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The southern rivers of Peru originate in the Andes Mountains and flow in a southwestern direction to the Pacific Ocean through one of the most hyper-arid regions of the world. During each sub-equatorial summer from December to February, rains and snow melt in the Andes increase the streamflow in these rivers, even as they pass through the 100 km arid zone to the ocean. This study quantified seasonal dynamics of 34 trace metal elements (TM) and other constituent concentrations in four southern river basins of Peru (Chili-Quilca, Tambo, Camana-Majes-Colca, and Ocoña) during 2019-2020. Consistent with previous studies, we observed that: (1) the river water in the southern basins had relatively high concentrations of B, As, Fe, Al, Mn, P, Pb and Ni, with As the most ubiquitous toxic TM in all the basins, often detected at concentrations surpassing Peruvian and USEPA regulated concentrations; and (2) basins with the most to least toxic TM contamination were the Tambo > Chili-Quilca > Camana-Majes-Colca > Ocoña. Seasonal streamflow strongly influenced the concentrations of twenty TM, with 15 TM (Al, Au, Ba, Cd, Co, Cu, Fe, Gd, Mn, Ni, P, Pb, Ti, Yb and Zr) consistently higher in the wet season, and with As, B, Ge, Li, and Pd higher in the dry season. Our results improve the understanding of seasonal variability and vulnerability in western Andes superficial water sources, which are highly influenced by both local geogenic and anthropogenic conditions. A Spanish translation of this paper is available in the online Supplementary Material.

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Biosolids and sewage effluent application to agricultural fields is becoming a win-win practice as both an economical waste management strategy and a source of nutrients and organic matter for plant growth. However, these organic wastes contain a variety of trace chemicals of environmental concern such as pharmaceuticals and personal care products (PPCPs), which may pose a risk to agricultural fields and ecosystems. This work aims to investigate the sorption of sitagliptin on four agricultural soils, evaluate the effects of biosolids and sewage effluent application, and elucidate the main sorption mechanism of the pharmaceutical on soils. The sorption study revealed that the sorption capacities of sitagliptin on different soils were positively related to the contents of soil organic matter and negatively associated with soil pH values. The application of biosolids and sewage effluent decreased the sorption capacity of sitagliptin, which may be attributed to the loading of dissolved organic matter derived from organic wastes. The Freundlich isotherm model demonstrated that the addition of biosolids from 0 to 100 % (W/W) consistently decreased the sorption affinity (Kf) of sitagliptin from 1.69 × 102 to 3.82 × 101 mg(1-n) Ln kg-1. Sewage application at 0, 10, 50, and 100 % (V/V) also reduced the Kf values from 1.69 × 102 to 9.17 × 101 mg(1-n) Ln kg-1. Attenuated Total Reflection (ATR)-Infrared (IR) spectroscopy analyses suggested that electrostatic interactions between carbonyl and amino groups of sitagliptin and the negatively charged soil surface are the main sorption mechanisms. In a co-solute system, the sorption affinity of sitagliptin on the soil decreased with increasing metformin concentrations, suggesting that competitive sorption may reduce the sorption capacity of individual contaminants in soil systems containing multiple PPCPs.

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A single workflow based on three approaches (target, suspected and non-target screening) using liquid chromatography coupled to quadrupole-time-of-flight mass spectrometry (LC-QTOF-MS) in data independent acquisition mode (DIA) was developed to assess the presence of emerging pollutants (EPs) in water and sediments from a Mediterranean River Basin. Identification of potential contaminants was based on mass accuracy, isotopic ratio pattern, theoretical fragmentation, and retention time using Waters UNIFI software. In the suspect screening against a library containing 2200 components, 68 contaminants were tentatively identified, 6 of which were confirmed and quantified with analytical standards. Non-target screening (NTS) required additional manual processing and the aid of an on-line database (ChemSpider) to tentatively identify compounds. Eprosartan, an antihypertensive drug not included in the library used for suspected screening, was confirmed and semi-quantified. The identification of Eprosartan proved the workflow to be functional for NTS. Target screening of 171 pesticides and 33 pharmaceuticals and personal care products (PPCPs) including the compounds confirmed using suspect (6) and non target (1) screening achieved monitoring of the most abundant contaminants from the head to the mouth of the Turia basin to establish their spatial distribution. QTOF-MS screening versatility with its high-resolution capability allows for a comprehensive assessment of EPs in the aquatic environment.

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A simple and environmentally friendly dispersive liquid-liquid microextraction (DLLME) method coupled with electrospray ionization liquid chromatography triple quadrupole mass spectrometry (LC-QqQ-MS/MS) was developed for the simultaneous determination of 17 synthetic and natural pyrethroids. A comparison of solid-phase extraction (SPE) versus DLLME for water samples and only "dilute and shoot" versus the additional extract cleanup by DLLME for sediment samples is reported. Chloroform was the extracting solvent in the DLLME technique for both water and sediment samples. Ultrasonic energy was applied to fully extract the analytes into fine droplets, providing high recoveries in short times. Method detection limits (MDLs) ranged from 0.12 to 0.62 ng L-1 and recoveries from 70 to 119% with RSD values 2-15% (n = 5) for water samples. In sediment samples, MDLs ranged from 0.50 to 2.50 ng g-1 and recoveries from 71 to 112% with RSDs 2-16% (n = 5). The proposed method showed a good linearity within the range of 10-500 ng mL-1, with coefficients of determination (R 2) higher than 0.99. Matrix effects were observed for most compounds in water and sediment (ME% < -10%). The proposed methodology was applied for the analysis of water and sediment samples from Albufera wetland and Turia River. Acrinathrin (48 ng g-1) and etofenprox (16 ng g-1) were detected in sediment samples. Graphical abstract Pyrethrins and pyrethroid determination in water and sediments by DLLME and LC-MS/MS.

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A new selective and sensitive liquid chromatography triple quadrupole mass spectrometry method was developed for simultaneous analysis of natural pyrethrins and synthetic pyrethroids residues in baby food. In this study, two sample preparation methods based on ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) and salting-out assisted liquid-liquid extraction (SALLE) were optimized, and then, compared regarding the performance criteria. Appropriate linearity in solvent and matrix-based calibrations, and suitable recoveries (75-120%) and precision (RSD values≤16%) were achieved for selected analytes by any of the sample preparation procedures. Both methods provided the analytical selectivity required for the monitoring of the insecticides in fruit-, cereal- and milk-based baby foods. SALLE, recognized by cost-effectiveness, and simple and fast execution, provided a lower enrichment factor, consequently, higher limits of quantification (LOQs) were obtained. Some of them too high to meet the strict legislation regarding baby food. Nonetheless, the combination of ultrasound and DLLME also resulted in a high sample throughput and environmental-friendly method, whose LOQs were lower than the default maximum residue limit (MRL) of 10µgkg-1 set by European Community for baby foods. In the commercial baby foods analyzed, cyhalothrin and etofenprox were detected in different samples, demonstrating the suitability of proposed method for baby food control.

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