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28121. 题目: Removal of natural organic matter and disinfection byproduct precursors from drinking water using photocatalytically regenerable nanoscale adsorbents
文章编号: N18111806
期刊: Chemosphere
作者: Stephanie L. Gora, Susan A. Andrews
更新时间: 2018-11-18
摘要: Disinfection byproduct precursors (DBPs) were removed from raw surface water obtained from two Canadian drinking water treatment plants via adsorption to two regenerable linear engineered TiO₂ nanomaterials (LENs). The temperature employed in the final heating step of the LEN synthesis procedure was varied to produce two distinct nanomaterials, NB 550 and NB 700. The LENs had similar dimensions but differed in terms of surface characteristics, surface area, and crystal structure. Unlike the commercial TiO₂ nanoparticles, both LENs were easily removed from the treated water via settling or filtration. Although neither of the LENs were as effective for NOM adsorption as commercial nanoparticles, both were able to remove substantial amounts of DBP precursors. NB 550 reduced the trihalomethane (THM) formation potential of both water sources by up to 40% and their haloacetic acid (HAA) formation potential by approximately 50%. NB 700 reduced the THM formation potential of one water source by 25% and that of the other by 40%. HAA precursor removal by NB 700 ranged from 25% to 30%. The adsorption of DOC, UV254, THM precursors, and HAA precursors by commercial nanoparticles and the LENs fit a modified Freundlich adsorption isotherm model. When the LENs were regenerated via exposure to UVA light they experienced a gradual loss in adsorption capacity of up to 50% over five regeneration cycles. This loss occurred more quickly for the less photoactive of the two nanomaterials, and was affected by water source, suggesting that components of the water matrices may have interfered with regeneration.
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28122. 题目: Co-transport of graphene oxide and heavy metal ions in surface-modified porous media
文章编号: N18111805
期刊: Chemosphere
作者: Xianqiang Yin, Yanji Jiang, Yuehui Tan, Xiangmin Meng, Huimin Sun, Nong Wang
更新时间: 2018-11-18
摘要: The ability to predict the transport of heavy metal ions in porous media with different surface characteristics is crucial to protect groundwater quality and public health. In this study, the effects of graphene oxide (GO) on co-transport and remobilization of Pb²⁺ and Cd²⁺ in humic acid (HA), smectite, kaolinite, and ferrihydrite-coated sand media were evaluated via laboratory packed-column experiments. Scanning electron microscope and energy dispersive X-ray analysis showed that the surface morphology of the coated sands was quite different and that ∼56.7–89.9% of the surface was covered by the coating and the major elemental components were C, O, Si, Al, and Fe. GO exhibited high mobility in HA, kaolinite, and smectite-coated sand, but showed high retention in ferrihydrite-coated sand. While GO reduced the transport of Pb²⁺ and Cd²⁺, both metal ions also reduced the mobility of GO in coated-sand columns. Elution experiments revealed that GO led to the remobilization and release of the previously sorbed Pb²⁺ and Cd²⁺ from the coated sand. However, GO could not release Pb²⁺ and Cd²⁺ from smectite-coated sand columns, probably because smectite has stronger adsorption affinity to the heavy metals than GO. Derjaguin-Landau-Verwey-Overbeek calculations were employed and explained the GO transport behavior in the columns well. Furthermore, the advection-dispersion-reaction equation simulated the cotransport of Pb²⁺ and Cd²⁺ with GO in the coated sand well. These results are expected to provide insight into the potential impact of coexisting nanomaterials with contaminants in vulnerable soil and groundwater systems.
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28123. 题目: The collaborative effect of Chlorella vulgaris-Bacillus licheniformis consortia on the treatment of municipal water
文章编号: N18111804
期刊: Journal of Hazardous Materials
作者: Xiyan Ji, Huimin Li, Jibiao Zhang, Hexige Saiyin, Zheng Zheng
更新时间: 2018-11-18
摘要: In this study, the effects of nutrient and dissolved organic matter removal, stress resistance (DNA methylation), and the algae-bacteria dynamic ratio of algal-bacterial consortia in actual municipal wastewater were investigated. Results indicate that the presence of a Chlorella vulgaris-Bacillus licheniformis consortium had profound effects. The removal rates of total nitrogen, ammonium, orthophosphate phosphorus and chemical oxygen demand were 88.82%, 84.98%, 84.87% and 82.25%, respectively. Protein-like substances, which are difficult to degrade in the natural water environment, were significantly degraded in actual municipal wastewater. Furthermore, the microbial diversity was measured. The algal-bacterial consortium did not disrupt the microbial in-situ diversity of the actual municipal wastewater under suitable conditions. The global nuclear DNA methylation level peaked at 7.80%. These results help to understand the effects of algal-bacterial consortia on nutrient and pollutant removal and adaptability in actual municipal wastewater.
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28124. 题目: Effective removal of inorganic mercury and methylmercury from aqueous solution using novel thiol-functionalized graphene oxide/Fe-Mn composite
文章编号: N18111803
期刊: Journal of Hazardous Materials
作者: Yao Huang, Yanyan Gong, Jingchun Tang, Siyu Xia
更新时间: 2018-11-18
摘要: A novel thiol-functionalized graphene oxide/Fe-Mn (SGO/Fe-Mn) was investigated for aqueous Hg²⁺ and CH₃Hg⁺ removal. Mercury were removed mainly through ligand exchange and complexation with surface active sites (i.e., −SH, −OH, O–C=O, C=C, Si−O, and π-π bond). −SH had the strongest binding ability with mercury, forming sulfur-containing organic matter or polymers with Hg²⁺, and sulfur-containing organometallic compounds or thiolate-like species with CH₃Hg⁺. The BET sorption isotherm model well simulated the sorption isotherm data of Hg²⁺ (R²=0.995, q_m=233.17 mg/g) and CH₃Hg⁺ (R²=0.997, q_m=36.69 mg/g), indicating a multilayer adsorption process. The mercury uptake was promoted with the increase of 3-MPTS content, adsorbent dosage, and pH (<5.5), whereas the uptake was inhibited by high pH (>5.5) and high concentrations of humic acid and electrolytes. SGO/Fe-Mn demonstrated high mercury uptake in simulated surface water/groundwater and in the presence of Pb, Cu, Ni, Sb, Cd and Zn. The mercury-laden SGO/Fe-Mn can be successfully regenerated and reused for three times with 98.1% and 67.0% of original Hg²⁺ and CH₃Hg⁺ sorption capacity when 5% thiourea + 2 M KI was used as the desorbing agent. This study demonstrates potential and viability of SGO/Fe-Mn for mercury remediation.
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28125. 题目: Depositional environment classification based on environmental variables of South Korea's Nakdong River Estuary barrier-lagoon system
文章编号: N18111802
期刊: Marine Pollution Bulletin
作者: Jae Ung Choi, Jeongwon Kang, Jun-Ho Lee, Han Jun Woo
更新时间: 2018-11-18
摘要: Anthropogenic activities have altered the geomorphological and ecological conditions of the Nakdong River Estuary (NRE) dramatically over the last century. The objectives of this study were to classify NRE sub-environments and to identify their unique ecological functions. The first step in classification was the establishment of 14 a priori sub-environmental groups based on landscape factors. Surface sediments obtained for these groups were analyzed for factors related to grain size and organic matter. Based on the results, the NRE was divided into two primary estuarine environment divisions: (1) a mixed marine and terrestrial environment influenced primarily by land; and (2) a principally marine environment influenced primarily by the ocean. Using multivariate analysis, we subdivided these primary estuarine divisions into six sub-environments, including Sub-1 and -2 in the former and Sub-3, -4, -5, and -6 in the latter.

28126. 题目: How to cope with NOB activity and pig manure inhibition in a partial nitritation-anammox process?
文章编号: N18111801
期刊: Separation and Purification Technology
作者: Andres Pichel, Reyes Moreno, Monica Figueroa, Jose Luis Campos, Ramon Mendez, Anuska Mosquera-Corral, Angeles Val del Rio
更新时间: 2018-11-18
摘要: The treatment of pig manure can be performed by anaerobic digestion to diminish the organic matter content and produce biogas, and the resulting digestate has to be subsequently treated for the removal of nitrogenous compounds. The partial nitritation-anammox (PN-AMX) process constitutes an interesting alternative. In the present study, three different short experiments were initially performed to study the influence of nitrite oxidizing bacteria (NOB) present in the inoculum and the pig manure composition over the start-up of the PN-AMX process. The presence of NOB in the inoculum showed to be more crucial than the available anammox activity for a good performance of the PN-AMX process. Batch activity experiments showed a reduction of at least 44.4% in the maximum specific anammox activity due to the pig manure, probably owed to its conductivity (between 6 and 8 mS/cm). In the subsequent long-term operation of the PN-AMX process with non-diluted pre-treated pig manure, the NOB were successfully limited for DO concentrations of 0.1 mg O₂/L, and a nitrogen removal rate (NRR) of 0.1 g N/(L·d) was achieved despite the presence of significant NOB activity in the start-up. A strict control of the DO concentration, with an optimal range of 0.07–0.10 mg O₂/L, was fundamental to balance the removal of nitrogen by PN-AMX and prevent NOB activity. The presence of organic matter, with a ratio sCOD/N in the influent between 0.18 and 1.14 g/g, did not hinder the PN-AMX process, and the contribution of heterotrophic denitrification to the removal of nitrogen was less than 10%.

28127. 题目: Biochar can increase nitrogen use efficiency of Malus hupehensis by modulating nitrate reduction of soil and root
文章编号: N18111715
期刊: Applied Soil Ecology
作者: Hui Cao, Liufang Ning, Mi Xun, Feng Feng, Ping Li, Songqing Yue, Jianfei Song, Weiwei Zhang, Hongqiang Yang
更新时间: 2018-11-17
摘要: A surplus of nitrogen (N) fertilizer can reduce plant nitrogen use efficiency (NUE), however, biochar can improve nutrient uptake by altering soil properties and root growth. Therefore, the objective was to determine how biochar alter soil nitrate (NO₃⁻-N) availability and root development, and then to affect the plant NUE. The biochar was prepared by heating the apple branches at 700 °C and low oxygen. The effects of biochar on NO₃⁻-N leaching and nitrogen oxides fluxes in orchard soil treated with five biochar rates (0, 0.5%, 1%, 2% and 4%) were investigated, the nitrate reduction in the soil and roots, and the NUE of Hupeh Crabapple (Malus hupehensis Rehd.) were measured in two soils amended (or not) with biochar, at six N fertilizer rates, using the solution culture, amino benzene sulfonate and subtraction method, respectively. The results showed that 0.5–4% (w/w) biochar decreased the leaching ratio of NO₃⁻-N (9.9–68.7%) and nitrogen oxides flux (6.3–19.2%) in the soil. Soil denitrification intensity were most significantly decreased in the presence of 1% biochar when N fertilizer was applied at 0–450 mg NO₃⁻-N kg⁻¹; the soil nitrate reductase (NR) activity decreased at the application of 0–50 mg NO₃⁻-N kg⁻¹ in the presence of biochar, The root NR activity and root activity of M. hupehensis were significantly increased in the presence of 1% biochar at the application of 0–300 mg NO₃⁻-N kg⁻¹. In the biochar-amended soil, when the highest root activity and NR activity were obtained, N fertilizer application rate were reduced by 33.3% and 66.7%, compared to the non-amended soil, respectively. The NUE of M. hupehensis was increased by biochar-amended from 6.77% to 261.53%, comparied with the non-amended soils. These results indicated that biochar amendment could decrease nitrate leaching and nitrate reduction in soil, and promote nitrate absorption and reduction by root, thereby increasing the biomass and NUE of M. hupehensis when the input of N fertilizer was reduced from 450 to 300 mg NO₃⁻-N kg⁻¹.

28128. 题目: Visible photodegradation of ibuprofen and 2,4-D in simulated waste water using sustainable metal free-hybrids based on carbon nitride and biochar
文章编号: N18111714
期刊: Journal of Environmental Management
作者: Amit Kumar, Gaurav Sharma, Mu. Naushad, Ala'a H. Al-Muhtaseb, Ajay Kumar, Indu Hira, Tansir Ahamad, Ayman A. Ghfar, Florian J. Stadler
更新时间: 2018-11-17
摘要: Rational designing of metal-free carbon nitride based photocatalysts can lead to an excellent optical response and a higher photocatalytic activity driven by visible and solar light. This combines green photocatalytic technology with greener materials prepared by facile approaches for environmental remediation. Herein we report utilization of star photocatalyst g-C₃N₄ (CN) to form highly efficient hetero-assemblies along with acidified g-C₃N₄ (ACN), polyaniline (PANI), reduced graphene oxide (RGO) and biochar. By use of these organic semiconductors we synthesize g-C₃N₄/ACN/RGO@Biochar (GARB), g-C₃N₄/PANI/RGO@Biochar (GPRB) and ACN/PANI/RGO@Biochar (APRB) nano-assemblies with different optical response and band edge positions for a better charge flow and reduced recombination of carriers. These synthesized catalysts were used for visible light powered degradation of 2,4-Dichlorophenoxy acetic acid (2,4-D) and ibuprofen (IBN). APRB performs the best and degrades 99.7% and 98.4% of 2,4-D and IBN (20 mg L⁻¹) under Xe lamp exposure in 50 min and retention of high activity in natural sunlight. Optical analysis, photoelectrochemical response and radical quenching studies show both hydroxyl and superoxide radical anions as major reactive species and a Z-scheme photocatalytic mechanism. RGO acts as an electron mediator and protects higher positioned bands of PANI and ACN in APRB for a remarkable photocatalytic activity for a metal free material. The degradation pathway was analyzed by LC-MS analysis and 42% and 40% total organic carbon was removed in 2 h for 2,4-D and IBN degradation respectively. The toxicity of degraded products was analyzed by analyzing viability of human peripheral blood cells with retaining of 99.1% cells.
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28129. 题目: Mulching-induced preservation of soil organic matter quality in a burnt eucalypt plantation in central Portugal
文章编号: N18111713
期刊: Journal of Environmental Management
作者: José M. De la Rosa, Nicasio T. Jiménez-Morillo, José A. González-Pérez, Gonzalo Almendros, Diana Vieira, Heike E. Knicker, Jakob Keizer
更新时间: 2018-11-17
摘要: Mulching has amply proven its effectiveness to mitigate post-fire soil erosion but its impacts on soil organic matter (SOM) quality and quantity continue poorly studied. The present study addressed this knowledge gap for a eucalypt plantation in central Portugal that had been burnt and, immediately after the wildfire, mulched with 13.6 Mg ha⁻¹ of eucalypt logging residues some five years before. This was done by performing a range of analytical techniques (elemental and isotope analyses, analytical pyrolysis and ¹³C NMR spectroscopy) not only on the bulk soil samples but also on their humic acids (HAs) and free organic matter (FOM) fractions. While mulching reduced soil and SOM losses with 91 and 93%, respectively, it also improved SOM quality of the topsoil, in particular in terms of HAs and FOM. At 0–4 cm depth, both HAs and FOM contents were roughly twice as high in the mulched plots as in the control plots. The effects of mulching on the molecular composition of HAs and FOM fractions, however, varied markedly. Analytical pyrolysis (Py-GC/MS) revealed that mulching had led to a noticeable accumulation of labile, aliphatic SOM constituents such as carbohydrate-derived and alkyl compounds (fatty acids and n-alkanes) but that it hardly affected the composition of HAs. Even so, solid-state ¹³C NMR spectroscopy showed that mulching had resulted in a relative increase in aryl C in the FOM fraction, suggesting an enhanced preservation of the pyrogenic OM. Overall, the combined use of a range of analytical techniques allowed to conclude that, five years after their application, the forest logging residues had led to a greater preservation of the fire-derived pyrogenic OM (mainly aromatic compounds) in the topsoil as well as to higher contents of SOM's most labile molecular constituents (mainly carbohydrates and n-alkyl compounds). The former reflected the reduced erosion rates, while the latter was probably due to a combination of reduced erosion rates with the additional input of fresh organic matter.

28130. 题目: Key role of bacteria in the short‐term cycling of carbon at the abyssal seafloor in a low particulate organic carbon flux region of the eastern Pacific Ocean
文章编号: N18111712
期刊: Limnology and Oceanography
作者: Andrew K. Sweetman, Craig R. Smith, Christine N. Shulse, Brianne Maillot, Markus Lindh, Matthew J. Church, Kirstin S. Meyer, Dick van Oevelen, Tanja Stratmann, Andrew J. Gooday
更新时间: 2018-11-17
摘要: The cycling of carbon (C) by benthic organisms is a key ecosystem function in the deep sea. Pulse‐chase experiments are designed to quantify this process, yet few studies have been carried out using abyssal (3500–6000 m) sediments and only a handful of studies have been undertaken in situ. We undertook eight in situ pulse‐chase experiments in three abyssal strata (4050–4200 m water depth) separated by tens to hundreds of kilometers in the eastern Clarion‐Clipperton Fracture Zone (CCFZ). These experiments demonstrated that benthic bacteria dominated the consumption of phytodetritus over short (~ 1.5 d) time scales, with metazoan macrofauna playing a minor role. These results contrast with the only other comparable in situ abyssal study, where macrofauna dominated phytodetritus assimilation over short (2.5 d) time scales in the eutrophic NE Atlantic. We also demonstrated that benthic bacteria were capable of converting dissolved inorganic C into biomass and showed that this process can occur at rates that are as high as the bacterial assimilation of algal‐derived organic C. This demonstrates the potential importance of inorganic C uptake to abyssal ecosystems in this region. It also alludes to the possibility that some of the C incorporation by bacteria in our algal‐addition studies may have resulted from the incorporation of labeled dissolved inorganic carbon initially respired by other unstudied organisms. Our findings reveal the key importance of benthic bacteria in the short‐term cycling of C in abyssal habitats in the eastern CCFZ and provide important information on benthic ecosystem functioning in an area targeted for commercial‐scale, deep‐sea mining activities.

28131. 题目: Carbon, nitrogen and phosphorus stocks differ among vegetation patch types in a degraded alpine steppe
文章编号: N18111711
期刊: Journal of Soils and Sediments
作者: Yan Yan, Linlin Tian, Ziyin Du, Scott X. Chang, Yanjiang Cai
更新时间: 2018-11-17
摘要: Purpose: Degradation of grassland creates diverse vegetation patch types with plant species with different palatabilities, potentially affecting ecosystem productivity and soil organic carbon (SOC) sequestration. This study investigated variations in SOC densities and carbon/nitrogen/phosphorus (C/N/P) ratios among vegetation patch types in a degraded alpine steppe on the Qinghai-Tibetan Plateau. Materials and methods: We examined soil, shoot and root C, N and P densities, and C/N/P ratios in a growing season for five vegetation patch types dominated by palatable plant species Stipa purpurea, S. purpurea and Poa litwinowiana, and unpalatable plant species Leontopodium nanum, Artemisia nanschanica, and Oxytropis glacialis. Results and discussion: Soil C and N as well as shoot and root densities varied among patch types, but not soil C/N. Patches dominated by unpalatable plant species had a lower SOC density, lower soil and plant N/P ratios, and greater plant nutrient densities than those dominated by palatable plant species. Vegetation patch type strongly influenced nutrient densities and ratios in soil-plant systems, and sampling only areas dominated by palatable plant species may overestimate the C sequestration rate at the ecosystem scale. Conclusions: Even though patch-level plant biomass and nutrient density may increase with increasing degradation, the decrease in palatability and SOC storage at the ecosystem scale would impair grassland sustainability as alpine grassland degradation proceeds. The palatability of plants should thus be considered for improving regional SOC stock estimate in future research.

28132. 题目: Response of microorganisms in biofilm to sulfadiazine and ciprofloxacin in drinking water distribution systems
文章编号: N18111710
期刊: Chemosphere
作者: Haibo Wang, Chun Hu, Yi Shen, Baoyou Shi, Dan Zhao, Xueci Xing
更新时间: 2018-11-17
摘要: Effects of sulfadiazine and ciprofloxacin on microorganisms in biofilm of drinking water distribution systems (DWDSs) were studied. The results verified that the increases of 16S rRNA for total bacteria and bacterial genus Hyphomicrobium were related to the promotion of antibiotic resistance genes (ARGs) and class 1 integrons (int1) in DWDSs with sulfadiazine and ciprofloxacin. Moreover, the bacteria showed higher enzymatic activities in DWDSs with sulfadiazine and ciprofloxacin, which resulted in more production of extracellular polymeric substances (EPS). The higher contents of EPS proteins and secondary structure β-sheet promoted bacterial aggregation and adsorption onto surface of pipelines to form biofilm. EPS can serve as a barrier for the microorganisms in biofilm. Therefore, the biofilm bacterial communities shifted and the 16S rRNA for total bacteria increased in DWDSs with antibiotics, which also drove the ARGs promotion. Furthermore, the two antibiotics exhibited stronger combined effects than that caused by sulfadiazine and ciprofloxacin alone.
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28133. 题目: Fate of microbial pollutants and evolution of antibiotic resistance in three types of soil amended with swine slurry
文章编号: N18111709
期刊: Environmental Pollution
作者: Qianwen Sui, Junya Zhang, Meixue Chen, Rui Wang, Yawei Wang, Yuansong Wei
更新时间: 2018-11-17
摘要: Swine waste is a reservoir of microbial pollutants, including pathogens, antibiotic resistance genes (ARGs) and antibiotic resistant bacteria (ARB); therefore, soil fertilized with swine waste is an essential pathway for the dissemination of microbial pollutants from concentrated swine farms to the public. To rationalize the intervals of swine wastes application and investigate the effects of soil type on the occurrences of microbial pollutants and antibiotic resistance, pot experiments were conducted with three typical soils, humic acrisol, calcaric cambisols and histosols, being collected from south, northwest and northeast China (soil-R, soil-Y and soil-B, respectively). The soils were amended with swine slurry, digestate and chemical fertilizers and then conducted for 172 days. The influence of microbial pollutants and antibiotic resistance in soil posed by digestate application was similar to that of the chemical fertilizers, while swine slurry posed high risks to the soil. Soil-B which had the highest organic matter and neutral pH was least influenced by the swine slurry amendment. tetG, tetM and ermF were persistent ARGs in the slurry treated soil, and their decay rates fitted to first-order kinetics in the order soil-B> soil-Y > soil-R. Putative pathogens showed strong correlations with ARGs, suggesting a risk of dissemination. The initial 43–82 days was the active phase of microbial pollution in slurry treated soil, during which time heavy metals, moisture content, total organic carbon and the microbial community were key factors contributing to changes in antibiotic resistance. Fertilization intervals of livestock wastes should be lengthened over the ARG active phase.
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28134. 题目: Distributions of organophosphate flame retardants (OPFRs) in three dust size fractions from homes and building material markets
文章编号: N18111708
期刊: Environmental Pollution
作者: Lingli Zhou, Wilhelm Püttmann
更新时间: 2018-11-17
摘要: The distributions of organophosphate flame retardants (OPFRs) in various size fractions of indoor dust samples from homes (H; n = 18) and building material markets (B; n = 7) in the Rhine/Main region of Germany were investigated. Three particle size fractions (F1: 150–200 μm, F2: 63–150 μm, and F3: <63 μm) and bulk dust (BD) subsamples (<200 μm) of each sample were analyzed for 10 OPFRs. On average, the total OPFR concentrations (∑₁₀OPFR) in bulk dust and all three size fractions from building material markets were 133, 153, 196, and 88.0 μg/g in subsamples B-BD, B-F1, B-F2, and B-F3. These concentrations were at least five times higher than those in bulk dust and all three size fractions from homes, with values of 19.3, 17.2, 19.5, and 18.7 μg/g for subsamples H-BD, H-F1, H-F2, and H-F3, respectively. Tris(2-chloroisopropyl)phosphate (TCIPP) was the dominant congener in dust from building material markets, contributing over 91% to the ∑₁₀OPFR of B-BD and all particle size fractions. Meanwhile, both tris(2-butoxyethyl)phosphate (TBOEP) and TCIPP were abundant in dust from homes, respectively contributing 28%–41% and 31%–43% to the ∑₁₀OPFR of H-BD and all particle size fractions. Most of the OPFR concentrations showed no consistent trend with particle size. However, TCIPP was more likely to be enriched in F2. Microscopic examination indicated that TCIPP in indoor dust mainly originated from abraded fragments of commercial products. In contrast, TBOEP accumulated in F3, related to direct transfer of floor-care products to fine dust particles. The concentrations of OPFRs were not significantly correlated with total organic carbon contents in any particle size fraction. However, evaluation of their mass contributions showed that more than 85% of OPFRs accumulated in particles smaller than 150 μm, indicating that this particle size fraction is most suitable for monitoring of OPFRs.
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28135. 题目: Stable-isotope probing of bacterial community for DIC utilization in Microcystis aeruginosa-dominated eutrophic water
文章编号: N18111707
期刊: Journal of Environmental Sciences
作者: Weiguo Zhang, Jiangye Li, Chengcheng Wang, Xue Zhou, Yan Gao, Zhongjun Jia
更新时间: 2018-11-17
摘要: Dissolved inorganic carbon (DIC) is an important source of carbon in aquatic ecosystems, especially under conditions of increased frequency of cyanobacterial bloom. However, the importance of bacteria in direct or indirect utilization of DIC has been widely overlooked in eutrophic freshwater. To identify the functional bacteria that can actively utilize DIC in eutrophic freshwater during cyanobacterial bloom, stable-isotope probing (SIP) experiments were conducted on eutrophic river water with or without inoculation with cyanobacteria (Microcystis aeruginosa). Our 16S rRNA sequencing results revealed the significance of Betaproteobacteria, with similar relative abundance as Alphaproteobacteria, in the active assimilation of H¹³CO₃⁻ into their DNA directly or indirectly, which include autotrophic genera Betaproteobacterial ammonia-oxidizing bacteria. Other bacterial groups containing autotrophic members, e.g. Planctomycetes and Nitrospira, also presented higher abundance among free-living bacteria in water without cyanobacteria. Microcystis aggregates showed a preference for some specific bacterial members that may utilize H¹³CO₃⁻ metabolized by Microcystis as organic matter, e.g. Bacteroidetes (Cytophagales, Sphingobacteriales), and microcystin-degrading bacteria Betaproteobacteria (Paucibacter/Burkholderiaceae). This study provides some valuable information regarding the functional bacteria that can actively utilize DIC in eutrophic freshwater.
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28136. 题目: Assessing the capacity of biochar to stabilize copper and lead in contaminated sediments using chemical and extraction methods
文章编号: N18111706
期刊: Journal of Environmental Sciences
作者: Mingming Wang, Liangsuo Ren, Dayang Wang, Cai Zuansi, Xuefeng Xia, Aizhong Ding
更新时间: 2018-11-17
摘要: Because of its high adsorption capacity, biochar has been used to stabilize metals when remediating contaminated soils; to date, however, it has seldom been used to remediate contaminated sediment. A biochar was used as a stabilization agent to remediate Cu- and Pb-contaminated sediments, collected from three locations in or close to Beijing. The sediments were mixed with a palm sawdust gasified biochar at a range of weight ratios (2.5%, 5%, and 10%) and incubated for 10, 30, or 60 days. The performance of the different treatments and the heavy metal fractions in the sediments were assessed using four extraction methods, including diffusive gradients in thin films, the porewater concentration, a sequential extraction, and the toxicity characteristic leaching procedure. The results showed that biochar could enhance the stability of heavy metals in contaminated sediments. The degree of stability increased as both the dose of biochar and the incubation time increased. The sediment pH and the morphology of the metal crystals adsorbed onto the biochar changed as the contact time increased. Our results showed that adsorption, metal crystallization, and the pH were the main controls on the stabilization of metals in contaminated sediment by biochar.
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28137. 题目: The binding properties of copper and lead onto compost-derived DOM using Fourier-transform infrared, UV–vis and fluorescence spectra combined with two-dimensional correlation analysis
文章编号: N18111705
期刊: Journal of Hazardous Materials
作者: Xu-Jing Guo, Xiao-Song He, Chong-Wei Li, Nan-Xi Li
更新时间: 2018-11-17
摘要: Three dissolved organic matter (DOM) samples were obtained from municipal solid wastes at the initial (C0), high-temperature (C7) and mature (C51) period during composting. Two-dimensional correlation spectroscopy (2D-COS) analysis on Fourier-transform infrared (FTIR), ultraviolet visible (UV–vis), and synchronous fluorescence spectra (SFS) were used to investigate the metal binding properties of compost-derived DOM. Synchronous and asynchronous maps of 2D-FTIR-COS of DOM-Cu(II) and DOM-Pb(II) were similar, however, the susceptibility and binding sequence of the corresponding spectral region was different. The N-H (amide I), phenolic OH, and C–O of alcohols, ethers, and esters were the most susceptive in the C0, C7, and C51 samples, respectively. 2D absorption COS indicated that the preferential binding with Cu(II) was shown to be at 305 nm for C0, at 236 nm for C7 and C51, and with Pb(II) at 247 nm for C0, at 233 nm for C7 and C51. 2D-SFS-COS indicated that protein-like matter showed a higher susceptibility and preferential binding with Cu(II) than humic-like substances. DOM showed a higher complexing affinity with Cu(II) than Pb(II) on the basis of the log K values. Spectral techniques combined with 2D-COS are useful to understand the binding heterogeneities of ligand sites within DOM-Cu(II) or Pb(II) during the composting.
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28138. 题目: Sunlight induced aggregation of dissolved organic matter: Role of proteins in linking organic carbon and nitrogen cycling in seawater
文章编号: N18111704
期刊: Science of The Total Environment
作者: Luni Sun, Wei-Chun Chin, Meng-Hsuen Chiu, Chen Xu, Peng Lin, Kathleen A. Schwehr, Antonietta Quigg, Peter H. Santschi
更新时间: 2018-11-17
摘要: Organic matter export from the euphotic zone is a key component of oceanic carbon (C) and nitrogen (N) cycles. Although interactions between these two cycles are important, studies on geochemical processes to directly connect them are limited. Here we show that sunlight can induce chemical aggregation of dissolved organic matter (DOM) into high N containing photo-aggregates. The size of microgels in natural coastal seawaters increased by18~25% compared to corresponding dark controls. Within a relatively short time (1 h), the C and N sequestered into the photo-aggregates accounted for 10% and 13% of the bulk particulate C and N, respectively. The N/C ratio of the photo-aggregates was two times higher after sunlight irradiation. Furthermore, we show that the aggregation process was dependent on reactive oxygen species (ROS). To accommodate for the different organic material in the marine environment, we monitored the particle size in various extracellular polymeric substances (EPS) and model biopolymers using flow cytometry, dynamic laser scattering, and scanning electron microscopy. We found that proteins play important roles in light-induced aggregation, which is in contrast to previous views that sunlight can break down DOM and interrupt aggregation. The photo-flocculation process involving organic N provides new insights into DOM assembly, bioavailability, and sedimentation, and thus potentially link the C and N cycles.
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28139. 题目: Roles of magnetic particles in magnetic seeding coagulation-flocculation process for surface water treatment
文章编号: N18111703
期刊: Separation and Purification Technology
作者: Miao Lv, Zhaohan Zhang, Jiayue Zeng, Junfeng Liu, Muchen Sun, Ravi S. Yadav, Yujie Feng
更新时间: 2018-11-17
摘要: Magnetic seeding coagulation-flocculation (MCF) process was evaluated by jar tests compared to a reference coagulation-flocculation (CF) process. Steps were made toward elucidating the underlying roles of magnetic particles (MPs) in MCF process. The results indicated that MPs addition could significantly accelerate flocs sedimentation and enhance pollutants removal. With an optimal strategy of adding the composite PACl/MPs (MPACl, 15/30 mg/L) first followed by 0.4 mg/L PAM, turbidity, UV₂₅₄ and TP were removed up to 96.7%, 80.8% and 95.7% in 5 min under applied magnetic field (0.5 T). In addition, the multifunction of MPs reduced the negative impacts of pH changes, resulting in a wider working pH range. Humic acid-like components adsorbed on MPs and MPs-Al species improved the UV₂₅₄ removal in MCF process than that in CF process. For low turbidity water, MPs increased suspended particles concentration and served as nuclei to enhance the formation of settleable flocs, consistent with an increase in turbidity removal from 89.75% to 96.80%. The multiple roles of MPs (suspended particles, adsorbents and coagulants) in MCF process were thoroughly discussed. This study provides theoretical guidance for its application in real surface water treatment.
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28140. 题目: Decoupling of priming and microbial N mining during a short-term soil incubation
文章编号: N18111702
期刊: Soil Biology and Biochemistry
作者: Birgit Wild, Jian Li, Johanna Pihlblad, Per Bengtson, Tobias Rütting
更新时间: 2018-11-17
摘要: Soil carbon (C) and nitrogen (N) availability depend on the breakdown of soil polymers such as lignin, chitin, and protein that represent the major fraction of soil C and N but are too large for immediate uptake by plants and microorganisms. Microorganisms may adjust the production of enzymes targeting different polymers to optimize the balance between C and N availability and demand, and for instance increase the depolymerization of N-rich compounds when C availability is high and N availability low (“microbial N mining”). Such a mechanism could mitigate plant N limitation but also lie behind a stimulation of soil respiration frequently observed in the vicinity of plant roots (“priming effect”). We here compared the effect of increased C and N availability on the depolymerization of native bulk soil organic matter (SOM), and of ¹³C-enriched lignin, chitin, and protein added to the same soil in two complementary ten day microcosm incubation experiments. A significant reduction of chitin depolymerization (described by the recovery of chitin-derived C in the sum of dissolved organic, microbial and respired C) upon N addition indicated that chitin was degraded to serve as a microbial N source under low-N conditions and replaced in the presence of an immediately available alternative. Protein and lignin depolymerization in contrast were not affected by N addition. Carbon addition enhanced microbial N demand and SOM decomposition rates, but significantly reduced lignin, chitin, and protein depolymerization. Our findings contrast the hypothesis of increased microbial N mining as a key driver behind the priming effect and rather suggest that C addition promoted the mobilization of other soil C pools that replaced lignin, chitin, and protein as microbial C sources, for instance by releasing soil compounds from mineral bonds. We conclude that SOM decomposition is interactively controlled by multiple mechanisms including the balance between C vs N availability. Disentangling these controls will be crucial for understanding C and N cycling on an ecosystem scale.