PROGRAMME

The presence of microplastics (MPs) in water is an indicator of the increase of human impacts on the Earth. In this study, water of the channels and ponds that conduct a mix of surface water and treated wastewater in two cities of Saudi Arabia were assessed to ascertain the influence of the population on abundance and characteristics of MPs (>20 µm in size). The selected cities were Riyadh with a population of 5,188 million inhabitants and al-Jubail with a population of only 0.77. MPs. The MPs were isolated using showed an average of 3.2 items/L in Riyadh and 0.2 items/L in Al-Jubail showing a clear relationship between presence of microplastics and density of population. Fibers were dominant in all sites (60 %); their size was mainly distributed between 80 and 250 µm (60 %), and white (40 %) red (25 %) and blue (20 %) were the dominant colors. Infrared spectral analysis revealed that most of the selected particles were identified as MPs of polypropylene and polyethylene (48.3%). The risk assessment performed using two approaches showed higher risk for Riyadh whether the MPs could be acutely hazard for aquatic biota. Our study provides new insides for establishing the impact of MPs in channels and surface water increasingly affected by the re-use of wastewater treatment plants. Acknowledgement - The authors thank the financial support from the project number (RSP-2020/11) King Saud University, Riyadh, Saudi Arabia.