Net drift in an atypical estuary, Long Island Sound
Long Island Sound is an estuary with two-layered flow at the eastern opening to the ocean and a salinity gradient of about 5 parts per thousand between the eastern and western extremes. Tidal currents, wind-driven circulation, and river inflow and fresh water influx are investigated as factors affecting the net drift. Current measurements in eastern Long Island Sound indicate that the tidal circulation features that predominate there do not normally affect the net drift at the New Haven dump site. Drifter returns and a numerical model indicate that seasonal prevailing winds seem to be the primary cause of the net drift in central Long Island Sound.
Variability of currents and horizontal eddy coefficients in Eastern Long Island Sound
Abstract Various circulatory mechanisms within the mesoscale range of tidal flows in Eastern Long Island Sound (LIS) are investigated. Two 13-day time series of current measurements were obtained using three moorings arranged in the form of a triangle. Each mooring contains a single Aanderaa current meter located at a depth of 18 to 20 m. Statistical analysis provides evidence of residual circulation effects of topographic origin in the average flow field. The relative importance and periods of orderly residual patterns and turbulent motions are examined using kinetic energy spectra for the longitudinal and transverse components of the flow. The analyses reveal residual oscillations having nearly the same time scales for all moorings and horizontal turbulent eddies which display a diversity of temporal scales ranging from 0.6 to 2.5 h. Within the high-frequency band of temporal scales the computed spectral curves for longitudinal components generally follow Kolmogorov's ‘ −5/3 law’, while the spectra of transverse components have a slope of approximately −1. A computational technique is described to calculate horizontal eddy coefficients in various directions using the mixing length hypothesis. The coefficients developed using this technique are used to investigate various oscillatory mechanisms in the tidal flows.
Effects of the mineral phase and valence of vanadium on vanadium extraction from stone coal
The influence of roasting on the leaching rate and valence of vanadium was evaluated during vanadium extraction from stone coal. Vanadium in stone coal is hard to be leached and the leaching rate is less than 10% when the raw ore is leached by 4 mol/L H2SO4 at 90°C for 2 h. After the sample is roasted at 900°C for 2 h, the leaching rate of vanadium reaches the maximum, and more than 70% of vanadium can be leached. The crystal of vanadium-bearing mica minerals decomposes and the content of V(V) increases with the rise of roasting temperature from 600 to 900°C, therefore the leaching rate of vanadium increases significantly with the decomposition of the mica minerals. Some new phases, anorthite for example, form when the roasting temperature reaches 1000°C. A part of vanadium may be enwrapped in the sintered materials and newly formed phases, which may impede the oxidation of low valent vanadium and make the leaching rate of vanadium drop dramatically. The leaching rate of vanadium is not only determined by the valence state of vanadium but also controlled by the decomposition of vanadium-bearing minerals and the existence state of vanadium to a large extent.