Microscopy in addition to chemical analyses and ecotoxicological assays for the environmental hazard assessment of coal tar-polluted soils

International audienceChemical analysis of soils contaminated with coal tar indicated that most organic compounds, and particularly PAHs, were contained in coarser particles (> 200 μm). Microscopic observations of this fraction, carried out on polished sections, reported the presence of organic particles in addition to mineral particles. Some organic particles had a very low porosity, and their microstructure did not evolve during biotreatment. Alternatively, other organic particles had a large porosity composed of an interconnected pore network that was open to coal tar surface and thus in contact with soil water. Interconnected porosity seemed to increase during biotreatment in relation to a decrease in the amount of organic compounds. The amount of open porosity in contact with soil water was expected to increase the desorption rate of PAHs. Consequently, the environmental hazard could depend on the amount of open porosity in addition to chemical properties of organic particles, such as their concentration in PAHs. Thus, microscopy can be complementary to chemical analysis and ecotoxicological assays to assess the best strategy for remediation but also to follow the advancement of a biotreatment

Soil Sorption and Degradation Studies of Pharmaceutical Compounds Present in Recycled Wastewaters Based on Enantiomeric Fractionation

Wastewater (WW) reuse and biosolid application for vegetable crop culture is a practice applied worldwide. This strategy helps mitigate the pressure on water resources and improve the fertility of soil. Wastewater reuse is currently not included in chemical risk assessment, but its application has risk of potential accumulation of contaminants of emerging concern such as pharmaceutical active compounds (PhACs). In fact, this practice has caused the uptake of PhACs by plant and their subsequent entrance on the food chain. Residual quantities of contaminants may enter in soil, and they can be accumulated or percolated, consequently leading to contamination of groundwater. Herein, we report the main factors that play an important role on the accumulation of PhACs in soil after irrigation with treated wastewater. Limited data is actually available on the fate of PhACs in field studies because several processes are in competition for their dissipation including sorption and formation of non-extractable residues, leaching, as well as biotransformation. Consequently, an approach based on enantiomeric fractionation of chiral PhACs hasbeen suggested to discriminate between biotic and abiotic dissipation processes