Occurrence and spatial distribution of emerging contaminants in the unsaturated zone. Case study: Guadalete River basin (Cadiz, Spain)
Abstract
Irrigation with reclaimed water is becoming a common practice in arid- and semi-arid regions as a consequence
of structural water resource scarcity. This practice can lead to contamination of the vadose zone
if sewage-derived contaminants are not removed properly. In the current work, we have characterized
soils from the Guadalete River basin (SW Spain), which are often irrigated with reclaimed water from
a nearby wastewater treatment plant and amended using sludge. Physico-chemical, mineralogical and
hydraulic properties were measured in soil samples from this area (from surface up to 2 m depth).
Emerging contaminants (synthetic surfactants and pharmaceutically active compounds, or PhACs) were
also determined. Synthetic surfactants, widely used in personal care products (PCPs), were found in a
wide range of concentrations: 73–1300 lg kg1 for linear alkylbenzene sulfonates (LAS), 120–
496 lg kg1 for alkyl ethoxysulfates (AES), 19–1090 lg kg1 for alcohol polyethoxylates (AEOs), and
155–280 lg kg1 for nonylphenol polyethoxylates (NPEOs). The presence of surfactant homologues with
longer alkyl chains was predominant due to their sorption capacity. A positive correlation was found
between LAS and AEOs and soil organic carbon and clay content, respectively. Out of 64 PhACs analyzed,
only 7 were detected occasionally (diclofenac, metoprolol, fenofibrate, carbamazepine, clarithromycin,
famotidine and hydrochlorothiazide), always at very low concentrations (from 0.1 to 1.3 lg kg1).
Domains
Earth Sciences
Origin : Files produced by the author(s)