Assessment of the impact of 2019 Karun River flood on river sediment in Ahvaz city area, Iran
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Assessment of the impact of 2019 Karun River flood on river sediment in Ahvaz city area, Iran Fatemeh Rastmanesh Alireza Zarasvandi
&
Tahereh Barati-haghighi &
Received: 25 January 2020 / Accepted: 14 September 2020 # Springer Nature Switzerland AG 2020
Abstract Following the 2019 Karun River’s flood, this study was conducted to evaluate the impact on the physicochemical characteristics and potentially toxic elements (PTEs) concentrations in the sediments as compared to 2015 pre-flood study. Surficial and core samples were collected from the river bed stretching through Ahvaz city for analysis and evaluation. The physicochemical properties of the sediments and the concentrations of PTEs (Mn, Fe, Cr, Ni, As, Zn, Pb, and Cu) in samples were determined by standard methodology. The PTEs contamination in sediments was assessed by calculating the contamination factor and the contamination degree. The potential ecological risk index (RI) was used to assess the contamination degree and ecological effects of PTEs in sediments. The comparative results showed that the flood reduced the concentration of PTEs and organic carbon in the sediments. The flood also decreased the silt and clay content and increased the acidity and sand content compared to pre-flood samples. The post-flood ecological risk assessment revealed that the sediments remained as low risk as compared to pre-flood state. Reduction of post flood PTEs concentration in the sediments as compared to pre-flood concentrations is probably due to long-term exposure to pollutants in the pre-flood sediments. It appears the reduction in the amount of clay particles and F. Rastmanesh (*) : T. Barati-haghighi : A. Zarasvandi Department of Geology, Faculty of Earth Sciences, Shahid Chamran University of Ahvaz, Ahvaz, Iran e-mail: [email protected] e-mail: [email protected]
organic carbon (as important adsorbents for pollutants) has resulted in reduction of pollutants in the sediments. Statistical analysis of PTEs in the post-flood sediments showed that the major source of metals is geogenic. It seems that despite being destructive for the inhabitants, the flood, has reduced the amount of pollutants and the ecological risk, in the study area, at least for a while. Keywords Karun River . Flood . Sediment . PTEs . Ecological risk . Iran
Introduction The flooding danger threatens people in many countries. Throughout the world, the flood has been recognized as one of the most severe disasters among the 15 types of natural disasters (Zhou et al. 2002). Floods can have direct mechanical effects and affect soil properties by sediment transport. This can create problems for agriculture and human health (Weber et al. 1998). Floods can damage soil structure by separating aggregates (Eulenstein and Helming 1998). As a result, excess water replaces oxygen by entering the soil and occupying the empty spaces, thereby reducing soil ventilation. The consequence is the incomplete decomposition of organic matter and the production of various gases such as greenhouse gases, a de
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