Sn Values Research Articles

Extreme values for Sn(σ,t) near the critical line

Let S(σ,t)=1πarg⁡ζ(σ+it) be the argument of the Riemann zeta function at the point σ+it of the critical strip. For n≥1 and t>0 we defineSn(σ,t)=∫0tSn−1(σ,τ)dτ+δn,σ, where δn,σ is a specific constant depending on σ and n. Let 0≤β<1 be a fixed real number. Assuming the Riemann hypothesis, we show lower bounds for the maximum of the function Sn(σ,t) on the interval Tβ≤t≤T and near to the critical line, when n≡1mod4. Similar estimates are obtained for |Sn(σ,t)| when n≢1mod4. This extends the results of Bondarenko and Seip [7] for a region near the critical line. In particular we obtain some omega results for these functions on the critical line.

Geochemical distribution and threshold values determination of heavy metals in stream water in the sub-basins of Vermelho and Sororó rivers, Itacaiúnas River watershed, Eastern Amazon, Brazil

Geochemical survey in the Vermelho (VSB) and Sororo (SSB) sub-basins of the Itacaiunas basin in southeastern Amazonian region has shown that the physical-chemical parameters of stream water do not display accentuated variations between the rainy and dry seasons. Except for Fe and Mn, in general most metals show low contents in water and evidences of significant contamination were not observed. Higher contents were mostly registered during the rainy season. Fe is regularly distributed in water in the studied area and the increase of its concentration was favored by deforestation. Mn contents increase during the dry season possibly due to biogeochemical processes. High Fe and Mn contents in water are inherent to the specific local conditions prevalent in the Amazonian region. Geogenic influence in metal distribution in water is significant for Co, Cr, Cu, Ni, Pb, Sn, V, and Zn. Anthropic effects are subordinate except for Fe and Mn or in local areas. The definition of threshold values for As, Co, Cr, and Pb, was limited, however, threshold values for Cu, Ni, Sn, V, and Zn were estimated for at least one season in each sub-basin. Threshold values of total iron were obtained (5 to 6 mg/L and 2 to 3 mg/L in the rainy and dry seasons, respectively). Estimated Mn threshold values are 0.30 to 0.45 mg/L in the rainy season and in the dry season they decrease to 0.20 to 0.30 mg/L in VSB and increase to 1.3 to 1.4 mg/L in SSB.

PhageWeb - Web Interface for Rapid Identification and Characterization of Prophages in Bacterial Genomes.

This study developed a computational tool with a graphical interface and a web-service that allows the identification of phage regions through homology search and gene clustering. It uses G+C content variation evaluation and tRNA prediction sites as evidence to reinforce the presence of prophages in indeterminate regions. Also, it performs the functional characterization of the prophages regions through data integration of biological databases. The performance of PhageWeb was compared to other available tools (PHASTER, Prophinder, and PhiSpy) using Sensitivity (Sn) and Positive Predictive Value (PPV) tests. As a reference for the tests, more than 80 manually annotated genomes were used. In the PhageWeb analysis, the Sn index was 86.1% and the PPV was approximately 87%, while the second best tool presented Sn and PPV values of 83.3 and 86.5%, respectively. These numbers allowed us to observe a greater precision in the regions identified by PhageWeb while compared to other prediction tools submitted to the same tests. Additionally, PhageWeb was much faster than the other computational alternatives, decreasing the processing time to approximately one-ninth of the time required by the second best software. PhageWeb is freely available at http://computationalbiology.ufpa.br/phageweb.

Time dependent neutron emission rate analysis for neutral-beam-heated deuterium plasmas in a helical system and tokamaks

A neutron emission rate analysis code called FBURN, based on the classical energetic ion confinement assumption with radial diffusion, is developed for the time-dependent analysis of the total neutron emission rate (Sn) in neutral beam (NB) heated deuterium plasmas. The time trend of Sn evaluated by FBURN shows good agreement with the Sn measured by the neutron flux monitor on the deuterium operation of the Large Helical Device. The dependence of Sn on line-averaged electron density (ne_avg) has a peak at ne_avg of around 2.5 × 1019 m−3 in both experiment and calculation. Here, the absolute value of Sn evaluated by calculation agrees with that obtained in experiments within a factor of two. A time trend analysis of Sn in an electron cyclotron heated plasma with a short pulse NB injection is performed. The analysis shows that the diffusion coefficient of co-going transit beam ions is 0.2 to 0.3 m2 s−1. In addition, the diffusion coefficient of helically trapped beam ions decreases from 5 to 3 m2 s−1 with the inward shift of the magnetic axis position. Time-resolved analysis of the triton burnup experiment shows that the diffusion coefficient of tritons is around 0.15 m2 s−1. It is found that the diffusion coefficients of the beam and tritons are of a similar value as obtained in JT-60U. The trend of the triton burnup ratio on the ne_avg calculated by the FBURN agrees with the experiments. The results suggest that the decrease of the triton burnup ratio with the increase of ne_avg is due to the shorter slowing down time of tritons by the decrease of the electron temperature, and the increase of the triton burnup ratio with the increase of ne_avg is due to the diffusion of tritons. Time trend analysis of Sn in the Korea Superconducting Tokamak Advanced Research and the Experimental Advanced Superconducting Tokamak plasmas with a short pulse NB injection is performed. The time trend of Sn is successfully reproduced by FBURN.

Benchmarking PGAA, in-beam NAA, reactor-NAA and handheld XRF spectrometry for the element analysis of archeological bronzes

Novel detection strategies were developed to improve the PGAA methodology in the analysis of bronze and brass objects. Instrumental neutron activation analysis and X-ray fluorescence were also involved in this study for comparison. The approach was tested on a set of IRMM-certified copper alloys. Reference values for the concentrations of four major additive components (As, Zn, Sn, and Pb) were compared with the results obtained by the involved methods. The bias observed between the reference Sn values and the initial PGAA results was successfully addressed by considering the interference of this line with low intensity copper prompt gamma peaks. In this report results are presented, and the analytical merits are compared.

Fault activity, tectonic segmentation, and deformation pattern of the western Himalaya on Ma timescales inferred from landscape morphology

The location and magnitude of Himalayan tectonic activity has been debated for decades, and several aspects remain unknown. For instance, the spatial distribution of crustal shortening that ultimately sustains Himalayan topography and the activity of major fault zones remain unknown at Ma timescales. In this study, we address the spatial deformation pattern in the data-scarce western Himalaya. We calculated catchment averaged, normalized river-steepness indices of non-glaciated drainage basins with tributary catchment areas between 5 and 200 km(2) (n = 2138). We analyzed the spatial distribution of the relative change of river steepness both along and across strike to gain information about the regional distribution of differential uplift pattern and relate this to the activity of distinctive fault segments. For our study area, we observe a positive correlation of averaged k(sn) values with long-term exhumation rates derived from previously published thermochronologic datasets combined with thermal modeling as well as with millennial timescale denudation rates based on cosmogenic nuclide dating. Our results indicate three tectono-geomorphic segments with distinctive landscape morphology, structural architecture, and fault geometry along the western Himalaya: Garhwal-Sutlej, Chamba, and Kashmir Himalaya (from east to west). Moreover, our data recognize distinctive fault segments showing varying thrust activity along strike of the Main Frontal Thrust, the Main Boundary Thrust, and in the vicinity of the steep topographic transition between the Lesser and Greater Himalaya. In this region, we relate out-of-sequence deformation along major basement thrust ramps, such as the Munsiari Thrust with deformation along a mid-crustal ramp along the basal decollement. We suggest that during the Quaternary, all major fault zones in the Western Himalaya experienced out-of-sequence faulting and have accommodated some portion of crustal shortening.

High Performance Tin-coated Vertically Aligned Carbon Nanofiber Array Anode for Lithium-ion Batteries

ABSTRACTThis study reports a high-performance tin (Sn)-coated vertically aligned carbon nanofiber array anode for lithium-ion batteries. The array electrodes have been prepared by coaxial sputter-coating of tin (Sn) shells on vertically aligned carbon nanofiber (VACNF) cores. The robust brush-like highly conductive VACNFs effectively connect high-capacity Sn shells for lithium-ion storage. A high specific capacity of 815 mAh g-1 of Sn was obtained at C/20 rate, reaching toward the maximum value of Sn. However, the electrode shows poor cycling performance with conventional LiPF6 based organic electrolyte. The addition of fluoroethylene carbonate (FEC) improve the performance significantly and the Sn-coated VACNFs anode shows stable cycling performance. The Sn-coated VACNF array anodes exhibit outstanding capacity retention in the half-cell tests with electrolyte containing 10 wt.% FEC and could deliver a reversible capacity of 480 mAh g-1 after 50 cycles at C/3 rate.

Recovery of Cu and Zn from waste printed circuit boards using super-gravity separation

With technological innovation and intense marketing, more and more electric and electronic equipment wastes (e-wastes) are being generated. Printed circuit boards (PCBs) are fundamental components of electronic wastes, which consist of both valuable metals and hazardous materials. An efficient method to recycle metals is an important measure to eliminate or avoid heavy metal hazard and realize resource recovery. In this research, super-gravity separation achieved by high temperature centrifugation was used to recover copper and zinc from waste PCBs. At an optimized temperature of 1300 °C and a gravity coefficient of 1000, the total recovery values of Cu, Zn, Pb, and Sn were 93.23%, 80.86%, 94.54%, and 97.67%, respectively, in the whole separation process. By combining appropriate hydrometallurgy and super-gravity separation of metals or alloys, this clean and efficient process provides a novel way to recycle valuable metals and effectively prevent environmental pollution from PCBs. A large-scale experimental apparatus was designed for handling large volume of WPCBs.

On indices of Wiener and anti-Wiener type

In this paper we define Wiener and anti-Wiener type of indices, so that we first introduce ordering of tree graphs, and then define that a topological index is of Wiener type if it is an increasing function with respect to the introduced order. Similarly, we define that a topological index is of anti-Wiener type if it is a decreasing function with respect to the introduced order. The introduced order of tree graphs has the star Sn for minimal graph, while the path Pn is the maximal graph. Therefore, all indices of Wiener type obtain minimum value for Sn and maximum value for Pn, while the reverse holds for indices of anti-Wiener type. Then we introduce a simple criterion on edge contribution function of a topological index which enables us to establish if a topological index is of Wiener or anti-Wiener type. Finally, we apply our result to several generalizations of Wiener index, such as modified Wiener indices, variable Wiener indices and Steiner k-Wiener index.

Low-temperature melting and centrifugation of lead and tin from metal-rich particles of crushed waste printed circuit boards

The rapid growth of electronic devices, their subsequent obsolescence and disposal has resulted in electronic waste being one of the fastest increasing waste streams worldwide. Printed circuit boards (PCBs) contained substantial quantities of metals in concentrations significantly higher than those typically found in corresponding ores. The high value of valuable metals in the e-waste makes the recycle process attractive economically. The study was focused on an effective process to selectively recycle lead and tin from metal-rich particles of crushed PCBs by melting and centrifugation in low temperature. Centrifugal separation is an efficient technology to strengthen the transmission of multiphase flow and reaction process. The temperature had a great influence on the composition of Pb-Sn alloy, while the gravity coefficient only affected the Pb and Sn recovery values, and had little effect on the mass ratio of Pb and Sn in the obtained alloy. At an optimized temperature of 420 °C and a gravity coefficient of 1000, the recovery values of Pb and Sn were 57.16% and 59.49%, respectively. The total mass fraction and mass ratio of Pb and Sn were 93.58 wt.% and 0.87, respectively. This process provides an effective method to recycle valuable metals from PCBs.

Susceptibility MRI captures nigral pathology in patients with parkinsonian syndromes.

Parkinsonisms are neurodegenerative disorders characterized pathologically by α-synuclein-positive (e.g., PD, diffuse Lewy body disease, and MSA) and/or tau-positive (e.g., PSP, cortical basal degeneration) pathology. Using R2* and quantitative susceptibility mapping, susceptibility changes have been reported in the midbrain of living parkinsonian patients, although the exact underlying pathology of these alterations is unknown. The current study investigated the pathological correlates of these susceptibility MRI measures. In vivo MRIs (T1- and T2-weighted, and T2*) and pathology were obtained from 14 subjects enrolled in an NINDS PD Biomarker Program (PDBP). We assessed R2* and quantitative susceptibility mapping values in the SN, semiquantitative α-synuclein, tau, and iron values, as well as neuronal and glial counts. Data were analyzed using age-adjusted Spearman correlations. R2* was associated significantly with nigral α-synuclein (r = 0.746; P = 0.003). Quantitative susceptibility mapping correlated significantly with Perls' (r = 0.758; P = 0.003), but not with other pathological measurements. Neither measurement correlated with tau or glial cell counts (r ≤ 0.11; P ≥ 0.129). Susceptibility MRI measurements capture nigral pathologies associated with parkinsonian syndromes. Whereas quantitative susceptibility mapping is more sensitive to iron, R2* may reflect pathological aspects of the disorders beyond iron such as α-synuclein. They may be invaluable tools in diagnosing differential parkinsonian syndromes, and tracking in living patients the dynamic changes associated with the pathological progression of these disorders. © 2018 International Parkinson and Movement Disorder Society.

Detecting complexes from edge-weighted PPI networks via genes expression analysis

BackgroundIdentifying complexes from PPI networks has become a key problem to elucidate protein functions and identify signal and biological processes in a cell. Proteins binding as complexes are important roles of life activity. Accurate determination of complexes in PPI networks is crucial for understanding principles of cellular organization.ResultsWe propose a novel method to identify complexes on PPI networks, based on different co-expression information. First, we use Markov Cluster Algorithm with an edge-weighting scheme to calculate complexes on PPI networks. Then, we propose some significant features, such as graph information and gene expression analysis, to filter and modify complexes predicted by Markov Cluster Algorithm. To evaluate our method, we test on two experimental yeast PPI networks.ConclusionsOn DIP network, our method has Precision and F-Measure values of 0.6004 and 0.5528. On MIPS network, our method has F-Measure and Sn values of 0.3774 and 0.3453. Comparing to existing methods, our method improves Precision value by at least 0.1752, F-Measure value by at least 0.0448, Sn value by at least 0.0771. Experiments show that our method achieves better results than some state-of-the-art methods for identifying complexes on PPI networks, with the prediction quality improved in terms of evaluation criteria.

Structural, electric transport response and electro -strain - Polarization effect in La and Ni modified bismuth ferrite nanostructures

In this work, we reported the structural properties, electrical transport response and electro-strain polarization effect of La-Ni bismuth ferrite nanostructures, Bi1-XLaXFe1-YNiYO3 (x = 0.0, 0.1; y = 0.0, 0.03, 0.05, 0.07) prepared via sol gel technique. X-ray diffraction (XRD) analysis confirmed the rhombohedral crystal structure with space group R3c of BiFeO3. The Ni ion doping at a Fe - site in BiFeO3 escorts to some structural changes and the average crystallite size was found to be in range ∼13–20 nm. The higher tensile strain was observed in W-H Plot for the prepared samples. The morphological and chemical composition studies of as prepared samples were carried out via using SEM and EDS. Dielectric constant (έ) and AC conductivity (σAC) were deliberated as a function of frequency in the range 10 Hz to 5 MHz. A significant reduction in the dielectric constant has been observed with increasing Ni doping. An enhancement in the remanent polarization (2Pr) value (up to 1.04 μC/cm2 with applied field 8 kV/cm) and AC conductivity has been observed with La/Ni co-doping. The high Curie temperature (Tc) of BFO makes it a suitable candidate for high temperature electromechanical applications. Moreover, an enhanced value of the electric field driven strain as a function of frequency and the applied field is observed which exhibits highly asymmetric S-E hysteresis loops. The peak to peak strain value of Sp and SN is achieved up to 1.019% and 1.582%, respectively, which is the largest value of strain ever obtained in BiFeO3 based nano ferrites. The highest value of peak to peak strains (SP & SN) and strain memory (Sme) has been observed for Bi0.9La0.1Fe0.93Ni.07O3 sample at 8 kV/cm which makes it a suitable candidate for high temperature electromechanical applications (like sensors and actuators etc) in addition to electronic and magnetic applications.

First-principles studies on electronic structures and optical properties of two-dimensional Sn1−xTi(Zr)xS2 alloys

Through first-principles calculations we study the electronic structures and optical properties of two-dimensional (2D) Sn[Formula: see text]Ti(Zr)[Formula: see text]S2 alloys. The results indicate that the band gap value of Sn[Formula: see text]Ti(Zr)[Formula: see text]S2 alloys is decreased continuously when Ti(Zr) concentration is increased, which is very beneficial to optoelectronic devices applications. Moreover, the static dielectric constant is increased when the Ti(Zr) concentration is increased in the 2D Sn[Formula: see text]Ti(Zr)[Formula: see text]S2 alloys. In addition, we also calculate the imaginary part [Formula: see text] dispersion of Sn[Formula: see text]Ti(Zr)[Formula: see text]S2 alloys along the plane with different Ti(Zr) concentrations. The threshold energy values decrease with increasing Ti(Zr) concentrations in the Sn[Formula: see text]Ti(Zr)[Formula: see text]S2 ternary alloys. Moreover, the calculations of formation energy also indicate that these 2D alloys can be fabricated under some experimental conditions. These results suggest that Ti(Zr) substituting Sn atom is an efficient way to tune the band gap and optical properties of 2D SnS2 nanosheets.

Supergravity separation of Pb and Sn from waste printed circuit boards at different temperatures

Printed circuit boards (PCBs) contain many toxic substances as well as valuable metals, e.g., lead (Pb) and tin (Sn). In this study, a novel technology, named supergravity, was used to separate different mass ratios of Pb and Sn from Pb–Sn alloys in PCBs. In a supergravity field, the liquid metal phase can permeate from solid particles. Hence, temperatures of 200, 280, and 400°C were chosen to separate Pb and Sn from PCBs. The results depicted that gravity coefficient only affected the recovery rates of Pb and Sn, whereas it had little effect on the mass ratios of Pb and Sn in the obtained alloys. With an increase in gravity coefficient, the recovery values of Pb and Sn in each step of the separation process increased. In the single-step separation process, the mass ratios of Pb and Sn in Pb–Sn alloys were 0.55, 0.40, and 0.64 at 200, 280, and 400°C, respectively. In the two-step separation process, the mass ratios were 0.12 and 0.55 at 280 and 400°C, respectively. Further, the mass ratio was observed to be 0.76 at 400°C in the three-step separation process. This process provides an innovative approach to the recycling mechanism of Pb and Sn from PCBs.

Keeping Quality of Kareish Chees as Affected with Added Certein Spices and Herbs Oil as Antifungal Agents.

Kariesh cheese was made from pasteurized cow skim milk, acidified by yoghurt starter divided into three equal parts in addition to the control. Three types of spices and herbs oils were added, namely: Nigella (Black cumin) oil, cumin oil and clove oil, 0.5%, 0.75% and 1.0% respectively. Kariesh cheese was analyzed for chemical, microbiological and sensory characteristics when fresh and during refrigerated storage (5±2°C) up to 30 days. Gross composition of the resultant cheese samples was within the Egyptian for kariesh cheese. The pH values were decreased during storage period in control, but all treatments had lower pH values with increase ratios of spices and herbs oils. Kariesh cheese made with yoghurt starter (control) had less total solids, pH values, but an increase in titratable acidity, fat, total protein, SN was detected during storage period. The highest values of SN, TS, fat and total protein were observed in treatments (T2 and T3), and increased during storage period. The total bacterial count (×104) in control (2.65), T1 (2.80, 2.05 and 2.25), T2 (2.60, 2.90 and 2.65) and T3 (2.50, 2.78 and 2.60) and increased gradually during the storage. Coliforms were not detected during storage period, mold and yeast content also were not detected when fresh cheese in control and all treatments, but at the end of the storage period they were lower in all treatments T1 (1.02, 0.76 and 0.35), T2 (0.95, 0.85 and 0.52) T3 (0.80, 0.60 and 0.30) compared to control (1.77). Sensory evaluation of fresh kariesh cheese manufactured by adding 0.75% and 1% oil (T1, T2 and T3) gained higher score for appearance, body and texture and flavor than control at fresh cheese.

Enchanced electrochemical performances of Li4Ti5O12/Sn composites anode via sol-hydrothermal method for lithium ion batteries

Li4Ti5O12 (lithium titanate) were synthesized by sol-gel and hydrothermal method with LiOH as lithium ion source. Li4Ti5O12/Sn composites anode were preparared by ball mill method with three of Sn variation. X-ray diffraction shows spinel, TiO2, and Sn phases with anatase and rutile residue. The lowest electrolyte resistance obtained at the highest Sn value. The specific capacity of battery can be increased from addition of Sn by up to 258.6 mAh/g. Alloying and dealloying reaction of LixSn accomodate the increased specific capacity from charge/discharge. However, Thevolume expansion from LixSn leads to loss of capacity when the C rate increases. The efficient capacity at low and high charge-discharge rate obtained at the highest value of added Sn.

Characterization of glaze ceramics from the archaeological site of La Alcazaba, Almería (Spain)

The Alcazaba de Almería is one of the most impressive mediaeval remains in Al-Andalus. Its defensive walls are expression of the economic and strategic relevance of Almeria City during middle Ages. In the course of archaeological excavations in this monumental area, several glazed ceramic remains were found in the palatine area so-called second enclosure. They are dated back between the 10th and the 15th centuries and correspond to small fragments on which different decorative techniques can be identified: green and manganese, green glazed, cuerda seca total, Nazarí Black and White, lustreware and blue and lustre earthenware. Although only seven samples out of 35 selected samples have been analyzed, their interest lie on that they are the first analytical approach to the ceramics of this important archaeological site and the group is representative some of most typical decorative procedures employed in Al-Andalus.The combination of ion beam and nuclear non-destructive analytical techniques performed on these ceramics have allowed the discussion on several aspects of the production technology, as the use of raw materials, and the degradation processes suffered by them. Glaze composition is discussed first. It is characterized by high values of Pb, Sn, Na, K and Mg. Chromophores are identified and some raw materials are discarded (psilomelane for manganese black) or proposed (absolite, skutterudite and trianite for blue). Secondly, the most degraded samples are found to be characterized by high values of Cl, in an inverse relation with the content of Si. The surface of two samples with lustre decorations, one with Cu particles and one with Cu+Ag particles, are studied finding a progressive decrease of Pb in the surface. Finally, the pastes of the samples are characterized by high values of Ca with respect to other ceramics of the area. Similar values are found in ceramics from Manises and Sevilla. The case of a possible imported sample is also discussed.

Characteristics of fine particulate matter and its sources in an industrialized coastal city, Ningbo, Yangtze River Delta, China

Chemical information is essential in understanding the characteristics of airborne particles, and effectively controlling airborne particulate matter pollution, but it remains unclear in some regions due to the scarcity of measurement data. In the present study, 92 daily PM2.5 (particulate matter with an aerodynamic diameter≤2.5μm) samples as well as historical observation data of air pollutants were collected in urban Ningbo, one of important industrial cities in the coastal area of the Yangtze River Delta, China in autumn and winter (from Nov. 2014 to Feb. 2015). Various chemical species in PM2.5 were determined including water soluble ions, organic and elemental carbon and elements. Positive matrix factorization model, cluster analysis of back trajectories, potential source contribution function (PSCF) model and concentration-weighted trajectory (CWT) model were used for identifying sources, apportioning contributions from each source and tracking potential areas of sources. The results showed the PM2.5 concentration has been reducing; nonetheless, the concentrations of PM2.5 are still much higher than the World Health Organization guideline with high PM2.5 concentrations observed in autumn and winter for the past few years. During the sampling period, the average PM2.5 mass concentration was 77μg/m3 with the major components of OC, NO3−, SO42−, NH4+ and EC, accounting for 24.7, 18.8, 14.5, 11.8 and 6.4% in the total mass concentration, respectively. When the aerosol pollution got worse during the sampling period, the NO3−, SO42− and NH4+ concentrations increased accordingly and NO3− appeared to increase at fastest rate. SO42− transported from industrial areas led to slight difference in spatial distribution of SO42− in Ningbo. More secondary organic carbon was formed and the enrichment factor values of Cu, Ag, Cd, Sn and Pb increased with the degradation of air quality. Ten types of sources were identified for PM2.5 in the autumn and winter of Ningbo, which are metallurgical industry, biomass burning and waste incineration, manufacturing related with Mo, chlor-alkli chemical industry, oil combustion, vehicular emission, secondary source, soil dust, road dust and manufacturing related with Cr, accounting for 9.4, 4.8, 9.4, 7.6, 8.1, 18.7, 27.6, 2, 7.1 and 5.2% of the total sources, respectively. There were five groups of air parcels arriving in Ningbo, of which inland air masses originating from Shandong province were associated with the highest PM2.5 concentrations. Despite the slight differences, it was obvious that the north of Jiangxi, east of Anhui, west of Jiangsu, south of Shandong were identified as major potential sources-areas of SO42−, NO3−, NH4+, Cl−, OC and EC by both PSCF and CWT models.

Assessment and Seasonal Variations of Heavy Metals and Mineral Elements in River Sokoto, North-western Nigeria

The water quality of River Sokoto in North-western Nigeria was monitored from January, April, June, August, September and November, 2014. Analyses of some selected metals and mineral elements namely Na, Mg, K, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Ag, Cd, Sn, Sb, Hg, and Pb from six sampling points was conducted to determine their concentrations in the river during dry (January) and rainy (August) seasons. Analyses of Na and K were carried out using Flame Emission Spectroscopy, while other metals were analysed using Atomic Absorption Spectrophotometry (AAS). The elemental concentrations are generally higher in dry season than in the rainy season. Though Pb was not found in any of the water samples in the dry season, it was found in sample collected from sampling point P4 (a point on stream drainage immediately from Sokoto Cement Factory) at value above WHO’s permissible limit in the rainy season. Ag and Cd were not found in the water samples in rainy season whereas they were found at values above permissible limit in dry season. Hg was found at value above permissible limit in both seasons. The result of T-test analysis shows there was highly significant difference (p≤0.01) in the values of Mg, K, Cr, Fe, Co, Ag, Cd, Sn and Hg in all samples for dry and rainy seasons. High level of Cr, Co, Ag, Cd, Hg and Pb in River Sokoto above WHO’s permissible limit will certainly have adverse effect on the health of the residents. Keywords : Seasonal variation, heavy metals, mineral elements, pollution, River Sokoto.