Fate of parabens and 4-hydroxybenzoic acid in aquifer materials columns during step experiments with fresh and sea waters

Abstract

Please cite this article as: López-Ortiz, C.M., Boluda-Botella, N., Prats-Rico, D., Sentana-Gadea, I., Fate of parabens and 4-hydroxybenzoic acid in aquifer materials columns during step experiments with fresh and sea waters, Journal of Hydrology (2017), doi: https://doi. AbstractCoastal areas submitted to seawater intrusion and with discharges from urban and industrial wastewaters, municipal landfill leachates, rivers, recreational waters and other sources are sensitive to be polluted with parabens. Understanding the fate of these compounds in environmental studies, it requires previously the knowledge of the reactive processes in controlled conditions. In this research, laboratory columns experiments were carried out with a group of parabens (methyl-, ethyl-, propyl-and butylparaben) and their main degradation compound (4-hydroxybenzoic acid) to study mainly the dynamic sorption processes in different aquifer materials (100% sand and heterogeneous: 81% sand, 9% silt and 10% clay) and with fresh and sea waters, the end members of seawater intrusions. To the column hydrodynamic characterization, tracer assays with increase and decrease of salinity were performed, to obtain the mean residence time of each column and other transport parameters which allow us to compare parabens´ sorption in different conditions. The results of the adsorption and desorption of parabens in the sand column demonstrated be fast and simultaneous, with a short delay and without influence of the water salinity. Very different results were found in the column experiments with heterogeneous material, where the presence of clay and organic matter increase the time of adsorption/desorption as the length of the alkyl chain paraben increased, according with their hydrophobicity. It should be noted that despite the quick desorption of the major quantities of parabens, the elution of their trace concentrations was very slow (for the seawater, the buthylparaben required a dimensionless time of 800). Planning the restoration of a coastal aquifer with freshwater, and in the conditions of the studied sand column experiment, it will need a dimensionless time of 160. However, it is necessary to take into account that the studied parabens and 4-hydroxybenzoic acid are biodegradable substances, as can be seen in long term experiments, when bacterial proliferation could occur, despite starting the experiment under sterile conditions.

Emergent contaminants in spring rivers and their relation to the benthic macroinvertebrates

“…However, the concentrations in the aqueous matrix are above the concentrations found in non-target areas for supply in other countries. The sediments act as a sink for parabens, due the lipophilic nature of these compounds, and the low concentrations found suggest that the presence of these compounds in the environment is recent (Peng et al, 2017;López-Ortiz et al, 2018) As for the sterols, the concentrations of sitosterol were generally much higher than the concentrations of coprostanol, except in the Extravasor Channel (CE), where the concentrations found were similar (Table 3). Gonzales-Oreja and Saiz-Salinas (1998) suggested in their study that values above 500 ng g -1 of coprostanol in the sediment indicate contamination by sewage, since this sterol is present in human faeces in concentrations 10 times higher than the others (Leeming et al, 2015;Bujagić et al, 2016;Nakagawa et al, 2019).…”