81. 题目: Investigation of the migration of natural organic matter-iron-antimony nano-colloids in acid mine drainage
Colloids can potentially affect the efficacy of traditional acid mine drainage (AMD) treatment methods such as precipitation and filtration. However, it is unclear how colloids affect antimony (Sb) migration in AMD, especially when natural organic matter (NOM) is present. To conduct an in-depth investigation on the formation and migration behavior of NOM, iron (Fe), Sb and NOM-Fe-Sb colloids in AMD, experiments were performed under simulated AMD conditions. The results demonstrate significant variations in the formation of NOM-Fe-Sb colloids (1–3–450 nm) as the molar ratio of carbon to iron (C/Fe) increases within acidic conditions (pH = 3). Increasing the C/Fe molar ratio from 0.1 to 1.2 resulted in a decrease in colloid formation but an increase in particulate fraction. The distribution of colloidal Sb, Sb(III), and Fe(III) within the NOM-Fe-Sb colloids decreased from 68 % to 55 %, 72 % to 57 %, and 68 % to 55 %, respectively. Their distribution in the particulate fraction increased from 28 % to 42 %, 21 % to 34 %, and 8 % to 27 %. XRD, FTIR, and SEM-EDS analyses demonstrated that NOM facilitates the formation and crystallization of Fe3O4 and FeSbO4 crystalline phases. The formation of the colloids depended on pH. Our results indicate that NOM-Fe-Sb colloids can form when the pH ≤ 4, and the proportion of colloidal Sb fraction within the NOM-Fe-Sb colloids increased from 9 % to a maximum of 73 %. Column experiments show that the concentration of NOM-Fe-Sb colloids reaches its peak and remains stable at approximately 3.5 pore volumes (PVs), facilitating the migration of Sb in the porous media. At pH ≥ 5, stable NOM-Fe-Sb colloids do not form, and the proportion of colloidal Sb fraction decreases from 7 % to 0 %. This implies that as pH increases, the electrostatic repulsion between colloidal particles weakens, resulting in a reduction in the colloidal fraction and an increase in the particulate fraction. At higher pH values (pH ≥ 5), the repulsive forces between colloidal particles nearly disappear, promoting particle aggregation. The findings of this study provide important scientific evidence for understanding the migration behavior of NOM-Fe-Sb colloids in AMD. As the pH gradually shifts from acidic to near-neutral pH during the remediation process of AMD, these results could be applied to develop new strategies for this purpose.
82. 题目: Removal of strontium by nanofiltration: Role of complexation and speciation of strontium with organic matter
Strontium (Sr) removal from water is required because excessive naturally occurring Sr exposure is hazardous to human health. Climate and seasonal changes cause water quality variations, in particular quality and quantity of organic matter (OM) and pH, and such variations affect Sr removal by nanofiltration (NF). The mechanisms for such variations are not clear and thus OM complexation and speciation require attention. Sr removal by NF was investigated with emphasis on the role of OM (type and concentration) and pH (2–12) on possible removal mechanisms, specifically size and/or charge exclusion as well as solute-solute interactions. The filtration results show that the addition of various OM (10 types) and an increase of OM concentration (2–100 mgC.L−1) increased Sr removal by 10-15%. The Sr-OM interaction was enhanced with increasing OM concentration, implying enhanced size exclusion via Sr-OM interaction as the main mechanism. Such interactions were quantified by asymmetric flow field-flow fractionation (FFFF) coupled with an inductively coupled plasma mass spectrometer (ICP-MS). Both extremely low and high pH increased Sr removal due to the enhanced charge exclusion and Sr-OM interactions. This work elucidated and verified the mechanism of OM and pH on Sr removal by NF membranes.
83. 题目: Biochar leachate reduces primary nitrogen assimilation by inhibiting nitrogen fixation and microbial nitrate assimilation
Biochar contains biotoxic aromatic compounds, and their influence on nitrogen-fixing cyanobacteria, the critical nitrogen fixer in paddy soil, has never been tested. Here, the physiological, metabolomic, and transcriptomic analyses of Nostoc sp. PCC7120 in response to biochar leachate were performed. The results suggested that biochar leachate inhibited the efficiency of photosynthesis, nitrogen fixation, and nitrate assimilation activities of nitrogen-fixing cyanobacteria. Biochar leachate containing aromatic compounds and odd- and long-chain saturated fatty acids impaired the membrane structure and antenna pigments, damaged the D1 protein of the oxygen evolution complex, and eventually decreased the electron transfer chain activity of photosystem II. Moreover, the nitrogen fixation and nitrate assimilation abilities of nitrogen-fixing cyanobacteria were inhibited by a decrease in photosynthetic productivity. A decrease in iron absorption was another factor limiting nitrogen fixation efficiency. Our study highlights that biochar with relatively high contents of dissolved organic matter poses a risk to primary nitrogen assimilation reduction and ecosystem nitrogen loss. Further evidence of the potential negative effects of biochar leachates on the fixation and assimilation capacity of nitrogen by soil microbes is needed to evaluate the impact of biochar on soil multifunctionality prior to large-scale application.
84. 题目: Eutrophication-driven infochemical dimethylsulfide accelerates carbon transfer in freshwater food chain
Dimethylsulfide (DMS) is a major organic sulfide in aquatic ecosystems and an infochemical that is considered as a key predictor of changes in energy and material fluxes and stocks. It is largely unknown how DMS changes and affects the food webs and material cycles in eutrophicated freshwater. In this study, field monitoring and literature surveys were conducted to analyze the effects of eutrophication on DMS concentrations. Daphnia-zebrafish microcosms were then used to investigate the effects of DMS concentrations on carbon transfer. The results demonstrated that the concentration of DMS was increased by eutrophication related indicators (chlorophyll and phosphorus). Eutrophication driven DMS altered carbon transfer in the freshwater food chain. Low concentrations (0.1–1 nM) of DMS promoted the predation of daphnia by zebrafish compared to the 0.01 nM DMS, which further stimulated the total carbon transfer from daphnia to zebrafish and altered the dissolved organic carbon (DOC) distribution in water. High concentrations (10–100 nM) of DMS did not alter zebrafish predation on daphnia and carbon transfer. DOC excreted by zebrafish altered carbon emission potential, and DMS in water showed a unimodal relationship with the carbon emission potential, peaking at 0.40 nM DMS. Keeping the DMS in water at 1.82 nM may maintain a lower carbon emission potential. These results improved the understanding of the effects of eutrophication on DMS, demonstrated the ecological role of DMS on freshwater fish and the carbon cycle, estimated the effects of DMS on the carbon emission potential of fish, and offered new insights into the management of eutrophication.
85. 题目: Effects of nitrogen and phosphorus addition on the mineralization potential of soil organic carbon and the corresponding regulations in the Tibetan alpine grassland
As a crucial property for assessing the stability of soil organic carbon (SOC), the mineralization potential of SOC (RSOC) is often considered vital for soil carbon (C) dynamics. Previous studies have investigated the responses of RSOC and the corresponding regulation of increased nitrogen (N) and phosphorus (P) inputs, among which, the response of RSOC would affect SOC accumulation directly, emphasizing the significance of investigating RSOC. Hence, based on a long-term nutrient addition experiment in a Tibetan alpine grassland, this study assessed RSOC using a 45-day soil incubation experiment with 13C-glucose labeling method and explored the underlying mechanisms. The results demonstrated bacterial richness and diversity decreased in the topsoil due to the lower pH caused by the continuous N addition, whereas fungal richness and diversity had no significant change. And RSOC decreased with N addition in the topsoil because of suppressing the physiological process of microbes for N. Our results highlighted the crucial role of C availability (indicated by dissolved organic carbon) and N availability (indicated by total nitrogen) in controlling RSOC with long-term nutrient addition in the top- and subsoil, respectively. Overall, this study elucidated the impact of N and P addition on RSOC and offered the regulatory mechanisms of RSOC by considering soil, plant and microbial properties. These findings can serve as a basis for anticipating the changes in SOC dynamics in response to enhanced N and P deposition.
86. 题目: Rice husk and its derived biochar assist phytoremediation of heavy metals and PAHs co-contaminated soils but differently affect bacterial community
In order to evaluate the feasibility of rice husk and rice husk biochar on assisting phytoremediation of polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) co-contaminated soils, a 150-day pot experiment planted with alfalfa was designed. Rice husk and its derived biochar were applied to remediate a PAHs, Zn, and Cr co-contaminated soil. The effects of rice husk and biochar on the removal and bioavailability of PAHs and HMs, PAH-ring hydroxylating dioxygenase gene abundance and bacterial community structure in rhizosphere soils were investigated. Results suggested that rice husk biochar had better performance on the removal of PAHs and immobilization of HMs than those of rice husk in co-contaminated rhizosphere soil. The abundance of PAH-degraders, which increased with the culture time, was positively correlated with PAHs removal. Rice husk biochar decreased the richness and diversity of bacterial community, enhanced the growth of Steroidobacter, Bacillus, and Sphingomonas in rhizosphere soils. However, Steroidobacter, Dongia and Acidibacter were stimulated in rice husk amended soils. According to the correlation analysis, Steroidobacter and Mycobacterium may play an important role in PAHs removal and HMs absorption. The combination of rice husk biochar and alfalfa would be a promising method to remediate PAHs and HMs co-contaminated soil.
Co-existence of polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) in soils causes large harm to human and environment. This study investigated the feasibility of rice husk and its derived biochar on assisting phytoremediation of PAHs and HMs co-contaminated soils and elucidated the change of bacterial community. Rice husk biochar did better in enhancing phytoremediation of co-contaminated soils than that of rice husk. These results show a highly value in the practical application of in-situ remediation of PAHs and HMs co-contaminated soil, and provide a deeper understanding of the pollutants removal mechanism from a molecular biology.
87. 题目: Effect of biochars on the immobilization and form of Cadmium (Cd) in simulated Cd deposition of iron rich soils
Atmospheric deposition of Cd poses a serious threat to ecosystem security. Biochar is widely used for polluted soil remediation, however, whether biochar already applied to the soil can reduce the hazards of newly deposited Cd remains to be studied. Thus, an indoor cultural experiment and static adsorption method were conducted to study the isothermal and kinetic adsorption processes of three types of biochar (rice husk, rubber wood, and tobacco stem biochars) on Cd in iron rich soils and the effect of biochar on the morphological distribution of Cd in the soil and the soil pH. The results showed that the soil with biochar in our study could quickly fix “the new deposited Cd” in the soil in 3 h with the maximum adsorption capacity in rubber wood biochar-treated sample (3227.34 mg/kg）. The addition of all three biochar treatments significantly increased the soil pH and reduced the soil exchange state Cd content, with a 13.69–17.32% increase in the pH and a 13.22–54.39% reduction in the exchange state Cd content when contrasted with the control, which could promote those Cd converting into unavailable Cd (carbonate-bound form Cd, Fe-Mn oxide-bound form Cd, or residual form Cd) for crops. In summary, the addition of three kinds of biochar treatments could effectively reduce the ecological and environmental risk of soil that was contaminated by Cd and could provide a reliable theoretical basis for the effect of biochar on the improvement of the quality of soil that is contaminated by heavy metals.
88. 题目: Impacts of climate change on crop production and soil carbon stock in a continuous wheat cropping system in southeast England
Understanding dynamics of soil organic carbon (SOC) stock in agroecosystems under climate change is imperative for maintaining soil productivity and offsetting greenhouse gas emissions. Simulations with the SPACSYS model were conducted to assess the effects of future climate scenarios (RCP2.6, RCP4.5 and RCP8.5) and fertilisation practices on crop yield and SOC stock by 2100 for a continuous winter wheat cropping system in southeast England. Weather data between 1921 and 2000 was considered as the baseline. SPACSYS was first calibrated and validated with the data of the Broadbalk continuous winter wheat experiment for over a century. Six treatments were used: no fertiliser, a combination of chemical nitrogen, phosphorus and potassium with three nitrogen application rates (N1PK, N3PK and N5PK), manure only (FYM, close N application rate to N5PK) and a combination of manure and chemical nitrogen application (FYMN, the same chemical N application rate as N3PK). Compared with the observations, SPACSYS was able to simulate grain yields and dynamics of SOC and TN stocks. Our predications showed that wheat yield would increase by 5.8–13.5% for all the fertiliser application treatments under future climate scenarios compared to that under the baseline because of a gradual increase in atmospheric CO2 concentration. Meanwhile, the SOC stock can increase for the practices under the scenarios except the NPK fertiliser practices under RCP2.6. Increased C input through “CO2-fertilisation effects” can compensate C losses by soil respiration under the RCP scenarios. We concluded that manure application practices can be considered as a sustainable strategy for enhancing wheat yield and soil C sequestration under the future climate scenarios.
89. 题目: Spatial distribution characteristics and interaction effects of DOM and microbial communities in kelp cultivation areas
The influence of macroalgae cultivation on aquaculture carbon sinks is significant, with microbial carbon (C) pumps contributing to a stable inert dissolved carbon pool in this context. Concurrently, dissolved organic matter (DOM) exchange at the marine sediment-water interface profoundly affects global ecosystem element cycling. However, the interactions between DOM and bacterial communities at the sediment-water interface in kelp cultivation areas, especially regarding microbial function prediction, have not been fully explored. This study analyzed the DOM characteristics, environmental factors, and bacterial community structure in the Tahewan kelp——Saccharina japonica cultivated area and compared them with those in non-cultivated areas. The results indicated significantly higher dissolved organic carbon (DOC) concentrations in the kelp culture area, particularly in surface seawater and overlying water. The dominant bacterial phyla in both regions included Pseudomonadota, Actinomycetota, and Bacteroidota in both regions, while Desulfobacterota was more prevalent in the sediment environment of the cultivated region. Parallel factor analysis (EEM-PARAFAC) was used to identify DOM components, among which component C2 (a microbial humic-like substance DOM) was highly resistant to microbial degradation. We infer that C2 has similar properties to recalcitrant dissolved organic matter (RDOM). Analysis of the predicted functional genes based on 16S rRNA gene data showed that methanol oxidation, methanotrophy, and methanotrophy were significant in the bottom seawater of the cultivation area. The carbon (C), nitrogen (N), and sulfur (S) cycle functional genes in the sediment environment of the kelp cultivation area were more active than those in other areas, especially in which sulfate reduction and denitrification were the two main processes. Furthermore, a DOM priming effect was identified in the cultivated sediment environment, where kelp-released labile dissolved organic matter (LDOM) stimulates rapid degradation of the original RDOM, potentially enhancing C sequestration.
90. 题目: Straw addition and low soil moisture decreased temperature sensitivity and activation energy of soil organic matter
Incorporating straw into soils is an effective and cost-efficient method for sequestering organic carbon (C) and enhancing soil quality. However, the interactive effects of soil moisture and temperature on soil organic matter (SOM) mineralization have remained unclear in the presence of plant residues. We assessed the impacts of 13C-labeled maize (Zea mays) straw on SOM mineralization in two soils with contrasting soil C content (3.0 % and 6.8 %) under two moisture levels (45 % or 65 % water holding capacity (WHC)) and two temperatures (12 °C or 22 °C) through an experimental incubation. In the absence of straw addition, CO2 production at 22 °C was 2–3 times more than at 12 °C, and was 31–40 % higher at 65 % WHC than at 45 % WHC in both soils. Soil temperature and moisture interactively affected straw decomposition. After a 66-day incubation, approximately 7–11 % of straw was decomposed to CO2, contributing 44–67 % to the total CO2 production. Straw addition increased SOM mineralization across all temperature and moisture levels, resulting in a positive priming effect (PE). The highest PE was observed at 45 % WHC and 22℃ in both soils. The temperature sensitivity (Q10 value) of native SOM mineralization decreased with straw addition due to higher quality SOM (i.e., higher the basal microbial respiration rate per unit organic C at 0 °C and DOC/SOC) compared with control (no straw addition). The Q10 values of SOM and straw decomposition was higher at 65 % WHC compared to 45 % WHC, indicating that drought conditions have potential to dampen effects of temperature on the decomposition. We also discovered a positive correlation between Q10 and activation energy and a negative correlation with soil C quality, providing support for the C quality temperature hypothesis. In summary, our findings contribute to advancing our understanding of how soil C dynamics respond to exogenous C inputs under environment change.
91. 题目: Promoting methane production during anaerobic digestion with biochar: Is it influenced by quorum sensing?
Biochar has been proved to improve methane production in anaerobic digestion (AD) of food waste, but the role of biochar related to quorum sensing (QS)-mediated inter-microbial communication during AD has not been sufficiently revealed. Results indicated that about 20 % increase in cumulative methane production in the digester with BC700 addition (298.8 mL/gVS) over that without biochar. The concentration of QS signal molecule (especially N-acyl-homoserine lactones) increased with the addition of biochar, and particularly the concentration of 3OC6-HSL in the digester containing BC700 (9.0615 μg/L) increased significantly. Accordingly, the electroactive microorganisms were enriched predominantly such as DMER64 and Methanospirillum. The abundance of key enzyme activities (including acetate kinase and coenzyme F420) increased with BC700 addition, especially coenzyme F420 which was higher by 33.0 % compared to without biochar. The microbial metabolism functions based on metagenomics suggested that carbon metabolism, extracellular electron transfer, and QS related genes were enhanced with the addition of biochar. This study provided new evidence about the underlying role of QS-mediated inter-microbial communication and extracellular electron transfer in elucidating the mechanism of biochar-enhanced methanogenesis.
92. 题目: Is non-legume green manure rotation or straw biochar more effective in promoting peanut production?
In contemporary agronomy, the adoption of green manure rotation and straw biochar amendment has emerged as an important strategy, explicitly targeting the enhancement of soil health and crop productivity. This study aimed to investigate the impacts of incorporating non-legume green manure rotation and straw biochar application on soil physicochemical properties, microbial community structure, and peanut production, along with a comprehensive assessment of their effectiveness. Over the three-year experimental period, the treatments included: a control treatment that followed traditional planting practices (PT); ryegrass was planted and then returned to the field before peanut cultivation (GM); and straw biochar was applied prior to peanut planting (BC). The results demonstrated that both GM and BC treatments led to a significant (P < 0.05) reduction in soil bulk density. They also increased water-stable aggregates measuring >5 mm and 2–5 mm, while decreasing aggregates measuring 0.25–2 mm, 0.053–0.025 mm, and < 0.053 mm when compared to PT. Additionally, GM and BC improved soil mean weight diameter and geometric mean diameter. They also enhanced the soil's organic carbon and nitrogen content, attributing these changes to shifts in microbial taxa crucial for carbon and nitrogen fluxes, as revealed by soil metagenomic sequencing analysis. Specifically, GM increased the relative abundance of genera such as Solirubrobacter, Arthrobacter, and Bradyrhizobium, while BC favored Methylibium, Burkholderia, and Acinetobacter, etc. Despite both GM and BC significantly increasing yield and net income, a comprehensive assessment using the entropy weight-TOPSIS indicates that non-legume green manure rotation is more effective in promoting peanut production based on soil quality attributes, inputs, and outputs.
93. 题目: Effect of colour calibration on the prediction of soil organic matter content based on original soil images obtained from smartphones under different lighting conditions
The ability to quickly and accurately determine soil organic matter (SOM) content is critical for effective soil management decisions. Using the colour of soil images captured by smartphones to predict SOM content has emerged as a promising alternative to traditional wet chemistry methods. However, natural environments can present a complex array of light conditions that can compromise the accuracy and consistency of soil image colour acquisition, thus limiting the method's applicability. To address this issue, we propose five colour calibration patterns (C0 (no calibration), C1 (neutral grey), C2 (RGB), C3 (RGBCMY), and C4 (24 colours)), based on a 24-colour standard card. These patterns were used to calibrate the images of 352 original soil samples obtained from smartphones in three different lighting environments - L1 (100–2000 lx), L2 (35,000–40,000 lx), and L3 (75,000–80,000 lx). Random forest models were used to construct predictive models of soil organic matter (SOM) content based on images. Our findings indicate that smartphones exhibit complex spectral response characteristics, which result in poor image accuracy and stability of uncalibrated (C0) images under varying lighting conditions. The uncalibrated (C0) soil images in different lighting environments exhibited high colour difference (∆Emean = 14.11), resulting in poor SOM model sharing performance (R2mean = 0.52 and RMSEmean = 20.33 g/kg). The use of colour calibration methods reduced the colour difference between soil images (∆Emean = 8.19) and improved the shared accuracy of the model (R2mean = 0.61 and RMSEmean = 12.00 g/kg). The pattern of colour calibration has a key impact on the performance of the model application. The model sharing accuracy was found to be higher for the same or similar colour calibration pattern combination compared to different combinations of colour calibration patterns. Overall, the richer the colour calibration blocks, the better the model's shared performance. The findings of this research can enhance the application performance of soil attribute prediction models based on the colour of objects captured by smartphones in natural environments.
94. 题目: Short-term carbon cycling at a Sphagnum farming site under drought stress
Paludiculture is a new land use option for degraded peatlands, producing biomass under wet and peat preserving conditions. While previous studies indicate a significant greenhouse gas mitigation potential, the impact of bryophyte and vascular plant species on carbon cycling is not yet fully understood, especially under drought stress and climate warming conditions. In July 2018, we conducted a pulse labelling experiment at a Sphagnum farming area in Northwestern Germany to trace sequestered carbon dioxide (13CO2) in above-ground biomasses of peat mosses (Sphagnum) and dominant vascular plant species purple moor grass (Molinia caerulea), soil microbial biomass (Cmic), dissolved organic carbon (DOC), as well as dissolved and emitted CO2 and methane under drought stress induced by summer drought and simulated climate warming using Open Top Chambers (OTCs). We observed fast label allocation to all investigated carbon pools with the exception of DOC. Although label uptake was clearly higher in Molinia compared to Sphagnum, most carbon was lost via respiration within a few days and the percentage of stored carbon after 140 days was clearly higher in Sphagnum and Cmic. Differences between warmed and control plots were small, presumably due to the already hot and dry conditions. Our results highlight that carbon uptake and storage processes are maintained even under extreme drought conditions, while further experimental warming using OTCs was less influential. The presented findings confirm the important role of Sphagnum in carbon retention and the risk of methane emissions even at low water levels via plant-mediated transport. Consequently, an elaborate irrigation management and control of vascular plants are the key to successful Sphagnum farming and GHG mitigation.
95. 题目: Magnetic biochar accelerates microbial succession and enhances assimilatory nitrate reduction during pig manure composting
Biochar promotes microbial metabolic activities and reduces N2O on aerobic composting. However, the effects of magnetic biochar (MBC) on the microbial succession and N2O emissions during pig manure composting remain unclear. Herein, a 42-day composting experiment was conducted with five treatment regimes: pig manure without biochar (CK), 5% pig manure-based biochar (5% PBC), 2% MBC (2% MBC), 5% MBC (5% MBC) and 7.5% MBC (7.5% MBC)), to clarify the variation in functional microorganisms and genes associated with nitrogen and direct interspecies electron transfer via metagenomics. Fourier-transform infrared spectroscopy showed that MBC possessed more stable aromatic structures than pig manure-based biochar (PBC), indicating its greater potential for nitrous oxide reduction. MBC treatments were more effective in composting organic matter and improving the carbon/nitrogen ratio than PBC. The microbial composition during composting varied significantly, with the dominant phyla shifting from Firmicutes to Proteobacteria, Actinobacteria, and Bacteroidota. Network and hierarchical clustering analyses showed that the MBC treatment enhanced the interactions of dominant microbes (Proteobacteria and Bacteroidota) and accelerated the composting process. The biochar addition accelerated assimilatory nitrate reduction and slowed dissimilatory nitrate reduction and denitrification. The Mantel test demonstrated that magnetic biochar potentially helped regulate composting nutrients and affected functional nitrogen genes. These findings shed light on the role of MBC in mitigating greenhouse gas emissions during aerobic composting.
96. 题目: Engineered biochar supported bismuth tungstate: Unveiling the influence of precursor concentrations and biochar dosage for the solar photocatalysis of 1,3-diphenylguanidine in secondary municipal effluent
In this work, engineered hierarchal structures of biochar-supported bismuth tungstate are synthesized for wastewater treatment applications. The integration of biochar supports resulted in an increase in the surface area, reduction in crystallite size, and exposure of the active facets of Bi2WO6. Controlled Bi2WO6 morphologies were obtained by varying the precursor concentrations, causing a remarkable transition from mixed microspheres to flower-like structures and, ultimately, to nanosheets. The optimal composite demonstrated its efficiency in a spiked wastewater secondary effluent, achieving 97.74 % degradation of 1,3-diphenylguanidine (DPG) under 8 h of simulated solar light irradiation. The treatment also reduced the toxicity and COD of the spiked secondary effluent matrix. The primary reactive oxygen species detected were O2•– and h+. Additionally, the photocatalytic degradation mechanism and possible degradation by-products of DPG were identified. These results highlight the significant influence of the biochar supports and synthesis parameters on the activity of biochar-supported photocatalysts, paving the way for the design of superior photocatalyst materials for wastewater treatment applications.
97. 题目: Global warming potential assessment under reclaimed water and livestock wastewater irrigation coupled with co-application of inhibitors and biochar
The application of nitrification inhibitors (nitrapyrin) and urease inhibitors (N-(N-butyl) thiophosphoric triamide) under conventional water resources has been considered as an effective means to improve nitrogen utilization efficiency and mitigate soil greenhouse gas emissions. However, it is not known whether the inhibitors still have an inhibitory effect under unconventional water resources (reclaimed water and livestock wastewater) irrigation and whether their use in combination with biochar improves the mitigation effect. Therefore, unconventional water resources were used for irrigation, with groundwater (GW) control. Nitrapyrin and N-(N-butyl) thiophosphoric triamide were used alone or in combination with biochar in a pot experiment, and CO2, N2O, and CH4 emissions were measured. The results showed that irrigation of unconventional water resources exacerbated global warming potential (GWP). All exogenous substance treatments increased CO2 and CH4 emissions and suppressed N2O emissions, independent of the type of water, compared to no substances (NS). The inhibitors were ineffective in reducing the GWP whether or not in combination with biochar, and the combined application of inhibitors with biochar further increased the GWP. This study suggests that using inhibitors and biochar in combination to regulate the greenhouse effect under unconventional water resources irrigation should be done with caution.
98. 题目: Estuarine hydrodynamic processes driving the molecular changes of terrestrial dissolved organic nitrogen: From mixing to biological modification
Estuaries receive substantial amounts of terrestrial dissolved organic nitrogen (tDON), which will be transported from the freshwater to the oceanic terminus through vigorous exchange processes. However, the intricate migration and transformation dynamics of tDON during this transportation, particularly at a molecular level, remain constrained. To address this knowledge gap, Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was used for the analysis of DON molecular composition in the Pearl River Estuary (PRE), a river-dominated estuarine system influenced by intensified anthropogenic activities in southern China. The results showed a pronounced spatial-temporal variation in DON concentration in the study area. At the molecular level, tDON exhibited reduced unsaturation and aromaticity, coupled with an elevated abundance of DON compounds containing one‑nitrogen atom (1 N-DON, 53.17 %) and compounds containing carbon, hydrogen, oxygen, nitrogen, and sulfur (CHONS) (27.46 %). It was evident that lignin was depleted while more oxygenated tannin compounds were generated in the freshwater-seawater mixing zone. This transformation is attributed to heightened biological activities, likely influenced by the priming effect of terrestrial nutrient inputs. In summer, the prevailing plume combined with biological activities in the strong mixing area and outer estuary increased the abundance of 3 N-DON molecules and a concurrent rise in the abundance of DON compounds containing only carbon, hydrogen, oxygen, and nitrogen (CHON), DON compounds containing carbon, hydrogen, oxygen, nitrogen, sulfur, and phosphorus (CHONSP), and CHONS. This trend also underscores the expanding role of marine plankton and microbes in the utilization of DON compounds containing carbon, hydrogen, oxygen, nitrogen, and phosphorus (CHONP). These findings provide details of tDON transformation processes at the molecular level in a river-dominated estuary and underline the estuarine hydrodynamics involved in transporting and altering DON within the estuary.
99. 题目: Enhancing methane production and interspecies electron transfer of anaerobic granular sludge by the immobilization of magnetic biochar
Supplementation of conductive materials has been proved to be a promising approach for enhancing microbial interspecies electron transfer (IET) in anaerobic digestion systems. In this study, magnetic bamboo-based biochar was prepared at temperatures of 400–800 °C via a ball milling/carbonization method, and it immobilized in mature anaerobic granular sludge (AGS) aimed to enhance methane production by improving the IET process between syntrophic microbial communities in the AGS. Results showed that the AGS with magnetic biochar immobilization of demonstrated increased glucotrophic and acetotrophic methane production by 69.54–77.56 % and 39.96–54.92 %, respectively. Magnetic biochar prepared at 800 °C with a relatively higher Fe content (0.37 g/g magnetic biochar) displayed a stronger electron charge/discharge capacity (36.66 F/g), and its immobilization into AGS promoted methane production most. The conductivity of AGS increased by 52.13–87.32 % after incorporating magnetic biochar. Furthermore, the extracellular polymeric substance (EPS) of AGS showed an increased capacitance and decreased electron transfer resistance possibly due to the binding of magnetic biochar and more riboflavin secretion in EPS, which could contribute to the accelerated IET process in the inner AGS. In addition, the immobilization of magnetic biochar could promote the production of volatile fatty acids by 15.36–22.50 %. All these improvements may jointly lead to the enhanced methane production capacity of AGS. This study provided a fundamental understanding of the role of incorporated magnetic biochar in AGS in promoting anaerobic digestion performance.
100. 题目: Microbial mechanisms regulate soil organic carbon mineralization under carbon with varying levels of nitrogen addition in the above-treeline ecosystem
Climate change is leading to the upward migration of treelines in mountainous regions, resulting in changes to the carbon and nitrogen inputs in soils. The impact of these alterations on the microbial mineralization of the existing soil organic carbon (SOC) pool remains uncertain, making it challenging to anticipate their effects on the carbon balance. To enhance our prediction and understanding of native SOC mineralization in Himalayan regions resulting from treeline shifts, a study was conducted to quantify soil priming effects (PEs) at high elevations above the treeline ecosystem. In laboratory incubation, soils were treated with a combination of 13C-glucose and varying nitrogen rates, along with carbon-only treatments and control groups without any amendments. The addition of carbon with varying nitrogen addition rates exhibited diverse PEs on native SOC. A highly positive PE was observed under low nitrogen input due to a high carbon/nitrogen imbalance and increased L-leucine aminopeptidase (LAP) activity, coupled with low nitrogen availability and carbon use efficiency (CUE). In contrast, a positive PE declined following high nitrogen input due to a low carbon/nitrogen imbalance and LAP activity, coupled with high nitrogen availability and CUE. These findings support the concept that multiple mechanisms (i.e., microbial nitrogen mining and microbial metabolic efficiency) exist that regulate SOC mineralization under the addition of carbon with varying nitrogen rates. Thus, an increase in nitrogen availability fulfils microbial nitrogen demand, reduces the microbial carbon/nitrogen imbalance, decreases enzyme activity that requires nitrogen and enhances microbial metabolic efficiency. Consequently, this mechanism reduces the positive PE, thereby serving as a potential tool for stabilizing native SOC in above-treeline ecosystems.