Search Results (3)

Contamination of marine ecosystems by pharmaceutically active compounds (PhACs) deserves more research since their environmental fate differs from that observed in freshwater systems. However, knowledge remains scarce, especially in semi-arid coastal regions of the Global South. This study investigates the occurrence and distribution of caffeine, carbamazepine, ciprofloxacin, and sulfamethoxazole in sediments from the La Paz lagoon, a coastal system in a semi-arid region of Mexico with inverse estuarine conditions. Samples of superficial sediments (0–5 cm depth) were collected from 18 sampling points distributed through the lagoon, encompassing sites heavily polluted by discharges of municipal sewage and 3 potentially pristine sites far from the urban and peri-urban zones. Also, a 25 cm length sediment core was taken and divided into 1 cm sub-samples to determine the deposition of target PhACs in the sediment bed through time. The extraction of the target PhACs was performed through the accelerated solvent extraction (ASE) technique and quantification was achieved using a validated HPLC-MS/MS analytical method. The concentration of caffeine, carbamazepine, ciprofloxacin, and sulfamethoxazole in superficial sediment oscillated in the range of 1 to 45 ng g⁻¹ (dry weight). The highest mass fraction of target PhACs was detected in sites impacted by wastewater discharges. The caffeine-to-carbamazepine ratio was determined for the first time in marine sediments impacted by wastewater discharges, resulting in values from 4.2 to 9.12. Analysis of the 25 cm length sediment core revealed a high dispersion of caffeine, which was attributed to high water solubility, while antibiotics were predominantly detected in the upper 20 cm of the core. Risk quotients were calculated, observing low risk for caffeine, carbamazepine, and ciprofloxacin, while sulfamethoxazole presented high risk in all the sampling points. PhACs are retained in superficial sediments from a lagoon impacted by wastewater discharges, and the level of impact depends on the properties of the compounds and the TOC content in sediments. Risk assessments should be performed in the future considering the combination of pharmaceuticals and byproducts in marine sediments. This research emphasizes the importance of sewage management in preserving marine ecosystems in semi-arid regions in the Global South. Full article

An optical crystalline silicon biosensor was developed for the detection of heavy metals in surface water, deep water, mollusks and sediment in the lagoon of La Paz, Baja California Sur, Mexico, to monitor the presence of heavy metals, the biosensor was built using self-assembled monolayers, the silicon supports were cut with a diameter of 0.5 cm × 0.5 cm, chemical modifications were made on the surface by adding KOH to obtain Si-OH groups, for the functionalization this was carried out by 3-aminopropyltrimethoxysilane to add NH₂ groups on the surface of the biosensor, the activation was with EDC/NHS as a crosslinking agent, Finally, the urease enzyme was immobilized on the surface of the biosensor in an orbital shaker at 100 rpm in PBS and proceeded to detect each of the concentrations of standard heavy metals methylmercury chloride, cadmium, lead, chromium oxide VI, arsenic oxide III and silver iodide at different concentrations. Subsequently, detection was performed on biological samples by taking the internal part of tissues placed in PBS under refrigeration and water samples were measured without treatment. The self-assembly and detection was characterized by FTIR in the region from 370 to 4000 cm⁻¹ taking the region from 1000 to 1200 cm⁻¹, 1500 to 1700 cm⁻¹ and from 2800 to 3100 cm⁻¹ as the most important regions for the principal component analysis, showing that in these regions the characteristic bonds of silicon are present, The functionalization showed the region of the primary and secondary amide and finally the detection was taken as the inhibition of the enzymatic activity, the principal component analysis showed the region where the detection of each heavy metal is performed and corroborates the results obtained in FTIR. Full article

Lake surface water temperature (LSWT) is a crucial water quality parameter that modulates many lake and reservoir processes. Therefore, it is necessary to monitor it from a long-term perspective. Over the last decades, many methods to retrieve LSWT fields from satellite imagery have been developed. This work aims to test, implement and automate six methods. These are performed in the Google Earth Engine (GEE) platform, using 30 m spatial resolution images from Landsat 7 and 8 satellites for 2000–2020. Automated methods deliver long-term time series. Series are then calibrated with in situ data. Two-dimensional (2D) × time data fields are built on the lakes with the calibration, and a subsequent LSWT climatology is derived. Our study area is two urban lagoons with areas smaller than two (2) km${}^2$ of the city of San Pedro de la Paz, South-Central Chile. The six methods describe the seasonal variation of LSWT (Willmott’s index of agreement > 0.91, $R^2$ > 0.67). The main difference between series is their bias. Thus, after a simple calibration, all series adequately describe the LSWT. We utilized the Pedro de la Paz lagoons to demonstrate the method’s utility. Our research demonstrates that these adjacent lagoons exhibit comparable LSWT spatial (15.5–17 ${}^{\circ }$C) and temporal (7–25 ${}^{\circ }$C) trends throughout the year. Differences in geographical pattern might result from the northern island’s heat impact and the existence of the Biobío river to the east. Our work represents an efficient alternative for obtaining LSWT in particular lakes and reservoirs, especially useful in medium and small-sized ones. Full article