Thomas L. Gibson

Nitro derivatives of polynuclear aromatic hydrocarbons in airborne and source particulate matter

Abstract The concentrations of 1-nitropyrene and 6-nitrobenzo(a)pyrene were measured in a variety of airborne and source particulate samples and appeared to be correlated with the mutagenicity ( Salmonella TA-98, direct-acting). Data available are insufficient to allow source allocation for these compounds in the atmosphere.

Evidence for the transformation of polycyclic organic matter in the atmosphere

Abstract The ratios of 1-nitropyrene and hydroxynitropyrenes to inert marker species (fine particulate lead, selenium, and elemental carbon) were considerably higher at a remote site on Bermuda than in Delaware. The results suggested that these nitroaromatic POM are formed in atmospheric reactions. The ratio of benzo( a )pyrene to marker species was not significantly different at the two sites. This result did not reflect the expected loss of BaP in atmospheric photochemical reactions.

Sources of Nitroaromatic Mutagens in Atmospheric Polycyclic Organic Matter

The distribution of mutagenic activity and nitroaromatic components of polycyclic organic matter (POM) in ambient air at industrial, urban, suburban, rural, and remote sites was studied using organic extracts from high volume aerosol samples. Direct-acting mutagens including 1-nitropyrene (1-NP), dinitropyrenes (DNP), and hydroxynitropyrenes (HNP) were measured by high performance liquid chromatography while the mutagenicity was determined in the Salmonella bioassay with strain TA-98. Benzo(a)pyrene (BaP), one of the possible precursors of nitroaromatic compounds in POM, was also measured. In comparing samples from a range of sites, TSP and the concentration of BaP per mass of particulate matter decreased, as expected, at greater distances from urban and industrial combustion sources. However, the concentrations of polar nitroaromatic POM compounds per mass of particles were higher at a remote site than in nonindustrial urban and suburban areas. The mutagenicity in particulate matter extracts from the rem...

Contamination of soil and groundwater by automatic transmission fluid: site description and problem assessment.

Soil and groundwater beneath a region of a manufacturing plant are contaminated with automatic transmission fluid (ATF). The extent of contamination was assessed by maximizing the use of real-time data from soil-core sampling and monitoring wells. The number, location, and depth of cores and of monitoring wells were determined during the investigation based on: (1) inspection and analysis of soil-core samples immediately after each core was taken; (2) physical and chemical measurements of core samples at the end of each day; (3) measurements in monitoring wells at several stages during the investigation. This approach differs significantly from the conventional approach of randomly placing wells through the hydrogeologic system. Soil cores were taken and monitoring wells installed at 53 locations. The perched aquifer extends to about 13 ft. and is comprised mainly of sandy materials, which have spatial heterogeneity in size distribution and hydraulic properties. About 208 000 ± 33 000 gal. of ATF has spread over an area of about 64 000 ft.2. The region of ATF contamination is comprised of three distinct and contiguous layers. The center layer is about 2.6ft. deep at its thickest point and extends to about 250ft. at its widest point. The soil in this zone is about 85% saturated with 133 000 ± 21 000 gal. of ATF, which has depressed the water table into the aquifer. The top layer is about 14in. thick and econtains about 50640 gal. of ATF held by capillary forces. The amount of ATF in this zone decreases with height above the center layer from about 85% saturation to residual saturation (20%). The amount of ATF in the deepest layer is near the residual saturation. This layer is 1.0 ± 0.5 ft. thick and has 24 500 ± 12 250 gal. ATF. This investigative approach did not spread the ATF to clean regions of the aquifer as could occur with conventional approaches, and it provided the data needed to assess the problem and to design a cleanup plan. A new approach is being used to recover the free ATF at the site.

Solar photovoltaic charging of lithium-ion batteries

Solar PV battery charging was tested by using crystalline and amorphous silicon PV modules to recharge lithium-ion battery strings. The iron phosphate type batteries were charged to their maximum capacity with optimum efficiency while avoiding thermal hazards associated with overcharging due to the self-regulating design of the solar charging system.