1. 题目: Application of biochar activated persulfate in the treatment of typical azo pigment wastewater
With the increase of the azo pigment wastewater, it is necessary to seek an efficient and sustainable treatment method to address issues of damaging water ecosystems and human health. In this work, organic representing azo dye Acid Orange 7 (AO7), heavy metal representing hexavalent chromium (Cr(VI)), and inorganic representing ammonia nitrogen (NH4+-N) were selected to roughly simulate the azo pigment wastewater. The simultaneous decontamination of multi-target pollutants by 700 °C pyrolyzed peanut shell biochar (BC) with persulfate (PDS) was evaluated. The results showed that AO7, Cr(VI) and NH4+-N could finally reach 100%, 85% and 30% removal ratios separately in the BC/PDS/mixed pollutants system under certain basic conditions. Functional groups (hydroxyl groups (C–OH) and carboxylic ester/lactone groups (O–C=O)) were found by XPS as competing sites for adsorption and activation and were gradually consumed as the reaction proceeded. Combining a series of experiments results and EPR analysis, it was found that AO7 removal worked best and it relied on both the radical pathway (including SO4•−, •OH, O2−•, but not 1O2) and adsorption. Cr(VI) was mainly adsorbed and reduced by BC surface to form Cr(OH)3 and Cr2O3, and the remaining part could be reduced by O2−•, followed by •OH. NH4+-N was removed primarily by the radical same as AO7. Meanwhile, the three target pollutants have a co-competitive mechanism. Specifically, they competed for radicals and adsorption sites simultaneously, while the presence of AO7 and NH4+-N would consume the generated oxidizing radicals and further promote the removal of Cr(VI). The fixed-bed reactor simulated the continuous treatment of wastewater. Various anions (chloride (Cl−), nitrate (NO3−), carbonate (CO32−), and hydrogen phosphate (HPO42−)) interfered differently with the pollutant removal. These findings demonstrate a new dimension of BC potential for decontamination of azo pigment wastewater.
2. 题目: Soil organic matter contents modulate the effects of bacterial diversity on the carbon cycling processes
Bacterial diversity drives multifunctionality in ecosystems, including carbon cycling, while a comprehensive understanding of how carbon contents modulate microbial function through bacterial diversity is unknown. The exact extent of the contribution of organic matters contents to carbon cyling process will be investigated using a dilution-to-extinction methods in soils.
Materials and methods
We conducted a dilution-to-extinction experiment to manipulate the bacterial diversity in soils amended with five different organic matter contents. Meanwhile, the abundance and community structure of bacteria were detected by quantitative PCR and high-throughput sequencing, respectively. Furthermore, the dehydrogenase activity, cellulase enzyme activity and β-glucosidase enzyme activity were detected.
Results and discussion
The co-occurrence patterns of sensitive bacterial communities in the soil with 5 organic matter contents showed that organic matter content had a strong effect on sensitive bacterial network complexity. The degree of functional redundancy varied with soil organic matter contents, which was attributed to the interactions among organisms.
Soil carbon contents exerted a strong influence on ecosystem function, and bacterial diversity plays a predominant role in soil with low organic content. Our findings showed the contribution of bacterial diversity in modulating soil function and shed new light on the role of microbial groups in land restoration.
3. 题目: Efficient activation of persulfate by Nickel-supported cherry core biochar composite for removal of bisphenol A
In this study, low-cost and easily obtained biochar was chosen to prepare nickel-modified biochar materials (Ni/BC) through a one-step activation pyrolysis method. Characterization with X-ray diffraction, X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy proved the existence of Ni0 and NiO nanocrystals in Ni/BC catalyst. The optimal Ni0.5/BC exhibited excellent peroxymonosulfate (PMS) and peroxydisulfate (PDS) activation efficiency toward bisphenol A (BPA) degradation. The Ni0.5/BC (0.03 g) reacted with 1.0 g L−1 PMS or PDS could completely remove 20 mg L−1 BPA in 10 min with the first-order kinetic constants (k1) of 0.322 min−1 (PMS) and 0.336 min−1 (PDS). More importantly, the composite has better structural and functional attributes for the BPA degradation with universal applicability at wide pH and temperature range, proving as a better degradation mediator with high adaptation for numerous organic pollutants. Catalytic activity decreased slightly even after 4 cycles. Based on the quenching experiment and electron paramagnetic resonance, it was found that SO4•−, •OH and 1O2 were the dominant active species in BPA degradation process. Therefore, this work not only supplies a promising catalyst for the removal of organic contaminants, but also is beneficial for the further development of alternative catalysts for sulfate radical based advanced oxidation processes.
4. 题目: Humic Acids Derived from Lignocellulosic Biomass: Characterization and Utilizing for Environmental Applications
The goal of this research is to evaluate waste lignocellulosic materials for the production humic acid (HA) as a natural, low-cost, and effective adsorbent for heavy metals (Ni, Cr, and Cu) removal from aqueous medium. The fourier transform infrared (FTIR) spectroscopy, fluoresence spectroscopy, LC-ESI-TOF/MS, and stable carbon isotopes analysis were applied to compare the chemical structure of humic acids obtained from wheat straw (C3) and corn straw (C4). The adsorption efficiency of humic acids obtained from different lignocellulosic sources was investigated and compared to the commercial HA. The adsorption efficiency for Cu ions was almost 70% and the metal adsorption capacity of corn-HA is remarkably higher than commercial HA. Ni ions exhibited the lowest adsorption percentage for which the removal reached 21.0% with corn-HA. This work showed that lignocellulosic-derived humic acids are suitable adsorbent for heavy metals and can be used for cleaning of waters or other systems with low concentrations of metal ions.
5. 题目: Revisiting organic waste-source-dependent molecular-weight governing the characterization within humic acids liking to humic-reducing microorganisms in composting process
Humic acids (HAs) coupled with humic-reducing microorganisms (HRMs) can facilitate contaminants reduction. Molecular-weight (MW) of HA governs the chemical and HRMs behavior. However, MW of HAs with chemical characteristics linking to HRMs in different wastes composting have never been investigated. Results from the HPSEC-UV analysis showed that composting significantly increased weight-average molecular weight (Mw) of HA with a broad range from 675 Da to 27983 Da, and governing heterogeneous chemical characteristics. In proteinaceous composts, MW<4000 Da of HAs were greatly related to alkyl and carbonyl, while MW>20000 Da of HAs were presented by oxygen–nitrogenous functional groups, methyl, and alkyl groups. For cellulosic composts, MW<1500 Da and 4000–10000 Da of HAs were characterized by aliphatic ethers and aromatic groups. MW>20000 Da of HAs were constructed by phenols, methoxy and nitrogen functional groups. In lignocellulosic composts, MW>20000 Da of HAs were only characterized by aromatic groups. Furthermore, seven groups of HRMs adapted to the heterogeneous chemical characteristics within HAs ranked by MW were recognized. Consequently, the possible routes that composting properties response to the connections of HRMs-chemical structures-MW of HAs in proteinaceous, cellulosic and lignocellulosic composts were constructed, respectively. Our results can help to develop the fine classification-oriented approach for recycling utilization of organic wastes.
6. 题目: Secondary Mineral Formation and Carbon Dynamics during FeS Oxidation in the Presence of Dissolved Organic Matter
7. 题目: Oxygen availability regulates the quality of soil dissolved organic matter by mediating microbial metabolism and iron oxidation
8. 题目: Peroxydisulfate activation using Fe, Co co-doped biochar and synergistic effects on tetracycline degradation
In this study, a low-cost and stable bimetallic biochar (Fe-Co/BC) was synthesized and used to activate peroxydisulfate (PDS) for tetracycline (TC) degradation. The optimized Fe-Co/BC-3 exhibited excellent catalytic activity with a kobs of 0.082 min-1, which was over 70, 25, 20 and 13 times those of PDS, pure BC, Fe/BC and Co/BC, respectively. The significantly enhanced catalytic performance can be attributed to the synergistic effects of iron and cobalt, where Co was inferred to be the dominant catalytic site for SO4•- generation, while Fe played a key role to the synergism with Co by acting as the primary adsorption site for the reaction substrates. The excellent anti-interferences of the Fe-Co/BC-3/PDS system in the environmental background further validated the superiority of the synergistic effects. This study is expected to improve the efficiency of the synthesis for bimetallic materials and elucidate the rational design for PDS activation.
9. 题目: Resource utilization of chicken manure to produce biochar for effective removal of levofloxacin hydrochloride through peroxymonosulfate activation: The synergetic function of graphitization and nitrogen functionality
Transforming hazardous livestock manure into biochar as an advanced oxidation processes catalyst is a two-in-one strategy to treat waste by waste. In this work, a self-modified biochar catalyst obtained from chicken manure is developed for peroxymonosulfate activation to degrade levofloxacin hydrochloride. The deterioration rate of levofloxacin hydrochloride reached 89% in 40 min, after three cycles of the catalyst, the LFX still maintained 52% degradation rate. And under low levofloxacin hydrochloride concentration, the degradation rate can reach 99% within 40 min. Apart from catalyst characterization and optimization, the effects of catalyst, peroxymonosulfate, levofloxacin hydrochloride, co-existing anions, and natural organic matter concentrations during the reaction are investigated. Additionally, the quenching experiments and electron spin resonance spectroscopy both reveal the reaction mechanism. As the graphitic nitrogen combined with the sp2-hybridized carbon in biochar was highly electronegative, thus appealing electrons from neighboring carbon networks, making the adjoining carbon atoms to be positively charged, which facilitated the degradation process. The oxidative degradation of levofloxacin hydrochloride was ascribed to non-radical routes including surface-bound radicals, h+ and 1O2 mediated oxidation, the contribution rates were 91%, 93.5%, and 96.8%, respectively. Moreover, possible degradation pathways of levofloxacin hydrochloride are studied by Density Functional Theory (DFT) and LC-MS analysis. This work provides a novel method to produce chicken manure biochar by self-modified chicken manure during biochar pyrolysis for peroxymonosulfate activation in organic contaminations abatement and reveals the combined effect of graphitization and nitrogen functionalization while providing new ideas for the resource utilization of chicken manure.
10. 题目: Decoupled cycling of carbon, nitrogen, and phosphorus in a grassland soil along a hillslope mediated by clay and soil moisture
Grasslands extend across a variety of topographies including non-flat hilly areas with varied soil texture and moisture that can mediate soil biogeochemical cycling of carbon (C), nitrogen (N) and phosphorus (P). In this study we examined soil organic C, total N and P pools (both inorganic and organic), as well as gross N mineralisation (GNM, as a measure of microbial activity and N dynamics) and microbial C, N and P in winter and spring along a grassland hillslope. Our results showed that variation in soil clay and associated soil moisture were the most important mediators affecting C and N dynamics along the grassland elevational gradient. Total organic C pools were highest where the clay content was highest, likely because of the sorption capacity of clay stabilising organic matter against microbial decomposition. Likewise, the variation in soil organic N pools along the hillslope was mostly controlled by clay and soil moisture effects on microbial stabilisation of organic N. Furthermore, microbial C, N and GNM increased with increased soil moisture, suggesting that microbial activity was limited by soil moisture. In contrast, soil P pools were not related to clay and soil moisture, while soil organic P was decoupled from soil organic C and N pools along the hillslope. Possibly, differences in microbial stabilisation and mineralisation pathways (oxidation for C and N, hydrolysis for P), microbial homeostatic regulation of C, N and P, and P fixation resulted in a decoupling of P from C and N cycling in this grassland. We conclude that variation in clay and associated soil moisture along grassland hillslopes can have important but non-unidirectional effects on soil C, N and P cycling.
11. 题目: Anthropogenic-driven chronological increase of sediment organic carbon burial in a river-lake system
Total organic carbon (TOC) in lake sediments from upstream catchments is deposited and buried in substrate, recording historical environmental changes. However, the linkage among natural variability, anthropogenic activity, and TOC burial for has not yet been clarified. This study examined the lake sediments of five 200-cm-deep dated depositional cores in west Dongting lake, China to quantify the magnitude, allocation, and amplitude of TOC burial. 44.47–59.36% of TOC burial flux was buried at 100–200 cm, suggesting lake sediments at deep layers stored considerable carbon. TOC burial rate (BRTOC) decreased along the lake entrance to its body, which was explained by the geochemical differences. Since 1900, BRTOC presented an increasing with a 4–7 times uptrend, showing three sedimentary stages with the increased human disturbance, such as deforestation, hydroelectric facilities. Moreover, the coefficient of variation of BRTOC in the third stage was lower than that in the second stage for the implementation of watershed reforestation and reservoir construction. Our findings stressed that natural variations of lake sedimentation background induced the change of TOC burial among the depositional sites, and that enhanced anthropogenic perturbation drove its chronological increases. This research unveiled the linkage between TOC burial, natural variability, and human disturbance from the perspective of burial evolutions in a lacustrine sedimentary environment.
12. 题目: Quantifying Seasonal Particulate Organic Carbon Concentrations and Export Potential in the Southwestern Ross Sea Using Autonomous Gliders
13. 题目: Performance study of fly-ash-derived coagulant in removing natural organic matter from drinking water: synthesis, characterization, and modelling
This study is an attempt to develop a liquid coagulant using fly ash (FAC) for removing natural organic matter (NOM) from drinking water systems. Acid–alkali leaching and polymerization technique was used for developing FAC. Characterization of FAC was performed using Fourier-transform infrared spectroscopy (FESEM), field emission scanning electron microscopy (FTIR), and X-ray diffraction (XRD) to assess the surface morphology and functional groups present. FE SEM analysis revealed uneven, coarse, and irregular structure with numerous pores, an indicative of their high adsorption capacity. XRD study revealed that Al, Fe, and Si are the major constituent group of FAC. FAC demonstrated excellent potential in removing THMs precursors: dissolved organic carbon (84.46%), UV254 (90.57%), and turbidity (96.85%) from the drinking water systems. Charge neutralization followed by adsorption is the main mechanism behind NOM removal. Moreover, FAC also showed good capability in minimizing the reactivity of NOM (ASI—72.86%) towards THM formation. FAC proved to be a good alternative for conventional coagulant used in drinking water treatment and can be effectively used for reducing NOM content of raw water which leads to the formation of THMs on chlorination.
14. 题目: Removal of Tetracycline from aqueous solution using composite adsorbent of ZnAl layered double hydroxide and bagasse biochar
A new composite adsorbent of biochar derived from bagasse and ZnAl-layered double hydroxide was produced by the in-situ growth method. The prepared biochars were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) analysis, the Brunauer-Emmett-Teller (BET) isotherms, Scanning electron microscopy (SEM), Energy Disperse X-ray (EDX) spectroscopic and Mular-Roberts titration analyses. The best Zn:Al molar ratio for the ZnAl-LDH/BGC composite to adsorb tetracycline was 3:1. The specific surface area of ZnAl-LDH/BGC31 was 456.39 m2/g compared to 404.05 m2/g for BGC. The optimal pH, contact time and initial TC concentration for TC adsorption were 6.0, 120 min and 25 mg/L, respectively. The ZnAl-LDH/BGC31 had a maximum adsorption capacity (q) of 41.98 mg/g. The obtained data were analyzed with Langmuir, Freundlich and Tempkin isotherm models. Kinetic data were evaluated by using pseudo-first and pseudo-second-order kinetic models. The adsorption mechanism of ZnAl-LDH/BGC31 to remove TC was likely based on the pore-filling process, electrostatic attraction and conjugate effect. ZnAl-LDH/BGC31 had significant adsorption capacity after five reusabilities.
15. 题目: Effects of decadal nitrogen addition on carbon and nitrogen stocks in different organic matter fractions of typical steppe soils
Recent frameworks have proposed that division of soil organic matter (SOM) into particulate and mineral-associated organic matter (POM and MAOM) can help us better understand SOM cycling and its responses to increasing atmospheric nitrogen (N) deposition. However, responses of these factions to N deposition with combination of their relative distribution across soil profile remain unclear. Here we determined total N and soil organic carbon (SOC) as POM and MAOM separately in soils at depths of 0–10, 30–40 and 70–100 cm after 10-year N addition (at rates of 50, 10, 2 and 0 g m−2 yr−1) in a typical steppe. We further calculated their stocks in POM, MAOM and bulk soil and detected their relationships with both physicochemical features and microbial properties. Nitrogen addition increased the stocks of SOC (POM: +23 %; MAOM: +11 %) and total N (POM: +27 %; MAOM: +10 %) in both POM and MAOM fractions in topsoil (0–10 cm), but increased only in MAOM in 30–40 cm (SOC: +24 %; total N: +24 %) and 70–100 cm (SOC: +15 %; total N: +13 %) soils. Moreover, the increasing effects were strengthened with increasing N addition rates. We found that the share of SOC and total N in the MAOM was slightly decreased by N addition in topsoil, but significantly increased in deeper soils. Soil physicochemical features exerted stronger controls than microbial properties in the distribution of SOC and total N in the two fractions regardless of soil depth. SOC and total N contents of MAOM were correlated negatively with soil pH across the soil profile, and were correlated positively with bulk soil total N, dissolved organic N and inorganic N. Our findings imply that more soil C would be stabilized as MAOM under increasing atmospheric N deposition, and therefore the C saturation level of MAOM should be a target for further studies and be considered in predicting SOM dynamics, especially in N-limited grassland ecosystems.
16. 题目: Exploring the impact of biochar supplement on the dynamics of antibiotic resistant fungi during pig manure composting
The purpose of this study was to investigate antibiotic resistant fungal (ARF) communities in pig manure (PM) composting employing two different biochar (coconut shell-CSB and bamboo biochar-BB) as amendment. Three treatments (Control, 10% CSB and 10% BB) were designed and indicated with T1 to T3. Experimental results declared that the fungal abundance significantly reduced among the both biochar applied treatments but three dominant phyla Ascomycota, Basidiomycota and Mucoromycota were still relatively greater abundance present. There were significant differences (p < 0.05) in the relative abundance and diversity of fungi among all three treatments. Interestingly, biochar addition regulated the overall fungal community in final compost. Compared with the control group, the abundance of fungi was positively mobilized, and especially CSB showed a better effect. Conclusively, biochar has potential to inhibit and reduce the ARGs population and mobility in compost. Thus, these findings offer new insight to understand the succession of ARFs during PM composting.
17. 题目: Biogeochemical dynamics of particulate organic phosphorus and its potential environmental implication in a typical “algae-type” eutrophic lake
Organic phosphorus (Po) plays a very important role in the process of lake eutrophication, but there is still a lack of knowledge about the internal cycle of Po in suspended particulate matter (SPM) dominated by algal debris. In this study, the characterization of bioavailable Po by sequential extraction and enzymatic hydrolysis showed that 45% of extracted TP was Po in SPM of Lake Dianchi, and 43–98% of total Po in H2O, NaHCO3 and NaOH fractions was enzymatically hydrolyzable Po (EHP, H2O−EHP: 31–53%). Importantly, labile monoester P was the main organic form (68%) of EHP, and its potential bioavailability was higher than that of diester P and phytate-like P. According to the estimation of P pools in SPM of the whole lake, the total load of Pi plus EHP in the H2O extract of SPM was 74.9 t and had great potential risk to enhance eutrophication in the lake water environment. Accordingly, reducing the amount of SPM in the water during the algal blooming period is likely to be a necessary measure that can successfully interfere with or block the continuous stress of unhealthy levels of P on the aquatic ecosystem.
18. 题目: Dissolved organic matter concentration and composition discontinuity at the peat–pool interface in a boreal peatland
19. 题目: Effects of biochar on the degradation of organophosphate esters in sewage sludge aerobic composting
In this study, the impact of biochar on the degradation of organophosphate esters (OPEs) during the aerobic composting of sewage sludge was investigated. Three treatments were conducted with different percentages of biochar in the compost, including 5%, 10%, and 20%. The treatment with 10% of biochar showed the longest thermophilic phase compared to that of 5% and 20% of biochar, which greatly promoted the decomposition of organic matter. In addition, the degradation rate of the hard-to-degrade chlorinated-OPEs was significantly increased by 10% biochar, reaching to 57.2%. Correspondingly, approximately 43.6% of the total concentration of OPEs (Σ6OPEs) was eliminated in the presence of 10% of biochar, which was higher than the treatments with 5% and 20% of biochar. Biochar significantly influenced the microbial community structure of compost, but the previously reported organophosphorus-degrading bacteria did not play a major role in the degradation of OPEs. The redox ability of the increased oxygen-containing functional groups such as quinone on the surface of biochar and the biochar-mediated electron transfer ability may play an essential role in the degradation of OPEs during the composting process.
20. 题目: Trace metal complexation with dissolved organic matter stresses microbial metabolisms and triggers community shifts: The intercorrelations
The response of microorganisms to heavy metal-dissolved organic matter (Me-DOM) complexation is critical for the microbial-mediated coupled biogeochemical cycling of metals and DOM. This study investigated the impact of typical metals [As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn (at an environmentally-relevant concentration of 200 ppb)], model DOM substrates [humic acids (HA) and bovine serum albumin (BSA)], and their complexation on riverine microbial DOM metabolisms. DOM biodegradability decreased after the metal complexation (especially Co, Cr, and Mn for HA and Ni for BSA). While microbial transformation of humics and proteins was observed, components with lower aromaticity and hydrophobicity were accumulated during the cultivation. The substrate difference and metal speciation changed community compositions and resulted in distinctive community member networks, which accounted for the varied metabolic DOM patterns. The correlations indicated that rather than metal uptakes, Me-DOM complexation and community shifts controlled microbial DOM metabolisms. Microbial BSA metabolisms were less correlated to the key genera identified by network analysis or community diversity. Instead, they were sensitive to metal speciation, which may be attributed to the complicated utilization and production of proteins and their essential roles in detoxification. The constructed correlations among metals (Me-DOM complexes), DOM metabolisms, and community shifts provide strong implications for the biogeochemical function of Me-DOM complexes and highlight the effect of metal speciation on microbial protein metabolisms even at trace concentrations.