Multi-decadal Black Carbon Variations Reveal Anthropogenic Influences on Fire in the Post-Colonial Chesapeake Bay Watershed

A Post-Colonial settlement record of sedimentary black carbon (BC) from the Chesapeake Bay was used to reconstruct the impact of climate and anthropogenic activities on regional fire regime at multi-decadal time-scales. The abundance of BC in this sediment core varies between 0.21 - 0.75 % per gram of dry weight (gdw), while the abundance of OC varies between 0.81 and 1.6% gdw. The downcore stable carbon isotopic ratio of BC as well as polycyclic aromatic hydrocarbon isomer ratios, demonstrate that since 1680 Common Era (CE), sedimentary BC in the Chesapeake Bay watershed resulted largely from anthropogenic combustion of biomass for fuels (i.e. fuelwood). Moreover, trends in these data suggest that emission of BC resulting from the combustion of such material peaked during the mid-1800s and may have altered hydrological regimes by increasing regional precipitation during this time period.