Association between maternal lipid profiles and vitamin D status in second trimester and risk of LGA or SGA: a retrospective study.

Background: Accumulating evidence has linked dyslipidemia during pregnancy to the risk of delivering infants born either large for gestational age (LGA) or small for gestational age (SGA). However, the effects of the vitamin D status on these relationships require further investigation. This study investigated whether the relationship between lipid profiles and the risk of LGA or SGA was influenced by vitamin D levels during the second trimester. Methods: Maternal lipid profile levels, including total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and vitamin D levels, were measured in a cohort of 6,499 pregnant women during the second trimester. Multivariate regression models and subgroup analyses were employed to evaluate the potential associations between maternal lipid profiles, vitamin D levels, and the risk of LGA or SGA. Results: The prevalence of SGA infants was 9.8% (n=635), whereas that of LGA infants was 6.9% (n=447). Maternal TG levels were found to be positively associated with the risk of LGA (odds ratio [OR] = 1.41, 95% confidence interval [CI]:1.17-1.70), whereas a negative association was observed between maternal TG, TC, LDL-C levels, and risk of SGA. Additionally, mothers with higher HDL-C levels were less likely to give birth to an LGA infant (OR=0.58, 95% CI:0.39-0.85). Importantly, associations between TG, TC, LDL-c, and SGA as well as between TG and LGA were primarily observed among pregnant women with insufficient vitamin D levels. As for HDL-C, the risk of LGA was lower in mothers with sufficient vitamin D (OR = 0.42, 95% CI:0.18-0.98) compared to those with insufficient vitamin D (OR = 0.65, 95% CI:0.42-0.99). Conclusion: Vitamin D status during the second trimester exerts a modifying effect on the association between lipid profiles and the risk of LGA and SGA infants.

Ubiquity of Synthetic Phenolic Antioxidants in Children's Cerebrospinal Fluid from South China: First Evidence for Their Penetration across the Blood-Cerebrospinal Fluid Barrier.

Synthetic phenolic antioxidants (SPAs) and relevant transformation products (TPs) are potentially neurotoxic pollutants to which humans are widely exposed. However, their penetration behavior across the brain barrier and associated exposure to the central nervous system (CNS) remain unknown. This study is the first to investigate a wide range of 30 SPAs and TPs, including emerging SPAs, in matched serum and cerebrospinal fluid (CSF) samples from children in Guangzhou, China. Sixty-two children of either sex aged <14 years with nonbloody CSF and complete clinical information were included. The findings demonstrated the ubiquitous occurrence of many SPAs and TPs, particularly BHT, 2,4-di-tert-butylphenol (DBP), AO 1010, AO 1076, BHT-Q, and BHT-quinol, not only in serum but also in the CSF. Median total concentrations of SPAs and TPs were up to 22.0 and 2.63 ng/mL in serum and 14.5 and 2.11 ng/mL in CSF, respectively. On calculating the penetration efficiencies across the blood-CSF barrier (BCSFB) (RCSF/serum, CCSF/Cserum) for selected SPAs and TPs, their RCSF/serum values (median 0.52-1.41) were highly related to their physicochemical properties, indicating that passive diffusion may be the potential mechanism of BCSFB penetration. In addition, the RCSF/serum values were positively correlated with the barrier permeability index RAlb (AlbuminCSF/Albuminserum), indicating that barrier integrity is an important determinant of BCSFB penetration. Overall, these results will improve our perception of human internal exposure to SPAs and lay a solid foundation for assessing the risk of CNS exposure to various SPAs.

Interaction effects of MTHFR C677T and A1298C polymorphisms with maternal glycated haemoglobin levels on adverse birth outcomes.

AIMS: The role of maternal genetic factors in the association between high glycated haemoglobin (HbA1c) levels and adverse birth outcomes remains unclear. MATERIALS AND METHODS: In this study, the maternal HbA1c levels of 5108 normoglycemic pregnant women in China were measured, and A1298C and C677T polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene were genotyped. RESULTS: Elevated HbA1c levels during the second trimester were associated with increased risks of macrosomia, large-for-gestational age (LGA), preterm birth (PTB), and reduced gestational age (p < 0.05). Pregnant women with MTHFR A1298C AA or C677T CT + TT genotypes were susceptible to adverse pregnancy outcomes related to HbA1c levels. Among pregnant women with the A1298C AA genotype, each standard deviation (SD) increase in HbA1c levels increased the risk of PTB by 1.32-times and reduced the gestational age by 0.11 weeks (p < 0.05). For MTHFR C677T CC + TT genotype carriers, higher HbA1c levels were associated with 1.49-, 1.24-, and 1.23-times increased risks of macrosomia, LGA, and PTB, respectively (p < 0.05). A U-shaped curve for PTB risk in relation to HbA1c levels was observed among the C677T CC + TT participants, with a cut-off value of 4.58%. Among subjects with the A1298C AA genotype combined with the C677T CT + TT genotype, each SD increase in HbA1c levels was associated with 1.40 and 1.37-times increased risks of LGA and PTB, respectively. CONCLUSIONS: Our findings highlight the importance of glycaemic control during pregnancy and the potential impact of genetic factors on birth outcomes. However, further large-scale studies are required to confirm these findings.

Release characteristics of volatile organic compounds at residential garbage collection points: a case study of Hangzhou, China.

With the implementation of garbage classification, perishable waste has become increasingly concentrated. This has led to a significant change in the VOC release characteristics at residential garbage collection points, posing a potential risk with unknown characteristics. This study investigated the release characteristics, odor pollution, and health risks of VOCs at garbage collection points under different classification effectiveness, seasons, garbage drop-off periods, and garbage collection point types. The results showed that the average concentration of VOCs released from the garbage sorting collection points (SPs) was 341.43 ± 261.16 µg/m3, and oxygenated compounds (e.g., ethyl acetate and acetone) were the main VOC components. The VOC concentration increased as the community classification effectiveness improved, and it was higher in summer (followed by spring, autumn, and winter). Moreover, the VOC concentrations were higher in the evenings than in the mornings and at centralized garbage collection points (CPs) than at SPs. Further, odor activity value (OAV) assessments indicated that acrolein, styrene, and ethyl acetate were the critical odorous components, with an average OAV of 0.87 ± 0.85, implying marginal odor pollution in some communities. Health risk assessments further revealed that trichloroethylene, benzene, and chlorotoluene were the critical health risk substances, with an average carcinogenic risk (CR) value of 10-6-10-4, and a non-carcinogenic risk (HI) value < 1. These results indicated that HIs were acceptable, but potential CRs existed in the communities. Therefore, VOC pollution prevention and control measures should be urgently strengthened at the garbage collection points in high pollution risk scenarios.

Ipsilateral orolingual angioedema following rhTNK-tPA administration for acute ischemic stroke.

Recombinant human tenecteplase tissue-type plasminogen activator (rhTNK-tPA), a genetically modified variant of conventional alteplase with longer half-life and higher fibrin specificity, has now emerged as a reasonable choice for thrombolytic treatment of acute ischemic stroke (AIS) in China. Orolingual angioedema is a rare but potentially life-threatening complication of intravenous thrombolysis. Currently, there is no documented evidence of orolingual angioedema occurring after thrombolysis with rhTNK-tPA. In this report, we present a unique case of a 75-year-old Chinese man who developed ipsilateral orolingual angioedema following the administration of rhTNK-tPA for AIS. Our case emphasizes the need for caution when using rhTNK-tPA due to its potential to induce ipsilateral orolingual angioedema.

Metagenomics coupled with thermodynamic analysis revealed a potential way to improve the nitrogen removal efficiency of the aerobic methane oxidation coupled to denitrification process under the hypoxic condition.

Aerobic methane (CH4) oxidation coupled to denitrification (AME-D) is a promising wastewater treatment process for CH4 utilization and nitrogen removal. However, it is unclear which CH4-derived carbons are suitable for the AME-D process and how these organics are metabolized. In this study, metagenomics coupled with a thermodynamic model were used to explore the microorganisms and their metabolic mechanisms in an AME-D membrane biofilm reactor (MBfR) with high nitrogen removal efficiency. Results revealed that the aerobic methanotrophs of Methylomonas with the CH4-based fermentation potential were highly enriched and played an important role in CH4 conversion in the MBfR. Bacteria of Xanthomonadaceae, Methylophilaceae, Bacteroidetes, Rhodocyclaceae, Hyphomicrobium were the main denitrifiers. C1 compounds (methanol, formaldehyde and formate) and CH4-based fermentation products are promising cross-feeding intermediates of the AME-D. Specially, by means of integrating the CH4-based fermentation with denitrification, the minimum amount of CH4 required to remove per mole of nitrate can be further reduced to 1.25 mol-CH4 mol-1-NO3-, even lower than that of methanol. Compared to the choice to secrete methanol, type I aerobic methanotrophs require a 15 % reduction in the amount of oxygen required to secrete fermentation metabolites, but a 72 % increase in the amount of CH4-C released. Based on this trade-off, optimizing oxygen supply strategies will help to construct engineered microbiomes focused on aerobic methanotrophs with CH4-based fermentation potential. This study gives an insight into C and N conversions in the AME-D process and highlights the role of CH4-based fermentation in improving the nitrogen removal efficiency of the AME-D process.

Pilot-scale study of innovative mechanically-enhanced dynamic composting for treating kitchen waste.

This study introduced a novel mechanically-enhanced dynamic composting (MEDC) method for treating kitchen waste (KW) through partial-mixing and stratified fermentation. A pilot test varied aeration frequencies (AF) to refine control parameters and explore the maturation mechanism. Results showed that a moderate AF (10 min/4 h) achieved optimal efficiency, with a compost germination index of 123 % within 15 d. Moderate AF enhanced the growth of Corynebacterium_1 (25.4 %) and Saccharomonospora (10.5 %) during the low-temperature stage and Bacillus growth (91.3 %) during the maturation stage. Moreover, it enhanced microbial interactions (with an average degree of 19.9) and promoted substrate degradation and transformation, expediting heating and maturation. Multivariate dimensionality reduction analysis showed the MEDC accomplished rapid composting through stratified composting, dividing the reactor into distinct functional zones: feeding, low-temperature, high-temperature, and maturation. This enabled efficient microorganism enrichment and material degradation, expediting KW decomposition and maturation. This study offers a promising alternative for accelerated KW composting.

Blood-cerebrospinal fluid barrier permeability of metals/metalloids and its determinants in pediatric patients.

Concerns regarding adverse effects of metal/metalloids exposure on brain development and neurological disorders among children are increasing. However, the transport patterns of metals/metalloids across the blood-cerebrospinal fluid barrier (BCSFB) need to be clarified in children. A total of 99 Chinese pediatric patients were enrolled from February 2020 to August 2021, with a median age of 6.76 months. We detected 16 metal/metalloid levels in matched serum and cerebrospinal fluid (CSF) samples using inductively coupled plasma mass spectrometry. The BCSFB permeability of metals/metalloids were estimated and the potential effects of biomedical parameters were explored. Most metals/metalloids were detectable among > 80.0% of CSF samples. Significant correlations were observed between strontium (Sr, r = 0.46), molybdenum (Mo, r = 0.50), and cadmium (Cd, r = 0.24) concentrations in serum and CSF (P < 0.05). Ratios of metal/metalloid levels in CSF to serum (Rmetal) ranged from 0.02 to 0.74, and hazardous metals/metalloids including arsenic (As), Cd, lead (Pb), thallium (Tl), and manganese (Mn) showed high transfer efficiencies across the BCSFB (Rmetals > 0.5). With the adjustment of age and sex, albumin, ß2-microglobulin, and total protein levels in CSF were positively associated with copper (Cu) permeability (FDR-adjusted P < 0.05), while glucose in CSF was negatively correlated with calcium (Ca), Cu, Sr, and Mo BCSFB permeability (FDR-adjusted P < 0.05). Q-Alb promoted Cu permeability across the BCSFB (FDR-adjusted P < 0.001), while C-reactive protein levels in serum were positively associated with selenium (Se) permeability (FDR-adjusted P = 0.046). For the first time, our findings provided data for the BCSFB permeability of 16 metals/metalloids in children, and indicated that some biomedical parameters could influence the transformation of metals/metalloids from serum to CSF. Metals/metalloids with strong BCSFB permeability warrant attention for their potential neurotoxicity.

Regionalized life-cycle monetization can support the transition to sustainable rural food waste management in China.

Innovative recycling technologies can help curb food waste, yet their implementation often involves trade-offs among different environmental issues and among environmental, economic and social issues. Monetization can provide a solution to integrate all environmental impacts across the life cycle of food waste and to enable a normalized evaluation with economic accounting. Herein, a Chinese regionalized monetization model was applied to various indicators related to the environment, resource depletion and human health to assess ten typical rural food waste recycling technologies in Zhejiang province. The results reveal that biodrying and maturity and two bioconversion options are promising solutions, considering both environmental and economic impacts as well as the shifting of environmental impacts among different compartments as hidden risks. The monetization method proposed here could be applied to other sectors to support decision-making towards more sustainable development.

Soft magnetic ferrite for enhanced anaerobic digestion of food waste: Effects on methane production and magnetic recovery.

Soft magnetic ferrite (SMF) is a potentially efficient anaerobic digestion (AD) additive that can be recovered simultaneously along with the microorganisms it carries. In this study, two typical SMFs (Fe3O4 and γ-Fe2O3) were compared in batch experiments to investigate their effects on food waste AD and to examine the recovery characteristics of both the SMFs and the microorganisms they carried after AD. The results showed that Fe3O4 and γ-Fe2O3 addition increased methane production by 31% and 68% respectively, compared with the control treatment. Both SMF materials and enriched microorganisms were effectively adsorbed post-AD using a magnet. The observed enhancement in biomethanization after SMF addition was likely due to enhanced syntrophic acetate oxidation and hydrogenotrophic methanogenesis, and direct interspecific electron transfer. γ-Fe2O3 outperformed Fe3O4 due to its high recycling rate and ability to promote Methanosarcina growth. This study provides a potential economically efficient solution for developing AD enhancement technologies.

Exploitation alters microbial community and its co-occurrence patterns in ionic rare earth mining sites.

The exploitation of ion-adsorption rare earth elements (REEs) deposits results in serious ecological and environmental problems, which has attracted much attention. However, the influences of exploitation on the prokaryotic communities and their complex interactions remain poorly understood. In the present study, bacterial and archaeal communities, as well as ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA), in and around REEs mining area were investigated through high throughput sequencing and quantitative polymerase chain reaction (qPCR). Our results indicated that mining soil was characterized by poor soil structure, nutrient deficiency, and high concentrations of residual REEs. Oligotrophic bacteria (e.g., Chloroflexi and Acidobacteriota) were dominant in unexploited soil and mining soil, while copiotrophic bacteria (Proteobacteria and Actinobacteriota) were more abundant in surrounding soil. Nutrient was the key factor affecting microbial variation and abundance in mining soil. The bacterial community was more sensitive to REEs, while the archaeal communities were relatively stable. As the key members for ammonia oxidation, AOA outnumbered AOB in all the soil types, and the former was significantly influenced by pH, nutrients, and TREEs in mining soil. The microbial co-occurrence network analysis demonstrated that exploitation significantly influenced topological properties, decreased the complexity, and resulted in a much unstable network, leading to a more fragile microbial ecosystem in mining areas. Notably, the abundance of keystone taxa decreased after exploitation, and oligotrophic groups (Chloroflexi) replaced copiotrophic groups (Proteobacteria and Actinobacteriota) as the key to rebuilt a co-occurrence network, suggesting potentially important roles in maintaining network stability. The current results are of great significance to the ecological risk assessment of REEs exploitation.

Maternal pre-pregnancy BMI, MTHFR polymorphisms, and the risk of adverse pregnancy outcomes in pregnant women from South China: a retrospective cohort study.

BACKGROUND: Increasing evidence suggests an association between maternal pre-pregnancy body mass index (pre-BMI) and adverse pregnancy outcomes. However, the effects of methylenetetrahydrofolate reductase (MTHFR) polymorphisms on these relationships require further investigation. This study aimed to investigate whether the relationship between pre-BMI and the risk of adverse pregnancy outcomes was influenced by MTHFR gene polymorphisms. METHODS: A total of 5614 mother-fetus pairs were included in the study. The odds ratios (OR) of adverse pregnancy complications, including gestational diabetes mellitus (GDM), gestational hypertension (GHT), cesarean delivery (CS), and premature rupture of membranes (PROM), were estimated using adjusted logistic regression models and subgroup analysis. RESULTS: Pregnant women with higher pre-BMI values were positively related to the risk of GDM, GHT, and CS. In the subgroup analysis, underweight BMI was associated with a decreased risk of CS and GDM in pregnant women with the MTHFR A1298C AA or C677T CC genotype, while overweight/obese BMI was associated with an increased risk of GDM and CS in different MTHFR variants. Moreover, pregnant women with MTHFR A1298C AC + CC or C667T CC were found to have an increased risk of GHT in the MTHFR A1298C AA or C667T CT + TT genotype. A remarkable association was observed between the obesity group with MTHFR A1298C AC + CC (OR = 6.49, CI: 2.67-15.79) and the overweight group with the C667T CC genotype (OR = 4.72, CI: 2.13-10.45). CONCLUSIONS: MTHFR gene polymorphisms exert a modifying effect on the association between maternal pre-BMI and the risk of GHT, CS, and GDM. Pregnant women with a high pre-BMI with specific MTHFR genotypes should be considered for GHT development.

Pilot-scale study of step-feed anaerobic coupled four-stage micro-oxygen gradient aeration process for treating digested swine wastewater with low carbon/nitrogen ratios.

This study developed an innovative step-feed anaerobic coupled four-stage micro-oxygen gradient aeration process to treat digested swine wastewater. An anaerobic zone was used for prepositive denitrification; four micro-oxygen reactors (zones O1-O4) were used for simultaneous partial nitrification and denitrification through low-dissolved oxygen gradient control, step-feed, and swine wastewater-digested swine wastewater distribution. The nitrogen-removal efficiency was satisfactory (93 ± 3 %; effluent total nitrogen, 53 ± 19 mg/L). Mass balance coupled with quantitative polymerase chain reaction analysis revealed that simultaneous partial nitrification and denitrification was achieved in four micro-oxygen zones. Zones O1 were the major denitrification zones for nitrogen removal; nitrification was primary happened in zones O2 and O3. Correlation analysis confirmed that low-dissolved oxygen gradient control was the key to achieving efficient nitrogen removal. This study provides a low oxygen energy consumption method to treat digested swine wastewater with a low carbon/nitrogen ratio (<3).

Prognostic performance of serum YKL-40 for one-year clinical outcomes in acute ischemic stroke.

BACKGROUND: Effects of YKL-40 on one-year clinical outcomes including poor clinical outcome, all-cause mortality, and stroke recurrence among acute ischemic stroke (AIS) patients remained elusive. The purpose of this study was to explore the association between serum YKL-40 at admission and one-year clinical outcomes in AIS patients. METHODS: In this prospective cohort study, a total of 1002 participants out of 1361 AIS patients from two centers were included for current analysis. Serum YKL-40 concentrations were measured via enzyme-linked immunosorbent assay. Multivariable logistic or Cox regression were performed to explore the independent association of YKL-40 with one-year clinical outcomes, including poor outcome (modified Rankin Scale of 3-6), all-cause mortality, and recurrent stroke. C-statistic, net reclassification index (NRI) and integrated discrimination improvement (IDI) were calculated to evaluate the discriminatory and predictive power of YKL-40 when added to conventional model. RESULTS: Compared with the first quartile of YKL-40, the adjusted odds ratios or hazard ratios with 95% confidence intervals of the fourth quartile were 3.032 (1.627-5.650) for poor outcome, 2.886 (1.320-6.308) for all-cause mortality and 1.694 (0.906-3.169) for recurrent stroke. The addition of serum YKL-40 to conventional model significantly improved reclassification for poor outcome (NRI 0.053, P = 0.031; IDI 0.018, P = 0.001) and all-cause mortality (NRI 0.162, P = 0.036). CONCLUSIONS: Elevated serum YKL-40 at admission might be independently associated with one-year poor outcome and all-cause mortality but not stroke recurrence among Chinese AIS patients.

Reducing nitrogen loss during kitchen waste composting using a bioaugmented mechanical process with low pH and enhanced ammonia assimilation.

Exploring the regulation of nitrogen transformation in bioaugmented mechanical composting (BMC) process for rural kitchen waste (KW) is essential to avoid the "not-in-my-backyard" phenomenon caused by nitrogen loss. Herein, nitrogen transformation and loss in BMC versus conventional pile composting (CPC) of KW were compared. The results showed that the total nitrogen loss in the BMC was 6.87-39.32 % lower than that in the CPC. The main pathways to prevent nitrogen loss in the BMC were reducing NH3 by avoiding a sharp increase in pH followed by transforming the preserved NH4+-N into recalcitrant nitrogen reservoir via enhanced ammonia assimilation. The enriched thermophilic bacteria with mineralization capacities (e.g., Bacillus and Corynebacterium) during rapid dehydration and heating in the BMC accumulated organic acids and easy-to-use carbon sources, which could lead to lower pH and ammonia assimilation enhancement, respectively. This study provides new ideas for formulating low-cost nitrogen conservation strategies in decentralized KW composting.

Polymorphisms in gene MTHFR modify the association between gestational weight gain and adverse birth outcomes.

Evidence suggests a potential relationship between gestational weight gain (GWG) and adverse birth outcomes. However, the role of maternal genetic polymorphisms remains unclear. This study was conducted to investigate whether the relationship of GWG with risk of adverse birth outcomes was modified by methylenetetrahydrofolate reductase (MTHFR) polymorphisms. A total of 2,967 Chinese pregnant women were included and divided into insufficient, sufficient, and excessive groups based on the Institute of Medicine (IOM) criteria. Polymorphisms of C677T and A1298C in gene MTHFR were genotyped. Multivariable logistic regression models were introduced after controlling major confounders. Excessive GWG was found to increase the odds ratio (OR) for macrosomia [OR = 3.47, 95% confidence interval (CI): 1.86-6.48] and large-for-gestational age (LGA, OR = 3.25, 95% CI: 2.23-4.74), and decreased the OR for small-for-gestational age (SGA, OR = 0.60, 95% CI: 0.45-0.79). Pregnant women with insufficient GWG had a higher frequency of SGA (OR = 1.68, 95% CI: 1.32-2.13) and a lower rate of LGA (OR = 0.51, 95% CI: 0.27-0.96). Interestingly, significant associations of GWG categories in relation to low birth weight (LBW), macrosomia, and SGA were only suggested among pregnant women with MTHFR A1298C AA genotype. Among pregnant women with insufficient GWG group, an increased risk of 3.96 (95% CI: 1.57-10.01) for LBW was observed among subjects with the A1298C AA genotype, compared to the AC+CC genotype group. GWG categories are closely related to LBW, macrosomia, SGA and LGA, and the associations were modified by the polymorphism of MTHFR A1298C.

Heterogeneity of CH4-derived carbon induced by O2:CH4 mediates the bacterial community assembly processes.

The mechanism by which O2:CH4 controls microbial community assembly in the process of aerobic methane oxidation coupled to denitrification (AMED) remains largely uncharacterized, which hinders the design of engineering microbiomes for the AMED. In this study, the changes in the bacterial community in fed-batch serum bottle reactors under different O2:CH4 ratios were systematically characterized. The ratios of CH4 consumption to the amount of nitrate removal in the treatment with O2:CH4 = 1.5:1, O2:CH4 = 0.5:1, and O2:CH4 = 0.25:1 were 13.1 ± 3.4, 4.7 ± 1.1, and 5.9 ± 3.0 mol-CH4 mol-1-NO3-, respectively. The α-diversity of the bacterial community increased as O2:CH4 decreased. Significantly different selection patterns were found for the high and low O2:CH4 ratios. The coherence process dominated the selection at high O2:CH4 ratios, while the diversification process played a role when O2:CH4 was low. Differences were also observed in the composition of CH4-derived carbon between treatments with O2:CH4 = 1.5:1 and O2:CH4 = 0.5:1. Compared with the treatments with O2:CH4 = 1.5:1, the concentrations of methanol, formaldehyde, acetate, and ethanol in the treatment with O2:CH4 = 0.5:1 were significantly higher, while the concentration of formate was significantly lower. The heterogeneity of CH4-derived carbon induced by O2:CH4 was likely to be responsible for the differences in the selection patterns. Our findings bridge the gaps between the observations of bacterial community perturbations and ecological community assembly theories, highlighting the potential of the bottom-up design approach to improve the nitrate removal rate of the AME-D.

Molecular Characterization of Distinct Fungal Communities in the Soil of a Rare Earth Mining Area.

The exploitation of ion-absorbed rare earth elements (REEs) has caused serious ecological destruction and environmental pollution. Effects on soil fungal structure and diversity exerted by mining activities are usually ignored, although fungus is one of the most important components in soil ecosystems. In the present research, quantitative polymerase chain reaction (qPCR) and high-throughput Illumina MiSeq sequencing were conducted to characterize fungal community composition and structure in soil of a rare earth mining area after in situ leaching. Statistical analyses, network, and FUNGuild were used to conduct in-depth analyses. Ascomycota, Basidiomycota, and Glomeromycota were the most abundant phyla in the mining soils. Fungal community structures were stable after leaching practice, but nutrition contents (organic matter, TC, and TN) significantly and positively contributed to fungal abundances and diversities. Saprotrophs in phyla Ascomycota and Basidiomycota were the dominant fungal trophic mode, and they played critical roles in nutrient cycling, transformation processes, and reducing REE toxicity. Symbiotrophs of phyla Glomeromycota contributed to soil aggregation and slowing down nutrient losses after in situ leaching practice. In addition, fungi could regulate the interactions between species to resist the harsh environment of REE toxicity or ammonium caused by in situ leaching practice.

Elevation of NO3--N from biochar amendment facilitates mitigating paddy CH4 emission stably over seven years.

Biochar application into paddy is an improved strategy for addressing methane (CH4) stimulation of straw biomass incorporation. Whereas, the differentiative patterns and mechanisms on CH4 emission of straw biomass and biochar after long years still need to be disentangled. Considering economic feasibility, a seven-year of field experiment was conducted to explore the long-term CH4 mitigation effect of annual low-rate biochar incorporation (RSC, 2.8 t ha-1), with annual rice straw incorporation (RS, 8 t ha-1) and control (CK, with no biochar or rice straw amendment incorporation) as a comparation. Results showed that RSC mitigated CH4 emission while RS stimulated CH4 significantly (p < 0.05) and stably over 7 experimental years compared with CK. RSC mitigated 14.8-46.7% of CH4 emission compared with CK. In comparison to RSC, RS increased 111-950.5% of CH4 emission during 7 field experimental years. On the 7th field experimental year, pH was significantly increased both in RS and RSC treatment (p < 0.05). RSC significantly (p < 0.05) increased soil nitrate (NO3--N) compared with RS while RS significantly (p < 0.05) increased dissolved carbon (DOC) compared to RSC. Soil NO3--N inhibition on methanogens and promotion on methanotrophs activities were verified by laboratory experiment, while soil pH and DOC mainly promoted methanogens abundance. Significantly (p < 0.05) increased DOC and soil pH enhanced methanogens growth and stimulated CH4 emission in RS treatment. Higher soil NO3--N content in RSC than CK and RS contributed to CH4 mitigation. Soil NO3--N and DOC were identified as the key factors differentiating CH4 emission patterns of RS and RSC in 2019. Collectively, soil NO3--N impacts on CH4 flux provide new ideas for prolonged effect of biochar amendment on CH4 mitigation after years.