41. 题目: Priming effect of autochthonous organic matter on enhanced degradation of 17α-ethynylestradiol in water-sediment system of one eutrophic lake
Climate change and increasing eutrophication are expected to increase the release of autochthonous organic matter (OM) to sediments, where most contaminants are transformed or mineralized in freshwater lakes. This study sought to evaluate how cyanobacteria- and macrophyte-derived OM (COM and MOM) affected the microbial attenuation of 17α-ethinylestradiol (EE2) in the sediment from eutrophic Lake Taihu in China. In two months of water-sediment microcosm experiments, the input of COM and MOM both promoted EE2 degradation more strongly than humic acids, and the degradation efficiency was significantly and positively correlated with the cometabolism of increasing organic carbon in sediments (P < 0.001). The enhanced degradation was explained by responses of indigenous bacterial community to OM amendment as a priming effect. The immediate breakdown of biodegradable components such as proteinaceous substances in COM and MOM remarkably augmented the metabolic activity of bacteria in terms of the stimulated activity of extracellular enzymes including fluorescein diacetate and dehydrogenase, as well as the elevated production of proteins and polysaccharides in extracellular polymeric substances. In the meantime, the bacterial community composition was reshaped toward a more eutrophic state, leading to the clear upregulation of metabolic function genes of organic carbon and xenobiotics. Correlation-based network analysis further determined the strong facilitative coordination between the community members and the compositional variability of OM in the cometabolism. These results suggest that cyanobacterial blooms-dominated zones are potential hotspot areas for steroid estrogen attenuation, a finding of significance for the control and management of complex pollution in freshwater lakes.
42. 题目: Correlation between the ratio of 5-methyl hexamethylated to pentamethylated branched GDGTs (HP5) and water depth reflects redox variations in stratified lakes
Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are potentially valuable biomarkers for paleoclimatic and paleoenvironmental studies. However, multiple factors controlling their variations in lake sediments hamper the widespread application of brGDGT-based proxies. Here we investigate brGDGTs in water column suspended particulate matter (SPM) and surface sediments in a series of lakes with a wide range of depths from three main volcanic fields of northeastern China. The brGDGT distribution patterns from SPM and surface sediments of these lakes differ greatly from those of surrounding soils, indicating a predominant aquatic origin for brGDGTs. We find that the ratio of 5-methyl hexamethylated and pentamethylated brGDGTs with no cyclopentane rings (IIIa/(IIa+IIIa); designated as HP5) is strongly correlated with water depth. Re-examination of published brGDGT data from SPM samples in redox-stratified Lake Lugano reveals similar relationships, whereas such correlations are much weaker in Lake Superior which does not have an anoxic hypolimnion. Importantly, we find that there is strong correlation between HP5 and dissolved oxygen in water column of the redox-stratified lakes, suggesting that the observed apparent HP5–water depth correlation may be primarily attributed to depth-progressive shifts in the brGDGT-producing bacterial communities with different redox requirements (aerobic, facultative anaerobic, and anaerobic bacteria). Notably, brGDGT methylation indices (MBTʹ5ME and MBTʹ6ME) of surface sediments display poor correlations with air temperatures in our study lakes, calling for caution in applying MBTʹ5ME and MBTʹ6ME as temperature proxies in these lakes.
43. 题目: Identifying the spatial drivers and scale-specific variations of soil organic carbon in tropical ecosystems: A case study from Knuckles Forest Reserve in Sri Lanka
Soil organic carbon (SOC) is a key driver of ecosystem functioning and may also contribute to climate change mitigation through the sequestration of carbon. Therefore, having an understanding of the key drivers of SOC may inform management changes that will improve ecosystem function and climate change mitigation. The selected study area is ranged from montane forests to tropical grasslands. Extensive soil sampling (0–0.15 m and 0.15–0.30 m) was undertaken across this region to inform our knowledge about key drivers of SOC at different spatial scales. Initially spatial modelling was carried out using spatial linear mixed modelling approach using a variety of environmental covariates. The model had a Lin's concordance correlation coefficient value of 56–60%, and indicated that SOC was predominately influenced by vegetation type and elevation, although the sub-surface (0.15–0.30 m) SOC was influenced by slope and wetness index. Further, four spatial transects with 100 m sampling interval were extracted from the digital maps representing the study area and empirical mode decomposition (EMD) analysis was carried out to examine the scale specific variability of SOC stocks. The EMD, a mathematical analysis, separates dominant frequencies within a spatial/temporal series representing variability created by various underlying processes operating at different scales into a finite number of scale components or intrinsic mode functions (IMFs). Decomposition of SOC spatial series for the considered transects resulted up to 7 IMFs. The scale components with lower IMF numbers separated higher frequency oscillations, whereas higher IMF numbers separated lower frequency oscillations, which is the representative of smaller and larger scale processes, respectively. Spectral analysis was performed to identify the scales of IMFs and the correlation analysis was carried out with different environmental covariates to identify the dominant controlling factors at different depths. Majority of the large-scale variations (e.g. 2037–8149 m for IMF's 6 for depth interval 0–0.15 m for transect 1–4) were attributed to the elevation and climatic factors controlling the forest type, while small-scale (e.g. 69–118 m for IMF's 1 for depth interval 0–0.15 m for transect 1–4) variations were more attributed terrain derived attributes. Similar scales were identified for the depth 0.15–0.30 m. The scale-specific controlling factors at different locations and their relative controlling factors may help in selecting environmental covariates that enables us to model SOC more accurately rather than fitting one global model. The study provided firsthand information on baseline SOC stock values from a tropical forest ecosystem with six different vegetation types. The information revealed in this study will be useful in the conservation of tropical forests in the region and towards providing vital firsthand information to establishing a national carbon accounting system for land sector in the future.
44. 题目: Insight into the mechanism of persulfate activated by bone char: Unraveling the role of functional structure of biochar
Recently, biochar was frequently applied in catalysis field, and it has been regarded as an efficient carbon-rich material to degrade organic pollutants in water. Various functional structures of biochar (such as pore structure, oxygen-containing groups and, defects) have been reported to be valid in catalysis. Whereas the complexity of biochar structure and composition hinders the further exploration of specific functions of biochar. To address this problem, selective inactivation experiment was first involved to investigate the role of oxygen-containing groups in catalysis. In this study, swine bone derived biochar (BBC) was adopt as catalyst in persulfate (PS) activation system to degrade acetaminophen (ACT). Both non-radical and radical pathway worked in BBC/PS system. ACT could be completely degraded in 60 min, and the removal rate could reach 0.3111 min−1. The results showed that the ketone groups on the BBC were the primary active sites of PS/BBC system and it played a major role in non-radical pathway (electron transfer pathway), and it might act as the active sites to produce OH in BBC/PS system. Besides, the COOH and OH on BBC might be beneficial to radical pathway, which can help to generate OH and SO4−. Interestingly, residual hydroxyapatite and defects in BBC might be able to stimulate PS to produce O2− and 1O2. With the development of increasingly precise biochar synthesis techniques, these verdicts give evidence to further oriented synthesis of biochar.
45. 题目: Customised fabrication of nitrogen-doped biochar for environmental and energy applications
Global warming, environmental pollution, and energy shortage are causing severe environmental concerns for sustainable development. Conversion of various renewable biowastes into value-added carbon-based materials can be a promising option to alleviate these issues. The emergence of nitrogen (N)-doped biochar provides a versatile electroactive candidate suitable for environmental and energy applications. In this review, we scrutinise and highlight the customised production of N-doped biochars and their up-to-date applications in environmental remediation, energy storage, and biorefinery fields. With a comprehensive overview on the original precursor, the interspecies conversion, and the ultimate deactivation of various N-dopants in biochar-based carbocatalysis, their formation mechanisms, distinct electrochemical characteristics, fate in the environmental and energy applications, and electrochemical behaviour can be thoroughly analysed. Contemporary challenges that require to be addressed and perspectives on improving N-doping technique on biochar are articulated. Overall, this review helps to provide new insights into the customised production of N-doped biochar for its broader applications in sustainable carbocatalysis and green chemistry.
46. 题目: Thermodynamics of soil organic matter decomposition in semi‐natural oak (Quercus) woodland in southwest Ireland
47. 题目: Connecting land use−land cover and precipitation with organic matter biogeochemistry in a tropical river–estuary system of western peninsular India
Organic matter (OM) composition changed due to land use ─ land cover (LULC) and hydrology modification, has distinctive linkage towards sustainable environment management in tropical river systems. It is crucial in small river systems, which experience delay of freshwater flow to the estuaries due to headwater damming, also LULC alteration along the entire basin. In order to understand this fundamental linkage in tropical Zuari river-estuary (ZRE), we analyzed multi-proxy data of organic carbon to total nitrogen ratio (Corg/N), stable organic carbon isotope (δ13Corg) and lignin phenols measured in seasonally collected suspended particulate matter (SPM) and sediment samples. Results highlighted about moderate seasonality of OM tracers, with a significant effect of LULC alteration, which nevertheless a striking feature in monsoon-fed river-estuaries of peninsular India. Particulate Corg export from ZRE estimated to be 20 × 103 kg yr−1, was much lower as compared to tropical river-estuary systems elsewhere. OM fraction from vascular plant (mangroves) contributed to SPM and sediment was 15% and 40%, respectively, calculated using a Bayesian mixing calculation through Stable isotope analysis in R (SIAR). Presence of mudflat LULC in the estuarine region notably caused 20% decrease in Corg and 60% increase in lignin phenol (Λ8) as compared to their limits in upstream. This is although mudflat accounts only 3% of ZRE catchment. The degree of shifts in OM tracers highlights towards efficient entrapment, transformation and/or utilization of riverine OM in the mudflats of ZRE. Accelerated human induced LULC dampens the seasonality of OM characteristics and flow is highlighted through this study, which is essential towards sustainable environmental management practice in small rivers of India and World.
48. 题目: Adsorption–desorption behavior of benzobicyclon hydrolysate in different agricultural soils in China
Benzobicyclon is a systemic herbicide that was officially registered in China in 2018. The environmental behaviors of benzobicyclon hydrolysate (BH), the main metabolite and active product of benzobicyclon, remain poorly understood in paddy fields. Here, agricultural soil samples were collected from paddy fields in Jiangxi (Ferralsols), Shandong (Alisols), Hebei (Luvisols), Heilongjiang (Phaeozems), Zhejiang (Anthrosols), Sichuan (Gleysols), Hainan (Plinthosols), and Hubei (Lixisols) across China. The equilibrium oscillation method was used to study the adsorption–desorption behaviors of BH in the eight soils. The relationships between BH adsorption and soil physicochemical properties, environmental factors (temperature and initial solution pH), and other external conditions (addition of humic acid, biochar, and metal ions) were quantified. The adsorption–desorption parameters of BH in all soils were well fitted by the Freundlich model. The adsorption constant of BH varied between 0.066 and 4.728. The BH adsorption capacity decreased in the following order: Phaeozems > Alisols > Ferralsols > Lixisols > Plinthosols > Anthrosols > Luvisols > Gleysols. The Freundlich adsorption and desorption constants of BH were linearly positively correlated with soil clay content (R2 = 0.711 and 0.709; P = 0.009 and 0.009, respectively), organic carbon content (R2 = 0.684 and 0.672; P = 0.011 and 0.013, respectively), and organic matter content (R2 = 0.698 and 0.683; P = 0.010 and 0.011, respectively); however, their linear relationships with soil cation exchange capacity were not significant (R2 = 0.192 and 0.192; P = 0.278 and 0.278, respectively). The adsorption and desorption constants of BH had negative, albeit not significant, correlations with soil pH (R2 = 0.104 and 0.100; P = 0.437 and 0.445, respectively). The adsorption of BH by soil occurred spontaneously and was mainly based on physical adsorption. Either low or high temperature reduced the ability of the soil to adsorb BH. The addition of humic acid to the soil increased BH adsorption, while the addition of biochar increased the solution pH, resulting in decreased BH adsorption. Cation type and ionic strength also had strong effects on BH adsorption. With the exception of Phaeozems, BH exhibited intermediate or high mobility in the agricultural soils and thus poses risks to surface water and groundwater.
49. 题目: Dissolved organic matter composition and reactivity in Lake Victoria, the world's largest tropical lake
50. 题目: C:N:P stoichiometry and nutrient limitation of stream biofilms impacted by grassland degradation on the Qinghai-Tibet Plateau
51. 题目: Comparative study of lignin stabilizing mechanisms in soil aggregates at virgin mixed broadleaf-pine forest and secondary broadleaf forest at Changbai Mountain Nature Reserve, Northeast China
The variation of soil organic carbon (SOC) stability is independent of the amount of SOC in the soil. For predicting the conservation of soil carbon in different forest ecosystems, it is crucial to investigate the mechanisms of plant derived residues allocation and stabilization in soil aggregates in different forest ecosystems. The role of aggregate protection in SOC sequestration (using lignin as a biochemical indicator) requires understanding of the interaction of many factors. We studied aggregate proportion, SOC amount and lignin phenol contents in the soil fractions from 0–5, 5–10 and 10–20 cm layers in a virgin mixed broadleaf-Korean pine (BK) and secondary broadleaf Betula-Populus (BP) stands at Changbai Mountain Nature Reserve, Northeastern China. Macroaggregates had higher lignin contents compared to the bulk soil in both BK and BP. The SOC and lignin contents in bulk soil and aggregates obviously declined with soil deepening in the two stands. BK exhibited more protected lignin in aggregates compared to the same particles from BP. The results suggested that the aggregates have limited capability to sequestrate more carbon, which causes carbon loss in the soil particles with soil depth increment in the secondary broadleaf forest. Stable lignin sequestration was achieved via effective aggregate protection in BK, while lignin occlusion was mainly regulated by the importation of plant residues into the topsoil of BP.
52. 题目: Molecular-level characterization of biodegradable organic matter causing microbial regrowth in drinking water by non-target screening using Orbitrap mass spectrometry
53. 题目: Catalytic performance and mechanism of biochars for dechlorination of tetrachloroethylene in sulfide aqueous solution
Biochar (BC) has been investigated as a natural and economical activator to treat organic contamination. Compared with commercial carbon materials, BCs have a better prospect of large-scale application. For the first time, this study certified degradation of tetrachloroethene (PCE) in sulfide-containing aqueous solutions catalyzed by wormwood-based BCs pyrolyzed at 600 °C, 700 °C, and 800 °C (BC600, BC700, and BC800). Interestingly, BC800 could catalyze PCE dechlorination and form acetylene and chloride ion with over 99% nontoxic transformation in neutral and alkaline pH conditions. Furthermore, materials surface properties, BC dosages and sulfide concentrations were considered as limiting factors for dechlorination, and the last one had the strongest influence. XPS analysis demonstrated that catalytic ability of BC was attributed to pyridine nitrogen (N6) on surface, because C and O adjacent to N6 strongly favor nucleophilic reactions. These results evaluated the applicability of degrading toxic chlorinated alkenes mediated by natural carbon materials in sulfide-containing environment.
54. 题目: Biochar in soil mitigates dimethoate hazard to soil pore water exposed biota
Soil contamination is a worldwide problem urging for mitigation. Biochar is a carbonaceous material used as soil amendment that can immobilize chemical compounds, potentially turning them unavailable for soil biota. The aim of our study was to evaluate biochar's capacity to immobilize dimethoate in soil and, therefore, decreasing the toxicity to soil organisms. Two biochar application rates (2.5% and 5% w/w) were chosen to assess dimethoate potential immobilization, looking at changes in its toxicity to the collembolan Folsomia candida and the plant Brassica rapa upon soil amendment. Complementarily, chemical analyses were performed on soil pore water. Results showed that biochar may sorb and decrease dimethoate concentrations in soil pore water, influencing dimethoate bioavailability and consequent toxicity. Contrary to dimethoate solo impact on collembolans (LC50 0.69 mg kg−1, EC50 0.46 mg kg−1), their survival rate and offspring production were not affected by dimethoate when biochar was applied, regardless of application rate (LC50 and EC50 > 1.6 mg kg−1). Shoot length, fresh and dry weights of B. rapa were less affected by dimethoate upon biochar addition (EC50 values increase for all endpoints). Our study shows that biochar may contribute to decrease dimethoate bioavailability and toxicity to soil porewater exposed organisms.
55. 题目: A novel reactor combining anammox and Fenton-like reactions for the simultaneous removal of organic carbon and nitrogen at different organic carbon to nitrogen ratios
A Fenton-like reaction and anaerobic ammonium oxidation (anammox) were combined to construct a novel process named FenTaMox for removing nitrogen (N) and organic carbon (measured as chemical oxidation demand (COD)). Two columns were packed with iron-manganese-sepiolite, a catalyst that uses hydrogen peroxide (H2O2) to catalyze Fenton-like reactions, and inoculated with marine anammox bacteria. During the start-up, marine anammox medium was fed into both columns to acclimate the marine anammox bacteria to iron-manganese-sepiolite. Batch experiments revealed that the marine anammox bacteria were not affected by 60 mgL−1 of H2O2. Next, medium containing glucose and H2O2 was fed into one column as the FenTaMox treatment, while medium containing glucose but no H2O2 was fed into the other column as the control. At a COD/N of 4, FenTaMox exhibited higher removal efficiencies of N and COD compared with that of the control, suggesting the application of FenTaMox for organic carbon- and N- removal.
56. 题目: Processing of dissolved organic matter from surface waters to sediment pore waters in a temperate coastal wetland
Coastal wetlands are active transitional ecotones between land and ocean, and are considered as hot spots of organic matter processing within the global carbon cycle, which dissolved organic matter (DOM) plays a critical role. In this study, combined use of ultrahigh-resolution mass spectrometry (FT-ICR MS) and complementary optical techniques was conducted to assess the detailed molecular composition of DOM in the temperate Liaohe coastal wetland (LCW), NE China in respect to the differences in DOM composition from surface water to sediment pore water. Significant positive correlations between salinity and dissolved organic carbon (DOC) concentrations were observed in both surface waters and pore waters. Pore water DOM is generally characterized by lower protein-like fluorescence and biological index, but higher humification and humic-like fluorescent components than those in surface water DOM. Corresponding to the optical properties, FT-ICR MS measurements show that pore water DOM has higher proportions of heteroatoms, aromaticity index, O/C ratios, unsaturated aliphatics, and peptides, but lower average H/C ratios compared to surface water DOM across locations with different marsh plant species (rice (Oryza sativa), reed (Phragmites australis), Seablite (Suaeda Salsa)) and salinity (0.5 to 51.5 psu). The results suggest that selective preservation for polyphenols, lignin degradation intermediates (highly unsaturated compounds), and microbial resynthesis of heteroatomic compounds are involved in the processing of DOM from surface water to pore water, leading to the formation of higher molecular weight and sulfur-containing molecules. The abundant CHOS compounds could be related to the early diagenetic sulfurization of DOM in sediments. Our unique data set should provide new clues for a comprehensive understanding of the molecular dynamics of DOM in coastal wetlands.
57. 题目: Effects of different variables on photodestruction of perfluorooctanoic acid in self-assembled micelle system
Perfluoroalkyl substance (PFAS) is a class of anionic surfactants with superior stability in the environment. Due to the harmful health effect, PFASs have been listed as the priority controlled pollutants. Our recent study had developed a cationic surfactant induced ternary self-assembled micelle system to effectively degrade PFASs. In this study, using perfluorooctanoic acid (PFOA) as the model pollutant, we further investigated the effects of different variables on the degradation processes. According to the results of laser flash photolysis and dynamic light scattering, the degradation of PFOA was positively correlated with the chain length of the surfactants. While for double-chain surfactant, the steric effect might hinder the reaction. Our results also indicated that in the presence of high concentration of NaCl, the electrostatic attraction between Cl− and the positively charged micelle made the micelle structure loose and thus slightly reduced the degradation efficiency. Similarly, the presence of NOM could also affect the degradation process via regulating the micelle structure. Furthermore, the optimal degradation efficiency for PFOA was obtained at neutral pH by the compromise of hydrated electron yield and self-assembled micelle structure. This composite showed good adaptability under ambient conditions and would have great potential for treatment of industrial PFAS containing wastewater, e.g., in the ternary micelle system, 18.95 mg L−1 PFOA could be completely degraded within 8 h without any pretreatments.
58. 题目: Leachability of endocrine disrupting chemicals (EDCs) in municipal sewage sludge: Effects of EDCs interaction with dissolved organic matter
In this study, experiments were performed to assess the significance of dissolved organic matter (DOM) on the leachability of four common EDCs, i.e., bisphenol A (BPA), 17α-ethinylestradiol (EE2), progesterone (PGT) and testosterone (TST), in municipal sewage sludge (MSS) under landfill conditions. The DOM was derived from two sources: MSS (MDOM), and natural soil represented by organic matter obtained from the Suwannee River (NDOM). Fluorescence excitation-emission matrix quenching combined with parallel factor analysis was adopted to characterize the interaction properties between the EDCs and DOM. The accumulative leachability of the target EDCs ranged from 0.09% (PGT) to 3.8% (TST). In particular, the leaching of BPA, EE2 and TST followed S-shaped curves, while PGT exhibited continuous leaching potential in untreated MSS. With the introduction of DOM, (i) the leachability of BPA and EE2 increased to 13.4% and 61.6%, respectively, whereas those of PGT and TST declined by 61.3% and 45.8%, respectively, and (ii) BPA, EE2 and PGT no longer reached leaching equilibrium but the S-shaped leaching property of TST persisted. The differential effects of MDOM and NDOM at identical concentrations on the EDCs leachability increased with curing time. BPA, EE2 and PGT quenched the MDOM fluorophores attributed to aromatic protein-like components. The fluorescence quenching of NDOM by BPA, EE2 and PGT was centered on soluble microbial by-product-like and humic-like substances. Compared with PGT, EE2 and BPA had greater capability for binding with DOM components largely via hydrophobic interactions, whereas PGT preferentially interacted with the DOM hydrophilic functionalities through specific interactions. TST had no binding capability but displayed potentials competing for sorption sites with DOM moieties. Our findings suggested that the management of MSS increased the risk of environmental contamination by EDCs for a long duration and that DOM was a useful indicator to predict the migration and transport properties of EDCs.
59. 题目: New insights into spatiotemporal source apportionment of n-alkanes under mixed scenario: A pilot study on Lake Chaohu, China
N–alkanes are ideal molecular markers for the source apportionment of organic matter. However, the estimation of both biogenic and anthropogenic sources under mixed scenario using n–alkanes and their related proxies still remains an issue. In this study, we investigated spatiotemporal variations of n–alkanes in suspended particulate matter of Lake Chaohu for their source apportionment. Overall, Σ29 n–alkanes ranged from 324.1 to 113685 ng·L−1. C17H36 was the most abundant homologue and was followed by C18, C27 and C29 homologues. Carbon preference indexes (CPIs) in most samples (at least 85%) were < 3, indicating mixed sources of n–alkanes in Lake Chaohu. Therefore, biogenic and anthropogenic n–alkanes were separated by subtraction to avoid potential bias. Our results showed Σ biogenic and Σ anthropogenic n–alkanes ranged from 14.8 to 3531.6 ng·L−1 and 257.6 to 4938.5 ng·L−1, respectively. For biogenic n–alkanes, their carbon–chain distributions posed a preponderant peak at C17, indicating algae were the main contributors to biogenic n–alkanes in Lake Chaohu. Biogenic average chain length (ACLbio) was developed to quantify the contributions of different biogenic sources. We recommended ACLbio < 21 for algae dominance and ACLbio > 26 for terrestrial plant dominance. For anthropogenic n–alkanes, their carbon–chain distribution presented obviously spatiotemporal variations. The sources of anthropogenic n–alkanes in summer and winter were typical dominances of light petroleum and incomplete fossil fuel burning/heavy oil emission, respectively. New developed proxies, anthropogenic average chain length (ACLanthro) and the ratio of unit short– to long–carbon anthropogenic n–alkanes (L/H), are effective for quantifying the relative contributions of different anthropogenic sources. We recommend log10L/H > 0.5 and ACLanthro < 20.5 for light petroleum input dominance, log10L/H < −0.5 and ACLanthro > 26.5 for incomplete fossil fuel burning at high temperature/heavy oil emission dominance.
60. 题目: Size Matters: Nano-Biochar Triggers Decomposition and Transformation Inhibition of Antibiotic Resistance Genes in Aqueous Environments