Wood y ash from biofuel combustion plants is land lled commonly as a waste, but research of this material is needed because it may reduce future fertilizer requirements. We investigated the e ect of the ash application on potential changes in pH, nutrient, and potentially toxic element (in our case As, Cd, and Pb) content and mobility in soils. Wood y ash in doses up to 1% (w/w) was added to spring wheat (Triticum aestivum L.) grown in potentially toxic element-contaminated loam (Cambisol) and sandy clay loam (Fluvisol) soil material in 3-yr pot experiment. e potentially toxic element contents in soils exceeded the maximum permissible limits for Czech soils, but the plant availability was, thanks to ash addition, limited. e e ect of wood ash was greater in the Cambisol where Cd, Zn, and also Pb showed similar trends, and their content in plant decreased (Cd by 60%, Zn by 50%, and Pb by 45%), whereas the nutrient contents tended to increase in plants. Di erences were usually insigni cant (α = 0.05) in the Fluvisol between treatments, and Ca, Mg, and P contents were highest in the treatment without ash addition. e in uence of soil changes on element uptake and distribution within the aboveground plant biomass was also observed. ese ndings are an important step on providing evidence of the bene ts of using wood y ash as a fertilizer supplement, because potentially toxic element contents in wheat grown in contaminated soils with ash addition were low and decreased, whereas the concentrations of major nutrients increased.

No abstract

Both soil organic matter and sulfur (S) can reduce or even suppress mercury (Hg) mobility and bioavailability in soil. A batch incubation experiment was conducted with a Chernozem and a Luvisol artificially contaminated by 440 mg·kg−1 Hg showing wide differences in their physicochemical properties and available nutrients. The individual treatments were (i) digestate from the anaerobic fermentation of biowaste; (ii) fly ash from wood chip combustion; and (iii) ammonium sulfate, and every treatment was added with the same amount of S. The mobile Hg portion in Chernozem was highly reduced by adding digestate, even after 1 day of incubation, compared to control. Meanwhile, the outcome of these treatments was a decrease of mobile Hg forms as a function of incubation time whereas the contents of magnesium (Mg), potassium (K), iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), and phosphorus (P) were stimulated by the addition of digestate in both soils. The available calcium (Ca) contents were not affected by the digestate addition. The experiment proved digestate application as the efficient measure for fast reduction of mobile Hg at extremely contaminated soils. Moreover, the decrease of the mobile mercury portion was followed by improvement of the nutrient status of the soils.

Seven samples of the ash derived from biomass, representing both fly and bottom ash, were analysed for a wide spectrum of total and mobile contents of nutrient and potentially risk elements. Several techniques, X-ray fluorescence (XRF) spectrometry, instrumental neutron activation analysis (INAA), proton-induced gamma-ray emission (PIGE) and proton induced X-ray emission (PIXE), inductively coupled plasma-atomic emission spectrometry (ICP-OES), and flame atomic absorption spectrometry (F-AAS) were compared. The results showed fairly good agreement between the XRF and INAA results, where the correlation coefficients (r) varied between 0.96 and 0.98. Lower contents documenting insufficient dissolution of the ash samples in the applied acid mixture were observed for both ICP-OES and AAS. In this case, weaker correlation with the INAA results not exceeding r = 0.7 were obtained. Therefore, the sample decomposition step is a bottleneck of the accurate analysis of this type of materials. For the assessment of plant-available portions of the elements in the ash samples, the Mehlich III extraction procedure and the extraction with a 0.11 mol L−1 solution of CH3COOH were applied. The results showed relatively low mobility of the elements (especially micronutrients) in the ash samples regardless of their source and composition, suggesting limited immediate effect of direct ash application as a fertilizer.

Zemanová V., Trakal L., Ochecová P., Száková J., Pavlíková D. (2014) The results of the model experiment confirmed that the sorption from single-metal solution was more effective than sorption under multi-metal conditions, due to competitive effects. In all tested soils sorption of Cd, Cu and Zn decreased with the rate of other competitive metals; the Pb sorption was not affected by other competitive metals in solutions. Moreover, during multi-metal sorption, Zn was significantly desorbed in Cambisol. In general, sorptions of Cu, Pb and Zn were greater in uncontaminated soil compared to contaminated soils. Clear trend of impact of the contamination on Cd sorption was not observed. The results showed the sorption decreasing in order Chernozem > Fluvisol > Cambisol. The sorption was the greatest in uncontaminated soil with low mobility of studied metals.