Trace metals in Long Island Sound

The Distribution of Trace Metals in Long Island Sound Sediments.137... 

Our observations about the distribution of trace metals in Long Island Sound, as elucidated by our studies of the behaviors of Th and Pb, lead us to the following generalizations ... 

McCaffrey, R.J., and Thomson, J. (1980) A record of the accumulation of sediments and trace metals in a Connecticut salt marsh. In Advances in Geophysics, Estuarine Physics and Chemistry Studies in Long Island Sound (Saltzman, B., ed.), pp. 165-236, Academic Press, New York. 

Greig, R.A. and D.R. Wenzloff. 1977. Trace metals in finfish from the New York Bight and Long Island Sound. Mar. Pollut. Bull. 8 198-200. 

Benninger, L.K., Aller, R.C., Cochran, J.K., and Turekian, K.K. (1979) Effects of biological sediment mixing on the 210Pb chronology and trace metal distribution in a Long Island Sound sediment core. Earth Planet. Sci. Lett. 43, 241-259. 

About 15 km to the west of New Haven Harbor the Housatonic River with its heavily polluted tributary, the Naugatuck River, empties into the Sound. (The confluence occurs below the last dam on the Housatonic.) This river supplies a significant amount of trace metals to the adjacent part of Long Island Sound, mainly in particulate form (Turekian, 1971). This contrasts sharply with the Quinniapiac River and demonstrates that the construction of dams is certainly one important factor in inhibiting transfer of metal-polluted sediments to the estuarine zone. 

A number of cores collected from central Long Island Sound have been analyzed for trace metals as a function of sediment depth (Thomson et al., 1975 Turekian, 1979 Benninger et al., 1979). They show roughly the same patterns for Cu, Zn, and Pb (Fig. 11) a roughly exponential decrease in concentration with depth. At greater depths there are occasional peaks of high concentrations. 

Fig. 11. The distribution of trace metals in cores from Long Island Sound, (a) Location map of cores described in this article, (b) Core 1148 data from Thomson et al., 1975. (c) Core NWC-102975 data from Benninger et al. (1979). (d) Core 1036 data from Turekian (1979).

As Fig. 11 shows, there is some variability in the integrated trace-element contents of cores from central Long Island Sound. These sediments are not located near intense sources of trace metals nor are there major grain-size differences. As we will show later, the differences in both metal concentrations and inventories can be related primarily to the intensity and depth of biological mixing of the sediment column. 

In the previous sections the case was made for two major classes of trace-metal impingement on Long Island Sound. One type is the supply by polluted streams and sewer outfalls, which, on the basis of the distributions of trace metals in the sediments and near-shore suspensionfeeding bivalves, was inferred to be predominantly in the form of particles. The other is atmospheric supply, some part of which presumably is in... 

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