Fate Hazardous elements in soils surrounding a coal-fired power plant complex

Proceedings of the 13th International UFZ-Deltares Conference on Sustainable Use and Management of Soil, Sediment and Water Resources - 9–12 June 2015 • Copenhagen, Denmark

A study was carried out in the vicinity of a Portuguese coal-fired power plant in order to determine the extent and degree of soils contamination that may be related to the dispersion of the atmospheric emissions from the this coal-fired power plant. Metals and soluble ions concentrations have been determined both in-situ and in soil samples collected at sites potentially affected by the stacks’ emissions. The analysis of trace elements was performed by means of X-ray fluorescence. The concentrations of twenty trace elements were determined: As, Ba, Ca, Co, Cu, Fe, Hg, K, Mn, Mo, Ni, Pb, Rb, S, Sb, Se, Sr, Ti, Zn, Zr, even though very few measurements were obtained for some of these elements in some specific areas around the power plant. The spatial distribution obtained by kriging in combination with the analysis of the data by Principal Component Analysis (PCA) showed three important situations in what concerns to metal concentration in soils and according to soil uses and geographic localization: the power plant (peak concentrations in the immediate area around the stacks), in the prevailing wind direction (from N-NW to E-SE and SE-S) and the area comprised between 6 and 20 km from the power plant (mostly agricultural and pasture areas). Considering that soil’s concentration for the studied elements may had its origin in the past atmospheric emissions from the coal-fired power plant and were accumulated in surface soils over the past decades, the height of the stacks and the dispersion by seasonal winds, could explain the observed enrichment of some elements in the area between the 6 and 20 km. However, some of the typical heavy metals associated with coal combustion emissions such as Cd, Cr, Hg and Ni were not significantly registered in the area under study and this may suggest the contribution from other industrial plants present in the region.