Application of low-density polyethylene with advanced passive sampling device for measuring freely dissolved...

Tributyltin (TBT) has been widely used as an antifouling agent for ship hulls but has been globally regulated since the early 2000s due to its endocrine-disrupting effects, such as inducing imposex in aquatic organisms. Despite these regulations, the extensive use of TBT has led to continuous detection in coastal environments. To accurately assess its impact on aquatic organisms, it is essential to measure the freely dissolved concentration (C_free), which represents the bioavailable fraction of the total concentration (C_total) in seawater. Although passive sampling methods based on equilibrium partitioning require the polymer-water partition coefficient (K_pw) to calculate C_free, no prior studies have determined K_pw for TBT using low-density polyethylene (LDPE). In this study, experimental conditions for LDPE were optimized, and the log K_pw of TBT between LDPE and water was determined to be 3.8 within 24 h, based on time-series experiments. The log K_pw of TBT is similar to its octanol-water partition coefficient (log K_ow = 3.9). Using the obtained K_pw, the C_free of TBT in Korean coastal waters was measured with a high-speed rotation-type passive sampling device (HSR-PSD) combined with LDPE, ranged from 0.043 to 1.5 ng Sn/L. Estimated tissue concentrations (C_bio-est) ranged from 0.022 to 150 μg Sn/kg (wet weight) for gastropod, bivalve, and fish, which inhabiting in Korean coastal waters. This study demonstrates the feasibility of using LDPE-based passive sampling methods for short-term monitoring of freely dissolved TBT and as an alternative to biomonitoring with benthic organisms.