7721. 题目: Simulating Effluent Organic Matter Competition in Micropollutant Adsorption onto Activated Carbon Using a Surrogate Competitor
期刊: Environmental Science & Technology
作者: Stefan Dittmar, Frederik Zietzschmann, Maike Mai, Eckhard Worch, Martin Jekel, Aki S. Ruhl
摘要: Adsorption onto activated carbon is a promising option for removing organic micropollutants (OMPs) from wastewater treatment plant (WWTP) effluents. The heterogeneity of activated carbons and adsorption competition between OMPs and adsorbable compounds of the effluent organic matter (EfOM) complicate the prediction of OMP removals. Thus, reliable and simple test systems are desirable. For this study, batch experiments with powdered activated carbon (PAC) were carried out to examine methyl orange (MO) as a selected surrogate competitor to simulate EfOM adsorption competition. MO solutions were spiked with carbamazepine (CBZ) as an indicator substance for well-adsorbing OMPs. On the basis of CBZ adsorption isotherms in WWTP effluents, MO concentrations for batch test solutions with identical adsorption competition toward CBZ were calculated. The calculations were performed according to an empirical model of CBZ adsorption in the presence of MO, since predictions employing the ideal adsorbed solution theory (IAST) proved to be inaccurate. Comparative batch tests with five different PACs were conducted with WWTP effluent and respective MO batch test solutions. Except for one PAC, the achieved CBZ removals were very similar in WWTP effluent and the test solution. Additionally, a universal correlation between MO and CBZ removals was found for four PACs.
7722. 题目: Soil organic amendments: impacts on sorption of organophosphate pesticides on an alluvial soil
期刊: Journal of Soils and Sediments
作者: Omkar D. Gaonkar, Indumathi M. Nambi, Suresh Kumar Govindarajan
摘要: Purpose: Soil organic carbon enrichment by addition of organic amendments (OAs) is a common agricultural and gardening practice. Such amendments can cause ambiguous environmental effects; it could enhance the sorption of pesticides by increasing soil organic carbon content, and on the contrary, dissolved organic matter (DOM) from OAs could facilitate their leaching. This study evaluated the influence of OAs, mixed waste compost, and dried goat organic manure on the sorption of organophosphates, dichlorvos, and chlorpyrifos.Materials and methods: Soil (15 cm depth) was collected from an agricultural field and stored. Dissolved organic matter (DOM) extracted from the amendments and the amended soils was characterized by fluorescence spectroscopy and Fourier transform infrared spectroscopy (FT-IR). Initially, studies were carried out to evaluate the effect of DOM from organic amendments (OA-DOM) and dissolved humic acids (HAs) as model DOM on the sorption of selected pesticides. In the later part, OAs (2.5 and 5% w/w) were added to the soil, and sorption experiments were carried out using amended soil to understand the combined effects of insoluble and soluble organic carbon fraction. As dichlorvos sorption was found to be very low, desorption experiments were conducted only for chlorpyrifos using 0.01 M CaCl2 and DOM solutions.Results and discussion: The spectroscopic characterization of OA-DOM revealed that it mainly contained large amounts of highly humified and aromatic material. OA-DOM and HAs had a similar effect on pesticide sorption leading to a slight but not significant increase in dichlorvos sorption while a substantial reduction in chlorpyrifos sorption was observed. Surface tension analysis highlighted that OA-DOM and HAs might have caused greater solubilization of chlorpyrifos, thus reducing sorption. Further, it also promoted greater desorption of adsorbed chlorpyrifos. These results seem to be related to the humified and aromatic nature of OA-DOM and HAs, determining the interactions between hydrophobic chlorpyrifos and DOM. On the contrary, the addition of OAs to soil promoted greater chlorpyrifos and dichlorvos sorption, but a clear correlation between increase in soil organic carbon and pesticide sorption could not be established.Conclusions: The study highlighted that the net effect of OA application was an increase in pesticide sorption that depended on the nature of DOM and pesticide properties. The interactions of hydrophobic chlorpyrifos with DOM can lead to a significant reduction in sorption to such an extent that the sorption in the presence of substantial DOM concentration can be less than the sorption without it.
7723. 题目: Yields and Characterization of Dissolved Organic Matter From Different Aged Soils in Northern Alaska
期刊: Journal of Geophysical Research: Biogeosciences
作者: Lei Gao, Zhengzhen Zhou, Alberto V. Reyes, Laodong Guo
摘要: Soil organic matter (SOM) in northern high‐latitude regions is a major component of the global carbon cycle. However, the yield of soil‐dissolved organic matter (DOM) during soil‐water interactions and its chemical characteristics and reactivities remain poorly understood. We report here elemental composition and isotopic signatures of bulk‐SOM from northern Alaska, and yields of water‐leachable soil‐DOM, including dissolved organic carbon, dissolved organic nitrogen, and dissolved organic phosphorus, and nutrients (dissolved inorganic nitrogen and phosphate). The bulk‐SOM contained 5,400–373,900 μg‐C/g‐soil, 500–12,610 μg‐N/g‐soil, and 38.6–384 μg‐P/g‐soil, with a C/N ratio of 13–37 and a C/P ratio of 80–3,911. The water‐extractable dissolved organic carbon, dissolved organic nitrogen, and dissolved organic phosphorus only accounted for 0.58–2.5%, 0.91–3.4%, and 1.2–3.0% of their corresponding total soil‐OC, N, and OP, respectively. While SOM‐δ13C was less variable (-27.08‰ to -26.49‰) showing the same overall C source, 14C‐ages varied widely from 1,170 ± 20 to 16,200 ± 55 years before present, indicating different deposition‐conditions and subsequent‐processes among the soil samples. The specific‐UV‐absorbance at 254 nm (or aromaticity) of soil‐DOM differed considerably and was negatively correlated to spectral slope values. A humic‐like (C1), a low‐molecular‐weight fulvic‐like (C2), and a protein‐like component (C3) were identified as the major fluorescent‐DOM components. The C3/C2 and C3/C1 ratios generally increased with SOM‐14C‐age, suggesting a preferential degradation/transformation of humic‐like and fulvic‐like components or a transformation/production of protein‐like components within permafrost. Both biological and humification indices increased with 14C‐age, excluding the oldest soil, which pointed to a preferential preservation or transformation/production of protein‐like DOM within permafrost, implying that soil‐DOM derived from old permafrost can be highly vulnerable and readily decomposed upon permafrost thaw.
7724. 题目: Dynamics of labile and stable carbon and priming effects during composting of sludge and lop mixtures amended with low and high amounts of biochar
期刊: Waste Management
作者: Daniel Fischer, Gabriel Erben, Gerald Dunst, Bruno Glaser
摘要: This study was performed to investigate the effects of biochar amendment on the dynamics of labile and stable carbon (C) fractions and associated priming effects during composting of sludge and lop mixtures. Furthermore, the effect of aerobic composting on biochar stable C composition was analyzed.Low amounts of activated carbon [dosage 0–1.7% w/w] and higher amounts of charcoal [dosage 0–38% w/w] were applied to the organic feedstock mixture in two separated full-scale composting trials under practical field conditions. The results demonstrated that biochar-C was substantially more stable during the composting process than compost-derived organic C resulting in a significant enrichment of the stable black C fraction in the final product. Furthermore, stability of final products were significantly increased, if more biochar has been initially added prior to composting. However, labile organic C losses were increased (positive priming) if low amounts of activated carbon have been applied, while no short-term priming effects could be observed after adding charcoal over a wider application range. Moreover, biochar stable C composition was positively affected during the composting process. Based on our results, a biochar amendment ≥10% (w/w) seems generally favorable for an accelerated composting process, while stability characteristics of the final products were improved. However, some caution seems to be required concerning the usability of activated carbon due to positive priming.
7725. 题目: Herbicides degradation kinetics in soil under different herbigation systems at field scale
期刊: Soil and Tillage Research
作者: Elham Noshadi, Mehdi Homaee
摘要: Application of pesticides in agriculture is one of the main sources of soil and water contamination. Herbicides used by herbigation increases the possibility of water and soil contamination by these toxins. Thus, knowledge on degradation of herbicides in soil for selecting more efficient management strategies is necessary. The objective of this study was to quantitatively describe herbicides degradation in soil under different herbigation and conventional spraying systems in actual field conditions. Consequently, Metribuzin was applied to soil by herbigation and conventional spraying via four methods. The degradation kinetics of herbicide was determined by soil sampling of four layers over a period of 70 days. Results indicated that the herbicide degradation kinetics depends on application method and studying scale. Based on these results, at each of soil layer, degradation rate remained constant due to no changes in soil physical and chemical properties and soil moisture conditions during the experiment. In these conditions, degradation trends followed a single first order kinetics model. However, herbicide degradation kinetics at entire soil profile was different depending on application method. Once the herbicide was applied via the first irrigation, large portion of herbicide was leached out to the second, third and fourth soil layers. Owing to roughly similar clay, organic matter, moisture content along with microbial activity and population in these three layers, the degradation rate was constant, during the experiment, and degradation trend followed the single first order kinetics model. However, in other application methods, the degradation rate was inconstant as a result of remaining a large portion of herbicide in the first soil layer, as well as different soil physical, chemical and biological properties of this layer compared to other layers. This contributed to a deviation from first order kinetics. The degradation kinetics was described much better by bi-exponential model.
7726. 题目: Degradation of antibiotic ampicillin on boron-doped diamond anode using the combined electrochemical oxidation - Sodium persulfate process
期刊: Journal of Environmental Management
作者: Zacharias Frontistis, Dionissios Mantzavinos, Sureyya Meri?
摘要: In this work, the electrochemical oxidation of antibiotic ampicillin (AMP) on a boron-doped diamond anode in the presence of sodium persulfate (SPS) was investigated (EO/SPS process). Experiments were conducted at AMP concentrations between 0.8 and 3 mg/L, SPS concentrations between 100 and 500 mg/L, current densities between 5 and 110 mA/cm2, in three water matrices (ultrapure water, bottled water and secondary treated wastewater), using 0.1 M Na2SO4 as the supporting electrolyte. AMP degradation follows a pseudo-first order kinetic expression with the apparent rate constant increasing with (i) increasing SPS concentration (from 0.08 min 1 to 0.36 min 1 at 0 and 500 mg/L SPS, respectively, 1.1 mg/L AMP, 25 mA/cm2), (ii) increasing current (from 0.08 min 1 to 0.6 min 1 at 5 and 110 mA/cm2, respectively, 1.1 mg/L AMP, 250 mg/L SPS), and (iii) decreasing AMP concentration (from 0.16 min 1 to 0.31 min 1 at 3 and 0.8 mg/L, respectively, 250 mg/L SPS, 25 mA/cm2). The presence of various anions (mainly bicarbonates) in bottled water did not impact AMP degradation. The observed kinetic constant decreased by 40% in the presence of 10 mg/L humic acid. On the other hand, process efficiency was enhanced almost 3.5 times in secondary effluent due to the electrogeneration of active chlorine species that promote indirect oxidation reactions in the bulk solution. The efficacy of the EO/SPS process was compared to and found to be considerably greater than a process where SPS was activated by simulated solar irradiation at an intensity of 7.3 × 10 7 E/(L.s) (SLR/SPS process). Coupling the two processes (EO/SLR/SPS) resulted in a cumulative, in terms of AMP degradation, effect. The combined process was tested for AMP degradation, mineralization and inhibition to Vibrio fischeri in wastewater; fast AMP removal was accompanied by low mineralization and incomplete toxicity removal.
7727. 题目: Organic matter affects fiddler crab distribution? Results from field and laboratorial trials
期刊: Estuarine, Coastal and Shelf Science
作者: Fernando Rafael De Grande, Priscila Granado, Fábio Henrique Carretero Sanches, T?nia Marcia Costa
摘要: Fiddler crabs are a key benthic macrofauna group in estuarine environments. Species distribution is determined by relatively distinct zones, based on biotic and abiotic factors. As sediment organic matter is thought to be one of the most important zoning factors of mangrove macrofauna, we tested the effects of organic matter content on the intra-specific distribution of the fiddler crabs Leptuca thayeri and Leptuca uruguayensis. Organic matter content and crab abundance and size were assessed in both species by field observations, while the choice of adult or juvenile L. uruguayensis for high -or low- organic matter was tested in the laboratory. Both species showed no relationship between organic matter and crab abundance or size. Furthermore, L. uruguayensis juveniles or adults did not show any preference for specific organic matter content. Therefore, fiddler crabs intra-specific distribution in mangrove forests is not dependent of the water-land gradient decrease of organic matter.
7728. 题目: Changes in the chemical composition of soil organic matter including water-soluble component during incubation: A case study of coniferous and broadleaf forest soils
作者: Hironori Yoshida, Kazuto Sazawa, Naoya Wada, Noriko Hata, Katsumi Marumo, Masami Fukushima, Hideki Kuramitz
摘要: The objective of this study was to clarify what changes occurred in the amount and chemical properties of the soil organic matter (SOM) and dissolved organic matter (DOM) in the soil following isothermal incubation for 170 days. In this study, the soil samples were collected from coniferous and broadleaf forests in Toyama, Japan. The changes in the amount of carbon dioxide generation, the composition of the organic components of the SOM and its chemical properties during the incubation period were investigated. Likewise, DOM was extracted and examined for changes in chemical properties. For that purpose, pyrolysis-gas chromatography–mass spectrometry using tetramethylammonium hydroxide (TMAH-Py-GC/MS), absorption spectrophotometry, and fluorometry were used. From the amount of CO2 generated during incubation, it was found that 10%–15% of the SOM was mineralized. More CO2 was found to have been generated by the soil of the coniferous forests than by the soil of the broadleaf forests, probably because the former was more strongly affected by temperature changes. The DOM increased during the incubation period by day 55 and then sharply decreased. The absorption and fluorescence spectra showed that the DOM in the soil contained large amounts of humic substances after 97 days of incubation, which comprised organic compounds that did not readily decompose.
7729. 题目: A universal uptake mechanism for cobalt(II) on soil constituents: ferrihydrite, kaolinite, humic acid, and organo-mineral composites
期刊: Geochimica et Cosmochimica Acta
作者: Gemma L. Woodward, Caroline L. Peacock, Alba Otero-Fari?a, Olivia R. Thompson, Andrew P. Brown, Ian T. Burke
摘要: Cobalt is a waste product in many industrial processes and its most common radioactive isotope – 60Co – is a by-product of nuclear reactors. To better understand the mobility and fate of Co in natural and contaminated environments we investigated Co sorption behaviour to the common soil and sediment constituents ferrihydrite, kaolinite, humic acid (HA), and ferrihydrite-HA and kaolinite-HA organo-mineral composites using sorption batch experiments, synchrotron X-ray absorption spectroscopy (EXAFS), and scanning transmission electron microscopy (STEM). We measured the sorption of Co to the end-member mineral and organic phases and the composites as a function of pH, ionic strength and Co concentration, and also for the composites as a function of organic carbon concentration, with composites made containing a wide range of organic carbon contents. We then determined the molecular mechanisms of Co sorption to the end-member phases and the composites, and used this information to develop molecularly constrained thermodynamic surface complexation models to quantify Co sorption. Sorption to the ferrihydrite-HA and kaolinite-HA organo-mineral composites was found to be intermediate to both of the end-member phases, displaying enhanced sorption respective to the mineral end-member phase at mid-low pH. EXAFS analysis shows that there is a universal sorption mechanism accounting for Co sorption to the end-member mineral and organic phases and the organo-mineral composites at mid-high pH, in which Co sorbs to these phases via inner-sphere bidentate binuclear surface complexes. At mid-low pH, sorption to all the phases except ferrihydrite is the result of outer-sphere complexation. Our new molecularly constrained thermodynamic surface complexation models for Co sorption to ferrihydrite, kaolinite, HA, and ferrihydrite-HA and kaolinite-HA organo-mineral composites, show that Co sorption to the composites cannot be modelled assuming linear additivity of Co sorption to the end-member phases.
7730. 题目: Iron cycling and stable Fe isotope fractionation in Antarctic shelf sediments, King George Island
期刊: Geochimica et Cosmochimica Acta
作者: Susann Henkel, Sabine Kasten, Jan Hartmann, Adrián Silva Busso, Michael Staubwasser
摘要: Iron (Fe) fluxes from reducing sediments and subglacial environments are potential sources of bioavailable Fe into the Southern Ocean. Stable Fe isotopes (δ56Fe) are considered a proxy for Fe sources and reaction pathways, but respective data are scarce and Fe cycling in complex natural environments is not understood sufficiently to constrain respective δ56Fe “endmembers” for different types of sediments, environmental conditions, and biogeochemical processes.We present δ56Fe data from pore waters and sequentially extracted sedimentary Fe phases of two contrasting sites in Potter Cove (King George Island, Antarctic Peninsula), a bay that is affected by fast glacier retreat. Sediments close to the glacier front contain more easily reducible Fe oxides and pyrite and show a broader ferruginous zone, compared to sediments close to the ice-free coast, where surficial oxic meltwater streams discharge into the bay. Pyrite in sediments close to the glacier front predominantly derives from eroded bedrock. For the high amount of easily reducible Fe oxides proximal to the glacier we suggest mainly subglacial sources, where Fe liberation from comminuted material beneath the glacier is coupled to biogeochemical weathering processes (likely pyrite oxidation or dissimilatory iron reduction, DIR). Our strongest argument for a subglacial source of the highly reactive Fe pool in sediments close to the glacier front is its predominantly negative δ56Fe signature that remains constant over the whole ferruginous zone. This implies in situ DIR does not significantly alter the stable Fe isotope composition of the accumulated Fe oxides. The nonetheless overall light δ56Fe signature of easily reducible Fe oxides suggests pre-depositional microbial cycling as it occurs in potentially anoxic subglacial environments. The strongest 56Fe-depletion in pore water and most reactive Fe oxides was observed in sediments influenced by oxic meltwater discharge. The respective site showed a condensed redox zonation and a pore water δ56Fe profile typical for in-situ Fe cycling.We demonstrate that the potential of pore water δ56Fe as a proxy for benthic Fe fluxes is not straight-forward due to its large variability in marine shelf sediments at small spatial scales (-2.4‰ at the site proximal to oxic meltwater discharge vs. -0.9‰ at the site proximal to the marine glacier terminus, both at 2 cm sediment depth). The controlling factors are multifold and include the amount and reactivity of reducible Fe oxides and organic matter, the isotopic composition of the primary and secondary ferric substrates, sedimentation rates, and physical reworking (bioturbation, ice scraping). The application of δ56Fe geochemistry may prove valuable in investigating biogeochemical weathering and Fe cycling in subglacial environments. This requires, however (similarly to the use of δ56Fe for the quantification of benthic fluxes), that the spatial and temporal variability the isotopic endmember is known and accounted for. Since geochemical data from subglacial environments is very limited, further studies are needed in order to sufficiently assess Fe cycling and fractionation at glacier beds and the composition of discharges from those areas.
7731. 题目: Seasonal variations of biogeochemical matter export along the Langtang-Narayani river system in central Himalaya
期刊: Geochimica et Cosmochimica Acta
作者: Maya P Bhatt, Jens Hartmann, Miguel F Acevedo
摘要: Weathering and suspended matter fluxes of the Langtang Narayani river system in central Nepal Himalaya have been investigated at 16 stations for one year, based on monthly water sampling in the lower reaches and bi-monthly in higher elevation areas, to determine temporal variations of weathering fluxes along an elevation profile between 169 and 3,989 m asl. Results indicate that the lower reaches are the dominant places of weathering in the system. The sum of major base cation fluxes is 2.9 to 9.2 higher during the monsoon season compared to the pre-monsoon season. Alkalinity and sea-salt corrected sulfate were the dominant anions (97%). The lowest downstream location exports 1,611 tons km-2 yr-1 suspended sediment, 78.56 tons km-2 yr-1 of major cations (Na+K+Mg+Ca), 12.72 tons km-2 yr-1 of silica (4-fold higher than at the middle reaches of the basin), and 1.9×106 mol km-2 yr-1 of dissolved inorganic carbon (8.9-fold higher than at the middle reaches). Nitrogen and phosphorus concentrations are low in general and dissolved organic carbon export is within expected ranges. River water pCO2 values are low in general, with exception of those main stem reaches where tributaries with relevant pyrite oxidation processes, and lower pH, alter the pattern locally. Element ratios suggest seasonal shifts in the weathering flux generation, modulated by the monsoon system. During the monsoon season the most relevant weathering products alkalinity, SO4, Ca and Mg were not diluted, and increased concentrations observed at the lower reaches suggests an enhanced mobilization during this period of the year. Carbonate weathering exceeds silicate weathering along the drainage network and the carbonate- to silicate-cation mol ratio is 3.5 at the outlet. Sulfide oxidation probably enhances weathering rates besides the control of the soil-rock partial pressure of CO2. The ratio of the total alkalinity flux to sea-salt corrected sulfate equivalent flux at the base of the Himalaya at Narayanghat was 5.7. Sea-salt corrected sulfate equivalent export is about the same as the silicate cation-equivalent flux that leaves the system (98%). Therefore, further research on sulfur isotopes might be helpful to support the hypothesis that pyrite oxidation compensates for the idealized CO2-consumption by silicate weathering in the studied area.
7732. 题目: The plant-enhanced bio-cathode: Root exudates and microbial community for nitrogen removal
期刊: Journal of Environmental Sciences
作者: Henan Li, Youpeng Qu, Yan Tian, Yujie Feng
摘要: A plant bio-electrochemical system (PBES) was constructed for organic pollutant removal and power generation. The bio-cathode, composed of granular activated carbon (GAC), stainless wire mesh and a plant species (Triticum aestivum L.), was able to catalyze cathodic reactions without any requirement for aeration or power input. During the 60-day-long operation, an average voltage of 516 mV (1000 Ω) and maximum power density (Pmax) of 0.83 W/m3 were obtained in the PBES. The total nitrogen removal and total organic carbon removal in the PBES were 85% and 97%, respectively. Microbial community analyses indicated that bacteria associated with power generation and organic removal were the predominant species in the bio-cathode, and plant-growth-promoting rhizobacteria were also found in the PBES. The results suggested that the coupling of plants with the GAC cathode may enhance the organic-matter degradation and energy generation from wastewater and therefore provide a new method for bio-cathode design and promote energy efficiency.
7733. 题目: Enhanced sulfate and metal removal by reduced graphene oxide self-assembled Enterococcus avium sulfate-reducing bacteria particles
期刊: Bioresource Technology
作者: Jia Yan, Weizhuo Ye, Zhuoyi Jian, Jiehui Xie, Kengqiang Zhong, Siji Wang, Haoshen Hu, Zixuan Chen, Huijun Wen, Hongguo Zhang
摘要: Graphene oxide (GO) was introduced to Enterococcus avium strain BY7 sulfate-reducing bacteria culture as a carrier, GO was partially reduced by SRB to reduced graphene oxide (rGO). The rGO could further self-assemble Enterococcus avium strain BY7 sulfate-reducing bacteria to form BY-rGO particles. Growth and sulfate reduction activity of strain BY7 was promoted by rGO, which probably due to the protective effect of rGO, and enhanced electron transfer by rGO as electron shuttle. Effects of pH and temperature variance on strain BY-rGO were remarkably weakened, growth and sulfate reduction were observed from pH 2.0 to 12.0, and from 10 to 45 °C, respectively. Metal toxicity to BY7 strain SRB was sharply decreased in BY-rGO particles and heavy metal removal was remarkably accelerated (up to 50%). The immobilization methods established in this study might open a new way for the application of SRBs, especially under extreme environmental conditions.
7734. 题目: Influence of carrier media physical properties on start-up of moving attached growth systems
期刊: Bioresource Technology
作者: Joana Dias, Mel Bellingham, Junaid Hassan, Mark Barrett, Tom Stephenson, Ana Soares
摘要: Five carrier media with different shapes (spherical and cylindrical), sizes, voidage and protected surface areas (112–610 m2/m3) were studied in a pilot scale moving bed biofilm reactor (MBBR). This study aimed at assessing start-up duration using biofilm formation rates. Results indicated that the spherical media required shorter periods to achieve stable biofilm formation rates associated with chemical oxygen demand (COD) (15–17 days), compared to cylindrical high surface area media (23–24 days). Protected surface area presented weaker correlations with the biofilm formation rate for COD (R2 = 0.83) and ammonia removal (R2 = 0.76). However, good correlations were observed with a combination of the media physical factors: dimensionality (Di), voidage (Voi), and hydraulic efficiency (HE) strongly correlated with biofilm formation rates for heterotrophic (R2 = 0.95) and nitrifying bacteria (R2 = 0.92). This study proposes that the media physical properties can contribute to shortening start-up, contributing to improved removal rates and fast commissioning of MBBRs.
7735. 题目: High-silica zeolites for adsorption of organic micro-pollutants in water treatment: A review
期刊: Water Research
作者: Nan Jiang, Ran Shang, Sebastiaan G.J. Heijman, Luuk C. Rietveld
摘要: High-silica zeolites have been found to be effective adsorbents for the removal of organic micro-pollutants (OMPs) from impaired water, including various pharmaceuticals, personal care products, industrial chemicals, etc. In this review, the properties and fundamentals of high-silica zeolites are summarised. Recent research on mechanisms and efficiencies of OMP adsorption by high-silica zeolites are reviewed to assess the potential opportunities and challenges for the application of high-silica zeolites for OMP adsorption in water treatment. It is concluded that the adsorption capacities are well-related to surface hydrophobicity/hydrophilicity and structural features, e.g. micropore volume and pore size of high-silica zeolites, as well as the properties of OMPs. By using high-silica zeolites, the undesired competitive adsorption of background organic matter (BOM) in natural water could potentially be prevented. In addition, oxidative regeneration could be applied on-site to restore the adsorption capacity of zeolites for OMPs and prevent the toxic residues from re-entering the environment.
7736. 题目: Intercropping wheat and maize increases the uptake of phthalic acid esters by plant roots from soils
期刊: Journal of Hazardous Materials
作者: Wenbing Tan, Hanxia Yu, Caihong Huang, Dan Li, Hui Zhang, Xinyu Zhao, Renfei Li, Guoan Wang, Yuan Zhang, Xiaosong He, Beidou Xi
摘要: Whether crop intercropping can affect the uptake of phthalic acid esters (PAEs) by plant roots from soils is unclear. In this study, we compare the PAE uptake by plant roots between the wheat/maize intercropping and the wheat and maize monocropping in a field work. We show that the PAE bioconcentration factors of wheat and maize roots are remarkably higher under wheat/maize intercropping than under monocropping, indicating that intercropping may significantly increase the biouptake of PAEs as compared to monocropping. The wheat/maize intercropping can increase the electron transfer capacity (ETC) of water-extractable organic matter (WEOM) in soils by increasing the abundance of redox-active functional groups in WEOM. The ETC-enhanced WEOM may be an important reason for facilitating the reduction of ferric iron [Fe(III)] minerals to soluble ferrous iron [Fe(II)] by acting as electron shuttle, thus leading to the release of the PAEs originally occluded in Fe(III) minerals into soil pore water. The increased bioavailable PAEs distributed in the soil pore water under wheat/maize intercropping eventually result in the increase in the uptake of PAEs by plant roots from soils. The results can provide insights into the link between the uptake of PAEs by crops and the cropping practices in agricultural ecosystems.
7737. 题目: Fouling resistant 2D boron nitride nanosheet – PES nanofiltration membranes
期刊: Journal of Membrane Science
作者: Ze-Xian Low, Jing Ji, David Blumenstock, Yong-Min Chew, Daniel Wolverson, Davide Mattia
摘要: A novel fouling-resistant nanofiltration mixed-matrix membrane was obtained by the incorporation of 2D boron nitride nanosheets (BNNS) in polyethersulfone (PES). The addition of just 0.05 wt% of BNNS into the PES matrix led to a 4-fold increase in pure water permeance with a 10% decrease in the rejection of the dye Rose Bengal; up to 95% rejection of humic acid and nearly 100% flux recovery over two cycles in cross-flow fouling tests without the need for chemical cleansing. This performance is attributed to the uniform distribution of the BNNS in the PES matrix, observed via Raman mapping, and the surface chemistry and structure of the BNNS, which hydrophilised the polymer matrix and reduced its surface roughness. The low amount of BNNS filler needed to render the mixed-matrix membrane fouling-resistant opens the way to its use in waste-water treatment applications where organic fouling remains a major challenge.
7738. 题目: Biomarker signatures of Upper Cretaceous Latrobe Group hydrocarbon source rocks, Gippsland Basin, Australia: Distribution and palaeoenvironment significance of aliphatic hydrocarbons
期刊: International Journal of Coal Geology
作者: Lian Jiang, Simon C. George
摘要: Upper Cretaceous (Maastrichtian and Campanian) hydrocarbon source rocks from the Latrobe Group, Gippsland Basin (Australia) have been analysed using gas chromatography–mass spectrometry (GC–MS) in order to understand their geochemical characteristics and to reconstruct palaeovegetation and palaeoclimate changes. n-Alkanes ranging from C10 to C37 dominate the aliphatic hydrocarbons in the rock extracts. Both the carbon preference index and the odd-to-even predominance values of n-alkanes are higher than 1.0, suggesting an input from terrigenous higher plants. Low wax indices (mostly < 1.0) and a predominance of C29 over C27 steranes corroborate a major contribution from higher plants. High pristane/phytane (Pr/Ph) ratios (>3.0), a low gammacerane index (<0.3) and the Pr/n-C17 versus Ph/n-C18 cross-plot indicate that the Upper Cretaceous hydrocarbon source rocks were probably deposited in an oxidising environment with fresh water. Thermal maturity parameters such as sterane isomerisation ratios, C31 22S/(22S + 22R) homohopane, C30 αβ/(αβ + βα) hopane and 16(H) β/(α + β) phyllocladane, together with Tmax data and the presence of C27 17β(H)-22,29,30-trisnorhopane (βTm), suggest that most of samples have a relatively low maturity in the early to mid-oil generation window. Angiosperm- and gymnosperm-derived biomarkers, including labdane, pimarane, isopimarane, phyllocladane, abietane, rimuane, ent-beyerane, ent-kaurane, oleanane, 10β(H)-des-A-oleanane, 10β(H)-des-A-lupane, 10β(H)-des-A-ursane, suggest that palaeovegetation during the Upper Cretaceous was characterised by both gymnosperms (e.g. Araucariaceae and Podocarpaceae) and angiosperms (e.g. Nothofagus), but was dominated by gymnosperms. Compared with samples from the Campanian, there was a relatively lesser contribution from angiosperms during the Maastrichtian. This shows that the palaeoclimate was becoming cooler from the Campanian to the Maastrichtian, which is consistent with previous palynology evidence and sea-surface temperature estimates.
7739. 题目: Laser diffraction analysis of aggregate stability and disintegration in forest and grassland soils of northern Minnesota, USA
作者: Chase S. Kasmerchak, Joseph A. Mason, Mengyu Liang
摘要: A method for characterizing aggregate stability with repeated laser diffraction measurements was tested on soils spanning the prairie-forest ecotone in northern Minnesota, USA. These soils formed in similar parent material but display a wide range of upper horizon morphology, organic carbon content, and chemistry, allowing assessment of the method's performance over a wide range of aggregate stability and its utility in identifying factors influencing aggregate behavior. Equations representing fine material release through breakdown of two aggregate populations as first-order processes were fit to experimental data. The best-fit parameters for these equations, and an additional index of persistent water-stable aggregate content, indicated distinct differences in aggregate behavior among the major horizons of Mollisols and Alfisols. Linear models were developed to explore the relationships between these parameters and soil physicochemical characteristics for the dataset as a whole and for subsets corresponding to four zones with different vegetation history, soil orders, and major soil horizons. The relationships identified were relatively weak (R2 = 0.30 to 0.70). The best predictors for the parameters representing early disintegration of less stable aggregates were cation exchange capacity (CEC) and effective CEC (ECEC) for the whole dataset, although organic carbon and nitrogen contents also emerged as predictors for forest and Alfisol subsets. The best predictors for the index of persistent water-stable aggregate content were organic carbon content, base saturation, or exchangeable Ca/Mg ratio, depending on the particular subset and fine material size fraction used in the analysis. The relatively weak explanatory power of organic carbon content as a predictor of aggregate behavior in these experiments was somewhat surprising, given prior work on aggregate stability. Both CEC and ECEC may serve as proxies for the various combinations of organic matter and clay content that influence aggregate stability in these samples, explaining their importance as predictors. It is likely that other factors not examined in this research contributed to aggregate stability, including carbonate content, clay mineralogy, and differing frequency and types of pedoturbation under grassland and forest. The results of this study are relevant to reconstructing the development of texture-contrast profiles as forest invaded grassland over the past 4000 in the study area, as documented by paleoecological research. In particular, loss of organic matter below a thin A horizon may have facilitated initial development of an E horizon in which weak aggregation favored clay eluviation; loss of clay would then have weakened aggregate stability still further. We suggest this new method for assessing aggregate stability can also be applied to research on soil erosion and runoff potential as affected by land use and management.
7740. 题目: Oxidation of benzo[a]pyrene by laccase in soil enhances bound residue formation and reduces disturbance to soil bacterial community composition
期刊: Environmental Pollution
作者: Jun Zeng, Qinghe Zhu, Yucheng Wu, Jun Shan, Rong Ji, Xiangui Lin
摘要: Laccases are capable of rapidly oxidizing benzo[a]pyrene. It is thought that the metabolites with an increase in water solubility caused by the oxidation of benzo[a]pyrene may stimulate the subsequent mineralization. However, to date, there has been no experimental evidence to support this. In this study, the fate of benzo[a]pyrene in soil affected by laccase amendment and the resulting soil bacterial responses were investigated. Laccase amendment promoted benzo[a]pyrene dissipation (15.6%) from soil, accompanied by trace mineralization (<0.58 ± 0.02%) and substantial bound residue formation ( 80%). An increase of 15% in the bound residue fraction was observed by laccase amendment, which mainly resulted from covalent binding of the residues to humin fraction. During the incubation, the abundance of bacterial 16S rRNA and polycyclic aromatic hydrocarbon ring-hydroxylating dioxygenase genes did not change markedly. In contrast, benzo[a]pyrene treated with laccase resulted in a smaller shift in the bacterial community composition, indicating a reduced disturbance to the soil microbial communities. These results here suggest that benzo[a]pyrene contaminated soil can be detoxified by laccase amendment mainly due to the enhanced bound residue formation to soil organic matter via covalent binding.