Microplastic pollution is an emerging threat to marine environments with potential environmental, social, economic, and health consequences and has become a major global environmental issue. The objective of the present study was to evaluate microplastic contamination in the ecosystem of the Qara Su River in Ardabil, Iran. Fifteen sampling sites along the Qara Su River in the Ardabil urban area were selected to collect sediment samples. The abundance and morphological characteristics of microplastics were determined by counting using a digital stereomicroscope. Micro-Fourier transform-infrared spectroscopy (μ-FTIR) analysis was used to identify polymer type of the microplastics. In this study, the frequency and distribution of microplastics (< 5 mm) in the sediment of Qara Su River were investigated as one of the sources containing microplastics. Sediment samples were collected from five different sites (Karkarq, Sar band, Anzab Sulfa, Dolat abad, and Samian) from September to March 2020. For microplastic examination in sediment, the amount (approximately 1000 g of fresh sediment from each site) was sampled from 15 sites. Fiber microplastics (53%) and fragments (33%) microplastics were predominant. It has shown the abundance and heterogeneity of space. In this study, the highest amount of microplastics detected in sediment samples was related to the size of less than 5000 µm (92%). The frequency of microplastics below 5000 µm in sediment was attributed to the low capacity of existing processes in Ardabil wastewater treatment plant. The abundance of microplastics shows significant differences between sampling sites. The Qara Su River along the city of Ardabil, like many other rivers, is contaminated with microplastics. This study was the first study conducted for evaluation of the sediment environment in terms of the microplastic pollution of Qara Su River in Ardabil. Considering the amount of microplastics in sediments, further research is required to estimate the amount of microplastics released by Ardabil wastewater treatment plants and industrial town wastewater, and other possible sources of emission and to evaluate their contribution to microplastic pollution in water, sediment, and soil. This study provided a framework for future studies of microplastics pollution in the sediment of urban areas around the Qara Su River in Iran.

微塑料污染是对海洋环境的一种新兴威胁，具有潜在的环境、社会、经济和健康后果，已成为一个重大的全球环境问题。本研究的目的是评估伊朗阿尔达比勒 Qara Su 河生态系统中的微塑料污染。选择了 Ardabil 市区 Qara Su 河沿岸的 15 个采样点采集沉积物样品。使用数字立体显微镜通过计数确定微塑料的丰度和形态特征。微傅里叶变换红外光谱 ( μ-FTIR)分析用于鉴定微塑料的聚合物类型。在这项研究中，Qara Su 河沉积物中微塑料（< 5 mm）的频率和分布作为含有微塑料的来源之一进行了调查。从 2020 年 9 月至 2020 年 3 月，从五个不同地点（Karkarq、Sar band、Anzab Sulfa、Dolat abad 和 Samian）采集了沉积物样本。对于沉积物中的微塑料检查，取样量（每个地点大约 1000 克新鲜沉积物）来自 15 个站点。纤维微塑料 (53%) 和碎片 (33%) 微塑料占主导地位。它显示了空间的丰富性和异质性。在这项研究中，沉积物样品中检测到的最高微塑料量与小于 5000 µm (92%) 的尺寸有关。沉积物中低于 5000 µm 的微塑料的频率归因于 Ardabil 废水处理厂现有工艺的低容量。微塑料的丰度表明采样点之间存在显着差异。与许多其他河流一样，阿尔达比勒市沿岸的 Qara Su 河也被微塑料污染。这项研究是第一项根据阿尔达比勒 Qara Su 河的微塑料污染评估沉积物环境的研究。考虑到沉积物中微塑料的数量，需要进一步研究以估计 Ardabil 废水处理厂和工业城镇废水以及其他可能的排放源释放的微塑料数量，并评估它们对水、沉积物和土壤中微塑料污染的贡献.