The degradation of natural organic matters (NOMs) by the combination of UV and chlorine (UV/chlorine) was investigated in this study. UV/chlorine oxidation can effectively degrade NOMs, with the ...degradation of chromophores (∼80%) and fluorophores (76.4–80.8%) being more efficient than that of DOC (15.1–18.6%). This effect was attributed to the chromophores and fluorophores (double bonds, aromatic groups and phenolic groups) being preferentially degraded by UV/chlorine oxidation, particularly reactive groups with high electron donating capacity. Radical species •OH and •Cl were generated during UV/chlorine oxidation, with the contribution of •OH 1.4 times as high as that of •Cl. The degradation kinetics of different molecular weight (MW) fractions suggests that UV/chlorine oxidation degrades high MW fractions into low MW fractions, with the degradation rates of high MW fractions (>3000 Da) 4.5 times of those of medium MW fractions (1000–3000 Da). In comparison with chlorination alone, UV/chlorine oxidation did not increase the formation (30 min) and formation potential (24 h) of trihalomethanes, but instead promoted the formation and formation potential of haloacetic acids and chloral hydrate. Adsorbable organic halogen (AOX) formed from UV/chlorine oxidation of NOM were 0.8 times higher than those formed from chlorination. Cytotoxicity studies indicated that the cytotoxicity of NOM increased after both chlorination and UV/chlorine oxidation, which may be due to the formation of AOX.
•The degradation kinetics of NOM by UV/chlorine was studied.••OH and •Cl contributed for NOM oxidation by UV/chlorine•HPSEC-DOC results revealed the higher reaction rate for high MW than medium MW.•UV/chlorine showed potential risk with forming DPBs and cytotoxicity.
Recent big data analyses have illuminated marine microbial diversity from a global perspective, focusing on planktonic microorganisms. Here, we analyze 2.5 terabases of newly sequenced datasets and ...the Tara Oceans metagenomes to study the diversity of biofilm-forming marine microorganisms. We identify more than 7,300 biofilm-forming 'species' that are undetected in seawater analyses, increasing the known microbial diversity in the oceans by more than 20%, and provide evidence for differentiation across oceanic niches. Generation of a gene distribution profile reveals a functional core across the biofilms, comprised of genes from a variety of microbial phyla that may play roles in stress responses and microbe-microbe interactions. Analysis of 479 genomes reconstructed from the biofilm metagenomes reveals novel biosynthetic gene clusters and CRISPR-Cas systems. Our data highlight the previously underestimated ocean microbial diversity, and allow mining novel microbial lineages and gene resources.
Benzalkonium chlorides (BACs), as typical cationic surfactants and biocides widely applied in household and industrial products, have been frequently detected as micropollutants in many aquatic ...environments. In this study, the combination of UV irradiation and chlorine (UV/chlorine), a newly interested advanced oxidation process, was used to degrade dodecylbenzyldimethylammonium chloride (DDBAC). UV/chlorine showed synergistic effects on DDBAC degradation comparing to UV irradiation or chlorination alone. Radical quenching experiments indicated that degradation of DDBAC by UV/chlorine involved both UV photolysis and radical species oxidation, which accounted for 48.4% and 51.6%, respectively. Chlorine dosage and pH are essential parameters affecting the treatment efficiency of UV/chlorine. The pseudo first order rate constant (kobs, DDBAC) increased from 0.046 min−1 to 0.123 min−1 in response to chlorine dosage at 0–150 mg/L, and the degradation percentage of DDBAC within 12 min decreased from 81.4% to 56.6% at pH 3.6–9.5. Five main intermediates were identified and semi-quantified using HPLC-MS/MS and a possible degradation pathway was proposed. The degradation mechanisms of DDBAC by UV/chlorine included cleavage of the benzyl-nitrogen bond and hydrogen abstraction of the alkyl chain. Trichloromethane (TCM), chloral hydrate (CH), trichloropropanone (TCP), dichloropropanone (DCP) and dichloroacetonitrile (DCAN) were detected using GC-ECD. The formation of chlorinated products increased rapidly initially, then decreased (TCM, TCP, DCP and DCAN) or remained stable (CH) with extended treatment. The actual formation of TCM peaked at 30 min (50.3 μg/L), while other chlorinated products did not exceed 10 μg/L throughout the process. Based on the luminescent bacterial assay, DDBAC solution underwent almost complete detoxification subjected to UV/chlorine treatment for 120 min, which is more effective than UV irradiation or chlorination alone.
•UV/chlorine showed synergistic degradation of DDBAC than UV and chlorination.•DDBAC degraded through both UV photolysis and radicals oxidation during UV/chlorine.•Degradation pathway of DDBAC during UV/chlorine oxidation was proposed.•Formation of chlorinated products decreased with extended UV/chlorine oxidation.•UV/chlorine oxidation was efficient at DDBAC detoxification.
The worldwide prevalence of infections caused by antibiotic-resistant Gram-negative bacteria poses a serious threat to public health due to the limited therapeutic alternatives. Cationic peptides ...represent a large family of antibiotics and have attracted interest due to their diverse chemical structures and potential for combating drug-resistant Gram-negative pathogens. Here, we analyze 7395 bacterial genomes to investigate their capacity for biosynthesis of cationic nonribosomal peptides with activity against Gram-negative bacteria. Applying this approach, we identify two novel compounds (brevicidine and laterocidine) showing bactericidal activities against antibiotic-resistant Gram-negative pathogens, such as Pseudomonas aeruginosa and colistin-resistant Escherichia coli, and an apparently low risk of resistance. The two peptides show efficacy against E. coli in a mouse thigh infection model. These findings may contribute to the discovery and development of Gram-negative antibiotics.
Two large low velocity provinces (LLVPs) are observed in Earth's lower mantle, beneath Africa and the Pacific Ocean, respectively. The maximum height of the African LLVP is ∼1,000 km larger than that ...of the Pacific LLVP, but what causes this height difference remains unclear. LLVPs are often interpreted as thermochemical piles whose morphology is greatly controlled by the surrounding mantle flow. Seismic observations have revealed that while some subducted slabs are laterally deflected at ∼660–1,200 km, other slabs penetrate into the lowermost mantle. Here, through geodynamic modeling experiments, we show that rapid sinking of stagnant slabs to the lowermost mantle can cause significant height increases of nearby thermochemical piles. Our results suggest that the African LLVP may have been pushed more strongly and longer by surrounding mantle flows to reach a much shallower depth than the Pacific LLVP, perhaps since the Tethys slabs sank to the lowermost mantle.
Plain Language Summary
Seismic observations have revealed the two large low velocity provinces (LLVPs) beneath Africa and the Pacific Ocean in Earth's lowest mantle. Growing evidence indicates that the maximum height of the African LLVP is up to ∼1,000 km taller than that of the Pacific LLVP, but the underlying cause of such a large difference in height remains uncertain. Geodynamic modeling studies have shown that the morphology of LLVPs is greatly controlled by their interactions with surrounding mantle flow which is mainly driven by subduction of cold slabs. Seismic observations have shown that while some subducted slabs flatten or stagnate at ∼660–1,200 km, other slabs arrive at the deepest mantle. With geodynamic modeling experiments, we show that catastrophic sinking of subducted slabs into the lower mantle can cause strong upwelling flows that in turn greatly increase the height of nearby LLVP‐like piles, while other piles can be less affected. This work suggests that the African LLVP may be enduring stronger nearby mantle flow to rise by the slab‐driven surrounding mantle flow than the Pacific LLVP. The African LLVP may start rising since the sinking of the Tethys slabs to the lowermost mantle.
Key Points
Continuous sinking of voluminous subducted slabs to the lower mantle can push nearby large low velocity province (LLVP)‐like piles to rise significantly
Episodic large increase of height is only possible for piles that are nearly neutrally buoyant and are relatively unstable
The African LLVP may have been strongly pushed by the Tethys slabs and reach a much larger height than the Pacific LLVP
UV based advanced oxidation processes (UV-AOPs) that efficiently eliminate organic pollutants during water treatment have been the subject of numerous investigations. Most organic pollutants are not ...completely mineralized during UV-AOPs but are partially oxidized into transformation products (TPs), thereby adding complexity to the treated water and posing risks to humans, ecological systems, and the environment. While the degradation kinetics and mechanisms of pollutants have been widely documented, there is little information about the risks associated with TPs. In this review, we have collated recent knowledge about the harmful TPs that are generated in UV/H2O2 and UV photocatalysis, two UV-AOPs that have been studied extensively. Toxic and assimilable TPs were ubiquitously observed in more than 80% of UV-AOPs of organic pollutants, of which the toxicity and assimilability levels changed with variations in the reaction conditions, such as the UV fluence and oxidant dosage. Previous studies and modeling assessments showed that toxic and assimilable TPs may be generated during hydroxylation, dealkylation, decarboxylation, and deamination. Among various reactions, TPs generated from dealkylation and decarboxylation were generally less and more toxic than the parent pollutants, respectively; TPs generated from decarboxylation and deamination were generally less and more assimilable than the parent pollutants, respectively. There is also potential concern about the sensory-unpleasant TPs generated by oxidations and subsequent metabolism of microorganisms. In this overview, we stress the need to include both the concentrations of organic pollutants and the evaluations of the risks from TPs for the quality assessments of the water treated by UV-AOPs.
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•The risk posed by toxic, assimilable, and sensory-unpleasant TPs is pronounced.•The quantitative levels of the toxicity and assimilability of TPs are surveyed.•Reactions generating toxic and assimilable TPs are surveyed and models assessed.•The influencing factors on the generation of TPs suggests optimizations are need.•Sensory-unpleasant TPs are potential concerns in UV photochemical oxidation.
An ultraviolet (UV)-based advanced oxidation process (AOP) for disinfecting water is introduced in this paper. This study aimed to evaluate the potential of UV light-emitting diodes ...(UV-LEDs)/chlorine AOP (UV/Cl2) for Bacillus subtilis spore inactivation. Chlorine was combined with 265 and 280 nm LEDs (UV265/Cl2, UV280/Cl2) and investigated. The addition of 4.0 mg/L of free chlorine at pH 7.0 in the presence of 125 mJ/cm2 of UV irradiation resulted in an additional 1.8-log reduction in UV265/Cl2 and 1.5-log reduction in UV280/Cl2. There was no observed enhancement in spore inactivation with the addition of a radical scavenger, t-BuOH, which indicated the role of •OH in the synergistic effect. To quantitatively evaluate the synergism, the primary treatment with UV/Cl2 was followed by further UV or Cl2 treatment. After UV/Cl2 pretreatment at different pH levels, the 265 and 280 nm LEDs treatment enhanced an approximate 0.4–0.5-log reduction compared to UV only, and Cl2 treatment enhanced an approximate 0.7–1.1-log reduction compared to Cl2 only. In addition, at pH 7.0, in UV265/Cl2-Cl2 and UV280/Cl2-Cl2, the inactivation rate constant k increased by approximately 2 and 1.5 times, respectively. The CT for the lag phases (CTlag) reduced to approximately 67 and 58%, respectively. Similar results were obtained at pH 7.5 and 8.0, and in the secondary effluent. The synergistic effect on spore inactivation suggested that the pathogen inactivation efficiency of sequential UV and chlorine disinfection processes, which are commonly applied, can be significantly enhanced by adding chlorine prior to UV treatment.
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•The combined UV-LEDs and chlorine systems on B. subtilis spore inactivation were evaluated.•Significant enhanced spore inactivation were obtained in the combined systems.•Role of hydroxyl radical formed from chlorine photolysis was investigated.•UV-LEDs and chlorine disinfection were both accelerated after combined system treatment.
The high-valent cobalt-oxo species (Co(IV)=O) is being increasingly investigated for water purification because of its high redox potential, long half-life, and antiinterference properties. However, ...generation of Co(IV)=O is inefficient and unsustainable. Here, a cobalt-single-atom catalyst with N/O dual coordination was synthesized by O-doping engineering. The O-doped catalyst (Co-OCN) greatly activated peroxymonosulfate (PMS) and achieved a pollutant degradation kinetic constant of 73.12 min
g
, which was 4.9 times higher than that of Co-CN (catalyst without O-doping) and higher than those of most reported single-atom catalytic PMS systems. Co-OCN/PMS realized Co(IV)=O dominant oxidation of pollutants by increasing the steady-state concentration of Co(IV)=O (1.03 × 10
M) by 5.9 times compared with Co-CN/PMS. A competitive kinetics calculation showed that the oxidation contribution of Co(IV)=O to micropollutant degradation was 97.5% during the Co-OCN/PMS process. Density functional theory calculations showed that O-doping influenced the charge density (increased the Bader charge transfer from 0.68 to 0.85 e), optimized the electron distribution of the Co center (increased the d-band center from -1.14 to -1.06 eV), enhanced the PMS adsorption energy from -2.46 to -3.03 eV, and lowered the energy barrier for generation of the key reaction intermediate (*O*H
O) during Co(IV)=O formation from 1.12 to 0.98 eV. The Co-OCN catalyst was fabricated on carbon felt for a flow-through device, which achieved continuous and efficient removal of micropollutants (degradation efficiency of >85% after 36 h operation). This study provides a new protocol for PMS activation and pollutant elimination through single-atom catalyst heteroatom-doping and high-valent metal-oxo formation during water purification.
Ozonation is widely used in wastewater treatment but the associated byproduct formation is a concern. When ozonation is used in the presence of bromide, bromate is generally considered as a major ...byproduct, and few studies have examined the toxicity of organic byproducts. This study was designed to investigate the cytotoxicity, genotoxicity and DNA/RNA oxidative damage to Chinese hamster ovary (CHO) cells of organic extracts from ozonated wastewater in the absence or presence of bromide. Ozonation effectively detoxified secondary effluents containing no bromide. However, ozonation significantly increased the cytotoxicity and genotoxicity of the effluents spiked with a bromide concentration as low as 100 μg/L, compared with the bromide-free effluent. When the bromide concentration in the effluent was increased to 2000 μg/L, ozonation resulted in 1.4–1.5 times the cytotoxicity and 1.5–5.0 times the genotoxicity of the non-ozonated secondary effluent. Besides, the oxidative stress (including reactive oxygen species and reactive nitrogen species) and DNA/RNA oxidative damage also became more severe and a high level of 8-hydroxy-(deoxy)guanosine was detected in the CHO cell nucleus in the presence of bromide. Cytotoxicity and genotoxicity were found to increase with the formation of total organic bromine (TOBr). When the CHO cells were exposed to both the organic byproducts and bromate formed from wastewater containing 500 and 2000 μg/L bromide, bromate significantly increased oxidative stress and DNA/RNA oxidative damage at relatively high concentration factors, suggesting both organic byproduct and bromate can contribute to toxicity increase. During ozonation of the effluent containing bromide, particular attention should be paid to the organic byproducts such as TOBr.
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•Ozonation reduced the toxicity of organics in wastewater containing no Br-.•Toxicity of organics in ozonated wastewater with 100 μg/L Br− was higher than that without Br-.•Cytotoxicity and genotoxicity was increased with the TOBr formation.•Both organic byproducts and bromate can contribute to toxicity increase.
Background
This study aims to analyze breast cancer burden attributable to high body mass index (BMI) and high fasting plasma glucose (FPG) in China from 1990 to 2019.
Methods
Data were obtained ...from the Global Burden of Disease (GBD) study 2019. Deaths and disability‐adjusted life years (DALYs) were used for attributable burden, and age‐period‐cohort (APC) model was used to evaluate the independent effects of age, period and birth cohort.
Results
In 2019, the age‐standardized mortality and DALY rates of breast cancer attributable to high BMI were 1.107 (95% UI: 0.311, 2.327) and 29.990 (8.384, 60.713) per 100 000, and mortality and DALY rates attributable to high FPG were 0.519 (0.095, 1.226) and 13.662 (2.482, 32.425) per 100 000. From 1990 to 2019, the age‐standardized mortality and DALY rates of breast cancer attributable to high BMI increased by 1.192% and 1.180%, and the trends of high FPG were not statistically significant. The APC results showed that the age effects of high BMI and high FPG‐mortality and DALY rates increased, with the highest rates in the age group over 80 years. The birth cohort effects of high BMI showed “inverted V” shapes, while high FPG showed downward trends.
Conclusions
Age was the main reason for the increase of attributable burden, and postmenopausal women were the high‐risk groups. Therefore, targeted prevention measures should be developed to improve postmenopausal women's awareness and effectively reduce the prevalence of obesity and diabetes, thereby reducing the breast cancer burden caused by metabolic factors in China.
Breast cancer burden caused by metabolic factors remains a serious health challenge among Chinese women, with the deaths and DALYs attributed to high BMI and high FPG showing significant upward trends over the past 30 years. Age was the main reason for the increase of attributable burden. Postmenopausal women might be the high‐risk groups, and the earlier birth cohorts were vulnerable groups for the development of breast cancer.
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