Legacy and alternative plasticizers in sediments from a highly industrialized lake in Korea: Spatial distribution, source identification, and long-term trends (2008-2024).

Following global and domestic regulations on legacy plasticizers (LPs), such as di(2-ethylhexyl) phthalate (DEHP), the environmental emergence of alternative plasticizers (APs) has become a critical concern. This study investigated the spatial distribution, source, long-term trends (2008-2024), and ecological risks of 15 LPs and 20 APs in sediments from a highly industrialized artificial lake in Korea (n = 40). LPs and APs co-occurred in sediments, with the highest concentrations found in creek sediments adjacent to industrial complexes. DEHP and di(2-ethylhexyl) terephthalate (DEHTP) were the dominant LP and AP, respectively. The novel substitute di(2-ethylhexyl) cyclohexane-1,4-dicarboxylate (Eco-DEHCH) was detected in 73% of samples, indicating its widespread environmental entry. Statistical analysis revealed distinct plasticizer profiles governed by legacy and high-tech industrial activities. Temporal trend analysis showed a marked industrial transition: DEHP concentrations declined gradually, whereas APs, particularly DEHTP, di(2-ethylhexyl) adipate (DEHA), and trioctyl trimellitate (TOTM), increased over time, along with their replacement ratios relative to DEHP. In particular, the DEHTP/DEHP ratio reached 5.17 ± 4.58 in 2024, indicating predominant DEHTP substitution in the study area. Ecological risk assessment indicated that DEHP remained the major risk driver, with 15% and 5% of samples classified as high risk for algae and fish, respectively. These findings highlight the need to consider the transition from LPs to APs in sediment monitoring and ecotoxicological evaluation.