فصلنامه محیط شناسی
سال چهل و نهم شماره 2 (پیاپی 106، تابستان 1402)

This study was conducted to evaluate the consequences of land use changes on the values of ecosystem services in urban areas of the west of Tehran province. For this purpose, first, the land use/cover types of the region in 1985, 2000 and 2015 were classified using the maximum likelihood method, and their changes over time were examined. Then, different types of existing ecosystem services were identified using the theoretical approach presented by Costanza et al. (1997), and their economic value was calculated. Finally, the relationship between factors affecting land use changes and ecosystem service values was analyzed using multiple regression. The results show that, following the reduction of rangelands and agricultural lands, the value of ecosystem services has decreased by 51.2%. Based on the results of the regression analysis, the nine following factors affecting socio-economic development have the greatest impact on reducing the value of ecosystem services in the region, respectively: the increase in the number of roads, number of employees, population, public vehicles, non-agricultural income, value of industrial assets, number of immigrants, size of agricultural plots, and GDP. Therefore, spatial planning measures, such as spatial rules and policies, should be taken in this region to prohibit the expansion of constructed lands in the area of green and natural lands.

Climate change and its consequences for residents in various regions have led to environmental migration, which has become in the center of attention of researchers and policymakers. Using mixed method approach, this paper aims to understand the relationship between drought and internal migration. Accordingly, in the quantitative part, by estimating the 30-year drought level for 110 counties using the SPI index and out-migration rates of the selected counties, the relation between these two variables was examined. The results show that drought in dry regions has a positive relationship with migration in these regions. However, no correlation was found in other areas of the country with different climates. In order to better understand the issue, two districts of Negin Kavir in Kerman Province and Tasooj in Fars Province, which are regions with very dry climates, respectively, have been investigated. A sample of residents of each region were in-depth interviewed about the effects of drought on their lives. The results indicate that drought affects the residents of these regions in two ways: risking their livelihoods and risking people’s health. In the occurrence of continuous droughts, migration is considered as a last solution to the problem, and prior to that the residents of such regions try to confront this problem by adjusting their lives with these new conditions. However, in comparison with residents of more developed regions, residents of less-developed regions have a less opportunity to adapt with the new condition. Accordingly, adaptation strategies in these regions have failed, and people were forced to migrate.  Therefore, the impact of drought on migration depends upon the climate situation as well as regional economic contexts and development level.

Sustainable development through minimizing the negative externalities on the environment is one of the important topics of economic research in recent decades. The emission of carbon dioxide resulting from the combustion of fossil fuels in diverse sectors of the economy, which include industries, power stations, transportation, and even the household sector, as one of the externalities of human activities today, is known to be the cause of environmental destruction. This paper analyzes elements which affect the emission of carbon dioxide in MENA region countries, during 2004 to 2020 by expanding the spatial Green Solow model and using the dynamic spatial panel model (DSM). The results of the estimates imply that population growth, urbanization growth, the share of industry in the GDP and the degree of trade openness have a positive and significant effect on carbon dioxide emissions. However, no significant relationship was discovered between the two variables of democracy and physical investment with carbon dioxide emissions in the goal nation. On the other hand, the spatial correlation among sections was confirmed. In addition, the convergence of the factors affecting carbon dioxide emissions was confirmed in the investigation period, which means that nations have tried to reduce carbon dioxide emissions in the duration.

An ecosystem approach to wetland management is a strategy for integrated management of water, land, and livelihood resources that promotes conservation and sustainable use in a balanced manner. For implementing this approach, commercial mechanisms, and incentives, especially the "Payment for Ecosystem Services Mechanism" (PES) that can ensure the internalization of environmental externalities, are increasingly proposed as a promising mechanism. This study aims to investigate the acceptance rate of this mechanism among the communities affecting Anzali wetlands as a case study. The required legal rules were also identified and surveyed among the statistical population. This study is a "descriptive-correlation" study, and the sample members were selected by purposive sampling. These sample members were selected from among three groups of Anzali wetland communities. There were 21, 750, and 972 people in the community of governors, positive and negative beneficiaries, respectively, and 21, 254, and 275 of them responded to the questionnaire. The statistical analysis of the results showed that, with a probability of 95% confidence, the payment for ecosystem services mechanism through appropriate legal frameworks could be useful and effective for implementing the ecosystem approach. Also, with a probability of 95% confidence, the acceptability of "proposed legal rules" was not the same among the target communities, and based on the results, the average index of "proposed legal rules" in negative beneficiaries is higher than positive beneficiaries, and in positive beneficiaries is more than governors.

Activated sludge process is one of the most widely used methods of urban wastewater treatment. The purpose of this study is to use nanobubbles to supply oxygen to the aeration reactor in the activated sludge process and to evaluate its performance in terms of increasing the efficiency of wastewater treatment, reducing energy consumption, reducing the amount of excess sludge and its impact on environmental factors. The results showed that the use of nano-bubble compared to the use of macro-sized bubbles increased the concentration of dissolved oxygen in the aeration reactor up to 3 mg/liter, 18% reduction in energy consumption, 10% reduction in the initial investment in the construction of the wastewater treatment plant. 15% reduction in operating costs of the sewage treatment plant. Increasing the efficiency of removing organic pollutants and reducing the hydraulic retention time in the aeration system, reducing the size of the treatment plant by 10% due to the increase in the efficiency of removing organic substances, and as a result, reducing the hydraulic time and reducing the same amount of land for the construction of the aeration reactor and facilities for the production and distribution of air in the aeration reactor. The presented model, which is obtained by using nano-bubbles in the aeration process of bioreactors, is very effective as a new and innovative technology in preserving, cleaning, and sustaining the environment.

Due to the high volume of their daily production, the optimal management of food waste is of special importance in all countries, especially from the environmental and health point of views. Because of its chemical and structural nature, this type of waste is easily decomposed and has a high potential to produce leachate and emit greenhouse gases, soil pollution, etc. in case of improper management. Due to the importance of the subject, the present study was carried out with the general aim of analyzing the content of the upstream documents at three national, regional and local levels in order to deduce the goals of the sustainable waste management system in Tehran. For this purpose, 15 upstream documents (5 national documents, 5 regional documents and 5 local documents) were selected as targeted and available samples for study. The selected documents were analyzed using the content analysis method of Gal et al. and the relevant concepts were extracted and coded. According to the results, the goals of sustainable food waste management in Tehran are presented in the form of five institutional (integration and inclusion of key elements of the urban waste management system), technical and infrastructural (optimizing existing processes in the use of technologies), environmental (minimizing adverse health and environmental effects), economic (financial sustainability) and cultural-social (attracting the maximum participation of citizens) categories. Finally, suggestions have been made to achieve each of the goals.

Considering the increasing growth of environmental crimes, it is significant to identify the effective factors in preventing crimes in this area. Based on this, the aim of this study is to investigate the factors affecting the prevention of environmental crimes in Herat city, Afghanistan. The statistical population of this research comprises the students of the Faculty of Agriculture of the State University of Herat city, from which 277 people were selected as the final volume based on random sampling using Cochran's formula. The tool for collecting information is a researcher-made questionnaire with emphasis on five political, economic, cultural, social, and legal variables, whose formal, content, and structural validity and reliability were confirmed. To investigate the relationship between the variables and their effect on preservation of the environment of Herat city, the one sample t-test was used, and Friedman's test was carried out to rank the variables. The findings of the one sample t- test showed that among the political, economic, cultural, social, and legal variables, only political, legal, and cultural factors have a direct and meaningful relationship with the prevention of environmental crimes. However, the findings of Friedman's test proved that among the five variables, the cultural factor ranks first and the economic variable ranks last.