1. Eisenia fetida as a bioindicator of arsenic rich soils in Hawaii
Russell Auwae
Sponsors: Dr. Theodore Radovich and Dr. Nguyen HueSponsors: Dr. Theodore Radovich and Dr. Nguyen Hue
University of Hawaii at Manoa, Department of Tropical Plant
and Soil Sciences (TPSS)
IS 489: Environmental Practicum
12/08/10

2. Background: Arsenic Accumulation
High concentrations of arsenic on abandoned sugarcane lands
– Arsenic-based herbicides used for weed control during the
1920s to 1950s
– Converted to residential and commercial areas
Adverse Health Effects:Adverse Health Effects:
– Skin lesions and hardenings
– Cancers
– Neurological disorders

3. Study Site: Kea’au, HI
-Proposed hotel site
-New housing
-New schools

4. Questions
Bioaccessibility and Chemical Behavior:
– What is the bioaccessible amount of arsenic in the soils?
• Bioaccessible- amount available for absorption by the body
– Does arsenic affect earthworm (Eisenia fetida)
performance (mortality/survival/growth)?performance (mortality/survival/growth)?

5. Hypothesis
• There will be higher bioaccessible arsenic in Kea’au soil than
Waimanalo soil.
• Earthworm performance will decrease with increasing
amounts of arsenic.
Objectives
Measure the:
• Performance (mortality/survival/growth) rate
• Bioaccessible arsenic in the soils

6. Setup of Treatments
• 600g of soil per pot:
– Treatment 1: 100% Waimanalo
– Treatment 2: 75% Waimanalo + 25% Kea’au
– Treatment 3: 50/50 Waimanalo + Kea’au
– Treatment 4: 75% Kea’au + 25% Waimanalo– Treatment 4: 75% Kea’au + 25% Waimanalo
– Treatment 5: 100% Kea’au
• Three replicates per treatment type
• Eight earthworms per pot

7. Pictures

8. Lab Analysis
• Weighed with a balance
• Measured bioaccessible arsenic with an inductively coupled
plasma spectrometer (ICP)

9. Results
NumberofTrials Waimanalo(g) Kea'au(g) EstimatedTotalAs(mg/kg) BioaccessibleAs(mg/kg) InitialEW(g) 2wksEW(g) 4wksEW(g) 6wksEW(g)
1 600 0 20 1.45 2.1 2.2 3.4 3.4
2 450 150 90 3.04 2.2 3.0 4.4 4.2
3 300 300 160 5.87 2.3 4.0 5.2 5.1
4 150 450 230 6.33 2.0 4.5 5.4 5.4
5 0 600 300 6.86 2.1 4.4 5.4 6.0
6 600 0 20 1.13 1.6 2.5 3.9 4.46 600 0 20 1.13 1.6 2.5 3.9 4.4
7 450 150 90 2.34 1.9 4.0 5.8 6.0
8 300 300 160 4.70 2.4 5.4 6.1 5.8
9 150 450 230 4.95 1.7 3.5 5.0 4.9
10 0 600 300 8.17 1.7 3.6 4.6 4.2
11 600 0 20 1.22 1.6 4.4 5.5 5.1
12 450 150 90 3.53 1.4 3.7 4.5 4.4
13 300 300 160 5.64 1.9 4.6 5.6 4.9
14 150 450 230 6.76 1.7 4.4 5.4 5.0
15 0 600 300 9.44 1.8 4.9 6.1 6.1

10. Results
RelativeWormWeight(%)RelativeWormWeight(%)
Bioaccessible As (mg/kg)

11. Caveat
• Bioaccessible arsenic exceeds daily exposure of 0.004-0.007
mg/kg per day
• Serious threat to:
– Residents
– Workers
– Schools– Schools
– Civic centers
• Solutions:
– Wear protective gear (gloves, long-sleeve clothing, safety
glasses, or dust masks)
– Plant grass over exposed soil
– Keep children from playing in contaminated soil
– Wash hands and face after working or playing
– Wash fruits and vegetables

12. Conclusion
• Bioaccessible arsenic ranged from 1.13-9.44 mg/kg
• Growth of Eisenia fetida peaked at about 2 mg/kg of
bioaccessible arsenic
• Evidence of a hormetic effect
– Favorable biological responses to low doses of a toxin or– Favorable biological responses to low doses of a toxin or
stressor

13. Further Research
• Do endogeic and/or anecic earthworms respond differently to
arsenic contaminated soils?
• Does different arsenic concentrations affect the earthworm
reproduction?
• How much arsenic accumulated in the earthworms?• How much arsenic accumulated in the earthworms?
• Economical ways of soil remediation
– Excavation
– Phytoremediation

14. Acknowledgements
• Dr. Theodore Radovich
• Dr. Nguyen Hue
• Dr. John Cusick