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261. 题目: Variations in optical properties of water- and methanol-soluble organic carbon in PM2.5 in Tianjin and Handan over the Wintertime of 2018–2020
文章编号: N24032813
期刊: Atmospheric Research
作者: Haibiao Chen, Ruizhi Zhou, Li Fang, Honglei Sun, Qiaoyun Yang, Hongya Niu, Junwen Liu, Yingze Tian, Min Cui, Caiqing Yan
更新时间: 2024-03-28
摘要: The impact of the Three-year Action Plan for winning the “blue sky defense battle” on the pollution levels and chemical characteristics of fine particulate matter has been intensively studied over the past few years. However, the effect of air pollution control on light absorption of brown carbon remains unclear. In this study, the light absorption and fluorescence properties of water- and methanol-soluble organic carbon (WSOC and MSOC) in PM in Tianjin and Handan in North China Plain were measured and evaluated for three consecutive winters during the Three-year Blue-Sky Action (2018–2020). Overall, the WSOC and MSOC mass concentrations and light absorption coefficients of WSOC and MSOC at 365 nm generally decreased from 2018 to 2020, indicating that the emission of solvent-soluble organic carbon has been effectively controlled with the implementation of pollution abatement measures, such as the enforcement of clean energy policies. The light absorption coefficient and mass absorption efficiency at 365 nm of MSOC were 1.41–3.82 and 1.13–1.72 times higher than that of WSOC, respectively. Fluorescent spectra coupled with parallel factor analysis indicated that less‑/highly‑oxygenated humic-like (LO-/HO-HULIS) and non-N aromatic species (non-Nas) were the major fluorophores in both WSOC and MSOC in the two cities, with LO-HULIS and HO-HULIS as two major contributors to WSOC light absorption, while both HULIS and non-Nas fluorophores had a strong correlation with MSOC light absorption. Correlation analysis with source tracers and fluorescent indices indicated that the influence of combustion emissions remains significant, and secondary formation made a non-negligible contribution to the light absorption and fluorescent components of WSOC and MSOC in both cities. This work will contribute to a better understanding of the evolution of concentration levels and optical properties of WSOC and MSOC during pollution abatement and will inform the subsequent development of measures to achieve a win-win situation for both air quality and climate change.

262. 题目: Effects of dissolved organic matter and halogen ions on phototransformation of pharmaceuticals and personal care products in aquatic environments
文章编号: N24032812
期刊: Journal of Hazardous Materials
作者: Fangyuan Cheng, Tingting Zhang, Hao Yang, Yue Liu, Jiao Qu, Ya-nan Zhang, Willie J G M Peijnenburg
更新时间: 2024-03-28
摘要: Photochemical reactions contribute to the attenuation and transformation of pharmaceuticals and personal care products (PPCPs) in surface natural waters. Nevertheless, effects of DOM and halogen ions on phototransformation of PPCPs remain elusive. This work selected disparate PPCPs as target pollutants to investigate their aquatic phototransformation processes. Results show that PPCPs containing multiple electron-donating groups (–OH, –NH, –OR, etc.) are more reactive with photochemically produced reactive intermediates (PPRIs) such as triplet DOM (DOM⁎), singlet oxygen (O), and reactive halogen species (RHSs), relative to PPCPs containing electron-withdrawing groups (–NOR, –COOR, –OCR, etc.). The generation of RHSs as a result of the coexistance of DOM and halide ions changed the contribution of PPRIs to the photochemical conversion of PPCPs during their migration from fresh water to seawater. For PPCPs (AMP, SMZ, PN, NOR, CIP, etc) with highly reactive groups toward RHSs, the generation of RHSs facilitated their photolysis in halide ion-rich waters, where Cl plays a critical role in the photochemical transformation of PPCPs. Density functional theory (DFT) calculations showed that single electron transfer and H-abstraction are main reaction pathways of RHSs with the PPCPs. These results demonstate the irreplaceable roles of PPRIs and revealing the underlying reaction mechanisms during the phototransformation of PPCPs, which contributes to a better understanding of the environmental behaviors of PPCPs in complex aquatic environments.

263. 题目: KOH-activated biochar and chitosan composites for efficient adsorption of industrial dye pollutants
文章编号: N24032811
期刊: Chemical Engineering Journal
作者: Xu Su, Xuanming Wang, Ziyi Ge, Zhengrong Bao, Li Lin, Yixuan Chen, Wanning Dai, Yuanyuan Sun, Hechong Yuan, Wen Yang, Jun Meng, Hailong Wang, Suresh C Pillai
更新时间: 2024-03-28
摘要: The treatment of dye pollutants remains a challenge in the current management of the water environment. In this study, an innovative biochar material co-modified with KOH and chitosan was synthesized. The morphology and physicochemical properties of the modified biochar material were assessed by SEM, FTIR, XPS, XRD, and thermogravimetric analyses. The results revealed a significant enhancement in chitosan loading due to the pretreatment of biochar with KOH. The co-modified biochar with KOH and chitosan (CHKBC) exhibited an enriched composition of functional groups such as − COOH, −NH, and − OH, leading to a substantial increase in the maximum adsorption of MB by the biochar from 8.83 mg g to 62.04 mg g, a 7.03-fold increase. The excellent adsorption performance of CHKBC for MB was maintained at different solution temperature (288–––318 K) and pH (5–––11) conditions. The main adsorption mechanisms of MB removal by CHKBC involved ion exchange, pore filling, electrostatic attraction, π - π interactions, and hydrogen bonding. Overall, CHKBC has higher chitosan loading, more uniform chitosan distribution, and better adsorption efficiency of MB. It is a promising adsorption material with low cost and a simple production process.

264. 题目: Long-term trends of black carbon and particle number concentrations and their vehicle emission factors in Stockholm
文章编号: N24032810
期刊: Environmental Pollution
作者: Patricia Krecl, Christer Johansson, Michael Norman, Sanna Silvergren, Lars Burman, Eva Maria Mollinedo, Admir Créso Targino
更新时间: 2024-03-28
摘要: Black carbon (BC) and particle number (PN) concentrations are usually high in cities due to traffic emissions. European mitigation policies, including Euro emission standards, have been implemented to curb these emissions. We analyzed BC and PN (particle diameter > 4 nm) concentrations in Stockholm spanning the years 2013–2019 (BC) and 2009–2019 (PN) measured at street canyon and rooftop sites to assess the effectiveness of the implemented policies. Combining these data with inverse dispersion modeling, we estimated BC and PN emission factors (EF and EF) for the mixed fleet, reflecting real-world driving conditions. The pollutants showed decreasing trends at both sites, but PN concentrations remained high at the canyon site considering the World Health Organization (WHO) recommendations. BC concentrations declined more rapidly than PN concentrations, showing a −9.4% and −4.9% annual decrease at the canyon and −7.2% and −0.5% at the rooftop site in the years 2013–2019. The EF and EF trends showed that the mitigation strategies for reducing particulate emissions for on-road vehicles were successful over the study period. However, the introduction of biofuels in the vehicle fleet —ethanol and later rapeseed methyl ester (RME)— increased the concentrations of particles with < 10 nm before the adoption of particulate filters in the exhausts. Stricter Euro emission regulations, especially with diesel particulate filters (DPF) in Euro 5, 6, and VI vehicles, led to 66% decrease in EF and 55% in EF. Real-world EF surpassed HBEFA (Handbook Emission Factors for Road Transport) database values by 2.4–4.8 times; however, direct comparisons between real-world and HBEFA EF are difficult due to differences in lower cut-off sizes and measurement techniques. Our results underscore the necessity for revising the HBEFA database, updating laboratory testing methods and portable emission measuring systems (PEMS) measurements to account for liquid condensate contributions to PN measurements.

265. 题目: Mechanism of organic phosphorus transformation and its impact on the primary production in a deep oligotrophic plateau lake during stratification
文章编号: N24032809
期刊: Water Research
作者: Xiaotong Han, Fan Xun, Xianlong Zhu, Cheng Zhao, Wenlei Luo, Yanru Liu, Man Wang, Di Xu, Shiqiang Wan, Qinglong L Wu, Peng Xing
更新时间: 2024-03-28
摘要: Global warming is leading to extended stratification in deep lakes, which may exacerbate phosphorus (P) limitation in the upper waters. Conversion of labile dissolved organic P (DOP) is a possible adaptive strategy to maintain primary production. To test this, the spatiotemporal distributions of various soluble P fractions and phosphomonesterase (PME)/phosphodiesterase (PDE) activities were investigated in Lake Fuxian during the stratification period and the transition capacity of organic P and its impact on primary productivity were evaluated. The results indicated that the DOP concentration (mean 0.20 ± 0.05 μmol L − 1) was significantly higher than that of dissolved inorganic P (DIP) (mean 0.08 ± 0.03 μmol L − 1) in the epilimnion and metalimnion, which were predominantly composed of orthophosphate monoester (monoester-P) and orthophosphate diesters (diester-P). The low ratio of diester-P / monoester-P and high activities of PME and PDE indicate DOP mineralization in the epilimnion and metalimnion. We detected a DIP threshold of approximately 0.19 μmol L − 1, corresponding to the highest total PME activity in the lake. Meta-analysis further demonstrated that DIP thresholds of PME activities were prevalent in oligotrophic (0.19 μmol L − 1) and mesotrophic (0.74 μmol L − 1) inland waters. In contrast to the phosphate-sensitive phosphatase PME, dissolved PDE was expressed independent of phosphate availability and its activity invariably correlated with chlorophyll a, suggesting the involvement of phytoplankton in DOP utilization. This study provides important field evidence for the DOP transformation processes and the strategy for maintaining primary productivity in P-deficient scenarios, which contributes to the understanding of P cycles and the mechanisms of system adaptation to future long-term P limitations in stratified waters.

266. 题目: Source apportionment of suspended particulate organic matter in a shallow eutrophic lake of Southwest China using MixSIAR model
文章编号: N24032808
期刊: Ecological Indicators
作者: Xu Wang, Wenwen Wen, Wen Guo, Mingguo Wang, Ping Li, Guanshao Yang, Linpei Huang, Guangjie Chen
更新时间: 2024-03-28
摘要: Eutrophication has become prominent in many lakes of the world, resulting in a continuous rise of suspended particulate organic matter (POM) that can be of vital consequence for water quality and carbon cycling. While the accumulation and decomposition of POM can enhance nutrient cycling at a rate depending on the property of lake-water organic carbon, it is important to identify the source of suspended POM for evaluating eutrophication and carbon burial. Here we analyzed the distribution of stable isotopic ratios (C and N) and the carbon/nitrogen ratio (C/N) in suspended POM in a shallow eutrophic lake of subtropical China, for apportioning the POM sources using Bayesian mixing model. Specifically, we collected seasonal samples of lake-water POM (>0.7 μm) from 20 sites in Yilong Lake from September 2020 to June 2022, as well as six types of modern samples covering the main carbon sources in the catchment. The spatial surveys showed that in the dry year (low water level) the C of POM was more enriched in the western basin than those in the central and eastern basins, while the seasonal surveys showed the most enriched C of POM in September. However, this spatio-temporal heterogeneity disappeared in the wet year (high water level). It was also found that the C, N and C/N values of POM varied significantly with those of phytoplankton across sites and seasons. Application of the MixSIAR model further showed that phytoplankton was the predominant source of POM in Yilong Lake (79.8 ± 13.4 %), but with large annual difference, 68.9 ± 10.3 % in the dry year and 90.7 ± 3.7 % in the wet year. In comparison, the contribution of the other five endmembers was much more moderate. In particular, the proportion of allochthonous organic carbon in POM was relatively low, with terrestrial plants and soils contributing 6.1 ± 4.8 % and 4.3 ± 2.5 % of POM, respectively. Our quantitative evidence for the dominance of the autochthonous source (i.e., phytoplankton) in lake-water POM over time and space suggested a determining role of eutrophication in the composition of lake organic carbon. Therefore, the coupling of algal blooms with organic carbon cycling in inland waters can be enhanced with continuous catchment development and regional warming.

267. 题目: Potential retention of dissolved organic matter by soil minerals during wetland water-table fluctuations
文章编号: N24032807
期刊: Water Research
作者: Simin Wang, Ting Liu, Erxiong Zhu, Chen He, Quan Shi, Xiaojuan Feng
更新时间: 2024-03-28
摘要: Wetlands export large amounts of dissolved organic carbon (DOC) downstream, which is sensitive to water-table fluctuations (WTFs). While numerous studies have shown that WTFs may decrease wetland DOC via enhancing DOC biodegradation, an alternative pathway, i.e., retention of dissolved organic matter (DOM) by soil minerals, remains under-investigated. Here, we conducted a water-table manipulation experiment on intact soil columns collected from three wetlands with varying contents of reactive metals and clay to examine the potential retention of DOM by soil minerals during WTFs. Using batch sorption experiments and Fourier transform ion cyclotron resonance mass spectrometry, we showed that mineral (bentonite) sorption mainly retained lignin-, aromatic- and humic-like compounds (i.e., adsorbable compounds), in contrast to the preferential removal of protein- and carbohydrate-like compounds during biodegradation. Seven cycles of WTFs significantly decreased the intensity of adsorbable compounds in DOM (by 50 ± 21% based on fluorescence spectroscopy) and DOC adsorbability (by 2–20% and 1.9–12.7 mg L–1 based on batch sorption experiment), to a comparable extent compared with biodegradable compounds (by 11–32% and 1.6–15.2 mg L–1). Furthermore, oxidation of soil ferrous iron [Fe(II)] exerted a major control on the magnitude of potential DOM retention by minerals, while WTFs increased mineral-bound lignin phenols in the Zoige soil with the highest content of lignin phenols and Fe(II). Collectively, these results suggest that DOM retention by minerals likely played an important role in DOC decrease during WTFs, especially in soils with high contents of oxidizable Fe. Our findings support the ‘iron gate’ mechanism of soil carbon protection by newly-formed Fe (hydr)oxides during water-table decline, and highlight an underappreciated process (mineral-DOM interaction) leading to contrasting fate (i.e., preservation) of DOC in wetlands compared to biodegradation. Mineral retention of wetland DOC hence deserves more attention under changing climate and human activities.

268. 题目: Algal-derived dissolved organic matter accelerates mercury methylation under cyanobacterial blooms in the sediment of eutrophic lakes
文章编号: N24032806
期刊: Environmental Research
作者: Yan Wang, Lan Zhang, Xiang Chen, Cai Li, Shiming Ding, Jiabao Yan, Jing Xiao, Bin Wang, Lv Xu, Xiaoshuai Hang
更新时间: 2024-03-28
摘要: Mercury (Hg), especially in the form of methylmercury (MeHg), poses a significant threat to both organisms and the environment due to its extreme toxicity. While methylation process of Hg in sediments has been extensively studied, recognition of its associated risks and mechanisms during cyanobacterial blooms remains limited. This study investigated the distribution characteristics of Hg and MeHg in sediments of Taihu Lake, China. The concentration of Hg and MeHg varied within the range of 96.0–212.0 ng g−1 and 0.1–0.5 ng g−1, respectively. Higher ecological risks of Hg were found in algal-dominated regions compared to macrophyte areas. The significant correlations observed between Hg, MeHg, and algal-derived dissolved organic matter (ADOM) components C1 and C2 in algal-dominated regions indicate a close association between ADOM components and the Hg methylation process. These components are involved in the absorption or complexation of Hg, participate in redox reactions, and modulate microbial activity. The dsrB gene in sulfate-reducing bacteria (SRB) was found to accelerate the metabolic pathways of Hg methylation. These findings indicate that ADOM could enhance the methylation process of Hg during cyanobacterial blooms, which warrants attention.

269. 题目: Enzyme enhanced lactic acid fermentation of swine manure and apple waste: Insights from organic matter transformation and functional bacteria
文章编号: N24032805
期刊: Journal of Environmental Management
作者: Tianjing Lian, Wanqin Zhang, Qitao Cao, Fubin Yin, Shunli Wang, Tanlong Zhou, Xiaoman Wei, Fangyu Zhang, Zengqiang Zhang, Hongmin Dong
更新时间: 2024-03-28
摘要: Anaerobic co-fermentation is a favorable way to convert agricultural waste, such as swine manure (SM) and apple waste (AW), into lactic acid (LA) through microbial action. However, the limited hydrolysis of organic matter remains a main challenge in the anaerobic co-fermentation process. Therefore, this work aims to deeply understand the impact of cellulase (C) and protease (P) ratios on LA production during the anaerobic co-fermentation of SM with AW. Results showed that the combined use of cellulase and protease significantly improved the hydrolysis during the enzymatic pretreatment, thus enhancing the LA production in anaerobic acidification. The highest LA reached 41.02 ± 2.09 g/L within 12 days at the ratio of C/P = 1:3, which was approximately 1.26-fold of that in the control. After a C/P = 1:3 pretreatment, a significant SCOD release of 45.34 ± 2.87 g/L was achieved, which was 1.13 times the amount in the control. Moreover, improved LA production was also attributed to the release of large amounts of soluble carbohydrates and proteins with enzymatic pretreated SM and AW. The bacterial community analysis revealed that the hydrolytic bacteria and were enriched after enzyme pretreatment, and was the dominant bacteria for LA production. This study provides an eco-friendly technology to enhance hydrolysis by enzymatic pretreatment and improve LA production during anaerobic fermentation.

270. 题目: Enhancing Cd (II) immobilization with thiol-modified low-temperature pyrolysis biochar: Efficiency, mechanism, and applications
文章编号: N24032804
期刊: Journal of Environmental Chemical Engineering
作者: Dongfang Xiang, Zongshun Wang, Chenyang Rao, Xiaying Liu, Fang Fang, Wei Tang, Shaopan Bao, Tao Fang
更新时间: 2024-03-28
摘要: The fixation efficiency of thiol-modified lotus seedpod biochar on Cd (II) was assessed through a comprehensive investigation involving batch experiments and sediment cultivation experiments. The influence of thiol modification on the Cd (II) adsorption performance was investigated under different pyrolysis temperatures (550°C, 700°C, and 850°C). The physicochemical properties, adsorption kinetics, isotherms, and adsorption mechanisms of the modified biochar were studied. Oxidation and thiolation significantly reduced the specific surface area and total pore volume of the biochar, augmenting its hydrophilicity. High-temperature pyrolysis biochar was more suitable for oxidation modification than thiol modification. The abundant oxygen-containing functional groups in low-temperature pyrolysis biochar can serve as active sites for thiol loading. Therefore, it exhibited the highest grafting rate, the highest affinity for Cd (II), and the maximum Cd (II) adsorption capacity of 68mg/g. Thiol-modified biochar primarily immobilized Cd (II) through chelation. Moreover, it significantly reduced the concentration of bioavailable Cd (II) in the sediment and enhanced enzymatic activity. These findings underscore the potential role of low-temperature pyrolysis thiol-modified biochar in addressing Cd (II) pollution in water and sediments.

271. 题目: Unraveling the characteristics of dissolved organic matter removed by aluminum species based on FT-ICR MS analysis
文章编号: N24032803
期刊: Water Research
作者: Yitian He, Peter Jarvis, Xin Huang, Baoyou Shi
更新时间: 2024-03-28
摘要: Given the complexity of dissolved organic matter (DOM) and its interactions with coagulant chemicals, the mechanisms of DOM removal by aluminum (Al) coagulants remains a significant unknown. In this study, six test waters containing DOM with molecular weight (MW, <1 kDa, 1–10 kDa and >10 kDa) and hydrophobicity (hydrophilic, transphilic and hydrophobic) were prepared and coagulated with Al0, Al13 and Al30. The molecular-level characteristics of DOM molecules that were removed or resistant to removal by Al species were analyzed using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The results showed that at the molecular level, saturated and reduced tannins and lignin-like compounds containing abundant carboxyl groups exhibited higher coagulation efficiency. Unsaturated and oxidized lipids, protein-like, and carbohydrates compounds were relatively resistant to Al coagulation due to their higher polarity and lower content of carboxyl groups. Al13 removed molecules across a wider range of molecular weights than Al0 and Al30, thus the DOC removal efficiency of Al13 was the highest. This study furthers the understanding of interactions between Al species and DOM, and provides scientific insights on the operation of water treatment plants to improve control of DOM.

272. 题目: Biochar addition and reduced irrigation modulates leaf morpho-physiology and biological nitrogen fixation in faba bean-ryegrass intercropping
文章编号: N24032802
期刊: Science of the Total Environment
作者: Xuezhi Liu, Weilun Liu, Zhenjuan Su, Junsheng Lu, Peng Zhang, Mengting Cai, Wangcheng Li, Fulai Liu, Mathias Neumann Andersen, Kiril Manevski
更新时间: 2024-03-28
摘要: Intercropping legume with grass has potential to increase biomass and protein yield via biological N-fixation (BNF) benefits, whereas the joint effects of biochar (BC) coupled with deficit irrigation on intercropping systems remain elusive. A N isotope-labelled experiment was implemented to investigate morpho-physiological responses of faba bean-ryegrass intercrops on low- (550 °C, LTBC) or high-temperature BC (800 °C, HTBC) amended sandy-loam soil under full (FI), deficit (DI) and partial root-zone drying irrigation (PRD). LTBC and HTBC significantly reduced intrinsic water-use efficiency (WUE) by 12 and 14 %, and instantaneous WUE by 8 and 16 %, respectively, in faba bean leaves, despite improved photosynthetic (A) and transpiration rate (T), and stomatal conductance (g). Compared to FI, DI and PRD lowered faba bean A, g and T, but enhanced leaf-scale and time-integrated WUE as proxied by the diminished shoots ΔC. PRD enhanced WUE as lower g, T and guard cell length than DI-plants. Despite higher carbon ([C]) and N concentration ([N]) in faba bean shoots amended by BC, the aboveground C- and N-pool of faba bean were reduced, while these pools increased for ryegrass. The N-use efficiency (NUE) in faba bean shoots was reduced by 9 and 14 % for LTBC and HTBC, respectively, but not for ryegrass. Interestingly, ryegrass shoots had 52 % higher NUE than faba bean shoots. The N derived from atmosphere (% Ndfa) was increased by 2 and 9 % under LTBC and HTBC, respectively, while it decreased slightly by reduced irrigation. Quantity of BNF in faba bean aboveground biomass decreased with HTBC coupled with reduced irrigation, mainly towards decreased biomass and soil N uptake by faba bean. Therefore, HTBC might not be a feasible option to improve WUE and BNF in faba bean-ryegrass intercropping, but PRD is permissible as the clear trade-off between BC and PRD.

273. 题目: Effect of long-term compost fertilization on the distribution of organic carbon and nitrogen in soil aggregates
文章编号: N24032801
期刊: Catena
作者: P Gioacchini, E Baldi, D Montecchio, M Mazzon, M Quartieri, M Toselli, C Marzadori
更新时间: 2024-03-28
摘要: Soil fertility is mainly related to soil total organic carbon (C) that should be preserved in order to optimize soil quality and functionality. Consequently, the use of organic amendments could be a possible strategy to increase soil C and nitrogen (N) storage particularly in orchard systems where the disturbance of soil is reduced thus making favorable conditions for C and N stabilization.

274. 题目: Different biochemical composition and oxidation state of soil organic matter between upland and paddy fields
文章编号: N24032720
期刊: Journal of Soils and Sediments
作者: Miao Feng, Kailou Liu, Yilai Lou, Yuntao Shang, Changcheng Guo, Zhaoliang Song, Anna Gunina, Yidong Wang
更新时间: 2024-03-27
摘要: Purpose The chemistry of soil organic matter (SOM) is fundamental for sustainable and climate-smart agroecosystems. However, the differences in SOM chemistry between the upland and paddy soils developing under the same climatic and edaphic conditions are unclear. Materials and methods Py-GC/MS was applied to characterize the biochemical features of SOM in three physical size fractions: coarse particulate (> 0.25 mm, cPOM), fine particulate (0.053–0.25 mm, fPOM), and mineral-associated OM (< 0.053 mm, MAOM) of upland and paddy fields under long-term (> 30 years) mineral and manure fertilizations. Results and discussion Paddy fields had higher contents of soil organic carbon (SOC) and total nitrogen (TN) mainly accumulated in MAOM fraction than uplands. These two soils had different molecular compositions of SOM: N-containing compounds including amino-N and heterocyclic-N compounds enriched in the uplands, whereas paddy had higher proportions of lipids and phenolics. The SOM composition was also dependent on particle size, especially in the uplands, where POM fractions had high contents of lignin and MAOM accumulated N-containing components. In contrast, POM in paddy accumulated polysaccharides, whereas MAOM was enriched with lipids. Particle size controlled the C oxidation state (Cox), and paddy soils had higher Cox than that of uplands, mainly in the MAOM fraction. Conclusions The molecular composition SOM was primarily regulated by land-use type, following by fraction size and fertilization regime, while the Cox was controlled by fraction size. The Cox needs more attention to understand the direction of formation of SOM fractions.

275. 题目: Functions of extracellular polymeric substances in partitioning suspended and sinking particles in the upper oceans of two open ocean systems
文章编号: N24032719
期刊: Limnology and Oceanography
作者: Yosuke Yamada, Akiko Ebihara, Hideki Fukuda, Shigeyoshi Otosaka, Satoshi Mitarai, Toshi Nagata
更新时间: 2024-03-27
摘要: Marine particle dynamics and carbon export, involving extracellular polymeric substances (EPS) like transparent exopolymer particles (TEP) and Coomassie Brilliant Blue-stained particles (CSP), are poorly understood. Although TEP adhesive properties may enhance carbon export by facilitating aggregate formation, their low density can also enhance particle suspension. Factors influencing TEP regulation of particle dynamics remain unclear. To investigate EPS contributions to particle dynamics, we investigated ratios of TEP to particulate organic carbon (POC) and of CSP to POC in suspended and sinking particles collected with marine snow catchers. Samples were collected in a subarctic region near Hokkaido during a spring phytoplankton bloom and in the oligotrophic, subtropical Kuroshio region. At Hokkaido, the mean TEP : POC ratio of sinking particles (0.075 μg Xeq. : μg C) was > 30× lower than in suspended particles (2.3), consistent with a model prediction of selective retention of buoyant TEP-rich particles in the upper water column. In the Kuroshio region, sinking particles also contained fewer TEP than suspended particles; however, the TEP : POC ratio of sinking particles (1.0) was > 10× higher than at Hokkaido, suggesting that TEP constitute a significant carbon component of sinking particles. These findings indicate that TEP facilitate aggregation of high-density particles and particle sinking in the Kuroshio region. Distributions of CSP : POC ratios between suspended and sinking particles resembled TEP : POC ratios in both regions, implying a significant contribution of CSP to particle dynamics. We propose that EPS have divergent effects on suspension and sinking of marine particles, which vary with particle composition and biogeochemical conditions.

276. 题目: Oxidative pyrolysis of spirulina: Impacts of oxygen on bio-oil and property of biochar
文章编号: N24032718
期刊: Journal of Environmental Chemical Engineering
作者: Guoming Gao, Shu Zhang, Yuewen Shao, Chao Li, Lijun Zhang, Wenran Gao, Kuan Ding, Yong Huang, Mortaza Gholizadeh, Xun Hu
更新时间: 2024-03-27
摘要: Externally added oxygen could react with volatiles in oxidative pyrolysis, which might also react with biochar and tailor property of biochar at varied temperatures via distinct ways. This was investigated herein through oxidative pyrolysis of spirulina in a mixture of N/O (11vol%O) at 300 to 600°C. The results suggested that the added oxygen oxidized light volatiles and heavy tar, increasing production of bio-oil while diminishing formation of heavy π-conjugated organics. Oxidation of biochar occurred above 300°C, forming additional oxygen-containing organics but showing little impact on mass yield until 600°C. The excessive oxidation reactions formed oxygen-rich biochar at 300 or 400°C, while the oxygen-containing organics started to be cracked at 500 or 600°C, producing the biochar of fragmented surface. The additional oxygenated organics formed reduced thermal stability of the biochar but improved the overall combustion performance of the resulting biochar at 400°C via lowering ignition temperature and burnout temperature, due to the presence of abundant oxygenated aliphatic structures. The characterization with in-situ IR technique showed that the additional functionalities generated were mainly in the form of -OH, adsorbed CO, C=O, and C-O-C via oxidation of the aliphatic structures, which was less thermally stable than the C-N groups formed through dehydrogenation of amino acid in the oxidative pyrolysis.

277. 题目: Inhibiting effects of humic acid on iron flocculation hindered As removal by electro-flocculation on air cathode iron anode
文章编号: N24032717
期刊: Ecotoxicology and Environmental Safety
作者: Fang Zhang, Hao Zhang, Yue Wu, Yu Xiao, Wan Huang, Jun Tang, Ying Yuan, Jiabao Chen
更新时间: 2024-03-27
摘要: Activated carbon air cathode combined with iron anode oxidation-flocculation synergistic Arsenic (As) removal was a new groundwater purification technology with low energy consumption and high efficiency for groundwater with high As concentration. The presence of organic matter such as humic acid (HA) had ambiguous effects on formation of organic colloids in the system. The effects of the particle size distribution characteristics of these colloids on the formation characteristics of flocs and the efficiency of As purification was not clear. In this work, we used five different pore size alumina filter membranes to separate mixed phase solutions and studied the corresponding changes in iron and arsenic concentrations in the presence and absence of humic acid conditions. In the presence of HA, the arsenic concentration of < 0.05 µm particle size components was 1.01, 1.28, 3.07, 7.69, 2.85 and 1.24 times of that in the absence of HA. At the same time, the arsenic content in 0.05–0.1 µm and 0.1–0.45 µm particle size components was also higher than that in the system without HA, which revealed that the presence of HA hindered the flocculation behavior of As distribution to higher particle sizes in the early stage of the reaction. The presence of HA affected the flocculation rate of iron flocs from small to large particle size fractions and it had limited effect on the behavior of large-size flocs in adsorption of As. These results provide a theoretical basis for targeted, rapid, and low consumption synergistic removal of arsenic and organic compounds in high arsenic groundwater.

278. 题目: Spectroscopic studies of the role of dissolved organic matter in acenaphthene photodegradation in liquid water and ice
文章编号: N24032716
期刊: Environmental Pollution
作者: Shuang Xue, Caihong Jiang, Yingzi Lin, Zhaohong Zhang, Jiyang Liu
更新时间: 2024-03-27
摘要: The effect of concentration and origin of dissolved organic matter (DOM) on acenaphthene (Ace) photodegradation in liquid water and ice was investigated, and the components in DOM which were involved in Ace photodegradation were identified. The DOM samples included Suwannee River fulvic acid (SRFA), Elliott soil humic acid (ESHA), and an effluent organic matter (EfOM) sample. Due to the production of hydroxyl radical (OH) and triplet excited-state DOM (DOM*) which react with Ace, DOM had promotion effects on Ace photodegradation. However, the promotion effects of DOM were prevailed over by their suppressing effect of DOM including screening light effect, intermediates reducing effect and RS quenching effect, and thus, the photodegradation rates of Ace decreased in the presence of the three DOM with concentrations of 0.5–7.5 mg C/L in liquid water and ice. ESHA had higher light absorption and thus had higher screening light effect on Ace photodegradation in liquid water than SRFA and EfOM. At each DOM concentration, ESHA exhibited higher promotion effect on Ace photodegradation than SRFA and EfOM, in liquid water and ice. The binding of Ace with DOM was indicated by decreases in fluorescence intensity of Ace when coexisted with DOM. However, the binding of Ace to DOM played an unimportant role in suppressing Ace photodegradation. The photodegradation behavior of fluorophores in Ace with DOM present in ice was not similar to that in liquid water. C–O, C═O, carboxyl groups O–H and aliphatic C–H functional groups in DOM were involved in the interaction of DOM with Ace. The presence of Ace seemed to have no influence on the photodegradation behavior of functional groups in DOM.

279. 题目: Optimizing Typha biochar with phosphoric acid modification and ferric chloride impregnation for hexavalent chromium remediation in water and soil
文章编号: N24032715
期刊: Chemosphere
作者: Yajun Cai, Jianwei Yang, Zhonglyu Ran, Fantong Bu, Xu Chen, Muhammad Shaaban, Qi-an Peng
更新时间: 2024-03-27
摘要: Considering the persistent and covert nature of heavy metal soil contamination, the sustainable development of ecological environments and food safety is at significant risk. Our study focuses on remediating soils contaminated with chromium (Cr); we introduce an advanced remediation material, iron oxide phosphoric acid-loaded activated biochar (HFBC), synthesized through pyrolysis. This HFBC displays greater microporosity, fewer impurities, and enhanced efficiency for the remediation process. Our research utilized a comprehensive set of analytical techniques, including Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Photoelectron Spectroscopy (XPS), alongside adsorption studies to elucidate the Cr removal mechanism. The effectiveness of HFBC in remediation was influenced by several factors: the pH level, dosage of HFBC, the initial concentration of Cr, and the ambient temperature. Our results indicated an optimal chromium (VI) adsorption capacity of 55.5 mg/g by HFBC at a pH of 6.0 and a temperature of 25 °C, with the process adhering to the pseudo-second-order kinetic model and the Langmuir adsorption isotherm, thus suggesting spontaneity in the uptake method. Moreover, this mechanism encompasses both adsorption and reduction reactions. Using HFBC in pot experiments with cabbage indicated not only an increase in soil pH and cation exchange capacity (CEC), but also a surge in bacterial community abundance. Significant reductions in bioavailable chromium were also recorded. Interestingly, HFBC addition bolstered the growth of cabbage, while concurrently diminishing chromium accumulation within the plant, particularly notable as the HFBC application rate increased. In summation, the HFBC produced in our study has demonstrated convincing efficacy in removing chromium from aqueous solutions and soil. Moreover, the positive agronomic implications of its use, such as enhanced plant growth and reduced heavy metal uptake by plants, indicate its high potential for operational value in the domain of environmental remediation of heavy metals.

280. 题目: Using local ensemble models and Landsat bare soil composites for large-scale soil organic carbon maps in cropland
文章编号: N24032714
期刊: Geoderma
作者: Tom Broeg, Axel Don, Alexander Gocht, Thomas Scholten, Ruhollah Taghizadeh-Mehrjardi, Stefan Erasmi
更新时间: 2024-03-27
摘要: National soil organic carbon (SOC) maps are essential to improve greenhouse gas accounting and support climate-smart agriculture. Large-scale SOC models based on wall-to-wall soil information from remote sensing remain a challenge due to the high diversity of natural soil conditions and the difficulty of accounting for the spatial location of the soil samples. In this study, we tested if the implementation of local ensemble models (LEM) can be used to improve the SOC predictions from Landsat-based soil reflectance composites (SRC) for Germany. For this, we divided the research area into 30 times 30 km tiles and calculated local generalized linear models (GLM) based on random, nearby observations. Based on the GLMs, local SOC maps were predicted and aggregated using a moving window approach. The local variable importance was analyzed to identify spatial dependencies in the correlation between the SRC and SOC. For the final SOC map, a Random Forest (RF) model was trained using the aggregated local SOC predictions, the SRC, and a full set of training samples from the agricultural soil inventory. The results show that the LEM was able to improve the accuracy (R = 0.68; RMSE = 5.6 g kg), compared to the maps based on a single, global model (R = 0.52; RMSE = 6.8 g kg). The local variable importance of the spectral bands showed clear spatial patterns throughout the research area. Differences can be explained by the local soil conditions, influencing the correlation between SOC and the spectral properties. Compared to the widely adopted integration of distance covariates such as geographical coordinates, the LEM was able the reduce the spatial autocorrelation to a greater extent and to improve the prediction accuracy, especially for underrepresented SOC values. The LEM presents a new method to integrate spatial information and increase the interpretability of DSM models.

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