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31701. 题目: Sugarcane yield and soil carbon response to straw removal in south-central Brazil
文章编号: N18062504
期刊: Geoderma
作者: Ricardo de Oliveira Bordonal, Lauren Maine Santos Menandro, Leandro Carneiro Barbosa, Rattan Lal, Débora Marcondes Bastos Pereira Milori, Oriel Tiago Kolln, Henrique Coutinho Junqueira Franco, Jo?o Luís Nunes Carvalho
更新时间: 2018-06-25
摘要: Understanding the impacts of straw removal on quantity and quality of soil organic carbon (SOC) is crucial for sustaining or improving soil functions and producing economically viable sugarcane yields. Field experiments were carried out on commercial farms to quantify effects of straw removal on sugarcane yields, SOC stocks and the degree of soil organic matter (SOM) humification under three diverse edaphoclimatic conditions (Quirinópolis-GO, Chapad o do Céu-GO and Quatá-SP) in Brazil, while considering the effects of cover crop on sugarcane yields during two harvest seasons. Three straw removal rates (0, 50, and 100%) were arranged in a randomized block design with four replications within two paired areas, one seeded with Crotalaria spectabilis (cover crop–CC) and the other kept under bare fallow (BF) during the sugarcane-replanting period. Sugarcane yields were measured annually using an instrumented truck equipped with load cells, and soil samples were collected to a depth of 40-cm two years after establishing the trials. Straw removal for two years did not significantly influence cane yields in Quatá-SP, but in Chapad o do Céu-GO and Quirinópolis-GO, complete straw removal resulted in cumulative yield losses of up to 28 and 62 Mg ha 1 respectively. The inclusion of Crotalaria spectabilis within sugarcane cropping cycle increased two-year cumulative yields by 25 and 27 Mg ha 1 in Chapad o do Céu-GO and Quirinópolis-GO respectively. SOC response to straw removal was highly site-specific after two years. In fine-textured soils, straw removal rates did not significantly affect SOC stocks in Chapad o do Céu-GO, but in Quirinópolis-GO complete straw removal favored the depletion of SOC stock relative to partial or no straw removal in both soil layers (0–10 and 0–40 cm) of the BF area, while within the CC area SOC depletion was observed in the 0–40 cm layer. For sandy soil (Quatá-SP), complete straw removal decreased SOC stock only in the top 10 cm of the CC area. Laser-Induced Fluorescence Spectroscopy showed high degree of SOM humification in soils with depleted SOC stock, indicating that excessive straw removal was degrading soil quality by reducing the amount of labile C in the SOM. Conclusions drawn from this study indicate that, even on a short-term basis, complete straw removal already began to modify the quantity and quality of SOC, while both moderate or complete removals adversely affected sugarcane yields.

31702. 题目: Riverine particulate C and N generated at the permafrost thaw front: case study of western Siberian rivers across a 1700...
文章编号: N18062503
期刊: Biogeosciences
作者: Ivan V. Krickov, Artem G. Lim, Rinat M. Manasypov, Sergey V. Loiko, Liudmila S. Shirokova, Sergey N. Kirpotin, Jan Karlsson, and Oleg S. Pokrovsky
更新时间: 2018-06-25
摘要: In contrast to numerous studies on the dynamics of dissolved (<0.45 m) elements in permafrost-affected high latitude rivers, very little is known of the behavior of river suspended (>0.45 m) matter (RSM) in these regions. In order to test the effect of climate, permafrost and physio-geographical landscape parameters (bogs, forest and lake coverage of the watershed) on RSM and particulate C, N and P concentration in river water, we sampled 33 small and medium size rivers (10–100000km2 watershed) along a 1700km N–S transect including both permafrost-affected and permafrost-free zones of Western Siberian Lowland (WSL). The concentration of C and N in RSM decreased with the increase in river watershed size, illustrating (i) the importance of organic debris in small rivers which drain peatlands and (ii) the role of mineral matter from bank abrasion in larger rivers. The presence of lakes in the watershed increased C and N but decreased P concentrations in RSM. The C:N ratio in the RSM reflected the source from deep rather than surface soil horizon, similar to that of other Arctic rivers. This suggests the export of peat and mineral particles through suprapermafrost flow occurring at the base of the active layer. There was a maximum of particulate C and N concentration at the beginning of permafrost appearance (a sporadic and discontinuous zone, 62–64°N). This presumably reflected the organic matter mobilization from newly thawed organic horizons in soils at the active latitudinal thawing front. The results suggest that a northward shift of permafrost boundaries and an increase in active layer thickness may increase particulate C and N export by WSL rivers to the Arctic Ocean by a factor of 2, while P export may remain unchanged. In contrast, within a long-term climate warming scenario, the disappearance of permafrost in the north, the drainage of lakes and transformation of bogs to forest may decrease C and N concentration in RSM by 2 to 3 times.

31703. 题目: Quantification of lignin oxidation products as vegetation biomarkers in speleothems and cave drip water
文章编号: N18062502
期刊: Biogeosciences
作者: Inken Heidke, Denis Scholz, and Thorsten Hoffmann
更新时间: 2018-06-25
摘要: Here we present a sensitive method to analyse lignin oxidation products (LOPs) in speleothems and cave drip water to provide a new tool for paleo vegetation reconstruction. Speleothems are valuable climate archives. However, compared to other terrestrial climate archives, such as lake sediments, speleothems contain very little organic matter. Therefore, very few studies on organic biomarkers in speleothems are available. Our new sensitive method allows to use LOPs as vegetation biomarkers in speleothems. Our method consists of acid digestion of the speleothem sample followed by solid phase extraction (SPE) of the organic matter. The extracted polymeric lignin is degraded in a microwave assisted alkaline CuO oxidation step to yield monomeric LOPs. The LOPs are extracted via SPE and finally analysed via ultrahigh-performance liquid chromatography (UHPLC) coupled to electrospray ionisation (ESI) and high-resolution orbitrap mass spectrometry (HRMS). The method was applied to stalagmite samples with a sample size of 3–5g and cave drip water samples with a sample size of 100–200mL from the Herbstlabyrinth-Advent-Cave in Germany. In addition, fresh plant samples, soil water and powdered lignin samples were analysed for comparison. The concentration of the sum of eight LOPs (Σ8) was in the range of 20–84ngg 1 for the stalagmite samples and 230–440ngL 1 for the cave drip water samples. The limits of quantification for the individual LOPs ranged from 0.3–8.2ng per sample. Our method represents a new and powerful analytical tool for paleo vegetation studies and has great potential to identify the pathways of lignin incorporation into speleothems.

31704. 题目: Fodder radish seed cake biochar for soil amendment
文章编号: N18062501
期刊: Environmental Science and Pollution Research
作者: Wendel Paulo Silvestre, Paula Lúcia Galafassi, Suelem Daiane Ferreira, Marcelo Godinho, Gabriel Fernandes Pauletti, Camila Baldasso
更新时间: 2018-06-25
摘要: In this work, fodder radish seed cake (FRSC) was pyrolyzed in a rotary kiln reactor at 0, 3, and 6 rpm, at final temperature of 500 °C. Maximum biochar yield was observed at 0 rpm (≈ 26 wt.%). Increase of the rotary speed decreased the volatile matter content and increased the ash content of the biochars. Biochars exhibited alkaline pH (≈ 9.0), low electrical conductivity (< 105.6 dS m 1), and high cation exchange capacity (69 to 78 cmolc kg 1), as well as high nitrogen contents (≈ 80 g kg 1). FTIR analysis presented biochars with similar spectra, with carboxyl and carbonyl groups within the structure, along with aromatic rings and nitrogen containing functions (amides). Biochar incubation experiments in an acrisol at different biochar doses (5 g L 1 soil to 40 g L 1 soil) were performed in order to evaluate changes in soil fertility parameters caused by FRSC biochar application. Results indicated that most of macro (N, P, K, Ca, Mg) and micronutrients (S, Cu, Zn, Mn, B, Na) increased with increase of the dosage, along with the decrease in Al and H+ Al contents. An increase in pH (from 4.25 to 5.33) was also observed, in electric conductivity (from 30.0 to 45.7 dS m 1), and a decrease in soil real density (from 3.67 to 2.99 kg L 1) at the dosage of 40 g char L 1 soil.

31705. 题目: Influence of aggregation on nanoscale titanium dioxide (nTiO2) deposition to quartz sand
文章编号: N18062405
期刊: Chemosphere
作者: Zhong Tang, Tao Cheng, Leanne M. Fisher-Power
更新时间: 2018-06-24
摘要: Although extensive research has been conducted to investigate nTiO2 aggregation and deposition, effects of aggregation on concurrent/subsequent deposition of nTiO2, which has important implications to the fate and transport of nTiO2 in groundwater, has received only limited attention. The objective of this study was to investigate how pH, dissolved organic matter (DOM), and valence of background solution cation influence aggregation and concurrent/subsequent deposition of nTiO2. Experiments were performed to examine nTiO2 aggregation and deposition onto quartz sand with co-present illite, kaolinite, and montmorillonite colloids under various geochemical conditions. Results showed that nTiO2 formed hetero-aggregates (i.e., nTiO2-clay aggregates) at low pH when nTiO2 and clay colloids carried opposite charges, and the hetero-aggregates may either deposit or remain suspended depending on their interactions with quartz sand and Fe/Al oxyhydroxide coatings. Deposition of nTiO2 and/or nTiO2-clay aggregates occurred as a result of electrostatic attraction, secondary minimum, and potentially Mg2+ bridging. Humic acid prevented nTiO2 aggregation and deposition under most conditions. In MgCl2 solutions, however, it facilitated deposition by adsorbing to nTiO2 and Fe/Al oxyhydroxides, thereby enabling Mg2+ bridging. This study demonstrated the important and complex roles of pH, DOM, cation valence, and clay colloids in controlling aggregation and subsequent deposition of nTiO2.

31706. 题目: Identifying localized and scale-specific multivariate controls of soil organic matter variations using multiple wavelet coherence
文章编号: N18062404
期刊: Science of The Total Environment
作者: Ruiying Zhao, Asim Biswas, Yin Zhou, Yue Zhou, Zhou Shi, Hongyi Li
更新时间: 2018-06-24
摘要: Environmental factors have shown localized and scale-dependent controls over soil organic matter (SOM) distribution in the landscape. Previous studies have explored the relationships between SOM and individual controlling factors; however, few studies have indicated the combined control from multiple environmental factors. In this study, we compared the localized and scale-dependent univariate and multivariate controls of SOM along two long transects (northeast, NE transect and north, N transect) from China. Bivariate wavelet coherence (BWC) between SOM and individual factors and multiple wavelet coherence (MWC) between SOM and factor combinations were calculated. Average wavelet coherence (AWC) and percent area of significant coherence (PASC) were used to assess the relative dominance of individual and a combination of factors to explain SOM variations at different scales and locations. The results showed that (in BWC analysis) mean annual temperature (MAT) with the largest AWC (0.39) and PASC (16.23%) was the dominant factor in explaining SOM variations along the NE transect. The topographic wetness index (TWI) was the dominant factor (AWC = 0.39 and PASC = 20.80%) along the N transect. MWC identified the combination of Slope, net primary production (NPP) and mean annual precipitation (MAP) as the most important combination in explaining SOM variations along the NE transect with a significant increase in AWC and PASC at different scales and locations (e.g. AWC = 0.91 and PASC = 58.03% at all scales). The combination of TWI, NPP and normalized difference vegetation index (NDVI) was the most influential along the N transect (AWC = 0.83 and PASC = 32.68% at all scales). The results indicated that the combined controls of environmental factors on SOM variations at different scales and locations in a large area can be identified by MWC. This is promising for a better understanding of the multivariate controls in SOM variations at larger spatial scales and may improve the capability of digital soil mapping.
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31707. 题目: Identifying the reducing capacity of biomass derived hydrochar with different post-treatment methods
文章编号: N18062403
期刊: Science of The Total Environment
作者: Yan Yan, Xianlong Ma, Weimin Cao, Xiaolei Zhang, Jizhi Zhou, Qiang Liu, Guangren Qian
更新时间: 2018-06-24
摘要: In this study, hydrochar was prepared from wheat straw (WS) and Spartina alterniflora (SA) biomass by hydrothermal carbonization, and further treated with HCl and NaOH washing, HNO3 oxidization and low temperature thermal heating. The reducing capacity (RC) of sample was quantified by I2 titration to explore how these modification methods affected the redox properties of hydrochar. The results indicated HNO3 and thermal oxidization increased the RC of hydrochar by 2–5 folds while NaOH washing had the negative effect on samples' RC. By analyzing the excitation-emission matrix (EEM) fluorescence of alkaline extraction solution of sample, humic acid like substances generated from various methods were identified as one of the major sources for electron donating. HNO3 oxidization could significantly increase the RC in hydrochar, which was likely resulting from the generation of alkali-soluble small molecule organic compounds. However, excessive oxidation by nitric acid with prolonged duration led to the gradual decrease in hydrochar's RC. Heating treatment caused a significant increase in the content of redox-active oxygen-containing functional groups and persistent free radicals (PFRs) in hydrochar. Even though both could donate electrons in the redox reaction with I2, the former was considered a greater contributor for the RC of hydrochar. From this study, the origin of RC of hydrochar can be identified as: oxygen-containing functionality, humic-like matter and PFRs. By employing different modification methods, the RC of hydrochar could be tuned by regulating the above sources. This study provided fundamental knowledges and simple routes to manipulate the redox properties of hydrochar for different environmental applications.
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31708. 题目: Responses of microbial carbon metabolism and function diversity induced by complex fungal enzymes in lignocellulosic waste composting
文章编号: N18062402
期刊: Science of The Total Environment
作者: Zhuotong Zeng, Xueying Guo, Piao Xu, Rong Xiao, Danlian Huang, Xiaomin Gong, Min Cheng, Huan Yi, Tao Li, Guangming Zeng
更新时间: 2018-06-24
摘要: Composting is an economic and effective technology for solid waste treatment, which is an essential method to promote the biogeochemical cycle of contaminants. However, the application of this technology was limited by the bio-degradative recalcitrance of lignin and other kind of phytotoxic substances release. The combination with microorganisms and enzymes is a popular and efficient way to enhanced composting. This study, referring to metabolic mechanisms, fungal molecular and biogeochemical cycles, was performed to investigate the effects of lignin degradation, carbon metabolic diversity, as well as the related changes induced by these two kinds of complex enzymes in composting. The biological diversity is important indicator in ecosystem, which concerns the environmental applicability of one technology. The carbon metabolism diversity reflected the biogeochemical cycles of organic matter, which was also an essential input to analyze the effects of composting. The changes on the diversity characteristics of carbon are essential to comprehensively understand the deep mechanisms of this process, and extended the application of complex enzymes in the field of enhanced composting. The analysis of Biolog revealed that the utilization of pyruvic acid methyl ester, α-Cyclodextrin, d-Mannitol, d-Galacturonic, Itaconic acid and l-asparagine were deeply promoted, and that of d, l-α-Glycerol-phosphate, l-Threonine, Glycyl-l-Glutamic acid and putrescine were depressed by adding the complex enzyme in composting. Moreover, according to the data, the addition of complex enzymes improved the degradation efficiency and the metabolic capacity of carbon in composting. These findings undoubtedly contribute to the development of enzyme-based technologies and the applications of complex enzymes in composting, which is of great benefit to eliminate the limitation and extend the application of composting.
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31709. 题目: Structural response of humic acid upon binding with lead: A spectroscopic insight
文章编号: N18062401
期刊: Science of The Total Environment
作者: Nuzahat Habibul, Wei Chen
更新时间: 2018-06-24
摘要: Lead (Pb) is a widespread heavy metal that can cause damage to the ecosystem, and the ubiquitously existing dissolved organic matter (DOM) can significantly affect the environmental behavior of Pb. The present work explores the interaction process of Pb with humic acid (HA) through integration of synchronous fluorescence and log-transformed UV–vis absorption spectroscopy coupled with spectral slope calculation and two-dimensional correlation analyses. The spectral slope calculation results show that the carboxylic and phenolic groups in HA were the predominant binding sites to Pb, and the interaction process was highly dependent on solution pH. Correlation analyses confirmed a superior binding affinity of carboxylic groups in HA over phenolic groups. Integration of spectral slope calculation with two-dimensional correlation spectroscopy is a promising tool for better understanding the molecular structure of Pb-DOM complexes and the characteristics of Pb binding to DOM, which may provide new insights into the prevention, control, and remediation of Pb contamination in environment.
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31710. 题目: Quinone group enhances the degradation of levofloxacin by aqueous permanganate: Kinetics and mechanism
文章编号: N18062303
期刊: Water Research
作者: Ke Xu, Huiyu Dong, Mengkai Li, Zhimin Qiang
更新时间: 2018-06-23
摘要: Quinone group is an important fraction of humic acid. The pseudo-first-order rate constant (k obs) of levofloxacin (LF) degradation by permanganate (MnO4 ) significantly increased from 0.010 (without benzoquinone, BQ) to 0.042–0.443 min-1 at [BQ]o:[MnO4 ]o (molar ratio) = 0.03–0.25 at pH 7.5, and an acidic pH facilitated LF degradation. In the presence of BQ, MnO4 was first reduced to Mn(II). Then, Mn(II) reacted with BQ to produce Mn(III) and semiquinone radical, which was promoted under acidic conditions. With dissolved oxygen available, Mn(III) further oxidized semiquinone radical to produce singlet oxygen (1O2) and superoxide radical (O2 ) as well as regenerate BQ. In addition, MnO4 could also react with Mn(II) to produce Mn(III), whose complexation with semiquinone radical in turn promoted this reaction. Due to the predominant scavenging of O2 by BQ, 1O2 and Mn(III) mainly contributed to the accelerated LF degradation, with a notable formation of hydroxyl, ketone and endoperoxide groups in the degradation byproducts. This study helps better understand the role of natural organic matter in the degradation of organic micropollutants by MnO4 in water treatment.
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31711. 题目: Carbon dioxide, methane and nitrous oxide emissions from the human-impacted Seine watershed in France
文章编号: N18062302
期刊: Science of The Total Environment
作者: Audrey Marescaux, Vincent Thieu, Josette Garnier
更新时间: 2018-06-23
摘要: Greenhouse gas (GHG) emissions from rivers and lakes have been shown to contribute significantly to global carbon and nitrogen cycling. In temperate and human-impacted regions, simultaneous carbon dioxide, methane and nitrous oxide emissions from aquatic systems are poorly documented. We estimated carbon dioxide (CO2) concentrations in the Seine hydrosystem (71,730 km2, France) using direct measurements, and calculations of CO2 partial pressures from 14 field campaigns conducted between 2010 and 2017, and compared them to methane (CH4) and nitrous oxide (N2O) concentrations. In the main stem of the Seine River, CO2 showed the same spatial gradient as N2O and CH4 with peaks in concentration downstream from the arrival of effluents from wastewater treatment plants enriched in organic matter, thus favoring mineralization. It is likely that high CO2 concentrations upstream were due to organic carbon inputs from soils and enriched CO2 groundwater discharges, whereas high N2O and CH4 upstream values were likely due to denitrification in riparian wet areas and anoxic decomposition of organic matter-rich wetlands, respectively. In addition, seasonal variations in all three GHGs were observed with higher concentrations in summer when higher temperatures promote mineralization and low water reduces the dilution of organic matter mainly originating from WWTP effluents. GHG emissions were calculated and compared with agricultural and nonagricultural (urban, transport) fluxes in the basin. In the Seine River network, CO2 emissions dominated riverine GHG emissions, reaching 95.3%, while N2O and CH4 emissions accounted for 4.4% and 0.3%, respectively. These indirect emissions from the hydrosystem were estimated to account for 3.7% of the total GHG emissions from the basin that amounted to 61,284 Gg CO2eq yr-1. Comparatively, direct agricultural and nonagricultural GHG emissions were estimated at 23.3% and 73.0%., respectively.
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31712. 题目: Mapping soil organic matter in the Baranja region (Croatia): Geological and anthropic forcing parameters
文章编号: N18062301
期刊: Science of The Total Environment
作者: Igor Bogunovic, Sebastiano Trevisani, Paulo Pereira, Vesna Vukadinovic
更新时间: 2018-06-23
摘要: Spatial mapping of soil organic matter (SOM) and evaluation of the related natural and anthropic influencing factors are crucial to monitor the extent of degraded land and the evolution of soil functions. The objective of this work is to study the spatial distribution of SOM in a highly exploited agricultural area in the Baranja Region (Croatia). The spatially dense dataset available (4825 top-soil samples from 0 to 30 cm) allowed to produce reliable SOM maps using geostatistical interpolation kriging algorithms and to study the relationships with possible influencing factors. The interpolation has been conducted by means of two approaches. In one approach, the overall data set is considered for computing a global variogram and performing a direct interpolation of SOM values. In the second approach, the data are stratified according to two different geological and morphogenetic domains, Holocene Domain (HD) and Pleistocene Domain (PD), and a distinct geostatistical analysis is performed in each domain. The results showed that average SOM in the studied region was 2.29%, indicating a future need for adopting sustainable soil management practices in this region. SOM was significantly higher in HD (2.64%) than PD (1.97%) domain. SOM in PD generally had a much lower global variability. Global dataset analysis reveals that regional intrinsic factors prevail over local intrinsic and extrinsic factors in determining SOM spatial patterns. In contrast, the stratified approach can filter the effect of regional variability related to the main geological and geomorphological setting. The structural spatial correlation in PD is weaker than in HD, as manifested by spatial patches of low and high SOM content with smaller extension in PD with respect to HD. The strong relationships between SOM spatial patterns and geological/geomorphological factors suggest the possibility of adopting finer subdivision criteria in future research.
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31713. 题目: A model assessment of the role played by the carbonate (CO3?) and dibromide (Br2?) radicals in the photodegradation of glutathione in sunlit fresh- and salt-waters
文章编号: N18062204
期刊: Chemosphere
作者: Davide Vione
更新时间: 2018-06-22
摘要: Glutathione (GLU) is a peptidic thiol that plays important anti-oxidant roles in organisms and that occurs in both freshwater and seawater, where it can undergo both bio- and photodegradation. Recent results have elucidated the role played by OH, 1O2, H2O2 and other yet unidentified transients in GLU photochemistry, but very little is known of the role of CO3 -. This is an important gap because CO3 - is usually very reactive towards electron-rich compounds including thiols and mercaptans. Very little is also known on the environmental importance of the reaction between GLU and Br2 -, which could account for the literature finding that GLU phototransformation is enhanced in simulated seawater compared to freshwater. By means of a photochemical model approach based on the APEX software (Aqueous Photochemistry of Environmentally-occurring Xenobiotics), here we provide an assessment of the role that several photoreactants, including most notably CO3- and Br2 -, have in the photodegradation of GLU (both the whole substance and the separate neutral and mono-anionic species) under representative fresh- and saltwater conditions. Our model suggests that CO3 - would dominate the photodegradation of GLU in low-DOC and high-pH freshwater, which are the only freshwater conditions that really ensure GLU photodegradation to be competitive with biotransformation. This result supports the potential key importance of CO3 - in the environmental photochemistry of GLU. In surface seawater and in brackish water, GLU phototransformation might be dominated by the Br2 - reaction (the role of additional halogen species such as Cl2- and ClBr - is still unknown).
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31714. 题目: Evaluating the environmental parameters that determine aerobic biodegradation half-lives of pesticides in soil with a multivariable approach
文章编号: N18062203
期刊: Chemosphere
作者: Yuxin Wang, Adelene Lai, Diogo Latino, Kathrin Fenner, Damian E. Helbling
更新时间: 2018-06-22
摘要: Aerobic biodegradation half-lives (half-lives) are key parameters used to evaluate pesticide persistence in soil. However, half-life estimates for individual pesticides often span several orders of magnitude, reflecting the impact that various environmental or experimental parameters have on half-lives in soil. In this work, we collected literature-reported half-lives for eleven pesticides along with associated metadata describing the environmental or experimental conditions under which they were derived. We then developed a multivariable framework to discover relationships between the half-lives and associated metadata. We first compared data for the herbicide atrazine collected from 95 laboratory and 65 field studies. We discovered that atrazine application history and soil texture were the parameters that have the largest influence on the observed half-lives in both types of studies. We then extended the analysis to include ten additional pesticides with data collected exclusively from laboratory studies. We found that, when data were available, pesticide application history and biomass concentrations were always positively associated with half-lives. The relevance of other parameters varied among the pesticides, but in some cases the variability could be explained by the physicochemical properties of the pesticides. For example, we found that the relative significance of the organic carbon content of soil for determining half-lives depends on the relative solubility of the pesticide. Altogether, our analyses highlight the reciprocal influence of both environmental parameters and intrinsic physicochemical properties for determining half-lives in soil.

31715. 题目: A brief history of origins and contents of Organically Bound Tritium (OBT) and 14C in the sediments of the Rh?ne watershed
文章编号: N18062202
期刊: Science of The Total Environment
作者: Frédérique Eyrolle, Hugo Lepage, Yoann Copard, Loic Ducros, David Claval, Lionel Saey, Catherine Cossonnet, Franck Giner, David Mourier
更新时间: 2018-06-22
摘要: Tritium (3H) and Carbon-14 (14C) are radionuclides of natural (cosmogenic) origin that have also been introduced into the environment by humans since the middle of the last century. They are therefore not compounds that have only recently been released into the environment and they do not pose a recognized health threat due to their low radiotoxicity. However, they hold an important place among current concerns because they are being discharged into the environment by the nuclear industry in large quantities compared to other radionuclides. Those both radionuclides partly integrate organic matter during metabolic processes (i.e., photosynthesis) leading to organically bound forms that can be found in sediments. Organically bound tritium (OBT) analyses carried out on the sediments of the Rh ne and its tributaries indicate a significant and historical tritium labelling of sedimentary particles all along the Rh ne river, as well as in several northern tributaries, in particular the Ognon and the Tille rivers (tributaries of the Saone), the Doubs River and the Loue River (a tributary of the Doubs) and the Arve river. The recorded levels (10 to over 20,000 Bq/L) are very likely to be related to the presence of synthetic tritiated particles (technogenic tritium), which were used in the past in watchmaking workshops. Although overall contamination levels decrease from north to south in the Rh ne watershed and fade over time, particularly due to the radioactive decay of tritium, this contamination source of technogenic tritium in the Rh ne watersheds is currently still not negligible. Carbon-14 analyses show that the Rh ne sediments generally display 14C levels close to the atmospheric reference values (231 Bq·kg-1 of C in 2015) or even lower in most of cases, and show sporadic and weak labelling near nuclear facilities. The low 14C levels in the Rh ne sediments are most likely related to the solid contributions from tributaries draining areas that are rich in fossil organic matter, and therefore devoid of 14C. In the Rh ne watershed, the presence in solid particles of tritium in a form organically bound to synthetic compounds and of petrogenic (fossil) organic carbon, can potentially alter the apparent assimilation rates to the food chain of these two radionuclides.
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31716. 题目: Evaluation of anaerobic digestion of food waste and waste activated sludge: Soluble COD versus its chemical composition
文章编号: N18062201
期刊: Science of The Total Environment
作者: Yingqun Ma, Jun Gu, Yu Liu
更新时间: 2018-06-22
摘要: The hydrolysis as an essential step in anaerobic digestion has been commonly evaluated according to the extent of soluble chemical oxygen demand (SCOD) released from biosolids. However, little information is currently available for the effect of chemical compositions of SCOD on anaerobic digestion. This study showed that the non-biodegradable, recalcitrant organics in SCOD released from food waste and waste activated sludge pretreated with fungal mash rich in various enzymes were accumulated with the prolonged hydrolysis, while the methane production was closely related to the chemical compositions of the feed. The analyses by excitation emission matrix and size exclusion chromatography-organic carbon detection-organic nitrogen detection clearly revealed that the biodegradability of SCOD and the performance of anaerobic digestion were both determined by the chemical compositions of SCOD. These in turn challenged the present practice with SCOD concentration as a sole indicator in the selection and optimization of the pretreatment methods of biosolids prior to anaerobic digestion. It is expected that this study can offer useful insights into future design, optimization and operation of anaerobic digestion system in consideration of both SCOD concentration and its chemical compositions.
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31717. 题目: A novel flake-ball-like magnetic Fe3O4/γ-MnO2 meso-porous nano-composite: Adsorption of fluorinion and effect of water chemistry
文章编号: N18062105
期刊: Chemosphere
作者: Zhiwei Zhao, Cong Geng, Chun Yang, Fuyi Cui, Zhijie Liang
更新时间: 2018-06-21
摘要: A novel flake-ball-like magnetic Fe3O4/γ-MnO2 meso-porous nano-composite was synthesized and characterized for defluoridation. Adsorption process, characters, and effects of solution chemistry on the adsorption of flourinion in Fe3O4/γ-MnO2 were evaluated. The results show that the adsorption of fluorinion in the Fe3O4/γ-MnO2 nano-composite is fitted with the Pseudo-first model and the Langmuir model, indicating that the adsorption process of fluorinion in the Fe3O4/γ-MnO2 nano-composite was a physical process and not only controlled by the film diffusion but also controlled by the intra-particle diffusion and surface adsorption. It shows that the adsorption of fluorinion sharply decrease with the increase of pH due to the negative changed surface of Fe3O4/γ-MnO2 in water and the competition of OH for the active points. The competition from decreases the adsorption of fluoride in the order of Cl -< NO3 -< SO4 2-, which relied on the ratio of charge towards radius (z/r) of the anions, and the negatively charged humic acid competed with fluorinion for the adsorption sites. Based on the adsorption results and the XPS analysis, the OMn bond in the raw adsorbent supported the active site (OMnOH) for fluoride adsorption by forming an OMnF bond on the surface of Fe3O4/γ-MnO2.
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31718. 题目: Mechanistic consideration of the photochemical transformation of domoic acid (algal toxin) in DOM-Rich brackish water
文章编号: N18062104
期刊: Chemosphere
作者: Hangxing Jin, Lushi Lian, Huaxi Zhou, Shuwen Yan, Weihua Song
更新时间: 2018-06-21
摘要: Domoic acid (DA) is a neurotoxin generated by several diatom species in harmful algae blooms (HABs). We report the photo-induced transformation products (TPs) and degradation mechanisms of DA in dissolved organic matter (DOM)-rich freshwater and brackish water. High-resolution quadrupole time-of-flight mass spectrometry (QTOF-MS) and the multivariate statistical strategy orthogonal partial least-squares discriminant analysis (OPLS-DA) identified 36 and 23 potential TPs in DOM-rich freshwater and brackish water, respectively. The main reactive sites of DA are the conjugated double bond and proline ring. Isomerization is the predominant transformation pathway induced by excited-state triplet DOM (3DOM*). The second-order rate constant of the isomerization reaction was measured as (3.8 ± 0.2) × 108 M-1 s-1. The inverse correlation between the dissolved oxygen (DO) concentration and the rate of photo-induced DA isomerization was revealed. Furthermore, under halide-present conditions, halide radicals are mainly responsible for the differentiation of products by quenching hydroxyl radicals and generating unique organic peroxide products. Our results indicated that halide radicals could be important in the photochemical transformation of organic contaminants in high saline environments.
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31719. 题目: Direct and indirect photolysis of the antibiotic enoxacin: kinetics of oxidation by reactive photo-induced species and simulations
文章编号: N18062103
期刊: Environmental Science and Pollution Research
作者: Arlen Mabel Lastre-Acosta, Bruna Barberato, Marcela Prado Silva Parizi, Antonio Carlos Silva Costa Teixeira
更新时间: 2018-06-21
摘要: The purpose of this study was to investigate the aqueous phase photochemical behavior of enoxacin (ENO), an antibiotic selected as a model pollutant of emerging concern. The second-order reaction rate constants of ENO with hydroxyl radicals (HO●) and singlet oxygen (1O2) were determined at pH 3, 7, and 9. Also, the rate constants of the electron transfer reaction between ENO and triplet states of chromophoric dissolved organic matter (3CDOM*) are reported for the first time, based on anthraquinone-2-sulfonate (AQ2S) as CDOM proxy. The sunlight-driven direct and indirect ENO degradation in the presence of dissolved organic matter (DOM) is also discussed. The results show that direct photolysis, which occurs more rapidly at higher pH, along with the reactions with HO● and 3AQ2S*, is the key pathway involved in ENO degradation. The ENO zwitterions, prevailing at pH 7, show kENO, HO●, kENO,1O2, and kENO,3AQ2S* of (14.0 ± 0.8) × 1010, (3.9 ± 0.2) × 106, and (61.5 ± 0.7) × 108 L mol 1 s 1, respectively, whose differences at pH 3, 7, and 9 are due to ENO pH-dependent speciation and reactivity. These k values, along with the experimental ENO photolysis quantum yield, were used in mathematical simulations for predicting ENO persistence in sunlit natural waters. According to the simulations, dissolved organic matter and water depth are expected to have the highest impacts on ENO half-life, varying from a few hours to days in summertime, depending on the concentrations of relevant waterborne species (organic matter, NO3-, NO2-, HCO3-).

31720. 题目: Up-scaling of tannin-based coagulants for wastewater treatment: performance in a water treatment plant
文章编号: N18062102
期刊: Environmental Science and Pollution Research
作者: Kinga Grenda, Julien Arnold, José A. F. Gamelas, Maria G. Rasteiro
更新时间: 2018-06-21
摘要: Tannin extracts from the bark of Acacia mearnsii and wood of Schinopsis balansae, commonly known as Quebracho, were employed. These were modified at laboratory sale via the Mannich aminomethylation with formaldehyde and dimethylamine hydrochloride. Some reaction conditions were varied, namely the formaldehyde dosage and reaction time, while keeping the Mannich solution activation time constant, and their influence on the shear viscosity of the created bio-coagulants was evaluated. The effect of the final pH of the products on their shear viscosity was also analyzed. Up-scaling of the Mannich reaction for tannin from South Africa was performed and the procedure developed at 1-L scale was reproducible in upscaled conditions. One example of a modified South Africa tannin and the modified Quebracho tannin was subsequently selected for the treatment of an industrial wastewater and tested for color and turbidity reduction in jar tests. The effluent treatment was carried out in a single and dual system with cationic synthetic flocculation agents of different charge degree. Good turbidity and decoloration results (93 and 89% reduction, respectively) were obtained with the simultaneous introduction of a cationic, 40% charged polyacrylamide, with minimal dosage (5 ppm) of the latter additive. The tannin-based coagulant from Acacia mearnsii was successfully applied in dual system with cationic polyacrylamide flocculant for industrial wastewater treatment at pilot plant scale. It was shown to satisfactorily treat the water and generate less sludge.