The Spatial Distribution of Characterized Fly-Ash Particles and Trace Metals in Lake Sediments and Catchment Mosses: Czech Republic

Abstract

As a part of the FLAME research project funded by the EU COPERNICUS programme (1994-1996) samples of surface sediments were taken from 31 man-made lakes and one natural lake in the Czech Republic. The sites differ considerably in their altitude, area, catchment, depth, retention time, trophic status, and in parameters of local air pollution. The samples were analysed for concentration of spheroidal carbonaceous particles (SCP, numbers per gram dry mass of sediment), a characteristic component of industrial fly-ash. The extracted carbonaceous particles were allocated according to the fuel-types combusted throughout Europe (coal, oil, brown coal, peat, oil shale) using particle chemistries derived by energy dispersive spectroscopy (EDS). Trace metals were also analysed in the surface sediments as were mosses sampled at the study sites. The main objectives of the study were (i) to look for factors determining SCP concentrations in surface sediments of lakes, with special emphasis on the distribution of large fossil-fuel combustion sources (ii) to compare fuel-type allocation of carbonaceous particles with combustion of these fuels within the country, (iii) to look for trends in spatial distribution of trace metals and (iv) to characterize the impact of airborne particles from these sources on environmental and human health. The SCP concentrations show little or no relation to air-pollution parameters on a small scale, although some large-scale effects are evident. A good relationship was, however, found to site characteristics such as altitude and lake area : catchment area. The reason, why this relationship is more apparent from our dataset than from any other study published so far, is likely to be based on the high variation in the physical parameters (altitude, lake and catchment area) of the sites under study. The distribution of particles attributed to brown coal combustion are in good agreement with the distribution of major air pollution sources across the country but the fraction of particles attributed to coal seems to be overestimated by the present technique. The distribution of trace metals in surface sediments are also in agreement with expected sources. The usefulness of SCP concentrations as indicators of stress to human and environmental health is briefly discussed.