Volatile organic compounds (VOCs) in solid waste landfill cover soil: Chemical and isotopic composition vs. degradation processes.

Landfills for solid waste disposal release to the atmosphere a large variety of volatile organic compounds (VOCs). Bacterial activity in landfill cover soils can play an important role in mitigating VOC emission. In order to evaluate the effects of degradation processes and characterize VOCs composition in landfill cover soil, gases from 60 sites and along 7 vertical profiles within the cover soil were collected for chemical and isotopic analysis at two undifferentiated urban solid waste disposal sites in Spain: (i) Pinto (Madrid) and (ii) Zurita (Fuerteventura, Canary Islands). The CO2/CH4 ratios and δ13C-CO2 and δ13C-CH4 values were controlled by either oxidation or reduction processes of landfill gas (LFG). VOCs were dominated by aromatics, alkanes and O-substituted compounds, with minor cyclics, terpenes, halogenated and S-substituted compounds. Degradation processes, depending on both (i) waste age and (ii) velocity of the uprising biogas through the soil cover, caused (i) an increase of degradation products (e.g., CO2, O-substituted compounds) and (ii) a decrease of degradable components (e.g., CH4, alkanes, alkylated aromatics, cyclic and S-substituted compounds). Terpenes, halogenated compounds, phenol and furans were unaffected by degradation processes and only depended on waste composition. These results highlight the fundamental role played by microbial activity in mitigating atmospheric emissions of VOCs from landfills. Nevertheless, the recalcitrant behaviour shown by compounds hazardous for health and environment remarks the importance of a correct landfill management that has to be carried out for years after the waste disposal activity is completed, since LFG emissions can persist for long time.

Maxillary sinus anatomic and pathologic CT findings in edentulous patients scheduled for sinus augmentation.

OBJECTIVES: An aberrant sinus anatomy or pathology can influence the sinus lift technique if it is encountered during surgical exposure. The purpose of the present study was to determine the prevalence of sinus disease and variations of normal anatomy among edentulous patients prior to sinus augmentation. MATERIAL AND METHODS: 120 patients attending a private surgical practice (53 women and 67 men, with a mean age of 62.02 years, ranging between 34 and 81 years old) for whom treatment was planned for sinus augmentation were evaluated--medical history, radiographic and clinical examinations. Computerized tomograms (CT) and 3D reconstructions from 240 sinuses were analyzed using Dental CT. RESULTS: Abnormalities were diagnosed in 74.2% of cases. Mucosal thickening was the most prevalent abnormality (68.3%), followed by retention cysts (15.8%) and opacification (9.2%). The diagnosed conditions included mucosal thickening, chronic sinusitis, sinus cysts and polyps. The prevalence of one or more septa per sinus was found to be 30%. Males present pathology more often than females (p=.028). No statistical correlation could be found between age and pathology (p>0.05) No significant differences in age or gender between patients with and without sinus septum were found (p>0.05). CONCLUSIONS: The results reinforce the importance of thorough history taking and clinical and radiographic assessment prior to performing sinus augmentation, to prevent the probability of complications.

High-performance liquid chromatographic analysis of carbofuran residues in tomatoes grown in hydroponics.

Tomato plants grown in hydroponics were irrigated three times on alternate days with nutrient solutions fortified with carbofuran at levels of 36, 111 and 222 mg 1-1, and carbofuran residues were analysed in tomato fruits. Residues were found to be below the maximum residue level set up by Codex Alimentarius Mundi (0.1 mg kg-1) 6, 11 and 18 days after the third irrigation with nutrient solutions fortified with carbofuran. Consequently, the withholding period of 60 days may be reduced to allow continuous harvest of tomatoes under the conditions used in this experiment.

Determination of carbofuran by GLC/NPD and HPLC in tomato fruits.

Two analytical methods, using GLC/NPD and HPLC to analyse carbofuran residues in tomatoes, are described. Both methods have shown a high recovery rate, up to 90%, and their detection limits are below the maximum residue limit set by Codex Alimentarius Mundi for carbofuran in tomatoes. Therefore, both methods may be of use in routine analysis of this pesticide in those fruits.