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19941. 题目: Siderophore-promoted dissolution of ferrihydrite associated with adsorbed and coprecipitated natural organic matter
文章编号: N18090701
期刊: Organic Geochemistry
作者: Christine Poggenburg, Robert Mikutta, Patrick Liebmann, Markus Koch, Georg Guggenberger
更新时间: 2018-09-07
摘要: Acquisition of Fe(III) from hardly soluble Fe oxyhydroxides by bacteria, fungi, and plants in the soil is often facilitated by Fe(III)-chelating siderophores. While the siderophore-promoted dissolution of pure Fe oxyhydroxides and the influence of defined low molecular weight organic acids has been investigated meticulously, studies examining Fe oxyhydroxides coated with more complex adsorbed organic matter (OM) or Fe-OM coprecipitates have been sparse. This study therefore explored the impact of the composition of both adsorbed and coprecipitated OM on the siderophore-promoted dissolution of ferrihydrite (Fh) in relation to (i) surface site coverage and pore blockage, (ii) aggregation state, (iii) charge characteristics, and (iv) crystallinity. In addition to pure Fh, Fh-OM adsorption complexes and Fe-OM coprecipitates were synthesized using OM of different origin (extracellular polymeric substances of Bacillus subtilis, natural OM (NOM) extracted from soil Oi and Oa horizons). The Fe-organic associations were characterized by N2 gas adsorption, X-ray photoelectron spectroscopy (XPS), electrophoretic mobility, particle size measurements and desorption experiments. Siderophore-mediated dissolution experiments with desferrioxamine-B (DFOB) were conducted at pH 4 and 7. At pH 4, adsorbed OM provided a more effective protection against DFOB due to its larger sorption affinity. At pH 7, the surface site blockage by adsorbed OM at comparable C loadings was less effective, while less aggregated particles were more prone to dissolution. For OM coprecipitated with Fe, there was no distinct accelerating or inhibiting effect on DFOB-promoted dissolution to be found. Initial Fe dissolution rates at given soil conditions were thus affected by both the type of OM and the sorption procedure. Our results therefore corroborate the importance of considering the heterogeneous composition of soil OM when investigating the mobilization of Fe-organic associations.
19942. 题目: Dissolved Black Carbon as an Efficient Sensitizer in the Photochemical Transformation of 17ß-Estradiol in Aqueous Solution
文章编号: N18090615
期刊: Environmental Science & Technology
作者: Zhicheng Zhou, Beining Chen, Xiaolei Qu, Heyun Fu, Dongqiang Zhu
更新时间: 2018-09-06
摘要: Dissolved black carbon (DBC) is an important component of the dissolved organic matter (DOM) pool. Nonetheless, little is known about its role in the photochemical processes of organic contaminants. This study investigated the effect of DBC on the phototransformation of 17β-estradiol in aqueous solutions under simulated sunlight. Four well-studied dissolved humic substances (DHS) were included as comparisons. DBC acted as a very effective sensitizer to facilitate the phototransformation of 17β-estradiol. The apparent quantum yield for 17β-estradiol phototransformation mediated by DBC was approximately six times higher than that by DHS at the same carbon concentration. Quenching experiments suggested that direct reaction with triplet-excited state DBC (3DBC*) was the predominant pathway of 17β-estradiol phototransformation. The higher mediation efficiency of DBC than DHS is likely due to the higher contents of aromatic groups and smaller molecular sizes, which facilitated the generation of 3DBC*. The apparent quantum yield of triplet-excited states production for DBC was 4–8 times higher than that for DHS. The results suggest that 3DBC* may have a considerable contribution to the overall photoreactivity of triplet-excited state DOM in aquatic systems. Our findings also imply that DBC can play an important role in the phototransformation of organic contaminants in the environments.
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19943. 题目: Negative priming effect of three kinds of biochar on the mineralization of native soil organic carbon
文章编号: N18090614
期刊: Land Degradation & Development
作者: Yuxue Liu, Ying Chen, Yuying Wang, Haohao Lu, Lili He, Shengmao Yang
更新时间: 2018-09-06
摘要: This study was conducted to improve our understanding of the effect of biochar on the degradation of original soil organic carbon (SOC) and the resulting net C sequestration. A 120 d incubation experiment was conducted to detect the CO2 evolution from soil amended with three kinds of biochar, namely rice husk biochar (RH), pecan shell biochar (PS), and bamboo biochar (BB), at biochar to soil ratios of 0% (as control), 1%, 2%, and 5%, as well as 100% pure biochar, and to evaluate their priming effect on SOC mineralization. Results showed that the cumulative mineralized amounts of SOC decreased by 7.95–10.7% with 5% RH, PS, and BB treatments, while there were no significant differences in 1% or 2% biochar treatments after 120 d of incubation compared to the control. Biochar had a suppressing influence on native SOC decomposition, and the effect increased with the amount of applied biochar increasing. The negative priming effect of biochar on the mineralization of SOC was mainly observed after 15 d of incubation, and increased with incubation time. The negative effects of BB and RH were significantly stronger than that of PS at the 5% application ratio. This was mainly due to the less pores and smaller specific surface area of PS, which resulted in the weaker encapsulation and adsorption protection effect of PS than RH and BB, and inhibited the degradation of the adsorbed native SOC. Therefore, BB and RH have great potential for C sequestration and mitigation, especially in soils with low organic C.
19944. 题目: Accumulation of Terrestrial Dissolved Organic Matter Potentially Enhances Dissolved Methane Levels in Eutrophic Lake Taihu, China
文章编号: N18090613
期刊: Environmental Science & Technology
作者: Yongqiang Zhou, Qitao Xiao, Xiaolong Yao, Yunlin Zhang, Mi Zhang, Kun Shi, Xuhui Lee, David C. Podgorski, Boqiang Qin, Robert G. M. Spencer, Erik Jeppesen
更新时间: 2018-09-06
摘要: Inland waters play an important role for the storage of chromophoric dissolved organic matter (CDOM) and outgassing of methane (CH4). However, to date, linkages between the optical dynamics of CDOM and dissolved CH4 levels remain largely unknown. We used multi-year (2012−2014) seasonal data series collected from Lake Taihu and 51 connecting channels to investigate how CDOM optical dynamics may impact dissolved CH4 levels in the lake. High dissolved CH4 in the northwestern inflowing river mouths coincided with high underwater UV–vis light availability, dissolved organic carbon (DOC), chemical oxygen demand (COD), DOM aromaticity, terrestrial humic-rich fluorescence, in situ measured terrestrial CDOM, depleted dissolved oxygen (DO), stable isotopic δ2H, and δ18O compared with other lake regions. Our results further revealed positive relationships between dissolved CH4 and CDOM absorption at 350 nm, i.e. a(350), COD, DOC, terrestrial humic-rich fluorophores, and DOM aromaticity, and negative relationships between dissolved CH4 and DO, δ2H, and δ18O. The central lake samples showed a major contribution of terrestrial-sourced molecular formulas to the ultrahigh resolution mass spectrometry data, suggesting the presence of allochthonous DOM sources even here. We conclude that an elevated terrestrial CDOM input likely enhances dissolved CH4 levels in Lake Taihu.
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19945. 题目: Performance and kinetic model of degradation on treating pharmaceutical solvent wastewater at psychrophilic condition by a pilot-scale anaerobic membrane bioreactor
文章编号: N18090612
期刊: Bioresource Technology
作者: Zhaobo Chen, Jiao Xu, Dongxue Hu, Yubo Cui, Pan Wu, Hui Ge, Fuquan Jia, Tingting Xiao, Xue Li, Haiyan Su, Haixu Wang, Ying Zhang
更新时间: 2018-09-06
摘要: A pilot-scale anaerobic membrane bioreactor (AnMBR) was operated for 435 days in this study, aiming to treat pharmaceutical solvent wastewater containing m-Cresol (MC), isopropanol (IPA) and N,N-Dimethylformamide (DMF) pollutants at different temperatures of 35 ± 3 °C, 25 ± 3 °C, 15 ± 3 °C and 25 ± 3 °C, respectively. The reactor reached average total removal efficiencies of about 96%, 97.2% and 98% of MC, IPA and DMF at psychrophilic condition (15 ± 3 °C). Higher physical removal rate was obtained at 15 ± 3 °C due to the important contribution of membrane filtration. At this stage, the biogas production, methane content and specific methanogenic activity and extracellular polymeric substances of suspended sludge were observed with the lowest level. Moreover, the kinetic models for solvent degradation were established at different temperatures, results showed the smaller maximum specific substrate degradation rate of MC and IPA, besides, the lowest degradation rate of three solvents were obtained at 15 ± 3 °C.
19946. 题目: Impacts of energy distribution and electric field on membrane fouling control in microbial fuel cell-membrane bioreactor (MFC-MBR) coupling system
文章编号: N18090611
期刊: Bioresource Technology
作者: Yufei Wang, Hui Jia, Jie Wang, Benai Cheng, Guang Yang, Fei Gao
更新时间: 2018-09-06
摘要: To investigate the influence of energy allocation on membrane fouling, three coupling systems at different concentrations of mixed liquid suspended solids (MLSS) and a control system without microbial fuel cell (MFC) were established. The results show that MFC acted negative effect in low-loading stage (0.59 kg-COD·m−3·d−1), while high MLSS acted active effect on organics degradation in high-loading stage (2.00 kg-COD·m−3·d−1), and electric field could be a positive factor with sufficient energy. Besides, membrane filtration experiments in the electric field with microbial contaminants indicate that soluble microbial products (SMP) and loosely bound extracellular polymeric substances (LB-EPS) had greater tendencies to cause irreversible membrane fouling. SMP and the residual cell liquid (Cell) were more susceptible than extracellular polymeric substances (EPS), demonstrating that the irreversible fouling was reduced mainly due to SMP decrease in the electric field.
19947. 题目: Evaluation of the action of Tween 20 non-ionic surfactant during enzymatic hydrolysis of lignocellulose: Pretreatment, hydrolysis conditions and lignin structure
文章编号: N18090610
期刊: Bioresource Technology
作者: Yu-An Chen, Yan Zhou, Yanlin Qin, Dehua Liu, Xuebing Zhao
更新时间: 2018-09-06
摘要: The aim of this work was to study the effects of pretreatment process, hydrolysis condition and structural features of lignin on the improving action of surfactants (Tween 20) for enzymatic hydrolysis of pretreated wheat straw, and further to interpret the relation of these factors with the non-productive adsorption of cellulases on lignin. Tween 20 seemed to be more greatly improve cellulose conversion under harsher conditions. The surfactant showed more significant improvement for acid-pretreated substrates than oxidative-pretreated substrates. Highly-condensed lignin and phenolic hydroxyl groups showed much stronger adsorption ability to cellulases, while Tween 20 could well block the lignin–cellulase interactions recovering cellulose hydrolyzability. It was proposed that pretreatments altered lignin structures, resulting in the change of surface properties thus further impacting the lignin–cellulase interactions. Addition of Tween 20 could modify lignin surface properties to change its hydrophobicity, hydrogen bonding ability and surface charges, thus reducing the non-productive adsorption of proteins.
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19948. 题目: Fast screening compositions of PM2.5 by ATR-FTIR: Comparison with results from IC andOC/EC analyzers
文章编号: N18090609
期刊: Journal of Environmental Sciences
作者: Xu Yu, Wei Song, Qingqing Yu, Sheng Li, Ming Zhu, Yanli Zhang, Wei Deng, Weiqiang Yang, Zhonghui Huang, Xinhui Bi, Xinming Wang
更新时间: 2018-09-06
摘要: Chemical speciation of fine particles or PM2.5 collected on filters is still a costly and time-consuming task. In this study, filter-based PM2.5 samples were collected during November–December 2013 at four sites in Guangzhou, and the major components were fast screened (~ 7 min per filter sample) by Attenuated Total Reflectance (ATR)-Fourier Transform Infrared Spectroscopic (FTIR) in comparison with that measured by Organic carbon/Element carbon (OC/EC) analyzer and Ion Chromatography (IC). The concentrations of nitrate, ammonium, sulfate, primary organic carbon (POC) and secondary organic carbon (SOC) measured by OC/EC and IC analyzers were better correlated with their infrared absorption peak heights at 1320 cm-1 for nitrate, 1435, 3045 and 3215 cm-1 for ammonium, 615 cm-1 for sulfate, 690, 760 and 890 cm-1 for POC and 1640 and 1660 cm-1 for SOC respectively, during polluted days (PM2.5 > 75 μg/m3) than during clean days (PM2.5 ≤ 75 μg/m3). With the evolution of a haze episode during our field campaign, the concentrations of the major PM2.5 components displayed consistent variations with their infrared absorption peak heights, suggesting ATR-FTIR could be a fast and useful technique to characterize filter-based PM2.5 compositions particularly during pollution events although cautions should be taken when PM2.5 levels are low. Notably, elevated PM2.5 mass concentrations occurred with enhanced ratios of [NO3−]/[SO42 −] and [NH4+]/[SO42 −], implying that nitrogenous components play vital roles in the PM2.5 pollution events in the study region.
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19949. 题目: Chemical characterization of fine and ultrafine PM, direct and indirect genotoxicity of PM and their organic extracts on pulmonary cells
文章编号: N18090608
期刊: Journal of Environmental Sciences
作者: Sylvain Billet, Yann Landkocz, Perrine J. Martin, Anthony Verdin, Frédéric Ledoux, Capucine Lepers, Véronique André, Fabrice Cazier, François Sichel, Pirouz Shirali, Pierre Gosset, Dominique Courcot
更新时间: 2018-09-06
摘要: Particulate matter in ambient air constitutes a complex mixture of fine and ultrafine particles composed of various chemical compounds including metals, ions, and organics. A multidisciplinary approach was developed by studying physico-chemical characteristics and mechanisms involved in the toxicity of particulate atmospheric pollution. PM0.3–2.5 and PM2.5 including ultrafine particles were sampled in Dunkerque, a French industrialized seaside city. PM samples were characterized from a chemical and toxicological point of view. Physico-chemical characterization evidenced that PM2.5 comes from several sources: natural ones, such as soil resuspension and marine sea-salt emissions, as well as anthropogenic ones, such as shipping traffic, road traffic, and industrial activities. Human BEAS-2B lung cells were exposed to PM0.3–2.5, or to the Extractable Organic Matter (EOM) of PM0.3–2.5 and PM2.5. These exposures induced several mechanisms of action implied in the genotoxicity, such as oxidative DNA adducts and DNA Damage Response. The toxicity of PM-EOM was higher for the sample including the ultrafine fraction (PM2.5) containing also higher concentrations of polycyclic aromatic hydrocarbons. These results evidenced the major role of organic compounds in the toxicity of PM.
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19950. 题目: Characteristics of the pollutant emissions in a tunnel of Shanghai on a weekday
文章编号: N18090607
期刊: Journal of Environmental Sciences
作者: Rui Li, Ya Meng, Hongbo Fu, Liwu Zhang, Xingnan Ye, Jianmin Chen
更新时间: 2018-09-06
摘要: Tunnel displays a typical semi-closed environment, and multitudes of the pollutants tend to accumulate. The samples of gaseous pollutants and particulate matter (PM) were collected from the Xiangyin tunnel at Shanghai to investigate the characteristics of the pollutant emissions. The results indicated that both gaseous pollutants and PM exhibited much higher concentrations during the rush hours in the morning and at night due to vehicle emission. Two peaks of the PM concentration were observed in the scope of 0.7‐1.1 and 3.3–4.7 μm, accounting for 14.6% and 20.3% of the total concentrations, respectively. Organic matter (OM), EC, and many water-soluble ions were markedly higher at the rush hours in the morning than those at night, implicating comprehensive effects of vehicle types and traffic volume. The particle number concentrations exhibited two peaks at Aitken mode (25 nm and 100 nm) and accumulation mode (600 nm), while the particle volume concentration displayed high values at the accumulation mode (100–500 nm) and coarse mode (2.5–4.0 μm). The peak around 100 nm was detected in the morning rush hours, but it diminished with the decrease of the traffic volume. Individual-particle analysis revealed that main particles in the tunnel were Fe-rich particles, K-rich particles, mineral particles, Ca–S rich particles and Al–Si particles. The particles collected at the rush hours displayed marked different morphologies, element concentrations and particle sizes compared to the ones collected at the non-rush period. The data presented herein could shed a light on the feature of vehicle emissions.
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19951. 题目: Atmospheric HULIS and its ability to mediate the reactive oxygen species (ROS): A review
文章编号: N18090606
期刊: Journal of Environmental Sciences
作者: Myat Sandar Win, Zhengyang Tian, Hui Zhao, Kai Xiao, Jiaxian Peng, Yu Shang, Minghong Wu, Guangli Xiu, Senlin Lu, Shinich Yonemochi, Qingyue Wang
更新时间: 2018-09-06
摘要: Atmospheric humic-like substances (HULIS) are not only an unresolved mixture of macro-organic compounds but also powerful chelating agents in atmospheric particulate matters (PMs); impacting on both the properties of aerosol particles and health effects by generating reactive oxygen species (ROS). Currently, the interests of HULIS are intensively shifting to the investigations of HULIS-metal synergic effects and kinetics modeling studies, as well as the development of HULIS quantification, findings of possible HULIS sources and generation of ROS from HULIS. In light of HULIS studies, we comprehensively review the current knowledge of isolation and physicochemical characterization of HULIS from atmospheric samples as well as HULIS properties (hygroscopic, surface activity, and colloidal) and possible sources of HULIS. This review mainly highlights the generation of reactive oxygen species (ROS) from PMs, HULIS and transition metals, especially iron. This review also summarized the mechanism of iron-organic complexation and recent findings of OH formation from HULIS-metal complexes. This review will be helpful to carry out the modeling studies that concern with HULIS-transition metals and for further studies in the generation of ROS from HULIS-metal complexes.
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19952. 题目: Reforestation of agricultural land in the tropics: The relative contribution of soil, living biomass and debris pools to carbon sequestration
文章编号: N18090605
期刊: Science of The Total Environment
作者: Tom Lewis, Luke Verstraten, Bruce Hogg, Bernhard J. Wehr, Scott Swift, Neil Tindale, Neal W. Menzies, Ram C. Dalal, Philippa Bryant, Ben Francis, Timothy E. Smith
更新时间: 2018-09-06
摘要: Tropical regions of the world experience high rates of land-use change and this has a major influence on terrestrial carbon (C) pools and the global C cycle. We assessed land-use change from agriculture to reforested plantings (with endemic species), up to 33 years of age, using 10 paired sites in the wet tropics, Australia. We determined the impacts on 0–50 cm below-ground C (soil organic C (SOC), charcoal C, humic organic C, particulate organic C, resistant organic C), C stored in roots (fine and coarse), C stored in living above-ground biomass and debris C pools. Reforested areas accumulated ecosystem C at a rate of 7.4 Mg ha−1 yr−1. Reforestation plantings contained, on average, 2.3 times more ecosystem C than agricultural areas (102 Mg ha−1 and 233 Mg ha−1, respectively). Most of the C accumulation was in living above-ground and below-ground biomass (60 and 30%, respectively) with a smaller amount in debris pools (16%). Apart from C in roots, soil C accumulation was not obvious across sites ranging from 8 to 33 years since reforestation, relative to the agricultural baseline. Differences in SOC (and associated SOC pools) to a depth of 50 cm, did exist between reforested areas and adjacent agriculture at some sites, however there was not a consistent trend in SOC associated with reforestation. Local site-based factors (e.g. soil texture and mineralogy, land-use history and microbial activity) appear to have a strong influence on the direction of the change in SOC. While reforestation in the tropics has great potential to accumulate C in biomass in living vegetation, and debris pools, it is likely to take approximately 50 years before C stocks of reforested areas resemble natural ecosystems. Accumulation of SOC through reforestation is difficult to achieve, highlighting the need to conserve carbon pools in remnant forests in the tropics.
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19953. 题目: Aquatic organic matter: Classification and interaction with organic microcontaminants
文章编号: N18090604
期刊: Science of The Total Environment
作者: Vanda Artifon, Eliete Zanardi-Lamardo, Gilberto Fillmann
更新时间: 2018-09-06
摘要: Organic matter (OM) in aquatic system is originated from autochthonous and allochthonous natural sources as well as anthropogenic inputs, and can be found in dissolved, particulate or colloidal form. According to the type/composition, OM can be divided in non-humic substances (NHS) or humic substances (HS). The present review focuses on the main groups that constitute the NHS (carbohydrates, proteins, lipids, and lignin) and their role as chemical biomarkers, as well as the main characteristics of HS are presented. HS functions, properties and mechanisms are discussed, in addition to their association to the fate, bioavailability, and toxicity of organic microcontaminants in the aquatic systems. Despite the growing diversity and potential impacts of organic microcontaminants to the aquatic environment, limited information is available about their association with OM. A protective effect is, however, normally seen since the presence of OM (HS mainly) may reduce bioavailability and, consequently, the concentration of organic microcontaminants within the organism. It may also affect the toxicity by either absorbing ultraviolet radiation incidence and, then, reducing the formation of phototoxic compounds, or by increasing the oxygen reactive species and, thus, affecting the decomposition of natural and anthropogenic organic compounds. In addition, the outcome data is hard to compare since each study follows unique experimental protocols. The often use of commercial humic acid (Aldrich) as a generic source of OM in studies can also hinder comparisons since differences in composition makes this type of OM not representative of any aquatic environment. Thus, the current challenge is find out how this clear fragmentation can be overcome.
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19954. 题目: Nutrient supply enhanced wheat residue-carbon mineralization, microbial growth, and microbial carbon-use efficiency when residues were supplied at high rate in contrasting soils
文章编号: N18090603
期刊: Soil Biology and Biochemistry
作者: Yunying Fang, Bhupinder Pal Singh, Damian Collins, Bingzhi Li, Jiang Zhu, Ehsan Tavakkoli
更新时间: 2018-09-06
摘要: Crop residue is a source of energy and nutrients for microbial growth, and can be converted into soil organic matter (SOM). However, there are still knowledge gaps on how the interaction of crop residue and supplementary nutrients (nitrogen, phosphorus and sulfur) influence the fate of residue in microbial biomass carbon (MBC) and microbial use efficiency. Here, we quantified the carbon (C) mineralization of wheat residue (δ13C 494‰) and microbial C use efficiency at ecosystem scale (CUEE) with two levels of the residue (6.7 and 20.0 g kg−1 soil) and three levels of nutrients in Luvisol and Vertisol under a controlled laboratory condition (22 °C). Between 48 and 61% of residue-C was mineralized over 245 days. The residue CUEE was similar across the two levels of the residue on day 3 (i.e., 0.29–0.40 in the Luvisol and 0.41–0.50 in the Vertisol) and then decreased over time, likely because of greater increase in cumulative total respiration and microbial turnover, relative to microbial growth. The residue CUEE was 20–55% lower in the high-residue, compared with (cf.) low-residue, input after day 10, which may have resulted from the greater loss of C via overflow respiration (microbial respiration without the production of energy) and turnover of high MBC. Narrowing of the C-nutrient imbalance increased residue-C mineralization, residue-derived MBC, and residue CUEE only under the high-residue input scenario where nutrients were possibly a limiting factor for microbial growth. Consequently, the results indicate a higher efficiency of SOM formation from returning of residue to soils under (i) low-residue (cf. high-residue) with or without nutrients, and (ii) high-residue with nutrient inputs (cf. no nutrient). The findings of the integrated residue–nutrient management on dynamics of residue-derived MBC and residue CUEE can be used to improve predictive performance of the models on specific soil functions such as SOM storage in agro-ecosystems.
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19955. 题目: Conversion to bioenergy crops alters the amount and age of microbially-respired soil carbon
文章编号: N18090602
期刊: Soil Biology and Biochemistry
作者: Laura M. Szymanski, Gregg R. Sanford, Kate Heckman, Randall D. Jackson, Erika Marín-Spiotta
更新时间: 2018-09-06
摘要: Bioenergy cropping systems have the potential to supply plant biomass as lignocellulosic feedstock for biofuels and bioproducts that will reduce reliance on fossil energy. Identifying the effects of alternative bioenergy cropping systems on soil carbon (C) is necessary to assess the sustainability of renewable fuels. We measured the response of soil organic carbon (SOC) pools to four bioenergy cropping systems using soils collected at the establishment of the field trials and after five years in two soils of contrasting texture: a fine-textured silt loam (Mollisol) in south central Wisconsin and a coarse-textured sandy loam (Alfisol) in southwestern Michigan, USA. Crop management followed region-specific practices with no till with the intention of reducing soil C losses from cultivation. Cropping systems included an annual monoculture (continuous corn), two perennial monocultures (switchgrass and hybrid poplar), and a perennial polyculture (restored native prairie). Using a 365-d laboratory soil incubation and a three-pool model, we estimated sizes and turnover times of SOC in surface (0–10 cm) and deeper soils (25–50 cm). After five years, all soils had less bioavailable C as measured by microbial respiration. To determine potential differences in soil C turnover under annual and perennial monocultures, we measured radiocarbon abundance (14C) of bulk soils and respired CO2 under corn and switchgrass. Respired-CO2 was more depleted in 14C over time, indicating preferential respiration of relatively “old C” after five years. Decreased microbial respiration rates after five years of bioenergy cropping systems offer the potential for the eventual reduction of soil C losses after conversion to no till. However, the 14C-CO2 data suggest that previously-protected C pools may become depleted over time, especially with continued removal of plant inputs. Results show that conversion of conventional field-crop agriculture to bioenergy cropping systems may not provide belowground C benefits in the short term, as indicated by reductions in the size of the active pool. Reduced total soil respiration over the length of the study, as well as system-specific differences in soil respiration (monoculture annuals < monoculture perennial < polyculture perennials), suggest C loss may decline in perennial polycultures systems as they age. SOM pools responded differently to bioenergy crop management on soils with contrasting texture, highlighting the importance of geography in predicting belowground consequences of intensified agricultural production.
19956. 题目: Modeling emerging contaminants breakthrough in packed bed adsorption columns by UV absorbance and fluorescing components of dissolved organic matter
文章编号: N18090601
期刊: Water Research
作者: Massimiliano Sgroi, Tarun Anumol, Paolo Roccaro, Federico G.A. Vagliasindi, Shane A. Snyder
更新时间: 2018-09-06
摘要: This study investigated, using rapid small-scale column testing, the breakthrough of dissolved organic matter (DOM) and eleven emerging organic contaminants (EOCs) during granular activated carbon (GAC) filtration of different water qualities, including wastewater, surface water and synthetic water (riverine organic matter dissolved in deionized water). Fluorescing organic matter was better adsorbed than UV absorbance at 254 nm (UV254) and dissolved organic carbon (DOC) in all tested water. Furthermore, highest adsorption of DOM (in terms of DOC, UV254 and fluorescence) was observed during wastewater filtration. UV absorbing DOM had fast and similar breakthrough in surface water and synthetic water, whereas fluorescence breakthrough was very rapid only in synthetic water. PARAFAC modeling showed that different fluorescing components were differently adsorbed during GAC process. Particularly, fluorescing components with maxima intensity at higher excitation wavelengths, which are corresponding to humic-like fluorescence substances, were better removed than other components in all waters. As opposed to DOM, EOCs were better adsorbed during synthetic water filtration, whereas the fastest EOCs breakthrough was observed during filtration of wastewater, which was the water that determined the highest carbon fouling. Exception was represented by long-chained perfluoroalkylated substances (i.e., PFOA, PFDA and PFOS). Indeed, adsorption of these compounds resulted independent of water quality. In this study was also investigated the applicability of UV254 and fluorescing PARAFAC components to act as surrogates in predicting EOCs removal by GAC in different water matrices. Empirical linear correlation for the investigated EOCs were determined with UV254 and fluorescing components in all water qualities. However, fluorescence measurements resulted more sensitive than UV254 to predict EOC breakthrough during GAC adsorption. When the data from all water qualities was combined, good correlations between the microbial humic-like PARAFAC component and EOC removals were still observed and they resulted independent of water quality if considering only real water matrices (wastewater and surface water). On the contrary, correlations between EOC removals and UV254 removals were independent of water quality when combining data of surface waters and synthetic water, but a different correlation model was needed to predict EOCs breakthrough in wastewater.
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19957. 题目: Influence of earthworms on the nitrogen transfer of sewage sludge in the vermifilter process
文章编号: N18090521
期刊: Environmental Science and Pollution Research
作者: Jian Yang, Wanyin Di, Jing Liu, Meiyan Xing
更新时间: 2018-09-05
摘要: A 6-year laboratory study was conducted to explore the performance of the vermifilter (VF) on reducing sewage sludge. Sewage sludge was found to be reduced significantly in the VF and exhibited a better performance of sludge reduction as compared with the conventional biofilter (BF), which could be traced through the nitrogen-rich organic matter. The nitrogen stable isotope technology was applied to study the matter flow of sewage sludge in the VF process and the influence of earthworms Eisenia fetida on sewage sludge reduction. Results showed that (1) the protein material could be consumed more than the polysaccharide and lipid materials, respectively, in the VF; (2) the presence of earthworms could enhance the consumption capacity of the VF on the protein-rich material of the sewage sludge; (3) earthworms played a leading role on the nitrogen lifting of the sewage sludge, leading to the performance difference of the effluent sludge or biofilm sludge between the VF and BF; (4) in the VF, nitrogen-isotope accumulation in either biofilms or earthworms happened more significantly in the lower layer than in the upper one, while nitrogen transfer of sewage sludge happened more significantly in the upper layer than in the lower one; (5) earthworms improved the feeding environment of organisms (microorganisms in biofilms, moth fly larvae, Limacidaes, and Lymnaeidaes); (6) biofilms, Limacidaes, and moth fly larvae performed better than leeches, Lymnaeidaes, and moth fly adults at nitrogen transfer of sewage sludge.
19958. 题目: Spatial and vertical variations in the soil organic carbon concentration and its controlling factors in boreal wetlands in the Greater Khingan Mountains, China
文章编号: N18090520
期刊: Journal of Soils and Sediments
作者: Weidong Man, Dehua Mao, Zongming Wang, Lin Li, Mingyue Liu, Mingming Jia, Chunying Ren, Igor Ogashawara
更新时间: 2018-09-05
摘要: Purpose: Wetlands have a critical impact on the global carbon cycle. This study aims to investigate the spatial and vertical distribution of the soil organic carbon concentration (SOCc), to identify the differences of SOCc among swamps, marshes, bogs, and fens at a regional scale, and finally to examine the main environmental factors impacting SOCc at different depth intervals within different wetland types located in the Greater Khingan Mountains (GKM). Materials and methods: A total of 218 soil samples were collected. SOCc was determined by the combustion-oxidation method. To analyze the impacts of wetland type, soil type, mean annual precipitation (MAP), mean annual temperature (MAT), evapotranspiration (ET), elevation (EL), and slope (SL) on SOCc, statistical analysis methods were executed, including ANOVA with the Duncan test, Pearson correlations analysis, and the stepwise multiple regressions analysis. Results and discussion: The mean values of SOCc in the 0–30, 30–60, and 60–100-cm intervals were 130.4, 64.2, and 32.6 g kg−1, respectively. The wetland type played an important role in the pattern of SOCc in terms of significant differences (p < 0.05) among the different wetland types in the 0–60-cm depth. However, significant differences were not found among different soil types. In terms of the wetland type, the highest SOCc was found in bogs (p < 0.05), probably due to the higher MAP and lower MAT. The increased MAP (R2 = 0.1369, p < 0.01) and decreased MAT (R2 = 0.1225, p < 0.01) had positive associations on the wetland SOCc. ET (R2 = 0.2809, p < 0.01), MAP (R2 = 0.2025, p < 0.01), and EL (R2 = 0.0484, p < 0.05) were positively correlated with marsh SOCc. Moreover, MAP was positively correlated with the bog SOCc (R2 = 0.1296, p < 0.01). For vertical patterns, SOCc was higher in the 0–30-cm interval and decreased with depth. The impacts of environmental factors on SOCc decreased with depth for each wetland type. Models were developed to document the relations between the SOCc of marshes and fens and corresponding environmental factors. Conclusions: Wetland types largely differed in the soil carbon pools in the GKM of China. The relative importance of environmental factors was different for the SOCc values of various wetland types. To minimize carbon loss into the atmosphere, more protections are required for wetlands, especially in the 0–30-cm depth interval because it contains higher SOCc values and is more vulnerable and less stable than those in the deeper layers.
19959. 题目: Organic layers favor phosphorus storage and uptake by young beech trees ( Fagus sylvatica L.) at nutrient poor ecosystems
文章编号: N18090519
期刊: Plant and Soil
作者: Simon Hauenstein, Harald Neidhardt, Friederike Lang, Jaane Krüger, Diana Hofmann, Thomas Pütz, Yvonne Oelmann
更新时间: 2018-09-05
摘要: Aims: The accumulation of organic layers in forests is linked to decreasing nutrient availability. Organic layers might represent a source of phosphorus (P) nutrition of trees in forests. Our aims were i) to test if the fate of P in a tree sapling-soil system differs between nutrient-poor and nutrient-rich sites, and ii) to assess the influence of organic layers on the fate of P in a tree sapling-soil system at either site. Methods: We conducted a 33P labeling experiment of mesocosms of beech (Fagus sylvatica) saplings. Results: Recovery of 33P in the organic layer was greater under nutrient-poor than under nutrient-rich conditions likely caused by the abundance of microorganisms and roots. Under nutrient-poor conditions, we found that the mobilization of P followed by efficient uptake promoted tree sapling growth if the organic layer was present. The presence of organic layers did not significantly influence P uptake by beech saplings under nutrient-rich conditions suggesting mechanisms of P mobilization in addition to organic matter mineralization. Conclusions: Our results highlight the importance of organic layers for P nutrition of young beech trees growing on nutrient-poor soils in temperate forest ecosystems. The role of organic layers should be considered for sustainable forest management.
19960. 题目: Magnetic biochar-based manganese oxide composite for enhanced fluoroquinolone antibiotic removal from water
文章编号: N18090518
期刊: Environmental Science and Pollution Research
作者: Ruining Li, Zhaowei Wang, Xiating Zhao, Xi Li, Xiaoyun Xie
更新时间: 2018-09-05
摘要: Magnetic biochar-based manganese oxide composite (MMB) and raw biochar (BC) were synthesized via pyrolysis at a temperature of 500 °C under anoxic conditions of potato stems and leaves, characterized, and successfully used for the removal of norfloxacin (NOR), ciprofloxacin (CIP), and enrofloxacin (ENR) as representative compounds of fluoroquinolone antibiotics (FQs). Characterization results suggested that Fe3O4 and MnOx are the dominant crystals in MMB. MMB possessed large surface area and pore volume than BC. Batch adsorption experiments showed that the maximum adsorption abilities of MMB for norfloxacin (NOR), ciprofloxacin (CIP), and enrofloxacin (ENR) were 6.94, 8.37, and 7.19 mg g−1. In comparison to BC, the adsorption abilities of MMB increased 1.2, 1.5, and 1.6 times for NOR, CIP, and ENR, respectively. The pseudo-second-order kinetic model and the Langmuir model correlated satisfactorily to the experimental data. Thermodynamic studies revealed that the adsorption processes were spontaneous and endothermic. The adsorption capacity of MMB decreased with increasing solution pH (between 3.0 and 10.0) and increasing ionic strength (0.001–0.1). The MMB with high FQ removal efficiency, easy separation, and desirable regeneration ability may have promising environmental applications for the removal of fluoroquinolone antibiotics from water environment.