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28681. 题目: Wetland floodplain flux: temporal and spatial availability of organic matter and dissolved nutrients in an unmodified river
文章编号: N19013018
期刊: Biogeochemistry
作者: Carla L. Atkinson, Brian C. van Ee, YueHan Lu, Wenli Zhong
更新时间: 2019-01-30
摘要: River ecosystem dynamics are strongly regulated by the surrounding watershed. The availability and sources of energy and nutrient resources that drive these systems are controlled by topography, climate, geology, and position in the watershed. Here we examined particulate and dissolved organic matter (POM and DOM, respectively) and nutrient concentrations across an entire watershed during multiple flow regimes in an unregulated, low gradient river with extensive floodplain forests. The objectives of the study were to: (1) determine the influence of watershed position and floodplain connectivity on POM, DOM, and nutrient concentrations; (2) examine the influence of flow variability on POM, DOM, and nutrient concentrations; and (3) develop an empirical rating curve to predict POM, DOM, and nutrient transport and flux. We sampled POM, DOM, and nutrient concentrations (ammonia, nitrate, nitrite and soluble reactive phosphorus) at ten sites across the Sipsey River watershed that varied in their degree of connectivity to the floodplain over a two-year period. Both watershed position and flow regime influenced POM, DOM, and nutrient concentrations. In particular, a large floodplain swamp in the middle of the watershed, the Sipsey Swamp, strongly controlled the relative availability of particulate and dissolved materials in the water. In the headwaters, there was a greater proportion of particulate material in suspension relative to dissolved carbon. While in the downstream reaches, both within and downstream of the Sipsey Swamp, DOC accompanied by greater molecular mass and more aromatic DOM was in greater quantity than particulate materials at high flows. Nutrient concentrations in the stream water tended to decline through the floodplain swamp across all flow conditions and tended to be lower in high flows. We demonstrate that floodplains can disrupt the upstream–downstream continuum by supplying a large quantity of allochthonous organic matter. Using long-term data we estimated the total annual flux of DOC and nitrate to range between 1221–6500 and 24–35 tonnes per year, respectively, between 2007 and 2017 with the highest flux rates occurring during high flow periods. Our study shows the complex dynamics of a natural floodplain river system and generally supports the flood pulse concept by highlighting the importance of wetland complexes and floodplain connectivity on material and nutrient transport. Description of organic matter and nutrient dynamics in natural low gradient rivers is critical to understanding production of organisms, food webs and ecosystem processes in the face of climate and land use changes.

28682. 题目: Mixed heavy metals removal from wastewater by discarded mushroom-stick biochar: adsorption properties and mechanisms
文章编号: N19013017
期刊: Environmental Science: Processes Impacts
作者: Xinhua Wang, Xin Li, Guangqing Liu, Yufei He, Chang Chen, Xiaoying Liu, Gang Li, Yiqin Gu, Yuqing Zhao
更新时间: 2019-01-30
摘要: Abstract The physicochemical, morphology properties and the sorption capacities of discarded mushroom-stick biochar (DMB) prepared under different pyrolysis temperatures from 300 °C to 800 °C were explored. Results showed that the yield and surface oxygen-containing group of DMB prepared at 300 °C (DMB3) were higher than that of DMB prepared at higher pyrolysis temperature (DMB5 and DMB8), while the DMB prepared at 800 °C (DMB8) had higher pH, mineral elements, ash content, aromaticity, and polarity. Therefore, the heavy metal adsorption capacity of DMB3 was higher than DMB5, while the maximal sorption capacities of Pb2+, Cu2+, Cd2+, and Ni2+ (21.0, 18.8, 11.2, and 9.8 mg•g−1) were obtained by DMB8. Adsorption kinetics and sorption isotherms data were fitted more well by pseudo second order and Langmuir models, thereby indicating that the heavy metal adsorption by DMB was monolayer and rapid adsorption. Based on the contribution percentage parameters of diverse heavy metal sorption mechanisms, mineral precipitation and ion exchange were the two dominant mechanisms of heavy metal adsorption by DMB. This study provided a promising way not only to recycle the discarded mushroom-sticks into feasible heavy metal adsorbents, but also for potential utilization of agriculture waste.

28683. 题目: Community transcriptomics reveals drainage effects on paddy soil microbiome across all three domains of life
文章编号: N19013016
期刊: Soil Biology and Biochemistry
作者: Rehab Z. Abdallah, Carl-Eric Wegner, Werner Liesack
更新时间: 2019-01-30
摘要: Drainage is an important mitigation strategy to reduce methane emission from rice paddies. Here, we investigated how drainage shapes structure and functioning of the paddy soil microbial community. Soil microcosms were pre-incubated for 28 days under flooded conditions followed by nine days' drainage. Upon sampling, metatranscriptome libraries were generated from flooded and drained soils. With drainage, oxygen concentration increased from suboxic (1.6 μmol/l) to near-atmospheric (240 μmol/l) levels. Concurrently, water potential decreased to −0.87 MPa (corresponding to 11% soil moisture content). Drainage did not affect the absolute (RT-qPCR) SSU rRNA abundance of Bacteria and Archaea, but changed significantly their community composition. Firmicutes (Clostridiaceae, Ruminococcaceae, and Lachnospiraceae) decreased in relative abundance, while Actinobacteria (Nocardioidaceae) and Proteobacteria (Comamonadaceae) increased. These taxon-specific dynamics were observed on rRNA and mRNA levels. Methanogen SSU rRNA was stable, but methanogen mRNA significantly decreased. This coincided with complete inhibition of the methane production potential in drained soil. Among Eukarya, protists and Amoebozoa thrived in flooded soil, while Fungi proliferated with drainage. In particular, Pezizomycotina (Ascomycota) and Agaricomycotina (Basidiomycota) were the most abundant fungal groups in dry soil. Taking community-wide mRNA expression as a proxy, the overall microbial activity was not severely affected by drainage. The proportion of mRNA in total RNA increased from 1.7% to 2%. In particular, the abundance of mRNA related to transcription and translation significantly increased. Correspondingly, the bacterial SSU rRNA transcript/gene ratio increased 12-fold with drainage, suggesting the development of a metabolically highly active microbial community well adapted to oxic and dry soil conditions. This community showed an increased transcription of genes involved in the degradation of lignin, peptidoglycan, and storage molecules such as glycogen. Under flooded conditions, the microbial community expressed a higher level of glycoside hydrolase transcripts involved in cellulose and chitin degradation.

28684. 题目: Organic degradation and extracellular products of pure oxygen aerated activated sludge under different F/M conditions
文章编号: N19013015
期刊: Bioresource Technology
作者: Hong-Ling Zhang, Wei-Li Jiang, Rong Liu, Ying Zhou, Yong Zhang
更新时间: 2019-01-30
摘要: This study aimed to investigate the effect of food to microorganisms rate (F/M) on organic removal, extracellular polymeric substances (EPS) and soluble microbial products (SMP) of the pure oxygen aerated activated sludge running in batch mode. The F/M rates were controlled by adjusting the MLSS concentrations (2000, 5000, 8000 mg/L) and/or the initial TOC concentrations (100, 500 mg/L). Results showed that at high F/M rate (0.25 kg TOC/kg MLSS), the substrate degradation rate in the oxygen aerated reactor could reach 1.347 mg TOC/(L•min)), much higher than that in the air aerated reactor (0.640 mg TOC/(L•min)). The SMP concentrations with oxygen aeration were also higher than those with air aeration under high F/M conditions. The total EPS contents in the pure oxygen aerated sludge were significantly lower regardless of the different F/M rates. High F/M condition would lead to more amount of polysaccharides synthesis rather than proteins synthesis in EPS.

28685. 题目: Variations in trace metal concentrations and Sr, Nd isotopic compositions in sediments from two contrasting settings in the Eastern Arabian Shelf: Implications for provenance and paleoclimate reconstruction
文章编号: N19013014
期刊: Chemical Geology
作者: Shiba Shankar Acharya, Ramananda Chakrabarti
更新时间: 2019-01-30
摘要: Major and trace elements concentrations as well as Nd and Sr isotopic ratios were measured in sediments from two gravity cores (GC17 and GC19) deposited in the high-sediment flux regime of the Eastern Arabian Shelf (EAS). The core-sampling locations are close to the mouths of the geochemically and isotopically well-characterized Rivers Mandovi and Zuari and are overlain by water columns of contrasting redox conditions. Given the available knowledge of bottom water oxygen concentrations in the studied locations, the compositions of the Mandovi and Zuari sediments as well as the lithology of the drainage basin, the goal of this study was to test the efficacy of different paleo-redox proxies and provenance indicators in a high-sediment flux regime of the ocean.The variations of immobile elements like Al, Ti, Th, and Zr in the studied samples suggest lack of sediment reworking and sorting. Provenance proxies such as Th/Co, La/Sc ratios and variations in La-Th-Sc concentrations suggests a dominantly silicic source rock of granitic to granodioritic composition for these sediments, which is consistent with the dominant lithology of the drainage basins of the Mandovi and Zuari Rivers. Minor contributions from a mafic source (basalt or metabasalt) cannot be ruled out. The chemical index of alteration (CIA) and plagioclase index of alteration (PIA) values of the samples suggest low to moderate weathering of the source rocks. While the Sr isotopic compositions of the GC17 and GC19 sediments overlap with that of the gneissic basement rocks from the Mandovi and Zuari drainage basins, the ε_Nd(0) of the sediments (average −13.72) show significantly more radiogenic values compared to the gneissic basement rocks (average −36). This difference in the Nd isotopic compositions is explained by early selective weathering and removal of rock-forming minerals like plagioclase in the source rocks which results in the supply of radiogenic Nd isotopic composition bearing sediments to the ocean. This argument is consistent with the overlapping ε_Nd(0) of the GC17 and GC19 sediments and suspended particulate matter (SPM) of the Mandovi and Zuari Rivers. Although, the Nd isotopic compositions overlap, the less radiogenic Sr isotopic compositions of the GC17 and GC19 sediments compared to the SPM of the Mandovi and Zuari Rivers suggests the influence of organic matter, formation of authigenic clay and carbonates, as well as the contribution of Sr from submarine groundwater discharge.Trace metal concentrations and ratios were measured in the bulk sediments as well as in the leached authigenic and residual detrital-rich fractions of selected samples. For the GC19 sediments overlain by oxygenated waters, these geochemical proxies correctly infer their deposition under oxic conditions. In contrast, most of these proxies, barring those involving U and Mo, erroneously infer oxic depositional conditions for the GC17 sediments which are overlain by an oxygen minimum zone (OMZ) of the eastern Arabian Sea. We believe that the high sedimentation rate and large terrigenous flux possibly prohibits the equilibration of some of these trace metals in the sediments with the ambient seawater. Our study suggests that U and Mo-based proxies for inferring paleo-redox conditions are robust even under high sedimentation conditions. Overall, this study provides useful insights into the behaviour of redox-sensitive elements and provenance indicators in a continental margin setting impinged by an OMZ.

28686. 题目: Changes in heavy metal mobility and availability in contaminated wet-land soil remediated using lignin-based poly(acrylic acid)
文章编号: N19013013
期刊: Journal of Hazardous Materials
作者: Tianqi Zhao, Kun Zhang, Junwei Chen, Xiaobai Shi, Xu Li, Yanli Ma, Guizhen Fang, Shiyu Xu
更新时间: 2019-01-30
摘要: To mitigate the serious ecological problems and risks to human health that are posed by heavy metals in the soil, it is important to enhance the efficiency of heavy metal extraction by washing contaminated soil using chemical methods. Secondary pollution of soil by chemical chelating agents has, however, brought a new threat to the environment. Here, we describe a biodegradable LBPAA (lignin based poly(acrylic acid)) composite that was designed as a chelating agent to wash soil contaminated with Cu²⁺, Zn²⁺, Cd²⁺ and Pb²⁺ ions. Extraction and ion transfer of heavy metal ions by the LBPAA composite improved the remediation rate of contaminated soil during water leaching. After washing five times, the LBPAA-assisted elution process reduced the amount of Cu²⁺, Zn²⁺, Cd²⁺ and Pb²⁺ ions in contaminated soil to 22.57%, 52.60%, 13.63% and 17.95%, respectively. These values are 2.39-fold, 5.04-fold, 5.04-fold and 1.31-fold, respectively, better than elution with deionized water. Additionally, LBPAA is able to sequester Cd²⁺ and Pb²⁺ ions from the contaminated soil and transfer them to the eluent. In summary, this work provides a safe, environmentally friendly and sustainable remediation strategy for heavy metal-contaminated soil and demonstrates a new application for lignin in the field of soil remediation.
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28687. 题目: Biochar Combined with Vermicompost Increases Crop Production While Reducing Ammonia and Nitrous Oxide Emissions from a Paddy Soil
文章编号: N19013012
期刊: Pedosphere
作者: Di WU, Yanfang FENG, Lihong XUE, Manqiang LIU, Bei YANG, Feng HU, Linzhang YANG
更新时间: 2019-01-30
摘要: Organic amendments such as vermicompost and biochar have been reported to enhance soil fertility and crop productivity. However, whether the co-application of both amendments has synergistic effects or whether such benefits are accompanied by the risk of gaseous nitrogen (N) loss in an agroecosystem remains unknown. A soil column experiment with a fully factorial design was conducted using three levels of vermicompost (no dose, low dose (1%, weight:weight), and high dose (3%, weight:weight)) without or with biochar (1%, weight:weight) to investigate their effects on rice growth and gaseous N loss across the crop growing season. Our results demonstrated that synergistic interactions existed between vermicompost and biochar in promoting crop yield. Compared with biochar amendment alone, biochar combined with vermicompost significantly (P < 0.01) increased rice yield by 26.5%–35.3%. However, high dose of vermicompost significantly (P < 0.01) increased the cumulative ammonia (NH₃) and nitrous oxide (N₂O) emissions. In the presence of vermicompost, the incorporation of biochar amendment significantly (P < 0.01) decreased the cumulative N₂O emission by 14.1%–18.6%. The lowest emission factor value of NH₃ and N₂O was achieved using biochar in combination with low dose of vermicompost. This study revealed that the combination of biochar and moderate dose of vermicompost offers a novel approach to promote crop productivity while reducing the environmental risk.

28688. 题目: A comparative study of ferrous, ferric and ferrate pretreatment for ceramic membrane fouling alleviation in reclaimed water treatment
文章编号: N19013011
期刊: Separation and Purification Technology
作者: Jing Liu, Zhenghua Zhang, Shengyin Tang, Ting Wang, Xihui Zhang
更新时间: 2019-01-30
摘要: Coagulation-membrane filtration hybrid process has been widely applied in water treatment to improve water quality and alleviate membrane fouling. Herein, we systematically investigated the comparable effect of ferrate, ferrous and ferric pretreatment on fouling alleviation of ceramic membrane in reclaimed water treatment. Our results showed that the pretreatment of ferric, ferrous and ferrate remarkably alleviated membrane fouling with the fouling alleviation performance following the order: ferrate > ferrous > ferric > control. The t_crit (subcritical fouling time) after which the fouling rate (dTMP/dt) became much more severe was remarkably extended from 0 (control) to 432 (ferric), 576 (ferrous) and 888 h (ferrate), respectively. Meanwhile, hydraulically reversible fouling resistance had the greatest contribution (58.3%) to the overall fouling resistance in the control case, however, hydraulically irreversible membrane fouling caused by inorganics (R_ir-citrate) became more severe in long-term operation with the contribution of R_ir-citrate to the total fouling resistance of 40.7%, 46.3% and 50.3% in the cases with ferric, ferrous and ferrate pretreatment, respectively. Moreover, the redundancy analysis results showed that the alleviated membrane fouling was principally owing to the sharp reduction of organic matters and the significant increase of particle size and particle concentration in influent. Compared with ferric and ferrous, ferrate had the best fouling alleviation performance, which was mainly due to its dual functions of chemical oxidation (including ·OH, Fe(V) and Fe(IV)) and coagulation (ferric oxyhydroxides).

28689. 题目: Removal of the drug procaine from acidic aqueous solutions using a flow reactor with a boron-doped diamond anode
文章编号: N19013010
期刊: Separation and Purification Technology
作者: Nathalia M.P. Queiroz, Ignasi Sirés, Carmem L.P.S. Zanta, Josealdo Tonholo, Enric Brillas
更新时间: 2019-01-30
摘要: This article reports the electrochemical advanced oxidation treatment of 2.5 L of acidic aqueous solutions with 0.320 mM of the drug procaine hydrochloride in 0.050 M Na₂SO₄ using a pre-pilot flow plant. This was equipped with a cell, containing a boron-doped diamond (BDD) anode and an air-diffusion cathode for H₂O₂ generation, which was connected to an annular photoreactor with a 160 W UVA lamp for the study of photoelectro-Fenton (PEF) process. Poor degradation and mineralization was attained by electrochemical oxidation with electrogenerated H₂O₂ due to the limited attack of both, hydroxyl radical (^•OH) formed at the BDD surface from water oxidation and H₂O₂ on organic matter. The electro-Fenton process became more effective thanks to the simultaneous oxidation with ^•OH formed from Fenton’s reaction in the presence of Fe²⁺. The most powerful process was PEF because of the additional photolysis of photoactive intermediates by UVA radiation. This method allowed achieving 91% mineralization after 360 min of electrolysis at 33.3 mA cm^-2. The effect of current density and drug concentration on PEF performance was examined. The mineralization current efficiency and energy consumption were determined for each treatment. Two nitroderivatives were identified by gas chromatography-mass spectrometry. The quantification of generated carboxylic acids revealed that the final solution in PEF was composed of a mixture of acetic and formic acids.
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28690. 题目: Magnetic nitrogen-doped sludge-derived biochar catalysts for persulfate activation: Internal electron transfer mechanism
文章编号: N19013009
期刊: Chemical Engineering Journal
作者: Jiangfang Yu, Lin Tang, Ya Pang, Guangming Zeng, Jiajia Wang, Yaocheng Deng, Yani Liu, Haopeng Feng, Song Chen, Xiaoya Ren
更新时间: 2019-01-30
摘要: Persulfate-based advanced oxidation process is a powerful countermeasure for water remediation, where effective and low-cost catalysts are still needed. Herein, a one-pot synthetic method for magnetic nitrogen-doped sludge biochar (MS-biochar) was presented, which exhibited better catalytic property with PDS for tetracycline degradation than typical graphitic carbon (graphite powder, graphene oxide and multiwalled carbon nanotubes) and two other types biochars. EDAX manifested the uniform dispersion of elements in MS-biochar. Similar to “top-down”, a research thought from whole to part of MS-biochar for contribution measurement was presented, where acid-soluble substance (ASS) was the most important contributor for MS-400/600 while carbon matrix (CM) was dominant for MS-800. Quenching and EPR demonstrated a free-radicals pathway in MS-biochar/PDS, where ASS mainly assumed to be effective for SO₄^•- and CM was primarily committed to •OH generation. EDAX, XPS and Raman studies proved three kinds of catalytic sites, namely the iron compounds, doped nitrogen and graphitic carbon. And their activating mechanism were discussed where one internal electron migration path (from sp³ to nanocrystalline sp² carbon) has been first proposed. Reusability, metal leaching detection and pharmaceutical wastewater application indicated the potential of MS-biochar. This work not only presents a potential resource-based disposal of sewage sludge, a novel research thought from whole to part for materials performance measurement, but also provides guidance for carbon materials’ design for persulfate activation, especially for sp² and sp³ co-hybridized carbons.

28691. 题目: Photodegradation of novel brominated flame retardants (NBFRs) in a liquid system: Kinetics and photoproducts
文章编号: N19013008
期刊: Chemical Engineering Journal
作者: Siyuan Ling, Kai Huang, Muhammad Tariq, Yawen Wang, Xiao Chen, Wei Zhang, Kuangfei Lin, Bingsheng Zhou
更新时间: 2019-01-30
摘要: The photolysis of four typical NBFRs decabromodiphenyl ethane (DBDPE), bis(2-ethylhexyl) tetrabromophthalate (TBPH), pentabromotoluene (PBT) and hexabromobenzene (HBB) were first explored under different sources of light, two temperatures, organic solvents and the presence of humic substance (HS). Degradation could be described by pseudo-first-order kinetic model. Under different irradiation sources, the degradation rates were in order of UVC (0.0616–0.137 min⁻¹) > UVB (0.0348–0.0810 min⁻¹) > sunlight (0.0102–0.0370 min⁻¹) > UVA (almost no degradation). Under UVB irradiation, the half-life of NBFRs was the lowest in tetrahydrofuran (6.16–22.77 min), and the longest (93.42–>120 min) in acetone, indicating that organic solvents greatly affected the degradation kinetics. HS could influence the degradation, and DBDPE or TBPH respectively declined 13.92–30.68% and 12.17–59.41% at 240 min, while the degradation of PBT and HBB were highly inhibited. TBPH photolysis was affected by humic acid (HA) or fulvic acid (FA) concentration, but DBDPE degradation barely showed significant difference (p < 0.05) in the presence of 1 and 10 mg L⁻¹ of HA. Photolytic products of the four NBFRs were identified by GC-NCI/EI-MS, indicating that the photodegradation process was mainly stepwise debromination from high- down to low-bromine-substituted NBFRs. 2,4,6-triBT and 2,4,5-triBT were identified as products of PBT. PBB, 1,2,4,5-tetraBB, 1,2,4-triBB, 1,3,5-triBB and 1,3/1,2-diBB were identified as products of HBB. Our observations could provide a few insights into the removal of NBFRs in a liquid environment.
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28692. 题目: Molecular weight-dependent adsorption fractionation of natural organic matter on ferrihydrite colloids in aquatic environment
文章编号: N19013007
期刊: Chemical Engineering Journal
作者: Huacheng Xu, Li Ji, Ming Kong, Helong Jiang, Jie Chen
更新时间: 2019-01-30
摘要: Natural organic matter (NOM), a heterogeneous mixture with various organic components and continuous molecular weight (MW) distribution, is omnipresent in natural waters. To date, understanding of the MW-dependent adsorption fractionation of NOM samples on colloids is limited due to the lack of NOM fractionation and characterization methods. In this study, the ultrafiltration technique was applied to fractionate the bulk NOM samples into low MW (LMW-, <1 kDa) and high MW (HMW-, 1 kDa∼0.45 μm) fractions, whose adsorption behaviors on ferrihydrite colloids were comparatively examined via using total organic carbon, chromophoric, fluorescent emission-excitation matrix-parallel factor (EEM–PARAFAC), and two dimension FTIR correlation spectroscopy (2D–FITR–COS). The adsorption behaviors of all samples can be reasonably explained by Langmuir and Frendlich isotherm models, and the HMW-NOM exhibited higher adsorption capacities and affinities (4.71 mg-C/g) than the bulk (3.88 mg-C/g) and LMW- (2.44 mg-C/g) counterparts. Irrespective of MWs, the non-aromatic moieties were preferentially adsorbed by ferrihydrites, causing an enhanced aromaticity for the residual solutions. Two humic-like and one protein-like component were identified by EEM–PARAFAC, and a increase and decrease trend of K_a (adsorption affinity) were observed for humic- and protein-like components, respectively, in the order of LMW-, bulk, and HMW-NOM, showing obvious MW- and component-dependent adsorption fractionation of NOM on ferrihydrite colloids. 2D–FTIR–COS provided further information that, with increasing site limitation, the C–O in carbohydrate was adsorbed prior to the amide I in proteins, which testified the MW-dependent adsorption fractionation of NOM samples and accounted for the enhanced aromaticity in the residual solutions. This study highlighted the importance of MWs in NOM adsorption, which can enhance our understanding of the biogeochemical cycles of colloids and contaminants in aquatic environments.
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28693. 题目: Scaling-up a heterogeneous H₂O₂/TiO₂/solar-radiation system using the Damköhler number
文章编号: N19013006
期刊: Chemical Engineering Journal
作者: Héctor L. Otálvaro-Marín, Francy González-Caicedo, Augusto Arce-Sarria, Miguel Angel Mueses, John C. Crittenden, Fiderman Machuca-Martinez
更新时间: 2019-01-30
摘要: A falling film photocatalytic solar reactor (FFR) and a tubular reactor with compound parabolic collectors (CPCR) were modeled. An empirical reaction mechanism was proposed for the heterogeneous photocatalytic degradation of organic contaminants using TiO_2, and H₂O₂. An analytical kinetic rate was deducted from the mechanism in order to describe the change of H₂O₂ concentration and the rate of destruction of total organic carbon (TOC). The profiles of the absorption rate of photons in the heterogeneous medium were estimated by using the absorption-scattering radiation six-flux model (SFM). A dimensionless number that we named Damköhler of a photocatalytic reactor was proposed (Daph). Finally, the modeling was validated against experimental data for the TOC destruction obtained from the mineralization of dicloxacillin (DCX) and 4-chlorophenol (4-CP), which we considered as model pollutants.The modeling fit the experimental data with a standard deviation of 1.30 ppm. The kinetic constants were independent of the geometry, this is because the mass transport, radiant energy, and an intrinsic kinetic expression were taken into account. Therefore, the constants can be used in the design and simulation of new geometries. Under the best-tested conditions, 58.7 mol of organic carbon were converted to CO₂ per each 100 mol of photons absorbed (quantum yield near to 0.5). Also, Daph is expressed mathematically by the contributions of the catalyst, the radiant field, the substrate and the mean residence time within the reactor. The latter is key to the large-scale sizing of these photocatalytic solar reactors for industrial applications. Then, Daph indicates how the designs of new reactors can be improved

28694. 题目: Formation of CX₃R-type disinfection by-products during the chlorination of protein: The effect of enzymolysis
文章编号: N19013005
期刊: Chemical Engineering Journal
作者: Chao Fang, Jianglin Hu, Wenhai Chu, Shunke Ding, Tiantao Zhao, Xiaoyan Lu, Hongying Zhao, Daqiang Yin, Naiyun Gao
更新时间: 2019-01-30
摘要: It is commonly acknowledged that proteins, comprising a large portion of dissolved organic nitrogen pool, are important precursors of disinfection by-products (DBPs). Moreover, proteins can also undergo degradation (e.g. enzymolysis) in aquatic environment or during biological treatment processes. In this study, a well-characterized protein, bovine serum albumin (BSA) was used as model compound to investigate the effect of enzymolysis on the formation of four classes of CX₃R-type DBPs (i.e. trihalomethanes, haloacetaldehydes, haloacetonitriles, and haloacetamides) during chlorination. After enzymolysis, the three-dimension structure of BSA was destroyed, increasing the accessibility of inside amino acids to chlorine, thus enzyme-hydrolysed BSA exhibited higher chlorine demand and higher formation of total organic halogen (TOX) than un-hydrolysed BSA. Generally, enzyme-hydrolysed BSA produced more CX₃R-type DBPs, which is due to the facilitation of fragmentation of BSA by enzymolysis. In the presence of bromide, enzymolysis promoted the formation of TOX to a greater extent than in the absence of bromide. The effect of enzymolysis on pre-oxidation efficiency in the control of CX₃R-type DBPs was also investigated. It was found that the reduction in CX₃R-type DBP formation from chlorinated enzyme-hydrolysed BSA was more significant than that from chlorinated un-hydrolysed BSA, but the former still exhibited higher calculated cytotoxicity than the latter, indicating the removal of CX₃R-type DBP precursors was indirectly offset by the effect of enzymolysis. This study provides insights into the effect of the structural transformation of protein during water treatment processes on CX₃R-type DBP formation.
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28695. 题目: Degradation of haloacetonitriles with UV/peroxymonosulfate process: Degradation pathway and the role of hydroxyl radicals
文章编号: N19013004
期刊: Chemical Engineering Journal
作者: Xing Zhang, Jilun Yao, Zhiwei Zhao, Jie Liu
更新时间: 2019-01-30
摘要: Haloacetonitriles (HANs), a specie of new emerging halogenated nitrogenous disinfection by-products (N-DBPs) including trichloroacetonitrile (TCAN), dichloroacetonitrile (DCAN), monochloroacetonitrile (MCAN) and dibromoacetonitrile (DBAN), were more cytotoxic and genotoxic than the conventional DBPs. In this study, kinetics and mechanisms in the oxidization of HANs by UV/peroxymonosulfate (PMS) process were investigated. The degradation of chloroacetonitriles (CANs) in UV/PMS process was more remarkable than UV alone, PMS alone and UV/H₂O₂ process. And the order of the rates of degradation of HANs was followed: TCAN > DCAN > MCAN, while DBAN was remarkably degraded by UV alone. The degradation of DCAN was accelerated by humic acid and Cl⁻, while suppressed by bicarbonate. Scavenging experiments showed that hydroxyl radical (^radOH) was the predominant species in the reaction. According to the gas chromatography/mass spectrometer (GC/MS) analysis, the breakage of CCl bond was the dominant pathways in degradation of CANs.
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28696. 题目: CO₂-mediated Chicken Manure Biochar Manipulation for Biodiesel Production
文章编号: N19013003
期刊: Environmental Research
作者: Jong-Min Jung, Jeong-Ik Oh, Young-Kwon Park, Jechan Lee, Eilhann E. Kwon
更新时间: 2019-01-30
摘要: This study employs chicken manure as a feedstock to produce different forms of energy to abate environmental burdens. To achieve ultimate carbon management, the possible utilization of CO₂ during pyrolysis of chicken manure was fundamentally investigated. The roles of CO₂ in pyrolysis of chicken manure include enhanced thermal cracking and shifting of the carbon distribution via reaction between volatile organic compounds and CO₂. The identified roles induced by CO₂ were catalytically enhanced because of the inorganic content in the feedstock. The morphology of biochar created from the chicken manure pyrolysis was significantly affected by CO₂. For example, a well-developed pore structure was observed in the biochar developed under a CO₂ environment; this biochar was used as an effective porous material for biodiesel synthesis.

28697. 题目: Effect of water depth on the TEX₈₆ proxy in volcanic lakes of northeastern China
文章编号: N19013002
期刊: Organic Geochemistry
作者: Yuan Yao, Jiaju Zhao, Thorsten Bauersachs, Yongsong Huang
更新时间: 2019-01-30
摘要: The TEX₈₆ index, based on the distribution of isoprenoid glycerol dialkyl glycerol tetraethers (iGDGTs), has been widely applied for reconstructing past sea surface temperature (SST). However, its successful application in lacustrine environments has been limited to certain large lakes in which aquatic Thaumarchaeota are thought be the dominant iGDGT producers. In small lakes, multiple factors, such as iGDGTs from soil and non-thaumarchaeotal sources, could complicate the use of TEX₈₆ as a temperature proxy (Powers et al., 2010). Here we investigate iGDGTs from surface sediments and suspended particulate matter (SPM) in a series of small volcanic lakes (areas: ∼ 0.1 to 8.2 km²) from three main volcanic fields of northeastern China. The iGDGT distribution patterns from surface sediments of these lakes differ significantly from those of surrounding soils, global marine sediments, as well as cultured Group I.1a and Group I.1b Thaumarchaeota, suggesting a substantial contribution of autochthonous non-thaumarchaeotal sources. Interestingly, however, the correlation between TEX₈₆ values in the SPM samples and in situ water temperatures remain strong and display temperature sensitivity similar to previously published linear calibrations from global marine and lake sediments. Our results suggest that the in situ TEX₈₆-temperature relationship is little affected by the non-thaumarchaeotal iGDGT sources in these lakes. However, the TEX₈₆-inferred temperatures from surface sediments show increasingly colder offsets relative to air temperatures with increasing lake depth, which can be explained by the observed increase in iGDGTs production and decrease in water temperatures in water column as depth increases. Our results thus suggest that TEX₈₆ values in the sediments of these volcanic lakes are affected by both temperature and lake depth, and when temperature can be constrained independently or remains constant over a given period of time, have potential application as a lake level proxy in deep volcanic lakes.

28698. 题目: A new strategy for assessing the binding microenvironments in intact soil microaggregates
文章编号: N19013001
期刊: Soil and Tillage Research
作者: Jian Xiao, Yong-Li Wen, Sen Dou, Benjamin C. Bostick, Xin-Hua He, Wei Ran, Guang-Hui Yu, Qi-Rong Shen
更新时间: 2019-01-30
摘要: Adsorption to soil minerals and occlusion within soil aggregates are two critical mechanisms to shield soil organic carbon (SOC) from microbial decomposition. Here, we combined the synchrotron radiation based Fourier transform infrared (SR-FTIR) spectroscopy, synchrotron radiation based micro X-ray fluorescence microscopy (μ-XRF) and two-dimensional correlation spectroscopy (2DCOS) analysis to in situ visualize the interiors of intact microaggregates from a typical Ferralic Cambisol in China, which had endured 25-year organic fertilization. Results showed that the spatial distribution and correlation between clay clusters and biopolymers were heterogeneous and significant, and also demonstrated that clay clusters were associated as nuclei with the potential of binding carbon at the submicron scale. Furthermore, the combination of SR-FTIR mapping and 2DCOS analysis could explore the strategy of identifying overlapped spectra and quantifying the sequestration reactivity for the first time. Specifically, carbon retention correlated as the binding sequence orders: 3630 cm⁻¹ > 3610 cm^-1, 985 cm^-1 > 898 cm^-1, indicating that Fe/Al oxyhydroxides and phyllosilicates could regulate the organic matter sequestration without the influence of spatial perturbations. Together, we conclude a combined methodology to assess the heterogeneous binding microenvironments between the mineral assemblages and biopolymers, which could also contribute to understand the process of carbon sequestration interrestrial ecosystems.

28699. 题目: Multi-proxy evidence for paleoclimate evolution performed on a paleolake sediment core in the East Asian Monsoon Region
文章编号: N19012903
期刊: Environmental Earth Sciences
作者: Longjuan Cheng, Wei Ye
更新时间: 2019-01-29
摘要: A sediment succession from a paleolake in the Hangjiahu Plain, Southeast China, covering the period 11.4–5.0 cal ka BP was studied using grain size, total organic carbon (TOC), organic carbon isotope (δ¹³C_org), C/N ratio, pollen, carbonate and its carbon and oxygen isotopes (δ¹⁸O_carb and δ¹³C_carb) analysis to reconstruct climate changes. The methods of redundancy analysis (RDA) ordination and correlation analysis (CA) were employed to quantify the influence of geochemical indexes on the biological index (the pollen) and to explain the environmental significance of each proxy more scientifically and accurately, so as to provide more reliable indication for the reconstruction of the paleoclimate. The reconstruction, supported by the AMS ¹⁴C age modelling, indicates climatic evolution during the Early–Middle Holocene period, at least, experienced four stages: (1) a period of gradual warm and humid during the early Holocene (11.4–8.7 cal ka BP). (2) A middle continuous cold–dry stage (8.7–8.0 cal ka BP), precipitation and temperature declined revealed by the proxies. (3) 8.0–6.6 cal ka BP, which was the wettest and warmest stages in the climate change sequence, precipitation, and temperature increased markedly, and this stage was consistent with the Holocene Climate Optimum. (4) A cold–dry period during the middle Holocene (6.6–5.0 cal ka BP), and particularly worth mentioning was that a large number of Oryza pollens were found which indicated the rice-based agriculture developed. In particular, the Liangzhu Culture in this region appeared at this time.

28700. 题目: Effects of early diagenesis on Mg isotopes in dolomite: the roles of Mn(IV)-reduction and recrystallization
文章编号: N19012902
期刊: Geochimica et Cosmochimica Acta
作者: Weiqiang Li, Or M. Bialik, Xiaomin Wang, Tao Yang, Zhongya Hu, Qingyu Huang, Shugao Zhao, Nicolas D. Waldmann
更新时间: 2019-01-29
摘要: Sedimentary dolomite plays an important role in global Mg cycling, and Mg isotopes in massive dolostones may be used to infer secular changes in seawater chemistry through geological history. However, sedimentary dolomite is generally regarded as a diagenetic product, and many details about the effects of early diagenesis on the Mg isotope composition of dolomite remain unclear. The mid-Cretaceous (Albian) Soreq and Givat Ye’arim formations near Jerusalem, Israel, contain exceptionally well-preserved massive dolostones, which provide an ideal opportunity to investigate the Mg isotope responses to early diagenesis. Dolomite samples from this section show large variations in δ¹³C values and Mn contents that are negatively correlated, reflecting degradation of organic matter and mineralization of organic carbon in the Mn(IV) reduction zone within soft sediment during dolomite formation. This is a rare example of a clear link between Mn(IV) reduction and dolomite precipitation based on geochemical evidence in the rock record. The dolomite samples also exhibit large variations in d(104) values and the degree of cation ordering. The latter is negatively correlated with Sr contents, implying that variable degrees of dolomite recrystallization occurred during diagenesis. δ²⁶Mg values of >50 dolomite samples from this section vary from –2.28‰ to –1.78‰, but do not correlate with indicators of organic matter degradation (δ¹³C values and Mn contents) or dolomite recrystallization (e.g., Sr contents), suggesting that Mg isotopes behave conservatively after initial dolomite (or proto-dolomite) precipitation during the very early stages of diagenesis. We propose that the Mg isotope composition of dolomite formed due to Mn(IV) reduction is buffered by seawater due to the shallowness of the Mn(IV) reduction zone in platform sediments, which is different from the dolomitization associated with bacterial sulfate reduction or methanogenesis, where Mg supply can be diffusion-limited. Furthermore, Mg isotopes in dolomite are robust to resetting by recrystallization during burial. Magnesium isotope compositions of platform dolomite that show variable and negatively correlated δ¹³C values and Mn contents can, therefore, be considered robust archives for reconstructing paleo-seawater Mg isotope compositions. The variation in δ²⁶Mg values of the dolostones in the Soreq and Givat Ye’arim formations is interpreted to reflect Rayleigh fractionation in response to dolomitization in a restricted water body. Therefore, the lowest δ²⁶Mg value is considered to be the Mg isotope composition of dolomite that was in equilibrium with coeval seawater in the open ocean, and thus the δ²⁶Mg value of Albian seawater was around –0.4‰.