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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1-14<br />
Bottom sediments were also characterized in detail as part of this early sampling program<br />
(~100 surface sediment samples). The results indicated that the surface sediments of the northern<br />
region of <strong>Newark</strong> <strong>Bay</strong> are primarily composed of particulate material having a grain size that is<br />
representative of silt. The lower Hackensack <strong>River</strong> sediments have a somewhat coarser texture than<br />
the lower <strong>Passaic</strong> <strong>River</strong> and northern <strong>Newark</strong> <strong>Bay</strong> sediments. The sediment composition becomes<br />
coarser in texture in the direction of South <strong>Newark</strong> <strong>Bay</strong>, a trend that likely reflects the more intense<br />
long-term dredging activity and relatively high current speeds in that area, particularly in the Kill van<br />
Kull. Surficial bottom sediment concentrations were also measured, with a focus on levels of total<br />
organic carbon (TOC) and 8 metals: Hg, Cd, Pb, As, Cu, Zn, Cr and Ni. The concentrations of<br />
these constituents will be discussed in a later section of this report.<br />
Suszkowski used the 1976 monthly monitoring data, supplemented by additional sources of<br />
information on velocity profiles at the 4 <strong>Newark</strong> <strong>Bay</strong> boundaries, to develop a detailed inorganic<br />
solids balance for the system. The approach was to evaluate the surface and bottom layer flows at<br />
each of the four points of entry to the <strong>Bay</strong> (discussed above), and to then assign the observed<br />
average TSS concentration to each of these. (It is of interest to note that the boundary at the <strong>Passaic</strong><br />
<strong>River</strong> had a distinctly different TSS profile than the other locations, with the surface layer TSS being<br />
consistently higher than the bottom layer TSS concentration.) The product of the flow and TSS<br />
concentration in the surface and bottom layers yields an estimate of the mass flux rate, and the<br />
difference between the surface and bottom layer fluxes represents an estimate of the net flux across<br />
each <strong>Newark</strong> <strong>Bay</strong> boundary. Additional internal sources of solids, including TSS inputs from<br />
wastewater treatment plants, urban runoff and phytoplankton production were also quantified.<br />
Finally, a net solids balance for the entire <strong>Bay</strong> was obtained by evaluating the sum of all of these<br />
inputs.<br />
The results of Suszkowski’s solids balance analysis are summarized on Figure 1-3. It is<br />
evident from these results that the <strong>Passaic</strong> <strong>River</strong>, Kill van Kull and Arthur Kill were all net sources<br />
of TSS to <strong>Newark</strong> <strong>Bay</strong>, while the Hackensack <strong>River</strong> was a net sink of solids at the time of this<br />
investigation. This latter finding was recently confirmed by simulations performed with the <strong>Newark</strong><br />
<strong>Bay</strong> model by Pence (2004). The simulations involved the initialization of a particle concentration<br />
of 1 mg/L in the <strong>Passaic</strong> <strong>River</strong>, on a monthly basis, and then tracking the movement over these<br />
particles over the course of an annual cycle. The particles tended to move from the <strong>Passaic</strong> <strong>River</strong>,<br />
into <strong>Newark</strong> <strong>Bay</strong>, and then left <strong>Newark</strong> <strong>Bay</strong> by transport into the Hackensack <strong>River</strong>, or by transport<br />
out of the system in the surface layers of the Arthur Kill and Kill van Kull. The difference in<br />
transport regimes for the Hackensack and <strong>Passaic</strong> <strong>River</strong>s is partly explained by the relatively low<br />
freshwater flow in the Hackensack <strong>River</strong>, as this facilitates the upstream transport of solids from the<br />
<strong>Bay</strong>. Additionally, during high flow events there is relatively little upstream storage in the <strong>Passaic</strong><br />
<strong>River</strong>, so peak flow rates propagate through the system with relatively little attenuation. This differs<br />
from the situation in the Hackensack <strong>River</strong>, where upstream reservoir storage will absorb many of