Emerging pollutants have aroused an increasing concern due to their ubiquitous presence in the environment and harmful potential. Both emerging (e.g., pharmaceuticals and personal care products) and regulated organic pollutants pose a serious threat to water quality and their presence and spatial distribution are complicated to address as they can derive from several factors: distribution of point and diffuse sources, environmental conditions, hydrogeological features of the region and inherent properties of the considered contaminants. In this study, a ground and surface water monitoring campaign was conducted in the three main detritic groundwater bodies of an extensive and heavily modified river basin in order to draft an initial description of the occurrence and distribution of a wide range of organic contaminants. In total, 63 out of 185 target pollutants were detected. An attempt to understand the importance of different factors governing the distribution of some of the most frequently found pollutants was made. Antibiotics spatial distribution is potentially influenced by the hydrogeological functioning of the basin modified by hydraulic infrastructures (reflected by hydrochemistry and environmental tracers δ2H and δ18O), not directly related to the distribution of potential sources. The presence of other organic pollutants does not reflect an evident correlation with flow pathways. Differences in contaminant occurrence are potentially attributed to the way pollutants are released into the environment as well as physico-chemical properties.
<p>The anthropogenic organic contaminants contemplated in the environmental legislation, as well as those of emerging concern, threaten the quality of water resources to a degree that remains largely unknown. Contaminant exposure in the aquatic environment is a crucial element if a full understanding of the risk is pursued. There are still many uncertainties about the occurrence of organic contaminants and their behavior in the hydro(geo)logical media in large scale areas. The case study of the unconfined aquifer of the Granada Plain (approximately 200 km<sup>2</sup>) is presented here. Two groundwater and surface water monitoring campaigns were conducted (March 2017 and June 2018). Water samples were analysed for (i) 171 organic contaminants (e.g., pesticides, pharmaceuticals, drugs of abuse, PAHs); (ii) major and minor ions (Ca<sup>2+</sup>, Mg<sup>2+</sup>, Na<sup>+</sup>, K<sup>+</sup>, Cl<sup>-</sup>, SO<sub>4</sub><sup>2-</sup>, HCO<sub>3</sub><sup>-</sup>, NO<sub>3</sub><sup>-</sup>) and (iii) isotopes of the water molecule (&#948;<sup>18</sup>O, &#948;<sup>2</sup>H) and &#948;<sup>13</sup>C from the dissolved inorganic carbon. Additionally, <em>in situ</em> measurements of physico-chemical parameters (pH, temperature, electrical conductivity, redox potential and dissolved oxygen) were carried out. In total, 41 organic pollutants were detected, at least once: 17 pharmaceuticals or drugs of abuse, 21 pesticides or their metabolites and three PAHs. Statistical tests confirmed the significance of seasonal changes for some of these parameters (e.g., EC, Cl<sup>-</sup>, F<sup>-</sup>, &#948;<sup>18</sup>O, &#948;<sup>13</sup>C), revealing the influence from snowmelt water input on streams and the intensification of irrigation. In March 2017, the group of pesticides (largely represented by triazines) predominated, whereas the frequency of detection of pharmaceuticals increased substantially in June 2018. Based on the obtained results, a qualitative evaluation has been made to suggest four main factors affecting the spatial and seasonal variation of organic pollutants in the aquifer: (i) the variation of the unsaturated zone thickness; (ii) the river-groundwater hydraulic connection; (iii) the hydraulic gradient; and (iv) the anthropogenic factor determining the period of contaminant release throughout the year and wastewater management practices. The river-groundwater hydraulic connection can be especially important in the case of those contaminants whose main path of entry into the aquatic environment occurs through wastewater discharge into streams (i.e., pharmaceuticals).</p>
<p>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).</p> <p>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 (&#948;<sup>2</sup>H, &#948;<sup>18</sup>O and &#948;<sup>13</sup>C). Target organic contaminants included pharmaceuticals, personal care products, polyaromatic hydrocarbons, pesticides, flame retardants and plasticizers.</p> <p>The Fuente de Piedra lagoon is a hypersaline wetland located in an endorheic basin (150 km<sup>2</sup>) 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).&#160;</p> <p>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.</p>
<p>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.</p><p>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. Groundwater samples were collected and they were analyzed for (I) 185 organic contaminants and (II) water ions and stable isotopes (&#948;<sup>2</sup>H, &#948;<sup>18</sup>O and &#948;<sup>13</sup>C). Target organic contaminants included pharmaceuticals, personal care products, polyaromatic hydrocarbons, pesticides, flame retardants and plastizicers.</p><p>The Fuente de Piedra lagoon is a hypersaline wetland located in an endorheic basin (150 km<sup>2</sup>) 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).&#160;</p><p>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 physico-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.</p>
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