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1. 题目: Response and roles of algal organic matter under copper stress: Spectral and mass spectrometry analysis
文章编号: N24120904
期刊: Science of the Total Environment
作者: Shuqi Wu, Yunkun Qian, Yanan Chen, Jun Guo, Yijun Shi, Dong An
更新时间: 2024-12-09
摘要: Eutrophication leads to various environmental issues, including pollution caused by the production of algal organic matter (AOM). Algae typically respond to environmental changes (e.g., light, temperature, copper [Cu(II)] concentration and pH) by regulating the production and release of different substances, thereby causing unpredictable effects on water quality. We explored the characteristics of AOM and the response mechanisms of algae under Cu(II) stress in the study, using fluorescence spectrum and high-resolution mass spectrometry (HRMS) analysis. The growth of Microcystis aeruginosa was inhibited under Cu(II) stress which was irreversible at Cu(II) concentration ≥ 2 μmol/L. Tryptophan- and humic-like fluorophores were important constituents of extracellular organic matter (EOM), and their contents increased with the addition of Cu(II), indicating that Cu(II) stimulates the production of tryptophan- and humic-like compounds. In addition, fulvic acid-like compounds in EOM were the main components binding to Cu(II) and were overproduced by algae under Cu(II) stress. It was found by HRMS at the molecular level that the formula numbers of EOM generally increased over inhibition time. Under 1 μmol/L Cu(II) stress, nitrogenous compounds (CHON formulae) were the primary AOM, accounting for 37.3–52.0 %. In addition, algae release a large amount of condensed aromatic structures to balance Cu(II) stress. This study provides a molecular-level analysis to explain the variation trends and response mechanisms of algae under various Cu(II) concentrations. The research methods are helpful for utilizing multiple advanced analysis methods to study algae growth and AOM release.

2. 题目: A systematic review of the variability of freshly-emitted and aged black carbon based on various measurement techniques
文章编号: N24120903
期刊: Science of the Total Environment
作者: Bobo Wu, Zichun Wu, Jiahang Dou, Zhiliang Yao, Xianbao Shen, Ao Wang, Long Li, Xuewei Hao
更新时间: 2024-12-09
摘要: Black carbon (BC) poses acute negative health and environmental impacts. Accurate BC quantification is important for assessing its impacts and developing effective control strategies. However, the unclear optical properties and numerous methods of BC restrict its accurate quantification. Elemental carbon (EC), refractory black carbon (rBC), and equivalent black carbon (eBC) are terminology used for BC quantification by various techniques, with an essential parameter of mass absorption cross-section (MAC) characterizing its optical properties. This review summarizes the measurement principles, along with the advantages, limitations, and uncertainties of mainstream instruments used for BC quantification, based on findings from numerous studies. Then, we categorically compared the MAC of BC for different emission sources and regions, and those are not consistent. The MAC values of freshly-emitted and aged BC are both influenced by the combustion sources, while the transport process present significant impact on aged BC. Average MAC values of BC for urban, rural, and other areas are 10.1 ± 3.7 m²/g, 13.4 ± 5.7 m²/g, and 13.7 ± 8.2 m²/g at 550 nm, respectively. Furthermore, we systematically explored the relationship between eBC, EC, and rBC of freshly-emitted and aged BC to establish unambiguous links between these terms. Averaged mass ratios of eBC/EC, eBC/rBC and EC/rBC are 0.81, 0.94, and 1.32 for freshly-emitted BC, 1.17, 2.14, and 1.60 for aged BC, respectively. Overall, it is urgent to establish standard methods for accurate BC quantification in the future to reduce the uncertainty of quantitative results by different techniques.

3. 题目: Deciphering the link between particulate organic matter molecular composition and lake eutrophication by FT-ICR MS analysis
文章编号: N24120902
期刊: Water Research
作者: Minli Guo, Mingxing Yu, Xu Wang, Naidong Xiao, Arnaud Huguet, Yunlin Zhang, Guanglong Liu
更新时间: 2024-12-09
摘要: Eutrophication has emerged as a significant environmental problem for global lakes. As an essential carrier of nutrients, particulate organic matter (POM) plays a vital role in the eutrophication process of these aquatic systems. In this study, POM from seven lakes with different trophic states in the middle and lower reaches of the Yangtze River (China) was characterized using carbon and nitrogen stable isotopes and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The aim was to elucidate the relationship between the source and molecular composition of POM during the eutrophication process of lakes. The results indicated that POM was mainly composed of autochthonous (62.7%) and allochthonous (37.3%) sources, with the contribution from autochthonous sources being more pronounced across the different sources. The POM formulas mainly consisted of the subclasses CHO, CHON, CHOP, CHOS, and CHONS. Notably, CHOP formulas had the highest proportion of labile formula compounds, according for 51.56%. The unsaturation, aromaticity, and oxidation of unique POM formulas gradually decreased with increasing trophic states. A significant positive correlation was observed between CHOP and the percentage of labile compounds (MLB_L%) in unique POM formulas. The relative abundance of lipid and protein compounds of unique POM formulas showed a positive correlation with lake trophic states, which indicated that with the increase of lake trophic states, the content of autochthonous POM gradually increased. Herein, we inferred that with the intensification of lake eutrophication, the autochthonous POM increased, which was accompanied by a further increase of labile P-containing compounds in POM, thus leading to the increasing eutrophication process of lakes in the form of positive feedback. Overall, this investigation of POM at the molecular level illustrates the deep-rooted mechanism of frequent lake eutrophication. This is of great significance in understanding the fate of POM and effectively controlling lake eutrophication.

4. 题目: Marine anoxia impede the transformation of dissolved organic carbon released by kelp into refractory dissolved organic carbon
文章编号: N24120901
期刊: Marine Pollution Bulletin
作者: Lingyun Zhao, Hongyan Xing, Rongyu Xin, Jichen Liu, Huawei Qin, Yuanqing Ma, Zefeng Tian, Mengjie Wang, Yaoyang Ma, Mingliang Zhang
更新时间: 2024-12-09
摘要: The transformation of dissolved organic carbon (DOC) released by macroalgae into refractory dissolved organic carbon (RDOC) through microbial carbon pump (MCP) represents a crucial carbon sequestration process. This process mainly takes place in coastal areas, where it is likely affected by marine anoxia. The interactions between the components of DOC released by kelp and the community structure of heterotrophic bacteria both under normoxic and anoxic conditions were studied by three-dimensional fluorescence parallel factor analysis (PARAFAC), Fourier Transform-Ion Cyclotron Resonance-Mass Spectrometry (FT-ICR-MS) and 16S rRNA high-throughput sequencing. Following 240 days of decomposition, we found that the proportion of labile dissolved organic carbon (LDOC) was 4.61 % greater under anoxic conditions compared to normoxic conditions. Conversely, the proportion of RDOC was 8.06 % lower under anoxic conditions than under normoxic conditions. These findings suggest that anoxia hinders the conversion of LDOC to RDOC in the DOC released by kelp. Although normoxic conditions favor RDOC production, anoxic conditions could be more advantageous for the transport of DOC to the deep ocean, potentially enhancing carbon sequestration. The cultivation of macroalgae in anoxic zones may further boost their carbon sequestration potential.

5. 题目: Characteristics and source apportionment of equivalent black carbon (soot) aerosol over the tropical semi-arid region, Kadapa based on aethalometer measurements
文章编号: N24120815
期刊: Atmospheric Environment
作者: Ramanjula Reddy Annareddy, Pavankumari Sankarayogi, Fasiha Begum Shaik, Balakrishnaiah Gugamsetty, Nazeer Ahammed Yadiki
更新时间: 2024-12-08
摘要: This study investigates equivalent Black Carbon (eBC) and its corresponding impacts, encompassing fossil fuel combustion (eBCff) and biomass combustion (eBCbb), within the tropical semi-arid region of Kadapa (YVU; 14.47°N, 78.82°E, 138 m above sea level). The study was conducted from January 2017 to October 2018. BC varies diurnally and seasonally as a result of regional meteorological conditions and boundary layer dynamics. BC shows a bimodal variation with a peak in the morning (07:00 to 9:00 LT) after sunrise and in the evening (19:00 to 21:00 LT). Throughout the study period, it was observed that the concentration of equivalent Black Carbon (eBC) was elevated during the winter season but lower during the monsoon season. The cumulative average of eBC, eBCff, and eBCbb mass concentrations used for the entire research period were 1.55 ± 0.04, 1.39 ± 0.03, and 0.16 ± 0.004 μg/m3, respectively, with fossil fuel combustion being the primary contributor to the total eBC levels. In the case of eBC correlation with different meteorological parameters; BC is positively correlated with the ambient heating (Tmax-Tmin, oC). MODIS (Moderate Resolution Imaging Spectro radiometer) fire counts and HYSPLIT (Hybrid Single –Particle Lagrangian Integrated Trajectory) trajectory analysis reveals many visible fire counts and long-range transport of air masses. These trajectories are being explored in order to identify black carbon long-range transport sources over the research region.

6. 题目: Mowing in place of conventional grazing increased soil organic carbon stability and altered depth-dependent protection mechanisms
文章编号: N24120814
期刊: Catena
作者: Bin Wei, Yuqi Wei, Hao Zhang, Tongtian Guo, Ruihuan Zhang, Yingjun Zhang, Nan Liu
更新时间: 2024-12-08
摘要: Conventional grazing with high grazing pressure can decrease soil organic carbon (SOC) stability by disrupting its protective mechanisms, eliciting soil depth-dependent responses. Grazing exclusion for hay-making by mowing is usually adopted to restore grassland. However, there is still a lack of systematic evaluation of SOC stability and its impact factors in different soil layers when mowing replaces conventional grazing. Here, based on an investigation of 15 paired sites from mowing vs. conventional grazing in a temperate grassland of northeast China, we found that mowing increased mean weight diameter of soil aggregates (MWD, 5.14 %), Fe/Al associated organic carbon (Fe/Al-OC, 12.20 %), and SOC stability (11.46 %) at topmost soil layer (0–10 cm) but only increased MWD (8.50 %) at subsurface soil (10–30 cm). Mowing increased root biomass of plant variables, soil bulk density and pH of soil properties, and microbial biomass carbon (MBC) of microbial properties at the topmost layer, collectively contributing to SOC protection. However, the reduction in soil nitrate nitrogen and increasing MBC induced by mowing drove the subsurface SOC protection. The protection mechanism for SOC stability shifted from a single physical protection dominance in mowing areas to joint physical and mineral protection in conventional grazing grasslands at the topmost depth. In contrast, subsurface SOC stability was consistently governed by mineral protection regardless of grazing. Our results imply that although grassland ecosystems can initiate more protection mechanisms to cope with disturbances, mowing induced the increase of physical and mineral protection resulting from the substantial promotion in plant C input quantity and microbial biomass, combined with alteration in soil properties, finally stabilized topmost SOC. The limited impact of management practices on the subsurface SOC stability indicates that the interaction of subsurface soil and microbial properties with SOC protection should be fully considered to forecast soil C dynamics and its resistance to disturbance accurately.

7. 题目: Hydrothermal treatment of septic sludge: Revealing temperature-sensitive dissolved organic matter and potential toxicity relationships in the hydrothermal liquid
文章编号: N24120813
期刊: Journal of Environmental Management
作者: Wei Meng, Lei Zheng, Changjun He, Shikun Cheng, Zifu Li
更新时间: 2024-12-08
摘要: Hydrothermal treatment of septic sludge can result in the transfer of significant amounts of dissolved organic matter (DOM) into the hydrothermal liquid (HL). However, there is a lack of research exploring the relationship between temperature-sensitive fractions of DOM in HL and ecological risks. In this study, spectroscopic techniques combining two-dimensional correlation spectroscopy (2D-COS), self-organizing maps (SOM) and structural equation modeling (SEM), respectively, were employed to investigate temperature-sensitive DOM and its potential correlation with phytotoxicity at five process temperatures (180–340 °C). The findings revealed that DOM content peaked at 260 °C, measuring 7625 mg·CL−1. At peak levels, the concentrations of chemical oxygen demand, ammonium nitrogen, total nitrogen, and total phosphorus in the HL reached 16900 mg L−1, 34.8 mg L−1, 1920 mg L−1 and 756 mg L−1, respectively. Results from EEM-PARAFAC-SOM indicated that temperature significantly influences the variations in fluorescent components within DOM. Additionally, 2D-COS analysis identified conjugated structures and critical turning points at 220 °C and 300 °C. Notably, the -CO-NH- functional group, which is closely associated with aromatic protein II, exhibited the highest sensitivity to temperature changes. Wheat seed germination experiments revealed that the DOM sample at 180 °C exhibited the most pronounced inhibition of wheat root length, while demonstrating the least effect on germination. In contrast, seed growth was most severely impaired at 340 °C. SEM analysis revealed the influence of temperature—both direct and indirect—on the properties of DOM, identifying aromatic protein I as the primary determinant limiting seed germination. This research provides valuable insights for the management and utilization of HL.

8. 题目: Application of multi-angle spaceborne observations in characterizing the long-term particulate organic carbon pollution in China
文章编号: N24120812
期刊: Science of the Total Environment
作者: Yun Hang, Qiang Pu, Qiao Zhu, Xia Meng, Zhihao Jin, Fengchao Liang, Hezhong Tian, Tiantian Li, Tijian Wang, Junji Cao, Qingyan Fu, Sagnik Dey, Shenshen Li, Kan Huang, Haidong Kan, Xiaoming Shi, Yang Liu
更新时间: 2024-12-08
摘要: Ambient PM2.5 pollution poses a major risk to public health in China, contributing to significant mortality and morbidity. While overall PM2.5 concentrations have declined in recent years, the changes in PM2.5 chemical constituents remain inadequately understood due to limited ground monitoring networks. We developed a Super Learner model that integrates MISR satellite data, chemistry transport model simulations, and land use information to predict daily OC concentrations across China from 2003 to 2019 at a 10-km spatial resolution. The model achieved high predictive accuracy with a cross-validation R2 of 0.84 and an RMSE of 4.9 μg/m3. Our findings show elevated OC levels in Northern China, driven by industrial activities with concentrations exceeding 30 μg/m3 during the heating season. In contrast, forest fires were the primary contributors in Yunnan, raising OC concentrations to 20–30 μg/m3 during fire seasons. Over the 17-year period, the national OC trend declined by 1.3 % annually. Regionally, the Beijing-Tianjin-Hebei region and the Fenwei Plain experienced faster reductions at annual rates of 1.5 % and 2.0 %, respectively, while Yunnan exhibited no significant trends. To better understand pollution source contributions, we analyzed the OC/EC ratio, which indicated higher ratios in less populated rural areas, suggesting agricultural and biogenic emissions, while lower ratios in urban clusters pointed to primary sources such as traffic and industrial activities. Notably, since 2013, significant decreases in the OC/EC ratio have been observed in the North China Plain, likely reflecting the impact of stringent air pollution control policies on biomass burning. This study provides valuable exposure estimates for epidemiological research on the long-term health effects of OC in China, offering insights for evaluating air quality policies and guiding future management strategies.

9. 题目: Nano-biochar reduces sustainable remediation of cadmium-contaminated soil more than micro-biochar: Evidence from cadmium removal and Eisenia foetida toxicity
文章编号: N24120811
期刊: Environmental Pollution
作者: Ruoyu Yuan, Wei Li, Muhammad Salam, Hong Li
更新时间: 2024-12-08
摘要: Micro- (M-BC) and nano-biochar (N-BC) particles are ready to be disintegrated from biochar (BC), which is extensively applied to remediate heavy metal-contaminated soil. Still, its effects on the remediation efficiency remain poorly understood. This study investigated the interactions between the BC particles (M-BC and N-BC) and Eisenia foetida (E. foetida) in cadmium (Cd)-contaminated soils. Results indicated that M-BC has weak negative effect on E. foetida with survival rates of ≥85% as it is failed to be internalized. The interactive effects between M-BC/N-BC and Cd reduced the mobility of Cd, leading to low avoidance behavior of E. foetida. The synergistic effect of 0.1% M-BC and E. foetida caused pH regulation, BC diffusion and alternation of soil microbial community in the soil. This favored the remediation of Cd-contaminated soils with 56.2% Cd fixation efficiency identified. Conversely, internalization of Cd-loaded N-BC by E. foetida was recorded when 0.1% N-BC was amended in the soil. This triggered DNA damage, antioxidant suppression, antiapoptotic inhibition, digestion impairment, reproductive decline, and survival rates reduction (55%) in E. foetida, indicating the essential role of E. foetida in the soil is likely to be depressed. These findings are helpful to understand the potential negative effects of BC application in soil remediation.

10. 题目: Molecular-level insights into the degradation of dissolved organic matter from cyanobacteria-impacted water by electro-oxidation and electro-Fenton with carbon-based electrodes
文章编号: N24120810
期刊: Journal of Environmental Management
作者: Angga Aji, Fahrudin Sidik, Jr-Lin Lin
更新时间: 2024-12-08
摘要: Algal organic matter (AOM) originating from cyanobacteria-impacted reservoirs presents a significant risk to drinking water. Electrochemical oxidation is an emerging technology effective in AOM degradation. This study focuses on the elimination of AOM, including extracellular organic matter (EOM) and intracellular organic matter (IOM), extracted from Microcystis aeruginosa (MA). Electro-Fenton (EF) and electro-oxidation (EO) techniques were used, with a boron-doped diamond (BDD), a modified graphene-Fe2O3 (GFe) anode, and a graphite felt (GF) cathode. The results showed that BDD and GFe electrodes can effectively degrade AOM, particularly IOM, via EO and EF. BDD with high overpotential exhibited significant IOM degradation via EF, where dissolved organic carbon reduction reached up to 85%. In EO reactions, H2O2 generation by GFe-30 (obtained at the optimal ferric oxide to graphene ratio) is slightly higher than that in BDD, but it cannot fully transform into •OH in the EF process, which inhibits its AOM degradation capability. Furthermore, soluble microbial product-like substances and humics are more effectively degraded by EF and EO using either BDD or GFe. High-molecular weight (>103 Da) fractions, such as biopolymers and humic substances, are principally degraded by both EF and EO regardless of the BDD and GFe anode. This process leads to significant reductions in the haloacetic acids (HAAs) formation potential. EO and EF with GFe-30 are more effective in reducing specific disinfection by-product formation potential during IOM suspension degradation compared to BDD. In conclusion, GFe serves as a novel electrode material to replace BDD as a potent carbon-based anode when utilizing EO or EF treatments for effective AOM removal from cyanobacteria-infested water for drinking water treatment.

11. 题目: Disinfection by-product formation potential in response to seasonal variations in lake water sources: Dependency on fluorescent and molecular weight characteristics
文章编号: N24120809
期刊: Science of the Total Environment
作者: Wenjing Zheng, Yan Chen, Yalin Niu, Pengcheng Xu, Huayi Hao, Bingzhi Dong
更新时间: 2024-12-08
摘要: Seasonal fluctuations present significant challenges to drinking water treatment by altering the properties of Dissolved Organic Matter (DOM) within watersheds, thereby influencing the potential for disinfection by-product (DBP) formation. DOM is a complex mixture of organic matter that serves as a critical DBP precursor and is closely linked to adverse health outcomes. The prediction of DBP formation is complicated by the variability in DOM concentrations and compositions in lake source water, a situation exacerbated by seasonal changes in water systems. We examined the seasonality of lake DBP formation potential (DBPFP) and the dynamics of precursors across four distinct seasons based on water temperature. Utilizing the Excitation-Emission Matrix (EEM) coupled with parallel factorial (PARAFAC) analysis, three-dimensional fluorescence difference spectroscopy (3D-FDS), and molecular weight distribution (MWD), we elucidated the compositions and fates of lake DBP precursors. The findings revealed that DBPFP (THMFP and HAAFP) were markedly influenced by seasonal variations, with peak fluorescence intensity occurring during the summer. Contributions to the water system were dominated by microbial metabolites (region IV) and protein-like substances (region I and region II). 3D-FDS analysis further substantiated the low homogeneity of DBP precursors between summer and autumn, with fulvic acid (FA) substances comprising up to 36.89 % of the variance. Distinct fluorescence intensities were detected at Peak B (266.29 A.U.) and Peak T (376.19 A.U.). Throughout the year, a total of four fluorescent components were characterized, encompassing humic-like substances (C3) and protein-like substances (C1, C2, C4), indicative of biogenic pollution. The source of DBP precursors was identified as small molecular weight organic matter (0.2–5 KDa), resulting from microbial metabolic processes and the degradation of aquatic plants. In addition, external factors such as chlorination, pH levels, and contact time significantly influence THMFP and HAAFP. Overall, these findings advance our comprehension of the transport and fate of DBP precursors within drinking water sources and lake ecosystems. This knowledge is pivotal for optimizing water treatment protocols in relevant water treatment facilities.

12. 题目: Evaluation of nutrient spatial distribution and heavy metal pollution improvement in small-scale farmland under the action of biochar and microbial organic fertilizer
文章编号: N24120808
期刊: Soil and Tillage Research
作者: Zhenyu He, Bo Kang, Leiyu Feng, Yonggao Yin, Jie Yang, Guiqiang Liu, Fusheng Zha
更新时间: 2024-12-08
摘要: Currently, China is undergoing reforms in its rural land transfer policy. As a traditional agricultural country, the operation and management of small-scale farmland serve as the primary economic source for Chinese farmers. However, small-scale farmland is vulnerable to external influences and lacks sufficient risk-resistance capabilities. Developing a low-cost, long-term improvement model is essential for enhancing small-scale farmland.This paper explores the direct integration of biochar and microbial organic fertilizer into the cultivation process of heavy metal-contaminated farmland. The results indicate that the combined application of biochar and microbial organic fertilizer increased soil fertility by 161 % and enhanced the abundance of the antagonistic Chaetomiaceae by 31.6 %. Geostatistical simulations revealed low variation in soil pH, while fertility and water content exhibited high variability. Furthermore, the partial least squares path model confirmed that biochar and organic fertilizer promote.This study elucidates the improvement mechanisms facilitated by biochar and microbial organic fertilizer, providing valuable insights for the management of small-scale farmland in the context of agricultural reform in China.

13. 题目: Organic fertilizer substitution increased soil organic carbon through the association of microbial necromass C with iron oxides
文章编号: N24120807
期刊: Soil and Tillage Research
作者: Yinan Xu, Jing Sheng, Liping Zhang, Guofeng Sun, Jianchu Zheng
更新时间: 2024-12-08
摘要: Organic fertilizer was widely used to enhance the buildup of soil organic carbon (SOC) and microbial necromass C. Iron and aluminum (Fe/Al) oxides serve as critical factors influencing SOC by controlling microbial necromass C. Nevertheless, the alterations and dynamics of microbial necromass C alongside Fe/Al oxides in the presence of organic fertilizer remain poorly elucidated. To evaluate the effect of organic fertilizer substitution for chemical fertilizer on Fe/Al oxides and its relationship to microbial necromass C, a site experiment was initiated in 2010 including three treatments: chemical fertilizer (CF), 50 %CF+ 50 % organic fertilizer (50 % OF), and 100 % organic fertilizer (100 %OF). The data were collected after 4, 8, and 13 years of experiments in 2014, 2018, and 2023, respectively. The results showed that organic fertilizer substitution decreased C loss from microbial mineralization and increased microbial necromass C, and thus contributed to SOC accumulation. With experiment duration, SOC content did not increase from 2018 to 2023 under 100 %OF may be due to C saturation, while microbial necromass still had an increasing trend. In 2023, bacterial and fungal necromass C was increased by 157.4 % and 178.5 % under 50 %OF, and by 230.7 % and 337.8 % under 100 %OF compared with CF, respectively. This suggests that prolonged use of organic fertilizer can enhance the stable SOC. Organic fertilizer increased microbial necromass C mainly through promoting the formation of Fe/Al oxides, and Fe oxides had a more important effect than Al oxides. Overall, we concluded that organic fertilizer substitution increased stable SOC sequestration through the association of microbial necromass C with iron oxides.

14. 题目: Recognizing and reducing effects of moisture-salt coexistence on soil organic matter spectral prediction：From laboratory to satellite
文章编号: N24120806
期刊: Soil and Tillage Research
作者: Danyang Wang, Yayi Tan, Cheng Li, Jingda Xin, Yunqi Wang, Huagang Hou, Lulu Gao, Changbo Zhong, Jianjun Pan, Zhaofu Li
更新时间: 2024-12-08
摘要: Soil organic matter (SOM) mapping in salinized areas is crucial for scientific guidance on soil salinization. However, accurately mapping SOM is challenging due to the intricate interplay between soil moisture content (SMC) and soil salt content (SSC), which significantly influences soil spectra. Unlike prior research that has separately examined the impacts of moisture or salinity, this study delves into the combined effects of these factors on SOM spectra. The objective of this study is to develop and validate several spectral optimization algorithms at both the laboratory and satellite levels. In October 2020, a study was conducted using 291 ground-truth data to examine the impact of various moisture-salt stages (seven moisture stages, five salt stages) on hyperspectral data. Spectrum mechanism responsive for soil moisture and salinity were analyzed through spectral curves, correlation, and analysis of variance (Anova, AOV), and spectrum mechanism responsive for soil moisture and salinity model were built. Following that, the spectra were optimized using piecewise direct normalization (PDS)-AOV, non-negative matrix factorization (NMF)-AOV, and orthogonal signal correction (OSC)-AOV. The SOM prediction models were then built by integrating these optimized spectra with Stacking ensemble machine learning algorithms (RF, GBM, ANN). Eventually, the lab-optimized spectra were merged with satellite multispectral images to create new image (named REC) for SOM mapping. The results indicated varying impacts of SMC and SSC on spectra, particularly between 1400 nm to 2000 nm, revealing the influence of moisture-salt interaction; the best optimization algorithm (OSC-AOV) with Stacking mitigated the effect of moisture-salt coexistence on spectra (the R2 and RPD of the best models elevated by 0.005–0.267, 0.020–0.374 respectively, RMSE reduced by 0.137–1.817 g/kg); implementing this algorithm on REC significantly improved the accuracy of SOM mapping (R2 elevated by 0.185–0.259, RMSE reduced by 2.615–3.203 g/kg). This study extensively investigated the effects of moisture and salinity on spectra, spanning from laboratory to satellite, offering a novel approach to understanding and addressing the complexities in SOM mapping in salinized environments.

15. 题目: Acid-modified corn straw biochar immobilized Pseudomonas hibiscus CN-1 facilitated the bioremediation of carbendazim-contaminated soil
文章编号: N24120805
期刊: Journal of Environmental Management
作者: Yanru Wang, Congling Xu, Qingqing Fan, Hao Li, Yong Yang, Yongquan Zheng, Qingming Zhang
更新时间: 2024-12-08
摘要: Carbendazim application in agroecosystems has posed potential threats to ecosystems and human health. The utilization of biochar-based materials for immobilizing microorganisms offers a sustainable strategy for effective bioremediation. In this study, a novel highly efficient carbendazim-degrading bacterium Pseudomonas hibiscus CN-1 was isolated and immobilized using corn straw-based biochar as a carrier. The effects of degrading strain CN-1, biochar materials, and biochar-CN-1 composite on carbendazim degradation, soil enzyme activities, and community structure diversity were investigated. Under the optimal conditions (pH 6.6, 31 °C, and 6.5% inoculum volume), strain CN-1 metabolized carbendazim into benzimidazole-2-carbamic acid and 2-hydroxybenzimidazole, indicating that demethylation was a major metabolic pathway. Among the biochar materials, acid-modified biochar pyrolyzed at 700 °C proved to be the most effective carrier for strain CN-1 immobilization and efficient removal of carbendazim, achieving a removal rate of 78.7% in water. Compared to the control, the degradation half-lives of carbendazim in the soil with biochar, strain CN-1, and the biochar-strain CN-1 composite were reduced from 30.97 to 23.23, 19.46, and 10.99 days, respectively. Soil enzyme activities and bacterial community diversity results demonstrated that the biochar-strain CN-1 composite not only mitigated the adverse effects of carbendazim on soil enzyme activities but also had the most positive impact on soil microbial richness and diversity. This study highlights the importance of selecting appropriate biochar materials and offers insights into an environmentally friendly method for the efficient bioremediation of soils contaminated with carbendazim.

16. 题目: How grasses stabilize soil organic carbon in aggregates of semi-arid ecologically restored land: Evidence from 13C natural abundance
文章编号: N24120804
期刊: Catena
作者: Vikas Kumar Singhal, Avijit Ghosh, Amit K Singh, Yogeshwar Singh, Siddhartha Sankar Biswas, Deepak Ojha, Ranjan Bhattacharyya
更新时间: 2024-12-08
摘要: Land restoration with grasses is suitable for boosting soil organic carbon (SOC) and biomass productivity. For developing better restoration policies to preserve or increase SOC stock and ecosystem function, a deeper knowledge on the impact of various grasses on SOC dynamics in restored land is required. Here, long-term SOC sequestration was assessed by investigating aggregate-associated carbon (C) and 13C natural abundance following land restoration with Cenchrus ciliaris, Panicum maximum, Chrysopogon fulvus, Heteropogon contortus, Sehima nervosum, and Vetiveria zizanioides grasses in semi-arid India. Among the grasses, C. ciliaris, H. contortus, and S. nervosum improved the proportion of large macroaggregates from 5 to 21 % at the surface and from 1.7 to 12.3 % in the subsurface layer, while the proportion of microaggregates declined significantly (P < 0.05). The higher δ13C values of small macroaggregates (SM) indicated greater C stabilization within the microaggregates under all grasses. The SM could protect ∼22–33 % and 8–15 % of total SOC in land restored with C. ciliaris, H. contortus, and S. nervosum at the surface and the subsurface soil, respectively. However, the roots of C. ciliaris, H. contortus, and S. nervosum contributed to ∼12.66–13.75 % and 2.22–11.24 % of SOC in those layers, respectively. The direction of C transfer was from macroaggregates to microaggregates in soils under C. cilirais, S. nervosum, and H. contortus. This C flow direction could explain greater SOC stabilization than other grasses. The greater amount of aggregate-protected C under these grasses was linked to their greater root biomass, density, and decay rate. In contrast, C transfer from microaggregates to macroaggregates under P. maximum, C. fulvus, and V. zizanioides could result in poor C stabilization. Thus, C. ciliaris, H. contortus, and S. nervosum could be potential options for SOC sequestration in semi-arid ecosystems.

17. 题目: CO₂-enhanced methane production by integration of bamboo biochar during anaerobic co-digestion
文章编号: N24120803
期刊: Journal of Environmental Management
作者: Cristhian Chicaiza-Ortiz, Pengshuai Zhang, Jingxin Zhang, Tengyu Zhang, Qing Yang, Yiliang He
更新时间: 2024-12-08
摘要: This study investigates the enhancement of methane production in anaerobic co-digestion (AcoD) through the introduction of exogenous CO₂ and the application of bamboo biochar. Exogenous CO₂ boosts biogas yield by providing an additional carbon source, which requires optimized solubility and pH buffering to ensure effective methanation. Biochar serves as an electron shuttle and pH stabilizer, facilitating CO2 solubility and syntrophic interactions that enhance microbial stability. When combined, biochar and CO₂ (R2) achieved a significant synergistic effect, increasing specific methane production (SMP) by 42.56% compared to the control (R0). Independent additions of biochar (R1) and CO₂ (R3) also improved SMP, with increases of 35.50% and 28.01%, respectively. This enhancement is likely due to the elevated activity of homoacetogenic bacteria and hydrogenotrophic methanogens, with increased acsB gene expression 2.4-fold with biochar + CO₂ and 1.5-fold with CO₂ alone compared to the control. Additionally, biochar facilitated syntrophic metabolism mediated by Cytochrome-C, promoting electron transfer. The study also demonstrated that biochar and CO2 could enhance enzyme activity, including acetyl-CoA synthase, mhpF, and mhpE. Such improvements bolster AcoD efficiency and promote resource recycling within the circular economy framework.

18. 题目: Forest gaps reduce soil organic carbon stability by decreasing fungal necromass carbon and mineral-associated organic carbon in a calcareous forest
文章编号: N24120802
期刊: Applied Soil Ecology
作者: Wenjing Chen, Kelu Chen, Fuzhong Wu
更新时间: 2024-12-08
摘要: The formation of forest gaps alters the accumulation and stabilization of microbial necromass carbon (C), particularly by affecting its contribution to soil organic C (SOC) stability through the formation of mineral-associated organic C (MAOC), but the available online information is very limited. To understand the mechanism by which forest gaps affect microbial-derived organic matter, microbial DNA sequencing and amino sugar biomarker analysis were integrated. We examined how microbial traits regulate microbial necromass C accumulation from gap center to closed canopy in a subtropical calcareous forest. Our results showed that the formation of forest gaps led to a decline in microbial-derived C, primarily due to a significant reduction in fungal necromass C, which constitutes the majority of microbial necromass C. The establishment of forest gaps resulted in a notable decrease in MAOC, which is closely related to microbial as well as fungal necromass C. This suggests that the disturbance caused by forest gap formation may diminish the microbial (particularly fungal) contribution to the MAOC within subtropical forest ecosystems. Microbial community structure influences microbial necromass C through the specific life history strategies, growth rates, and composition of different microbial taxa. Additionally, microbial taxa differ in their turnover rates and cell wall compositions, affecting how quickly necromass is produced and stabilized in the soil. Variability in these factors directly impacts the overall accumulation and decomposition of necromass C, which in turn affects the formation of MAOC and the stability of SOC. Therefore, the significant contribution of fungal necromass C and the crucial impact of community structure on microbial-derived C accumulation should be considered in earth system models.

19. 题目: Influence of biochar derived from Cd polluted silkworm excrement on the phytoavailability of Cd in a paddy soil and its accumulation in mulberry
文章编号: N24120801
期刊: Ecotoxicology and Environmental Safety
作者: Yongbing Jiang, Xiyun Yang, Shimeng Jiang, Hui Cao, Ming Wang, Zhangbao Li
更新时间: 2024-12-08
摘要: Developing sericulture industry is a promising model for the utilization of soils heavily contaminated with cadmium (Cd), but the management of polluted silkworm excrement (SE) becomes challenging. This study aimed to evaluate the effects of the SE biochar (SB) with Cd (SB-Cd) and without Cd (SB-Cd free) on the chemical properties of paddy soil, the mulberry leaf quality and the accumulation of Cd in mulberry. The soil incubation experiments showed that the two SBs all raised the acidic soil pH (20.24 %∼49.97 %) significantly (P < 0.05) with the increasing SB addition rates. The two SBs increased the soil cation exchange capacity (CEC) and played an essential role in reducing the phytoavailability of Cd. The pot experiment elucidated the two SBs all promoted the growth of mulberry, increased the crude protein content and the chlorophyll content, reduced the total sugar content in leaves. The Cd concentrations in root, stem, leaf were decreased with the increase of SB respectively, but no significant differences were found between the same additions of SB-Cd free and SB-Cd. The use of SB-Cd for remediation of the Cd polluted soils could be a reasonable method to address the Cd polluted SE.

20. 题目: Efficient removal and recovery of phosphate by biochar loaded with ultrafine MgO nanoparticles.
文章编号: N24120715
期刊: Environmental Research
作者: Yanpeng Huang, Qiong Wu, Jingfan Yan, Fumin Chu, Yuming Xu, Dongmin Li, Hongjia Zhang, Sen Yang
更新时间: 2024-12-07
摘要: Biochar loaded with MgO is a promising adsorbent for the removal and recovery of phosphate from aqueous solutions. However, its phosphate adsorption capacity is unsatisfactory, especially at low phosphate concentrations. Loading nanoscale MgO onto biochar is an effective strategy. Here, ultrafine MgO nanoparticles and MgO nanosheets were loaded onto biochar from steam-exploded straw (UMB and SMB) via an impregnation-precipitation-pyrolysis method. The crystal sizes of ultrafine MgO nanoparticles and MgO nanosheets were about 6-8 nm and 10-16 nm, respectively. The phosphate adsorption capacity of UMB at C0=100 mg P L-1 was 219.4 mg P g-1, which was higher than that of SMB (164.9 mg P g-1). The results suggest that surface precipitation was the dominant adsorption mechanism and the hydration process and the smaller particle size of MgO may play a key role in the superior phosphate removal by UMB. Removal tests in real low-concentration phosphate water samples showed that 0.05 g L-1 UMB could reduce the phosphate concentration from 0.17 mg P L-1 to 0.01 mg P L-1. In addition, phosphate could be desorbed from UMB in varying environments, and therefore has the potential to be used in fertilizer production or directly as a slow-release fertilizer.