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22801. 题目: Dynamic evolution of humic acids during anaerobic digestion: Exploring an effective auxiliary agent for heavy metal remediation Information on the dynamic evolution of humic acid (HA) from anaerobic digestate and the potential of HA serving as an effective agent for remedying heavy metals is rather scarce. This study monitored the evolution of the structure and functional groups and metal-binding abilities of HA during chicken manure and corn stover anaerobic digestion (AD) processes. Higher increases in aromatic (41–66%) and oxygen-containing functional groups (37–45%) were observed in HA from the AD of corn stover, resulting in higher metal-binding abilities for Cu(II), Co(II), and Ni(II) than those of chicken manure AD. Moreover, HA extracted from fast (before day 12 for chicken manure and day 16 for corn stover), and slow (day 40) methane production stages performed different complexation capacities for the heavy metals. These results reveal the mechanisms of HA and heavy metal interactions, and confirm the potential of HA extracted from AD process for the remediation of heavy metals. | |||||
22802. 题目: Residue cornstalk derived biochar promotes direct bio-hydrogen production from anaerobic fermentation of cornstalk In this study, an innovative approach was proposed based on the implement of biochar derived from residue cornstalk left after anaerobic bio-hydrogen production (RCA-biochar) to improve direct bio-hydrogen production from anaerobic fermentation of cornstalk. The bio-hydrogen production potential and maximum bio-hydrogen production rate increased from 156.2 to 286.1 mL H2/g substrate and 3.5 to 5.7 mL H2/g substrate/h, respectively, following the added RCA-biochar increased from 2.5 to 15.0 g/L. Cornstalk chemical component analysis showed the cellulose and hemicellulose content decreased by 17.9–33.7% and 14.4–25.2%, and lignin content increased by 20.3–42.8%, respectively, after 96 h anaerobic fermentation with RCA-biochar 2.5–15.0 g/L. Further analyses revealed that RCA-biochar not only provided more specific surface area for hydrogen-producing bacteria attachment, but also promoted the cellulolytic enzyme activity, thereby resulted in increased substrate conversion to bio-hydrogen. The findings obtained in this study may provide supports for effective and sustainable lignocellulosic bio-hydrogen production in the future. | |||||
22803. 题目: Effects of vegetation type, season, and soil properties on soil microbial community in subtropical forests The diversity and composition of soil microbial community in forests are affected by vegetation type, season, and soil properties, but the relative importance of these factors on the diversity and composition of microbial community is poorly understood. In this study, high-throughput sequencing was used to assess the soil prokaryote (16S rRNA) and fungal (ITS rRNA) communities of five vegetation types (evergreen broad-leaved forest [EBL], deciduous broad-leaved forest, mixed coniferous–broad-leaved forest, coniferous forest [CF], and secondary shrubland [SS]) for four seasons in a secondary subtropical forest in Eastern China. Soil physicochemical properties and plant diversity were also surveyed for each vegetation type. Vegetation type, season, and their interaction significantly affected the Shannon diversity indexes of soil prokaryotes. The Shannon index of soil fungi was affected by vegetation type. The soil prokaryote and fungal compositions of the five vegetation types were significantly different. The prokaryote compositions of EBL, CF, and SS significantly changed in four seasons, but only the fungal composition of SS changed with the seasons. Variation partition showed that vegetation type and season individually explain 25% and 29% of the variance in prokaryote composition and 19% and 1% of the variance in fungal composition, respectively. Prokaryote diversity and composition were significantly driven by soil pH and organic carbon and fungal diversity and composition were significantly driven by soil pH and electrical conductivity when controlling the effects of vegetation types and seasons. | |||||
22804. 题目: Biochar Aging: Mechanisms, Physicochemical Changes, Assessment, And Implications for Field Applications | |||||
22805. 题目: Cr(VI) Formation via Oxyhalide-Induced Oxidative Dissolution of Chromium Oxide/Hydroxide in Aqueous and Frozen Solution | |||||
22806. 题目: Fingerprint of plant life in the Atacama Desert – insights from n-alkane analyses Although the Atacama is the oldest and most continuous dry desert on Earth, organic matter (OM) is ubiquitous in its surface sediments. Today, vegetation growth is restricted to the Coastal Cordillera and the Andean foothills, which are predominantly supplied by fog or rainfall. The sources of OM in topsoils of hyperarid regions and deep sediments remain an open question; therefore, we hypothesized that desert plants exhibit specific n-alkane compositions that can be traced in adjacent topsoils and assessed possible OM sources and formation processes in hyperarid regions and soil depths of desert. We determined the n-alkane signatures of plants (n=28), of soil OM in their vicinity, of hyperarid surface sediments (n=82), and of four depth profiles (up to 200 cm). We found that n-alkane distributions in fog-fed plants were dominated in order by nC31, nC29, nC33, and nC27 alkanes, while rain-fed plants were dominated by nC29 and nC31 alkanes. When the ratio of nC27+nC33/nC29+nC31 was applied as a fog-to-rain n-alkane ratio, the data in surface soils and sediments below 1200 m a.s.l. (in the west of the desert) indicated fog-influenced formation of organics, while all soils and sediments formed higher than 1200 m a.s.l. (in the center and east of the desert) archived n-alkanes from plants fed by rain. Surprisingly, 75–98% of the desert's OM was found in deep sediments, even under recent vegetation cover. Hence, our findings indicate that currently vegetation-free hyperarid regions of the Atacama Desert varied in size depending on climate change. | |||||
22807. 题目: Aggregation and stability of sulfate-modified polystyrene nanoplastics in synthetic and natural waters Nanoplastics (NPs) are becoming emerging pollutants of global concern. Understanding the environmental behavior of NPs is crucial for their environmental and human risk assessment. In this study, the aggregation and stability of polystyrene (PS) NPs were investigated under different hydrochemical conditions such as pH, salt type (NaCl, CaCl2, Na2SO4), ionic strength (IS), and natural organic matter (NOM). The critical coagulation concentrations of PS NPs were determined to be 158.7 mM NaCl, 12.2 mM CaCl2, and 80.0 mM Na2SO4. Ca2+ was more effective in destabilizing PS NPs, compared to Na+, owing to its stronger charge screening effect. In the presence of monovalent ions, NOM reduced aggregation through steric repulsion, whereas in the case of divalent ions, NOM induced aggregation through cation bridging. Initial and long-term stability studies demonstrated that, in waters with high IS and NOM content, NOM was the most significant factor affecting NPs aggregation. PS NPs would be highly suspended in all freshwaters, and even in wastewater, whereas they would aggregate rapidly and deposit in seawater. Finally, a statistical model was established to evaluate the hydrodynamic diameter of NPs in different waters. The results indicated the stability of PS NPs in natural aquatic environments and their potential for long-term transport. | |||||
22808. 题目: Combined biochar and soda residues increases maize yields and decreases grain Cd/Pb in a highly Cd/Pb-polluted acid Udults soil Excessive heavy metal (HM) in soil limit crop yields and reduce quality of crops and soil. In this study, a 3-year field experiment was conducted to verify the effects of different amendment treatments on the accumulation and distribution of cadmium/lead (Cd/Pb) on maize aboveground parts and the availability of Cd/Pb in Udults soil. The treatments were CK, biochar at 5, 10, 20, 30 t ha−1 (B1–B4), soda residues at 3 t ha−1 (M) and biochar & soda residues (10 t ha−1 + 3 t ha−1; B2M). The results show that the greater the applied biochar dose, the longer lasting the mediating effect; however, the B2M treatment was the most effective and had the longest-lasting effects. Compared to CK, the B2M treatment significantly increased soil pH and total organic carbon levels by 0.68–1.44 pH units and 16.2 %–30.3 %, respectively, and reduced available Cd/Pb by 52.4 %–68.6 % and 28.3 %–40.8 %, respectively. Additionally, B2M also increased the maize grain yield by 7985.2–10,728.9 kg ha−1 and decreased the Cd/Pb contents of maize grains by 0.16–0.21 mg kg−1 (Cd) and 0.05–0.51 mg kg−1 (Pb) over the 3-year period. The Cd/Pb contents in maize grain were lower than the feed additive standard (GB 13078−2017), indicating that this product can be used as animal feed. Soil pH was the most important factor to control Cd/Pb accumulation, while the Cd was also influenced by biochar physicochemical properties such as specific surface area, aromatic structures and oxygen-containing functional groups. A cost analysis for this field experiment revealed that applying combined biochar and soda residues to polluted soil had an economic benefit whereas the application of biochar alone did not. | |||||
22809. 题目: Influence of 9 years Permanent Raised Beds and Contour Furrowing on Soil Health in Conservation Agriculture Based Systems in Tigray Region, Ethiopia Conservation agriculture (CA) systems represent a set of three soil management principles that include minimal soil disturbance, permanent soil cover and crop rotations whereas the CA‐based systems in this study add the bed and furrow tillage structures as integral elements of CA. Studies on the effects of long‐term CA‐based systems on soil health and crop productivity are rare globally, particularly in Ethiopia. This study aimed at investigating the long‐term (2005‐2013) influence of CA‐based systems on soil health and crop productivity in northern Ethiopia. The treatments include two types of CA‐based systems (permanent raised bed PRB and contour furrowing CF) and conventional tillage (CT) arranged in a randomized complete block design. Soil samples were collected at 0‐10 cm soil depth to assess soil health. Piecewise structural equation modeling (PSEM) was used to analyze linkages between management practices, soil health and crop productivity. Arbuscular mycorrhizal fungi spore abundance and root colonization was higher in PRB followed by CF compared to CT (P < 0.05). Significantly different soil N of 1.4 and 0.9 g kg‐1 and available P of 6.7 and 4.1 ppm were recorded for PRB and CT, respectively. Higher straw and grain yield of 12 and 4.3, 10 and 3.5, 8 and 2.8 t ha‐1 were recorded for PRB, CF and CT, respectively. Outputs of the PSEM highlighted two pathways in which CA‐based systems contributed to improved productivity: (1) via higher density of bacteria and improved hydraulic conductivity, and (2) via higher density of fungi and increase soil organic carbon content in the topsoil. The study concludes that CA‐based systems have the potential to improve crop productivity through improved soil health. This article is protected by copyright. All rights reserved. | |||||
22810. 题目: Acceptable soil baseline levels in Taltal, Chile, and in Tampere, Finland Soil geochemical baselines of potentially toxic elements were studied in two cities: Tampere in Finland and Taltal in Chile. Soil samples were sieved to the <2 mm grain-size fraction and the concentrations of As, Cd, Co, Cr, Cu, Hg, Ni, Pb, Sb, V and Zn were measured after aqua regia extraction. The upper limit of baseline variation was defined for the topsoils of Tampere and for soil samples from various lithological units in Taltal. Arsenic was the potentially toxic element of most concern in both towns. In both cases, arsenic concentrations were mostly geogenic. Anthropogenic activities related to the long mining history had caused elevated As concentrations in the topsoil samples in parts of Taltal city and soils surrounding abandoned mining wastes. In the case of this study, the geochemical baseline was useful to show the pollution level of As. Vanadium concentrations were also higher than the global average values in soils of Taltal commune. Heatmap plots based on compositional data analysis revealed that the abundance of mica minerals and soil organic matter controlled the distribution of most of the studied elements in Tampere, while the clustering of metals in Taltal was probably related to either abandoned mining sites or active mining operations. Regional baseline values should be used for the assessment of soil contamination with these elements in both cities. | |||||
22811. 题目: Evidence of recent flood deposits within a distal shelf depocenter and implications for terrestrial carbon preservation in non-deltaic shelf settings | |||||
22812. 题目: The stoichiometric C-Fe ratio regulates glucose mineralization and stabilization via microbial processes The association of soil organic matter (SOM) with iron (Fe) oxides by adsorption and/or co-precipitation contributes to long term C stabilization in soil. While there is an understanding of the relationship between soil carbon (C) and the biogeochemical cycling of Fe, a lack of information exists on the role of Fe oxides on the accumulation of C in paddy soils. This study aimed to assess the role of Fe (oxyhydr)oxides on mineralization and stabilization processes following amendment of paddy soil with a labile C substrate (99 atom % 13C-glucose). The study utilized 4 paddy soils with a total Fe concentration ranging from 13.7 to 55.8 g kg−1. In soils with 42.7 and 55.8 g kg−1 Fe, the addition of glucose resulted in an Fe bound organic C: Fe molar ratio (C:Fe molar ratio) ≥6, suggesting the formation of Fe-OM complexes mainly via co-precipitation. The highest portion of 13C (13.8%) protected in Fe-OM complexes was found in soil containing 55.8 g kg−1 of Fe. The stabilization of the added labile C substrate was shown, using random forest analysis, to be controlled by the C: Fe molar ratio, while substrate mineralization was regulated by the core genera Sphingomonas and Devosa (r-strategists) (affiliated to Proteobacteria) and C:N ratio. Substrate mineralization was 47% lower in soil containing 55.8 g Fe kg−1 compared to 13.7 g Fe kg−1, with a concomitant reduction in SOM priming of 37%. This reduction in substrate mineralization and the priming effect was likely due to lower C substrate availability via the formation of Fe-OM complexes, thereby protecting the C from mineralization. In conclusion, the Fe concentration in paddy soils plays a central role in the abiotic stabilization of 'new' C through the formation of Fe-OM complexes via co-precipitation, thereby limiting the availability of this C substrate for microbial mineralization, and at the same time modulating the microbial community structure. | |||||
22813. 题目: Detailed composition evolution of food waste in an intermittent self-agitation anaerobic digestion baffled reactor This study used an intermittent self-agitation anaerobic baffled reactor (SA-ABR) to treat food waste. The organic matter and detailed composition evolution were analyzed under continuous operation. The gas production rate was 2.43 ± 0.18 L-Gas/d/L-Re, and the biogas conversion was 0.94 L-Gas/g-TS. The effluent concentration of total chemical oxygen demand (COD) was 22.5 ± 2.44 g/L, and the removal rate of soluble COD was always over 97%. In this study, the removal rates of carbohydrate, protein, and lipids in the SA-ABR treatment were 95%, 60%, and 85%, respectively, and the concentrations were 0.11 g/L, 0.32 g/L, and 0.33 g/L, respectively. The conversion of soluble organic matter was much higher than that of insoluble substrates. The concentration of soluble pollutants was significantly lower than that of pollutants in suspended matter. The treatment of organic matter in the first half of the SA-ABR was 85–100% that of the entire reactor. | |||||
22814. 题目: Effects of biowaste-derived biochar on the electron transport efficiency during anaerobic acid orange 7 removal In this study, different biochar (based on different pyrolytic temperatures and iron dosage) were prepared, characterized and used as individual additives for promoting acid orange 7 (AO7) anaerobic digestion. After X-ray diffraction (XRD), fourier transform infrared spectrometer (FTIR) characterization, 600 °C was proved to be the preferred temperature. Subsequently, biochar pyrolyzed at 600 °C with different iron dosage were added into five anaerobic reactors. Results showed that COD removal efficiency reached the maximum value (88.5%) with the presence of 600-1 biochar, which was 19.0% higher than control reactor (without biochar added). Further analysis indicated that more functional groups were found in 600-1 biochar could effectively improve the electron accepting capacities (EAC) and electron donating capacities (EDC). Combined with the enrichment of exoelectrogens related to syntrophic metabolism, it can be concluded that the addition of biochar could effectively improve the electron transfer efficiency which would be beneficial for AO7 removal. | |||||
22815. 题目: Effect of water availability on induced cyanobacterial biocrust development Cyanobacteria inoculation has recently become an innovative biotechnological tool for restoring degraded arid soils. A major challenge for researchers, however, is the search for suitable species able to cope with water stress under field conditions. The aim of this study was to test the effect of water availability on induced biocrust growth in three different degraded soils from semiarid areas of Almeria (Spain). Three native N-fixing cyanobacterial strains, Nostoc commune, Scytonema hyalinum and Tolypothrix distorta, were inoculated on soil samples from the study areas, individually and as a consortium. Two different irrigation treatments simulating the water availability in the selected areas, in a dry year (180 mm/year) and a wet year (380 mm/year), were applied for three months under laboratory conditions. Cyanobacteria cover, chlorophyll a spectral absorption (Chla spectral absorption), soil organic carbon (SOC) and total exopolysaccharide (EPS) gains were measured as indicators of biocrust development. Cyanobacteria crust cover, SOC and EPS gains were higher in inoculated soils than in uninoculated soils. Even though the hydration regime had a generally significant effect on cyanobacteria cover, Chla spectral absorption and EPS, similar biocrust development and improvement in edaphic conditions were observed under both hydration regimes for all treatments. Of the candidate inoculants, N. commune showed remarkably higher performance under dry conditions than the rest, providing evidence of high potential for growing under water-limited conditions and being a good candidate inoculant for restoration of arid degraded areas. | |||||
22816. 题目: Photochemistry of dissolved organic matter extracted from coastal seawater: Excited triplet-states and contents of phenolic moieties Coastal seawater constitutes an important ecosystem receiving inputs of organic micropollutants (OMPs) such as sulfa antibiotics from land-based sources or mariculture activities. It is necessary to investigate photodegradation of OMPs in coastal seawaters for assessing their environmental fate and risks. However, effects of coastal seawater dissolved organic matter (S-DOM) on OMPs photodegradation are largely unknown, given that chemical compositions of S-DOM are different from those of freshwater DOM. Herein, photochemical characteristics of S-DOM extracted from Dalian coastal seawaters were investigated by simulating photochemical experiment adopting sulfachloropyridazine as a case. Results show that S-DOM accelerates the photodegradation mainly through excited triplet-state DOM (3DOM*) with an apparent rate constant (4.43 × 108 M−1 s−1) ten folds of that of freshwater DOM, which is mainly due to much lower phenol contents detected in the S-DOM (0.022 mg-Gallic acid mg-C−1). The S-DOM impacted by mariculture can photogenerate more high-energy 3DOM* than those less impacted by mariculture, further contributing to the high 3DOM* reactivity. The study shows that to accurately predict photolytic persistence of OMPs in field water bodies, it is of significance to determine the second-order reaction rate constants between 3DOM* and target OMPs using DOM extracted from relevant water bodies. | |||||
22817. 题目: Structural changes in model compounds of sludge extracellular polymeric substances caused by exposure to free nitrous acid Previous studies demonstrate that free nitrous acid (FNA i.e. HNO2) detaches sewer biofilms, breaks down flocs of waste activated sludge (WAS) and enhances biogas production from WAS. This suggests possible interactions of FNA with organic extracellular polymeric substances (EPS) that bind the cells into biofilms or sludge flocs. This study evaluates the chemical interactions and reaction mechanisms between FNA and molecules representative of key EPS in biofilm and sludge flocs. Molecules chosen to represent components found in the extracellular polymeric matrix were treated with FNA at 6.09 mgN/L (NO2− = 250 mgN/L, pH = 5.0 ± 0.2, T = 22 °C) for 24 hours (conditions typically used in applications) so as to consider the hypothesized chemical interactions and the consequent reaction pathways. A number of analytical techniques were employed to measure the molecular changes in the EPS molecules including; proton (1H) nuclear magnetic resonance spectroscopy (NMR), electrospray ionisation mass spectrometry (ESI-MS) and gel permeation chromatography (GPC). The results demonstrated that FNA broke down a range of large EPS molecules including carbohydrates, protein and lipids to smaller molecules. Two mechanistic pathways have been proposed including electrophilic substitution, whereby the nitrosium ion (NO+) was the reactive electrophile, and oxidative radical reactions, through which the nitrogen radicals (NO2, NO) and reactive nitrogen intermediates (RNIs) (e.g. N2O3 and N2O4) formed from the decomposition of FNA became part of the reaction products. Larger, more complex organic molecules such as humic acid, required higher concentrations of FNA (6.09 mgN/L or greater) to cause molecular breakdown, whereas smaller molecules, such as calcium alginate, was broken down at lower concentrations (3.04 mgN/L). The study contributes to the understanding of the fundamental mechanisms behind the application of FNA for biofilm control and flocular sludge disintegration. | |||||
22818. 题目: A nine-year study on the effects of tillage on net annual global warming potential in double rice-cropping systems in Southern China It is important to look for management practices which can effectively reduce greenhouse gas emissions (GHGs) in agricultural systems. A field experiment was conducted during 2005−2014 to assess tillage impacts on net global warming potential (NGWP) including estimation of soil organic carbon (SOC) change and indirect emissions (IE) on a double rice system in Southern China. Three treatments used in this study were no tillage with residue retention (NT), rotary tillage with residue retention (RT), and plow tillage with residue incorporation (PT). In respect of SOC sequestration, annual mean rates (0–20 cm) were not significantly different between tillage treatments averaging 2.89 MgC ha−1 yr−1 during 2005−2014. Two-year (2013–2014) measurement of GHGs showed NT tended to significantly decrease annual CH4, but increase N2O emissions in the paddy soil. IE from farm inputs was found lowest in the NT treatment due to no additional tillage. NT and RT practices had better double rice yields by 0.8 % and 3.4 % relative to the PT without significant difference over the nine-year period. Lowest mean NGWP and NGHGI was found under the NT among all treatments in this study. The results suggested GHG mitigation and agricultural economic viability can be achieved by NT practice in double rice cropping systems. Meanwhile, the long-term effects of NT practice on rice yield and SOC storage should also be considered in future studies. | |||||
22819. 题目: Efficient nitrate removal by Pseudomonas mendocina GL6 immobilized on biochar The performance of nitrate removal by Pseudomonas mendocina GL6 cells immobilized on bamboo biochar was investigated. The results showed that immobilized bacterial cells performed better nitrate removal than the free bacterial cells, and the nitrate removal rate increased from 6.51 mg/(L·h) of free cells to 8.34 mg/(L·h) of immobilized cells. The nitrate removal of immobilized bacterial cells fitted well to the zero-order kinetics model. Moreover, bath experiments showed that immobilized bacterial cells displayed more nitrate removal capacity under different conditions than free bacterial cells due to the protection of biochar carrier. The subsequent mechanistic study suggested that biochar promoted the expression level of denitrification functional genes (napA and nirK) and electron transfer genes involved in denitrification (napB and napC), which resulted in the increase of nitrate removal efficiency. Thus, biochar-immobilized P. mendocina GL6 has much potential to remove nitrate from wastewater via aerobic denitrification. | |||||
22820. 题目: Soil microbial biomass and composition from urban landscapes in a semiarid climate Soil microbial communities have been used as indicators of changes in soil health agroecosystems. However, few studies have evaluated soil health under turfgrass systems especially in semiarid climates. Our study determined whether microbial biomass and composition in residential soils were controlled by home age along a turfgrass chronosequence and evaluated effects of turfgrass management in structuring soil microbial communities. Soil samples were obtained from nine locations within each home age category: oldest (1950–1970), middle (1971–1990), newer (1991–2010), and newest (2011–present) in summer 2018 and 2019. Soil microbial biomass and composition were assessed using chloroform fumigation extraction method (CFEM) and ester-linked fatty acid methyl ester (EL-FAME) analysis. Soil microbial biomass carbon (MBC) and nitrogen (MBN) were 46–52% and 65–75% higher in oldest homes when compared to newest homes, respectively. Neither total FAMEs nor fungal FAME abundance differed for home age categories, but bacterial FAME abundance increased with home age. Non-parametric analysis determined no microbial abundance differences with management practices or turfgrass species. Pearson correlations indicated soil organic matter and silt content most consistently altered the microbial community. Soil microbial communities within semiarid, urban environments shifted from high fungal to bacterial dominated as landscapes matured, potentially due to long-term effects of irrigation, fertilization, and pesticide use. Our results indicate time after establishment was more important to development of soil microbial communities in semiarid, perennial turfgrass systems than subtle differences in management, suggesting soil health and resource conservation goals in this setting may be achievable with relatively low levels of management over time. | |||||
