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23321. 题目: Interactive effects of pH and aluminum on the secretion of organic acid anions by roots and related metabolic factors in Citrus sinensis roots and leaves
文章编号: N20030901
期刊: Environmental Pollution
作者: Tao-Yu Yang, Yi-Ping Qi, Hui-Yu Huang, Feng-Lin Wu, Wei-Tao Huang, Chong-Ling Deng, Lin-Tong Yang, Li-Song Chen
更新时间: 2020-03-09
摘要: Low pH and aluminum (Al)-toxicity often coexist in acidic soils. Citrus sinensis seedlings were treated with nutrient solution at a pH of 2.5, 3.0, 3.5 or 4.0 and an Al concentration of 0 or 1 mM for 18 weeks. Thereafter, malate, citrate, isocitrate, acid-metabolizing enzymes, and nonstructural carbohydrates in roots and leaves, and release of malate and citrate from roots were measured. Al concentration in roots and leaves increased under Al-toxicity, but it declined with elevating nutrient solution pH. Al-toxicity increased the levels of glucose, fructose, sucrose and total soluble sugars in leaves and roots at each given pH except for a similar sucrose level at pH 2.5–3.0, but it reduced or did not alter the levels of starch and total nonstructural carbohydrates (TNC) in leaves and roots with the exception that Al improved TNC level in roots at pH 4.0. Levels of nonstructural carbohydrates in roots and leaves rose with reducing pH with a few exceptions with or without Al-toxicity. A potential model for the possible role of root organic acid (OA) metabolism (anions) in C. sinensis Al-tolerance was proposed. With Al-toxicity, the elevated pH upregulated the OA metabolism, and increased the flow of carbon to OA metabolism, and the accumulation of malate and citrate in roots and subsequent release of them, thus reducing root and leaf Al and hence eliminating Al-toxicity. Without Al-toxicity, low pH stimulated the exudation of malate and citrate, an adaptive response of Citrus to low pH. The interactive effects of pH and pH on OA metabolism were different between roots and leaves.

23322. 题目: Fabrication of L-cysteine stabilized α-FeOOH nanocomposite on porous hydrophilic biochar as an effective adsorbent for Pb2+ removal
文章编号: N20030814
期刊: Science of The Total Environment
作者: Shuaishuai Zhang, Qing Du, Yuqing Sun, Jingpeng Song, Fan Yang, Daniel C.W. Tsang
更新时间: 2020-03-08
摘要: Lead (Pb) pollution has caused worldwide attention as it can cause hazards to humans and the environment. Chemical properties and structures of the adsorbent greatly influence the Pb2+ removal efficiency. L-cysteine (L-cy) stabilized porous hydrophilic biochar-supported α-FeOOH nanocomposites (L-cy/) are prepared as an efficient adsorbent via a cheap and simple one-step hydrothermal method for removing Pb2+ from aqueous solution. Characterizations of the synthesized L-cy/ revealed that the iron particles distributed uniformly on the surface of porous hydrophilic biochar. The equilibrium adsorption capacity of the L-cy/ reaches up to 103.04 mg g−1for Pb2+ removal, higher than other typical materials reported preiously. The adsorption kinetics and isotherms were fitted well with the pseudo-second-order model and the Freundlich model, respectively, suggesting chemical adsorption on the heterogeneous surface and pores of L-cy/ The introduction of L-cysteine provides abundant surface N- and S-containing functional groups as active sites for Pb2+ adsorption and also plays an important role in altering the porous structure, distribution of α-FeOOH nanoparticles, affinity of iron species to biochar, and surface functional groups, which determined the performance of the resultant composites. Notably, regeneration experiments show that Pb2+ adsorption capacity still maintains at 77.3 mg g−1 on L-cy/ after five successive utilizations, indicating the potential applicability for removing Pb2+ from aqueous solution.

23323. 题目: Double effects of biochar in affecting the macropore system of paddy soils identified by high-resolution X-ray tomography
文章编号: N20030813
期刊: Science of The Total Environment
作者: Xiuling Yu, Shenggao Lu
更新时间: 2020-03-08
摘要: Biochars are widely used to improve soil macropore structures. However, the size-dependent effects of biochars in affecting macropore structure still remain unclear. In this study, the modification of soil macropore structure following biochar addition was investigated by high-resolution X-ray tomography (CT) and advanced data analytical methods. Quantification of soil macropore structure (>52 μm) was based on the intact soil cores (5 cm in diameter and 7 cm in height) collected from biochar-amended paddy soil. The treatments were: (a) control (CK), (b) rice straw biochar (RSB), (c) corn straw biochar (CSB), and (d) bamboo biochar (BB). The application rate of biochar was 25 Mg ha−1 (w/w). Results revealed that the biochars affected the soil macropores through both occupying effect and expansion effect. The occupying effect means that the biochar particles occupy the original pore space of the soil and reduce the soil porosity, while the expansion effect means that the biochar particles produce additional pore space in the soil matrix and increase the soil porosity. For all the biochar treatments in our study, the occupying effect was dominated. Therefore, the connected- and isolated porosity of biochar-treated soils were significantly lower than those of CK. The size-dependent effects of biochar in modifying soil macropores were observed. For RSB treatment, the expansion effect predominated at the size of <1200 μm and >1800 μm, while both the occupying effect and expansion effect were observed at the size of 1200–1800 μm. For CSB and BB treatments, the expansion effect predominate only at the size of 600–1200 μm; whereas both the occupying effect and expansion effect were observed at the size of <600 μm and >1800 μm. Our results indicated that the effects of biochar on soil macroporosity were dependent on the combined effects the occupying effect and expansion effect. In conclusion, all the biochar types in this study have adverse effects in increasing the soil macroporosity.

23324. 题目: Feasibility study on a new pomelo peel derived biochar for tetracycline antibiotics removal in swine wastewater
文章编号: N20030812
期刊: Science of The Total Environment
作者: Dongle Cheng, Huu Hao Ngo, Wenshan Guo, Soon Woong Chang, Dinh Duc Nguyen, Xinbo Zhang, Sunita Varjani, Yi Liu
更新时间: 2020-03-08
摘要: Removal of tetracycline antibiotics (TCs) by biochar adsorption is emerging as a cost-effective and environmentally friendly strategy. This study developed a novel pomelo peel derived biochar, which was prepared at 400 °C (BC-400) and 600 °C (BC-600) under nitrogen conditions. To enhance the adsorption capacity, BC-400 was further activated by KOH at 600 °C with a KOH: BC-400 ratio of 4:1. The activated biochar (BC-KOH) displayed a much larger surface area (2457.37 m2/g) and total pore volume (1.14 cm3/g) than BC-400 and BC-600. High adsorption capacity of BC-KOH was achieved for removing tetracycline (476.19 mg/g), oxytetracycline (407.5 mg/g) and chlortetracycline (555.56 mg/g) simultaneously at 313.15 K, which was comparable with other biochars derived from agricultural wastes reported previously. The adsorption data could be fitted by the pseudo-second-order kinetic model and Langmuir isotherm model successfully. The initial solution pH indicated the potential influence of TCs adsorption capacity on BC-KOH. These results suggest that pore filling, electrostatic interaction and π–π interactions between the adsorbent and adsorbate may constitute the main adsorption mechanism. BC-KOH can be used as a potential adsorbent for removing TCs from swine wastewater effectively, cheaply and in an environmentally friendly way.

23325. 题目: Generation of hydroxyl radical during chlorination of hydroxyphenols and natural organic matter extracts
文章编号: N20030811
期刊: Water Research
作者: Eva M. Rodriguez, Urs von Gunten
更新时间: 2020-03-08
摘要: The generation of hydroxyl radicals (·OH) during the chlorination of air saturated solutions of different hydroxyphenols (hydroquinone, resorcinol, catechol, gallic and tannic acids) at pH 7 has been determined by the formation of phenol (in presence of benzene in excess) or 2-hydroxyterephthalic acid (in presence of terephthalic acid). Formation of ·OH was only detected during the chlorination of o- or p-hydroxyphenols, compounds that react with chlorine by electron transfer forming the corresponding semiquinones/quinones. In aerated solutions, oxygen is reduced by the semiquinone to the superoxide radical, O2·-, which reacts with HOCl to ·OH. Compared to the studied o-hydroxyphenols, the lower reactivity of hydroquinone towards chlorine favours the development of the reaction between chlorine and O2·-, and its ·OH formation potential is ∼50 times higher. The extent of ·OH generated increased with the concentration of the hydroxyphenol and chlorine, but the ·OH yield (moles formed per mole of hydroxyphenol eliminated), decreased due to the formation of the quinone, that acts as O2·- scavenger. The yield was almost not affected by the pH (6 ≤ pH ≤ 7.5), whereas a strong impact of dissolved O2 was observed. The ·OH production was null in absence of O2 and 2.5–3 times higher at oxygen saturated conditions compared to air-saturated. Contrary to chlorination, during bromination of hydroquinone ·OH was not formed, which can be attributable to a much faster consumption of the oxidant, with no chance for O2·- to react with bromine. Formation of ·OH during the chlorination of different NOM extracts (SRHA, SRFA, PLFA and Nordic Lake NOM) and water from Lake Greifensee (Switzerland) was also studied using terephthalic acid as ·OH scavenger. For SRHA, SRFA and Nordic Lake NOM (all of allochthonous origin and presenting high electron-donating capacity, EDC), ·OH yields expressed as moles formed per mole of DOC0 (%), were between 1.1 and 2.0, similar to that of hydroquinone (∼1.5). For PLFA and Lake Greifensee water (autochthonous, lower EDC) much lower ·OH yields were observed (0.1–0.3). Both chlorination rate and EDC, the later favouring the formation/stabilization of O2·-, seem to be key factors involved in ·OH generation during the chlorination of NOM. A mechanism for these findings could be proposed based on kinetic simulations of hydroquinone chlorination at pH 7.

23326. 题目: Modeling trace metal partitioning and speciation at the sediment-water interface using a chemical equilibrium model
文章编号: N20030810
期刊: Marine Chemistry
作者: Li Li, Cuiqin Zhang, Yijun Ren, Franco Pala, Xiaojing Wang, Xiaotong Zhen, Jihua Liu, Xuefa Shi
更新时间: 2020-03-08
摘要: Isotherm adsorption experiments for Pb, Cd and Zn were carried out with coastal sediments from China under oxic sediment-water conditions. The conditional equilibrium constants (Kads) determined from the adsorption isotherms were found to be most strongly correlated with Mn oxides (MnOx) for Pb and Cd, and with particulate organic carbon (POC) for Zn. MnOx and POC were then used as the surrogate metal-binding phases in a sediment-water chemical equilibrium model (SCEM). The apparent equilibrium constants (βsed, Me⁎) of the SCEM were determined to be 109.56±0.41 for Pb (n = 9), 105.25±0.34 for Zn (n = 7), and 106.51±0.29 for Cd (n = 7). The SCEM was then used to predict the free metal ion activities ({Me2+}) in seawaters of Jinzhou Bay, China. The SCEM-predicted {Me2+} compared well with the measured ones for Pb and Zn in seawater. However, the predicted {Cd2+} was higher than measured, which may reflect a detoxification mechanism of marine organisms in Jinzhou Bay seawater. Overall, a model of this kind can be highly useful for predicting {Men+} in the overlying waters based on the surface sediment chemistry, and can contribute to the development of sediment quality guidelines by linking them with the corresponding water quality criteria.

23327. 题目: Neoformed aluminosilicate and phytogenic silica are competitive sinks in the silicon soil–plant cycle
文章编号: N20030809
期刊: Geoderma
作者: Zimin Li, Jean-Thomas Cornelis, Charles Vander Linden, Eric Van Ranst, Bruno Delvaux
更新时间: 2020-03-08
摘要: In soils, mineral weathering and phytolith dissolution release aqueous monosilicic acid that can be taken up by plant, adsorbed on mineral surfaces, entrapped in neoformed clay minerals, or exported to watersheds. The balance between biotic and abiotic processes determines the fluxes of bioavailable silicon (Si), impacting plant growth and health, and diatoms biomass, hence the oceanic capacity to fix carbon dioxide. Here we quantified this balance in an experimental system using rice and an albic soil material (quartz grains) containing no weatherable silicate minerals. Materials representing a soil weathering gradient were prepared by adding variable amounts of silicate minerals within fresh powdered tephrite (<83 µm) as a source of weatherable minerals whereas phytogenic Si was supplied within phytolith-rich biochar. We quantified the distribution of Si in leachate, soil and plant reservoirs. Weatherable minerals rapidly released Si that flowed into two main sinks: allophanic substances neoformed in soil from released Si and aluminum (Al), and phytoliths formed by precipitation of absorbed silica in plant tissues. The leaching of Si was negligible. Allophane rapidly formed at a maximum rate of 0.85 g allophane kg−1 soil day−1. Of the Si stock of weatherable minerals, 7–14% contributed to allophanic Si and less than 1% to phytogenic Si. The contribution of supplied phytoliths to plant Si accumulation markedly increased from 26 to 80% with the decrease in weatherable mineral reserve from 405 to 5 cmolc kg−1. Weatherable minerals primarily controlled bioavailable Si while phytoliths increasingly contributed to Si plant uptake with increasing mineral depletion. Returning phytoliths to soil thus boosts the biological recycling of Si in proportion to the increase in soil weathering stage.

23328. 题目: Soil loss tolerance in calcareous soils of a semi‐arid region: its evaluation, prediction, and influential parameters
文章编号: N20030808
期刊: Land Degradation & Development
作者: Yaser Ostovari, Ali Akbar Moosavi, Hamid Reza Pourghasemi
更新时间: 2020-03-08
摘要: Predicting soil loss tolerance (T‐value) as a first and crucial step in assessing soil erosion using pedotransfer functions (PTFs) could save time and cost. Therefore, this study aimed to evaluate T‐value and its influential parameters in calcareous soils of the Dorudzan Watershed, Fars Province, Iran and to develop PTFs for its prediction using easily measureable soil properties. T‐value was determined in 60 soil profiles based on the soil thickness method. Various basic soil properties were used to develop five PTFs using stepwise multiple linear regression. T‐value varied from 3.5 to 22.5 with a mean value of 10.4 t ha−1 y−1, which is approximately equal to the proposed value by USDA (11 t ha−1 y−1). T‐value in Inceptisols located in the dam shore and agricultural lands was significantly higher than that of Entisols located in the forest and rangelands. Organic matter (OM) with a correlation coefficient of 0.77 with T‐value was the most influential variable in prediction of T‐value. The PTF 5, which used OM, soil aggregate stability, and permeability, with the highest R2 (0.72 and 0.79), the lowest ME (−0.44 and 1.75 t ha−1 y−1), the lowest RMSE (2.98 and 2.75 t ha−1 y−1) and the minimum AIC (51.1 and 17.2) provided the best predictions for T‐value. However, when considering the acceptable indices and easier measureable soil properties (OM, soil erodibility, and pH) in PTF 3, we concluded that it was the best model to predict T‐value. Generally, the application of thickness method is recommended to determine T‐value in semi‐arid regions.

23329. 题目: Loss-On-Ignition Estimates for Soil Organic Carbon in Great Lakes Freshwater Coastal Wetlands
文章编号: N20030807
期刊: Wetlands
作者: Katherine N. Braun, Ethan J. Theuerkauf, Matthew T. Hurtgen, Andrew L. Masterson, Daniel E. Horton
更新时间: 2020-03-08
摘要: Soil organic carbon (SOC) is an important component of freshwater wetlands that may be used to quantify ecosystem services and prioritize conservation efforts. Measuring SOC directly via elemental analysis is often time and cost-prohibitive. Loss-on-ignition (LOI) is a rapid and low-cost method for determining soil organic matter; however, LOI data must be converted to SOC data using a soil type-specific regression model and no models currently exist for freshwater coastal wetlands. To address this gap, we performed regression analyses that convert percent organic matter measured from LOI to SOC for freshwater coastal wetlands in the southern basin of Lake Michigan. Analyses across 6 Lake Michigan wetlands provide a regression model capable of estimating SOC within ±3.5% uncertainty (r2 = 0.757), a threshold useful for wetland management and large-scale soil surveys. Future research should explore the LOI-SOC relationship at other freshwater coastal wetlands – to investigate whether the correlation values found here are typical of these systems and to refine our regression model using data from disparate freshwater locales.

23330. 题目: Combined effects of nitrogen fertilizer and biochar on greenhouse gas emissions and net ecosystem economic budget from a coastal saline rice field in southeastern China
文章编号: N20030806
期刊: Environmental Science and Pollution Research
作者: Liying Sun, Junyin Deng, Changhua Fan, Jia Li, Yinglie Liu
更新时间: 2020-03-08
摘要: Biochar amendment has complex impacts on greenhouse gas emissions, crop production and economic benefit. However, few studies have comprehensively investigated the effects of biochar amendment in coastal saline rice fields. Thus, a biochar amendment field experiment was established in a coastal saline rice field in China to estimate the CH4 and N2O emissions, global warming potential (GWP), greenhouse gas intensity (GHGI), and net ecosystem economic budget (NEEB) of the biochar amendment during the rice growing season in 2017. There were six treatments (N0B0, N0B1, N0B2, N1B0, N1B1, N1B2) with different N fertilizer levels of 0 and 300 kg N ha−1 and biochar rates of 0, 20, and 40 t ha−1. The results showed that the application of N fertilizer increased N2O emissions and rice yield by 128.3% (p < 0.001) and 44.4% (p < 0.001), respectively, while decreased the GHGI by 20.5% (p < 0.01); additionally, there were no significant effects on the CH4 emissions and GWP compared with the treatments without N fertilizer. Although biochar amendment significantly increased the N2O emissions and rice yield by 13.7–38.1% and 31.5–34.9%, respectively, biochar amendment had no significant effects on CH4 emissions, GWP, and GHGI relative to the treatments without biochar amendment. From an economic perspective, N fertilizer significantly increased the NEEB by 135.5%, relative to the treatments without N fertilizer. Due to the high price of biochar and the large quantity applied, biochar amendment significantly reduced the NEEB by 99.8–229.3% compared with the treatments without biochar amendment. Considering the different characters between field-aged biochar and fresh biochar. Thus, long-term observations are needed to evaluate the environmental and economic profits affected by biochar and N fertilizer.

23331. 题目: Bone Char Mediated Dechlorination of Trichloroethylene by Green Rust
文章编号: N20030805
期刊: Environmental Science & Technology
作者: Jing Ai, Hui Ma, Dominique J. Tobler, Marco C. Mangayayam, Changyong Lu, Frans W. J. van den Berg, Weizhao Yin, Hans Christian Bruun Hansen
更新时间: 2020-03-08
摘要: Biochars function as electron transfer mediators and thus catalyze redox transformations of environmental pollutants. A previous study has shown that bone char (BC) has high catalytic activity for reduction of chlorinated ethylenes using layered Fe(II)–Fe(III) hydroxide (green rust) as reductant. In the present study, we studied the rate of trichloroethylene (TCE) reduction by green rust in the presence of BCs obtained at pyrolysis temperatures (PTs) from 450 to 1050 °C. The reactivity increased with PT, yielding a maximum pseudo-first-order rate constant (k) of 2.0 h–1 in the presence of BC pyrolyzed at 950 °C, while no reaction was seen for BC pyrolyzed at 450 °C. TCE sorption, specific surface area, extent of graphitization, carbon content, and aromaticity of the BCs also increased with PT. The electron-accepting capacity (EAC) of BC peaked at PT of 850 °C, and EAC was linearly correlated with the sum of concentrations of quinoid, quaternary N, and pyridine-N-oxide groups measured by XPS. Moreover, no TCE reduction was seen with graphene nanoparticles and graphitized carbon black, which have high degrees of graphitization but low EAC values. Further analyses showed that TCE reduction rates are well correlated with the EAC and the C/H ratio (proxy of electrical conductivity) of the BCs, strongly indicating that both electron-accepting functional groups and electron-conducting domains are crucial for the BC catalytic reactivity. The present study delineates conditions for designing redox-reactive biochars to be used for remediation of sites contaminated with chlorinated solvents.

23332. 题目: Ultraviolet photolysis of metformin: mechanisms of environmental factors, identification of intermediates, and density functional theory calculations
文章编号: N20030804
期刊: Environmental Science and Pollution Research
作者: Wenting Lin, Xiaohan Zhang, Ping Li, Yongzhen Tan, Yuan Ren
更新时间: 2020-03-08
摘要: As a commonly used anti-diabetic drug, metformin (MEF) is frequently detected in different water bodies which pose a potential threat to human health and the ecological environment. In this study, oxidative degradation of MEF under ultraviolet (UV) light was studied, and its influencing factors, photolysis mechanism, and intermediates identification carried out as well. The results showed that the hydroxyl radical contributed 73% during the 6 h MEF photolysis process among the reactive oxygen species (ROS). In addition, triplet excited-state organic matter and singlet oxygen also played a role in the photolysis process. The reaction rates of hydroxyl radical and singlet oxygen with MEF are (6.45 ± 0.4) × 109 and (5.4 ± 0.7) × 106 L·(mol s)−1, respectively. By calculating the light screening effect of environmental factors, it is found that the presence of NO3− and Cl− had a greater excitation effect on ROS than the screening effect, and generally promoted the photolysis rates of MEF from 90.3 to 193.5% and from 16.1 to 80.6% during the 6-h reaction process, respectively. For bicarbonate and fulvic acid, the light screening effects were dominant and inhibited photolysis rates by 10–52% and 13–71%, respectively. The results demonstrated that the photoreactivity of environmental factors in water is the cause of the different photodegradation rates of MEF. The oxidative degradation product of MEF under UV light was detected by UPLC/Q-TOF as methylbiguanide (MBG), 2,4-diamino-1,3,5-triazine (2,4-DAT), biguanide (BGN), 1,1-dimethylguanidine (1,1-DiMBG), 4-amino-2-imino-1-methyl-1,2-dihydro-1, 3,5-triazine (4,2,1-AIMT), and 2-amino-4-methylamino-1,3,5-triazine (2,4-AMT). The result which showed that the primary sites of ∙OH attacked is consistent with that of density functional theory calculation.

23333. 题目: Distribution and removal of fluorescent dissolved organic matter in 15 municipal wastewater treatment plants in China
文章编号: N20030803
期刊: Chemosphere
作者: Juechun Li, Liye Wang, Jinju Geng, Shengnan Li, Qingmiao Yu, Ke Xu, Hongqiang Ren
更新时间: 2020-03-08
摘要: Fluorescent dissolved organic matter (FDOM), having complex structures like aromatic structure and double bond structure, is able to represent relatively refractory parts of dissolved organic matter (DOM). This study investigated the distribution of FDOM in the influents and the removal in the secondary effluents of 15 municipal wastewater treatment plants (WWTPs) in 15 provincial capitals of China. Eight components have been identified using excitation emission matrix combined with parallel factor analysis (EEM-PARAFAC). Tryptophan-like (C1 or C4), terrestrial humic-like (C2) and microbial humic-like (C3) fluorescent components were major FDOM components in municipal wastewater, appearing in 11 WWTPs simultaneously. The removal of total fluorescence was generally about 30%–40%, while hydrophobic humic-like compounds (C5 and C8) were the most refractory components with 4%–16% removal and C3 was the second most refractory with −11%–41% removal. The compositions of FDOM in municipal wastewater were different in northeast/west and middle/east regions according to the self-organized map (SOM) analysis. Wastewater sources had more important influence on fluorescent characteristics of secondary effluents than biological treatment processes. Besides, this study found that humification index (HIX) was the most suitable index to describe the bulk fluorescent character of wastewater since it had a good correlation with abundance, removal and ratios of main fluorescent components either in the influents or in the secondary effluents.

23334. 题目: Light-absorbing and fluorescent properties of atmospheric brown carbon: A case study in Nanjing, China
文章编号: N20030802
期刊: Chemosphere
作者: Xinchun Xie, Yanfang Chen, Dongyang Nie, Yue Liu, Yue Liu, Ruoyuan Lei, Xiuyong Zhao, Haiwei Li, Xinlei Ge
更新时间: 2020-03-08
摘要: Brown carbon (BrC), a significant wavelength-dependent atmospheric absorber of solar radiation, plays a key role in photochemistry and long-lasting haze episodes. Herein, two types of BrC extracted from one-year PM2.5 samples (June 2017–May 2018 in Nanjing), i.e. methanol-extracted organic carbon (MSOC) and ultrapure water-extracted organic carbon (WSOC), were obtained to investigate distinct optical properties of atmospheric BrC. The extraction efficiency of BrC was as high as 91% in methanol solution, and the corresponding light absorption coefficient (Abs) of MSOC at 365 nm (Abs365-MSOC, 7.75 ± 3.95 Mm−1) was approximately 1.6 times that of WSOC (Abs365-WSOC, 4.84 ± 2.97 Mm−1), indicating that the water-insoluble compounds mostly affected the light absorption of BrC. The seasonal variations of Abs365-WSOC and Abs365-MSOC were followed the sequence of winter > spring > autumn > summer, due to the dominated emissions from fossil fuel combustion and biomass burning in the cooling seasons. Additionally, four fluorescent chromophores in WSOC and MSOC, containing three humic-like chromophores and one protein-like chromophore, exhibited the highest fluorescent intensities in winter but weakest in summer. The lower humification index (HIX) in MSOC reflects that humic-like chromophores were preferentially water-soluble, in coordination with high degree of photo-oxidation and aromaticity. Fluorescence index (FI) of BrC was also higher in winter because of the effects of photo-bleaching, whereas biological index (BIX) remained stable throughout a year. Considering the correlation between primary organic carbon (POC) and secondary organic carbon (SOC), aside from the contribution of primary emissions, secondary formation has become another major source to atmospheric BrC in Nanjing.

23335. 题目: Sorption of ionized dyes on high-salinity microalgal residue derived biochar: Electron acceptor-donor and metal-organic bridging mechanisms
文章编号: N20030801
期刊: Journal of Hazardous Materials
作者: Xuefei Tan, Shishu Zhu, Pau Loke Show, Haiqun Qi, Shih-Hsin Ho
更新时间: 2020-03-08
摘要: Biochar (BC) has attracted much attention owing to its superior sorption capacity towards ionized organic contaminants. However, the mechanism of ionized organics sorption occurring within BC containing large amounts of minerals is still controversial. In this study, we demonstrate the physicochemical structure of high-salinity microalgal residue derived biochar (HSBC) and elucidate the corresponding sorption mechanisms for four ionized dyes along with determining the crucial role of involved minerals. The results indicate that sodium and calcium minerals mainly exist within HSBCs, and the pyrolysis temperature can dramatically regulate the phases and interfacial property of both carbon matrix and minerals. As a result, the HSBC shows a higher sorption potential, benefiting from abundant functional groups and high content of inorganic minerals. Using theoretical calculations, the activities of electron donor-acceptor interaction between HSBCs and different dyes are clearly illustrated, thereby identifying the critical role of Ca2+ in enhancing the removal of ionized dyes in HSBCs. In addition, Ca-containing minerals facilitate the sorption of ionized dyes in HSBCs by forming ternary complexes through metal-bridging mechanism. These results of mineral-induced dye sorption mechanisms help to better understand the sorption of ionized organics in high-salt containing BC and provide a new disposal strategy for hazardous microalgal residue, as well as provide a breakthrough in making the remediation of ionized organic contaminated microalgal residue derived absorbent feasible.

23336. 题目: Synergistic toxic effects of ball-milled biochar and copper oxide nanoparticles on Streptomyces coelicolor M145
文章编号: N20030715
期刊: Science of The Total Environment
作者: Xiaomei Liu, Jingchun Tang, Lan Wang, Rutao Liu
更新时间: 2020-03-07
摘要: The toxic effects of multi-nanomaterial systems are receiving increasing attention owing to their inevitable release of various nanomaterials. Knowledge of the bioavailability of the new carbon material ball-milled biochar (BMB) and its synergistic toxicity with metal oxide nanoparticles in bacteria is currently limited. In this study, the interactions of BMB with copper oxide nanoparticles (CuO NPs) and their synergistic toxicity towards Streptomyces coelicolor M145 were analyzed. Results showed that the cytotoxicity, ROS level and permeability of cells changed greatly with the pyrolysis temperatures of biochar and the concentrations of CuO NPs. The greatest cytotoxicity (up to 63.1%) was achieved by adding 20 mg/L CuO NPs to BMB700. The ROS level and cell permeability of this treatment was also the highest, about 4.2 folds and 2.9 folds greater than that of control, respectively. The combination of 10 mg/L BMB700 with 10 mg/L CuO NPs can maximize production of antibiotics, with the yield of undecylprodigiosin (RED) and actinorhodin (ACT) 3.0 times and 4.2 times higher than that in the control, respectively, and the change trend of related genes was consistent with that of antibiotics production. Mechanism analysis showed that the different adsorption capacity of BMB of different pyrolysis temperatures on copper ions played a vital role in the synergistic toxicity, and the increase in cell membrane permeability caused by cell collisions with particles was also an important reason for cytotoxicity. Overall, the synergistic toxicity of BMB with other NPs varies the pyrolysis temperatures, when considering the synergistic toxicity of these materials, the preparation conditions need to be taken into account so as to assess their environmental risks more accurately. On the other hand, this research may provide a new approach for the antibiotic industry to increase its output.

23337. 题目: Sorption behavior of real microplastics (MPs): Insights for organic micropollutants adsorption on a large set of well-characterized MPs
文章编号: N20030714
期刊: Science of The Total Environment
作者: Mohamed Ateia, Ting Zheng, Stefania Calace, Nishanth Tharayil, Srikanth Pilla, Tanju Karanfil
更新时间: 2020-03-07
摘要: Microplastics (MPs) have been recognized as transport vectors for micropollutants in the natural water environment and the food web; therefore, the sorption behavior of contaminant on MPs has recently gained an increased attention. However, a consensus has not yet been reached and information about the adsorption of water contaminants on real MPs remains elusive. Herein, we raise the question of Should we continue using pure polymers as surrogates for real MPs This first systematic study compared the adsorption of multiple micropollutants (i.e. a pesticide, a pharmaceutical, and perfluoroalkyl substances (PFAS)) on a large set of MPs (i.e. 20 well-characterized MPs) and kaolin. Material characterizations results showed various physicochemical and compositional differences between real and pure MPs. Pure polymers had lower normalized uptake values than real MPs in most cases. This was attributed to the surface roughness and/or the presence of fillers (e.g. talc and glass fiber) in real samples. Further, preloaded MPs with natural organic matter (NOM) showed an increased uptake of micropollutants due to forming a complex with NOM and/or co-sorption. These findings indicate that employing real MPs in research studies is critical for obtaining environmentally meaningful results, and the evaluation of MPs sorption behavior without NOM preloading can result in a significant underestimation for their actual values. We also provided an outlook the key areas for further investigations.

23338. 题目: Do wildfire and slope aspect affect soil water repellency in eucalypt plantations? – A two-year high resolution temporal dataset
文章编号: N20030713
期刊: CATENA
作者: Martinho A.S. Martins, Frank G.A. Verheijen, Maruxa C. Malvar, Dalila Serpa, Oscar González-Pelayo, Jan J. Keizer
更新时间: 2020-03-07
摘要: Wildfire can induce, enhance, or destroy natural soil water repellency (SWR) depending mostly on soil burnt severity, soil and vegetation types, soil organic matter (SOM) content and type, soil texture, peak soil temperature and remaining time and, antecedent soil moisture content (SMC). In Portugal, SWR in eucalypt stands has been shown to increase surface runoff under dry antecedent SMCs in both burnt and unburnt sites, thereby enhancing soil erosion. Despite the many hydrological implications of SWR, intensive field monitoring under a wide range of SMCs is still limited. This study aimed to improve our understanding of the role of slope aspect and wildfire on the temporal evolution of SWR in Mediterranean environments, which will be helpful for hydrological modelling and post-fire soil erosion risk assessment. In this sense, two burnt eucalypt plantations (wildfire of July 2010) were selected along a neighbouring, long-unburnt eucalypt stand, in north-central Portugal, in order to assess SWR and SMC's in a high temporal resolution. During the first two post-fire years, at 1–2 week intervals, surface (2.5 cm depth) SWR and SMC were monitored using the molarity of an ethanol droplet (MED) test and a soil probe, respectively. The results showed that the observed annual SWR was very high to extreme (80% of measurements ≥ 6 ethanol class) for all three sites. Wildfire reduced the annual median SWR by one class (extreme to very high) for both post-fire years. During prolonged dry periods the unburnt site was significantly more repellent (P < 0.01) and less spatially variable (P < 0.01) than the recently burnt site, while in the wet periods there was no significant difference. After burning, slope aspect did not have a strong impact on the annual median SWR class. However, the north-west aspect site recorded significantly (p < 0.01) greater annual frequencies of extreme repellency than the south-east aspect site (70–73% vs. 51–55%).

23339. 题目: Prediction of tropical volcanic soil organic carbon stocks by visible-near- and mid-infrared spectroscopy
文章编号: N20030712
期刊: CATENA
作者: Myriam Allo, Pierre Todoroff, Magali Jameux, Mathilde Stern, Louis Paulin, Alain Albrecht
更新时间: 2020-03-07
摘要: Assessing soil organic carbon (SOC) stocks is a methodological issue for SOC monitoring at regional scale but crucial for global agendas of SOC sequestration to mitigate climate change and reduce food insecurity. The '4 per mille Initiative: Soils for Food Security and Climate', highlighted agricultural soil as a major lever for climate action and the need to assess SOC stock at different spatial and temporal scale. Infrared spectroscopy appeared as a promising tool to address this methodological issue. This work aimed to evaluate the potential of visible-near-infrared (VNIR) and mid-infrared (MIR) spectroscopic measurement methods to predict SOC stock and its variables (SOC content and bulk density) in tropical volcanic soils of 'La Réunion' island. The diversity of agricultural soils of 'La Réunion' was captured in the sample set (n = 95) with soil orders such as Andosols, Cambisols and Ferralsols. Partial least squares regressions (PLSR) with leave-one-out cross validation were used to build prediction models. With RPD higher than 2, the present study showed good prediction accuracy of models by MIR and VNIR spectroscopy of SOC content, bulk density and SOC stock for measurements in the laboratory or in the field. Accurate and direct SOC stock predictions were achieved on dried and sieved soil samples with MIR spectroscopy (RPD = 2.25; R2cv = 0.80; RMSEcv = 0.69 KgC m−2) and VNIR spectroscopy (RPD = 2.74; R2cv = 0.87; RMSEcv = 0.61 KgC m−2) but also directly on cores in the field with VNIR spectroscopy (RPD = 3.29; R2cv = 0.91; RMSEcv = 0.51 KgC m−2). This unexpected ability to predict directly SOC stocks by infrared spectroscopy can be partly explained by the high SOC content coupled with the large variation of SOC content and bulk density, providing a large range for those variables, and then a higher predictability. Yet these results questioned the underlying drivers of the bulk density and SOC stock, both being largely physical parameters supposed to be hardly predictable by infrared spectroscopy. Analyses of mean spectra and regression coefficients, combined with amorphous product (Alo, Feo, Sio, Alp, Fep) prediction models, demonstrated that these were detected in the spectra and were the drivers of SOC stock accurate predictions by infrared spectroscopy. Short-range ordered minerals, especially allophanes, appeared as proxy of the bulk density, and amorphous products such as Alp and Fep indicated the presence of organo-mineral complexes involved in SOC storage. Such promising results for SOC stock predictions from near- and mid-infrared volcanic soil spectra, confirmed that VNIR and MIR diffuse reflectance spectroscopy are an appropriate tool, rapid, low cost and non-destructive, to study SOC stocks in tropical volcanic soils. Upscaling of SOC stocks across the agricultural soils of the island is now just a step ahead, following external validation with additional data to validate the robustness of the prediction models.

23340. 题目: Influence of soil forming factors on the molecular structure of soil organic matter and carbon levels
文章编号: N20030711
期刊: CATENA
作者: Marco A. Jiménez-González, Ana M. Álvarez, Pilar Carral, Gonzalo Almendros
更新时间: 2020-03-07
摘要: There is currently an active controversy about the variable influence of the factors involved in the total content and the quality of the soil organic matter (SOM), which translates into its resilience and stability against biodegradation, and importantly on the rates of release of CO2 into the atmosphere. The aim of this work is to study the molecular composition of SOM in contrasting environments in order to evaluate the extent to which such conditions may affect SOM characteristics in addition to the levels of soil organic C (SOC). Up to 33 soils from different environmental scenarios of Spain were analysed by pyrolysis combined with gas chromatography mass spectrometry (Py-GC/MS). The 193 major pyrolysis compounds released from the soils were included in a chemostatistical study based in discriminant analysis to assess the impact of classical soil forming factors (i.e., climate, vegetation and geological substrate) in SOM content and composition. Improved van Krevelen diagrams were used to facilitate the recognition of different patterns in SOM composition dependent on soil forming factors. The results showed that the molecular composition of SOM varies systematically according to environmental factors, with a decreasing influence in the order: climate > vegetation > geological substrate. In addition, the total levels of SOM were also different depending on the environmental scenarios on these soils, suggesting both qualitative and quantitative control of soil C sequestration.