Distribution, risk assessment, and source identification of metal(loid)s in sediments on a New York-New Jersey Harbor...

This study investigates the sources, distribution, and ecological and human health risks of metal(loid)s in sediments from the lower 8.3 miles of the Lower Passaic River (LPR), a Superfund site within the New York-New Jersey Harbor. Analysis of sediment samples revealed elevated concentrations of As, Cd, Cr, Cu, Mn, Pb and Zn, indicating localized enrichment across reaches. Ecological risk indices (i.e., CF, I_geo, EF, PERI, and PLI) classified sediments as severely contaminated, particularly with Cd and Pb, with a mean potential ecological risk index (PERI) value of 801, far above the threshold for serious risk. Sediment quality guideline indices suggested moderate to high toxicity potential. Probabilistic health risk assessment of sediment-associated metal(loid)s showed that ingestion was the dominant exposure pathway, followed by dermal contact, while inhalation contributed minimally. Pb was the main contributor to non-carcinogenic risk, with the total hazard index (HI = 1.22) exceeding the acceptable threshold, whereas other metal(loid)s showed negligible individual risks. Carcinogenic risk was primarily driven by Ni and Cr, with a cumulative deterministic total lifetime cancer risk (TLCR) of 3.38 × 10^-4, indicating moderate concern, although these estimates are conservative given the presence of unmeasured carcinogenic species of Ni/Cr/As. In contrast, probabilistic Monte Carlo estimates yielded mean lifetime cancer risk (LTCR) values within the acceptable range (1 × 10^-6-1 × 10^-4). Monte Carlo simulation and sensitivity analysis identified sediment concentration (C), exposure frequency (ExF), exposure duration (ED), and ingestion rate (IngR) as key factors influencing risk variability, while body weight (BW) and average time (AT) reduced risk estimates. Principal component analysis (PCA) revealed mixed geogenic and anthropogenic controls, including natural background (PC1, 71%), industrial/legacy inputs (PC2, 11%), and urban-related enrichment (PC3, 8%). These findings emphasize the necessity of continued remediation efforts, including sediment dredging, to protect ecosystem health.