Superfund Research Program

Sources and Pathways of Urban Heavy Metal Exposure Using Elemental and Isotopic Composition of Environmental Samples

Project Leader: H. James Simpson
Grant Number: P42ES007384
Funding Period: 1995 - 2001

Project-Specific Links

Final Progress Reports

Year:   1999 

This project is focused on the identification of current and previously unrecognized urban sources of environmental lead using dated environmental samples. Samples include airborne particulates; New York Harbor, Hudson River and reservoir system sediment cores; soil, water and sewage sludge. Sources of lead are identified through the techniques of stable isotope analysis complemented by "finger printing" using trace element analysis. These data are essential for development of rational strategies of exposure prevention.

This work has led to these significant gains in understanding of the major sources and pathways of heavy metals in the NYC environment over the last several decades.

• Studies of the sediments from three urban waterbodies (Central Park Lake, Prospect Park Lake and Hillview Reservoir) strongly support the hypothesis that sediment cores collected in urban lakes and reservoirs can provide excellent archives for documenting the history of atmospheric deposition of contaminants to urban centers over time-scales of a century or more. Although this approach has been widely used in remote areas, very little work has previously been reported for large urban centers.
• A long history of incineration of solid waste appears to have been the largest source of atmospheric Pb to NYC during much of the 20th century. Widespread historical use of solid waste incinerators in the US and Europe suggests that these sources may have provided a more important contribution to atmospheric lead and several other metals to many urban centers than has previously been recognized. Fallout of lead from leaded gasoline is also an important source.
• Atmospheric deposition rates of Pb and several other metals including Hg to the core area of NYC over the last century are considerably higher than previously believed.
• Emissions from another important source of atmospheric Pb, smelting of ores, were documented in sediment cores collected from the Arthur Kill, the harbor channel area between Staten Island and New Jersey. For many years a large lead smelter operated on the new Jersey shores of the Arbor Kill. Extremely high Pb and Zn levels were found in sediment depth sections that accumulated in the early part of the 20th century. This time period is consistent with economic records of primary smelting industry, but not the period of maximum lead deposition derived from Central Park Lake sediment cores.
• Distinct chronologies of stable Pb isotope ratios are apparent in several areas of the Hudson River watershed. These enable identification of lead sources and should be especially useful in documenting contaminant transport downstream from the Upper Hudson River as well as providing additional stratigraphic markers within sediment cores of that area. This latter information should prove very useful also for estimates on in situ dechlorination rates being proposed as part of Project 1.
• With supplemental funding from NYS DEC, Hg analyses from a much larger set of our sediment core samples confirmed and reinforced NOAA's ranking of NY/NJ harbor area as one of the worst Hg polluted estuaries in the nation.