A spatial and statistical investigation of dioxin-furan contamination in the sediments of the Hudson-Raritan Estuary

Sediment sampling results from a number of studies were examined for the spatial, statistical and temporal patterns in dioxin concentration and dioxin congener patterns. Principal component analysis and cluster analysis were used to group the sediment samples into a smaller set of variables. The spatial and temporal distribution of these derived data were examined with respect to industrial activity, cultural trends and industrial accidents. A GIS was used to analyze sample points for spatial correlation with sources of dioxin contamination. Time horizons were established using Cesium 137 and Lead 210 activities and historical bathymetric.; The results of these analyses indicate that current deposition of dioxin contamination in the Harbor Estuary is dominated by higher chlorinated dioxin furans from combustion sources, such as automobiles, trucks and to a more limited extent, municipal and industrial incineration. Subsurface samples show a more complex array of dioxin-furan congener patterns with numerous dioxin sources including combustion sources, chemical discharges and sewage treatment plants. Some of the patterns are not found in the dioxin-furan source literature, they may result from historical industrial or combustion processes that have been banned or discontinued. The radioisotope and bathymetric dating procedures established time frames for the dioxin-furan congener patterns.; The most significant single source of dioxin contamination in the Harbor Estuary is the former Diamond Alkali Site, on the Lower Passaic River. Long-term production of 2,4,5-trichlorophenoxy acetic acid (2,4,5-T) and an industrial accident in 1960 released massive amounts of dioxin contamination into the adjacent Passaic River, leaving a distinct pattern of dioxins, primarily 2,3,7,8-tetrachlorinated dibenzo dioxin. Two of the clusters identified result from contamination at this site; one represents long term production of 2,4,5-T, while the other is a unique signature from the 1960 explosion and fire. Although largely buried this hot spot of contamination is close to the surface in a number of locations. This represents a threat to biota due to the potential for reintroduction into biologically active zone as well as a barrier to human use of the Lower Passaic River for manufacturing and recreational boating.