A rapid-response 2-D drag anemometer for atmospheric turbulence measurements

A rapid response drag anemometer for measuring streamwise and lateral components of horizontal windspeed is described. Theory of operation, design and calibration are discussed with emphasis on the electronic preconditioning of signals and problems associated with using a mechanically resonant system as a sensor. Field comparisons showed half-hourly means and standard deviations of the streamwise component to be within 8% and 5% of respective values obtained from a 3-dimensional sonic anemometer. The lateral component from the drag anemometer was significantly more noisy than that from the 3-D sonic due to induced oscillations arising from vortex shedding. After mechanical and electronic filtering, half-hourly standard deviation comparisons agreed to within 6% for this component. Friction velocities obtained from the drag anemometer in combination with a 1-D sonic, agreed with measurements from the 3-D sonic anemometer to within 4% over a measured range of 0.05 to 1.2 m s^-1     

Are Taxonomic Distinctness measures compliant to other ecological indicators in assessing ecological status?

Assessing the ecological status, a concept implemented in the European Water Framework Directive [EC, 2000. Directive of the European Parliament and of the Council 2000/60/EC establishing a framework for community action in the field of water policy PE-CONS 3639/1/00, p. 72], requires the application of methods capable of distinguishing different levels of ecological quality. The Average Taxonomic Distinctness has been used as tool in this context, and we tested the robustness of Taxonomic Distinctness measures applying it in different scenarios (estuarine eutrophication, organic pollution, and re-colonisation after physical disturbance), analysing simultaneously its compliance to other types of ecological indicators. Results show that, in most of the case studies, only Total Taxonomic Distinctness was relatively satisfactory in discriminating between disturbed situations. Other Taxonomic Distinctness measures have not proved to be more sensitive than other ecological indicators (Shannon-Wiener, Margalef, and Eco-Exergy indices). Therefore, this approach does not seem to be particularly helpful in assessing systems' ecological status with regard to the WFD implementation.     

Dissolution kinetics of fosteritic olivine at 90-150 °C including effects of the presence of CO2

The steady state dissolution rate of San Carlos olivine [Mg_1.82Fe_0.18 SiO₄] in dilute aqueous solutions was measured at 90, 120, and 150 °C and pH ranging from 2 to 12.5. Dissolution experiments were performed in a stirred flow-through reactor, under either a nitrogen or carbon dioxide atmosphere at pressures between 15 and 180 bar. Low pH values were achieved either by adding HCl to the solution or by pressurising the reactor with CO₂, whereas high pH values were achieved by adding LiOH. Dissolution was stoichiometric for almost all experiments except for a brief start-up period. At all three temperatures, the dissolution rate decreases with increasing pH at acidic to neutral conditions with a slope of close to 0.5; by regressing all data for 2 ? pH ? 8.5 and 90 °C ? T ? 150 °C together, the following correlation for the dissolution rate in CO₂-free solutions is obtained: