21. 题目: Deciphering metabolic alterations in algae cultivated in spent media as means for enhancing algal biorefinery sustainability
期刊: Bioresource Technology
作者: Enlin Lo, Neha Arora, George P. Philippidis
摘要: The recycling of unfiltered spent media during cultivation of Chlorella vulgaris was studied using metabolomics in an effort to enhance water and nutrient sustainability and reduce operating costs in algal biorefineries. Cultivation in spent media resulted in reduced biomass and lipid productivity by 14% and 19%, respectively, compared to fresh media. The decrease was related to a detected lower nutrient uptake. Nevertheless, carbohydrate content (28% of dry cell weight) and α-linolenic acid content (27 % of fatty acids) were higher in spent media cultures than in fresh media. Metabolomics analysis of intracellular metabolites revealed downregulation of nitrogen assimilation, tricarboxylic acid cycle, structural lipids, and energy metabolism, but upregulation of stress mitigation and carbohydrate synthesis. No growth was supported by spent media during a second cultivation cycle and was likely due to the identified extracellular accumulation of humic acid and free fatty acids that acted as growth auto-inhibitors.
22. 题目: Emerging forest–peatland bistability and resilience of European peatland carbon stores
期刊: Proceedings of the National Academy of Sciences
作者: Ype van der Velde, Arnaud J. A. M. Temme, Jelmer J. Nijp, Maarten C. Braakhekke, George A. K. van Voorn, Stefan C. Dekker, A. Johannes Dolman, Jakob Wallinga, Kevin J. Devito, Nicholas Kettridge, Carl A. Mendoza, Lammert Kooistra, Merel B. Soons, Adriaan J. Teuling
摘要: Northern peatlands store large amounts of carbon. Observations indicate that forests and peatlands in northern biomes can be alternative stable states for a range of landscape settings. Climatic and hydrological changes may reduce the resilience of peatlands and forests, induce persistent shifts between these states, and release the carbon stored in peatlands. Here, we present a dynamic simulation model constrained and validated by a wide set of observations to quantify how feedbacks in water and carbon cycling control resilience of both peatlands and forests in northern landscapes. Our results show that 34% of Europe (area) has a climate that can currently sustain existing rainwater-fed peatlands (raised bogs). However, raised bog initiation and restoration by water conservation measures after the original peat soil has disappeared is only possible in 10% of Europe where the climate allows raised bogs to initiate and outcompete forests. Moreover, in another 10% of Europe, existing raised bogs (concerning ∼20% of the European raised bogs) are already affected by ongoing climate change. Here, forests may overgrow peatlands, which could potentially release in the order of 4% (∼24 Pg carbon) of the European soil organic carbon pool. Our study demonstrates quantitatively that preserving and restoring peatlands requires looking beyond peatland-specific processes and taking into account wider landscape-scale feedbacks with forest ecosystems.
23. 题目: Effect of pyrolysis conditions on environmentally persistent free radicals (EPFRs) in biochar from co-pyrolysis of urea and cellulose
期刊: Science of The Total Environment
作者: Dongmei Bi, Fupeng Huang, Mei Jiang, Zhisen He, Xiaona Lin
摘要: Biochar derived from nitrogen-rich pyrolysis of biomass can be used as a soil conditioner, but it contains a large amount of environmental persistent free radicals (EPFRs). EPFRs are a newly identified environmentally harmful substance, and the detection and research on EPFRs in nitrogen-rich pyrolyzed char is lacking. Biochars prepared from cellulose-urea mixtures at different temperatures, residence times, and urea ratios were analyzed in this study. EPFRs in biochar prepared at 500 °C had the highest spin concentrations. Substituted aromatic compounds were the precursors to the EPFRs. The types of EPFRs in biochars shifted from oxygen-centered at 400 °C to carbon- and oxygen-centered in the 450–600 °C range due to a reduction in oxygen-containing functional groups. Residence time experiments showed that most EPFRs formed in the first 5 min of pyrolysis. C was the main element used for the formation of EPFRs, while N content was negatively correlated with the concentration of EPFRs. Pyrolysis temperature was the key factor determining the types of EPFRs produced, while proportion of urea only affected the concentrations of EPFRs and not type. The results of this study are of great significance for understanding the environmental behavior of common EPFRs in nitrogen-rich biochar.
24. 题目: Photochemical Behavior of Microbial Extracellular Polymeric Substances in the Aquatic Environment
期刊: Environmental Science & Technology
作者: Shaofeng Zhou, Zhiyang Liao, Beiping Zhang, Rui Hou, Yi Wang, Shungui Zhou, Yifeng Zhang, Zhiyong Jason Ren, Yong Yuan
摘要: Microbially derived extracellular polymeric substances (EPSs) occupy a large portion of dissolved organic matter (DOM) in surface waters, but the understanding of the photochemical behaviors of EPS is still very limited. In this study, the photochemical characteristics of EPS from different microbial sources (Shewanella oneidensis, Escherichia coli, and sewage sludge flocs) were investigated in terms of the production of reactive species (RS), such as triplet intermediates (3EPS*), hydroxyl radicals (•OH), and singlet oxygen (1O2). The steady-state concentrations of •OH, 3EPS*, and 1O2 varied in the ranges of 2.55–8.73 × 10–17, 3.01–4.56 × 10–15, and 2.08–2.66 × 10–13 M, respectively, which were within the range reported for DOM from other sources. The steady-state concentrations of RS varied among different EPS isolates due to the diversity of their composition. A strong photochemical degradation of the protein-like components in EPS isolates was identified by excitation emission matrix fluorescence with parallel factor analysis, but relatively, humic-like components remained stable. Fourier-transform ion cyclotron resonance mass spectrometry further revealed that the aliphatic portion of EPS was resistant to irradiation, while other portions with lower H/C ratios and higher O/C ratios were more susceptible to photolysis, leading to the phototransformation of EPS to higher saturation and lower aromaticity. With the phototransformation of EPS, the RS derived from EPS could effectively promote the degradation of antibiotic tetracycline. The findings of this study provide new insights into the photoinduced self-evolution of EPS and the interrelated photochemical fate of contaminants in the aquatic environment.
25. 题目: Accessing biochar's porosity using a new low field NMR approach and its impacts on the retention of highly mobile herbicides
作者: Letícia de Pierri, Etelvino Henrique Novotny, Carlos Eduardo Pellegrino Cerri, Adijailton José de Souza, Bianca Braz Mattos, Valdemar Luiz Tornisielo, Jussara Borges Regitano
摘要: Agrowaste biochars [sugarcane straw (SS), rice husk (RH), poultry manure (PM), and sawdust (SW)] were synthesized at different pyrolysis temperatures (350, 450, 550, and 650 °C) to evaluate their potential to retain highly mobile herbicides, such as hexazinone and tebuthiuron that often contaminate water resources around sugarcane plantations. A new low field nuclear magnetic resonance approach based on diffusion in internal magnetic field decay (NMR-DDIF) was successfully used to determine biochar's porosity and specific surface area (SSA) to clear the findings of this work. SSA of pores with diameters >5.0 μm increased with pyrolysis temperatures and seemed to dictate biochar's retention, which was >70% of the applied amounts at 650 °C. These macropores appear to act as main arteries for herbicide intra-particle diffusion into smaller pores, thus enhancing herbicides retention. Biochar granulometry had little, but herbicide aging had a significant effect on sorption, mainly of tebuthiuron. However, soils amended with 10,000 kg ha−1 of the biochars showed low sorption potential. Therefore, higher than usual biochar rates or proper incorporation strategies, i.e., surface incorporation, will be needed to remediate areas contaminated with these highly mobile herbicides, thus precluding their leaching to groundwaters.
26. 题目: Influence of pH, depth and humic acid on metal and metalloids recovery from municipal solid waste landfills
期刊: Science of The Total Environment
作者: H. Lee, F. Coulon, S.T. Wagland
摘要: The recovery of metal(loid)s from municipal solid waste (MSW) samples <10 years old and >10 years old was investigated using a series of pH-dependence leaching batch tests ranging between pH 2 and 10. Further to this, the influences of various parameters, including depth, and humic acid (HA) concentrations on the recovery of metal(loid)s including Li, Al, Cr, Mn, Co, Ni, Cu, Zn, As, Cd, Pb, and Hg were investigated. The Visual MINTEQ geochemical software was then used to model the metal(loid)s release in the presence of different HA concentrations ranging from 28 mg/L to 100 mg/L, which can be found in landfill sites and pH ranging from 2 to 10. The results showed that the release amount of Li, Al, Cr, Mn, Co, Ni, Cu, Zn, As, Cd, Pb, and Hg are in the range of 0.03–0.14 mg/L, 0.65–83.33 mg/L, 0.01–0.19 mg/L, 0.18–18.17 mg/L, 0.01–0.09 mg/L, 0.06–0.38 mg/L, 0.12–5.2 mg/L, 0.14–11.57 mg/L, 0.02–0.10 mg/L, 0.00–26.17 mg/L, 0.03–25.17 mg/L, and 0.00–0.01 mg/L with deionised water as leachant at different pH. The release amount of HA was relatively increased from 0 to 2% in 48–55 m compared to 3–9 m in the MSW landfill. HA can promote the leaching rate of metals with an appropriate amount. Base on the study results, the optimal condition of leaching metals was pH 2, and HA 28 mg/L at less than 10 m depth. The high concentration of metals in landfill leachate may be enhanced to effectively recover metals as the critical challenge of recovering metals from leachate is the low concentration of metals. Thus, the information can be useful for economically feasible in the recovery of metals.
27. 题目: Chemistry and Isotope Fractionation of Divalent Mercury during Aqueous Reduction Mediated by Selected Oxygenated Organic Ligands
期刊: Environmental Science & Technology
作者: Huifang Zhao, Bo Meng, Guangyi Sun, Che-Jen Lin, Xinbin Feng, Jonas Sommar
摘要: We have investigated the chemistry and Hg isotope fractionation during the aqueous reduction of HgII by oxalic acid, p-quinone, quinol, and anthraquinone-2,6-disulfonate (AQDS), a derivate of anthraquinone (AQ) that is found in secondary organic aerosols (SOA) and building blocks of natural organic matter (NOM). Each reaction was examined for the effects of light, pH, and dissolved O2. Using an excess of ligand, UVB photolysis of HgII was seen to follow pseudo-first-order kinetics, with the highest rate of ∼10–3 s–1 observed for AQDS and oxalic acid. Mass-dependent fractionation (MDF) occurs by the normal kinetic isotope effect (KIE). Only the oxalate ion, rather than oxalic acid, is photoreactive when present in HgC2O4, which decomposes via two separate pathways distinguishable by isotope anomalies. Upon UVB photolysis, only the reduction mediated by AQDS results in a large odd number mass-independent fractionation (odd-MIF) signified by enrichment of odd isotopes in the reactant. Consistent with the rate, MDF, and odd-MIF reported for fulvic acid, our AQDS result confirms previous assumptions that quinones control HgII reduction in NOM-rich waters. Given the magnitude of odd-MIF triggered via a radical pair mechanism and the significant rate in the presence of air, reduction of HgII by photoproducts of AQDS may help explain the positive odd-MIF observed in ambient aerosols depleted of HgII.
28. 题目: Reduction of cytotoxicity and DNA double-strand break effects of wastewater by ferrate(VI): Roles of oxidation and coagulation
期刊: Water Research
作者: Qian-Yuan Wu, Xue-Si Lu, Ming-Bao Feng, Wen-Long Wang, Ye Du, Lu-Lin Yang, Hong-Ying Hu
摘要: Ferrate(VI) (Fe(VI)) can oxidize individual pollutants, but the pollutant oxidation does not necessarily result in toxicity reduction. Besides, Fe(VI) resultant Fe(III) particles has previously been used to remove heavy metals, but its influence on organic matter and toxicity of wastewater is unknown. This study investigated influence of Fe(VI) on the cytotoxicity and DNA double-strand break (DSB) effects of secondary effluents from wastewater treatment plants to Chinese hamster ovary cells. Adding 5.0 mg/L Fe(VI) as Fe reduced the cytotoxicity and genotoxicity of secondary effluents by 44%–71% and 40%–59%, respectively. The toxicity reduction could be explained by the alleviation of oxidative stress in cells when they were exposed to the Fe(VI)-treated organic matter. Oxidation and coagulation accounted for 60% and 40% of the reductions in cytotoxicity and genotoxicity, demonstrating that both oxidation and coagulation processes can play important roles in reducing toxicity. Molecular weight (MW)-distribution analysis showed that the oxidation process was favored for removing ultraviolet absorbance and fluorescence intensity of organic matter, while the coagulation process removed more dissolved organic carbon (DOC), especially the DOC of fractions with MW <500 Da. Compared with ferric chloride, the Fe(VI) resultant Fe(III) showed better coagulation performance on organic matter, cytotoxicity and genotoxicity removal, because of the different particle sizes and crystalline structures. This study highlights the benefit of using Fe(VI) in advanced treatment as Fe(VI) reduced the overall toxicity of secondary effluents.
29. 题目: Remote sensing estimation of the concentration and sources of coloured dissolved organic matter based on MODIS: A case study of Erhai lake
期刊: Ecological Indicators
作者: Hao Zhang, Bo Yao, Shengrui Wang, Guoqiang Wang
摘要: The use of satellite remote sensing to estimate coloured dissolved organic matter (CDOM) and identify its potential sources is important for monitoring lake water quality and implementing management strategies. In this study, taking Erhai Lake as an example and based on MODIS/Aqua satellite images and in-situ measured data, we used empirical and semi-empirical methods to develop algorithms for CDOM and the fluorescence index (FI370) from remote sensing reflectance (Rrs(λ)). The temporal and spatial distributions of the CDOM concentration and FI370 in Erhai Lake during 2013–2019 were retrieved. The results show the following. (1) The band ratio (Rrs(469)+Rrs(645))/Rrs(555) model could estimate the CDOM absorption coefficient at 412 nm (aCDOM(412)) (R2=0.507), and it was relatively stable. Using the band ratio Rrs(645)/Rrs(469) combined with the chlorophyll-a (Chl-a) APProach by ELimination (APPEL) model, a semi-empirical inversion model of FI370 performed with satisfactory accuracy (R2=0.550) and was more accurate than the empirical algorithm (R2=0.505). (2) During the period of 2013–2019, the CDOM concentration in Erhai Lake generally decreased from the northern to the central to the southern parts of the lake, and the CDOM concentration was higher in summer and autumn than in spring and winter. FI370 was higher in the northern and western coastal waters and lower in the central, southern and eastern parts of the lake. FI370 in autumn and winter was higher than that in spring and summer. CDOM was affected by both terrestrial and internal sources, and their relative contributions were not the same in different seasons. (3) For different Chl-a concentrations, different CDOM concentration models had better retrieval effects, i.e., Rrs(645))/Rrs(555) and (Rrs(469)+Rrs(645))/Rrs(555) had the best performance when Chl-a<10 μg/L and Chl-a>10 μg/L, respectively. The inversion models established in this study offer improved quantifications of the CDOM concentration and the FI370 in Erhai Lake, providing important support for monitoring water quality and implementing efficient management strategies.
30. 题目: The bioavailability of nitrogen associated with sediment in riverine plumes of the Great Barrier Reef
期刊: Marine Pollution Bulletin
作者: Alexandra Garzon-Garcia, Joanne M. Burton, Stephen Lewis, Zoe Bainbridge, Rob De Hayr, Philip Moody, Jon Brodie
摘要: This study quantified the bioavailable nitrogen contribution from riverine plumes to Great Barrier Reef (GBR) coastal environments. The potential bioavailable nitrogen from two Dry Tropics riverine plumes was considerable [9 - 30% added to the end-of-catchment dissolved inorganic nitrogen (DIN) load]. Particulate inorganic nitrogen conversion to DIN was an important process in short timeframes (25% to 100% of the generated load). The remaining load was contributed by microbial mineralisation of organic nitrogen. Flood plume sediment has potential to generate nitrogen once deposited and/or resuspended. Nitrogen generation was insignificant in a few plumes where immobilisation of nitrogen in bacteria biomass occurred. The source of organic matter in the plumes and availability of nitrogen relative to organic matter were important determinants of mineralisation/immobilisation. This research demonstrates that riverine plumes have potential to be considerable sources of bioavailable nitrogen to coastal environments of the GBR and that organic matter is a key bioavailability driver.
31. 题目: Variations in soil aggregation, microbial community structure and soil organic matter cycling associated to long-term afforestation and woody encroachment in a Mediterranean alpine ecotone
作者: Carlos Ortiz, María José Fernández-Alonso, Barbara Kitzler, Eugenio Díaz-Pinés, Gustavo Saiz, Agustín Rubio, Marta Benito
摘要: Afforestation and subsequent expansion of trees on former grasslands may significantly impact the structure and activity of the soil microbial community, altering soil aggregation and affect its potential to store and cycle organic matter (OM). We investigated OM dynamics in aggregate-size topsoil samples collected along a Mediterranean alpine ecotone consisting of three vegetation types (grassland/shrubland, mixed shrubland-pine, and pine forest) in central Spain. Analytical determinations of soil organic carbon (SOC), total nitrogen (TN), particulate OM (POM), mineral-associated OM (MaOM), and the stable isotopic composition of carbon were conducted in each of the four aggregate-size fractions considered. Additionally, the structure of the microbial community (assessed as PLFA abundance), and the β-glucosidase and β-glucosaminidase activities were determined in bulk soil samples. More than half of the soil mass was contained within small macroaggregates regardless of vegetation type. SOC and TN values increased with decreasing aggregate-size classes across all vegetation types. The stability of microaggregates was negatively affected by the expansion of woody vegetation, which resulted in tree-dominated stands showing comparatively lower SOC and TN values in the smaller aggregate-size classes. On the other hand, these vegetation dynamics promoted soil macro-aggregation. While SOC contents did not show significant differences between land covers, vegetation shifts induced changes in the soil microbial community. Soil δ13C values, the abundance of gram-positive bacteria and β-glucosidase activity were significantly higher in grasslands/shrublands than in forests, while significantly higher fungi/bacteria ratio was observed in forests. Small macroaggregates appear to play a key role in the stabilisation of relatively unprocessed OM across all vegetation types, as suggested by their significantly higher concentrations of POM. However, this fraction represents the most labile pool of OM, and as such, it is the most exposed to mineralisation. We conclude that the afforestation and potential vegetation shifts experienced in Mediterranean alpine grasslands lead to distinct changes in soil microbial communities, aggregation and soil OM dynamics, which given the strong temperature sensitivity to decomposition commonly reported in cold environments, suggests that soil OM in these high-elevation ecosystems may become highly vulnerable to environmental change.
32. 题目: Biochar derived from fruit by-products using pyrolysis process for the elimination of Pb(II) ion: An updated review
作者: Farihahusnah Hussin, Mohamed Kheireddine Aroua, Małgorzata Szlachta
摘要: Water pollution is one of the most concerning global environmental problems in this century with the severity and complexity of the issue increases every day. One of the major contributors to water pollution is the discharge of harmful heavy metal wastes into the rivers and water bodies. Without proper treatment, the release of these harmful inorganic waste would endanger the environment by contaminating the food chains of living organisms, hence, leading to potential health risks to humans. The adsorption method has become one of the cost-effective alternative treatments to eliminate heavy metal ions. Since the type of adsorbent material is the most vital factor that determines the effectiveness of the adsorption, continuous efforts have been made in search of cheap adsorbents derived from a variety of waste materials. Fruit waste can be transformed into valuable products, such as biochar, as they are composed of many functional groups, including carboxylic groups and lignin, which is effective in metal binding. The main objective of this study was to review the potential of various types of fruit wastes as an alternative adsorbent for Pb(II) removal. Following a brief overview of the properties and effects of Pb(II), this study discussed the equilibrium isotherms and adsorption kinetic by various adsorption models. The possible adsorption mechanisms and regeneration study for Pb(II) removal were also elaborated in detail to provide a clear understanding of biochar produced using the pyrolysis technique. The future prospects of fruit waste as an adsorbent for the removal of Pb(II) was also highlighted.
33. 题目: Biochar from constructed wetland biomass waste: A review of its potential and challenges
作者: Xiaoqiang Cui, Jiangtao Wang, Xutong Wang, Muhammad Bilal Khan, Min Lu, Kiran Yasmin Khan, Yingjin Song, Zhenli He, Xiaoe Yang, Beibei Yan, Guanyi Chen
摘要: Constructed wetland is considered a promising approach for water remediation due to its high efficiency, low operation costs, and ecological benefits, but the large amounts of wetland plant biomass need to be properly harvested and utilized. Recently, wetland plant derived biochar has drawn extensive attention owing to its application potential. This paper provides an updated review on the production and characteristics of wetland plant derived biochar, and its utilization in soil improvement, carbon sequestration, environmental remediation, and energy production. In comparison to hydrothermal carbonization and gasification, pyrolysis is a more common technique to convert wetland plant to biochar. Characteristics of wetland plant biochars varied with plant species, growth environment of plant, and preparation conditions. Wetland plant biochar could be a qualified soil amendment owing to its abundant nutrients. Notably, wetland plant biochar exhibited considerable sorption capacity for various inorganic and organic contaminants. However, the potentially toxic substances (e.g. heavy metal and polycyclic aromatic hydrocarbons) retained in wetland plant biochar should be noticed before large-scale application. To overcome the drawbacks from the scattered distribution, limited productivity, and seasonal operation of constructed wetlands, the economic feasibility of wetland plant biochar production system could be improved via using mobile pyrolysis unit, utilizing local waste heat, and exploiting all the byproducts. Future challenges in the production and application of wetland plant derived biochar include the continuous supply of feedstock and proper handling of potentially hazardous components in the biochar.
34. 题目: Pore characteristics of hydrochars and their role as a vector for soil bacteria: A critical review of engineering options
期刊: Critical Reviews in Environmental Science and Technology
作者: Philipp Thunshirn, Walter W. Wenzel, Christoph Pfeifer
摘要: Hydrothermal carbonization (HTC) is the method of choice to convert wet waste biomass to hydrochars. Their porous structure can serve as a microenvironment to plant-growth-promoting rhizobacteria (PGPR), supporting their growth, survival, and activities. As published work lacks the systematic compilation of pore characteristics of hydrochars related to bacterial colonization, we collect available data and elaborate on their dependence on the carbonization process conditions, feedstocks, and methodology of pore system characterization. Our analysis indicates a high abundance of pores sized between 1 and 20 μm relevant for the protection of PGPR from predators, and of nutrients and labile C in hydrochars supporting bacterial growth. In addition to the selection of optimized process parameters and feedstocks (240–260 °C, low feedstock pH, non-lignocellulosic biomass), adding mineral amendments prior to HTC offers opportunities for engineering hydrochars with an even larger share of pore space suited for bacterial colonization. Using the comprehensive literature on biochars, we demonstrate that the interior pore space in chars determines the potential to serve as an inoculum carrier to PGPR, thereby enhancing nutrient acquisition and protecting plants from diseases and abiotic stresses. The pore characteristics of hydrochars are comparable to biochars, and hydrochars are generally superior in providing a labile C reservoir that PGPR can readily access. We argue that HTC provides a cost-effective conversion route to produce PGPR vectors/carriers from wet (waste) biomass serving various environmental management objectives (waste recycling, soil fertility, soil remediation technologies) and circular bioeconomy (sustainable agriculture, substituting non-renewable carrier materials and fertilizers). Highlights We review the role of pore characteristics of hydrochars for bacterial colonization We identify opportunities for engineering hydrochars to provide favorable habitat conditions to PGPR 240–260 °C, low pH, non-lignocellulosic feedstocks, and adding mineral amendments increase the habitable pore space Hydrochars offer suitable pore characteristics and high labile C amounts and are promising PGPR carriers/vectors
35. 题目: Accelerated humification and alteration of microbial communities by distillers' grains addition during rice straw composting
期刊: Bioresource Technology
作者: Liheng Ren, Binghua Yan, Mukesh Kumar Awasthi, Jiachao Zhang, Hongli Huang, Lihua Zhang, Lin Luo
摘要: This research explored the influence of distillers' grains amendment on the humification performance and microbial communities during rice straw composting. The composition of dissolved organic matter and maturity index were analyzed by the fluorescence excitation emission matrix spectroscopy and parallel factor analysis. High-throughput sequencing and redundancy analysis were employed for revealing the structure dynamics for microbial community and their shaping factors, respectively. Results indicated that addition of distillers' grains effectively increased the microbial activity, which was beneficial to the organic matter degradation and nitrogen conservation. Microbial community structures were significantly changed with different amendment strategies. Nitrate, water soluble carbon, organic matter, ammonium were the key parameters influencing the variation of bacterial community in different treatments. Water soluble carbon significantly affected the dominant fungal community dynamics. These results showed that addition of distillers' grains effectively improved the nutritional status and changed the microbial communities during rice straw composting.
36. 题目: Full Inversion Tillage (FIT) during pasture renewal as a potential management strategy for enhanced carbon sequestration and storage in Irish grassland soils
期刊: Science of The Total Environment
作者: Andrew P. Madigan, Jesko Zimmermann, Dominika J. Krol, Michael Williams, Michael B. Jones
摘要: It has been suggested that the sequestration of CO2 by agricultural soils offers a means to reduce atmospheric greenhouse gas (GHG) concentrations and in turn mitigate the impacts of climate change. Carbon sequestration by grassland soils, which account for more than 60% of agricultural land use in Ireland, could contribute to a successful net reduction of atmospheric GHG emissions in accordance with the COP21 Paris Agreement. However, current estimates of soil carbon sequestration are variable and it is likely that many permanent grasslands are close to saturation. A literature search shows that soil carbon sequestration is enhanced by a variety of different management strategies, although one option that has only been examined to date in New Zealand is full inversion tillage (FIT) during grassland renovation. FIT involves inverting topsoil, generally to depths of 30 cm, resulting in the movement of C-deficient subsoil to the surface and the burying of carbon-rich topsoil. In this review, we hypothesise that over the next ~30 years the new topsoil could incorporate large amounts of soil organic carbon (SOC) from the re-seeded sward vegetation and that the buried carbon will be retained. We assess the current capability of Irish grassland soils to sequester carbon and suggest a potential role of FIT during grassland renovation. An analysis of the distribution of grasslands in Ireland using the Land Parcel Identification System (LPIS) suggests that ~26% of Ireland's agricultural grasslands are suitable for FIT.
37. 题目: Cereal straw incorporation and ryegrass cover crops: the path to equilibrium in soil carbon storage is short
期刊: European Journal of Soil Science
作者: Johannes L. Jensen, Jørgen Eriksen, Ingrid K. Thomsen, Lars J. Munkholm, Bent T. Christensen
摘要: Reduced use of fossil energy by removing cereal straw for bioenergy potentially threatens soil organic carbon (SOC) storage. Straw incorporation plays a key role for SOC storage in cereal-based cropping systems but the use of cover crops may compensate for straw removal. However, assessing the SOC sequestration potential of management changes requires field experiments with long continued treatments and frequent soil sampling. Based on a field experiment initiated in 1981 on a sandy loam soil at Askov Experimental Station (Denmark), we examined the effect of annual additions of spring barley straw (0, 4, 8 and 12 Mg ha-1) and undersown ryegrass cover crop on SOC storage in the 0-20 cm layer. The effect of straw incorporation and cover crop on SOC was additive. At steady-state conditions, the SOC stock based on equivalent soil mass (SOC stockFM) increased 3.9, 6.7 and 9.3 Mg C ha-1 after annual incorporation of 4, 8 and 12 Mg straw ha-1, respectively. The ryegrass cover crop increased SOC stockFM by 3.3 Mg C ha-1 and thus almost compensated for removal of 4 Mg straw ha-1. An asymptotic regression model best described the temporal changes in SOC and showed that the effect of straw incorporation and ryegrass cover crop on SOC sequestration peaks after 10-15 years when a new equilibrium between input and output of C is reached. Clearly, reliable assessments of SOC sequestration potentials following changes in management require field experiments with frequent soil sampling until reaching steady-state conditions.
38. 题目: Mechanism of aging of biochars obtained at different temperatures from sewage sludges with different composition and character
作者: Anna Siatecka, Patryk Oleszczuk
摘要: The aim of this study was to determine the effect of abiotic aging of sewage sludge (SSL)-derived biochars on their physicochemical properties and in consequence on their stability. Biochars produced at 500 or 700 oC from SSLs with a different composition and properties were incubated at different temperatures (−20, 4, 20, 60, and 90 oC) for 6 and 12 months. Pristine and aged biochars were characterized in terms of their composition and properties using a range of complementary methods. The results showed that SSL-derived biochars will not be as stable as previously thought in the long term. The stability of the SSL-derived biochars was closely related to the content and character of C. The biochars that had more C in their composition and, apart from aromatic C, also aliphatic matter/carbon substances deposited in surface pores (i.e. those produced from SSL with a lower initial ash content and a lower degree of aromaticity) were less stable than the biochars with a lower C content and a typically aromatic character of C (i.e. those derived from SSL with a higher initial ash content and a higher degree of aromaticity). Their oxidation led to partial mineralization of aliphatic chains or organic surface film and manifested itself in a greater changes in their properties. The low-temperature biochars (BC-500) with lower aromaticity were found to be more susceptible to oxidation than the high-temperature ones (BC-700) with higher aromaticity. The more aromatic structure of C limited access of O2 molecules to biochar interior, due to which the processes occurring during aging were concentrated in their surface layer and their properties were less change. It can therefore be concluded that pyrolysis of SSL with higher aromaticity and a lower organic content and higher pyrolysis temperatures will lead to obtaining more stable SSL-derived biochars.
39. 题目: Phosphorus Binding by Lanthanum Modified Pyroaurite-like Clay: Performance and Mechanisms
期刊: ACS ES&T Engineering
作者: Yanyang Zhang, Bo Kong, Zhaoyang Shen, Jieshu Qian, Bingcai Pan
摘要: In situ immobilization of phosphorus (P) by using P binding agents is a facile and effective strategy for eutrophication control. Currently, the most successful commercial agent (Phoslock, a lanthanum modified bentonite, LMB) still suffers low P removal efficiency from natural waters of complex chemistry, largely due to the competitive complexation of the active La species by humic substances (HAs) and bicarbonate. Herein, we describe an attempt to address these issues by intercalating La into Mg/Fe layered double hydroxides, a pyroaurite-like anionic clay, to obtain a hybrid agent (denoted L-CMF-1.0) of phosphate capacity five times higher than that of LMB. More attractively, the binding stability and capacity of L-CMF-1.0 toward P were significantly enhanced in the presence of HAs and bicarbonate, resulting in a high La usage (P/La ratio at ∼1.30). A continuous P immobilization test in the simulated natural waters validates that the addition of L-CMF-1.0 at 0.12 g/L could result in an efficient P removal from 580 μg/L to <100 μg/L within 38 days, outperforming LMB within 10 days only under otherwise identical conditions. Such improvement results from the rational design of the agent structure, i.e., the host, not only contributes to the direct P uptake but also provides a flexible nanoshelter microenvironment to favor the specific La–P interaction under complex solution chemistry. This work is believed to shed new light on the rational design of P binding agent for enhanced eutrophication control.
40. 题目: Metal-rich hyperaccumulator-derived biochar as an efficient persulfate activator: Role of intrinsic metals (Fe, Mn and Zn) in regulating characteristics, performance and reaction mechanisms
期刊: Journal of Hazardous Materials
作者: Xinhua Wang, Peng Zhang, Cuiping Wang, Hanzhong Jia, Xiaofu Shang, Jingchun Tang, Hongwen Sun
摘要: Biochar has been widely used in advanced oxidation processes (AOPs) for the decomposition of organic contaminants. However, the role of intrinsic metals in hyperaccumulator biomass in the physico-chemical properties and performance of peroxodisulfate (PDS) activation by biochar is still unclear. This work employed hyperaccumulator biomass containing Fe, Mn and Zn, respectively. Result showed that as the pyrolysis temperature of the biochar increased, Fe was gradually reduced to iron oxide and Fe0, and Zn was reduced and volatilized; however, Mn remained in biochar in the form of MnS and CaMnO3 with high valence states. These thermochemical behaviors of intrinsic metals also facilitated graphitized structure growth and pore development (for Zn) and persistent free radicals (PFRs) generation (for Mn and Zn) in biochar, and these processes were crucial for imidacloprid degradation in biochar/PDS systems. Moreover, Fe/Zn@PB9/PDS showed better imidacloprid degradation performance, while Mn species in Mn@PB were catalytically inert. In addition, the radical pathway depending on ·SO4- and ·OH was the dominant pathway for imidacloprid degradation in the Fe@PB9/PDS systems, while the ·O2--mediated 1O2 pathway and 1O2-based nonradical pathway contributed more in the Zn@PB9/PDS systems. These results reveal the role of intrinsic metals in biochar-based catalysts and provide a reference for the preparation of green and efficient hyperaccumulator-derived biochar catalysts for AOPs.