Toxicity evaluation of the contaminated area of Crotone from biological indicators: a multispecies approach

Abstract

Contamination of terrestrial and aquatic ecosystems by toxic industrial waste has become a major issue in many countries. Of particular concern is the reuse of toxic hazardous waste in construction materials. This paper examined for the first time the chemical and radiation ecotoxicity of site-specific Technological Enhanced Naturally Occurring Radioactive Materials (TENORM) residues from phosphate processing industry in soil environmental matrices through bioindicators. The area under investigation was the former industrial district of Crotone (Calabria, Italy), recently included within the Sites of National Interest (SIN), comprising the 42 Italian national priority contaminated sites. Major biological exposure pathways considered were absorption and bioaccumulation. The marine bacterium Vibrio fischeri and the freshwater crustacean Daphnia magna were employed as aquatic bioindicators, while for the soil ecosystem, the seeds of Sorghum saccharatum and Lepidium sativum were used. Selection of test species aimed at assessing the toxicity of wastes in soil as well as in freshwater or marine systems. Results indicated V. fischeri as the most sensitive of all the species tested (5.56 g/L), while D. magna was found to be affected at 94.27 g/L. An overall inhibition was observed in seedling growth as compared to control at the highest concentration of the pollutants (100 g/L), while seed germination was not adversely affected by the pollutant. At this preliminary level, data indicated a potential risk for biodiversity of the area. In fact, the measured toxicity thresholds, even if above 100 mg/L, are comparable to concentrations of the toxicants spread all over the territory of Crotone.

Keywords: Anthropogenic radioactivity; Contaminated sites; Ecotoxicological bioassays; Phosphoric metasilicates; TENORM.

Fig. 1

a The location of the region around the City of Crotone and b the map of contaminated sites, showing significant differences in dose rates within the affected area (Procopio et al., 2019a)

Fig. 2

a Close-up picture of a road surface in Crotone showing a typical blue phosphate rock. b Severe potholes and slippage cracks in a major Crotone Road

Fig. 3

a Linear relationship between the function $\mathrm{\Gamma }$ and concentration and b between the % effect and concentration according to Eq. 2 for the pure phosphorite test sample after all exposure times (5, 15 and 30 min)

Fig. 4

V. fischeri bioluminescence inhibition (I_B%) after 30-min incubation time in various phosphorite residues

Fig. 5

Sorghum seeds in Petri dishes

Fig. 6

L. sativum in Petri dishes

Fig. 7

Mean percent germination over control of Sorghum and Lepidium seeds exposed to a 100 g/L phosphorite sample