Abstract
Gorganroud is one of the rivers destined to the Caspian Sea, passing through many land uses, including the agriculture, forest and the urban areas. Regarding to the MPs (microplastics) pollution of the Caspian Sea, assessment of rivers as a source of driven MPs could be helpful for sustainable management of aquatic environments. The present study determined Gorganroud MPs pollution through sampling of eight selected stations along the river. The abundance and distribution of MPs in sediments and some fishes along the was evaluated, Characteristics of microplastics with attached elements were analysed and confirmed with Microscope (stereo and SEM), FTIR (ATR and Micro Raman. The average abundance of MPs along the River sediments ranged from 220±66 to 2460±444 items/Kg. The most abundant of MPs reported from stations situated in urban areas, which shows MPs in the Gorganroud River originates from cities wastewater effluents. Over 80% of these MPs were less than 2 mm. What's more, the majority shapes of MPs were fiber, followed by fragment and film. Black and gray were the dominant color among sediment MPs. whereas the most common polymer types of these MPs in sediments were polypropylene (39%), polyethylene (26%), polyamide (16%), polystyrene (14%) and polyester (5%); polymers in fish consisted of polypropylene (37%), polystyrene (29%), polyethylene (25%) and polyester (9%). Regard to the fish, samples consisted of Carassius gibelio, Paracobitis hicanica, Gambusia holbrooki, Neogobius melanostomus, Capoeta capoeta, Alburnoides eichwaldii. The most abundant MPs detected in Neogobius melanostomus (0.72 n/g) caught mainly from stations situated along areas of agricultural fields. The same as sediment samples, prevalence shapes within digestive tract identified as fibers, followed by fragments and films. Although MPs size ranged from 0.1- 3 mm, dominant MPs size was less than 1mm. Moreover, Black was the frequent color detected within digestive tract. This survey demonstrated that the Gorganroud River is a sinking MPs pathway to the Caspian Sea ecosystem.
Keywords: Microplastic, Gorganroud, Fish, Sediment, Pollution