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Forest Fertilization with Wood Ash: Effect on the Distribution and Storage of Polycyclic Aromatic Hydrocarbons (PAHs) and Polychlorinated Biphenyls (PCBs)
Author(s) -
Bundt Maya,
Krauss Martin,
Blaser Peter,
Wilcke Wolfgang
Publication year - 2001
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2001.3041296x
Subject(s) - environmental chemistry , wood ash , chemistry , polycyclic aromatic hydrocarbon , environmental science , waste management , organic chemistry , engineering
Before wood ash can be safely used as a fertilizer in forests, possible negative effects such as input of organic contaminants or remobilization of contaminants already stored in the soil must be investigated. The objective of this study was to examine the effects of wood ash application on concentrations, storage, and distribution of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in a Swiss forest soil. In May 1998, we added 8 Mg wood ash ha −1 to a forest soil. We determined 20 PAHs and 14 PCBs in the organic layer, in the bulk mineral soil, and in soil material taken from preferential flow paths and from the matrix before and after the wood ash application. In the control plots, the concentrations of PAHs in the organic layer indicated moderate pollution (sum of 20 PAHs: 0.8–1.6 mg kg −1 ), but sum of PCB concentrations was high (21–48 μg kg −1 ). The wood ash had high concentrations of PAHs (sum of 20 PAHs: 16.8 mg kg −1 ), but low concentrations of PCBs (sum of 14 PCBs: 3.4 μg kg −1 ). The wood ash application increased the PAH concentrations in the organic horizons up to sixfold. In contrast, PCB concentrations did not change in the Oa horizon and decreased up to one third in the Oi and Oe horizons. The decrease was probably caused by the mobilization of stored PCBs because of the high pH of the wood ash. This probably results in a higher mobility of dissolved organic matter, acting as PCB carrier. In the mineral soil, the preferential flow paths of the A horizon contained more PAHs and PCBs (+20 ± 15% and +43 ± 60%, respectively) than the matrix. This was particularly true for higher molecular weight compounds (molecular weight > 200 g mol −1 ). Below 50 cm depth, concentrations of PAHs and PCBs were smaller in the preferential flow paths, suggesting that in deeper depths, processes acting as sinks dominated over inputs in the preferential flow paths.