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22821. 题目: Contribution of Water-Soluble Organic Matter from Multiple Marine Geographic Eco-Regions to Aerosols around Antarctica | |||||
22822. 题目: Kinetics and fractionation of carbon and oxygen isotopes during the solid-phase transformation of biogenic aragonite to calcite: The effect of organic matter The phase transformation of biogenic shells from aragonite to calcite can modify the primary carbon and oxygen isotopic values (δ13C and δ18O), and thus affect their significance as paleoenvironmental proxies. While the biasing of δ13C and δ18O by dissolution and reprecipitation phase transformation (DR) has been extensively studied, thermal solid-phase transformation (SPT) in archaeological shell middens is rarely considered. In this study, the effects of intra-crystalline organic matter on the kinetics and carbon and oxygen isotopic fractionation during thermal SPT are evaluated by comparing two sets of experiments on powdered aragonite snail shells heated in air and pure nitrogen atmospheres. The results show that during heating temperature below 400 °C, the intra-crystalline organic matter could inhibit the phase transformation due to the shielding effect of organic matter, while during heating temperature above 400 °C, the decomposition of the intra-crystalline organic matter increases the kinetic rate of the phase transformation. The activation energy for the phase transformation was determined to be +150.5 kJ·mol−1, lower than that of +247 kJ·mol−1 obtained for abiogenic polycrystalline aragonite and close to that of +158 to +163 kJ·mol−1 for abiogenic single crystal aragonite. This is attributed to the larger lattice parameter c in biogenic aragonite and the increasing porosity of calcium carbonate with the decomposition of organic matter. In a nitrogen atmosphere, the deviation of δ13C and δ18O between the heated sample (the mixture of aragonite and calcite) and the original shell aragonite (Δ13CM-A and Δ18OM-A) is negligible during heating temperature below 400 °C; however, Δ13CM-A (from −0.43‰ to 0.00‰) and Δ18OM-A (from −1.54‰ to −0.02‰) are significant during heating temperature above 400 °C. The temperature-dependence of Δ13CM-A in biogenic carbonates is much more significant than that in abiogenic carbonates, which clearly reflects the occurrence of isotopic exchange between the intra-crystalline organic matter and the carbonates. In air, the heating-induced calcium carbonate is depleted in δ13C by up to −0.48‰ and in δ18O by up to −3.46‰, compared with the original samples, which is mainly caused by isotopic exchange with the external carbon dioxide in air and the intra-crystalline organic matter, with the latter being the dominant source. Our results demonstrate that the decomposition of the intra-crystalline organic matter increases the kinetic rate and induces carbon and oxygen isotope fractionation during SPT from aragonite to calcite. This study provides direct evidence for evaluating the preservation of carbon and oxygen isotopes of biogenic calcium carbonate shells which have undergone the SPT process in archaeological shell middens. | |||||
22823. 题目: Deciphering the rhizosphere microbiome of a bamboo plant in response to different chromium contamination levels Bamboo has been considered a potential plant species for phytoremediation due to its high biomass and heavy metal (HM) resistance. However, little is known about the interactions between bamboo and soil microbial activities in HM-contaminated soils. Here, we investigated the characteristics of microbial communities in the rhizosphere soil of Lei bamboo (Phyllostachys praecox) along a chromium (Cr) gradient. We found that the soil Cr content was positively correlated with the total organic carbon (TOC) and HCl-extractable Cr but negatively correlated with the pH and bacterial and fungal Shannon indices. Proteobacteria and Ascomycota predominated in the bamboo rhizosphere under Cr pollution. A co-occurrence network showed that two of the most Cr-sensitive bacterial genera and keystone taxa were from the Acidobacteria, indicating that this phylum can be as an indicator for the studied Cr-polluted soils. Redundancy analysis revealed that both the soil bacterial and fungal community compositions were significantly correlated (p < 0.05) with Cr, pH, TOC, alkali-hydrolysable N (AN), and available phosphorus (AP). The increase in TOC as the Cr content increased can be ascribed to an adverse Cr effect on the soil microflora, probably because the microbial biomass was less effective in mineralizing soil C under Cr-polluted conditions. | |||||
22824. 题目: Metagenomics and stable isotope probing reveal the complementary contribution of fungal and bacterial communities in the recycling of dead biomass in forest soil Forest soils represent important terrestrial carbon (C) pools, where C is primarily fixed in plant biomass and then is incorporated in the biomass of fungi and bacteria. Although classical concepts assume that fungi are the main decomposers of the recalcitrant organic matter within plant and microbial biomass, whereas bacteria are considered to mostly utilize simpler compounds, recent studies have shown that fungi and bacteria overlap in substrate utilization. Here, we studied the microbial contribution to the recycling of dead biomass by analyzing the bacterial and fungal communities in soil microcosms supplemented with 13C-labeled biomass of plant, fungal, and bacterial origin using a combination of DNA-stable isotope probing and metagenomics. Both fungi and bacteria contributed actively to the degradation of complex components of plant and microbial biomass. Specific families of carbohydrate-active enzymes (CAZyme) were involved in the degradation of each biomass type. Moreover, the analysis of five bacterial metagenome-assembled genomes indicated the key role of some bacterial genera in the degradation of plant biomass (Cytophaga and Asticcacaulis) and microbial biomass (Herminiimonas). The enzymatic systems utilized by bacteria are highly complex and complementary but also highly diverse among taxa. The results confirm the importance of bacteria, in addition to fungi, as decomposers of complex organic matter in forest soils. | |||||
22825. 题目: Influence of high carbonization temperatures on microstructural and physicochemical characteristics of herbaceous biomass derived biochars This study investigated the influence of high carbonization temperatures on the microstructural, textural, and physicochemical characteristics of Kanlow Switchgrass and Public Miscanthus derived biochars. Biochars were produced at three carbonization temperatures of 500, 700 and 900 °C. pH values of the biochars increased from slightly alkaline to highly alkaline as carbonization temperature increased. Electrical conductivities of the biochars were between 1.21 and 4.07 mS/cm. The specific surface areas of the Kanlow Switchgrass derived biochars increased from 0.91 to 519.49 m2/g and 0.25 to 783.74 m2/g for Public Miscanthus derived biochars as carbonization temperature increased. Surface topographies of the biochars showed that all the biochars had visible pores of varying sizes and shapes. Raman spectra for all the biochars showed overlapping D and G bands. XPS analysis showed a reduction in the atomic percentage of oxygen functional groups as carbonization temperature increased. The improvement in the characteristics of the biochars showed that high carbonization temperatures can significantly enhance the satisfactory performance of herbaceous biomass-derived biochar as a solid fuel, adsorbent, and soil amendment. | |||||
22826. 题目: A field system for measuring plant and soil carbon fluxes using stable isotope methods There is a lack of field methods for measuring plant and soil processes controlling soil organic matter (SOM) turnover over diurnal, seasonal, and longer time‐scales with which to develop datasets for modelling. We describe an automated field system for measuring plant and soil carbon fluxes over such time‐scales using stable isotope methods, and we assess its performance. The system comprises 24 large (1‐m deep, 0.8‐m diameter) cylindrical lysimeters connected to gas‐flux chambers and instruments. The lysimeters contain intact, naturally‐structured C3 soil planted with a C4 grass. Fluxes of CO2 and their 13C isotope composition are measured 3‐times daily in each lysimeter, and the isotope composition is used to partition the fluxes between plant and soil sources. We investigate the following potential sources of error in the measurement system and show they do not significantly affect the measured CO2 fluxes or isotope signatures: gas leaks; the rate of gas flow through sampling loops; instrument precision and drift; the concentration‐dependence of isotope measurements; and the linearity of CO2 accumulation in the chambers and associated isotope fractionation resulting from different rates of 13CO2 and 12CO2 diffusion from the soil. For the loamy grassland soil and US prairie grass (Bouteloua dactyloides ) tested, the precision of CO2 flux measurements was ±0.04% and that of the flux partitioning ±0.40%. We give examples of diurnal and seasonal patterns of plant and soil C fluxes and soil temperature and moisture. We discuss the limitations of the isotope methodology for partitioning fluxes as applied in our system. We conclude the system is suitable for measuring net ecosystem respiration fluxes and their plant and soil components with sufficient precision to resolve diurnal and seasonal patterns. | |||||
22827. 题目: Composition and photo-reactivity of organic matter from permafrost soils and surface waters in interior Alaska | |||||
22828. 题目: Characterizing chemical composition and light absorption of nitroaromatic compounds in the winter of Beijing Nitroaromatic compounds (NACs) were believed as one of the major light absorption components in brown carbon (BrC) and important fractions of organic aerosols. To understand the chemical compositions and light absorption of NACs in the highly polluted atmospheres, a field campaign was conducted in the winter of urban Beijing. Ambient PM2.5 samples were collected and a total of 12 NACs were identified and quantified using ultrahigh performance liquid chromatography coupled to Orbitrap mass spectrometer. Light absorption of methanol-extracted BrC and individual NAC in PM2.5 were also measured using UV–Vis spectrophotometer. The average concentration of quantified NACs was 173 ± 137 ng/m3, ranging from 19 to 585 ng/m3, which was much higher than those in summer in Beijing or in winter in other areas. Nitrophenols and nitrocatechols are the dominant species among the identified NACs in the winter of Beijing. Four pollution episodes were observed during the observation. The NAC concentrations increased from 62 ng/m3 during clean days to 224 ng/m3 during pollution episodes, with both secondary formation and biomass burning emissions as important sources. Particulate BrC was estimated to contribute as high as 45% of the total light absorption of carbonaceous aerosols at 370 nm based on the online aethalometer measurement. The identified NACs contributed about 17% of the total absorption by methanol-extracted BrC at 370 nm, though the mass concentrations of quantified NACs only accounted for 0.6% of the organic matter. This indicates the high absorption capability of NACs, which needs to be taken into consideration when studying the aerosol light absorption in urban environments. Moreover, the maximum absorption values of NACs among the range of 300–400 nm made them important to atmospheric photochemistry reactions. The linkage between chemical compositions and light absorption of NACs deserves to be further investigated to understand the light absorption mechanisms and environmental impacts of organic aerosols. | |||||
22829. 题目: A comprehensive study on phase inversion behavior of a novel polysulfate membrane for high-performance ultrafiltration applications The microorganisms and natural organic matters (NOM) in the water significantly threaten the health of human being, thus, it is an emerging demand for removal of those pollutes via the cost-efficient ultrafiltration technique. Non-solvent induced phase separation (NIPS) is the most frequently employed method for preparing ultrafiltration membrane in industry, however, the intrinsic weaknesses of porous polymeric membranes, e.g. weak mechanical property, foulants adsorption, and low-resistance to acidic/basic conditions, greatly hamper their applications. Thus, novel polymer materials are required to tackle the issues. In this study, we used a novel polymer, polysulfate (PSE) and adopted it for preparing ultrafiltration membrane via NIPS approach. The phase inversion process of the PSE casting membrane was comprehensively studied by choosing different solvents and water as coagulation bath. The top surface (TS) pore size of the resultant membranes was tailored by changing the solvent or tuning the polymer concentration, reaching as small as 10 nm with a porosity of 82.6 ± 0.9%. The ultrafiltration performance of the optimized membrane outperforms most of the polymeric membranes, which shows both high flux of 135.8 ± 10.7LMH and rejection efficiency of 99.1 ± 0.83% for 100 ppm HA aqueous solution. Furthermore, the prepared membrane also owns antifouling and acid/alkaline-resistance characters, which endow the PSE membrane with great promise in the future industrially ultrafiltration applications. | |||||
22830. 题目: Using EEM fluorescence to characterize the membrane integrity of membrane bioreactor (MBR) In this study, a novel method for EEM fluorescence spectra examination of the membrane integrity in MBRs was investigated. Dissolved organic matter (DOM) was measured to determine the performance of membrane retention. The sensitivity of membrane integrity tests which reported as a log reduction value (LRV) was recalculated. The results show that, two protein-like species, one humic-like species and one fulvic-like species were found in MBRs using parallel factor analysis (PARAFAC). When the membrane pore size was 0.2 μm, the majority of macromolecular protein-like species could be effectively rejected. The fluorescence regional integration (FRI) results for the tryptophan species and the aromatic protein species showed a positive correlation with the different breakage rates of fibers, the correlation coefficients were 0.980 and 0.987, respectively. In comparison with particle counting detection, EEM fluorescence spectral analysis exhibits good practicability with regards to response time and feedback accuracy. With an LRV of 4.26, it can detect the water quality and membrane integrity without having to add other substances as tracers. In addition to expanding the membrane integrity technologies, this study also provides a method for real-time membrane filtration detection and water quality analysis in MBRs. | |||||
22831. 题目: The contribution of methane photoproduction to the oceanic methane paradox Although methanogenesis is considered a strictly anaerobic process, oxygen‐replete surface open‐ocean waters are usually supersaturated with methane (CH4), a phenomenon termed the oceanic methane paradox. Here we report that abiotic methane photoproduction from chromophoric dissolved organic matter (CDOM) significantly contributes to this paradox. Methane photoproduction was observed during solar‐simulated irradiations of various waters collected along the land‐ocean continuum. Methane photoproduction rates decreased seaward, whereas its relative production efficiency and the methane‐to‐carbon‐monoxide (CO) photoproduction ratio (ΔCH4/ΔCO) both followed a reversed trend. Remote‐sensing modeling incorporating a ΔCH4/ΔCO–CDOM absorption relationship yielded an annual methane photoproduction of 118 Gg for the global open ocean, accounting for 20‐60% of the open‐ocean methane efflux and being of comparable magnitude to the upper‐ocean methane microbial‐oxidation sink. The photodegradation of CDOM thus plays an important role in maintaining supersaturated methane concentrations in the oxygenated upper ocean and in sustaining oceanic methane emissions to the atmosphere. | |||||
22832. 题目: Vis-SWIR spectral prediction model for soil organic matter with different grouping strategies The effect of soil organic matter (SOM) on the spectral characteristics of soil differs among soil samples of different soil types with various mineral contents or mechanical compositions. SOM prediction models with visible and near-infrared and shortwave infrared (Vis-SWIR) spectral variables for grouping soil samples are more accurate than global modeling methods. However, the optimal grouping method must be explored. We measured the Vis-SWIR (400–2500 nm) spectral reflectance of 274 soil samples from the Songnen Plain and applied different grouping strategies, including traditional soil grouping, spectral clustering grouping and decision tree grouping considering both traditional grouping information and spectral information. The original reflectance, continuum removal, and first-derivative reflectance were analyzed with competitive adaptive reweighted sampling (CARS), and the results were used as inputs to establish a random forest model for SOM prediction. The following results were obtained: (1) the decision tree grouping method is the optimal grouping strategy for the SOM prediction model; (2) among different inputs, first-derivative reflectance is optimal; and (3) CARS is an effective way to reduce the number of inputs and improve the prediction accuracy of SOM. This study provides an effective soil grouping methodology for SOM estimation at the soil great group level. | |||||
22833. 题目: Soil organic matter dynamics and microbial metabolism along an altitudinal gradient in Highland tropical forests The highland forests of tropical regions are highly vulnerable to climate change because changes in soil organic quality due to the increased soil water deficit conditions through rising temperatures. Several authors have reported that labile molecules dominate soil organic matter at higher elevations, and it is therefore more vulnerable to the rising temperatures associated with climate change. The objective of the present study was to analyze the effect of interaction between the chemical composition of organic matter derived from the dominant plant species and the metabolism of microbial community along an elevational gradient in a highland forest in Central Mexico. The study compared three vegetation-soil systems that represent three different elevational levels: Alnus-system (3100 m.a.s.l.), Abies-system (3500 m.a.s.l.) and Pinus-system (3700 m.a.s.l.). The SOM produced in the lowest site is more recalcitrant (i.e., higher Alkyl:O-Alkyl ratio) as a result of the lower water availability than in the highest site. The results of Threshold Elemental RatioC:N (TERC:N) and TERC:P for the organic layer were lower than their C:N and C:P ratios in the organic layer, supporting that the microbial community of the organic layer in the site of lowest elevation must be limited by the carbon source, rather than by N and P. However, these results were not found in the mineral soil, suggesting that the drivers of organic matter decomposition differ between the organic layer and the mineral soil. As a conclusion, our results suggest that the chemical recalcitrance of organic matter (at the lowest site) and temperature (at the highest site) reduce the microbial metabolic activity in the forest floor. Integrated study of plant-derived organic material and the microbial metabolism of the forest floor is therefore required to achieve a full understanding of the vulnerability of tropical mountain ecosystems to climate change. | |||||
22834. 题目: Visible-light-excited humic acid for peroxymonosulfate activation to degrade bisphenol A In this study, a novel peroxymonosulfate (PMS) activation method by visible light (VL) excited humic acid (HA) was developed and applied to degradation of bisphenol A (BPA). Results showed that, in HA (2 mg/L)/PMS (1 mM)/VL system, the degradation rate of BPA could reach 95.4% within 30 min, which was much higher than that of HA/VL system (9.4%) and PMS/VL system (15.5%). Meanwhile, the concentration of HA was also decreased in this process and the original structure of HA was obviously destroyed. Reaction mechanism accounting for the effect of HA on BPA degradation in the PMS/HA/VL system was explicated by the quenching experiments, electron paramagnetic resonance (EPR) detection and HA fractionation experiments. Results showed that singlet oxygen (1O2), hydroxyl radical (OH) and sulfate radical (SO4−) were all involved in the system, and 1O2 was the primary reactive species responsible for BPA degradation. The aromatic constituents of HA made the dominant contribution to the generation of reactive species, in which the phenolic groups played the role of electron-donor, and the quinone moieties acted as the electron shuttles could accelerate the electron-transfer between HA and PMS, which thus activated PMS to form the reactive species for BPA degradation. As HA is ubiquitous in nature, this study may provide a new insight into the in situ water treatment with the assistance of PMS. | |||||
22835. 题目: Optimization of preparation conditions for biochar derived from water hyacinth by using response surface methodology (RSM) and its application in Pb2+ removal In this study, response surface method (RSM) was adopted to optimize the preparation conditions of water hyacinth biochar. The interaction on Pb2+ adsorption performance between the three basic preparation conditions of heating time (X1), heating temperature (X2) and heating rate (X3) were designed by Box-Behnken Design (BBD). The results showed that the mathematical model can fit the experimental data well. The significance of a single factor affecting followed by X2 > X3 > X1, and the interactive items as follows: X1X2 > X2X3 > X3X1. Through the analysis of variance and the numerical expectation function method, the optimal heating time is 2.65 h, heating temperature is 433 ℃, and heating rate is 19.96 ℃/min. The water hyacinth biochar was prepared under optimized conditions (OWHBC) to adsorb 50 mg/L Pb2+ solution. The actual experiment value of adsorption capacity (q) for Pb2+ was 24.94 mg/g, the predicted value of the model was 24.95 mg/g, and the error was only 0.02%. The maximum theoretical adsorption capacity (Qm) obtained with the Langmuir model were 195.24 mg/g for WHBC (prepared at center values of preparation conditions from single-factor experiments: 3 h, 400 ℃, and 20 ℃/min) and 251.39 mg/g for OWHBC, respectively. Through the determination of pH and specific surface area of biochar before and after optimization, it is proved that the RSM is feasible to optimize the preparation conditions of biochar. The results showed that RSM could optimize the preparation conditions of water hyacinth biochar and improve the adsorption ability of OWHBC to Pb2+. | |||||
22836. 题目: Soybean ( Glycine max (L.) Merrill) intercropping with reduced nitrogen input influences rhizosphere phosphorus dynamics and phosphorus acquisition of sugarcane ( Saccharum officinarum ) | |||||
22837. 题目: Safety evaluation and ibuprofen removal via an Alternanthera philoxeroides -based biochar | |||||
22838. 题目: Application of sodium percarbonate activated with Fe(II) for mitigating ultrafiltration membrane fouling by natural organic matter in drinking water treatment It remains challenging to efficiently mitigate membrane fouling caused by natural organic matter (NOM) for the widespread application of ultrafiltration process. In this study, sodium percarbonate activated with Fe(II) (Fe(II)/SPC) was proposed as a feedwater pretreatment strategy for membrane fouling control. Typical NOM fractions, i.e., humic acid (HA), bovine serum albumin (BSA) were employed as membrane foulants, as well as natural surface water. The results showed that Fe(II)/SPC pretreatment apparently alleviated membrane fouling by BSA and HA-BSA, and the performance outperformed Fe(II) pre-coagulation and SPC pre-oxidation alone. Considering HA fouling, more severe flux decline and increased reversible fouling resistance were obtained, while irreversible fouling was slightly mitigated. The filtration of HA-BSA was well fitted to intermediate blocking followed by cake filtration, and Fe(II)/SPC noticeably increased the filtration volume corresponding to the formation of cake filtration. With Fe(II)/SPC pretreatment, a sparser and more homogeneous foulant layer with lower resistances was observed on membrane surface, and Fourier transform infrared spectroscopy indicated that the peak intensities of major functional groups for organic pollutants were significantly decreased. In surface water treatment, Fe(II)/SPC could effectively improve membrane filtration behavior and pollutants removal, with a distinct decrease of both fluorescent fractions and different molecular weight organic compounds. It seemed that hydroxyl radical oxidation and coagulation with in-situ formed Fe(III) were the main mechanisms of contaminants removal and membrane fouling control. Overall, this combined process exhibited a great potential for actual application during drinking water treatment. | |||||
22839. 题目: The effect of chemical and organic N inputs on N2O emission from rain-fed crops in Eastern Mediterranean Nitrogen has a significant contribution to global warming and its reduction in agriculture is expected to reduce N2O emissions having however adverse effects on the productivity of agricultural ecosystems. Maintaining systems productivity with alternative N sources i.e manure and composts could be a strategy also to mitigate N2O emissions. In this paper, we present the effect of different N sources (organic and chemical) on field N2O emissions and how these emissions are associated with soil available N forms (NH4+ and NO3−) in three different rain-fed crops namely barley, pea and vetch grown in Cyprus for two growing seasons. The daily emissions ranged from −3.11 to 12.3 g N–N2O/ha/day, while cumulative emissions ranged from 119 g N–N2O/ha to 660 g N–N2O/ha depending on crop and nitrogen source type. The emissions showed a seasonal pattern and WFPS has been identified as a critical soil parameter controlling daily N2O emissions. The daily N2O fluxes in the current study derives mainly from nitrification irrespectively crop type or nitrogen source type. Specific emission factors for each crop cultivated under different N source type were calculated and ranged from 0.03% ± 0.02–0.34% ± 0.09. The application of manure and chemical fertilizers cause similar intensity of N2O emissions while compost exhibited the lower emission factors. These findings suggest that composts could be integrated in a nutrient management strategy of rain-fed crops with less N2O emissions. The high background emissions found suggest also that other factors than external inputs are associated with N2O emissions and further studies including the response of microbial community structure and their contribution and association with N2O emissions. | |||||
22840. 题目: Toxicological effects of chlorophenols to green algae observed at various pH and concentration of humic acid Humic acid (HA) is ubiquitous organic matter derived by microbial metabolisms. This polymeric substance has both hydrophilic and hydrophobic moieties, and it is known that they affect to bioavailability of environmental pollutants. Objective of this study is to investigate the toxicological effects of chlorophenols to green algae observed at various pH and concentration of HA. Toxicity was determined by algal growth inhibition rate and EC50 of green algae Chlorella vulgaris. As a result, toxicity of 2,4-dichlorophenol was mitigated with increase of the coexisting amount of HA and solution pH. In the case of coexisting 2.5 ppm HA, EC50 of 2,4-dichlorophenol was 12.2 ppm and approximately three times higher than the case of absence of HA at pH 7.5. Meanwhile, Toxicity of 2,4,6-trichlorophenol was enhanced with increase of the coexisting amount of HA. In the case of absence of HA, EC50 of 2,4,6-trichlorophenol was 13.1 ppm and approximately two times higher than the case of coexisting 2.5 ppm HA at pH 7.5. Results suggested that toxicity of chlorophenols is influenced by the electrostatic and hydrophobic interaction between HA and chlorophenols. The hypothesis of toxicity enhancement pathway was proposed in the case of equilibrium-state 2,4,6-trichlorophenol between anionic and nonionic states. | |||||
