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Samantha Wolf, Mark Emerson, Derek Laskowsky. Microbial Activity in Arsenic Contaminated Soil. Hypothesis. Will soil previously contaminated with CCA contain microbes that show more resilience to prolonged exposure to CCA wood than microbes in an uncontaminated soil? . Introduction. - PowerPoint PPT Presentation
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Microbial Activity in Arsenic Contaminated Soil
Samantha Wolf, Mark Emerson, Derek Laskowsky
Hypothesis
Will soil previously contaminated with CCA contain microbes that show more resilience to prolonged exposure to CCA wood than microbes in an uncontaminated soil?
Introduction
The purpose of CCA is to prevent rot and damage to lumber from termites, effectively acting as a pesticide, in addition to strengthening the lumber.
During the 1940’s the lumber industry began its large-scale treatment of lumber with chromated copper arsenate (CCA) for preservation.
Introduction Cont.
The complications brought on by the CCA treated lumber is the leaching of chromated copper arsenate into the surrounding soil.
The focus of this study is to determine if CCA exposed microbes are resilient to the CCA, compared to non-CCA exposed microbes.
Methods: Soil sampling and analysis Soil samples from 3”, 6”, and 9”
from CCA contaminated site.
Soil sample and analysis
Metal Concentrations
Sample at 3”: Arsenic at 63.5
ppm cadmium at 2.2
ppm chromium at 31
ppm copper at 44 ppm
Average concentrations:
Arsenic 6.5 ppm cadmium at 0.1 -
1.0 ppm chromium at 70
ppm copper at 20 ppm
Microbial Enrichment
Brain-heart nutrient broth in shaker incubator for 1 week.
Control, CCA Soil, Control soil with 2.2g CCA wood, CCA Soil with 2.2g CCA wood.
Colony Forming Units
Plated on agar, incubated for 24 hrs.
Counted and extrapolated to 10^4
CFU Count
0
50000
100000
150000
200000
250000
300000
350000
400000
Colony count per sample
Results
All results are per .5ml
Bact
eria
Col
onie
s
Conclusion
The CFU count was highest in the CCA soil sample inoculated with the CCA wood chip. The microbes in the soil must be conditioned to presence of arsenic.
Arsenic loving microbes.