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The impact of adding a natural clay sorbent such as halloysite on the content of selected heavy metals in the biomass of common orchardgrass (Dactylis glomerata L.) was studied in a pot experiment. The study was conducted on mucky soil enriched anthropogenically with heavy metals, whose values exceeded permissible standards of soil quality and values of the geological background. The experiment included three variants with differentiated percentage of halloysite, i.e. 10%, 30% and 50%, as well as two control cultivations. The results confirm the impact of halloysite on the physicochemical properties of soil, consisting in increased soil pH and sorption capacity. Addition of halloysite to soil also differentiated the quantity of crop yield and concentration of heavy metals in the plant and soil. Halloysite was found to have an inconsistent impact on the concentration of heavy metals in the biomass of common orchardgrass, which was proven by some elevation in the level of heavy metals and a higher bioaccumulation factor (BAF). Halloysite constituting 50% of the mass of substrate substantially increased the consumption of Pb and reduced the sorption of Cr. Addition of halloysite stabilised Zn and Cu in soil. The results of our preliminary investigation indicate that addition of halloysite to soils with excessive concentrations of heavy metals influences the level of soil sorption to the extent which may be effective for soil remediation.
In the present paper, we have presented a theoretical discussion of specific biophysical mechanisms per taining to the regulation (by means of internal factors) of physiological water ex change with the water medium by the cells of the Nitella translucens. The investigation has demonstrated that these cells have a capacity for water ex change regulation through changes in the values of transport parameters of the cell membrane (i.e. the filtration coefficient Lp and the reflection coefficient σ), as well as changes in the concentration Csi (in side the cells) of the osmotically active solute.
In this work the energetics of water transport along the radial path of bean root (Phaseolus vulgaris L) and water elevation along the xylem induced by osmotically generated root pressure was studied. The radial path of the root was, according to Fiscus's concept [1,2], approximately modelled by a 1-membrane system. An analytical method by Kargol [5] (concerning the osmo-diffusive conversion of free energy) and data from a work by Steudle [9] (on permeation parameters of the root, i.e., filtration coefficient Lp, reflection coefficient a and permeability coefficient co) were applied in this study. This work shows that the energetical efficiency of the root of that plant does not depend on concentration, C0 of the root bathing solution (the medium) within the concentration range: 0
Each living cell must, while performing its life functions, constantly exchange water with its surroundings. This occurs through the cell membrane. In the present paper, we have made an attempt to explain the biophysical basis of this water exchange, realized under stationary conditions, i. e. at constant cell volume. For the investigation, the mechanistic equations for membrane transport have been applied. It has been demonstrated that each living cell which subsists under stationary conditions is capable of water absorption and simultaneous water removal to its surroundings. Water absorption is osmosis-driven, while water removal is driven by the mechanical pressure difference (the turgor pressure). These are new, and very significant, research results. This stationary water exchange cannot be explained on the basis of thermodynamic transport equations.
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