Kinetics of copper desorption from soils as affected by different organic ligands

Desorption of Cu and low molecular weight dissolved organics are the primary factors that impact fate and transport of Cu in soils. To improve predictions of the toxicity and threat from Cu contaminated soil, it is critical that time-de pen dent desorption behavior be understood. In this paper, the effect of organic ligands citrate, malate, and succinate on the kinetics of Cu desorption from contaminated soils varying widely in soil characteristics was investigated at 25°C and the soils used were referred to as clay, calcareous and sandy soils. The amount of Cu released by the used organic ligands varied greatly with physicochemical properties of the soils. The rate of Cu release by different extractants was in the order citric > malic > succinic, which was consistent with the stability constants of Cu complexes with these ligands. The modified Freundlich and the Elovich and Parabolic diffusion models were used to describe dsorption of Cu[+2] from the three studied soils as affected by the organic ligands. All of the models fit the data well with correlation coefficients ranging from 0.83 to 1.00 [P < 0.01]. Each Model has a set of assumptions for the different physical and chemical properties of the systems to which they are being applied. The uses of these equations yield different magnitudes for the calculated variable, but the relation ships between the soil + organic ligands and their effect [i.e., increase or decrease] on these variables are the same. Such information is critical, since Cu is used in a variety of industrial and manufacturing processes and is one of the most common contaminants found at hazardous waste sites

Drinking water treatment residuals as an amendment to alkaline soils: effects on the growth of corn and phosphorus extractability

Drinking water treatment residuals [alum] are waste products of water purification that have potential for environmental remediation as a soil amendment and a potential plant growth medium. In this study, the influence of added Drinking water treatment residuals on the extractability and availability of phosphorus to plants; determination of the agronomic rate of alum to different agricultural soils and evaluation of the alum as ameliorating material for soil conditions and plant growth were investigated. In all studied soils, increasing drinking water treatment residuals rate up to 30 g/kg significantly increased dry matter yield. Application of 10, 20 and 30 g/kgalum significantly increased plant P concentrations in the plant materials [shoots and roots] taken from clay, sandy and calcareous soils. Further increase in alum application rate has resulted in negative significant impact on plants P concentration, especially in clay and calcareous soils, but in sandy soils the increase in phosphorusconcentration extended to 40 g/kg alum rate. Application of alum at rates up to 30 g/kg significantly increased available phosphorus concentrations of the three studied soils. However, application of alum at a rate of 40 g/kg to clay and calcareous soils significantly decreased available phosphorus concentrations. Combined analyses of all soils and alum rates studied clearly indicated significant relationship between available phosphorus concentration and phosphorus uptake [r = 0.87, P < 0.001]. Based on our experiment results, the rate of 30 g/kg is considered the best application rate of alum because of its positive effects on plant dry matter. Our study clearly demonstrates that alum has potential as a soil amendment to increase plant growth; however, more research is needed to determine beneficial and / or detrimental aspects of this practice under field conditions

Radioprotective role of vitamin E and testosterone against radiation effects on serum cholesterol and free fatty acids of irradiated rats

The present study has been carried out to evaluate the radioprotective efficiency of vitamin E and testosterone for protecting the levels of serum total cholesterol and free fatty acids from deleterious radiation effects. Whole body gamma irradiation of rats at the dose of 7 Gy induced significant increase in the level of serum total cholesterol. This increase was 35.9, 103.3, 46.3, 47.3 and 40.0% on the 1st, 3rd, 7th, 10th and 14th days post irradiation respectively, as compared to normal control values. As for free fatty acids content, a significant decrease was observed at the 3rd and 14th days post irradiation, while insignificant changes were recorded on the 1st, 7th and 10th days after irradiation. The treatment of rats with intraperitoneal injection of either vitamin E or testosterone pre-whole body gamma irradiation reduced the changes induced in the levels of studied parameters. The observed recovery was more clearly pronounced in the rats treated with vitamin E than in treated rats with testosterone

Prophylactic action of testosterone on lipid metabolism of liver and serum in gamma irradiated albino rats

The present study has been carried out to investigate the efficiency of testosterone as a radioprotector agent. The levels of total lipids and triglycerides as well as the lipolytic activity of liver and serum in gamma irradiated rats were selected for this study at periods of 1, 3, 7, 10 and 14 days post irradiation.The results indicated that whole body gamma irradiation at the dose of 7 Gy caused different significant changes in the levels of total lipids and triglycerides of the liver. However an evident elevation in serum total lipids and triglyceride contents produced at all post irradiation days. The enzymatic activity of serum and liver lipase significantly increased on the 3rd and 7th days post-irradiation and decreased at the other experimental times. Pre-treatment of rats with testosterone, 10 days, before whole body gamma irradiation [7 Gy] has minimized the variation occurred in the levels of the studied parameters in both liver and serum