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Joseph S. Duval

Publications and source records attributed to Joseph S. Duval.

48 records · Page 3Linked to original sources
USGS1988

Map showing radon potential of rocks and soils in Fairfax County, Virginia

Since 1984, indoor radon has gained national attention as a significant health hazard in the United States. Radon is a colorless, odorless, radioactive gas derived from uranium by radioactive decay. The U.S. Environmental Protection Agency (EPA) now projects that 5,000 to 20,000 lung-cancer deaths per year may be attributed to the long-term exposure to indoor radon and its radioactive decay products. Indoor radon has been previously recognized as a health hazard associated with uranium-bearing mill tailings or building materials, but it was not until December 1984 that some natural soils and rocks were found to be sources of indoor radon at levels comparable to those in uranium mines. It is now suspected that elevated indoor radon levels are far more widespread than initially though. The EPA considers 4 picoCuries of radon per liter of air (pCi/L) as the level (in a year-round measurement) at which actions ought to be taken to lower the concentration of indoor radon. All soils and rocks contain measurable amounts of uranium, which generate measurable amounts of radon. Certain soils and rocks, however, have a greater potential to cause indoor radon problems than others because (1) they have a higher uranium content and thus can generate higher levels of radon in soil gas (gas that occupies the pores of the soil), and (2) the permeability of the sol or rack is sufficiently high that radon-bearing soil gas can flow freely and move indoors through the foundation of the structure. This study was designed to demonstrate the correlation between the geologic environment and indoor radon levels and to demonstrate a method of assessment that could be used by other informed workers in areas of their interest. A parallel study by Gundersen and others (1988) of the radon potential of rocks and soils in Montgomery County, Md., used somewhat different methods of assessment because the data available for and assessment of Montgomery County differed.

Virginia↗
USGS1985

PROCEDURES FOR ACCURATE PRODUCTION OF COLOR IMAGES FROM SATELLITE OR AIRCRAFT MULTISPECTRAL DIGITAL DATA.

Because the display and interpretation of satellite and aircraft remote-sensing data make extensive use of color film products, accurate reproduction of the color images is important. To achieve accurate color reproduction, the exposure and chemical processing of the film must be monitored and controlled. By using a combination of sensitometry, densitometry, and transfer functions that control film response curves, all of the different steps in the making of film images can be monitored and controlled. Because a sensitometer produces a calibrated exposure, the resulting step wedge can be used to monitor the chemical processing of the film. Step wedges put on film by image recording machines provide a means of monitoring the film exposure and color balance of the machines.

Journal of Imaging Technology↗
USGS1981

Interpretation of an aerial radiometric survey of the San Gorgonio Wilderness Area and vicinity, San Bernardino County, California

The aerial radiometric data for the San Gorgonio Wilderness Area show slight correlation with mapped geology and contain no information of economic significance. Precambrian and modified Precambrian crystalline rocks have more eTh compared to Mesozoic plutonic rocks and one rock unit mapped as a pluton has slightly more K. These rocks have essentially uniform ratios of eU/eTh and eU/K despite their different origins. The ratios and also show that part of the granodiorite of Manzanita Springs could be somewhat deficient in eTh and K. It is concluded that the mapped radioelement distributions are within reasonable limits for the rock types involved, and there is no immediate evidence on any anomalous concentrations of radioactive minerals within the Wilderness Area.

California↗
USGS1981

Map showing mineral resource potential of the Sierra Ancha Wilderness and Salome Study Area, Gila County, Arizona

The Wilderness Act (Public Law 88-577, Sept. 3, 1964) and certain related Acts require the Geological Survey and the Bureau of Mines to survey certain areas on Federal lands to determine their mineral-resource potential. Results must be made available to the public and be submitted to the Administration and the Congress. These maps and reports present the results of a geologic and mineral survey of the Sierra Ancha Wilderness and Salome Study Area, Gila County, Arizona.

Arizona↗
USGS1981

Aerial radiometric and magnetic surveys, Snowy Range Wilderness Study Area and contiguous area, southeastern Wyoming

The Wilderness Act (Public Law 88-577, Sept. 3, 1964) and related acts require the U.S. Geological Survey and the U.S. Bureau of Mines to survey certain areas on Federal lands to determine their mineral resource potential. Results must be made available to the public and be submitted to the Administration and the Congress. This report presents the results of a geophysical survey of the Snowy Range Wilderness Study Area and Contiguous Area, Wyoming.

Wyoming↗
USGS1980

Interpretation of an aerial radiometric and magnetic survey of the Salmo-Priest study area (RARE E6-981 A1-981), Pend Oreille County, Washington and Boundary County, Idaho

An aerial radiometric and magnetic survey of the Salmo-Priest study area (RARE E6-981) (index map) was made by the U.S. Geological Survey during October, 1978. Geophysical data from the survey will be used in the assessment of the mineral-resource potential of the study area. The Salmo-Priest area is located in northeastern Washington and northern Idaho and the north edge is the United States-Canadian boundary. This report presents the data obtained by the survey and an interpretation of the data.

Idaho, Washington↗
USGS1977

Calibration constants for the Geodata International, Inc., and Texas Instruments, Inc.: High sensitivity systems used for the ERDA aerial gamma-ray surveys

The radiometric data from the ERDA aerial gamma-ray surveys have been presented in the form of count rates proportional to the apparent, average surface concentrations of potassium (K), equivalent uranium (eU), and equivalent thorium (eTh). Data from a U.S. Geological Survey calibrated, truck-mounted gamma-ray spectrometer have been used to estimate calibration constants that can be used to convert the count rate data to absolute concentration units--percent K, parts per million (ppm) eU, and ppm eTh. Calibration constants for the gamma-ray systems of Geodata International, Inc. and of Texas Instruments, Inc. as they were configured prior to September 1976 are presented.

Open-File Report↗
USGS1977

Interpretation of an aeromagnetic anomaly in McMullen and Live Oak counties, Texas

An anomaly about 300 gammas in amplitude has been observed in data from an aerial magnetic survey flown over parts of Duval, Live Oak, McMullen, and Webb Counties, Tex. A two-and-one-half-dimensional model was used to iterpret the data, and the anomaly is apparently caused by a large mafic body centered near 28?10'N and 98?22'W, with an area of about 1800 km2 at a depth of 10 km.

Open-File Report↗