66 research outputs found

    Fate of rising methane bubbles in stratified waters: How much methane reaches the atmosphere?

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    There is growing concern about the transfer of methane originating from water bodies to the atmosphere. Methane from sediments can reach the atmosphere directly via bubbles or indirectly via vertical turbulent transport. This work quantifies methane gas bubble dissolution using a combination of bubble modeling and acoustic observations of rising bubbles to determine what fraction of the methane transported by bubbles will reach the atmosphere. The bubble model predicts the evolving bubble size, gas composition, and rise distance and is suitable for almost all aquatic environments. The model was validated using methane and argon bubble dissolution measurements obtained from the literature for deep, oxic, saline water with excellent results. Methane bubbles from within the hydrate stability zone (typically below ∌500 m water depth in the ocean) are believed to form an outer hydrate rim. To explain the subsequent slow dissolution, a model calibration was performed using bubble dissolution data from the literature measured within the hydrate stability zone. The calibrated model explains the impressively tall flares (>1300 m) observed in the hydrate stability zone of the Black Sea. This study suggests that only a small amount of methane reaches the surface at active seep sites in the Black Sea, and this only from very shallow water areas (<100 m). Clearly, the Black Sea and the ocean are rather effective barriers against the transfer of bubble methane to the atmosphere, although substantial amounts of methane may reach the surface in shallow lakes and reservoirs

    Riparian Research and Management: Past, Present, Future: Volume 1

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    Fifty years ago, riparian habitats were not recognized for their extensive and critical contributions to wildlife and the ecosystem function of watersheds. This changed as riparian values were identified and documented, and the science of riparian ecology developed steadily. Papers in this volume range from the more mesic northwestern United States to the arid Southwest and Mexico. More than two dozen authors—most with decades of experience—review the origins of riparian science in the western United States, document what is currently known about riparian ecosystems, and project future needs. Topics are widespread and include: interactions with fire, climate change, and declining water; impacts from exotic species; unintended consequences of biological control; the role of small mammals; watershed response to beavers; watershed and riparian changes; changes below large dams; water birds of the Colorado River Delta; and terrestrial vertebrates of mesquite bosques. Appendices and references chronicle the field’s literature, authors, “riparian pioneers,” and conferences

    Breaking the Silence: Providing Authentic Opportunities for Parents to be Heard

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    Within Western society over the past 30 years a vivid picture has emerged of exactly what a ‘good parent’ looks like. This ideal parent works hard in order to contribute to the economic wellbeing of the nation at the same time as having abundant time for the nurture and educational development of their child. This parent does not question or challenge, but rather silently supports the superior knowledge of researchers, policy makers and educationalists. This parent is ‘valued’ as the child’s first educator, yet, we argue in this piece, has no voice. In this literature-based article we explore the silencing of parents within educational systems and look at the possibility of creating more authentic partnerships between them and educational settings. We challenge notions of parental conformity and instead encourage educational cultures where parents are invited to suggest and challenge, inspire and educate. We look at ways of opening positive channels of communication between parents and educationalists, where knowledge and perceptions of quality can be genuinely shared, recognising and respecting the multiple dimensions of school and family life

    Three Years' Use of a Cobalt 60 Unit

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