The Carbon Isotope Organic Geochemistry of Early Ordovician Rocks from the Annascaul Formation, County Kerry

Ireland is well known to geologists as containing some of the thickest successions of Early Ordovician (485-470 Ma; Walker et al. 2012) sedimentary rocks in the world. The carbon stable isotope compositions (δ13C value) of similarly aged rocks have been reported for only very few places in the world (i.e., Argentina, southern China, and southern France), and no such analyses have been performed on the Early Ordovician, organic-rich rocks of Ireland. Here we report the δ13C values of bulk organic material and organic isolates recovered from the Annascaul Formation of Southwestern Ireland. Members of the Annascaul Formation spanning the Early Ordovician were sampled at multiple sites within five localities on the Dingle Peninsula, County Kerry. Mean bulk organic δ13C values for the organic matter within rocks of the Farranacarriga, Tinal, Illaunglass, Bealacoon, and Killelton Members ranged from -28.7‰ (Farranacarriga) to -22.1‰ (Illaunglass); the average δ13C values of organics isolated from the Farranacarriga and Bealacoon Members were -29.0 and -28.4‰, respectively. No statistical difference was observed between the δ13C value of isolates and the δ13C value of bulk sediment from which organics had been isolated (P-0.85, Farranacarriga, n-6; P-0.81, Bealacoon, n-5; paired t-test). The δ13C values we present here agree well with the previously published δ13C values for Early Ordovician organic carbon (average = -28.4, -25.4, -25.5‰) from Argentina, southern China, and southern France (respectively). Our new data from the Annascaul Formation are ∼3.3‰ higher than the average value reported for δ13C values of organic matter of marine origin for the same period, raising the possibility that terrestrial bryophytes (or other terrestrial photosynthesizers) contributed to these Early Ordovician sediments. Further equivocal evidence is provided by the abundant organic macerals found within the Farranacarriga Member with possible vitrinite origin. The δ13C values of palynomorphsized organic isolates from the Annascaul Formation reflect a marine origin for these organisms, consistent with their previous identification as acritarchs. Given the recognition of the earliest thalloid macrofossils and land-plant cryptospores in the Middle Ordovician sediments of the Appalachian basin (USA) and Argentina, respectively, our results highlight the Early-Middle Ordovician boundary as a potentially crucial time of terrestrial ecosystem expansion and development

Rotating biological contactors : a review on main factors affecting performance

Rotating biological contactors (RBCs) constitute a very unique and superior alternative for biodegradable matter and nitrogen removal on account of their feasibility, simplicity of design and operation, short start-up, low land area requirement, low energy consumption, low operating and maintenance cost and treatment efficiency. The present review of RBCs focus on parameters that affect performance like rotational speed, organic and hydraulic loading rates, retention time, biofilm support media, staging, temperature, influent wastewater characteristics, biofilm characteristics, dissolved oxygen levels, effluent and solids recirculation, stepfeeding and medium submergence. Some RBCs scale-up and design considerations, operational problems and comparison with other wastewater treatment systems are also reported.Fundação para a Ciência e a Tecnologia (FCT

Assessing Fuzzy Cognitive Mapping as a participatory and interdisciplinary approach to explore marine microfiber pollution

Fuzzy Cognitive Mapping (FCM) is a participatory modelling tool used to explore complex systems by facilitating interdisciplinary cooperation and integrating a variety of knowledge systems. Here FCM was used to explore marine microfiber pollution. Through individual interviews with representatives from the research, industry, water and environmental sectors, five stakeholder FCMs were developed and used to produce an aggregated community FCM in a stakeholder workshop. Stakeholder FCMs and the revised community FCM were used to compute how the modelled system reacted to changes under two scenarios developed during the stakeholder workshop; (i) Green Shift and (ii) increased textile consumption and production. Significant differences were observed in scenario results from the stakeholder-based models and the community-based model. For societal challenges characterized by unknowns around the problem and potential solutions, inclusion of a variety of knowledge systems through FCM and deliberation processes contribute to a more holistic picture of the system and its uncertainties

The transitional climate of the late Miocene Arctic: Winterdominated precipitation with high seasonal variability

© 2017 Geological Society of America. The late Miocene (11.6-5.3 Ma) was an important transitional period following the greenhouse conditions of the Eocene. In order to gain insight into the Arctic paleoclimate of the time, we performed high-resolution intraring δ13C analyses on fossil wood collected from the late Miocene Khapchansky sediments of northeastern Siberia (~69°N). From these data we quantified the ratio of summer to winter precipitation (Ps/Pw) and compared it to current values for the region determined from modern wood samples and instrumental records. We observed much greater frequency of winter-dominated precipitation (Ps/Pw \u3c 1) and much greater variability in Ps/Pw during the Miocene than today. Specifically, years with Ps/Pw \u3c 1 occurred three times more often, and years with at least three times as much precipitation in summer or winter (0.33 \u3c Ps/Pw \u3c 3.0) occurred approximately twice as often during the Miocene than today. We attribute the high interannual variability in precipitation to an inconsistent moisture source associated with the relatively unstable and incomplete ice cover in the Arctic Ocean during the late Miocene. Our result highlights the potential for enhanced variability in Arctic precipitation in response to Arctic sea ice decline caused by anthropogenic, CO2-induced warming

Megafaunal isotopes reveal role of increased moisture on rangeland during late Pleistocene extinctions

The role of environmental change in the late Pleistocene megafaunal extinctions remains a key question, owing in part to uncertainty about landscape changes at continental scales. We investigated the influence of environmental changes on megaherbivores using bone collagen nitrogen isotopes (n = 684, 63 new) as a proxy for moisture levels in the rangelands that sustained late Pleistocene grazers. An increase in landscape moisture in Europe, Siberia and the Americas during the Last Glacial–Interglacial Transition (LGIT; ~25–10 kyr bp) directly affected megaherbivore ecology on four continents, and was associated with a key period of population decline and extinction. In all regions, the period of greatest moisture coincided with regional deglaciation and preceded the widespread formation of wetland environments. Moisture-driven environmental changes appear to have played an important part in the late Quaternary megafaunal extinctions through alteration of environments such as rangelands, which supported a large biomass of specialist grazers. On a continental scale, LGIT moisture changes manifested differently according to regional climate and geography, and the stable presence of grasslands surrounding the central forested belt of Africa during this period helps to explain why proportionally fewer African megafauna became extinct during the late Pleistocene.M. Timothy Rabanus-Wallace, Matthew J. Wooller, Grant D. Zazula, Elen Shute, A. Hope Jahren, Pavel Kosintsev, James A. Burns, James Breen, Bastien Llamas, and Alan Coope