negligible. The total health risk in soils of the Taige Canal basin to adults was slightly higher than that to children.

MK8617 inhibits M1 macrophage polarization and inflammation via the HIF-1α/GYS1/UDPG/P2Y14 pathway

Background

Nonresolving inflammation is a major driver of disease and needs to be taken seriously. Hypoxia-inducible factor (HIF) is closely associated with inflammation. Hypoxia-inducible factor-prolyl hydroxylase inhibitors (HIF-PHIs), as stabilizers of HIF, have recently been reported to have the ability to block inflammation. We used MK8617, a novel HIF-PHI, to study its effect on macrophage inflammation and to explore its possible mechanisms.

Methods

Cell viability after MK8617 and lipopolysaccharide (LPS) addition was assessed by Cell Counting Kit-8 (CCK8) to find the appropriate drug concentration. MK8617 pretreated or unpretreated cells were then stimulated with LPS to induce macrophage polarization and inflammation. Inflammatory indicators in cells were assessed by real-time quantitative reverse-transcription polymerase chain reaction (qRT-PCR), western blot (WB) and immunofluorescence (IF). The level of uridine diphosphate glucose (UDPG) in the cell supernatant was measured by ELISA. Purinergic G protein-coupled receptor P2Y₁₄, as well as hypoxia-inducible factor-1α (HIF-1α) and glycogen synthase 1 (GYS1) were detected by qRT-PCR and WB. After UDPG inhibition with glycogen phosphorylase inhibitor (GPI) or knockdown of HIF-1α and GYS1 with lentivirus, P2Y₁₄ and inflammatory indexes of macrophages were detected by qRT-PCR and WB.

Results

MK8617 reduced LPS-induced release of pro-inflammatory factors as well as UDPG secretion and P2Y₁₄ expression. UDPG upregulated P2Y₁₄ and inflammatory indicators, while inhibition of UDPG suppressed LPS-induced inflammation. In addition, HIF-1α directly regulated GYS1, which encoded glycogen synthase, an enzyme that mediated the synthesis of glycogen by UDPG, thereby affecting UDPG secretion. Knockdown of HIF-1α and GYS1 disrupted the anti-inflammatory effect of MK8617.

Conclusions

Our study demonstrated the role of MK8617 in macrophage inflammation and revealed that its mechanism of action may be related to the HIF-1α/GYS1/UDPG/P2Y₁₄ pathway, providing new therapeutic ideas for the study of inflammation.

Photo-transformation of acetaminophen sensitized by fluoroquinolones in the presence of bromide

Fluoroquinolones (FQs) are a class of antibiotics with emerging concern. This study investigated the photochemical properties of two representative FQs, i.e., norfloxacin (NORF) and ofloxacin (OFLO). Results showed that both FQs could sensitize the photo-transformation of acetaminophen under UV-A irradiation, during which excited triplet state (³FQ*) was the main active species. In the presence of 3 mM Br^‾, the photolysis rate of acetaminophen increased by 56.3% and 113.5% in the solutions with 10 μM NORF and OFLO, respectively. Such an effect was ascribed to the generation of reactive bromine species (RBS), which was verified by 3,5-dimethyl-1H-pyrazole (DMPZ) probing approach. ³FQ* reacts with acetaminophen through one-electron transfer, producing radical intermediates which then couple to each other. Presence of Br^‾ did not lead to the formation of brominated products but the same coupling products, which suggests that radical bromine species, rather than free bromine, were responsible for the accelerated acetaminophen transformation. According to the identified reaction products and assisted with the theoretical computation, the transformation pathways of acetaminophen under UV-A irradiation were proposed. The results reported herein suggest that sunlight-driven reactions of FQs and Br^‾ may influence the transformation of coexisting pollutants in surface water environments.

Single-cell profiling of the copy-number heterogeneity in colorectal cancer

BACKGROUND

With functionally heterogeneous cells, tumors comprise a complex ecosystem to promote tumor adaptability and evolution under strong selective pressure from the given microenvironment. Diversifying tumor cells or intra-tumor heterogeneity is essential for tumor growth, invasion, and immune evasion. However, no reliable method to classify tumor cell subtypes is yet available. In this study, we introduced the single-cell sequencing combined with copy number characteristics to identify the types of tumor cells in microsatellite stable (MSS) colorectal cancer (CRC).

METHODS

To characterize the somatic copy number alteration (SCNA) of MSS CRC in a single cell profile, we analyzed 26 tissue samples from 19 Korean patients (GSE132465, the Samsung Medical Center [SMC] dataset) and then verified our findings with 15 tissue samples from five Belgian patients (GSE144735, the Katholieke Universiteit Leuven 3 [KUL3] dataset). The Cancer Genome Atlas (TCGA) cohort, GSE39582 cohort, and National Cancer Center (NCC) cohort (24 MSS CRC patients were enrolled in this study between March 2017 and October 2017) were used to validate the clinical features of prognostic signatures.

RESULTS

We employed single cell RNA-sequencing data to identify three types of tumor cells in MSS CRC by their SCNA characteristics. Among these three types of tumor cells, C1 and C3 had a higher SCNA burden; C1 had significant chromosome 13 and 20 amplification, whereas C3 was the polar opposite of C1, which exhibited deletion in chromosome 13 and 20. The three types of tumor cells exhibited various functions in the tumor microenvironment and harbored different mutations. C1 and C2 were linked to the immune response and hypoxia, respectively, while C3 was critical for cell adhesion activity and tumor angiogenesis. Additionally, one gene ( OLFM4 ) was identified as epithelium-specific biomarker of better prognosis of CRC (TCGA cohort: P  = 0.0110; GSE39582 cohort: P  = 0.0098; NCC cohort: P  = 0.0360).

CONCLUSIONS

On the basis of copy number characteristics, we illustrated tumor heterogeneity in MSS CRC and identified three types of tumor cells with distinct roles in tumor microenvironment. By understanding heterogeneity in the intricate tumor microenvironment, we gained an insight into the mechanisms of tumor evolution, which may support the development of therapeutic strategies.

Mapping Pu'er tea plantations from GF-1 images using Object-Oriented Image Analysis (OOIA) and Support Vector Machine (SVM)

Tea is the most popular drink worldwide, and China is the largest producer of tea. Therefore, tea is an important commercial crop in China, playing a significant role in domestic and foreign markets. It is necessary to make accurate and timely maps of the distribution of tea plantation areas for plantation management and decision making. In the present study, we propose a novel mapping method to map tea plantation. The town of Menghai in the Xishuangbanna Dai Autonomous Prefecture, Yunnan Province, China, was chosen as the study area, andgg GF-1 remotely sensed data from 2014-2017 were chosen as the data source. Image texture, spectral and geometrical features were integrated, while feature space was built by SEparability and THresholds algorithms (SEaTH) with decorrelation. Object-Oriented Image Analysis (OOIA) with a Support Vector Machine (SVM) algorithm was utilized to map tea plantation areas. The overall accuracy and Kappa coefficient ofh the proposed method were 93.14% and 0.81, respectively, 3.61% and 0.05, 6.99% and 0.14, 6.44% and 0.16 better than the results of CART method, Maximum likelihood method and CNN based method. The tea plantation area increased by 4,095.36 acre from 2014 to 2017, while the fastest-growing period is 2015 to 2016.

Occurrence, Spatial Distribution and Health Risk of Hexabromocyclododecane (HBCD) in Source Water in the Lower Yangtze River, China

The occurrence and health risk of hexabromocyclododecane (HBCD), a brominated flame retardant with its three diastereoisomers, in drinking water sources in the lower Yangtze River in China was investigated. Its concentration ranged from 0.58 to 3.71 ng/L and averaged at 1.18 ng/L. Among the three diastereoisomers of α-, β- and γ-HBCD, γ-HBCD was the dominant one accounting for 44% (ranging 27-82%) to the total concentration. Source of HBCD in the contaminated site was discussed according to its spatial distribution and diastereoisomer profile. The margin of exposure (MOE) approach was applied to evaluate the health risk of HBCD through drinking water by estimated exposure and derived reference dose. The MOE was 17 for adults and 12 for children in the worst-case scenario, suggesting a trivial health concern.

Experimental and theoretical study on Fe(VI) oxidative degradation of dichlorophen in water: Kinetics and reaction mechanisms

Dichlorophenol (DCP), a commonly used fungicide and insecticide, is widely found in waters and wastewaters. Herein, the degradation of DCP by Ferrate (Fe(VI)) in different matrices was comprehensively investigated. In pure water, a complete removal of DCP was achieved in 300 s at [Fe(VI)]:[DCP] molar ratio of 2:1. The presence of HA (10 mg L^-1) inhibited DCP degradation to a certain extent. A total of twenty degradation products were identified by HPLC/MS analysis. Based on these products, reaction pathways including the cleavage of C-C bridge bond, hydroxylation, and radical coupling were proposed. These reaction mechanisms were further rationalized by theoretical calculations. The analyses of Wiberg bond orders and transition state indicated that C₇-C₈ bond was the most vulnerable site for cleavage, and C₁₂ site was the most likely site for hydroxyl addition. Mulliken atomic spin densities distribution suggested that self-coupling products was easily generated via C-O-C coupling ways. Finally, the feasibility of applying Fe(VI) to degrade DCP (20 μM) in a municipal wastewater effluent and a lake water was evaluated and verified. The findings in this study are of relevance in designing Fe(VI)-based treatment strategy for chlorine-containing persistent pesticides.

[Clinical value of a differentiation prediction model for invasive lung adenocarcinoma]

Objective: To investigate the value of predicting the degree of differentiation of pulmonary invasive adenocarcinoma (IAC) based on CT image radiomics model and the expression difference of immunohistochemical factors between different degrees of differentiation of lesions. Methods: The clinicopathological data of patients with pulmonary IAC confirmed by surgical pathology in the Affiliated Huai'an First People's Hospital to Nanjing Medical University from December 2017 to September 2018 were collected. High-throughput feature acquisition was performed for all outlined regions of interest, and prediction models were constructed after dimensionality reduction by the minimum absolute shrinkage operator. Receiver operating characteristic curve was used to assess the predictive efficacy of clinical characteristic model, radiomics model and individualized prediction model combined with both to identify the degree of pulmonary IAC differentiation, and immunohistochemical expressions of Ki-67, NapsinA and TTF-1 were compared between groups with different degrees of IAC differentiation using rank sum test. Results: A total of 396 high-throughput features were extracted from all IAC lesions, and 10 features with high generalization ability and correlation with the degree of IAC differentiation were screened. The mean radiomics score of poorly differentiated IAC in the training group (1.206) was higher than that of patients with high and medium differentiation (0.969, P=0.001), and the mean radiomics score of poorly differentiated IAC in the test group (1.545) was higher than that of patients with high and medium differentiation (-0.815, P<0.001). The differences in gender (P<0.001), pleural stretch sign (P=0.005), and burr sign (P=0.033) were statistically significant between patients in the well and poorly differentiated IAC groups. Multifactorial logistic regression analysis showed that gender and pleural stretch sign were related to the degree of IAC differentiation (P<0.05). The clinical feature model consisted of age, gender, pleural stretch sign, burr sign, tumor vessel sign, and vacuolar sign, and the individualized prediction model consisted of gender, pleural stretch sign, and radiomic score, and was represented by a nomogram. The Akaike information standard values of the radiomics model, clinical feature model and individualized prediction model were 54.756, 82.214 and 53.282, respectively. The individualized prediction model was most effective in identifying the degree of differentiation of pulmonary IAC, and the area under the curves (AUC) of the individualized prediction model in the training group and the test group were 0.92 (95% CI: 0.86-0.99) and 0.88 (95% CI: 0.74-1.00, respectively). The AUCs of the radiomics group model for predicting the degree of differentiation of pulmonary IAC in the training group and the test group were 0.91 (95% CI: 0.83-0.98) and 0.87 (95% CI: 0.72-1.00), respectively. The AUCs of the clinical characteristics model for predicting the degree of differentiation of pulmonary IACs in the training and test groups were 0.75 (95% CI: 0.63-0.86) and 0.76 (95% CI: 0.59-0.94), respectively. The expression level of Ki-67 in poorly differentiated IAC was higher than that in well-differentiated IAC (P<0.001). The expression levels of NapsinA, TTF-1 in poorly differentiated IAC were higher than those in well-differentiated IAC (P<0.05). Conclusions: Individualized prediction model consisted of gender, pleural stretch sign and radiomics score can discriminate the differentiation degree of IAC with the best performance in comparison with clinical feature model and radiomics model. Ki-67, NapsinA and TTF-1 express differently in different degrees of differentiation of IAC.

Transformation of amino acids and formation of nitrophenolic byproducts in sulfate radical oxidation processes

In this study, the transformation of five amino acids (AAs), i.e., glycine (GLY), alanine (ALA), serine (SER), aspartic acid (ASP), and methionine (MET), in a heat activated peroxydisulfate (PDS) oxidation process was investigated. Experimental data showed that the nitrogen in the AA molecules was oxidized to NH₄⁺ and nitrate (NO₃^-) sequentially. However, in the presence of natural organic matter (NOM), nitrophenolic byproducts including 4-nitrophenol, 2,4-dinitrophenol, 5-nitrosalicylic acid, 3,5-dinitrosalicylic acid were formed. The nitrogen dioxide radical (NO₂^•) generated during the transformation of NH₄⁺ to NO₃^- was presumed to be the key nitrating agent. It reacted with phenolic moieties in NOM and was transformed to nitrophenolic byproducts. Among the selected AAs, SER showed the highest nitrophenolic byproducts formation potential. A total yield of 0.258 μM was observed at the condition of 0.1 mM SER, 5 mg/L (as TOC) NOM, 2 mM PDS, and pH 7.0. The formation from GLY and ALA was lowest, only 0.009 μM detected under the same conditions. The nitrophenolic byproducts formation potential of the AAs was positively related to their reactivity toward SO₄^•- and can be explained by the local nucleophilicity index (N_k). These findings underline the potential risks in the application of SO₄^•- based oxidation technology.

Ecotoxicological risk ranking of 19 metals in the lower Yangtze River of China based on their threats to aquatic wildlife

With thousands of chemicals discharged into the aquatic environment, it is necessary to identify those that are likely to be having the greatest impact on wildlife to better protect the ecosystem. A risk ranking approach was developed to compare the ecotoxicological risk of chemicals on aquatic wildlife with a wide range of environmental measurement data and ecotoxicity data. Nineteen metals including some rarely monitored ones including antimony (Sb), molybdenum (Mo), cobalt (Co), vanadium (V), titanium (Ti) and thallium (Tl) in the lower Yangtze River were risk ranked as a case study. The risk ranking approach was conducted in three tiers: general risk ranking, lethal effects vs. non-lethal effects risk ranking, and species group-specific risk ranking. Iron, copper and titanium were identified as being of greatest concern. The contamination of iron, zinc, copper and nickel was widespread and may have already harmed wildlife according to the overlap between ecotoxicity and monitored levels. Based on this analysis, the risk from copper and some rarely monitored metals (titanium and boron) may have been underestimated. Greater efforts to reduce copper, iron and titanium contamination could make an important difference to the health of Chinese freshwater organisms in the Yangtze River.

Transformation of bromide and formation of brominated disinfection byproducts in peracetic acid oxidation of phenol

Peracetic acid (PAA) has attracted increasing attention in wastewater treatment as a disinfectant. However, the transformation of bromide (Br^-) during PAA oxidation of bromide-containing wastewater has not been fully explored. This study showed that Br^- could be oxidized by PAA to free bromine which reacted with phenol to form organic bromine. At pH 7.0, more than 35.2% inorganic Br^- was converted to organic bromines in 4 h. At acidic conditions, the conversion ratio was even higher, reaching 69.9% at pH 2.8. Most of the organic bromines were presented as bromophenols (i.e., 2-bromophenol, 4-bromophenol, and 2,4-dibromophenol), while regulated brominated disinfection byproducts (Br-DBPs, i.e., bromoform and bromoacetic acids) only accounted for a tiny fraction of total organic bromine. Similar results were observed when PAA was applied to natural organic matter (NOM) or wastewater in presence of Br^-. The organic bromine yield reached 56.6 μM in the solution containing 0.1 mM Br^- and 2 mg/L NOM initially. Among them, only 1.00 μM bromoform and 0.16 μM dibromoacetic acid were found. Similarly, regulated Br-DBPs only accounted for 28.3% of the organic bromine in a real wastewater effluent treated with PAA. All these data show that monitoring regulated DBPs cannot fully indicate the potential environmental risk of the application of PAA to wastewater.

Photodegradation of benzophenones sensitized by nitrite

Benzophenone UV filters (BPs) are a group of contaminants of emerging concern due to their widespread occurrence and adverse effects on aquatic ecosystems. In this study, the transformation of BPs by nitrite sensitized photodegradation was comprehensively investigated. OH and NO₂ generated by nitrite photolysis reacted with BPs, forming hydroxylated and nitrated products, respectively. Kinetic modeling revealed that the steady-state concentrations of NO₂ were approximately six orders of magnitude higher than those of OH in the UV/nitrite process, although the second-order rate constants of NO₂ reactions with BPs were six orders of magnitude lower. With the increase in nitrite concentration, BPs degradation was accelerated, and the contribution of NO₂ increased as well. At initial nitrite concentration of 10 μM, the contributions of OH and NO₂ to the degradation of 2,4-dihydroxybenzophenone (BP1) were 66.1% and 21.5%, respectively. However, NO₂ only contributed a tiny fraction to the degradation of 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (BP4), due to the presence of an electron-withdrawing sulfonate group in the molecule. Natural organic matter (NOM) inhibited the nitrite sensitized degradation of BPs, due to light screening and radical scavenging effects. This study suggests that BPs can be effectively transformed in sunlit waters in the presence of nitrite, leading to nitrated products.

Screening and identification of key biomarkers of papillary renal cell carcinoma by bioinformatic analysis

Background

Papillary renal cell carcinoma (PRCC) is the most common type of renal cell carcinoma after clear cell renal cell carcinoma (ccRCC). Its pathological classification is controversial, and its molecular mechanism is poorly understood. Therefore, the identification of key genes and their biological pathways is of great significance to elucidate the molecular mechanisms of PRCC occurrence and progression.

Methods

The PRCC-related datasets GSE7023, GSE48352 and GSE15641 were downloaded from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were identified, and gene ontology (GO) term enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were performed. Cytoscape and STRING were used to construct the protein-protein interaction network (PPI) and perform module analysis to identify hub genes and key pathways. A heatmap of hub genes was constructed using the UCSC cancer genomics browser. Overall survival and recurrence-free survival of patients stratified by the expression levels of hub genes were analysed using Kaplan-Meier Plotter. The online database UALCAN was applied to analyse gene expression based on tissue type, stage, subtype and race.

Results

A total of 214 DEGs, specifically, 205 downregulated genes and 9 upregulated genes, were identified. The DEGs were mainly enriched in angiogenesis, kidney development, oxidation-reduction process, metabolic pathways, etc. The 17 hub genes identified were mainly enriched in the biological processes of angiogenesis, cell adhesion, platelet degranulation, and leukocyte transendothelial migration. Survival analysis showed that EGF, KDR, CXCL12, REN, PECAM1, CDH5, THY1, WT1, PLAU and DCN might be related to the carcinogenesis, metastasis or recurrence of PRCC. UALCAN analysis showed that low expression of PECAM1 and PLAU in PRCC tissues was related to stage, subtype and race.

Conclusions

The DEGs and hub genes identified in the present study provide insight into the specific molecular mechanisms of PRCC occurrence and development and may be potential molecular markers and therapeutic targets for the accurate classification and efficient diagnosis and treatment of PRCC.

Differentiated activities of decorin and biglycan in the progression of post-traumatic osteoarthritis

OBJECTIVE

To delineate the activities of decorin and biglycan in the progression of post-traumatic osteoarthritis (PTOA).

DESIGN

Three-month-old inducible biglycan (BgniKO) and decorin/biglycan compound (Dcn/BgniKO) knockout mice were subjected to the destabilization of the medial meniscus (DMM) surgery to induce PTOA. The OA phenotype was evaluated by assessing joint structure and sulfated glycosaminoglycan (sGAG) staining via histology, surface collagen fibril nanostructure and calcium content via scanning electron microscopy, tissue modulus via atomic force microscopy-nanoindentation, as well as subchondral bone structure and meniscus ossification via micro-computed tomography. Outcomes were compared with previous findings in the inducible decorin (DcniKO) knockout mice.

RESULTS

In the DMM model, BgniKO mice developed similar degree of OA as the control (0.44 [-0.18 1.05] difference in modified Mankin score), different from the more severe OA phenotype observed in DcniKO mice (1.38 [0.91 1.85] difference). Dcn/BgniKO mice exhibited similar histological OA phenotype as DcniKO mice (1.51 [0.97 2.04] difference vs control), including aggravated loss of sGAGs, salient surface fibrillation and formation of osteophyte. Meanwhile, Dcn/BgniKO mice showed further cartilage thinning than DcniKO mice, resulting in the exposure of underlying calcified tissues and aberrantly high surface modulus. BgniKO and Dcn/BgniKO mice developed altered subchondral trabecular bone structure in both Sham and DMM groups, while DcniKO and control mice did not.

CONCLUSION

In PTOA, decorin plays a more crucial role than biglycan in regulating cartilage degeneration, while biglycan is more important in regulating subchondral bone structure. The two have distinct activities and modest synergy in the pathogenesis of PTOA.

Perfluoroalkyl substances in drinking water sources along the Yangtze River in Jiangsu Province, China: Human health and ecological risk assessment

Perfluoroalkyl substances (PFASs) in source water is of growing concern for its adverse effects on human health and wildlife as well. The Yangtze River is the vital drinking water source in Jiangsu Province of China, but little attention has been paid on PFASs. The occurrence, spatial distribution and temporal trend of PFASs in 21 water sources along the Jiangsu section of the Yangtze River was investigated with sampling from 2018 to 2020. Moreover, health risk of PFASs was assessed by estimated intake dose and derived tolerable intake dose, while ecological risk was assessed by selected effect concentration and environmental exposure. PFASs concentrations in source water ranged from 12.0 to 128 ng/L, with perfluorooctanoic acid (PFOA) as the dominated congener. Fluorine chemical industry lead to a great increase of perfluorohexanoic acid (PFHxA) in its nearest water source. The estimated daily intake of PFASs through drinking was 0.54 and 0.82 ng/kg bw/day for adults and children. The major health risk was from perfluorooctane sulfonate (PFOS) and PFOA for their toxicity on liver, reproduction, development and immunity, with the maximum hazard quotient of 0.029 and 0.043 for adults and children in the worst scenario. The ecological risks from PFASs on nine species groups ranged from 2.7 × 10-10 to 5.2. PFOA and Perfluorobutane sulfonate (PFBS) were causing significant risk on wildlife, particularly on worms, mussels, and fish, which may further influence the structure and processes in the foodweb. Overall, PFASs, especially PFOS, PFOA and PFBS, induced considerable risk on human health and aquatic species in some hotspot area. It would be necessary to include them into monitoring in China and develop standards for different protection purposes.

Biochar applications combined with paddy-upland rotation cropping systems benefit the safe use of PAH-contaminated soils: From risk assessment to microbial ecology

This study aimed to establish a method allowing the safe use of polycyclic aromatic hydrocarbon (PAH)-contaminated soils through the combination of biochar applications and different cropping systems. The impact of biochar applications under different cropping systems on the human health risks of PAHs and soil microbiology was elucidated. The residual PAHs were the lowest in rhizosphere soils amended with 2% corn straw-derived biochar pyrolyzed at 300 °C (CB300) under the paddy-upland rotation cropping (PURC) system. Human health risks resulting from the ingestion of PAH-contaminated carrot roots / rice grains under the PURC system were significantly lower than those under continuous upland cropping systems. The greatest diversity, richness and network complexity of soil microbial communities occurred under the PURC system combined with the 2% CB300 treatment. Soil microbial functions associated with soil health and PAH biodegradation were enhanced under this strategy, while the pathogen group was inhibited. Primarily owing to its high sorption capacity, bamboo-derived biochar pyrolyzed at 700 °C realized in the reduction of PAHs, but weakly influenced shifts in soil microbial communities. Overall, the combination of PURC systems and low-temperature-pyrolyzed nutrient-rich biochar could efficiently reduce the human health risks of PAHs and improve soil microbial ecology in agricultural fields.

Genetic polymorphisms and cardiovascular outcomes in Chinese patients undergoing PCI and treated with clopidogrel and aspirin

Background

Genetic polymorphisms of key proteins involved in clopidogrel absorption, metabolism, and action may contribute to variability in platelet inhibition in patients undergoing percutaneous coronary intervention (PCI), but their impacts on cardiovascular outcomes remain unclear.

Purpose

To examine the associations between genetic polymorphisms and cardiovascular outcomes in Chinese patients undergoing PCI and treated with clopidogrel and aspirin.

Methods

This prospective cohort study consecutively enrolled 2,453 post-PCI patients treated with clopidogrel and aspirin. Adenosine diphosphate-induced platelet aggregation was measured by light transmission aggregometry. A total of 40 single nucleotide polymorphisms (SNPs) of 18 genes selected according to published studies were investigated using an improved multiplex ligation detection reaction technique. The primary outcome was major adverse cardiovascular event (MACE), the composite of cardiovascular death, non-fatal myocardial infarction (MI), and ischemic stroke within one year after PCI.

Results

We restricted the analyses to the first 1,452 patients who had finished one-year follow-up and complete data on genotyping and platelet aggregation. 44 (3.03%) patients suffered MACE. Among the 40 SNPs, only the A-allele carriers of CYP2C19*2 had a significant higher risk of MACE (adjusted HR 2.05; 95% CI, 1.01–4.19; p=0.048) and platelet aggregation than non-A-carriers after adjusting age, sex, MI presentation, and left ventricular ejection fraction. CYP2C19*3, CYP2B6 rs3745274, and PEAR1 rs12041331 variants were also significantly associated with platelet aggregation (all p&lt;0.05) but not with MACE at 1 year.

Conclusion

About 54.2% of Chinese patients with PCI were A-allele carriers of CYP2C19*2, who face a two-fold higher risk of MACE than non-A-allele carriers in Chinese patients after PCI. It would help identify low clopidogrel responders and optimize antiplatelet therapy before drug administration.

Figure 1

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): National Natural Science Funding of China

Acute toxicity of fluazinam to aquatic organisms and its bioaccumulation in Brachydanio rerio

Fluazinam (FZN) is a dinitroaniline fungicide. To evaluate the environmental risk of FZN in aquatic environments and ascertain the potential danger to typical aquatic organisms in China, the acute toxicity of FZN to representative aquatic organisms, including Brachydanio rerio, Chlorella vulgaris Beij., Daphnia magna Straus, and Xenopus laevis, was measured, and its bioaccumulation properties in Brachydanio rerio were further investigated. The results showed that the acute toxicity of FZN to Brachydanio rerio and Xenopus laevis is extremely high, and the bioaccumulation factor BCF_8d of FZN in Brachydanio rerio ranges between 2287 and 3570, implying that it has high bioaccumulation properties. FZN poses a strong environmental risk for aquatic organisms and possesses great bioaccumulation properties, which may cause pollution to aquatic environments.

Change of disinfection byproducts formation potential of natural organic matter after exposure to persulphate and bicarbonate

Activated persulphate (PS) oxidation is a promising in situ remediation technology for groundwater and soils. Application of this technology to contaminated zones may result in a large quantity of PS residue in the subsurface environment due to inefficient activation and repeated injection. In this study, we demonstrated that natural organic matter (NOM) molecules could be reconfigured due to exposure to unactivated PS and bicarbonate, resulting in reduced disinfection byproducts formation potential in post chlorination process. Fourier transformed inferred spectrometry (FTIR), size exclusive chromotraghy (SEC), and mass spectrometry (MS) analysis revealed that hydroxylation and carboxylation of NOM occurred, followed by inter-molecular coupling via ether bonds. The change of both the reactivity toward free chlorine and molecular structure of NOM during PS/bicarbonate treatment was well mimicked by 3,5-dihydroxylbenzoic acid, suggesting that phenolic moieties in NOM molecules were the main sites underwent transformation in the PS/bicarbonate system. We propose that peroxymonocarbonate (HCO₄^-) formed upon the reaction between PS and bicarbonate was the main reactive species responsible for the reconfiguration of NOM. It selectively attacked the phenolic moieties via single-electron abstracting mechanism, leading to phenoxy radical intermediates which couple to each other via C-O-C bonds. The findings of this study shed light on the environmental behaviors and impacts of PS in groundwater environment.

The Role of Biochar in Reducing the Bioavailability and Migration of Persistent Organic Pollutants in Soil-Plant Systems: A Review

The amendment of biochar in soils contaminated with persistent organic pollutants (POPs) is an environmentally friendly in situ remediation measure. Numerous studies focused on the application of biochars to reduce the uptake of POPs by plants in soils. In this review, we summarized the role of biochar in reducing the migration of POPs in soil-plant systems. The mechanisms of biochar reducing the bioavailability of POPs in the soil, i.e. immobilization and promoted biodegradation, and the influencing factors are fully discussed. Especially in rhizosphere amended with biochar, the synergistic effect of POPs-root exudates-microorganisms on the reduced bioavailability of POPs is analyzed. This paper suggests that future researches should focus on the long-term environmental fate of POPs sorbed on high-temperature biochars and the long-term impacts of low-temperature biochars on the interaction of POPs-root exudates-rhizosphere microorganisms. All the above are necessary for efficient and safe use of biochar for remediating POP-contaminated farmland soils.

[Determination of diethyl aminoethyl hexanoate residues in apples by gas chromatography-mass spectrometry combined with improved QuEChERS]

A method was developed for the determination of diethyl aminoethyl hexanoate (DA-6) residues in apples by gas chromatography-mass spectrometry (GC-MS) combined with improved QuEChERS. The samples were first extracted with warm water, then, the extract was subjected to liquid-liquid re-extraction with dichloromethane, followed by rotary evaporation concentration. The residues were cleaned up with primary secondary amine (PSA). The analytes were separated on an HP-5 capillary column and detected using an EI source in the SIM mode. The recoveries ranged from 74.1% to 84.2% at three spiked levels, with relative standard deviations (RSDs) between 1.5% and 4.1%. The limit of detection and limit of quantification were 0.0024 mg/kg and 0.008 mg/kg, respectively. The developed method is sensitive, and practically applicable for the determination of DA-6 residues in apple samples.

Polybrominated diphenyl ethers (PBDEs) in soil and dust from plastic production and surrounding areas in eastern of China

Polybrominated diphenyl ethers (PBDEs) are a class of organic pollutants. They are used as flame retardants that caused worldwide environmental concern. This study investigated the occurrence of PBDEs in soils and dusts from three plastic manufacture plants and surrounding areas in Eastern China. A total of 13 PBDE congeners were detected using gas chromatography-mass spectrometer (electron impact ionization). The total concentrations of PBDEs range from 2.21 to 558, 19.7-4916, and 8.70-18,451 ng/g dry weight in the soils of three sampling areas, with mean of 1004 ng/g d w; in dusts, the concentrations range from 7240 to 10,469, 684-4482, and 193-3989 ng/g d w, with an overall mean of 3619 ng/g d w. The most abundant congener is the BDE-209, followed by BDE-153 and BDE-85. This indicates that the brominated flame retardant added in the plastic manufacture is mainly the commodity decabromodiphenyl ether. In comparison with other polluted areas around the world, the PBDE concentrations in the soils of the plastic manufacture plants are similar to those in soils of waste plastic disposal areas and PBDEs production sites, but orders of magnitude higher than those in agricultural soils, mountain soils and rural soils. Daily exposure was estimated using the average concentrations of the pollution sites. The hazard quotient shows that the PBDEs pose considerable human health risks, especially to children, to which attention should be paid.

Effect of activated carbon nanoparticles on lymph node harvest in patients with colorectal cancer

AIM

The aim was to examine the effect of activated carbon nanoparticles (ACNs) on lymph node retrieval in colorectal cancer (CRC) patients.

METHODS

This prospective randomized study of 80 subjects was performed between March 2016 and December 2016. Eighty patients with CRC were randomly divided into two groups, the ACN group and a control group. The patients in the ACN group were subjected to 1 ml of ACN injection in the subserosa around the tumour before colectomy and D3 lymphadenectomy. The patients in the control group received the same procedure without the injection of ACNs. After surgery, lymph nodes were isolated, and the greatest dimensions were measured by the same pathologist.

RESULTS

The average number of lymph nodes harvested from each patient was markedly more in the ACN group (31.3 ± 8.1) than in the control group (21.9 ± 5.3; P < 0.001), and the average number of lymph nodes less than 5 mm in greatest dimension was significantly more in the ACN group (11.9 ± 4.9) than in the control group (4.1 ± 2.4; P < 0.001). The ACN group (15/40) had a higher rate of Stage III patients compared to the control group (6/39; P = 0.026). Besides, the greatest dimension of 32.8% metastatic lymph nodes was less than 5 mm.

CONCLUSION

There is significant upstaging following the use of ACNs, which could find more involved nodes. Therefore, ACNs can be used as a tracer to harvest more lymph nodes in CRC patients, with improvement in the accuracy of pathological staging.

A study on molecular mechanisms of adiposis induced by long-term treatment of high-fat and high-sucrose in C57BL/6J mice

Adiposis is reputed as a twin disease of type 2 diabetes and greatly harmful to human health. In order to understand the molecular mechanisms of adiposis, the changes of physiological, pathological, epigenetic and correlative gene expression were investigated during the adiposis development of C57BL/6J mice induced by long time (9 months) high-fat and high-sucrose diet (HFSD) sustainably. The results showed that mRNA transcription level of the Leptin, Glut4 and Glut2 genes have been obviously changed, which exhibit a negative correlation with methylation on their promoter DNA. The results also revealed that HFSD induced higher level of DNA methyltransferase 1 (DNMT1) in fat tissue might play important role in regulating the changes of methylation pattern on Glut4 and Leptin genes, and which might be one of the molecular mechanisms for the adiposis development.

Chlorination and chloramination of benzophenone-3 and benzophenone-4 UV filters

The objective of this research was to explore the fundamental reactions between chlorine/chloramine and 2-hydroxyl-4-methoxyl benzophenone (BP3)/2-hydroxyl-4-methoxyl benzophenone-sulfonic acid (BP4), which were the most common reactions in benzophenone-type UV filters during drinking water treatment processes. Both BP3 and BP4 could react with free chlorine and chloramine, with reactions following pseudo-first-order kinetics in excess of chlorine (HClO) and chloramine (NH₂Cl). Generally, chlorination was more rapid than chloramination. BP4 was less reactive than BP3 toward both chlorine and chloramine, due to the presence of an electron-accepting sulfonate group. Therefore, BP3 had a significantly higher disinfection by-products (DBP) formation potential than BP4. Chlorination of BP3 and BP4 generated remarkably higher levels of DBPs than chloramination, with high pH conditions facilitating the formation of chloroform but inhibiting the formation of haloacetic acid (HAAs). Comparison of the reaction behavior of two different BP-type UV filters, i.e., BP3 and BP4, revealed that certain functional groups significantly affected the reactivity of BP-type UV filters in chlorination and chloramination processes. This contribution may provide new insights into the reaction behavior of UV filters during drinking water disinfection process using chlorine and/or chloramine as disinfectant, and provide guidelines for drinking water safety management.

Transformation of antimicrobial agent sulfamethazine by peroxymonosulfate: Radical vs. nonradical mechanisms

Peroxymonosulfate (PMS) is increasingly used as an oxidant for in situ remediation of organic contaminants in soil and groundwater. In this study we demonstrated that sulfamethazine (SMZ) could be transformed by PMS in the absence of any activators. Such transformation was ascribed to the oxidation by PMS per se, rather than free radicals (SO₄^- or HO), superoxide (O₂^-), or singlet oxygen (¹O₂). The aniline moiety of SMZ molecule was the reactive site for PMS oxidation, leading to the formation of nitrated products. This nitration pathway in fact played a significant role in the removal of SMZ in activated PMS oxidation processes. For instance, it contributed 26% of the total SMZ transformation, while SO₄^- contributed the other 74% during the removal of SMZ, in Co(II)/PMS oxidation process with initial PMS and Co(II) concentrations of 1.0 mM and 0.1 μM, respectively. Similar nitration reaction also occurred to other sulfonamide antibiotics bearing an aniline moiety upon the reaction with PMS. Since nitrated sulfonamide antibiotics appear more persistent than the parent compounds and may cause other environmental problems, such a pathway should not be desired. Therefore, PMS might not be an ideal oxidant for the treatment of sulfonamide antibiotics and other compounds having aniline moieties, especially in subsurface remediation practices where efficient activation of PMS represents a major challenge.

Behavior of antibiotic resistance genes under extremely high-level antibiotic selection pressures in pharmaceutical wastewater treatment plants

Pharmaceutical wastewater treatment plants (PWWTPs), which receive wastewater containing extremely high levels of antibiotics, are regarded as potential hot spots for antibiotic-resistance development in the environment. Six sampling campaigns in six PWWTPs in Southeastern China were carried out to assess the prevalence and fate of antibiotic resistance genes (ARGs). Different genes were monitored in different PWWTPs (PWWTP A: lincosamides; PWWTP B: aminoglycosides and macrolides; PWWTP C: quinolones; PWWTP D: macrolides and quinolones; PWWTP E: cephalosporins; and PWWTP F: quinolones and macrolides) using real-time quantitative polymerase chain reactions (PCRs), according to the antibiotic type produced. The levels of typical ARG subtypes in the final effluents ranged from (1.03±0.91)×10¹ to (6.78±0.21)×10⁷copies/mL. The absolute abundance of ARGs in effluents accounted for 0%-577% of influents to the six PWWTPs with a median value of 6%. Most of the ARGs are transported to the dewatered sludge, with concentrations from (1.38±0.21)×10⁵ to (6.84±0.43)×10¹⁰copies/g dry weight (dw). In different treatment units (before/after biological units), a clear trend of proliferation or attenuation was not observed for the ARGs, aside from a strong attenuation in moving bed bio-film reactor (MBBR) in PWWTP C. Through correlation analyses, this study demonstrated that the bacterial abundance and antibiotic concentrations within the PWWTPs influenced the fate of the associated ARGs, and this was possibly related primarily to the intrinsic resistance mechanisms of corresponding ARGs. Macrolide ARGs, which tend to locate in plasmids and transposons, positively correlate weakly with total macrolide antibiotic concentrations but positively correlate strongly with 16S rRNA concentrations. Furthermore, ARG concentrations in the wastewater from fermentation were significantly higher than in the wastewater from chemical synthesis and preparation. This is the first comprehensive study on the behavior of antibiotic resistance genes under extremely high-level antibiotic selection pressures in pharmaceutical wastewater treatment plants (PWWTPs) in Southeastern China.

Comparative study of the formation of brominated disinfection byproducts in UV/persulfate and UV/H2O2 oxidation processes in the presence of bromide

The objective of this research was to compare the transformation of Br^- and formation of brominated byproducts in UV/persulfate (PS) and UV/H₂O₂ processes. It was revealed that Br^- was efficiently transformed to free bromine which reacted with humic acid (HA) or dihydroxybenzoic acid resulting in the formation of brominated byproducts such as bromoacetic acids (BAAs) in UV/PS system. In contrast, no free bromine and brominated byproducts could be detected in UV/H₂O₂ system, although the oxidization of Br^- was evident. We presumed that the oxidation of Br^- by hydroxyl radicals led to the formation of bromine radicals. However, the bromine radical species could be immediately reduced back to Br^- by H₂O₂ before coupling to each other to form free bromine, which explains the undetection of free bromine and BAAs in UV/H₂O₂. In addition to free bromine, we found that the phenolic functionalities in HA molecules, which served as the principal reactive sites for free chlorine attack, could be in situ generated when HA was exposed to free radicals. This study demonstrates that UV/H₂O₂ is more suitable than UV/PS for the treatment of environmental matrices containing Br^-. Graphical abstract Graphical abstract.

Transformation of iodide and formation of iodinated by-products in heat activated persulfate oxidation process

Formation of halogenated disinfection by-products (DBPs) in sulfate radical-based advanced oxidation processes (SR-AOPs) have attracted considerable concerns recently. Previous studies have focused on the formation of chlorinated and brominated DBPs. This research examined the transformation of I^- in heat activated PS oxidation process. Phenol was employed as a model compound to mimic the reactivity of dissolved natural organic matter (NOM) toward halogenation. It was found that I^- was transformed to free iodine which attacked phenol subsequently leading to iodinated DBPs such as iodoform and iodoacetic acids. Iodophenols were detected as the intermediates during the formation of the iodoform and triiodoacetic acid (TIAA). However, diiodoacetic acid (DIAA) was formed almost concomitantly with iodophenols. In addition, the yield of DIAA was significantly higher than that of TIAA, which is distinct from conventional halogenation process. Both the facts suggest that different pathway might be involved during DIAA formation in SR-AOPs. Temperature and persulfate dose were the key factors governing the transformation process. The iodinated by-products can be further degraded by excessive SO₄^- and transformed to iodate. This study elucidated the transformation pathway of I^- in SR-AOPs, which should be taken into consideration when persulfate was applied in environmental matrices containing iodine.

Determination of glyphosate in soil/sludge by high performance liquid chromatography

In order to evaluate the pollution caused due to glyphosate (Glyp) in soils and sludge, it is important to establish a set of standard determination techniques. In this work, the previously reported HPLC analytical method for determination of Glyp has been improved in order to be applied for all kinds of soils/sludge. The soil/sludge samples were extracted using sodium phosphate and trisodium citrate aqueous solutions. The extract was adjusted to pH 9 and contaminations were removed by washing with n-hexane. The method developed in this work further involves derivatization with 9-fluorenylmethylchloroformate (FMOC-Cl) followed by high performance liquid chromatography (HPLC) coupled with fluorescence detection. The method was validated in three soil (red soil, black soil and paddy soil) and two sludge samples (lake and river sludge) from China and verified in six laboratories. A good linear relationship (correlation coefficients ≥0.999) was observed within the range of 0.005-0.5mg/L. The limit of detection (LOD) and the limit of quantitation (LOQ) were determined to be 0.01mg/kg and 0.04mg/kg, respectively. The precision and accuracy were satisfactory with the relative standard deviation (RSD) lower than 15% and the mean recovery values ranging from 75% to 110% (n=6), that spiked at three levels (0.1, 0.5 and 1.0mg/kg).

Bicarbonate-activated persulfate oxidation of acetaminophen

Persulfate (PS) is widely used as an oxidant for in situ chemical remediation of contaminated groundwater. In this study we demonstrated for the first time that PS could be activated by bicarbonate. Acetaminophen was used as the probe compound to examine the reactivity of PS/bicarbonate system. It was found that acetaminophen could be effectively transformed and the reaction rate appeared pseudo-first-order to the concentrations of both acetaminophen and PS. Radical scavenger tests indicated that neither free radicals (SO₄^- and HO) nor superoxide (O₂^-) was responsible for acetaminophen transformation. Generation of singlet oxygen (¹O₂) was verified using furfuryl alcohol (FFA) as a probe. Formation of ¹O₂ was further quantified in D₂O fortified solution based on kinetic solvent isotopic effect (KSIE) but it was found that ¹O₂ contributed only 51.4% of the total FFA transformation. The other 48.6% was presumed to be ascribed to the reaction with peroxymonocarbonate (HCO₄^-). However, the transformation of acetaminophen was mostly due to the reaction with HCO₄^- but not ¹O₂. Instead of degradation, HCO₄^- oxidized acetaminophen via a one-electron abstraction mechanism resulting in the generation of acetaminophen radicals which coupled to each other to form dimers and trimers. HCO₄^- also hydrolyzed rapidly to form hydrogen peroxide (H₂O₂) which led to the formation of ¹O₂, during which O₂^- was a key intermediates. Because bicarbonate is ubiquitously presented in groundwater, the findings of this research provide important insights into the fundamental processes involved in PS oxidation in subsurface.