The Potential of Azolla caroliniana to Remove Arsenic From Contaminated Wastewater - PowerPoint PPT Presentation

1 / 29
About This Presentation
Title:

The Potential of Azolla caroliniana to Remove Arsenic From Contaminated Wastewater

Description:

Beautiful, but Deadly. Historical Uses. Poison of Kings and the King of Poisons. ... Mohammad Ismail shows his palms after doctors removed his two fingers due to ... – PowerPoint PPT presentation

Number of Views:722
Avg rating:5.0/5.0
Slides: 30
Provided by: alexmart
Category:

less

Transcript and Presenter's Notes

Title: The Potential of Azolla caroliniana to Remove Arsenic From Contaminated Wastewater


1
The Potential of Azolla caroliniana to Remove
Arsenic From Contaminated Wastewater
  • Prepared by
  • Alex Duncan
  • MS Student
  • Dept. Environmental Science

2
Agenda
  • 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

3
What 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

4
Where Does It Come From ?
  • Natural Sources
  • Weathering of Bedrock
  • the most common of which is arsenopyrite.
  • Anthropogenic Byproducts
  • Industry and Agriculture

5
Beautiful, but Deadly
6
Historical 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.

7
Anthropogenic Sources
Burning Fossil Fuels
Wood Preservatives
Leaded gasoline
Fungicides
Electronics Manufacturing
Herbicides
Clarifying Glass
Insecticides
Many More
8
Human 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

9
Effects 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
10
Bangladesh
  • 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
11
USGS 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.

12
Ecosystem 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.

13
Effects 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

14
Arsenic 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!

15
Definitions
  • 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.

16
Arsenic 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
17
Ma 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.

18
Ma 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.

19
Gaps 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.

20
Azolla caroliniana
  • Floating aquatic macrophyte
  • Native to U.S
  • Research has shown Azollas hyperaccumulating
    characteristics

21
(No Transcript)
22
Azolla 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)

23
Results 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.

24
Results 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

25
Summing 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

26
Rational
  • 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.

27
Objectives
  • 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.

28
Future of Phytoremediation
  • Constructed wetland systems that are
  • Inexpensive
  • Efficient
  • Environmentally friendly
  • My Research Project!

29
Questions ?
Write a Comment
User Comments (0)
About PowerShow.com