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A hydrogeological conceptual model of the source, circulation pathways and temporal variation of a low-enthalpy thermal spring in a fractured limestone setting is derived from a multidisciplinary approach. St. Gorman's Well is a thermal spring in east-central Ireland with a complex and variable temperature profile (maximum of 21.8 °C). Geophysical data from a three-dimensional(3D)audio-magnetotelluric(AMT) survey are combined with time-lapse hydrogeological data and information from a previously published hydrochemical analysis to investigate the operation of this intriguing hydrothermal system. Hydrochemical analysis and time-lapse measurements suggest that the thermal waters flow within the fractured limestones of the Carboniferous Dublin Basin at all times but display variability in discharge and temperature. The 3D electrical resistivity model of the subsurface revealed two prominent structures: (1) a NW-aligned faulted contact between two limestone lithologies; and (2) a dissolutionally enhanced, N-aligned, fault of probable Cenozoic age. The intersection of these two structures, which has allowed for karstification of the limestone bedrock, has created conduits facilitating the operation of relatively deep hydrothermal circulation (likely estimated depths between 240 and 1,000 m) within the limestone succession of the Dublin Basin. The results of this study support a hypothesis that the maximum temperature and simultaneous increased discharge observed at St. Gorman's Well each winter is the result of rapid infiltration, heating and recirculation of meteoric waters within a structurally controlled hydrothermal circulation system.The online version contains supplementary material available at 10.1007/s10040-021-02393-1.Un modèle conceptuel hydrogéologique de la source, des voies de circulation et de la variation temporelle d’une source thermale à faible enthalpie dans un contexte de calcaire fracturé est dérivé d’une approche multidisciplinaire. St. Gorman’s Well est une source thermale du centre-est de l’Irlande avec un profil de température complexe et variable (maximum de 21.8 °C). Les données géophysiques d’un levé audio-magnétotellurique (AMT) en trois dimensions (3D) sont combinées avec des données hydrogéologiques à intervalles de temps et des informations provenant d’une analyse hydrochimique publiée précédemment pour étudier le fonctionnement de cet intrigant système hydrothermal. L’analyse hydrochimique et les mesures à différentes périodes suggèrent que les eaux thermales s’écoulent à tout moment dans les calcaires fracturés du bassin carbonifère de Dublin, mais présentent une variabilité de débit et de température. Le modèle de résistivité électrique 3D du sous-sol a révélé deux structures importantes: (1) un contact faillé orienté NW entre deux lithologies calcaires; et (2) une faille alignée au Nord, améliorée par dissolution, d’âge cénozoïque probable. L’intersection de ces deux structures, qui a permis la karstification du socle calcaire, a créé des conduits facilitant le fonctionnement d’une circulation hydrothermale relativement profonde (profondeurs estimées vraisemblablement entre 240 et 1,000 m) au sein de la succession calcaire du bassin de Dublin. Les résultats de cette étude appuient l’hypothèse selon laquelle la température maximale et l’augmentation simultanée du débit observés à St. Gorman’s Well chaque hiver sont le résultat d’une infiltration, d’un réchauffement et d’une recirculation rapides des eaux météoriques dans un système de circulation hydrothermale structurellement contrôlé.Se deriva un modelo conceptual hidrogeológico de la fuente, las vías de circulación y la variación temporal de un manantial termal de baja entalpía en un entorno de caliza fracturada a partir de un enfoque multidisciplinar. Gorman’s Well es un manantial termal en el centro-este de Irlanda con un perfil de temperatura complejo y variable (máximo de 21.8 °C). Los datos geofísicos de un estudio audio-magnetotelúrico (AMT) tridimensional (3D) se combinan con los datos hidrogeológicos de un lapso de tiempo y la información de un análisis hidroquímico previamente publicado para investigar el funcionamiento de este intrigante sistema hidrotermal. El análisis hidroquímico y las mediciones a intervalos de tiempo sugieren que las aguas termales fluyen dentro de las calizas fracturadas de la cuenca carbonífera de Dublín en todo momento, pero muestran variabilidad en la descarga y la temperatura. El modelo de resistividad eléctrica tridimensional del subsuelo reveló dos estructuras prominentes: (1) un contacto de falla alineado al NW entre dos litologías calcáreas; y (2) una falla de disolución incrementada, alineada al N, de probable edad cenozoica. La intersección de estas dos estructuras, que ha permitido la karstificación del lecho rocoso calcáreo, ha creado conductos que facilitan el funcionamiento de una circulación hidrotermal relativamente profunda (probablemente a profundidades estimadas entre 240 y 1,000 m) dentro de la sucesión calcárea de la cuenca de Dublín. Los resultados de este estudio apoyan la hipótesis de que la temperatura máxima y el aumento simultáneo de la descarga observados en St. Gorman’s Well cada invierno son el resultado de una rápida infiltración, calentamiento y recirculación de aguas meteóricas dentro de un sistema de circulación hidrotermal estructuralmente controlado.通过多学科方法, 建立了裂缝型石灰岩环境中低焓温泉的来源、循环路径和时间变化的水文地质概念模型。圣戈尔曼井是爱尔兰中东部的温泉, 温度分布复杂多变 (最高21.8 °C)。将三维 (3D) 音频-大地电磁 (AMT) 调查的地球物理数据与延时水文地质数据和先前发布的水化学分析信息相结合, 调查了有趣的热液系统运行情况。水化学分析和延时测量表明, 热水一直在石炭系都柏林盆地的裂缝型石灰岩内流动, 但流量和温度有变异性。地下的 3D 电阻率模型揭示了两个突出的结构:(1) 两个石灰岩岩性之间的 NW 向断层接触; 和 (2) 可能新生代的溶蚀增强的和N向的断层。两个结构的交叉点使石灰岩基岩发生岩溶作用, 形成了通道, 促进了都柏林盆地石灰岩序列内相对较深的热液循环 (估计深度可能在 240 至 1,000 m 之间)作用。通过这项研究发现每年冬天在圣戈尔曼井观察到的最高温度和同时增加的排泄量是结构控制的热液循环系统中大气水快速入渗、加热和再循环的结果。.Um modelo hidrogeológico conceitual da fonte, vias de circulação e variação temporal de uma fonte termal de baixa entalpia em um ambiente de calcário fraturado é derivado de uma abordagem multidisciplinar. O poço de St. Gorman é uma fonte termal no centro-leste da Irlanda com um perfil de temperatura complexo e variável (máximo de 21.8°C). Os dados geofísicos de uma pesquisa áudio-magnetotelúrica (AMT) tridimensional (3D) são combinados com dados hidrogeológicos em intervalos de tempo e informações de uma análise hidroquimica publicada anteriormente, para investigar a operação deste intrigante sistema hidrotérmico. A análise hidroquimica e as medições em intervalos de tempo sugerem que as águas termais fluem de dentro dos calcários fraturados da Bacia Carbonifera de Dublin o tempo todo, mas exibem variabilidade na descarga e na temperatura. O modelo de resistividade elétrica 3D da subsuperfície revelou duas estruturas proeminentes: (1) um contato defeituoso alinhado a NO entre duas litologias de calcário; e (2) uma falha dissolucionalmente aumentada, alinhada a N, de provável idade Cenozóica. A intersecção dessas duas estruturas, que permitiu a carstificação da rocha calcária, criou condutos que facilitam a operação de circulação hidrotérmica relativamente profunda (profundidade estimada entre 240 e 1,000 m) dentro da sucessão de calcário da Bacia Dublin. Os resultados desse estudo suportam a hipótese de que a temperatura máxima e o aumento simultâneo da descarga observada no poço de St. Gorman a cada inverno é o resultado da rápida infiltração, aquecimento e recirculação de águas meteóricas dentro de um sistema de circulação hidrotérmica estruturalmente controlado.

The dating of organic findings is a fundamental task for many scientific fields. Radiocarbon dating is currently the most commonly used method. For wood, dendrochronology is another state‐of‐the‐art method. Both methods suffer from systematic restrictions, leading to samples that have not yet been able to be dated. Molecular changes over time are reported for many materials under different preservation conditions. Many of them are intrinsically monotonous. These monotonous molecular decay (MD) patterns can be understood as clocks that start at the time when a given molecule was formed. Factors that influence these clocks include input material composition and preservation conditions. Different wood species, degrees of pyrolysis, and pretreatments lead to different prediction models. Preservation conditions might change the speed of a given clock and lead to different prediction models. Currently published models for predicting the age of wood, paper, and parchment depend on infrared spectroscopy. In contrast to radiocarbon dating, dating via MD does not comprise a single methodology. Some clocks may deliver less precise results than the others. Ultimately, developing a completely different, new dating strategy‐such as MD dating–will help to bring to light a treasure trove of information hidden in the darkness of organic findings., This review focuses on molecular changes over time. Having been discussed since the 1960s, the variety of molecular clocks includes the change in amino acids in the primary structure of a protein over time. Molecular decay (MD) has a mainly monotonous function, a prerequisite to serving as such a clock. In addition, such clocks need a defined starting point and a defined decay function. In contrast to the decay of alpha and beta emitters, MD is influenced by several environmental factors indicated by preservation conditions. The MD method has the potential to be used for different organic materials and different scientific fields.

Several different approaches have been developed to model the specific characteristics of karst aquifers, taking account of their inherent complex spatial and temporal heterogeneities. This paper sets out the development of a semidistributed modelling approach for applications in an Irish karst context using urban drainage software. The models have proven to be very useful for different studies, with examples given for the ecohydrology of ephemeral karst lakes, extreme groundwater-flood alleviation, karst network investigation, submarine groundwater discharge, and quantification of different recharge and flow components. The limitations of the approach are also highlighted, in particular not being able to simulate diffuse infiltration and flow paths explicitly across the groundwater catchment. Hence, a more distributed, finite-difference modelling approach using MODFLOW Unstructured Grid (USG) with the newly developed Connected Linear Network (CLN) process is then compared against the semidistributed approach on the same karst catchment. Whilst it has proven difficult to achieve the same levels of model performance in simulating the spring flows in the distributed model compared to the semidistributed model, the ability to interrogate the flow paths at any point on the three-dimensional aquifer is demonstrated, which can give new insights into flows (and potential contaminant transport) through such complex systems. The influence of the proximity of highly transmissive conduits on the flow dynamics through the much-lower transmissive matrix cells in which the network is embedded has been particularly investigated.Plusieurs approches différentes ont été développées pour modéliser les caractéristiques spécifiques des aquifères karstiques, prenant en compte leurs hétérogénéités spatiales et temporelles associées à leur complexité intrinsèque. Cet article présente le développement d’une approche de modélisation semi-distribuée appliquée à un contexte karstique irlandais en utilisant un logiciel de drainage urbain. Ces modèles se sont avérés très utiles pour différentes études, avec des exemples appliqués à l’écohydrologie de lacs karstiques éphémères, l’atténuation de crues extrêmes liées aux eaux souterraines, à l’étude du réseau karstique, à la décharge des sources sous-marines et à la quantification des différentes composantes aussi bien de la recharge que du débit. Les limites de cette approche sont aussi mises en évidence, avec en particulier l’incapacité de simuler l’infiltration diffuse et les voies d’écoulement de manière explicite au sein du bassin d’alimentation d’eaux souterraines. Par conséquent, une approche de modélisation plus distribuée aux différences finies utilisant le logiciel MODFLOW avec une grille non structurée (USG) intégrant le processus récemment développé de réseau linéaire connecté (CLN) est ensuite comparée à l’approche semi-distribuée appliquée au même bassin karstique. Alors qu’il s’est avéré difficile d’atteindre les mêmes niveaux de performance du modèle concernant la simulation du débit à la source à l’aide du modèle distribué en comparaison au modèle semi-distribué, la possibilité d’examiner les voies d’écoulement en tout point de l’aquifère en 3D est démontrée, ce qui peut donner de nouvelles connaissances sur les écoulements (et le transport potentiel de contaminants) au sein de tels systèmes complexes. L’influence de la proximité de conduits hautement transmissifs sur les écoulements dynamiques au travers des cellules de transmissivité plus faible de la matrice au sein de laquelle le réseau est intégré, a été particulièrement étudiée.Se han elaborado varios enfoques diferentes para modelar las características específicas de los acuíferos kársticos, teniendo en cuenta sus complejas y propias heterogeneidades espaciales y temporales. En el presente documento se expone la elaboración de un enfoque de modelización semidistribuido para aplicaciones en un contexto kárstico de Irlanda utilizando programas informáticos de drenaje urbano. Los modelos han demostrado ser muy útiles para diferentes estudios, y se dan ejemplos para la ecohidrología de los lagos kársticos efímeros, la mitigación de las inundaciones extremas de aguas subterráneas, la investigación de redes kársticas, la descarga submarina de aguas subterráneas y la cuantificación de diferentes componentes de la recarga y el flujo. También se ponen de relieve las limitaciones del enfoque, en particular el hecho de no poder simular explícitamente la infiltración difusa y las trayectorias de flujo a través de la cuenca de captación de aguas subterráneas. Por lo tanto, un enfoque de modelización de diferencias finitas distribuidas utilizando la red no estructurada (USG) de MODFLOW con el proceso de la Red Lineal Conectada (CLN) recientemente desarrollado se compara entonces con el enfoque semidistribuido en la misma cuenca kárstica. Si bien se ha demostrado que es difícil lograr los mismos niveles de rendimiento del modelo en la simulación de los flujos de manantiales en el modelo distribuido en comparación con el modelo semidistribuido, se demuestra la capacidad de interrogar las trayectorias de los flujos en cualquier punto del acuífero tridimensional, lo que puede dar nuevos conocimientos sobre los flujos (y el transporte de contaminantes potenciales) a través de sistemas tan complejos. Se ha investigado en particular la influencia de la proximidad de conductos altamente transmisivos en la dinámica de los flujos a través de las células de la matriz transmisiva, mucho más bajas, en las que está incorporada la red.鉴于岩溶含水层内在的复杂时空异质性, 已经开发出几种不同的方法来模拟岩溶含水层的特定性质。本文提出了基于城市排水软件的半分布式模型的开发方法, 并在爱尔兰喀斯特环境中应用。该模型已被证明对不同的研究非常有用, 并举例说明了季节性的喀斯特湖的生态水文学, 极端地下水洪涝减缓, 岩溶网络调查, 海底地下水排泄以及不同补给量和流动量的量化。还强调了该方法的局限性, 特别是不能明确模拟整个地下水盆地的扩散入渗和流动路径。因此, 然后将MODFLOW非结构化网格(USG)和新开发的连接线性网络(CLN)过程耦合的分布式有限差分方法与同一个喀斯特流域的半分布式方法进行了比较。尽管已证明分 布式模型模拟的泉流量难以达到与半分布式模型相比相同水平的模型性能, 但仍展示了在三维含水层上任意点处查询流路的能力, 这可以给出分析该类复杂系统流量(以及潜在的污染物传输)的新方法。特别研究了高传输管流的邻近度对通过嵌入网络的传导率低得多单元的流动动力学的影响。.Diversas abordagens diferentes foram desenvolvidas para modelar as características específicas dos aquíferos cársticos, levando em consideração suas complexas heterogeneidades espaciais e temporais inerentes. Este artigo apresenta o desenvolvimento de uma abordagem de modelagem semidistribuída para aplicações em um contexto cárstico irlandês usando software de drenagem urbana. Os modelos provaram ser muito úteis para diferentes estudos, com exemplos dados para a ecohidrologia de lagos cársticos efêmeros, alívio de inundações subterrâneas extremas, investigação de rede cárstica, descarga de água subterrânea submarina e quantificação de diferentes componentes de recarga e fluxo. As limitações da abordagem também são destacadas, em particular não ser capaz de simular infiltração difusa e caminhos de fluxo explicitamente através da captação de água subterrânea. Portanto, uma abordagem de modelagem de diferenças finitas, mais distribuída, usando MODFLOW Unstructured Grid (USG) com o processo de Rede Linear Conectada (RLC) recém-desenvolvido é então comparada com a abordagem semidistribuída na mesma bacia cárstica. Embora tenha se mostrado difícil alcançar os mesmos níveis de desempenho do modelo na simulação dos fluxos de nascente no modelo distribuído em comparação com o modelo semidistribuído, a capacidade de interrogar os caminhos de fluxo em qualquer ponto do aquífero tridimensional é demonstrada, o que pode dar novas percepções sobre os fluxos (e o transporte potencial de contaminantes) por meio de tais sistemas complexos. A influência da proximidade de condutos altamente transmissivos na dinâmica do fluxo através das células da matriz transmissiva muito inferior nas quais a rede está inserida foi investigada particularmente.

Knowledge about the hydraulic connections between submarine groundwater discharge (SGD) and its terrestrial coastal catchment is relevant with regard to the management of marine and coastal waters in karst areas. This study applies different methods and monitoring approaches to trace SGD between the Burren Limestone Plateau and Galway Bay in western Ireland, via an excavated sinkhole shaft and deep conduit. Areas of potential SGD were first delineated based on sea surface temperature anomalies using Landsat satellite images. Two fluorescent dyes and solid wood chips were then used as tracers. Solid wood chips were tested as potential means to circumvent the problem of high dispersion in the sea, impacting on the fluorescent dyes to yield readings below the detection limits. Sampling was conducted at 10 different terrestrial locations and in the sea at Galway Bay. Offshore sampling was conducted in transects over a period of four successive days onboard of a vessel using an automated field fluorometer and a conductivity-temperature-depth sensor. No wood chips were recovered in the sea but both fluorescent dyes were successfully sampled. The estimated travel times are in the order of 100 to 354 m/h, and localised tracer readings correlate well in space and time with low conductivity readings. By confirming hydraulic connections between the two karst features and Galway Bay, the study substantiates the hypothesised importance of Variscan veins with regard to regional groundwater flow in the region.Die Kenntnis hydraulischer Zusammenhänge zwischen untermeerischen Grundwasseraustritten und deren terrestrischen Küsteneinzugsgebieten ist für die Bewirtschaftung der Meeres- und Küstengewässer in Karstgebieten von Bedeutung. Diese Studie wendet verschiedene Methoden und Messansätze an, um untermeerische Grundwasseraustritte zwischen dem Burren Kalkstein Plateau und der Galway Bucht in Westirland über einen ausgegrabenen Dolinen-Schacht und eine tiefe Karströhre zu verfolgen. Meeresbereiche mit potenziellen Grundwasseraustritten wurden zuerst unter Verwendung von Landsat-Satellitenbildern auf Grundlage von Temperaturanomalien an der Meeresoberfläche abgegrenzt. Dann wurden zwei fluoreszierende Farbstoffe und Holzspäne als Tracer verwendet. Die Holzspäne wurden als Mittel zur Umgehung des Problems starker Dispersion im Meer getestet, welche sich potentiell auf die fluoreszierenden Farbstoffe auswirken, und in Messwerten unterhalb der Nachweisgrenze resultieren kann. Die Probenahme wurde an 10 verschiedenen terrestrischen Standorten und im Meer der Galway Bucht durchgeführt. Mit einem automatisierten Feldfluorometer und einer Leitfähigkeits-, Temperatur- und Tiefensonde wurden in den jeweiligen Meeressektoren Messungen über einen Zeitraum von vier aufeinanderfolgenden Tagen an Bord eines Schiffes durchgeführt. Zwar wurden im Meer keine Holzspäne zurückgewonnen, allerdings wurden beide Fluoreszenzfarbstoffe erfolgreich gemessen. Die geschätzten Fließzeiten liegen in der Größenordnung von 100 bis 354 m/h und lokalisierte Tracer-Messwerte korrelieren räumlich und zeitlich gut mit Messwerten geringerer Leitfähigkeit. Die Bestätigung der hydraulischen Verbindungen zwischen dem Kalksteinplateau und der Bucht von Galway bestärkt die Hypothese der Bedeutsamkeit von variszischen Adern für den regionalen Grundwasserfluss.La connaissance des connexions hydrauliques entre les zones de sorties d’eaux souterraines sous-marines et le bassin terrestre côtier attenant est pertinente pour la gestion des eaux marines et côtières en zones karstiques. Cette étude applique différentes approches méthodologiques et de suivi pour tracer la sortie d’eaux souterraines sous-marines entre le plateau calcaire de Burren et la baie de Galway en Irlande de l’Ouest, via une perte et un conduit profond. Les zones de sorties potentielles d’eaux souterraines sous-marines ont été délimitées dans un premier temps sur la base d’anomalies de température des eaux de mer en utilisant des images satellites Landsat. Deux traceurs fluorescents et des copeaux de bois ont été utilisés comme traceurs. Les copeaux de bois ont été utilisés comme moyen potentiel pour contourner les problèmes de dispersion élevée dans la mer, qui impactent les traceurs fluorescents et engendrent des concentrations sous les limites de détections. L’échantillonnage a été menée sur dix sites différents à terre et en mer dans la baie de Galway. L’échantillonnage en mer e a été mené selon des profils sur une période de quatre jours successifs à bord d’un navire muni d’un fluorimètre de terrain automatique et d’un capteur de conductivité-température-profondeur. Aucun copeau de bois n’a été récupéré en mer, mais les deux traceurs fluorescents ont été échantillonnés avec succès. Les temps de séjour estimés sont de l’ordre de 100 à 354 m/h, et les valeurs de traceurs localisées corrèlent bien en espace et en temps avec les basses valeurs de conductivité électrique. En confirmant les connexions hydrauliques entre les deux phénomènes karstiques et la baie de Galway, l’étude corrobore l’hypothèse de l’importance des veines du cycle varisque sur l’organisation des écoulements régionaux d’eau souterraine dans la région.El conocimiento de las conexiones hidráulicas entre la descarga submarina de aguas subterráneas (SGD) y su cuenca costera terrestre es relevante para la gestión de las aguas marinas y costeras en las zonas kársticas. Este estudio aplica diferentes métodos y enfoques de monitoreo para el seguimiento de la SGD entre la meseta de caliza de Burren y la bahía de Galway en el oeste de Irlanda, a través de un pozo excavado y un conducto profundo. Las áreas de SGD potenciales fueron delineadas primero basándose en anomalías de la temperatura de la superficie del mar usando imágenes satelitales Landsat. Dos tintes fluorescentes y astillas de madera maciza se utilizaron como trazadores. Las astillas de madera maciza se probaron como medio potencial para eludir el problema de la alta dispersión en el mar, impactando en los colorantes fluorescentes para obtener lecturas por debajo de los límites de detección. El muestreo se llevó a cabo en 10 lugares terrestres diferentes y en el mar en la Bahía de Galway. El muestreo en alta mar se llevó a cabo en transectas durante un período de cuatro días consecutivos a bordo de un buque utilizando un fluorómetro de campo automatizado y un sensor de conductividad-temperatura-profundidad. No se recuperaron astillas de madera en el mar, pero se tomaron muestras exitosas de ambos tintes fluorescentes. Los tiempos de tránsito estimados son del orden de 100 a 354 m/h, y las lecturas del trazador localizadas se correlacionan bien en el espacio y el tiempo con las lecturas de baja conductividad. Al confirmar las conexiones hidráulicas entre las dos características kársticas y la Bahía de Galway, el estudio corrobora la importancia hipotética de las vetas de Variscan con respecto al flujo regional de agua subterránea en la región.在岩溶地区, 海底地下水排泄(SGD)与其陆地沿海集水区之间水力联系的认识与海洋和沿海水域的管理有关。本研究采用不同的方式和监测方法, 通过开挖的落水洞和深水管道来示踪爱尔兰西部Burren石灰岩高原和Galway湾之间的地下水排泄。首先利用Landsat卫星图像和基于海平面温度异常划定了潜在的SGD区域。然后将两种荧光染料和实木碎片用作示踪剂。测试了实木碎屑作为解决海洋中由于影响荧光染料使产生低于检测极限读数的高弥散问题的潜在手段。在Galway湾的10个不同陆面位置和海洋中进行了采样。使用自动现场荧光计和电导率-温度-深度传感器, 在船上连续四天的时间段内, 进行海洋取样。在海洋中没有回收木屑, 但两种荧光染料均已成功采样。估计的行程时间约为100至354 m/h, 局部示踪剂读数在空间和时间上与低电导率读数相关性很好。通过确定两个喀斯特地貌与Galway湾之间的水力联系, 该研究证实了华力西期脉对于该地区区域地下水流动的假设重要性。.O conhecimento sobre as conexões hidráulicas entre a descarga submarina de águas subterrâneas (DSAS) e sua captação terrestre na costa é relevante no que diz respeito ao gerenciamento de águas marinhas e costeiras em áreas cársticas. Este estudo aplica diferentes métodos e abordagens de monitoramento para rastrear a DSAS entre o platô de calcário de Burren e a baía de Galway, no oeste da Irlanda, por meio de um poço escavado e um conduto profundo. Áreas de potencial DSAS foram primeiramente delineadas com base em anomalias de temperatura da superfície do mar usando imagens do satélite Landsat. Dois corantes fluorescentes e lascas de madeira maciça foram então utilizados como marcadores. Lascas de madeira maciça foram testadas como um meio potencial para contornar o problema de alta dispersão no mar, impactando nos corantes fluorescentes para produzir leituras abaixo dos limites de detecção. A amostragem foi realizada em 10 locais terrestres diferentes e no mar na Baía de Galway. A amostragem fora da costa foi realizada em transectos durante um período de quatro dias sucessivos a bordo de uma embarcação usando um fluorômetro de campo automatizado e um sensor de condutividade-temperatura-profundidade. Nenhuma lasca de madeira foi recuperada no mar, mas os dois corantes fluorescentes foram amostrados com sucesso. Os tempos de viagem estimados são da ordem de 100 a 354 m/h, e as leituras localizadas do traçador se correlacionam bem no espaço e no tempo com as leituras de baixa condutividade. Ao confirmar as conexões hidráulicas entre as duas formações cársticas e a Baía de Galway, o estudo confirma a hipótese da importância das veias variscas em relação ao fluxo regional de águas subterrâneas na região.

Significance: Simulations have the potential to be a powerful tool when planning the placement of photoacoustic imaging system components for surgical guidance. While elastic simulations (which include both compressional and shear waves) are expected to more accurately represent the physical transcranial acoustic wave propagation process, these simulations are more time-consuming and memory-intensive than the compressional-wave-only simulations that our group previously used to identify optimal acoustic windows for transcranial photoacoustic imaging. Aim: We present qualitative and quantitative comparisons of compressional and elastic wave simulations to determine which option is more suitable for preoperative surgical planning. Approach: Compressional and elastic photoacoustic k-Wave simulations were performed based on a computed tomography volume of a human cadaver head. Photoacoustic sources were placed in the locations of the internal carotid arteries and likely positions of neurosurgical instrument tips. Transducers received signals from three previously identified optimal acoustic windows (i.e., the ocular, nasal, and temporal regions). Target detectability, image-based target size estimates, and target-to-instrument distances were measured using the generalized contrast-to-noise ratio (gCNR), resolution, and relative source distances, respectively, for each simulation method. Results: The gCNR was equivalent between compressional and elastic simulations. The areas of the −6 dB contours of point spread functions utilized to measure resolution differed by 0.33 to 3.35 mm2. Target-to-instrument distance measurements were within 1.24 mm of the true distances. Conclusions: These results indicate that it is likely sufficient to utilize the less time-consuming, less memory-intensive compressional wave simulations for presurgical planning.

The vortex interaction in the wake behind a two- and three-bladed model scale wind turbine is investigated. The two rotors have equal solidity, and produce similar power and thrust at the design tip speed ratio. Phase-averaged quantities of the wake flow from one to four rotor diameters behind the turbines are measured in a wind tunnel. It is found that the two-bladed turbine has slower wake recovery than the three-bladed turbine, and a larger velocity deficit is produced in the far wake. The tip vortices behind the two-bladed turbine is more stable than behind the three-bladed turbine, and the vortex structures exist further downwind. In a wind farm, this could reduce the power production and increase fatigue loads for the turbines operating in the wake flow, especially during stable atmospheric conditions. Content from this work may be used under the terms of theCreative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI 10.1088/1742-6596/1669/1/012027. Published under licence by IOP Publishing Ltd

The paper describes the development of a scaled model of complex terrain, suitable for terrain-wind turbine interaction wind tunnel studies, taking into account flow similarity criteria. The size and the geometry of the experimental model of the complex terrain were refined using results of CFD simulations in order to achieve the best possible flow similarity and avoid edge effects arising from the finite (relative to the rotor size) terrain geometry. Moreover, Particle Image Velocimetry was used to survey the flow field on a longitudinal plane along the terrain center line. Flow measurements with and without a wind turbine model enabled to quantitatively evaluate the speed up produced by the terrain in the region of the wind turbine and the effect of the terrain on the wake characteristics of the wind turbine model.

The study was designed to quantify the thermal conditions in tall atria in office buildings to serve as a starting point towards understanding their performance. The simulation study of a non-segmented and segmented atrium of 250 m height reveals indoor air temperature, wind velocity contours and wind pressure coefficients at various heights of each atrium type. In a hot and humid climate like that of Singapore, the internal temperatures within each atrium stack remain constant at 27°C. However, the wind velocity in the non-segmented atrium (of 0.5 - 0.7 m/s) is lower than acceptable (0.9 m/s) for human occupancy. Adding segments and a larger inlet to the atrium solves the problem of low wind velocity without increasing the effective ambient temperature within the atrium stack. Additionally, the segmented atrium offers the advantage of displaying lower buoyancy forces by lowering the pressure differential within a tall stack thereby providing better comfort conditions.

A study about the influence of polyaxial (true-triaxial) stresses on the permeability of a three-dimensional (3D) fractured rock layer is presented. The 3D fracture system is constructed by extruding a two-dimensional (2D) outcrop pattern of a limestone bed that exhibits a ladder structure consisting of a “through-going” joint set abutted by later-stage short fractures. Geomechanical behaviour of the 3D fractured rock in response to in-situ stresses is modelled by the finite-discrete element method, which can capture the deformation of matrix blocks, variation of stress fields, reactivation of pre-existing rough fractures and propagation of new cracks. A series of numerical simulations is designed to load the fractured rock using various polyaxial in-situ stresses and the stress-dependent flow properties are further calculated. The fractured layer tends to exhibit stronger flow localisation and higher equivalent permeability as the far-field stress ratio is increased and the stress field is rotated such that fractures are preferentially oriented for shearing. The shear dilation of pre-existing fractures has dominant effects on flow localisation in the system, while the propagation of new fractures has minor impacts. The role of the overburden stress suggests that the conventional 2D analysis that neglects the effect of the out-of-plane stress (perpendicular to the bedding interface) may provide indicative approximations but not fully capture the polyaxial stress-dependent fracture network behaviour. The results of this study have important implications for understanding the heterogeneous flow of geological fluids (e.g. groundwater, petroleum) in subsurface and upscaling permeability for large-scale assessments., Hydrogeology Journal, 25 (8), ISSN:1431-2174, ISSN:1435-0157

Sealing layers made of two alkaline paper mill by-products, fly ash and green liquor dregs, were placed on top of 50-year-old sulfide-containing tailings as a full-scale remediation approach. The performance and effectiveness of the sealing layers with high water content for an oxygen barrier and low hydraulic conductivity for a sealing layer in preventing the formation of acid rock drainage were evaluated 5 years after the remediation. The leaching behavior of the covered tailings was studied using batch leaching tests (L/S ratio 10 L/kg). The leaching results revealed that, in general, the dregs- and ash-covered tailings released relatively lower concentrations of many elements contained in acid rock drainage compared to those from the uncovered tailings. A change in the chemical composition and mineralogical state of the tailings was observed for the tailings beneath the covers. The increase in pH caused by the alkaline materials promoted metal precipitation. Geochemical modeling using PHREEQC confirmed most of the geochemical changes of the covered tailings. Both the ash and dregs showed potential to function as sealing materials in terms of their geochemical properties. However, mobilization of Zn and Ni from the lower part of the dregs-covered tailings was observed. The same phenomenon was observed for the lower part of the ash-covered tailings. Ash showed advantages over dregs as a cover material; based on geochemical studies, the ash immobilized more elements than the dregs did. Lysimeters were installed below the sealing layers, and infiltrating water chemistry and hydrology were studied to monitor the amount and quality of the leachate percolating through.