201. 题目: Exploring metal(loid)s dynamics and bacterial community shifts in contaminated paddy soil: Impact of MgO-laden biochar under different water conditions
In this study, a soil incubation experiment was conducted to explore the influence MgO-treated corn straw biochar (MCB) on the bioavailability and chemical forms of cadmium (Cd), lead (Pb), and arsenic (As), alongside the impact on the bacterial community within paddy soil subjected to both flooded and non-flooded conditions. Raw corn straw biochar (CB) served as the unmodified biochar control, aiding in the understanding of the biochar's role within the composite. The results showed that even at a minimal concentration of 0.5 %, MCB exhibited higher effectiveness in reducing the bioavailability of Pb and Cd compared to 1 % CB. In non-flooded conditions, 0.5 % MCB reduced the bioavailable Pb and Cd by 99.7 % and 87.4 %, respectively, while NaH2PO4-extracted As displayed a 14.5 % increase. With increasing MCB concentrations (from 0.5 % to 1.5 %), soil pH, DOC, EC, available phosphorus, and bioavailable As increased, while bioavailable Pb and Cd exhibited declining tendencies. Flooding did not notably alter MCB's role in reducing Pb and Cd bioavailability, yet it systematically amplified As release. Heavy metal fractions extracted by acetic acid increased in the MCB groups under flooding conditions, especially for As. The inclusion of 0.5 % MCB did not noticeably affect bacterial diversity, whereas higher doses led to reduced diversity and substantial changes in community composition. Specifically, the groups with MCB showed an increase in the Bacteroidetes and Proteobacteria phyla, accompanied by a decrease in Acidobacteria. These alterations were primarily attributed to the increased pH and EC resulting from MgO hydrolysis. Consequently, for Pb/Cd stabilization and soil bacterial diversity, a low dosage of MgO-treated biochar is recommended. However, caution is advised when employing MgO-treated biochar in soils with elevated arsenic levels, particularly under flooded conditions.
202. 题目: Potential mechanism of biochar enhanced degradation of oxytetracycline by Pseudomonas aeruginosa OTC-T
Extensive use of oxytetracycline (OTC) and the generation of its corresponding resistance genes have resulted in serious environmental problems. Physical-biological combined remediation is an attractive method for OTC degradation because of its high remediation efficiency, stability, and environmental friendliness. In this study, an effective OTC-degrading strain identified as Pseudomonas aeruginosa OTC-T, was isolated from chicken manure. In the degradation experiment, the degradation rates of OTC in the degradation systems with and without the biochar addition were 92.71–100 % and 69.11–99.59 %, respectively. Biochar improved the tolerance of the strain to extreme environments, and the OTC degradation rate increased by 20.25 %, 18.61 %, and 13.13 % under extreme pH, temperature, and substrate concentration conditions, respectively. Additionally, the degradation kinetics showed that biochar increased the reaction rate constant in the degradation system and shortened the degradation period. In the biological toxicity assessment, biochar increased the proportion of live cells by 17.63 % and decreased the proportion of apoptotic cells by 58.87 %. Metabolomics revealed that biochar had a significant effect on the metabolism of the strains and promoted cell growth and reproduction, effectively reducing oxidative stress induced by OTC. This study elucidates how biochar affects OTC biodegradation and provides insights into the future application of biochar-assisted microbial technology in environmental remediation.
203. 题目: Evaluation of Per- and Polyfluoroalkyl Substances Leaching from Biosolids and Mitigation Potential of Biochar through Undisturbed Soil Columns
204. 题目: Role of KOH-activated biochar on promoting anaerobic digestion of biomass from Pennisetum gianteum
Pennisetum giganteum is a promising non-food crop feedstock for biogas production due to its high productivity and bio-methane potential. However, the accumulation of volatile fatty acids (VFA) usually restricts the conversion efficiency of P. giganteum biomass (PGB) during anaerobic digestion (AD). Here, the role of KOH-activated biochar (KB) in improving the AD efficiency of PGB and the related mechanisms were investigated in detail. The results revealed that KB exhibited excellent electrical conductivity, electron transfer capacity and specific capacitance, which might be related to the decrease in the electron transfer resistance after adding KB to the AD process. In addition, the KB addition not only reinforced metabolisms of energy and VFAs but also promoted the conversion of VFAs to methane, leading to a 52% increase in the methane production rate. Bioinformatics analysis showed that Smithella and Methanosaeta were key players in the KB-mediated AD process of PGB. The stimulatory effect of methanogenesis probably resulted from the establishment of direct interspecies electron transfer (DIET) between VFA-oxidizing acetogens (e.g., Smithella) and Methanosaeta. These findings provided a key step to improve the PGB-based AD process.
205. 题目: Effect of long-term straw return on organic matter transformation by hydroxyl radical during paddy soil oxygenation
The generation of hydroxyl radicals (OH) mediated by Fe(II) has drawn increasing amounts of attention due to its significant role in the transformation of soil organic carbon (SOM) during redox fluctuations in paddy soil. This study further examined the effect of long-term (since 1984) straw return on Fe(II) on driving OH formation and SOM transformation upon paddy soils oxygenation. We found that long-term straw return could inhibit the OH and CO2 production in abiotic processes. The OH production decreased from 190.4 to 133.4 µM as the straw return amount increased from 0 to 19.16 t·hm−2·year−1. Moreover, 14.7–38.6 % of the CO2 production was associated with OH during oxygenation. By combining radical quenching and OM extraction, we determined that straw return could increase O2 reduction to H2O2 through a two-electron transfer pathway. Based on chemical extraction, Mössbauer spectra and multilinear regression model, we demonstrated that straw return resulted in more active Fe(II) species that controls the OH production. The results of 3DEEMs and FT-ICR MS showed that oxidative transformation can be accomplished by the introduction of OH to aromatic structures or olefins through ring opening and hydroxylation mechanisms. And OM at high straw return concentrations was likely oxidized by OH into bioavailable aliphatic compounds. Therefore, this study highlights the underappreciating effects of long-term straw return on Fe(II) oxidation in driving OH generation and SOM transformation in paddy soil redox fluctuation events.
206. 题目: Constraints on mineral-associated and particulate organic carbon response to regenerative management: carbon inputs and saturation deficit
Regenerative management has potential to increase soil organic carbon (SOC), which will be crucial for mitigating climate change and improving soil health. Distinct fractions of SOC, particulate organic carbon (POC) and mineral-associated organic carbon (MAOC), have been posited as having contrasting responses to regenerative management. The POC response has been proposed as a leading indicator of total SOC response, whereas MAOC response has been seen as eventually limiting SOC response due to its saturation behavior. We explored these and linked expectations of SOC, POC and MAOC response by leveraging multiple datasets of regenerative management with cover crops or perennial crops as contrasted with conventional management (n = 42 sites). Across sites, POC as a percentage of SOC was on average 19%. Regenerative management increased both POC and MAOC but increases in POC were smaller and narrower (0.78 ± 0.26 g C kg soil-1) than increases in MAOC (1.41 ± 0.80 g C kg soil-1). Changes in POC were only weakly correlated with changes in SOC (p < 0.001 but R2 = 0.11), revealing that absolute changes in POC at any timepoint should not be taken as indicative of total SOC responses. The MAOC response made up the majority of SOC response at 58% of sites. Changes in POC and MAOC with regenerative management were also not related (p = 0.72), indicating that comprehensive assessment of POC and MAOC is needed to understand SOC accumulation under regenerative management. Increases in POC were explained by annual average of increase in root C inputs with regenerative management, suggesting a limited ability for the current portfolio of regenerative management practices to increase POC, even when implemented over decadal timescales. In contrast, increases in MAOC were partially explained by cumulative-for-the-trial increases in root C inputs and were not clearly constrained by silt + clay-estimated saturation deficit. Our results indicate that the increase of MAOC storage in agricultural soils is not limited by saturation but rather by the extent to which root C inputs can be augmented, and that increasing POC storage will require novel practices to overcome current limitations on POC accumulation.
207. 题目: Wheat straw biochar as an additive in swine manure Composting: An in-depth analysis of mixed material particle characteristics and interface interactions
In recent research, biochar has been proven to reduce the greenhouse gases and promote organic matter during the composting. However, gas degradation may be related to the microstructure of compost. To investigate the mechanism of biochar additive, composting was performed using swine manure, wheat straw and biochar and representative solid compost samples were analyzed to characterize the mixed biochar and compost particles. We focused on the microscale, such as the particle size distributions, surface morphologies, aerobic layer thicknesses and the functional groups. The biochar and compost particle agglomerations gradually became weaker and the predominant particle size in the experiment group was < 200 μm. The aerobic layer thickness (Lp) was determined by infrared spectroscopy using the wavenumbers 2856 and 1568 cm−1, which was 0–50 μm increased as composting proceeded in both groups. The biochar increased Lp and facilitated oxygen penetrating the compost particle cores. Besides, in the biochar-swine manure particle interface, the aliphatic compound in the organic components degraded and the content of aromaticity increased with the composting process, which was indicated by the absorption intensity at 2856 cm−1 decreasing trend and the absorption intensity at 1568 cm−1 increasing trend. In summary, biochar performed well in the microscale of compost pile.
208. 题目: Interrelation between extracellular polymer substances (EPSs) and MPs in an MBR
Nowadays, microplastics (MPs), as ubiquitous pollutants in aquatic ecosystems, present a major emerging threat. Wastewater treatment plants (WWTPs) are considered a hotspot of MP contamination. In this context, membrane bioreactors (MBRs), which combine conventional activated sludge processes with filtration, serve as an effective technology to remove MPs from wastewater. One of the main factors that affect MBR performance is the amount and composition of extracellular polymeric substances (EPSs) in the mixed liquor (ML). In previous studies carried out at lab-scale with model MPs, it has been found that the presence of MPs in wastewater treatment processes affect the EPS characteristics. In this work, the inter-relationship between EPSs and MPs has been investigated in a MBR at an industrial scale. Samples of the ML were taken from a WWTP during a six-month period and EPSs and MPs were analysed. It was observed that the higher the concentration of MPs, the higher the amount of EPSs were secreted by microorganisms, which seems to indicate that MPs act as an environmental stressor. Additionally, ML samples were centrifuged and the retention of MPs in the centrifuged solid (CS), which mainly depends on the size and morphology of MPs, was evaluated in relation to the amount and composition of EPSs. Remarkably, the concentration of humic acids showed a linear correlation with respect to the percentage of MPs retained in the CS. According to this, a possible mechanism based on hydrophobic interactions has been proposed as being responsible for the retention of MPs in sludge flocs.
209. 题目: Synergistic effects of Fe-based nanomaterial catalyst on humic substances formation and microplastics mitigation during sewage sludge composting
In this study, a novel Fe-based nanomaterial catalyst (Fe0/FeS) was synthesized via a self-heating process and employed to explore its impact on the formation of humic substances and the mitigation of microplastics. The results reveal that Fe0/FeS exhibited a significant increase in humic acid content (71.01 mg kg−1). Similarly, the formation of humic substances resulted in a higher humification index (4.91). Moreover, the addition of Fe0/FeS accelerated the degradation of microplastics (MPs), resulting in a lower concentration of MPs (9487 particles/kg) compared to the control experiments (22792 particles/kg). Fe0/FeS significantly increased the abundance of medium-sized MPs (50–200 μm) and reduced the abundance of small-sized (10–50 μm) and large-sized MPs (>1000 μm). These results can be attributed to the Fe0/FeS regulating the ▪OH production and specific microorganisms to promote humic substance formation and the degradation of MPs. This study proposes a feasible strategy to improve composting characteristics and reduce contaminants.
210. 题目: Machine learning assisted adsorption performance evaluation of biochar on heavy metal
Heavy metals (HMs) represent pervasive and highly toxic environmental pollutants, known for their long latency periods and high toxicity levels, which pose significant challenges for their removal and degradation. Therefore, the removal of heavy metals from the environment is crucial to ensure the water safety. Biochar materials, known for their intricate pore structures and abundant oxygen-containing functional groups, are frequently harnessed for their effectiveness in mitigating heavy metal contamination. However, conventional tests for optimizing biochar synthesis and assessing their heavy metal adsorption capabilities can be both costly and tedious. To address this challenge, this paper proposes a data-driven machine learning (ML) approach to identify the optimal biochar preparation and adsorption reaction conditions, with the ultimate goal of maximizing their adsorption capacity. By utilizing a data set comprising 476 instances of heavy metal absorption by biochar, seven classical integrated models and one stacking model were trained to rapidly predict the efficiency of heavy metal adsorption by biochar. These predictions were based on diverse physicochemical properties of biochar and the specific adsorption reaction conditions. The results demonstrate that the stacking model, which integrates multiple algorithms, allows for training with fewer samples to achieve higher prediction accuracy and improved generalization ability.
211. 题目: Pulsed inputs of high molecular weight organic matter shift the mechanisms of substrate utilisation in marine bacterial communities
212. 题目: Controls of Mineral Solubility on Adsorption-Induced Molecular Fractionation of Dissolved Organic Matter Revealed by 21 T FT-ICR MS
213. 题目: Soil Humic Acid Stimulates Potentially Active Dissimilatory Arsenate-Reducing Bacteria in Flooded Paddy Soil as Revealed by Metagenomic Stable Isotope Probing
214. 题目: Influence of Divalent Cation Inhibition and Dissolved Organic Matter Enhancement on Phenol Oxidation Kinetics by Manganese Oxides
215. 题目: Strengthening effect of mixed biochar on microbial remediation of PAHs-contaminated soil in cold areas
The content of PAHs in surface soils of northeastern China is high, which causes long-term soil pollution and potential harm to human health. Influenced by the temperature, the soil in the northeast region is characterized by a long-term freeze–thaw seasonal climate, which greatly affects the process of soil remediation work. Therefore, it is necessary to study the remediation strategies of PAHs in low-temperature soils. Our group discovered that the combination of cold-tolerant fungi and bacteria was effective in degrading soil PAHs. However, we are required to further explore the choice of immobilization vector.
Materials and methods
In this study, four different types of biochar (C300, C500, B300, B500) were prepared at 300 °C and 500 °C using corn cob and wheat straw of industrial and agricultural waste as precursors. We then used the cross-mixing of these four types of biochar as the carrier for Pseudomonas sp. S4 and Mortierella alpina J7, which are bacteria capable of degrading PAHs. We used the adsorption immobilization method to prepare the repair materials for PAHs degradation mixed bacteria.
Results and discussion
Through comparison, the low-temperature and high-temperature mixed biochar (C300 + B500) was selected as the carrier. The results showed that mixed biochar immobilized degrading bacteria are the most effective in degrading Phe and Pyr in soil and their degradation effect was related to the mixing ratio. After 30 days of remediation at 15 °C, the best remediation effect was add immobilized mixed fungicide agent, mix biochar 1:2 using 0.67% C300 and 1.34% B500 (CBJ 1:2).
Studies have shown that a mixture of low- and high-temperature biochar is a more promising strategy when used in combination with PAHs-degrading bacteria.
216. 题目: Soil organic carbon data comparison after 85 years and new 13C/12C compositions: The case study of the Ferrara province (Northeastern Italy)
217. 题目: Sources and high burial efficiency of fossil organic carbon in small bays and implication for coastal carbon cycle
Coastal seas receive and store large amounts of organic carbon (OC) from land and ocean, thereby playing a crucial role in the global carbon cycle. Understanding factors that influencing OC sources and burial efficiencies in coastal areas have been challenging. We selected the Jiaozhou Bay (JZB) and its surrounding rivers heavily affected by human activities as a case study small bay. We presented bulk parameters of grain size, sediment surface area (SSA), TOC content and carbon isotopes (δ13Corg and Δ14Corg), terrestrial biomarkers (∑C27 + C29 + C31 n-alkanes) and marine biomarkers (brassicasterol and dinosterol) in surface sediments and suspended particulates. Our results showed low TOC and biomarker contents in the Dagu River Estuary from the west of the JZB associated with coarse sediments and lower SSA. To estimate the OC proportions, we applied a three-end member mixing model based on TOC δ13Corg and biomarker ratios and obtained the OC contribution from phytoplankton (average 52 %), soil (average 34 %) and wetlands (average 14 %). A transect from east to west of the JZB was selected to further assess the OC age composition based on radiocarbon isotopic (14C) measurements for a new perspective. The lower Δ14Corg values in the east revealed fossil OC contributions from human activities, such as petroleum pollutant inputs from sewage outlets. Based on a dual‑carbon isotope (δ13Corg and Δ14Corg) mass balance mixing model, the OC contributions were 40 %, 34 %, 14 %, 12 % from fossil carbon, phytoplankton, wetlands and soil, respectively. The very high burial efficiency of fossil OC in JZB (111 ± 19 %) indicated that small bays such as the JZB could be an important sedimentary carbon sink.
218. 题目: Efficient Removal of Cr(VI) from Wastewater by Magnetic Biochar Derived from Peanut Hull
The contamination of chromium (Cr(VI)) in groundwater threatens public health because of the industrial development being historically less supervised. To remove Cr(VI) from groundwater and other surface waters, a new FeCl3-modified magnetic biochar (MBPH550) was prepared from a waste peanut hull. The magnetic potential was to facilitate the separation of absorbent from the water phase. The removal efficiency, adsorption kinetics and isotherm models, and adsorption mechanism of Cr(VI) on MBPH550 were investigated. MBPH550 had a large specific surface of 243.23 m2/g and saturation magnetization of 5.65 emu/g. MBPH550 achieved a removal efficiency of Cr(VI) up to 92.2% ± 2.0%. Low pH favored the adsorption of Cr(VI). At pH 6.0, the adsorption of Cr(VI) on MBPH550 fits the Elovich kinetic model and Freundlich isothermal adsorption model, with an equilibrium adsorption capacity of 6.64 mg/g. In addition to the direct functional group coordination and precipitation on the surface of MBPH550, Cr(VI) was also reduced to Cr3+, Cr(OH)3, Cr2O3, and FeCr2O4, which were all deposited on the surface of MBPH550. MBPH550 could be a widely applied efficient adsorbent for removing Cr(VI) from wastewater, groundwater, and leachate of Cr-contaminated soil.
219. 题目: Constructing transferable and interpretable machine learning models for black carbon concentrations
Black carbon (BC) has received increasing attention from researchers due to its adverse health effects. However, in-situ BC measurements are often not included as a regulated variable in air quality monitoring networks. Machine learning (ML) models have been studied extensively to serve as virtual sensors to complement the reference instruments. This study evaluates and compares three white-box (WB) and four black-box (BB) ML models to estimate BC concentrations, with the focus to show their transferability and interpretability. We train the models with the long-term air pollutant and weather measurements in Barcelona urban background site, and test them in other European urban and traffic sites. Despite the difference in geographical locations and measurement sites, BC correlates the strongest with particle number concentration of accumulation mode (PNacc, r = 0.73–0.85) and nitrogen dioxide (NO2, r = 0.68–0.85) and the weakest with meteorological parameters. Due to its similarity of correlation behaviour, the ML models trained in Barcelona performs prominently at the traffic site in Helsinki (R2 = 0.80–0.86; mean absolute error MAE = 3.90–4.73 %) and at the urban background site in Dresden (R2 = 0.79–0.84; MAE = 4.23–4.82 %). WB models appear to explain less variability of BC than BB models, long short-term memory (LSTM) model of which outperforms the rest of the models. In terms of interpretability, we adopt several methods for individual model to quantify and normalise the relative importance of each input feature. The overall static relative importance commonly used for WB models demonstrate varying results from the dynamic values utilised to show local contribution used for BB models. PNacc and NO2 on average have the strongest absolute static contribution; however, they simultaneously impact the estimation positively and negatively at different sites. This comprehensive analysis demonstrates that the possibility of these interpretable air pollutant ML models to be transferred across space and time.
220. 题目: Nanoscale Insights into the Interaction Mechanism Underlying the Adsorption and Retention of Heavy Metal Ions by Humic Acid