Vegetation and the atmospheric cycling of mercury

Beyond their role in the cycling of the major elements, carbon, nitrogen, oxygen, etc., little is known about geobiological interactions involving plants with the elements of lower abundance. Plants influence the distribution of volcanic mercury by uptake from the atmosphere and soil fluids, transport to the shoot and re-release as Hg° into the atmosphere. Release rates as high as 2.5 × 10^?4 g.h^?1 per kg are known but even at more typical rates, fluxes far greater than the Environmental Protection Agency calculated U.S. average annual degassing rate of 130 × 10^?6 g.m^?2 should exist. On a global basis, the presence or absence of vegetative cover may be a significant regulator of Hg° transport between land surfaces and the atmosphere.     

Magnetic braking of the Earth's rotation

The Earth's rotation is decelerating at a rate of 8.8×10 exp-20 rad/s. Thus, a leap second is added to the year every two to four years. This deceleration is small, but the Earth weighs 6×10 exp 24 kg. A prony brake that achieves this deceleration would release 5.14×10 exp 11 kW, the equivalent of 514,000 1-GW nuclear power plants. Tides, volcanos, Coriolis-generated ocean currents and winds cannot absorb this much power. This leaves the induction generation which produces the Earth's magnetic field as the most likely absorber of the deceleration power. The efficiency of this inaccessible induction generator cannot be calculated. However, it is thought that correlation of the Earth's deceleration with its 0.09% weakening magnetic field could provide insight into the power generation process     

Spectra of fresh photo-electrons in the Martian atmosphere

In this paper the latest neutral and ionospheric models of the upper Martian atmosphere, created on the Viking data are used. For the calculations of the photoelectron spectra the Hinteregger's measurements of the solar flux together with the theoretical photoelectron distribution are also used.     

Spectroscopic study of plasma parameters for solar active regions and flares

Results are given of the study of active regions and flares by a high resolution Mg XI ion spectra obtained aboard rockets and a satellite. It is shown that there is a noticable similarity in the physical conditions in the plasma of active regions and flares. Plasma of both sources consists okf a thermal component with the temperature T ～ 2.?3.10⁶K for active regions and T ～ 1.5?2.5.10⁷K for flares and in both cases of a relatively small number (～ 1–5%) of suprathermal electrons with an energy E ～ 3–6 kT.     

Microorganisms and biomolecules in space environment experiment ES 029 on Spacelab-1.

Bacterial spores are proper test organisms for studying problems of space biology and exobiology. During the Spacelab 1 mission, studies on the limiting factors for survival of Bacillus subtilis spores in free space have been performed. An exposure tray on the pallet of Spacelab 1 accomodated 316 samples of dry spores for treatment with space vacuum and/or the following selected wavelengths of solar UV: > 170 nm, 220 nm, 240nm, 260nm and 280 nm. After recovery, inactivation, mutation induction, reparability, and photochemical damages in DNA and protein have been studied. The results contribute to the understanding of the mechanisms of increased UV sensitivity of bacterial spores in vacuo and to a better assessment of the chance of survival of resistant forms in space and of interplanetary transfer of life.     

Particle and Joule heating of the neutral polar thermosphere in cusp region using Atmosphere Explorer-C satellite measurements

Simultaneous measurements taken by instruments on the Atmosphere Explorer - C satellite were used to compare electron and proton particle energy deposition, Joule heating, and neutral density perturbations in the region of the cusp.Altitude profiles of Joule heating, electron energy deposition, and electron density are derived using measurements taken by the satellite as input to a computer model. Electric fields are calculated using ion drift measurements. Figures are presented for a representative orbital pass.A peak Joule heating rate of 0.059 Wm^?2 occurred in the cusp region with a peak of 0.025 Wm^?2 in the evening auroral electrojet. Peak volume heating rates corresponding to these regions were 1.4 × 10^?6Wm^?3 and 7.10^?7 Wm^?3, both occurring at an altitude of 115 km. Particle energy deposition was about an order of magnitude less than Joule heating. Large neutral density perturbations are related to regions of heating.     

Forces acting on a foreign particle near a solidification front

The interaction of inert foreign particles and a solid-liquid interface during solidification is considered. The viscous drag on the particle which produces a force on the interface is calculated under general assumptions as well as the disjoining force for small particles and the buoyancy force for large ones.