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 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.

在2019年卡伦河洪水之后，与2015年洪水前研究相比，该研究旨在评估对沉积物中理化特性和潜在毒性元素（PTEs）浓度的影响。从穿过阿瓦士市的河床收集了表面和岩心样品，以进行分析和评估。用标准方法测定了沉积物的理化性质和样品中PTE（Mn，Fe，Cr，Ni，As，Zn，Pb和Cu）的浓度。通过计算污染因子和污染程度来评估沉积物中的PTE污染。潜在的生态风险指数（RI）用于评估沉积物中PTE的污染程度和生态影响。比较结果表明，洪水降低了沉积物中PTE和有机碳的浓度。与洪水前的样品相比，洪水还降低了淤泥和粘土含量，并增加了酸度和沙子含量。洪灾后生态风险评估表明，与洪灾前相比，沉积物的风险仍然较低。与洪水前相比，洪水后沉积物中PTE的浓度降低可能是由于长期暴露于洪水前沉积物中的污染物。看来粘土颗粒和有机碳（作为污染物的重要吸附剂）数量的减少已导致沉积物中污染物的减少。洪水后沉积物中PTE的统计分析表明，金属的主要来源是地质成因。