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24581. 题目: Application of DGT/DIFS and geochemical baseline to assess Cd release risk in reservoir riparian soils, China
文章编号: N18080305
期刊: Science of The Total Environment
作者: Dongyu Xu, Bo Gao, Wenqi Peng, Li Gao, Xiaohong Wan, Yanyan Li
更新时间: 2018-08-03
摘要: As the sole drinking water source for Beijing City, Cd has been previously assessed as the major contaminant in Miyun Reservoir (MYR) riparian soils. However, the potential release risk of Cd in such soils, and the labile-Cd release–resupply process from the soil solid phase to solution after water impoundment remain poorly understood. We established a geochemical baseline concentration (GBC) of Cd in MYR riparian soils, combined with the diffusive gradient in thin films (DGT) technique and DGT-induced fluxes in soil (DIFS) model, to reveal a dynamic release–resupply process and influencing factors of labile Cd in riparian soils. The results showed that Cd GBC in riparian soils was 0.12 mg/kg, which was higher than the Cd background value (BV) for Beijing. Using Cd GBC as BV to assess the Cd contaminant level, the geo-accumulation index showed that Cd in riparian soils was at the uncontaminated level. In addition, Cd in the soils belonged to the non-residual fraction using the Community Bureau of Reference method. Cd mobility coefficients (F1/C_Total-Cd) of soils at low elevation had relatively high values, implying that Cd may be released during the initial impoundment of the MYR. Moreover, correlation analysis was used to found the major influencing factors between DGT-labile Cd and several parameters. The results showed that the DGT-labile Cd was positively correlated to the reducible and oxidizable fraction, C_DGT-Fe, and total organic carbon, illustrating that the release of Cd from soils was controlled by Fe oxides and organic matter. The resupply ability (R values) and DIFS model parameters revealed that Cd in MYR soils belonged to the partially sustained case, and the slow desorption rate suggested that the release risk of Cd was low in the MYR riparian soils.
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24582. 题目: Dynamic molecular size transformation of aquatic colloidal organic matter as a function of pH and cations
文章编号: N18080304
期刊: Water Research
作者: Huacheng Xu, Hui Lin, Helong Jiang, Laodong Guo
更新时间: 2018-08-03
摘要: Knowledge of the dynamic changes in molecular size of natural colloidal organic matter (COM) along the aquatic continuum is of vital importance for a better understanding of the environmental fate and ecological role of dissolved organic matter and associated contaminants in aquatic systems. We report here the pH- and cation-dependent size variations of COMs with different sources (river and lake) quantified using flow field-flow fractionation (FIFFF), fluorescence spectroscopy and parallel factor analysis (PARAFAC), attenuated total reflectance Fourier transform infrared (ATR–FTIR) spectroscopy, and zeta potential analysis. Increasing pH caused a decline in molecular sizes and an obvious size transformation from the >10 kDa to 5–10 kDa and further to 1–5 kDa size fraction, whereas the opposite trend was observed for increasing cation (e.g., Ca²⁺ and Cu²⁺) abundance. Compared with lakewater COM, the riverwater COM exhibited a greater pH-dependent dispersion but less extent in cation-induced aggregation, demonstrating that the dispersion and aggregation dynamics were highly dependent on COM source and solution chemistry (e.g., pH and cations). Based on ATR–FTIR analysis, the extensive dissolution of C=O and C–O functional groups resulted in a greater pH-dependent dispersion for river COM. Fluorescence titration revealed that, despite their similar cation-induced aggregation behavior, the binding constants of all the PARAFAC-derived components for Cu²⁺ were 1–2 orders of magnitude higher than those for Ca²⁺ (logK_M: 4.54–5.45 vs. 3.35–3.70), indicating a heterogeneous nature in cation-DOM interactions. The greater extent of decline in zeta potential for lake COM suggested a Ca-induced charge neutralization and aggregation mechanism. However, for Cu-induced aggregation, chemical complexation was the predominant pathway for the river COM, with higher binding constants, while charge neutralization and chemical complexation co-induced the aggregation of lake COM. Thus, natural COMs may have different environmental behavior along the aquatic continuum and further affect the fate and transport of contaminants in aquatic environments.
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24583. 题目: Charge-Assisted Hydrogen Bonding as a Cohesive Force in Soil Organic Matter: Water Solubility Enhancement by Addition of Simple Carboxylic Acids
文章编号: N18080303
期刊: Environmental Science: Processes Impacts
作者: Jinzhi Ni, Joseph J. Pignatello
更新时间: 2018-08-03
摘要: Weak bonds between molecular segments and between separate molecules of natural organic matter (OM) govern its solubility, adsorption, supramolecular association in solution, and complexation with metal ions and oxides. We tested the hypothesis that especially strong hydrogen bonds, known as (negative) charge-assisted hydrogen bonds, (-)CAHB, contribute significantly to OM cohesion and increase water solubility of solid-phase OM. The (-)CAHB, exemplified by structures such as (CO2HO2C) and (CO2HO), may form between weak acids with similar proton affinity, and is shorter, more covalent, and much stronger than ordinary hydrogen bonds. Using a high-organic reference soil, we show that (-)CAHBs within the solid OM phase (intra-OM) are disrupted by solutions of aliphatic and aromatic acids, resulting in enhanced solubility of OM. The aromatic acids included naturally occurring plant exudate compounds. At constant pH and ionic strength, OM solubility increased with added organic acid concentration and molecular weight. Polar compounds incapable of forming (-)CAHBs, such as alkanols, acetonitrile, and dimethyl sulfoxide, were ineffective. Solubility enhancement showed behavior consistent with (-)CAHB theory and published observations—namely, i) that formate is more effective than acetate due to its tendency to form stronger (-)CAHBs; ii) that solubility enhancement peaks at pH ~5-6, where the product of interacting carboxylate ion concentrations reaches a maximum; and iii) that elution of acetate or formate through soil columns releases hydroxide ion, consistent with formation of (-)CAHBs between added acid and free weak acid groups on the solid OM. The results support the hypothesis that the (-)CAHB contributes to the cohesion of OM in the solid state.

24584. 题目: Biochar stability assessment methods: A review
文章编号: N18080302
期刊: Science of The Total Environment
作者: Lijian Leng, Huajun Huang, Hui Li, Jun Li, Wenguang Zhou
更新时间: 2018-08-03
摘要: Biochar is being developed as a candidate with great potential for climate change mitigation. Sequestering biochar carbon in soil contributes greatly to the reduction of greenhouse gases emissions, and biochar stability is the most decisive factor that determines its carbon sequestration potential. However, methods that can be used universally for direct or indirect assessment of biochar stability are still under investigation. This present review aims to give comprehensive and detailed up-to-date information on the development of biochar stability assessment methods. The method details, advantages and disadvantages, along with the correlations between different methods were reviewed and discussed.
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24585. 题目: Hybrid organic-inorganic functionalized polyethersulfone membrane for hyper-saline feed with humic acid in direct contact membrane distillation
文章编号: N18080301
期刊: Separation and Purification Technology
作者: Aftab Ahmad Khan, Muhammad Irfan Siyal, Chang-Kyu Lee, Chansoo Park, Jong-Oh Kim
更新时间: 2018-08-03
摘要: In this study, hybrid organic-inorganic functionalized polyethersulfone (PES) membrane was prepared for treating hyper-saline feed solutions containing humic acid (HA) foulant. The membrane modification was carried out by dip-coating with silica nanoparticles, followed by vacuum filtration coating with 1H,1H,2H,2H-perfluorodecyl triethoxysilane and polydimethylsiloxane. The membranes were characterized by field emission scanning electron microscope, atomic force microscope, Fourier transform infrared, and thermal gravimetric analyses. The evaluation of membranes with water contact angle, liquid entry pressure, direct contact membrane distillation (DCDM), and stability tests, proved the durable amphiphobic nature of the modified PES membrane (PDMS-FAS/SiNPs). The membrane performance was respectively better from that of commercial polypropylene (PP) and polyvinylidene fluoride (PVDF) membranes. In the DCMD of a feed solution of 1 M NaCl and 10 mg L^-1 HA, the flux of the PDMS-FAS/SiNPs membrane remained consistent (17 LMH), with a permeate conductivity of 33.96 µS cm^-1. The optimized modified membrane showed better performance in terms of permeate flux, salt rejection, and anti-fouling behavior in DCMD. These wonderful results of functionalized PDMS-FAS/SiNPs PES membrane are attributed to the step-wise simple, and inexpensive dip-coating followed by vacuum filtration coating using efficient hybrid organic-inorganic material combination.
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24586. 题目: Influence of Biochar Addition on Nitrogen Transformation during Copyrolysis of Algae and Lignocellulosic Biomass
文章编号: N18080211
期刊: Environmental Science & Technology
作者: Wei Chen, Haiping Yang, Yingquan Chen, Kaixu Li, Mingwei Xia, Hanping Chen
更新时间: 2018-08-02
摘要: Algae are extremely promising sustainable feedstock for fuels and chemicals, while they contain high nitrogen content, which may cause some serious nitrogen emission during algae pyrolysis utilization. In this study, we proposed a feasible method to control the nitrogen emission during algae pyrolysis by introducing lignocellulosic biomass and biochar addition. Nitrogen transformation mechanism was investigated through quantitative analysis of N-species in the pyrolysis products. Results showed that copyrolysis of algae and lignocellulosic biomass greatly increased nitrogen in solid char with large amount of NH₃ and HCN releasing (∼20 wt %), while nitrogen in bio-oil decreased largely. With biochar addition, NH₃, HCN, and N-containing intermediates (amines/amides and nitriles) reacted with higher active O-species (O—C═O, −OH, and −COOH) in biochar addition, and formed large amounts of amine/amide-N, pyridinic-N, pyrrolic-N, and quaternary-N on the surface of biochar addition, which led to most nitrogen being enriched in char product and biochar addition (over 75 wt %) at the expense of amines/amides, nitriles, and N-containing gas (only 3 wt % NH₃ and HCN emission; decrease of 85%). These results demonstrated that biochar addition showed a positive influence on fixation of N-species during thermochemical conversion of algae and could convert nitrogen to valuable N-doped biochar materials.
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24587. 题目: Immobilized microalgae for anaerobic digestion effluent treatment in a photobioreactor-ultrafiltration system: Algal harvest and membrane fouling control
文章编号: N18080210
期刊: Bioresource Technology
作者: Binghan Xie, Weijia Gong, Huarong Yu, Xiaobin Tang, Zhongsen Yan, Xinsheng Luo, Zhendong Gan, Tianyu Wang, Guibai Li, Heng Liang
更新时间: 2018-08-02
摘要: A photobioreactor (PBR) coupled with ultrafiltration (UF) system was developed with goals of microalgae cultivation, harvest, and membrane fouling control in the anaerobic digestion effluent purification. Firstly, three-sequencing batch PBRs were started-up with suspended Chlorella vulgaris (C. vulgaris, SCV), immobilized C. vulgaris (ICV) and immobilized C. vulgaris with powdered activated carbon (ICV + PAC). The results exhibited high DOC degradation (66.61%–84.35%) and completely nutrients (nitrogen and phosphorus) removals were attained in PBRs. This indicated bacterial-microalgal consortiums enhanced biodegradation and PAC adsorption accelerated photodegradation. During the microalgae harvest by UF, immobilized microalgae beads protected cells integrity with less debris and intracellular/extracellular organic matters lysis. Moreover, the cake layer in ICV + PAC could even serve as a dynamic layer to entrap the residual pollutants and control membrane fouling. Hence, membrane fouling mitigation and ADE purification were realized during the microalgae harvest process in the ICV + PAC.
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24588. 题目: Lignin-induced growth inhibition in soybean exposed to iron oxide nanoparticles
文章编号: N18080209
期刊: Chemosphere
作者: Tamires Letícia Cunha Lopes, Rita de Cássia Siqueira-Soares, Guilherme Henrique Gonçalves de Almeida, Gabriele Sauthier Romano de Melo, Gabriela Ellen Barreto, Dyoni Matias de Oliveira, Wanderley Dantas dos Santos, Osvaldo Ferrarese-Filho, Rogério Marchiosi
更新时间: 2018-08-02
摘要: Plants are occasionally exposed to environmental perturbations that limit their growth. One of these perturbations is the exposure to and interaction with various nanoparticles (NPs) that are discarded continuously into the environment. Hitherto, no study has been carried out evaluating the effects of iron oxide (γ-Fe₂O₃) NPs on soybean growth and lignin formation, as proposed herein. For comparative purposes, we also submitted soybean plants to non-nanoparticulate iron (FeCl₃). Exposure of the plants to γ-Fe₂O₃ NPs increased cell wall-bound peroxidase (POD) activity but decreased phenylalanine ammonia lyase (PAL) activity due, probably, to the negative feedback of accumulated phenolic compounds. In contrast, FeCl₃ decreased cell wall-bound POD activity. Both γ-Fe₂O₃ NPs and FeCl₃ increased the lignin content of roots and stems. However, significant lignin-induced growth inhibition was noted only in stems after exposure to NPs, possibly due to changes in lignin monomer composition. In this case, γ-Fe₂O₃ NPs decreased the guaiacyl monomer content of roots but increased that of stems. The high levels of monomer guaiacyl in stems resulting from the action of γ-Fe₂O₃ NPs decreased syringyl/guaiacyl ratios, generating more highly cross-linked lignin followed by the stiffening of the cell wall and growth inhibition. In contrast, FeCl₃ increased the contents of monomers p-hydroxyphenyl and syringyl in roots. The observed increase in the syringyl/guaiacyl ratio in plant roots submitted to FeCl₃ agrees with the lack of effect on growth, due to the formation of a less condensed lignin. In brief, we here describe that γ-Fe₂O₃ NPs and FeCl₃ act differently in soybean plants.
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24589. 题目: Winter road management effects on roadside soil and vegetation along a mountain pass in the Adirondack Park, New York, USA
文章编号: N18080208
期刊: Journal of Environmental Management
作者: Hanna M. Willmert, Joseph D. Osso, Michael R. Twiss, Tom A. Langen
更新时间: 2018-08-02
摘要: In 2003-2005, we resurveyed and expanded plots surveyed in 1985 to examine the cumulative impact of road salt (sodium chloride) and sand along a two-lane highway in the Adirondack State Park in New York State (USA). Annual salt applications in the period 1985-2005 ranged from 50 tonnes per centerline-km (1985) to 140 tonnes (2005) and sand applications ranged from nearly zero tonnes (2005) to 325 tonnes (1985). Roadside soils and vegetation were significantly impacted by salt deposition compared to soils and vegetation 30 meters and 150 meters from the road. Roadside soil contained more sand, less organic matter, had a lower cation exchange capacity, was denser, and retained less water than soils 30 m and 150 m from the road. The concentration of sodium in roadside soils was elevated (103 vs. 44 ppm in soil 150 m from the roadside), and roadside concentrations of plant-nutritive cations were lower than 150 m from the road (roadside Mg, Ca and K concentrations were 0.2, 5, and 1 ppm respectively vs. 23,168, and 30 ppm at 150 m from the road). Along the roadside, paper birch trees (Betula papyrifera) and other woody vegetation present in 1980 were absent in 2004, suggesting that survival and recruitment of paper birch trees was impacted by degradation of soil fertility, deposition of road salt and aerosolization of salt from the roadway. Roadside environmental degradation caused by winter road management has worsened since 1980; revegetation with native salt-tolerant plants may provide some mitigation of the most severe effects. Overall, we conclude that the full extent of roadside environmental degradation caused by winter road management can take decades to manifest, and this may be the case more generally along cold-climate montane roadways.

24590. 题目: Steroid fingerprints: efficient biomarkers of human decomposition fluids in soil
文章编号: N18080207
期刊: Organic Geochemistry
作者: Barbara von der Lühe, Jago J. Birk, Lorna Dawson, Robert W. Mayes, Sabine Fiedler
更新时间: 2018-08-02
摘要: The decomposition of animal and human cadavers can lead to comprehensive chemical and biochemical changes in soil, which can provide helpful information for the analysis of archaeological and crime scenes. The current study focused specifically on the concentration and distribution patterns of steroids in soil with the aim of assessing their suitability for demonstrating the presence of human decomposition products. Soil samples were collected from a forensic site where a human corpse had been lying on the soil surface for 18 days. Total organic carbon (TOC) and steroid concentrations were analysed in soil samples taken from beneath the body at the time the corpse was removed and also one year later. High concentrations of TOC and steroids were detected close to the soil surface at the time the body was removed, and the concentration of cadaver-derived cholesterol was considerably higher than that of the plant-derived sitosterol. The soil beneath the cadaver contained higher concentrations of faeces-derived 5β-stanol coprostanol than the control soil. Different concentrations and distribution patterns of steroid compounds in the soil upon removal of the corpse and one year later indicate that significant transformation, degradation and translocation processes had taken place during this period of time. The depth distribution of steroids beneath a decomposing body along with changes in the human steroidal fingerprints in soil over time were found to provide information that could help resolve forensic and archaeological issues. The combined analysis of tissue steroids (cholesterol), the reduction product of cholesterol in soil (5α-cholestanol) as well as faecal steroids (coprostanol, 5β-stigmastanol and their conversion products epicoprostanol and epi-5β-stigmastanol) represent excellent additions to the forensic toolbox for determining whether a soil of interest has ever been affected by a human cadaver or not.

24591. 题目: Radically different lignin composition in Posidonia species may link to differences in organic carbon sequestration capacity
文章编号: N18080206
期刊: Organic Geochemistry
作者: Joeri Kaal, Oscar Serrano, José C. del Río, Jorge Rencoret
更新时间: 2018-08-02
摘要: There is considerable variability in the ability of seagrass ecosystems to sequester organic carbon (C_org) in their sediments, which act as natural carbon sinks contributing to climate change mitigation. In this work, we studied the chemistry of two Posidonia seagrass species aiming to elucidate whether differences in chemical composition might explain differences in their C_org sequestration capacity. Pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) and Thermally assisted Hydrolysis and Methylation (THM) GC-MS data showed a remarkable difference in phenolic compound patterns between P. oceanica and P. australis bulk plants and individual organs (leaves, sheaths, roots and rhizomes). The lignin of P. australis generates a series of p-hydroxyphenyl (H), guaiacyl (G) and syringyl (S) products that are typical of herbaceous plants, whereas P. oceanica is particularly rich in p-hydroxybenzoic acid (pBA) derivatives. The structural characteristics of the lignins were further investigated by two-dimensional Nuclear Magnetic Resonance (2D-NMR) and Derivatization Followed by Reductive Cleavage (DFRC), focusing on sheath tissues. The analyses confirmed important differences in the lignin content (19.8% in P. australis and 29.5% in P. oceanica) and composition between the two species; intriguingly, the cell-walls of P. oceanica sheaths were highly enriched in pBA, a component that was completely absent in P. australis. 2D-NMR and DFRC further revealed that pBA was esterified to the lignin, acylating the γ-OH of the lignin side-chain. Interestingly, P. oceanica lignin presented an extremely high degree of p-hydroxybenzoylation in both guaiacyl (73%) and syringyl (61%) lignin units, the highest p-hydroxybenzoylation degree reported in plant lignins to date. It is tempting to conclude that the higher soil C_org storage capacity of P. oceanica ecosystems might be related to the higher abundance of pBA-rich lignin and its recalcitrant nature.

24592. 题目: Depositional environment of the Late Santonian lacustrine source rocks in the Songliao Basin (NE China): Implications from organic geochemical analyses
文章编号: N18080205
期刊: Organic Geochemistry
作者: Xiaoning Tong, Jianfang Hu, Dangpeng Xi, Mengbo Zhu, Jianzhong Song, Ping'an Peng
更新时间: 2018-08-02
摘要: The Songliao Basin (SLB) located in northeastern China is one of the largest Cretaceous continental sedimentary basins in the world. The SLB is filled with sediments deposited in the Upper Jurassic, the Lower Cretaceous and the Upper Cretaceous epochs. The Nenjiang Formation (K₂n) is subdivided into five members, where Member 2 (K₂n²) was deposited in the late Santonian in the lower part of the Nenjiang Formation. This member is characterized by a thick succession of organic-rich source rocks. However, the complexity of the depositional environment raises questions about the specific factors that drove this accumulation of organic material. Here, we present data on the total organic carbon (TOC) contents and their stable carbon isotope values (δ¹³C_org), as well as biomarker data from 50 outcrop samples collected from the Yuewangcheng (YWC) section, in the southeastern SLB. According to the variations of the bulk organic parameters (TOC and δ¹³C_org) and biomarker indices, the profile could be divided into three stages (stages I–III). The distribution of biomarkers (n-alkanes, steranes and hopanes) and δ¹³C_org values indicate that the organic matter (OM) in the Lower K₂n² is derived largely from algae and macrophytes, with a minor input from bacteria and land plants. The water column was stratified, as indicated by the presence of gammacerane. Variations in the pristane/phytane (Pr/Ph) and aryl isoprenoids relative to phenanthrene ratio (A-i/P) suggest that bottom waters were anoxic during Stage I (31.5–26.0 m) and Stage II (26.0–16.3 m), with the anoxic layer impinging on the euphotic zone and a relative oxic environment at Stage III (16.3–0 m). This brackish environment persisted in the water over the interval represented by the section, as reflected by methytrimethyltridecyl chromans (MTTCs) Index (MTTCI) and α-MTTC/γ-MTTC ratios. Marine transgressions, with subsequent seawater incursions, can be detected with the presence of 24-n-propyl-cholestanes and 24-iso-propyl-cholestanes in the Lower K₂n² sediments, especially during Stage I. These seawater incursions are closely correlated with anoxic conditions and the deposition of organic-rich source rocks.

24593. 题目: Effect of salinity on the decomposition of soil organic carbon in a tidal wetland
文章编号: N18080204
期刊: Journal of Soils and Sediments
作者: Wendi Qu, Juanyong Li, Guangxuan Han, Haitao Wu, Weimin Song, Xiaoshuai Zhang
更新时间: 2018-08-02
摘要: Purpose: Climate warming and sea level rise have the potential to change the salt level of soil in tidal wetlands. And it is important to clarify the process and the mechanism of decomposition of soil organic carbon in a tidal wetland under varying salinities. The aim of this study was to evaluate the impacts of soil salinity on the decomposition rate of organic carbon (DROC) and dissolved organic carbon (DOC) in a tidal wetland. Materials and methods: Two types of soil (surface soil in Suaeda salsa and bare tidal flat) were collected, air-dried, and homogenized. After adding different content of salt (0 g/L, 3 g/L, 6 g/L, 9 g/L, and 12 g/L), the soils were incubated for 28 days at stable room temperature (25 ± 2 °C) and added by deionized water to maintain the stability of soil moisture. The gases (CO₂ and CH₄) emission rates of each salt treatment were measured during 28-day incubation. DROC was determined by the sum of daily CO₂-C emission rates and daily CH₄-C emission rates in this study. Results and discussion: Salt addition inhibited the process of gas emissions and DROC. Gases emission rates and DROC of two types of soil showed similar temporal trends, with distinctive drop in the beginning of experiment and no significant decrease followed. Significant difference of DOC among salt treatments was found in the bare tidal flat soil. Variations of partial correlation between DROC and soil salinity and DOC showed similar trends (e.g., in days 9–18, the positive effect of DOC on DROC was greatly promoted (R² = 0.80, p < 0.001), and the negative effect of soil salinity was highly improved (R² = 0.93, p < 0.001)). Soil properties, in particular DOC, may be primary factors accounting for the discrepancy of gases emission rates and DROC of two types of soil. Conclusions: Increased soil salinity had a negative effect on DROC during 28-day incubation. The impact of soil salinity and DOC on DROC were varied in different phases of laboratory experiment (soil salinity generally had increasingly negative relationship with DROC, but DOC showed most significantly positive relationship in the middle stage of incubation). Both the formation and consumption of DOC may be valuable for more detail research regarding to decomposition of soil organic carbon.

24594. 题目: Distribution, dynamics and determinants of antibiotics in soils in a peri-urban area of Yangtze River Delta, Eastern China
文章编号: N18080203
期刊: Chemosphere
作者: Fangkai Zhao, Liding Chen, Lei Yang, Shoujuan Li, Long Sun, Xinwei Yu
更新时间: 2018-08-02
摘要: Antibiotics are increasingly recognized as anthropogenic contaminants in soils, and they can persist through a complex vicious cycle of transformation and bioaccumulation. In this study, we quantified 11 quinolones (QNs), 5 sulfonamides (SAs), 5 macrolides (MLs), and 4 tetracyclines (TCs) in soils at three soil layers (0–10, 10–20, 20–40 cm) in a typical peri-urban catchment in the Yangtze River Delta, Eastern China. The results showed that total antibiotic levels were significantly higher in cropland topsoil (p < 0.05) compared to orchards and forests (p < 0.05). Moreover, a significant seasonal variation for antibiotic concentrations in croplands’ topsoil were observed in the summer (50.59 ± 84.55 ng/g) and winter (112.44 ± 140.58 ng/g). Chlortetracycline (15.30 ± 45.44 ng/g), enrofloxacin (0.43 ± 0.93 ng/g), sulfamethazine (0.05 ± 0.02 ng/g) and clarithromycin (0.03 ± 0.03 ng/g) were detected with the highest frequencies within TCs, QNs, SAs, and MLs, respectively. Concentrations of TCs, QNs, and SAs decreased with increasing soil depth. The concentrations of TCs, QNs, and SAs were significantly affected by the intensity of human activities. According to the results of redundancy analysis (RDA), anthropogenic effects on the distribution of antibiotics in soils in winter were so strong that they dwarfed the effects of environmental factors. In summer, human activities and their interactions with environmental factors were the dominant contributors to variations in soil antibiotics. In addition, the results of RDA suggested that soil pH and organic matter closely correlated with the levels of antibiotics, and Actinobacteria was the predominant contributor to the biodegradation of antibiotics in this study area.
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24595. 题目: Visible-light-driven photocatalytic degradation of ciprofloxacin by a ternary Mn₂O₃/Mn₃O₄/MnO₂ valence state heterojunction
文章编号: N18080202
期刊: Chemical Engineering Journal
作者: Jianhui Zhao, Zhiwei Zhao, Ning Li, Jun Nan, Ruixin Yu, Jinying Du
更新时间: 2018-08-02
摘要: Valence state heterostructure exhibits great potential for contaminants remediation from water and wastewater with effective charge separation and little energy loss. However, the preparation process commonly shows complex with uncontrolled manner, forming undesired valence states, which hinders the advancement of valence state heterostructure. Herein, an Oxone induced strategy is established to controllably design manganese-based valence state heterostructure for the first time. A superior Mn₂O₃/Mn₃O₄/MnO₂ (molar ratio of 3:1:2) photocatalyst with dual Ⅱ heterostructures was generated by Oxone (0.3 mM) induced Mn₂O₃ (0.2 g/L) under visible light. The Mn₂O₃/Mn₃O₄/MnO₂ heterojunction achieved 95.6% removal and 63.9% mineralization of ciprofloxacin (cipro) under visible light irradiation for 40 min. The excellent catalytic performance was derived from the improved surface area, decreased isoelectric point, enhanced light absorption and efficient charge separation of the Mn₂O₃/Mn₃O₄/MnO₂ heterostructure. Moreover, the radicals trapping experiment and Electron paramagnetic resonance (EPR) measurement revealed the dominant roles of holes and superoxide radicals for cipro degradation. Furthermore, the reusable Mn₂O₃/Mn₃O₄/MnO₂ could remove cipro selectively with co-existing natural organic matters and inorganic ions, which exhibited high practicability in real waters. Impressively, this work provides an innovative approach for controllable design of valence state heterostructure and fabricates a promising photocatalyst towards antibiotics degradation.
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24596. 题目: Influence of organic management on As bioavailability: Soil quality and tomato As uptake
文章编号: N18080201
期刊: Chemosphere
作者: Silvia Rita Stazi, Roberto Mancinelli, Rosita Marabottini, Enrica Allevato, Emanuele Radicetti, Enio Campiglia, Sara Marinari
更新时间: 2018-08-02
摘要: The research studied the effects of organic vs. conventional management of soil quality and tomato yield quality, cultivated in a geogenic arsenic contaminated soil. The chemical and biochemical properties were analyzed to evaluate soil quality, arsenic mobility and its phyto-availability, as well as arsenic accumulation in the tomato plant tissues and if tomatoes cultivated in arsenic rich soil represents a risk for human health. A general improvement of tomato growth and soil quality was observed in the organic management, where soil organic carbon increased from 1.24 to 1.48% and total nitrogen content. The arsenic content of the soil in the organic management increased from 57.0 to 65.3 mg kg⁻¹, probably due to a greater content of organic matter which permitted the soil to retain the arsenic naturally present in irrigation water. An increase of bioavailable arsenic was observed in the conventional management compared to the organic one (7.05 vs 6.18 mg kg⁻¹). The bioavailable form of metalloid may affect soil microbial community structure assessed using El-FAME analysis. The increase of the total arsenic concentration in the organic management did not represent a stress factor for soil microbial biomass carbon (Cmic), which was higher in the organic management than in the conventional one (267 vs. 132 μg Cmic g⁻¹). Even if the organic management caused an increase of total arsenic concentration in the soil due to the enhanced organic matter content, retaining arsenic from irrigation water, this management mitigates the arsenic uptake by tomato plants reducing the mobility of the metalloid.

24597. 题目: The interplay between natural organic matter and bromide on bromine substitution
文章编号: N18080110
期刊: Science of The Total Environment
作者: Mahmut S. Ersan, Chao Liu, Gary Amy, Tanju Karanfil
更新时间: 2018-08-01
摘要: This study examined the interplay between bromide and DOM characteristics, described with SUVA₂₅₄, in terms of formation and speciation of selected DBPs [trihalomethanes (THMs), haloacetic acids (HAAs), and haloacetonitriles (HANs)] during chlorination under various water treatment conditions. Cytotoxicity evaluations were also conducted based on the types and amounts of DBPs formed and their corresponding cytotoxicity index values. The results showed that the formation of THMs and HAAs increased as the specific UV absorbance at 254 nm (SUVA₂₅₄) of the waters increased; however, there was no clear trend for HANs. THM and HAN formation increased with increasing bromide levels, while there was no bromide effect on the HAA formation. Lower HAA5 (monochloroaceticacid, monobromoaceticacid, dichloroaceticacid, trichloroaceticacid, dibromoaceticacid) to HAA9 (monochloroaceticacid, monobromoaceticacid, dichloroaceticacid, trichloroaceticacid, dibromoaceticacid, bromochloroaceticacid, bromodichloroaceticacid, dibromochloroaceticacid, tribromoaceticacid) ratios, independent of SUVA₂₅₄, were observed with increasing bromide levels. Bromine substitution factor (BSF) values were in the order of BSF_DHAN > BSF_THAA > BSF_THM ≈ BSF_DHAA. BSF values for all class of DBPs decreased with increasing SUVA₂₅₄. TOX formation increased with increasing SUVA₂₅₄ without an impact of bromide concentration. UTOX/TOX ratios were higher in treated low SUVA₂₅₄ waters than raw waters having higher SUVA₂₅₄ values, and they decreased with increasing initial bromide concentration in all sources. Increasing bromide concentration from 0.5 μM to 10 μM elevated the calculated cytotoxicity index values of waters. Despite their much lower (approximately ~10 times) formation as compared to THMs and HAAs, HANs controlled the calculated cytotoxicity of studied waters.
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24598. 题目: The influence of aging on the comparative terrestrial ecotoxicity potential of copper and zinc in soils
文章编号: N18080109
期刊: Environmental Science and Pollution Research
作者: Aiju Liu, Qiang Liao, Mingzhu Li, Menghong Li, Zilin Meng, Qian Zhang, Huansheng Cao
更新时间: 2018-08-01
摘要: Metal exposure to terrestrial organism is influenced by the reactivity of the solid-phase metal pool. Aging is one of the important factors that control the reactivity of the solid-phase metal pool in soil. In this study, the selected 13 soils were collected from different locations of China, representing different soil types. The reactivity variation of spiked Cu and Zn with aging was assessed in these 13 soils, and their comparative toxicity potentials (CTPs) were also calculated. The median reactive fractions (f_reactive) of Cu and Zn with 95% confidence intervals were 1.6 × 10⁻² (3.5 × 10⁻⁶ to 2.2 × 10⁻¹) and 0.10 (9.1 × 10⁻⁴ to 0.44) kg_reactive/kg_total, and the median CTPs for Cu and Zn were 2.09 (8.1 × 10⁻⁴ to 2.2 × 10⁴) and 0.85 (8.5 × 10⁻⁴ to 7.2 × 10²) m³/kg day, respectively. The statistical analysis indicated that aging variability in the CTP of Cu and Zn was mainly associated with the variability in soil organic carbon and pH. These results stress the importance of dealing with aging in the calculation of CTPs for terrestrial ecotoxicity of metals.

24599. 题目: Vertical and seasonal variations of soil carbon pools in ginkgo agroforestry systems in eastern China
文章编号: N18080108
期刊: CATENA
作者: Jing Guo, Bo Wang, Guibin Wang, Yaqiong Wu, Fuliang Cao
更新时间: 2018-08-01
摘要: Agroforestry provides opportunities to decrease the levels of carbon dioxide (CO₂) released into the atmosphere by increasing the carbon (C) stored in agricultural systems. In agroforestry systems, soil C pools serve as the most important and stable C sink, but there is limited information on the vertical and seasonal variations of soil C pools. In this study, the vertical and seasonal variations of soil organic C (SOC) and its labile pools were measured in five planting systems: a pure ginkgo (Gingko biloba. L) planting system, a pure wheat (Triticum aestivum L.) field, a pure metasequoia (Metasequoia glyptostroboides Hu et Cheng) seedling system, a ginkgo and wheat agroforestry system, and a ginkgo and metasequoia seedling agroforestry system. Among these systems, the ginkgo and wheat system had a significantly higher SOC content than the other systems throughout the year, particularly at depths of 0–10 cm and 10–20 cm. Additionally, the pure ginkgo and pure metasequoia systems had lower SOC contents than the other planting systems, and this decrease was attributed to the relatively limited tree litter input and lower fine root biomass. Microbial biomass C (MBC) and soil readily oxidizable C (ROC) exhibited similar vertical and seasonal variations and reached minimum values in winter. The highest MBC and ROC contents were observed in the ginkgo and wheat system at a depth of 0–10 cm, i.e., 127.3 mg kg⁻¹ and 4.49 g kg⁻¹, respectively. The highest water-soluble organic carbon (WSOC) content was observed in summer at a depth of 0–10 cm, i.e., 472.2 mg kg⁻¹. A Pearson correlation analysis indicated that soil properties were significantly correlated with SOC and labile C fractions. The results suggested that an agroforestry system resulted in a greater increase in the soil C sink; in particular, the ginkgo and wheat system achieved the best results. Basic soil properties played key roles in soil carbon formation. These results provide important information about SOC and labile C fraction dynamics resulting from planting systems and depth variations and strengthen our understanding of soil C sequestration in agroforestry systems.

24600. 题目: Effects of mixed surfactants on the bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) in crops and the bioremediation of contaminated farmlands
文章编号: N18080107
期刊: Science of The Total Environment
作者: Zhiheng Li, Wei Wang, Lizhong Zhu
更新时间: 2018-08-01
摘要: Given the widespread contamination of polycyclic aromatic hydrocarbons (PAHs) in farmland, it is necessary to develop a technology to ensure the safety of agricultural productions and remediate the contaminated soils. In this study, a series of mixed surfactants were utilized to reduce the uptake of PAHs by crops in farming period and enhance the plant-microbe associated biodegradation in fallow period. During the farming period, the mixtures of cetyltrimethyl ammonium bromide (CTMAB) and Tween 80 were attached on soil by cationic-exchange and hydrogen bond, respectively, which increased soil organic matter to partition the bio-available fraction of PAHs. The maximum reduction of phenanthrene and pyrene was 88.6% and 94.9% for chrysanthemum (Chrysanthemum coronarium L.), and 90.6% and 91.9% for raphanus (Raphanus sativus L.), respectively. During the fallow period, sodium dodecyl benzene sulfonate (SDBS) reduced the adsorption loss of Tween 80 on soil to enhance desorption of PAHs. The mixtures of SDBS and Tween 80 increased the water-soluble fraction of PAHs in soils, modified bacterial community structure, and enriched the functional genes involved cell motility and signal transduction. Removal efficiencies of phenanthrene and pyrene in soils were high to 86.7% and 90.7%. This systematic technology provided an effective solution to remediate and plant on PAH-contaminated farmlands.
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