Journal of Environmental Studies
Year:2011 | Volume:37 | Issue:59|Papers Count:21

Polycyclic aromatic hydrocarbons (PAHs) are globally distributed environmental contaminants which attract considerable attention because of their known toxic and bioaccumulative effects on animals. They are among the most carcinogenic, mutagenic and toxic contaminants found in most coastal areas of the world. PAHs with two rings are more soluble in water and more volatile than PAHs with three rings or more, which have low solubility in water and a low vapor pressure. As molecular weight increases, the solubility and vapor pressure of PAHs decrease, while the carcinogenicity increases. Thus, heavier PAHs become more toxic and lipophilic. Sixteen individual PAH compounds have been identified as high-priority pollutants by the United States Environmental Protection Agency (USEPA) due to their toxic, mutagenic and carcinogenic properties.

Disposal of human sewage has become a necessity for societies, today. The construction of treatment plants has caused problems with huge contents of dry sludge. It has been found that each person produce 35 to 85 grams of solid sludge per day.In recent years, waste production has increased dramatically in developing nations such as Iran. There are two methods for the disposal of solid waste (dry sludge) including landfilling and using the sludge as fertilizer. Both of these methods have been prohibited by Iran's Environmental Organization, due to the dangers of heavy metals present in the sludge. Due to these limitations, high volumes of dry sludge have been produced and collected in treatment plants.

One of the serious problems in human communities will be the shortage of drinking water resources in future. The development of fresh water fish culture is a deteriorating factor to this problem. Ammonia (NH3) and nitrite (NO2) are toxic chemicals resulting from fish culture, especially in intensive fish culture systems. Low concentrations of Ammonia make physiological and morphological changes in aquatic organisms, while high levels of it may cause mortality. NO2 may cause methemoglobina in fish and gut and intestine cancer in human. To overcome some of these problems, one of the solutions for NH3 and NO2reduction (or removal) is the use of biological processes. Microalgae have potential use to remove the excess nutrients and other contaminants because of their high capacity nutrient uptake. Most of literature stated that green algae, Scenedesmus quadricuada could be used for NH3 removal due to suitable growth, high tolerance and low cost of culture technology. The purpose of this study was to determine NH3 and NO2 removal efficiency of green algae, S. quadricuada from fish farm wastewater effluent as well as algal biomass production.

In recent years, more emphasis has been put on water quality rather than surveying for new groundwater resources in industrialized countries. In contrary, in most developing countries groundwater quality and specifically pollution problems has not yet been taken into account as a result of finance allocation problems and scientific complication of such investigations.The most interesting discussion in hydrochemistry is the evaluation of water quality for various goals. However, more attention is paid to water resources for drinking purposes, specifically groundwater resources, due to accessibility and economical reasons, with respect to surface water. In general, these resources contain better quality as compared to surface water, but they are also subjected to chemical and biological contamination, as a result of fertilizer usage and swage intrusion into groundwater reservoirs and eventually harming public health.

Growing aquaculture activities to meet the growing global demands for fish consumption have increased the risks of reverse environmental impacts, such as water pollution and biodiversity loss. This concern has attracted great official attention in most nations. In flow-through aquaculture systems like raceways and tanks, effluents are discharged to environment with enhanced concentrations of nutrients and solids. Such effluents may have serious negative impacts on the quality of the receiving water, especially when the discharged is untreated.

The increasing trend of urbanization has highlighted the importance of city parks for providing opportunities for recreation and leisure activities and as biodiversity hotspots in urban areas. On the other hand, conservation of urban biodiversity has become one of the aims of urban managers in many cities of the world and it is even possible to find different kinds of reserves in urban areas. Higher richness of bird species can be considered as a reflection of the healthiness of the park and may satisfy visitors to a higher extent, feeling to be in a more natural environment. Therefore, attracting birds to city parks can be considered as one of the aims of urban managers. The purpose of this study is to examine the relationship of area, shape and crowdedness of city parks with their bird species richness.

Protected areas (PAs) are well known to act as sources for food, fuel, clothing, and medicines. Unfortunately, as these resources diminish outside Pas, the pressure on them becomes more intense. For this reason, landscape approaches are required to protect and restore the ecosystem services of PAs. This is especially critical due to the fact that by 2025 over 60% of the world’s “absolute” poor will live in rural areas, depending directly on the natural resources around them. There are many instances where PAs support local requirements while discouraging commercial interests of outside from rapidly depleting resources. PAs also directly contribute to increased resources - for example- in agriculture, through services such as pollination, or in fisheries through the creation of “no take” zones that allow fish stocks to recover. All over the world, PAs are established by governments, nongovernmental organizations and private entities with the aim of conserving biodiversity, and in most cases, without considering how PAs would affect the interested parties and their livelihoods

Plant communities have inherent dynamics. Environmental factors such as climate, topography and soil, can affect plants dynamics. Climate which depends on spatial and temporal scales has different effects on vegetation. In regional scale, ecosystem development and its variations in the world, are functions of climate, while smaller scale changes in each season and during the seasons of plant growth and development, were controlled by climate. Physical and chemical properties of soil cause extensive diversity and geographical distribution of vegetation. Topographic factors such as altitude, slope and size affect on the evapotranspiration of plants and soil drought. This can influence the availability of water for plants. Determination of the relationships between vegetation and environmental factors is necessary for careful management and planning programs of rangeland ecosystems, especially in arid regions. Knowledge and understanding of the realistic relationship is essential for sustainable utilization and proper management of these ecosystems. Therefore, the present study aims at identifying the plant communities and the most important environmental factors (soil, climate and topography) that influence the distribution of these communities.

There is an interest in using alternative silvicultural systems like selection and uneven aged management. Repeated entries into forest stand to remove timber increase the risk of residual stand damage. By reducing the negative impacts of harvesting on non-timber-related uses, it is possible to increase the overall level of timber production which is socially optimal forest lands. In Iran’s Caspian forests selection cutting method used for management and logging operation is generally applied by using ground based skidding system. Selection cutting is appropriate for forests composed of trees of different sizes and ages. Selection cutting does not have a visual impact on landscapes because only some of trees are removed, a factor that is much appreciated by forest users. Selection cutting improves the health of the stand and releases space for young trees to grow.

Urbanization is a complex dynamic process playing out over multiple scales of space and time. Virtually all of the world’s future population growth is predicted to take place in cities and their urban landscapes – the UN estimates a global increase from the current 2.9 billion urban residents to a staggering 5.0 billion by 2030. Most of this growth will occur in the developing countries of Africa and Asia, mainly in small and medium sized cities rather than mega-cities. A recent review of worldwide natural hazard losses during 2001 identified 700 natural disasters, resulting in 25, 000 deaths,  $36 billion in economic losses, and $11.5 billion in insured losses

A problem which urban planners are always faced with is the unequal growth and development of region. If we take a look at spatial distribution of facilities in regions we can notice that these activities have not been distributed equally. Therefore, one of the common criteria in urban and regional planning is the ranking of regions based on their share of different development indicators. On the one hand, the existing inequality between urban and rural areas and increasing in recent years, the need for more such research will reveal. In this research attempted to Evaluation and analysis of development indicators in township of Fars province by using factor and cluster analysis techniques. In this research having gone through different techniques of factor analysis every townships in Fars province gained some scores in relation to extracted factors. The result of combination index scores has shown in the table of. This study determined the most important goals of development levels, reduction and analysis of development indicators using factor analysis, identify homogeneous clusters by using cluster analysis techniques and was provide Solutions and strategy to achieve sustainable development in the township of Fars province.

How could we insert the concerns of sustainable development to the fields of architecture and urbanism? What are the characteristics of a sustainable project of architecture or urbanism? How could we define the degree of sustainability? These are the questions to which we are trying to find a response, through the method of HQEÒ. At first, we have to be aware about the nature of "relativity" of sustainability. It is accepted that sustainability is not attainable in its absolute aspect. In this point of view, the example could be utopian and unreal, where everything is perfect and ideal. Usually the degree of sustainability is defined according to a comparison with another case or a defined level of performance. To do so, we need to develop an evaluation system with criteria and indicators which allow us to have a basis of judgment for the case study.

Transportation, as a facility, has made movements easier for humans. Over time, developments have contributed to better transportation. With increasing demand for better transportation systems, which is capital intensive, research and study have to be conducted to minimize costs and maximize benefits. In the development of urban network, one of the most important and critical problems encountered is locating land uses and existing route network. In other words, the layout of urban transportation network plays a significant role in urban landuse development. Some land uses are more sensitive to transportation environmental impacts.

In many developing countries, growing trend of manufacturing mechanization, high costs of using cleaner fuels and priority of economic issues to environmental issues, have caused the environmental costs to be ignored in policy making. However, considering the environmental costs created by the development, can lead to the reduction of damages to environment.According to ability of input– output tables to describe the different relationships between economic sectors, many studies show that this can be used as an appropriate average to enter the environmental calculations into economic policies of a country.

Iran with 2500 years of ancient culture has been the witness of many changes during the history. The reason that makes this country a place for studying cultural, social and natural processes is the universal cultures which have first seen in this country. A wide range of habitats with different characteristic has created down the ages because of the cultural and religious processes, and each left its mark all over this country. The natural context of these habitats has been the victim of some changes during years, which have roots in people’s beliefs in each period. But the point which we understand by studying the context of different cultures in Iran is, despite the changes in dominions and religions along the history, Iran has a long history in sanctifying natural elements which in some points as a result of this sacredness many special species, watersheds and landscapes has been protected, and it is still valuable to natives. this landscapes are highly valuable in ecological prospects and various in physical features. They still keep their physical elements and original shape.