Fraction Of Se Research Articles

Influence of Long-Term Fertilization on Selenium Accumulation in Soil and Uptake by Crops

Continuous applications of organic and inorganic fertilizers can affect soil and food quality with respect to selenium (Se) concentrations. A long-term (over 20 years) experimental field study, started in 1989, was conducted to investigate the changes in soil Se fractions and its uptake by crops, as affected by different fertilizer practices, in the North China Plain with an annual crop rotation of winter wheat and summer maize. The long-term experiment was arranged in a complete randomized block design consisting of 4 replications with 7 fertilizer treatments: 1) organic compost (OC), 2) half organic compost plus half N-P-K chemical fertilizers (OC + NPK), 3) N-P-K fertilizers (NPK), 4) N-P fertilizers (NP), 5) P-K fertilizers (PK), 6) N-K fertilizers (NK), and 7) an un-amended control. Soil samples from the surface (20 cm) were collected in 1989, 1994, 1999, 2004 and 2009 to characterize Se and other soil properties. In 2009, the average soil Se concentrations in the treatments (149 ± 8 pg kg−1) were higher than those in the soil samples collected in 1989 at the beginning of the experiment (112 ± 4 pg kg−1), and decreased in the order of OC > OC + NPK > NPK ≈ NP > PK ≈ NK > control. Sequential extraction showed the oxidizable fraction (50.06% ± 3.94%) was the dominant form of Se in the soil, followed by the residual fraction (24.12% ± 2.89%), exchangeable fraction (15.09% ± 4.34%) and Fe-Mn oxides fraction (10.73% ± 4.04%). With an increase of soil K, the exchangeable Se concentrations in the soil increased. The Se concentrations in the soil tillage layer (0–20 cm) were mainly related to soil organic carbon (SOC), although different contributions came from atmospheric deposition, irrigation and fertilizers. With the accumulation of SOC, the uptakes of soil Se by two crops were inhibited. For the OC and OC + NPK treatments, Se concentrations in wheat grains were lower than the critical standard of Se in stable food (100 µg kg−1). Additionally, Se concentrations in grains were also decreased by the deficiencies of major soil nutrients, especially P.

Effects of aging on the fraction distribution and bioavailability of selenium in three different soils.

Aging refers to the processes by which the mobility and bioavailability of metals in soil decline with time. Although long-term aging is a key process that needs to be considered in risk assessment of metals, few investigations has been attempted to determine whether and how residence time influences the selenium (Se) fractions and bioavailability in soil. In this study, the fractions of Se in soils was evaluated, and bioavailability were assessed by measuring Se concentration in pak choi (Brassica chinensis L.). Results showed that the change of soil available Se in all tested soils divided into two phases: rapid decrease at the initial time (42 d) and slow decline thereafter. The second-order equation could describe the decrease processes of available Se in tested soils during the entire incubation time (R(2) > 0.99), while parabolic diffusion equation had less goodness of fit. Those results indicated that Se aging was controlled not only by diffusion process but also by other processes such as nucleation/precipitation, adsorption/desorption with soil component, occlusion by organic matter and reduction reaction. Soil available Se fractions tended to transform to more stable fractions during aging. The changes of Se concentration in pak choi were consistent with the variation in soil available Se content. In addition, 21 d could be reference for the time of Se aging reaching stabilization in krasnozems and fluvo-aquic soil, and 30 d for black soil. Results could provide theoretical basis to formulate environmental quality criterion and choose the equilibrium time before implementing a pot experiment in Se-spiked soils.

Selenium speciation and extractability in Dutch agricultural soils

The study aimed to understand selenium (Se) speciation and extractability in Dutch agricultural soils. Top soil samples were taken from 42 grassland fields and 41 arable land fields in the Netherlands. Total Se contents measured in aqua regia were between 0.12 and 1.97mgkg–1(on average 0.58mgkg–1). Organic Se after NaOCl oxidation-extraction accounted for on average 82% of total Se, whereas inorganic selenite (selenate was not measurable) measured in ammonium oxalate extraction using HPLC–ICP-MS accounted for on average 5% of total Se. The predominance of organic Se in the soils is supported by the positive correlations between total Se (aqua regia) and total soil organic matter content, and Se and organic C content in all the other extractions performed in this study. The amount of Se extracted followed the order of aqua regia>1M NaOCl (pH8)>0.1M NaOH>ammonium oxalate (pH3)>hot water>0.43M HNO3>0.01M CaCl2. None of these extractions selectively extracts only inorganic Se, and relative to other extractions 0.43M HNO3 extraction contains the lowest fraction of organic Se, followed by ammonium oxalate extraction. In the 0.1M NaOH extraction, the hydrophobic neutral (HON) fraction of soil organic matter is richer in Se than in the hydrophilic (Hy) and humic acid (HA) fractions. The organic matter extracted in 0.01M CaCl2 and hot water is in general richer in Se compared to the organic matter extracted in 0.1M NaOH, and other extractions (HNO3, ammonium oxalate, NaOCl, and aqua regia). Although the extractability of Se follows to a large extent the extractability of soil organic carbon, there is several time variations in the Se to organic C ratios, reflecting the changes in composition of organic matter extracted.

Do selenium hyperaccumulators affect selenium speciation in neighboring plants and soil? An X-Ray Microprobe Analysis

Neighbors of Se hyperaccumulators Stanleya pinnata and Astragalus bisulcatus were found earlier to have elevated Se levels. Here we investigate whether Se hyperaccumulators affect Se localization and speciation in surrounding soil and neighboring plants. X-ray fluorescence mapping and X-ray absorption near-edge structure spectroscopy were used to analyze Se localization and speciation in leaves of Artemisia ludoviciana, Symphyotrichum ericoides and Chenopodium album growing next to Se hyperaccumulators or non-accumulators at a seleniferous site. Regardless of neighbors, A. ludoviciana, S. ericoides and C. album accumulated predominantly (73–92%) reduced selenocompounds with XANES spectra similar to the C-Se-C compounds selenomethionine and methyl-selenocysteine. Preliminary data indicate that the largest Se fraction (65–75%), both in soil next to hyperaccumulator S. pinnata and next to nonaccumulator species was reduced Se with spectra similar to C-Se-C standards. These same C-Se-C forms are found in hyperaccumulators. Thus, hyperaccumulator litter may be a source of organic soil Se, but soil microorganisms may also contribute. These findings are relevant for phytoremediation and biofortification since organic Se is more readily accumulated by plants, and more effective for dietary Se supplementation.

Drying effects on selenium and copper in 0.01 M calcium chloride soil extractions

The study aimed to understand the effects of drying and rewetting the soils on soluble selenium (Se) and copper (Cu) concentrations in 0.01M CaCl2 soil extraction, and the mechanisms leading to these changes. Soluble Se and Cu concentrations were measured in the extractions of 58 soil samples taken from grassland and arable land in The Netherlands before and after oven drying at 40°C. Selenium speciation and dissolved organic matter (DOM) fractionation were performed using Donnan membrane technique (DMT) and DAX-8 resin. Drying and rewetting the soils increased soluble Se and Cu concentrations in CaCl2 extraction. The increase of both elements was associated with the increase of dissolved organic carbon (DOC). Compared to the magnitude of DOC increase (1.3 to 11 fold), the increase of soluble Se (1.3 to 34 fold) was more pronounced, whereas the increase of soluble Cu (1.1 to 4.6 fold) was less strong. The DMT analysis confirmed the dominance of colloidal sized DOM-associated Se both in the moist and dried soil extractions, showing that the colloidal sized organic Se is mainly responsible for the increase of total soluble Se upon drying. The Se to DOC ratio increased upon drying in most of the soils, indicating enrichment of Se in DOM after drying. No consistent difference in Se to DOC ratio was found between the fulvic acids (FA) and hydrophilic (Hy) fraction of DOM after drying. Fractionation of DOM showed that Hy and FA fraction accounted for respectively 74% and 26% of total DOC in the dried soils, which corresponds to the Se fraction in Hy and FA of DOM. The decrease of SUVA (0.3 to 1.0 fold) after drying implied a decrease of FA:Hy ratio in DOM and a decrease of average DOM aromaticity. Upon drying, a positive correlation between the change of Cu loading on DOC (Cu:DOC ratio) and the change of aromaticity (SUVA) of DOM was found, showing that the increase of Cu complexed with (mainly) aromatic DOM explains soluble Cu increase upon drying. The decrease of Cu loading on DOC upon drying was attributed to a decrease of the aromaticity and affinity to Cu of the DOM. Colloidal sized organic Se and Cu–DOM complex are the major species of Se and Cu, respectively, in the extractions of moist and dried soils, which may not directly be available for plant uptake.

The Content of Silver, Cobalt, Chromium, Iron, Mercury, Rubidium, Antimony, Selenium, and Zinc in Malignant Giant Cell Tumor of Bone

Background and Purpose: The changes of trace element contents and trace element relationships in malignant giant cell tumor of bone (GCTB) in a comparison with normal bone tissue were investigated using a non-destructive neutron activation analysis with high resolution spectrometry of long-lived radionuclides. Materials and Methods: The silver (Ag), cobalt (Co), chromium (Cr), iron (Fe), mercury (Hg), rubidium (Rb), antimony (Sb), selenium (Se), and zinc (Zn) content and Co/Ag, Cr/Ag, Fe/Ag, Hg/Ag, Sb/Ag, Se/Ag, Co/Rb, Cr/Rb, Fe/Rb, Hg/Rb, Sb/ Rb, Se/Rb, Co/Zn, Cr/Zn, Fe/Zn, Hg/Zn, Sb/Zn, and Se/Zn ratios were estimated in normal bone samples from 27 patients with intact bone (12 females and 15 males, aged from 16 to 49 years) and in tumor samples, obtained from open biopsies or after operation of 8 patients with malignant GCTB (3 females and 5 males, 14 to 56 years old). The reliability of difference in the results between intact bone and malignant GCTB was evaluated by Student’s t-test. Results: It was found that in malignant GCTB tissue the mass fractions of Co, Fe, Sb, and Se are significantly higher and the mass fraction of Rb is lower than in normal bone tissues. Moreover, it was shown that significantly higher Fe/Ag, Se/ Ag, Se/Rb, Co/Zn, Fe/Zn, Hg/Zn, Sb/Zn, Se/Zn mass fraction ratios are typical of the malignant GCTB tissue compared to intact bone. In malignant GCTB tissue many correlations between trace elements found in the control group was no longer evident. Conclusions: Finally, it was concluded that in malignant transformed bone tissues a trace element metabolism is significantly disturbed. The studies on the role of trace elements in the etiology of malignant GCTB and the usefulness of trace elements as bone tumor markers have to be continued.

The Content of Silver, Cobalt, Chromium, Iron, Mercury, Rubidium, Antimony, Selenium, and Zinc in Osteogenic Sarcoma

Objectives: To clarify the role of trace elements in the etiology and the pathogenesis of the osteogenic sarcoma (osteosarcoma), a non-destructive neutron activation analysis with high resolution spectrometry of long-lived radionuclides was performed. Methods: The silver (Ag), cobalt (Co), chromium (Cr), iron (Fe), mercury (Hg), rubidium (Rb), antimony (Sb), selenium (Se), and zinc (Zn) mass fraction, Rb/Co, Rb/Fe, Rb/Se, and Rb/Zn mass fraction ratios as well as Co × Zn, Fe × Zn, Sb × Zn, Se × Zn, Co × Se, and Fe × Se mass fraction multiplications were estimated in normal bone samples from 27 patients with intact bone (12 females and 15 males, aged from 16 to 49 years), who had died from various non bone related causes, mainly unexpected from trauma, and in tumor samples, obtained from open biopsies or after operation of 27 patients with osteosarcoma (9 females and 18 males, 6 to 71 years old). The reliability of difference in the results between intact bone and osteosarcoma tissues was evaluated by Student’s t-test. Results: In the osteosarcoma tissue the mass fractions of Co, Cr, Fe, Sb, Se, and Zn are significantly higher while the mass fraction of Rb is lower than in normal bone tissues. Moreover, we found significantly lower values of Rb/Co, Rb/Fe, Rb/Se, and Rb/Zn mass fraction ratios as well as significant higher mean values of Co × Zn, Fe × Zn, Sb × Zn, Se × Zn, Co × Se, and Fe × Se mass fractions multiplications in the osteosarcoma tissue compared to intact bone. In the osteosarcoma tissue many correlations between trace elements found in the control group were no longer evident. Conclusion: In osteosarcoma transformed bone tissues the trace element homeostasis is significantly disturbed.

Differences between chemical element contents in hyperplastic and nonhyperplastic prostate glands investigated by neutron activation analysis.

In order to clarify the differences between Ag, Br, Ca, Co, Cr, Fe, Hg, K, Mg, Mn, Na, Rb, Sb, Sc, Se, and Zn contents in hyperplastic (patients with benign prostate hyperplasia (BPH), n = 32) and nonhyperplastic (control group of healthy male inhabitants, n = 32) prostates, an instrumental neutron activation analysis was performed. Mean values (M ± SΕΜ) for mass fraction (mg/kg, dry mass basis) of chemical elements in glands of patients with BPH were the following: Ag, 0.0346 ± 0.0060; Br, 30.4 ± 3.6; Ca, 2030 ± 165; Co, 0.0716 ± 0.0097; Cr, 1.073 ± 0.119; Fe, 130.0 ± 7.9; Hg, 0.232 ± 0.030; K, 14,470 ± 740; Mg, 1200 ± 80; Mn, 1.19 ± 0.09; Na, 11,610 ± 870; Rb, 14.7 ± 0.8; Sb, 0.163 ± 0.025; Sc, 0.0257 ± 0.0040; Se, 1.243 ± 0.079; and Zn, 1235 ± 92. It was observed that in BPH tissue, the mass fraction of Co (p < 0.015), Cr (p < 0.0002), Hg (p < 0.000007), K (p < 0.001), Rb (p < 0.048), Sb (p < 0.0001), and Se (p < 0.000001) were significantly higher than in controls. In the sixth to eighth decades, the mass fractions of almost all chemical elements in hyperplastic prostates did not depend from age. Our finding of correlation between pairs of prostatic chemical element mass fractions indicates that there is a great disturbance of prostatic chemical element relationships with a benign hyperplastic transformation. The results apparently confirm the disturbed homeostasis of Zn and Se and some other chemical elements in the etiology of BPH.

Chlorine leaching of Au from copper anode slimes using the response surface method in an agitated reactor

The response surface methodology (RSM) was employed to study the interactions among different factors (i.e. temperature, liquid to solid ratio, HCl concentration and chlorine gas flowrate) involved in the leaching of Au from copper anode slimes. The interactions such as liquid to solid ratio, chlorine gas flowrate×temperature and HCl concentration×temperature were found to be statistically significant. Under the optimum operational conditions of Cl2 = 1·99 L min−1, 10 000/T = 28·7 K−1, L/S = 12·57 L kg−1, HCl = 2·74 mol L−1 in a semi-pilot 3-L agitated reactor, the maximum recovery achieved for Au was around 93% using the second polynomial equation. This led to a selectivity factor (i.e. the ratio of ‘Au reaction fraction’ to the sum of ‘Se and Cu reaction fractions’) of 86. Process optimisation was carried out based on the maximum selectivity factor achieved. This resulted in the following optimum conditions: Cl2 = 1·26 L min−1, 10 000/T = 30·83 K−1, L/S = 5 L kg−1 and HCl = 2·66 mol L−1, with a separation factor of 112.

Effect of applied sulphur on the uptake by wheat of selenium applied as selenite

This study examined the effect of sulphur (S) on the transformation of selenium (Se) fractions and Se species in soil and on the uptake by wheat of Se applied as selenite. Pot and hydroponic experiments were conducted at the wheat seedling stage. The Se concentrations in shoots and roots of wheat and soil were analyzed by HG-AFS-8220. Selenium content in the soil was divided into different fractions and species. The application of 150 mg∙kg−1 S reduced Se concentrations in wheat shoots and roots significantly, declining 47 % and 45 %, respectively. Sulphur treatment changed soil pH (maximum decrease of 0.52 units) and organic matter content (maximum increase of 0.96 g∙kg−1) significantly, thereby reduced the soluble Se concentration, increased the iron (Fe)/manganese (Mn) oxide-bound Se concentration. Sulphur treatment also reduced the concentration of Se6+ in the exchangeable fraction. The application of S fertiliser promoted soluble Se transformation to Fe-Mn oxide-bound Se, organic matter-bound Se and residual Se by lowering soil pH and increasing organic matter content, and inhibited the transformation of Se4+ to Se6+ in the exchangeable fraction, hence reducing wheat uptake of Se in high-Se areas.

Bioaccessibility and content of Se in fish and shellfish widely consumed in Mediterranean countries: influence of proteins, fat and heavy metals

Twenty samples of fish and seafood products were selected for determination of total and bioaccessible Se (i.e. soluble and dialyzable). The Se contents ranged between 0.638–0.052 µg/g. The samples of fatty fish such as mackerel and tuna showed higher contents than the species of lean fish, and mainly the fresh water fish, such as salmon, trout and panga showed the lowest contents. The fraction of soluble Se ranged between 43–84% while that the fraction of dialyzable Se did not exceed 14%. No statistically significant correlation was observed between protein content and total and bioaccessible Se content. In contrast, a negative interaction was observed between bioaccessible Se and fat content, and between bioaccessible Se and presence of heavy metals like Cd.

Selenium and tellurium fractionation, enrichment, sources and chronological reconstruction in the East China Sea

Surface and core sediments of the East China Sea (ECS) were collected to study spatio-temporal distributions and chemical fractions of Se and Te and to evaluate their enrichment and sources. Higher Se and Te concentrations in surface sediments appeared in the inner shelf and near the Cheju Island. It seemed to be controlled by sources and sediment characteristics. Enrichment factors (EFs) showed that Se and Te were at minor and moderate enrichment, respectively. Sequential extraction suggested that non-residual fractions of Se and Te accounted for high percentages (29.5 ± 16.2% and 50.9 ± 13.2%) in total, combined with risk assessment code (RCA), indicating that Se and Te were at medium and high risks, respectively. All temporal profiles of abundances, EFs and burial fluxes (BFs) of Se and Te displayed higher values before 1900, in 1989 and 2009, and in the period of 1960–1980 with a peak in 1970. These higher values were closely associated with biological and anthropogenic activities.

INAA application in the assessment of Ag, Co, Cr, Fe, Hg, Rb, Sb, Sc, Se, and Zn mass fraction in pediatric and young adult prostate glands

The effect of age on trace element contents in intact prostate of 50 apparently healthy 0–30 year old males was investigated by neutron activation analysis with high resolution spectrometry of long-lived radionuclides. Mean values (M ± SEΜ) for mass fraction (milligram per kilogram, on dry-weight basis) of trace elements were: Ag 0.0708 ± 0.0096, Co 0.0348 ± 0.0040, Cr 0.466 ± 0.069, Fe 100 ± 10, Hg 0.0258 ± 0.0025, Rb 12.6 ± 0.8, Sb 0.0576 ± 0.0066, Sc 0.0125 ± 0.0016, Se 0.478 ± 0.031, and Zn 273 ± 31, respectively. A strongly pronounced tendency of age-related increase in Se and Zn mass fraction and of age-related decrease in Co, Cr, Fe, and Sc mass fraction was observed in period of life from 0 to 30 years.

Selenium Bioaccessibility and Bioavailability in Se-Enriched Food Supplements

Most European people have selenium (Se) intake inferior to recommended values that are considered necessary to ensure the beneficial action of antioxidant selenoproteins. People could therefore tend to have recourse to Se-enriched food supplements (FS) aiming to increase their Se body level. On the Belgian market, three main types of Se-rich FS are available: Se-enriched yeast, selenate-based FS, and selenite-based FS. In the present work, in vitro tests imitating gastrointestinal digestion and intestinal absorption were used to determine the bioaccessible and bioavailable fractions of Se present in one specimen of each category of FS. The aim of the study was to verify to which extent the difference in Se speciation could influence the efficiency of FS for enhancing the human Se status. Results indicated that differences exist in both bioaccessibility and bioavailability between the three types of FS, and that these differences could be related, at least partially, to the Se species profile. Overall bioavailability of the three FS was low (maximum 14 % of the original Se content). Among the three samples, the selenate-based FS produced the highest fraction of bioavailable Se, followed by Se-yeast, and finally by the selenite-based FS for which Se was almost not available at all. These results confirm the low availability of inorganic Se but were somewhat unexpected regarding the yeast-based FS since Se-rich yeasts are usually reported to contain an important fraction of available Se.

Use of Neutron Activation Analysis and Inductively Coupled Plasma Mass Spectrometry for the Determination of Trace Elements in Pediatric and Young Adult Prostate

The questions about the androgen control and the involvement of trace elements in prostatic reproductive function still remain unanswered. One valuable way to elucidate the situation is to compare the values for the prostatic mass fractions of trace elements in pre-and post-pubertal boys. The effect of age on the mass fraction of 54 trace elements in intact prostate of 50 apparently healthy 0-30 years old males was investigated by neutron activation analysis and inductively coupled plasma mass spectrometry. Mean values (M ± SΕΜ) for mass fraction (milligram per kilogram, on dry-weight basis) of trace elements were: Ag 0.062 ± 0.008, Al 80 ± 18, Au 0.0092 ± 0.0024, B 5.9 ± 3.5, Be 0.0034 ± 0.0009, Bi 0.018 ± 0.010, Br 26 ± 3, Cd 0.26 ± 0.05, Ce 0.049 ± 0.012, Co 0.035 ± 0.004, Cr 0.49 ± 0.07, Cs 0.036 ± 0.005, Dy 0.0072 ± 0.0018, Er 0.0040 ± 0.0011, Fe 100 ± 10, Gd 0.0065 ± 0.0018, Hg 0.031 ± 0.004, Ho 0.0013 ± 0.0004, La 0.034 ± 0.007, Li 0.064 ± 0.009, Mn 1.69 ± 0.15, Mo 0.54 ± 0.13, Nb 0.013 ± 0.004, Nd 0.025 ± 0.006, Ni 4.1 ± 0.6, Pb 1.3 ± 0.2, Pr 0.0058 ± 0.0015, Rb 14.5 ± 0.8, Sb 0.051 ± 0.006, Sc 0.013 ± 0.002, Se 0.54 ± 0.03, Sm 0.0055 ± 0.0015, Sn 0.22 ± 0.05, Tb 0.0012 ± 0.0004, Th 0.0076 ± 0.0020, Ti 2.8 ± 0.5, Tl 0.0032 ± 0.0009, Tm 0.00064 ± 0.00017, U 0.0025 ± 0.0004, Y 0.036 ± 0.010, Yb 0.0037 ± 0.0012, Zn 281 ± 32, and Zr 0.16 ± 0.04. The upper limit of mean mass fraction of As, Eu, Ga, Hf, Ir, Lu, Pd, Pt, Re, and Ta were: As ≤ 0.069, Eu ≤ 0.0012, Ga ≤ 0.071, Hf ≤ 0.049, Ir ≤ 0.00054, Lu ≤ 0.00063, Pd ≤ 0.014, Pt ≤ 0.0029, Re ≤ 0.0048, and Ta ≤ 0.010. This work revealed that there is a significant tendency for the mass fractions of Cd, Se and Zn in the prostate tissue of healthy individuals to increase with age from the time of birth up to 30 years. It was also shown that high levels of Al, Au, B, Br, Cr, Ga, Li, and Ni mass fraction in prostate tissue do not indicate a direct involvement of these elements in the reproductive function of prostate.

ICP-MS for the determination of selenium bioavailability from seafood and effect of major food constituents

In-vitro bioavailability of Se has been assessed in different raw seafood and edible seaweed samples by using a simulated gastric and intestinal digestion/dialysis method. Correlations between Se bioavailability and food nutrients content have also been established. Low dialyzability percentages of Se have been found for fish and mollusk samples (6.7±3.4 and 5.5±2.4%, respectively). However, high dialyzability percentages (within the 66.7±31.1% range) have been found for seaweed. Se bioavailability exhibits a positive correlation with the carbohydrate content and with the dietary fiber. Negative correlation was obtained with the protein content. Finally, no correlation has been observed between the bio-available fraction of Se and the fat content of the studied samples.

Online Preconcentration-IC-ICP-MS for Selenium Quantification and Speciation at Ultratraces

Selenium (Se) is of key importance to human health with a very narrow concentration range of optimal dietary intake. Due to the inherent analytical challenge linked with the low natural abundance, information on precise and accurate Se speciation in deficient environments is hardly existent. This study presents a novel approach to determine Se species-specifically at ultratraces, by online coupling of a preconcentration (trap) column to an ion chromatography inductively coupled plasma mass spectrometry (IC-ICP-MS) system. It is demonstrated that with this robust and work/time efficient method, the predominant selenium oxyanions, selenite (Se(IV)) and selenate (Se(VI)), can be quantified down to 7.3 and 8.3 picogram total Se, respectively, in an overall analytical time of 420 s, only. The applicability for environmental samples was proven on pristine volcanic ashes collected from seven different volcanoes. The high sensitivity of the novel approach allowed to determine speciation in samples that were strongly depleted in total selenium (<0.05 mg kg(-1) Se) with only minor fractions of Se mobilized (i.e., less than 10% of the total selenium was leached in 10 out of 12 samples). The studied samples showed considerate differences in selenium speciation, with selenite and selenate co-occurring in most samples. The fact that the studied sample leachates had a wide range of pH (3.78-9.55) and major anion/cation composition underlines the versatility and wide potential application range of the method presented.

Quantitative analysis of Cu(In,Ga)Se2 thin films by secondary ion mass spectrometry using a total number counting method

The relative atomic fraction of Cu(In,Ga)Se2 (CIGS) films is one of the most important measurements for the fabrication of CIGS thin film solar cells. However, the quantitative analysis of multi-element alloy films is difficult by surface analysis methods due to the severe matrix effect. In this study, the quantitative analysis of CIGS films was investigated by secondary ion mass spectrometry (SIMS). The atomic fractions of Cu, In, Ga and Se in the CIGS films were measured by alloy reference relative sensitivity factors derived from the certified atomic fractions of a reference CIGS film. The total ion intensities of the constituent elements were obtained by a total number counting method. The atomic fractions measured by SIMS were linearly proportional to those certified by inductively coupled plasma mass spectrometry using an isotope dilution method. The uncertainties were determined from the standard uncertainties in the measurements and those of a CIGS thin film certified reference material.

Selenium fractionation and speciation in agriculture soils and accumulation in corn (Zea mays L.) under field conditions in Shaanxi Province, China

Upland and paddy soils, as well as corn samples, were collected in the selenosis area of Naore Village, Ziyang County, Shaanxi Province, China. A five-step sequential extraction procedure was used for selenium (Se) fractionation, including soluble Se, exchangeable Se and carbonate-bound Se, iron and manganese oxide-bound Se, organic matter-bound Se, and the residual Se fraction. Species of soluble Se in upland soils included Se−2, Se4+, and Se6+. The results showed that soluble Se and exchangeable Se fractions accounted for less than 1% of the total Se in the upland soil, but approximately 16.1% in the paddy soil. Concentrations of residual Se were lower than those of iron and manganese oxide-bound Se and organic matter-bound Se in both upland and paddy soils. Iron- and manganese oxide-bound Se was the dominant fractions in upland soil, whereas organic matter-bound Se abounded in paddy soil. Concentrations (mgkg−1) of Se in the corn samples ranged from 0.05 to 14.5 in seed, 0.31 to 12.3in root, 0.09 to 9.15 in stalk, and 0.16 to 36.15 in leaf. Path analysis indicated that soluble Se6+ significantly (P<0.05) affected Se accumulation in corn tissues directly, whereas the organic matter-bound Se had a significant (P<0.05) indirect effect. In conclusion, corn did not readily absorb a major portion of soil Se. However, organic matter-bound Se was an important fraction and source of plant Se in agricultural soil.

Fatty acid and phytosterol contents of some Romanian wild and cultivated berry pomaces

AbstractThe total oil content and composition of fatty acids and phytosterols of five Transylvanian (Romania) pomaces of wild and cultivated blueberries (Vaccinium myrtillus), wild cowberry (Vaccinium vitis-idaea) and raspberry (Rubus idaeus), and cultivated black chokeberry (Aronia melanocarpa), were determined by capillary gas chromatography. Out of the five pomace oils, the percentages of polyunsaturated fatty acids (PUFAs) ranged from 37 % to 69 %. The lipid classes analysed (PLs — polar lipids, TGs — triacylglycerols, SEs — sterol esters) were separated and identified using thin-layer chromatography. TGs showed the highest PUFAs content (ranging from 41.9 % to 72.5 %) and PUFAs/SFAs (saturated fatty acids) ratios (in the range of 5.8–33.1 %). In the case of PL and SE fractions, the levels of SFA were significantly higher than in TGs. The total amount of sterols was in the range of 101.6–168.2 mg per 100 g of lipids of the pomaces analysed. The predominant phytosterols were β-sitosterol, stigmastanol + isofucosterol, and campesterol. The results indicated that the investigated pomace oils, due to their good balance between n-6 and n-3 fatty acids (except for chokeberry) and high β-sitosterol content, could be excellent sources of PUFAs and phytosterols, thus suggesting potential value-added utilisation of berry waste oils for preparing functional foods or food supplements.