Dominant Ion Research Articles

Gas flow rate dependence of the discharge characteristics of a helium atmospheric pressure plasma jet interacting with a substrate

A 2D (axisymmetric) computational study of the discharge characteristics of an atmospheric pressure plasma jet as a function of gas flow rate was performed. The helium jet emerged from a dielectric tube, with an average gas flow velocity in the range 2.5–20 m s−1 (1 atm, 300 K) in a nitrogen ambient, and impinged on a substrate a short distance dowstream. The effect of the substrate conductivity (conductror versus insulator) was also studied. Whenever possible, simulation predictions were compared with published experimental observations. Discharge ignition and propagation in the dielectric tube were hardly affected by the He gas flow velocity. Most properties of the plasma jet, however, depended sensitively on the He gas flow velocity, which determined the concentration distributions of helium and nitrogen in the mixing layer forming in the gap between the tube exit and the substrate. At low gas flow velocity, the plasma jet evolved from a hollow (donut-shaped) feature to one where the maximum of electron density was on axis. When the gas flow velocity was high, the plasma jet maintained its hollow structure until it struck the substrate. For a conductive substrate, the radial ion fluxes to the surface were relatively uniform over a radius of ~0.4–0.8 mm, and the dominant ion flux was that of He+. For a dielectric substrate, the radial ion fluxes to the surface peaked on the symmetry axis at low He gas flow velocity, but a hollow ion flux distribution was observed at high gas flow velocity. At the same time, the main ion flux switched from to as the He gas flow velocity increased from a low to a high value. The diameter of the plasma ‘footprint’ on the substrate first increased with increasing He gas flow velocity, and eventually saturated with further increases in velocity.

Model-based performance and energy analyses of reverse osmosis to reuse wastewater in a PVC production site

ABSTRACTA pilot-scale reverse osmosis (RO) followed behind a membrane bioreactor (MBR) was developed for the desalination to reuse wastewater in a PVC production site. The solution–diffusion–film model (SDFM) based on the solution–diffusion model (SDM) and the film theory was proposed to describe rejections of electrolyte mixtures in the MBR effluent which consists of dominant ions (Na+ and Cl−) and several trace ions (Ca2+, Mg2+, K+ and SO42−). The universal global optimisation method was used to estimate the ion permeability coefficients (B) and mass transfer coefficients (K) in SDFM. Then, the membrane performance was evaluated based on the estimated parameters which demonstrated that the theoretical simulations were in line with the experimental results for the dominant ions. Moreover, an energy analysis model with the consideration of limitation imposed by the thermodynamic restriction was proposed to analyse the specific energy consumption of the pilot-scale RO system in various scenarios.

Trends in riverine element fluxes: A chronicle of regional socio-economic changes

We show how concentrations of water solutes in the Vltava River (Czech Republic) and their riverine outputs from the catchment were modified by socio-economic changes, land use, and hydrology between 1960 and 2015. In the early 1960s, HCO3 and Ca were the dominant ions. During 1960–1989 (a period of planned economy with an over-use of synthetic fertilizers, excessive draining of agricultural land and little environmental protection), the riverine concentrations of strong acid anions (SAAs: SO4, NO3, and Cl) increased 2–4-fold and their leaching was accompanied for by a 1.4–1.8-fold increase in concentrations of Ca, Mg, K, and Na. SAAs mostly originated from diffuse agricultural sources (synthetic fertilizers and mineralization of organic matter in freshly drained and deeply tilled agricultural land) and their annual average concentrations (as well as those of Ca, Mg, and K) were positively correlated with discharge. During 1990–2015 (a period of a re-established market economy, reduced fertilization, ceased drainage, partial conversion of arable land to pastures, and increasing environmental protection), concentrations of SO4 and NO3 significantly decreased due to reduced agricultural production and atmospheric pollution, and their positive correlations with discharge disappeared. In contrast, Na and Cl concentrations increased due to more intensive road de-icing, and their concentrations became negatively correlated with discharge. Trends in phosphorus concentrations reflected changes in its input by both diffuse (fertilizers) and point (wastewater) sources and were discharge independent.

Self-consistent simulation studies on effect of methane concentration on microwave assisted H2-CH4 plasma at low pressure

Self-consistent simulations of low-pressure hydrogen-methane plasmas in a microwave-resonating chamber have been conducted. The dynamics of the plasma are dictated by the dominant ion species in the reactor, which is affected by the methane chemistry. Even small concentrations of methane have substantial effects on the plasma, and self-consistent simulations are necessary to capture the wave plasma interaction. In particular, the input power at which the transition between two different coupling regimes, namely a stable single plasma ball regime and a two ball unstable and undesirable plasma regime, takes place depending on the methane composition. The first experimental results show good agreement with the simulations.

Survey of Voyager plasma science ions at Jupiter: 3. Protons and minor ions

AbstractWhen the Voyager 1 and 2 spacecraft flew through the Jovian system in March and July 1979, the Plasma Science instruments measured ions and electrons in the Io plasma torus and plasma sheet between 4.9 and 42 RJ. The dominant ions in the Jovian magnetosphere comprise the first few ionization states of atomic sulfur and oxygen. We present here an analysis of minor ion species H+, Na+, and SO2+. Protons are 1–20% of the plasma between 5 and 30 RJ with variable temperatures ranging by a factor of 10 warmer or colder than the heavy ions. We suggest that these protons, measured deep inside the magnetosphere, are consistent with a source from the ionosphere of ~1.5–7.5 × 1027 protons s−1 (2.5–13 kg/s). Na+ ions are detected between 5 and 40 RJ at an abundance of 1 to 10%, produced by the ionization of the extended neutral cloud emanating from Io that has been observed since 1974. SO2+ ions are detected between 5.31 and 5.07 RJ at an abundance of 0.1–0.6%. These ions clearly come from the plasma interaction with Io's atmosphere, but the exact processes whereby atmospheric molecules escape Io and end up as ions well inside Io's orbit are not clear.

Hydrochemical and isotopic characteristics of groundwater in the northeastern Tennger Desert, northern China

Groundwater is typically the only water source in arid regions, and its circulation processes should be better understood for rational resource exploitation. Stable isotopes and major ions were investigated in the northeastern Tengger Desert, northern China, to gain insights into groundwater recharge and evolution. In the northern mountains, Quaternary unconsolidated sediments, exposed only in valleys between hills, form the main aquifer, which is mainly made of aeolian sand and gravel. Most of the mountain groundwater samples plot along the local meteoric water line (LMWL), with a more depleted signature compared to summer precipitation, suggesting that mountain groundwater was recharged by local precipitation during winter. Most of the groundwater was fresh, with total dissolved solids less than 1 g/L; dominant ions are Na+, SO4 2− and Cl−, and all mineral saturation indices are less than zero. Evaporation, dissolution and cation exchange are the major hydrogeochemical processes. In the southern plains, however, the main aquifers are sandstone. The linear regression line of δD and δ 18O of groundwater parallels the LMWL but the intercept is lower, indicating that groundwater in the plains has been recharged by ancient precipitation rather than modern. Both calcite and dolomite phases in the plains groundwater are close to saturation, while gypsum and halite can still be dissolved into the groundwater. Different recharge mechanisms occur in the northern mountains and the southern plains, and the hydraulic connection between them is weak. Because of the limited recharge, groundwater exploitation should be limited as much as possible.

Magnetic diffusivities in 3D radiative chemo-hydrodynamic simulations of protostellar collapse

Context. Both theory and observations of star-forming clouds require simulations that combine the co-evolving chemistry, magneto-hydrodynamics, and radiative transfer in protostellar collapse simulation. A detailed knowledge of self-consistent chemical evolution for the main charge carriers (both gas species and dust grains) allows us to correctly estimate the rate and nature of magnetic dissipation in the collapsing core. This knowledge is critical to answer one of the most significant issues of star and planet formation: what is the magnitude and spatial distribution of magnetic flux as the initial condition to protoplanetary disk evolution? Aims. We use a chemo-dynamical version of RAMSES, which is described in a companion publication, to follow the chemo-dynamical evolution of collapsing dense cores with various dust properties and interpret differences that occur in magnetic diffusivity terms. These differences are crucial to circumstellar disk formation. Methods. We performed 3D chemo-dynamical simulations of 1 M⊙ isolated dense core collapse for a range in dust size assumptions. The number density of dust and its mean size affect the efficiency of charge capturing and the formation of ices. The radiative hydrodynamics and dynamical evolution of chemical abundances were used to reconstruct the magnetic diffusivity terms for clouds with various magnetisation. Results. The simulations are performed for a mean dust size ranging from 0.017 μm to 1 μm, and we adopt both a fixed dust size and a dust size distribution. The chemical abundances for this range of dust sizes are produced by RAMSES and serve as inputs to calculations of Ohmic, ambipolar, and Hall diffusivity terms. Ohmic resistivity only plays a role at the late stage of the collapse in the innermost region of the cloud where gas density is in excess of a few times 1013 cm-3. Ambipolar diffusion is a dominant magnetic diffusivity term in cases where mean dust size is a typical ISM value or larger. We demonstrate that the assumption of a fixed dominant ion mass can lead to a one order of magnitude mismatch in the ambipolar diffusion magnitude. The negative Hall effect is dominant during the collapse in case of small dust, i.e. for the mean dust size of 0.02 μm and smaller; we connect this effect to the dominance of negatively charged grains. We find that the Hall effect reverses its sign for mean dust size of 0.1 μm and smaller. The phenomenon of the sign reversal strongly depends on the number of negatively charged dust relative to the ions and the quality of coupling of the charged dust to the magnetic fields. We have adopted different strengths of magnetic fields, β = Pgas/Pmag = 2,5,25. We observe that the variation on the field strength only shifts the Hall effect reversal along the radius of the collapsing cloud, but does not prevent it. Conclusions. The dust grain mean size appears to be the parameter with the strongest impact on the magnitude of the magnetic diffusivity, dividing the collapsing clouds in Hall-dominated and ambipolar-dominated clouds and affecting the size of the resulting disks. We propose to link the dust properties and occurrence and size of disk structures in Class 0 young stellar objects. The proper accounting for dust grain growth in the radiative magneto-hydrodynamical collapse models are as important as coupling the dynamics of the collapse with the chemistry.

11-Year change in water chemistry of large freshwater Reservoir Danjiangkou, China

Danjiangkou Reservoir, an important drinking water source, has become a hot spot internationally due to its draining catchment has been increasingly affected by anthropogenic activities. However, its natural water chemistry (major elements) received little attention though it is crucial for water quality and aquatic ecology. Major ions during 2004–2014 were determined using stoichiometry to explore their shifts and the driving factors in the Danjiangkou Reservoir. Results show significant differences in monthly, spatial and annual concentrations of major ions. Waters are controlled by carbonate weathering with the dominant ions of Ca2+ and HCO3− total contributing 74% to the solutes, which are consistent with regional geography. Carbonate dissolution was produced by sulfuric acid and carbonic acid in particular. The relative abundance of Ca2+ gradually decreases, Na++K+ abundance, however, has doubled in the recent 11years. Population and human activities were the major drivers for several major ions, i.e., Cl− and Na+ concentrations were explained by population and GDP, and SO42− by GDP, industrial sewage and energy consumption. Estimation indicated that domestic salts and atmospheric deposition contributed 56% and 22% to Cl−, respectively. We conclude waters in the Reservoir are naturally controlled by rock weathering whilst some key elements largely contributed by anthropogenic activities.

Mutation Spectrum in the CACNA1A Gene in 49 Patients with Episodic Ataxia

Episodic ataxia is an autosomal dominant ion channel disorder characterized by episodes of imbalance and incoordination. The disease is genetically heterogeneous and is classified as episodic ataxia type 2 (EA2) when it is caused by a mutation in the CACNA1A gene, encoding the α1A subunit of the P/Q-type voltage-gated calcium channel Cav2.1. The vast majority of EA2 disease-causing variants are loss-of-function (LoF) point changes leading to decreased channel currents. CACNA1A exonic deletions have also been reported in EA2 using quantitative approaches. We performed a mutational screening of the CACNA1A gene, including the promoter and 3′UTR regions, in 49 unrelated patients diagnosed with episodic ataxia. When pathogenic variants were not found by sequencing, we performed a copy number variant (CNV) analysis to screen for duplications or deletions. Overall, sequencing screening allowed identification of six different point variants (three nonsense and three missense changes) and two coding indels, one of them found in two unrelated patients. Additionally, CNV analysis identified a deletion in a patient spanning exon 35 as a result of a recombination event between flanking intronic Alu sequences. This study allowed identification of potentially pathogenic alterations in our sample, five of them novel, which cover 20% of the patients (10/49). Our data suggest that most of these variants are disease-causing, although functional studies are required.

Tandem mass spectrometry of laser-reduced anthraquinones for painted works and dyed cultural artifacts

The peculiar ionization of anthraquinones, including the artistic dyes alizarin and purpurin, is examined. When alizarin (MW=240) is ionized by either LDI or MALDI it exhibits a dominant ion of m/z 242 [M+2H]+ with a far greater abundance than expected from the 13C isotopic contribution from the [M+H]+ ion at m/z 241. For the first time, MS/MS analysis of these anomalous [M+2H]+ ions is presented, which indicates that they arise from a laser-induced photoreduction of one of the anthraquinone’s carbonyl groups. MS/MS daughter ions produced from neutral losses of either water or ammonia from the [M+2H]+ ions exhibit different relative abundances, depending upon their respective functional groups’ proximity to the reduced carbonyl. LDI-MS/MS was used for the in situ detection of alizarin in a painting cross section and a swatch of dyed silk.

Soluble ions dynamics in Mediterranean coastal pinewood forest soils interested by saline groundwater

The aim of the study was to evaluate the dynamics of soluble ions in the soils of a pinewood forest of the Mediterranean coastal area in the Province of Ravenna, Italy. A one year monitoring was carried out in four Entisols of the San Vitale pinewood forest, a vulnerable natural area due to subsidence and salt water intrusion. Ionic soluble forms were examined in saturated paste extracts (SPEs) and compared to groundwater soluble forms. Due to the local thermo-pluviometric conditions, both the water table depth and groundwater electrical conductivity (ECw) varied widely ranging respectively from 0 to −162cm in depth and from 2 to 28dS·m−1 in salinity content. As expected, this greatly influenced soluble ions concentrations in soil horizons, leading to variations in salt's speciation.In soils with a deep water table (Typic Ustipsamments), superficial horizons showed a prevalence of Ca2+ and HCO3– ion forms during the whole year, while in the deep horizons, Na+ and Cl− were the dominant ions. During summertime in soils with a shallow water table (Sodic Psammaquents), superficial ions enrichment was detected with Na+ and Cl− ions being prevalent. Autumn and winter rainfall provoked the leaching of both Na+ and especially of Cl− ions, leaving HCO3– as the main anion. In the soils with intermediate water table depth and moderate salinity (Aquic Ustipsamments), less relevant variations were observed. During winter the Ca2+ ion was the most present at the soil surface together with HCO3−. During summer Ca2+ and Cl− were the most present ions at the soil surface. At deeper horizons Na+ and Cl− ions always prevailed. The sodium adsorption ratio (SAR) reached the greatest values (>40) during summertime in Sodic Psammaquents superficial horizons and in Typic Ustipsamments deep horizons. On the basis of mixing curves, Na+ and Cl− displayed a conservative behavior and a likely sea origin. Both the Ca2+ and SO42− ions appeared to be partially released from the solid soil fraction, while the Mg2+ ion seemed to be partially absorbed by the solid matrix. On the basis of the hydrochemical characterization of both groundwater and soil SPEs, it was possible to identify different refreshing and salinization processes along the soil profiles. The one year monitoring of both the whole soil profile and groundwater, never performed before, allows a better understanding of the presence of distinct plant species and disease symptoms.

ToF-SIMS quantification of bromine based insecticide in mosquito netting

Insecticides are used to combat diseases such as malaria by incorporation in or topical application on mosquito netting. Determination of the insecticide available on the surface of the treated material has been difficult to achieve. A recent study of the chlorine based insecticide permethrin in mosquito netting has shown that time-of-flight secondary ion mass spectrometry (ToF-SIMS) was able to detect and, with the development of ion implanted standards, to quantify permethrin on the fiber surface and subsurface. The ion implantation method has been used extensively for SIMS quantification. A similar approach to analysis and quantification has now been achieved for the brominated insecticide deltamethrin, which is used at significantly lower concentrations than permethrin. ToF-SIMS analysis of deltamethrin indicated a dominant bromine ion in the negative ion mass spectrum. 79Br was implanted into high density polyethylene (HDPE), which is the netting material, into acetone washed netting fibers, and into silicon to verify implant dose. ToF-SIMS depth profiles of the implanted HDPE showed a detection limit of 5.2 × 1017 atoms/cm3, which corresponds to a detection limit of 0.046% by weight for deltamethrin. The implanted fiber showed an implant profile superimposed on the bromine contributed from the deltamethrin. The insecticide concentration below the fiber surface at two different locations was measured at 0.17 and 0.23 wt. %, which is in excellent agreement with the insecticide specification of 0.18 wt. % ±25%. Analysis of unimplanted netting fibers showed localized high concentrations of insecticide. The results obtained provide quantitative analysis of the insecticide on the surface and bulk of the netting and are significant to evaluate net performance.

Confinement improvement in the high poloidal beta regime on DIII-D and application to steady-state H-mode on EAST

Systematic experimental and modeling investigations on DIII-D show attractive transport properties of fully non-inductive high βp plasmas. Experiments on DIII-D show that the large-radius internal transport barrier (ITB), a key feature providing excellent confinement in the high βp regime, is maintained when the scenario is extended from q95 ∼ 12 to 7 and from rapid to near-zero toroidal rotation. The robustness of confinement versus rotation was predicted by gyrofluid modeling showing dominant neoclassical ion energy transport even without the E × B shear effect. The physics mechanism of turbulence suppression, we found, is the Shafranov shift, which is essential and sets a βp threshold for large-radius ITB formation in the high βp scenario on DIII-D. This is confirmed by two different parameter-scan experiments, one for a βN scan and the other for a q95 scan. They both give the same βp threshold at 1.9 in the experiment. The experimental trend of increasing thermal transport with decreasing βp is consistent with transport modeling. The progress toward the high βp scenario on Experimental Advanced Superconducting Tokamak (EAST) is reported. The very first step of extending the high βp scenario on DIII-D to long pulse on EAST is to establish a long pulse H-mode with ITB on EAST. This paper shows the first 61 s fully non-inductive H-mode with stationary ITB feature and actively cooled ITER-like tungsten divertor in the very recent EAST experiment. The successful use of lower hybrid wave as a key tool to optimize the current profile in the EAST experiment is also introduced. Results show that as the electron density is increased, the fully non-inductive current profile broadens on EAST. The improved understanding and modeling capability are also used to develop advanced scenarios for the China Fusion Engineering Test Reactor. Overall, these results provide encouragement that the high βp regime can be extended to a lower safety factor and very low rotation, providing a potential path to high performance steady state operation in future devices.

Distinctive features of internally driven magnetotail reconnection

AbstractOnset of reconnection in a tail‐like equilibrium with a finite Bz magnetic field component is studied using 3‐D explicit particle‐in‐cell simulations. Due to a region of a tailward Bz gradient the onset develops spontaneously as the magnetic flux release instability with dominant earthward ion flows. The instability drives the change of magnetic field topology internally, without any external forcing. The distinctive features of this regime are: previously unreported Hall magnetic field patterns; energy conversion near the dipolarization front prior to the X line formation; asymmetry of the energy conversion, plasma heating, and anisotropy relative to the X line, with regions of ion and electron heating out of phase both along and across the tail. These features distinguish the internally driven reconnection regime from similar processes in antiparallel magnetic field configurations as well as interchange and externally driven magnetotail reconnection regimes and can be used to identify the different regimes in upcoming Magnetospheric Multiscale (MMS) mission tail season observations.

PM2.5 Characteristics in Qingdao and across Coastal Cities in China

A year-long study was performed to comprehensively investigate the mass concentration, water-soluble ions, organic and elemental carbons, and elemental components of atmospheric fine particles from March 2006 to February 2007 in Qingdao. The results showed that PM2.5 concentration was over twice the National Ambient Air Quality Standards of 35 μg/m3 (GB3095-2012), with the highest value in winter (110 μg/m3) and the lowest in summer (42.8 μg/m3). Non-sea salt-SO42− (nss-SO42−), NO3−, and NH4+ were the dominant water-soluble ions in PM2.5, and showed the highest concentrations in autumn, winter and autumn, respectively, and all had the lowest concentrations in summer. Organic carbon (OC) and elemental carbon (EC) had the lowest levels in summer and the highest values in winter and autumn, respectively. The lower acetic/formic acid (A/F) ratio in summer suggested a predominant secondary formation of water-soluble organic acids. Cl-depletion mainly occurred in summer, along with the largest sea salt proportion in particles in a year when winds came from the southeastern sea. The enrichment factors (EFs) of elements followed an increasing order: Si, Al, Ti, Mg, Ca, Fe, Na, Sr, K, Mn, Ba, V, Cr, Ni, Co, Sc, Cu, As, Cl, Zn, Pb, S, Br, Cd, and Se. The higher EFs from 10.1 to 10,487 for Sr, K, Mn, Ba, V, Cr, Ni, Co, Sc, Cu, Cl, Zn, Pb, S, Br, Cd, and Se suggested the significant influence of anthropogenic sources in the area. Mass closure showed that (NH4)2SO4, organic matter, and NH4NO3 were the main components, and contributed 31.0%, 25.2%, and 14.0% of PM2.5 mass in Qingdao, respectively. Source apportionment results showed that secondary sulfate, nitrate, and coal combustion were the main sources. Based on this study and previous publications, the PM2.5 characteristics—including seasonality in mass and chemical species concentrations and Cl-depletion in summer—were obtained across coastal cities in China.

Chemical and Sr isotopic characteristics of rainwater on the Alxa Desert Plateau, North China: Implication for air quality and ion sources

The major ions and Sr isotopes in rainwater have been studied during 2013–2015 on the Alxa Desert Plateau in order to identify the source of rainwater chemistry and to assess air quality in the desert area of northern China. The pH and EC values of rainwater vary from 6.7 to 8.1 and from 35 to 1237μScm−1, respectively, at the two meteorological stations (AYQ and YBL) in the Alxa Desert Plateau. Ca2+, SO42−, Na+ and Cl− are the dominant ions in rainwater, possessing >85% of total ions. The mean daily wet deposition fluxes of soluble ions are 8709μeq/m2/d at YBL and 5459μeq/m2/d at AYQ, approaching the values at Xi'an, Beijing, Guangzhou, and Chengdu. Statistical analysis shows that SO42− and NO3− in rainwater were mainly from anthropogenic sources while Ca2+ and K+ originated from terrestrial sources. Cl− was mainly from seawater sources, and Na+ was partly from mineral weathering. Major ions are well correlated with each other in rainwater, revealing that substances of various origins were synchronously carried into the atmosphere by wind. By using Sr isotope techniques, three main end-members controlling base cations of rainwater are identified: silicates, carbonates and seawater. Based on the analyses of acid-soluble fractions of desert soils, local soil dust could be the most important source of base cations in rainwater whereas the effect of the anthropogenic sources could be neglected.

Hydrochemical and isotopic investigation of groundwater of Al-Batin alluvial fan aquifer, Southern Iraq

Major ions and important trace elements in addition to δ18O and δ2H were analysed for 43 groundwater samples sampled from the Al-Batin alluvial fan aquifer, South Iraq. The most dominant ions (with respect to molarity) were: Na+ > Cl− > SO4 2− > Ca2+ > Mg2+ > NO3 − > HCO3 −, with total dissolved solids (TDS) averaging 7855 mg/L. High concentrations were found for the trace elements U, Mo, V, B, Sr, and Cr. This study suggests a hydraulic connection exists near the fan apex between the uppermost part of the Al-Batin aquifer and the underlying Dammam aquifer by means of the Abu-Jir fault system. Except for the effects of extensive irrigation, fertilizer use, and poorly maintained sewers, the groundwater chemistry is mainly controlled by geological processes such as dissolution of evaporites and the enrichment of dissolved ions as a result of the high evaporation and low recharge rate. Furthermore, it is shown that the Kuwaiti fuel–oil burning during Gulf War in 1991 contributed to the enrichment of V and Mo in the studied aquifer. The spatial distribution of most ions appears to generally increase from the south-west towards the north-east, in the direction of groundwater flow. The stable isotopes show heavier values in groundwater with a gradually increasing trend in the direction of groundwater flow due to the decreasing depth to groundwater and thus increasing of evaporation from both groundwater or irrigation return water. Additionally, the stable isotope signature suggests that rainfall from sources in the Arabian Gulf and the Arabian Sea is the major source of recharge for the Al-Batin aquifer. Except for two samples of groundwater, all samples were not suitable for potable use according to the WHO standards. Most of the groundwater is suitable for some agricultural purpose and for livestock water supply. Apart from the high salinity, boron represents the most critical element in the groundwater with respect to agricultural purposes.

Estimating soil salt components and salinity using hyperspectral remote sensing data in an arid area of China

HJ-1A hyperspectral data were used to distinguish topsoil salt components and estimate soil salinity, and the relationship between soil salt chemical components and sensitive bands of soil reflectance spectra was analyzed. The correlation between the soil salt content and the soil spectra obtained from the hyperspectral data was analyzed, proving that topsoil salinity has a very significant correlation with soil reflectance spectra. The relationship between soil reflectance spectra and salt chemical ions was investigated. The soil spectral reflectance at wavelength 510.975 nm and a difference vegetation index were selected to estimate soil salinity and the dominant salt chemical ion concentrations at a depth of 0 to 10 cm using a partial least squares regression model. It was found that the bands sensitive to various levels of chemical components of soil salt were shown to differ, controlled by the dominant component of the soil salt. The sensitive bands in the soil salinity estimation will change with differences in salt components. Estimating the dominant salt in the soil using soil reflectance spectra will lead to greater prediction accuracy. This study provided a possible method for the estimation of salinity and chemical component levels in topsoil, using the hyperspectral data to estimate topsoil salt components.

Spatial and Temporal Variation of Rainwater Chemistry in Ile-Ife and Its Environ, Osun State, Nigeria

The study of the chemical composition of rain water was conducted in Ile – Ife and environs, an agrarian, commercial, residential and semi-industrialised center of Osun state Nigeria. This was with a view to assessing the impact of land use activities on rain water composition and the temporal variation of rainwater chemistry. Physico-chemical parameters such as Turbidity, pH, TDS, Conductivity, Oxygen parameters, Alkalinity, Acidity, Hardness and Major ions (Ca2+, Mg2+, K+, Na+, NO3-, SO4-, HCO3-) were determined, predominant ions were identified. Turbidity, pH, Conductivity, TDS, D.O B.O.D, Alkalinity, Acidity Hardness ranged between 2.90 - 42.84 NTU, 5.65 - 7.40, 6.71 – 122.33 µScm-1, 4.10 –73.27 mg/L, 3.60 – 10.60 mg/L, 0.13 – 7.20 mg/L, 0.33 – 22.0 mg/L, 2.00 – 15.00 mg/L, 0.04 – 1.23 CaCO3mg/l respectively. The dominant ions detected in the study were HCO3-, Mg2+, Na+ and Ca2+. Generally, the mean concentration of ions as expressed in milli-equivalent per Litre showed order of dominance as HCO3- > NO3- > SO42- for the anions and Mg2+ > Na+ > Ca2+ > K+ for cations. The study concluded that land use activities had influence on all the chemical composition of rain water in the study area but more on pH, alkalinity, acidity, bicarbonate. Except sulphate and Nitrate, all other parameters recorded high values in dry season.

Experimental study of the gaseous and particulate matter emissions from a gas turbine combustor burning butyl butyrate and ethanol blends

This paper reports the gaseous pollutants and Particulate Matter (PM) emissions of a gas turbine combustor burning butyl butyrate and ethanol blends. The gas turbine has been tested under two operational conditions to represent the cruising (condition 1) and idling (condition 2) conditions of aero engines. Aviation kerosene RP-3 and four different biofuels using butyl butyrate (BB) and ethanol blends were tested and compared to evaluate the impact of fuel composition on CO, NOx, unburnt hydrocarbon (UHC) and PM emissions under selected two operational conditions. The PM number (PN) concentration and size distributions were measured by a scanning mobility particle sizer (SMPS). The compositions of filter borne PM were analysed by ion chromatograph technique. The concentrations of CO, NOx and UHC were detected and analysed by a gas analyser. Results indicated that under idling and cruising conditions the CO emissions from butyl butyrate and ethanol blends were higher than that of RP-3 due to the relatively lower combustion temperature of the biofuels compared with that of RP-3. Results of the NOx emission comparison indicated the biofuels produced less NOx than RP-3 and the increase of ethanol content in the biofuels could reduce the NOx and UHC emissions. The particles smaller than 20nm played a dominant role in PN emissions at condition 1 with the range from 2×106/cm3 to 4×107/cm3. There was a peak value of particle number concentration with the particle size ranging from about 25nm and 40nm. The PN emission index at condition 1 was higher than that at condition 2 for the biofuels, whilst the trend was opposite to that of RP-3. The ions analysis indicated Ca2+ and SO42− were the two dominant ions in the PM emissions of biofuels.