论文检索

总访问量：5100990次

总访客量：270541人

所有论文

30721. 题目: Nitrogen and Phosphorus Loads to Temperate Seepage Lakes Associated With Allochthonous Dissolved Organic Carbon Loads
文章编号: N18060510
期刊: Geophysical Research Letters
作者: J. R.Corman, B. L.Bertolet, N. J.Casson, S. D.Sebestyen, R. K.Kolka, E. H.Stanley
更新时间: 2018-06-05
摘要: Terrestrial loads of dissolved organic matter (DOM) have increased in recent years in many north temperate lakes. While much of the focus on the “browning” phenomena has been on its consequences for carbon cycling, much less is known about how it influences nutrient loading to lakes. We characterize potential loads of nitrogen and phosphorus to seepage lakes in northern Wisconsin, USA, based on a laboratory soil leaching experiment and a model that includes landscape cover and watershed area. In these seepage lakes, nutrient concentrations are positively correlated with dissolved organic carbon concentrations (nitrogen: r = 0.68, phosphorus: r = 0.54). Using long‐term records of browning, we found that dissolved organic matter‐associated nutrient loadings may have resulted in substantial increases in nitrogen and phosphorus in seepage lakes and could account for currently observed nutrient concentrations in the lake. “Silent” nutrient loadings to brown‐water lakes may lead to future water‐quality concerns.

30722. 题目: Characterization, origin and aggregation behavior of colloids in eutrophic shallow lake
文章编号: N18060509
期刊: Water Research
作者: Huacheng Xu, Mengwen Xu, Yani Li, Xin Liu, Laodong Guo, Helong Jiang
更新时间: 2018-06-05
摘要: Stability of colloidal particles contributes to the turbidity in the water column, which significantly influences water quality and ecological functions in aquatic environments especially shallow lakes. Here we report characterization, origin and aggregation behavior of aquatic colloids, including natural colloidal particles (NCPs) and total inorganic colloidal particles (TICPs), in a highly turbid shallow lake, via field observations, simulation experiments, ultrafiltration, spectral and microscopic, and light scattering techniques. The colloidal particles were characterized with various shapes (spherical, polygonal and elliptical) and aluminum-, silicon-, and ferric-containing mineralogical structures, with a size range of 20–200 nm. The process of sediment re-suspension under environmentally relevant conditions contributed 78–80% of TICPs and 54–55% of NCPs in Lake Taihu, representing an important source of colloids in the water column. Both mono- and divalent electrolytes enhanced colloidal aggregation, while a reverse trend was observed in the presence of natural organic matter (NOM). The influence of NOM on colloidal stability was highly related to molecular weight (MW) properties with the high MW fraction exhibiting higher stability efficiency than the low MW counterparts. However, the MW-dependent aggregation behavior for NCPs was less significant than that for TICPs, implying that previous results on colloidal behavior using model inorganic colloids alone should be reevaluated. Further studies are needed to better understand the mobility/stability and transformation of aquatic colloids and their role in governing the fate and transport of pollutants in natural waters.
图文摘要:

30723. 题目: New Constraints on the Abundance and Composition of Organic Matter on Ceres
文章编号: N18060508
期刊: Geophysical Research Letters
作者: Hannah H.Kaplan, Ralph E.Milliken, Conel M. O'D.Alexander
更新时间: 2018-06-05
摘要: Near‐infrared reflectance spectra from the Dawn mission at Ceres were recently found to exhibit a 3.4 μm absorption indicative of the presence of aliphatic organic compounds. Constraints on abundance and composition of these organics are necessary to inform discussions of their origin. We model reflectance spectra of organic‐bearing regions on Ceres using laboratory spectra of insoluble organics of known composition extracted from terrestrial sedimentary rocks (i.e., kerogens) and carbonaceous chondrite meteorites (i.e., insoluble organic matter, IOM). The 3.4 μm aliphatic organic absorptions observed in Dawn near‐infrared data are stronger than those observed in lab spectra of carbonaceous chondrites, and modeling requires 45% to 65% spectral fraction of IOM to fit spectra from Ceres. The spectral fraction of kerogen necessary to fit the same Ceres spectra ranges from 5% to 15% depending on the hydrogen to carbon ratio of the kerogen. Any proposed mechanism of organic delivery or formation on Ceres should explain the presence of highly concentrated IOM or why the composition is distinct from meteorite‐derived IOM if lower organic abundances are considered more plausible.

30724. 题目: Effect of organic matter on the performance and N2O emission of a granular sludge anammox reactor
文章编号: N18060507
期刊: Environmental Science: Water Research & Technology
作者: Mingsheng Jia, Celia M. Castro-Barros, Mari Winkler, Eveline Volcke
更新时间: 2018-06-05
摘要: A continuously fed bubble column granular sludge anammox reactor was operated for 405 days to investigate the effect of organic matter on the reactor performance and N2O emission. Results showed that influent COD improved the nitrogen removal of the anammox reactor at low influent COD/TN ratios (ca. 0.1); however, a concurrent increase in N2O emission was observed. The average N2O emission increased by 2.5 times (p < 0.05) with increasing influent COD concentration, accounting for up to 0.46% of the incoming nitrogen load. A generalized method was demonstrated and applied to derive the anammox stoichiometry from experimental data for improved mass balance. Mass balance revealed that approximately 18% of the nitrate produced from anammox conversion was reduced via heterotrophic denitrification to nitrite, and 29% of this produced nitrite was further released as N2O. In addition, it was found that the experimentally measured anammox biomass yield in the overall metabolic reaction has been mistakenly used as the catabolic yield in many modelling studies. Solutions were proposed.
图文摘要:

30725. 题目: Link between dissolved organic matter transformation and process performance in a membrane bioreactor for urinary nitrogen stabilization
文章编号: N18060506
期刊: Environmental Science: Water Research & Technology
作者: Celine Jacquin, Mathias Monnot, Razina Hamza, Yahaut Kouadio, Francois Zaviska, Tony Merle, Geoffroy Lesage, Marc Heran
更新时间: 2018-06-05
摘要: A lab-scale membrane bioreactor was fed with fresh urine collected from source separation public toilets to perform full nitrification, urinary nitrogen stabilization and effluent sanitation. After acclimation, a nitrogen loading rate (NLR) of 1.2 kg TN per m3 d-1 was reached with an average nitrification rate of 98.3%. Dissolved organic matter (DOM) transformation was studied within the MBR to identify biomass activity indicators that could be used for process optimization. By combining three-dimensional excitation emission fluorescence (3DEEM) and liquid chromatography coupled with organic carbon detection, nitrogen detection and UV detection (LC-OCD-OND-UVD), it was possible to investigate the transformation and fate of urine DOM during biological reactions and membrane separation. Results show that urine is mainly composed of low molecular weight molecules (<1000 Da) easily consumed by the active biomass. This consumption came with the production of soluble microbial products (SMP): biopolymers and humic substances. Significant correlations were observed between 3DEEM indicators and the NLR values. Biopolymers were mainly retained by the membrane and tended to accumulate in the reactor, which was of major interest since they were identified as DOM consumed by the active biomass in case of system instabilities. Humic substances were slightly retained by the membrane and mostly implied in irreversible fouling. This original approach allowed highlighting the quick active biomass acclimation under challenging conditions of high strength ammonia solutions such as urine.
图文摘要:

30726. 题目: The performance of a sulfate-radical mediated advanced oxidation process in the degradation of organic matter from secondary effluents
文章编号: N18060505
期刊: Environmental Science: Water Research & Technology
作者: Dayang Wang, Lirong Cheng, Mingming Wang, Xuezhen Zhang, Dong Xue, Wenjing Zhuo, Lei Zheng, Aizhong Ding
更新时间: 2018-06-05
摘要: The effects of sulfate radical-mediated advanced oxidation processes with transition metal and energy activation methods were investigated during effluent organic matter (EfOM) degradation. The results showed that transition metal systems and energy systems performed well with some outstanding EfOM removal efficiencies. Specifically, the EfOM removal rate with the Ag(I)/PS (persulfate) system reached 90%, which was far greater than those of Co(II)/PMS (peroxymonosulfate) (56%) and ZVI (zero valence iron)/PS (58%), respectively. Regarding the energy activation systems, they all exhibited both better combined efficiency and the highest efficiency at strong energy intensity (such as heating at 80 °C or treating with UV at 40 W). Further analysis by UV-visible spectroscopy during the reaction process provided a better understanding of the overall changes in every system.
图文摘要:

30727. 题目: Performance of a seawater-driven forward osmosis process for pre-concentrating digested sludge centrate: organic enrichment and membrane fouling
文章编号: N18060504
期刊: Environmental Science: Water Research & Technology
作者: Minh Truong Vu, Ashley Joy Ansari, Faisal I. Hai, Long Nghiem
更新时间: 2018-06-05
摘要: This study demonstrated the potential of seawater-driven forward osmosis for enriching organic matter in digested sludge centrate. The results indicated that the cellulose triacetate membrane offered better performance than the polyamide membrane in terms of organic materials enrichment, fouling resistance and membrane cleaning efficiency. Membrane fouling decreased the enrichment efficiency of organic matter since the deposition of suspended particulate matter on the membrane surface caused fouling and loss of organic matter from the concentrated sludge centrate. The results showed that increasing the draw solution concentration increased flux but did not aggravate membrane fouling, however, it could reduce the efficiency of physical flushing to recover the flux. Seawater showed comparable forward osmosis performance to that of analytical grade NaCl as draw solutes in terms of flux and organic enrichment. The results also showed that seawater as the draw solution resulted in more membrane fouling and lower flux recovery compared to NaCl.
图文摘要:

30728. 题目: Effect of humic acid & bacterial exudates on sorption-desorption interactions of 90Sr with brucite
文章编号: N18060503
期刊: Environmental Science: Processes Impacts
作者: Hollie Ashworth, Liam Abrahamsen-Mills, Nick Bryan, Lynn Foster, Jonathan R. Lloyd, Simon Kellet, Sarah Heath
更新时间: 2018-06-05
摘要: One of the nuclear fuel storage ponds at Sellafield (United Kingdom) is open to the air, and has contained a significant inventory of corroded magnox fuel and sludge for several decades. As a result, some fission products have also been released into solution. 90Sr is known to constitute a small mass of the radionuclides present in the pond, but due to its solubility and activity, it is at risk of challenging effluent discharge limits. The sludge is predominantly composed of brucite (Mg(OH)2), and organic molecules are known to be present in the pond liquor with occasional algal blooms restricting visibility. Understanding the chemical interactions of these components is important to inform ongoing sludge retrievals and effluent management. Additionally, interactions of radionuclides with organics at high pH will be an important consideration for the evolution of cementitious backfilled disposal sites in the UK. Batch sorption–desorption experiments were performed with brucite, 90Sr and natural organic matter (NOM) (humic acid (HA) and Pseudanabaena catenata cyanobacterial growth supernatant) in both binary and ternary systems at high pH. Ionic strength, pH and order of addition of components were varied. 90Sr was shown not to interact strongly with the bulk brucite surface in binary systems under pH conditions relevant to the pond. HA in both binary and ternary systems demonstrated a strong affinity for the brucite surface. Ternary systems containing HA demonstrated enhanced sorption of 90Sr at pH 11.5 and vice versa, likely via formation of strontium–humate complexes regardless of the order of addition of components. The distribution coefficients show HA sorption to be reversible at all pH values studied, and it appeared to control 90Sr behaviour at pH 11.5. Ternary systems containing cyanobacterial supernatant demonstrated a difference in 90Sr behaviour when the culture had been subjected to irradiation in the first stages of its growth.
图文摘要:

30729. 题目: Experimental methodology to measure the reaction rate constants of processes sensitised by the triplet state of 4-carboxybenzophenone as proxy of the triplet states of chromophoric dissolved organic matter, under steady-state irradiation conditions
文章编号: N18060502
期刊: Environmental Science: Processes Impacts
作者: Marco Minella, Lorenzo Rapa, Luca Carena, Marco Pazzi, Valter Maurino, Claudio Minero, Marcello Brigante, Davide Vione
更新时间: 2018-06-05
摘要: By a combination of transient absorption spectroscopy and steady-state irradiation experiments, we investigated the transformation of phenol and furfuryl alcohol (FFA) sensitised by irradiated 4-carboxybenzophenone (CBBP). The latter is a reasonable proxy molecule to assess the reactivity of the excited triplet states of the chromophoric dissolved organic matter that occurs in natural waters. The main reactive species for the transformation of both phenol and FFA was the CBBP triplet state, despite the fact that FFA is a commonly used probe for 1O2. In the case of FFA it was possible to develop a simple kinetic model that fitted well the experimental data obtained by steady-state irradiation, in a wide range of FFA concentration values. In the case of phenol the model was made much more complex by the likely occurrence of back reactions between radical species (e.g., phenoxyl and superoxide). This problem can be tackled by considering only the experimental data at low phenol concentration, where the degradation rate increases linearly with concentration. We do not recommend the use of 1O2 scavengers/quenchers such as sodium azide to elucidate CBBP photoreaction pathways, because the azide provides misleading results by also acting as a triplet-state quencher. Based on the experimental data, we propose a methodology for the measurement of the CBBP triplet-sensitisation rate constants from steady-state irradiation experiments, allowing for a better assessment of the triplet-sensitised degradation of emerging contaminants.
图文摘要:

30730. 题目: Evaluation of the UV/H 2 O 2 system for treating natural water with a mixture of anthracene and benzo[a]pyrene at ultra-trace levels
文章编号: N18060501
期刊: Environmental Science and Pollution Research
作者: Ainhoa Rubio-Clemente, Edwin Chica, Gustavo Pe?uela
更新时间: 2018-06-05
摘要: The presence of polycyclic aromatic hydrocarbons, such as anthracene (AN) and benzo[a]pyrene (BaP), in water has become a problem of great concern due to the detrimental health effects caused to humans and living beings. In this work, the efficiency of the UV/H2O2 system for degrading the target compounds at ultra-trace levels in surface water has been evaluated. For this purpose, a previous optimization step using a face-centered central composite experimental design has been conducted, considering the effect of the UV-C irradiance and the initial concentration of H2O2. It was evidenced that under optimal operating conditions (11 mg L-1 H2O2 and 0.63 mW cm-2 irradiance), AN and BaP removal percentages were higher than 99.8%. Additionally, 69.3% of the organic matter, in terms of total organic carbon, was mineralized without the production of transformation by-products more harmful than the parent compounds. These findings demonstrate the oxidation capacity of the examined system in a natural matrix for degrading micropollutants that cannot be converted through conventional treatment processes. Consequently, new horizons are opened for the effective use of the UV/H2O2 system for drinking water production, providing the accomplishment of other regulated parameters related to water quality.

30731. 题目: Photochemical detoxification of Cr(VI) using iron and saccharic acid: insights from cytotoxic and genotoxic assays
文章编号: N18060406
期刊: Environmental Science: Water Research & Technology
作者: Gokulakrishnan Subramanian, Ganugapati Sai Srivatsa Kumar, Venkatraman Ravi, Nagalingam Ravi Sundaresan, Giridhar Madras
更新时间: 2018-06-04
摘要: Herein, we demonstrate rapid and complete photochemical detoxification of Cr(VI) by iron using saccharic acid (SA) as a sacrificial organic agent. 100% Cr(VI) (200 μM) was reduced within 30 min using Fe(III) (50 μM) and SA (300 μM) under UV irradiation. The reaction mechanism involves photochemical recycling of Fe(III)/Fe(II) by SA via ligand to metal charge transfer (LMCT) along with the generation of a concomitant ligand radical and hydroperoxyl radical. Importantly, the MTT assay and γH2AX immunostaining were performed to evaluate the hitherto unexplored comparison of cytotoxicity and genotoxicity caused by untreated and treated aqueous Cr(VI). The results revealed that the Fe(III)/SA/UV treatment caused the complete removal of cytotoxic and genotoxic effects of Cr(VI) towards human cell lines. The presence of nitrate, chloride and natural organic matter increased the Cr(VI) reduction, while phosphate decreased the Cr(VI) reduction. Cu(II), Al(III) and Ni(II) had a positive effect on the Cr(VI) reduction. Furthermore, the Fe(III)/SA/UVC treatment caused almost complete Cr(VI) reduction in groundwater, lake water, and simulated galvanic wastewater. This study strongly supports the aptness of the Fe(III)/SA photochemical system for detoxification of Cr(VI) contaminated wastewater.
图文摘要:

30732. 题目: Interannual sedimentary effluxes of alkalinity in the southern North Sea: model results compared with summer observation...
文章编号: N18060405
期刊: Biogeosciences
作者: Johannes P?tsch, Wilfried Kühn, and Katharina Dorothea Six
更新时间: 2018-06-04
摘要: For the sediments of the central and southern North Sea different sources of alkalinity generation are quantified by a regional modelling system for the period 2000–2014. For this purpose a formerly global ocean sediment model coupled with a pelagic ecosystem model is adapted to shelf sea dynamics, where much larger turnover rates than in the open and deep ocean occur. To track alkalinity changes due to different nitrogen-related processes, the open ocean sediment model was extended by the state variables particulate organic nitrogen (PON) and ammonium. Directly measured alkalinity fluxes and those derived from Ra isotope flux observation from the sediment into the pelagic are reproduced by the model system, but calcite building and calcite dissolution are underestimated. Both fluxes cancel out in terms of alkalinity generation and consumption. Other simulated processes altering alkalinity in the sediment, like net sulfate reduction, denitrification, nitrification, and aerobic degradation, are quantified and compare well with corresponding fluxes derived from observations. Most of these fluxes exhibit a strong positive gradient from the open North Sea to the coast, where large rivers drain nutrients and organic matter. Atmospheric nitrogen deposition also shows a positive gradient from the open sea towards land and supports alkalinity generation in the sediments. An additional source of spatial variability is introduced by the use of a 3-D heterogenous porosity field. Due to realistic porosity variations (0.3–0.5) the alkalinity fluxes vary by about 4 %. The strongest impact on interannual variations of alkalinity fluxes is exhibited by the temporal varying nitrogen inputs from large rivers directly governing the nitrate concentrations in the coastal bottom water, thus providing nitrate necessary for benthic denitrification. Over the time investigated the alkalinity effluxes decrease due to the decrease in the nitrogen supply by the rivers.

30733. 题目: Nanoecotoxicity assessment of graphene oxide and its relationship with humic acid
文章编号: N18060404
期刊: Environmental Toxicology and Chemistry
作者: Vera L. Castro, Zaira Clemente, Claudio Jonsson, Mariana Silva, José Henrique Vallim, Aline Maria Zigiotto de Medeiros, Diego Stéfani T. Martinez
更新时间: 2018-06-04
摘要: The risk assessment of nanomaterials is essential for regulatory purposes and for sustainable nanotechnological development. Although the application of graphene oxide has been widely exploited, its environmental risk is not well understood because several environmental conditions can affect its behavior and toxicity. In the present study, the graphene oxide effect from aquatic ecosystems was assessed considering the interaction with humic acid on 9 organisms: Raphidocelis subcapitata (green algae), Lemna minor (aquatic plant), Lactuca sativa (lettuce), Daphnia magna (planktonic microcrustacean), Artemia salina (brine shrimp), Chironomus sancticaroli (Chironomidae), Hydra attenuata (freshwater polyp), and Caenorhabditis elegans and Panagrolaimus sp. (nematodes). The no‐observed‐effect concentration (NOEC) was calculated for each organism. The different criteria used to calculate NOEC values were transformed and plotted as a log‐logistic function. The hypothetical 5 to 50% hazardous concentration values were, respectively, 0.023 (0.005–0.056) and 0.10 (0.031–0.31) mg L-1 for graphene oxide with and without humic acid, respectively. The safest scenario associated with the predicted no‐effect concentration values for graphene oxide in the aquatic compartment were estimated as 20 to 100 μg L-1 (in the absence of humic acid) and 5 to 23 μg L-1 (in the presence of humic acid). Finally, the present approach contributed to the risk assessment of graphene oxide–based nanomaterials and the establishment of nano‐regulations.

30734. 题目: Effects of multiple environmental factors on the growth and extracellular organic matter production of Microcystis aeruginosa : a central composite design response surface model
文章编号: N18060403
期刊: Environmental Science and Pollution Research
作者: Mengqi Jiang, Zheng Zheng
更新时间: 2018-06-04
摘要: In this study, statistically designed experiments using response surface methodology were conducted on Microcystis aeruginosa. A central composite design response surface model was established to investigate the multiple effects of various physical and chemical factors (total nitrogen, total phosphorus, temperature, and light intensity) on algal density and extracellular organic matter. The results of the experiments reveal that nitrate and phosphate had significant interactive effects on algal density, both iron and light intensity had synergic effects on the production of microcystins (MC-LR) and extracellular polysaccharides (EPS), and light intensity and nitrite had clear interactive effects on EPS release. Results did not show significant interactive effects on extracellular dissolved organic carbon (DOC) production. The contribution of extracellular dissolved organic matter of Microcystis aeruginosa during the logarithmic phase was further identified using a three-dimensional excitation emission matrix (3-DEEM). This study contributes to our theoretical knowledge of the prediction and analysis of M. aeruginosa growth and extracellular organic matter production.

30735. 题目: Impact of tryptophan on the formation of TCNM in the process of UV/chlorine disinfection
文章编号: N18060402
期刊: Environmental Science and Pollution Research
作者: Lin Deng, Longjia Wen, Wenjuan Dai, Rajendra Prasad Singh
更新时间: 2018-06-04
摘要: Low-pressure (LP) UV treatment after chlorine disinfection was associated with enhanced formation of trichloronitromethane (TCNM), a halonitromethane disinfection by-product (DBP), due to the chlorination of tryptophan. Evidence was found that the concentration of TCNM from tryptophan increased quickly to the maximum for the first instance. Moreover, the increase of TCNM under UV exceeded 10 times than under dark. Then, it was found to have an obvious decrease in the formation of TCNM, even finally hardly disappear. In order to elucidate reasons for this phenomenon, the effects of light intensity, initial tryptophan concentration, free chlorine concentration, pH, and tert-butanol (TBA) on the formation of TCNM were investigated under UV/chlorine treatment. Finally, the effects of tryptophan on the formation of TCNM and the direct photodegradation of TCNM under LP UV irradiation were studied for analyzing the possible pathways of TCNM formation from amino acid. Since amino acids are very common in water sources, further research into chemical oxidation of these species by LP UV and chlorine is recommended. It can help us to find the precursors of TCNM formation and reduce the risk of TCNM formation for drinking water and wastewater utilities.

30736. 题目: Persulfate activation with rice husk-based magnetic biochar for degrading PAEs in marine sediments
文章编号: N18060401
期刊: Environmental Science and Pollution Research
作者: Cheng-Di Dong, Chiu-Wen Chen, Chang-Mao Hung
更新时间: 2018-06-04
摘要: Phthalate esters (PAEs) can interfere with the endocrine systems of humans and wildlife. The main objective of this study was to evaluate the suitability of a composite for remediating marine sediments contaminated with PAEs. The composite was synthesized with magnetite nanoparticles (Fe3O4) and rice husk biochar (RHB) by using chemical co-precipitation. Fe3O4, RHB, and Fe3O4–RHB substantially activated sodium persulfate (Na2S2O8, PS) oxidation to form SO4- and thus degrade PAEs in marine sediments in a slurry system. The morphology and structural composition of the magnetic composites were examined using XRD, FTIR, environmental scanning electron microscopy–energy-dispersive X-ray spectrometry, and superconducting quantum interference device. The Fe3O4–RHB composites were confirmed to be prepared successfully. The influences of various parameters, including the PS concentration, composite loading, and initial pH, were investigated. The concentration of high-molecular-weight PAEs (HPAEs) in sediment was much higher than that of low-molecular-weight PAEs (LPAEs); di-(2-ethylhexyl) phthalate (DEHP) was an especially salient marker of PAE contamination in sediments. Furthermore, increasing the PS and Fe3O4–RHB doses accelerated PAE oxidation at pH 3.0; 83% degradation of PAEs was achieved when the PS and Fe3O4–RHB concentrations were increased to 2.3 × 10-2 mM and 1.67 g/L, respectively. LPAEs such as dibutyl phthalate (DnBP) are easier to degrade than HPAEs such as DEHP, diisononyl phthalate (DINP), and diisodecyl phthalate (DIDP). In addition, possible activation mechanisms of the interactions between S2O82- and Fe2+/Fe3+ on the Fe3O4 surface, which involve an efficient electron transfer mediator of the RHB oxygen functional groups promoting the generation of SO4- in the Fe3O4–RHB/PS system, were clarified. Thus, the Fe3O4–RHB/PS oxidation process is expected to be a viable method for remediating PAE-contaminated marine sediment.

30737. 题目: Advances in the determination of humification degree in peat since Achard (1786): Applications in geochemical and paleoenvironmental studies
文章编号: N18060303
期刊: Earth-Science Reviews
作者: Claudio Zaccone, César Plaza, Claudio Ciavatta, Teodoro M. Miano, William Shotyk
更新时间: 2018-06-03
摘要: The humification process is one of the least understood and most intriguing aspects of humus chemistry and vital to the global carbon (C) cycle. Peatlands represent the largest terrestrial reservoirs of organic C and support a unique biodiversity, but are also natural archives of climate and environmental changes. In fact, cores from ombrotrophic peatlands are commonly used to reconstruct environmental impacts by human activities during the past decades, centuries and millennia. Understanding the extent to which bogs may serve as reliable archives is of paramount importance in order to ensure that chronological information about natural and human-induced environmental changes are effectively preserved in peat deposits rather than irretrievably affected by humification. Structural changes of the organic matter which constitutes peat are often evaluated by various indirect measures of the degree of humification. Numerous methods and proxies have been proposed and used during the last century, often providing contrasting or inconsistent results. Here we tested multiple physical, chemical, spectroscopic and thermal approaches using peat samples collected from nine bogs on four continents. Despite the different climatic conditions, botanical composition, depth and age of peat formation, we show that the H/C ratio is the simplest, most widely valid and cost-effective humification proxy and should find universal application to multi-proxy geochemical and paleoenvironmental studies. Moreover, we show that three-quarters of the organic C in the studied bogs is in a comparatively undecomposed state, and thus vulnerable to climate changes.

30738. 题目: Cu2O@β-cyclodextrin as a synergistic catalyst for hydroxyl radical generation and molecular recognitive destruction of aromatic pollutants at neutral pH
文章编号: N18060302
期刊: Journal of Hazardous Materials
作者: Lingshuai Kong, Guodong Fang, Ya Kong, Meng Xie, Vinothkumar Natarajan, Dongmei Zhou, Jinhua Zhan
更新时间: 2018-06-03
摘要: Wastewater systems contain a large number of compounds, such as anthropogenic aromatic pollutants and natural organic matter (NOM), and usually have pH higher than 4. Fenton-like reaction is the most widespread method for removal of organic pollutants, but their reactivity with H2O2 may be inhibited by NOM due to the competition of hydroxyl radicals and chelating agents. In this work, Cu2O@β-cyclodextrin was developed to achieve the collaboration between molecular recognition and Fenton-like catalysis to destruct aromatic pollutants at neutral pH. In Cu2O@β-CD, covalent CuOC bond was topotaxially converted from CuCl assisted by β-CD at room temperature. Covalently linked β-CD could keep humic acid from interfering catalytic performance of Cu2O surfaces and inhibit the leaching of copper. A higher catalytic ability was observed for Cu2O@β-CD with rate constant 0.0331 min-1 than Cu2O (0.0064 min-1) at neutral pH. A mechanism of synergistic catalysis was proposed on the basis of Cu+, β-CD and phenoxo-Cu2+ complexes in the Cu2O@β-CD/BPA/H2O2 system. The strategy of coupling molecular recognition into Fenton-like reaction provides an efficient and promising approach to the destruction of aromatic pollutants at neutral pH.
图文摘要:

30739. 题目: Trends in historical mercury deposition inferred from lake sediment cores across a climate gradient in the Canadian High Arctic
文章编号: N18060301
期刊: Environmental Pollution
作者: Jennifer B. Korosi, Katherine Griffiths, John P. Smol, Jules M. Blais
更新时间: 2018-06-03
摘要: Recent climate change may be enhancing mercury fluxes to Arctic lake sediments, confounding the use of sediment cores to reconstruct histories of atmospheric deposition. Assessing the independent effects of climate warming on mercury sequestration is challenging due to temporal overlap between warming temperatures and increased long-range transport of atmospheric mercury following the Industrial Revolution. We address this challenge by examining mercury trends in short cores (the last several hundred years) from eight lakes centered on Cape Herschel (Canadian High Arctic) that span a gradient in microclimates, including two lakes that have not yet been significantly altered by climate warming due to continued ice cover. Previous research on subfossil diatoms and inferred primary production indicated the timing of limnological responses to climate warming, which, due to prevailing ice cover conditions, varied from 1850 to 1990 for lakes that have undergone changes. We show that climate warming may have enhanced mercury deposition to lake sediments in one lake (Moraine Pond), while another (West Lake) showed a strong signal of post-industrial mercury enrichment without any corresponding limnological changes associated with warming. Our results provide insights into the role of climate warming and organic carbon cycling as drivers of mercury deposition to Arctic lake sediments.
图文摘要:

30740. 题目: Polarity and molecular weight of compost-derived humic acid affect Fe(III) oxides reduction
文章编号: N18060213
期刊: Chemosphere
作者: Ying Yuan, Xiaosong He, Beidou Xi, Dan Li, Rutai Gao, Wenbing Tan, Hui Zhang, Chao Yang, Xinyu Zhao
更新时间: 2018-06-02
摘要: Whether polarity and molecular weight (MW) of compost-derived organic matters have significant impacts on their redox properties are far unknown. Our results showed that both the Fe2O3 and Fe3O4 reduction by S. oneidensis MR-1 were effectively facilitated by compost-derived humic acids (HAs) under anoxic condition. Among the 15 kinds of compost-derived components identified by the reverse phase high-performance liquid chromatography (RP-HPLC) and high-performance size exclusion chromatography (HPSEC), the relatively hydrophilic and high MW compost-derived components presented significant associations with Fe2O3 reduction, and the hydrophobic components correlated well with Fe3O4 reduction. Quinones content and aromaticity of the compost-derived HAs presented positive correlation with Fe(III) oxides reduction. These findings demonstrated the impacts of the polarity and MW of compost-derived HAs on Fe(III) oxides reduction, further suggested that compost-derived HAs could influence the geochemical behaviors of heavy metal, organic pollutants and nutrient elements in natural environment by facilitating the reduction of Fe(III) oxides, which were very useful for the improvement of composting technology and application of compost products.
图文摘要: