Effects of Temperature and Time (130 Years) on Surface Charges and Chemical Properties of Black Carbon
EMSL Project ID
18899
Abstract
In recent years, geochemical and biological properties of black carbon (BC) have received increasing attention owing to its potential importance in a wide range of biogeochemical processes. BC refers to the residues of incomplete combustion of biomass and fuel. Comparing to other organic matters, BC is more stable in the environments and can be found in atmospheric aerosols, ice, off-shore and deep-sea sediments and soils. Long-term oxidation process can lead BC to have more surface oxygen-containing functional groups. However, no field research has been conducted to describe oxidation process of BC in terrestrial ecosystems. The objective of this proposal is to investigate the change of BC properties over time and different temperature regimes and to characterize the biogeochemical properties of BC. We took BC samples from remnants of historic charcoal blast furnaces in the eastern United States and Canada. Most historic charcoal blast furnace sites were abandoned at a similar time (around 1880s) due to the depletion of forests and the replacement of charcoal by anthracite. Sixteen furnace sites were collected, from Quebec to Alabama, along a climosequence. The recently made BC sample was also obtained from Hopewell Furnace National Historic Sites and is assumed to be the time-zero BC sample for investigating the effect of time on BC properties. We hypothesize: (1) negative charges of BC increase and positive charges decrease over long periods of time; (2) greater temperature increases the proportion of more negative charges on BC surfaces. Chemical and physical characteristics of functional groups of BC will be measured by both wet chemical (surface charges) and spectroscopic (FTIR, NMR, XPS: X-ray photoelectron spectroscopy) techniques. We propose to measure NMR and XPS at EMSL, in which NMR and XPS measurements can show the oxidative states of BC samples. We expect that historic BC will have more negative charge and less positive charge compared to the contemporary BC sample. The temperature will further enhance the negative charge and decrease the positive charge, especially the BC samples from southern furnace sites that were exposed to a higher mean annual temperature.
Project Details
Project type
Exploratory Research
Start Date
2006-07-20
End Date
2007-10-01
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Cheng C.H., and J. Lehmann. 2009. Ageing of black carbon along a temperature gradient. Chemosphere 75:1021-1027.
Nguyen BT, JC Lehmann, J Kinyangi, R Smernik, and MH Engelhard. 2008. "Long-term Black Carbon Dynamics in Cultivated Soil." Biogeochemistry 89(3):295-308. doi:10.1007/s10533-008-9220-9