Occurrence, distribution and behaviour of contaminants of emerging concern and regulated organic pollutants. Case study: the endorheic catchment of Fuente de Piedra Lagoon (Southern Spain)

Contaminants of Emerging Concern (CECs) and regulated organic pollutants pose a serious threat to water quality and their spatial distribution is challenging to assess as it can be driven by several factors (e.g., location of pollution sources, speciation, hydrophobicity, degradability, hydro(geo)logical features).

In the current work, we focus on the distribution of a wide range of regulated and non-regulated organic contaminants in groundwater of the Fuente de Piedra lagoon catchment, in Southern Spain. The collected groundwater samples were analyzed for (i) 185 organic contaminants, (ii) water ions and (iii) stable isotopes (δ²H, δ¹⁸O and δ¹³C). Target organic contaminants included pharmaceuticals, personal care products, polyaromatic hydrocarbons, pesticides, flame retardants and plasticizers.

The Fuente de Piedra lagoon is a hypersaline wetland located in an endorheic basin (150 km²) in which three main aquifer types, with an hydraulic connection, can be distinguished: (i) unconfined carbonate aquifers with low mineralized water corresponding to two mountain ranges; (ii) an unconfined porous aquifer formed by Quaternary and Miocene deposits, more exposed to pollution from anthropogenic activities; and (iii) a karstic-type confined aquifer developed in a massive accumulation of evaporites and gypsum (Upper Triassic). 

In total, 32 organic contaminants were detected, at least once. An attempt to evaluate the importance of the different factors affecting the spatial distribution of the organic contaminants have been conducted. Attention has been paid to the main physical-chemical properties of the pollutants (hydrophobicity and speciation), distribution of pollution sources and anthropogenic pressures in the area (including water management practices) and hydrogeological characteristics of the different aquifers. A geochemical model has been built to characterize water mixing processes in order to better understand transport and fate of these organic contaminants. The results obtained suggest that some contaminants may accumulate and be more present in sampling points more affected by longer residence water fluxes.