Polycyclic aromatic hydrocarbons (PAHs) in surface sediments from the Bizerte Lagoon,Tunisia: levels,sources, and toxicological significance

To assess the status of polycyclic aromatic hydrocarbon (PAH) contamination in sediments from the Bizerte Lagoon (northern Tunisia), 18 surface sediment samples were collected in March 2011 and analyzed for 14 US Environmental Protection Agency priority PAHs by high-performance liquid chromatography. The total concentrations of the 14 PAHs (ΣPAHs) ranged from 16.9 to 394.1 ng g^?1 dry weight (dw) with a mean concentration of 85.5 ng g^?1 dw. Compared with other lagoons, coasts, and bays in the world, the concentrations of PAHs in surface sediments of the Bizerte Lagoon are low to moderate. The PAHs’ composition pattern was dominated by the presence of four-ring PAHs (45.8 %) followed by five-ring (26.8 %) and three-ring PAHs (12.7 %). The PAH source analysis suggested that the main origin of PAHs in the sediments of the lagoon was mainly from pyrolytic sources. According to the numerical effect-based sediment quality guidelines of the USA, the levels of PAHs in the Bizerte Lagoon should not exert adverse biological effects. The total benzo[a]pyrene toxicity equivalent values calculated for the samples varied from 3.1 to 53.7 ng g^?1 dw with an average of 10.6 ng g^?1 dw.     

Physiological and biochemical defense reactions of Vicia faba L.–Rhizobium symbiosis face to chronic exposure to cyanobacterial bloom extract containing microcystins

The presence of cyanotoxins, mainly microcystins (MCs), in surface freshwater represents a serious health risk to aquatic organisms living in the water body, as well as terrestrial animals and plants that are in contact with contaminated water. Consequently, the use of MCs contaminated water for irrigation represents a hazard for cultivated plants and could induce severe economical losses due to crops’ yield reduction. The experimental approach undertaken in this work was exposing Vicia faba seedlings (inoculated with a Rhizobium strain resistant to MCs), to water supplemented with cyanobacterial crude extract containing total microcystins at a concentration of 50 and 100 μg/L (environmental relevant concentrations of MCs dissolved in the raw irrigation water from Lalla Takerkoust Lake-Marrakesh region). After chronic MCs exposure (2 months), biological and physiological parameters (plant growth, nitrogen uptake, mineral assimilation, and oxidative defense mechanisms) were evaluated. The results obtained showed evidence that chronic exposure to cyanobacterial bloom extract containing MCs strongly affected the physiological and biological plants activities; reduction of dry matter, photosynthetic activity, nodule number, and nitrogen assimilation. At the same time, an increase of oxidative stress was observed, as deduced from a significant increase of the activities of peroxidase, catalase, polyphenoloxidase, and phenylalanine ammonia lyase in leaves, roots, and nodules of faba bean plants exposed to cyanotoxins, especially at 100 μg/L of MCs. This experimentation constitutes a simulation of the situation related to cyanotoxins chronic exposure of seedlings—plants via the contaminated irrigation water. For this reason, once should take into consideration the possibility of contamination of agricultural crops and the quality of irrigation water should be by the way monitored for cyanotoxins biohazard.     

Public opinion and siting solid waste landfills in Kuwait

Siting municipal solid waste landfills in Kuwait had not considered public concerns about the location of such facilities. Kuwait Municipality has disposed urban waste in abandoned sand quarries for the past 20 years in an unplanned fashion. Due to this improper siting criteria, environmental and health problems have risen from old landfills that are located in residential areas. In an effort to help responsible decision-makers in assessing public support for siting landfills a structured, yet simple, questionnaire was designed and distributed to a random sample of heads of households. Statistical techniques were employed to examine trends and relationships between the sample public responses concerning landfill siting criteria. The findings of the research indicated that a significant percentage of the responding sample did not know about the various landfill impacts and less than 50% were aware of the negative impacts of landfills on the public health and the environment. The visual appearance of the landfill scored the lowest impact in the opinion of the sample public while the most important aspect in siting a landfill appeared to be its economic consideration. The research findings also directed attention to the important role that the media could play in increasing public awareness. Results from the cross-classification analysis demonstrated the existence of differences in awareness levels according to age, nationality, martial status, education, and occupation of the responding sample. Statistically, these differences were significant at the 95% significance level, as supported by the test of the χ-square.     

Investigation the effect of adding graphene oxide into diesel/higher alcohols blends on a diesel engine performance

ABSTRACT

This article aims to study the influence of the addition of graphene oxide nanoparticles (GO) to diesel/higher alcohols blends on the combustion, emission, and exergy parameters of a CI engine under various engine loads. The higher alcohols mainly n-butanol, n-heptanol, and n-octanol are blended with diesel at a volume fraction of 50%. Then, the 25 and 50 mg/L concentrations of GO are dispersed into diesel/higher alcohols blends using an ultrasonicator. The GO structures are examined using TEM, TGA, XRD and FTIR. The findings show that there is a reduction in p_max. and HRR when adding higher alcohols with diesel fuel. Regarding engine emission, there is a significant improvement in emissions formation with adding higher alcohols. The addition of GO into diesel/higher alcohols blends improves the brake thermal efficiency by 15%. Moreover, the p_max. and HRR are both enhanced by 4%. The CO, UHC and smoke formation are reduced considerably by 40%, 50 and 20%, respectively, while NO_x level is increased by 30% with adding GO. Finally, adding high percentages of n-butanol, n-heptanol, and n-octanol with diesel fuel with the presence of GO has the potential to achieve ultra-low CO, UHC, and smoke formation meanwhile keeping high thermal efficiency level.     

Seasonal variations of aerosol residence time in the lower atmospheric boundary layer

During a one year period, from Jan. 2002 up to Dec. 2002, approximately 130 air samples were analyzed to determine the atmospheric air activity concentrations of short- and long-lived (222Rn) decay products 214Pb and 210Pb. The samples were taken by using a single-filter technique and gamma-spectrometry was applied to determine the activity concentrations. A seasonal fluctuation in the concentration of 214Pb and 210Pb in surface air was observed. The activity concentrations of both radionuclides were observed to be relatively higher during the winter/autumn season than in spring/summer season. The mean activity concentration of 214Pb and 210Pb within the whole year was found to be 1.4+/-0.27 Bq m(-3) and 1.2+/-0.15 mBq m(-3), respectively. Different 210Pb:214Pb activity ratios during the year varied between 1.78 x 10(-4) and 1.6 x 10(-3) with a mean value of 8.9 x 10(-4) +/- 7.6 x 10(-5). From the ratio between the activity concentrations of the radon decay products 214Pb and 210Pb a mean residence time (MRT) of aerosol particles in the atmosphere of about 10.5+/-0.91 d could be estimated. The seasonal variation pattern shows relatively higher values of MRT in spring/summer season than in winter/autumn season. The MRT data together with relative humidity (RH), air temperature (T) and wind speed (WS), were used for a comprehensive regression analysis of its seasonal variation in the atmospheric air.     

Preparation of aluminium-magnesium alloys and some valuable salts from used beverage cans

The purpose of this work is to recover standard aluminium-magnesium alloy(s) and some valuable salts from used beverage cans (UBCs). The suggested method updated the current recycling technology by augmenting removal of the coating paint, decreasing magnesium loss during melting process and improving hydrochloric acid leaching of the formed slag. Iron impurity present in the leaching solution, was removed by oxidation using oxygen gas or hydrogen peroxide and filtered as goethite. Results obtained revealed that a mixture of methyl ethyl ketone/dimethyl formamide entirely removes the paint coating at room temperature. The process compares favorably to the current methods involving firing or swell peeling. The coating decomposes to titanium dioxide by heating at 750 degrees C for 30 min. Standard compositions of Al-Mg alloys are formulated using secondary magnesium. The extent of recovery (R) of these alloy(s) is a function of the melting time and temperature and type of the flux. The maximum (R) value amounts to 94.4%. Sodium borate/chloride mix decreases magnesium loss to a minimum. The extent of leaching valuable salts from the slag increases with increasing the molarity, stoichiometric ratio and leaching temperature of the acid used. Removal of iron is a function of the potential of the oxidation process. Stannous chloride has been recovered from the recovered and dried salts by distillation at 700-750 degrees C.     

Activity concentration of caesium-137 in agricultural soils

In this study, we measured 137Cs activity concentrations in the soil samples taken from agricultural lands in the Buyuk Menderes Basin in Turkey in 1997 and 1998. The soil samples were collected from 42 sites in this Basin. The activity concentration of 137Cs was found to range between 2.81+/-0.17 Bq.kg(-1) and 20.75+/-0.29 Bq.kg(-1). The effect of organic matter, clay, silt and sand contents and pH of the soil on the relative adsorption of the 137Cs on the soil surface were also studied.     

Uranium bioassay and radioactive dust measurements at some uranium processing sites in Egypt--health effects

The safety of radiation workers in the uranium mining industry requires close and continuous monitoring of their working conditions. In this study, external radiation surveillance, radioactive dust monitoring and the bioassay of uranium were carried out in some processing sites. As dust represents one of the most important sources of radiation exposure in mills and mines, dust monitoring and bioassays were performed for a sample of workers on the production lines. The concentration of uranium in air ranged from 22.6 x 10(-7) to 11.1 x 10(-5) Bq cm-3, and the exposure levels ranged from 1 to 80 microSv h-1. Laser fluorimetric determination of uranium in urine samples showed concentrations in the range 8.4-29.2 micrograms L-1. Renal function parameters, such as serum creatinine and urea, and hematological parameters were determined in an attempt to correlate them with radiation exposure and the health status of the workers. Urine specimens collected from workers at the ore crushing and separation site showed elevated concentrations of uranium (up to 29.2 micrograms L-1) and a strong correlation between these concentrations and the registered serum creatinine. The mean uranium excretion in the investigated group was more than 20 times the occupational exposure decision level for urine uranium of 0.8 microgram L-1.