THE AFFECT OF LAND USE CHANGE ON STABLE ISOTOPE (δ13C AND δ15N) VALUES IN CONNECTICUT WETLANDS DURING THE HOLOCENE

Colonial settlement in southern New England was rapid and widespread. Old growth forests were cleared for agriculture, charcoal burning, or mill damming from the early seventeenth century to the late nineteenth century. Upon the decline of the agrarian lifestyle, forests were left to regrow and mature to their natural state. Extensive land use change greatly affected the soils, vegetation, and wetlands in the surrounding areas. Wetland responses to local geology and anthropogenic impact are site specific, and can be useful indicators of land use change and resulting nutrient and sediment fluxes. In this study, four sediment cores were taken from wetlands in eastern and western Connecticut. ASYF1 is a push core taken from a paleodam in the Yale State Forest in Ashford, CT. ASBP1 is a vibracore taken from an earthen beaver dam in Ashford, CT. ESBB1 is a push core taken from the Natchaug State Forest in Eastford, CT. PT1 is a short push core from a dam Putnam County, CT. Of the four cores, ASYF1, ASBP1, and ESBB1 are three meters and PT1 is one meter in length. Age models are being developed using radiocarbon data from bark and roots throughout the core. The age for ASYF1 at a depth of 74 cm is 220 ± 66 calendar years BP. The age for ASBP1 at a depth of 106 cm is 4040 ± 41 cal yr BP. The age for ESBB1 at depths 29 cm and 114 cm are 362 ± 54 and 14,450 ± 346 cal yr BP, respectively. The goal of this study is to determine the isotopic signature of the New England Anthropocene by observing trends in isotopic carbon (δ¹³C) and nitrogen (δ¹⁵N) values in sediment cores from CT wetlands. Trends in heavy metal concentrations will be measured as well. Each core was cut in half, cleaned, described at the University of Connecticut, and was either archived or used for sampling. Samples from each core were taken in 2 cm increments at the top and bottom of each stratigraphic unit. The samples were split and dried at 50°C. Loss on ignition (LOI) was used to estimate total organic matter content. Dried, homogenized samples were prepared for analysis on a Thermo Delta Advantage mass spectrometer in continuous flow mode connected to a Costech Elemental Analyzer via a ConFlo III at Union College. Total C, total N, δ¹³C, δ¹⁵N, as well as trace metals such as lead (Pb) and copper (Cu) will be analyzed.