321. 题目: Fractionation of levofloxacin and ofloxacin during their transport in NOM-goethite: Batch and column studies
Adsorption and transport of levofloxacin (LEV) and ofloxacin (OFL) enantiomers in a matrix containing goethite and natural organic matter (NOM) were investigated using batch and column experiments. In batch studies, competition and enantioselectivity were observed in the adsorption of LEV and OFL. Enantioselectivity upon adsorption was investigated by comparing changes in the enantiomer fraction (EF) (the ratio of LEV to the sum of LEV and OFL remaining in the solution) after and before adsorption. At pH < 7, there was hardly any selectivity in adsorption of OFL and LEV to goethite. At pH > 7, OFL showed a stronger adsorption than LEV to goethite, and this preference remained when NOM samples of Leonardite humic acid (LHA) and Elliott Soil fulvic acid (ESFA) were added. However, when Suwannee River NOM (SRNOM) was added, the preference was reversed, and LEV was adsorbed more strongly. In single systems, the presence of different types of NOM increased adsorption of LEV and OFL, especially LEV. In column studies, preloaded NOM decreased the transport of LEV and OFL through goethite-coated sand. The EF values in the effluent increased with retention time and reached the largest values (0.59–0.72) at around 1.5 pore volume (PV), and then decreased again, reaching a stable value at 5.0–30.0 PV. Both batch and column experiments showed that, fractionation of LEV and OFL occurred during adsorption and transport in the presence of NOM-goethite complexes, which would eventually affect their environmental fate.
322. 题目: NOM fractionation by HPSEC-DAD-OCD for predicting trihalomethane disinfection by-product formation potential in full-scale drinking water treatment plants
Chlorination is a common method for water disinfection; however, it leads to the formation of disinfection by-products (DBPs), which are undesirable toxic pollutants. To prevent their formation, it is crucial to understand the reactivity of natural organic matter (NOM), which is considered a dominant precursor of DBPs. We propose a novel size exclusion chromatography (SEC) approach to evaluate NOM reactivity and the formation potential of total trihalomethanes-formation potentials (tTHMs-FP) and four regulated species (i.e. CHCl3, CHBrCl2, CHBr2Cl, and CHBr3). This method combines enhanced SEC separation with two analytical columns working in tandem and quantification of apparent molecular weight (AMW) NOM fractions using C content (organic carbon detector, OCD), 254-nm spectroscopic (diode-array detector, DAD) measurements, and spectral slopes at low (S206-240) and high (S350-380) wavelengths. Links between THMs-FP and NOM fractions from high performance size exclusion chromatography HPSEC-DAD-OCD were investigated using statistical modelling with multiple linear regressions for samples taken alongside conventional full-scale as well as full- and pilot-scale electrodialysis reversal and bench-scale ion exchange resins. The proposed models revealed promising correlations between the AMW NOM fractions and the THMs-FP. Methodological changes increased fractionated signal correlations relative to bulk regressions, especially in the proposed HPSEC-DAD-OCD method. Furthermore, spectroscopic models based on fractionated signals are presented, providing a promising approach to predict THMs-FP simultaneously considering the effect of the dominant THMs precursors, NOM and Br−.
323. 题目: Particulate and mineral-associated organic carbon fractions reveal the roles of soil aggregates under different land-use types in a karst faulted basin of China
Soil aggregation has been recognized as the main mechanism of organic carbon (C; OC) stabilization, and OC dynamics within aggregates are closely linked to soil OC (SOC) sequestration. To unravel the roles of different-sized aggregates and the associated OC fractions in SOC accumulation, SOC stocks (SOCS), aggregate distributions, and OC fractions within aggregates were measured under five typical land-use types (cropland, grassland, shrubland, plantation forest, and natural forest) in a karst faulted basin, China. Land-use type had distinct effects on SOCS in the topsoil (0–10 cm) and along the soil profile (0–60 cm), and the primary factors influencing SOCS varied with the soil horizons. Plantation forest had the highest SOCS (51.2 Mg C ha−1) in the topsoil, whereas the SOCS in shrubland (182.7 Mg C ha−1) was distinctively higher than those of other land-use types across the soil profile. Soil microbial biomass C and mean weight diameter were the major factors driving SOCS variation in the topsoil layer and the entire soil profile, respectively. OC content within macroaggregates (>0.25 mm) was significantly positively correlated with the SOC content of bulk soil, whereas only the mass proportion of large macroaggregates (>2 mm) showed a positive relationship with SOC. Additionally, mineral-associated OC (MAOC) was the dominant fraction of SOC and was abundant in macroaggregates. However, particulate OC (POC) within aggregates was relatively enriched in the topsoil and microaggregates. Considering the decomposition and distribution characteristics of OC fractions in different-sized aggregates, we suggest that the POC/MAOC ratios of macro- and microaggregates could respectively reflect aggregate capacity to sequestrate MAOC and POC across different land-use types. Overall, shrubland is the optimal land-use type for rocky desertification control in the karst fault basin, due to the protection of POC and MAOC within different-sized aggregates.
324. 题目: Combined effects of photoaging and natural organic matter on the colloidal stability of nanoplastics in aquatic environments
The transport and fate of nanoplastics (NPs) in aquatic environments are closely associated with their colloidal stability, which is affected by aging and natural organic matter (NOM) adsorption. This study systematically investigated the combined effects of photoaging and NOM (e.g. humic acids, HA; and a model protein, bovine serum albumin, BSA) on the aggregation kinetics of NPs (polystyrene, PS) in NaCl and CaCl2 solutions. Our results showed that photoaged NPs adsorbed less HA than pristine NPs due to weaker hydrophobic and π-π interactions. In return, HA showed weaker impacts on NPs’ stability after photoaging. Differently, photoaged NPs absorbed more BSA than pristine NPs due to stronger hydrogen bonding and electrostatic attraction. Thus, the inhibitory effects of BSA on the aggregation kinetics of NPs were enhanced after photoaging. Regarding the effects of NOM on the aging of NPs, our results showed that HA competed with NPs for photons and underwent photo-degradation. Subsequently, the destruction/reconstruction of adsorbed HA increased (in NaCl) or decreased (in CaCl2) the stability of NPs. Notably, light radiation-induced flocculation of BSA molecules, which wrapped and integrated NPs and lead to their destabilization. Overall, this study provided new insights into the aggregation behavior of NPs in aquatic systems, which have significant implications for predicting the transport and fate of NPs in complex real-world environments.
325. 题目: Application of predictor variables to support regression kriging for the spatial distribution of soil organic carbon stocks in native temperate grasslands
As the main component of terrestrial carbon pool, soil organic carbon (SOC) is vital to soil fertility and biogeochemical cycle. Quantifying the spatial distribution of regional SOC stocks (SOCS) provides critical support for climate change and food security decisions. Our aim was to explore the optimal interpolation method to improve the accuracy of spatial prediction of SOCS in temperate grasslands.
Materials and methods
To support such research, we performed soil sampling to depths of 0 to 20 and 20 to 30 cm throughout the Hulun Buir grassland of Inner Mongolia. We compared prediction of the spatial patterns of SOCS using regression kriging (RK) and ordinary kriging (OK). We used topographic factors, climate variables, satellite data (the normalized-difference vegetation index (NDVI)), and soil texture as predictors in the RK method.
Results and discussion
SOCS was significantly positively correlated with precipitation, NDVI, topographic variables, and clay content, but negatively correlated with temperature and sand content. NDVI explained more than 40% of the SOCS spatial variation and was the dominant factor. Geostatistical analysis showed strong and moderate spatial dependence of SOCS in the 0–20- and 20–30-cm soil layers, respectively. The RK and OK soil pools to a depth of 30 cm were 607.28 and 559.46 Tg, respectively.
Compared with OK, the RK method improved the SOCS prediction accuracy by 20.4, 30.1, and 23.9% for soil depths of 0–20, 20–30, and 0–30 cm, respectively. Our findings suggest that OK may be acceptable where the environmental conditions are homogeneous, but that RK performs better in heterogeneous areas.
326. 题目: The remediation of di-(2-ethylhexyl) phthalate-contaminated sediments by water hyacinth biochar activation of calcium peroxide and its effect on cytotoxicity
The presence of di-(2-ethylhexyl) phthalate (DEHP) in the aquatic systems, specifically marine sediments has attracted considerable attention worldwide, as it enters the food chain and adversely affects the aquatic environment and subsequently human health. This study reports an efficient carbocatalytic activation of calcium peroxide (CP) using water hyacinth biochar (WHBC) toward the efficient remediation of DEHP-contaminated sediments and oﬀer insights into biochar-mediated cellular cytotoxicity, using a combination of chemical and bioanalytical methods. The pyrolysis temperature (300–900 °C) for WHBC preparation significantly controlled catalytic capacity. Under the experimental conditions studied, the carbocatalyst exhibited 94% of DEHP removal. Singlet oxygen (1O2), the major active species in the WHBC/CP system and electron-rich carbonyl functional groups of carbocatalyst, played crucial roles in the non-radical activation of CP. Furthermore, cellular toxicity evaluation indicated lower cytotoxicity in hepatocarcinoma cells (HepG2) after exposure to WHBC (25–1000 μg mL−1) for 24 h and that WHBC induced cell cycle arrest at the G2/M phase. Findings clearly indicated the feasibility of the WHBC/CP process for the restoration of contaminated sediment and contributing to understanding the mechanisms of cytotoxic effects and apoptotic of carbocatalyst on HepG2.
327. 题目: Enhanced removal of fluoroquinolone antibiotics by peroxydisulfate activated with N-doped sludge biochar: performance, mechanism and toxicity evaluation
N-modified sludge-derived biochar (N-SDBC) was prepared and then used for activation of peroxydisulfate (PDS) to degrade fluoroquinolone antibiotics (FQs). Seven commonly used FQs were degraded by N-SDBC/PDS effectively, with the rate constants from 0.131 min-1 to 0.505 min-1. Scavenging experiments combined with electron paramagnetic resonance (EPR) confirmed that 1O2 was the dominated reactive species, and the radicals SO4•- and •OH played minor roles. In-depth study revealed that the graphite-N and Fe0 on the surface of N-SDBC were the main active sites for PDS activation. The elevated N precursors and calcination temperature enhanced the yields of graphite-N and Fe0. Products analysis indicated enrofloxacin degradation by 1O2 with the fragmentation of the piperazine ring, the disconnection of the quinolone ring, decarboxylation, and defluorination. The toxicity assessment by Escherichia coli and ECOSAR showed that the biological toxicity of ENR could be reduced after treating by N-SDBC/PDS. The application in surface water and wastewater samples demonstrates the efficiency of FQs removal by N-SDBC/PDS.
328. 题目: Biochar decreases and nitrification inhibitor increases phosphorus limitation for microbial growth in a wheat-canola rotation
Agricultural management practices affect microbial populations and ecoenzymatic activities; however, the effect of these practices on ecological stoichiometry relating the elemental ratio of resources to microbial biomass is poorly understood. In a 2-year field study, we assessed the effects of biochar and nitrapyrin (a commonly used nitrification inhibitor (NI)) on the ecological stoichiometry and microbial nutrient limitation in a wheat (Triticum aestivum L.)-canola (Brassica juncea L.) rotation. This study used a 3 × 2 factorial design that included two treatments: (i) biochar with three levels: no biochar addition (BC0), and biochar added at 10 (BC10) and 20 t ha−1 (BC20), and (ii) NI with two levels: without (NI0) and with NI (NI1). Soil microbial biomass carbon (C), nitrogen (N) and phosphorus (P) were increased by biochar application, regardless of the application rate, but were not affected by NI application. Biochar increased and NI decreased β-1,4-glucosidase, β-1,4-N-acetyl glucosaminidase and acid phosphatase (P < 0.05) with subsequent changes in ecoenzymatic stoichiometry. Ecoenzymatic stoichiometry analysis showed microbial P limitation relative to N in the studied area irrespective of the treatment, with contrasting effects of biochar (decreasing) and NI (increasing) on the vector angle of ecoenzymatic stoichiometry (P = 0.037 and 0.043, respectively). Biochar applied at 20 t ha−1 decreased the threshold elemental ratio of C:P at which microbial growth switches between nutrient and C limitations, suggesting a shift towards C relative to nutrient (P) limitation. This study concludes that biochar produced from manure compost can be useful in increasing microbial growth by alleviating P limitations in a wheat-canola rotation.
329. 题目: Ball milling Fe3O4@biochar cathode coupling persulfate for the removal of sulfadiazine from water: effectiveness and mechanisms
This study used biochar as the substrate of the electrodes, and a simple synthetic process (ball milling) was adopted to prepare the Fe3O4@biochar cathode enhanced coupled system of electrochemistry-potassium persulfate to achieve the efficient removal of sulfadiazine. Studies showed that the cracking temperature of biochar and the iron-to-carbon mass ratio determined the catalytic performance of cathodes. In addition, ball milling increased the surface functional groups of biochar and promoted the dispersion of Fe3O4 on biochar, leading to increased active sites on the Fe3O4@biochar cathode surface. It was found that SDZ and TOC removal rates reached 95.3% and 86.9% in the coupled system of electrochemical-persulfate with SDZ concentration of 10 mg/L, initial pH0 of 7, PDS concentration of 4 mM, current density of 30 mA/cm2, and electrode plate spacing of 4 cm. Also, this system showed excellent removal of sulfadiazine in actual water bodies. The quenching experiments and electron paramagnetic resonance spectra revealed that free radicals and non-radicals were involved in removing sulfadiazine, with free radicals (SO4•−) being the dominant pathway. Four main degradation pathways were proposed based on the intermediates of sulfadiazine. In conclusion, Fe3O4@biochar cathode enhanced coupled system of electrochemical-persulfate could be regarded as an efficient cleaning technology to provide a method for the removal of intractable organic pollutants.
330. 题目: Atmospheric Black Carbon Loadings and Sources over Eastern Sub-Saharan Africa Are Governed by the Regional Savanna Fires
331. 题目: Potential influence of fine aerosol chemistry on the optical properties in a semi-arid region
The current understanding regarding the potential influence of aerosol chemistry on the optical properties does not satisfy accurate evaluation of aerosol radiative effects and precise determination of aerosol sources. We conducted a comprehensive study of the potential influence of aerosol chemistry on the optical properties in a semi-arid region based on various observations. Organic matter was the main contributor to the scattering coefficients followed by secondary inorganic aerosols in all seasons. We further related aerosol absorption to elemental carbon, organic matter, and mineral dust. Results showed that organic matter and mineral dust contributed to >40% of the aerosol absorption in the ultraviolet wavelengths. Therefore, it is necessary to consider the absorption of organic matter and mineral dust in addition to that of elemental carbon. We further investigated the potential influence of chemical composition, especially of organic matter and mineral dust on the optical parameters. Mineral dust contributed to higher absorption efficiency and lower scattering efficiency in winter. The absorption Ångström exponent (AAE) was mostly sensitive to organic matter and mineral dust in winter and spring, respectively; it was relatively high (i.e., 1.68) in winter and moderate (i.e., 1.42) in spring. Unlike in the other seasons, mineral dust contributed to higher mass absorption efficiency in winter. This work reveals the complexity of the relationship between aerosol chemistry and optical properties, and especially the influence of organic matter and mineral dust on aerosol absorption. The results are highly important regarding both regional air pollution and climate.
332. 题目: Evidence from molecular marker and FT-ICR-MS analyses for the source and transport of dissolved black carbon under variable water discharge of a subtropical Estuary
Dissolved black carbon (DBC) is the largest known refractory organic carbon pool in the ocean. However, processes in estuaries connecting rivers (a significant DBC source) and oceans are underexplored. We carried out two sampling campaigns in the Jiulong River estuary (JRE) and conducted a dissolved organic matter (DOM) mixing experiment. DBC was quantified by the benzenepolycarboxylic acid (noted as DBC-BPCA) method and characterized with Fourier transform ion cyclotron resonance mass spectrometry (noted as DBC-FT). The molecular formulae of DBC-FT in the JRE were also compared with that in soil and atmospheric deposition. Overall, DBC-BPCA was removed during seaward dispersion. Soil- and deposition-derived molecules were identified in the DBC-FT of the JRE, confirming deposition inputs to estuarine DBC for the first time. The salinity-dependent decrease in the intensity normalized modified aromatic index (AImod) of DBC-FT and in DBC-BPCA revealed that DBC composition and concentration were primarily controlled by mixing. However, photodegradation and particle adsorption/flocculation may play a role in removing DBC depending on the concentration of total suspended matter (TSM). The two campaigns showed that high discharge increased both riverine input and estuarine output of DBC. However, the removal patterns of DBC-BPCA were minimally influenced by discharge. We further estimated that approximately 20% DBC-BPCA was lost in this estuary annually. Future studies should investigate the transformation of DBC in coastal bays and the open ocean where the residence time is longer and the transparency of bulk water is higher.
333. 题目: Lack of nitrogen fertilizer rate effects on soil carbon and nitrogen supply capacity: evidence from a 10-year trial
Background and aims
The long-term effects of annual fertilizer nitrogen (N) applications on soil organic carbon (SOC) has important implications for cropping system productivity and climate change mitigation. To understand the impacts of N fertilizer on SOC and other soil properties in a corn-based cropping system, a 10-year (2009–2018) study was initiated in Elora, Ontario, Canada.
Corn was grown every year and crop management was held constant aside from the N rate applied. Plots received one of six long-term N rates (range: 30 to 260 kg-N ha-1). SOC (0–20 cm) was measured in every plot at the start and end of the study.
N fertilizer rate increased both grain yield (range: 5.6 to 11.0 Mg ha-1) and residue biomass (range: 5.0 to 7.6 Mg ha-1). Harvest index also increased significantly with N application (range: 0.49 to 0.55). Assuming a fixed harvest index would have overestimated residue returns. SOC increased by a similar amount after 10 years in all N rate treatments (mean: 4.5 Mg-C ha-1). Soil N supply capacity assessed at the end of the experiment was also unaffected by long-term N rate as measured by total soil N (0-20 cm), corn yield planted after trial conclusion (2019) and results from a 10-week incubation study.
N rate had no detectable effect on SOC, N supply capacity or aggregate stability after 10 years. While yield and residue C inputs did increase with N rate, assuming a constant harvest index of 0.5 would have overestimated actual residue C returns.
334. 题目: Hitchhiking into the Deep: How Microplastic Particles are Exported through the Biological Carbon Pump in the North Atlantic Ocean
335. 题目: Dynamics of soluble soil organic matter in Mediterranean maize-based forage system under organic and mineral fertilization
In Nitrate Vulnerable Zones (NVZ), the impact of animal effluent management on soil fertility is essential. A three-year study was carried out in a NVZ (Arborea, Central-western Sardinia, Italy), aiming to analyze the effect of different fertilization systems on soluble and total soil organic matter (SOM) within a silage maize-hay crop cropping system on sandy soil (Oxyaquic Xeropsamment). Four types of fertilization systems were compared: (i) cattle manure; (ii) cattle slurry; (iii) mineral; (iv) slurry + mineral. The water-extractable C and N content (WEC and WEN) from the topsoil (0–20 cm layer, the Ap1 horizon), the dissolved carbon (DC) and the dissolved nitrogen (DN) of the soil solution collected by disk lysimeters placed along the soil profiles, and the C content at the beginning and at the end of the experiment were determined.
The seasonal dynamics of WEC in the topsoil seemed mainly associated with the timing of the fertilizer distribution. In the topsoil, WEC was larger under slurry than under mineral treatment. The DC was rather low in the deeper soil layers and did not show any variation due to the fluctuations of fertilizer distribution that were seemingly influenced by the groundwater table. The fertilization systems influenced the soil C inputs and, in turn, the SOM content. Manure promoted a higher C stock in the deeper soil layers among the organic fertilizers. However, the hay crop added with manure and slurry showed lower crop residues and, thus, C input than that added with mineral fertilizer. This result suggests that the management of these organic fertilizers should carefully consider their impact on the overall productivity of the studied cropping system in Mediterranean NVZ to avoid a potential limitation for soil C accumulation in the long term.
336. 题目: Spatiotemporal pattern of ecosystem respiration in China estimated by integration of machine learning with ecological understanding
337. 题目: Integrating Biochar, Bacteria, and Plants for Sustainable Remediation of Soils Contaminated with Organic Pollutants
338. 题目: Humification improvement by optimizing particle size of bulking agent and relevant mechanisms during swine manure composting
For purpose of clarifying the impact on particle size of bulking agents on humification and relevant mechanisms, different length (<2 cm, 2cm, 5cm, 10 cm) of branch and straw were blended with swine manure individually for 100 days aerobic composting. Results demonstrated that, 2 cm and 5 cm of branch and straw promoted the highest degradation of DOC by 41.49% and 58.42%, and increase the humic substances by 23.81% and 55.82% in maturity stage, respectively, compared with other treatments. As shown in microbial consequence, the maximum relative abundance of humus funguses increased by 99.55% and 99.92% at phylum, and 98.95% and 99.24% at genus in 2 cm and 5cm of branch and straw treatment, thus verifying the result in variation of humus content. In a word, particle size could result in obvious impact on humification, and the optimized size were about 2 cm and 5 cm of branch and straw.
339. 题目: A RUpture-Based detection method for the Active mesopeLagIc Zone (RUBALIZ): A crucial step toward rigorous carbon budget assessments
340. 题目: Singlet Oxygen Seasonality in Aqueous PM10 is Driven by Biomass Burning and Anthropogenic Secondary Organic Aerosol