Nutrient concentrations in current and 1-year-old needles were analyzed annually for 5 years after application of hardened wood ash in 1–4-year-old Norway spruce (Picea abies (L.) Karst.) stands within a range of climate and fertility gradients. At each site, 3000 kg ha–1 hardened wood ash of two types, Nymölla and Perstorp, was applied in a randomized block design. Wood ash Nymölla contained 12 kg ha–1 P, 30 kg ha–1 K, 891 kg ha–1 Ca, 72 kg ha–1 Mg and wood ash Perstorp contained 12 kg ha–1 P, 60 kg ha–1 K, 486 kg ha–1 Ca, and 60 kg ha–1 Mg. The ash was intended to compensate for nutrients removed at the preceding harvest when logging residues were collected and removed from the site (whole-tree harvesting). The climate gradient included four climate zones throughout Sweden and each of these included a fertility gradient of three sites classified according to their ground vegetation type. There were no effects on nutrient concentrations in the needles 1 year after the application of wood ash. Five years after ash application, the concentrations of P, K and Ca in current and 1-year-old needles were higher than in the control plots. The results were consistent over all stands, irrespective of climate zone and fertility status. P and K concentrations were higher in spruce needles from plots treated with Perstorp wood ash, whereas Ca concentrations were higher in those of Nymölla treated plots. Analyses across all study sites revealed a treatment effect in terms of increased ratios of P:N, K:N and Ca:N in 1-year-old needles. The ratio P:N tended to increase with time in the Perstorp wood ash treatment compared with the control. The needle concentrations of Mg and S were not affected by the ash applications. The increase in needle nutrient concentrations after application of hardened wood ash suggests that wood ash recycling could be used in order to replace nutrients removed at whole-tree harvesting. 相似文献
Ash samples were collected from a dumping site (fly ash) and an electrostatic precipitator (ESP ash) of a 440 MW thermal power plant for characterization. Analysis of ash samples showed that the major matrix elements in fly ash were Si and Al, together with significant percentages of K, Fe, Ca and Mg. Some of the biologically-toxic elements, Ni, Cr, Pb, B and Mo, were also present in substantial amounts. Ash collected directly from electrostatic precipitator (ESP ash) was finer in texture, lower in pH and generally richer in nutrients than the ash collected from dumping sites (fly ash). The saturation moisture percentages of both the ashes were higher, but the bulk density was lower, than the normal cultivated soils. Calcium was the dominant cation of the exchange complex, followed by Mg2+, Na+ and K+. Contents of available sulphur were quite high. Among DTPA extractable micronutrients, only iron was present in significant amounts, but the contents of hazardous constituents were very low. Compositions of watersoluble constituents of both the ashes were substantially affected by water: fly ash ratio and decreased with dilution. The rate of release of sodium was found to be much less than calcium and magnesium. 相似文献
In this study the nature and occurrence of two circulating polysaccharide antigens of Schistosoma mansoni, circulating anodic antigen (CAA) and circulating cathodic antigen (CCA), and the immunological response to these antigens in mouse, hamster, and human infections were investigated. Both CAA and CCA showed a large molecular weight range, less than 50,000 to over 300,000 for CAA and 50,000 to over 300,000 for CCA, possibly representing monomers and polymers. CAA and CCA could be purified from the trichloroacetic acid-soluble fraction of adult worm antigen (AWA-TCA) by means of DEAE ion exchange chromatography. The presence of at least two other components in AWA-TCA was shown. Both CAA and CCA were found to be gut associated, and could be demonstrated in the vomitus and in the excretory and secretory antigens of adult worms. Both antigens were present in the kidney eluates of infected hamsters, while CCA could normally be detected in the urine of these hamsters and CAA only occasionally. CAA was demonstrated in the Kupffer cells of the livers of infected mice and hamsters. Antibodies against CAA and CCA were shown in mouse, hamster, and human infections. In human infections specific IgM titers against these antigens were especially elevated in children and in recent infections of adults. 相似文献
This study investigated a solidification treatment process for soils that are contaminated with hydrocarbons at levels of 0.5 and 3.0% by weight of benzene. The contaminated soils were bound in a concrete matrix and the migration of organics from the concrete to air was evaluated. If the hydrocarbon emissions are sufficiently attenuated, the concrete containing such contaminated soil can be used for exterior construction applications.
The experimental specimens consisted of concrete mixtures in which 40% of the sand was replaced with the contaminated soil. The mixtures’ ratio of cement, aggregate, sand, and water is 1:1.5:1.5:0.5 by weight. The study included specimens with and without class C fly ash replacing 10% of the cement. In addition, two unfixed control specimens were prepared for each contamination level. The concrete‐soil mixtures were placed in sealed jars and air was passed through the head space of the jars and then through carbon adsorption tubes for measurement of contaminant flux from the surface of the specimens. Measurements were made during and after concrete curing. The results were fitted to a Fickian diffusion model to estimate effective diffusivity in the concrete‐soil specimens.
The test results showed that the effective diffusivity of the contaminant within the concrete was reduced by three to five orders of magnitude over the molecular diffusivities in unfixed contaminated soil used as control. It was observed that the presence of fly ash in the concrete affects the hydrocarbon release and causes an additional decrease in effective diffusivity of about one order of magnitude. Contaminant emissions during the curing phase were found to exceed rates predicted by the Fickian model. This is apparently due to the water used in the concrete. Total emissions, however, never exceeded values emitted from the unfixed controls. This study indicates that fixation of low hydrocarbon levels within concrete is a technically viable and safe technology for recycling petroleum‐contaminated soil. 相似文献
The gravimetric density of humeri, radii, femora and tibiae from a series of 274 male and female skeletons of rhesus monkeys, Macaca mulatta, was determined for fetal, young and adult periods. The ages of 171 of the animals were known: they ranged from 57 days of gestation to 13.6 years; the ages of an additional 103 skeletons were estimated. The mean density of the fetal bones was found to increase linearly with age and was higher for males than females, and higher for the superior than for the inferior limb bones. During the young period the pattern of increase in density can be represented by a power-type curve, and the density is significantly higher in females than in males and in superior than in inferior limb bones. The densities of the long limb bones of the adult skeletons show a slight, but not significant, negative trend with increasing age. In this age group the mean densities are higher for males than females and higher for the superior than for the inferior limb bones. The percentage ash weight was determined for the total skeleton and for 21 subdivisions of 23 postnatal skeletons with estimated ages. The skull and long limb bones were found to have higher mean percentage ash weights than the vertebral segments and the sternum. Both the density and the percentage ash weight of the Macaca mulatta skeletons examined exceed those found in our earlier studies of the human skeleton. 相似文献