论文检索

总访问量：2735951次

总访客量：122955人

所有论文

25901. 题目: Improved methane production from waste activated sludge by combining free ammonia with heat pretreatment: Performance, mechanisms and applications
文章编号: N18080410
期刊: Bioresource Technology
作者: Xuran Liu, Qiuxiang Xu, Dongbo Wang, Jianwei Zhao, Yanxin Wu, Yiwen Liu, Bing-Jie Ni, Qilin Wang, Guangming Zeng, Xiaoming Li, Qi Yang
更新时间: 2018-08-04
摘要: Anaerobic digestion of waste activated sludge (WAS) is often limited by low hydrolysis efficiencies and poor methane potentials. This work presents a novel pretreatment technology for WAS anaerobic digestion, i.e., combining free ammonia with heat pretreatment (CFHP). Experimental results showed that compared with control, solo free ammonia (135.4 mg NH₃-N/L) and solo heat (70 °C) pretreatment, the combined free ammonia and heat (135.4 mg NH₃-N/L with 70 °C) obtained 52.2%, 25.5% and 30.2% faster in hydrolysis rate and 25.2%, 17.9% and 16.5% higher in biochemical methane potential, respectively. Mechanism investigations showed that the combined pretreatment not only largely facilitated the disintegration of WAS but also increased the proportion of biodegradable organic matters, thereby providing better contract between biodegradable organics and the anaerobic microbes for methane production. Considering its effectiveness and renewability, the combined pretreatment is an attractive technology for the application in real-world situations.
图文摘要:

25902. 题目: A microscopic simulation of particle flux in ocean waters: application to radioactive pair disequilibrium
文章编号: N18080409
期刊: Geochimica et Cosmochimica Acta
作者: F. De Soto, E. Ceballos-Romero, M. Villa-Alfageme
更新时间: 2018-08-04
摘要: The biological carbon pump, a fundamental component of the global carbon cycle, is a mechanism comprised of biological processes that transfer large amounts of organic carbon from the upper ocean to the ocean’s interior. It sequesters CO₂ for weeks to hundreds or even millions of years through the sinking of a complex mix of biogeo-chemical material. As particles sink the flux of particulate organic carbon attenuates and only a fraction of the flux reaches the ocean’s depth. Quantifying the attenuation of sinking particulate carbon flux is key to assess the amount of carbon sequestered in the twilight zone. Current knowledge of the particle flux attenuation relies on a reduced number of direct measurements, usually fitted to a power law, that tries to describe the result of a large variety of biological, physical and chemical processes involved. We present a stochastic simulation for particle production, sinking and degradation in the oceans that includes most of the essential ingredients to ultimately describe the sinking carbon flux in the ocean and where all the complex biogeochemical behavior is captured by macroscopic parameters. The algorithm proposed interprets these phenomena probabilistically and is an ideal framework to describe the observed patterns of particle flux attenuation in depth. Particles are randomly produced and degraded with depth-dependent functions, which reproduces the variability of these processes in nature. Hence, the simulation proposed provides a suitable approach to analyse sinking carbon when different particle sizes or speeds are used. Furthermore, production and degradation phenomena are time-dependent, this way their seasonal evolution can be additionally explored and the simulation results in an ideal test-bed for the assessment of both steady and non-steady state situations. In addition, the theoretical formulation proposed provides a simple frame to include particle-metals interactions through adsorption and desorption processes. In this paper we relate typical parametrizations of the flux attenuation curve to their corresponding degradation rate and propose an alternative parametrization to model the flux degradation function which is negligible at very large depths, therefore producing a constant residual flux, and remains finite in the euphotic zone. This degradation function is implemented in the simulation and applied to estimate the scavenging of the naturally occurring radioisotopes ²³⁴Th and ²¹⁰Po. We use the results to estimate effective adsorption and desorption rate constants for both isotopes. We found that the degradation rate, rather than the half-life, controls the depth at which the parent and daughter reach equilibrium. Thus, this depth is ruled by a combination of the degradation rate and the particle sinking velocity.

25903. 题目: Biomarker signatures of the iconic Glossopteris plant
文章编号: N18080408
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Anuradha Tewari, Ashalata D'Rozario, Sharmila Bhattacharya, Ahinsuk Barua, Meghma Bera, Subir Bera, Suryendu Dutta
更新时间: 2018-08-04
摘要: Glossopteris is the quintessential marker plant that dominated the forests of the Southern Hemisphere continents during the Permian before their abrupt extinction at the close of the Palaeozoic. Fossilized leaf and stem remains of Glossopteris plants, collected from the Permian succession of eastern India, were analysed to recognize the molecular signatures of solvent-extractable and non-extractable organic matter. Lipid-derived aliphatic and aromatic biomarkers were studied using GC–MS and GC × GC-TOFMS, while tetramethylammonium hydroxide (TMAH) thermochemolysis with GC–MS and GC × GC-TOFMS was used to reveal lignin precursors. The thermal maturity indices indicate low thermal rank for both samples. The presence of aromatic diterpanes in the leaf extract suggests that the Glossopteris plant was able to biosynthesize abietic acid and related plant terpenoids. The thermochemolysis products (thermochemolysates) of the samples contain monomethoxy-, and dimethoxybenzene derivatives produced from p‑hydroxyphenyl and guaiacyl units of lignin, respectively, which are the main constituents of extant gymnosperm lignin. The thermochemolysates indicate that lignin biosynthesis had evolved in Glossopteris.

25904. 题目: Interrelationship of biomass yield, carbon input, aggregation, carbon pools and its sequestration in Vertisols under long-term sorghum-wheat cropping system in semi-arid tropics
文章编号: N18080407
期刊: Soil and Tillage Research
作者: Ashim Datta, Biswapati Mandal, Shrikant Badole, Krishna Chaitanya A., S.P. Majumder, Dhaneshwar Padhan, Nirmalendu Basak, Arijit Barman, Ritesh Kundu, W.N. Narkhede
更新时间: 2018-08-04
摘要: We investigated dynamics of soil organic carbon (SOC) i.e. total soil organic carbon (TOC), oxidisable organic carbon (OC) and its different pools viz. very labile (C_VL), labile (C_L), less labile (C_LL) and non-labile (C_NL), and various sized aggregate associated carbon (AAC) and also its sequestration along depth (0-0.15, 0.15-0.30, and 0.30 -0.45 m) in a typical Vertisols under hot semi-arid agro-climatic conditions. Such dynamics were studied under different soil management practices viz., control, NPK (100% recommended doses of N, P and K fertilizers, RDF), NPK + FYM (50% N and whole of the RDF and 50% N through FYM) and fallow using a 28 year old long-term experiment with sorghum (Sorghum bicolour L.) – wheat (Triticum aestivum L.) cropping system. On average, a higher proportion (70% of TOC) of SOC was found in passive pool (less labile + non labile) than active one (very labile + labile) throughout the profile. The proportion of active pool was, however, higher under balanced (NPK) and integrated nutrient management practices (NPK + FYM) over the others followed. Long-term intensive cropping with NPK (15.1%) and NPK + FYM (22%) caused a net enrichment in SOC stock over the control. To offset the loss of C and maintain the SOC level, a critical amount of 0.96 Mg C ha⁻¹yr⁻¹ was needed to be incorporated into the soil. Out of the total water stable aggregates (WSA), mesoaggregates (0.25–2.0 mm) predominated (73.6%) followed by micro (16.4%), and macroaggregates (10.7%) at surface soil. Amount of carbon associated with different sized aggregates had the following trend: mesoaggregate (52.3%) > coarse microaggregate (13.7%)> coarse macroaggregate (13.5%)> (silt + clay) sized aggregate (13.1%)> fine microaggregate (12.2%). Balanced fertilization with organics thus provided not only higher yield but also increased C sequestration in Vertisols even with intensive cropping of sorghum-wheat system under hot semi-arid conditions.

25905. 题目: Microbial diversity associated to the intestinal tract of soil invertebrates
文章编号: N18080406
期刊: Applied Soil Ecology
作者: Dayana da Silva Correia, Samuel Ribeiro Passos, Diogo Neves Proença, Paula Vasconcelos Morais, Gustavo Ribeiro Xavier, Maria Elizabeth Fernandes Correia
更新时间: 2018-08-04
摘要: Interactions between saprophagous invertebrates and microbes are essential for the maintenance and functioning of soil ecosystems, as they directly affect the degradation of organic matter and the nutrient cycle. The intestinal tract of invertebrates is inhabited by a diversity of microbes, and it is closely associated with the food ingested. The aim of this work was to evaluate the profile of prokaryotes associated with the intestinal tract of three invertebrate species. The species of invertebrates Trigoniulus corallinus was collected and incubated in the experiment, after 5 days of incubation we observed the uninduced colonization of two invertebrate species Cubaris murina and Pycnoscelus surinamensis. Therefore, the three species were evaluated in the same way, after 60 days of incubation. The diet supplied comprised different vegetal residues, with distinct carbon/nitrogen compositions. Six treatments were evaluated. After 60 days, five individuals of each species were randomly selected, by removing the posterior third of the intestinal tract. These specimens were next subjected to DNA extraction. The PCR/DGGE analysis was carried out using the 16S rDNA, for the domain Bacteria and the phylum Actinobacteria. DGGE bands were cloned and sequenced using the Bacterial domain. In multivariate analyzes, individuals of the same species after 60 days of incubation, were strongly grouped. These results may be in accordance with the environmental criteria of the host itself, stage of development, phylogeny and diet. Thus, the investigation of the intestinal microbiota, provides relationships between invertebrates and their intestinal bacterial communities. In view of this information, we used the technique of sequencing cloned DGGE bands to quantify the diversity of microorganisms present in the intestinal tract of the studied invertebrates. The phylum Firmicutes, Bacteroidetes, and Proteobacteria were identified by sequencing the cloned bands; Proteobacteria presented the highest number of genera, comprising Enterobacter, Buttiauxella, Serratia, Kluyvera, and Pantoea.

25906. 题目: Iron isotope pathways in the boreal landscape: role of the riparian zone
文章编号: N18080405
期刊: Geochimica et Cosmochimica Acta
作者: Johan Ingri, Sarah Conrad, Fredrik Lidman, Fredrik Nordblad, Emma Engström, Ilia Rodushkin, Don Porcelli
更新时间: 2018-08-04
摘要: Stable Fe isotope compositions have been measured in water samples of the subarctic Kalix River, a first-order stream, and soil water samples from a riparian soil profile adjacent to the first-order stream (Northern Sweden). In the first-order stream, dominated by forest, both the particulate (>0.22µm) and dissolved (< 0.22µm) phase showed negative δ⁵⁶Fe values (relative to IRMM-14) during base flow and meltwater discharge in May (-0.97 to -0.09‰). The Fe isotope composition in the water from the riparian soil profile varied between -0.20 and +0.91‰ with sharp gradients near the groundwater table. A linear correlation between the δ⁵⁶Fe values and the TOC/Fe_bulk ratio was measured during snowmelt in the unfiltered river waters (δ⁵⁶Fe from -0.02 to +0.54‰), suggesting mixing of two Fe components. Two groups of Fe aggregates, with different Fe isotope compositions, are formed in the boreal landscape. We propose that carbon-rich aggregates, Fe(II)(III)-OC, have negative δ⁵⁶Fe values and Fe-oxyhydroxides have positive δ⁵⁶Fe values. A mixture of these two components can explain temporal variations of the Fe isotope composition in the Kalix River. This study suggests that stable Fe isotopes can be used as a tool to track and characterize suspended Fe-organic carbon aggregates during transport from the soil, via first-order streams and rivers, to coastal sediment. Furthermore, the differences in Fe isotope values in the Kalix River and the first-order stream during base flow conditions suggest that the primary Fe sources for river water change throughout the year. This model is combining the Fe isotope composition of first-order streams and rivers to weathering and transport processes in the riparian soil.

25907. 题目: Pathways of inorganic and organic contaminants from land to deep sea: The case study of the Gulf of Cagliari (W Tyrrhenian Sea)
文章编号: N18080404
期刊: Science of The Total Environment
作者: Stella Tamburrino, Salvatore Passaro, Mattia Barsanti, Antonio Schirone, Ivana Delbono, Fabio Conte, Roberta Delfanti, Maria Bonsignore, Marianna Del Core, Serena Gherardi, Mario Sprovieri
更新时间: 2018-08-04
摘要: In continental margins, canyons appear to act as natural conduits of sediments and organic matter from the shelf to deep basins, providing an efficient physical pathway for transport and accumulation of particles with their associated land-produced contaminants. However, these mechanisms have not been yet sufficiently explored by geochemical markers. The continental slope of the south Sardinia has been used as a natural laboratory for investigating mechanisms and times of transfer dynamics of contaminants from land to sea and from shelf to deep sea through an articulated system of submarine canyons. Here, dynamics of contaminants have been investigated in a pilot area of the central Mediterranean basin (Gulf of Cagliari, S Sardinia) where important industrial plants are sited since beginning of the last century. Five sediment cores dated by ²¹⁰Pb and ¹³⁷Cs reveal: i) a complex dynamics of organic and inorganic contaminants from point source areas on land to the deep sea and ii) a crucial role played by canyons and bottom morphology as primary pathway conveying sediments and associated contaminants from sources to very far deep sea environments. In particular, this study provides new integrated tools to properly understand mechanisms of connection between coastal sectors and deep sea. This is challenging mostly in regions where coastal pollution could represent critical threats for larger areas of the Mediterranean Sea.
图文摘要:

25908. 题目: Investigating the use of synthetic humic-like acid as a soil washing treatment for metal contaminated soil
文章编号: N18080403
期刊: Science of The Total Environment
作者: Ting Yang, Mark E. Hodson
更新时间: 2018-08-04
摘要: Humic acid can effectively bind several metals and is regarded as a promising soil washing agent. Previous studies indicate that carboxylic groups dominate metal binding to humic acid. In this study, a synthetic humic-like acid (SHLA) with high COOH content (5.03 mmol/g) was used as a washing agent to remove metals (Cu, Zn, Ni, Pb, As) from two contaminated agricultural soils (Soil 1 (pH: 6.17 ± 0.11; organic carbon: 5.91 ± 0.40%; Cu: 302.86 ± 3.97 mg/kg; Zn: 700.45 ± 14.30 mg/kg; Pb 323.56 ± 4.84 mg/kg; Ni: 140.16 ± 1.59 mg/kg) and Soil 2 (pH: 9.83 ± 0.01; organic carbon: 2.52% ± 0.25%; Cu: 242.81 ± 10.66 mg/kg; Zn: 841.00 ± 22.31 mg/kg, Pb 451.21 ± 1,92 mg/kg, As: 242.23 ± 5.24 mg/kg)). The effects of solution pH (4 to 11), liquid/solid ratio (L/S ratio, 5:1 (mL:g) to 80:1 (mL:g)), SHLA concentration (100 mg/L to 2000 mg/L), and contact time (0 to 1440 min) on % metal removal were investigated and optimum conditions identified: pH of 9, L/S ratio of 1:80, SHLA concentration of 1500 mg/L at 25 °C for 4 h. Under optimum conditions, a single washing removed 45.2% of Cu, 34.6% of Zn. 42.2% of Ni and 15.6% of Pb from Soil 1, and 30.6% of Cu, 28.1% of Zn. 14.6% of As and 18.1% of Pb from Soil 2. A modified BCR extraction of the two soils before and after washing indicated that the SHLA mainly removed metals in the exchangeable and acid soluble fraction and reducible fraction, which could effectively reduce bioavailability and environmental risk of metals. On a molar basis, SHLA was a more effective washing agent than commercial humic acid, Na₂EDTA, citric acid and tartaric acid. Overall, SHLA shows great potential for use as a soil washing agent.
图文摘要:

25909. 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.

25910. 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.
图文摘要:

25911. 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.
图文摘要:

25912. 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.

25913. 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⁺.
图文摘要:

25914. 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.

25915. 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.
图文摘要:

25916. 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.
图文摘要:

25917. 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.
图文摘要:

25918. 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.
图文摘要:

25919. 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.
图文摘要:

25920. 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.
图文摘要: