Risk assessment of heavy metal toxicity of soil irrigated with treated wastewater using heat shock proteins stress responses: case of El Hajeb,Sfax, Tunisia

Heavy metal contamination of soil resulting from treated wastewater irrigation can cause serious concerns resulting from consuming contaminated crops. Therefore, it is crucial to assess hazard related to wastewater reuse. In the present investigation, we suggest the use of biomarker approach as a new tool for risk assessment of wastewater reuse in irrigation as an improvement to the conventional detection of physicochemical accumulation in irrigated sites. A field study was conducted at two major sites irrigated with treated wastewater and comparisons were made with a control site. Different soil depths were considered to investigate the extent of heavy metal leaching, the estrogenic activity, and the biomarker response. Results have shown that a longer irrigation period (20 years) caused a slight decrease in soil metal levels when compared to the soil irrigated for 12 years. The highest levels of Cr, Co, Ni, Pb, and Zn were detected at 20 and 40 cm horizons in plots irrigated with wastewater for 12 years. The latter finding could be attributed to chemical leaching to deeper plots for longer irrigation period. Furthermore, the treated wastewater sample showed a high estrogenic activity while none of the soil samples could induce any estrogenic activity. Regarding the stress response, it was observed that the highest stress shown by the HSP47 promoter transfected cells was induced by a longer irrigation period. Finally, the treated wastewater and the irrigated soils exhibited an overexpression of HSP60 in comparison with reference soil following 1 h exposure. In conclusion, in vitro techniques can be efficiently used to assess potential hazard related to wastewater reuse.     

Pesticide residues in fruits and vegetables from Pakistan: a review of the occurrence and associated human health risks

The main objective of the review is to document, assess and analyze the results of the previously reported data on levels of different pesticides in selected fruits and vegetables from Pakistan. The findings of the previous studies clearly indicated that more than 50 % of the samples were contaminated with organophosphate, pyrethroids and organochlorine pesticides. Many studies reported that among fresh fruits and vegetables tomato, apple, melon, mango, grapes, and plum crossed the FAO/WHO permissible limits for these contaminants residual levels. The comparison of other regions showed that observed levels were found above maximum residue limits (MRLs) in 50 % of the samples but were in agreement with the studies from neighboring countries like China and Bangladesh. Higher hazard risk index (HRI) values were calculated for dieldrin, methamidophos, o,p′-DDT, diazinon and p,p′-DDT in apple, mango, banana, melon, potato and onion. The review also highlights that data on pesticide residues in foodstuff is scarce which should be overcome by further extending studies from different areas of Pakistan. In order to ascertain the provision of food suitable for human consumption, it is imperative to monitor pesticides in food commodities by the country’s authorities and enforce guidelines based on permissible limits.     

Preparation and characterization of mesoporous γ-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> recovered from aluminum cans waste and its use in the dehydration of methanol to dimethyl ether

The present study includes synthesis of two γ-Al₂O₃ samples from waste aluminum cans using a simple precipitation method. Precipitation was carried out using two different precipitating agents (i.e. NaOH and NH₄OH). The two prepared alumina samples were characterized by means of X-ray diffraction (XRD) and N₂ adsorption–desorption techniques. Surface acidity of γ-Al₂O₃ samples was measured by adsorption of two different probe molecules (i.e. pyridine and dimethyl pyridine) followed by desorption measurements using thermogravimetry (TG) and differential scanning calorimetry (DSC) techniques. Catalytic activity of the two prepared alumina samples towards the dehydration of methanol (to dimethyl ether) was studied in a fixed bed reactor at 300 °C. For comparison reasons, commercial γ-Al₂O₃ sample was, also, tested for the same catalytic reaction under the same conditions. Results showed that the alumina sample prepared using NaOH as a precipitating agent exhibited a better catalytic activity and stability compared with that prepared using NH₄OH and showed a similar activity as the commercial γ-Al₂O₃ sample.     

Review on the innovative uses of steel slag for waste minimization

Piles of steel slag, a solid waste generated from the iron and steel industry, could be seen due to no utility found for the past century. Steel slag has now gained much attention because of its new applications. The properties of slag greatly influence its use and thus had got varied applications. The chemical composition of steel slag varies as the mineral composition of raw material such as iron ore and limestone varies. This paper reviews the characteristics of steel slag and its usage. The paper reviews recent developments in well-known applications to the steel slag such as aggregate in bituminous mixes, cement ingredient, concrete aggregate, antiskid aggregate, and rail road ballast. This paper also reviews novel uses such as mechanomutable asphalt binders, building material, green artificial reefs, thermal insulator, catalyst and ceramic Ingredient. The review is also done on utilization of solid waste for waste management by the novel methods like landfill daily cover material, sand capping, carbon sequestration, water treatment and solid waste management. Review also shows recovery of pure calcium carbonate and heavy metals from slag, providing opportunity for revenue generation. Steel slag once traded as free to use by steel industries is now sold in the market at some price. Its utilization is of great economic significance as it also contributes to the reduction of solid waste.     

A study on the combined effect of noise and vibration on operators' performance of a readability task in a mobile driving environment.

This paper presents a study in which the main objective was to investigate the combined effect of noise and vibration on the performance of a readability task in a mobile driving environment. Subjects performed a readability task on a laptop computer in a sitting posture with their backs supported with a backrest under varying levels of noise and vibration. The data in terms of the mean number of characters read per minute were collected and statistically analyzed. Results showed that the individual effect of noise, vibration, and the operators' gender as well as the interaction between gender and noise, and gender and vibration were statistically significant. However, the combined effect of noise and vibration was not found to be statistically significant. Results also indicated that gender was statistically significant at all levels of noise as well as vibration, and noise and vibration were statistically significant at both levels of gender.     

Inactivation of pathogenic micro-organisms in hospital waste using a microwave

The aim of this study was to investigate the efficiency of dry sterilization by microwave in the inactivation of pathogenic bacteria in blood wastes. Eight bacteria strains were selected for this purpose and these are S. aureus, Salmonella sp., E. faecalis, K. pneumonia, P. aeruginosa, E. coli, Streptococcus Group B and Bacillus sp. Sterilization by microwave was carried out at 385, 450 and 700 watts for 1, 5 and 10 min, respectively. Isolation and enumeration of pathogenic bacteria before and after treatments were carried out using direct plate technique and inactivation was determined in terms of log reduction. Increasing the running time and power to 10 min and 700 watts did not increase log reduction of most of pathogenic bacteria especially of gram negative bacteria. Revival of pathogenic bacteria during the storage period might be aided by the presence of a low moisture content which helps bacterial cells to revive but not to reproduce or over-grow. It can be concluded that dry sterilization of blood wastes by microwave reduces the number and limited re-growth of these pathogenic bacteria during storage time, due to the lower moisture content in the blood wastes.     

Protective role of a methanolic extract of spinach (Spinacia oleracea L.) against Pb toxicity in wheat (Triticum aestivum L.) seedlings: beneficial effects for a plant of a nutraceutical used with animals

Spinach extracts contain powerful natural antioxidants and have been used to improve the response of animal cells to various stress factors. The aim of the present study was to assess the effects of a methanolic extract of spinach (SE) used at two concentrations (21.7 and 217 ppm) on the growth, certain enzymes and antioxidant systems in wheat seedlings under lead stress. When wheat seedlings were grown for 7 days in a solution containing Pb(NO₃)₂ (3 mM), germination and growth were impaired, while signs of oxidative stress were observed. SE (217 ppm) pretreatment was able to protect seedlings from Pb toxicity by both reducing Pb uptake and Pb-induced oxidative stress. As a consequence, almost normal germination, elongation, biomass and α-amylase activity were restored by SE (217 ppm) pretreatment of wheat seedlings, in spite of the presence of Pb. Our results support the protective role and the antioxidant effect of SE against Pb. These results show an amazing similarity to the effects of SE in animals, which suggests that providing “nutraceuticals” to plants could improve their “health” status.