Application of molecular epidemiology in revealing HIV-1 transmission network and recombination patterns in Tianjin, China.

Using a comprehensive molecular epidemiological approach, we characterized the transmission dynamics of HIV-1 among the MSM population in Tianjin, China. Our findings revealed that 38.56% (386/1001) of individuals clustered across 109 molecular transmission clusters (TCs), with MSM aged 50 and below being the group most commonly transmitting HIV-1. Among the identified TCs, CRF01_AE predominated, followed by CRF07_BC. Notably, CRF07_BC demonstrated a higher propensity for forming large clusters compared to CRF01_AE. Birth-death skyline analyses of the two largest clusters indicated that the HIV/AIDS transmission may be at a critical point, nearly all had Re approximately 1 by now. A retrospective analysis revealed that the rapid expansion of these large clusters was primarily driven by the introduction of viruses in 2021, highlighting the crucial importance of continuous molecular surveillance in identifying newly emerging high-risk transmission chains and adapting measures to address evolving epidemic dynamics. Furthermore, we detected the transmission of drug-resistant mutations (DRMs) within the TCs, particularly in the CRF07_BC clusters (K103N, Y181C, and K101E) and CRF01_AE clusters (P225H and K219R), emphasizing the importance of monitoring to support the continued efficacy of first-line therapies and pre-exposure prophylaxis (PrEP). Recombination analyses indicated that complex recombinant patterns, associated with increased amino acid variability, could confer adaptive traits to the viruses, potentially providing a competitive advantage in certain host populations or regions. Our study highlights the potential of integrating molecular epidemiological and phylodynamic approaches to inform targeted interventions.

Selective Oxidation of Triethylamine Catalyzed by Mn-Ce/ZSM-5.

The selective catalytic oxidation (SCO) of triethylamine (TEA) to harmless nitrogen (N2), carbon dioxide (CO2), and water (H2O) is of green elimination technology. In this paper, Mn-Ce/ZSM-5 with different proportions of MnOx/CeOx were studied for the selective catalytic combustion of TEA. The catalysts were characterized by XRD, BET, H2-TPR, XPS, and NH3-TPD and their catalytic activities were analyzed. The results showed that MnOx was the main active component. The addition of a small amount of CeOx promotes the generation of high-valence Mn ions, which reduces the reduction temperature of the catalyst and increases the redox capacity of the catalyst. In addition, the synergistic effect between CeOx and MnOx significantly improves the mobility of reactive oxygen species on the catalyst, thus improving the catalytic performance of the catalyst. The catalytic oxidation performance of TEA over 15Mn5Ce/ZSM-5 is the highest. TEA can be completely converted at 220 °C, and the selectivity for N2 is up to 80%. The reaction mechanism was studied by in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS).

Use of magnetic powder to effectively improve the denitrification employing the activated sludge fermentation liquid as carbon source.

Nitrogen removal is often limited in municipal wastewater treatment due to the lack of sufficient carbon source. Utilizing volatile fatty acids (VFAs) from waste activated sludge (WAS) fermentation broth as a carbon source is an ideal alternative to reduce the cost for wastewater treatment plants (WWTPs) and improve denitrification efficiency simultaneously. In this study, an anaerobic system was applied for simultaneous denitrification and WAS fermentation and the addition of magnetic microparticles (MMP) were confirmed to enhance both denitrification and WAS fermentation. Firstly, the addition of MMP increased the nitrate reduction rate by over 25.36% and improve the production of N2. Additionally, the equivalent chemical oxygen demand (COD) of the detected VFAs increased by 7.06%-14.53%, suggesting that MMP promoted the WAS fermentation. The electron transfer efficiency of denitrifies was accelerated by MMP via electron-transporting system (ETS) activity and cyclic voltammetry (CV) experiments, which might result in the promotional denitrification and WAS fermentation performance. Furthermore, the high-throughput sequencing displayed that, MMP enriched key microbes capable of degrading the complex organics (Chloroflexi, Synergistota and Spirochaetota) as well as the typical denitrifies (Bacteroidetes_vadinHA17 and Denitratisoma). Therefore, this study provides a novel strategy to realize simultaneous WAS utilization and denitrification for WWTPs.

[Influence of bronchopulmonary dysplasia on cerebral blood flow in preterm infants: a prospective study based on arterial spin labeling]. / åŸºäºŽåŠ¨è„‰è‡ªæ—‹æ ‡è®°æˆåƒæŠ€æœ¯æŽ¢è®¨æ”¯æ°”ç®¡è‚ºå‘è‚²ä¸è‰¯å¯¹æ—©äº§å„¿è„‘è¡€æµé‡å½±å“çš„å‰çž»æ€§ç ”ç©¶.

OBJECTIVES: To investigate local cerebral blood perfusion in preterm infants with bronchopulmonary dysplasia (BPD) based on cerebral blood flow (CBF) values of arterial spin labeling (ASL). METHODS: A prospective study was conducted on 90 preterm infants with a gestational age of <32 weeks and a birth weight of <1 500 g who were born in the Department of Obstetrics and admitted to the Department of Neonatology in the Third Affiliated Hospital of Zhengzhou University from August 2021 to June 2022. All of the infants underwent cranial MRI and ASL at the corrected gestational age of 35-40 weeks. According to the presence or absence of BPD, they were divided into a BPD group with 45 infants and a non-BPD group with 45 infants. The two groups were compared in terms of the CBF values of the same regions of interest (frontal lobe, temporal lobe, parietal lobe, occipital lobe, thalamus, and basal ganglia) on ASL image. RESULTS: Compared with the non-BPD group, the BPD group had a significantly lower 1-minute Apgar score, a significantly longer duration of assisted ventilation, and a significantly higher incidence rate of fetal distress (P<0.05). After control for the confounding factors such as corrected age and age at the time of cranial MRI by multiple linear regression analysis, compared with the non-BPD group, the BPD group still had higher CBF values of the frontal lobe, temporal lobe, parietal lobe, occipital lobe, basal ganglia, and thalamus at both sides (P<0.05). CONCLUSIONS: BPD can increase cerebral blood perfusion in preterm infants, which might be associated with hypoxia and a long duration of assisted ventilation in the early stage.

Integration of Highly Luminescent Lead Halide Perovskite Nanocrystals on Transparent Lead Halide Nanowire Waveguides through Morphological Transformation and Spontaneous Growth in Water.

The integration of highly luminescent CsPbBr3 quantum dots on nanowire waveguides has enormous potential applications in nanophotonics, optical sensing, and quantum communications. On the other hand, CsPb2 Br5 nanowires have also attracted a lot of attention due to their unique water stability and controversial luminescent property. Here, the growth of CsPbBr3 nanocrystals on CsPb2 Br5 nanowires is reported first by simply immersing CsPbBr3 powder into pure water, CsPbBr3- γ Xγ (X = Cl, I) nanocrystals on CsPb2 Br5 -γ Xγ nanowires are then synthesized for tunable light sources. Systematic structure and morphology studies, including in situ monitoring, reveal that CsPbBr3 powder is first converted to CsPb2 Br5 microplatelets in water, followed by morphological transformation from CsPb2 Br5 microplatelets to nanowires, which is a kinetic dissolution-recrystallization process controlled by electrolytic dissociation and supersaturation of CsPb2 Br5 . CsPbBr3 nanocrystals are spontaneously formed on CsPb2 Br5 nanowires when nanowires are collected from the aqueous solution. Raman spectroscopy, combined photoluminescence, and SEM imaging confirm that the bright emission originates from CsPbBr3 -γ Xγ nanocrystals while CsPb2 Br5 -γ Xγ nanowires are transparent waveguides. The intimate integration of nanoscale light sources with a nanowire waveguide is demonstrated through the observation of the wave guiding of light from nanocrystals and Fabry-Perot interference modes of the nanowire cavity.

Enhanced removal of cadmium from wastewater with coupled biochar and Bacillus subtilis.

Shortcomings of individual biochar or microbial technologies often exist in heavy metal removal from wastewater and may be circumvented by coupled use of biochar and microorganisms. In this study, Bacillus subtilis and each of three biochars of different origins (corn stalk, peanut shell, and pine wood) were coupled forming composite systems to treat a cadmium (Cd, 50 mg/L) wastewater formulated with CdCl2 in batch tests. Biochar in composite system enhanced the activity and Cd adsorption of B. subtilis. Compared with single systems with Cd removal up to 33%, the composite system with corn stalk biochar showed up to 62% Cd removal, which was greater than the sum of respective single B. subtilis and biochar systems. Further analysis showed that the removal of Cd by the corn stalk composite system could be considered to consist of three successive stages, that is, the biochar-dominant adsorption stage, the B. subtilis-dominant adsorption stage, and the final biofilm formation stage. The final stage may have provided the composite system with the ability to achieve prolonged steady removal of Cd. The biochar-microorganism composite system shows a promising application for heavy metal wastewater treatment.

Construction of early risk prediction models for bronchopulmonary dysplasia in preterm infants. / 早产儿支气管肺发育不良早期风险预测模型的构建.

OBJECTIVES: To construct risk prediction models for bronchopulmonary dysplasia (BPD) in preterm infants on postnatal days 3, 7, and 14. METHODS: A retrospective analysis was performed on the medical data of 414 preterm infants, with a gestational age of <32 weeks and a birth weight (BW) of <1 500 g, who were admitted to the neonatal intensive care unit from July 2019 to April 2021. According to the diagnostic criteria for BPD revised in 2018, they were divided into a BPD group with 98 infants and a non-BPD group with 316 infants. The two groups were compared in terms of general status, laboratory examination results, treatment, and complications. The logistic regression model was used to identify the variables associated with BPD. The receiver operating characteristic (ROC) curve was used to evaluate the predictive value of models. RESULTS: The logistic regression analysis showed that BW, asphyxia, grade III-IV respiratory distress syndrome (RDS), acute chorioamnionitis, interstitial pneumonia, fraction of inspired oxygen (FiO2), and respiratory support mode were the main risk factors for BPD (P<0.05). The prediction models on postnatal days 7 and 14 were established as logit (P7) =-2.049-0.004×BW (g) +0.686×asphyxia (no=0, yes=1) +1.842×grade III-IV RDS (no=0, yes=1) +0.906×acute chorioamnionitis (no=0, yes=1) +0.506×interstitial pneumonia (no=0, yes=1) +0.116×FiO2 (%) +0.816×respiratory support mode (no=0, nasal tube=1, nasal continuous positive airway pressure=2, conventional mechanical ventilation=3, high-frequency mechanical ventilation=4) and logit (P14) =-1.200-0.004×BW (g) +0.723×asphyxia+2.081×grade III-IV RDS+0.799×acute chorioamnionitis+0.601×interstitial pneumonia+0.074×FiO2 (%) +0.800×respiratory support mode, with an area under the ROC curve (AUC) of 0.876 and 0.880, respectively, which was significantly larger than the AUC of the prediction model on postnatal day 3 (P<0.05). CONCLUSIONS: BW, asphyxia, grade III-IV RDS, acute chorioamnionitis, interstitial pneumonia, FiO2, and respiratory support mode are the main risk factors for BPD and can be used to construct risk prediction models. The prediction models on postnatal days 7 and 14 can effectively predict BPD.

The assessment of forest ecological security and its determining indicators: A case study of the Yangtze River Economic Belt in China.

This study put forward an evaluation index system for measuring forest ecological security index (FESI). Taking the 1086 counties located in the Yangtze River Economic Belt as a case study, we investigated the change and its spatial pattern of FESI, as well as the determining indicators (both natural and socio-economic), with the support of Arcmap and GeoDA software. The average FESI value of the study counties in 2010 and 2015 was found to be 0.4226 and 0.4990, increased by 18.08%. Spatially, an evident spatial gradient change was identified, with FESI values in the upstream areas of the Yangtze River being higher than those in midstream areas, and the values of midstream areas in turn being higher than those in downstream areas. The eight tributary basins within the economic belt witnessed significantly different FESI values. Based on the results of this evaluation of FESI and its sub-evaluation indexes, we identified 46.04% of the total counties as constituting "problem areas". These problem areas were mainly concentrated in Shanghai, Jiangsu and Anhui provinces, followed by counties around Dongting Lake, Poyang Lake and in Sichuan province. A regression analysis was conducted in order to identify the determining indicators behind forest ecological security, with results indicating that the ratio of secondary industry, the urbanization rate, the per capita financial institution loan balance, accumulated temperature and wind speed all negatively impacted on FESI values, while population structure, soil organic matter and rainfall were revealed to play a positive role; all of these indicators were highly significant. Given these findings, we also set out a series of policy measures intended to promote the sustainable forest development of the study region. These include the vigorous development of tertiary industry and moves to reduce the proportion of the secondary industry in the national economy, the development of a circular economy, slowing the pace of urbanization, and continued increases in forestry investment in central cities - particularly in problem areas.

Phosphate Changes Effect of Humic Acids on TiO2 Photocatalysis: From Inhibition to Mitigation of Electron-Hole Recombination.

A major challenge for photocatalytic water purification with TiO2 is the strong inhibitory effect of natural organic matter (NOM), which can scavenge photogenerated holes and radicals and occlude ROS generation sites upon adsorption. This study shows that phosphate counteracts the inhibitory effect of humic acids (HA) by decreasing HA adsorption and mitigating electron-hole recombination. As a measure of the inhibitory effect of HA, the ratios of first-order reaction rate constants between photocatalytic phenol degradation in the absence versus presence of HA were calculated. This ratio was very high, up to 5.72 at 30 mg/L HA and pH 4.8 without phosphate, but was decreased to 0.76 (5 mg/L HA, pH 8.4) with 2 mM phosphate. The latter ratio indicates a surprising favorable effect of HA on TiO2 photocatalysis. FTIR analyses suggest that this favorable effect is likely due to a change in the conformation of adsorbed HA, from a multiligand exchange arrangement to a complexation predominantly between COOH groups in HA and the TiO2 surface in the presence of phosphate. This configuration can reduce hole consumption and facilitate electron transfer to O2 by the adsorbed HA (indicated by linear sweep voltammetry), which mitigates electron-hole recombination and enhances contaminant degradation. A decrease in HA surface adsorption and hole scavenging (the predominant inhibitory mechanisms of HA) by phosphate (2 mM) was indicated by a 50% decrease in the photocatalytic degradation rate of HA and 80% decrease in the decay rate coefficient of interfacial-related photooxidation in photocurrent transients. These results, which were validated with other compounds (FFA and cimetidine), indicate that anchoring phosphate - or anions that exert similar effects on the TiO2 surface - might be a feasible strategy to counteract the inhibitory effect of NOM during photocatalytic water treatment.

[Isolation and identification of berberine from endophytic fungi HL-Y-3].

The endophytic fungi HL-Y-3, which was isolated from the healthy leaves of Coptis chinensis, produced berberine when grown in the PDA culture medium. The presence of berberine was confirmed by the chromatographic and spectroscopic analyses. The yield of berberine was recorded as 9.313 µg•g⁻¹ by HPLC. The strain HL-Y-3 was identified as Alternaria sp.by morphological observation and 5.8S rDNA-ITS sequence analysis.The separation and purification of constituents were performed by PTLC. The mass spectrometry (MS) of the analyte was shown to be identical with authentic berberine.Further analysis with nuclear magnetic resonance (NMR) spectroscopy to showed that the chemical structure of the fungal berberine was identical with authentic berberine. The research provided new resources for the utilization of berberine.

[Effect of Naoshuantong capsule on change of SSQOL index in patients with ischemic stroke in six mouths follow-up].

To evaluate the effect of Naoshuantong capsule on the life quality of patients with ischemic stroke in six months of follow-up studies, and observe the adverse events. The results would provide reference for the secondary prevention on the recovery stage of ischemic stroke. 696 patients from 12 Class III Grade I hospitals nationwide were divided into 2 groups by central randomization system. The study group, 344 cases, were treated with Naoshuantong capsule plus Aspirin, and the control group, 352 cases, were treated with Aspirin. The patients were treated for 6 months. At the end of treatment, SS-QOL used for evaluating the quality of life was observed. The safety index was defined by adverse observation event. The incidence of adverse events and laboratory tests results were observed before and after treatment at the same time. The results indicated that compared to the control group, the treatment group had significant statistical difference in the impact of effort, self-care ability and the the work or labor ability of patients (P < 0.05). No serious adverse events were observed. Naoshuantong capsule showed some superiority to Asprin on improving the quality of life on patients with ischemic stroke, and it could be used in secondary prevention on the recovery stage of ischemic stroke. Naoshuantong capsule is safe and effective in the treatment of convalescence ischemic stroke.

Ultrasound-enhanced and microwave-assisted extraction of lipid from Dunaliella tertiolecta and fatty acid profile analysis.

Microalgal lipid is considered as a potential biodiesel resource due to its advantages compared to other bioresources. The production of biofuel from microalgae includes several stages like microalgae cultivation, biomass harvest, biomass treatment, lipid extraction, and the ultimate biodiesel synthesis. Lipid extraction is closely associated with the productivity and cost of energy production. In the present study, lipid of green algae Dunaliella tertiolecta was extracted by chemical agents with involvement of ultrasound and microwave. The optimization of experimental conditions was carried out by response surface methodology and orthogonal test design. Using the ultrasonic technique, an extraction rate of 45.94% was obtained under the optimum conditions of ultrasonic power 370 W, extraction time 5 min and liquid/solid ratio 125 mL/g. The extraction rate of 57.02% was obtained by the means of microwave assistance under the optimized conditions of extraction time 160 s, microwave power 490 W and liquid/solid ratio 100 mL/g. The comparison of the two results indicated microwave was more effective than ultrasound in extracting process. When the two techniques were utilized in combination, the optimized condition was ultrasonic power 320 W, ultrasonic time 4 min, microwave power 280 W, microwave time 120 s and liquid/solid ratio 100 mL/g, and the extraction rate was 49.97%.

Exposing image forgery by detecting consistency of shadow.

We propose two tampered image detection methods based on consistency of shadow. The first method is based on texture consistency of shadow for the first kind of splicing image, in which the shadow as well as main body is copied and pasted from another image. The suspicious region including shadow and nonshadow is first selected. Then texture features of the shadow region and the nonshadow region are extracted. Last, correlation function is used to measure the similarity of the two texture features. By comparing the similarity, we can judge whether the image is tampered. Due to the failure in detecting the second kind of splicing image, in which main body, its shadow, and surrounding regions are copied and pasted from another image, another method based on strength of light source of shadows is proposed. The two suspicious shadow regions are first selected. Then an efficient method is used to estimate the strength of light source of shadow. Last, the similarity of strength of light source of two shadows is measured by correlation function. By combining the two methods, we can detect forged image with shadows. Experimental results demonstrate that the proposed methods are effective despite using simplified model compared with the existing methods.

Enhancement of livestock wastewater treatment by a novel wooden-modified biocarrier.

Intensive livestock wastewater poses threat to ecosystem. A novel wooden-modified biocarrier was applied in this study to enhance the livestock wastewater treatment in anoxic-aerobic systems. Compared to the ordinary polyethylene (PE) biocarrier, the novel wooden-modified biocarrier improved the biomass owing to its rough surface and porous side wall, and had better nitrogen removal ability. The biomass of wooden-modified biocarrier was 6.3 ± 1.1 and 36.4 ± 17.0 times that of PE biocarrier in anoxic and aerobic condition, respectively. The removal rates of ammonia nitrogen and total nitrogen of this novel biocarrier on specific biofilm's aera eventually stabilized at 0.64 ± 0.10 and 0.94 ± 0.21 g N/m2/d, respectively. Notably, this wooden-modified biocarrier was conducive to increase nitrogen removal by simultaneous nitrification and denitrification to some extent. The biofilm on novel modified biocarrier had higher extracellular polymeric substances (EPS) contents than activated sludge (AS), and the proportions of polysaccharides (PS) in EPS from biocarrier were more than those from AS. Compared to PE biocarrier and AS, the wooden-modified biocarriers enhanced the enrichment of nitrifying and denitrifying bacteria, and promoted the membrane transport and aerobic nitrogen metabolism. This study confirmed the superiority of wooden-modified biocarrier and provided reference for the treatment of high concentration sewage in full-scale project.

Novel flocking materials as biocarriers in moving bed biofilm reactor for improving simultaneous nitrification and denitrification performance.

Biocarrier is the key factor for the stable operation of moving bed biofilm reactor (MBBR). To achieve efficient simultaneous nitrification and denitrification (SND), this study provided novel flocking materials as biocarriers. The biofilm formation experiment showed that longer flocking carrier was more conducive to biomass accumulation, resulting in greater oxygen uptake rate. The continuous operation results showed that the total nitrogen removal and SND performance of the MBBR with the addition of 5.0 mm flocking carriers reached 52.0 % and 70.5 %, respectively, which were 29.1 % and 33.3 % greater than those of the control. Compared with those in suspended sludge, the extracellular polymeric substances and protein components in the biocarrier were more abundant. Furthermore, the relative abundance of genera related to denitrification and the nitrogen metabolic sequence improved with the addition of the novel flocking biocarriers. This study demonstrated the effectiveness of novel flocking fillers in improving the performance of MBBR.

Virtual group photography based on scene and person perception.

Group photos have become indispensable in various gathering scenarios, such as family reunions, friends' gatherings, competitions, conferences, store openings, and school graduation ceremonies. The researchers tried automatically adding people who could not participate in the group photo. However, the current research on generating the pose or position of the person by context prediction of the group photo ignores the individual attributes (such as height and body shape) of the target person and does not consider the pose and boundary of the person at the same time. To address these issues, we propose a virtual group photography model that combines the global context of a group photo and the individual attributes of the target person. The model is divided into two stages. The first stage is to predict the person's position, pose, and boundary in the new group photo based on the context of the input group photo and the person's characteristics. The second stage generates new group photos based on the first stage's pose and boundary results. The experimental results show that our method can significantly improve the harmony and authenticity of the synthesis of people in group photos and synthesize the characters that should exist in the group photo, which is very suitable for the field of group photos.

Simultaneous denitrification enhancement and sludge reduction based on novel suspended carrier modified using activated carbon and magnetite at low carbon/nitrogen ratio.

A novel suspended carrier was prepared by sticking activated carbon (AC) and magnetite (Fe3O4) onto polypropylene slices. Although this carrier could not reverse the decreased denitrification capacity trends under anoxic conditions at an influent carbon/nitrogen (C/N) ratio of 2, it enhanced denitrification by stimulating sludge reduction and accelerating electron transfer to certain extent. The carrier stuck by mixed AC/Fe3O4 exhibited better performance in terms of sludge reduction, extracellular polymeric substances (EPS) secretion, and denitrification than that merely stuck by AC and Fe3O4 at an influent C/N ratio of 2. The carrier stuck by mixed AC/Fe3O4 increased the total nitrogen removal efficiency by 24.6 % ± 12.5 % in a 72-h denitrification batch experiment compared to the common polypropylene carrier. Moreover, the carrier improved EPS secretion and nitrogen metabolism and promoted the growth of Trichococcus and some denitrifying genera. This study provides a reference for the treatment of low C/N ratio sewage.

Contextual Relevance of Sustainable Supply Chain: Recycling, Philanthropy, or Both?

Many firms have already been actively or passively involved in sustainable supply chain management with the objective of improving the triple bottom line (TBL). But whether the limited funds should be allocated to both community responsibility activities (e.g., corporate philanthropy) and environmental protection activities (e.g., recycling) is a confusing question. This paper provides deep insights into the combination strategy of two corporate social responsibility (CSR) types in a two-tier sustainable supply chain by modeling analysis. The decision models in eight scenarios with different combinations of CSR types are proposed and applied for the determination of equilibrium scenarios. The paper's findings highlight: under certain conditions, (1) the supply chain with two types of CSR is the equilibrium scenario and improves the TBL; (2) counter-intuitively, balancing short- and long-term benefits, firms are more willing to cooperate with partners with relatively low consumers sensitivity of CSR activities; (3) it is wise for the manufacturer to allocate more funding to environmental responsibility than to community responsibility. In addition, considering both short- and long-term benefits, comparing with the manufacturer, the retailer has a stronger incentive to improve recycling efficiency.

The relationship between zooplankton vertical distribution and the concentration of aqueous Hg in boreal lakes: A comparative field study.

The production of the highly toxic monomethylmercury (MeHg) is heterogenous throughout the water column. Multiple factors have been identified to significantly affect this process, such as an extended anoxic water layer and a deep-water phytoplankton maximum. However, the role of water column heterogeneity on mercury (Hg) cycling is still poorly known, especially concerning the role of zooplankton grazers. Here, four boreal lakes with contrasting characteristics were sampled (i.e., transparency and the presence/absence of fish) at both day and night in order to maximize the heterogeneity in zooplankton abundance both among and within lakes, and to investigate their potential links with Hg vertical heterogeneity. Diel variation of the concentrations of both dissolved total Hg (DTHg) and total Hg (THg) were observed, with night samples significantly higher than day samples. Although this pattern was not related to diel changes in the vertical distribution of zooplankton, results showed that the presence of large copepods (>1.2 mm) and medium-sized (0.6 to 1.2 mm) cladocerans was significantly associated with lower concentrations of DTHg in the water at a given depth, whereas the presence of medium-sized copepods was significantly associated with the concentration of THg. The presence of cladocerans was significantly associated with the ratio between the dissolved MeHg and DTHg (conventionally used as a proxy of methylation potential). Phytoplankton biomass was directly correlated with the concentration of both dissolved and total MeHg and the methylation potential. At the same time, phytoplankton biomass was inversely related to the fraction of DTHg. These results suggest a potential key role of the heterogeneity of biotic factors in the water column, especially of phytoplankton and zooplankton, in the cycling of total Hg and MeHg in boreal lakes.

Long-term effect of acetate and biochar addition on enrichment and activity of denitrifying anaerobic methane oxidation microbes.

The denitrifying anaerobic methane oxidation (DAMO) process plays a crucial role in the global carbon/nitrogen cycles and methane emission control, and also has application potential in biological wastewater treatment. However, given that DAMO microbes are susceptible to external conditions such as additional carbon source in the system, it is essential to evaluate the effect of alternative carbon substance on the enrichment efficiency and metabolic activity of DAMO microbes. To this end, this study investigated the effect of acetate (0.1 mmol/L-R2, 0.5 mmol/L-R3) and biochar addition (R4) on the enrichment and activity of DAMO microbes. The long-term operation showed that the NO2--N and CH4 consumption rates in the reactors almost presented the sequence of R4>R2>R3>R1. However, the short-term activity test with isotope labelling showed the sequence of R2>R4>R1>R3. Furthermore, the addition of acetate and biochar improved the electrochemical activity and extracellular polymeric substance (EPS) secretion in the systems. In R4 reactor, the proportion of DAMO bacteria was the highest (7.20%), indicating that the addition of biochar could promote the enrichment of DAMO bacteria, and Thauera was co-enriched with the proportion increasing from 0.26% to 6.73%. While in R1, R2 and R3 reactors, DAMO bacteria were enriched with relatively low abundances (0.10%, 0.23%, 0.15%, respectively), together with methanogens and denitrifiers. This study showed that biochar and acetate with appropriate concentration could enhance the enrichment and activity of DAMO bacteria, the results can provide reference for the enrichment of DAMO microbes and its application in the biological nitrogen removal of wastewater.