1-38 Individual sediment core vertical profiles for DDT (Figure 1-19) also reveal that measurements in sediment cores were in most cases limited to shallow layers (0 to 6 ft), except near the mouth of the <strong>Passaic</strong> <strong>River</strong>, where DDT levels in deeper sediments (14 ft) could be four times higher than in the surface layer (e.g., stations 96A-NWB and 81A-NWB). Notwithstanding that DDT levels in deep sediments (4 ft) of south <strong>Newark</strong> <strong>Bay</strong> may also be elevated (e.g., station 70A- NWB), the high concentrations at the surface suggest the existence of possible on-going sources. Metals. Of the metals that are available in the database, the spatial distribution of mercury, chromium, lead, nickel, arsenic, and cadmium in surface and sub-surface sediments of <strong>Newark</strong> <strong>Bay</strong> and the Kill van Kull are shown in Figures 1-20 through 1-25. Unlike in the lower <strong>Passaic</strong> <strong>River</strong> where metal levels often exceed the ER-M guidelines, only levels of mercury and to a lesser extent chromium and nickel are in excess of the ER-M in <strong>Newark</strong> <strong>Bay</strong>. Mercury concentrations in surface as well as in deeper sediments exceed both the ER-L (150 ng/g) and ER-M (710 ng/g) throughout <strong>Newark</strong> <strong>Bay</strong> into the Kill van Kull (Figure 1-20); the detected concentrations are between 5 to 20 times higher than the medium and low range of ecological effects. As is the case with other contaminants, there are large gaps in mercury measurements in the sub-surface sediments, in particular, between RM1.5 and RM4. A preliminary inspection of the 1976 surface grab sample data of Suszkowski (1978) indicates that mercury levels at that time were similar in magnitude to the results shown on Figure 1-20, generally on the order of 1000 – 10,000 ng/g. Inspection of results from a limited number of borings failed to reveal a consistent pattern, though a more detailed review of these data is warranted. It should be noted that an assessment effort is currently being conducted to better evaluate Berry’s Creek as a potential source of mercury into <strong>Newark</strong> <strong>Bay</strong>. The result of the evaluation will ultimately be integrated into the modeling effort. Throughout <strong>Newark</strong> <strong>Bay</strong>, chromium concentrations in the surface sediment are between the ER-M (370,000 ng/g) and ER-L (81,000 ng/g) values (Figure 1-21). The ER-M is exceeded only once in the Kill van Kull area. In deeper sediments, levels of chromium are somewhat lower than in the surface sediment, except at locations closer to the mouth of the <strong>Passaic</strong> <strong>River</strong>, where deep sediments (12 ft) show elevated chromium concentrations in excess of the ER-M value. Suszkowski’s (1978) surface grab sample results from 1976 were comparable in magnitude, though some results were higher than the concentrations of Figure 1-21, with a number of samples having chromium levels in excess of the ER-M. Except in the proximity of the mouth of the <strong>Passaic</strong> <strong>River</strong>, the levels of lead in <strong>Newark</strong> <strong>Bay</strong> surface sediment generally remain between the ER-M (218,000 ng/g) and ER-L (46,700 ng/g) values (Figure 1-22). Also, in spite of the apparent decrease in lead concentrations in the lower section of <strong>Newark</strong> <strong>Bay</strong>, between RM5.5 and RM6.5, there is an apparent surge in lead concentration in the
Depth (ft) Depth (ft) 0 2 4 6 8 10 12 14 0 2 4 6 8 10 12 14 Depth (ft) 0 2 4 6 8 10 12 14 Depth (ft) 10 10 0 10 0 0 tDDT (ng/g) 0 2 4 6 8 10 12 14 100A- NWB 81A- NWB 10 100 tDDT (ng/g) 1000 72A- NWB 10 10 0 10 0 0 tDDT (ng/g) 44B- NWB 10 10 0 10 0 0 tDDT (ng/g) Depth (ft) 0 2 4 6 8 10 12 14 Depth (ft) Depth (ft) Depth (ft) 0 2 4 6 8 10 12 14 0 2 4 6 8 10 12 14 0 2 4 6 8 10 12 14 70A- NWB 10 10 0 10 0 0 tDDT (ng/g) 96A- NWB RA-03- NWB BCD2- NWB 1-39 10 100 1000 tDDT (ng/g) 10 100 1000 tDDT (ng/g) 10 100 1000 tDDT (ng/g) Figure 1-19. Sediment vertical profiles for DDT in selected cores across <strong>Newark</strong> <strong>Bay</strong>.
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