1. 题目: Microbial and Environmental Processes Shape the Link between Organic Matter Functional Traits and Composition
期刊: Environmental Science & Technology
作者: Ang Hu, Kyoung-Soon Jang, Fanfan Meng, James Stegen, Andrew J Tanentzap, Mira Choi, Jay T Lennon, Janne Soininen, Jianjun Wang
摘要: Dissolved organic matter (DOM) is a large and complex mixture of molecules that fuels microbial metabolism and regulates biogeochemical cycles. Individual DOM molecules have unique functional traits, but how their assemblages vary deterministically under global change remains poorly understood. Here, we examine DOM and associated bacteria in 300 aquatic microcosms deployed on mountainsides that span contrasting temperatures and nutrient gradients. Based on molecular trait dimensions of reactivity and activity, we partition the DOM composition into labile-active, recalcitrant-active, recalcitrant-inactive, and labile-inactive fractions and quantify the relative influences of deterministic and stochastic processes governing the assembly of each. At both subtropical and subarctic study sites, the assembly of labile or recalcitrant molecules in active fractions is primarily governed by deterministic processes, while stochastic processes are more important for the assembly of molecules within inactive fractions. Surprisingly, the importance of deterministic selection increases with global change gradients for recalcitrant molecules in both active and inactive fractions, and this trend is paralleled by changes in the deterministic assembly of microbial communities and environmental filtering, respectively. Together, our results highlight the shift in focus from potential reactivity to realized activity and indicate that active and inactive fractions of DOM assemblages are structured by contrasting processes, and their recalcitrant components are consistently sensitive to global change. Our study partitions the DOM molecular composition across functional traits and links DOM with microbes via a shared ecological framework of assembly processes. This integrated approach opens new avenues to understand the assembly and turnover of organic carbon in a changing world.
2. 题目: New insights into the transformation of effluent organic matter during Fe(II)-assisted advanced oxidation processes: Parallel factor analysis coupled with self-organizing maps
期刊: Water Research
作者: Mo Li, Qinxue Wen, Yongming Zhang, Zhiqiang Chen
摘要: The negative effects of effluent organic matter (EfOM) on receiving aquatic environments and advanced treatment facilities pose significant concerns. However, the effective removal of EfOM is challenging due to its chemically complex nature and its refractory characteristics. In this study, two Fe(II)-assisted oxidation processes including UV/Fe(II)/H2O2 and UV/Fe(II)/persulfate (UV/Fe(II)/PS) were investigated to promote EfOM reduction. Fe(II) was essential for promoting EfOM degradation. The mineralization rate of EfOM increased from 7% to 29% with 2 mM Fe(II) addition in the UV/H2O2 process and to 23% with 0.8 mM Fe(II) addition in the UV/PS process. A preliminary experiment was conducted to obtain the optimal molar ratio of oxidant to Fe(II) for practical applications based on different indicators. The form of Fe(III) prevalent at different pH values strongly affected Fe(II)/Fe(III) cycling, thus determining the progress of EfOM degradation. A machine learning approach consisting of parallel factor analysis coupled with self-organizing maps (PARAFAC-SOM) was employed with fluorescence spectra to visualize the degradation behavior of EfOM in the different reaction systems. Four components (i.e., two humic-like substances, one fulvic acid, and one tryptophan-like substance) were eventually identified, and their reductions reached more than 62% during the Fe(II)-assisted oxidation processes. The degradation orders for each component in the different oxidation processes were initially evaluated by SOM analysis with Fmax percentage data. The degradation behavior of EfOM in the UV/Fe(II)/H2O2 and UV/Fe(II)/PS systems exhibited different trends based on the best matching unit map and component planes. The humic-like component was more refractory than the other three components in both oxidation processes. The microbial humic-like and high-molecular-weight fulvic acid substances showed higher reactivity with SO•4- than with •OH, while the tryptophan-like substance was more reactive in the UV/Fe(II)/H2O2 system than in the UV/Fe(II)/PS system. The outcomes of this study provide new insights into the degradation behavior of EfOM, promoting the development of advanced wastewater treatments.
3. 题目: Estimating remobilization of potentially toxic elements in soil and road dust of an industrialized urban environment
期刊: Environmental Monitoring and Assessment
作者: Fotini Botsou, Ali Sungur, Efstratios Kelepertzis, Zacharenia Kypritidou, Ourania Daferera, Ioannis Massas, Ariadne Argyraki, Konstantinos Skordas, Mustafa Soylak
摘要: The mobility of potentially toxic elements (PTEs) is of paramount concern in urban settings, particularly those affected by industrial activities. Here, contaminated soils and road dusts of the medium-size, industrialized city of Volos, Central Greece, were subjected to single-step extractions (0.43 M HNO3 and 0.5 M HCl) and the modified BCR sequential extraction procedure. This approach will allow for a better understanding of the geochemical phase partitioning of PTEs and associated risks in urban environmental matrices. Based on single extraction procedures, Pb and Zn exhibited the highest remobilization potential. Of the non-residual phases, the reducible was the most important for Pb, and the oxidizable for Cu and Zn in both media. On the other hand, mobility of Ni, Cr, and Fe was low, as inferred by their dominance into the residual fraction. Interestingly, we found a significant increase of the residual fraction in the road dust samples compared to soils. Carbonate content and organic matter controlled the extractabilities of PTEs in the soil samples. By contrast, for the road dust, magnetic susceptibility exerted the main control on the geochemical partitioning of PTEs. We suggest that anthropogenic particles emitted by heavy industries reside in the residual fraction of the SEP, raising concerns about the assessment of this fraction in terms of origin of PTEs and potential environmental risks. Conclusively, the application of sequential extraction procedures should be complemented with source identification of PTEs with the aim to better estimate the remobilization of PHEs in soil and road dust influenced by industrial emissions.
4. 题目: Response of Soil Microbial Community Structure to Phosphate Fertilizer Reduction and Combinations of Microbial Fertilizer
期刊: Frontiers in Environmental Science
作者: Hang Liu, Songsong Li, Ruowen Qiang, Enjia Lu, Cuilan Li, Jinjing Zhang, Qiang Gao
摘要: The excessive application of phosphorus (P) fertilizer is becoming a major agricultural problem, which reduces the utilization rate of the P fertilizer and degrades soil quality. The following five P fertilizer treatments were investigated to know how they affect soil properties, enzyme activity, bacterial and fungal community structure. 1) no P fertilizer (P0); 2) farmers’ traditional P fertilization scheme (FP); 3) 30% reduction in P fertilizer application (P1, microbial blended fertilizer as base fertilizer); 4) 30% reduction in P fertilizer application (P2, diammonium phosphate as starting fertilizer); 5) 30% reduction in P fertilizer application (P3, microbial inoculum seed dressing). The P fertilizer reduction combined with microbial fertilizer significantly increased soil organic matter (SOM), total phosphorus (TP), available phosphorus (AP) available potassium (AK) contents, and acid phosphatase activity (ACP), however, soil urease activity was significantly reduced. Moreover, the P fertilizer reduction combined with microbial fertilizer significantly increased the relative abundance of a potential beneficial genus (i.e., Bacillus , Pseudomonas , Penicillium , and Acremonium ) and potentially pathogenic genus (i.e., Fusarium , Gibberella , and Drechslera ). The structural equation model (SEM) revealed that different P fertilizer reduction systems had significant indirect effects on bacterial and fungal community structures. The results suggested that the P fertilizer reduction combined with microbial fertilizer systems regulated the pathogenic and beneficial genus which created a microbial community that is favorable for maize growth. Moreover, the findings highlighted the importance of soil properties in determining the soil bacterial and fungal community structure.
5. 题目: Selective Organic Carbon Enrichment Influences Nitrous Oxide Reduction by Denitrifiers: Electron Competition Insights
期刊: ACS ES&T Water
作者: Yingrui Liu, Yanying He, Shuqi Ren, Tingting Zhu, Yiwen Liu
摘要: A promising approach to reduce nitrous oxide (N2O) emission from wastewater treatment plants (WWTPs) would be to enrich highly efficient heterotrophic denitrifiers that are capable of regulating N2O reduction. The specific denitrifying community structure could be influenced by the types of organic carbon fed, while their corresponding N2O reduction capacity and electron competition mechanism remain unclear. In this study, the N2O reduction capacity by methanol-, ethanol-, and sodium acetate-enriched denitrifiers was systematically explored at varying carbon-loading rates. The effect of electron competition on N2O reduction was investigated by the combination of the microbial community and biochemical experiments. The results indicated that sodium acetate-enriched denitrifiers harboring abundant N2O reductase (Nos) genes invariably maintained the highest N2O reduction rate (rN2O). However, the concurrent presence of multiple electron acceptors (i.e., NO3– and/or NO2–) resulted in the higher susceptibility of rN2O for sodium acetate-enriched denitrifiers, which could explain the decrease in the N2O reduction rate under sufficient carbon supply. However, under insufficient organic carbon supply, Nos was confronted with fiercer electron competition from the upstream electron pool, causing more N2O accumulation. Moreover, a quantitative investigation of the electron distribution corroborated the aforementioned N2O reduction data. Further studies are warranted to optimize organic carbon-feeding strategies to utilize denitrifiers as an effective N2O sink at WWTPs.
6. 题目: Distribution of terrestrial organic material in intertidal and nearshore marine sediment due to debris flow response efforts
期刊: Science of The Total Environment
作者: H.E. Lowman, M Moingt, A.R. Zimmerman, J.E. Dugan, J.M. Melack
摘要: We examined the distribution and processing of terrestrial organic material, derived from the disposal of material from a massive debris flow event following a major wildfire in a coastal California (USA) catchment in intertidal and nearshore subtidal marine sediments. Organic matter biomarkers, pyrogenic carbon and lignin phenols, were used to trace the distribution of terrestrial debris material in marine environments. In intertidal sediments located <1 km east of the debris deposition site, pyrogenic carbon values did not significantly change and lambda values, a lignin measure, decreased over time, indicating little lateral transport of the disposed material. In subtidal sediment, pyrogenic carbon and lambda values were greatest in 20 m water depths indicating transport and deposition of this material nearshore. An additional lignin measure indicative of degradation suggested terrestrial organic material degradation in subtidal sediment decreased with distance from shore. Terrestrial biomarkers demonstrated that the disposed material was not detected in the top 20 cm of intertidal sediment but was retained in subtidal sediment offshore of the disposal site. Results suggest coastal management should incorporate consideration of the effects of debris disposal activities on nearshore benthic communities and biogeochemical cycling.
7. 题目: Effect of vacuum ultraviolet/ozone pretreatment on alleviation of ultrafiltration membrane fouling caused by algal extracellular and intracellular organic matter
作者: Jinying Du, Chuang Wang, Zhiwei Zhao, Rui Chen, Pengfei Zhang, Fuyi Cui
摘要: Algal blooms in source water can cause algal organic matter (AOM)-related membrane fouling in drinking water treatment. Herein, the effects of vacuum ultraviolet/ozone (VUV/O3) pretreatment on alleviating ultrafiltration membrane fouling caused by AOM, including extracellular organic matter (EOM) and intracellular organic matter (IOM), were investigated systematically. Compared to its sub-processes (UV/O3, O3, VUV, and UV), VUV/O3 pretreatment showed the best performance on AOM removal and membrane fouling mitigation. After VUV/O3 pretreatment, the DOC of EOM and IOM in feed decreased by 51.1% and 26.7%, respectively, and fluorescence components and UV254 of EOM and IOM in feed decreased obviously. Hence, the final specific fluxes of the membranes increased significantly under the impacts of VUV/O3, and VUV/O3 achieved 89.5% and 97.2% mitigation of reversible fouling caused by EOM and IOM, respectively. VUV/O3 pretreatment also reduced the foulants on membrane surface and surface roughness. Moreover, under the effects of reactive oxygen species oxidation, VUV photolysis, and direct O3 oxidation, VUV/O3 decreased organic load and changed the molecular weight distribution, hydrophilicity, and interaction-free energy of AOM, thus mitigating membrane fouling. Furthermore, the effects of O3 dosage and molecular weight cut-off of ultrafiltration membrane on membrane fouling mitigation by VUV/O3 were also investigated. All results highlighted that VUV/O3 pretreatment had huge potential in mitigating AOM-induced membrane fouling.
8. 题目: Adequacy of nitrogen-based indicators for assessment of cropping system performance: A modelling study of Danish scenarios
期刊: Science of The Total Environment
作者: Muhammad Adil Rashid, Sander Bruun, Merete Elisabeth Styczen, Signe Kynding Borgen, Søren Kolind Hviid, Lars Stoumann Jensen
摘要: The EU nitrogen expert panel (EUNEP) has proposed nitrogen-based indicators for farm productivity (N output), efficiency (NUE) and environmental emissions (N surplus). This model-based study (using the Daisy model) was carried out, i) to study the effects of soil type, soil organic matter (SOM), cropping pre-histories varying in C input, 3-to-4 manure-to-mineral N proportions and ten crop rotations on the N-based indicators, and ii) to evaluate the adequacy of these indicators by establishing quantitative relationships between N surplus, N loss and soil organic N (SON) stock change. The results, averaged over 24-year simulation period, indicated that grass-clover dominant rotations had highest N output and showed a tendency to increase SON stocks when compared with spring-cereal monocultures. For most rotations, the NUE ranged between 70 and 75 %. The SON stocks were mainly influenced by initial SOM and cropping prehistory, and stocks increased only under low initial SOM and low C input cropping pre-history (spring barley). Overall, SON stocks tended to increase under low C input pre-history, coarse sand, low initial SOM and high manure N, however, this combination did not result in highest productivity, NUE, and lowest N losses. The relations between N surplus, N loss and SON stock change were strongly affected by crop rotations, emphasizing that using N surplus as an indicator for N leaching/losses while ignoring changes in SON stocks may result in biased conclusions, e.g. estimated average error for N losses ranged from −45 % (underestimation) for maize monoculture to +50 % (overestimation) for continuous grass-clover ley. The results also imply that the environmental assessment of cropping systems must be improved by combining above indicators with estimation of N loss and SON stock changes. This study provides a detailed account of N balance components/N indicators for diverse crop rotations and their use according to the recommendations of the EUNEP.
9. 题目: Conductive biochar promotes oxygen utilization to inhibit greenhouse gas emissions during electric field-assisted aerobic composting
期刊: Science of The Total Environment
作者: Xiang Li, Yan Zhao, Ankun Xu, Huiming Chang, Guangnv Lin, Rong Li
摘要: The insufficient oxygen supply in partial materials commonly results in significant greenhouse gas emissions during composting, which is essentially attributed to the poor electron transfer in the composting systems. Electric field-assisted aerobic composting (EAC) is considered effective in mitigation of greenhouse gas emissions, but the poor conductivity of composting materials hampers its efficiency and applicability. In this study, conductive biochar was added in the EAC system to investigate its effects on the performance and greenhouse gas emissions during the composting processes. In the system of EAC with biochar, the electrochemical properties, O2 utilization and composting performance were improved compared to the systems without biochar or assisted electric field. The maximum current of EAC with biochar was 0.32 A, higher than that without biochar (0.28A). Particularly, the peak concentrations of CH4 and N2O in the EAC system with biochar were 0.86 mg·kg−1 and 1.43 mg·kg−1, which were 45 % and 27 % lower than those in the EAC without biochar, respectively. The direct global warming potential attributed to CO2, CH4, and N2O was 3.96 g CO2-equivalent·kg−1 dry mass, providing a 31.6 % reduction compared to conventional composting. Microbial analyses revealed that biochar increased the relative abundance of electroactive bacteria including Bacillus, Tepidimicrobium and Corynebacterium. In contrast, the abundances of potential nitrifying and denitrifying bacterial species of Pseudomonas, Corynebacterium, Acinetobacter, and Bacillus were significantly lowered in the biochar-assisted EAC system (11.35 %). The results showed that the addition of biochar was able to promote the electrical conductivity of composting materials and accelerate the organic oxidation process by increasing O2 consumption, and accordingly change the dominant microbial community on both composting and biochar particles. This study verified the mechanism of the effectiveness of biochar in greenhouse gas control in composting processes, and thus provided evidence for facilitating the sustainable development of composting technologies.
10. 题目: Ecological networks of dissolved organic matter and microorganisms under global change
期刊: Nature Communications
作者: Ang Hu, Mira Choi, Andrew J Tanentzap, Jinfu Liu, Kyoung-Soon Jang, Jay T Lennon, Yongqin Liu, Janne Soininen, Xiancai Lu, Yunlin Zhang, Ji Shen, Jianjun Wang
摘要: Microbes regulate the composition and turnover of organic matter. Here we developed a framework called Energy-Diversity-Trait integrative Analysis to quantify how dissolved organic matter and microbes interact along global change drivers of temperature and nutrient enrichment. Negative and positive interactions suggest decomposition and production processes of organic matter, respectively. We applied this framework to manipulative field experiments on mountainsides in subarctic and subtropical climates. In both climates, negative interactions of bipartite networks were more specialized than positive interactions, showing fewer interactions between chemical molecules and bacterial taxa. Nutrient enrichment promoted specialization of positive interactions, but decreased specialization of negative interactions, indicating that organic matter was more vulnerable to decomposition by a greater range of bacteria, particularly at warmer temperatures in the subtropical climate. These two global change drivers influenced specialization of negative interactions most strongly via molecular traits, while molecular traits and bacterial diversity similarly affected specialization of positive interactions.
11. 题目: Particulate and dissolved fluorescent organic matter fractionation and composition: Abiotic and ecological controls in the Southern Ocean
期刊: Science of The Total Environment
作者: Miguel Cabrera-Brufau, Cèlia Marrasé, Eva Ortega-Retuerta, Sdena Nunes, Marta Estrada, M Montserrat Sala, Dolors Vaqué, Gonzalo L Pérez, Rafel Simó, Pedro Cermeño
摘要: Phytoplankton-derived organic matter sustains heterotrophic marine life in regions away from terrestrial inputs such as the Southern Ocean. Fluorescence spectroscopy has long been used to characterize the fluorescent organic matter (FOM) pool. However, most studies focus only in the dissolved FOM fraction (FDOM) disregarding the contribution of particles. In order to assess the dynamics and drivers of the dissolved and particulate fractions of FOM, we used a Lagrangian approach to follow the time evolution of phytoplankton proliferations at four different sites in the Southern Ocean and compared the FOM in filtered and unfiltered seawater aliquots. We found that filtration had little effects on FOM visible spectrum fluorescence intensities, implying that most of this signal was due to dissolved fluorophores. On the other hand, protein-like fluorescence was strongly supressed by filtration, with fluorescence of particles accounting for up to 90 % of the total protein-like FOM. Photobleaching was identified as the main driver of visible FDOM composition, which was better described by indices of phytoplankton photoacclimation than by measurements of the incident solar radiation dose. In contrast, protein-like FOM intensity and fractionation were primarily related to abundance, composition and physiological state of phytoplankton proliferations. The chlorophyll a concentration from non-diatom phytoplankton explained 91 % of the particulate protein-like FOM variability. The proportion of protein-like fluorescence found in the dissolved phase was predicted by the combination of potential viral and grazing pressures, which accounted for 51 and 29 % of its variability, respectively. Our results show that comparing FOM measurements from filtered and unfiltered seawater provides relevant information on the taxonomic composition and cell integrity of phytoplankton communities. A better understanding of the commonly overlooked FOM fractionation process is essential for the implementation of in situ fluorescence sensors and will also help us better understand the processes that govern OM cycling in marine systems.
12. 题目: Absolute and Relative Positioning of Natural Organic Matter Acid–Base Potentiometric Titration Curves: Implications for the Evaluation of the Density of Charged Reactive Sites
期刊: Environmental Science & Technology
作者: Marawit Tesfa, Jérôme F L Duval, Rémi Marsac, Aline Dia, Jose-Paulo Pinheiro
摘要: Potentiometric acid–base titration curves collected on humic (nano)particles as a function of pH and salt concentration reflect the electrostatics of the particles and the amount of chemical charges (Q) they carry. In turn, the interpretation of titration data helps quantify their reactivity toward metals provided that both intrinsic chemical and nonspecific electrostatic contributions to proton binding are correctly unraveled. Establishing a titration curve requires several steps, i.e., blank subtraction, relative curve positioning with respect to the electrolyte concentration, and absolute curve positioning achieved by the estimation of particle charge Q0 at low pH. Failure to properly establish each step may lead to the misevaluation of nanoparticle charging behavior. Here, we report (i) a simple procedure to measure and position titration curves for humic substances (HS) versus salt concentration and (ii) an original approach for absolute curve positioning upon the exploitation of proton affinity spectra. The latter do not depend on Q0 and they thus constrain the titration data analysis using the soft Poisson–Boltzmann-based titration (SPBT) formalism for nanoparticles in the thick electric double-layer regime. We illustrate the benefits of our approach by analyzing titration measurements for a large range of humic nanoparticles and by comparing the outcome with results from the literature.
13. 题目: A Novel Way for Hydroxyl Radicals Generation: Biochar-supported Zero-valent Iron Composite Activates Oxygen to Generate Hydroxyl Radicals
期刊: Journal of Environmental Chemical Engineering
作者: Linshuai Duan, Xinhui Liu, Handan Zhang, Fei Liu, Xiqin Liu, Xin Zhang, Lu Dong
摘要: As the cheapest oxidant, it is significant to investigate how to use oxygen to generate hydroxyl radicals (·OH) effectively. Though the oxidation of zero-valent iron (ZVI) by O2 can generate ·OH, the yield is too low for application. Here, we successfully prepared the biochar-supported zero-valent iron composites (BC-ZVI) and applied them to generate ·OH. The ·OH quantitative experiments presented that the BC-ZVI (1:1) has the strongest ability to activate oxygen to generate ·OH among the different mass ratios of BC-ZVI, which can reach 20.19μM at the concentration of 1.0g/L. Materials characterization results demonstrated that the uniform dispersion of ZVI particles and the catalytic capacity of biochar led to the superior performance of BC-ZVI (1:1) in ·OH generation. The O2·- and H2O2 are proved to be the intermediate reactive oxygen species in the generation of ·OH through reactive oxygen species (ROS) capture experiments. Our findings presented that the BC-ZVI (1:1) exhibited high performance in TC removal (186.26mg/g) and the role of ·OH was demonstrated by quenching experiments. Overall, those results indicated that BC-ZVI (1:1) composite could be a promising material to generate ·OH and remove pollutants.
14. 题目: Long-term fertilization enhances soil carbon stability by increasing the ratio of passive carbon: evidence from four typical croplands
期刊: Plant and Soil
作者: Wei Zhou, Shilin Wen, Yunlong Zhang, Andrew S Gregory, Minggang Xu, Syed Atizaz Ali Shah, Wenju Zhang, Honghui Wu, Iain P Hartley
摘要: Aims Soil organic carbon (SOC) plays an important role in improving soil quality, however, how long-term fertilization influences SOC and contrasting active C (AC) and passive C (PC) pools at large scale remains unclear. The aim of this study was to examine the effect of long-term fertilization on SOC, including AC and PC, across four typical croplands in China and to explore the potential relationships and mechanisms. Methods We assessed the effect of chemical fertilizer and manure amendment (standard rate and 1.5 × standard rate of inorganic fertilizer (NPK) with or without manure (M), with a Control for comparison) at three soil depths (0–20 cm, 20–40 cm, 40–60 cm) on SOC, AC and PC. Results We found that SOC, AC and PC increased in the order NPK < NPKM < 1.5NPKM. 1.5NPKM resulting in a significant increase in SOC, AC and PC, of 76.3%, 53.0% and 108.5% respectively across the soil profile (0–60 cm) compared with Control. The response ratio of PC to long-term fertilization was 2.1 times greater than that of AC across four sites on average. In addition, clay was identified as the most important factor in explaining the response of AC and PC to different fertilization application. Conclusions Long-term fertilization enhanced both AC and PC, but the greater response of PC suggests that fertilization application could enhance the stability of C and thus the potential of cropland for SOC accumulation.
15. 题目: Phenolic Content of Aquatic Macrophytes of the Middle Paraná River Floodplain
作者: Gisela Mayora, Berenice Schneider, María Florencia Gutierrez
摘要: Phenolic compounds (PC) of aquatic macrophytes are involved in relevant ecological interactions and ecosystems functions. However, they have been scarcely evaluated in tropical and subtropical floodplains, where hydrological connectivity could be a related variable due to its effects on environmental conditions. Accordingly, we analysed the foliar phenolic content of 16 common aquatic macrophyte species that are native to the subtropical floodplain of the Middle Paraná River to evaluate 1) intraspecific variability in relation with the hydrological connectivity of floodplain habitats; 2) differences among the main life forms occurring in the floodplain; and 3) PC release and production of chromophoric dissolved organic matter (CDOM) from leaves belonging to species characterized by different PC content. No species showed significant differences in PC between individuals collected in connected and isolated habitats. However, emergent macrophytes showed a higher PC content than free-floating macrophytes, which could be related with their higher frequency in isolated habitats. In this regard, biotic interactions, nutrient limitation, and water stress are known to be stronger in isolated habitats, which could favour the establishment of phenolic-rich species due to the beneficial functions of PC under these conditions. Finally, PC release and CDOM production were larger in phenolic-rich species, with the highest values for Ludwigia peploides. The high PC content of L. peploides could have important implications for the functioning of the Middle Paraná floodplain, where it is one of the most conspicuous macrophyte species; and could be involved in the major ecological problems that it causes outside its native distribution range.
16. 题目: High initial soil organic matter level combined with aboveground plant residues increased microbial carbon use efficiency but accelerated soil priming effect
作者: Ninghui Xie, Tingting An, Jie Zhuang, Mark Radosevich, Sean Schaeffer, Shuangyi Li, Jingkuan Wang
摘要: Input of plant residue carbon (C) stimulates microbial growth and activity, and thus may alter native soil organic matter (SOM) mineralization. The partition of plant residue C between microbial growth and respiration, and priming effect on soil organic C (SOC) are affected by initial SOM levels and plant residue types. However, how the interaction between SOM level and plant residue on microbial C use efficiency (CUE) and soil priming effect remains not very clear. Here, we quantified the ratio of plant residue C converted to microbial biomass production (as MBC) over that uptake by microorganism (MBC + respiration) and the priming effect on native SOC in two soils (with low and high initial SOM levels, abbreviated as LSOM and HSOM, respectively) added with 13C-labeled maize residues (root, stem and leaf) through a 180-day incubation. Microbial CUE of maize residue was the highest in the HSOM soil with leaf residue addition, and was the lowest in LSOM soil with stem and leaf residues addition. About 37% ~ 47% of maize residue C was remained in the soil after 180 days. At the end of incubation, the positive cumulative priming effects on native SOC mineralization induced by stem and leaf residues were 23% and 30% stronger (P < 0.05) in the HSOM soil than those of the LSOM soil, respectively. In contrast the root residue addition induced the negative priming effect on native SOC in the two SOM levels of soils. Overall, microbial CUE of maize residue was higher in soil with high initial SOM level, which is likely to promote SOM formation via microbial biomass, although there are many other factors that influence SOM formation. The interactive effect between initial SOM level and plant residue quality should be considered when understanding long-term SOM storage.
17. 题目: Physical fractions of organic matter and mineralizable soil carbon as quality indicators in areas under different forms of use in the Cerrado-Pantanal Ecotone
期刊: Environmental Monitoring and Assessment
作者: Paulo Guilherme da Silva Farias, Camila Beatriz da Silva Souza, Jean Sérgio Rosset, Jefferson Matheus Barros Ozório, Elói Panachuki, Jolimar Antonio Schiavo, Paulo Ricardo Lima, Leandro Marciano Marra
摘要: Understanding soil organic matter (SOM) dynamics is essential to employ management that contribute to the improvement of soil quality (SQ). The aim of this study was to characterize the SOM and evaluate the emission of mineralizable C (C-CO2) in different management systems. The soil was collected in five managed areas: exposed soil (ES), conventional tillage system (CTS), no-tillage system (NTS), permanent pasture (PP) and sugarcane (SC), in addition to a forest area (NF), in the layers of 0–5, 5–10, and 10–20 cm. Total organic carbon (TOC), physical-granulometric fractionation of SOM were performed, determining the contents and stocks of particulate organic matter (C-POM; StockPOM) and mineral organic matter (C-MOM; StockMOM), in addition to calculating SQ indices. In addition to C-CO2 emissions from the soil. The areas of PP and NTS presented the highest levels of TOC in the surface layer. The highest levels of C-MOM and StockMOM were observed in the PP area, besides higher CSI (carbon stock index), reaching 1.67 in the 10–20 cm layer. The areas of PP and SC were similar to the NF in all layers regarding CMI (carbon management index). In CTS, there were higher peaks in emissions and accumulation of C-CO2. It is evident that the improvements in the SQ in the areas of PP, SC, and NTS caused mainly by the deposition of plant material and by soil revolving not being performed. In the CTS, high emission peaks of C-CO2 show that the lack of conservation management practices contributes to the emission of greenhouse gases.
18. 题目: Integrated organic and inorganic fertilization and reduced irrigation altered prokaryotic microbial community and diversity in different compartments of wheat root zone contributing to improved nitrogen uptake and wheat yield
期刊: Science of The Total Environment
作者: Chao Wang, Haiyang Ma, Zhihan Feng, Zhenxing Yan, Bolong Song, Jialong Wang, Yuyin Zheng, Weiping Hao, Wenying Zhang, Minjie Yao, Yaosheng Wang
摘要: The effect of long-term water and integrated fertilization on prokaryotic microorganisms and their regulation for crop nutrient uptake remains unknown. Therefore, the impact of soil water and integrated fertilization after eight years on prokaryotic microbial communities in different compartments of root zone and their association with wheat nitrogen (N) absorption and yield were investigated. The results showed that compared with fertilization treatments (F), water regimes (W) more drastically modulated the prokaryotic microbial community structure and diversity in bulk soil, rhizosphere and endosphere. The increase of irrigation improved the prokaryotic diversity in the rhizosphere and endosphere while decreased the diversity in the bulk soil. Application of organic fertilizers significantly improved soil organic matter (SOM) and nutrient contents, increased rhizosphere and endophytic prokaryotic microbial diversity, and elevated the relative abundance of aerobic ammonia oxidation and nitrification-related functional microorganisms in rhizosphere and endosphere. Increasing irrigation elevated the relative abundance of functional microorganisms related to aerobic ammonia oxidation and nitrification in the rhizosphere and endosphere. Soil water content (SWC) as well as NH4+-N and NO3−-N were key predictors of prokaryotic microbial community composition under W and F treatments, respectively. Appropriate application of irrigation and organic fertilizers increased the relative abundance of some beneficial bacteria such as Flavobacterium. Water and fertilization treatments regulated the prokaryotic microbial communities of bulk soil, rhizosphere and endosphere by altering SWC and SOM, and provided evidence for the modulation of prokaryotic microorganisms to promote nitrogen uptake and wheat yield under long-term irrigation and fertilization. Conclusively, the addition of organic manure (50 %) with inorganic fertilizers (50 %) and reduced amount of irrigation (pre-sowing and jointing-period irrigation) decreased the application amount of chemical fertilizers and water, while increased SOM and nutrient content, improved prokaryotic diversity, and changed prokaryotic microbial community structure in the wheat root zone, resulting in enhanced nutrient uptake and wheat yield.
19. 题目: Novel Solar-Driven Ferrate(VI) Activation System for Micropollutant Degradation: Elucidating the Role of Fe(IV) and Fe(V)
期刊: Journal of Hazardous Materials
作者: Jiamin Mai, Tao Yang, Jun Ma
摘要: This paper presents a novel process of solar-ferrate(VI) [Fe(VI)] for micropollutant degradation. The solar-Fe(VI) process promoted micropollutant degradation compared with Fe(VI) alone and solar. The radical scavenging and probing experiment results suggested that Fe(V) and Fe(IV) but not reactive oxygen species were most likely involved in the solar-Fe(VI) process. Through building a kinetic model, Fe(IV) and Fe(V) were observed to play an equally significant role in the solar-Fe(VI) process. Afterward, the reaction mechanism of the photochemistry of Fe(VI) was elaborated. Fe(IV) formed from Fe(VI) photolysis and then decomposed to Fe(II) which reacted with Fe(VI) to form Fe(V). Furthermore, the effect of pH on carbamazepine (CBZ) degradation was studied and the quantum yields of Fe(VI) were determined, with (1.98±0.16)×10-3 mol∙einstein-1, (5.90±0.27)×10-4 mol∙einstein-1, and (1.66±0.14)×10-4 mol∙einstein-1 at pH 7.0, 8.0, and 9.0, respectively. Inorganic ions, including Cl-, HCO3-, and Br- displayed negligible influence on the CBZ degradation, whereas humic acid inhibited the CBZ degradation. Finally, the solar-Fe(VI) process exhibited good applicability in authentic waters and under different irradiation (natural sunlight, ultraviolet light, and visible light from solar cut-off emission). Overall, this study provides a new routine for efficient micropollutant elimination and reveals the photochemistry of Fe(VI).
20. 题目: Machine Learning Assisted Prediction of Biochar Yield and Composition via Pyrolysis of Biomass
期刊: Bioresource Technology
作者: Yize Li, Rohit Gupta, Siming You
摘要: Biochar production via pyrolysis of various organic waste has potential to reduce dependence on conventional energy sources and mitigate global warming potential. Existing models for predicting biochar yields and composition are computationally-demanding, complex, and have low accuracy for extrapolative scenarios. Here, two data-driven machine learning models based on Multi-Layer Perceptron Neural Network and Artificial Neuro-Fuzzy Inference System are developed. The data-driven models predict biochar yield and compositions for a variety of input feedstock compositions and pyrolysis process conditions. Feature importance assessment of the input dataset revealed their competitive significance for predicting biochar yields. Overall, the predictive accuracy of the models was up to 12.7% better than the Random Forest and eXtreme Gradient Boosting machine learning algorithms reported in the literature. The models developed are valuable for environmental footprint assessment of biochar production and rapid system optimization.