61. 题目: Influence of pyrolysis temperature on sludge biochar: the ecological risk assessment of heavy metals and the adsorption of Cd(II)
Pyrolysis of sludge to biochar can not only reduce the sludge volume, toxic organic compound, and pathogens, but also be applied as effective adsorbents. However, the immobilization of heavy metals in the sludge and the properties of the biochar greatly rely on the pyrolysis temperature. In this paper, municipal sludge biochar (SBC) was prepared from 400 to 1000 °C. Pyrolysis immobilized heavy metals in sludge and the potential ecological risk of heavy metals significantly decreased to low level at temperature above 500 °C. At 700 °C, the adsorption capacity of Cd(II) reached a maximum (120.24 mg·g−1). The Cd(II) adsorption fitted the Pseudo-second-order model, indicating the existence of chemical adsorption. The adsorption capacity increased along with the initial pH and slowed down after pH reached 5.5. The existence of coexisting cations (Ca2+ and Na+) and anions (SO42− and NO3−) displayed different degree of inhibitory action on Cd(II) adsorption. The SEM, XRD, FTIR, and XPS analysis of sludge biochar before and after adsorption revealed that there were CdCO3, CdSO4, Cd2SiO4, Cd3(PO4)2, and Cd9(PO4)6 appearing on the surface of sludge biochar, suggesting that the adsorption of Cd(II) by SBC included co-precipitation, ion exchange, coordination with π electrons, and complexation. It was confirmed that different properties formed by pyrolysis temperature made a difference in adsorption mechanism of sludge biochar.
62. 题目: Removal of cadmium in aqueous solutions using a ball milling–assisted one-pot pyrolyzed iron-biochar composite derived from cotton husk
A novel iron-biochar composite adsorbent was produced via ball milling–assisted one-pot pyrolyzed BM-nZVI-BC 800. Characterization proved that nano zero valent iron was successfully embedded in the newly produced biochar, and the nZVI payload was higher than that of traditional one-pot pyrolyzed methods. BM-nZVI-BC 800 provided a high adsorption performance of cadmium reaching 96.40 mg·g−1 during batch testing. Alkaline conditions were beneficial for cadmium removal of BM-nZVI-BC 800. The pseudo-second-order kinetic model and Langmuir isotherm fitted better, demonstrating that the Cd adsorption on the BM-nZVI-BC 800 was a chemical and surface process. The intraparticle diffusion controlled the adsorption of BM-nZVI-BC 800. The physisorption dominated by high specific surface area and mesoporous structure was the primary mechanism in the removal of cadmium, though electrostatic attraction and complexation also played a secondary role in cadmium adsorption. Compared to adsorbents prepared by more traditional methods, the efficiencies of the ball milling–assisted one-pot pyrolyzed method appears superior.
63. 题目: Continuous inactivation of human adenoviruses in water by a novel g-C3N4/WO3/biochar memory photocatalyst under light-dark cycles
Viruses transmitted by water have raised considerable concerns for public health. A novel memory photocatalyst of g-C3N4/WO3/biochar was successfully developed for effective inactivation of human adenoviruses (HAdVs) in water, in which WO3 as an electron-storage reservoir and biochar as an electron shuttle is employed to synergistically improve photocatalytic activity of g-C3N4. The tertiary composite exhibited continuous photocatalytic performance for HAdVs inactivation without regrowth in water under light-dark cycles, i.e., ~3.9-log inactivation under 6-h visible light irradiation and an additional ~1.1-log inactivation under the following 6-h dark. The enhanced virucidal mechanism was attributed to the heterojunction formation and especially the electron-transfer pathway switching via biochar incorporation, contributing to electron transfer and storage in the light phase and then electron release in the dark phase, along with obviously increased generation of the virus-killing •OH radicals under light-dark cycles.
64. 题目: The formation of refractory dissolved organic nitrogen from free amino acids in the ocean
65. 题目: Pyrolysis of hydrothermally dewatering sewage sludge: Highly efficient peroxydisulfate activation of derived biochar to degrade diclofenac
The resource utilization of sewage sludge can solve its disposal issue essentially. Meanwhile the removal of diclofenac (DCF) in wastewater is an emerging environmental problem. In this study, a novel strategy of sludge utilizing via hydrothermal - peroxydisulfate (PDS) dewatering coupled pyrolysis process was proposed. The obtained sludge-derived biochar (HSC) could be as candidate to activate PDS to degrade DCF. Results indicated that exceed 90% of DCF was eliminated within 30 min in HSC-PDS/DCF ternary system under the optimized condition (0.6 mmol/L PDS and 0.5 mg/L HSC, without temperature and pH pre-adjusting). The inner mechanism of HSC-PDS/DCF system was revealed as follows: (1) Major: CO in quinones and ketone structure in HSC accelerated the degradation of DCF via non-radical pathway (electron transfer and 1O2). (2) Minor: Graphitic N structure accelerated the electron transfer and O2•- originated from defective sites involved into the redox. Several by-products were identified and two tentative degradation pathways of DCF (eg. dechlorination and C–N cleavage) were proposed.
66. 题目: Spatiotemporal pattern and biodegradation process of amino acids in the large shallow eutrophic lake Taihu, China
Organic matter (OM) and nutrient inputs generated by human activities promote the development of eutrophication. Amino acids (AAs) are an integral part of OM, and studying their patterns will provide new insights into organic matter dynamics in lakes. Four seasonal field campaigns in eutrophic Lake Taihu and a 14-day phytoplankton degradation experiment were carried out to determine the variability and bioavailability of amino acids. The quality and quantity of AAs varied among different seasons and lake types. The concentrations of particulate (PAA) and dissolved (DAA) AA were 14.67 ± 13.25 μM (carbon- and nitrogen-normalized PAA yields: PAA-C%, 23.8 ± 13.5%; PAA-N%, 22.8 ± 2.1%) and 2.95 ± 1.05 μM (carbon- and nitrogen-normalized DAA yields: DAA-C%, 3.7 ± 1.1%; DAA-N%, 12.6 ± 11.2%) in Lake Taihu, respectively. PAA and DAA showed high mean values in the algal-dominated northern area in summer. Glutamic acid (Glu), alanine (Ala), aspartic acid (Asp) and glycine (Gly) contributed to nearly 50% of PAA, while Gly, accounting for 17–24%, was the main component of DAA. During a 14-day phytoplankton degradation period, 98% of Chl a, 63% of POC and 92% of PAA were removed in the dark treatment, and a more obvious downward trend was recorded than in the light treatment. Principal component analysis of the indices of PAA indicated that Glu, arginine (Arg) and histidine (His) were dominant on day 0, while Gly and lysine (Lys) were dominant on day 14. There were notable serine + threonine (Ser + Thr [mol%]) and aspartic acid/glycine ratio (Asp/Gly [mol%]) end-member divisions among different organic matter sources. DAA had higher Ser + Thr [mol%] and lower Asp/Gly [mol%] values than PAA. The amino acid degradation index (DI) of PAA and DAA was 0.97 ± 0.28 and − 1.04 ± 0.43, respectively. The fresh DAA from the algae degradation incubation also had DI values similar to those of field DAA in the northern algae–dominated lake region. Amino acid parameters (AA-C%, DI values, Ser + Thr [mol%] and Asp/Gly [mol%]) were calculated to indicate the source, freshness and bioavailability of organic matter in eutrophic shallow Lake Taihu.
67. 题目: Contribution of exogenous humic substances to phosphorus availability in soil-plant ecosystem: A review
Phosphorus (P) is one of the largest nutrients limiting crop productivity. Meanwhile, P deficiency is a common phenomenon in agricultural soils around the world. Humic substances, as macromolecular polymer, accelerate and strengthen process which transforms P into bio-available forms via a range of chemical reactions and biological interactions. There is now an urgent need to comprehend the work carried out on the interaction among humic substances, soil and plant to better understand their role in the transformation and promotion of soil bioavailable P for plant growth. Herein, we discuss the factors and mechanisms of humic substances influencing P cycling in soil-plant systems, which focus on their contribution to soil P mobilization and plant P acquisition. This review covers how humic substances influence the mobilization and transformation of P in soils, including release of P from residues, and competitive adsorption of P and humic acid or fulvic acid to metallic minerals, as well as exchange with P adsorbed by humic substances. It then discusses a range of contributions to plant available P acquisition such as the release of organic acids from roots caused by humic substances, and promoting the solubilize and/or hydrolyze phosphate by plant and their associated microbes. Notably, we also discuss the challenges of artificial humic substances influencing P cycling in soil-plant systems, which may alleviate the global deficit of soil P resources. Overall, humic substances have become promising for sustainable agriculture over time and have great potential to meet specific soil-plant systems.
68. 题目: An iron-biochar composite from co-pyrolysis of incinerated sewage sludge ash and peanut shell for arsenic removal: Role of silica
Modification of biochar by low-cost iron sources has gained increasing attention to improve pollutants removal performance and reduce production costs compared to conventional chemical modifications. While such iron sources generally have complex compositions, their effects on properties of the iron-biochar composite are not well investigated. This study produced an iron-biochar (RBC) composite from co-pyrolysis of incinerated sewage sludge ash (ISSA) and peanut shell, and examined the role of silica with widespread existence in ISSA and other low-cost iron sources on properties of the iron-biochar composite relevant to As(III)/As(V) removal. Silica was found to react with iron during the pyrolysis process at 850 °C and formed iron silicon at the expense of producing zero valent iron (ZVI) and Fe3O4 which resulted in an removal inferior efficacy for As(III) and As(V) compared to an iron-biochar (FBC) made from pure Fe2O3 and peanut shell. Moreover, a high leaching of reactive silica from RBC was observed which affected the formation of corrosion products of ZVI and competed with arsenic for active adsorption sites. Irrespective of these, RBC still exhibited a maximum adsorption capacity of 17.44 and 57.56 mg/g towards As(III) and As(V) respectively at pH 3.0. Overall, this study provides an interesting insight into upcycling ISSA into useful media for sorptive removal of arsenic from aqueous solutions.
69. 题目: Response of bacterial communities and function to dissolved organic matters in groundwater contaminated by landfill leachate
The migration and transformation of dissolved organic matter (DOM) caused by landfill leachate leakage affected the phylogenetic development of bacterial communities in groundwater around the landfill. Previous studies mainly focused on the hydrochemical properties of DOM in groundwater contaminated by landfill leachate and the relationships between groundwater quality parameters and bacterial communities. However, the changes in DOM components and bacterial communities caused by landfill leachate leakage and their correlations remained unclear. In this work, we analyzed the evolution characteristics of DOM and identified the bacterial communities and their corresponding functions in groundwater around the landfill. The results showed that DOM content in groundwater increased after the diffusion of landfill leachate to groundwater. Significant differences in characteristics between DOM components were presented at different locations in the landfill leachate plume due to the physical dilution and bacterial degradation of DOM. One of the obvious manifestations was the tendency of humic acid-like substances to accumulate at downstream points. Samples from the contaminated aquifer had higher diversity and abundance of bacterial communities than those in the uncontaminated aquifer. Anaerobic or facultative anaerobic bacteria played predominant roles in contaminated groundwater, due to the input of organic matter, nitrate, and ammonia nitrogen. Redundancy analysis indicated that the content of fulvic acid-like DOM had a conspicuous impact on the composition of bacterial communities in the polluted groundwater. Vogesella were the dominant bacteria at the genus level in groundwater around the landfill. Furthermore, Vogesella were significant for microbial utilization and played an important role in the production of fulvic acid-like DOM. These results indicated that landfill leachate pollution posed a potential threat to the structure and function of bacterial communities in groundwater, and provided a basis for exploring the interaction between DOM composition and bacterial communities in groundwater plume contaminated by landfill leachate.
70. 题目: Vegetation-promoted soil structure inhibits hydrologic landslide triggering and alters carbon fluxes
71. 题目: Biochar application enhanced rice biomass production and lodging resistance via promoting co-deposition of silica with hemicellulose and lignin
Biochar, an environmentally friendly soil amendment, is created via a series of thermochemical processes from carbon-rich organic matter. The biochar addition enhances soil characteristics dramatically and increases crop growth and yields. However, the mechanism by which biochar improves plant lodging resistance, which is heavily influenced by cell walls, remains unknown. Three rice cultivars were grown in an experimental field provided with four concentrations of biochar (10, 20, 30, 40 t ha−1). The biochar application enhanced biomass production and lodging resistance in all three cultivars by up to 29 % and 22 %, respectively, with the largest improvement at a biochar application rate of 30 t ha−1. Biochar application significantly enhanced stem cell wall-related characteristics, with an increase in stem breaking force, wall thickness, and plumpness of 52 %, 32 %, and 21 %, respectively, which are suggested to be major contributors to enhanced lodging resistance and biomass yield. Notably, cell wall composition and silica content analysis indicated a significant increase in hemicellulose, lignin, and silica content in biochar-treated samples up to 36 %, 13 %, and 58 %, respectively, when compared to plants not treated with biochar. Integrative analysis suggested that silica, hemicellulose, and lignin were co-deposited in cell walls, which influenced biomass production and lodging resistance. Furthermore, the transcriptome profile revealed that biochar application increased the expression of genes involved in biomass production, cell wall formation, and silica deposition. This study suggests that biochar application might improve both biomass production and lodging resistance by promoting the co-deposition of silicon with hemicellulose and lignin in cell walls.
72. 题目: An isotope, elemental, and n-alkane baseline for organic matter sources in sediments of high-altitude lakes in the Uinta Mountains, Utah, USA
This research provides a critical baseline for chemical and macromolecular characteristics of organic matter (OM) sources in high-elevation lake sediments. Such studies are essential for accurate paleoenvironmental interpretation of organic matter characteristics, particularly in mountain regions where steep environmental gradients lead to spatially variable OM inputs among lakes. We analyzed the carbon- and nitrogen-isotope compositions (δ13CTOC, δ15NTN), and total organic carbon to total nitrogen atomic ratios (TOC:TN), of whole tissues of modern vegetation, lichen and algae from Uinta Mountain lakes, along with the abundances and carbon- and hydrogen-isotope compositions of n-alkanes (δ13Cn-alkane, δ2Hn-alkane). TOC:TN can be used to distinguish between aquatic and terrestrial sources, but the differentiating values are higher in the Uinta Mountains than in low-elevation regions. Chain lengths of n-alkanes are more useful than n-alkane isotope compositions for differentiating between terrestrial and semi-aquatic sources in the Uinta Mountains. The ratio of n-alkanes C23 to C27 in mountain lake sediment OM can be used to detect inputs from coniferous krummholz trees and may serve as a proxy for treeline position. We used the isotope data from n-alkanes to calculate the carbon-isotope fractionation between atmospheric carbon dioxide and the n-alkane C23 (ɛbulk), and the hydrogen-isotope fractionation between source water and the n-alkane C25 (ɛwater). These fractionation factors, and the isotope compositions of n-alkanes extracted from lake sediments, suggest that the δ13C of atmospheric CO2 was − 7.0 ± 2‰ and the δ2H of precipitation was − 133 ± 7‰ at ~ 1400 CE in this region. These calculations demonstrate potential applications of our results for obtaining additional paleoclimatic information from paleolimnological organic matter archives.
73. 题目: Soil aggregation is more important than mulching and nitrogen application in regulating soil organic carbon and total nitrogen in a semiarid calcareous soil
Evaluating soil aggregation and microbial activities within soil aggregates contributes to understanding carbon (C) and nitrogen (N) cycling. Here we examined soil aggregate distribution, C and N pools, and extracellular enzymatic activities (EEAs) in soil aggregates after 16-year mulching (CT, no mulch; RF, plastic-mulched ridges and straw-mulched furrows; SM, straw mulch) and N fertilization (0, 120, and 240 kg ha−1). RF and SM significantly increased macroaggregate formation and aggregate stability (MWD, mean weight diameter) but N rate did not. Mulching had similar effects on aggregate-associated SOC (soil organic C) and TN (total N), with the order SM > RF > CT in macroaggregates and macroaggregate-occluded microaggregates. N input significantly increased TN in most cases, whereas its effect on SOC was only significant in SM. Notably, the majority of SOC and TN was isolated in the macroaggregate-occluded silt and clay fractions. SOC, TN, microbial biomass C (MBC), and microbial biomass N (MBN) decreased as aggregate-size decreased, whereas C- and N-acquiring enzymes varied greatly across aggregate fractions. Mulching had greater effects than N-fertilization on soil C and N pools and EEAs, whilst SM performed more beneficial effects than RF on SOC, TN, MBC, MBN, and EEAs. MBC rather than SOC was associated with MWD in bulk soil, while significant relations between MWD and SOC were observed in macroaggregates and macroaggregate-occluded microaggregates. Partial least squares path modeling illustrated that soil aggregation was the most important factor affecting SOC and TN, followed by mulching and N addition. Regression analysis further revealed that α-glucosidase and leucine aminopeptidase were major variables mediating SOC and TN dynamics at the aggregate scale. This study highlights the importance of macroaggregate-occluded microaggregate fraction sensitively evaluating soil C and N dynamics, and straw mulch can effectively increase soil aggregation and stabilization of C and N in semiarid areas with infertile soils.
74. 题目: Nitrogen loss from the coastal shelf of the East China Sea: Implications of the organic matter
Organic matter is a critical factor which regulates nitrogen loss pathways of denitrification and anammox for microbes in marine ecosystems. However, only a little attention has been paid to contrasting studies on denitrification and anammox in sandy and muddy sediments, especially in the coastal continental shelf dominated by sandy sediments. This study determined the bulk properties and associated microbial nitrogen transformation processes of surface sediments in the East China Sea coastal shelf, with the aim of gaining insight into the interaction of nitrogen loss with organic matter at the molecular level. The results illustrate that nitrogen loss dominates in organic-rich muddy sediments, and its denitrification rate (14.39 nmol N g−1 h−1) and anammox rate (2.73 nmol N g−1 h−1) are greater than those of sandy sediments (denitrification rate = 5.55 nmol N g−1 h−1, anammox rate = 1.57 nmol N g−1 h−1). Furthermore, determination of the mean summed ladderanes shows higher anammox generated in the muddy sediments with a value of 167.78 ng g−1 dw. Quantitative analysis demonstrated that organic-rich muddy sediments enhanced the copy number of the denitrifying functional gene nosZ and anammox functional gene hzsB. We inferred that the greater rate of nitrogen loss in muddy sediments was due to the coupling relationship between anammox and denitrification. Overall, the community distribution and abundance of denitrifying bacteria and anammox bacteria changed intricately under the influence of organic matter. Moreover, this study further improves the understanding of nitrogen loss pathways and mechanistic factors from sediments.
75. 题目: Role of fertilization regime on soil carbon sequestration and crop yield in a maize-cowpea intercropping system on low fertility soils
Achieving food security through intensive agricultural practices on low fertility soils is challenging as crop productivity is increasingly curtailed by the loss of soil structural stability and rapid depletion of soil organic carbon (SOC). As such, the conversion from traditional mono-cropping to legume-cereal intercropping, especially with integrated fertilization, may increase crop yields with the least ecological footprint. We set up a 2-year field experiment in a split-plot design with cowpea-maize monoculture and intercropping under different organic–inorganic fertilization regimes, including no fertilization (control), organic input only (compost), chemical input only (NPK), and multi-nutrient enriched compost (NPKEC). We observed that intercropped maize had a significantly higher biomass yield compared to the corresponding monoculture when fertilized with NPKEC fertilizer. However, cowpea biomass yield differences between monoculture and intercropped plots were comparable under all fertilization regimes. In contrast, the grain yield advantage of both maize and cowpea was significantly enhanced under the intercropping system compared to monoculture, with NPKEC showing the most significant effect among all fertilization regimes. When comparing the relative contribution of the fertilization regime to SOC, the NPKEC fertilizer provided the highest SOC-sequestration (0.30 Mg C/ha yr−1). At the same time, the effect of the cropping system on C-sequestration showed that intercropping provided the highest C-sequestration (0.17 Mg C/ha yr−1) compared to monocultures of both crops. Although compost application significantly increased mineral associated (MAOC) and particulate associated organic carbon (PAOC) concentrations compared to unfertilized control plots, NPKEC fertilization with intercropping system was the most effective combination causing the greatest increase of both soil C pools over time. Based on redundancy analysis (RDA), the positive association of MAOC and PAOC with C-sequestration suggests the importance of both organic fractions as primary C reservoirs conducting SOC storage. Importantly, although compost alone in association with intercropping had a lower C-sequestration, it was associated to a better soil structure as confirmed by its positive relationship with macro-and micro-aggregation, water stable aggregates (WSA), and mean weight diameter (MDA). Overall, our results indicate the importance of restoring soil structure in degraded soils through appropriate land management solutions, such as stoichiometrically balanced fertilization practices (NPKEC) and crop diversification (intercropping), in order to achieve significant gains in SOC storage and, ultimately, improve crop productivity.
76. 题目: Calcium-enriched biochar modulates cadmium uptake depending on external cadmium dose
The impact of calcium-enriched biochar (BC, containing Ca, Al, Fe and P as dominant elements in the range of 6.9–1.3% with alkaline pH) obtained from sewage sludge (0.1 or 0.5% in the final soil) on cadmium-induced toxicity (final dose of 1.5 mg Cd/kg in control and 4.5 or 16.5 mg Cd/kg soil in low and high Cd treatment) was tested in medicinal plant Matricaria chamomilla. Low Cd dose had typically less negative impact than high Cd dose at the level of minerals and metabolites and the effect of BC doses often differed. Contrary to expectations, 0.5% BC with a high Cd dose increased Cd accumulation in plants about 2-fold. This was reflected in higher signals of reactive oxygen species, but especially the high dose of BC increased the amount of antioxidants (ascorbic acid and non-protein thiols), minerals and amino acids in shoots and/or roots and usually mitigated the negative effect of Cd. Surprisingly, the relationship between BC and soluble phenols was negative at high BC + high Cd dose, whereas the effect of Cd and BC on organic acids (mainly tartaric acid) differed in shoots and roots. Interestingly, BC alone applied to the control soil (1.5 mg total Cd/kg) reduced the amount of Cd in the plants by about 30%. PCA analyses confirmed that metabolic changes clearly distinguished the high Cd + high BC treatment from the corresponding Cd/BC treatments in both shoots and roots. Thus, it is clear that the effect of biochar depends not only on its dose but also on the amount of Cd in the soil, suggesting the use of Ca-rich biochar both for phytoremediation and safer food production.
77. 题目: Size distributions, mixing state, and morphology of refractory black carbon in an urban atmosphere of northeast Asia during summer
Black carbon (BC) exerts profound impacts on air quality, human health, and climate. Here, we investigated concentrations and size distributions of refractory BC (rBC) and mixing state and morphology of rBC-containing particles in urban Seoul for 2019 summer. Mass concentrations of rBC ranged from 0.02 μgm−3 to 2.89 μgm−3, and daily maximums of rBC mass, daily minimums of rBC mass median diameter (MMD) (110–130 nm), and shell-to-core ratio (Rshell/core) occurred with NO2 maximums during morning rush hour. As the first report of ground observations on rBC mixing state, these results indicate that vehicle emissions are a major local source of rBC in Seoul. MMDs of 127–146 nm and the greatest mass loadings of ≥1 μg m−3 were accompanied by high O3 and PM2.5, in contrast to the largest MMDs (135–165 nm) associated with transport from upstream regions.
The average Rshell/core was 1.25 for the mass-equivalent diameter (DrBC) of 140–220 nm. Rshell/core increased gradually through the day and was positively correlated with Ox concentration, indicating photochemical aging of rBC particles. Co-emissions of rBC and volatile organic compounds from vehicles facilitated internal mixing during the daytime. However, Rshell/core tended to be low at temperature >~30 °C and 58 % of rBC with Rshell/core exceeding 1.25 were found at nighttime under relative humidity >75 %. These results demonstrate that the mixing state of freshly-emitted rBC particles was altered through coating by photochemically oxidized vapors during the day and hygroscopic growth at night. Additionally, the delay-time approach revealed rBC morphological characteristics, the most common being the bare type (74 %), and the attached type (6 %) was relatively large in numbers during morning rush hour. Therefore, it is suggested that during summer, rBC particles from traffic emissions should be considered in parallel to winter pollution mitigation strategies in urban atmosphere of northeast Asia.
78. 题目: In situ formed CaSO4 on waste dander biochar to inhibit the mineralization of soil organic carbon
In order to reduce CO2 emissions, as well as realize the resource utilization of waste dander (WD) and the goal of international “peak carbon dioxide emissions” and “carbon neutrality”, Biochar was prepared with WD via pyrolysis technology, achieving CaSO4 in situ generated on its surface, which could be used to inhibit soil organic carbon (SOC) from mineralizing and enhance soil carbon sequestration ability. The characterization results showed that the unstable carbon (C) structures as well as more conjugated structures were generated on Ca-BC, obtaining an increased C sequestration of Ca-BC to 21.70 %. With the application of Ca-BC, the mineralization rate of SOC was reduced to 0.451 mg CO2/(g·d), and the soil moisture content, pH and TOC content were increased to 45.48 %, 7.96 and 47.19 %. In addition, the bioinformatics analysis and redundancy analysis revealed that the application of Ca-BC promoted bacteria to convert into the stable C-dominant phyla (Firmicutes).
79. 题目: In situ formation of Ca(OH)2 coating shell to extend the longevity of zero-valent iron biochar composite derived from Fe-rich sludge for aqueous phosphorus removal
Despite being an effective and attractive functional strategy for aqueous phosphorus (P) removal, the use of zero valent iron (ZVI) biochar composites has been severely impeded by rapid self-erosion. We describe a new approach for extending the lifespan of Fe-rich sludge-derived ZVI biochar composites via CaCl2 modification. Preliminary results showed that composites obtained at 900 °C without modification (MBC900) and at 900 °C with 100 g Cl/kg addition (MBC900100) had the highest P removal efficiency. In subsequent batch experiments, MBC900100 exhibited more stable P adsorption capacities than MBC900 over a wide pH range (4–10) and at various dosages, which was enhanced by the presence of HCO3−. The theoretical maximum P adsorption capacities of MBC900 and MBC900100 were 227.14 and 224.15 mg g−1, respectively. Kinetic analysis indicated that chemisorption dominated the removal process. Continuous experimental data using the Yoon–Nelson model indicated that MBC900100 had a considerably longer half-penetration time. The primary mechanism of P removal by MBC900 was Fe/C micro-electrolysis. As the embedded CaO formed a dissolvable Ca(OH)2 shell in situ on the surface of MBC900100, the phosphate formed a precipitate with free Ca2+ before being removed via micro-electrolysis. Overall, CaCl2 modification successfully enhanced the longevity of the ZVI biochar composites.
80. 题目: Atmospheric deposition as a direct source of particulate organic carbon in region coastal surface seawater: Evidence from stable carbon and nitrogen isotope analysis
To assess the source characteristics of coastal aerosols and evaluate the contribution of atmospheric deposition to particulate organic matter in surface seawater, total suspended particulates (TSP) were collected at a shore-based site on the south coast of North Yellow Sea from December 2019 through November 2020. The samples were analyzed for total organic carbon (TOC) and nitrogen (TN) as well as stable carbon and nitrogen isotope (δ13C and δ15N). The results showed that the annual mean concentrations of TOC and TN were 5.36 ± 4.74 and 5.12 ± 6.52 μg m−3, respectively. δ13C fluctuated between −25.1 ‰ and −19.2 ‰ with an annual mean of −24.0 ± 1.0 ‰ and a significant seasonal variation (P < 0.05) characterizing by the enrichment in winter (−23.4 ± 0.6 ‰) compared to other seasons, which was probably related to the massive coal combustion. Besides, δ15N ranged from 7.9 ‰ to 21.1 ‰ with an annual mean of 12.5 ± 2.9 ‰ and a less pronounced seasonal pattern (P = 0.23). The Bayesian isotope-mixing model showed that, annually, the most important source of TSP was biogenic and biomass source (55.5 ± 10.8 %), followed by fossil fuel combustion (31.9 ± 9.0 %), while the marine contribution was less (12.6 ± 2.3 %). For TOC and TN, the dominated sources were fossil fuel combustion (47.7 ± 3.4 %) and biogenic and biomass source (57.3 ± 11.7 %), respectively. Furthermore, the model results indicated that the contribution of atmospheric deposition to suspended particulate matter in surface seawater was 18.0 ± 11.0 %, 17.1 ± 6.7 % and 10.2 ± 2.0 % in autumn, spring and summer, respectively. For particulate organic carbon in surface seawater, the contribution of atmospheric deposition was 35.2 ± 3.5 % in spring, highlighting the huge impact of atmospheric deposition on particulate carbon cycling in coastal waters.