Newark Bay Study - Passaic River Public Digital Library

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chemicals and biological tissues monitored), spatial (i.e., only few locations covered), and temporal
(i.e., not often enough) distribution of information in the Bay. It is the intention of the Field
Sampling Program performed by TSI as part of its Remedial Investigation Work Plan (TSI, 2004) to
begin to address the data gaps in the study domain.
The most pertinent plots are presented and discussed as part of this modeling plan and the
main observations about the spatial and temporal relationships that exist within the domain for the
selected chemicals are presented below. The discussions are not intended to be exhaustive, but
rather a summary of the most important data features and availability.
Polychlorinated Biphenyls (PCBs). Figure 1-7 shows total PCBs as the sum of congeners (closed
circles ●), sum of homologs (open circles ○), and the sum of coplanar congeners (open triangles ª) in
surface sediments and with depth in the Newark Bay-Kill van Kull domain. The data reveals that at
every river mile within the Bay and at a few locations in the Kill van Kull, both the 23 ng/g ER-L
and the 180 ng/g ER-M values are exceeded. Since they are a specific subset of the PCB congeners,
the concentrations of coplanar congeners are systematically lower than the total PCBs. There is no
noticeable spatial trend in the surface sediments within Newark Bay. Lower detections were
encountered in the Kill van Kull, but very few samples were available for review, some of which did
exceed the guidelines. The average total PCB level in Newark Bay surface sediment is 332 ng/g in
the top 12 cm, whereas the highest concentration was 1990 ng/g at approximately RM3.8 into the
Bay. In general, levels of PCBs decrease slightly with depth, except at the mouth of the Passaic
River where deeper sediments (3 to 6 ft and 7 to 13 ft) have concentrations of coplanar PCBs similar
to or even exceeding what is observed in surface sediments. Yet, it is not uncommon to find high
levels of PCBs in deeper layers of sediments into Newark Bay, as is the case at RM6.9 where
concentrations of coplanar PCBs are higher in deeper sediments (3 to 6 ft) than at 0.5 to 3 ft. Note
that total PCB measurements are available only for the layer between 0 and 4.5 ft, and are spatially
limited to either the mouth of the Passaic River or to a section between RM4 and RM5.2.
Vertical concentration profiles on selected cores show different patterns (Figure 1-8). Data
from three cores collected close to each other show consistently high surface and subsurface
coplanar PCB concentrations in one core 100A-NWB, and decreasing levels with increasing depth in
the other cores (99A-NWB and 98A-NWB, northern Newark Bay). In the mid-section of the Bay,
decreasing PCB levels with depth were also noted, although in many cases there were no
measurements performed on sediments deeper than 4.5 ft. Note that the plotted sediment core
concentrations are those reported at the top of the depth intervals, although, like in core number
98A-NWB (mouth of the Passaic River), the sampled intervals are very small: top 0.17 ft, between
2.8 and 2.9 ft, exactly at 4.6 ft, and at 6 ft. The profile of that core, however, suggests that most of
the PCBs reside in the upper layer, since it is located in a low depositional area. However, the
interpretation of the depth profiles to reconstitute the history of deposition is limited in the absence