Abstract
Microplastics (MPs) are persistent and ubiquitous pollutants in aquatic systems and now become a great concern for human health and ecosystem habitats. However, very limited research has addressed microplastic pollution in rivers and groundwater systems in Iraq and the Kurdistan region. This study investigates the abundance, sources, and characteristics of microplastics in surface water, groundwater, sediment and dust across the Alana River basin, northeast of Erbil city. Field investigations were combined with physicochemical, biological, and environmental risk assessments. All samples were collected during the dry and wet seasons, and analysed using standard filtration, microscopic identification, and micro-Raman spectrometer for polymer characterisation.
Results of this study revealed that the surface water and groundwater quality of Alana was rated as good to excellent for consumption, and nearly all samples were found suitable for irrigation. Nevertheless, microbiological indicators revealed bacterial contamination in both resources, mostly due to sewage infiltration from municipal, agriculture, household, or industrial sources. Microplastic abundance varied seasonally. During the wet season, concentrations in surface water were significantly higher (mean (M) = 5541.3 MPs/m³) compared to the dry season (M = 361 MPs/m³). Groundwater contained a mean of 640 MPs/m³ during the wet season and 160 MPs/m³ during the dry season. Furthermore, in river sediment, the mean concentration during the wet season was 1951.4 MPs/kg and 733 MPs/kg during the dry season. The highest values were reported in the atmosphere, with a mean of 58,868.3 MPs/m²/day in the wet season and 18,900.6 MPs/m²/day in the dry season. Results of MP flux in the Alana based on MP abundance show that during the wet season it was higher than in the dry season, due to increasing human activity. Fiber and fragment forms were the dominant microplastic forms in the studied region with the predominant sizes ranging from 500–1000 µm to 1000–5000 µm across all environments. Raman spectrometer identified twelve polymer types, including toxic polymers such as PVC, PS, and PUR. Risk assessment (PERI index) classified the area as extremely high risk. As well, the grain size and hydraulic conductivity related to retaining MP proved that finer sediment sizes with lower conductivity indicate greater MP accumulation in Alana areas. The results encourage and guide decision-making and monitoring related to mitigation strategies and drinking water treatment.
