Microplastics and associtated polycycylic aromatic hydrocarbons and risk assessment for surface water and sediment in Konya closed basin

In the thesis study, the number, morphological characteristics, color and polymer type of microplastics were determined in water and sediment samples taken from surface waters that the General Directorate of State Hydraulic Works monitor the quality of surface waters in the Konya Closed Basin. The concentrations of 16 polycyclic aromatic hydrocarbon (PAH) compounds associated to microplastics in water and sediment samples were determined. Sources of PAH pollution in water sources have been identified. A microplastic risk assessment was carried out for the sampled water sources, water collection areas and Konya Closed Basin. Surface water resources are of good (class II) and medium (class III) quality water in terms of physico-chemical parameters. The number of microplastics was detected in the range of 1138-23444 MP/m3 in 37 surface water and 150-3510 MP/kg in 24 sediment. It was observed that fiber (51%) and fragment (29%) microplastic morphology were dominant in the water resources in the basin, followed by film (15%), pellet (12%) and foam (4%) shaped microplastics, respectively. It was observed that the transparent color (69%) was dominant in the detected microplastics, followed by white, grey, blue, black and other colored microplastics. It was determined that the detected microplastics contained 34% polyethylene (PE), 25% polypropylene (PP), 24% cellophane (CP), 12% polydiene (PD), and 5% polycarbonate (PC) polymer. The morphological characterization, color and polymer types of microplastics in sediment are similar to those detected in water. While taking samples, it was observed that plastic materials used in agricultural areas and plastic waste used in daily life originating from residential areas were inappropriately disposed of around water resources. Fiber and fragment microplastics, which are predominantly detected in microplastic morphology, are thought to originate from urban waste discharges and textile wastes from domestic wastewater, vehicle tires from traffic, and plastic wastes left inappropriately in the environment. It is thought that the predominantly transparent and white colors detected in surface waters may be due to greenhouse and mulching practices due to intensive agricultural activities in the Konya Closed Basin. As a result of the risk assessment for the microplastic amounts and polymer types detected in surface waters and sediments; According to the Contamination Factor (CF) values, 35% of the surface waters are moderate, 27% are significant and 38% are very high, 25% of the sediments are moderate, 21% are significant and 54% are very high exposed to microplastic pollution. In terms of Pollution Load Index (PLI), it was determined that all sample areas and the Konya Closed Basin were contaminated with microplastics (PLI > 1) for both surface waters and sediments. It was evaluated as medium risk (10 < H < 100) in the Polymeric Risk Assessment for Konya Closed Basin surface water and sediments. In the evaluation of the Konya Closed Basin Pollution Risk Index, it was determined that it was low risk for surface waters (PRI < 150) and significantly risk for sediments (300 < PRI < 600). The Pollution Load Index in surface waters, especially in Niğde and Ereğli regions, was determined to be higher than other regions. In sediments, the pollution load index of the Hadim-Taşkent region was determined to be higher than other regions. Measures to prevent microplastic pollution should be applied to these regions first. The total 16-PAH concentration associated with microplastics was detected in the range of 393- 24755 ng/g in surface waters and in the range of 37.3-18323 ng/g in sediments. Phenanthrene was dominantly detected in surface waters, and phenanthrene, anthracene and fluorene compounds were dominantly detected in sediments. The sources of PAH compounds associated with microplastics in surface waters in the Konya Closed Basin were determined as domestic fuel use, traffic-related diesel engines, oil pollution and factory emissions. It has been determined that the pollution in the Konya Closed Basin is of petrogenic origin. Today, plastics used in every field have become an important environmental pollutant with increasing usage amounts. Especially when the current situation regarding microplastic pollution is evaluated, urgent measures need to be taken in the Konya Closed Basin water resources. First of all, the use of single-use plastic products should be restricted and plastic waste should be recycled and disposed of with an effective waste management system. Discharge limit values for microplastics should be determined in regulations for wastewater, which is an important source of microplastics. The public should be informed about the extent and possible effects of plastic pollution. In addition, it is necessary to conduct studies on the fate of microplastics in water resources and micropollutants carried by microplastics, and their risks to human and environmental health.