41. 题目: Molecular composition and chemodiversity of dissolved organic matter in wastewater sludge via Fourier transform ion cyclotron resonance mass spectrometry: Effects of extraction methods and electrospray ionization modes
期刊: Water Research
作者: Peipei Zhao, Zhengliang Du, Qinglong Fu, Jing Ai, Aibin Hu, Dongsheng Wang, Weijun Zhang
摘要: High-resolution mass spectrometry was extensively applied in molecular composition and transformation pathways of dissolved organic matter (DOM) in wastewater sludge treatments. Sample pretreatment methods and electrospray ionization (ESI) modes significant affect the accuracy of molecular characterization for DOM. This study investigated the effects of pretreatment methods (styrene divinyl benzene polymer (PPL), octadecyl (C18), and electrodialysis (ED)) on molecular characteristics of DOM in two typical wastewater sludges (waste activated sludge (WAS) and anaerobic digestion sludge (ADS)) analyzed by FT-ICR MS in both positive ESI (ESI (+)) and negative ESI (ESI (−)) modes. The results indicated that ED pretreatment exhibited the highest recovery rate of 70% ‒ 95% for sludge-derived DOM. ED and PPL performed well in recovering the different sludge-derived DOM with a high similarity of molecular characteristics (e.g., lipids, proteins/aliphatic, and lignins/CRAM-like), and the C18 method was ineffective in extracting carbohydrates, unsaturated hydrocarbons, and amino sugars. In addition, compared with single ESI (−) analysis mode, the molecular number identified by ESI (+) analysis mode was increased by 200%, especially, more unsaturated hydrocarbons and N-containing compounds were detected. Except for biogenic DOM, plenty of emerging containments (ECs) in sludge-derived DOM were identified; ESI (−) mode was more effectively in recognizing the alkyl benzene sulfonic acids (e.g., anionic surfactants); and ESI (+) mode was more effectively for plasticizers identification, for example, dioctyl terephthalate and dibutyl phthalate. This study illustrated that ED pretreatment coupled with FT-ICR MS in dual ESI modes could give more insights in complexed molecular information for DOM in wastewater sludge, and provides a theoretical basis for subsequent sludge treatments and disposals.
42. 题目: Environmental Factors Influence the Effects of Biochar on the Bioavailability of Cd and Pb in Soil Under Flooding Condition
期刊: Water, Air, & Soil Pollution
作者: Honghong Li, Zhou Li, Limei Huang, Xiaoming Mao, Yuxuan Dong, Shilong Fu, Rong Su, Yihan Chang, Chuan Zhang
摘要: Biochar, as a sustainable amendment, effectively remediates soils contaminated with potentially toxic metals. However, the immobilization efficiencies of biochar can vary according to the soil properties. To investigate the critical impact factor of soil properties on the immobilization of cadmium (Cd) and lead (Pb) in soil by biochar, this study was conducted with an incubation batch experiment and a pot experiment by using an acid soil sample (soil A), a weakly acidic soil sample (soil B), and an alkaline soil sample (soil C). The results showed that the CaCl2-extracted Cd in the three soil samples was reduced by 15.2% (soil A), 44.3% (soil B), and 22.0% (soil C) with biochar application, and the decrease rate of the available Cd concentration is significantly negatively (P < 0.05) related with soil pH, cation exchange capacity, and the proportion of illite and illite–smectite mixed layers of clay minerals. Biochar significantly reduced the soil available Pb concentration of soil A, soil B, and soil C by 57.2%, 52.3%, and 40.3%, respectively. And the decreased rate of available Pb concentration is significantly negatively related to soil pH and soil organic materials (P < 0.05). The Cd concentration of rice shoots is positively related to the amount of iron plaque. Biochar application decreased the formation of iron plaque on rice roots grown in soils A and B due to the biochar slowing down the decreasing trend of the redox potential during flooding. However, biochar increased the amount of iron plaque on rice roots grown in soil C, which had a higher pH. As a result, biochar reduced the accumulation of Cd and Pb in rice shoots and promoted the biomass of rice grown in soils A and B (acid soils) but had the opposite effect on soil C (an alkaline soil). Graphical
43. 题目: Nanoscale characterization of the sequestration and transformation of silver and arsenic in soil organic matter using atom probe tomography and transmission electron microscopy
期刊: Environmental Science: Processes & Impacts
作者: Mozhgan Akbari Alavijeh, Michael Schindler, Mark G Wirth, Odeta Qafoku, Libor Kovarik, Daniel E Perea
摘要: This study investigates the sequestration and transformation of silver (Ag) and arsenic (As) ions in soil organic matter (OM) at the nanoscale using the combination of atom probe tomography (APT), transmission electron microscopy (TEM), focused ion beam (FIB), ion mill thinning and scanning electron microscopy (SEM). Silver-arsenic contaminated organic-rich soils were collected along the shore of Cobalt Lake, a former mining and milling site of the famous Ag deposits at Cobalt, Ontario, Canada. SEM examinations show that particulate organic matter (OM grains) contains mineral inclusions composed of mainly Fe, S, and Si with minor As and traces of Ag. Four OM grains with detectable concentrations of Ag (by SEM-EDS) were further characterized with either a combination of TEM and APT or TEM alone. These examinations show that As is predominantly sequestered by OM through either co-precipitation with Fe-(hydr)oxide inclusions or adsorption on Fe-(hydr)oxides and their subsequent transformation into scorodite (FeAsO4·2H2O)/amorphous Fe-arsenate (AFA). Silver nanoparticles (NPs) with diameters in the range of ∼5–20 nm occur in the organic matrix as well as on the surface of Fe-rich inclusions (Fe-hydroxides, Fe-arsenates, Fe-sulfides), whereas Ag sulfide NPs were only observed on the surfaces of the Fe-rich inclusions. Rims of Ag-sulfides on Ag NPs (TEM data), accumulation of S atoms within and around Ag NPs (APT data), and the occurrence of dendritic as well as euhedral acanthite NPs with diameters in the range of ∼100–400 nm (TEM data) indicate that the sulfidation of the Ag NPs occurred via a mineral-replacement reaction (rims) or a complete dissolution of the Ag NPs, the subsequent precipitation of acanthite NPs and their aggregation (dendrites) and Ostwald ripening (euhedral crystals). These results show the importance of OM and, specifically the mineral inclusions in the sequestration of Ag and As to less bioavailable forms such as acanthite and scorodite, respectively.
44. 题目: Source apportionment of black carbon aerosols in winter across China
期刊: Atmospheric Environment
作者: Hong-Wei Xiao, Yu Xu, Hua-Yun Xiao
摘要: Black carbon (BC) aerosols emitted from incomplete combustion of fossil fuels, biofuels, and biomass have significant effects on the environment and human health. Combustion-derived BC aerosols are an important component in haze pollution. High concentrations of BC aerosols were found in fine particulate matter (PM2.5) in China, and source apportionment was the strategy underpinning targeted mitigation actions. Here, we present a Bayesian statistical model, a three-dimensional array of a stable carbon isotope (δ13C) and the ratios of non-sea-salt K+ to BC (nss-K+/BC) and ΔBC/ΔCO that is a reasonably inexpensive and rapid way to constrain BC source apportionments. This study analyzed 551 daily PM2.5 samples collected in January 2018 in 18 large cities and at 1 remote site scattered across China. The results show that BC concentrations were generally higher in cities in northern China than they were in cities in southern China. Source apportionments indicate that BC in 44% of cities was mainly from liquid fuel combustion. In other sites, including 39% of cities, one suburban site, and one remote site, BC was mainly from biomass burning. These findings suggest that to improve air quality, the Chinese government should further strengthen controls on liquid fuel combustion and consider controlling biomass burning.
45. 题目: Synergistic Effects of Rice Husk Biochar and Aerobic Composting for Heavy Oil-Contaminated Soil Remediation and Microbial Community Succession Evaluation
期刊: Journal of Hazardous Materials
作者: Yuanfei Lv, Jianfeng Bao, Dongyang Liu, Xinxin Gao, Yunjiang Yu, Liandong Zhu
摘要: Soil petroleum pollution is an urgent problem in modern society, which seriously threatens the ecological balance and environmental safety. Aerobic composting technology is considered economically acceptable and technologically feasible for the soil remediation. In this study, the combined experiment of aerobic composting with the addition of biochar materials was conducted for the remediation of heavy oil-contaminated soil, and treatments with 0, 5, 10 and 15wt% biochar dosages were labeled as CK, C5, C10 and C15, respectively. Conventional parameters (temperature, pH, NH4+-N and NO3--N) and enzyme activities (urease, cellulase, dehydrogenase and polyphenol oxidase) during the composting process were systematically investigated. Remediation performance and functional microbial community abundance were also characterized. According to experimental consequences, removal efficiencies of CK, C5, C10 and C15 were 48.0%, 68.1%, 72.0% and 73.9%, respectively. The comparison with abiotic treatments corroborated that biostimulation rather than adsorption effect was the main removal mechanism during the biochar-assisted composting process. Noteworthy, the biochar addition regulated the succession process of microbial community and increased the abundance of microorganisms related to petroleum degradation at the genus level. This work demonstrated that aerobic composting with biochar amendment would be a fascinating technology for petroleum-contaminated soil remediation.
46. 题目: The uptake of selenium by perennial ryegrass in soils of different organic matter contents receiving sheep excreta
期刊: Plant and Soil
作者: Pei-Tzu Kao, Heather L Buss, Steve P McGrath, Tegan Darch, Helen E Warren, Michael R F Lee
摘要: Background and aims The intake of selenium, an essential element for animals and humans, in ruminants is largely determined by selenium concentration in ingested forages, which take up selenium mainly from soil. Ruminant excreta is a common source of organic fertilizer, which provides both nutrients and organic matter. This study aims to unentangle the unclear effect of applying different types of ruminant excreta in soils of different organic matter contents on selenium uptake by forage. Methods Perennial ryegrass (Lolium perenne) was grown in soils of different organic matter contents. Urine and/or feces collected from sheep fed with organic or inorganic mineral supplements, including selenium, were applied to the soils. The selenium in the collected samples were analyzed using ICP-MS. The associated biogeochemical reactions were scrutinized by wet chemistry. Results The application of urine and/or feces resulted in either the same or lower selenium concentrations in perennial ryegrass. The excreta type did not affect total selenium accumulation in grass grown in low organic matter soil, whereas in high organic matter soil, feces resulted in significantly lower total selenium accumulation than urine, which was attributed to a possible interaction of selenium sorption in soil and microbial reduction of Se. Conclusion This one-time excreta application did not increase, but further decrease in some treatments, selenium concentration and accumulation in the perennial ryegrass. Consequently, to increase ruminant selenium intake, supplementing selenium directly to animals is more recommended than applying animal manure to soil, which might drive selenium reduction and decrease selenium uptake by grass.
47. 题目: Transformation of dissolved organic matter during UV/peracetic acid treatment
期刊: Water Research
作者: Penghui Du, Wen Liu, Qiang Zhang, Peng Zhang, Chen He, Quan Shi, Ching-Hua Huang, Junjian Wang
摘要: Peracetic acid combined ultraviolet (UV/PAA) process has garnered growing attention as a promising advanced oxidation process (AOP) for wastewater treatment, but the corresponding transformation of ubiquitous dissolved organic matter (DOM) under this AOP remains unknown. This study systematically investigated the changes in characteristics and composition of DOM under UV/PAA, as well as the underlying mechanisms by multiple spectroscopic analyses and Fourier transform ion cyclotron resonance mass spectrometry. UV/PAA treatment dramatically decreased aromaticity, apparent molecular weight, and fluorescent abundance of DOM with the production of more oxidized and saturated compounds. The reactive species (i.e., •OH and CH3C(O)O•/CH3C(O)OO•) in UV/PAA contributed primarily to DOM changes but showed different reaction selectivity and mechanisms. •OH reacts with DOM components and mainly yields oxygenation products via a radical addition pathway. Comparatively, the electron transfer route is more likely to occur in CH3C(O)O•/CH3C(O)OO•-induced DOM transformation. Aside from oxygenation products, electron transfer could exclusively generate decarboxylation products and distinguishes CH3C(O)O•/CH3C(O)OO•-based AOPs from •OH-based AOPs. These findings significantly improve knowledge of DOM alterations under UV/PAA AOP at both the bulk and molecular levels.
48. 题目: SoilFract: A mechanistic model accounting for the fate of exogenous organic matter in soil carbon and nitrogen cycles
期刊: Waste Management
作者: M. Pérémé, A. Haddon, J.-P. Steyer, J. Jimenez
摘要: As its use in agriculture grows, the fate of digestate in soil raises concerns on many different levels. In particular, the degradability of its organic matter when spread on soil is still an ongoing topic. In an effort to better understand the processes and dynamics of digestate soil incubation, C and N mineralization kinetics obtained in 358 days long laboratory incubations during decomposition of digestates were simulated using a dynamic model. The model includes twelve compartments related through processes including 18 parameters. The main novelty of this model is the use of accessibility-related variables to describe the fate of exogenous organic matter in soil, thus enabling a detailed understanding of its outcome in soil. Model calibration on cattle manure digestate incubation resulted in the estimation of parameter values. The newly calibrated model was then tested on an energy crop digestate incubation experiment. The model was able to reproduce accurately the experimental behavior of most variables.
49. 题目: Unique benthic foraminiferal communities (stained) in diverse environments of sub-Antarctic fjords, South Georgia
作者: Wojciech Majewski, Witold Szczuciński, Andrew J Gooday
摘要: . Sub-Antarctic fjords are among the environments most affected by the recent climate change. In our dynamically changing world, it is essential to monitor changes in these vulnerable settings. Here, we present a baseline study of “living” (rose-bengal-stained) benthic foraminifera from fjords of South Georgia, including fjords with and without tidewater glaciers. Their distribution is analyzed in the light of new fjord water and sediment property data, including grain size and sorting, total organic carbon, total sulfur, and δ13C of bulk organic matter. Four well-defined foraminiferal assemblages are recognized. Miliammina earlandi dominates in the most restricted, near-shore and glacier-proximal habitats, Cassidulinoides aff. parkerianus in mid-fjord areas, and Globocassidulina aff. rossensis and an assemblage dominated by Ammobaculites rostratus, Reophax subfusiformis, and Astrononion echolsi are in the outer parts of the fjords. Miliammina earlandi can tolerate strong glacial influence, including high sedimentation rates in fjord heads and sediment anoxia, as inferred from sediment color and total organic carbon / sulfur ratios. This versatile species thrives both in the food-poor inner reaches of fjords that receive mainly refractory petrogenic organic matter from glacial meltwater and in shallow-water coves, where it benefits from an abundant supply of fresh, terrestrial, and marine organic matter. A smooth-walled variant of C. aff. parkerianus, apparently endemic to South Georgia, is the calcareous rotaliid best adapted to inner-fjord conditions characterized by moderate glacial influence and sedimentation rates and showing no preference for particular sedimentary redox conditions. The outer parts of fjords with clear, well-oxygenated bottom water are inhabited by G. aff. rossensis. Ammobaculites rostratus, R. subfusiformis, and A. echolsi dominate in the deepest-water settings, with water salinities ≥ 33.9 PSU and temperatures 0.2–1.4 ∘C, characteristic of winter water and Upper Circumpolar Deep Water. The inner- and mid-fjord foraminiferal assemblages seem specific to South Georgia, although with continued warming and deglaciation, they may become more widespread in the Southern Ocean.
50. 题目: Biochar application increases maize yield under film mulching due to higher soil organic content and soil aggregate stability in a semi-arid area
期刊: Journal of Soils and Sediments
作者: Jinwen Pang, Yuhao Wang, Bingfan Wang, Jiayi Wang, Enke Liu, Fei Gao, Shikun Sun, Xiaolong Ren, Zhikuan Jia, Ting Wei, Peng Zhang
摘要: Purpose It is very important to build up soil fertility to maintain the sustainability of crop production in film mulched fields in northwest China. However, the effects of different biochar application rates on the soil organic carbon (SOC) contents and crop yields in film-mulched farmland remain unclear. The results obtained in this study can guide the selection of appropriate biochar application rates for film-mulched farmland management in semiarid areas. Methods A field experiment was conducted with four different biochar application rates (no biochar = 0 t ha–1, low = 3 t ha–1, medium = 6 t ha–1, and high = 9 t ha–1) to farmland under continuous film mulching and no-mulching in a semiarid area. The SOC contents, soil aggregate fractions, and maize yields were measured, and the soil aggregate stability was calculated. Results Mulching significantly increased the soil macro-aggregate content (15.9–83.6%) and maize yield (35.0–41.8%). Under mulching, biochar application significantly increased the mean weight diameter (MWD) and geometric mean diameter (GMD) by 10.2% and 4.5%, respectively, and the effects increased as the biochar application rate increased. In addition, applying biochar increased the SOC and aggregate organic carbon (AOC) contents, where the effects were greater under the high biochar amount than the other treatments. Biochar application also increased the contribution of SOC in macro-aggregates (> 0.25 mm) to the total SOC, thereby promoting carbon sequestration in soils. Furthermore, the yield was correlated with the biochar addition rate, and the highest yield of 12.8 t ha–1 was obtained under the highest biochar application rate. Conclusions In conclusion, biochar application significantly improved the soil aggregate characteristics and organic carbon contents of farmland under film mulching. Biochar application also helped to increase the maize yield and promote the sequestration of soil carbon.
51. 题目: Citric acid treatment directly on anaerobic digestor sludge alleviates the inhibitory effect of in-situ generated humic acids by their deconstruction and redistribution
期刊: Water Research
作者: Yanfei Tang, Jing Sun, Bin Dong, Xiaohu Dai
摘要: Humic acids were known to inhibit sewage sludge anaerobic digestion (AD) and many studies have been investigated to deal with the inhibitory effect of humic acids (HA) in raw sludge feeding the digestor. However, HA could also be in-situ produced during the sludge AD process with a significant amount, but the relieving of the inhibitory effect posed by the in-situ produced HA has been historically ignored. Thus, this study attempted to use citric acid (CA), an easily biodegradable polyatomic acid, to directly treat sludge in the anaerobic digestor instead of the feeding sludge, for alleviating inhibition caused by the in-situ produced HA. Results showed that methane production of AD batches with CA pretreatment at 0.06∼0.10 g/g TS on digestor sludge were effectively enhanced, with the highest production being 2.89 times of that observed in control AD without CA treatment and 2.08 times of that achieved by contrast AD with CA pretreatment on raw sludge. However, the AD batches with CA treatment at low dosages of 0.02∼0.04 g/g TS had lower methane production, during which sludge solubilization and hydrolysis were enhanced initially associated with released HA surfactant and hydrolytic enzymes; then later inhibited since higher structurally sound HA in SP easily rebind proteinaceous substrates and enzymes again. Whilst CA treatment at 0.06∼0.10 g/g TS could promote sludge solubilization and hydrolysis throughout the sludge AD process. This dosage-dependent effect of CA treatment can be caused by its discriminating impact on HA structure and distribution. At low dosages, complexes of HA-proteins (including hydrolases) can be decrosslinked and transferred to the soluble phase (SP), thus enhancing solubilization and hydrolysis initially. However, the released HA in SP could rebind more organics and hydrolases during AD, resulting in augmented inhibition. While the dosage increased, HA were drastically deconstructed with aromatic cores in SP migrating to extracellular polymeric substances, preventing binding effects on organics and hydrolases. Accordingly, a smart mutex-switch operational strategy of CA treatment was proposed. The results suggested, to alleviate the inhibitory effect of HA on sludge AD, more attention should be given to HA produced and accumulated in AD rather than raw sludge so that the CA treatment directly on sludge in the digestor can be a promising method.
52. 题目: Aggregation and construction mechanisms of microbial extracellular polymeric substances with the presence of different multivalent cations: Molecular dynamic simulation and experimental verification
期刊: Water Research
作者: Sainan Peng, Zhiyue Wang, Pingfeng Yu, Guiying Liao, Rui Liu, Dongsheng Wang, Weijun Zhang
摘要: Interactions between cations and extracellular polymeric substances (EPS) play an important role in the formation of microbial aggregates and have key effects on the physical properties of activated sludge across wastewater and sludge treatment process. Here, a molecular model of EPS cluster in activated sludge was constructed and simulated by molecular dynamics (MD) to probe the structural properties of EPS and interaction between EPS and prevalent multivalent cations (Ca2+, Mg2+, Al3+). Then the predicted changes in physical properties were validated against the dynamic light scattering, XAD resin fractionation and rheology test. The binding dynamics and interactions mechanisms between multivalent cations and EPS functional groups were further investigated using MD in combination with spectroscopic analysis. Results suggest that biopolymers are originally aggregated by electrostatic and intermolecular interactions forming dynamic clusters with negatively charged surface functional groups, which induced electrostatic repulsion preventing further agglomeration of biopolymer clusters. In the presence of multivalent cations, surface polar functional groups in biopolymers are connected, causing the rearrangement of EPS molecular conformation that forms larger and denser agglomerates. Reduced solvent accessible surface area, enhanced hydrophobicity, and increased binding free energy lead to a strong gel-like network of EPS. Ca2+ and Al3+ predominantly interact with functional groups in polysaccharides, promoting agglomeration of macromolecules. In contrast, Mg2+ and Al3+ disrupted the secondary structure of proteins, exposing hydrophobic interaction sites. Al3+ can better agglomerate biopolymers with its higher positive charge and shorter coordination distance as compared to Ca2+ and Mg2+, but compromised by the effect of hydration. This work offers a novel approach to explore construction and molecular aggregation of EPS, enriching the theoretical basis for optimization of wastewater and sludge treatment.
53. 题目: Study on the cadmium and copper binding characteristics of dissolved organic matter released from human-feces-biochar (HFDOM) using parallel factor analysis (PARAFAC) and two-dimensional correlation spectroscopy (2D-COS)
期刊: Environmental Science and Pollution Research
作者: Ke Chen, Yanmei Yang, Hong Zhao, Jinyuan Jiang
摘要: The benefits of applying manure directly compared to carbonized applications are controversial, and the impact of dissolved organic matter (DOM) released from human feces-based biochar (HFDOM) on the soil environment is not yet known. Comparing the properties of the HFDOM at different pyrolysis temperatures and its binding properties to heavy metals (HMs) can provide some valuable information for the application of human manure–based biochar for soil amendment or HM remediation in soils. The result of EEM-PARAFAC shows that HFDOM contains four components. A comparison of the maximum fluorescence intensity of HFDOM bound to HMs at different pyrolysis temperatures indicates that high pyrolysis temperatures reduce the amount of HFDOM. Upon comparative analysis of 2D-SFS-COS maps, cadmium (Cd(II)) preferentially binds to humic substances and fulvic-like substances at different pyrolysis temperatures (280 °C, 380 °C), respectively, while copper (Cu(II)) preferentially complexes with fulvic-like substances in both cases. The 2D-FTIR-COS graphs with different pyrolysis temperatures (280 °C, 380 °C) are observed, and Cd(II) binds preferentially to the C–H stretching (peak 3030 cm−1) of olefins, the C–O stretching vibration, and the O–H bending vibration (peak 1231 cm−1) of carboxyl groups, respectively, while Cu(II) binds predominantly to the C–O stretching of alcohols, ethers, and esters (peak 1084 cm−1), the C = O stretch of the carboxylic acid (peak 1590 cm−1), respectively. The variability of these findings suggests that the pyrolysis temperature exerts a significant influence on the functional groups in HFDOM. Furthermore, the complexation stability constant between Cu(II) and the components decreases as the pyrolysis temperature increases, probably because the pyrolysis temperature changes the content of HFDOM and the distribution of functional groups, but the assessment of the influence still needs to be further investigated.
54. 题目: Root distribution, soil water depletion, and water productivity of sweet corn under deficit irrigation and biochar application
期刊: Agricultural Water Management
作者: Manpreet Singh, Sukhbir Singh, Sanjit Deb, Glen Ritchie
摘要: Root modifications can play a vital role in crop adjustments to soil water deficit. It is important to understand root growth and soil water depletion patterns to develop effective cropping systems, especially in semi-arid regions like Texas High Plains (THP). This study evaluated root growth, soil water depletion, and water productivity (WP) of sweet corn under three deficit irrigation treatments [100 %, 70 % and 40 % crop evapotranspiration (ETc)] and biochar application (hardwood and softwood). The experimental units were replicated 4 times in a split-plot design. The results revealed no interaction between irrigation and biochar treatments for almost all measured parameters. The 70 % ETc treatment increased the root length density (RLD) over 100 % ETc during 2019, while no differences were observed among irrigation treatments in 2020. Both deficit irrigations (70 % and 40 % ETc) increased soil water depletion compared to 100 % ETc, the highest being in 40 % ETc. The 70 % ETc maintained a similar yield and increased WP by 21 % compared to 100 % ETc across two years. However, 40 % ETc resulted in significant decline in yield and WP in 2020. The hardwood biochar increased RLD over no biochar treatment without affecting the soil water status and WP. Long-term studies are needed to investigate biochar effects beyond two years of application. In case of limited water availability, 70 % ETc can be recommended as an alternative to 100 % ETc in the THP of the US.
55. 题目: Description of Dissolved Organic Matter Transformational Networks at the Molecular Level
期刊: Environmental Science & Technology
作者: Dennys Leyva, Muhammad Usman Tariq, Rudolf Jaffé, Fahad Saeed, Francisco Fernandez-Lima
摘要: Dissolved Organic Matter (DOM) is an important component of the global carbon cycle. Unscrambling the structural footprint of DOM is key to understand its biogeochemical transformations at the mechanistic level. Although numerous studies have improved our knowledge of DOM chemical makeup, its three-dimensional picture remains largely unrevealed. In this work, we compare four solid phase extracted (SPE) DOM samples from three different freshwater ecosystems using high resolution mobility and ultrahigh-resolution Fourier transform ion cyclotron resonance tandem mass spectrometry (FT-ICR MS/MS). Structural families were identified based on neutral losses at the level of nominal mass using continuous accumulation of selected ions-collision induced dissociation (CASI-CID)FT-ICR MS/MS. Comparison of the structural families indicated dissimilarities in the structural footprint of this sample set. The structural family representation using Cytoscape software revealed characteristic clustering patterns among the DOM samples, thus confirming clear differences at the structural level (Only 10% is common across the four samples.). The analysis at the level of neutral loss-based functionalities suggests that hydration and carboxylation are ubiquitous transformational processes across the three ecosystems. In contrast, transformation mechanisms involving methoxy moieties may be constrained in estuarine systems due to extensive upstream lignin biodegradation. The inclusion of the isomeric content (mobility measurements at the level of chemical formula) in the structural family description suggests that additional transformation pathways and/or source variations are possible and account for the dissimilarities observed. While the structural character of more and diverse types of DOM samples needs to be assessed and added to this database, the results presented here demonstrate that Graph-DOM is a powerful tool capable of providing novel information on the DOM chemical footprint, based on structural interconnections of precursor molecules generated by fragmentation pathways and collisional cross sections.
56. 题目: Physical impact mechanism of large macroaggregate fragmentation on short‐term soil microbial respiration after rainfall
期刊: European Journal of Soil Science
作者: Yue Feng, Jianzhang Xiao, Yingqi Wei, Hong Cai, Jinghua Yu
摘要: The uncertainty of soil respiration under the influence of rainfall significantly affects the carbon flux in forest ecosystems. Thus, this study assessed the impact mechanism of aggregate changes on short-term forest soil microbial respiration under rainfall simulation. The response of short-term soil microbial respiration to the variation in aggregate distribution, carbon concentration in the aggregate particles, dissolved organic carbon (DOC), dry bulk density, volumetric water content, capillary porosity and soil aeration in the forest soil was investigated by a self-developed rainfall simulation system under 50 and 80 mm/h rainfall treatments. The system ensured the controllability, continuity and integrity of the analysis from soil erosion to soil respiration. A proportional decrease in large macroaggregates (> 2 mm) and an increase in small macroaggregates (0.25-2 mm) were detected due to rainfall, leading to the release of coarse particulate organic matter in large macroaggregates and an enrichment in microaggregates within small macroaggregates. The splitting of macroaggregates increased the DOC content and decreased the porosity and aeration of the soil. The CO2 flux decreased immediately after rainfall treatment, and it increased at 12 h after the end of 80 mm/h rainfall. Moreover, the soil immediately emitted CH4 at the end of 80 mm/h rainfall. Large macroaggregates and DOC had positive conditional effect on respective CO2 and CH4 fluxes at the end of rainfall. The results indicate that short-term soil microbial aerobic respiration is mainly regulated by the remaining macroaggregate distribution immediately after rainfall. Moreover, short-term soil microbial anaerobic respiration is mainly mediated by the DOC and microaggregates released from large macroaggregates under soil water saturation. The study concludes that the uncertainty of short-term soil microbial respiration is mainly derived from the random fragmentation and redistribution of macroaggregates in the soil immediately after rainfall treatments.
57. 题目: Variations in dissolved organic matter chemistry on a vertical scale in the eastern Indian Ocean
期刊: Water Research
作者: Yang Liu, Xiaofang Liu, Yi Long, Yujian Wen, Chao Ma, Jun Sun
摘要: Oceans cover approximately 71% of the Earth's surface area, which is why some people refer to the Earth as a large water sphere. Marine dissolved organic matter (DOM) constitutes the main carbon pool for biogeochemical cycles and plays an important role in global carbon dynamics. Here, the molecular composition and component characteristics of surface (5 m), deep chlorophyll maximum (DCM), and deep (2000 m) layer DOM in the eastern Indian Ocean (EIO) were investigated using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and three-dimensional fluorescence spectroscopy. Thousands of individual DOM formulas (approximately 3716-6986 formulas) were detected at 100-700 Da, showing a Gaussian distribution. The elements carbon (C), hydrogen (H), oxygen (O), nitrogen (N) and sulfur (S) were detected and constituted four formula classes in solid-phase extracted marine DOM samples. Furthermore, the order of the percent intensity of the formulas was CHO > CHNO > CHOS > CHNOS. Carboxylic-rich alicyclic molecule (CRAM) compounds, as part of recalcitrant DOM (RDOM), were detected at 61.32%-78.77% (by intensity). In addition, the concept of islands of stability (IOS, approximately 3.99%-11.22%) has been proposed in this study, representing the most stable components in the marine environment. Such molecular formulas as described above probably contribute to increased RDOM content in the EIO and potentially reflect enhanced accumulation or sequestration of RDOM in the deep layer. The variation in the spectroscopic indices (FI, β/α, BIX, and HIX) and fluorescent components (C1 to C4) with depth indicates a shift from protein-like to humic-like components, leading to gradual aging of the water column. In brief, this study relies on data from marine DOM in the EIO to provide a molecular and chemical background for global models of marine DOM production, transformation and sequestration.
58. 题目: Effects of fire on the soil microbial metabolic quotient: A global meta-analysis
作者: Weichao Liu, Zhenjiao Zhang, Jiaxin Li, Yuhao Wen, Fuhe Liu, Wei Zhang, Hanyu Liu, Chengjie Ren, Xinhui Han
摘要: Soil microorganisms play an essential role in the biogeochemical cycles; however, the response of soil microorganisms to fire is largely unknown. Understanding this response has become increasingly important in the current context of global ecosystem disturbance, which is characterized by an increased frequency of fires. Therefore, a global meta-analysis of 371 cases from 81 published studies was conducted to explore the comprehensive effects of fires on soil microbial properties. The results show that fires significantly increased microbial metabolic quotient (qCO2), by 19.45% on average, and decreased soil microbial biomass carbon (MBC) by 8.41% and fungal biomass by 27.17%. Moreover, the response of these microbial indices to fires intensified with increasing fire intensity. In addition, ecosystem types and climate zones have an impact on the response of MBC and qCO2 to fires. Among them, MBC and qCO2 in coniferous forests and continental climate zones are the most sensitive to fires. A correlation analysis displayed that the response of soil organic carbon (SOC) to fires was significantly and positively correlated with the response of MBC but negatively correlated with the response of qCO2. Furthermore, fires reduced SOC in the short term, but had no significant impact in the long term. Collectively, this study emphasizes the need to pay greater attention to forest fire protection in arid areas under global climate change.
59. 题目: Evaluating the potential of hydrochar as a soil amendment
期刊: Waste Management
作者: Daniela Bona, Daniela Bertoldi, Gigliola Borgonovo, Stefania Mazzini, Stefano Ravasi, Silvia Silvestri, Claudio Zaccone, Beatrice Giannetta, Fulvia Tambone
摘要: In this study, hydrochar (HC), a carbon-rich product originated from hydrothermal conversion treatment (HTC), was obtained from wastes of the wine and dairy industries. The effect of mixing secondary char and compost was tested, before and after the aerobic mixing of compost (COM) and HC at increasing doses (from 15 to 75 Mg ha−1 DM), in an effort to lower the HC phytotoxicity due to potential phytotoxic compounds of secondary char. The results indicated that, after the aerobic stabilization, the mix HC/COM was able to double the plant growth in comparison to COM alone. The presence of easily degradable organic compounds probably led to poor stability of HC, increased microbial activity and, consequently, root anoxia when used at high doses. Chemical, spectroscopic and thermal investigation confirmed this hypothesis. In particular, HC shows a high content of dissolved organic matter, characterized by the presence of small molecules, which is negatively correlated with the growth index of lettuce. Furthermore, thermal characterization suggests a higher proportion of less complex and thermally stable molecular compounds in HC in comparison to COM. Therefore, co-composting of HC allows obtaining a useful amendment to support soil organic matter and fertility.
60. 题目: Insight into the Effect of Natural Organic Matter on the Photooxidation of Arsenite Induced by Colloidal Ferric Hydroxides in Water
期刊: Water Research
作者: Yi Wu, Xingyun Huang, Jing Xu, Wenyu Huang, Jinjun Li, Gilles Mailhot, Feng Wu
摘要: Surface complexation of arsenite (As(III)) on colloidal ferric hydroxide (CFH) plays an important role not only in the adsorptive immobilization of As(III) but also in the subsequent oxidation of As(III) to arsenate (As(V)) through light-induced ligand-to-metal charge transfer (LMCT) in water at near-neutral pH. However, the effects of natural organic matter (NOM), especially humic substances (HSs) and low molecular weight carboxylic acids (CAs), on the photochemistry of the CFH-As(III) system have not been sufficiently understood. In this work, the inhibition of photooxidation of As(III) in terms of the observed apparent rate constant (kobs) by six HSs (below 16 mg L−1) and seven CAs (below 2.5 mm) has been observed in water containing 66 μm Fe(III) and 5 μm As(III) at pH 7 under simulated solar irradiation consisting of UVA (λmax 365 nm) and UVB (λmax 313 nm) lights. Total inhibition factors (T) have been determined from the combined effect of light-screening factor (S) and competitive complexation factor (C), wherein both S and C varied with NOM concentration. S was obtained by determining the absorbance of NOM, and C was obtained by fitting modified Langmuir or Freundlich models to the amount of As(III) desorbed from CFH upon the addition of NOM. Statistical analysis between the experimental Texp and the calculated one according to Tcal = S × C showed that the Freundlich model (RMSE for HS 0.1609 and for CA 0.1771) was better than the Langmuir model and was statistically robust (QLOO2= 0.691 > 0.5). This work provided an estimation method for the effects of NOM on As(III) photooxidation in the presence of CFH as well as a deeper understanding of the transformation of arsenic species in sunlit water.