A rapid procedure is described for the separation of plutonium radionuclides from large volumes of fresh and saline water
by means of a manganese dioxide coprecipitation technique. This procedure has been used in the laboratory and in the field
to process 50 to 400 liter water samples. Plutonium is carried through an oxidation and reduction step to insure complete
equilibration between added yield tracers and the plutonium present in the water sample. Average recovery under optimum conditions
has been 80% for seawater and over 90% for freshwater samples processed in the field with simple equipment. The procedure
can be used also to separate plutonium from water samples by direct adsorption on MnO2-impregnated cartridges. Under laboratory conditions the adsorption on MnO2 was independent of the oxidation states of plutonium in aqueous samples.
Within a 300 x 600 m
complex heterogeneous sodic grassland two techniques were compared for
assessing soil salinity. The standard technique is based on repeated field
instrumental measurements at 420 points. The alternative technique was
performed with the use of numerical simulation of salt accumulation carried out
on 3 profiles. These profiles have been selected as representatives of the
distinct classes, or map strata of salt accumulation, distinguished with
preliminary statistical clustering of the instrumental measuring points.
Simulated values were extrapolated for the 3 strata distinguished. The maps
obtained with the two techniques were statistically correlated. The use of
numerical simulation is cost-effective. Further improvements are expected from
a combination of improved numerical simulation and utilization of more strata.
Authors:Hong-Xiang Zhao, Bao-Huai Wang, and You-Min Zhang
The thermal curves and the enthalpy changes of the interaction between some oral sustained release preparations (Contac, Fenbid
and Benza sustained release capsules) and physiological saline have been measured at 298.15 K with a MS-80 standard Calvet
microcalorimeter. The curves that recorded the changes of heat effect with time have clearly shown the sustained release action
and process of the above preparations. A method for examining the sustained release action of sustained release preparations
can be developed from the above experiments. The principle of application and the experimental procedure of this method have
been expounded, and some results of the above experiments have also been discussed.
Authors:A. Laissaoui, J. Abril, R. Periáñez, M. León, and E. Montaño
In estuarine environments there are important spatial and temporal changes in both salt and suspended load concentrations.
An experimental procedure have been developed to produce kinetic parameters being representative of the natural environment
studied, and we have investigated the effect of salinity and suspended load concentration to the kinetics of the uptake. These
results are encouraged by recent advances in environmental modelling concerning to radionuclide dispersion in aquatic natural
systems and involving non-equilibrium processes. Experiments are carried out with unfiltered water samples from the Odiel
estuary (Southwest of Spain), with133Ba tracer to illustrate experimental procedures.
Authors:C. Maucieri, C. Caruso, S. Bona, M. Borin, A. C. Barbera, and V. Cavallaro
In many world regions, osmotic and salt stresses are becoming the primary environmental conditions limiting successful establishment of crops. The old durum wheat landraces may provide a source of genes useful to enhance crop resilience to the abiotic stresses of dryland areas or foreseen as a result of climate change. With this in mind, in order to determine the effects of salt and osmotic stresses on durum wheat germination, an old Sicilian durum wheat landrace “Timilia” and a relatively recent cultivar “Mongibello” were investigated at various iso-osmotic solutions of NaCl and mannitol at osmotic potentials of: 0 – control, –0.125, –0.250, –0.500 and –0.750 MPa.
Under stress conditions, different germination and early growth behavior was observed in the two durum wheat genotypes. Timilia presented almost stable germination even at the highest osmotic stresses (96.7% and 88.3% seed germination at 0 and –0.750 MPa, respectively) showing a higher capacity of seed imbibition than Mongibello. The latter thus showed a higher sensitivity than the old landrace to the studied stresses. The variability ascertained in the response to salinity stress indicate that Timilia could be a source of interesting genes for breeding programs.
Authors:C. Kaya, N.A. Akram, M. Ashraf, and O. Sonmez
Application of salt stress (100 mM) through root growing medium caused a considerable decrease in plant fresh and dry biomass, maximum quantum yield (Fv/Fm), chlorophyll contents, leaf water potential, and leaf Ca, K, P and N concentrations of two maize cultivars (Apex 836 and DK 5783). However, salt-induced increase was observed in leaf osmolality (LO), proline, hydrogen peroxide (H2O2), malondialdehyde (MDA), Na+ concentration and activities of enzymatic antioxidants, such as catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD). Of five humic acid (HA) levels used under non-stress and stress conditions in an initial experiment, 100 mg L−1 was chosen for subsequent studies. Exogenous application of humic acid (HA) at the rate of 100 mM as a foliar or pre-sowing seed treatment significantly increased the plant biomass, Fv/Fm, chlorophyll pigments and proline contents, while it considerably reduced the leaf water potential, H2O2 and MDA contents as well as the activities of all the afore-mentioned enzymatic antioxidants. Of both modes of exogenous treatment, foliar spray was better in improving plant biomass, chlorophyll contents, LO, leaf Na+ as well as the accumulation of all nutrients measured, however, in contrast, seed pre-treatment was more effective in altering leaf proline, H2O2 and MDA contents. Of both maize cultivars, cv. DK 5783 excelled in plant biomass, chlorophyll contents and leaf N, Ca and K concentrations as well as in the activities of all three antioxidant enzymes, whereas cv. Apex 836 was superior in leaf Na+ and P concentrations, H2O2 and MDA contents. Cv. DK 5783 was comparatively better in salt tolerance as compared to cv. Apex 836. Overall, exogenous application of HA was effective in improving salinity tolerance of maize plants which can be attributed to HA-induced increase in plant biomass, chlorophyll contents, mineral nutrients and activities of key antioxidant enzymes.