Raymond L. Chuan

Rates of sulfur dioxide and particle emissions from White Island volcano, New Zealand, and an estimate of the total flux of major gaseous species

Airborne correlation spectrometry (COSPEC) was used to measure the rate of SO2 emission at White Island on three dates, i.e., November 1983, 1230 ± 300 t/d; November 1984, 320 ± 120 t/d; and January 1985, 350 ± 150 t/d (t = metric tons). The lower emission rates are likely to reflect the long-term emission rates, whereas the November 1983 rate probably reflects conditions prior to the eruption of December 1983. The particle flux in the White Island plume, as determined with a quartz crystal microbalance/cascade in November 1983, was 1.3 t/d, unusually low for volcanic plumes. The observed plume particles, as shown from scanning electron microscopy, include halite, native sulfur, and silicates and are broadly similar to other volcanic plumes.Gas analyses from high-temperature volcanic fumaroles collected from June 1982 through November 1984 werde used together with the COSPEC data to estimate the flux of other gas species from White Island. The rates estimated are indicative of the long-term volcanic emission, i.e., 8000–9000 t/d H2O, 900–1000 t/d CO2, 70–80 t/d HCl, 1.5–2 t/d HF, and about 0.2 t/d NH3. The long-term thermal power output at White Island is estimated at about 400 MW.

Halite Particles Injected into the Stratosphere by the 1982 El Chichón Eruption

Halite particles about 2 micrometers in size were collected by a quartz crystal microbalance cascade impactor from the El Chich�n eruption cloud in the lower stratosphere during April and May 1982. These particles are probably derived from the erupted chloride-rich, alkalic magma. Enrichments of hydrogen chloride and increases in optical depolarization in the eruption cloud observed by lidar measurements may reflect the influence of the halite particles. There is evidence that the halite particles reacted with sulfuric acid after about 1 month, releasing gaseous hydrogen chloride, which can influence the catalytic destruction of ozone in the stratosphere.

Fluxes, sizes, morphology and compositions of particles in the Mt. Erebus volcanic plume, December 1983

Use of an airborne quartz crystal microbalance cascade impactor instrument together with a correlation spectrometer has allowed the flux of particles and their size distribution to be determined at Mount Erebus. The plume contributes 21±3 metric tomnes/day of aerosol particles to the Antarctic upper troposphere. The aerosol particles consist of larger (5–25 μm) particles of elemental sulfur and silica, a middle sized group of iron oxides and smaller particles (less than 1 μm) of complex liquids. Unlike many volcanic plumes, the Erebus plume has only a small amount of sulfate particles. The concentrations of particles in the Erebus plumes was 70–370 μm/m3. Limited sampling of the Antarctic atmosphere at 8 km altitude but hundreds of km away from Erebus obtained a few large particles of sulfur and silicates, suggesting a similarity with the Erebus plume. The fallout of these particles occurs slowly over a broad area of the Antarctic continent.

High sensitivity real-time NVR monitor

The use of a temperature-controlled 200-MHz SAW resonator piezoelectric mass microbalance to monitor the mass of nonvolatile residue (NVR) deposited on its surface in real time is reported. The fundamental frequency of this device is mainly dependent on the configuration of the transducers and not on the thickness of the substrate. Therefore, higher operating frequencies can be achieved without reducing the thickness of the crystal. The real-time instrument was integrated onto a conventional stainless steel NVR plate and operated flawlessly over a 14-d period at Kennedy Space Center and successfully measured less than 1 ng/sq cm d NVR contamination. Contamination episodes detected by the instrument were correlated with scheduled activities on the test stand. Under the assumption of a baseline noise level of +/- 2 Hz, the absolute mass lower limit of detection would be 0.065 ng/sq cm. This would enable the detection of a daily NVR deposition rate of less than 0.1 ng/sq cm d.

Emission of elemental gold particles from Mount Erebus, Ross Island, Antarctica

Volcanoes are an important source of gases and aerosols in the atmosphere. Significant quantities of trace elements are emitted as vapor species [Nriagu, 1989; Symonds et al., 1987] and are strongly enriched in the gas relative to the magma [Tazieff and Sabroux, 1983; Crowe et al., 1987]. After eruption the trace elements condense on ash and other particles or they form sublimates and agglomerates. Here we report on the emission of gold (Au) from Mount Erebus, Antarctica. Although the flux of emitted Au is low compared to other volcanoes, crystalline particulate Au has been found in the plume near the crater, in ambient air up to 1000 km from the volcano and in near surface samples. Vapor phase transport of Au may occur as a chloride species and could be an important transport mechanism in crystallizing magmatic intrusions.

Underwater sound attenuator

An apparatus for preventing the transmission of sound in an underwater medium. A resilient housing encloses at least two voids. A first void contains a compliant tube consisting of two T-shaped support structures, each T-shaped support structure supporting a free-bending span designed to resonate at a predetermined frequency. A second void contains a viscous liquid in which metal fibers are suspended. The resilient housing may be surrounded by a rigid cover material which may include means for fastening the apparatus to a surface. The viscous liquid dissipates sound. The compliant tube attenuates the sound waves and decreases the velocity of the sound waves, consequently decreasing the wavelength of the waves.

Fine Particles in the Soufriere Eruption Plume

The size distributions of fine particles measured at tropospheric altitudes in the periphery of the eruption plume formed during the 17 April 1979 eruption of Soufriere Volcano and in the low-level effluents on 15 May 1979 were found to be bimodal, having peak concentrations at geometric mean diameters of 1.1 and 0.23 micrometers. Scanning electron microscopy and energy-dispersive x-ray analysis of the samples revealed an abundance of aluminum and silicon and traces of sodium, magnesium, chlorine, potassium, calcium, and iron in the large-particle mode. The submicrometer-sized particles were covered with liquid containing sulfur, assumed to be in the form of liquid sulfuric acid.

200-MHz surface acoustic wave mass microbalance

The principle of operation of the surface acoustic wave (SAW) piezoelectric crystals used as microgravimetric sensors in mass microbalances is discussed. Special attention is given to a SAW 200-MHz crystal developed for measuring molecular deposition on spacecrafts, whose operating frequency does not depend on the thickness of the crystal. The frequency stability of the 200 MHz SAW device is better than 5 x 10 exp -9, which corresponds to a lower limit-of-detection of 3 x 10 exp -12 g for a signal-to-noise ratio of 3. A block diagram of the 200 MHz SAW mass microbalance and a schematic diagram of SAW resonator are presented together with performance data of this device.

A non-optical real-time particle fallout monitor

The paper describes a size-selective fallout monitor that can be employed to assess the degradation of sensitive optical surfaces as well as facilitate the analysis of particle types. The device combines a vertical elutriator and a quartz crystal microbalance, and only particles greater than a specific size can pass through an upward laminar flow generated in the device. The larger particles cause a frequency shift in the crystal oscillator, thereby permitting the measurement of the fallout associated with the contamination of optical instruments.