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24561. 题目: Cellular and non-cellular mineralization of organic carbon in soils with contrasted physicochemical properties
文章编号: N18080402
期刊: Soil Biology and Biochemistry
作者: Benoit Kéraval, Sébastien Fontaine, Audrey Lallement, Sandrine Revaillot, Hermine Billard, Gaël Alvarez, Fernando Maestre, Christian Amblard, Anne-Catherine Lehours
更新时间: 2018-08-04
摘要: It has been recently demonstrated that soil organic carbon (SOC) mineralization is supported by intracellular respiration of heterotrophic microorganisms and by non-cellular oxidative processes. However, little is known about the prevalence and drivers of non-cellular SOC mineralization among soils. In this study, untreated and gamma-irradiated soils sampled along a latitudinal gradient and exhibiting contrasted physicochemical properties were incubated in order to quantify potential non-cellular SOC mineralization and to identify its sensibility to soil properties. In sterilized and unsterilized soils, CO₂ emission mirrored O₂ consumption signifying the presence of several coupled redox reactions transferring electrons from organic C to intermediate acceptors and to O₂. This supports the idea that non-cellular mineralization results from extracellular oxidative metabolisms catalyzed by soil enzymes and/or abiotic catalysts. Our findings also show that non-cellular SOC mineralization is ubiquitous and contributes to 24% of soil respiration on average. Cellular and non-cellular SOC mineralization are positively linked but the contribution of non-cellular processes to soil CO₂ emissions increases with dissolved organic carbon concentration.

24562. 题目: Abatement of 2,4-D by H₂O₂ solar photolysis and solar photo-Fenton-like process with minute Fe(III) concentrations
文章编号: N18080401
期刊: Water Research
作者: Anna Serra-Clusellas, Laura De Angelis, Chung-Ho Lin, Phuc Vo, Mohamed Bayati, Lloyd Sumner, Zhentian Lei, Nathalia B. Amaral, Liliana M. Bertini, Jose Mazza, Luis R. Pizzio, Jorge D. Stripeikis, Julián A. Rengifo-Herrera, María M. Fidalgo de Cortalezzi
更新时间: 2018-08-04
摘要: The Photo-Fenton-like (PF-like) process with minute Fe(III) concentrations and the Hydrogen Peroxide Photolysis (HPP), using Xe-lamp or solar light as sources of irradiation, were efficiently applied to eliminate the herbicide 2,4-D from water. PF-like experiments concerning ferric and H₂O₂ concentrations of 0.6 mg L⁻¹ and 20 mg L⁻¹ respectively, using Xenon lamps (Xe-lamps) as a source of irradiation and 2,4-D concentrations of 10 mg L⁻¹ at pH 3.6, exhibited complete 2,4-D degradation and 77% dissolved organic carbon (DOC) removal after 30 min and 6 h of irradiation respectively whereas HPP (in absence of ferric ions) experiments showed a 2,4-D reduction and DOC removal of 90% and 7% respectively after 6 h of irradiation. At pH 7.0, HPP process achieved a 2,4-D abatement of approximately 75% and a DOC removal of 4% after 6 h. PF-like exhibited slightly improved 2,4-D and DOC removals (80% and 12% respectively) after the same irradiation time probably due to the low pH reduction (from 7.0 to 5.6). Several chlorinated-aromatic intermediates were identified by HPLC-MS. These by-products were efficiently removed by PF at pH 3.6, whereas at neutral PF-like and acid or neutral HPP, they were not efficiently degraded. With natural solar light irradiation, 10 and 1 mg L⁻¹ of 2,4-D were abated using minor H₂O₂ concentrations (3, 6, 10 and 20 mg L⁻¹) and iron at 0.6 mg L⁻¹ in Milli-Q water. Similar results to Xe-lamp experiments were obtained, where solar UV-B + A light H₂O₂ photolysis (HPSP) and solar photo-Fenton-like (SPF-like) played an important role and even at low H₂O₂ and ferric concentrations of 3 and 0.6 mg L⁻¹ respectively, 2,4-D was efficiently removed at pH 3.6. Simulated surface water at pH 3.6 containing 1 mg L−1 2,4-D, 20 mg L⁻¹ H₂O₂ and 0.6 mg L⁻¹ Fe(III) under natural sunlight irradiation efficiently removed the herbicide and its main metabolite 2,4-DCP after 30 min of treatment while at neutral pH, 40% of herbicide degradation was achieved. In the case of very low iron concentrations (0.05 mg L⁻¹) at acid pH, 150 min of solar treatment was required to remove 2,4-D.
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24563. 题目: Singlet Oxygen Phosphorescence as a Probe for Triplet-State Dissolved Organic Matter Reactivity
文章编号: N18080323
期刊: Environmental Science & Technology
作者: Paul R. Erickson, Kyle J. Moor, Jeffrey J. Werner, Douglas E. Latch, William A. Arnold, Kristopher McNeill
更新时间: 2018-08-03
摘要: Triplet-state chromophoric dissolved organic matter (³CDOM*) plays an important role in aquatic photochemistry, yet much remains unknown about the reactivity of these intermediates. To better understand the kinetic behavior and reactivity of ³CDOM*, we have developed an indirect observation method based on monitoring time-resolved singlet oxygen (¹O₂) phosphorescence kinetics. The underpinning principle of our approach relies on the fact that O₂ quenches almost all triplets with near diffusion limited rate constants, resulting in the formation of ¹O₂, which is kinetically linked to the precursors. A kinetic model relating ¹O₂ phosphorescence kinetics to triplet excited states produced from isolated humic substances and in whole natural-water samples (hereafter referred to as ³CDOM*) was developed and used to determine rate constants governing ³CDOM* natural lifetimes and quenching by oxygen and 2,4,6-trimethylphenol (TMP), a common triplet probe molecule. ³CDOM* was found to exhibit smaller O₂ and TMP quenching rate constants, ∼9 × 10⁸ and ∼8 × 10⁸ M^–1 s^–1, respectively, compared with model sensitizers, such as aromatic ketones. Findings from this report shed light on the fundamental photochemical properties of CDOM in organic matter isolates and whole waters and will help refine photochemical models to more accurately predict pollutant fate in the environment.
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24564. 题目: Microbial biomass, metabolic functional diversity, and activity are affected differently by tillage disturbance and maize planting in a typical karst calcareous soil
文章编号: N18080322
期刊: Journal of Soils and Sediments
作者: Dan Xiao, Shuangshuang Xiao, Yingying Ye, Wei Zhang, Xunyang He, Kelin Wang
更新时间: 2018-08-03
摘要: Purpose: Cultivation can affect soil microbial activities, with consequences for microorganisms that metabolize soil organic carbon and release CO₂ to the atmosphere. Nevertheless, there is limited understanding of the short-term effects that tillage disturbance, maize planting, or their interactions exert on microbial biomass and metabolic function in a typical karst calcareous soil. A 1-year simulation experiment quantified the impacts of tillage disturbance and maize planting on soil microorganisms. Materials and methods: Four treatments (2 × 2 m plot size), comprising conventional tillage with (CTM) and without maize (CT), and non-tillage with (NTM) and without (NT) maize, were conducted. Microbial biomass carbon (MBC), carbon metabolic function (Biolog profiles), CO₂ flux, soil organic carbon (SOC), and dissolved organic carbon (DOC) were measured after 1-year tillage disturbance and maize planting. Results and discussion: DOC was significantly lower in CTM, NTM, and CT than in NT, but SOC was slightly higher in NTM than in CTM and NT. Annual cumulative CO₂ fluxes were significantly higher in CTM and NTM than in CT, which in turn was significantly higher than NT. Principal component analysis (PCA) suggests microbial community catabolic function differs in all treatments. CT showed significantly decreased MBC compared with NT, but significantly increased microbial metabolic activity and Simpson index (D). Compared with NT, NTM showed significantly increased microorganism metabolic activity, Shannon index (H), and D, but no significant difference in MBC. The interactions between maize planting and tillage disturbance had no significant effect on MBC or metabolic function diversity. Conclusions: Microbial biomass appears sensitive to tillage disturbance, while microbial metabolic activity is sensitive to maize planting. Maize planting with no tillage would increase CO₂ emissions through enhanced microbial activity, but, at the same time, mitigate SOC loss due to an increase in C input by crop residues and roots left in the soil.

24565. 题目: Nitrogen cycling and origin of ammonium during infiltration of treated wastewater for managed aquifer recharge
文章编号: N18080321
期刊: Applied Geochemistry
作者: Matthew Silver, Kay Knöller, Johanna Schlögl, Christine Kübeck, Christoph Schüth
更新时间: 2018-08-03
摘要: As more regions in the world look to replenish depleted aquifers, treated wastewater (TWW) is increasingly infiltrated in managed aquifer recharge (MAR) schemes. While MAR is a promising emerging technology, it also has the potential to generate pollutants along the infiltration flow path. In this study, we infiltrated treated wastewater through an organic-rich soil in column experiments operated with wetting and drying cycles. Ammonium, which was present only in trace concentrations in the TWW, increased in concentration with depth and exceeded the EU Water Framework Directive limit of 0.5 mg/L for up to a year, depending on the sampling depth. Pore water samples collected at the end of drying periods showed very high nitrate concentrations, indicating nitrification of some of the ammonium. Oxidation reduction potential often exceeded 200 mV during drying periods, showing conditions for nitrification, but dropped to below −100 mV during wetting periods, creating several possible pathways for ammonium production. Potential sources of ammonium are (1) dissolved organic nitrogen in the TWW, (2) nitrate in the TWW, and (3) organic nitrogen in the soil. δ¹⁵N in ammonium in pore water samples (mean 4.7‰) was slightly higher than δ¹⁵N the soil (2.4‰), indicating that the soil was likely the major source but also that nitrate (mean 17.2‰) may have been the source of some of the ammonium. Fractionation of ¹⁵N in nitrate as well as high concentrations of acetate (a labile organic carbon source) also indicate that dissimilatory nitrate reduction to ammonium may have formed some of the NH₄⁺.
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24566. 题目: Soil quality assessment in Yellow River Delta: Establishing a minimum data set and fuzzy logic model
文章编号: N18080320
期刊: Geoderma
作者: Chunsheng Wu, Gaohuan Liu, Chong Huang, Qingsheng Liu
更新时间: 2018-08-03
摘要: The Yellow River Delta has abundant land resources, but the land exhibits heavy degeneration because of long-term exposure to harsh natural conditions and improper human activities, and the soil quality is poor in some areas. All these factors have adversely affected agricultural development and ecological protection in the Yellow River Delta. This study selected multiple physical and chemical indicators and used principal component analysis (PCA) to construct a minimum data set (MDS) to determine a comprehensive set of indicators for assessing soil quality in the Yellow River Delta. Moreover, a fuzzy logic model was used to assess soil quality and analyze the spatial distribution of the primary land use types in different soil quality grades. The results indicate that the MDS includes six soil indicators: total nitrogen (TN), available phosphorus (AP), available potassium (AK), soil organic matter (SOM), soil salinity (SS) and pH. According to the spatial distribution maps of the indicators, SS gradually declined from the coast to the inland areas, while TN and AP had opposite characteristics. AK and pH were evenly distributed around the study area, and SOM was highest in the center and gradually declined toward the edge of the study area. The soil quality was higher in inland areas than in coastal areas, and most of the study area was classified as grade III. Most of the farmland, forest, and garden plots were distributed in high-grade soil levels, but some of these plots were distributed in areas classified as grades V or VI. Many areas with high soil quality were unused, which indicated that the land resources of the study area should be planned reasonably.

24567. 题目: Ultra-high resolution mass spectrometry of physical speciation patterns of organic matter in fire-affected soils
文章编号: N18080319
期刊: Journal of Environmental Management
作者: Nicasio T. Jiménez-Morillo, José A. González-Pérez, Gonzalo Almendros, José M. De la Rosa, Derek C. Waggoner, Antonio Jordán, Lorena M. Zavala, Francisco J. González-Vila, Patrick G. Hatcher
更新时间: 2018-08-03
摘要: Fire is one of the most important modulating factors of the environment and the forest inducing chemical and biological changes on the most reactive soil component, the soil organic matter (SOM). Assuming the complex composition of the SOM, we used an ultra-high resolution mass spectrometry analysis technique to assess the chemical composition and fire-induced alterations in soil particle size fractions (coarse and fine) from a sandy soil in a Mediterranean oak forest at Doñana National Park (Southwest Spain). Electrospray ionization-Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICRMS) showed that the coarse fraction of soils not affected by fires consisted mainly of polyphenolic compounds consistent with little-transformed SOM and fresh biomass, whereas the fine fraction was enriched in protein and lipid like homologues suggesting microbially reworked SOM. In fire-affected SOM, the coarse fraction contained a high proportion of aromatic compounds, consistent with inputs of charred litter or in situ chemical transformation of the SOM. Analysis of the fine fraction revealed two differentiated chemical families pointing to the existence of two carbon pools; a native microbial-derived moiety composed of lipids and polypeptide compounds, and a secondary, pyrogenic or thermally-altered moiety rich in aromatic compounds. This work represents the first application of ultra-high resolution mass spectrometry to study the chemical composition of SOM in different particle size fractions.
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24568. 题目: Insights into the roles of recently developed coagulants as pretreatment to remove effluent organic matter for membrane fouling mitigation
文章编号: N18080318
期刊: Journal of Membrane Science
作者: Quang Viet Ly, Long D. Nghiem, Jinwoo Cho, Jin Hur
更新时间: 2018-08-03
摘要: Membrane fouling by dissolved organic matter (EfOM) in secondary treated effluent is a problematic and inevitable issue during wastewater reclamation using low pressure membrane filtration. This study evaluates the performance of coagulation/flocculation (C/F) using two recently developed coagulants (namely TiCl₄ and ZrCl₄) in comparison to conventional alum (i.e. Al₂(SO₄)₃) as pretreatment to remove EfOM for subsequent ultrafiltration (UF) membrane fouling mitigation. At the optimal dosage, TiCl₄-based C/F pretreatment showed the greatest performance in membrane fouling mitigation, followed by ZrCl₄ and then alum. The underlying mechanisms were well explained by classical fouling models and the extended Derjaguin-Landau-Verwey-Overbeek (xDLVO) theory, highlighting a dominant role of standard blocking in the fouling potential of the C/F treated EfOM. The interfacial free energy of cohesion and adhesion showed that C/F pretreatment using TiCl₄ and ZrCl₄ as coagulant can lower the binding affinity between EfOM molecules and between EfOM molecules and membrane surface, ultimately reduce membrane fouling. The results of size exclusion chromatography (SEC) and fluorescence excitation emission matrix- parallel factor analysis (EEM-PARAFAC) also supported the classical fouling mechanisms, providing additional insights into the potential roles of chemical interactions in the preferential removal of certain organic substances by C/F pretreatment and the chemical composition of subsequent membrane foulants. Protein-like components were highly associated with reversible fouling after the C/F, while the reversibility of humic-like substances was enhanced upon C/F pretreatment. After C/F pretreatment, small sized EfOM molecules became the dominant fraction responsible for UF membrane fouling.
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24569. 题目: High efficiency and rapid degradation of bisphenol A by the synergy between adsorption and oxidization on the MnO₂@nano hollow carbon sphere
文章编号: N18080317
期刊: Journal of Hazardous Materials
作者: Yimei Zhang, Fei Wang, Ping Ou, Hao Zhu, Yuxian Lai, Yalong Zhao, Weilin Shi, Zhuang Chen, Shuai Li, Tong Wang
更新时间: 2018-08-03
摘要: In this research, a novel efficiency MnO₂@Nano hollow carbon sphere (MnO₂@NHCS) nanocomposite was prepared by one-pot hydrothermal reaction with KMnO₄ solution. The adsorption and oxidization performance of MnO₂@NHCS were assessed by degradation of bisphenol A (BPA) at different conditions. The effect of dosage of MnO₂@NHCS, pH, initial concentration of BPA, temperature and humic acid were investigated systematically. Moreover, the characterizations of MnO₂@NHCS were measured by a series of techniques, such as XRD, FESEM, HRTEM, TGA and XPS. Notably, hollow structure of nano carbon sphere was still retained with uniform MnO₂ nanosheets covered. The results show that the removal rate of BPA was 95.3% within 10 min and BPA can be almost decomposed in 30 min under the optimal conditions. Additionally, the MnO₂@NHCS remained stable and had a high regeneration efficiency (more than 85%) after 3 cycles (360 minutes). The reaction intermediates/products of oxidation of BPA were analyzed and the possible degradation pathways of BPA were proposed. These research results demonstrate that the MnO₂@NHCS is a fleet and efficient material for BPA degradation in aqueous environment.
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24570. 题目: Enhancement of ligninolytic enzymes production and decolourising activity in Leptosphaerulina sp. by co–cultivation with Trichoderma viride and Aspergillus terreus
文章编号: N18080316
期刊: Science of The Total Environment
作者: Ledys S. Copete-Pertuz, Felipe Alandete-Novoa, Jersson Plácido, Guillermo A. Correa-Londoño, Amanda L. Mora-Martínez
更新时间: 2018-08-03
摘要: This work investigated fungal co–culture as inducer of ligninolytic enzymes and decolourising activity in the Colombian strain Leptosphaerulina sp., an ascomycete white-rot fungus isolated from lignocellulosic material. Aspergillus niger, Aspergillus fumigatus, Aspergillus terreus, Trichoderma viride, Fusarium sp. and Penicillium chrysogenum were tested as Leptosphaerulina sp. inducers. The best fungal combinations in terms of enzyme production, fungal growth and decolourising activity were selected from solid media experiments. Response surface methodology (RSM) was utilised to optimise enzyme production and decolourising activity in liquid media. Solid media assays evidenced T. viride and A. terreus as the best Leptosphaerulina sp. inducers. The RSM identified a triple co–culture inoculated with T. viride (1000 μL) and A. terreus (1000 μL) into a 7–day culture of Leptosphaerulina sp. as the best treatment. This triple combination significantly improved ligninolytic enzymes production and Reactive Black 5 dye removal when compared to the Leptosphaerulina sp. monoculture and previously used chemical inducers. These results demonstrated the potential of fungal co–culture as an environmentally–friendly method to enhance Leptosphaerulina sp. enzymes production and decolourising activity.
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24571. 题目: Use of biogas digestates obtained by anaerobic digestion and co-digestion as fertilizers: Characterization, soil biological activity and growth dynamic of Lactuca sativa L.
文章编号: N18080315
期刊: Science of The Total Environment
作者: Gastón Alejandro Iocoli, María Celina Zabaloy, Gonzalo Pasdevicelli, Marisa Anahí Gómez
更新时间: 2018-08-03
摘要: Agro-industrial systems provide large quantities of organic wastes that could imply an important environmental risk. While manures can be easily treated by anaerobic digestion, horticultural fruit wastes generally cannot be processed alone and should be treated by co-digestion. To use organic wastes as fertilizers is fundamental to improve understanding of their impact on soil-plant systems. In this research, cattle manure, poultry litter, pig slurry and onion waste were collected. Animal manures were studied without treatment, treated by anaerobic digestion alone and in co-digestion with onion wastes. To study their effect on soil-plant systems, chemical and spectroscopic characterization of manures and their transformed products were combined with soil biological activity and growth dynamic of lettuce following wastes incorporation to the soil. Anaerobic digestion decreased the C/N ratio, whilst there was an increase in NH₄⁺-N/N ratio and short-chain organic acids. The magnitude of these changes varied depending on the type of organic matter present in each material and the incorporation of onion wastes intensified them. However, the digestates presented similar structural characteristics to each other, independently of the material of origin. Digestate soil application produced a fast and short microbial stimulation (18–34 and 7–11 mg CO₂ during the first 6 h, digestates vs. rest of treatments). The digestate dosage should be done according to the content of NH₄⁺-N given that the vegetal growth is related to it. Soils amended with digestates showed less CO₂ emission than soils amended with manures improving overall C balance.
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24572. 题目: Tree species affects the concentration of total mercury (Hg) in forest soils: Evidence from a forest soil inventory in Poland
文章编号: N18080314
期刊: Science of The Total Environment
作者: Piotr Gruba, Jarosław Socha, Marcin Pietrzykowski, Daryna Pasychnyk
更新时间: 2018-08-03
摘要: This study was performed to test the hypothesis that tree species significantly affects mercury (Hg) sequestration in forest soils. We analyzed the effect of seven dominant tree species (Scots pine, black alder, Norway spruce, silver birch, deciduous oak, silver fir, and European beech on the concentrations and pools of Hg in a range of forest soils in Poland. We set up 277 sample plots representing dominant tree species in Poland. Soil samples were taken and analyzed for total Hg content, soil texture, and soil C and nitrogen (N) content. Concentrations of total Hg in forest soil (organic and mineral horizons) varied by several orders of magnitude as a result of natural variations in organic matter, sand content, and altitude. Spatial analysis revealed that maximum concentrations (mg kg⁻¹) and stocks (mg m⁻²) of Hg were related to mountain stands at higher elevations with loamy soils and greater accumulation of soil organic matter. The stocks of Hg in the investigated soil profiles increased in the order of: pine (12 mg m⁻²) ≈ birch (15 mg m⁻²) < oak (21 mg m⁻²) ≈ alder (24 mg m⁻²) < beech (45 mg m⁻²) ≈ spruce (50 mg m⁻²) < fir (66 mg m⁻²). Simple analysis of variance suggested an important effect of dominant tree species on Hg concentrations and stocks in entire soil profiles, but multiple regression analysis showed that dominant tree species had a significant effect on accumulation of Hg in soil, but only in the organic horizon; in mineral soil the Hg was content was related to C content, soil texture and altitude. The organic horizon had greater accumulation of Hg under coniferous tree species (Scots pine, silver fir and Norway spruce) and European beech when compared with deciduous oak, black alder, and silver birch.
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24573. 题目: Spatial distribution of pharmaceuticals in conventional wastewater treatment plant with Sludge Treatment Reed Beds technology
文章编号: N18080313
期刊: Science of The Total Environment
作者: Katarzyna Kołecka, Magdalena Gajewska, Piotr Stepnowski, Magda Caban
更新时间: 2018-08-03
摘要: Pharmaceutical residues are an emerging environmental problem. It is strongly confirmed that pharmaceuticals are present in soils and environmental waters (surface, marine and even groundwater), and that wastewater treatment plant (WWTP) effluents are the main source of pharmaceuticals in the watershed. The aim of this study was to recognize the spatial distribution and seasonal changes of selected pharmaceuticals in conventional WWTP with Sludge Treatment Reed Beds (STRBs) technology used for dewatering and stabilization of sewage sludge, because these systems have never been studied in terms of pharmaceuticals distribution or removal potential.
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24574. 题目: Responses of labile soil organic carbon and nitrogen pools to long-term prescribed burning regimes in a wet sclerophyll forest of southeast Queensland, Australia
文章编号: N18080312
期刊: Science of The Total Environment
作者: Bushra Muqaddas, Tom Lewis, Maryam Esfandbod, Chengrong Chen
更新时间: 2018-08-03
摘要: Soil labile organic carbon (C) and nitrogen (N) pools play a central role in nutrient cycling, while fire is a key driver of biogeochemical cycle, shaping ecosystem structure and functioning. However, how soil labile organic C and N responds to the long-term repeated prescribed fire is largely unknown. In this study, a prescribed fire field experiment in a wet sclerophyll forest established in 1972 in southeast Queensland was used to evaluate the long-term impacts of different fire frequency regimes on labile organic C and N measured by different extraction methods. The fire frequency regimes included long unburnt (NB), burnt every two years (2yrB) and burnt every four years (4yrB). Results revealed that the 2yrB treatment had significantly lower C and N concentrations in hot water and K₂SO₄ extracts and in density fractions (LF_D<2.3 and HF_D>1.6) compared with the NB treatment. Concentrations of carbohydrate-C in hot water extracts and acid soluble and insoluble organic matter-C in cold-water extracts followed a similar trend. The maximum reduction was observed for carbohydrate‑C (72%) and the hot water extractable N (54%) in the 2yrB treatment compared with the NB treatment, showing these parameters are most sensitive indicators. However, there was no significant difference in most of the above parameters between the 4yrB and the NB treatments, indicating that less frequent fire (4yrB) allows the ecosystem to have sufficient time to recover from fire disturbance and may be a sustainable practice for fire management in this wet sclerophyll forest ecosystem.
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24575. 题目: Optimization and mechanism studies on cell disruption and phosphorus recovery from microalgae with magnesium modified hydrochar in assisted hydrothermal system
文章编号: N18080311
期刊: Science of The Total Environment
作者: Yaxin Deng, Tao Zhang, Brajendra K. Sharma, Haiyu Nie
更新时间: 2018-08-03
摘要: Considering the phosphorus (P) reserve state and its value, recovery of P from microalgae has become a popular topic. In this study, an integrated system of a hydrothermal process for microalgae cell disruption to release P and magnesium modified hydrochar adsorption to capture P was set up. Emission scanning electron microscopy with Energy Dispersive X-ray spectroscopy and Three-Dimensional Excitation Emission matrix spectroscopy with parallel factor analysis were applied to evaluate the P release process from microalgae and found the optimal breaking-wall condition (P release 90.5%, hydrothermal digestion mixture of H₂O₂ and NaOH at 348 K). Parallel factor analysis showed there was a close relationship between P and humic-like substance. Hydrochar loaded with magnesium exhibited a strong affinity for P, with maximum capacity 89.61 mg/g at 318 K. The P adsorption fitted pseudo-second-order kinetic and Langmuir models. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy were applied to reveal the mechanism of hydrochar modification and adsorption. It showed that Mg is loaded on the surface of hydrochar by electrostatic attraction and electron transfer with the carboxylic acid. P absorption was reached through anion exchange.
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24576. 题目: Direct measurement of dissolved dinitrogen to refine reactive modelling of denitrification in agricultural soils
文章编号: N18080310
期刊: Science of The Total Environment
作者: Micòl Mastrocicco, Nicolò Colombani, Giuseppe Castaldelli
更新时间: 2018-08-03
摘要: Nitrogen fertilizers used in agriculture often cause nitrate leaching towards shallow groundwater, especially in lowland areas where soil permeability, ploughing, clay content, and the flat topography minimizes surface runoff. The introduction of good agricultural practices to reduce the nitrate amount entering the groundwater system is crucial to ameliorate the kinetic control on nitrate denitrification capacity. With this aim, a series of anaerobic mesocosms, consisting of loamy and clay soils and nitrate rich water, were modelled using acetate and natural organic matter as electron donors. Acetate was chosen because it is the main intermediate in many biodegradation pathways of organic compounds, and hence it is a suitable carbon source for denitrification. To account for the spatial variability of soil parameters, the experiments were performed in triplicates. The geochemical code PHREEQC(3) was used to simulate kinetic denitrification, and equilibrium reactions of gas and mineral phases. The reactive modelling results highlighted a rapid acetate and nitrate degradation rate, a rapid production of dissolved inorganic carbon and dinitrogen, and a steady concentration of dissolved iron and sulphate, suggesting that the main pathway of nitrate attenuation is through denitrification; concomitantly excluding the occurrence of other processes leading to nitrate consumption. In the absence of acetate, the loamy soil, poor of natural organic matter, did not allow to complete the denitrification process.
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24577. 题目: Altitude and decomposition stage rather than litter origin structure soil microarthropod communities in tropical montane rainforests
文章编号: N18080309
期刊: Soil Biology and Biochemistry
作者: Franca Marian, Dorothee Sandmann, Valentyna Krashevska, Mark Maraun, Stefan Scheu
更新时间: 2018-08-03
摘要: Microarthropods impact organic matter turnover and nutrient cycling via processing of organic matter entering the soil as litter and root exudates. Variations in the structure of soil microarthropod communities are due to both biotic and abiotic factors such as local climatic conditions and litter quality. However, in particular in tropical ecosystems the relative importance of these factors for structuring soil microarthropod communities are little understood. We investigated variations in the structure of soil microarthropod communities in leaf and root litter from three altitudes exposed in three tropical montane rainforests at different altitude in southern Ecuador for three years. Leaf litter from three abundant tree species and roots of different diameter were collected from three sites at different altitude (ca. 1000, 2000, 3000 m). Litter and roots were placed in litterbags at the three altitudes, and after 6, 12, 24 and 36 months soil microarthropods in the litterbags were analysed. Density of Acari and Collembola, and diversity of Oribatida decreased with increasing altitude and varied with the degree the litter was decomposed rather than with litter origin and therefore quality of the litter material. Densities fluctuated during litter decomposition generally being lowest after 24 months but higher after 36 months. Species composition of Oribatida varied strongly with altitude; only few species overlapped between altitudes. The percentage of parthenogenetic Oribatida species decreased with increasing altitude. The results suggest that the origin and therefore quality of litter material is of little importance as driving factor for the composition of microarthropod communities of tropical montane rainforests. Factors changing between rainforest sites at different altitude, as well as decomposition stage of litter and associated changes in the microbial community are much more important.

24578. 题目: The Impact of Carbon Source as Electron Donor on Composition and Concentration of Dissolved Organic Nitrogen in Biosorption-Activated Media for Stormwater and Groundwater Co-Treatment
文章编号: N18080308
期刊: Environmental Science & Technology
作者: Ni-Bin Chang, Dan Wen, Amy M. McKenna, Martin P. Wanielista
更新时间: 2018-08-03
摘要: Eutrophication has been a long-term issue in aquatic environments, where dissolved organic nitrogen (DON) recalcitrance is important. Bioavailable nitrogen qualification and quantification for effluents from stormwater and wastewater are always a challenge. The information in this study deepens the understanding of the interactions between carbon addition and DON decomposition through linear-ditch best management practices for stormwater and groundwater cotreatment. By running a laboratory-scale column study for nitrogen removal using green sorption media, the variation in composition and concentration of DON can be further linked to the population dynamics of microbial species that dominate the nitrification and denitrification processes. With the varying levels of influent total nitrogen concentration, the efficacy of nitrogen removal via biosorption activated media may be realized at the molecular level with ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry.
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24579. 题目: Soil fauna as bioindicators of organic matter export in temperate forests
文章编号: N18080307
期刊: Forest Ecology and Management
作者: François Elie, Lucie Vincenot, Thierry Berthe, Edouard Quibel, Bernhard Zeller, Laurent Saint-André, Matthieu Normand, Matthieu Chauvat, Michaël Aubert
更新时间: 2018-08-03
摘要: Numerous studies predict a short-term important decrease in fossil resources and stress the need to develop alternative renewable energies, thus European countries aim at increasing biomass production for energetic purposes. One such source of bioenergy could be obtained from forest biomass pools by exporting logging residues, yet this practice would have strong impacts on forest ecosystems (e.g. disturbance of soil biodiversity and chemical properties). Most studies on biomass removal effects focused on boreal forests but responses in temperate forests are still scarcely studied. Soil macrofauna is involved in forest ecosystem functioning through numerous chemical, physical and biological processes and multiple interactions with other organisms. A disturbance of the soil macrofauna community can thus lead to a response of the forest ecosystem as a whole. Experimental plots were set up in 6 northern France forests (either dominated by oak or beech), with a treatment corresponding to Whole Tree Harvesting (WTH) practices compared to control, in order to characterize the response of soil macrofaunal communities to organic matter (OM) export. Our study showed that OM export leads to a short-term loss of abundance in macrofaunal communities in temperate deciduous forest soils that can also lead to an alteration of soil OM cycle, and revealed that the breadth of this negative impact is modulated by tree species and faunal trophic groups. Furthermore, some results of community responses were directly applicable to forest management as marked responses of several taxa revealed four bioindicators of OM disturbance. Therefore, the level of disturbance related to new forest management practices, such as WTH to increase forest biofuel yields, (i) could be characterized by surveying either total soil macrofauna or using tools such as bioindicator taxa and (ii) should be assessed regarding tree stand identity.
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24580. 题目: Site-specific assessment of spatial and temporal variability of sugarcane yield related to soil attributes
文章编号: N18080306
期刊: Geoderma
作者: Guilherme M. Sanches, Paulo S. Graziano Magalhães, Henrique C. Junqueira Franco
更新时间: 2018-08-03
摘要: The adoption of information technology (IT) and precision agriculture (PA) has converted agricultural fields into data sources. However, the transformation of data into knowledge for decision making remains a major challenge. In the Brazilian sugarcane industry, the current use of PA technology is very far from its full potential for site-specific management, mainly because yields are not temporally or spatially monitored. The objective of the present study was to investigate the relationship between the physical and chemical properties of soils and sugarcane yield, thereby identifying the soil parameters that determine the final productivity of the field. Two sugarcane fields were monitored from 2011 to 2014. During the crop season, soil samples and yield data were collected annually. A random forest algorithm was applied to investigate the influence of different soil attributes on yield using data that were collected spatially over the study period. The results showed that the amount of available soil organic matter (OM), clay content and cation exchange capacity (CEC) are important factors impacting sugarcane yield variation. Furthermore, it was found that the temporal variability in yield is caused mainly by the variability in soil pH over the study period. The results indicated that when OM increased over time, there was greater phosphorus availability. Large volumes of spatial and temporal data, together with data mining techniques, allowed the extraction of knowledge and the creation of specific management zones in the field to support the decision-making process for producers.