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25641. 题目: Evaluation of biochar properties exposing to solar radiation: A promotion on surface activities
文章编号: N19122614
期刊: Chemical Engineering Journal
作者: Neng Li, Fei Rao, Lili He, Shengmao Yang, Yongjie Bao, Chengjian Huang, Minzhen Bao, Yuhe Chen
更新时间: 2019-12-26
摘要: Biochar is an important bio-material used to mitigate environmental and agronomic problems. The complex outdoor environment, which includes exposure to solar radiation, greatly influences biochar structure, which in turn impacts its functions when it is used in outdoors. The objective of this study is to understand the dynamics associated with the physical and chemical changes that occur in bamboo biochar (BB) prepared at different final temperatures during exposure to damaging radiation. The basic physical and chemical properties of fresh and accelerated weathered BBs were investigated by measuring the chemical element, ash content, BET surface area, color changes. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetry analysis and differential scanning calorimetry were used to determine the changes in functional groups, the variation in the surface element species distribution and the differences in thermochemical property of BBs. The experimental results showed that clear changes in BBs were obtained after 400 h of accelerated weathering. The C and N contents of BBs declined, and its O content increased. The average changes in color and decrease in residue yield of BBs were 1.02 and 1.58%, respectively. The average growth rates of O/C ratio (determined by elemental analysis), C4, and O2 of BBs were 17.04%, 13.88% and 86.63%, respectively. These results illustrate that the BBs underwent a series of photooxidation reactions when exposed to UV radiation. The increase of surface oxygen-containing functional groups may improve the surface activities of BB with respect to soil-amelioration applications, pollutant-degradation efficiency and the adsorbability toward aqueous contaminants.
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25642. 题目: Biochar amendment effectively reduces the transport of 3,5,6-trichloro-2-pyridinol (a main degradation product of chlorpyrifos) in purple soil: Experimental and modeling
文章编号: N19122613
期刊: Chemosphere
作者: Wenjuan Lei, Xiangyu Tang, Xiangyang Zhou
更新时间: 2019-12-26
摘要: This study investigates biochar amendment effectively reduces the transport of polar pollutant 3,5,6-trichloro-2-pyridinol, TCP, a main degradation product of chlorpyrifos, and quantitatively explores the physical and chemical mechanisms through inversion simulation. Thus, five biochar addition rates to soil, 0.0%, 0.5%, 1.0%, 2.5% and 5.0%, are tested and compared. The adsorption isotherms experiment, breakthrough curves, BTCs, in both repacked and undisturbed soil columns are also compared. And finally the non-equilibrium convection-diffusion equation, CDE, is used to uncover the change of hydraulic properties of soil and mass non-equilibrium of TCP in the soils mixed with different contents of biochar. The results show that the addition of biochar can reduce the transportation of TCP significantly in the purple soil with macro pores, and the reduction is mainly attributed to two aspects: increase of adsorption ability and decrease of diffusion coefficient and convection velocity. The former is reflected by the linear increase of K_d value with the increase of biochar addition rate and soil organic matter content. The latter is demonstrated by the dramatic reduction of TCP concentration in outflow of BTC experiment and the delayed leaching time. The inversely simulated results also reveal that the diffusion coefficient decrease from 5.35 to 3.95 when biochar addition rate increases from 0 to 5%. Compared with the repacked soil columns, the preferential flow does not disappear in the undisturbed soil columns, accompanied by a higher maximum concentration, an earlier equilibrium time and a less residual amount.

25643. 题目: Coagulation and disinfection by-products formation potential of extracellular and intracellular matter of algae and cyanobacteria
文章编号: N19122612
期刊: Chemosphere
作者: Ziming Zhao, Wenjun Sun, Ajay K. Ray, Ted Mao, Madhumita B. Ray
更新时间: 2019-12-26
摘要: Coagulation and flocculation can remove particulate algal cells effectively; however, they are not very effective for removing dissolved algal organic matter (AOM) in drinking water plants. In this work, optimum coagulation conditions using alum for both extracellular and intracellular organic matter of six different algal and cyanobacterial species were determined. Different coagulation conditions such as alum dosage, pH, and initial dissolved organic carbon (DOC) were tested. Hydrophobicity, hydrophilicty, and transphilicity of the cellular materials were determined using resin fractionation method. The removal of DOC by coagulation correlated well with the hydrophobicity of the AOM. The disinfection by-product formation potential (DBPFP) of various fractions of AOM was determined after coagulation. Although, higher removal occurred for hydrophobic AOM during coagulation, specific DBPFP, which varied from 10 to 147 μg/mg-C was higher for hydrophobic AOM. Of all the six species, highest DBPFP occurred for Phaeodactylum tricornutum, an abundant marine diatom species, but is increasingly found in surface water.

25644. 题目: Benefits of ozonation before activated carbon adsorption for the removal of organic micropollutants from wastewater effluents
文章编号: N19122611
期刊: Chemosphere
作者: Ronan Guillossou, Julien Le Roux, Stéphan Brosillon, Romain Mailler, Emmanuelle Vulliet, Catherine Morlay, Fabrice Nauleau, Vincent Rocher, Johnny Gaspéri
更新时间: 2019-12-26
摘要: Advanced processes for the removal of organic micropollutants (OMPs) from wastewater effluents include adsorption onto activated carbon, ozonation, or a combination of both processes. The removal of 28 OMPs present in a real wastewater effluent was studied by ozonation coupled to activated carbon adsorption and compared to a sole adsorption. The influence of the specific ozone dose (0.09–1.29 gO₃/gDOC) and the influence of the powdered activated carbon (PAC) dose (2, 5 and 10 mg/L) were first studied separately. OMPs removal increased with both the specific ozone dose (up to 80% for a dose higher than 0.60 gO₃/gDOC) and the PAC dose. Ozonation performances decreased in presence of suspended solids, which were converted to dissolved organic carbon. A correction of the specific ozone dose according to the suspended solids levels, in addition to nitrite, should be considered. The influence of ozonation (0.09, 0.22, 0.94 and 1.29 gO₃/gDOC) on OMPs adsorption was then assessed. OMPs adsorption didn’t change at low specific ozone doses but increased at higher specific ozone doses due to a decrease in DOM adsorption and competition with OMPs. At low ozone doses followed by adsorption (0.22 gO₃/gDOC and 10 mg/L PAC), the two processes appeared complementary as OMPs with a low reactivity toward ozone were well absorbed onto PAC while most OMPs refractory to adsorption were well eliminated by ozone. Improved removals were obtained for all compounds with these selected doses, reaching more than 80% removal for most OMPs while limiting the formation of bromate ion.
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25645. 题目: Biochar and manure addition influenced soil microbial community structure and enzymatic activities at eroded and depositional landscape positions
文章编号: N19122610
期刊: Land Degradation & Development
作者: Udayakumar Sekaran, Saroop S. Sandhu, Yeyan Qiu, Sandeep Kumar, Jose L. Gonzalez Hernandez
更新时间: 2019-12-26
摘要: Biochar and manure application can modify soil microbial community structure and enhance biochemical activities. However, the studies about the influence of biochar and manure on the microbial communities on different geomorphological landforms (depositional and eroded landscapes) are scarce. In this study, we investigated the responses of soil biochemical activities and microbial communities to the addition of pinewood biochar, dairy manure (DM), and the dairy manure and pinewood biochar mixture (DMP) at a rate of 10 Mg ha⁻¹, respectively, in comparison with control (CNT) at eroded and depositional landscape positions over 5 years. Data showed that the DMP treatment significantly increased cold‐water‐soluble organic carbon and hot‐water‐soluble organic carbon at the depositional landscape than CNT soils. Application of DMP increased total phospholipid fatty acid (PLFA) and bacterial PLFA by 31% and 20% compared with the CNT at the depositional landscape, respectively. At eroded landscape, total PLFAs and total bacterial PLFAs biomass concentrations were found 39% and 90% higher with DM than CNT soils. The addition of DM and DMP increased the activities of enzymes that are involved in the major nutrient cycling at depositional and eroded landscapes. At the phylum level, the proportion of Bacteroidetes was found lower in DMP, but the proportion of phylum Proteobacteria and Acidobacteria were increased. In conclusion, our study revealed that DMP influenced the labile nutrient pool, altered the microbial community structure, and increased bacterial composition and enzymatic activities at both the landscape positions.

25646. 题目: Spatial patterns in soil organic matter dynamics are shaped by mycorrhizosphere interactions in a treeline forest
文章编号: N19122609
期刊: Plant and Soil
作者: Nina L. Friggens, Thomas J. Aspray, Thomas C. Parker, Jens-Arne Subke, Philip A. Wookey
更新时间: 2019-12-26
摘要: Aims: In the Swedish sub-Arctic, mountain birch (Betula pubescens ssp. czerepanovii) forests mediate rapid soil C cycling relative to adjacent tundra heaths, but little is known about the role of individual trees within forests. Here we investigate the spatial extent over which trees influence soil processes. Methods: We measured respiration, soil C stocks, root and mycorrhizal productivity and fungi:bacteria ratios at fine spatial scales along 3 m transects extending radially from mountain birch trees in a sub-Arctic ecotone forest. Root and mycorrhizal productivity was quantified using in-growth techniques and fungi:bacteria ratios were determined by qPCR. Results: Neither respiration, nor root and mycorrhizal production, varied along transects. Fungi:bacteria ratios, soil organic C stocks and standing litter declined with increasing distance from trees. Conclusions: As 3 m is half the average size of forest gaps, these findings suggest that forest soil environments are efficiently explored by roots and associated mycorrhizal networks of B. pubescens. Individual trees exert influence substantially away from their base, creating more uniform distributions of root, mycorrhizal and bacterial activity than expected. However, overall rates of soil C accumulation do vary with distance from trees, with potential implications for spatio-temporal soil organic matter dynamics and net ecosystem C sequestration.

25647. 题目: Remote sensing estimation of colored dissolved organic matter (CDOM) from GOCI measurements in the Bohai Sea and Yellow Sea
文章编号: N19122608
期刊: Environmental Science and Pollution Research
作者: Zunbin Ling, Deyong Sun, Shengqiang Wang, Zhongfeng Qiu, Yu Huan, Zhihua Mao, Yijun He
更新时间: 2019-12-26
摘要: Colored dissolved organic matter (CDOM) is the main constituent of dissolved organic matter (DOM), also a key indicator of water quality conditions. Accurate estimation of CDOM is essential for understanding biogeochemical processes and ecosystems in marine waters. The use of remote sensing to derive the changes in CDOM is vital technology that can be used to dynamically monitor the marine environment and to document the spatiotemporal variations in CDOM over a large scale. In the present study, we develop a simple approach to estimate the CDOM concentrations based on the in situ datasets from four cruise surveys over the Bohai Sea (BS) and Yellow Sea (YS). Eight band combination forms (using Xi as a delegate, where i denotes the numerical order of band combination forms), including single bands, band ratios, and other band combinations by remote sensing reflectance, R_rs(λ), were trained to test the correlations with the CDOM concentrations. The obtained results indicated that X7, i.e., [R_rs(443) + R_rs(555)]/[R_rs(443)/R_rs(555)], was the optimal form, with correlation coefficient (R) values of 0.904 (p < 0.001). The X7-based fitting model was determined as the optimal model by the leave-one-out cross-validation method with relatively low estimation errors (mean relative error, MRE, 20%), and satellite match-up validation with in situ measurements indicated good performance MRE = 20.3%). Moreover, two spatial distribution patterns of CDOM in Jan. 2017 and Apr. 2018 (independent data) retrieved from Geostationary Ocean Color Imager (GOCI) data agreed well with those in situ observations. These results indicate that our proposed algorithm is feasible and robust for retrieving CDOM concentrations in this study region. In addition, we applied this method to GOCI data for the whole 2016 year in the BS and YS and produced the spatial distribution patterns from different temporal scales including monthly, seasonal, and annual scales. Overall, the findings of this study motivate the development and application of a simple but effective method of the CDOM estimation for those optically complex turbid coastal waters, like this study water areas.

25648. 题目: Chlorophyll-a, dissolved organic carbon, turbidity and other variables of ecological importance in river basins in southern Ontario and British Columbia, Canada
文章编号: N19122607
期刊: Environmental Monitoring and Assessment
作者: K. Zolfaghari, G. Wilkes, S. Bird, D. Ellis, K. D. M. Pintar, N. Gottschall, H. McNairn, D. R. Lapen
更新时间: 2019-12-26
摘要: Optical sensing of chlorophyll-a (chl-a), turbidity, and fluorescent dissolved organic matter (fDOM) is often used to characterize the quality of water. There are many site-specific factors and environmental conditions that can affect optically sensed readings; notwithstanding the comparative implication of different procedures used to measure these properties in the laboratory. In this study, we measured these water quality properties using standard laboratory methods, and in the field using optical sensors (sonde-based) at water quality monitoring sites located in four watersheds in Canada. The overall objective of this work was to explore the relationships among sonde-based and standard laboratory measurements of the aforementioned water properties, and evaluate associations among these eco-hydrological properties and land use, environmental, and ancillary water quality variables such as dissolved organic carbon (DOC) and total suspended solids (TSS). Differences among sonde versus laboratory relationships for chl-a suggest such relationships are impacted by laboratory methods and/or site specific conditions. Data mining analysis indicated that interactive site-specific factors predominately impacting chl-a values across sites were specific conductivity and turbidity (variables with positive global associations with chl-a). The overall linear regression predicting DOC from fDOM was relatively strong (R² = 0.77). However, slope differences in the watershed-specific models suggest laboratory DOC versus fDOM relationships could be impacted by unknown localized water quality properties affecting fDOM readings, and/or the different standard laboratory methods used to estimate DOC. Artificial neural network analyses (ANN) indicated that higher relative chl-a concentrations were associated with low to no tree cover around sample sites and higher daily rainfall in the watersheds examined. Response surfaces derived from ANN indicated that chl-a concentrations were higher where combined agricultural and urban land uses were relatively higher.

25649. 题目: Biochar induced modification of graphene oxide & nZVI and its impact on immobilization of toxic copper in soil
文章编号: N19122606
期刊: Environmental Pollution
作者: Sandip Mandal, Shengyan Pu, Lingling He, Hui Ma, Deyi Hou
更新时间: 2019-12-26
摘要: Biochar has recently been fascinating for research in many environment areas due to its potential applications. In this research, graphene, and nano zero-valent iron (nZVI) is integrated with biochar and used for copper immobilization in the soil. Initially, the biomass feedstock was pyrolyzed under N₂ atmosphere from 150 to 650 °C and immersed in an aqueous solution containing graphene and further impregnated with nZVI. Laboratory characterization with different instruments (SEM, TEM, XRD, UV–Vis, VSM, and XPS) and methods showed that graphene sheets and reactive nZVI were loaded on the biochar surface during the development process. 450 °C was considered as optimum temperature based on the effective surface properties of the obtain biochar material. Boehm titration and functional group analysis confirmed the presence of carboxylic groups, phenolic groups in the corn stack biochar supported graphene oxide/nZVI (CTBC-GO/nZVI). Thermogravimetric analysis showed that nZVI incorporation to biochar surface could improve thermal stability as compared to graphene oxide incorporated biochar and pristine biochar. The material was utilized for copper (Cu) immobilization in the soil and a comparative evaluation was established on the basis of efficiency. The soil experiment showed that the CTBC-GO/nZVI had a more obvious effect on the immobilization of copper than ordinary biochar and GO@BC. The available Cu content decreased by > 65% in CTBC-GO/nZVI amended soil after 14 days. Sequential extraction procedure (SEP) results suggested that CTBC-GO/nZVI promoted the conversion of more accessible Cu into the less accessible and bioavailable forms to reduce the toxicity of Cu. Therefore, CTBC-GO/nZVI composite is a promising and effective amendment for immobilizing Cu in contaminated soils and improving soil properties.This work can put forward a strategy to develop magnetic biochar composites and application towards toxic heavy metals immobilization in the soil.
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25650. 题目: Formation mechanisms of emerging organic contaminants during on-line membrane cleaning with NaOCl in MBR
文章编号: N19122605
期刊: Journal of Hazardous Materials
作者: Weiwei Cai, Jiarui Han, Xiangru Zhang, Yu Liu
更新时间: 2019-12-26
摘要: On-line chemical cleaning with sodium hypochlorite (NaOCl) is widely employed for sustaining MBR permeability, during which the inevitable contact between activated sludge and NaOCl had been shown to trigger substantial release of dissolved organic matter (DOM). Therefore, this work further explored the formation mechanisms of such DOM by looking into the respective reactions of intracellular organic matter (IOM) and cell debris in activated sludge with NaOCl. The results showed that DOM was primarily produced from the dissolution of cell wall, while IOM release was insignificant at the NaOCl concentration of 25 mg/L as Cl₂. On the basis of experimental observations, a three-step mechanism was proposed for elucidating the DOM formation from activated sludge upon NaOCl exposure: (i) NaOCl first damaged cells by perforating cellular wall, producing a considerable amount of humic-like substances and low-molecular-weight halogenated byproducts; (ii) IOM was released but rapidly degraded and humified by NaOCl, accompanied with the formation of relatively high-molecular-weight halogenated byproducts; (iii) the residual NaOCl and combined chlorine continued to react with cell wall or likely diffused into cells leading to the deactivation of DNA/enzymes. Consequently, this study offers mechanistic insights into the origination of emerging contaminants during on-line membrane cleaning of practical MBR.
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25651. 题目: Real-time monitoring the spatial distribution of organic fouling using fluorescence imaging technique
文章编号: N19122604
期刊: Journal of Membrane Science
作者: Sanghun Park, Suhan Kim, Jongkwan Park, Kyung Hwa Cho
更新时间: 2019-12-26
摘要: Many studies have demonstrated a close relationship between fouling and fluid dynamics to control fouling formation. However, few have been carried out to validate the relationship in practice, owing to the lack of techniques to evaluate fouling with hydrodynamics. We investigated the organic fouling of humic acid (HA) and tannic acid (TA) at three crossflow velocities using a fluorescence-labelled organism bioimaging instrument (FOBI). Higher crossflow velocity generally enhanced filtration performance; however, the type of foulants induced different fouling formation patterns on the membrane. The monitoring system and computational model revealed that HA fouling had strong (R² = 0.82) correlation with the shear rate (obtained from a velocity of 10.42 cm/s), while TA had weak correlation (R² = 0.13). HA fouling showed a high correlation with velocity profile at 10 cm/s, but TA fouling occurred in the over 20 cm/s velocity zone. This is because TA had relatively high adhesive force acting to the membrane, resulting in irreversible fouling that was hardly mitigated by crossflow control. Therefore, this study demonstrated that fouling development was predominantly controlled by hydrodynamic conditions, but the actual fouling distribution could be influenced by the physicochemical properties of dissolved organic matters.

25652. 题目: Vegetation change in the Baringo Basin, East Africa across the onset of Northern Hemisphere glaciation 3.3–2.6 Ma
文章编号: N19122603
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Rachel L. Lupien, James M. Russell, Chad L. Yost, John D. Kingston, Alan L. Deino, Jon Logan, Anna Schuh, Andrew S. Cohen
更新时间: 2019-12-26
摘要: Vegetation in East Africa is generally thought to have shifted from forests to more open grasslands and savannas as global climate cooled and high-latitude ice sheets expanded during the Plio-Pleistocene. Such a shift would have greatly influenced landscape resources, and potentially hominin evolution as well. Existing records of African vegetation spanning these time-scales are generally derived from offshore marine records that record continental-scale changes, or paleosol carbonate records that record very local vegetation changes during the short time intervals of soil carbonate formation. Here we present a new record of basin-scale vegetation change from the late Pliocene (~3.3–2.6 Ma) derived from a drill core from the Chemeron Formation, located in the Baringo Basin/Tugen Hills region of the Kenya Rift Valley. Specifically, we present a new record of the relative abundance of C₄ grasses and C₃ vegetation based on the carbon isotopic composition of leaf wax biomarkers (δ¹³C_wax), which captures a signal of regional vegetation change. These data demonstrate that vegetation in the Baringo Basin varied greatly between C₃ forests and C₄ grasslands, and that vegetation exhibits both long-term (secular) trends and orbital-scale variations. The contribution of C₃ plants was lower than estimates based on low-resolution carbon isotope data from paleosol carbonates and organic matter in the basin. C₃ plants averaged ~53% of the vegetation during the late Pliocene, from ~3.3 to ~3.04 Ma, after which time δ¹³C_wax indicates more open vegetation and ~41% C₃ plants. This transition may have been driven by changes in basin geomorphology, but also possibly occurred as part of larger-scale drying and expansion of C₄ vegetation in East Africa. In addition to this secular change, we observe high amplitude variability in the δ¹³C_wax record including oscillations between ~80 and ~0% C₃ plants. These vegetation changes are correlated with changes in precipitation inferred from δ²H_wax and lake level oscillations inferred from sedimentary facies, implying that high-amplitude, orbital-scale variations in precipitation drove significant changes in vegetation resources during the late Pliocene in the Baringo Basin. These variations have important implications for changes in terrestrial resources in light of the evolutionary innovations in the hominin fossil record related to changes in foraging strategies.

25653. 题目: Concomitant use of Azolla derived bioelectrode as anode and hydrolysate as substrate for microbial fuel cell and electro-fermentation applications
文章编号: N19122602
期刊: Science of The Total Environment
作者: Manupati Hemalatha, J. Shanthi Sravan, Booki Min, S. Venkata Mohan
更新时间: 2019-12-26
摘要: The potential of deoiled Azolla pinnata biomass (DAB) as electrode and substrate was evaluated for microbial fuel cell (MFC) operation. The anode electrode was fabricated using biochar obtained by subjecting DAB to pyrolysis at 600 °C, while the reducing sugars after hydrolysis of DAB by acid pretreatment was used as substrate. The post pyrolyzed biochar (P-DAB) was characterized for structural and elemental functionalities using SEM, XRD and Raman spectroscopy, whereas the reducing sugar obtained from hydrolyzed DAB (H-DAB) was analyzed for its composition. Experimental results indicated that at a given 3 g COD/L resulted in a voltage of 382 mV with 65.6% of COD reduction in closed circuit (CC) mode of operation. Cyclic voltammetric analysis depicted maximum oxidative and reductive peak currents of 3.42 mA and −4.0 mA. Noticeable peaks were also identified in CC (−0.2 V to +0.2 V and −0.19 V to −0.3 V) and OC (+0.2 V to +0.4 V and −0.1 V to −0.3 V) corresponding to complex IV cytochrome c couples (cytochrome C_ox (Cyt C_ox)/cytochrome C_rd (Cyt C_rd)), signifying the participation of electron carriers during electron transfer. The microbiome diversity showed dominance of Proteobacteria, a phylum known for exo-electrogenic bacterial species. The DAB-derived products account to environmental sustainability and support circular bioeconomy in a biorefinery mode.
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25654. 题目: Biochar-induced reductions in the rhizosphere priming effect are weaker under elevated CO₂
文章编号: N19122601
期刊: Soil Biology and Biochemistry
作者: Junmin Pei, Feike A. Dijkstra, Jinquan Li, Changming Fang, Jinghua Su, Jiayuan Zhao, Ming Nie, Jihua Wu
更新时间: 2019-12-26
摘要: Biochar can store carbon in soils for decades to centuries, and is considered to have some potential to contribute to mitigating climate change. However, both biochar and elevated atmospheric CO₂ (eCO₂) can influence the rhizosphere priming effect (RPE) on pre-existing soil organic carbon (SOC) decomposition, leading to uncertainty in comprehensively evaluating the soil carbon sequestration potential of biochar under future climate change. In the present study, we investigated the RPE on pre-existing SOC decomposition of paddy rice in a soil-plant-biochar system under eCO₂ (700 ppm). Plant-derived sources of carbon were separated from soil-derived sources using a continuous ¹³C-labelling method. We found that the RPEs decreased significantly with increasing biochar addition rates (1%, 2%, 3%, 4%, and 5% by weight) with mean reductions of 12% and 40% on 31 and 54 days after sowing, respectively, suggesting that biochar can enhance the stability of pre-existing SOC by decreasing the RPE. Although compared to ambient CO₂ (aCO₂, 400 ppm), eCO₂ significantly decreased RPEs by 33% and 37% on 31 and 54 days after sowing, respectively, the decline in the RPE in response to biochar was weaker under eCO₂. Decreases in soil enzyme activities and microbial biomass carbon could explain the decline in the RPE in response to biochar addition. Our findings highlight that biochar can inhibit the decomposition of pre-existing SOC by reducing the RPE, while this effect will be weakened in the face of atmospheric CO₂ increase in the future.
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25655. 题目: Soil organic carbon increment sources and crop yields under long‐term conservation tillage practices in wheat‐maize systems
文章编号: N19122525
期刊: Land Degradation & Development
作者: Zhen Liu, Tian‐Ping Gao, Shen‐Zhong Tian, Heng‐Yu Hu, Geng Li, Tangyuan Ning
更新时间: 2019-12-25
摘要: Long‐term tillage and straw incorporation significantly affect soil organic carbon (SOC) sequestration and crop yield. However, the studies on the SOC sources under multi‐cropping system are relatively few. The objective of this study was to evaluate the effects of conservation tillage on SOC and crop yields, and distinguish the SOC sources from wheat (C3) and maize (C4). Therefore, the dynamics of SOC, SOC sequestration and crop yield were evaluated during 15 years of conservation agriculture under conventional tillage (CT), subsoiling (ST), rotary tillage (RT), and no‐tillage (NT) without or with straw incorporation (CTS, STS, RTS, and NTS, respectively). The results indicated that the highest mean SOC concentration in the 0–30 cm soil was found under STS (11.80 g/kg), which increased by 2.29 g/kg than that under CT, while RT had the lowest mean SOC concentration (8.10 g/kg). The increases in annual yield ranged from 0.58 (NT) to 4.93 (ST) Mg/ha during 2005–2017. In comparison to the annual yield of CT, that of STS increased by 2 Mg/ha and was significantly higher than other treatments (p < 0.05) except NTS and CTS. In comparison to CT, the SOC stock (SOCs) and carbon sequestration rate (CSR) of STS were the highest and increased by 15.64 Mg/ha and 1.05 Mg/ha/yr, respectively, in the 0–30 cm soil. Moreover, the relative contribution of wheat residues to SOC was higher than maize residues under all treatments. Thus, subsoiling combined with C3 straw incorporation was more suitable for restoring degraded land and increasing yields.

25656. 题目: A Novel Magnetic Biochar Prepared by K₂FeO₄-Promoted Oxidative Pyrolysis of Pomelo Peel for Adsorption of Hexavalent Chromium
文章编号: N19122524
期刊: Bioresource Technology
作者: Zhibing Yin, Shuang Xu, Sen Liu, Shuying Xu, Jihui Li, Yucang Zhang
更新时间: 2019-12-25
摘要: Magnetic biochar was usually prepared using ferrous and ferric compounds as precursor of magnetic medium. Ferrate, which could be an internal oxidative modifier, was less explored for preparing magnetic biochar. Here, a magnetic biochar was prepared through K₂FeO₄-promoted pyrolysis of pomelo peel for adsorption of hexavalent chromium. Oxygen-containing groups and single phase ɤ-Fe₂O₃ were simultaneously introduced into biochar matrix at 300 ^oC. The magnetic biochar exhibited 209.64 mg/g maximum adsorption capability at 45 ^oC, outperformed the best magnetic biochar with 142.86 mg/g maximum adsorption capability at 40 ^oC in the literature. Moreover, a good magnetism was obtained, facilitating separation of the magnetic biochar from aqueous solution by a magnet. The removal of hexavalent chromium was contributed to the hybrid adsorption of ɤ-Fe₂O₃ and biochar matrix by reduction, electrostatic interaction and complexation. This method was attractive, required neither extra modifiers nor multiple operations for preparation of highly adsorptive magnetic biochar.
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25657. 题目: Novel external extractive membrane bioreactor (EMBR) using electrospun polydimethylsiloxane/polymethyl methacrylate membrane for phenol-laden saline wastewater
文章编号: N19122523
期刊: Chemical Engineering Journal
作者: Long-Fei Ren, Huu Hao Ngo, Cuina Bu, Chenghao Ge, Shou-Qing Ni, Jiahui Shao, Yiliang He
更新时间: 2019-12-25
摘要: Phenol-laden saline wastewaters can adversely affect water, groundwater, soil, organisms and ecosystems. Given that frequently-used biodegradation process is generally inhibited by salinity, this work aims to solve the problem through a novel configuration of external extractive membrane bioreactor (EMBR) for the objective of simultaneous phenol permeation, salt rejection and biodegradation. Contact angles of 160.9 ± 2.2° (water) and 0.0° (phenol) were observed on the electrospun polydimethylsiloxane/polymethyl methacrylate (PDMS/PMMA) membrane, suggesting this superhydrophobic/superorganophilic membrane was suitable for separating phenol from water-soluble salt. Phenol ranging from 14.1 ± 2.7 to 290.7 ± 10.4 mg/L (stages 1 to 8) was continuously permeated and completely biodegraded in external EMBR under a hydraulic retention time (HRT) of 24 h, which corresponded with detoxification performance improving from 6.3% to 70.5%. After phenol exposure of 8 stages, Proteobacteria and Saccharibacteria became the main phyla for microorganisms. Enumeration of functional genes (phe, amoA, narG, nirS) confirmed that phenol was mainly consumed by denitrifiers and other heterotrophs as the sole carbon and energy source via oxidation and ring cleavage. As bacterial responses, these genes’ proliferation was promoted under low phenol concentrations but inhibited under high phenol concentrations. Meanwhile, results of extracellular polymeric substances revealed that protein was the key substance in toxicity resistance, phenol adsorption and transfer.

25658. 题目: Role of GAC-MnO₂ catalyst for triggering the extracellular electron transfer and boosting CH₄ production in syntrophic methanogenesis
文章编号: N19122522
期刊: Chemical Engineering Journal
作者: Bo Yang, Hui Xu, Yanbiao Liu, Fang Li, Xinshan Song, Zhiwei Wang, Wolfgang Sand
更新时间: 2019-12-25
摘要: The addition of conductive materials or metal oxide nanoparticles (NPs) to anaerobic systems is an attractive strategy to enhance the anaerobic digestion and the production of CH₄. This study proposed a strategy to boost the CH₄ production by adding granular activated carbon (GAC)-MnO₂ nanocomposites into an anaerobic methanogenic system. The associated mechanisms and the microbial community structure during anaerobic digestion were investigated systematically. Compared with a control with GAC only, after adding GAC-MnO₂ composite the chemical oxygen demand (COD) removal efficiency and CH₄ yield were increased by 77% and 36%, respectively. The addition of GAC-MnO₂ stimulated the secretion of extracellular polymeric substance (EPS), while the secretion of humic substances was inhibited. The spatial distribution of EPS in the anaerobic sludge affects the extracellular electron transfer efficiency as well. Manganese ions concentrated in the EPS layer facilitated the electron flow and, thus, accelerated the extracellular electron transfer. The enhancement of anaerobic methanogenesis can be mainly attributed to the reduction/oxidation cycle of Mn⁴⁺/Mn²⁺. Electron transfer system activity and Cytochrome C content reached up to 341 and 38 nmol/L, respectively, under optimal conditions. 16S rRNA gene sequencing analysis indicated that Spirochaetaceae, Cloacibacterium, and Treponema were the dominant bacteria. The abundance of the methanogenic archaea Methanobacterium and Methanosaeta were increased with the addition of GAC-MnO₂.
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25659. 题目: Effects of humic acid and fulvic acid on the sequestration of copper and carbon during the iron oxide transformation
文章编号: N19122521
期刊: Chemical Engineering Journal
作者: Yang Lu, Shiwen Hu, Fu Liu, Yuzhen Liang, Zhenqing Shi
更新时间: 2019-12-25
摘要: In natural environments, the iron oxide transformation is associated with natural organic matter (NOM) and heavy metals. However, there is still a lack of knowledge on the dynamic interactions among NOM, iron oxides, and heavy metals during the iron oxide transformation process, which has significant implications on the fate of metals and carbon (C) in the environment. In this study, two types of NOM, fulvic acid and humic acid (FA and HA) were used to elucidate the influence of NOM on the iron oxide transformation and the dynamic distribution and speciation of Cu and C during the iron oxide transformation. The X-ray diffraction (XRD) and extended X-ray absorption fine structure (EXAFS) spectroscopy showed that both FA and HA decreased the rates of ferrihydrite transformation to hematite. The EXAFS analysis of Cu speciation and spherical aberration corrected scanning transmission electron microscope (Cs-STEM) showed that Cu could be incorporated into the hematite particles while HA and FA hindered the incorporation of Cu, consistent with the chemical extraction results. Compared with FA, HA resulted in more extractable Cu by diluted acid and less Cu incorporation into iron oxides. The Cs-STEM results showed that both HA and FA resulted in the formation of ellipsoidal hematite particles with a loose structure. Batch extraction experiments and the Cs-STEM imaging, collectively, indicated that HA might penetrate into the loose and porous structure of hematite nanoparticles, which was less evident for FA. Results in this study help to understand the environmental behaviors of C and Cu during the iron oxide transformation process and also shed light on the nanoscale mechanisms of C sequestration within iron oxides.
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25660. 题目: Mechanisms for cadmium adsorption by magnetic biochar composites in an aqueous solution
文章编号: N19122520
期刊: Chemosphere
作者: Zulqarnain Haider Khan, Minling Gao, Weiwen Qiu, Md. Shafiqul Islam, Zhengguo Song
更新时间: 2019-12-25
摘要: There is a demand to develop techniques for the continuous removal/immobilization of heavy metals from contaminated soil and water bodies. In this study, a unique biochar preparation method was developed for the removal of cadmium. First, conventional biochars of corn straw were produced by pyrolysis at two temperatures and then treated using one-step synthesis at different ferric nitrate ratios and different calcination temperatures to produce magnetic biochars. Second, the prepared biochars were used as adsorbents for Cd(II) removal from a solution, and the best one was selected for further evaluation. Various techniques were used to characterize the adsorbents and determine the main adsorption mechanism. The results indicated that the biochars successfully carried iron particles within, which improved the specific surface area, formed inner-sphere complexes with oxygen-containing groups, and increased the number of oxygen-containing groups. The adsorption experiments revealed that MBC800-0.6₃₀₀ had a higher affinity for Cd(II) than the other adsorbents. Batch adsorption experiments were performed to explore the influence of the kinetics, isotherm, pH, thermodynamics, ionic strength, and humic acid on Cd(II) adsorption. The results indicated that the Langmuir model fit the Cd(II) adsorption best with MBC800-0.6₃₀₀ having the highest adsorption capacity (46.90 mg g⁻¹). The sorption kinetics of Cd(II) on the adsorbent follows a pseudo-second-order kinetics model. Because MBC800-0.6₃₀₀ is loaded with metal ions, it can be conveniently collected by a magnet. Thus, biochar modification methods with ferric nitrate impregnation provide an excellent approach to eliminating Cd(II) from aqueous solutions. The possible adsorption mechanisms include chemisorption, electrostatic interaction, and monolayer adsorption.