Characterization of anthropogenic impacts in Mediterranean intermittent rivers with chemical, ecological and hydrological indicators.

Water scarcity in the Mediterranean area has increased the number of intermittent rivers, whose flow ceases either occasionally or totally. Key elements to characterize their dynamics are water quality, hydrological, and ecological status, when wastewater effluents dominate flow. Regarding water quality, pharmaceuticals are major pollutants, and serve as indicators of wastewater presence. Intermittent rivers are biodiversity hotspots where their hydrological regime may suffer alterations associated with wastewater effluents, making them harder to characterize than perennial streams. This study aimed to integratively characterize intermittent rivers through chemical, ecological and hydrological status calculating respective indices in twenty Mediterranean intermittent wastewater-impacted rivers located in Spain, France, Italy, Algeria and Tunisia. Pharmaceuticals were used as indicators assessing their frequency of PNEC exceedance and detection; while two ecological indicators and one hydrological indicator were used to evaluate wastewater stress on catchments. All indicators displayed a noticeable decline from upper to lower parts of the rivers, proving the effect of anthropogenic stressors on the aquatic environment. The Tunisian catchment displayed the most compromised conditions across all indicators, and the Algerian site even though low concentrations were detected, five compounds exceeded PNEC thresholds. This highlights the need for increased dedication and the adoption of water pollution solutions.

HRMS-Targeted-DIA methodology for quantification of wastewater-borne pollutants in surface water.

A robust method was developed for the quantification of popular and highly occurrence contaminants of emerging concern from wastewater treatment plant effluents and is explained in detail. A homemade multi-layered and multi-sorbent solid phase extraction (SPE) cartridge was used to cover the wide range of polarities of the selected contaminants. A non-discriminant elution protocol was also applied. Liquid chromatography coupled to a high-resolution mass spectrometer (HRMS) Q-Exactive Orbitrap system was used for the separation and detection of the contaminants. A targeted data independent acquisition (DIA) mode with an inclusion list with the exact mass, retention time window and collision energy was tried for the first time obtaining good sensitivity, selectivity and high quality MS2 product ions.•116 compounds of a wide-scope of polarities and physic-chemical properties were validated using a surface water pool matrix.•SPE followed by LC-HRMS with a targeted DIA was used for the method validation at three concentration levels 5, 50, 500 µg l-1 in extract.•Good recoveries were obtained between 70 and 120% for the majority of the selected contaminants. Matrix effect, precision, and linearity were also evaluated and results proved the suitability for the method application.