Title: The Potential of Azolla caroliniana to Remove Arsenic From Contaminated Wastewater
1The Potential of Azolla caroliniana to Remove
Arsenic From Contaminated Wastewater
- Prepared by
- Alex Duncan
- MS Student
- Dept. Environmental Science
2Agenda
- Background
- Discuss sources and problems with arsenic
contamination - Recent Research
- Introduce the topic and discuss relevant research
- Potential Scientific Breakthrough
- Discuss current gaps and explain how my project
will advance ecological science
3What is Arsenic
- Metalloid widely distributed in the earths crust
- There are four common arsenic forms
- Organic forms of monomethylarsenic acid (MMAA)
and dimethylarsenic acid (DMAA) - Inorganic forms of arsenite (As III) and arsenate
(As V). - The inorganic forms of arsenic are more toxic
than the organic ones
4Where Does It Come From ?
- Natural Sources
- Weathering of Bedrock
- the most common of which is arsenopyrite.
- Anthropogenic Byproducts
- Industry and Agriculture
5Beautiful, but Deadly
6Historical Uses
- Poison of Kings and the King of Poisons.
- Linked to the death of Napoleon Bonaparte, King
George the III of Britain, and impressionist
painters such as Van Gogh and Monet. - Used as a bronze alloy during the Bronze Age
- Mixed with chalk and vinegar and eaten by women
of the Victorian era to improve their complexion.
7Anthropogenic Sources
Burning Fossil Fuels
Wood Preservatives
Leaded gasoline
Fungicides
Electronics Manufacturing
Herbicides
Clarifying Glass
Insecticides
Many More
8Human Exposure
- Main route of human exposure to arsenic is by
ingestion of arsenic-contaminated food. - Wine and Tobacco sprayed with arsenic containing
pesticides - Seafood, certain cold water and bottom feeding
fish that interact with the sediment - Cod and Mackerel
- Intake from air, soil, and water is usually much
smaller
9Effects on the Human Body
Skin Cancer
Cancer of the Nasal Passages
Lung Cancer
Kidney Cancer
Liver Cancer
Prostate Cancer
Bladder Cancer
Skin Lesions
Diabetes
Death
10Bangladesh
- One of the biggest problems in Bangladesh is
arsenic contamination, which has forced
authorities to seal thousands of wells across the
country. - Health officials say one-third of the country now
has arsenic contaminated wells - Estimated that out of the total population of 125
million, 35 - 77 million are at risk of drinking
contaminated water.
Mohammad Ismail shows his palms after doctors
removed his two fingers due to arsenic
contamination
11USGS 2001 Arsenic Contamination
- Arsenic levels as high as 92 ppb have been
detected in U.S drinking water. - Around 3 million people are at risk.
- As of 2006 EPA standards changed from 50 ppb to
10 ppb.
12Ecosystem Exposure
- Ecosystem exposure primarily occurs through
surface runoff and atmospheric dry fall. - Arsenic levels are higher in biota collected near
anthropogenic sources or in areas with geothermal
activity. - Terrestrial plants may accumulate arsenic by root
uptake from the soil or by adsorption of airborne
arsenic deposited on the leaves.
13Effects on biota
Reproductive Failure
Growth Inhibition
Decrease Species Diversity
Behavioral Effects
Lethality
Decreased Photosynthetic Rates of Primary
Producers
- Arsenic contaminated environments are
characterized by limited species abundance and
diversity
14Arsenic Removal
- Only two known treatment options for arsenic
contaminated waters - Expensive Chemical Treatments
- Tertiary water treatments like chemical
precipitation, ion exchange, membrane filtration,
etc.. - OR
- Inexpensive Environmental Treatments
- Phytoremediation!
15Definitions
- Phytoremediation- an emerging technology that
uses various plants to degrade, extract, contain,
or immobilize contaminants from soil and water. - Hyperaccumulators- plants that accumulate high
amounts of a toxic substance, usually a metal or
metalloid, in their shoots during normal growth
and reproduction.
16Arsenic Phytoremediation
- Potential for phytoremediation of sites
contaminated with arsenic has been of great
interest since the 2001 discovery of the Chinese
brake fern (Pteris vittata) as an arsenic
hyperaccumulating plant species.
Dr. Lena Ma
17Ma et al. 2001 Results
- First column shows initial arsenic concentration
at various levels in the soil. - The next two columns show arsenic uptake (amount
transferred into plant biomass) after 2 and 6
weeks of exposure - Brake fern was shown to quickly accumulate
arsenic into its biomass.
18Ma et al. 2001 Results
- Figure B shows arsenic accumulation over time
- Figure C shows arsenic accumulation with various
species of arsenic at 50 ppm grown for 18 weeks. - Brake fern was shown to hyperaccumulate several
arsenic species at varying concentration levels.
19Gaps in the Research
- Problems with brake fern
- Invasive species
- Pest problem in Florida and other southern states
- Rooted species
- Difficult to harvest and use for cleaning aquatic
systems - Solution Discover a plant that is easily
harvested, has a native range encompassing Ohio,
and hyperaccumulates arsenic.
20Azolla caroliniana
- Floating aquatic macrophyte
- Native to U.S
- Research has shown Azollas hyperaccumulating
characteristics
21(No Transcript)
22Azolla Caroliniana Research
- Recent research shows that Azolla caroliniana can
accumulate large quantities of - Mercury
- Chromium
- Lead
- Cadmium
- Bennicelli et al. (2004) and Stêpniewska et al.
(2005)
23Results from Bennicelli et al. 2004
- Figures A-C show the arsenic levels in a
hydroponic system V.S time - Azolla is accumulating (taking these metals out
of solution) rather quickly.
24Results from Bennicelli et al. 2004
- The bar graph shows the growth of azolla at
various treatments compared to the control - Azollas growth was minimally inhibited
- About all the treatments more than doubled their
growth within 12 days
25Summing Up
- Arsenic hyperaccumulators have been identified
- Brake fern, moonlight fern, silver fern
- Currently, no arsenic hyperaccumulating plant
species native to Ohio have been identified. - No potential application
- Azolla caroliniana has potential to fill research
gaps - Fast growing
- Native to eastern half of U.S
- Can potentially hyperaccumulate arsenic
26Rational
- Ferns affinity for moist habitat
- Evolved in anoxic, potentially toxic habitats
- Reduced conditions cause the release of heavy
metals into solution. - Arsenic solubility maximum under reduced
conditions. - Growth is minimally inhibited by arsenic
- Arsenic competes with phosphorous for plant
uptake - Actually stimulate growth in initial stages.
27Objectives
- Quantify the phytofiltration capacity of A.
caroliniana - Compare uptake efficiency of A. caroliniana
between the various species of arsenic and
concentrations used. - Compare effects on growth of A. caroliniana by
the various species of arsenic.
28Future of Phytoremediation
- Constructed wetland systems that are
- Inexpensive
- Efficient
- Environmentally friendly
- My Research Project!
29Questions ?