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

Abstract

In the Lusatian lignite mining district of eastern Germany, extremely acid lakes developed during ground water rising after exploitation of lignite in open-cast mines. The reasons of plant colonization (Juncus bulbosus L.) of some lakes exhibiting moderate pH values while others remain extremely acid and unvegetated are unknown. Alkalinity gain may be achieved by addition of alkaline materials and/or decomposition of organic matter. Our objective was to examine fly ash deposition and the resulting changes in organic matter composition in the uppermost 0 to 5 cm of the sediment sampled from vegetated and unvegetated lakes. Bulk soil and particle size fractions were analyzed for elemental composition, magnetic susceptibility, and chemical structure of the organic matter by 13C solid-state nuclear magnetic resonance (NMR) spectroscopy. The lignite content of the samples was estimated by 14C activity measurements. The pH values decreased with increasing depth and the changes in pH were found to be correlated with changes in magnetic susceptibility. Carbon and nitrogen contents were found to decrease with increasing depth. The C to N ratios are consistent with the (i) the presence of decomposing plant residues and/or microbial material such as algae in the upper 0 to 5 cm of the sediment and (ii) the dominance of lignite in the layers below this depth as confirmed by 14C activity measurements. The structural analyses of the particle size separates from the 0- to 5-cm depth were consistent with the presence of organic matter derived from plant material. This study confirms that fly ash is an important source of alkalinity in the upper 0 to 5 cm of the sediment that enhanced plant growth and led to enrichment of the sediment with organic matter derived from plant material.

An appraisal of the potential use of fly ash for reclaiming coal mine spoil

“…Similarly, adding lime in conjunction with coal and lignite FAs, in combination with other amendments (at different doses), such as farmyard manure (FYM), sewage sludge, paper mill sludge and lime mud raised the pH in a variety of acidic soils (Wong and Lai, 1996;Anguissola Scotti et al, 1999;CFRI, 2000aCFRI, , b, 2001aCFRI, , b, 2002aUlrichs et al, 2005;Ram et al, 2007b). Several studies have explored the liming properties of FA on different soils and coal mine spoils (Taylor and Schuman, 1988;Srivastava and Chhonkar, 2000;Chabbi and Rumpel, 2004;Klose and Makeschin, 2005). Ram et al (2006a) found that the pH of mine spoil rose after lime-FA amendments during a field study.…”

An Investigation on principle biochemical components, photosynthetic pigments, nucleic acid and enzymatic activities of axenic culture of Scytonema sp. treated with two PAHs: Acenapthene and Fluoranthene

“…Other investigators (Burkhardt et al 1999, Riebesell et al 2000 demonstrated that the C/N ratio was influenced by a carbon enriched culture medium. In contrast, Chabbi & Rumpel (2004) considered that C/N ratios are a consequence of the presence of decomposing plant and/or microbial (including algae) residues. In this connection, our results regarding C/N ratios were slightly elevated relative to the control up to 50% aqueous diesel extract concentration.…”