RESUMEN
This paper describes the results of a preliminary project conducted by a team of DePaul University undergraduate students and staff from the Gary Comer Youth Center located on Chicago's South Side. The team assessed soil quality on 116 samples collected among four abandoned residential lots adjacent to the Comer Center. Soil quality data will be used in a follow-up study to determine the suitability of each lot for green infrastructure implementation. Green infrastructure may be a useful approach for providing ecosystem services and mitigating food deserts in inner-city communities. Soil quality on all lots was poor. All soils had pH >8.0, low biological activity, and low N mineralization potential. The soils were rich in available P and had mean total Pb concentrations above the USEPA threshold (400 mg kg) for children's playlots. Mean bioavailable Pb on the largest of the four lots was 12% of total Pb, indicating that most of the total Pb is not bioavailable. This result is encouraging because high bioavailable Pb concentrations are linked with negative health effects, particularly in children. All lots had NO-N concentrations below those considered to be appropriate for plant growth. On the other hand, no significant differences in mean concentrations of the other analytes were found. The poor soil quality in the four lots presents an opportunity to use green infrastructure to enhance ecosystem services, improve community and environmental health, and provide more equitable access to green space.
Asunto(s)
Salud Ambiental , Contaminantes del Suelo/análisis , Niño , Conservación de los Recursos Naturales , Monitoreo del Ambiente , Estudios de Seguimiento , Humanos , SueloRESUMEN
Escherichia coli serotype O157 strains, which may be found in foods, often produce enterohemorrhagic toxins. The research goal was to facilitate rapid, sensitive detection in foods of E. coli serotype O157 by flow cytometry. Sample preparation methods were developed for potential use in 15 foods. Combined with multi-dimensional gating, these methods decreased time-to-results (TTR) for determination of low-level contamination. They mitigated the effects of interfering food components, concentrated cells for analysis without growth or, when necessary, used short-term incubation. The results showed qualitative analysis that was equivalent to culture plating in accuracy and superior in sensitivity and speed. Preparation time was 10-30 min per sample and detection took 3-4 min. Culture growth, if required, took an additional 4-6 h. A protocol for raw spinach analysis, using 4 h culture incubation, was 94% correct with one false negative for a low level inoculation. Its projected limit-of-detection (LOD) was 1 viable cell per 25 g of spinach, based on an average of 28 counts detected after growth and an estimated counts-to-threshold (C/T) ratio of 1.3. The results suggested potential uses for regulatory screening and food industry process control.