Changes In Soil Chemical Composition Caused By Self-Heating Of A Coal-Waste Dump

The paper presents soil features and chemical composition in a self-heating coal-waste dump. The investigations were carried out in the Upper Silesian Coal Basin. A fire zone in which the soil temperature exceeded 50 degrees C was selected for our study. Soil analyses were carried out for three grain sizes - d > 1 mm, 0.063 mm < d <= 1 mm, and d <= 0.063 mm - enabling identification of the diversity of the chemical composition in soil fractions. The highest concentration of heavy metals is represented by Mn (212-6972 mg kg(-1)), Zn (127-3283 mg kg(-1)), Pb (33.6-1344.7 mg kg(-1)), Cu (38.9-101.4 mg kg(-1)), and major elements by Fe (14,300-117,400 mg kg(-1)) and Ca (900-63,600 mg kg(-1)). Soil chemistry showed variations within individual studied sites. The soil reaction ranges from acidic (4.3 in KCl and 5.26 in H2O) to moderate alkaline (7.96 in H2O and 7.31 in KCl), whereas TOC ranges from 1.21% to 14.60% and TN from 0.023% to 0.291%. The distribution of n-alkanes clearly showed a low degree of transformation of organic matter and characteristic high values of Pr/Ph ratio for humic coals and coal waste in the region. Grains with diameters greater than 1 mm exhibited completely different features than those of fractions smaller than or equal to 1 mm. High organic carbon content (14.60) was detected in the samples along with PAHs. The influence of fire on the chemical composition of all samples was identified using geochemical indicators. PCA analysis showed that the values of the variables were more closely correlated in finer grains than in the coarsest fraction.