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25821. 题目: Mobilization of Cu and Pb from multi-metal contaminated soils by dissolved humic substances extracted from leonardite and factors affecting the process
文章编号: N19030504
期刊: Journal of Soils and Sediments
作者: Gianina Elena Damian, Valer Micle, Ioana Monica Sur
更新时间: 2019-03-05
摘要: Purpose: The aim of the research was to determine the potential of dissolved humic substances extracted from leonardite to mobilize Cu and Pb from multi-metal contaminated soils with the scope of finding an efficient washing solution as a possible substitute for conventional washing agents used to extract heavy metals from polluted soils around mining areas. Materials and methods: The efficiency of dissolved humic substances extracted from leonardite to extract Cu and Pb from multi-metal contaminated soil collected from “Larga de Sus” mine (Romania) was determined under batch conditions by single-step extraction. All extraction experiments were conducted in a stirrer with orbital rotation-oscillation and thermostat cupola at 100 oscillations/min and oscillation amplitude of 32 mm. The influence of stirring time (120, 240, 360, 720, 1440, 2400 min), concentration of humic solution (2% and 5%), and soil:solution ratio (mass:volume (m/V)) of 1:8, 1:10, and 1:16 on the Cu and Pb removal efficiency was investigated. The heavy metal concentration from soil and extractant solution was determined through atomic absorption spectrometry. Results and discussion: The Cu and Pb removal process from soil using dissolved humic substances proceeded relatively quickly. In investigated experimental conditions, the best Cu and Pb removal efficiencies were observed after 360 min of stirring when 60.3% of Cu and 48% of Pb were extracted from soil (2% humic washing solution). The removal efficiency of Cu increased with increasing the soil:solution ratio and humic solution concentration, at shorter stirring times. In the case of Pb, an important improvement of the mobilization with an increasing soil:solution ratio or humic solution concentration was not observed, along with investigated stirring time. A soil:solution ratio of 1:8 was sufficient to reduce the Cu concentration in the studied soil below the intervention threshold established by Romanian legislation, after 360 min of stirring. Conclusions: The mobilization of Cu and Pb from multi-metal contaminated soil using dissolved humic substances is strongly dependent on stirring time, soil:solution ratio, and concentration of humic washing solution. Nevertheless, the results of the present study demonstrate that dissolved humic substances extracted from leonardite are fairly effective washing agents for soils polluted with Cu, Pb, multiple heavy metals, and other pollutants in high concentrations.

25822. 题目: Extensive Dark Production of Hydroxyl Radicals from Oxygenation of Polluted River Sediments
文章编号: N19030503
期刊: Chemical Engineering Journal
作者: Peng Liao, Kai Yu, Yang Lu, Pei Wang, Yuzhen Liang, Zhenqing Shi
更新时间: 2019-03-05
摘要: Hydroxyl radical (•OH) is the most powerful reactive oxygen species that plays a critical role in the redox transformation of elements and contaminants. While recent advances have recognized the dark production of hydroxyl radical (•OH) from oxygenation of natural waters and subsurface sediments at anoxic-oxic interfaces, much less is known regarding the dark production of •OH from river sediments, the important component in environments. In this study, we collected 22 polluted river sediments spanning a large gradient and area along the main stem of Maozhou river watershed of southern China. Using a combination of field measurements, bench-scale experiments, and complementary characterization techniques, we provided robust evidence that the transportation of river sediment from anoxic to oxic conditions triggered the extensive production of •OH. The cumulative •OH concentrations produced within 48 h across all sediments ranged from 57 to 1479 μmol/kg (or 88–2294 μM in sediment pore water), much higher than those reported previously from subsurface sediments and anoxic waters. Sediment Fe(II) is the main contributor to •OH production, although organic carbon may also contribute to a degree. Because river sediments contained abundant Fe(II) and organic carbon, and the anoxic-oxic interfaces are ubiquitous in river sediments, we expect that the extensive dark production of •OH from oxygenation of river sediments is widespread and represents a previously under-appreciated source of •OH production. Findings of this study provide novel insights for the understanding of carbon cycling and micropollutant fate, which are valuable for designing efficient sediment remediation strategies.
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25823. 题目: Root exudation of carbohydrates and cations from barley in response to drought and elevated CO 2
文章编号: N19030502
期刊: Plant and Soil
作者: Olga C. Calvo, Jürgen Franzaring, Iris Schmid, Andreas Fangmeier
更新时间: 2019-03-05
摘要: Background and aims: Given that environmental factors like atmospheric CO₂, temperature, and water availability will likely change simultaneously, it is difficult to make accurate predictions about future crop production. Effects of elevated CO₂ or drought on aboveground plant growth are relatively well studied, while effects on the rhizosphere are rarely dealt with. The present work investigates the root exudation pattern of different osmotic protectants such as ions and sugars of two cultivars of barley grown under different water and CO₂ levels. Methods: Barley (Hordeum vulgare L.) plants were grown in plant containers in climate chambers with an optimal and reduced water supply and two CO₂ concentrations (380 and 550 ppm) and harvested at the stem elongation growth stage and when the inflorescences emerged. Results: The responses of root exudation to CO₂ enrichment, watering level, and cultivar and their interactions varied with the developmental stage. While K⁺/Na⁺ ratio in root exudates remained stable at the stem elongation stage (DC30), it was higher at the booting stage (DC49) in the cv. “Bambina” than in cv. “Golden Promise”. At DC30, in general the exudation of sugars, dissolved organic carbon (DOC) and their ratio (SUG/DOC) were lower at e[CO₂] compared to ambient CO₂ at normal watering conditions. Under reduced watering conditions, plants exuded on average 55% more sucrose than under well-watered conditions. The modern cv. BA exuded on average 53% more fructose than the older cv.GP. In contrast, at DC49, sucrose, DOC and SUG/DOC exudation were not affected by any factor. At e[CO₂] plants exuded on average 39% less fructose than under ambient CO₂. A water and CO₂ interaction on glucose exudation was found at this stage. Under reduced water conditions, plants growing at ambient CO₂ exuded less glucose but at e[CO₂] exuded similar (GP) or even higher (BA) glucose levels than under normal water supply. Although drought and cultivar factors affected the root exudation of barley, the strongest effects in the exudation pattern were caused by CO₂. Conclusions: This study presents a non-destructive percolation method for the collection of root exudates which can be used to give an insight into the complex interaction between global warming-associated environmental factors that cause yield losses and changes in crop quality and components of the belowground plant metabolism.

25824. 题目: Effect of pyrolysis conditions on the total contents of polycyclic aromatic hydrocarbons in biochars produced from organic residues: Assessment of their hazard potential
文章编号: N19030501
期刊: Science of The Total Environment
作者: José M. De la Rosa, Águeda M. Sánchez-Martín, Paloma Campos, Ana Z. Miller
更新时间: 2019-03-05
摘要: The interest of using biochar, the solid byproduct from organic waste pyrolysis, as soil conditioner is significantly increasing. Nevertheless, persistent organic pollutants, such as polycyclic aromatic hydrocarbons (PAHs), are formed during pyrolysis due to the incomplete combustion of organic matter. Consequently, these pollutants may enter the environment when biochar is incorporated into soil and cause adverse ecological effects. In this study, we examined the content of the 16 United States Environmental Protection Agency (USEPA) PAHs in biochars produced from rice husk, wood, wheat and sewage sludge residues using three different pyrolytic reactors and temperatures (400, 500 and 600 °C). The total concentration of PAHs (∑PAH) ranged from 799 to 6364 μg kg⁻¹, being naphthalene, phenanthrene and anthracene the most abundant PAHs in all the biochars. The maximum amount of PAHs was observed for the rice husk biochar produced in the batch reactor at 400 °C, which decreased with increasing temperature. The ∑PAH value of the wood biochar produced via traditional kilns doubled compared with the wood biochar produced using the other pyrolytic reactors (5330 μg kg⁻¹ in Kiln; 2737 μg kg⁻¹ in batch and 1942 μg kg⁻¹ in the rotary reactor). Looking for a more reliable risk assessment of the potential exposure of PAHs in biochar, the total toxic equivalent concentrations (TTEC) of the 14 produced biochars were calculated. When comparing the same feedstock and temperature, TTEC values indicated that the rotary reactor produced the safest biochars. In contrast, the biochars produced using the batch reactor at 400 and 500 °C have the greatest hazard potential. Our results provide valuable information on the potential risk of biochar application for human and animal health, as well as for the environment due to PAHs contamination.
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25825. 题目: Plant functional types and temperature control carbon input via roots in peatland soils
文章编号: N19030408
期刊: Plant and Soil
作者: Lilli Zeh, Juul Limpens, Björn Erhagen, Luca Bragazza, Karsten Kalbitz
更新时间: 2019-03-04
摘要: Aims: Northern peatlands store large amounts of soil organic carbon (C) that can be very sensitive to ongoing global warming. Recently it has been shown that temperature-enhanced growth of vascular plants in these typically moss-dominated ecosystems may promote microbial peat decomposition by increased C input via root exudates. To what extent different plant functional types (PFT) and soil temperature interact in controlling root C input is still unclear. In this study we explored how root C input is related to the presence of ericoid shrubs (shrubs) and graminoid sedges (sedges) by means of a factorial plant clipping experiment (= PFT effect) in two peatlands located at different altitude (= temperature effect). Methods: By selective clipping of shrub and sedge shoots in mixed vegetation at two Alpine peatland sites we interrupted the above- to belowground translocation of C, thus temporarily inhibiting root C release. Subsequent measurements of soil respiration, dissolved organic carbon (DOC) concentration and stable isotope composition (¹³C) of DOC in pore water were used as proxies to estimate the above- to belowground transfer of C by different PFT. Results: We found that soil respiration rates and DOC concentrations temporarily decreased within 24 h after clipping, with the decrease in soil respiration being most pronounced at the 1.4 °C warmer peatland after clipping shrubs. The transient drop in DOC concentration coincided with a shift towards a heavier C isotope signature, indicating that the decrease was associated with inhibition of a light C source that we attribute to root exudates. Together these results imply that shrubs translocated more C into the peat than sedges, particularly at higher temperature. Conclusions: We showed that plant functional type and temperature interact in controlling root C input under field conditions in peatlands. Our results provide a mechanistic evidence that shrubs may potentially promote the release of stored soil C through root-derived C input.

25826. 题目: Historical trends and spatial distributions of polycyclic aromatic hydrocarbons in the upper reach of the Huai River, China: Evidence from the sedimentary record
文章编号: N19030407
期刊: Applied Geochemistry
作者: Jinglan Feng, Menglin Liu, Jiahui Zhao, Pengtuan Hu, Fei Zhang, Jian-Hui Sun
更新时间: 2019-03-04
摘要: The historical trends and spatial distributions of 15 polycyclic aromatic hydrocarbons (PAHs) in sediments from the upper reach of the Huai River were investigated. The concentrations of total PAHs (ΣPAHs) in the surface sediments varied from 3.96 to 379 ng/g (average: 65.3 ng/g). PAHs in the surface sediments of the studied area were at a low level compared with some other rivers around the world. The component characteristics showed that four-ring PAHs were predominant. The principal component analysis-multiple linear regression (PCA/MLR) showed that PAHs in the surface sediments primarily originated from coal combustion and vehicular emissions, which accounted for 62.7% and 37.3% of ΣPAHs, respectively. The concentration of ΣPAHs in the sediment core ranged from 2.31 to 21.9 ng/g with deposition flux ranging from 1.91 to 33.3 ng/cm²/year. The historical pattern of PAHs correlated with the Chinese socioeconomic conditions during 1912–2014, confirming that PAHs are a sensitive tracer for anthropogenic activity. Since the 1980s, there was a sharp increase in PAHs concentrations in the studied core. PCA/MLR showed that PAHs in the sediment core were mainly from the burning of fossil fuels. The concentration of PAHs in the surface sediment and sediment core was affected by the content of total organic carbon and black carbon. The result revealed in this study could serve as a reference for the development of relevant remedial strategies for the management of the Huai River.

25827. 题目: Effects of re-vegetation type and arbuscular mycorrhizal fungal inoculation on soil enzyme activities and microbial biomass in coal mining subsidence areas of Northern China
文章编号: N19030406
期刊: CATENA
作者: Li Xiao, Yinli Bi, Shanzhou Du, Yi Wang, Chen Guo
更新时间: 2019-03-04
摘要: Coal mining subsidence leads to the degradation of vegetation cover and reduces soil quality. Soil microbes play a critical role in the recycling of soil nutrients and soil fertility. Both arbuscular mycorrhizal fungi (AMF) and artificial re-vegetation play key roles in regulating biogeochemical systems. Here, we investigated the effects of AMF inoculation and artificial re-vegetation type on soil invertase, urease and alkaline phosphatase activities, soil microbial biomass carbon (MBC), soil microbial biomass nitrogen (MBN), and their correlations with soil physicochemical properties using redundancy analysis and partial redundancy analysis in order to enhance and reclaim soil quality and the ecological efficiency of coal mining subsidence areas. The results show that soil nutrients and soil enzyme activities in FM (inoculated with Funneliformis mosseae) soils were significantly higher than in control (uninoculated) soils under all re-vegetation types, and soil organic carbon content (SOC) was highest in Hippophae rhamnoides (HR) soils. Soil MBC followed the order HR > Amorpha fruticosa (AF) > Xanthoceras sorbifolium (XS) > Cerasus humilis (CH). Soil total nitrogen (TN), dissolved organic nitrogen (DON) and nitrate nitrogen (NO₃^—N) were key factors affecting soil microbial activity in the FM soils, whereas SOC, DON, and soil C/N ratio were the important factors in control soils. Soil microbial activity was affected by soil factors to different degrees. AMF are essential for plant acquisition of soil resources, especially soil nitrogen. AMF were correlated with the potential activities of N acquisition enzymes in soil and affected N cycling in the coal mining subsidence soils.

25828. 题目: The effect of long-term fertilization on peat in an ombrotrophic bog
文章编号: N19030405
期刊: Geoderma
作者: Tim R. Moore, Klaus-Holger Knorr, Lauren Thompson, Cameron Roy, Jill L. Bubier
更新时间: 2019-03-04
摘要: Peat accumulation makes nutrient-limited ombrotrophic bogs important carbon sinks, while enhanced atmospheric nitrogen (N) deposition threatens this capacity. Here we show that the stoichiometry of peat and porewater, a control of plant growth and decomposition, has been altered in response to long-term N, phosphorus (P), and potassium (K) fertilization at Mer Bleue ombrotrophic bog in eastern Ontario, Canada. In N-fertilized peat, receiving up to an additional 6.4 g N m⁻² y⁻¹ above ambient deposition, we found N significantly (p < 0.05) greater, P both significantly greater and smaller dependent on treatment concentration, calcium (Ca) and K concentrations significantly lower, relative to control plots. In NPK-fertilized peat, P was greater than control while Ca was significantly smaller. In the porewater of N- and NPK-fertilized peat, we observed significantly more ammonium, nitrate, dissolved organic nitrogen, phosphate, and dissolved organic phosphorus than in the controls. Fourier-transform infrared (FTIR) spectroscopic analysis demonstrated that fertilization in all treatments increased decomposition, as indicated by residual enrichment of refractory moieties such as aromatics, carboxylates, and lignin, albeit only in the uppermost depths. Changes in peat quality may, however, not only relate to advanced decomposition but also to changes in litter input, as predominant vascular vegetation in the fertilized plots shared several features in FTIR spectra with samples of uppermost peat layers. Our results demonstrate that the peat in this ombrotrophic bog has responded to long-term fertilization with loss of Sphagnum moss and its filter function, increased shrub cover and enhanced decomposition.

25829. 题目: How does gypsum increase the organic carbon stock of an Oxisol profile under sugarcane?
文章编号: N19030404
期刊: Geoderma
作者: Larissa Gomes Araújo, Djalma Martinhão Gomes de Sousa, Cícero Célio de Figueiredo, Thomaz Adolpho Rein, Rafael de Souza Nunes, João de Deus Gomes dos Santos Júnior, Juaci Vitória Malaquias
更新时间: 2019-03-04
摘要: Gypsum is already a well-known soil conditioner, especially in regions with predominantly acidic soils. More recently gypsum has also been recognized as a strategy to increase carbon (C) accumulation in the soil, thus contributing to reduced C emissions agriculture. However, there are still doubts regarding how gypsum influences soil C accumulation and the role of the root system in this process. The objective of the present study was to evaluate the influence of gypsum on C accumulation and the relationships of C with soil chemical properties and development of the sugarcane root system to a depth of 2 m, evaluated in the field with an Oxisol. The experiment was arranged in a randomized complete block design, with four replications and two treatments: control (without gypsum) and gypsum application (5 t ha⁻¹). Sugarcane stalk biomass and straw production were evaluated in the first planted sugarcane and six ratoon crops. At 87 months after gypsum application, after the seventh cut, the soil was sampled in the depth of 0–200 cm, in 20 cm intervals, for evaluation of the root dry weight (RW) and soil chemical properties (S-SO₄²⁻), calcium (Ca²⁺), aluminum saturation (Al³⁺ saturation), pH, free fulvic acid carbon (FFAC), total C (TC) and particulate C (PC). Stocks of PC and TC were also estimated. The application of 5 t ha⁻¹ gypsum favored the increase of S-SO₄²⁻ and Ca²⁺ contents and induced a reduction in Al³⁺ saturation in the soil profile. In association with these improvements in the chemical properties of the subsurface layers were increases in the RW, FFAC, TC and PC stocks. After 87 months of gypsum application, the TC and PC stocks increased by 12.3 and 2.2 t ha⁻¹, respectively, in the 0–200 cm layer, with the highest gains in the 40–200 cm layer. The multivariate analysis showed that in the 40–200 cm layer of this extremely weathered soil, the effect of gypsum on increasing TC and PC stocks, as well as FFAC, is a result of the reduced Al³⁺ saturation associated with the increase in nutrients such as Ca and S, stimulating greater root development.

25830. 题目: Dominant extracellular enzymes in priming of SOM decomposition depend on temperature
文章编号: N19030403
期刊: Geoderma
作者: Qianyuan Liu, Xingliang Xu, Huimin Wang, Evgenia Blagodatskaya, Yakov Kuzyakov
更新时间: 2019-03-04
摘要: Decomposition of soil organic matter (SOM) is operated by microbial extracellular enzymes and is dependent on temperature. It remains unclear how input of labile organics interacts with temperature on SOM decomposition. Soil samples collected from a temperate forest were incubated for 3 months to quantify SOM decomposition and its priming induced by input of ¹⁴C-labelled glucose at five temperatures (from 3 to 31 °C with an interval of 7 °C). The activities of eight extracellular enzymes were measured four times during the incubation. Increasing temperature accelerated SOM decomposition with a temperature sensitivity (Q₁₀) value ranging from 1.3 to 4.4. Response of priming to temperature was mediated by the activity and variety of extracellular enzymes temporally: (1) priming increased with increasing temperature at the initial stage; (2) subsequently, priming at lower temperature gradually exceeded those at higher temperature; and (3) finally, priming at high temperature was higher than at low temperatures. At higher temperatures (17–31 °C), N-acquiring enzymes (leucine amino peptidase and N-acetyl-β-d-glucosaminidase) dominated at the early stage of priming, but C-acquiring enzymes (β-glucosidase and xylanase) dominated at later stages. Priming exhibited a hysteresis at low temperatures (3–17 °C) with C-acquiring enzyme (β-galactosidase) dominating at the initial stage, C-and P-acquiring enzymes (α-glucosidase and phosphomonoesterase) at the middle stage, and C-acquiring enzymes (β-galactosidase and xylanase) at the later stage. Consequently, microbial extracellular enzymes were produced in terms of nutrient availability over time depended on temperature. Such acclimation of microbial extracellular enzymes to temperature and nutrient availability should be considered to predict responses of C cycling to global change.
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25831. 题目: The Monsoon, Carbon Fluxes, and the Organic Carbon Pump in the Northern Indian Ocean
文章编号: N19030402
期刊: Progress in Oceanography
作者: Tim Rixen, Birgit Gaye, Kay Emeis
更新时间: 2019-03-04
摘要: Time series sediment trap experiments were carried out at fifteen sites in the northern Indian Ocean between 1986 and 2007. The data on particle flux rates and composition are analyzed in combination with satellite-derived estimates of primary production and results of surface ocean studies during the Joint Global Ocean Flux Study in the Arabian Sea (JGOFS-Indik). The data highlight the influence of the monsoon on the transport of organic carbon into the deep sea and the associated functioning of the organic carbon pump.The results illustrate the well-known concept of export production, which is driven by inputs of nutrients from the aphotic zone and external reservoirs (the atmosphere and the land) into the euphotic zone. The monsoon drives the organic carbon export through its impact on the physical nutrient supply mechanisms, such as upwelling, vertical mixing, and river discharges. Eolian dust and especially riverine supply of lithogenic matter increase organic carbon fluxes by accelerating the transport of organic matter into the deep sea. Nevertheless, it is preferentially respired in the sub-thermocline and the resulting trapping of remineralized nutrients at this water-depth enforces the influence of upwelling and vertical mixing on the organic carbon fluxes which in the northern Indian Ocean are among the highest worldwide.Model experiments and measured organic carbon burial rates indicate that a weakening of the summer monsoon strength hardly affected the long-term annual average organic carbon export flux into the deep sea during the last approximately 7000 years. In addition to the summer and winter monsoon strength, which are assumed to be inversely related to each other, monsoon-driven physical impacts on the nutrient trapping efficiency seem to have kept organic carbon fluxes at a high level. A feedback mechanism caused by negative impacts of oxygen concentrations on the respiration and thus nutrient trapping efficiency apparently prevents the development of anoxia to the point where sulfate reduction occurs and sets an upper limit to organic carbon fluxes. Whether changes in the phytoplankton community structure observed in recent decades indicate that this self-regulating system is becoming unstable is open to question.

25832. 题目: Visible light-activated degradation of natural organic matter (NOM) using zinc-bismuth oxides-graphitic carbon nitride (ZBO-CN) photocatalyst: Mechanistic insights from EEM-PARAFAC
文章编号: N19030401
期刊: Chemosphere
作者: Hai Bang Truong, Bui The Huy, Quang Viet Ly, Yong-Ill Lee, Jin Hur
更新时间: 2019-03-04
摘要: In this study, the complex degradation behavior of natural organic matter (NOM) was explored using photocatalytic oxidation systems with a novel catalyst based on a hybrid composite of zinc-bismuth oxides and g-C₃N₄ (ZBO-CN). The photooxidation system demonstrated the effective removal of NOM under low-intensity visible light irradiation, presenting removal rates of 53–74% and 65–88% on the basis of dissolved organic carbon (DOC) and the UV absorption coefficient (UV₂₅₄), respectively, at 1.5 g/L of the catalyst. The NOM removal showed an increasing trend with a higher ZBO-CN dose. Comparative experiments with the hole and OH radical scavengers revealed that the direct oxidation occurring on the catalyst's surface might be the governing photocatalytic mechanism. Fluorescence excitation emission matrix-parallel factor analysis (EEM-PARAFAC) revealed the individual removal behavior of the different constituents in bulk NOM. Different tendencies towards preferential adsorption and subsequent oxidative removal were found among dissimilar fluorescent components within a bulk terrestrial NOM, following the order of terrestrial humic-like (C1) > humic-like (C2) > microbial humic-like (C3) components. The result suggests the dominant operation of π-π and/or hydrophobic interactions between the NOM and the catalyst. The discriminative removal behavior was more pronounced in visible light versus UV-activated systems, probably due to the incapability of visible light to excite è - h⁺ pairs of ZnO and the triplet state of NOM. The high photoactivity and structural stability of ZBO-CN under visible light implies its potential for an effective, low-cost and energy-saving treatment technology to selectively remove large sized humic-like substances from water.
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25833. 题目: The aging behaviors of chromophoric biomass burning brown carbon during dark aqueous hydroxyl radical oxidation processes in laboratory studies
文章编号: N19030309
期刊: Atmospheric Environment
作者: Xingjun Fan, Xufang Yu, Yan Wang, Xin Xiao, Feiyue Li, Yue Xie, Siye Wei, Jianzhong Song, Ping’an Peng
更新时间: 2019-03-03
摘要: This study was conducted to explore the aging behavior of biomass burning (BB) emitted brown carbon (BrC) during an aqueous hydroxyl radical (OH) oxidation process in the absence of light. The evolution characteristics of rice straw (RS) and pine wood (PW) emitted BrC were monitored by UV-vis, synchronous fluorescence and excitation-emission matrix (EEM) spectroscopies combined with two-dimensional correlation spectroscopy (2D-COS) and parallel factor (PARAFAC) analysis. The results indicated that OH radical oxidation could greatly weaken the absorption and fluorescence intensity of both BB BrC, implying the significant degradation of chromophoric BB BrC. EEM-PARAFAC analysis identified one humic-like (C2) and two protein-like (C1, C3) components from BB BrC. The intensities of these fluorescent components all steadily decreased with oxidation, in which the tryptophan-like substance (C1) presented pronounced reduction for both BB BrC. However, the C2/C1 and C3/C1 intensity ratios exhibited an increasing trend with oxidation time, suggesting that the distribution of humic-like (C2) and tyrosine-like (C3) components within BrC could be enhanced during dark OH oxidation processes. These findings suggested that the levels and types of chromophores and fluorophores within BB BrC had been transformed once they were emitted to atmosphere, resulting in the change of optical properties of BB BrC. 2D-absorption-COS demonstrated that the decomposition of chromophores within the high ultraviolet region (275–310 nm) occurred preferentially to those within the low ultraviolet region (225–260 nm). In addition, the 2D-COS combined with fluorescence spectra for both BrC showed that the oxidation of types of fulvic-like fluorophores (340–380 nm) occurred before protein-like fractions (250–300 nm). These results provide detailed knowledge of the aqueous OH radical oxidation process of BB BrC in the atmosphere and are of great significance for understanding the climate and environmental effects of BB BrC and refining the atmospheric models established on the optical properties of BrC.

25834. 题目: Environmental fate of chlordecone in coastal habitats: recent studies conducted in Guadeloupe and Martinique (Lesser Antilles)
文章编号: N19030308
期刊: Environmental Science and Pollution Research
作者: Charlotte R. Dromard, Damien A. Devault, Yolande Bouchon-Navaro, Jean-Pierre Allénou, Hélène Budzinski, Sébastien Cordonnier, Nathalie Tapie, Lionel Reynal, Soazig Lemoine, Jean-Pierre Thomé, Emmanuel Thouard, Dominique Monti, Claude Bouchon
更新时间: 2019-03-03
摘要: The organochlorine pollution by chlordecone, an insecticide spread in the past in banana plantations, is now recognized as a major ecological, economic, and social crisis in Guadeloupe and Martinique Islands. Due to its physical and chemical properties, this molecule is particularly persistent in the natural environment. Volcanic soil of Guadeloupe and Martinique contain allophanes (amorphous clays), which favor chlordecone trapping due to their structure and physical properties. Thus, with this trapping ability, allophanes serve as a vector allowing chlordecone to contaminate runoff waters and, finally, the sea. In the present publication, several studies recently conducted in the Lesser Antilles have been compiled in order to evaluate the desorption of chlordecone from allophanes when arriving in the estuarine environment and to determine the transfer of chlordecone along marine trophic food webs. The experiments showed that 20% of the initial quantity of chlordecone was released from allophanes in estuarine conditions and 10% in the marine environment. These results could explain the high level of contamination found in the suspended organic matter and zooplankton in the coastal areas located downstream of the contaminated watersheds. The contamination of the marine food webs of mangroves, seagrass beds, and coral reefs is dominated by a contamination “by bath” in littoral waters containing chlordecone and by bioamplification seawards.

25835. 题目: 3D Hierarchical Porous-Structured Biochar Aerogel for Rapid and Efficient Phenicol Antibiotics Removal from Water
文章编号: N19030307
期刊: Chemical Engineering Journal
作者: Hui Liu, Yuanfeng Wei, Jinming Luo, Tong Li, Dong Wang, Shenglian Luo, John C. Crittenden
更新时间: 2019-03-03
摘要: The appearance and contamination of phenicol antibiotics (PABs), such as chloramphenicol (CAP), florfenicol (FF) and thiamphenicol (TAP), in aqueous solutions has aroused public concerns in recent years due to its negative impact on human health and ecological system. In this study, a 3D porous-structured biochar aerogel (3D-PBA) with large BET surface area (2607 m²/g) was synthesized, and applied on PABs removal. Notably, to the best of our knowledge, among all the reported carbon-based adsorbents, 3D-PBA shows the record high adsorption capacity toward target PABs. The adsorption capacity for CAP, FF and TAP was measured to be 786.1, 751.5 and 691.9 mg/g at 298 K, respectively. The Langmuir-Freundlich isotherm model can better describe the adsorption isotherm data. Specifically, 2 mg/L PABs can be completely removed within 10 min, and over 90% PABs can be removed within 10 min even when the initial concentration was as high as 40 mg/L. Adsorption mechanism of PABs on 3D-PBA was fully determined using XPS and FTIR. As a result, the pore-filling effect, π-π/n-π EDA interaction and electrostatic interaction played a crucial role, and it also accompany with hydrogen bonding interaction. Furthermore, the synergistic action of hydrophobic interaction also acts as indispensable role during the adsorption process. Overall, the 3D-PBA can act as an efficient candidate for ultrafast PABs removal.
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25836. 题目: Transparent Exopolymer Particle (TEP) distribution and in situ prokaryotic generation across the deep Mediterranean Sea and nearby North East Atlantic Ocean
文章编号: N19030306
期刊: Progress in Oceanography
作者: Eva Ortega-Retuerta, Ignacio P. Mazuecos, Isabel Reche, Josep M. Gasol, Xosé A. Álvarez-Salgado, Marta Álvarez, María F. Montero, Javier Arístegui
更新时间: 2019-03-03
摘要: Transparent exopolymer particles (TEP) play a key role in ocean carbon export and structuring microbial habitats, but information on their distribution across different ocean basins and depths is scarce, particularly in the dark ocean. We measured TEP vertical distribution from the surface to bathypelagic waters in an east-to-west transect across the Mediterranean Sea (MedSea) and the adjacent North Eastern Atlantic Ocean (NEA), and explore their physical and biological drivers. TEP ranged from 0.6 to 81.7 µg XG eq L^-1, with the highest values in epipelagic waters above the deep chlorophyll maximum, and in areas near the Gibraltar and Sicily Straits. TEP were significantly related to particulate organic carbon (POC) in all basins and depth layers (epipelagic vs. deep), but the contribution of TEP to POC was higher in the NEA (85%, 79% and 67% in epi-, meso- and bathypelagic waters, respectively) than in the MedSea (from 53% to 62% in epipelagic waters, and from 45% to 48% in meso- and bathypelagic waters), coinciding with higher carbon to nitrogen particulate organic matter ratios in the NEA. The TEP connectivity between epipelagic waters and mesopelagic waters was less straightforward than between mesopelagic waters and bathypelagic waters, with a 23% and 55 % of the variance in the relationship between layers explained respectively. Prokaryotes were found to be a likely net source of TEP as inferred by the significant direct relationship observed between prokaryotic heterotrophic abundance and TEP. This assumption was confirmed using experimental incubations, where prokaryotes produced TEP in concentrations ranging from 0.7 (Western Mediterranean, bathypelagic) to 232 (Western Mediterranean, mesopelagic) µg XG eq. L^-1 day^-1.

25837. 题目: Deciphering the suppressiveness of banana Fusarium wilt with organic residues
文章编号: N19030305
期刊: Applied Soil Ecology
作者: Daniel Winter Heck, Raquel Ghini, Wagner Bettiol
更新时间: 2019-03-03
摘要: The use of organic residues in agriculture can contribute to the management of plant diseases and improvements in soil fertility. However, their effects on banana Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense (Foc), are poorly understood. In this study, the biotic and abiotic effects on soil suppressiveness of banana Fusarium wilt were evaluated after incorporation of composted sewage sludge, biochar, shrimp peels and mussel shells into the soil. Residues were incorporated at rates of 0, 1, 2, 3, 4, and 5%, v:v in soil previously infested with Foc. Plantlets of banana cv. Maçã (AAB) were transplanted seven days after residue incorporation. Notable with respect to the other residues and concentrations studied, sewage sludge at 4% and 5% reduced plant disease (disease severity index and external severity) and increased plant growth. All concentrations of biochar and sewage sludge at 2% and 3% had intermediate effects. Disease severity and plant growth in plants grown in soil containing shrimp peels and mussel shells were similar to those of the untreated control. Negative correlations were observed between disease parameters and soil basal respiration, bacterial population, electrical conductivity, pH, V% (base saturation), CEC, P, K, Ca, Mg, Na, Zn, Mn and B.

25838. 题目: Rhizosphere microbial biomass is affected by soil type, organic and water inputs in a bell pepper system
文章编号: N19030304
期刊: Applied Soil Ecology
作者: Kuan Qin, Xuejun Dong, John Jifon, Daniel I. Leskovar
更新时间: 2019-03-03
摘要: Effects of environmental and management factors on the diversity and abundance of rhizosphere microbes in unmanaged ecosystems are well established. However, there is limited information about these interactions in vegetable cropping systems. In this two-year field study, we used organic amendments (humic substances, HS) and water supply (deficit irrigation) as soil management factors to characterize changes in bell pepper rhizosphere microbial population under two distinct soil types (clay and sandy). Path analysis revealed that soil type was the main factor constructing the microbial population. Clay soil indirectly increased bacterial biomass through the changes in root length, soil pH, P and K contents, while increased fungal biomass was linked with the enhanced above-ground plant yield. As organic inputs, HS had long-term positive influences on soil microbial activity through improvements in soil organic carbon content, which was also positively correlated with bacterial population. Water input became a less influential factor – deficit irrigation indirectly decreased fungal biomass but increased soil respiration through the reduction in pepper yield. These findings provide a better understanding of external factors controlling the abundance of rhizosphere microbiota under intensively managed cropping systems, and potential strategies to improve beneficial microbial diversity and soil health.

25839. 题目: Exploring the links between bacterial communities and magnetic susceptibility in bulk soil and rhizosphere of beech (Fagus sylvatica L.)
文章编号: N19030303
期刊: Applied Soil Ecology
作者: Carolina Chiellini, Valeria Cardelli, Mauro De Feudis, Giuseppe Corti, Stefania Cocco, Alberto Agnelli, Luisa Massaccesi, Giulia Donato Alessi, Alessio Mengoni, Stefano Mocali
更新时间: 2019-03-03
摘要: Soil magnetic properties are sensitive indicators of pedogenetic processes. Although many of the processes that increase soil magnetism are well documented, the role of microbial communities and the metabolic characteristics of Fe-reducing bacteria are still largely unknown. For this work, two soils with contrasting magnetic properties were identified in a beech forest on Monte Zuccarello (central Italy). Samples of bulk soil and rhizosphere were obtained from A (0–7 cm), AB (7–16 cm), Bw1 (16–22 cm) and Bw2 (22–29 cm) horizons of both soils, and were analysed for their physicochemical characteristics, the amount of magnetic minerals, and the composition of total and culturable bacterial communities, focusing on siderophore-producing bacteria (SPB). Analyses confirmed that the magnetic soil (MS) have a higher content of maghemite and magnetite association, compared to non-magnetic soil (NMS). Since the formation of maghemite can occur through different processes, we investigated on the possible role of soil bacteria in the formation of this magnetic mineral. As soil maghemite generally contains small amounts of Fe²⁺, the formation of which has been attributed to the combustion of organic matter, SPB have been isolated and identified. MS samples showed the highest number of SPB (mainly Micrococcaceae, Bacillaceae, and Pseudomonadaceae), suggesting a significant increase in Fe-reducing bacteria. High-throughput sequencing analysis revealed a separation in terms of the total composition of the bacterial community between bulk and rhizosphere of both MS and NMS, dominated by Proteobacteria, Actinobacteria, Acidobacteria, and Verrucomicrobia phyla. Interestingly, Gamma and Delta Proteobacteria, as well as Nitrospirae, were usually more abundant in MS than in NMS, confirming that the MS was predominantly characterized by groups of magnetotactic bacteria and SPB, and potentially contributing to enhance the soil magnetic properties.

25840. 题目: Role of recent climate change on carbon sequestration in peatland systems
文章编号: N19030302
期刊: Science of The Total Environment
作者: Paul H. Lunt, Ralph M. Fyfe, Alan D. Tappin
更新时间: 2019-03-03
摘要: This paper provides information on the impact of recent climate change on carbon sequestration in peatland systems in South West England. This is important because peatlands have the potential to sequester and hold large quantities of anthropogenically released CO_2. This paper investigates whether there has been a reduction in the strength of carbon sinks in a valley mire and blanket bog, which occur on the limits of the biogeographical envelop for peatlands in Britain. Past rates of carbon accumulation were calculated from peat depth and the sequential analysis of peat age, bulk density and carbon content from cores taken from valley mire and blanket bog. At the valley mire site contemporary net ecosystem carbon balance (NECB) was calculated by measuring inputs to the peat body, via net primary productivity (NPP), of Sphagna. Losses of C from the peat body were calculated by measuring CH₄, and aquatic carbon, calculated from catchment export of particulate and dissolved organic carbon. The study found similar mean rates of carbon accumulation since 1850 of 11.26 t ± 0.68 t CO₂e ha⁻¹ yr⁻¹ (307 g C m⁻² yr⁻¹) in valley mire and 11.77 t ± 0.88 t CO₂e ha⁻¹ yr⁻¹ (321 g C m⁻² yr⁻¹) in blanket bog. The mean present-day CO₂ sequestration rate for Sphagna on valley mire was calculated to be 9.13 t ± 0.98 t CO₂e ha⁻¹ yr⁻¹ (249 g C m⁻² yr⁻¹). Both past and contemporary rates of CO₂ sequestration were found to be at the maxima of those reported for temperate peatlands. NPP was found to vary according to microform with higher rates of carbon sequestration found in lawn and hummock microforms compared with pools. Our work suggests that recent changes in the climate appear to have had limited impact on the strength of peatland carbon sinks in South West England.
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