Sequential extraction partitioning of trace and nutrient elements in ashes from biomass firing district heating plantsM. Šyc, M. Tošnarová, J. Hrma, M. Pohořelý, K. Svoboda and M. PunčochářE3S Web of Conferences, 1 (2013) 20011DOI: https://doi.org/10.1051/e3sconf/20130120011