Wind tunnel tests to estimate PM10 and PM2.5-emissions from complex substrates of open-cast strip mines in Germany

Open-cast lignite mines are sources of PM- emissions, caused by mining activities and wind erosion on the large bare deposition areas. PM10- and PM2.5-emissions of these technogenic materials have not been determined in detail so far, but are needed for emission cadastres or in dispersion models at the local scale In wind tunnel experiments substrates from the four active mines in Lower Lusatia in eastern Germany were investigated to estimate PM10- and PM2.5-emissions. The substrates include the cover layers and the lignite seams. Two experimental approaches were compared to relate the PM- emissions of the substrates to the main releasing mechanisms and substrate characteristics. The results show that lignite and lignite containing substrates emit distinctly higher amounts of PM10 and PM2.5 than mineral substrates, regardless of the releasing process. The estimated PM-emission potentials (PM-EP) ranged between 5 and 650 µg g−1 for PM10 and between 2 and 44 µg g−1 for PM2.5 and are correlated to the dry sieving fraction The highest PM- emissions per m2 occur together with the highest transport rates, although the materials themselves have low PM-EP. A distinct higher rate is emitted from lignite samples and substrates permeated with lignite. Wind erosion increases the PM10- emissions to 360 per cent and the PM2.5-emissions to 270 per cent of the PM-EP. The PM10- emissions of the mineral substrates are close to the potentials and heterogeneity of the materials has also an increasing effect.