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41. 题目: The primacy of dissolved organic matter to aquatic light variability
文章编号: N25020913
期刊: Biogeosciences
作者: Henry F Houskeeper, Stanford B Hooker
更新时间: 2025-02-09
摘要: . Absorption and scattering by optically active constituents (OACs) modify the sunlit aquatic light environment, facilitating the derivation of biogeochemical data products at scales spanning in situ to satellite observations. Excluding solar illumination and atmospheric effects, variability in an optical parameter arises from changing OAC concentrations, wherein observed patterns in the spectral evolution of data products are associated with the connectivity and spatiotemporal dynamics of OACs. In open-ocean water masses far from terrestrial and riverine inputs, the content and mixture of OACs principally relates to the dynamics of the microbial loop—a trophic pathway describing the cycling of microbial primary producers (i.e., phytoplankton), remineralizers (e.g., bacteria and archaea), plus dissolved organic and inorganic materials (as applicable). Historical models of open-ocean optical data products, such as the normalized water-leaving radiance, [L_W (λ)]_N, primarily invoke chlorophyll a (C_a)—a commonly used proxy for phytoplankton biomass—as the ubiquitous independent variable governing aquatic light variability. Formulation of [L_W (λ)]_N as a function of C_a content assumes an idealized microbial loop wherein phytoplankton variability modifies other OACs, including the colored (or chromophoric depending on the literature) portion of the dissolved organic matter (DOM) pool, hereafter CDOM. The prescription in which C_a maximally captures oceanic light variability (hereafter primacy) is tested herein using eigen analyses on three independent bio-optical datasets to assess the shapes and associations of the principal and secondary eigenfunctions of aquatic [L_W (λ)]_N observations. The analyses reveal [L_W (λ)]_N variations to be more strongly associated with changes in CDOM than C_a—even for oligotrophic and oceanic datasets—indicating that CDOM dynamics are more variable and exhibit greater independence from C_a than formerly ascribed. Blue and green band-ratio algorithms routinely used for remote sensing of C_a are found to be maximally sensitive to CDOM—rather than C_a—variability based on partial correlation coefficients relating eigenfunction scalar amplitude functions to field or derived observations, plus validation tests of OC algorithm performance. Spectral subset eigen analyses indicate expansive spectral range observing improves the independence in retrieving CDOM absorption and C_a. The combined findings indicate expanded spectral observations supported by recent domestic and international satellite missions constitute a new and unique opportunity to optically characterize surface ocean phytoplankton stocks without relying on explicit or implied empiricisms requiring CDOM and other OACs to vary consistently with C_a. Shapes and associations of the eigen functions suggest a greater diversity of trophic pathways drive OAC dynamics—e.g., in addition to phytoplankton contributing CDOM via cellular lysis, excretion, and grazing—and are consistent with advancing knowledge of the microbial loop in the decades after bio-optical formulations based on C_a were proposed.

42. 题目: Impacts of sugarcane bagasse-derived biochar and apatite on heavy metal speciation in incubated heavy metal-contaminated soil
文章编号: N25020912
期刊: Environmental Science and Pollution Research
作者: Truong Xuan Vuong, Thi Anh Ngoc Vu, Xuan Thang Dam, Viet Cao, Thi Thao Truong, Thi Thu Ha Pham, Thi Tam Khieu, Thi Thu Thuy Nguyen, Thi Kim Ngan Nguyen
更新时间: 2025-02-09
摘要:

Heavy metal contamination in soils poses significant environmental and health risks, necessitating effective remediation strategies. This study investigates the time-dependent effects of sugarcane bagasse-derived biochar and apatite as soil amendments on the chemical speciation of heavy metals in polluted soil. Despite their known efficacy, the specific influence of these amendments on the distribution of heavy metal chemical fractions over time remains underexplored. Incubated experiments were conducted over one month using soil samples spiked with Biochar and apatite. Pb- and Zn-contaminated soils were incubated with biochar and apatite at varying ratios: biochar at 5% and 10%, and biochar/apatite mixtures at 2.5:2.5% and 5:5% ratios (in mass). Changes in heavy metal speciation were analyzed using Tessier’s sequential extraction procedure. Results demonstrate significant shifts in the distribution of heavy metals across soil phases, suggesting potential reductions in bioavailability and environmental mobility. Incubation with varying application rates of biochar and apatite revealed diverse effects on Pb and Zn chemical fractions. Amendments reduced the exchangeable fraction of Pb and Zn by up to 38.5% and 47.7%, respectively, while increasing their more stable F4 and F5 fractions. Proposed mechanisms likely include cation exchange (swapping of ions between the soil and amendments), precipitation (formation of solid compounds), complexation with functional groups/minerals, and physical adsorption (attachment of metal ions) on biochar surfaces The efficacy of biochar and apatite underscores their promise for remediating Pb and Zn in contaminated soils, though variability in efficacy across different soil types warrants further investigation. These findings indicate the potential for practical applications in large-scale soil remediation projects. Further research is needed to assess the persistence of heavy metal stabilization over time and under varying environmental conditions.

43. 题目: The Role of Natural Organic Matter in the Degradation of Phenolic Pollutants by Sulfate Radical Oxidation: Radical Scavenging vs Reduction
文章编号: N25020911
期刊: Environmental Science & Technology
作者: Teng Zhang, Peizeng Yang, Yuefei Ji, Junhe Lu
更新时间: 2025-02-09
摘要: Dissolved natural organic matter (NOM) significantly influences the performance of water treatment processes. It is generally recognized that NOM acts as a radical scavenger, thus inhibiting the degradation of organic pollutants in advanced oxidation processes (AOPs). This study examined the impacts of 8 different NOM isolates on the degradation of 4-chlorophenol (CP), a representative phenolic pollutant, in sulfate radical (SO₄^•–)-based AOPs. We developed an improved probe method to measure the steady-state concentration of SO₄^•– ([SO₄^•–]_ss) in both the absence and presence of NOM. Results show that adding 1.00 mg_C L^–1 NOM resulted in only a 1.3–3.4% decrease in [SO₄^•–]_ss. However, the apparent rate constants of CP degradation decreased by 76–88%. This discrepancy indicates that radical scavenging cannot be the primary mechanism for observed inhibition. We proposed NOM primarily acts as a reducing agent, reacting with the phenoxy radical intermediates generated from the single-electron oxidation of CP by SO₄^•–. Based on this hypothesis, we developed and validated a kinetic model using experimental data. The reductive capacity of NOM, as determined by the kinetic model, correlates positively with its electron-donating capacity. These findings enhance the understanding of NOM’s role in SO₄^•–-based AOPs and provide a foundation for developing strategies to mitigate its adverse effects.

44. 题目: Metabolomic profiling of paper board sludge biochar for agricultural use
文章编号: N25020910
期刊: Environmental Monitoring and Assessment
作者: T Sherene Jenita Rajammal, Vaishnavi Pandurangan, Baskar Murugaiyan, Vanniarajan Chockalingam, S A Ramjani
更新时间: 2025-02-09
摘要:

The pulp and paperboard industries are the major industrial sector that consumes significant amounts of fresh water and generates large volumes of wastewater. The treatment of this wastewater resulted in the production of a substantial amount of sludge, which posed serious environmental challenges. This study explored a sustainable solution by converting PBS into biochar through slow pyrolysis of temperatures up to ≤ 500 °C, offering an alternative approach to waste management and resource conservation. The physicochemical parameters of paper board sludge biochar (PBSB) exhibited a neutral pH of 7.49, electrical conductivity of 0.09 dS m⁻¹, organic carbon of 38.12% and CaCO₃ of 24.5%. Proximate analysis of PBSB revealed an increased fixed carbon of 76.43%, total organic carbon (TOC) of 7.13%, and reduced volatile matter and moisture levels. The TGA analysis of the dried paperboard sludge sample showed a 20% mass reduction when heated to 350 °C. During this process, more than 90% of the volatile components were removed.. The micro nutrients viz., Fe 5.06 mg L⁻¹, Mn 419.3 mg L⁻¹, Cu 26.3 mg L⁻¹, and Zn 66.1 mg L⁻¹ contents were observed in PBSB. FT-IR analysis identified the presence of various carbon-containing functional groups, including C–Cl, C–N, C–C, H–C = O, C–H, and –C≡C–H, indicating substantial chemical transformations during pyrolysis. SEM–EDX analysis revealed that PBSB has fine particle size and a coarse fluffy spongy porous structure ideal for water adsorption. Elemental analysis (XRD) showed high carbon and oxygen content with significant amounts of aluminosilicates, carbonates, and nutrients like phosphorus and potassium, suggesting PBSB as a potential slow-release fertilizer. This research highlights the potential of biochar derived from paperboard waste as a sustainable solution for waste management and resource recovery.

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45. 题目: Geochemical mapping of modern sedimentary organic matter deposited in a World Heritage subtropical estuary affected by human activities: stable isotopes and molecular approaches
文章编号: N25020909
期刊: Environmental Science and Pollution Research
作者: Marines Maria Wilhelm, Ana Caroline Cabral, Felipe Rodrigues dos Santos, Ana Lúcia Lindroth Dauner, Márcia Caruso Bícego, Renata Hanae Nagai, Rubens Cesar Lopes Figueira, Michel Michaelovitch de Mahiques, César de Castro Martins
更新时间: 2025-02-09
摘要:

The Paranaguá Estuarine System (PES) plays a crucial ecological and economic role in the coastal zone of Brazil, containing significant remaining portions of the Atlantic rainforest, which is considered a World Heritage Site (WHS) by UNESCO. At the same time, the PES accommodates the largest bulk grain port terminal and is the leader in container handling in Latin America. In this study, we combined elemental, isotopic, and molecular markers (n-alkanes and n-alkanols) with a comprehensive sample set of surface sediments to understand and distinguish the primary sources of sedimentary organic matter (OM) and evaluate the environmental quality of a WHS under human pressure. The C/N ratio and δ¹³C ranged from 4.98 to 17.9 and − 27.15 to − 22.88‰, respectively. These results suggest that the primary bulk OM origin is the terrigenous contribution from river inputs. The total long-chain n-alkanes and n-alkanols results ranged from 0.29 to 12.3 µg g⁻¹ and 0.19 and 998.1 µg g⁻¹, respectively, and the n-alkanes diagnostic indices (e.g. CPI and TAR) agree with elementary and isotopic proxies. The river contribution, together with tidal currents, dominates the local hydrodynamics. However, the estuarine mouth region and northern sector are strongly influenced by marine-sourced OM. It was also observed that the low-energy estuarine hydrodynamics controls the OM deposition in Antonina Bay, which favours the deposition of fine sediments. In Paranaguá Bay, due to a mixing zone with the intrusion of fresh and marine waters, there are sites of preferential accumulation of OM caused by fine particles’ flocculation. This geochemical mapping of sedimentary OM composition may provide important insights into future scenarios of environmental changes and may be applied to track the deposition and accumulation of anthropogenic residues from the continental basin and port activities.

46. 题目: Simultaneous removal of hardness and organic matter from oilfield-produced water by microbially induced calcite precipitation
文章编号: N25020908
期刊: Water Research
作者: Miao Zhang, Biao Wei, Hao Liu, Daoqing Liu, Geoffrey Michael Gadd, Qianwei Li, Chunmao Chen
更新时间: 2025-02-09
摘要: Oilfield-produced water (PW), the largest by-product of petroleum extraction, presents significant treatment challenges due to high concentrations of total dissolved solids, heavy metals, and organic compounds. In this study, a ureolytic bacterium Staphylococcus succinus J3, with efficient petroleum degradation and microbially induced calcite precipitation (MICP) capabilities, was screened for simultaneous removal of hardness ions and organic pollutants from PW. Strain J3 showed excellent removal of Ca²⁺ (95%), organic contaminants (62%), and heavy metals (100% for As and Mn, 94% for Cu, 71% for Ba) in high salinity PW under low nutrient conditions. Mechanistic analysis revealed that the bacteria removed organic pollutants through biodegradation, and the biominerals generated by MICP further accelerated the removal of organic contaminants through adsorption. Meanwhile, molecular characterization via FT-ICR MS demonstrated the conversion of large organic molecules into smaller, less toxic compounds, facilitating the downstream treatment of PW. Furthermore, the ammonium by-product (NH₄-N) from urea hydrolysis was efficiently recovered (83.73%) as ammonium sulfate for agricultural production through Donnan dialysis (DD). This research presents a promising new approach for the pre-treatment of high-hardness organic wastewater and provides molecular-level insights into the mechanisms of organic matter removal, thus supporting the advancement and optimization of PW recycling technology.

47. 题目: The irreversible transformation of the molecular structure of humic acid during pH change and its effects on the formation of disinfection by-products
文章编号: N25020907
期刊: Journal of Hazardous Materials
作者: Yun Xiao, Yufei Li, Hankun Yang, Sajid Rashid, Nigel Graham, Wenzheng Yu
更新时间: 2025-02-09
摘要: Humic acid (HA) is an important component of natural organic matter, and understanding the nature and environmental behavior of HA is essential for advancing water treatment technologies and environmental remediation strategies. This study investigated the structural differences of HA at various pH values and whether the structure is reversible (whether the structure is similar when HA at different pH values is adjusted back to neutral compared to the original pH 7) by optical characteristics, hydrodynamic volume, fluorescence, infrared and circular dichroism spectroscopy. After adjustment back to neutral, from prior exposure to different pH values (2−12), the results showed an irreversible behavior of HA. For acidified HA restoring neutrality, the TOC and UV₂₅₄ values decreased by 12.2 % and 11.2 %, respectively, and the formation of haloacetic acids (HAAs) and trihalomethanes (THMs) decreased by 24.1 % and 31.5 %, respectively. These changes were attributed to the protonation of oxygenated groups, the weakening of hydrogen bonding, resulting in the formation of aggregates by HA molecules and hydrophilic and hydrophobic structural changes. For alkalized HA restoring neutrality, the TOC increased by 10.7 %, and the formation of HAAs and THMs increased by 16.1 % and 26.2 %, respectively. These changes were attributed to the increase of electronegativity following deprotonation of HA functional groups, molecular swelling caused by increased molecular repulsion, and twisting of the secondary structure. This study provides new insights regarding the effect of changes in pH conditions on the structure and reactivity of HA, which are important for future approaches to the removal of HA and management of disinfection by-products (DBPs) formation in water treatment.

48. 题目: Preparation of a coarse flocculant from concentrated organic matter: Regulation by hydrothermal pretreatment
文章编号: N25020906
期刊: Journal of Environmental Management
作者: Xiao Zha, Shuojun Chen, Yong Huang
更新时间: 2025-02-09
摘要: The process of preparing a flocculant using concentrated organic matter has demonstrated effective results in enriching organic matter in municipal wastewater. The basic preparation process involves a combination of hydrothermal treatment and chemical modification. To enhance the enrichment effect of organic matter, the optimal hydrothermal conditions and their influence on the characteristics of liquid products and coarse flocculant were investigated. The results indicated that liquid products obtained at 140 °C for 30 min yielded a high concentration of active groups and exhibited a significantly higher molecular weight, making them suitable as precursors for the coarse flocculant. When the dosage of the coarse flocculant was set at 10 mg/L, the turbidity removal rate of the kaolin suspension reached 93 %. In the treatment of municipal domestic sewage, a COD removal rate of approximately 62 % was achieved at a dosage of 10 mg/L. Within the experimental range, a decrease in hydrothermal time and temperature favored the production of more reactive groups from the dissolved polymeric substances (DPS), thereby enhancing the charge density of the coarse flocculant. The intrinsic viscosity of the coarse flocculant was influenced by both the number of reactive groups and the molecular weight of DPS. Specifically, obtaining a molecular weight distribution of 8–9.5 kDa favored the production of a coarse flocculant with high characteristic viscosities.

49. 题目: Occurrence of Dissimilatory Nitrate Reduction to Ammonium (DNRA) in Groundwater Table Fluctuation Zones during Dissolved Organic Nitrogen Leaching through Unsaturated Zone
文章编号: N25020905
期刊: Journal of Hazardous Materials
作者: Yujie Hao, Tianyuan Zheng, Lecheng Liu, Peihua Li, Haoran Ma, Zhihong Zheng, Xilai Zheng, Jian Luo
更新时间: 2025-02-09
摘要: Nitrate reduction in the unsaturated zone is critical for preventing groundwater contamination from anthropogenic nitrogen fertilization. Dissimilatory nitrate reduction to ammonium (DNRA), found in anoxic environments, offers an alternative pathway to denitrification by reducing nitrate while conserving nitrogen. However, the occurrence of DNRA in the unsaturated zone remain poorly understood. To address this gap, we conducted numerical simulations to investigate reactive transport of dissolved organic nitrogen (DON) through the unsaturated zone under fluctuating groundwater table conditions, with a focus on the competition between denitrification and DNRA. Our results indicate that DNRA typically gets stronger within the capillary fringe, with its intensity varying with groundwater table fluctuations. DNRA competes with denitrification, contributing up to 46.33% of nitrate reduction, especially when the groundwater table drops. The strength of DNRA requires comprehensive consideration of the adsorption characteristics, permeability and porosity of the lithology, and in our studies, silty clay loam—with relatively weaker adsorptive capacity/lower permeability—exhibits the highest DNRA reaction rates and the largest reaction areas, while DNRA in sandy loam may occur during periods when both DON and NO₃⁻-N reserves are relatively low. This study firstly revealed the distribution of DNRA in the groundwater table fluctuation zone, exploring its kinetics, controlling factors, and contributions, providing a scientific foundation for assessing the self-purification processes in groundwater contamination.

50. 题目: Comparative Study on the Impact of Physicochemical Characteristics of the Activated Carbons Derived from Biochar/Hydrochar on the Adsorption Performances
文章编号: N25020904
期刊: Environmental Research
作者: Ali Akbari, Seyed Jamaleddin Peighambardoust, Hossein Kazemian
更新时间: 2025-02-09
摘要: This research presents a comparative study on the characteristics of the activated carbon (AC) produced from biomass-derived hydrochar (HC) and biochar (BC) and how their physicochemical features affect their performance in organic pollutant remediation. Using a suite of characterization techniques, including BET, SEM, XRD, Raman Spectroscopy, elemental composition, and FTIR, it was determined that HC-derived AC (HAC) exhibited higher oxidation, greater porosity, and more pronounced amorphous structures compared to BC-derived AC (BAC). The HC, BC, HAC, and BAC were also assessed as their oxygenated functional groups (OFGs) and aromatic compounds using a semi-quantitative analysis technique. Notably, HC and HAC displayed higher reactivity, while BC and BAC showed greater aromaticity. Adsorption tests for methylene blue (MB) and ciprofloxacin (CIP) revealed that under optimal conditions (contact time: 170 min, MB and CIP concentrations: 400 mg/L, and temperature: 25°C), HAC achieved superior adsorption capacities (1261.519 mg/g for MB at pH: 8.5 and 1132.86 mg/g for CIP at pH: 5) compared to BAC (1094.704 mg/g for MB at pH: 10 and 838.492 mg/g for CIP at pH: 5). The adsorption processes for MB and CIP were found endothermic and spontaneous, mainly driven by electrostatic attraction, H-bonding, hydrophobic, n-π, and π-π interactions. Furthermore, the reusability study demonstrated high pollutant removal efficiency for HAC and BAC even after 5 adsorption-desorption cycles. This research underscores the superiority of HC as feedstock for producing AC over BC, and it emphasizes the potential of HAC and BAC as cost-effective and reusable adsorbents for enhancing wastewater treatment efficacy.

51. 题目: Moisture and soil depth govern relationships between soil organic carbon and oxalate-extractable metals at the global scale
文章编号: N25020903
期刊: Biogeochemistry
作者: Sophie F von Fromm, Hermann F Jungkunst, Bright Amenkhienan, Steven J Hall, Katerina Georgiou, Caitlin Hicks Pries, Fernando Montaño-López, Carlos Alberto Quesada, Craig Rasmussen, Marion Schrumpf, Balwant Singh, Aaron Thompson, Rota Wagai, Sabine Fiedler
更新时间: 2025-02-09
摘要:

An important control on long-term soil organic carbon (SOC) storage is the adsorption of SOC by short-range-ordered (SRO) minerals. SRO are commonly quantified by measuring oxalate-extractable metals (M_ox = Al_ox + ½ Fe_ox), which many studies have shown to be positively correlated with SOC. It remains uncertain if this organo-mineral relationship is robust at the global scale, or if capturing regional differences is needed to maximize model accuracy. We used a global synthesis of Al_ox and Fe_ox data to test their role in controlling SOC abundance across regions. We compiled 37,344 individual soil horizon measurements, with soil depth ranging between 0 and 200 cm, from 11,122 profiles. We used the Holdridge Life Zones, which are characterized by biotemperature, precipitation, and potential evapotranspiration, to group the soil profiles by their climatic conditions that also correlate with other important soil-forming factors. Based on linear mixed-effects models, we found a positive relationship between M_ox and SOC across regions and depths, accounting for 49% of the SOC variation. This relationship is strongest in wetter regions and at depths between 20 and 100 cm. Across all environmental conditions, Al_ox is a stronger predictor of SOC than Fe_ox. Our analysis suggests oxalate-extractable metals are good proxies for mineral-induced SOC protection at the global scale. However, our findings also indicate that the importance of organo-mineral interactions at the global scale varies with climatic conditions and depth. The underlying mechanisms need to be considered when incorporating these relationships as proxies for mineral sorption capacity into soil C models.

52. 题目: Eco-friendly foams from eucalyptus-bleached cellulose biochars for organic contaminant adsorption in oilfield water
文章编号: N25020902
期刊: Journal of Environmental Chemical Engineering
作者: Lauren M M Machado, Sabrina F Lütke, Daniele Perondi, Christian Manera, Marcelo Godinho, Gabriela C Collazzo, Luis F O Silva, Tito J Crissien, Naushad Ahmad, Sonaimuthu Mohandoss, Guilherme L Dotto
更新时间: 2025-02-09
摘要: Growing concern about the environmental impact of synthetic adsorbents has driven the search for sustainable and effective alternatives. This study breaks new ground by developing eco-friendly foams from eucalyptus-bleached pulp biochars to remove persistent organic pollutants such as naphthenic acid (cyclohexane carboxylic acid) in oilfield-produced water. Eucalyptus-bleached pulp biochars obtained at different temperatures (700, 800, and 900°C) were used as reinforcing material to prepare the foams. Extensive characterization of the foams allowed a detailed understanding of their structure and functionality. The biochars obtained at different temperatures and their integration with reinforcing agents gave the foams a porous structure that varied according to the heat treatment, reflecting on adsorption. The foam porosity was near 80 %, and the naphthenic acid removal reached around 90 %. Adsorption equilibrium studies at pH 4 and 8 revealed that the foam produced with the 900°C-biochar showed the highest efficiency at pH 8, while the foam produced with the 700°C-biochar showed superior results at pH 4. The equilibrium data were well represented by the Langmuir model (qm = 32.44 mg g−1 at pH 4 and qm = 20.33 mg g−1 at pH 8). These results highlight the versatility of the foams for removing pollutants under different conditions. Overall, the produced foams offered an affordable and biodegradable approach to treating petroleum waters, displaying good adsorption efficiency for naphthenic acid. Future studies aim to investigate its efficiency in removing naphthenic acids from real oilfield-produced water.

53. 题目: Green Pathway for Upscaling CO2 and H2O Conversion via Synergizing Nonthermal Plasma with Biochar
文章编号: N25020901
期刊: ACS Sustainable Chemistry & Engineering
作者: Linghan Xia, Yimeng Li, Jianyu Wang, Chuhao Huang, Yonghong Cheng, Guodong Meng
更新时间: 2025-02-09
摘要: The conversion of CO₂ and H₂O into syngas by plasma is a desirable route for utilization of waste resources, energy conversion, and storage. However, it remains a great challenge to acquire satisfying conversion performance for an environmentally friendly and upscaling application. In this work, we propose a green strategy of synergizing nonthermal plasma with biochar for efficient conversion of high-flow CO₂–H₂O and reveal the reaction kinetics. Specifically, this work makes a breakthrough in that we achieve an energy efficiency of 23.6% at high flow rate (2000 mL/min) and H₂O content (50%), significantly outperforming other plasma reactors for CO₂–H₂O conversion. We find that the biochar surface reaction driven by plasma is the key for enhancing CO₂–H₂O conversion, where biochar reacts with OH and O radicals and suppresses recombination reactions of products, thus mitigating the quenching effect of H₂O. This work innovatively scales up CO₂–H₂O conversion, paving an avenue for its industrial application.

54. 题目: Changes in Soil Properties, Organic Carbon, and Nutrient Stocks After Land‐Use Change From Forests to Grasslands in Kumaun Himalaya, India
文章编号: N25020818
期刊: Land Degradation & Development
作者: Archana Fartyal, Surendra Singh Bargali, Kiran Bargali, Bhawna Negi
更新时间: 2025-02-08
摘要: Land‐use changes are anticipated to be a substantial contributor to global change climate, substantially causing significant modifications in soil characteristics. This study addressed the impact of land‐use change from native forests to grasslands on the soil physico‐chemical properties in entirely replicated grasslands of three different forest zones (Oak, Pine and Cypress) in temperate region of Kumaun Himalaya. A total of 162 soil samples (6 sites × 3 plots × 3 seasons × 3 depths = 162 samples) were randomly collected from each site in triplicates from depths. The soil texture, bulk density (bD), porosity, water holding capacity, soil moisture content, pH, organic carbon (SOC), total nitrogen (TN), available phosphorus (P) and available potassium (K) were determined at different depths in forest and grassland sites. Results showed that soil bD, pH, SOC, TN, P and K significantly (p < 0.05) decreased with increasing depth. Moreover, conversion of forests into grassland reduced nutrient concentrations, physical qualities (bD and porosity), and pH levels. The decreasing trend of nutrient along the soil depth explains that the zone of nutrient accumulation is not well established in these grasslands because of the substantial leaching effect. Our findings indicate that conversion of natural forests into grasslands resulted in significant losses of SOC and TN stocks which can be attributed to the disturbance of natural forests. Therefore, while making land‐use change plans, the impact of these alterations on soil nutrients must be considered. These findings emphasize the value of establishing natural vegetation (forests) in these areas to retain nutrients and safeguard soil against runoff and erosion. However, anticipating the physico‐chemical impacts of land‐use alteration necessitates a better comprehension of its relations with other drivers of global change, such as changing climate and nitrogen deposition.

55. 题目: Intertidal zonation of mangrove organic carbon fractions driven by vegetation biomass and soil nutrient levels
文章编号: N25020817
期刊: Catena
作者: Xiaolei Yin, Weiqi Wang, Yuanchun Zou, Zhaoliang Song, Jordi Sardans, Martin Wiesmeier, Georg Guggenberger, Qiang Li, Ji Chen, Josep Peñuelas
更新时间: 2025-02-08
摘要: High net primary production and low soil organic carbon (SOC) decomposition rates ensure that mangroves are important carbon sink likely to be disturbed by rising sea level. The differences in environmental factors along land-sea gradients in mangrove forests influence SOC characteristics.Six typical intertidal zones of mangrove distribution in the subtropical and tropical regions of China were selected for this study. Each intertidal zone was divided into three sections, ranging from land to sea: the landward zone (LW), the middle zone (MZ), and the seaward zone (SW). This classification aimed to investigate the distribution of key driving factors influencing mangrove wetland SOC and its various fractions SOC and its different fractions.The average SOC content ranged between 15.85 and 37.08 g kg−1, and was 31 % and 57 % lower in MZ and SW than LW, respectively.Compared with LW, easily oxidizable-carbon (EOC) content in MZ and SW was 16 % and 58 % lower, and dissolved organic-carbon (DOC) content was 46 % and 67 % lower, respectively.Location affected the characteristics of the distribution of SOC fractions (p < 0.05).Vegetation biomass and total N and P contents were key driving factors affecting SOC content.Mangrove forest age was another important factor affecting SOC. LW environment had the largest total N and P content, leading to larger SOC, EOC and microbial biomass carbon content compared to MZ and SW. We highlight the environmental gradient divergence in the SOC in the intertidal zone found when systematically assessing the SOC pool function of the coastal zone, which warrantsresearch into the SOC cycle in coastal wetlands. Rising sea levels may cover more current tidal mangrove areas and, if there is no space to move inland, current mangrove formations in more tidal areas could disappear. As a result, the C-stored in these mangrove communities could be eroded, sparced and lost.

56. 题目: Effects of Erosion Gully Drainage on Soil Organic Carbon Spatial Differentiation Pattern in Alpine Peatlands
文章编号: N25020816
期刊: Wetlands
作者: Xinyu Ma, Xiawei Zhao, Chengzhang Zhao, Lu Zhang, Haolin Li, Yan Wang
更新时间: 2025-02-08
摘要:

Material input and output are key factors determining the formation and accumulation of soil organic carbon (SOC) in alpine peatlands. The impact of erosion gullies drainage caused by thaw slump on SOC remains unclear. Investigating the SOC spatial differentiation pattern from perspectives of vegetation and hydrothermal conditions can help understand carbon sequestration mechanisms under climate change. This study conducted experiments in drainage alpine peatlands on Zoige Plateau. From undisturbed peatland to the edge of erosion gully, based on water level changes. Four drainage gradient sample plots were designated as follows: undrained (I), lightly drained (II), moderately drained (III), and heavily drained (IV), the effects of community characteristics and soil factors on SOC content at different drainage gradients were studied. Results showed that: Horizontally, the dominant species succession from Carex muliensis (I) to Blysmus sinocompressus (II, III) and Kobresia tibetica (IV), the SOC, soil water content (SWC), C/N, community total biomass (TB), litter count (LC), and root/shoot (R/S) decreased, the soil bulk density (BD), pH, and temperature (ST) increased. Vertically, the SOC in Sample plot I decreased, in Sample plot II, III, and IV initially decreased and then increased. SOC was highly significantly positively correlated with TB, LC, and R/S (p ≤ 0.01). Path analysis indicated that the order of soil factors affecting SOC was SWC > C/N > ST > BD. This study found that drainage influenced hydrological environment of peatlands, community succession altered quantity and quality of material input. These factors disrupted peat accumulation and decomposition balance, changing SOC horizontal and vertical patterns, causing alpine peatlands degradation.

57. 题目: Molecular composition of dissolved organic matter from young organic‐rich hydrothermal deep‐sea sediments
文章编号: N25020815
期刊: Limnology and Oceanography
作者: Jonas Brünjes, Florence Schubotz, Andreas Teske, Michael Seidel
更新时间: 2025-02-08
摘要: Hydrothermal transformations of dissolved organic matter (DOM) are governed by temperature and sedimentary organic carbon content, resulting in the release of hydrothermal DOM containing bioavailable compounds fueling benthic microbes. However, the temperature‐dependent molecular changes in porewater DOM from organic‐rich hydrothermal sediments, and the extent to which these changes contribute to the marine recalcitrant DOM, remain largely unexplored. Here we investigated the DOM composition of hydrothermal porewater and bottom water samples from the Guaymas Basin, Gulf of California, where basaltic sill intrusions generate hydrothermal petroleum in organic‐rich sediments. Samples containing hydrothermal petroleum with in situ temperatures from 4°C to > 106°C were analyzed using Fourier‐transform ion cyclotron resonance mass spectrometry and parallel factor analysis of excitation‐emission matrices from fluorescent DOM (FDOM). We found that the porewater DOM composition was strongly influenced by temperature and petroleum dissolution, evidenced by the enrichment of hydrothermal DOM with highly unsaturated, oxygen‐depleted aromatic, sulfur‐containing molecular formulae and petroleum‐associated FDOM compared to a cold reference site. In bottom waters, hydrothermal DOM accounted for ~ 26% of the DOM molecular formulae, with 82% exhibiting hydrogen‐to‐carbon ratios < 1.5, indicating their recalcitrance. The remaining ~ 18% of the hydrothermal molecular formulae were aliphatic and saturated, representing the release of bioavailable DOM to the ocean. Our results show that hydrothermal sediments are a source of both bioavailable and recalcitrant DOM, releasing water‐soluble petroleum‐derived compounds to the deep ocean. Our study highlights the need for more quantitative research on the contribution of hydrothermal sediments to deep‐sea DOM cycling.

58. 题目: Enhancing anaerobic digestion for treating landfill leachate based on S, N-modified biochar: Synergistic enhancement of microbes-to-pollutants and inter-microbes extracellular electron transfer
文章编号: N25020814
期刊: Journal of Cleaner Production
作者: Xinyuan Wang, Xinyang Liu, Duoying Zhang, Longyi Lv, Jinsong Liang, Li Sun, Xiaoyang Liu, Wenfang Gao, Guangming Zhang, Zhijun Ren, Mengqi Zheng
更新时间: 2025-02-08
摘要: Refractory organic pollutants of high concentration in landfill leachate can lead to the inhibition of the traditional anaerobic biological treatment process and even cause the collapse of anaerobic reactor. Enhancing extracellular electron transfer (EET) rate of microorganisms can effectively improve anaerobic biological treatment efficiency for treating refractory organic pollutants. In this study, the biochar was modified with S and N at the same time, and it was found by various characterization techniques that S, N-modified biochar (S-N-BC) has rich redox functional groups along with excellent electrochemical properties. By adding S-N-BC, the chemical oxygen demand removal was increased by 31.6% compared with the control group, and the specific methanogenic activity was increased by about 40% compared with the control group. Microbial extracellular polymer secretion and average sludge particle size stabilization were promoted by S-N-BC. Establishment of a protective barrier for sludge in the S-N-BC group provided prerequisites and transfer pathways for EET process of microorganisms. In addition, the microbial community was optimized by S-N-BC, the enrichment of functional microorganisms was promoted, and direct interspecies electron transfer pathway among synergistic microorganisms was established. Two-way coupled electron transfer modeling has been proposed, i.e., microbes-to-pollutants and inter-microbes EET. This study provides guidelines for anaerobic biological treatment of actual landfill leachate.

59. 题目: Soils signal key mechanisms driving greater protection of organic carbon under aspen compared to spruce forests in a North American montane ecosystem
文章编号: N25020813
期刊: Biogeosciences
作者: Lena Wang, Sharon Billings, Li Li, Daniel Hirmas, Keira Johnson, Devon Kerins, Julio Pachon, Curtis Beutler, Karla Jarecke, Vaishnavi Varikuti, Micah Unruh, Hoori Ajami, Holly Barnard, Alejandro Flores, Kenneth Williams, Pamela Sullivan
更新时间: 2025-02-08
摘要: . Soil organic carbon (SOC) is often retained more effectively in aspen-dominated forests compared to coniferous forests in North America, yet the reasons why are unclear. A potential driver could be differences in SOC protection mechanisms. Over decades to centuries, chemical (e.g., mineral association) and physical (e.g., aggregation) processes can work to preserve SOC stocks, which can vary across cover types. To investigate this hypothesis, we evaluate controls on SOC concentrations in the Coal Creek watershed (CO, USA), a montane ecosystem dominated by quaking aspen and Engelmann spruce and underlain by granite and sandstone. We examined a combination of biological, chemical, physical, and environmental conditions to evaluate potential abiotic and biotic mechanisms of SOC preservation at multiple depths. As expected, we observed greater SOC under aspen compared to spruce. Growing season soil moisture, temperature, and CO₂ and O₂ varied with slope position and aspect, and thus forest cover type. Dissolved organic carbon (DOC) was lower under aspen compared to spruce. Exo-enzyme data indicate that aspen soil microbes exhibited greater effort to seek organically-bound resources; consistent with this, soil organic N exhibited higher δ¹⁵N values, hinting at a greater degree of organic matter processing. Finally, aspen roots exhibited greater root abundance, and aspen mineral soils revealed smaller mean aggregate diameters compared to conifer sites. Our data suggest enhanced biotic activities in aspen-dominated forest soils that promote both chemical and physical protection of SOC in aspen- relative to spruce-dominated forests, and associated limitations on DOC export.

60. 题目: Dissolved Organic Matter Within Soil Aggregates in Forest Restoration: Insights From Optical Properties
文章编号: N25020812
期刊: Land Degradation & Development
作者: Gui‐bang Zhang, Qing‐wei Zhang, Wen‐xuan Kuan, Jian Wang, Jun'e Liu, Hao Wang, Ming Li
更新时间: 2025-02-08
摘要: Forest restoration with Robinia pseudoacacia L. has many benefits, and dynamics of dissolved organic matter (DOM) might provide insight into soil restoration. Nevertheless, studies regarding the changes in the DOM within soil aggregates during artificial forest restoration are relatively limited in semiarid regions. Soil aggregates were collected from the topsoil, middle soil, and subsoil layers (i.e., 0–20, 30–50, and 80–100 cm) at six forests (i.e., R. pseudoacacia L.) lands with various restoration ages in a typical semiarid region. The variations of DOM properties in silt + clay size classes, microaggregates and macroaggregates (i.e., < 0.053 mm, 0.053–0.25 mm, and > 0.25 mm) were explored by UV–visible and three‐dimensional excited emission matrix spectral. Overall, dissolved organic carbon (DOC) content (41.24–119.82 mg kg−1) of soil aggregates generally increased with restoration age. The DOC content in topsoil aggregates was 3.11–7.13 times larger than those from the other two soil layers. The molecular weight, aromaticity degree, and humification degree had the same trends as that of DOC content with soil depth. The DOC content and aromaticity degree of DOM in macroaggregates were 1.26–4.27 times and 1.01–1.18 times higher than those in microaggregates and silt + clay size classes at most soil layers, respectively. These variations in DOM within soil aggregates were primarily attributed to the changes in soil texture and the densities of plant roots and litter during the forest restoration. The study reveals the positive impact of forest restoration on the increase of DOC content, providing scientific evidence for soil management.