Toxic Effect of a Pesticide, Diflubenzuron on Freshwater Microinvertebrate (Tetrahymena pyriformis)

Harmful bugs affect food production,directly by the qualitativeor quantitative reduction of the harvests,or indirectly while servinglike vectors of several illnesses of the plants and human[1].Many chemical products are used by human for a long time inthe…     

Quantitative assessment of desertification in south of Iran using MEDALUS method

The main aim of this study was the quantitative assessment of desertification process in the case study area of the Fidoye-Garmosht plain (Southern Iran). Based on the MEDALUS approach and the characteristics of study area a regional model developed using GIS. Six main factors or indicators of desertification including: soil, climate, erosion, plant cover, groundwater and management were considered for evaluation. Then several sub-indicators affecting the quality of each main indicator were identified. Based on the MEDALUS approach, each sub-indicator was quantified according to its quality and given a weighting of between 1.0 and 2.0. ArcGIS 9 was used to analyze and prepare the layers of quality maps using the geometric mean to integrate the individual sub-indicator maps. In turn the geometric mean of all six quality maps was used to generate a single desertification status map. Results showed that 12% of the area is classified as very severe, 81% as severe and 7% as moderately affected by desertification. In addition the plant cover and groundwater indicators were the most important factors affecting desertification process in the study area. The model developed may be used to assess desertification process and distinguish the areas sensitive to desertification in the study region and in regions with the similar characteristics.     

Analysis of polychlorobiphenyls from used transformers for polychlorodibenzofurans

The results of analyses for polychlorodibenzofuran (PCDF) content in two samples of polychlorobiphenyl (PCB) from used electrical transformers are presented and discussed. In neither sample was there evidence for enhanced PCDF concentrations even though one of them had been subjected to overheating while in service.     

Polychlorodibenzo-p-dioxins and dibenzofurans in technical pentachlorophenol - results of a collaborative analytical exercise

Results of analyses of eight samples of technical pentachlorophenol conducted by three different analytical methods are presented and discussed.     

Long term changes in polychlorodibenzo-p-dioxin concentrations in wood treated with technical pentachlorophenol

Wood samples treated with technical pentachlorophenol (PCP), technical sodium pentachlorophenoxide (NaPCP) and octachlorodibenzo-p-dioxin have been exposed outdoors for periods up to $\text{2}\text{1}\text{2}$ years. Analysis of extracts from the samples show that photolytic reductive dechlorination of highly chlorinated dibenzo-p-dioxins to less chlorinated isomers occurs. However there is no discernible increase in polychlorodibenzo-p-dioxin concentrations in the technical PCP treated wood presumably because further photolytic reactions and volatilisation compete effectively with the photolytic formation. There is no evidence for formation of octachlorodibenzo-p-dioxin (OCDD) in technical PCP treated wood in this study, probably because photolytic destruction and volatilisation compete effectively with formation reactions when the initial OCDD concentration is relatively high.     

Investigation of wind erosion process for estimation, prevention, and control of DSS in Yazd–Ardakan plain

Wind erosion is a phenomenon that is reasonably common in regions where dry winds blow. For the most part, these regions correspond to the dry lands; areas where the soil, generally, is dry and shifting and lacks vegetation for most of the year. The winds are sufficiently strong to lift and move sands and soil particles. The repeated removal of superficial layers by the action of winds can modify the texture of the topsoil, by removing the fine particles and leaving the larger particles. Dust and sandstorm (DSS) is the generic term for a serious environmental phenomenon that involves strong winds that blow a large quantity of dust and fine sand particles away from the ground and carry them over a long distance with significant environmental impacts along the way. In the realm of DSS in Iran country, the people who live in Yazd and Sistan–Baluchestan provinces form a single ecological community due to their geographic proximity and climatic contiguity. The major sources of DSS in the region are believed to be the desert and semidesert areas of the Yazd–Ardakan plain in Yazd province. Both Sistan and Baluchestan are the recipients of this dust. To address the long-range transboundary environmental problem of DSS, a regional cooperation mechanism must be established among the provinces in the region. Yazd–Ardakan plain, with area of about 650,000 ha, is located in the center of Iran, between Yazd and Ardakan cities. The mean annual rainfall is less than 65 mm. Rainfall distribution is a simple modal and more than 70% of it occurs in winter. Plant density varies from 0% to 25%, and Artemisia sieberi is the dominant plant species. The major part of Yazd–Ardakan plain is bare land. According to the recent investigation, more than 20,000-m³ dust with less than 100-μm diameter falls down annually on Yazd city with an area of 7,000 ha. Horizontal visibility is reduced to less than 6 m in stormy days in some parts of Yazd–Ardakan plain. This phenomenon causes car accidents on the main roads of Yazd–Ardakan and can cancel the airplane flights in the stormy days. At present, it is estimated that wind erosion causes more than $6.8 million damages to socioeconomic resources in Yazd plain each year. This paper describes the pattern of occurrence of wind erosion and major contributing factors, summarizes measured rates of wind erosion, outlines the techniques used to mitigate wind erosion hazard, and suggests research priorities. Also, damages of DSS have been estimated and methods for prevention and control are suggested.