Algae play an important role in all aquatic ecosystems by providing all living organisms of water bodies with preliminary nutrients and energy required. However, abnormal and excessive algal growth so-called algal bloom would be detrimental as much. Given the importance of algae in aquatic environment as well as their sensitivity to environmental changes, algal measurements are of key components of water quality monitoring programs. The algal blooms could include a variety of adverse impacts on environmental, social, cultural and economic environments. The present study is an overview on the algal growth, its mechanisms and mitigating strategies in aquatic ecosystems whereas in spite of the growing knowledge of human being of ecological, physiological, and functional conditions of eutrophication, a systematic understanding of algal blooms is still lacking.

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Background & Objective:The selection of municipal solid waste landfills is significant because it controls environmental pollution and its problems. Since site selection is a time-consuming and multifaceted process involving various socio-economic and environmental parameters, it requires expert opinion, extensive information resources, and multi-criteria methods. Therefore, this study was carried out for landfill site selection of municipal solid waste of city of Kermanshah combining SWARA technique and Copras method using GIS in 2019. Materials & Methods:In this descriptive study, the Copras method and SWARA technique were selected as multi-criterion decision-making methods (MCDM) were used. Also, the environmental and socio-economic criteria including height above sea level, geographical direction, slope, distance from the protected areas, distance from the agricultural areas, land use, distance from the road, distance from the airport, distance from railway lines, distance from transmission lines, surface and groundwater resources, distance from residential areas, distance from faults, type of vegetation and soil type were evaluated by seven environmental specialists. Results:The results of the SWARA method showed that the water resources criterion with a final weight of 0.300 is the most important criterion. Also, the type of soil and the distance from agricultural lands with a final weight of 0.202 and 0.119, respectively are the others. While, slope, distance from transmission lines and distance from fault with final weights of 0.020, 0.015 and 0.015 were the least important criteria for site selection. Besides, the results of the Copras method showed that the southwestern areas of the city of Kermanshah had better conditions for disposal of municipal solid waste due to their characteristics such as distance from residential areas and agricultural lands, suitable slope, and proper road access. Thus, the "Shah Vali" site with an approximate area of 90 ha was suggested as a landfill for municipal solid waste in city of Kermanshah for the next 20 years. Conclusion:In general, based on the results obtained, SWARA and Copras methods, due to their novelty, high flexibility, and accuracy in presenting the results, could be an excellent alternative to the other conventional weighting methods. Consequently, we can confident to their final proposed options, which have suitable characteristics of the landfill. Finally, given that landfill site selection is one of the most critical environmental issues in metropolitan areas, consider other criteria such as demographic parameters and the application of newer multi-criteria decision-making methods such as ARAS and MULTIMOORA in site selection studies are recommended.

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