The second source of 2,3,7,8-tetrachlorodibenzo-p-dioxin in Lower Passaic River, NJ, USA sediments

Evidence supports the presence of a second major source of 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) to the Lower Passaic River (LPR) at river mile (RM) 12 to 12.5, identified as the former Givaudan facility in Clifton, New Jersey, United States. Using sediment chemistry and high-resolution dated cores, Garvey et al. (2011) identified an anomalous dichlorodiphenyltrichloroethane (DDT) + dichlorodiphenyldichloroethylene (DDE) to 2,3,7,8-TCDD ratio near Givaudan that suggests an upstream source of 2,3,7,8-TCDD. This study integrates these same data with (a) chemical production at Givaudan and the former Diamond Alkali chemical plant in Newark, New Jersey located at RM 3.5, (b) wastewater infrastructure and combined sewer overflow bypass events, (c) river flow and hydrodynamic models of upstream transport, (d) and estimated 2,3,7,8-TCDD discharged to the LPR. The increase in 2,3,7,8-TCDD and the anomalous DDT + DDE to 2,3,7,8-TCDD ratio observed in late 1950s to early 1960s sediments between RM 10 and 12 coincides with increasing 2,4,5-trichlorophenol (2,4,5-TCP) usage (source of 2,3,7,8-TCDD) at both facilities, but the chemical signatures at RM 10 through 12 do not match Diamond. River flows prior to the drought in the late 1960s limited the upstream extent of transport, making transport from Diamond unlikely to be responsible for the increase in 2,3,7,8-TCDD at RM 10 to 12. Records show frequent high-volume diversions of the municipal sewer through a bypass at RM 11.5 during this period, resulting in the discharge of large volumes of Givaudan's wastewater. Estimates of the mass of 2,3,7,8-TCDD discharged from Givaudan are comparable to literature-based estimates of discharges from Diamond. These results provide compelling evidence that Givaudan is a second major source of 2,3,7,8-TCDD and accounts for a significant fraction of the 2,3,7,8-TCDD in the LPR.