Ecological Risk Assessment of Microplastics in Luoma Lake and its Connecting Rivers

Microplastics (MPs), an emerging environmental pollutant, have been found in inland waters with increasing frequency, directly affecting human health and ecological security. However, the abundance and contamination risks of MPs in inland waters remain insufficiently understood. This study systematically investigated the occurrence of MPs in the surface layer of Luoma Lake and its inflow/outflow rivers by conducting field sampling. It estimated the environmental risks of MPs using a combination of the pollution load index (PLI), the polymer hazard index (PHI), and the potential ecological risk index (PERI). MPs were found in all samples, ranging from 3.2 to 12.2 particles/L (average 7.1 particles/L). A total of 10 color types were detected, of which white (23.4%) and transparent (21.1%) were the main color types. The most common dimension was below 100 μm (68.5%), while the predominant shapes were debris (37.1%) and granular (35.3%). The prevalent polymers were terephthalate polyethylene (PET, 34.1%) and polyethylene (PE, 27.5%). Based on PLI, PHI and PERI analysis, the Luoma lake and its inflow/outflow rivers exhibited a low MPs pollution load (level I), a middle polymer hazard (level II), and a low potential ecological risk level (level I), respectively. The findings improve understanding of the ecological risks of MPs pollution in Luoma lake, providing basic data and technique reference for the MPs pollution control and the protection of drinking-water sources.