Diversidad de ninfas de Leptohyphidae (Ephemeroptera) en el río Quenane-Quenanito, piedemonte llanero colombiano / Diversity of Leptohyphidae (Ephemeroptera) nymphs in the Quenane-Quenanito river, Colombian plain foothills

Resumen Introducción: Varias presiones antrópicas sufren los ecosistemas acuáticos del piedemonte llanero en Colombia. La respuesta a estresores ambientales aún se desconoce en organismos bioindicadores como Leptohyphidae. Objetivo: Determinar la diversidad de ninfas de Leptohyphidae del río Quenane-Quenanito, en dos periodos hidrológicos contrastantes y su relación con algunas variables fisicoquímicas. Métodos: En diciembre (2014) y febrero (2015) se recolectaron organismos con red Surber en seis estaciones a lo largo del río. Se analizó la diversidad alfa y beta y se aplicó análisis de redundancia y modelos lineales generalizados con el fin de establecer la relación entre los taxones y las variables ambientales. Resultados: Se identificaron 369 organismos pertenecientes a cuatro géneros (Amanahyphes, Traverhyphes, Tricorythopsis y Tricorythodes), dos especies y ocho morfoespecies. Se reporta por primera vez para el departamento del Meta Amanahyphes saguassu. Se registró la mayor diversidad de ninfas en la transición a la sequía y la mayor abundancia en sequía. La diversidad beta señaló que la configuración del ensamblaje cambia a nivel espacial y temporal. Conclusiones: Los organismos de Leptohyphidae prefieren hábitats de corrientes, particularmente en el periodo de sequía, donde hallan alimento (hojarasca, detritos) y refugio para establecerse exitosamente; actividades antrópicas como la urbanización afectan notablemente la diversidad. La alta diversidad registrada en este pequeño río de piedemonte llanero refleja la necesidad de incrementar este tipo de trabajos y esfuerzos de recolección de material de estudio en la región.

Abstract Introduction: Various anthropic pressures affect the aquatic ecosystems of the foothills of Colombia. The response to environmental stressors is still unknown in bioindicator organisms such as Leptohyphidae. Objective: To determine the diversity of Leptohyphidae nymphs of the Quenane-Quenanito river, in two contrasting hydrological periods and its relationship with some physicochemical variables. Methods: In December (2014) and February (2015), organisms were collected with a Surber net at six stations along the current. Alpha and beta diversity was analyzed and redundancy analysis and generalized linear model were applied to establish the relationship between taxa and environmental variables. Results: Were identified 369 organisms belonging to four genera (Amanahyphes, Traverhyphes, Tricorythopsis, and Tricorythodes), two species, and eight morphospecies. Amanahyphes saguassu is reported for the first time for the Meta department. High diversity of Leptohyphidae nymphs was recorded in the transition to drought season and greater abundance in drought. Beta diversity indicated that the configuration of the assemblage changes spatially and temporally. Conclusions: Leptohyphidae organisms prefer fast habitats, particularly in the dry period where they find food (leaf litter, detritus) and shelter to establish themselves successfully; anthropic activities such as urbanization notably affect diversity. The high diversity recorded in this small river in the foothills of the plains reflects the need to increase this type of works and collection efforts of study material in the region.

Poultry slaughterhouse wastewater as a source of bacterial antimicrobial resistance.

Slaughterhouses produce huge volumes of effluents throughout the production chain that, when discharged untreated into bodies of water, can become a source of environmental contamination. This is particularly worrisome if these effluents are used for irrigation since they increase contamination levels and spread pathogens and resistance determinants to humans and animals. Therefore, in this study, we assessed antimicrobial resistance in bacteria isolated from inlet water, equalization wastewater tanks, treatment plant wastewater, and treated wastewater in slaughterhouse facilities in Rio de Janeiro, Brazil. Four samples were collected at each of the collection points, between June 2021 and July 2022. Following bacterial isolation and identification, the samples were analyzed for antimicrobial resistance using the disk diffusion method to test aminoglycoside, beta-lactam, and fluoroquinolone antimicrobials. A total of 229 bacteria were isolated, with 74 isolates selected from the genera Citrobacter (12), Enterobacter (14), Klebsiella (35), Serratia (5), and Pseudomonas (8). Inlet water had the lowest number of isolates and was the only point with gentamicin-resistant isolates. Raw effluent from the equalization tank showed the highest number of isolated bacteria and resistance levels, followed by treated wastewater and the treatment plant. Across all samples, a high rate of cefoxitin-resistance was observed among the isolated bacteria. Klebsiella pneumoniae stood out as the species that demonstrated the greatest resistance to a variety of antimicrobials. These results highlight the importance of water quality monitoring in mitigating public health and environmental risks and high antimicrobial resistance levels.

Levels of Potentially Toxic and Essential Elements in Water and Estimation of Human Health Risks in a River Located at the Interface of Brazilian Savanna and Amazon Biomes (Tocantins River).

The Tocantins-Araguaia basin is one of South America's largest river systems, across three Brazilian states (Maranhão, Tocantins, and Pará), within the Legal Amazon region. Despite draining extensive Cerrado savanna and rainforest ecosystems, it has suffered significant degradation, notably in the past 40 years. Human activities, including agricultural expansion, deforestation, and the introduction of non-native species, have worsened the environmental damage, which is alarming since many residents and villages along the middle Tocantins River rely on it for water supply, recreation, and fishing. This study assessed the concentration of potentially toxic and essential elements in water samples from four sampling sites distributed along the middle Tocantins River. The monitoring occurred throughout 2023, involving the measurement of parameters both on-site and in the laboratory. Water quality and its health implications were evaluated using the Weighted Arithmetic Water Quality Index (WAWQI), the Water Quality Index (WQI), and the health risk assessment index. The levels of aluminum, copper, iron, magnesium, and selenium exceeded legal standards. Seasonal fluctuations indicate a complex dynamic influenced by climatic or seasonal factors, with February showing the highest values. Site P1, located in urban areas, exhibited elevated mean concentrations for conductivity, total dissolved solids (TDS), and chlorophyll, indicating the need for continuous monitoring. The nitrogen concentrations at P1 raise concerns regarding drinking water quality, which is a concern for the region's residents who use untreated river water. Despite seasonal variations in element concentrations, the overall WAWQI categorized all sections as "Excellent," and the WQI rated as "Good." Human health risk assessments detected no risks, but continuous monitoring and interventions are crucial for sustained water quality improvement.

Sediment analysis and water quality assessment in the Pixquiac basin: drinking water supply of Xalapa city (Veracruz, Mexico).

Fluvial sediment analysis and water quality assessment are useful to identify anthropic and natural sources of pollution in rivers. Currently, there is a lack of information about water quality in the Pixquiac basin (Veracruz state, Mexico), and this scarcity of data prevents authorities to take adequate measures to protect water resources. The basin is a crucial territory for Xalapa, the capital city of Veracruz state, as it gets 39% of its drinkable water from it. This research analyzed 10 physicochemical parameters and 12 metal concentrations in various rivers and sources during two seasons. Dissolved metals presented average concentrations (µg/L): Al (456.25) > Fe (199.4) > Mn (16.86) > Ba (13.8) > Zn (7.6) > Cu (1.03) > Pb (0.27) > As (0.12) > Ni (0.118) (Cd, Cr and Hg undetectable). Metals in sediment recorded average concentrations (ppm): Fe (38575) > Al (38425) > Mn (460) > Ba (206.2) > Zn (65.1) > Cr (29.8) > Ni (20.9) > Cu (16.4) > Pb (4.8) > As (2.1) (Cd and Hg undetectable). During the rainy season, Water Quality Index (WAWQI) classified stations P17 and P18's water as "unsuitable for drinking" with values of 110.4 and 117.6. Enrichment factor (EF) recorded a "moderate enrichment" of Pb in sediment in P24. Pollution was mainly explained by wastewater discharges in rivers but also because of erosion and rainfall events. Statistical analysis presented strong relationships between trace and major metals which could explain a common natural origin for metals in water and sediment: rock lixiviation.

Anthropogenic land uses lead to changes in limnological variables in Neotropical streams.

Streams are vulnerable to anthropogenic impacts, such as changes in land use, which reflect on water quality and can be evaluated by abiotic variables. In this context, the aims were to compare the abiotic values recorded in streams of different land use categories with the limits established by National legislation, and to analyze changes in abiotic variables in response to different land use impacts. Thus, 17 streams located in southern Brazil were sampled and grouped into urban, rural, and protected areas (PA) categories. The results showed the major impacts in urban streams. However, some variables in rural streams and PA also exceeded local legislation limits. Conductivity, total dissolved solids, salinity, ammoniacal nitrogen and coliforms were significantly higher in the urban streams. Contrary to expectations, the highest levels of manganese were found in PA streams. The relationship between abiotic variables and land uses suggests possible contamination by sewage in urban streams and by pesticides in rural streams. The abiotic similarity between rural and PA streams indicates that the conservation of these water bodies is ineffective. We suggest the monitoring of these environments and measures to mitigate the impacts to seek the restoration of ecosystem services and the well-being of human populations.

Evaluation of low-cost sensors to integrate in a water quality monitor for real-time measurements.

Low-cost sensors integrated with the Internet of Things can enable real-time environmental monitoring networks and provide valuable water quality information to the public. However, the accuracy and precision of the values measured by the sensors are critical for widespread adoption. In this study, 19 different low-cost sensors, commonly found in the literature, from four different manufacturers are tested for measuring five water quality parameters: pH, dissolved oxygen, oxidation-reduction potential, turbidity, and temperature. The low-cost sensors are evaluated for each parameter by calculating the error and precision compared to a typical multiparameter probe assumed as a reference. The comparison was performed in a controlled environment with simultaneous measurements of real water samples. The relative error ranged from - 0.33 to 33.77%, and most of them were ≤ 5%. The pH and temperature were the ones with the most accurate results. In conclusion, low-cost sensors are a complementary alternative to quickly detect changes in water quality parameters. Further studies are necessary to establish a guideline for the operation and maintenance of low-cost sensors.

Efficient trihalomethane quantification in drinking water for minimally-equipped water treatment plants labs.

Chlorine is a common disinfectant used in water treatment. However, its reaction with organic matter can lead to the formation of harmful byproducts, such as trihalomethanes (THMs), which are potentially carcinogenic. To address this issue, the aim of this work was to enhance a colorimetric method capable of quantifying THMs in drinking water through UV/Vis Spectrophotometry, using cost-effective equipment, and validate this methodology for the first time according to established validation protocols. The method's innovation involved replacing the solvent pentane with the more common hexane, along with adjusting the heating ramp, elucidating the mechanisms involved in the process. This method involves the reaction between THMs, pyridine, and NaOH to produce a colored compound, which is then monitored through molecular absorption spectroscopy in the visible region. The method was thoroughly validated, achieving a limit of detection of 13.41 µg L-1 and a limit of quantification of 40.65 µg L-1. Recovery assays ranged from 86.1 % to 90.7 %, demonstrating high accuracy. The quality of the linear fit for the analytical curve exceeded R2 > 0.98. The method was applied to real samples, revealing concentrations ranging from 13.58 to 55.46 µg L-1, all way below the legal limit in Brazil (Maximum Contaminant Levels (MCL) = 100 µg L-1). This cost-effective and straightforward method is suitable for integration into water treatment plant laboratories.

Exploring the nexus between water quality and land use/land cover change in an urban watershed in Uruguay: a machine learning approach.

The expansion of urban areas contributes to the growth of impervious surfaces, leading to increased pollution and altering the configuration, composition, and context of land covers. This study employed machine learning methods (partial least square regressor and the Shapley Additive exPlanations) to explore the intricate relationships between urban expansion, land cover changes, and water quality in a watershed with a park and lake. To address this, we first evaluated the spatio-temporal variation of some physicochemical and microbiological water quality variables, generated yearly land cover maps of the basin adopting several machine learning classifiers, and computed the most suitable landscape metrics that better represent the land cover. The main results highlighted the importance of spatial arrangement and the size of the contributing watershed on water quality. Compact urban forms appeared to mitigate the impact on pollutants. This research provides valuable insights into the intricate relationship between landscape characteristics and water quality dynamics, informing targeted watershed management strategies aimed at mitigating pollution and ensuring the health and resilience of aquatic ecosystems.

Influence of hydroclimatic conditions and anthropogenic activities on the water quality of a floodplain lake (Argentina) during a warm season.

Contamination of water bodies, associated with urbanization, agricultural, and industrial activities, is a serious environmental challenge, with particular concern about microbial pollution due to its public health implications. This study is aimed at evaluating the spatial and temporal variations in the microbiological and physicochemical quality of a floodplain lake used for recreational purposes, whose watershed has been disturbed by diverse anthropogenic activities. The results showed that, while the spatial variation of water quality principally depends on the basin characteristics, temporal variation of water quality depends on land uses, hydrological conditions, and climatic conditions. Rainfall and rising water level intensified the influence of land use on the water quality by increasing concentrations of Escherichia coli, thermotolerant coliforms, and organic matter and decreasing dissolved oxygen. Thus, the residents and tourists are potentially exposed to microbiological risks given that it exceeds the international standards suggested for recreational waters on some occasions. It would be advisable to improve routine bathing water monitoring and management to preserve the health of the inhabitants and limit the recreational use of the water body in the days following heavy rainfall as well as during the beginning of the increase in the hydrometric level.

A multi-evidence approach in an Amazonian river based on land use, water quality, histopathological effects and habitat selection behavior in fish.

The Amazon rivers constitute the largest river basin in the world, with a high level of biodiversity. The Tocantins River is one of the most important rivers in this region, which has been impacted by different land uses. The objective of this study was to carry out a multi-evidence analysis focusing on the water quality of the Tocantins River, close to the municipality of Marabá-PA. We analyzed forest cover and water quality and, using the model organism Danio rerio, performed toxicity tests for histopathological effects, as well as the habitat selection approach by exposing fish to different river water samples in a multi-compartment device. The results showed that the studied area has already lost almost 30% of its forests in recent decades. Regarding water quality, the upstream (C1) and downstream (C5) points are the least impacted. On the other hand, the other points (C2-C4), closer to the city, greater input of pollutants was detected. Fish exposed to water samples from the most impacted sites showed several oedemas and hyperplastic cells in the gills. Regarding habitat selection behavior, there was a marked avoidance by samples with the highest contamination load. The results of this study lead to the understanding of the potential negative effects of human activities on local Amazonian biodiversity, since the potential toxicity of the environment, in conjunction with changes in the habitat selection process, could lead to a decline in populations of aquatic organisms, altering the environmental balance.

Microplastic pollution responses to spatial and seasonal variations and water level management in a polymictic tropical reservoir (São Paulo, Brazil).

We assessed microplastic (µP) pollution in water and sediment samples during the dry and rainy season (October/2018 and March/2019, respectively) from the Guarapiranga Reservoir in the Metropolitan Region of São Paulo, Brazil, which provides drinking water for up to 5.2 million people. The concentration of mPs varied spatially and seasonally, with the higher concentrations observed near the urbanized areas and during the dry season. Water column concentrations ranged from 150 to 3100 particles/m3 and 0.07-25.05 mm3 plastic/m3 water during the dry season, and 70-7900 particles/m3 and 0.06-4.57 mm3 plastic/m3 water during the rainy season. Sediment samples were collected only during the rainy season, with concentrations ranging from 210 to 22,999 particles/kg dry weight and 0.15-111.46 mm3/kg dry weight. The particle size distribution exhibited seasonal variation, with µPs >1 mm predominating during the dry season, constituting 60-75% of all particles. In terms of quantity, fibers accounted for the majority of microplastics, comprising 55-95% during the dry season and 70-92% during the rainy season. However, when considering particle volume, irregular particles dominated in some samples, accounting for up to 95% of the total amount. The predominant colors of microplastics were white/crystal, black, and blue, with the main compositions identified as polypropylene (PP) and polyethylene terephthalate (PET), suggesting the influence of untreated domestic sewage discharge. Additionally, some additives were detected, including the pigments Fast RED ITR and phthalocyanine blue. The management of reservoir water levels appears to influence the quantity of µPs in the water column. As the water level increases up to 90% of the reservoir capacity during the rainy season, the amount of µPs in the water decreases, despite the higher influx of particles resulting from surface runoff caused by rainy conditions. This suggests a "dilution" effect combined to the polymictic mixing hydrodynamics. Our results may contribute to the creation and improvement of monitoring programs regarding mP pollution and to the adoption of specific public policies, which are still lacking in legislation.

Reduction of Helicobacter pylori cells in rural water supply using slow sand filtration.

Helicobacter pylori is a microorganism that infects 60% of the population and is considered the main cause of atrophic gastritis, gastric and duodenal ulcers, and gastric cancer. Different emerging pathogens have been found in drinking water and their presence is considered to be an important public health problem. For this reason, it is necessary to carry out the validation of reliable technologies for this type of pathogens and evaluate their performance. This paper reports, for the first time, H. pylori reduction in a drinking water pilot plant of two slow sand filters (SSF). Inlet water was taken from a gravel filtration system of a rural water supply in Colombia and then inoculated with viable cells of H. pylori. By determining the Genomic Units (GU) through quantitative Polymerase Chain Reaction (qPCR), the concentration of GU/sample was measured. In the inlet water amplification for SSF1 and SSF2 were 5.13 × 102 ± 4.48 × 102 and 6.59 × 102 ± 7.32 × 102, respectively, while for the treated water they were 7.0 ± 5.6 and 2.05 × 101 ± 2.9 × 101 GU/sample for SSF1 and SSF2, respectively. The SSF pilot plant reached up to 3 log reduction units of H. pylori; therefore, since there is not an H. pylori contamination indicator and its periodic monitoring is financially complicated, the SSF could guarantee the drinking water quality necessity that exists in rural areas and small municipalities in developing countries, where infection rates and prevalence of this pathogen are high.

Diel and seasonal mixing patterns and water quality dynamics in a multipurpose tropical semiarid reservoir.

Eutrophication has become a recurrent concern in reservoirs worldwide. This problem is intensified in tropical semiarid regions, where the reservoirs have high seasonal and annual variability of water level and volume. Therefore, an extensive understanding of the diel variation of water quality key-parameters can help improve management of such reservoirs. This study focuses on Castanhão reservoir with the largest multipurpose dam in the Brazilian semiarid. Its main water uses are irrigation, fish farming, and human supply. The reservoir faced a decline in water quality due to a prolonged drought period. While previous research has predominantly emphasized the seasonal dynamics of thermal and chemical stratification, our investigation provides diel assessments of multiple water quality parameters, including nutrient concentrations and phytoplankton abundance. Our primary objective is to compare seasonal and diel variations in stratification and nutrient distribution within the reservoir. Key findings reveal a diel cycle of thermal stratification, primarily during dry season, driven by higher wind speeds. This is corroborated by a significant negative correlation between wind speed and the relative water column stability index. In contrast, during the rainy season, the reservoir experiences continuous thermal stratification due to inflowing water being warmer than the reservoir's water temperature. Notably, a significant negative correlation between total phosphorus and chlorophyll-a, along with a two-fold increase of this nutrient throughout the day during the rainy season, underscores the influence of the phytoplankton community dynamics on the diel nutrient variation. Chemical stratification of dissolved oxygen occurred during dry and rainy seasons, indicating that even during the dry season, where there is no significant inflow, the internal nutrient loading can also significantly impact the water quality of a reservoir. This study advances the understanding of diel water quality dynamics in tropical semiarid reservoirs, shedding light on both climatic and anthropogenic influences on water resources.

Risks to Human Health from Mercury in Gold Mining in the Coastal Region of Ecuador.

Artisanal and small-scale gold mining (ASGM) plays a crucial role in global gold production. However, the adoption of poor mining practices or the use of mercury (Hg) in gold recovery processes has generated serious environmental contamination events. The focus of this study is assessing the concentration of Hg in surface waters within the coastal region of Ecuador. The results are used to conduct a human health risk assessment applying deterministic and probabilistic methods, specifically targeting groups vulnerable to exposure in affected mining environments. Between April and June 2022, 54 water samples were collected from rivers and streams adjacent to mining areas to determine Hg levels. In the health risk assessment, exposure routes through water ingestion and dermal contact were considered for both adults and children, following the model structures outlined by the U.S. Environmental Protection Agency. The results indicate elevated Hg concentrations in two of the five provinces studied, El Oro and Esmeraldas, where at least 88% and 75% of the samples, respectively, exceeded the maximum permissible limit (MPL) set by Ecuadorian regulations for the preservation of aquatic life. Furthermore, in El Oro province, 28% of the samples exceeded the MPL established for drinking water quality. The high concentrations of Hg could be related to illegal mining activity that uses Hg for gold recovery. Regarding the human health risk assessment, risk values above the safe exposure limit were estimated. Children were identified as the most vulnerable receptor. Therefore, there is an urgent need to establish effective regulations that guarantee the protection of river users in potentially contaminated areas. Finally, it is important to continue investigating the contamination caused by human practices in the coastal region.

Water quality assessment methods of the highland Andean rivers: A scoping systematic review.

Water is a resource that influences sustainable development in different ways in social, economic, and environmental aspects, being the Andes the major provider of this resource. However, they have been affected mainly by anthropogenic activities due to the proximity of settlements in the watersheds, so they tend to have more significant contamination, and their evaluation is essential to mitigate problems for those who consume them. However, despite being a fundamental resource and one of the main contributors of water, it is not so studied, so the present study aims to determine the studies based on the water quality of the high mountain rivers of the Andes by using a PRISMA methodology with the scoping review extension, based on search techniques, inclusion and exclusion criteria, and monitoring tables, in order to maintain a line of research attached to the objective of the study. After using the methodology, ten articles were obtained, which were analyzed after a bibliometric analysis to determine features of interest, such as countries in which the studies were carried out, years of publication, methodologies used, and authors' consensus. High Andean rivers' importance, the need for more studies within these areas, and the lack of suitable indexes for these unique ecosystems are highlighted.

Multispecies and multibiomarker assessment of fish health from Iguaçu River reservoir, Southern Brazil.

This study investigated the impact of micropollutants on fish health from Segredo hydroelectric reservoir (HRS) along the Iguaçu River, Southern Brazil, contaminated by urban, industrial, and agricultural activities. This is the first comprehensive study assessment in the river after the severe drought in the 2020s in three fish species from different trophic levels Astyanax spp. (water column depth/omnivorous), Hypostomus commersoni (demersal/herbivorous), and Pimelodus maculatus (demersal/omnivorous). Animals, water, and sediment samples were collected from three distinct sites within the reservoir: Floresta (upstream), Iratim (middle), and Station (downstream). The chemical analysis revealed elevated concentrations of metals (Al, Cu, Fe) and the metalloid As in water, or Cu, Zn, and As in sediment, surpassing Brazilian regulatory limits, while the organic pollutants as DDT, PAHs, PCBs, and PBDEs were found under the Brazilian regulatory limits. The metal bioaccumulation was higher in gills with no significant differences among sites. The species Astyanax spp. and H. commersoni displayed variations in hepatosomatic index (HSI) and P. maculatus in the condition factor index (K) between sites, while adverse effects due to micropollutants bioaccumulation were observed by biochemical, genotoxic, and histopathological biomarkers. The principal component analysis and integrated biomarker response highlighted the upstream site Floresta as particularly inhospitable for biota, with distinctions based on trophic level. Consequently, this multifaceted approach, encompassing both fish biomarkers and chemical analyses, furnishes valuable insights into the potential toxic repercussions of micropollutant exposure. These findings offer crucial data for guiding management and conservation endeavors in the Iguaçu River.

Quali-quantitative water behaviour in an intensive swine production catchment in the Atlantic Forest biome, Southern Brazil.

Agriculture is an essential economic activity in Brazil. However, it is also the main source of water quality degradation. Monitoring catchments with agricultural land use is a way to generate information on a scale to identify causes and sources of water quality degradation. This work used monitoring data derived from hydrology and the quality of surface and underground water in an intensive agricultural catchment in the Atlantic Forest biome. The Fortaleza River catchment is located in the western part of Santa Catarina state in southern Brazil and has 62 km2 of drainage area. Hydrological and water quality monitoring was conducted for 7 years at two fluviometric stations, three lysimeters, one meteorological station, and one piezometer. Data on precipitation, temperature, water flow, surface runoff, drainage, and water quality were used. Statistical analyses were also developed. Precipitation between 2013 and 2019 presented a homogeneous distribution in monthly and annual data, with January and July the months with the highest and lowest values, respectively. Statistical difference in the average and Q95 flows was found in upstream and downstream fluviometric sections. In terms of quality, statistical differences were identified for ammonium, nitrate, and potassium concentrations, which had higher concentrations in lysimeter runoff, indicating direct influence of agricultural activity on water quality. Principal component analysis (PCA) indicated that (i) surface water presented a positive relationship in Component 1 for the magnesium-calcium, sulphate-chloride, and acetate-bromide groups and a negative relationship for phosphate-nitrate; (ii) in lysimeters, the positive relationship occurred for Component 2 for the phosphate-chloride and sulphate-nitrate groups and was negative for ammonium-lithium and calcium-potassium-magnesium; and (iii) in piezometer, positive relationships were found for chloride-sodium and phosphate-nitrite pairs, while negative relationships were found for calcium-magnesium.

Occurrence of Pharmaceutical Micropollutants in Lake Nahuel Huapi, Argentine Patagonia.

Tourism is one of the most important activities for the economy of Nor Patagonia Argentina. In Bariloche City, located on the shores of Lake Nahuel Huapi, both the permanent and the temporary populations have increased significantly in recent decades, and this has not necessarily been accompanied by an improvement in sewage networks. Emerging micropollutants such as pharmaceutical compounds reach aquatic systems directly, in the absence of a domestic sewage network, or through effluents from wastewater treatment plants (WWTP), which do not efficiently remove these substances and represent a major threat to the environment. Therefore, the objective of our study was to monitor the presence of pharmaceutical compounds discharged both through wastewater effluents and diffusely from housing developments into Lake Nahuel Huapi. The results obtained demonstrate the presence of pharmaceuticals in Lake Nahuel Huapi with concentrations ranging from not detectable (ND) to 110.6 ng L-1 (caffeine). The highest pharmaceutical concentration recorded in WWTP influent corresponded to caffeine (41728 ng L-1), and the lowest concentration was paracetamol (18.8 ng L-1). The removal efficiency of pharmaceuticals in the WWTP was calculated, and ranged from 0% for carbamazepine to 66% for ciprofloxacin. This antibiotic showed the lowest % of attenuation (73%) in Lake Nahuel Huapi. These results on the occurrence of a wide variety of pharmaceuticals are the first generated in Patagonia, representing a regional baseline for this type of micropollutant and valuable information for the subsequent design of removal strategies for emerging pharmaceutical pollutants in surface water. Environ Toxicol Chem 2024;43:1274-1284. © 2024 SETAC.

Electrochemical processes for the treatment of contaminant-rich wastewater: A comprehensive review.

Global water demand and environmental concerns related to climate change require industries to develop high-efficiency wastewater treatment methods to remove pollutants. Likewise, toxic pollutants present in wastewater negatively affect the environment and human health, requiring effective treatment. Although conventional treatment processes remove carbon and nutrients, they are insufficient to remove pharmaceuticals, pesticides, and plasticizers. Electrochemical processes effectively remove pollutants from wastewater through the mineralization of non-biodegradable pollutants with consequent conversion into biodegradable compounds. Its advantages include easy operation, versatility, and short reaction time. In this way, this review initially provides a global water scenario with a view to the future. It comprises global demand, treatment methods, and pollution of water resources, addressing various contaminants such as heavy metals, nutrients, organic compounds, and emerging contaminants. Subsequently, the fundamentals of electrochemical treatments are presented as well as electrochemical treatments, highlighting the latest studies involving electrocoagulation, electroflocculation, electroflotation, capacitive deionization and its derivatives, eletrodeionization, and electrochemical advanced oxidation process. Finally, the challenges and perspectives were discussed. In this context, electrochemical processes have proven promising and effective for the treatment of water and wastewater, allowing safe reuse practices and purification with high contaminant removal.