Flowstones from the Račiška Pečina Cave (SW Slovenia) Record 3.2-Ma-Long History

Establishing a chronology of events is a critical step in reconstructing the palaeoclimate and it is important for all types of environmental records, including speleothems. Here, we analysed a unique series of flowstones deposited between 3.2 Ma (marine isotope stage (MIS) Km3) and 0.08 Ma (MIS 5). The studied flowstones are located in a classic karstic environment, the Račiška Pečina Cave in south-western Slovenia. Further, a detailed chronology of events was constructed based on oxygen isotope stratigraphy (OIS), combined with magnetostratigraphy and U-series dating. Two curves were selected as reference records where the LR04 record was used as the global curve and a Mediterranean record was used as the regional curve. The Račiška Pečina profile was divided into two segments separated by a principal disconformity. The lower segment correlated better with the regional Mediterranean curve, while the upper segment was with the global LR04 curve. These findings suggest that the main factors controlling environmental conditions in the cave area changed between 3.2 and 0.8 million years ago.

Diagnóstico físico-conservacionista do ambiente cárstico da bacia do córrego Cana-brava, Aurora do Tocantins (TO, Brasil) / Physical diagnostic-conservationist of karstic environment of watershed Cana-brava river, Aurora do Tocantins (TO, Brasil)

<p>Atualmente, é possível constatar um crescente aumento da degradação do meio, o qual está relacionado ao desenvolvimento das atividades humanas. Os terrenos cársticos são ambientes muito frágeis, isso porque o sistema hidrológico cárstico é altamente vulnerável à poluição em decorrência de suas características físicas de drenagem predominantemente vertical e ausência de camadas que filtram a água antes de sua chegada aos aquíferos. Diante disso, o principal objetivo do presente trabalho consistiu em realizar, mediante adaptações necessárias, o diagnóstico físico-conservacionista do ambiente cárstico da bacia do córrego Cana-brava, inserida nos municípios de Aurora do Tocantins e Lavandeira, visando contribuir para um melhor conhecimento do carste no estado do Tocantins, além de servir como suporte à elaboração de diretrizes e estratégias de ação voltadas à preservação ambiental da área de estudo. A metodologia do diagnóstico físico-conservacionista busca diagnosticar a situação real em que se encontram os recursos naturais renováveis em um determinado espaço geográfico e fornece indicativos concretos para o manejo e uso racional de recursos naturais renováveis da bacia hidrográfica. Os resultados obtidos nesta pesquisa apontam a eficiência no uso da metodologia do diagnóstico físico-conservacionista para o ambiente cárstico, uma vez que esta atendeu ao objetivo proposto que consistiu em mensurar o potencial de degradação física de uma bacia hidrográfica, mesmo estando situada em um ambiente cárstico.</p><p><strong>Palavras-chave:</strong> carste, degradação ambiental, bacia hidrográfica.</p><p><strong>Abstract </strong></p><p>Currently it is possible to note a growing increase in the degradation of the environment, which is mainly related to the development of human activities. The karst terrains are environments very fragile, because the hydrological karstic system is highly vulnerable to pollution, due to its physical characteristics of drainage predominantly vertical and absence of layers that filter the water before their arrival to aquifers. In addition, the main objective of this work was to be done through necessary adjustments, the physical diagnostic-conservationist of karstic environment of watershed Cana-brava river, in the municipalities of Aurora do Tocantins and Lavandeira, aiming to contribute to a better understanding of karst in the State of Tocantins, in addition to serving as a support for the development of guidelines and strategies for action targeted at the environmental preservation of the study area. The methodology of physical diagnostic-conservationist (DFC) search diagnose the actual situation of renewable natural resources in a given geographical area and provides concrete indicative for the management and rational use of renewable natural resources of the watershed. The results obtained in this study indicate that the efficiency in the use of the methodology of physical diagnostic-conservationist for the karstic environment, once this methodology has met the objective proposed that consisted in measuring the potential of physical degradation of a watershed, although it is located in a karst environment.</p><p><strong>Keywords:</strong> karst, environmental degradation, watershed.</p>

Identification of glacial meltwater runoff in a karstic environment and its implication for present and future water availability

Glaciers all over the world are expected to continue to retreat due to the global warming throughout the 21st century. Consequently, future seasonal water availability might become scarce once glacier areas have declined below a certain threshold affecting future water management strategies. Particular attention should be paid to glaciers located in a karstic environment, as parts of the meltwater can be drained by underlying karst systems, making it difficult to assess water availability. In this study tracer experiments, karst modeling and glacier melt modeling are combined in order to identify flow paths in a high alpine, glacierized, karstic environment (Glacier de la Plaine Morte, Switzerland) and to investigate current and predict future downstream water availability. Flow paths through the karst underground were determined with natural and fluorescent tracers. Subsequently, geologic information and the findings from tracer experiments were assembled in a karst model. Finally, glacier melt projections driven with a climate scenario were performed to discuss future water availability in the area surrounding the glacier. The results suggest that during late summer glacier meltwater is rapidly drained through well-developed channels at the glacier bottom to the north of the glacier, while during low flow season meltwater enters into the karst and is drained to the south. Climate change projections with the glacier melt model reveal that by the end of the century glacier melt will be significantly reduced in the summer, jeopardizing water availability in glacier-fed karst springs.

Identification of glacial melt water runoff in a karstic environment and its implication for present and future water availability

Glaciers all over the world are expected to continue to retreat due to the global warming throughout the 21st century. Consequently, future seasonal water availability might become scarce once glacier areas have declined below a certain threshold affecting future water management strategies. Particular attention should be paid to glaciers located in a karstic environment, as parts of the melt water can be drained by souterrain karst systems. In this study tracer experiments, karst modeling and glacier melt modeling are combined in order to identify flow paths in a high alpine, glacierized, karstic environment (Glacier de la Plaine Morte, Switzerland) and to investigate current and predict future downstream water availability. Flow paths through the karst underground were determined with natural and fluorescent tracers. Subsequently, tracer results and geologic information were assembled in a karst model. Finally, glacier melt projections driven with a climate scenario were performed to discuss future water availability in the area surrounding the glacier. The results suggest that during late summer glacier melt water is rapidly drained through well-developed channels at the glacier bottom to the north of the glacier, while during low flow season melt water enters into the karst and is drained to the south. Climate change projections reveal that by the end of the century glacier melt will be significantly reduced in the summer, jeopardizing water availability in glacier-fed karst springs.

Phosphorus Speciation in Sediments from Lakes Baihua and Aha with a Typical Karstic Environment, China

This paper reports a study on distribution characteristics of phosphorus and its species in 20 sediments samples from Lakes Baihua and Aha, based on the technique of sequential extraction. Baihua and Aha, two man-made reservoirs, are key drinking-water sources. The results, compatible with local geophysical characteristics, indicate that in sediments from both lakes, the concentrations of inorganic phosphorus (IP) were higher than those of organic phosphorus (OP), and the IP consisted mainly of calcium-bound phosphorus (Ca-P), which may temporarily control phosphorus release. Moreover, the concentrations of total phosphorus (TP) in both lakes sediments were high, thus phosphorus release potential and bioavailability were highly significant. Further statistical analyses revealed significant correlations with two extractable principal components allowing interpretation of possible origins of phosphorus loadings. Furthermore, available remediation measures were briefly evaluated for both lakes in consideration of their distinctive environmental features.