Black carbon in soils: The use of benzene polycarboxylic acids as specific indicators

Tom Miles

Black carbon in soils: The use of benzene polycarboxylic acids as specific indicators

Bruno Glaser, Ludwig Haumaier, Georg Guggenberger and Wolfgang Zech

Institute of Soil Science, University of Bayreuth, 95440 Germany. Fax: ++49-921-552246. Email: bruno.glaser@uni-bayreuth.de

Mitteilungen der Deutschen Bodenkundlichen Gesellschaft (1997) 85: 237 - 240

1. Introduction

Black carbon (BC) is formed during incomplete combustion of biomass. Being highly resistant to microbial and chemical oxidation, it is considered to be a significant sink in the global carbon cycle. Most likely, it is also a source of stable aromatic carbon in soils.

A simple method is presented for the estimation of black carbon (BC) in soil samples. Our method uses benzene polycarboxylic acids (BPCA) as specific indicators for BC, since these compounds long have been known to be formed upon oxidation of coal or carbonized organic materials. The analytical procedure includes hydrolysis, oxidation, sample cleanup, derivatization, and gas liquid chromatography. To test the usefulness of BPCA as marker for BC, we compared the yield of BPCA from charred wood with that from "humic substances" produced in the laboratory by enzymatic browning, non-enzymatic browning and aerobic incubation of barley straw.