2,389 research outputs found

    Effect of Agricultural Practices on Nitrate Leaching

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    Teagasc wishes to acknowledge with gratitude funding from the 2000-2006 EPA RTDI programme in financing this research project.End of project reportA farm-scale study, carried out at Teagasc, Moorepark (Curtin’s farm), examined the effect of four managements (treatments) on nitrate-nitrogen (NO3-N) leaching over the period 2001-`05. Leaching was measured in these treatments: (T1) plots receiving dirty water and N fertilizer which were grazed; (T2) 2-cut silage and grazing plots receiving slurry and fertilizer N; (T3) grazed plots receiving fertilizer N and (T4) 1-cut silage and grazing plots receiving slurry and fertilizer N. The soil is a free-draining sandy loam overlying Karstic fissured limestone. The mean direct N inputs (kg/ha) for T1-T4 in 2001-`04 were 311, 309, 326, 331, respectively, with stocking rates (LU/ha) of 2.12 - ~2.47. Eight ceramic cups per plot, in 3 replicate plots of each treatment, were used to collect water, on a weekly basis, from 1.0 m deep using 50 kPa suction. There were 33, 37, 26 and 24 sampling dates in the 4 years, respectively. The NO3-N and NH4-N concentrations (mg/l) were determined in the water samples. The annual average and weekly concentration of these parameters was statistically analysed for all years, using a repeated measures analysis. The aggregated data were not normally distributed. There was an interaction between treatment and year (p<0.001). Significant differences (p=0.05) in NO3-N concentrations showed between the treatments in years 1, 2, 4 but not in year 3. For the NH4-N data there was no interaction between treatment and year, p=0.12, or main effect of treatment, p=0.54 but there were differences between years, p=0.01. Mean weekly concentrations were analysed separately for each year. For NO3-N, in years 1, 2 and 4 there was an interaction between treatment and week (p<0.001). With NH4-N, there was an interaction between treatment and week in all 4 years. Dirty water was significantly higher than grazed and 1 cut silage in NO3-N concentrations in year 1; in year 2, dirty water and 2 cut silage were significantly higher than the other treatments while in year 4, dirty water and grazed were significantly higher than the other two treatments. The overall four-year weighted mean NO3-N and NH4-N concentrations were 8.2 and 0.297 mg/l. The NCYCLE (UK) model was adapted for Irish conditions as NCYCLE_IRL. The NCYCLE empirical approach proved to be suitable to predict N fluxes from Irish grassland systems in most situations. Experimental data appeared to agree quite well, in most cases, with the outputs from NCYCLE_IRL. The model was not capable of predicting data from some of the leaching experiments, which suggests that the observed leaching phenomena in these experiments could be governed by non-average conditions or other parameters not accounted for in NCYCLE_IRL. An approach that took into account denitrification, leaching and herbage yield would probably explain the differences found. NCYCLE_IRL proved to be a useful tool to analyse N leaching from grazed and cut grassland systems in Ireland.Environmental Protection Agenc

    Range limitation of the Peaks of Otter salamander (Plethodon hubrichti) due to competition with the eastern red-backed salamander (Plethodon cinereus) in sympatry

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    The Peaks of Otter salamander, Plethodon hubrichti, is a montane species found at altitudes above 442 m within a 117 km2 area of the Blue Ridge Mountains in central Virginia, USA. In areas where this species is sympatric with the eastern red-backed salamander (Plethodon cinereus) it seemed likely that P. hubrichti populations were either depressed or eliminated. The habitability of areas beyond the current range boundaries for P. hubrichti is supported by several disjunct populations in areas sympatric with P. cinereus. From 2009 to 2012 we tested whether P. hubrichti was negatively impacted by competition with P. cinereus by removing P. cinereus from treatment plots at three sympatric field locations. The number of surface-active (SA) P. hubrichti increased significantly more on treatment plots than on corresponding reference plots, whereas the number of SA P. cinereus decreased significantly more on treatment plots than on reference plots. The removal of every one P. cinereus from the treatment plots led to an increase of 0.69 P. hubrichti. These results emphasise the importance of conserving mature hardwood forests along the perimeter of the P. hubrichti distribution, where it is sympatric with P. cinereus, so as to prevent future range contraction of this vulnerable species

    Efficiency Analysis of Energy Networks : An International Survey of Regulators

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    Incentive regulation for networks has been an important part of the reform agenda in a number of countries. As part of this regulatory process, incentives are put in place to improve the cost efficiency of network companies by rewarding good performance relative to a pre-defined benchmark. The techniques used to establish benchmarks are central to the efficiency improvements that are ultimately achieved. Much experience has been gained internationally in the application of benchmarking techniques and we now have a solid understanding of the main indicators of best practice. What we are lacking is a more complete understanding of the factors that influence choice of methods by regulators. In this paper, we present the results of an international survey of energy regulators in 40 countries conducted electronically between June and October 2008. Regulators from European, Australasian and Latin American countries are represented in the survey. Our results show that benchmarking techniques are now widespread in the regulation of gas and electricity networks. Best practice, however, is limited to a small number of regulators. We conclude by summarising existing trends and offering some recommendations on overcoming barriers to best practice efficiency analysis

    Models of planetary rings

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    The Voyager occultations provide several uniform and high quality data sets for Saturn, Uranus, and Neptune. These data are intercompared, and theoretical models for the particle sizes and the particle transport are developed. The major topics covered include: ring size distribution, torques and resonances, and satellite wakes

    Effect of an agri-environmental measure on nitrate leaching from a beef farming system in Ireland

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    peer-reviewedAgricultural nitrogen (N) management remains a key environmental challenge. Improving N management is a matter of urgency to reduce the serious ecological consequences of the reactive N. Nitrate (NO3−–N) leaching was measured under suckler beef production systems stocked at two intensities: (1) intensive, 210 kg organic N ha−1 with two cut silage harvests; and (2) rural environmental protection scheme (REPS), 170 kg organic N ha−1 with one cut silage harvest. Three replicate plots of each treatment were instrumented with ceramic cups (8 per plot), randomly placed within each plot at a depth of 1 m to collect soil solution for NO3−–N at 50 kPa suction to collecting vessels one week prior to sampling. Samples were taken on a total of 53 sampling dates over 3 winter drainage periods (2002/03, 2003/04 and 2004/05). Over the course of the experiment the mean annual soil solution NO3−–N concentration exceeded the MAC twice out of 15 means (5 treatments over 3 years). The REPS grazing and silage sub treatments had significantly lower mean annual soil solution total oxidized N (TON) concentrations than the respective intensive treatments in years 2 and 3. Annual total NO3−–N losses over the three years in intensive and REPS systems ranged from 55 to 71 and 15 to 20 kg N ha−1, respectively. Mean N surpluses in intensive and REPS systems were 210 and 95 kg ha−1, respectively with the corresponding mean N inputs of 272 and 124 kg N ha−1. The reduction in N inputs under the REPS system results in lower N leaching losses and contributed to a significant reduction in pressures on water quality

    Towards a flexible Decision Support Tool for MSY-based Marine Protected Area design for skates and rays

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    Peer-reviewed Paper. This is a pre-copyedited, author-produced version of an article accepted for publication in ICES Journal of Marine Science following peer review. The version of record Dedman, S., Officer, R., Brophy, D., Clarke, M., & Reid, D. G. (2017). Towards a flexible Decision Support Tool for MSY-based Marine Protected Area design for skates and rays. Ices Journal of Marine Science, 74(2), 576–587. https://doi.org/10.1093/icesjms/fsw147 is available online at: https://academic.oup.com/icesjms/article/74/2/576/2669563 & https://doi.org/10.1093/icesjms/fsw147.It is recommended that demersal elasmobranchs be managed using spatial proxies for Maximum Sustainable Yield. Here we combine escapement biomass—the percentage of the stock which must be retained each year to conserve it—with maps of predicted Catch Per Unit Effort (CPUE) of four ray species [cuckoo (Leucoraja naevus), thornback (Raja clavata), blonde (Raja brachyura), and spotted (Raja montagui)], created using Boosted Regression Tree modelling. We then use a Decision Support Tool to generate location and size options for Marine Protected Areas to protect these stocks, based on the priorities of the various stakeholders, notably the minimisation of fishing effort displacement. Variations of conservation/fishing priorities are simulated, as well as differential priorities for individual species, with a focus on protecting nursery grounds and spawning areas. Prioritizing high CPUE cells results in a smaller closed area that displaces the most fishing effort, whereas prioritizing low fishing effort results in a larger closed area that displaces the least fishing effort. The final result is a complete software package that produces maps of predicted species CPUE from limited survey data, and allows disparate stakeholders and policymakers to discuss management options within a mapping interface

    Classification of accelerometer wear and non-wear events in seconds for monitoring free-living physical activity

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    OBJECTIVE: To classify wear and non-wear time of accelerometer data for accurately quantifying physical activity in public health or population level research. DESIGN: A bi-moving-window-based approach was used to combine acceleration and skin temperature data to identify wear and non-wear time events in triaxial accelerometer data that monitor physical activity. SETTING: Local residents in Swansea, Wales, UK. PARTICIPANTS: 50 participants aged under 16 years (n=23) and over 17 years (n=27) were recruited in two phases: phase 1: design of the wear/non-wear algorithm (n=20) and phase 2: validation of the algorithm (n=30). METHODS: Participants wore a triaxial accelerometer (GeneActiv) against the skin surface on the wrist (adults) or ankle (children). Participants kept a diary to record the timings of wear and non-wear and were asked to ensure that events of wear/non-wear last for a minimum of 15 min. RESULTS: The overall sensitivity of the proposed method was 0.94 (95% CI 0.90 to 0.98) and specificity 0.91 (95% CI 0.88 to 0.94). It performed equally well for children compared with adults, and females compared with males. Using surface skin temperature data in combination with acceleration data significantly improved the classification of wear/non-wear time when compared with methods that used acceleration data only (p<0.01). CONCLUSIONS: Using either accelerometer seismic information or temperature information alone is prone to considerable error. Combining both sources of data can give accurate estimates of non-wear periods thus giving better classification of sedentary behaviour. This method can be used in population studies of physical activity in free-living environments
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