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24401. 题目: Biochar as a catalytic material for the production of 1,4-butanediol and tetrahydrofuran from furan
文章编号: N20030601
期刊: Environmental Research
作者: Younghyun Lee, Yong Tae Kim, Eilhann E. Kwon, Jechan Lee
更新时间: 2020-03-06
摘要: Biomass valorization is emerging as a new trend for the synthesis of materials for various environmental applications. In this connection, a biochar resulting from pyrolysis of rice straw was employed as a catalytic material for the conversion of hemicellulose-derived furan into value-added platform chemicals such as 1,4-butanediol (1,4-BD) and tetrahydrofuran (THF). The biochar was used as catalyst support of bifunctional Ru–Re catalyst. Two different catalysts were prepared: a conventional activated carbon (AC)-supported Ru–Re catalyst (Ru–Re/AC) and a biochar-supported Ru–Re catalyst (Ru–Re/biochar). The Ru–Re/biochar had a different form of Re species from the Ru–Re/AC, resulting in different reducibility. The difference of reducibility between the two was attributed to alkali metal present in the biochar such as potassium. The Ru–Re/biochar had a 17 times lower metal dispersion on the surface than the Ru–Re/AC, ascribed to a lower surface area of the biochar than the AC. Catalytic activities of the catalysts with regard to reaction rate per available surface active site for transforming furan to 1,4-BD and THF were measured. The Ru–Re/AC was 3 times less active than the Ru–Re/biochar. This study not only provides a way to efficiently use biomass both for environmental catalysts and for feedstock of producing value-added platform chemicals, but also shows potential of biochar for the replacement of typical catalysts employed in biorefinery.

24402. 题目: Online measurements of very low elemental and organic carbon concentrations in aerosols at a subarctic remote station
文章编号: N20030518
期刊: Atmospheric Environment
作者: Petr Vodička, Jaroslav Schwarz, David Brus, Vladimír Ždímal
更新时间: 2020-03-05
摘要: Two months (Oct.–Nov. 2015) of online elemental carbon (EC) and organic carbon (OC) measurements were performed by two field OC/EC Sunset Laboratory analysers working in parallel with an 8-h time resolution at a subarctic remote station in Finland. During such a time resolution, thermal OC and EC concentrations were usually close to or below the recent limits of detection for the analyser. Thus, this work highlights the possible issues to consider during the online measurements of OC/EC analysers working at the threshold of their analytical possibilities. A detailed analysis of the data showed that even though the OC concentrations were always above the detection limit of the analyser, up to 70% of the given concentration was due to the dynamic blank (gaseous phase). The majority of the OC aerosol was present in the less volatile fractions that evolved during steps at 300–450 °C and 450–650 °C. The main bias at low EC concentrations originated from the automatically determined split point between OC and EC. The results from the RTCalc526 software often led to an early determination of the OC-EC split point, resulting in an overestimation of the EC concentrations. However, the comparison of the results was performed after processing the OC/EC raw data in the different RTCalc software versions 526 and 703. The results showed that the EC values from the newer version of the RTCalc703 software were more consistent with the equivalent black carbon (eBC) results from optical instruments (aethalometer and MAAP) measured in parallel in comparison with results from the older RTCalc526 software. Equivalent BC data from the laser attenuation measurement of the Sunset Lab. analyser also provided better agreement with the newer version of the RTCalc software (RTCalc703).

24403. 题目: Global Model for Depth‐Dependent Carbonyl Photochemical Production Rates in Seawater
文章编号: N20030517
期刊: Global Biogeochemical Cycles
作者: Yuting Zhu, David J. Kieber
更新时间: 2020-03-05
摘要: A photochemical model was used to quantify the global relative contribution of carbonyl photoproduction in the photodegradation of marine dissolved organic carbon (DOC). As model input, wavelength‐ and temperature‐dependent apparent quantum yields (AQY) for the photochemical production of carbonyl compounds were determined in seawater collected from the Northwest Atlantic Ocean. These AQY data and published AQY data from the North Pacific were used with remotely sensed seawater optical properties and solar irradiance data in a global model to calculate depth‐resolved, mixed‐layer photochemical fluxes of acetaldehyde and glyoxal in seawater. Based on this model, the annual global surface mixed‐layer photochemical production is 119±36 Tg y‐1 for acetaldehyde and 19.8±5.9 Tg y‐1 for glyoxal. This work significantly improves our understanding of the impact of photochemistry on the cycling of DOC in the surface oceans. Low‐molecular‐weight carbonyl compounds represent the second largest carbon flux among all known carbon products that are produced during the photolysis of DOC. The annual photoproduction of carbonyl‐compound carbon is ~142±23 Tg C y‐1, comprising approximately 12% of the total carbon and 28% of the biologically labile carbon that are produced globally from the photolysis of marine DOC.

24404. 题目: Distribution pattern of antibiotic resistance genes and bacterial community in agricultural soil samples of Wuliangsuhai watershed. China
文章编号: N20030516
期刊: Agriculture, Ecosystems & Environment
作者: Wei Shi, Yong Liu, Junjian Li, Hong Zhang, Rui Shi, Jianwen Chen, Hongjian Li
更新时间: 2020-03-05
摘要: The occurrence and dissemination of antibiotic resistance genes (ARGs) constitute a major concern worldwide, and pose crucial threats to public health. The current study focused on this issue in the agricultural soils of Wuliangsuhai watershed in China. A total of 33 ARGs, belonging to 8 major types, were identified in the soil samples, mexF, blaTEM, vanD, sulI, sulII, and oprJ being the predominant ones. The abundance of ARGs ranged from 2.18 × 10−6–1.9 × 10-2 copies/16S rRNA gene copies. Results of correlation analyses confirmed that intI1 significantly correlated with ARGs (aadA1, aadA2, mphA, sulI, and sulII), indicating the potential horizontal transfer capability of these genes in soil. Based on the proximity of different sampling sites with urban areas, we found the abundance of bacterial community and ARGs to significantly increase in the sites proximal to urban area, which indicated the agricultural activities and industrial pollution might alter the bacterial community structure and spatial distribution of ARGs. In addition, the correlation between ARGs and environmental factors confirmed the association of microbial community distribution with environmental factors, such as soil organic matter (SOM), available phosphorus (AP), and total nitrogen (TN). The co-occurrence pattern of ARGs and bacterial taxa indicated the succession of Firmicutes and Proteobacteria to possibly be the potential driver for variation in ARGs in the different sampling sites examined. These findings are expected to improve the current understanding of ARG distribution and their relationship with microbial community succession.

24405. 题目: Photochemical behaviors of mercury (Hg) species in aquatic systems: A systematic review on reaction process, mechanism, and influencing factor
文章编号: N20030515
期刊: Science of The Total Environment
作者: Hongwei Luo, Qianqian Cheng, Xiangliang Pan
更新时间: 2020-03-05
摘要: The fate and transport of Hg species in natural aquatic environment are strongly affected by photochemical transformation of Hg0, Hg2+, and MeHg. Migration of Hg is determined by its complexation with organic and inorganic ligands that are widely present in the water. The presence of dissolved organic matter (DOM) is closely related to photochemical reactions of Hg. DOM can strongly bind to mercury (e.g., Hg2+ and MeHg), thus affecting its speciation, mobility and toxicity, eventually dominating its bioavailability. This review summarizes extensive studies on photochemical behaviors of Hg including: (1) photo-oxidation; (2) photo-reduction; (3) photochemical methylation; and (4) MeHg photo-degradation. Photo-oxidation of Hg0 is mostly caused by oxidative free radicals (e.g., •OH, CO3•−, O3, and 1O2), while photo-reduction of Hg2+ is more complicated and it involves two pathways: (1) primary processes (direct photolysis of Hg2+ or ligand-metal charge transfer of Hg2+-DOM complex); and (2) secondary processes (reduction of Hg2+-DOM complex induced by free radicals derived from DOM photolysis). Photochemical methylation of inorganic Hg occurs as follows: (1) Hg2+ complexes with methyl donors (e.g., acetic acid, tert-butyl, alcohols, etc.) to form intermediates, followed by (2) an intramolecular methyl transfer. MeHg photo-degradation is the leading pathway for MeHg demethylation and it primarily proceeds via four different pathways. The information on DOM was also mentioned, but DOM is not the only factor that affects the photochemical behaviors of Hg. Other influencing factors such as: (1) pH value; (2) dissolved oxygen; (3) cations (Fe3+, K+) and anions (NO3−, HCO3−, CO32−, Cl−); and (4) suspended substance cannot be ignored.

24406. 题目: Insights into solubility of soil humic substances and their fluorescence characterisation in three characteristic soils
文章编号: N20030514
期刊: Science of The Total Environment
作者: M. Mohinuzzaman, Jie Yuan, Xuemei Yang, Nicola Senesi, Si-Liang Li, Rob M. Ellam, Khan M.G. Mostofa, Cong-Qiang Liu
更新时间: 2020-03-05
摘要: Soil humic substances (HS) are involved in almost all biogeochemical processes and functions in soils, thus their extraction from aiming to their characterization is very important. However, many factors that influence HS extraction from soil still need further studies. The aim of this work was to assess and quantify comparatively the solubility of soil HS as a function of extraction time, various extractants, solid to liquid ratio and sequential extraction. In this work three different soils, i.e. a forest, a maize and a paddy soil, were examined to assess the solubility of soil HS based on their fluorescence (excitation-emission matrix, EEM) features and changes in nutrient (NO3−-N, PO43−-P and dissolved Si) contents using multiple extraction approaches (time-dependent, various extractants, solid to liquid ratio, and sequential extraction). Three fluorescent components, i.e. humic acids-like (HA-like), fulvic acids-like (FA-like), and protein-like fluorophores (PLF), were identified by parallel factor (PARAFAC) analysis of EEM spectra of the various soil extracts. The solubility of HS, dissolved organic carbon (DOC) and nutrients were shown to increase with extraction time, except for PLF. The FA-like fraction disappeared completely in KCl extracts of all three soils, suggesting the inefficiency of salt extraction. Conversely, HS and nutrients solubility substantially increased in alkaline extracts, and dissolved Si was correlated significantly with the fluorescent intensities of HA-like and FA-like, thus confirming the well-known typical process of alkaline dissolution of HS bound to phytolith and silicate minerals. The relative solubility of HS and nutrients was higher at lower solid to liquid ratio (1:250–1:100), whereas their maximum yields was achieved at high solid to liquid ratio (1:10) for all three soils. Sequential extraction results showed that the first water extraction step contributed 42–55% of HS, which suggested that a single extraction was insufficient to recover HS. In conclusion, water and alkaline extraction could provide, respectively, the labile and insoluble complexed HS existing in soil.

24407. 题目: The sensitivity of the carbon sink by coupled carbonate weathering to climate and land-use changes: Sediment records of the biological carbon pump effect in Fuxian Lake, Yunnan, China, during the past century
文章编号: N20030513
期刊: Science of The Total Environment
作者: Haibo He, Zaihua Liu, Chongying Chen, Yu Wei, Qian Bao, Hailong Sun, Hao Yan
更新时间: 2020-03-05
摘要: Recent studies show that the carbon sink attributable to the weathering of carbonate rocks may have been greatly underestimated if the biological carbon pump (BCP) effect in transferring dissolved inorganic carbon (DIC) to organic carbon (autochthonous OC) by aquatic photoautotrophs is neglected. The uptake of DIC by aquatic photoautotrophs may reach 0.2 to 0.7 Pg C/a globally, indicating that the carbon sink by the coupled carbonate weathering with aquatic photosynthesis mechanism (CCW) may be an important control in climate change. In order to understand the sensitivity of the CCW carbon sink to changes of climate and land-use, a systematic study of modern trap and 100-year-long core sediments was conducted in Fuxian Lake, (Yunnan, SW China), the second-deepest plateau oligotrophic freshwater lake in China. It was found that (1) the autochthonous OC in the lake sediments was characterized by lower C/N ratios and higher δ13Corg. By means of an n-alkanes compound calculation, the proportions of autochthonous OC were determined to be in the range, 60–68% of all OC; (2) increase in the autochthonous OC accumulation rate (OCARauto) was accompanied by an increase in the inorganic carbon accumulation rate (ICAR) in both the trap and core sediments. In particular, the post-1950 OCARauto was estimated to be about 6.9 times that for the period, 1910–1950; (3) OCARauto in core sediments increased significantly with global warming and land-use change, from 1.06 g C m−2 yr−1 in 1910 to 21.74 g C m−2 yr−1 in 2017. The increasing carbon sink may act as a negative feedback on global warming if the trend holds for all lakes globally. This study is the first to quantify the burial flux of organic carbon generated by the BCP effect in lakes and may contribute to solving the problem of the missing carbon sink in the global carbon cycle.

24408. 题目: Green immobilization of toxic metals using alkaline enhanced rice husk biochar: Effects of pyrolysis temperature and KOH concentration
文章编号: N20030512
期刊: Science of The Total Environment
作者: Liuwei Wang, Nanthi S. Bolan, Daniel C.W. Tsang, Deyi Hou
更新时间: 2020-03-05
摘要: Biochar is a green material that has been widely used in environmental applications for its capability to remove or immobilize contaminants in different environmental media (i.e. soil, water and air) and mitigate climate change. In this study, the feasibility of using KOH enhanced biochar for soil Cd and Pb stabilization was investigated, and the effects of pyrolysis temperature and alkaline concentrations for modification were explored. Field-emission scanning electron microscopy (FESEM), N2 adsorption-desorption, and Fourier Transform Infrared Spectroscopy (FTIR) analyses were conducted to reveal the influence on biochar physiochemical properties. The immobilization performances were examined through Toxicity Characteristics Leaching Procedure (TCLP), and Response Surface Methodology (RSM) was adopted to visualize the results from leaching tests. The stabilization mechanisms of alkaline enhanced biochars were investigated using Time of Flight Secondary Ion Mass Spectroscopy (TOF-SIMS), Tessier sequential extraction method and X-ray diffraction (XRD) analyses. The results indicated that rice husk biochar pyrolyzed at a relatively low temperature (i.e., 300 °C) and activated by moderate alkaline concentrations (i.e., 1 M or 3 M KOH) rendered optimum stabilization performance. KOH activation was a double-edged sword, with high alkaline concentrations destroying biochar's cell structures. Moreover, the integration of TOF-SIMS, XRD and sequential leaching method shed lights on the underlying mechanisms involved in metal stabilization. Surface complexation between toxic metals and oxygen-containing functional groups rather than liming or precipitation was proven to be the fundamental stabilization mechanism.

24409. 题目: The influence of extracellular polymeric substances on the coagulation process of cyanobacteria
文章编号: N20030511
期刊: Science of The Total Environment
作者: Feng Sun, Hanyuan Zhang, Aijuan Qian, Hongfei Yu, Chenhui Xu, Rong Pan, Yijing Shi
更新时间: 2020-03-05
摘要: The hydrophobicity and flocculation properties of cyanobacterial cells are closely related to their extracellular polymeric substances (EPS). During the treatment of drinking water, the coagulation and removal of EPS-wrapped cyanobacterial particles from natural water sources is very difficult. In this work, a series of surface characteristics of cyanobacterial cells with different EPS fractions were analyzed to evaluate their influences on the coagulation process. With the removal of EPS, the coagulation efficiency of cyanobacteria was gradually improved. The intracellular microcystin release showed that the cyanobacterial cells in each EPS removal phase were almost intact with few broken cells. The surface of cyanobacterial cells had higher hydrophobicity and lower zeta potentials with each step of the EPS extraction, which improved the ratio of particles that were in an unstable state. Furthermore, the deeper the EPS extraction phase, the larger the decreased in size of cyanobacterial particles, thus increasing their specific surface area for adsorption with coagulant. It was concluded that the coagulation mechanism of EPS-wrapped cyanobacterial particles was: the cyanobacterial cells were first peeled off through attraction by opposite charges from the coagulant, and then they were adsorbed before settling down. This study provides a scientific basis for the removal of cyanobacteria by enhancing coagulation.

24410. 题目: Influence of sodium hydroxide addition on characteristics and environmental risk of heavy metals in biochars derived from swine manure
文章编号: N20030510
期刊: Waste Management
作者: Yonggang Xu, Tianxia Bai, Yubo Yan, Kuirong Ma
更新时间: 2020-03-05
摘要: In order to improve characteristics of biochar, especially enhance immobilization of heavy metals in biochar, swine manure was pyrolyzed at low pyrolysis temperature (300 °C, 400 °C and 500 °C) with different amounts of sodium hydroxide (NaOH) added (0.5% and 2%, W/W). Results showed that NaOH addition during pyrolysis increased the pH, EC, ash content, yield rate, aromaticity and hydrophily, but did not increase surface area and porosity of resultant biochars. The addition of NaOH promoted the transformation of the mobile fraction of Cu, Zn and Cd into the oxidizable fraction. With respect to Cr and Pb, the oxidizable and residual fractions were increased slightly by the presence of NaOH. Meanwhile, adding NaOH could reduce the leachability and ecological risks of heavy metals in biochars. Our study suggested that NaOH-assisted pyrolysis of swine manure was an effective disposal approach for the immobilization of heavy metals.

24411. 题目: Continuity of biochar-associated biofilm in anaerobic digestion
文章编号: N20030509
期刊: Chemical Engineering Journal
作者: Pinjing He, Haohao Zhang, Haowen Duan, Liming Shao, Fan Lü
更新时间: 2020-03-05
摘要: Several single dose studies found that biochar was an effective additive promoting methanogenesis in anaerobic digestion. However, little attention was paid to the continuity of the biofilm formed on biochar and the subsequent evolution of microorganisms. In this study, the continuous performance and changes were quantified when biochar-biofilm consortia were applied as the recyclable inoculant to four cycles of acetate methanogenesis with increasing acetate loading. Biochar-biofilm consortia as the inoculant were found to consistently realize stable methane production, despite the removal of planktonic microorganisms in the reactor, and no extra inoculum and biochar were added. Consortia with biochar particles smaller than 5 μm promoted initiation of methanogenesis more rapidly than those with biochar particles larger than 1 mm, especially when the activity of microorganism was low. Moreover, the microorganisms were enriched throughout the continuous cycles. Biochar < 5 μm was found to accumulate 6.6–7.1 E + 11 16S copies per gram in the 3rd and 4th cycles, which was about 27–51 times that of biochar > 1 mm and also comparable to a fresh sludge inoculum. In addition, specific functional methanogens proliferated during continuous application. Methanosarcina was dominant in biochar > 1 mm, while the syntrophic acetate oxidizing bacteria Thermovirga and Mesotoga accounted for the majority of microorganisms in biochar < 5 μm. Therefore, with the competitive total cell count dominated by functional microorganisms, biochar-biofilm consortia demonstrated feasible recycling and reuse for bioaugmentation purposes or in the economical long-term application of anaerobic digestion for waste or wastewater treatment.

24412. 题目: Long-term effect of rice-based cropping systems on pools of soil organic carbon in farmer’s field in hilly agroecosystem of Manipur, India
文章编号: N20030508
期刊: Environmental Monitoring and Assessment
作者: Thounaojam Thomas Meetei, Manik Chandra Kundu, Yumnam Bijilaxmi Devi
更新时间: 2020-03-05
摘要: A comprehensive study on various pools of soil organic carbon (SOC) under different rice-based cropping systems is necessary for predicting their effect on soil quality through carbon build-up in soil and their impact on global climate change. The present investigation was undertaken to study the long-term effect of six different rice-based cropping systems (continuously followed by farmers > 10 years) on various SOC pools viz., total organic carbon (TOC), oxidizable organic carbon (Coc) and its different fractions [Cfrac1 (very labile), Cfrac2 (labile), Cfrac3 (less labile) and Cfrac4 (non-labile)], soil microbial biomass carbon (SMBC) and lability index (LI) and SOC stock at the farmer's field of Kakching district under hilly ecosystems of Manipur, India. In every cropping system, all the fractions of Coc were significantly decreased with increasing soil depth. Among all the fractions, Cfrac4 (non-labile) constituted the largest percentage of TOC for both surface (0-20 cm) and sub-surface (20-40 cm) soil varying from 47.95–58.45% and 55.76–64.83% with average values of 51.87 and 59.73% respectively. Results also revealed that the Cfrac1 (very labile) of Coc constituted highest (42.79%) percentage of Coc and that of Cfract4 constituted highest percentage (55.80%) of TOC. In both soil depths, rice-pea cropping system recorded highest TOC, Coc and SMBC followed by rice-French bean and rice-potato. In surface soil, the lowest TOC, Coc and SMBC were recorded in rice-mustard which was statistically at par with rice-cabbage. The SOC stock of both soil layers was also recorded highest in rice-pea. The highest LI of surface soil was recorded in rice-potato which was statistically equal with rice-pea and rice-French bean. Significant correlations among different pools/fractions of C and with available nutrients indicate their importance in improving soil quality. Long-term combination of rice with the leguminous crops and/or potato enhanced Coc, TOC, SMBC, LI and active pools (Cfrac1 + Cfrac2) of rapid turnover rate that may influence the quality and productivity of soil. Long-term cultivation of rice-French bean with high passive C along with good active C and LI is proved to be a good cropping system for sustaining soil and environment by enhancing quality and C reserve of degraded soils of hilly agroecosystem.

24413. 题目: Potential of tea plants in carbon sequestration in North-East India
文章编号: N20030507
期刊: Environmental Monitoring and Assessment
作者: Prabhat Pramanik, Manabjyoti Phukan
更新时间: 2020-03-05
摘要: The potential of carbon (C) sequestration through photosynthesis depends on the nature of different plant species. Tea (Camellia sinensis L.) is an evergreen perennial plant and cultivated over a wide region in the world, and its potential to sequestrate atmospheric carbon dioxide (CO2) in plant biomass is already evaluated. However, proportions of assimilated CO2 which tea plant can sequestrate in their biomass and in soil are not evaluated before. In this experiment, ten (10) 6-month old tea plants of four different cultivars (TV1, TV20, S3A/3, and TV23) were transplanted in the field and CO2 assimilation flux of tea plants was periodically measured under in situ condition using close-chamber method at 15 days interval throughout the year. The cumulative CO2 assimilation flux of young tea plants varied within 31.82–249.22 g CO2 plant−1 year−1; however, it was estimated that tea bushes also emitted 5.2–70.8 g CO2 plant−1 year−1 due to aerobic respiration. After 1 year, tea plants were uprooted and the changes in their biomass were compared as the measure of their C-sequestration within the study duration. The weight gain in the whole plant biomass was proportional to the CO2 assimilation potential of tea cultivars. Overall, tea plants sequestrated 50.8% of the assimilated atmospheric CO2 in their biomass. The study revealed that tea bushes release organic C through the root exudates, the amount of which was equivalent to 5.9–8.6% of the assimilated CO2. Those secreted root exudates have potential to increase organic C up to 44–48 kg ha−1 year−1 in tea-growing soil.

24414. 题目: Polycyclic aromatic hydrocarbons in surface sediments of the Aegean Sea (eastern Mediterranean Sea)
文章编号: N20030506
期刊: Marine Pollution Bulletin
作者: I. Hatzianestis, C. Parinos, I. Bouloubassi, A. Gogou
更新时间: 2020-03-05
摘要: In this study, we provide baseline data on the composition, major sources and mechanisms driving the distribution of polycyclic aromatic hydrocarbons (PAHs) mixtures in surficial sediments collected from 43 offshore and open/deep sea locations across the north, central and south Aegean Sea. The determined total concentrations of the considered PAH compounds were generally low, comparable to those reported in relatively non-polluted coastal and open/deep Mediterranean marine sites. Their molecular profile and diagnostic indices reveal mixed contributions from both pyrolytic and petrogenic sources across the study area. Organic carbon exerts an important control on the transport and ultimate accumulation of PAHs, however, the presented results highlight a significant variability in sedimentary PAHs concentrations and compositional patterns within the studied Aegean Sea sub-regions. This could be likely attributed to a combination of distinct hydrological and biogeochemical characteristics, surface and near bottom water mass circulation patterns and the relative importance of PAH sources.

24415. 题目: Study of spectral characteristics of black carbon from biomass burning and source apportionment over Agartala in the northeastern India
文章编号: N20030505
期刊: Environmental Science and Pollution Research
作者: Parminder Kaur, Prasanth Srinivasan, Pranab Dhar, Barin Kumar De, Anirban Guha
更新时间: 2020-03-05
摘要: We have studied the black carbon (BC) mass concentrations, contributions from Fossil Fuels (FF), and Biomass burning (BB) to total BC mass concentrations using a 7-wavelength Aethalometer (Model, AE-31; Make, Magee Scientific, USA) at a rural continental location in the northeastern India. We have taken the continuous measurements of BC from January 2011 to December 2017 (excluding the year 2016 due to nonavailability of data). The annual mean BC concentration at 880 nm is observed maximum 12.56±5.06 µgm-3 in the year 2011 with a minimum of 7.26±2.76 µgm-3 during the year 2015. is the final sentence. BC, BCff, and BCbb mass concentrations show significant variation during morning, afternoon, evening, and night hours. The significant monthly, seasonal, and annual variabilities in the BC concentration, equivalent BC from FF and BB, are due to seasonal change in the emission sources, boundary layer dynamics, and dispersion and dilution conditions. The determination of Angstrom exponent (α) for the BC emitted during burning of different biofuels by performing a burning experiment is an important part of the present study. We have conducted a survey in and around the study location to know the different biofuels used by the people for daily household activities, and those biofuels are used in the burning experiment. As a result of biomass burning experiment to determine Angstrom exponent, we have found the α values to be ranging from 1.20 to 2.37 for flaming and a range from 1.59 to 2.33 for smoldering conditions for different biofuels. Annual mean contributions of BCff and BCbb to the total BC are found to be dominated by FF emissions during the whole study period. The percentage contribution of BCff and BCbb is found to be 56% and 44% during winter season due to increase in wood and biomass burning activities for various purposes. We have found the higher percentage contribution from BCff (85%) during monsoon season due to reduction in usage of biofuels.

24416. 题目: Short‐term changes in polysaccharide utilization mechanisms of marine bacterioplankton during a spring phytoplankton bloom
文章编号: N20030504
期刊: Environmental Microbiology
作者: Greta Reintjes, Bernhard M. Fuchs, Mirco Scharfe, Karen H. Wiltshire, Rudolf Amann, Carol Arnosti
更新时间: 2020-03-05
摘要: Spring phytoplankton blooms in temperate environments contribute disproportionately to global marine productivity. Bloom‐derived organic matter, much of it occurring as polysaccharides, fuels biogeochemical cycles driven by interacting autotrophic and heterotrophic communities. We tracked changes in the mode of polysaccharide utilization by heterotrophic bacteria during the course of a diatom‐dominated bloom in the German Bight, North Sea. Polysaccharides can be taken up in a 'selfish' mode, where initial hydrolysis is coupled to transport into the periplasm, such that little to no low molecular weight (LMW) products are externally released to the environment. Alternatively, polysaccharides hydrolyzed by cell‐surface attached or free extracellular enzymes (external hydrolysis) yield LMW products available to the wider bacterioplankton community. In the early bloom phase, selfish activity was accompanied by low extracellular hydrolysis rates of a few polysaccharides. As the bloom progressed, selfish uptake increased markedly, and external hydrolysis rates increased, but only for a limited range of substrates. The late bloom phase was characterized by high external hydrolysis rates of a broad range of polysaccharides, and reduced selfish uptake of polysaccharides, except for laminarin. Substrate utilization mode is related both to substrate structural complexity and to the bloom‐stage dependent composition of the heterotrophic bacterial community. This article is protected by copyright. All rights reserved.

24417. 题目: Enhanced Microalgal Harvesting Using Microalgae-Derived Extracellular Polymeric Substance as Flocculation Aid
文章编号: N20030503
期刊: ACS Sustainable Chemistry & Engineering
作者: Lin Yang, Haiyang Zhang, Shaozhe Cheng, Wen Zhang, Xuezhi Zhang
更新时间: 2020-03-05
摘要: Coagulation-based harvesting has been widely used in microalgal biomass harvesting. However, the coagulant contamination in the harvested biomass may negatively affect the applications in feedstock processing for food, feed, and fuel. In this study, extracellular polymeric substances (EPSs) were derived from microalgae, Scenedesmus acuminatus, and then used as a bioflocculant to aid the flocculation of the same algae. The results show that the alum coagulant (Al3+) usage was significantly reduced from 77.6 to 4.5 mg g–1 when adding this EPS bioflocculant at a dose of 3.2 mg g–1, which potentially reduces the chemical cost from $282 per metric ton to $71 per metric ton dry biomass that is harvested. To analyze the compositions of this bioflocculant, molecular fractionation was performed. The functional fractions such as protein-like and humic-like organic substances were characterized by fluorescence excitation–emission, followed by polysaccharide analysis. Low-MW (<3 kDa) EPS contributed to the flocculation process more than the large-MW fractions. Low-MW EPS contained higher contents of glucose and mannose in the polysaccharide that influence the interactions of the algae and the alum coagulant. Microalgal-derived bioflocculants may open up new avenue toward the low-cost and sustainable bioflocculation processes for algal and other biomass separation.

24418. 题目: Co-Pyrolysis of Maize Stover and Igneous Phosphate Rock to Produce Potential Biochar-Based Phosphate Fertilizer with Improved Carbon Retention and Liming Value
文章编号: N20030502
期刊: ACS Sustainable Chemistry & Engineering
作者: Akinson Tumbure, Peter Bishop, Mike Bretherton, Michael Hedley
更新时间: 2020-03-05
摘要: A biochar product that can supply the phosphorus (P) needs of growing crops will be highly advantageous for smallholder farmers in acidic, P-fixing, and P-deficient soils. In this study, nonreactive Dorowa phosphate rock (DPR) from Zimbabwe was added to maize residue (stems + leaves) at ratios of 1:2, 1:4, 1:6, and 1:8 (w/w) and pyrolyzed at 450 °C for 30 or 60 min to produce a suite of biochar-based fertilizers (BBFs). The total phosphorus, carbon, and nitrogen retention, biochar yields, liming value, and the amount of citric-soluble phosphate for these BBFs were assessed. After 60 min pyrolysis residence time, the 1:4, 1:6, and 1:8 mixtures yielded at least 26% more biochar yield, retained at least 43% more carbon, and retained up to 26% more nitrogen in the biochar compared to the pyrolysis of maize residues only. The citric soluble P of DPR increased up to 34 and 37% of the total P in the BBFs produced from the 1:6 and 1:8 DPR + maize mixes. This translated to more than a 30% increase in citric-soluble P compared to the unamended DPR. The BBFs show promising potential for supplying the P needs of growing crops, with about 2.1 t of the BBF (1:6 initial mix) being needed to supply 40 kg of citric-soluble P. The alkaline BBFs (pH > 10.2) had calcium carbonate equivalent values that ranged from 9.19 to 19.14 and are more suited for application to P-deficient, acidic soils. Glasshouse and field agronomic testing are recommended.

24419. 题目: Downward transport of naturally-aged light microplastics in natural loamy sand and the implication to the dissemination of antibiotic resistance genes
文章编号: N20030501
期刊: Environmental Pollution
作者: Xinyu Yan, Xinyao Yang, Zhang Tang, Jingjing Fu, Fangmin Chen, Ying Zhao, Lili Ruan, Yuesuo Yang
更新时间: 2020-03-05
摘要: Current understanding on the fate and behavior of microplastics (MPs) in complex soil media remains inadequate. We characterized the aging and hetero-aggregation of a MP sampled in farmland soil, and explored its vertical downward transport in natural loamy sand. The MP was identified with FTIR spectrum as polypropylene, a plastic lighter than water. FTIR spectrum combined with SEM imaging confirmed the MP was highly aged, generating colloidal plastic fibers and carbonyl groups. SEM imaging coupled with EDX analysis suggested hetero-aggregation of the MP with soil minerals. Soil leaching tests performed with the clean MP (without soil minerals) (CMP), the raw MP (RMP) (with soil minerals), and the RMP with humic acid (HA) (RMP + HA) demonstrated that the mobility was insignificant for the CMP, moderate for the RMP and highest for the RMP + HA, resulting in a maximal downward traveling distance of 0 cm, 3–4 cm, and 9–10 cm, respectively. Correlation between the maximal traveling distance and zeta potential of the CMP, RMP, and RMP + HA confirmed surface charge as a dominant control on the MP mobility; while the increasing density of the MP, due to hetero-aggregation with soil minerals, was identified as a driving mechanism for its downward transport, despite its intrinsic density lower than water. Occurrence of only the lower-sized rod-shaped plastic fibers at the maximal traveling distance suggested the natural aging, a process leading to plastic vibration and fragmentation, was conducive to plastic translocation. The three explored classes of antibiotic resistance genes (ARGs) (tetracycline, beta-lactam and sulfonamide) were all detected in the plastic surface, suggesting the MP may function as a potential pathway for the dissemination of ARGs to the deeper soil layer. These findings are important to understand the concentration distribution of both the MPs and ARGs in agriculture impacted soils, a natural reservoir of both emerging contaminants.

24420. 题目: Animal carcass- and wood-derived biochars improved nutrient bioavailability, enzyme activity, and plant growth in metal-phthalic acid ester co-contaminated soils: A trial for reclamation and improvement of degraded soils
文章编号: N20030415
期刊: Journal of Environmental Management
作者: Hanbo Chen, Xing Yang, Hailong Wang, Binoy Sarkar, Sabry M. Shaheen, Gerty Gielen, Nanthi Bolan, Jia Guo, Lei Che, Huili Sun, Jörg Rinklebe
更新时间: 2020-03-04
摘要: Reclamation of degraded soils such as those with low organic carbon content and soils co-contaminated with toxic elements and phthalic acid esters (PAEs) is of great concern. Little is known about the efficiency of plant- and animal-derived biochars for improving plant growth and physicochemical and biological properties of co-contaminated soils, particularly under low content of organic matter. Hence, a pot trial was carried out by growing pak choi (Brassica chinensis L.) to assess the influence of different doses (0, 0.5, 1, 2, and 4%) of animal (pig carcass) and wood (Platanus orientalis) derived biochars on soil properties, nutrient availabilities, plant growth, and soil enzyme activities in two soils containing low (LOC) and high (HOC) organic carbon contents and co-contaminated with di-(2-ethylhexyl) phthalic acid (DEHP) and cadmium (Cd). Biochar applications improved pH, salinity, carbon content, and cation exchange capacity of both soils. Addition of biochars significantly increased the bioavailability and uptake of phosphorus and potassium in the plants in both soils with greater effects from pig biochar than wood biochar. Biochar additions also significantly enhanced urease, sucrase, and catalase activities, but suppressed acid phosphatase activity in both soils. The impact of pig biochar was stronger on urease and acid phosphatase, while the wood biochar was more effective with sucrase and catalase activities. The biomass yield of pak choi was significantly increased after biochar addition to both soils, especially in 2% pig biochar treatment in the LOC soil. The positive response of soil enzymes activities and plant growth for biochar addition to the Cd and DEHP co-contaminated soils indicate that both biochars, particularly the pig biochar can mitigate the risk of these pollutants and prove to be eco-friendly and low-cost amendments for reclaiming these degraded soils.