Assessment of Environmental Impacts of Salt Extraction from Urmia Lake and heavy metal presence in sediments of lake

Abstract

Introduction Urmia lake, the second largest Salt Lake in the world and the largest inland lake in Iran, is one the most important natural resources in the world with considerable values in terms of aesthetics, economic, recreational, ecological and scientific studies. Inasmuch as, launch and implementation of any economic activity without taking into account the environmental aspects can cause serious damages to the environment, EIA is necessary as a formal process for identifying the likely effects of projects on the environment and on human and to considering the significant environmental sensitivities. In recent years trend of Lake Urmia dryness in northwestern corner of Iran has been led to a great tendency especially by private sector to exploit salt from different parts of the bed sediments. This study was aimed to evaluate the environmental impacts of salt harvesting from the Urmia Lake and investigation the status of heavy metals contamination in saline and salt sediments of lake. Materials and Methods In this study, environmental impacts of the large scale salt harvesting activities were assessed by application of the modified model to the Folchi method of EIA. The baseline environmental conditions were established by field inspections. After data collection and identifying the impacting factors, a 14×12 matrix formed with correlating each impacting factor and each environmental component. Finally, the magnitude of variations caused by each one of these factors was defined and weighted sum of all impacting factors was calculated. Ten study sites were selected and sampled to assess the state of heavy metals contamination in bed sediments. Besides, quality of the lake water in the limited number of water samples from the middle sections of the lake was evaluated. Result and discussion According to the results, the most significant impacts of salt harvesting from the Urmia Lake were on three environmental components, namely “land use”, “topography of the lake bed” and “hydrology and lake water quality”. The other potential impacts are identified as effect on ecology, air quality, noise pollution and human health and safety. The mean concentrations of As, Cd, Cr, Hg, Pb, Ni and Zn in salt and sediment samples were 15.19±8.8, 0.05±0.047, 15±8.2, 0.54±0.3, 11.9±6.28, 15.4±9.56 and 22.3±13.66 mg/kg, respectively. So, dispersion of salt particles from storage salt piles may affect local people's health. Conclusion In current conditions due to significant environmental impacts, salt harvesting from Urmia Lake without technical and environmental considerations is not recommended. Also, it is mandatory to design an environmental management plan before commencing any salt mining in the region and appropriate mitigation measures should be included where necessary.