136,021 research outputs found
An Assessment of Nitrogen Leaching from Watersheds included in ICP on Waters (ICP Waters report)
No full textThe importance of nitrate in acidification has been evaluated for 163 sites uncluded in ICP on Waters in 13 countries in Europe and North America. At 63 % of these sites yearly average nitrate concentrations amounted to more than 10 % of the acid non-marine acid anions. This shows that nitrate leakage contributes significantly to acidification at a majority of the ICP sites. High leakage of nitrogen occur only at sites with high nitrogen concentrations in precipitation and high total deposition of nitrogen (wet+dry). 144 ICP sites were classified according to Stoddard's system for stages of nitrogen saturation. Approximately one half of the sites had a high degree of nitorgen saturation (Stage 2 or 3). There was a clear coherence between stage classification and total N depositio
Critical Loads, Target Load Functions and Dynamic Modelling for Surface Waters and ICP Waters Sites (ICP Waters report 83/2006)
No full textCritical load functions (CLF) for ICP Water sites estimated with the FAB model and based on recent data (2000-02) do not differ greatly from those based on earlier data (1992-94/5). The ICP Waters sites in Europe are largely characteristic of the most sensitive waters within the EMEP 50 km grid cell. Target load functions (TLF) require use of a dynamic model. For acidified waters the TLF for sulphur (Smax) is often lower than the CLF, because of time lags in the recovery of catchment soils in response to reduced S deposition. On the other hand the TLF for nitrogen (Nmax) is often higher than the CLF, because most catchments presently are not N-saturated and retain a large fraction of N-deposition. Scientific understanding of processes governing N-retention and loss from catchments remains insufficient and is the major source of uncertainty in modelling acidification of soils and waters. Climate change will also affect the uncertainty with respect to N
Surveillance of adenoviruses and noroviruses in European recreational waters
No full textExposure to human pathogenic viruses in recreational waters has been shown to cause disease outbreaks. In the context of Article 14 of the revised European Bathing Waters Directive 2006/7/EC (rBWD, CEU, 2006) a Europe-wide surveillance study was carried out to determine the frequency of occurrence of two human enteric viruses in recreational waters. Adenoviruses were selected based on their near-universal shedding and environmental survival, and noroviruses (NoV) selected as being the most prevalent gastroenteritis agent worldwide. Concentration of marine and freshwater samples was done by adsorption/elution followed by molecular detection by (RT)-PCR. Out of 1410 samples, 553 (39.2%) were positive for one or more of the target viruses. Adenoviruses, detected in 36.4% of samples, were more prevalent than noroviruses (9.4%), with 3.5% GI and 6.2% GII, some samples being positive for both GI and GII. Of 513 human adenovirus-positive samples, 63 (12.3%) were also norovirus-positive, whereas 69 (7.7%) norovirus-positive samples were adenovirus-negative. More freshwater samples than marine water samples were virus-positive. Out of a small selection of samples tested for adenovirus infectivity, approximately one-quarter were positive. Sixty percent of 132 nested-PCR adenovirus-positive samples analysed by quantitative PCR gave a mean value of over 3000 genome copies per L of water. The simultaneous detection of infectious adenovirus and of adenovirus and NoV by (RT)PCR suggests that the presence of infectious viruses in recreational waters may constitute a public health risk upon exposure. These studies support the case for considering adenoviruses as an indicator of bathing water quality
Average seasonal changes in chlorophyll a in Icelandic waters
No full textThe standard algorithms used to derive sea surface chlorophyll a concentration from remotely sensed ocean colour data are based almost entirely on the measurements of surface water samples collected in open sea (case 1) waters which cover ~60% of the worlds oceans, where strong correlations between reflectance and chlorophyll concentration have been found. However, satellite chlorophyll data for waters outside the defined case 1 areas, but derived using standard calibrations, are frequently used without reference to local in situ measurements and despite well-known factors likely to lead to inaccuracy. In Icelandic waters, multiannual averages of 8-d composites of SeaWiFS chlorophyll concentration accounted for just 20% of the variance in a multiannual dataset of in situ chlorophyll a measurements. Nevertheless, applying penalized regression spline methodology to model the spatial and temporal patterns of in situ measurements, using satellite chlorophyll as one of the predictor variables, improved the correlation considerably. Day number, representing seasonal variation, accounted for substantial deviation between SeaWiFS and in situ estimates of surface chlorophyll. The final model, using bottom depth and bearing to the sampling location as well as the two variables mentioned above, explained 49% of the variance in the fitting dataset
Stabilizing periodic orbits above the elliptic plane in the solar sail 3-body problem
No full textWe consider periodic orbits high above the ecliptic plane in the Elliptic Restricted Three-Body Problem where the third massless body is a solar sail. Periodic orbits above the ecliptic are of practical interest as they are ideally positioned for the year-round constant imaging of, and communication with, the poles. Initially we identify an unstable periodic orbit by using a numerical continuation from a known periodic orbit above the ecliptic in the circular case with the eccentricity as the varying parameter. This orbit is then used to construct a reference trajectory for the sail to track. In addition we illustrate an alternative method for constructing a periodic reference trajectory based on a time-delayed feedback mechanism. The reference trajectories are then tracked using a linear feedback regulator (LQR) where the control actuation is delivered by varying the solar sails orientation. Using this method it is shown that a 'near term' solar sail is capable of performing stable periodic motions high above the ecliptic
Impacts of Air Pollution on Freshwater Acidification under Future Emission Reduction Scenarios; ICP Waters contribution to WGE report (ICP Waters report 108/2011)
No full textThe UNECE Convention on Long-range Transboundary Air Pollution (LRTAP) is currently working on a revision of the Gothenburg protocol. ICP Waters has used the dynamic model MAGIC to evaluate the effects of future deposition scenarios (COB2020 (current legislation), Low*2020, Mid*2020, High*2020, and MFR2020 (maximum technically feasible reduction) on surface waters. These five deposition scenarios are very similar to one another and represent substantial decreases in deposition for the year 2020 relative to the base year 2000. At all sites the modelled results indicate that chemical recovery will continue into the future. At all but the most acid sensitive sites acid neutralising capacity (ANC) will increase to levels above the critical level for biological damage. Additional improvements in water quality can be obtained in the future with emission reductions beyond MFR2020.Norwegian Climate and Pollution Agenc
Letter, [Author unclear] to Paulina T. Merritt
No full textHandwritten letter to Paulina Merritt from an unknown author, October 1, 1876.
Kenneth T. Tinkler
No full text"Kenneth T. Tinkler QABF June 1941 - Oct 1992 [illegible]wkshop sqn. 1RSU Daly Waters 13Sqn - Hughes".Kenneth T. Tinkler QABF [?] June 1941 - October 1992 [illegible]workshop squadron. 1 Repair and Salvage Unit, Daly Waters 13Squadron - Hughes
[T&P Bridge and Flood Waters]
No full textPhotograph of the T&P bridge and surrounding flood waters. In the photograph, a boat is visible floating behind a tree. Handwritten note on reverse: "May 1908 flood waters T&P Bridge remains standing tracks washed out.
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