Radionuclide, radiogenic lead isotope and trace metal analyses on fine-grained sediment cores collected along 160 km of the upper and tidal Hudson River were used to examine temporal trends of contaminant loadings and to develop radiogenic lead isotopes both as a stratigraphic tool and as tracers for resolving decadal particle transport fluxes. Very large inputs of Cd, Sb, Pb, and Cr are evident in the sediment record, potentially from a single manufacturing facility. The total range in radiogenic lead isotope ratios observed in well-dated cores collected about 24 km downstream of the plant is large (e.g., maximum difference in 206Pb/207Pb is 10%), characterized by four major shifts occurring in the 1950s, 1960s, 1970s and 1980s. The upper Hudson signals in Cd and radiogenic lead isotopes were still evident in sediments collected 160 km downstream in the tidal Hudson. The large magnitude and abrupt shifts in radiogenic lead isotope ratios as a function of depth provide sensitive temporal constraints that complement information derived from radionuclide analyses to significantly improve the precision of dating assignments. Application of a simple dilution model to data from paired cores suggests much larger sediment inputs in one section of the river than previously reported, suggesting particle influxes to the Hudson have been underestimated.

Consistent observations of elevated mercury concentrations in freshwater fish in all areas of New Jersey have raised questions about the sources of mercury entering aquatic systems and aquatic food chains in New Jersey. Mercury depositing in New Jersey waterbodies could originate from global sources, large-scale regional sources and/or local sources, including in-state sources. The first year of this study was designed to examine whether historic mercury deposition rates (fluxes) to waterbodies in different parts of New Jersey are different. Such differences could imply impacts from relatively local sources. The first year study utilized sediment cores collected at six sites throughout the state between September 2000 and December 2001 (Woodcliff Lake, Wawayanda Lake, Mountain Lake, Imlaystown Lake, Parvin Lake and Tuckerton marsh core). The results in NJ lakes were generally comparable to each other and to recent mercury fluxes in the Great Lakes area suggesting a large-scale regional influence (Kroenke 2003; Kroenke et al. 2002). However, the Woodcliff Lake site in Assessment of Historical and Current Trends in Mercury Deposition to New Jersey Aquatic Systems through Analysis of Sediment/Soil Cores YEAR 2

Radionuclide, stable lead isotope and trace metal analyses on fine-grained sediment cores collected along a 24-mile reach of the upper Hudson River were used to establish temporal trends of contaminant loadings, to establish stable lead isotopes as an additional stratigraphic tool, and as tracers for resolving particle transport fluxes over periods of decades. Very large contaminant inputs of Cd, Sb, Pb and Cr were evident in the sediment record. One potential large source for these metals was from a pigment manufacturing facility in Glens Falls, NY. The total range in stable lead isotope ratios observed in well-dated cores from about 15 miles downstream of the potential metal inputs was large (e.g., maximum difference in 206Pb/207Pb is 10%) and characterized by four major shifts occurring in the 1950s, 1960s, 1970s and 1980s. The temporal trend in 206Pb/207Pb has been used to establish precise dating of a sediment core from 24 miles further downstream. The large magnitude and abrupt shifts in stable lead isotope ratios preserved in upper Hudson sediment cores provide a way to significantly improve dating models, based only on radionuclide analyses. Cadmium, lead and antimony were identified as quite sensitive tracers of upper Hudson sediments due to the magnitude of contamination and the lack of significant additional downstream sources of these contaminant metals. Metal measurements in a pair of sediment cores located 24 miles apart were used to constrain relative fluxes of sediment entering the river between the two coring locations, with sediment sections deposited between the early 1960s and the late 1970s in these two cores suggesting that 3–4 times more sediment entered the river between the two coring sites than was transported from upstream. These dilution factors agree very well with estimates based on suspended sediment measurements during a flood event in April 1994 and with estimates based on mechanistic model of suspended sediment transport between 1977 and 1992.

It is generally assumed that declining atmospheric lead concentrations in urban centers during the 1970s and 1980s were due almost entirely to the progressive introduction of unleaded gasoline. However, most environmental data are from monitoring programs that began only two to three decades ago, which limits their usefulness. Here, trace metal and radionuclide data from sediment cores in Central Park Lake provide a record of atmospheric pollutant deposition in New York City through the 20th century, which suggests that leaded gasoline combustion was not the dominant source of atmospheric lead for NYC. Lead deposition rates, normalized to known Pb-210 atmospheric influxes, were extremely high, reaching maximum values (>70 μg cm(-2) yr(-1)) from the late 1930s to early 1960s, decades before maximum emissions from combustion of leaded gasoline. Temporal trends of lead, zinc, and tin deposition derived from the lake sediments closely resemble the history of solid waste incineration in New York City. Furthermore, widespread use of solid waste incinerators in the United States and Europe over the last century suggests that solid waste incineration may have provided the dominant source of atmospheric lead and several other metals to many urban centers.

Analysis of sections from dated sediment cores were used to establish geographic distributions and temporal trends of chlorinated hydrocarbon contaminant levels in sediments from natural waters of the Hudson River basin. Radiometric dating was based primarily on the depth distribution of 137(Cs) in the cores and on the occurrence of detectable levels of 7(Be) in surface sediment samples. Eighteen sampling sites included several along the main stem of the Hudson, its major tributaries, and components of the New York/New Jersey (NY/NJ) harbor complex. Drinking-water reservoirs were sampled to place upper limits on atmospheric inputs. Core sections were analyzed for polychlorinated biphenyls (PCBs), 1,1,1-trichloro-2,2-bis(p-chlorophenyl) ethane (DDT)-derived compounds, chlordane, and dioxins. Sediment concentrations of most contaminants at most sites have decreased significantly since the mid-1960s. The data provide a basinwide perspective on major point-source inputs of PCBs to the upper Hudson River and of 2,3,7,8-tetrachlorodibenzo-p-dioxin and DDT to the lower Passaic River. Evidence was found for significant but poorly characterized sources of PCBs and chlordane to the western NY/NJ harbor, and of highly chlorinated dioxins to the upstream sites on the main stem of the Hudson. The results indicate that analysis of dated sediment samples is a most effective and efficient monitoring tool for the study of large-scale geographic and temporal trends in levels of particle-associated contaminants.