Using High-Throughput Paleolimnological Methods to Evaluate the Distribution and Transport of Lead in Northeastern North America

Abstract

Using high-throughput paleolimnological methods, this thesis evaluated anthropogenic Pb deposition along a west-east transect from the Adirondack Mountains, New York, USA (ADIR) region, the Vermont-New Hampshire-Maine, USA (VT-NH-ME) region, and Nova Scotia, Canada (NS) region using 47 ^210^Pb-dated lake sediment records. This thesis reviewed the distribution and transport of trace metals at a global scale, developed a high-throughput analytical method to measure the elemental composition of low-mass aquatic sediment samples, developed a software package to visualize and analyze measurements from many lake sediment records, validated the sensitivity of elemental measurements in lake sediments to watershed-scale disturbance, and evaluated calculated elemental measures to deconvolute multiple sources of trace metals to lake sediment records. Finally, this thesis used focus-corrected Pb inventories to evaluate cumulative deposition and breakpoint analysis to inform west-east transport of Pb in northeastern North America. Peak Pb concentrations decreased from west to east (ADIR region: 52-378 mg kg^-1^, VT-NH-ME region: 54-253 mg kg^-1^, NS: 38-140 mg kg^-1^). Cumulative deposition of anthropogenic Pb also decreased from west to east (ADIR region: 791-1,344 mg m^-2^, VT-NH-ME region: 209-1,206 mg m^-2^, NS: 52-421 mg m^-2^). The initiation of anthropogenic Pb deposition occurred progressively later along the same transect (ADIR region: 1869-1900, VT-NH-ME region: 1874-1905, NS region: 1901-1930). Previous lead isotope studies suggest that eastern Canadian Pb deposition over the past ~150 years has originated from a mix of both Canadian and U.S. sources. The results of this thesis indicate that anthropogenic Pb from sources west of the ADIR region were deposited in lesser amounts from west to east and/or Pb sources reflect less population density from west to east. The timing of the initiation of anthropogenic Pb deposition in the NS region suggests that Pb from gasoline may be an important source in this region. The high-throughput methods developed in this thesis may further the application of paleolimnological studies to regional contaminant transport, contaminated aquatic sediment assessment, and water infrastructure design.

Publication
Ph.D. Thesis (Dalhousie University)
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Dewey Dunnington
Geoscientist, Programmer, Educator