论文检索

总访问量：2137598次

总访客量：105678人

所有论文

181. 题目: Electroactive bacteria-established long-distance electron transfer to oxygen facilitates bio-transformation of dissolved organic matter for sediment remediation
文章编号: N24112307
期刊: Water Research
作者: Yinxiu Liang, Meijun Dong, Shan Yang, Lizhou Lin, Haobin Huang, Daobo Li, Min Ji, Meiying Xu
更新时间: 2024-11-23
摘要: Electroactive bacteria (EAB) in sediment commonly establish long-distance electron transfer (LDET) to access O₂, facilitating the degradation of organic contaminants, which we hypothesize is mediated by the bio-transformation of dissolved organic matter (DOM). This study confirmed that EAB-established LDET to O₂ via a microbial electrochemical snorkel raised the electric potential of sediment by increasing HCl-extracted Fe(III) and NO— 3concentrations while reducing DOM concentrations, which further modified microbial diversity and composition, notably reduced the relative abundance of fermentative bacteria. As a result, DOM showed the highest SUVA₂₅₄ value (3.88) and SUVA₂₈₀ value (1.61), preliminarily suggesting their enhanced aromaticity, humification and average molecular weight. Additionally, these DOM exhibited the highest electron transfer capacity (174.14±3.62 μmol e⁻ /g C) and redox current. Based on these findings, we propose four possible avenues through which EAB-established LDET to O₂ facilitates sediment remediation, mainly including DOM involved affinity, direct and indirect electron transfer, and induced photochemical reaction in degradation or humification process of organic contaminants. Although these proposed avenues require further verification, this work sheds light on deciphering the mechanisms underlying the augmented degradation of organic contaminants facilitated by EAB-established LDET to O₂, offering fresh insights into sediment remediation.

182. 题目: Enhancement of hydrogen production from thermal and catalytic cracking of HDPE through Implementation of activated biochar
文章编号: N24112306
期刊: Chemical Engineering Journal
作者: Kyungil Cho, YongWoon Lee
更新时间: 2024-11-23
摘要: This study investigated hydrogen production characteristics from thermal and catalytic cracking of high-density polyethylene (HDPE) and role of activated biochar derived from biomass (palm kernel shell, PKS). The objective was to enhance hydrogen yield in response to growing demands for hydrogen and the management of waste plastic. Three experimental setups—pyrolysis, thermal cracking, and char cracking—were employed in a two-stage pyrolysis system to examine the impact of reaction temperature and activated biochar on 1) the decomposition of HDPE into tar, which is a complex hydrocarbon mixture, and 2) the production of hydrogen from the vaporized tar. The findings indicated that the reaction temperature in the first reactor influenced tar vapor formation, whereas the temperature in the second reactor was more closely associated with the production of hydrogen and lighter hydrocarbons such as methane. Under identical temperature conditions, the use of activated biochar increased the hydrogen production by more than six times and adsorbed the solid carbon, resulting in no visible carbon particles. Although the reaction temperatures in this study were higher than those in previous studies involving other catalysts, leading to increased energy costs, the abundant biomass sources for carbon activation and the simplicity of the manufacturing process could position activated biochar as a viable catalyst for the thermochemical recycling of plastic into energy source.

183. 题目: Humic acid activated persulfate combined with electrokinetic delivery for remediation of 2, 4-dichlorophenol contaminated soil
文章编号: N24112305
期刊: Science of the Total Environment
作者: Yunfeng Xu, Yufang Jiang, Xiaoxun Huang, Qinqin Lu, Guoqing Shen, Xueping Chen
更新时间: 2024-11-23
摘要: 2,4-dichlorophenol (2,4-DCP) is a high-toxicity phenol compound, which is difficult to remove, poses a threat to human health, and seriously damages the soil ecosystems. In this study, an emerging technology, Electrokinetic (EK) remediation, was used to enhance the mobility of persulfate for remediation of soils contaminated with 2,4-dichloropropanol. In order to improve the overall removal efficiency of 2,4-DCP, Na2S2O8 activated by humic acid (HA) on the remediate effect was investigated. The results showed that the dosage of commercial HA did not affect the physical and chemical properties of the soil, and the optimal dosage was 1.5 g/600 g (HA/soil), in which case the removal efficiency of 2,4-DCP was 73.7 %. When the dosage of compost-derived HA was 1.5 g/600 g (HA/soil), the removal efficiency of 2,4-DCP was 68.66 %. From an economic point of view, compost-derived HA could be used as a good substitute for commercial HA.

184. 题目: Contrasting environmental impacts of nano-biochar and conventional biochar on various organisms
文章编号: N24112304
期刊: Science of the Total Environment
作者: Monika Raczkiewicz, Aleksandra Bogusz, Bo Pan, Baoshan Xing, Patryk Oleszczuk
更新时间: 2024-11-23
摘要: The environmental hazards of nanobiochar (n-BC) require attention due to limited knowledge. This study is the first to explore the effects of biochar size reduction across various organisms, including bacteria (Allivibrio fischeri), plants (Lemna minor, Lepidium sativum), and invertebrates (Daphnia magna, Folsomia candida). Bulk biochar (b-BC) and n-BC were applied in both liquid and solid-phase tests to assess their ecotoxicity. The resulting leachates were tested at concentrations of 2, 10, and 100 mg/L on organisms such as Daphnia magna and Lemna minor. In the solid-phase tests, b-BC and n-BC were added to the OECD soil at concentrations of 1 % and 5 % to evaluate toxicity in Folsomia candida and at concentrations of 1 % to evaluate toxicity in Lepidium sativum. We found n-BC to be significantly more toxic (by 18 % to 2886 %) to A. fischeri than b-BC, with toxicity increasing over time. Low doses (1 %) of both b-BC and n-BC did not cause mortality or inhibit reproduction in F. candida, though b-BC enhanced reproduction (by 30 % to 56 %) compared to n-BC. At a 5 % dose, both b-BC and n-BC inhibited reproduction F. candida, with n-BC being 0.5 to 1.8 times more toxic. Neither b-BC nor n-BC immobilized D. magna, but both inhibited reproduction (by 28 % to 35 %). The nanoscale dimensions of n-BC facilitated bioaccumulation in D. magna, leading to adhesion on the organism's body. The n-BC had a greater impact on plants, both b-BC and n-BC were non-toxic to L. minor, but all n-BC inhibited root growth in L. sativum. These findings highlight the importance of considering biochar size, feedstock, and pyrolysis conditions when evaluating environmental risks, ensuring safe use in sustainable agriculture.

185. 题目: Soil phosphorus compared to nitrogen limitation increases the uncertainty of subsoil organic carbon sequestration in Pinus massoniana mixed forests
文章编号: N24112303
期刊: Journal of Environmental Management
作者: Fenghua Tang, Yunchao Zhou, Piaoyun Deng, Jirong Feng, Yuexiong Mao, Yaoxiong Wang, Qianbin Cao, Zhengui Han, Lulu Meng, Yunxing Bai
更新时间: 2024-11-23
摘要: Limited nitrogen (N) and phosphorus (P) availability will constrain terrestrial carbon sinks in the 21st century. Mixed forests improve the plant community composition and productivity of pure coniferous forests. Nevertheless, it is uncertain whether and to what extent changes in soil N and P dynamics caused by mixed forests can affect forest soil organic carbon (SOC) stocks. The research purpose is to demonstrate and evaluate the effects of soil N and P on SOC stocks in Pinus massoniana mixed forests. Our meta-analysis, which included 616 paired observations, revealed that the coupling of soil N, P, and plant species richness (PSR) contributed 22.6%, 28.8%, and 28.4%, respectively, to SOC stock accumulation in the topsoil (0–20 cm), subsoil (20–100 cm), and whole profile (0–100 cm). The interactions between soil total N and P concentrations (TN:TP ratios) dominated the increase in SOC stocks in the mixed forest topsoil and whole profile, explaining 35.6% and 20.3% of the variation, respectively. Conversely, independent TN and TP concentrations were the primary contributors (explained by 17.5% and 12.3%, respectively) to subsoil SOC stocks increase. The TN and TP concentrations limit SOC stock accumulation in mixed forests for the next 60 years (2025–2085), with the TP concentration and TN:TP ratio having a greater effect in subsoil. Fortunately, the TN and TP limitations on SOC stock increase in mixed forests can be mitigated and balanced by altering soil TN:TP ratio by increasing or decreasing the PSR (PSR thresholds for topsoil, subsoil, and whole profile were 15, 8, and 8, respectively). Overall, plant mixing fails to enhance plant availability of pure forest soil N and P. Accelerated N cycling and increased P reabsorption efficiency are optimal strategies for balancing N and P supply in mixed forests, promoting biomass accumulation, and ensuring SOC stocks increase.

186. 题目: Addition of Fe‐humic acids to overcome analytical issues in measurements of isotopically exchangeable P in soil
文章编号: N24112302
期刊: European Journal of Soil Science
作者: Fien Degryse, William Tucker, Michael J McLaughlin
更新时间: 2024-11-23
摘要: Isotopic dilution has been widely used to measure isotopically exchangeable phosphorus (P) in soil (E value), as a measure of potentially plant‐available P. However, in soils with low E values and/or strong P sorption, measurement of E values can be challenging due to very low solution concentrations and the interference of colloidal non‐exchangeable species, thus confounding the measurements in the soils of most interest. The addition of a complexing compound could increase solution concentrations and reduce these analytical issues, as has been found in the case of metals. Therefore, we investigated the addition of Fe‐humic acid (Fe‐HA) as a P‐complexing compound to the soil suspension prior to isotopic exchange. This results in the formation of P‐Fe‐HA complexes, thus increasing P solution concentrations by solubilizing P from the labile pool and reducing errors caused by suspended colloids. We used this method to measure E values in five soils with low P status, without or with the addition of carrier P. The addition of Fe‐HA (at 50 or 200 mg Fe‐HA/L to the equilibration solution) substantially decreased the measured E value without carrier P addition in four of the five soils, while there was no or little effect when carrier P was added. The higher Fe‐HA rate increased solution concentrations of stable and radioactive P more than the lower rate, but there was no significant difference in measured E values between the two Fe‐HA rates. The method was also applied to 15 subsoils with low P status. Overall, our results indicated that the addition of Fe‐HA provides an easy and robust way to avoid analytical issues in the determination of E values in soils with low concentrations of P in solution.

187. 题目: Effects of biochar on plant and microbial communities in landfill soil
文章编号: N24112301
期刊: Applied Soil Ecology
作者: Jiaxin Liao, Guangcun Hao, Haowen Guo, Hongqi CHEN
更新时间: 2024-11-23
摘要: Ecological restoration in landfills encounters a significant challenge attributed to unfavourable soil conditions. A three-month field study was conducted to evaluate biochar effects on plant succession and bacterial community in a landfill cover. The topsoil of the cover was amended with 0, 5, and 10 % (v/v) peanut shell biochar. According to the measured results, adding biochar improves the soil pH, nutrition content, and organic matter up to 2 times, promoting plant growth. Bacterial richness and diversity were enhanced, and the heterogeneity of microbial communities was increased in biochar-amended cases. However, the plant diversity was reduced, and the domain plant species changed in biochar-amended soil. Biochar application strengthens the interaction between fungal communities and Cyperus rotundus L. by enhancing soil chemical properties. This study demonstrates biochar effects on soil-plant-microbe interactions for guiding the ecological restoration of landfill covers.

188. 题目: Engineered biochar for in-situ and ex-situ remediation of contaminants from soil and water
文章编号: N24112220
期刊: Science of the Total Environment
作者: Masud Hassan, Bing Wang, Pan Wu, Shengsen Wang
更新时间: 2024-11-22
摘要: Tailoring physical and chemical properties of biochar enhances its selectivity, treatability, and efficiency in contaminant remediation. Thus, engineered biochar has emerged as a promising remedy for both in-situ and ex-situ remediation of polluted soil and water. Several factors influence the effectiveness of engineered biochar, including feedstock sources, pyrolysis conditions, surface functionalization, mode of application, and site characteristics. The advantages and disadvantages of different modification approaches to engineered biochar and their specific treatability for in-situ and ex-situ remediation are obscure and must be adequately addressed. This review critically evaluates the application of engineered biochar for on/off-spot contamination management, taking into account the long-term stability and biocompatibility prospects. The properties of engineered biochar resulting from modification with clay minerals, nanoparticles, polymers, surfactants, and oxidants/reductants were critically reviewed. Recent progress and advances in remediation mechanisms and modes of application were elaborated for the effective removal of organic and inorganic contaminants, including heavy metals, pesticides, dyes, polycyclic aromatic hydrocarbons, per- and poly-fluoroalkyl substances, and agrochemicals. Several crucial parameters influence in-situ remediation, including the distribution of contaminants, background electrolytes, hydraulic conductivity, as well as dispersion and stability of adsorbents. Ex-situ remediation of pollutants relies heavily on adsorption or degradation kinetics, background electrolytes, adsorbent dose, and pollutant concentrations. In addition, factors restricting the application of engineered biochar were highlighted for long-term sustainable contaminant management and maintaining low environmental impact. Finally, the challenges and future perspectives of utilizing engineered biochar for field-scale demonstration of contaminated sites are proposed.

189. 题目: Estuarine wetland tidal organic carbon activates microbial carbon pump and increases long-term soil carbon stability
文章编号: N24112219
期刊: Catena
作者: Mengdi Xie, Haoyu Dong, Xiaolu Tang, Liwei Qian, Wenxuan Mei, Jianfang Yan, Xiaohua Fu, Yu Hu, Lei Wang
更新时间: 2024-11-22
摘要: Capture of tidal organic carbon (TOC) in estuarine systems can increase soil respiration (SR) and OC breakdown, but it is also revealed tht TOC input intensity may influence the accumulation of microbial necromass, which affects soil carbon sink of estuarine wetland. To clarify how TOC input affects the microbial carbon pump and SOC stability, we conducted a 6-year field study in low and high flats of the Yangtze River estuary and examined C cycling processes. In low tide flats, where TOC input decreased from upstream to downstream, SR decreased with the increases of SOC, whereas the microbial necromass contribution to SOC decreased from 52.16% to 41.75%, which was higher than the contribution of plant-derived refractory C. Additionally, on a mudflat, which had the highest TOC capture but lacked plant C input, microbial necromass accounted for the largest percentage of SOC (61.45%). These indicated that TOC input could increase the contribution of microbial necromass C toward SOC, in comparation with plant lignin. And the promotion of TOC input to OC stability of wetland soil would become significant with the accumulation of TOC in soil after a long period. The analysis of bacterial and fungal community structure verified this speculation that the abundance of C-associated heterotrophic bacteria and fungi increased in soil with high TOC input. These findings further supplement our previous study about the short-term inhibition effect of TOC input to SOC sequestration.

190. 题目: Redox Oscillation-Driven Production of Reactive Oxygen Species from Black Carbon
文章编号: N24112218
期刊: Environmental Science & Technology
作者: Xuan Li, Mengxi Tan, Binbin Wu, Jingyi Wang, Junye Ma, Baoliang Chen, Chiheng Chu
更新时间: 2024-11-22
摘要: Wildfire and stubble burning release substantial amounts of black carbon (BC) into natural environments that experience frequent redox oscillations, such as wetlands and farmlands. Here, we report that redox oscillations can effectively drive ROS production from BC. Following sequential microbial reduction and air exposure, 6.5 ± 0.2 μM/g_C hydrogen peroxide (H₂O₂) and 285.3 ± 9.5 nM/g_C hydroxyl radical (•OH) were produced from BC. Moreover, BC derived from various biomass sources, temperatures, and particle sizes exhibits 111.5-fold variations in ROS production. Electrochemical analyses revealed that both the electron transfer capacity and the ROS production selectivity are critical determinants of ROS generation under redox oscillations. The variation in electron transfer capacity (0.3–5.7 mmol e^–/g_C) is primarily governed by the abundance of electron-storing moieties such as quinones, while the ROS generation selectivity (26.2–72.0%) is influenced by the presence of competitive sites for oxygen reduction reactions, such as carbon defects. These findings provide insights into ROS production from BC under fluctuating redox conditions, with potential implications for elemental cycles and pollutant dynamics in regions prone to wildfire and stubble burning events and substantial BC deposition (e.g., wetlands and rice paddies).

191. 题目: Enrichment and catalysis effect of 2D/2D g-C3N4/Ti3C2 for promoting organic matter degradation and heavy metal reduction in plasma systems: Unveiling the promotion and redox mechanism
文章编号: N24112217
期刊: Journal of Hazardous Materials
作者: Yawen Wang, Wenxuan Jiang, Nan Jiang, Jie Li, He Guo
更新时间: 2024-11-22
摘要: This work proposes a novel plasma-assisted 2D/2D g-C3N4/Ti3C2 system for treatment of organics-heavy metals composite wastewater. Unlike traditional materials in plasma system, 2D/2D g-C3N4/Ti3C2 not only improved the mass transfer efficiency of plasma by gathering both reactive species and pollutants onto the surface, but also induced photocatalytic reactions. Besides, the higher specific surface area and faster carrier separation rate can enhance the oxidation and reduction activity, and then promoted organic matter degradation and heavy metal reduction. Remarkably, the removal efficiency of sulfamethoxazole (SMX) and Cr(VI) increased by 16.5 % and 73.1 % respectively when introducing 2D/2D g-C3N4/Ti3C2. Roles of·OH,·H,·O2-, 1O2, e-, and h+ in SMX oxidation and Cr(VI) reduction are clarified. The primary aggregated·OH and 1O2 dominate the degradation of SMX. The influencing factors, synergistic mechanism between plasma and catalyst, and redox mechanism were clarified. This work provides a breakthrough idea for treatment of organics-heavy metals composite wastewater.

192. 题目: Variable toxicity of inorganic mercury compounds to Artemia elicited by coexposure with dissolved organic matter
文章编号: N24112216
期刊: Environmental Science and Pollution Research
作者: Christoph Gade, Rebecca von Hellfeld, Lenka Mbadugha, Graeme Paton
更新时间: 2024-11-22
摘要:

The chemical behavior of mercury (Hg) and its interactions with naturally occurring ligands shape its environmental fate and impact. The neurotoxic properties of Hg are widely known and studied both in vitro and in vivo. However, there continues to be limited information on the influence of chelation with large organic ligands on the toxicity to marine macro-organisms. This work examined the effect of Hg complexed with various types of dissolved organic matter (DOM) on the mortality and hatching success of Artemia sp. nauplii under varying marine media conditions. The results confirmed both, an alleviating as well as additive, DOM-specific, effect on mortality. DOM coexposure resulted in a compound specific decreased or increased toxicity in comparison with single exposure in artificial seawater, with LC₅₀ values ranging from 2.11 to 62.89 µM. Hatching success under conditions of Hg exposure was almost two orders of magnitude more sensitive than toxicity in hatched individuals. Elevated DOM concentrations had no statistically significant impact on hatching success with computed EC₅₀ values ranging from 196 to 324 nM.

Graphical abstract

193. 题目: Effects of the conversion of croplands to wetlands on the components and sources of soil organic carbon
文章编号: N24112215
期刊: Catena
作者: Yongkang Zhao, Guodong Zheng, Junyu Dong, Zhiliang Wang, Hepeng Xu, Changchao Li, Yijing Wang, Yan Wang, Xiaoke Liu, Huaizhi Bo, Jian Liu
更新时间: 2024-11-22
摘要: Land use/cover change (LUCC) plays an important role in soil organic carbon (SOC) storage. However, the responses of SOC components to LUCC and the contribution of microbial-derived carbon (typically represented by microbial necromass carbon, MNC) to SOC in wetland-related LUCC remain unclear. In this study, we investigated the responses of SOC components and the contribution of microbial-derived carbon to SOC in three newly formed wetlands that were converted from croplands by coal mining subsidence and have developed for 1, 6, and 15 years, respectively. The findings revealed that the conversion initially led to the decrease of SOC, and then recovered with time, in which occluded particulate organic carbon (oPOC) dominated the response of SOC to the conversion and significantly accumulated in the wetland with 15 years of development. Moreover, our study found that MNC accounted for a minor fraction (5.9 %–13.1 %) of SOC in the newly formed wetlands, which is contrary to the dominant role of MNC in the contribution to SOC in upland soils. Our study provides evidence for understanding the role of microbial-derived carbon in newly formed wetlands and highlights the importance of oPOC when focusing on the effects of LUCC on SOC storage.

194. 题目: Microbial and mineral interactions decouple litter quality from soil organic matter formation
文章编号: N24112214
期刊: Nature Communications
作者: Dafydd M O Elias, Kelly E Mason, Tim Goodall, Ashley Taylor, Pengzhi Zhao, Alba Otero-Fariña, Hongmei Chen, Caroline L Peacock, Nicholas J Ostle, Robert Griffiths, Pippa J Chapman, Joseph Holden, Steve Banwart, Niall P McNamara, Jeanette Whitaker
更新时间: 2024-11-22
摘要:

Current understanding of soil carbon dynamics suggests that plant litter quality and soil mineralogy control the formation of mineral-associated soil organic carbon (SOC). Due to more efficient microbial anabolism, high-quality litter may produce more microbial residues for stabilisation on mineral surfaces. To test these fundamental concepts, we manipulate soil mineralogy using pristine minerals, characterise microbial communities and use stable isotopes to measure decomposition of low- and high-quality litter and mineral stabilisation of litter-C. We find that high-quality litter leads to less (not more) efficient formation of mineral-associated SOC due to soil microbial community shifts which lower carbon use efficiency. Low-quality litter enhances loss of pre-existing SOC resulting in no effect of litter quality on total mineral-associated SOC. However, mineral-associated SOC formation is primarily controlled by soil mineralogy. These findings refute the hypothesis that high-quality plant litters form mineral-associated SOC most efficiently and advance our understanding of how mineralogy and litter-microbial interactions regulate SOC formation.

195. 题目: Acid-modified biochar-based bacterial fertilizer and increase soil available phosphorus
文章编号: N24112213
期刊: Journal of Soils and Sediments
作者: Chenhui Qi, Chuanyu Zhang, Zihe Yang, Nana Liu, Yu Gao, Ruotong Wang, Dongye Huang, Fei Tian, Wei Li, Chao Wei, Zhansheng Wu
更新时间: 2024-11-22
摘要:

Purpose

The various biochars were modified by phosphoric acid to load phosphorus-solubilizing microorganisms to prepare biochar-based fertilizers (BFs) in this study. The purpose is to provide a new way to develop and utilize BFs to improve available phosphorus and reduce fertilizer consumption.

Materials and methods

We conducted a 2-hour pyrolysis of apple wood and cotton straw using a muffle furnace at different temperatures to obtain apple wood biochar and cotton straw biochar, respectively. The prepared biochar was modified using sulfuric acid, hydrochloric acid, and nitric acid. Enterobacter hormaechei. Wu-15 and biochar (10:1) were put into the conical flask. The conical flask was shaken for 1 h to yield BFs, which were subsequently applied in soil at mass ratio of 1:20, 1:10 and 3:20 over a period of 15 days. The experiment was conducted under soil conditions of different pH (5–7) and temperature (20–30 ℃).

Results and discussion

Enhancing hydrophobicity promotes the adhesion of microorganisms to biochar. The enhanced presence of functional groups and the honeycomb structure significantly improved the adsorption performance of biochar, resulting in an adsorption capacity for microorganisms that reached 2.23 × 10⁹/g. The application of acid-modified biochar-based bacterial fertilizers (ABFs) in soil resulted in maximum total phosphorus and soluble phosphorus concentrations reaching 37.21% and 16.65%, respectively, due to the synergistic interaction between biochar and phosphorus-solubilizing bacteria.

Conclusion

Phosphoric acid-modified biochar exhibits an enhanced pore structure and superhydrophobicity properties, facilitating the adhesion between biochar and microorganisms. This modification can augment the effective phosphorus content in soil, thereby contributing to agricultural productivity.

Graphical abstract

196. 题目: Effects of incorporating biochar on soil quality and barley yield in microplastics-contaminated soils
文章编号: N24112212
期刊: Chemosphere
作者: Aya Debab, Sonia Boudjabi, Haroun Chenchouni, Nawal Ababsa, Amna Brahimi
更新时间: 2024-11-22
摘要: Biochar has been recognized for its potential to improve the fertility soils by reducing the reliance on chemical fertilizers, mitigating carbon emissions, and fostering soil microbial growth. This study aimed to evaluate the impact of biochar addition on the physicochemical properties of arid and semi-arid soils containing microplastics, while also assessing its effect on Barley (Hordeum vulgare) yield under drought stress. The experiment was conducted in a glass greenhouse. Plastic pots containing 3 kg of soil were each planted with 6 barley grains. Biochar was applied at three doses (B0 = 0 g biochar/kg soil, B1 = 6 g biochar/kg soil, B2 = 10 g biochar/kg soil), while microplastics were added at three levels (M0 = Control without microplastics, M1 = 0.5 g/kg soil, and M2 = 1 g/kg soil) on the same sowing date. Water stress was induced when the plants reached the four-leaf stage. ANOVAs and Tukey post-hoc tests were employed for multiple mean comparisons of soil and plant parameters. Drought stress and microplastics negatively influenced soil parameters namely soil moisture, organic carbon, and nitrates, while also affecting electrical conductivity and pH. Biochar exhibited minimal effect on soil properties but significantly altered pH, nitrates, and total CaCO3. Plant chlorophyll levels decreased under stress, particularly with microplastic dose M1. However, biochar and microplastics enhanced chlorophyll a content, except for dose B1 of biochar, which leads to a decrease in chlorophyll b (0.91 ± 0.138 μg/g FM). Microplastics, at dose M2, improved chlorophyll b content (1.11 ± 0.090 μg/g FM). Aboveground biomass, leaf area, and yield were generally unaffected by tested stresses. Nonetheless, barley grain yield decreased in biochar and microplastic dose M1 (0.47 ± 0.108 g/plant), while it improved with microplastic dose M2 (0.65 ± 0.168 g/plant). Leaf relative water content increased under water stress and microplastics but not with biochar alone. Interaction between microplastics and biochar enhanced plant water content. Drought stress and microplastics diminished soil parameters, whereas biochar lowered nitrates and pH without significantly affecting soil organic carbon. Plant productivity parameters generally exhibited no significant change under water stress, microplastics, or biochar, except for yield and chlorophyll pigments.

197. 题目: The contributions of dark microbial CO2 fixation to soil organic carbon along a tropical secondary forest chronosequence on Hainan Island, China
文章编号: N24112211
期刊: Catena
作者: Yanfei Sun, Meiqiu Yang, Yi Ding, Danting Deng, Zongrui Lai, Wenxing Long
更新时间: 2024-11-22
摘要: Nonphototrophic CO2 fixation by microorganisms can reduce soil pore CO2 to organic matter in the dark. Tropical forest restoration changes soil microbial community structure and organic carbon (SOC) storage. However, whether the capacity for dark CO2 fixation is altered and contributes to SOC accumulation during tropical forest restoration remains unclear. Here, in the topsoil and deep soil of a tropical forest restoration chronosequence, we investigated chemoautotrophic and heterotrophic microbes and pathways involved in dark CO2 fixation using a metagenome and quantified CO2 fixation rates with a 13C–CO2 labelling experiment. Tropical forest restoration altered the autotrophic CO2 fixation pathway abundance in the Ah horizon, which showed an increasing trend. Heterotrophic carboxylase gene abundance was influenced by soil layer and was more abundant in the B horizon. The main microbes involved in CO2 fixation belong to Acidobacteria, Proteobacteria, and Actinobacteria. 13C–CO2 labelling showed that the CO2 fixation rates across the restoration chronosequence ranged from 0.035 to 0.155 μg C/g soil d−1, and the middle- and late-stage secondary forests exhibited higher rates compared to other stages. The microbial assimilation of CO2 into mineral-associated organic carbon was also observed and the rate exhibited a similar trend to that into SOC, indicating that dark CO2 fixation contributes to stable carbon formation. Tropical forest restoration influenced the CO2 fixation rate indirectly by changing microbial CO2 fixation gene abundance. Specifically, autotrophic pathways (Calvin, reductive citrate, and Wood−Ljungdahl cycles) and heterotrophic carboxylase genes (phosphoenolpyruvate and pyruvate carboxylases) were vital for CO2 fixation in the Ah and B horizons, respectively. Our results suggest that SOC formed by microbial CO2 assimilation contributes to the long-term soil carbon sequestration, especially in secondary forests, which have recovered to middle- and late-stages. The study highlights the importance of dark microbial CO2 fixation in soil carbon sequestration and provides a new understanding of tropical forest soil carbon processes.

198. 题目: Understanding the physicochemical structure of biochar affected by feedstock, pyrolysis conditions, and post-pyrolysis modification methods - A meta-analysis
文章编号: N24112210
期刊: Journal of Environmental Chemical Engineering
作者: Mohammad Ghorbani, Elnaz Amirahmadi, Wim Cornelis, Khaled Zoroufchi Benis
更新时间: 2024-11-22
摘要: The impact of feedstock type, pyrolysis conditions, and post-pyrolysis modifications on the physicochemical properties of biochar has not been systematically evaluated. To this, a comprehensive meta-analysis was conducted to assess the impact of 17 effective variables including three groups of modification techniques (acidic, alkalic, H₂O₂, metal oxides, microbial, organic acids, physical, soil mineral), pyrolysis temperature (<400, 400-550, >550 °C), and feedstocks (herbaceous, hull, manure, nut, straw, wood). Also, 26 properties of the biochar were identified as being impacted; some of the most important among them are pH, cation exchange capacity (CEC), ash content (AC), specific surface area (SSA), carbonization (H/C), and surface functional groups (SFGs). The CEC of biochar modified by acidic, and soil mineral treatment significantly increased by 44.8% and 48.5%. The H/C ratio of biochar decreased in alkalic modification with a negative effect size of 7.2%. Soil minerals, metal oxides, and alkalic modifications resulted in a positive change in AC with a 20.9%, 15.7%, and 13.6% increase. Also, the highest SSA of modified biochar was observed when acidic and H₂O₂ modification methods were applied, with 57.1% and 53.4% effect sizes. Further, high pyrolysis temperature (>550 °C) aided in significantly increasing SSA and SFGs on modified biochar. Overall, the strong association of acidic modifiers, high pyrolysis temperature, and high lignin-based feedstock could contribute to high SSA, SFGs, and absorption efficiency of biochar. This meta-analysis establishes a robust comparative framework, advancing the precision of biochar modification strategies to maximize physicochemical properties for improved environmental remediation.

199. 题目: Effects of increasing rainfall on organic carbon release and transport processes in permafrost on the central Tibetan Plateau
文章编号: N24112209
期刊: Catena
作者: Haotian Wei, Enlong Liu, Chuan He, Bingtang Song, Dan Wang, Jian Kang, Ling Chen, Qiong Li
更新时间: 2024-11-22
摘要: Rainfall can alter the hydrothermal state of permafrost, subsequently affecting organic carbon decomposition and CO2 transport. However, the mechanisms by which rainfall influences organic carbon decomposition and carbon dioxide transport processes in permafrost remain unclear. In this study, a coupled permafrost water-heat-vapor-carbon model, based on the surface energy-water balance theory, is employed to explore the effects of increased precipitation on permafrost moisture, temperature, organic carbon decomposition, and carbon dioxide transport through numerical simulations. The results are as follows: (1) with increased rainfall, surface latent heat flux rises while surface sensible heat flux declines, leading to a reduction in surface heat flux. The annual mean surface heat fluxes for the three precipitation conditions of no change in precipitation (ΔP = 0 mm), 50 mm increase in precipitation (ΔP = 50 mm) and 100 mm increase in precipitation (ΔP = 100 mm) are −0.1 W/m2, −0.2 W/m2 and −0.4 W/m2 respectively; and (2) as rainfall increases, soil moisture content increases significantly, but the impact of rainfall on soil moisture content diminishes with increasing soil depth; and (3) increased rainfall results in a decrease in soil carbon fluxes, soil organic matter decomposition rates, and CO2 concentrations. Compared to the case of constant precipitation, the surface carbon fluxes decreased by 0.04 μmol·m-2s-1 and 0.08 μmol·m-2s-1 under ΔP = 50 mm and ΔP = 100 mm, respectively. Additionally, the decomposition rate of soil organic matter at 10 cm depth decreased by 3.2 E-8 mol·m-2s-1 and 6.3 E-8 mol·m-2s-1, respectively, while the soil carbon concentration decreased by 3 μmol/mol and 5 μmol/mol, respectively.

200. 题目: Humidity controls soil organic carbon accrual in grassland on the Qinghai–Tibet Plateau
文章编号: N24112208
期刊: Soil Biology and Biochemistry
作者: Zhen-Huan Guan, Bin Jia, Zi-qi Niu, Xiao-Ming Mou, Jie Chen, Fen-Can Li, Yi-Ning Wu, Shijie Ning, Kuzyakov Yakov, Xiao Gang Li
更新时间: 2024-11-22
摘要: The huge soil organic C (SOC) storage (around 34 Pg in the top 0.7 m) in Qinghai–Tibet Plateau (QTP) grasslands is commonly explained by slow decomposition of litter under cold climate therein, but this view may not be reliable as humidity also affects microbial activity. We sampled the 20 cm topsoil of grasslands along an altitudinal gradient from 1286 m on the western Loess Plateau (LP) to 4200 m above sea level on the northeastern QTP. The light-fraction SOC (LFOC), composition of non-cellulosic neutral carbohydrates, and amino sugars were used as biomarkers to investigate the intensity of microbial action on SOC as a function of climate along this altitudinal gradient. From the lowest- to the highest-humidity site with rising altitude, the root biomass tripled and the SOC content increased approximately sevenfold (from 13.5 g kg^–1 to 93.3 g kg^–1). The non-cellulosic neutral carbohydrate, microbial biomass C (MBC), and microbial necromass C (MNC) contents increased, but the LFOC content decreased. The contribution of MNC to the SOC and ratios between microbially- and plant-derived sugars in the non-cellulosic carbohydrate pool increased, but the proportion of LFOC in the SOC dropped. Consequently, besides the increased root biomass, the selective preservation of microbial compounds at colder and more humid sites contributed to SOC accruals in grasslands. The higher MBC in cold and humid grasslands perfectly explained the increased selective preservation of microbial derived C at the expense of plant C in higher- relative to lower-altitude areas. Importantly, the above humidity-controlled accumulations of microbial substances and SOC in grasslands were confirmed by results synthesized from published data across the LP and QTP. The higher SOC contents in cold and humid QTP grasslands relative to warm and dry regions were ascribed to the increased accumulation of microbial residues because of the increased humidity in QTP grasslands.