Airborne Contamination of Forest Soils by Carbonaceous Particles from Industrial Coal Processing

Abstract

In the German Ruhr‐area industrial coal processing emitted large amounts of carbonaceous particles for a century until 1970. Our objectives were to detect the presence of airborne carbonaceous particles and assess their impact on the chemical structure of soil organic matter in two forest soils (Podzols) with potential sources of carbonaceous particles approximately 10 to 30 km away. Contamination was not visible macroscopicaily. Organic matter was characterized in bulk soils and in particle‐size separates by elemental analysis, magnetic susceptibility measurement, reflected light microscopy, and 13C solid‐state nuclear magnetic resonance (NMR) spectroscopy. Organic and mineral horizons contained carbonaceous particles including char, coke, and bituminous coal from coal combustion, coking, coal processing, and steel production. In the organic horizons of both soils we observed a material high in magnetic susceptibility (max. 109 × 10−8 m3 kg−1), whereas in the mineral horizons only the Podzol with an intense intermixing moder‐type humus had high magnetic susceptibly. This Aeh horizon was extremely rich in organic carbon (139.4 g organic C kg−1), concentrated in the 20 to 2000 µm size separates. In the second Podzol, like in many natural soils, C concentrations were largest in the <20 µm separates. Bloch decay 13C magic angle spinning (MAS) NMR spectroscopy revealed a highly aromatic structure of the carbonaceous particles. Airborne carbonaceous particles formed a macroscopically indistinguishable mixture with natural soil organic matter and could be present in many soils neighboring industrialized areas.

Carbon-13 solid-state NMR of soil organic matter - using the technique effectively

“…Crosspolarization is also less efficient for carbons remote from H, as in the polycondensed aromatic structures of coal (Pruski et al 1990;Zhang and Maciel 1990;Jurkiewicz and Maciel 1995a). Recent studies have highlighted the importance of charcoal as a passive or inert pool in SOM, as well as its underestimation by conventional CPMAS NMR (Skjemstad et al 1996(Skjemstad et al , 1999aGolchin et al 1997a, b;Schmidt et al 1999Schmidt et al , 2000Smernik and Oades 2000a, b;Smernik et al 2000).…”

Chemical Composition of Organic Matter in Extremely Acid, Lignite‐Containing Lake Sediments Impacted by Fly Ash Contamination

“…This pattern was also found by previous studies on size fractions of soils summarized by Ladd et al (1977) and Bonde et al (1992) Additionally, in lake sediments, microorganisms such as algae may be present in the fine particle size fractions. The higher OC and N in the 200‐ to 6.3‐μm fractions together with C to N ratios of >43 suggest that these fractions were subject to contamination with carbon particles resulting from airborne lignite combustion products (Schmidt et al, 2000).…”

“…4) could be derived from carbonaceous particles present in lignite‐derived combustion products (e.g., fly ash), which consist exclusively of aromatic material. These materials were shown to accumulate preferentially in the fine sand and coarse and medium silt fractions (Rumpel et al, 1998b; Schmidt et al, 2000). This is in contrast to the inorganic fly ash particles, which may accumulate preferentially in the silt and clay fraction (see above; Table 3; Rumpel et al, 1998a).…”

Artifact preservation and post-depositional site-formation processes in an urban setting: a geoarchaeological study of a 19th century neighborhood in Detroit, Michigan, USA

“…The carbonaceous vesicular AMPs, which are visibly cinder-like, and the siliceous non-spherical grains containing carbonaceous inclusions, are also interpreted as coal combustion products (Table 2). Coal-related wastes are often components of urban soils (Bridges, 1991;Schmidt et al, 2000;Koschke et al., 2011). Coal-fired steam locomotives were used heavily at the MCS before WWII, and were still in use as recently as 1958 (Kavanaugh, 2001).…”