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"Geomorphology."
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Driving the blue fleet: Temporal variability and drivers behind bluebottle
Physalia physalis, the bluebottle in Australia, are colonial siphonophores that live at the surface of the ocean, mainly in tropical and subtropical waters. P. physalis are sometimes present in large swarms, and with tentacles capable of intense stings, they can negatively impact public health and commercial fisheries. P. physalis, which does not swim, is advected by ocean currents and winds acting on its gas-filled sail. While previous studies have attempted to model the drift of P. physalis, little is known about its sources, distribution, and the timing of its arrival to shore. In this study, we present a dataset with four years of daily P. physalis beachings and stings reports at three locations off Sydney's coast in Australia. We investigate the spatial and temporal variability of P. physalis presence (beachings and stings) in relation to different environmental parameters. This dataset shows a clear seasonal pattern where more P. physalis beachings occur in the Austral summer and less in winter. Cold ocean temperatures do not hinder the presence of P. physalis and the temperature seasonal cycle and that observed in P. physalis presence/absence time-series are out of phase by 3-4 months. We identify wind direction as the major driver of the temporal variability of P. physalis arrival to the shore, both at daily and seasonal time-scales. The differences observed between sites of the occurrence of beaching events is consistent with the geomorphology of the coastline which influences the frequency and direction of favorable wind conditions. We also show that rip currents, a physical mechanism occurring at the scale of the beach, can be a predictor of beaching events. This study is a first step towards understanding the dynamics of P. physalis transport and ultimately being able to predict its arrival to the coast and mitigating the number of people who experience painful stings and require medical help.
Journal Article
Seasonal and Spatial Variations of δsup.13Csub.DIC Values in the Mun River, Northeast Thailand
As an important part of the global carbon cycle, dissolved inorganic carbon (DIC) concentration and its stable carbon isotopic composition (δ[sup.13]C[sub.DIC]) have been used to constrain the sources of DIC in rivers. In this study, we systematically investigated the water chemistry, DIC contents, and δ[sup.13]C[sub.DIC] values in a tropical agricultural river in northeast Thailand. The water temperature ranged from 20.3 to 31.3 °C, and water pH values ranged from 6.4 to 8.4, with seasonal variations. Based on the major ion compositions, the hydro-chemical type of the Mun River water was a unique Na–Ca–Cl–HCO[sub.3] type, controlled by evaporite and silicate weathering. Seasonal variation of DIC concentrations and its carbon isotopic composition was obvious; DIC and δ[sup.13]C[sub.DIC] were significantly lower in the wet season (135 to 3146 μmol/L and −31.0‰ to −7.0‰) compared to the dry season (185 to 5897 μmol/L and −19.6‰ to −2.7‰). A high level of [sup.12]C-enriched DIC/CO[sub.2] from soil respiration and organic matter oxidation may cause the low pH values, δ[sup.13]C[sub.DIC] values, and high partial pressure of CO[sub.2] (pCO[sub.2]) in the middle and lower reaches during the wet/rainy season compared to the dry season. This may be responsible for the seasonal and spatial variations of DIC concentrations and δ[sup.13]C[sub.DIC] values in the Mun River. According to the relationship between pCO[sub.2] and δ[sup.13]C[sub.DIC] values, CO[sub.2] outgassing may be more significant in the dry season, due to the greater influx of groundwater with higher pCO[sub.2] levels; and the rapid CO[sub.2] diffusion into the atmosphere will continuously increase the δ[sup.13]C[sub.DIC] values and decrease pCO[sub.2] levels. These results show that riverine biologic effects and CO[sub.2] outgassing play important roles in the DIC and δ[sup.13]C[sub.DIC] evolution of this typical agriculturally-dominated watershed.
Journal Article
Geomorphology : the mechanics and chemistry of landscapes
\"This textbook provides a modern, quantitative and process-oriented approach to equip students with the tools to understand geomorphology. Insight into the interpretation of landscapes is developed from basic principles and simple models, and by stepping through the equations that capture the essence of the mechanics and chemistry of landscapes. Boxed worked examples and real-world applications bring the subject to life for students, allowing them to apply the theory to their own experience. The book covers cutting edge topics, including the revolutionary cosmogenic nuclide dating methods and modeling, highlights links to other Earth sciences through up-to-date summaries of current research, and illustrates the importance of geomorphology in understanding environmental changes. Setting up problems as a conservation of mass, ice, soil, or heat, this book arms students with tools to fully explore processes, understand landscapes, and to participate in this rapidly evolving field\"--Provided by publisher.
BOOK
Landforms
\"Earth landforms can look very different from place to place. They can be hilly, flat, or mountainous. Landforms can change their shape with earthquakes, volcanoes, floods, mudslides, or erosion. Some of these changes take a long time, and other changes happen quickly. Includes science and reading activities and a word list\"-- Provided by publisher.
Book
Introduction to coastal processes and geomorphology
\"Introduction to Coastal Processes and Geomorphology Written for anyone interested in coastal geomorphology, this is the complete guide to the processes at work on our coastlines and the resulting features seen in coastal systems across the world. Accessible to students from a range of disciplines, the quantitative approach of this book helps to build a solid understanding of wave and current processes that shape coastlines. From sandy beaches to coral reefs, the major coastal features are related to contemporary processes and to sea level changes over the past 25 000 years. Key equations describing these processes and standard methods and instrumentation used to collect measurements are all presented in this wide-ranging overview. Designed to support a one- or two-semester course and grounded in current research, this Second Edition has been substantially updated and rewritten - featuring cutting-edge new topics, insights from new models and technologies, additional global examples and an enhanced package of online teaching materials\"-- Provided by publisher.
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