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61.
Inorganic-N concentrations in soil solution of whole tree harvest (WTH) and conventional fell (CF) plots were monitored for two years before felling and four years after felling. Concentrations in the mineral soil after felling were higher than in standing forest for up to 14 months in both felling treatments. In the WTH plots inorganic-N concentrations then dropped steadily until four years after felling they approached zero. In contrast, inorganic-N concentrations of the CF plots remained comparatively large. Inorganic-N was dominated by nitrate throughout the period of the study, and especially in the mineral horizons.Felling debris was not a source of inorganic-N, unless indirectly through release and mineralisation of soluble organic-N. Vegetation cover, biomass and N content were substantially greater in the WTH plots two to three years after felling, compared with the CF. Vegetation cover and brash cover (slash cover in N. America) were negatively correlated. There was also a negative correlation between inorganic-N concentration in soil water samplers and the vegetation cover within the collection area of, or a 1 m square surrounding, these samplers.Two factors are probably responsible for the reduction in inorganic-N concentrations after felling in the WTH — the rapid re-establishment of vegetation and the lack of a N source in felling debris. In the CF plots, brash prevents re-establishment of vegetation over wide areas for at least four years. However, brash is not directly a source of inorganic-N at this stage. 相似文献
62.
Momoko Chiba Masakazu Kikuchi Chiharu Tohyama Masataka Nishikawa 《Biological trace element research》1990,25(2):137-147
To study effects of simultaneous administration of tin (Sn) and selenium (Se) on concentrations of several essential elements, mice were injected with either SnCl2 (ip) or Na2SeO3 (sc), alone or both compounds at a daily dose of 5 mumol/kg each for 12 consecutive days. Mice were sacrificed at 20 h after the last injection and concentrations of Sn, Se, Na, Ca, Zn, P, Fe, K, and Mg in the liver, kidney, spleen, pancreas, testis, seminal vesicle, lung, femoral muscle, and femoral bone were determined. In the control mice, Sn and Se concentrations were the highest in bone (0.69 micrograms Sn and 6.93 micrograms Se/g dry wt). Administered Sn was found to accumulate in all organs except the testis. Among the essential elements determined, Na was the most affected in terms of concentration in the organs and Mg was the least affected element in these organs. Among the organs tested, each elemental concentration in the pancreas was most affected. Simultaneous injections of Sn and Se appeared to keep the correlation coefficients between elements similar to those found in the control mice. 相似文献
63.
64.
The relationships among inorganic carbon transport, bicarbonate availability, intracellular pH, and culture age were investigated in high-calcifying cultures of Emiliania huxleyi (Lohmann) Hay & Mohler. Measurement of inorganic carbon transport by the silicone-oil centrifugation technique demonstrated that gadolinium, a potential Ca2+ channel inhibitor, blocked intracellular inorganic carbon uptake and photosynthetic 14CO2+ fixation in exponential-phase cells. In stationary-phase cells, the intracellular inorganic carbon concentration was unaffected by gadolinium. Gadolinium was also used to investigate the link between bicarbonate and Ca2+ transport in high-calcifying cells of E. huxleyi. Bicarbonate availability had significant and rapid effects on pHi in exponential- but not in stationary-phase cells. 4′, 4′-Diisothiocyanostilbene-2,2′-disulfonic acid did not block bicarbonate uptake from the external medium by exponential-phase cells. Inorganic carbon utilization by exponential- and stationary-phase cells of Emiliania huxleyi was investigated using a pH drift technique in a closed system. Light-dependent alkalization of the medium by stationary-phase cells resulted in a final pH of 10.1 and was inhibited by dextran-bound sulphonamide, an inhibitor of external carbonic anhydrase. Exponential-phase cells did not generate a pH drift. Overall, the results suggest that for high-calcifying cultures of E. huxleyi the predominant pathway of inorganic carbon utilization differs in exponential and stationary phase cells of the same culture. 相似文献
65.
66.
67.
Hair samples of 23 male professional drivers and 20 male university teachers in Hong Kong were collected, and the concentrations of Al, Sb, As, Ca, Cu, Fe, Pb, Mg, Mn, Hg, K, Sr, S, V, and Zn were measured. Both of the target groups fell within the same age group of 35–45. The washing method of using detergent and powder was found to be comparable to that of using ether. Difference in the mean concentration of each detected element in the two groups was tested by the Student'st-test and the Wilcoxon rank-sums test. Hair concentrations of Al, Sb, Pb, Mg, Mn, and K in the «Driver Group» were significantly (p<0.05) higher than those in the “Teacher Group.” On the other hand, As and Hg were found to have a higher concentration in hair of teachers. Interpretation of the findings in terms of the environmental factor and the metabolic rate was attempted. 相似文献
68.
Analysis of variance, analysis of covariance, correlation coefficient, multiple correlation, and partial correlation coefficient
statistical tests were applied to Cs, Cr, Co, Fe, Rb, Sc, Se, and Zn content in human ovaries in order to evaluate statistically
the possible relationships between these trace elements at: the ovary as an organ, each ovarian phase separately, each morphological
part independent of the ovarian phase, and between cortex and medulla within the ovarian phases. The element Cs seems to have
a homogenous distribution between cortex and medulla within reproductive and menopausal phase. Zinc shows a trend to have
an antagonistic relation with Cs, Cr, Co, and Fe during fetal and reproductive phases and not during menopausal phase. The
relationship between Zn and Cs when Fe is kept constant could be used as a tool for the decontamination of the ovary from
an abnormal Cs content or for the inhibition of the accumulation of the same element to the ovarian tissue. 相似文献
69.
James K. Friel Claude Mercer Wayne L. Andrews Brian R. Simmons Simon E. Jackson 《Biological trace element research》1996,54(2):135-142
Contamination in a trace element laboratory can come from a variety of sources, including laboratory gloves. Therefore, vinyl
and latex gloves were obtained from as many manufacturers as would supply gloves. These gloves were either prepared for acid-washing
and subsequent soaking in an acid solution, or immersed in an acid solution for a duration of either 1 min or 1 h. Incubation
washes were analyzed for a variety of trace elements by flame atomic abosrption spectroscopy (AAS) or inductively coupled
mass spectrometry (ICP-MS). Results indicated that only three brands of vinyl gloves were acceptable for use in a trace element
laboratory, whereas others had contamination of different elements. Latex gloves contained such high levels of biologically
important elements that they were not considered suitable for routine trace element work. Vinyl gloves of choice should be
routinely acid-washed before use in a trace element laboratory. 相似文献
70.
Trace elements and lipid peroxidation in 26 patients with chronic renal failure treated with hemodialysis and 25 healthy subjects
were observed. Both plasma and erythrocyte trace elements and plasma malon dialdehyde (MDA) were examined immediately before
and after hemodialysis. Increased levels of plasma Cu, MDA, and erythrocyte Pb, Mn, Zn, and a significantly decreased plasma
Se, Zn and erythrocyte Se were found in patients before hemodialysis. After a single hemodialysis, erythrocyte Mn, Cu, Zn,
and plasma Cu, Al, and MDA were significantly increased whereas both plasma and erythrocyte Se were lower in patients than
in healthy subjects. The level of MDA was not significantly changed during the single hemodialysis. Both plasma and erythrocyte
Zn levels and plasma Cu and Al were significantly higher after hemodialysis than before hemodialysis. In conclusion, levels
of trace elements are altered by hemodialysis, which may increase patient susceptibility to lipid peroxidation in uremia. 相似文献