Residue levels of organochlorine pesticides in some ecosystem components of Manzala Lake

To evaluate the organochlorine pesticide (OCP) contamination of Manzala Lake, its ecosystem was investigated during the winter season (December to March). The studied ecosystem components were water, sediment, aquatic weeds, and fishes in four locations. The samples were analyzed by gas chromatography with electron capture detector. Pollutant levels of total OCPs showed significantly high levels in the water areas of Round road (46.253 ng/ml), Port-Said Damietta road (19.301 ng/ml), followed by Bughas El-Rasoah (5.539 ng/ml), then Ashtoum El Gamel (natural reserve area now) (0.289 ng/ml). Organochlorines were detected in sediment only in Round road (3.359 μg/kg) and Port-Said Damietta road (0.171 μg/kg) by significant order while they were undetectable in Ashtoum El Gamel and Bughas El-Rasoah. Total OCPs in aquatic weeds ranged between 0.194 μg/kg in Port-Said Damietta and 0.026 μg/kg in Ashtoum El Gamel. While OCPs were 0.160 and 0.153 μg/kg in Round road and Bughas El-Rasoah, respectively. Concerning fish muscles OCPs were significantly higher in the Round road area (0.397 μg/kg) followed by the Port-Said Damietta road (0.258 μg/kg), and finally, Ashtoum El Gamel samples (0.126 μg/kg). The results revealed the direct relation for the accumulation of OCPs between studied ecosystem parameters at the Manzala Lake during the winter season. Results also demonstrated that fish samples collected from the Manzala Lake in the studied areas were contaminated with levels of organochlorines, not higher than the maximum permissible level recorded by FAO/WHO, and that the public is not at risk with fish consumption.     

COMPARATIVE STUDY OF FRESH-SALT WATER INTERFACES USING FINITE ELEMENT AND SIMPLE APPROACHES

ABSTRACT: The fresh-salt water interface in artesian aquifers has been investigated by various techniques on the basis of its analogy to the free surface in earth dams or cores of dams. Although various approximations are used, some more or less exact solutions exist. One of the simple methods, that would appeal to practical workers, was developed by the analysis of hydraulic forces. However, this method has not been checked thoroughly due to the lack of wide ranges of coverage by the more or less exact solutions. In this paper a suggested finite element method is used for the purpose of comparing with the method of hydraulic forces. The presented procedure eliminates some of the difficulties and uncertainties in current finite element procedures. Both methods proved to be in close agreement. Moreover, the hydraulic heads along the upper boundary of the artesian aquifer were found to be in close agreement with Dupuit's equation. The results of this investigation would greatly simplify the more complex management problems when the effects of discharge and/or recharge wells are added to the natural flow effects.     

Experimental study of the stack geometric parameters effect on the resonance frequency of a standing wave thermoacoustic refrigerator

Thermoacoustic refrigeration is an emerging technology that makes use of acoustic power to pump heat. The resonance frequency is important for the performance of thermoacoustic refrigerators, as it affects the temperature difference across the stack. This paper aims to optimize the performance of thermoacoustic refrigerators by experimentally investigating the effect of the stack geometric parameters (i.e. stack position, stack length, and the stack size) on the resonance frequency of a standing wave loudspeaker driven thermoacoustic refrigerator. Celcor Ceramic stacks of normalized positions of 0.764, 1.05, 1.43, and 1.72, normalized lengths of 0.076, 0.114, 0.153, and 0.191, and two porosities of 0.8 and 0.85 are used. The clarification of the relationship between the stack geometric parameters and the resonance frequency of the thermoacoustic refrigerator is presented. Moreover, the coefficient of performance of the thermoacoustic refrigerator is observed to increase at the resonance frequency of each stack configuration.     

GLOBAL WATER ISSUES AND THE WORLD WATER COUNCIL1

ABSTRACT: The key events and the process that led to the creation of the World Water Council on World Water Day 1996 are reviewed and its characteristics summarized. The development of this new organization is discussed in the context of the major global trends in water and water-related issues, viz. growing water scarcity with its links to limits on food production and demographic patterns. In response to the need to find solutions to these pressing water issues, the development of a Technical Program based on the deliberations of the founding member organizations and a number of short-term activities have been outlined to demonstrate the evolution of the Council in this first year of its existence. Given the importance of complementarity between the Council and the Global Water Partnership, an attempt has been made to articulate the mutually-reinforcing roles of the two organizations.     

Recovery of aluminium, nickel-copper alloys and salts from spent fluorescent lamps

This study explores a combined pyro-hydrometallurgical method to recover pure aluminium, nickel-copper alloy(s), and some valuable salts from spent fluorescent lamps (SFLs). It also examines the safe recycling of clean glass tubes for the fluorescent lamp industry. Spent lamps were decapped under water containing 35% acetone to achieve safe capture of mercury vapour. Cleaned glass tubes, if broken, were cut using a rotating diamond disc to a standard shorter length. Aluminium and copper-nickel alloys in the separated metallic parts were recovered using suitable flux to decrease metal losses going to slag. Operation variables affecting the quality of the products and the extent of recovery with the suggested method were investigated. Results revealed that total loss in the glass tube recycling operation was 2% of the SFLs. Pure aluminium meeting standard specification DIN 1712 was recovered by melting at 800 degrees C under sodium chloride/carbon flux for 20 min. Standard nickel-copper alloys with less than 0.1% tin were prepared by melting at 1250 degrees C using a sodium borate/carbon flux. De-tinning of the molten nickel-copper alloy was carried out using oxygen gas. Tin in the slag as oxide was recovered by reduction using carbon or hydrogen gas at 650-700 degrees C. Different valuable chloride salts were also obtained in good quality. Further research is recommended on the thermodynamics of nickel-copper recovery, yttrium and europium recovery, and process economics.     

Pyruvate-utilizing bacteria as potential contributors to the food web in the Arabian Gulf

Water samples from the Kuwaiti coasts of the Arabian Gulf were used for counting and isolating bacteria capable of growth on low molecular weight organic compounds known to be released by picocyanobacteria. The compounds tested were potassium acetate, sodium pyruvate, fumaric acid, succinic acid, sodium citrate and glycerol. For comparison, the bacterial numbers on glucose (a conventional carbon source) and Tween 80 and crude oil (unconventional carbon sources), as sole sources of carbon and energy were also determined. Sodium pyruvate was, in most cases, the carbon and energy source most commonly utilized by the cultivable surface water bacteria. The most common cultivable bacterial genera on the test carbon sources were Pseudoalteromonas, Vibrio, Cobetia and Roseobacter. Less common genera were Rhodococcus, Pseudomonas and Bacillus. Quantification of heterotrophic bacteria associated with cultures of local picocyanobacterial strains, originally isolated from the Gulf surface water, also revealed that the carbon source most commonly utilized by cultivable bacteria was sodium pyruvate. However, a different bacterial composition was identified, with Alcanivorax, Stappia and Marinobacter as the major heterotrophic genera. All heterotrophic bacteria that grew on sodium pyruvate could also grow on β-alanine, as sole sources of carbon and energy. From this study we suggest that the Arabian Gulf bacteria utilizing picocyanobacterial low molecular weight compounds, particularly pyruvate may potentially contribute to the food web in this aquatic system. The experiments comply with the current laws of Kuwait.     

Discovering and characterizing farm households’ resilience under water scarcity

Water scarcity at an alarming rate has been a limiting factor for sustainable agriculture in arid and semi-arid environments of the world. It has resulted in a number of problems such as poverty and food insecurity among farm households. Therefore, building and improving resilience, as a way to mitigate the impacts of water scarcity, is important for farm households. But one of the significant steps for planning to improve farm households’ resilience under water scarcity is investigation of the current level of resilience of these households and understanding their variances. Therefore, this study offers a classification of farm households’ diversity based on resilience. Primary data were collected from 260 randomly selected farm households in 21 villages around Parishan wetland, Iran. Farm Household Resilience Scale was used to measure resilience. Cluster analysis suggested three groups: highly, medium-, and low-resilient farm households. The results of comparing three groups revealed that highly resilient farm households characterize with higher risk management, more agricultural water security, more positive psychological traits, and better knowledge management. Also, they had better water quality, attended more agricultural extension activities, and used modern irrigation systems. Farm households’ resilience map using GIS software illustrated that there is a relationship between resilience and farm location from the wetland. The findings of this study could be used by planner and policy-makers to improve farm households’ resilience in arid and semi-arid environments. Improvement in knowledge management system is recommended as one of the most effective policy instruments in building resilience.     

Spatial distribution of heavy metals in soils of the flood plain of the Seversky Donets River (Russia) based on geostatistical methods

Environmental Geochemistry and Health - Soil contamination by heavy metals (HM) is a worldwide problem for human health. To reduce risk to human health from exposure to toxic chemicals associated...