Sources of polychlorinated dibenzo-p-dioxins and -furans to sediment in the Newtown Creek Superfund Site

Polychlorinated dibenzo-p-dioxins and -furans (PCDD/Fs) are contaminants of concern in the New York/New Jersey Harbor and in the organisms of the Newtown Creek Superfund site, which lies within the harbor. Because PCDD/Fs are never intentionally produced, identifying their sources can be challenging. In this work, sources of PCDD/Fs to the sediment of Newtown Creek were investigated using Positive Matrix Factorization (PMF) to analyze two data sets containing data on concentrations of (1) PCDD/Fs and (2) PCDD/Fs plus polychlorinated biphenyls (PCBs). The PCDD/F data set generated eight factors, but they were not particularly helpful in identifying PCDD/F sources. The combined PCDD/F plus PCB data set generated eleven factors, many of which represented Aroclors. Based on its spatial distribution, the primary source of PCDD/F-related Toxic Equivalency Quotient (TEQ) in the sediment (accounting for 53 % of total TEQ) may be related to a facility that performed smelting and refining of metals (primarily copper). Aroclors appear to be responsible for about 20 % of the total TEQ. This analysis revealed two additional secondary sources of PCDD/Fs to Newtown Creek sediment: the East River (3 % of TEQ) and Combined Sewer Outfalls (CSOs; 0.5 % of TEQ). The East River was responsible for most of the mass of 2,3,7,8-tetrachloro dibenzo-p-dioxin (TCDD) in the sediment, presumably because it transports TCDD-laden sediment from the Passaic River into Newtown Creek. CSOs were proportionately more important in surface sediments. Adding PCBs to the data matrix appears to increase ability of the PMF analysis to identify both primary (Aroclors) and secondary (CSOs, East River) PCDD/F sources, but it is unclear whether it may overstate the fraction of PCDD/Fs arising from Aroclors.