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23681. 题目: Biochar combined with compost to reduce the mobility, bioavailability and plant uptake of 2,2',4,4'-tetrabrominated diphenyl ether in soil
文章编号: N19042305
期刊: Journal of Hazardous Materials
作者: Leilei Xiang, Hongjie Sheng, Chenggang Gu, Redmile-Gordon Marc, Yu Wang, Yonrong Bian, Xin Jiang, Fang Wang
更新时间: 2019-04-23
摘要: Biochar application to soil is recognised for its capacity to immobilise pollutants (through sorption) while composted inputs can accelerate the biodegradation of organic pollutants. However, little is known about the influence of combined incorporation on plant uptake of organic pollutants. Therefore, we investigated the effects of maize straw-derived biochar (MSB), compost derived from maize straw and pig manure (SMC), and their combination (MSB-SMC) as soil amendments on bioavailability of 2,2',4,4'-tetrabrominated diphenyl ether (BDE-47) and carrot (Daucus carota L.) uptake in a horticultural soil. We found that biochar alone performed well in reducing BDE-47 bioavailability, but was less effective at degrading the pollutant. Conversely, addition of compost stimulated BDE-47 biodegradation. MSB-SMC enhanced BDE-47 biodegradation in soil, reduced contamination of carrot roots, and caused significant reductions in soil extractable BDE-47. The combination of contrasting approaches to remediation thus resulted in the most favorable outcome for a contaminated soil: immobilisation of contaminant from vegetable crops (via biochar) with simultaneous bioremediation of the growing medium. These findings point towards an effective strategy for reducing plant uptake of PDBEs through the combined use of biochar and compost as soil amendment – reducing mobility and facilitating degradation of the accessible contaminant fractions.
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23682. 题目: Carbon isoscapes of rodent diets in the Great Plains USA deviate from regional gradients in C₄ grass abundance due to a preference for C₃ plant resources
文章编号: N19042304
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Andrew W. Haveles, David L. Fox, Kena Fox-Dobbs
更新时间: 2019-04-23
摘要: Diet is an ecological attribute that species may adjust to cope with changing environments and may indicate how a population responds to changes in resource availability. In the Great Plains, plants utilizing the C₄ photosynthetic pathway may increase in abundance in the future because of their high tolerance for warm and dry environments, which are projected to increase. How increased C₄ abundance will influence grassland food webs remains unknown.Here, we evaluate how rodent diets vary relative to C₄ plant biomass at the regional scale of the southern Great Plains in the U.S. We measured δ¹³C values of hair from 534 individuals of 14 rodent species. Resulting isoscapes of δ¹³C values were statistically compared to three proxies for local abundance of C₄ grasses across the region.Overall, diets of most rodent species were dominated by C₃-derived resources with a few species relying on C₄ resources. Ordinary least squares linear regressions indicate that proxies for regional abundance of C₄ grasses explain very little of the variance in δ¹³C values in hair for the entire rodent community, however the isoscape of rodent hair δ¹³C values does broadly correspond to that for δ¹³C values of soil organic matter. The difference between median δ¹³C values of granivores and folivores is significantly and highly correlated with SOM δ¹³C values.Results from this study can be used as a baseline for characterizing dietary shifts in response to environmental change both in the geological past and in the future, and they identify which dietary categories may be most sensitive to future changes in the regional abundance of C₄ grasses.

23683. 题目: Synergistic effects of urban tributary mixing on dissolved organic matter biodegradation in an impounded river system
文章编号: N19042303
期刊: Science of The Total Environment
作者: Most Shirina Begum, Inae Jang, Jung-Min Lee, Han Bin Oh, Hyojin Jin, Ji-Hyung Park
更新时间: 2019-04-23
摘要: Dams and wastewater may greatly perturb riverine fluxes of dissolved organic matter (DOM) and CO₂, yet little is known about the relationships between altered DOM quality and CO₂ emission in eutrophic impounded river systems. A basin-wide field survey of surface water CO₂ and dissolved organic carbon (DOC) was combined with laboratory incubations to examine how dams and urban tributaries delivering treated wastewater influence longitudinal patterns in DOM properties and CO₂ along the impounded Han River traversing Seoul metropolitan area. Fluorescent DOM indices including parallel factor analysis (PARAFAC) components were used to characterize DOM in relation to biodegradable DOC (BDOC). Compared with distinct downstream increases in DOC and CO₂, BDOC concentration and its proportion in DOC (%BDOC) were highly variable along the mainstem and peaked at urban tributaries. Longitudinal increases in fluorescence index (FI), biological index (BIX), and two PARAFAC components (C2 and C3) contrasted with general decreases in humification index (HIX) and C1, reflecting increasing downstream inputs of anthropogenic DOM. During a 5-day incubation employing continuous CO₂ measurements, the cumulative production of CO₂ in the mainstem water mixed with urban tributary water was significantly higher than the level expected for conservative mixing of the two samples, indicating a synergistic enhancement of DOM biodegradation. Molecular formulas identified by Fourier transform-ion cyclotron resonance-mass spectrometry (FT-ICR-MS) revealed more consumed molecules in the mainstem water and more newly produced molecules in the tributary water over the 5-day incubation, implying abundant labile components in the mainstem water discharged from the upstream dam and highly processed tributary DOM limited in immediately biodegradable organic materials. Downstream increases in CO₂ and DOC along the Han River, combined with the synergistic effect observed in the mixed water, suggest that mixing wastewater-derived DOM with labile autochthonous DOM can enhance CO₂ production in the river system perturbed by impoundment and wastewater.
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23684. 题目: Sediment alkaline-extracted organic matter (AEOM) fluorescence: An archive of Holocene marine organic matter origins
文章编号: N19042302
期刊: Science of The Total Environment
作者: Carolina P. Funkey, Daniel J. Conley, Colin A. Stedmon
更新时间: 2019-04-23
摘要: Organic matter (OM) is comprised of a complex mixture of substrates, which are difficult to fully characterize. Therefore a range of analytical approaches is applied to provide a better understanding of the dynamics and biogeochemical cycling of aquatic system. One approach is UV–Visible spectroscopy, which includes measurements of spectral absorption and fluorescence of colored and fluorescent fractions of dissolved OM (DOM, CDOM and FDOM). In this study OM fluorescence is characterized by excitation-emission matrix spectroscopy on alkaline extracted DOM from a Baltic Sea sediment core that spanned 8500 years and fluctuating levels of hypoxia. Our results showed that three underlying fluorescence components had strong correlations with carbon, nitrogen content and δ¹⁵N. Our results demonstrate that optical properties of extracted OM from sediments reveal information about OM quality and quantity similar to those of biomarkers, which can be a useful additional tool for investigating OM deposition.
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23685. 题目: N₂ fixation impacted by carbon fixation via dissolved organic carbon in the changing Daya Bay, South China Sea
文章编号: N19042301
期刊: Science of The Total Environment
作者: Danyang Li, Jiaxing Liu, Run Zhang, Min Chen, Weifeng Yang, Junjie Li, Ziming Fang, Bo Wang, Yusheng Qiu, Minfang Zheng
更新时间: 2019-04-23
摘要: We present the first concurrent measurements of N₂ fixation rates (¹⁵N₂ uptake), primary production (¹⁴C uptake), dissolved organic carbon (DOC) concentrations, and diazotrophic community composition derived from nitrogenase (nifH) abundance in the subtropical Daya Bay (DB) of the coastal northern South China Sea (NSCS) from 2015 to 2017. N₂ fixation rates ranged from n.d. - 4.51 nmol N L⁻¹ h⁻¹. Such values were generally higher than those reported in the neighbouring NSCS open waters and several well-studied oligotrophic waters, thereby suggesting that N-replete conditions do not prevent N₂ fixation in coastal waters. N₂ fixation rates were positively and significantly correlated with the primary production and the concentration of DOC in DB in the spring and summer. Combined with other lines of evidence, we suggest that N₂ fixation may be facilitated by non-diazotrophic phytoplankton via a probable regulation of the quantity and quality (bioavailability) of DOC in DB. Since DB represents a suitable site that has experienced dramatic human-induced changes in environmental conditions, our results likely provide insights in understanding how N₂ fixation and relevant biogeochemical processes may respond to intensified global anthropogenic forcing in similar coastal settings.
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23686. 题目: Revealing the impact of pyrolysis temperature on dissolved organic matter released from the biochar prepared from Typha orientalis
文章编号: N19042203
期刊: Chemosphere
作者: Haiming Wu, Yanshan Qi, Lu Dong, Xin Zhao, Hai Liu
更新时间: 2019-04-22
摘要: Biochars derived from wetland biomass have been extensively applied in water and wastewater treatments. This study investigated the quantity and chemical quality of dissolved organic matter (DOM) released from the biochar prepared from the typical wetland plant (Typha orientalis) at different pyrolysis temperatures (300–700 °C) by using fluorescence excitation-emission (EEM) spectrophotometry with parallel factor analysis (PARAFAC) and UV–Visible spectroscopy. The results showed that the content of DOM released from biochars at low pyrolysis temperatures (300–500 °C) was higher than that observed at high pyrolysis temperatures (600–700 °C). The distribution of DOM components (mainly including three humic acid-like substances, one fulvic acid-like substance and one tyrosine-like substance) varied significantly due to the increase of pyrolysis temperatures. The fulvic acid-like material was the key DOM component at the low pyrolysis temperature while the humic acid-like material became dominant at the high temperature. DOM quality indices also indicated that the percentage of the low molecular-weight DOM increased with the decreasing DOC concentration due to the higher temperatures. The results obtained in this study would be beneficial to guide the rational application of biochars in waste treatments.
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23687. 题目: Fate of Triclocarban (TCC) in aquatic and terrestrial systems and human exposure
文章编号: N19042202
期刊: Chemosphere
作者: Vimalkumar Krishnamoorthi, Sangeetha Seethappan, Arivalagan Pugazhendhi
更新时间: 2019-04-22
摘要: Triclocarban(TCC) is considered as contaminant of emerging concern (CEC), and ranked in the top 10 CEC occurrence. TCC is a high production volume synthetic chemical used extensively in various personal care products. This chemical will be released into the environment via incomplete wastewater treatment and untreated wastewater discharge. TCC and its transformation products (4,4’-dichlorocarbilide (DCC),1-(3-chlorophenyl)-3-phenylurea (MCC) and carbanilide (NCC),2’-OH-TCC, 3’-OH-TCC) were detected in the environmental matrices. Sediment organic carbon will influence TCC concentrations in suspended and bed sediments. TCC is an antimicrobial agent and also emerging endocrine disruptor that can cause immune dysfunction and affect human reproductive outcomes. Furthermore, TCC alters the expression of proteins related to binding and metabolism, skeletal muscle development and function, nervous system development and immune response. TCC has potential health risks in wildlife and humans. Several animal studies illustrate that it can cause various adverse effects, which can be monitored by antioxidant biomarkers (CAT, GST and LPO). Accumulation of TCC in organisms depends on the lipophilicity and bioavailability of TCC in sediment and water. TCC was continuously detected in aquatic system. TCC is a lipophilic compound, which can efficiently bind with lipid content. Women are more vulnerable to TCC due to substantially higher frequency and extended exposure to TCC. This review provides basic information of occurrence of TCC and the exposure levels in aquatic organisms. Several literatures have shown the higher usage and human exposure levels of TCC, which provides useful information for the chemical management approaches.

23688. 题目: Effect of co-existing Co²⁺ ions on the aggregation of humic acid in aquatic environment: Aggregation kinetics, dynamic properties and fluorescence spectroscopic study
文章编号: N19042201
期刊: Science of The Total Environment
作者: Liqiang Tan, Chaofeng Zhao, Xiaoli Tan, Xin Wang, Jinghua Feng, Ming Fang, Yuejiex Ai, Tasawar Hayat, Lu Sun, Xiangke Wang
更新时间: 2019-04-22
摘要: The fate and transport of humic substances in the aquatic environments depend significantly on their interactions with co-existing ions. Herein, we employed dynamic light scattering (DLS) measurement, molecular dynamic (MD) simulation and fluorescence spectrometry to investigate the aggregation of humic acid (HA) in the presence of Co²⁺ ions. The aggregation kinetics was depicted by hydrodynamic diameter (<D_h>) and the attachment efficiency (α) of HA aggregates. α increases gradually in the reaction-limited (slow) regime due to the decrease of the double layer repulsion, and the energy barrier is eliminated to a certain extent in the diffusion-limited reaction while α close to unity. The complexation between functional groups (i.e. carboxylic and phenolic groups) of HA and Co²⁺ ions contributes significantly to the aggregation process of HA. MD simulation and density functional theory (DFT) calculation demonstrate that the aggregation process of HA can be promoted by Co²⁺ through several inter- or intra-molecular interactions between HA and the Co²⁺ ions. The results provide a pathway for insight into the interactions between HA and metal ions, which is important for deeply understanding the environmental behaviors of HA in natural aqueous systems.
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23689. 题目: Phytoplankton growth and stoichiometric responses to warming, nutrient addition and grazing depend on lake productivity and cell size
文章编号: N19042110
期刊: Global Change Biology
作者: Marika A. Schulhof, Jonathan B. Shurin, Steven A.J. Declerck, Dedmer B. Van de Waal
更新时间: 2019-04-21
摘要: Global change involves shifts in multiple environmental factors that act in concert to shape ecological systems in ways that depend on local biotic and abiotic conditions. Little is known about the effects of combined global change stressors on phytoplankton communities, and particularly how these are mediated by distinct community properties such as productivity, grazing pressure and size distribution. Here, we tested for the effects of warming and eutrophication on phytoplankton net growth rate and C:N:P stoichiometry in two phytoplankton cell size fractions (<30μm and >30μm) in the presence and absence of grazing in microcosm experiments. Because effects may also depend on lake productivity, we used phytoplankton communities from three Dutch lakes spanning a trophic gradient. We measured the response of each community to multifactorial combinations of temperature, nutrient, and grazing treatments and found that nutrients elevated net growth rates and reduced carbon:nutrient ratios of all three phytoplankton communities. Warming effects on growth and stoichiometry depended on nutrient supply and lake productivity, with enhanced growth in the most productive community dominated by cyanobacteria, and strongest stoichiometric responses in the most oligotrophic community at ambient nutrient levels. Grazing effects were also most evident in the most oligotrophic community, with reduced net growth rates and phytoplankton C:P stoichiometry that suggests consumer‐driven nutrient recycling. Our experiments indicate that stoichiometric responses to warming and interactions with nutrient addition and grazing are not universal but depend on lake productivity and cell size distribution.

23690. 题目: Co-pyrolysis of sewage sludge and cotton stalks
文章编号: N19042109
期刊: Waste Management
作者: Zhipu Wang, Like Xie, Kai Liu, Jian Wang, Henan Zhu, Qiang Song, Xinqian Shu
更新时间: 2019-04-21
摘要: Proper disposal of ever-increasing amounts sewage sludge and cotton stalks is a challenge around the world, and conversion of these wastes into biochars via co-pyrolysis may be a promising solution. In this study, biochars were prepared via co-pyrolysis of sewage sludge and cotton stalks with different mixing ratios (cotton stalks/sewage sludge, w/w) at 650 °C for 2.0 h, and then, biochars were characterized to identify their potential agronomic and environmental benefits as soil amendments. Biochars prepared with higher mixing ratios had higher C contents and lower H/C and N/C ratios, which suggests that this approach has potential for improving C storage in biochar-treated soils to help offset greenhouse gas emissions. All biochars were mesoporous materials with an average pore size of 3–4 nm. The specific surface area increases indicated that these biochars would have relatively high water holding capacities and heavy metal adsorption capacities in heavy metal contaminated soils. The high ash contents and cation exchange capacity values in biochars prepared with lower mixing ratios indicate that these products would be useful for enhancing the nutrient supply and nutrient retention capacity in degraded soils. Moreover, the addition of more cotton stalks efficiently decreased the mobility and bioavailability of heavy metals in the biochars. At a certain level, co-pyrolysis of sewage sludge and cotton stalks to produce biochars would have both economic and environmental benefits.

23691. 题目: Fabrication of Graphene Oxide incorporated Polyethersulfone Hybrid Ultrafiltration Membranes for Humic Acid Removal
文章编号: N19042108
期刊: Separation and Purification Technology
作者: Mohammad Saad Algamdi, Ibrahim Hotan Alsohaimi, Jenny Lawler, Hazim M. Ali, Abdullah Mohammed Aldawsari, Hassan M.A. Hassan
更新时间: 2019-04-21
摘要: In this study, hybrid polyethersulfone membranes incorporated with graphene oxide were synthesized by a non-solvent induced phase separation approach. The influence of graphene oxide content on the membrane efficiency and fouling durability was elucidated, with emphasis on water flux, natural organic matter (NOM) rejection using humic acid as a model for NOM, and flux reduction due to fouling. The results revealed that the water flux increased with increasing GO content. It is worth noting that the MGO-5 membrane exhibits the highest J_w value (340 L m^-2 h^-1) among all the fabricated membrane, while the greatest J_HA (193.78 L m^-2h^-1) value was obtained for MGO-3 membrane. NOM rejection was improved significantly by the incorporation of GO. The best rejection value of HA solution using the membranes was observed for MGO-3 at pH 7. The presence of GO also improved the membrane reusability and antifouling capabilities, due to the enhancement of the hydrophilicity of the GO-membrane surface.

23692. 题目: Temperature sensitivity of soil organic matter decomposition in response to land management in semi-arid rangelands of Iran
文章编号: N19042107
期刊: CATENA
作者: Behzad Behtari, Zeinab Jafarian, Hosseinali Alikhani
更新时间: 2019-04-21
摘要: The biotic and abiotic factors can alter the temperature sensitivity of soil organic matter (SOM) decomposition in rangeland areas. This is a key issue that directly affects soil fertility and productivity. On the other hand, most of the rangelands in Iran are involved overgrazing. However, there is a lack of information about these effects, especially, in semi-arid environments. Therefore, the aim of this study was to assess the effect of land management on soil nutrient contents and their stoichiometry on the temperature sensitivity of SOM decomposition (Q₁₀) in semi-arid rangeland ecosystems. Soil samples (at three different soil depths) were collected in adjacent rangeland areas with different management in Iran. Soils were incubated at three different temperatures. The soil heterotrophic respiration was measured using an Alkali absorption method and then was calculated Q₁₀. The decrease in Q₁₀ values was observed with increasing carbon (C), nitrogen (N) and phosphorus (P) of soil content. Changes of Q₁₀ in relation to stoichiometry C:N and P:N showed a linear model and a second-order polynomial model in grazed and ungrazed rangeland respectively. Ungrazed rangeland had the lower Q₁₀ value (0.97) compared to grazed rangeland (1.21). Labile C variability at soil due to effects in land management such as trampling and erosion, altering plant biomass and microbial communities may be able to partly explained variation of Q₁₀ values. Overall, trend of decreasing Q₁₀ values associated with increasing C, N and P contents of soil in all rangeland management can be explained by the high microbial CUE. The obtained results presumably indicated that stoichiometry of C:P:N can play as an important determinant in increase CUE and decrease Q₁₀ in rangeland ecosystems. Overall, the results of this research will valuable for prediction of the condition and succession trend via Q₁₀ and C losses in various grazing management in semi-arid rangeland ecosystems.

23693. 题目: Detection of new long-chain mid-chain keto-ol isomers from marine sediments by means of HPLC APCI-MS and comparison with long-chain mid-chain diols from the same samples
文章编号: N19042106
期刊: Organic Geochemistry
作者: Gerard J.M. Versteegh, Julius Lipp
更新时间: 2019-04-21
摘要: Long-chain mid-chain-keto-1-ol positional isomers in sediments provide important information on past environments. Unfortunately, we are unable to assess their full potential since conventional GC–MS analysis of sediment extracts is unable to reliably qualify and quantify long-chain mid-chain-keto-1-ol positional isomers, especially if these are of minor abundance. Here, we use NP-HPLC–APCI-MS to separate these isomers at baseline resolution for a given chain-length, providing a reliable alternative method to detect and quantify these molecules. We detected unknown saturated and unsaturated long-chain mid-chain-keto-1-ols and suggest that the C_32:1 keto-ol has the keto-group at the C₁₄ position on the basis of the patterns of abundance and retention times. Based on dissimilarities in isomer composition with that of the long-chain mid-chain diols, obtained from the same analysis, we reject the hypothesis that diagenetic oxidation of the mid-chain diol functionality is the major source of the long-chain mid-chain-keto-1-ols. We rather favor the hypothesis that the keto-ols are predominantly produced by currently uncharacterized source organisms.

23694. 题目: Effect of multiple iron-based nanoparticles on availability of lead and iron, and micro-ecology in lead contaminated soil
文章编号: N19042105
期刊: Chemosphere
作者: Dinghua Peng, Bin Wu, Hang Tan, Siyu Hou, Min Liu, Hao Tang, Jiang Yu, Heng Xu
更新时间: 2019-04-21
摘要: Although iron nanoparticles (NPs) have been used for environmental remediation of heavy metal, their potential to remediate lead (Pb) contaminated soil and effect on soil micro-ecology is unclear. The purpose of this study was to investigate the potential of nanoscale zerovalent iron (nZVI), nanoscale zerovalent iron supported by biochar (nZVI@BC), ferrous sulfide (FeS-NPs), ferrous sulfide supported by biochar (FeS-NPs@BC), ferriferrous oxide (Fe₃O₄-NPs) and ferriferrous oxide supported by biochar (Fe₃O₄-NPs@BC) to remediate Pb contaminated soil and the influences for soil micro-ecology. The results showed that biochar (BC) could improve the crystal shape and superficial area of iron-based nanoparticles. Soil pH values was significantly decreased by FeS-NPs and FeS-NPs@BC, but increased by other iron-nanoparticles. The ability to reduce available Pb concentration showed significant difference among these iron-nanoparticles, that is, the immobilized rate were nZVI by 45.80%, nZVI@BC by 54.68%, FeS-NPs by 2.70%, FeS-NPs@BC by 5.13%, Fe₃O₄-NPs by 47.47%, Fe₃O₄-NPs@BC by 30.51% at day 90. Almost all soil enzyme activities in Fe₃O₄-NPs and Fe₃O₄-NPs@BC groups were increased, but the majority of the enzyme activities were inhibited in other iron-based nanoparticles groups, while the maximum bacterial number was determined in FeS-NPs group. Furthermore, microbial diversity analysis showed that FeS-NPs has significantly changed microbial community richness and diversity, followed by nZVI and Fe₃O₄-NPs. Accordingly, our results suggested that nZVI@BC had the best immobilization effect on Pb in high-concentration Pb-contaminated alkaline soil, but the toxic effect of Fe₃O₄-NPs on soil micro-ecology was relatively minimal.
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23695. 题目: Development of correlation spectroscopy (COS) method for analyzing fluorescence excitation emission matrix (EEM): A case study of effluent organic matter (EfOM) ozonation
文章编号: N19042104
期刊: Chemosphere
作者: Huarong Yu, Fangshu Qu, Xiaolei Zhang, Senlin Shao, Hongwei Rong, Heng Liang, Langming Bai, Jun Ma
更新时间: 2019-04-21
摘要: Two-dimensional correlation spectroscopy (2DCOS) has been used as a powerful tool for analyzing spectral features, but it has never been applied to fluorescence excitation-emission matrix (EEM) data due to the incompatible dimensions. This study first investigated EEM-COS by reducing the dimensions of the EEM (using parallel factor analysis, PARAFAC) for fitting to 2DCOS (EEM-PARAFAC-COS). The fluorescence changes of effluent organic matter (EfOM) during ozonation were studied using EEM-COS and synchronous fluorescence (SF)-2DCOS. The conventionally used SF-2DCOS proved to be biased due to the intrinsic drawback of SF, while the EEM-PARAFAC-COS gave accurate and trustworthy results. Homo-EEM-PARAFAC-COS indicated that the fluorescence protein-like and fulvic-like substances in EfOM were preferentially ozonated compared to humic-like substances. Hetero-EEM-PARAFAC-COS analyses on the EEM, FTIR, UV–vis absorbance, and size-exclusion chromatography showed that the fluorescence protein-like and fulvic-like substances in EfOM were associated with lower molecular weight (MW, ∼0.95 kDa), UV absorbance at ∼280 nm, and more electron-enriched aromatics (with amide and phenolic groups), which explained their ozonation preference, while humic-like substances were related to carboxylic groups, UV absorbance at ∼255 nm, and organics at MW of ∼4.50 kDa. This work demonstrated the great potential of EEM-PARAFAC-COS in studying fluorescence change and correlating fluorescence with other spectra.
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23696. 题目: Aquatic behavior and toxicity of polystyrene nanoplastic particles with different functional groups: Complex roles of pH, dissolved organic carbon and divalent cations
文章编号: N19042103
期刊: Chemosphere
作者: Fan Zhang, Zhuang Wang, Se Wang, Hao Fang, Degao Wang
更新时间: 2019-04-21
摘要: Herein we systematically examined the roles of water chemistry (pH, dissolved organic carbon (DOC), and divalent cations) and particle surface functionality that control the aqueous stability, aggregation, and toxicity of engineered nanoplastic particles in simulated natural environmental conditions. Model polystyrene latex nanoparticles (PLNPs) with three different functional groups, namely unmodified (uPLNPs), amine-modified (aPLNPs), and carboxyl-modified (cPLNPs), were investigated. Results indicate that the presence of only DOC increased the surface charge and exhibited negligible effects on the size distribution of the PLNPs in aqueous suspensions. The presence of the divalent cations (Ca²⁺ and Mg²⁺) was observed to decrease the surface charge and increase the size of the PLNPs. The coexistence of DOC and the divalent cations enhanced the extent of aggregation of the PLNPs in the water columns. The surface modification and pH were sensitive factors influencing the stability of PLNPs during long-term suspension when DOC and the divalent cations coexisted. Direct visual further testified the conclusions on the combined effects of solution and surface chemistry parameters. Furthermore, in situ transmission electron microscope observations revealed that the enhancement of PLNP aggregation in the presence of DOC and the divalent cation was caused by bridge formation. Toxicity test indicated the PLNPs exhibited acute toxicity and physical damage to Daphnia magna. The more complex the solution conditions, the more toxicity the aPLNPs and cPLNPs. Analysis of mode of toxic action implied that the PLNPs mainly caused the accumulation of oxidative damage to the gut of D. magna.

23697. 题目: Contrasting photoreactivity of β2-adrenoceptor agonists Salbutamol and Terbutaline in the presence of humic substances
文章编号: N19042102
期刊: Chemosphere
作者: Lei Zhou, Mohamad Sleiman, Ludovic Fine, Corinne Ferronato, Pascal de Sainte Claire, Emmanuelle Vulliet, Jean-Marc Chovelon, Guangli Xiu, Claire Richard
更新时间: 2019-04-21
摘要: The photodegradation reactions of two typical β2-adrenoceptor agonists, salbutamol (SAL) and terbutaline (TBL), alone, and in the presence of Aldrich humic acid (AHA) or Suwannee River fulvic acid (SRFA) were investigated by steady-state photolysis experiments, laser flash photolysis (LFP), kinetic modeling and quantum calculation. AHA and SRFA (2–20 mgC L⁻¹) accelerated the phototransformation of both SAL and TBL. For SAL, an inhibiting effect of oxygen on the photodegradation was observed that is fully consistent with the main involvement of excited triplet states of HS (³HS*). On the contrary, oxygen drastically enhanced the photodegradation of TBL showing that ³HS* were negligibly involved in the reaction. The involvement of singlet oxygen was also ruled out because of the low reaction rate constant measured between TBL and singlet oxygen. Quantum calculations were therefore performed to explore whether oxygenated radicals could through addition reactions explain the differences of reactivity of TBL and SAL in oxygen medium. Interestingly, calculations showed that in the presence of oxygen, the addition of phenoxyl on TBL led to the formation of adducts and to the loss of TBL while the same addition reaction on SAL partly regenerated the starting compound and at the end degraded SAL less efficiently. This study is of high relevance to understand the processes involved in SAL and TBL phototransformation and the photoreactivity of HS. Moreover, our findings suggest that TBL might be a promising probe molecule to delineate the role of oxygenated radicals.
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23698. 题目: Changes in dissolved organic matter composition and dynamics in a subtropical mangrove river driven by rainfall
文章编号: N19042101
期刊: Estuarine, Coastal and Shelf Science
作者: Morimaru Kida, Mai Tanabe, Mitsutoshi Tomotsune, Shinpei Yoshitake, Kazutoshi Kinjo, Toshiyuki Ohtsuka, Nobuhide Fujitake
更新时间: 2019-04-21
摘要: Dissolved organic matter (DOM) plays an important role in sustaining ecosystem services of mangrove forests through well-described biogeochemical and ecological functions. This study was conducted in the Fukido River (Ishigaki Island, Japan) to better understand the seasonal and episodic changes in DOM concentration and composition in a subtropical mangrove system. Water samples were collected seasonally along a headwater–mangrove–sea transect on 10 occasions from September 2014 through June 2016. DOM was fractionated based on hydrophobicity into two fractions (hydrophobic and hydrophilic) and also analyzed by excitation-emission matrix spectroscopy combined with parallel factor analysis (PARAFAC). Although seasonal changes in DOM concentration and composition were not observed, both hydrophobic and hydrophilic DOM concentrations and levels of the identified three PARAFAC components clearly increased during a typhoon event. It is suggested that episodic increases in freshwater input due to a typhoon caused enhanced leaching of DOM from mangrove litter and dissolution of mangrove soil organic matter (SOM), which was otherwise retained in the mangrove soil by salinity-induced aggregation. The aggregation–dissolution properties of SOM are crucial in determining the magnitude of DOM outwelling and possibly SOM accumulation rate by enhancing advective DOM exchanges. Future studies are needed to evaluate the size of the carbon pool and outwelling of DOM after classifying mangrove forests based on the hydrological regime that influences biogeochemical conditions in the forests.

23699. 题目: Using a coupled geochemical/physical mass balance model to gain insights into the deposition of subrecent evaporites: Searles Valley, California, USA
文章编号: N19042007
期刊: Journal of Paleolimnology
作者: Joseph J. Janick, Robert V. Demicco
更新时间: 2019-04-20
摘要: Modern and ancient saline lakes are important sites for the deposition of carbonates and evaporites. Here we describe a generalized computer model of chemical sediment production in a closed-basin lake subject to: (1) variable inflow sources through time; (2) variable volumes of these inflows; (3) variable temperature, and; (4) variable evaporation rates through time. We then apply our model to gain insights into some aspects of late Pleistocene evaporite deposits beneath Searles Lake, California, a well-described chemical sedimentary deposit. We tuned our model to match the masses and proportions of the major saline minerals trona and halite deposited in layers circa 32 ka to 24 ka. However, we could not reproduce the thicknesses of mixed siliciclastic, carbonate and organic layers sandwiched between the evaporites. The model is useful for interpreting and constraining the environmental conditions in and around any ancient saline lakes during evaporite deposition where the amounts, mineralogies, and vertical distribution of chemical sediments are known.

23700. 题目: The properties and removal efficacies of natural organic matter fractions by South African drinking water treatment plants
文章编号: N19042006
期刊: Journal of Environmental Chemical Engineering
作者: Welldone Moyo, Nhamo Chaukura, Titus A.M. Msagati, Bhekie B. Mamba, Sebastian G.J. Heijman, Thabo T.I. Nkambule
更新时间: 2019-04-20
摘要: This study presents an investigation on the fate of natural organic matter (NOM) and its dynamics throughout the treatment train at various drinking water treatment plants (WTP) in South Africa. The characteristics, concentration and removal efficiencies of NOM at various treatment stages on the basis of dissolved organic carbon, UV absorbance, specific ultra-violet absorbance, spectroscopic indices, maximum fluorescence intensity (Fmax), and polysaccharides removal, were studied. The highest polysaccharide concentration was in coastal plants compared to inland plants for the raw water samples. A Parafac model fitting four components was established for the raw waters, and validated based on the split half criteria. The Fmax values of the components was higher for terrestrial humic-like component (C1) and fulvic-like component (C2) than for humic-like components (C3), and for protein-like component (C4). Strikingly, the mean Fmax values for C2 and C3 were higher for plants located on the south west coast of South Africa than the plants located inland. While the humification index and UV254 removal correlated (R2 = 0.797), the correlation between the freshness index (β:α) and UV254 removal was also mild (R2 = 0.787). The removal efficiencies of bulk NOM were higher than for FNOM in the rapid sand filtration (RSF) stage, regardless of the location of the plants, suggesting that the RSF process is more efficient in removing non-fluorescent NOM than FNOM fractions. This study demonstrated the capability of optical methods in characterizing the fate, occurrence and removal of NOM in surface waters.