Acquisition of a hydropyrolysis unit for pre-treatment of soils for isotopic analysis and black carbon quantification

Cornell University, Ithaca NY

Investigators

Abstract

We will quantify the black carbon contents at six sites of the Long-Term Ecological Research (LTER) network in an effort to understand the landscape-level distribution of black carbon in different environments reaching from Alaska to Florida. In addition, we will measure black carbon contents in a large number of samples collected by the United States Geological Survey in a 40-kilometer grid and generate a map of its distribution for several regions in the United States. This information will be fed into a data base for the National Soil Carbon Network (http://www.fluxdata.org/nscn/SitePages/Home.aspx) to develop a learning tool for assessing soil carbon changes. The data obtained by hydropyrolysis will be compared with those obtained by nuclear magnetic resonance spectroscopy and UV-oxidation procedures. We will develop a conversion tool to calculate black carbon contents using mid-infrared (MIR) spectroscopy that is the most rapid tool to quantify carbon forms in soil. During forest and savanna fires, large quantities of char may be produced and this so-called black carbon is found to be ubiquitous. Whether this material accumulates in soil or is exported by erosion, leaching or decomposition, is largely unknown. Black carbon itself is very recalcitrant and may also constitute a sink for atmospheric carbon dioxide. A better knowledge of the global distribution of black carbon will help answer several important questions about the global carbon cycles, about the relevance of black carbon in soil productivity and in which way soil organic matter will change with warming as a result of climate change or with cultivation as a result of land use changes. Several methods are available for measurement of soil black carbon content, but most of them only measure part of the continuum of chemical substances that make up black carbon. Hydropyrolysis offers the potential for an inexpensive and rapid analysis method with the same accuracy as the best currently available methodology, and would therefore make a large number of analyses possible. The ability to quantify isotopes through the separation procedure in hydropyrolysis affords the opportunity to quantify turnover times. The versatility of this analytical tool will aid in refining quantification and separation to accommodate different research objectives by recognizing that black carbon is a continuum of carbon forms.