Abundances and sources of rare-earth elements in the modern volcanogenic hydrothermal systems of Kamchatka

Sources of modern hydrothermal systems are considered on the basis of high-precision REE data on representative samples of characteristic hydrochemical types of hydrothermal systems of the Eastern Volcanic Belt of Kamchatka and data available on modern magmatogenic fluid systems of the Kamchatka, Kuriles, and oceanic rift zones. It was found that modern high-temperature chloride-sodium hydrothermal vents have elevated REE contents and that all considered hydrochemical types of the Kamchatka hydrothermal systems are characterized by similar REE patterns. High REE contents in the hydrothermal vents with pH up to 5.0 show bimodal distribution. Correlations established between La/Yb ratios in the hydrothermal vents of various types and in the igneous rocks of the Eastern Volcanic Belt of Kamchatka are interpreted in genetic terms. A positive correlation was found between rare-earth elements, chlorine and boron contents. It was noted that all considered hydrochemical types show distinct negative europium anomaly, whereas submarine hydrothermal vents of oceanic rift zones are characterized by positive europium anomaly. It was proposed that REE was transported in the hydrothermal vents from apical zones of deep-seated magma chambers containing acid derivatives.     

Near Infrared Observation of Carbon and S Stars with Silicate Feature

We apply the concept of wave quantum theory in an astronomical scale and discuss the periodic distribution of the galaxies red shift. A generalization of the commutation relation is used to write down the wave equation and the redshift spectrum is calculated. This revised version was published online in July 2006 with corrections to the Cover Date.     

Iron(III) accumulations in inland saline waterways,Hunter Valley,Australia: Mineralogy,micromorphology and pore-water geochemistry

Discharge of Fe(II)-rich groundwaters into surface-waters results in the accumulation of Fe(III)-minerals in salinized sand-bed waterways of the Hunter Valley, Australia. The objective of this study was to characterise the mineralogy, micromorphology and pore-water geochemistry of these Fe(III) accumulations. Pore-waters had a circumneutral pH (6.2–7.2), were sub-oxic to oxic (Eh 59–453 mV), and had dissolved Fe(II) concentrations up to 81.6 mg L⁻¹. X-ray diffraction (XRD) on natural and acid-ammonium-oxalate (AAO) extracted samples indicated a dominance of 2-line ferrihydrite in most samples, with lesser amounts of goethite, lepidocrocite, quartz, and alumino-silicate clays. The majority of Fe in the samples was bound in the AAO extractable fraction (Fe^Ox) relative to the Na-dithionite extractable fraction (Fe^Di), with generally high Fe^Ox:Fe^Di ratios (0.52–0.92). The presence of nano-crystalline 2-line ferrihydrite (Fe₅HO₃·4H₂O) with lesser amounts of goethite (α-FeOOH) was confirmed by scanning electron microscopy (SEM) coupled with energy dispersive X-ray analysis (EDX), and transmission electron microscopy (TEM) coupled with selected area electron diffraction (SAED). In addition, it was found that lepidocrocite (γ-FeOOH), which occurred as nanoparticles as little as ∼5 lattice spacings thick perpendicular to the (0 2 0) lattice plane, was also present in the studied Fe(III) deposits. Overall, the results highlight the complex variability in the crystallinity and particle-size of Fe(III)-minerals which form via oxidation of Fe(II)-rich groundwaters in sand-bed streams. This variability may be attributed to: (1) divergent precipitation conditions influencing the Fe(II) oxidation rate and the associated supply and hydrolysis of the Fe(III) ion, (2) the effect of interfering compounds, and (3) the influence of bacteria, especially Leptothrix ochracea.     

Variability in the nutritional value of the major copepods in Cape Cod Bay (Massachusetts, USA) with implications for right whales

The North Atlantic right whale, a seriously endangered species, is found in Cape Cod Bay (Massachusetts, USA) during the winter and early spring. During their residency in these waters, these whales are frequently observed feeding. This study evaluated spatial and temporal changes in the chemical composition (carbon weight and C/N ratio) of the food resource targeted by the right whales in Cape Cod Bay. The three taxa measured (Centropages typicus, Pseudocalanus spp., and Calanus finmarchicus) had highly variable chemical compositions resulting from the different life strategies and from fluctuations in their surrounding environment. The impact of seasonal variability in the energy densities of the food resource of right whales was calculated and compared to the energetic requirements of these whales. Calculations indicated that differences in the nutritional content of the zooplankton prey in Cape Cod Bay could have a considerable effect on the nutrition available to the right whales. Therefore, it is likely that using more precise estimates of the energetic densities of the prey of right whales would lead to a re‐evaluation of the adequacy of the food resource available to these whales in the North Atlantic.     

Evaluating the effect of non-uniform and deficient irrigation—Part I

A method for evaluating the effect of non-uniform and deficient irrigation is presented. The method is based on a deterministic mathematical model that evaluates the effect of the soil water fluctuation in the root zone during the irrigation season on the crop yield.The problem is viewed in conjunction with the management strategy of irrigation water application under the assumption that only shortage of water causes a reduction in yield. The parameters describing the deficit zone of the application pattern, the soil-crop-atmosphere system and the crop response are incorporated in the model. Crop yield predictions are made through the relative water use and a multiplicative and an additive yield functions.A numerical example is used to illustrate the use of the model in sprinkler irrigation practice. The results agree well with those derived from the mathematical model evaluating the irrigation regime and the yield on each square of the irrigated area separately.     

A current meter with intelligent data system, environmentalsensors, and data telemetry

To measure oceanographic parameters such as currents, temperature, conductivity, pressure, and suspended sediment concentrations, two film-recording current meters were upgraded with microprocessor-controlled data recorders and additional sensors. Two telemetry links relay data and allow the in situ operation of the remote instrument to be checked. In one configuration, the bottom-mounted current meter communicated by a 35-m-long wire to a small surface spar buoy, and then by a packet radio link to a nearby ship. In another development, the current meter relays data to a controller and buoyant data capsule on the bottom instrument package. The controller collects and processes the data from the current meter and periodically transfers these processed data to a data capsule and releases it. When released, the capsule rises to the surface and transmits its data to shore via the ARGOS satellite, while acting as a satellite tracked drifter     

Acoustic Doppler current profiler performance in near surface andbottom boundaries

The authors discuss the current measurement accuracy of the RD Instruments 1200-kHz acoustic Doppler current profiler (ADCP) in the near surface and bottom boundaries. Data are presented from tests. In the first series of tests, an ADCP was mounted on a bottom sled in an upward looking mode. The sled was towed at known speeds with and without surface waves. Additionally, tests were conducted with several acoustic baffle designs installed in the transducer head. The 1200-kHz ADCP has the ability to accurately measure mean currents in a dynamic wave induced flow field. Sidelobes can bias the measurements at 85% of the range when bottom or surface boundaries are present. The amount of bias is strongly dependent on surface wave characteristics. Sidelobe bias can be eliminated with a properly designed baffle system. The profilers have the ability to measure wave particle velocities with a properly configured system