Classification of herbal mixtures on the basis of some metals content using pattern recognition techniques

The purpose of this study was to investigate the content of trace elements in relation to the composition of domestic herbal mixtures. Cluster analysis, principal components analysis, and self-organizing maps were applied to identify existing relationships. The concentrations of Ni, Pb, Cd, Cr, Cu, Fe, Mn, Zn in 81 samples of herbal mixtures were determined with application of FAAS. The study showed that the levels of trace elements in some herbal mixtures of the same composition were comparable. The projection of herbal samples onto topological maps of adjustable sizes allowed recognition of the identical herbal preparations characterized by dissimilar levels of trace elements. The elements which played the most important role in recognition of the herbal samples were Mn, Ni, Zn and partly Cu, Fe and Cd.     

Trace elements in aerial parts and rhizosphere of <Emphasis Type="Italic">Thymus pannonicus</Emphasis> All.

This paper brings out the results of the study on the levels of selected trace elements (Cu, Fe, Mn, Zn and Cr) in aerial parts of Thymus pannonicus All. (Lamiaceae) and rhizosphere soil from twelve locations in Serbia. Prior to assays by flame and flameless atomic absorption spectrometry, samples were subjected to microwave-assisted acid digestion. Real and potential acidity of soil samples were also measured. Obtained results for soil samples, although slightly higher for some elements (Cu: 12.38–45.18 mg/kg; Fe: 22102–46193 mg/kg; Mn: 776.95–4901.27 mg/kg; Zn: 62.27–214.02 mg/kg; Cr: 48.86–69.13 mg/kg), were found to fit into biogeochemical background. Element contents in plant samples differed depending on collecting site (Cu: 5.26–14.07 mg/kg; Fe: 25.92–1454.07 mg/kg; Mn: 89.29–278.25 mg/kg; Zn: 1.81–10.64 mg/kg; Cr: 1.11–3.51 mg/kg), which can be partly explainable by different nutrient availability influenced by soil acidity. Zinc levels in T. pannonicus were below expected and seem to be strongly influenced by plant physiological properties.     

Sequential extraction of trace metals and particle size distribution studies of Kainji Lake sediment,Nigeria

Abstract

Sequential extraction was carried out to determine the concentrations of some trace metals (Mn, Cu, Fe, Pb and Cd) in the Kainji lake sediments from seven different locations in four fractions: exchangeable, bound to iron and manganese oxide, bound to organic matters and residual. This was to undertaken to assess the environmental fate of these trace metals. The BCR technique, a modified form of the Tessier method of sequential extraction was used.

The proportion of the mean metal concentrations of the bioavailable metals follows the order Fe>Cu>Pb>Mn>Cd. Generally, Fe was most abundant metal in the sediment and about 40% was found in its bioavailable form. Although Cd contributed least to the bioavailable content, a greater percentage (~60%) was found in the bioavailable fraction. This suggests that Cd is highly mobile and, since it is known to be toxic, its concentration in the bioavailable form constitutes an environmental threat.

The contribution of metals bound to organic matter was found to be high and of the same magnitude as those bound to oxides and constitutes about 70% of the non-bioavailable metal contents. The petrological analysis of the sediments revealed that the sediments were predominantly quartz and rock clays with percussion marks and indentations.     

Effects of Excess Copper Ions on Decidualization of Human Endometrial Stromal Cells

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease, which mainly involves the joints. RA is prevalent worldwide with increasing prevalence in elderly people. The mechanism of RA pathogenesis is still undefined, and it is interplaying between genetic susceptibility and environmental factors. Although risk factors for RA are not fully established, various studies have focused on the role of trace elements in association with RA. Trace elements act as co-factors for most of the enzymes, and their deficiency is associated with many untoward effects on human health. The homeostatic alterations in the metabolism of trace elements may partly be due to inflammatory response in RA. The objective of the present study was to determine the serum concentrations and correlation of zinc, copper, and iron in RA patients and healthy controls. The study comprised of 61 RA patients and 61 age- and sex-related healthy individuals of Pakistani population. Serum levels of Zn, Cu, and Fe were measured in all the participants by atomic absorption spectrophotometer. Serum Zn and Fe were significantly reduced in the RA patients than those in the healthy controls. Serum Cu concentrations were found elevated in the RA patients. Correlation studies of trace elements determine that there was negative correlation between Zn and Cu in the RA patients and no correlation in the control group. It is very important to explore the deficiency of essential trace metals in biological samples of the RA patients in different populations which may be helpful for diagnosis and supplementary management of rheumatoid arthritis patients.     

Toxic Element Profiles in Selected Medicinal Plants Growing on Serpentines in Bulgaria

Populations of medicinal plants growing on serpentines and their respective soils were analyzed for Fe, Ni, Mn, Cr, Co, Cd, Cu, Zn, and Pb using inductively coupled plasma atomic emission spectrometry. Aqua regia extraction and 0.43 M acetic acid extraction were used for the quantification of pseudototal and bioavailable fractions, respectively, of elements in soil and nitric acid digestion for determination of total element content in plants. Screening was performed to (1) document levels of toxic metals in herbs extensively used in preparation of products and standardized extracts, (2) compare accumulation abilities of ferns and seed plants, and (3) estimate correlations between metal content in plants and their soils. The toxic element content of plants varied from site to site on a large scale. The concentrations of Fe and Ni were elevated while those of Cu, Zn, and Pb were close to average values usually found in plants. The highest concentrations for almost all elements were measured in both Teucrium species. Specific differences in metal accumulation between ferns and seed plants were not recorded. The investigated species are not hyperaccumulators but can accumulate toxic elements, in some cases exceeding permissible levels proposed by the World Health Organization and European Pharmacopoeia. The harvesting of medicinal plants from serpentines could be hazardous to humans.     

Trace elements in the teeth of Steller sea lions (<Emphasis Type="Italic">Eumetopias jubatus</Emphasis>) from the North Pacific

The occurrence of trace elements in the teeth of Steller sea lions (Eumetopias jubatus) collected from the North Pacific from 1968 to 1999 is described. Using particle-induced X-ray emission analysis, we detected eight trace elements: Ca, Mn, Fe, Cu, Zn, Br, Sr and Pb. We used a general linear model to evaluate long-term trends of trace element accumulation. Zn (Zn/Ca) and Fe (Fe/Ca) levels both varied during the last three decades, and showed significant differences between animals of different age (Fe/Ca), season (Zn/Ca and Fe/Ca), and sex (Zn/Ca); both Zn/Ca and Fe/Ca ratios were higher in young males than older males. Pb was detected in 39% of the samples from Hokkaido (Japan) and 22% of those from Alaska. The high levels of Pb recorded in 1975 were thought to be related to the use of leaded gasoline during the 1970s. Our results indicate that the levels of trace elements in the teeth of Steller sea lions can be used as indicators of temporal and spatial variations of trace element pollution.     

A high sensitivity iron-dependent bioreporter used to measure iron bioavailability in freshwaters

A Nostoc sp. PCC 7120 iron bioreporter containing iron-regulated schizokinen transporter gene alr0397 promoter fused to the luxAB genes was examined to optimize its response to bioavailable iron. Dose-response relationships between luciferase activity and free ferric ion (Fe(3+) ) concentrations pFe (-lg [Fe(3+) ]) were generated by measuring luciferase activities of the bioreporter in trace metal-buffered Fraquil medium with various incubation times. The results were best demonstrated by sigmoidal curves (pFe 18.8-21.7, Fe(3+) =?10(-18.8) -10(-21.7) M) with the linear range extending from pFe 19.6-21.5 (Fe(3+) =?10(-19.6) -10(-21.5) M) after a 12-h incubation time. Optimal conditions for the use of this bioreporter to sense the iron bioavailability were determined to be: a 12-h exposure time, initial cell density of OD(730?nm) =?0.06, high nitrate (100?μM), high phosphate (10?μM), moderate Co(2+) (0.1-22.5?nM), Zn(2+) (0.16-12?nM), Cu(2+) (0.04-50?nM), and wide range of Mn(2+) concentration (0.92-2300?nM). The applicability of using this iron bioreporter to assess iron availability in the natural environment has been tested using water samples from eutrophic Taihu, Donghu, and Chaohu lakes. It is indicated that the bioreporter is a useful tool to assess bioavailable iron in various water quality samples, especially in eutrophic lakes with high bioavailable iron.     

Use of granules and free salts for Fe and Zn fortification of leafy vegetables: Improvements in trace element bioaccessibility and fulfillment of Dietary Reference Intakes

BackgroundLeafy vegetables represent an excellent dietary source of trace elements such as Fe and Zn. Nevertheless, Fe and Zn bioaccessibility can lessen due to a high concentration of anti-nutritional compounds. The encapsulation of Fe and Zn salts as granules could be used to fortify these leafy vegetables.MethodThree leafy vegetables, spinach, Swiss chard and Ethiopian mustard were fortified with iron sulfate and zinc sulfate as granules and free salts in order to test the improvements in the bioaccessibility and fulfillments of DRIs. Fe and Zn granules were prepared in a fluidized bed granulator. A probabilistic analysis was performed, using experimental data, to assess bioaccessible intake and fulfillments of DRIs in European populations.ResultsFe contents ranged between 4.8 mg/100 g of Ethiopian mustard to 157.4 mg/100 g of spinach. Fe and Zn bioaccessibility percentages were low for Swiss chard and spinach without fortification. Fortification with granules improved Fe bioaccessibility of these latter vegetables (196 and 223 mg/100 g). Zn contents in samples without fortification ranged between 2.3 mg/100 g for Ethiopian mustard and 7.4 mg/100 g for spinach. Zn fortification as granules improved Zn bioaccessibility for the three vegetables studied. Thus, Zn bioccessible concentrations ranged between 17.4 and 108 mg/100 g for the solubility assay and between 5.9 and 31.1 mg/100 g for the dialyzability assay. Besides, the probability analysis showed that fortification had a better performance in meeting DRIs for those populations with higher consumption levels of leafy vegetables.ConclusionsThe probability analysis demonstrated that fortification can be a suitable strategy to meet DRIs for both trace elements, which was especially remarkable for Fe. Fortification with granule was more effective in most the cases, although for Ethiopian mustard, free salt of Fe showed a better performance.     

Estimation of Trace Elements in Mace (Myristica fragrans Houtt) and Their Effect on Uterine Cervix Cancer Induced by Methylcholanthrene

In the present work, trace elemental analysis of mace (Myristica fragrans Houtt) was carried out by the atomic absorption spectrometry technique. The concentrations of various elements analyzed in this medicine were ranked in decreasing order: selenium (Se)?>?zinc (Zn)?>?magnesium (Mg)?>?iron (Fe)?>?calcium (Ca)?>?manganese (Mn)?>?lead (Pb). The concentrations of Mg, Zn, Fe, Mn, Ca, and Se were significantly decreased in serum of methylcholanthrene tumor models (P?<?0.001) compared with the control and mace groups. It is consistent with the result of tumor incidence. These trace elements could be directly or indirectly responsible for the antitumor activity of mace. The inorganic elements in this folk remedy can partly account for the antitumor.     

Sulfate reduction in coastal ecosystems

The diversity and activity of dissimilatory Fe(III)-reducing bacteria was investigated in acidic, ochre-precipitating springs on Mam Tor, East Midlands, UK. The springs at this acid rock drainage site are located below a 3000 year old landslip, where biooxidation of exposed pyrite-containing minerals has resulted in the production of metal-laden acidic waters. A diverse microbial community was found downstream in the sediments dominated by Fe(III) minerals, and included close relatives to known acidophilic (Acidimicrobium and Acidiphilium) and neutraphilic (Geobacter and Pelobacter) Fe(III)-reducing bacteria. Analysis by XRD and TEM confirmed the presence of both amorphous and well-defined Fe(III) mineral phases in the sediments including lepidocrocite, goethite and schwertmannite. Microcosm-based experiments demonstrated that the bioavailable Fe(III) was reduced under anaerobic conditions, concomitant with sulphate release. XRD analysis suggested that schwertmannite (an iron sulphate hydroxide) was utilized preferentially by the Fe(III)-reducing bacteria, leading to the release of sulphate. Although the microcosms contained sufficient concentrations of naturally occurring electron donor to sustain significant levels of Fe(III) reduction, this process was stimulated by the addition of glycerol and complex electron donors. Thus, the acidic Fe(III)-containing sediments contain a diversity of DIRBs that can be stimulated by the addition of electron donor as a first step in the reversal of acid rock and acid mine drainage contamination.     

Acid-Generating and Leaching Potential of Soils in a Coal Waste Rock Pile in Northeastern China

The present study involved the assessment of potential generation of acid drainage and also metal leaching from an abandoned large (175 m) low sulfur waste rock pile—the dominant mine waste at the site—at the Haizhou coal mine. Laboratory-based static and column leaching tests on waste rock samples were conducted. The static tests were done for 8 composite samples collected from different parts of pile. A column study was performed using mixture of waste rock soil samples to assess metals attenuation process of background soils in vicinity of pile when rainwater reacts with low-sulfide waste rocks. Total concentration of major elements in solid samples was determined using dispersive X-ray fluorescence spectrometry (XRF) and chemical analysis of leachate were measured by inductively coupled plasma optical emission spectrometry (ICP-OES), ion chromatography and titration methods. The inverse geochemical modeling using PHREEQC was applied to explain possible mass transfer processes between column leachates of waste pile and background soils. Static tests (including acid–base accounting (ABA) and net acid generation (NAG)) and mineralogical information suggest that the waste rock is non-acid generating. The large amount of aluminosilicate minerals and probably trace amounts of carbonates with respect to low sulfur content of waste rock pile represents a potentially large source of neutralization potential according to static test results. It was also found that presence of inherent neutralizing materials in waste rock and also in surrounding background soils provide sufficient neutrality and possibly immobilize the trace and heavy metal contents of waste rocks and potentially protects water resources.     

Trace elements in the human central nervous system studied with neutron activation analysis

The central nervous system (CNS) should be especially sensitive to disturbances in trace element concentrations because of its high metabolic rate and low capacity for regeneration. Comparatively few studies have been made on trace elements in the CNS, which prompted us to begin a study of trace elements in four different brain lobes of the CNS, as well as in the spinal cord. Samples were obtained at autopsy and handled carefully in order to avoid contamination. They were freeze-dried and sealed in quartz tubes that were irradiated in a nuclear reactor. A simple chemical separation into six fractions was performed. The gamma spectra for these fractions was registered using a Ge(Li) detector and a computerized multichannel analyzer. Results for the following elements were obtained: Ca, Cd, Co, Cr, Cs, Cu, Fe, Rb, Se, and Zn, as well as for Na and K (not reported). Other elements were also detected in some samples. Using this technique, brain samples from ten patients with Alzheimer’s disease and ten control cases were examined.     

Trace element contamination in feather and tissue samples from Anna’s hummingbirds

Trace element contamination (17 elements; Be, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Mo, Cd, Ba, Hg, Tl, and Pb) of live (feather samples only) and deceased (feather and tissue samples) Anna's hummingbirds (Calypte anna) was evaluated. Samples were analyzed using inductively coupled plasma-mass spectrometry (ICP-MS; 17 elements) and atomic absorption spectrophotometry (Hg only). Mean plus one standard deviation (SD) was considered the benchmark, and concentrations above the mean + 1 SD were considered elevated above normal. Contour feathers were sampled from live birds of varying age, sex, and California locations. In order to reduce thermal impacts, minimal feathers were taken from live birds, therefore a novel method was developed for preparation of low mass feather samples for ICP-MS analysis. The study found that the novel feather preparation method enabled small mass feather samples to be analyzed for trace elements using ICP-MS. For feather samples from live birds, all trace elements, with the exception of beryllium, had concentrations above the mean + 1 SD. Important risk factors for elevated trace element concentrations in feathers of live birds were age for iron, zinc, and arsenic, and location for iron, manganese, zinc, and selenium. For samples from deceased birds, ICP-MS results from body and tail feathers were correlated for Fe, Zn, and Pb, and feather concentrations were correlated with renal (Fe, Zn, Pb) or hepatic (Hg) tissue concentrations. Results for AA spectrophotometry analyzed samples from deceased birds further supported the ICP-MS findings where a strong correlation between mercury concentrations in feather and tissue (pectoral muscle) samples was found. These study results support that sampling feathers from live free-ranging hummingbirds might be a useful, non-lethal sampling method for evaluating trace element exposure and provides a sampling alternative since their small body size limits traditional sampling of blood and tissues. The results from this study provide a benchmark for the distribution of trace element concentrations in feather and tissue samples from hummingbirds and suggests a reference mark for exceeding normal. Lastly, pollinating avian species are minimally represented in the literature as bioindicators for environmental trace element contamination. Given that trace elements can move through food chains by a variety of routes, our study indicates that hummingbirds are possible bioindicators of environmental trace element contamination.     

Chemical composition and theoretical nutritional evaluation of the produced fractions from enzymic hydrolysis of salmon frames with Protamex™

An amount of 200 kg fresh salmon frames were enzymic hydrolysed with the commercial protease mixture Protamex™, which is known to produce non-bitter hydrolysates. After the enzymic procedure the frames were separated by centrifugation into five fractions: an aqueous fraction rich in peptides, an insoluble fraction, an emulsion fraction, salmon oil and a bone fraction. Approximately 48% of total crude protein present in the salmon frames were found in the aqueous fraction, in which the lipid content was reduced to <0.1% in dry samples after ultramembrane filtration (UF fraction). The UF fraction was low in tryptophan, leucine and phenylalanine+tyrosine, but high in taurine. Nearly 19% of total crude protein present in the salmon frames were found in the insoluble fraction. This fraction was high in most of the indispensable amino acids. Approximately 77% of total lipids present in the salmon frames were isolated as salmon oil, which was high in both eicosapentaenic acid (EPA) and docosahexaenic acid (DHA). The bone fraction contained 62% of total ash present in the salmon frames and was high in the minerals Ca, P and Mg and also in the trace elements Cu, Fe, I, Mn, Se and Zn. All of the produced fractions were low in the undesirable substances As, Cd, Hg and Pb. For future studies the UF fraction and salmon oil might be interesting as health promoting agents, the insoluble fraction as dietary protein supplement and the bone fraction as dietary mineral supplement.     

Accumulation of trace elements in agricultural topsoil under different geological background

For establishing rational farming mechanism, it is essential to know the relative contribution of different geological background and anthropogenic activities to trace elements in agricultural soil. In this paper, 282 surface soil samples were collected based on the different geological background. Five harmful trace elements (As, Cd, Cr, Hg and Pb) were analyzed. The results indicated most of trace elements contents were far beyond the threshold of uncultivated soil background, which indicate anthropogenic input strongly influenced on trace elements in agricultural soil. In addition, correlation analysis showed trace element contents exhibited high relationships with soil pH, C/N and physical clay (<0.01 mm) (p?<?0.05). The principal component analysis showed that the first component included Cd, Cr and Hg, while Pb and As formed the second component. Furthermore, in the agricultural topsoil derived from carbonate rock, the high background values of trace elements and alkaline condition made the enrichments of Cd, Cr and Hg were the most significant. In the agricultural topsoil derived from red residua, the Pb and As contents was the highest values among the soil categories, partly because the type of soil had amount of physical clay (<0.01 mm). In the agricultural topsoil derived from shale, the pH or physical clay had significant relationship with Cd, Pb, Hg and As (p?<?0.01). In the agricultural topsoil derived from sand stone, the acid condition and loose texture might account for the lowest values of Cd, Cr, Pb and As content to some extent.     

Effects of nitrogen and water addition on trace element stoichiometry in five grassland species

A 9-year manipulative experiment with nitrogen (N) and water addition, simulating increasing N deposition and changing precipitation regime, was conducted to investigate the bioavailability of trace elements, iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn) in soil, and their uptake by plants under the two environmental change factors in a semi-arid grassland of Inner Mongolia. We measured concentrations of trace elements in soil and in foliage of five common herbaceous species including 3 forbs and 2 grasses. In addition, bioaccumulation factors (BAF, the ratio of the chemical concentration in the organism and the chemical concentration in the growth substrate) and foliar Fe:Mn ratio in each plant was calculated. Our results showed that soil available Fe, Mn and Cu concentrations increased under N addition and were negatively correlated with both soil pH and cation exchange capacity. Water addition partly counteracted the positive effects of N addition on available trace element concentrations in the soil. Foliar Mn, Cu and Zn concentrations increased but Fe concentration decreased with N addition, resulting in foliar elemental imbalances among Fe and other selected trace elements. Water addition alleviated the effect of N addition. Forbs are more likely to suffer from Mn toxicity and Fe deficiency than grass species, indicating more sensitivity to changing elemental bioavailability in soil. Our results suggested that soil acidification due to N deposition may accelerate trace element cycling and lead to elemental imbalance in soil–plant systems of semi-arid grasslands and these impacts of N deposition on semi-arid grasslands were affected by water addition. These findings indicate an important role for soil trace elements in maintaining ecosystem functions associated with atmospheric N deposition and changing precipitation regimes in the future.     

Bioavailability of phosphorus in agriculturally loaded rivers in southern Finland

The potential bioavailability of phosphorus in agriculturally loaded rivers of southern Finland was determined by an algal bioassay and the release of the potentially bioavailable particulate P was estimated by sorption studies. According to the bioassay 0 to 13.2 per cent (mean 5.1%) of the particulate P in river water samples was potentially bioavailable. Dissolved reactive P (DRP) in river waters appeared to be totally bioavailable whereas the dissolved unreactive P appeared not to be utilized by algae. In addition to river waters two lake sediment samples were also assayed. In these samples 0 and 2.6% of the P was bioavailable. The potential bioavailability of particulate P in agriculturally loaded rivers obtained in this study was lower than that reported in studies from other countries. The difference was assumed to arise partly from methodological factors and partly from the nature of the Finnish soils. The EPC (equilibrium phosphate concentration) values indicated that during the period when most of the agricultural loading enters the lakes in Finland, potentially bioavailable P is not released from the particles because of the relatively high DRP concentration in the receiving waters. However, during the algal production period the DRP concentration in lakes decreases below the EPC and potentially bioavailable particulate P is desorbed. The increase in pH during this period may further enhance the desorption of P.     

Mineral- and trace element concentrations in human breast milk,placenta, maternal blood,and the blood of the newborn

The concentrations of the essential trace elements Cu, Fe, and Zn, and of the mineral elements Ca, K, Mg, and P during the perinatal period in human placenta and in the blood of the mother and the newborn (cord blood) were determined. Breast milk (colostrum and transitory milk) was also included to permit correlations between the different compartments. No correlations were found. The uptake by nutrition and the body-pools of the mother and their mobilization for these elements seem to be sufficiently high for an adequate supply of the fetus and the milk in the geographical region of Munich (Bavaria, FRG) under these investigations. Differences in the mineral- and trace element concentrations of colostrum and transitory milk for the elements P and Zn and to a lesser extent for Ca and Mg were observed. Additionally, breast milk samples from different geographical regions in Bavaria were investigated. Results for the heavy metals Cd, Hg, and Pb, and for the essential trace element Se are also presented for these samples, and can be seen as a reflection of the overall environmental and dietary influences during pregnancy in these geographical regions. ICP (Inductively Coupled Plasma)-emission spectrometry was used for the determination of the elements Cu, Fe, Zn, Ca, K, Mg, and P. For the additionally given elements in the milk-samples anodic stripping voltammetry (DPASV) (Cd, Pb), hydride atomic absorption spectrometry (AAS) (Se), and cold vapor AAS (Hg) were applied.     

Evaluation of trace element status of organic dairy cattle

The present study aimed to evaluate trace mineral status of organic dairy herds in northern Spain and the sources of minerals in different types of feed. Blood samples from organic and conventional dairy cattle and feed samples from the respective farms were analysed by inductively coupled plasma mass spectrometry to determine the concentrations of the essential trace elements (cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), iodine (I), manganese (Mn), molybdenum (Mo), nickel (Ni), selenium (Se) and zinc (Zn)) and toxic trace elements (arsenic (As), cadmium (Cd), mercury (Hg) and lead (Pb)). Overall, no differences between organic and conventional farms were detected in serum concentrations of essential and toxic trace elements (except for higher concentrations of Cd on the organic farms), although a high level of inter-farm variation was detected in the organic systems, indicating that organic production greatly depends on the specific local conditions. The dietary concentrations of the essential trace elements I, Cu, Se and Zn were significantly higher in the conventional than in the organic systems, which can be attributed to the high concentration of these minerals in the concentrate feed. No differences in the concentrations of trace minerals were found in the other types of feed. Multivariate chemometric analysis was conducted to determine the contribution of different feed sources to the trace element status of the cattle. Concentrate samples were mainly associated with Co, Cu, I, Se and Zn (i.e. with the elements supplemented in this type of feed). However, pasture and grass silage were associated with soil-derived elements (As, Cr, Fe and Pb) which cattle may thus ingest during grazing.     

海南野生石斛中必需微量元素与必需氨基酸的分析

本文对几种海南野生石斛(红头金石斛、重唇石斛、流苏金石斛、华石斛、密花石斛、刀叶石斛)及人工栽培的金钗石斛,进行了人体及植物必需微量元素和人体必需氨基酸的含量分析.结果表明:每种石斛中均含有植物和人体所需的7种微量元素和7种人体必需氨基酸,其中流苏金石斛的微量元素和氨基酸含量均高于其他种.人工栽培的金钗石斛其微量元素和氨基酸含量与海南野生石斛比较,差异不大,仅在Fe、Mn两个元素均低于野生种.本文还进行了植物必需微量元素与必需氨基酸相关性的讨论.