Biogeochemical Zones Within a Macrotidal,Dry-Tropical Fluvial-Marine Transition Area: A Dry-Season Perspective

The Fitzroy River delivers large amounts of nutrients and fine sediments to Keppel Bay (contiguous with the Great Barrier Reef Lagoon) during intermittent flow events. This study explores sources, forms and transformations of nutrients in Keppel Bay, and develops a functional process zonation that integrates seabed geochemistry and water column nutrient characteristics which are controlled by suspended sediment. The water column and seabed properties were investigated over two dry seasons, with supplementary core incubations taken to measure carbon decomposition rates and nutrient fluxes. Keppel Bay can be divided into three zones, the: zone of maximum resuspension (ZMR); coastal transitional zone (CTZ); and blue water zone (BWZ). Mineralisation of predominantly terrestrial organic matter occurs in the ZMR where nutrient uptake by phytoplankton is light limited. The CTZ and BWZ had higher light penetration and phytoplankton growth was likely limited by N and P, respectively. The identified zones conform to the bathymetry and hydrodynamic characteristics of the bay, allowing for the development of an integrated conceptual model accounting for the benthic and pelagic biogeochemical processes. Recognition of these different zones shows that considerable variation in benthic and water column properties is possible within a small system with the bathymetric and hydrodynamic characteristics of the fluidized bed reactor.     

Multi-zone fusion crust formation and classification of the 2004 Auckland meteorite (L6, S5, and W0)

On June 12, 2004, a meteorite passed through Earth's atmosphere and landed under the television in the living room of a house in Auckland, New Zealand. Textural characteristics, the chemistry of olivine (Fa_23–24) and orthopyroxene (Fs_20.7), and the bulk rock triple oxygen isotopes (δ¹⁷O + 3.1; δ¹⁸O + 4.2‰) from the interior of the completely unweathered (W0) 1.3 kg meteorite, hereafter referred to as Auckland, suggest it to be a strongly metamorphosed fragment from the interior of a low iron ordinary chondrite (L6) parent asteroid. The occurrence of maskelynite but shock fracturing of olivine and pyroxene indicates Auckland experienced extreme shock metamorphism (S5), likely during Ordovician fragmentation of the asteroid parent. The fusion crust consists of three zones: (1) an innermost zone containing narrow Fe-Ni-S-bearing veins that migrated along pre-existing shock fractures in olivine and pyroxene; (2) a middle zone in which the meteorite partially melted to form a silicate glass and immiscible blebs of metal and troilite, and is accompanied by unmelted silicate minerals; and (3) an approximately 0.1 mm wide vesicular-rich outermost layer that largely melted, volatilizing sulfides, before quenching to form glass and olivine. Oxygen isotope values of the bulk rock and/or maskelynite of melted rim and modified substrate are 2–3‰ greater than the meteorite interior and indicate that up to 19% of terrestrial atmospheric O₂ was incorporated into the fusion crust during the formation. The fusion crust migrated inwards as ablation occurred, enabling melting, migration, and re-precipitation ± loss of sulfide and metal components, with the prominent glassy rim therefore forming from an already chemically modified zone.     

Adaptation to climate change in glaciated mountain regions

Understanding of the human dimensions of climate change (HDCC) in glaciated mountain regions is limited by a deficit in systematically collated information on where, to what stressors, by whom, at what scale, and with what effect adaptation is occurring. This paper presents a systematic literature review of the recent English language peer-reviewed scholarship on adaptation in glaciated mountain regions. 4050 potentially relevant articles were examined, with 36 included for full review. Results indicate that scholarly investigation into adaptation in glaciated mountains is presently limited to only 40 % of countries with alpine glaciation. Seventy-four discrete adaptation initiatives were identified, with most occurring in Peru (28 %), Nepal (22 %) and India (17 %). Many documented adaptations were initiated in response to intersecting stressors related to cryospheric change and socio-economic development; were autonomous and initiated in reaction to experienced climatic stimuli; and were carried out at the individual, family, or community scale. The study contributes to an emerging literature tracking on-the-ground adaptation processes and outcomes, and identifies a need to raise the profile of human adaptation in glaciated mountain regions within the HDCC scholarship. A research agenda for addressing key knowledge gaps and questions is developed, providing a framework for future investigation.     

Oral histories in meteoritics and planetary science—XXV: Vagn F. Buchwald

Vagn Buchwald (Fig.  1 ) was born in Copenhagen where he attended school and college. Then after 18 months of military service, he assumed a position at the Technical University of Copenhagen. A few years later, he was presented with a piece of the Cape York meteorite, which led to an interest in iron meteorites. Through a campaign of informed searching, Vagn found the 20 ton Agpalilik meteorite (part of the Cape York shower) on 31st July 1963 and by September 1967 had arranged its transport to Copenhagen. After sorting and describing the Danish collection, which included application of the Fe‐Ni‐P phase diagram to iron meteorite mineralogy, Vagn was invited to sort and describe other iron meteorite collections. This led to a 7 yr project to write his monumental Handbook of Iron Meteorites. Vagn spent 3 yr in the United States and visited most of the world's museums, the visit to Berlin being especially important since the war had left their iron meteorites in bad condition and without labels. During a further decade or more of iron meteorite research, he documented natural and anthropomorphic alterations experienced by iron meteorites, discovered five new minerals (roaldite, carlsbergite, akaganeite, hibbingite, and arupite); had a mineral (buchwaldite, NaCaPO₄) and asteroid (3209 Buchwald 1982 BL1) named after him; and led expeditions to Chile, Namibia, and South Africa in search of iron meteorites and information on them. Vagn then turned his attention to archeological metal artifacts. This work resulted in many papers and culminated in two major books on the subject published in 2005 and 2008, after his retirement in 1998. Vagn Buchwald has received numerous Scandinavian awards and honors, and served as president of the Meteoritical Society in 1981–1982.     

Ice caps existed throughout the Lateglacial Interstadial in northern Scotland

We constrain, in detail, fluctuations of two former ice caps in NW Scotland with multibeam seabed surveys, geomorphological mapping and cosmogenic ¹⁰Be isotope analyses. We map a continuous sequence of 40 recessional moraines stretching from ～10 km offshore to the Wester Ross mountains. Surface‐exposure ages from boulders on moraine ridges in Assynt and the Summer Isles region show that substantial, dynamic, ice caps existed in NW Scotland between 13 and 14 ka BP. We interpret this as strong evidence that large active glaciers probably survived throughout the Lateglacial Interstadial, and that during the Older Dryas period (ca. 14 ka BP) ice caps in NW Scotland were thicker and considerably more extensive than in the subsequent Younger Dryas Stadial. By inference, we suggest that Lateglacial ice‐cap oscillations in Scotland reflect the complex interplay between changing temperature and precipitation regimes during this climatically unstable period (ca. 15–11 ka BP). © Natural Environment Research Council (NERC) copyright 2008. Reproduced with the permission of NERC. Published by John Wiley & Sons, Ltd.     

Livelihoods and co-management in the Tam Giang lagoon,Vietnam

The Tam Giang – Cau Hai lagoon is a microcosm of the complex social-ecological challenges experienced in similar systems throughout Southeast Asia. Intensification and rapid change in livelihood strategies (production and gear type) have increased conflict and placed a significant strain on aquatic resources in the lagoon. Such changes are compounded by near-shore agricultural development and urbanization. In the long-term, resolving livelihood conflicts and sustaining ecosystems will require a shift in the planning and management model from one that is top-down and enforcement driven, to one involving greater decision making and management authority at the local level. Drawing on experiences with a long-term action research process in the lagoon, this paper examines the challenges and opportunities of implementing a co-management approach. Of particular focus is the growing recognition among authorities of the value of engaging local fishers and fish farmers in participatory process to resolve complex livelihood challenges, and the development of local management bodies (newly formed Fishing Associations) as a basis for emerging co-management of aquatic resources.     

Laser Ablation (U-Th-Sm)/He Dating of Zircons: Analytical Age Bias and its Consequence for Studying Detrital Zircon Populations

The in situ (U-Th-Sm)/He and U/Pb laser-ablation double-dating procedure is a valuable method that can provide a large dataset relatively efficiently in contrast with conventional bulk helium thermochronometry. In this study, we evaluate the potential age error associated with the double ablation procedure and report the in situ (U-Th-Sm)/He double-ablation dating of 249 zircons from the Fish Canyon Tuff locality. With LA-ICP-MS pseudo-depth profiling and 3D numerical modelling, we show that the concentric double-ablation procedure in minerals with U-Th-Sm zoning can generate a significant (U-Th-Sm)/He age error (positive or negative), resulting in over-scattering and/or an offset of the mean age. Pseudo-depth profiling is insufficient to predict the individual age error, partly because of the superimposed ablations. To evaluate the consequence of this inherent bias, we confront a synthetic age distribution to the error expected for U-Th-Sm zoned zircons analysed with double-ablation (U-Th-Sm)/He thermochronometry. As expected, a strong age bias causes the spreading of peak ages, downgrading the original signal. Yet, the throughput of the ablation-based method can allow intra- and inter-sample peak age identification and comparison, and the coupling of (U-Th-Sm)/He and U/Pb ages extends our ability to deconvolute a multimodal age spectrum.