Herbert L. Volchok

Trace metals in atmospheric deposition: A review and assessment

Abstract Information on nineteen metals in atmospheric deposition potentially toxic to humans and other organisms was evaluated to conclude if metal concentrations are increasing in atmospheric deposition and if these concentrations threaten human or organism health. On the basis of rates of emission, atmospheric concentrations, and known temporal trends in deposition, Ag, Cd, Cu, Pb, Sb, Se and Zn can be expected to show the greatest increases due to human activity with little or no increases expected for Co, Mn, Ni and Tl. The limited data available supported these expectations. In some cases, dry fallout was found to be significant relative to wet deposition. Of the metals studied only As, Hg, Se and possibly Cd are in the vapor phase in the atmosphere. Relative to the impact of these increased concentrations, Hg and Pb are now being deposited in some areas at levels toxic to humans and Cd, Cu, Hg, Pb and Zn at levels toxic to other organisms.

Fallout radionuclides in the Pacific Ocean: Vertical and horizontal distributions, largely from GEOSECS stations

Abstract From GEOSECS stations, largely, the 1974 distributions of Pu and of 137 Cs are described in the Pacific Ocean north of about 20°S latitude. Changes in some of these distributions are described from 1978 cruises by the authors. The Pacific exhibited, everywhere, a shallow subsurface layer of Pu-rich water with its concentration maximum at about 465 m in 1974; over a large portion of the central North Pacific a second layer of Pu-labelled water, less concentrated than the shallow layer, lay just above the bottom. Similar features were not observed in the case of 137 Cs. The inventories of both Pu and 137 Cs in the water column at most 1974 stations are substantially greater than those to be expected from world-wide fallout alone; these inventory excesses appear to be attributable to close-in fallout, but only if the ratio Pu/ 137 Cs in this source was much higher than in world-wide fallout. The North Pacific mean ratio of the inventories is 2.2 times that observed in world-wide fallout. Resolubilization of Pu both from sinking particles and from sediments explains peculiarities of its depth distributions. There is little evidence for tracer movement by sliding downward along density surfaces; 137 Cs appears to have moved to depth by downmixing at the edge of the Kuroshio, and then moved horizontally and upward alongσ t contours. The shallow Pu-rich layer shows no coordination with density, salinity or O 2 isopleths. The deep Pu-rich layer is restricted to a narrow range of O 2 concentrations that confirm its origin in the Aleutian Trench and rapid spread southward and laterally. Near-bottom circulation processes have been much more active than here-to-fore described.

Spiked sample standards; Their uses and disadvantages in analytical quality control

Abstract Standard samples, that is matrices containing precisely known concentrations of various radionuclides, are necessary adjuncts to any analytical quality control program. In general, we prefer the use of “natural matrix standards,” samples into which the radionuclides have become incorporated under natural conditions, and over as long a time span as possible. Under some circumstances, however, real advantages are offered by “spiked sample standards” samples to which the isotope of interest has been added in a precisely known amount, at the time of preparing the standard. It is our purpose to discuss the advantages and disadvantages of spiked standards and to contrast them with those of natural matrix standards, as well as to discuss the preparation of the former class of standards and the evidence supporting our recommendation of caution in their use. In general, spiked standards offer advantages of low cost of preparation, of advance assurance that the amount and chemical form of the radioisotopes added are known, and of the possibility of preparation of unnatural matrices, or of nuclides that are to be expected but not yet to be found in nature. The most salient disadvantages of spiked standards derive from the usual uncertainty concerning the concentration of any radionuclides in the matrix before spiking and from the difficulty of insuring that there will be no difference in analytical behavior between the spike and the same isotope that has become incorporated in the matrix under natural conditions. Consideration of these advantages and disadvantages leads to identification of a list of special problems for which spiked standards may be advantageous and of a list of precautions indicated in the interpretation of the resulting data. The argument against the general applicability of spiked standards appear overwhelming.

Development of some natural matrix standards — Progress report

Abstract Substantial progress has been made in the production of environmental level, natural matrix, radioactivity standards of soil of low organic and low carbonate content, and of human lung and human liver. This is in response to the deliberations of the 1977 ICRM meeting at which the need for such standards was voiced and the criteria suggested. The soil samples have been reduced to optimum particle size and are ready for blending and standardization. A ten year supply of this standard should be ready in a year or less. Reducing the dried lung and liver to less than 74 μm has proven formidable because of the natural fat and oil content. Using cyrogenic milling techniques more than three quarters of the total mass of each has been reduced to the desired particle size; the balance will either be reduced or removed and we can then proceed to the final standardization.

Time pattern of off-site plutonium deposition from rocky flats plant by lake sediment analyses

A sediment core from a lake downwind of the Rocky Flats Plant, where nuclear weapons components are produced, was used to reconstruct a time pattern of off-site plutonium deposition. Core sections were dated by analyses of 137Cs, 239,240Pu, 238Pu, and 241Am fallout from nuclear testing and 238Pu fallout from a satellite failure. A peak in transuranic concentrations occurred in late 1969 which was attributable to the Plant. This was confirmed by mass isotopic analysis of plutonium isotopes in selected core segments where the global fallout and Plant contributions could be differentiated. The 18 nCi 239,240Pu per m2 from the Plant that had accumulated in the sediment is reasonable when compared to soil analyses.

Threat to the New York City water supply--plutonium.

The mayor of the City of New York received an anonymous letter on April 1st 1985 threatening to contaminate the water supply with plutonium unless all criminal charges against Mr Bernhard Goetz, the suspect in a dramatic subway shooting incident, were dismissed by April 11th 1985. Local and Federal authorities were called upon to evaluate the credibility of the threat and to institute a round the clock monitoring program by New York City personnel. The Environmental Measurements Laboratory, EML, was requested by the City to analyse a composite, large volume (approximately 175 litres) drinking water sample collected by City personnel on April 16th 1985. The concentration measured was 21 fCi/l which was a factor of 100 greater than previously observed results in our data base, and the mass isotopic content of the plutonium was very unusual. Additional samples were collected one to three months later at various distribution points in the water supply system. The plutonium concentrations were much lower and comparable to EMLs earlier data. Mass isotopic analysis of these samples provided more reasonable compositions but with high uncertainties due to very low plutonium concentration. Recent measurements of large volume samples, approximately 1000 litres, collected in the Fall of 1985 from the New York City and New Jersey water supplies showed identical plutonium concentrations of 0.05 fCi/l. Mass isotopic analyses indicated similar 240Pu/239Pu ratios which were slightly lower than global fallout estimates. Due to our inability to confirm the elevated plutonium concentration value for the composite sample of April 16th 1985, it is impossible to conclude whether the threat to contaminate the New York City water supply was actually carried out or whether the sample was contaminated prior to receipt at EML.

Time history of trace elements in sediments from Standley Lake, Colorado

Abstract Eighteen trace elements were analyzed in sections from a 50 cm long sediment core from Standley Lake, Colorado. The core was dated by the use of bomb-produced 137Cs. Ten of the elements measured (Ag, Cd, Cu, Ga, Hg, Pb, Se, Sn, Tl, and Zn) appear to be enriched in this sediment; seven (Al, As, Be, Co, Cr, Ni, and V) are probably of local geological origin; and Te was not detected. Several of the constituents increase with depth in the sediment, and the concentrations of some compare to levels in lake sediments near highly industrialized centers. Based upon comparisons with other work, fluxes, enrichment factors, benzo(a)pyrene concentrations, and other evidence we conclude that the primary source of the “excess” elemental concentrations is local stream pollution.

Natural matrix radioactivity standards and reference materials

Abstract Although the precise definitions of Natural Matrix Standard (NMS) and Natural Matrix Reference Material (NMRM) remain somewhat unclear, few doubt their extreme usefulness in virtually all programs involving measurements of radioactivity. Rigorous quality assurance/quality control is difficult, if not impossible, particularly in studies requiring radiochemical/radiometric analyses of environmental matrices, when lacking good NMSs and NMRMs. A fairly comprehensive range of these materials is now available internationally, at a reasonable cost. Progress on the National Bureau of Standards NMS program as well as EMLs Quality Assessment Program are discussed. In addition 99 Tc in vegetation is presented as a specific example of the methodology of preparing a NMRM.

Nuclear Power in Space

MF01/PCO2 Plus Postage. *Aerospace Technology; College Science; Higher Education; *Nuclear Energy; *Nuclear Technology; Radioisotopes; Safety; *Satellites (Aerospace); Science Education; *Space Exploration; Space Sciences; *Technological Advancement; Technology Transfer Research has shown that nuclear radioisotope power generators can supply compact, reliable, and efficient sources of energy for a broad range of space missions. These missions range from televising views of planetary surfaces to communicating scientific data to Earth. This publication presents many applications of the advancing technology and commemorates three important milestones in space technology research: (1) the emplacement of the Apollo Lunar Surface Experiments Package on the Moon in November 1969; (2) the first demonstration of nuclear power for space in January 1959; and (3) The Atomic Energy Act of 1954: as amended, that encouraged applications for nuclear energy in a broad range of scientific endeavors, including exploration of space. Spacecraft propulsion had contributions originating from a number of countries. The log of space flights began in November 1957 with the first artificial satellite, Sputnik-1. Presently the total number of satellites has grown to more than 1,693 and a primary vehicle for launching a variety of spacecraft and satellites for research and communications purposes is being provided by the United States Space Shuttle Program. Topics of information include: space power systems and types; key events; space exploration milestones; future planetary missions and generating systems; isotope power systems; and aerospace safety. (RT) 3000000000000000000000000000000000000000:3000080000000000000000000800EXX X Reproductic,ns supplied by EDRS are the best that can be made * * from the original document. * 30000000000000000000000000000000000000(30000600000000000000000000000000a