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22701. 题目: Electrochemical behavior of biochar and its effects on microbial nitrate reduction: Role of extracellular polymeric substances in extracellular electron transfer Biochar is extensively used in the remediation of pollutants because of its diverse physicochemical properties. Biochar application can alter the activity of microbial communities involved in bioremediation. However, the electrochemical behavior of biochar and its potential effect on microbial nitrate reduction remains unknown. Electron transfer between microbial cells and electron donor or acceptor species is often across extracellular polymeric substances (EPS). However, the role of EPS in extracellular electron transfer remains unclear. In this study, we examined the electrochemical behavior of biochar and its effects on microbial nitrate reduction to elucidate the role of EPS in extracellular electron transfer (EET). The biochar prepared by the pyrolysis of Aspen wood chips at 400–600 °C. Electrochemical analysis using cyclic voltammetry, electrochemical impedance spectrum, and chronoamperometry showed that biochars could donate and accept electrons. BC 400, BC 500, and BC 600 had an electron donating capacity of 1.03 mmol e− g−1, 0.9 mmol e− g−1, and 0.8 mmol e− g−1, respectively. Furthermore, biochars prepared at 400 °C significantly enhanced the microbial nitrate reduction process. The phenol OH and quinone CO surface functional groups on the biochar probably contributed to the overall electron exchange, and this accelerated the nitrate reduction. Electrochemical analysis revealed that the outer membrane c-type cytochrome and flavin proteins from the biofilm were involved in the electron transfer process, with the EPS acting as a transient media for the microbially-mediated EET. Overall, this study suggested that biochar may be effectively used as an eco-friendly material for the enhancement of microbial denitrification. | |||||
22702. 题目: Combining high electron transfer efficiency and oxidation resistance in nZVI with coatings of microbial extracellular polymeric substances to enhance Sb(V) reduction and adsorption In this work, we prepared microbial extracellular polymeric substances-coated nano zero valent iron () for Sb(V) removal. Batch adsorption experiments showed that the synthesized had superior maximum adsorption capacity (202 mg/g at pH = 5) for Sb(V), much higher than that of bare nZVI especially under nonacidic conditions. The adsorption results fit the pseudo-second-order kinetic model and the Redlich-Peterson model well, implying that the adsorption was more like a chemical adsorption process. The spectral analysis showed that EPS could protect inner Fe0 from air, preventing nZVI from generating a passivation layer on the surface, and decreasing the concentration of hydroxyl radicals in aqueous environment, which increased the reactivity of nZVI and strengthened the reducibility and adsorbability of nZVI. The coated EPS can improve the reactivity of nZVI instead of inhibiting its electron transfer. Moreover, the electrostatic repulsion between and Sb(OH)6− was decreased compared to that of bare nZVI after the introduction of EPS. The functional groups of EPS could play a significant role in the reduction adsorption, especially under alkaline conditions where nZVI was passivated. This work proved that has great prospects in simultaneously combining the reduction activity of nZVI in water and its stability in air. | |||||
22703. 题目: Hydochar and biochar: Production, physicochemical properties and techno-economic analysis Utilization of natural, abundant, and renewable resources for the production of carbon materials with simple and energy-efficient processes is an upsurge interest. The production processes and resultant biochar can address widespread concerns such as climate change, energy crisis, and environmental pollution. The properties of produced chars (biochar/hydrochar) depend on the production methods, feedstock's, and operating parameters, which significantly affect their use for various applications. In this review, production, physiochemical properties, and techno-economic analysis of chars are summarized. This review provides the fundamentals and reaction mechanism of char's production methodologies. Physicochemical properties based on chemical composition, functional groups, structure, porosity, and shapes have been compared. The effects of operating parameters on the physicochemical properties of chars are discussed. In addition, this review offers insights on new directions for char production and research in the future, based on the updated and detailed investigation of energy balance with economy of char's production methodologies. | |||||
22704. 题目: Wood-based activated biochar to eliminate organic micropollutants from biologically treated wastewater Implementing advanced wastewater treatment (WWT) to eliminate organic micropollutants (OMPs) is a necessary step to protect vulnerable freshwater ecosystems and water resources. To this end, sorption of OMP by activated carbon (AC) is one viable technology among others. However, conventional AC production based on fossil precursor materials causes environmental pollution, including considerable emissions of greenhouse gases. In this study, we produced activated biochar (AB) from wood and woody residues by physical activation and evaluated their capability to eliminate OMPs in treated wastewater. Activated biochar produced under optimized conditions sorbed 15 model OMPs, of which most were dissociated at circumneutral pH, to the same or higher extent than commercial AC used as a reference. While wood quality played a minor role, the dosage of the activation agent was the main parameter controlling the capacity of ABs to eliminate OMP. Our results highlight the possibility for local production of AB from local wood or woody residues as a strategy to improve WWT avoiding negative side effects of conventional AC production. | |||||
22705. 题目: Effects of abandonment management on soil C and N pools in Moso bamboo forests Moso bamboo (Phyllostachys Pubescens) forests exhibit a great potential to sequestrate carbon dioxide from atmosphere and to mitigate global climate change. However, they were increasingly under abandoned (i.e., no fertilization, the low intensity and frequency of felling and bamboo shoot digging) due to decreasing economic values of bamboo-related products and increasing labor cost. So far, the changes in soil carbon (C) and nitrogen (N) pools in bamboo forests following abandonment are poorly addressed. In this study, Moso bamboo stands under intensively management and abandonment for different durations were sampled to explore the C and N pool dynamics at the top 40 cm soil. We classified abandonment durations into three categories: discarded or abandoned management for 1–6 years (DM-I), 7–12 years (DM-II) and 13–18 years (DM-III). Our results indicated that (1) soil organic carbon (SOC) storage was significantly increased with abandonment management compared with intensive management (Control, CK), but the durations of abandonment management had no significant effects on SOC. Microbial biomass carbon (MBC) concentration increased from DM-I to DM-III in the 0–40 cm soil layer (P < 0.01), and water-soluble organic carbon (WSOC) concentration decreased through DM-I (P < 0.01). (2) Abandonment management did not significantly affect soil total nitrogen (TN) storage at depth of 0–40 cm, with 9.54 Mg ha−1 for CK, 9.59 Mg ha−1 for DM-I, 9.89 Mg ha−1 for DM-II and 9.69 Mg ha−1 for DM-III. Water-soluble organic nitrogen (WSON) concentration significantly decreased from CK to DM-III. Ammonium nitrogen (NH4+-N) concentration increased from DM-I to DM-III (P < 0.01), and nitrate nitrogen (NO3−-N) concentration decreased from CK to DM-III (P < 0.01). The results of the effects of abandonment durations on soil properties in Moso bamboo forests provide valuable information for forest restoration and management. | |||||
22706. 题目: Are there environmental or agricultural benefits in using forest residue biochar in boreal agricultural clay soil? Short-term agronomic and environmental benefits are fundamental factors in encouraging farmers to use biochar on a broad scale. The short-term impacts of forest residue biochar (BC) on the productivity and carbon (C) storage of arable boreal clay soil were studied in a field experiment. In addition, rain simulations and aggregate stability tests were carried out to investigate the potential of BC to reduce nutrient export to surface waters. A BC addition of 30 t ha−1 increased soil test phosphorus and decreased bulk density in the surface soil but did not significantly change pH or water retention properties, and most importantly, did not increase the yield. There were no changes in the bacterial or fungal communities, or biomasses. Soil basal respiration was higher in BC-amended plots in the spring, but no differences in respiration rates were detected in the fall two years after the application. Rain simulation experiments did not support the use of BC in reducing erosion or the export of nutrients from the field. Of the C added, on average 80% was discovered in the 0–45 cm soil layer one year after the application. Amendment of boreal clay soil with a high rate of BC characterized by a moderately alkaline pH, low surface functionalities, and a recalcitrant nature, did not induce such positive impacts that would unambiguously motivate farmers to invest in BC. BC use seems unviable from the farmer's perspective but could play a role in climate change mitigation, as it will likely serve as long-term C storage. | |||||
22707. 题目: Accumulation of organic matter in a mesotidal Mediterranean lagoon (Boughrara, Tunisia) In the frame of the COZOMED project, concentrations of organic matter (TOC, DOC, POC) were monitored during two seasonal field campaigns (autumn, October 2016 and spring, April 2017) in the Boughrara Lagon, Tunisia. Results indicate strong influence of the seawater exchange and circulation, on the organic matter accumulation inside the lagoon, visible through a significant correlation between TOC and salinity in both seasons. Two times higher concentration of TOC (up to 5.5 mg/l) was recorded in autumn, when high salinity water (46 psμ) was present in the lagoon. POC made a relatively small percentage of TOC in autumn samples when high accumulation of TOC, especially its DOC fraction can be related with the remineralization processes and zooplankton-mediated release of DOC. Indeed, PCA analysis identified DOC as the most significant factor influencing the observed variability in autumn samples, and correlated to NH4+ (p < 0.05) in surface water, while POC was significantly (p < 0.05) correlated to chlorophyll a. During spring, organic matter in the lagoon was depth-dependent and under the high influence of salinity and temperature, and in the surface correlated to N03-. Satellite data on lagoon water optical properties appear to support changes in measured organic matter concentrations indicating different optical properties of the water inside the lagoon during spring and autumn seasons. The ocean color remote sensing, with properly validated and tested robust algorithms, accommodating optically shallow waters, can provide valuable tools for monitoring and timely detection of possibly detrimental changes inside the lagoon. | |||||
22708. 题目: Effects of woody biochar on dry thermophilic anaerobic digestion of organic fraction of municipal solid waste This study presents the results of semi-pilot scale anaerobic digestion tests conducted under dry thermophilic conditions with the addition of biochar (6% on fresh mass basis of inoculum), derived from an industrial gasification plant, for determining biogas and biomethane production from organic fraction of municipal solid waste. By using two types of inocula (from a full-scale dry anaerobic digestion plant and from lab-scale biomethanation tests), the obtained experimental results did not show significant increase in methane yield related to the presence of biochar (330.40 NL CH4 kgVS−1 using plant inoculum; 335.41 NL CH4 kgVS−1 using plant inoculum with biochar, 311.78 NL CH4 kgVS−1 using lab-inoculum and 366.43 NL CH4 kgVS−1 using lab-inoculum with biochar), but led to significant changes in the microbial community composition. These results are likely related with the specific biochar physical-chemical features and low adsorption potential. Resulting digestate quality was also investigated: biochar-enriched digestates were characterized by increased biological stability (809 ± 264 mg O2 kgVS−1 h−1 vs. 554 ± 76 mg O2 kgVS−1 h−1 for biochar-free and biochar-enriched digestates, respectively), lower heavy metals concentrations (with the exception of Cd), but higher polycyclic aromatic hydrocarbons content, with a reported maximum concentration of 8.9 mgPAH kgTS−1 for biochar-enriched digestate derived from AD test with lab-inoculum, which could trigger non-compliance with regulation limits for agricultural reuse of digestates. However, phytotoxicity assessments showed a decreased toxicity of biochar-containing digestates when compared to biochar-free digestates. | |||||
22709. 题目: Biochar addition leads to more soil organic carbon sequestration under a maize-rice cropping system than continuous flooded rice Crop rotation of flooded rice with an upland crop like maize on previous continuous paddy soils is an emerging cropping system in South China. A four-year experiment was conducted at a research area in Hunan province, having a long history of double paddy-rice cropping throughout the year. Maize was introduced as an upland crop in rotation with paddy rice, thus providing two parallel cropping systems i.e., the previous flooded rice-rice (R–R) and the new maize-rice rotation (M–R) systems. We used three treatments in both cropping systems; namely, farmer's practice (without external C input) as a control, straw addition, and biochar addition. The straw and biochar were added to soil in late rice season on an equal C input basis (3000 kg C ha−1yr-1). In the R–R plots, rice straw was added while in M–R plots maize straw was added during late rice field preparation. Our results show that there were no changes in soil organic carbon (SOC) concentration when R–R was replaced by M–R rotation. Straw addition had no effect on SOC but improved late rice yield. Biochar addition significantly increased SOC and late rice yield in both cropping systems. Moreover, biochar addition resulted in a more significant accumulation of SOC (9% higher) in M–R than R–R. Among soil aggregates, only the 0.25–2 mm fraction had a significantly higher SOC concentration with biochar relative to the control and straw return; and this increase was significantly more pronounced under M–R (28% higher) than R–R cropping system. In general, a significantly higher proportion of small macro-aggregates (0.25–2 mm) were found under M–R, while smaller aggregates (0.05–0.25 and <0.05 mm) were more abundant under R–R. δ13C analyses from M–R plots reveal that the quantity of maize-derived C was marginally higher in the straw treatment than control, but this was not reflected in any significant impact on total SOC of the bulk soil or of aggregates. In conclusion, no detectable changes in SOC were observed over four years experimental period following shift from R-R to M-R cropping system. M-R system with biochar addition led to higher productivity and environmental benefits. | |||||
22710. 题目: Chemodiversity of Soil Dissolved Organic Matter | |||||
22711. 题目: Effect of quorum quenching on EPS and size-fractioned particles and organics in anaerobic membrane bioreactor for domestic wastewater treatment Quorum quenching (QQ) has been applied as a promising membrane fouling control strategy for anaerobic membrane bioreactors (AnMBRs). Nevertheless, long-term operation of AnMBRs for real domestic wastewater (DWW) treatment needs to be systematically studied to evaluate comprehensive membrane fouling mechanisms and bioprocess performance. In this study, the impact of QQ on membrane fouling was investigated using a quorum quenching AnMBR (QQAnMBR) deploying a bead-entrapped facultative quorum quenching consortium (FQQ) to treat DWW. FQQ was shown to prolong membrane filtration operation by an average of 75%. Reduced proteins (p < 0.005) and carbohydrates (p < 0.005) in the extracellular polymeric substances (EPS) of mixed liquor (ML) were key differentiators that led to lower cake layer (CL) formation. Additionally, reduced biopolymers production (p < 0.05) in EPS improved sludge dewaterability. The findings suggested that QQ could alter fluorescent microbial metabolites of both EPS and CL as unveiled by excitation-emission matrix spectra pattern. Furthermore, colloidal particles (i.e., particles with size larger than 0.45 μm in ML supernatants) production was retarded by QQ, thereafter, also contributed to the reduced CL formation. Pore blockage was slightly increased by QQ, which might be attributed to pore blockage by large (∼230 nm) and small organic compounds (∼51 nm) in soluble microbial products (SMP). However, QQ had no significant impact on organic concentration of SMP, and QQ was not associated with particle size distribution of biomass. QQ performance was further affirmed through suppressed production of C4-HSL, 3-OXO-C6-HSL, and C6-HSL. The overall AHLs degradability of FQQ was well-maintained even after five membrane service cycles (total operation of 70 d). Moreover, QQ had no compromised impact on treatment performance (i.e., chemical oxygen demand (COD) removal and methane yield). Collectively, this study bridged the knowledge gap to bring forward QQ technology in AnMBR for widespread domestic wastewater treatment application. | |||||
22712. 题目: Accumulation of organic carbon in a large canyon reservoir in Karstic area, Southwest China | |||||
22713. 题目: Disentangling the role of extracellular polysaccharides in desiccation tolerance in lichen‐forming microalgae. First evidence of sulfated polysaccharides and ancient sulfotransferase genes Trebouxia sp. TR9 and Coccomyxa simplex are desiccation‐tolerant microalgae with flexible cell walls, which undergo species‐specific remodelling during dehydration‐rehydration (D/R) due to their distinct ultrastructure and biochemical composition. Here, we tested the hypothesis that extracellular polysaccharides excreted by each microalga could be quantitatively and/or qualitatively modified by D/R. Extracellular polysaccharides were analysed by size exclusion and anion exchange chromatography, specific stains after gel electrophoresis and GC/MS of trimethylsilyl derivatives (to determine their monosaccharide composition). The structure of a TR9 sulfated polymer was deduced from NMR analyses. In addition, sugar‐sulfotransferase encoding genes were identified in both microalgae and their expression was measured by RT‐qPCR. D/R did not alter the polydispersed profile of extracellular polysaccharides in either microalga but did induce quantitative changes in several peaks. Furthermore, medium‐low‐sized uronic acid‐containing polysaccharides were almost completely substituted by higher molecular mass carbohydrates after D/R. Sulfated polysaccharide(s) were detected, for the first time, in the EPS of both microalgae, but only increased significantly in TR9 after cyclic D/R, which induced a sugar‐sulfotransferase gene and accumulated sulfated ß‐D‐galactofuranan(s). Biochemical remodelling of extracellular polysaccharides in aeroterrestrial desiccation‐tolerant microalgae is species‐specific and seems to play a role in the response to changes in environmental water availability. This article is protected by copyright. All rights reserved. | |||||
22714. 题目: Efficient removal of perfluorooctane sulphonate by nanofiltration: Insights into the effect and mechanism of coexisting inorganic ions and humic acid The removal of perfluorooctane sulphonate (PFOS) with coexisting substances is very important. Inorganic ions and humic acid (HA) commonly coexist and may influence PFOS removal performance. However, there is little information on the capacity for systematic PFOS removal in the presence of inorganic ions and HA during nanofiltration (NF) process. In this paper, the impact of the coexistence of anions, cations, and HA on PFOS removal were investigated by NF. More specifically, the effect and interaction of anions, cations, and HA on PFOS removal performance and mechanism were examined. The PFOS removal rejection increased from 92% to 99% when HA was present together with both cations and anions. The higher the valence of the inorganic ion was, the greater the PFOS rejection was. The sieving effect was dominant in the improvement of PFOS removal by the presence of cations. The electrostatic repulsion played an important role in the improvement of PFOS removal by the presence of anions. Furthermore, density functional theory (DFT) was applied to calculate the interaction between PFOS molecules, cations, and HA. Corresponding DFT structures and thermodynamics parameters were obtained. It showed that the Ca2+ ions could more easily bridge two PFOS than one PFOS, HA could more easily coordinate with both Ca2+ and PFOS molecules. The increase of PFOS size after the coordination reaction results in the improvement of the sieving effect. Additionally, other analyses including X-ray photoelectron spectroscopy, atomic force microscopy, and the surface zeta potential also demonstrated the sieving effect mainly governed PFOS removal in coexistence with HA and cations. The electrostatic repulsion was dominant in PFOS separation performance in coexistence with HA and anions. | |||||
22715. 题目: Bacterial and archaeal taxa are reliable indicators of soil restoration across distributed calcareous grasslands Land use intensification can reduce soil carbon stocks and changes microbial community biodiversity and functionality. However, there is a lack of consensus on whether management consistently affects microbial biodiversity across geographic scales, and how this relates to altered soil function. From a regulatory and monitoring perspective, there is a need to identify functionally relevant indicators of land use in order to evaluate the progress of soil restoration approaches. We performed a landscape scale survey of unimproved calcareous grasslands paired with local arable contrasts, and assessed the consistency of responses in a variety of soil, biotic and functional measures. In addition, adjacent grasslands undergoing restoration were assessed to identify soil microbial indicators of recovery. Organic matter content was consistently larger in grasslands than in arable fields, and increased with time in the restoring sites. Molecular comparisons of grassland versus arable soils revealed numerous bacterial, archaeal and fungal indicators, with more representatives of Ca. Xiphinematobacter, DA101, Bradyrhizobium, Rhodoplanes, Mycobacteria and Mortierella in old grassland soils, while Nitrososphaera, Sporosarcina and Alternaria infectoria were more abundant in arable soils. Extracellular enzymatic responses were more variable with none of the eight investigated enzymes being consistent indicators of grassland or arable soils. Correlation analyses, incorporating the molecular and enzymatic responses across all surveyed soils, revealed that molecular indicators were more strongly correlated with soil organic matter increases with restoration of arable soils. Our results highlight that microbial taxa are among the most sensitive indicators of soil restoration, and we identify consistent responses of specific taxa to management across geographic scales. This discovery will be important for both the instigation and monitoring of the soil restoration. This article is protected by copyright. All rights reserved. | |||||
22716. 题目: Fencing decreases microbial diversity but increases abundance in grassland soils on the Tibetan Plateau Fencing usually increases soil organic carbon and nutrients and eventually enhances soil microbial diversity, however with different or even conflicting results, the mechanisms underlying the diversity reduction remain unclear. Aiming to reveal the mechanism of diversity reduction, we explored the soil microbial diversity and community structure in fencing (5‐years and 10‐years) and grazing during a growing season in arid and semi‐arid steppe, using Illumina sequencing of 16S and 18S rRNA genes. The results revealed that fencing and season both substantially increased soil total organic carbon (TOC), while the enhancing TOC substantially reduced soil pH. Fencing significantly increased bacterial and eukaryotic abundance due to the enhancing TOC, which was indicated by positive correlation (p < 0.05). Contrastingly, fencing significantly decreased bacterial and eukaryotic diversity. Our results further revealed that fencing‐ and season‐driven change in soil water content and soil pH played key roles in reducing the bacterial and eukaryotic diversity, respectively. Distance‐based linear model demonstrated that fencing dominantly drove the soil bacterial and eukaryotic community variations by explaining 15.64% and 24.88%, respectively, and redundancy analysis showed that the fencing effect was dependent on growing months. Bacteria were dominanted by Cyanobacteria and Proteobacteria, and eukaryotes were dominanted by Streptophyta, Ascomycota and Basidiomycota. Cyanobacteria relative abundance remained stable from May to September in fencing but substantially increased in grazing. Our findings offer a new insight into the mechanism of the soil microbial diversity reduction, and reveal the season‐dependency of fencing effect in arid and semi‐arid grasslands. This article is protected by copyright. All rights reserved. | |||||
22717. 题目: The influence of soil warming on organic carbon sequestration of arbuscular mycorrhizal fungi in a sub-arctic grassland A substantial portion of grassland photosynthates is allocated belowground to arbuscular mycorrhizal fungi (AMF), but controversy remains about whether this carbon (C) contributes to soil organic carbon (SOC) under warming. The goal of this study was to investigate how AMF biomass and C sequestered by AMF (CNew) are influenced by soil warming. We estimated the AMF biomass and CNew, assumed to be mostly AMF necromass, in mycelial ingrowth bags buried for 1, 2, or 3 years in soil under warming (∼+0.5–16.4 °C). The AMF biomass had a positive, curvilinear response to warming gradients after one year of burial. About 107 g C m−2 of CNew accumulated over the three years and ∼12% of this C was from glomalin-related soil protein. Modelling suggested the production rate of AMF biomass was 153 g C m−2 yr−1 with a rapid (36–75 days) turnover while AMF necromass turnover was much slower (1.4 ± 0.2 yr−1). Warming duration (7–9 years vs. > 50 years) did not have significant influence on AMF biomass or CNew (P > 0.05). Our results suggest that AMF are more tolerant to increases in temperature than other microbes or fine roots. The dramatic loss of soil C and stable soil aggregates under warming found earlier at this site were not attributed to a decrease AMF biomass or CNew. Despite a low AMF standing biomass, its contribution to SOC may be substantial. | |||||
22718. 题目: The contribution of prokaryotes and terrestrial plants to Maldives inter-atoll sapropels: Evidence from organic biomarkers The composition of organic matter in early Miocene sediment cores obtained from International Ocean Discovery Program Expedition 359 (IODP Exp. 359) was analysed using tetramethylammonium hydroxide (TMAH) thermochemolysis, a method used to determine concentrations of lignin phenols, fatty acids, sterols and hopanoids. These early Miocene sediment cores contain thick sequences (∼100 m) of interbedded light (organic-poor) and dark (organic-rich) sedimentary layers. A total of 49 samples from cores between 704.4 mbsf to 803.95 mbsf (∼20–23 Ma) at Site U1466 (518 m water depth) was selected with particular emphasis placed on the dark layers, although the light layers were also sampled. While organic compounds were below detection limits in the lighter coloured sedimentary layers, the dark layers, with concentrations of organic carbon up to 20%, contained varying concentrations of all analysed compounds. Although sterols were present, hopanoids were more abundant in the dark layers. The contribution of prokaryotic organisms, estimated from the ratio (hopanols and hopanoic acids/[sterols + hopanols and hopanoic acids]), indicates that it was prokaryotic organisms rather than eukaryotic organisms that contributed the majority (∼90%) of the organic matter in the dark layers. In conjunction with this record, more negative δ15N values in the darker layers suggest that the prokaryotic organisms were nitrogen-fixing microorganisms (presumably cyanobacteria). The long-to-short fatty acid ratios, together with sterol distributions and the concentration of lignin phenols, suggest the input of terrestrial plant material occurred during a high total organic carbon (TOC) interval (∼770–810 mbsf), which coincides with more negative carbon isotope ratios. Additionally, the long-to-short fatty acid ratio in this interval was significantly higher in the dark layers than the light layers, suggesting that terrestrial environments suitable for vegetation growth expanded during the interval represented by the dark layers. Furthermore, the ratio of cinnamyl lignin phenols to vanillyl lignin phenols (C/V) is relatively high during these intervals. From these biomarker tracers, we speculate that the terrestrial vegetation was dominated by herbaceous plants adapted to frequent sea-level changes. | |||||
22719. 题目: Phase changes of continuous cropping obstacles in strawberry (Fragaria × ananassa Duch.) production Soil ecology plays an important role in the growth and health of plants. Research suggests that long-term monocropping may lead to soil ecological disorders. In this study, we aimed to understand the reasons for the decrease in plant productivity stemming from long-term monoculture cropping. Greenhouse studies were conducted to determine the cause of continuous cropping (CC) obstacles in soils under 12 years of continuous strawberry (Fragaria × ananassa Duch.) production. The data suggested that CC led to three phases of changes in abiotic and biotic soil factors. In phase I (CC for 2–6 years), significant changes were observed only in soil physicochemical properties, such as the pH, total nitrogen (TN), ammonium nitrogen (NH4+-N), available phosphorus (AP), available potassium (AK) and soil organic matter (SOM), which obviously changed from the second year to the sixth year. In phase II (CC for 6–8 years), two biotic factors, key fungi such as Fusarium, Humicola and Arthrobotrys and soil nematodes, i.e., populations and communities of nematodes, started to change significantly in terms of their abundance. In phase III (CC for >8 years), the accumulation of phenolic acids, i.e., p-hydroxybenzoic acid (p-HBA), ferulic acid (FA), p-coumaric acid (p-CA) and cinnamic acid (CA), significantly inhibited crop growth, and the abundance of key bacteria, including Bacillus, Sphingomonas and Sphingopyxis, started to change significantly from the eighth CC year. The results in this study provide useful information for solving CC obstacles in strawberry production. | |||||
22720. 题目: Comparing the effects of soil fauna on litter decomposition and organic matter turnover in sustainably and conventionally managed olive orchards Soils and crops in Mediterranean agrosystems are vulnerable to climate change and environmental stresses, and they will be more and more in the next future. In this scenario, soil organic matter (SOM) plays a crucial role and its level is principally determined by the continuous physical and chemical action of soil fauna. While the importance of microorganisms in fruit agrosystems has been extensively and recently highlighted, the role of soil fauna - and particularly of macrofauna - to ecosystem services has been often overlooked. On this basis, the aim of this study was to characterize and compare C/N dynamics and other soil physicochemical parameters, soil macrofauna abundance, bioturbation and litter/SOM decomposition indices in a Mediterranean olive (Olea europaea L.) orchard subjected to two different soil management systems (namely sustainable, Smng, and conventional, Cmng) for 18 years. The adoption of the Smng system significantly increased almost three times the abundance of earthworms and two times that of other soil macrofauna. Bioturbation due to soil fauna and roots was significantly higher in the Smng system, and this caused a significantly faster SOM decomposition measured both in 90-day incubated local litter bags (decomposition constant = 0.092 and 0.072 in the Smng and Cmng system, respectively) and in tea bags (decomposition rate constant = 0.018 and 0.010 in the Smng and Cmng system, respectively). Soil C and N dynamics were also affected by different soil management. The results highlighted that the soil chemical quality of the Smng system is the result of the higher abundance and activity of soil fauna, in terms of enhanced litter decomposition and bioturbation. From the general analysis of the data obtained, it emerged that the role of soil fauna should be seriously taken into account in land management strategies not exclusively oriented to fruit yield and quality, but also to soil fertility restoration. | |||||
