Effects of bituminous coal dust exposure on reproduction of Sinella curviseta (Collembola) and Eisenia fetida (Clitellata)

Abstract

Although coal extraction is an important source of income for several countries, including Colombia, there are problems associated with mining activities, especially in open-pit coal mines. One of these is the deposition of air-borne dust in areas surrounding open pit mines, the accumulation of which can result in changes to the biogeochemistry of surrounding soils, as well as potential impacts on soil organisms, which have an important role in the maintenance of soil physicochemical properties, and other functional attributes of soils.

This study aimed to determine the ecotoxicological impact of sub-chronic exposure to bituminous coal dust (diameter up to 38 μm) in two soil invertebrate model organisms - an earthworm: Eisenia fetida (Savigny, 1826); and a collembolan: Sinella curviseta Brook 1882 - in soil with relatively low concentrations of coal dust. A total of four concentrations (1 to 4 % w/w) and one negative control were tested in artificial soil. Organisms were assessed after 28 and 60 days. Results from E. fetida showed that despite the low mortality of adult earthworms, a significant reduction in the number of cocoons and juveniles was observed in treatments ≥2 %, after 28 days and 60 days. In addition, the average number of cocoons observed was significantly reduced even at the lowest concentration of coal dust (1 %) relative to controls.

Similarly, a substantial reduction in the number of S. curviseta adults was observed in all concentrations after 28 and 60 days, respectively. Our results suggest that both organisms are highly sensitive bioindicators of soil disturbance. These findings further suggest that soil organisms and foodwebs in natural substrates in the vicinity of open pit coal mines may be at risk of impacts due to exposure to coal dust with potential consequences for soil system function.