101. 题目: Seasonality of DOC export from a Russian subarctic catchment underlain by discontinuous permafrost, highlighted by high‐frequency monitoring
期刊: Journal of Geophysical Research: Biogeosciences
作者: L. Gandois, N Tananaev, A. Prokushkin, I. Solnyshkin, R. Teisserenc
摘要: Intense climate change and permafrost degradation impact northern watersheds and ultimately organic carbon transfer from terrestrial to aquatic ecosystems. We investigated the contemporary dissolved organic carbon (DOC) dynamics in a northern catchment underlain by discontinuous permafrost (Graviyka River, northern Siberia), where historical meteorological and hydrological data are available since 1936. Mean annual air temperature (MAAT), in contrast to precipitation and discharge was found to show a significant increasing trend since 1950. Using in situ sensing of fluorescent dissolved organic matter (fDOM), we estimated DOC concentrations at a high temporal frequency (1h) during three years (2015-2018), and calculated annual specific fluxes of 5.2 to 5.5 g C m2 yr-1. High DOC concentrations (above 10 mg L-1) are sustained all year, exhibiting nearly chemostatic behavior. Nevertheless, the high-frequency survey of DOC and other water parameters revealed the seasonality of DOC origin and pathways in the watershed. The spring freshet dominates the annual export (up to 80%), but summer and autumn floods can also contribute up to 9 and 8% respectively. The high-frequency sampling was able to capture the specific dynamic of DOC concentration during spring flood (DOC peak preceding discharge, dilution during the spring freshet) and summer and autumn floods (contribution of DOC-rich, low conductivity water). These observations suggest a significant contribution of organic-rich water originating in peatlands, potentially from degrading palsas. The study demonstrates both that high-frequency sampling is essential to capture key events for DOC export, and that more long-term monitoring is urgently needed in these rapidly evolving watersheds.
102. 题目: Immobilization and redistribution process of As(V) during As(V)-bearing ferrihydrite reduction by Geobacter sulfurreducens under the influence of TiO2 nanoparticles
期刊: Journal of Hazardous Materials
作者: Xiaofeng Yi, Shenhua Huang, Lu Chang, Zhaoshou Wang, Yuanpeng Wang
摘要: The redistribution process of arsenate (As(V)) and the variation in As(V) content in different locations must be clarified to ensure low mobility of As(V) during microbial ferrihydrite reduction. In this study, we investigated As(V) immobilization and redistribution processes when ferrihydrite was incubated with Geobacter sulfurreducens in the presence of titanium dioxide (TiO2) nanoparticles. Our study results showed that, As(V) in the aqueous phase and ferrihydrite were redistributed on light minerals (goethite), heavy minerals (ferrihydrite and magnetite), and extracellular polymeric substances (EPS) induced by G. sulfurreducens during ferrihydrite reduction. Interestingly, we found that As(V) in the form of arsenate ion (AsO43-) was adsorbed by the functional groups of the EPS, while the formed FeII3(AsVO4)2 was wrapped in the network structure of EPS. Moreover, the addition of TiO2 nanoparticles did not promote but delayed the entire ferrihydrite reduction, As(V) immobilization and redistribution processes. Furthermore, changes in the aqueous arsenic and iron concentrations are closely related to the formation time of secondary minerals. Our study findings provide new insights into the As(V) immobilization process mediated by G. sulfurreducens under anaerobic conditions.
103. 题目: An exploration of manure derived N in soils using 15N after the application of biochar, straw and a mix of both
期刊: Science of The Total Environment
作者: Shuai Ding, Caibin Li, Xinyu Ding, Guitong Li, Guojun Ban, Zhongwen Xia, Xiaorong Zhao, Qimei Lin, Xiang Wang
摘要: It is common practice to apply manure onto soil as an effective way to increase soil fertility. However, the impact of different carbon sources on the transformation and fate of manure derived nitrogen (N) remains poorly understood. This study investigated the mineralization and immobilization turnover (MIT) of various manure-N fractions using sequential extractions and 15N tracing techniques combined after soil amendment with biochar, straw and mixtures thereof. Soil N was fractionated into mineral nitrogen (NH4+ and NO3−), microbial biomass nitrogen (MBN), hot water extractable organic nitrogen (HWDON), hydrochloric acid extractable organic nitrogen (HCl–N), and residual nitrogen (RN). Results showed that biochar addition increased the 15NH4+ content by 45% during the early stage. However, the high pH and labile C absence of biochar inhibited the remineralization of microbial immobilization N during the mid–to–late stage. Straw addition enhanced 15NH4+ assimilation by 10% to form HCl–15N. After that, microbial cellular structures and secondary metabolites were remineralized to meet crop N requirements. Adding carbon source mixtures with the organic fertilizer manifested the relationship between biochar and straw. The labile C content of the carbon sources rather than the C/N ratio was the critical factor regulating the N-MIT process. Overall, these findings offer new insights into the N transformation approaches using the co-application technique of organic amendments.
104. 题目: Unraveling the molecular mechanisms of Cd sorption onto MnOx-loaded biochar produced from the Mn-hyperaccumulator Phytolacca americana
期刊: Journal of Hazardous Materials
作者: Ping Wu, Peixin Cui, Ying Zhang, Marcelo Eduardo Alves, Cun Liu, Dongmei Zhou, Yujun Wang
摘要: Engineered biochar represents a promising material for green remediation practices. In this paper, we present an innovative approach to produce MnOx-loaded biochars by pyrolyzing the biomass of a Mn-hyperaccumulator species (Phytolacca americana). Batch sorption and stirred-flow kinetic experiments were combined with spectroscopic techniques to elucidate the mechanisms behind the Cd sorption onto those biochars, named here as PABCs. The incorporation of MnOx into the PABCs increased their surface densities of oxygen-containing functional groups. The average Mn leaching (< 9%) from PABCs was lower than that measured for the non-pyrolyzed biomass of P. americana (30-43%). PABCs pyrolyzed at 500 °C had Cd sorption capacities as high as 212-337mg/g, which achieved by far the best performance reported for biochar materials. The stirred-flow experiments showed that MnOx loading was instrumental in increasing both the Cd sorption onto PABCs as well as its irreversibility. Extended X-ray absorption fine structure spectroscopy revealed that the Cd immobilization occurred mainly through its association with organic matter (Cd-OM) and, to a lesser extent, with carbonate (CdCO3) and MnOx (Cd-MnOx). In short, MnOx-loaded biochar prepared from the biomass of a Mn-hyperaccumulator species proved to be an effective, sustainable, and eco-friendly material for remediating Cd-contaminated waters.
105. 题目: Removal of chlortetracycline from water by Bacillus cereus immobilized on Chinese medicine residues biochar
期刊: Environmental Technology & Innovation
作者: Sinan Zhang, Jihong Wang
摘要: Biochar-immobilized microorganism technology is an effective way to remove antibiotic contamination from water bodies. In this study, three common Chinese medicine residues (forsythia, erding and honeysuckle) were selected as raw materials for pyrolysis at different temperatures. The biochar obtained was used as a carrier to immobilize the highly efficient chlortetracycline-degrading bacterium Bacillus cereus LZ01 and analyze the complex’s removal characteristics and removal mechanism chlortetracycline. The results showed that the Chinese medicine residue biochar pyrolyzed at 500 °C had a higher removal capacity for chlortetracycline and could adsorb more microorganisms. The erding medicine residue biochar (EBC-500) pyrolyzed at 500 °C possessed a more developed pore structure and suitable nutrients. And the alkalinity of EBC-500 had the effect of relieving the inhibition of bacteria by acid, providing more suitable living conditions for the growth of bacteria, and improving the removal of chlortetracycline. Orthogonal experiments determined the optimal conditions for microbial immobilization by biochar: 10% microbial inoculum, 0.5 g biochar dosage, 0.097 - 0.15 mm biochar particle size, and 36 h immobilization time. The FT-IR spectra showed that the complex integrated all functional groups of biochar and degrading bacteria. The comparison of the removal effect before and after inactivation revealed that the removal mechanism of chlortetracycline in water by the complex was mainly determined by a combination of microbial degradation and biochar surface adsorption. This study provides a method for preparing an efficient biochar-microbial complex using Chinese medicine residue waste substrate, which provides a new idea for removing chlortetracycline from water.
106. 题目: Dissolved Black Carbon and Semivolatile Aromatic Hydrocarbons in the Ocean: Two Entangled Biogeochemical Cycles?
期刊: Environmental Science & Technology Letters
作者: Núria Trilla-Prieto, Maria Vila-Costa, Gemma Casas, Begoña Jiménez, Jordi Dachs
摘要: Dissolved black carbon (DBC) plays a role in the oceanic carbon cycle. DBC originates from the heating and incomplete combustion of organic matter, including fossil fuels, a shared origin with polycyclic aromatic hydrocarbons (PAH). DBC is quantified using the benzene polycarboxylic acids produced by oxidation of the organic extract, a fraction of which derive from PAHs and other semivolatile aromatic-like compounds (SALCs). However, the current view of the DBC cycle does not take into account the inputs and sinks known for PAHs, such as diffusive air–water exchange and degradation. A meta-analysis of oceanic PAHs, SALCs, and DBC concentrations shows that SALCs account for 16% of DBC (ranging from 5% to 31%). Such a large contribution of semivolatile aromatic hydrocarbons to DBC is consistent with the large atmospheric input of SALCs (estimated as 400 Tg C y–1). Furthermore, photodegradation at the surface ocean and microbial degradation in the water column of semivolatile DBC can be important sinks, consistent with the ubiquitous occurrence of the degradation genes of the metabolic routes for aromatic hydrocarbons. Future work should focus on the characterization of semivolatile DBC and its degradation in order to constrain its contribution to refractory organic matter and the anthropogenic perturbation of the carbon cycle.
107. 题目: Warming and humidification mediated changes of DOM composition in an Alfisol
期刊: Science of The Total Environment
作者: Yafeng Han, Chenchen Qu, Xiping Hu, Peng Wang, Dan Wan, Peng Cai, Xingmin Rong, Wenli Chen, Qiaoyun Huang
摘要: Dissolved organic matter (DOM) represents the most mobile and reactive pool of soil organic matter (SOM). Climate changes, such as global warming and altered precipitation exert considerable influences on the quality and quantity of soil DOM. However, rare reports have focused on the interactive effects of soil warming and increased precipitation. In the present study, we conducted a 90–day incubation experiment to investigate how the concentration, source and chemical composition of DOM from an Alfisol respond to the variations of temperatures (15, 30 and 45 °C) and moistures (40%, 60%, and 80% of saturated soil water content). Four DOM components were identified through fluorescence excitation emission matrix (EEM)–parallel factor analysis (PARAFAC). Increased temperature alone aggravated the decomposition of plant–derived aromatic components (C2 and C4) but promoted the accumulation of microbial–derived aliphatic carbon (C1) and tryptophan–like component (C3). Increased fungi/bacteria ratio with warming was responsible for the decomposition of plant–derived components. Warming–induced disassociation of Ca–bearing mineral to colloidal Ca facilitated the accrual of microbial–derived aliphatic DOM. Humidification alone and humidification + warming significantly increased the concentration of DOM and the percentage of plant–derived aromatic carbon (C2, C4), which was attributed to the release of Fe–bearing mineral–OC. Accompanying above findings with the results of two–way ANOVA and Variation partition analysis, we found that humidification, rather than warming, may modify considerably the quantity and chemodiversity of DOM in Alfisols under climate changes which in turn impact global C cycling and the ultimate climate.
108. 题目: One-Step Synthesis of ZnFe2O4-Loaded Biochar Derived from Leftover Rice for High-Performance H2S Removal
期刊: Separation and Purification Technology
作者: Yi Yuan, Lijia Huang, Tian C. Zhang, Like Ouyang, Shaojun Yuan
摘要: Hydrogen sulfide (H2S) is a major air pollutant posing a serious threat to the environment and public health. It is highly attractive to develop state-of-the-art adsorbent to remove H2S. Herein, a novel ZnFe2O4-loaded porous biochar (RZF) with a high surface area of 1065 m2/g was synthesized via one-step carbonation activation of kitchen leftover rice with ZnCl2 and FeCl3 as activators. The optimized RZF-500-1:1 was obtained by rationally adjusting the activation ratio (the mass ratio of leftover rice and ZnFe2O4) and pyrolysis temperature. Such RZF-500-1:1 delivered high-performance H2S removal with the breakthrough capacity up to 228.29 mg/g at 25°C, whilst the inactivated biochar (carbonization without activator) only showed a much lower adsorption capacity at circa 12.11 mg/g of H2S. The desulfurization conditions had a significant effect on the H2S breakthrough capacity, and the adsorbent exhibited better desulfurization performance at room temperature and in the presence of oxygen. The desulfurization mechanism on the ZnFe2O4-loaded biochar was proposed to be an adsorption-catalytic oxidation coupled process. Moreover, the as-fabricated sample showed high regeneration ability, retaining 91.6% of the initial breakthrough capacity after five regeneration cycles. This novel one-step preparation method would permit a gain of time and energy to obtain efficient activated carbons intended to capture H2S.
109. 题目: Biochar effectively inhibits the horizontal transfer of antibiotic resistance genes via transformation
期刊: Journal of Hazardous Materials
作者: Jing Fang, Liang Jin, Qingkang Meng, Shengdao Shan, Dengjun Wang, Daohui Lin
摘要: The rapid spread of antibiotic resistance genes (ARGs) has posed a risk to human health. Here, the effects of biochar (BC) on the horizontal transfer of ARG-carrying plasmids to Escherichia coli via transformation were systematically investigated. BC could significantly inhibit the transformation of ARGs and the inhibition degree increased with pyrolysis temperature. Rice straw-derived BC showed a stronger inhibitory effect on the transformation of ARGs than that of peanut shell-derived BC from the same pyrolysis temperature. The inhibitory effect of BC from low pyrolysis temperature (300 ℃) was mainly caused by BC dissolutions, while it was mainly attributed to BC solids for high pyrolysis temperature (700 ℃) BC. BC dissolutions could induce intramolecular condensation and even agglomeration of plasmids, hindering their transformation into competent bacteria. The cell membrane permeability was slightly decreased in BC dissolutions, which might also contribute to the inhibitory effect. Plasmid can be adsorbed by BC solids and the adsorption increased with BC pyrolysis temperature. Meanwhile, BC-adsorbed plasmid could hardly be transformed into E. coli. BC solids could also deactivate E. coli and thereby inhibit their uptake of ARGs. These findings provide a way using BC to limit the spread of ARGs in the environment.
110. 题目: Solid-liquid separation of real cellulose- containing wastewaters by extracellular polymeric substances: mechanism and cost evaluation
期刊: Separation and Purification Technology
作者: Rui Zhang, Zhong-yue Chang, Ling-ling Wang, Wei-xin Cheng, Rong-ping Chen, Lei Yu, Xu-hai Qiu, Jian-gang Han
摘要: The flocculation feasibilities of tobacco wastewater (TBW) and livestock and poultry wastewater (LPW) by the extracellular polymeric substances (EPS) of Bacillus sp. were evaluated in this study. The average particle sizes of flocs formed by crude EPS were 45.83 and 41.67 mm in TBW and LPW, respectively, which were larger than that formed by chemical flocculants. The removal efficiencies of chemical oxygen demand, ammonia nitrogen and suspended solid achieved by crude EPS were increased more than 50% than that by chemical flocculants. Charge neutralization was dominant in the flocculation of LPW, while chemical reactions between the Fe(III) and reductive substances in TBW played an important role in the flocculation of TBW. The FTIR and XPS results indicated that the sugar derivatives of EPS, especially the hemiacetal and glucoside groups interacted with cellulose molecules. Three-dimensional EEM fluorescence spectra presented three peaks of tryptophan protein, aromatic polysaccharides and polysaccharides, and the peak intensities were enhanced with the addition of cellulose by PARAFAC analysis. Cost evaluation suggested that the generated flocs and supernatants could be further utilized as fertilizer after the solid-liquid separation of LPW, thus one ton of LPW after flocculation by crude EPS might generate a gross profit of $43.51, suggesting that advantages of crude EPS not only on environmental protection but also on flocculation cost. The results implied that the crude EPS of Bacillus sp. have stronger competitiveness in the treatment of cellulose-containing wastewaters comparing to the chemical flocculants, which sheds lights on its potential usage as an alternative bio-flocculant.
111. 题目: Effects of Ca 2+ on migration of dissolved organic matter in limestone soils of the southwest China karst area
期刊: Land Degradation & Development
作者: Peiwen Xiao, Baohua Xiao, Muhammad Adnan
摘要: The prospect of carbon sequestration in soils of karst areas remains unclear. The study on migration and transformation of dissolved organic matter (DOM) in limestone soil under the high calcium environment of karst region content was seldom reported. This study conducted soil column experiments on two surface soils (H1 and S2) and two sub-surface soils (H2 and S2) from two limestone soil profiles in the karst region of southwest China and investigated their DOM leaching behaviors under different Ca2+ concentration levels. The results showed that the DOM leaching process can be described by the Elovich equation, including a rapid DOM release stage and the relatively stable DOM release stage. When the Ca2+ concentration of eluent increases from 0 to 2.5â€‰mmol L-1, the percentage of dissolved organic carbon (DOC) loss in H1, H2, S1 and S2 soils decreased from 66.3% to 58.8%, from 76.2% to 72.4%, from 73.0% to 68.8% and from 52.5% to 46.6%, respectively, and the apparent molecular weight and aromaticity of leached DOM increases, the contribution of humic-like components decreases. The results further show that the influence of Ca2+ on easily leaching DOM is stronger than that on the stable DOM, indicating that high Ca2+ runoff can enrich high aromaticity and high molecular weight soil organic matter (SOM) in the limestone soil during the leaching process. This research is helpful to understand the migration and fate of SOM in limestone soils and provides theoretical support for increasing soil carbon sinks in karst areas.
112. 题目: Differences in the flow of spruce-derived needle leachates and root exudates through a temperate coniferous forest mineral topsoil
作者: Veronika Jílková, Kateřina Jandová, Tomáš Cajthaml, Jaroslav Kukla, Jan Jansa
摘要: Coniferous forest ecosystems are important pools of soil organic carbon (SOC) in the Northern temperate zone. Needle leachates and root exudates represent a significant input of C to these soils and can differently affect soil C cycling because of their differences in chemistry and stoichiometry. This is the first study to investigate the differences in the flow of dissolved organic C (DOC) in the form of needle leachates, root exudates, and their combination through a forest mineral topsoil. We conducted a 5-month microcosm experiment with ecologically relevant additions of 13C-labelled spruce-derived substrates. The proportion of DOC lost from or incorporated into the mineral soil as microbial biomass or soil fractions (free, occluded by or adsorbed onto mineral particles) as well as differences in the priming effect (PE) caused by the two substrates were assessed. Needle leachates (higher in phenolics and C:N ratio) were less utilized by the microbial community than root exudates but caused a higher PE probably because they lacked sufficient N to satisfy microbial N demands. The addition of either substrates failed to change microbial community composition or SOC content in soil fractions. Most of the substrate C in soil fractions was stabilized by adsorption onto mineral particles. On average, 69% of the substrate C was lost via mineralization; only 0.23% via leaching. The most important C pool related to substrate C gain was the C stored in soil fractions (29%); only 1.7% was stored in the microbial biomass. A consideration of all C gains and losses indicates that the addition of spruce-derived substrates resulted in an average net substrate C retention of 31%.
113. 题目: Co-precipitation induces changes to iron and carbon chemistry and spatial distribution at the nanometer scale
期刊: Geochimica et Cosmochimica Acta
作者: Angela R. Possinger, Michael J. Zachman, James J. Dynes, Tom Z. Regier, Lena F. Kourkoutis, Johannes Lehmann
摘要: Association of organic matter (OM) with mineral phases via co-precipitation is expected to be a widespread process in environments with high OM input and frequent mineral dissolution and re-precipitation. In contrast to surface area-limited adsorption processes, co-precipitation may allow for greater carbon (C) accumulation. However, the potential sub-micrometer scale structural and compositional differences that affect the bioavailability of co-precipitated C are largely unknown. In this study, we used a combination of high-resolution analytical electron microscopy and bulk spectroscopy to probe interactions between a mineral phase (ferrihydrite, nominally Fe2O3•0.5H2O) and organic soil-derived water-extractable OM (WEOM). In co-precipitated WEOM-Fe, nanometer-scale scanning transmission electron microscopy with electron energy loss spectroscopy (STEM-EELS) revealed increased Fe(II) and less Fe aggregation relative to adsorbed WEOM-Fe. Spatially distinct lower- and higher-energy C regions were detected in both adsorbed and co-precipitated WEOM-Fe. In co-precipitates, lower-energy aromatic and/or substituted aromatic C was spatially associated with reduced Fe(II), but higher-energy oxidized C was enriched at the oxidized Fe(III) interface. Therefore, we show that co-precipitation does not constitute a non-specific physical encapsulation of C that only affects Fe chemistry and spatial distribution, but may cause a bi-directional set of reactions that lead to spatial separation and transformation of both Fe and C forms. In particular, we propose that abiotic redox reactions between Fe and C via substituted aromatic groups (e.g., hydroquinones) play a role in creating distinct co-precipitate composition, with potential implications for its mineralization.
114. 题目: Using stable isotopes and chemical markers to understand the history of Negombo Lagoon, Sri Lanka
期刊: Organic Geochemistry
作者: Carolina P. Funkey, Vajira A. Waduge, Nalaka P. Ranasinghe, Harshanie S. Dasanayaka, Imma Tolosa
摘要: Negombo Lagoon is a highly valued estuary in Sri Lanka due to its high socioeconomic value, but this estuary has undergone many changes since the early 1800s due to human impact. Records of carbon and nitrogen stable isotopes, and alkane, alcohol, polycyclic aromatic hydrocarbon (PAH) and hopane biomarkers from the mid-19th century to 2012 in a sediment core collected from Negombo Lagoon indicate that the lagoon went through two major changes during this 160-year time frame. The first change occurred from 1850-1900, where a switch from predominately terrestrial sources of organic material to marine sources is observed, after the Hamilton Canal was built in 1804 to connect the open ocean to the lagoon. The second change occurred post 1940s during Sri Lanka’s industrialization period where high anthropogenic inputs are seen in the estuary, specifically as increases in PAHs and oil-related, diagenetic hopanes. Overall, the Negombo Lagoon appears to be moderately polluted by PAHs with the highest concentrations of parent PAHs measured in the 1980s and likely derived from pyrolytic sources of solid fuel biomass.
115. 题目: Development and Optimization of Bioretention Systems with Modified Fillers of Corn Straw Biochar
期刊: Water, Air, & Soil Pollution
作者: Jiake Li, Ning Li, Fang Liu, Yajiao Li
摘要: Bioretention systems have been proved to be a natural approach for effectively reducing stormwater runoff pollution loads. The filler is essential for the function of the bioretention systems; there are few studies on the use of biochar for bioretention. In this study, corn straw was used as raw material to prepare biochar bioretention-improved filler, and the optimal preparation scheme and filler proportioning method were determined. Three layered bioretention columns, i.e., BSM (bioretention soil media), BSM + 5%WTR (water treatment residues, w/w) and BSM + 5%CSC (corn straw biochar, w/w), were built to analyze its regulating effect on rainwater runoff. The DRAINMOD model was established based on the test results to analyze the regulating effect in different situations. The key parameters of the bioretention systems were optimized using response surface methodology (RSM). The results show that: BSM + 5%CSC was more stable than BSM + 5%WTR for water volume control effect and was better than BSM. The load reduction rates of BSM + 5%CSC was better than that of BSM and BSM + 5%WTR. When only considering the optimal nitrogen reduction effect, it was necessary to deepen the depth of the submerged area to improve the nitrogen control effect. When considering the optimal control effects of water volume and nitrogen, the thickness of the filler layer was the key factor affecting the water reduction rate. Overall, this study demonstrated that corn straw biochar can effectively improve the regulation effect of bioretention systems, and the optimization of parameters can provide references for the design of bioretention systems.
116. 题目: Mechanistic insights into Cd(II) and As(V) sorption on Miscanthus biochar at different pH values and pyrolysis temperatures
作者: Seoyeon Lee, Junho Han, Hee-Myong Ro
摘要: Biochar has received great attention as a biosorbent, but explanations of the underlying sorption mechanisms are still unclear. Here, batch sorption of cadmium (Cd(II)) and arsenate (As(V)) to Miscanthus biochar at different pH values and pyrolysis temperatures and the sorption mechanisms were comprehensively investigated. The maximum sorption capacities for both Cd(II) and As(V) were observed under alkaline conditions. Physisorption was identified as a common sorption mechanism for both Cd(II) and As(V) irrespective of pH; however, inner-sphere complexation with acidic functional groups (AFGs) and crystallized precipitation as otavite predominate at higher pH values for Cd(II), while hydrophobic attraction of arsenite and metallic As and electrostatic bridging with multivalent ions at deprotonated AFGs are presumed to be dominant sorption mechanisms for As(V). Inner-sphere complexes of Cd(II) (98.6%) and electrostatic bridging complexes of As(V) (89.5%) were the dominant sorption forms for B400, while inner-sphere complexes (45.9%) and precipitates (50.5%) of Cd(II) and physisorption and hydrophobic interactions of As (63.7%) were abundant. The results challenge the widely held notion that the sorption of anions decreases as pH increases, while that of cations increases with increasing pH. This unexpected phenomenon can be explained by reduction of As(V) and by the difference in the charge densities between As(V) and basic functional groups of the biochar. Such biochar-induced reduction would cause an unexpected risk of exposing human health and ecosystems to reduceable pollutants. These findings contribute to a better explanation for the environmental fate and behavior of inorganic pollutants in biochar applications.
117. 题目: Modified soil physicochemical properties promoted sequestration of organic and inorganic carbon synergistically during revegetation in desertified land
期刊: Journal of Environmental Chemical Engineering
作者: Jiao Li, Mukesh Kumar Awasthi, Qiong Zhu, Xiaoyu Chen, Faqi Wu, Fuyong Wu, Xiaogang Tong
摘要: Large-scale revegetation in desertified land might promote the sequestration of global soil carbon, but the influencing factors on inorganic carbon accumulation processes that absorb CO2 through abiotic “inorganic respiration” processes remain unclear. Several study sites were selected in the Mu Us Sandy Land: quicksand land (0 years), semi-fixed sand land (6 years), and three nearby shrub and arbor forest lands (20, 30, and 51 years). During 20-51 years of revegetation, soil organic carbon density (SOCD) and inorganic carbon density (SICD) significantly increased by 2.5-7.5 times and 1.7-7.0 times for shrub forest and 3.1-7.5 times and 2.6-7.8 times for arbor forest compared with quicksand land, but the difference between the two studied forest lands were not statistically significant. After revegetation in desertified land, the content of total nitrogen (TN), available potassium (AK), cation exchange capacity (CEC), clay, Ca2+, and Mg2+ also greatly enhanced, and they were positively correlated with SOC and SIC, while bulk density and pH slightly decreased, which were negatively correlated with SOC and SIC. T-value biplot importance ranking further indicated that TN was the most sensitive factor affecting the accumulation of SOC and SIC, and its contribution rate to SOC and SIC reached 89.8% and 88.1%, respectively. Moreover, SOC was also related to AK, CEC, and clay, while SIC was more affected by clay, Ca2+, and Mg2+ during revegetation. In conclusion, afforestation with shrubs and arbors on the Mu Us Sandy Land promoted the sequestration of SOC and SIC synergistically by modified soil physicochemical properties.
118. 题目: Biochar as a novel carbon-negative electron source and mediator: electron exchange capacity (EEC) and environmentally persistent free radicals (EPFRs): A review
期刊: Chemical Engineering Journal
作者: Jieming Yuan, Yinghao Wen, Dionysios D. Dionysiou, Virender K. Sharma, Xingmao Ma
摘要: Biochar is the pyrolysis product of biomass that has been explored as an effective adsorbent for its high specific surface area, large porosity, and numerous surface functional groups. Recently, there is a renewed interest in biochar thanks to the recognition of its strong electron exchange capacity (EEC), which enables it to store and shuttle electrons to break down contaminants. Environmentally persistent free radicals (EPFRs) are an inherent property of biochar, and have been found to be an important contributing factor of the biochar EEC due to its strong electron donating capacity. This review provides a compressive analysis of recent advances in the EEC of biochar, focusing primarily on the mechanisms of EEC formation, factors affecting it and biochar applications in environmental cleanup. Pyrolysis temperature and properties of feedstock materials are two dominant factors governing the EEC of biochar. The temperature is important because it affects the characteristics of oxygen functional groups (OFGs) in biochar and high pyrolysis temperature (> 600 oC) will graphitize carbon which shuttles electrons but does not directly participate in redox reactions. The impact of feedstock on biochar mainly derives from the differences in feedstock compositions which contain different OFGs. Following the elucidation of the EEC formation and stability, applications of biochar as an electron mediator are given, and main knowledge gaps and research needs to further advance the understanding and applications of biochar EEC are discussed.
119. 题目: Emerging onsite electron donors for advanced nitrogen removal from anammox effluent of leachate treatment: A review and future applications
期刊: Bioresource Technology
作者: Yanyan Li, Yanxu Liu, Jinghuan Luo, Yu-You Li, Jianyong Liu
摘要: Partial nitrification-anammox process is promising in leachate treatment, but the 11% residue nitrate limits the total nitrogen removal efficiency. Denitrification or partial denitrification and anammox are both practical polishing processes of anammox effluent, requiring extra electron donors. Fortunately, there are organic matter, sulfide and methane in leachate or produced by leachate treatment, which can serve as onsite electron donors. In this review, the mechanisms and processes using these three kinds of electron donors for residue nitrate reduction in anammox effluent of leachate are systematically summarized and discussed. It can be concluded that, biodegradable organic matter is an effective electron donor, sulfide is a promising electron donor, methane is a potential electron donor. Two possible applications in future based on anammox treatment of fresh and mature leachate using sulfide and methane as onsite electron donors are proposed. Through sulfide reutilization, energy-saving with about 14% of aeration reduction can be achieved.
120. 题目: Biochar reduced extractable dieldrin concentrations and promoted oligotrophic growth including microbial degraders of chlorinated pollutants
期刊: Journal of Hazardous Materials
作者: Christian Krohn, Pei Zhang, Jennifer L. Wood, Helen L. Hayden, Ashley E. Franks, Jian Jin, Caixian Tang
摘要: The role of organic amendments for natural degradation of aged persistent organic pollutants (POPs) in agricultural soils remains controversial. We hypothesised that organic amendments enhance bacterial activity and function at the community level, facilitating the degradation of aged POPs. An incubation study was conducted in a closed chamber over 12 months to assess the effects of selected organic amendments on extractable residues of aged dieldrin. The role of bacterial diversity and changes in community function was explored through sequenced marker genes. Linear mixed effect models indicated that, independent of amendment type, cumulative CO2 respiration was negatively associated with decreases in dieldrin concentration, by up to 7% per µmol CO2−C respired by microorganisms. The addition of poultry litter led to the highest daily carbon mineralisation, which was associated with low dieldrin dissipation after 9 months. In comparison, biochar resulted in significant decreases in extractable dieldrin residues over time, which coincided with shifts towards aerobic, oligotrophic, gram-negative bacteria, some with dehalogenation metabolism, and with increased potentials for biosynthesis of membrane components such as fatty acids and high redox quinones. The results supported an alternative theory that labile carbon promoted blooms of copiotrophic growth, which suppressed the required community-level traits and oligotrophic diversity to degrade chlorinated pollutants.