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23561. 题目: Prediction of soil organic matter in northwestern China using fractional-order derivative spectroscopy and modified normalized difference indices
文章编号: N19110603
期刊: CATENA
作者: Zipeng Zhang, Jianli Ding, Jingzhe Wang, Xiangyu Ge
更新时间: 2019-11-06
摘要: Visible-near-infrared (Vis-NIR) spectroscopy makes it possible to estimate soil organic matter content (SOMC). Spectral pretreatment techniques have important significance in the quantitative analysis of SOMC. A total of 150 soil samples collected in northwestern China were used as data sets for calibration and validation. The SOMC values and reflectance spectra were measured in the laboratory. Fractional-order derivatives (FODs) (intervals of 0.05, range of 0–2) were used for soil spectral pretreatment, and a new three-band index (modified normalized difference index, MNDI) was constructed based on the band-optimization algorithm and the existing two-band exponential form (normalized difference index, NDI). Partial least square-support vector machine (PLS-SVM) models were calibrated using spectral parameters selected based on a single dimension (FOD), two-dimensional index (NDI) and three-dimensional index (MNDI) and subsequently applied to estimate SOMC. Three model evaluation parameters, namely, the coefficient of determination (R²), root mean squared error (RMSE), and ratio of performance to interquartile range (RPIQ), were used to evaluate the estimation accuracy of the models. The results showed that with increased derivative order, the spectral strength gradually decreased, but the spectral detail increased. Furthermore, the correlation between FOD spectra and SOMC was significantly enhanced in the visible region, with the most obvious effect in the 1.05- to 1.45-order range. The PLS-SVM modeling results showed that the sensitivity and estimation accuracy of SOMC increased with increasing spectral synergy (i.e., 1D (FOD) < 2D (NDI) < 3D (MNDI)). Among the models, MNDI exhibited the best model performance, yielding a validation R² and RPIQ of 0.846 and 3.396, respectively. The combination of FOD and MNDI could weaken the soil noise information and improve the prediction accuracy of SOMC. Furthermore, the three-dimensional index has strong application potential for estimating other biochemical parameters of soil using Vis-NIR spectroscopy.

23562. 题目: Polyethylene glycol-stabilized nano zero-valent iron supported by biochar for highly efficient removal of Cr(VI)
文章编号: N19110602
期刊: Ecotoxicology and Environmental Safety
作者: Huihui Wu, Wenxia Wei, Congbin Xu, Yue Meng, Wenrong Bai, Wenjie Yang, Aijun Lin
更新时间: 2019-11-06
摘要: In this study, polyethylene glycol (PEG)-stabilized nano zero-valent iron (nZVI) supported by biochar (BC) (PEG-nZVI@BC) was prepared to remedy Cr(VI) with high efficiency. The morphology, functional groups, and crystalline structure of PEG-nZVI@BC composites were characterized, revealing that when PEG was added, a large number of –OH functional groups were introduced, and nZVI was effectively dispersed on the BC surface with a smaller particle size. The results of Cr(VI) remediation experiments showed Cr(VI) removal rate by PEG-nZVI@BC (97.38%) was much greater than that by BC-loaded nZVI (nZVI@BC) (51.73%). The pseudo second-order and Sips isotherm models provide the best simulation for Cr(VI) removal experimental data, respectively. The main remediation mechanism of Cr(VI) was reduction and co-precipitation of Cr-containing metal deposits onto PEG-nZVI@BC. Ecotoxicity assessment revealed PEG-nZVI@BC (1.00 g/L) has little influence on rice germination and growth, but resisted the toxicity of Cr(VI) to rice. The modified Community Bureau of Reference (BCR) sequential extraction showed pyrolysis could increase the percentage of oxidizable and residual Cr and diminish the environmental risk of Cr release from post-removal composites.
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23563. 题目: From Land to the Ocean: The Interplay Between Allochthonous and Autochthonous Contribution to Particles in Nepheloid Layers of the Cariaco Basin, Venezuela
文章编号: N19110601
期刊: Journal of Geophysical Research: Biogeosciences
作者: Laura Lorenzoni, Robert C. Thunell, Claudia R. Benitez‐Nelson, Enrique Montes, Ramón Varela, Yrene Astor, Frank E. Muller‐Karger
更新时间: 2019-11-06
摘要: Lithogenic sediment input to the Cariaco Basin on the eastern Venezuelan shelf is controlled by small mountainous rivers (SMRs). The Cariaco Basin is also an area of high phytoplankton productivity as a result of strong Trade Wind‐driven coastal upwelling. Characterizing the sources that supply particulate organic carbon (POC) to the deep Cariaco Basin is important for interpreting the paleoclimate record stored in its sediments. We measured suspended POC in the four main rivers draining into the Caraiaco Basin, the Tuy, Unare, Neveri, and Manzanares, between September 2008 and September 2009 and conducted basin‐wide oceanographic cruises in September 2008 (rainy season) and March 2009 (upwelling season). Riverine concentrations of dissolved organic carbon (DOC) and POC in the four rivers were comparable to observations made in similar tropical SMR systems (POC was between 0.3–2 mg C l⁻¹; DOC was between 100–300 μM). Within the basin, the geochemical composition of surface particles and bottom nepheloid layers (BNLs) changed with season. During the rainy season, the isotopic composition of both surface particles and BNL was characteristic of continentally derived material (δ¹³C_org, approximately −30 to −26‰), while during upwelling, the composition shifted to values more typical of marine sources (δ¹³C_org, approximately −24 to −20‰). SMRs represent an important component of the global carbon budget, which are often overlooked in ocean carbon budgets and also in paleoclimate studies of coastal environments.

23564. 题目: A characterization of HULIS-C and the oxidative potential of HULIS and HULIS-Fe(II) mixture in PM2.5 during hazy and non-hazy days in Shanghai
文章编号: N19110507
期刊: Atmospheric Environment
作者: Senlin Lu, Myat Sandar Win, Junyang Zeng, Chuanhe Yao, Mengfei Zhao, Guangli Xiu, Yichun Lin, Tingting Xie, Yafeng Dai, Lanfang Rao, Luying Zhang, Shinich Yonemochi, Qingyue Wang
更新时间: 2019-11-05
摘要: Humic-like substances (HULIS) were isolated from PM2.5 in Shanghai. The oxidative potential and the cytotoxicity of the isolated HULIS and its Fe(II) binary mixtures were evaluated by using cell-free Dithiothreitol (DTT) and cellular 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. Our data showed that HULIS-C contents in spring during hazy and non-hazy days were relatively higher than in winter. Cell-free DTT and bioassay (reactive oxygen species (ROS) and MTT) results showed that higher ROS values were released from individual HULIS or SRFA (Suwannee River Fulvic Acid) compounds than HULIS-Fe(II) complexes and Fe(II) alone. In addition, DTT and ROS correlation results were in line with each other and the oxidative potentials of HULIS and its binary mixtures were strongly inter-correlated with carbonaceous components (WSOC, OC) in PM2.5. Dose-dependent MTT results revealed that cell mortality positively correlated with the mass concentrations of HULIS (10–50 μg/ml). In the HULIS-Fe(II) system, the ROS generation ability depended on the mixing time of HULIS-C with Fe(II), thus suggesting that the organic-metal complexation time and the Fenton reaction induced by Fe (II) play a role in the cell mortality rate.

23565. 题目: Systematic microbial production of optically active dissolved organic matter in subarctic lake water
文章编号: N19110506
期刊: Limnology and Oceanography
作者: Martin Berggren, Cristian Gudasz, Francois Guillemette, Geert Hensgens, Linlin Ye, Jan Karlsson
更新时间: 2019-11-05
摘要: The ecology and biogeochemistry of lakes in the subarctic region are particularly sensitive to changes in the abundance and optical properties of dissolved organic matter (DOM). External input of colored DOM to these lakes is an extensively researched topic, but little is known about potential reciprocal feedbacks between the optical properties of DOM and internal microbial processes in the water. We performed 28‐day dark laboratory incubation trials on water from 101 subarctic tundra lakes in northern Sweden, measuring the microbial decay of DOM and the resulting dynamics in colored (CDOM) and fluorescent (FDOM) DOM components. While losses in dissolved oxygen during the incubations corresponded to a 20% decrease in mean DOM, conversely the mean CDOM and total FDOM increased by 22% and 30%, respectively. However, the patterns in microbial transformation of the DOM were not the same in all lakes. Notably, along the gradient of increasing ambient CDOM (water brownness), the lakes showed decreased microbial production of protein‐like fluorescence, lowered DOM turnover rates and decreasing bacterial growth per unit of DOM. These trends indicate that browning of subarctic lakes systematically change the way that bacteria interact with the ambient DOM pool. Our study underscores that there is no unidirectional causal link between microbial processes and DOM optical properties, but rather reciprocal dependence between the two.

23566. 题目: Magnetic palm kernel biochar potential route for phenol removal from wastewater
文章编号: N19110505
期刊: Environmental Science and Pollution Research
作者: Muhammad Nazmi Hairuddin, Nabisab Mujawar Mubarak, Mohammad Khalid, Ezzat Chan Abdullah, Rashmi Walvekar, Rama Rao Karri
更新时间: 2019-11-05
摘要: The pollution of water resources due to the disposal of industrial wastes that have organic material like phenol is causing worldwide concern because of their toxicity towards aquatic life, human beings and the environment. Phenol causes nervous system damage, renal kidney disease, mental retardation, cancer and anaemia. In this study, magnetic palm kernel biochar is used for removal of phenol from wastewater. The effect of parameters such as pH, agitation speed, contact time and magnetic biochar dosage are validated using design of experiments. The statistical analysis reveals that the optimum conditions for the highest removal (93.39%) of phenol are obtained at pH of 8, magnetic biochar dosage of 0.6 g, agitation speed at 180 rpm and time of 60 min with the initial concentration of 10 mg/L. The maximum adsorption capacities of phenol were found to be 10.84 mg/g and Langmuir and Freundlich isotherm models match the experimental data very well and adsorption kinetic obeys a pseudo-second order. Hence, magnetic palm kernel can be a potential candidate for phenol removal from wastewater.

23567. 题目: Function of agricultural waste montmorillonite-biochars for sorptive removal of 17β-estradiol
文章编号: N19110504
期刊: Bioresource Technology
作者: Xin Tong, Linshu Jiang, Yanxia Li, Xingcai Chen, Yan Zhao, Boyang Hu, Fengsong Zhang
更新时间: 2019-11-05
摘要: Agricultural wastes of cow manure and wheat straw were used to prepare montmorillonite (Mt)-biochars (CMt and WMt) for sorptive removal of 17β-estradiol (E2) from aqueous solution. The E2 adsorption performance of the two Mt-biochars was investigated using systematic adsorption kinetics and isotherms. The results exhibited that the maximum E2 adsorption amount of CMt was 41.02 mg/g, while it was 62.89 mg/g for WMt. Meanwhile, intraparticle diffusion model demonstrated that intraparticle diffusion was not the only rate-limiting step, both film diffusion and intraparticle diffusion were involved in the diffusion process. Higher pH levels (>10) decreased the adsorption capacities of Mt-biochars for E2. However, the ionic strength and the background electrolytes did not significantly affect adsorption process. Moreover, the two Mt-biochars both exhibited excellent regeneration and reusability. These results provided a potential solution to the recycling of agricultural wastes and the problem of estrogen contaminant.
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23568. 题目: Study on the long-term effects of DOM on the adsorption of BPS by biochar
文章编号: N19110503
期刊: Chemosphere
作者: Xue Yang, Shiqiu Zhang, Le Liu, Meiting Ju
更新时间: 2019-11-05
摘要: Bisphenol S (BPS), regarded as a valid alternative to Bisphenol A (BPA), has been found to induce acute toxicity, genotoxicity. In this paper, BPS pollution was repaired by corn straw biochar, and the effect of dissolved organic matter (DOM) on the remediation mechanism was investigated. Different DOMs were obtained by decomposing corn straw in red soil, yellow soil and brown soil. The DOMs were characterized by Elemental analysis, Fourier infrared spectroscopy (FT-IR), ultraviolet–visible spectroscopy (Uv–vis) spectroscopy, Three-dimensional excitation-emission matrix (3D-EEM). Different kinds of DOMs were added into the biochar adsorption system to determine the optimal pH, optimal dosage, equilibrium adsorption capacity, adsorption kinetics, adsorption isotherms, thermodynamic characteristics, and explore the influence mechanism of DOM on the adsorption of BPS by biochar. The results of the adsorption experiments showed that DOM would suppress the BPS adsorption capacity on biochar. In addition, the DOM, produced by decomposition of corn straw with brown soil, had the strongest inhibitory effect on adsorption, and red soil was the soil with the lowest inhibitory effect on organic pollution removal by biochar.
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23569. 题目: Physical and biological removal of Microcystin-LR and other water contaminants in a biofilter using coated sand composites
文章编号: N19110502
期刊: Science of The Total Environment
作者: Pratik Kumar, Hadji Rehab, Krishnamoorthy Hegde, Satinder Kaur Brar, Maximiliano Cledon, Azadeh Kermanshahi-pour, Sung Vo Duy, Sébastien Sauvé, Rao Y. Surampalli
更新时间: 2019-11-05
摘要: Sand as a filter media is often challenged by the presence of organics in the form of natural organic matter, metal ions, and various micropollutants in the source water. It is mainly due to the presence of limited active adsorption sites and low surface area that governs an ineffective adsorption potential of the sand material. Herein, graphitized sand was synthesized to tackle the above limitations using two sugar solution sources: a) brewery effluent (as a low-cost solution) (GS1) and; b) sucrose solution (GS2). GS1 showed 68%, 60%, and 99% higher maximum adsorption constant (q_max) for divalent metal ions: iron, copper, and manganese, respectively as compared to raw sand (RS). Coating of MnO₂ over the graphitized sand (GSMs: GS1M and GS2M) further helped in Microcystin-LR (MC-LR) removal (3% - 9%) when inoculated with MC-LR-degraders, but was not as effective in removing metals, organic carbon and nitrogen when compared to just graphitized sand (GS1 or GS2). Inoculating GS and GSMs (for both sugar sources) not only helped in higher MC-LR removal (10%- 15% more) but also enhanced the removal of other water contaminants including metals, organic nitrogen, and carbon. GS1 showed 20% and 50% more MC-LR removal than the sand material when tested at a low and high initial concentration of MC-LR (5 µg/L and 50 µg/L). The highest breakthrough period was obtained for GS1 filter using 1 mg/L Rhodamine-B dye, which was 12 times (48 minutes) more than the raw sand filter and almost 2.5 times (second best, 21 minutes) than GS1M. After three cycles of regeneration and reuse of GS1 filter, a decrease of just 14 % in saturation adsorption capacity indicated its high reusability aspects.
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23570. 题目: Linking the molecular composition of autochthonous dissolved organic matter to source identification for freshwater lake ecosystems by combination of optical spectroscopy and FT-ICR-MS analysis
文章编号: N19110501
期刊: Science of The Total Environment
作者: Shasha Liu, Zhongqi He, Zhi Tang, Leizhen Liu, Junwen Hou, Tingting Li, Yahe Zhang, Quan Shi, John P. Giesy, Fengchang Wu
更新时间: 2019-11-05
摘要: Autochthonous dissolved organic matter (DOM) is increasingly released in lakes due to eutrophication, and thus affects the composition and environmental behaviors of DOM in eutrophic lakes. However, there are only limited studies on the molecular characteristics of autochthonous DOM and its influencing mechanisms. Herein, end-member DOM samples of macrophytes, algae, sediments and freshwater DOM samples in eutrophic lakes (Ch:Taihu and Dianchi) were collected and characterized by optical spectroscopy and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). The results revealed the chemical structures of autochthonous DOM were more aliphatic and less oxidized, which was marked by increases in lipid compounds and decreases in the lignin components as compared to the allochthonous DOM-dominated freshwaters. More specially, algae-derived DOM contains more lipid (56.8%) compounds, while macrophyte-derived DOM was dominated by lignin (50.6%) and tannin (17.4%) compounds. Sediment-derived DOM contained more N-containing compounds. The traditional optical indices indicated the relative aromaticity covaried with polyphenolic and polycyclic aromatics, whereas those reflecting autochthonous DOM covaried with more aliphatic compounds. Multivariate analysis of FT-ICR-MS data of end-members and freshwaters revealed the predominant terrestrial input to Lake Taihu and greater contribution of algae released DOM to Dianchi. This study provides critical information about the characteristics of autochthonous DOM at a molecular level and confirmed autochthonous DOM was compositionally distinct from allochthonous DOM. Overall autochthonous DOM should be gained more attention in the eutrophic lakes.
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23571. 题目: Characterization of the water masses in the shelf region of the Bering and Chukchi Seas with fluorescent organic matter
文章编号: N19110407
期刊: Journal of Geophysical Research: Oceans
作者: Youhei Yamashita, Yuki Yagi, Hiromichi Ueno, Atsushi Ooki, Toru Hirawake
更新时间: 2019-11-04
摘要: Pacific water is an important nutrient source for sustaining biological production in the Chukchi Sea, western Arctic Ocean, which is one of the productive regions in the world. Therefore, to understand the impacts of future environmental changes on biological production in the sea, it is crucial to understand the origins, modification processes, and spatiotemporal variations of the water masses from the Bering Sea with changes in nutrient concentrations. To improve water mass analysis in the shelf regions of the Bering and Chukchi Seas, we observed levels of humic‐like fluorescent organic matter (FOMH) by using an in situ fluorometer directly connected to a temperature‐salinity sensor during a cruise in the early summer of 2013 and evaluated the potential of FOMH as a third parameter of water mass analysis. The levels of FOMH were different among specific water masses in the region, and FOMH seemed to behave semi‐conservatively in the shelf regions of the Bering and Chukchi Seas during the early summer of 2013. The distributional pattern of FOMH implies that FOMH estimated by the in situ fluorometer has the potential to (1) separate warm water into riverine‐affected Alaskan Coastal Water and historically photobleached summer Bering Basin Water, (2) distinguish the Anadyr Water, which has low FOMH levels and high nutrient concentrations, from the Bering Shelf Water, and (3) determine different formation/modification processes of dense shelf water that contains high nutrient concentrations.

23572. 题目: Minimal biomass deposition in banded iron formations inferred from organic matter and clay relationships
文章编号: N19110406
期刊: Nature Communications
作者: Matthew S. Dodd, Dominic Papineau, Franco Pirajno, Yusheng Wan, Juha A. Karhu
更新时间: 2019-11-04
摘要: The cycling of iron and organic matter (OM) is thought to have been a major biogeochemical cycle in the early ferruginous oceans which contributed to the deposition of banded iron formations (BIF). However, BIF are deficient in OM, which is postulated to be the result of near-complete oxidation of OM during iron reduction. We test this idea by documenting the prevalence of OM in clays within BIF and clays in shales associated with BIF. We find in shales >80% of OM occurs in clays, but <1% occurs in clays within BIF. Instead, in BIF OM occurs with 13C-depleted carbonate and apatite, implying OM oxidation occurred. Conversely, BIF which possess primary clays would be expected to preserve OM in clays, yet this is not seen. This implies OM deposition in silicate-bearing BIF would have been minimal, this consequently stifled iron-cycling and primary productivity through the retention of nutrients in the sediments.

23573. 题目: Major ions and rare earth elements hydrogeochemistry of the Atibaia and Jaguari rivers subbasins (Southeast Brazil)
文章编号: N19110405
期刊: Applied Geochemistry
作者: Bruno Cesar Mortatti, Jacinta Enzweiler
更新时间: 2019-11-04
摘要: The rivers that comprise the Atibaia and Jaguari medium size subbasins and their interconnected reservoirs (Cantareira Water System) provide drinking water for about one-third of São Paulo's State population. Native vegetation covers nearly 30% of the catchments' territory, and the remaining comprises small-scale farming, reforestation, industries, and urban agglomerations. The study aimed to find at which extent the silicate rock lithologies, land uses, and the water transference between reservoirs influence the rivers' water composition. Forty-seven river water samples, collected before and after the dams during a rainy and a dry period, presented circumneutral pH values, while electric conductivity, major ions and dissolved organic carbon concentrations increased in the downstream direction, controlled by silicate weathering, noticeable anthropogenic inputs, and negligible seasonal influence. The water type is Na–Ca–HCO₃, the overall total dissolved solids (TDS) presented one order of magnitude difference between higher and lower reaches, and evidences of solute transference between the two subbasins. River water turbidity was higher during the rainy season and positively correlated with the ∑REE measured in the <0.22 μm pore filtered samples because of the dispersion of sediments (eroded soil) in the water bodies. We show that rock weathered material dispersed in water can increase the ∑REE and originate positive Ce anomalies in its filtrate, similar to features observed in normalized patterns in the river water samples. Most samples exhibited flat shale-normalized REE distributions, with less fractionation between light and heavy REE than the regional lithotypes. Most samples also presented positive Eu anomalies, which source are the rocks of the area. The more urbanized stretches of the rivers exhibited discrete anthropogenic Gd anomalies. The results of this study demonstrate increasing signatures from human activities in the water bodies.

23574. 题目: Signally Improvement of Polyurethane Adhesive with Hydroxy-enriched Lignin from Bagasse
文章编号: N19110404
期刊: Colloids and Surfaces A: Physicochemical and Engineering Aspects
作者: YinChen Chen, Shiyu Fu, Hui Zhang
更新时间: 2019-11-04
摘要: Acetic acid lignin (AAL) obtained from Bagasse was used as a partial substitute of polyols for polyurethane (PU) adhesive due to the presence of reactive sites, i.e. aliphatic and aromatic hydroxyl groups, in its structure. To improve its reactivity, lignin is partly demethylated before the copolymerization with polyisocyanate. The demethylation, catalyzed by hydrobromic acid solution under heating conditions, resulted in a decrease of methoxy groups on the phenyl ring and the increase of phenolic hydroxyl groups. It is found that 120 ℃ is the preferred temperature for the demethylation resulted in a 36.5% increase in hydroxyl content of lignin up to 5.25 mmol/g. Lignin-based polyurethane adhesives were prepared in two steps including preparing a prepolymer based on mixtures of toluene-2,4-diisocyanate (TDI) and unmodified or demethylated lignin, and then the polymerization was completed by adding polyethylene glycol (PEG). The mass ratio (1:1) of TDI: (lignin + PEG) in the compositions was here investigated. The results indicated that the presence of lignin (with and without demethylation) in polyurethane adhesives increased the glass transition temperature, Young’s modulus, and elongation at break. Particularly, the tensile strength was increased by 15-36 MPa with the addition of 10-30 wt% of lignin. Lignin with higher amount of hydroxyl groups prepared by partly demethylation is better integrated into the three-dimensional cross-linking networks of the covalent polymer as a substitute of polyols. Compared to those PU adhesives based on the raw AAL, the adhesives prepared by demethylated lignin have higher tensile strength and thermal stability. It indicates that the demethylation is effective and it is a good strategy to prepare lignin-based PU adhesive with favorable mechanical properties.
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23575. 题目: Validation of a coupled δ2Hn-alkane-δ18Osugar paleohygrometer approach based on a climate chamber experiment
文章编号: N19110403
期刊: Biogeosciences
作者: Johannes Hepp, Bruno Glaser, Dieter Juchelka, Christoph Mayr, Kazimierz Rozanski, Imke Kathrin Schäfer, Willibald Stichler, Mario Tuthorn, Roland Zech, and Michael Zech
更新时间: 2019-11-04
摘要: The hydrogen isotopic composition of leaf wax-derived biomarkers, e.g. long chain n-alkanes (δ²H_n-alkane), is widely applied in paleoclimatology research. However, a direct reconstruction of the isotopic composition of paleoprecipitation based on δ²H_n-alkane alone can be challenging due to the overprint of the source water isotopic signal by leaf-water enrichment. The coupling of δ²H_n-alkane with δ¹⁸O of hemicellulose-derived sugars (δ¹⁸O_sugar) has the potential to disentangle this effect and additionally allow relative humidity reconstructions. Here, we present δ²H_n-alkane as well as δ¹⁸O_sugar results obtained from leaves of the plant species Eucalyptus globulus, Vicia faba var. minor and Brassica oleracea var. medullosa, which were grown under controlled conditions. We addressed the questions (i) do δ²H_n-alkane and δ¹⁸O_sugar values allow precise reconstructions of leaf water isotope composition, (ii) how accurately does the reconstructed leaf-water-isotope composition enables relative humidity (RH) reconstruction in which the plants grew, and (iii) does the coupling of δ²H_n-alkane and δ¹⁸O_sugar enable a robust source water calculation

23576. 题目: Membrane fouling in integrated adsorption-UF system: Effects of NOM and adsorbent properties
文章编号: N19110402
期刊: Environmental Science: Water Research & Technology
作者: Kai Li, Shu Li, Ce Sun, Tinglin Huang, Guibai Li, Heng Liang
更新时间: 2019-11-04
摘要: The integration of adsorption with ultrafiltration (UF) is a promising technology for the production of high quality drinking water, but it is still under debate whether the addition of adsorbent can mitigate membrane fouling. This study was conducted to investigate the impact of properties of adsorbent and natural organic matter (NOM) in feed water on membrane fouling in the integrated adsorption-UF system. A continuous-flow hollow fiber UF set-up with periodic backwash and aeration was used to imitate the operation of full-scale integrated adsorption-UF systems. Two types of adsorbents, commercial powdered activated carbon (PAC) and homemade mesoporous adsorbent resin (MAR), were examined. As for Songhua River water dominated by allochthonous NOM, membrane fouling of PAC/UF system was increased by 39.5% compared with that of UF alone, whereas the addition of MAR mitigated membrane fouling by 66.4%. For the synthetic water composed of algal organic matter (AOM), membrane fouling of PAC/UF and MAR/UF systems were reduced by 40.7% and 83.3%, respectively. The results suggested that deposition of adsorbent particles and fouling resistance of cake layer was determined by hydrophobicity and molecular weight distribution of NOM as well as properties of adsorbents. This study highlights the significance of adsorbent selection for the integrated adsorption-UF process according to the source and properties of NOM.

23577. 题目: Performance and mechanisms of wastewater sludge conditioning with slag-based hydrotalcite-like minerals (Ca/Mg/Al-LDH)
文章编号: N19110401
期刊: Water Research
作者: Weijun Zhang, Haowan Cheng, Sainan Peng, Dandan Li, Hongyu Gao, Dongsheng Wang
更新时间: 2019-11-04
摘要: Extracellular polymeric substances (EPS) in wastewater sludge form a network structure that is highly hydrophilic and compressible. Thus chemical conditioning is always required to improve sludge dewaterability by changing the gelatinous structure of sludge flocs. Layered double hydroxides (LDH) are generally characterized by large surface area and high anion exchange capacity, so we prepared three types of hydrotalcite-like compounds (Ca/Mg/Al-LDHs) from a typical solid waste, blast furnace slag, using NaOH precipitation (giving LDH_a), a hydrothermal method (LDH_b), and NaOH–Na₂CO₃ precipitation (LDH_c). The physicochemical properties of the three LDH were comprehensively characterized, and their effectiveness as sludge conditioners was evaluated. The results showed that LDH conditioning was able to promote sludge dewaterability, and conditioning efficiency was strongly dependent on LDH structural properties. LDH neutralized the negative charges onto sludge particles and interacted with EPS to increase floc strength. LDH also formed a skeletal structure that reduced sludge compressibility. In addition, there were interactions between the LDH surfaces and the O=C–OH in EPS proteins, which altered the secondary structure of protein molecules, consequently increasing sludge dewaterability. The biomolecules of low-molecular-weight fractions (such as peptides and humic acids) in soluble EPS intercalated LDH. Both the surface complexation of organic matter containing carboxyl groups and the intercalation of small molecules in soluble EPS were responsible for EPS–LDH interactions. The combination of skeleton formation, electrostatic interaction, and EPS–LDH interactions resulted in compression of gel-like structure and improved sludge dewatering performance. We finally suggested a novel sludge treatment process that increases sludge dewaterability using slag-derived Ca/Mg/Al-LDH to condition the sludge, and it could be combined with pyrolysis to prepare multi-functional materials or bio-oil.
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23578. 题目: Can Humic Substances Improve Soil Fertility under Salt Stress and Drought Conditions?
文章编号: N19110313
期刊: Journal of Environment Quality
作者: Stella R. P. Suddarth, Jorge F. S. Ferreira, Lourival F. Cavalcante, Vânia S. Fraga, Ray G. Anderson, Jonathan J. Halvorson, Francisco T. C. Bezerra, Sherly. A. S. Medeiros, Cassio R. G. Costa, Nildo S. Dias
更新时间: 2019-11-03
摘要: Semiarid soils may be poor in organic carbon, a necessary source of energy for soil microorganisms that affect plant growth. Although the addition of organic carbon may improve soil chemical characteristics, the concentration of humic compounds in the organic component may vary and affect soil chemical composition. We evaluated the effect of two sources of humic compounds on a dystrophic yellow Oxisol cultivated with passion fruit (Passiflora edulis Sims f. edulis) and irrigated with saline water during a severe drought in the Brazilian semiarid region. Soil fertility was evaluated during two seasons. A bovine biofertilizer and an organic commercial amendment (Humistar) were used as sources of humic compounds. Salinity resulted in reduced soil fertility, mainly during the lower rainfall period. The combination of humic substances and salinity increased soil salinity. Humistar, more concentrated in humic acid than fulvic acid, increased both acidity and salinity of the Oxisol under study during the lower rainfall period. Our results contradict the general idea that organic matter can mitigate the harmful effects of salts in semiarid soils because the addition of organic sources to the soil, mainly during a severe drought period, may reduce soil fertility. Although this response may depend on the concentration of humic acids in the amendment, our results suggest that the correction of soil chemistry with the application of either amendment to Oxisols under semiarid conditions, mainly during severe drought, is not economically feasible.

23579. 题目: Potential Alterations in the Chemical Structure of Soil Organic Matter Components during Sodium Hydroxide Extraction
文章编号: N19110312
期刊: Journal of Environment Quality
作者: Xi Chen, Mengcan Jin, Yujun Xu, Wenying Chu, Daniel C. Olk, Jingwei Hu, Yanyu Jiang, Jingdong Mao, Hongjian Gao, Michael L. Thompson
更新时间: 2019-11-03
摘要: The use of alkaline solutions, especially 0.1 to 0.5 M NaOH solutions, for the extraction of humic substances (HS) from soils is controversial because of the potential for chemical and physical alteration of the organic materials in soils. Therefore, it is important to investigate the effects of NaOH extraction on the chemical structure of natural organic matter (NOM) in terrestrial ecosystems. By using solid-state nuclear magnetic resonance, we investigated the impact of NaOH and water extractions on the chemical structure of insoluble and extractable fractions of three model components of NOM: cellulose, van Soest lignin, and peat. We found both sp2–hybridized and carboxyl C groups occurred in the NaOH-extractable cellulose fraction relative to the bulk cellulose. Compounds solubilized from the lignin by treatment with 0.1 M NaOH were dominated by aromatic C-O, aromatic C, and OCH3 functional groups, indicating that some free phenolic monomers were extracted by the alkaline solution. Compared with the bulk peat, the concentration of COO/NCO and sp2–hybridized C in NaOH-reconstituted peat sample increased by 40 and 5%, respectively, whereas the concentration of carbohydrate C decreased by 14%. In summary, the chemical structures of cellulose, van Soest lignin, and the peat were altered to some extent by the 0.1 M NaOH extraction. These observations provide useful context in the consideration of potential alterations in chemical composition when one interprets results of HS extractions employing NaOH solutions. Future research will establish the proportion of these alterations that may result from an alternative, slower procedure for acidifying solutions after NaOH extraction.

23580. 题目: Lasting Effects of Wildfire on Disinfection By-Product Formation in Forest Catchments
文章编号: N19110311
期刊: Journal of Environment Quality
作者: Alex T. Chow, Kuo-Pei Tsai, Timothy S. Fegel, Derek N. Pierson, Charles C. Rhoades
更新时间: 2019-11-03
摘要: Severe wildfires often have dramatic short-term effects on water quality, although there is increasing evidence that in some catchments their effects can persist for many years. Forest recovery after the 2002 Hayman Fire burned catchments that supply drinking water to over a half million users in Denver, CO, has been extremely slow and has caused persistent water quality concerns. To evaluate whether postfire water quality changes increase the potential to form undesirable by-products of water disinfection, we compared stream water from eight burned catchments within the Hayman Fire and five adjacent unburned catchments. We tested dissolved organic carbon (DOC) concentrations and the formation of disinfection by-products (trihalomethanes [THMs], haloacetonitriles [HANs], chloral hydrate [CHD, and haloketones [HKTs]) in stream water monthly during 2014 and 2015. Stream DOC, THMs, and CHD and specific ultraviolet absorbance at 254 nm (SUVA254) were elevated in catchments with a moderate extent of high-severity wildfire (8–46% of catchment area) relative to catchments that were unburned and those that burned more extensively (>74% of catchment area) 14 yr after the fire. In contrast, formation of highly toxic but unregulated nitrogenous HANs increased linearly with wildfire extent. Although these findings should not raise concern regarding drinking water safety, they highlight the long-term influences of high severity wildfire on source water C content, composition, and treatability.