Monitoring of phenols in natural waters and bottom sediments: preconcentration on a magnetic sorbent, GC–MS analysis, and weather observations

Abstract

Magnetic solid-phase extraction combined with GC–MS was applied to monitor phenols in river waters and bottom sediments. Annual and seasonal fluctuations in the phenol level, including their dependence on the flood pattern, rate of snowmelt, fallout of precipitation, and water and air temperature, were interpreted. The distribution of phenol concentrations in storage waters and bottom sediments was determined. A magnetic sorbent based on Fe3O4 nanoparticles and hypercrosslinked polystyrene is proposed for sorption of phenolic pollutants from aqueous media. The achieved enrichment factor (EF = 368–394) allows one to determine chloro- and nitrophenols, guaiacol, and phenol by GC–MS without preliminary derivatization. The limits of detection of phenols in real objects were 1.0–3.1 ng L–1. The developed method was applied to monitor waters and bottom sediments of the Voronezh Reservoir (Voronezh, Russia). Monitoring was performed from November 2015 till May 2019. Phenol, guaiacol, 2-chlorophenol, 3-chlorophenol, 4-chlorophenol, 2,4-dichlorophenol, 2,5-dichlorophenol, 2,4,5-trichlorophenol, and 2,4,6-trichlorophenol, as well as trace amounts of tetrachlorophenols and pentachlorophenol were found to be present in storage waters and bottom sediments. The maps of phenols distribution in the water reservoir at the time of their highest content in waters and bottom sediments were plotted. The highest concentrations of phenols in the reservoir were found to be at the time of extensive spring snowmelt and flood and storm rainfall. The maximum phenol concentrations in waters varied from 7 (for 2,5-dichlorophenol) to 232 ng L–1 (for 2,4-dichlorophenol), while those in bottom sediments were by 30–50% higher.