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31481. 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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31482. 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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31483. 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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31484. 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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31485. 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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31486. 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.

31487. 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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31488. 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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31489. 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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31490. 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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31491. 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-).

31492. 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.

31493. 题目: Impact of organic matter types on surface charge and aggregation of goethite
文章编号: N18062101
期刊: Colloids and Surfaces A: Physicochemical and Engineering Aspects
作者: Stefan Dultz, Heiko Steinke, Robert Mikutta, Susanne K. Woche, Georg Guggenberger
更新时间: 2018-06-21
摘要: In order to assess the mobility and function of Fe oxihydroxides in terrestrial and aquatic environments, knowledge of the parameters and conditions determining aggregation and the size of formed aggregates is crucial. Here we study the impact of different organic matter (OM) types on the aggregation of goethite (α-FeOOH) with particular focus on the relevance of surface charge (SC). Synthetic goethite was reacted with galacturonic acid (GA), polygalacturonic acid (PGA), and tannic acid (TA) as model substances as well as with natural dissolved OM (DOM) from a litter (Oi-DOM) and a humified horizon (Oa-DOM). The SC of goethite was adjusted at pH 4 and 6 by the adsorption of organic acids and DOM to equal positive and negative SC as well as point of zero charge (pzc). Aggregation was traced by laser light scattering and sedimentation experiments. Aggregation of all goethite-OM associations depended on OM type and could well be explained by SC. Associations of goethite with OM rich in acidic groups (PGA, Oi-DOM, and Oa-DOM) followed the aggregation behavior of pure goethite. Largest aggregates with diameters up to 7 μm formed at pzc, whereas smaller ones ( 0.4 μm) developed at positive or negative SC. Organic substances rich in acidic functional groups interacted strongly with goethite at high additions, thus favoring charge reversal and limiting aggregate growth. For OM with low acidity (TA and GA), adsorption on goethite was incomplete even at high additions. These associations remained close to pzc and, hence, were susceptible to aggregation with maximum diameters at 6 μm. Aggregation was possibly also promoted by the exposure of less polar moieties exposed at the goethite-OM interface. Our data suggest that aggregation in environmental systems such as soils is driven by the nature and acidity of ubiquitous OM, which determines SC by the extent of adsorption to mineral surfaces.
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31494. 题目: Differences in long-term vs short-term carbon and nitrogen sequestration in a coastal river delta wetland: implications for global budgets
文章编号: N18062003
期刊: Organic Geochemistry
作者: R.D. DeLaune, J.R. White, T. Elsey-Quirk, H.H. Roberts, D.Q. Wang
更新时间: 2018-06-20
摘要: Coastal wetlands can serve as a considerable sink for carbon (C) gases. However, the capacity for wetlands to serve as more permanent C and N sinks over the long term is less clear given the time dependence of sediment deposition, organic matter decomposition, and anthropogenic land use change. In this study, we compare the short-term (decadal scale) and long-term (millennial scale) C and N accumulation rates estimated using 137Cs and radiocarbon dating of vibracores collected from a freshwater coastal wetland in the Louisiana Mississippi River deltaic plain (Atchafalaya River delta). The mean short-term (60 yr) sediment accumulation rate was 1.4 cm/yr while the mean rate of long-term (100–1000 yr) sediment accumulation was an order of magnitude lower at 0.12 cm/yr. Annual rates of C and N accumulated over the past several thousand years were approximately 10% of that over the past 60 years after correcting for bulk density. These results are similar to other coastal wetlands and suggest that time scale must be considered in determining the relative permanence of C and N storage in coastal wetland soils. This difference is especially important for assessing the role of C cycling in relation to global change models and N cycling related to water quality in accurately quantifying the role of coastal deltaic fresh water wetlands in regulating these biogeochemical cycles.
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31495. 题目: Biochar from Different Carbonaceous Waste Materials: Ecotoxicity and Effectiveness in the Sorption of Metal(loid)s
文章编号: N18062001
期刊: Water, Air, & Soil Pollution
作者: Mariano Simón, Inés García, María Diez-Ortiz, Verónica González
更新时间: 2018-06-20
摘要: In this study, biochar produced by pyrolysis of urban pruning wood (Bpw) and sewage sludge (Bss) were characterized and investigated as adsorbents for the removal of Cu(II), Pb(II), Zn(II), and As(V) from contaminated solutions. Both types of biochars showed different physical-chemical properties and metal(loid) content. In Bss, Cu, Zn, and Pb concentrations exceeded the upper limit of the common ranges in soils. However, when they were tested for their effect on soil invertebrates, neither of the biochar was expected to exert negative effects as long as the dose applied as an amendment was ≤ 4.8 t ha-1. For an assessment of the effectiveness of biochar in the immobilization of metal(loid)s, three contaminated solutions with acidic pH and different pollutant concentrations were added to both types of biochar. Precipitation as oxy-hydroxides and the formation of complexes with active functional groups of the organic matter were the main mechanisms of metal(loid) fixation by the biochar, with increased precipitation and a rising pH. Both types of biochar were effective at immobilizing Pb and Cu, while Zn showed less effectiveness in this regard and As the least. The high P content of the biochar from sewage sludge favored Pb fixation, presumably forming complexes with phosphates, while competition between phosphate and arsenate ions decreased As adsorption by Fe compounds. The metal(loid)s immobilized by biochar from urban pruning wood were more bioavailable

31496. 题目: Tillage system change affects soil organic carbon storage and benefits land restoration on loess soil in North China
文章编号: N18061906
期刊: Land Degradation & Development
作者: HaoWang , ShulanWang , YujiaoZhang , XiaoliWang , RuiWang , JunLi
更新时间: 2018-06-19
摘要: Soil organic carbon (SOC) is a core indicator of soil quality. A proper tillage system can improve SOC accumulation and benefit land restoration. This improvement is especially significant in loess soil, which is undergoing serious degradation in China. In this study, we chose a field that was used for crop production and used a traditional moldboard plow with crop residue removal (CT) for over 10 years. We then carried out a long‐term field experiment (2007–2015) and changed the tillage system from a moldboard plow with crop residue removal to either a moldboard plow with buried straw system (BT), a no‐tillage with straw mulch system (NT), or a subsoiling with straw mulch system (ST) to evaluate the effect of tillage system change and the effects of tillage systems on SOC storage. Tillage system change influenced SOC content, NT, ST, and BT showed higher values of SOC content and increased 8.34, 7.83, and 1.64 Mg·C·ha 1, respectively, compared with CT. Among the 3 changed tillage systems, NT and ST showed a 12.5% and 11.6% increase in SOC content then BT, respectively. Tillage system change influenced SOC stratification ratio values, with higher value observed in BT and NT compared CT but ST. Therefore, in loess soil, changing tillage system can significantly improve SOC storage and change profile distribution. The NT and ST treatments showed a more marked SOC increase, but the increase value in stratification ratio with NT still needs attention, and our results is meaningful for soil quality improvement and land restoration.

31497. 题目: Ferrate(VI) oxidation of polychlorinated diphenyl sulfides: Kinetics, degradation, and oxidized products
文章编号: N18061905
期刊: Water Research
作者: Jing Chen, Xinxin Xu, Xiaolan Zeng, Mingbao Feng, Ruijuan Qu, Zunyao Wang, Nasri Nesnas, Virender K. Sharma
更新时间: 2018-06-19
摘要: This paper presents oxidation of polychlorinated diphenyl sulfides (PCDPSs), dioxin-like compounds, by ferrate(VI) (FeVIO4 2 , Fe(VI)). Kinetics of the reactions of Fe(VI) with seventeen PCDPSs, differ in number and positions of chlorine atoms (from 2 to 7), were investigated at pH 8.0. The second-order rate constants (k, M 1 s 1) of the reactions varied with the numbers and positions of chlorine atoms and appeared to be related with standard Gibbs free energy of formation (ΔfG0) of PCDPSs. Degradation experiments in the presence of ions and humic acid demonstrated complete removal of PeCDPS by Fe(VI) in minutes. Pathways of the reaction were investigated by identifying oxidized products (OPs) of the reaction between Fe(VI) and 2,2′,3’,4,5-pentachlorodiphenyl sulfide (PeCDPS) at pH 8.0. Pathways of oxidation involved major pathway of attack on sulfur(II) by Fe(VI) in steps to yield sulfoxide type products, and subsequent breakage of C-S bond with the formation of sulfonic acid-containing trichloro compound. Minor pathways were hydroxylation of benzene ring and substitution of chlorine atom with hydroxyl group. Estimation of toxicity of OPs of the oxidation of PeCDPS by Fe(VI) suggested the decreased toxicity from the parent contaminant.
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31498. 题目: Impact of chlorination on silver elution from ceramic water filters
文章编号: N18061904
期刊: Water Research
作者: Bonnie A. Lyon-Marion, Anjuliee M. Mittelman, Justine Rayner, Daniele S. Lantagne, Kurt D. Pennell
更新时间: 2018-06-19
摘要: Applying silver nanoparticles (nAg) or silver nitrate (AgNO3) to ceramic water filters improves microbiological efficacy, reduces biofilm formation, and protects stored water from recontamination. A challenge in ceramic filter production is adding sufficient silver to achieve these goals without exceeding the maximum recommended silver concentration in drinking water. Silver release is affected by silver type, application method, and influent water chemistry. Despite a lack of data, there is an assumption that chlorinated water should not be used as influent water because it may increase silver elution. Thus, the objective of this work was to systematically evaluate the impact of chlorinated water (0–4 mg/L free chlorine residual, FCR) on silver release from ceramic filter disks painted with casein-coated nAg, painted with AgNO3, or containing fired-in nAg over a range of ionic strength (IS = 0–10 mM as NaNO3) in the presence or absence of natural organic matter (NOM). Influent deionized water containing chlorine increased silver release 2–5-fold compared to controls. However, this effect of chlorine was mitigated at higher IS (≥1 mM) or in the presence of NOM (3 mg C/L). For filter disks painted with nAg or AgNO3, silver release increased with increasing IS (with or without chlorine), and effluent concentrations remained above the World Health Organization (WHO) guideline of 0.1 mg/L even after 30 h (80 pore volumes, PVs) of flow with a background solution of 10 mM NaNO3. Silver speciation (nAg vs. Ag+) was monitored in effluent samples from painted or fired-in nAg filter disks. Results indicated that in general, greater than 90% of the eluted silver was due to Ag+ dissolution rather than nAg release. Additionally, a filter disk prepared with fired-in nAg exhibited a lower % released in the nanoparticle form (nAg = 5% of total Ag in effluent) compared to painted on nAg (nAg = 14% of total Ag in effluent). The findings of this study suggest that chlorinated influent water has minimal impact on silver elution from ceramic filters under simulated natural water conditions, and thus, the recommendation to avoid the use of chlorinated water with ceramic filters is not necessary under most conditions.
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31499. 题目: Insights into the simultaneous removal of Cr6+ and Pb2+ by a novel sewage sludge-derived biochar immobilized nanoscale zero valent iron: Coexistence effect and mechanism
文章编号: N18061903
期刊: Science of The Total Environment
作者: Zeng-Hui Diao, Jian-Jun Du, Dan Jiang, Ling-Jun Kong, Wen-Yi Huo, Cui-Mei Liu, Qi-Hang Wu, Xiang-Rong Xu
更新时间: 2018-06-19
摘要: Cr6+ and Pb2+ are both highly toxic pollutants and commonly co-exist in some industrial effluents and contaminated waters. In this study, simultaneous removal of Cr6+ and Pb2+ by a novel sewage sludge-derived biochar immobilized nanoscale zero-valent iron (SSB-nZVI) was systematically investigated. It was well demonstrated that a porous structure was successfully formed on the SSB-nZVI when the starch was used as an additive. A synergistic effect on the adsorption and reduction over the SSB-nZVI was achieved, resulting in nearly 90 and 82% of Cr6+ and Pb2+ removal within 30 min, respectively. Cr6+ was reduced prior to Pb2+. A low pH could accelerate the corrosion of nZVI as well as phosphate leaching. When Malachite green was added as a coexisting organic pollutant, its effective removal was found due to the formation of a Fenton-like system. The SSB-nZVI could be run consecutively three times with a relatively satisfactory performance. Most of Cr6+ was converted into Cr2O3 and Cr(OH)3 on the SSB-nZVI surface, whereas most of Pb2+ species existed as Pb(OH)2 (or PbO). A possible reaction mechanism on the SSB-nZVI involved the adsorption, reduction and precipitation of both Cr6+ and Pb2+ over the particles. Present study sheds light on the insight of the fate and transport of Cr6+ and Pb2+ in aquatic environment, as well provides helpful guide for the remediation of coexistence of pollutants in real applications.
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31500. 题目: Humic-Like Substances (HULIS) in Aerosols of Central Tibetan Plateau (Nam Co, 4730 m asl): Abundance, Light Absorption Properties, and Sources
文章编号: N18061902
期刊: Environmental Science & Technology
作者: Guangming Wu, Xin Wan, Shaopeng Gao, Pingqing Fu, Yongguang Yin, Gang Li, Guoshuai Zhang, Shichang Kang, Kirpa Ram, Zhiyuan Cong
更新时间: 2018-06-19
摘要: Humic-like substances (HULIS) are major components of light-absorbing brown carbon that play an important role in Earth’s radiative balance. However, their concentration, optical properties, and sources are least understood over Tibetan Plateau (TP). In this study, the analysis of total suspended particulate (TSP) samples from central of TP (i.e., Nam Co) reveal that atmospheric HULIS are more abundant in summer than that in winter without obvious diurnal variations. The light absorption ability of HULIS in winter is 2–3 times higher than that in summer. In winter, HULIS are mainly derived from biomass burning emissions in South Asia by long-range transport. In contrast, the oxidation of anthropogenic and biogenic precursors from northeast part of India and southeast of TP are major sources of HULIS in summer.
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