A research project was undertaken to assess the relative effectiveness and durability of a wide variety of liner materials when exposed to hazardous wastes under conditions simulating various aspects of service in waste storage and disposal facilities. The materials studied included compacted soil, admixes, sprayed-on asphalt and 32 polymeric membranes. Four partially crystalline polymeric sheetings, though not compounded for use as liners, were included in the study because of their known chemical resistance and their use in applications requiring good chemical and ageing resistance.The lining materials were exposed in test cells to 10 hazardous wastes (two acidic, two alkaline, three oil, a blend of lead, a pesticide and a briny industrial waste) and three media of known composition—deionized water, 5% aqueous solution of salt and a saturated solution of low-concentration (0.1%) tributyl phosphate. The polymeric materials were also exposed to wastes or environmental conditions under a variety of conditions that included primary one-sided exposure, immersion testing, two types of outdoor exposure and a pouch test. Some of the exposures were as long as 2700 days. New methods for testing polymeric materials are presented. Results indicated that some of the liner materials performed satisfactorily in contact with certain wastes but, because waste combinations can be highly specific, compatibility testing is needed to select a liner for a given waste.
We examined three 1992 Airbome Visible Infrared Imaging Spectrometer (AVIRIS) images of Jasper Ridge Biological Preserve (JRBP) for spectral changes associated with community type and for phenological patterns over the growing season. The images were obtained on June 2, September 4, and October 6, 1992 and were calibrated to surface reflectance. Images were analyzed with spec& mixture analysis using library endmembers representing green foliage, non-photosynthetic vegetation, and soils characteristic of the site. The images were co-registered in a Geographic Information System (GIS), along with a digital elevation model @EM) of the Menlo Park 7.5 min. quandrangle obtained from US Geological Service and a field-based vegetation map provided by the JRBP. Vegetation endmember fractions were used to define vegetation communities and compared to the field-based vegetation map. Because there the tmain did not have steep north and south facing slopes, adding a DEM to the analysis did not increase accuracy of the classification. Vegetation fractions can be related to patterns expected for wetlands and grasslands, and for evergreen and deciduous shrub and tree communities. After vegetation boundaries were defined using the field-based map, we extracted the mean vegetation spectrum and standard deviation of the spectrum for each vegetation type. Changes in AVIRIS spectra over the season were compared among communities and these spectra were compared to field-based reflectance and biochemistry measurements of foliage that were representative of each community over the same seasonal period.
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