Long-term behavior of passively aerated compost methanotrophic biofilter columns.

The methane oxidation potential of several types of compost methanotrophic biofilter columns were compared in the laboratory over a period of 220 days. The results indicate an increase in methanotrophic activity over a period of about 100 days, up to a maximum of 400 g m(-2) day(-1), and a gradual decline to about 100 g m(-2) day(-1) within the next 120 days. High methane oxidation rates appear to be restricted to a small area of the column, 10-15 cm thick. Based on the laboratory investigations carried out to determine the cause for the decline in methane oxidation rate, it was concluded that the formation of exopolymeric substances (EPS), at the zones of maximum methane oxidation, was responsible for this decline. In monitoring methane oxidation in a column for up to 600 days, it was observed that mixing of the medium after formation of EPS enabled the column to temporarily recover high performance. The results suggest that stable, homogenous compost, with a low C/N and low ammonium content, mixed on a regular basis, could achieve and maintain high methane oxidation efficiencies.

Methane oxidation in three Alberta soils: influence of soil parameters and methane flux rates.

Current concern over the potentially negative impacts of climate change has brought attention to anthropogenic sources of methane, a primary greenhouse gas. Two such emission sources are methane leakage at heavy oil wells and sanitary landfills. At both of these sources, substantial quantities of methane could potentially be oxidised by methanotrophic microbes living in soils. Optimisation of this phenomenon may serve as an inexpensive technique for reducing methane emissions. Soil column and batch incubation experiments were performed on a landfill loam, an agricultural loam and a sedge peat to gain a better quantitative understanding of the biological and physical processes limiting CH4 oxidation in soils that undergo the freeze-thaw cycles associated with northern climates. Moisture content emerged as a critical variable that can limit a soil's CH4 oxidation potential. For example, the oxidation rate of the agricultural soil was seen to increase by an order of magnitude after increasing its moisture content from 6% to 10% of its dry weight.

A simple, reliable method for the determination of chlorinated volatile organics in human breath and air using glass sampling tubes.

A method for determining chloroform, 1,1,1-trichloroethane, carbon tetrachloride, and trichloroethene in breath samples was developed. It consisted of collecting samples in 40-ml. glass-silanized tubes that were 16-in. long and had a 0.64-in. diameter. The ends tapered, resulting in a tube with a 1/4-in. diameter that was 1 3/4-in. long; each end had a shutoff valve attached. One end had a strip of rubber tube attached to the shutoff valve for collecting the breath sample, and the other end contained a 1/4-in. Swagelok nut with a rubber septum for withdrawing the sample. Samples were withdrawn using a pressure-lock, gastight syringe, and they were injected onto a gas chromatograph fitted with an electron-capture detector. The analytes were stable for at least 22 days in these tubes. The method detection limit was determined to be 0.03, 0.08, 0.04, and 0.04 pg/ml. for chloroform, 1,1,1-trichloroethane, carbon tetrachloride, and trichloroethene, respectively. Precision, based on 13 injections, was determined to be 13% for 0.09 pg chloroform, 13% for 0.21 pg 1,1,1-trichloroethane, 8% for 0.16 pg carbon tetrachloride, and 14% for 0.1 pg trichloroethene. In all, the proposed method is a sensitive and reliable one for determining volatile organic compounds in breath and a method that can also be applied to air sampling.

A simplified method for the determination of volatiles in eggs using headspace analysis with a photoionzation detector.

Headspace sampling of whole eggs at 50 degrees C was used to determine benzene, toluene, trichloroethene, tetrachloroethene, chlorobenzene, ethylbenzene, ortho-, meta-, and para-xylenes as sources of contamination. A 30-m, 0.53-mm ID fused silica capillary column coated with 1.0 micron (5%) methyl silicone attached to a photoionization detector was used to separate and detect the volatiles. The sensitivity of the method was 0.002 microgram/mL with an average precision for all nine compounds of 16.5 +/- 3.1% (n = 10) for a 0.01 microgram/ml standard.

Simplified method for determining polychlorinated biphenyls, phthalates, and hexachlorocyclohexanes in air.

A simplified method for determining polychlorinated biphenyls (PCBs), phthalates, and benzene hexachlorides (BHCs) in air has been developed. Florisil is used as the adsorbent, and compounds are eluted by liquid chromatography with 10% 2-propanol in hexane. PCBs are separated from phthalates plus BHCs on a cyanopropyl column with a gradient containing 10% 2-propanol in hexane and 100% hexane as the mobile phase. Two fractions are collected: one contains PCBs and the other contains phthalates plus BHCs, which are then determined by gas chromatography using a 63Ni electron-capture detector and a DB-5-bonded, fused-silica capillary column.

Subchronic exposure of mice to Love Canal soil contaminants.

The health hazard potential of soil collected from the surface of the Love Canal chemical dump site in Niagara Falls, New York, was assessed in 90-day exposure studies. Female CD-1 mice were exposed to two concentrations of the volatile components of 1 kg of soil with and without direct soil contact. Control mice were identically housed but without soil. The soil was replaced weekly and 87 compounds were detected in the air in the cages above fresh and 7-day-old soil as analyzed by gas chromatography/mass spectrometry. The concentration of many of these compounds decreased during the 7-day exposure cycle. Histopathologic, hematologic, and serum enzyme studies followed necropsy of all mice. There was no mortality of mice exposed for up to 90 days under any condition. Thymus and spleen weights relative to body weight were increased after 4 weeks of exposure by inhalation but not after 8 or 12 weeks of exposure. alpha-, beta-, and delta- Benzenehexachlorides , pentachlorobenzene, and hexachlorobenzene were detected in liver tissue from these animals. Mice exposed to 5- to 10-fold elevated concentration of volatiles had increased body and relative kidney weights. There was no chemically induced lesion in any animal exposed only to the volatile soil contaminants. Mice exposed by direct contact with the soil without elevated volatile exposure had increased body (10%) and relative liver weights (169%). Centrolobular hepatocyte hypertrophy, which involved 40 to 70% of the lobules, was observed in all mice in this group.(ABSTRACT TRUNCATED AT 250 WORDS)

Chlorinated compounds and phenols in tissue, fat, and blood from rats fed industrial waste site soil extract: methods and analysis.

A method was developed to analyze rat tissue, fat, and blood for some of the chlorinated compounds found in an extract of soil from an industrial waste site. Extraction with hexane and then with ethyl ether-hexane (1 + 1) was followed by concentration over steam, and gas chromatographic analysis with an electron capture detector. Volatile compounds were analyzed in a glass column coated with 6% SP-2100 plus 4% OV-11 on Chromosorb W. Semivolatile compounds, chlorinated compounds, and pesticides were analyzed in a 70 m glass capillary column coated with 5% OV-101. Phenols were analyzed in a glass column packed with 1% SP-1240 DA on Supelcoport. However, the most efficient means of separation was to use the same glass column for volatile compounds, a DB-5 fused silica capillary column for semivolatile compounds, pesticides, and phenols, and the same 1% SP-1240 DA glass column for separation of beta-BHC and pentachlorophenol. Recoveries ranged from 86.3 +/- 9.1% (mean +/- standard deviation) to 105 +/- 10.4%. Sensitivities for semivolatile chlorinated compounds, pesticides, and phenols were about 4 ng/g for fat, 1 ng/g for tissue, and 0.2 ng/mL for blood. Sensitivities for volatile compounds were about 4-fold higher (16, 4, and 0.8, respectively). Sensitivities for dichlorobenzenes and dichlorotoluenes were 8 ng/g for fat, 2 ng/g for tissue, and 0.4 ng/mL for blood.

Gas-liquid chromatographic determination of azinphos ethyl in human plasma and in mouse plasma, tissue, and fat.

A new method for the determination of azinphos ethyl (O,O-diethyl-S-(4-oxo-1,2,3-benzotriazin-3(4H)-ylmethyl) phosphorodithioate) in human plasma and in mouse plasma, tissue, and fat has been developed. The method is based on extraction with benzene or hexane and cleanup of fat and tissue samples by a minicolumn containing Florisil and sodium sulfate. Azinphos ethyl is eluted from the column with 10% acetonitrile in benzene and is concentrated to an appropriate volume for gas-liquid chromatographic analysis, using a 63Ni electron capture detector and a glass column containing 3% OV-1 on Gas-Chrom Q. The method is sensitive to 0.005 ppm in human plasma, 0.01 ppm in mouse plasma, 0.08 ppm in mouse liver, 0.05 ppm in mouse brain, and 0.10 ppm in mouse fat. The limit of detection is 2 pg; mean recoveries ranged from 96 to 98%.