Abstract: The present research is carried out for the improvement of the availability of a hydroelectric power plant through a wear-sediment quantity correlation model for the scheduling of its preventive maintenance, the data is based on the measurement of blade thicknesses, as well as visual inspection to identify discontinuities in the water equipment, once the data has been collected, data analysis techniques can be used to evaluate the condition of the Francis turbine and determine the need for preventive maintenance under working condition. The data analysis detailed is the least squares method where the independent variables considered are power and suspended particles with their nephelometric unit of measurement of turbidity in parts per million (PPM). By means of the aforementioned analysis, it is possible to complete the results with the projection of the wear to years after the data obtained from the inspection point, and it also allows taking preventive measures before a failure occurs, which helps to reduce downtime and maintenance costs. Thus, the hydroelectric power plant under study has an annual average availability of 97.21 %, reduced by the suspension of power generation due to reservoir flushing and scheduled maintenance shutdowns. While the annual average reliability is 99.89 %, it is reduced by unscheduled failures. The result of the correlation statistical model determined the preventive maintenance for improvement conditions of 98 % of the availability in the hydroelectric power plant and is reflected in the reduction of days of no electricity generation.

Resumen: La presente investigación se realiza para la mejora de la disponibilidad de una Central Hidroeléctrica a través de un modelo de correlación desgaste-cantidad de sedimentos para la programación de su mantenimiento preventivo, los datos se basan en la medición de espesores de los alabes, así como la inspección visual para identificar discontinuadas en los equipos hídricos, una vez que se han recopilado los datos, se pueden utilizar técnicas de análisis de datos para evaluar el estado de la turbina Francis y determinar la necesidad de mantenimiento preventivo bajo condición de trabajo. El análisis de datos que se detalla es el método de mínimos cuadrados donde las variables independientes que se consideran son potencia y partículas de suspensión con su unidad de medida nefelométricas de turbidez en partes por millón (PPM). Mediante el análisis mencionado se logra culminar los resultados con la proyección del desgaste a años posteriores a los datos obtenidos del punto de inspección, además que permite tomar medidas preventivas antes de que se produzca una falla, lo que ayuda a reducir el tiempo de inactividad y los costos de mantenimiento. Es así como la Central Hidroeléctrica en estudio tiene un promedio anual del 97.21 % de disponibilidad, se reduce por la suspensión de la generación eléctrica, debido al lavado del embalse y las paradas por mantenimiento programado. Mientras que, la confiabilidad promedio anual es el 99.89 %, se reduce por fallas no programadas. El resultado del modelo estadístico de correlación determino el mantenimiento preventivo por condiciones de mejora del 98 % de la disponibilidad en la Central Hidroeléctrica y se refleja en la disminución de días de no generación eléctrica.

Abstract — The use of submerged vanes has been experimentally validated as an effective method for controlling local scour and stabilizing riverine structures. This study evaluates the efficacy of submerged vanes in mitigating local erosion around a square bridge pier. Four experiments were conducted under controlled conditions in the sedimentation channel of the Laboratory of the Faculty of Civil and Environmental Engineering at the National Polytechnic School in Quito, Ecuador. Acrylic submerged vanes were installed upstream of the pier at a 15° attack angle relative to the flow direction, aiming to modify the velocity distribution and sediment transport dynamics. The experimental results showed that submerged vanes reduced the maximum scour depth by up to 60 % compared to tests without vanes, with an average reduction of approximately 58 %. This significant reduction was attributed to the generation of vortices that redistributed sediment, resulting in shallower and more stable scour holes. Furthermore, the average sediment transport downstream decreased by approximately 40 %, further validating the vanes' efficiency in controlling erosive processes. The vanes demonstrated consistent effectiveness across varying flow rates and sedimentation conditions, underscoring their practical adaptability. By modifying flow dynamics and reducing bed shear stress, the vanes provided reliable scour protection regardless of the hydraulic conditions tested. This study highlights the submerged vanes' potential as a viable, economical, and innovative solution for protecting riverine infrastructures, particularly bridge piers, against erosive forces. Their scalability and adaptability to different hydraulic conditions make them suitable for mitigating scour in river systems with high sediment transport activity and for retrofitting existing infrastructure to enhance its stability. This research contributes to the body of knowledge on local scour mitigation by presenting a replicable experimental methodology and emphasizing the practical applicability of submerged vanes. in hydraulic engineering. The findings suggest that submerged vanes are not only effective but also cost-efficient, making them a promising alternative to traditional scour protection methods such as riprap or aprons.

Resumen — El uso de paneles sumergidos ha sido validado experimentalmente como un método efectivo para controlar la erosión local y estabilizar estructuras fluviales. Este estudio evalúa la eficacia de los paneles sumergidos en la mitigación de la erosión local alrededor de una pila de puente cuadrada. Se realizaron cuatro experimentos bajo condiciones controladas en el canal de sedimentación del Laboratorio de la Facultad de Ingeniería Civil y Ambiental de la Escuela Politécnica Nacional en Quito, Ecuador. Los paneles sumergidos de acrílico se instalaron aguas arriba de la pila con un ángulo de ataque de 15° respecto a la dirección del flujo, con el objetivo de modificar la distribución de velocidades y la dinámica del transporte de sedimentos. Los resultados experimentales mostraron que los paneles sumergidos redujeron la profundidad máxima de socavación en hasta un 60 % en comparación con las pruebas sin paneles, con una reducción promedio de aproximadamente 58 %. Esta reducción significativa se atribuyó a la generación de vórtices que redistribuyeron el sedimento, resultando en cavidades de socavación más someras y estables. Además, el transporte promedio de sedimentos aguas abajo disminuyó aproximadamente un 40 %, lo que valida aún más la eficiencia de los paneles en el control de los procesos erosivos. Los paneles demostraron una efectividad consistente frente a diferentes caudales y condiciones de sedimentación, subrayando su adaptabilidad práctica. Al modificar la dinámica del flujo y reducir las tensiones cortantes del lecho, los paneles proporcionaron una protección confiable contra la socavación, independientemente de las condiciones hidráulicas evaluadas. Este estudio destaca el potencial de los paneles sumergidos como una solución viable, económica e innovadora para proteger infraestructuras fluviales, particularmente pilas de puentes, contra fuerzas erosivas. Su escalabilidad y adaptabilidad a diferentes condiciones hidráulicas los hacen adecuados para mitigar la socavación en sistemas fluviales con alta actividad de transporte de sedimentos y para reacondicionar infraestructuras existentes, mejorando su estabilidad. Esta investigación contribuye al cuerpo de conocimiento sobre la mitigación de la socavación local al presentar una metodología experimental replicable y resaltar la aplicabilidad práctica de los paneles sumergidos.

South Africa is host to the single richest early hominin fossil record worldwide, including many examples of the endemic species Australopithecus africanus fossils. This species was first described by Raymond Dart in 1925 from the deposits near the town of Taung. Later, many more fossils, of different species and genera, were found in the caves of the Sterkfontein and Makapan Valleys. To understand this rich and diverse fossil record, we must understand how the landscape formed (cave formation processes) and changed (mining), when this happened (geochronology), and how the fossils were accumulated and modified (taphonomy). Here we provide a review of these themes to mark the centenary of the Taung Child discovery. We mark this moment in our field by critically reflecting on the role of extractive practices, especially centred around past mining of the Caves and the exclusion of many members of research teams. The South African Fossil Hominid sites provide a unique opportunity to expand our understanding of the intersection between human evolution and changing environmental conditions, as the karstic landscape and remnant cave systems preserve both fossils and sedimentary archives of past environmental change. We offer a perspective on future research areas: more standardised excavation practices and techniques to raise the quality of data collected from the caves and new techniques to date and extract palaeoclimate data from cave deposits themselves, to provide novel insights into the world of the early australopiths. SIGNIFICANCE: This review introduces the reader to the important fossil remains and palaeoclimate archives preserved within South Africa, highlighting the key species Australopithecus africanus and marking the centenary of its first description from the site of Taung. We review the geological and exploration history of the South African hominin fossil sites and discuss how they are intrinsically linked. We explore the impact of past extractive practices on the fossil and palaeoclimatic archives for past, current and future research. We go on to emphasise members of research teams who have been crucial to the discovery and recovery of fossils but have often been excluded and remained unnamed.

EVALUATION AND COMPARISON OF COLOIDAL SYSTEMS OF UHT MILK MARKETED IN THE SOUTH AND SOUTHEAST REGIONS OF BRAZIL. Ultra high temperature (UHT) milk has great relevance in the Brazilian dairy market. Thermal processing, physical-chemical and compositional properties have relevant impact on the quality of milk processed via UHT. The emergence of new categories of this product makes the production scenario even more challenging. The aim of this study was to investigate UHT milk and the effect of food additives on it, from a colloidal perspective, in the main consumer regions. The colloidal systems of samples with or without addition of stabilizers and with or without addition of tricalcium phosphate were evaluated based on analyses of ionic calcium concentration, pH, sedimentation, HCT (heat coagulation time), ethanol stability, particle size (D90) and zeta potential. The results indicated a relevant colloidal stability for this type of matrix, in addition to an efficient industrial homogenization process. The samples that received stabilizers addition showed lower ionic calcium, higher HCT and greater ethanol stability. There was no significant difference in sediment mass and pH. The samples that received Ca3(PO4)2 addition showed higher sedimentation and lower stability to ethanol. There were no significant differences regarding ionic calcium, pH and HCT.

The aim of this study was to effectively remove Fe2+ by using ozone microbubbles in bottled mineral water to prevent sediment from occurring during storage and increase shelf life. By considering the characteristics of mineral water with low solubility of ozone and high CO2 content, a suitable ozone injection step was chosen and a new mineral water treatment method using microbubbles was proposed. As a result of the treatment of the bottled mineral water with ozone microbubbles, the concentration of the iron ion was reduced from 0.14 to 0.01 mg L-1, and the shelf life increased to 360 days. During the treatment, the concentrations of K+ and Na+ were almost unchanged, and the deposition time was reduced to one-third compared to the natural oxidation. Fe2 Fe CO content proposed 014 0 14 0.1 001 01 0.0 L1, L1 L 1, 1 L-1 36 days K Na unchanged onethird one third oxidation 0. 00 L- 3

Resumen Introducción. La pérdida de suelo es un proceso natural y complejo, el cual se puede potenciar por condiciones climáticas y labores agrícolas como la mecanización. Una forma de suelo (muy poco conocida) se debe al sedimento adherido al producto al momento de la cosecha, el cual se pierde permanentemente de los sembradíos. La cuantificación de este sedimento es un factor adicional a la pérdida de suelo por erosión y los nutrientes que pueden perderse de una parcela. Objetivo. Cuantificar la pérdida de suelo por cosecha del cultivo en dos ciclos de cultivo de cebolla (Allium cepa L.) bajo tres implementos de labranza mecanizada. Materiales y métodos. Se establecieron parcelas (240 m2 cada una) en un diseño de bloques completos al azar, las cuales se sembraron con cebolla. Al momento de la cosecha del cultivo, se recolectó el sedimento adherido a la superficie de los bulbos y se estimaron los valores de pérdida de suelo para las parcelas evaluadas. Se realizaron análisis químicos de fertilidad, utilizando las metodologías KCl-Olsen y C/N total a los sedimentos obtenidos para calcular las pérdidas de nutrimentos y materia orgánica por labores de cosecha. Resultados y discusión. Se cuantificaron cantidades de sedimento entre 594,71 ± 471,93 y 1083,94 ± 78,45 kg ha-1 ciclo-1 que se pierde de los sembradíos de cebolla de forma irreversible. En adición, se pueden perder hasta 3,04 ± 0,27 kg de N, 0,15 ± 0,02 kg de P, y 1,16 ± 0,12 kg de K por hectárea por ciclo de cultivo. Conclusiones. Los resultados obtenidos son pioneros en el estudio de erosión y pérdida de suelo por cosecha del cultivo en Costa Rica, y pueden servir de referencia para futuros estudios de manejo y conservación de suelos.

Abstract Introduction. Soil loss is a natural and complex process that can be exacerbated by climatic conditions and agricultural practices such as tillage. One form of soil loss (which is not well-known) occurs due to sediment adhered to the product at harvest time, which is permanently lost from the fields. Quantifying this sediment is an additional factor to soil loss by erosion and the potential loss of nutrients from farmlands. Objective. To quantify the soil loss due to crop harvesting (SLCH) in two onion (Allium cepa L.) crop cycles under three mechanized tillage implements. Materials and methods. Field plots (240 m2 each) were established following a complete randomized block design, and further planted with onion. Sediment adhered to the surface of the bulbs at the time of harvest was collected, and SLCH values were estimated for the evaluated plots. Fertility analyses (chemical analysis extracted in KCl-Olsen and total C/N) were conducted on the obtained sediments to calculate the loss of nutrients and organic matter due to harvesting activities. Results and discussion. They were quantified sediment values between 594.71 ± 471.93 and 1083.94 ± 78.45 kg ha-1 cycle-1 that are irreversibly lost from the onion fields. Additionally, up to 3.04 ± 0.27 kg of N, 0.15 ± 0.02 kg of P, and 1.16 ± 0.12 kg of K per hectare per cycle can be lost. Conclusions. The results obtained are pioneering in the study of erosion and soil loss due to crop harvesting in Costa Rica and can serve as a reference for future soil management and conservation studies.

Resumen Introducción: Las arqueas metanogénicas (MA) participan en la mineralización anaerobia de la materia orgánica en sedimentos de manglar, su actividad está relacionada con el calentamiento atmosférico por la producción de metano; diversas variables ambientales pueden influir en la dinámica metanogénica y la producción de metano en estos sedimentos. Objetivo: Analizar, mediante técnicas dependientes de cultivo, la abundancia de las arqueas metanógenas viables (AMV) y la producción de metano en diferentes épocas climáticas en los sedimentos del manglar El Morro-La Mancha, Veracruz, Golfo de México. Métodos: De mayo a noviembre 2019, siguiendo un transecto de salinidad, se recolectaron sedimentos del manglar del Morro-La Mancha, en tres localidades, abarcando tres diferentes épocas climáticas, secas (mayo), lluvias (octubre) y nortes (noviembre) (N = 9), cuantificándose la abundancia de las AMV mediante la técnica del Número Más Probable (NMP) con acetato y metanol como substratos; la influencia de los sulfatos en la producción de metano a partir de acetato en microcosmos, se analizó por cromatografía de gases y se evaluaron las variables químicas de salinidad, pH, Eh, carbohidratos, contenido orgánico y carbonatos en los sedimentos. Resultados: Se determinó una abundancia de AMV de 102 a 108 NMP/g de sedimento húmedo, superior a la reportada en otros estudios, dicha abundancia se incrementó cuando se utilizó metanol (104-108 NMP/g sedimento) como sustrato, en comparación con el acetato (102-105 NMP/g sedimento); la producción de metano en los microcosmos aumentó en condiciones libres de sulfatos (29.78-929.75 nmol CH4/mes) y en los sedimentos de la temporada de lluvias. Conclusión: Se destaca la influencia de las condiciones químicas de los sedimentos del manglar sobre la dinámica metanógena, determinándose que, en la temporada de lluvias, una disminución de la salinidad, Eh más electronegativos y el incremento de las fracciones orgánicas favorecieron la metanogénesis.

Abstract Introduction: Methanogenic archaea (MA), participate in the anaerobic mineralization of organic matter in mangrove sediments, their activity is related to atmospheric warming due to the production of methane; several environmental variables can influence the presence of MA and methane production in these sediments. Objective: To analyze, through culture-dependent techniques, viable methanogenic archaea (VMA) in the sediments, and the production of methane from acetate in different climatic periods in the mangrove El Morro-La Mancha, Veracruz, Gulf of Mexico. Methods: From May to November 2019, following a salinity transect, sediment samples from El Morro-La Mancha mangrove were collected at three locations, in three different climatic seasons, dry (May), rainy (October) and northern (November) (N = 9). VMA in the sediments was quantified using the Most Probable Number (MPN) technique with acetate and methanol as substrates. The influence of sulfate on methane production was analyzed from acetate in microcosm by gas chromatography and the chemical variables of salinity, pH, Eh, carbohydrates, organic content, and carbonates in the sediments were evaluated. Results: The abundance of VMA was 102 to 108 MPN/g of wet sediment, higher than that reported in other studies, this abundance was higher when methanol (104-108 MPN/g sediment) was used as substrate, compared to acetate (102-105 MPN/g sediment); methane production in the microcosms increased in sulfate-free conditions (29.78-929.75 nmol CH4/month) and in the sediments of the rainy season. Conclusion: The influence of the chemical conditions of the mangrove sediments on the methanogenic dynamics is highlighted, determining that in the rainy season, the decrease in salinity, more electronegative Eh, and the increase in organic fractions favored the methanogenesis.

Resumo A Bacia do Baixo Rio Acre está localizada em uma área de desflorestamento com implantação de pastagens para pecuária de corte em solos suscetíveis à erosão e clima equatorial. A existência de abatedouros e pecuária de corte implantada no município de Boca do Acre, no Amazonas, é um dos problemas vinculados ao desmatamento da Amazônia Brasileira. Diante desse cenário, foi apresentada uma estimativa de perdas de solo com aplicação da Equação Universal em sistema de informação geográfica. Na metodologia, foi elaborado um banco de dados com informações vetorizadas para extração das áreas dos tipos de solos e cobertura da terra, incluindo a análise espacial de declividades extraídas do modelo digital de elevação. Em decorrência da análise das áreas pelo geoprocessamento ocorrer pela vetorização, foram obtidos os cálculos das parcelas de erosão através de tabelas com os parâmetros adotados pelas referências científicas. Foi constatado que 60% da perda de solo ocorrem na área de agricultura em 11% do território da bacia hidrográfica, sendo predominantemente em áreas de assentamentos rurais do estado do Acre. Como resultado da estimativa, a perda de solos na Bacia do Baixo Rio Acre foi de 386.422 t/ha/ano, com uma produção de 46 milhões de toneladas de sedimentos por ano.

Resumen La cuenca baja del río Acre se ubica en una zona de deforestación con la implementación de pastizales para ganado vacuno en suelos susceptibles a la erosión y clima ecuatorial. La existencia de mataderos y ganado vacuno en el municipio de Boca do Acre, en el estado de Amazonas, es uno de los problemas vinculados a la deforestación en la Amazonía brasileña. Ante este escenario, se presentó una estimación de las pérdidas de suelo con la aplicación de la Ecuación Universal en un sistema de información geográfica. En la metodología, se desarrolló una base de datos con información vectorizada para extraer las áreas de tipos de suelo y cobertura del suelo, incluyendo el análisis espacial de pendientes extraído del modelo digital de elevación. Como resultado del análisis de las áreas por geoprocesamiento y vectorización, se obtuvieron los cálculos de las parcelas de erosión a través de tablas con los parámetros adoptados por los referentes científicos. Se encontró que el 60% de la pérdida de suelo ocurre en el área agrícola en el 11% del territorio de la cuenca, siendo predominantemente en áreas de asentamientos rurales en el estado de Acre. Como resultado de la estimación, la pérdida de suelo en la cuenca baja del río Acre fue de 386.422 t/ha/año, con una producción de 46 millones de toneladas de sedimentos por año.

Abstract The Lower Acre River Basin is located in an area of deforestation with the implementation of pastures for beef cattle ranching in soils susceptible to erosion and equatorial climate. The existence of slaughterhouses and beef cattle in the municipality of Boca do Acre, in the state of Amazonas, is one of the problems linked to deforestation in the Brazilian Amazon. Given this scenario, an estimate of soil losses was presented with the application of the Universal Equation in a geographic information system. In the methodology, a database was elaborated with vectorized information for the extraction of the areas of the types of soils and land cover, including the spatial analysis of slopes extracted from the digital elevation model. Due to the analysis of the areas by geoprocessing occurring by vectorization, the calculations of the erosion plots were obtained through tables with the parameters adopted by the scientific references. It was found that 60% of the soil loss occurs in the area of agriculture in 11% of the territory of the watershed, being predominantly in areas of rural settlements of the state of Acre. As a result of the estimate, soil loss in the Lower Acre River Basin was 386,422 t/ha/year, with a production of 46 million tons of sediment per year.

ABSTRACT Shrimp production generates sediment residues that contain organic matter (OM) and affect the culture due to the presence of pathogens. The objective of the study was to identify the diversity of bacteria in the sediment of a shrimp pond of the La Segua wetland, describing the shrimp production process, analysis of the physicochemical characteristics of the sediment taken at five points of the shrimp pond, and the recognition of the bacterial microbiota through the analysis of the taxonomic profile of the 16S region by high-throughput sequencing. The results showed that shrimp production in the La Segua wetland does not have pertinent environmental management. The MO content is high (15-21%), as well as organic carbon (3.25%), phosphorus (3.40 mg/g) and total nitrogen (0.37%) in relation to the criteria values considered. Thirteen groups of bacteria were recorded, highlighting the supergroup of uncultured bacteria (73.24%), Terrabacteria (7%) and Pseudomonadota (7%).

RESUMEN La producción del camarón genera residuos sedimentables que contiene materia orgánica (MO) y afecta al cultivo por la presencia de agentes patógenos. El objetivo del estudio fue identificar la diversidad de bacterias en el sedimento de una piscina camaronera del Humedal la Segua, cantón Chone-Manabí, describiendo el proceso productivo del camarón, análisis de las características fisicoquímicas del sedimento tomadas en cinco puntos de la piscina camaronera y el reconocimiento del microbiota bacteriano mediante el análisis del perfil taxonómico de la región 16S por secuenciación de alto rendimiento. Los resultados demostraron que la producción del camarón en el Humedal La Segua, no cuenta con gestión ambiental pertinente. El contenido de MO es alto (15-21%), así como el carbono orgánico (3,25%), fósforo (3,40 mg/g) y nitrógeno total (0,37%) en relación con los valores de criterios considerados. Se registraron 13 grupos de bacterias, destacando el supergrupo de bacterias no cultivadas (73,24%), Terrabacteria (7%) y Pseudomonadota (7%).

ABSTRACT Geochemical analyses of fluvial sediments from Prodeminca were integrated with geological information, structures, and reports from the Cascabel, La Plata, and Curipamba deposits. Descriptive statistics were performed on 8.522 samples of river sediments from 2º latitude south to 1° north latitude, samples taken between 1997 and 1999. The elements analyzed consisted of As, Co, Cu, Cr, Hg, Ni, Pb, Zn, Au, Mo. Geology was grouped into major lithological units based on their geological environment and age. The results of the statistics were background values and thresholds for element studied, based on its particular and overall lithological population. The associations of geochemical elements were Co-Cr-Ni-Mg-Mn-Y for the domain of Cretaceous Volcanic Sediments and Cu-Zn-Pb-Sb-Zn for the domain of Paleocene-Eocene Volcanic Sediments. The anomalous values of this study coincide with the two metallogenic epochs of the Western Cordillera. The first focused on the Eocene with the Cascabel, El Domo, La Plata and Macuchi deposits which show anomalous Zn values and the second developed in the Miocene with the Llurimagua and Telimbela deposits with anomalous Cu and Mo values respectively.

RESUMEN Los análisis geoquímicos de sedimentos fluviales de Prodeminca fueron integrados con información geológica, estructuras y reportes de los depósitos de Cascabel, La Plata y El Domo. Se realizó la estadística descriptiva de 8.522 muestras de sedimentos fluviales desde 2° de latitud sur hasta 1° de latitud norte, muestras tomadas entre 1997 y 1999. Los elementos analizados consisten en As, Co, Cu, Cr, Hg, Ni, Pb, Zn, Au, Mo. Se agrupó la geología en grandes conjuntos litológicos por su ambiente y edad geológica. Los resultados de la estadística fueron valores de fondo y umbrales para los elementos estudiados, en función de su población litológica particular y global. Las asociaciones de elementos geoquímicos fueron Co-Cr-Ni-Mg-Mn-Y para el dominio de Sedimentos Volcánicos del Cretácico y Cu-Zn-Pb-Sb-W para el dominio de Volcánicos Sedimentos del Paleoceno Eoceno. Los valores anómalos de este estudio coinciden con las dos épocas metalogénicas de la Cordillera Occidental. La primera enfocada en el Eoceno con los depósitos Cascabel, El Domo, La Plata y Macuchi los cuales muestran valores anómalos de Zn y el segundo desarrollado en el Mioceno con los depósitos Llurimagua y Telimbela con valores anómalos de Cu y Mo respectivamente.

There is currently limited knowledge concerning South African coal deposits as hosts for rare earth elements (REE). This project aims to determine the concentration of REE, including yttrium and scandium (REY+Sc) in various coal seams and adjacent sediments in borehole cores from the Ermelo, Witbank, and Waterberg coalfields in South Africa. Coal petrography (maceral count and vitrinite reflectance), XRD, XRF, sequential chemical extraction procedure (SCEP) before ICP-MS, and mineral liberation analysis (MLA) were conducted on the coal and associated sediment samples. The coals were inertinite-rich, medium-rank bituminous coal, with moderate to high ash content. The two dominant minerals in all the coalfields are kaolinite and quartz, except for sample ZBS2M, where dolomite was dominant. The dominant major oxides are Al2O3, SiO2, Fe2O3, and CaO, which concur with the XRD results. The ICP-MS results following SCEP indicated that both coal and the associated sediments were light REY+Sc dominant. There was also an elevation of medium REY+Sc in the Witbank coal's associated sediment samples. Notably, the samples with the highest REY+Sc results were the sediment samples. The Waterberg samples had the lowest REY+Sc from both the coal (less than 2 μg/g to 7 μg/g) and associated sediments (2 μg/g to 15 μg/g). While the highest REY+Sc was yielded from the Witbank-associated sediments (500 μg/g to 2,500 μg/g). The carbonate fraction step proved to be the most successful leaching step, as most REY+Sc was recovered in that step for all coalfields. In addition to the carbonate fraction, the silicates and sulfide fraction in the Witbank samples, and the ion-exchangeable fraction for the Waterberg-associated sediments samples proved successful in leaching out the REY+Sc. MLA determined that monazite and xenotime in all the coal samples were the REY+Sc-bearing minerals.

Resumen Este trabajo presenta los resultados de investigaciones en la localidad arqueológica Huaycondo, ubicada en el sur de Punilla, provincia de Córdoba, Argentina. La metodología de campo consistió en prospecciones, sondeos y excavaciones sistemáticas (mediante matriz de Harris). El registro material cerámico y lítico recuperado en uno de los sectores, HUAY 2, fue abordado tecno morfológicamente y para el caso de la cerámica, también se analizó estilísticamente. Los resultados indican que el sector 1 (HUAY 1) fue un espacio techado, a partir del hallazgo de orificios que se vinculan con la colocación de postes y un nivel de compactación del sedimento. En el sector 2 (HUAY 2), se llevaron a cabo actividades de talla, uso y descarte de instrumentos líticos, y de manufactura y consumo de recipientes cerámicos y otros objetos producidos en arcilla, asociados a un nivel de compactación del sedimento. En el sector 3 (HUAY 3) no se identificó un nivel de compactación definido, por lo que habría que continuar los trabajos. En los tres sectores del sitio se obtuvieron fechados radiocarbónicos pertenecientes a ocupaciones humanas del Holoceno tardío final (ca. 1000-360 AP). Estos espacios domésticos, vinculados a diversas tareas de manufactura, procesamiento, consumo, uso y descarte de productos cerámicos, líticos, faunísticos y vegetales, constituyen formas de reproducción social con vínculos comunitarios locales y extra-regionales.

Abstract This paper presents the results of investigations in the archaeological locality Huaycondo located in the south of Punilla, Córdoba province, Argentina. The field research consisted of prospecting, test pits, and systematic excavations (using Harris matrix). The pottery and lithic material record recovered in one of the sectors, HUAY 2, was techno-morphologically approached and in the case of the ceramics also was stylistically analyzed. The results indicate that HUAY 1 was a roofed space based on the finding of holes that are linked to the placement of poles and a level of sediment compaction. In HUAY 2, activities like knapping, use, and discarding of lithic tools, manufacturing and consumption of pottery vessels and other objects made of clay associated with a level of sediment compaction were carried out. A defined compaction level was not identified in HUAY 3 therefore, the work would have to continue. In the three sectors of the site, radiocarbon dates belong to human occupations from the final late Holocene (ca. 1000-360 BP) were obtained. These domestic spaces, linked to various tasks of manufacturing, processing, consumption, use and disposal of ceramic, lithic, fauna and plant products, constitute forms of social reproduction with local and extra-regional community ties.

Abstract The Amuyo lagoons, located in the river Camarones basin in the highlands of northern Chile, have geo-tourist appeal due to their hydrothermal fluids and suspended solids, which are deposited in the surroundings with bright colors. The objective was to evaluate and compare, in the three lagoons, the physicochemical properties and the total concentrations of As-B-Cd-Co-Cu-Fe-Mn-Mo-Ni-Sb-Si-V-Zn in samples (n = 12) of red, yellow, and green sediments; the quality of surface waters; geochemical relationships; and the association between As and trace elements. There is a risk of exposure to As, B, Mn, Sb, and Zn. The green and yellow sediments reach 12% As, while the red 4% exceeds the levels of Si, Fe, Mn, and Zn. As correlates positively with Sb and Zn but negatively with Ni, Si, V, Co, and Mn. Sb (98 mg/kg) is concentrated in the green and yellow sediments, and twice B (163 mg/kg) is found in the green. The red sediment can be classified as siliceous (33 g/kg), with higher concentrations of Mn (9.1 g/kg), V (61 mg/kg), Co (41 mg/kg), and Ni (20 mg/kg), but there are no signs of organic matter, unlike the others that presented 3.3%. The three sediments showed similar levels of Fe (11 g/kg), Zn (258–370 mg/kg), and Cu (21.4–32.1 mg/kg), without signs of Mo and Cd. The composition of the waters is similar and is classified as neutral, brackish, and sodium chloride, which mobilize high concentrations of As (15–21 mg/l), B (35–42 mg/l), P-PO4−3 (2.4–3.0 mg/l) and Si (15 mg/l).

Resumen Las tres lagunas de Amuyo, situadas en el altiplano de la cuenca del río Camarones, norte de Chile, tienen atractivo geo turístico por sus fluidos hidrotermales y sólidos suspendidos, que se depositan en los alrededores de colores vistosos. El objetivo fue evaluar y comparar en las tres lagunas, las propiedades fisicoquímicas y las concentraciones totales de As-B-Cd-Co-Cu-Fe-Mn-Mo-Ni-Sb-Si-V-Zn en muestras (n = 12) de sedimentos rojo, amarillo y verde depositados alrrededor; la calidad de las aguas superficiales; las relaciones geoquímicas y la asociación entre As y los elementos traza. Existe riesgo de exposición por As, B, Mn, Sb y Zn. Los sedimentos verde y amarillo alcanzan 12 % de As, mientras que el rojo un 4%, superando los niveles de Si, Fe, Mn y Zn; As correlaciona positivo con Sb y Zn, pero negativo con Ni, Si, V, Co y Mn. En los sedimentos verde y amarillo se concentra Sb (98 mg/kg) y se halló en el verde el doble de B (163 mg/kg). El sedimento rojo puede ser clasificado como silíceo (33 g/kg), con mayores concentraciones de Mn (9,1 g/kg), V (61 mg/kg), Co (41 mg/kg) y Ni (20 mg/kg); pero, no hay indicios de materia orgánica, a diferencia de los otros que presentaron un 3,3%. Los tres sedimentos mostraron niveles similares en Fe (10,5 g/kg), Zn (269 - 375 mg/kg) y Cu (23,7 - 32,8 mg/kg), sin señas de Mo y Cd. Las aguas de las tres lagunas poseen composición semejante, clasificadas como neutras, salobres y clorurada sódica, que movilizan elevadas concentraciones de As (15 - 21 mg/l), B (35 - 42 mg/l), P-PO4−3 (2,4 - 3,0 mg/l) y Si (15 mg/l).

Verlorenvlei is a globally important RAMSAR wetland on the arid west coast of South Africa. A prolonged drought between 2016 and 2021 and increasing competition for water from the agricultural sector resulted in extremely low water levels. We used historical aerial and satellite imagery from 1942 and rainfall and water level data for the past 50 years, to assess habitat changes within the estuarine functional zone of the Verlorenvlei Estuarine Lake. Prior to the drought, lake water levels and water surface area remained stable (1113 ± 27 ha (SE)). Since then, there has been a 64% decrease in open water area, exposing 193 ha of sandbanks, of which 190.9 ha were hyper-sulfidic pyrite-rich. The water in the lower lake was hypersaline (>100), and in the middle, it was acidic (pH<3). The low water level plus sediment and nutrient input from surrounding agriculture resulted in a localised increase in reeds. Additional pressures, such as fires, have reduced the above-ground biomass of reeds and sedges, potentially altering surface morphology and reducing stored carbon. Despite flooding and filling up in June 2023, the lake remained in an acidic state (3.9-4.3). Similar low-lake level, hypersaline and acidic conditions are predicted to become more common under future climate change scenarios where aridity and extreme weather events are anticipated. Inflow of fresh water into the estuary and control of farming practices are required to keep the Verlorenvlei in a functional state, with long-term monitoring necessary to assess the ecological condition in response to restoration actions. SIGNIFICANCE: We assessed the habitat changes in Verlorenvlei, an estuarine lake on the arid west coast of South Africa. Estuarine lakes are scarce, and an extended drought greatly reduced the water surface area, exposing hyper-sulfidic pyrite-rich soils, leading to lake acidification and a negative response from biota. Competition for water from agribusiness and the burning of reeds are added pressures. Subsequent heavy rains have been slow to buffer lake acidity, and the impacts thereof serve as a warning for the management of similar ecosystems and their ecological water requirements, especially under climate change where extreme weather conditions, increased aridity and competition for water are realities.

ABSTRACT The rock-fluid interaction is associated with formation damage and occurs due to the introduction of foreign fluids that cause chemical and physical imbalances in the rock matrix and in the fluids insides, which reduces the permeability of formation The objective of the research is to evaluate properties of rock-fluid interaction in an improved recovery process. The research is developed on a laboratory scale with injection of chemical formulation, in search of alternatives for the improvement of oil production and the increase of the recovery factor of the reservoirs. Wettability tests and physical-chemical characterization of the injected fluids and effluents (total dissolved solids, density, conductivity, chloride, calcium, magnesium and pH) were carried out before and after contact with the formation. Based on determinations of density, water and sediment content, asphaltenes and rheological behavior, the characterization of the crude oil from the Seboruco well was carried out, as well as the layer water that was analyzed for its ionic composition and its classification. Such tests indicated a heavy and pseudoplastic crude oil, and a sodium hydrocarbonated layer water. The rock-fluid interaction tests showed significant changes in the wettability of the rock, from to oil-wet to water-wet. The analyzes of the effluents corroborated ionic exchange in the rock-fluid system such as: The increases in pH and increased content of chloride, calcium and magnesium obtained during the formulation step, which in some way favored the displacement of crude oil in the porous medium.

RESUMEN La interacción roca-fluido se asocia al daño de la formación y ocurre por introducción de “fluidos extraños” que causan desequilibrios químicos y físicos en la matriz de la roca y en los fluidos en su interior, lo que reduce la permeabilidad de la formación. La investigación tiene como objetivo: evaluar propiedades de interacción roca-fluido en un proceso de recuperación mejorada, a escala de laboratorio, con inyección de formulación química, en búsqueda de alternativas para el mejoramiento de la producción de petróleo e incremento del factor de recobro de los yacimientos. Se realizaron ensayos de mojabilidad y caracterización física y química de los fluidos inyectados y los efluentes (sólidos totales disueltos, densidad, conductividad, cloruro, calcio, magnesio y pH) antes y después del contacto con la formación. Sobre la base de determinaciones de densidad, contenido de agua y sedimento, asfaltenos y comportamiento reológico, se realizó la caracterización del crudo del pozo Seboruco y también del agua de capa que fue analizada en cuanto su composición iónica y su clasificación. Tales ensayos indicaron un crudo pesado y seudoplástico y el agua de capa del tipo hidrocarbonada sódica. Los ensayos de interacción roca-fluido evidenciaron cambios significativos en la mojabilidad de la roca, de oleohumectada a acuohumectada. Los análisis de los efluentes corroboraron intercambio iónico en el sistema roca-fluido como son: los incrementos de pH y aumento de contenido de cloruro, calcio y magnesio, obtenido al paso de la formulación, que en alguna forma favorecieron al desplazamiento del crudo en el medio poroso.