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1.
Mikulewicz M Chojnacka K Woźniak B Downarowicz P 《Biological trace element research》2012,146(2):272-280
In this paper, we report the results of an in vitro experiment on the release of metal ions from orthodontic appliances composed
of alloys containing iron, chromium, nickel, silicon, and molybdenum into artificial saliva. The concentrations of magnesium,
aluminum, silicon, phosphorus, sulfur, potassium, calcium, titanium, vanadium, manganese, iron, cobalt, copper, zinc, nickel,
and chromium were significantly higher in artificial saliva in which metal brackets, bands, and wires used in orthodontics
were incubated. In relation to the maximum acceptable concentrations of metal ions in drinking water and to recommended daily
doses, two elements of concern were nickel (573 vs. 15 μg/l in the controls) and chromium (101 vs. 8 μg/l in the controls).
Three ion release coefficients were defined: α, a dimensionless multiplication factor; β, the difference in concentrations (in micrograms per liter); and γ, the ion release coefficient (in percent). The elevated levels of metals in saliva are thought to occur by corrosion of the
chemical elements in the alloys or welding materials. The concentrations of some groups of dissolved elements appear to be
interrelated. 相似文献
2.
Pseudomonas sp. NBRI 4014 is a potent phosphorus solubilizer (284 μg/ml). It also produced significant levels of siderophore (143.87
μg/ml) and IAA (5.6 μg/ml). Siderotyping indicated it was P. aeruginosa siderovar 1. Cadmium (180 μM), nickel (420 μM), and chromium (370 μM) resistant mutants were developed and characterized
for their PGPR properties. Mutants were stable under non-selective pressure. In cases of nickel and cadmium, there were reductions
of the siderophore levels. However, they were able to promote root and shoot elongation in soybeans (Glycine max PK 564) at a significant level (p < 0.05) in the presence of metals unfamiliar to the wild type. The persistence and stability of mutants were evident in rhizospheric
soil, thus their exploitation for polluted/contaminated sites was supported.
Received: 27 December 2001 / Accepted: 28 January 2002 相似文献
3.
Tascilar ME Ozgen IT Abaci A Serdar M Aykut O 《Biological trace element research》2011,143(1):188-195
The quality of the diet of obese children is poor. Eating habits may alter micronutrient status in obese patients. In this
study, we determined the serum levels of selenium, zinc, vanadium, molybdenum, iron, copper, beryllium, boron, chromium, manganese,
cobalt, silver, barium, aluminum, nickel, cadmium, mercury, and lead in obese Turkish children. Thirty-four obese and 33 healthy
control subjects were enrolled in the study. Serum vanadium and cobalt levels of obese children were significantly lower than
those of the control group (0.244 ± 0.0179 vs. 0.261 ± 0.012 μg/l, p < 0.001, and 0.14 ± 0.13 vs. 0.24 ± 0.15 μg/l, p = 0.011, respectively). There was no significant difference between groups regarding the other serum trace element levels.
In conclusion, there may be alterations in the serum levels of trace elements in obese children and these alterations may
have a role in the pathogenesis of obesity. 相似文献
4.
Beob G. Kim Julye M. Adams Brian A. Jackson Merlin D. Lindemann 《Biological trace element research》2010,133(2):171-180
Dietary chromium(III) picolinate (CrPic) effects on circulating steroid hormones have been reported in various experimental
animals. However, direct effects of CrPic on adrenocortical steroidogenesis are uncertain. Therefore, the objective was to
determine the effects of CrPic on cortisol and dehydroepiandrosterone sulfate (DHEAs) secretion from H295R cells. In experiment
1, a 24-h exposure to CrPic (0 to 200 μM) had both linear (p < 0.001) and quadratic (p < 0.001) effects on cortisol secretion from forskolin-stimulated cells with the highest cortisol secretion at 0.1 μM of CrPic
and the lowest at 200 μM of CrPic. In experiment 2, a 48-h exposure to CrPic (200 μM) decreased cortisol (p < 0.07) release from forskolin-stimulated cells during a 24-h collection period. In experiment 3, a 48-h exposure to CrPic
(100 μM) decreased cortisol (p < 0.05) and DHEAs (p < 0.01) from forskolin-stimulated cells during a 24-h sampling period. In experiment 4, a 24-h exposure to forskolin followed
by a 24-h exposure to both forskolin and CrPic (100 and 200 μM) decreased both cortisol and DHEAs secretion (p < 0.01). This study suggests that at high concentrations, CrPic inhibits aspects of steroidogenesis in agonist-stimulated
adrenocortical cells. 相似文献
5.
The concentrations of arsenic (As), beryllium (Be), cadmium (cd), chromium (Cr), mercury (Hg), manganese (Mn), nickel (Ni),
lead (Pb), tin (Sn), thallium (Tl), and vanadium (V) were determined in a number of food items purchased in zones of Tarragona,
County (Catalonia, Spain) near a hazardous waste incinerator (HWI), which has been operating since 1999. Food samples corresponded
to the following groups: meat, fish and seafood, pulses, cereals, vegetables, fruits, tubers, whole milk, yogurt, eggs, and
sugar. Be and Tl were under their respective limits of detection in all samples. For the analyzed trace elements, the dietary
intake by the general population of Tarragona was 458.5 μg/d for As, 14.3 μg/d for Cd, 88.3 μg/d for Cr, 5.3 μg/d for Hg,
2421.4 μg/d for Mn, 138.3 μg/d for Ni, 44.8 μg/d for Pb, 34.6 μg/d for Sn, and 28.9 μg/d for V. Results were compared with
those found in a baseline survey carried out in the same area during the construction of the HWI (1996–1998). In general terms,
the dietary intake of metals in 2003 was comparatively similar to those found in the baseline survey. For the most toxic elements
(As, Cd, Hg, and Pb), it was under their respective Provisional Tolerable Weekly Intake (PTWI) estabished by the FAO/WHO. 相似文献
6.
Somatic embryogenesis and whole plant regeneration was achieved in callus cultures derived from immature zygotic embryos of
Prosopis laevigata (Humb. & Bonpl. ex Willd.) M.C. Johnst., recently identified as chromium (Cr), cadmium (Cd), lead (Pb) and nickel (Ni) accumulator. Embryogenic calli were induced on Murashige and Skoog (MS) medium added with a mixture of organic components plus N-6 benzyladenine
(BA) (6.62 μM) and 2,4-dichlorophenoxyacetic acid (2,4-D) (2.26 μM) or thidiazuron (4.54–9.08 μM) and indole-3-acetic acid
(1.42 μM). Embryogenic calli transferred onto half-strength MS medium without plant growth regulators developed globular
embryos, of which 20% matured when treated with 3.75% (w/v) polyethylene glycol (PEG), and of these 50% fully differentiated into plantlet embryo. Regenerated plants were successfully
acclimatized (90%), while in vitro seedlings transferred to MS medium containing 0.5 mM Cd, Cr, Ni or Pb, exhibited high heavy
metals accumulation (627 mg Cr kg−1, 5,688 mg Cd kg−1, 1,148 mg Ni kg−1, and 3,037 mg Pb kg−1 dry weight) and efficient roots to shoots translocation (42–73%). 相似文献
7.
Suleyman Patlar Ekrem Boyali Abdulkerim Kasim Baltaci Rasim Mogulkoc 《Biological trace element research》2011,139(3):296-300
The present study aims to examine the effects of both physical activity and vitamin A supplementation on trace element metabolism
in individuals engaged in taekwondo. The study registered seven healthy male national taekwondo players whose mean age was
21.86 ± 0.34 years and mean weight was 64.86 ± 2.72 kg. The subjects were supplemented with oral administration of 100 mg
vitamin A (retinol) for 6 weeks, and concurrently, they were subjected to taekwondo training 5 days a week. Before starting
the vitamin A supplementation, blood samples were taken from the subjects twice, once at rest and once after exhaustion. Similarly,
at the end of the 6-week vitamin A supplementation, two blood samples were taken from the subjects, once at rest and once
after exhaustion, in order to determine (by atomic emission) and compare serum cobalt, molybdenum, calcium, cadmium, chromium,
copper, manganese, sodium, nickel, phosphorus, sulfur, iron, boron, and zinc (mg/L) levels. Values of boron and nickel dropped
significantly after 6-week vitamin A supplementation (p < 0.001). Reduced levels of boron and nickel we obtained in the present study are believed to result from the antioxidant
effect of long-term vitamin A supplementation. 相似文献
8.
This study considers the cycling of nitrogen in the waters of the North Sea, particularly focussing on organic nitrogen. Dissolved
inorganic nitrogen (DIN), dissolved organic nitrogen (DON) and particulate organic nitrogen (PON) were measured in the North
Sea over a one-year period (autumn 2004–summer 2005). The surface water concentrations of nitrate, ammonium, DON and PON during
the present study ranged from <0.1–7.2 μM, <0.1–2.0 μM, 1.9–11.2 μM and 0.3–5.6 μM, respectively, with DON the dominant fraction
of total nitrogen at all times. These nutrients concentrations were significantly lower compared to previous studies in the
southern North Sea. The seasonal variations showed high mean surface concentrations of nitrate (4.7 ± 0.6 μM) and DON (8.9 ± 0.9 μM),
low ammonium (<0.1 μM) and PON (0.8 ± 0.1 μM) in winter, shifting to low nitrate (0.3 ± 0.3 μM) and DON (4.2 ± 1.2 μM) in
summer, with high ammonium (0.8 ± 0.4 μM) in autumn and PON (2.5 ± 1.2 μM) in spring. Highest mean surface DON concentration
was measured in winter and may be due to resuspension of the organic matter from the bottom sediments. For autumn and spring,
phytoplankton DON release was likely to be the most significant source of DON as shown by high concentrations of low molecular
weight (LMW) DON and its positive correlation to chlorophyll a. Low total and LMW DON concentrations during summer were likely to be due to the uptake of the LMW DON fraction by phytoplankton
and bacteria and the stratification of the water column. DON is therefore shown to be a potentially important source of nitrogen
in shelf seas especially after the spring bloom has depleted nitrate to limiting concentrations.
Handling editor: L. Naselli-Flores 相似文献
9.
Forrest H. Nielsen Terrence R. Shuler Thomas J. Zimmerman Michael E. Collings Eric O. Uthus 《Biological trace element research》1979,1(4):325-335
The interaction between nickel and iron was confirmed in rat metabolism. In a fully-crossed, two-way, three by four, factorially
designed experiment, female weanling rats were fed a basal diet supplemented with iron at 0, 25, 50, and 100 μg/g and with
nickel at 0, 5, and 50 μg/g. The basal diet contained about 10 ng of nickel and 2.3 μg of iron/g. After nine weeks, dietary
iron affected growth, hematocrit, hemoglobin, plasma cholesterol, and in liver affected total lipids, phospholipids, and the
contents of copper, iron, manganese, and zinc. By manipulating the iron content of the diet, effects of dietary nickel were
shown in rats that were not from dams fed a nickel-deprived diet. Nickel affected growth, hematocrit, hemoglobin, plasma alkaline
phosphatase activity, plasma total lipids, and in liver affected total lipids, and the contents of copper, manganese, and
nickel. The interaction between nickel and iron affected hematocrit, hemoglobin, plasma alkaline phosphatase activity, and
plasma phospholipids, and in liver affected size, content of copper, and perhaps of manganese and nickel. In severely iron-deficient
rats, the high level of dietary nickel partially alleviated the drastic depression of hematocrit and hemoglobin, and the elevation
of copper in liver. Simultaneously, high dietary nickel did not increase the iron level in liver and was detrimental to growth
and appearance of severely iron-deficient rats. In nickel-deprived rats fed the borderline iron-deficient diet (25 μg/g) hematocrit
and hemoglobin also were depressed. However, 5 μg Ni/g of diet were just as effective as 50 μg Ni/g of diet in preventing
those signs of nickel deprivation. The findings in the present study suggested that nickel and iron interact with each other
at more than one locus. 相似文献
10.
Esther Fernández-Miñano Clara Ortiz Ascensión Vicente José L. Calvo Antonio J. Ortiz 《Biometals》2011,24(5):935-941
Although the metal devices used in orthodontic treatments are manufactured highly resistance to corrosion, they may still
suffer some localized corrosion resulting from the oral cavity conditions. The corrosion causes the release of metals from
the alloys used for their manufacture. In this report, we evaluated the in vivo metal ions release of three alloys (stainless
steel, titanium and nickel-free) usually used in the orthodontics treatments and its genotoxicity. We applied to 15 patients,
between 12 and 16 years, 4 tubes and 20 brackets. Samples from oral mucosa were taken before the treatment and 30 days later.
The concentration of the titanium, chromium, manganese, cobalt, nickel, molybdenum and iron were detected using inductively
coupled plasma mass spectrometry (ICP-MS). The genotoxicity was measured with a comet assay (Olive moment). The oral mucosa
cells in contact with the stainless steel alloy displayed the greatest titanium and manganese concentrations and those in
contact with the nickel-free alloy presented the greatest concentration of chromium and iron. Both alloys, stainless steel
and nickel-free, induced a higher DNA damage in the oral mucosa cells than the titanium alloy, in which the Olive moment was
similar to controls. Based on the results of our study, we can conclude that titanium brackets and tubes are the most biocompatible
of the three alloys. 相似文献
11.
Ghazi Sh Habibian M Moeini MM Abdolmohammadi AR 《Biological trace element research》2012,146(3):309-317
This experiment was carried out to investigate the effects of different levels of organic and inorganic chromium on the performance,
immune function and some serum mineral concentrations of broilers under heat stress condition (23.9–37°C cycling). A total
of 150 one-day-old broiler chicks according to a completely randomized design were assigned into five treatment groups. Each
treatment consisted of three replicates and each replicate contained ten chicks. Chicks were fed on corn–soybean meal basal
diets with added different concentrations of chromium (0, 600 and 1,200 μg kg−1 chromium chloride or 600 and 1,200 μg/kg chromium l-methionine) from 1 to 49 days of age. Humoral immunity was assessed by intravenous injection of 7% sheep red blood cell (SRBC)
followed by evaluation of serum for antibody titers in primary and secondary responses. Cell-mediated immunity was assessed
by the cutaneous basophil hypersensitivity (CBH) test to phytohemagglutinin (PHA)-P at day 32 and PHA-M at day 48. Heterophil/lymphocyte
(H/L) ratio was also measured as a reliable indicator of stress. The body mass, feed intake and conversion ratio were not
influenced by dietary chromium (P > 0.05). Dietary supplementation of both organic and inorganic chromium significantly increased primary and secondary antibody
responses (P < 0.01), and also improved H/L ratio (P < 0.05), CBH response (P < 0.01) as well as relative weights of thymus (P < 0.05) and spleen (P < 0.01). Both dietary organic and inorganic chromium caused an increase in serum concentrations of Cr and Zn (P < 0.01), but decreased the serum concentration of Cu (P < 0.01). These results suggest that supplemental chromium especially in organic form offers a good management practice to reduce
heat stress-related depression in immunocompetence of broiler chicks. 相似文献
12.
Levels of nine heavy metals were measured in the livers and salt glands of greater scaup (Aythya marila), black duck (Anas rubripes) and mallard (A. platyrhynchos) from Raritan Bay, New Jersey to determine if the functioning avian salt gland concentrates heavy metals. Heavy metals examined were cadmium, cobalt, chromium, copper, lead, mercury, manganese, nickel and zinc. Heavy metal levels varied significantly by species and tissue for chromium, copper, lead, and manganese, and by tissue for cobalt, mercury, nickel and zinc. In comparing tissues cobalt was higher in the salt glands than in livers of all three species; chromium and nickel were higher in the salt gland than liver for mallard and black duck; and lead, manganese and zinc were higher in the liver than the salt gland in greater scaup. Generally metal levels were higher in the salt gland for mallard and black duck, and in the liver for greater scaup. 相似文献
13.
The distribution of summer phytoplankton across the Straits of Magellan (SOM) was studied with the aims of tracing differences
among the distinct subregions of the area and contributing to the knowledge of its biodiversity. Samples collected at 25 stations
were observed and counted in light microscopy. Selected samples were observed with transmission electron microscopy. The main
unifying feature of the phytoplankton in the SOM was the high abundance and numerical dominance of small-sized (<10 μm) eukaryotic
species, among which coccoid cells of <3 μm size were predominant (56.2 ± 30.6 of the total phytoplankton abundance). They
mostly belonged to the prasinophyte Pycnococcus provasolii, which was abundant (0.8–6,834 cells × 103 ml−1) at all stations with the exception of those in proximity to the Atlantic entrances, where it was not recorded. Small-sized
(<3 and 3–5 μm) diatoms (Minidiscus trioculatus, Lennoxia faveolata and other undetermined centric species) attained high densities (<3,757 cells 103 ml−1) especially at stations of the Patagonian sectors, whereas microplanktonic diatoms were only found at the two entrances of
the Straits. Dinoflagellates were constituted mainly by >10 μm forms in the Andean subregion and <10 μm naked species in the
Patagonian subregion, contributing up to 75.9 and 41.8% of the total carbon in these two areas, respectively. In the Patagonian
subregion, flagellates mainly constituted by <5 μm forms and by cryptomonads <10 μm comprised up to 53.9% of the total biomass.
Several species identified in this study have never been reported in other investigations in the SOM, while others, including
Pycnococcus provasolii and Lennoxia faveolata, have rarely been recorded elsewhere. Overall, the summer phytoplankton of the Straits does not resemble that of any other
region of the world’s seas. Although some of the predominant species might have been overlooked elsewhere, their abundance
and relative importance apparently constitute a distinctive feature of the SOM. 相似文献
14.
This study is a part of a monitoring program for the determination of metals in various human tissues of the population living
in the vicinity of a new hazardous waste incinerator (HWI) in Constantí (Tarragona County, Spain). Concentrations of arsenic
(As), beryllium (Be), cadmium (Cd), chromium (Cr), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb), tin (Sn), thallium
(Tl), and vanadium (V) were determined in brain, bone, kidney, liver, and lung autopsy samples collected in 2003 from 22 individuals
who had been living for at least 10 yr in the area under evaluation. Results were compared with the metal levels obtained
in a baseline study, which was performed during the construction of the HWI (1996–1998). In the present survey, As, Be, Tl,
and V levels were not detected in any of the analyzed tissues, while Cr concentrations were very close to the limit of detection.
The highest levels of Cd and Hg were found in kidney (17.46 μg/g and 0.23 μg/g, respectively), those of Mn in liver (1.07
μg/g), and those of Ni, Pb, and Sn in bone (1.16 μg/g, 2.11 μg/g, and 0.34 μg/g, respectively). In comparison to the results
of the baseline study, a general reduction of most metal concentrations was observed in the current survey. 相似文献
15.
Summary Heavy metals including mercury, cadmium, cobalt, and copper (100 μM) exerted an adverse effect on the viability of isolated rat adrenal capsular (zona glomerulosa), adrenal decapsular (fasciculata
and reticularis), and Leydig cells of the testis with mercury being the most potent. Due to the decreased cell viability there
was a parallel reduction in corticotropin-stimulated, corticosterone production by adrenal decapsular cells and luteinizing
hormone-stimulated testosterone production by Leydig cells. The results indicated a direct toxic action of these heavy metals
on steroid-producing cell in the adrenal gland and the tectis. Other metals tested, including lead, zinc, aluminum, chromium,
iron, nickel, and lithium, did not exert any deleterious effect on cell viability or hormone-induced steroidogenesis, in adrenal
and Leydig cells when tested up to a concentration of 100 μM. 相似文献
16.
Golam Kibria Monzurul Amin Roni Mohammad Shahriarul Absar Reza-ul Jalil 《AAPS PharmSciTech》2008,9(4):1240-1246
The present study was designed to investigate the effect of two plasticizers, i.e., triethyl citrate (TEC) and polyethylene
glycol 6000 (PEG 6000) on the in vitro release kinetics of diclofenac sodium from sustained-release pellets. Ammonio methacrylate copolymer type B (Eudragit RS
30 D) is used as the release-retarding polymer. Both plasticizers were used at 10% and 15% (w/w) of Eudragit RS 30 D. Pellets were prepared by powder layering technology and coated with Eudragit RS 30 D by air suspension
technique. Thermal properties of drug and drug-loaded beads were studied using differential scanning calorimeter (DSC). DSC
thermogram represented the identity of raw materials and exhibited no interaction or complexation between the active and excipients
used in the pelletization process. Dissolution study was performed by using USP apparatus 1. No significant difference was
observed among the physical properties of the coated pellets of different batches. When dissolution was performed as pure
drug, about 8.22% and 90% drug was dissolved at 2 h in 0.1 N HCl and at 30 min in buffer (pH 6.8), respectively. From all
formulations, the release of drug in acid media was very negligible (maximum 1.8 ± 0.08% at 2 h) but in buffer only 12% and
30% drug was released at 10 h from coated pellets containing TEC and PEG 6000, respectively, indicating that Eudragit RS 30
D significantly retards the drug release rate and that drug release was varied according to the type and amount of plasticizers
used. The amount of TEC in coating formulation significantly effected drug release (p < 0.001), but the effect of PEG 6000 was not significant. Formulations containing PEG 6000 released more drug (98.35 ± 2.35%)
than TEC (68.01 ± 1.04%) after 24 h. Different kinetic models like zero order, first order, and Higuchi were used for fitting
drug release pattern. Zero order model fitted best for diclofenac release in all formulations. Drug release mechanism was
derived with Korsmeyer equation. 相似文献
17.
Richard A. Anderson Noella A. Bryden Marilyn M. Polansky 《Biological trace element research》1992,32(1-3):117-121
Chromium content of 22 daily diets, designed by nutritionists to be well-balanced, ranged from 8.4 to 23.7 μg/1000 cal with
a mean ±SEM chromium content of 13.4±1.1 μg/1000 cal. Most dairy products are low in chromium and provide <0.6μg/serving.
Meats, poultry, and fish are also low in chromium, providing 2 μg of chromium or less per serving. Chromium contents of grain
products, fruits, and vegetables vary widely, with some foods providing >20 μg/serving. In summary, chromium content of individual
foods varies, and is dependent upon chromium introduced in the growing, transport, processing, and fortification of the food.
Even well-balanced diets may contain suboptimal levels of dietary chromium. 相似文献
18.
The level and/or form of dietary iron, dietary nickel, and the interaction between them affected the trace element content
of rat liver. Livers were from the offspring of dams fed diets containing 10–16 ng, or 20 μg, of nickel/g. Dietary iron was
supplied as ferric chloride (30 μg/g) or ferric sulfate (30 μg, or 60 μg). In nickel-deprived rats fed 60 μg of iron/g of
diet as ferric sulfate, at age 35 days, levels of iron and zinc were depressed in liver and the level of copper was elevated.
At age 55 days, iron was still depressed, copper was still elevated, but zinc also was elevated. In rats fed 30 μg of iron/g
of diet as ferric chloride, liver iron content was higher in nickel-deprived than in nickel-supplemented rats at 30, but not
at 50, days of age. Also manganese and zinc were lower in nickel-deprived than in nickel-supplemented rats at age 35 days
if their dams had been on experiment for an extended period of time (i.e., since age 21 days). Thus, the levels of copper,
iron, manganese, and zinc in liver were affected by nickel deprivation, but the direction and extent of the affects depended
upon the iron status of the rat. 相似文献
19.
Wang X Schlossmacher U Wiens M Schröder HC Müller WE 《Marine biotechnology (New York, N.Y.)》2009,11(1):99-108
Polymetallic/ferromanganese nodules (Mn-nodules) have been assigned a huge economic potential since they contain considerable
concentrations of manganese, copper, nickel, iron, and cobalt. It has been assumed that they are formed by, besides hydrogenous,
nonbiogenic processes, biogenic processes based on metabolic processes driven by microorganisms. In the present study, we
applied the techniques of digital optical microscopy and high-resolution scanning electron microscopy to search for microorganisms
in Mn-nodules. They were collected from the Clarion-Clipperton Zone in the Eastern Pacific Ocean and are composed of Mn (23.9%),
Cu (0.69%), Ni (1.02%), Fe (10.9%), and Co (0.29%). These Mn-nodules, between 2.3 and 4.8 cm, show a distinct lamination;
they are composed of small-sized micronodules, 100 to 450 μm in size, which are bound together by an interstitial whitish
material. In the micronodules, a dense accumulation of microorganisms/bacteria could be visualized. Only two morphotypes exist:
(1) round-shaped cocci and (2) elongated rods. The cocci (diameter: ≈3.5 μm) are arranged in bead-like chains, while the rods
(≈2 × 0.4 μm) are arranged either as palisades or in a linear row. Energy-dispersive X-ray spectroscopy analyses showed that
the areas rich in microorganisms/bacteria are also rich in Mn, while in regions where no microorganisms are found, the element
Si is dominant. We suggest that growth of the Mn-nodules starts with the formation of “micronodules.” The formation of micronodules
is assumed to be mediated by microorganisms. After accretion of biogenic and additional nonbiogenic minerals, the micronodules
assemble to large nodules on the sea floor through additional inclusion of nonbiogenic material. 相似文献
20.
Matthew D. Lebar Lisha Luttenton James B. McClintock Charles D. Amsler Bill J. Baker 《Polar Biology》2011,34(4):587-590
The vanadium, manganese, and nickel contents of nine species of Antarctic tunicates were determined by atomic absorption spectroscopy.
The Antarctic species Distaplia cylindrica contained significantly more vanadium (1,445 ppm dry weight) than the other Antarctic tunicates investigated. Antarctic Ascidia sp. was also shown to accumulate considerable amounts of vanadium (567 ppm). Low levels of bioaccumulated manganese (<50 ppm)
and nickel (<15 ppm) were observed in all tunicates examined. 相似文献