41. 题目: Persulfate-based remediation of organic-contaminated soil: Insight into the impacts of natural iron ions and humic acids with complexation/redox functionality
The use of persulfate (PDS) for in-situ chemical oxidation of organic contaminants in soils has garnered significant interest. However, the presence of naturally occurring iron-containing substances and humic acid (HA) in environmental compartments can potentially influence the effectiveness of soil remediation. Thus, this study aimed to investigate the role of key functional groups (adjacent phenolic hydroxyl (Ar-OH) and carboxyl groups (-COOH)) in HA that interact with iron. Modified HAs were used to confirm the significance of these moieties in iron interaction. Additionally, the mechanism by which specific functional groups affect Fe complexation and redox was explored through contaminant degradation experiments, pH-dependent investigations, HA by-products analysis, and theoretical calculations using six specific hydroxybenzoic acids as HA model compounds. The results showed a strong positive correlation between accessible Ar-OH and -COOH groups and Fe3+/Fe2+ redox. This was attributed to HA undergoing a conversion process to a semiquinone-containing radical form, followed by a quinone-containing intermediate, while Fe3+ acted as an electron shuttle between HA and PDS, with Fe3+ leaching facilitated by generated H+ ions. Although the stability of HA-Fe3+ complexes with -COOH as the primary binding sites was slightly higher at neutral/alkaline conditions compared to acidic conditions, the buffering properties of the soil and acidification of the PDS solution played a greater role in determining the Ar-OH groups as the primary binding site in most cases. Therefore, the availability of Ar-OH groups on HA created a trade-off between accelerated Fe3+/Fe2+ redox and quenching reactions. Appropriate HA and iron contents were found to favor PDS activation, while excessive HA could lead to intense competition for reactive oxygen species (ROS), inhibiting pollutant degradation in soil. The findings provide valuable insights into the interaction of HA and Fe-containing substances in persulfate oxidation, offering useful information for the development of in-situ remediation strategies for organic-contaminated soil.
42. 题目: Molecular comparison of organic matter removal from shale gas flowback wastewater: Ozonation versus Fenton process
Shale gas extraction process generates a large amount of shale gas flowback wastewater (SGFW) containing refractory organic compounds, which can pose serious environmental threats if not properly treated. However, the extremely complex compositions of organics in SGFW are still unknown and their transformation pathways in O3- and •OH-dominated systems are not well recognized, which restrain the selection of treatment technology and optimization of operational parameters. The removal characteristics and reaction mechanism of dissolved organic matter (DOM) in SGFW treated by ozonation and Fenton processes were comparatively investigated using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. The results showed that both processes could degrade low-oxygen highly unsaturated and phenolic organics, polyphenolics and polycyclic aromatics, and transform them into aliphatic organics and high-oxygen highly unsaturated and phenolic organics. With increasing action of reactive oxygen species (O3 for ozonation and •OH for Fenton process), the degradation products (mainly aliphatic organics) increased during ozonation. However, in Fenton process, a wider range of DOM was removed without aliphatic organics accumulation. The degradation mechanisms of DOM during ozonation and Fenton processes included oxygen addition reactions (+3O, +H2O2, and +2O) as dominant pathways. However, ozonation showed more violent oxygenation, hydroxylation, and carboxylation, while Fenton process presented more violent chain-breaking reactions. These results revealed the selective oxidation of ozone and nonselective oxidation of •OH during SGFW treatment, and provided theoretical support for selecting SGFW treatment approaches.
43. 题目: Biochar supported nano core-shell (TiO2/CoFe2O4) for wastewater treatment
The porous structure of biochar, its large surface area, and its anti-oxidant properties are extensively used for pollutant removal strategies. The literature to date has reported that the biochar assisted metal-oxide core-shells have a dominating degradation ability under solar irradiation. Therefore, this study is significantly focused on cinnamon biochar as an active anti-oxidant agent incorporated in titania-cobalt ferrite nanocore-shell (Biochar/TiO2/CoFe2O4) structures for the first time in wastewater treatment against chlorophenol pollutants. Pure materials, core-shells, and biochar aided composites were synthesized by chemical methods, and their characteristics were analyzed using various instrumentation techniques. The diffraction outcomes of Biochar/TiO2/CoFe2O4 showed the mixed phases containing biochar, TiO2, and CoFe2O4. The morphological characteristics revealed that the biochar creates porosity and a peripheral layer covering the core-shell. Meanwhile, absorption studies of TiO2/CoFe2O4 core-shell and Biochar/TiO2/CoFe2O4 samples achieved 65% and 92% degradation efficiencies when exposed to visible light against chlorophenol pollutants, respectively. All these results confirm the presence of distinct functional groups as well as the combined synergistic effects that activated the charge separation, resulting in the successful destruction of water pollutants. In addition, the highly efficient Biochar/TiO2/CoFe2O4 sample was recycled, and the efficiency was maintained stable for five repeated degradation processes. Thus, Biochar/TiO2/CoFe2O4 will be utilized to expand the possibilities for biofuel generation and energy storage devices.
44. 题目: Enhanced membrane fouling by microplastics during nanofiltration of secondary effluent considering secretion, interaction and deposition of extracellular polymeric substances
Microplastic (MP) has been found to influence membrane fouling during microfiltration/ultrafiltration processes in direct and indirect ways by acting as fouling components and changing microbial activities, respectively. However, there are no relevant research about the contribution of MPs to nanofiltration membrane fouling. In this study, for the first time, the impacts of MPs on membrane fouling during the nanofiltration of secondary effluent (SE) were systematically investigated from the perspective of bacterial extracellular polymeric substances (EPS) secretion, their interaction with coexisting pollutants and also deposition. Membrane flux behaviors indicate that MPs simultaneously aggravated the short-term and long-term membrane fouling resistance of nanofiltration by 46 % and 27 %, respectively. ATR-FTIR, XPS and spectrophotometry spectra demonstrate that the deteriorated membrane fouling by MPs directly resulted from the increased accumulation of protein-like, polysaccharides-like and humic-like substances on membranes. EEM spectra further confirmed that MPs preferred to induce serious cake layers, which dominated membrane flux decline but hindered pore fouling. According to CLSM and SEM-EDS mappings, MPs in SE could stimulate microbial activities and then aggravate EPS secretion, after which their interaction with Ca2+ was also enhanced in bulk solution. The cross-linker nets could promote the deposition of other unlinked pollutants on membranes. Besides, MPs could weaken the rejection of certain dissolved organic matters (from 57 % to 52 % on the 50th day of filtration) by aggravating cake-enhanced concentration polarization (CECP), but improved the average removal of inorganic salts from 58 % to 63 % by improving their back diffusion through cake layers. Based on these analyses, the mechanisms of MP-enhanced membrane fouling during the nanofiltration of SE can be thoroughly revealed.
45. 题目: Mitigation of soil N2O emissions by decomposed straw based on changes in dissolved organic matter and denitrifying bacteria
The return of decomposed straw represents a less explored potential option for reducing N2O emissions. However, the mechanisms underlying the effects of decomposed straw return on soil N2O mitigation are still not fully clear. Therefore, we used a helium atmosphere robotized continuous flow incubation system to compare the soil N2O and N2 emissions from four treatments: CK (control: no straw), WS (wheat straw), IWS (wheat straw decomposed with Irpex lacteus), and PWS (wheat straw decomposed with Phanerochaete chrysosporium). All the treatments have been fertilized with the same amount of KNO3. Furthermore, we also analyzed i) the chemodiversity of soil dissolved organic matter (DOM), ii) the nirS, nirK, and nosZ gene copies and relative abundances of denitrifying bacterial communities (DBCs), and iii) the specific linkages between N2O emissions and DOM and DBC. The results showed that the WS, IWS and PWS treatments increased N2O emissions compared to the CK treatment. However, applying decomposed straw to soil, especially straw treated with P. chrysosporium, effectively decreased the soil N2O and increased N2 emissions compared to WS and IWS. Moreover, the IWS and PWS treatments increased the CHO composition, but they decreased the CHON and CHOS compositions of heteroatomic compounds of DOM compared with the WS and CK treatments. Furthermore, the WS, IWS and PWS treatments all significantly increased the nirS and nosZ gene copies compared with the CK treatment. Additionally, compared with the other treatments, the PWS treatment significantly shaped the DBC and led to a higher relative abundance of Pseudomonas with nirS and nosZ genes. Meanwhile, Network analysis showed that the mitigation of N2O was closely related to particular DOM molecules, and specific DBC taxa. These results highlight the potential for decomposed straw amendments to mitigate of soil N2O emissions not only by changing soil DOM but also mediating the soil DBC.
46. 题目: Compositional and spectroscopic analysis of dissolved organic matter samples from Everglades periphyton and water
Periphyton is a ubiquitous niche in aquatic environments and can be a significant source of dissolved organic matter (DOM) production and leaching, especially in such environment as the Everglades, a slow-water flow wetland in Florida, USA. We employed an array of methods, including compositional analysis, 3-dimensional excitation emission matrix (3-D EEM) fluorescence spectroscopy, and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, to perform quantitative and qualitative analyses on the DOM produced by periphyton and DOM in surrounding surface water and periphyton overlying water for comparison purposes. Higher dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) contents in periphyton pore water than surface water and periphyton overlying water indicated the remarkable contribution from periphyton-produced DOM. Higher total protein, carbohydrate, and thiol contents in periphyton pore water than in surface water and periphyton overlying water underscored the possibility of periphyton pore water DOM leached from periphyton. These results agreed with 3-D EEM and ATR-FTIR analyses that showed the prevalence of possible microbial source of periphyton pore water DOM as indicated by higher fluorescence index (FI) than surface water and periphyton overlying water. Similarly, the size-fractionated DOM from surface water demonstrated terrestrial sources, and periphyton pore water demonstrated microbial sources regardless of their differences in size based on their FI values. The types of periphyton affect the production and composition of DOM, as evidenced by higher total protein, carbohydrate, and chlorophyll-a (Chl-a) contents in floating mat on the water surface than in epiphyton attached to submerged phytoplankton, probably because the former is photo-synthetically more productive than the latter due to different light availability. This study provided fundamental information on periphyton DOM that is essential for further investigating its role in carbon cycle and its biogeochemistry.
47. 题目: Biochar addition reduces N2O emissions in fertilized soils under energy cane cultivation
N2O emissions resulting from the application of nitrogen (N) fertilizers and vinasse represent the main sources of greenhouse gases (GHG) emissions in sugar-energy sector. Conversely, the application of biochar in soils has been worldwide recognized as an strategy to mitigate N2O emissions, although little is known about their effects on soils under energy cane production. The study aimed to evaluate the effects of biochar addition as a strategy to mitigate soil N2O emissions in soil under energy cane cultivation, as well as to quantify the abundance of N2O-producing and N2O-reducing microbial guilds. A greenhouse experiment was conducted in a completely randomized design, with five treatments and four replications. The treatments were: i) no N fertilization (control); ii) N fertilization; iii) N fertilization plus vinasse; iv) N fertilization plus biochar; v) N fertilization plus vinasse plus biochar. All treatments (except control) were balanced to receive the same amount of nutrients. Biochar was added at a rate of 5 g kg−1 of soil. Soil N2O emissions were quantified by static chambers for 78 days, and soil sampling were performed to determine chemical and microbiological attributes, including functional genes of the nitrogen cycle (AOA, AOB, nirK, nirS, nosZI and nosZII) by real-time PCR. Results indicated that vinasse addition increased N2O emissions. Conversely, the application of biochar reduced N2O emissions associated with the application of N fertilizer (56 %) and N fertilizer + vinasse (41 %). The high N2O emissions observed in vinasse treatment were directly correlated with nitrifier microorganisms (AOB and AOA), indicating that nitrification should be the main pathway of N2O emissions in this treatment. The production of energy cane biomass was similar between N fertilizer treatments. High N2O emission intensities (mg N2O g biomass−1) were obtained in treatments with vinasse application. This study concluded that biochar is an effficient strategy to mitigate N2O emissions, providing the first insights into how biochar affects the microbial community associated with N2O emissions from soil under energy cane cultivation.
48. 题目: Expanding the Limits of Structural Characterization of Marine Dissolved Organic Matter Using Nonuniform Sampling Frequency-Reversed Edited HSQC NMR
49. 题目: Effects of ferrous sulfate modification on the fate of phosphorous in sewage sludge biochar and its releasing mechanisms in heavy metal contaminated soils
Modifications of sludge biochar with metal-based materials can enhance its fertilizing efficiency and improve safety. To elucidate the effects of ferrous sulfate modification on the fate of phosphorus in sludge biochar and its effect on phosphorus fractionation in soil, we investigated the changes in fractionation and bioavailability of phosphorus in modified sludge biochar and studied the changes in soil characteristics, microbial diversity and response, bioavailability, plant uptake of phosphorus, and heavy metals in contaminated soils after treatment with ferrous sulfate modified sludge biochar. The results demonstrated that ferrous sulfate modifications were conducive to the formation of moderately labile phosphorus in sludge biochar, and the concentrations increased by a factor of 2.7 compared to control. The application of ferrous sulfate-modified sludge biochar to alkaline heavy metal-contaminated soils enhanced the bioavailable, labile, and moderately labile phosphorus contents by a factor of 2.9, 3.0, and 1.6, respectively, whereas it obviously reduced the leachability and bioavailability of heavy metals in soils, exhibited great potentials in the fertilization and remediation of actual heavy metal-contaminated soils in mining areas. The biochar-induced reduction in soil pH, enhancement of organic matter, surface oxygen-containing functional groups, the abundance of Gammaproteobacteria, and its phosphonate degradation activity were primarily responsible for the solubilization of phosphorus from modified biochar in heavy metal-contaminated soils.
50. 题目: High rates of rock organic carbon oxidation sustained as Andean sediment transits the Amazon foreland-floodplain
51. 题目: Mechanisms shaping dissolved organic matter and microbial community in lake ecosystems
Lakes are active components of the global carbon cycle and host a range of processes that degrade and modify dissolved organic matter (DOM). Through the degradation of DOM molecules and the synthesis of new compounds, microbes in aquatic environments strongly and continuously influence chemodiversity, which can feedback to influence microbial diversity. Developing a better understanding of the biodiversity patterns that emerge along spatial and environmental gradients is one of the key objectives of community ecology. A changing climate may affect ecological feedback, including those that affect microbial communities. To maintain the function of a lake ecosystem and predict carbon cycling in the environment, it is increasingly important to understand the coupling between microbial and DOM diversity. To unravel the biotic and abiotic mechanisms that control the structure and patterns of DOM and microbial communities in lakes, we combined high-throughput sequencing and ultra-high resolution mass spectrometry together with a null modeling approach. The advantage of null models is their ability to evaluate the relative influences of stochastic and deterministic assembly processes in both DOM and microbial community assemblages. The present study includes spatiotemporal signatures of DOM and the microbial community in six temperate lakes contrasting continental and Mediterranean climates during the productive season. Different environmental conditions and nutrient sources characterized the studied lakes. Our results have shown high covariance between molecular-level DOM diversity and the diversity of individual microbial communities especially with diversity of microeukaryotes and free-living bacteria indicating their dynamic feedback. We found that the differences between lakes and climatic regions were mainly reflected in the diversity of DOM at the molecular formula-level and the microeukaryota community. Furthermore, using null models the DOM assembly was governed by deterministic variable selection operating consistently and strongly within and among lakes. In contrast, microbial community assembly processes were highly variable across lakes with different trophic status and climatic regions. Difference in the processes governing DOM and microbial composition does not indicate weak coupling between these components, rather it suggests that distinct factors may be influencing microbial communities and DOM assemblages separately. Further understanding of the DOM-microbe coupling (or lack thereof) is key to formulating predictive models of future lake ecology and function.
52. 题目: Biochar inoculated with Pseudomonas putida alleviates its inhibitory effect on biodegradation pathways in phenanthrene-contaminated soil
Controversial results are reported whereby biodegradation of polycyclic aromatic hydrocarbons (PAHs) can be promoted or inhibited by biochar amendment of soil. Metabolomics was applied to analyze the metabolic profiles of amendment with biochar (BB) and biochar inoculated with functional bacteria (Pseudomonas putida) (BP) involved in phenanthrene (PHE) degradation. Additionally, metagenomic analysis was utilized to assess the impact of different treatments on PHE degradation by soil microorganisms. Results indicated that BB treatment decreased the PHE biodegradation of the soil indigenous bacterial consortium, but BP treatment alleviated this inhibitory effect. Metabolomics revealed the differential metabolite 9-phenanthrol was absent in the BB treatment, but was found in the control group (CK), and in the treatment inoculated with the Pseudomonas putida (Ps) and the BP treatment. Metagenomic analysis showed that biochar decreased the abundance of the cytochrome P450 monooxygenase (CYP116), which was detected in the Pseudomonas putida, thus alleviating the inhibitory effect of biochar on PHE degradation. Moreover, a noticeable delayed increase of functional gene abundance and enzymes abundance in the BB treatment was observed in the PHE degradation pathway. Our findings elucidate the mechanism of inhibition with biochar amendment and the alleviating effect of biochar inoculated with degrading bacteria.
53. 题目: Impacts of biochar derived from oil sludge on anaerobic digestion of sewage sludge: Performance and associated mechanisms
The addition of biochar is a promising strategy to improve methane production via strengthening direct interspecies electron transfer (DIET) in anaerobic digestion (AD) field. In this study, a novel oil sludge biochar (OSBC) prepared at 500/600/700 °C was used to investigate its dosage effects on performances of sewage sludge AD. The characterization results indicated that OSBC prepared at 600 °C had highest electron accepting and donating capacity, meanwhile, it also contained moderate functional groups such as CO, which were in favor of methane production. Therefore, the highest accumulative methane yield (143.96 mL (g VS)−1) accompanying with the fast consumption of volatile fatty acids (VFAs) was achieved at dosage of 1.2 g. Additionally, the conductivity and enzyme activity (electron transport system activity and coenzyme F420) of AD with OSBC addition were also enhanced. Microbial community structures manifested that the potential syntrophic microbes including archaea Methanothrix, Methanospirillum, and bacteria Comamonas, Petrimonas and Syntrophomonas were enriched by OSBC due to its large surface area and microelement such as iron, and contributed to the improved methane production. The results suggested that OSBC exhibited excellent practical application potential in enhancing anaerobic sewage sludge treatment and biogas productivity.
54. 题目: Electrochemical oxidation treatment of reverse osmosis concentrated landfill leachate: Effect of operation parameters and evolution of dissolved organic matter
Electrochemical oxidation (EO) is a viable option for the advanced treatment of reverse osmosis concentrated landfill leachate (ROCLL). This work characterized dissolved organic matter (DOM) in ROCLL with size exclusion chromatography (SEC) and then investigated the impact of operating parameters on the removal of DOM fractions with response surface methodology (RSM). The SEC chromatograms revealed that the DOM fractions in ROCLL comprised of biopolymers (BP, > 18 kDa), humic substances (HS, 0.45–18 kDa) and low molecular weight substances (LMWS, < 0.45 kDa). For the EO configuration with different anodes, the BDD film anode showed the highest removal efficiency for DOM in terms of COD, DOC, UVA254 and fluorescence indices, followed by Ti, graphite, Ti/RuO2-IrO2 and Ti/SnO2-Sb2O5 anodes. The RSM experiments suggested that pH was the most critical factor to enhance the removal of all DOM fractions, and acidification pretreatment could remove approximately 50% BP and 30% HS fractions due to the pH-induced precipitation. The DOC removal kinetics of DOM fractions could be described by pseudo-zero kinetic model with rates in the order of HS > LMWS > BP, which were controlled by charge transfer process. Differently, the elimination of chromophores and fluorophores followed pseudo-first kinetics, which was limited by mass transport process. Via nonnegativity matrix factorization (NMF) deconvolution of the SEC-OCD chromatograms, BP-C1, HS-C2 and LMWS-C1 subfractions required to be removed through further treatment after EO process. This work demonstrates the potential for SEC analysis coupled with mathematical approaches to give informative insights into the evolution of DOM and provide optimization strategies for the EO treatment of complex ROCLL.
55. 题目: Enhanced adsorption of roxarsone on iron–nitrogen co-doped biochar from peanut shell: Synthesis, performance and mechanism
Efficient removal of organic arsenic (roxarsone, ROX) from wastewater is highly demanded on the purpose of human health and environmental protection. This work aims to prepare Fe-N- co-doped biochar (Fe-N-BC) via one-pot hydrothermal method using waste peanut shell, FeCl3·6H2O and urea, followed by pyrolysis. The effect of Fe-N co-doping on biochar's physicochemical properties, and adsorption performance for ROX were systematically investigated. At the pyrolysis temperature of 650 °C, Fe-N-BC-650 shows a significantly increased specific surface area of 358.53 m2/g with well-developed micro-mesoporous structure. Its adsorption capacity reaches as high as 197.32 mg/g at 25 °C, with > 90 % regeneration efficiency after multiple adsorption–desorption cycles. Correlation and spectral analysis revealed that the pore filling, π-π interactions, as well as hydrogen bonding play the dominant role in ROX adsorption. These results suggest that the Fe-N co-doped biochar shows great potential in the ROX removal from wastewater with high efficiency.
56. 题目: Insight into the effect of particulate organic matter on sludge granulation at the low organic load: Sludge characteristics, extracellular polymeric substances and microbial communities response
This paper investigated the effect of particulate organic matter (POM) on sludge granulation under low organic load. The results showed that POM promoted the formation of aerobic granular sludge (AGS) with a chemical oxygen demand (COD) fraction of 25%, and POM also enhanced the sludge settleability and biomass retention. However, when the COD fraction of POM increased to 50% and 75%, the AGS performance deteriorated. The analysis of extracellular polymeric substances revealed that the POM (accounted for ≤ 50% of COD in the influent) suppressed the secretion of extracellular protein. Analysis of the microbial community showed that species diversity was lower in the POM-fed system, with Rhodocyclaceae being the predominant bacteria responsible for carbon source degradation. Additionally, molecular ecological network analysis demonstrated that when the COD fraction of the POM exceeded 50%, the connectivity and modularity between microbial species decreased, which may explain the sludge performance deterioration.
57. 题目: Forest harvesting affects soil organic carbon and total nitrogen transports by facilitating landslides
Landslides considerably affect soil organic carbon (SOC) and total nitrogen (TN) transports. However, the quantitative assessment of these effects remain limited. Furthermore, it is unresolved how forestry practices, especially clearcutting and subsequent planting, affect the SOC and TN transports by facilitating landslides. Therefore, we quantified the SOC and TN transports attributable to landslides from 1948 to 2012 in a steep mountainous area in Japan and examined the impacts of forest clearcutting on SOC and TN transports through landslides. We used 12 aerial photographs and two LiDAR DEMs to identify the landslide areas and to estimate their scar depths. In addition, we sampled soil at 17 points to examine the relationship between SOC and TN and soil depth. Subsequently, we estimated the temporal changes in SOC and TN transports due to landslides and examined the relationships between forest age and rates of SOC or TN transport due to landslides. During the 64 years, the average annual rate of landslide was 3.7 × 10−2 ha km−2 yr−1. Large temporal variability existed in rates of landslide, and the maximum rate of landslide was around 11.0 × 10−2 ha km−2 yr−1, while almost no landslide occurred in some periods. The average annual SOC and TN transport rates were 5.8–9.3 MgC km−2 yr−1 and 0.5–0.9 MgN km−2 yr−1, respectively. Many landslides occurred at places where trees were 15 years old or less in plated forests. The amount of SOC and TN transports in landslide areas with < 20 forest age accounted for 87% of the total amounts moved owing to landslides. That is, our results clearly showed that forest harvesting increased landslide frequency and SOC and TN transport rates. We expect our results to be useful for predicting carbon stock in forest ecosystems and optimizing forestry practices in steep mountainous regions.
58. 题目: Recalcitrant organic carbon plays a key role in soil carbon sequestration along a long-term vegetation succession on the Loess Plateau
Vegetation restoration effectively promotes soil quality and enhances soil organic carbon (SOC) sequestration. However, the dynamics and driving factors of SOC fractions during long-term vegetation succession remain unclear. In this study, a complete ∼ 160 years successional chronosequence from farmland to climax forest was used to study the dynamics and driving factors of SOC fractions in topsoil (0–20 cm) and subsoil (20–40 cm). The results showed that vegetation succession age significantly affected the SOC and its fractions (p < 0.05). The content of SOC fractions increased with succession age, especially recalcitrant organic carbon (ROC), which accounted for 62%–85% of the total SOC. Long-term vegetation succession enhanced the stability of SOC pools, reduced the proportion of active C, and facilitated the fixation of C. ROC was the best indicator of SOC accumulation within the entire profile. When vegetation succession reached the pioneer forest stage (∼110 years), the SOC content and fractions increased significantly (p < 0.05) owing to continuous plant biomass inputs. Moreover, soil C sequestration was controlled by total nitrogen content in the topsoil and by belowground biomass in the subsoil. This study indicates that long-term vegetation succession can effectively improve SOC accumulation and SOC pool quality, emphasizing the need to focus on SOC pool stabilization mechanisms under future climate change.
59. 题目: The combined effects of nitrogen fertilizer and biochar on soil aggregation, N2O emission, and yield from a vegetable field in southeastern China
Biochar amendment is a recently promoted agricultural management strategy that can exert distinct impacts on reducing greenhouse gas (GHG) emissions and improving soil fertility and crop productivity. This study aims to evaluate the combined effects of biochar and nitrogen (N) fertilizer on soil aggregation, nitrous oxide (N2O) emission, global warming potential (GWP), vegetable yield, and greenhouse gas intensity (GHGI). The experiments were conducted in a vegetable field with two consecutive vegetable crops in 2019 and 2020 in southeastern China. There were four treatments: control (CK), conventional N fertilizer (U), biochar applied at 15 t ha−1 with N fertilizer (UB1), and biochar applied at 30 t ha−1 with N fertilizer (UB2). The results indicate that while N application significantly increased N2O emission of the vegetable field, both UB1 and UB2 led to significant reductions of the total N2O emission, GWP, and yield-scaled GHGI as well as significant growth of the total vegetable crop yield compared with U. However, no significant differences have been found in N2O emission, GWP, crop yield, and yield-scaled GHGI between UB1 and UB2. Meanwhile, biochar application in addition to N fertilizer did not result in any significant change in the soil water-stable aggregate size distribution and stability compared with U. Soil water-stable aggregates smaller than 0.25 mm and those larger than 5 mm have been found to significantly impact N2O emission and vegetable yield.
60. 题目: Enhanced Pb(II) removal from wastewater by co-pyrolysis biochar derived from sewage sludge and calcium sulfate: Performance evaluation and quantitative mechanism analysis
Lead (Pb) is a toxic heavy metal posing potential harm to the environment and human health. In this study, Pb(II) adsorption performance of co-pyrolysis biochar derived from sewage sludge and gypsum (CaSO4) was first investigated. The anti-interference to environmental factors was investigated, with the underlying mechanisms being explored quantitatively. The maximum Pb(II) adsorption capacity of co-pyrolysis biochar (SSCB, 152.66 mg/g) was largely improved compared to single sewage sludge biochar (SSB, 29.95 mg/g) at a dosage of 1 g/L and initial pH of 6.0. Model analysis results indicated that monolayer sorption, chemisorption, intraparticle diffusion and endothermic processes were involved in the adsorption process. Among the tested co-existing ions, Fe2+ and NH4+ mostly disrupted the Pb(II) removal. Mineral precipitation (37.55%) and ion exchange (28.05%) were calculated as the major adsorption mechanisms (65.60%) for Pb(II) removal using co-pyrolysis biochar. SSCB showed better reusability for Pb(II) removal in 5 regeneration cycles. This work provides fundamental references for the utilization of solid wastes via co-pyrolysis to biochar for heavy metals removal towards sustainable development.