Valorization of treated olive mill wastewater in fertigation practice.

Olive mill wastewater (OMW) brings about a major environmental problem in Tunisia as well as in the other Mediterranean countries. Its strong organic load and its toxicity due to the presence of complex phenolic compounds have dire effects when applied to soil. To overcome this difficulty, the OMW pretreatment was investigated in the present work using the Fenton oxidation reaction with zero-valent iron. Then, this pretreated wastewater was valorized in fertigation practice. The effects of the addition of different concentrations of both treated and raw OMW on soil and cropping system were investigated. The treatment by Fenton oxidation with zero-valent iron could reduce 50 % of COD and decrease 53 % of phenolic compounds. OMW application had a temporary effect on the soil pH and EC. The results showed that the evolution of soil pH and EC was related to the organic matter of the soil which depends on the spread concentrations of raw or treated OMW. After 15-day incubation period, the soil pH and EC tended to stabilize and return to the control level. Moreover, this stabilization is faster in treated OMW than that in raw OMW especially for concentrations as high as 3 and 4 %. Plants cultivated with treated OMW showed an increase in their germination. The results pointed an improvement in the stem length of plants which is almost similar to that of the control for both pea and tomato, especially for high concentrations of 3 and 4 %.

Effect of phosphogypsum on growth, physiology, and the antioxidative defense system in sunflower seedlings.

Phosphogypsum (PG) is the solid waste product of phosphate fertilizer production and is characterized by high concentrations of salts, heavy metals, and certain natural radionuclides. The work reported in this paper examined the influence of PG amendment on soil physicochemical proprieties, along with its potential impact on several physiological traits of sunflower seedlings grown under controlled conditions. Sunflower seedlings were grown on agricultural soil substrates amended with PG at rates of 0, 2.5, and 5 %. The pH of the soil decreased but electrical conductivity and organic matter, calcium, phosphorus, sodium, and heavy metal contents increased in proportion to PG concentration. In contrast, no variations were observed in magnesium content and small increases were recorded in potassium content. The effects of PG on sunflower growth, leaf chlorophyll content, nutritional status, osmotic regulator content, heavy metal accumulation, and antioxidative enzymes were investigated. Concentrations of trace elements in sunflower seedlings grown in PG-amended soil were considerably lower than ranges considered phytotoxic for vascular plants. The 5 % PG dose inhibited shoot extension and accumulation of biomass and caused a decline in total protein content. However, chlorophyll, lipid peroxidation, proline and sugar contents, and activities of antioxidant enzymes such as superoxide dismutase and catalase increased. Collectively, these results strongly support the hypothesis that enzymatic antioxidation capacity is an important mechanism in tolerance of PG salinity in sunflower seedlings.

Effects of cadmium on lipids of almond seedlings (Prunus dulcis).

BACKGROUND: Cadmium uptake and distribution, as well as its effects on lipid composition was investigated in almond seedlings (Prunus dulcis) grown in culture solution supplied with two concentrations of Cd (50 and 150 µM). RESULTS: The accumulation of Cd increased with external metal concentrations, and was considerably higher in roots than in leaves. Fourteen days after Cd treatment, the membrane lipids were extracted and separated on silica-gel thin layer chromatography (TLC). Fatty acid methyl esters were analyzed by FID-GC on a capillary column. Our results showed that Cd stress decreased the quantities of all lipids classes (phospholipids, galactolipids and neutral lipids). Galactolipid, phospholipid and neutral lipid concentrations decreased more in roots than in leaves by Cd-treatment. In almost all lipid classes the proportion of palmitic acid (16:0), linoleic (18: 2) and that of linolenic (18: 3) acid decreased, suggesting that heavy metal treatment induced an alteration in the fatty acid synthesis processes. CONCLUSIONS: In conclusion, our results show that the changes found in total fatty acids, in the quantities of all lipids classes, and in the in the profiles of individual polar lipids suggest that membrane structure and function might be altered by Cd stress.

Factors associated with pulmonary edema in severe scorpion sting patients--a multivariate analysis of 428 cases.

OBJECTIVE: To determine clinical and routine laboratory factors associated with pulmonary edema secondary to scorpion envenomation. DESIGN AND SETTING: Retrospective study covering 13 years (1990-2002) in the medical Intensive Care Unit of a university hospital (Sfax-Tunisia). PATIENTS: 428 patients older than 3 years who were admitted to the intensive care unit for scorpion envenomation were included in this study. Patients were stratified into two groups according to the presence or absence of pulmonary edema as assessed by a medical committee. MEASUREMENTS AND RESULTS: The mean (+/- SD) age was 17.5 +/- 17.7 years, ranging from 3 to 76 years. The pulmonary edema group included 294 patients (68.7%). A multivariate analysis found the following factors to be correlated with a pulmonary edema: age less than 5 years (p = 0.04), sweating (p = 0.004), agitation (p = 0.01), leukocytes of 25000 cells/mm3 or more (p = 0.02), and a plasma protein concentration of 72 g/L or more (p < 0.0001). In addition, a plasma protein concentration of 72 g/L or more predicted the presence of pulmonary edema with a sensitivity of 78% a specificity of 88%, a positive predictive value of 93%, and negative predictive value of 64%. Almost 84% of patients having a respiratory rate of > or = 30 breaths/minute associated with agitation and sweating were classified in the pulmonary edema group. This clinical association indicates the presence of pulmonary edema with a specificity of 84.3% and a positive predictive value of 87.5%. CONCLUSION: In scorpion envenomation patients older than 3 years, the association of a respiratory rate of > or = 30 breaths/minute, agitation, sweating, or the presence of high plasma protein concentrations suggest the presence of pulmonary edema.