Environ Monit Assess. 2026 Aug 6;198(9):920. doi: 10.1007/s10661-026-15752-w.
ABSTRACT
This study integrates longitudinal groundwater monitoring, spatiotemporal plume modeling, and deterministic health risk assessments to evaluate petroleum-derived contamination at an urban fuel station on the European side of Istanbul, Turkey. Over a 20-month monitoring period encompassing ten sampling events, the spatiotemporal distribution of benzene, toluene, ethylbenzene, xylenes (BTEX), methyl tert-butyl ether (MTBE), and total petroleum hydrocarbons (TPH) was analyzed using the Groundwater Spatiotemporal Data Analysis Tool (GWSDAT). Results revealed significant subsurface migration governed by the local hydraulic gradient, with maximum concentrations peaking at 79,000 µg/L for MTBE at the facility boundary and 5100 µg/L for benzene. MTBE acted as a high-mobility tracer, forming the leading edge of the dissolved-phase plume and demonstrating active off-site migration vectors into the adjacent unconfined aquifer. To quantify the resulting environmental liabilities, Tier 3 human health risk modeling was conducted using the Risk-Integrated Software for Cleanups (version 5.0) framework for adult and child receptors across ingestion, dermal, and inhalation pathways. The assessment indicated a severe, unacceptable non-carcinogenic threat to pediatric populations, with a cumulative hazard index (HI) reaching 13, driven primarily by the inhalation of indoor vapors volatilizing from the subsurface plume. For adults, the cumulative HI was 3.9, while the excess lifetime cancer risk (ELCR) exceeded the standard regulatory safety threshold of 1 × 10-6 due to persistent benzene mass flux. Probabilistic sensitivity analysis identified exposure duration and the soil-to-indoor air attenuation factor as the most critical parameter uncertainties. These concrete toxicological metrics demonstrate that natural attenuation alone is insufficient. Consequently, an adaptive remediation framework, utilizing in situ chemical oxidation (ISCO) for the mobile MTBE leading edge and soil vapor extraction (SVE) for the volatile BTEX source, is required, providing quantitative justification for municipal authorities to enforce strict land-use setbacks and mandatory indoor vapor screening.
PMID:42560596 | DOI:10.1007/s10661-026-15752-w
