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24721. 题目: Recycling organic residues in soils as amendments: Effect on the mobility of two herbicides under different management practices
文章编号: N18072205
期刊: Journal of Environmental Management
作者: J.M. Marín-Benito, V. Barba, J.M. Ordax, M.J. Sánchez-Martín, M.S. Rodríguez-Cruz
更新时间: 2018-07-22
摘要: The addition of organic residues to soil to increase its organic matter content is considered as a viable option for sustainable food production in soils sensitive to degradation and erosion. However, the recycling of these organic residues in agricultural soils needs to be previously appraised because they can modify the behaviour of pesticides when they are simultaneously applied in agricultural practices. This study evaluated the changes in the mobility and persistence of two herbicides, triasulfuron and prosulfocarb, after two repeated applications in field experimental plots in an unamended soil and one amended with green compost (GC) for seven months. Different factors were studied: i) soil without amendment (S), ii) soil amended with two doses of GC ( 12 t C ha-1, S + GC1 and 40 t C ha 1, S + GC2), and iii) soils unamended and amended with different irrigation conditions: non-irrigated and with additional irrigation (2.8 mm per week). After the first application of herbicides, the results initially indicated no significant effects of soil treatments or irrigation conditions for triasulfuron mobility in agreement with the residual concentrations in the soil profile. The effect of irrigation was noted after one month of herbicide application and the effect of the soil treatment was significant after two months because the persistence of triasulfuron in S + GC2 was maintained until 50% of the applied amount. For prosulfocarb, the influence of soil amendment was significant for the initial persistence of the herbicide in S + GC2, higher than in S or S + GC1, in agreement with its adsorption constants for this soil. However, dissipation or leaching of the herbicide over time was not inhibited in this soil. After the repeated application of herbicides, the influence of the treatment of soils and/or irrigation was significant for the leaching and dissipation of both herbicides. The initial dissipation/degradation or leaching of herbicides was higher than after the first application, although persistence was maintained after five months of application in amended soils for triasulfuron and in unamended and amended soils for prosulfocarb. The results confirm that high doses of GC increased the persistence of both herbicides. This practice may offer the possibility of applying a tailored dose of GC to soil for striking a balance between residual concentrations and the soil agronomic effect.

24722. 题目: Soil C and N dynamics and their non-additive responses to litter mixture under different moisture conditions from an alpine steppe soil, Northern Tibet
文章编号: N18072204
期刊: Soil Biology and Biochemistry
作者: Youchao Chen, Shuqin Ma, Jing Liu, Genwei Cheng, Xuyang Lu
更新时间: 2018-07-22
摘要: Although there is a strong consensus that biodiversity can influence ecosystem functioning, how litter diversity affects soil ecological processes in different climatic contexts has been rarely studied. Here, we employed a mixed-litters’ experiment to examine how mixed-litters decomposition affects soil carbon (C) and nitrogen (N) dynamics under different moisture conditions from an alpine steppe soil in Northern Tibet. Litter of alpine steppe species, in monoculture or combination, were mixed with soil in 20%, 30% and 40% water holding capacities (WHC) in microcosms. During each microcosm incubation, we measured CO2 emissions, soluble organic carbon (SOC), total inorganic N (TIN) and microbial biomass C (MBC). Our results showed that CO2, SOC, TIN and MBC differed significantly among litter treatments and soil moisture. In the litter mixture, frequent and unsystematic non-additive effects could be found in CO2, SOC, TIN and MBC, and the non-additivities could be explained by the litter chemical traits. Higher soil moisture strengthened the synergistic effects of litter-mixing on CO2 and antagonistic effects on TIN, while weaken the synergistic effect on SOC and the antagonistic effects on MBC. This result indicated that, under multiple litter species decomposition, a changing soil moisture from dry to wet generally accelerate CO2 emission and increase MBC, while decrease the accumulation of SOC and TIN. Our work demonstrated that soil C and N dynamics and their non-additive responses to litter mixture were climatic context dependent. Soil moisture condition should be considered in understanding the effects of litter diversity on soil C and N processes.

24723. 题目: A fluorescence-based assessment of the fate of organic matter in water treated using crude/purified Hibiscus seeds as coagulant in drinking water treatment
文章编号: N18072203
期刊: Science of The Total Environment
作者: Alfred Ndahi Jones, John Bridgeman
更新时间: 2018-07-22
摘要: This study used fluorescence excitation-emission matrices (EEMs) analysis to investigate the characteristics of natural organic matter (NOM) in treated water using okra crude extract (OCE), sabdariffa crude extract (SCE) and kenaf crude extract (KCE) as coagulants. In addition, an assessment of the impact of purified okra protein (POP), purified sabdariffa protein (PSP) and purified kenaf protein (PKP) was undertaken. The performance evaluation of these coagulants in terms of increase or decrease in dissolved organic carbon (DOC) was compared with Peak T fluorescence intensity observed at excitation wavelength 220–230 nm, and emission wavelength 340–360 nm. Fluorescence analysis of water treated with the crude extracts identified the removal of DOC in peaks A and C region whereas the increase in DOC from the protein was predominantly found in peaks T and B region. Furthermore, it was observed that the purified proteins were noted to be capable of reducing the DOC concentration in raw water where all fluorophores were not detected. The application of OCE, SCE and KCE yielded an increase in DOC of 65, 61 and 55% respectively, corresponding to increases of 65, 29 and 54% in peak T fluorescence intensities, at 100 mg/l dose. Furthermore, DOC concentration was reduced by 25, 24 and 18% using POP, PSP and PKP respectively as coagulants with corresponding decreases in fluorescence intensity of 46%, 44 and 36% in POP, PSP and PKP, at a lower dose of 0.1 mg/l. Therefore, it is clear that Peak T fluorescence intensity could be used to characterise organic matter in treated water using natural extracts to assess final water quality.
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24724. 题目: Application potential of biochar in environment: Insight from degradation of biochar-derived DOM and complexation of DOM with heavy metals
文章编号: N18072202
期刊: Science of The Total Environment
作者: Mei Huang, Zhongwu Li, Ninglin Luo, Ren Yang, Jiajun Wen, Bin Huang, Guangming Zeng
更新时间: 2018-07-22
摘要: Biochar-derived dissolved organic matter (DOM) is important for determining the application potential of biochar in soil remediation. However, little is known about the degradation behavior of biochar-derived DOM and its interaction with heavy metals. Here, incubation experiments combined with quenching titration experiments, which analyzed by spectroscopic technology and chemometric method, were conducted to reveal such behaviors and mechanisms. Ultraviolet–visible (UV–Vis) spectra showed that high aromatic and hydrophobic fractions were enriched in biochar-derived DOM and enhanced during the cultivation process, thus the biochar-derived DOM may retain a high aromaticity, stability, and resistance. However, the environmental risk of Cu caused by the increase of DOM hydrophobicity cannot be overlooked while applying biochar to polluted soil. One fulvic-like (C1), one protein-like (C2) and two humic-like (C3, C4) substances were identified from biochar-derived DOM by using parallel factor analysis of excitation-emission matrix. Additionally, the fluorescence intensity variations of these components in DOM offered an additional interpretation for the observations from UV–Vis spectra. Two-dimensional correlation spectroscopy revealed that Cd binding to biochar-derived DOM first occurred in the protein- and fulvic-like fraction while protein- and humic-like substances had a stronger affinity for Cu. Furthermore, both phenolic and carboxyl groups firstly participated in the binding process of Cd with biochar-derived DOM, while polysaccharide gave the fastest response to Cu binding. These results clearly demonstrated the differences in specific heavy metal binding features of individual fluorescent substances and functional groups in biochar-derived DOM and contribute to improving the application effect of biochar in a multi-heavy metal polluted soil system.
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24725. 题目: Using biochar capping to reduce nitrogen release from sediments in eutrophic lakes
文章编号: N18072201
期刊: Science of The Total Environment
作者: Yaoyao Zhu, Wenzhong Tang, Xin Jin, Baoqing Shan
更新时间: 2018-07-22
摘要: The effects of reduced nitrogen release from sediments were studied using biochar (BC) capping in simulated water–sediment systems. Dried solid waste of Phyllostachys pubescens was used to produce BC, which was then pyrolyzed at 500 °C. Subsequently, 14 sediment cores were collected, including the sediment–water interface and some overlying water, from two sites in Baiyangdian Lake (China). The sediment cores were split into two batches (A and B), and then two each were capped with soil, BC or a BC/soil mixture, and incubated for 30 days. In the BC capped cores, the ammonia nitrogen (NH4+-N), nitrate nitrogen (NO3 -N) and total nitrogen (TN) concentrations decreased from 0.90 mg·L 1 to 0.05 mg·L-1, 0.88 mg·L-1 to 0.18 mg·L-1, 6.93 mg·L-1 to 2.81 mg·L-1, respectively, in batch A and 3.51 mg·L-1 to 0.11 mg·L-1, 0.92 mg·L-1 to 0.61 mg·L-1, 8.88 mg·L-1 to 3.32 mg·L-1, respectively, in batch B. The sediments to water fluxes of NH4+-N, NO3--N and TN were greatly reduced or reversed. Compared with other cappings, the BC layer was shown to absorb more NH4+-N from the pore water, thereby breaking the diffusion gradient of NH4+-N at the sediment–water interface, and has a good inhibitory effect on the endogenous release of NH4+-N from the sediments. Additionally, in the BC capped cores, the redox potential remarkably increased and dissolved oxygen was comparatively high. This study suggests that BC capping can reduce the amount of nitrogen released from polluted sediments because the diffusion of nitrogen to the overlying water is chemically blocked by the cap.
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24726. 题目: Estimating sedimentary organic matter sources by multi-combined proxies for spatial heterogeneity in a large and shallow eutrophic lake
文章编号: N18072129
期刊: Journal of Environmental Management
作者: Zhichun Li, Xiaoguang Xu, Ming Ji, Guoxiang Wang, Ruiming Han, Jie Ma, Xingcheng Yan, Jine Liu
更新时间: 2018-07-21
摘要: The multiple proxies involving elemental and stable isotope ratios (C/N, δ15N and δ13C) and biomarkers are powerful tools for estimating sedimentary organic matter (SOM) sources. However, the systematic and reasonable evaluation of organic matter sources existing with serious spatial heterogeneity in large, shallow and eutrophic lakes is still far from clear. Samples of sediments, aquatic plants and particulate organic matter (POM) collected from different ecotype regions of Taihu Lake, China, including algae-type lakeshore, grass-type lakeshore, algae-grass-type lakeshore, inflow rivers and estuary, groove reed zone, offshore and central regions, were analyzed for their SOM sources via elemental and stable isotope ratios (C/N, δ15N and δ13C), n-alkanes and fatty acids (FA). More depleted δ13CTOC values ( 26.3‰ to 25.4‰) and higher relative percentages of odd n-alkanes (C26 to C35) and long-chain FA (C24:0 to C32:0) clarified the influence of inflow rivers carrying terrestrial inputs on SOM. The higher relative percentages of n-alkanes from C14 to C20, FA (C16:0), and polyunsaturated FA (C18:2 and C18:3) in the reed belt of the groove demonstrated that some special terrain was important for the accumulation of algae-derived OM in sediments. Short-chain and middle-chain biomarker compounds revealed a large contribution from macrophytes in the grass-type region and an obvious algae-derived organic matter accumulation in the algae-type region, respectively. However, some overlapping ranges of C/N, δ15N and δ13C among aquatic plants, the ubiquity of lipid biomarkers compounds, anthropogenic influences, meteorological factors and lake topography caused some biased identification results for partial samples using different indicators. These biased identifications were mainly embodied in the source category and contribution difference based on principal component analysis and an end-member mixing model. Therefore, the estimation of SOM sources by multiple proxies cannot be uniformly applied in large freshwater lakes. The systematic investigation and comprehensive understanding of the different ecotypes and their surrounding environments are the important links in the identification of SOM sources via multiple indicators.
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24727. 题目: Organic nitrogen addition suppresses fungal richness and alters community composition in temperate forest soils
文章编号: N18072128
期刊: Soil Biology and Biochemistry
作者: Lauren C. Cline, Julia A. Huggins, Sarah E. Hobbie, Peter G. Kennedy
更新时间: 2018-07-21
摘要: Human-driven increases in bioavailable nitrogen over the last century have revealed the critical need to understand how nitrogen availability influences terrestrial ecosystems. In contrast to widespread evidence that increasing inorganic nitrogen strongly influences the diversity and composition of plant and microbial communities, the effect of organic nitrogen addition, the predominant form of nitrogen in soils, remains less clear. In this study, we conducted a field experiment manipulating both the amount and composition of soil organic nitrogen present in soil fungal in-growth bags, followed by molecular characterization of fungal communities after a four-month incubation. Saprotrophic and ectomycorrhizal fungi readily colonized experimental in-growth bags, indicating a broad overlap in the fundamental niches of these two functional guilds. Increases in labile forms of organic nitrogen resulted in sharp declines in species richness and diversity across fungal guilds, as well as notable shifts in fungal community composition. The relative abundance of fungi classified as molds and yeasts peaked where organic nitrogen was both high and most labile, whereas slower-growing saprotrophic and ectomycorrhizal fungi were more abundant in the non-amended treatments. Taken together, our results indicate that similar to inorganic nitrogen, increasing the amount of organic nitrogen can dramatically alter the richness and composition of fungal communities in temperate forest soils.

24728. 题目: Novel insights into heavy metal pollution of farmland based on reactive heavy metals (RHMs): pollution characteristics, predictive models, and quantitative source apportionment
文章编号: N18072127
期刊: Journal of Hazardous Materials
作者: Lixun Zhang, Guangyu Zhu, Xin Ge, Gang Xu, Yuntao Guan
更新时间: 2018-07-21
摘要: Recently, soil contamination by heavy metals in farmland has become a severe problem. In this study, a novel assessment method of heavy metal pollution based on reactive heavy metals (RHMs) was introduced. RHMs showed strong correlation with soil profile and land use, distinctly different from the variation of total heavy metals. According to modified geoaccumulation and Hakanson index, farmlands in study area were certainly polluted by various heavy metals, but had low ecological risk. RHMs were greatly influenced by soil properties such as nitrogen, phosphorus, organic matter (OM), pH, moisture content, cation exchange capacity (CEC), electrical conductivity, inorganic anion, and soil texture. Freundlich-type empirical models were developed by combining pH, OM, CEC, total phosphorus, and clay for sufficiently robust and accurate prediction of RHM contents in farmland. The absolute principal component score with multiple linear regression (APCS-MLR) model was used to quantify sources of RHMs in farmland. Agricultural production (water-fertilizer management practice and fertilizer/pesticide use) was the major influence on RHMs with contributions greater than 50% for Fe, Cu, Zn, Pb, and As. Industrial activity, traffic emission, and soil erosion should be also given special attentions because of their great influence on soil RHM contents.
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24729. 题目: Intensity and frequency of nitrogen addition alter soil chemical properties depending on mowing management in a temperate steppe
文章编号: N18072126
期刊: Journal of Environmental Management
作者: Ruzhen Wang, Yunhai Zhang, Peng He, Jinfei Yin, Junjie Yang, Heyong Liu, Jiangping Cai, Zhan Shi, Xue Feng, Feike A. Dijkstra, Xingguo Han, Yong Jiang
更新时间: 2018-07-21
摘要: Anthropogenic nitrogen (N) enrichment can significantly alter soil chemical properties in various ecosystems. Previous manipulative N experiments mainly focused on the intensity of N addition on soil properties by changing N input rates. It remains unclear, however, whether frequency of N addition can affect soil chemical properties. We examined the effects of frequency (2 versus 12 applications yr-1) and rate (ranging from 0 to 50 g N m-2 yr-1) of N addition on soil chemical properties of pH, base cations, soil pH buffering capacity (pHBC), and soil available micronutrients in a temperate steppe with and without mowing. Mowing significantly increased the effective cation exchange capacity (ECEC), soil exchangeable Ca and Na, available Fe, and soil pHBC when N was applied at low frequency. Low frequency of N addition significantly decreased soil pH and exchangeable Na but increased soil exchangeable Mg without mowing; however, it increased soil exchangeable Na and available Zn with mowing, while available Fe and Mn increased both with and without mowing. Higher rates of N addition (≥20 g N m-2 yr-1) decreased soil pH, ECEC and exchangeable Ca but increased soil available Fe, Mn and Cu regardless of the mowing treatment and frequency of N addition. Changes in soil organic matter, pHBC and ECEC were the main reasons affecting soil pH across mowing and N application treatments. Our results indicate that frequency of N addition played an essential role in altering soil chemical properties. Simulating N deposition via large and infrequent N additions can underestimate (exchangeable Mg and available Fe and Mn) or overestimate (soil pH and exchangeable Na) changes in soil properties. Our results further suggest that the effects of frequency of N addition on soil chemical attributes in semi-arid grassland ecosystems can be regulated by appropriate mowing management.
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24730. 题目: Influence of chain length of long-chain fatty acid surfactant on the thermal conductivity of magnetite nanofluids in a magnetic field
文章编号: N18072125
期刊: Colloids and Surfaces A: Physicochemical and Engineering Aspects
作者: Arun Dadwal, P.A. Joy
更新时间: 2018-07-21
摘要: Stable magnetic nanofluids are prepared by dispersing long-chain fatty acid surfactants coated magnetite (Fe3O4) nanoparticles in toluene and investigated the effect of chain length of the surfactant molecules on the thermal conductivity of the magnetite nanofluids in a magnetic field. Superparamagnetic magnetite nanoparticles having a comparable particle size (~10 nm) are coated with three different long-chain fatty acid surfactants; myristic acid (C13H27COOH), palmitic acid (C15H31COOH) and stearic acid (C17H35COOH). The thermal conductivity of the nanofluids, in a magnetic field, is found to decrease with increasing the chain length of the surfactant molecule. Among the three fluids, the shorter chain myristic acid coated nanofluid showed larger enhancement in the thermal conductivity at smaller fields as compared to the other fluids. The results indicated that the chain length of the surfactant molecule present on the surface of the magnetite nanoparticles affect the thermal conductivity of the magnetic nanofluid in an external magnetic field, due to the difference in the extent of interdigitation of the surfactant molecules.
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24731. 题目: Fabrication of GO modified PVDF membrane for dissolved organic matter removal: removal mechanism and antifouling property
文章编号: N18072124
期刊: Separation and Purification Technology
作者: Jingjing Zhao, Yu Yang, Chen Li, Li-an Hou
更新时间: 2018-07-21
摘要: In this study, graphene oxide (GO) layers were successfully grafted onto a polyvinylidene fluoride (PVDF) membrane using chemical activated treatment and layer-by-layer assembly method. The physicochemical properties of GO modified membranes were analyzed by Fourier-transform infrared spectroscopy, field-emission scanning electron microscopy, zeta potential, and water contact angle measurements. Our results showed that GO layers resulted in a decrease in pore size, an increase in the negative surface charge and hydrophilicity of the modified membrane. Thus, much higher removal rates of proteins, humic acids and fulvic acids were observed for GO modified membranes due to the enhanced size exclusion. Notably, the higher rejection of the smaller molecular weight (MW) organics in the range of 50-500 Da was also obtained for the GO modified membrane, which was attributed to the size exclusion of GO layers’ surface and adsorption effect of GO layers. The foulant desorbed from fouled membrane before and after physical rinsing illustrated that, the hydrophilic and proteins with large MW were the major foulants resulting in irreversible fouling for both pristine and GO modified membranes. The pristine membrane exhibited severe irreversible fouling caused by pore blocking. However, GO modified membrane displayed the efficient antifouling performance. The foulants were more prone to forming a loose cake layer on the surface and prevented membrane pore blocking due to the negative charge and stronger hydrophilicity of GO layers, which resulted in a lower irreversible fouling ratio during the filtration of DOM solution. Therefore, GO modified membranes exhibited the higher rejections of foulants with large MW and small MW and better antifouling property in comparison of pristine membrane.

24732. 题目: Changes in the distribution of Uvigerinidae species over the past 775?kyr: Implications for the paleoceanographic evolution of the Japan Sea
文章编号: N18072123
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Manisha Das, Raj K. Singh, Nishant Vats, Ann Holbourn, S. Mishra, S.H. Farooq, D.K. Pandey
更新时间: 2018-07-21
摘要: The distribution of benthic foraminifera of the Uvigerinidae family, which are abundant in middle to upper Pleistocene samples from the Yamoto Basin in the Japan Sea, have been analyzed quantitatively and used for paleoceanographic interpretations. Twenty-three Uvigerinidae species are reported from IODP Site U1426, 6 of which are present in at least three or more samples with 10% or more abundance and considered as dominant species. The abundance and ecological preferences of dominant Uvigerinidae species, comprised of Uvigerina mediterranea, Uvigerina yabei, Uvigerina sp.1, Uvigerina peregrina suggest dysoxic conditions, with high influx of organic matter between 775 and 475 ka in response to the enhanced flow of the Tsushima Warm Current. The end of MIS 13 marked the onset of more extreme glacial interglacial climate cycles in the Japan Sea. Glacial interglacial alternations of Uvigerina peregrina and Trifarina angulosa from 475 ka to the Holocene indicate major fluctuations in circulation and productivity within this semi-enclosed basin. Both U. peregrina and T. angulosa respond to 100 kyr variability, reflecting the paleoclimatic shift and global ice volume changes associated with the Middle Pleistocene Transition.

24733. 题目: Effect of bioflocculants on the coagulation activity of alum for removal of trihalomethane precursors from low turbid water
文章编号: N18072122
期刊: Journal of Environmental Sciences
作者: Tanwi Priya, Abhrajyoti Tarafdar, Bramha Gupta, Brijesh Kumar Mishra
更新时间: 2018-07-21
摘要: Reactivity of chlorine towards hydrophobic groups present in natural organic matter (NOM) provokes the formation of carcinogenic disinfection byproducts such as trihalomethanes in chlorinated water. The present study aimed to investigate the variations in coagulant activity of alum using two different bioflocculants (coagulant aid) namely, Moringa oleifera and Cyamopsistetragonoloba for the removal of hydrophobic fractions of NOM and subsequent chlorine consumption by treated water. Effect of dual coagulants on trihalomethane surrogate parameters such as total organic carbon, dissolved organic carbon, UV absorbing materials and prominent hydrophobic species such as phenolic groups along with aromatic chromophores, polyhydroxy aromatic moiety have also been studied. The concept of differential spectroscopy and absorbance slope index has been employed to understand the combined effects of alum-bioflocculants on the reactivity of NOM with chlorine. Our result shows that the combination of alum and C. tetragonoloba is more efficient for reducing trihalomethane surrogates from chlorinated water as compared to M. oleifera. C. tetragonoloba elicited synchronized effects of sweep coagulation and particle bridging-adsorption which eventually facilitated efficient removal of hydrophobic fractions of NOM. The variation in the mechanistic approach of bioflocculants was due to the presence of cationic charge on M. oleifera and adhesive property of C. tetragonoloba.
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24734. 题目: Relating Cd2 + binding by humic acids to molecular weight: A modeling and spectroscopic study
文章编号: N18072121
期刊: Journal of Environmental Sciences
作者: Hongcheng Bai, Zhenmao Jiang, Minjin He, Biying Ye, Shiqiang Wei
更新时间: 2018-07-21
摘要: Molecular weight (Mw) is a fundamental property of humic acids (HAs), which considerably affect the mobility and speciation of heavy metals in the environment. In this study, soil humic acid (HA) extracted from Jinyun Mountain, Chongqing was ultra-filtered into four fractions according to the molecular weight, and their properties were characterized. Complexation of cadmium was investigated by titration experiments. For the first time, Langmuir and non-ideal competitive adsorption-Donna (NICA-Donnan) models combined with fluorescence excitation-emission matrix (EEM) quenching were employed to elucidate the binding characteristics of individual Mw fractions of HA. The results showed that the concentration of acidic functional groups decreased with increasing Mw, especially the phenolic groups. The humification degree and aliphaticity increased with increasing Mw as indicated by elemental composition analysis and FT-IR spectra. The binding capacity of Cd2 + to Mw fractions of HA followed the order UF1 (< 5 kDa) > UF2 (5–10 kDa) > UF4 (> 30 kDa) > UF3 (10–30 kDa). Moreover, the distribution of cadmium speciation indicated that the phenolic groups were responsible for the variations in binding of Cd2 + among different Mw fractions. The results of fluorescence quenching illustrated that the binding capacity of Cd2 + to Mw fractions was controlled by the content of functional groups, while the binding affinity was largely influenced by structural factors. The results provide a better understanding of the roles that different HA Mw fractions play in heavy metal binding, which has important implications in the control of heavy metal migration and bio-toxicity.
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24735. 题目: Spectroscopic study on transformations of dissolved organic matter in coal-to-liquids wastewater under integrated chemical oxidation and biological treatment process
文章编号: N18072120
期刊: Journal of Environmental Sciences
作者: Siwei Peng, Xuwen He, Hongwei Pan
更新时间: 2018-07-21
摘要: A large amount of wastewater containing various toxic organic contaminants is produced during coal-to-liquids process. In this study, several spectroscopic methods were used to monitor the transformation of organic pollutants during an integrated chemical oxidation and biological process. The results showed that the hydrophobic acid fraction increased after Fenton oxidation, which was likely due to the production of small-molecule organic acids. Soluble microbial products were generated during biological treatment processes, which were degraded after ozonation; meanwhile, the hydrophilic base and acid components increased. Ultraviolet-visible spectroscopic analysis indicated that peaks at the absorption wavelengths of 280 and 254 nm, which are associated with aromatic substances, were detected in the raw water. The aromatic substances were gradually removed, becoming undetectable after biological aeration filter (BAF) treatment. Fourier transform infrared spectroscopy analysis revealed that the functional groups of phenols; benzene, toluene, ethylbenzene, and xylene (BTEX); aromatic hydrocarbons; aliphatic acids; aldehydes; and esters were present in raw wastewater. The organic substances were oxidized into small molecules after Fenton treatment. Aromatic hydrocarbons were effectively removed through bioadsorption and biodegradation after BAF process. Biodegradable organic matter was reduced and finally became undetectable after anoxic–oxic treatment in combination with a membrane bioreactor. Four fluorescent components were fractionated and obtained via excitation–emission matrix parallel factor analysis (EEM-PARAFAC). Dissolved organic matter fractionation in conjunction with EEM-PARAFAC was able to monitor more precisely the evolution of characteristic organic contaminants.
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24736. 题目: Influence of sodium dodecyl sulfate coating on adsorption of methylene blue by biochar from aqueous solution
文章编号: N18072119
期刊: Journal of Environmental Sciences
作者: Wei Que, Luhua Jiang, Chen Wang, Yunguo Liu, Zhiwei Zeng, Xiaohua Wang, Qimeng Ning, Shaoheng Liu, Peng Zhang, Shaobo Liu
更新时间: 2018-07-21
摘要: Biochar is regarded as a promising new class of materials due to its multifunctional character and the possibility of effectively coupling different properties. With increasing introduction into the environment, environmental chemicals such as surfactants will load onto the released biochar and change its physicochemical characteristics and adsorption behavior toward pollutants. In this study, sodium dodecyl sulfate (SDS), as one type of anionic surfactant, was coated onto biochar with different loading amounts. The influence of SDS loading onto biochar's physicochemical properties were investigated by Fourier transform infrared (FT-IR) spectroscopy, elemental analysis, zeta potential and Brunauer–Emmett–Teller (BET) surface area and pore size distribution analysis. Results showed that the pore size of the biochar decreased gradually with the increase of SDS loading because of the surface-adsorption and pore-blocking processes; the pH of the point of zero charge (pHPZC) decreased with increasing SDS loading. Although surface-coating with SDS decreased the pore size of the biochar, its adsorption capacity toward Methylene Blue (MB) significantly increased. The biochar-bound SDS introduced functional groups and negative charges to the biochar surface, which could thus enhance the adsorption of MB via hydrogen bonding and electrostatic interaction. The results can shed light on the underlying mechanism of the influence of anionic surfactants on the adsorption of MB by biochar.
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24737. 题目: Sediment granulometry and salinity drive spatial and seasonal variability of an estuarine demersal fish assemblage dominated by juvenile fish
文章编号: N18072118
期刊: Estuarine, Coastal and Shelf Science
作者: Yureidy Cabrera Páez, Consuelo María Aguilar-Betancourt, Gaspar González-Sansón, Fátima Negrete Rodríguez, Michelle Gray
更新时间: 2018-07-21
摘要: Abiotic factors are known to structure estuarine fish communities; however, their effects on the ichthyofauna are not yet clear. The objective of this study was to evaluate abundance and composition, by species and size, of the demersal ichthyofauna in a Mexican Central Pacific lagoon, and correlate its spatial and seasonal variations with selected abiotic factors. Eight sampling campaigns were conducted in representative months of the dry and rainy seasons between April 2015 and February 2017. Salinity, temperature and sediment granulometry were recorded. A total of 10 093 individuals of 64 species were collected and measured for total length. Of the 22 most abundant species, 19 were mainly juveniles (>50%). Diapterus brevirostris, Achirus mazatlanus, Centropomus robalito and Lutjanus argentiventris comprised more than 80% of the total collection. PERMANOVA yielded significant differences in fish community composition between sites and months, and post hoc tests resulted in four homogenous, significantly different groups of sites based on fish assemblage composition. These groups of sites lie well ordered along a west-east axis inside the lagoon. Two well separated seasonal groups of months were defined, namely dry season (February, April) and rainy season (July, October). The spatial changes in abundance and composition of the fish fauna were primarily explained by the Site factor in a spatial scale, while the Month factor influenced to a lesser degree the community structure on a seasonal scale. Redundancy analysis showed the type of sediment, the bottom salinity and the organic matter content were highly correlated with the composition and abundance of ichthyofauna in the lagoon. One species group (dominated by D. brevirostris, C. robalito and A. mazatlanus) was found to be highly positively correlated with percentage of mud and organic matter but negatively correlated with bottom salinity. Another species group (dominated by Diodon holocanthus, Eucinostomus dowii, Sphoeroides annulatus and Chaetodon humeralis) was highly correlated with percentage of sand and bottom salinity. A high number of juveniles in the catches also validates the Barra de Navidad lagoon as a probable nursery area.

24738. 题目: Optical properties of straw-derived dissolved organic matter and growth inhibition of Microcystis aeruginosa by straw-derived dissolved organic matter via photo-generated hydrogen peroxide
文章编号: N18072117
期刊: Environmental Pollution
作者: Hua Ma, Liping Huang, Jie Zhang, Dezhi Shi, Jixiang Yang
更新时间: 2018-07-21
摘要: Recent advances in research on algae inhibition by using low-cost straw proposed a possible mechanism that reactive oxygen species (ROS) generated by the solar irradiation of straw-derived dissolved organic matter (DOM) might contribute to cyanobacteria inhibition. However, this process is not clearly understood. Here, DOM from three types of straw (barley, rice, and wheat) and natural organic matter (NOM) isolates were investigated in terms of their photochemical properties and ROS generating abilities. Results demonstrated that the DOM derived from the aeration decomposition of barley straw (A-DOMbs) yielded the best formation efficiencies of hydrogen peroxide (H2O2) and hydroxyl radicals ( OH) under solar-simulated irradiation in all organic matter samples. Correlation analysis implies that optical parameters and phenolic hydroxyl group contents can signify ROS generating abilities of different DOM solutions. Bioassay results show that A-DOMbs possesses the highest inhibition performance for M. aeruginosa in all DOM samples, much higher than those of NOM isolates. The addition of catalase greatly relieves the inhibition performance, making the loss of chlorophyll a content decreased from 37.14% to 7.83% in 2 h for A-DOMbs, which implies that for cyanobacteria growth inhibition, photochemically-produced H2O2 from SOM is far more important than singlet oxygen (1O2),· OH, and even SOM itself. Our results show that H2O2 photochemically generated from straw-derived DOM is able to result in rapid inhibition of M. aeruginosa in a relatively short period, furthering the understanding of complicated mechanisms of cyanobacteria inhibition by using low-cost straw in eutrophic waters.
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24739. 题目: Unraveling microbial turnover and non-extractable residues of bromoxynil in soil microcosms with 13C-isotope probing
文章编号: N18072116
期刊: Environmental Pollution
作者: Karolina M. Nowak, Markus Telscher, Erika Seidel, Anja Miltner
更新时间: 2018-07-21
摘要: Bromoxynil is a widely used nitrile herbicide applied to maize and other cereals in many countries. To date, still little is known about bromoxynil turnover and the structural identity of bromoxynil non-extractable residues (NER) which are reported to occur in high amounts. Therefore, we investigated the microbial turnover of 13C-labeled bromoxynil for 32 days. A focus was laid on the estimation of biogenic NER based on the turnover of 13C into amino acids (AA). At the end, 25% of 13C6-bromoxynil equivalents were mineralized, 2% assigned to extractable residues and 72.5% to NER. Based on 12% in the 13C-total AA and an assumed share of AA of 50% in microbial biomass we arrived at 24% of total 13C-biogenic NER. About 33% of the total 13C-NER could thus be explained by 13C-biogenic NER; 67% was unknown and by definition xenobiotic NER with potential for toxicity. The 13C label from 13C6-bromoxynil was mainly detected in the humic acids (28.5%), but significant amounts were also found in non-humics (17.6%), fulvic acids (13.2%) and humins (12.7%). The 13C-total amino acids hydrolyzed from humic acids, humins and fulvic acids amounted to 5.2%, 6.1% and 1.2% of 13C6-bromoxynil equivalents, respectively, corresponding to total 13C-biogenic NER amounts of 10.4%, 12.2% and 2.4%. The humins contained mostly 13C-biogenic NER, whereas the humic and fulvic acids may be dominated by the xenobiotic NER. Due to the high proportion of unknown 13C-NER and particularly in the humic and fulvic acids, future studies should focus on the detailed characterization of these fractions.
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24740. 题目: Comparison of organic matter removals in single-component and bi-component systems using enhanced coagulation and magnetic ion exchange (MIEX) adsorption
文章编号: N18072115
期刊: Chemosphere
作者: Yingying Chen, Weiying Xu, Hongjian Zhu, Dong Wei, Ning Wang, Mengting Li
更新时间: 2018-07-21
摘要: Natural organic matter (NOM) in aquatic environments have a significant impact on NOM-organic compound interactions, which could strongly affect the distribution and transformation of organic compounds during water treatment. This study focused on the removals of NOM (humic acid, HA) and synthetic organic matter (ibuprofen, IBP) through enhanced coagulation and magnetic ion exchange (MIEX) resin adsorption in single and bi-component systems. Two coagulants, traditional aluminum sulfate (AS) and lab-prepared polyaluminum chloride (PACl), were employed. The charge properties, particle size distribution, and fractal dimension (Df) during organic matter removal were studied in both the single and bi-component systems to explore the purification behaviors and mechanistic effects of interactions between coagulants, MIEX, and organic matters. The experimental results indicated that the Al-based coagulants could remove over 80% of HA in both the single and IBP-HA combined systems, while the presence of HA could considerably improve the IBP removal rate. The aggregates formed during single-component coagulation were larger, but weaker and more loosely structured than those formed in the bi-component system under the same coagulation conditions. In the single-component system, the maximum removal efficiencies of IBP and HA by MIEX adsorption were 65% and 72%, respectively, at a resin dosage of 20.0 mL/L and mixing time of 60 min. Under the same conditions, the removals of these components in the bi-component system were improved to 68% and 98%, respectively. The reaction rate between IBP and MIEX resin was found faster than that between HA and MIEX resin.
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