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101. 题目: Mechanisms of N-doped microporous biochar decreased Cd transition in rhizosphere soils and its impact on soil bacterial community composition
文章编号: N24090114
期刊: Science of the Total Environment
作者: Honghong Li, Zhou Li, Jun Long, Jiayi Fu, Chen Chen
更新时间: 2024-09-01
摘要: Soil cadmium (Cd) contamination has garnered considerable attention. This study employed batch sorption experiments and rhizobox experiments to examine the impact of nitrogen-doped microporous biochar (NBB) on the temporal and spatial distribution of Cd in the rhizosphere of rice plants, with the aim of elucidating the underlying mechanisms. The results indicated that the adsorption of Cd(II) onto NBB was predominantly governed by chemical reactions. When applied to soil, the NBB significantly hindered the migration of Cd from the bulk soil to the rhizosphere. Additionally, the application of NBB decreased the redox potential (Eh) in the rhizosphere soil and increased the relative abundance of , , , and , which could facilitate the reduction of soil Cd availability. Furthermore, the NBB2 treatment encouraged the formation of iron plaque on the root surface, thereby limiting the uptake of Cd from the soil into the root system. Moreover, the N-doped microporous biochar treatment resulted in lower Cd levels in the stele of root, an effect that was associated with increased sulfur (S) content in the stele and epidermis, suggesting a potential role for S in Cd sequestration. Ultimately, the application of N-doped microporous biochar resulted in diminished Cd accumulation in the rice tissues.

102. 题目: Contrasting effects of iron oxides on soil organic carbon accumulation in paddy and upland fields under long-term fertilization
文章编号: N24090113
期刊: Journal of Environmental Management
作者: Dong Wu, Lei Wu, Kailou Liu, Jianying Shang, Wenju Zhang
更新时间: 2024-09-01
摘要: Active iron oxides, especially poorly crystalline forms, benefit soil organic carbon (SOC) accumulation via directly bounding and indirectly promoting aggregation. However, it remains unclear on the impacts of active iron oxides on SOC accumulation in paddy and upland soils under long-term fertilization regimes. Here, we attempted to clarify the underlying mechanisms of amorphous (Fe) and organically complexed (Fe) iron oxides mediating SOC accumulation in paddy and upland soils based on two long-term fertilization experiments (both including no fertilization [CK]; chemical nitrogen, phosphorus and potassium [NPK] and NPK plus manure [NPKM] treatments). Results showed that compared to upland soil, Fe-bound organic carbon (Fe-bound OC) content in paddy soil, occupying 21–30% of SOC, was 77% higher on average, due to larger amounts of Fe (+31%) and Fe (+224%). The Fe and Fe were positively related to mean weight diameter (MWD) of soil aggregates across paddy and upland soils. Compared to NPK treatment, NPKM treatment strongly increased Fe (+41%), Fe (+60%) and associated Fe-bound OC (+19%) in paddy soil, and increased Fe (+17%) and Fe (+25%) while decreasing Fe-bound OC (−9%) in upland soil. These combined findings indicated the importance of poorly crystalline iron oxides facilitating Fe-bound OC formation and its contribution to SOC accumulation in paddy soil rather than upland soil. Moreover, long-term manure amendment could enhance SOC accumulation by increasing Fe-bound OC and aggregation stability in paddy soil and enhancing physical protection in upland soil, largely attributed to increased poorly crystalline iron oxides. Overall, these results highlight the potential mechanisms through which active iron oxides regulate SOC accumulation and guide fertilization management in paddy and upland soils.

103. 题目: Soil macroaggregate-occluded mineral-associated organic carbon drives the response of soil organic carbon to land use change
文章编号: N24090112
期刊: Soil and Tillage Research
作者: Zihuan Fu, Wei Hu, Mike Beare, David Baird
更新时间: 2024-09-01
摘要: Understanding land use effects on carbon sequestration in various soil fractions is vital to mitigating climate change and restoring soil functions. The objective of this study was to explore the effects of land use on soil organic carbon (SOC) fractions in different soil types. For this purpose, we studied the effects of long-term (>20 years) land use including dryland pasture (DP), irrigated pasture (IP) and irrigated cropland (IC) on SOC in water-stable aggregates, particle-size fractions, and their coupling relations at the surface soils (0–7.5 cm) in the Canterbury Plains, New Zealand. For each land use, three typical soil types with contrasting drainage levels (i.e. well drained Lismore soil, LIS; imperfectly drained Templeton soil, TEM; and poorly drained Waterton/Temuka soil, WAT) were selected. Macroaggregate-occluded mineral-associated organic carbon (M-MAOC) contributed to the majority of the total SOC difference and drove the response of SOC to land use change. On average, M-MAOC followed an order of IP > DP > IC. The effects of land use change from DP to IP and IC on M-MAOC varied, and these variations were dependent on soil type. The relative gain in M-MAOC with change in land use from DP to IP was the greatest in the well drained LIS soil, while both the relative and absolute loss in M-MAOC following the land use change to IC was the greatest in the poorly drained WAT soil. The interactive effects of managements (e.g. irrigation and cultivation) and soil type (e.g. soil water condition) on aggregate size distribution and macroaggregate-associated C concentration were important in explaining the responses of M-MAOC to land use change. This study advances the mechanistic understanding of total SOC dynamics in response to land use (changes) in different soil types. It also highlights the potential of M-MAOC to serve as a diagnostic fraction to reflect changes in total SOC, which may have application to global warming mitigation.

104. 题目: Joint regulation of the soil organic carbon accumulation by mineral protection and microbial properties following conservation practices
文章编号: N24090111
期刊: Catena
作者: Changdong Han, Lin Chen, Zhongjun Jia, Hongtao Zou, Ling Ma, Biao Feng, Jingwang Li, Guixiang Zhou, Congzhi Zhang, Donghao Ma, Jiabao Zhang
更新时间: 2024-09-01
摘要: Soil aggregates with spatially heterogeneous microenvironments influence microbial communities and mineral protection in agricultural soils and play a pivotal role in soil organic carbon (OC) turnover. However, the mechanisms through which conservation practices affect microbial properties and mineral protection to regulate soil OC accumulation at the aggregate scale has not been determined in the black soil region of Northeast China. Here, we investigated the potential mechanisms of soil OC accumulation in two sets of conservation (Cons) and conventional (Conv) soil samples: (1) Cons (no-tillage with straw mulching) and Conv (rotary tillage with straw removal) in a Phaeozem (Lishu County) and (2) Cons (rotary tillage with straw incorporation) and Conv (rotary tillage with straw removal) in a Chernozem (Da’an County). The soil aggregates were classified into three fractions: macroaggregates (0.25–2 mm), microaggregates (0.053–0.25 mm), and silt and clay (< 0.053 mm). Cons significantly increased soil OC by increasing macroaggregate-associated OC. Cons significantly increased the concentrations of free iron oxides (Fe), iron-bound OC and calcium-bound OC in macro- and microaggregates (except in calcium-bound OC within microaggregates in Lishu) and increased exchangeable calcium (Ca) in Da’an. Additionally, Cons significantly increased the relative abundance of Gemmatimonadota in functionally and topologically important (FTI) taxa within macroaggregates. In Da’an, the relative abundance of Ascomycota in FTI taxa within the macroaggregates and microaggregates was significantly greater in Cons. Cons significantly reduced microbial network complexity (except in microaggregates in Lishu). Structural equation modeling indicated that conservation practices regulated stable OC pools accumulation through mineral protection (mainly Ca and Fe) and network complexity to increase macroaggregate-associated OC. Our findings emphasize the joint role of soil minerals and microbes in increasing soil OC through the modulation of macroaggregate-associated OC accumulation, which has important implications for enhancing soil quality and improving agricultural sustainability.

105. 题目: Influence of biochar amendment on removal of heavy metal from soils using phytoremediation by Catharanthus roseus L. and Chrysopogon zizanioides L.
文章编号: N24090110
期刊: Environmental Science and Pollution Research
作者: Dhritilekha Deka, Deepak Patwa, Archana M Nair, Karangat Ravi
更新时间: 2024-09-01
摘要:

Advances in sustainable toxic heavy metal treatment technologies are crucial to meet our needs for safer land to develop an urban resilient future. The heavy metals bioaccumulate in the food chain due to their persistence in the soil, which poses a serious challenge to its removal and control. Utilisation of hyperaccumulators to reduce the mobility, accumulation and toxic impact of heavy metals is a promising and ecologically safe technique. Amendments such as biochar and chelates have been shown to enhance the phytoremediation efficiency. However, the potential soil improvement is influenced by the properties of the amendment, plant and metal heterogeneities. In this study, an organic sugarcane bagasse biochar amendment for the 60-day pot experiment using Catharanthus roseus L. (NT) and Chrysopogon zizanioides L. (VT) in a heavy metal–contaminated soil was applied. The influence of biochar on the phytoremediation of lead (Pb), zinc (Zn) and cadmium (Cd) from the soil was explored. The plant survival rate enhanced to 100% with biochar amendment, and the biomass increased from 5.83 to 15 g in Zn-contaminated samples. Nutrients such as potassium concentration are directly correlated to the amendment rates, whereas phosphate decreases beyond the 2% biochar amendment rate in both plants. High heavy metal accumulation capacities with improved growth with biochar indicate the sustainability of the process. The translocation factor (TF) > 1 for Zn in NT represents the phytoextraction efficiencies whereas VT indicates high BCF values in the range of 0.5–3.53 for the amended Zn-contaminated soils. The findings indicate that the amendment rate of 2% improves nutrient cycling, plant biomass and heavy metal removal efficiencies. The insights from this study establish that the synergy between biochar amendment and the selected medicinal plants improved the phytoremediation efficiency.

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106. 题目: Enrichment of dissolved metal(loid)s and microbial organic matter during transit of a historic mine drainage system
文章编号: N24090109
期刊: Water Research
作者: Anita Alexandra Sanchez, Karl Haas, Conrad Jackisch, Sabrina Hedrich, Maximilian P Lau
更新时间: 2024-09-01
摘要: Water quality degradation by decommissioned mining sites is an environmental issue recognized globally. In the Ore mountains of Central Europe, a wide array of contaminants is released by abandoned under- and aboveground mining sites threatening the quantity and quality of surface and groundwater resources. Here, we focus on the less-explored internal pollution processes within these mines involving organic carbon and microorganisms in trace metal(loid)s mobilization processes. Over an 18-month period, we conducted hydrological and biogeochemical monitoring at the Reiche Zeche mine, a former lead-zinc-silver mine, in Germany, reaching 230 meters below ground, well below the critical zone. Our results show strong seasonal fluctuations in water availability, concentrations of metal(loid)s, pH, and dissolved organic matter (DOM) components across multiple depths. Excess metal(loid) presence during high flow conditions indicated mobilization behavior deviating from conservative dilution. Our findings reveal strong positive correlations between metal(loid) variability and pH (0.894), and between metal(loid) variability and the DOM fluorescent component C2 (-0.910), a proxy for microbial activity. Accordingly, the microbial processes may significantly contribute to the observed metal(loid) composition and fluxes. By elucidating the intricate roles of hydrological and biogeochemical factors in trace metal(loid) mobilization, our research offers a comprehensive framework for improving mine water management and remediation, potentially informing global environmental policies and sustainable mining practices.

107. 题目: Thermodynamics and explainable machine learning assist in interpreting biodegradability of dissolved organic matter in sludge anaerobic digestion with thermal hydrolysis
文章编号: N24090108
期刊: Bioresource Technology
作者: Jibao Liu, Chenlu Wang, Jiahui Zhou, Kun Dong, Mohamed Elsamadony, Yufeng Xu, Manabu Fujii, Yuansong Wei, Dunqiu Wang
更新时间: 2024-09-01
摘要: Dissolved organic matter (DOM) is essential in biological treatment, yet its specific roles remain incompletely understood. This study introduces a machine learning (ML) framework to interpret DOM biodegradability in the anaerobic digestion (AD) of sludge, incorporating a thermodynamic indicator (λ). Ensemble models such as Xgboost and LightGBM achieved high accuracy (training: 0.90–0.98; testing: 0.75–0.85). The explainability of the ML models revealed that the features λ, measured /, nitrogen to carbon ratio (N/C), hydrogen to carbon ratio (H/C), and nominal oxidation state of carbon (NOSC) were significant formula features determining biodegradability. Shapley values further indicated that the biodegradable DOM were mostly formulas with λ lower than 0.03, measured / value higher than 600 Da, and N/C ratios higher than 0.2. This study suggests that a strategy based on ML and its explainability, considering formula features, particularly thermodynamic indicators, provides a novel approach for understanding and estimating the biodegradation of DOM.

108. 题目: Exploring the influence of different precursor materials on the catalytic performance and deactivation characteristics of iron-loaded biochar catalysts for the catalytic cracking of toluene
文章编号: N24090107
期刊: Science of the Total Environment
作者: Jinzheng Wang, Chao Ye, Haofeng Yang, Zefu Ye, Zhujun Zhu, Haolin Liu, Hui Jin, Xinjia Wang, Jiankai Zhang, Guoneng Li, Yuanjun Tang, Qinhui Wang
更新时间: 2024-09-01
摘要: This study employed rice husks (RH), corn stalks (CS), and camphor leaves (CL) as biomass sources to prepare iron-loaded biochar catalysts, elucidating the key relationships between these biomass materials, their catalytic performance, and their resistance to deactivation in toluene. Experimental results indicated that the carbon deposits in the three spent catalysts are primarily composed of inert carbon (C). The carbon peaks in these deposits primarily consisted of CO, CC, and CO structures, with varying proportions across the different types of spent catalysts. Specifically, the RH spent catalyst exhibited the highest relative content of the CO structure at 13.49 %, the CS spent catalyst showed the highest relative content of the CC structure at 89.19 %, and the CL spent catalyst displayed the highest relative content of the CO structure at 5.57 %. Fe was the predominant species on the surfaces of all three spent catalysts, accounting for over 50 % in each case. FeC was detected on the surfaces of the CS and CL spent catalysts but was absent on the RH spent catalyst. After 80 min of reaction, the carbon deposition rate of the CL catalyst was 8.15 %, with a catalytic cracking efficiency of 28.04 %, making it the most effective overall. This effectiveness was attributed to the CL catalyst's highest oxygen vacancy intensity, where the abundant oxygen source effectively promoted the catalytic reaction of toluene and inhibited carbon deposition. After three consecutive regeneration cycles, the catalytic cracking efficiency of the CL catalyst remained above 70 %, demonstrating strong cyclic regeneration performance. This study provides theoretical insights into the effective utilization of agricultural and forestry waste, contributing to environmental protection.

109. 题目: Eggshell-enhanced biochar with in-situ formed CaO/Ca(OH)2 for efficient removal of Pb2+ and Cd2+ from wastewater: Performance and mechanistic insights
文章编号: N24090106
期刊: Separation and Purification Technology
作者: Jiawen Wu, Xiaonan Sun, Junting Wu, Xue Yu
更新时间: 2024-09-01
摘要: This study proposes a green and simple strategy for efficiently removing heavy metals from wastewater by activating biochar with eggshell and in-situ generating CaO/Ca(OH). Characterization results revealed that the composite carbon material (BCEg15) successfully incorporated CaO/Ca(OH) active sites compared to the raw biochar (BC). Additionally, eggshell activation increased the specific surface area and pore volume of BCEg15 by 4.36 and 6.80 times, respectively, compared to BC. These structural enhancements increased the maximum adsorption capacity of BCEg15 for Pb and Cd by 20.68 and 42 times, respectively, compared to BC. Importantly, the loading of CaO and Ca(OH) significantly enhanced the ion exchange and mineral precipitation capacities of the biochar. For instance, compared to BC, the adsorption capacities of BCEg15 attributed to ion exchange (Q) for Pb and Cd rose by 403.12 mg/g and 197.65 mg/g, respectively, while the adsorption capacities attributed to mineral precipitation (Q) increased by 19.60 times and 45.20 times, respectively. BCEg15 demonstrated excellent reusability, maintaining adsorption capacities of 461.18 mg/g for Pb and 265.26 mg/g for Cd after five cycles. Additionally, BCEg15 outperformed commercial activated carbon in treating heavy metals from desulfurization wastewater from coal-fired power plants, achieving a removal efficiency of 99.98 % compared to 48.22 %. The primary mechanisms by which BCEg15 removes Pb and Cd were identified as ion exchange, mineral precipitation, complexation with oxygen-containing functional groups, and interactions with π electrons. Density functional theory (DFT) was utilized to delve deeper into the microscopic mechanisms of adsorption. The findings showed that the O-top site of CaO exhibited the greatest stability for heavy metal adsorption. Electron density difference maps and partial density of states (PDOS) results revealed a denser electron cloud and greater orbital overlap between CaO and Pb compared to Cd, suggesting a higher affinity and adsorption capacity for Pb, consistent with the experimental findings. This study presents an effective method for preparing adsorbents capable of removing Pb and Cd from wastewater and offers theoretical insights into the adsorption mechanisms of metal oxide-incorporated biochar.

110. 题目: Regulatory roles of extracellular polymeric substances in uranium reduction via extracellular electron transfer by Desulfovibrio vulgaris UR1
文章编号: N24090105
期刊: Environmental Research
作者: Guangming Xu, Haotian Yang, Juncheng Han, Xinyao Liu, Kexin Shao, Xindai Li, Guanying Wang, Weifeng Yue, Junfeng Dou
更新时间: 2024-09-01
摘要: The pathway of reducing U(VI) to insoluble U(IV) using electroactive bacteria has become an effective and promising approach to address uranium-contaminated water caused by human activities. However, knowledge regarding the roles of extracellular polymeric substances (EPS) in the uranium reduction process involving in extracellular electron transfer (EET) mechanisms is limited. Here, this study isolated a novel U(VI)-reducing strain, UR1, with a high uranium removal capacity of 2.75 mM/(g dry cell). Based on a reliable EPS extraction method (45 °C heating), manipulation of EPS in UR1 suspensions (removal or addition of EPS) highlighted its critical role in facilitating uranium reduction efficiency. On the second day, U(VI) removal rates varied significantly across systems with different EPS contents: 60.8% in the EPS-added system, 48.5% in the pristine system, and 22.2% in the EPS-removed system. Characterization of biogenic solids confirmed the reduction of U(VI) by UR1, and the main products were uraninite and UO (2.88–4.32 nm in diameter). As EPS formed a permeable barrier, these nanoparticles were primarily immobilized within the EPS in EPS-retained/EPS-added cells, and within the periplasm in EPS-removed cells. Multiple electroactive substances, such as tyrosine/tryptophan aromatic compounds, flavins, and quinone-like substances, were identified in EPS, which might be the reason for enhancement of uranium reduction via providing more electron shuttles. Furthermore, proteomics revealed that a large number of proteins in EPS were enriched in the subcategories of catalytic activity and electron transfer activity. Among these, iron-sulfur proteins, such as hydroxylamine reductase (P31101), pyruvate: ferredoxin oxidoreductase (A0A0H3A501), and sulfite reductase (P45574), played the most critical role in regulating EET in UR1. This work highlighted the importance of EPS in the uranium reduction by UR1, indicating that EPS functioned as both a reducing agent and a permeation barrier for access to heavy metal uranium.

111. 题目: Adding mineral-enriched biochar to the rhizosphere reduces heavy metal toxicity on plants and soil microbes
文章编号: N24090104
期刊: Journal of Environmental Chemical Engineering
作者: Versha Pandey, Ranu Yadav, Puja Khare
更新时间: 2024-09-01
摘要: In this study, a mineral-enriched (Ca and P) bagasse biochar was synthesized and characterized. The formulation of Ca and P-enriched bagasse biochar (CPB) was examined for immobilizing arsenic (As), cadmium (Cd), and lead (Pb) in rhizospheric soil. The potential of CPB to alleviate heavy metal stress on plants and soil microbial communities was also investigated. The Ca and P-enriched bagasse biochar demonstrated loading of 88 % Ca and 86 % P with improved pore volume, cation exchange capacity, and water-holding capacity. The FTIR and morphology studies demonstrated an increase in surface functionalities on biochar surface and porous morphology. CPB had 1089±21 µm particle size, 1.1 µm pore size, 0.35±0.01 mv PDI, and 20.8±0.2 mv zeta potential, and displayed no phytotoxicity. The application of the CPB in the soil significantly reduced the availability of As, Cd, and Pb in the soil and their uptake in . CPB application altered the subcellular distribution of As, Cd, and Pb in plant tissues. The CPB spray significantly enhanced the biomass (16–27 %), protein (8–44 %), and chlorophyll (15–61 %) contents of . The application of CPB in metal-contaminated soil resulted in an increased relative abundance of the phylum Proteobacteria and the genera , , and in the microbial community structure of the rhizospheric soil. The study suggested that CPB formulation can be used as a potential solution to alleviate different metal uptake and toxicity of crops planted in contaminated soil, improve rhizospheric soil quality, and reconstruct the microbial community structure.

112. 题目: Z-scheme heterojunction Fe-g-C3N4/MoO3-x photocatalyst can effectively activate peroxymonosulfate to degrade humic acid under visible light irradiation
文章编号: N24090103
期刊: Journal of Environmental Chemical Engineering
作者: Fengping Hu, Kangqi Jiang, Zhaochen Liu, Yuying Hu
更新时间: 2024-09-01
摘要: The photo-Fenton-like process is commonly used to degrade organic pollutants in environmental pollution. In this study, a Z-scheme heterojunction Fe-g-CN/MoO photocatalyst was prepared by a calcination-hydrothermal two-step method. The results of photo-Fenton-like degradation of humic acid showed that the FCNM-8/PMS/Vis system achieved a degradation activity of 97.42 % for HA (10 mg/L) within 120 min, which was due to the successful construction of a heterojunction between Fe-g-CN and MoO. The efficient charge separation efficiency and abundant oxygen vacancies on the surface contribute to the Fe/Fe cycle, thereby improving the PMS activation efficiency. The results of free radical quenching and trapping experiments showed that the active species that played a major role in the degradation of HA by photo-Fenton-like were O and h. In addition, the photocatalyst still maintains a removal rate of about 87 % after 5 cycles of repeated use, which means that the prepared sample has good reusability and stability. This work provides a method for designing efficient and stable photocatalysts by constructing heterojunctions and oxygen vacancy regulation strategies.

113. 题目: Impact of straw-biochar amendments on microbial activity and soil carbon dynamics in wheat-maize system
文章编号: N24090102
期刊: Soil and Tillage Research
作者: Jinze Bai, Yuming Huang, Yuxin Bai, Danyang Chen, Shahzad Haider, Jiajie Song, Bruno Rafael De Almeida Moreira, Guangxin Ren, Gaihe Yang, Yongzhong Feng, Xing Wang, Sudhir Yadav
更新时间: 2024-09-01
摘要: Biochar is a promising carbon sequestration strategy, however, the mechanisms underlying the regulation of microbial-derived carbon (M-C) and plant-derived carbon (P-C) in soil organic carbon (SOC) formation and stabilisation remain elusive, constraining accurate predictions of the organic carbon pool. This study examined the soil biotic and abiotic factors that influence the plant and microbial biomarkers in SOC accumulation. A 5-year field experiment was conducted in a temperate wheat-maize agroecosystem in north-western China, with three treatments: (i) no straw incorporation (C), (ii) straw incorporation (S), and (iii) straw incorporation + biochar (SB). The results showed that M-C reached the microbial carrying capacity gradually, whereas P-C was selectively and continuously accumulated, displaying a complementary S-curve pattern. Straw incorporation increased SOC, microbial biomass carbon (MBC), and dissolved organic carbon (DOC) contents, which stimulated microbial richness and enzyme activities, resulting in a 29.1 % and 25.5 % increase in M-C and P-C in SOC, respectively. The stimulated SOC mineralisation (26.2 %) led to significantly lower SOC content in S compared to the SB practice. Biochar combined with straw decreased DOC content (18.5 %) in comparison with straw incorporation, which suppressed microbial and enzyme activities, particularly in Actinobacteriota (12.3 %) and β-N-acetyl-glucosaminidase (24.2 %). It resulted in a 10.9 % and 14.3 % increase in M-C and fungal-to-bacterial necromass carbon ratio (F/B), respectively, while decreasing P-C by 9.6 % over the 5 years. Overall, straw incorporation with biochar effectively enhanced M-C in SOC and reduced SOC mineralisation, suggesting its potential to augment the quantity and stability of SOC pools and mitigate global climate change.

114. 题目: Control of landscape position on organic matter decomposition via soil moisture during a wet summer
文章编号: N24090101
期刊: Soil and Tillage Research
作者: Astrid Françoys, Haichao Li, Orly Mendoza, Kevin Dewitte, Samuel Bodé, Pascal Boeckx, Wim Cornelis, Stefaan De Neve, Steven Sleutel
更新时间: 2024-09-01
摘要: Sustainable cropland management requires preservation of soil organic matter (SOM). In spite of in depth understanding gained from ample field and laboratory studies, we have a poor understanding of landscape scale spatial variation of fresh organic matter (OM) decomposition and its conversion into soil organic carbon (SOC). Particularly, local topographic position may be expected to co-control these processes via soil hydrology. In this study, we sought to identify if such control is significant by setting up a field experiment with two contrasting positions across 10 gently sloping cropland fields covering three different soil texture groups, i.e. loamy sand, (sandy) loam and silt loam. We wanted to link OM decomposition to within-field differences in soil moisture, whilst keeping variation in other soil and management factors minimal. Specifically, mesocosms with C enriched ryegrass (the OM source) were incorporated in the fields for ten weeks and afterwards, soil was separated into > 500 µm, 53 – 500 µm and < 53 µm sized fractions. Overall, we found that lower located positions were wetter than higher positions with average differences of 11 %, 20 % and 16 % in water-filled pore space for the loamy sand, (sandy) loam and silt loam soil, respectively. Mineralization of added OM was surprisingly independent of landscape position, even though moisture conditions appeared wetter than optimal at the low but not at the high landscape positions. Remaining ryegrass residues > 500 µm did follow local topography-driven gradients in soil moisture with higher amounts in low landscape positions. In other words, drier conditions at high landscape positions improved coarse OM decomposition, with consequently more ryegrass-carbon (C) ending up in finer soil fractions (< 500 µm). Additionally, soil texture affected decomposition of the smallest fraction (< 53 µm) with a stabilizing effect for finer-textured (silt loam) soils. We conclude that, despite significant contrasts in moisture conditions between landscape positions, within-field spatial variability of OM mineralization was overall limited during the observed wet summer period. Nevertheless, landscape position affected the quality of remnant unmineralized C, with relatively more conversion of freshly added OM into OM associated with silt and clay at the drier higher positions, potentially improving the long-term stability of SOM. Likewise observations under different weather conditions are needed to evaluate the necessity of precise modelling of local soil hydrology for predicting SOC stock evolution on the landscape scale.

115. 题目: Carbon flows and biochar stability during co-pyrolysis of human faeces with wood biomass
文章编号: N24083120
期刊: Environmental Science: Water Research & Technology
作者: Maria Eleni Koulouri, Mengru Qiu, Michael Templeton, G D Fowler
更新时间: 2024-08-31
摘要: As non-sewered toilets are now the most commonly used sanitation facilities, the faecal sludge management (FSM) sector is starting to be recognised as an important actor for global carbon management. The development of systematic strategies to calculate avoided emissions and carbon storage opportunities are currently constrained by a lack of understanding of carbon flows during faecal sludge treatment. This study investigated carbon sequestration potential for faecal sludge treatment systems that involve co-pyrolysis of human faeces (HF) and wood biomass (WB) at different blending ratios HF:WB (100:0, 75:25, 50:50, 25:75, 0:100) and temperatures (450, 550, 650oC). The systematic investigation of analytical biochar stability parameters and the quantification of carbon flows among pyrolysis products were carried out for the first time in the context of faecal sludge. The stability of the produced biochars was assessed based on their remaining volatility, carbon structure (H/C and O/C ratios, SEM and FTIR analyses) and oxidation resistance (chemical oxidation by H2O2 and thermal degradation by thermogravimetric analysis [R50 index]). Overall, co-pyrolysis of HF and WB improved carbon fixation and biochar stability, enhancing carbon sequestration potential compared to pyrolysis of pure faecal feedstocks. Biochars produced from 50:50 HF:WB blends at 550oC had the highest carbon retention (41.1%); this feedstock blending ratio corresponds to ~30g dry wood added in toilets as a cover material (per user/day), based on the expected daily excretion quantities. For these conditions, low H/C, O/C ratios, H2O2 oxidation and R50 index values suggest that the produced biochars have developed an aromatic structure and are suitable for long-term carbon storage. The biochar characteristics were found to be more dependent on feedstock composition than pyrolysis temperature - provided the temperature reached was sufficient to ensure completion of the main pyrolytic reactions (≥500oC) - while carbon flows to the bio-oil and non-condensable gas fractions were significantly influenced by pyrolysis operational parameters (retention time and inert gas flow rate). The formation of CaCO3 was observed via SEM/EDX and can be further investigated as a potential additional carbon storage mechanism in FSM. The findings of this research can be used to create a methodological dataset to inform carbon assessments and future modelling applications, paving the way towards the establishment of carbon-negative FSM.

116. 题目: Short-term warming decreased soil DOM content and microbial species in alpine wetlands but increased soil DOM content and hydrolase activity in alpine meadows on the Tibetan Plateau
文章编号: N24083119
期刊: Biogeochemistry
作者: Shiyu Fan, Jihong Qin, Hui Sun, Zhenchu Dan, Wenqing Chen, Jiyuan Yang
更新时间: 2024-08-31
摘要:

As important carbon sinks, alpine wetlands on the Tibetan Plateau are undergoing severe degradation. To reveal warming-induced ecological shifts in alpine environments, this study determined soil nutrient contents, enzyme activities, absorption and fluorescence spectra and quadrupole time-of-flight mass spectra (metabolomes) of dissolved organic matter (DOM) and metagenomes based on short-term incubation (0 °C, 10 °C and 20 °C) of topsoil from alpine wetlands and meadows (degraded wetlands). Compared with meadows, wetlands had higher contents of soil DOM (dissolved organic carbon, dissolved organic nitrogen and dissolved phosphorous) and greater activities of hydrolases (β-glucosidase, cellobiohydrolase, β-N-acetylglucosaminidase and acid phosphatase), with those parameters all being highest at 20 °C in meadows and showing various dynamics in wetlands. Soil DOM in wetlands presented the lowest values of specific ultraviolet absorbances (SUVA₂₅₄ and SUVA₂₆₀) at 0 °C and the highest values at 10 °C, whereas the opposite was true in the meadows. Wetland soils had greater diversities of DOM molecular compositions and microbial communities, with warming gradually increasing the number of identified DOM compounds in meadows and decreasing the number of microbial species in both soils. Wetland soils had more Proteobacteria (44.2%) and Acidobacteria (21.1%) and fewer Actinobacteria (18.0%) than meadow soils and contained many temperature-sensitive archaea (which were abundant at 0 °C). Distance-based redundancy analysis and Procrustes analysis indicated the greater complexity of ecological responses in alpine wetlands, which may be attributed to the higher adaptive capacity of soil microbial communities. Our results suggest that both degradation and warming decrease soil DOM content and microbial activities in alpine wetlands, providing important references for alpine wetland conservation under current climate change.

117. 题目: Chironomids regulate long‐chain polyunsaturated fatty acid levels independent of lake nutrient or dissolved organic carbon concentrations
文章编号: N24083118
期刊: Oikos
作者: Matthias Pilecky, Aatu Turunen, Mohammad S Sohrabi, Sadikshya Ghimire, Timo Ilo, Petri Kesti, Simon Vitecek, Lena Fehlinger, Jarkko Akkanen, Sami J Taipale, Anssi Vainikka, Kimmo K Kahilainen, Martin J Kainz, Ursula Strandberg
更新时间: 2024-08-31
摘要: Chironomids are keystone primary benthic consumers with semi‐aquatic life cycles. They support aquatic and terrestrial consumers at higher trophic levels by conveying dietary nutrients, such as fatty acids. In this study, we combined field sampling and laboratory experiments to examine the effects of environmental parameters, including diet, on fatty acid composition and metabolism in chironomid larvae and imagines. Results from 53 lakes showed that lake size, depth, dissolved organic carbon (DOC) concentrations, and trophic state had only marginal effects on the content of long‐chain polyunsaturated fatty acids (LC‐PUFA) in chironomids. Compound‐specific stable hydrogen isotope analyses confirmed that chironomids actively bioconvert dietary fatty acid precursors to LC‐PUFA in all lake types, independent of nutrient or DOC concentrations. Moreover, fatty acid‐specific stable carbon isotope data indicated that the diet of chironomids was subsidized, particularly in oligotrophic lakes in spring, by terrestrial C18 fatty acid precursors that were converted to LC‐PUFA. Data from feeding experiments further confirmed that decreased dietary availability of LC‐PUFA enhanced the conversion of dietary short‐chain precursors to LC‐PUFA. These results suggest that chironomids are PUFA regulators that can sustain LC‐PUFA levels under varying environmental conditions. Furthermore, our results indicate that they bioconvert terrestrial low‐quality material to high‐quality resources, which, via chironomid emergence, support terrestrial food webs. Chironomids are abundant and widespread, and thus, the trophic transfer of LC‐PUFA can have significant implications for the fitness and production of upper trophic level consumers in both aquatic and terrestrial ecosystems.

118. 题目: Redox conditions influence the chemical composition of iron-associated organic carbon in boreal lake sediments: A synchrotron-based NEXAFS study
文章编号: N24083117
期刊: Geochimica et Cosmochimica Acta
作者: Andrew Barber, Yeganeh Mirzaei, Jay Brandes, Azadeh Joshani, Charles Gobeil, Yves Gélinas
更新时间: 2024-08-31
摘要: The global carbon and iron cycles are intimately linked as redox-sensitive iron oxides readily bind organic carbon in a variety of environmental settings, including marine and lacustrine sediments. While these iron-organic carbon complexes sequester vast quantities of organic carbon, the composition of the organic matter within them remains unknown for lacustrine environments. Here we present C K and Fe L edge Near Edge X-ray Absorption Fine Structure (NEXAFS) spectra of surface sediments and authigenic iron complexes from adjacent basins of a pristine boreal lake located in Québec, Canada, with contrasting oxygen exposure regimes. We demonstrate differences in organic carbon speciation in sediments from both basins, as well as co-localization of organic carbon and iron on a sub-micron scale in 100 nm thick samples. Differences in redox cycling across these two basins allow for a direct comparison of the effect of oscillating redox conditions on the composition of organic carbon sequestered by iron. Our results suggest that reactive organic molecules, which may be polysaccharides, were found preferentially associated with iron in the perennially oxic sediments compared to more phenol rich organics in the seasonally anoxic sediments, highlighting the importance of iron oxides in the protection and preservation of labile organic compounds. Traces of aliphatic carbon were observed in sediments from the anoxic basin, alongside carboxyl and aromatic functionalities. This carboxyl-rich aliphatic material could possibly interact with the sediment mineral matrix either through a ligand exchange mechanism between the mineral phases and the carboxyl functionalities, or via non-specific hydrophobic interactions involving the aliphatic moieties. Finally, our work also shows that OC:Fe ratios should be used with caution when inferring a binding mechanism between OC and iron oxides.

119. 题目: Revealing the distribution characteristics and key driving factors of dissolved organic matter in Baiyangdian Lake inflow rivers from different seasons and sources
文章编号: N24083116
期刊: Science of the Total Environment
作者: Kun Shi, Yuting Zhao, Chenbin Wu, Yuting Geng, Shilei Zhou, Beibei Chai
更新时间: 2024-08-31
摘要: The river course is a transitional area connecting the source and receiving water bodies. The dissolved organic matter (DOM) in the river course is an important factor affecting the aquatic environment and ecological health. However, there are shortcomings in studying the differences and quantitative contributions of river DOM in different seasons and sources. In this study, ultraviolet-visible (UV–vis) and three-dimensional fluorescence spectra were used to characterize the optical properties, analyze the spatiotemporal changes, and establish the quantitative relationship between environmental factors and DOM in the inflow rivers of Baiyangdian Lake. The results showed that the relative DOM concentrations in summer and autumn were significantly higher than those in the other seasons ( < 0.001) and that the DOM source ( < 1) was mainly exogenous. The fluorescence abundance of protein-like substances (C1 + C2 + C3) was the highest in spring, whereas that of humus C4 was the highest in autumn. Moreover, the inflow rivers exhibited strong autogenetic characteristics (BIX > 1) throughout the year. Self-organizing maps (SOM) indicated that the main driving factors of water quality were NO-N in spring, autumn, and winter and DO, pH, and chemical oxygen demand (COD) in summer. Random forest analysis showed that the fluorescent components (C1–C4) were closely related to the migration and transformation of nitrogen, and pH and nitrogen were the main predictors of each component. The Mantel test and structural equation model (SEM) showed that temperature and NO-N significantly influenced the DOM concentration, components, and molecular properties in different seasons. Moreover, the river source also affected the distribution mechanism of DOM in the water body. Our study comprehensively analyzed the response of DOM in inflow rivers in different seasons and water sources, providing a basis for further understanding the driving mechanisms of water quality.

120. 题目: A review on the algae-derived biochar catalysts:Advanced oxidation processes and machine learning tools
文章编号: N24083115
期刊: Separation and Purification Technology
作者: Yuchen Chu, Zihao Wang, Wenjun Wang, Yuxi Zeng, Siying He, Chen Yan, Fanzhi Qin, Maihang Wu, Guangming Zeng, Chengyun Zhou
更新时间: 2024-08-31
摘要: Algae have the ability to utilize solar energy to fix carbon, nitrogen, and phosphorus. The conversion of algae into biochar has aroused great interest among researchers. Algal biochar (ABC) has become a formidable alternative in catalysis owing to its oxygen functional groups. In this review, the synthesis method of ABC has been summarized. ABC played a good role in photocatalysis and exhibited excellent performance in persulfate activation. The mechanisms behind the formation of oxidizing species in ABC are further discussed. Fundamentally, the research underscored the feasibility of applying machine learning to enhance ABC yield and pollutant removal. Based on a comprehensive review and driven by big data, the challenges faced by ABC in practical applications and advanced technologies have been identified from multiple perspectives. The direction for future biochar research and ideas for application improvements have been analyzed, promising to provide new approaches for the large-scale application of biochar technology.