bluuebunny/crossref_metadata_2025 huggingface dataset:
Climate Change Impacts on Surface Water Quality
Authors: Mujere Never , Moyce William
Published: August 2017

Climate change affects water resources through changes in evaporation, groundwater recharge, temperature, runoff and rainfall. Such changes affect the mobilization of nutrients, distribution and mobility of pollutants in freshwater systems. The direct and indirect climate change impacts on water quality comprise biological, physical and chemical changes. Biological changes include pathogenic microbes in water. Physical changes include increased water temperature, reduced river and lake ice cover, more stable vertical stratification and less mixing of water of deep-water lakes, and changes in water discharge, affecting water level and retention time. Chemical changes include increased nutrient concentrations, water color and decreased oxygen content. However, few scientific works have been recently published on the impacts of climate change on water quality modification. This chapter fills a real gap because there has been no comprehensive review on climate change and river water quality to date. It focuses on the expected water quality impacts of climate change.
Climate Change Impact on the Water Resources of the Limpopo Basin
Authors: Alemaw Berhanu F. , Chaoka Thebeyame Ronald
Published: August 2017

This chapter aims to evaluate the impacts of climate change on both hydrologic regimes and water resources of the Limpopo River Basin in southern Africa. Water resources availability in the basin, in terms of, seasonal and annual runoff (R), soil moisture (S) and actual evapotranspiration (Ea) is simulated and evaluated using the hydrological model, HATWAB. These water balances were computed from precipitation (P), potential evapotranspiration (Ep) and other variables that govern the soil-water-vegetation-atmospheric processes at 9.2km latitude/ longitude gird cells covering the basin. The 1961-90 simulated mean annual runoff reveals mixed patterns of high and low runoff across the region. Although relatively small changes in runoff simulations are prevalent among the three climate change scenarios, generally the OSU simulated relatively high runoff compared to the UKTR and HADCM2 GCMs.
Case Study
Authors: Laletsang Kebabonye , Montshiwa Baram
Published: August 2017

A geophysical survey was carried out in 2012 to map the subsurface geology at a quarry and the village to determine if an alleged damage to houses could have been caused by blasting activity in the quarry. The survey included seismic refraction and reflection recorded with the same spread at source and receiver spacing of 2 m, 3 m, and 5 m. The signal source was a 28-lb. sledge hammer stacked 10 times to increase the S/N. Ground penetrating radar (GPR) was also recorded at a trace spacing of 0.3 m to provide detailed images of the subsurface near the damaged buildings using a 50 MHz unshielded antenna. The seismic refraction and reflection profiles show that the village is underlain by 0-4 m of loose sand, 4-10 m of fractured calcrete, and up to 50 m of fractured silcrete, with the groundwater table at 10-15 m. The GPR images show that the damaged houses sit on thick sand, which cushions them against severe ground vibration. The houses were found to have suffered more damage on the superstructure and this is possibly due to ground vibration amplification at low frequencies of 30-40 Hz.
ALTERAÇÕES AMBIENTAIS NO COMPLEXO ESTUARINO-LAGUNAR DE CANANEIA-IGUAPE: A INFLUÊNCIA DO CANAL ARTIFICIAL DO “VALO GRANDE”
Authors: De Souza Tissiana De Almeida , De Oliveira Regina Célia
Published: August 2017

As áreas litorâneas foram os primeiros setores do território brasileiro a serem ocupadas pelo Homem. Porém a preocupação com estas zonas ainda é bastante recente. O litoral sul paulista encontra-se pouco habitado, quando comparado a outros trechos do litoral do estado de São Paulo, e apresenta um dos mais importantes espaços naturais do Brasil: o Complexo Estuarino-Lagunar de Cananeia-Iguape, o “Lagamar”. O Complexo sofreu uma intensa alteração de seu ambiente a partir do século XIX, resultante da abertura do canal artificial do “Valo Grande”, que liga o rio Ribeira de Iguape diretamente ao Mar Pequeno. Este trabalho tem o objetivo realizar um breve histórico sobre a abertura do Valo, evidenciar as alterações ocorridas na região do Lagamar a partir da efetivação desta obra e mostrar alternativas visando a melhoria das condições ambientais da área. Para tanto, foram realizadas pesquisas bibliográficas a respeito da temática e trabalho de campo, visando enfatizar as transformações ambientais ocorridas na região. Tais alterações também são influenciadas pelos tipos de uso da água e das terras nos setores a montante da bacia do Ribeira de Iguape. Uma possível alternativa para um novo equilíbrio do ambiente estuarino é a instalação de comportas na Barragem do Valo Grande, porém não se sabe como o sistema se comportará perante esta nova dinâmica.
COMPARTIMENTOS DO RELEVO E SUAS CONTRIBUIÇÕES NA ANÁLISE DAS DINÂMICAS DAS PAISAGENS DE PARTE DOS MUNICÍPIOS DE MARABÁ PAULISTA-SP E PRESIDENTE EPITÁCIO-SP
Authors: Fushimi Melina , Nunes João Osvaldo Rodrigues , Hasegawa Júlio Kiyoshi
Published: August 2017

O mapa geomorfológico é uma importante ferramenta que contribui nos estudos referentes ao relevo e, por conseguinte, oferece subsídios aos trabalhos que enfatizam a inter-relação dos aspectos naturais e sociais que compõem as paisagens. Nesse sentido, o objetivo principal do presente artigo foi elaborar o Mapa de Compartimentos do Relevo de parte dos municípios de Marabá Paulista-SP e Presidente Epitácio-SP, ambos localizados no Extremo Oeste do Estado de São Paulo, Brasil, na escala 1:50.000, por meio de técnicas de estereoscopia no ambiente digital e utilizá-lo como auxílio na análise das dinâmicas das paisagens da área de estudo. Para a realização do referido documento cartográfico utilizou-se duas imagens ALOS, sensor PRISM, as quais formam um par estereoscópico, no programa computacional Sistema de Processamento de Imagens Pushbroom. Posteriormente, associado aos trabalhos de campo, foi possível reconhecer três principais compartimentos do relevo: topos das colinas, domínio das vertentes côncavas, convexas e retilíneas e planícies aluviais e alveolares. Em relação aos topos das colinas, identificou-se três padrões, colinas tabulares e aplainadas, colinas amplas suavemente onduladas e colinas onduladas, as quais apresentam, além do relevo, diversidades quanto aos aspectos de declividade, solos, substrato rochoso, curvatura da superfície, uso da terra e cobertura vegetal.
Structures, Dielectric Properties and Luminescence Properties of Nb Doped Li2TiO3 Solid Solution Ceramics
Authors: Wang Fei , Yao Chun Feng , Zeng Qun , Zhou He , Zhou Zhi Yong
Published: August 2017

In this article, the low-firing Li2+xNb3xTi1-4xO3(x = 0.01, 0.02, 0.04, 0.06) ceramics with monoclinic structure have been obtained by the traditional solid solution method and their microwave dielectric properties were investigated in detail. The ceramics were finely densified at lower temperatures around 1100 °C and demonstrated favorable dielectric performances including relatively low permittivities (εr) ranging from 19 to 24, high Q×f values up to 60,000 GHz (fres = 7.89GHz) and small temperature coefficients of the resonate frequency (for x = 0.02, τf = 10.4 ppm/ °C; x = 0.06, τf = -11.5 ppm/ °C). Furthermore, the ceramics could be densified at around 900°C with adding low-amount of B2O3. Especially, the 1wt.% B2O3-doped Li2+xNb3xTi1-4xO3 (x = 0.06) ceramics was sintered well-densified at 900°C and presented good microwave dielectric properties with εr ∼ 22.2, Q×f ∼ 44,000 GHz. In addition, these ceramics have luminescence properties, which indicated that the ceramics would be applied in LTCC and/or luminescence applications as new luminescence LTCC (low temperature co-fired ceramics) materials.
Effect of Fibers Length and Fibers Content on the Splitting Tensile Strength of Coconut Fibers Reinforced Concrete Composites
Authors: Lumingkewas Riana H. , Husen Abrar , Andrianus Rendy
Published: August 2017

Tests on the Indonesian coconut fiber showed that, compared to the results of previous studies, tensile strength and tension failure improved after the fiber was washed with water and dried. This study aims to obtain the effects of fiber length and fiber content on splitting tensile strength behavior of the concrete composite reinforced with coconut fiber. Experimental observations were carried out on the splitting tensile strength of coconut fibers as determined by the fiber content (1, 2, 3, and 4 % by a mass ratio of fiber per cement) and the length of the fibers (5, 20, 40 mm) in the concrete. The results show that a coconut fiber length of 5 mm and a fiber content of 3 % in fiber concrete composite gives the composite 1.28 times higher splitting tensile strength than plain concrete. The density of the fiber concrete composite decreases with the addition of coconut fiber content.
Effect of Carbon Dioxide Curing on Strength Development of Cement Mortar
Authors: Lee Ming Gin , Wang Wei Chien , Huang Yi Shuo , Su Yu Min , Jiang Quan Zhou
Published: August 2017

This study was conducted to assess the acceleration of strength development by CO2 curing and to evaluate the strength and microstructure of two cement mortars. Three curing pressures (1, 5, 8 bars), three curing time (20, 120, 180 minutes) and four CO2 concentration (0%, 25%, 50% and 100%) were used in this investigation. Two mortar specimens are made with Type Ι Portland cement and oil-well cement. After the CO2 curing duration and demolding, the mortar samples were assessed through the mass gain, the compressive strength, the pressure drop, the temperature rise in the curing chamber, and the microstructure characteristics. The performance of the CO2 cured mortars was found through the measurement of pressure drop, temperature rise, strength development, mass gain and carbonation. In general, higher CO2 concentration, longer carbonation time, higher CO2 pressure could increase the compressive strength of the mortar and promote more CO2 absorption. The better results obtained from this study are the Type 1 cement mortars curing three hours under 5-bar pressure with 100% CO2 concentration using one-time supply method. The three-hour mortar samples had a high percent strength development. The increasing of CO2 concentration results in higher carbonation degree of mortar, more mass gain, and a stiffer and denser material.
Study on Methane Adsorption Capacity of Sensor Probe Based on Lead-Free Piezoelectric Resonance Modified by Zeolite X
Authors: Du Jie , Du Hui Ling , An Qun Li
Published: August 2017

The preparation and adsorption capacity of a methane based sensor probe based on lead-free piezoelectric resonance ceramics were investigated in this paper. The zeolite X which synthesized via hydro-thermal process was used to modify the sensor probe surface. The phase structure and microstructure of the zeolite membranes was examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM).Due to the special crystal structure, the zeolite X molecular contain a regular form, uniform pore, larger surface area and a strong surface polarity. In order to test the sensor probe sensitivity, the impedance spectrum of methane adsorption sensitivity was measured at a methane concentration range from 0 to 5%. The results indicate that the sensor probe exhibits enhanced sensitivity with an offset resonant frequency of 590Hz especially at the lower methane concentration found in coal mining. The sensitivity can reach 165 Hz/1% CH4 at the concentration of methanol below 3%. With further increase of methane concentration from 3% to 5%, the sensitivity of sensor probe dropped slightly to 120Hz/1% CH4.
New Methodology of Controlling Mechanical Properties of Materials
Authors: Kotowski Romuald , Alshits V.I. , Darinskaya E.V. , Koldaeva M.V. , Petrzhik E.A. , Tronczyk P.
Published: August 2017

The new relations in kinematics of the magnetoplasticity phenomenon in nonmagnetic materials based on the experimental studies and the computer simulations are presented. The movement of the crystal dislocations, the fundamental crystal defects responsible for plastic deformations, through the random distribution of the point defects, being the obstacles for the motion of the dislocation, is discussed. It is shown that the mean value of the obstacles on the dislocation line does not depend on their concentration C in the sample and the critical dispatching force is proportional to √C.
Investigation on Jurassic Shale Gas Reservoir Characteristics from Northern Qaidam Basin
Authors: Xu Gui Xi , Wang Shu Zhong , Luo Xiang Rong , Jing Ze Feng
Published: August 2017

The Jurassic continental shale from northern Qaidam basin was selected as the research object, through the analysis of X-ray diffraction (XRD), field emission scanning electron microscopy (SEM) and nitrogen adsorption experiment, the mineral composition and pore structure characteristics of Jurassic continental shale from the northern Qaidam basin have been investigated in detail. All shale samples studied are quite rich in clay minerals. The clay mineral content ranges from 59.8% to 83.3% with an average of 74.6%, and the brittle mineral content accounts for 16.5% to 39.3%. Nitrogen adsorption test results indicate that for mesopores and macropores of shale samples the average pore width is 2~200 nm, mainly centering on 10~50 nm, and the micropores of the shale samples have a centralized distribution of 0.5~1 nm. The shale samples show high specific surface areas of 4.6~15.2 m2/g. According to SEM results, interparticle mineral matrix pores are main pore type and slit-type pore are well developed.
Experimental Evaluation of the Chill Casting Method for the Fabrication of LM-25 Aluminum Alloy-Borosilicate Glass (p) Composites
Authors: Hiremath Anupama , Hemanth Joel
Published: August 2017

The paper investigates the novelty of application of end chills in fabricating Aluminum alloy metal matrix composites. An effort has also been made to evaluate the effect of chill material on the soundness of the castings obtained. The required composites were prepared using LM-25 Aluminum alloy as matrix material in which different weight percent of Borosilicate glass particles were added ranging from 3 wt.% to 12 wt.%. The variation in weight percent was brought about in steps of 3%. The fabrication of the composites was carried out in sand molds by incorporating two metallic (copper and Steel) and two non-metallic (Graphite and Silicon carbide) end chills. The specimens for strength and hardness tests were prepared as per ASTM standards and the specimens were drawn from near chill-end as well as from farther away from chill end. The microstructure of the specimens reveal a refined grain structure proving the sound quality of the castings. The result analysis also leads to the conclusion that metallic chills are more beneficial as compared to non-metallic chills for obtaining a good quality composites. Copper chill with a high volumetric heat capacity proved to be the best chill material amongst the others.
An Alternative Crosslinking of Epoxidized Natural Rubber with Maleic Anhydride
Authors: Srirachya Nuttida , Kobayashi Takaomi , Boonkerd Kanoktip
Published: August 2017

This study investigated a novel crosslinking agent for epoxidized natural rubber (ENR). The result showed that it was possible to thermally crosslink ENR with maleic anhydride (MA). No additional catalyst was needed. FT-IR spectra revealed that after heating the ENR mixed with MA, there was the formation of the ester linkages. The crosslinking of ENR via these newly formed linkages was confirmed by the formation of gel once the heated rubber sample was immersed in toluene. The rheographs indicated that the crosslinking can take place at 80 °C and the curing rate and degree of crosslinking were dependent of the MA content. The cured ENR with MA showed higher decomposition temperature and better tensile strength than the uncured one.
Development of Interactive Learning Materials in Engineering of Manufacturing Processes
Authors: Hernández-Castellano Pedro M. , Marrero-Alemán M. Dolores , Aranda-Loureiro Ana M. , Ortega-García Fernando , Paz-Hernández Rubén , Benítez-Vega Antonio N.
Published: August 2017

This work presents several interactive learning materials developed by the Group of Educational Innovation Manufacturing Engineering of the University of Las Palmas de Gran Canaria. This work presents the methodology followed, the main results achieved, the first classroom experiences, their evolution, new materials that are being developed, and the conclusions obtained from this line of work.
IL-33 Signaling Regulates Innate IL-17A and IL-22 Production via Suppression of Prostaglandin E2 during Lung Fungal Infection
Authors: Garth Jaleesa M. , Reeder Kristen M. , Godwin Matthew S. , Mackel Joseph J. , Dunaway Chad W. , Blackburn Jonathan P. , Steele Chad
Published: August 2017

Members of the IL-1 family play protective and regulatory roles in immune defense against the opportunistic mold Aspergillus fumigatus. In this study, we investigated the IL-1 family member IL-33 in lung defense against A. fumigatus. IL-33 was detected in the naive lung, which further increased after exposure to A. fumigatus in a dectin-1–independent manner. Mice deficient in the receptor for IL-33 (Il1rl1−/−) unexpectedly demonstrated enhanced lung clearance of A. fumigatus. IL-33 functioned as a negative regulator of multiple inflammatory cytokines, as IL-1α, IL-1β, IL-6, IL-17A, and IL-22 were significantly elevated in fungal-exposed Il1rl1−/− mice. Subsequently, IL-33 administration to normal mice attenuated fungal-induced IL-17A and IL-22, but not IL-1α, IL-1β, or IL-6, production. IL-33–mediated regulation of IL-17A and IL-22 did not involve the modulation of IL-23 but rather PGE2; PGE2 was significantly increased in fungal-exposed Il1rl1−/− mice, and normal mice produced less PGE2 after fungal exposure when administered IL-33, suggesting that IL-33–mediated regulation of IL-17A and IL-22 occurred at the level of PGE2. This was confirmed by in vivo cyclooxygenase 2 inhibition, which attenuated fungal-induced IL-17A and IL-22, as well as IL-1α, IL-1β, and IL-6, production in Il1rl1−/− mice, resulting in impaired fungal clearance. We also show that a PGE2 receptor agonist increased, whereas a PGE2 synthase inhibitor decreased, the levels of IL-17A and IL-22 but not IL-1α, IL-1β, or IL-6. This study establishes novel mechanisms of innate IL-17A/IL-22 production via PGE2 and regulation of the PGE2/IL-17A/IL-22 axis via IL-33 signaling during lung fungal exposure.
Integrin-Linked Kinase Expression in Myeloid Cells Promotes Inflammatory Signaling during Experimental Colitis
Authors: Ahmed Afsar U. , Yim Howard C. H. , Alorro Mariah , Ernst Matthias , Williams Bryan R. G.
Published: August 2017

The pathology of inflammatory bowel diseases is driven by the inflammatory signaling pathways associated with mucosal epithelial damage. Myeloid cells are known to play an essential role in mediating epithelial inflammatory responses during injury. However, the precise role of these cells in stimulating intestinal inflammation and the subsequent tissue damage is unclear. In this article, we show that expression of integrin-linked kinase (ILK) in myeloid cells is critical for the epithelial inflammatory signaling during colitis induced by dextran sodium sulfate. Myeloid ILK (M-ILK) deficiency significantly ameliorates the pathology of experimental colitis. In response to dextran sodium sulfate, colonic infiltration of neutrophils and inflammatory cytokine production are impaired in M-ILK–deficient mice, and activation of epithelial NF-κB and PI3K signaling pathways are restricted by the M-ILK deficiency. In contrast, reduced epithelial damage in M-ILK–deficient mice is correlated with elevated levels of epithelial Stat3 activation and proliferation. Moreover, M-ILK–dependent inflammatory signaling in the mucosal epithelium can be therapeutically targeted by the pharmacological inhibition of ILK during experimental colitis. Collectively, these findings identify M-ILK as a critical regulator of epithelial inflammatory signaling pathways during colitis and, as a consequence, targeting M-ILK could provide therapeutic benefit.
Cutting Edge: IL-2–Induced Expression of the Amino Acid Transporters SLC1A5 and CD98 Is a Prerequisite for NKG2D-Mediated Activation of Human NK Cells
Authors: Jensen Helle , Potempa Marc , Gotthardt Dagmar , Lanier Lewis L.
Published: August 2017

Priming of human NK cells with IL-2 is necessary to render them functionally competent upon NKG2D engagement. We examined the underlying mechanisms that control NKG2D responsiveness in NK cells and found that IL-2 upregulates expression of the amino acid transporters SLC1A5 and CD98. Using specific inhibitors to block SLC1A5 and CD98 function, we found that production of IFN-γ and degranulation by CD56bright and CD56dim NK cells following NKG2D stimulation were dependent on both transporters. IL-2 priming increased the activity of mTORC1, and inhibition of mTORC1 abrogated the ability of the IL-2–primed NK cells to produce IFN-γ in response to NKG2D-mediated stimulation. This study identifies a series of IL-2–induced cellular changes that regulates the NKG2D responsiveness in human NK cells.
GeoConnections geospatial return on investment case study: BCeMap (MASAS)
Authors: Stewart M A
Published: August 2017

In late 2009 GeoConnections commissioned a series of Geospatial Return on Investment Case Studies to add to the body of knowledge of case studies based on the GITA ROI methodology for financial analysis of geospatial projects. This study focuses on BCeMap,
developed by Emergency Management BC (EMBC) and GeoBC to enhance the Emergency Management Information Service (EMIS) being implemented by EMBC. The BC Emergency Map Viewer (BCeMap) as part of the Multi-Agency Situational Awareness System (MASAS) is intended to enable emergency management
practitioners in preparing for and mitigating the impacts of emergency incidents through timely sharing of geospatially referenced information. BceMap focuses on situational awareness data aggregation and connection to the national MASAS.
BCeMap provides a single resource to aggregate relevant incident data for emergency management and public safety personnel within BC and across Canada (via the MASAS integration) rather than use of several disparate systems where overlap, higher level effects and trends could be overlooked. In
addition to the inherent efficiencies of seeing multiple data types in one common view, BCeMap has the potential to improve agency collaboration and improve public safety.
BCeMap was developed as a pilot project for the 2010 Olympic and Paralympic Games, using $198,000 in GeoConnections funding and matching in-kind resources. The pilot demonstrated capabilities for southwest British Columbia in the area where the games were held. EMBC is currently working to secure
funding to move BCeMap to a full production mode and to extend its data capabilities to include the entire province. There is also an effort to extend awareness and training regarding the tool set throughout the stakeholder community.
Areas of where greatest tangible benefits were projected for this study include:
- Improved staff efficiency for routine operations
- Improved efficiency for event response
- Greater efficiency in protection of critical infrastructure
- Greater efficiency in preservation of business continuity
Areas where additional significant benefits were projected include: better retention of volunteers, improved effectiveness of volunteers, enhanced revenue from critical infrastructure owners, improved logistics regarding available transport during events, cost avoidance from redundant field data
collection in areas with frequent fires, time saved maintaining critical infrastructure contact information, and time saved seeking information by district health staff.
Forward-looking five-year analysis of BCeMap: Cumulative benefits are $2.4M. Net Present Value is $1.8M, with an annualized Return on Investment of 60%. Payback period is two years. This high rate of return and short payback period points to the dramatic benefits that can be realized through use
of real-time data feeds, development of standards to support interoperability, and implementation of interagency data sharing for situational awareness.
Details and preliminary positive evaluation of a test seismic interferometry survey at an active VMS mine near Snow Lake, Manitoba
Authors: Craven J A , Cheraghi S , Roberts B J , Bellefleur G , Schetselaar E , Melanson D , Bancroft B , Miah K
Published: August 2017

Seismic reflections methods are a powerful tool to detect and image structures associated with volcanogenic massive sulphide (VMS) deposits. Seismic interferometry has recently been developed as a robust method to process passive seismic data and image geological
features. In order to test the capability of seismic interferometry to image ore deposits in the crystalline rock environment approximately 300 hours of ambient noise data covering an area of 4 km² were acquired over the Lalor mining area, near Snow Lake, MB, Canada,. The interferometry survey
consisted of 336 receivers installed in a grid comprising sixteen lines. The study area encompasses the Lalor deposit, a 27 Mt VMS deposit located at a depth of ~700 m. A distinct, overlapping 3D active source seismic survey was also acquired in the area and we use it here to evaluate our
interferometry results. An estimate of the seismic wave field (Green's function) is retrieved by crosscorrelating the noise between all receiver locations in each hourly segment of passive seismic data. The crosscorrelated results are summed to generate 'virtual' shot gathers at each physical
receiver location. The virtual data is processed along all 2D lines with conventional methods similar to those applied to active 3D data. The DMO-stacked section obtained reveals a number of events, some more coherent than observed on the active seismic section. Of particular interest is an event
possibly associated with one of the lenses associated with the massive sulphide deposit. A comparable event is also observed on the active seismic data. These results are encouraging and demonstrate the benefits of ambient noise measurements and interferometry in for mineral exploration in
crystalline rock environment.
Enumerating Unlabelled Embeddings of Digraphs
Authors: Chen Yichao , Gao Xiaojian , Huang Yuanqiu
Published: August 2017

A 2-cell embedding of an Eulerian digraph D into a closed surface is said to be directed if the boundary of each face is a directed closed walk in D. In this paper, a method is developed with the purpose of enumerating unlabelled embeddings for an Eulerian digraph. As an application, we obtain explicit formulas for the number of unlabelled embeddings of directed bouquets of cycles Bn, directed dipoles OD2n and for a class of regular tournaments T2n+1.
Mixing state of oxalic acid containing particles in the rural area of Pearl River Delta, China: implications for the formation mechanism of oxalic acid
Authors: Cheng Chunlei , Li Mei , Chan Chak K. , Tong Haijie , Chen Changhong , Chen Duohong , Wu Dui , Li Lei , Wu Cheng , Cheng Peng , Gao Wei , Huang Zhengxu , Li Xue , Zhang Zhijuan , Fu Zhong , Bi Yanru , Zhou Zhen
Published: August 2017

Abstract. The formation of oxalic acid and its mixing state in atmospheric particulate matter (PM) were studied using a single-particle aerosol mass spectrometer (SPAMS) in the summer and winter of 2014 in Heshan, a supersite in the rural area of the Pearl River Delta (PRD) region in China. Oxalic-acid-containing particles accounted for 2.5 and 2.7 % in total detected ambient particles in summer and winter, respectively. Oxalic acid was measured in particles classified as elemental carbon (EC), organic carbon (OC), elemental and organic carbon (ECOC), biomass burning (BB), heavy metal (HM), secondary (Sec), sodium-potassium (NaK), and dust. Oxalic acid was found predominantly mixing with sulfate and nitrate during the whole sampling period, likely due to aqueous-phase reactions. In summer, oxalic-acid-containing particle number and ozone concentration followed a very similar trend, which may reflect the significant contribution of photochemical reactions to oxalic acid formation. The HM particles were the most abundant oxalic acid particles in summer and the diurnal variations in peak area of iron and oxalic acid show opposite trends, which suggests a possible loss of oxalic acid through the photolysis of iron oxalato-complexes during the strong photochemical activity period. In wintertime, carbonaceous particles contained a substantial amount of oxalic acid as well as abundant carbon clusters and BB markers. The general existence of nitric acid in oxalic-acid-containing particles indicates an acidic environment during the formation process of oxalic acid. The peak areas of nitrate, sulfate and oxalic had similar temporal change in the carbonaceous type oxalic acid particles, and the organosulfate-containing oxalic acid particles correlated well with total oxalic acid particles during the haze episode, which suggests that the formation of oxalic acid is closely associated with the oxidation of organic precursors in the aqueous phase.
Possible climatic implications of high-altitude black carbon emissions
Authors: Govardhan Gaurav , Satheesh Sreedharan Krishnakumari , Nanjundiah Ravi , Moorthy Krishnaswamy Krishna , Babu Surendran Suresh
Published: August 2017

Abstract. On account of its strong absorption of solar and terrestrial radiation, black carbon (BC) aerosol is known to impact large-scale systems, such as the Asian monsoon and the Himalayan glaciers, in addition to affecting the thermal structure of the lower atmosphere. While most studies focus on the near-surface abundance and impacts of BC, our study examines the implications of sharp and confined layers of high BC concentration (called elevated BC layers) at altitudes more than 4 km over the Indian region using the online regional chemistry transport model (WRF-Chem) simulations. These elevated BC layers were revealed in the recent in situ measurements using high-altitude balloons carried out on 17 March 2010, 8 January 2011 and 25 April 2011. Our study demonstrates that high-flying aircraft (with emissions from the regionally fine-tuned MACCity inventory) are the most likely cause of these elevated BC layers. Furthermore, we show that such aircraft-emitted BC can be transported to upper tropospheric or lower stratospheric heights ( ∼  17 km) aided by the strong monsoonal convection occurring over the region, which is known to overshoot the tropical tropopause, leading to the injection of tropospheric air mass (along with its constituent aerosols) into the stratosphere. We show observational evidence for such an intrusion of tropospheric BC into the stratosphere over the Indian region using extinction coefficient and particle depolarisation ratio data from CALIOP Lidar on-board the CALIPSO satellite. We hypothesise that such intrusions of BC into the lower stratosphere and its consequent longer residence time in the stratosphere have significant implications for stratospheric ozone, especially considering the already reported ozone-depleting potential of BC.
Importance of the Saharan heat low in controlling the North Atlantic free tropospheric humidity budget deduced from IASI δD observations
Authors: Lacour Jean-Lionel , Flamant Cyrille , Risi Camille , Clerbaux Cathy , Coheur Pierre-François
Published: August 2017

Abstract. The isotopic composition of water vapour in the North Atlantic free troposphere is investigated with Infrared Atmospheric Sounding Interferometer (IASI) measurements of the D ∕ H ratio (δD) above the ocean. We show that in the vicinity of West Africa, the seasonality of δD is particularly strong (130 ‰), which is related with the influence of the Saharan heat low (SHL) during summertime. The SHL indeed largely influences the dynamic in that region by producing deep turbulent mixing layers, yielding a specific water vapour isotopic footprint. The influence of the SHL on the isotopic budget is analysed on various time and space scales and is shown to be large, highlighting the importance of the SHL dynamics on the moistening and the HDO enrichment of the free troposphere over the North Atlantic. The potential influence of the SHL is also investigated on the inter-annual scale as we also report important variations in δD above the Canary archipelago region. We interpret the variability in the enrichment, using backward trajectory analyses, in terms of the ratio of air masses coming from the North Atlantic and air masses coming from the African continent. Finally, the interest of IASI high sampling capabilities is further illustrated by presenting spatial distributions of δD and humidity above the North Atlantic from which we show that the different sources and dehydration pathways controlling the humidity can be disentangled thanks to the added value of δD observations. More generally, our results demonstrate the utility of δD observations obtained from the IASI sounder to gain insight into the hydrological cycle processes in the West African region.
Observational evidence for the formation of DMS-derived aerosols during Arctic phytoplankton blooms
Authors: Park Ki-Tae , Jang Sehyun , Lee Kitack , Yoon Young Jun , Kim Min-Seob , Park Kihong , Cho Hee-Joo , Kang Jung-Ho , Udisti Roberto , Lee Bang-Yong , Shin Kyung-Hoon
Published: August 2017

Abstract. The connection between marine biogenic dimethyl sulfide (DMS) and the formation of aerosol particles in the Arctic atmosphere was evaluated by analyzing atmospheric DMS mixing ratio, aerosol particle size distribution and aerosol chemical composition data that were concurrently collected at Ny-Ålesund, Svalbard (78.5° N, 11.8° E), during April and May 2015. Measurements of aerosol sulfur (S) compounds showed distinct patterns during periods of Arctic haze (April) and phytoplankton blooms (May). Specifically, during the phytoplankton bloom period the contribution of DMS-derived SO42− to the total aerosol SO42− increased by 7-fold compared with that during the proceeding Arctic haze period, and accounted for up to 70 % of fine SO42− particles (<  2.5 µm in diameter). The results also showed that the formation of submicron SO42− aerosols was significantly associated with an increase in the atmospheric DMS mixing ratio. More importantly, two independent estimates of the formation of DMS-derived SO42− aerosols, calculated using the stable S-isotope ratio and the non-sea-salt SO42− ∕ methanesulfonic acid ratio, respectively, were in close agreement, providing compelling evidence that the contribution of biogenic DMS to the formation of aerosol particles was substantial during the Arctic phytoplankton bloom period.
Ozone Response to Emission Reductions in the Southeastern United States
Authors: Blanchard Charles L. , Hidy George M.
Published: August 2017

Abstract. Ozone (O3) formation in the southeastern U.S. is studied in relation to nitrogen oxide (NOx) emissions using long-term (1990s–2015) surface measurements of the Southeastern Aerosol Research and Characterization (SEARCH) network, U.S. Environmental Protection Agency (EPA) O3 measurements, and EPA Clean Air Status and Trends Network (CASTNet) nitrate deposition data. CASTNet data show declining wet and dry nitrate deposition since the late 1990s, with total (wet plus dry) nitrate deposition fluxes decreasing linearly in proportion to reductions of NOx emissions in in Alabama and Georgia. Annual nitrate deposition rates at Georgia and Alabama CastNet sites correspond to 30 % of Georgia emission rates and 36 % of Alabama emission rates, respectively. The fraction of NOx emissions lost to deposition has not changed over time. SEARCH and EPA CASTNet sites exhibit comparable downward trends in mean annual nitric acid (HNO3) concentrations. Mean annual total oxidized nitrogen (NOy) mixing ratios at SEARCH sites declined in proportion to NOx emission reductions. Annual 4th-highest daily peak 8-hour O3 mixing ratios at EPA monitoring sites in Georgia, Alabama, and Mississippi exhibit statistically-significant (p
Insights into organic-aerosol sources via a novel laser-desorption/ionization mass spectrometry technique applied to one year of PM10 samples from nine sites in central Europe
Authors: Daellenbach Kaspar R. , El-Haddad Imad , Karvonen Lassi , Vlachou Athanasia , Corbin Joel C. , Slowik Jay G. , Heringa Maarten F. , Bruns Emily A. , Luedin Samuel M. , Jaffrezo Jean-Luc , Szidat Sönke , Piazzalunga Andrea , Gonzalez Raquel , Fermo Paola , Pflueger Valentin , Vogel Guido , Baltensperger Urs , Prévôt André S. H.
Published: August 2017

Abstract. We assess the benefits of offline laser-desorption/ionization mass spectrometry (LDI-MS) in understanding ambient particulate matter (PM) sources. The technique was optimized for measuring PM collected on quartz-fiber filters using silver nitrate as an internal standard for m/z calibration. This is the first application of this technique to samples collected at nine sites in central Europe throughout the entire year 2013 (819 samples). Different PM sources were identified by positive matrix factorization (PMF) including also concomitant measurements (such as NOx, levoglucosan, and temperature). By comparison to reference mass spectral signatures from laboratory wood burning experiments as well as samples from a traffic tunnel, three biomass-burning factors and two traffic factors were identified. The wood-burning factors could be linked to the burning conditions; the factors related to inefficient burns had a larger impact on air quality in southern Alpine valleys than in northern Switzerland. The traffic factors were identified as primary tailpipe exhaust and most possibly aged/secondary traffic emissions, respectively. The latter attribution was supported by radiocarbon analyses of both the organic and elemental carbon. Besides these sources, also factors related to secondary organic aerosol were separated. The contribution of the wood burning emissions based on LDI-PMF correlates well with that based on AMS-PMF analyses, while the comparison between the two techniques for other components is more complex.
Impact of land use and soil properties on soil methane flux response to biochar addition
Authors: Cong Weiwei , Meng Jun , Ying Samantha C.
Published: August 2017

Abstract. Addition of biochar to soils has been shown to increase crop yield and aid in mitigating greenhouse gas emissions by decreasing the extent of soil methane (CH4) flux. Previous studies utilizing metaanalysis to better understand the impact of environmental and management factors on CH4 flux from biochar treated soil systems have provided contrasting results, ranging from significant increase, decrease, to no change in methane flux after amendment. We hypothesized that these discrepancies could be explained by separating studies into two major land use categories, upland and paddy, prior to analysis so that the overall redox conditions are more comparable across studies upon which statistical comparisons are made. Furthermore, past studies did not consider potentially critical soil properties including soil organic carbon, total nitrogen, C/N, and soil texture; a number of biochar properties including biochar pH and C/N; and five additional management and experimental factors. In this study, Hedge's d metric was calculated and Wilcoxon analyses were used in a meta-analysis to determine the impact of these additional factors on methane flux from biochar-amended upland versus paddy soils. We demonstrate that variations in soil characteristics including SOC, C/N, and pH significantly influences the methane flux from biochar treated soils, while biochar characteristics and management practices have less to no effect as determined by the magnitude of the Hedge's d metric. Soils with low SOC, total nitrogen, C/N, acidic or alkaline pH exhibited lowest CH4 emission rates/highest CH4 uptake rates, whereas soils with higher SOC content, C/N, and circumneutral pH exhibited higher CH4 emission with biochar addition. Several possible mechanisms are suggested to explain the role of these variables in CH4 cycling. Results from this study will be used to evaluate the input parameters for building a linear additive model to quantitatively predict soil methane flux in response to biochar additions. Ultimately, implementation of the linear additive model can be extremely valuable for advising agricultural practices toward minimize methane emissions or maximizing methane sink strength. We suggest that additional field and controlled experiments be performed to better define the reaction network that controls methane flux from biochar treated soils, with particular attention to paddy soils where studies are still lacking.
Soil solution phosphorus turnover: derivation, interpretation, and insights from a global compilation of isotope exchange kinetic studies
Authors: Helfenstein Julian , Jegminat Jannes , McLaren Timothy I. , Frossard Emmanuel
Published: August 2017

Abstract. The exchange rate of inorganic phosphorus (P) between the soil solution and solid phase, also known as soil solution P turnover, is essential for describing the kinetics of bioavailable P. While soil solution P turnover (Km) can be determined by tracing radioisotopes in a soil-solution system, few studies have done so. We believe that this is due to a lack of understanding on how to derive Km from isotopic exchange kinetic (IEK) experiments, a widespread form of radioisotope dilution study. Here, we provide a derivation of calculating Km using parameters obtained from IEK experiments. We then calculated Km for 217 soils from published IEK experiments in terrestrial ecosystems, and also for that of 18 long-term P fertilizer field experiments. Analysis of the global compilation dataset revealed a negative relationship between concentrations of soil solution P and Km. Furthermore, Km buffered isotopically exchangeable P in soils with low concentrations of soil solution P. This finding was supported by an analysis of long-term P fertilizer field experiments, which revealed a negative relationship between Km and phosphate buffering capacity. Our study thus highlights the potential of Km for future studies – not only for P, but also for other environmentally-relevant, strongly-sorbing elements with radioisotopes such as zinc, cadmium, nickel, arsenic, or uranium.
10Be systematics in the Tsangpo-Brahmaputra catchment: the cosmogenic nuclide legacy of the eastern Himalayan syntaxis
Authors: Lupker Maarten , Lavé Jérôme , France-Lanord Christian , Christl Marcus , Bourlès Didier , Carcaillet Julien , Maden Colin , Wieler Rainer , Rahman Mustafizur , Bezbaruah Devojit , Xiaohan Liu
Published: August 2017

Abstract. The Tsangpo-Brahmaputra River drains the eastern part of the Himalayan range and flows from the Tibetan Plateau through the eastern Himalayan syntaxis downstream to the Indo-Gangetic floodplain and the Bay of Bengal. As such, it is a unique natural laboratory to study how denudation and sediment production processes are transferred to river detrital signals. In this study, we present a new 10Be data set to constrain denudation rates across the catchment and to quantify the impact of rapid erosion within the syntaxis region on cosmogenic nuclide budgets and signals. The measured 10Be denudation rates span around 2 orders of magnitude across individual catchments (ranging from 0.03 to > 4 mm yr−1) and sharply increase as the Tsangpo-Brahmaputra flows across the eastern Himalaya. The increase in denudation rates, however, occurs  ∼  150 km downstream of the Namche Barwa–Gyala Peri massif (NBGPm), an area which has been previously characterized by extremely high erosion and exhumation rates. We suggest that this downstream lag is mainly due to the physical abrasion of coarse-grained, low 10Be concentration, landslide material produced within the syntaxis that dilutes the upstream high-concentration 10Be flux from the Tibetan Plateau only after abrasion has transferred sediment to the studied sand fraction. A simple abrasion model produces typical lag distances of 50 to 150 km compatible with our observations. Abrasion effects reduce the spatial resolution over which denudation can be constrained in the eastern Himalayan syntaxis. In addition, we also highlight that denudation rate estimates are dependent on the sediment connectivity, storage, and quartz content of the upstream Tibetan Plateau part of the catchment, which tends to lead to an overestimation of downstream denudation rates. While no direct 10Be denudation measurements were made in the syntaxis, the dilution of the upstream 10Be signal, measured in Tsangpo-Brahmaputra sediments, provides constraints on the denudation rates in that region. These denudation estimates range from ca. 2 to 5 mm yr−1 for the entire syntaxis and ca. 4 to 28 mm yr−1 for the NBGPm, which is significantly higher than other large catchments. Overall, 10Be concentrations measured at the outlet of the Tsangpo-Brahmaputra in Bangladesh suggest a sediment flux between 780 and 1430 Mt yr−1 equivalent to a denudation rate between 0.7 and 1.2 mm yr−1 for the entire catchment.
Enviro-HIRLAM online integrated meteorology–chemistry modelling system: strategy, methodology, developments and applications (v7.2)
Authors: Baklanov Alexander , Smith Korsholm Ulrik , Nuterman Roman , Mahura Alexander , Nielsen Kristian Pagh , Sass Bent Hansen , Rasmussen Alix , Zakey Ashraf , Kaas Eigil , Kurganskiy Alexander , Sørensen Brian , González-Aparicio Iratxe
Published: August 2017

Abstract. The Environment – High Resolution Limited Area Model (Enviro-HIRLAM) is developed as a fully online integrated numerical weather prediction (NWP) and atmospheric chemical transport (ACT) model for research and forecasting of joint meteorological, chemical and biological weather. The integrated modelling system is developed by the Danish Meteorological Institute (DMI) in collaboration with several European universities. It is the baseline system in the HIRLAM Chemical Branch and used in several countries and different applications. The development was initiated at DMI more than 15 years ago. The model is based on the HIRLAM NWP model with online integrated pollutant transport and dispersion, chemistry, aerosol dynamics, deposition and atmospheric composition feedbacks. To make the model suitable for chemical weather forecasting in urban areas, the meteorological part was improved by implementation of urban parameterisations. The dynamical core was improved by implementing a locally mass-conserving semi-Lagrangian numerical advection scheme, which improves forecast accuracy and model performance. The current version (7.2), in comparison with previous versions, has a more advanced and cost-efficient chemistry, aerosol multi-compound approach, aerosol feedbacks (direct and semi-direct) on radiation and (first and second indirect effects) on cloud microphysics. Since 2004, the Enviro-HIRLAM has been used for different studies, including operational pollen forecasting for Denmark since 2009 and operational forecasting atmospheric composition with downscaling for China since 2017. Following the main research and development strategy, further model developments will be extended towards the new NWP platform – HARMONIE. Different aspects of online coupling methodology, research strategy and possible applications of the modelling system, and fit-for-purpose model configurations for the meteorological and air quality communities are discussed.