论文检索 |
|||||
|
总访问量：4853208次 总访客量：243009人 | |||||
| 关键词:... | |||||
| 期刊：... | |||||
所有论文 |
|||||
22801. 题目: Drought changed soil organic carbon composition and bacterial carbon metabolizing patterns in a subtropical evergreen forest Subtropical forests are considerable carbon sinks in the northern hemisphere, yet are increasingly suffering from the impact of extreme drought. To better understand the dynamics and kinetics of forest soil carbon storage under long-term drought, a rainfall-reduction experiment was established in a subtropical evergreen forest of eastern China. Soil organic carbon (SOC) composition, microbial carbon metabolism and the interactions with soil microbial community structure were investigated across different soil aggregate size fractions. After five years' treatment of rainfall reduction, a significant loss of large macroaggregates, as well as an increase of microaggregates by over 100% was observed. Meanwhile, drought changed the composition of SOC, reducing the non-hydrolyzed carbon and humin contents in large- to medium-size macroaggregates. Microbial metabolizing capacity of polymeric compounds was also reduced especially in the above aggregate fractions, whereas the utilization of small-molecular compounds was more impacted in small macroaggregates and microaggregates. The changes in carbon metabolizing patterns were further associated with the abundance changes of specific microbial taxa, revealing the microbially mediated mechanism of soil carbon metabolism under long-term drought. In addition, carbon metabolism in microaggregates was particularly sensitive to the changes of soil moisture, suggesting long-term drought may continually influence the functional resistance of the microbial communities. Taken together, our results provide insights into how biotic and abiotic processes together influence the SOC metabolizing processes, continued monitoring and investigation of which shall contribute to better understanding of the dynamics and kinetics of SOC storage under the impact of long-term drought. | |||||
22802. 题目: Compaction conditions affect the capacity of biochar-amended sand filters to treat road runoff Amending roadside soil with adsorbents such as biochar can help remove pollutants from road runoff. To maintain soil stability, the roadside soil with biochar requires compaction. However, it is unknown how compaction conditions affect the capacity of biochar-augmented roadside biofilters to infiltrate stormwater and remove pollutants. This work examines the effect of compaction conditions on the release of biochar particles disintegrated during compaction, and the change in their capacity to infiltrate stormwater and remove E. coli. The net loss of biochar particles by mobilization with stormwater was insignificant compared to the biochar remained in the filters. The initial release of biochar particles in wet-compacted biochar columns was greater than that in dry-compacted biochar. The results revealed that compaction can affect the release of biochar particles in a series of three-step processes: generation of particles by disintegration of large biochar under compaction, diffusion of particles deposited near grain walls to bulk pore water, and transport and retention of particles in constricted pore paths based on pore water connectivity. Under similar conditions, compost columns released more particles than biochar columns, suggesting biochar is more stable than compost under compaction. E. coli removal in wet-compacted columns was greater than removal in dry-compacted columns, owing to greater pore path connectivity in wet-compacted columns. These results indicate that addition of moisture during compaction can increase contaminant removal, initial particle release, and infiltration capacity of biochar-augmented sand filters for road runoff treatment. The results would help develop design guidelines for roadside stormwater treatment system that requires compaction of filter media. | |||||
22803. 题目: Short term effects of biochar with different particle sizes on phosphorous availability and microbial communities Despite the increasing interest for biochar as a soil amendment, a knowledge gap remains on different particle size of biochar on soil phosphorous (P) availability and its impacts on microbial community. We hypothesized that biochar particle size and incubation temperature can significantly influence soil P availability and microbial community in subtropical acidic soil. A laboratory incubation study was established to investigate the effects of soil pH, available P and soil microbial responses to biochar addition having varying particle sizes using paddy soil and red soil under different incubation temperatures (15 °C & 25 °C). Biochar produced via pyrolysis of spent mushroom substrate feedstock was sieved into three particle sizes ((≤0.5 mm (fine), 0.5–1.0 mm (medium) and 1.0–2.0 mm (large)). The results exhibited that the fine particle biochar resulted in significantly higher release of P, soil pH, available P and bacterial species richness while simultaneously reducing the activities of phosphatase enzyme in both soils. Apprehending the impact of biochar particle size and incubation temperature, principal coordinate analysis (PCoA) predicted that soil microbial communities with fine particle biochar and high incubation temperature (25 °C) clustered separately. Redundancy analysis depicted that fine particle biochar had a direct association with available P and soil pH while high incubation temperature depicted a strong affinity for microbial communities. Hence, it is suggested that fine particle biochar and high incubation temperature may provide better habitat for microorganisms compared to the other particle sizes which may be due to improved soil pH and available P. However, a long term study of different biochar particles application in subtropical acidic soil needs to be pursued further for a more comprehensive understanding on this issue. | |||||
22804. 题目: Assessment of a fast method to predict the biochemical methane potential based on biodegradable COD obtained by fractionation respirometric tests The biochemical methane potential test (BMP) is the most common analytical technique to predict the performance of anaerobic digesters. However, this assay is time-consuming (from 20 to over than 100 days) and consequently impractical when it is necessary to obtain a quick result. Several methods are available for faster BMP prediction but, unfortunately, there is still a lack of a clear alternative. Current aerobic tests underestimate the BMP of substrates since they only detect the easily biodegradable COD. In this context, the potential of COD fractionation respirometric assays, which allow the determination of the particulate slowly biodegradable fraction, was evaluated here as an alternative to early predict the BMP of substrates. Seven different origin waste streams were tested and the anaerobically biodegraded organic matter (CODmet) was compared with the different COD fractions. When considering adapted microorganisms, the appropriate operational conditions and the required biodegradation time, the differences between the CODmet, determined through BMP tests, and the biodegradable COD (CODb) obtained by respirometry, were not significant (CODmet (57.8026 ± 21.2875) and CODb (55.6491 ± 21.3417), t (5) = 0.189, p = 0.853). Therefore, results suggest that the BMP of a substrate might be early predicted from its CODb in only few hours. This methodology was validated by the performance of an inter-laboratory studyconsidering four additional substrates. | |||||
22805. 题目: Combined effects of soil fertility and vegetation structure on early decomposition of organic matter in a tropical riparian zone Monitoring forests undergoing restoration is important to evaluate not only the development of trees, but also the recovery of ecosystem functions. The decomposition of the organic matter is an important ecological process, and nutrient cycling in ecosystems is a good indicator of forest ecosystem functions because it responds to physical, chemical, and biological characteristics of the vegetation and the soil. We hypothesized that both soil fertility and vegetation structure have direct and positive effects on decomposition processes. We used the Tea Bag Index (Keuskamp et al., 2013) to evaluate early decomposition of the organic matter in three land use categories, pasture, riparian forest undergoing restoration, and riparian forest remnant. Each category extended along a gradient of soil nutrients, enabling to jointly evaluate the effects of soil nutrients and vegetation structure on the decomposition process, using structural equations models to also describe the covariance between soil nutrients and vegetation. The decomposition rates (k) were negatively related to vegetation development, possibly due to less light in the forest floor, and less activity of the decomposer community. On the other hand, soil fertility had direct positive effects on k, possibly with higher microbial activity due to higher nutrient availability. The stabilization factor (S) was not influenced by soil nutrients or vegetation structure. However, in the riparian forest remnant plots, S increased with soil base saturation, indicating an interaction between the effects of soil fertility and land use category. Therefore, the decomposition process in this system responded to soil fertility and vegetation structure, but the magnitude of these effects varied with land use. The monitoring of this ecosystem function to evaluate ecosystem recovery should include simultaneously both soil and vegetation variables. | |||||
22806. 题目: Removal of Cadmium (II) using water hyacinth (Eichhornia crassipes) biochar alginate beads in aqueous solutions Biochar produced from water hyacinths (Eichhornia crassipes) has been demonstrated to be an effective adsorbent for the removal of certain heavy metals and as a means of control for this highly invasive species. This study involved examined the Cd2+ sorption dynamics of an alginate encapsulated water hyacinth biochar (BAC) generated at different temperatures and modified using ferric/ferrous sulfate (MBAC). The maximum Cd2+ sorption occurred at a pH of 6 and at a solution temperature of 37 °C. Sorption equilibria for the biochar-alginate capsule (BAC) and modified biochar-alginate capsule (MBAC) treatments fit both the Langmuir (R2 = 0.876 to 0.99) and Freundlich (R2 = 0.849 to 0.971) equations. Langmuir isotherms had a better fit than the Freundlich isotherms, with maximum sorption capacities ranging from 24.2 to 45.8 mg Cd2+ g−1. Larger KL values in Freundlich modeling suggest strong bonding of the BAC and MBAC sorbents to Cd2+, with values of KL in the MBAC treatments ranging between 31 and 178% greater than the BAC treatments. Cd2+ sorption followed pseudo first-order kinetics (R2 = 0.926 to 0.991) with greater efficiency of removal using treatments with biochar generated at temperatures >500 °C. Results from this study highlight the potential for biochar-alginate capsules derived from water hyacinth to be effective for the removal of Cd2+ from wastewaters. | |||||
22807. 题目: Temporal variation of soil organic carbon pools along a chronosequence of reforested land in Southwest China Land use changes have a great impact on carbon (C) cycling of terrestrial ecosystems by changing both the C inputs and mineralization rates. It not only results in variations of SOC stocks, but that the SOC properties could also change after vegetation conversions. In this study, we collected soil samples in a series of forests converted from croplands at different times in Southeast China. The effects of the reforestation on SOC pools and stabilities were investigated based on information of SOC contents, SOC fractions (active, intermediate and passive C) and C:N ratios. The organic carbon (OC) contents of the bulk soil and soil fractions increased with the forest ages in both topsoils (0–10 cm) and subsoils (40–50 cm). The increase rates of the active C were higher than those of the intermediate and passive C. As a result, the proportion of the active C increased with the forest ages, which would result in an increase of SOC instabilities. This was confirmed by the observation that the C:N ratio of the bulk soil increased with the forest ages. Our results implied that the C sink potential of the forest soil is to a large extent determined by the forest age. | |||||
22808. 题目: Predicting Aqueous Adsorption of Organic Compounds onto Biochars, Carbon Nanotubes, Granular Activated Carbons, and Resins with Machine Learning | |||||
22809. 题目: Abiotic and Biological Degradation of Atmospheric Proteinaceous Matter Can Contribute Significantly to Dissolved Amino Acids in Wet Deposition | |||||
22810. 题目: Nitrogen deposition enhances plant-microbe interactions in a semiarid grassland: The role of soil physicochemical properties Rapidly increasing atmospheric nitrogen (N) deposition may affect plants, microbes, and their interactions by changing soil physicochemical properties. A few studies have explored how the integrated plant-soil-microbe system responds to elevated N deposition; however, the experimental N loads used in these studies are generally higher than current and future N deposition rates. Thus, these results could generate highly uncertain predictions of the plant-soil-microbe system in response to N deposition because high N addition levels always trigger environmental stress (e.g., soil acidification). We manipulated a long-term experiment, consisting of six N addition levels (0, 1.15, 2.30, 4.60, 9.20, and 13.80 g N m−2 yr−1), in a semiarid grassland in northern China. Our results showed that N addition caused a significant negative relationship between dissolved organic carbon (DOC) and inorganic N, indicating that N addition enhanced C limitation of the soil microbial community and this effect triggered significant decreases microbial respiration. We also demonstrated that N addition significantly decreased soil fungal richness but had no effect on soil bacterial richness. Additionally, aboveground and belowground biomass were significantly increased with N addition, with the highest value at 9.20 N m−2 yr−1 treatment. Relative to control treatment, plant richness was not significantly changed when the N addition rates were lower than 4.6 g N m−2 yr−1 but then significantly decreased. Reduced plant richness and soil microbial respiration were associated with the changes in dissolved inorganic nutrients, soil total nutrients, DOC, as well as soil water content rather than dissolved organic phosphorus and pH. Importantly, aboveground biomass presented a significant negative effect on plant richness, whereas this effect was positive via the pathway of soil microbial respiration. These results show that the current simulated N deposition rates would weaken the linkage between plant productivity and richness but enhance plant-microbe interactions by modifications of soil physicochemical properties other than soil pH, and further impact plant composition. | |||||
22811. 题目: New insights into mechanisms of sunlight-mediated high-temperature accelerated diurnal production-degradation of fluorescent DOM in lake waters | |||||
22812. 题目: Trade-off between new SOC stabilisation from above-ground inputs and priming of native C as determined by soil type and residue placement | |||||
22813. 题目: Arsenic mobilization affected by extracellular polymeric substances (EPS) of the dissimilatory iron reducing bacteria isolated from high arsenic groundwater The factors that control arsenic (As) mobilization by dissimilatory iron reduction (DIR) are complicated. The association between As mobilization and extracellular polymeric substance (EPS) of dissimilatory iron reducing bacteria (DIRB) remained unclear. In this study, three DIRB were isolated from high arsenic groundwater to understand the effects of EPS on As mobilization. In the laboratory settings, strain Klebsiella oxytoca IR-ZA released As into aqueous phase from As-bearing ferrihydrite, but strain Shewanella putrefaciens IAR-S1 and S. xiamenensis IR-S2 re-sequestrated As by forming secondary minerals during ferrihydrite reduction. Characterization of EPS contents with Fourier Transform Infrared Spectroscopy and high-performance liquid chromatography suggested that mannan and succinic acid were the main different EPS contents of the DIRB. The biomineralization processes were tightly regulated by EPS compositions. Mannan secreted by IAR-S1 and IR-S2 promoted while succinic acid secreted by IR-ZA suppressed the biomineralization and As immobilization. Energy-dispersive X-ray Spectroscopy mapping indicated that As in the secondary minerals was wrapped with EPS. X-ray diffraction and room temperature Mössbauer spectroscopy showed these secondary minerals were vivianite and magnetite. The amount of As mobilized into aqueous phase was strongly affected by available anions (H2PO4− and HCO3−). Our results indicated that the EPS of DIRB significantly influenced As mobilization. | |||||
22814. 题目: Effect of gamma-irradiation on complexation of humic substances with divalent calcium ion The effect of gamma-irradiation doses of 0, 10, 100, and 500 kGy at the dose rates of 1 or 0.1 kGy/h on the molecular and chemical properties of humic substances (HS) were investigated using total organic carbon measurements, UV–Vis spectrometry, 13C nuclear magnetic resonance, and acid-base titration. A possible mechanism of the radiolysis on HS was also speculated. The complexation ability of irradiated HS with Ca2+ ions was studied using a Ca ion-selective electrode. The apparent formation constants of the Ca-HS complexes increased as the irradiation dose increased, and this was attributed to the relative increase in the ratio of phenolic –OH to carboxylic groups of HS. The contribution of the phenolic –OH groups to Ca-HS complexes was suppressed at pH 5 owing to its high acid dissociation constants. In addition, the radiation dose rates of 1 and 0.1 kGy/h did not significantly affect the properties of HS and the apparent formation constants of the Ca-HS complexes. | |||||
22815. 题目: Increasing salinization and organic carbon burial rates in seagrass meadows from an anthropogenically-modified coastal lagoon in southern Gulf of Mexico Intertidal ecosystems, such as marshes, mangroves, and seagrasses, contribute to the global carbon storage, helping to regulate atmospheric CO2 concentrations. Organic carbon (Corg) data from seagrass meadows in the Mexican coastline are still scarce, preventing appropriate evaluations of its contribution to mitigate global climate change. Recent temporal changes (≤100 years) of Corg concentrations and burial rates were assessed in 210Pb dated cores from seagrass meadows at Terminos Lagoon, the largest coastal lagoon in the southern Gulf of Mexico. Irrespective of the predominant seagrass species, the cores showed comparable Corg concentrations (0.04–3.9%) and burial rates (2.5–66.7 g m−2 yr−1). Increasing salinization, likely caused by sea level rise, favoured Corg concentrations and burial rates in sediments with Halodule wrightii, while in sediments with Thalassia testudinum only Corg burial rates increased, owing to increasing mass accumulation rates, likely promoted by erosion induced by land use changes, and sea level rise. The mean Corg stock (1 m depth; 130 ± 29 Mg ha−1) was comparable with the global average Corg stock for seagrasses in other tropical areas around the world. Our results suggested that, under the current scenario of land use change and marine transgression, the seagrass meadows in Terminos Lagoon preserve the capacity for Corg accumulation and long-term preservation. However, both factors are also known to reduce seagrass resilience caused by water quality deterioration, thus these ecosystems must be monitored and protected from global change impacts, as part of climate change mitigation efforts. | |||||
22816. 题目: How incorporation depth of corn straw affects straw decomposition rate and C&N release in the wheat-corn cropping system The effects of straw incorporation on soil characters are well known, however, straw incorporation depth impact on corn straw decomposition rate, microbial biomass carbon (MBC) & microbial biomass nitrogen (MBN), soil carbon (C) and nitrogen (N) concentration during straw decomposition have not been documented. A two-year field experiment was carried out in a wheat-corn cropping system to investigate the effects of straw incorporation depth on decomposition rate of corn straw and soil C and N release. The straw incorporation depths were: topsoil 0–10 cm (TI), medium depth 10–20 cm (MI), and deep depth 20–30 cm (DI). The results showed that corn straw decomposition rate was significantly higher in TI by 24.5 % and 16.5 % than in MI and DI treatments from October 2016 to August 2017. The average contents of MBC and MBN during the decomposition period of straw were higher in TI than in MI and DI treatments (P < 0.01). Additionally, the release of N and C from the corn straw was higher in TI, causing a significantly higher average concentration of NO3−–N (P < 0.01) and total organic carbon (P < 0.05) observation in this layer compared with MI and DI. Our results suggest that the corn straw incorporation in topsoil layer of 0–10 cm can decompose faster, and the higher decomposition rate may facilitate the release of C&N from the straw, causing the higher availability of mineral nitrogen and total organic carbon of this layer. | |||||
22817. 题目: Apricot shell- and apple tree-derived biochar affect the fractionation and bioavailability of Zn and Cd as well as the microbial activity in smelter contaminated soil The aim of this study was to elucidate the effects of apricot shell-derived biochar (ASB) and apple tree-derived biochar (ATB) on soil properties, plant growth, microbial communities, enzymatic activities, and Zn and Cd fractionation and phytoavailability in mining soils. Smelter soil contaminated by Zn (1860.0 mg kg−1) and Cd (39.9 mg kg−1) was collected from Fengxian, China, treated with different doses (0 (control), 1, 2.5, 5, and 10% w/w) of both biochars and cultivated by Brassica juncea in a greenhouse pot experiment. The acid-soluble, reducible, oxidizable, and residual fraction and plant tissue concentrations of Zn and Cd were determined. Biochar addition improved plant growth (22.6–29.4%), soil pH (up to 0.94 units), and soil organic matter (up to 4-fold) compared to the control. The ASB and ATB, particularly ATB, reduced the acid-soluble (21–26% for Zn and 15–35% for Cd) and the reducible (9–36% for Zn and 11–19% for Cd) fractions of Zn and Cd and altered these fractions in the organic and residual fractions. Therefore, the biochars decreased the metal concentrations in the roots (36–41% for Zn and 33–37% for Cd) and shoots (25–31% for Zn and 20–29% for Cd), which might be due to the increase in pH, biochar liming effects, and metal sorption by the biochar. The biochars impact on the bacterial community composition was selective. The ASB and ATB decreased the activities of soil β-glucosidase, dehydrogenase, and alkaline phosphatase while increasing the urease activity. The biochars, particularly ATB, can be considered as effective soil amendments for reducing the phytotoxicity of Zn and Cd in contaminated soils, improving plant growth, enhancing the abundance of specific bacterial groups and increasing urease activity; however, more attention should be paid to their negative effects on the activities of β-glucosidase, dehydrogenase, and alkaline phosphatase. | |||||
22818. 题目: Dissolved organic matter adsorption from surface waters by granular composites versus granular activated carbon columns: An applicable approach Many new sorbents have been introduced as an alternative for granular activated carbon (GAC), the most common sorbent for dissolved organic matter (DOM) removal. In the current study, we developed an applicable granular composite based on a flocculant commonly employed for drinking water treatment adsorbed to montmorillonite. DOM adsorption from surface waters, Lake Kinneret and Suwannee River, with low and high specific ultraviolet absorption (SUVA), respectively, by composite and GAC columns, was studied. Adsorption of DOM from Suwannee River was significantly higher by the composite column, in comparison to the GAC column, while an opposite trend was obtained for the adsorption of DOM from Lake Kinneret. In-situ regeneration of the columns with a brine solution was extremely efficient and inefficient for the composite and GAC columns, respectively. Adsorption, of both waters, post-regeneration by the composite column was not compromised, while GAC effectiveness decreased. The opposite trend in DOM adsorption from Suwannee River and Lake Kinneret was explained by the different affinities of the sorbents towards various DOM molecules. Distinguishing between different DOM components adsorbed by GAC and the composite was supported by 13C NMR and direct pyrolysis-GC-MS measurements. Furthermore, we demonstrated that the kinetics and adsorption at the equilibrium of five organic molecules to the composite and GAC can be correlated to their chemical-physical properties. Indeed, combining the properties of both sorbents, by integrating them into a single column, yielded higher DOM removal than by the individual columns. Furthermore, since DOM removal by GAC and by the composite, increases, and decreases with temperature, respectively, the integrated column, mitigates the changes in removal, stabilizing the adsorption performance. Such an integrated filter may minimize additional seasonal and water quality fluctuations. | |||||
22819. 题目: In-situ Synchronous Carbonation and Self-activation of Biochar/Geopolymer Composite Membrane: Enhanced Catalyst for Oxidative Degradation of Tetracycline in Water A new biochar/geopolymer composite membrane (BC/GM) was prepared by an in-situ synchronous carbonation and self-activation process from two sustainable materials. The monolithic geopolymer membrane (GM) served not only as a porous support, achieving good dispersion and retrieve of biochar (BC), but also as a solid base for in-situ activating BC during carbonization of lignin precursor. The obtained BC/GM contained a hierarchically porous structure (exhibiting a bi-modal pore size distribution at 3.54 and 16.53 nm, respectively), having a large specific surface area (37.46 m2/g, 28 times of BC), containing rich functional groups (C-OH, C=O and O=C-O, etc.) and a high degree of graphitization (evidenced by a lower value of ID/IG=0.81) which exhibited a high activity in decomposing H2O2 to generate ·OH radicals for degradation of tetracycline (TC). Nearly 100% of TC (50 mg/L, 100 mL) was removed by 0.15 g BC/GM (1 mL H2O2, pH 5.0, 60 ℃, 5 h). It also showed a good stability and reusability during 5 repeated cycling. EPR, XPS, FTIR and Raman analysis suggested the phenolic-OH, ketone, quinone moieties and defect structures in BC contributed to the generation of ·OH through transferring electrons to H2O2, while the graphitized carbon in BC with porous structure and large surface area provided intimate contact between catalyst and TC molecules that accordingly enhanced the electron conductivity and suppressed the decay of ·OH radicals during redox reaction, which eventually realized the efficient degradation of TC into CO2, H2O, and other inorganic compounds through ring-opening reaction, isomerization, demethylation, deamination, and dehydration reaction. | |||||
22820. 题目: How well can near infrared reflectance spectroscopy (NIRS) measure sediment organic matter in multiple lakes? | |||||
