Partitioning of radiostrontium in marine aqueous suspensions: laboratory experiments and modeling studies

Quantitative information on the adsorption/desorption of radionuclides by suspended loads is important in the study of their environmental behavior. In this paper, controlled laboratory experiments were directed at studying the kinetic transfer and final distribution of radiostrontium in aqueous suspensions using 85Sr as tracer. The results showed that the uptake of 85Sr in seawater can be properly described by one reversible-reaction model. However, in the absence of competitive cations, it has been shown that two reactions of different characteristic times are unambiguously involved in the kinetic evolution of adsorption. Thus, a modeling approach consisting of three-box model has been applied. The model predicts in a satisfactory way the time evolution of activities in the dissolved phase and two sites in the particles. Experimental evidence showed, through comparison among kinetic and distribution coefficients corresponding to different conditions, that Ca2+ affects strongly the rate and extent of Sr uptake by suspended particles. On the other hand, distribution coefficients were found to be sensitive to changes in suspended particulate matter (SPM) concentration, exhibiting a reverse effect with this parameter on the adsorption. In addition, desorption from particles is important showing that Sr can be easily released due to cation-exchange processes.     

Gamma aminobutyric acid radioreceptor‐assay a possible biomarker for human exposure to certain agrochemicals

Abstract

Cyclodiene insecticides, hexachlorocyclohexanes, pyrethroids, bicyclophosphates, the bicycloorthocarboxylate insecticides and some of their metabolites and environmental degradation products are central nervous system toxicants with high specific binding affinity to the chloride channel of the γ‐ aminobutyric acid (GABA)_A receptor‐ionophore sites. [³⁵S] tertiary‐butylbicyclophosphorothionate (TBPS) with specific activity higher than 60 Ci/mmole has a high binding affinity to the same sites and is now commercially available and can be used to label the GABA_A receptor for the development of a radioreceptor assay technique. The GABA receptor was prepared by ultra centnfugation and dialysis of brain homogenates of either cow, goat, rat or catfish. The receptor was then labeled with [³⁵S] TBPS and the assay was conducted by measuring the displacement of radioactivity following incubation with samples containing the analytes. A radioreceptor assay protocol was developed to measure the amount of the α‐endosulfan in blood samples. The assay was extremely sensitive, and can detect 0.2 nM of endosulfan at a level equivalent to 0.08 ppb or 8x10^‐11 gm of endosulfan in each ml of the blood samples.     

Effects of two organophosphorus insecticides on some biochemical constituents in the nervous system and liver of rabbits

Abstract

Male Baladi rabbits were acutely and sub‐chronically intoxicated with cyanofenphos and profenophos. The levels of cholesterol, triglycerides, B‐lipoproteins and total proteins were determined in the serum, brain, spinal cord and sciatic nerve of rabbits. Moreover, the activities of alkaline phosphatase, acid phosphatase and glutamic‐pyruvic transaminase were determined in the liver of the animals. The whole Studie revealed that the biochemical constituents were highly affected by the tested insecticides. Also, the liver function suffered from adverse effects of the tested insecticides.     

Pb in medicinal plants from Jordan

This is the first report on Pb in medicinal herbs from Jordan. Medicinal herbs may present a health risk due to the presence of toxic metals. Seventy-nine dry medicinal plant samples were collected from herbalist shops in Jordan. The plants were digested with acids and analyzed for total Pb concentration using atomic absorption spectrometry. Mean Pb concentration was 15.9 μg/g on a dry weight basis. Our results show that Pb concentrations in Jordan medicinal plants are higher than published data in other countries. The highest level of 33.4 μg Pb/g was determined in Inula viscosa, and the lowest level of 3.0 μg Pb/g was found in Nigella sativa. Calculated daily intakes of Pb of most analyzed herbs were high; most of them are higher than recommended values by the world health organization (WHO). Fortunately, the herbs that contain the highest Pb levels are the less commonly used medicinal herbs in Jordan. The mean Pb levels in the most commonly, commonly and less commonly used herbs in Jordan are 13.9, 13.1 and 16.9 μg Pb/g, respectively. The average dietary intake of Pb through a mixture of these medicinal herbs consumption, assuming 5.0 g herbs is consumed daily, is 79.5 μg Pb/day, which is higher than the maximum daily limit allowed by WHO. We conclude that most of the medicinal plants consumed in Jordan contain significant amount of Pb, and therefore, people of Jordan should not consume large amounts of these herbs.     

The performance of Electro-Fenton oxidation in the removal of coliform bacteria from landfill leachate

Leachate pollution is one of the main problems in landfilling. Researchers have yet to find an effective solution to this problem. The technology that can be used may differ based on the type of leachate produced. Coliform bacteria were recently reported as one of the most problematic pollutants in semi-aerobic (stabilized) leachate. In the present study, the performance of the Electro-Fenton process in removing coliform from leachate was investigated. The study focused on two types of leachate: Palau Borung landfill leachate with low Coliform content (200 MPN/100 m/L) and Ampang Jajar landfill leachate with high coliform content (>24 × 10⁴ MPN/100 m/L). Optimal conditions for the Electro-Fenton treatment process were applied on both types of leachate. Then, the coliform was examined before and after treatment using the Most Probable Number (MPN) technique. Accordingly, 100% removal of coliform was obtained at low initial coliform content, whereas 99.9% removal was obtained at high initial coliform content. The study revealed that Electro-Fenton is an efficient process in removing high concentrations of pathogenic microorganisms from stabilized leachate.     

Legislative aspects of pesticide regulations

Abstract

This paper reviews the development of pesticides as an agricultural and health tool and discusses the national and international implications of pesticide regulation. The need for scientific input to the legislative and regulative processes is explained. Appropriate legislation and regulatory structures are presented. Finally, the need for international cooperation in the use and control of pesticides is analyzed.     

Trace element content in tea brewed in traditional metallic and stainless steel teapots

The migration of metals in tea brewed in metallic teapots was investigated. The teapots were obtained from North Africa stores in Brussels in 2005–2006 and in 2011. Chinese gunpowder green tea, the most commonly used tea in the Moroccan community, was used to prepare the tea. Tea brewed in metallic teapots was compared to tea brewed in a glass vessel in order to evaluate the contribution of the tea and the teapots to the metal concentrations in the brewed tea. Tea samples were also collected in Moroccan households and in tearooms in Brussels. The elements As, Cd, Pb, Sn, Mn, Fe, Cr, Co, Ni, Cr, Cu, Zn, and Al were analyzed by high-resolution sector field inductively coupled mass spectrometry. The relationship between the metal composition of the alloy of the teapot and the metal concentration in tea was also investigated. Migration of Pb and to a lesser amount Ni, Cu, and Zn was observed in brass teapots and migration of Cd from a number of stainless steel teapots was observed. The soldering connecting the sprout to the teapot was shown to be an important source of Pb to the tea. High levels of Mn and Al were also observed in the brewed tea and these elements where shown to originate from the tea itself. Metal exposure from tea drinking was calculated for different tea consumption levels and different metal concentration levels and compared to toxicological reference values.     

Beach impacts of shore-parallel breakwaters backing offshore submerged ridges, Western Mediterranean Coast of Egypt

Seven breakwaters were constructed behind offshore submerged ridges to create a safe area for swimming and recreational activities west of Alexandria on the Mediterranean coast of Egypt. Morphodynamic evaluation was based on the modified Perlin and Dean numerical model (ImSedTran-2D) combined with successive shoreline and beach profile surveys conducted periodically between April 2001 and May 2005. Results reveal insignificant morphologic changes behind the detached breakwaters with slight coastline changes at the down and up-drift beaches of the examined breakwaters (+/-10 m). These changes are associated with salient accretion (20-7 0m) in the low-energy leeside of such structures. Concurrent with this sand accretion is the accumulation of a large amount of benthic algae (Sargassum) in the coastal water of the shadow area of these structures, which in turn have adverse effects on swimmers. Practical measures proposed in this study have successfully helped in mitigating such accumulation of algae in the recreation leeside of the breakwaters. The accumulation of Sargassum, together with the virtual insignificant changes in the up-drift and down-drifts of these structures, is a direct response to both coastal processes and the submerged carbonate ridges. Coastal processes encompass reversal of the directions of long-shore sand transport versus shoreline orientation, the small littoral drift rate and sand deficiency of the littoral zone. The beach response to the breakwaters together with the submerged ridges has also been confirmed by applying the ImSedTran-2D model. Results indicate that submerged ridges play a principal role in the evolution of beach morphology along the west coast of Alexandria. Although the study area is exposed to more than 70% wave exposures, the morphodynamic behavior of the beaches indicates that the submerged ridges act in a similar way as an additional natural barrier together with the artificial detached structures.     

Metabolism of DDT in different tissues of young rats

The bioconcentration and distribution pattern of p,p'-DDT 1,1,1-1trichloro-2,2-bis(2-chlorophenyl-4-chlorophenyl)-ethane] and its main metabolites (p,p'-DDD [1,1-dichloro-2,2-bis (4-chlorophenyl) ethane] and p,p'-DDE [1,1-dichloro-2,2-bis (4-chlorophenyl) in adipose tissue, liver, brain, kidney, thymus, and testis were examined in young rats after 10 days of intraperitoneal injection of 50 and 100 mg of p,p'-DDT/kg of body weight. Analyses were performed by high-resolution gas chromatography. p,p'-DDT was found to be accumulated in a dose-dependent manner with the highest concentration in adipose tissue. However, in brain, the accumulation of pesticide was low and remained unchanged at the higher dose. This difference may relate to the protective role of the blood-brain barrier, which limits the access of the xenobiotic in the cerebral compartment, and to the differential tissue lipid composition. Although tissues concentration of p,p'-DDE and p,p'-DDD correlated positively to total p,p'-DDT levels, the active role in detoxification of pollutants may explain why p,p'-DDD is more abundant in liver than in the rest of organs. On the contrary, in brain, the concentration of p,p'-DDE is higher than that of p,p'-DDD, suggesting that the metabolism of the parent insecticide proceeds via more than one pathway.