Agriculture, meteorology and water quality in Ireland: a regional evaluation of pressures and pathways of nutrient loss to water

peer-reviewedThe main environmental impact of Irish agriculture on surface and ground water quality is the potential transfer of nutrients to water. Soil water dynamics mediate the transport of nutrients to water, and these dynamics in turn depend on agro-meteorological conditions, which show large variations between regions, seasons and years. In this paper we quantify and map the spatio-temporal variability of agro-meteorological factors that control nutrient pressures and pathways of nutrient loss. Subsequently, we evaluate their impact on the water quality of Irish rivers. For nitrogen, pressure and pathways factors coincide in eastern and southern areas, which is reflected in higher nitrate levels of the rivers in these regions. For phosphorus, pathway factors are most pronounced in north-western parts of the country. In south-eastern parts, high pressure factors result in reduced biological water quality. These regional differences require that farm practices be customised to reflect the local risk of nutrient loss to water. Where pathways for phosphorus loss are present almost year-round—as is the case in most of the north-western part of the country—build-up of pressures should be prevented, or ameliorated where already high. In south-eastern areas, spatio-temporal coincidence of nutrient pressures and pathways should be prevented, which poses challenges to grassland management

Measurement of Lande g factor of 5D5/2 state of BaII with a single trapped ion

We present the first terrestrial measurement of the Lande g factor of the 5D5/2 state of singly ionized barium. Measurements were performed on single Doppler-cooled 138Ba+ ions in a linear Paul trap. A frequency-stabilized fiber laser with nominal wavelength 1.762 um was scanned across the 6S1/25D5/2 transition to spectroscopically resolve transitions between Zeeman sublevels of the ground and excited states. From the relative positions of the four narrow transitions observed at several different values for the applied magnetic field, we find a value of 1.2020+/-0.0005 for g of 5D5/2.Comment: 3 figure

Inquiry-Based Learning (IBL) as a Driver of Curriculum: A Staged Approach

Inquiry-based learning provides students with an opportunity to take ownership of their learning while developing important higher order skills necessary for designing innovative solutions to complex modern health problems. In our undergraduate health sciences program, critical thinking, creativity, research skills and innovative thinking are core program learning outcomes, and thus inquiry-based learning is an important pillar of our curriculum. We have taken a staged approach, integrating inquiry-based learning (IBL) into each year of a four-year undergraduate degree program that scaffolds structure and independence to suit undergraduate student needs from the first to third years and culminating in an independent, student-driven honours thesis in the fourth year. In this paper, we share practical IBL strategies that pair with student needs throughout the four-year continuum and highlight strategies to address challenges at each stage of learning

Low-Volume Magmatism Linked to Flank Deformation on Isla Santa Cruz, Galápagos Archipelago, Using Cosmogenic \u3csup\u3e3\u3c/sup\u3eHe Exposure and \u3csup\u3e40\u3c/sup\u3eAr/\u3csup\u3e39\u3c/sup\u3eAr Dating of Fault Scarps and Lavas

Isla Santa Cruz is a volcanic island located in the central Galápagos Archipelago. The island’s northern and southern flanks are deformed by E–W-trending normal faults not observed on the younger Galápagos shields, and Santa Cruz lacks the large summit calderas that characterize those structures. To construct a chronology of volcanism and deformation on Santa Cruz, we employ 40Ar/39Ar geochronology of lavas and 3He exposure dating of fault scarps from across the island. The combination of Ar–Ar dating with in situ-produced cosmogenic exposure age data provides a powerful tool to evaluate fault chronologies. The 40Ar/39Ar ages indicate that the island has been volcanically active since at least 1.62 ± 0.030 Ma (2SD). Volcanism deposited lavas over the entire island until ~ 200 ka, when it became focused along an E–W-trending summit vent system; all dated lavas \u3c 200 ka were emplaced on the southern flank. Structural observations suggest that the island has experienced two major faulting episodes. Crosscutting relationships of lavas indicate that north flank faults formed after 1.16 ± 0.070 Ma, but likely before 416 ± 36 ka, whereas the faults on the southern flank of the island initiated between 201 ± 37 and 32.6 ± 4.6 ka, based on 3He exposure dating of fault surfaces. The data are consistent with a model wherein the northeastern faults are associated with regional extension owing to the young volcano’s location closer to the Galápagos Spreading Center at the time. The second phase of volcanism is contemporaneous with the formation of the southern faults. The expression of this younger, low-volume volcanic phase was likely related to the elongate island morphology established during earlier deformation. The complex feedback between tectonic and volcanic processes responsible for southward spreading along the southern flank likely generated persistent E-W-oriented magmatic intrusions. The formation of the Galápagos Transform Fault and sea-level fluctuations may be the primary causes of eruptive and deformational episodes on Santa Cruz

Time-resolved broadband analysis of slow-light propagation and superluminal transmission of electromagnetic waves in three-dimensional photonic crystals

A time-resolved analysis of the amplitude and phase of THz pulses propagating through three-dimensional photonic crystals is presented. Single-cycle pulses of THz radiation allow measurements over a wide frequency range, spanning more than an octave below, at and above the bandgap of strongly dispersive photonic crystals. Transmission data provide evidence for slow group velocities at the photonic band edges and for superluminal transmission at frequencies in the gap. Our experimental results are in good agreement with finite-difference-time-domain simulations.Comment: 7 pages, 11 figure

Multiscale Random-Walk Algorithm for Simulating Interfacial Pattern Formation

We present a novel computational method to simulate accurately a wide range of interfacial patterns whose growth is limited by a large scale diffusion field. To illustrate the computational power of this method, we demonstrate that it can be used to simulate three-dimensional dendritic growth in a previously unreachable range of low undercoolings that is of direct experimental relevance.Comment: 4 pages RevTex, 6 eps figures; substantial changes in presentation, but results and conclusions remain the sam

Quasiperiodic Tip Splitting in Directional Solidification

We report experimental results on the tip splitting dynamics of seaweed growth in directional solidification of succinonitrile alloys with poly(ethylene oxide) or acetone as solutes. The seaweed or dense branching morphology was selected by solidifying grains which are oriented close to the {111} plane. Despite the random appearance of the growth, a quasiperiodic tip splitting morphology was observed in which the tip alternately splits to the left and to the right. The tip splitting frequency f was found to be related to the growth velocity V as a power law f V^{1.5}. This finding is consistent with the predictions of a tip splitting model that is also presented. Small anisotropies are shown to lead to different kinds of seaweed morphologies.Comment: 4 pages, 7 figures, submitted to Physical Review Letter

Pathways for nutrient loss to water with emphasis on phosphorus

Teagasc wishes to acknowledge the support of the Environmental Research Technological Development and Innovation (ERTDI) Programme under the Productive Sector Operational Programme which was financed by the Irish Government under the National Development Plan 2000-2006.End of project reportThe main objective of this project was to study phosphorus (P) loss from agricultural land under a range of conditions in Ireland, to quantify the main factors influencing losses and make recommendations on ways to reduce these losses. This report is a synthesis of the main conclusions and recommendations from the results of the studies. The final reports from the individual sub-projects in this project are available from the EPA (www.epa.ie).Environmental Protection Agenc