Bio Remediation of Lead

8/3/2019 Bio Remediation of Lead

1/16

Daniel Henderson, Sean Nugent

Mentor:

Dr. F. Ryvkin

Chemistry Department, Emmanuel College, Boston MA


2/16

The use of plants for cleaning up contamination of soil,groundwater, surface water and air.

Proven to be a successful way to decrease the concentration ofsome common pollutants in these sites

Many laboratory and field tests have demonstrated that plantsand other vegetation can absorb, transform, or contain a variety

of contaminants, including soft and heavy metals and volatileorganics through absorption and other activity in the root zone.

Major barrier to the implementation of bioremediation is that it is

new and not fully developed and there is little regulatoryexperience with it.

~

BACKGROUND


3/16

Lead is a highly toxic metal,dangerous to children at levelsgreater than 25 g/dL

Causes behavioral problems,learning disabilities, seizures, slowgrowth, hearing problems, anddeath.

Lead has a cumulative effect onchildren who are at higher risk forexposure and absorption than adults

US Standards for leadconcentration:

-In Soil: 400 ppm-In Paint: 5,000 ppm

LEAD:

behavioral problemslearning disabilitiesseizuresreproductive problems (in both men andwomen)

High blood pressureDigestive problemsNerve disordersMemory problemsMuscle and joint pain

and even death.Lead is most dangerous concerning thehealth of a child. It can slow growth andcause hearing problems and headachesas well as the same symptoms adults

suffer from.


4/16

Arsenic: Disrupts the digestive system

Liver and kidney damage.

Can also lead to central and peripheral nervous system disorders.

Mercury (primarily from methylmercury):Impairs the development of the fetus causing impacts on:

Cognitive thinkingMemoryAttention

LanguageFine motor visual and spatial skillsCadmium:

diarrhea

muscle crampssalivationsensory disturbancesliver injuryconvulsionsshock and renal failureNauseaVomiting


5/16

Aquatic organisms may be adversely affected by heavy metals inthe environment.

The toxicity is largely a function of the water chemistry and sedimentcomposition in the surface water system

Slightly elevated metal levels in natural waters may cause thefollowing effects in aquatic organisms:

histological or morphological change in tissues changes in physiology, such as suppression of growth and

development

change in biochemistry, such as enzyme activity and blood

chemistry change in behavior and changes in reproduction

Research has shown that aquatic plants are not able to successfullyregulate metal uptake, and so the water resource should be managed

for the protection of fish and invertebrates, in order to ensure aquaticplant survivability.


6/16


7/16

Perennial fresh water flowering plant Widely distributed in tropical and sub-tropical

regions

Leaves possess swollen portions that act as floats Extensive root system projects beneath water

surface

Under ideal growing conditions the plants form afloating mat that can double in size in two weeks

Water hyacinth plants have been shown to absorb

remarkable amounts of pollutants such as cadmium,zinc and arsenic


8/16

Plants used to decontaminate soilsthrough the process of

bioremediation must do one ormore of the following :

take up contaminants from soil

particles and/or soil liquid into theirroots

bind the contaminant into their root

tissue, physically and/or chemically

transport the contaminant fromtheir roots into growing shoots

prevent or inhibit the contaminantfrom leaching out of the soil


9/16

Negative effects of Nutrient Enriched

Environments on Bioremediation:Bioavailable fraction of metals reduces as a

result of binding to nutrient anions.

Competition between metals and nutrientcations for uptake sites results in decreased

absorption.


10/16

Positive effects of Nutrient Enriched

Environments on Bioremediation:Increased nutrients promotes plant growth.

Plant growth in turn creates an increasing

number of uptake sites for metals.

Increased uptake sites for metals increases

the uptake and concentrations of metals in theplants.

continued


11/16

All plants were cultivated in plastic tubs containing artificialpond water

Lead nitrate was added to the container with the experimentalplants Control plants were not exposed to lead solution At predetermined intervals samples of water and plants were

removed for analysis Water samples were analyzed for the presence of lead using

flame atomic absorption (210VG Buck Scientific Model) Plants were divided into separate root and leaf samples Root and leaf samples were oven dried, weighed and extracted

by boiling in a cocktail of nitric and hydrochloric acid After filtration, the extracts were analyzed in the same fashion


12/16

Lead Stems vs. Lead Control

0

0.5

1

1.5

2

2.5

3

Day 0 Day 2 Day 5

ppm Lead Stems

Control Stems


13/16

0

2

4

6

8

10

12

[Pb](ppm

)

Day 1 Day 2

Plant with Lead vs. Control

Control Plant roots w ith Lead


14/16

Data shows that water hyacinth plants effectively remove lead fromsolution. The water hyacinth plant works as a bioaccumulator,drawing heavy metal ions in solution into the roots and up through

the stem and stolons, leaves, etc. Within five days there was overfour times less lead in the water than there was in the plant roots,and the data from Day 5 samples (both roots and stems exposed to2ppm Lead) suggest the mechanics of lead uptake. The lead ions

are drawn up via diffusion into the plant roots and up the stem andleaf systems.


15/16

Determine how the nutrient levels effect the

absorption levels of the water hyacinth, andinvestigate the ion selectivity of the waterhyacinth in the uptake of heavy metals

Investigate nutrients such as potassium, nitrates,and phosphates for their individual effect on thewater hyacinths uptake of heavy metals such as

lead and cadmium.


16/16

We would like to express our deepest gratitude to ourfaculty mentors for encouragement, patience, andconstant support of this research project.

We are also grateful to Sharon Patris for initiating theproject, and to Eric Camire and Laura Graziano forassisting.

Documents

Bio Remediation of Lead