Maximum Ni Concentrations Research Articles

Heavy metal concentrations in fishes from Zakrzówek Reservoir and the Vistula River near Kraków: Human risk assessment

Abstract The aim of this study was to compare tissue concentrations of heavy metals (copper (Cu), manganese (Mn), iron (Fe), nickel (Ni), zinc (Zn)) in roach (Rutilus rutilus (L.)), chub (Squalius cephalus (L.)), and bleak (Alburnus alburnus (L.)) from two locations on the Vistula River upstream from Kraków and Zakrzówek Reservoir, a former limestone quarry flooded over 30 years ago that is located close to the center of Kraków. The findings showed that heavy metal concentrations in fishes from the Vistula River upstream from Kraków were higher compared to those in fishes from Zakrzówek Reservoir. The highest heavy metal concentrations were found in hard tissues, such as bone and scales, and the lowest was in muscle tissue. Metal pollution index (MPI), estimated daily intake (EDI), target hazard quotient (THQ), and hazard index (HI) analyses showed no significant non-carcinogenic risk to human health from the consumption of the muscle meat of the fishes analyzed. Cancer risk (CR) values, calculated based on maximum Ni concentrations in fish muscle tissue, did not exceed the upper limit of the acceptable cancer risk range. The findings show that the assessment of heavy metal contamination of fishes should be continued and extended to include other water bodies used for fishing and other xenobiotics that accumulate in fishes and may pose risks to human health.

Seed Priming Improved Antioxidant Defense System and Alleviated Ni-Induced Adversities in Rice Seedlings Under N, P, or K Deprivation.

Excess nickel (Ni) concentration in the growing medium severely hampers the plant growth by disturbing oxidative metabolism and nutrient status. The present study was carried out to investigate the individual and interactive effects of Ni toxicity (0.25 mM NiSO4.6H2O) and nutrient deprivation (no-N, no-P, or no-K) on growth, oxidative metabolism, and nutrient uptake in primed and non-primed rice seedlings. Rice seed was primed with distilled water (hydropriming), selenium (5 mg L-1), or salicylic acid (100 mg L-1). The Ni toxicity and deprivation of N, P, or K posed negative effects on the establishment of rice seedlings. The shoot length and fresh biomass were severely reduced by Ni toxicity and nutrient stresses; the minimum shoot growth was recorded for rice seedlings grown under Ni toxicity and no-N stress. The Ni toxicity reduced the root fresh biomass but did not significantly affect the root length of N-deprived seedlings. The rice seedlings with no-P or no-K recorded similar root fresh biomass compared with those grown with sufficient nutrient supply. The Ni toxicity alone or in combination with nutrient stresses triggered the production of reactive oxygen species (ROS) and caused lipid peroxidation in rice seedlings. Among antioxidants, only glutathione reductase and vitamin E were significantly increased by Ni toxicity under different nutrient stress treatments. The Ni toxicity also reduced the concentrations of N particularly in shoot of rice seedlings. The N-deprived (no-N) seedlings recorded maximum Ni concentration in shoot, while K-deprived (no-K) seedlings showed higher Ni concentrations in root. Seed priming with selenium or salicylic acid was effective to alleviate the detrimental effects of Ni toxicity and/or nutrient stresses on rice seedlings. The better growth and greater stress tolerance of primed seedlings was coordinately attributed to lower ROS production, higher membrane stability, strong antioxidative defense system, and maintenance of mineral nutrient status.

Controlling factors on nickel uptake by plants growing on Ni-laterites: A case study in biogeochemical exploration from the Mazayejan area, SW Iran

Nickel bearing soils derived from serpentinized ultramafic rocks are widely exposed as two parallel zones in Bavanat region along the Sedimentary Zagros Orogenic (SZO) and Metamorphic Sanandaj-Sirjan (MSS) belts. These laterites in the Mazayejan area of the Northern zone are divided into two groups; the in situ soils found mainly in the east, and the transported soils which are common in the west of the study area. The maximum Ni concentration of the studied soils is 1787 μg g−1. The main vegetation types of the area include open shrub lands and semi-desert steppes. Many soil characteristics in the study area are quite variable, such as Mg/Ca ratio, exchangeable metal fraction, extraction efficiency (EF), pH, organic content (OM), texture, and cation exchange capacity (CEC) as well as seasonal variation of Ni availability and metal transfer to plants. This study indicated that low Mg/Ca ratio (0.1–2.3 μg g−1), high carbonate content (up to 42.8 wt%) and very low exchangeable Ni fraction (0.01–0.34 μg g−1) result in low uptake of nickel by plants. Low EF, but high pH and OM result in Ni fixation in the soils, and consequently low Ni transfer factor to plants. Clay textured soils with high CEC (10.5 wt%) are characterized by the lowest transfer coefficient of Ni from soil to plant, due to the stronger adsorption of Ni in the soils. Ni concentration in living tissues change with the season, the leaves of the same plants investigated in autumn contain more Ni than in spring. As a result, plant sampling in autumn should be preferred for nickel exploration when using biogeochemical and other methods such as Ni phytoextraction, by selected plants.

Assessment of Zinc and Nickel Profile of Vegetables Grown in Soil Irrigated with Sewage Water

The current investigation assessed the nickel and zinc contents of the soil, and the vegetables grown in wastewater irrigated areas. Atomic Absorption Spectrophotometer (AA-6300 Shimadzu Japan) assessed the metal profile of the samples. The mean concentrations of metals in soil samples varied from O.O85 to 1.611 mg/kg for Ni and O.453 ~ O.9O8 mg/kg for Zn. In vegetables, the maximum Ni concentration was observed in Capsicum baccatum consequent to wastewater irrigation, while its minimum concentrations were noticed in Capsicum frutescens after canal water irrigation. Sewage water irrigation resulted in the highest Zn contents in Solanum lycopersicum and the lowest Zn contents were noticed in Capsicum baccatum after canal water irrigation. The daily intake values of Ni and Zn were higher caused by sewage water irrigation as compared to the canal water irrigation in all tested vegetable samples. Health risk index (HRI) values for Ni and Zn accumulation in vegetables fell within the permissible limit in Pakistan and these were regarded as appropriate for human intake.

Dopant incorporation in ultrasmall quantum dots: a case study on the effect of dopant concentration on lattice and properties of SnO2 QDs

Although impurity doping of nanocrystals is essential in controlling their properties for various applications, but the doping mechanism of ultrasmall semiconductor QDs is not yet understood. In this study, the effect of concentration of Ni2+ ions on the lattice and properties of 1.4 nm SnO2 QDs, prepared via chemical-precipitation route has been studied in detail. The quantum dot lattice contracted at maximum Ni concentration of 10% due to the incorporation of Ni ions at the substitutional sites on the surface of SnO2 lattice, while it began to expand gradually as the Ni concentration was further decreased from 10 to 1%, due in part to the Ni ions located in the core of the host lattice, occupying interstitial sites between Sn and O atoms leading to the expansion of the lattice with the decrease in the amount of strain and dislocation density. High resolution transmission electron microscopy confirms the presence of such dislocations in pure and doped SnO2 QDs. Optical investigation shows that the Ni doping in SnO2 lattice leads to a blue shift in the absorption wavelength. The concentration quenching effect of the PL emission with Ni doping is explained in detail. An enhancement in the photocatalytic activity has been achieved with optimum Ni incorporation in SnO2. The work also successfully correlates photoluminescence quenching and enhanced photocatalytic activity with the defect production happened in SnO2 system on Ni doping.

Uptake of nickel by synthetic mackinawite

The uptake of aqueous Ni(II) by synthetic mackinawite (FeS) was examined in anaerobic batch experiments at near-neutral pH (5.2 to 8.4). Initial molar ratios of Ni(II) to FeS ranged from 0.008 to 0.83 and maximum Ni concentrations in mackinawite, expressed as the cation mol fraction, were as high as XNi=0.56 (Fe1−xNixS; 0≤x≤1). Greater than 99% Ni removal from solution occurred when Ni loading remained below 0.13±0.03 (1σ) mol Ni per mol FeS due to sorption of Ni at the mackinawite surface. Characterization of experimental solids using X-ray diffraction and Raman spectroscopy showed patterns characteristic of nanocrystalline mackinawite; no evidence of nickel monosulfide (α-NiS or millerite), polydymite (Ni3S4), or godlevskite [(Ni,Fe)9S8] formation was indicated regardless of the amount of Ni loading. Slight expansion of the c-axis correlated with increasing Ni content in synthetic mackinawite, from c=5.07±0.01Å at XNi=0.02 to c=5.10±0.01Å at XNi=0.38.Ni K-edge extended X-ray absorption fine structure (EXAFS) spectra of synthetic Ni-bearing mackinawite are similar in phase and amplitude to the Fe K-edge EXAFS spectrum of Ni-free mackinawite, indicating that the molecular environment of Ni2+ in Ni-bearing mackinawite is similar to that of Fe2+ in Ni-free mackinawite. EXAFS data fitting of Ni-bearing mackinawite with XNi=0.42 indicated a coordination number of 4.04±0.30 and an average NiS bond distance of 2.28Å, in good agreement with the FeS bond distance of 2.26Å in mackinawite, tetrahedral Fe coordination, and slight lattice expansion along the c-axis. At lower Ni loadings (XNi=0.05–0.11), EXAFS analysis showed a decrease in NiS coordination towards CN=3, which reflects the influence of sorbed Ni. Continued Ni uptake, past the maximum amount of sorption, was accompanied by proportional molar release of Fe to solution. Interstitial occupancy of Ni within the mackinawite interlayer may be transitional to structural substitution of Fe.The Ni-mackinawite solid-solution is described by a one-site binary mixing model:lnKd=lnKe−WRT1−2XNiwhere Kd is the distribution coefficient, Ke is the ratio of equilibrium constants for Ni-mackinawite and mackinawite (14.4±1.3), W is an ion interaction parameter, and XNi is the mole fraction of end-member NiS in the solid solution. The experimentally determined value of W is 17.74±1.15kJ/mol and indicates significant non-ideality of the solid solution.Transformation processes were evaluated by aging Ni-mackinawite with polysulfides and solutions saturated with air. Reaction of Ni-mackinawite with polysulfides led to the formation of pyrite (FeS2) and Ni retention in the solid phase. When Ni-mackinawite was aged in the presence of dissolved oxygen, transformation to goethite (FeOOH) and violarite (FeNi2S4) was observed.

Identification of clear taenite in meteorites as ordered FeNi

In the Fe–Ni system, the face-centred cubic (f.c.c.) phase (called taenite in meteorites) is stable for all compositions above 1,185 K. Below this temperature, the body-centred cubic phase (kamacite) is stable and has a maximum Ni concentration of about 7% around 720 K (ref. 1). Metal in meteorites is commonly found to contain kamacite with 4–7% Ni and taenite with 20–45% Ni. Taenite grains have M-shaped Ni profiles which formed on slow cooling during diffusion-controlled growth of kamacite and preserve a record of the cooling rates. Another Fe–Ni phase with 49–57% Ni was found in ordinary chondrites by Taylor and Heymann2 and identified as a variety of taenite. They called it clear taenite to distinguish it from the zoned variety, which develops cloudy borders on etching with acid, and proposed that it nucleated at 660–610 K on the edge of isolated kamacite grains. We report here studies of meteoritic metal with reflected-light microscopy and electron-probe analysis, in which we discovered that clear taenite is optically anisotropic and we have found it in all meteorite groups. We use the term clear taenite as originally defined to include only alloys with ∼48–57% Ni, not those with ∼25–30% Ni, which Lin et al.3 called clear taenite II. Except for cloudy taenite which contains ∼30–40% Ni and looks cloudy because it is a submicroscopic two-phase mixture, taenite remains clear on etching. We conclude that clear taenite is the ordered, tetragonal FeNi phase found by Albertsen et al.4–6 in two iron meteorites using Mossbauer and X-ray techniques, and that it formed from taenite, not kamacite. This tetragonal phase has been synthesised by irradiating FeNi alloys with neutrons or electrons below 593 K (refs 7,8).