Deposition of DDE and polychlorinated biphenyls in dated sediments of the Santa Barbara basin

Analysis of dated oceanic sediments from the Santa Barbara Basin of the Southern California Bight has shown that deposition of polychlorinated biphenyls (PCB) began about 1945 and that DDE [1,1-dichloro-2-2-bis(p-chloro-phenyl)ethylene] first appeared in sediments deposited about 1952. Concentrations of both show a progressive increase through 1967; estimated deposition rates (in grams per square meter per year) in 1967 of DDE and PCB were 1.9 x 10(-4) and 1.2 x 10(-4), respectively.     

Solar particle tracks in glass from the surveyor 3 spacecraft

A glass filter from Surveyor 3 has a surface density of approximately 1 x 10(6) tracks per square centimeter from heavy solar flare particles. The variation with depth is best fitted with a solar particle spectrum dN/dE = 2.42 x 10(6) E(-2) [in particles per square centimeter per year per steradian per (million electron volts per nucleon)], where E is the energy and N is the number of particles, from 2 million electron volts per nucleon to approximately 7 million electron volts per nucleon and dN/dE = 1.17 x 10(7) E(-3) at higher energies. Not much difference is observed between 0.5 and 5 micrometers, an indication that there is a lack of track-registering particles below 0.5 million electron volts per nucleon. The Surveyor data are compatible with track results in lunar rocks, provided an erosion rate of approximately 10(-7) centimeter per year is assumed for the latter. The results also suggest a small-scale erosion process in lunar rocks.     

Mississippi deltaic wetland survival: sedimentation versus coastal submergence

Seasonal sedimentation, measured with the aid of artificial marker horizons, was markedly different in deteriorating as compared with stable marshes in the Mississippi River deltaic plain. Deteriorating marshes receive most sediment during storm events, whereas stable marshes receive substantial amounts of sediments during the spring river flood. The deteriorating marshes are accreting at a faster rate (1.5 centimeters per year at streamside, 0.9 centimeter per year at inland areas) than the stable marshes (1.3 centimeters per year at streamside, 0.6 centimeter per year at inland areas). However, relative to local apparent sea-level rise as measured by tide gauges in each area, the deteriorating marshes are not maintaining their intertidal elevation as well as the stable marshes. These results indicate the importance of considering accretion relative to submergence.     

Aluminum-26 and beryllium-10 in greenland ice

Activities of beryllium-10 and aluminum-26 dissolved in 200-year-old Greenland ice were found to be 18.4 (+ 8.4, - 4.8) x 10(-6) and 3.2 +/- 0.9 x 10(-7) disintegration per minute per liter, respectively. From these values and the precipitation rate (30 milliliters of water per square centimeter per year), the production rates of these isotopes are calculated to be 3.6 (+ 1.6, - 0.9) x 10(-2) and 1.7 +/- 0.5 x 10(-4) atom per second * square centimeter. These rates agree with the rates calculated for the production of these isotopes by cosmic rays in the atmosphere. Probably all the Al(26) in the ice is accounted for by such atmospheric production; however, an upper limit for the influx of cosmic dust bearing aluminum-26 is calculated at 3.2 x 10(5) tons per year for Earth. Only upper limits could be found for Al(26) and Be(10) in the undissolved particulate matter in the ice; their addition to the activities in the dissolved material leaves our conclusions unchanged.     

Oxygen consumption in pelagic marine sediments

Measurements in the interstitial waters of pelagic red clay and carbonate ooze sediments in the central equatorial Pacific show that the dissolved oxygen content decreases with depth and levels off at nonzero values. The supply of reactive organic carbon introduced by bioturbation limits oxygen consumption at depth in the sediment. These gradients should produce diffusive fluxes across the sediment-water interface that average about 8.8 x 10(-14) mole per square centimeter per second or 0.08 milliliter per square meter per hour.     

Oceanic electric fields: perception by american eels?

American eels, long-distance migrating fish, consistently exhibited conditioned cardiac deceleration responses to electric fields as small as 0.167 x 10(-2) microampere per square centimeter in water of resistivity 4000 ohm centimeters (6.7 microvolts per centimeter) and 400 ohm centimeters (0.67 microvolt per centimeter). Fewer responses were shown at this current density (0.167 x 10(-2) microampere per square centimeter) in more saline water (40 ohm centimeters, 0.067 microvolt per centimeter) and at a lower current density (0.167 x 10(-3) microampere per square centimeter) in fresh water. Thus, eels have sufficient sensitivity to utilize geoelectric information for orientation.     

Escape of hydrogen from venus

Recombination of O(2)(+) represents a source of fast oxygen atoms in Venus' exosphere, and subsequent collisions of oxygen atoms with hydrogen atoms lead to escape of about 10(7) hydrogen atoms per square centimeter per second. Escape of deuterium atoms is negligible, and the ratio of deuterium to hydrogen should increase with time. It is suggested that the mass-2 ion observed by Pioneer Venus is D(+), which implies a ratio of deuterium to hydrogen in the contemporary atmosphere of about 10(-2), an initial ratio of 5 x 10(-5) and an original H(2)O abundance not less than 800 grams per square centimeter.     

Surface oxidation: a major sink for water on Mars

Surface oxidation irreversibly removes both oxygen and hydrogen from the martian atmosphere at a rate of 10(8) to 10(11) per square centimeter per second. This rate corresponds to a net loss of 10(25) to 10(28) per square centimeter (10(2) to 10(5) grams per square centimeter) of H(2)O, if it is assumed that the loss rate is uniform over geologic time. Heretofore, exospheric escape was considered to be the principal irreversible sink for H(2)O, but the loss rate was estimated to be only 10(8) per square centimeter per second. It is possible that surface oxidation may have had a minor effect on the supply of H(2)O in the regolith and polar caps.     

Apollo 12 lunar samples: trace element analysis of a core and the uniformity of the regolith

Four core and soil samples from Apollo 12 are enriched in a number of trace elements of meteoritic origin to virtually the same degree as Apollo 11 soil. An average meteoritic influx rate of about 4 x 10(-9) gram per square centimeter per year thus seems to be valid for the entire moon. A sample from a light gray, coarse-grained layer in the core resembles lunar basalts in composition, but is enriched by factors of 10(4) to 10(5) in bismuth and cadmium.     

A conducting polymer film stronger than aluminum

Polythiophene (Pth) was electrochemically deposited onto stainless steel substrate from freshly distilled boron fluoride-ethyl ether containing 10 millimoles of thiophene per liter. The free-standing Pth film obtained at an applied potential of 1.3 volts (versus Ag/AgCl) had a conductivity of 48.7 siemens per centimeter. Its tensile strength (1200 to 1300 kilograms per square centimeter) was greater than that of aluminium (1000 to 1100 kilograms per square centimeter). This Pth film behaves like a metal sheet and can be easily cut into various structures with a knife or a pair of scissors.     

Alpha radioactivity of the lunar surface at the landing sites of surveyors 5,6, and 7

Evidence has been obtained for a radioactive deposit on the lunar surface at Mare Tranquillitatis with a total intensity of 0.09 +/- 0.03 alpha disintegration per second per square centimeter. The presence of polonium-210 in amounts that are close to equilibrium indicates a continuous turnover rate of lunar material at this site of less than 0.1 micrometer per year. The lack of such a deposit at two other lunar sites suggests lower local concentrations of uranium there.     

Suppressing drosophila circadian rhythm with dim light

Drosophila larvae were reared and allowed to pupate in continuous bright white light. The pupae were then transferred to a much dimmer blue light. In continuous blue light of intensity below 0.001 erg per square centimeter per second, adult flies emerged in pulses 24.7 hours apart, each pulse occupying about 6 hours. But in continuous light of intensity exceeding 0.1 erg per square centimeter per second, they emerged at a steady rate. This intensity range from effective darkness to effective light is roughly from starlight to moonlight. Inside this range, the emergence peaks broaden for about a week with little change of period.     

Solar constant: first direct measurements

The solar constant was directly measured from an altitude of about 82 kilometers-apparently the first such determination. The total solar intensity was 136.1 milliwatts per square centimeter, or 1.952 calories per square centimeter, per minute-about 2.5 percent less than Johnson's derived value. Energy in the ultraviolet and visible regions (for lambda less than 607 nanometers) was 7.0 percent less than that obtained by integration over Johnson'Scurve; for integral flux of lambda greater than 607 nanometers there was almost perfect agreement. Seven supporting series of measurements from lower altitudes agreed extremely well with these results after correction for atmospheric extinction.     

Use of taylor-aris dispersion for measurement of a solute diffusion coefficient in thin capillaries

A method for the fast measurement of the diffusion coefficients of both small and large molecules in thin capillaries is reported. The method relies on Taylor-Aris dispersion theory and uses standard instrumentation for capillary zone electrophoresis. With this equipment, which consists of thin capillaries (50 to 100 micrometers in inner diameter), an injection system, detector ports, and computer data acquisition, a sample plug is pumped through the capillary at known velocity and the peak dispersion coefficient (D(*)) is measured. With the experimentally measured values of D(*) and flow velocity, and knowledge of the inner diameter of the capillary, the molecular diffusion coefficient (D) can be rapidly derived. For example, for ovalbumin a D value of 0.759 x 10(-6) square centimeter per second is found versus a tabulated value of 0.776 x 10(-6) square centimeter per second (error, 2 percent). For hemoglobin a D value of 0.676 x 10(-6) square centimeter per second is obtained versus a literature value of 0.690 x 10(-6) square centimeter per second (error, 1.5 percent).     

Distribution of hydrogen in the near surface of Mars: evidence for subsurface ice deposits

Using the Gamma-Ray Spectrometer on the Mars Odyssey, we have identified two regions near the poles that are enriched in hydrogen. The data indicate the presence of a subsurface layer enriched in hydrogen overlain by a hydrogen-poor layer. The thickness of the upper layer decreases with decreasing distance to the pole, ranging from a column density of about 150 grams per square centimeter at -42 degrees latitude to about 40 grams per square centimeter at -77 degrees. The hydrogen-rich regions correlate with regions of predicted ice stability. We suggest that the host of the hydrogen in the subsurface layer is ice, which constitutes 35 +/- 15% of the layer by weight.     

Early irradiation of matter in the solar system: magnesium (proton, neutron) scheme

The occurrence of positive and negative (26)Mg anomalies in inclusions of the Allende meteorite is explained in terms of proton bombardment of a gas of solar composition. A significant fraction of (26)Mg in the irradiated gas is stored temporarily in the form of radioactive (26)Al by the reaction (26)Mg(p,n) (26)Al. Proton fluxes of 10(17) to 10(19) protons per square centimeter per year at l million electron volts are inferred. Aluminum-rich materials condensing from the gas phase have positive (26)Mg anomalies, whereas magnesium-rich materials have negative (26)Mg anomalies. The proton flux required to account for the observed magnesium anomalies is used to investigate possible isotopic anomalies in the elements from oxygen to argon. Detectable isotopic anomalies are predicted only for neon. The anomalous neon is virtually pure (22)Ne from (22)Na decay. The predicted amount of anomalous (22)Ne is about 10(-8) cubic centimeter (at standard temperature and pressure) per milligram of sodium.     

Discovery of sodium in the atmosphere of mercury

The spectrum of Mercury at the Fraunhofer sodium D lines shows strong emission features that are attributed to resonant scattering of sunlight from sodium vapor in the atmosphere of the planet. The total column abundance of sodium was estimated to be 8.1 x 10(11) atoms per square centimeter, which corresponds to a surface density at the subsolar point of about 1.5 x 10(5) atoms per cubic centimeter. The most abundant atmospheric species found by the Mariner 10 mission to Mercury was helium, with a surface density of 4.5 x 10(3) atoms per cubic centimeter. It now appears that sodium vapor is a major constituent of Mercury's atmosphere.     

Water on the moon?

If the planets formed at falling temperatures with volatile substances accreting last, the low abundance of lead, bismuth, indium, and thallium in lunar rocks implies an initial water content of no more than 370 grams per square centimeter, and probably much less. The depletion of volatile substances might be expected a priori if the moon accreted as an original satellite of the earth.     

Solid state studies of the radiation history of lunar samples

Particle track densities up to > 3 x 10(9) per square centimeter have been measured in different samples. Rocks 17, 47, 57, and 58 have VH (Z >22) galactic cosmic ray ages of 11, 14, 28, and 13 x 10(6) years, respectively. Rock 57 has a calculated erosion rate of 10(-7) centimeter per year. Near-surface track versus depth data in rock 17 can be fit with solar flare particles that have a differential energy spectrum aE(-3); lunar samples can be used to study the history of solar activity. The uranium in the crystalline rocks occurs principally in small regions <10 to approximately 100 micrometers in size. The (low) thermoluminescence of the fines increases with depth in core 10004. With one possible exception, x-ray studies have not shown pronounced radiation damage effects. The total energy release upon heating is small up to 900 degrees C and occurs in three broad regions.     

X-ray fluorescence: detection of lead in wall paint

An instrument has been developed for the in situ determination of lead on painted surfaces. It utilizes, as a source of gamma rays, radioactive cadmium-109 and its daughter silver-109 (metastable) to excite the K series x-rays of lead, and a solid-state, lithium-drifted germanium detector. The device, which is capable of detecting 0.26 milligram of lead per square centimeter of paint [approximately 3 percent (by weight) of lead in a single coat] beneath ten layers of lead-free paint, has been tested in a preliminary survey of several tenement apartments in New York City.