161. 题目: Chemical modification of biochars as a method to improve its surface properties and efficiency in removing xenobiotics from aqueous media
Biochar (BC) is a carbonaceous material produced by pyrolysis of biomass, applied in various areas such as water purification, fuel production, soil amendment, etc. Many types of BC are characterized by insufficient textural parameters or poor surface chemistry, and hence by low adsorption capacity. This makes innovative chemical methods increasing BC ability to remove xenobiotics from aquatic environments highly needed. Many of them have already been described in the literature. This review presents them in detail and evaluates their effectiveness in improving textural parameters, surface chemistry, and adsorption capacity of BC.
162. 题目: A high-resolution refractory black carbon (rBC) record since 1932 deduced from the Chongce ice core, Tibetan plateau
Refractory Black carbon (rBC) emitted from the combustion of biomass and fossil fuels plays an important role in the climate system. In this study, we established a record of the rBC concentration spanning 1932–2013 from an ice core retrieved from the Chongce ice cap of the West Kunlun Mountains in the western Tibetan Plateau. The record showed an increasing trend since the 1980s. The mean concentration of rBC was 2.66 ng g−1 before 1980 and 5.33 ng g−1 since 1980. The significant increase since the 1980s was very different from similar records from European ice cores. An analysis of atmospheric circulation and backward trajectories suggested that former USSR, the Middle East, and South Asia were the most likely source regions for the rBC deposited at the Chongce ice cap. This conclusion was also supported by the historical emission data in these regions. Phase analysis indicated that high rBC concentrations were closely associated with drought-induced biomass burning in the rBC source regions at the decadal timescale. These findings suggested that anthropogenic emissions controlled the long-term rBC trend, while the peak phases were caused from an increase of biomass burning.
163. 题目: Interfacial chemistry of mercury on thiol-modified biochar and its implication for adsorbent engineering
Mercury pollution in surface/groundwater has been a serious environmental problem that threatens human health. In recent years, thiol-modified biochars have exhibited excellent but unstable removal of mercury, which is likely to be affected by structure and interfacial chemistry, but the mechanism remains unclear. In this study, 3-mercaptopropyltrimethoxysilane (3-MPTS) was used as thiolation reagent, the interfacial chemical processes of mercury (Hg2+ and CH3Hg+) on thiol-modified biochar (porous and multilayer structures) were revealed, and the key molecular mechanisms were clarified. Specifically, the structure of biochar affected the binding mode of 3-MPTS (mainly through hydroxyl and π bonds), the morphology of the polymer (flocculent or spherical), and the surface Hg atomic density (e.g., ρatom was 1068.5 vs. 3.0 #Hg/nm2 for CH3Hg+). Thiol-modified biochars exhibited more surface S, Si, O, N elements, more negative surface charges, and more surface defects, resulting in faster initial reaction rate (larger h2 and K2) and larger adsorption capacity (qm increased by 11-14 and 17-19 times, respectively) for Hg2+ and CH3Hg+ removal. The thiol groups played a major role, not only complexing with uncharged mercury species (Hg(OH)2 and CH3HgOH) but also promoting the monolayer adsorption of CH3Hg+. Although some thiol groups were oxidized or precipitated, the products (e.g., HgSO3 and HgS) were trapped by hydroxyl groups and π bonds. This study confirmed the potential of thiol-modified biochar in sorbent engineering with promising applications in mercury-contaminated surface and groundwater remediation.
164. 题目: Roles of extracellular polymeric substances on Microcystis aeruginosa exposed to different sizes of polystyrene microplastics
Extracellular polymeric substances (EPS) are important shields for microalgae when confronting with external stresses. However, the underlying roles of EPS in the interactions between microplastics (MPs) and microalgae remain poorly understood. In this study, three sizes of polystyrene (PS) MPs (20 nm, 100 nm, and 1 μm) were chosen for evaluating the compositions of EPS, secreted by Microcystis aeruginosa during exposure. The results indicated that the EPS compositions were different when M. aeruginosa was exposed to PS MPs of different sizes. The presence of EPS is helpful for alleviating the adverse effects of PS MPs on M. aeruginosa cell growth, photosynthesis, and oxidative stress. With the exception of the shading effect, insufficient EPS cause direct adsorption of unstable 1 μm PS MPs to the algal surface, which could destroy the cell wall. In contrast, aromatic proteins and fulvic acids are representative EPS components stimulated by 100 nm PS MPs, contributing to the self-aggregation and encapsulation of algal cells and availability of nutrients for algal growth, respectively. High amounts of polysaccharides were secreted by M. aeruginosa along with humic acids during exposure to 20 nm PS MPs, both of which are crucial in the homo-aggregation of 20 nm PS MPs toward minimize its adverse effects on M. aeruginosa. Together, these findings revealed the differences in EPS under the stimulation of PS MPs of different sizes and clarified the roles of different EPS components in resisting the adverse effects of PS MPs on M. aeruginosa.
165. 题目: Evaluation of the use of biochar to stabilize polycyclic aromatic hydrocarbons and phthalates in sediment
Three types of biochar (BC) (mulberry biochar (MB), wheat straw biochar, and pine tree sawdust biochar) were prepared and used to stabilize hydrophobic organic compounds (HOCs) in contaminated sediment. The kinetics of HOC adsorption to the BCs had two distinct stages. The second stage adsorption process was longer for MB than the other BCs, presumably because MB contained large pores, mesopores, and micropores. The adsorption isotherms for the three BCs were described well by the Freundlich model. The adsorption capacities of MB, WS and PT for HOCs ranged between 106.7 and 1202 μg/g, 135.1 and 1002 μg/g, and 255.6 and 909 μg/g, respectively. The apparent HOC adsorption coefficients (KBC–W) for the three BCs were determined from the isotherm data and were similar. The HOC log KOW values correlated well with the log KBC-W values. In sediment slurry experiments, HOCs were much more effectively stabilized by MB than wheat straw and pine tree sawdust biochar. This was probably because of the MB pore characteristics that favored adsorption of HOCs of various molecular sizes. The Fourier-transform infrared and Raman spectra indicated that the main binding mechanisms were hydrogen boding, hydrophobic interactions, and π–π interactions. MB was found to be a possible agent for stabilizing HOCs in contaminated sediment. HOCs in sediment slurry continued to become adsorbed to MB for a long time, indicating that relatively long reaction times should be allowed for in situ remediation using MB.
166. 题目: The synthetic composite materials using PHBV, nZVI and biochar enhanced denitrification performance in water treatment
Solid carbon source (SCS)-based denitrification is a promising technique for nitrogen removal from sewage. However, a sustainable and effective supply of carbon sources, crucial to denitrification performance, has always been challenging. This study developed four synthetic SCSs: biochar (BC), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), PHBV loaded on biochar (BCP), and PHBV loaded on biochar-supported nanoscale zero-valent iron (BCPF), to examine their denitrification efficiency enhancement. Insufficient carbon sources caused low nitrate removal (<45%) in the BC reactor during the entire experiment. At the biofilm formation stage (influent nitrate: 40 mg L-1), the relatively higher nitrate removal in biochar-based SCS reactors than in the P reactor in the first 4 h indicated that the biochar's rapid release of carbon sources played a priming role in denitrification. Then, the subsequent sharp decrease in nitrate removal revealed the biochar's unsustainable release of carbon sources for the denitrifiers. Similar to the P reactor, the nitrate removal in BCP and BCPF reactors gradually increased after 12 h until the 48 h mark, where the high nitrate removal efficiency was stabilized (P: 79.93%-93.74%, BCP: 86.90%-100%, and BCPF: 91.68%-100%), except in the BC reactor. Evidently, the decomposed products from PHBV provided sustainable carbon sources for the denitrifiers. Compared with the P reactor in the continuous running stage, BCP and (especially) BCPF reactors exhibited excellent resistance to load impact. Here, PHBV supplied sustainable carbon sources and electron donors for denitrification, while nZVI served as extra electron donors. The biochar dominantly provided habitats for denitrifiers and functioned as an electron mediator.
167. 题目: High concentration of black carbon in northern Pakistan: Characteristics, source apportionment and emission source regions
Atmospheric Black Carbon (BC) is one of the absorbing components of solar radiation which potentially affects human health and regional climate. In the current study, BC mass concentrations were regularly observed for pre-monsoon and monsoon seasons using the seven-channel aethalometer (AE-33) over Peshawar, Pakistan. The scarcity of BC measurement in this region is critical for air quality assessment, hence providing much importance to this article for control policy recommendations. The monthly mean BC showed a maximum value of 12.1 ± 5.4 μg/m3 during March and a minimum value of 6.4 ± 3.1 μg/m3 during July. The bimodal diurnal BC concentration was observed in between 05:00–08:00 and 20:00–24:00 LST having a maximum night/day ratio of 3.4 during April. Furthermore, the weekdays BC concentration was higher than weekend days having the highest weekdays concentration during March (12.9 ± 5.6 μg/m3) and the lowest concentration during July (6.9 ±0 .9 μg/m3). Moreover, BC contributed maximum of 22% to PM2.5 during April and minimum of 7% during June. The source apportionment of BC revealed that maximum value of BC emitted from fossil fuel (BCFF) and biomass burning (BCBB) were 9.90 ± 0.50 μg/m3 and 2.61 ± 0.49 μg/m3 during March showed a clear dominancy of BCFF over BCBB emission. Further the highest percentage contribution of BCFF and BCBB were found to be 80.45% and 22.27% to total BC during May and April, respectively. Finally, the cluster trajectory analysis showed that majority of the air pollutants were due to local emission rather than long range transport.
168. 题目: Application of carbon nitride nanosheets for adsorption of various humic substances from aqueous solutions
Humic substances (HSs) cause serious problems such as membrane fouling and disinfection by-products. Particularly, HSs as the main UV-quenching substances in landfill leachate pose great challenges. In this study, we evaluated the application of carbon nitride nanosheets (CN-Ns) for adsorption of various HSs, as well as leachate nanofiltration concentrates (LNCs). The characterization revealed that as increasing thermal oxidation temperature, the properties of CN-Ns were affected, such as morphology, porosity, and crystallinity. The surface area of CN-N at 575 ℃ (CN-N-575) was 145.3 m2·g-1, resulting in an enhanced adsorption performance. The adsorption capacity of CN-N-575 for lignite humic acid (LHA) and soil fulvic acid (SFA) was considerably greater than that of bulk CN; the maximum adsorption amounts of LHA and SFA were 143.11 and 63.27 mg C∙g-1, respectively. Upon adsorption, the removal rate of LHA and Elliott soil humic acid was about 90%. Among HSs and LNCs, the humic-like components showed superior affinity; in some cases, the removal rate reached 100%. The adsorption preference of aromatic compounds in HSs and LNCs was ascribed to π-electron interactions. The adsorption of LHA was more pH-dependent than that of SFA, attributed to the interactions (electrostatic, hydrogen bonding, and complexation) along with a specific conformation effect. The findings proved the great potential of CN-Ns in HSs adsorption, especially in the treatment of landfill leachate.
169. 题目: Response mechanism of sediment organic matter of plateau lakes in cold and arid regions to climate change: a case study of Hulun Lake, China
Lake organic matter is one of the important forms of terrestrial carbon, and its sedimentary evolution is affected by many factors such as climate and sources. However, few studies have been conducted on the feedback mechanism of the sedimentary evolution of organic matter to climate change in cold and arid lakes. Historical variations and compositions of sources of the sediment organic matter (SOM) of Hulun Lake, a typical lake in the cold and arid region of China, were studied by multiple methods. The interactions and fee7dback mechanisms between the sedimentary evolution of SOM and climate change, and compositions of SOM source change, were also discussed. Overall, the characteristic indexes of the SOM, including total organic carbon (TOC), carbon stable isotope (δ13C), carbon to nitrogen ratio (C/N), and fluorescence intensity (FI) of the protein-like component in water extractable organic matter (WEOM), showed obvious and uniform characteristics of periodical changes. The indexes were relatively stable before 1920, and fluctuated from 1920 to 1979. Since the 1980s, values of TOC, δ13C, and FI of the protein-like component in WEOM has increased, while C/N decreased. The absolute dominant contribution of terrestrial source to the SOM had changed, and the relative average contribution rate of autochthonous source increased from 17.6% before 1920 to 36.9% after 2000. The increase of temperature, strong evaporation concentration effect, and change of compositions of SOM sources are the important driving factors of the sedimentary evolution of organic matter in Hulun Lake.
170. 题目: Improving biochar properties by co-pyrolysis of pig manure with bio-invasive weed for use as the soil amendment
Over recent years, pyrolysis has grown into a mature technology with added value for producing soil improvers. Further innovations of this technology lie in developing tailor-made products from specific feedstocks (or mixtures thereof) in combination with adjusted mixing ratio-temperature regimes. In this context, co-pyrolysis of pig manure (PM) and the invasive plant Japanese knotweed (JK) at different mixture ratios (w/w) of 3:1 (P3J1), 1:1 (P1J1), and 1:3 (P1J3) and varying temperatures (400–700 °C) was studied to address the low carbon properties and heavy metals (HMs) risks of manure-derive biochars and beneficially ameliorate the bio-invasion situation by creating value from the plant biomass. Co-pyrolysis of PM with JK increased by nearly 1.5 folds the fixed carbon contents in the combined feedstock biochars obtained at 600 °C compared with PM-derived biochar alone, and all combined feedstock biochars met the requirements for soil improvement and carbon sequestration. The total HMs in PM biochars were significantly reduced by adding JK. The combined feedstock biochar P1J1 generated at 600 °C was the most effective in transforming Cu and Zn into more stable forms, accordingly reducing the associated environmental risk of heavy metal leaching from the biochar. In addition, the accumulation of macronutrients can be an added benefit of the co-pyrolysis process, and P1J1-600 was also the biochar that retained the most nutrients (P, Ca, Mg, and K).
171. 题目: Molecular-Multiproxy Assessment of Land-Derived Organic Matter Degradation over Extensive Scales of the East Siberian Arctic Shelf Seas
172. 题目: Applying synchronous fluorescence spectra with Gaussian band fitting and two-dimensional correlation to characterize structural composition of DOM from soils in an aquatic-terrestrial ecotone
Dissolved organic matter (DOM), the primary participant of carbon and nitrogen cycle, has a great impact on the behavior and fate of organic pollutants and heavy metals in eutrophic lakes. The dynamic spectral properties of DOM fractions were revealed in an aquatic-terrestrial ecotone under the different types of land use. Composite soil samples of different depths (0–20, 20–40 and 40–60 cm) were collected from four different land uses along a disturbed-impact gradient in Taihu Lake, China, i.e., grassland (GRL), forest land (FOL), paddy field (PAF), and vegetable field (VEF). DOM mainly consisted of tyrosine-like material (TYLF), tryptophan-like material (TRLF), microbial humic-like material (MHLF), fulvic-like material (FLF) and humic-like material (HLF) within all soil profiles, where TRLF was the dominant component (61.30 %) using synchronous fluorescence spectroscopy (SFS) combined with principal component analysis and Gaussian band fitting. Based on two-dimensional correlation spectroscopy with SFS and Fourier transform infrared, the variation order of DOM fractions was FLF → MHLF → HLF → TRLF → TYLF within the GRL soil profile, and MHLF exhibited an oppositive change with aliphatic OH and amide I in protein. The order of DOM fractions was MHLF → FLF → HLF → TYLF → TRLF within the FOL soil profile, and the change trend of MHLF remained oppositive with aliphatic OH and CO in ester. The order of DOM within the PAF soil profile fractions was TRLF → MHLF → HLF → TYLF → FLF, and changing trends of TYLF were oppositive to aliphatic OH, CH bending vibration, CH bending vibration and CO in ester. The order of DOM fractions was HLF → TYLF → TRLF → FLF → MHLF within the VEF soil profile, where the changing trend TYLF remained oppositive to aliphatic OH, CH deformations in lignin and aliphatic group and amide I in protein. This study may provide important support for alleviating lake water eutrophication or pollution.
173. 题目: Geographical constraints on chemodiversity of sediment dissolved organic matter in China's coastal wetlands
Dissolved organic matter (DOM) plays an important role in wetland carbon cycle; however, the geographical pattern of DOM chemodiversity and controlling factors are not very clear for coastal wetland sediments, especially at large spatial scale. To this end, twenty China's coastal wetlands were surveyed on a national scale for their sediment DOM and related environmental parameters, and the DOM molecular compositions were resolved by Fourier transform ion cyclotron resonance mass spectrometry and relevant bioinformatics. The chemodiversity of a total of 14, 343 DOM molecular formulas showed a clear geographical pattern: a decrease with an increase in latitude. The moisture and organic matter contents of sediments were key factors controlling DOM chemodiversity and decreased with the increasing latitude. In addition, the sediment with higher DOM molecular chemodiversity contained more unsaturated compounds, and lignin-like and tannins increased with the decreasing latitude. This study highlights the molecular characteristics of sediment DOM in China's coastal wetlands and helps to deepen the geographical knowledge of coastal wetland DOM.
174. 题目: Attribution of photocatalysis of fluorescent natural organic matter fractions to the alleviation of ceramic membrane ultrafiltration fouling
In this study, a novel composite functioned as adsorption-photocatalysis based on bismuth oxide (Bi2O3), reduced graphene oxide and titanium dioxide (TiO2) (labelled as BRGT) was applied in combination with ceramic membrane ultrafiltration to removal natural organic matter (NOM) and to mitigate membrane fouling. The mechanisms of NOM removal and of membrane fouling were investigated. The dual action of adsorption and photocatalysis by the BRGT effectively degraded NOM, giving a removal efficiency of 22.2% for dissolved organic carbon and 73.0% for UV absorbance at 254 nm. ·O2− radicals were mainly involved in the degradation of humic and protein/polyphenol-containing fluorescent components of NOM. BGRT had a high adsorption affinity for protein-like components, whose removal depended more on h+. The fouling behavior of the ceramic membrane was the result of pore blocking combined with cake filtration formation. BRGT mainly adsorbed hydrophobic components, which exacerbated the reversible fouling resistance and transformed the fouling mechanism from standard blocking into complete blocking. With increase of photocatalytic time, the hydrophobic fraction was converted into hydrophilic and transphilic fractions, and large and medium molecular weight organics were degraded into small molecules. In this case, the cake filtration formation occurred much earlier, with reversible membrane resistance reduced by 95.5% and irreversible membrane resistance reduced by 90.4% at 60 min. From the results we concluded that NOM can be effectively treated with adsorption-photocatalysis by BRGT, especially its fluorescent fractions, which has great potential in alleviating ceramic ultrafiltration membrane fouling.
175. 题目: Two different biochar-doped hydrogels affect the growth of arugula (Eruca vesicaria) under different irrigation period
Today, the decrease in water resources in the worldwide has become an undeniable reality. In addition to climate change, wild agricultural irrigation also increases the rapid consumption of this vital source. The main purpose of this study is to evaluate the effectiveness of olive tree-OTB and pine tree biochar-PTB used for enhancing the water retention capacity of hydrogel against water scarcity stress on the arugula plant.
The PVA/SA were used for hydrogel synthesis and 0.1%, 0.25%, 0.5%, and 1% OTB and PTB were used as additives in hydrogel. Characterization of hydrogels were carried out with SEM and FTIR analyzes. The swelling properties of hydrogels were determined gravimetrically. A 1% and 1.5% hydrogel/turf ratio was added to the pots to determine the effectiveness of hydrogels on growth parameters of arugula under the water scarcity.
Results and Conclusion
The results showed that biochar-doped hydrogels had higher swelling capacity than pure hydrogels. When the hydrogels achieved the equilibrium swelling capacity, the best efficiency was obtained from 1% PTB-doped hydrogel as 141.05% and 0.1% OTB-doped hydrogel as 103.60%. However, OTB-doped hydrogels faster swelled than PTB-doped hydrogels. The effects of hydrogels on growth parameters of arugula under different water scarcity were also determined. The results showed that 0.25% OTB- and 1% PTB-doped hydrogels had positive effects on plant under water scarcity. Besides that, the 1% hydrogel/turf ratio was enough for PTB-doped hydrogels for healthy plant. In summary, it was determined that it was appropriate to use pine tree biochar by doping in the hydrogels that will be applied in the fight against drought.
176. 题目: Organic carbon contents of mineral grassland soils in Switzerland over the last 30 years
Long-term monitoring data on the evolution of soil organic carbon (SOC) content and soil stocks are crucial considering climate change and carbon sequestration. Due to the slow processes involved, it takes longer time spans until changes in SOC stocks become detectable. Thus, long-term monitoring is essential.
Beside measurements, models are often used to report changes in SOC stocks for greenhouse gas (GHG) inventories. Consistent field data over extended periods are essential for validating such models whereby data from long-term monitoring is of great value. We present SOC measurements from the topsoil (uppermost 0.2 m) of 24 grassland sites of the Swiss Soil Monitoring Network (NABO) for six sampling campaigns from 1985 to 2014 and compare their evolution with predictions by the RothC model, which, for example, is used for the Swiss GHG Inventory. While there was no general temporal trend of the measured data over all sites, from a single site perspective, SOC stocks decreased/increased on 8% and 25% of the sites respectively. When comparing the measured data with the predictions from modelled values from RothC, a good fit was achieved in two thirds of the cases. However, at 5 out of the 24 sites (21%), the modelled SOC changes over time were lower than the measured ones. For 3 out of the 24 sites (12%) the model predicted higher SOC stock increases than were measured. Overall the modelled data fit well together with the measured ones. Most of the sites revealed stable values over time or increasing trends between 1985 and 2014, which might indicate that the SOC stocks potentially are in equilibrium and that the farming management used in Switzerland is suited to maintain these stocks in topsoils. There might not be a big potential for C sequestration, however, it is also very important to maintain SOC stocks over time. For future climate change scenarios accurate long-term SOC data and modelling are important for gathering the required information.
177. 题目: Residue incorporation and organic fertilisation improve carbon and nitrogen turnover and stabilisation in maize monocropping
Residue incorporation and organic fertilisation are recommended to increase soil organic matter (SOM) content, thus promoting the provision of multiple ecosystem services. However, the positive effect of crop residue on SOM is often considered rather low, thus requiring a deeper knowledge of their management. In addition, organic fertilisation is thought to be less efficient than mineral. In this context, it is important to understand the response of SOM pools to long-term crop residue incorporation and organic fertilisation and their effect on nutrient cycling and on feed production, in order to judge the sustainability of these practices. We carried out an in-depth multidisciplinary survey to investigate the effect of 28 years of residue incorporation combined with three different nitrogen (N) fertilisation strategies (manure, slurry and mineral) on density fractionated SOM pools differing for their turnover time, and on soil enzymatic activity in a monocropping maize system in NW Italy. Results showed that in the long-term crop production was not altered by organic fertilisation. Organic fertilisation in combination with residue incorporation led to the highest total organic C and total N content down to 90 cm, which was reflected in each SOM pool. In addition, regular applications of crop residue and manures markedly increased C- and N-degrading enzymes, thus enhancing the turnover rates of C and N. We conclude that combining crop residue with organic fertilisation enhanced the provision of regulating services and soil activity, and is a valid approach for maintaining sustainable production in agroecosystems.
178. 题目: Soil organic carbon sourcing variance in the rhizosphere vs. non-rhizosphere of two mycorrhizal tree species
Soil organic carbon (SOC) plays a central role in ecosystem carbon sequestration and climate change mitigation, and its stability and dynamics are related to sourcing from microbial vs. plant residues. However, SOC sourcing and its regulating mechanisms remain poorly understood in soil's most bioactive compartment, the rhizosphere, which may differ from non-rhizosphere and under different mycorrhizal tree species. To fill the knowledge gap, here we collect the rhizosphere and non-rhizosphere soils under an arbuscular mycorrhizal (AM; Castanopsis eyrie) vs. an ectomycorrhizal (ECM) tree species (Pinus massoniana) of varied tree diameters (i.e., ages) in the Gutianshan subtropical forest of China. Plant and microbial residual components are quantified by lignin phenols and amino sugars, respectively. Coupled with the measurements of soil, microbial community and plant litter properties, we assess potential mechanisms (i.e., saprotrophic bacteria competition, microbial necromass recycling/reuse, and substrate quality control) influencing the distribution of plant and microbial residues in the rhizosphere vs. non-rhizosphere. We show that lignin phenols are more concentrated in rhizosphere than non-rhizosphere SOC, especially under the ECM trees showing inhibited saprotrophic decomposition induced by competition between ECM fungi and (saprophytic) bacteria. Amino sugars are also more concentrated in the rhizosphere of ECM trees due to ECM fungal contribution, but not under AM trees exhibiting reduced fungal necromass stability partially reflected by low biomass-normalized necromass accumulation coefficients in the rhizosphere. As a result, ratios of amino sugars to lignin phenols are relatively lower in the rhizosphere than non-rhizosphere under AM tree, challenging the presumed microbial dominance in rhizosphere carbon accumulation. These results highlight differences in and controls on rhizosphere SOC sourcing related to different mycorrhizal tree species, providing new information on the mechanisms regulating soil carbon dynamics in root-soil systems.
179. 题目: Estimates of spatially and temporally resolved constrained organic matter and sulfur dioxide emissions over the Indian region through the strategic source constraints modelling
A reliable present-day database of aerosol emissions discharged into the atmosphere is required in aerosol-climate models to accurately predict the atmospheric aerosol burden and provide necessary information for developing air quality and climate policies.Here we present the newly derived spatially and temporally resolved constrained sulfur dioxide () and organic matter (OM) emissions over the Indian region.The derivation was done by constraining the scattering to absorbing aerosols with the simulated fields of aerosol single scattering albedo (SSA) in the general circulation model of Laboratoire de Météorologie Dynamique (LMDZT-GCM). The annual emission rate of the constrained OM and emission over the Indian region were estimated as and , respectively.The annual constrained OM and emitted over the Indo-Gangetic plain (central India) comprised about 55% (37%) and 45% (44%) of their total emission strength over the Indian subcontinent, respectively.The constrained emission (1609–2474 Gg) exhibited a relatively lower monthly variability than the OM emission (197–1182 Gg), with the highest (lowest) OM and monthly emission being, respectively, during March (July) and February (July).The distinct spatial and temporal changes in and OM emissions, as depicted from the z-score mapping, were governed by the change in their emission strength mainly from the fossil fuel (viz.industrial sector) and biomass combustion (viz.forest and crop-waste), respectively.The annual emission rate of constrained BC emission from the industrial sector () and that of OM from the domestic sector() resembled well the recent bottom-up emission over India. The missing amount of source-sector-wide bottom-up emissions were identified by comparing the constrained with bottom-up emissions for reconciliation.
180. 题目: Organic amendments enhanced the humification degree in soil formation of bauxite residue
Revegetation of bauxite residue disposal areas is an effective disposal strategy for large-scale in-situ disposal and reduction of environmental risk. The application of organic amendments is an effective method of increasing the organic carbon content of residue. Humification of bauxite residue by different types of organic amendments in the synergistic effect of Ca-containing solid waste was investigated.
100-day incubation experiments using Fourier Transform Infrared Spectroscopy (FTIR), Excitation-Emission Matrix (EEM) fluorescence, Ultraviolet–Visible (UV–Vis) spectroscopy, Illumina high-throughput sequencing technology for the analysis of bauxite residue treated with different organic amendments. The organic amendments treatments applied included corn straw (BGS), nitrohumic acid (BGH), and poultry manure (BGM), and the pretreated residue (desulphurization gypsum mixed with bauxite residue) was the BG.
The composition and parameters of humic substances of bauxite residues with different treatments was ranked as BG < BGM < BGS < BGH. BGS treatment has the highest humification rate. For carbon cycle-related enzymes, enzyme activities of corn straw treatment were higher, indicating that straw addition was more intense on carbon turnover. Combined with microbial activity, the manure had sufficient nutrients, which was conducive to microbial growth and reproduction. Redundancy analysis (RDA) and two-factor correlation network showed that microorganisms influence humification characteristics by secreting carbon cycle-related enzymes.
The nitrohumic acid treatment had a higher humification degree but limited microbial activity, whilst corn straw treatment had a wide potential for humification and enzyme activity. Desulfurization gypsum and corn straw have novel application prospects on ecological rehabilitation at disposal areas.