Newark Bay Study - Passaic River Public Digital Library
Newark Bay Study - Passaic River Public Digital Library
Newark Bay Study - Passaic River Public Digital Library
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1-24<br />
chemicals and biological tissues monitored), spatial (i.e., only few locations covered), and temporal<br />
(i.e., not often enough) distribution of information in the <strong>Bay</strong>. It is the intention of the Field<br />
Sampling Program performed by TSI as part of its Remedial Investigation Work Plan (TSI, 2004) to<br />
begin to address the data gaps in the study domain.<br />
The most pertinent plots are presented and discussed as part of this modeling plan and the<br />
main observations about the spatial and temporal relationships that exist within the domain for the<br />
selected chemicals are presented below. The discussions are not intended to be exhaustive, but<br />
rather a summary of the most important data features and availability.<br />
Polychlorinated Biphenyls (PCBs). Figure 1-7 shows total PCBs as the sum of congeners (closed<br />
circles ●), sum of homologs (open circles ○), and the sum of coplanar congeners (open triangles ª) in<br />
surface sediments and with depth in the <strong>Newark</strong> <strong>Bay</strong>-Kill van Kull domain. The data reveals that at<br />
every river mile within the <strong>Bay</strong> and at a few locations in the Kill van Kull, both the 23 ng/g ER-L<br />
and the 180 ng/g ER-M values are exceeded. Since they are a specific subset of the PCB congeners,<br />
the concentrations of coplanar congeners are systematically lower than the total PCBs. There is no<br />
noticeable spatial trend in the surface sediments within <strong>Newark</strong> <strong>Bay</strong>. Lower detections were<br />
encountered in the Kill van Kull, but very few samples were available for review, some of which did<br />
exceed the guidelines. The average total PCB level in <strong>Newark</strong> <strong>Bay</strong> surface sediment is 332 ng/g in<br />
the top 12 cm, whereas the highest concentration was 1990 ng/g at approximately RM3.8 into the<br />
<strong>Bay</strong>. In general, levels of PCBs decrease slightly with depth, except at the mouth of the <strong>Passaic</strong><br />
<strong>River</strong> where deeper sediments (3 to 6 ft and 7 to 13 ft) have concentrations of coplanar PCBs similar<br />
to or even exceeding what is observed in surface sediments. Yet, it is not uncommon to find high<br />
levels of PCBs in deeper layers of sediments into <strong>Newark</strong> <strong>Bay</strong>, as is the case at RM6.9 where<br />
concentrations of coplanar PCBs are higher in deeper sediments (3 to 6 ft) than at 0.5 to 3 ft. Note<br />
that total PCB measurements are available only for the layer between 0 and 4.5 ft, and are spatially<br />
limited to either the mouth of the <strong>Passaic</strong> <strong>River</strong> or to a section between RM4 and RM5.2.<br />
Vertical concentration profiles on selected cores show different patterns (Figure 1-8). Data<br />
from three cores collected close to each other show consistently high surface and subsurface<br />
coplanar PCB concentrations in one core 100A-NWB, and decreasing levels with increasing depth in<br />
the other cores (99A-NWB and 98A-NWB, northern <strong>Newark</strong> <strong>Bay</strong>). In the mid-section of the <strong>Bay</strong>,<br />
decreasing PCB levels with depth were also noted, although in many cases there were no<br />
measurements performed on sediments deeper than 4.5 ft. Note that the plotted sediment core<br />
concentrations are those reported at the top of the depth intervals, although, like in core number<br />
98A-NWB (mouth of the <strong>Passaic</strong> <strong>River</strong>), the sampled intervals are very small: top 0.17 ft, between<br />
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<br />
the PCBs reside in the upper layer, since it is located in a low depositional area. However, the<br />
interpretation of the depth profiles to reconstitute the history of deposition is limited in the absence