Effect of Soil Treatment with Silver and Gold Nanoparticles on the Accumulation of Ag, Au, and Other Elements in Earthworm Eisenia fetida and Their Vitality

The effect of treatment of the Californian earthworm Eisenia fetida with preparations containing silver (Ag; in the form of either nanoparticles (AgNPs) or cations (AgNO3 solution)) and gold (Au; in the form of nanoparticles (AuNPs)) on its vitality was studied in a laboratory experiment for 12, 48, and 158 h. After the observations were completed, the total elemen content was analysed after exposure to individual preparations applied to the soil. Earthworms and the soil in which they were grown were analysed. Measurements were performed using the inductively coupled plasma mass spectrometry technique, with prior mineralisation of earthworms and soil samples. The results of quantitative studies showed a several-fold increase in Ag content in earthworms exposed to preparations containing Ag compared to the control group. Significantly higher contents of K, Na, P, Mg, and Si were also found in earthworms exposed to Ag and Au compared to the control group. Despite exposure to AuNPs, no increase in the concentration of this element was observed in the earthworms. The analysis also included other elements: Li, Al, Ca, Ti, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Mo, Ag, Cd, Ba, Au, Hg, Tl, and Pb. The initial analysis did not show any significant differences in the concentrations of these elements in earthworms exposed to individual preparations compared to the control. The high level of elements classified as toxic to earthworms, including As, Cd, and Pb, is noteworthy, but the concentrations of these elements were not dependent on the use of any of the preparations. Based on a visual inspection of live individuals, we could not confirm the reduced vitality of earthworms exposed to individual preparations compared to the control. In contrast, individual populations retained full vitality after exposure and reproduced.