12561. 题目: Soil organic carbon stock and its changes in a typical karst area from 1983 to 2015
12562. 题目: Redox-Active Biochar and Conductive Graphite Stimulate Methanogenic Metabolism in Anaerobic Digestion of Waste-Activated Sludge: Beyond Direct Interspecies Electron Transfer
12563. 题目: Soil carbon loss by experimental warming in a tropical forest
12564. 题目: Soil organic matter, nitrogen and pH driven change in bacterial community following forest conversion
Fast expansion of forest conversion to monoculture plantations has profound effects on ecosystem structure and functions. Through altering litter and rhizodeposition composition as well as one-sided effects on soil chemical properties, monoculture plantations may tremendously decrease biodiversity and functions of soil microorganisms. We investigated the impacts of conversion of natural evergreen and deciduous broad-leaf forest (Forest) to four 5-year old monoculture plantations (plantations), such as Camellia oleiferaAbel.(Oil), Amygdalus persica (Peach), Myrica rubra (Lour.) S. et Zucc.(Berry) and Cunninghamia lanceolata (Lamb.) Hook.(Fir), on soil properties and bacterial community and its driving factors using the high-throughput sequencing technique. Soil organic carbon, and total nitrogen decreased up to 59%–83% and pH increased by 0.31 units following the forest conversion. The changes in soil properties and bacterial communities were depended on the type of the plantation. Bacterial diversity increased by 6.5% after forest conversion. The relative abundances of Acidobacteria, Proteobacteria, Bacteroidetes and Actinobacteria in the Forest were remarkably higher compared with all plantations, whereas that of Chloroflexi and Planctomycetes was less. All plantations had low abundance of Acidobacteria, while the highest abundance of Proteobacteria, Actinobacteria and Planctomycetes was observed under Peach. The co-occurrence patterns of bacterial communities identified rare taxa rather than abundant taxa as central players in bacterial network. The redundancy analysis indicated that the variation in the composition of bacterial community was mainly driven by soil pH, organic carbon and total nitrogen content. Therefore, good management practices, such as reasonable fertilization and soil erosion prevention, need to be developed for monoculture plantations to mitigate the depletion of nutrients and to enhance microbial functioning after forest conversion.
12565. 题目: Co-application of a biochar and an electric potential accelerates soil nitrate removal while decreasing N2O emission
Denitrification is an important mechanism for mitigating groundwater nitrate (NO3−) pollution. Our previous results showed that electric potential application (−0.5 V versus standard hydrogen electrode) accelerated subsoil NO3− reduction efficiently, but nitrous oxide (N2O) emissions were also elevated with the application of the electric potential. Biochar has previously been considered to act as an electron shuttle to mitigate soil N2O emission. Therefore, this study aimed to investigate if, and how, a combined amendment of electric potential and biochar could simultaneously accelerate soil NO3− reduction and suppress N2O emission. The results showed that the electric potential application alone (E) significantly increased the soil N2O emission by 144% compared with soil only (CK), whereas the co-application of electric potential and biochar (E + BC) markedly decreased the soil N2O emission by 83%, which was more than two times higher than the efficiency of biochar amendment alone (BC) on soil N2O mitigation (35%). Moreover, the E + BC treatment further decreased the N2O/(N2O + N2) emission ratio by 62% on average at the end of the experiment compared with the BC treatment. These results indicate that there is an interaction between biochar and electric potential on soil N2O mitigation. Contrary to the E + BC treatment, the combined amendment of electric potential and H2O2-oxidized biochar (E + BC_H2O2) increased the soil N2O emission by 151% compared with the BC treatment. The cathode coulombic efficiency did not differ significantly between the E + BC_H2O2 and E treatments, but the cathode coulombic efficiency in the E + BC treatment was almost double that of the E treatment. Besides, the abundance of Proteobacteria, which include most electrotrophic microorganisms, and the nosZ/(nirS + nirK) gene ratio were higher in the E + BC treatment than that in other treatments. These results indicate that the biochar interacts with electric potential treatment via shuttling electrons from electrodes to soil electrotrophic denitrifying consortia and consequently accelerates soil NO3− reduction and decreases the N2O/(N2O + N2) emission ratio.
12566. 题目: Influence of hydro-morphologic variables of forested catchments on the increase in DOC concentration in 36 temperate lakes of eastern Canada
In the last decades, a worldwide increase in dissolved organic carbon (DOC) concentrations has been observed in temperate and boreal lakes. This phenomenon has several detrimental effects on the aquatic life and affect local C geochemical cycles. In this study, we measured DOC concentration in the water column of 36 lakes located in eastern Canada over a period of 35 years (1983–2017) and assessed the influence of climatic, hydrologic and morphometric variables on both DOC concentrations and on the rate of DOC changes (∆DOC). Our data show that morphometric and hydrologic variables have a stronger direct influence on lake water DOC concentrations than vegetation and climatic variables. DOC concentration strongly increased with the drainage ratio and the surface covered by organic deposits, which together explained 59% of the variance. As expected, we observed a significant increase in lake water DOC concentration in 72% of the surveyed lakes, which averaged 20% over the study period. Meanwhile, lake water SO42− concentration decreased by 60%. ∆DOC was poorly influenced by the rate of changes in lake water SO42− as well as by the rate of changes in mean annual air temperature and precipitation. ∆DOC was more related to the vegetation type and the morphometry of the catchment: a model including the percentage of conifers, terrestrial catchment area and ∆Cl yielded a variance explanation of 39%. This shows that the rate of increase was primarily driven by morphometric variables which did not change over the study period.
12567. 题目: Exogenous extracellular polymeric substances as protective agents for the preservation of anammox granules
The preservation of anammox granules is of great significance for the rapid start-up of the anammox process and improvement of performance stability. Therefore, it is necessary to explore an economical and stable preservation strategy. Exogenous extracellular polymeric substances (EPS) were used as protective agents for the preservation of anammox granules in this study. In brief, EPS from anammox sludge (A-EPS) and denitrifying sludge (D-EPS) were added to preserve anammox sludge at 4 °C and room temperature (15–20 °C). The results showed that A-EPS addition at 4 °C was the optimal condition for the preservation of anammox granules. After 90 days of preservation, the specific anammox activity (SAA) of the anammox granules remained at 92.7 ± 2.2 mg N g−1 VSS day−1 (remaining ratio of 33.4%), while that of the sludge with D-EPS addition at the same temperature was only 77.1 ± 3.2 mg N g−1 VSS day−1 (remaining ratio of 27.8%). The nitrogen removal efficiency of the experimental group with D-EPS at room temperature was 85.9%, and that of the A-EPS group reached 90.6% under the same temperature conditions. The abundance of the functional genes hzsA, hdh and nirS of the sludge (4 °C; A-EPS addition) after recovery were 138.5%, 317.1%, and 375.9%, respectively, of those of sludge from the D-EPS-added group at the same temperature. RDA revealed the contribution of proteins to the preservation process. Overall, this study provides an economical and robust strategy for the preservation of anammox granules.
12568. 题目: Effects of nitrogen deposition and increased precipitation on soil phosphorus dynamics in a temperate forest
Nitrogen (N) deposition has increased dramatically since the industrial revolution due to anthropogenic activities. Meanwhile, global mean precipitation was predicted to rise. Although these two global change factors are co-occurring naturally, rare studies were contributed to understand how N deposition and increased precipitation interactively affect soil phosphorus (P) dynamics. In the present study, we conducted a novel canopy N and water addition experiment to investigate the effects of N deposition, increased precipitation, and their interactions on soil P dynamics in a temperate forest. We found that soil primary mineral P was significantly reduced after six years of canopy N deposition mainly due to N-induced soil acidification. Along with the reduction of primary mineral P, soil secondary mineral P was increased with N deposition due to increased exchangeable Al and Fe. Soil organic P associated with Al and Fe, microbial biomass P and phosphatase activity were also increased by N deposition. Our results also revealed that soil primary mineral P was reduced, and secondary mineral P was increased by increased precipitation. Increasing precipitation also significantly prompted soil microbial biomass P, which could explain the increase of soil secondary mineral organic P. In addition, we also found there were interactive effects between N deposition and precipitation on soil primary mineral P and secondary mineral organic P. The effect of N on these properties was strengthened by precipitation increase. Collectively, our results suggest that N deposition and increased precipitation can shift the composition of soil P fractions and drive the depletion of the primary mineral P. Thus, these two global change factors could synergistically affect soil P dynamics.
12569. 题目: Removal of tetracycline with aluminum boride carbide and boehmite particles decorated biochar derived from algae
For the first time, using aluminum-boron electrodes in the electrocoagulation cell for harvesting the cultivated Chlorella microalgae and then performing a hydrothermal process of producing biofuel, mesoporous biochar was produced with an average pore diameter of 11.62 nm, a high specific surface area of 126.4 m2/g and a total pore volume of 0.55 cm3/g. Based on the chemical characterization, aluminum boride carbide (Al3B48C2) and boehmite [Al2(OOH)2] were identified in the biochar composition so that 7.17 wt% Al and 16.67 wt% B were measured on the biochar surface by EDS analysis. As the by-product of hydrothermal converting microalgae Chlorella into biofuel, the residual biochar was innovatively used to separate tetracycline from aqueous solutions. The nonlinear form of the Freundlich model fitted the adsorption equilibrium data well with the least error function value explained by the intraparticle diffusion model. The maximum adsorption capacity of 25.94 mg/g was obtained through endothermic physical adsorption.
12570. 题目: Impact of hydrochar and biochar amendments on sorption and biodegradation of organophosphorus pesticides during transport through Danube alluvial sediment
This work investigates the transport behaviour of selected organophosphorus pesticides, OPPs (chlorpyrifos, CP; chlorpyrifos-methyl, CPM; chlorfenvinphos, CF) through Danube alluvial sediment in the presence of hydrochars and biochars. The investigated hydrochar, obtained at three different temperatures (180 °C, 200 °Cand 220 °C), originated from sugar beet shreds (SBS) and Miscanthus×giganteus (MIS). Results are described by conventional advective-dispersive equation (ADE). Retardation coefficients (Rd) for all OPPs were in the range 6.2–16. Biodegradation was 4.15 and 1.80 for CPM and CP, respectively, while for CF biodegradation did not occur. The addition of carbon rich materials increases retardation of all OPPs in the range from 4 to 18 times depending on the material. Column experiment results indicated that biodegradation of OPPs occurred (up to λ = 13). In order to confirm that biodegradation occurred in the column experiments, we isolated OPPs degrading microorganisms for the first time from the alluvial sediment. A strain capable of degrading CP and CPM was isolated and identified as Bacillus megaterium BD5 based on biochemical properties, MALDI TOF and 16S rRNA analysis (99.54% identity). The results demonstrate that hydrochars, biochars and isolated degrading bacteria may be effective agents for reducing the mobility of or removing OPPs in contaminated soils or sediments.
12571. 题目: Oxidative transformation of 1-naphthylamine in water mediated by different environmental black carbons
Black carbons (BCs) are ubiquitous in the natural environment and can significantly influence the environmental behavior of pollutants. This work examined the mediating effects of graphite, soot, and biochar on 1-naphthylamine (1-NA) oxidation under aerobic conditions. It was shown that the three BCs significantly promoted the oxidation of 1-NA in the dark, and the mediation efficiency of graphite was much greater than that of soot or biochar. The oxidation products were the coupling oligomers (dimers and trimers) and the oxygen-containing oligomers of 1-NA (di-OH-1-NA, OH-azo naphthalene, OH-trimers and amino-naphthoquinone derivatives etc.). The phenolic OH on BCs were identified as the active sites for 1-NA oxidation, which could stimulate O2 to produce reactive oxygen species through successive single electron transfer and then cause 1-NA oxidation. Moreover, the superior catalytic performance of graphite was also related to its high electrical conductivity. The synergies between the sp2-hybridized carbon surface and the active sites (such as phenolic OH and defects) facilitated the oxidation of 1-NA on graphite. Findings in this study not only are helpful for better understanding the reactivity of environmental BCs, but also provide new insights into the risk assessment of 1-NA in the natural environment.
12572. 题目: Ultra-high synergetic intensity for humic acid removal by coupling bubble discharge with activated carbon
Humic acid (HA) removal research focuses on the global water treatment industry. In this work, efficient HA degradation with an ultra-high synergetic intensity is achieved by combined bubble discharge with activated carbon (AC). Adding AC to the discharge greatly improves HA removal efficiency and degradation speed; the synergetic intensity reaches 651.52% in the combined system, and the adsorption residual on AC is 4.52%. After 90 min of treatment, the HA removal efficiency reaches 98.90%, 31.29%, and 7.61% in the plasma-AC combined, solo bubble discharge, and solo AC adsorption systems, respectively. During the plasma process, the number of pore structures and active sites and the amount of oxygen-containing functional groups on the AC surface increase, resulting in a higher adsorption capacity to reactive species (H2O2 and O3) and HA and promoting interactions on the AC surface. For HA mineralization, the presence of AC greatly promotes the destruction of aromatic structures and chromophoric HA functional groups.
12573. 题目: Reduced nitrification by biochar and/or nitrification inhibitor is closely linked with the abundance of comammox Nitrospira in a highly acidic sugarcane soil
12574. 题目: Effectiveness, stabilization, and potential feasible analysis of a biochar material on simultaneous remediation and quality improvement of vanadium contaminated soil
Biochar additions to soil have been proposed as an environment-friendly way to enhance the soil nutrients or to amend the contaminated soils; however, few studies have evaluated the effectiveness of biochars from an integrated perspective of soil remediation and quality improvement, especially for the soil contaminated by vanadium with increasing prevalence, complex species and chemistry, widespread toxicity to organisms. Herein, this gap is addressed by using a biochar to evaluate the effectiveness of both remediation and quality improvement of a vanadium contaminated soil. Based on the physicochemical and morphology properties, the optimal biochar with a good porous structure and abundant surface functional groups prepared by pyrolyzing rice straw at 650 °C and sieving through a 200 mesh (RS-T650-P0.075) was selected from 18 candidates. The increase of pH (1.72), organic matter content (3.80%), and available P content (9.17 mg kg−1) of soil and the decrease of bioavailable vanadium (225.59 ± 16.25 mg vanadium kg−1 soil) in soil during a 10-week experiment indicated an effective and stable improvement of soil quality and treatment for soil vanadium pollution, by high RS-T650-P0.075 application (3%) to soil contaminated at high exogenous vanadium level (1000 mg vanadium kg−1 soil). Analysis of the cost-benefit and environmental influence confirmed the potential feasibility for practical applicating the RS-T650-P0.075 to treat the vanadium contaminated soils. Overall, the RS-T650-P0.075 can be served as a cost-effective and ecofriendly amendment for both soil quality improvement and the vanadium contaminated soil remediation.
12575. 题目: Investigation of the short-term effects of extracellular polymeric substance accumulation with different backwashing strategies in an anaerobic self-forming dynamic membrane bioreactor
The optimum operation strategy for a side-stream external anaerobic self-forming dynamic membrane bioreactor (AnSFDMBR) was investigated by coupling such a system with an up-flow anaerobic sludge blanket reactor. Time-based backwashing with different intervals and transmembrane pressure (TMP)-based backwashing were compared as the operation strategies of the AnSFDMBR. The system performance, extracellular polymeric substance (EPS) accumulation in the dynamic layer and on the membrane mesh of the AnSFDMBR, and the physical properties of the dynamic layer were closely monitored. Both operation strategies achieved stable operation with effluent turbidity less than 5 nephelometric turbidity units with a slowly increasing TMP. However, with the time-based backwashing strategy, the EPS accumulation rate in the dynamic layer was more than 20 times higher than that on the mesh, indicating that frequent backwashing might have a negative impact on the AnSFDMBR. The impacts of EPS accumulation on the membrane mesh were negligible considering the small amount of EPS residual and the large pore size of the mesh. On the contrary, the EPS accumulation in the dynamic layer changed the layer's physical properties and further impacted on the performance of the AnSFDMBR. The accumulation of polysaccharides in the dynamic layer was the main reason for the layer's compactness, which was negatively correlated with the specific surface area and further led to the TMP increase. The polysaccharides in the dynamic layer-to-sludge ratio increased to around 1.6 with only 5 days of time-base operation. With TMP-based operation, it took more than 10 days for polysaccharides in the dynamic layer-to-sludge ratio reaching 1.6. The low TMP increase rate, high effluent quality, and slow EPS accumulation with TMP-based backwashing indicated TMP-based operation is applicable in the studied AnSFDMBR. Nevertheless, the correlation between TMP and the accumulation of polysaccharides should be further investigated to find the optimum TMP for backwashing.
12576. 题目: Elevated temperature enhances the bioavailability of pyrene to Daphnia magna in the presence of dissolved organic matter: Implications for the effect of climate warming
Dissolved organic matter (DOM) is an essential factor in natural waters to affect the bioavailability of hydrophobic organic compounds (HOCs). Climate warming may influence the partition of HOCs between DOM and water as well as the physiology of organisms. Thus, we hypothesized that elevated temperature might affect the bioavailability of HOCs in the presence of DOM. To test this hypothesis, the effect of temperature on the bioavailability of pyrene to Daphnia magna (D. magna) in water-DOM (fulvic acid) system was investigated. The results showed that, although the concentration of freely dissolved pyrene increased slightly with temperature in the presence of DOM when the level of total dissolved pyrene was kept constant, D. magna immobilization (increased by 50.0–167%) and internal body burden of pyrene (increased by 18.4–41.5%) increased significantly with every 4 °C increase in temperature (16, 20, 24 °C). The main reasonable explanation for this result is that elevated temperature promoted pyrene uptake by D. magna. It was found that the increase percentage of 1-hydroxypyrene (main metabolite of pyrene) concentrations with temperature was higher than that of pyrene concentrations in the body except gut of D. magna. This result indicated that increased temperature might enhance the metabolic rates of D. magna, thus leading to increased uptake rate of freely dissolved and DOM-associated pyrene. This study suggests that elevated temperature might enhance the bioavailability of HOCs in natural waters through influencing both the bioavailable fraction of HOCs and their uptake rates in aquatic organisms, and this should be considered for evaluating their eco-environmental risks under the context of climate warming.
12577. 题目: Soil carbon storage and carbon sources under different Spartina alterniflora invasion periods in a salt marsh ecosystem
12578. 题目: Discovery of large molecules as new biomarkers in wastewater using environmental proteomics and suitable polymer probes
The capability of monitoring large molecules as possible biomarkers in wastewater will be an important contribution to the new field of sewage epidemiology. Here, we explore the use of polymer probes together with untargeted proteomics for large scale protein analysis in sewage and treated water. Polymeric probes were immersed in the influent, anoxic reactor and effluent waters of a Spanish WWTP during 11 days. Proteins sorbed were extracted and identified by mass spectrometry. A total of 690 proteins from bacteria, plants and animals, including human, were identified showing different proteome profiles in the different sites. Bacterial proteins (510) pointed at 175 genera distributed in 22 bacterial classes. The most abundant were EF-Tu, GroEL and ATP synthase which were contributed by a high number of species. Human was the species contributing the greatest number of identified proteins (57), some in high abundance like keratins. Human proteins dominated in the influent water and were efficiently removed at the effluent. Several of the proteins identified (S100A8, uromodulin, defensins) are known disease biomarkers. This study provides the first insight into the proteome profiles present in real wastewater.
12579. 题目: The characteristics of pharmaceutical sludge-derived biochar and its application for the adsorption of tetracycline
In this study, the specific surface area, pore structure, surface functional groups and microstructure of the biochar derived from the pyrolysis of pharmaceutical sludge are analyzed. The results showed that the pyrolysis temperature had a great influence on the properties of sludge-based biochar (SBB), and the specific surface area of the SBB first increased and then decreased with an increase in the pyrolysis temperature. The maximum specific surface area was 214.97 m2/g at 600 °C, while the pore volume increased with an increase in the pyrolysis temperature. The pickling process removed impurities in the SBB and increased the specific surface area of the material (319.80 m2/g). The effects of pyrolysis temperature, pH, adsorption time, and initial pollutant concentration on the adsorption process were also studied. The results showed that the adsorbents had good pH adaptability, and biochar produced at 600 °C had the best adsorption capacity (94.69 mg/g). Pickling increased the adsorption capacity to 157.38 mg/g. The results showed that pharmaceutical sludge has great potential as a raw material for the preparation of adsorbent. These benefits can compensate for the cost of sludge pyrolysis treatment.
12580. 题目: Goethite dispersed corn straw-derived biochar for phosphate recovery from synthetic urine and its potential as a slow-release fertilizer
In this study, goethiete (α-FeOOH) -biochar (BC) composites were successfully developed from a co-precipitation reaction under alkaline conditions (pH = 11.93) and used as the adsorbent for phosphate recovery from urine. The morphology and crystallinity of α-FeOOH-BC composites were characterized by scanning electron microscopy and X-ray diffraction. α-FeOOH loaded BC was found to be amorphous. This may be caused by the Si residue in BC. The Elovich model and the Langmuir model fit better to the kinetic and isotherm results of α-FeOOH-600BC, respectively, indicating that phosphate adsorption is mainly a chemisorption and monolayer adsorption process. The α-FeOOH-600BC with amorphous structure showed higher adsorption capacity than crystalline α-FeOOH, and the maximum phosphate sorption capacity reached 57.39 mg g−1. Additionally, the extractable phosphate of this material was approximately 967.5 mg P·kg−1 suggesting the α-FeOOH-600BC after adsorption could be a promising alternative as a slow-phosphate-release fertilizer. Fourier-transform infrared and X-ray induced photoelectron spectroscopy results showed that the active sites of the adsorption of phosphate were the Fe-OH bonds that formed inner-sphere complexes (Fe-O-P).