HISTORIC TRACE METAL ACCUMULATION IN SLUICE POND, MA: LINKAGES BETWEEN INDUSTRY AND THE ENVIRONMENT

Sluice Pond, Lynn, MA is located approximately 3.2km NW of downtown Lynn, and is 50 acres with a maximum water depth of 19.8 m. Lynn has been home to heavy industrial activity since the 1800’s, famous for, but not limited to its shoe industry. Therefore, it is likely that changes in trace metals present in the sediment of Sluice Pond correlate with the historical record of industrial influence. The purpose of this study was to relate trace metal concentrations (Pb, Cu, Cd, Cr, Zn, As, Ag) to industrial activity that has occurred in the city. A modified Kullenberg corer was used to obtain an undisturbed core from the deep hole of Sluice Pond (SP09KC1; l = 145cm; z = 19.2m). The sediment water interface was preserved, and the upper 20cm of the core was extruded in the field at 0.5cm intervals using trace metal clean tools. The remaining 125cm of core was split in the lab. The core was analyzed using magnetic susceptibility, loss on ignition, trace metals concentrations (using flame atomic absorbance spectrometry of partially digested sediments), and ²¹⁰Pb and ¹³⁷Cs radioactive isotope age modeling. The age model results in sediment rates of ~0.28cm/a, and allows the correlation of the sediment record to local industrial history. Pb concentrations increase gradually from the late nineteenth century until the mid 1970’s, with moderate amplitude fluctuations during the 1950’s, 60’s, and early 70’s . Pb concentrations decrease after the mid 1970’s, soon after the EPA began issuing its first reduction standards of lead in gasoline. Cu concentrations increase abruptly at about 1910 and stay high until the 1950’s, when concentrations decrease to intermediate values with large amplitude fluctuations until present day. Cd concentrations exhibit a general increasing trend through time, and Cr concentrations are relatively constant with a peak in the late 1970’s and early 80’s. Magnetic susceptibility values are elevated in this upper section of core as compared to lower strata with a maximum value of 44.7 SI units at about 25cm depth (early 1920’s). This record has similar features to the Pb and Cu history of deposition, suggesting that the susceptibility values in Sluice Pond are related to anthropogenic affects. The trace metal depositional history of Sluice Pond illustrates anthropogenic influence on this urban pond.