Simplified determination of polycyclic aromatic hydrocarbons.

Accurate quantitative analysis for selected polycyclic aromatic hydrocarbons present on urban dust can be obtained by using a simple procedure consisting of sonic-probe extraction with cyclohexane; clean-up with Florisil((R))-XAD-4((R)), and measurement by high-resolution gas chromatography with flame-ionization detection (HRGC/FID). The analysis can be further simplified by eliminating the clean-up step if HRGC/electron-impact mass-spectrometry (MS) is available. Both the FID and MS methods give results consistent with those obtained by standard procedures. The direct HRGC/MS procedure, combined with chemical ionization, can also be applied to the determination of polycyclic organic materials present in solvent-refined coal, shale oil and crude oil.

Degradation of aromatic compounds in ground-water, and methods of sample preservation.

The degradation of acenaphthylene, acenaphthene, 2-methylnaphthalene, 2-methylindene, 3-methylindene and indene in water solutions was studied. These compounds at the 25-150 mug/l. level were almost totally degraded at ambient temperature within three days. The microbial population responsible for the degradation occurs naturally in ground-water taken from an aquifer in Ames, Iowa, which is contaminated with coal-tar products. These unidentified micro-organisms adapt readily to other waters when used as an inoculant for the degradation of aromatic compounds. The preservation of water to prevent such degradation was also investigated. Filtration through a 0.45-mum filter was found the most effective procedure for preserving the hydrocarbons in these waters.

Pesticides in ground water beneath irrigated farmland in Nebraska, August 1978.

During the 1978 irrigation season, 14 ground water samples were collected in the Central Platte region of Nebraska, an area known to have high nitrate-nitrogen (NO3--N) levels, and analyzed for the presence of 13 pesticide residues. Atrazine levels ranged from 0.06 microgram/liter to 3.12 microgram/liter and were correlated to NO3--N concentrations with a coefficient of r = +0.55. Nitrate-nitrogen concentrations were measured as indicators of deep percolation from irrigated lands and ranged from 17.1 mg/liter to 34.3 mg/liter. Alachlor levels ranged from less than 0.01 microgram/liter to 0.71 microgram/liter. The amounts of 2,4-D were indeterminate because of experimental problems. Levels of the herbicides silvex and EPTC were below the limits of detectability. Levels of the organochlorine insecticides endrin, gamma-BHC (lindane), dieldrin, DDT and its primary metabolite DDE, heptachlor and its primary derivative heptachlor epoxide, and methoxychlor were all below the detectable limits of 0.005-0.010 microgram/liter.

Analysis of various Iowa waters for selected pesticides: atrazine, DDE, and dieldrin-1974.

Atrazine, DDE, and dieldrin were extracted and concentrated from various surface, subsurface, and finished waters using the macroreticular resin method. Organic components in the concentrates from these waters were separated by gas chromatography; the amounts of the three pesticides in the waters ranged from 0.5 to 42,000 parts per trillion by weight. Every major watershed in the State of Iowa revealed some degree of pesticide contamination and seasonal variations were consistent with agricultural runoff models. Atrazine concentrations were highest of the three pesticides, a symptom of its widespread use in the corn belt. DDE also appeared in substantial quantities, providing further evidence of the persistence of DDT and its metabolites. Water from several shallow wells and finished water from many water treatment plants were also contaminated. Current treatment processes do not effectively remove these pesticides.