River toxic metal (TM) pollution is a serious challenge of present-day Iran, given that the majority of national developments are situated close to rivers. In this research, we measured and compared physicochemical quality properties, algae chlorophyll, carotenoid, and allophycocyanin contents, bioaccumulation factor (BAF), sediment quality indices, and the concentrations of Cd, As, and Pb in both sediment and algae samples across four seasons and at six reference stations along the Zayandeh-Rood River in Central Iran. The most abundant species were Spirogyra abbreviata, Spirogyra adnata, Characium acuminatum, and Navicula sp. The mean concentrations of TMs (mg/kg) were as follows: Pb(21.07) > As(5.46) > Cd(0.98) in sediment and Pb(25.99) > As(6.18) > Cd(0.85) in algae, revealing a similar pattern. The correlation coefficients between algae and sediment TMs were mostly positive with BAF > 1 which indicate the ecological implications of algae as bioaccumulators of these TMs. The lack of significant correlations between algae characteristics and the accumulation of TMs can be attributed to their threshold tolerance and the use of a multi-species analysis. Based on sediment quality indices, the river was identified as being highly polluted with Cd. This pollution can be traced back to the uneven distribution of various anthropogenic activities along the river's course, especially agricultural practices and steel manufacturing plants. As a result, there is a consistent but progressively increasing distribution and accumulation of TMs downstream. These findings emphasize the critical need for continuous monitoring of TMs in both sediment and algae to safeguard the health of the ecosystem.

鉴于大多数国家开发项目都位于河流附近，河流有毒金属（TM）污染是当今伊朗面临的严峻挑战。在这项研究中，我们测量并比较了四个季节沉积物和藻类样品中的理化质量特性、藻类叶绿素、类胡萝卜素和别藻蓝蛋白含量、生物累积因子 (BAF)、沉积物质量指数以及 Cd、As 和 Pb 浓度以及伊朗中部扎扬德-鲁德河沿岸的六个参考站。最丰富的物种是Spirogyra abbreviata、Spirogyra adnata、Characium acuminatum和Navicula sp 。沉积物中 TM 的平均浓度（mg/kg）如下：沉积物中的 Pb（21.07）> As（5.46）> Cd（0.98），藻类中的 Pb（25.99）> As（6.18）> Cd（0.85），揭示了类似的模式。藻类和沉积物 TM 之间的相关系数大多呈正相关，且 BAF > 1，这表明藻类作为这些 TM 的生物累积者的生态意义。藻类特征和 TM 积累之间缺乏显着相关性可归因于它们的阈值耐受性和多物种分析的使用。根据沉积物质量指数，该河被认定为重度镉污染。这种污染可以追溯到河流沿岸各种人类活动的不均匀分布，特别是农业活动和钢铁制造厂。因此，下游 TM 的分布和积累是一致但逐渐增加的。这些发现强调了持续监测沉积物和藻类中的 TM 以维护生态系统的健康至关重要。